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Sample records for air stream prior

  1. Evaluation of an adsorption system to concentrate VOC in air streams prior to catalytic incineration.

    PubMed

    Campesi, María A; Luzi, Carlos D; Barreto, Guillermo F; Martínez, Osvaldo M

    2015-05-01

    Catalytic combustion is a well-developed process for the removal of volatile organic compounds (VOCs). In order to reduce both the amount of catalyst needed for incineration and the surface area of recuperative heat exchangers, an evaluation of the use of thermal swing adsorption as a previous step for VOC concentration is made. An air stream containing ethyl acetate and ethanol (employed as solvents in printing processes) has been taken as a case study. Based on the characteristics of the adsorption/desorption system and the properties of the stream to be treated, a monolithic rotor concentrator with activated carbon as adsorbent material is adopted. Once the temperature of the inlet desorption stream TD is chosen, the minimum possible desorption flow rate, WD,min, and the amount of adsorbent material can be properly defined according to the extent of the Mass Transfer Zone (MTZ) at the end of the adsorption stage. An approximate procedure to speed up the calculations needed for sizing the bed and predicting the operating variables is also presented. In the case studied here, the concentration of the VOC stream can reach 6 times that of the primary effluent when TD = 200 °C is chosen.

  2. Evaluation of an adsorption system to concentrate VOC in air streams prior to catalytic incineration.

    PubMed

    Campesi, María A; Luzi, Carlos D; Barreto, Guillermo F; Martínez, Osvaldo M

    2015-05-01

    Catalytic combustion is a well-developed process for the removal of volatile organic compounds (VOCs). In order to reduce both the amount of catalyst needed for incineration and the surface area of recuperative heat exchangers, an evaluation of the use of thermal swing adsorption as a previous step for VOC concentration is made. An air stream containing ethyl acetate and ethanol (employed as solvents in printing processes) has been taken as a case study. Based on the characteristics of the adsorption/desorption system and the properties of the stream to be treated, a monolithic rotor concentrator with activated carbon as adsorbent material is adopted. Once the temperature of the inlet desorption stream TD is chosen, the minimum possible desorption flow rate, WD,min, and the amount of adsorbent material can be properly defined according to the extent of the Mass Transfer Zone (MTZ) at the end of the adsorption stage. An approximate procedure to speed up the calculations needed for sizing the bed and predicting the operating variables is also presented. In the case studied here, the concentration of the VOC stream can reach 6 times that of the primary effluent when TD = 200 °C is chosen. PMID:25734958

  3. Pattern Specificity in the Effect of Prior [delta]f on Auditory Stream Segregation

    ERIC Educational Resources Information Center

    Snyder, Joel S.; Weintraub, David M.

    2011-01-01

    During repeating sequences of low (A) and high (B) tones, perception of two separate streams ("streaming") increases with greater frequency separation ([delta]f) between the A and B tones; in contrast, a prior context with large [delta]f results in less streaming during a subsequent test pattern. The purpose of the present study was to investigate…

  4. A Delicate Balance: Hovering Balloons in an Air Stream

    ERIC Educational Resources Information Center

    Gluck, Paul

    2006-01-01

    Science museums and popular physics shows often exhibit a blower in whose air stream a ball is held hovering in equilibrium some distance above the jet's orifice. The weight of the ball, "mg," is balanced by the drag force of the turbulent air stream, often written as ?Cv[superscript 2]A, where "?" and "v" are the…

  5. Evolution of injected air stream in granular bed

    NASA Astrophysics Data System (ADS)

    Maiti, Ritwik; Das, Gargi; Das, Prasanta

    2015-11-01

    An air stream injected through an orifice into a granular bed creates intriguing but aesthetically exotic patterns. The interaction of air with an aggregate of cohesionless granules presents evolution of patterns from stationary bubble to meandering filament and finally to a floating canopy with the increase of air velocity.

  6. Attaining a steady air stream in wind tunnels

    NASA Technical Reports Server (NTRS)

    Prandtl, L

    1933-01-01

    Many experimental arrangements of varying kind involve the problems of assuring a large, steady air stream both as to volume and to time. For this reason a separate discussion of the methods by which this is achieved should prove of particular interest. Motors and blades receive special attention and a review of existent wind tunnels is also provided.

  7. Multiple-orifice liquid injection into hypersonic air streams.

    NASA Technical Reports Server (NTRS)

    Weaver, W. L.

    1972-01-01

    Review of oblique water and fluorocarbon injection test results obtained in experimental studies of the effects of multiple-orifice liquid injection into hypersonic air streams. The results include the finding that maximum lateral penetration from such injections increases linearly with the square root of the jet-to-freestream dynamic-pressure ratio and is proportional to an equivalent orifice diameter.

  8. Control of gas contaminants in air streams through biofiltration

    SciTech Connect

    Holt, T.; Lackey, L.

    1996-11-01

    According to the National Institute for Occupational Safety and Health (NIOSH), the maximum styrene concentration allowed in the work place is 50 ppm for up to a 10-hour work day during a 40-hour work week. The US EPA has classified styrene as one of the 189 hazardous air pollutants listed under Title 3 of the Clean Air Act Amendments to be reduced by a factor of 90% by the year 2000. Significant quantities of styrene are emitted to the atmosphere each year by boat manufacturers. A typical fiberglass boat manufacturing facility can emit over 273 metric tons/year of styrene. The concentration of styrene in the industrial exhaust gas ranges from 20 to 100 ppmv. Such dilute, high volume organically tainted air streams can make conventional abatement technologies such as thermal incineration, adsorption, or absorption technically incompetent or prohibitively expensive. An efficient, innovative, and economical means of remediating styrene vapors would be of value to industries and to the environment. Biofilter technology depends on microorganisms that are immobilized on the packing material in a solid phase reactor to remove or degrade environmentally undesirable compounds contaminating gas streams. The technology is especially successful for treating large volumes of air containing low concentrations of contaminants. The objective of this study was to investigate the feasibility of using biofiltration to treat waste gas streams containing styrene and to determine the critical design and operating parameters for such a system.

  9. Vinyl chloride removal from an air stream by biotrickling filter.

    PubMed

    Faraj, S H Esmaeili; Esfahany, M Nasr; Kadivar, M; Zilouei, H

    2012-01-01

    A biofiltration process was used for degradation of vinyl chloride as a hazardous material in the air stream. Three biotrickling filters in series-parallel allowing uniform feed and moisture distribution all over the bed were used. Granular activated carbon mixed with compost was employed as carrier bed. The biological culture consisted of mixture of activated sludge from PVC wastewater treatment plant. Concurrent flow of gas and liquid was used in the bed. Results indicated that during the operation period of 110 days, the biotrickling bed was able to remove over 35% of inlet vinyl chloride. Maximum elimination capacity was calculated to be 0.56 g.m(-3).hr(-1). The amount of chlorine accumulated in the circulating liquid due to the degradation of vinyl chloride was measured to be equal to the vinyl chloride removed from the air stream.

  10. Stream air temperature relations to classify stream ground water interactions in a karst setting, central Pennsylvania, USA

    NASA Astrophysics Data System (ADS)

    O'Driscoll, Michael A.; DeWalle, David R.

    2006-09-01

    SummaryStream-ground water interactions in karst vary from complete losses through swallow holes, to reemergences from springs. Our study objective was to compare stream-air temperature and energy exchange relationships across various stream-ground water relationships in a carbonate watershed. It was hypothesized that ground water-fed stream segments could be distinguished from perched/losing segments using stream-air temperature relationships. Two types of computations were conducted: (1) comparisons of stream-air temperature relationships for the period of October 1999-September 2002 at 12 sites in the Spring Creek drainage and (2) detailed energy budget computations for the same period for ground water-dominated Thompson Run and Lower Buffalo Run, a stream with negligible ground water inputs. Weekly average air temperatures and stream temperatures were highly correlated, but slopes and intercepts of the relationship varied for the 12 sites. Slopes ranged from 0.19 to 0.67 and intercepts ranged from 3.23 to 9.07 °C. A two-component mixing model with end members of ground water and actual stream temperatures indicated that the slope and intercept of the stream-air temperature relationship was controlled by ground water inputs. Streams with large ground water inputs had greater intercepts and lesser slopes than streams that were seasonally losing, perched, and/or distant from ground water inputs. Energy fluxes across the air-water interface were greatest for the ground water-fed stream due to increased longwave, latent, and sensible heat losses from the stream in winter when large temperature and vapor pressure differences existed between the stream and air. Advection of ground water was an important source and sink for heat in the ground water-fed stream, depending on season. In contrast, along the seasonally losing stream reach, advection was of minimal importance and stream temperatures were dominated by energy exchange across the air- water interface. Overall

  11. Control of aromatic-waste air streams by soil bioreactors

    SciTech Connect

    Miller, D.E.; Canter, L.W.

    1991-01-01

    Contamination of groundwater resources is a serious environmental problem which is continuing to increase in occurrence in the United States. It has been reported that leaking underground gasoline storage tanks may pose the most serious threat of all sources of groundwater contamination. Gasolines are comprised of a variety of aliphatic and aromatic hydrocarbons. The aromatic portion consists primarily of benzene, toluene, ethylbenzene, and xylenes (BTEX compounds). BTEX compounds are also among the most frequency identified substances at Superfund sites. Pump and treat well systems are the most common and frequently used technique for aquifer restoration. Treatment is often in the form of air stripping to remove the volatile components from the contaminated water. Additionally, soil ventilation processes have been used to remove volatile components from the vadose zone. Both air stripping and soil ventilation produce a waste gas stream containing volatile compounds which is normally treated by carbon adsorption or incineration. Both treatment processes require a substantial capital investment and continual operation and maintenance expenditures. The objective of the study was to examine the potential of using soil bioreactors to treat a waste gas stream produced by air stripping or soil ventilation process. Previous studies have shown that various hydrocarbons can be successfully treated with soils. The study examined the removal of BTEX compounds within soil columns and the influence of soil type, inlet concentration, and inlet flow rate on the removal efficiency.

  12. Investigation of air stream from combustor-liner air entry holes, 3

    NASA Technical Reports Server (NTRS)

    Aiba, T.; Nakano, T.

    1979-01-01

    Jets flowing from air entry holes of the combustor liner of a gas turbine were investigated. Cold air was supplied through the air entry holes into the primary hot gas flows. The mass flow of the primary hot gas and issuing jets was measured, and the behavior of the air jets was studied by the measurement of the temperature distribution of the gas mixture. The air jets flowing from three circular air entry holes, single streamwise long holes, and two opposing circular holes, parallel to the primary flow were studied along with the effects of jet and gas stream velocities, and of gas temperature. The discharge coefficient, the maximum penetration of the jets, the jet flow path, the mixing of the jets, and temperature distribution across the jets were investigated. Empirical expressions which describe the characteristics of the jets under the conditions of the experiments were formulated.

  13. Biological removal of carbon disulfide from waste air streams

    SciTech Connect

    Hugler, W.; Acosta, C.; Revah, S.

    1999-09-30

    A pilot-scale biological control system for the treatment of 3,400 m{sup 3} h{sup {minus}1} of a gaseous stream containing up to 7.8 g CS{sub 2} m{sup {minus}3} and trace amounts of hydrogen sulfide (H{sub 2}S) was installed in a cellulose sponge manufacturing facility. The objective was to demonstrate the capability of the process to attain sustained removal efficiencies of 90% for CS{sub 2} and 99% for H{sub 2}S. The system consisted of two sequential biotrickling reactors, which had been previously inoculated with an adapted microbial consortium. During the pilot test, stable removal efficiency and elimination capacity of +90% and 220g CS{sub 2} m{sup {minus}3} h{sup {minus}1}, respectively, were attained with an empty bed residence time (EBTR) of 33 seconds for a period of several weeks. Efficiencies greater than 99% were always obtained for H{sub 2}S. Based on the results, the system was determined to be an effective process to remediate waste air streams containing reduced sulfur compounds generated at cellulose sponge facilities.

  14. Can air temperature be used to project influences of climate change on stream temperature?

    USGS Publications Warehouse

    Arismendi, Ivan; Safeeq, Mohammad; Dunham, Jason B.; Johnson, Sherri L.

    2014-01-01

    Worldwide, lack of data on stream temperature has motivated the use of regression-based statistical models to predict stream temperatures based on more widely available data on air temperatures. Such models have been widely applied to project responses of stream temperatures under climate change, but the performance of these models has not been fully evaluated. To address this knowledge gap, we examined the performance of two widely used linear and nonlinear regression models that predict stream temperatures based on air temperatures. We evaluated model performance and temporal stability of model parameters in a suite of regulated and unregulated streams with 11–44 years of stream temperature data. Although such models may have validity when predicting stream temperatures within the span of time that corresponds to the data used to develop them, model predictions did not transfer well to other time periods. Validation of model predictions of most recent stream temperatures, based on air temperature–stream temperature relationships from previous time periods often showed poor performance when compared with observed stream temperatures. Overall, model predictions were less robust in regulated streams and they frequently failed in detecting the coldest and warmest temperatures within all sites. In many cases, the magnitude of errors in these predictions falls within a range that equals or exceeds the magnitude of future projections of climate-related changes in stream temperatures reported for the region we studied (between 0.5 and 3.0 °C by 2080). The limited ability of regression-based statistical models to accurately project stream temperatures over time likely stems from the fact that underlying processes at play, namely the heat budgets of air and water, are distinctive in each medium and vary among localities and through time.

  15. Scrubbing of contaminants from contaminated air streams with aerogel materials with optional photocatalytic destruction

    DOEpatents

    Attia, Yosry A.

    2000-01-01

    Disclosed is a method for separating a vaporous or gaseous contaminant from an air stream contaminated therewith. This method includes the steps of: (a) passing said contaminated air into a contact zone in which is disposed an aerogel material capable of selecting adsorbing said contaminant from air and therein contacting said contaminated air with an aerogel material; and (b) withdrawing from said zone, air depleted of said contaminant. For present purposes, "contaminant" means a material not naturally occurring in ambient air and/or a material naturally occurring in air but present at a concentration above that found in ambient air. Thus, the present invention scrubs (or treats) air for the purpose of returning it to its ambient composition. Also disclosed herein is a process for the photocatalytic destruction of contaminants from an air stream wherein the contaminated air stream is passed into a control cell or contact zone in which is disposed a photocatalytic aerogel and exposing said aerogel to ultraviolet (UV) radiation for photocatalytically destroying the adsorbed contaminant, and withdrawing from said cell an exhaust air stream depleted in said contaminant.

  16. Penetration of Air Jets Issuing from Circular, Square, and Elliptical Orifices Directed Perpendicularly to an Air Stream

    NASA Technical Reports Server (NTRS)

    Ruggeri, Robert S.; Callaghan, Edmund E.; Bowden, Dean T.

    1950-01-01

    An experimental investigation was conducted to determine the penetration of air jets d.irected perpendicularlY to an air stream. Jets Issuing from circular, square, and. elliptical orifices were investigated. and. the jet penetration at a position downstream of the orifice was determined- as a function of jet density, jet velocity, air-stream d.enaity, air-stream velocity, effective jet diameter, and. orifice flow coeffIcient. The jet penetrations were determined for nearly constant values of air-stream density at three tunnel-air velocities arid for a large range of Jet velocities and. densities. The results were correlated in terms of dimensionless parameters and the penetrations of the various shapes were compared. Greater penetration was obtained. with the square orifices and the elliptical orifices having an axis ratio of 4:1 at low tunnel-air velocities and low jet pressures than for the other orifices investigated. The square orifices gave the best penetrations at the higher values of tunnel-air velocity and jet total pressure.

  17. The design of an air filtration system to clean high temperature/high humidity radioactive air streams

    SciTech Connect

    Proffitt, T.H.; Burket, J.P.

    1994-12-31

    During normal operating processes or waste remediation efforts high efficiency (HEPA) filtration systems are used to remove particulate contamination from air streams. These HEPA filtration systems can accommodate a range of air humidities and temperatures and still retain their effectiveness. However, when the combination of high humidity and high temperature are present the effect of these highly saturated air streams can be detrimental to a HEPA filtration system. Couple this highly saturated air stream with the effect of radioactivity and a case for a {open_quotes}specialized{close_quotes} HEPA filter system can be made. However, using fundamental laws of heat transfer it is possible to design a a HEPA a filter system that can operate in a high temperature/high humidity radioactive environment.

  18. How an Air Stream Can Support a Cupcake

    NASA Astrophysics Data System (ADS)

    Jones, Evan

    2015-05-01

    Variations of a demonstration in which a sheet of paper or a bead is levitated in a grazing stream as from one's breath have been published in several sources.1-4 Even a massive ball can be deflected into the robust flow from a leaf blower.5 The attraction is surprising because it is often quite stable and seems to conflict with the familiar transient repulsion felt from a stream's impact.

  19. Air - water temperature relationships in the trout streams of southeastern Minnesota’s carbonate - sandstone landscape

    USGS Publications Warehouse

    Krider, Lori A.; Magner, Joseph A.; Perry, Jim; Vondracek, Bruce C.; Ferrington, Leonard C.

    2013-01-01

    Carbonate-sandstone geology in southeastern Minnesota creates a heterogeneous landscape of springs, seeps, and sinkholes that supply groundwater into streams. Air temperatures are effective predictors of water temperature in surface-water dominated streams. However, no published work investigates the relationship between air and water temperatures in groundwater-fed streams (GWFS) across watersheds. We used simple linear regressions to examine weekly air-water temperature relationships for 40 GWFS in southeastern Minnesota. A 40-stream, composite linear regression model has a slope of 0.38, an intercept of 6.63, and R2 of 0.83. The regression models for GWFS have lower slopes and higher intercepts in comparison to surface-water dominated streams. Regression models for streams with high R2 values offer promise for use as predictive tools for future climate conditions. Climate change is expected to alter the thermal regime of groundwater-fed systems, but will do so at a slower rate than surface-water dominated systems. A regression model of intercept vs. slope can be used to identify streams for which water temperatures are more meteorologically than groundwater controlled, and thus more vulnerable to climate change. Such relationships can be used to guide restoration vs. management strategies to protect trout streams.

  20. Watershed geomorphology and snowmelt control stream thermal sensitivity to air temperature

    NASA Astrophysics Data System (ADS)

    Lisi, Peter J.; Schindler, Daniel E.; Cline, Timothy J.; Scheuerell, Mark D.; Walsh, Patrick B.

    2015-05-01

    How local geomorphic and hydrologic features mediate the sensitivity of stream thermal regimes to variation in climatic conditions remains a critical uncertainty in understanding aquatic ecosystem responses to climate change. We used stable isotopes of hydrogen and oxygen to estimate contributions of snow and rainfall to 80 boreal streams and show that differences in snow contribution are controlled by watershed topography. Time series analysis of stream thermal regimes revealed that streams in rain-dominated, low-elevation watersheds were 5-8 times more sensitive to variation in summer air temperature compared to streams draining steeper topography whose flows were dominated by snowmelt. This effect was more pronounced across the landscape in early summer and less distinct in late summer. Thus, the impact of climate warming on freshwater thermal regimes will be spatially heterogeneous across river basins as controlled by geomorphic features. However, thermal heterogeneity may be lost with reduced snowpack and increased ratios of rain to snow in stream discharge.

  1. How an Air Stream Can Support a Cupcake

    ERIC Educational Resources Information Center

    Jones, Evan

    2015-01-01

    Variations of a demonstration in which a sheet of paper or a bead is levitated in a grazing stream as from one's breath have been published in several sources. Even a massive ball can be deflected into the robust flow from a leaf blower. The attraction is surprising because it is often quite stable and seems to conflict with the familiar transient…

  2. Assessment of endocrine-disrupting chemicals attenuation in a coastal plain stream prior to wastewater treatment plant closure

    USGS Publications Warehouse

    Bradley, Paul M.; Journey, Celeste A.

    2014-01-01

    The U.S. Geological Survey is conducting a combined pre/post-closure assessment at a long-term wastewater treatment plant (WWTP) site at Fort Gordon near Augusta, Georgia. Here, we assess select endocrine-active chemicals and benthic macroinvertebrate community structure prior to closure of the WWTP. Substantial downstream transport and limited instream attenuation of endocrine-disrupting chemicals (EDCs) was observed in Spirit Creek over a 2.2-km stream segment downstream of the WWTP outfall. A modest decline (less than 20% in all cases) in surface water detections was observed with increasing distance downstream of the WWTP and attributed to partitioning to the sediment. Estrogens detected in surface water in this study included estrone (E1), 17β-estradiol (E2), and estriol (E3). The 5 ng/l and higher mean estrogen concentrations observed in downstream locations indicated that the potential for endocrine disruption was substantial. Concentrations of alkylphenol ethoxylate (APE) metabolite EDCs also remained statistically elevated above levels observed at the upstream control site. Wastewater-derived pharmaceutical and APE metabolites were detected in the outflow of Spirit Lake, indicating the potential for EDC transport to aquatic ecosystems downstream of Fort Gordon. The results indicate substantial EDC occurrence, downstream transport, and persistence under continuous supply conditions and provide a baseline for a rare evaluation of ecosystem response to WWTP closure.

  3. Air Pollution and Acid Rain, Report 5. The effects of air pollution and acid rain on fish, wildlife, and their habitats: rivers and streams

    SciTech Connect

    Potter, W.; Chang, B.K.Y.

    1982-06-01

    This report on rivers and streams is part of a series synthesizing the results of scientific research related to the effects of air pollution and acid deposition on fish and wildlife resources. The effects of photochemical oxidants, particulates, and acidifying air pollutants on water quality and river and stream biota are summarized. The characteristics that reflect river and stream sensitivity to air pollutants, in particular acidifying pollutants, are presented. Socioeconomic aspects of air pollution impacts on river and stream ecosystems are discussed. 71 references, 2 figures, 5 tables.

  4. Penetration of Liquid Jets into a High-velocity Air Stream

    NASA Technical Reports Server (NTRS)

    Chelko, Louis J

    1950-01-01

    Data are presented showing the penetration characteristics of liquid jets directed approximately perpendicular to a high-velocity air stream for jet-nozzle-throat diameters from 0.0135 to 0.0625 inch, air stream densities from 0.0805 to 0.1365 pound per cubic foot, liquid jet velocities from 168.1 to 229.0 feet per second and a liquid jet density of approximately 62 pounds per cubic foot. The data were analyzed and a correlation was developed that permitted the determination of the penetration length of the liquid jet for any operation condition within the range of variables investigated.

  5. Apparatus for mixing char-ash into coal stream

    DOEpatents

    Blaskowski, Henry J.

    1982-03-16

    Apparatus for obtaining complete mixing of char with coal prior to the introduction of the mixture into the combustor (30) of a coal gasifier (10). The coal is carried in one air stream (22), and the char in another air stream (54), to a riffle plate arrangement (26), where the streams of solid are intimately mixed or blended.

  6. On the behaviour of a stressed cotton canopy in a direct air stream

    NASA Technical Reports Server (NTRS)

    Schutt, J. B.; Newcomb, W. W.

    1986-01-01

    Reflectance variations of a stressed cotton canopy were conducted in the presence of a fan-generated air stream to investigate the effects of air movement and the resulting temperature changes on remotely-sensed data. The initial drop in reflectance after application of the air stream was found to be greatest in the morning because leaf turgor was at a maximum, enabling leaves on the windward side of the canopy to assume surprisingly stable vertical positions. By afternoon, a reduction in leaf turgor was responsible for less stem displacement and consequently a reduction in light-trapping capability. However, reflectance oscillations were greater because the leaves had become sufficiently limp to flutter at the edges and about the petioles exposing both adaxial and abaxial surfaces to the incident light.

  7. The transference of heat from a hot plate to an air stream

    NASA Technical Reports Server (NTRS)

    Elias, Franz

    1931-01-01

    The object of the present study was to define experimentally the field of temperature and velocity in a heated flat plate when exposed to an air stream whose direction is parallel to it, then calculate therefrom the heat transference and the friction past the flat plate, and lastly, compare the test data with the mathematical theory. To ensure comparable results, we were to actually obtain or else approximate: a) two-dimensional flow; b) constant plate temperature in the direction of the stream. To approximate the flow in two dimensions, we chose a relatively wide plate and measured the velocity and temperature in the median plane.

  8. Alcohol issues prior to training in the United States Air Force.

    PubMed

    Derefinko, Karen J; Klesges, Robert C; Bursac, Zoran; Little, Melissa A; Hryshko-Mullen, Ann; Talcott, Gerald W

    2016-07-01

    The negative impact of alcohol is a significant concern to the US military given the costs associated with alcohol-related offenses. Despite considerable research in active duty personnel, relatively little is known about the current extent of alcohol use among incoming recruits. We examined the history of alcohol use and harmful patterns of alcohol consumption among recruits entering the United States Air Force (USAF; N=50,549) over the span of 4 years (2010-2014). Across all years, drinking rates reflected national average trends for those aged 18-24 (NIDA, 2014). However, when abstainers were excluded, those under 21 (n=10,568) reported an average of 18.4 drinks per week, whereas those age 21 and over (n=14,188) reported an average of 14.1 drinks per week, suggesting that for those who drink, those under 21 are exhibiting more risky drinking rates. Alcohol Use Disorders Identification Task (AUDIT) scores for drinkers reflected these same trends. For those under 21, 58% scored in risk categories of 2 or higher (risky drinking warranting attention), compared with 40% for those age 21 and over. These scores indicate that for recruits in the USAF, approximately half report alcohol use immediately prior to basic training, resulting in the inheritance of these potential alcohol related issues for those conducting training of these recruits. Based upon these numbers, brief alcohol interventions could have a potential positive impact on individuals in their initial training stages of the USAF to prevent these baseline issues from resulting in problems later in their military careers. PMID:26945450

  9. Electro-aerodynamic instability of a thin dielectric liquid sheet sprayed with an air stream.

    PubMed

    El-Sayed, M F

    1999-12-01

    The instability of a thin sheet of dielectric liquid moving in the same direction as an air stream in the presence of a uniform horizontal electric field is studied theoretically. It is found that aerodynamic-enhanced instability occurs if the Weber number is much less than a critical value related to the ratio of the air and liquid stream velocities, the electric field, and the dielectric constant values. The electric field is found to have a stabilizing effect, and there exists a critical Weber number above which instability is suppressed by the surface tension effect. The condition for disintegrating the sheet is obtained in terms of the electric field values, and some limiting cases are recovered.

  10. Sensitivity of New England Stream Temperatures to Air Temperature and Precipitation Under Projected Climate

    NASA Astrophysics Data System (ADS)

    Huang, T.; Samal, N. R.; Wollheim, W. M.; Stewart, R. J.; Zuidema, S.; Prousevitch, A.; Glidden, S.

    2015-12-01

    The thermal response of streams and rivers to changing climate will influence aquatic habitat. This study examines the impact that changing climate has on stream temperatures in the Merrimack River, NH/MA USA using the Framework for Aquatic Modeling in the Earth System (FrAMES), a spatially distributed river network model driven by air temperature, air humidity, wind speed, precipitation, and solar radiation. Streamflow and water temperatures are simulated at a 45-second (latitude x longitude) river grid resolution for 135 years under historical and projected climate variability. Contemporary streamflow (Nash-Sutcliffe Coefficient = 0.77) and river temperatures (Nash-Sutcliffe Coefficient = 0.89) matched at downstream USGS gauge data well. A suite of model runs were made in combination with uniformly increased daily summer air temperatures by 2oC, 4 oC and 6 oC as well as adjusted precipitation by -40%, -30%, -20%, -10% and +10% as a sensitivity analysis to explore a broad range of potential future climates. We analyzed the summer stream temperatures and the percent of river length unsuitable for cold to warm water fish habitats. Impacts are greatest in large rivers due to the accumulation of river temperature warming throughout the entire river network. Cold water fish (i.e. brook trout) are most strongly affected while, warm water fish (i.e. largemouth bass) aren't expected to be impacted. The changes in stream temperatures under various potential climate scenarios will provide a better understanding of the specific impact that air temperature and precipitation have on aquatic thermal regimes and habitat.

  11. Monitor of the concentration of particles of dense radioactive materials in a stream of air

    DOEpatents

    Yule, Thomas J.

    1979-01-01

    A monitor of the concentration of particles of radioactive materials such as plutonium oxide in diameters as small as 1/2 micron includes in combination a first stage comprising a plurality of virtual impactors, a second stage comprising a further plurality of virtual impactors, a collector for concentrating particulate material, a radiation detector disposed near the collector to respond to radiation from collected material and means for moving a stream of air, possibly containing particulate contaminants, through the apparatus.

  12. Flow on Magnetizable Particles in Turbulent Air Streams. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Davey, K. R.

    1979-01-01

    The flow of magnetizable particles in a turbulent air stream in the presence of an imposed magnetic field and the phenomenon of drag reduction produced by the introduction of particles in turbulent boundary layer are investigated. The nature of the particle magnetic force is discussed and the inherent difference between electric and magnetic precipitation is considered. The incorporation of turbulent diffusion theory with an imposed magnetic migration process both with and without inertia effects is examined.

  13. Biofiltration of benzene contaminated air streams using compost-activated carbon filter media

    SciTech Connect

    Zhu, L.; Kocher, W.M.; Abumaizar, R.J.

    1998-12-31

    Three laboratory-scale biofilter columns were operated for 81 days to investigate the removal of benzene from a waste gas stream. The columns contain a mixture of yard waste and sludge compost as biomedia. Different amounts of granular activated carbon (GAC) are mixed with the compost in two of the three columns to evaluate the extent to which biofilter performance can be enhanced. The effects of different operating conditions on the performance of the removal of benzene from air were evaluated. More than 90% removal efficiency was observed for an influent benzene concentration of about 75 ppm and an air flow rate of 0.3 L/min. in all 3 columns under steady-state conditions. Under most cases of shock loading conditions, such as a sudden increase in the air flow rate, or the benzene concentration in the influent, the biofilters containing GAC provided higher removal efficiencies and more stable operation than the biofilter containing compost only.

  14. Prediction of the blowout of jet diffusion flames in a coflowing stream of air

    SciTech Connect

    Karbasi, M.; Wierzba, I.

    1995-12-31

    The blowout limits of a lifted diffusion flame in a coflowing stream of air are estimated using a simple model for extinction, for a range of fuels, jet diameters and co-flowing stream velocities. The proposed model uses a parameter which relates to the ratio of a time associated with the mixing processes in a turbulent jet to a characteristic chemical time. The Kolmogorov microscale of time is used as time scale in this model. It is shown that turbulent diffusion flames are quenched by excessive turbulence for a critical value of this parameter. The predicted blowout velocity of diffusion flames obtained using this model is in good agreement with the available experimental data.

  15. Direct calculation of acoustic streaming including the boundary layer phenomena in an ultrasonic air pump

    NASA Astrophysics Data System (ADS)

    Wada, Yuji; Koyama, Daisuke; Nakamura, Kentaro

    2012-05-01

    Direct finite difference fluid simulation of acoustic streaming on the fine-meshed three-dimensiona model by graphics processing unit (GPU)-oriented calculation array is discussed. Airflows due to the acoustic traveling wave are induced when an intense sound field is generated in a gap between a bending transducer and a reflector. Calculation results showed good agreement with the measurements in the pressure distribution. In addition to that, several flow-vortices were observed near the boundary of the reflector and the transducer, which have been often discussed in acoustic tube near the boundary, and have never been observed in the calculation in the ultrasonic air pump of this type.

  16. Air- and Stream-Water-Temperature Trends in the Chesapeake Bay Region, 1960-2014

    USGS Publications Warehouse

    Jastram, John D.; Rice, Karen C.

    2015-12-14

    The U.S. Environmental Protection Agency (EPA) uses indicators that “represent the state or trend of certain environmental or societal conditions … to track and better understand the effects of changes in the Earth’s climate” (U.S. Environmental Protection Agency, 2014). Updates to these indicators are published biennially by the EPA. The U.S. Geological Survey (USGS), in cooperation with the EPA, has completed analyses of air- and stream-water-temperature trends in the Chesapeake Bay region to be included as an indicator in a future release of the EPA report.

  17. Air- and Stream-Water-Temperature Trends in the Chesapeake Bay Region, 1960-2014

    USGS Publications Warehouse

    Jastram, John D.; Rice, Karen C.

    2015-01-01

    The U.S. Environmental Protection Agency (EPA) uses indicators that “represent the state or trend of certain environmental or societal conditions … to track and better understand the effects of changes in the Earth’s climate” (U.S. Environmental Protection Agency, 2014). Updates to these indicators are published biennially by the EPA. The U.S. Geological Survey (USGS), in cooperation with the EPA, has completed analyses of air- and stream-water-temperature trends in the Chesapeake Bay region to be included as an indicator in a future release of the EPA report.

  18. Mexico City air quality research initiative. Volume 2, Problem definition, background, and summary of prior research

    SciTech Connect

    Not Available

    1994-06-01

    Air pollution in Mexico City has increased along with the growth of the city, the movement of its population, and the growth of employment created by industry. The main cause of pollution in the city is energy consumption. Therefore, it is necessary to take into account the city`s economic development and its prospects when considering the technological relationships between well-being and energy consumption. Air pollution in the city from dust and other particles suspended in the air is an old problem. However, pollution as we know it today began about 50 years ago with the growth of industry, transportation, and population. The level of well-being attained in Mexico City implies a high energy use that necessarily affects the valley`s natural air quality. However, the pollution has grown so fast that the City must act urgently on three fronts: first, following a comprehensive strategy, transform the economic foundation of the city with nonpolluting activities to replace the old industries, second, halt pollution growth through the development of better technologies; and third, use better fuels, emission controls, and protection of wooded areas.

  19. Phase Segregation at the Liquid-Air Interface Prior to Liquid-Liquid Equilibrium.

    PubMed

    Bermúdez-Salguero, Carolina; Gracia-Fadrique, Jesús

    2015-08-13

    Binary systems with partial miscibility segregate into two liquid phases when their overall composition lies within the interval defined by the saturation points; out of this interval, there is one single phase, either solvent-rich or solute-rich. In most systems, in the one-phase regions, surface tension decreases with increasing solute concentration due to solute adsorption at the liquid-air interface. Therefore, the solute concentration at the surface is higher than in the bulk, leading to the hypothesis that phase segregation starts at the liquid-air interface with the formation of two surface phases, before the liquid-liquid equilibrium. This phenomenon is called surface segregation and is a step toward understanding liquid segregation at a molecular level and detailing the constitution of fluid interfaces. Surface segregation of aqueous binary systems of alkyl acetates with partial miscibility was theoretically demonstrated by means of a thermodynamic stability test based on energy minimization. Experimentally, the coexistence of two surface regions was verified through Brewster's angle microscopy. The observations were further interpreted with the aid of molecular dynamics simulations, which show the diffusion of the acetates from the bulk toward the liquid-air interface, where acetates aggregate into acetate-rich domains. PMID:26189700

  20. Experimental Investigation Evaporation of Liquid Mixture Droplets during Depressurization into Air Stream

    NASA Astrophysics Data System (ADS)

    Liu, L.; Bi, Q. C.; Terekhov, Victor I.; Shishkin, Nikolay E.

    2010-03-01

    The objective of this study is to develop experimental method to study the evaporation process of liquid mixture droplets during depressurization and into air stream. During the experiment, a droplet was suspended on a thermocouple; an infrared thermal imager was used to measure the droplet surface temperature transition. Saltwater droplets were used to investigate the evaporation process during depressurization, and volatile liquid mixtures of ethanol, methanol and acetone in water were applied to experimentally research the evaporation into air stream. According to the results, the composition and concentration has a complex influence on the evaporation rate and the temperature transition. With an increase in the share of more volatile component, the evaporation rate increases. While, a higher salt concentration in water results in a lower evaporation rate. The shape variation of saltwater droplet also depends on the mass concentration in solution, whether it is higher or lower than the eutectic point (22.4%). The results provide important insight into the complex heat and mass transfer of liquid mixture during evaporation.

  1. Liftoff and blowoff of a diffusion flame between parallel streams of fuel and air

    SciTech Connect

    Fernandez-Tarrazo, Eduardo; Vera, Marcos; Linan, Amable

    2006-01-01

    A numerical analysis is presented to describe the liftoff and blowoff of a diffusion flame in the mixing layer between two parallel streams of fuel (mainly methane diluted with nitrogen) and air emerging from porous walls. The analysis, which takes into account the effects of thermal expansion, assumes a one-step overall Arrhenius reaction, where the activation energy E is allowed to vary to reproduce the variations of the planar flame propagation velocity with the equivalence ratio. First, we describe the steady flame-front structure when stabilized close to the porous wall (attached flame regime). Then, we analyze the case where the flame front is located far away from the porous wall, at a distance x{sub f}' such that, upstream of the flame front, the mixing layer has a self-similar structure (lifted flame regime). For steady lifted flames, the results, given here in the case when the fuel and air streams are injected with the same velocity, relate U{sub f}'/S{sub L}, the front velocity (relative to the upstream flow) measured with the planar stoichiometric flame velocity, with the Damkohler number D{sub m}=({delta}{sub m}/{delta}{sub L}){sup 2}, based on the thickness, {delta}{sub m}, of the nonreacting mixing layer at the flame-front position and the laminar flame thickness, {delta}{sub L}. For large values of D{sub m}, the results, presented here for a wide range of dilutions of the fuel stream, provide values of the front propagation velocity that are in good agreement with previous experimental results, yielding well-defined conditions for blowoff. The calculated flame-front velocity can also be used to describe the transient flame-front dynamics after ignition by an external energy source.

  2. Magnetic Characterization of Stream-Sediments From Buenos Aires Province, Argentina, Affected by Pollution

    NASA Astrophysics Data System (ADS)

    Chaparro, M. A.; Sinito, A. M.; Bidegain, J. C.; Gogorza, C. S.; Jurado, S.

    2001-12-01

    A wide urban area from Northeast of Buenos Aires Province is exposed to an important anthropogenic influence, mainly due to industrial activity. In this two water streams were chosen: one of them (Del Gato stream, G) next to La Plata City and the another one (El Pescado stream, P) on the outskirts of the city. Both streams have similar characteristics, although the first one (G) has a higher input of pollutants (fluvial effluents, fly ashes, solid wastes, etc.) than the last one (P). Sediments analyzed in this work are limes from continental origin of PostPampeano (Holocene). Although, some cores were affected by sandy-limy sediments with mollusc valves from Querandino Sea (Pleistocene - later Holocene) and limy sediments of chestnut color with calcareous concretions from the Ensenadense. Magnetic measurements and geochemical studies were carried out on the samples. Among the magnetic parameters, specific susceptibility (X), X frequency-dependence (Xfd%), X temperature-dependence, Natural Remanent Magnetization (NRM), Isothermal Remanent Magnetization (IRM), Saturation IRM (SIRM), coercivity of remanence (Bcr), S ratio and SIRM/X ratio, Anhysteric Remanent Magnetization (ARM), Magnetic and Thermal Demagnetization were studied. The magnetic characteristics for both sites indicate the predominance of magnetically soft minerals on G site and relatively hard minerals on P site. Magnetite is the main magnetic carrier, Pseudo Single Domain and Single Domain grains were found. Chemical studies show (in some cases) a high concentration for some heavy metals (Pb, Cu, Zn, Ni and Fe) on the upper 22-cm. Contents of heavy metals and ARM were correlated. Very good correlation (R> 0.81) is found for Cu, Zn, Ni, Fe and the sum (of Pb, Cu, Zn and Ni), and a weaker correlation for Pb.

  3. Cave air and hydrological controls on prior calcite precipitation and stalagmite growth rates: Implications for palaeoclimate reconstructions using speleothems

    NASA Astrophysics Data System (ADS)

    Sherwin, Catherine M.; Baldini, James U. L.

    2011-07-01

    Hourly resolved cave air P and cave drip water hydrochemical data illustrate that calcite deposition on stalagmites can be modulated by prior calcite precipitation (PCP) on extremely short timescales. A very clear second-order covariation between cave air P and drip water Ca 2+ concentrations during the winter months demonstrates the effects of degassing-induced PCP on drip water chemistry. Estimating the strength of the cave air P control on PCP is possible because the PCP signal is so clear; at our drip site a one ppm shift in Ca 2+ concentrations requires a P shift of between 333 and 667 ppm. This value will undoubtedly vary from site to site, depending on drip water flow rate, residence time, drip water-cave air P differential, and availability of low P void spaces in the vadose zone above the cave. High-resolution cave environmental measurements were used to model calcite deposition on one stalagmite in Crag Cave, SW Ireland, and modelled growth over the study period (222 μm over 171 days) is extremely similar to the amount of actual calcite growth (240 μm) over the same time interval, strongly suggesting that equations used to estimate stalagmite growth rates are valid. Although cave air P appears to control drip water hydrochemistry in the winter, drip water dilution caused by rain events may have played a larger role during the summer, as evidenced by a series of sudden drops in Ca 2+ concentrations (dilution) followed by much more gradual increases in drip water Ca 2+ concentrations (slow addition of diffuse water). This research demonstrates that PCP on stalactites, cave ceilings, and void spaces within the karst above the cave partially controls drip water chemistry, and that thorough characterisation of this process at individual caves is necessary to most accurately interpret climate records from those sites.

  4. Decomposition of nitric oxide in a hot nitrogen stream to synthesize air for hypersonic wind tunnel combustion testing

    NASA Technical Reports Server (NTRS)

    Zumdieck, J. F.; Zlatarich, S. A.

    1974-01-01

    A clean source of high enthalpy air was obtained from the exothermic decomposition of nitric oxide in the presence of strongly heated nitrogen. A nitric oxide jet was introduced into a confined coaxial nitrogen stream. Measurements were made of the extent of mixing and reaction. Experimental results are compared with one- and two-dimensional chemical kinetics computations. Both analyses predict much lower reactivity than was observed experimentally. Inlet nitrogen temperatures above 2400 K were sufficient to produce experimentally a completely reacted gas stream of synthetic air.

  5. Real-time dissemination of air quality information using data streams and Web technologies: linking air quality to health risks in urban areas.

    PubMed

    Davila, Silvije; Ilić, Jadranka Pečar; Bešlić, Ivan

    2015-06-01

    This article presents a new, original application of modern information and communication technology to provide effective real-time dissemination of air quality information and related health risks to the general public. Our on-line subsystem for urban real-time air quality monitoring is a crucial component of a more comprehensive integrated information system, which has been developed by the Institute for Medical Research and Occupational Health. It relies on a StreamInsight data stream management system and service-oriented architecture to process data streamed from seven monitoring stations across Zagreb. Parameters that are monitored include gases (NO, NO2, CO, O3, H2S, SO2, benzene, NH3), particulate matter (PM10 and PM2.5), and meteorological data (wind speed and direction, temperature and pressure). Streamed data are processed in real-time using complex continuous queries. They first go through automated validation, then hourly air quality index is calculated for every station, and a report sent to the Croatian Environment Agency. If the parameter values exceed the corresponding regulation limits for three consecutive hours, the web service generates an alert for population groups at risk. Coupled with the Common Air Quality Index model, our web application brings air pollution information closer to the general population and raises awareness about environmental and health issues. Soon we intend to expand the service to a mobile application that is being developed. PMID:26110480

  6. Rising air and stream-water temperatures in Chesapeake Bay region, USA

    USGS Publications Warehouse

    Rice, Karen C.; Jastram, John D.

    2015-01-01

    Monthly mean air temperature (AT) at 85 sites and instantaneous stream-water temperature (WT) at 129 sites for 1960–2010 are examined for the mid-Atlantic region, USA. Temperature anomalies for two periods, 1961–1985 and 1985–2010, relative to the climate normal period of 1971–2000, indicate that the latter period was statistically significantly warmer than the former for both mean AT and WT. Statistically significant temporal trends across the region of 0.023 °C per year for AT and 0.028 °C per year for WT are detected using simple linear regression. Sensitivity analyses show that the irregularly sampled WT data are appropriate for trend analyses, resulting in conservative estimates of trend magnitude. Relations between 190 landscape factors and significant trends in AT-WT relations are examined using principal components analysis. Measures of major dams and deciduous forest are correlated with WT increasing slower than AT, whereas agriculture in the absence of major dams is correlated with WT increasing faster than AT. Increasing WT trends are detected despite increasing trends in streamflow in the northern part of the study area. Continued warming of contributing streams to Chesapeake Bay likely will result in shifts in distributions of aquatic biota and contribute to worsened eutrophic conditions in the bay and its estuaries.

  7. Jet Stream Converges Prior to 6.8M Niigata Chuetsu-oki Earthquake of Japan on 2007/07/16

    NASA Astrophysics Data System (ADS)

    Wu, H.

    2007-12-01

    The 6.8M Niigata Chuetsu-oki earthquake occurred on 2007/07/16 and resulted in 11 deaths and at least 1000 injuries have been reported, and 342 buildings were completely destroyed. The 108km/hr isobar jet stream line converged around an epicenter on 2007/07/01 12:00 and 2007/07/02 06:00. Before a devastating earthquake occurs, the underground water level usually changes caused by the rock squishing or loosening. This study assumed that rock squishing or loosening caused air inhalation or exhalation that creates an internal gravity wave. This phenomenon will change the jet streams at an altitude of 10 km. Ps. The predicted Data:07/06/26-07/07/26 Japan(37.4N140.0E)M 6.0 100% The Actual Data: 07/07/16 Japan (37.576N138.469E) 6.6M 10km This earthquake prediction had been predicted on http://tw.myblog.yahoo.com/wu10002002/ and sent to Dr. Dimitar Ouzounov in advance.

  8. Sampling of air streams and incorporation of samples in the Microtox{trademark} toxicity testing system

    SciTech Connect

    Kleinheinz, G.T.; St. John, W.P.

    1997-10-01

    A study was conducted to develop a rapid and reliable method for the collection and incorporation of biofiltration air samples containing volatile organic compounds (VOCs) into the Microtox toxicity testing system. To date, no method exists for this type of assay. A constant stream of VOCs was generated by air stripping compounds from a complex mixture of petroleum hydrocarbons (PHCs). Samples were collected on coconut charcoal ORBO tubes and the VOCs extracted with methylene chloride. The compounds extracted were then solvent exchanged into dimethyl sulfoxide (DMSO) under gaseous nitrogen. The resulting DMSO extract was directly incorporated into the Microtox toxicity testing system. In order to determine the efficiency of the solvent exchange, the VOCs in the DMSO extract were then extracted into hexane and subsequently analyzed using gas chromatography (GC) with a flame ionization detector (FID). It was determined that all but the most volatile VOCs could be effectively transferred from the ORBO tubes to DMSO for Microtox testing. Potential trace amounts of residual methylene chloride in the DMSO extracts showed no adverse effects in the Microtox system when compared to control samples.

  9. A hierarchical model of daily stream temperature using air-water temperature synchronization, autocorrelation, and time lags.

    PubMed

    Letcher, Benjamin H; Hocking, Daniel J; O'Neil, Kyle; Whiteley, Andrew R; Nislow, Keith H; O'Donnell, Matthew J

    2016-01-01

    Water temperature is a primary driver of stream ecosystems and commonly forms the basis of stream classifications. Robust models of stream temperature are critical as the climate changes, but estimating daily stream temperature poses several important challenges. We developed a statistical model that accounts for many challenges that can make stream temperature estimation difficult. Our model identifies the yearly period when air and water temperature are synchronized, accommodates hysteresis, incorporates time lags, deals with missing data and autocorrelation and can include external drivers. In a small stream network, the model performed well (RMSE = 0.59°C), identified a clear warming trend (0.63 °C decade(-1)) and a widening of the synchronized period (29 d decade(-1)). We also carefully evaluated how missing data influenced predictions. Missing data within a year had a small effect on performance (∼0.05% average drop in RMSE with 10% fewer days with data). Missing all data for a year decreased performance (∼0.6 °C jump in RMSE), but this decrease was moderated when data were available from other streams in the network. PMID:26966662

  10. A hierarchical model of daily stream temperature using air-water temperature synchronization, autocorrelation, and time lags

    USGS Publications Warehouse

    Letcher, Benjamin; Hocking, Daniel; O'Neill, K.; Whiteley, Andrew R.; Nislow, Keith H.; O'Donnell, Matthew

    2016-01-01

    Water temperature is a primary driver of stream ecosystems and commonly forms the basis of stream classifications. Robust models of stream temperature are critical as the climate changes, but estimating daily stream temperature poses several important challenges. We developed a statistical model that accounts for many challenges that can make stream temperature estimation difficult. Our model identifies the yearly period when air and water temperature are synchronized, accommodates hysteresis, incorporates time lags, deals with missing data and autocorrelation and can include external drivers. In a small stream network, the model performed well (RMSE = 0.59 °C), identified a clear warming trend (0.63 °C · decade-1) and a widening of the synchronized period (29 d · decade-1). We also carefully evaluated how missing data influenced predictions. Missing data within a year had a small effect on performance (~ 0.05% average drop in RMSE with 10% fewer days with data). Missing all data for a year decreased performance (~ 0.6 °C jump in RMSE), but this decrease was moderated when data were available from other streams in the network.

  11. A hierarchical model of daily stream temperature using air-water temperature synchronization, autocorrelation, and time lags

    PubMed Central

    Hocking, Daniel J.; O’Neil, Kyle; Whiteley, Andrew R.; Nislow, Keith H.; O’Donnell, Matthew J.

    2016-01-01

    Water temperature is a primary driver of stream ecosystems and commonly forms the basis of stream classifications. Robust models of stream temperature are critical as the climate changes, but estimating daily stream temperature poses several important challenges. We developed a statistical model that accounts for many challenges that can make stream temperature estimation difficult. Our model identifies the yearly period when air and water temperature are synchronized, accommodates hysteresis, incorporates time lags, deals with missing data and autocorrelation and can include external drivers. In a small stream network, the model performed well (RMSE = 0.59°C), identified a clear warming trend (0.63 °C decade−1) and a widening of the synchronized period (29 d decade−1). We also carefully evaluated how missing data influenced predictions. Missing data within a year had a small effect on performance (∼0.05% average drop in RMSE with 10% fewer days with data). Missing all data for a year decreased performance (∼0.6 °C jump in RMSE), but this decrease was moderated when data were available from other streams in the network. PMID:26966662

  12. Aerodynamic heating and the deflection of drops by an obstacle in an air stream in relation to aircraft icing

    NASA Technical Reports Server (NTRS)

    Kantrowitz, Arthur

    1940-01-01

    Two topics of interest to persons attempting to apply the heat method of preventing ice formation on aircraft are considered. Surfaces moving through air at high speed are shown, both theoretically and experimentally, to be subject to important aerodynamic heating effects that will materially reduce the heat required to prevent ice. Numerical calculations of the path of water drops in an air stream around a circular cylinder are given. From these calculations, information is obtained on the percentage of the swept area cleared of drops.

  13. Removal of volatile organic compounds from air streams by making use of a microwave plasma burner with reverse vortex flows

    NASA Astrophysics Data System (ADS)

    Kim, Ji H.; Ma, Suk H.; Cho, Chang H.; Hong, Yong C.; Ahn, Jae Y.

    2014-01-01

    We developed an atmospheric-pressure microwave plasma burner for removing volatile organic compounds (VOCs) from polluted air streams. This study focused on the destruction of the VOCs in the high flow rate polluted streams required for industrial use. Plasma flames were sustained by injecting liquefied natural gas (LNG), which is composed of CH4, into the microwave plasma torch. With its high temperature and high density of atomic oxygen, the microwave torch attained nearly complete combustion of LNG, thereby providing a large-volume, high-temperature plasma flame. The plasma flame was applied to reactors in which the polluted streams were in one of two vortex flows: a conventional vortex reactor (CVR) or a reverse vortex reactor (RVR). The RVR, using a plasma power of 2 kW and an LNG flow of 20 liters per minute achieved a destruction removal efficiency (DRE) of 98% for an air flow rate of 5 Nm3/min polluted with 550 pm of VOCs.. For the same experimental parameters, the CVR provided a DRE of 90.2%. We expect that this decontamination system will prove effective in purifying contaminated air at high flow rates.

  14. Decomposition of benzene and toluene in air streams in fixed-film photoreactors coated with TiO2 catalyst.

    PubMed

    Ku, Young; Chen, Juan-Shiang; Chen, Hua-Wei

    2007-03-01

    The decomposition of benzene and toluene in air streams by UV/TiO2 process was studied in different annular photoreactors under various operating conditions. The shells of reactors used in this research are made of stainless steel, Pyrex glass, or titanium. The TiO2 film was coated to the inner surface of the reactors by either rotating coating or sol-gel techniques. The TiO2 films coated by sol-gel technique were found to be smoother and more uniform than those coated by rotating coating. However, experimental results indicated that the photocatalysis of benzene or toluene in a glass reactor with rotating-coated TiO2 film delivered higher decompositions in air streams than that with sol-gel coated reactors. Benzene and toluene were decomposed more effectively in a coated glass reactor than in a coated stainless steel reactor under the same operating conditions. The presence of water vapor in air-stream plays an important role in the decomposition of benzene and toluene, and a relative humidity of approximately 5-6% was found to be adequate. The presence of excessive amounts of humidity retarded the decomposition to certain extents possibly results from the competitive adsorption of water molecules on the active sites of TiO2.

  15. Three phase biological treatment process for chlorinated compounds in air streams

    SciTech Connect

    Parker, W.J.; Collins, J.; Wells, J.; Kennedy, K.

    1999-07-01

    A combination of experimental and modeling studies were carried out to evaluate the potential for biological treatment of air streams containing chlorinated organics in a hybrid process. The proposed process consists of a scrubbing column for transferring chlorinated compounds from the gas to the liquid phase and a high rate anaerobic reactor for biodegradation of the compounds. Carbon tetrachloride, tetrachloroethylene and dichloromethane were employed as target compounds in this study to assess compounds with a range of chemical, physical and biological properties. Batch tests provided conclusive evidence that the target compounds strongly partition to vegetable oil. Continuous flow test results suggested that high removal efficiencies for all three compounds ({gt}90%) could be obtained with gas-liquid flow ratios less than 200. It was found that the Onda correlations did not fit the experimental data of vegetable oil very well, hence the Onda correlations were modified by assuming that the gas phase resistance was controlling mass transfer. The assumption appeared to be valid for the compounds with lower gas-oil partitioning coefficients (CT and PCE). DCM appeared to have some component of liquid phase control. Experiments were conducted in high rate anaerobic reactors to evaluate the impact of cosubstrate loading and hydraulic retention time on the biodegradation of the target compounds. Removals approached 100% for all three target compounds when the UASB was operated at high values of OLR and HRT. Removals for PCE and DCM decreased when the UASB was run under more strenuous conditions. A hybrid anaerobic reactor that consisted of a liquid-liquid mass transfer zone and an anaerobic biodegradation zone was operated to assess the processes potential to degrade the target compounds when they entered in a vegetable oil matrix.

  16. Impacts of cave air ventilation and in-cave prior calcite precipitation on Golgotha Cave dripwater chemistry, southwest Australia

    NASA Astrophysics Data System (ADS)

    Treble, Pauline C.; Fairchild, Ian J.; Griffiths, Alan; Baker, Andy; Meredith, Karina T.; Wood, Anne; McGuire, Elizabeth

    2015-11-01

    Speleothem trace element chemistry is an important component of multi-proxy records of environmental change but a thorough understanding of hydrochemical processes is essential for its interpretation. We present a dripwater chemistry dataset (PCO2, alkalinity, Ca, SIcc, Mg and Sr) from an eight-year monitoring study from Golgotha Cave, building on a previous study of hydrology and dripwater oxygen isotopes (Treble et al., 2013). Golgotha Cave is developed in Quaternary aeolianite and located in a forested catchment in the Mediterranean-type climate of southwest Western Australia. All dripwaters from each of the five monitored sites become supersaturated with respect to calcite during most of the year when cave ventilation lowers PCO2 in cave air. In this winter ventilation mode, prior calcite precipitation (PCP) signals of increased Mg/Ca and Sr/Ca in dripwater are attributed to stalactite deposition. A fast-dripping site displays less-evolved carbonate chemistry, implying minimal stalactite growth, phenomena which are attributed to minimal degassing because of the short drip interval (30 s). We employ hydrochemical mass-balance modelling techniques to quantitatively investigate the impact of PCP and CO2 degassing on our dripwater. Initially, we reverse-modelled dripwater solutions to demonstrate that PCP is dominating the dripwater chemistry at our low-flow site and predict that PCP becomes enhanced in underlying stalagmites. Secondly, we forward-modelled the ranges of solution Mg/Ca variation that potentially can be caused by degassing and calcite precipitation to serve as a guide to interpreting the resulting stalagmite chemistry. We predict that stalagmite trace element data from our high-flow sites will reflect trends in original dripwater solutes, preserving information on biogeochemical fluxes within our system. By contrast, stalagmites from our low-flow sites will be dominated by PCP effects driven by cave ventilation. Our poorly karstified system allows us

  17. U.S. Armed Forces air crew: incident illness and injury diagnosis during the 12 months prior to retirement, 2003-2012.

    PubMed

    Smallman, Darlene P; Hu, Zheng; Rohrbeck, Patricia

    2014-05-01

    U.S. Armed Services retirees are eligible for disability compensation for medical illness/injury incurred during their service. This analysis of recently retired U.S. active component air crew/aviation service members from all Services evaluated incident diagnoses among aviation retirees during the 12 months prior to retirement and assessed trends in first-time diagnoses by major diagnostic category and aviation component stratification. Most aviation retirees were in their 40s, Air Force, male, white, and senior officers and warrant officers. Among the study population, 14,191 (88%) of aviation retirees had at least one first-time diagnosis recorded during the 12 months prior to retirement. During 2003-2012, 63.8% of all diagnoses in aviation retirees during the 12 months prior to retirement were new. The highest proportions of new diagnoses were for "other disorders of the ear," "organic sleep disorders," and "general symptoms." Among the four subtypes of aviators, general air crew/air craft crew had the lowest proportion of new diagnoses (60.2%). PMID:24885877

  18. Enhancing biochar yield by co-pyrolysis of bio-oil with biomass: impacts of potassium hydroxide addition and air pretreatment prior to co-pyrolysis.

    PubMed

    Veksha, Andrei; Zaman, Waheed; Layzell, David B; Hill, Josephine M

    2014-11-01

    The influence of KOH addition and air pretreatment on co-pyrolysis (600 °C) of a mixture of bio-oil and biomass (aspen wood) was investigated with the goal of increasing biochar yield. The bio-oil was produced as a byproduct of the pyrolysis of biomass and recycled in subsequent runs. Co-pyrolysis of the biomass with the recycled bio-oil resulted in a 16% mass increase in produced biochar. The yields were further increased by either air pretreatment or KOH addition prior to co-pyrolysis. Air pretreatment at 220 °C for 3 h resulted in the highest mass increase (32%) compared to the base case of pyrolysis of biomass only. No synergistic benefit was observed by combining KOH addition with air pretreatment. In fact, KOH catalyzed reactions that increased the bed temperature resulting in carbon loss via formation of CO and CO2.

  19. The use of warm air stream for solvent evaporation: effects on the durability of resin-dentin bonds.

    PubMed

    Reis, Alessandra; Klein-Júnior, Celso A; de Souza, Fabio H Coelho; Stanislawczuk, Rodrigo; Loguercio, Alessandro D

    2010-01-01

    This study evaluated the effect of a warm (W) or cold (C) air-dry stream for solvent evaporation on the immediate (IM) and six-month (6M) resin-dentin bond strength (microTBS) and silver nitrate uptake pattern (SNU) of two-step etch-and-rinse adhesive system (Adper Single Bond [SB] and Prime & Bond 2.1 [PB]). The adhesives were applied on demineralized dentin surfaces and a warm or cold air-dry stream (10 seconds) was applied followed by light-activation (10 seconds). After 24-hours of water storage, the specimens were serially sectioned in the "x" and "y" directions to obtain bonded sticks around 0.8 mm2 to be tested immediately or after six months of water storage. The specimens at each period were immersed in a 50% solution of silver nitrate, photodeveloped and analyzed by SEM for SNU. Higher IM microTBS values were observed for SB under W conditions. Both adhesives showed reductions in microTBS after 6M in both air temperatures. Regarding SEM, a low silver nitrate uptake was observed in the W groups either in IM or 6M for both adhesives. PMID:20166408

  20. Land use effect on invertebrate assemblages in Pampasic streams (Buenos Aires, Argentina).

    PubMed

    Solis, Marina; Mugni, Hernán; Hunt, Lisa; Marrochi, Natalia; Fanelli, Silvia; Bonetto, Carlos

    2016-09-01

    Agriculture and livestock may contribute to water quality degradation in adjacent waterbodies and produce changes in the resident invertebrate composition. The objective of the present study was to assess land use effects on the stream invertebrate assemblages in rural areas of the Argentine Pampa. The four sampling events were performed at six sites in four streams of the Pampa plain; two streams were sampled inside a biosphere reserve, and another one was surrounded by extensive livestock fields. The fourth stream was sampled at three sites; the upstream site was adjacent to agricultural plots, the following site was adjacent to an intensive livestock plot and the downstream site was adjacent to extensive breeding cattle plots. Higher pesticide concentrations were found at the site adjacent to agricultural plots and higher nutrient concentrations at the sites adjacent to agricultural and intensive breeding cattle plots. The invertebrate fauna were also different at these sites. Multivariate analysis showed a relationship between nutrient concentrations and taxonomic composition. Amphipoda (Hyalella curvispina) was the dominant group in the reserve and extensive breeding cattle sites, but was not present in the agricultural site. Also, Chironomidae were absent from the agricultural site while present at other sites. Gasteropoda (Biomphalaria peregrina), Zygoptera, and Hirudinea were dominant at the most impacted agricultural and intensive breeding cattle sites. PMID:27581006

  1. SST, Winds, and Air-Sea Fluxes in the Gulf Stream Region in the First Winter of CLIMODE

    NASA Astrophysics Data System (ADS)

    Kelly, K. A.; Dickinson, S.; Jones, H. R.

    2006-12-01

    The NSF sponsored CLIvar MOde Water Dynamic Experiment (CLIMODE) focuses on the wintertime processes responsible for the formation and dispersal of Eighteen Degree Water (EDW), the subtropical mode water of the North Atlantic. This region has the largest wintertime loss of heat from the ocean to the atmosphere, made possible by the influx of heat from the Gulf Stream (GS). These fluxes fuel the formation and intensification of storms, as cool, dry continental air encounters the warm boundary current waters. The actual impact of the large transfers of heat on the ocean and on the atmosphere are likely underestimated in weather and climate models, owing to poor observational input and inaccurate boundary layer physics. Several new sources of data are available with which to examine the relationship between the Gulf Stream, air-sea heat fluxes, winds, and storms: wind vector and SST measurements from satellites, as well as in situ measurements, including data from CLIMODE. Improved satellite data includes the ocean vector winds from QuikSCAT, re-processed at a spatial resolution of 12.5km, and microwave SST from AMSR-E. Although the microwave resolution is coarser than for infrared SST, the ability of microwave sensors to see through clouds gives better effective resolution of SST, particularly during storms. Two CLIMODE cruises were conducted in the winter of 2005-2006. During the first cruise in November 2005, SST dropped by about 1.5-2C, leaving SST in the recirculation region at about 22C. By the start of the second cruise in January 2006, SST had fallen to 20C near the GS core, and 19C in the mode water region. By the end of the second cruise 2 weeks later, the region of 20C water had dropped to 19C, suggesting that EDW formation was imminent. SST in the mode water region reached 18C the following week. Maximum wind speeds were distinctly centered on the GS warm core for much of January 2006. Recent studies suggest that the Gulf Stream could affect the storm

  2. Removal of volatile organics from humidified air streams by absorption. Final report, July 1985-March 1987

    SciTech Connect

    Coutant, R.W.; Zwick, T.; Kim, B.C.

