The effect of gas and fluid flows on nonlinear lateral vibrations of rotating drill strings

NASA Astrophysics Data System (ADS)

Khajiyeva, Lelya; Kudaibergenov, Askar; Kudaibergenov, Askat

2018-06-01

In this work we develop nonlinear mathematical models describing coupled lateral vibrations of a rotating drill string under the effect of external supersonic gas and internal fluid flows. An axial compressive load and a torque also affect the drill string. The mathematical models are derived by the use of Novozhilov's nonlinear theory of elasticity with implementation of Hamilton's variation principle. Expressions for the gas flow pressure are determined according to the piston theory. The fluid flow is considered as added mass inside the curved tube of the drill string. Using an algorithm developed in the Mathematica computation program on the basis of the Galerkin approach and the stiffness switching method the numerical solution of the obtained approximate differential equations is found. Influences of the external loads, drill string angular speed of rotation, parameters of the gas and fluid flows on the drill string vibrations are shown.

Nonlinear Convective Flows in a Laterally Heated Two-Layer System with a Temperature-Dependent Heat Release/Consumption at the Interface

NASA Astrophysics Data System (ADS)

Simanovskii, Ilya; Viviani, Antonio; Dubois, Frank; Queeckers, Patrick

2018-01-01

Nonlinear convective flows developed under the joint action of buoyant and thermocapillary effects in a laterally heated two-layer system filling the closed cavity, have been investigated. The influence of a temperature-dependent interfacial heat release/consumption on nonlinear steady and oscillatory regimes, has been studied. It is shown that sufficiently strong temperature dependence of interfacial heat sinks and heat sources can change the sequence of bifurcations and lead to the development of specific oscillatory regimes in the system.

Novel approach based on one-tube nested PCR and a lateral flow strip for highly sensitive diagnosis of tuberculous meningitis.

PubMed

Sun, Yajuan; Chen, Jiajun; Li, Jia; Xu, Yawei; Jin, Hui; Xu, Na; Yin, Rui; Hu, Guohua

2017-01-01

Rapid and sensitive detection of Mycobacterium tuberculosis (M. Tb) in cerebrospinal fluid is crucial in the diagnosis of tuberculous meningitis (TBM), but conventional diagnostic technologies have limited sensitivity and specificity or are time-consuming. In this work, a novel, highly sensitive molecular diagnostic method, one-tube nested PCR-lateral flow strip test (OTNPCR-LFST), was developed for detecting M. tuberculosis. This one-tube nested PCR maintains the sensitivity of conventional two-step nested PCR and reduces both the chance of cross-contamination and the time required for analysis. The PCR product was detected by a lateral flow strip assay, which provided a basis for migration of the test to a point-of-care (POC) microfluidic format. The developed assay had an improved sensitivity compared with traditional PCR, and the limit of detection was up to 1 fg DNA isolated from M. tuberculosis. The assay was also specific for M. tuberculosis, and no cross-reactions were found in other non-target bacteria. The application of this technique to clinical samples was successfully evaluated, and OTNPCR-LFST showed 89% overall sensitivity and 100% specificity for TBM patients. This one-tube nested PCR-lateral flow strip assay is useful for detecting M. tuberculosis in TBM due to its rapidity, high sensitivity and simple manipulation.

A Novel Quantum Dots-Based Point of Care Test for Syphilis

NASA Astrophysics Data System (ADS)

Yang, Hao; Li, Ding; He, Rong; Guo, Qin; Wang, Kan; Zhang, Xueqing; Huang, Peng; Cui, Daxiang

2010-05-01

One-step lateral flow test is recommended as the first line screening of syphilis for primary healthcare settings in developing countries. However, it generally shows low sensitivity. We describe here the development of a novel fluorescent POC (Point Of Care) test method to be used for screening for syphilis. The method was designed to combine the rapidness of lateral flow test and sensitiveness of fluorescent method. 50 syphilis-positive specimens and 50 healthy specimens conformed by Treponema pallidum particle agglutination (TPPA) were tested with Quantum Dot-labeled and colloidal gold-labeled lateral flow test strips, respectively. The results showed that both sensitivity and specificity of the quantum dots-based method reached up to 100% (95% confidence interval [CI], 91-100%), while those of the colloidal gold-based method were 82% (95% CI, 68-91%) and 100% (95% CI, 91-100%), respectively. In addition, the naked-eye detection limit of quantum dot-based method could achieve 2 ng/ml of anti-TP47 polyclonal antibodies purified by affinity chromatography with TP47 antigen, which was tenfold higher than that of colloidal gold-based method. In conclusion, the quantum dots were found to be suitable for labels of lateral flow test strip. Its ease of use, sensitiveness and low cost make it well-suited for population-based on-the-site syphilis screening.

A detached eddy simulation model for the study of lateral separation zones along a large canyon-bound river

NASA Astrophysics Data System (ADS)

Alvarez, Laura V.; Schmeeckle, Mark W.; Grams, Paul E.

2017-01-01

Lateral flow separation occurs in rivers where banks exhibit strong curvature. In canyon-bound rivers, lateral recirculation zones are the principal storage of fine-sediment deposits. A parallelized, three-dimensional, turbulence-resolving model was developed to study the flow structures along lateral separation zones located in two pools along the Colorado River in Marble Canyon. The model employs the detached eddy simulation (DES) technique, which resolves turbulence structures larger than the grid spacing in the interior of the flow. The DES-3D model is validated using Acoustic Doppler Current Profiler flow measurements taken during the 2008 controlled flood release from Glen Canyon Dam. A point-to-point validation using a number of skill metrics, often employed in hydrological research, is proposed here for fluvial modeling. The validation results show predictive capabilities of the DES model. The model reproduces the pattern and magnitude of the velocity in the lateral recirculation zone, including the size and position of the primary and secondary eddy cells, and return current. The lateral recirculation zone is open, having continuous import of fluid upstream of the point of reattachment and export by the recirculation return current downstream of the point of separation. Differences in magnitude and direction of near-bed and near-surface velocity vectors are found, resulting in an inward vertical spiral. Interaction between the recirculation return current and the main flow is dynamic, with large temporal changes in flow direction and magnitude. Turbulence structures with a predominately vertical axis of vorticity are observed in the shear layer becoming three-dimensional without preferred orientation downstream.

Development of a Rapid Immunochromatographic Lateral Flow Device Capable of Differentiating Phytase Expressed from Recombinant Aspergillus niger phyA2 and Genetically Modified Corn.

PubMed

Zhou, Xiaojin; Hui, Elizabeth; Yu, Xiao-Lin; Lin, Zhen; Pu, Ling-Kui; Tu, Zhiguan; Zhang, Jun; Liu, Qi; Zheng, Jian; Zhang, Juan

2015-05-06

Phytase is a phosphohydrolase considered highly specific for the degradation of phytate to release bound phosphorus for animal consumption and aid in the reduction of environmental nutrient loading. New sources of phytase have been sought that are economically and efficiently productive including the construction of genetically modified (GM) phytase products designed to bypass the costs associated with feed processing. Four monoclonal antibodies (EH10a, FA7, AF9a, and CC1) raised against recombinant Aspergillus niger phyA2 were used to develop a highly specific and sensitive immunochromatographic lateral flow device for rapid detection of transgenic phytase, such as in GM corn. Antibodies sequentially paired and tested along lateral flow strips showed that the EH10a-FA7 antibody pair was able to detect the recombinant yeast-phytase at 5 ng/mL, whereas the AF9a-CC1 antibody pair to GM phytase corn was able to detect at 2 ng/mL. Concurrent to this development, evidence was revealed which suggests that antibody binding sites may be glycosylated.

A bio-inspired real-time capable artificial lateral line system for freestream flow measurements.

PubMed

Abels, C; Qualtieri, A; De Vittorio, M; Megill, W M; Rizzi, F

2016-06-03

To enhance today's artificial flow sensing capabilities in aerial and underwater robotics, future robots could be equipped with a large number of miniaturized sensors distributed over the surface to provide high resolution measurement of the surrounding fluid flow. In this work we show a linear array of closely separated bio-inspired micro-electro-mechanical flow sensors whose sensing mechanism is based on a piezoresistive strain-gauge along a stress-driven cantilever beam, mimicking the biological superficial neuromasts found in the lateral line organ of fishes. Aiming to improve state-of-the-art flow sensing capability in autonomously flying and swimming robots, our artificial lateral line system was designed and developed to feature multi-parameter freestream flow measurements which provide information about (1) local flow velocities as measured by the signal amplitudes from the individual cantilevers as well as (2) propagation velocity, (3) linear forward/backward direction along the cantilever beam orientation and (4) periodicity of pulses or pulse trains determined by cross-correlating sensor signals. A real-time capable cross-correlation procedure was developed which makes it possible to extract freestream flow direction and velocity information from flow fluctuations. The computed flow velocities deviate from a commercial system by 0.09 m s(-1) at 0.5 m s(-1) and 0.15 m s(-1) at 1.0 m s(-1) flow velocity for a sampling rate of 240 Hz and a sensor distance of 38 mm. Although experiments were performed in air, the presented flow sensing system can be applied to underwater vehicles as well, once the sensors are embedded in a waterproof micro-electro-mechanical systems package.

A Gradually Varied Approach to Model Turbidity Currents in Submarine Channels

NASA Astrophysics Data System (ADS)

Bolla Pittaluga, M.; Frascati, A.; Falivene, O.

2018-01-01

We develop a one-dimensional model to describe the dynamics of turbidity current flowing in submarine channels. We consider the flow as a steady state polydisperse suspension accounting for water detrainment from the clear water-turbid interface, for spatial variations of the channel width and for water and sediment lateral overspill from the channel levees. Moreover, we account for sediment exchange with the bed extending the model to deal with situations where the current meets a nonerodible bed. Results show that when water detrainment is accounted for, the flow thickness becomes approximately constant proceeding downstream. Similarly, in the presence of channel levees, the flow tends to adjust to channel relief through the lateral loss of water and sediment. As more mud is spilled above the levees relative to sand, the flow becomes more sand rich proceeding downstream when lateral overspill is present. Velocity and flow thickness predicted by the model are then validated by showing good agreement with laboratory observations. Finally, the model is applied to the Monterey Canyon bathymetric data matching satisfactorily the December 2002 event field measurements and predicting a runout length consistent with observations.

Novel approach based on one-tube nested PCR and a lateral flow strip for highly sensitive diagnosis of tuberculous meningitis

PubMed Central

Sun, Yajuan; Chen, Jiajun; Li, Jia; Xu, Yawei; Jin, Hui; Xu, Na; Yin, Rui

2017-01-01

Rapid and sensitive detection of Mycobacterium tuberculosis (M. Tb) in cerebrospinal fluid is crucial in the diagnosis of tuberculous meningitis (TBM), but conventional diagnostic technologies have limited sensitivity and specificity or are time-consuming. In this work, a novel, highly sensitive molecular diagnostic method, one-tube nested PCR-lateral flow strip test (OTNPCR-LFST), was developed for detecting M. tuberculosis. This one-tube nested PCR maintains the sensitivity of conventional two-step nested PCR and reduces both the chance of cross-contamination and the time required for analysis. The PCR product was detected by a lateral flow strip assay, which provided a basis for migration of the test to a point-of-care (POC) microfluidic format. The developed assay had an improved sensitivity compared with traditional PCR, and the limit of detection was up to 1 fg DNA isolated from M. tuberculosis. The assay was also specific for M. tuberculosis, and no cross-reactions were found in other non-target bacteria. The application of this technique to clinical samples was successfully evaluated, and OTNPCR-LFST showed 89% overall sensitivity and 100% specificity for TBM patients. This one-tube nested PCR-lateral flow strip assay is useful for detecting M. tuberculosis in TBM due to its rapidity, high sensitivity and simple manipulation. PMID:29084241

Rapid visual detection of cyprinid herpesvirus 2 by recombinase polymerase amplification combined with a lateral flow dipstick.

PubMed

Wang, H; Sun, M; Xu, D; Podok, P; Xie, J; Jiang, Ys; Lu, Lq

2018-05-28

Herpesviral haematopoietic necrosis (HVHN), caused by cyprinid herpesvirus 2 (CyHV-2), causes significant losses in crucian carp (Carassius carassius) aquaculture. Rapid and convenient DNA assay detection of CyHV-2 is useful for field diagnosis. Recombinase polymerase amplification (RPA) is a novel isothermal DNA amplification and detection technology that can amplify DNA within 30 min at ~37°C by simulating in vivo DNA recombination. Herein, a rapid and convenient detection assay based on RPA with a lateral flow dipstick (LFD) was developed for detecting CyHV-2. The highly conserved ORF72 of CyHV-2 was targeted by specific and sensitive primers and probes. The optimized assay takes only 15 min at 38°C using a water bath, with analysis of products by 2% agarose gel electrophoresis within 30 min. A simple lateral flow strip based on the unique probe in reaction buffer was developed for visualization. The entire RPA-LFD assay takes 50 min less than the routine PCR method, is 100 times more sensitive and displays no cross-reaction with other aquatic viruses. The combined isothermal RPA and lateral flow assay (RPA-LFD) provides a simple, rapid, reliable method that could improve field diagnosis of CyHV-2 when resources are limited. © 2018 John Wiley & Sons Ltd.

A lateral electrophoretic flow diagnostic assay

PubMed Central

Lin, Robert; Skandarajah, Arunan; Gerver, Rachel E.; Neira, Hector D.; Fletcher, Daniel A.

2015-01-01

Immunochromatographic assays are a cornerstone tool in disease screening. To complement existing lateral flow assays (based on wicking flow) we introduce a lateral flow format that employs directed electrophoretic transport. The format is termed a “lateral e-flow assay” and is designed to support multiplexed detection using immobilized reaction volumes of capture antigen. To fabricate the lateral e-flow device, we employ mask-based UV photopatterning to selectively immobilize unmodified capture antigen along the microchannel in a barcode-like pattern. The channel-filling polyacrylamide hydrogel incorporates a photoactive moiety (benzophenone) to immobilize capture antigen to the hydrogel without a priori antigen modification. We report a heterogeneous sandwich assay using low-power electrophoresis to drive biospecimen through the capture antigen barcode. Fluorescence barcode readout is collected via a low-resource appropriate imaging system (CellScope). We characterize lateral e-flow assay performance and demonstrate a serum assay for antibodies to the hepatitis C virus (HCV). In a pilot study, the lateral e-flow assay positively identifies HCV+ human sera in 60 min. The lateral e-flow assay provides a flexible format for conducting multiplexed immunoassays relevant to confirmatory diagnosis in near-patient settings. PMID:25608872

Electrochemical lateral flow immunosensor for detection and quantification of dengue NS1 protein.

PubMed

Sinawang, Prima Dewi; Rai, Varun; Ionescu, Rodica E; Marks, Robert S

2016-03-15

An Electrochemical Lateral Flow Immunosensor (ELFI) is developed combining screen-printed gold electrodes (SPGE) enabling quantification together with the convenience of a lateral flow test strip. A cellulose glassy fiber paper conjugate pad retains the marker immunoelectroactive nanobeads which will bind to the target analyte of interest. The specific immunorecognition event continues to occur along the lateral flow bed until reaching the SPGE-capture antibodies at the end of the cellulosic lateral flow strip. The rationale of the immunoassay consists in the analyte antigen NS1 protein being captured selectively and specifically by the dengue NS1 antibody conjugated onto the immunonanobeads thus forming an immunocomplex. With the aid of a running buffer, the immunocomplexes flow and reach the immuno-conjugated electrode surface and form specific sandwich-type detection due to specific, molecular recognition, while unbound beads move along past the electrodes. The successful sandwich immunocomplex formation is then recorded electrochemically. Specific detection of NS1 is translated into an electrochemical signal contributed by a redox label present on the bead-immobilized detection dengue NS1 antibody while a proportional increase of faradic current is observed with increase in analyte NS1 protein concentration. The first generation ELFI prototype is simply assembled in a cassette and successfully demonstrates wide linear range over a concentration range of 1-25 ng/mL with an ultrasensitive detection limit of 0.5 ng/mL for the qualitative and quantitative detection of analyte dengue NS1 protein. Copyright © 2015 Elsevier B.V. All rights reserved.

Analytical Tools to Improve Optimization Procedures for Lateral Flow Assays

PubMed Central

Hsieh, Helen V.; Dantzler, Jeffrey L.; Weigl, Bernhard H.

2017-01-01

Immunochromatographic or lateral flow assays (LFAs) are inexpensive, easy to use, point-of-care medical diagnostic tests that are found in arenas ranging from a doctor’s office in Manhattan to a rural medical clinic in low resource settings. The simplicity in the LFA itself belies the complex task of optimization required to make the test sensitive, rapid and easy to use. Currently, the manufacturers develop LFAs by empirical optimization of material components (e.g., analytical membranes, conjugate pads and sample pads), biological reagents (e.g., antibodies, blocking reagents and buffers) and the design of delivery geometry. In this paper, we will review conventional optimization and then focus on the latter and outline analytical tools, such as dynamic light scattering and optical biosensors, as well as methods, such as microfluidic flow design and mechanistic models. We are applying these tools to find non-obvious optima of lateral flow assays for improved sensitivity, specificity and manufacturing robustness. PMID:28555034

Highly simplified lateral flow-based nucleic acid sample preparation and passive fluid flow control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cary, Robert E.

2015-12-08

Highly simplified lateral flow chromatographic nucleic acid sample preparation methods, devices, and integrated systems are provided for the efficient concentration of trace samples and the removal of nucleic acid amplification inhibitors. Methods for capturing and reducing inhibitors of nucleic acid amplification reactions, such as humic acid, using polyvinylpyrrolidone treated elements of the lateral flow device are also provided. Further provided are passive fluid control methods and systems for use in lateral flow assays.

Highly simplified lateral flow-based nucleic acid sample preparation and passive fluid flow control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cary, Robert B.

Highly simplified lateral flow chromatographic nucleic acid sample preparation methods, devices, and integrated systems are provided for the efficient concentration of trace samples and the removal of nucleic acid amplification inhibitors. Methods for capturing and reducing inhibitors of nucleic acid amplification reactions, such as humic acid, using polyvinylpyrrolidone treated elements of the lateral flow device are also provided. Further provided are passive fluid control methods and systems for use in lateral flow assays.

Rapid detection of Bacillus anthracis spores using a super-paramagnetic lateral-flow immunological detection system.

PubMed

Wang, Dian-Bing; Tian, Bo; Zhang, Zhi-Ping; Deng, Jiao-Yu; Cui, Zong-Qiang; Yang, Rui-Fu; Wang, Xu-Ying; Wei, Hong-Ping; Zhang, Xian-En

2013-04-15

There is an urgent need for convenient, sensitive, and specific methods to detect the spores of Bacillus anthracis, the causative agent of anthrax, because of the bioterrorism threat posed by this bacterium. In this study, we firstly develop a super-paramagnetic lateral-flow immunological detection system for B. anthracis spores. This system involves the use of a portable magnetic assay reader, super-paramagnetic iron oxide particles, lateral-flow strips and two different monoclonal antibodies directed against B. anthracis spores. This detection system specifically recognises as few as 400 pure B. anthracis spores in 30 min. This system has a linear range of 4×10³-10⁶ CFU ml⁻¹ and reproducible detection limits of 200 spores mg⁻¹ milk powder and 130 spores mg⁻¹ soil for simulated samples. In addition, this approach shows no obvious cross-reaction with other related Bacillus spores, even at high concentrations, and has no significant dependence on the duration of the storage of the immunological strips. Therefore, this super-paramagnetic lateral-flow immunological detection system is a promising tool for the rapid and sensitive detection of Bacillus anthracis spores under field conditions. Copyright © 2012 Elsevier B.V. All rights reserved.

Development and application of a hillslope hydrologic model

USGS Publications Warehouse

Blain, C.A.; Milly, P.C.D.

1991-01-01

A vertically integrated two-dimensional lateral flow model of soil moisture has been developed. Derivation of the governing equation is based on a physical interpretation of hillslope processes. The lateral subsurface-flow model permits variability of precipitation and evapotranspiration, and allows arbitrary specification of soil-moisture retention properties. Variable slope, soil thickness, and saturation are all accommodated. The numerical solution method, a Crank-Nicolson, finite-difference, upstream-weighted scheme, is simple and robust. A small catchment in northeastern Kansas is the subject of an application of the lateral subsurface-flow model. Calibration of the model using observed discharge provides estimates of the active porosity (0.1 cm3/cm3) and of the saturated horizontal hydraulic conductivity (40 cm/hr). The latter figure is at least an order of magnitude greater than the vertical hydraulic conductivity associated with the silty clay loam soil matrix. The large value of hydraulic conductivity derived from the calibration is suggestive of macropore-dominated hillslope drainage. The corresponding value of active porosity agrees well with a published average value of the difference between total porosity and field capacity for a silty clay loam. ?? 1991.

Sensitive Detection of Norovirus Using Phage Nanoparticle Reporters in Lateral-Flow Assay

PubMed Central

Hagström, Anna E. V.; Garvey, Gavin; Paterson, Andrew S.; Dhamane, Sagar; Adhikari, Meena; Estes, Mary K.; Strych, Ulrich; Kourentzi, Katerina; Atmar, Robert L.; Willson, Richard C.

2015-01-01

Noroviruses are recognized worldwide as the principal cause of acute, non-bacterial gastroenteritis, resulting in 19-21 million cases of disease every year in the United States. Noroviruses have a very low infectious dose, a short incubation period, high resistance to traditional disinfection techniques and multiple modes of transmission, making early, point-of-care detection essential for controlling the spread of the disease. The traditional diagnostic tools, electron microscopy, RT-PCR and ELISA require sophisticated and expensive instrumentation, and are considered too laborious and slow to be useful during severe outbreaks. In this paper we describe the development of a new, rapid and sensitive lateral-flow assay using labeled phage particles for the detection of the prototypical norovirus GI.1 (Norwalk), with a limit of detection of 107 virus-like particles per mL, one hundred-fold lower than a conventional gold nanoparticle lateral-flow assay using the same antibody pair. PMID:25978622

Hypogenic origin, geologic controls and functional organization of a giant cave system in Precambrian carbonates, Brazil

NASA Astrophysics Data System (ADS)

Klimchouk, Alexander; Auler, Augusto S.; Bezerra, Francisco H. R.; Cazarin, Caroline L.; Balsamo, Fabrizio; Dublyansky, Yuri

2016-01-01

This study is focused on speleogenesis of the Toca da Boa Vista (TBV) and Toca da Barriguda (TBR), the longest caves in South America occurring in the Neoproterozoic Salitre Formation in the São Francisco Craton, NE Brazil. We employ a multidisciplinary approach integrating detailed speleomorphogenetic, lithostratigraphic and geological structure studies in order to reveal the origin of the caves, their functional organization and geologic controls on their development. The caves developed in deep-seated confined conditions by rising flow. The overall fields of passages of TBV and TBR caves represent a speleogenetically exploited large NE-SW-trending fracture corridor associated with a major thrust. This corridor vertically extends across the Salitre Formation allowing the rise of deep fluids. In the overall ascending flow system, the formation of the cave pattern was controlled by a system of sub-parallel anticlines and troughs with NNE-SSW dominant orientation, and by vertical and lateral heterogeneities in fracture distribution. Three cave-stratigraphic stories reflect the actual hydrostratigraphy during the main phase of speleogenesis. Cavities at different stories are distinct in morphology and functioning. The gross tree-dimensional pattern of the system is effectively organized to conduct rising flow in deep-seated confined conditions. Cavities in the lower story developed as recharge components to the system. A laterally extensive conduit network in the middle story formed because the vertical flow from numerous recharge points has been redirected laterally along the highly conductive unit, occurring below the major seal - a scarcely fractured unit. Rift-like and shaft-like conduits in the upper story developed along fracture-controlled outflow paths, breaching the integrity of the major seal, and served as outlets for the cave system. The cave system represents a series of vertically organized, functionally largely independent clusters of cavities developed within individual ascending flow cells. Lateral integration of clusters occurred due to hydrodynamic interaction between the flow cells in course of speleogenetic evolution and change of boundary conditions. The main speleogenetic phase, during which the gross cave pattern has been established and the caves acquired most of their volume, was likely related to rise of deep fluids at about 520 Ma or associated with rifting and the Pangea break-up in Triassic-Cretaceous. This study highlights the importance of speleogenetic studies for interpreting porosity and permeability features in carbonate reservoirs.

A Study of the Flow Structure of Tip Vortices on a Hydrofoil

DTIC Science & Technology

1986-11-28

as measured from the flow visualization imager. . . 0 . . . 61 III.10 The vertical location of the tip vortex center as measured from the flow...pressure gra- dients of opposite sign exist on both sides of an airfoil . These gradients induce an inward lateral flow on the suc- tion side and an...And most recently, Cebeci et al. (1986) developed a viscous/inviscid interaction method to calculate the flow around airfoils , emphasizing the

Flow Induced Spring Coefficients of Labyrinth Seals for Application in Rotor Dynamics

NASA Technical Reports Server (NTRS)

Benckert, H.; Wachter, J.

1980-01-01

Flow induced aerodynamic spring coefficients of labyrinth seals are discussed and the restoring force in the deflection plane of the rotor and the lateral force acting perpendicularly to it are also considered. The effects of operational conditions on the spring characteristics of these components are examined, such as differential pressure, speed, inlet flow conditions, and the geometry of the labyrinth seals. Estimation formulas for the lateral forces due to shaft rotation and inlet swirl, which are developed through experiments, are presented. The utilization of the investigations is explained and results of stability calculations, especially for high pressure centrifugal compressors, are added. Suggestions are made concerning the avoidance of exciting forces in labyrinths.

Rapid Salmonella detection in experimentally inoculated equine faecal and veterinary hospital environmental samples using commercially available lateral flow immunoassays.

PubMed

Burgess, B A; Noyes, N R; Bolte, D S; Hyatt, D R; van Metre, D C; Morley, P S

2015-01-01

Salmonella enterica is the most commonly reported cause of outbreaks of nosocomial infections in large animal veterinary teaching hospitals and the closure of equine hospitals. Rapid detection may facilitate effective control practices in equine populations. Shipping and laboratory testing typically require ≥48 h to obtain results. Lateral flow immunoassays developed for use in food-safety microbiology provide an alternative that has not been evaluated for use with faeces or environmental samples. We aimed to identify enrichment methods that would allow commercially available rapid Salmonella detection systems (lateral flow immunoassays) to be used in clinical practice with equine faecal and environmental samples, providing test results in 18-24 h. In vitro experiment. Equine faecal and environmental samples were inoculated with known quantities of S. enterica serotype Typhimurium and cultured using 2 different enrichment techniques for faeces and 4 enrichment techniques for environmental samples. Samples were tested blindly using 2 different lateral flow immunoassays and plated on agar media for confirmatory testing. In general, commercial lateral flow immunoassays resulted in fewer false-negative test results with enrichment of 1 g faecal samples in tetrathionate for 18 h, while all environmental sample enrichment techniques resulted in similar detection rates. The limit of detection from spiked samples, ∼4 colony-forming units/g, was similar for all methods evaluated. The lateral flow immunoassays evaluated could reliably detect S. enterica within 18 h, indicating that they may be useful for rapid point-of-care testing in equine practice applications. Additional evaluation is needed using samples from naturally infected cases and the environment to gain an accurate estimate of test sensitivity and specificity and to substantiate further the true value of these tests in clinical practice. © 2014 EVJ Ltd.

A high-resolution land model coupled with groundwater lateral flow, human water regulation and the changes in soil freeze-thaw fronts

NASA Astrophysics Data System (ADS)

Xie, Z.; Zeng, Y.; Liu, S.; Gao, J.; Jia, B.; Qin, P.

2017-12-01

Both anthropogenic water regulation and groundwater lateral flow essentially affect groundwater table patterns. Their relationship is close because lateral flow recharges the groundwater depletion cone, which is induced by over-exploitation. And the movement of frost and thaw fronts (FTFs) affects soil water and thermal characteristics, as well as energy and water exchanges between land surface and the atmosphere. In this study, schemes describing groundwater lateral flow, human water regulation and the changes in soil freeze-thaw fronts were developed and incorporated into the Community Land Model 4.5. Then the model was applied in Heihe River Basin(HRB), an arid and semiarid region, northwest China. High resolution ( 1 km) numerical simulations showed that groundwater lateral flow driven by changes in water heads can essentially change the groundwater table pattern with the deeper water table appearing in the hillslope regions and shallower water table appearing in valley bottom regions and plains. Over the last decade, anthropogenic groundwater exploitation deepened the water table by approximately 2 m in the middle reaches of the HRB and rapidly reduced the terrestrial water storage, while irrigation increased soil moisture by approximately 0.1 m3 m-3. The water stored in the mainstream of the Heihe River was also reduced by human surface water withdrawal. The latent heat flux was increased by 30 W m-2 over the irrigated region, with an identical decrease in sensible heat flux. The simulated groundwater lateral flow was shown to effectively recharge the groundwater depletion cone caused by over-exploitation. The offset rate is higher in plains than mountainous regions. In addition, the simulated FTFs depth compared well with the observed data both in D66 station (permafrost) and Hulugou station (seasonally frozen ground). Over the HRB, the upstream area is permafrost region with maximum thawed depth at 2.5 m and lower region is seasonal frozen ground region with maximum frozen depth at 3 m.

Significance of Bioturbated Layer (BTL) and Deep Groundwater Storage on Runoff in Steep Saprolitic Tropical Lowlands Catchment

NASA Astrophysics Data System (ADS)

Cheng, Y.; Ogden, F. L.; Zhu, J.

2016-12-01

Bioturbated soil layers (BTLs) play a significant role in hydrological response and provisioning of ecosystem services in steep, saprolitic, tropical lowlands catchments. In this study, a new physically-based model formulation was developed for testing of runoff generation hypotheses. A main feature in the model formulation is explicit simulation of hydrological processes in the BTL including macropores, which our field observations show are ubiquitous, and deep groundwater stores that provide streamflow during the dry season The numerical model developed includes two main flow paths in the BTL, including one-dimensional (1D) vertical infiltration and two-dimensional (2D) lateral flows in both macropores and the soil matrix. Hydrological processes incorporated along with the BTL processes include intercepted rainfall, evapotranspiration, 2D surface flow and 1D deep groundwater discharge. This model was first tested in a 6.5 ha secondary succession catchment, that is under study by the Smithsonian Tropical Research Institute, Agua Salud project in Panama, which is dominated by steep slopes. With the incorporation of lateral macropore flow mechanism in the BTL, the model performs better than only including soil matrix flow in the BTL especially in simulating baseflow dynamics, which illustrates the importance of preferential flow from the BTL to stream discharge dynamics. The increase in the BTL thickness promotes more flow through the BTL and increases storage in both the BTL and the deep groundwater reservoir, but decreases the total streamflow and overland flow. Lateral macropore diameter distribution influences flows more than the macropore number or distribution type. The model has thus far passed falsification tests during the early wet season. Complexity in subsurface storage and base flow generation offer a new challenge for this model. The overall objective is to develop a model formulation that is useful in practical applications related to land-use management, provisioning of ecosystem services, and water security in similar tropical settings with distinct dry and wet seasons or in the humid tropics during periods of drought.

Replacing antibodies with aptamers in lateral flow immunoassay.

PubMed

Chen, Ailiang; Yang, Shuming

2015-09-15

Aptamers have been identified against various targets as a type of chemical or nucleic acid ligand by systematic evolution of ligands by exponential enrichment (SELEX) with high sensitivity and specificity. Aptamers show remarkable advantages over antibodies due to the nucleic acid nature and target-induced structure-switching properties and are widely used to design various fluorescent, electrochemical, or colorimetric biosensors. However, the practical applications of aptamer-based sensing and diagnostics are still lagging behind those of antibody-based tests. Lateral flow immunoassay (LFIA) represents a well established and appropriate technology among rapid assays because of its low cost and user-friendliness. The antibody-based platform is utilized to detect numerous targets, but it is always hampered by the antibody preparation time, antibody stability, and effect of modification on the antibody. Seeking alternatives to antibodies is an area of active research and is of tremendous importance. Aptamers are receiving increasing attention in lateral flow applications because of a number of important potential performance advantages. We speculate that aptamer-based LFIA may be one of the first platforms for commercial use of aptamer-based diagnosis. This review first gives an introduction to aptamer including the selection process SELEX with its focus on aptamer advantages over antibodies, and then depicts LFIA with its focus on aptamer opportunities in LFIA over antibodies. Furthermore, we summarize the recent advances in the development of aptamer-based lateral flow biosensing assays with the aim to provide a general guide for the design of aptamer-based lateral flow biosensing assays. Copyright © 2015 Elsevier B.V. All rights reserved.

Multi-Nozzle Base Flow Model in the 10- by 10-Foot Supersonic Wind Tunnel

NASA Image and Video Library

1964-02-21

Researchers check the setup of a multi-nozzle base flow model in the 10- by 10-Foot Supersonic Wind Tunnel at the National Aeronautics and Space Administration (NASA) Lewis Research Center. NASA researchers were struggling to understand the complex flow phenomena resulting from the use of multiple rocket engines. Robert Wasko and Theodore Cover of the Advanced Development and Evaluation Division’s analysis and operations sections conducted a set of tests in the 10- by 10 tunnel to further understand the flow issues. The Lewis researchers studied four and five-nozzle configurations in the 10- by 10 at simulated altitudes from 60,000 to 200,000 feet. The nozzles were gimbaled during some of the test runs to simulate steering. The flow field for the four-nozzle clusters was surveyed in the center and the lateral areas between the nozzles, whereas the five-nozzle cluster was surveyed in the lateral area only.

Isothermal Recombinase Polymerase amplification (RPA) of Schistosoma haematobium DNA and oligochromatographic lateral flow detection.

PubMed

Rosser, A; Rollinson, D; Forrest, M; Webster, B L

2015-09-04

Accurate diagnosis of urogenital schistosomiasis is vital for surveillance/control programs. Amplification of schistosome DNA in urine by PCR is sensitive and specific but requires infrastructure, financial resources and skilled personnel, often not available in endemic areas. Recombinase Polymerase Amplification (RPA) is an isothermal DNA amplification/detection technology that is simple, rapid, portable and needs few resources. Here a Schistosoma haematobium RPA assay was developed and adapted so that DNA amplicons could be detected using oligochromatographic Lateral Flow (LF) strips. The assay successfully amplified S. haematobium DNA at 30-45 °C in 10 mins and was sensitive to a lower limit of 100 fg of DNA. The assay was also successful with the addition of crude urine, up to 5% of the total reaction volume. Cross amplification occurred with other schistosome species but not with other common urine microorganisms. The LF-RPA assay developed here can amplify and detect low levels of S. haematobium DNA. Reactions are rapid, require low temperatures and positive reactions are interpreted using lateral flow strips, reducing the need for infrastructure and resources. This together with an ability to withstand inhibitors within urine makes RPA a promising technology for further development as a molecular diagnostic tool for urogenital schistosomiasis.

Performance characterization of a cross-flow hydrokinetic turbine in sheared inflow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forbush, Dominic; Polagye, Brian; Thomson, Jim

2016-12-01

A method for constructing a non-dimensional performance curve for a cross-flow hydrokinetic turbine in sheared flow is developed for a natural river site. The river flow characteristics are quasi-steady, with negligible vertical shear, persistent lateral shear, and synoptic changes dominated by long time scales (days to weeks). Performance curves developed from inflow velocities measured at individual points (randomly sampled) yield inconclusive turbine performance characteristics because of the spatial variation in mean flow. Performance curves using temporally- and spatially-averaged inflow velocities are more conclusive. The implications of sheared inflow are considered in terms of resource assessment and turbine control.

Development of a transferline connecting a helium liquefier coldbox and a liquid helium Dewar

NASA Astrophysics Data System (ADS)

Menon, Rajendran S.; Rane, Tejas; Chakravarty, Anindya; Joemon, V.

2017-02-01

A helium liquefier with demonstrated capacity of 32 1/hr has been developed by BARC. Mumbai. A transferline for two way flow of helium between the helium liquefier coldbox and receiver Dewar has been developed in-house at BARC. Further, a functionally similar, but structurally improved transferline has been developed through a local fabricator. This paper describes and discusses issues related to the development of these cryogenic transferlines. The developed transferlines have been tested with a flow of liquid nitrogen and successfully utilised later in the helium liquefier plant.

Variable parameter McCarthy-Muskingum routing method considering lateral flow

NASA Astrophysics Data System (ADS)

Yadav, Basant; Perumal, Muthiah; Bardossy, Andras

2015-04-01

The fully mass conservative variable parameter McCarthy-Muskingum (VPMM) method recently proposed by Perumal and Price (2013) for routing floods in channels and rivers without considering lateral flow is extended herein for accounting uniformly distributed lateral flow contribution along the reach. The proposed procedure is applied for studying flood wave movement in a 24.2 km river stretch between Rottweil and Oberndorf gauging stations of Neckar River in Germany wherein significant lateral flow contribution by intermediate catchment rainfall prevails during flood wave movement. The geometrical elements of the cross-sectional information of the considered routing river stretch without considering lateral flow are estimated using the Robust Parameter Estimation (ROPE) algorithm that allows for arriving at the best performing set of bed width and side slope of a trapezoidal section. The performance of the VPMM method is evaluated using the Nash-Sutcliffe model efficiency criterion as the objective function to be maximized using the ROPE algorithm. The twenty-seven flood events in the calibration set are considered to identify the relationship between 'total rainfall' and 'total losses' as well as to optimize the geometric characteristics of the prismatic channel (width and slope of the trapezoidal section). Based on this analysis, a relationship between total rainfall and total loss of the intermediate catchment is obtained and then used to estimate the lateral flow in the reach. Assuming the lateral flow hydrograph is of the form of inflow hydrograph and using the total intervening catchment runoff estimated from the relationship, the uniformly distributed lateral flow rate qL at any instant of time is estimated for its use in the VPMM routing method. All the 27 flood events are simulated using this routing approach considering lateral flow along the reach. Many of these simulations are able to simulate the observed hydrographs very closely. The proposed approach of accounting lateral flow using the VPMM method is independently verified by routing flood hydrograph of 6 flood events which are not used in the total rainfall vs total loss relationship established for the intervening catchment of the studied river reach. Close reproduction of the outflow hydrographs of these independent events using the proposed VPMM method accounting for lateral flow demonstrate the practical utility of the method.