    1987-12-01

    The Air Force frequently relies on air-stripping technologies to remove organic chemicals from ground waters contaminated from fuel and solvent spills. Although air stripping is extremely efficient at removing contaminants from the groundwater, these contaminants are only transferred into the air and in several states, air pollution controls are also required. Activated-carbon beds are one potential emissions control under study. The objective of this study was to determine the effects of contaminant concentration, humidity, and chemical competition on the sorption performance of activated carbons. Based on laboratory results, a preliminary cost comparison was made for heated and unheated carbon beds. Volatile organics of interest included benzene, ethyl benzene, toluene, xylenes. trichloroethylene, and 1,1-dichloroethylene.

  3. Short-term Effects of Ambient Air Pollution on Emergency Department Visits for Asthma: An Assessment of Effect Modification by Prior Allergic Disease History

    PubMed Central

    Sohn, Jungwoo; Cho, Jaelim; Cho, Seong-Kyung; Choi, Yoon Jung; Shin, Dong Chun

    2016-01-01

    Objectives The goal of this study was to investigate the short-term effect of ambient air pollution on emergency department (ED) visits in Seoul for asthma according to patients’ prior history of allergic diseases. Methods Data on ED visits from 2005 to 2009 were obtained from the Health Insurance Review and Assessment Service. To evaluate the risk of ED visits for asthma related to ambient air pollutants (carbon monoxide [CO], nitrogen dioxide [NO2], ozone [O3], sulfur dioxide [SO2], and particulate matter with an aerodynamic diameter <10 μm [PM10]), a generalized additive model with a Poisson distribution was used; a single-lag model and a cumulative-effect model (average concentration over the previous 1-7 days) were also explored. The percent increase and 95% confidence interval (CI) were calculated for each interquartile range (IQR) increment in the concentration of each air pollutant. Subgroup analyses were done by age, gender, the presence of allergic disease, and season. Results A total of 33 751 asthma attack cases were observed during the study period. The strongest association was a 9.6% increase (95% CI, 6.9% to 12.3%) in the risk of ED visits for asthma per IQR increase in O3 concentration. IQR changes in NO2 and PM10 concentrations were also significantly associated with ED visits in the cumulative lag 7 model. Among patients with a prior history of allergic rhinitis or atopic dermatitis, the risk of ED visits for asthma per IQR increase in PM10 concentration was higher (3.9%; 95% CI, 1.2% to 6.7%) than in patients with no such history. Conclusions Ambient air pollutants were positively associated with ED visits for asthma, especially among subjects with a prior history of allergic rhinitis or atopic dermatitis. PMID:27744674

  4. Role of amine structure on carbon dioxide adsorption from ultradilute gas streams such as ambient air.

    PubMed

    Didas, Stephanie A; Kulkarni, Ambarish R; Sholl, David S; Jones, Christopher W

    2012-10-01

    A fundamental study on the adsorption properties of primary, secondary, and tertiary amine materials is used to evaluate what amine type(s) are best suited for ultradilute CO(2) capture applications. A series of comparable materials comprised of primary, secondary, or tertiary amines ligated to a mesoporous silica support via a propyl linker are used to systematically assess the role of amine type. Both CO(2) and water adsorption isotherms are presented for these materials in the range relevant to CO(2) capture from ambient air and it is demonstrated that primary amines are the best candidates for CO(2) capture from air. Primary amines possess both the highest amine efficiency for CO(2) adsorption as well as enhanced water affinity compared to other amine types or the bare silica support. The results suggest that the rational design of amine adsorbents for the extraction of CO(2) from ambient air should focus on adsorbents rich in primary amines.

  5. [Mathematical modeling of the kinematics of a pilot's head while catapulting into an air stream].

    PubMed

    Kharchenko, V I; Golovleva, N V; Konakhevich, Iu G; Liapin, V A; Mar'in, A V

    1987-01-01

    The trajectories of head movements in the helmet and velocities of impact contact with the seat and anterior of the cockpit were calculated as applied to every stage of the catapulting process and mass-inertia parameters of helmets taken into account. Kinematic models were used to describe biomechanic parameters of the head-neck system. Special attention was given to the case of catapulting to the air flow. The effect upon the nod of aerodynamic forces acting on the human body and the catapult ejection seat at air flow velocities of 700-800 and 1300 km/hr was calculated. PMID:3586592

  6. Integrated air stream micromixer for performing bioanalytical assays on a plastic chip.

    PubMed

    Geissler, Matthias; Li, Kebin; Zhang, Xuefeng; Clime, Liviu; Robideau, Gregg P; Bilodeau, Guillaume J; Veres, Teodor

    2014-10-01

    This paper describes the design, functioning and use of an integrated mixer that relies on air flux to agitate microliter entities of fluid in an embedded microfluidic cavity. The system was fabricated from multiple layers of a thermoplastic elastomer and features circuits for both liquid and air supply along with pneumatic valves for process control. Internally-dyed polymer particles have been used to visualize flow within the fluid phase during agitation. Numerical modelling of the micromixer revealed an overall efficacy of 10(-1) to 10(-2) for momentum transfer at the air-water interface. Simulation of air vortex dynamics showed dependency of the flow pattern on the velocity of the flux entering the cavity. Three bioanalytical assays have been performed as proof-of-concept demonstrations. In a first assay, cells of Listeria monocytogenes were combined with magnetic nanoparticles (NPs), resulting in high-density coverage of the bacteria's surface with NPs after 1 min of agitation. This finding is contrasted by a control experiment without agitation for which interaction between bacteria and NPs remains low. In a second one, capture and release of genomic DNA from fungi through adsorption onto magnetic beads was tested and shown to be improved by agitation compared to non-agitated controls. A third assay finally involved fluorescently-labelled target oligonucleotide strands and polystyrene particles modified with DNA capture probes to perform detection of nucleic acids on beads. Excellent selectivity was obtained in a competitive hybridization process using a multiplexed micromixer chip design. PMID:25091476

  7. Heat fluxes and roll circulations over the western Gulf Stream during an intense cold-air outbreak

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Ferguson, Michael P.

    1991-01-01

    Turbulence and heat fluxes in the marine atmospheric boundary layer (MABL) for three aircraft stacks near the western Gulf Stream front, observed during the Genesis of Atlantic Lows Experiment (GALE) January 28, 1986 cold-air outbreak, has been studied using mixed-layer scaling. The GOES image and stability parameter indicates that these three stacks were in the roll vortex regime. The turbulence structure in the MABL is studied for this case, as well as the significance of roll vortices to heat fluxes. The roll circulations are shown to contribute significantly to the sensible (temperature) and latent heat (moisture) fluxes with importance increasing upward. The results suggest that the entrainment at the MABL top might affect the the budgets of temperature and humidity fluxes in the lower MABL, but not in the unstable surface layer.

  8. Use of thermal analysis techniques (TG-DSC) for the characterization of diverse organic municipal waste streams to predict biological stability prior to land application

    SciTech Connect

    Fernandez, Jose M.; Plaza, Cesar; Polo, Alfredo; Plante, Alain F.

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Thermal analysis was used to assess stability and composition of organic matter in three diverse municipal waste streams. Black-Right-Pointing-Pointer Results were compared with C mineralization during 90-day incubation, FTIR and {sup 13}C NMR. Black-Right-Pointing-Pointer Thermal analysis reflected the differences between the organic wastes before and after the incubation. Black-Right-Pointing-Pointer The calculated energy density showed a strong correlation with cumulative respiration. Black-Right-Pointing-Pointer Conventional and thermal methods provide complimentary means of characterizing organic wastes. - Abstract: The use of organic municipal wastes as soil amendments is an increasing practice that can divert significant amounts of waste from landfill, and provides a potential source of nutrients and organic matter to ameliorate degraded soils. Due to the high heterogeneity of organic municipal waste streams, it is difficult to rapidly and cost-effectively establish their suitability as soil amendments using a single method. Thermal analysis has been proposed as an evolving technique to assess the stability and composition of the organic matter present in these wastes. In this study, three different organic municipal waste streams (i.e., a municipal waste compost (MC), a composted sewage sludge (CS) and a thermally dried sewage sludge (TS)) were characterized using conventional and thermal methods. The conventional methods used to test organic matter stability included laboratory incubation with measurement of respired C, and spectroscopic methods to characterize chemical composition. Carbon mineralization was measured during a 90-day incubation, and samples before and after incubation were analyzed by chemical (elemental analysis) and spectroscopic (infrared and nuclear magnetic resonance) methods. Results were compared with those obtained by thermogravimetry (TG) and differential scanning calorimetry (DSC

  9. Morphological classification of low viscosity drop bag breakup in a continuous air jet stream

    NASA Astrophysics Data System (ADS)

    Zhao, Hui; Liu, Hai-Feng; Li, Wei-Feng; Xu, Jian-Liang

    2010-11-01

    To investigate the effect of Rayleigh-Taylor wave number in the region of maximum cross stream dimension (NRT) on drop breakup morphology, the breakup properties of accelerating low viscosity liquid drops (water and ethanol drops, diameter=1.2-6.6 mm, Weber number=10-80) were investigated using high-speed digital photography. The results of morphological analysis show a good correlation of the observed breakup type with NRT; bag breakup occurred when NRT was 1/√3 -1, bag-stamen breakup at 1-2, and dual-bag breakup at 2-3. The number of nodes in bag breakup, bag-stamen breakup, and dual-bag breakup all increased with Weber number. The experimental results are consistent with the model estimates and in good agreement with those reported in the literature.

  10. Numerical Investigation of Hydrogen and Kerosene Combustion in Supersonic Air Streams

    NASA Technical Reports Server (NTRS)

    Taha, A. A.; Tiwari, S. N.; Mohieldin, T. O.

    1999-01-01

    The effect of mixing schemes on the combustion of both gaseous hydrogen and liquid kerosene is investigated. Injecting pilot gaseous hydrogen parallel to the supersonic incoming air tends to maintain the stabilization of the main liquid kerosene, which is normally injected. Also the maximum kerosene equivalence ratio that can maintain stable flame can be increased by increasing the pilot energy level. The wedge flame holding contributes to an increased kerosene combustion efficiency by the generation of shock-jet interaction.

  11. Travel of the center of pressure of airfoils transversely to the air stream

    NASA Technical Reports Server (NTRS)

    Katzmayr, Richard

    1929-01-01

    The experiments here described were performed for the purpose of obtaining the essential facts concerning the distribution of the air force along the span. We did not follow, however, the time-consuming method of point-to-point measurements of the pressure distribution on the wing surfaces, but determined directly the moment of mean force about an axis passing through the middle of the span parallel to the direction of flight.

  12. Electrical impedance tomography to evaluate air distribution prior to extubation in very-low-birth-weight infants: a feasibility study

    PubMed Central

    de Souza Rossi, Felipe; Yagui, Ana Cristina Zanon; Haddad, Luciana Branco; Deutsch, Alice D'Agostini; Rebello, Celso Moura

    2013-01-01

    OBJECTIVES: Nasal continuous positive airway pressure is used as a standard of care after extubation in very-low-birth-weight infants. A pressure of 5 cmH2O is usually applied regardless of individual differences in lung compliance. Current methods for evaluation of lung compliance and air distribution in the lungs are thus imprecise for preterm infants. This study used electrical impedance tomography to determine the feasibility of evaluating the positive end-expiratory pressure level associated with a more homogeneous air distribution within the lungs before extubation. METHODS: Ventilation homogeneity was defined by electrical impedance tomography as the ratio of ventilation between dependent and non-dependent lung areas. The best ventilation homogeneity was achieved when this ratio was equal to 1. Just before extubation, decremental expiratory pressure levels were applied (8, 7, 6 and 5 cmH20; 3 minutes each step), and the pressure that determined the best ventilation homogeneity was defined as the best positive end-expiratory pressure. RESULTS: The best positive end-expiratory pressure value was 6.3±1.1 cmH20, and the mean continuous positive airway pressure applied after extubation was 5.2±0.4 cmH20 (p = 0.002). The extubation failure rate was 21.4%. X-Ray and blood gases after extubation were also checked. CONCLUSION: This study demonstrates that electrical impedance tomography can be safely and successfully used in patients ready for extubation to suggest the best ventilation homogeneity, which is influenced by the level of expiratory pressure applied. In this feasibility study, the best lung compliance was found with pressure levels higher than the continuous positive airway pressure levels that are usually applied for routine extubation. PMID:23644854

  13. Use of thermal analysis techniques (TG-DSC) for the characterization of diverse organic municipal waste streams to predict biological stability prior to land application.

    PubMed

    Fernández, José M; Plaza, César; Polo, Alfredo; Plante, Alain F

    2012-01-01

    The use of organic municipal wastes as soil amendments is an increasing practice that can divert significant amounts of waste from landfill, and provides a potential source of nutrients and organic matter to ameliorate degraded soils. Due to the high heterogeneity of organic municipal waste streams, it is difficult to rapidly and cost-effectively establish their suitability as soil amendments using a single method. Thermal analysis has been proposed as an evolving technique to assess the stability and composition of the organic matter present in these wastes. In this study, three different organic municipal waste streams (i.e., a municipal waste compost (MC), a composted sewage sludge (CS) and a thermally dried sewage sludge (TS)) were characterized using conventional and thermal methods. The conventional methods used to test organic matter stability included laboratory incubation with measurement of respired C, and spectroscopic methods to characterize chemical composition. Carbon mineralization was measured during a 90-day incubation, and samples before and after incubation were analyzed by chemical (elemental analysis) and spectroscopic (infrared and nuclear magnetic resonance) methods. Results were compared with those obtained by thermogravimetry (TG) and differential scanning calorimetry (DSC) techniques. Total amounts of CO(2) respired indicated that the organic matter in the TS was the least stable, while that in the CS was the most stable. This was confirmed by changes detected with the spectroscopic methods in the composition of the organic wastes due to C mineralization. Differences were especially pronounced for TS, which showed a remarkable loss of aliphatic and proteinaceous compounds during the incubation process. TG, and especially DSC analysis, clearly reflected these differences between the three organic wastes before and after the incubation. Furthermore, the calculated energy density, which represents the energy available per unit of organic

  14. A model for treating polluted air streams in a continuous two liquid phase stirred tank bioreactor.

    PubMed

    Fazaelipoor, Mohammad Hassan

    2007-09-01

    Biological air treatment systems have been widely under investigation in recent years. Inclusion of non-biodegradable organic solvents to these systems is a way to improve the biotic removal capacity of the systems. In this article the process of absorption and biodegradation of a hydrophobic organic compound in a two liquid phase stirred tank bioreactor has been modeled. Using the model it has been shown that the inclusion of an organic solvent is advantageous if certain conditions are met. Some simulation examples showed that the usefulness of adding an organic solvent to the system depends on kinetic parameters of biological reactions and mass transfer coefficients of pollutants and oxygen between the air and liquid phases. Since different factors influence the process, the usefulness of including an organic solvent to the system should be checked in each special case. The simple model presented in this article can help the prediction of the effect of amending a solvent to the bioreactor under a set of given conditions.

  15. Effect of prior dust collection on detection, counting efficiency, and energy resolution for alpha continuous air monitors

    SciTech Connect

    Newton, G.J.; Hoover, M.D.

    1994-11-01

    For the past several years, we have supported the DOE Waste Isolation Pilot Plant (WIPP) project by evaluating the capabilities and performance of the Eberline Alpha 6 continuous air monitor (CAM). This evalution has focused on the ability of the CAM to correctly report plutonium in the presence of salt dust. Tests involving the simultaneous collection of plutonium and salt have shown that burial by salt can degrade the detection of plutonium, but that this interference is negligible when salt concentrations are below about 0.2 mg/m{sup 3}. Throughout the evalution, it has been assumed that salt burial is a concern for slow, chronic release of plutonium, but that any acute release of plutonium would be collected on the top surface of the filter or salt and would be unattenuated. The spectral quality of alpha radiation detection on membrane filters is observed to improve with filter loading. This is attributed to the probability that accumulations of dust tend to fill in surface irregularities of the collection filter at a a faster rate than they create additional surface irregularities. The validity of these assumptions about the improved detection of plutonium on salt-layer surfaces has recently been questioned. Based on electron micrographic examination of salt-laden filters, it has been speculated that collection of salt dust on a membrane filter results in formation of pores, fissures, and dendritic shapes of salt on the filter surface. If plutonium were collected, particles could penetrate into the pores and fissures, resulting in a degraded or lost signal from the plutonium. Because no experimental evidence existed to answer the concern, the purpose of the current study was to quantify any differences between detection of plutonium on clean or salt-laden filters.

  16. Noise reduction evaluation of grids in a supersonic air stream with application to Space Shuttle

    NASA Technical Reports Server (NTRS)

    Seiner, J. M.; Manning, J. C.; Nystrom, P.; Pao, S. P.

    1977-01-01

    Near field acoustic measurements were obtained for a model supersonic air jet perturbed by a screen. Noise reduction potential in the vicinity of the space shuttle vehicle during ground launch when the rocket exhaust flow is perturbed by a grid was determined. Both 10 and 12 mesh screens were utilized for this experiment, and each exhibited a noise reduction only at very low frequencies in the near field forward arc. A power spectrum analysis revealed that a modest reduction of from 3 to 5 decibels exists below a Strouhal number S sub t = 0.11. Above S sub t = 0.11 screen harmonics increased the observed sound pressure level. The favorable noise reductions obtained with screens for S sub t 0.11 may be of substantial interest for the space shuttle at ground launch.

  17. Needs and workflow assessment prior to implementation of a digital pathology infrastructure for the US Air Force Medical Service

    PubMed Central

    Ho, Jonhan; Aridor, Orly; Glinski, David W.; Saylor, Christopher D.; Pelletier, Joseph P.; Selby, Dale M.; Davis, Steven W.; Lancia, Nicholas; Gerlach, Christopher B.; Newberry, Jonathan; Anthony, Leslie; Pantanowitz, Liron; Parwani, Anil V.

    2013-01-01

    Background: Advances in digital pathology are accelerating integration of this technology into anatomic pathology (AP). To optimize implementation and adoption of digital pathology systems within a large healthcare organization, initial assessment of both end user (pathologist) needs and organizational infrastructure are required. Contextual inquiry is a qualitative, user-centered tool for collecting, interpreting, and aggregating such detailed data about work practices that can be employed to help identify specific needs and requirements. Aim: Using contextual inquiry, the objective of this study was to identify the unique work practices and requirements in AP for the United States (US) Air Force Medical Service (AFMS) that had to be targeted in order to support their transition to digital pathology. Subjects and Methods: A pathology-centered observer team conducted 1.5 h interviews with a total of 24 AFMS pathologists and histology lab personnel at three large regional centers and one smaller peripheral AFMS pathology center using contextual inquiry guidelines. Findings were documented as notes and arranged into a hierarchal organization of common themes based on user-provided data, defined as an affinity diagram. These data were also organized into consolidated graphic models that characterized AFMS pathology work practices, structure, and requirements. Results: Over 1,200 recorded notes were grouped into an affinity diagram composed of 27 third-level, 10 second-level, and five main-level (workflow and workload distribution, quality, communication, military culture, and technology) categories. When combined with workflow and cultural models, the findings revealed that AFMS pathologists had needs that were unique to their military setting, when compared to civilian pathologists. These unique needs included having to serve a globally distributed patient population, transient staff, but a uniform information technology (IT) structure. Conclusions: The contextual

  18. Tailored synthesis of nanostructures by laser irradiation of a precursor microdroplet stream in open-air.

    PubMed

    Palanco, S; Marino, S; Gabás, M; Ayala, L; Ramos-Barrado, J R

    2015-01-14

    A method to synthesize multicomponent nanostructures in open-air is presented. A microdroplet precursor target is irradiated with a nanosecond laser pulse to induce plasma. At low droplet dispensing rates, the precursor and solvent are fully atomized without debris to produce nanoparticles and nanofilaments during plasma cooling. More complex structures like nanolayers or nanofoams can be synthetised at kilohertz droplet dispensing rates as additional droplets in the vicinity of the target droplet are subjected to the laser-induced plasma and its associated shockwave. Examples of both low- and fast-rate mechanisms are presented for Mn-Fe bi-metal oxide nanoparticles and zinc oxide nanoparticles, nanofilaments and nanofoams. Real-time diagnostics were carried out with time-resolved imaging, atomic emission spectroscopy, light scattering and shadowgraphy. In addition to overcoming some of the difficulties associated with pulsed-laser deposition (PLD), the use of a liquid precursor whose composition can be tailored on a droplet-to-droplet basis opens a number of possibilities.

  19. Using memory for prior aircraft events to detect conflicts under conditions of proactive air traffic control and with concurrent task requirements.

    PubMed

    Bowden, Vanessa K; Loft, Shayne

    2016-06-01

    In 2 experiments we examined the impact of memory for prior events on conflict detection in simulated air traffic control under conditions where individuals proactively controlled aircraft and completed concurrent tasks. Individuals were faster to detect conflicts that had repeatedly been presented during training (positive transfer). Bayesian statistics indicated strong evidence for the null hypothesis that conflict detection was not impaired for events that resembled an aircraft pair that had repeatedly come close to conflicting during training. This is likely because aircraft altitude (the feature manipulated between training and test) was attended to by participants when proactively controlling aircraft. In contrast, a minor change to the relative position of a repeated nonconflicting aircraft pair moderately impaired conflict detection (negative transfer). There was strong evidence for the null hypothesis that positive transfer was not impacted by dividing participant attention, which suggests that part of the information retrieved regarding prior aircraft events was perceptual (the new aircraft pair "looked" like a conflict based on familiarity). These findings extend the effects previously reported by Loft, Humphreys, and Neal (2004), answering the recent strong and unanimous calls across the psychological science discipline to formally establish the robustness and generality of previously published effects. (PsycINFO Database Record PMID:27295467

  20. Using memory for prior aircraft events to detect conflicts under conditions of proactive air traffic control and with concurrent task requirements.

    PubMed

    Bowden, Vanessa K; Loft, Shayne

    2016-06-01

    In 2 experiments we examined the impact of memory for prior events on conflict detection in simulated air traffic control under conditions where individuals proactively controlled aircraft and completed concurrent tasks. Individuals were faster to detect conflicts that had repeatedly been presented during training (positive transfer). Bayesian statistics indicated strong evidence for the null hypothesis that conflict detection was not impaired for events that resembled an aircraft pair that had repeatedly come close to conflicting during training. This is likely because aircraft altitude (the feature manipulated between training and test) was attended to by participants when proactively controlling aircraft. In contrast, a minor change to the relative position of a repeated nonconflicting aircraft pair moderately impaired conflict detection (negative transfer). There was strong evidence for the null hypothesis that positive transfer was not impacted by dividing participant attention, which suggests that part of the information retrieved regarding prior aircraft events was perceptual (the new aircraft pair "looked" like a conflict based on familiarity). These findings extend the effects previously reported by Loft, Humphreys, and Neal (2004), answering the recent strong and unanimous calls across the psychological science discipline to formally establish the robustness and generality of previously published effects. (PsycINFO Database Record

  1. Novel process of bio-chemical ammonia removal from air streams using a water reflux system and zeolite as filter media.

    PubMed

    Vitzthum von Eckstaedt, Sebastian; Charles, Wipa; Ho, Goen; Cord-Ruwisch, Ralf

    2016-02-01

    A novel biofilter that removes ammonia from air streams and converts it to nitrogen gas has been developed and operated continuously for 300 days. The ammonia from the incoming up-flow air stream is first absorbed into water and the carrier material, zeolite. A continuous gravity reflux of condensed water from the exit of the biofilter provides moisture for nitrifying bacteria to develop and convert dissolved ammonia (ammonium) to nitrite/nitrate. The down-flow of the condensed water reflux washes down nitrite/nitrate preventing ammonium and nitrite/nitrate accumulation at the top region of the biofilter. The evaporation caused by the inflow air leads to the accumulation of nitrite to extremely high concentrations in the bottom of the biofilter. The high nitrite concentrations favour the spontaneous chemical oxidation of ammonium by nitrite to nitrogen (N2). Tests showed that this chemical reaction was catalysed by the zeolite filter medium and allowed it to take place at room temperature. This study shows that ammonia can be removed from air streams and converted to N2 in a fully aerated single step biofilter. The process also overcomes the problem of microorganism-inhibition and resulted in zero leachate production. PMID:26363328

  2. Novel process of bio-chemical ammonia removal from air streams using a water reflux system and zeolite as filter media.

    PubMed

    Vitzthum von Eckstaedt, Sebastian; Charles, Wipa; Ho, Goen; Cord-Ruwisch, Ralf

    2016-02-01

    A novel biofilter that removes ammonia from air streams and converts it to nitrogen gas has been developed and operated continuously for 300 days. The ammonia from the incoming up-flow air stream is first absorbed into water and the carrier material, zeolite. A continuous gravity reflux of condensed water from the exit of the biofilter provides moisture for nitrifying bacteria to develop and convert dissolved ammonia (ammonium) to nitrite/nitrate. The down-flow of the condensed water reflux washes down nitrite/nitrate preventing ammonium and nitrite/nitrate accumulation at the top region of the biofilter. The evaporation caused by the inflow air leads to the accumulation of nitrite to extremely high concentrations in the bottom of the biofilter. The high nitrite concentrations favour the spontaneous chemical oxidation of ammonium by nitrite to nitrogen (N2). Tests showed that this chemical reaction was catalysed by the zeolite filter medium and allowed it to take place at room temperature. This study shows that ammonia can be removed from air streams and converted to N2 in a fully aerated single step biofilter. The process also overcomes the problem of microorganism-inhibition and resulted in zero leachate production.

  3. Energy Efficient Removal of Volatile Organic Compounds (VOCs) and Organic Hazardous Air Pollutants (o-HAPs) from Industrial Waste Streams by Direct Electron Oxidation

    SciTech Connect

    Testoni, A. L.

    2011-10-19

    This research program investigated and quantified the capability of direct electron beam destruction of volatile organic compounds and organic hazardous air pollutants in model industrial waste streams and calculated the energy savings that would be realized by the widespread adoption of the technology over traditional pollution control methods. Specifically, this research determined the quantity of electron beam dose required to remove 19 of the most important non-halogenated air pollutants from waste streams and constructed a technical and economic model for the implementation of the technology in key industries including petroleum refining, organic & solvent chemical production, food & beverage production, and forest & paper products manufacturing. Energy savings of 75 - 90% and green house gas reductions of 66 - 95% were calculated for the target market segments.

  4. Nutrient concentrations in a Pampasic first order stream with different land uses in the surrounding plots (Buenos Aires, Argentina).

    PubMed

    Mugni, Hernán; Paracampo, Ariel; Bonetto, Carlos

    2013-10-01

    The objective of this study was to assess the effect of land use on nutrient concentrations in a Pampasic stream. Soluble reactive phosphorus (SRP) concentrations in the stream were higher at a site surrounded by fertilized double-cropped wheat/soybeans than at unfertilized soybeans plots. Nitrate and SRP concentrations in the stream were lower at sites surrounded by soybeans than livestock. It is suggested that crop fertilization and cattle manure increased nutrients loads released to the stream. It is suggested that preservation and restoration of riparian habitats may benefit water quality by decreasing nutrient loads.

  5. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  6. Combined removal of BTEX in air stream by using mixture of sugar cane bagasse, compost and GAC as biofilter media.

    PubMed

    Mathur, Anil K; Majumder, C B; Chatterjee, Shamba

    2007-09-01

    Biofiltration of air stream containing mixture of benzene, toluene, ethyl benzene and o-xylene (BTEX) has been studied in a lab-scale biofilter packed with a mixture of compost, sugar cane bagasse and granulated activated carbon (GAC) in the ratio 55:30:15 by weight. Microbial acclimation was achieved in 30 days by exposing the system to average BTEX inlet concentration of 0.4194 gm(-3) at an empty bed residence time (EBRT) of 2.3 min. Biofilter achieved maximum removal efficiency more than 99% of all four compounds for throughout its operation at an EBRT of 2.3 min for an inlet concentration of 0.681 gm(-3), which is quite significance than the values reported in the literature. The results indicate that when the influent BTEX loadings were less than 68 gm(-3)h(-1) in the biofilter, nearly 100% removal could be achieved. A maximum elimination capacity (EC) of 83.65 gm(-3)h(-1) of the biofilter was obtained at inlet BTEX load of 126.5 gm(-3)h(-1) in phase IV. Elimination capacities of BTEX increased with the increase in influent VOC loading, but an opposite trend was observed for the removal efficiency. The production of CO(2) in each phase (gm(-3)h(-1)) was also observed at steady state (i.e. at maximum removal efficiency). Moreover, the high concentrations of nitrogen in the nutrient solution may adversely affect the microbial activity possibly due to the presence of high salt concentrations. Furthermore, an attempt was also made to isolate the most profusely grown BTEX-degrading strain. A Gram-positive strain had a high BTEX-degrading activity and was identified as Bacillus sphaericus by taxonomical analysis, biochemical tests and 16S rDNA gene analysis methods.

  7. Assessing Patterns in the Surface Electric Field Prior to First CG Flashes and After Last CG Flashes in Air-Mass Thunderstorms

    NASA Astrophysics Data System (ADS)

    Williams, D. E.; Beasley, W. H.; Hyland, P. T.

    2007-12-01

    In an effort to elicit patterns in the temporal and spatial evolution of the contours of surface electric field relevant to the occurrence of cloud-to-ground (CG) lightning, we have analyzed data from the network of 31 electric-field mills jointly operated by the John F. Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS). To identify cases of interest, we used lightning ground-strike data, maps of in-cloud lightning discharges, rainfall data, and radar data. In particular, we have focused on two critical problems: 1) estimation of when and where the first CG flash in a storm might occur and 2) assessment of the likelihood of CG flashes occurring late in a storm after a long period without a CG flash. Our long-term goal is to understand the evolution of surface contours of electric field for periods of 30 minutes or more before the first flash of any kind and 30 minutes or more before and after the last flash of any kind. For practical reasons, we are reporting here on analysis of data for periods of 30 minutes before the first CG flash and 30 minutes after the last CG flash in each storm of interest. We have analyzed electric-field data from isolated air-mass convective storms that developed over KSC/CCAFS from late May through early September, 2004-2006. To identify thunderstorms that fit the air-mass, or "pop-up" criteria, we started by examining rainfall and CG lightning data, then looked at radar data. Then, for the storms selected, we performed a two-pass Barnes objective analysis on the electric-field data. Each analysis cycle resulted in one contour plot of 20-second averaged data, yielding 90 plots for each 30 minute interval, which we then animated. This resulted in 58 animations of the field contours prior to first CG flashes and 62 animations of the field contours after last CG flashes. Preliminary impressions from examinations of these cases suggest that the electric-field contours before the first flash exhibit a smooth transition

  8. Insecticide toxicity to Hyalella curvispina in runoff and stream water within a soybean farm (Buenos Aires, Argentina).

    PubMed

    Mugni, H; Ronco, A; Bonetto, C

    2011-03-01

    Toxicity to the locally dominant amphipod Hyalella curvispina was assessed in a first-order stream running through a cultivated farm. Cypermethrin, chlorpyrifos, endosulfan and glyphosate were sprayed throughout the studied period. Toxicity was assayed under controlled laboratory conditions with runoff and stream water samples taken from the field under steady state and flood conditions. Ephemeral toxicity pulses were observed as a consequence of farm pesticide applications. After pesticide application, runoff water showed 100% mortality to H. curvispina for 1 month, but no mortality thereafter. Toxicity persistence was shortest in stream water, intermediate in stream sediments and longest in soil samples. Runoff had a more important toxicity effect than the exposure to direct aerial fumigation. The regional environmental features determining fast toxicity dissipation are discussed.

  9. Impact of a hydrophobic granular stream in water

    NASA Astrophysics Data System (ADS)

    Utter, Brian; Mandeles, Harry; Parkhouse, Jacob

    We experimentally investigate the flow of a stream of hydrophobic granular particles impacting a water surface from above. The granular sample is composed of a mixture of hydrophobic and hydrophilic grains and the concentration, stream diameter, and drop height are independently controlled. While granular flows are common in nature and industry, effects of surface chemistry on flow behavior have received relatively little attention. The present experiment complements rheological measurements performed in parallel and aims to elucidate prior experiments on hydrophobic samples in a rotating drum. The present experimental geometry allows us to compare the behavior of granular streams to prior work on impacts of solids and fluid streams. Sequential images of the granular stream in water are taken and analyzed. We present data on the size, length, and shape of the aggregate streams with variations in concentration, entering stream diameter, and drop height. We find that increased hydrophobic grain concentration leads to increased aggregation due to an effectively cohesive interaction mediated by entrained air. At lower concentrations, the stream exhibits a lateral instability. Finally, we will make connections to rheology and rotating drum results. This work was supported by NSF CBET award 1067598.

  10. Headaches prior to earthquakes

    NASA Astrophysics Data System (ADS)

    Morton, L. L.

    1988-06-01

    In two surveys of headaches it was noted that their incidence had increased significantly within 48 h prior to earthquakes from an incidence of 17% to 58% in the first survey using correlated samples and from 20.4% to 44% in the second survey using independent samples. It is suggested that an increase in positive air ions from rock compression may trigger head pain via a decrease in brain levels of the neurotransmitter serotonin. The findings are presented as preliminary, with the hope of generating further research efforts in areas more prone to earthquakes.

  11. FIELD METHODS TO MEASURE CONTAMINANT REMOVAL EFFECTIVENESS OF GAS-PHASE AIR FILTRATION EQUIPMENT - PHASE 1: SEARCH OF LITERATURE AND PRIOR ART

    EPA Science Inventory

    The report, Phase 1 of a two-phase research project, gives results of a literature search into the
    effectiveness of in-field gas-phase air filtration equipment (GPAFE) test methods, including required instrumentation and costs. GPAFE has been used in heating, ventilation, and ...

  12. Winter stream temperature in the rain-on-snow zone

    NASA Astrophysics Data System (ADS)

    Leach, J. A.; Moore, R. D.

    2012-12-01

    Stream temperature is a principal determinant of aquatic ecosystem composition and productivity. There are increasing concerns that changes in land cover and climatic conditions could produce changes in stream thermal regimes that would be deleterious to existing aquatic communities. Most stream temperature research has focused on summer periods and few studies have examined winter periods despite the growing recognition of its biological importance. The winter thermal regimes of Pacific Northwest headwater streams, which provide vital winter habitat for salmonids and their food sources, may be particularly sensitive to changes in climate because they can remain ice-free throughout the year and are often located in rain-on-snow zones. This study examined winter stream temperature patterns and controls in small headwater catchments within the rain-on-snow zone at the Malcolm Knapp Research Forest, near Vancouver, British Columbia, Canada. Two working hypotheses were addressed by this study: (1) winter stream temperatures are primarily controlled by advective fluxes associated with runoff processes and (2) stream temperatures should be depressed during rain-on-snow events, compared to rain on bare ground, due to the cooling effect of rain passing through the snowpack prior to infiltrating the soil or being delivered to the stream as saturation-excess overland flow. These hypotheses were tested statistically using historical stream temperature data and modelled snowpack dynamics for a forested headwater catchment. When snow was not present, daily stream temperature during winter rain events tended to increase with increasing air temperature. However, when snow was present, stream temperature was capped at about 5 °C, regardless of air temperature. This historical analysis was complemented with detailed field data collected during the winter of 2011-2012 from an ongoing field study in a partially logged catchment. Stream temperature response to a large rain

  13. Experimental treatment of a refinery waste air stream, for BTEX removal, by water scrubbing and biotrickling on a bed of Mitilus edulis shells.

    PubMed

    Torretta, Vincenzo; Collivignarelli, Maria Cristina; Raboni, Massimo; Viotti, Paolo

    2015-01-01

    The paper presents the results of a two-stage pilot plant for the removal of benzene, toluene, ethylbenzene and xylene (BTEX) from a waste air stream of a refinery wastewater treatment plant (WWTP). The pilot plant consisted of a water scrubber followed by a biotrickling filter (BTF). The exhausted air was drawn from the main works of the WWTP in order to prevent the free migration to the atmosphere of these volatile hazardous contaminants. Concentrations were detected at average values of 12.4 mg Nm(-3) for benzene, 11.1 mg Nm(-3) for toluene, 2.7 mg Nm(-3) for ethylbenzene and 9.5 mg Nm(-3) for xylene, with considerable fluctuation mainly for benzene and toluene (peak concentrations of 56.8 and 55.0 mg Nm(-3), respectively). The two treatment stages proved to play an effective complementary task: the water scrubber demonstrated the ability to remove the concentration peaks, whereas the BTF was effective as a polishing stage. The overall average removal efficiency achieved was 94.8% while the scrubber and BTF elimination capacity were 37.8 and 15.6 g BTEX d(-1) m(-3), respectively. This result has led to outlet average concentrations of 1.02, 0.25, 0.32 and 0.26 mg Nm(-3) for benzene, toluene, ethylbenzene and xylene, respectively. The paper also compares these final concentrations with toxic and odour threshold concentrations.

  14. Atmospheric structure prior to tornadoes as derived from proximity and precedent upper-air soundings, covering the period April 1977-June 1979

    SciTech Connect

    Taylor, G.E.; Darkow, G.L.

    1982-05-01

    The uniqueness of the thermodynamic and dynamic structure of the atmosphere in the area of imminent tornado bearing storm development is analyzed by comparing 115 tornado proximity soundings with upper air soundings made at the same location 6 and 12 hours earlier (precedent soundings) and with soundings made simultaneously at neighboring upper air stations. The comparisons suggest that both the proximity station and the neighboring station upstream with respect to the mean flow in the low level moist air display very similar degrees of hydrostatic and potential-convective instability by late afternoon. The principal difference is in the wind profiles at the two locations. The tornado proximity station displays significantly stronger wind speeds above 1 km with the most striking difference being in the vertical shear of the wind in the layer from 1 to 3 km above ground level. In this layer the winds at the proximity station show an average increase of about 3 m sec/sup -1/ while the upstream, non-tornadic, station shows a slight decrease of wind speed with height.

  15. Toluene removal from waste air stream by the catalytic ozonation process with MgO/GAC composite as catalyst.

    PubMed

    Rezaei, Fatemeh; Moussavi, Gholamreza; Bakhtiari, Alireza Riyahi; Yamini, Yadollah

    2016-04-01

    This paper investigates the catalytic potential of MgO/GAC composite for toluene elimination from waste air in the catalytic ozonation process (COP). The MgO/GAC composite was a micro-porous material with the BET surface area of 1082m(2)/g. Different functional groups including aromatic CC, saturated CO of anhydrates, hydroxyl groups and SH bond of thiols were identified on the surface of MgO/GAC. Effects of residence time (0.5-4s), inlet toluene concentration (100-400ppmv) and bed temperature (25-100°C) were investigated on degradation of toluene in COP. Impregnation of GAC with MgO increased the breakthrough time and removal capacity by 73.9% and 64.6%, respectively, at the optimal conditions. The catalytic potential of the GAC and MgO/GAC for toluene degradation was 11.1% and 90.6%, respectively, at the optimum condition. The highest removal capacity using MgO/GAC (297.9gtoulene/gMgO/GAC) was attained at 100°C, whereas the highest removal capacity of GAC (128.5mgtoulene/gGAC) was obtained at 25°C. Major by-products of the toluene removal in COP with GAC were Formic acid, benzaldehyde, O-nitro-p-cresol and methyl di-phenyl-methane. MgO/GAC could greatly catalyze the decomposition of toluene in COPand formic acid was the main compound desorbed from the catalyst. Accordingly, the MgO/GAC is an efficient material to catalyze the ozonation of hydrocarbon vapors. PMID:26784452

  16. Fighting Prior Review.

    ERIC Educational Resources Information Center

    Bowen, John

    1990-01-01

    Reviews arguments for and against prior administrative review and censorship of student expression. Suggests that prior review strips any pretense of democracy from many American educational institutions. Argues that prior review is journalistically inappropriate, educationally unsound, and practically illogical. (KEH)

  17. Nitrate deposition and impact on Adirondack streams

    SciTech Connect

    Simonin, H.A.; Kretser, W.A.

    1997-12-31

    Acidic deposition has a great impact on water chemistry and fish populations in the Adirondack region. Although the Clean Air Act Amendments of 1990 have resulted in some reductions of sulfate deposition, nitrate deposition has not yet been well controlled, and continues to impact aquatic resources. As part of the USEPA funded Episodic Response Project four Adirondack headwater streams were intensively monitored over an 18 month period. Atmospheric deposition was also monitored at a centrally located station. The quantity of nitrate being deposited on the study watersheds was calculated based on monthly net deposition data which ranged from 0.6 kg/ha/month to 3.6 kg/ha/month. These data were then compared to the monthly export of nitrate from the watershed in these streams. Nitrate concentrations were highest in the streamwater during the spring snowmelt period prior to the time when forest vegetation actively utilizes nitrate. On an annual basis the amount of nitrate which left the watershed via stream water exceeded the amount which fell as nitrate deposition. These data are important in documenting the impact of nitrate in the acidification of Adirondack streams during the spring, which coincides with brook trout hatching. Control programs for nitrous oxide emissions are presently aimed at reducing ozone levels during the May-September period. These emissions control programs need to be expanded to also reduce nitrate deposition in the sensitive Adirondack region during the winter and spring periods when nitrate deposition has its greatest impact on aquatic resources.

  18. Injection, atomization, ignition and combustion of liquid fuels in high-speed air streams. Annual scientific report 1 December 81-31 December 82

    SciTech Connect

    Schetz, J.A.

    1983-01-01

    A simulation approach to studying hot flow subsonic cross-stream fuel injection problems in a less complex and costly cold flow facility was developed. A typical ramjet combustion chamber fuel injection problem was posed where ambient temperature fuel (Kerosene) is injected into a hot airstream. This case was transformed through two new similarity parameters involving injection and freestream properties to a simulated case where a chilled injectant is injected into an ambient temperature airstream. Experiments for the simulated case using chilled Freon-12 injected into the Va. Tech 23 x 23 cm. blow-down wind tunnel at a freestream Mach number of 0.44 were run. The freestream stagnation pressure and temperature were held at 2.5 atm. and 300 degrees K respectively. Results showed a clear picture of the mechanisms of jet decomposition in the presence of rapid vaporization. Immediately after injection a vapor cloud was formed in the jet plume, which dissipated downstream leaving droplets on the order of 8 to 10 microns in diameter for the conditions examined. This represents a substantial reduction compared to baseline tests run at the same conditions with water which had little vaporization. The desirability of using slurry fuels for aerospace application has long been recognized, but the problems of slurry combustion have delayed their use. The present work is an experimental and numerical investigation into the break-up and droplet formation of laminar slurry jets issuing into quiescent air.

  19. Ammonia removal from air stream and biogas by a H2SO4 impregnated adsorbent originating from waste wood-shavings and biosolids.

    PubMed

    Guo, Xuejun Jack; Tak, Jin Kwon; Johnson, Richard L

    2009-07-15

    A new and cost-effective adsorbent N-TRAP, made from waste wood-shavings and anaerobically digestion biosolids and impregnated with H(2)SO(4), was applied for the ammonia removal from air stream and biogas with high efficiency and effectiveness. Bearing a 75-80 and 65 wt.% sulfuric acid, the N-TRAPs mediated with wood shavings and biosolids showed the maximum ammonia adsorption capacity of 260-280 and 230 mg g(-1), respectively. Gas temperatures (20 and 60 degrees C) and moisture content (100% relative humidity) had no significantly negative effect on ammonia capture performance when temperature in the fixed-bed column was kept equalled to or slightly above the feed gas temperature. The pressure drop increased significantly when NH(3) began to break through the N-TRAP stripper due to the formation of ammonium sulfate blocking the vacuum space of packed adsorbent. At last, an alternative N-TRAP filter bed design was proposed to resolve the problem of pressure drop evolution.

  20. Methods of separating particulate residue streams

    DOEpatents

    Hoskinson, Reed L.; Kenney, Kevin L.; Wright, Christopher T.; Hess, J. Richard

    2011-04-05

    A particulate residue separator and a method for separating a particulate residue stream may include an air plenum borne by a harvesting device, and have a first, intake end and a second, exhaust end; first and second particulate residue air streams that are formed by the harvesting device and that travel, at least in part, along the air plenum and in a direction of the second, exhaust end; and a baffle assembly that is located in partially occluding relation relative to the air plenum and that substantially separates the first and second particulate residue air streams.

  1. Statistical Modeling of Daily Stream Temperature for Mitigating Fish Mortality

    NASA Astrophysics Data System (ADS)

    Caldwell, R. J.; Rajagopalan, B.

    2011-12-01

    Water allocations in the Central Valley Project (CVP) of California require the consideration of short- and long-term needs of many socioeconomic factors including, but not limited to, agriculture, urban use, flood mitigation/control, and environmental concerns. The Endangered Species Act (ESA) ensures that the decision-making process provides sufficient water to limit the impact on protected species, such as salmon, in the Sacramento River Valley. Current decision support tools in the CVP were deemed inadequate by the National Marine Fisheries Service due to the limited temporal resolution of forecasts for monthly stream temperature and fish mortality. Finer scale temporal resolution is necessary to account for the stream temperature variations critical to salmon survival and reproduction. In addition, complementary, long-range tools are needed for monthly and seasonal management of water resources. We will present a Generalized Linear Model (GLM) framework of maximum daily stream temperatures and related attributes, such as: daily stream temperature range, exceedance/non-exceedance of critical threshold temperatures, and the number of hours of exceedance. A suite of predictors that impact stream temperatures are included in the models, including current and prior day values of streamflow, water temperatures of upstream releases from Shasta Dam, air temperature, and precipitation. Monthly models are developed for each stream temperature attribute at the Balls Ferry gauge, an EPA compliance point for meeting temperature criteria. The statistical framework is also coupled with seasonal climate forecasts using a stochastic weather generator to provide ensembles of stream temperature scenarios that can be used for seasonal scale water allocation planning and decisions. Short-term weather forecasts can also be used in the framework to provide near-term scenarios useful for making water release decisions on a daily basis. The framework can be easily translated to other

  2. Stream Processors

    NASA Astrophysics Data System (ADS)

    Erez, Mattan; Dally, William J.

    Stream processors, like other multi core architectures partition their functional units and storage into multiple processing elements. In contrast to typical architectures, which contain symmetric general-purpose cores and a cache hierarchy, stream processors have a significantly leaner design. Stream processors are specifically designed for the stream execution model, in which applications have large amounts of explicit parallel computation, structured and predictable control, and memory accesses that can be performed at a coarse granularity. Applications in the streaming model are expressed in a gather-compute-scatter form, yielding programs with explicit control over transferring data to and from on-chip memory. Relying on these characteristics, which are common to many media processing and scientific computing applications, stream architectures redefine the boundary between software and hardware responsibilities with software bearing much of the complexity required to manage concurrency, locality, and latency tolerance. Thus, stream processors have minimal control consisting of fetching medium- and coarse-grained instructions and executing them directly on the many ALUs. Moreover, the on-chip storage hierarchy of stream processors is under explicit software control, as is all communication, eliminating the need for complex reactive hardware mechanisms.

  3. Dynamical modelling of meteoroid streams

    NASA Astrophysics Data System (ADS)

    Clark, D. L.; Wiegert, P. A.

    2014-07-01

    Accurate simulations of meteoroid streams permit the prediction of stream interaction with Earth, and provide a measure of risk to Earth satellites and interplanetary spacecraft. Current cometary ejecta and meteoroid stream models have been somewhat successful in predicting some stream observations, but have required significant assumptions and simplifications. Extending on the approach of Vaubaillon et al. 2005, we model dust ejection from the cometary nucleus, and generate sample particles representing bins of distinct dynamical evolution-regulating characteristics (size, density, direction, albedo). Ephemerides of the sample particles are integrated and recorded for later assignment of weights based on model parameter changes. To assist in model analysis we are developing interactive software to permit the "turning of knobs" of model parameters, allowing for near-real-time 3D visualization of resulting stream structure. Using the tool, we will revisit prior assumptions made, and will observe the impact of introducing non-uniform and time-variant cometary surface attributes and processes.

  4. Winter stream temperature in the rain-on-snow zone of the Pacific northwest: influences of hillslope runoff and transient snow cover

    NASA Astrophysics Data System (ADS)

    Leach, J. A.; Moore, R. D.

    2013-10-01

    Stream temperature dynamics during winter are less well studied than summer thermal regimes, but the winter season thermal regime can be critical for fish growth and development in coastal catchments. The winter thermal regimes of Pacific Northwest headwater streams, which provide vital winter habitat for salmonids and their food sources, may be particularly sensitive to changes in climate because they can remain ice-free throughout the year and are often located in rain-on-snow zones. This study examined winter stream temperature patterns and controls in small headwater catchments within the rain-on-snow zone at the Malcolm Knapp Research Forest, near Vancouver, British Columbia, Canada. Two hypotheses were addressed by this study: (1) winter stream temperatures are primarily controlled by advective fluxes associated with runoff processes and (2) stream temperatures should be depressed during rain-on-snow events, compared to rain-on-bare-ground, due to the cooling effect of rain passing through the snowpack prior to infiltrating the soil or being delivered to the stream as saturation-excess overland flow. A reach-scale energy budget analysis of two winter seasons revealed that the advective energy input associated with hillslope runoff overwhelms the effects of energy exchanges at the stream surface during rain and rain-on-snow events. Historical stream temperature data and modelled snowpack dynamics were used to explore the influence of transient snow cover on stream temperature over 13 winters. When snow was not present, daily stream temperature during winter rain events tended to increase with increasing air temperature. However, when snow was present, stream temperature was capped at about 5 °C, regardless of air temperature. The stream energy budget modelling and historical analysis support both of our hypotheses. A key implication is that climatic warming may generate higher winter stream temperatures in the rain-on-snow zone due to both increased rain

  5. Constructing priors in synesthesia.

    PubMed

    van Leeuwen, Tessa M

    2014-01-01

    A new theoretical framework (PPSMC) applicable to synesthesia has been proposed, in which the discrepancy between the perceptual reality of (some) synesthetic concurrents and their subjective non-veridicality is being explained. The PPSMC framework stresses the relevance of the phenomenology of synesthesia for synesthesia research-and beyond. When describing the emergence and persistence of synesthetic concurrents under PPSMC, it is proposed that precise, high-confidence priors are crucial in synesthesia. I discuss the construction of priors in synesthesia.

  6. Stream Studies.

    ERIC Educational Resources Information Center

    Hamilton City Board of Education (Ontario).

    This manual provides teachers with some knowledge of ecological study methods and techniques used in collecting data when plants and animals are studied in the field. Most activities deal with the interrelatedness of plant and animal life to the structure and characteristics of a stream and pond. Also included in this unit plan designed for the…

  7. Stream Studies.

    ERIC Educational Resources Information Center

    Stein, Scott

    1997-01-01

    Outlines a science curriculum reform effort aimed at enabling students to collect original data concerning an environmental parameter such as water quality on a yearly basis. Students track the overall health of the stream by analyzing both biotic and abiotic factors. (DDR)

  8. Describing Story Evolution from Dynamic Information Streams

    SciTech Connect

    Rose, Stuart J.; Butner, R. Scott; Cowley, Wendy E.; Gregory, Michelle L.; Walker, Julia

    2009-10-12

    Sources of streaming information, such as news syndicates, publish information continuously. Information portals and news aggregators list the latest information from around the world enabling information consumers to easily identify events in the past 24 hours. The volume and velocity of these streams causes information from prior days’ to quickly vanish despite its utility in providing an informative context for interpreting new information. Few capabilities exist to support an individual attempting to identify or understand trends and changes from streaming information over time. The burden of retaining prior information and integrating with the new is left to the skills, determination, and discipline of each individual. In this paper we present a visual analytics system for linking essential content from information streams over time into dynamic stories that develop and change over multiple days. We describe particular challenges to the analysis of streaming information and explore visual representations for showing story change and evolution over time.

  9. Differential Temperature Sensitivity of Mountain Streams: Cool Streams Keep Their Cool

    NASA Astrophysics Data System (ADS)

    Luce, C.; Staab, B. P.; Kramer, M. G.; Wenger, S. J.; Isaak, D.; McConnell, C.

    2015-12-01

    Estimating differences in thermal response among streams to a warming climate is important for prioritizing native fish conservation efforts. While there are many estimates of air temperature responses to climate change, the sensitivity of streams, particularly small headwater streams, to warming temperatures is less well understood. A substantial body of literature correlates sub-annual scale temperature variations in air and stream temperatures driven by annual cycles in solar angle. However, these may be a low-precision proxy for climate change driven changes in the stream energy balance, particularly in warmer months. We analyzed summer stream temperature records from forested streams in the Pacific Northwest for interannual correlations to air temperature and standardized annual streamflow departures. A significant pattern emerged where cold streams always showed lower sensitivities to air temperature variation, while warm streams could be insensitive or sensitive depending on geological or vegetation context. A pattern where cold streams are less sensitive to direct temperature increases is important for conservation planning, although substantial questions yet remain for secondary effects related to changes in snowpack, summer runoff, groundwater, or vegetation.

  10. Internal-liquid-film-cooling Experiments with Air-stream Temperatures to 2000 Degrees F. in 2- and 4-inch-diameter Horizontal Tubes

    NASA Technical Reports Server (NTRS)

    Kinney, George R; Abramson, Andrew E; Sloop, John L

    1952-01-01

    Report presents the results of an investigation conducted to determine the effectiveness of liquid-cooling films on the inner surfaces of tubes containing flowing hot air. Experiments were made in 2- and 4-inch-diameter straight metal tubes with air flows at temperatures from 600 degrees to 2000 degrees F. and diameter Reynolds numbers from 2.2 to 14 x 10(5). The film coolant, water, was injected around the circumference at a single axial position on the tubes at flow rates from 0.02 to .24 pound per second per foot of tube circumference (0.8 to 12 percent of the air flow). Liquid-coolant films were established and maintained around and along the tube wall in concurrent flow with the hot air. The results indicated that, in order to film cool a given surface area with as little coolant flow as possible, it may be necessary to limit the flow of coolant introduced at a single axial position and to introduce it at several axial positions. The flow rate of inert coolant required to maintain liquid-film cooling over a given area of tube surface can be estimated when the gas-flow conditions are known by means of a generalized plot of the film-cooling data.

  11. The effect of Gulf Stream-induced baroclinicity on US East Coast winter cyclones

    SciTech Connect

    Cione, J.J.; Raman, S.; Pietrafesa, L.J. )

    1993-02-01

    Midlatitude cyclones develop off the Carolinas during winters and move north producing gale-force winds, ice, and heavy snow. It is believed that boundary-layer and air-sea interaction processes are very important during the development stages of these East Coast storms. The marine boundary layer (MBL) off the mid-Atlantic coastline is highly baroclinic due to the proximity of the Gulf Stream just offshore. Typical horizontal distances between the Wilmington coastline and the western edge of the Gulf Stream vary between 90 and 250 km annually, and this distance can deviate by over 30 km within a single week. While similar weekly Gulf Stream position standard deviations also exist at Cape Hatteras, the average annual distance to the Gulf Stream frontal zone is much smaller off Cape Hatteras, normally ranging between 30 and 100 km. This research investigates the low-level baroclinic conditions present prior to observed storm events. The examination of nine years of data on the Gulf Stream position and East Coast winter storms seems to indicate that the degree of low-level baroclinicity and modification existing prior to a cyclonic event may significantly affect the rate of cyclonic deepening off the mid-Atlantic coastline. Statistical analyses linking the observed surface-pressure decrease with both the Gulf Stream frontal location and the prestorm coastal baroclinic conditions are presented. These results quantitatively indicate that Gulf Stream-induced wintertime baroclinicity may significantly affect the regional intensification of East Coast winter cyclones. 20 refs., 9 figs., 1 tab.

  12. Emergence and fate of cyclic volatile polydimethylsiloxanes (D4, D5) in municipal waste streams: release mechanisms, partitioning and persistence in air, water, soil and sediments.

    PubMed

    Surita, Sharon C; Tansel, Berrin

    2014-01-15

    Siloxane use in consumer products (i.e., fabrics, paper, concrete, wood, adhesive surfaces) has significantly increased in recent years due to their excellent water repelling and antimicrobial characteristics. The objectives of this study were to evaluate the release mechanisms of two siloxane compounds, octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5), which have been detected both at landfills and wastewater treatment plants, estimate persistence times in different media, and project release quantities over time in relation to their increasing use. Analyses were conducted based on fate and transport mechanisms after siloxanes enter waste streams. Due to their high volatility, the majority of D4 and D5 end up in the biogas during decomposition. D5 is about ten times more likely to partition into the solid phase (i.e., soil, biosolids). D5 concentrations in the wastewater influent and biogas are about 16 times and 18 times higher respectively, in comparison to the detected levels of D4.

  13. Emergence and fate of cyclic volatile polydimethylsiloxanes (D4, D5) in municipal waste streams: release mechanisms, partitioning and persistence in air, water, soil and sediments.

    PubMed

    Surita, Sharon C; Tansel, Berrin

    2014-01-15

    Siloxane use in consumer products (i.e., fabrics, paper, concrete, wood, adhesive surfaces) has significantly increased in recent years due to their excellent water repelling and antimicrobial characteristics. The objectives of this study were to evaluate the release mechanisms of two siloxane compounds, octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5), which have been detected both at landfills and wastewater treatment plants, estimate persistence times in different media, and project release quantities over time in relation to their increasing use. Analyses were conducted based on fate and transport mechanisms after siloxanes enter waste streams. Due to their high volatility, the majority of D4 and D5 end up in the biogas during decomposition. D5 is about ten times more likely to partition into the solid phase (i.e., soil, biosolids). D5 concentrations in the wastewater influent and biogas are about 16 times and 18 times higher respectively, in comparison to the detected levels of D4. PMID:24012894

  14. Accounting for groundwater in stream fish thermal habitat responses to climate change

    USGS Publications Warehouse

    Snyder, Craig D.; Hitt, Nathaniel P.; Young, John A.

    2015-01-01

    Forecasting climate change effects on aquatic fauna and their habitat requires an understanding of how water temperature responds to changing air temperature (i.e., thermal sensitivity). Previous efforts to forecast climate effects on brook trout habitat have generally assumed uniform air-water temperature relationships over large areas that cannot account for groundwater inputs and other processes that operate at finer spatial scales. We developed regression models that accounted for groundwater influences on thermal sensitivity from measured air-water temperature relationships within forested watersheds in eastern North America (Shenandoah National Park, USA, 78 sites in 9 watersheds). We used these reach-scale models to forecast climate change effects on stream temperature and brook trout thermal habitat, and compared our results to previous forecasts based upon large-scale models. Observed stream temperatures were generally less sensitive to air temperature than previously assumed, and we attribute this to the moderating effect of shallow groundwater inputs. Predicted groundwater temperatures from air-water regression models corresponded well to observed groundwater temperatures elsewhere in the study area. Predictions of brook trout future habitat loss derived from our fine-grained models were far less pessimistic than those from prior models developed at coarser spatial resolutions. However, our models also revealed spatial variation in thermal sensitivity within and among catchments resulting in a patchy distribution of thermally suitable habitat. Habitat fragmentation due to thermal barriers therefore may have an increasingly important role for trout population viability in headwater streams. Our results demonstrate that simple adjustments to air-water temperature regression models can provide a powerful and cost-effective approach for predicting future stream temperatures while accounting for effects of groundwater.

  15. Accounting for groundwater in stream fish thermal habitat responses to climate change.

    PubMed

    Snyder, Craig D; Hitt, Nathaniel P; Young, John A

    2015-07-01

    Forecasting climate change effects on aquatic fauna and their habitat requires an understanding of how water temperature responds to changing air temperature (i.e., thermal sensitivity). Previous efforts to forecast climate effects on brook trout (Salvelinus fontinalis) habitat have generally assumed uniform air-water temperature relationships over large areas that cannot account for groundwater inputs and other processes that operate at finer spatial scales. We developed regression models that accounted for groundwater influences on thermal sensitivity from measured air-water temperature relationships within forested watersheds in eastern North America (Shenandoah National Park, Virginia, USA, 78 sites in nine watersheds). We used these reach-scale models to forecast climate change effects on stream temperature and brook trout thermal habitat, and compared our results to previous forecasts based upon large-scale models. Observed stream temperatures were generally less sensitive to air temperature than previously assumed, and we attribute this to the moderating effect of shallow groundwater inputs. Predicted groundwater temperatures from air-water regression models corresponded well to observed groundwater temperatures elsewhere in the study area. Predictions of brook trout future habitat loss derived from our fine-grained models. were far less pessimistic than those from prior models developed at coarser spatial resolutions. However, our models also revealed spatial variation in thermal sensitivity within and among catchments resulting in a patchy distribution of thermally suitable habitat. Habitat fragmentation due to thermal barriers therefore may have an increasingly important role for trout population viability in headwater streams. Our results demonstrate that simple adjustments to air-water temperature regression models can provide a powerful and cost-effective approach for predicting future stream temperatures while accounting for effects of groundwater.

  16. Accounting for groundwater in stream fish thermal habitat responses to climate change.

    PubMed

    Snyder, Craig D; Hitt, Nathaniel P; Young, John A

    2015-07-01

    Forecasting climate change effects on aquatic fauna and their habitat requires an understanding of how water temperature responds to changing air temperature (i.e., thermal sensitivity). Previous efforts to forecast climate effects on brook trout (Salvelinus fontinalis) habitat have generally assumed uniform air-water temperature relationships over large areas that cannot account for groundwater inputs and other processes that operate at finer spatial scales. We developed regression models that accounted for groundwater influences on thermal sensitivity from measured air-water temperature relationships within forested watersheds in eastern North America (Shenandoah National Park, Virginia, USA, 78 sites in nine watersheds). We used these reach-scale models to forecast climate change effects on stream temperature and brook trout thermal habitat, and compared our results to previous forecasts based upon large-scale models. Observed stream temperatures were generally less sensitive to air temperature than previously assumed, and we attribute this to the moderating effect of shallow groundwater inputs. Predicted groundwater temperatures from air-water regression models corresponded well to observed groundwater temperatures elsewhere in the study area. Predictions of brook trout future habitat loss derived from our fine-grained models. were far less pessimistic than those from prior models developed at coarser spatial resolutions. However, our models also revealed spatial variation in thermal sensitivity within and among catchments resulting in a patchy distribution of thermally suitable habitat. Habitat fragmentation due to thermal barriers therefore may have an increasingly important role for trout population viability in headwater streams. Our results demonstrate that simple adjustments to air-water temperature regression models can provide a powerful and cost-effective approach for predicting future stream temperatures while accounting for effects of groundwater

  17. Remote Sensing of Atmospheric and Ionospheric Signals Prior to the Mw 8.3 Illapel Earthquake, Chile 2015

    NASA Astrophysics Data System (ADS)

    Mansouri Daneshvar, Mohammad Reza; Freund, Friedemann T.

    2016-08-01

    In the present study, a number of atmospheric and some ionospheric anomalies are analyzed, which were recorded prior to the Mw 8.3 Illapel earthquake of September 16, 2015. This very large earthquake occurred in Central Chile, close to the coast, as the result of thrust faulting on the interface between the Nazca Plate and South American continent. Using remotely sensed data extracted from NASA/Giovanni, NOAA/NCEP, and NOAA/NGDC, atmospheric and ionospheric anomalies were observed that co-registered 35-40 and 25-30 days prior to the main shock, respectively. With reference to long-term time series over the epicentral area, significant atmospheric anomalies were recorded for cloud cover, geopotential height, precipitation rates, surface air pressure, omega, stream function, and wind vectors—all in the time window of August 5-10, 2015, 35-40 days prior to the main shock. Anomalous TEC maps were recorded for the same time period. Satellite images indicate the formation of an unusual cyclone, presumably triggered by air turbulences and abnormal atmospheric conditions over the epicentral area, including strong vertical winds. Data from the Jicamarca radio observatory in Peru, more than 2000 km to the North, reveal anomalous ionospheric variations on August 15-20, 2015 with respect to international reference ionosphere thickness parameters and the altitude of the F layer. The observed anomalies are consistent with processes that occur at the ground-to-air interface due to the stress activation of peroxy defects in the hypocentral volume. The flow of positive hole charge carriers to the Earth surface expected to have led to massive air ionization, generating at first primarily positive airborne ions, then negative air ions plus ozone. Understanding the sequence of processes inside the Earth's crust and at the ground-to-air interface provides information not previously available about the causal and temporal linkages between the various pre-earthquake phenomena and the

  18. Reconstructing the atmospheric concentration and emissions of CF4, C2F6 and C3F8 prior to direct atmospheric measurements, using air from polar firn and ice

    NASA Astrophysics Data System (ADS)

    Trudinger, Cathy; Etheridge, David; Sturges, William; Vollmer, Martin; Miller, Benjamin; Worton, David; Rigby, Matt; Krummel, Paul; Martinerie, Patricia; Witrant, Emmanuel; Rayner, Peter; Battle, Mark; Blunier, Thomas; Fraser, Paul; Laube, Johannes; Mani, Frances; Mühle, Jens; O'Doherty, Simon; Schwander, Jakob; Steele, Paul

    2015-04-01

    Perfluorocarbons are very potent and long-lived greenhouse gases in the atmosphere, released predominantly during aluminium production, electronic chip manufacture and refrigeration. Mühle et al. (2010) presented records of the concentration and inferred emissions of CF4 (PFC-14), C2F6 (PFC-116) and C3F8 (PFC-218) from the 1970s up to 2008, using measurements from the Cape Grim Air Archive and a suite of tanks with old Northern Hemisphere air, and the AGAGE in situ network. Mühle et al. (2010) also estimated pre-industrial concentrations of these compounds from a small number of polar firn and ice core samples. Here we present measurements of air from polar firn at four sites (DSSW20K, EDML, NEEM and South Pole) and from air bubbles trapped in ice at two sites (DE08 and DE08-2), along with recent atmospheric measurements to give a continuous record of concentration from preindustrial levels up to the present. We estimate global emissions (with uncertainties) consistent with the concentration records. The uncertainty analysis takes into account uncertainties in characterisation of the age of air in firn and ice by the use of two different (independently-calibrated) firn models (the CSIRO and LGGE-GIPSA firn models). References Mühle, J., A.L. Ganesan, B.R. Miller, P.K. Salameh, C.M. Harth, B.R. Greally, M. Rigby, L.W. Porter, L. P. Steele, C.M. Trudinger, P.B. Krummel, S. O'Doherty, P.J. Fraser, P.G. Simmonds, R.G. Prinn, and R.F. Weiss, Perfluorocarbons in the global atmosphere: tetrafluoromethane, hexafluoroethane, and octafluoropropane, Atmos. Chem. Phys., 10, 5145-5164, doi:10.5194/acp-10-5145-2010, 2010.

  19. Unconsciously elicited perceptual prior

    PubMed Central

    Chang, Raymond; Baria, Alexis T.; Flounders, Matthew W.; He, Biyu J.

    2016-01-01

    Increasing evidence over the past decade suggests that vision is not simply a passive, feed-forward process in which cortical areas relay progressively more abstract information to those higher up in the visual hierarchy, but rather an inferential process with top-down processes actively guiding and shaping perception. However, one major question that persists is whether such processes can be influenced by unconsciously perceived stimuli. Recent psychophysics and neuroimaging studies have revealed that while consciously perceived stimuli elicit stronger responses in higher visual and frontoparietal areas than those that fail to reach conscious awareness, the latter can still drive high-level brain and behavioral responses. We investigated whether unconscious processing of a masked natural image could facilitate subsequent conscious recognition of its degraded counterpart (a black-and-white “Mooney” image) presented many seconds later. We found that this is indeed the case, suggesting that conscious vision may be influenced by priors established by unconscious processing of a fleeting image. PMID:27595010

  20. Efficient gas-separation process to upgrade dilute methane stream for use as fuel

    DOEpatents

    Wijmans, Johannes G.; Merkel, Timothy C.; Lin, Haiqing; Thompson, Scott; Daniels, Ramin

    2012-03-06

    A membrane-based gas separation process for treating gas streams that contain methane in low concentrations. The invention involves flowing the stream to be treated across the feed side of a membrane and flowing a sweep gas stream, usually air, across the permeate side. Carbon dioxide permeates the membrane preferentially and is picked up in the sweep air stream on the permeate side; oxygen permeates in the other direction and is picked up in the methane-containing stream. The resulting residue stream is enriched in methane as well as oxygen and has an EMC value enabling it to be either flared or combusted by mixing with ordinary air.

  1. Mixing of Supersonic Streams

    NASA Technical Reports Server (NTRS)

    Hawk, C. W.; Landrum, D. B.; Muller, S.; Turner, M.; Parkinson, D.

    1998-01-01

    The Strutjet approach to Rocket Based Combined Cycle (RBCC) propulsion depends upon fuel-rich flows from the rocket nozzles and turbine exhaust products mixing with the ingested air for successful operation in the ramjet and scramjet modes. It is desirable to delay this mixing process in the air-augmented mode of operation present during low speed flight. A model of the Strutjet device has been built and is undergoing test to investigate the mixing of the streams as a function of distance from the Strutjet exit plane during simulated low speed flight conditions. Cold flow testing of a 1/6 scale Strutjet model is underway and nearing completion. Planar Laser Induced Fluorescence (PLIF) diagnostic methods are being employed to observe the mixing of the turbine exhaust gas with the gases from both the primary rockets and the ingested air simulating low speed, air augmented operation of the RBCC. The ratio of the pressure in the turbine exhaust duct to that in the rocket nozzle wall at the point of their intersection is the independent variable in these experiments. Tests were accomplished at values of 1.0, 1.5 and 2.0 for this parameter. Qualitative results illustrate the development of the mixing zone from the exit plane of the model to a distance of about 19 equivalent rocket nozzle exit diameters downstream. These data show the mixing to be confined in the vertical plane for all cases, The lateral expansion is more pronounced at a pressure ratio of 1.0 and suggests that mixing with the ingested flow would be likely beginning at a distance of 7 nozzle exit diameters downstream of the nozzle exit plane.

  2. Mixing of Supersonic Streams

    NASA Technical Reports Server (NTRS)

    Hawk, C. W.; Landrum, D. B.; Muller, S.; Turner, M.; Parkinson, D.

    1998-01-01

    The Strutjet approach to Rocket Based Combined Cycle (RBCC) propulsion depends upon fuel-rich flows from the rocket nozzles and turbine exhaust products mixing with the ingested air for successful operation in the ramjet and scramjet modes. It is desirable to delay this mixing process in the air-augmented mode of operation present during low speed flight. A model of the Strutjet device has been built and is undergoing test to investigate the mixing of the streams as a function of distance from the Strutjet exit plane during simulated low speed flight conditions. Cold flow testing of a 1/6 scale Strutjet model is underway and nearing completion. Planar Laser Induced Fluorescence (PLIF) diagnostic methods are being employed to observe the mixing of the turbine exhaust gas with the gases from both the primary rockets and the ingested air simulating low speed, air augmented operation of the RBCC. The ratio of the pressure in the turbine exhaust duct to that in the rocket nozzle wall at the point of their intersection is the independent variable in these experiments. Tests were accomplished at values of 1.0, 1.5 and 2.0 for this parameter. Qualitative results illustrate the development of the mixing zone from the exit plane of the model to a distance of about 10 rocket nozzle exit diameters downstream. These data show the mixing to be confined in the vertical plane for all cases, The lateral expansion is more pronounced at a pressure ratio of 1.0 and suggests that mixing with the ingested flow would be likely beginning at a distance of 7 nozzle exit diameters downstream of the nozzle exit plane.

  3. Primary zone air proportioner

    DOEpatents

    Cleary, Edward N. G.

    1982-10-12

    An air proportioner is provided for a liquid hydrocarbon fueled gas turbine of the type which is convertible to oil gas fuel and to coal gas fuel. The turbine includes a shell for enclosing the turbine, an air duct for venting air in said shell to a gasifier, and a fuel injector for injecting gasified fuel into the turbine. The air proportioner comprises a second air duct for venting air from the air duct for mixing with fuel from the gasifier. The air can be directly injected into the gas combustion basket along with the fuel from the injector or premixed with fuel from the gasifier prior to injection by the fuel injector.

  4. Heat transfer to two-phase air/water mixtures flowing in small tubes with inlet disequilibrium

    NASA Technical Reports Server (NTRS)

    Janssen, J. M.; Florschuetz, L. W.; Fiszdon, J. P.

    1986-01-01

    The cooling of gas turbine components was the subject of considerable research. The problem is difficult because the available coolant, compressor bleed air, is itself quite hot and has relatively poor thermophysical properties for a coolant. Injecting liquid water to evaporatively cool the air prior to its contact with the hot components was proposed and studied, particularly as a method of cooling for contingency power applications. Injection of a small quantity of cold liquid water into a relatively hot coolant air stream such that evaporation of the liquid is still in process when the coolant contacts the hot component was studied. No approach was found whereby heat transfer characteristics could be confidently predicted for such a case based solely on prior studies. It was not clear whether disequilibrium between phases at the inlet to the hot component section would improve cooling relative to that obtained where equilibrium was established prior to contact with the hot surface.

  5. 40 CFR 63.1093 - Does this subpart apply to my waste streams?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 11 2013-07-01 2013-07-01 false Does this subpart apply to my waste streams? 63.1093 Section 63.1093 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... streams? The waste stream provisions of this subpart apply to your waste streams if you own or operate...

  6. 40 CFR 63.1093 - Does this subpart apply to my waste streams?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 11 2014-07-01 2014-07-01 false Does this subpart apply to my waste streams? 63.1093 Section 63.1093 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... streams? The waste stream provisions of this subpart apply to your waste streams if you own or operate...

  7. 40 CFR 63.1093 - Does this subpart apply to my waste streams?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 11 2012-07-01 2012-07-01 false Does this subpart apply to my waste streams? 63.1093 Section 63.1093 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... streams? The waste stream provisions of this subpart apply to your waste streams if you own or operate...

  8. Mixing of Supersonic Streams

    NASA Technical Reports Server (NTRS)

    Hawk, Clark W.; Landrum, D. Brian; Spetman, David

    1997-01-01

    The Strutjet approach to Rocket Based Combined Cycle (RBCC) propulsion depends upon fuel-rich flows from the rocket nozzles and turbine exhaust products mixing with the ambient air for successful operation in the ramjet and scramjet modes. A model of the Strutjet device has been built and is undergoing test to investigate the mixing of the streams as a function of distance from the Strutjet exit plane. The modeling basis was centered on using convective Mach Number as the similarity parameter to establish correlation between subscale, cold flow tests and full scale, hot firing modes. This parameter has been used successfully to correlate supersonic shear layer growth rates. The experiment design includes hot (600 R) air as the rocket exhaust simulant and hot (760 R) carbon dioxide as the turbine exhaust gas simulant. The combination of gases and their elevated temperatures was required to achieve a convective Mach Number which matched the fall scale item design conditions. The carbon dioxide is seeded with Acetone to permit tracing of the mixing processes through Laser Induced Fluorescence (LIF) techniques. The experiment and its design will be discussed in detail. Both the rocket and turbine exhaust duct nozzles are of unique (square and rectangular) shape and the turbine exhaust e)dt intersects the rocket nozzle wall upstream of the exit. Cold flow testing with the individual nozzles has been conducted to ascertain their behavior in comparison to conventional flow theory. These data are presented.

  9. Eighteen Degree Water formation within the Gulf Stream during CLIMODE

    NASA Astrophysics Data System (ADS)

    Joyce, Terrence M.; Thomas, Leif N.; Dewar, William K.; Girton, James B.

    2013-07-01

    Analysis of wintertime CLIMODE data for 2007 indicates that a substantial portion of new Eighteen Degree Water (EDW) is likely ventilated within the eastward flowing Gulf Stream (GS) between 67°W and 52°W longitudes, possibly exceeding that formed elsewhere in the northern Sargasso Sea. Use of some global air-sea interaction data sets applied to the study region for Feb/Mar of 2007 indicate that this winter may have been anomalously energetic in air-sea exchange compared to the mean of the prior 19 yr. The largest heat and freshwater fluxes found directly over the meandering warm core of the Gulf Stream are capable of removing most of the subtropical heat anomaly of the GS, but cross-frontal fluxes of salinity are required to account for the observed regional salinity structure. An isopycnal diffusivity of ˜100 m2 s-1 is inferred from the salinity balance. This mixing would also account for the observation that EDW formed in the GS is slightly fresher than that formed in northern Sargasso Sea. The lateral flux of heat across the GS north wall also acts to cool the resulting EDW water, but the heat balance for EDW production is largely determined from GS advection and air-sea fluxes, in contrast to salinity. Based on oxygen saturation data, we estimate that 1.8-3.0 Sv-yr of new EDW is formed in the GS for the winter of 2007. EDW originating from the GS is generated in a separate location from where it is accumulated in the northern Sargasso Sea. This manner of EDW formation will produce unique characteristics of EDW found in the northern Sargasso Sea: ones that differ in T/S properties from that formed south of the GS under the more traditional 1D, cooling-driven convection process.

  10. Retrospective analysis of the response of soil and stream chemistry of a northern forest ecosystem to atmospheric emission controls from the 1970 and 1990 Amendments of the Clean Air Act.

    PubMed

    Gbondo-Tugbawa, Solomon S; Driscoll, Charles T

    2002-11-15

    The 1970 and 1990 Amendments of the Clean Air Act (CAAA) have resulted in a decline in acidic deposition in the northeastern United States. Results from the application of a biogeochemical model (PnET-BGC) at the Hubbard Brook Experimental Forest in New Hampshire suggest that, without the implementation of the CAAAs, soil base saturation and soil solution molar Ca/Al ratio would decrease to values below 6% and 1.0, respectively, while S would continue to accumulate in organic matter and adsorbed pools at rates of 2 and 3 kg of S ha(-1) yr(-1), respectively. This scenario of conditions without the CAAAs was projected to result in higher stream concentrations of SO4(2-), NO3-, and Ca2+; monomeric Al; pH below 4.8; and acid-neutralizing capacity (ANC) less than -15 microequiv L(-1). The implementation of the CAAAs has led to a slight improvement in the soil base saturation, while recovery of soil solution Ca/Al cannot be fully assessed because of variability in observed values. Our evaluation of the relative benefits of the 1970 and 1990 CAAAs indicate that although the magnitude of the cumulative decrease in strong acid deposition was greater following the 1970 CAAA as compared to the 1990 CAAA, the extent of ecosystem recovery relative to the changes in acidic deposition suggests that the 1990 CAAA was also beneficial. The slow recovery rates might be the result of a legacy of chemical effects of acidic deposition for the last 150 years and suggests that additional controls in emissions might be required to show significant changes.

  11. Menarche: Prior Knowledge and Experience.

    ERIC Educational Resources Information Center

    Skandhan, K. P.; And Others

    1988-01-01

    Recorded menstruation information among 305 young women in India, assessing the differences between those who did and did not have knowledge of menstruation prior to menarche. Those with prior knowledge considered menarche to be a normal physiological function and had a higher rate of regularity, lower rate of dysmenorrhea, and earlier onset of…

  12. The Importance of Prior Knowledge.

    ERIC Educational Resources Information Center

    Cleary, Linda Miller

    1989-01-01

    Recounts a college English teacher's experience of reading and rereading Noam Chomsky, building up a greater store of prior knowledge. Argues that Frank Smith provides a theory for the importance of prior knowledge and Chomsky's work provided a personal example with which to interpret and integrate that theory. (RS)

  13. Air conditioning system

    DOEpatents

    Lowenstein, Andrew; Miller, Jeffrey; Gruendeman, Peter; DaSilva, Michael

    2005-02-01

    An air conditioner comprises a plurality of plates arranged in a successively stacked configuration with portions thereof having a spaced apart arrangement, and defining between successive adjacent pairs of plates at the spaced apart portions a first and second series of discrete alternating passages wherein a first air stream is passed through the first series of passages and a second air stream is passed through the second series of passages; and said stacked configuration of plates forming integrally therewith a liquid delivery means for delivering from a source a sufficient quantity of a liquid to the inside surfaces of the first series of fluid passages in a manner which provides a continuous flow of the liquid from a first end to a second end of the plurality of plates while in contact with the first air stream.

  14. Winter stream temperature in the rain-on-snow zone of the Pacific Northwest: influences of hillslope runoff and transient snow cover

    NASA Astrophysics Data System (ADS)

    Leach, J. A.; Moore, R. D.

    2014-02-01

    Stream temperature dynamics during winter are less well studied than summer thermal regimes, but the winter season thermal regime can be critical for fish growth and development in coastal catchments. The winter thermal regimes of Pacific Northwest headwater streams, which provide vital winter habitat for salmonids and their food sources, may be particularly sensitive to changes in climate because they can remain ice-free throughout the year and are often located in rain-on-snow zones. This study examined winter stream temperature patterns and controls in small headwater catchments within the rain-on-snow zone at the Malcolm Knapp Research Forest, near Vancouver, British Columbia, Canada. Two hypotheses were addressed by this study: (1) winter stream temperatures are primarily controlled by advective fluxes associated with runoff processes and (2) stream temperatures should be depressed during rain-on-snow events, compared to rain-on-bare-ground events, due to the cooling effect of rain passing through the snowpack prior to infiltrating the soil or being delivered to the stream as saturation-excess overland flow. A reach-scale energy budget analysis of two winter seasons revealed that the advective energy input associated with hillslope runoff overwhelms vertical energy exchanges (net radiation, sensible and latent heat fluxes, bed heat conduction, and stream friction) and hyporheic energy fluxes during rain and rain-on-snow events. Historical stream temperature data and modelled snowpack dynamics were used to explore the influence of transient snow cover on stream temperature over 13 winters. When snow was not present, daily stream temperature during winter rain events tended to increase with increasing air temperature. However, when snow was present, stream temperature was capped at about 5 °C, regardless of air temperature. The stream energy budget modelling and historical analysis support both of our hypotheses. A key implication is that climatic warming may

  15. Dynamical Modelling of Meteoroid Streams

    NASA Astrophysics Data System (ADS)

    Clark, David; Wiegert, P. A.

    2012-10-01

    Accurate simulations of meteoroid streams permit the prediction of stream interaction with Earth, and provide a measure of risk to Earth satellites and interplanetary spacecraft. Current cometary ejecta and meteoroid stream models have been somewhat successful in predicting some stream observations, but have required questionable assumptions and significant simplifications. Extending on the approach of Vaubaillon et al. (2005)1, we model dust ejection from the cometary nucleus, and generate sample particles representing bins of distinct dynamical evolution-regulating characteristics (size, density, direction, albedo). Ephemerides of the sample particles are integrated and recorded for later assignment of frequency based on model parameter changes. To assist in model analysis we are developing interactive software to permit the “turning of knobs” of model parameters, allowing for near-real-time 3D visualization of resulting stream structure. With this tool, we will revisit prior assumptions made, and will observe the impact of introducing non-uniform cometary surface attributes and temporal activity. The software uses a single model definition and implementation throughout model verification, sample particle bin generation and integration, and analysis. It supports the adjustment with feedback of both independent and independent model values, with the intent of providing an interface supporting multivariate analysis. Propagations of measurement uncertainties and model parameter precisions are tracked rigorously throughout. We maintain a separation of the model itself from the abstract concepts of model definition, parameter manipulation, and real-time analysis and visualization. Therefore we are able to quickly adapt to fundamental model changes. It is hoped the tool will also be of use in other solar system dynamics problems. 1 Vaubaillon, J.; Colas, F.; Jorda, L. (2005) A new method to predict meteor showers. I. Description of the model. Astronomy and

  16. Regex-Stream

    SciTech Connect

    Goodall, John

    2012-09-01

    Log files are typically semi-or un-structured. To be useable, they need to be parsed into a standard, structured format. Regex-Stream facilitates parsing text files into structured data (JSON) in streams of data.

  17. Saving Our Streams.

    ERIC Educational Resources Information Center

    Firehock, Karen

    1993-01-01

    Presents an Izaak Walton League of America's Save Our Streams (SOS) program that teaches citizens how to protect streams. This organization provides activities for families, school groups, scout troops, 4-H clubs and other youth organizations. (MCO)

  18. Prioritized Contact Transport Stream

    NASA Technical Reports Server (NTRS)

    Hunt, Walter Lee, Jr. (Inventor)

    2015-01-01

    A detection process, contact recognition process, classification process, and identification process are applied to raw sensor data to produce an identified contact record set containing one or more identified contact records. A prioritization process is applied to the identified contact record set to assign a contact priority to each contact record in the identified contact record set. Data are removed from the contact records in the identified contact record set based on the contact priorities assigned to those contact records. A first contact stream is produced from the resulting contact records. The first contact stream is streamed in a contact transport stream. The contact transport stream may include and stream additional contact streams. The contact transport stream may be varied dynamically over time based on parameters such as available bandwidth, contact priority, presence/absence of contacts, system state, and configuration parameters.

  19. Are cosmological neutrinos free-streaming?

    SciTech Connect

    Basboell, Anders; Bjaelde, Ole Eggers; Hannestad, Steen; Raffelt, Georg G.

    2009-02-15

    Precision data from cosmology suggest neutrinos stream freely and hence interact very weakly around the epoch of recombination. We study this issue in a simple framework where neutrinos recouple instantaneously and stop streaming freely at a redshift z{sub i}. The latest cosmological data imply z{sub i} < or approx. 1500, the exact constraint depending somewhat on the assumed prior on z{sub i}. This bound can be translated into a bound on the coupling strength between neutrinos and majoronlike particles.

  20. Air stripping industrial wastewater

    SciTech Connect

    Lamarre, B.; Shearouse, D.

    1994-09-01

    Industrial wastewater can be quickly, efficiently and economically treated using air strippers. Air stripping removes a range of volatile and semi-volatile contaminants from water. And the performance of various types and sizes of tray-type air stripper for treating contaminated water now is highly predictable because of laboratory studies. Air stripping can be a fast, efficient and economical approach to treating industrial wastewater. However, since every industrial wastewater stream is unique, each must be evaluated to determine its constituents, its potentially adverse effects on treatability, and any pretreatment steps necessary to ensure desired results. The general principles of air stripping are simple. In an air stripper, the surfaces area of a film of contaminated water is maximized while air is directed across it. Contaminants at the air/water interface volatilize and are discharged to the atmosphere or to an off-gas treatment system.

  1. The Puzzling Ophiuchus Stream

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-01-01

    Dwarf galaxies or globular clusters orbiting the Milky Way can be pulled apart by tidal forces, leaving behind a trail of stars known as a stellar stream. One such trail, the Ophiuchus stream, has posed a serious dynamical puzzle since its discovery. But a recent study has identified four stars that might help resolve this streams mystery.Conflicting TimescalesThe stellar stream Ophiuchus was discovered around our galaxy in 2014. Based on its length, which appears to be 1.6 kpc, we can calculate the time that has passed since its progenitor was disrupted and the stream was created: ~250 Myr. But the stars within it are ~12 Gyr old, and the stream orbits the galaxy with a period of ~350 Myr.Given these numbers, we can assume that Ophiuchuss progenitor completed many orbits of the Milky Way in its lifetime. So why would it only have been disrupted 250 million years ago?Fanning StreamLed by Branimir Sesar (Max Planck Institute for Astronomy), a team of scientists has proposed an idea that might help solve this puzzle. If the Ophiuchus stellar stream is on a chaotic orbit common in triaxial potentials, which the Milky Ways may be then the stream ends can fan out, with stars spreading in position and velocity.The fanned part of the stream, however, would be difficult to detect because of its low surface brightness. As a result, the Ophiuchus stellar stream could actually be longer than originally measured, implying that it was disrupted longer ago than was believed.Search for Fan StarsTo test this idea, Sesar and collaborators performed a search around the ends of the stream, looking for stars thatare of the right type to match the stream,are at the predicted distance of the stream,are located near the stream ends, andhave velocities that match the stream and dont match the background halo stars.Histogram of the heliocentric velocities of the 43 target stars. Six stars have velocities matching the stream velocity. Two of these are located in the main stream; the other

  2. Determination of stream reaeration coefficients by use of tracers

    USGS Publications Warehouse

    Kilpatrick, F.A.; Rathbun, R.E.; Yotsukura, Nobuhiro; Parker, G.W.; DeLong, L.L.

    1987-01-01

    Stream reaeration is the physical absorption of oxygen from the atmosphere by a flowing stream. This is the primary process by which a stream replenishes the oxygen consumed in the biodegradation of organic wastes. Prior to 1965, reaeration rate coefficients could be estimated only by indirect methods. In 1965, a direct method of measuring stream reaeration coefficients was developed in which a radioactive tracer gas was injected into a stream--the tracer gas being desorbed from the stream inversely to how oxygen would be absorbed. The technique has since been modified by substituting hydrocarbon gases for the radioactive tracer gas. The slug-injection and constant-rate injection methods of performing gas tracer desorption measurements are described. Emphasis is on the use of rhodamine WT dye as a relatively conservative tracer and propane as the nonconservative gas tracer, on planning field tests, methods of injection, sampling and analysis, and computational techniques to compute desorption and reaeration coefficients. (Author 's abstract)

  3. Method for removing acid gases from a gaseous stream

    DOEpatents

    Gorin, Everett; Zielke, Clyde W.

    1981-01-01

    In a process for hydrocracking a heavy aromatic polynuclear carbonaceous feedstock containing reactive alkaline constituents to produce liquid hydrocarbon fuels boiling below about 475.degree. C. at atmospheric pressure by contacting the feedstock with hydrogen in the presence of a molten metal halide catalyst, thereafter separating a gaseous stream containing hydrogen, at least a portion of the hydrocarbon fuels and acid gases from the molten metal halide and regenerating the molten metal halide, thereby producing a purified molten metal halide stream for recycle to the hydrocracking zone, an improvement comprising; contacting the gaseous acid gas, hydrogen and hydrocarbon fuels-containing stream with the feedstock containing reactive alkaline constituents to remove acid gases from the acid gas containing stream. Optionally at least a portion of the hydrocarbon fuels are separated from gaseous stream containing hydrogen, hydrocarbon fuels and acid gases prior to contacting the gaseous stream with the feedstock.

  4. Components of Visual Prior Entry

    ERIC Educational Resources Information Center

    Schneider, Keith A.; Bavelier, Daphne

    2003-01-01

    The prior entry hypothesis contends that attention accelerates sensory processing, shortening the time to perception. Typical observations supporting the hypothesis may be explained equally well by response biases, changes in decision criteria, or sensory facilitation. In a series of experiments conducted to discriminate among the potential…

  5. Prior Distributions on Symmetric Groups

    ERIC Educational Resources Information Center

    Gupta, Jayanti; Damien, Paul

    2005-01-01

    Fully and partially ranked data arise in a variety of contexts. From a Bayesian perspective, attention has focused on distance-based models; in particular, the Mallows model and extensions thereof. In this paper, a class of prior distributions, the "Binary Tree," is developed on the symmetric group. The attractive features of the class are: it…

  6. Gas stream purifier

    NASA Technical Reports Server (NTRS)

    Adam, Steven J.

    1994-01-01

    A gas stream purifier has been developed that is capable of removing corrosive acid, base, solvent, organic, inorganic, and water vapors as well as particulates from an inert mixed gas stream using only solid scrubbing agents. This small, lightweight purifier has demonstrated the ability to remove contaminants from an inert gas stream with a greater than 99 percent removal efficiency. The Gas Stream Purifier has outstanding market and sales potential in manufacturing, laboratory and science industries, medical, automotive, or any commercial industry where pollution, contamination, or gas stream purification is a concern. The purifier was developed under NASA contract NAS9-18200 Schedule A for use in the international Space Station. A patent application for the Gas Stream Purifier is currently on file with the United States Patent and Trademark Office.

  7. Dynamics of meteor streams

    NASA Technical Reports Server (NTRS)

    Babadjanov, P. B.; Obrubov, Yu. U.

    1987-01-01

    The overwhelming majority of meteor streams are generally assumed to be formed due to the decay of comets. The most effective process of the release of solid particles from a cometary nucleus is their ejection by sublimating gases when the comet approaches the Sun. The results of investigation of the Geminids and Quadrantids meteor stream evolution show that under the influence of planetary perturbations, the stream may originally be flat but then thicken depending on the variation range of orbital inclinations. Eventually, due to planetary perturbations, a meteor stream may take such a shape as to cause the start of several active showers at different solar longitudes.

  8. Inventory of miscellaneous streams

    SciTech Connect

    Lueck, K.J.

    1995-09-01

    On December 23, 1991, the US Department of Energy, Richland Operations Office (RL) and the Washington State Department of Ecology (Ecology) agreed to adhere to the provisions of the Department of Ecology Consent Order. The Consent Order lists the regulatory milestones for liquid effluent streams at the Hanford Site to comply with the permitting requirements of Washington Administrative Code. The RL provided the US Congress a Plan and Schedule to discontinue disposal of contaminated liquid effluent into the soil column on the Hanford Site. The plan and schedule document contained a strategy for the implementation of alternative treatment and disposal systems. This strategy included prioritizing the streams into two phases. The Phase 1 streams were considered to be higher priority than the Phase 2 streams. The actions recommended for the Phase 1 and 2 streams in the two reports were incorporated in the Hanford Federal Facility Agreement and Consent Order. Miscellaneous Streams are those liquid effluents streams identified within the Consent Order that are discharged to the ground but are not categorized as Phase 1 or Phase 2 Streams. This document consists of an inventory of the liquid effluent streams being discharged into the Hanford soil column.

  9. ENGINEERING BULLETIN: AIR STRIPPING OF AQUEOUS SOLUTIONS

    EPA Science Inventory

    Air striding is a means to transfer contaminants from aqueous solutions to air. ontaminants are not destroyed by air stripping but are physically separated from the aqueous solutions. ontaminant vapors are transferred into the air stream and, if necessary, can be treated by incin...

  10. Tracking the Magellanic Stream(s)

    NASA Astrophysics Data System (ADS)

    Nidever, D. L.; Majewski, S. R.; Burton, W. B.

    2005-12-01

    We use the Leiden-Argentine-Bonn (LAB) all-sky HI survey to explore the HI Magellanic Stream. An automated Gaussian analysis program was run on the southern sky for b<-20 degrees and the results give the clearest picture of the Magellanic Stream to date. While we also find that the Magellanic Stream is composed of two primary filaments, as first indicated by Putman et al. (2003), with a LAB velocity precision of 1 km/s we are able to track the two filaments all of the way from their origin in the Magellanic Clouds to their endpoint 100 degrees away. One of the filaments is found to eminate from the 30 Dor region of the LMC. The filaments provide a new tool to study the dynamics of the Magellanic Clouds.

  11. Predicting a prior for Planck

    SciTech Connect

    Hertog, Thomas

    2014-02-01

    The quantum state of the universe combined with the structure of the landscape potential implies a prior that specifies predictions for observations. We compute the prior for CMB related observables given by the no-boundary wave function (NBWF) in a landscape model that includes a range of inflationary patches representative of relatively simple single-field models. In this landscape the NBWF predicts our classical cosmological background emerges from a region of eternal inflation associated with a plateau-like potential. The spectra of primordial fluctuations on observable scales are characteristic of concave potentials, in excellent agreement with the Planck data. By contrast, alternative theories of initial conditions that strongly favor inflation at high values of the potential are disfavored by observations in this landscape.

  12. Adopt a Stream.

    ERIC Educational Resources Information Center

    Friends of Environmental Education Society of Alberta (Edmonton).

    This environmental education program is designed to increase awareness among junior high school students of stream ecosystems and those habitats which comprise the ecosystems adjacent to streams. The teaching content of the manual is presented in two major sections. The first section provides information and background material for the group…

  13. WADEABLE STREAMS ASSESSMENT

    EPA Science Inventory

    This Wadeable Streams Assessment (WSA) provides the first statistically defensible summary of the condition of the nation’s streams and small rivers, which are so integrally tied to our history. This report brings the results of this ground-breaking study to the American public....

  14. River and Stream Pollution

    MedlinePlus

    ... Pollution Dirt Dirt is a big cause of pollution in our rivers and streams. Rain washes dirt into streams and rivers. Dirt can smother fish and other animals that live in the water. If plants can't get enough sunlight because ...

  15. Citrus waste stream utilization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Waste streams, generated during fruit processing, consist of solid fruit residues in addition to liquid waste streams from washing operations which must be handled in an environmentally acceptable manner. Unsound fruit from packing houses are usually sent off to be processed for juice and the solid ...

  16. Downstream Propagation of Thermal Pollution in Urban Streams

    NASA Astrophysics Data System (ADS)

    Somers, K. A.; Urban, D. L.; Bernhardt, E. S.; Losordo, M.

    2011-12-01

    Cities create "heat islands" with air temperatures up to 12 degrees C greater than surrounding areas and impervious surface temperatures reaching 50 degrees C greater than the air. Streams that drain urban areas tend to be hotter at baseflow due to warmer air temperatures and decreased riparian canopy cover. Further, urban stormflow routes precipitation over hot impervious surfaces and through storm drains directly into streams, creating rapid changes in stream temperatures. The resulting alterations in stream thermal regimes directly stress aquatic organisms and indirectly lead to changes in stream microbial activity and dissolved oxygen concentrations. To date, there has been little work done to understand how urban heating of streams propagates downstream from thermal pollution sources. In response to this lack, we used a fiber optic distributed temperature sensor as well as multiple individual temperature loggers to measure high spatiotemporal resolution patterns of stream temperature along 1.5 km of Mud Creek in Durham, NC. Mud Creek originates in the storm drains of a suburban neighborhood, where high-density residential complexes with large amounts of impervious surface are connected directly to the stream. The stream flows in a confined channel alongside apartment complexes for 0.5 km before entering a protected forest area. At baseflow, we found temperature was heterogeneous and explained primarily by canopy openness, rather than the amount of development upstream of the location. During summer stormflows, stream temperatures became more homogeneous and increased by up to 4 degrees C due to runoff at the top of the reach. These peak temperatures were dampened to only 2 degrees C increases after 1 km of travel through mature forest. In contrast, a fully forested tributary to Mud Creek decreased in temperature for the same storm events. This spatial propagation of stormflow heat pulses will substantially limit our ability to protect urban stream ecosystems.

  17. Ramification of stream networks.

    PubMed

    Devauchelle, Olivier; Petroff, Alexander P; Seybold, Hansjörg F; Rothman, Daniel H

    2012-12-18

    The geometric complexity of stream networks has been a source of fascination for centuries. However, a comprehensive understanding of ramification--the mechanism of branching by which such networks grow--remains elusive. Here we show that streams incised by groundwater seepage branch at a characteristic angle of 2π/5 = 72°. Our theory represents streams as a collection of paths growing and bifurcating in a diffusing field. Our observations of nearly 5,000 bifurcated streams growing in a 100 km(2) groundwater field on the Florida Panhandle yield a mean bifurcation angle of 71.9° ± 0.8°. This good accord between theory and observation suggests that the network geometry is determined by the external flow field but not, as classical theories imply, by the flow within the streams themselves.

  18. Distribution and abundance of stream fishes in relation to barriers: implications for monitoring stream recovery after barrier removal

    USGS Publications Warehouse

    Zydlewski, Joseph; Coghlan Jr., Stephen M.; Gardner, C.; Saunders, R.

    2011-01-01

    Dams are ubiquitous in coastal regions and have altered stream habitats and the distribution and abundance of stream fishes in those habitats by disrupting hydrology, temperature regime and habitat connectivity. Dam removal is a common restoration tool, but often the response of the fish assemblage is not monitored rigorously. Sedgeunkedunk Stream, a small tributary to the Penobscot River (Maine, USA), has been the focus of a restoration effort that includes the removal of two low-head dams. In this study, we quantified fish assemblage metrics along a longitudinal gradient in Sedgeunkedunk Stream and also in a nearby reference stream. By establishing pre-removal baseline conditions and associated variability and the conditions and variability immediately following removal, we can characterize future changes in the system associated with dam removal. Over 2 years prior to dam removal, species richness and abundance in Sedgeunkedunk Stream were highest downstream of the lowest dam, lowest immediately upstream of that dam and intermediate farther upstream; patterns were similar in the reference stream. Although seasonal and annual variation in metrics within each site was substantial, the overall upstream-to-downstream pattern along the stream gradient was remarkably consistent prior to dam removal. Immediately after dam removal, we saw significant decreases in richness and abundance downstream of the former dam site and a corresponding increase in fish abundance upstream of the former dam site. No such changes occurred in reference sites. Our results show that by quantifying baseline conditions in a small stream before restoration, the effects of stream restoration efforts on fish assemblages can be monitored successfully. These data set the stage for the long-term assessment of Sedgeunkedunk Stream and provide a simple methodology for assessment in other restoration projects.

  19. Hydrology of the Chicod Creek basin, North Carolina, prior to channel improvements

    USGS Publications Warehouse

    Simmons, Clyde E.; Aldridge, Mary C.

    1980-01-01

    Extensive modification and excavation of stream channels in the 6-square mile Chicod Creek basin began in mid-1979 to reduce flooding and improve stream runoff conditions. The effects of channel improvements on this Coastal Pain basin 's hydrology will be determined from data collected prior to, during, and for several years following channel alternations. This report summarizes the findings of data collected prior to these improvements. During the 3-year study period, flow data collected from four stream gaging stations in the basin show that streams are dry approximately 10 percent of the time. Chemical analyses of water samples from the streams and from eight shallow groundwater observation wells indicate that water discharge from the surficial aquifer is the primary source of streamflow during rainless periods. Concentrations of Kjeldahl nitrogen, total nitrogen, and total phosphorus were often 5 to 10 times greater at Chicod Creek sites than those at nearby baseline sites. It is probable that runoff from farming and livestock operations contributes significantly to these elevated concentrations in Chicod Creek. The only pesticides detected in stream water were low levels of DDT and dieldrin, which occurred during storm runoff. A much wider range of pesticides, however, are found associated with streambed materials. The ratio of fecal coliform counts to those of fecal streptococcus indicate that the streams receive fecal wastes from livestock and poultry operations.

  20. NOx reduction in combustion with concentrated coal streams and oxygen injection

    DOEpatents

    Kobayashi, Hisashi; Bool, III, Lawrence E.; Snyder, William J.

    2004-03-02

    NOx formation in the combustion of solid hydrocarbonaceous fuel such as coal is reduced by obtaining, from the incoming feed stream of fuel solids and air, a stream having a ratio of fuel solids to air that is higher than that of the feed steam, and injecting the thus obtained stream and a small amount of oxygen to a burner where the fuel solids are combusted.

  1. Prediction of stream volatilization coefficients

    USGS Publications Warehouse

    Rathbun, Ronald E.

    1990-01-01

    Equations are developed for predicting the liquid-film and gas-film reference-substance parameters for quantifying volatilization of organic solutes from streams. Molecular weight and molecular-diffusion coefficients of the solute are used as correlating parameters. Equations for predicting molecular-diffusion coefficients of organic solutes in water and air are developed, with molecular weight and molal volume as parameters. Mean absolute errors of prediction for diffusion coefficients in water are 9.97% for the molecular-weight equation, 6.45% for the molal-volume equation. The mean absolute error for the diffusion coefficient in air is 5.79% for the molal-volume equation. Molecular weight is not a satisfactory correlating parameter for diffusion in air because two equations are necessary to describe the values in the data set. The best predictive equation for the liquid-film reference-substance parameter has a mean absolute error of 5.74%, with molal volume as the correlating parameter. The best equation for the gas-film parameter has a mean absolute error of 7.80%, with molecular weight as the correlating parameter.

  2. Twitter Stream Archiver

    SciTech Connect

    Steed, Chad Allen

    2014-07-01

    The Twitter Archiver system allows a user to enter their Twitter developer account credentials (obtained separately from the Twitter developer website) and read from the freely available Twitter sample stream. The Twitter sample stream provides a random sample of the overall volume of tweets that are contributed by users to the system. The Twitter Archiver system consumes the stream and serializes the information to text files at some predefined interval. A separate utility reads the text files and creates a searchable index using the open source Apache Lucene text indexing system.

  3. Twitter Stream Archiver

    2014-07-01

    The Twitter Archiver system allows a user to enter their Twitter developer account credentials (obtained separately from the Twitter developer website) and read from the freely available Twitter sample stream. The Twitter sample stream provides a random sample of the overall volume of tweets that are contributed by users to the system. The Twitter Archiver system consumes the stream and serializes the information to text files at some predefined interval. A separate utility reads themore » text files and creates a searchable index using the open source Apache Lucene text indexing system.« less

  4. Evidence for atmospheric carbon dioxide variability over the Gulf Stream

    NASA Technical Reports Server (NTRS)

    Bufton, J. L.

    1984-01-01

    Two airborne surveys of atmospheric carbon dioxide concentration have been conducted over the Gulf Stream off the east coast of Virginia and North Carolina on September 7-8, 1983. In situ CO2 data were acquired at an aircraft altitude of 300 m on trajectories that transcected the Gulf Stream near 36 deg N 73 deg W. Data show evidence of a CO2 concentration increase by 4 ppm to 15 ppm above the nominal atmospheric background value of 345 ppm. These enhanced values were associated with the physical location of the Gulf Stream prior to the passage of a weak cold front.

  5. Investigating the monthly mean stream temperature dynamics

    NASA Astrophysics Data System (ADS)

    Gallice, Aurélien; Huwald, Hendrik; Schaefli, Bettina; Rinaldo, Andrea; Lehning, Michael

    2014-05-01

    Affecting the habitat suitability of many fish species, water temperature is a hydrological factor of great concern in the actual context of climate change. Despite more than 40 years of research on this topic, the impact of landscape on the dynamics of stream temperature is still not entirely understood. In the present study, we analyzed the monthly mean stream temperature measurements collected in 26 medium-sized catchments (3-300 km2) in Switzerland. While selecting the catchments, particular attention was given to cover a large range of different geomorphological conditions, especially regarding altitude, slope and aspect. Despite these differences, it was surprisingly found that the thermal regimes of almost all the investigated streams followed a same annual trend. Only the amplitude and the minimum value of this trend were observed to differ between the individual catchments. These two factors could be successfully related to geomorphological characteristics of the catchments using multi-linear regression. The shape of the annual trend was found to vary from one year to the other. This inter-annual variability was attributed to climate, based on the significant correlation between the annual trend and air temperature. As a result of the present study, we obtained a regression model to estimate the monthly mean stream temperature in ungauged catchments based on country-wide available geomorphological variables and the average of the monthly mean air temperature over Switzerland.

  6. Stochastic ice stream dynamics

    NASA Astrophysics Data System (ADS)

    Mantelli, Elisa; Bertagni, Matteo Bernard; Ridolfi, Luca

    2016-08-01

    Ice streams are narrow corridors of fast-flowing ice that constitute the arterial drainage network of ice sheets. Therefore, changes in ice stream flow are key to understanding paleoclimate, sea level changes, and rapid disintegration of ice sheets during deglaciation. The dynamics of ice flow are tightly coupled to the climate system through atmospheric temperature and snow recharge, which are known exhibit stochastic variability. Here we focus on the interplay between stochastic climate forcing and ice stream temporal dynamics. Our work demonstrates that realistic climate fluctuations are able to (i) induce the coexistence of dynamic behaviors that would be incompatible in a purely deterministic system and (ii) drive ice stream flow away from the regime expected in a steady climate. We conclude that environmental noise appears to be crucial to interpreting the past behavior of ice sheets, as well as to predicting their future evolution.

  7. Stochastic ice stream dynamics.

    PubMed

    Mantelli, Elisa; Bertagni, Matteo Bernard; Ridolfi, Luca

    2016-08-01

    Ice streams are narrow corridors of fast-flowing ice that constitute the arterial drainage network of ice sheets. Therefore, changes in ice stream flow are key to understanding paleoclimate, sea level changes, and rapid disintegration of ice sheets during deglaciation. The dynamics of ice flow are tightly coupled to the climate system through atmospheric temperature and snow recharge, which are known exhibit stochastic variability. Here we focus on the interplay between stochastic climate forcing and ice stream temporal dynamics. Our work demonstrates that realistic climate fluctuations are able to (i) induce the coexistence of dynamic behaviors that would be incompatible in a purely deterministic system and (ii) drive ice stream flow away from the regime expected in a steady climate. We conclude that environmental noise appears to be crucial to interpreting the past behavior of ice sheets, as well as to predicting their future evolution. PMID:27457960

  8. Urban Stream Ecology

    EPA Science Inventory

    Urban watersheds characteristically have high impervious surface cover, resulting in high surface runoff and low infiltration following storms. In response, urban streams experience “flashy” stormflows, reduced baseflows, bank erosion, channel widening, and sedimentation. Urban ...

  9. Discontinuous ephemeral streams

    NASA Astrophysics Data System (ADS)

    Bull, William B.

    1997-07-01

    Many ephemeral streams in western North America flowed over smooth valley floors before transformation from shallow discontinuous channels into deep arroyos. These inherently unstable streams of semiarid regions are sensitive to short-term climatic changes, and to human impacts, because hillslopes supply abundant sediment to infrequent large streamflow events. Discontinuous ephemeral streams appear to be constantly changing as they alternate between two primary modes of operation; either aggradation or degradation may become dominant. Attainment of equilibrium conditions is brief. Disequilibrium is promoted by channel entrenchment that causes the fall of local base level, and by deposition of channel fans that causes the rise of local base level. These opposing base-level processes in adjacent reaches are maintained by self-enhancing feedback mechanisms. The threshold between erosion and deposition is crossed when aggradational or degradational reaches shift upstream or downstream. Extension of entrenched reaches into channel fans tends to create continuous arroyos. Upvalley migration of fan apexes tends to create depositional valley floors with few stream channels. Less than 100 years is required for arroyo cutting, but more than 500 years is required for complete aggradation of entrenched stream channels and valley floors. Discontinuous ephemeral streams have a repetitive sequence of streamflow characteristics that is as distinctive as sequences of meander bends or braided gravel bars in perennial rivers. The sequence changes from degradation to aggradation — headcuts concentrate sheetflow, a single trunk channel conveys flow to the apex of a channel fan, braided distributary channels end in an area of diverging sheetflow, and converging sheetflow drains to headcuts. The sequence is repeated at intervals ranging from 15 m for small streams to more than 10 km for large streams. Lithologic controls on the response of discontinuous ephemeral streams include: (1

  10. Replay-Stream

    SciTech Connect

    Goodall, John

    2012-12-01

    For testing and demonstration purposes, it is often necessary to replay saved network and log data. This library facilitates replaying these saved data streams. This module will take in a stream of JSON strings, read their specified timestamp field, and output according to the given criteria. This can include restricting output to a certain time range, and/or outputting the items with some delay based on their timestamp.

  11. Comparison of Mercury Mass Loading in Streams to Wet and Dry Atmospheric Deposition in Watersheds of the Western US: Evidence for Non-Atmospheric Mercury Sources

    NASA Astrophysics Data System (ADS)

    Domagalski, J. L.; Majewski, M. S.; Alpers, C. N.; Eckley, C.

    2015-12-01

    Many streams in the western United States (US) are listed as impaired by mercury (Hg), and it is important to understand the magnitudes of the various sources in order to implement management strategies. Atmospheric deposition of Hg and can be a major source of aquatic contamination, along with mine wastes, and other sources. Prior studies in the eastern US have shown that streams deliver less than 50% of the atmospherically deposited Hg on an annual basis. In this study, we compared annual stream Hg loads for 20 watersheds in the western US to measured wet and modeled dry deposition. Land use varies from undisturbed to mixed (agricultural, urban, forested, mining). Data from the Mercury Deposition Network was used to estimate Hg input from precipitation. Dry deposition was not directly measured, but can be modeled using the Community Multi-scale Air Quality model. At an undeveloped watershed in the Rocky Mountains, the ratio of stream Hg load to atmospheric deposition was 0.2 during a year of average precipitation. In contrast, at the Carson River in Nevada, with known Hg contamination from historical silver mining with Hg amalgamation, stream export exceeded atmospheric deposition by a factor of 60, and at a small Sierran watershed with gold mining, the ratio was 70. Larger watersheds with mixed land uses, tend to have lower ratios of stream export relative to atmospheric deposition suggesting storage of Hg. The Sacramento River was the largest watershed for which Hg riverine loads were available with an average ratio of stream Hg export to atmospheric deposition of 0.10. Although Hg was used in upstream historical mining operations, the downstream river Hg load is partially mitigated by reservoirs, which trap sediment. This study represents the first compilation of riverine Hg loads in comparison to atmospheric deposition on a regional scale; the approach may be useful in assessing the relative importance of atmospheric and non-atmospheric Hg sources.

  12. Taking Science On-air with Google+

    NASA Astrophysics Data System (ADS)

    Gay, P.

    2014-01-01

    Cost has long been a deterrent when trying to stream live events to large audiences. While streaming providers like UStream have free options, they include advertising and typically limit broadcasts to originating from a single location. In the autumn of 2011, Google premiered a new, free, video streaming tool -- Hangouts on Air -- as part of their Google+ social network. This platform allows up to ten different computers to stream live content to an unlimited audience, and automatically archives that content to YouTube. In this article we discuss best practices for using this technology to stream events over the internet.

  13. Regional and local scale modeling of stream temperatures and spatio-temporal variation in thermal sensitivities.

    PubMed

    Hilderbrand, Robert H; Kashiwagi, Michael T; Prochaska, Anthony P

    2014-07-01

    Understanding variation in stream thermal regimes becomes increasingly important as the climate changes and aquatic biota approach their thermal limits. We used data from paired air and water temperature loggers to develop region-scale and stream-specific models of average daily water temperature and to explore thermal sensitivities, the slopes of air-water temperature regressions, of mostly forested streams across Maryland, USA. The region-scale stream temperature model explained nearly 90 % of the variation (root mean square error = 0.957 °C), with the mostly flat coastal plain streams having significantly higher thermal sensitivities than the steeper highlands streams with piedmont streams intermediate. Model R (2) for stream-specific models was positively related to a stream's thermal sensitivity. Both the regional and the stream-specific air-water temperature regression models benefited from including mean daily discharge from regional gaging stations, but the degree of improvement declined as a stream's thermal sensitivity increased. Although catchment size had no relationship to thermal sensitivity, steeper streams or those with greater amounts of forest in their upstream watershed were less thermally sensitive. The subset of streams with three or more summers of temperature data exhibited a wide range of annual variation in thermal sensitivity at a site, with the variation not attributable to discharge, precipitation patterns, or physical attributes of streams or their watersheds. Our findings are a useful starting point to better understand patterns in stream thermal regimes. However, a more spatially and temporally comprehensive monitoring network should increase understanding of stream temperature variation and its controls as climatic patterns change.

  14. 46 CFR 76.13-90 - Installations contracted for prior to January 1, 1962.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... small spaces may be taken from the nearest stream supply line and shall be not less than 3/4-inch pipe... VESSELS FIRE PROTECTION EQUIPMENT Steam Smothering Systems § 76.13-90 Installations contracted for prior... be made to the same standard as the original installation. (2) The main pipes and their branches...

  15. From Headwater Streams to Rivers

    ERIC Educational Resources Information Center

    Cummins, Kenneth W.

    1977-01-01

    Presents generalizations regarding how running water systems change physically, chemically and biologically with stream order, i. e., from the tiny headwater streams (order 1) to those receiving first order headwater tributaries (order 2) and so on. Food chain diagrams respective of stream order are explained. Stream study projects are suggested.…

  16. Interpretation of groundwater age tracers (CFC-12, 14C, 4He) in a mining-influenced stream-aquifer system with transient recharge dynamics.

    NASA Astrophysics Data System (ADS)

    Bourke, Sarah; Cook, Peter; Kipfer, Rolf; Dogramaci, Shawan

    2014-05-01

    Interpretation of groundwater age tracers often requires consideration of the mixing of groundwater with varying residence times. Quantification of mixing can be approached through measurement of multiple groundwater age indicators with varying ranges of temporal sensitivity, and their interpretation using lumped parameter models. However, in systems altered by mining, where recharge mechanisms are highly transient in space and time, lumped parameter models do not adequately represent the complexity of the system. In the Pilbara region of Western Australia, water abstracted during dewatering of ore-body aquifers is disposed of by discharging it into ephemeral streams and allowing it to recharge the aquifer. Because this water is essentially being recycled, stable isotopes and chloride are not useful tracers of the impact of this dewatering discharge. In contrast, gas tracers that respond rapidly to exposure to the atmosphere are more useful tracers for constraining the influence of dewatering discharge on the aquifer water balance. In this study we measured CFC-12, 14C and noble gases in production wells and transects of piezometers perpendicular to the stream. Even in samples from wells screened over intervals of 1 m, we observe combinations of tracer concentrations that indicate mixing of groundwater with contrasting residence times. For example, all samples contained measureable CFC-12 concentrations, including those with appreciable terrigenic 4He. Interpretation of these data requires consideration of the history of mining activity in the area. Stream 14C activities, which now range from 50 to 75 pMC, are a function of the dewatering discharge, and are no longer in equilibrium with the atmosphere. As a result, groundwater that recharged prior to mining operations can have higher 14C activities than groundwater that recharged through the stream in the last 10 years. The dewatering discharge has caused the stream to transition from a disconnected ephemeral

  17. Fast acoustic streaming in standing waves: generation of an additional outer streaming cell.

    PubMed

    Reyt, Ida; Daru, Virginie; Bailliet, Hélène; Moreau, Solène; Valière, Jean-Christophe; Baltean-Carlès, Diana; Weisman, Catherine

    2013-09-01

    Rayleigh streaming in a cylindrical acoustic standing waveguide is studied both experimentally and numerically for nonlinear Reynolds numbers from 1 to 30 [Re(NL)=(U0/c0)(2)(R/δν)(2), with U0 the acoustic velocity amplitude at the velocity antinode, c0 the speed of sound, R the tube radius, and δν the acoustic boundary layer thickness]. Streaming velocity is measured by means of laser Doppler velocimetry in a cylindrical resonator filled with air at atmospheric pressure at high intensity sound levels. The compressible Navier-Stokes equations are solved numerically with high resolution finite difference schemes. The resonator is excited by shaking it along the axis at imposed frequency. Results of measurements and of numerical calculation are compared with results given in the literature and with each other. As expected, the axial streaming velocity measured and calculated agrees reasonably well with the slow streaming theory for small ReNL but deviates significantly from such predictions for fast streaming (ReNL>1). Both experimental and numerical results show that when ReNL is increased, the center of the outer streaming cells are pushed toward the acoustic velocity nodes until counter-rotating additional vortices are generated near the acoustic velocity antinodes.

  18. Consider an Ice Stream.

    NASA Astrophysics Data System (ADS)

    Bindschadler, R.

    2002-12-01

    Forty years ago, John Nye was one of the leaders who introduced the rigors of classical physics to glaciology. His elegant treatments frequently took advantage of the then recent discovery that ice could be approximated as a plastic material. With this viewpoint, Nye was able to explain the shape of ice sheets and glaciers, to predict the expected pattern of stress and velocity within a glacier, and to derive the advance and retreat of a glacier from the record of accumulation and ablation. These advances have given generations of glaciologists tools to interpret the excellent observational record of glacier behavior and variation. In the 1980s, glaciologist, weaned on these works of Nye and of other similarly adept colleagues, carried their lessons to West Antarctica to study ice streams, the vast conveyor belts of ice that discharged nearly as much Antarctic ice as the much larger East Antarctic ice sheet. Ice streams were a glaciological conundrum. Despite the gently sloping surface, these broad features roared along, moving fastest when the gravitational impetus was least. After two decades of research, ice streams still have not given up all their secrets, yet much is now known. Internal deformation is negligible. Basal friction is frequently nil leaving the shattered margins as the primary means to avoid rapid wastage of the ice sheet. Within the margins, the resistive force results from a delicate balance of heat and evolving ice fabrics. Nevertheless, the bed beneath an ice stream cannot be ignored. It is ultimately the state of the underlying marine sediment that determines whether the ice stream can slide at all. There too, the heat balance is critical with an influx of water required to keep the bed wet enough to let the streams glide along. Ice stream research has been the portal through which glaciologists have seen and identified the complexities of West Antarctic ice sheet dynamics. Remarkably, nearly all time scales seem important. Ice stream

  19. Inventory of miscellaneous streams

    SciTech Connect

    Atencio, B.P.

    1996-09-01

    On December 23, 1991, the U.S. Dep of Energy, Richland Operations Office (DOE-RL) and the Washington State Department of Ecology (Ecology) agreed to adhere to the provisions of the Department of Ecology Consent Order No. DE 9INM-177 (Consent Order) (Ecology and U.S. DOE 1991). The Consent Order lists the regulatory milestones for liquid effluent at the Hanford Site to comply with the permitting requirements of Washington Administrative Code (WAC) 173-216 (State Waste Discharge Permit Program) or WAC 173-218 (Washington Underground Injection Control Progam) where applicable. DOE-RL provided the U.S Congress a plan and schedule to discontinue disposal of contaminated liquid effluent into the soil column on the Hanford Site (DOE 1987). The plan and schedule document contained a strategy for the implementation of alternative treatment and disposal systems. This strategy included prioritizing the into two phases. The Phase I streams were considered to be higher priority than the Phase II streams. The actions recommended for the Phase I and II streams were incorporated in the Hanford Federal Facility A and Consent Order (Tri Party Agreement ) (Ecology, et al. 1994). Miscellaneous Streams are those liquid effluent identified within the Consent Order that are discharged to the ground but are not categorized as Phase I or Phase II Streams. Miscellaneous discharging to the soil column on the Hanford Site are subject to requirements of several milestones identified in the Consent Order. The Plan and Schedule for Disposition and Regulatory Compliance for Miscellaneous Streams (DOE/RL,93-94) provides a plan and schedule for the disposition of Miscellaneous Streams to satisfy one of the Consent Order requirements. One of the commitments (Activity 6-2.2) established in the plan and schedule is to annually update the Miscellaneous Stream Inventory. The annual update will continue until September of 1998, at which time four categorical permit applications are scheduled to have been

  20. Montana StreamStats

    USGS Publications Warehouse

    2016-04-05

    About this volumeMontana StreamStats is a Web-based geographic information system (http://water.usgs.gov/osw/streamstats/) application that provides users with access to basin and streamflow characteristics for gaged and ungaged streams in Montana. Montana StreamStats was developed by the U.S. Geological Survey (USGS) in cooperation with the Montana Departments of Transportation, Environmental Quality, and Natural Resources and Conservation. The USGS Scientific Investigations Report consists of seven independent but complementary chapters dealing with various aspects of this effort.Chapter A describes the Montana StreamStats application, the basin and streamflow datasets, and provides a brief overview of the streamflow characteristics and regression equations used in the study. Chapters B through E document the datasets, methods, and results of analyses to determine streamflow characteristics, such as peak-flow frequencies, low-flow frequencies, and monthly and annual characteristics, for USGS streamflow-gaging stations in and near Montana. The StreamStats analytical toolsets that allow users to delineate drainage basins and solve regression equations to estimate streamflow characteristics at ungaged sites in Montana are described in Chapters F and G.

  1. Students' Experiences of Ability-Based Streaming in Vocational Education

    ERIC Educational Resources Information Center

    Tanggaard, Lene; Nielsen, Klaus; Jørgensen, Christian Helms

    2015-01-01

    Purpose: Since 2007, it has been mandatory for all vocational schools in Denmark to assess the prior qualifications of all students when they begin at the school and to use this assessment to divide students into different ability-based courses (streaming) with the aim of increasing the retention of students. The purpose of this paper is to…

  2. Seasonal nitrate uptake and denitrification potential in small headwater streams in the Willamette Valley, Oregon

    EPA Science Inventory

    Background/Question/Methods Headwater streams can serve as important sources and sinks for nitrogen (N) for downstream receiving waters. Prior research on N removal in small streams has largely focused on growing season conditions. Here we examine the influence of headwater...

  3. SAR observations of the Gulf Stream during SWADE

    NASA Technical Reports Server (NTRS)

    Vachon, Paris W.; Liu, Antony K.; Mollo-Christensen, Erik

    1992-01-01

    The Surface Wave Dynamics Experiment (SWADE) has gathered SAR observations of the Gulf Stream that show a change in ocean surface brightness; this may be due to the effects of a change in air-sea temperature difference across the observed edge, where the boundary is defined by warm, quickly flowing Gulf Stream water and cooler, relatively stationary shelf water. The two images discussed indicate the possibility of deepening understanding of Gulf Stream front dynamics by using the abundant spatial data of SAR imagery, in conjunction with more conventional (point-like) data on hydrography and currents.