Economic evaluation of laboratory testing strategies for hospital-associated Clostridium difficile infection.

PubMed

Schroeder, Lee F; Robilotti, Elizabeth; Peterson, Lance R; Banaei, Niaz; Dowdy, David W

2014-02-01

Clostridium difficile infection (CDI) is the most common cause of infectious diarrhea in health care settings, and for patients presumed to have CDI, their isolation while awaiting laboratory results is costly. Newer rapid tests for CDI may reduce this burden, but the economic consequences of different testing algorithms remain unexplored. We used decision analysis from the hospital perspective to compare multiple CDI testing algorithms for adult inpatients with suspected CDI, assuming patient management according to laboratory results. CDI testing strategies included combinations of on-demand PCR (odPCR), batch PCR, lateral-flow diagnostics, plate-reader enzyme immunoassay, and direct tissue culture cytotoxicity. In the reference scenario, algorithms incorporating rapid testing were cost-effective relative to nonrapid algorithms. For every 10,000 symptomatic adults, relative to a strategy of treating nobody, lateral-flow glutamate dehydrogenase (GDH)/odPCR generated 831 true-positive results and cost $1,600 per additional true-positive case treated. Stand-alone odPCR was more effective and more expensive, identifying 174 additional true-positive cases at $6,900 per additional case treated. All other testing strategies were dominated by (i.e., more costly and less effective than) stand-alone odPCR or odPCR preceded by lateral-flow screening. A cost-benefit analysis (including estimated costs of missed cases) favored stand-alone odPCR in most settings but favored odPCR preceded by lateral-flow testing if a missed CDI case resulted in less than $5,000 of extended hospital stay costs and <2 transmissions, if lateral-flow GDH diagnostic sensitivity was >93%, or if the symptomatic carrier proportion among the toxigenic culture-positive cases was >80%. These results can aid guideline developers and laboratory directors who are considering rapid testing algorithms for diagnosing CDI.

Economic Evaluation of Laboratory Testing Strategies for Hospital-Associated Clostridium difficile Infection

PubMed Central

Robilotti, Elizabeth; Peterson, Lance R.; Banaei, Niaz; Dowdy, David W.

2014-01-01

Clostridium difficile infection (CDI) is the most common cause of infectious diarrhea in health care settings, and for patients presumed to have CDI, their isolation while awaiting laboratory results is costly. Newer rapid tests for CDI may reduce this burden, but the economic consequences of different testing algorithms remain unexplored. We used decision analysis from the hospital perspective to compare multiple CDI testing algorithms for adult inpatients with suspected CDI, assuming patient management according to laboratory results. CDI testing strategies included combinations of on-demand PCR (odPCR), batch PCR, lateral-flow diagnostics, plate-reader enzyme immunoassay, and direct tissue culture cytotoxicity. In the reference scenario, algorithms incorporating rapid testing were cost-effective relative to nonrapid algorithms. For every 10,000 symptomatic adults, relative to a strategy of treating nobody, lateral-flow glutamate dehydrogenase (GDH)/odPCR generated 831 true-positive results and cost $1,600 per additional true-positive case treated. Stand-alone odPCR was more effective and more expensive, identifying 174 additional true-positive cases at $6,900 per additional case treated. All other testing strategies were dominated by (i.e., more costly and less effective than) stand-alone odPCR or odPCR preceded by lateral-flow screening. A cost-benefit analysis (including estimated costs of missed cases) favored stand-alone odPCR in most settings but favored odPCR preceded by lateral-flow testing if a missed CDI case resulted in less than $5,000 of extended hospital stay costs and <2 transmissions, if lateral-flow GDH diagnostic sensitivity was >93%, or if the symptomatic carrier proportion among the toxigenic culture-positive cases was >80%. These results can aid guideline developers and laboratory directors who are considering rapid testing algorithms for diagnosing CDI. PMID:24478478

Aptamer-phage reporters for ultrasensitive lateral flow assays

PubMed Central

Adhikari, Meena; Strych, Ulrich; Kim, Jinsu; Goux, Heather; Dhamane, Sagar; Poongavanam, Mohan-Vivekanandan; Hagström, Anna E. V.; Kourentzi, Katerina; Conrad, Jacinta C.; Willson, Richard C.

2015-01-01

We introduce the modification of bacteriophage particles with aptamers for the use as bioanalytical reporters, and demonstrate the use of these particles in ultrasensitive lateral flow assays. M13 phage displaying an in vivo biotinylatable peptide (AviTag) genetically fused to the phage tail protein pIII were used as reporter particle scaffolds, with biotinylated aptamers attached via avidin-biotin linkages, and horseradish peroxidase (HRP) reporter enzymes covalently attached to the pVIII coat protein. These modified viral nanoparticles were used in immunochromatographic sandwich assays for the direct detection of IgE and of the penicillin-binding protein from Staphylococcus aureus (PBP2a). We also developed an additional lateral flow assay for IgE, in which the analyte is sandwiched between immobilized anti-IgE antibodies and aptamer-bearing reporter phage modified with HRP. The limit of detection of this LFA was 0.13 ng/mL IgE, ~100 times lower than those of previously reported IgE assays. PMID:26456715

Aptamer-Phage Reporters for Ultrasensitive Lateral Flow Assays.

PubMed

Adhikari, Meena; Strych, Ulrich; Kim, Jinsu; Goux, Heather; Dhamane, Sagar; Poongavanam, Mohan-Vivekanandan; Hagström, Anna E V; Kourentzi, Katerina; Conrad, Jacinta C; Willson, Richard C

2015-12-01

We introduce the modification of bacteriophage particles with aptamers for use as bioanalytical reporters, and demonstrate the use of these particles in ultrasensitive lateral flow assays. M13 phage displaying an in vivo biotinylatable peptide (AviTag) genetically fused to the phage tail protein pIII were used as reporter particle scaffolds, with biotinylated aptamers attached via avidin-biotin linkages, and horseradish peroxidase (HRP) reporter enzymes covalently attached to the pVIII coat protein. These modified viral nanoparticles were used in immunochromatographic sandwich assays for the direct detection of IgE and of the penicillin-binding protein from Staphylococcus aureus (PBP2a). We also developed an additional lateral flow assay for IgE, in which the analyte is sandwiched between immobilized anti-IgE antibodies and aptamer-bearing reporter phage modified with HRP. The limit of detection of this LFA was 0.13 ng/mL IgE, ∼100 times lower than those of previously reported IgE assays.

Designing novel nano-immunoassays: antibody orientation versus sensitivity

NASA Astrophysics Data System (ADS)

Puertas, S.; Moros, M.; Fernández-Pacheco, R.; Ibarra, M. R.; Grazú, V.; de la Fuente, J. M.

2010-12-01

There is a growing interest in the use of magnetic nanoparticles (MNPs) for their application in quantitative and highly sensitive biosensors. Their use as labels of biological recognition events and their detection by means of some magnetic method constitute a very promising strategy for quantitative high-sensitive lateral-flow assays. In this paper, we report the importance of nanoparticle functionalization for the improvement of sensitivity for a lateral-flow immunoassay. More precisely, we have found that immobilization of IgG anti-hCG through its polysaccharide moieties on MNPs allows more successful recognition of the hCG hormone. Although we have used the detection of hCG as a model in this work, the strategy of binding antibodies to MNPs through its sugar chains reported here is applicable to other antibodies. It has huge potential as it will be very useful for the development of quantitative and high-sensitive lateral-flow assays for its use on human and veterinary, medicine, food and beverage manufacturing, pharmaceutical, medical biologics and personal care product production, environmental remediation, etc.

A CCD-based reader combined with CdS quantum dot-labeled lateral flow strips for ultrasensitive quantitative detection of CagA

NASA Astrophysics Data System (ADS)

Gui, Chen; Wang, Kan; Li, Chao; Dai, Xuan; Cui, Daxiang

2014-02-01

Immunochromatographic assays are widely used to detect many analytes. CagA is proved to be associated closely with initiation of gastric carcinoma. Here, we reported that a charge-coupled device (CCD)-based test strip reader combined with CdS quantum dot-labeled lateral flow strips for quantitative detection of CagA was developed, which used 365-nm ultraviolet LED as the excitation light source, and captured the test strip images through an acquisition module. Then, the captured image was transferred to the computer and was processed by a software system. A revised weighted threshold histogram equalization (WTHE) image processing algorithm was applied to analyze the result. CdS quantum dot-labeled lateral flow strips for detection of CagA were prepared. One hundred sera samples from clinical patients with gastric cancer and healthy people were prepared for detection, which demonstrated that the device could realize rapid, stable, and point-of-care detection, with a sensitivity of 20 pg/mL.

Heat Transfer to Anode of Arc as Function of Transverse Magnetic Field and Lateral Gas Flow Velocity

NASA Astrophysics Data System (ADS)

Zama, Yoshiyuki; Shiino, Toru; Ishii, Yoko; Maeda, Yoshifumi; Yamamoto, Shinji; Iwao, Toru

2016-10-01

Gas tungsten arc welding has useful joining technology because of high-energy and high-current characteristics. It can be flexible from the transverse magnetic field and lateral gas flow velocity. In this case, the weld defect occurs. In this research, the heat transfer to the anode of the arc as a function of the transverse magnetic field and lateral gas flow velocity is elucidated. That magnetic flux density and lateral gas velocity were varied from 0 to 3 mT and 0 to 50?m?s -1, respectively. The axial plasma gas argon flow rates were 3?slm. A transverse magnetic field is applied to the arc using Helmholtz coil. The anode is used by a water-cooled copper plate, and the heat transfer is measured by temperature of cooled water. As a result, the arc is deflected by the Lorentz force and lateral gas convection. Thus, the heat transfer to the anode of the arc decreases with increasing the transverse magnetic field and lateral gas flow velocity. In addition, the heat transfer to the anode changes with different attachments modes. The lateral gas flow causes a convective heat loss from the arc to the chamber walls.

Direction of unsaturated flow in a homogeneous and isotropic hillslope

USGS Publications Warehouse

Lu, Ning; Kaya, Basak Sener; Godt, Jonathan W.

2011-01-01

The distribution of soil moisture in a homogeneous and isotropic hillslope is a transient, variably saturated physical process controlled by rainfall characteristics, hillslope geometry, and the hydrological properties of the hillslope materials. The major driving mechanisms for moisture movement are gravity and gradients in matric potential. The latter is solely controlled by gradients of moisture content. In a homogeneous and isotropic saturated hillslope, absent a gradient in moisture content and under the driving force of gravity with a constant pressure boundary at the slope surface, flow is always in the lateral downslope direction, under either transient or steady state conditions. However, under variably saturated conditions, both gravity and moisture content gradients drive fluid motion, leading to complex flow patterns. In general, the flow field near the ground surface is variably saturated and transient, and the direction of flow could be laterally downslope, laterally upslope, or vertically downward. Previous work has suggested that prevailing rainfall conditions are sufficient to completely control these flow regimes. This work, however, shows that under time-varying rainfall conditions, vertical, downslope, and upslope lateral flow can concurrently occur at different depths and locations within the hillslope. More importantly, we show that the state of wetting or drying in a hillslope defines the temporal and spatial regimes of flow and when and where laterally downslope and/or laterally upslope flow occurs.

Direction of unsaturated flow in a homogeneous and isotropic hillslope

USGS Publications Warehouse

Lu, N.; Kaya, B.S.; Godt, J.W.

2011-01-01

The distribution of soil moisture in a homogeneous and isotropic hillslope is a transient, variably saturated physical process controlled by rainfall characteristics, hillslope geometry, and the hydrological properties of the hillslope materials. The major driving mechanisms for moisture movement are gravity and gradients in matric potential. The latter is solely controlled by gradients of moisture content. In a homogeneous and isotropic saturated hillslope, absent a gradient in moisture content and under the driving force of gravity with a constant pressure boundary at the slope surface, flow is always in the lateral downslope direction, under either transient or steady state conditions. However, under variably saturated conditions, both gravity and moisture content gradients drive fluid motion, leading to complex flow patterns. In general, the flow field near the ground surface is variably saturated and transient, and the direction of flow could be laterally downslope, laterally upslope, or vertically downward. Previous work has suggested that prevailing rainfall conditions are sufficient to completely control these flow regimes. This work, however, shows that under time-varying rainfall conditions, vertical, downslope, and upslope lateral flow can concurrently occur at different depths and locations within the hillslope. More importantly, we show that the state of wetting or drying in a hillslope defines the temporal and spatial regimes of flow and when and where laterally downslope and/or laterally upslope flow occurs. Copyright 2011 by the American Geophysical Union.

Spot test kit for explosives detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pagoria, Philip F; Whipple, Richard E; Nunes, Peter J

An explosion tester system comprising a body, a lateral flow membrane swab unit adapted to be removeably connected to the body, a first explosives detecting reagent, a first reagent holder and dispenser operatively connected to the body, the first reagent holder and dispenser containing the first explosives detecting reagent and positioned to deliver the first explosives detecting reagent to the lateral flow membrane swab unit when the lateral flow membrane swab unit is connected to the body, a second explosives detecting reagent, and a second reagent holder and dispenser operatively connected to the body, the second reagent holder and dispensermore » containing the second explosives detecting reagent and positioned to deliver the second explosives detecting reagent to the lateral flow membrane swab unit when the lateral flow membrane swab unit is connected to the body.« less

Development of a cerebrospinal fluid lateral reservoir model in rhesus monkeys (Macaca mulatta).

PubMed

Lester McCully, Cynthia M; Bacher, John; MacAllister, Rhonda P; Steffen-Smith, Emilie A; Saleem, Kadharbatcha; Thomas, Marvin L; Cruz, Rafael; Warren, Katherine E

2015-02-01

Rapid, serial, and humane collection of cerebrospinal fluid (CSF) in nonhuman primates (NHP) is an essential element of numerous research studies and is currently accomplished via two different models. The CSF reservoir model (FR) combines a catheter in the 4th ventricle with a flexible silastic reservoir to permit circulating CSF flow. The CSF lateral port model (LP) consists of a lateral ventricular catheter and an IV port that provides static access to CSF and volume restrictions on sample collection. The FR model is associated with an intensive, prolonged recovery and frequent postsurgical hydrocephalus and nonpatency, whereas the LP model is associated with an easier recovery. To maximize the advantages of both systems, we developed the CSF lateral reservoir model (LR), which combines the beneficial features of the 2 previous models but avoids their limitations by using a reservoir for circulating CSF flow combined with catheter placement in the lateral ventricle. Nine adult male rhesus monkeys were utilized in this study. Pre-surgical MRI was performed to determine the coordinates of the lateral ventricle and location of choroid plexus (CP). The coordinates were determined to avoid the CP and major blood vessels. The predetermined coordinates were 100% accurate, according to MRI validation. The LR system functioned successfully in 67% of cases for 221 d, and 44% remain functional at 426 to 510 d postoperatively. Compared with established models, our LR model markedly reduced postoperative complications and recovery time. Development of the LR model was successful in rhesus macaques and is a useful alternative to the FR and LP methods of CSF collection from nonhuman primates.

Development of Lateral Flow Immunochromatographic Strips for Micropollutants Screening Using Colorants of Aptamer Functionalized Nanogold Particles Part I: Methodology and Optimization.

PubMed

Zhao, Shuai; Zhang, Shan; Wang, Sai; Liu, Jiahui; Dong, Yiyang

2018-05-03

A methodology of lateral flow immunochromatographic strip based on aptamer was developed for on-site detectionof the small molecule micropollutants. In the present study, we try for the first time to investigate the feasibility of developing a strip assay for the analysis of micropollutants as methodological prototypes by combining the high selectivity and affinity of aptamers with the unique optical properties of nanogolds. This quantitative method was based on the competition for the aptamer between targets and DNA probes. Crucial parameters that might influence the sensitivity, such as the size of nanogolds, amount of aptamer, type and pH of streptavidin, type of nitrocellulose (NC) membrane, blocking procedure, and reading time, were systematically investigated to obtain the optimum assay performance. With the optimized conditions [nanogolds 25 nm, 50 μM aptamer, pH 8 of GSA (a type of streptavidin named "SA Gold," which is a sulfhydrylization streptavidin), Millipore HFC 135 NC membrane, 1% bovine serum albumin as the blocking agent and added in the running buffer and sample pad soakage agents, and 20 min reading time] the aptamer-based lateral flow assay will show a low visual limit of detection and scanning reader LOD. The strip for on-site screening using colorants of aptamer functionalized nanogold particles did not require any complicated equipment and was a potential portable tool for rapid identification of micropollutants.

Evaluation of a new nanoparticle-based lateral-flow immunoassay for the exclusion of heparin-induced thrombocytopenia (HIT).

PubMed

Sachs, Ulrich J; von Hesberg, Jakob; Santoso, Sentot; Bein, Gregor; Bakchoul, Tamam

2011-12-01

Heparin-induced thrombocytopenia (HIT) is an adverse complication of heparin caused by HIT antibodies (abs) that recognise platelet factor 4-heparin (PF4/hep) complexes. Several laboratory tests are available for the confirmation and/or refutation of HIT. A reliable and rapid single-sample test is still pending. It was the objective of this study to evaluate a new lateral-flow immunoassay based on nanoparticle technology. A cohort of 452 surgical and medical patients suspected of having HIT was evaluated. All samples were tested in two IgG-specific ELISAs, in a particle gel immunoassay (PaGIA) and in a newly developed lateral-flow immunoassay (LFI-HIT) as well as in a functional test (HIPA). Clinical pre-test probability was determined using 4T's score. Platelet-activating antibodies were present in 34/452 patients, all of whom had intermediate to high clinical probability. PF4/hep abs were detected in 79, 87, 86, and 63 sera using the four different immunoassays. The negative predictive values (NPV) were 100% for both ELISA tests and LFI-HIT but only 99.2% for PaGIA. There were less false positives (n=29) in the LFI-HIT compared to any other test. Additionally, significantly less time was required to perform LFI-HIT than to perform the other immunoassays. In conclusion, a newly developed lateral-flow assay, LFI-HIT, was capable of identifying all HIT patients in a cohort in a short period of time. Beside an NPV of 100%, the rate of false-positive signals is significantly lower with LFI-HIT than with other immunoassay(s). These performance characteristics suggest a high potency in reducing the risk and costs in patients suspected of having HIT.

CdSe/ZnS Quantum Dot-Labeled Lateral Flow Strips for Rapid and Quantitative Detection of Gastric Cancer Carbohydrate Antigen 72-4

NASA Astrophysics Data System (ADS)

Yan, Xinyu; Wang, Kan; Lu, Wenting; Qin, Weijian; Cui, Daxiang; He, Jinghua

2016-03-01

Carbohydrate antigen 72-4 (CA72-4) is an important biomarker associated closely with diagnosis and prognosis of early gastric cancer. How to realize quick, sensitive, specific, and quantitative detection of CA72-4 in clinical specimens has become a great requirement. Herein, we reported a CdSe/ZnS quantum dot-labeled lateral flow test strip combined with a charge-coupled device (CCD)-based reader was developed for rapid, sensitive, and quantitative detection of CA72-4. Two mouse monoclonal antibodies (mAbs) against CA72-4 were employed. One of them was coated as a test line, while another mAb was labeled with quantum dots and coated onto conjugate pad. The goat anti-mouse IgG was immobilized as a control line. After sample was added, a sandwich structure was formed with CA72-4 and these two mAbs. The fluorescent signal from quantum dots (QD)-labeled mAb in sandwich structure was related to the amount of detected CA72-4. A CCD-based reader was used to realize quantitative detection of CA72-4. Results showed that developed QD-labeled lateral flow strips to detect CA72-4 biomarker with the sensitivity of 2 IU/mL and 10 min detection time. One hundred sera samples from clinical patients with gastric cancer and healthy people were used to confirm specificity of this strip method; results showed that established strip method own 100 % reproducibility and 100 % specificity compared with Roche electrochemiluminescence assay results. In conclusion, CdSe/ZnS quantum dot-labeled lateral flow strips for detection of CA72-4 could realize rapid, sensitive, and specific detection of clinical samples and could own great potential in clinical translation in near future.

A fluorometric lateral flow assay for visual detection of nucleic acids using a digital camera readout.

PubMed

Magiati, Maria; Sevastou, Areti; Kalogianni, Despina P

2018-06-04

A fluorometric lateral flow assay has been developed for the detection of nucleic acids. The fluorophores phycoerythrin (PE) and fluorescein isothiocyanate (FITC) were used as labels, while a common digital camera and a colored vinyl-sheet, acting as a cut-off optical filter, are used for fluorescence imaging. After DNA amplification by polymerase chain reaction (PCR), the biotinylated PCR product is hybridized to its complementary probe that carries a poly(dA) tail at 3΄ edge and then applied to the lateral flow strip. The hybrids are captured to the test zone of the strip by immobilized poly(dT) sequences and detected by streptavidin-fluorescein and streptavidin-phycoerythrin conjugates, through streptavidin-biotin interaction. The assay is widely applicable, simple, cost-effective, and offers a large multiplexing potential. Its performance is comparable to assays based on the use of streptavidin-gold nanoparticles conjugates. As low as 7.8 fmol of a ssDNA and 12.5 fmol of an amplified dsDNA target were detectable. Graphical abstract Schematic presentation of a fluorometric lateral flow assay based on fluorescein and phycoerythrin fluorescent labels for the detection of single-stranded (ssDNA) and double-stranded DNA (dsDNA) sequences and using a digital camera readout. SA: streptavidin, BSA: Bovine Serum Albumin, B: biotin, FITC: fluorescein isothiocyanate, PE: phycoerythrin, TZ: test zone, CZ: control zone.

Contribution of lateral terrestrial water flows to the regional hydrological cycle: A joint soil-atmospheric moisture tagging procedure with WRF-Hydro

NASA Astrophysics Data System (ADS)

Arnault, Joel; Wei, Jianhui; Zhang, Zhenyu; Wagner, Sven; Kunstmann, Harald

2017-04-01

Water resources management requires an accurate knowledge of the behavior of the regional hydrological cycle components, including precipitation, evapotranspiration, river discharge and soil water storage. Atmospheric models such as the Weather Research and Forecasting (WRF) model provide a tool to evaluate these components. The main drawback of these atmospheric models, however, is that the terrestrial segment of the hydrological cycle is reduced to vertical infiltration, and that lateral terrestrial water flows are neglected. Recent model developments have focused on coupled atmospheric-hydrological modeling systems, such as WRF-hydro, in order to take into account subsurface, overland and river flow. The aim of this study is to investigate the contribution of lateral terrestrial water flows to the regional hydrological cycle, with the help of a joint soil-atmospheric moisture tagging procedure. This procedure is the extended version of an existing atmospheric moisture tagging method developed in WRF and WRF-Hydro (Arnault et al. 2017). It is used to quantify the partitioning of precipitation into water stored in the soil, runoff, evapotranspiration, and potentially subsequent precipitation through regional recycling. An application to a high precipitation event on 23 June 2009 in the upper Danube river basin, Germany and Austria, is presented. Precipitating water during this day is tagged for the period 2009-2011. Its contribution to runoff and evapotranspiration decreases with time, but is still not negligible in the summer 2011. At the end of the study period, less than 5 % of the precipitating water on 23 June 2009 remains in the soil. The additionally resolved lateral terrestrial water flows in WRF-Hydro modify the partitioning between surface and underground runoff, in association with a slight increase of evapotranspiration and recycled precipitation. Reference: Arnault, J., R. Knoche, J. Wei, and H. Kunstmann (2016), Evaporation tagging and atmospheric water budget analysis with WRF: A regional precipitation recycling study for West Africa, Water Resour. Res., 52, 1544-1567, doi:10.1002/2015WR017704.

Colorimetric chemical analysis sampler for the presence of explosives

DOEpatents

Nunes, Peter J [Danville, CA; Del Eckels, Joel [Livermore, CA; Reynolds, John G [San Ramon, CA; Pagoria, Philip F [Livermore, CA; Simpson, Randall L [Livermore, CA

2011-09-27

A tester for testing for explosives comprising a body, a lateral flow swab unit operably connected to the body, a explosives detecting reagent contained in the body, and a dispenser operatively connected to the body and the lateral flow swab unit. The dispenser selectively allows the explosives detecting reagent to be delivered to the lateral flow swab unit.

Colorimetric chemical analysis sampler for the presence of explosives

DOEpatents

Nunes, Peter J.; Eckels, Joel Del; Reynolds, John G.; Pagoria, Philip F.; Simpson, Randall L.

2014-07-01

A tester for testing for explosives comprising a body, a lateral flow swab unit operably connected to the body, a explosives detecting reagent contained in the body, and a dispenser operatively connected to the body and the lateral flow swab unit. The dispenser selectively allows the explosives detecting reagent to be delivered to the lateral flow swab unit.

α-, β-phenomena in the post-symmetry break for the flow past a circular cylinder

NASA Astrophysics Data System (ADS)

Kalita, Jiten C.; Sen, Shuvam

2017-03-01

In the existing literature, the so-called α- and β-phenomena have been reported only for the early stages for the flow past an impulsively started circular cylinder. The current study endeavours to explore the possible existence of these phenomena even in the later stages of the flow. The flow is computed using a recently developed compact finite difference method for the biharmonic form of the two-dimensional Navier-Stokes equations for a wide range of Reynolds numbers (Re). We establish that these secondary phenomena not only appear once the wake becomes asymmetric but also periodically during the post-vortex shedding period for Re = 1000. Further, the recently reported sub-α- and sub-β-phenomena for Re = 5000 at the tertiary level during the early stages of the flow could be identified even during the later stages of the flow as well. The formation of these tertiary structures has been explained through a detailed theoretical characterization of the topological aspects of the boundary layer separation. Both qualitative and quantitative results are provided to substantiate our claim.

Microfluidic paper-based biomolecule preconcentrator based on ion concentration polarization.

PubMed

Han, Sung Il; Hwang, Kyo Seon; Kwak, Rhokyun; Lee, Jeong Hoon

2016-06-21

Microfluidic paper-based analytical devices (μPADs) for molecular detection have great potential in the field of point-of-care diagnostics. Currently, a critical problem being faced by μPADs is improving their detection sensitivity. Various preconcentration processes have been developed, but they still have complicated structures and fabrication processes to integrate into μPADs. To address this issue, we have developed a novel paper-based preconcentrator utilizing ion concentration polarization (ICP) with minimal addition on lateral-flow paper. The cation selective membrane (i.e., Nafion) is patterned on adhesive tape, and this tape is then attached to paper-based channels. When an electric field is applied across the Nafion, ICP is initiated to preconcentrate the biomolecules in the paper channel. Departing from previous paper-based preconcentrators, we maintain steady lateral fluid flow with the separated Nafion layer; as a result, fluorescent dyes and proteins (FITC-albumin and bovine serum albumin) are continuously delivered to the preconcentration zone, achieving high preconcentration performance up to 1000-fold. In addition, we demonstrate that the Nafion-patterned tape can be integrated with various geometries (multiplexed preconcentrator) and platforms (string and polymer microfluidic channel). This work would facilitate integration of various ICP devices, including preconcentrators, pH/concentration modulators, and micro mixers, with steady lateral flows in paper-based platforms.

Smartphone-Based Dual-Modality Imaging System for Quantitative Detection of Color or Fluorescent Lateral Flow Immunochromatographic Strips

NASA Astrophysics Data System (ADS)

Hou, Yafei; Wang, Kan; Xiao, Kun; Qin, Weijian; Lu, Wenting; Tao, Wei; Cui, Daxiang

2017-04-01

Nowadays, lateral flow immunochromatographic assays are increasingly popular as a diagnostic tool for point-of-care (POC) test based on their simplicity, specificity, and sensitivity. Hence, quantitative detection and pluralistic popular application are urgently needed in medical examination. In this study, a smartphone-based dual-modality imaging system was developed for quantitative detection of color or fluorescent lateral flow test strips, which can be operated anywhere at any time. In this system, the white and ultra-violet (UV) light of optical device was designed, which was tunable with different strips, and the Sobel operator algorithm was used in the software, which could enhance the identification ability to recognize the test area from the background boundary information. Moreover, this technology based on extraction of the components from RGB format (red, green, and blue) of color strips or only red format of the fluorescent strips can obviously improve the high-signal intensity and sensitivity. Fifty samples were used to evaluate the accuracy of this system, and the ideal detection limit was calculated separately from detection of human chorionic gonadotropin (HCG) and carcinoembryonic antigen (CEA). The results indicated that smartphone-controlled dual-modality imaging system could provide various POC diagnoses, which becomes a potential technology for developing the next-generation of portable system in the near future.

Multiplexed Lateral Flow Test for Detection and Differentiation of Cronobacter sakazakii Serotypes O1 and O2

PubMed Central

Scharinger, Eva J.; Dietrich, Richard; Wittwer, Tobias; Märtlbauer, Erwin; Schauer, Kristina

2017-01-01

The ubiquitous and opportunistic pathogen Cronobacter sakazakii is responsible for severe meningitis, sepsis, and necrotizing enterocolitis in neonates and infants associated with ingestion of contaminated powdered infant formula (PIF). The current ISO method for isolation and detection of Cronobacter spp. is laborious, time-consuming and expensive. In this study, a multiplexed lateral flow test strip was developed to rapidly detect and simultaneously serotype O1 and O2 C. sakazakii serotypes. The assay is based on two monoclonal antibodies (MAb) that specifically bind to the lipopolysaccharides (LPS) of these pathogens. The test strip provides results very quickly; C. sakazakii could be detected in pure culture within 15 min with a sensitivity of 107 CFU/ml. After non-selective enrichment for 18 h as low as one Cronobacter cell per g PIF could be detected. Moreover, the established lateral flow assay (LFA) offers excellent specificity showing no cross-reactivity with other C. sakazakii serotypes, Cronobacter species or Enterobacteriaceae tested. These characteristics, together with several advantages such as speed, simplicity in performance, low analysis cost, and no requirement of specialized skills or sophisticated equipment make the developed multiplexed LFA suitable for reliable detection and serotyping of C. sakazakii serotypes O1 and O2. PMID:28979257

Multiplexed Lateral Flow Test for Detection and Differentiation of Cronobacter sakazakii Serotypes O1 and O2.

PubMed

Scharinger, Eva J; Dietrich, Richard; Wittwer, Tobias; Märtlbauer, Erwin; Schauer, Kristina

2017-01-01

The ubiquitous and opportunistic pathogen Cronobacter sakazakii is responsible for severe meningitis, sepsis, and necrotizing enterocolitis in neonates and infants associated with ingestion of contaminated powdered infant formula (PIF). The current ISO method for isolation and detection of Cronobacter spp. is laborious, time-consuming and expensive. In this study, a multiplexed lateral flow test strip was developed to rapidly detect and simultaneously serotype O1 and O2 C. sakazakii serotypes. The assay is based on two monoclonal antibodies (MAb) that specifically bind to the lipopolysaccharides (LPS) of these pathogens. The test strip provides results very quickly; C. sakazakii could be detected in pure culture within 15 min with a sensitivity of 10 7 CFU/ml. After non-selective enrichment for 18 h as low as one Cronobacter cell per g PIF could be detected. Moreover, the established lateral flow assay (LFA) offers excellent specificity showing no cross-reactivity with other C. sakazakii serotypes, Cronobacter species or Enterobacteriaceae tested. These characteristics, together with several advantages such as speed, simplicity in performance, low analysis cost, and no requirement of specialized skills or sophisticated equipment make the developed multiplexed LFA suitable for reliable detection and serotyping of C. sakazakii serotypes O1 and O2.

Gold nanoparticle based Tuberculosis immunochromatographic assay: the quantitative ESE Quanti analysis of the intensity of test and control lines.

PubMed

Mdluli, Phumlani; Tetyana, Phumlani; Sosibo, Ndabenhle; van der Walt, Hendriëtte; Mlambo, Mbuso; Skepu, Amanda; Tshikhudo, Robert

2014-04-15

A rapid dual channel lateral flow assay for the detection of Mycobacterium Tuberculosis antibodies (MTB 38 kDa monoclonal antibody) in human blood was developed. The MTB 6-14-38 kDa fusion antigen and anti-Protein A were used as the capture proteins for test and control lines respectively. Protein A labeled 40 nm gold nanoparticles were used as the detection conjugate. Whole blood and serum were spiked with MTB 38 kDa monoclonal antibody to make a positive sample model. The developed lateral flow was used to test MTB 38 kDa monoclonal antibody, and a detection limit of 5 ng/ml was used as a cut-off concentration of the analytes. The effect of the analyte concentration on the MTB lateral flow assay was studied using the variation of the intensity obtained from a ESE Quanti reader. There was a direct correlation between the analyte (MTB 38 kDa monoclonal antibody) concentration and the intensity of the test line. The intensity increased with an increase in the concentration of MTB 38 kDa monoclonal antibody, while in contrast, an increase in analyte concentration decreased the intensity of the control line. © 2013 Published by Elsevier B.V.

49 CFR 262.7 - Eligibility.

Code of Federal Regulations, 2012 CFR

2012-10-01

... out for the purpose of mitigating the adverse effects of rail traffic on safety, motor vehicle traffic flow, community quality of life, or economic development; or (2) Involves a lateral or vertical...

49 CFR 262.7 - Eligibility.

Code of Federal Regulations, 2014 CFR

2014-10-01

... out for the purpose of mitigating the adverse effects of rail traffic on safety, motor vehicle traffic flow, community quality of life, or economic development; or (2) Involves a lateral or vertical...

49 CFR 262.7 - Eligibility.

Code of Federal Regulations, 2011 CFR

2011-10-01

... out for the purpose of mitigating the adverse effects of rail traffic on safety, motor vehicle traffic flow, community quality of life, or economic development; or (2) Involves a lateral or vertical...

49 CFR 262.7 - Eligibility.

Code of Federal Regulations, 2013 CFR

2013-10-01

... out for the purpose of mitigating the adverse effects of rail traffic on safety, motor vehicle traffic flow, community quality of life, or economic development; or (2) Involves a lateral or vertical...

Wave propagation and power flow in an acoustic metamaterial plate with lateral local resonance attachment

NASA Astrophysics Data System (ADS)

Wang, Ting; Sheng, Meiping; Ding, Xiaodong; Yan, Xiaowei

2018-03-01

This paper presents analysis on wave propagation and power flow in an acoustic metamaterial plate with lateral local resonance. The metamaterial is designed to have lateral local resonance systems attached to a homogeneous plate. Relevant theoretical analysis, numerical modelling and application prospect are presented. Results show that the metamaterial has two complete band gaps for flexural wave absorption and vibration attenuation. Damping can smooth and lower the metamaterial’s frequency responses in high frequency ranges at the expense of the band gap effect, and as an important factor to calculate the power flow is thoroughly investigated. Moreover, the effective mass density becomes negative and unbounded at specific frequencies. Simultaneously, power flow within band gaps are dramatically blocked from the power flow contour and power flow maps. Results from finite element modelling and power flow analysis reveal the working mechanism of the flexural wave attenuation and power flow blocked within the band gaps, where part of the flexural vibration is absorbed by the vertical resonator and the rest is transformed through four-link-mechanisms to the lateral resonators that oscillate and generate inertial forces indirectly to counterbalance the shear forces induced by the vibrational plate. The power flow is stored in the vertical and lateral local resonance, as well as in the connected plate.

Investigation of particle lateral migration in sample-sheath flow of viscoelastic fluid and Newtonian fluid.