  4. Digital Multicasting of Multiple Audio Streams

    NASA Technical Reports Server (NTRS)

    Macha, Mitchell; Bullock, John

    2007-01-01

    The Mission Control Center Voice Over Internet Protocol (MCC VOIP) system (see figure) comprises hardware and software that effect simultaneous, nearly real-time transmission of as many as 14 different audio streams to authorized listeners via the MCC intranet and/or the Internet. The original version of the MCC VOIP system was conceived to enable flight-support personnel located in offices outside a spacecraft mission control center to monitor audio loops within the mission control center. Different versions of the MCC VOIP system could be used for a variety of public and commercial purposes - for example, to enable members of the general public to monitor one or more NASA audio streams through their home computers, to enable air-traffic supervisors to monitor communication between airline pilots and air-traffic controllers in training, and to monitor conferences among brokers in a stock exchange. At the transmitting end, the audio-distribution process begins with feeding the audio signals to analog-to-digital converters. The resulting digital streams are sent through the MCC intranet, using a user datagram protocol (UDP), to a server that converts them to encrypted data packets. The encrypted data packets are then routed to the personal computers of authorized users by use of multicasting techniques. The total data-processing load on the portion of the system upstream of and including the encryption server is the total load imposed by all of the audio streams being encoded, regardless of the number of the listeners or the number of streams being monitored concurrently by the listeners. The personal computer of a user authorized to listen is equipped with special- purpose MCC audio-player software. When the user launches the program, the user is prompted to provide identification and a password. In one of two access- control provisions, the program is hard-coded to validate the user s identity and password against a list maintained on a domain-controller computer

  5. Meandering stream reservoirs

    SciTech Connect

    Richardson, J.G.; Sangree, J.B.; Sneider, R.M.

    1987-12-01

    Braided stream deposits, described in a previous article in this series, and meandering stream deposits commonly are excellent reservoirs. Meandering high-sinuousity channels are found on flat alluvial plains with slopes less than 1 1/2/sup 0/ (0.026 rad). These rivers have wide ranges of discharges from low-water flow to flood stage. Two main processes are responsible for development of sand bodies. These are point-bar deposits left by channel migration, and oxbow-lake deposits left in loops of the river course abandoned when the stream cuts a new course during flooding. Extremely high floods spill over the banks and deposit sheets of very fine sand, silt, and clay onto the flood plain.

  6. Recognition of Prior Vocational Learning in Sweden

    ERIC Educational Resources Information Center

    Andersson, Per; Fejes, Andreas; Ahn, Song-Ee

    2004-01-01

    Initiatives in the recognition of prior learning (RPL) have been taken in Sweden in recent years, mainly focusing on prior vocational learning among immigrants. The government started different projects to find methods for recognising a person's prior learning in the field of vocational competence. This article presents a study of how these…

  7. Prior Learning Assessment Workgroup: 2014 Progress Report

    ERIC Educational Resources Information Center

    West, Jim

    2015-01-01

    Legislation passed in 2011 required the Washington Student Achievement Council (WSAC) to convene a Prior Learning Assessment Workgroup. The workgroup was tasked with coordinating and implementing seven goals, described in statute, to promote the award of college credit for prior learning. Awarding college credit for prior learning increases access…

  8. Assessing Prior Learning--A CAEL Handbook.

    ERIC Educational Resources Information Center

    Knapp, Joan

    A model for assessing and awarding credit for prior experiential learning is presented; the adult student's experiences are summarized in a portfolio. The model incorporates eight stages: facilitating the construction and assessment of a portfolio, identifying significant prior experiences, expressing the learning outcomes of prior experiences,…

  9. 21 CFR 181.5 - Prior sanctions.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... FOOD INGREDIENTS General Provisions § 181.5 Prior sanctions. (a) A prior sanction shall exist only for... food additive or GRAS regulation promulgated after a general evaluation of use of an ingredient... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Prior sanctions. 181.5 Section 181.5 Food...

  10. 21 CFR 181.5 - Prior sanctions.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... CONSUMPTION (CONTINUED) PRIOR-SANCTIONED FOOD INGREDIENTS General Provisions § 181.5 Prior sanctions. (a) A... use of the ingredient, in order to prevent the adulteration of food in violation of section 402 of the... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Prior sanctions. 181.5 Section 181.5 Food...

  11. 21 CFR 181.5 - Prior sanctions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... CONSUMPTION (CONTINUED) PRIOR-SANCTIONED FOOD INGREDIENTS General Provisions § 181.5 Prior sanctions. (a) A... use of the ingredient, in order to prevent the adulteration of food in violation of section 402 of the... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Prior sanctions. 181.5 Section 181.5 Food and...

  12. 21 CFR 181.5 - Prior sanctions.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... CONSUMPTION (CONTINUED) PRIOR-SANCTIONED FOOD INGREDIENTS General Provisions § 181.5 Prior sanctions. (a) A... use of the ingredient, in order to prevent the adulteration of food in violation of section 402 of the... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Prior sanctions. 181.5 Section 181.5 Food...

  13. 21 CFR 181.5 - Prior sanctions.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... CONSUMPTION (CONTINUED) PRIOR-SANCTIONED FOOD INGREDIENTS General Provisions § 181.5 Prior sanctions. (a) A... use of the ingredient, in order to prevent the adulteration of food in violation of section 402 of the... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Prior sanctions. 181.5 Section 181.5 Food...

  14. Stream discharge events increase the reaction efficiency of the hyporheic zone of an in-stream gravel bar

    NASA Astrophysics Data System (ADS)

    Fleckenstein, J. H.; Trauth, N.; Schmidt, C.

    2015-12-01

    Streambed structures such as dunes, pool-riffles or bars enhance the exchange of stream water and solutes with the subsurface, the hyporheic zone. Prior studies have evaluated the factors which control hyporheic exchange and biogeochemical processes for steady state hydrological conditions using numerical models. However, the impact of natural discharge variability on water and solute exchange, creating hydraulically specific conditions for the reactions in the shallow streambed, has not been studied so far. In our study, we set up a transient flow and reactive transport model to elucidate the impact of single stream discharge events on water exchange, solute transport and reactions within the hyporheic zone of an in-stream gravel bar. The discharge events were varied by their duration and the maximum stream discharge. Temporally variable hydraulic heads were assigned as hydraulic head boundary conditions at the top of the reactive groundwater model MIN3P. A steady ambient groundwater flow field was introduced by lateral upstream and downstream hydraulic head boundaries, generating in combination with the stream water level, losing, neutral, or gaining stream conditions. Stream water borne dissolved oxygen, dissolved organic carbon and nitrate can infiltrate into the modelling domain across the top boundary and can react with each other by aerobic respiration and denitrification. Our results show that water and solute exchange through the hyporheic zone (only stream water that infiltrates into the subsurface and exfiltrates back to the stream) is highly dependent on the interplay between event characteristics and the ambient groundwater level. In scenarios where the stream discharge shifts the hydraulic system to strong and long-lasting losing conditions, hyporheic flow paths are longer and the extent of the hyporheic zone are deeper than under base flow conditions and small events where gaining conditions prevail. Consequently, stream discharge events may

  15. Stream temperature response to variable glacier coverage in coastal watersheds of northern southeast Alaska

    NASA Astrophysics Data System (ADS)

    Hood, E. W.; Fellman, J. B.; Nagorski, S. A.; Vermilyea, A.; Pyare, S.; Scott, D.

    2012-12-01

    Glaciers in southeast Alaska are experiencing high rates of ice thinning and retreat. These ongoing changes in glacier volume are altering the proportion of streamflow derived from glacial runoff, which can be an important control on the thermal regime of streams in the region. We measured stream temperature continuously during the 2011 summer runoff season (May through October) in nine watersheds of southeast Alaska that provide spawning habitat for Pacific salmon. Six of the nine watersheds have glacier coverage ranging from 2 to 63%. Our goal was to determine how air temperature and watershed land cover, particularly glacier coverage, influence stream temperature across the seasonal hydrograph. Multiple linear regression identified mean watershed elevation, which is tied to glacier extent, and watershed lake coverage (%) as the strongest landscape controls on mean monthly stream temperature, with the weakest (May) and strongest (July) models explaining 86% and 97% of the temperature variability, respectively. Mean weekly stream temperature was significantly related to mean weekly air temperature in seven of the nine streams; however, the relationships were weak to non-significant in the streams dominated by glacial runoff. Peak summer stream temperatures occurred much earlier in the glacial streams (typically around late May) and glaciers also had a cooling effect on monthly mean stream temperature during the summer (July through September) equivalent to a decrease of 1.1°C for each 10% increase in glacier coverage. Streams with >30% glacier coverage demonstrated decreasing stream temperatures with rising summer air temperatures, while those with <30% glacier coverage exhibited summertime warming. The maximum weekly average temperature (MWAT, an index of thermal suitability for salmon species) in the six glacial streams was substantially below the lower threshold for optimum salmonid growth. This finding suggests that, while glaciers are important for

  16. Measuring and Modeling Stream Temperature in a Forested Ozark Border Stream: An Energy Balance Approach

    NASA Astrophysics Data System (ADS)

    Bulliner, E. A.; Hubbart, J. A.

    2010-12-01

    Forested riparian buffers play an important role in modulating stream water quality, including temperature. Studies are needed to characterize canopy energy attenuation and thus buffering of stream temperature. This is particularly the case in the central hardwood forest regions of the United States where relationships between canopy density and stream temperature in karst terrain is not well understood. Data were collected from two intensively instrumented study sites along two stream reaches of opposing orientation in a semi-karst watershed on the border of southern Missouri’s Ozark region, USA, during the 2010 water year. Data supplied the necessary information to calculate an energy budget for each stream reach. From October 2009- July 2010, total precipitation was 110 cm as measured from a nearby reference flux tower (US DOE). Average estimated stream discharge was 0.20 m3/s in the E-W oriented reach and 0.27 m3/s in the N-S oriented reach. Average air temperature was 9.3 °C along the E-W reach and 10.0 °C along the N-S reach, while measured average incident shortwave radiation was 45.2 W/m2 along the E-W reach and 48.5 W/m2 along the N-S reach. Temporal and spatial variation in the site’s multilayered forest canopy was quantified via ceptometer and hemispherical photography. Average measured leaf area index (LAI) in April-May 2010 (ceptometer) was 1.89 within the riparian zone (n=77) and 1.48 within the canopy gap created by the stream (n=14), while average LAI from June-July was 4.04 within the riparian zone and 2.80 within the gap. Stream water latent and sensible heat exchange with the overlying air was modeled based on hourly averages of microclimate measurements taken along each reach. Average latent heat flux from the stream was -16.7 W/m2 within the E-W reach and -17.6 W/m2 within the N-S reach (negative values indicate energy loss). Average sensible heat flux from the stream was -1.34 W/m2 within the E-W reach and -2.27 W/m2 within the N-S reach

  17. Combustor air flow control method for fuel cell apparatus

    DOEpatents

    Clingerman, Bruce J.; Mowery, Kenneth D.; Ripley, Eugene V.

    2001-01-01

    A method for controlling the heat output of a combustor in a fuel cell apparatus to a fuel processor where the combustor has dual air inlet streams including atmospheric air and fuel cell cathode effluent containing oxygen depleted air. In all operating modes, an enthalpy balance is provided by regulating the quantity of the air flow stream to the combustor to support fuel cell processor heat requirements. A control provides a quick fast forward change in an air valve orifice cross section in response to a calculated predetermined air flow, the molar constituents of the air stream to the combustor, the pressure drop across the air valve, and a look up table of the orifice cross sectional area and valve steps. A feedback loop fine tunes any error between the measured air flow to the combustor and the predetermined air flow.

  18. The power prior: theory and applications.

    PubMed

    Ibrahim, Joseph G; Chen, Ming-Hui; Gwon, Yeongjin; Chen, Fang

    2015-12-10

    The power prior has been widely used in many applications covering a large number of disciplines. The power prior is intended to be an informative prior constructed from historical data. It has been used in clinical trials, genetics, health care, psychology, environmental health, engineering, economics, and business. It has also been applied for a wide variety of models and settings, both in the experimental design and analysis contexts. In this review article, we give an A-to-Z exposition of the power prior and its applications to date. We review its theoretical properties, variations in its formulation, statistical contexts for which it has been used, applications, and its advantages over other informative priors. We review models for which it has been used, including generalized linear models, survival models, and random effects models. Statistical areas where the power prior has been used include model selection, experimental design, hierarchical modeling, and conjugate priors. Frequentist properties of power priors in posterior inference are established, and a simulation study is conducted to further examine the empirical performance of the posterior estimates with power priors. Real data analyses are given illustrating the power prior as well as the use of the power prior in the Bayesian design of clinical trials.

  19. The power prior: theory and applications.

    PubMed

    Ibrahim, Joseph G; Chen, Ming-Hui; Gwon, Yeongjin; Chen, Fang

    2015-12-10

    The power prior has been widely used in many applications covering a large number of disciplines. The power prior is intended to be an informative prior constructed from historical data. It has been used in clinical trials, genetics, health care, psychology, environmental health, engineering, economics, and business. It has also been applied for a wide variety of models and settings, both in the experimental design and analysis contexts. In this review article, we give an A-to-Z exposition of the power prior and its applications to date. We review its theoretical properties, variations in its formulation, statistical contexts for which it has been used, applications, and its advantages over other informative priors. We review models for which it has been used, including generalized linear models, survival models, and random effects models. Statistical areas where the power prior has been used include model selection, experimental design, hierarchical modeling, and conjugate priors. Frequentist properties of power priors in posterior inference are established, and a simulation study is conducted to further examine the empirical performance of the posterior estimates with power priors. Real data analyses are given illustrating the power prior as well as the use of the power prior in the Bayesian design of clinical trials. PMID:26346180

  20. Toward Third Stream Evaluation.

    ERIC Educational Resources Information Center

    Della-Piana, Gabriel M.; Endo, George T.

    Third stream evaluation, the fusing of the ecological perspective with experimental or quasi-experimental evaluation design, is described. The ecological perspective necessitates that the conceptualization and analysis of a setting and the design of the study emphasize the interdependent relations among organisms, behavior and environment in…

  1. Two Phase Streaming Potentials

    SciTech Connect

    Marsden, S S; Wheatall, M W

    1987-01-20

    The streaming potentials generated by the flow of both liquid and gas through either a Pyrex capillary tube or else an unconsolidated Pyrex porous medium were investigated. This mixture of distilled water plus nitrogen gas simulated wet stream but allowed experiments to be run at room temperature. Single-phase flow of distilled water alone resulted in a constant voltage-to-pressure drop ratio, E/Δp, of +0.15 v/psi for the capillary tube and -0.52 v/psi for the porous medium. For both single- and two-phase flow through the capillary tube, the upstream potential was always positive relative to the downstream electrode while the opposite was true for the porous medium. The maximum two-phase potentials generated in the porous medium were about four times as great as those generated in the capillary tube for similar gas fractions, Γ. For the capillary tube experiments the potentials generated when Γ < ≈ 0.5 were equal to or slightly less than those for single-phase flow, while for the porous medium the potentials were always greater than those for single-phase flow. When Γ > ≈ 0.5 for both kinds of flow systems Γ had a profound effect on streaming potential and reached a pronounced maximum when 0.94 < Γ < 0.99. The implications of these streaming potentials for geothermal exploration and delineation of geothermal reservoirs is also discussed in the paper. 7 figs., 10 refs.

  2. Practical Meteor Stream Forecasting

    NASA Technical Reports Server (NTRS)

    Cooke, William J.; Suggs, Robert M.

    2003-01-01

    Inspired by the recent Leonid meteor storms, researchers have made great strides in our ability to predict enhanced meteor activity. However, the necessary calibration of the meteor stream models with Earth-based ZHRs (Zenith Hourly Rates) has placed emphasis on the terran observer and meteor activity predictions are published in such a manner to reflect this emphasis. As a consequence, many predictions are often unusable by the satellite community, which has the most at stake and the greatest interest in meteor forecasting. This paper suggests that stream modelers need to pay more attention to the needs of this community and publish not just durations and times of maxima for Earth, but everything needed to characterize the meteor stream in and out of the plane of the ecliptic, which, at a minimum, consists of the location of maximum stream density (ZHR) and the functional form of the density decay with distance from this point. It is also suggested that some of the terminology associated with meteor showers may need to be more strictly defined in order to eliminate the perception of crying wolf by meteor scientists. An outburst is especially problematic, as it usually denotes an enhancement by a factor of 2 or more to researchers, but conveys the notion of a sky filled with meteors to satellite operators and the public. Experience has also taught that predicted ZHRs often lead to public disappointment, as these values vastly overestimate what is seen.

  3. IDENTIFYING STAR STREAMS IN THE MILKY WAY HALO

    SciTech Connect

    King, Charles III; Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J. E-mail: wbrown@cfa.harvard.edu E-mail: skenyon@cfa.harvard.edu

    2012-05-01

    We develop statistical methods for identifying star streams in the halo of the Milky Way that exploit observed spatial and radial velocity distributions. Within a great circle, departures of the observed spatial distribution from random provide a measure of the likelihood of a potential star stream. Comparisons between the radial velocity distribution within a great circle and the radial velocity distribution of the entire sample also measure the statistical significance of potential streams. The radial velocities enable construction of a more powerful joint statistical test for identifying star streams in the Milky Way halo. Applying our method to halo stars in the Hypervelocity Star (HVS) survey, we detect the Sagittarius stream at high significance. Great circle counts and comparisons with theoretical models suggest that the Sagittarius stream comprises 10%-17% of the halo stars in the HVS sample. The population of blue stragglers and blue horizontal branch stars varies along the stream and is a potential probe of the distribution of stellar populations in the Sagittarius dwarf galaxy prior to disruption.

  4. Dam removal increases American eel abundance in distant headwater streams

    USGS Publications Warehouse

    Hitt, Nathaniel P.; Eyler, Sheila; Wofford, John E.B.

    2012-01-01

    American eel Anguilla rostrata abundances have undergone significant declines over the last 50 years, and migration barriers have been recognized as a contributing cause. We evaluated eel abundances in headwater streams of Shenandoah National Park, Virginia, to compare sites before and after the removal of a large downstream dam in 2004 (Embrey Dam, Rappahannock River). Eel abundances in headwater streams increased significantly after the removal of Embrey Dam. Observed eel abundances after dam removal exceeded predictions derived from autoregressive models parameterized with data prior to dam removal. Mann–Kendall analyses also revealed consistent increases in eel abundances from 2004 to 2010 but inconsistent temporal trends before dam removal. Increasing eel numbers could not be attributed to changes in local physical habitat (i.e., mean stream depth or substrate size) or regional population dynamics (i.e., abundances in Maryland streams or Virginia estuaries). Dam removal was associated with decreasing minimum eel lengths in headwater streams, suggesting that the dam previously impeded migration of many small-bodied individuals (<300 mm TL). We hypothesize that restoring connectivity to headwater streams could increase eel population growth rates by increasing female eel numbers and fecundity. This study demonstrated that dams may influence eel abundances in headwater streams up to 150 river kilometers distant, and that dam removal may provide benefits for eel management and conservation at the landscape scale.

  5. Air heating system

    DOEpatents

    Primeau, John J.

    1983-03-01

    A self-starting, fuel-fired, air heating system including a vapor generator, a turbine, and a condenser connected in a closed circuit such that the vapor output from the vapor generator is conducted to the turbine and then to the condenser where it is condensed for return to the vapor generator. The turbine drives an air blower which passes air over the condenser for cooling the condenser. Also, a condensate pump is driven by the turbine. The disclosure is particularly concerned with the provision of heat exchanger and circuitry for cooling the condensed fluid output from the pump prior to its return to the vapor generator.

  6. Deployable Engine Air Brake

    NASA Technical Reports Server (NTRS)

    2014-01-01

    On approach, next-generation aircraft are likely to have airframe noise levels that are comparable to or in excess of engine noise. ATA Engineering, Inc. (ATA) is developing a novel quiet engine air brake (EAB), a device that generates "equivalent drag" within the engine through stream thrust reduction by creating a swirling outflow in the turbofan exhaust nozzle. Two Phase II projects were conducted to mature this technology: (1) a concept development program (CDP) and (2) a system development program (SDP).

  7. A Simulated Stream Ecology Study.

    ERIC Educational Resources Information Center

    Zampella, Robert A.

    1979-01-01

    Describes a simulated field experience to study stream ecology in the classroom. Secondary students determine the composition of the stream community, describe the distribution of the benthic invertebrates, and design a food web. (Author/MA)

  8. Stream discharge events increase the reactive efficiency of the hyporheic zone of an in-stream gravel bar

    NASA Astrophysics Data System (ADS)

    Trauth, Nico; Schmidt, Christian; Fleckenstein, Jan H.

    2016-04-01

    Streambed structures such as dunes, pool-riffles or bars enhance the exchange of stream water and solutes with the subsurface, the hyporheic zone. Prior studies have evaluated the factors which control hyporheic exchange and biogeochemical processes for steady state hydrological conditions using numerical models. However, the impact of natural discharge variability on water and solute exchange, creating hydraulically specific conditions for the reactions in the shallow streambed, has received less attention to date. In our study, we set up a transient flow and reactive transport model to elucidate the impact of single stream discharge events on water exchange, solute transport and reactions within the hyporheic zone of an in-stream gravel bar. The discharge events were varied by their duration and the maximum stream discharge. Temporally varying hydraulic heads were assigned as hydraulic head boundary conditions at the top of the reactive groundwater model MIN3P. A steady ambient groundwater flow field was introduced by lateral upstream and downstream hydraulic head boundaries, resulting in losing, neutral, or gaining conditions in the stream with respect to exchange with groundwater. Stream water borne dissolved oxygen, dissolved organic carbon and nitrate can infiltrate across the top of the modelling domain, where aerobic respiration and denitrification are simulated. Our results show that water and solute exchange through the hyporheic zone (only stream water that infiltrates into the subsurface and exfiltrates back to the stream) is highly dependent on the interplay between event characteristics and the ambient groundwater level. In scenarios where the stream discharge shifts the hydraulic system to strong and long-lasting losing conditions, hyporheic flow paths are longer and the extent of the hyporheic zone deeper than under base flow conditions and small hydrologic events where gaining conditions prevail. Consequently, stream discharge events may

  9. 40 CFR 91.309 - Engine intake air temperature measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Engine intake air temperature... Provisions § 91.309 Engine intake air temperature measurement. (a) Engine intake air temperature measurement... the supply system or in the air stream entering the engine. (b) The temperature measurements must...

  10. 40 CFR 91.309 - Engine intake air temperature measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Engine intake air temperature... Provisions § 91.309 Engine intake air temperature measurement. (a) Engine intake air temperature measurement... the supply system or in the air stream entering the engine. (b) The temperature measurements must...

  11. 40 CFR 91.309 - Engine intake air temperature measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Engine intake air temperature... Provisions § 91.309 Engine intake air temperature measurement. (a) Engine intake air temperature measurement... the supply system or in the air stream entering the engine. (b) The temperature measurements must...

  12. 40 CFR 91.309 - Engine intake air temperature measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Engine intake air temperature... Provisions § 91.309 Engine intake air temperature measurement. (a) Engine intake air temperature measurement... the supply system or in the air stream entering the engine. (b) The temperature measurements must...

  13. 40 CFR 91.309 - Engine intake air temperature measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Engine intake air temperature... Provisions § 91.309 Engine intake air temperature measurement. (a) Engine intake air temperature measurement... the supply system or in the air stream entering the engine. (b) The temperature measurements must...

  14. Studying snails and stream health

    SciTech Connect

    Krause, C.

    1992-01-01

    A type of snail (Elimia) that is abundant in most streams in east Tennessee is noticeably absent in contaminated Oak Ridge streams, indicating a significant level of pollution. Such a snail could serve as a sensitive indicator of and contributor to improved water quality in Oak Ridge streams as remediation programs take effect.

  15. Influence of a Waterfall on Summer Stream Temperature

    NASA Astrophysics Data System (ADS)

    Moore, R. D.

    2015-12-01

    Summer stream temperature generally increases from the headwaters down to the outlets of major rivers, with longitudinal thermal gradients modified by riparian forest cover, groundwater and tributary inflows, the presence of surface water bodies, and potentially other landscape features. The objective of this study was to document downstream changes in summer stream temperature associated with a waterfall. The study focused on Shannon Falls in south coastal British Columbia, which descends 350 m over a horizontal distance of 500 m. Flow is cascading and highly aerated for most of its descent. Stream temperature was recorded at 10-minute intervals above and below the falls, and discharge was recorded 200 m downstream of the falls. Hourly air temperature, relative humidity and wind speed were recorded at Squamish Airport, 12 km from the falls; air temperature and humidity were also recorded upstream of the falls at streamside and at an open site 100 m from the stream. The stream warmed 1 to 4 °C during its descent, with diurnal variations of about 1 °C during fine weather. A full energy balance analysis is not possible due to an inability to quantify the stream's surface area and its complex radiation geometry. Calculations indicate that the conversion of potential energy accounts for 0.8 °C of warming. An index of the combined effects of sensible and latent heat flux explained 70% of the variance in the downstream temperature changes, consistent with the hypothesis that the turbulent exchanges are enhanced in cascading, aerated flow.

  16. Autonomous Byte Stream Randomizer

    NASA Technical Reports Server (NTRS)

    Paloulian, George K.; Woo, Simon S.; Chow, Edward T.

    2013-01-01

    Net-centric networking environments are often faced with limited resources and must utilize bandwidth as efficiently as possible. In networking environments that span wide areas, the data transmission has to be efficient without any redundant or exuberant metadata. The Autonomous Byte Stream Randomizer software provides an extra level of security on top of existing data encryption methods. Randomizing the data s byte stream adds an extra layer to existing data protection methods, thus making it harder for an attacker to decrypt protected data. Based on a generated crypto-graphically secure random seed, a random sequence of numbers is used to intelligently and efficiently swap the organization of bytes in data using the unbiased and memory-efficient in-place Fisher-Yates shuffle method. Swapping bytes and reorganizing the crucial structure of the byte data renders the data file unreadable and leaves the data in a deconstructed state. This deconstruction adds an extra level of security requiring the byte stream to be reconstructed with the random seed in order to be readable. Once the data byte stream has been randomized, the software enables the data to be distributed to N nodes in an environment. Each piece of the data in randomized and distributed form is a separate entity unreadable on its own right, but when combined with all N pieces, is able to be reconstructed back to one. Reconstruction requires possession of the key used for randomizing the bytes, leading to the generation of the same cryptographically secure random sequence of numbers used to randomize the data. This software is a cornerstone capability possessing the ability to generate the same cryptographically secure sequence on different machines and time intervals, thus allowing this software to be used more heavily in net-centric environments where data transfer bandwidth is limited.

  17. Multi-stream inflation

    SciTech Connect

    Li, Miao; Wang, Yi E-mail: wangyi@itp.ac.cn

    2009-07-01

    We propose a ''multi-stream'' inflation model, which is a double field model with spontaneous breaking and restoration of an approximate symmetry. We calculate the density perturbation and non-Gaussianity in this model. We find that this model can have large, scale dependent, and probably oscillating non-Gaussianity. We also note that our model can produce features in the CMB power spectrum and hemispherical power asymmetry.

  18. Comparison of drinking water treatment process streams for optimal bacteriological water quality.

    PubMed

    Ho, Lionel; Braun, Kalan; Fabris, Rolando; Hoefel, Daniel; Morran, Jim; Monis, Paul; Drikas, Mary

    2012-08-01

    Four pilot-scale treatment process streams (Stream 1 - Conventional treatment (coagulation/flocculation/dual media filtration); Stream 2 - Magnetic ion exchange (MIEX)/Conventional treatment; Stream 3 - MIEX/Conventional treatment/granular activated carbon (GAC) filtration; Stream 4 - Microfiltration/nanofiltration) were commissioned to compare their effectiveness in producing high quality potable water prior to disinfection. Despite receiving highly variable source water quality throughout the investigation, each stream consistently reduced colour and turbidity to below Australian Drinking Water Guideline levels, with the exception of Stream 1 which was difficult to manage due to the reactive nature of coagulation control. Of particular interest was the bacteriological quality of the treated waters where flow cytometry was shown to be the superior monitoring tool in comparison to the traditional heterotrophic plate count method. Based on removal of total and active bacteria, the treatment process streams were ranked in the order: Stream 4 (average log removal of 2.7) > Stream 2 (average log removal of 2.3) > Stream 3 (average log removal of 1.5) > Stream 1 (average log removal of 1.0). The lower removals in Stream 3 were attributed to bacteria detaching from the GAC filter. Bacterial community analysis revealed that the treatments affected the bacteria present, with the communities in streams incorporating conventional treatment clustering with each other, while the community composition of Stream 4 was very different to those of Streams 1, 2 and 3. MIEX treatment was shown to enhance removal of bacteria due to more efficient flocculation which was validated through the novel application of the photometric dispersion analyser.

  19. Gas stream cleanup

    SciTech Connect

    Bossart, S.J.; Cicero, D.C.; Zeh, C.M.; Bedick, R.C.

    1990-08-01

    This report describes the current status and recent accomplishments of gas stream cleanup (GSCU) projects sponsored by the Morgantown Energy Technology Center (METC) of the US Department of Energy (DOE). The primary goal of the Gas Stream Cleanup Program is to develop contaminant control strategies that meet environmental regulations and protect equipment in advanced coal conversion systems. Contaminant control systems are being developed for integration into seven advanced coal conversion processes: Pressurized fludized-bed combustion (PFBC), Direct coal-fueled turbine (DCFT), Intergrated gasification combined-cycle (IGCC), Gasification/molten carbonate fuel cell (MCFC), Gasification/solid oxide fuel cell (SOFC), Coal-fueled diesel (CFD), and Mild gasification (MG). These advanced coal conversion systems present a significant challenge for development of contaminant control systems because they generate multi-contaminant gas streams at high-pressures and high temperatures. Each of the seven advanced coal conversion systems incorporates distinct contaminant control strategies because each has different contaminant tolerance limits and operating conditions. 59 refs., 17 figs., 5 tabs.

  20. The LHCb Turbo stream

    NASA Astrophysics Data System (ADS)

    Puig, A.

    2016-07-01

    The LHCb experiment will record an unprecedented dataset of beauty and charm hadron decays during Run II of the LHC, set to take place between 2015 and 2018. A key computing challenge is to store and process this data, which limits the maximum output rate of the LHCb trigger. So far, LHCb has written out a few kHz of events containing the full raw sub-detector data, which are passed through a full offline event reconstruction before being considered for physics analysis. Charm physics in particular is limited by trigger output rate constraints. A new streaming strategy includes the possibility to perform the physics analysis with candidates reconstructed in the trigger, thus bypassing the offline reconstruction. In the Turbo stream the trigger will write out a compact summary of physics objects containing all information necessary for analyses. This will allow an increased output rate and thus higher average efficiencies and smaller selection biases. This idea will be commissioned and developed during 2015 with a selection of physics analyses. It is anticipated that the turbo stream will be adopted by an increasing number of analyses during the remainder of LHC Run II (2015-2018) and ultimately in Run III (starting in 2020) with the upgraded LHCb detector.

  1. Air Pollution

    MedlinePlus

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, ... Ozone, a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  2. Stream processing health card application.

    PubMed

    Polat, Seda; Gündem, Taflan Imre

    2012-10-01

    In this paper, we propose a data stream management system embedded to a smart card for handling and storing user specific summaries of streaming data coming from medical sensor measurements and/or other medical measurements. The data stream management system that we propose for a health card can handle the stream data rates of commonly known medical devices and sensors. It incorporates a type of context awareness feature that acts according to user specific information. The proposed system is cheap and provides security for private data by enhancing the capabilities of smart health cards. The stream data management system is tested on a real smart card using both synthetic and real data.

  3. A direct approach for quantifying stream shading

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Excessive stream water temperature causes thermal stress in fish and invertebrates, decreases dissolved oxygen, and encourages bacterial and algal growth. Solar radiation affects stream temperature. Shade cast by riparian vegetation reduces thermal inputs to stream water. Stream shading standards...

  4. West Virginia trout streams: target for acid precipitation

    SciTech Connect

    Gasper, D.C.

    1983-01-01

    West Virginia is greatly effected by the Ohio River Valley sources of sulfur because of the westerly winds. Estimates indicate that before 1930 the pH of precipitation was above 5.3, but now the average pH is 4.2. The effects of pollution on trout streams are discussed from two points of view. First, the streams have little ability to neutralize acid from any source, and they are very near (or below) the threshold of a trout's acid tolerance. Secondly, since stream nutrient levels are largely a product of drainage, the hypothesis is presented that if the air is cleaned up the trout streams will be lost. The increased acid activity is leaching from the soil the nutrients that are necessary to maintain the trout populations. Acid shock events are discussed in relation to water quality by acid rain. Present levels of acidity in precipitation threatens over 1/4 of West Virginia trout water with extinction.

  5. Low NOx combustion using cogenerated oxygen and nitrogen streams

    DOEpatents

    Kobayashi, Hisashi; Bool, Lawrence E.; Snyder, William J.

    2009-02-03

    Combustion of hydrocarbon fuel is achieved with less formation of NOx by feeding the fuel into a slightly oxygen-enriched atmosphere, and separating air into oxygen-rich and nitrogen-rich streams which are fed separately into the combustion device.

  6. Investigation of acoustic streaming patterns around oscillating sharp edges

    PubMed Central

    Nama, Nitesh; Huang, Po-Hsun; Huang, Tony Jun; Costanzo, Francesco

    2014-01-01

    Oscillating sharp edges have been employed to achieve rapid and homogeneous mixing in microchannels using acoustic streaming. Here we use a perturbation approach to study the flow around oscillating sharp edges in a microchannel. This work extends prior experimental studies to numerically characterize the effect of various parameters on the acoustically induced flow. Our numerical results match well with the experimental results. We investigated multiple device parameters such as the tip angle, oscillation amplitude, and channel dimensions. Our results indicate that, due to the inherent nonlinearity of acoustic streaming, the channel dimensions could significantly impact the flow patterns and device performance. PMID:24903475

  7. Improving Open Access through Prior Learning Assessment

    ERIC Educational Resources Information Center

    Yin, Shuangxu; Kawachi, Paul

    2013-01-01

    This paper explores and presents new data on how to improve open access in distance education through using prior learning assessments. Broadly there are three types of prior learning assessment (PLAR): Type-1 for prospective students to be allowed to register for a course; Type-2 for current students to avoid duplicating work-load to gain…

  8. Prior Computer Experience and Technology Acceptance

    ERIC Educational Resources Information Center

    Varma, Sonali

    2010-01-01

    Prior computer experience with information technology has been identified as a key variable (Lee, Kozar, & Larsen, 2003) that can influence an individual's future use of newer computer technology. The lack of a theory driven approach to measuring prior experience has however led to conceptually different factors being used interchangeably in…

  9. 28 CFR 2.58 - Prior orders.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Prior orders. 2.58 Section 2.58 Judicial Administration DEPARTMENT OF JUSTICE PAROLE, RELEASE, SUPERVISION AND RECOMMITMENT OF PRISONERS, YOUTH OFFENDERS, AND JUVENILE DELINQUENTS United States Code Prisoners and Parolees § 2.58 Prior orders. Any order...

  10. On selecting a prior for the precision parameter of Dirichlet process mixture models

    USGS Publications Warehouse

    Dorazio, R.M.

    2009-01-01

    In hierarchical mixture models the Dirichlet process is used to specify latent patterns of heterogeneity, particularly when the distribution of latent parameters is thought to be clustered (multimodal). The parameters of a Dirichlet process include a precision parameter ?? and a base probability measure G0. In problems where ?? is unknown and must be estimated, inferences about the level of clustering can be sensitive to the choice of prior assumed for ??. In this paper an approach is developed for computing a prior for the precision parameter ?? that can be used in the presence or absence of prior information about the level of clustering. This approach is illustrated in an analysis of counts of stream fishes. The results of this fully Bayesian analysis are compared with an empirical Bayes analysis of the same data and with a Bayesian analysis based on an alternative commonly used prior.

  11. Afforestation and stream temperature in a temperate maritime environment

    NASA Astrophysics Data System (ADS)

    Webb, B. W.; Crisp, D. T.

    2006-01-01

    There have been few long term investigations of the effects of afforestation on stream temperatures in the UK, and the present study uses the results of continuous monitoring of water temperatures in a forest and a moorland stream of the Loch Grannoch area in southwest Scotland over a 4 year period to investigate the effects of planting coniferous forest on stream thermal regime. The presence of a coniferous tree canopy resulted in a lowering of mean water temperatures by 0.5 °C but larger reductions in summer monthly mean maxima and diel ranges of up to 5 °C and 4 °C respectively. The diel cycle in the forested stream lagged behind that of the moorland site in all months of the year, but the delay in timing was greater for the peak than for the trough in the diel cycle. Mean water temperatures were higher in the forest stream during the mid-winter months, reflecting higher minimum values. Contrasts in stream thermal regime between forest and moorland showed relatively little interannual variability over the study period. Continuous monitoring of air temperatures during 2002 revealed contrasts between the study sites that were less pronounced for air than for water temperature, and suggested it is the shading of incoming solar radiation that has a strong effect in determining the water temperature behaviour of the forested stream. Although the biological impact of the observed contrasts in stream temperature between land uses is likely to be relatively modest, the presence of forest cover moderates the occurrence of high summer temperatures inimical to the survival of some salmonid species.

  12. Synthesis cathode material LiNi0.80Co0.15Al0.05O2 with two step solid-state method under air stream

    NASA Astrophysics Data System (ADS)

    Xia, Shubiao; Zhang, Yingjie; Dong, Peng; Zhang, Yannan

    2014-01-01

    A facile generic strategy of solid-state reaction under air atmosphere is employed to prepare LiNi0.8Co0.15Al0.05O2 layer structure micro-sphere as cathodes for Li-ion batteries. The impurity phase has been eliminated wholly without changing the R-3m space group of LiNi0.8Co0.15Al0.05O2. The electrochemical performance of LiNi0.8Co0.15Al0.05O2 cathodes depend on the sintering step, temperature, particle size and uniformity. The sample pre-sintered at 540 °C for 12 h and then sintered at 720 °C for 28 h exhibits the best electrochemical performance, which delivers a reversible capacity of 180.4, 165.8, 154.7 and 135.6 mAhg-1 at 0.2 C, 1 C, 2 C and 5 C, respectively. The capacity retention keeps over 87% after 76 cycles at 1 C. This method is simple, cheap and mass-productive, and thus suitable to large scale production of NCA cathodes directly used for lithium ion batteries.

  13. Riparian shading and groundwater enhance growth potential for smallmouth bass in Ozark streams.

    PubMed

    Whitledge, Gregory W; Rabeni, Charles F; Annis, Gust; Sowa, Scott P

    2006-08-01

    Moderation of stream temperatures by riparian shading and groundwater are known to promote growth and survival of salmonid fishes, but effects of riparian shade and groundwater on to be growth of warmwater stream fishes are poorly understood or assumed to be negligible. We used stream temperature models to relate shading from riparian vegetation and groundwater inflow to summer water temperatures in Missouri Ozark streams and evaluated effects of summer water temperatures on smallmouth bass, Micropterus dolomieu, growth using a bioenergetics model. Bioenergetics model simulations revealed that adult smallmouth bass in non-spring-fed streams have lower growth potential during summer than fish in spring-fed streams, are subject to mass loss when stream temperatures exceed 27 degrees C, and will likely exhibit greater interannual variation in growth during summer if all growth-influencing factors, other than temperature, are identical between the two stream types. Temperature models indicated that increased riparian shading will expand the longitudinal extent of thermal habitat capable of supporting adult smallmouth bass growth in spring-fed stream reaches when mean daily air temperatures exceed 27 degrees C. Optimum growth temperature (22 degrees C) will be present only in spring-fed streams under these conditions. Potential for increasing shade through riparian restoration is greatest for streams <5 m wide and along north-south reaches of larger streams. However, temperature models also indicated that restoring riparian shading to maximum levels throughout a watershed would increase the total stream mileage capable of supporting positive growth of adult smallmouth bass by only 1-6% when air temperatures are at or near average summer maxima; increases in suitable thermal habitat would be greatest in watersheds with higher spring densities. Riparian management for maintenance or restoration of the thermal habitat of adult smallmouth bass during summer should be

  14. Determination of stream reaeration coefficients by use of tracers

    USGS Publications Warehouse

    Kilpatrick, F.A.; Rathbun, R.E.; Yotsukura, Nobuhiro; Parker, G.W.; DeLong, L.L.

    1989-01-01

    Stream reaeration is the physical absorption of oxygen from the atmosphere by a flowing stream. This is the primary process by which a stream replenishes the oxygen consumed in the biodegradation of organic wastes. Prior to 1965, reaeration rate coefficients could be estimated only by indirect methods. In 1965, a direct method of measuring stream reaeration coefficients was developed whereby a radioactive tracer gas was injected into a stream-the principle being that the tracer gas would be desorbed from the stream inversely to how oxygen would be absorbed. The technique has since been modified by substituting hydrocarbon gases for the radioactive tracer gas. This manual describes the slug-injection and constant-rate-injection methods of measuring gas-tracer desorption. Emphasis is on the use of rhodamine WT dye as a relatively conservative tracer and propane as the nonconservative gas tracer, on planning field tests, on methods of injection, sampling, and analysis, and on techniques for computing desorption and reaeration coefficients.

  15. Informative prior distributions for ELISA analyses.

    PubMed

    Klauenberg, Katy; Walzel, Monika; Ebert, Bernd; Elster, Clemens

    2015-07-01

    Immunoassays are capable of measuring very small concentrations of substances in solutions and have an immense range of application. Enzyme-linked immunosorbent assay (ELISA) tests in particular can detect the presence of an infection, of drugs, or hormones (as in the home pregnancy test). Inference of an unknown concentration via ELISA usually involves a non-linear heteroscedastic regression and subsequent prediction, which can be carried out in a Bayesian framework. For such a Bayesian inference, we are developing informative prior distributions based on extensive historical ELISA tests as well as theoretical considerations. One consideration regards the quality of the immunoassay leading to two practical requirements for the applicability of the priors. Simulations show that the additional prior information can lead to inferences which are robust to reasonable perturbations of the model and changes in the design of the data. On real data, the applicability is demonstrated across different laboratories, for different analytes and laboratory equipment as well as for previous and current ELISAs with sigmoid regression function. Consistency checks on real data (similar to cross-validation) underpin the adequacy of the suggested priors. Altogether, the new priors may improve concentration estimation for ELISAs that fulfill certain design conditions, by extending the range of the analyses, decreasing the uncertainty, or giving more robust estimates. Future use of these priors is straightforward because explicit, closed-form expressions are provided. This work encourages development and application of informative, yet general, prior distributions for other types of immunoassays.

  16. The Phoenix stream: A cold stream in the southern hemisphere

    DOE PAGES

    Balbinot, E.

    2016-03-17

    In this study, we report the discovery of a stellar stream in the Dark Energy Survey (DES) Year 1 (Y1A1) data. The discovery was made through simple color-magnitude filters and visual inspection of the Y1A1 data. We refer to this new object as the Phoenix stream, after its resident constellation. After subtraction of the background stellar population we detect a clear signal of a simple stellar population. By fitting the ridge line of the stream in color-magnitude space, we find that a stellar population with agemore » $$\\tau=11.5\\pm0.5$$ Gyr and $[Fe/H]<-1.6$ located 17.5$$\\pm$$0.9 kpc from the Sun gives an adequate description of the stream stellar population. The stream is detected over an extension of 8$$^{\\circ}.$$1 (2.5 kpc) and has a width of $$\\sim$$54 pc assuming a Gaussian profile, indicating that a globular cluster is a probable progenitor. There is no known globular cluster within 5 kpc compatible with being the progenitor of the stream, assuming that the stream traces its orbit. We examined overdensities along the stream, however no obvious counterpart bound stellar system is visible in the coadded images. We also find overdensities along the stream that appear to be symmetrically distributed - consistent with the epicyclic overdensity scenario for the formation of cold streams - as well as a misalignment between the Northern and Southern part of stream. Despite the close proximity we find no evidence that this stream and the halo cluster NGC 1261 have a common accretion origin linked to the recently found EriPhe overdensity (Li et al. 2016).« less

  17. Riparian deforestation, stream narrowing, and loss of stream ecosystem services

    PubMed Central

    Sweeney, Bernard W.; Bott, Thomas L.; Jackson, John K.; Kaplan, Louis A.; Newbold, J. Denis; Standley, Laurel J.; Hession, W. Cully; Horwitz, Richard J.

    2004-01-01

    A study of 16 streams in eastern North America shows that riparian deforestation causes channel narrowing, which reduces the total amount of stream habitat and ecosystem per unit channel length and compromises in-stream processing of pollutants. Wide forest reaches had more macroinvertebrates, total ecosystem processing of organic matter, and nitrogen uptake per unit channel length than contiguous narrow deforested reaches. Stream narrowing nullified any potential advantages of deforestation regarding abundance of fish, quality of dissolved organic matter, and pesticide degradation. These findings show that forested stream channels have a wider and more natural configuration, which significantly affects the total in-stream amount and activity of the ecosystem, including the processing of pollutants. The results reinforce both current policy of the United States that endorses riparian forest buffers as best management practice and federal and state programs that subsidize riparian reforestation for stream restoration and water quality. Not only do forest buffers prevent nonpoint source pollutants from entering small streams, they also enhance the in-stream processing of both nonpoint and point source pollutants, thereby reducing their impact on downstream rivers and estuaries. PMID:15381768

  18. A basin-scale approach to estimating stream temperatures of tributaries to the lower Klamath River, California.

    PubMed

    Flint, Lorraine E; Flint, Alan L

    2008-01-01

    Stream temperature is an important component of salmonid habitat and is often above levels suitable for fish survival in the Lower Klamath River in northern California. The objective of this study was to provide boundary conditions for models that are assessing stream temperature on the main stem for the purpose of developing strategies to manage stream conditions using Total Maximum Daily Loads. For model input, hourly stream temperatures for 36 tributaries were estimated for 1 Jan. 2001 through 31 Oct. 2004. A basin-scale approach incorporating spatially distributed energy balance data was used to estimate the stream temperatures with measured air temperature and relative humidity data and simulated solar radiation, including topographic shading and corrections for cloudiness. Regression models were developed on the basis of available stream temperature data to predict temperatures for unmeasured periods of time and for unmeasured streams. The most significant factor in matching measured minimum and maximum stream temperatures was the seasonality of the estimate. Adding minimum and maximum air temperature to the regression model improved the estimate, and air temperature data over the region are available and easily distributed spatially. The addition of simulated solar radiation and vapor saturation deficit to the regression model significantly improved predictions of maximum stream temperature but was not required to predict minimum stream temperature. The average SE in estimated maximum daily stream temperature for the individual basins was 0.9 +/- 0.6 degrees C at the 95% confidence interval.

  19. A Simulation of Pell Grant Awards and Costs Using Prior-Prior Year Financial Data

    ERIC Educational Resources Information Center

    Kelchen, Robert; Jones, Gigi

    2015-01-01

    We examine the likely implications of switching from a prior year (PY) financial aid system, the current practice in which students file the Free Application for Federal Student Aid (FAFSA) using income data from the previous tax year, to prior-prior year (PPY), in which data from two years before enrollment is used. While PPY allows students to…

  20. The Southeast Stream Quality Assessment

    USGS Publications Warehouse

    Van Metre, Peter C.; Journey, Celeste A.

    2014-01-01

    In 2014, the U.S. Geological Survey (USGS) National Water-Quality Assessment Program (NAWQA) is assessing stream quality across the Piedmont and southern Appalachian Mountains in the southeastern United States. The goal of the Southeast Stream Quality Assessment (SESQA) is to characterize multiple water-quality factors that are stressors to aquatic life—contaminants, nutrients, sediment, and streamflow alteration—and the relation of these stressors to ecological conditions in streams throughout the region. Findings will provide communities and policymakers with information on which human and environmental factors are the most critical in controlling stream quality and, thus, provide insights about possible approaches to protect or improve stream quality. The SESQA study will be the second regional study by the NAWQA program, and it will be of similar design and scope as the Midwest Stream Quality Assessment conducted in 2013 (Van Metre and others, 2012).

  1. Tidal Streams Near and Far

    NASA Astrophysics Data System (ADS)

    Fardal, Mark A.

    2014-06-01

    The Pandas survey of stars in M31's disk and halo is crisscrossed by numerous tidal features from both M31 and the Milky Way. Here I focus on two narrow stellar streams visible in the survey. They have comparable angular extent in the survey (10-13 degrees long versus only 0.3 degree wide), but one is a local Milky Way stream at about 30 kpc and one is in M31, roughly 25 times more distant. I estimate the stellar mass and metallicity in the streams and the distance gradient along them. The kinematics of the M31 stream is sparsely sampled by red giant stars and globular clusters. Bayesian modeling of the stream data yields accurate constraints on the orbital parameters of the streams.

  2. Stream Lifetimes Against Planetary Encounters

    NASA Technical Reports Server (NTRS)

    Valsecchi, G. B.; Lega, E.; Froeschle, Cl.

    2011-01-01

    We study, both analytically and numerically, the perturbation induced by an encounter with a planet on a meteoroid stream. Our analytical tool is the extension of pik s theory of close encounters, that we apply to streams described by geocentric variables. The resulting formulae are used to compute the rate at which a stream is dispersed by planetary encounters into the sporadic background. We have verified the accuracy of the analytical model using a numerical test.

  3. Waste streams in a typical crewed space habitat: An update

    NASA Technical Reports Server (NTRS)

    Golub, M. A.; Wydeven, T.

    1992-01-01

    A compilation of generation rates and chemical compositions of potential waste streams in a typical crewed space habitat, reported in a prior NASA Technical Memorandum and a related journal article, was updated. This report augments that compilation by the inclusion of the following new data: those data uncovered since completion of the prior report; those obtained from Soviet literature relevant to life support issues; and those for various minor human body wastes not presented previously (saliva, flatus, hair, finger- and toenails, dried skin and skin secretions, tears, and semen), but included here for purposes of completeness. These waste streams complement those discussed previously: toilet waste (urine, feces, etc.), hygiene water (laundry, shower/handwash, dishwasher water and cleansing agents), trash, humidity condensate, perspiration and respiration water, trace contaminants, and dust generation. This report also reproduces the latest information on the environmental control and life support system design parameters for Space Station Freedom.

  4. Waste streams in a crewed space habitat II.

    PubMed

    Golub, M A; Wydeven, T

    1992-01-01

    A compilation of generation rates and chemical compositions of potential waste streams in a typical crewed space habitat, reported in a prior NASA Technical Memorandum and a related journal article, has been updated. This paper augments that compilation by the inclusion of the following new data: those uncovered since completion of the prior report; those obtained from Soviet literature relevant to life support issues; and those for various minor human body wastes not presented previously (saliva, flatus, hair, finger- and toenails, dried skin and skin secretions, tears and semen), but included here for purposes of completeness. These waste streams complement those discussed previously: toilet waste (urine, feces, etc.), hygiene water (laundry, shower/handwash, dishwash water and cleansing agents), trash, humidity condensate, perspiration and respiration water, trace contaminants and dust generation. This paper also reproduces the latest information on the environmental control and life support system design parameters for Space Station Freedom.

  5. Stream salamanders as indicators of stream quality in Maryland, USA

    USGS Publications Warehouse

    Southerland, M.T.; Jung, R.E.; Baxter, D.P.; Chellman, I.C.; Mercurio, G.; Volstad, J.H.

    2004-01-01

    Biological indicators are critical to the protection of small, headwater streams and the ecological values they provide. Maryland and other state monitoring programs have determined that fish indicators are ineffective in small streams, where stream salamanders may replace fish as top predators. Because of their life history, physiology, abundance, and ubiquity, stream salamanders are likely representative of biological integrity in these streams. The goal of this study was to determine whether stream salamanders are effective indicators of ecological conditions across biogeographic regions and gradients of human disturbance. During the summers of 2001 and 2002, we intensively surveyed for stream salamanders at 76 stream sites located west of the Maryland Coastal Plain, sites also monitored by the Maryland Biological Stream Survey (MBSS) and City of Gaithersburg. We found 1,584 stream salamanders, including all eight species known in Maryland, using two 15 ? 2 m transects and two 4 m2 quadrats that spanned both stream bank and channel. We performed removal sampling on transects to estimate salamander species detection probabilities, which ranged from 0.67-0.85. Stepwise regressions identified 15 of 52 non-salamander variables, representing water quality, physical habitat, land use, and biological conditions, which best predicted salamander metrics. Indicator development involved (1) identifying reference (non-degraded) and degraded sites (using percent forest, shading, riparian buffer width, aesthetic rating, and benthic macroinvertebrate and fish indices of biotic integrity); (2) testing 12 candidate salamander metrics (representing species richness and composition, abundance, species tolerance, and reproductive function) for their ability to distinguish reference from degraded sites; and (3) combining metrics into an index that effectively discriminated sites according to known stream conditions. Final indices for Highlands, Piedmont, and Non-Coastal Plain

  6. The Phoenix Stream: A Cold Stream in the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Balbinot, E.; Yanny, B.; Li, T. S.; Santiago, B.; Marshall, J. L.; Finley, D. A.; Pieres, A.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Benoit-Lévy, A.; Bernstein, G. M.; Bertin, E.; Brooks, D.; Burke, D. L.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Cunha, C. E.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Diehl, H. T.; Doel, P.; Estrada, J.; Flaugher, B.; Frieman, J.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Honscheid, K.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; March, M.; Martini, P.; Miquel, R.; Nichol, R. C.; Ogando, R.; Romer, A. K.; Sanchez, E.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Tarle, G.; Thomas, D.; Tucker, D.; Walker, A. R.; DES Collaboration

    2016-03-01

    We report the discovery of a stellar stream in the Dark Energy Survey Year 1 (Y1A1) data. The discovery was made through simple color-magnitude filters and visual inspection of the Y1A1 data. We refer to this new object as the Phoenix stream, after its resident constellation. After subtraction of the background stellar population we detect a clear signal of a simple stellar population. By fitting the ridge line of the stream in color-magnitude space, we find that a stellar population with age τ = 11.5 ± 0.5 Gyr and [Fe/H] < -1.6, located 17.5 ± 0.9 kpc from the Sun, gives an adequate description of the stream stellar population. The stream is detected over an extension of 8.°1 (2.5 kpc) and has a width of ˜54 pc assuming a Gaussian profile, indicating that a globular cluster (GC) is a probable progenitor. There is no known GC within 5 kpc that is compatible with being the progenitor of the stream, assuming that the stream traces its orbit. We examined overdensities (ODs) along the stream, however, no obvious counterpart-bound stellar system is visible in the coadded images. We also find ODs along the stream that appear to be symmetrically distributed—consistent with the epicyclic OD scenario for the formation of cold streams—as well as a misalignment between the northern and southern part of stream. Despite the close proximity we find no evidence that this stream and the halo cluster NGC 1261 have a common accretion origin linked to the recently found EriPhe OD.

  7. On the prior distribution of extinction time.

    PubMed

    Solow, Andrew R

    2016-06-01

    Bayesian inference about the extinction of a species based on a record of its sightings requires the specification of a prior distribution for extinction time. Here, I critically review some specifications in the context of a specific model of the sighting record. The practical implication of the choice of prior distribution is illustrated through an application to the sighting record of the Caribbean monk seal. PMID:27277952

  8. Varying prior information in Bayesian inversion

    NASA Astrophysics Data System (ADS)

    Walker, Matthew; Curtis, Andrew

    2014-06-01

    Bayes' rule is used to combine likelihood and prior probability distributions. The former represents knowledge derived from new data, the latter represents pre-existing knowledge; the Bayesian combination is the so-called posterior distribution, representing the resultant new state of knowledge. While varying the likelihood due to differing data observations is common, there are also situations where the prior distribution must be changed or replaced repeatedly. For example, in mixture density neural network (MDN) inversion, using current methods the neural network employed for inversion needs to be retrained every time prior information changes. We develop a method of prior replacement to vary the prior without re-training the network. Thus the efficiency of MDN inversions can be increased, typically by orders of magnitude when applied to geophysical problems. We demonstrate this for the inversion of seismic attributes in a synthetic subsurface geological reservoir model. We also present results which suggest that prior replacement can be used to control the statistical properties (such as variance) of the final estimate of the posterior in more general (e.g., Monte Carlo based) inverse problem solutions.

  9. An approach to prior austenite reconstruction

    SciTech Connect

    Abbasi, Majid; Nelson, Tracy W.; Sorensen, Carl D.; Wei Lingyun

    2012-04-15

    One area of interest in Friction Stir Welding (FSW) of steels is to understand microstructural evolution during the process. Most of the deformation occurs in the austenite temperature range. Quantitative microstructural measurements of prior austenite microstructure are needed in order to understand evolution of the microstructure. Considering the fact that room temperature microstructure in ferritic steels contains very little to no retained austenite, prior austenite microstructure needs to be recovered from the room temperature ferrite. In this paper, an approach based on Electron Backscattered Diffraction (EBSD) is introduced to detect Bain zones. Bain zone detection is used to reconstruct prior austenite grain structure. Additionally, a separate approach based on phase transformation orientation relationships is introduced in order to recover prior austenite orientation. - Highlights: Black-Right-Pointing-Pointer This approach provides a tool to reconstruct large-scale austenite microstructures. Black-Right-Pointing-Pointer It recovers prior austenite orientation without relying on retained austenite. Black-Right-Pointing-Pointer It utilizes EBSD data from the room temperature microstructure. Black-Right-Pointing-Pointer Higher number of active variants leads to more accurate reconstructions. Black-Right-Pointing-Pointer At least two variants are needed in order to recover prior austenite orientation.

  10. Attentional and Contextual Priors in Sound Perception

    PubMed Central

    Wolmetz, Michael; Elhilali, Mounya

    2016-01-01

    Behavioral and neural studies of selective attention have consistently demonstrated that explicit attentional cues to particular perceptual features profoundly alter perception and performance. The statistics of the sensory environment can also provide cues about what perceptual features to expect, but the extent to which these more implicit contextual cues impact perception and performance, as well as their relationship to explicit attentional cues, is not well understood. In this study, the explicit cues, or attentional prior probabilities, and the implicit cues, or contextual prior probabilities, associated with different acoustic frequencies in a detection task were simultaneously manipulated. Both attentional and contextual priors had similarly large but independent impacts on sound detectability, with evidence that listeners tracked and used contextual priors for a variety of sound classes (pure tones, harmonic complexes, and vowels). Further analyses showed that listeners updated their contextual priors rapidly and optimally, given the changing acoustic frequency statistics inherent in the paradigm. A Bayesian Observer model accounted for both attentional and contextual adaptations found with listeners. These results bolster the interpretation of perception as Bayesian inference, and suggest that some effects attributed to selective attention may be a special case of contextual prior integration along a feature axis. PMID:26882228

  11. Attentional and Contextual Priors in Sound Perception.

    PubMed

    Wolmetz, Michael; Elhilali, Mounya

    2016-01-01

    Behavioral and neural studies of selective attention have consistently demonstrated that explicit attentional cues to particular perceptual features profoundly alter perception and performance. The statistics of the sensory environment can also provide cues about what perceptual features to expect, but the extent to which these more implicit contextual cues impact perception and performance, as well as their relationship to explicit attentional cues, is not well understood. In this study, the explicit cues, or attentional prior probabilities, and the implicit cues, or contextual prior probabilities, associated with different acoustic frequencies in a detection task were simultaneously manipulated. Both attentional and contextual priors had similarly large but independent impacts on sound detectability, with evidence that listeners tracked and used contextual priors for a variety of sound classes (pure tones, harmonic complexes, and vowels). Further analyses showed that listeners updated their contextual priors rapidly and optimally, given the changing acoustic frequency statistics inherent in the paradigm. A Bayesian Observer model accounted for both attentional and contextual adaptations found with listeners. These results bolster the interpretation of perception as Bayesian inference, and suggest that some effects attributed to selective attention may be a special case of contextual prior integration along a feature axis.

  12. Removal of particulate matter from combustion gas streams

    SciTech Connect

    Krigmont, H.V.; Coe, E.L. Jr.

    1991-01-29

    This patent describes an apparatus for removing particulate matter from a combustion gas stream that is passed through an electrostatic precipitator having precipitating elements therein. It comprises: first means for selectively injecting a controllably variable amount of a conditioning agent into a combustion gas stream at a location prior to the entry of the combustion gas into an electrostatic precipitator; second means for establishing the duty cycle of the power provided to a precipitating element in the electrostatic precipitator; third means for measuring the relative particulate content of the combustion gas stream after it leaves the electrostatic precipitator; and fourth means for controlling the first means and the second means in response to the measurement derived from the third means.

  13. Analyzing indicators of stream health for Minnesota streams

    USGS Publications Warehouse

    Singh, U.; Kocian, M.; Wilson, B.; Bolton, A.; Nieber, J.; Vondracek, B.; Perry, J.; Magner, J.

    2005-01-01

    Recent research has emphasized the importance of using physical, chemical, and biological indicators of stream health for diagnosing impaired watersheds and their receiving water bodies. A multidisciplinary team at the University of Minnesota is carrying out research to develop a stream classification system for Total Maximum Daily Load (TMDL) assessment. Funding for this research is provided by the United States Environmental Protection Agency and the Minnesota Pollution Control Agency. One objective of the research study involves investigating the relationships between indicators of stream health and localized stream characteristics. Measured data from Minnesota streams collected by various government and non-government agencies and research institutions have been obtained for the research study. Innovative Geographic Information Systems tools developed by the Environmental Science Research Institute and the University of Texas are being utilized to combine and organize the data. Simple linear relationships between index of biological integrity (IBI) and channel slope, two-year stream flow, and drainage area are presented for the Redwood River and the Snake River Basins. Results suggest that more rigorous techniques are needed to successfully capture trends in IBI scores. Additional analyses will be done using multiple regression, principal component analysis, and clustering techniques. Uncovering key independent variables and understanding how they fit together to influence stream health are critical in the development of a stream classification for TMDL assessment.

  14. ASSESSING STREAM BED STABILITY AND EXCESS SEDIMENTATION IN MOUNTAIN STREAMS

    EPA Science Inventory

    Land use and resource exploitation in headwaters catchments?such as logging, mining, and road building?often increase sediment supply to streams, potentially causing excess sedimentation. Decreases in mean substrate size and increases in fine stream bed sediments can lead to inc...

  15. Sorbent-based sampling methods for volatile and semi-volatile organic compounds in air Part 1: Sorbent-based air monitoring options.

    PubMed

    Woolfenden, Elizabeth

    2010-04-16

    Sorbent tubes/traps are widely used in combination with gas chromatographic (GC) analytical methods to monitor the vapour-phase fraction of organic compounds in air. Target compounds range in volatility from acetylene and freons to phthalates and PCBs and include apolar, polar and reactive species. Airborne vapour concentrations will vary depending on the nature of the location, nearby pollution sources, weather conditions, etc. Levels can range from low percent concentrations in stack and vent emissions to low part per trillion (ppt) levels in ultra-clean outdoor locations. Hundreds, even thousands of different compounds may be present in any given atmosphere. GC is commonly used in combination with mass spectrometry (MS) detection especially for environmental monitoring or for screening uncharacterised workplace atmospheres. Given the complexity and variability of organic vapours in air, no one sampling approach suits every monitoring scenario. A variety of different sampling strategies and sorbent media have been developed to address specific applications. Key sorbent-based examples include: active (pumped) sampling onto tubes packed with one or more sorbents held at ambient temperature; diffusive (passive) sampling onto sorbent tubes/cartridges; on-line sampling of air/gas streams into cooled sorbent traps; and transfer of air samples from containers (canisters, Tedlar) bags, etc.) into cooled sorbent focusing traps. Whichever sampling approach is selected, subsequent analysis almost always involves either solvent extraction or thermal desorption (TD) prior to GC(/MS) analysis. The overall performance of the air monitoring method will depend heavily on appropriate selection of key sampling and analytical parameters. This comprehensive review of air monitoring using sorbent tubes/traps is divided into 2 parts. (1) Sorbent-based air sampling option. (2) Sorbent selection and other aspects of optimizing sorbent-based air monitoring methods. The paper presents

  16. Air Abrasion

    MedlinePlus

    ... delivered directly to your desktop! more... What Is Air Abrasion? Article Chapters What Is Air Abrasion? What Happens? The Pros and Cons Will I Feel Anything? Is Air Abrasion for Everyone? print full article print this ...