PubMed

Yuan, Dan; Zhang, Jun; Yan, Sheng; Peng, Gangrou; Zhao, Qianbin; Alici, Gursel; Du, Hejun; Li, Weihua

2016-08-01

In this work, particle lateral migration in sample-sheath flow of viscoelastic fluid and Newtonian fluid was experimentally investigated. The 4.8-μm micro-particles were dispersed in a polyethylene oxide (PEO) viscoelastic solution, and then the solution was injected into a straight rectangular channel with a deionised (DI) water Newtonian sheath flow. Micro-particles suspended in PEO solution migrated laterally to a DI water stream, but migration in the opposite direction from a DI water stream to a PEO solution stream or from one DI water stream to another DI water stream could not be achieved. The lateral migration of particles depends on the viscoelastic properties of the sample fluids. Furthermore, the effects of channel length, flow rate, and PEO concentration were studied. By using viscoelastic sample flow and Newtonian sheath flow, a selective particle lateral migration can be achieved in a simple straight channel, without any external force fields. This particle lateral migration technique could be potentially used in solution exchange fields such as automated cell staining and washing in microfluidic platforms, and holds numerous biomedical applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Model to Design Drip Hose Lateral Line

NASA Astrophysics Data System (ADS)

Ludwig, Rafael; Cury Saad, João Carlos

2014-05-01

Introduction The design criterion for non-pressure compensating drip hose is normally to have 10% of flow variation (Δq) in the lateral line, corresponding to 20% of head pressure variation (ΔH). Longer lateral lines in drip irrigation systems using conventional drippers provide cost reduction, but it is necessary to obtain to the uniformity of irrigation [1]. The use of Δq higher levels can provide longer lateral lines. [4] proposes the use of a 30% Δq and he found that this value resulted in distribution uniformity over 80%. [1] considered it is possible to extend the lateral line length using two emitters spacing in different section. He assumed that the spacing changing point would be at 40% of the total length, because this is approximately the location of the average flow according with [2]. [3] found that, for practical purposes, the average pressure is located at 40% of the length of the lateral line and that until this point it has already consumed 75% of total pressure head loss (hf ). In this case, the challenge for designers is getting longer lateral lines with high values of uniformity. Objective The objective of this study was to develop a model to design longer lateral lines using non-pressure compensating drip hose. Using the developed model, the hypotheses to be evaluated were: a) the use of two different spacing between emitters in the same lateral line allows longer length; b) it is possible to get longer lateral lines using high values of pressure variation in the lateral lines since the distribution uniformity stays below allowable limits. Methodology A computer program was developed in Delphi® based on the model developed and it is able to design lateral lines in level using non-pressure compensating drip hose. The input data are: desired distribution uniformity (DU); initial and final pressure in the lateral line; coefficients of relationship between emitter discharge and pressure head; hose internal diameter; pipe cross-sectional area with the dripper; and roughness coefficient for the Hazen-Williams equation. The program allows calculate the lateral line length with three possibilities: selecting two spacing between emitters and defining the exchange point; using two pre-established spacing between emitters and calculating the length of each section with different spacing; using one emitter spacing. Results Results showed that the use of two sections with different spacing between drippers in the lateral line didn't allow longer length but got better uniformity when compared with lateral line with one spacing between emitters. The adoption of two spacing increased the flow rate per meter in the final section which represented approximately 80% of the lateral line total length and this justifies their use. The software allowed DU above 90% with pressure head variation of 40% and the use of two spacing between emitters. Conclusions The developed model/software showed to be accurate, easy to handle and useful for lateral line design using non-pressure compensating drip hose. References [1] ANDRADE, L. A. D. Estudo de uniformidade de emissão de água utilizando diferentes espaçamentos entre gotejadores na linha lateral. 2009. 87 f. Tese (Doutorado em Agronomia/Irigação e Drenagem) - Faculdade de Ciências Agronômicas, Universidade Estadual Paulista 'Julio de Mesquita Filho', Botucatu, (2009). [2] KELLER, J.; BLIESNER, R. D. Sprinkle and trickle irrigation. Caldwell: Blackburn Press, (1990). 652 p. [3] TALENS, J. A. M. Riego localizado y fertirrigacion. Madrid: Mundi-Prensa, (2002). 533 p. [4] WU, I. P. An assessment of hydraulic design of micro-irrigation systems. Agricultural Water Management, Amsterdan, v. 32, n. 3

Imaging dipole flow sources using an artificial lateral-line system made of biomimetic hair flow sensors

PubMed Central

Dagamseh, Ahmad; Wiegerink, Remco; Lammerink, Theo; Krijnen, Gijs

2013-01-01

In Nature, fish have the ability to localize prey, school, navigate, etc., using the lateral-line organ. Artificial hair flow sensors arranged in a linear array shape (inspired by the lateral-line system (LSS) in fish) have been applied to measure airflow patterns at the sensor positions. Here, we take advantage of both biomimetic artificial hair-based flow sensors arranged as LSS and beamforming techniques to demonstrate dipole-source localization in air. Modelling and measurement results show the artificial lateral-line ability to image the position of dipole sources accurately with estimation error of less than 0.14 times the array length. This opens up possibilities for flow-based, near-field environment mapping that can be beneficial to, for example, biologists and robot guidance applications. PMID:23594816

Measuring flow velocity and flow direction by spatial and temporal analysis of flow fluctuations.

PubMed

Chagnaud, Boris P; Brücker, Christoph; Hofmann, Michael H; Bleckmann, Horst

2008-04-23

If exposed to bulk water flow, fish lateral line afferents respond only to flow fluctuations (AC) and not to the steady (DC) component of the flow. Consequently, a single lateral line afferent can encode neither bulk flow direction nor velocity. It is possible, however, for a fish to obtain bulk flow information using multiple afferents that respond only to flow fluctuations. We show by means of particle image velocimetry that, if a flow contains fluctuations, these fluctuations propagate with the flow. A cross-correlation of water motion measured at an upstream point with that at a downstream point can then provide information about flow velocity and flow direction. In this study, we recorded from pairs of primary lateral line afferents while a fish was exposed to either bulk water flow, or to the water motion caused by a moving object. We confirm that lateral line afferents responded to the flow fluctuations and not to the DC component of the flow, and that responses of many fiber pairs were highly correlated, if they were time-shifted to correct for gross flow velocity and gross flow direction. To prove that a cross-correlation mechanism can be used to retrieve the information about gross flow velocity and direction, we measured the flow-induced bending motions of two flexible micropillars separated in a downstream direction. A cross-correlation of the bending motions of these micropillars did indeed produce an accurate estimate of the velocity vector along the direction of the micropillars.

An evaluation of the hydrologic relevance of lateral flow in snow at hillslope and catchment scales

Treesearch

David Eiriksson; Michael Whitson; Charles H. Luce; Hans Peter Marshall; John Bradford; Shawn G. Benner; Thomas Black; Hank Hetrick; James P. McNamara

2013-01-01

Lateral downslope flow in snow during snowmelt and rain-on-snow (ROS) events is a well-known phenomenon, yet its relevance to water redistribution at hillslope and catchment scales is not well understood. We used dye tracers, geophysical methods, and hydrometric measurements to describe the snow properties that promote lateral flow, assess the relative velocities of...

Lateral weathering gradients in glaciated catchments

NASA Astrophysics Data System (ADS)

McGuire, K. J.; Bailey, S. W.; Ross, D. S.; Strahm, B. D.; Schreiber, M. E.

2016-12-01

Mineral dissolution and the distribution of weathering products are fundamental processes that drive development and habitability of the Earth's critical zone; yet, the spatial configuration of these processes in some systems is not well understood. Feedbacks between hydrologic flows and weathering fluxes are necessary to understanding how the critical zone develops. In upland glaciated catchments of the northeastern USA, primary mineral dissolution and the distribution of weathering products are spatially distinct and predictable over short distances. Hillslopes, where shallow soils force lateral hydrologic fluxes through accumulated organic matter, produce downslope gradients in mineral depletion, weathering product accumulation, soil development, and solute chemistry. We propose that linked gradients in hydrologic flow paths, soil depth, and vegetation lead to predictable differences in the location and extent of mineral dissolution in regolith (soil, subsoil, and rock fragments) and bedrock, and that headwater catchments within the upland glaciated northeast show a common architecture across hillslopes as a result. Examples of these patterns and processes will be illustrated using observations from the Hubbard Brook Experimental Forest in New Hampshire where laterally distinct soils with strong morphological and biogeochemical gradients have been documented. Patterns in mineral depletion and product accumulation are essential in predicting how ecosystems will respond to stresses, disturbance, and management.

Distributed flow estimation and closed-loop control of an underwater vehicle with a multi-modal artificial lateral line.

PubMed

DeVries, Levi; Lagor, Francis D; Lei, Hong; Tan, Xiaobo; Paley, Derek A

2015-03-25

Bio-inspired sensing modalities enhance the ability of autonomous vehicles to characterize and respond to their environment. This paper concerns the lateral line of cartilaginous and bony fish, which is sensitive to fluid motion and allows fish to sense oncoming flow and the presence of walls or obstacles. The lateral line consists of two types of sensing modalities: canal neuromasts measure approximate pressure gradients, whereas superficial neuromasts measure local flow velocities. By employing an artificial lateral line, the performance of underwater sensing and navigation strategies is improved in dark, cluttered, or murky environments where traditional sensing modalities may be hindered. This paper presents estimation and control strategies enabling an airfoil-shaped unmanned underwater vehicle to assimilate measurements from a bio-inspired, multi-modal artificial lateral line and estimate flow properties for feedback control. We utilize potential flow theory to model the fluid flow past a foil in a uniform flow and in the presence of an upstream obstacle. We derive theoretically justified nonlinear estimation strategies to estimate the free stream flowspeed, angle of attack, and the relative position of an upstream obstacle. The feedback control strategy uses the estimated flow properties to execute bio-inspired behaviors including rheotaxis (the tendency of fish to orient upstream) and station-holding (the tendency of fish to position behind an upstream obstacle). A robotic prototype outfitted with a multi-modal artificial lateral line composed of ionic polymer metal composite and embedded pressure sensors experimentally demonstrates the distributed flow sensing and closed-loop control strategies.

Instrumental record of debris flow initiation during natural rainfall: Implications for modeling slope stability

USGS Publications Warehouse

Montgomery, D.R.; Schmidt, K.M.; Dietrich, W.E.; McKean, J.

2009-01-01

The middle of a hillslope hollow in the Oregon Coast Range failed and mobilized as a debris flow during heavy rainfall in November 1996. Automated pressure transducers recorded high spatial variability of pore water pressure within the area that mobilized as a debris flow, which initiated where local upward flow from bedrock developed into overlying colluvium. Postfailure observations of the bedrock surface exposed in the debris flow scar reveal a strong spatial correspondence between elevated piezometric response and water discharging from bedrock fractures. Measurements of apparent root cohesion on the basal (Cb) and lateral (Cl) scarp demonstrate substantial local variability, with areally weighted values of Cb = 0.1 and Cl = 4.6 kPa. Using measured soil properties and basal root strength, the widely used infinite slope model, employed assuming slope parallel groundwater flow, provides a poor prediction of hydrologie conditions at failure. In contrast, a model including lateral root strength (but neglecting lateral frictional strength) gave a predicted critical value of relative soil saturation that fell within the range defined by the arithmetic and geometric mean values at the time of failure. The 3-D slope stability model CLARA-W, used with locally observed pore water pressure, predicted small areas with lower factors of safety within the overall slide mass at sites consistent with field observations of where the failure initiated. This highly variable and localized nature of small areas of high pore pressure that can trigger slope failure means, however, that substantial uncertainty appears inevitable for estimating hydrologie conditions within incipient debris flows under natural conditions. Copyright 2009 by the American Geophysical Union.

Development of an immunochromatographic lateral flow device for rapid diagnosis of Vibrio cholerae O1 serotype Ogawa.

PubMed

Chen, Weixian; Zhang, Jun; Lu, Gang; Yuan, Zuowei; Wu, Qian; Li, Jingjing; Xu, Guiping; He, An; Zheng, Jian; Zhang, Juan

2014-04-01

Cholera is an acute malignant infectious disease caused by the bacteria Vibrio cholerae leading to severe dehydrating diarrhea and vomiting, even high rates of mortality in some cases. However, the prevention of the epidemic disease is achievable if proper sanitation practices are followed, provided the accurate and prompt diagnosis of each prevalent serotype in cholera epidemic. The current gold standard of bacterial culture is inadequate for rapid diagnosis. Our aim is to develop an immunochromatographic test format for O1 serotype Ogawa diagnosis and provide the need for better epidemic prevention and early response. The monoclonal antibodies were raised in conventional method and subsequently screened for a match pair. A variety of related and unrelated bacteria strains recruited were employed to test their sensitivity, specificity etc. by indirect ELISA. The human fecal samples were used to test the final lateral-flow device product to satisfy the measurement requirement. A new monoclonal antibody (McAb) pair, named IXiao₃G₆ and IXiao₁D₉, was generated, which is specifically against V. cholerae O1 serotype Ogawa. Additionally, we developed an immunochromatographic lateral flow device (LFD) using this McAb pair for the highly specific and rapid (5 min) detection of Ogawa. Our product has advantages of simplicity and precision, and can benefit the scene and elementary medical institutions. Copyright © 2013 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

There and Back Again: Development and Regeneration of the Zebrafish Lateral Line System

PubMed Central

Thomas, Eric D.; Cruz, Ivan A.; Hailey, Dale W.; Raible, David W.

2014-01-01

The zebrafish lateral line is a sensory system used to detect changes in water flow. It is comprised of clusters of mechanosensory hair cells called neuromasts. The lateral line is initially established by a migratory group of cells, called a primordium, that deposits neuromasts at stereotyped locations along the surface of the fish. Wnt, FGF, and Notch signaling are all important regulators of various aspects of lateral line development, from primordium migration to hair cell specification. As zebrafish age, the organization of the lateral line becomes more complex in order to accommodate the fish’s increased size. This expansion is regulated by many of the same factors involved in the initial development. Furthermore, unlike mammalian hair cells, lateral line hair cells have the capacity to regenerate after damage. New hair cells arise from the proliferation and differentiation of surrounding support cells, and the molecular and cellular pathways regulating this are beginning to be elucidated. All in all, the zebrafish lateral line has proven to be an excellent model in which to study a diverse array of processes, including collective cell migration, cell polarity, cell fate, and regeneration. PMID:25330982

Development of Lateral Flow Immunochromatographic Strips for Micropollutant Screening Using Colorants of Aptamer-Functionalized Nanogold Particles, Part II: Experimental Verification with Aflatoxin B1 and Chloramphenicol.

PubMed

Zhang, Shan; Zhao, Shuai; Wang, Sai; Liu, Jiahui; Dong, Yiyang

2018-05-09

Lateral flow immunochromatographic strips based on colorants of aptamer-functionalized nanogold particles weredeveloped for the detection of micropollutants aflatoxin B1 (AFB1) and chloramphenicol (CAP). The lateral flow immunochromatographic strip was based on a competitive reaction of thiolated-aptamer between micropollutants and bio-DNA probe-streptavidin as capture material immobilized at the test line. General crucial parameters that might influence the sensitivity have been systematically investigated. To test the effectiveness and applicability of the optimized conditions, two structurally unrelated micropollutants, that is, AFB1 and CAP, were chosen for detection. In the present study, lateral flow immunochromatographic strips for AFB1 and CAP analysis by combining the high selectivity and affinity of aptamers with the unique optical properties of nanogold in municipal water samples were reported for the first time. With the optimized conditions, the immunochromatographic strip showed a visual LOD of 10 ppb and a quantitative LOD of 1.05 ppb using an immunochromatographic reader for AFB1 detection and a quantitative LOD of 63.4 ppb using an immunochromatographic reader for CAP detection. Furthermore, the sensitive strip provided a good linear detection range of approximately 0-50 ppm for AFB1 detection and a wider liner detection range of approximately 0-160 ppm for CAP detection. Moreover, the immunochromatographic strip provided recovery rates for water samples of 90-110% in the AFB1 analysis and 84-108% in the CAP analysis. The results demonstrated that the immunochromatographic strip has excellent potential for wide applicability and verified that the strip methods for the optimized conditions are applicable to a variety of micropollutants. The lateral flow immunochromatographic strip could be used as a simple, rapid, and efficient screening tool for rapid on-site detection of a variety of micropollutants.

Artificial fish skin of self-powered micro-electromechanical systems hair cells for sensing hydrodynamic flow phenomena.

PubMed

Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Miao, Jianmin; Warkiani, Majid Ebrahimi; Triantafyllou, Michael S

2015-10-06

Using biological sensors, aquatic animals like fishes are capable of performing impressive behaviours such as super-manoeuvrability, hydrodynamic flow 'vision' and object localization with a success unmatched by human-engineered technologies. Inspired by the multiple functionalities of the ubiquitous lateral-line sensors of fishes, we developed flexible and surface-mountable arrays of micro-electromechanical systems (MEMS) artificial hair cell flow sensors. This paper reports the development of the MEMS artificial versions of superficial and canal neuromasts and experimental characterization of their unique flow-sensing roles. Our MEMS flow sensors feature a stereolithographically fabricated polymer hair cell mounted on Pb(Zr(0.52)Ti(0.48))O3 micro-diaphragm with floating bottom electrode. Canal-inspired versions are developed by mounting a polymer canal with pores that guide external flows to the hair cells embedded in the canal. Experimental results conducted employing our MEMS artificial superficial neuromasts (SNs) demonstrated a high sensitivity and very low threshold detection limit of 22 mV/(mm s(-1)) and 8.2 µm s(-1), respectively, for an oscillating dipole stimulus vibrating at 35 Hz. Flexible arrays of such superficial sensors were demonstrated to localize an underwater dipole stimulus. Comparative experimental studies revealed a high-pass filtering nature of the canal encapsulated sensors with a cut-off frequency of 10 Hz and a flat frequency response of artificial SNs. Flexible arrays of self-powered, miniaturized, light-weight, low-cost and robust artificial lateral-line systems could enhance the capabilities of underwater vehicles. © 2015 The Author(s).

Artificial fish skin of self-powered micro-electromechanical systems hair cells for sensing hydrodynamic flow phenomena

PubMed Central

Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Miao, Jianmin; Warkiani, Majid Ebrahimi; Triantafyllou, Michael S.

2015-01-01

Using biological sensors, aquatic animals like fishes are capable of performing impressive behaviours such as super-manoeuvrability, hydrodynamic flow ‘vision’ and object localization with a success unmatched by human-engineered technologies. Inspired by the multiple functionalities of the ubiquitous lateral-line sensors of fishes, we developed flexible and surface-mountable arrays of micro-electromechanical systems (MEMS) artificial hair cell flow sensors. This paper reports the development of the MEMS artificial versions of superficial and canal neuromasts and experimental characterization of their unique flow-sensing roles. Our MEMS flow sensors feature a stereolithographically fabricated polymer hair cell mounted on Pb(Zr0.52Ti0.48)O3 micro-diaphragm with floating bottom electrode. Canal-inspired versions are developed by mounting a polymer canal with pores that guide external flows to the hair cells embedded in the canal. Experimental results conducted employing our MEMS artificial superficial neuromasts (SNs) demonstrated a high sensitivity and very low threshold detection limit of 22 mV/(mm s−1) and 8.2 µm s−1, respectively, for an oscillating dipole stimulus vibrating at 35 Hz. Flexible arrays of such superficial sensors were demonstrated to localize an underwater dipole stimulus. Comparative experimental studies revealed a high-pass filtering nature of the canal encapsulated sensors with a cut-off frequency of 10 Hz and a flat frequency response of artificial SNs. Flexible arrays of self-powered, miniaturized, light-weight, low-cost and robust artificial lateral-line systems could enhance the capabilities of underwater vehicles. PMID:26423435

Influence of lateral groundwater flow in a shallow aquifer on eco-hydrological process in a shrub-grass coexistence semiarid area

NASA Astrophysics Data System (ADS)

Wang, Siru; Sun, Jinhua; Lei, Huimin; Zhu, Qiande; Jiang, Sanyuan

2017-04-01

Topography has a considerable influence on eco-hydrological processes resulting from the patterns of solar radiation distribution and lateral water flow. However, not much quantitative information on the contribution of lateral groundwater flow on ecological processes such as vegetation growth and evapo-transpiration is available. To fill this gap, we used a simple eco-hydrological model based on water balance with a 3D groundwater module that uses Darcy's law. This model was applied to a non-contributing area of 50km2 dominated by grassland and shrubland with an underlying shallow aquifer. It was calibrated using manually and remotely sensed vegetation data and water flux data observed by eddy covariance system of two flux towers as well as water table data obtained from HOBO recorders of 40 wells. The results demonstrate that the maximum hydraulic gradient and the maximum flux of lateral groundwater flow reached to 0.156m m-1 and 0.093m3 s-1 respectively. The average annual maximum LAI in grassland, predominantly in low-lying areas, improved by about 5.9% while that in shrubland, predominantly in high-lying areas, remained the same when lateral groundwater flow is considered adequately compared to the case without considering lateral groundwater flow. They also show that LAI is positively and nonlinearly related to evapotranspiration, and that the greater the magnitude of evapotranspiration, the smaller the rate of increase of LAI. The results suggest that lateral groundwater flow should not be neglected when simulating eco-hydrological process in areas with a shallow aquifer.

Behavior of lateral-deformation coefficients during elastoplastic deformation of metals

NASA Astrophysics Data System (ADS)

Zimin, B. A.; Smirnov, I. V.; Sudenkov, Yu. V.

2017-06-01

The results of investigations into variation of the coefficients of lateral deformation (the Poisson ratio) during single-axis tension of samples of steel 12Kh18N10T and St3, titanium VT1, the aluminum alloy D16AM, copper M1, and a magnesium alloy are considered. The technique developed on the basis of the optoacoustic effect and simultaneous measurements of the longitudinal and surface speeds of sound in metallic samples during the tension makes it possible to measure the rates at various stages of the deformation process. The data obtained make it possible to construct the dependences of variation of the lateral-deformation coefficients at all stages of the plastic flow. The correlation of these variations both with known processes of structural reconstructions at various stages of plastic flow and with the process of localization of plastic-shear bands in the aluminum alloy is noted.

A lateral flow assay (LFA) for the rapid detection of extraparenchymal neurocysticercosis using cerebrospinal fluid.

PubMed

Fleury, Agnes; Sastre, Patricia; Sciutto, Edda; Correia, Silvia; Monedero, Alejandro; Toledo, Andrea; Hernandez, Maricela; Harrison, Leslie J S; Parkhouse, R Michael E

2016-10-27

A lateral flow assay (LFA) for the diagnosis and monitoring of extraparenchymal neurocysticercosis, has been developed. The assay is based on the use of the monoclonal antibody HP10, and when applied to cerebrospinal fluid, correctly identified 34 cases of active extraparenchymal neurocysticercosis, but was negative with 26 samples from treated and cured neurocysticercosis patients and with 20 samples from unrelated neurological diseases. There was complete agreement between the HP10 Ag-ELISA results and the HP10-LFA. The HP10-LFA thus has utility for diagnosis and treatment of extraparenchymal neurocysticercosis, frequently a more dangerous form of the infection. Copyright © 2016. Published by Elsevier Inc.

Combined action of transverse oscillations and uniform cross-flow on vortex formation and pattern of a circular cylinder

NASA Astrophysics Data System (ADS)

Lam, K. M.; Liu, P.; Hu, J. C.

2010-07-01

This paper attempts to study the roles of lateral cylinder oscillations and a uniform cross-flow in the vortex formation and wake modes of an oscillating circular cylinder. A circular cylinder is given lateral oscillations of varying amplitudes (between 0.28 and 1.42 cylinder-diameters) in a slow uniform flow stream (Reynolds number=284) to produce the 2S, 2P and P+S wake modes. Detailed flow information is obtained with time-resolved particle-image velocimetry and the phase-locked averaging techniques. In the 2S and 2P mode, the flow speeds relative to the cylinder movement are less than the uniform flow velocity and it is found that initial formation of a vortex is caused by shear-layer separation of the uniform flow on the cylinder. Subsequent development of the shear-layer vortices is affected by the lateral cylinder movement. At small cylinder oscillation amplitudes, vortices are shed in synchronization with the cylinder movement, resulting in the 2S mode. The 2P mode occurs at larger cylinder oscillation amplitudes at which each shear-layer vortex is found to undergo intense stretching and eventual bifurcation into two separate vortices. The P+S mode occurs when the cylinder moving speeds are, for most of the time, higher than the speed of the uniform flow. These situations are found at fast and large-amplitude cylinder oscillations in which the flow relative to the cylinder movement takes over the uniform flow in governing the initial vortex formation. The formation stages of vortices from the cylinder are found to bear close resemblance to those of a vortex street pattern of a cylinder oscillating in an otherwise quiescent fluid at Keulegan-Carpenter numbers around 16. Vortices in the inclined vortex street pattern so formed are then convected downstream by the uniform flow as the vortex pairs in the 2P mode.

Development of a hybrid 3-D hydrological model to simulate hillslopes and the regional unconfined aquifer system in Earth system models

NASA Astrophysics Data System (ADS)

Hazenberg, P.; Broxton, P. D.; Brunke, M.; Gochis, D.; Niu, G. Y.; Pelletier, J. D.; Troch, P. A. A.; Zeng, X.

2015-12-01

The terrestrial hydrological system, including surface and subsurface water, is an essential component of the Earth's climate system. Over the past few decades, land surface modelers have built one-dimensional (1D) models resolving the vertical flow of water through the soil column for use in Earth system models (ESMs). These models generally have a relatively coarse model grid size (~25-100 km) and only account for sub-grid lateral hydrological variations using simple parameterization schemes. At the same time, hydrologists have developed detailed high-resolution (~0.1-10 km grid size) three dimensional (3D) models and showed the importance of accounting for the vertical and lateral redistribution of surface and subsurface water on soil moisture, the surface energy balance and ecosystem dynamics on these smaller scales. However, computational constraints have limited the implementation of the high-resolution models for continental and global scale applications. The current work presents a hybrid-3D hydrological approach is presented, where the 1D vertical soil column model (available in many ESMs) is coupled with a high-resolution lateral flow model (h2D) to simulate subsurface flow and overland flow. H2D accounts for both local-scale hillslope and regional-scale unconfined aquifer responses (i.e. riparian zone and wetlands). This approach was shown to give comparable results as those obtained by an explicit 3D Richards model for the subsurface, but improves runtime efficiency considerably. The h3D approach is implemented for the Delaware river basin, where Noah-MP land surface model (LSM) is used to calculated vertical energy and water exchanges with the atmosphere using a 10km grid resolution. Noah-MP was coupled within the WRF-Hydro infrastructure with the lateral 1km grid resolution h2D model, for which the average depth-to-bedrock, hillslope width function and soil parameters were estimated from digital datasets. The ability of this h3D approach to simulate the hydrological dynamics of the Delaware River basin will be assessed by comparing the model results (both hydrological performance and numerical efficiency) with the standard setup of the NOAH-MP model and a high-resolution (1km) version of NOAH-MP, which also explicitly accounts for lateral subsurface and overland flow.

Distant touch hydrodynamic imaging with an artificial lateral line.

PubMed

Yang, Yingchen; Chen, Jack; Engel, Jonathan; Pandya, Saunvit; Chen, Nannan; Tucker, Craig; Coombs, Sheryl; Jones, Douglas L; Liu, Chang

2006-12-12

Nearly all underwater vehicles and surface ships today use sonar and vision for imaging and navigation. However, sonar and vision systems face various limitations, e.g., sonar blind zones, dark or murky environments, etc. Evolved over millions of years, fish use the lateral line, a distributed linear array of flow sensing organs, for underwater hydrodynamic imaging and information extraction. We demonstrate here a proof-of-concept artificial lateral line system. It enables a distant touch hydrodynamic imaging capability to critically augment sonar and vision systems. We show that the artificial lateral line can successfully perform dipole source localization and hydrodynamic wake detection. The development of the artificial lateral line is aimed at fundamentally enhancing human ability to detect, navigate, and survive in the underwater environment.

Sediment and Vegetation Controls on Delta Channel Networks

NASA Astrophysics Data System (ADS)

Lauzon, R.; Murray, A. B.; Piliouras, A.; Kim, W.

2016-12-01

Numerous factors control the patterns of distributary channels formed on a delta, including water and sediment discharge, grain size, sea level rise rates, and vegetation type. In turn, these channel networks influence the shape and evolution of a delta, including what types of plant and animal life - such as humans - it can support. Previous fluvial modeling and flume experiments, outside of the delta context, have addressed how interactions between sediment and vegetation, through their influence on lateral transport of sediment, determine what type of channel networks develops. Similar interactions likely also shape delta flow patterns. Vegetation introduces cohesion, tending to reduce channel migration rates and strengthen existing channel banks, reinforcing existing channels and resulting in localized, relatively stable flow patterns. On the other hand, sediment transport processes can result in lateral migration and frequent switching of active channels, resulting in flow resembling that of a braided stream. While previous studies of deltas have indirectly explored the effects of vegetation through the introduction of cohesive sediment, we directly incorporate key effects of vegetation on flow and sediment transport into the delta-building model DeltaRCM to explore how these effects influence delta channel network formation. Model development is informed by laboratory flume experiments at UT Austin. Here we present initial results of experiments exploring the effects of sea level rise rate, sediment grain size, vegetation type, and vegetation growth rate on delta channel network morphology. These results support the hypothesis that the ability for lateral transport of sediment to occur plays a key role in determining the evolution of delta channel networks and delta morphology.

A trench study to assess transfer of pesticides in subsurface lateral flow for a soil with contrasting texture on a sloping vineyard in Beaujolais.

PubMed

Peyrard, X; Liger, L; Guillemain, C; Gouy, V

2016-01-01

Subsurface lateral flow in both texture-contrast soils and catchments with shallow bedrock is suspected to be a non-point source of contamination of watercourses by pesticides used in agriculture. As a case study, the north of the Beaujolais region (eastern France) provides a favorable environment for such contamination due to its agro-pedo-climatic conditions. Environments seen in the Beaujolais region include intense viticulture, permeable and shallow soils, steep hillslopes, and storms that occur during the periods of pesticide application. Watercourse contamination by pesticides has been widely observed in this region, and offsite pesticide transport by subsurface lateral flow is suspected to be involved in diffuse and chronic presence of pesticides in surface water. In order to confirm and quantify the potential role of such processes in pesticide transfer, an automated trench system has been designed. The trench was set up on a steep farmed hillslope in a texture-contrast soil. It was equipped with a tipping bucket flow meter and an automatic sampler to monitor pesticide concentrations in lateral flow at fine resolution, by means of a flow-dependent sampling strategy. Four pesticides currently used in vine growing were studied to provide a range of mobility properties: one insecticide (chlorpyrifos-methyl) and three fungicides (spiroxamine, tebuconazole, and dimethomorph). With this system, it was possible to study pesticide concentration dynamics in the subsurface lateral flow, generated by substantial rainfall events following pesticide applications. The experimental design ascertained to be a suitable method in which to monitor subsurface lateral flow and related transfer of pesticides.

Poiseuille's Law--Showing that "p" Is Inversely Proportional to R[superscript 4] Using the Shell Method

ERIC Educational Resources Information Center

Drost, John P.; Georges, Rachel A.

2004-01-01

Jean Poiseuille, a physician, developed a mercury filled U-tube to measure blood pressure in 1828. He discovered that pressure in veins is significantly lower than pressure in arteries. As a result, he studied liquid flow in small tubes. A few years later he established Poiseuille's Law, which states the resistance, "p," of the flow of blood as…

Model reduction of the numerical analysis of Low Impact Developments techniques

NASA Astrophysics Data System (ADS)

Brunetti, Giuseppe; Šimůnek, Jirka; Wöhling, Thomas; Piro, Patrizia

2017-04-01

Mechanistic models have proven to be accurate and reliable tools for the numerical analysis of the hydrological behavior of Low Impact Development (LIDs) techniques. However, their widespread adoption is limited by their complexity and computational cost. Recent studies have tried to address this issue by investigating the application of new techniques, such as surrogate-based modeling. However, current results are still limited and fragmented. One of such approaches, the Model Order Reduction (MOR) technique, can represent a valuable tool for reducing the computational complexity of a numerical problems by computing an approximation of the original model. While this technique has been extensively used in water-related problems, no studies have evaluated its use in LIDs modeling. Thus, the main aim of this study is to apply the MOR technique for the development of a reduced order model (ROM) for the numerical analysis of the hydrologic behavior of LIDs, in particular green roofs. The model should be able to correctly reproduce all the hydrological processes of a green roof while reducing the computational cost. The proposed model decouples the subsurface water dynamic of a green roof in a) one-dimensional (1D) vertical flow through a green roof itself and b) one-dimensional saturated lateral flow along the impervious rooftop. The green roof is horizontally discretized in N elements. Each element represents a vertical domain, which can have different properties or boundary conditions. The 1D Richards equation is used to simulate flow in the substrate and drainage layers. Simulated outflow from the vertical domain is used as a recharge term for saturated lateral flow, which is described using the kinematic wave approximation of the Boussinesq equation. The proposed model has been compared with the mechanistic model HYDRUS-2D, which numerically solves the Richards equation for the whole domain. The HYDRUS-1D code has been used for the description of vertical flow, while a Finite Volume Scheme has been adopted for lateral flow. Two scenarios involving flat and steep green roofs were analyzed. Results confirmed the accuracy of the reduced order model, which was able to reproduce both subsurface outflow and the moisture distribution in the green roof, significantly reducing the computational cost.

Designing for Change: Minimizing the Impact of Changing Requirements in the Later Stages of a Spaceflight Software Project

NASA Technical Reports Server (NTRS)

Allen, B. Danette

1998-01-01

In the traditional 'waterfall' model of the software project life cycle, the Requirements Phase ends and flows into the Design Phase, which ends and flows into the Development Phase. Unfortunately, the process rarely, if ever, works so smoothly in practice. Instead, software developers often receive new requirements, or modifications to the original requirements, well after the earlier project phases have been completed. In particular, projects with shorter than ideal schedules are highly susceptible to frequent requirements changes, as the software requirements analysis phase is often forced to begin before the overall system requirements and top-level design are complete. This results in later modifications to the software requirements, even though the software design and development phases may be complete. Requirements changes received in the later stages of a software project inevitably lead to modification of existing developed software. Presented here is a series of software design techniques that can greatly reduce the impact of last-minute requirements changes. These techniques were successfully used to add built-in flexibility to two complex software systems in which the requirements were expected to (and did) change frequently. These large, real-time systems were developed at NASA Langley Research Center (LaRC) to test and control the Lidar In-Space Technology Experiment (LITE) instrument which flew aboard the space shuttle Discovery as the primary payload on the STS-64 mission.

Reynolds shear stress and heat flux calculations in a fully developed turbulent duct flow

NASA Technical Reports Server (NTRS)

Antonia, R. A.; Kim, J.

1991-01-01

The use of a modified form of the Van Driest mixing length for a fully developed turbulent channel flow leads to mean velocity and Reynolds stress distributions that are in close agreement with data obtained either from experiments or direct numerical simulations. The calculations are then extended to a nonisothermal flow by assuming a constant turbulent Prandtl number, the value of which depends on the molecular Prandtl number. Calculated distributions of mean temperature and lateral heat flux are in reasonable agreement with the simulations. The extension of the calculations to higher Reynolds numbers provides some idea of the Reynolds number required for scaling on wall variables to apply in the inner region of the flow.

Laminar flow control perforated wing panel development

NASA Technical Reports Server (NTRS)

Fischler, J. E.

1986-01-01

Many structural concepts for a wing leading edge laminar flow control hybrid panel were analytically investigated. After many small, medium, and large tests, the selected design was verified. New analytic methods were developed to combine porous titanium sheet bonded to a substructure of fiberglass and carbon/epoxy cloth. At -65 and +160 F test conditions, the critical bond of the porous titanium to the composite failed at lower than anticipated test loads. New cure cycles, design improvements, and test improvements significantly improved the strength and reduced the deflections from thermal and lateral loadings. The wave tolerance limits for turbulence were not exceeded. Consideration of the beam column midbay deflections from the combinations of the axial and lateral loadings and thermal bowing at -65 F, room temperature, and +160 F were included. Many lap shear tests were performed at several cure cycles. Results indicate that sufficient verification was obtained to fabricate a demonstration vehicle.

Multiplexed and portable nucleic acid detection platform with Cas13, Cas12a, and Csm6

PubMed Central

Gootenberg, Jonathan S.; Abudayyeh, Omar O.; Kellner, Max J.; Joung, Julia; Collins, James J.; Zhang, Feng

2018-01-01

Rapid detection of nucleic acids is integral for clinical diagnostics and biotechnological applications. We recently developed a platform termed SHERLOCK (Specific High Sensitivity Enzymatic Reporter UnLOCKing) that combines isothermal pre-amplification with Cas13 to detect single molecules of RNA or DNA. Through characterization of CRISPR enzymology and application development, we report here four advances integrated into SHERLOCKv2: 1) 4-channel single reaction multiplexing using orthogonal CRISPR enzymes; 2) quantitative measurement of input down to 2 aM; 3) 3.5-fold increase in signal sensitivity by combining Cas13 with Csm6, an auxilary CRISPR-associated enzyme; and 4) lateral flow read-out. SHERLOCKv2 can detect Dengue or Zika virus ssRNA as well as mutations in patient liquid biopsy samples via lateral flow, highlighting its potential as a multiplexable, portable, rapid, and quantitative detection platform of nucleic acids. PMID:29449508

Automatic retinal blood flow calculation using spectral domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Wehbe, Hassan; Ruggeri, Marco; Jiao, Shuliang; Gregori, Giovanni; Puliafito, Carmen A.

2008-02-01

Optical Doppler tomography (ODT) is a branch of optical coherence tomography (OCT) that can measure the speed of a blood flow by measuring the Doppler shift impinged on the probing sample light by the moving blood cells. However, the measured speed of blood flow is a function of the Doppler angle, which needs to be determined in order to calculate the absolute velocity of the blood flow inside a vessel. We developed a technique that can extract the Doppler angle from the 3D data measured with spectral-domain OCT, which needs to extract the lateral and depth coordinates of a vessel in each measured ODT and OCT image. The lateral coordinates and the diameter of a blood vessel were first extracted in each OCT structural image by using the technique of blood vessel shadowgram, a technique first developed by us for enhancing the retinal blood vessel contrast in the en face view of the 3D OCT. The depth coordinate of a vessel was then determined by using a circular averaging filter moving in the depth direction along the axis passing through the vessel center in the ODT image. The Doppler angle was then calculated from the extracted coordinates of the blood vessel. The technique was applied in blood flow measurements in retinal blood vessels, which has potential impact on the study and diagnosis of blinding diseases like glaucoma and diabetic retinopathy.

Multiplexed lateral flow biosensors: Technological advances for radically improving point-of-care diagnoses.

PubMed

Li, Jia; Macdonald, Joanne

2016-09-15

Lateral flow biosensors are a leading technology in point-of-care diagnostics due to their simplicity, rapidness and low cost. Their primacy in this arena continues through technological breakthroughs such as multiplexing: the detection of more than one biomarker in a single assay. Multiplexing capacity is critical for improving diagnostic efficiency, enhancing the diagnostic precision for specific diseases and reducing diagnostic cost. Here we review, for the first time, the various types and strategies employed for creating multiplexed lateral flow biosensors. These are classified into four main categories in terms of specific application or multiplexing level, namely linear, parameter, spatial and conceptual. We describe the practical applications and implications for each approach and compare their advantages and disadvantages. Importantly, multiplexing is still subject to limitations of the traditional lateral flow biosensor, such as sensitivity and specificity. However, by pushing the limitations of the traditional medium into the multiplex arena, several technological breakthroughs are emerging with novel solutions that further expand the utility of lateral flow biosensing for point-of-care applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Design and application of a fish-shaped lateral line probe for flow measurement

NASA Astrophysics Data System (ADS)

Tuhtan, J. A.; Fuentes-Pérez, J. F.; Strokina, N.; Toming, G.; Musall, M.; Noack, M.; Kämäräinen, J. K.; Kruusmaa, M.

2016-04-01

We introduce the lateral line probe (LLP) as a measurement device for natural flows. Hydraulic surveys in rivers and hydraulic structures are currently based on time-averaged velocity measurements using propellers or acoustic Doppler devices. The long-term goal is thus to develop a sensor system, which includes spatial gradients of the flow field along a fish-shaped sensor body. Interpreting the biological relevance of a collection of point velocity measurements is complicated by the fact that fish and other aquatic vertebrates experience the flow field through highly dynamic fluid-body interactions. To collect body-centric flow data, a bioinspired fish-shaped probe is equipped with a lateral line pressure sensing array, which can be applied both in the laboratory and in the field. Our objective is to introduce a new type of measurement device for body-centric data and compare its output to estimates of conventional point-based technologies. We first provide the calibration workflow for laboratory investigations. We then provide a review of two velocity estimation workflows, independent of calibration. Such workflows are required as existing field investigations consist of measurements in environments where calibration is not feasible. The mean difference for uncalibrated LLP velocity estimates from 0 to 50 cm/s under in a closed flow tunnel and open channel flume was within 4 cm/s when compared to conventional measurement techniques. Finally, spatial flow maps in a scale vertical slot fishway are compared for the LLP, direct measurements, and 3D numerical models where it was found that the LLP provided a slight overestimation of the current velocity in the jet and underestimated the velocity in the recirculation zone.

Spatially explicit simulation of hydrologically controlled carbon and nitrogen cycles and associated feedback mechanisms in a boreal ecosystem in Eastern Canada.

NASA Astrophysics Data System (ADS)

Govind, A.; Chen, J. M.; Margolis, H.

2007-12-01

Current estimates of terrestrial carbon overlook the effects of topographically-driven lateral flow of soil water. We hypothesize that this component, which occur at a landscape or watershed scale have significant influences on the spatial distribution of carbon, due to its large contribution to the local water balance. To this end, we further developed a spatially explicit ecohydrological model, BEPS-TerrainLab V2.0. We simulated the coupled hydrological and carbon cycle processes in a black spruce-moss ecosystem in central Quebec, Canada. The carbon stocks were initialized using a long term carbon cycling model, InTEC, under a climate change and disturbance scenario, the accuracy of which was determined with inventory plot measurements. Further, we simulated and validated several ecosystem indicators such as ET, GPP, NEP, water table, snow depth and soil temperature, using the measurements for two years, 2004 and 2005. After gaining confidence in the model's ability to simulate ecohydrological processes, we tested the influence of lateral water flow on the carbon cycle. We made three hydrological modeling scenarios 1) Explicit, were realistic lateral water routing was considered 2) Implicit where calculations were based on a bucket modeling approach 3) NoFlow, where the lateral water flow was turned off in the model. The results showed that pronounced anomalies exist among the scenarios for the simulated GPP, ET and NEP. In general, Implicit calculation overestimated GPP and underestimated NEP, as opposed to Explicit simulation. NoFlow underestimated GPP and overestimated NEP. The key processes controlling GPP were manifested through stomatal conductance which reduces under conditions of rapid soil saturation ( NoFlow ) or increases in the Implicit case, and, nitrogen availability which affects Vcmax, the maximum carboxylation rate. However, for NEP, the anomalies were attributed to differences in soil carbon pool decomposition, which determine the heterotrophic respiration and the resultant nitrogen mineralization which affects GPP and several other feedback mechanisms. These results suggest that lateral water flow does play a significant role in the terrestrial carbon distribution. Therefore, regional or global scale terrestrial carbon estimates could have significant errors if proper hydrological constrains are not considered for modeling ecological processes due to large topographic variations on the Earth's surface. For more info please visit: http://ajit.govind.googlepages.com/agu2007

When interflow also percolates: downslope travel distances and hillslope process zones.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jackson, C. Rhett; Bitew, Menberu; Du, Enhao

2014-02-17

In hillslopes with soils characterized by deep regoliths, such as Ultisols,Oxisols, and Alfisols, interflow occurs episodically over impeding layers near and parallel to the soil surface such as low-conductivity B horizons (e.g.Newman et al., 1998; Buttle andMcDonald, 2002; Du et al., In Review), till layers (McGlynn et al., 1999; Bishop et al., 2004), hardpans (McDaniel et al., 2008), C horizons (Detty and McGuire, 2010), and permeable bedrock (Tromp van Meerveld et al., 2007). As perched saturation develops within and above these impeding but permeable horizons, flow moves laterally downslope, but the perched water also continues to percolate through the impedingmore » horizon to the unsaturated soils and saprolite below. Perched water and solutes will eventually traverse the zone of perched saturation above the impeding horizon and then enter and percolate through the impeding horizon. In such flow situations, only lower hillslope segments with sufficient downslope travel distance will deliver water to the riparian zone within the time scale of a storm.farther up the slope, lateral flow within the zone of perched saturation. will act mainly to shift the point of percolation (location where a water packet leaves the downslope flow zone in the upper soil layer and enters the impeding layer) down the hillslope from the point of infiltration. In flatter parts of the hillslope or in areas with little contrast between the conductivities of the upper and impeding soil layers, lateral flow distances will be negligible.« less

An intermediate-scale model for thermal hydrology in low-relief permafrost-affected landscapes

DOE PAGES

Jan, Ahmad; Coon, Ethan T.; Painter, Scott L.; ...

2017-07-10

Integrated surface/subsurface models for simulating the thermal hydrology of permafrost-affected regions in a warming climate have recently become available, but computational demands of those new process-rich simu- lation tools have thus far limited their applications to one-dimensional or small two-dimensional simulations. We present a mixed-dimensional model structure for efficiently simulating surface/subsurface thermal hydrology in low-relief permafrost regions at watershed scales. The approach replaces a full three-dimensional system with a two-dimensional overland thermal hydrology system and a family of one-dimensional vertical columns, where each column represents a fully coupled surface/subsurface thermal hydrology system without lateral flow. The system is then operatormore » split, sequentially updating the overland flow system without sources and the one-dimensional columns without lateral flows. We show that the app- roach is highly scalable, supports subcycling of different processes, and compares well with the corresponding fully three-dimensional representation at significantly less computational cost. Those advances enable recently developed representations of freezing soil physics to be coupled with thermal overland flow and surface energy balance at scales of 100s of meters. Furthermore developed and demonstrated for permafrost thermal hydrology, the mixed-dimensional model structure is applicable to integrated surface/subsurface thermal hydrology in general.« less

Broken flow symmetry explains the dynamics of small particles in deterministic lateral displacement arrays.

PubMed

Kim, Sung-Cheol; Wunsch, Benjamin H; Hu, Huan; Smith, Joshua T; Austin, Robert H; Stolovitzky, Gustavo

2017-06-27

Deterministic lateral displacement (DLD) is a technique for size fractionation of particles in continuous flow that has shown great potential for biological applications. Several theoretical models have been proposed, but experimental evidence has demonstrated that a rich class of intermediate migration behavior exists, which is not predicted. We present a unified theoretical framework to infer the path of particles in the whole array on the basis of trajectories in a unit cell. This framework explains many of the unexpected particle trajectories reported and can be used to design arrays for even nanoscale particle fractionation. We performed experiments that verify these predictions and used our model to develop a condenser array that achieves full particle separation with a single fluidic input.

Surveying unsteady flows by means of movie sequences - A case study

NASA Astrophysics Data System (ADS)

Freymuth, P.; Bank, W.; Finaish, F.

Photographic surveying techniques and their results are presented for vortical pattern development in unsteady two-dimensional flows, which depends on a multitude of parameters that have heretofore hampered broad investigation, in order to delineate the more important parametric dependencies. Samples are given from 100 films representing over 2000 sequences consisting of 400,000 photographic frames. Attention is given to the problems posed by resolution of time and lateral dimensions, spanwise vortical structure, and the dependence of angle of attack on Reynolds number and flow geometry.

Mitigating the Hook Effect in Lateral Flow Sandwich Immunoassays Using Real-Time Reaction Kinetics.

PubMed

Rey, Elizabeth G; O'Dell, Dakota; Mehta, Saurabh; Erickson, David

2017-05-02

The quantification of analyte concentrations using lateral flow assays is a low-cost and user-friendly alternative to traditional lab-based assays. However, sandwich-type immunoassays are often limited by the high-dose hook effect, which causes falsely low results when analytes are present at very high concentrations. In this paper, we present a reaction kinetics-based technique that solves this problem, significantly increasing the dynamic range of these devices. With the use of a traditional sandwich lateral flow immunoassay, a portable imaging device, and a mobile interface, we demonstrate the technique by quantifying C-reactive protein concentrations in human serum over a large portion of the physiological range. The technique could be applied to any hook effect-limited sandwich lateral flow assay and has a high level of accuracy even in the hook effect range.

Battery operated preconcentration-assisted lateral flow assay.

PubMed

Kim, Cheonjung; Yoo, Yong Kyoung; Han, Sung Il; Lee, Junwoo; Lee, Dohwan; Lee, Kyungjae; Hwang, Kyo Seon; Lee, Kyu Hyoung; Chung, Seok; Lee, Jeong Hoon

2017-07-11

Paper-based analytical devices (e.g. lateral flow assays) are highly advantageous as portable diagnostic systems owing to their low costs and ease of use. Because of their low sensitivity and detection limits for biomolecules, these devices have several limitations in applications for real-field diagnosis. Here, we demonstrate a paper-based preconcentration enhanced lateral flow assay using a commercial β-hCG-based test. Utilizing a simple 9 V battery operation with a low power consumption of approximately 81 μW, we acquire a 25-fold preconcentration factor, demonstrating a clear sensitivity enhancement in the colorimetric lateral flow assay; consequently, clear colors are observed in a rapid kit test line, which cannot be monitored without preconcentration. This device can also facilitate a semi-quantitative platform using the saturation value and/or color intensity in both paper-based colorimetric assays and smartphone-based diagnostics.

Internal flows and force matrices in axial flow inducers

NASA Astrophysics Data System (ADS)

Bhattacharyya, Abhijit

1994-01-01

Axial flow inducers such as those used in high speed rocket engine turbopumps are subject to complex internal flows and fluid-induced lateral and rotordynamic forces. An investigation of these internal flows was conducted using boundary layer flow visualization on the blades, hub and housing of unshrouded and shrouded inducers. Results showed that the blade boundary layer flows have strong radial components at off-design conditions and remain attached to the blade surface at all flow coefficients tested. The origin of upstream swirling backflow was found to be at the discharge plane of the inducer. In addition, flow reversal was observed at the suction side blade tip near the leading edge in a shrouded inducer. Re-entry of the hub boundary layer flow, a downstream backflow, into the blade passage area was observed at flow coefficients below design. For unshrouded inducers the radially outward flow near the blade tip mixed with the leakage flow to form the upstream backflow. The lateral and rotordynamic forces acting on an inducer due to an imposed whirl motion was also investigated at various flow coefficients. It was found that the rotordynamic force data at various whirl frequency ratios does not allow a normal quadratic fit; consequently the conventional inertial, stiffness and damping coefficients cannot be obtained and a definite whirl ratio describing the instability region does not result. Application of an actuator disk theory proved to be inaccurate in estimating the rotordynamic tangential force in a non-whirling inducer. The effect of upstream and downstream flow distortions on the rotordynamic and lateral forces on an inducer were studied. It was found that at flow coefficients below design, large lateral forces occurred in the presence of a downstream asymmetry. Results of inlet distortion experiments show that a strong inlet shear causes a significant increase in the lateral force. Cavitation was found to have important consequences for fluid-induced rotordynamic forces. These forces become destabilizing for both forward and reverse whirl. Decreasing cavitation numbers caused an increase in the magnitudes of the destabilizing forces.

Quasi-radial wall jets as a new concept in boundary layer flow control

NASA Astrophysics Data System (ADS)

Javadi, Khodayar; Hajipour, Majid

2018-01-01

This work aims to introduce a novel concept of wall jets wherein the flow is radially injected into a medium through a sector of a cylinder, called quasi-radial (QR) wall jets. The results revealed that fluid dynamics of the QR wall jet flow differs from that of conventional wall jets. Indeed, lateral and normal propagations of a conventional three-dimensional wall jet are via shear stresses. While, lateral propagation of a QR wall jet is due to mean lateral component of the velocity field. Moreover, discharged Arrays of conventional three-dimensional wall jets in quiescent air lead to formation of a combined wall jet at large distant from the nozzles, while QR wall jet immediately spread in lateral direction, meet each other and merge together very quickly in a short distance downstream of the jet nozzles. Furthermore, in discharging the conventional jets into an external flow, there is no strong interaction between them as they are moving parallel. While, in QR wall jets the lateral components of the velocity field strongly interact with boundary layer of the external flow and create strong helical vortices acting as vortex generators.

Flow processes in overexpanded chemical rocket nozzles. Part 2: Side loads due to asymmetric separation

NASA Technical Reports Server (NTRS)

Schmucker, R. H.

1984-01-01

Methods for measuring the lateral forces, occurring as a result of asymmetric nozzle flow separation, are discussed. The effect of some parameters on the side load is explained. A new method was developed for calculation of the side load. The values calculated are compared with side load data of the J-2 engine. Results are used for predicting side loads of the space shuttle main engine.

4D Floodplain representation in hydrologic flood forecasting using WRFHydro modeling framework

NASA Astrophysics Data System (ADS)

Gangodagamage, C.; Li, Z.; Adams, T.; Ito, T.; Maitaria, K.; Islam, M.; Dhondia, J.

2015-12-01

Floods claim more lives and damage more property than any other category of natural disaster in the Continental U.S. A system that can demarcate local flood boundaries dynamically could help flood prone communities prepare for and even prevent from catastrophic flood events. Lateral distance from the centerline of the river to the right and left floodplains for the water levels coming out of the models at each grid location have not been properly integrated with the national hydrography dataset (NHDPlus). The NHDPlus dataset represents the stream network with feature classes such as rivers, tributaries, canals, lakes, ponds, dams, coastlines, and stream gages. The NHDPlus dataset consists of approximately 2.7 million river reaches defining how surface water drains to the ocean. These river reaches have upstream and downstream nodes and basic parameters such as flow direction, drainage area, reach slope etc. We modified an existing algorithm (Gangodagamage et al., 2007, 2011) to provide lateral distance from the centerline of the river to the right and left floodplains for the flows simulated by models. Previous work produced floodplain boundaries for static river stages (i.e. 3D metric: distance along the main stem, flow depth, lateral distance from river center line). Our new approach introduces the floodplain boundary for variable water levels with the fourth dimension, time. We use modeled flows from WRFHydro and demarcate the right and left lateral boundaries of inundation dynamically. This approach dynamically integrates with high resolution models (e.g., hourly and ~ 1 km spatial resolution) that are developed from recent advancements in high computational power with ground based measurements (e.g., Fluxnet), lateral inundation vectors (direction and spatial extent) derived from multi-temporal remote sensing data (e.g., LiDAR, WorldView 2, Landsat, ASTER, MODIS), and improved representations of the physical processes through multi-parameterizations. Our approach enhances the normalized (streams are at zero elevations) DEM derived upstream flow routing pathways for stream reaches for given water stages as more and more satellite data become available for various flood inundations. Validation of the inundation boundaries is performed using HEC-RAS hydrodynamic model results for selected streams.

Calibration strategies for a groundwater model in a highly dynamic alpine floodplain

USGS Publications Warehouse

Foglia, L.; Burlando, P.; Hill, Mary C.; Mehl, S.

2004-01-01

Most surface flows to the 20-km-long Maggia Valley in Southern Switzerland are impounded and the valley is being investigated to determine environmental flow requirements. The aim of the investigation is the devel-opment of a modelling framework that simulates the dynamics of the ground-water, hydrologic, and ecologic systems. Because of the multi-scale nature of the modelling framework, large-scale models are first developed to provide the boundary conditions for more detailed models of reaches that are of eco-logical importance. We describe here the initial (large-scale) groundwa-ter/surface water model and its calibration in relation to initial and boundary conditions. A MODFLOW-2000 model was constructed to simulate the inter-action of groundwater and surface water and was developed parsimoniously to avoid modelling artefacts and parameter inconsistencies. Model calibration includes two steady-state conditions, with and without recharge to the aquifer from the adjoining hillslopes. Parameters are defined to represent areal re-charge, hydraulic conductivity of the aquifer (up to 5 classes), and streambed hydraulic conductivity. Model performance was investigated following two system representation. The first representation assumed unknown flow input at the northern end of the groundwater domain and unknown lateral inflow. The second representation used simulations of the lateral flow obtained by means of a raster-based, physically oriented and continuous in time rainfall-runoff (R-R) model. Results based on these two representations are compared and discussed.

Conceptualization and analysis of ground-water flow system in the Coastal Plain of Virginia and adjacent parts of Maryland and North Carolina

USGS Publications Warehouse

Harsh, John F.; Laczniak, Randell J.

1990-01-01

The ground-water flow system in the Coastal Plain of Virginia and adjacent parts of Maryland and North Carolina consists of a water table aquifer and an underlying sequence of confined aquifers and intervening confining units composed of unconsolidated sand and clay. A digital flow model was developed to enhance knowledge of the behavior of the ground-water flow system in response to its development. Ten pumping periods covering 90 yr of withdrawal simulated the history of ground-water development. Simulated potentiometric-surface maps for 1980 show lowered water levels and the development of coalescing cones of depression around the cities of Franklin, Suffolk, and Williamsburg and the town of West Point, all in Virginia. The largest simulated decline in water level, about 210 ft was near Franklin. Water budgets indicate that over the period of simulation (1891-1980): (1) pumpage from the model area increased by about 105 Mgal/d; (2) lateral boundary outflow increased by about 5 Mgal/d; (3) ground-water flow to streams and coastal water decreased by about 107.5 Mgal/d; (4) lateral boundary inflow increased by about 0.7 Mgal/d, and (5) water released from aquifer storage increased by about 1.6 Mgal/d. Simulated rates of recharge into the confined aquifer system at the end of the final pumping period (1980) varied up to 3.8 in/yr. and simulated rates of discharge out of the confined system varied up to 2.2 in/yr. Results of simulations show an increase of about 110 Mgal/d into the confined system from the unconfined system over the period of simulation. This increase in flow into the confined system affected local discharge of ground water to streams and regional discharge to coastal water. Lowering the storage coefficient of the aquifer had a minimal effect simulated water levels, whereas increasing the storage coefficient had a much more significant effect.

Rolling with the flow: bumblebees flying in unsteady wakes.

PubMed

Ravi, Sridhar; Crall, James D; Fisher, Alex; Combes, Stacey A

2013-11-15

Our understanding of how variable wind in natural environments affects flying insects is limited because most studies of insect flight are conducted in either smooth flow or still air conditions. Here, we investigate the effects of structured, unsteady flow (the von Karman vortex street behind a cylinder) on the flight performance of bumblebees (Bombus impatiens). Bumblebees are 'all-weather' foragers and thus frequently experience variable aerial conditions, ranging from fully mixed, turbulent flow to unsteady, structured vortices near objects such as branches and stems. We examined how bumblebee flight performance differs in unsteady versus smooth flow, as well as how the orientation of unsteady flow structures affects their flight performance, by filming bumblebees flying in a wind tunnel under various flow conditions. The three-dimensional flight trajectories and orientations of bumblebees were quantified in each of three flow conditions: (1) smooth flow, (2) the unsteady wake of a vertical cylinder (inducing strong lateral disturbances) and (3) the unsteady wake of a horizontal cylinder (inducing strong vertical disturbances). In both unsteady conditions, bumblebees attenuated the disturbances induced by the wind quite effectively, but still experienced significant translational and rotational fluctuations as compared with flight in smooth flow. Bees appeared to be most sensitive to disturbance along the lateral axis, displaying large lateral accelerations, translations and rolling motions in response to both unsteady flow conditions, regardless of orientation. Bees also displayed the greatest agility around the roll axis, initiating voluntary casting maneuvers and correcting for lateral disturbances mainly through roll in all flow conditions. Both unsteady flow conditions reduced the upstream flight speed of bees, suggesting an increased cost of flight in unsteady flow, with potential implications for foraging patterns and colony energetics in natural, variable wind environments.

How bumblebees use lateral and ventral optic flow cues for position control in environments of different proximity.

PubMed

Linander, Nellie; Baird, Emily; Dacke, Marie

2017-05-01

Flying insects frequently navigate through environments of different complexity. In this study, buff-tailed bumblebees (Bombus terrestris L.) were trained to fly along tunnels of different widths, from 60 to 240 cm. In tunnel widths of 60 and 120 cm, bumblebees control their lateral position by balancing the magnitude of translational optic flow experienced in the lateral visual field of each eye. In wider tunnels, bumblebees use translational optic flow cues in the ventral visual field to control their lateral position and to steer along straight tracks. Our results also suggest that bumblebees prefer to fly over surfaces that provide strong ventral optic flow cues, rather than over featureless ones. Together, these strategies allow bumblebees to minimize the risk of collision and to maintain relatively straight flight paths in a broad range of environments.

High-Speed Lateral Flow Strategy for a Fast Biosensing with an Improved Selectivity and Binding Affinity.

PubMed

Cho, Dong Guk; Yoo, Haneul; Lee, Haein; Choi, Yeol Kyo; Lee, Minju; Ahn, Dong June; Hong, Seunghun

2018-05-10

We report a high-speed lateral flow strategy for a fast biosensing with an improved selectivity and binding affinity even under harsh conditions. In this strategy, biosensors were fixed at a location away from the center of a round shape disk, and the disk was rotated to create the lateral flow of a target solution on the biosensors during the sensing measurements. Experimental results using the strategy showed high reaction speeds, high binding affinity, and low nonspecific adsorptions of target molecules to biosensors. Furthermore, binding affinity between target molecules and sensing molecules was enhanced even in harsh conditions such as low pH and low ionic strength conditions. These results show that the strategy can improve the performance of conventional biosensors by generating high-speed lateral flows on a biosensor surface. Therefore, our strategy can be utilized as a simple but powerful tool for versatile bio and medical applications.

A Lateral Flow Biosensor for the Detection of Single Nucleotide Polymorphisms.

PubMed

Zeng, Lingwen; Xiao, Zhuo

2017-01-01

A lateral flow biosensor (LFB) is introduced for the detection of single nucleotide polymorphisms (SNPs). The assay is composed of two steps: circular strand displacement reaction and lateral flow biosensor detection. In step 1, the nucleotide at SNP site is recognized by T4 DNA ligase and the signal is amplified by strand displacement DNA polymerase, which can be accomplished at a constant temperature. In step 2, the reaction product of step 1 is detected by a lateral flow biosensor, which is a rapid and cost effective tool for nuclei acid detection. Comparing with conventional methods, it requires no complicated machines. It is suitable for the use of point of care diagnostics. Therefore, this simple, cost effective, robust, and promising LFB detection method of SNP has great potential for the detection of genetic diseases, personalized medicine, cancer related mutations, and drug-resistant mutations of infectious agents.

The treatment of pseudoaneurysms with flow diverters after malignant otitis externa.

PubMed

Németh, Tamás; Szakács, László; Bella, Zsolt; Majoros, Valéria; Barzó, Pál; Vörös, Erika

2017-12-01

Background We report a case of bilateral malignant otitis externa complicated with bilateral petrous internal carotid artery pseudoaneurysms and their successful treatment with a flow diverter. Case report A 68-year-old woman with serious complications of type II diabetes mellitus had malignant otitis externa on the right side. She was treated with combined antibiotic therapy and underwent mastoidectomy for mastoiditis. She presented at our hospital with acute hemorrhage from the right external auditory canal. The emergency computed tomography (CT) angiography revealed a multiobulated pseudoaneurysm at the petrous segment of the right internal carotid artery. The pseudoaneurysm was treated with a 5 × 40-mm Surpass flow diverter. Three months later, she developed a malignant external otitis on the left side. As the infection progressed, a left-sided mastoiditis, a brain abscess, and a pseudoaneurysm at the petrous segment of the left internal carotid artery developed. The pseudoaneurysm caused bleeding from the left ear, and was treated with a 5 × 50-mm Surpass flow diverter. No recurrent bleeding was observed. Four months later, a follow-up angiography showed complete occlusion of the pseudoaneurysm on the left side, but a residual aneurysm could be detected on the right side. One year after the first intervention, the follow-up CT and magnetic resonance angiography revealed the complete occlusion of the aneurysms bilaterally. Conclusion The use of a flow diverter appears to be an efficient and safe method to occlude carotid pseudoaneurysms even in an inflammatory milieu.

Thermal effects of groundwater flow through subarctic fens: A case study based on field observations and numerical modeling

DOE PAGES

Sjöberg, Ylva; Coon, Ethan; K. Sannel, A. Britta; ...

2016-02-04

Modeling and observation of ground temperature dynamics are the main tools for understanding current permafrost thermal regimes and projecting future thaw. Until recently, most studies on permafrost have focused on vertical ground heat fluxes. Groundwater can transport heat in both lateral and vertical directions but its influence on ground temperatures at local scales in permafrost environments is not well understood. In this paper, we combine field observations from a subarctic fen in the sporadic permafrost zone with numerical simulations of coupled water and thermal fluxes. At the Tavvavuoma study site in northern Sweden, ground temperature profiles and groundwater levels weremore » observed in boreholes. These observations were used to set up one- and two-dimensional simulations down to 2 m depth across a gradient of permafrost conditions within and surrounding the fen. Two-dimensional scenarios representing the fen under various hydraulic gradients were developed to quantify the influence of groundwater flow on ground temperature. Our observations suggest that lateral groundwater flow significantly affects ground temperatures. This is corroborated by modeling results that show seasonal ground ice melts 1 month earlier when a lateral groundwater flux is present. Further, although the thermal regime may be dominated by vertically conducted heat fluxes during most of the year, isolated high groundwater flow rate events such as the spring freshet are potentially important for ground temperatures. Finally, as sporadic permafrost environments often contain substantial portions of unfrozen ground with active groundwater flow paths, knowledge of this heat transport mechanism is important for understanding permafrost dynamics in these environments.« less

Broken flow symmetry explains the dynamics of small particles in deterministic lateral displacement arrays

PubMed Central

Kim, Sung-Cheol; Wunsch, Benjamin H.; Hu, Huan; Smith, Joshua T.; Stolovitzky, Gustavo

2017-01-01

Deterministic lateral displacement (DLD) is a technique for size fractionation of particles in continuous flow that has shown great potential for biological applications. Several theoretical models have been proposed, but experimental evidence has demonstrated that a rich class of intermediate migration behavior exists, which is not predicted. We present a unified theoretical framework to infer the path of particles in the whole array on the basis of trajectories in a unit cell. This framework explains many of the unexpected particle trajectories reported and can be used to design arrays for even nanoscale particle fractionation. We performed experiments that verify these predictions and used our model to develop a condenser array that achieves full particle separation with a single fluidic input. PMID:28607075

The inviscid stability of supersonic flow past a sharp cone

NASA Technical Reports Server (NTRS)

Duck, Peter W.; Shaw, Stephen J.

1990-01-01

The effects of lateral curvature on the development of supersonic laminar inviscid boundary-layer flow on a sharp cone with adiabatic wall conditions are investigated analytically, with a focus on the linear temporal inviscid stability properties. The derivation of the governing equations and of a 'triply generalized' inflexion condition is outlined, and numerical results for freestream Mach number 3.8 are presented in extensive graphs and characterized in detail. A third instability mode related to the viscous mode observed by Duck and Hall (1990) using triple-deck theory is detected and shown to be more unstable and to have larger growth rates than the second mode in some cases. It is found that the 'sonic' neutral mode is affected by the lateral curvature and becomes a supersonic neutral mode.

A Lateral Flow Rapid Test for Human Toxocariasis Developed Using Three Toxocara canis Recombinant Antigens.

PubMed

Yunus, Muhammad Hafiznur; Tan Farrizam, Siti Naqiuyah; Abdul Karim, Izzati Zahidah; Noordin, Rahmah

2018-01-01

Laboratory diagnosis of toxocariasis is still a challenge especially in developing endemic countries with polyparasitism. In this study, three Toxocara canis recombinant antigens, rTES-26, rTES-30, and rTES-120, were expressed and used to prepare lateral flow immunoglobulin G4 (IgG4) dipsticks. The concordance of the results of the rapid test (comprising three dipsticks) with a commercial IgG-enzyme-linked immunosorbent assay (ELISA) (Cypress Diagnostics, Belgium) was compared against the concordance of two other commercial IgG-ELISA kits (Bordier, Switzerland and NovaTec, Germany) with the Cypress kit. Using Toxocara- positive samples, the concordance of the dipstick dotted with rTES-26, rTES-30, and rTES-120 was 41.4% (12/29), 51.7% (15/29), and 72.4% (21/29), respectively. When positivity with any dipstick was considered as an overall positive rapid test result, the concordance with the Cypress kit was 93% (27/29). Meanwhile, when compared with the results of the Cypress kit, the concordance of IgG-ELISA from NovaTec and Bordier was 100% (29/29) and 89.7% (26/29), respectively. Specific IgG4 has been recognized as a marker of active infection for several helminthic diseases; therefore, the two non-concordant results of the rapid test when compared with the NovaTec IgG-ELISA kit may be from samples of people with non-active infection. All the three dipsticks showed 100% (50/50) concordance with the Cypress kit when tested with serum from individuals who were healthy and with other infections. In conclusion, the lateral flow rapid test is potentially a good, fast, and easy test for toxocariasis. Next, further validation studies and development of a test with the three antigens in one dipstick will be performed.

Effects of slope on the dynamics of dilute pyroclastic density currents from May 18th, 1980 Mt. St. Helens eruption

NASA Astrophysics Data System (ADS)

Bendana, S.; Self, S.; Dufek, J.

2012-12-01

The infamous, May 18th, 1980 eruption of Mt St Helens in the state of Washington produced several episodes of pyroclastic density currents (PDCs) including the initial lateral blast, which traveled nearly 30 km, and later PDCs, which filled in the area up to 8 km north of the volcano. The focus of this research is on the later PDCs, which differed from the lateral blast in that they have a higher particle concentration and filled in the topography up to 40 m. While the concentrated portions of the afternoon PDCs followed deep topographic drainages down the steep flanks of the volcano, the dilute overriding cloud partially decoupled to develop fully dilute, turbulent PDCs on the flanks of the volcano (Beeson, D.L. 1988. Proximal Flank Facies of the May 18, 1980 Ignimbrite: Mt. St. Helens, Washington.). The dilute PDCs deposited thin, cross-stratified and stratified pyroclastic deposits, known as the proximal bedded deposits, which differ greatly in depositional characteristics from the thick, massive, poorly-sorted, block-rich deposits associated with the more concentrated portions of the flow. We explore the influence of topography on the formation of these dilute currents and influence of slope on the currents transport and depositional mechanisms. The deposits on steeper slopes (>15°) are fines depleted relative to the proximal bedded deposits on shallower slopes (<15°). Bedform amplitude and wavelength increase with increasing slope, as does the occurrence of regressive dunes. Increasing slope causes an increase in flow velocity and thus an increase in flow turbulence. The fines depleted deposits suggest that fine ash elutriation is more efficient in flows with stronger turbulence. The longer wavelength and amplitudes suggest that bedform morphology is directly related to flow velocity, an important finding since the controls on bedform wavelength and amplitude in density stratified flows remains poorly constrained. The occurrence of regressive dunes, often interpreted as high flow-regime bedforms, on steeper slopes relative to progressive dunes on shallower slopes further attests to the control of velocity and flow regime on bedform morphology. Samples collected from recently exposed deposits and analyzed by grain size measurements, density analyses, and crystal morphoscopy studies further assess modes of origin and transport of dilute PDCs. The collected data will be used to validate numerical models that attempt to quantify the hazards of decoupled, dilute PDCs.

Force determination in lateral magnetic tweezers combined with TIRF microscopy.

PubMed

Madariaga-Marcos, J; Hormeño, S; Pastrana, C L; Fisher, G L M; Dillingham, M S; Moreno-Herrero, F

2018-03-01

Combining single-molecule techniques with fluorescence microscopy has attracted much interest because it allows the correlation of mechanical measurements with directly visualized DNA : protein interactions. In particular, its combination with total internal reflection fluorescence microscopy (TIRF) is advantageous because of the high signal-to-noise ratio this technique achieves. This, however, requires stretching long DNA molecules across the surface of a flow cell to maximize polymer exposure to the excitation light. In this work, we develop a module to laterally stretch DNA molecules at a constant force, which can be easily implemented in regular or combined magnetic tweezers (MT)-TIRF setups. The pulling module is further characterized in standard flow cells of different thicknesses and glass capillaries, using two types of micrometer size superparamagnetic beads, long DNA molecules, and a home-built device to rotate capillaries with mrad precision. The force range achieved by the magnetic pulling module was between 0.1 and 30 pN. A formalism for estimating forces in flow-stretched tethered beads is also proposed, and the results compared with those of lateral MT, demonstrating that lateral MT achieve higher forces with lower dispersion. Finally, we show the compatibility with TIRF microscopy and the parallelization of measurements by characterizing DNA binding by the centromere-binding protein ParB from Bacillus subtilis. Simultaneous MT pulling and fluorescence imaging demonstrate the non-specific binding of BsParB on DNA under conditions restrictive to condensation.

Electrospin-coating of nitrocellulose membrane enhances sensitivity in nucleic acid-based lateral flow assay.

PubMed

Yew, Chee-Hong Takahiro; Azari, Pedram; Choi, Jane Ru; Li, Fei; Pingguan-Murphy, Belinda

2018-06-07

Point-of-care biosensors are important tools developed to aid medical diagnosis and testing, food safety and environmental monitoring. Paper-based biosensors, especially nucleic acid-based lateral flow assays (LFA), are affordable, simple to produce and easy to use in remote settings. However, the sensitivity of such assays to infectious diseases has always been a restrictive challenge. Here, we have successfully electrospun polycaprolactone (PCL) on nitrocellulose (NC) membrane to form a hydrophobic coating to reduce the flow rate and increase the interaction rate between the targets and gold nanoparticles-detecting probes conjugates, resulting in the binding of more complexes to the capture probes. With this approach, the sensitivity of the PCL electrospin-coated test strip has been increased by approximately ten-fold as compared to the unmodified test strip. As a proof of concept, this approach holds great potential for sensitive detection of targets at point-of-care testing. Copyright © 2018 Elsevier B.V. All rights reserved.

A new paper-based platform technology for point-of-care diagnostics.

PubMed

Gerbers, Roman; Foellscher, Wilke; Chen, Hong; Anagnostopoulos, Constantine; Faghri, Mohammad

2014-10-21

Currently, the Lateral flow Immunoassays (LFIAs) are not able to perform complex multi-step immunodetection tests because of their inability to introduce multiple reagents in a controlled manner to the detection area autonomously. In this research, a point-of-care (POC) paper-based lateral flow immunosensor was developed incorporating a novel microfluidic valve technology. Layers of paper and tape were used to create a three-dimensional structure to form the fluidic network. Unlike the existing LFIAs, multiple directional valves are embedded in the test strip layers to control the order and the timing of mixing for the sample and multiple reagents. In this paper, we report a four-valve device which autonomously directs three different fluids to flow sequentially over the detection area. As proof of concept, a three-step alkaline phosphatase based Enzyme-Linked ImmunoSorbent Assay (ELISA) protocol with Rabbit IgG as the model analyte was conducted to prove the suitability of the device for immunoassays. The detection limit of about 4.8 fm was obtained.

Phase Resolved Angular Velocity Control of Cross Flow Turbines

NASA Astrophysics Data System (ADS)

Strom, Benjamin; Brunton, Steven; Polagye, Brian

2015-11-01

Cross flow turbines have a number of operational advantages for the conversion of kinetic energy in marine or fluvial currents, but they are often less efficient than axial flow devices. Here a control scheme is presented in which the angular velocity of a cross flow turbine with two straight blades is prescribed as a function of azimuthal blade position, altering the time-varying effective angle of attack. Flume experiments conducted with a scale model turbine show approximately an 80% increase in turbine efficiency versus optimal constant angular velocity and constant resistive torque control schemes. Torque, drag, and lateral forces on one- and two-bladed turbines are analyzed and interpreted with bubble flow visualization to develop a simple model that describes the hydrodynamics responsible for the observed increase in mean efficiency. Challenges associated with implementing this control scheme on commercial-scale devices are discussed. If solutions are found, the performance increase presented here may impact the future development of cross flow turbines.