  17. Solute specific scaling of inorganic nitrogen and phosphorus uptake in streams

    NASA Astrophysics Data System (ADS)

    Hall, R. O., Jr.; Baker, M. A.; Rosi-Marshall, E. J.; Tank, J. L.

    2013-04-01

    Stream ecosystem processes such as nutrient cycling may vary with stream position in the watershed. Using a scaling approach, we examined the relationship between stream size and nutrient uptake length, which represents the mean distance that a dissolved solute travels prior to removal from the water column. Ammonium uptake length increased proportionally with stream size measured as specific discharge (discharge/stream width) with a scaling exponent = 1.01. In contrast, the scaling exponent for nitrate (NO3-) was 1.19 and for soluble reactive phosphorus (SRP) was 1.35, suggesting that uptake lengths for these nutrients increased more rapidly than increases in specific discharge. Additionally, the ratio of nitrogen (N) uptake length to SRP uptake length declined with stream size; there was lower demand for SRP relative to N as stream size increased. Ammonium and NO3- uptake velocity positively related with stream metabolism, while SRP did not. Finally, we related the scaling of uptake length and specific discharge to that of stream length using Hack's law and downstream hydraulic geometry. Ammonium uptake length increased less than proportionally with distance from the headwaters, suggesting a strong role for larger streams and rivers in regulating nutrient transport.

  18. Air Quality Monitor

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The Stak-Tracker CEM (Continuous Emission Monitor) Gas Analyzer is an air quality monitor capable of separating the various gases in a bulk exhaust stream and determining the amounts of individual gases present within the stream. The monitor is produced by GE Reuter- Stokes, a subsidiary of GE Corporate Research & Development Center. The Stak-Tracker uses a Langley Research Center software package which measures the concentration of a target gas by determining the degree to which molecules of that gas absorb an infrared beam. The system is environmental-friendly, fast and has relatively low installation and maintenance costs. It is applicable to gas turbines and various industries including glass, paper and cement.

  19. Investigation of the impact of extreme air temperature on river water temperature: case study of the heat episode 2013.

    NASA Astrophysics Data System (ADS)

    Weihs, Philipp; Trimmel, Heidelinde; Goler, Robert; Formayer, Herbert; Holzapfel, Gerda; Rauch, Hans Peter

    2014-05-01

    Water stream temperature is a relevant factor for water quality since it is an important driver of water oxygen content and in turn also reduces or increases stress on the aquatic fauna. The water temperature of streams is determined by the source and inflow water temperature, by the energy balance at the stream surface and by the hydrological regime of the stream. Main factors driving the energy balance of streams are radiation balance and air temperature which influences the sensitive and latent heat flux. The present study investigates the impact of the heat episode of summer 2013 on water temperature of two lowland rivers in south eastern Austria. Within the scope of the project BIO_CLIC routine measurements of water temperature at 33 locations alongside the rivers Pinka and Lafnitz have been performed since spring 2012. In addition meteorological measurements of global shortwave and longwave radiation, air temperature, wind and air humidity have been carried out during this time. For the same time period, data of discharge and water levels of both rivers were provided by the public hydrological office. The heat episode of summer 2013 started, according to the Kysely- definition, on 18 July and lasted until 14 August. The highest air temperature ever recorded in Austria was reported on 8 August at 40.5°C. In Güssing, which is located within the project area, 40.0 °C were recorded. In the lower reaches of the river Pinka, at the station Burg the monthly mean water temperature of August 2013 was with more than 22°C, 1°C higher than the mean water temperature of the same period of the previous years. At the same station, the maximum water temperature of 27.1°C was recorded on 29 July, 9 days prior to the air temperature record. Analysis shows that at the downstream stations the main driving parameter is solar radiation whereas at the upstream stations a better correlation between air temperature and water temperature is obtained. Using the extensive data set

  20. Aircraft and runway deicers at General Mitchell International Airport, Milwaukee, Wisconsin, USA. 1. Biochemical oxygen demand and dissolved oxygen in receiving streams

    USGS Publications Warehouse

    Corsi, S.R.; Booth, N.L.; Hall, D.W.

    2001-01-01

    Aircraft and runway deicers are used during cold weather at many of the world's airports to facilitate safe air travel. Propylene glycol-, ethylene glycol-, and urea-based deicers are known to have very high biochemical oxygen demand. At General Mitchell International Airport (GMIA) in Milwaukee, Wisconsin, USA, deicer application, water chemistry, and dissolved oxygen (DO) data were collected for two deicing seasons in order to evaluate and define premanagement water quality parameters prior to the implementation of a glycol management program. Calculations using stream-monitoring data during a controlled release of deicer provided an estimate of 0.8/d for the first-order decay rate constant, substantially higher than published laboratory test results. For eight precipitation events with deicing activities, between 2.4 and 99% of propylene and ethylene glycol applied to aircraft was delivered directly to receiving streams. The percentage of glycol runoff during an event increased with increasing storm-flow volume. Elevated concentrations of glycol and biochemical oxygen demand were measured downstream from the airport. However, the frequency of low DO concentrations in the receiving streams is comparable with that at an upstream reference site. This is possibly due to slowed bacteria metabolism at low water temperatures, short travel times, and dilution from downstream tributaries.

  1. Aircraft and runway deicers at General Mitchell International Airport, Milwaukee, Wisconsin, USA. 1. Biochemical oxygen demand and dissolved oxygen in receiving streams.

    PubMed

    Corsi, S R; Booth, N L; Hall, D W

    2001-07-01

    Aircraft and runway deicers are used during cold weather at many of the world's airports to facilitate safe air travel. Propylene glycol-, ethylene glycol-, and urea-based deicers are known to have very high biochemical oxygen demand. At General Mitchell International Airport (GMIA) in Milwaukee, Wisconsin, USA, deicer application, water chemistry, and dissolved oxygen (DO) data were collected for two deicing seasons in order to evaluate and define premanagement water quality parameters prior to the implementation of a glycol management program. Calculations using stream-monitoring data during a controlled release of deicer provided an estimate of 0.8/d for the first-order decay rate constant, substantially higher than published laboratory test results. For eight precipitation events with deicing activities, between 2.4 and 99% of propylene and ethylene glycol applied to aircraft was delivered directly to receiving streams. The percentage of glycol runoff during an event increased with increasing storm-flow volume. Elevated concentrations of glycol and biochemical oxygen demand were measured downstream from the airport. However, the frequency of low DO concentrations in the receiving streams is comparable with that at an upstream reference site. This is possibly due to slowed bacteria metabolism at low water temperatures, short travel times, and dilution from downstream tributaries.

  2. Human impacts to mountain streams

    NASA Astrophysics Data System (ADS)

    Wohl, Ellen

    2006-09-01

    Mountain streams are here defined as channel networks within mountainous regions of the world. This definition encompasses tremendous diversity of physical and biological conditions, as well as history of land use. Human effects on mountain streams may result from activities undertaken within the stream channel that directly alter channel geometry, the dynamics of water and sediment movement, contaminants in the stream, or aquatic and riparian communities. Examples include channelization, construction of grade-control structures or check dams, removal of beavers, and placer mining. Human effects can also result from activities within the watershed that indirectly affect streams by altering the movement of water, sediment, and contaminants into the channel. Deforestation, cropping, grazing, land drainage, and urbanization are among the land uses that indirectly alter stream processes. An overview of the relative intensity of human impacts to mountain streams is provided by a table summarizing human effects on each of the major mountainous regions with respect to five categories: flow regulation, biotic integrity, water pollution, channel alteration, and land use. This table indicates that very few mountains have streams not at least moderately affected by land use. The least affected mountainous regions are those at very high or very low latitudes, although our scientific ignorance of conditions in low-latitude mountains in particular means that streams in these mountains might be more altered than is widely recognized. Four case studies from northern Sweden (arctic region), Colorado Front Range (semiarid temperate region), Swiss Alps (humid temperate region), and Papua New Guinea (humid tropics) are also used to explore in detail the history and effects on rivers of human activities in mountainous regions. The overview and case studies indicate that mountain streams must be managed with particular attention to upstream/downstream connections, hillslope

  3. Variability of Methane in Stordalen Mire Stream Sediments, Abisko, Sweden

    NASA Astrophysics Data System (ADS)

    Nicastro, A. J. D.; Horruitiner, C. D.; Lundgren, D. J.; Sinclair, S. N.; Johnson, J. E.; Varner, R. K.

    2015-12-01

    Methane emissions from Stordalen Mire in subarctic Sweden have been increasing over the last century with rising atmospheric temperatures. Methane emissions from lakes in this region have shown a positive correlation with sediment and air temperatures. Previous studies have examined CH4 emissions of these lakes but the primary stream that flows along the edge the mire is understudied. Streams and rivers that exist in permafrost peatland environments are thought to be a pathway for the release of older carbon deposits from thawing permafrost. To understand the potential role of stream morphology and stratigraphy on CH4 concentrations and contributions to carbon cycling in this system, seven sediment cores were extracted from the stream and one from the adjacent lake. Cores were subsampled at 5cm depth intervals and analyzed for CH4 concentration, δ13CH4 isotopes, elemental CHNS and sediment grain size. Results from these analyses show that maximum CH4 concentrations in stream sediments occur at greater depths than in the adjacent lake sediments. Higher CH4 concentrations are observed in organic C rich layers in both environments. However, in stream sediments, CH4 appears to be produced within some stratigraphic intervals, but exists in others as the result of transport. Organic C/N ratios of the sediments indicate a predominance of terrestrial organic C but it is unclear whether the sediment organic C is the result of deposition of C from permafrost thaw or C that was deposited through the degradation of modern plant material.

  4. Source apportionment modeling of volatile organic compounds in streams.

    PubMed

    Pankow, James F; Asher, William E; Zogorski, John S

    2006-04-01

    It often is of interest to understand the relative importance of the different sources contributing to the concentration c(w) of a contaminant in a stream; the portions related to sources 1, 2, 3, etc. are denoted c(w,1), c(w2), c(w3), etc. Like c(w), the fractions alpha1 = c(w,1)/c(w), alpha2 = c(w,2)/c(w), alpha3 = c(w,3)/c(w), etc. depend on location and time. Volatile organic compounds (VOCs) can undergo absorption from the atmosphere into stream water or loss from stream water to the atmosphere, causing complexities affecting the source apportionment (SA) of VOCs in streams. Two SA rules are elaborated. Rule 1: VOC entering a stream across the air/water interface exclusively is assigned to the atmospheric portion of c(w). Rule 2: VOC loss by volatilization, flow loss to groundwater, in-stream degradation, etc. is distributed over c(w,1), c(w,2), c(w3), etc. in proportion to their corresponding alpha values. How the two SA rules are applied, as well as the nature of the SA output for a given case, will depend on whether transport across the air/water interface is handled using the net flux F convention or using the individual fluxes J convention. Four hypothetical stream cases involving acetone, methyl-tert-butyl ether (MTBE), benzene, chloroform, and perchloroethylene (PCE) are considered. Acetone and MTBE are sufficiently water soluble from air for a domestic atmospheric source to be capable of yielding c(w) values approaching the common water quality guideline range of 1 to 10 microg/L. For most other VOCs, such levels cause net outgassing (F > 0). When F > 0 in a given section of stream, in the net flux convention, all of the alpha(j) for the compound remain unchanged over that section while c(w) decreases. A characteristic time tau(d) can be calculated to predict when there will be differences between SA results obtained by the net flux convention versus the individual fluxes convention. Source apportionment modeling provides the framework necessary for

  5. Source apportionment modeling of volatile organic compounds in streams

    USGS Publications Warehouse

    Pankow, J.F.; Asher, W.E.; Zogorski, J.S.

    2006-01-01

    It often is of interest to understand the relative importance of the different sources contributing to the concentration cw of a contaminant in a stream; the portions related to sources 1, 2, 3, etc. are denoted cw,1, cw,2, cw,3, etc. Like c w, 'he fractions ??1, = cw,1/c w, ??2 = cw,2/cw, ??3 = cw,3/cw, etc. depend on location and time. Volatile organic compounds (VOCs) can undergo absorption from the atmosphere into stream water or loss from stream water to the atmosphere, causing complexities affecting the source apportionment (SA) of VOCs in streams. Two SA rules are elaborated. Rule 1: VOC entering a stream across the air/water interface exclusively is assigned to the atmospheric portion of cw. Rule 2: VOC loss by volatilization, flow loss to groundwater, in-stream degradation, etc. is distributed over cw,1 cw,2, c w,3, etc. in proportion to their corresponding ?? values. How the two SA rules are applied, as well as the nature of the SA output for a given case, will depend on whether transport across the air/water interface is handled using the net flux F convention or using the individual fluxes J convention. Four hypothetical stream cases involving acetone, methyl-tert-butyl ether (MTBE), benzene, chloroform, and perchloroethylene (PCE) are considered. Acetone and MTBE are sufficiently water soluble from air for a domestic atmospheric source to be capable of yielding cw values approaching the common water quality guideline range of 1 to 10 ??g/L. For most other VOCs, such levels cause net outgassing (F > 0). When F > 0 in a given section of stream, in the net flux convention, all of the ??j, for the compound remain unchanged over that section while cw decreases. A characteristic time ??d can be calculated to predict when there will be differences between SA results obtained by the net flux convention versus the individual fluxes convention. Source apportionment modeling provides the framework necessary for comparing different strategies for mitigating

  6. Stream, Lake, and Reservoir Management.

    PubMed

    Mei, Ying; Chang, Chein-Chi; Dong, Zhanfeng; Wei, Li

    2016-10-01

    This review on stream, lake, and reservoir management covers selected 2015 publications on the focus of the following sections: • Biota • Climate effect • Models • Remediation and restoration • Reservoir operations • Stream, Lake, and Reservoir Management • Water quality.

  7. We All Stream for Video

    ERIC Educational Resources Information Center

    Technology & Learning, 2008

    2008-01-01

    More than ever, teachers are using digital video to enhance their lessons. In fact, the number of schools using video streaming increased from 30 percent to 45 percent between 2004 and 2006, according to Market Data Retrieval. Why the popularity? For starters, video-streaming products are easy to use. They allow teachers to punctuate lessons with…

  8. Save Our Streams and Waterways.

    ERIC Educational Resources Information Center

    Indiana State Dept. of Education, Indianapolis. Center for School Improvement and Performance.

    Protection of existing water supplies is critical to ensuring good health for people and animals alike. This program is aligned with the Izaak Walton League of American's Save Our Streams program which is based on the concept that students can greatly improve the quality of a nearby stream, pond, or river by regular visits and monitoring. The…

  9. Industrial-Strength Streaming Video.

    ERIC Educational Resources Information Center

    Avgerakis, George; Waring, Becky

    1997-01-01

    Corporate training, financial services, entertainment, and education are among the top applications for streaming video servers, which send video to the desktop without downloading the whole file to the hard disk, saving time and eliminating copyrights questions. Examines streaming video technology, lists ten tips for better net video, and ranks…

  10. Stream, Lake, and Reservoir Management.

    PubMed

    Mei, Ying; Chang, Chein-Chi; Dong, Zhanfeng; Wei, Li

    2016-10-01

    This review on stream, lake, and reservoir management covers selected 2015 publications on the focus of the following sections: • Biota • Climate effect • Models • Remediation and restoration • Reservoir operations • Stream, Lake, and Reservoir Management • Water quality. PMID:27620102

  11. Simulation forecasts complex flow streams from Ekofisk

    SciTech Connect

    Arnes, F.C.; Lillejord, H.

    1996-10-28

    A commercial steady-state process flowsheet simulation program serves as the basis for a rigorous calculation model for predicting produced flow rates from the Ekofisk complex in the Norwegian sector of the North Sea. The complex is the center of an extensive gathering system that collects oil and gas streams from several producing fields. Prior to running a production forecast, the simulation model is initiated by matching several years of production. Once the simulation model matches historical production data within acceptable limits, it then is driven by production forecasts from reservoir simulations to develop long-term forecasts of gas, NGL, and oil production. The paper describes the Ekofisk field, the process simulation, implementation of the model, and problems encountered.

  12. FireHose Streaming Benchmarks

    SciTech Connect

    Karl Anderson, Steve Plimpton

    2015-01-27

    The FireHose Streaming Benchmarks are a suite of stream-processing benchmarks defined to enable comparison of streaming software and hardware, both quantitatively vis-a-vis the rate at which they can process data, and qualitatively by judging the effort involved to implement and run the benchmarks. Each benchmark has two parts. The first is a generator which produces and outputs datums at a high rate in a specific format. The second is an analytic which reads the stream of datums and is required to perform a well-defined calculation on the collection of datums, typically to find anomalous datums that have been created in the stream by the generator. The FireHose suite provides code for the generators, sample code for the analytics (which users are free to re-implement in their own custom frameworks), and a precise definition of each benchmark calculation.

  13. Quantities and characteristics of the contact-handled low-level mixed waste streams for the DOE complex

    SciTech Connect

    Huebner, T.L.; Wilson, J.M.; Ruhter, A.H.; Bonney, S.J.

    1994-08-01

    This report supports the Integrated Thermal Treatment System (ITTS) Study initiated by the Department of Energy (DOE) Office of Technology Development (EM-50), which is a system engineering assessment of a variety of mixed waste treatment process. The DOE generates and stores large quantities of mixed wastes that are contaminated with both chemically hazardous and radioactive species. The treatment of these mixed wastes requires meeting the standards established by the Environmental Protection Agency for the specific hazardous contaminants regulated under the Resource Conservation and Recovery Act while also providing adequate control of the radionuclides. The thrust of the study is to develop preconceptual designs and life-cycle cost estimates for integrated thermal treatment systems ranging from conventional incinerators, such as rotary kiln and controlled air systems, to more innovative but not yet established technologies, such as molten salt and molten metal waste destruction systems. Prior to this engineering activity, the physical and chemical characteristics of the DOE low-level mixed waste streams to be treated must be defined or estimated. This report describes efforts to estimate the DOE waste stream characteristics.

  14. 21 CFR 874.1800 - Air or water caloric stimulator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Diagnostic Devices § 874.1800 Air or water caloric stimulator. (a) Identification. An air or water caloric stimulator is a device that delivers a stream of air...) Classification. Class I (general controls). The device is exempt from the premarket notification procedures...

  15. Commissioning of the PRIOR proton microscope

    DOE PAGES

    Varentsov, D.; Antonov, O.; Bakhmutova, A.; Barnes, C. W.; Bogdanov, A.; Danly, C. R.; Efimov, S.; Endres, M.; Fertman, A.; Golubev, A. A.; et al

    2016-02-18

    Recently, a new high energy proton microscopy facility PRIOR (Proton Microscope for FAIR Facility for Anti-proton and Ion Research) has been designed, constructed, and successfully commissioned at GSI Helmholtzzentrum für Schwerionenforschung (Darmstadt, Germany). As a result of the experiments with 3.5–4.5 GeV proton beams delivered by the heavy ion synchrotron SIS-18 of GSI, 30 μm spatial and 10 ns temporal resolutions of the proton microscope have been demonstrated. A new pulsed power setup for studying properties of matter under extremes has been developed for the dynamic commissioning of the PRIOR facility. This study describes the PRIOR setup as well asmore » the results of the first static and dynamic protonradiography experiments performed at GSI.« less

  16. Commissioning of the PRIOR proton microscope.

    PubMed

    Varentsov, D; Antonov, O; Bakhmutova, A; Barnes, C W; Bogdanov, A; Danly, C R; Efimov, S; Endres, M; Fertman, A; Golubev, A A; Hoffmann, D H H; Ionita, B; Kantsyrev, A; Krasik, Ya E; Lang, P M; Lomonosov, I; Mariam, F G; Markov, N; Merrill, F E; Mintsev, V B; Nikolaev, D; Panyushkin, V; Rodionova, M; Schanz, M; Schoenberg, K; Semennikov, A; Shestov, L; Skachkov, V S; Turtikov, V; Udrea, S; Vasylyev, O; Weyrich, K; Wilde, C; Zubareva, A

    2016-02-01

    Recently, a new high energy proton microscopy facility PRIOR (Proton Microscope for FAIR Facility for Anti-proton and Ion Research) has been designed, constructed, and successfully commissioned at GSI Helmholtzzentrum für Schwerionenforschung (Darmstadt, Germany). As a result of the experiments with 3.5-4.5 GeV proton beams delivered by the heavy ion synchrotron SIS-18 of GSI, 30 μm spatial and 10 ns temporal resolutions of the proton microscope have been demonstrated. A new pulsed power setup for studying properties of matter under extremes has been developed for the dynamic commissioning of the PRIOR facility. This paper describes the PRIOR setup as well as the results of the first static and dynamic proton radiography experiments performed at GSI. PMID:26931841

  17. Commissioning of the PRIOR proton microscope

    NASA Astrophysics Data System (ADS)

    Varentsov, D.; Antonov, O.; Bakhmutova, A.; Barnes, C. W.; Bogdanov, A.; Danly, C. R.; Efimov, S.; Endres, M.; Fertman, A.; Golubev, A. A.; Hoffmann, D. H. H.; Ionita, B.; Kantsyrev, A.; Krasik, Ya. E.; Lang, P. M.; Lomonosov, I.; Mariam, F. G.; Markov, N.; Merrill, F. E.; Mintsev, V. B.; Nikolaev, D.; Panyushkin, V.; Rodionova, M.; Schanz, M.; Schoenberg, K.; Semennikov, A.; Shestov, L.; Skachkov, V. S.; Turtikov, V.; Udrea, S.; Vasylyev, O.; Weyrich, K.; Wilde, C.; Zubareva, A.

    2016-02-01

    Recently, a new high energy proton microscopy facility PRIOR (Proton Microscope for FAIR Facility for Anti-proton and Ion Research) has been designed, constructed, and successfully commissioned at GSI Helmholtzzentrum für Schwerionenforschung (Darmstadt, Germany). As a result of the experiments with 3.5-4.5 GeV proton beams delivered by the heavy ion synchrotron SIS-18 of GSI, 30 μm spatial and 10 ns temporal resolutions of the proton microscope have been demonstrated. A new pulsed power setup for studying properties of matter under extremes has been developed for the dynamic commissioning of the PRIOR facility. This paper describes the PRIOR setup as well as the results of the first static and dynamic proton radiography experiments performed at GSI.

  18. Dynamical modeling of tidal streams

    SciTech Connect

    Bovy, Jo

    2014-11-01

    I present a new framework for modeling the dynamics of tidal streams. The framework consists of simple models for the initial action-angle distribution of tidal debris, which can be straightforwardly evolved forward in time. Taking advantage of the essentially one-dimensional nature of tidal streams, the transformation to position-velocity coordinates can be linearized and interpolated near a small number of points along the stream, thus allowing for efficient computations of a stream's properties in observable quantities. I illustrate how to calculate the stream's average location (its 'track') in different coordinate systems, how to quickly estimate the dispersion around its track, and how to draw mock stream data. As a generative model, this framework allows one to compute the full probability distribution function and marginalize over or condition it on certain phase-space dimensions as well as convolve it with observational uncertainties. This will be instrumental in proper data analysis of stream data. In addition to providing a computationally efficient practical tool for modeling the dynamics of tidal streams, the action-angle nature of the framework helps elucidate how the observed width of the stream relates to the velocity dispersion or mass of the progenitor, and how the progenitors of 'orphan' streams could be located. The practical usefulness of the proposed framework crucially depends on the ability to calculate action-angle variables for any orbit in any gravitational potential. A novel method for calculating actions, frequencies, and angles in any static potential using a single orbit integration is described in the Appendix.

  19. Dynamical Modeling of Tidal Streams

    NASA Astrophysics Data System (ADS)

    Bovy, Jo

    2014-11-01

    I present a new framework for modeling the dynamics of tidal streams. The framework consists of simple models for the initial action-angle distribution of tidal debris, which can be straightforwardly evolved forward in time. Taking advantage of the essentially one-dimensional nature of tidal streams, the transformation to position-velocity coordinates can be linearized and interpolated near a small number of points along the stream, thus allowing for efficient computations of a stream's properties in observable quantities. I illustrate how to calculate the stream's average location (its "track") in different coordinate systems, how to quickly estimate the dispersion around its track, and how to draw mock stream data. As a generative model, this framework allows one to compute the full probability distribution function and marginalize over or condition it on certain phase-space dimensions as well as convolve it with observational uncertainties. This will be instrumental in proper data analysis of stream data. In addition to providing a computationally efficient practical tool for modeling the dynamics of tidal streams, the action-angle nature of the framework helps elucidate how the observed width of the stream relates to the velocity dispersion or mass of the progenitor, and how the progenitors of "orphan" streams could be located. The practical usefulness of the proposed framework crucially depends on the ability to calculate action-angle variables for any orbit in any gravitational potential. A novel method for calculating actions, frequencies, and angles in any static potential using a single orbit integration is described in the Appendix.

  20. Low-flow characteristics of Indiana streams

    USGS Publications Warehouse

    Fowler, K.K.; Wilson, J.T.

    1996-01-01

    Knowledge of low-flow characteristics of streams is essential for management of water resources. Low-flow characteristics are presented for 229 continuous-record, streamflow-gaging stations and 285 partial-record stations in Indiana. Low- flow-frequency characteristics were computed for 210 continuous-record stations that had at least 10 years of record, and flow-duration curves were computed for all continuous-record stations. Low-flow-frequency and flow-duration analyses are based on available streamflow records through September 1993. Selected low-flow-frequency curves were computed for annual low flows and seasonal low flows. The four seasons are represented by the 3-month groups of March-May, June-August, September-November, and December- February. The 7-day, 10-year and the 7-day, 2 year low flows were estimated for 285 partial-record stations, which are ungaged sites where streamflow measurements were made at base flow. The same low-flow characteristics were estimated for 19 continuous-record stations where less than 10 years of record were available. Precipitation and geology directly influence the streams in Indiana. Streams in the northern, glaciated part of the State tend to have higher sustained base flows than those in the nonglaciated southern part. Flow at several of the continuous-record gaging stations is affected by some form of regulation or diversion. Low-flow characteristics for continuous-record stations at which flow is affected by regulation are determined using the period of record affected by regulation; natural flows prior to regulation are not used.

  1. Method for treating a nuclear process off-gas stream

    DOEpatents

    Pence, Dallas T.; Chou, Chun-Chao

    1984-01-01

    Disclosed is a method for selectively removing and recovering the noble gas and other gaseous components typically emitted during nuclear process operations. The method is adaptable and useful for treating dissolver off-gas effluents released during reprocessing of spent nuclear fuels whereby to permit radioactive contaminant recovery prior to releasing the remaining off-gases to the atmosphere. Briefly, the method sequentially comprises treating the off-gas stream to preliminarily remove NO.sub.x, hydrogen and carbon-containing organic compounds, and semivolatile fission product metal oxide components therefrom; adsorbing iodine components on silver-exchanged mordenite; removing water vapor carried by said stream by means of a molecular sieve; selectively removing the carbon dioxide components of said off-gas stream by means of a molecular sieve; selectively removing xenon in gas phase by passing said stream through a molecular sieve comprising silver-exchanged mordenite; selectively separating krypton from oxygen by means of a molecular sieve comprising silver-exchanged mordenite; selectively separating krypton from the bulk nitrogen stream using a molecular sieve comprising silver-exchanged mordenite cooled to about -140.degree. to -160.degree. C.; concentrating the desorbed krypton upon a molecular sieve comprising silver-exchange mordenite cooled to about -140.degree. to -160.degree. C.; and further cryogenically concentrating, and the recovering for storage, the desorbed krypton.

  2. The paradox of cooling streams in a warming world: regional climate trends do not parallel variable local trends in stream temperature in the Pacific continental United States

    USGS Publications Warehouse

    Arismendi, Ivan; Johnson, Sherri; Dunham, Jason B.; Haggerty, Roy; Hockman-Wert, David

    2012-01-01

    Temperature is a fundamentally important driver of ecosystem processes in streams. Recent warming of terrestrial climates around the globe has motivated concern about consequent increases in stream temperature. More specifically, observed trends of increasing air temperature and declining stream flow are widely believed to result in corresponding increases in stream temperature. Here, we examined the evidence for this using long-term stream temperature data from minimally and highly human-impacted sites located across the Pacific continental United States. Based on hypothesized climate impacts, we predicted that we should find warming trends in the maximum, mean and minimum temperatures, as well as increasing variability over time. These predictions were not fully realized. Warming trends were most prevalent in a small subset of locations with longer time series beginning in the 1950s. More recent series of observations (1987-2009) exhibited fewer warming trends and more cooling trends in both minimally and highly human-influenced systems. Trends in variability were much less evident, regardless of the length of time series. Based on these findings, we conclude that our perspective of climate impacts on stream temperatures is clouded considerably by a lack of long-termdata on minimally impacted streams, and biased spatio-temporal representation of existing time series. Overall our results highlight the need to develop more mechanistic, process-based understanding of linkages between climate change, other human impacts and stream temperature, and to deploy sensor networks that will provide better information on trends in stream temperatures in the future.

  3. New insights into West Greenland ice sheet/stream dynamics during the last glacial cycle.

    NASA Astrophysics Data System (ADS)

    Roberts, David; Lane, Tim; Rea, Brice; Cofaigh, Colm O.; Jamieson, Stewart; Vieli, Andreas; Rodes, Angel

    2015-04-01

    Onshore and offshore geomorphological mapping and deglacial chronologies from West Greenland constrain the nature and magnitude of ice advance and decay of the Greenland Ice Sheet (GrIS) during the last glacial cycle. Several ice stream troughs are known to have fed ice to the shelf edge during the last glacial cycle. Their offshore expression suggests that many were coalescent systems fed by smaller outlet glaciers and ice streams onshore but their central flow pathways were also controlled by geology and preglacial topography. The bed morphology of these large ice streams shows they operated over soft, deforming beds with drumlins, mega-scale glacial lineations and grounding zone wedges marking an offshore transition from predominant areal scour onshore. Records of offshore deglacial chronology remain sparse but the Uummannaq and Disko Bugt ice stream corridors are now well constrained. The Uummannaq ice stream (UIS) completely deglaciated from the continental shelf between 14.8 ka and 11.0 ka in response to rising air temperatures, increasing JJA solar radiation and sea-level rise, but temporary standstills and the asynchronous retreat history of its feeder zones suggest that topography/bathymetry strongly modulated retreat rates as ice became 'locked' back into the coastal fjord system. Initial reconstructions of behaviour UIS discounted an oceanic role in early deglaciation and favoured retreat from the mid-shelf and inner-shelf prior to the Younger Dryas but both these concepts remain under investigation. In Disko Bugt, Jakobshavn Isbrae deglaciated later than the UIS and remained on the outer shelf during the Younger Dyras stadial (12.8 - 11.7 cal. kyrs BP) only reaching in the inner coast fjords at approximately 10.0 ka. The later deglaciation of the Disko system (despite similar external forcing mechanisms) was controlled by regional topographic/bathymetric contrasts in their respective trough morphologies. This hypothesis is supported by recent model

  4. Diurnal discharge fluctuations and streambed ablation in a supraglacial stream on the Vaughan-Lewis and Gilkey glaciers, Juneau Icefield, Alaska

    SciTech Connect

    Stock, J.W. |; Pinchak, A.C. |

    1995-12-31

    The study reported here focuses on the dynamics of two supraglacial streams on the Juneau Icefield in southeast Alaska. Data on streambed ablation (melting) rates, stream discharge, radiation, and air temperature and humidity were collected in August 1990 and 1991. Radiation had the greatest effect on stream discharge. Daily peak discharges occurred only 30 minutes after peak radiation, but two hours after peak temperature. Factors influencing variation in discharge of the streams were velocity, stream depth, and stream width, in decreasing order of importance. Streambed ablation due to radiation was greater than glacier surface ablation due to radiation. Streambed ablation due to frictional heating was very small.

  5. Role of monitoring in stream restoration

    EPA Science Inventory

    Hydrology and dissolved organic carbon availability dictate nitrate dynamics in urban streams. So to improve N uptake, restore streams to: • Slow down stream flow • Add organic carbon • Reconnect floodplain hydrology and riparian zones

  6. Electronic Eye: Streaming Video On-Demand.

    ERIC Educational Resources Information Center

    Meulen, Kathleen

    2002-01-01

    Discusses the use of on-demand streaming video in school libraries. Explains how streaming works, considers advantages and technical issues, and describes products from three companies that are pioneering streaming in the educational video market. (LRW)

  7. Ooishi's Observation: Viewed in the Context of Jet Stream Discovery.

    NASA Astrophysics Data System (ADS)

    Lewis, John M.

    2003-03-01

    Although aircraft encounters with strong westerly winds during World War II provided the stimulus for postwar research on the jet stream, Wasaburo Ooishi observed these winds in the 1920s. Ooishi's work is reviewed in the context of earlier work in upperair observation and postwar work on the jet stream. An effort is made to reconstruct Ooishi's path to the directorship of Japan's first upper-air observatory by reliance on historical studies and memoirs from the Central Meteorological Observatory.Archival records from Japan's Aerological Observatory have been used to document Ooishi's upperair observations. The first official report from the observatory (written in 1926 and in the auxiliary language of Esperanto) assumes a central role in the study. In this report, data are stratified by season and used to produce the mean seasonal wind profiles. The profile for winter gives the first known evidence of the persistent strong westerlies over Japan that would later become known as the jet stream.

  8. Student Models for Prior Knowledge Estimation

    ERIC Educational Resources Information Center

    Nižnan, Juraj; Pelánek, Radek; Rihák, Jirí

    2015-01-01

    Intelligent behavior of adaptive educational systems is based on student models. Most research in student modeling focuses on student learning (acquisition of skills). We focus on prior knowledge, which gets much less attention in modeling and yet can be highly varied and have important consequences for the use of educational systems. We describe…

  9. Recognition of Prior Learning: The Participants' Perspective

    ERIC Educational Resources Information Center

    Miguel, Marta C.; Ornelas, José H.; Maroco, João P.

    2016-01-01

    The current narrative on lifelong learning goes beyond formal education and training, including learning at work, in the family and in the community. Recognition of prior learning is a process of evaluation of those skills and knowledge acquired through life experience, allowing them to be formally recognized by the qualification systems. It is a…

  10. 7 CFR 2500.049 - Prior approvals.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 15 2012-01-01 2012-01-01 false Prior approvals. 2500.049 Section 2500.049 Agriculture Regulations of the Department of Agriculture (Continued) OFFICE OF ADVOCACY AND OUTREACH, DEPARTMENT OF AGRICULTURE OAO FEDERAL FINANCIAL ASSISTANCE PROGRAMS-GENERAL AWARD ADMINISTRATIVE...

  11. 7 CFR 2500.049 - Prior approvals.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Prior approvals. 2500.049 Section 2500.049 Agriculture Regulations of the Department of Agriculture (Continued) OFFICE OF ADVOCACY AND OUTREACH, DEPARTMENT OF AGRICULTURE OAO FEDERAL FINANCIAL ASSISTANCE PROGRAMS-GENERAL AWARD ADMINISTRATIVE...

  12. 7 CFR 2500.049 - Prior approvals.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Prior approvals. 2500.049 Section 2500.049 Agriculture Regulations of the Department of Agriculture (Continued) OFFICE OF ADVOCACY AND OUTREACH, DEPARTMENT OF AGRICULTURE OAO FEDERAL FINANCIAL ASSISTANCE PROGRAMS-GENERAL AWARD ADMINISTRATIVE...

  13. Understanding the Complexities of Prior Knowledge

    ERIC Educational Resources Information Center

    Soiferman, L. Karen

    2014-01-01

    The purpose of the study was to gain an understanding of the kinds of prior knowledge students bring with them from high school as it relates to the conventions of writing that they are expected to follow in ARTS 1110 Introduction to University. The research questions were "Can first-year students taking the Arts 1110 Introduction to…

  14. 22 CFR 129.8 - Prior notification.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Prior notification. 129.8 Section 129.8 Foreign Relations DEPARTMENT OF STATE INTERNATIONAL TRAFFIC IN ARMS REGULATIONS REGISTRATION AND LICENSING OF.... (c) The procedures outlined in § 126.8(c) through (g) are equally applicable with respect to...

  15. Prior Learning Assessment: Outcomes and Characteristics.

    ERIC Educational Resources Information Center

    White, Barbara

    1995-01-01

    Describes the Ontario college system's Prior Learning Assessment program for adult learners, focusing on outcomes and characteristics of students completing the process at Seneca College from April 1994 to February 1995. Indicates that of 77 participants, 46 were female, the mean age was 31, and 81% passed the process successfully. (BCY)

  16. Tuning Your Priors to the World

    PubMed Central

    Feldman, Jacob

    2013-01-01

    The idea that perceptual and cognitive systems must incorporate knowledge about the structure of the environment has become a central dogma of cognitive theory. In a Bayesian context, this idea is often realized in terms of “tuning the prior”—widely assumed to mean adjusting prior probabilities so that they match the frequencies of events in the world. This kind of “ecological” tuning has often been held up as an ideal of inference, in fact defining an “ideal observer.” But widespread as this viewpoint is, it directly contradicts Bayesian philosophy of probability, which views probabilities as degrees of belief rather than relative frequencies, and explicitly denies that they are objective characteristics of the world. Moreover, tuning the prior to observed environmental frequencies is subject to overfitting, meaning in this context overtuning to the environment, which leads (ironically) to poor performance in future encounters with the same environment. Whenever there is uncertainty about the environment—which there almost always is—an agent's prior should be biased away from ecological relative frequencies and toward simpler and more entropic priors. PMID:23335572

  17. Objective prior distribution of climate sensitivity

    NASA Astrophysics Data System (ADS)

    Pueyo, S.

    2012-04-01

    The problems posed by the choice of prior distribution constitute one of the most fundamental obstacles to assign probabilities to the possible values of climate sensitivity S. The prior is the probability distribution that we assume before introducing data. In the literature about climate sensitivity, the most frequently used prior is the uniform. On first inspection, this distribution would seem to represent absence of information, but, as is well known, this assumption leads to paradoxes. This observation has led to the widespread belief that priors are inherently subjective and should be decided by expert elicitation, even though this amounts to questioning the objective value of scientific results. In general, the climate science community is unaware of the "objective Bayesian" literature, which seeks objective criteria to determine non-informative prior distributions (or reference priors). In a recent paper (Pueyo 2011) I applied an objective Bayesian approach to climate sensitivity. I described three lines of evidence indicating that the distribution that really represents absence of information about S is log-uniform, i.e. it consists of a uniform distribution of log(S) instead of S: • In the case of S, only the log-uniform distribution satisfies Jaynes' invariant groups criterion, i.e. this distribution does not change when modifying assumptions that are not explicitly included in the enunciate of the problem (I only included the definition of S). • In terms of information theory, information about S can be identified with mutual information between changes in radiative forcing and in temperature. Absence of mutual information between these variables implies a log-uniform distribution of S. • The frequency distribution of sets of parameters formally comparable to climate sensitivity is approximately log-uniform for a broad range of values. A log-uniform distribution of S is intermediate between a uniform distribution of S and a uniform distribution

  18. The Stream-Catchment (StreamCat) Dataset

    EPA Science Inventory

    Stream environments reflect, in part, the hydrologic integration of upstream landscapes. Characterizing upstream landscape features is critical for effectively understanding, managing, and conserving riverine ecosystems. However, watershed delineation is a major challenge if hund...

  19. Prior voluntary wheel running attenuates neuropathic pain.

    PubMed

    Grace, Peter M; Fabisiak, Timothy J; Green-Fulgham, Suzanne M; Anderson, Nathan D; Strand, Keith A; Kwilasz, Andrew J; Galer, Erika L; Walker, Frederick Rohan; Greenwood, Benjamin N; Maier, Steven F; Fleshner, Monika; Watkins, Linda R

    2016-09-01

    Exercise is known to exert a systemic anti-inflammatory influence, but whether its effects are sufficient to protect against subsequent neuropathic pain is underinvestigated. We report that 6 weeks of voluntary wheel running terminating before chronic constriction injury (CCI) prevented the full development of allodynia for the ∼3-month duration of the injury. Neuroimmune signaling was assessed at 3 and 14 days after CCI. Prior exercise normalized ipsilateral dorsal spinal cord expression of neuroexcitatory interleukin (IL)-1β production and the attendant glutamate transporter GLT-1 decrease, as well as expression of the disinhibitory P2X4R-BDNF axis. The expression of the macrophage marker Iba1 and the chemokine CCL2 (MCP-1), and a neuronal injury marker (activating transcription factor 3), was attenuated by prior running in the ipsilateral lumbar dorsal root ganglia. Prior exercise suppressed macrophage infiltration and/or injury site proliferation, given decreased presence of macrophage markers Iba1, iNOS (M1), and Arg-1 (M2; expression was time dependent). Chronic constriction injury-driven increases in serum proinflammatory chemokines were suppressed by prior running, whereas IL-10 was increased. Peripheral blood mononuclear cells were also stimulated with lipopolysaccharide ex vivo, wherein CCI-induced increases in IL-1β, nitrite, and IL-10 were suppressed by prior exercise. Last, unrestricted voluntary wheel running, beginning either the day of, or 2 weeks after, CCI, progressively reversed neuropathic pain. This study is the first to investigate the behavioral and neuroimmune consequences of regular exercise terminating before nerve injury. This study suggests that chronic pain should be considered a component of "the diseasome of physical inactivity," and that an active lifestyle may prevent neuropathic pain. PMID:27355182

  20. Prior voluntary wheel running attenuates neuropathic pain.

    PubMed

    Grace, Peter M; Fabisiak, Timothy J; Green-Fulgham, Suzanne M; Anderson, Nathan D; Strand, Keith A; Kwilasz, Andrew J; Galer, Erika L; Walker, Frederick Rohan; Greenwood, Benjamin N; Maier, Steven F; Fleshner, Monika; Watkins, Linda R

    2016-09-01

    Exercise is known to exert a systemic anti-inflammatory influence, but whether its effects are sufficient to protect against subsequent neuropathic pain is underinvestigated. We report that 6 weeks of voluntary wheel running terminating before chronic constriction injury (CCI) prevented the full development of allodynia for the ∼3-month duration of the injury. Neuroimmune signaling was assessed at 3 and 14 days after CCI. Prior exercise normalized ipsilateral dorsal spinal cord expression of neuroexcitatory interleukin (IL)-1β production and the attendant glutamate transporter GLT-1 decrease, as well as expression of the disinhibitory P2X4R-BDNF axis. The expression of the macrophage marker Iba1 and the chemokine CCL2 (MCP-1), and a neuronal injury marker (activating transcription factor 3), was attenuated by prior running in the ipsilateral lumbar dorsal root ganglia. Prior exercise suppressed macrophage infiltration and/or injury site proliferation, given decreased presence of macrophage markers Iba1, iNOS (M1), and Arg-1 (M2; expression was time dependent). Chronic constriction injury-driven increases in serum proinflammatory chemokines were suppressed by prior running, whereas IL-10 was increased. Peripheral blood mononuclear cells were also stimulated with lipopolysaccharide ex vivo, wherein CCI-induced increases in IL-1β, nitrite, and IL-10 were suppressed by prior exercise. Last, unrestricted voluntary wheel running, beginning either the day of, or 2 weeks after, CCI, progressively reversed neuropathic pain. This study is the first to investigate the behavioral and neuroimmune consequences of regular exercise terminating before nerve injury. This study suggests that chronic pain should be considered a component of "the diseasome of physical inactivity," and that an active lifestyle may prevent neuropathic pain.

  1. Solute-specific scaling of inorganic nitrogen and phosphorus uptake in streams

    NASA Astrophysics Data System (ADS)

    Hall, R. O., Jr.; Baker, M. A.; Rosi-Marshall, E. J.; Tank, J. L.; Newbold, J. D.

    2013-11-01

    Stream ecosystem processes such as nutrient cycling may vary with stream position in the network. Using a scaling approach, we examined the relationship between stream size and nutrient uptake length, which represents the mean distance that a dissolved solute travels prior to removal from the water column. Ammonium (NH4+) uptake length increased proportionally with stream size measured as specific discharge (discharge/stream width) with a scaling exponent = 1.01. In contrast, uptake lengths for nitrate (NO3-) and soluble reactive phosphorus (SRP) increased more rapidly than increases in specific discharge (scaling exponents = 1.19 for NO3- and 1.35 for SRP). Additionally, the ratio of inorganic nitrogen (N) uptake length to SRP uptake length declined with stream size; there was relatively lower demand for SRP compared to N as stream size increased. Finally, we related the scaling of uptake length with specific discharge to that of stream length using Hack's law and downstream hydraulic geometry. Ammonium uptake length increased less than proportionally with distance from the headwaters, suggesting a strong role for larger streams and rivers in regulating nutrient transport.

  2. Redox reaction rates in shallow aquifers: Implications for nitrate transport in groundwater and streams

    USGS Publications Warehouse

    Tesoriero, Anthony J.

    2012-01-01

    Groundwater age and water chemistry data along flow paths from recharge areas to streams were used to evaluate the trends and transformations of agricultural chemicals. Results from this analysis indicate that median nitrate recharge concentrations in these agricultural areas have increased markedly over the last 50 years from 4 mg N/L in samples collected prior to 1983 to 7.5 mg N/L in samples collected since 1983. The effect that nitrate accumulation in shallow aquifers will have on drinking water quality and stream ecosystems is dependent on the rate of redox reactions along flow paths and on the age distribution of nitrate discharging to supply wells and streams.

  3. Spectral priors improve near-infrared diffuse tomography more than spatial priors

    NASA Astrophysics Data System (ADS)

    Brooksby, Ben; Srinivasan, Subhadra; Jiang, Shudong; Dehghani, Hamid; Pogue, Brian W.; Paulsen, Keith D.; Weaver, John; Kogel, Christine; Poplack, Steven P.

    2005-08-01

    We compare the benefits of spatial and spectral priors in near-infrared diffuse tomography image reconstruction. Although previous studies that incorporated anatomical spatial priors have shown improvement in algorithm convergence and resolution, our results indicate that functional parameter quantification by this approach can be suboptimal. The incorporation of a priori spectral information significantly improves the accuracy observed in recovered images. Specifically, phantom results show that the maximum total hemoglobin concentration ([HbT]) in a region of heterogeneity reached 91% of the true value compared to 63% using spatial priors. The combination of both priors produced results accurate to 98% of the true [HbT]. When both spatial and spectral priors were applied in a healthy volunteer, glandular tissue showed a higher [HbT], water fraction, and scattering power compared to adipose tissue.

  4. CONTROL OF AROMATIC WASTE AIR STREAMS BY SOIL BIOREACTORS

    EPA Science Inventory

    Three soils were examined for the ability to degrade hydrocarbon vapors of benzene, toluene, ethylbenzene, and o-xylene (BTEX). Each of these compounds are major aromatic constituents of gasolines. The soils examined were Rubicon Sand from Traverse City, Michigan, Durant Loam fro...

  5. Corrections on the Thermometer Reading in an Air Stream

    NASA Technical Reports Server (NTRS)

    Van Der Maas, H J; Wynia, S

    1940-01-01

    A method is described for checking a correction formula, based partly on theoretical considerations, for adiabatic compression and friction in flight tests and determining the value of the constant. It is necessary to apply a threefold correction to each thermometer reading. They are a correction for adiabatic compression, friction and for time lag.

  6. Removal of gasoline vapors from air streams by biofiltration

    SciTech Connect

    Apel, W.A.; Kant, W.D.; Colwell, F.S.; Singleton, B.; Lee, B.D.; Andrews, G.F.; Espinosa, A.M.; Johnson, E.G.

    1993-03-01

    Research was performed to develop a biofilter for the biodegradation of gasoline vapors. The overall goal of this effort was to provide information necessary for the design, construction, and operation of a commercial gasoline vapor biofilter. Experimental results indicated that relatively high amounts of gasoline vapor adsorption occur during initial exposure of the biofilter bed medium to gasoline vapors. Biological removal occurs over a 22 to 40[degrees]C temperature range with removal being completely inhibited at 54[degrees]C. The addition of fertilizer to the relatively fresh bed medium used did not increase the rates of gasoline removal in short term experiments. Microbiological analyses indicated that high levels of gasoline degrading microbes are naturally present in the bed medium and that additional inoculation with hydrocarbon degrading cultures does not appreciably increase gasoline removal rates. At lower gasoline concentrations, the vapor removal rates were considerably lower than those at higher gasoline concentrations. This implies that system designs facilitating gasoline transport to the micro-organisms could substantially increase gasoline removal rates at lower gasoline vapor concentrations. Test results from a field scale prototype biofiltration system showed volumetric productivity (i.e., average rate of gasoline degradation per unit bed volume) values that were consistent with those obtained with laboratory column biofilters at similar inlet gasoline concentrations. In addition, total benzene, toluene, ethyl-benzene, and xylene (BTEX) removal over the operating conditions employed was 50 to 55%. Removal of benzene was approximately 10 to 15% and removal of the other members of the BTEX group was much higher, typically >80%.

  7. Removal of gasoline vapors from air streams by biofiltration

    SciTech Connect

    Apel, W.A.; Kant, W.D.; Colwell, F.S.; Singleton, B.; Lee, B.D.; Andrews, G.F.; Espinosa, A.M.; Johnson, E.G.

    1993-03-01

    Research was performed to develop a biofilter for the biodegradation of gasoline vapors. The overall goal of this effort was to provide information necessary for the design, construction, and operation of a commercial gasoline vapor biofilter. Experimental results indicated that relatively high amounts of gasoline vapor adsorption occur during initial exposure of the biofilter bed medium to gasoline vapors. Biological removal occurs over a 22 to 40{degrees}C temperature range with removal being completely inhibited at 54{degrees}C. The addition of fertilizer to the relatively fresh bed medium used did not increase the rates of gasoline removal in short term experiments. Microbiological analyses indicated that high levels of gasoline degrading microbes are naturally present in the bed medium and that additional inoculation with hydrocarbon degrading cultures does not appreciably increase gasoline removal rates. At lower gasoline concentrations, the vapor removal rates were considerably lower than those at higher gasoline concentrations. This implies that system designs facilitating gasoline transport to the micro-organisms could substantially increase gasoline removal rates at lower gasoline vapor concentrations. Test results from a field scale prototype biofiltration system showed volumetric productivity (i.e., average rate of gasoline degradation per unit bed volume) values that were consistent with those obtained with laboratory column biofilters at similar inlet gasoline concentrations. In addition, total benzene, toluene, ethyl-benzene, and xylene (BTEX) removal over the operating conditions employed was 50 to 55%. Removal of benzene was approximately 10 to 15% and removal of the other members of the BTEX group was much higher, typically >80%.

  8. Streaming in English Primary Schools

    ERIC Educational Resources Information Center

    Acland, H.

    1973-01-01

    This paper seeks to extend our knowledge of ability grouping through the reanalysis of two sets of survey data, the Plowden survey (Peaker, 1967) and the NFER streaming survey (Barker Lunn, 1970). (Editor)

  9. FireHose Streaming Benchmarks

    2015-01-27

    The FireHose Streaming Benchmarks are a suite of stream-processing benchmarks defined to enable comparison of streaming software and hardware, both quantitatively vis-a-vis the rate at which they can process data, and qualitatively by judging the effort involved to implement and run the benchmarks. Each benchmark has two parts. The first is a generator which produces and outputs datums at a high rate in a specific format. The second is an analytic which reads the streammore » of datums and is required to perform a well-defined calculation on the collection of datums, typically to find anomalous datums that have been created in the stream by the generator. The FireHose suite provides code for the generators, sample code for the analytics (which users are free to re-implement in their own custom frameworks), and a precise definition of each benchmark calculation.« less

  10. MODELING PLUMES IN SMALL STREAMS

    EPA Science Inventory

    Pesticides accumulate on land surfaces from agricultural, commercial, and domestic application, and wash into streams and rivers during dry and wet weather. Flood water retention basins or structures often collect this contaminated runoff, providing intermediate storage and limit...

  11. ATLAS Live: Collaborative Information Streams

    NASA Astrophysics Data System (ADS)

    Goldfarb, Steven; ATLAS Collaboration

    2011-12-01

    I report on a pilot project launched in 2010 focusing on facilitating communication and information exchange within the ATLAS Collaboration, through the combination of digital signage software and webcasting. The project, called ATLAS Live, implements video streams of information, ranging from detailed detector and data status to educational and outreach material. The content, including text, images, video and audio, is collected, visualised and scheduled using digital signage software. The system is robust and flexible, utilizing scripts to input data from remote sources, such as the CERN Document Server, Indico, or any available URL, and to integrate these sources into professional-quality streams, including text scrolling, transition effects, inter and intra-screen divisibility. Information is published via the encoding and webcasting of standard video streams, viewable on all common platforms, using a web browser or other common video tool. Authorisation is enforced at the level of the streaming and at the web portals, using the CERN SSO system.

  12. Cellular Subcompartments through Cytoplasmic Streaming.

    PubMed

    Pieuchot, Laurent; Lai, Julian; Loh, Rachel Ann; Leong, Fong Yew; Chiam, Keng-Hwee; Stajich, Jason; Jedd, Gregory

    2015-08-24

    Cytoplasmic streaming occurs in diverse cell types, where it generally serves a transport function. Here, we examine streaming in multicellular fungal hyphae and identify an additional function wherein regimented streaming forms distinct cytoplasmic subcompartments. In the hypha, cytoplasm flows directionally from cell to cell through septal pores. Using live-cell imaging and computer simulations, we identify a flow pattern that produces vortices (eddies) on the upstream side of the septum. Nuclei can be immobilized in these microfluidic eddies, where they form multinucleate aggregates and accumulate foci of the HDA-2 histone deacetylase-associated factor, SPA-19. Pores experiencing flow degenerate in the absence of SPA-19, suggesting that eddy-trapped nuclei function to reinforce the septum. Together, our data show that eddies comprise a subcellular niche favoring nuclear differentiation and that subcompartments can be self-organized as a consequence of regimented cytoplasmic streaming.

  13. Acoustic streaming flows and sample rotation control

    NASA Astrophysics Data System (ADS)

    Trinh, Eugene

    1998-11-01

    Levitated drops in a gas can be driven into rotation by altering their surrounding convective environment. When these drops are placed in an acoustic resonant chamber, the symmetry characteristics of the steady streaming flows in the vicinity of the drops determine the rotational motion of the freely suspended fluid particles. Using ultrasonic standing waves around 22 kHz and millimeter-size electrostatically levitated drops, we have investigated the correlation between the convective flow characteristics and their rotational behavior. The results show that accurate control of the drop rotation axis and rate can be obtained by carefully modifying the symmetry characteristics of the chamber, and that the dominant mechanism for rotation drive is the drag exerted by the air flow over the drop surface. In addition, we found that the rotational acceleration depends on the drop viscosity, suggesting that this torque is initially strongly influenced by differential flows within the drop itself. [Work sponsored by NASA].

  14. RELATIONSIPS BETWEEN AQUATIC INVERTEBRATE ASSEMBLAGES AND REACH AND LANDSCAPE ATTRIBUTES ON WADEABLE, WILLAMETTE VALLEY STREAMS IN AGRICULTURAL WATERSHEDS

    EPA Science Inventory

    In summer 1997, we sampled reaches in 24 wadeable, Willamette Valley ecoregion streams draining agriculturally-infiuenced watersheds. Within these reaches, physical habitat, water chemistry, aquatic invertebrate and fish data and samples were collected. Low-level air photos were ...

  15. Combustion of dense streams of coal particles. Quarterly progress report No. 12, May 29, 1993--August 28, 1993

    SciTech Connect

    Annamalai, K.

    1993-09-20

    Research continued on coal stream combustion. This report presents the results obtained from the gasification efficiency experiments by varying the (i) air fuel ratio of the coal cloud (ii) reaction zone height (residence time) and (iii) oxygen concentration. A brief discussion on the divergence of coal stream is presented.

  16. Combustion chamber and thermal vapor stream producing apparatus and method

    DOEpatents

    Sperry, John S.; Krajicek, Richard W.; Cradeur, Robert R.

    1978-01-01

    A new and improved method and apparatus for burning a hydrocarbon fuel for producing a high pressure thermal vapor stream comprising steam and combustion gases for injecting into a subterranean formation for the recovery of liquefiable minerals therefrom, wherein a high pressure combustion chamber having multiple refractory lined combustion zones of varying diameters is provided for burning a hydrocarbon fuel and pressurized air in predetermined ratios injected into the chamber for producing hot combustion gases essentially free of oxidizing components and solid carbonaceous particles. The combustion zones are formed by zones of increasing diameters up a final zone of decreasing diameter to provide expansion zones which cause turbulence through controlled thorough mixing of the air and fuel to facilitate complete combustion. The high pressure air and fuel is injected into the first of the multiple zones where ignition occurs with a portion of the air injected at or near the point of ignition to further provide turbulence and more complete combustion.

  17. Distillation plus membrane processing of gas streams

    SciTech Connect

    Waldo, R.A.; Burkinshaw, J.R.

    1990-06-26

    This patent describes a process for separating components of a feed gas stream comprising carbon dioxide, hydrogen sulfide, nitrogen, methane, and higher molecular weight hydrocarbons to form a carbon dioxide-rich stream and a methane-rich stream. It comprises: passing the feed gas stream to a first fractional distillation column; withdrawing a first overhead stream from the first fractional distillation column; withdrawing a first bottoms stream from the first fractional distillation column; passing the first overhead stream to a second fractional distillation column; withdrawing a second overhead stream wherein the second overhead stream is withdrawn from the second fractional distillation column; withdrawing a second bottoms stream wherein the second bottoms stream is withdrawn from the second fractional distillation column; passing the second overhead stream to a membrane separation unit; withdrawing a residual gas stream from the membrane separation unit to form the methane-rich stream; and withdrawing a residual gas stream from the membrane separation unit to form a recycle stream having a substantially increased concentration of carbon dioxide relative to the concentration of carbon dioxide in the second overhead stream.

  18. Image Reconstruction Using Analysis Model Prior.

    PubMed

    Han, Yu; Du, Huiqian; Lam, Fan; Mei, Wenbo; Fang, Liping

    2016-01-01

    The analysis model has been previously exploited as an alternative to the classical sparse synthesis model for designing image reconstruction methods. Applying a suitable analysis operator on the image of interest yields a cosparse outcome which enables us to reconstruct the image from undersampled data. In this work, we introduce additional prior in the analysis context and theoretically study the uniqueness issues in terms of analysis operators in general position and the specific 2D finite difference operator. We establish bounds on the minimum measurement numbers which are lower than those in cases without using analysis model prior. Based on the idea of iterative cosupport detection (ICD), we develop a novel image reconstruction model and an effective algorithm, achieving significantly better reconstruction performance. Simulation results on synthetic and practical magnetic resonance (MR) images are also shown to illustrate our theoretical claims. PMID:27379171

  19. Knowledge Modeling in Prior Art Search

    NASA Astrophysics Data System (ADS)

    Graf, Erik; Frommholz, Ingo; Lalmas, Mounia; van Rijsbergen, Keith

    This study explores the benefits of integrating knowledge representations in prior art patent retrieval. Key to the introduced approach is the utilization of human judgment available in the form of classifications assigned to patent documents. The paper first outlines in detail how a methodology for the extraction of knowledge from such an hierarchical classification system can be established. Further potential ways of integrating this knowledge with existing Information Retrieval paradigms in a scalable and flexible manner are investigated. Finally based on these integration strategies the effectiveness in terms of recall and precision is evaluated in the context of a prior art search task for European patents. As a result of this evaluation it can be established that in general the proposed knowledge expansion techniques are particularly beneficial to recall and, with respect to optimizing field retrieval settings, further result in significant precision gains.

  20. Reference priors for high energy physics

    SciTech Connect

    Demortier, Luc; Jain, Supriya; Prosper, Harrison B.

    2010-08-01

    Bayesian inferences in high energy physics often use uniform prior distributions for parameters about which little or no information is available before data are collected. The resulting posterior distributions are therefore sensitive to the choice of parametrization for the problem and may even be improper if this choice is not carefully considered. Here we describe an extensively tested methodology, known as reference analysis, which allows one to construct parametrization-invariant priors that embody the notion of minimal informativeness in a mathematically well-defined sense. We apply this methodology to general cross section measurements and show that it yields sensible results. A recent measurement of the single-top quark cross section illustrates the relevant techniques in a realistic situation.

  1. Image Reconstruction Using Analysis Model Prior

    PubMed Central

    Han, Yu; Du, Huiqian; Lam, Fan; Mei, Wenbo; Fang, Liping

    2016-01-01

    The analysis model has been previously exploited as an alternative to the classical sparse synthesis model for designing image reconstruction methods. Applying a suitable analysis operator on the image of interest yields a cosparse outcome which enables us to reconstruct the image from undersampled data. In this work, we introduce additional prior in the analysis context and theoretically study the uniqueness issues in terms of analysis operators in general position and the specific 2D finite difference operator. We establish bounds on the minimum measurement numbers which are lower than those in cases without using analysis model prior. Based on the idea of iterative cosupport detection (ICD), we develop a novel image reconstruction model and an effective algorithm, achieving significantly better reconstruction performance. Simulation results on synthetic and practical magnetic resonance (MR) images are also shown to illustrate our theoretical claims. PMID:27379171

  2. The Northeast Stream Quality Assessment

    USGS Publications Warehouse

    Van Metre, Peter C.; Riva-Murray, Karen; Coles, James F.

    2016-04-22

    In 2016, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) is assessing stream quality in the northeastern United States. The goal of the Northeast Stream Quality Assessment (NESQA) is to assess the quality of streams in the region by characterizing multiple water-quality factors that are stressors to aquatic life and evaluating the relation between these stressors and biological communities. The focus of NESQA in 2016 will be on the effects of urbanization and agriculture on stream quality in all or parts of eight states: Connecticut, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont.Findings will provide the public and policymakers with information about the most critical factors affecting stream quality, thus providing insights about possible approaches to protect the health of streams in the region. The NESQA study will be the fourth regional study conducted as part of NAWQA and will be of similar design and scope to the first three, in the Midwest in 2013, the Southeast in 2014, and the Pacific Northwest in 2015 (http://txpub.usgs.gov/RSQA/).

  3. Transformational Learning through Prior Learning Assessment

    ERIC Educational Resources Information Center

    Stevens, Karen; Gerber, Dan; Hendra, Rick

    2010-01-01

    Upon graduation from University Without Walls (UWW), Robin said, "During first semester you told us that if we allowed it to, this experience [writing a prior learning portfolio] would change us. I was so angry with you for saying that because I liked who I was and didn't want to change. But you were right. And I'm glad." For the past 39 years the…

  4. Diversity priors for learning early visual features.

    PubMed

    Xiong, Hanchen; Rodríguez-Sánchez, Antonio J; Szedmak, Sandor; Piater, Justus

    2015-01-01

    This paper investigates how utilizing diversity priors can discover early visual features that resemble their biological counterparts. The study is mainly motivated by the sparsity and selectivity of activations of visual neurons in area V1. Most previous work on computational modeling emphasizes selectivity or sparsity independently. However, we argue that selectivity and sparsity are just two epiphenomena of the diversity of receptive fields, which has been rarely exploited in learning. In this paper, to verify our hypothesis, restricted Boltzmann machines (RBMs) are employed to learn early visual features by modeling the statistics of natural images. Considering RBMs as neural networks, the receptive fields of neurons are formed by the inter-weights between hidden and visible nodes. Due to the conditional independence in RBMs, there is no mechanism to coordinate the activations of individual neurons or the whole population. A diversity prior is introduced in this paper for training RBMs. We find that the diversity prior indeed can assure simultaneously sparsity and selectivity of neuron activations. The learned receptive fields yield a high degree of biological similarity in comparison to physiological data. Also, corresponding visual features display a good generative capability in image reconstruction. PMID:26321941

  5. Entropic Priors and Bayesian Model Selection

    NASA Astrophysics Data System (ADS)

    Brewer, Brendon J.; Francis, Matthew J.

    2009-12-01

    We demonstrate that the principle of maximum relative entropy (ME), used judiciously, can ease the specification of priors in model selection problems. The resulting effect is that models that make sharp predictions are disfavoured, weakening the usual Bayesian ``Occam's Razor.'' This is illustrated with a simple example involving what Jaynes called a ``sure thing'' hypothesis. Jaynes' resolution of the situation involved introducing a large number of alternative ``sure thing'' hypotheses that were possible before we observed the data. However, in more complex situations, it may not be possible to explicitly enumerate large numbers of alternatives. The entropic priors formalism produces the desired result without modifying the hypothesis space or requiring explicit enumeration of alternatives; all that is required is a good model for the prior predictive distribution for the data. This idea is illustrated with a simple rigged-lottery example, and we outline how this idea may help to resolve a recent debate amongst cosmologists: is dark energy a cosmological constant, or has it evolved with time in some way? And how shall we decide, when the data are in?

  6. Air resources

    SciTech Connect

    1995-10-01

    This section describes the ambient (surrounding) air quality of the TVA region, discusses TVA emission contributions to ambient air quality, and identifies air quality impacts to human health and welfare. Volume 2 Technical Document 2, Environmental Consequences, describes how changes in TVA emissions could affect regional air quality, human health, environmental resources, and materials. The primary region of the affected environment is broadly defined as the state of Tennessee, as well as southern Kentucky, western Virginia, southern West Virginia, western North Carolina, and northern Georgia, Alabama, and Mississippi. This area represents the watershed of the Tennessee River and the 201 counties of the greater TVA service area. Emissions from outside the Tennessee Valley region contribute to air quality in the Valley. Also, TVA emissions are transported outside the Valley and have some impact on air quality beyond the primary study area. Although the study area experiences a number of air quality problems, overall air quality is good.

  7. Air-cleaning apparatus

    SciTech Connect

    Howard, A.G.

    1981-08-18

    An air-cleaning, heat-exchange apparatus includes a main housing portion connected by means of an air inlet fan to the kitchen exhaust stack of a restaurant. The apparatus includes a plurality of heat exchangers through which a heat-absorptive fluid is circulated, simultaneously, by means of a suitable fluid pump. These heat exchangers absorb heat from the hot exhaust gas, out of the exhaust stack of the restaurant, which flows over and through these heat exchangers and transfers this heat to the circulating fluid which communicates with remote heat exchangers. These remote heat exchangers further transfer this heat to a stream of air, such as that from a cold-air return duct for supplementing the conventional heating system of the restaurant. Due to the fact that such hot exhaust gas is heavily grease laden , grease will be deposited on virtually all internal surfaces of the apparatus which this exhaust gas contacts. Consequently, means are provided for spraying these contacted internal surfaces , as well as the hot exhaust gas itself, with a detergent solution in which the grease is soluble, thereby removing grease buildup from these internal surfaces.

  8. Air Pollution.

    ERIC Educational Resources Information Center

    Gilpin, Alan

    A summary of one of our most pressing environmental problems, air pollution, is offered in this book by the Director of Air Pollution Control for the Queensland (Australia) State Government. Discussion of the subject is not restricted to Queensland or Australian problems and policies, however, but includes analysis of air pollution the world over.…

  9. Unique Challenges to (Federal) Enterprise Streaming

    NASA Technical Reports Server (NTRS)

    Walls, Bryan

    2006-01-01

    Enterprise streaming has different parameters than consumer Streaming. The government enterprise has some differences on top of that. I'd like to highlight some issues shared by the Federal government as a whole, with a closer look at streaming within NASA. Then we'll look at NASA's strategy for streaming.

  10. Jet stream related observations by MST radars

    NASA Technical Reports Server (NTRS)

    Gage, K. S.

    1983-01-01

    An overview of the jet stream and its observation by MST radar is presented. The climatology and synoptic and mesoscale structure of jet streams is briefly reviewed. MST radar observations of jet stream winds, and associated waves and turbulence are then considered. The possibility of using a network of ST radars to track jet stream winds in near real time is explored.

  11. THE DYNAMICS OF STAR STREAM GAPS

    SciTech Connect

    Carlberg, R. G.

    2013-10-01

    A massive object crossing a narrow stream of stars orbiting in the halo of the galaxy induces velocity changes both along and transverse to the stream that can lead to the development of a visible gap. For a stream narrow relative to its orbital radius, the stream crossing time is sufficiently short that the impact approximation can be used to derive the changes in angular momenta and radial actions along the star stream. The epicyclic approximation is used to calculate the evolution of the density of the stream as it orbits around in a galactic potential. Analytic expressions are available for a point mass, however, the general expressions are easily numerically evaluated for perturbing objects with arbitrary density profiles. With a simple allowance for the velocity dispersion of the stream, moderately warm streams can be modeled. The predicted evolution agrees well with the outcomes of simulations of stellar streams for streams with widths up to 1% of the orbital radius of the stream. The angular momentum distribution within the stream shears out gaps with time, further reducing the visibility of streams, although the size of the shear effect requires more detailed simulations that account for the creation of the stream. An illustrative model indicates that shear will set a lower limit of a few times the stream width for the length of gaps that persist. In general, the equations are useful for dynamical insights into the development of stream gaps and their measurement.

  12. Stream-aquifer interactions in the Straight River area, Becker and Hubbard counties, Minnesota

    USGS Publications Warehouse

    Stark, J.R.; Armstrong, David S.; Zwilling, Daniel R.

    1994-01-01

    Daily fluctuations of stream temperature are as great as 15 degrees Celsius during the summer, primarily in response to changes in air temperature. Ground-water discharge to the Straight River decreases stream temperature during the summer. Results of simulations from a stream-temperature model indicate that daily changes in stream temperature are strongly influenced by solar radiation, wind speed, stream depth, and ground-water inflow. Results of simulations from ground-water-flow and stream-temperature models developed for the investigation indicate a significant decrease in ground-water flow could result from ground-water withdrawal at rates similar to those measured during 1988. This reduction in discharge to the stream could result in an increase in stream temperature of 0.5 to 1.5 degrees Celsius. Nitrate concentrations in shallow wells screened at the water table, in some areas, are locally greater than the limit set by the Minnesota Pollution Control Agency. Nitrate concentrations in water from deeper wells and in the stream are low, generally less than 1.0 milligram per liter.

  13. The Midwest Stream Quality Assessment

    USGS Publications Warehouse

    ,

    2012-01-01

    In 2013, the U.S. Geological Survey (USGS) National Water-Quality Assessment Program (NAWQA) and USGS Columbia Environmental Research Center (CERC) will be collaborating with the U.S. Environmental Protection Agency (EPA) National Rivers and Streams Assessment (NRSA) to assess stream quality across the Midwestern United States. The sites selected for this study are a subset of the larger NRSA, implemented by the EPA, States and Tribes to sample flowing waters across the United States (http://water.epa.gov/type/rsl/monitoring/riverssurvey/index.cfm). The goals are to characterize water-quality stressors—contaminants, nutrients, and sediment—and ecological conditions in streams throughout the Midwest and to determine the relative effects of these stressors on aquatic organisms in the streams. Findings will contribute useful information for communities and policymakers by identifying which human and environmental factors are the most critical in controlling stream quality. This collaborative study enhances information provided to the public and policymakers and minimizes costs by leveraging and sharing data gathered under existing programs. In the spring and early summer, NAWQA will sample streams weekly for contaminants, nutrients, and sediment. During the same time period, CERC will test sediment and water samples for toxicity, deploy time-integrating samplers, and measure reproductive effects and biomarkers of contaminant exposure in fish or amphibians. NRSA will sample sites once during the summer to assess ecological and habitat conditions in the streams by collecting data on algal, macroinvertebrate, and fish communities and collecting detailed physical-habitat measurements. Study-team members from all three programs will work in collaboration with USGS Water Science Centers and State agencies on study design, execution of sampling and analysis, and reporting.

  14. Apparatus and method for burning a lean, premixed fuel/air mixture with low NOx emission

    DOEpatents

    Kostiuk, Larry W.; Cheng, Robert K.

    1996-01-01

    An apparatus for enabling a burner to stably burn a lean fuel/air mixture. The burner directs the lean fuel/air mixture in a stream. The apparatus comprises an annular flame stabilizer; and a device for mounting the flame stabilizer in the fuel/air mixture stream. The burner may include a body having an internal bore, in which case, the annular flame stabilizer is shaped to conform to the cross-sectional shape of the bore, is spaced from the bore by a distance greater than about 0.5 mm, and the mounting device mounts the flame stabilizer in the bore. An apparatus for burning a gaseous fuel with low NOx emissions comprises a device for premixing air with the fuel to provide a lean fuel/air mixture; a nozzle having an internal bore through which the lean fuel/air mixture passes in a stream; and a flame stabilizer mounted in the stream of the lean fuel/air mixture. The flame stabilizer may be mounted in the internal bore, in which case, it is shaped and is spaced from the bore as just described. In a method of burning a lean fuel/air mixture, a lean fuel/air mixture is provided, and is directed in a stream; an annular eddy is created in the stream of the lean fuel/air mixture; and the lean fuel/air mixture is ignited at the eddy.

  15. Fuel-cell engine stream conditioning system

    DOEpatents

    DuBose, Ronald Arthur

    2002-01-01

    A stream conditioning system for a fuel cell gas management system or fuel cell engine. The stream conditioning system manages species potential in at least one fuel cell reactant stream. A species transfer device is located in the path of at least one reactant stream of a fuel cell's inlet or outlet, which transfer device conditions that stream to improve the efficiency of the fuel cell. The species transfer device incorporates an exchange media and a sorbent. The fuel cell gas management system can include a cathode loop with the stream conditioning system transferring latent and sensible heat from an exhaust stream to the cathode inlet stream of the fuel cell; an anode humidity retention system for maintaining the total enthalpy of the anode stream exiting the fuel cell related to the total enthalpy of the anode inlet stream; and a cooling water management system having segregated deionized water and cooling water loops interconnected by means of a brazed plate heat exchanger.

  16. Heat Transfer and Hydraulic Flow Resistance for Streams of High Velocity

    NASA Technical Reports Server (NTRS)

    Lelchuk, V. L.

    1943-01-01

    Problems of hydraulic flow resistance and heat transfer for streams with velocities comparable with acoustic have present great importance for various fields of technical science. Especially, they have great importance for the field of heat transfer in designing and constructing boilers.of the "Velox" type. In this article a description of experiments and their results as regards definition of the laws of heat transfer in differential form for high velocity air streams inside smooth tubes are given.

  17. Flow variability and ongoing margin shifts on Bindschadler and MacAyeal Ice Streams, West Antarctica

    NASA Astrophysics Data System (ADS)

    Hulbe, C. L.; Scambos, T. A.; Klinger, M.; Fahnestock, M. A.

    2016-02-01

    Ice streams on the Ross Sea side of the West Antarctic Ice Sheet are known to experience flow variability on hourly, annual, and multicentury time scales. We report here on observations of flow variability at the decade scale on the Bindschadler and MacAyeal Ice Streams (BIS and MacIS). Our analysis makes use of archived ice velocity data and new mappings from composited Landsat 7 and Landsat 8 imagery that together span the interval from 1985 to 2014. Both ice streams speedup and slowdown in a range of about ±5 m a-2 over our various comparison intervals. The rates of change are variable in both time and space, and there is no evidence of external forcing at work across the two streams. Widespread changes are most likely linked to instability in the subglacial till and/or subglacial water flow. Sticky spots near the confluence of the two ice streams are loci for speed changes. These relatively young and slow-flowing features appear to be forcing shifts in margin position near the outlets of both streams. The margin jumps reduce the effective outlet widths of the streams by 20% and 30% on BIS and MacIS, respectively. Those magnitudes are similar to the outlet narrowing experienced by Kamb Ice Stream prior to its stagnation.

  18. Antarctic climate cooling and response of diatoms in glacial meltwater streams

    USGS Publications Warehouse

    Esposito, R.M.M.; Horn, S.L.; McKnight, Diane M.; Cox, M.J.; Grant, M.C.; Spaulding, S.A.; Doran, P.T.; Cozzetto, K.D.

    2006-01-01

    To understand biotic responses to an Antarctic cooling trend diatom samples from glacial meltwater streams in the McMurdo Dry Valleys, the largest ice-free area in Antarctica. Diatoms are abundant in these streams, and 24 of 40 species have only been found in the Antarctic. The percentage of these Antarctic diatom species increased with decreasing annual stream flow and increasing harshness of the stream habitat. The species diversity of assemblages reached a maximum when the Antarctic species accounted for 40-60% of relative diatom abundance. Decreased solar radiation and air-temperatures reduce annual stream flow, raising the dominance of these Antarctic species to levels above 60%. Thus, cooling favors the Antarctic species, and lowers diatom species diversity in this region. Copyright 2006 by the American Geophysical Union.

  19. Recurring Cold Winters over the Gulf Stream and Implications for Northern Hemisphere Ocean Circulation

    NASA Astrophysics Data System (ADS)

    Strey, S. T.

    2015-12-01

    As polar amplification of climate warming continues, the potential for increased blocking patterns in the Northern Hemisphere jet stream in conjunction with Arctic climate change exists. During such blocking events the Gulf Stream may be exposed to repeated Cold Air Outbreak (CAO) events, especially during winter. Hypothesizing, based upon basic physical and thermodynamic properties of seawater, one would expect increased CAO events to lead alteration of key characteristics of the Gulf Stream. As the Gulf Stream is a well-known participant in the Atlantic meridional overturning circulation (AMOC), and the Gulf Stream feeds the North Atlantic Current into the Arctic Ocean, interesting consequences to alterations of this local system into the large-scale general climate circulation are expected. This study uses CESM's POP to examine 30 years of CAO intensive winters alongside 30 years of repeated winter warm events to quantify potential subsequent changes in the AMOC and North Atlantic Arctic Ocean inflow.

  20. Inactive comets within meteoroid streams

    NASA Astrophysics Data System (ADS)

    Kokhirova, Gulchekhra; Babadzhanov, Pulat; Obrubov, Yuri

    2015-08-01

    The modern concepts of formation and evolution of the meteoroid streams originated as a result of disintegration of cometary nuclei are presented. The action of planetary perturbations that defines the orbital evolution of meteoroids is discussed. The main regularities in variations of the orbital elements as well as of the heliocentric distances of ascending and descending nodes are found on the base of calculation of orbital evolution of a sample of NEAs. A dispersion of the orbits is increasing with a time and meteoroid streams in dependence of the type of a parent comet orbit can produce up to eight meteor showers observable at the Earth. It is recognized that some meteoroid streams contain large extinct fragments of cometary nuclei. These fragments have been found among NEAs and should be considered as the constituent parts of meteoroid streams. Consequently, meteoroid streams consist of both small particles and large fireball-producing bodies. This fact supported by the results of investigation of a sample of three asteroid-meteoroid complexes.

  1. Streaming Compression of Hexahedral Meshes

    SciTech Connect

    Isenburg, M; Courbet, C

    2010-02-03

    We describe a method for streaming compression of hexahedral meshes. Given an interleaved stream of vertices and hexahedral our coder incrementally compresses the mesh in the presented order. Our coder is extremely memory efficient when the input stream documents when vertices are referenced for the last time (i.e. when it contains topological finalization tags). Our coder then continuously releases and reuses data structures that no longer contribute to compressing the remainder of the stream. This means in practice that our coder has only a small fraction of the whole mesh in memory at any time. We can therefore compress very large meshes - even meshes that do not file in memory. Compared to traditional, non-streaming approaches that load the entire mesh and globally reorder it during compression, our algorithm trades a less compact compressed representation for significant gains in speed, memory, and I/O efficiency. For example, on the 456k hexahedra 'blade' mesh, our coder is twice as fast and uses 88 times less memory (only 3.1 MB) with the compressed file increasing about 3% in size. We also present the first scheme for predictive compression of properties associated with hexahedral cells.

  2. How do hydrodynamics in the critical zone relate to stream temperature distribution?

    NASA Astrophysics Data System (ADS)

    Isaacson, M. R.; Boutt, D. F.

    2013-12-01

    Rising air temperature and decreasing stream flow trends are predicted to result in corresponding increases in stream temperatures. As a result, the future of ectothermic stream fishes, which rely on seasonal and spatial temperature distributions for growth and survival, could be in jeopardy. Fortunately, contradicting stream temperature trends in forested headwater catchments suggest that non-climatic variables, such as baseflow indices and catchment geologic structure, may have an important confounding influence on the future of stream temperature. Most significantly, the annual variability of groundwater temperature has long been recognized as an important contributor to the advective heat budget of streams. In this study we move beyond the hyporheic zone to investigate the drivers of shallow groundwater temperature variability in the recharge zone of a shallow bedrock/till-mantled headwater catchment. We use isotopic and hydrometric analyses to investigate the potential influence that near surface hydrodynamics have on how air and shallow groundwater temperatures relate to baseflow temperature distributions. We use field studies and numerical analysis to investigate how conductive heat signals in the near surface behave with respect to soil saturation, thermal conductivity, and threshold discharge events. We examine how antecedent moisture conditions in the near-surface impact the thermal conduction of air temperature into shallow water tables, and how that translates to temperature distributions in baseflow. Our results also document step increases in groundwater temperature that coincide with threshold recharge events from the till-overburden into the deep bedrock aquifer. Similarly, temperatures in the shallow water table showed high variability with weak or no correlation to air temperature. Our investigation to helps demonstrate how the coupling of air and stream temperature can be mitigated by the hydrologic dynamics of the critical zone interface.

  3. Pesticides in Streams in Central Nebraska

    USGS Publications Warehouse

    Stamer, J.K.; Wieczorek, Michael E.

    1995-01-01

    Contamination of surface and ground water from non-point sources is a national issue. Examples of nonpoint-source contaminants from agricultural activities are pesticides, which include fungicides, herbicides, and insecticides; sediment; nutrients (nitrogen and phosphorus); and fecal bacteria. Of these contaminants, pesticides receive the most attention because of the potential toxicity to aquatic life and to humans. Most farmers use pesticides to increase crop yields and values. Herbicides prevent or inhibit the growth of weeds that compete for nutrients and moisture needed by the crops. Herbicides are applied before, during, or following planting. In addition to agricultural use, herbicides are used in urban areas, often in larger rates of application, for weed control such as among rights-of-way. Alachlor, atrazine, cyanazine, and metolachlor, which are referred to as organonitrogen herbicides, were the four most commonly applied herbicides (1991) in the Central Nebraska Basins (CNB). These herbicides are used for corn, sorghum, and soybean production. Atrazine was the most extensively applied pesticide (1991) in central Nebraska. Insecticides are used to protect the crop seeds in storage prior to planting and also to protect the plants from destruction once the seeds have germinated. Like herbicides, insecticides are also used in urban areas to protect lawns, trees, and ornamentals. Many of the 46 pesticides shown in the table have either a Maximum Contaminant Level (MCL) of Health Advisory Level (HAL) established by the U.S. Environmental Protection Agency (USEPA) for public water supplies. The purposes of this Fact Sheet are to (1) to provide water-utility managers, water-resources planners and managers, and State regulators an improved understanding of the distributions of concentrations of pesticides in streams and their relation to respective drinking-water regulations or criteria, and (2) to describe concentrations of pesticides in streams draining a

  4. Dissolved phosphorus retention and release from southeastern USA Coastal Plain in-stream wetlands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the southeastern USA Coastal Plain region, many inland surface water systems will meander through flat or depressional landscape areas prior to discharge into coastal estuaries. Slow water flow through these areas often causes flooding that promotes formation of in-stream wetlands with dense vege...

  5. Stream Restoration as a Seminar Theme: Opportunities for Synthesis and Integration

    ERIC Educational Resources Information Center

    Moran, Sharon

    2003-01-01

    By using stream restoration as a seminar theme, geography faculty can create a topical course that helps provide a shared intellectual agenda for both physical and human geography students, while highlighting the holistic strengths of our discipline. Although it is not necessary that faculty have prior knowledge about the topic, a willingness to…

  6. The Big-Fish-Little-Pond Effect and a National Policy of Within-School Ability Streaming: Alternative Frames of Reference

    ERIC Educational Resources Information Center

    Liem, Gregory Arief D.; Marsh, Herbert W.; Martin, Andrew J.; McInerney, Dennis M.; Yeung, Alexander S.

    2013-01-01

    The big-fish-little-pond effect (BFLPE) was evaluated with 4,461 seventh to ninth graders in Singapore where a national policy of ability streaming is implemented. Consistent with the BFLPE, when prior achievement was controlled, students in the high-ability stream had lower English and mathematics self-concepts (ESCs and MSCs) and those in the…

  7. A model for evaluating stream temperature response to climate change in Wisconsin

    USGS Publications Warehouse

    Stewart, Jana S.; Westenbroek, Stephen M.; Mitro, Matthew G.; Lyons, John D.; Kammel, Leah E.; Buchwald, Cheryl A.

    2015-01-01

    Integrating the SWB Model with the ANN Model provided a mechanism by which downscaled global or regional climate model results could be used to estimate the potential effects of climate change on future stream temperature on a daily time step. To address future climate scenarios, statistically downscaled air temperature and precipitation projections from 10 GCMs and 2 time periods were used with the SWB-ANNv1 Model to project future stream temperature. Projections of future stream temperatures at mid- (2046–65) and late- (2081–2100) 21st century showed the July mean water temperature increasing for all stream segments with about 80 percent of stream kilometers increasing by 1 to 2 degrees Celsius (°C) by mid-century and about 99 percent increasing by 1 to 3 °C by late-century. Projected changes in stream temperatures also affected changes in thermal classes with a loss in the total amount of cold-water, cold-transition, and warm-transition thermal habitat and a gain in warm-water and very warm thermal habitat for both mid- and late-21st century time periods. The greatest losses occurred for cold-water streams and the greatest gains for warm-water streams, with a contraction of cold-water streams in the Driftless Area of western and southern Wisconsin and an expansion of warm-water streams across northern Wisconsin. Results of this study suggest that such changes will affect the composition of fish assemblages, with a loss of suitable habitat for cold-water fishes and gain in suitable habitat for warm-water fishes. In the end, these projected changes in thermal habitat attributable to climate may result in a net loss of fisheries, because many warm-water species may be unable to colonize habitats formerly occupied by cold-water species because of other habitat limitations (e.g., stream size, gradient). Although projected stream temperatures may vary greatly, depending on the emissions scenario and models used, the results presented in this report represent one

  8. Interacting geometric priors for robust multimodel fitting.

    PubMed

    Pham, Trung Thanh; Chin, Tat-Jun; Schindler, Konrad; Suter, David

    2014-10-01

    Recent works on multimodel fitting are often formulated as an energy minimization task, where the energy function includes fitting error and regularization terms, such as low-level spatial smoothness and model complexity. In this paper, we introduce a novel energy with high-level geometric priors that consider interactions between geometric models, such that certain preferred model configurations may be induced.We argue that in many applications, such prior geometric properties are available and should be fruitfully exploited. For example, in surface fitting to point clouds, the building walls are usually either orthogonal or parallel to each other. Our proposed energy function is useful in dealing with unknown distributions of data errors and outliers, which are often the factors leading to biased estimation. Furthermore, the energy can be efficiently minimized using the expansion move method. We evaluate the performance on several vision applications using real data sets. Experimental results show that our method outperforms the state-of-the-art methods without significant increase in computation.

  9. How prior expectations shape multisensory perception.

    PubMed

    Gau, Remi; Noppeney, Uta

    2016-01-01

    The brain generates a representation of our environment by integrating signals from a common source, but segregating signals from different sources. This fMRI study investigated how the brain arbitrates between perceptual integration and segregation based on top-down congruency expectations and bottom-up stimulus-bound congruency cues. Participants were presented audiovisual movies of phonologically congruent, incongruent or McGurk syllables that can be integrated into an illusory percept (e.g. "ti" percept for visual «ki» with auditory /pi/). They reported the syllable they perceived. Critically, we manipulated participants' top-down congruency expectations by presenting McGurk stimuli embedded in blocks of congruent or incongruent syllables. Behaviorally, participants were more likely to fuse audiovisual signals into an illusory McGurk percept in congruent than incongruent contexts. At the neural level, the left inferior frontal sulcus (lIFS) showed increased activations for bottom-up incongruent relative to congruent inputs. Moreover, lIFS activations were increased for physically identical McGurk stimuli, when participants segregated the audiovisual signals and reported their auditory percept. Critically, this activation increase for perceptual segregation was amplified when participants expected audiovisually incongruent signals based on prior sensory experience. Collectively, our results demonstrate that the lIFS combines top-down prior (in)congruency expectations with bottom-up (in)congruency cues to arbitrate between multisensory integration and segregation.

  10. Dynamic visualization of data streams

    DOEpatents

    Wong, Pak Chung; Foote, Harlan P.; Adams, Daniel R.; Cowley, Wendy E.; Thomas, James J.

    2009-07-07

    One embodiment of the present invention includes a data communication subsystem to receive a data stream, and a data processing subsystem responsive to the data communication subsystem to generate a visualization output based on a group of data vectors corresponding to a first portion of the data stream. The processing subsystem is further responsive to a change in rate of receipt of the data to modify the visualization output with one or more other data vectors corresponding to a second portion of the data stream as a function of eigenspace defined with the group of data vectors. The system further includes a display device responsive to the visualization output to provide a corresponding visualization.

  11. Meteoroid streams and comet disintegration

    NASA Astrophysics Data System (ADS)

    Guliyev, A.

    2016-01-01

    The results of the statistical analysis of the dynamic parameters of 114 comets that have undergone nuclear splitting are presented in the article. The list of the objects contains: comets that have split in the period of the observation; data of twin-comets; lost comets with designation D; comets with large-scale structure in the coma. We will describe these comets as "splitted". Some aspects of the following hypothesis are studied: disintegration of comet nuclei happens as the result of their collision with meteoroid streams. For the verification of this hypothesis, the position of splitted comet orbits relatively to 125 meteor streams from Kronk's list is analyzed. It was found that the total number of comet orbit nodes located close to the meteor stream planes (for the distances up to 0.1 AU) is N = 1041. It is shown that if these comets are replaced by randomly selected different comets, N will be reduced by a factor of approximately three.

  12. Experimental and analytical investigation of acoustic streaming generated by standing ultrasonic waves in an open boundaries

    NASA Astrophysics Data System (ADS)

    Kwon, K.; Loh, B.-G.; Lee, D.-R.

    2007-12-01

    Acoustic streaming patterns, velocity fields, which is induced by a cylindrical ultrasonic exciter vibrating at 28.4kHz in an open physical boundaries, is analytically and experimentally investigated using Particle Imaging Velocimetry (PIV). Induced acoustic streaming patterns and velocity fields for the gaps of 18mm at which the irrotational tangential velocity becomes a maximum, resulting in a substantial increase in the acoustic streaming velocity and pronounced visualization of streaming patterns between the vibrator and quiescent glass plate are presented. The overall air flow patterns at the gaps of 24, 30, 36mm are similar to the gap of 18 mm but as the gap increases the frequency of occurrence and irregularity of vortices in the gap appear to increase. The symmetric definite steady circular flow with local vortices is observed. The maximum streaming velocity measured stands at 0.16 cm/s with a vibration amplitude of 50 micrometers. Theoretical analysis indicates that the pattern of air flow in the gap is determined by the top and bottom limiting velocities induced by acoustic streaming within the Stokes boundary layer and that the streaming pattern is symmetrical with respect to the center axis of the vibrator by reason of symmetry. The comparison between the experimental data and the theoretical estimation based on Nyborg and Jackson is performed.

  13. Sensitivity Analysis and Assessment of Prior Model Probabilities in MLBMA with Application to Unsaturated Fractured Tuff

    SciTech Connect

    Ye, Ming; Neuman, Shlomo P.; Meyer, Philip D.; Pohlmann, Karl

    2005-12-24

    Previous application of Maximum Likelihood Bayesian Model Averaging (MLBMA, Neuman [2002, 2003]) to alternative variogram models of log air permeability data in fractured tuff has demonstrated its effectiveness in quantifying conceptual model uncertainty and enhancing predictive capability [Ye et al., 2004]. A question remained how best to ascribe prior probabilities to competing models. In this paper we examine the extent to which lead statistics of posterior log permeability predictions are sensitive to prior probabilities of seven corresponding variogram models. We then explore the feasibility of quantifying prior model probabilities by (a) maximizing Shannon's entropy H [Shannon, 1948] subject to constraints reflecting a single analyst's (or a group of analysts?) prior perception about how plausible each alternative model (or a group of models) is relative to others, and (b) selecting a posteriori the most likely among such maxima corresponding to alternative prior perceptions of various analysts or groups of analysts. Another way to select among alternative prior model probability sets, which however is not guaranteed to yield optimum predictive performance (though it did so in our example) and would therefore not be our preferred option, is a min-max approach according to which one selects a priori the set corresponding to the smallest value of maximum entropy. Whereas maximizing H subject to the prior perception of a single analyst (or group) maximizes the potential for further information gain through conditioning, selecting the smallest among such maxima gives preference to the most informed prior perception among those of several analysts (or groups). We use the same variogram models and log permeability data as Ye et al. [2004] to demonstrate that our proposed approach yields the least amount of posterior entropy (residual uncertainty after conditioning) and enhances predictive model performance as compared to (a) the non-informative neutral case in

  14. Temperature of the Gulf Stream

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Gulf Stream is one of the strong ocean currents that carries warm water from the sunny tropics to higher latitudes. The current stretches from the Gulf of Mexico up the East Coast of the United States, departs from North America south of the Chesapeake Bay, and heads across the Atlantic to the British Isles. The water within the Gulf Stream moves at the stately pace of 4 miles per hour. Even though the current cools as the water travels thousands of miles, it remains strong enough to moderate the Northern European climate. The image above was derived from the infrared measurements of the Moderate-resolution Imaging Spectroradiometer (MODIS) on a nearly cloud-free day over the east coast of the United States. The coldest waters are shown as purple, with blue, green, yellow, and red representing progressively warmer water. Temperatures range from about 7 to 22 degrees Celsius. The core of the Gulf Stream is very apparent as the warmest water, dark red. It departs from the coast at Cape Hatteras, North Carolina. The cool, shelf water from the north entrains the warmer outflows from the Chesapeake and Delaware Bays. The north wall of the Gulf Stream reveals very complex structure associated with frontal instabilities that lead to exchanges between the Gulf Stream and inshore waters. Several clockwise-rotating warm core eddies are evident north of the core of the Gulf Stream, which enhance the exchange of heat and water between the coastal and deep ocean. Cold core eddies, which rotate counter clockwise, are seen south of the Gulf Stream. The one closest to Cape Hatteras is entraining very warm Gulf Stream waters on its northwest circumference. Near the coast, shallower waters have warmed due to solar heating, while the deeper waters offshore are markedly cooler (dark blue). MODIS made this observation on May 8, 2000, at 11:45 a.m. EDT. For more information, see the MODIS-Ocean web page. The sea surface temperature image was created at the University of Miami using

  15. ASME PTC 47 - IGCC performance testing: Air separation issues

    SciTech Connect

    Smith, A.R.

    1998-07-01

    Air separation units have been incorporated into the designs of many gasification combined cycle projects worldwide for the supply of pressurized oxygen and nitrogen. Pressurized gaseous oxygen at a purity usually above 95% by volume is supplied to the gasification unit to partially oxidized a hydrocarbon feed to yield syngas. Nitrogen streams are used for purging and inerting purposes or for the reactor. Several facilities have incorporated integration of air and/or nitrogen streams between the gas turbine and the air separation unit to improve overall facility cost, power output and efficiency. Gasification processes that are based on air as the oxidant source may also require an air separation unit to supply pressurized nitrogen for inerting and dry fuel transport. This paper reports on the progress of PTC 47's air separation subcommittee in defining test measurement boundaries and performance parameter definitions for the testing of an air separation unit as a subsystem of the gasification combined cycle facility.

  16. Salamander occupancy in headwater stream networks

    USGS Publications Warehouse

    Grant, E.H.C.; Green, L.E.; Lowe, W.H.

    2009-01-01

    1. Stream ecosystems exhibit a highly consistent dendritic geometry in which linear habitat units intersect to create a hierarchical network of connected branches. 2. Ecological and life history traits of species living in streams, such as the potential for overland movement, may interact with this architecture to shape patterns of occupancy and response to disturbance. Specifically, large-scale habitat alteration that fragments stream networks and reduces connectivity may reduce the probability a stream is occupied by sensitive species, such as stream salamanders. 3. We collected habitat occupancy data on four species of stream salamanders in first-order (i.e. headwater) streams in undeveloped and urbanised regions of the eastern U.S.A. We then used an information-theoretic approach to test alternative models of salamander occupancy based on a priori predictions of the effects of network configuration, region and salamander life history. 4. Across all four species, we found that streams connected to other first-order streams had higher occupancy than those flowing directly into larger streams and rivers. For three of the four species, occupancy was lower in the urbanised region than in the undeveloped region. 5. These results demonstrate that the spatial configuration of stream networks within protected areas affects the occurrences of stream salamander species. We strongly encourage preservation of network connections between first-order streams in conservation planning and management decisions that may affect stream species.

  17. Riparian influences on stream fish assemblage structure in urbanizing streams

    USGS Publications Warehouse

    Roy, A.H.; Freeman, B.J.; Freeman, Mary C.

    2007-01-01

    We assessed the influence of land cover at multiple spatial extents on fish assemblage integrity, and the degree to which riparian forests can mitigate the negative effects of catchment urbanization on stream fish assemblages. Riparian cover (urban, forest, and agriculture) was determined within 30 m buffers at longitudinal distances of 200 m, 1 km, and the entire network upstream of 59 non-nested fish sampling locations. Catchment and riparian land cover within the upstream network were highly correlated, so we were unable to distinguish between those variables. Most fish assemblage variables were related to % forest and % urban land cover, with the strongest relations at the largest spatial extent of land cover (catchment), followed by riparian land cover in the 1-km and 200-m reach, respectively. For fish variables related to urban land cover in the catchment, we asked whether the influence of riparian land cover on fish assemblages was dependent on the amount of urban development in the catchment. Several fish assemblage metrics (endemic richness, endemic:cosmopolitan abundance, insectivorous cyprinid richness and abundance, and fluvial specialist richness) were all best predicted by single variable models with % urban land cover. However, endemic:cosmopolitan richness, cosmopolitan abundance, and lentic tolerant abundance were related to % forest cover in the 1-km stream reach, but only in streams that had <15% catchment urban land cover. In these cases, catchment urbanization overwhelmed the potential mitigating effects of riparian forests on stream fishes. Together, these results suggest that catchment land cover is an important driver of fish assemblages in urbanizing catchments, and riparian forests are important but not sufficient for protecting stream ecosystems from the impacts of high levels of urbanization.

  18. Prior expectations facilitate metacognition for perceptual decision.

    PubMed

    Sherman, M T; Seth, A K; Barrett, A B; Kanai, R

    2015-09-01

    The influential framework of 'predictive processing' suggests that prior probabilistic expectations influence, or even constitute, perceptual contents. This notion is evidenced by the facilitation of low-level perceptual processing by expectations. However, whether expectations can facilitate high-level components of perception remains unclear. We addressed this question by considering the influence of expectations on perceptual metacognition. To isolate the effects of expectation from those of attention we used a novel factorial design: expectation was manipulated by changing the probability that a Gabor target would be presented; attention was manipulated by instructing participants to perform or ignore a concurrent visual search task. We found that, independently of attention, metacognition improved when yes/no responses were congruent with expectations of target presence/absence. Results were modeled under a novel Bayesian signal detection theoretic framework which integrates bottom-up signal propagation with top-down influences, to provide a unified description of the mechanisms underlying perceptual decision and metacognition.

  19. NMR spectral analysis using prior knowledge

    NASA Astrophysics Data System (ADS)

    Kasai, Takuma; Nagata, Kenji; Okada, Masato; Kigawa, Takanori

    2016-03-01

    Signal assignment is a fundamental step for analyses of protein structure and dynamics with nuclear magnetic resonance (NMR). Main-chain signal assignment is achieved with a sequential assignment method and/or an amino-acid selective stable isotope labeling (AASIL) method. Combinatorial selective labeling (CSL) methods, as well as our labeling strategy, stable isotope encoding (SiCode), were developed to reduce the required number of labeled samples, since one of the drawbacks of AASIL is that many samples are needed. Signal overlapping in NMR spectra interferes with amino-acid determination by CSL and SiCode. Since spectral deconvolution by peak fitting with a gradient method cannot resolve closely overlapped signals, we developed a new method to perform both peak fitting and amino acid determination simultaneously, with a replica exchange Monte Carlo method, incorporating prior knowledge of stable-isotope labeling ratios and the amino-acid sequence of the protein.

  20. The prior statistics of object colors.

    PubMed

    Koenderink, Jan J

    2010-02-01

    The prior statistics of object colors is of much interest because extensive statistical investigations of reflectance spectra reveal highly non-uniform structure in color space common to several very different databases. This common structure is due to the visual system rather than to the statistics of environmental structure. Analysis involves an investigation of the proper sample space of spectral reflectance factors and of the statistical consequences of the projection of spectral reflectances on the color solid. Even in the case of reflectance statistics that are translationally invariant with respect to the wavelength dimension, the statistics of object colors is highly non-uniform. The qualitative nature of this non-uniformity is due to trichromacy.

  1. Improving semantic scene understanding using prior information

    NASA Astrophysics Data System (ADS)

    Laddha, Ankit; Hebert, Martial

    2016-05-01

    Perception for ground robot mobility requires automatic generation of descriptions of the robot's surroundings from sensor input (cameras, LADARs, etc.). Effective techniques for scene understanding have been developed, but they are generally purely bottom-up in that they rely entirely on classifying features from the input data based on learned models. In fact, perception systems for ground robots have a lot of information at their disposal from knowledge about the domain and the task. For example, a robot in urban environments might have access to approximate maps that can guide the scene interpretation process. In this paper, we explore practical ways to combine such prior information with state of the art scene understanding approaches.

  2. Diffusion-based spatial priors for imaging

    PubMed Central

    Harrison, L.M.; Penny, W.; Ashburner, J.; Trujillo-Barreto, N.; Friston, K.J.

    2007-01-01

    We describe a Bayesian scheme to analyze images, which uses spatial priors encoded by a diffusion kernel, based on a weighted graph Laplacian. This provides a general framework to formulate a spatial model, whose parameters can be optimized. The application we have in mind is a spatiotemporal model for imaging data. We illustrate the method on a random effects analysis of fMRI contrast images from multiple subjects; this simplifies exposition of the model and enables a clear description of its salient features. Typically, imaging data are smoothed using a fixed Gaussian kernel as a pre-processing step before applying a mass-univariate statistical model (e.g., a general linear model) to provide images of parameter estimates. An alternative is to include smoothness in a multivariate statistical model (Penny, W.D., Trujillo-Barreto, N.J., Friston, K.J., 2005. Bayesian fMRI time series analysis with spatial priors. Neuroimage 24, 350–362). The advantage of the latter is that each parameter field is smoothed automatically, according to a measure of uncertainty, given the data. In this work, we investigate the use of diffusion kernels to encode spatial correlations among parameter estimates. Nonlinear diffusion has a long history in image processing; in particular, flows that depend on local image geometry (Romeny, B.M.T., 1994. Geometry-driven Diffusion in Computer Vision. Kluwer Academic Publishers) can be used as adaptive filters. This can furnish a non-stationary smoothing process that preserves features, which would otherwise be lost with a fixed Gaussian kernel. We describe a Bayesian framework that incorporates non-stationary, adaptive smoothing into a generative model to extract spatial features in parameter estimates. Critically, this means adaptive smoothing becomes an integral part of estimation and inference. We illustrate the method using synthetic and real fMRI data. PMID:17869542

  3. Long-Term Data Reveal Patterns and Controls on Stream Water Chemistry in a Forested Stream: Walker Branch, Tennessee

    SciTech Connect

    Lutz, Brian D; Mulholland, Patrick J; Bernhardt, Emily

    2012-01-01

    We present 20 years of weekly stream water chemistry, hydrology, and climate data for the Walker Branch watershed in eastern Tennessee, USA. Since 1989, the watershed has experienced a similar to 1.08 degrees C increase in mean annual temperature, a similar to 20% decline in precipitation, and a similar to 30% increase in forest evapotranspiration rates. As a result, stream runoff has declined by similar to 34%. We evaluate long-term trends in stream water concentrations and fluxes for nine solutes and use wet deposition data to calculate approximate watershed input-output budgets. Dissolved constituents were classified as geochemical solutes (Ca2+, Mg2+, and SO42-) or nutrients (NH4+, NO3-, soluble reactive phosphorus [SRP], total soluble nitrogen [TSN], total soluble phosphorus [TSP], and dissolved organic carbon [DOC]). Geochemical solutes are predominantly controlled by discharge, and the long-term changes in catchment hydrology have led to significant trends in the concentrations and fluxes of these solutes. Further, the trends in geochemical solute concentrations indicate shifting soil flowpath contributions to streamflow generation through time, with deep groundwater having a greater proportional contribution in recent years. Despite dramatic changes in watershed runoff, there were no trends in inorganic nutrient concentrations (NH4+, NO3-, and SRP). While most nutrients entering the watershed are retained, stream fluxes of nutrient solutes have declined significantly as a result of decreasing runoff. Nutrient concentrations in the stream exhibit large seasonality controlled by in-stream biological uptake. Stream benthic communities are sensitive to hydrologic disturbance, and changes in the frequency or intensity of storm events through time can affect nutrient fluxes. Stream NO3- concentrations are also sensitive to drought, with concentrations decreasing (increasing) if conditions during the three years prior to the time of sampling were drier (wetter

  4. Sampling Interplanetary Dust Particles from Antarctic Air

    NASA Astrophysics Data System (ADS)

    Taylor, S.; Lever, J. H.; Alexander, C. M. O'D.; Brownlee, D. E.; Messenger, S.; Littler, L. R.; Stroud, R. M.; Wozniakiewicz, P.; Clement, S.

    2016-08-01

    We are undertaking a NASA and NSF supported project to filter large volumes of clean Antarctic air to collect a broad range of cosmic dust, including CP-IDPs, rare ultra-carbonaceous particles and particles derived from specific meteor streams.

  5. Estimation of stream temperature in support of fish production modeling under future climates in the Klamath River Basin

    USGS Publications Warehouse

    Flint, Lorraine E.; Flint, Alan L.

    2012-01-01

    Stream temperature estimates under future climatic conditions were needed in support of fish production modeling for evaluation of effects of dam removal in the Klamath River Basin. To allow for the persistence of the Klamath River salmon fishery, an upcoming Secretarial Determination in 2012 will review potential changes in water quality and stream temperature to assess alternative scenarios, including dam removal. Daily stream temperature models were developed by using a regression model approach with simulated net solar radiation, vapor density deficit calculated on the basis of air temperature, and mean daily air temperature. Models were calibrated for 6 streams in the Lower, and 18 streams in the Upper, Klamath Basin by using measured stream temperatures for 1999-2008. The standard error of the y-estimate for the estimation of stream temperature for the 24 streams ranged from 0.36 to 1.64°C, with an average error of 1.12°C for all streams. The regression models were then used with projected air temperatures to estimate future stream temperatures for 2010-99. Although the mean change from the baseline historical period of 1950-99 to the projected future period of 2070-99 is only 1.2°C, it ranges from 3.4°C for the Shasta River to no change for Fall Creek and Trout Creek. Variability is also evident in the future with a mean change in temperature for all streams from the baseline period to the projected period of 2070-99 of only 1°C, while the range in stream temperature change is from 0 to 2.1°C. The baseline period, 1950-99, to which the air temperature projections were corrected, established the starting point for the projected changes in air temperature. The average measured daily air temperature for the calibration period 1999-2008, however, was found to be as much as 2.3°C higher than baseline for some rivers, indicating that warming conditions have already occurred in many areas of the Klamath River Basin, and that the stream temperature

  6. Oxygen Sag and Stream Purification.

    ERIC Educational Resources Information Center

    Neal, Larry; Herwig, Roy

    1978-01-01

    Presents a literature review of water quality related to oxygen sag and stream purification, covering publications of 1976-77. This review includes: (1) self-purification models; (2) oxygen demand; and (3) reaeration and oxygen transfer. A list of 60 references is also presented. (HM)

  7. Frequency response of ice streams.

    PubMed

    Williams, C Rosie; Hindmarsh, Richard C A; Arthern, Robert J

    2012-11-01

    Changes at the grounding line of ice streams have consequences for inland ice dynamics and hence sea level. Despite substantial evidence documenting upstream propagation of frontal change, the mechanisms by which these changes are transmitted inland are not well understood. In this vein, the frequency response of an idealized ice stream to periodic forcing in the downstream strain rate is examined for basally and laterally resisted ice streams using a one-dimensional, linearized membrane stress approximation. This reveals two distinct behavioural branches, which we find to correspond to different mechanisms of upstream velocity and thickness propagation, depending on the forcing frequency. At low frequencies (centennial to millennial periods), slope and thickness covary hundreds of kilometres inland, and the shallow-ice approximation is sufficient to explain upstream propagation, which occurs through changes in grounding-line flow and geometry. At high frequencies (decadal to sub-decadal periods), penetration distances are tens of kilometres; while velocity adjusts rapidly to such forcing, thickness varies little and upstream propagation occurs through the direct transmission of membrane stresses. Propagation properties vary significantly between 29 Antarctic ice streams considered. A square-wave function in frontal stress is explored by summing frequency solutions, simulating some aspects of the dynamical response to sudden ice-shelf change.

  8. Stream Profiles, An Environmental Investigation.

    ERIC Educational Resources Information Center

    National Wildlife Federation, Washington, DC.

    This environmental unit is one of a series designed for integration within an existing curriculum. The unit is self-contained and requires minimal teacher preparation. The philosophy of the units is based on an experience-oriented process that encourages self-paced independent student work. In this unit, students construct a stream profile based…

  9. POPULATION DECLINE IN STREAM FISH

    EPA Science Inventory

    Over half of the streams in the Mid-Atlantic Highlands have fish communities that are in fair or poor condition, and the EPA concluded that physical habitat alteration represents the greatest potential stressor across this region. A quantitative method for relating habitat quali...

  10. Characterization of gluten processing streams.

    PubMed

    Rausch, K D; Thompson, C I; Belyea, R L; Clevenger, T E; Tumbleson, M E

    2003-09-01

    Corn gluten meal (CGM) is a major coproduct of corn wet milling; it has value because of high protein. However, variation in composition and high P content reduce market value. Data that characterize gluten streams would be helpful in identifying key processing steps that could be modified to improve the quality of CGM and increase processing efficiency. Few data are published in the literature on the detailed composition of gluten processing streams. The objective was to characterize the gluten process streams in a corn wet milling plant. Samples were obtained from one plant over a six month period and analyzed for dry matter (DM), total N (protein), ash and elements. DM and macroelement content of the streams were increased significantly during processing. Ash, priority pollutant elements and microelement concentrations were low and of little concern. About 38% of the N (protein) in light gluten was not recovered in the CGM; most of this was lost at the gluten thickener step into the gluten thickener overflow. Much of the P also was removed at this step. Modification of the gluten thickener overflow to increase N and reduce P could make CGM a more valuable coproduct and improve processing efficiency.

  11. Frequency response of ice streams.

    PubMed

    Williams, C Rosie; Hindmarsh, Richard C A; Arthern, Robert J

    2012-11-01

    Changes at the grounding line of ice streams have consequences for inland ice dynamics and hence sea level. Despite substantial evidence documenting upstream propagation of frontal change, the mechanisms by which these changes are transmitted inland are not well understood. In this vein, the frequency response of an idealized ice stream to periodic forcing in the downstream strain rate is examined for basally and laterally resisted ice streams using a one-dimensional, linearized membrane stress approximation. This reveals two distinct behavioural branches, which we find to correspond to different mechanisms of upstream velocity and thickness propagation, depending on the forcing frequency. At low frequencies (centennial to millennial periods), slope and thickness covary hundreds of kilometres inland, and the shallow-ice approximation is sufficient to explain upstream propagation, which occurs through changes in grounding-line flow and geometry. At high frequencies (decadal to sub-decadal periods), penetration distances are tens of kilometres; while velocity adjusts rapidly to such forcing, thickness varies little and upstream propagation occurs through the direct transmission of membrane stresses. Propagation properties vary significantly between 29 Antarctic ice streams considered. A square-wave function in frontal stress is explored by summing frequency solutions, simulating some aspects of the dynamical response to sudden ice-shelf change. PMID:23197934

  12. ALIENS IN WESTERN STREAM ECOSYSTEMS

    EPA Science Inventory

    The USEPA's Environmental Monitoring and Assessment Program conducted a five year probability sample of permanent mapped streams in 12 western US states. The study design enables us to determine the extent of selected riparian invasive plants, alien aquatic vertebrates, and some ...

  13. Video Streaming in Online Learning

    ERIC Educational Resources Information Center

    Hartsell, Taralynn; Yuen, Steve Chi-Yin

    2006-01-01

    The use of video in teaching and learning is a common practice in education today. As learning online becomes more of a common practice in education, streaming video and audio will play a bigger role in delivering course materials to online learners. This form of technology brings courses alive by allowing online learners to use their visual and…

  14. Streams in the urban heat island: spatial and temporal variability in temperature

    USGS Publications Warehouse

    Somers, Kayleigh A.; Bernhardt, Emily S.; Grace, James B.; Hassett, Brooke A.; Sudduth, Elizabeth B.; Wang, Siyi; Urban, Dean L.

    2013-01-01

    Streams draining urban heat islands tend to be hotter than rural and forested streams at baseflow because of warmer urban air and ground temperatures, paved surfaces, and decreased riparian canopy. Urban infrastructure efficiently routes runoff over hot impervious surfaces and through storm drains directly into streams and can lead to rapid, dramatic increases in temperature. Thermal regimes affect habitat quality and biogeochemical processes, and changes can be lethal if temperatures exceed upper tolerance limits of aquatic fauna. In summer 2009, we collected continuous (10-min interval) temperature data in 60 streams spanning a range of development intensity in the Piedmont of North Carolina, USA. The 5 most urbanized streams averaged 21.1°C at baseflow, compared to 19.5°C in the 5 most forested streams. Temperatures in urban streams rose as much as 4°C during a small regional storm, whereas the same storm led to extremely small to no changes in temperature in forested streams. Over a kilometer of stream length, baseflow temperature varied by as much as 10°C in an urban stream and as little as 2°C in a forested stream. We used structural equation modeling to explore how reach- and catchment-scale attributes interact to explain maximum temperatures and magnitudes of storm-flow temperature surges. The best predictive model of baseflow temperatures (R2  =  0.461) included moderately strong pathways directly (extent of development and road density) and indirectly, as mediated by reach-scale factors (canopy closure and stream width), from catchment-scale factors. The strongest influence on storm-flow temperature surges appeared to be % development in the catchment. Reach-scale factors, such as the extent of riparian forest and stream width, had little mitigating influence (R2  =  0.448). Stream temperature is an essential, but overlooked, aspect of the urban stream syndrome and is affected by reach-scale habitat variables, catchment-scale urbanization

  15. Rebound of continuous droplet streams from an immiscible liquid pool

    NASA Astrophysics Data System (ADS)

    Doak, William J.; Laiacona, Danielle M.; German, Guy K.; Chiarot, Paul R.

    2016-05-01

    We report on the rebound of high velocity continuous water droplet streams from the surface of an immiscible oil pool. The droplets have diameters and velocities of less than 90 μm and 15 m/s, respectively, and were created at frequencies up to 60 kHz. The impact and rebound of continuous droplet streams at this scale and velocity have been largely unexplored. This regime bridges the gap between single drop and jet impacts. The impinging droplets create a divot at the surface of the oil pool that had a common characteristic shape across a wide-range of droplet and oil properties. After impact, the reflected droplets maintain the same uniformity and periodicity of the incoming droplets but have significantly lower velocity and kinetic energy. This was solely attributed to the generation of a flow induced in the viscous oil pool by the impacting droplets. Unlike normally directed impact of millimeter-scale droplets with a solid surface, our results show that an air film does not appear to be maintained beneath the droplets during impact. This suggests direct contact between the droplets and the surface of the oil pool. A ballistic failure limit, correlated with the Weber number, was identified where the rebound was suppressed and the droplets were driven through the oil surface. A secondary failure mode was identified for aperiodic incoming streams. Startup effects and early time dynamics of the rebounding droplet stream were also investigated.

  16. In-stream hydrokinetic power: Review and appraisal

    SciTech Connect

    Van Zwieten, J.; McAnally, William; Ahmad, Jameel; Davis, Trey; Martin, James; Bevelhimer, Mark S.; Cribbs, Allison; Lippert, Renee; Hudon, Thomas; Trudeau, Matthew

    2015-09-01

    The objective of this paper is to provide a review of in-stream hydrokinetic power, which is defined as electric power generated by devices capturing the energy of naturally flowing water-stream, tidal, or open ocean flows-without impounding the water. North America has significant in-stream energy resources, and hydrokinetic electric power technologies to harness those resources have the potential to make a significant contribution to U.S. electricity needs by adding as much as 120 TWh/year from rivers alone to the present hydroelectric power generation capacity. Additionally, tidal and ocean current resources in the U.S. respectively contain 438 TWh/year and 163 TWh/year of extractable power. Among their attractive features, in-stream hydrokinetic operations do not contribute to greenhouse gas emissions or other air pollution and have less visual impact than wind turbines. Since these systems do no utilize dams the way traditional hydropower systems typically do, their impact on the environment will differ, and a small but growing number of studies support conclusions regarding those impacts. Furthermore, potential environmental impacts include altered water quality, altered sediment deposition, altered habitats, direct impact on biota, and navigability of waterways.

  17. In-stream hydrokinetic power: Review and appraisal

    DOE PAGES

    Van Zwieten, J.; McAnally, William; Ahmad, Jameel; Davis, Trey; Martin, James; Bevelhimer, Mark S.; Cribbs, Allison; Lippert, Renee; Hudon, Thomas; Trudeau, Matthew

    2015-09-01

    The objective of this paper is to provide a review of in-stream hydrokinetic power, which is defined as electric power generated by devices capturing the energy of naturally flowing water-stream, tidal, or open ocean flows-without impounding the water. North America has significant in-stream energy resources, and hydrokinetic electric power technologies to harness those resources have the potential to make a significant contribution to U.S. electricity needs by adding as much as 120 TWh/year from rivers alone to the present hydroelectric power generation capacity. Additionally, tidal and ocean current resources in the U.S. respectively contain 438 TWh/year and 163 TWh/year ofmore » extractable power. Among their attractive features, in-stream hydrokinetic operations do not contribute to greenhouse gas emissions or other air pollution and have less visual impact than wind turbines. Since these systems do no utilize dams the way traditional hydropower systems typically do, their impact on the environment will differ, and a small but growing number of studies support conclusions regarding those impacts. Furthermore, potential environmental impacts include altered water quality, altered sediment deposition, altered habitats, direct impact on biota, and navigability of waterways.« less

  18. Evaluation of stream chemistry trends in US Geological Survey reference watersheds, 1970-2010

    USGS Publications Warehouse

    Mast, M. Alisa

    2013-01-01

    The Hydrologic Benchmark Network (HBN) is a long-term monitoring program established by the US Geological Survey in the 1960s to track changes in the streamflow and stream chemistry in undeveloped watersheds across the USA. Trends in stream chemistry were tested at 15 HBN stations over two periods (1970–2010 and 1990–2010) using the parametric Load Estimator (LOADEST) model and the nonparametric seasonal Kendall test. Trends in annual streamflow and precipitation chemistry also were tested to help identify likely drivers of changes in stream chemistry. At stations in the northeastern USA, there were significant declines in stream sulfate, which were consistent with declines in sulfate deposition resulting from the reductions in SO2 emissions mandated under the Clean Air Act Amendments. Sulfate declines in stream water were smaller than declines in deposition suggesting sulfate may be accumulating in watershed soils and thereby delaying the stream response to improvements in deposition. Trends in stream chemistry at stations in other part of the country generally were attributed to climate variability or land disturbance. Despite declines in sulfate deposition, increasing stream sulfate was observed at several stations and appeared to be linked to periods of drought or declining streamflow. Falling water tables might have enhanced oxidation of organic matter in wetlands or pyrite in mineralized bedrock thereby increasing sulfate export in surface water. Increasing sulfate and nitrate at a station in the western USA were attributed to release of soluble salts and nutrients from soils following a large wildfire in the watershed.

  19. Evaluation of stream chemistry trends in US Geological Survey reference watersheds, 1970-2010.

    PubMed

    Mast, M Alisa

    2013-11-01

    The Hydrologic Benchmark Network (HBN) is a long-term monitoring program established by the US Geological Survey in the 1960s to track changes in the streamflow and stream chemistry in undeveloped watersheds across the USA. Trends in stream chemistry were tested at 15 HBN stations over two periods (1970-2010 and 1990-2010) using the parametric Load Estimator (LOADEST) model and the nonparametric seasonal Kendall test. Trends in annual streamflow and precipitation chemistry also were tested to help identify likely drivers of changes in stream chemistry. At stations in the northeastern USA, there were significant declines in stream sulfate, which were consistent with declines in sulfate deposition resulting from the reductions in SO₂ emissions mandated under the Clean Air Act Amendments. Sulfate declines in stream water were smaller than declines in deposition suggesting sulfate may be accumulating in watershed soils and thereby delaying the stream response to improvements in deposition. Trends in stream chemistry at stations in other part of the country generally were attributed to climate variability or land disturbance. Despite declines in sulfate deposition, increasing stream sulfate was observed at several stations and appeared to be linked to periods of drought or declining streamflow. Falling water tables might have enhanced oxidation of organic matter in wetlands or pyrite in mineralized bedrock thereby increasing sulfate export in surface water. Increasing sulfate and nitrate at a station in the western USA were attributed to release of soluble salts and nutrients from soils following a large wildfire in the watershed. PMID:23715732

  20. Evaluation of stream chemistry trends in US Geological Survey reference watersheds, 1970-2010.

    PubMed

    Mast, M Alisa

    2013-11-01

    The Hydrologic Benchmark Network (HBN) is a long-term monitoring program established by the US Geological Survey in the 1960s to track changes in the streamflow and stream chemistry in undeveloped watersheds across the USA. Trends in stream chemistry were tested at 15 HBN stations over two periods (1970-2010 and 1990-2010) using the parametric Load Estimator (LOADEST) model and the nonparametric seasonal Kendall test. Trends in annual streamflow and precipitation chemistry also were tested to help identify likely drivers of changes in stream chemistry. At stations in the northeastern USA, there were significant declines in stream sulfate, which were consistent with declines in sulfate deposition resulting from the reductions in SO₂ emissions mandated under the Clean Air Act Amendments. Sulfate declines in stream water were smaller than declines in deposition suggesting sulfate may be accumulating in watershed soils and thereby delaying the stream response to improvements in deposition. Trends in stream chemistry at stations in other part of the country generally were attributed to climate variability or land disturbance. Despite declines in sulfate deposition, increasing stream sulfate was observed at several stations and appeared to be linked to periods of drought or declining streamflow. Falling water tables might have enhanced oxidation of organic matter in wetlands or pyrite in mineralized bedrock thereby increasing sulfate export in surface water. Increasing sulfate and nitrate at a station in the western USA were attributed to release of soluble salts and nutrients from soils following a large wildfire in the watershed.

  1. A basin-scale approach to estimating stream temperatures of tributaries to the lower Klamath River, California

    USGS Publications Warehouse

    Flint, L.E.; Flint, A.L.

    2008-01-01

    Stream temperature is an important component of salmonid habitat and is often above levels suitable for fish survival in the Lower Klamath River in northern California. The objective of this study was to provide boundary conditions for models that are assessing stream temperature on the main stem for the purpose of developing strategies to manage stream conditions using Total Maximum Daily Loads. For model input, hourly stream temperatures for 36 tributaries were estimated for 1 Jan. 2001 through 31 Oct. 2004. A basin-scale approach incorporating spatially distributed energy balance data was used to estimate the stream temperatures with measured air temperature and relative humidity data and simulated solar radiation, including topographic shading and corrections for cloudiness. Regression models were developed on the basis of available stream temperature data to predict temperatures for unmeasured periods of time and for unmeasured streams. The most significant factor in matching measured minimum and maximum stream temperatures was the seasonality of the estimate. Adding minimum and maximum air temperature to the regression model improved the estimate, and air temperature data over the region are available and easily distributed spatially. The addition of simulated solar radiation and vapor saturation deficit to the regression model significantly improved predictions of maximum stream temperature but was not required to predict minimum stream temperature. The average SE in estimated maximum daily stream temperature for the individual basins was 0.9 ?? 0.6??C at the 95% confidence interval. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  2. Sediment transported by Georgia streams

    USGS Publications Warehouse

    Kennedy, Vance C.