Lateral fluid flow in a compacting sand-shale sequence: South Caspian basin.

USGS Publications Warehouse

Bredehoeft, J.D.; Djevanshir, R.D.; Belitz, K.R.

1988-01-01

The South Caspian basin contains both sands and shales that have pore-fluid pressures substantially in excess of hydrostatic fluid pressure. Pore-pressure data from the South Caspian basin demonstrate that large differences in excess hydraulic head exist between sand and shale. The data indicate that sands are acting as drains for overlying and underlying compacting shales and that fluid flows laterally through the sand on a regional scale from the basin interior northward to points of discharge. The major driving force for the fluid movement is shale compaction. We present a first- order mathematical analysis in an effort to test if the permeability of the sands required to support a regional flow system is reasonable. The results of the analysis suggest regional sand permeabilities ranging from 1 to 30 md; a range that seems reasonable. This result supports the thesis that lateral fluid flow is occurring on a regional scale within the South Caspian basin. If vertical conduits for flow exist within the basin, they are sufficiently impermeable and do not provide a major outlet for the regional flow system. The lateral fluid flow within the sands implies that the stratigraphic sequence is divided into horizontal units that are hydraulically isolated from one another, a conclusion that has important implications for oil and gas migration.-Authors

Recombinase polymerase amplification (RPA) combined with lateral flow (LF) strip for equipment-free detection of Cryptosporidium spp. oocysts in dairy cattle feces.

PubMed

Wu, Yao-Dong; Zhou, Dong-Hui; Zhang, Long-Xian; Zheng, Wen-Bin; Ma, Jian-Gang; Wang, Meng; Zhu, Xing-Quan; Xu, Min-Jun

2016-09-01

Cryptosporidium is a widespread protozoan parasite that infects a large number of vertebrate animals, resulting in varying degrees of diarrhea or even death. As dairy cattle feces is an important source of Cryptosporidium spp. infection, development of a handy and accurate detection method via its oocysts in dairy cattle feces would be interesting and necessary. We herein developed a quick detecting method using recombinase polymerase amplification (RPA) combined with lateral flow (LF) strip to detect DNA of Cryptosporidium oocysts in dairy cattle feces. The DNA was released by boiled water with 0.1 % N-lauroylsarcosine sodium salt (LSS). The established method was proven to be of higher sensitivity than normal polymerase chain reaction (PCR) amplification with the lowest detection of 0.5 oocyst per reaction, and specificity with no cross reactivity to other common protozoan species in the intestine of dairy cattle. The diagnostic method established herein is simple, rapid, and cost-effective, and has potential for further development as a diagnostic kit for the diagnosis of cryptosporidiosis of dairy cattle.

Interaction of lateral baroclinic forcing and turbulence in an estuary

USGS Publications Warehouse

Lacy, J.R.; Stacey, M.T.; Burau, J.R.; Monismith, Stephen G.

2003-01-01

Observations of density and velocity in a channel in northern San Francisco Bay show that the onset of vertical density stratification during flood tides is controlled by the balance between the cross-channel baroclinic pressure gradient and vertical mixing due to turbulence. Profiles of velocity, salinity, temperature, and suspended sediment concentration were measured in transects across Suisun Cutoff, in northern San Francisco Bay, on two days over the 12.5-hour tidal cycle. During flood tides an axial density front developed between fresher water flowing from the shallows of Grizzly Bay into the northern side of Suisun Cutoff and saltier water flowing up the channel. North of the front, transverse currents were driven by the lateral salinity gradient, with a top-to-bottom velocity difference greater than 30 cm/s. South of the front, the secondary circulation was weak, and along-channel velocities were greater than to the north. The gradient Richardson number shows that stratification was stable north of the front, while the water column was turbulently mixed south of the front. Time-series measurements of velocity and salinity demonstrate that the front develops during each tidal cycle. In estuaries, longitudinal dynamics predict less stratification during flood than ebb tides. These data show that stratification can develop during flood tides due to a lateral baroclinic pressure gradient in estuaries with complex bathymetry.

Design requirements and development of an airborne descent path definition algorithm for time navigation

NASA Technical Reports Server (NTRS)

Izumi, K. H.; Thompson, J. L.; Groce, J. L.; Schwab, R. W.

1986-01-01

The design requirements for a 4D path definition algorithm are described. These requirements were developed for the NASA ATOPS as an extension of the Local Flow Management/Profile Descent algorithm. They specify the processing flow, functional and data architectures, and system input requirements, and recommended the addition of a broad path revision (reinitialization) function capability. The document also summarizes algorithm design enhancements and the implementation status of the algorithm on an in-house PDP-11/70 computer. Finally, the requirements for the pilot-computer interfaces, the lateral path processor, and guidance and steering function are described.

Physically-based distributed hydrologic modeling of tropical catchments: Hypothesis testing on model formation and runoff generation

NASA Astrophysics Data System (ADS)

Abebe, N. A.; Ogden, F. L.

2011-12-01

Watersheds vary in their nature based on their geographic location, altitude, climate, geology, soils, and land use/land cover. These variations lead to differences in the conceptualization and formulation of hydrological models intended to represent the expected hydrological processes in a given catchment. Watersheds in the tropics are characterized by intensive and persistent biological activity and a large amount of rainfall. Our study focuses on the Agua Salud project catchments located in the Panama Canal Watershed, Panama, which have steep rolling topography, deep soils derived from weathered bedrock, and limited exposed bedrock. These catchments are also highly affected by soil cracks, decayed tree roots and animal burrows that form a network of preferential flow paths. One hypothesis is that these macropores conduct interflow during heavy rainfall, when a transient perched water table forms at a depth where the vertical hydraulic conductivity is significantly reduced near the bottom of the bioturbation layer. We have developed a physics-based, spatially distributed, multi-layered hydrologic model to simulate the dominant flow processes, including overland flow, channel flow, vertical matrix and non-Richards film flow, lateral downslope saturated matrix and non-Darcian pipe flow in the bioturbation layer and deep saturated groundwater flow. In our model formulation, we use the model to examine a variety of hydrological processes which we anticipate may occur. Emphasis is given to the modeling of the soil moisture dynamics in the bioturbation layer, development of lateral preferential flow and activation of the macropores and exchange of water at the interface between a bioturbation layer and a second layer below it. We consider interactions between surface water, ground water, channel water and perched water in the riparian zone cells with the aim of understanding likely runoff generation mechanisms. Results show that inclusion of as many different flow processes as possible during conceptualization and during model development helps to reject infeasible scenarios/hypotheses, and suggests further watershed-scale studies to improve our understanding of the hydrologic behavior of these poorly understood catchments.

Paper-based enzymatic microfluidic fuel cell: From a two-stream flow device to a single-stream lateral flow strip

NASA Astrophysics Data System (ADS)

González-Guerrero, Maria José; del Campo, F. Javier; Esquivel, Juan Pablo; Giroud, Fabien; Minteer, Shelley D.; Sabaté, Neus

2016-09-01

This work presents a first approach towards the development of a cost-effective enzymatic paper-based glucose/O2 microfluidic fuel cell in which fluid transport is based on capillary action. A first fuel cell configuration consists of a Y-shaped paper device with the fuel and the oxidant flowing in parallel over carbon paper electrodes modified with bioelectrocatalytic enzymes. The anode consists of a ferrocenium-based polyethyleneimine polymer linked to glucose oxidase (GOx/Fc-C6-LPEI), while the cathode contains a mixture of laccase, anthracene-modified multiwall carbon nanotubes, and tetrabutylammonium bromide-modified Nafion (MWCNTs/laccase/TBAB-Nafion). Subsequently, the Y-shaped configuration is improved to use a single solution containing both, the anolyte and the catholyte. Thus, the electrolytes pHs of the fuel and the oxidant solutions are adapted to an intermediate pH of 5.5. Finally, the fuel cell is run with this single solution obtaining a maximum open circuit of 0.55 ± 0.04 V and a maximum current and power density of 225 ± 17 μA cm-2 and 24 ± 5 μW cm-2, respectively. Hence, a power source closer to a commercial application (similar to conventional lateral flow test strips) is developed and successfully operated. This system can be used to supply the energy required to power microelectronics demanding low power consumption.

On-site detection of stacked genetically modified soybean based on event-specific TM-LAMP and a DNAzyme-lateral flow biosensor.

PubMed

Cheng, Nan; Shang, Ying; Xu, Yuancong; Zhang, Li; Luo, Yunbo; Huang, Kunlun; Xu, Wentao

2017-05-15

Stacked genetically modified organisms (GMO) are becoming popular for their enhanced production efficiency and improved functional properties, and on-site detection of stacked GMO is an urgent challenge to be solved. In this study, we developed a cascade system combining event-specific tag-labeled multiplex LAMP with a DNAzyme-lateral flow biosensor for reliable detection of stacked events (DP305423× GTS 40-3-2). Three primer sets, both event-specific and soybean species-specific, were newly designed for the tag-labeled multiplex LAMP system. A trident-like lateral flow biosensor displayed amplified products simultaneously without cross contamination, and DNAzyme enhancement improved the sensitivity effectively. After optimization, the limit of detection was approximately 0.1% (w/w) for stacked GM soybean, which is sensitive enough to detect genetically modified content up to a threshold value established by several countries for regulatory compliance. The entire detection process could be shortened to 120min without any large-scale instrumentation. This method may be useful for the in-field detection of DP305423× GTS 40-3-2 soybean on a single kernel basis and on-site screening tests of stacked GM soybean lines and individual parent GM soybean lines in highly processed foods. Copyright © 2017 Elsevier B.V. All rights reserved.

Rapid and Sensitive Detection of Protein Biomarker Using a Portable Fluorescence Biosensor based on Quantum Dots and a Lateral Flow Test Strip

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zhaohui; Wang, Ying; Wang, Jun

2010-08-15

A portable fluorescence biosensor with rapid and ultrasensitive response for trace protein has been built up with quantum dots and lateral flow test strip. The superior signal brightness and high photostability of quantum dots are combined with the promising advantages of lateral flow test strip and resulted in high sensitivity, selectivity and speedy for protein detection. Nitrated ceruloplasmin, a significant biomarker for cardiovascular disease, lung cancer and stress response to smoking, was used as model protein to demonstrate the good performances of this proposed Qdot-based lateral flow test strip. Quantitative detection of nitrated ceruloplasmin was realized by recording the fluorescencemore » intensity of quantum dots captured on the test line. Under optimal conditions, this portable fluorescence biosensor displays rapid responses for nitrated ceruloplasmin in wide dynamic range with a detection limit of 0.1ng/mL (S/N=3). Furthermore, the biosensor was successfully utilized for spiked human plasma sample detection with the concentration as low as 1ng/mL. The results demonstrate that the quantum dot-based lateral flow test strip is capable for rapid, sensitive, and quantitative detection of nitrated ceruloplasmin and hold a great promise for point-of-care and in field analysis of other protein biomarkers.« less

A Zebrafish Loss-of-Function Model for Human CFAP53 Mutations Reveals Its Specific Role in Laterality Organ Function.

PubMed

Noël, Emily S; Momenah, Tarek S; Al-Dagriri, Khalid; Al-Suwaid, Abdulrahman; Al-Shahrani, Safar; Jiang, Hui; Willekers, Sven; Oostveen, Yara Y; Chocron, Sonja; Postma, Alex V; Bhuiyan, Zahurul A; Bakkers, Jeroen

2016-02-01

Establishing correct left-right asymmetry during embryonic development is crucial for proper asymmetric positioning of the organs. Congenital heart defects, such as dextrocardia, transposition of the arteries, and inflow or outflow tract malformations, comprise some of the most common birth defects and may be attributed to incorrect establishment of body laterality. Here, we identify new patients with dextrocardia who have mutations in CFAP53, a coiled-coil domain containing protein. To elucidate the mechanism by which CFAP53 regulates embryonic asymmetry, we used genome editing to generate cfap53 zebrafish mutants. Zebrafish cfap53 mutants have specific defects in organ laterality and randomization of asymmetric gene expression. We show that cfap53 is required for cilia rotation specifically in Kupffer's vesicle, the zebrafish laterality organ, providing a mechanism by which patients with CFAP53 mutations develop dextrocardia and heterotaxy, and confirming previous evidence that left-right asymmetry in humans is regulated through cilia-driven fluid flow in a laterality organ. © 2015 WILEY PERIODICALS, INC.

Simulating Water Flow in Variably Saturated Soils - Exploring the Advantage of Three-dimensional Models

NASA Astrophysics Data System (ADS)

Hopp, L.; Ivanov, V. Y.

2010-12-01

There is still a debate in rainfall-runoff modeling over the advantage of using three-dimensional models based on partial differential equations describing variably saturated flow vs. models with simpler infiltration and flow routing algorithms. Fully explicit 3D models are computationally demanding but allow the representation of spatially complex domains, heterogeneous soils, conditions of ponded infiltration, and solute transport, among others. Models with simpler infiltration and flow routing algorithms provide faster run times and are likely to be more versatile in the treatment of extreme conditions such as soil drying but suffer from underlying assumptions and ad-hoc parameterizations. In this numerical study, we explore the question of whether these two model strategies are competing approaches or if they complement each other. As a 3D physics-based model we use HYDRUS-3D, a finite element model that numerically solves the Richards equation for variably-saturated water flow. As an example of a simpler model, we use tRIBS+VEGGIE that solves the 1D Richards equation for vertical flow and applies Dupuit-Forchheimer approximation for saturated lateral exchange and gravity-driven flow for unsaturated lateral exchange. The flow can be routed using either the D-8 (steepest descent) or D-infinity flow routing algorithms. We study lateral subsurface stormflow and moisture dynamics at the hillslope-scale, using a zero-order basin topography, as a function of storm size, antecedent moisture conditions and slope angle. The domain and soil characteristics are representative of a forested hillslope with conductive soils in a humid environment, where the major runoff generating process is lateral subsurface stormflow. We compare spatially integrated lateral subsurface flow at the downslope boundary as well as spatial patterns of soil moisture. We illustrate situations where both model approaches perform equally well and identify conditions under which the application of a fully-explicit 3D model may be required for a realistic description of the hydrologic response.

Newer concepts in the pathophysiology of ischemic heart disease.

PubMed

Kirk, E S; Factor, S; Sonnenblick, E H

1984-11-01

Thus the thrust of these studies suggests that blood flow is the overwhelming factor in determining the consequences of the imbalance of oxygen supply and demand. Moreover, the factors that determine the requirements for tissue survival in the presence of deep ischemia are not the same as those shown for the normal myocardium in figure 1. In deep ischemia, contraction ceases, and metabolism shifts from aerobic to anaerobic pathways. Survival rather than contractile function then becomes the agenda. Not only does supply tend to overshadow demand in determining extent of transmural necrosis, but the anatomical pattern of supply precisely delineates the region at risk following a coronary occlusion as well as the ultimate extent of infarction. These views are summarized in the model presented in figures 12 and 13. The anatomic distribution of the ligated artery determines the lateral limits of the ischemic region (Fig. 12) and thus the lateral extension of necrosis (Fig. 13). The extension of the necrosis across the heart wall depends largely on the status of perfusion within the ischemic region. Extension of an infarct, should it occur, has to be explained by other mechanisms. These might include: (i) vascular obstruction in adjacent vascular systems that were not involved in the first occlusion, (ii) relative ischemia in the normal tissue surrounding the ischemic tissue due to an increased wall stress at the demarcation between contracting and noncontracting tissue, or (9) interruption of vessels supplying large interdigitations of normal tissue within the originally ischemic tissue due to changes associated with the process of infarction of ischemia. Alternatively, much that is called extension of infarction may involve more of the wall transmurally without lateral extension. Additional features of the development of myocardial infarction in figures 12 and 13 include: (i) the development of collateral vessel function resulting in an increased capacity to supply the ischemic area, and (ii) a redistribution of collateral blood flow from necrotic to surviving myocardium within the ischemic area. Thus, as coronary collaterals develop, collateral blood flow becomes increasingly heterogeneous within the ischemic area. Following a coronary occlusion, blood flow is reduced more in the subendocardium, and infarction occurs. Resistance to flow in infarcting tissue increase and causes a redistribution of flow to adjacent surviving layers of myocardium that life toward the epicardium. The process continues and combined with the enlargement of collateral vessels results in a sufficient flow to the epicardial layers so that they may survive.

Flow structures and sandbar dynamics in a canyon river during a controlled flood, Colorado River, Arizona

USGS Publications Warehouse

Wright, S.A.; Kaplinski, M.

2011-01-01

In canyon rivers, debris fan constrictions create rapids and downstream pools characterized by secondary flow structures that are closely linked to channel morphology. In this paper we describe detailed measurements of the three-dimensional flow structure and sandbar dynamics of two pools along the Colorado River in the Grand Canyon during a controlled flood release from Glen Canyon Dam. Results indicate that the pools are characterized by large lateral recirculation zones (eddies) resulting from flow separation downstream from the channel constrictions, as well as helical flow structures in the main channel and eddy. The lateral recirculation zones are low-velocity areas conducive to fine sediment deposition, particularly in the vicinity of the separation and reattachment points and are thus the dominant flow structures controlling sandbar dynamics. The helical flow structures also affect morphology but appear secondary in importance to the lateral eddies. During the controlled flood, sandbars in the separation and reattachment zones at both sites tended to build gradually during the rising limb and peak flow. Deposition in shallow water on the sandbars was accompanied by erosion in deeper water along the sandbar slope at the interface with the main channel. Erosion occurred via rapid mass failures as well as by gradual boundary shear stress driven processes. The flow structures and morphologic links at our study sites are similar to those identified in other river environments, in particular sharply curved meanders and channel confluences where the coexistence of lateral recirculation and helical flows has been documented. Copyright 2011 by the American Geophysical Union.

Imaging lateral groundwater flow in the shallow subsurface using stochastic temperature fields

NASA Astrophysics Data System (ADS)

Fairley, Jerry P.; Nicholson, Kirsten N.

2006-04-01

Although temperature has often been used as an indication of vertical groundwater movement, its usefulness for identifying horizontal fluid flow has been limited by the difficulty of obtaining sufficient data to draw defensible conclusions. Here we use stochastic simulation to develop a high-resolution image of fluid temperatures in the shallow subsurface at Borax Lake, Oregon. The temperature field inferred from the geostatistical simulations clearly shows geothermal fluids discharging from a group of fault-controlled hydrothermal springs, moving laterally through the subsurface, and mixing with shallow subsurface flow originating from nearby Borax Lake. This interpretation of the data is supported by independent geochemical and isotopic evidence, which show a simple mixing trend between Borax Lake water and discharge from the thermal springs. It is generally agreed that stochastic simulation can be a useful tool for extracting information from complex and/or noisy data and, although not appropriate in all situations, geostatistical analysis may provide good definition of flow paths in the shallow subsurface. Although stochastic imaging techniques are well known in problems involving transport of species, e.g. delineation of contaminant plumes from soil gas survey data, we are unaware of previous applications to the transport of thermal energy for the purpose of inferring shallow groundwater flow.

Assessment of analytical methods to determine pyrethroids content of bednets.

PubMed

Castellarnau, Marc; Ramón-Azcón, Javier; Gonzalez-Quinteiro, Yolanda; López, Jordi F; Grimalt, Joan O; Marco, María-Pilar; Nieuwenhuijsen, Mark; Picado, Albert

2017-01-01

To present and evaluate simple, cost-effective tests to determine the amount of insecticide on treated materials. We developed and evaluated a competitive immunoassay on two different platforms: a label-free impedimetric biosensor (EIS biosensor) and a lateral flow. Both approaches were validated by gas chromatography (GC) and ELISA, gold standards for analytical methods and immunoassays, respectively. Finally, commercially available pyrethroid-treated ITN samples were analysed. Different extraction methods were evaluated. Insecticide extraction by direct infusion of the ITN samples with dichloromethane and dioxane showed recovery efficiencies around 100% for insecticide-coated bednets, and >70% for insecticide-incorporated bednets. These results were comparable to those obtained with standard sonication methods. The competitive immunoassay characterisation with ELISA presented a dynamic range between 12 nm and 1.5 μm (coefficient of variation (CV) below 5%), with an IC 50 at 138 nm, and a limit of detection (LOD) of 3.2 nm. EIS biosensor had a linear range between 1.7 nm and 61 nm (CV around 14%), with an IC 50 at 10.4 nm, and a LOD of 0.6 nm. Finally, the lateral flow approach showed a dynamic range between 150 nm and 1.5 μm, an IC 50 at 505 nm and a LOD of 67 nm. ELISA can replace chromatography as an accurate laboratory technique to determine insecticide concentration in bednets. The lateral flow approach developed can be used to estimate ITN insecticide concentration in the field. This new technology, coupled to the new extraction methods, should provide reliable guidelines for ITN use and replacement in the field. © 2016 John Wiley & Sons Ltd.

Development of a recombinase polymerase amplification combined with lateral-flow dipstick assay for detection of bovine ephemeral fever virus.

PubMed

Hou, Peili; Zhao, Guimin; Wang, Hongmei; He, Chengqiang; Huan, Yanjun; He, Hongbin

2018-04-01

Bovine ephemeral fever virus (BEFV), identified as the causative pathogen of bovine ephemeral fever (BEF), is responsible for increasing numbers of epidemics/outbreaks and has a significant harmful effect on the livestock industry. Therefore, a rapid detection assay is imperative for BEFV diagnosis. In this study, we described the development of lateral-flow dipstick isothermal recombinase polymerase amplification (LFD-RPA) assays for detection of BEFV. RPA primers and LF probes were designed by targeting the specific G gene, and the amplification product can be visualized on a simple lateral flow dipstick with the naked eyes. The amplification reaction was performed at 38 °C for 20 min and LFD incubation time within 5 min. The detection limit of this assay was 8 copies per reaction, and there was no cross-reactivity with other bovine infectious viruses such as bovine viral diarrhea virus, infectious bovine rhinotracheitis virus, bovine respiratory syncytial virus, bovine coronavirus, bovine parainfluenza virus type 3, bovine vesicular stomatitis virus. In addition, the assay was performed with total 128 clinical specimens and the diagnostic results were compared with conventional RT-PCR, real-time quantative(q) PCR. The result showed that the coincidence rate of BEFV LFD-RPA and real-time qPCR was 96.09% (123/128), which was higher than conventional RT-PCR. The RPA combined with LFD assay probably provides a rapid and sensitive alternative for diagnosis of BEFV infections outbreak. Copyright © 2018 Elsevier Ltd. All rights reserved.

Acute Effects of Lateral Thigh Foam Rolling on Arterial Tissue Perfusion Determined by Spectral Doppler and Power Doppler Ultrasound.

PubMed

Hotfiel, Thilo; Swoboda, Bernd; Krinner, Sebastian; Grim, Casper; Engelhardt, Martin; Uder, Michael; Heiss, Rafael U

2017-04-01

Hotfiel, T, Swoboda, B, Krinner, S, Grim, C, Engelhardt, M, Uder, M, and Heiss, R. Acute effects of lateral thigh foam rolling on arterial tissue perfusion determined by spectral Doppler and power Doppler ultrasound. J Strength Cond Res 31(4): 893-900, 2017-Foam rolling has been developed as a popular intervention in training and rehabilitation. However, evidence on its effects on the cellular and physiological level is lacking. The aim of this study was to assess the effect of foam rolling on arterial blood flow of the lateral thigh. Twenty-one healthy participants (age, 25 ± 2 years; height, 177 ± 9 cm; body weight, 74 ± 9 kg) were recruited from the medical and sports faculty. Arterial tissue perfusion was determined by spectral Doppler and power Doppler ultrasound, represented as peak flow (Vmax), time average velocity maximum (TAMx), time average velocity mean (TAMn), and resistive index (RI), and with semiquantitative grading that was assessed by 4 blindfolded investigators. Measurement values were assessed under resting conditions and twice after foam rolling exercises of the lateral thigh (0 and 30 minutes after intervention). The trochanteric region, mid portion, and distal tibial insertion of the lateral thigh were representative for data analysis. Arterial blood flow of the lateral thigh increased significantly after foam rolling exercises compared with baseline (p ≤ 0.05). We detected a relative increase in Vmax of 73.6% (0 minutes) and 52.7% (30 minutes) (p < 0.001), in TAMx of 53.2% (p < 0.001) and 38.3% (p = 0.002), and in TAMn of 84.4% (p < 0.001) and 68.2% (p < 0.001). Semiquantitative power Doppler scores at all portions revealed increased average grading of 1.96 after intervention and 2.04 after 30 minutes compared with 0.75 at baseline. Our results may contribute to the understanding of local physiological reactions to self-myofascial release.

Flow patterns and bathymetric signatures on the delta front of a prograding river delta

NASA Astrophysics Data System (ADS)

Shaw, J.; Mohrig, D. C.; Wagner, R. W.

2016-02-01

The transition of water between laterally confined channels and the unchannelized delta front controls the growth pattern of river deltas, but is difficult to measure on field-scale deltas. We quantify flow patterns, bathymetry and bathymetric evolution for the subaqueous delta front on the Wax Lake Delta (WLD), a rapidly prograding delta in coastal Louisiana. The flow direction field, mapped using streaklines composed of biogenic slicks on the water surface, shows that a significant portion of flow ( 59%) departs subaqueous channels laterally over the subaqueous margins of the channel seaward of the shoreline. Synoptic datasets of bathymetry and flow direction allow spatial changes in flow velocity to be quantified. Most lateral flow divergence and deceleration occurs within 3-8 channel widths outboard of subaqueous channel margins, rather than downstream of channel tips. In interdistributary bays, deposit elevation decreases with a basinward slope of 2.4 x 10-4 with distance from a channel margin along any flow path. Flow patterns and this slope produce constructional features called interdistributary troughs - topographic lows in the center of interdistributary bays. These data show that flow patterns and bathymetry on the delta front are coupled both at the transition from channelized to unchannelized flow and in the depositional regions outside the distributary network.

A novel 3D micron-scale DPTV (Defocused Particle Tracking Velocimetry) and its applications in microfluidic devices

NASA Astrophysics Data System (ADS)

Roberts, John

2005-11-01

The rapid advancements in micro/nano biotechnology demand quantitative tools for characterizing microfluidic flows in lab-on-a-chip applications, validation of computational results for fully 3D flows in complex micro-devices, and efficient observation of cellular dynamics in 3D. We present a novel 3D micron-scale DPTV (defocused particle tracking velocimetry) that is capable of mapping out 3D Lagrangian, as well as 3D Eulerian velocity flow fields at sub-micron resolution and with one camera. The main part of the imaging system is an epi-fluorescent microscope (Olympus IX 51), and the seeding particles are fluorescent particles with diameter range 300nm - 10um. A software package has been developed for identifying (x,y,z,t) coordinates of the particles using the defocused images. Using the imaging system, we successfully mapped the pressure driven flow fields in microfluidic channels. In particular, we measured the Laglangian flow fields in a microfluidic channel with a herring bone pattern at the bottom, the later is used to enhance fluid mixing in lateral directions. The 3D particle tracks revealed the flow structure that has only been seen in numerical computation. This work is supported by the National Science Foundation (CTS - 0514443), the Nanobiotechnology Center at Cornell, and The New York State Center for Life Science Enterprise.

Numerical determination of lateral loss coefficients for subchannel analysis in nuclear fuel bundles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sin Kim; Goon-Cherl Park

1995-09-01

An accurate prediction of cross-flow based on detailed knowledge of the velocity field in subchannels of a nuclear fuel assembly is of importance in nuclear fuel performance analysis. In this study, the low-Reynolds number {kappa}-{epsilon} turbulence model has been adopted in two adjacent subchannels with cross-flow. The secondary flow is estimated accurately by the anisotropic algebraic Reynolds stress model. This model was numerically calculated by the finite element method and has been verified successfully through comparison with existing experimental data. Finally, with the numerical analysis of the velocity field in such subchannel domain, an analytical correlation of the lateral lossmore » coefficient is obtained to predict the cross-flow rate in subchannel analysis codes. The correlation is expressed as a function of the ratio of the lateral flow velocity to the donor subchannel axial velocity, recipient channel Reynolds number and pitch-to-diameter.« less

Automated Low-Cost Smartphone-Based Lateral Flow Saliva Test Reader for Drugs-of-Abuse Detection.

PubMed

Carrio, Adrian; Sampedro, Carlos; Sanchez-Lopez, Jose Luis; Pimienta, Miguel; Campoy, Pascual

2015-11-24

Lateral flow assay tests are nowadays becoming powerful, low-cost diagnostic tools. Obtaining a result is usually subject to visual interpretation of colored areas on the test by a human operator, introducing subjectivity and the possibility of errors in the extraction of the results. While automated test readers providing a result-consistent solution are widely available, they usually lack portability. In this paper, we present a smartphone-based automated reader for drug-of-abuse lateral flow assay tests, consisting of an inexpensive light box and a smartphone device. Test images captured with the smartphone camera are processed in the device using computer vision and machine learning techniques to perform automatic extraction of the results. A deep validation of the system has been carried out showing the high accuracy of the system. The proposed approach, applicable to any line-based or color-based lateral flow test in the market, effectively reduces the manufacturing costs of the reader and makes it portable and massively available while providing accurate, reliable results.

Twin tubular pinch effect in curving confined flows

PubMed Central

Clime, Liviu; Morton, Keith J.; Hoa, Xuyen D.; Veres, Teodor

2015-01-01

Colloidal suspensions of buoyancy neutral particles flowing in circular pipes focus into narrow distributions near the wall due to lateral migration effects associated with fluid inertia. In curving flows, these distributions are altered by Dean currents and the interplay between Reynolds and Dean numbers is used to predict equilibrium positions. Here, we propose a new description of inertial lateral migration in curving flows that expands current understanding of both focusing dynamics and equilibrium distributions. We find that at low Reynolds numbers, the ratio δ between lateral inertial migration and Dean forces scales simply with the particle radius, coil curvature and pipe radius as . A critical value δc = 0.148 of this parameter is identified along with two related inertial focusing mechanisms. In the regime below δc, coined subcritical, Dean forces generate permanently circulating, twinned annuli, each with intricate equilibrium particle distributions including eyes and trailing arms. At δ > δc (supercritical regime) inertial lateral migration forces are dominant and particles focus to a single stable equilibrium position. PMID:25927878

Incorporating seismic observations into 2D conduit flow modeling

NASA Astrophysics Data System (ADS)

Collier, L.; Neuberg, J.

2006-04-01

Conduit flow modeling aims to understand the conditions of magma at depth, and to provide insight into the physical processes that occur inside the volcano. Low-frequency events, characteristic to many volcanoes, are thought to contain information on the state of magma at depth. Therefore, by incorporating information from low-frequency seismic analysis into conduit flow modeling a greater understanding of magma ascent and its interdependence on magma conditions and physical processes is possible. The 2D conduit flow model developed in this study demonstrates the importance of lateral pressure and parameter variations on overall magma flow dynamics, and the substantial effect bubbles have on magma shear viscosity and on magma ascent. The 2D nature of the conduit flow model developed here allows in depth investigation into processes which occur at, or close to the wall, such as magma cooling and brittle failure of melt. These processes are shown to have a significant effect on magma properties and therefore, on flow dynamics. By incorporating low-frequency seismic information, an advanced conduit flow model is developed including the consequences of brittle failure of melt, namely friction-controlled slip and gas loss. This model focuses on the properties and behaviour of magma at depth within the volcano, and their interaction with the formation of seismic events by brittle failure of melt.

LATERAL HEAT FLOW INFRARED THERMOGRAPHY FOR THICKNESS INDEPENDENT DETERMINATION OF THERMAL DIFFUSIVITY IN CFRP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tralshawala, Nilesh; Howard, Don; Knight, Bryon

2008-02-28

In conventional infrared thermography, determination of thermal diffusivity requires thickness information. Recently GE has been experimenting with the use of lateral heat flow to determine thermal diffusivity without thickness information. This work builds on previous work at NASA Langley and Wayne State University but we incorporate thermal time of flight (tof) analysis rather than curve fitting to obtain quantitative information. We have developed appropriate theoretical models and a tof based data analysis framework to experimentally determine all components of thermal diffusivity from the time-temperature measurements. Initial validation was carried out using finite difference simulations. Experimental validation was done using anisotropicmore » carbon fiber reinforced polymer (CFRP) composites. We found that in the CFRP samples used, the in-plane component of diffusivity is about eight times larger than the through-thickness component.« less

Percutaneous Sclerotherapy of Congenital Slow-Flow Vascular Malformations of the Orbit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiramel, George Koshy, E-mail: gkchiramel@gmail.com; Keshava, Shyamkumar Nidugala, E-mail: aparna-shyam@yahoo.com; Moses, Vinu, E-mail: vinu@cmcvellore.ac.in

PurposeThis manuscript describes the clinical features, imaging findings, treatment details, and short-term outcomes of a series of congenital slow-flow vascular malformations.MethodsThis was a prospective study of congenital slow-flow vascular malformations involving the orbital region treated at a single institution with percutaneous sclerotherapy.ResultsTen patients presented during the study period, comprising eight venous malformations, one lymphatic malformation, and one veno-lymphatic malformation. Nine patients underwent percutaneous sclerotherapy under digital subtraction angiography guidance, of which three developed marked rise in intraocular pressure requiring lateral canthotomy. The treatments were performed in the presence of an ophthalmologist who measured the intraorbital pressure during and after the procedure. Onmore » follow-up, some of the patients required repeat sessions of sclerotherapy. All patients had improvement of symptoms on follow up after the procedure.ConclusionCongenital slow-flow vascular malformations of the orbital region are rare lesions that should be treated using a multidisciplinary approach. Monitoring of the intraorbital pressure is required both during and after the procedure to decide about the need for lateral canthotomy to reduce the transiently increased intraorbital pressure.« less

Developing Interpretive Turbulence Models from a Database with Applications to Wind Farms and Shipboard Operations

NASA Astrophysics Data System (ADS)

Schau, Kyle A.

This thesis presents a complete method of modeling the autospectra of turbulence in closed form via an expansion series using the von Karman model as a basis function. It is capable of modeling turbulence in all three directions of fluid flow: longitudinal, lateral, and vertical, separately, thus eliminating the assumption of homogeneous, isotropic flow. A thorough investigation into the expansion series is presented, with the strengths and weaknesses highlighted. Furthermore, numerical aspects and theoretical derivations are provided. This method is then tested against three highly complex flow fields: wake turbulence inside wind farms, helicopter downwash, and helicopter downwash coupled with turbulence shed from a ship superstructure. These applications demonstrate that this method is remarkably robust, that the developed autospectral models are virtually tailored to the design of white noise driven shaping filters, and that these models in closed form facilitate a greater understanding of complex flow fields in wind engineering.

Bootstrapping the energy flow in the beginning of life.

PubMed

Hengeveld, R; Fedonkin, M A

2007-01-01

This paper suggests that the energy flow on which all living structures depend only started up slowly, the low-energy, initial phase starting up a second, slightly more energetic phase, and so on. In this way, the build up of the energy flow follows a bootstrapping process similar to that found in the development of computers, the first generation making possible the calculations necessary for constructing the second one, etc. In the biogenetic upstart of an energy flow, non-metals in the lower periods of the Periodic Table of Elements would have constituted the most primitive systems, their operation being enhanced and later supplanted by elements in the higher periods that demand more energy. This bootstrapping process would put the development of the metabolisms based on the second period elements carbon, nitrogen and oxygen at the end of the evolutionary process rather than at, or even before, the biogenetic event.

Determination of real-time predictors of the wind turbine wake meandering

NASA Astrophysics Data System (ADS)

Muller, Yann-Aël; Aubrun, Sandrine; Masson, Christian

2015-03-01

The present work proposes an experimental methodology to characterize the unsteady properties of a wind turbine wake, called meandering, and particularly its ability to follow the large-scale motions induced by large turbulent eddies contained in the approach flow. The measurements were made in an atmospheric boundary layer wind tunnel. The wind turbine model is based on the actuator disc concept. One part of the work has been dedicated to the development of a methodology for horizontal wake tracking by mean of a transverse hot wire rake, whose dynamic response is adequate for spectral analysis. Spectral coherence analysis shows that the horizontal position of the wake correlates well with the upstream transverse velocity, especially for wavelength larger than three times the diameter of the disc but less so for smaller scales. Therefore, it is concluded that the wake is actually a rather passive tracer of the large surrounding turbulent structures. The influence of the rotor size and downstream distance on the wake meandering is studied. The fluctuations of the lateral force and the yawing torque affecting the wind turbine model are also measured and correlated with the wake meandering. Two approach flow configurations are then tested: an undisturbed incoming flow (modelled atmospheric boundary layer) and a disturbed incoming flow, with a wind turbine model located upstream. Results showed that the meandering process is amplified by the presence of the upstream wake. It is shown that the coherence between the lateral force fluctuations and the horizontal wake position is significant up to length scales larger than twice the wind turbine model diameter. This leads to the conclusion that the lateral force is a better candidate than the upstream transverse velocity to predict in real time the meandering process, for either undisturbed (wake free) or disturbed incoming atmospheric flows.

Simulation and validation of concentrated subsurface lateral flow paths in an agricultural landscape

NASA Astrophysics Data System (ADS)

Zhu, Q.; Lin, H. S.