    1964-01-01

    A reconnaissance investigation of the sediment transported by selected Georgia streams during the period December 1957 to June 1959 was made to provide a general understanding of the physical quality of stream water in Georgia and to supply facts needed in planning more detailed work. The investigation was made by studying the variation of sediment concentration and sediment load with stream discharge at 33 sites and by relating the available data to topographic, geologic, climatic, and soil conditions in the State. In the Blue Ridge Mountains area of northern Georgia the great relief, moderately heavy precipitation, fast runoff, and loamy soils cause sediment concentrations and sediment loads which are above average for the State. During periods of moderate to low streamflow, the concentration of suspended sediment ranges from 1 to 25 ppm (parts per million). After heavy rainfall, sediment concentration increases rapidly as water discharge rises, and occasionally exceeds 1,000 ppm before decreasing again. The concentration may reach a maximum and decrease before the discharge peak is reached. A major part of the annual sediment load can be carried during a short period of time because of the great increase in both water discharge and sediment concentration during floods. The lower Coastal Plain differs from the mountainous areas in several respects. The topography is gently rolling to almost level, precipitation and runoff are less than average for the State, and topsoils generally consist of hard and loamy sand. Concentration of suspended sediment in streamflow commonly ranges from 1 to 20 ppm during periods of low to moderate discharge and increases to 15 to 60 ppm at high discharge. Because of the small increase in concentration with increasing stream discharge, the sediment load varies approximately in proportion to the discharge. The sediment characteristics of streams in the Piedmont, the Valley and Ridge area. and the upper Coastal Plain are intermediate

  3. Ambient air quality monitoring plan, Cumberland Steam Plant

    SciTech Connect

    Owen, A.E. Jr.; Carter, R.V.

    1981-09-01

    The Tennessee Valley Authority (TVA) has conducted ambient air quality monitoring at Cumberland Steam Plant since 1971. The monitoring network was operated to collect background air quality information prior to plant startup (1972) and to document ambient air quality after the plant reached full operating levels in 1973. This monitoring plan presents a new network design for Cumberland Steam Plant.

  4. Stream Physical Characteristics Impact Habitat Quality for Pacific Salmon in Two Temperate Coastal Watersheds

    PubMed Central

    Fellman, Jason B.; Hood, Eran; Dryer, William; Pyare, Sanjay

    2015-01-01

    Climate warming is likely to cause both indirect and direct impacts on the biophysical properties of stream ecosystems especially in regions that support societally important fish species such as Pacific salmon. We studied the seasonal variability and interaction between stream temperature and DO in a low-gradient, forested stream and a glacial-fed stream in coastal southeast Alaska to assess how these key physical parameters impact freshwater habitat quality for salmon. We also use multiple regression analysis to evaluate how discharge and air temperature influence the seasonal patterns in stream temperature and DO. Mean daily stream temperature ranged from 1.1 to 16.4°C in non-glacial Peterson Creek but only 1.0 to 8.8°C in glacial-fed Cowee Creek, reflecting the strong moderating influence glacier meltwater had on stream temperature. Peterson Creek had mean daily DO concentrations ranging from 3.8 to 14.1 mg L−1 suggesting future climate changes could result in an even greater depletion in DO. Mean daily stream temperature strongly controlled mean daily DO in both Peterson (R2=0.82, P<0.01) and Cowee Creek (R2=0.93, P<0.01). However, DO in Peterson Creek was mildly related to stream temperature (R2=0.15, P<0.01) and strongly influenced by discharge (R2=0.46, P<0.01) on days when stream temperature exceeded 10°C. Moreover, Peterson Creek had DO values that were particularly low (<5.0 mg L−1) on days when discharge was low but also when spawning salmon were abundant. Our results demonstrate the complexity of stream temperature and DO regimes in coastal temperate watersheds and highlight the need for watershed managers to move towards multi-factor risk assessment of potential habitat quality for salmon rather than single factor assessments alone. PMID:26222506

  5. Iodine Pathways and Off-Gas Stream Characteristics for Aqueous Reprocessing Plants – A Literature Survey and Assessment

    SciTech Connect

    R. T. Jubin; D. M. Strachan; N. R. Soelberg

    2013-09-01

    Used nuclear fuel is currently being reprocessed in only a few countries, notably France, England, Japan, and Russia. The need to control emissions of the gaseous radionuclides to the air during nuclear fuel reprocessing has already been reported for the entire plant. But since the gaseous radionuclides can partition to various different reprocessing off-gas streams, for example, from the head end, dissolver, vessel, cell, and melter, an understanding of each of these streams is critical. These off-gas streams have different flow rates and compositions and could have different gaseous radionuclide control requirements, depending on how the gaseous radionuclides partition. This report reviews the available literature to summarize specific engineering data on the flow rates, forms of the volatile radionuclides in off-gas streams, distributions of these radionuclides in these streams, and temperatures of these streams. This document contains an extensive bibliography of the information contained in the open literature.

  6. Air Pollution.

    ERIC Educational Resources Information Center

    Fox, Donald L.

    1989-01-01

    Materials related to air pollution are reviewed for the period January 1987, to October 1988. The topics are pollution monitoring, air pollution, and environmental chemistry. The organization consists of two major analytical divisions: (1) gaseous methods; and (2) aerosol and particulate methods. (MVL)

  7. Air Pollution.

    EPA Science Inventory

    Air quality is affected by many types of pollutants that are emitted from various sources, including stationary and mobile. These sources release both criteria and hazardous air pollutants, which cause health effects, ecological harm, and material damage. They are generally categ...

  8. Aeroacoustics of Three-Stream Jets

    NASA Technical Reports Server (NTRS)

    Henderson, Brenda S.

    2012-01-01

    Results from acoustic measurements of noise radiated from a heated, three-stream, co-annular exhaust system operated at subsonic conditions are presented. The experiments were conducted for a range of core, bypass, and tertiary stream temperatures and pressures. The nozzle system had a fan-to-core area ratio of 2.92 and a tertiary-to-core area ratio of 0.96. The impact of introducing a third stream on the radiated noise for third-stream velocities below that of the bypass stream was to reduce high frequency noise levels at broadside and peak jet-noise angles. Mid-frequency noise radiation at aft observation angles was impacted by the conditions of the third stream. The core velocity had the greatest impact on peak noise levels and the bypass-to-core mass flow ratio had a slight impact on levels in the peak jet-noise direction. The third-stream jet conditions had no impact on peak noise levels. Introduction of a third jet stream in the presence of a simulated forward-flight stream limits the impact of the third stream on radiated noise. For equivalent ideal thrust conditions, two-stream and three-stream jets can produce similar acoustic spectra although high-frequency noise levels tend to be lower for the three-stream jet.

  9. Effects of Stream Channel Characteristics on Nitrate Delivery to Streams and In-Stream Denitrification Rates, Raccoon River, Iowa

    NASA Astrophysics Data System (ADS)

    Prestegaard, K. L.; O'Connell, M.

    2004-05-01

    Streams in agricultural areas often exhibit significant channel and sediment modifications; they are often incised and transport more fine sediment than non-agricultural streams. These channel characteristics can influence stream water quality by modifying surface-groundwater interactions. In the Raccoon River basin, channel incision increases the delivery of nitrate from the groundwater to the streams. The sandy in-stream sediments, however, serve as very effective sites for in-stream denitrification. Nitrate delivery and in-stream denitrification was examined in 3 subwatersheds of the Raccoon River. Stream morphology, water quality, and sediment characteristics were measured at 35 sites with varying land uses. Headwater stream nitrate concentration increased with percent row crops and the amount of channel incision. Downstream sites showed a wide variation in nitrate concentration with land use. Stream nitrate concentrations were measured at 6 sites in each of 3 streams with high percentages of row crop land uses during high summer baseflow following the 1993 floods and during average summer baseflow in 1995. Nitrate concentrations were systematically higher for the high baseflow conditions of 1993 than the average year (1995). This change in nitrate concentration is interpreted as the increased effectiveness of nitrate delivery to the stream during periods of high water tables. The effect was most pronounced in incised reaches. All 3 streams show downstream decreases in nitrate concentration. Water samples for all the sites in the watersheds were analyzed for nitrogen isotopic composition. The nitrogen isotopic composition shifts with towards higher d 15N values with decreasing nitrate concentration. This is consistent with denitrification reactions that selectively remove the 14N leaving a higher proportion of 15N in the nitrate. This suggests that most of the downstream decrease in nitrate concentrations is a result of in-stream denitrification. The high rates

  10. Air stripping of aqueous solutions. Engineering bulletin

    SciTech Connect

    Not Available

    1991-10-01

    Air stripping is a means to transfer contaminants from aqueous solutions to air. Contaminants are not destroyed by air stripping but are physically separated from the aqueous solutions. Contaminant vapors are transferred into the air stream and, if necessary, can be treated by incineration, adsorption, or oxidation. Most frequently, contaminants are collected in carbon adsorption systems and then treated or destroyed in this concentrated form. The concentrated contaminants may be recovered, incinerated for waste heat recovery, or destroyed by other treatment technologies. Generally, air stripping is used as one in a series of unit operations and can reduce the overall cost for managing a particular site. Air stripping is applicable to volatile and semivolatile organic compounds. It is not applicable for treating metals and inorganic compounds. The bulletin provides information on the technology applicability, the technology limitations, a description of the technology, the types of residuals produced, site requirements, the latest performance data, the status of the technology, and sources of further information.

  11. Convective Heat Transfer in Acoustic Streaming Flows

    NASA Astrophysics Data System (ADS)

    Gopinath, Ashok

    1992-01-01

    Convective heat transfer due to acoustic streaming has been studied in the absence of an imposed mean flow. The work is motivated by the need to design and control the thermal features of a suitable experimental rig for the containerless processing of materials by heat treatment of acoustically levitated alloy samples at near zero-gravity. First the problem of heat transfer from an isolated sphere (in a standing sound field) is explored in detail. The streaming Reynolds number, Rs, which characterizes the resulting steady flows, is determined from the acoustic signal. A scale analysis is used to ascertain the importance of buoyancy and viscous dissipation. The steady velocity and temperature fields are determined using asymptotic techniques and numerical methods for the limiting cases of Rs<<1 and Rsgg1. Working correlations for the average Nusselt number are obtained for a wide range of Prandtl numbers. A simple experiment is conducted to verify the predictions for the more relevant case of Rsgg1. The acoustic levitation chamber itself is modelled as a Kundt tube (supporting a plane axial standing sound wave) with insulated side-wall and isothermal end-walls. Analytical solution techniques are used to determine the steady fields close to the tube walls. For the steady recirculatory transport in the core, the numerical solver PHOENICS is adopted for the solution of the complete elliptic form of the governing equations. A study of the effects of a range of acoustic and geometric parameters on the flow and heat transfer is performed and Nusselt number correlations are obtained for air. PHOENICS is also used to study the effects of variable fluid properties and axial side-wall conduction (coupled with radiation). The role of normal/reduced gravity is assessed and suggestions made for terrestrial testing of the levitation apparatus. Finally, with the sample located at a node in the levitation chamber, the effect of the interaction of the streaming flows (on the sphere

  12. Multichannel Speech Enhancement Based on Generalized Gamma Prior Distribution with Its Online Adaptive Estimation

    NASA Astrophysics Data System (ADS)

    Dat, Tran Huy; Takeda, Kazuya; Itakura, Fumitada

    We present a multichannel speech enhancement method based on MAP speech spectral magnitude estimation using a generalized gamma model of speech prior distribution, where the model parameters are adapted from actual noisy speech in a frame-by-frame manner. The utilization of a more general prior distribution with its online adaptive estimation is shown to be effective for speech spectral estimation in noisy environments. Furthermore, the multi-channel information in terms of cross-channel statistics are shown to be useful to better adapt the prior distribution parameters to the actual observation, resulting in better performance of speech enhancement algorithm. We tested the proposed algorithm in an in-car speech database and obtained significant improvements of the speech recognition performance, particularly under non-stationary noise conditions such as music, air-conditioner and open window.

  13. Did the pre-1980 use of in-stream structures improve streams? A reanalysis of historical data.

    PubMed

    Thompson, Douglas M

    2006-04-01

    In the 1930s, after only three years of scientific investigation at the University of Michigan Institute for Fisheries Research, cheap labor and government-sponsored conservation projects spearheaded by the Civilian Conservation Corps allowed the widespread adoption of in-stream structures throughout the United States. From the 1940s through the 1970s, designs of in-stream structures remained essentially unchanged, and their use continued. Despite a large investment in the construction of in-stream structures over these four decades, very few studies were undertaken to evaluate the impacts of the structures on the channel and its aquatic populations. The studies that were undertaken to evaluate the impact of the structures were often flawed. The use of habitat structures became an "accepted practice," however, and early evaluation studies were used as proof that the structures were beneficial to aquatic organisms. A review of the literature reveals that, despite published claims to the contrary, little evidence of the successful use of in-stream structures to improve fish populations exists prior to 1980. A total of 79 publications were checked, and 215 statistical analyses were performed. Only seven analyses provide evidence for a benefit of structures on fish populations, and five of these analyses are suspect because data were misclassified by the original authors. Many of the changes in population measures reported in early publications appear to result from changes in fishing pressure that often accompanied channel modifications. Modern evaluations of channel-restoration projects must consider the influence of fishing pressure to ensure that efforts to improve fish habitat achieve the benefits intended. My statistical results show that the traditional use of in-stream structures for channel restoration design does not ensure demonstrable benefits for fish communities, and their ability to increase fish populations should not be presumed.

  14. Microbial Transport, Retention, and Inactivation in Streams: A Combined Experimental and Stochastic Modeling Approach.

    PubMed

    Drummond, Jennifer D; Davies-Colley, Robert J; Stott, Rebecca; Sukias, James P; Nagels, John W; Sharp, Alice; Packman, Aaron I

    2015-07-01

    Long-term survival of pathogenic microorganisms in streams enables long-distance disease transmission. In order to manage water-borne diseases more effectively we need to better predict how microbes behave in freshwater systems, particularly how they are transported downstream in rivers. Microbes continuously immobilize and resuspend during downstream transport owing to a variety of processes including gravitational settling, attachment to in-stream structures such as submerged macrophytes, and hyporheic exchange and filtration within underlying sediments. We developed a stochastic model to describe these microbial transport and retention processes in rivers that also accounts for microbial inactivation. We used the model to assess the transport, retention, and inactivation of Escherichia coli in a small stream and the underlying streambed sediments as measured from multitracer injection experiments. The results demonstrate that the combination of laboratory experiments on sediment cores, stream reach-scale tracer experiments, and multiscale stochastic modeling improves assessment of microbial transport in streams. This study (1) demonstrates new observations of microbial dynamics in streams with improved data quality than prior studies, (2) advances a stochastic modeling framework to include microbial inactivation processes that we observed to be important in these streams, and (3) synthesizes new and existing data to evaluate seasonal dynamics.

  15. Subcortical structure segmentation using probabilistic atlas priors

    NASA Astrophysics Data System (ADS)

    Gouttard, Sylvain; Styner, Martin; Joshi, Sarang; Smith, Rachel G.; Cody Hazlett, Heather; Gerig, Guido

    2007-03-01

    The segmentation of the subcortical structures of the brain is required for many forms of quantitative neuroanatomic analysis. The volumetric and shape parameters of structures such as lateral ventricles, putamen, caudate, hippocampus, pallidus and amygdala are employed to characterize a disease or its evolution. This paper presents a fully automatic segmentation of these structures via a non-rigid registration of a probabilistic atlas prior and alongside a comprehensive validation. Our approach is based on an unbiased diffeomorphic atlas with probabilistic spatial priors built from a training set of MR images with corresponding manual segmentations. The atlas building computes an average image along with transformation fields mapping each training case to the average image. These transformation fields are applied to the manually segmented structures of each case in order to obtain a probabilistic map on the atlas. When applying the atlas for automatic structural segmentation, an MR image is first intensity inhomogeneity corrected, skull stripped and intensity calibrated to the atlas. Then the atlas image is registered to the image using an affine followed by a deformable registration matching the gray level intensity. Finally, the registration transformation is applied to the probabilistic maps of each structures, which are then thresholded at 0.5 probability. Using manual segmentations for comparison, measures of volumetric differences show high correlation with our results. Furthermore, the dice coefficient, which quantifies the volumetric overlap, is higher than 62% for all structures and is close to 80% for basal ganglia. The intraclass correlation coefficient computed on these same datasets shows a good inter-method correlation of the volumetric measurements. Using a dataset of a single patient scanned 10 times on 5 different scanners, reliability is shown with a coefficient of variance of less than 2 percents over the whole dataset. Overall, these validation

  16. A model for evaluating stream temperature response to climate change scenarios in Wisconsin

    USGS Publications Warehouse

    Westenbroek, Stephen M.; Stewart, Jana S.; Buchwald, Cheryl A.; Mitro, Matthew G.; Lyons, John D.; Greb, Steven

    2010-01-01

    Global climate change is expected to alter temperature and flow regimes for streams in Wisconsin over the coming decades. Stream temperature will be influenced not only by the predicted increases in average air temperature, but also by changes in baseflow due to changes in precipitation patterns and amounts. In order to evaluate future stream temperature and flow regimes in Wisconsin, we have integrated two existing models in order to generate a water temperature time series at a regional scale for thousands of stream reaches where site-specific temperature observations do not exist. The approach uses the US Geological Survey (USGS) Soil-Water-Balance (SWB) model, along with a recalibrated version of an existing artificial neural network (ANN) stream temperature model. The ANN model simulates stream temperatures on the basis of landscape variables such as land use and soil type, and also includes climate variables such as air temperature and precipitation amounts. The existing ANN model includes a landscape variable called DARCY designed to reflect the potential for groundwater recharge in the contributing area for a stream segment. SWB tracks soil-moisture and potential recharge at a daily time step, providing a way to link changing climate patterns and precipitation amounts over time to baseflow volumes, and presumably to stream temperatures. The recalibrated ANN incorporates SWB-derived estimates of potential recharge to supplement the static estimates of groundwater flow potential derived from a topographically based model (DARCY). SWB and the recalibrated ANN will be supplied with climate drivers from a suite of general circulation models and emissions scenarios, enabling resource managers to evaluate possible changes in stream temperature regimes for Wisconsin.

  17. Stream Channelization: Conflict Between Ditchers, Conservationists

    ERIC Educational Resources Information Center

    Gillette, Robert

    1972-01-01

    Summarizes the argument between the advocates of stream straightening for flood control, drainage, and navigation, and those concerned with the maintenance of ecological communities and the aesthetic values of natural" streams. (AL)

  18. Stream Tables and Watershed Geomorphology Education.

    ERIC Educational Resources Information Center

    Lillquist, Karl D.; Kinner, Patricia W.

    2002-01-01

    Reviews copious stream tables and provides a watershed approach to stream table exercises. Results suggest that this approach to learning the concepts of fluvial geomorphology is effective. (Contains 39 references.) (DDR)

  19. Operation of a 1/10 scale mixed water incinerator air pollution control system

    SciTech Connect

    Burns, D.B.; Wong, A.; Walker, W.

    1996-08-01

    The Consolidated Incineration Facility (CIF) at the Savannah River Site is designed to treat solid and liquid RCRA hazardous and mixed wastes generated by site operations and clean-up activities. The technologies selected for use in the CIF air pollution control system (APCS) were based on reviews of existing commercial and DOE incinerators, on-site air pollution control experience, and recommendations from contracted consultants. In order to study the CIF APCS prior to operation, a 1/10 scale pilot facility, known as the Offgas Components Test Facility (OCTF) was constructed and has been in operation since late 1994. Its current mission is to demonstrate the design integrity of the CIF APCS and optimize equipment/instrument performance of the full scale production facility. Due to the nature of the wastes to be incinerated at the CIF, High Efficiency Particulate Air (HEPA) filters are used to remove hazardous and radioactive particulates from the exhaust gas stream before being released into the atmosphere. The HEPA filter change-out frequency has been a potential issue and was the first technical issue to be studied at the OCTF. Tests were conducted to evaluate the performance of HEPA filters under different operating conditions. These tests included evaluating the impact on HEPA life of scrubber operating parameters and the type of HEPA prefilter used. This pilot-scale testing demonstrated satisfactory HEPA filter life when using cleanable metal prefilters and high flows of steam and water in the offgas scrubber.

  20. An intake prior for the Bayesian analysis of plutonium and uranium exposures in an epidemiology study.

    PubMed

    Puncher, M; Birchall, A; Bull, R K

    2014-12-01

    In Bayesian inference, the initial knowledge regarding the value of a parameter, before additional data are considered, is represented as a prior probability distribution. This paper describes the derivation of a prior distribution of intake that was used for the Bayesian analysis of plutonium and uranium worker doses in a recent epidemiology study. The chosen distribution is log-normal with a geometric standard deviation of 6 and a median value that is derived for each worker based on the duration of the work history and the number of reported acute intakes. The median value is a function of the work history and a constant related to activity in air concentration, M, which is derived separately for uranium and plutonium. The value of M is based primarily on measurements of plutonium and uranium in air derived from historical personal air sampler (PAS) data. However, there is significant uncertainty on the value of M that results from paucity of PAS data and from extrapolating these measurements to actual intakes. This paper compares posterior and prior distributions of intake and investigates the sensitivity of the Bayesian analyses to the assumed value of M. It is found that varying M by a factor of 10 results in a much smaller factor of 2 variation in mean intake and lung dose for both plutonium and uranium. It is concluded that if a log-normal distribution is considered to adequately represent worker intakes, then the Bayesian posterior distribution of dose is relatively insensitive to the value assumed of M.

  1. A study of the effects of implementing agricultural best management practices and in-stream restoration on suspended sediment, stream habitat, and benthic macroinvertebrates at three stream sites in Surry County, North Carolina, 2004-2007-Lessons learned

    USGS Publications Warehouse

    Smith, Douglas G.; Ferrell, G.M.; Harned, Douglas A.; Cuffney, Thomas F.

    2011-01-01

    Creek site indicated a statistically significant (p<0.05) decrease in suspended-sediment discharge following in-stream restoration. Stream habitat characteristics were similar at the Bull Creek and Hogan Creek reaches. However, the Pauls Creek reach was distinguished from the other two sites by a lack of pools, greater bankfull widths, greater streamflow and velocity, and larger basin size. Historical changes in the stream channel in the vicinity of the Pauls Creek streamgage are evident in aerial photographs dating from 1936 to 2005 and could have contributed to stream-channel instability. The duration of this study likely was inadequate for detecting changes in stream habitat characteristics. Benthic macroinvertebrate assemblages differed by site and changed during the course of the study. Bull Creek, the best management practices site, stood out as the site having the poorest overall conditions and the greatest improvement in benthic macroinvertebrate communities during the study period. Richness and diversity metrics indicated that benthic macroinvertebrate community conditions at the Hogan Creek and Pauls Creek sites declined during the study, although the status was excellent based on the North Carolina Index of Biotic Integrity. Experiences encountered during this study exemplify the difficulties of attempting to assess the short-term effects of stream-improvement efforts on a watershed scale and, in particular, the difficulty of finding similar basins for a comparative study. Data interpretation was complicated by dry climatic conditions and unanticipated land disturbances that occurred during the study in each of the three study basins. For example, agricultural best management practices were implemented in the drainage basin of the control site prior to and during the study. An impoundment on Bull Creek upstream from the streamgaging station probably influenced water-quality conditions and streamflow. Road construction in the vicinity of the Pauls Creek site

  2. Putting Priors in Mixture Density Mercer Kernels

    NASA Technical Reports Server (NTRS)

    Srivastava, Ashok N.; Schumann, Johann; Fischer, Bernd

    2004-01-01

    This paper presents a new methodology for automatic knowledge driven data mining based on the theory of Mercer Kernels, which are highly nonlinear symmetric positive definite mappings from the original image space to a very high, possibly infinite dimensional feature space. We describe a new method called Mixture Density Mercer Kernels to learn kernel function directly from data, rather than using predefined kernels. These data adaptive kernels can en- code prior knowledge in the kernel using a Bayesian formulation, thus allowing for physical information to be encoded in the model. We compare the results with existing algorithms on data from the Sloan Digital Sky Survey (SDSS). The code for these experiments has been generated with the AUTOBAYES tool, which automatically generates efficient and documented C/C++ code from abstract statistical model specifications. The core of the system is a schema library which contains template for learning and knowledge discovery algorithms like different versions of EM, or numeric optimization methods like conjugate gradient methods. The template instantiation is supported by symbolic- algebraic computations, which allows AUTOBAYES to find closed-form solutions and, where possible, to integrate them into the code. The results show that the Mixture Density Mercer-Kernel described here outperforms tree-based classification in distinguishing high-redshift galaxies from low- redshift galaxies by approximately 16% on test data, bagged trees by approximately 7%, and bagged trees built on a much larger sample of data by approximately 2%.

  3. Prolonged Instability Prior to a Regime Shift

    PubMed Central

    Spanbauer, Trisha L.; Allen, Craig R.; Angeler, David G.; Eason, Tarsha; Fritz, Sherilyn C.; Garmestani, Ahjond S.; Nash, Kirsty L.; Stone, Jeffery R.

    2014-01-01

    Regime shifts are generally defined as the point of ‘abrupt’ change in the state of a system. However, a seemingly abrupt transition can be the product of a system reorganization that has been ongoing much longer than is evident in statistical analysis of a single component of the system. Using both univariate and multivariate statistical methods, we tested a long-term high-resolution paleoecological dataset with a known change in species assemblage for a regime shift. Analysis of this dataset with Fisher Information and multivariate time series modeling showed that there was a∼2000 year period of instability prior to the regime shift. This period of instability and the subsequent regime shift coincide with regional climate change, indicating that the system is undergoing extrinsic forcing. Paleoecological records offer a unique opportunity to test tools for the detection of thresholds and stable-states, and thus to examine the long-term stability of ecosystems over periods of multiple millennia. PMID:25280010

  4. Washing of waste prior to landfilling.

    PubMed

    Cossu, Raffaello; Lai, Tiziana

    2012-05-01

    The main impact produced by landfills is represented by the release of leachate emissions. Waste washing treatment has been investigated to evaluate its efficiency in reducing the waste leaching fraction prior to landfilling. The results of laboratory-scale washing tests applied to several significant residues from integrated management of solid waste are presented in this study, specifically: non-recyclable plastics from source separation, mechanical-biological treated municipal solid waste and a special waste, automotive shredded residues. Results obtained demonstrate that washing treatment contributes towards combating the environmental impacts of raw wastes. Accordingly, a leachate production model was applied, leading to the consideration that the concentrations of chemical oxygen demand (COD) and total Kjeldahl nitrogen (TKN), parameters of fundamental importance in the characterization of landfill leachate, from a landfill containing washed wastes, are comparable to those that would only be reached between 90 and 220years later in the presence of raw wastes. The findings obtained demonstrated that washing of waste may represent an effective means of reducing the leachable fraction resulting in a consequent decrease in landfill emissions. Further studies on pilot scale are needed to assess the potential for full-scale application of this treatment.

  5. Theoretical priors on modified growth parametrisations

    SciTech Connect

    Song, Yong-Seon; Hollenstein, Lukas; Caldera-Cabral, Gabriela; Koyama, Kazuya E-mail: Lukas.Hollenstein@unige.ch E-mail: Kazuya.Koyama@port.ac.uk

    2010-04-01

    Next generation surveys will observe the large-scale structure of the Universe with unprecedented accuracy. This will enable us to test the relationships between matter over-densities, the curvature perturbation and the Newtonian potential. Any large-distance modification of gravity or exotic nature of dark energy modifies these relationships as compared to those predicted in the standard smooth dark energy model based on General Relativity. In linear theory of structure growth such modifications are often parameterised by virtue of two functions of space and time that enter the relation of the curvature perturbation to, first, the matter over- density, and second, the Newtonian potential. We investigate the predictions for these functions in Brans-Dicke theory, clustering dark energy models and interacting dark energy models. We find that each theory has a distinct path in the parameter space of modified growth. Understanding these theoretical priors on the parameterisations of modified growth is essential to reveal the nature of cosmic acceleration with the help of upcoming observations of structure formation.

  6. Pitch perception prior to cortical maturation

    NASA Astrophysics Data System (ADS)

    Lau, Bonnie K.

    Pitch perception plays an important role in many complex auditory tasks including speech perception, music perception, and sound source segregation. Because of the protracted and extensive development of the human auditory cortex, pitch perception might be expected to mature, at least over the first few months of life. This dissertation investigates complex pitch perception in 3-month-olds, 7-month-olds and adults -- time points when the organization of the auditory pathway is distinctly different. Using an observer-based psychophysical procedure, a series of four studies were conducted to determine whether infants (1) discriminate the pitch of harmonic complex tones, (2) discriminate the pitch of unresolved harmonics, (3) discriminate the pitch of missing fundamental melodies, and (4) have comparable sensitivity to pitch and spectral changes as adult listeners. The stimuli used in these studies were harmonic complex tones, with energy missing at the fundamental frequency. Infants at both three and seven months of age discriminated the pitch of missing fundamental complexes composed of resolved and unresolved harmonics as well as missing fundamental melodies, demonstrating perception of complex pitch by three months of age. More surprisingly, infants in both age groups had lower pitch and spectral discrimination thresholds than adult listeners. Furthermore, no differences in performance on any of the tasks presented were observed between infants at three and seven months of age. These results suggest that subcortical processing is not only sufficient to support pitch perception prior to cortical maturation, but provides adult-like sensitivity to pitch by three months.

  7. Capitation payments based on prior hospitalizations.

    PubMed

    van Vliet, R C; van de Ven, W P

    1993-07-01

    In many countries the concept of capitating health care insurers is receiving increasing attention. In a competitive environment, capitation should induce insurers to concentrate more on cost containment instead of indulging in risk selection. The necessary premium-replacing capitation payments should account for predictable variations in annual per-person health care expenditures as far as these are related to health status. Various studies have shown that crude capitation models based on e.g. age, sex and place of residence, do not reflect expected costs accurately. This implies inefficient pricing possibly leading to risk selection and windfall profits or losses for insurers, thereby undermining the objectives of a capitation system. Using Dutch micro data on some 200,000 individuals, this article stimulates various alternative capitation models based on, among others, diagnostic information from previous hospitalizations. Results suggest that the problems of both risk selection and windfall profits/losses may be mitigated substantially by using this type of information together with data on prior costs. These results are not only relevant for situations where competing insurers are capitated, as intended in the Netherlands, but also when providers are capitated, as in the UK, or when HMOs are capitated, as in the US.

  8. Cathodic ARC surface cleaning prior to brazing

    SciTech Connect

    Dave, V. R.; Hollis, K. J.; Castro, R. G.; Smith, F. M.; Javernick, D. A.

    2002-01-01

    Surface cleanliness is one the critical process variables in vacuum furnace brazing operations. For a large number of metallic components, cleaning is usually accomplished either by water-based alkali cleaning, but may also involve acid etching or solvent cleaning / rinsing. Nickel plating may also be necessary to ensure proper wetting. All of these cleaning or plating technologies have associated waste disposal issues, and this article explores an alternative cleaning process that generates minimal waste. Cathodic arc, or reserve polarity, is well known for welding of materials with tenacious oxide layers such as aluminum alloys. In this work the reverse polarity effect is used to clean austenitic stainless steel substrates prior to brazing with Ag-28%Cu. This cleaning process is compared to acid pickling and is shown to produce similar wetting behavior as measured by dynamic contact angle experiments. Additionally, dynamic contact angle measurements with water drops are conducted to show that cathodic arc cleaning can remove organic contaminants as well. The process does have its limitations however, and alloys with high titanium and aluminum content such as nickel-based superalloys may still require plating to ensure adequate wetting.

  9. Washing of waste prior to landfilling.

    PubMed

    Cossu, Raffaello; Lai, Tiziana

    2012-05-01

    The main impact produced by landfills is represented by the release of leachate emissions. Waste washing treatment has been investigated to evaluate its efficiency in reducing the waste leaching fraction prior to landfilling. The results of laboratory-scale washing tests applied to several significant residues from integrated management of solid waste are presented in this study, specifically: non-recyclable plastics from source separation, mechanical-biological treated municipal solid waste and a special waste, automotive shredded residues. Results obtained demonstrate that washing treatment contributes towards combating the environmental impacts of raw wastes. Accordingly, a leachate production model was applied, leading to the consideration that the concentrations of chemical oxygen demand (COD) and total Kjeldahl nitrogen (TKN), parameters of fundamental importance in the characterization of landfill leachate, from a landfill containing washed wastes, are comparable to those that would only be reached between 90 and 220years later in the presence of raw wastes. The findings obtained demonstrated that washing of waste may represent an effective means of reducing the leachable fraction resulting in a consequent decrease in landfill emissions. Further studies on pilot scale are needed to assess the potential for full-scale application of this treatment. PMID:22245736

  10. Stream Gauges and Satellite Measurements

    NASA Astrophysics Data System (ADS)

    Alsdorf, D. E.

    2010-12-01

    Satellite measurements should not be viewed as a replacement for stream gauges. However, occasionally it is suggested that because satellite-based measurements can provide river discharge, a motivation for satellite approaches is an increasing lack of stream gauges. This is an argument for more stream gauges, but not necessarily for satellite measurements. Rather, in-situ and spaceborne methods of estimating discharge are complementary. Stream gauges provide frequent measurements at one point in the river reach whereas satellites have the potential to measure throughout all reaches but at orbital repeat intervals of days to weeks. The Surface Water and Ocean Topography satellite mission (SWOT) is an opportunity to further develop these complements. The motivation for SWOT, and indeed for any satellite based method of estimating discharge, should not be as a replacement for stream gauges. Scientific and application uses should motivate the measurements. For example, understanding floods with their dynamic water surfaces are best sampled from remote platforms that provide water surface elevations throughout the floodwave. As another example, today’s water and energy balance models are giving outputs at increasing spatial resolution and are making use of water surface elevations throughout the modeled basin. These models require a similar resolution in the calibrating and validating observations. We should also be aware of practical limitations. In addition to providing spatially distributed hydrodynamic measurements on rivers, SWOT will be able to measure storage changes in the estimated 30 million lakes in the world that are larger than a hectare. Knowing the storage changes in these lakes is especially important in certain regions such as the Arctic but gauging even a small fraction of these is impractical. Another motivator for satellite methods is that even in the presence of stream gauges, discharge data is not always well shared throughout all countries

  11. Reconciling geochemical and physical tracers of groundwater-stream interactions

    NASA Astrophysics Data System (ADS)

    Hofmann, H.; Cartwright, I.; Gilfedder, B.; Unland, N.; Atkinson, A.; Yu, M.

    2011-12-01

    quantifying the input of water to the streams from reservoirs such as the river banks and the unsaturated zone and to understand the impacts of sampling prior to or following flood peaks on the stream geochemistry. These studies provide a more robust understanding of groundwater-surface water interaction in these catchments that goes to reconciling the results from different types of studies.

  12. A stream-based methane monitoring approach for evaluating groundwater impacts associated with unconventional gas development.

    PubMed

    Heilweil, Victor M; Stolp, Bert J; Kimball, Briant A; Susong, David D; Marston, Thomas M; Gardner, Philip M

    2013-01-01

    Gaining streams can provide an integrated signal of relatively large groundwater capture areas. In contrast to the point-specific nature of monitoring wells, gaining streams coalesce multiple flow paths. Impacts on groundwater quality from unconventional gas development may be evaluated at the watershed scale by the sampling of dissolved methane (CH4 ) along such streams. This paper describes a method for using stream CH4 concentrations, along with measurements of groundwater inflow and gas transfer velocity interpreted by 1-D stream transport modeling, to determine groundwater methane fluxes. While dissolved ionic tracers remain in the stream for long distances, the persistence of methane is not well documented. To test this method and evaluate CH4 persistence in a stream, a combined bromide (Br) and CH4 tracer injection was conducted on Nine-Mile Creek, a gaining stream in a gas development area in central Utah. A 35% gain in streamflow was determined from dilution of the Br tracer. The injected CH4 resulted in a fivefold increase in stream CH4 immediately below the injection site. CH4 and δ(13) CCH4 sampling showed it was not immediately lost to the atmosphere, but remained in the stream for more than 2000 m. A 1-D stream transport model simulating the decline in CH4 yielded an apparent gas transfer velocity of 4.5 m/d, describing the rate of loss to the atmosphere (possibly including some microbial consumption). The transport model was then calibrated to background stream CH4 in Nine-Mile Creek (prior to CH4 injection) in order to evaluate groundwater CH4 contributions. The total estimated CH4 load discharging to the stream along the study reach was 190 g/d, although using geochemical fingerprinting to determine its source was beyond the scope of the current study. This demonstrates the utility of stream-gas sampling as a reconnaissance tool for evaluating both natural and anthropogenic CH4 leakage from gas reservoirs into groundwater and surface water.

  13. A model for evaluating stream temperature response to climate change in Wisconsin

    USGS Publications Warehouse

    Stewart, Jana S.; Westenbroek, Stephen M.; Mitro, Matthew G.; Lyons, John D.; Kammel, Leah E.; Buchwald, Cheryl A.

    2015-01-01

    Integrating the SWB Model with the ANN Model provided a mechanism by which downscaled global or regional climate model results could be used to estimate the potential effects of climate change on future stream temperature on a daily time step. To address future climate scenarios, statistically downscaled air temperature and precipitation projections from 10 GCMs and 2 time periods were used with the SWB-ANNv1 Model to project future stream temperature. Projections of future stream temperatures at mid- (2046–65) and late- (2081–2100) 21st century showed the July mean water temperature increasing for all stream segments with about 80 percent of stream kilometers increasing by 1 to 2 degrees Celsius (°C) by mid-century and about 99 percent increasing by 1 to 3 °C by late-century. Projected changes in stream temperatures also affected changes in thermal classes with a loss in the total amount of cold-water, cold-transition, and warm-transition thermal habitat and a gain in warm-water and very warm thermal habitat for both mid- and late-21st century time periods. The greatest losses occurred for cold-water streams and the greatest gains for warm-water streams, with a contraction of cold-water streams in the Driftless Area of western and southern Wisconsin and an expansion of warm-water streams across northern Wisconsin. Results of this study suggest that such changes will affect the composition of fish assemblages, with a loss of suitable habitat for cold-water fishes and gain in suitable habitat for warm-water fishes. In the end, these projected changes in thermal habitat attributable to climate may result in a net loss of fisheries, because many warm-water species may be unable to colonize habitats formerly occupied by cold-water species because of other habitat limitations (e.g., stream size, gradient). Although projected stream temperatures may vary greatly, depending on the emissions scenario and models used, the results presented in this report represent one

  14. Maximizing Resource Utilization in Video Streaming Systems

    ERIC Educational Resources Information Center

    Alsmirat, Mohammad Abdullah

    2013-01-01

    Video streaming has recently grown dramatically in popularity over the Internet, Cable TV, and wire-less networks. Because of the resource demanding nature of video streaming applications, maximizing resource utilization in any video streaming system is a key factor to increase the scalability and decrease the cost of the system. Resources to…

  15. The Stream Table in Physical Geography Instruction.

    ERIC Educational Resources Information Center

    Wikle, Thomas A.; Lightfoot, Dale R.

    1997-01-01

    Outlines a number of activities to be conducted with a stream table (large wooden box filled with sediment and designed for water to pass through) in class. Activities illustrate such fluvial processes as stream meandering, erosion, transportation, and deposition. Includes a diagram for constructing a stream table. (MJP)

  16. Olefin Recovery from Chemical Industry Waste Streams

    SciTech Connect

    A.R. Da Costa; R. Daniels; A. Jariwala; Z. He; A. Morisato; I. Pinnau; J.G. Wijmans

    2003-11-21

    The objective of this project was to develop a membrane process to separate olefins from paraffins in waste gas streams as an alternative to flaring or distillation. Flaring these streams wastes their chemical feedstock value; distillation is energy and capital cost intensive, particularly for small waste streams.

  17. Prior Clues of Internal Activity on Pluto

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-08-01

    Singer and Stern's theories of internal activity, but raise new questions about the nature of that activity! As data from New Horizons keeps streaming in (in fact, atmospheric data from the Alice instrument is expected to pin down the atmospheric loss rate very soon), we can hope to continue to piece this picture together. Citation: Kelsi N. Singer and S. Alan Stern 2015 ApJ, 808, L50.

  18. Slow Climate Velocities in Mountain Streams Impart Thermal Resistance to Cold-Water Refugia Across the West

    NASA Astrophysics Data System (ADS)

    Isaak, D.; Young, M.; Luce, C.; Hostetler, S.; Wenger, S. J.; Peterson, E.; Ver Hoef, J.

    2015-12-01

    Mountain streams provide important headwater refugia for native fish, amphibians, and other cold-water fauna globally. Although the well documented existence of such refugia indicates some level of resistance to ongoing environmental change, stream warming associated with climate change raises questions about their future persistence. Moreover, evidence exists that air temperatures are warming faster at higher elevations, and some stream temperature models predict that cold streams associated with snowmelt hydrologies will be most sensitive to air temperature increases (i.e. high ratio of stream Δ˚C:air Δ˚C). Here, we estimate stream sensitivities to climate forcing using long-term monitoring records from 927 sites across the topographically complex northwestern U.S. Sensitivity values are combined with high-resolution NorWeST stream temperature scenarios (website: http://www.fs.fed.us/rm/boise/AWAE/projects/NorWeST.html) to map climate velocities at 1 kilometer resolution throughout the 450,000 stream kilometers in the regional network. Our results suggest that cold mountain streams are often 'double buffered' against the thermal effects of climate change due to low sensitivities (0.3ºC/ºC) and steep gradients, which translated to very slow climate velocities (<0.35 km/decade for streams >3% slope) from 1968-2011 when air temperatures warmed at the rate of 0.2ºC/decade. Alternative scenarios based on aggressive air temperature warming rates (2x historical rates) and higher sensitivity values of cold streams suggests velocities will remain low in mountain streams due to the dominant effects of steep channel slope and strong local temperature gradients. These results reinforce earlier predictions from high-resolution species distribution models that show which watersheds are most likely to host resilient native trout populations across the West later this century (Climate Shield project website: http://www.fs

  19. Simulation of future stream alkalinity under changing deposition and climate scenarios.

    PubMed

    Welsch, Daniel L; Cosby, B Jack; Hornberger, George M

    2006-08-31

    Models of soil and stream water acidification have typically been applied under scenarios of changing acidic deposition, however, climate change is usually ignored. Soil air CO2 concentrations have potential to increase as climate warms and becomes wetter, thus affecting soil and stream water chemistry by initially increasing stream alkalinity at the expense of reducing base saturation levels on soil exchange sites. We simulate this change by applying a series of physically based coupled models capable of predicting soil air CO2 and stream water chemistry. We predict daily stream water alkalinity for a small catchment in the Virginia Blue Ridge for 60 years into the future given stochastically generated daily climate values. This is done for nine different combinations of climate and deposition. The scenarios for both climate and deposition include a static scenario, a scenario of gradual change, and a scenario of abrupt change. We find that stream water alkalinity continues to decline for all scenarios (average decrease of 14.4 microeq L-1) except where climate is gradually warming and becoming more moist (average increase of 13 microeq L-1). In all other scenarios, base cation removal from catchment soils is responsible for limited alkalinity increase resulting from climate change. This has implications given the extent that acidification models are used to establish policy and legislation concerning deposition and emissions.

  20. Simulation of future stream alkalinity under changing deposition and climate scenarios.

    PubMed

    Welsch, Daniel L; Cosby, B Jack; Hornberger, George M

    2006-08-31

    Models of soil and stream water acidification have typically been applied under scenarios of changing acidic deposition, however, climate change is usually ignored. Soil air CO2 concentrations have potential to increase as climate warms and becomes wetter, thus affecting soil and stream water chemistry by initially increasing stream alkalinity at the expense of reducing base saturation levels on soil exchange sites. We simulate this change by applying a series of physically based coupled models capable of predicting soil air CO2 and stream water chemistry. We predict daily stream water alkalinity for a small catchment in the Virginia Blue Ridge for 60 years into the future given stochastically generated daily climate values. This is done for nine different combinations of climate and deposition. The scenarios for both climate and deposition include a static scenario, a scenario of gradual change, and a scenario of abrupt change. We find that stream water alkalinity continues to decline for all scenarios (average decrease of 14.4 microeq L-1) except where climate is gradually warming and becoming more moist (average increase of 13 microeq L-1). In all other scenarios, base cation removal from catchment soils is responsible for limited alkalinity increase resulting from climate change. This has implications given the extent that acidification models are used to establish policy and legislation concerning deposition and emissions. PMID:16600331

  1. Multi-Scale observation of time-variable surface and subsurface interactions of an intermittent urban stream

    NASA Astrophysics Data System (ADS)

    Cain, Molly; Ward, Adam; Schmadel, Noah; Hixson, Jase

    2016-04-01

    Our current understanding of stream-hyporheic tansport is primarily based on field observations conducted during baseflow conditions in perennial streams, with few studies considering time-variable stream-aquifer interactions during storm events. During the summer of 2015, we completed 21 sets of four slug injections prior to, during and after storm events in an urban stream. These data allow for the comparison of temporal heterogeneity in transport processes when the stream was intermittent, or consisting of spatially disconnected pools of water with subsurface flow in between, and when there was continuous surface flow during and after rainfall. The injections were performed in three adjacent 50-meter study reaches, enabling the additional comparison of spatial heterogeneity in transport processes. Reach-scale data demonstrate apparent trends with discharge in both short-term storage (commonly "transient storage") and long-term storage (commonly "channel water balance"). Preliminary results indicate the interaction of changing advective timescales for tracer studies are an important control on inferred process dynamics. Furthermore, observations of stream connectivity inform time-variable transport processes within intermittent streams. Comparison of short-term and long-term storage at varying discharge demonstrates opportunities and challenges for interpretation of multi-scale solute tracer data along the stream-hyporheic-riparian-floodplain continuum in intermittent streams.

  2. Thermal loading of natural streams

    USGS Publications Warehouse

    Jackman, Alan P.; Yotsukura, Nobuhiro

    1977-01-01

    The impact of thermal loading on the temperature regime of natural streams is investigated by mathematical models, which describe both transport (convection-diffusion) and decay (surface dissipation) of waste heat over 1-hour or shorter time intervals. The models are derived from the principle of conservation of thermal energy for application to one- and two-dimensional spaces. The basic concept in these models is to separate water temperature into two parts, (1) excess temperature due to thermal loading and (2) natural (ambient) temperature. This separation allows excess temperature to be calculated from the models without incoming radiation data. Natural temperature may either be measured in prototypes or calculated from the model. If use is made of the model, however, incoming radiation is required as input data. Comparison of observed and calculated temperatures in seven natural streams shows that the models are capable of predicting transient temperature regimes satisfactorily in most cases. (Woodard-USGS)

  3. Metamers of the ventral stream

    PubMed Central

    Freeman, Jeremy; Simoncelli, Eero P.

    2011-01-01

    The human capacity to recognize complex visual patterns emerges in a sequence of brain areas known as the ventral stream, beginning with primary visual cortex (V1). We develop a population model for mid-ventral processing, in which non-linear combinations of V1 responses are averaged within receptive fields that grow with eccentricity. To test the model, we generate novel forms of visual metamers — stimuli that differ physically, but look the same. We develop a behavioral protocol that uses metameric stimuli to estimate the receptive field sizes in which the model features are represented. Because receptive field sizes change along the ventral stream, the behavioral results can identify the visual area corresponding to the representation. Measurements in human observers implicate V2, providing a new functional account of this area. The model explains deficits of peripheral vision known as “crowding”, and provides a quantitative framework for assessing the capabilities of everyday vision. PMID:21841776

  4. Streaming visualization for collaborative environments.

    SciTech Connect

    Hereld, M.; Olson, E.; Papka, M. E.; Uram, T. D.

    2008-01-01

    Connecting expensive and scarce visual data analysis resources to end-users is a major challenge today. We describe a flexible mechanism for meeting this challenge based on commodity compression technologies for streaming video. The advantages of this approach include simplified application development, access to generic client components for viewing, and simplified incorporation of improved codecs as they become available. In this paper we report newly acquired experimental results for two different applications being developed to exploit this approach and test its merits. One is based on a new plugin for ParaView that adds video streaming cleanly and transparently to existing applications. The other is a custom volume rendering application with new remote capabilities. Using typical datasets under realistic conditions, we find the performance for both is satisfactory.

  5. Streaming visualization for collaborative environments

    NASA Astrophysics Data System (ADS)

    Hereld, M.; Olson, E.; Papka, M. E.; Uram, T. D.

    2008-07-01

    Connecting expensive and scarce visual data analysis resources to end-users is a major challenge today. We describe a flexible mechanism for meeting this challenge based on commodity compression technologies for streaming video. The advantages of this approach include simplified application development, access to generic client components for viewing, and simplified incorporation of improved codecs as they become available. In this paper we report newly acquired experimental results for two different applications being developed to exploit this approach and test its merits. One is based on a new plugin for ParaView that adds video streaming cleanly and transparently to existing applications. The other is a custom volume rendering application with new remote capabilities. Using typical datasets under realistic conditions, we find the performance for both is satisfactory.

  6. Where Did All the Streams Go? Effects of Urbanization on Hydrologic Permanence of Headwater Streams

    EPA Science Inventory

    Headwater streams represent a majority (up to 70%) of the stream length in the United States; however, these small streams are often piped or filled to accommodate residential, commercial, and industrial development. Legal protection of headwater streams under the Clean Water Ac...

  7. Academic Self-Concepts in Ability Streams: Considering Domain Specificity and Same-Stream Peers

    ERIC Educational Resources Information Center

    Liem, Gregory Arief D.; McInerney, Dennis M.; Yeung, Alexander S.

    2015-01-01

    The study examined the relations between academic achievement and self-concepts in a sample of 1,067 seventh-grade students from 3 core ability streams in Singapore secondary education. Although between-stream differences in achievement were large, between-stream differences in academic self-concepts were negligible. Within each stream, levels of…

  8. Statistical modeling of daily and subdaily stream temperatures: Application to the Methow River Basin, Washington

    NASA Astrophysics Data System (ADS)

    Caldwell, R. J.; Gangopadhyay, S.; Bountry, J.; Lai, Y.; Elsner, M. M.

    2013-07-01

    Management of water temperatures in the Columbia River Basin (Washington) is critical because water projects have substantially altered the habitat of Endangered Species Act listed species, such as salmon, throughout the basin. This is most important in tributaries to the Columbia, such as the Methow River, where the spawning and rearing life stages of these cold water fishes occurs. Climate change projections generally predict increasing air temperatures across the western United States, with less confidence regarding shifts in precipitation. As air temperatures rise, we anticipate a corresponding increase in water temperatures, which may alter the timing and availability of habitat for fish reproduction and growth. To assess the impact of future climate change in the Methow River, we couple historical climate and future climate projections with a statistical modeling framework to predict daily mean stream temperatures. A K-nearest neighbor algorithm is also employed to: (i) adjust the climate projections for biases compared to the observed record and (ii) provide a reference for performing spatiotemporal disaggregation in future hydraulic modeling of stream habitat. The statistical models indicate the primary drivers of stream temperature are maximum and minimum air temperature and stream flow and show reasonable skill in predictability. When compared to the historical reference time period of 1916-2006, we conclude that increases in stream temperature are expected to occur at each subsequent time horizon representative of the year 2020, 2040, and 2080, with an increase of 0.8 ± 1.9°C by the year 2080.

  9. 13 CFR 305.14 - Occupancy prior to completion.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... COMMERCE PUBLIC WORKS AND ECONOMIC DEVELOPMENT INVESTMENTS Requirements for Approved Projects § 305.14 Occupancy prior to completion. Occupancy of any part of the Project prior to final acceptance is entirely...

  10. 13 CFR 305.14 - Occupancy prior to completion.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... COMMERCE PUBLIC WORKS AND ECONOMIC DEVELOPMENT INVESTMENTS Requirements for Approved Projects § 305.14 Occupancy prior to completion. Occupancy of any part of the Project prior to final acceptance is entirely...

  11. 29 CFR 18.613 - Prior statements of witnesses.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... OFFICE OF ADMINISTRATIVE LAW JUDGES Rules of Evidence Witnesses § 18.613 Prior statements of witnesses.... (b) Extrinsic evidence of prior inconsistent statement of witness. Extrinsic evidence of a...

  12. Scaling relations for galaxies prior to reionization

    SciTech Connect

    Chen, Pengfei; Norman, Michael L.; Xu, Hao; Wise, John H.; O'Shea, Brian W. E-mail: mlnorman@ucsd.edu E-mail: jwise@gatech.edu

    2014-11-10

    The first galaxies in the universe are the building blocks of all observed galaxies. We present scaling relations for galaxies forming at redshifts z ≥ 15 when reionization is just beginning. We utilize the 'Rarepeak' cosmological radiation hydrodynamics simulation that captures the complete star formation history in over 3300 galaxies, starting with massive Population III stars that form in dark matter halos as small as ∼10{sup 6} M {sub ☉}. We make various correlations between the bulk halo quantities, such as virial, gas, and stellar masses and metallicities and their respective accretion rates, quantifying a variety of properties of the first galaxies up to halo masses of 10{sup 9} M {sub ☉}. Galaxy formation is not solely relegated to atomic cooling halos with virial temperatures greater than 10{sup 4} K, where we find a dichotomy in galaxy properties between halos above and below this critical mass scale. Halos below the atomic cooling limit have a stellar mass-halo mass relationship log M {sub *} ≅ 3.5 + 1.3log (M {sub vir}/10{sup 7} M {sub ☉}). We find a non-monotonic relationship between metallicity and halo mass for the smallest galaxies. Their initial star formation events enrich the interstellar medium and subsequent star formation to a median of 10{sup –2} Z {sub ☉} and 10{sup –1.5} Z {sub ☉}, respectively, in halos of total mass 10{sup 7} M {sub ☉}, which is then diluted by metal-poor inflows well beyond Population III pre-enrichment levels of 10{sup –3.5} Z {sub ☉}. The scaling relations presented here can be employed in models of reionization, galaxy formation, and chemical evolution in order to consider these galaxies forming prior to reionization.

  13. Fitting orbits to tidal streams

    NASA Astrophysics Data System (ADS)

    Binney, James

    2008-05-01

    Recent years have seen the discovery of many tidal streams through the Galaxy. Relatively straightforward observations of a stream allow one to deduce three phase-space coordinates of an orbit. An algorithm is presented that reconstructs the missing phase-space coordinates from these data. The reconstruction starts from assumed values of the Galactic potential and a distance to one point on the orbit, but with noise-free data the condition that energy be conserved on the orbit enables one to reject incorrect assumptions. The performance of the algorithm is investigated when errors are added to the input data that are comparable to those in published data for the streams of Pal 5. It is found that the algorithm returns distances and proper motions that are accurate to of the order of 1 per cent, and enables one to reject quite resonable but incorrect trial potentials. In practical applications, it will be important to minimize errors in the imput data, and there is considerable scope for doing this.

  14. Interplanetary stream magnetism - Kinematic effects

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Barouch, E.

    1976-01-01

    The particle density and the magnetic-field intensity and direction are calculated for volume elements of the solar wind as a function of the initial magnetic-field direction and the initial speed gradient. It is assumed that the velocity is constant and radial. These assumptions are approximately valid between about 0.1 and 1.0 AU for many streams. Time profiles of the particle density, field intensity, and velocity are calculated for corotating streams, neglecting effects of pressure gradients. The compression and rarefaction of the magnetic field depend sensitively on the initial field direction. By averaging over a typical stream, it is found that the average radial field intensity is inversely proportional to the square of the heliocentric distance, whereas the average intensity in the direction of the planets' motion does not vary in a simple way, consistent with deep space observations. Changes of field direction may be very large, depending on the initial angle; but when the initial angle at 0.1 AU is such that the base of the field line corotates with the sun, the spiral angle is the preferred direction at 1 AU. The theory is also applicable to nonstationary flows.

  15. Air Pollution

    MedlinePlus

    ... tobacco smoke. How is air pollution linked to climate change? While climate change is a global process, it ... ozone levels are also a concern. Impacts of Climate Change on Human Health in the United States: A ...

  16. Air Apparent.

    ERIC Educational Resources Information Center

    Harbster, David A.

    1988-01-01

    Explains the principle upon which a barometer operates. Describes how to construct two barometric devices for use in the classroom that show air's changing pressure. Cites some conditions for predicting weather. (RT)

  17. Stream biogeochemical and suspended sediment responses to permafrost degradation in stream banks in Taylor Valley, Antarctica

    NASA Astrophysics Data System (ADS)

    Gooseff, Michael N.; Van Horn, David; Sudman, Zachary; McKnight, Diane M.; Welch, Kathleene A.; Lyons, William B.

    2016-03-01

    Stream channels in the McMurdo Dry Valleys are characteristically wide, incised, and stable. At typical flows, streams occupy a fraction of the oversized channels, providing habitat for algal mats. In January 2012, we discovered substantial channel erosion and subsurface thermomechanical erosion undercutting banks of the Crescent Stream. We sampled stream water along the impacted reach and compared concentrations of solutes to the long-term data from this stream ( ˜ 20 years of monitoring). Thermokarst-impacted stream water demonstrated higher electrical conductivity, and concentrations of chloride, sulfate, sodium, and nitrate than the long-term medians. These results suggest that this mode of lateral permafrost degradation may substantially impact stream solute loads and potentially fertilize stream and lake ecosystems. The potential for sediment to scour or bury stream algal mats is yet to be determined, though it may offset impacts of associated increased nutrient loads to streams.

  18. Urban air

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    Air pollution and the risk of potential health effects are not sufficiently convincing reasons for people to stop driving their cars, according to a study by the Population Reference Bureau (PRB) released on November 18.While sufficient levels of suspended particulate matter, carbon monoxide, and lead can present health concerns, the study found that many people surveyed for the study were not convinced of the clear linkage between air pollution and health.

  19. Carbon fiber composite molecular sieve electrically regenerable air filter media

    DOEpatents

    Wilson, K.A.; Burchell, T.D.; Judkins, R.R.

    1998-10-27

    An electrically regenerable gas filter system includes a carbon fiber composite molecular sieve (CFCMS) filter medium. After a separate medium-efficiency pre-filter removes particulate from the supply air stream, the CFCMS filter sorbs gaseous air pollutants before the air is recirculated to the space. When saturated, the CFCMS media is regenerated utilizing a low-voltage current that is caused to pass through the filter medium. 3 figs.

  20. Recognition of Prior and Experiential Learning in European Universities

    ERIC Educational Resources Information Center

    Valk, Aune

    2009-01-01

    This paper focuses on the state of the art for recognition of prior experiential learning in European universities. Although recognition of prior learning and prior experiential learning have been officially stated as being important aims by national ministers of education in their Bologna Process communiques, implementation in the majority of…

  1. How Prior Knowledge Affects Word Identification and Comprehension

    ERIC Educational Resources Information Center

    Priebe, Sarah J.; Keenan, Janice M.; Miller, Amanda C.

    2012-01-01

    While prior knowledge of a passage topic is known to facilitate comprehension, little is known about how it affects word identification. We examined oral reading errors in good and poor readers when reading a passage where they either had prior knowledge of the passage topic or did not. Children who had prior knowledge of the topic were matched on…

  2. Community of Priors: A Bayesian Approach to Consensus Building

    ERIC Educational Resources Information Center

    Hara, Motoaki

    2010-01-01

    Despite having drawn from empirical evidence and cumulative prior expertise in the formulation of research questions as well as study design, each study is treated as a stand-alone product rather than positioned within a sequence of cumulative evidence. While results of prior studies are typically cited within the body of prior literature review,…

  3. Towards Flexible Exascale Stream Processing System Simulation

    SciTech Connect

    Li, Cheng-Hong; Nair, Ravi; Ohba, Noboyuki; Shvadron, Uzi; Zaks, Ayal; Schenfeld, Eugen

    2012-01-01

    Stream processing is an important emerging computational model for performing complex operations on and across multi-source, high-volume, unpredictable dataflows. We present Flow, a platform for parallel and distributed stream processing system simulation that provides a flexible modeling environment for analyzing stream processing applications. The Flow stream processing system simulator is a high-performance, scalable simulator that automatically parallelizes chunks of the model space and incurs near-zero synchronization overhead for acyclic stream application graphs. We show promising parallel and distributed event rates exceeding 149 million events per second on a cluster with 512 processor cores.

  4. Process for recovering organic vapors from air

    DOEpatents

    Baker, Richard W.

    1985-01-01

    A process for recovering and concentrating organic vapor from a feed stream of air having an organic vapor content of no more than 20,000 ppm by volume. A thin semipermeable membrane is provided which has a feed side and a permeate side, a selectivity for organic vapor over air of at least 50, as measured by the ratio of organic vapor permeability to nitrogen permeability, and a permeability of organic vapor of at least 3.times.10.sup.-7 cm.sup.3 (STP) cm/cm.sup.2 sec.cm Hg. The feed stream is passed across the feed side of the thin semipermeable membrane while providing a pressure on the permeate side which is lower than the feed side by creating a partial vacuum on the permeate side so that organic vapor passes preferentially through the membrane to form an organic vapor depleted air stream on the feed side and an organic vapor enriched stream on the permeate side. The organic vapor which has passed through the membrane is compressed and condensed to recover the vapor as a liquid.

  5. Shotgun metagenomic data streams: surfing without fear

    SciTech Connect

    Berendzen, Joel R

    2010-12-06

    Timely information about bio-threat prevalence, consequence, propagation, attribution, and mitigation is needed to support decision-making, both routinely and in a crisis. One DNA sequencer can stream 25 Gbp of information per day, but sampling strategies and analysis techniques are needed to turn raw sequencing power into actionable knowledge. Shotgun metagenomics can enable biosurveillance at the level of a single city, hospital, or airplane. Metagenomics characterizes viruses and bacteria from complex environments such as soil, air filters, or sewage. Unlike targeted-primer-based sequencing, shotgun methods are not blind to sequences that are truly novel, and they can measure absolute prevalence. Shotgun metagenomic sampling can be non-invasive, efficient, and inexpensive while being informative. We have developed analysis techniques for shotgun metagenomic sequencing that rely upon phylogenetic signature patterns. They work by indexing local sequence patterns in a manner similar to web search engines. Our methods are laptop-fast and favorable scaling properties ensure they will be sustainable as sequencing methods grow. We show examples of application to soil metagenomic samples.

  6. Premixed turbulent combustion to opposed streams

    SciTech Connect

    Kostiuk, L.W.; Cheng, R.K.

    1992-03-01

    Premixed turbulent combustion in opposed streams has been studied experimentally by the use of two component laser doppler aneomometry. This flow geometry is part of a class of stagnating flows used to study turbulent combustion in recent years. It does not involve any surface near the flames because of the flow symmetry thus circumventing many of the effects of flame surface interaction. The mean non-reacting flow is found to be self-similar for all the conditions studied in this and the stagnation plate configuration. A homogeneous region of plane straining is produced in the vicinity of the stagnation and there is a strong interaction between the turbulence in the flow and the mean straining which can increase the rms velocity as the flow stagnates. The reacting flow fields are found to be symmetric about the free stagnation point. The traverses of mean axial velocity in the stagnation streamlines for reaction flows are not dramatically different from the non-reaction flows. These results differ from turbulent combustion experiments where the flow is stagnated by a flat plate. The extinction limits was studied for propane:air mixtures. 11 refs.