2009-08-01

The importance of soil water flow paths to the transport of nutrients and contaminants has long been recognized. However, effective means of detecting concentrated subsurface flow paths in a large landscape are still lacking. The flow direction and accumulation algorithm based on single-direction flow algorithm (D8) in GIS hydrologic modeling is a cost-effective way to simulate potential concentrated flow paths over a large area once relevant data are collected. This study tested the D8 algorithm for simulating concentrated lateral flow paths at three interfaces in soil profiles in a 19.5-ha agricultural landscape in central Pennsylvania, USA. These interfaces were (1) the interface between surface plowed layers of Ap1 and Ap2 horizons, (2) the interface with subsoil water-restricting clay layer where clay content increased to over 40%, and (3) the soil-bedrock interface. The simulated flow paths were validated through soil hydrologic monitoring, geophysical surveys, and observable soil morphological features. The results confirmed that concentrated subsurface lateral flow occurred at the interfaces with the clay layer and the underlying bedrock. At these two interfaces, the soils on the simulated flow paths were closer to saturation and showed more temporally unstable moisture dynamics than those off the simulated flow paths. Apparent electrical conductivity in the soil on the simulated flow paths was elevated and temporally unstable as compared to those outside the simulated paths. The soil cores collected from the simulated flow paths showed significantly higher Mn content at these interfaces than those away from the simulated paths. These results suggest that (1) the D8 algorithm is useful in simulating possible concentrated subsurface lateral flow paths if used with appropriate threshold value of contributing area and sufficiently detailed digital elevation model (DEM); (2) repeated electromagnetic surveys can reflect the temporal change of soil water storage and thus is a useful indicator of possible subsurface flow path over a large area; and (3) observable Mn distribution in soil profiles can be used as a simple indicator of water flow paths in soils and over the landscape; however, it does require sufficient soil sampling (by excavation or augering) to possibly infer landscape-scale subsurface flow paths. In areas where subsurface interface topography varies similarly with surface topography, surface DEM can be used to simulate potential subsurface lateral flow path reasonably so the cost associated with obtaining depth to subsurface water-restricting layer can be minimized.

Assessing lateral flows and solute transport during floods in a conduit-flow-dominated karst system using the inverse problem for the advection-diffusion equation

NASA Astrophysics Data System (ADS)

Cholet, Cybèle; Charlier, Jean-Baptiste; Moussa, Roger; Steinmann, Marc; Denimal, Sophie

2017-07-01

The aim of this study is to present a framework that provides new ways to characterize the spatio-temporal variability of lateral exchanges for water flow and solute transport in a karst conduit network during flood events, treating both the diffusive wave equation and the advection-diffusion equation with the same mathematical approach, assuming uniform lateral flow and solute transport. A solution to the inverse problem for the advection-diffusion equations is then applied to data from two successive gauging stations to simulate flows and solute exchange dynamics after recharge. The study site is the karst conduit network of the Fourbanne aquifer in the French Jura Mountains, which includes two reaches characterizing the network from sinkhole to cave stream to the spring. The model is applied, after separation of the base from the flood components, on discharge and total dissolved solids (TDSs) in order to assess lateral flows and solute concentrations and compare them to help identify water origin. The results showed various lateral contributions in space - between the two reaches located in the unsaturated zone (R1), and in the zone that is both unsaturated and saturated (R2) - as well as in time, according to hydrological conditions. Globally, the two reaches show a distinct response to flood routing, with important lateral inflows on R1 and large outflows on R2. By combining these results with solute exchanges and the analysis of flood routing parameters distribution, we showed that lateral inflows on R1 are the addition of diffuse infiltration (observed whatever the hydrological conditions) and localized infiltration in the secondary conduit network (tributaries) in the unsaturated zone, except in extreme dry periods. On R2, despite inflows on the base component, lateral outflows are observed during floods. This pattern was attributed to the concept of reversal flows of conduit-matrix exchanges, inducing a complex water mixing effect in the saturated zone. From our results we build the functional scheme of the karst system. It demonstrates the impact of the saturated zone on matrix-conduit exchanges in this shallow phreatic aquifer and highlights the important role of the unsaturated zone on storage and transfer functions of the system.

A Muskingum-based methodology for river discharge estimation and rating curve development under significant lateral inflow conditions

NASA Astrophysics Data System (ADS)

Barbetta, Silvia; Moramarco, Tommaso; Perumal, Muthiah

2017-11-01

Quite often the discharge at a site is estimated using the rating curve developed for that site and its development requires river flow measurements, which are costly, tedious and dangerous during severe floods. To circumvent the conventional rating curve development approach, Perumal et al. in 2007 and 2010 applied the Variable Parameter Muskingum Stage-hydrograph (VPMS) routing method for developing stage-discharge relationships especially at those ungauged river sites where stage measurements and details of section geometry are available, but discharge measurements are not made. The VPMS method enables to estimate rating curves at ungauged river sites with acceptable accuracy. But the application of the method is subjected to the limitation of negligible presence of lateral flow within the routing reach. To overcome this limitation, this study proposes an extension of the VPMS method, henceforth, known herein as the VPMS-Lin method, for enabling the streamflow assessment even when significant lateral inflow occurs along the river reach considered for routing. The lateral inflow is estimated through the continuity equation expressed in the characteristic form as advocated by Barbetta et al. in 2012. The VPMS-Lin, is tested on two rivers characterized by different geometric and hydraulic properties: 1) a 50 km reach of the Tiber River in (central Italy) and 2) a 73 km reach of the Godavari River in the peninsular India. The study demonstrates that both the upstream and downstream discharge hydrographs are well reproduced, with a root mean square error equal on average to about 35 and 1700 m3 s-1 for the Tiber River and the Godavari River case studies, respectively. Moreover, simulation studies carried out on a river stretch of the Tiber River using the one-dimensional hydraulic model MIKE11 and the VPMS-Lin models demonstrate the accuracy of the VMPS-Lin model, which besides enabling the estimation of streamflow, also enables the estimation of reach averaged optimal roughness coefficients for the considered routing events.

Does the Alpha-defensin Immunoassay or the Lateral Flow Test Have Better Diagnostic Value for Periprosthetic Joint Infection? A Systematic Review.

PubMed

Eriksson, Hannah K; Nordström, Jakob; Gabrysch, Katja; Hailer, Nils P; Lazarinis, Stergios

2018-05-01

Measuring alpha-defensin concentrations in synovial fluid may help to diagnose periprosthetic joint infection (PJI). There are two commercially available methods for measuring alpha-defensin in synovial fluid: the enzyme-linked immunosorbent assay-based Synovasure® alpha-defensin immunoassay, which gives a numeric readout within 24 hours, and the Synovasure lateral flow test, which gives a binary readout within 20 minutes. There is no compilation of the existing literature to support the use of one of these two tests over the other. Does the immunoassay or the lateral flow test have better diagnostic value (sensitivity and specificity) in diagnosing PJI? We followed PRISMA guidelines and identified all studies on alpha-defensin concentration in synovial fluid as a PJI diagnostic marker, indexed to April 14, 2017, in PubMed, JSTOR, Google Scholar, and OVID databases. The search retrieved 1578 records. All prospective and retrospective studies on alpha-defensin as a PJI marker (PJI classified according to the criteria of the Musculoskeletal Infection Society) after THA or TKA were included in the analysis. All studies used only one of the two commercially available test methods, but none of them was comparative. After excluding studies with overlapping patient populations, four studies investigating the alpha-defensin immunoassay and three investigating the lateral flow test remained. Alpha-defensin immunoassay studies included 482 joints and lateral flow test studies included 119. The quality of the trials was assessed according to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. The heterogeneity among studies was evaluated by the I index, indicating that the heterogeneity of the included studies was low. Pooled sensitivity, specificity, positive and negative likelihood ratios, and receiver operating curves were calculated for each method and compared with each other. The alpha-defensin immunoassay had superior overall diagnostic value compared with the lateral flow test (area under the curve, 0.98 versus 0.75) with higher sensitivity (96% [90%-98%] versus 71% [55%-83%], p < 0.001), but no difference in specificity with the numbers available (96% [93%-97%] versus 90% [81%-95%], p = 0.060). Measurement of alpha-defensin in synovial fluid is a valuable complement to existing diagnostic criteria, and the immunoassay test detects PJI more accurately than the lateral flow test. The lateral flow test has lower sensitivity, making it difficult to rule out infection, but its relatively high specificity combined with the advantage of a quick response time can make it useful to rule in infection perioperatively. Level III, diagnostic study.

Sedentary behavior as a factor in determining lateral line contributions to rheotaxis.

PubMed

Bak-Coleman, Joseph; Coombs, Sheryl

2014-07-01

Rheotaxis is a robust, multisensory behavior with many potential benefits for fish and other aquatic animals. Visual (optic flow) cues appear to be sufficient for rheotaxis, but other sensory cues can clearly compensate for the loss of vision. The role of various non-visual sensory systems, in particular the flow-sensing lateral line, is poorly understood, largely because of widely varying methods and sensory conditions for studying rheotaxis. Here, we examine how sedentary behavior under visually deprived conditions affects the relative importance of lateral line cues in two species: one that is normally sedentary (the three-lined corydoras, Corydoras trilineatus) and one that normally swims continuously along the substrate (the blind cavefish, Astyanax mexicanus). No effect of lateral line disruption on rheotactic performance was found in blind cavefish, which were significantly more mobile than three-lined corydoras. By contrast, rheotaxis was significantly impaired at low, but not high, flow speeds in lateral-line-disabled corydoras. In addition, lateral-line-enabled corydoras were characterized by decreased mobility and increased rheotactic performance relative to lateral-line-disabled fish. Taken together, these results suggest that sedentary behavior is an important factor in promoting reliance on lateral line cues. © 2014. Published by The Company of Biologists Ltd.

Developing a Mouse Model of Sensory and Cognitive Deficits for Multiple Sclerosis

DTIC Science & Technology

2013-07-01

the plot is essentially horizontal, indicating that these mutants cannot localize sounds in space. A well-known characteristic of signal flow ...the five characteristic peaks and troughs of the ABR arising from generators in the eighth cranial nerve, cochlear nucleus, SOC, lateral lemniscus and

Gravity-driven, dry granular flows over a loose bed in stationary and homogeneous conditions

NASA Astrophysics Data System (ADS)

Meninno, Sabrina; Armanini, Aronne; Larcher, Michele

2018-02-01

Flows involving solid particulates have been widely studied in recent years, but their dynamics are still a complex issue to model because they strongly depend on the interaction with the boundary conditions. We report on laboratory investigations regarding homogeneous and steady flows of identical particles over a loose bed in a rectangular channel. Accurate measurements were carried out through imaging techniques to estimate profiles of the mean velocity, solid concentration, and granular temperature for a large set of flow rates and widths. Vertical and transversal structures observed in the flow change as interparticle interactions become more collisional, and they depend on the bottom over which the flow develops. The lateral confinement has a remarkable effect on the flow, especially for narrow channels compared with the grain size, and a hydraulic analogy is able to show how the walls influence the mechanisms of friction and energy dissipation.

Development of a microfluidic device for simultaneous mixing and pumping

NASA Astrophysics Data System (ADS)

Kim, Byoung Jae; Yoon, Sang Youl; Lee, Kyung Heon; Sung, Hyung Jin

2009-01-01

We conducted experimental and numerical studies aimed at developing a microfluidic device capable of simultaneous mixing while pumping. The proposed multifunctional device makes use of alternating current electroosmotic flow and adopts an array of planar asymmetric microelectrodes with a diagonal or herringbone shape. The pumping performance was assessed in terms of the fluid velocity at the center of the microchannel, obtained by micro PIV. To assess the mixing, flow visualizations were carried out over the electrodes to verify the lateral flows. The mixing degree was quantified in terms of a mixing efficiency obtained by three-dimensional numerical simulations. The results showed that simultaneous mixing and pumping was achieved in the channels with diagonal or herringbone electrode configurations. A herringbone electrode configuration showed better pumping compared with a reference, as well as enhanced mixing.

Nonperiodic eddy pulsations

USGS Publications Warehouse

Rubin, David M.; McDonald, Richard R.

1995-01-01

Recirculating flow in lateral separation eddies is typically weaker than main stem flow and provides an effective environment for trapping sediment. Observations of recirculating flow and sedimentary structures demonstrate that eddies pulsate in size and in flow velocity even when main stem flow is steady. Time series measurements of flow velocity and location of the reattachment point indicate that these pulsations are nonperiodic. Nonperiodic flow in the lee of a channel margin constriction is grossly different from the periodic flow in the lee of a cylinder that is isolated in a flow. Our experiments demonstrate that placing a flow-parallel plate adjacent to a cylinder is sufficient to cause the leeside flow to change from a periodic sequence of vortices to a nonperiodically pulsating lateral separation eddy, even if flow conditions are otherwise unchanged. Two processes cause the leeside flow to become nonperiodic when the plate is added. First, vortices that are shed from the cylinder deform and become irregular as they impact the plate or interfere with remnants of other vortices near the reattachment point. Second, these deformed vortices and other flow structures are recirculated in the lateral separation eddy, thereby influencing the future state (pressure and momentum distribution) of the recirculating flow. The vortex deformation process was confirmed experimentally by documenting spatial differences in leeside flow; vortex shedding that is evident near the separation point is undetectable near the reattachment point. Nonlinear forecasting techniques were used in an attempt to distinguish among several possible kinds of nonperiodic flows. The computational techniques were unable to demonstrate that any of the nonperiodic flows result from low-dimensional nonlinear processes.

Slow-release Permanganate Gel (SRP-G) for Groundwater Remediation: Spreading, Gelation, and Release in Porous and Low-Permeability Media

NASA Astrophysics Data System (ADS)

Lee, E. S.; Hastings, J.; Kim, Y.

2015-12-01

Dense nonaqueous phase liquids (DNAPLs) like trichloroethylene (TCE) serve as the most common form of groundwater pollution in the world. Pore-plugging by the solid oxidation product MnO2 and limited lateral dispersion of the oxidant are two common problems with existing in-situ chemical oxidation (ISCO) schemes that could be alleviated through the development of a delayed gelation method for oxidant delivery. The objective of the current study was to further develop and optimize slow-release permanganate gel (SRP-G), a solution comprising colloidal silica and KMnO4, as a novel low-cost treatment option for large and dilute TCE plumes in groundwater. Batch tests showed that gelation could be delayed through manipulation of KMnO4 concentration, pH, and silica particle size of the SRP-G solution. In flow-through columns and flow-tanks filled with saturated sands, silica concentration had little effect on the gelation lag stage and release rate, but increasing silica concentration was associated with increasing release duration. When compared to a pure KMnO4 solution, visual observations and [MnO4-] measurements from flow tank tests demonstrated that the SRP-G prolonged the release duration and enhanced lateral spreading of the oxidant.

Interfacing the Generalized Fluid System Simulation Program with the SINDA/G Thermal Program

NASA Technical Reports Server (NTRS)

Schallhorn, Paul; Palmiter, Christopher; Farmer, Jeffery; Lycans, Randall; Tiller, Bruce

2000-01-01

A general purpose, one dimensional fluid flow code has been interfaced with the thermal analysis program SINDA/G. The flow code, GFSSP, is capable of analyzing steady state and transient flow in a complex network. The flow code is capable of modeling several physical phenomena including compressibility effects, phase changes, body forces (such as gravity and centrifugal) and mixture thermodynamics for multiple species. The addition of GFSSP to SINDA/G provides a significant improvement in convective heat transfer modeling for SINDA/G. The interface development was conducted in two phases. This paper describes the first (which allows for steady and quasi-steady - unsteady solid, steady fluid - conjugate heat transfer modeling). The second (full transient conjugate heat transfer modeling) phase of the interface development will be addressed in a later paper. Phase 1 development has been benchmarked to an analytical solution with excellent agreement. Additional test cases for each development phase demonstrate desired features of the interface. The results of the benchmark case, three additional test cases and a practical application are presented herein.

Experimental investigation of lateral forces induced by flow through model labyrinth glands

NASA Technical Reports Server (NTRS)

Leong, Y. M. M. S.; Brown, R. D.

1984-01-01

The lateral forces induced by flow through model labyrinth glands were investigated. Circumferential pressure distributions, lateral forces and stiffness coefficients data obtained are discussed. The force system is represented as a negative spring and a tangential force orthogonal to eccentricity. The magnitude of these forces are dependent on eccentricity, entry swirl, rotor peripheral velocity and seal size. A pressure equalization chamber at midgland tests should in significantly reduced forces and stiffness coefficients.

Sources of Variability in Children’s Language Growth

PubMed Central

Huttenlocher, Janellen; Waterfall, Heidi; Vasilyeva, Marina; Vevea, Jack; Hedges, Larry V.

2010-01-01

The present longitudinal study examines the role of caregiver speech in language development, especially syntactic development, using 47 parent-child pairs of diverse SES background from 14 to 46 months. We assess the diversity (variety) of words and syntactic structures produced by caregivers and children. We use lagged correlations to examine language growth and its relation to caregiver speech. Results show substantial individual differences among children, and indicate that diversity of earlier caregiver speech significantly predicts corresponding diversity in later child speech. For vocabulary, earlier child speech also predicts later caregiver speech, suggesting mutual influence. However, for syntax, earlier child speech does not significantly predict later caregiver speech, suggesting a causal flow from caregiver to child. Finally, demographic factors, notably SES, are related to language growth, and are, at least partially, mediated by differences in caregiver speech, showing the pervasive influence of caregiver speech on language growth. PMID:20832781

Sensing Structures Inspired by Blind Cave Fish

NASA Astrophysics Data System (ADS)

McConney, Michael E.; Chen, Nannan; Lu, David; Anderson, Kyle D.; Hu, Huan; Liu, Chang; Tsukruk, Vladimir V.

2009-03-01

Blind cave fish, with degenerated non-functioning eyes, have evolved to ``see'' their hydrodynamic environment by using the flow receptors of the lateral line system. The hair-cell receptors are encapsulated in a hydrogel-like material, called a cupula, which increases the sensitivity of the hair-cell receptors by coupling their motion to the surrounding flowing media. We characterized the viscoelastic properties and of blind cave fish cupulae by using colloidal-probe spectroscopy in fluid. A photo-patternable hydrogel with similar properties was developed to mimic the fish receptor coupling structure. Flow-based measurements indicated that the hydrogels enhance drag through increased surface area, but also inherent material properties. These bio-inspired structures endowed micro-fabricated flow sensors with sensitivities rivaling that of fish.

Investigation of drag and heat reduction induced by a novel combinational lateral jet and spike concept in supersonic flows based on conjugate heat transfer approach

NASA Astrophysics Data System (ADS)

Zhu, Liang; Chen, Xiong; Li, Yingkun; Musa, Omer; Zhou, Changsheng

2018-01-01

When flying at supersonic or hypersonic speeds through the air, the drag and severe heating have a great impact on the vehicles, thus the drag reduction and thermal protection studies have attracted worldwide attention. In the current study, the Reynolds-averaged Navier-Stokes (RANS) equations coupled with the shear stress transport (SST) k - ω turbulence model have been employed to investigate the flow behavior induced by a novel combinational lateral jet and spike concept in supersonic flows. A coupling conjugate heat transfer (CHT) approach has been applied to investigate the thermal protection, which takes the heat transfer of structure into consideration. After the code was validated by the available experimental results and the gird independency analysis was carried out, the influences of the spike length ratio, lateral jet pressure ratio and lateral jet location on the drag and heat reduction performance are analyzed comprehensively. The obtained results show that a remarkable reduction in the drag and heat flux is achieved when a lateral jet is added to the spike. This implies that the combinational lateral jet and spike concept in supersonic flows have a great benefit to the drag and heat reduction. Both the drag and heat reduction decrease with the increase of the lateral jet pressure ratio, and the heat flux is more sensitive to the lateral jet pressure ratio. The lateral jet should not be located in the bottom of the spike in order to realize better drag and heat reduction performance. The drag and heat flux could be reduced by about 45% by reasonable lateral jet location. The drag decreases with the increase of the spike length ratio whereas the heat flux is affected by the spike length ratio just in a certain range.

Lateral and vertical distribution of downstream migrating juvenile sea lamprey

USGS Publications Warehouse

Sotola, V. Alex; Miehls, Scott M.; Simard, Lee G.; Marsden, J. Ellen

2018-01-01

Sea lamprey is considered an invasive and nuisance species in the Laurentian Great Lakes, Lake Champlain, and the Finger Lakes of New York and is a major focus of control efforts. Currently, management practices focus on limiting the area of infestation using barriers to block migratory adults, and lampricides to kill ammocoetes in infested tributaries. No control efforts currently target the downstream-migrating post-metamorphic life stage which could provide another management opportunity. In order to apply control methods to this life stage, a better understanding of their downstream movement patterns is needed. To quantify spatial distribution of downstream migrants, we deployed fyke and drift nets laterally and vertically across the stream channel in two tributaries of Lake Champlain. Sea lamprey was not randomly distributed across the stream width and lateral distribution showed a significant association with discharge. Results indicated that juvenile sea lamprey is most likely to be present in the thalweg and at midwater depths of the stream channel. Further, a majority of the catch occurred during high flow events, suggesting an increase in downstream movement activity when water levels are higher than base flow. Discharge and flow are strong predictors of the distribution of out-migrating sea lamprey, thus managers will need to either target capture efforts in high discharge areas of streams or develop means to guide sea lamprey away from these areas.

Lateral and vertical facies relationships of bedforms deposited by aggrading supercritical flows: From cyclic steps to humpback dunes

NASA Astrophysics Data System (ADS)

Lang, Jörg; Winsemann, Jutta

2013-10-01

The preservation of bedforms related to supercritical flows and hydraulic jumps is commonly considered to be rare in the geologic record, although these bedforms are known from a variety of depositional environments. This field-based study presents a detailed analysis of the sedimentary facies and stacking pattern of deposits of cyclic steps, chutes-and-pools, antidunes and humpback dunes from three-dimensional outcrops. The well exposed Middle Pleistocene successions from northern Germany comprise glacilacustrine ice-contact subaqueous fan and glacial lake-outburst flood deposits. The studied successions give new insights into the depositional architecture of bedforms related to supercritical flows and may serve as an analogue for other high-energy depositional environments such as fluvial settings, coarse-grained deltas or turbidite systems. Deposits of cyclic steps occur within the glacial lake-outburst flood succession and are characterised by lenticular scours infilled by gently to steeply dipping backsets. Cyclic steps formed due to acceleration and flow thinning when the glacial lake-outburst flood spilled over a push-moraine ridge. These bedforms are commonly laterally and vertically truncated and alternate with deposits of chutes-and-pools and antidunes. The subaqueous fan successions are dominated by laterally extensive sinusoidal waveforms, which are interpreted as deposits of aggrading stationary antidunes, which require quasi-steady flows at the lower limit of the supercritical flow stage and high rates of sedimentation. Humpback dunes are characterised by downflow divergent cross-stratification, displaying differentiation into topsets, foresets and bottomsets, and are interpreted as deposited at the transition from subcritical to supercritical flow conditions or vice versa. Gradual lateral and vertical transitions between humpback dunes and antidune deposits are very common. The absence of planar-parallel stratification in all studied successions suggests that the formation of these bedforms is suppressed in flows characterised by hydraulic jumps under highly aggradational conditions. The large-scale lateral and vertical successions of bedforms are interpreted as representing the temporal and spatial evolution of the initial supercritical flows, which was strongly affected by the occurrence of hydraulic jumps. Small-scale facies changes and the formation of individual bedforms are interpreted as controlled by fluctuating discharge, bed topography and pulsating unstable flows.

Length-scales of Slab-induced Asthenospheric Deformation from Geodynamic Modeling, Mantle Deformation Fabric, and Synthetic Shear Wave Splitting

NASA Astrophysics Data System (ADS)

Jadamec, M. A.; MacDougall, J.; Fischer, K. M.

2017-12-01

The viscosity structure of the Earth's interior is critically important, because it places a first order constraint on plate motion and mantle flow rates. Geodynamic models using a composite viscosity based on experimentally derived flow laws for olivine aggregates show that lateral viscosity variations emerge in the upper mantle due to the subduction dynamics. However, the length-scale of this transition is still not well understood. Two-dimensional numerical models of subduction are presented that investigate the effect of initial slab dip, maximum yield stress (slab strength), and viscosity formulation (Newtonian versus composite) on the emergent lateral viscosity variations in the upper-mantle and magnitude of slab-driven mantle flow velocity. Significant viscosity reductions occur in regions of large flow velocity gradients due to the weakening effect of the dislocation creep deformation mechanism. The dynamic reductions in asthenospheric viscosity (less than 1018 Pa s) occur within approximately 500 km from driving force of the slab, with peak flow velocities occurring in models with a lower yield stress (weaker slab) and higher stress exponent. This leads to a sharper definition of the rheological base of the lithosphere and implies lateral variability in tractions along the base of the lithosphere. As the dislocation creep mechanism also leads to mantle deformation fabric, we then examine the spatial variation in the LPO development in the asthenosphere and calculate synthetic shear wave splitting. The models show that olivine LPO fabric in the asthenosphere generally increases in alignment strength with increased proximity to the slab, but can be transient and spatially variable on small length scales. The vertical flow fields surrounding the slab tip can produce shear-wave splitting variations with back-azimuth that deviate from the predictions of uniform trench-normal anisotropy, a result that bears on the interpretation of complexity in shear-wave splitting observed in real subduction zones.

Channeling at the base of the lithosphere during the lateral flow of plume material beneath flow line hot spots

NASA Astrophysics Data System (ADS)

Sleep, Norman H.

2008-08-01

Chains of volcanic edifices lie along flow lines between plume-fed hot spots and the thin lithosphere at ridge axes. Discovery and Euterpe/Musicians Seamounts are two examples. An attractive hypothesis is that buoyant plume material flows along the base of the lithosphere perpendicular to isochrons. The plume material may conceivably flow in a broad front or flow within channels convectively eroded into the base to the lithosphere. A necessary but not sufficient condition for convective channeling is that the expected stagnant-lid heat flow for the maximum temperature of the plume material is comparable to the half-space surface heat flow of the oceanic lithosphere. Two-dimensional and three-dimensional numerical calculations confirm this inference. A second criterion for significant convective erosion is that it needs to occur before the plume material thins by lateral spreading. Scaling relationships indicate spreading and convection are closely related. Mathematically, the Nusselt number (ratio of convective to conductive heat flow in the plume material) scales with the flux (volume per time per length of flow front) of the plume material. A blob of unconfined plume material thus spreads before the lithosphere thins much and evolves to a slowly spreading and slowly convecting warm region in equilibrium with conduction into the base of the overlying lithosphere. Three-dimensional calculations illustrate this long-lasting (and hence observable) state of plume material away from its plume source. A different flow domain occurs around a stationary hot plume that continuously supplies hot material. The plume convectively erodes the overlying lithosphere, trapping the plume material near its orifice. The region of lithosphere underlain by plume material grows toward the ridge axis and laterally by convective thinning of the lithosphere at its edges. The hottest plume material channels along flow lines. Geologically, the regions of lithosphere underlain by either warm or hot plume material are likely to extend laterally away from the volcanic edifices whether or not channeling occurs.

Identification of runoff formation with two dyes in a mid-latitude mountain headwater

NASA Astrophysics Data System (ADS)

Vlcek, Lukas; Schneider, Philipp; Falatkova, Kristyna

2017-04-01

There have been numerous studies on subsurface flow in peat bog areas, as both water scarcity and floods have led to increased attention to this specific environment and its role within the hydrological cycle. In contrast, this experimental study identifies runoff formation at two opposite hillslopes in a peaty mountain headwater; a slope with organic soils (Peat / Histosol) and shallow groundwater ( 0.5 m below surface) complemented by a slope with mineral soils (Podzol) and no detectable groundwater within 2 m below surface. Differences in infiltration, percolation, and preferential flowpaths between both hillslopes could be identified by sprinkling experiments with two dyes - Brilliant Blue FCF and Fluorescein. By excavating dye-stained soil profiles parallel ("lateral") and perpendicular ("frontal") to the slopes' gradients - both within and downstream of the sprinkling plots - dye stained flow patterns in the soil could be clearly identified. The results show that biomat flow occurred at both hillslopes. The dye solutions infiltrated into the soil and continued either as lateral subsurface pipeflow (SSF), in the case of the Peat Bog, or percolated vertically towards the bedrock in the case of the Podzol. The study provides evidence that biomat flow (BMF) - shallow, lateral preferential flowpaths along decomposed tree roots or logs - is a major runoff formation process at the Peat Bog hillslope and in the adjacent riparian zone. This lateral flow through the organic soil hillslope (Peat Bog) towards the stream occurred mainly as shallow subsurface flow in organic layers above the groundwater level (BMF and SSF), but water partly percolates to the shallow groundwater via vertical macropores as well . In contrast, the mineral soil hillslope (Podzol) was mostly dominated by vertical percolation. Lateral flow occurred only on short distances in the organic topsoil as biomat flow (BMF). The sorptive tracer Brilliant Blue FCF successfully stained flowpaths in the soil at both hillslopes, whereas the identification of soil staining patterns by the relatively conservative tracer Fluorescein was limited on organic soil profiles.

Nitrate removal with lateral flow sulphur autotrophic denitrification reactor.

PubMed

Lv, Xiaomei; Shao, Mingfei; Li, Ji; Xie, Chuanbo

2014-01-01

An innovative lateral flow sulphur autotrophic denitrification (LFSAD) reactor was developed in this study; the treatment performance was evaluated and compared with traditional sulphur/limestone autotrophic denitrification (SLAD) reactor. Results showed that nitrite accumulation in the LFSAD reactor was less than 1.0 mg/L during the whole operation. Denitrification rate increased with the increased initial alkalinity and was approaching saturation when initial alkalinity exceeded 2.5 times the theoretical value. Higher influent nitrate concentration could facilitate nitrate removal capacity. In addition, denitrification efficiency could be promoted under an appropriate reflux ratio, and the highest nitrate removal percentage was achieved under reflux ratio of 200%, increased by 23.8% than that without reflux. Running resistance was only about 1/9 of that in SLAD reactor with equal amount of nitrate removed, which was the prominent excellence of the new reactor. In short, this study indicated that the developed reactor was feasible for nitrate removal from waters with lower concentrations, including contaminated surface water, groundwater or secondary effluent of municipal wastewater treatment with fairly low running resistance. The innovation in reactor design in this study may bring forth new ideas of reactor development of sulphur autotrophic denitrification for nitrate-contaminated water treatment.

Amplification-free point of care immunosensor for detecting type V collagen at a concentration level of ng/ml

NASA Astrophysics Data System (ADS)

Chung, Pei-Yu; Bracho-Sanchez, Evelyn R.; Jiang, Peng; Seagrave, JeanClare; Duncan, Matthew R.; Grotendorst, Gary R.; Schultz, Gregory; Batich, Christopher

2011-06-01

Point-of-care testing (POCT) is applicable in the immediate vicinity of the patient, where timely diagnosis or prognostic information could help doctors decide the following treatment. Among types of developed POCT, gold nanoparticle based lateral flow strip technology provides advantages such as simple operation, cost-effectiveness, and a user-friendly platform. Therefore, this type of POCT is most likely to be used in battlefields and developing countries. However, conventional lateral flow strips suffer from low detection limits. Although enzyme-linked amplification was demonstrated to improve the detection limit and sensitivity by stronger visible lines or by permitting electrochemical analytical instrumentation, the enzyme labels have potential to cause interference with other enzymes in our body fluids. To eliminate this limitation, we developed an amplification-free gold nanoparticle-based immunosensor applied for detecting collagen type V, which is produced or released abnormally during rejection of lung transplants and sulfur mustard exposure. By using suitable blocking protein to stabilize gold nanoparticles as the reporter probe, a low detection limit of ng/ml was achieved. This strategy is a promising platform for clinical POCT, with potential applications in military or disaster response.

Development of Lateral Flow Immunoassay for Antigen Detection in Human Angiostrongylus cantonensis Infection

PubMed Central

Chen, Mu-Xin; Chen, Jia-Xu; Chen, Shao-Hong; Huang, Da-Na; Ai, Lin; Zhang, Ren-Li

2016-01-01

Angiostrongyliasis is difficult to be diagnosed for the reason that no ideal method can be used. Serologic tests require specific equipment and are not always available in poverty-stricken zone and are time-consuming. A lateral flow immunoassay (LFIA) may be useful for angiostrongyliasis control. We established a LFIA for the diagnosis of angiostrongyliasis based on 2 monoclonal antibodies (mAbs) against antigens of Angiostrongylus cantonensis adults. The sensitivity and specificity were 91.1% and 100% in LFIA, while those of commercial ELISA kit was 97.8% and 86.3%, respectively. Youden index was 0.91 in LFIA and 0.84 in commercial ELISA kit. LFIA showed detection limit of 1 ng/ml of A. cantonensis ES antigens. This LFIA was simple, rapid, highly sensitive and specific, which opened an alternative approach for the diagnosis of human angiostrongyliasis. PMID:27417097

Modifying WEPP to improve streamflow simulation in a Pacific Northwest watershed

Treesearch

A. Srivastava; M. Dobre; J. Q. Wu; W. J. Elliot; E. A. Bruner; S. Dun; E. S. Brooks; I. S. Miller

2013-01-01

The assessment of water yield from hillslopes into streams is critical in managing water supply and aquatic habitat. Streamflow is typically composed of surface runoff, subsurface lateral flow, and groundwater baseflow; baseflow sustains the stream during the dry season. The Water Erosion Prediction Project (WEPP) model simulates surface runoff, subsurface lateral flow...

Dynamic Floodplain representation in hydrologic flood forecasting using WRF-Hydro modeling framework

NASA Astrophysics Data System (ADS)

Gangodagamage, C.; Li, Z.; Maitaria, K.; Islam, M.; Ito, T.; Dhondia, J.

2016-12-01

Floods claim more lives and damage more property than any other category of natural disaster in the Continental United States. A system that can demarcate local flood boundaries dynamically could help flood prone communities prepare for and even prevent from catastrophic flood events. Lateral distance from the centerline of the river to the right and left floodplains for the water levels coming out of the models at each grid location have not been properly integrated with the national hydrography dataset (NHDPlus). The NHDPlus dataset represents the stream network with feature classes such as rivers, tributaries, canals, lakes, ponds, dams, coastlines, and stream gages. The NHDPlus dataset consists of approximately 2.7 million river reaches defining how surface water drains to the ocean. These river reaches have upstream and downstream nodes and basic parameters such as flow direction, drainage area, reach slope etc. We modified an existing algorithm (Gangodagamage et al., 2007) to provide lateral distance from the centerline of the river to the right and left floodplains for the flows simulated by models. Previous work produced floodplain boundaries for static river stages (i.e. 3D metric: distance along the main stem, flow depth, lateral distance from river center line). Our new approach introduces the floodplain boundary for variable water levels at each reach with the fourth dimension, time. We use modeled flows from WRF-Hydro and demarcate the right and left lateral boundaries of inundation dynamically by appropriately mapping discharges into hydraulically corrected stages. Backwater effects from the mainstem to tributaries are considered and proper corrections are applied for the tributary inundations. We obtained river stages by optimizing reach level channel parameters using newly developed stream flow routing algorithm. Non uniform inundations are mapped at each NHDplus reach (upstream and downstream nodes) and spatial interpolation is carried out on a normalized digital elevation model (always streams are at zero elevations) to obtain the smooth flood boundaries between adjacent reaches. The validation of the dynamic inundation boundaries is performed using multi-temporal satellite datasets as well as HEC-RAS hydrodynamic model results for selected streams for previous flood events.

Eddy Flow during Magma Emplacement: The Basemelt Sill, Antarctica

NASA Astrophysics Data System (ADS)

Petford, N.; Mirhadizadeh, S.

2014-12-01

The McMurdo Dry Valleys magmatic system, Antarctica, forms part of the Ferrar dolerite Large Igneous Province. Comprising a vertical stack of interconnected sills, the complex provides a world-class example of pervasive lateral magma flow on a continental scale. The lowermost intrusion (Basement Sill) offers detailed sections through the now frozen particle macrostructure of a congested magma slurry1. Image-based numerical modelling where the intrusion geometry defines its own unique finite element mesh allows simulations of the flow regime to be made that incorporate realistic magma particle size and flow geometries obtained directly from field measurements. One testable outcome relates to the origin of rhythmic layering where analytical results imply the sheared suspension intersects the phase space for particle Reynolds and Peclet number flow characteristic of macroscopic structures formation2. Another relates to potentially novel crystal-liquid segregation due to the formation of eddies locally at undulating contacts at the floor and roof of the intrusion. The eddies are transient and mechanical in origin, unrelated to well-known fluid dynamical effects around obstacles where flow is turbulent. Numerical particle tracing reveals that these low Re number eddies can both trap (remove) and eject particles back into the magma at a later time according to their mass density. This trapping mechanism has potential to develop local variations in structure (layering) and magma chemistry that may otherwise not occur where the contact between magma and country rock is linear. Simulations indicate that eddy formation is best developed where magma viscosity is in the range 1-102 Pa s. Higher viscosities (> 103 Pa s) tend to dampen the effect implying eddy development is most likely a transient feature. However, it is nice to think that something as simple as a bumpy contact could impart physical and by implication chemical diversity in igneous rocks. 1Marsh, D.B. (2004), A magmatic mush column Rosetta stone: the McMurdo Dry Valleys of Antarcica. EOS, 85, 497-502. 2Petford, N. (2009), Which Effective Viscosity? Mineralogical Magazine, 73, 167-191. Fig. 1. Numerical simulation in the geometry showing magma flow field and eddy formation where circulating magma is trapped. Streamlines track particle orbits.

Automated Low-Cost Smartphone-Based Lateral Flow Saliva Test Reader for Drugs-of-Abuse Detection

PubMed Central

Carrio, Adrian; Sampedro, Carlos; Sanchez-Lopez, Jose Luis; Pimienta, Miguel; Campoy, Pascual

2015-01-01

Lateral flow assay tests are nowadays becoming powerful, low-cost diagnostic tools. Obtaining a result is usually subject to visual interpretation of colored areas on the test by a human operator, introducing subjectivity and the possibility of errors in the extraction of the results. While automated test readers providing a result-consistent solution are widely available, they usually lack portability. In this paper, we present a smartphone-based automated reader for drug-of-abuse lateral flow assay tests, consisting of an inexpensive light box and a smartphone device. Test images captured with the smartphone camera are processed in the device using computer vision and machine learning techniques to perform automatic extraction of the results. A deep validation of the system has been carried out showing the high accuracy of the system. The proposed approach, applicable to any line-based or color-based lateral flow test in the market, effectively reduces the manufacturing costs of the reader and makes it portable and massively available while providing accurate, reliable results. PMID:26610513

Assessing hemispheric specialization for processing arithmetic skills in adults: A functional transcranial doppler ultrasonography (fTCD) study.

PubMed

Connaughton, Veronica M; Amiruddin, Azhani; Clunies-Ross, Karen L; French, Noel; Fox, Allison M

2017-05-01

A major model of the cerebral circuits that underpin arithmetic calculation is the triple-code model of numerical processing. This model proposes that the lateralization of mathematical operations is organized across three circuits: a left-hemispheric dominant verbal code; a bilateral magnitude representation of numbers and a bilateral Arabic number code. This study simultaneously measured the blood flow of both middle cerebral arteries using functional transcranial Doppler ultrasonography to assess hemispheric specialization during the performance of both language and arithmetic tasks. The propositions of the triple-code model were assessed in a non-clinical adult group by measuring cerebral blood flow during the performance of multiplication and subtraction problems. Participants were 17 adults aged between 18-27 years. We obtained laterality indices for each type of mathematical operation and compared these in participants with left-hemispheric language dominance. It was hypothesized that blood flow would lateralize to the left hemisphere during the performance of multiplication operations, but would not lateralize during the performance of subtraction operations. Hemispheric blood flow was significantly left lateralized during the multiplication task, but was not lateralized during the subtraction task. Compared to high spatial resolution neuroimaging techniques previously used to measure cerebral lateralization, functional transcranial Doppler ultrasonography is a cost-effective measure that provides a superior temporal representation of arithmetic cognition. These results provide support for the triple-code model of arithmetic processing and offer complementary evidence that multiplication operations are processed differently in the adult brain compared to subtraction operations. Copyright © 2017 Elsevier B.V. All rights reserved.

Lateral-flow colloidal gold-based immunoassay for the rapid detection of deoxynivalenol with two indicator ranges.

PubMed

Kolosova, Anna Yu; Sibanda, Liberty; Dumoulin, Frédéric; Lewis, Janet; Duveiller, Etienne; Van Peteghem, Carlos; De Saeger, Sarah

2008-06-02

A lateral-flow immunoassay using a colloidal gold-labelled monoclonal antibody was developed for the rapid detection of deoxynivalenol (DON). Different parameters, such as the amount of immunoreagents, type of the materials, composition of the blocking solution and of the detector reagent mixture, were investigated to provide the optimum assay performance. The experimental results demonstrated that such a visual test had an indicator range rather than a cut-off value. Thus, tests for DON determination with two different indicator ranges of 250-500 and 1000-2000 microg kg(-1) were designed. The method allowed detection of DON at low and high concentration levels, which could be useful for research and practical purposes. The assay applied to spiked wheat and pig feed samples demonstrated accurate and reproducible results. The applicability of the developed lateral-flow test was also confirmed under real field conditions. The test strips prepared in Belgium were sent to Mexico, where they were used for the screening of DON contamination in different bread wheat entries from Fusarium Head Blight inoculated plots. The results were compared with those obtained by ELISA and LC-MS/MS. A poor correlation between ELISA and LC-MS/MS was observed. Visual results of the dipstick tests were in a good agreement with the results of the LC-MS/MS method. Coupled with a simple and fast sample preparation, this qualitative one-step test based on the visual evaluation of results did not require any equipment. Results could be obtained within 10 min. The described assay format can be used as a simple, rapid, cost-effective and robust on-site screening tool for mycotoxin contamination in different agricultural commodities.

Generation of Accurate Lateral Boundary Conditions for a Surface-Water Groundwater Interaction Model

NASA Astrophysics Data System (ADS)

Khambhammettu, P.; Tsou, M.; Panday, S. M.; Kool, J.; Wei, X.

2010-12-01

The 106 mile long Peace River in Florida flows south from Lakeland to Charlotte Harbor and has a drainage basin of approximately 2,350 square miles. A long-term decline in stream flows and groundwater potentiometric levels has been observed in the region. Long-term trends in rainfall, along with effects of land use changes on runoff, surface-water storage, recharge and evapotranspiration patterns, and increased groundwater and surface-water withdrawals have contributed to this decline. The South West Florida Water Management District (SWFWMD) has funded the development of the Peace River Integrated Model (PRIM) to assess the effects of land use, water use, and climatic changes on stream flows and to evaluate the effectiveness of various management alternatives for restoring stream flows. The PRIM was developed using MODHMS, a fully integrated surface-water groundwater flow and transport simulator developed by HydroGeoLogic, Inc. The development of the lateral boundary conditions (groundwater inflow and outflow) for the PRIM in both historical and predictive contexts is discussed in this presentation. Monthly-varying specified heads were used to define the lateral boundary conditions for the PRIM. These head values were derived from the coarser Southern District Groundwater Model (SDM). However, there were discrepancies between the simulated SDM heads and measured heads: the likely causes being spatial (use of a coarser grid) and temporal (monthly average pumping rates and recharge rates) approximations in the regional SDM. Finer re-calibration of the SDM was not feasible, therefore, an innovative approach was adopted to remove the discrepancies. In this approach, point discrepancies/residuals between the observed and simulated heads were kriged with an appropriate variogram to generate a residual surface. This surface was then added to the simulated head surface of the SDM to generate a corrected head surface. This approach preserves the trends associated with groundwater pumping / recharge in the SDM and adds the kriged residual surface as variations back to the trend. The variations could be from the scale effects of grid resolution and from the temporal averaging of stresses (pumping, recharge, etc.,). The validity of the approach is demonstrated by visual and statistical comparison of the observed and simulated heads before and after correction. For predictive simulations, an Artificial Neural Network was trained to predict heads at monitoring wells based on precipitation and pumping. These predicted head values could then be used as surrogate observations for correcting the results of the regional SDM. In summary, an appropriate approach to link a regional groundwater model to a detailed surface-water groundwater interaction model is demonstrated with an example.

Numerical simulation of hydrothermal circulation in the Cascade Range, north-central Oregon

USGS Publications Warehouse

Ingebritsen, S.E.; Paulson, K.M.

1990-01-01

Alternate conceptual models to explain near-surface heat-flow observations in the central Oregon Cascade Range involve (1) an extensive mid-crustal magmatic heat source underlying both the Quaternary arc and adjacent older rocks or (2) a narrower deep heat source which is flanked by a relatively shallow conductive heat-flow anomaly caused by regional ground-water flow (the lateral-flow model). Relative to the mid-crustal heat source model, the lateral-flow model suggests a more limited geothermal resource base, but a better-defined exploration target. We simulated ground-water flow and heat transport through two cross sections trending west from the Cascade range crest in order to explore the implications of the two models. The thermal input for the alternate conceptual models was simulated by varying the width and intensity of a basal heat-flow anomaly and, in some cases, by introducing shallower heat sources beneath the Quaternary arc. Near-surface observations in the Breitenbush Hot Springs area are most readily explained in terms of lateral heat transport by regional ground-water flow; however, the deep thermal structure still cannot be uniquely inferred. The sparser thermal data set from the McKenzie River area can be explained either in terms of deep regional ground-water flow or in terms of a conduction-dominated system, with ground-water flow essentially confined to Quaternary rocks and fault zones.

A Review of Current Methods for Analysis of Mycotoxins in Herbal Medicines

PubMed Central

Zhang, Lei; Dou, Xiao-Wen; Zhang, Cheng; Logrieco, Antonio F.; Yang, Mei-Hua

2018-01-01

The presence of mycotoxins in herbal medicines is an established problem throughout the entire world. The sensitive and accurate analysis of mycotoxin in complicated matrices (e.g., herbs) typically involves challenging sample pretreatment procedures and an efficient detection instrument. However, although numerous reviews have been published regarding the occurrence of mycotoxins in herbal medicines, few of them provided a detailed summary of related analytical methods for mycotoxin determination. This review focuses on analytical techniques including sampling, extraction, cleanup, and detection for mycotoxin determination in herbal medicines established within the past ten years. Dedicated sections of this article address the significant developments in sample preparation, and highlight the importance of this procedure in the analytical technology. This review also summarizes conventional chromatographic techniques for mycotoxin qualification or quantitation, as well as recent studies regarding the development and application of screening assays such as enzyme-linked immunosorbent assays, lateral flow immunoassays, aptamer-based lateral flow assays, and cytometric bead arrays. The present work provides a good insight regarding the advanced research that has been done and closes with an indication of future demand for the emerging technologies. PMID:29393905

Quantum-Dot-Based Lateral Flow Immunoassay for Detection of Neonicotinoid Residues in Tea Leaves.

PubMed

Wang, Shuangjie; Liu, Ying; Jiao, Shasha; Zhao, Ying; Guo, Yirong; Wang, Mengcen; Zhu, Guonian

2017-11-22

Neonicotinoid insecticides are commonly used for pest control on tea plantations as a result of their broad-spectrum activity. However, neonicotinoid residues released from tea leaves into tea infusions pose a dietary risk to consumers. Therefore, a rapid, sensitive, and reliable on-site detection method for neonicotinoids is needed. We developed a quantum-dot-based fluorescent lateral flow immunochromatographic strip (LFICS) combined with a broad-specific antibody for detection of typical neonicotinoids (imidacloprid, imidaclothiz, and clothianidin), with sensitivities [50% inhibitory concentration (IC 50 )] of 0.104-0.33 ng/mL and visual detection limits of 0.5-1 ng/mL. The strip assay could be completed in less than 30 min. Using the LFICS to analyze spiked tea samples (green tea, black tea, and oolong tea), the average recovery of the three neonicotinoids ranged between 71 and 111%, with the coefficient of variation below 12%. The results from the LFICS tests for field samples were consistent with results from ultraperformance liquid chromatography-tandem mass spectrometry. The newly developed strip is a useful tool for the on-site detection of neonicotinoid residues in tea.

A rapid burst in hotspot motion through the interaction of tectonics and deep mantle flow.

PubMed

Hassan, Rakib; Müller, R Dietmar; Gurnis, Michael; Williams, Simon E; Flament, Nicolas

2016-05-12

Volcanic hotspot tracks featuring linear progressions in the age of volcanism are typical surface expressions of plate tectonic movement on top of narrow plumes of hot material within Earth's mantle. Seismic imaging reveals that these plumes can be of deep origin--probably rooted on thermochemical structures in the lower mantle. Although palaeomagnetic and radiometric age data suggest that mantle flow can advect plume conduits laterally, the flow dynamics underlying the formation of the sharp bend occurring only in the Hawaiian-Emperor hotspot track in the Pacific Ocean remains enigmatic. Here we present palaeogeographically constrained numerical models of thermochemical convection and demonstrate that flow in the deep lower mantle under the north Pacific was anomalously vigorous between 100 million years ago and 50 million years ago as a consequence of long-lasting subduction systems, unlike those in the south Pacific. These models show a sharp bend in the Hawaiian-Emperor hotspot track arising from the interplay of plume tilt and the lateral advection of plume sources. The different trajectories of the Hawaiian and Louisville hotspot tracks arise from asymmetric deformation of thermochemical structures under the Pacific between 100 million years ago and 50 million years ago. This asymmetric deformation waned just before the Hawaiian-Emperor bend developed, owing to flow in the deepest lower mantle associated with slab descent in the north and south Pacific.

Vertebrate Left-Right Asymmetry: What Can Nodal Cascade Gene Expression Patterns Tell Us?

PubMed

Schweickert, Axel; Ott, Tim; Kurz, Sabrina; Tingler, Melanie; Maerker, Markus; Fuhl, Franziska; Blum, Martin

2017-12-29

Laterality of inner organs is a wide-spread characteristic of vertebrates and beyond. It is ultimately controlled by the left-asymmetric activation of the Nodal signaling cascade in the lateral plate mesoderm of the neurula stage embryo, which results from a cilia-driven leftward flow of extracellular fluids at the left-right organizer. This scenario is widely accepted for laterality determination in wildtype specimens. Deviations from this norm come in different flavors. At the level of organ morphogenesis, laterality may be inverted (situs inversus) or non-concordant with respect to the main body axis (situs ambiguus or heterotaxia). At the level of Nodal cascade gene activation, expression may be inverted, bilaterally induced, or absent. In a given genetic situation, patterns may be randomized or predominantly lacking laterality (absence or bilateral activation). We propose that the distributions of patterns observed may be indicative of the underlying molecular defects, with randomizations being primarily caused by defects in the flow-generating ciliary set-up, and symmetrical patterns being the result of impaired flow sensing, on the left, the right, or both sides. This prediction, the reasoning of which is detailed in this review, pinpoints functions of genes whose role in laterality determination have remained obscure.

The Determination of Forces and Moments on a Gimballed SRM Nozzle Using a Cold Flow Model

NASA Technical Reports Server (NTRS)

Whitesides, R. Harold; Bacchus, David L.; Hengel, John E.

1994-01-01

The Solid Rocket Motor Air Flow Facility (SAF) at NASA Marshall Space Flight Center was used to characterize the flow in the critical aft end and nozzle of a solid propellant rocket motor (SRM) as part of the design phase of development. The SAF is a high pressure, blowdown facility which supplies a controlled flow of air to a subscale model of the internal port and nozzle of a SRM to enable measurement and evaluation of the flow field and surface pressure distributions. The ASRM Aft Section/Nozzle Model is an 8 percent scale model of the 19 second burn time aft port geometry and nozzle of the Advanced Solid Rocket Motor, the now canceled new generation space Shuttle Booster. It has the capability to simulate fixed nozzle gimbal angles of 0, 4, and 8 degrees. The model was tested at full scale motor Reynolds Numbers with extensive surface pressure instrumentation to enable detailed mapping of the surface pressure distributions over the nozzle interior surface, the exterior surface of the nozzle nose and the surface of the simulated propellant grain in the aft motor port. A mathematical analysis and associated numerical procedure were developed to integrate the measured surface pressure distributions to determine the lateral and axial forces on the moveable section of the nozzle, the effective model thrust and the effective aerodynamic thrust vector (as opposed to the geometric nozzle gimbal angle). The nozzle lateral and axial aerodynamic loads and moments about the pivot point are required for design purposes and require complex, three dimensional flow analyses. The alignment of the thrust vector with the nozzle geometric centerline is also a design requirement requiring three dimensional analyses which were supported by this experimental program. The model was tested with all three gimbal angles at three pressure levels to determine Reynolds number effects and reproducibility. This program was successful in demonstrating that a measured surface pressure distribution could be integrated to determine the lateral and axial loads, moments and thrust vector alignment for the scaled model of a large space booster nozzle. Numerical results were provided which are scaleable to the full scale rocket motor and can be used as benchmark data for 3-D CFD analyses.

Fluid flow near the surface of earth's outer core

NASA Technical Reports Server (NTRS)

Bloxham, Jeremy; Jackson, Andrew

1991-01-01

This review examines the recent attempts at extracting information on the pattern of fluid flow near the surface of the outer core from the geomagnetic secular variation. Maps of the fluid flow at the core surface are important as they may provide some insight into the process of the geodynamo and may place useful constraints on geodynamo models. In contrast to the case of mantle convection, only very small lateral variations in core density are necessary to drive the flow; these density variations are, by several orders of magnitude, too small to be imaged seismically; therefore, the geomagnetic secular variation is utilized to infer the flow. As substantial differences exist between maps developed by different researchers, the possible underlying reasons for these differences are examined with particular attention given to the inherent problems of nonuniqueness.

Supercritical flow characteristics at abrupt expansion structure

NASA Astrophysics Data System (ADS)

Lim, Jia Jun; Puay, How Tion; Zakaria, Nor Azazi

2017-10-01

When dealing with the design of a hydraulic structure, lateral expansion is often necessary for flow emerging at high velocity served as a cross-sectional transition. If the abrupt expansion structure is made to diverge rapidly, it will cause the major part of the flow fail to follow the boundaries. If the transition is too gradual, it will result in a waste of structural material. A preliminary study on the flow structure near the expansion and its relationship with flow parameter is carried out in this study. A two-dimensional depth-averaged model is developed to simulate the supercritical flow at the abrupt expansion structure. Constrained Interpolation Profile (CIP) scheme (which is of third order accuracy) is adopted in the numerical model. Results show that the flow structure and flow characteristics at the abrupt expansion can be reproduced numerically. The validation of numerical result is done against analytical studies. The result from numerical simulation showed good agreement with the analytical solution.

Using Value-Focused Thinking to Evaluate the Use of Innovative Stormwater Management Technologies on Air Force Installations

DTIC Science & Technology

2007-03-01

11 Figure 2: Comparison of Water Cycle across Varying Levels of Development...Comparison of Water Cycle across Varying Levels of Development (PWUD, 2006). 2.2.1. Problems Increased volume and flow rate of stormwater runoff...in which the water cycle is undisturbed. The movement of Americans in the later half of the twentieth century from cities to suburbs has resulted

Development of real-time and lateral flow strip reverse transcription recombinase polymerase Amplification assays for rapid detection of peste des petits ruminants virus.

PubMed

Yang, Yang; Qin, Xiaodong; Song, Yiming; Zhang, Wei; Hu, Gaowei; Dou, Yongxi; Li, Yanmin; Zhang, Zhidong

2017-02-07

Peste des petits ruminants (PPR) is an economically important, Office International des Epizooties (OIE) notifiable, transboundary viral disease of small ruminants such as sheep and goat. PPR virus (PPRV), a negative-sense single-stranded RNA virus, is the causal agent of PPR. Therefore, sensitive, specific and rapid diagnostic assay for the detection of PPRV are necessary to accurately and promptly diagnose suspected case of PPR. In this study, reverse transcription recombinase polymerase amplification assays using real-time fluorescent detection (real-time RT-RPA assay) and lateral flow strip detection (LFS RT-RPA assay) were developed targeting the N gene of PPRV. The sensitivity of the developed real-time RT-RPA assay was as low as 100 copies per reaction within 7 min at 40 °C with 95% reliability; while the sensitivity of the developed LFS RT-RPA assay was as low as 150 copies per reaction at 39 °C in less than 25 min. In both assays, there were no cross-reactions with sheep and goat pox viruses, foot-and-mouth disease virus and Orf virus. These features make RPA assay promising candidates either in field use or as a point of care diagnostic technique.

Label-free imaging of developing vasculature in zebrafish with phase variance optical coherence microscopy

NASA Astrophysics Data System (ADS)

Chen, Yu; Fingler, Jeff; Trinh, Le A.; Fraser, Scott E.

2016-03-01

A phase variance optical coherence microscope (pvOCM) has been created to visualize blood flow in the vasculature of zebrafish embryos, without using exogenous labels. The pvOCM imaging system has axial and lateral resolutions of 2 μm in tissue, and imaging depth of more than 100 μm. Imaging of 2-5 days post-fertilization zebrafish embryos identified the detailed structures of somites, spinal cord, gut and notochord based on intensity contrast. Visualization of the blood flow in the aorta, veins and intersegmental vessels was achieved with phase variance contrast. The pvOCM vasculature images were confirmed with corresponding fluorescence microscopy of a zebrafish transgene that labels the vasculature with green fluorescent protein. The pvOCM images also revealed functional information of the blood flow activities that is crucial for the study of vascular development.

High frequency lateral flow affinity assay using superparamagnetic nanoparticles

NASA Astrophysics Data System (ADS)

Lago-Cachón, D.; Rivas, M.; Martínez-García, J. C.; Oliveira-Rodríguez, M.; Blanco-López, M. C.; García, J. A.

2017-02-01

Lateral flow assay is one of the simplest and most extended techniques in medical diagnosis for point-of-care testing. Although it has been traditionally a positive/negative test, some work has been lately done to add quantitative abilities to lateral flow assay. One of the most successful strategies involves magnetic beads and magnetic sensors. Recently, a new technique of superparamagnetic nanoparticle detection has been reported, based on the increase of the impedance induced by the nanoparticles on a RF-current carrying copper conductor. This method requires no external magnetic field, which reduces the system complexity. In this work, nitrocellulose membranes have been installed on the sensor, and impedance measurements have been carried out during the sample diffusion by capillarity along the membrane. The impedance of the sensor changes because of the presence of magnetic nanoparticles. The results prove the potentiality of the method for point-of-care testing of biochemical substances and nanoparticle capillarity flow studies.

A generalised model of secondary circulation for a wide range of geophysical flows from direct observations of natural turbidity currents

NASA Astrophysics Data System (ADS)

Azpiroz, M.; Cartigny, M.; Sumner, E. J.; Talling, P.; Parsons, D. R.; Clare, M. A.; Cooper, C.

2017-12-01

Turbidity currents transport sediment through submarine channel systems for hundreds of kilometres to form vast deposits of sediment in the deep sea called submarine fans. The largest submarine fans are fed by meandering channels suggesting that bends may enhance sediment transport distances. The interaction between meander bends and turbidity currents has been a topic of intense debate. Due to the absence of observations of deep-sea turbidity currents flowing through meander bends, our understanding has been based on experimental and numerical models. Measurements of geophysical flows demonstrate a common helical flow structure around meanders. Previous work has demonstrated that helical circulation in rivers is dominated by a single helix that rotates towards the inner bend at near-bed depths. In contrast, initial numerical and experimental models for turbidity currents found both river-like and river-reversed circulations. Saline flows in well-mixed estuaries show a river-like basal helical circulation, while stratified estuaries and saline flows are river-reversed. The existence of lateral stratification in stratified flows is thought to be the key factor in the change of direction of rotation. Stratification causes lateral pressure gradients that can govern the rotation of the flow helix. Turbidity currents are stratified due to their upwards-decreasing sediment load. It has therefore been proposed that stratified turbidity currents behave like stratified saline flow, but this hypothesis remains so far untested. Here we present the first observations of the helical flow in turbidity currents, which occurred within the deep-sea Congo Canyon. The measurements show a consistent river-reversed pattern downstream of the bend apex. Those results lead us to develop a new generalised model for a wide range of flows around meanders. Our conclusions have implications for understanding the flow erosional and depositional patterns, the evolution of channel systems and the architecture of the depositional record.

Intrinsic particle-induced lateral transport in microchannels

PubMed Central

Amini, Hamed; Sollier, Elodie; Weaver, Westbrook M.; Di Carlo, Dino

2012-01-01

In microfluidic systems at low Reynolds number, the flow field around a particle is assumed to maintain fore-aft symmetry, with fluid diverted by the presence of a particle, returning to its original streamline downstream. This current model considers particles as passive components of the system. However, we demonstrate that at finite Reynolds number, when inertia is taken into consideration, particles are not passive elements in the flow but significantly disturb and modify it. In response to the flow field, particles translate downstream while rotating. The combined effect of the flow of fluid around particles, particle rotation, channel confinement (i.e., particle dimensions approaching those of the channel), and finite fluid inertia creates a net recirculating flow perpendicular to the primary flow direction within straight channels that resembles the well-known Dean flow in curved channels. Significantly, the particle generating this flow remains laterally fixed as it translates downstream and only the fluid is laterally transferred. Therefore, as the particles remain inertially focused, operations can be performed around the particles in a way that is compatible with downstream assays such as flow cytometry. We apply this particle-induced transfer to perform fluid switching and mixing around rigid microparticles as well as deformable cells. This transport phenomenon, requiring only a simple channel geometry with no external forces to operate, offers a practical approach for fluid transfer at high flow rates with a wide range of applications, including sample preparation, flow reaction, and heat transfer. PMID:22761309

Evaluation of a lateral flow immunoassay for field identification of Solenopsis invicta (Hymenoptera: Formicidae) in Australia

USDA-ARS?s Scientific Manuscript database

In an effort to improve surveillance capacity for the exotic red imported fire ant, Solenopsis invicta, a lateral flow immunoassay (LFA) was recently evaluated by Biosecurity Queensland staff in Australia. The purpose of the research was to assess the ability of the fire ant LFA to discriminate S. i...

The performance characteristics of lateral flow devices with 2 strains of highly pathogenic avian influenza virus

USDA-ARS?s Scientific Manuscript database

Lateral flow devices (LFD) are commercially available and provide a fast, highly specific, on-site test for avian influenza. Because of the low analytic sensitivity of LFD tests at low virus concentrations, targeted sampling of sick and dead birds has been proposed in order to increase detection pr...

A physically-based Distributed Hydrologic Model for Tropical Catchments

NASA Astrophysics Data System (ADS)

Abebe, N. A.; Ogden, F. L.

2010-12-01

Hydrological models are mathematical formulations intended to represent observed hydrological processes in a watershed. Simulated watersheds in turn vary in their nature based on their geographic location, altitude, climatic variables and geology and soil formation. Due to these variations, available hydrologic models vary in process formulation, spatial and temporal resolution and data demand. Many tropical watersheds are characterized by extensive and persistent biological activity and a large amount of rain. The Agua Salud catchments located within the Panama Canal Watershed, Panama, are such catchments identified by steep rolling topography, deep soils derived from weathered bedrock, and limited exposed bedrock. Tropical soils are highly affected by soil cracks, decayed tree roots and earthworm burrows forming a network of preferential flow paths that drain to a perched water table, which forms at a depth where the vertical hydraulic conductivity is significantly reduced near the bottom of the bioturbation layer. We have developed a physics-based, spatially distributed, multi-layered hydrologic model to simulate the dominant processes in these tropical watersheds. The model incorporates the major flow processes including overland flow, channel flow, matrix and non-Richards film flow infiltration, lateral downslope saturated matrix and non-Darcian pipe flow in the bioturbation layer, and deep saturated groundwater flow. Emphasis is given to the modeling of subsurface unsaturated zone soil moisture dynamics and the saturated preferential lateral flow from the network of macrospores. Preliminary results indicate that the model has the capability to simulate the complex hydrological processes in the catchment and will be a useful tool in the ongoing comprehensive ecohydrological studies in tropical catchments, and help improve our understanding of the hydrological effects of deforestation and aforestation.

Hydraulic characteristics of, and ground-water flow in, coal-bearing rocks of southwestern Virginia

USGS Publications Warehouse

Harlow, George E.; LeCain, Gary D.

1993-01-01

This report presents the results of a study by the U.S Geological Survey, in cooperation with the Virginia Department of Mines, Minerals, and Energy, Division of Mined Land Reclamation, and the Powell River Project, to describe the hydraulic characteristics of major water-bearing zones in the coal-bearing rocks of southwestern Virginia and to develop a conceptual model of the ground-water-flow system. Aquifer testing in1987 and 1988 of 9-ft intervals in coal-exploration coreholes indicates that transmissivity decreases with increasing depth. Most rock types are permeable to a depth of approximately 100 ft; however, only coal seams are consistently permeable (transmissivity greater than 0.001 ft/d) at depths greater than 200 ft . Constant-head injection testing of rock intervals adjacent to coal seams usually indicated lower values of transmissivity than those values obtained when coal seams were isolated within the test interval; thus, large values of horizontal hydraulic conductivity at depth are associated with coal seams. Potentiometric-head measurements indicate that high topographic areas (ridges) function as recharge areas; water infiltrates through the surface, percolates into regolith, and flows downward and laterally through fractures in the shallow bedrock. Hydraulic conductivity decreases with increasing depth, and ground water flows primarily in the lateral direction along fractures or bedding planes or through coal seams. If vertical hydraulic conductivity is negligible, ground water continues to flow laterally, discharging as springs or seeps on hill slopes. Where vertical hydraulic conductivity is appreciable, groundwater follows a stair step path through the regolith, fractures, bedding planes, and coal seams, discharging to streams and (or) recharging coal seams at depth. Permeable coal seams probably underlie valleys in the region; however, aquifer-test data indicate that the horizontal hydraulic conductivity of coal is a function of depth and probably decreases under ridges because of increased overburden pressures. Ground water beneath valleys that does not discharge to streams probably flows down gradient as underflow beneath the streams. Topographic relief in the area provides large hydraulic-head differences (greater than 300 ft in some instances) for the ground-water-flow system. Transmissivity data from the range of depths tested during this study indicate that most ground-water flow takes place at moderate depths (less than 300 ft) and that little deep regional ground-water flow occurs.

Low-Cost 3-D Flow Estimation of Blood With Clutter.

PubMed

Wei, Siyuan; Yang, Ming; Zhou, Jian; Sampson, Richard; Kripfgans, Oliver D; Fowlkes, J Brian; Wenisch, Thomas F; Chakrabarti, Chaitali

2017-05-01

Volumetric flow rate estimation is an important ultrasound medical imaging modality that is used for diagnosing cardiovascular diseases. Flow rates are obtained by integrating velocity estimates over a cross-sectional plane. Speckle tracking is a promising approach that overcomes the angle dependency of traditional Doppler methods, but suffers from poor lateral resolution. Recent work improves lateral velocity estimation accuracy by reconstructing a synthetic lateral phase (SLP) signal. However, the estimation accuracy of such approaches is compromised by the presence of clutter. Eigen-based clutter filtering has been shown to be effective in removing the clutter signal; but it is computationally expensive, precluding its use at high volume rates. In this paper, we propose low-complexity schemes for both velocity estimation and clutter filtering. We use a two-tiered motion estimation scheme to combine the low complexity sum-of-absolute-difference and SLP methods to achieve subpixel lateral accuracy. We reduce the complexity of eigen-based clutter filtering by processing in subgroups and replacing singular value decomposition with less compute-intensive power iteration and subspace iteration methods. Finally, to improve flow rate estimation accuracy, we use kernel power weighting when integrating the velocity estimates. We evaluate our method for fast- and slow-moving clutter for beam-to-flow angles of 90° and 60° using Field II simulations, demonstrating high estimation accuracy across scenarios. For instance, for a beam-to-flow angle of 90° and fast-moving clutter, our estimation method provides a bias of -8.8% and standard deviation of 3.1% relative to the actual flow rate.

Flow-Centric, Back-in-Time Debugging

NASA Astrophysics Data System (ADS)

Lienhard, Adrian; Fierz, Julien; Nierstrasz, Oscar

Conventional debugging tools present developers with means to explore the run-time context in which an error has occurred. In many cases this is enough to help the developer discover the faulty source code and correct it. However, rather often errors occur due to code that has executed in the past, leaving certain objects in an inconsistent state. The actual run-time error only occurs when these inconsistent objects are used later in the program. So-called back-in-time debuggers help developers step back through earlier states of the program and explore execution contexts not available to conventional debuggers. Nevertheless, even Back-in-Time Debuggers do not help answer the question, “Where did this object come from?” The Object-Flow Virtual Machine, which we have proposed in previous work, tracks the flow of objects to answer precisely such questions, but this VM does not provide dedicated debugging support to explore faulty programs. In this paper we present a novel debugger, called Compass, to navigate between conventional run-time stack-oriented control flow views and object flows. Compass enables a developer to effectively navigate from an object contributing to an error back-in-time through all the code that has touched the object. We present the design and implementation of Compass, and we demonstrate how flow-centric, back-in-time debugging can be used to effectively locate the source of hard-to-find bugs.

Reducing the critical particle diameter in (highly) asymmetric sieve-based lateral displacement devices.

PubMed

Dijkshoorn, J P; Schutyser, M A I; Sebris, M; Boom, R M; Wagterveld, R M

2017-10-26

Deterministic lateral displacement technology was originally developed in the realm of microfluidics, but has potential for larger scale separation as well. In our previous studies, we proposed a sieve-based lateral displacement device inspired on the principle of deterministic lateral displacement. The advantages of this new device is that it gives a lower pressure drop, lower risk of particle accumulation, higher throughput and is simpler to manufacture. However, until now this device has only been investigated for its separation of large particles of around 785 µm diameter. To separate smaller particles, we investigate several design parameters for their influence on the critical particle diameter. In a dimensionless evaluation, device designs with different geometry and dimensions were compared. It was found that sieve-based lateral displacement devices are able to displace particles due to the crucial role of the flow profile, despite of their unusual and asymmetric design. These results demonstrate the possibility to actively steer the velocity profile in order to reduce the critical diameter in deterministic lateral displacement devices, which makes this separation principle more accessible for large-scale, high throughput applications.

Improved crystalline quality of AlN epitaxial layer on sapphire by introducing TMGa pulse flow into the nucleation stage

NASA Astrophysics Data System (ADS)

Wu, Hualong; Wang, Hailong; Chen, Yingda; Zhang, Lingxia; Chen, Zimin; Wu, Zhisheng; Wang, Gang; Jiang, Hao

2018-05-01

The crystalline quality of AlN epitaxial layers on sapphire substrates was improved by introducing trimethylgallium (TMGa) pulse flow into the growth of AlN nucleation layers. It was found that the density of both screw- and edge-type threading dislocations could be significantly reduced by introducing the TMGa pulse flow. With increasing TMGa pulse flow times, the lateral correlation length (i.e. the grain size) increases and the strain in the AlN epilayers changes from tensile state to compressive state. Unstrained AlN with the least dislocations and a smooth surface was obtained by introducing 2-times TMGa pulse flow. The crystalline improvement is attributed to enhanced lateral growth and improved crystalline orientation by the TMGa pulse flow.

Variability of Rheotaxis Behaviors in Larval Bullfrogs Highlights Species Diversity in Lateral Line Function

PubMed Central

Brown, Erika E. A.

2016-01-01

The morphology and distribution of lateral line neuromasts vary between ecomorphological types of anuran tadpoles, but little is known about how this structural variability contributes to differences in lateral-line mediated behaviors. Previous research identified distinct differences in one such behavior, positive rheotaxis towards the source of a flow, in two tadpole species, the African clawed frog (Xenopus laevis; type 1) and the American bullfrog (Rana catesbeiana; type 4). Because these two species had been tested under different flow conditions, we re-evaluated these findings by quantifying flow-sensing behaviors of bullfrog tadpoles in the same flow field in which X. laevis tadpoles had been tested previously. Early larval bullfrog tadpoles were exposed to flow in the dark, in the presence of a discrete light cue, and after treatment with the ototoxin gentamicin. In response to flow, tadpoles moved downstream, closer to a side wall, and higher in the water column, but they did not station-hold. Tadpoles exhibited positive rheotaxis, but with long latencies, low to moderate accuracy, and considerable individual variability. This is in contrast to the robust, stereotyped station-holding and accurate rheotaxis of X. laevis tadpoles. The presence of a discrete visual cue and gentamicin treatment altered spatial positioning and disrupted rheotaxis in both tadpole species. Species differences in lateral-line mediated behaviors may reflect differences in neuromast number and distribution, life history, or perceptual salience of other environmental cues. PMID:27870909

Analytical method for predicting the pressure distribution about a nacelle at transonic speeds

NASA Technical Reports Server (NTRS)

Keith, J. S.; Ferguson, D. R.; Merkle, C. L.; Heck, P. H.; Lahti, D. J.

1973-01-01

The formulation and development of a computer analysis for the calculation of streamlines and pressure distributions around two-dimensional (planar and axisymmetric) isolated nacelles at transonic speeds are described. The computerized flow field analysis is designed to predict the transonic flow around long and short high-bypass-ratio fan duct nacelles with inlet flows and with exhaust flows having appropriate aerothermodynamic properties. The flow field boundaries are located as far upstream and downstream as necessary to obtain minimum disturbances at the boundary. The far-field lateral flow field boundary is analytically defined to exactly represent free-flight conditions or solid wind tunnel wall effects. The inviscid solution technique is based on a Streamtube Curvature Analysis. The computer program utilizes an automatic grid refinement procedure and solves the flow field equations with a matrix relaxation technique. The boundary layer displacement effects and the onset of turbulent separation are included, based on the compressible turbulent boundary layer solution method of Stratford and Beavers and on the turbulent separation prediction method of Stratford.