  7. Global perspectives on the urban stream syndrome

    USGS Publications Warehouse

    Roy, Allison; Booth, Derek B.; Capps, Krista A.; Smith, Benjamin

    2016-01-01

    Urban streams commonly express degraded physical, chemical, and biological conditions that have been collectively termed the “urban stream syndrome”. The description of the syndrome highlights the broad similarities among these streams relative to their less-impaired counterparts. Awareness of these commonalities has fostered rapid improvements in the management of urban stormwater for the protection of downstream watercourses, but the focus on the similarities among urban streams has obscured meaningful differences among them. Key drivers of stream responses to urbanization can vary greatly among climatological and physiographic regions of the globe, and the differences can be manifested in individual stream channels even through the homogenizing veneer of urban development. We provide examples of differences in natural hydrologic and geologic settings (within similar regions) that can result in different mechanisms of stream ecosystem response to urbanization and, as such, should lead to different management approaches. The idea that all urban streams can be cured using the same treatment is simplistic, but overemphasizing the tremendous differences among natural (or human-altered) systems also can paralyze management. Thoughtful integration of work that recognizes the commonalities of the urban stream syndrome across the globe has benefitted urban stream management. Now we call for a more nuanced understanding of the regional, subregional, and local attributes of any given urban stream and its watershed to advance the physical, chemical, and ecological recovery of these systems.

  8. The pre-LGM evolution of the Uummannaq ice Stream system in West Greenland

    NASA Astrophysics Data System (ADS)

    Roberts, David; Lane, Tim; Rea, Brice; Jamieson, Stewart

    2016-04-01

    Ice streams are a key component of an ice sheet system. They are fast flowing, dynamic corridors of ice that play a pivotal role in modulating ice flux from the interior of an ice sheet to its terrestrial or marine margin. The behaviour of marine-terminating ice streams in particular is critical in determining the dynamic (in)stability of ice sheets and ice/ocean interaction through time. However, despite an increase in palaeo-ice stream reconstructions and improvements in numerical modelling, in many instances we know little about the evolution of ice streams beyond the last glacial cycle. This is particularly true for topographically-guided or constrained ice stream systems that must represent the end-member state of a system that has developed over million year time scales. Recent research suggests that topographic focussing, subglacial geology, meltwater routing and calving margins are the primary controls on ice stream evolution. However, few studies have considered the combined role of geology, pre Quaternary landscapes and uplift in pre-conditioning a landscape for ice stream onset. This paper explores the factors that have controlled the evolution of the Uummannaq Ice Stream (UIS) system in West Greenland. During the last glacial cycle the UIS was a topographically-guided system, but the variables that led to ice stream onset prior to the Late Quaternary remain poorly understood. Geology, selective linear erosion and dynamic feedbacks were all important controls, but the influence of rifting, early uplift and pre-glacial topography in particular may have been pivotal controls on the evolution and location of the UIS onset zone.

  9. Regulatory framework for the thermal treatment of various waste streams.

    PubMed

    Lee, C C; Huffman, G L; Mao, Y L

    2000-08-28

    Since 1990, regulations and standards have changed considerably. This article is an update of the regulatory requirements for the thermal treatment of various waste streams. The waste categories covered, along with the laws they are governed under, include: Hazardous waste under Subtitle C of the Resource Conservation and Recovery Act (RCRA) and under the Clean Air Act; municipal solid waste under Subtitle D of the RCRA; medical waste under Subtitle J of the RCRA; Superfund waste under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA); toxic waste under the Toxic Substances Control Act (TSCA); and sludge waste under the Clean Water Act (CWA).

  10. Regulatory framework for the thermal treatment of various waste streams.

    PubMed

    Lee, C C; Huffman, G L; Mao, Y L

    2000-08-28

    Since 1990, regulations and standards have changed considerably. This article is an update of the regulatory requirements for the thermal treatment of various waste streams. The waste categories covered, along with the laws they are governed under, include: Hazardous waste under Subtitle C of the Resource Conservation and Recovery Act (RCRA) and under the Clean Air Act; municipal solid waste under Subtitle D of the RCRA; medical waste under Subtitle J of the RCRA; Superfund waste under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA); toxic waste under the Toxic Substances Control Act (TSCA); and sludge waste under the Clean Water Act (CWA). PMID:10863011

  11. A probe for sampling interstitial waters of stream sediments and bog soils

    USGS Publications Warehouse

    Nowlan, G.A.; Carollo, C.

    1974-01-01

    A probe for sampling interstitial waters of stream sediments and bog soils is described. Samples can be obtained within a stratigraphic interval of 2-3 cm, to a depth of 60-80 cm, and with little or no contamination of the samples by sediment or air. ?? 1974.

  12. Summary of prior grain entrapment rescue strategies.

    PubMed

    Roberts, M J; Deboy, G R; Field, W E; Maier, D E

    2011-10-01

    Entrapment in flowable agricultural material continues to be a relevant problem facing both farmers and employees of commercial grain storage and handling operations. While considerable work has been done previously on the causes of entrapment in grain and possible preventative measures, there is little research on the efficacy of current first response or extrication techniques. With the recent introduction of new grain rescue equipment and training programs, it was determined that the need exists to document and summarize prior grain rescue strategies with a view to develop evidence-based recommendations that would enhance the efficacy of the techniques used and reduce the risks to both victims and first responders. Utilizing the Purdue University Agricultural Entrapment Database, all data were queried for information related to extrication of victims from grain entrapments documented over the period 1964-2006. Also analyzed were data from other sources, including public records related to entrapments and information from onsite investigations. Significant findings of this study include the following: (1) between 1964 and 2006, the number of entrapments averaged 16 per year, with the frequency increasing over the last decade; (2) of all cases documented, about 45% resulted in fatality; (3) no less than 44% of entrapments occurred in shelled corn; (4) fatality was the result in 82% of cases where victims were submerged beneath the grain surface, while fatality occurred in 10% of cases where victims were only partially engulfed; (5) the majority of rescues were reported to have been conducted by untrained personnel who were at the scene at the time of entrapment; and (6) in those cases where the rescue strategies were known, 56% involved cutting or punching holes in the side walls of the storage structure, 19% involved utilizing onsite fabricated grain retaining walls to extricate partially entrapped victims, and the use of grain vacuum machines as a rescue

  13. Digital communication constraints in prior space missions

    NASA Technical Reports Server (NTRS)

    Yassine, Nathan K.

    2004-01-01

    Digital communication is crucial for space endeavors. Jt transmits scientific and command data between earth stations and the spacecraft crew. It facilitates communications between astronauts, and provides live coverage during all phases of the mission. Digital communications provide ground stations and spacecraft crew precise data on the spacecraft position throughout the entire mission. Lessons learned from prior space missions are valuable for our new lunar and Mars missions set by our president s speech. These data will save our agency time and money, and set course our current developing technologies. Limitations on digital communications equipment pertaining mass, volume, data rate, frequency, antenna type and size, modulation, format, and power in the passed space missions are of particular interest. This activity is in support of ongoing communication architectural studies pertaining to robotic and human lunar exploration. The design capabilities and functionalities will depend on the space and power allocated for digital communication equipment. My contribution will be gathering these data, write a report, and present it to Communications Technology Division Staff. Antenna design is very carefully studied for each mission scenario. Currently, Phased array antennas are being developed for the lunar mission. Phased array antennas use little power, and electronically steer a beam instead of DC motors. There are 615 patches in the phased array antenna. These patches have to be modified to have high yield. 50 patches were created for testing. My part is to assist in the characterization of these patch antennas, and determine whether or not certain modifications to quartz micro-strip patch radiators result in a significant yield to warrant proceeding with repairs to the prototype 19 GHz ferroelectric reflect-array antenna. This work requires learning how to calibrate an automatic network, and mounting and testing antennas in coaxial fixtures. The purpose of this

  14. Color and depth priors in natural images.

    PubMed

    Su, Che-Chun; Cormack, Lawrence K; Bovik, Alan C

    2013-06-01

    Natural scene statistics have played an increasingly important role in both our understanding of the function and evolution of the human vision system, and in the development of modern image processing applications. Because range (egocentric distance) is arguably the most important thing a visual system must compute (from an evolutionary perspective), the joint statistics between image information (color and luminance) and range information are of particular interest. It seems obvious that where there is a depth discontinuity, there must be a higher probability of a brightness or color discontinuity too. This is true, but the more interesting case is in the other direction--because image information is much more easily computed than range information, the key conditional probabilities are those of finding a range discontinuity given an image discontinuity. Here, the intuition is much weaker; the plethora of shadows and textures in the natural environment imply that many image discontinuities must exist without corresponding changes in range. In this paper, we extend previous work in two ways--we use as our starting point a very high quality data set of coregistered color and range values collected specifically for this purpose, and we evaluate the statistics of perceptually relevant chromatic information in addition to luminance, range, and binocular disparity information. The most fundamental finding is that the probabilities of finding range changes do in fact depend in a useful and systematic way on color and luminance changes; larger range changes are associated with larger image changes. Second, we are able to parametrically model the prior marginal and conditional distributions of luminance, color, range, and (computed) binocular disparity. Finally, we provide a proof of principle that this information is useful by showing that our distribution models improve the performance of a Bayesian stereo algorithm on an independent set of input images. To summarize

  15. Recent Research toward Understanding Spatial, Temporal, and Climatic Variation in Stream Temperatures across the Northwest U.S.

    NASA Astrophysics Data System (ADS)

    Isaak, D.; Roper, B.; Luce, C.; Holden, Z.

    2012-12-01

    Global air temperature increases raise concerns about effects on thermal regimes of the Earth's rivers and streams. These concerns are acute in the Northwest U.S. due to legislatively mandated water quality standards and the importance of recreational and commercial fisheries for cold-water species such as salmon and trout. Efforts to study climate effects on stream thermal regimes are limited by sparse long-term monitoring records, resulting in a lack of information on historical spatial and temporal variation from which to measure departure. We present research from the last five years that begins to address these shortcomings, including: 1) estimation of stream warming rates in recent decades associated with long-term climate change (+0.11 °C/decade for mean annual temperatures; +0.22 °C/decade for summer temperatures), 2) development of an inexpensive protocol for monitoring full-year temperatures in dynamic mountain streams, 3) rapid expansion of an informal regional monitoring network from < 1,000 stream sites to > 3,000 sites in the last three years, 4) development and use of high-resolution (i.e., 100's of meters) air temperature microclimate models to understand variation in stream temperatures, 5) development of NorWeST, a comprehensive stream temperature database consisting of > 45,000 summers of temperature measurement at > 15,000 unique stream sites, and 6) use of new spatial statistical stream network models with NorWeST to krige predictions at unsampled locations and develop thermal information for most of the region's 350,000 stream kilometers. There is much yet to be learned regarding thermal regimes in rivers and streams but the accelerating pace of knowledge discovery driven by inexpensive sensors, computational improvements, geospatial technologies, and new analyses suggests that many important remaining unknowns will be resolved in the next five years.

  16. Crevasse-squeeze ridge corridors: Diagnostic features of late-stage palaeo-ice stream activity

    NASA Astrophysics Data System (ADS)

    Evans, David J. A.; Storrar, Robert D.; Rea, Brice R.

    2016-04-01

    A 200-km-long and 10-km-wide linear assemblage of till-filled geometrical ridges on the bed of the Maskwa palaeo-ice stream of the late Wisconsinan southwest Laurentide Ice Sheet are interpreted as crevasse-squeeze ridges (CSR) developed during internal flow unit reorganization, immediately prior to ice stream shutdown. Ridge orientations are predominantly orientated WNW-ESE, with a subordinate WSW-ENE alignment, both indicative of ice fracture development transverse to former ice stream flow, as indicated by NNE-SSW aligned MSGL. Subglacial till injection into basal and/or full depth, mode I and II crevasses occurred at the approximate centreline of the ice stream, in response to extension and fracturing. Landform preservation indicates that this took place during the final stages of ice streaming, immediately prior to ice stream shutdown. This linear zone of ice fracturing therefore likely represents the narrowing of the fast-flowing trunk, similar to the plug flow identified in some surging valley glaciers. Lateral drag between the final active flow unit and the slower moving ice on either side is likely recorded by the up-ice bending of the CSR limbs. The resulting CSR corridor, here related to an individual ice stream flow unit, constitutes a previously unreported style of crevasse infilling and contrasts with two existing CSR patterns: (1) wide arcuate zones of CSRs related to widespread fracturing within glacier surge lobes; and (2) narrow concentric arcs of CSRs and recessional push moraines related to submarginal till deformation at active temperate glacier lobes.

  17. DEMONSTRATION BULLETIN: ADSORPTION-INTEGRATED-REACTION (AIR2000) PROCESS, KSE, INC.

    EPA Science Inventory

    This Bulletin is a brief description of the AIR2000 technology developed by KSE, Inc., of Amherst, MA. The AIR2000 unit treats air streams containing volatile organic compounds (VOCs). The demonstration occurred at the Stamina Mills superfund site in North Smithfield, RI from Aug...

  18. Utilizing Prior Information for Depth to Improve Seismic Event Discrimination

    NASA Astrophysics Data System (ADS)

    Carlson, D. K.; Kane, K.; Anderson, D. N.; Schult, F. R.; Ballard, S.

    2006-05-01

    We are developing and testing a novel location algorithm for estimating the depth of a seismic event in order to improve the discrimination of events. Information from the algorithm will be incorporated into a statistically based discrimination framework to determine the source of an event. The depth estimation approach differs from currently used algorithms, which use non-linear regression techniques, by using Bayesian techniques to incorporate prior information about the depth of an event. We use first arriving P-waves and their associated modeled travel times to estimate the most likely event depth. The likelihood is constructed with gaussian errors. Depth may be modeled as a skewed distribution if characteristics of the waveforms from an event indicate that bounds on the depth are appropriate. For instance, the Rg phase is present in a wave form only when an event is shallow. Therefore, the presence of Rg in a dataset could lead one to assume a shallow- skewed prior distribution for the depth parameter. For most seismic event data sets, depth and origin time are the hypocentral parameters that are most poorly constrained because of the source-receiver geometry imposed by the Earth. It is not unusual for current location algorithms to return event solutions that fit the data very well and yet have event depths that are above the surface of the earth (so called "air quakes") or well below the known limits of seismicity for a given area. The solutions are statistically valid in that the confidence bounds are large enough to encompass more realistic depths the specified percent of the time, but they are unsatisfying to seismologists. The effect of repeatedly seeing such unreasonable depths is to develop a mistrust of the depth determinations in all cases, even when depth may be well constrained. What is needed is a means to flexibly incorporate apriori information about acceptable depth distributions to better constrain the hypocentral depth estimates when they are

  19. The Influence of Prior Knowledge on the Retrieval-Directed Function of Note Taking in Prior Knowledge Activation

    ERIC Educational Resources Information Center

    Wetzels, Sandra A. J.; Kester, Liesbeth; van Merrienboer, Jeroen J. G.; Broers, Nick J.

    2011-01-01

    Background: Prior knowledge activation facilitates learning. Note taking during prior knowledge activation (i.e., note taking directed at retrieving information from memory) might facilitate the activation process by enabling learners to build an external representation of their prior knowledge. However, taking notes might be less effective in…

  20. Improved compressed sensing-based cone-beam CT reconstruction using adaptive prior image constraints

    NASA Astrophysics Data System (ADS)

    Lee, Ho; Xing, Lei; Davidi, Ran; Li, Ruijiang; Qian, Jianguo; Lee, Rena

    2012-04-01

    Volumetric cone-beam CT (CBCT) images are acquired repeatedly during a course of radiation therapy and a natural question to ask is whether CBCT images obtained earlier in the process can be utilized as prior knowledge to reduce patient imaging dose in subsequent scans. The purpose of this work is to develop an adaptive prior image constrained compressed sensing (APICCS) method to solve this problem. Reconstructed images using full projections are taken on the first day of radiation therapy treatment and are used as prior images. The subsequent scans are acquired using a protocol of sparse projections. In the proposed APICCS algorithm, the prior images are utilized as an initial guess and are incorporated into the objective function in the compressed sensing (CS)-based iterative reconstruction process. Furthermore, the prior information is employed to detect any possible mismatched regions between the prior and current images for improved reconstruction. For this purpose, the prior images and the reconstructed images are classified into three anatomical regions: air, soft tissue and bone. Mismatched regions are identified by local differences of the corresponding groups in the two classified sets of images. A distance transformation is then introduced to convert the information into an adaptive voxel-dependent relaxation map. In constructing the relaxation map, the matched regions (unchanged anatomy) between the prior and current images are assigned with smaller weight values, which are translated into less influence on the CS iterative reconstruction process. On the other hand, the mismatched regions (changed anatomy) are associated with larger values and the regions are updated more by the new projection data, thus avoiding any possible adverse effects of prior images. The APICCS approach was systematically assessed by using patient data acquired under standard and low-dose protocols for qualitative and quantitative comparisons. The APICCS method provides an

  1. Marginally specified priors for non-parametric Bayesian estimation

    PubMed Central

    Kessler, David C.; Hoff, Peter D.; Dunson, David B.

    2014-01-01

    Summary Prior specification for non-parametric Bayesian inference involves the difficult task of quantifying prior knowledge about a parameter of high, often infinite, dimension. A statistician is unlikely to have informed opinions about all aspects of such a parameter but will have real information about functionals of the parameter, such as the population mean or variance. The paper proposes a new framework for non-parametric Bayes inference in which the prior distribution for a possibly infinite dimensional parameter is decomposed into two parts: an informative prior on a finite set of functionals, and a non-parametric conditional prior for the parameter given the functionals. Such priors can be easily constructed from standard non-parametric prior distributions in common use and inherit the large support of the standard priors on which they are based. Additionally, posterior approximations under these informative priors can generally be made via minor adjustments to existing Markov chain approximation algorithms for standard non-parametric prior distributions. We illustrate the use of such priors in the context of multivariate density estimation using Dirichlet process mixture models, and in the modelling of high dimensional sparse contingency tables. PMID:25663813

  2. Measure Guideline: Guide to Attic Air Sealing

    SciTech Connect

    Lstiburek, Joseph

    2014-09-01

    The purpose of this measure guideline is to provide information and recommendations for the preparation work necessary prior to adding attic insulation. Even though the purpose of this guide is to save energy, health, safety, and durability should not be compromised by energy efficiency. Accordingly, combustion safety and ventilation for indoor air quality are addressed first. Durability and attic ventilation then follow. Finally, to maximize energy savings, air sealing is completed prior to insulating. The guide is intended for home remodelers, builders, insulation contractors, mechanical contractors, general contractors who have previously done remodeling and homeowners as a guide to the work that needs to be done.

  3. The atmosphere can be a source of certain water soluble volatile organic compounds in urban streams

    USGS Publications Warehouse

    Kenner, Scott J.; Bender, David A.; Zogorski, John S.; ,; James F. Pankow,

    2014-01-01

    Surface water and air volatile organic compound (VOC) data from 10 U.S. Geological Survey monitoring sites were used to evaluate the potential for direct transport of VOCs from the atmosphere to urban streams. Analytical results of 87 VOC compounds were screened by evaluating the occurrence and detection levels in both water and air, and equilibrium concentrations in water (Cws) based on the measured air concentrations. Four compounds (acetone, methyl tertiary butyl ether, toluene, and m- & p-xylene) were detected in more than 20% of water samples, in more than 10% of air samples, and more than 10% of detections in air were greater than long-term method detection levels (LTMDL) in water. Benzene was detected in more than 20% of water samples and in more than 10% of air samples. Two percent of benzene detections in air were greater than one-half the LTMDL in water. Six compounds (chloroform, p-isopropyltoluene, methylene chloride, perchloroethene, 1,1,1-trichloroethane, and trichloroethene) were detected in more than 20% of water samples and in more than 10% of air samples. Five VOCs, toluene, m- & p-xylene, methyl tert-butyl ether (MTBE), acetone, and benzene were identified as having sufficiently high concentrations in the atmosphere to be a source to urban streams. MTBE, acetone, and benzene exhibited behavior that was consistent with equilibrium concentrations in the atmosphere.

  4. Stream Temperature Variability as an Indicator of Groundwater-Surface Water Interactions in Two Groundwater-Fed Streams

    NASA Astrophysics Data System (ADS)

    Middleton, M.; Allen, D. M.

    2009-12-01

    , consistent with a greater groundwater input. In contrast, Bertrand Creek water temperature patterns resembled the variability in the air temperatures, which ranged from -7.7oC to 32.4oC, with daily and seasonal fluctuations. The different responses in the stream suggest that stream morphology, riparian cover and/or surficial geology/land use are influencing timing and magnitude of the groundwater-surface water interactions. Fishtrap Creek has limited riparian cover and is situated in heterogeneous coarse grained surficial deposits. In contrast, Bertrand Creek has well developed riparian cover and is situated in a fine grained, low conductivity surficial geology unit. Despite the lack of riparian cover, which generally buffers water temperatures, Fishtrap Creek was found to have a generally stable water temperature regime relative to Bertrand Creek. The results suggest that the surficial geology of each stream exerts a greater influence on the groundwater-surface water interactions than do the riparian cover and land use patterns.

  5. Preparation of sorbent pellets with high integrity for sorption of CO.sub.2 from gas streams

    DOEpatents

    Siriwardane, Ranjani V.

    2016-05-10

    Method for the production of a CO.sub.2 sorbent prepared by integrating a clay substrate, basic alkali salt, amine liquid, hydraulic binder, and a liquid binder. The basic alkali salt is present relative to the clay substrate in a weight ratio of from about 1 part to about 50 parts per 100 parts of the clay substrate. The amine liquid is present relative to a clay-alkali combination in a weight ratio of from about 1 part to about 10 parts per 10 parts of the clay-alkali combination. The clay substrate and basic alkali salt may be combined in a solid-solid heterogeneous mixture and followed by introduction of the amine liquid. Alternatively, an alkaline solution may be blended with the amine solution prior to contacting the clay substrate. The clay-alkali-amine CO.sub.2 sorbent is particularly advantageous for low temperature CO.sub.2 removal cycles in a gas stream having a CO.sub.2 concentration less than around 2000 ppm and an oxygen concentration around 21%, such as air.

  6. Stream diurnal dissolved oxygen profiles as indicators of in-stream metabolism and disturbance effects: Fort Benning as a case study

    SciTech Connect

    Mulholland, Patrick J

    2005-01-01

    We investigated whether two characteristics of stream diurnal dissolved oxygen profiles, the daily amplitude and maximum value of the dissolved oxygen saturation deficit, are useful indicators of stream metabolism and the effects of catchment-scale disturbances. The study was conducted at the U.S. Army's Fort Benning installation where vegetation loss and high rates of erosion from intensely used training areas and unpaved roads have resulted in extensive sedimentation in some streams. Diurnal profiles of dissolved oxygen were measured in 10 second-order streams draining catchments which exhibited a range of disturbance levels. Rates of gross primary production (GPP) and total ecosystem respiration (R) per unit surface area were determined for each stream using the single-station diurnal dissolved oxygen change method with direct measurement of air-water oxygen exchange rates. The daily amplitude of the diurnal dissolved oxygen deficit profile was highly correlated with daily rates of GPP, and multiplying the daily amplitude by average stream depth to account for differences in water volume did not improve the correlation. The daily maximum dissolved oxygen deficit was highly correlated with daily rates of R, and multiplying by average stream depth improved the correlation. In general, these indicators of stream metabolism declined sharply with increasing catchment disturbance level, although the indicators of R showed a more consistent relationship with disturbance level than those of GPP. Our results show that the daily amplitude and maximum value of diurnal dissolved oxygen deficit profiles are good indicators of reach-scale rates of metabolism and the effects of catchment-scale disturbance on these metabolism rates. At Fort Benning, and presumably at other military installations, they are useful tools for evaluating trends in impacts from military training or rates of recovery following restoration activities.

  7. Air surveillance

    SciTech Connect

    Patton, G.W.

    1995-06-01

    This section of the 1994 Hanford Site Environmental Report summarizes the air surveillance and monitoring programs currently in operation at that Hanford Site. Atmospheric releases of pollutants from Hanford to the surrounding region are a potential source of human exposure. For that reason, both radioactive and nonradioactive materials in air are monitored at a number of locations. The influence of Hanford emissions on local radionuclide concentrations was evaluated by comparing concentrations measured at distant locations within the region to concentrations measured at the Site perimeter. This section discusses sample collection, analytical methods, and the results of the Hanford air surveillance program. A complete listing of all analytical results summarized in this section is reported separately by Bisping (1995).

  8. Streams in Catskill Mountains still susceptible to acid rain

    NASA Astrophysics Data System (ADS)

    Burns, Douglas A.; Lawrence, Gregory B.; Murdoch, Peter S.

    Precipitation in North America has become less acidic over the past 2 decades because of reduced power plant emissions and compliance with the Clean Air Act Amendments [Sirois, 19937rsqb;. The 1990 Clean Air Act Amendments were developed to reduce the acidity of sensitive surface waters, which are primarily in upland forested environments, where acidified waters and associated high aluminum concentrations are toxic to many species of aquatic flora and fauna [Schindler et al., 1989]. Our studies show that in spite of less acidic precipitation, the buffering capacity of streams in upland forests of the Catskill Mountains in southeastern New York has not increased in recent years. These data suggest that long-term leaching by acid rain has lowered exchangeable calcium ion concentrations in the soil in upland areas, where the underlying, slow-weathering bedrock provides an inadequate supply of cations to neutralize acidity.

  9. Development of Metrics to Assess Effectiveness of Stream Restoration in Second-Growth Forests

    NASA Astrophysics Data System (ADS)

    Stockwell, E.; Johnson, A. C.; Edwards, R.

    2010-12-01

    This project was designed to develop and test metrics to assess whether stream restoration work in second growth riparian areas produces measurable changes in ecosystem function. Proposed metrics evaluate anadramadous fish and the trophic basis for their production. These metrics consist of: measuring benthic chlorophyll a and photosynthetically active radiation (PAR) to detect changes in primary production, computing invertebrate litterfall as allochthonous food inputs into the streams, evaluating transient storage, counting the number and depth of pools, counting the number of pieces of large wood, and determining the substrate size of the stream to detect changes in channel retentiveness and habitat availability. Data were collected prior to restoration treatment. Restoration work is expected to increase growth and survival of anadramous fish by increasing availability of high quality habitat and food. Although there is large variation in the data collected, preliminary results show a positive correlation between the number of invertebrates, especially of the subclass collembola, collected in the litterfall and the percent of PAR reaching the stream. There is also a correlation between an increase in the percent of PAR reaching the stream and an increase in the amount of alder in the riparian area. This suggests that riparian areas with a majority of alder trees could provide more invertebrate food for fish in the streams.

  10. A multi-scaled approach to evaluating the fish assemblage structure within southern Appalachian streams USA.

    USGS Publications Warehouse

    Kirsch, Joseph; Peterson, James T.

    2014-01-01

    There is considerable uncertainty about the relative roles of stream habitat and landscape characteristics in structuring stream-fish assemblages. We evaluated the relative importance of environmental characteristics on fish occupancy at the local and landscape scales within the upper Little Tennessee River basin of Georgia and North Carolina. Fishes were sampled using a quadrat sample design at 525 channel units within 48 study reaches during two consecutive years. We evaluated species–habitat relationships (local and landscape factors) by developing hierarchical, multispecies occupancy models. Modeling results suggested that fish occupancy within the Little Tennessee River basin was primarily influenced by stream topology and topography, urban land coverage, and channel unit types. Landscape scale factors (e.g., urban land coverage and elevation) largely controlled the fish assemblage structure at a stream-reach level, and local-scale factors (i.e., channel unit types) influenced fish distribution within stream reaches. Our study demonstrates the utility of a multi-scaled approach and the need to account for hierarchy and the interscale interactions of factors influencing assemblage structure prior to monitoring fish assemblages, developing biological management plans, or allocating management resources throughout a stream system.

  11. Simulation Data as Data Streams

    SciTech Connect

    Abdulla, G; Arrighi, W; Critchlow, T

    2003-11-18

    Computational or scientific simulations are increasingly being applied to solve a variety of scientific problems. Domains such as astrophysics, engineering, chemistry, biology, and environmental studies are benefiting from this important capability. Simulations, however, produce enormous amounts of data that need to be analyzed and understood. In this overview paper, we describe scientific simulation data, its characteristics, and the way scientists generate and use the data. We then compare and contrast simulation data to data streams. Finally, we describe our approach to analyzing simulation data, present the AQSim (Ad-hoc Queries for Simulation data) system, and discuss some of the challenges that result from handling this kind of data.

  12. Air/Superfund national technical guidance study series: Estimation of air impacts for air stripping of contaminated water

    SciTech Connect

    Eklund, B.; Smith, S.; Hunt, M.

    1991-05-01

    Analysis of the air impacts associated with the alternatives to cleaning up Superfund sites is frequently required for planning purposes prior to actual cleanup. Such analyses depend on estimates rather than on field measurements. The report provides procedures for estimating the emissions and ambient air concentrations associated with air stripping - a widely used technique for removing volatile organic compounds (VOC) from contaminated water. Procedures are given to evaluate the effect of the concentration of contaminants in water, the stripping efficiency and the stripping rate on the emission rates and on the ambient air concentrations at selected distances from the air stripper. Henry's Law constants are provided for over 130 compounds to assist in determining stripping efficiencies. Health-based action levels are also provided for the 130 compounds for comparison to the estimated ambient air concentrations. Action levels are also expressed in terms of water concentrations using conservative estimates of emissions and dispersion.

  13. Software to Control and Monitor Gas Streams

    NASA Technical Reports Server (NTRS)

    Arkin, C.; Curley, Charles; Gore, Eric; Floyd, David; Lucas, Damion

    2012-01-01

    This software package interfaces with various gas stream devices such as pressure transducers, flow meters, flow controllers, valves, and analyzers such as a mass spectrometer. The software provides excellent user interfacing with various windows that provide time-domain graphs, valve state buttons, priority- colored messages, and warning icons. The user can configure the software to save as much or as little data as needed to a comma-delimited file. The software also includes an intuitive scripting language for automated processing. The configuration allows for the assignment of measured values or calibration so that raw signals can be viewed as usable pressures, flows, or concentrations in real time. The software is based on those used in two safety systems for shuttle processing and one volcanic gas analysis system. Mass analyzers typically have very unique applications and vary from job to job. As such, software available on the market is usually inadequate or targeted on a specific application (such as EPA methods). The goal was to develop powerful software that could be used with prototype systems. The key problem was to generalize the software to be easily and quickly reconfigurable. At Kennedy Space Center (KSC), the prior art consists of two primary methods. The first method was to utilize Lab- VIEW and a commercial data acquisition system. This method required rewriting code for each different application and only provided raw data. To obtain data in engineering units, manual calculations were required. The second method was to utilize one of the embedded computer systems developed for another system. This second method had the benefit of providing data in engineering units, but was limited in the number of control parameters.

  14. Transport, behavior, and fate of volatile organic compounds in streams

    USGS Publications Warehouse

    Rathbun, R.E.

    2000-01-01

    Volatile organic compounds (VOCs) are compounds with chemical and physical properties that allow the compounds to move freely between the water and air phases of the environment. VOCs are widespread in the environment because of this mobility. Many VOCs have properties that make them suspected or known hazards to the health of humans and aquatic organisms. Consequently, understanding the processes affecting the concentration and distribution of VOCs in the environment is necessary. The transport, behavior, and fate of VOCs in streams are determined by combinations of chemical, physical, and biological processes. These processes are volatilization, absorption, wet and dry deposition, microbial degradation, sorption, hydrolysis, aquatic photolysis, oxidation, chemical reaction, biocon-centration, advection, and dispersion. The relative importance of each of these processes depends on the characteristics of the VOC and the stream. The U.S. Geological Survey National Water-Quality Assessment Program selected 55 VOCs for study. This article reviews the characteristics of the various processes that could affect the transport, behavior, and fate of these VOCs in streams.

  15. Cortisol and Pacific Salmon: A New Look at the Role of Stress Hormones in Olfaction and Home-stream Migration.

    PubMed

    Carruth, Laura L; Jones, Richard E; Norris, David O

    2002-07-01

    Pacific salmon (genus Oncorhynchus) exhibit an interesting and uncommon life-history pattern that combines semelparity, anadromy, and navigation (homing). During smoltification, young salmon imprint on the chemical composition of their natal stream water (the home-stream olfactory bouquet or "HSOB"); they then migrate to the ocean where they spend a few years feeding prior to migrating back to their natal freshwater stream to spawn. Upstream migration is guided by the amazing ability to discriminate between the chemical compositions of different stream waters and thus identify and travel to their home-stream. Pacific salmon demonstrate marked somatic and neural degeneration changes during home-stream migration and at the spawning grounds. The appearance of these pathologies is correlated with a marked elevation in plasma cortisol levels. While the mechanisms of salmonid homing are not completely understood, it is known that adult salmon continuously utilize two of their primary sensory systems, olfaction and vision, during homing. Olfaction is the primary sensory system involved in freshwater homing and "HSOB" recognition, and will be emphasized here. Previously, we proposed that the increase in plasma cortisol during Pacific salmon home-stream migration is adaptive because it enhances the salmon's ability to recall the imprinted memory of the "HSOB" (Carruth, 1998; Carruth et al., 2000b). Elevated plasma concentrations of cortisol could prime the hippocampus or other olfactory regions of the brain to recall this memory and, therefore, aid in directing the fish to their natal stream. Thus, specific responses of salmon to stressors could enhance reproductive success.

  16. Trends and Controls on Summer Surface-Water Temperatures in Salmonid-Bearing Headwater Streams in Two Common Geomorphic Settings, Kenai Peninsula, Alaska

    NASA Astrophysics Data System (ADS)

    Callahan, M. K.; Bellino, J. C.; Rains, M. C.

    2010-12-01

    Stream temperature is an important physical characteristic of headwater streams that plays a critical role in the presence and health of juvenile salmonids. Headwater stream temperature was documented in two geomorphic settings on the Kenai Peninsula, Alaska, focusing on the variation in temperature induced by diffuse groundwater discharge and variable air temperature. Eighteen headwater stream reaches were studied in four watersheds, with 11 drainageway sites and seven discharge-slope sites. In drainageway sites, low-gradient streams flow through broad valleys with groundwater-fed fen wetlands; in discharge-slope sites, high-gradient streams flow through narrow valleys with groundwater-fed slope wetlands. At all 18 sites, hourly stream temperatures were measured for one year. At one drainageway and one discharge-slope site, groundwater temperatures, stream stages, and groundwater heads in the local groundwater flow systems were also measured hourly for a year. A process-based, mechanistic surface-water temperature model (SSTEMP) was used to identify the importance of surface-water temperature controls, particularly the role of groundwater discharge and air temperature, at the two highly instrumented sites. The contribution of groundwater to flow was calculated using a mass-balance water quality mixing model. Groundwater discharge represented 40-60 percent of total stream flow in both geomorphic settings. However, stream and groundwater temperature characteristics differed between the two geomorphic settings. Stream and groundwater temperatures were tightly coupled in the discharge-slope site but not in the drainageway site. Furthermore, warmer stream temperatures occurred at the drainageway site compared to the discharge-slope site, especially during the late summer. SSTEMP simulations indicate that diffuse groundwater discharge does not greatly affect changes in stream temperature at either geomorphic setting, corroborating field observations that focused

  17. Persistence probabilities for stream populations.

    PubMed

    Samia, Yasmine; Lutscher, Frithjof

    2012-07-01

    Individuals in streams and rivers are constantly at risk of being washed downstream and thereby lost to their population. The possibility of diffusion-mediated persistence of populations in advective environments has been the focus of a multitude of recent modeling efforts. Most of these recent models are deterministic, and they predict the existence of a critical advection velocity, above which a population cannot persist. In this work, we present a stochastic approach to the persistence problem in streams and rivers. We use the dominant eigenvalue of the advection-diffusion operator to transition from a spatially explicit description to a spatially implicit birth-death process, in which individual washout from the domain appears as an additional death term. We find that the deterministic persistence threshold is replaced by a smooth transition from almost sure persistence to extinction as advection velocity increases. More interestingly, we explore how temporal variation in flow rate and other parameters affect the persistence probability. In line with general expectations, we find that temporal variation often decreases the persistence probability, and we focus on a few examples of how variation can increase population persistence.

  18. Streaming potential measurements of biosurfaces

    NASA Technical Reports Server (NTRS)

    Van Wagenen, R. A.; Andrade, J. D.; Hibbs, J. B., Jr.

    1976-01-01

    A technique based on the measurement of streaming potentials has been developed to evaluate the electrokinetic region of the cell periphery. This approach is feasible for cell lines propagated in in-vitro cell cultures in monolayer form. The advantage of this system is that cells may be evaluated in the living state atttached to a substrate; it is not necessary to subject the cells to enzymatic, chemical, or mechanical trauma required to obtain monodisperse suspensions which are then normally evaluated by microelectrophoresis. In this manner, it should be possible to study the influence of substrate and environmental factors on the charge density and potential at the cell periphery. The apparatus and procedure are described as well as some results concerning the electrokinetic potential of borosilicate capillaries as a function of ionic strength, pH, and temperature. The effect that turbulence and entrance flow conditions have on accurate streaming-potential measurements is discussed. The electrokinetic potential of BALB/c 3T12 fibroblasts has been quantified as a function of pH, ionic strength, glutaraldehyde fixation, and Giemsa staining.

  19. Downstream Warming and Headwater Acidity May Diminish Coldwater Habitat in Southern Appalachian Mountain Streams.

    PubMed

    McDonnell, T C; Sloat, M R; Sullivan, T J; Dolloff, C A; Hessburg, P F; Povak, N A; Jackson, W A; Sams, C

    2015-01-01

    Stream-dwelling species in the U.S. southern Appalachian Mountains region are particularly vulnerable to climate change and acidification. The objectives of this study were to quantify the spatial extent of contemporary suitable habitat for acid- and thermally sensitive aquatic species and to forecast future habitat loss resulting from expected temperature increases on national forest lands in the southern Appalachian Mountain region. The goal of this study was to help watershed managers identify and assess stream reaches that are potentially vulnerable to warming, acidification, or both. To our knowledge, these results represent the first regional assessment of aquatic habitat suitability with respect to the combined effects of stream water temperature and acid-base status in the United States. Statistical models were developed to predict July mean daily maximum water temperatures and air-water temperature relations to determine potential changes in future stream water temperatures. The length of stream considered suitable habitat for acid- and thermally sensitive species, based on temperature and acid neutralizing capacity thresholds of 20°C and 50 μeq/L, was variable throughout the national forests considered. Stream length displaying temperature above 20°C was generally more than five times greater than the length predicted to have acid neutralizing capacity below 50 μeq/L. It was uncommon for these two stressors to occur within the same stream segment. Results suggested that species' distributional shifts to colder, higher elevation habitats under a warming climate can be constrained by acidification of headwater streams. The approach used in this study can be applied to evaluate climate change impacts to stream water resources in other regions. PMID:26247361

  20. Downstream Warming and Headwater Acidity May Diminish Coldwater Habitat in Southern Appalachian Mountain Streams.

    PubMed

    McDonnell, T C; Sloat, M R; Sullivan, T J; Dolloff, C A; Hessburg, P F; Povak, N A; Jackson, W A; Sams, C

    2015-01-01

    Stream-dwelling species in the U.S. southern Appalachian Mountains region are particularly vulnerable to climate change and acidification. The objectives of this study were to quantify the spatial extent of contemporary suitable habitat for acid- and thermally sensitive aquatic species and to forecast future habitat loss resulting from expected temperature increases on national forest lands in the southern Appalachian Mountain region. The goal of this study was to help watershed managers identify and assess stream reaches that are potentially vulnerable to warming, acidification, or both. To our knowledge, these results represent the first regional assessment of aquatic habitat suitability with respect to the combined effects of stream water temperature and acid-base status in the United States. Statistical models were developed to predict July mean daily maximum water temperatures and air-water temperature relations to determine potential changes in future stream water temperatures. The length of stream considered suitable habitat for acid- and thermally sensitive species, based on temperature and acid neutralizing capacity thresholds of 20°C and 50 μeq/L, was variable throughout the national forests considered. Stream length displaying temperature above 20°C was generally more than five times greater than the length predicted to have acid neutralizing capacity below 50 μeq/L. It was uncommon for these two stressors to occur within the same stream segment. Results suggested that species' distributional shifts to colder, higher elevation habitats under a warming climate can be constrained by acidification of headwater streams. The approach used in this study can be applied to evaluate climate change impacts to stream water resources in other regions.

  1. Downstream Warming and Headwater Acidity May Diminish Coldwater Habitat in Southern Appalachian Mountain Streams

    PubMed Central

    Jackson, W. A; Sams, C.

    2015-01-01

    Stream-dwelling species in the U.S. southern Appalachian Mountains region are particularly vulnerable to climate change and acidification. The objectives of this study were to quantify the spatial extent of contemporary suitable habitat for acid- and thermally sensitive aquatic species and to forecast future habitat loss resulting from expected temperature increases on national forest lands in the southern Appalachian Mountain region. The goal of this study was to help watershed managers identify and assess stream reaches that are potentially vulnerable to warming, acidification, or both. To our knowledge, these results represent the first regional assessment of aquatic habitat suitability with respect to the combined effects of stream water temperature and acid-base status in the United States. Statistical models were developed to predict July mean daily maximum water temperatures and air-water temperature relations to determine potential changes in future stream water temperatures. The length of stream considered suitable habitat for acid- and thermally sensitive species, based on temperature and acid neutralizing capacity thresholds of 20°C and 50 μeq/L, was variable throughout the national forests considered. Stream length displaying temperature above 20°C was generally more than five times greater than the length predicted to have acid neutralizing capacity below 50 μeq/L. It was uncommon for these two stressors to occur within the same stream segment. Results suggested that species’ distributional shifts to colder, higher elevation habitats under a warming climate can be constrained by acidification of headwater streams. The approach used in this study can be applied to evaluate climate change impacts to stream water resources in other regions. PMID:26247361

  2. Impacts of Permafrost Degradation on Stream Geomorphology and Sediment Transport in Taylor Valley, Antarctica

    NASA Astrophysics Data System (ADS)

    Gooseff, M. N.; Sudman, Z. W.

    2015-12-01

    The McMurdo Dry Valleys (MDV) of Antarctica are a unique ice-free landscape that supports complex, microbially dominated ecosystems despite the harsh environment (<10 cm water equivalent/yr, -18°C mean air temperature). Recent observations suggest that this region is nearing a threshold of rapid landscape change. One such observation was the recent discovery of extensive thermokarst development (permafrost thaw features) along the banks of Crescent Stream in Taylor Valley. In 2012, a large stretch of the West Branch of Crescent Stream had significant bank failures, while the adjacent East Branch was unaffected. The objective of this study was to determine the rate of land surface change occurring on the stream bank, and the impacts of the sediment loading on the stream bed material. Three annually repeated terrestrial LiDAR scans were compared to determine the rates of ground surface change due to thermokarst degradation on the stream bank. The areal extent of the thermokarst was shown to be decreasing, however the average vertical erosion rate remained constant. Field measurements including, pebble counts, fine sediment counts, and sieve samples were collected and analyzed to determine the effects of the introduction of fine sediment on the stream bed material. The bed sediment of the thermokarst-impacted branch was consistently finer than the adjacent unaffected branch. The fine material introduced to the stream altered the bed material composition, which consequently increased the mobility of the of the bed material. These changes imposed on the stream have implications for stream morphology, endemic algal mat communities, and downstream aquatic systems.

  3. Air Pollution.

    ERIC Educational Resources Information Center

    Scorer, Richard S.

    The purpose of this book is to describe the basic mechanisms whereby pollution is transported and diffused in the atmosphere. It is designed to give practitioners an understanding of basic mechanics and physics so they may have a correct basis on which to formulate their decisions related to practical air pollution control problems. Since many…

  4. Air Pollution

    PubMed Central

    Clifton, Marjorie

    1964-01-01

    Dr Marjorie Clifton describes the classification of gaseous and nongaseous constituents of air pollution and then outlines the methods of measuring these. The National Survey embraced 150 towns of all sizes throughout England and Wales and provided data on smoke and sulphur dioxide in relation to climate, topography, industrialization, population density, fuel utilization and urban development. Dr W C Turner discusses the relationship between air pollution and mortality from respiratory conditions, and particularly the incidence of chronic bronchitis. He postulates a theory that such respiratory conditions arise as an allergy to the spores of certain moulds, spore formation being encouraged by the air humidity in Greatv Britain and overcrowded and damp living conditions. He describes the results of a twenty-week study undertaken in 1962-3, showing associations between respiratory disease and levels of air pollution. Dr Stuart Carne undertook a survey in general practice to plot the patterns of respiratory illness in London during the winter of 1962-3. There were two peaks of respiratory illnesses coinciding with the fog at the beginning of December and the freeze-up from the end of December until the beginning of March. PMID:14178955

  5. NUTRIENT DYNAMICS IN STREAMS AND THE ROLE OF J-NABS

    SciTech Connect

    Mulholland, Patrick J; Webster, Jackson

    2010-01-01

    Nutrient dynamics in streams has been an important topic of research since the 1960s. Here we review this topic and the significant role played by J-NABS in its development. We limit this review almost exclusively to studies of N and P because these elements have been shown to limit productivity in streams. We use the expression nutrient dynamics for studies that included some measures of biological processes occurring within streams. Prior to the 1970s, instream biological processes were little studied, but through 1985 conceptual advances were made, and 4 types of studies made important contributions to our understanding of instream processes: (1) evidence of increased plant production and decomposition in response to nutrient addition, (2) studies showing a downstream decrease in nutrient concentrations, (3) studies using radioisotopes, and (4) budget studies. Beginning with the first paper printed in its first issue, J-NABS has been the outlet for key papers advancing our understanding of rates and controls of nutrient dynamics in streams. In the first few years, an important review and a conceptual model for conducting experiments to study nutrient dynamics in streams were published in J-NABS. In the 1990s, J-NABS published a number of papers on nutrient recycling within algal communities, the role of the hyporheic zone, the role of spawning fish, and the coupling of data from field {sup 15}N additions and a N-cycling model to provide a synoptic view of N dynamics in streams. Since 2000, J-NABS has published influential studies on nutrient criteria for streams, rates of and controls on nitrification and denitrification, uptake of stream nutrients by riparian vegetation, and nutrient dynamics in urban streams. Nutrient dynamics will certainly continue to be an important topic in J-NABS. Topics needing further study include techniques for studying nutrient dynamics, nutrient dynamics in larger streams and rivers, the ultimate fate of nutrients taken up by plants

  6. GCN: a gaseous Galactic halo stream?

    NASA Astrophysics Data System (ADS)

    Jin, Shoko

    2010-10-01

    We show that a string of HI clouds that form part of the high-velocity cloud complex known as GCN is a probable gaseous stream extending over more than 50° in the Galactic halo. The radial velocity gradient along the stream is used to deduce transverse velocities as a function of distance, enabling a family of orbits to be computed. We find that a direction of motion towards the Galactic disc coupled with a mid-stream distance of ~20kpc provides a good match to the observed sky positions and radial velocities of the HI clouds comprising the stream. With an estimated mass of 105Msolar, its progenitor is likely to be a dwarf galaxy. However, no stellar counterpart has been found amongst the currently known Galactic dwarf spheroidal galaxies or stellar streams and the exact origin of the stream is therefore currently unknown.

  7. Sentiment Knowledge Discovery in Twitter Streaming Data

    NASA Astrophysics Data System (ADS)

    Bifet, Albert; Frank, Eibe

    Micro-blogs are a challenging new source of information for data mining techniques. Twitter is a micro-blogging service built to discover what is happening at any moment in time, anywhere in the world. Twitter messages are short, and generated constantly, and well suited for knowledge discovery using data stream mining. We briefly discuss the challenges that Twitter data streams pose, focusing on classification problems, and then consider these streams for opinion mining and sentiment analysis. To deal with streaming unbalanced classes, we propose a sliding window Kappa statistic for evaluation in time-changing data streams. Using this statistic we perform a study on Twitter data using learning algorithms for data streams.

  8. National Stream Survey data-base guide

    SciTech Connect

    Mitch, M.E.; Kaufmann, P.R.; Herlihy, A.T.; Overton, W.S.; Sale, M.J.

    1990-07-01

    The National Stream Survey (NSS), conducted in the spring of 1985 and 1986, is one component of the U.S. Environmental Protection Agency's National Surface Water Survey. This effort is in support of the National Acid Precipitation Assessment Program. The NSS was a synoptic, spring survey of 500 streams in regions of the Southeastern and Mid-Atlantic United States expected to contain larger numbers of low alkalinity streams. The NSS is based on a probability sample from an explicitly defined population of surface waters. In the NSS, 500 streams were sampled, representing a regional population of 64,700 stream reaches. The NSS database includes stream and watershed physical characteristics, in situ measurements, and water chemistry data. Accompanying the database is a comprehensive user's guide that provides an overview of the NSS design, database structure, and transfer media.

  9. Stream bed temperature profiles as indicators of percolation characteristics beneath arroyos in the middle Rio Grande Basin, USA

    USGS Publications Warehouse

    Constantz, J.; Thomas, C.L.

    1997-01-01

    Stream bed temperature profiles were monitored continuously during water year 1990 and 1991 (WY90 and 91) in two New Mexico arroyos, similar in their meteorological features and dissimilar in their hydrological features. Stream bed temperature profiles between depths of 30 and 300 cm were examined to determine whether temporal changes in temperature profiles represent accurate indicators of the timing, depth and duration of percolation in each stream bed. These results were compared with stream flow, air temperature, and precipitation records for WY90 and 91, to evaluate the effect of changing surface conditions on temperature profiles. Temperature profiles indicate a persistently high thermal gradient with depth beneath Grantline Arroyo, except during a semi-annual thermal reversal in spring and autumn. This typifies the thermal response of dry sediments with low thermal conductivities. High thermal gradients were disrupted only during infrequent stream flows, followed by rapid re-establishment of high gradients. The stream bed temperature at 300 cm was unresponsive to individual precipitation or stream flow during WY90 and 91. This thermal pattern provides strong evidence that most seepage into Grantline Arroyo failed to percolate at a sufficient rate to reach 300 cm before being returned to the atmosphere. A distinctly different thermal pattern was recorded beneath Tijeras Arroyo. Low thermal gradients between 30 and 300 cm and large diurnal variations in temperature, suggest that stream flow created continuous, advection-dominated heat transport for over 300 days, annually. Beneath Tijeras Arroyo, low thermal gradients were interrupted only briefly during periodic, dry summer conditions. Comparisons of stream flow records for WY90 and 91 with stream bed temperature profiles indicate that independent analysis of thermal patterns provides accurate estimates of the timing, depth and duration of percolation beneath both arroyos. Stream flow loss estimates indicate

  10. Predicted effects of climate warming on the distribution of 50 stream fishes in Wisconsin, U.S.A.

    USGS Publications Warehouse

    Lyons, J.; Stewart, J.S.; Mitro, M.

    2010-01-01

    Summer air and stream water temperatures are expected to rise in the state of Wisconsin, U.S.A., over the next 50 years. To assess potential climate warming effects on stream fishes, predictive models were developed for 50 common fish species using classification-tree analysis of 69 environmental variables in a geographic information system. Model accuracy was 56.0-93.5% in validation tests. Models were applied to all 86 898 km of stream in the state under four different climate scenarios: current conditions, limited climate warming (summer air temperatures increase 1?? C and water 0.8?? C), moderate warming (air 3?? C and water 2.4?? C) and major warming (air 5?? C and water 4?? C). With climate warming, 23 fishes were predicted to decline in distribution (three to extirpation under the major warming scenario), 23 to increase and four to have no change. Overall, declining species lost substantially more stream length than increasing species gained. All three cold-water and 16 cool-water fishes and four of 31 warm-water fishes were predicted to decline, four warm-water fishes to remain the same and 23 warm-water fishes to increase in distribution. Species changes were predicted to be most dramatic in small streams in northern Wisconsin that currently have cold to cool summer water temperatures and are dominated by cold-water and cool-water fishes, and least in larger and warmer streams and rivers in southern Wisconsin that are currently dominated by warm-water fishes. Results of this study suggest that even small increases in summer air and water temperatures owing to climate warming will have major effects on the distribution of stream fishes in Wisconsin. ?? 2010 The Authors. Journal of Fish Biology ?? 2010 The Fisheries Society of the British Isles.

  11. Predicted effects of climate warming on the distribution of 50 stream fishes in Wisconsin, U.S.A.

    USGS Publications Warehouse

    Stewart, Jana S.; Lyons, John D.; Matt Mitro,

    2010-01-01

    Summer air and stream water temperatures are expected to rise in the state of Wisconsin, U.S.A., over the next 50 years. To assess potential climate warming effects on stream fishes, predictive models were developed for 50 common fish species using classification-tree analysis of 69 environmental variables in a geographic information system. Model accuracy was 56·0–93·5% in validation tests. Models were applied to all 86 898 km of stream in the state under four different climate scenarios: current conditions, limited climate warming (summer air temperatures increase 1° C and water 0·8° C), moderate warming (air 3° C and water 2·4° C) and major warming (air 5° C and water 4° C). With climate warming, 23 fishes were predicted to decline in distribution (three to extirpation under the major warming scenario), 23 to increase and four to have no change. Overall, declining species lost substantially more stream length than increasing species gained. All three cold-water and 16 cool-water fishes and four of 31 warm-water fishes were predicted to decline, four warm-water fishes to remain the same and 23 warm-water fishes to increase in distribution. Species changes were predicted to be most dramatic in small streams in northern Wisconsin that currently have cold to cool summer water temperatures and are dominated by cold-water and cool-water fishes, and least in larger and warmer streams and rivers in southern Wisconsin that are currently dominated by warm-water fishes. Results of this study suggest that even small increases in summer air and water temperatures owing to climate warming will have major effects on the distribution of stream fishes in Wisconsin.

  12. Modeling the effects of prior infection on vaccine efficacy

    SciTech Connect

    Smith, D.J.; Forrest, S.; Ackley, D.H.; Perelson, A.S.

    1997-11-01

    We performed computer simulations to study the effects of prior infection on vaccine efficacy. We injected three antigens sequentially. The first antigen, designated the prior, represented a prior infection or vaccination. The second antigen, the vaccine, represented a single component of the trivalent influenza vaccine. The third antigen, the epidemic, represented challenge by an epidemic strain. For a fixed vaccine to epidemic strain cross-reactivities to the vaccine and to the epidemic strains. We found that, for many cross-reactivities, vaccination, when it had been preceded by a prior infection, provided more protection than vaccination alone. However, at some cross-reactivities, the prior infection reduced protection by clearing the vaccine before it had the chance to produce protective memory. The cross-reactivities between the prior, vaccine and epidemic strains played a major role in determining vaccine efficacy. This work has applications to understanding vaccination against viruses such as influenza that are continually mutating.

  13. Spectrum of turbulence in a contracting stream

    NASA Technical Reports Server (NTRS)

    Ribner, H S; Tucker, M

    1953-01-01

    The spectrum concept is employed to study the selective effect of a stream contraction on the longitudinal and lateral turbulent velocity fluctuations of the stream. By a consideration of the effect of the stream contraction on a single plane sinusoidal disturbance wave, mathematically not dissimilar to a triply periodic disturbance treated by G. I. Taylor, the effect on the spectrum tensor of the turbulence and hence on the correlation tensor is determined.

  14. Stream Centerline for Fanno Creek, Oregon

    USGS Publications Warehouse

    Sobieszczyk, Steven

    2011-01-01

    Fanno Creek is a tributary to the Tualatin River and flows though parts of the southwest Portland metropolitan area. The stream is heavily influenced by urban runoff and shows characteristic flashy streamflow and poor water quality commonly associated with urban streams. This data set represents the stream centerline of the current active channel as derived from light detection and ranging (LiDAR) data and aerial photographic imagery.

  15. Assessing effects of water abstraction on fish assemblages in Mediterranean streams

    USGS Publications Warehouse

    Benejam, Lluis; Angermeier, Paul L.; Munne, Antoni; García-Berthou, Emili

    2010-01-01

    1. Water abstraction strongly affects streams in arid and semiarid ecosystems, particularly where there is a Mediterranean climate. Excessive abstraction reduces the availability of water for human uses downstream and impairs the capacity of streams to support native biota. 2. We investigated the flow regime and related variables in six river basins of the Iberian Peninsula and show that they have been strongly altered, with declining flows (autoregressive models) and groundwater levels during the 20th century. These streams had lower flows and more frequent droughts than predicted by the official hydrological model used in this region. Three of these rivers were sometimes dry, whereas there were predicted by the model to be permanently flowing. Meanwhile, there has been no decrease in annual precipitation. 3. We also investigated the fish assemblage of a stream in one of these river basins (Tordera) for 6 years and show that sites more affected by water abstraction display significant differences in four fish metrics (catch per unit effort, number of benthic species, number of intolerant species and proportional abundance of intolerant individuals) commonly used to assess the biotic condition of streams. 4. We discuss the utility of these metrics in assessing impacts of water abstraction and point out the need for detailed characterisation of the natural flow regime (and hence drought events) prior to the application of biotic indices in streams severely affected by water abstraction. In particular, in cases of artificially dry streams, it is more appropriate for regulatory agencies to assign index scores that reflect biotic degradation than to assign ‘missing’ scores, as is presently customary in assessments of Iberian streams.

  16. The hydrology of riparian buffer zones; two case studies in an ephemeral and a perennial stream

    NASA Astrophysics Data System (ADS)

    Rassam, David W.; Fellows, Christine S.; De Hayr, Robert; Hunter, Heather; Bloesch, Philip

    2006-06-01

    Riparian zones can provide a protective buffer between streams and adjacent land-based activities by removing nitrate from shallow groundwater flowing through them. Hydrological factors are an important influence on the effectiveness of riparian buffer zones in reducing pollutant loads delivered to streams. In this paper, we present results from a study of the hydrology of two riparian buffers belonging to an ephemeral and a perennial stream, which are part of a research project to study nitrogen transport and transformation processes in shallow groundwater in South-East Queensland, Australia. The investigation at the ephemeral site has shown that a shallow perched water table forms shortly after stream flow commences as a result of lateral flow from the stream to floodplain; it resides within the carbon-rich root zone and drains off after stream flow ceases. The low head gradient of 1% results in a low flow rate of about 6 cm/day along the floodplain, slow enough to allow effective removal of nitrate via denitrification to occur. The investigation at the perennial site has shown that water table dynamics within the floodplain are dissociated from the up-slope area except during over-bank flood events. During non-event conditions, there is low streamward gradient that results in a base flow component to the stream; the water table depth is about 3.5 m, hence missing most of the carbon-rich soils located close to the soil surface. During flood events, a reverse gradient towards the floodplain is formed; the streamward gradient is re-established after the flood wave passes. The water table fluctuates between 1.8 and 3.5 m under these conditions thus having a higher chance of interacting with more active floodplain sediments. Water stored in the floodplain has a residence time of 2-10 days, providing an opportunity for denitrification to reduce nitrate concentrations prior to water draining back to the stream.

  17. Compensatory stream and wetland mitigation in North Carolina: an evaluation of regulatory success.

    PubMed

    Hill, Tammy; Kulz, Eric; Munoz, Breda; Dorney, John R

    2013-05-01

    Data from a probability sample were used to estimate wetland and stream mitigation success from 2007 to 2009 across North Carolina (NC). "Success" was defined as whether the mitigation site met regulatory requirements in place at the time of construction. Analytical results were weighted by both component counts and mitigation size. Overall mitigation success (including preservation) was estimated at 74 % (SE = 3 %) for wetlands and 75 % (SE = 4 %) for streams in NC. Compared to the results of previous studies, wetland mitigation success rates had increased since the mid-1990s. Differences between mitigation providers (mitigation banks, NC Ecosystem Enhancement Program's design-bid-build and full-delivery programs, NC Department of Transportation and private permittee-responsible mitigation) were generally not significant although permittee-responsible mitigation yielded higher success rates in certain circumstances. Both wetland and stream preservation showed high rates of success and the stream enhancement success rate was significantly higher than that of stream restoration. Additional statistically significant differences when mitigation size was considered included: (1) the Piedmont yielded a lower stream mitigation success rate than other areas of the state, and (2) recently constructed wetland mitigation projects demonstrated a lower success rate than those built prior to 2002. Opportunities for improvement exist in the areas of regulatory record-keeping, understanding the relationship between post-construction establishment and long-term ecological trajectories of stream and wetland restoration projects, incorporation of numeric ecological metrics into mitigation monitoring and success criteria, and adaptation of stream mitigation designs to achieve greater success in the Piedmont.

  18. A Markov Random Field orientation prior for electronic cleansing in CT Colonography.

    PubMed

    Krishnan, Karthik; Desai, Nasir

    2015-01-01

    Tagging of the bowel content with an oral contrast facilitates CT Colonography with limited bowel preparation. Electronic colon cleansing (ECC) reconstructs the colon lumen, devoid of feces from a CT scan acquired with fecal fluid tagging. A popular method to estimate the stool composition in an image (with the purpose of removing it) is the well-established Expectation Maximization (EM) method. The tagged fluid residue appears as a contrast enhanced region with a largely horizontal interface with air above it. One of the issues is the partial volume (PV) effect that creates voxels with attenuations similar to that of the colon wall at the boundary of air and tagged fluid. We present here, a novel orientation prior formulated as a Markov Random Field that is included as part of the EM tissue segmentation framework to mitigate this PV effect at the air and tagged fluid layer. We show quantitative results on a simple synthetic dataset and qualitative results on patient data that highlight improvements due to the inclusion of the orientation prior.

  19. Interactions among forest age, valley and channel morphology, and log jams regulate animal production in mountain streams

    NASA Astrophysics Data System (ADS)

    Walters, D. M.; Venarsky, M. P.; Hall, R. O., Jr.; Herdrich, A.; Livers, B.; Winkelman, D.; Wohl, E.

    2014-12-01

    differences in stream morphology, but rather to changes in elevation and associated air temperatures. These results demonstrate strong indirect effects of forest age and valley morphometry on organic matter storage and animal secondary production in streams that is mediated by direct effects associated with the presence or absence of logjams.

  20. Numerical Simulation of Interaction of Hypervelocity Particle Stream with a Target

    NASA Astrophysics Data System (ADS)

    Lomov, Ilya; Liu, Benjamin; Georgevich, Vlad; Antoun, Tarabay

    2007-12-01

    We present results of direct numerical simulations of impact of hypervelocity particle stream with a target. The stream of interest consists of submillimeter (30-300 micron) brittle ceramic particles. Current supercomputer capabilities make it possible to simulate a realistic size of streams (up to 20 mm in diameter and 500 mm in length) while resolving each particle individually. Such simulations make possible to study the damage of the target from synergistic effects of individual impacts. In our research we fixed the velocity distribution along the axis of the stream (1-4 km/s) and volume fraction of the solid material (1-10%) and study effects of particle size variation, particle and target material properties and surrounding air properties. We ran 3D calibration simulations with up to 10 million individual particles and conducted sensitivity studies with 2D cylindrically symmetric simulations. We used an Eulerian Godunov hydrocode with adaptive mesh refinement. The particles, target material and air are represented with volume-of-fluid approach. Brittle particle and target material has been simulated with pressure-dependent yield strength and Steinberg model has been used for metal targets. Simulations demonstrated penetration depth and a hole diameter similar to experimental observations and can explain the influence of parameters of the stream on the character of the penetration.