Improved analysis of transient temperature data from permanent down-hole gauges (PDGs)

NASA Astrophysics Data System (ADS)

Zhang, Yiqun; Zheng, Shiyi; Wang, Qi

2017-08-01

With the installation of permanent down-hole gauges (PDGs) during oil field development, large volumes of high resolution and continuous down-hole information are obtainable. The interpretation of these real-time temperature and pressure data can optimize well performance, provide information about the reservoir and continuously calibrate the reservoir model. Although the dynamic temperature data have been interpreted in practice to predict flow profiling and provide characteristic information of the reservoir, almost all of the approaches rely on established non-isothermal models which depend on thermodynamic parameters. Another problem comes from the temperature transient analysis (TTA), which is underutilized compared with pressure transient analysis (PTA). In this study, several model-independent methods of TTA were performed. The entire set of PDG data consists of many flow events. By utilizing the wavelet transform, the exact points of flow-rate changes can be located. The flow regime changes, for example, from early time linear flow to later time pseudo-radial flow, among every transient period with constant flow-rate. For the early time region (ETR) that is caused by flow-rate change operations, the TTA, along with the PTA can greatly reduce the uncertainties in flow regime diagnosis. Then, the temperature variations during ETR were examined to infer the true reservoir temperature history, and the relationships between the wavelet detailed coefficients and the flow-rate changes were analysed. For the scenarios with constant reservoir-well parameters, the detailed flow-rate history can be generated by calculating the coefficient of relationship in advance. For later times, the flow regime changes to pseudo-radial flow. An analytical solution was introduced to describe the sand-face temperature. The formation parameters, such as permeability and skin factor, were estimated with the previously calculated flow-rate. It is necessary to analyse temperature variation to overcome data limitation problems when information from other down-hole tools (e.g. expensive but unstable flow meters) is insufficient. This study shows the success in wellbore storage regime diagnosis, flow-rate history reconstruction, and formation parameters estimation using transient temperature data.

Detection of H5 and H7 highly pathogenic avian influenza virus with lateral flow devices: performance with healthy, sick and dead chickens

USDA-ARS?s Scientific Manuscript database

Rapid detection of highly pathogenic avian influenza virus (HPAIV) in the field is critical for effective disease control and to differentiate it from other diseases, such as Newcastle disease. Lateral flow devices (LFD) are commercially available and provide a fast, highly specific, on-site test fo...

Flow visualization of lateral jet injection into swirling crossflow

NASA Technical Reports Server (NTRS)

Ferrell, G. B.; Aoki, K.; Lilley, D. G.

1985-01-01

Flow visualization experiments have been conducted to characterize the time-mean flowfield of a deflected turbulent jet in a confining cylindrical crossflow. Jet-to-crossflow velocity ratios of 2, 4, and 6 were investigated, under crossflow inlet swirler vane angles of 0 (swirler removed), 45 and 70 degrees. Smoke, neutrally-buoyant helium-filled soap bubbles, and multi-spark flow visualization were employed to highlight interesting features of the deflected jet, as well as the trajectory and spread pattern of the jet. Gross flowfield characterization was obtained for a range of lateral jet-to-crossflow velocity ratios and a range of inlet swirl strengths in the main flow. The flow visualization results agree well with the measurements obtained elsewhere with the six-orientation single hot-wire method.

Focusing and alignment of erythrocytes in a viscoelastic medium

NASA Astrophysics Data System (ADS)

Go, Taesik; Byeon, Hyeokjun; Lee, Sang Joon

2017-01-01

Viscoelastic fluid flow-induced cross-streamline migration has recently received considerable attention because this process provides simple focusing and alignment over a wide range of flow rates. The lateral migration of particles depends on the channel geometry and physicochemical properties of particles. In this study, digital in-line holographic microscopy (DIHM) is employed to investigate the lateral migration of human erythrocytes induced by viscoelastic fluid flow in a rectangular microchannel. DIHM provides 3D spatial distributions of particles and information on particle orientation in the microchannel. The elastic forces generated in the pressure-driven flows of a viscoelastic fluid push suspended particles away from the walls and enforce erythrocytes to have a fixed orientation. Blood cell deformability influences the lateral focusing and fixed orientation in the microchannel. Different from rigid spheres and hardened erythrocytes, deformable normal erythrocytes disperse from the channel center plane, as the flow rate increases. Furthermore, normal erythrocytes have a higher angle of inclination than hardened erythrocytes in the region near the side-walls of the channel. These results may guide the label-free diagnosis of hematological diseases caused by abnormal erythrocyte deformability.

Vertebrate Left-Right Asymmetry: What Can Nodal Cascade Gene Expression Patterns Tell Us?

PubMed Central

Schweickert, Axel; Ott, Tim; Kurz, Sabrina; Tingler, Melanie; Maerker, Markus; Fuhl, Franziska; Blum, Martin

2017-01-01

Laterality of inner organs is a wide-spread characteristic of vertebrates and beyond. It is ultimately controlled by the left-asymmetric activation of the Nodal signaling cascade in the lateral plate mesoderm of the neurula stage embryo, which results from a cilia-driven leftward flow of extracellular fluids at the left-right organizer. This scenario is widely accepted for laterality determination in wildtype specimens. Deviations from this norm come in different flavors. At the level of organ morphogenesis, laterality may be inverted (situs inversus) or non-concordant with respect to the main body axis (situs ambiguus or heterotaxia). At the level of Nodal cascade gene activation, expression may be inverted, bilaterally induced, or absent. In a given genetic situation, patterns may be randomized or predominantly lacking laterality (absence or bilateral activation). We propose that the distributions of patterns observed may be indicative of the underlying molecular defects, with randomizations being primarily caused by defects in the flow-generating ciliary set-up, and symmetrical patterns being the result of impaired flow sensing, on the left, the right, or both sides. This prediction, the reasoning of which is detailed in this review, pinpoints functions of genes whose role in laterality determination have remained obscure. PMID:29367579

High quality optical microangiography of ocular microcirculation and measurement of total retinal blood flow in mouse eye

NASA Astrophysics Data System (ADS)

Zhi, Zhongwei; Yin, Xin; Dziennis, Suzan; Alpers, Charles E.; Wang, Ruikang K.

2013-03-01

Visualization and measurement of retinal blood flow (RBF) is important to the diagnosis and management of different eye diseases, including diabetic retinopathy. Optical microangiography (OMAG) is developed for generating 3D dynamic microcirculation image and later refined into ultra-high sensitive OMAG (UHS-OMAG) for true capillary vessels imaging. Here, we present the application of OMAG imaging technique for visualization of depth-resolved vascular network within retina and choroid as well as measurement of total retinal blood flow in mice. A fast speed spectral domain OCT imaging system at 820nm with a line scan rate of 140 kHz was developed to image mouse posterior eye. By applying UHS-OMAG scanning protocol and processing algorithm, we achieved true capillary level imaging of retina and choroid vasculature in mouse eye. The vascular pattern within different retinal layers and choroid was presented. An en face Doppler OCT approach [1] without knowing Doppler angle was adopted for the measurement of total retinal blood flow. The axial blood flow velocity is measured in an en face plane by raster scanning and the flow is calculated by integrating over the vessel area of the central retinal artery.

Development of levees on deep-sea channels: Insights from high-resolution AUV exploration of the Lucia Chica system, offshore central California

NASA Astrophysics Data System (ADS)

Maier, K. L.; Fildani, A.; Romans, B.; Paull, C. K.; McHargue, T.; Graham, S. A.; Caress, D. W.

2010-12-01

The Lucia Chica, a tributary channel system of the Lucia Canyon, offshore central California, was imaged using the Monterey Bay Aquarium Research Institute’s (MBARI) Autonomous Underwater Vehicle (AUV) in order to investigate seafloor and subsurface morphologies associated with low-relief submarine channels. In larger, previously investigated seafloor channel-levee systems, initial deposits are either eroded, compacted, or below the resolution of available imaging. In this dataset from the Lucia Chica, the unprecedented high-resolution multibeam bathymetry (1 m lateral resolution) and chirp sub-bottom profiles (11 cm vertical resolution) reveal a highly irregular seafloor with scours, depressions, and discontinuous low-relief conduits over an area of ~70 km2. Sediment packages associated with channels, levees, and deposits related to less confined flows are correlated between chirp profiles and with the multibeam bathymetric image to determine the stratigraphic evolution of the Lucia Chica and the sequence of channel-levee development. In the Lucia Chica, channels appear to have initiated as trains of scours that eventually coalesced into continuous channel thalwegs carved by erosional turbidity currents. Channel incision and stepped lateral migration led to the development of terraces, complex levee stratigraphy, and distinct morphologies associated with inner and outer bends of sinuous channels. The inner bend levee stratigraphy indicates that the channel position migrated in discrete shifts, as opposed to continuous channel migration associated with lateral accretion. Discrete levee packages, formed from flow-stripped turbidity currents, later infilled abandoned portions of the channel and overbank areas. While processes of initial channel and levee development are well established in fluvial settings, detailed examples are lacking for deep-sea systems. These results highlight the differences in initiation between submarine channel systems, their fluvial counterparts, and larger submarine channel-levee systems imaged only with lower-resolution technologies. High-resolution imaging and detailed mapping made possible by cutting-edge oceanographic technology provide an unprecedented examination of deep-water channel-levee morphology and improve understanding of deep-water channel migration and levee development.

A process-oriented hydro-biogeochemical model enabling simulation of gaseous carbon and nitrogen emissions and hydrologic nitrogen losses from a subtropical catchment.

PubMed

Zhang, Wei; Li, Yong; Zhu, Bo; Zheng, Xunhua; Liu, Chunyan; Tang, Jialiang; Su, Fang; Zhang, Chong; Ju, Xiaotang; Deng, Jia

2018-03-01

Quantification of nitrogen losses and net greenhouse gas (GHG) emissions from catchments is essential for evaluating the sustainability of ecosystems. However, the hydrologic processes without lateral flows hinder the application of biogeochemical models to this challenging task. To solve this issue, we developed a coupled hydrological and biogeochemical model, Catchment Nutrients Management Model - DeNitrification-DeComposition Model (CNMM-DNDC), to include both vertical and lateral mass flows. By incorporating the core biogeochemical processes (including decomposition, nitrification, denitrification and fermentation) of the DNDC into the spatially distributed hydrologic framework of the CNMM, the simulation of lateral water flows and their influences on nitrogen transportation can be realized. The CNMM-DNDC was then calibrated and validated in a small subtropical catchment belonged to Yanting station with comprehensive field observations. Except for the calibration of water flows (surface runoff and leaching water) in 2005, stream discharges of water and nitrate in 2007, the model validations of soil temperature, soil moisture, crop yield, water flows in 2006 and associated nitrate loss, fluxes of methane, ammonia, nitric oxide and nitrous oxide, and stream discharges of water and nitrate in 2008 were statistically in good agreement with the observations. Meanwhile, our initial simulation of the catchment showed scientific predictions. For instance, it revealed the following: (i) dominant ammonia volatilization among the losses of nitrogenous gases (accounting for 11-21% of the applied annual fertilizer nitrogen in croplands); (ii) hotspots of nitrate leaching near the main stream; and (iii) a net GHG sink function of the catchment. These results implicate the model's promising capability of predicting ecosystem productivity, hydrologic nitrogen loads, losses of gaseous nitrogen and emissions of GHGs, which could be used to provide strategies for establishing sustainable catchments. In addition, the model's capability would be further proved by applying in other catchments with different backgrounds. Copyright © 2017. Published by Elsevier B.V.

Sample stream distortion modeled in continuous-flow electrophoresis

NASA Technical Reports Server (NTRS)

Rhodes, P. H.

1979-01-01

Buoyancy-induced disturbances in an electrophoresis-type chamber were investigated. Five tracer streams (latex) were used to visualize the flows while a nine-thermistor array sensed the temperature field. The internal heating to the chamber was provided by a 400 Hz electrical field. Cooling to the chamber was provided on the front and back faces and, in addition, on both chamber side walls. Disturbances to the symmetric base flow in the chamber occurred in the broad plane of the chamber and resulted from the formation of lateral and axial temperature gradients. The effect of these gradients was to retard or increase local flow velocities at different positions in the chamber cross section, which resulted in lateral secondary flows being induced in the broad plane of the chamber. As the adverse temperature gradients increased in magnitude, the critical Rayleigh number was approached and reverse (separated) flow became apparent, which, subsequently, led to the onset of time variant secondary flows.

Magnetic Control of Lateral Migration of Ellipsoidal Microparticles in Microscale Flows

NASA Astrophysics Data System (ADS)

Zhou, Ran; Sobecki, Christopher A.; Zhang, Jie; Zhang, Yanzhi; Wang, Cheng

2017-08-01

Precise manipulations of nonspherical microparticles by shape have diverse applications in biology and biomedical engineering. Here, we study lateral migration of ellipsoidal paramagnetic microparticles in low-Reynolds-number flows under uniform magnetic fields. We show that magnetically induced torque alters the rotation dynamics of the particle and results in shape-dependent lateral migration. By adjusting the direction of the magnetic field, we demonstrate versatile control of the symmetric and asymmetric rotation of the particles, thereby controlling the direction of the particle's lateral migration. The particle rotations are experimentally measured, and their symmetry or asymmetry characteristics agree well with the prediction from a simple theory. The lateral migration mechanism is found to be valid for nonmagnetic particles suspended in a ferrofluid. Finally, we demonstrate shape-based sorting of microparticles by exploiting the proposed migration mechanism.

Effects of Soluble Surfactant on Lateral Migration of a Bubble in a Shear Flow

NASA Astrophysics Data System (ADS)

Muradoglu, Metin; Tryggvason, Gretar

2014-11-01

Motivated by the recent experimental study of Takagi et al. (2008), direct numerical simulations are performed to examine effects of soluble surfactant on the lateral migration of a deformable bubble in a pressure-driven channel flow. The interfacial and bulk surfactant concentration evolution equations are solved fully coupled with the incompressible Navier-Stokes equations. A non-linear equation of state is used to relate interfacial surface tension to surfactant concentration at the interface. A multiscale method is developed to handle the mass exchange between the interface and bulk fluid at high Peclet numbers, using a boundary-layer approximation next to the bubble and a relatively coarse grid for the rest of the flow. It is found that the surfactant induced Marangoni stresses can dominate over the shear-induced lift force and thus alter the behavior of the bubble completely, i.e., the contaminated bubble drifts away from the channel wall and stabilizes at the center of the channel in contrast with the corresponding clean bubble that drifts toward the wall and stabilizes near the wall. The Scientific and Technical Research Council of Turkey (TUBITAK), Grant 112M181 and Turkish Academy of Sciences (TUBA).

Denitrification in the Mississippi River network controlled by flow through river bedforms

USGS Publications Warehouse

Gomez-Velez, Jesus D.; Harvey, Judson W.; Cardenas, M. Bayani; Kiel, Brian

2015-01-01

Increasing nitrogen concentrations in the world’s major rivers have led to over-fertilization of sensitive downstream waters. Flow through channel bed and bank sediments acts to remove riverine nitrogen through microbe-mediated denitrification reactions. However, little is understood about where in the channel network this biophysical process is most efficient, why certain channels are more effective nitrogen reactors, and how management practices can enhance the removal of nitrogen in regions where water circulates through sediment and mixes with groundwater - hyporheic zones. Here we present numerical simulations of hyporheic flow and denitrification throughout the Mississippi River network using a hydrogeomorphic model. We find that vertical exchange with sediments beneath the riverbed in hyporheic zones, driven by submerged bedforms, has denitrification potential that far exceeds lateral hyporheic exchange with sediments alongside river channels, driven by river bars and meandering banks. We propose that geomorphic differences along river corridors can explain why denitrification efficiency varies between basins in the Mississippi River network. Our findings suggest that promoting the development of permeable bedforms at the streambed - and thus vertical hyporheic exchange - would be more effective at enhancing river denitrification in large river basins than promoting lateral exchange through induced channel meandering.

Acoustic cavity transducers for the manipulation of cells and biomolecules

NASA Astrophysics Data System (ADS)

Tovar, Armando; Patel, Maulik; Lee, Abraham P.

2010-02-01

A novel fluidic actuator that is simple to fabricate, integrate, and operate is demonstrated for use within microfluidic systems. The actuator is designed around the use of trapped air bubbles in lateral cavities and the resultant acoustic streaming generated from an outside acoustic energy source. The orientation of the lateral cavities to the main microchannel is used to control the bulk fluid motion within the device. The first order flow generated by the oscillating bubble is used to develop a pumping platform that is capable of driving fluid within a chip. This pump is integrated into a recirculation immunoassay device for enhanced biomolecule binding through fluid flow for convection limited transport. The recirculation system showed an increase in binding site concentration when compared with traditional passive and flow-through methods. The acoustic cavity transducer has also been demonstrated for application in particle switching. Bursts of acoustic energy are used to generate a second order streaming pattern near the cavity interface to drive particles away or towards the cavity. The use of this switching mechanism is being extended to the application of sorting cells and other particles within a microfluidic system.

Simultaneous ultrasound and photoacoustics based flow cytometry

NASA Astrophysics Data System (ADS)

Gnyawali, Vaskar; Strohm, Eric M.; Tsai, Scott S. H.; Kolios, Michael C.

2018-04-01

We have developed a flow cytometer based on simultaneous detection of ultrasound and photoacoustic waves from individual particles/cells flowing in a microfluidic channel. Our polydimethylsiloxane (PDMS) based hydrodynamic 3-dimensional (3D) flow-focusing microfluidic device contains a cross-junction channel, a micro-needle (ID 100 μm and OD 200 μm) insert, and a 3D printed frame to hold and align a high frequency (center frequency 375 MHz) ultrasound transducer. The focused flow passes through a narrow focal zone with lateral and axial focal lengths of 6-8 μm and 15-20 μm, respectively. Both the lateral and axial alignments are achieved by screwing the transducer to the frame onto the PDMS device. Individual particles pass through an interrogation zone in the microfluidic channel with a collinearly aligned ultrasound transducer and a focused 532 nm wavelength laser beam. The particles are simultaneously insonified by high-frequency ultrasound and irradiated by a laser beam. The ultrasound backscatter and laser generated photoacoustic waves are detected for each passing particle. The backscattered ultrasound and photoacoustic signal are strongly dependent on the size, morphology, mechanical properties, and material properties of the flowing particles; these parameters can be extracted by analyzing unique features in the power spectrum of the signals. Frequencies less than 100 MHz do not have these unique spectral signatures. We show that we can reliably distinguish between different particles in a sample using the acoustic-based flow cytometer. This technique, when extended to biomedical applications, allows us to rapidly analyze the spectral signatures from individual single cells of a large cell population, with applications towards label-free detection and characterization of healthy and diseased cells.

Earth observation based assessment of the water production and water consumption of Nile Basin agro-ecosystems

USGS Publications Warehouse

Bastiaanssen, Wim G.M.; Karimi, Poolad; Rebelo, Lisa-Maria; Duan, Zheng; Senay, Gabriel; Muthuwatte, Lal; Smakhtin, Vladimir

2014-01-01

The increasing competition for water resources requires a better understanding of flows, fluxes, stocks, and the services and benefits related to water consumption. This paper explains how public domain Earth Observation data based on Moderate Resolution Imaging Spectroradiometer (MODIS), Second Generation Meteosat (MSG), Tropical Rainfall Measurement Mission (TRMM) and various altimeter measurements can be used to estimate net water production (rainfall (P) > evapotranspiration (ET)) and net water consumption (ET > P) of Nile Basin agro-ecosystems. Rainfall data from TRMM and the Famine Early Warning System Network (FEWS-NET) RainFall Estimates (RFE) products were used in conjunction with actual evapotranspiration from the Operational Simplified Surface Energy Balance (SSEBop) and ETLook models. Water flows laterally between net water production and net water consumption areas as a result of runoff and withdrawals. This lateral flow between the 15 sub-basins of the Nile was estimated, and partitioned into stream flow and non-stream flow using the discharge data. A series of essential water metrics necessary for successful integrated water management are explained and computed. Net water withdrawal estimates (natural and humanly instigated) were assumed to be the difference between net rainfall (Pnet) and actual evapotranspiration (ET) and some first estimates of withdrawals—without flow meters—are provided. Groundwater-dependent ecosystems withdraw large volumes of groundwater, which exceed water withdrawals for the irrigation sector. There is a strong need for the development of more open-access Earth Observation databases, especially for information related to actual ET. The fluxes, flows and storage changes presented form the basis for a global framework to describe monthly and annual water accounts in ungauged river basins.

Development of a Smartphone-based reading system for lateral flow immunoassay.

PubMed

Lee, Sangdae; Kim, Giyoung; Moon, Jihea

2014-11-01

This study was conducted to develop and evaluate the performance of the Smartphone-based reading system for the lateral flow immunoassay (LFIA). Smartphone-based reading system consists of a Samsung Galaxy S2 Smartphone, Smartphone application, and a LFIA reader. LFIA reader is composed of the close-up lens with a focal length up to 30 mm, white LED light, lithium polymer battery, and main body. The Smartphone application for image acquisition and data analysis was developed on the Android platform. The standard curve was obtained by plotting the measured P(T)/P(c) or A(T)/A(c) ratio versus Salmonella standard concentration. The mean, standard deviation (SD), recovery, and relative standard deviation (RSD) were also calculated using additional experimental results. These data were compared with that obtained from the benchtop LFIA reader. The LOD in both systems was observed with 10(6) CFU/mL. The results show high accuracy and good reproducibility with a RSD less than 10% in the range of 10(6) to 10(9) CFU/mL. Due to the simple structure, good sensitivity, and high accuracy of the Smartphone-based reading system, this system can be substituted for the benchtop LFIA reader for point-of-care medical diagnostics.

Lateral Migration and Rotational Motion of Elliptic Particles in Planar Poiseuille Flow

NASA Technical Reports Server (NTRS)

Qi, Dewei; Luo, Li-Shi; Aravamuthan, Raja; Strieder, William; Bushnell, Dennis M. (Technical Monitor)

2002-01-01

Simulations of elliptic particulate suspensions in the planar Poiseuille flow are performed by using the lattice Boltzmann equation. Effects of the multi-particle on the lateral migration and rotational motion of both neutrally and non-neutrally buoyant elliptic particles are investigated. Low and intermediate total particle volume fraction f(sub a) = 13%, 15%, and 40% are considered in this work.

Goldfish and oscars have comparable responsiveness to dipole stimuli

NASA Astrophysics Data System (ADS)

Nauroth, Ines Eva; Mogdans, Joachim

2009-12-01

The relative roles of the fish lateral line and inner ear for the perception of hydrodynamic stimuli are poorly investigated. Here, we studied responsiveness to a 100 Hz vibrating sphere (dipole stimulus) of goldfish and oscars, two species that differ in peripheral lateral line morphology, inner ear morphology, mechanical linkage between inner ear and swim bladder, and inner ear sensitivity. We measured unconditioned dipole-evoked changes in breathing activity in still water and in the presence of a 5-cm s-1 background flow. In still water, individuals from both species responded to sound pressure levels (SPLs) between 92 and 109 dB SPL re 1 μPaRMS. Responsiveness was not affected by background flow or by temporary inactivation of the lateral line. The data suggest that fish with different lateral line and inner ear morphologies have similar sensitivities to vibrating sphere stimuli and can detect and respond to dipole sources equally well in still water and in moderate background flows. Moreover, behavioral responses were not dependent on a functional lateral line, suggesting that in this type of experiment, the inner ear is the dominant sense organ for the perception of hydrodynamic stimuli.

Marked Increase in Flow Velocities During Deep Expiration: A Duplex Doppler Sign of Celiac Artery Compression Syndrome

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erden, Ayse; Yurdakul, Mehmet; Cumhur, Turhan

1999-07-15

Symptoms of chronic mesenteric ischemia develop when the celiac artery is constricted by the median arcuate ligament of the diaphragm. Lateral aortography is the primary modality for diagnosing ligamentous compression of the celiac artery. However, duplex Doppler sonography performed during deep expiration can cause a marked increase in flow velocities at the compressed region of the celiac artery and suggest the diagnosis of celiac arterial constriction due to the diaphragmatic ligament. RID='''' ID='''' Correspondence to: A. Erden, M.D., Hafta sokak. 23/6, Gaziosmanpasa, 06700 Ankara, Turkey.

Effects of Structural Flexibility on Motorcycle Straight Running Stability by using Energy Flow Method

NASA Astrophysics Data System (ADS)

Marumo, Yoshitaka; Katayama, Tsuyoshi

This study uses the energy flow method to analyze how structural flexibility affects the motorcycle wobble and weave modes. Lateral bending of the front fork and torsion of the main frame affect the wobble mode stability. These are based on the gyroscopic effect of the front wheel in the steering motion by considering structural flexibility. At high speeds, lateral bending of the front fork and torsion of the rear swing arm more significantly affect the weave mode stability. These are primarily due to the phase changes of the external force generated by the yaw rate in the lateral motion. The phase change of the yaw rate force in the lateral motion originates from the phase change of the tire side forces.

A three-dimensional stratigraphic model for aggrading submarine channels based on laboratory experiments, numerical modeling, and sediment cores

NASA Astrophysics Data System (ADS)

Limaye, A. B.; Komatsu, Y.; Suzuki, K.; Paola, C.

2017-12-01

Turbidity currents deliver clastic sediment from continental margins to the deep ocean, and are the main driver of landscape and stratigraphic evolution in many low-relief, submarine environments. The sedimentary architecture of turbidites—including the spatial organization of coarse and fine sediments—is closely related to the aggradation, scour, and lateral shifting of channels. Seismic stratigraphy indicates that submarine, meandering channels often aggrade rapidly relative to lateral shifting, and develop channel sand bodies with high vertical connectivity. In comparison, the stratigraphic architecture developed by submarine, braided is relatively uncertain. We present a new stratigraphic model for submarine braided channels that integrates predictions from laboratory experiments and flow modeling with constraints from sediment cores. In the laboratory experiments, a saline density current developed subaqueous channels in plastic sediment. The channels aggraded to form a deposit with a vertical scale of approximately five channel depths. We collected topography data during aggradation to (1) establish relative stratigraphic age, and (2) estimate the sorting patterns of a hypothetical grain size distribution. We applied a numerical flow model to each topographic surface and used modeled flow depth as a proxy for relative grain size. We then conditioned the resulting stratigraphic model to observed grain size distributions using sediment core data from the Nankai Trough, offshore Japan. Using this stratigraphic model, we establish new, quantitative predictions for the two- and three-dimensional connectivity of coarse sediment as a function of fine-sediment fraction. Using this case study as an example, we will highlight outstanding challenges in relating the evolution of low-relief landscapes to the stratigraphic record.

Assessment of sacrococcygeal pressure ulcers using diffuse correlation spectroscopy

NASA Astrophysics Data System (ADS)

Diaz, David; Lafontant, Alec; Neidrauer, Michael; Weingarten, Michael S.; DiMaria-Ghalili, Rose Ann; Fried, Guy W.; Rece, Julianne; Lewin, Peter A.; Zubkov, Leonid

2016-03-01

Microcirculation is essential for proper supply of oxygen and nutritive substances to the biological tissue and the removal of waste products of metabolism. The determination of microcirculatory blood flow (mBF) is therefore of substantial interest to clinicians for assessing tissue health; particularly in pressure ulceration and suspected deep tissue injury. The goal of this pilot clinical study was to assess deep-tissue pressure ulceration by non-invasively measuring mBF using Diffuse Correlation Spectroscopy (DCS). DCS provides information about the flow of red blood cells in the capillary network by measuring the temporal autocorrelation function of scattering light intensity. A novel optical probe was developed in order to obtain measurements under the load of the subject's body as pressure is applied (ischemia) and then released (reperfusion) on sacrococcygeal tissue in a hospital bed. Prior to loading measurements, baseline readings of the sacral region were obtained by measuring the subjects in a side-lying position. DCS measurements from the sacral region of twenty healthy volunteers have been compared to those of two patients who initially had similar non-blanchable redness. The temporal autocorrelation function of scattering light intensity of the patient whose redness later disappeared was similar to that of the average healthy subject. The second patient, whose redness developed into an advanced pressure ulcer two weeks later, had a substantial decrease in blood flow while under the loading position compared to healthy subjects. Preliminary results suggest the developed system may potentially predict whether non-blanchable redness will manifest itself as advanced ulceration or dissipate over time.

3D flow focusing for microfluidic flow cytometry with ultrasonics

NASA Astrophysics Data System (ADS)

Gnyawali, Vaskar; Strohm, Eric M.; Daghighi, Yasaman; van de Vondervoort, Mia; Kolios, Michael C.; Tsai, Scott S. H.

2015-11-01

We are developing a flow cytometer that detects unique acoustic signature waves generated from single cells due to interactions between the cells and ultrasound waves. The generated acoustic waves depend on the size and biomechanical properties of the cells and are sufficient for identifying cells in the medium. A microfluidic system capable of focusing cells through a 10 x 10 μm ultrasound beam cross section was developed to facilitate acoustic measurements of single cells. The cells are streamlined in a hydro-dynamically 3D focused flow in a 300 x 300 μm channel made using PDMS. 3D focusing is realized by lateral sheath flows and an inlet needle (inner diameter 100 μm). The accuracy of the 3D flow focusing is measured using a dye and detecting its localization using confocal microscopy. Each flowing cell would be probed by an ultrasound pulse, which has a center frequency of 375 MHz and bandwidth of 250 MHz. The same probe would also be used for recording the scattered waves from the cells, which would be processed to distinguish the physical and biomechanical characteristics of the cells, eventually identifying them. This technique has potential applications in detecting circulating tumor cells, blood cells and blood-related diseases.

Leading-edge effects on boundary-layer receptivity

NASA Technical Reports Server (NTRS)

Gatski, Thomas B.; Kerschen, Edward J.

1990-01-01

Numerical calculations are presented for the incompressible flow over a parabolic cylinder. The computational domain extends from a region upstream of the body downstream to the region where the Blasius boundary-layer solution holds. A steady mean flow solution is computed and the results for the scaled surface vorticity, surface pressure and displacement thickness are compared to previous studies. The unsteady problem is then formulated as a perturbation solution starting with and evolving from the mean flow. The response to irrotational time harmonic pulsation of the free-stream is examined. Results for the initial development of the velocity profile and displacement thickness are presented. These calculations will be extended to later times to investigate the initiation of instability waves within the boundary-layer.

Bluff-body drag reduction using a deflector

NASA Astrophysics Data System (ADS)

Fourrié, Grégoire; Keirsbulck, Laurent; Labraga, Larbi; Gilliéron, Patrick

2011-02-01

A passive flow control on a generic car model was experimentally studied. This control consists of a deflector placed on the upper edge of the model rear window. The study was carried out in a wind tunnel at Reynolds numbers based on the model height of 3.1 × 105 and 7.7 × 105. The flow was investigated via standard and stereoscopic particle image velocimetry, Kiel pressure probes and surface flow visualization. The aerodynamic drag was measured using an external balance and calculated using a wake survey method. Drag reductions up to 9% were obtained depending on the deflector angle. The deflector increases the separated region on the rear window. The results show that when this separated region is wide enough, it disrupts the development of the counter-rotating longitudinal vortices appearing on the lateral edges of the rear window. The current study suggests that flow control on such geometries should consider all the flow structures that contribute to the model wake flow.

VORSTAB: A computer program for calculating lateral-directional stability derivatives with vortex flow effect

NASA Technical Reports Server (NTRS)

Lan, C. Edward

1985-01-01

A computer program based on the Quasi-Vortex-Lattice Method of Lan is presented for calculating longitudinal and lateral-directional aerodynamic characteristics of nonplanar wing-body combination. The method is based on the assumption of inviscid subsonic flow. Both attached and vortex-separated flows are treated. For the vortex-separated flow, the calculation is based on the method of suction analogy. The effect of vortex breakdown is accounted for by an empirical method. A summary of the theoretical method, program capabilities, input format, output variables and program job control set-up are described. Three test cases are presented as guides for potential users of the code.

A uniform method for the simultaneous blood group phenotyping of Fya , Fyb , Jka , Jkb , S, s̅, P1, k applying lateral-flow technique.

PubMed

Caesar, A; Meyer, S; Trost, N; Neuenschwander, K; Geisen, C; Frey, B M; Gassner, C; Schwind, P

2018-02-01

A lateral flow assay for simultaneous blood group typing of ABO, RhD, C, E, c, e, Cw and K with stable end-point and without centrifugation is in routine use since several years (MDmulticard ® ). The typing of extended phenotype parameters belonging to the Duffy, Kidd, MNSs blood group systems and others, however, has not yet been demonstrated for this technique. Reliable detection of Fy x , a weak Fy b phenotype with a pronounced quantitative reduction of the number of Fy b antigens on the erythrocyte surface, remains a weakness of current serological blood grouping techniques. The performance characteristics of the following reagents were evaluated in donor and patient samples in lateral flow technology (MDmulticard ® ): Anti-Fy a , -Fy b , -Jk a , -Jk b , -S, -s̅, -P1 and -k. The sensitivity to detect Fy x was in addition evaluated with Fy x positive samples, which had been preselected by MALDI-TOF MS-based genotyping. All results obtained with the MDmulticard ® were in full accordance with those of the CE-certified reference products for all the eight reagent formulations used: Anti-Fy a , -Fy b , -Jk a , -Jk b , -S, -s̅, -P1 and -k. Also, all Fy x phenotypes of the selected population of 93 positive samples, originally identified by MALDI-TOF MS-based genotyping, were reliably detected by the lateral flow assay. Extended phenotype blood group parameters, including the serologically challenging Fy x phenotype, can be determined simultaneously, rapidly and accurately using the lateral flow (MDmulticard ® ) technology, even in cases when IgG class antibodies are the only source of diagnostic antibodies. © 2017 International Society of Blood Transfusion.

An ultra-sensitive monoclonal antibody-based fluorescent microsphere immunochromatographic test strip assay for detecting aflatoxin M1 in milk

USDA-ARS?s Scientific Manuscript database

A rapid lateral flow fluorescent microspheres immunochromatography test strip (FMs-ICTS) has been developed for the detection of aflatoxin M1 (AFM1) residues in milk. For this purpose, an ultra-sensitive anti-AFM1 monoclonal antibody (MAb) 1D3 was prepared and identified. The IC50 value of the MA...

Development of a lateral flow immunoassay for rapid field detection of the red imported fire ant, Solenopsis invicta (Hymenoptera: Formicidae)

USDA-ARS?s Scientific Manuscript database

The red imported fire ant, Solenopsis invicta, is an aggressive, highly invasive pest ant species from South America that has been introduced into North America, Asia and Australia. Quarantine efforts have been imposed in the United States to minimize the spread of the ant. There remains an acute ...

Modeling streamflow in a snow-dominated forest watershed using the Water Erosion Prediction Project (WEPP) model

Treesearch

A. Srivastava; J. Q. Wu; W. J. Elliot; E. S. Brooks; D. C. Flanagan

2017-01-01

The Water Erosion Prediction Project (WEPP) model was originally developed for hillslope and small watershed applications. Recent improvements to WEPP have led to enhanced computations for deep percolation, subsurface lateral flow, and frozen soil. In addition, the incorporation of channel routing has made the WEPP model well suited for large watersheds with perennial...

Developing Causal Understanding with Causal Maps: The Impact of Total Links, Temporal Flow, and Lateral Position of Outcome Nodes

ERIC Educational Resources Information Center

Jeong, Allan; Lee, Woon Jee

2012-01-01

This study examined some of the methodological approaches used by students to construct causal maps in order to determine which approaches help students understand the underlying causes and causal mechanisms in a complex system. This study tested the relationship between causal understanding (ratio of root causes correctly/incorrectly identified,…

Architectural features of the Kayenta formation (Lower Jurassic), Colorado Plateau, USA: relationship to salt tectonics in the Paradox Basin

NASA Astrophysics Data System (ADS)

Bromley, Michael H.

1991-09-01

Fluvial sandstones of the Kayenta Formation were analyzed using architectural element analysis. Paleocurrent trends, the distribution of lacustrine facies and local silcrete development indicate that synsedimentary movement of evaporites in the underlying Paradox Basin created an unstable basin floor beneath the Kayenta fluvial system. This instability resulted in deflection of fluvial axes, local basin development and local areas of interrupted fluvial deposition with eolian dunes. Paleocurrent trends in the Kayenta system reflect periodic interruptions of southwesterly flow. Salt migrating laterally out of a rim syncline into an adjacent salt anticline resulted in a rim syncline of slight topographic relief. The resulting basin was probably rapidly filled, allowing the resumption of southwesterly flow. Differential movement of salt (incipient solution collapse features (?)) resulted in the formation of small centripetal basins in which playa mudstones formed. A laterally extensive resistant ledge underlies a horizontal surface, suggestive of deflation to the water table of an exposed section of valley fill. A channel scour in the top of one of these surfaces has margins much steeper ( > 60°) than the angle of repose for unconsolidated sand. Early cementation of the exposed floodplain could account for this resistance.

Subsurface Hydrologic Processes Revealed by Time-lapse GPR in Two Contrasting Soils in the Shale Hills CZO

NASA Astrophysics Data System (ADS)

Guo, L.; Lin, H.; Nyquist, J.; Toran, L.; Mount, G.

2017-12-01

Linking subsurface structures to their functions in determining hydrologic processes, such as soil moisture dynamics, subsurface flow patterns, and discharge behaviours, is a key to understanding and modelling hydrological systems. Geophysical techniques provide a non-invasive approach to investigate this form-function dualism of subsurface hydrology at the field scale, because they are effective in visualizing subsurface structure and monitoring the distribution of water. In this study, we used time-lapse ground-penetrating radar (GPR) to compare the hydrologic responses of two contrasting soils in the Shale Hills Critical Zone Observatory. By integrating time-lapse GPR with artificial water injection, we observed distinct flow patterns in the two soils: 1) in the deep Rushtown soil (over 1.5 m depth to bedrock) located in a concave hillslope, a lateral preferential flow network extending as far as 2 m downslope was identified above a less permeable layer and via a series of connected macropores; whereas 2) in the shallow Weikert soil ( 0.3 m depth to saprock) located in a planar hillslope, vertical infiltration into the permeable fractured shale dominated the flow field, while the development of lateral preferential flow along the hillslope was restrained. At the Weikert soil site, the addition of brilliant blue dye to the water injection followed by in situ excavation supported GPR interpretation that only limited lateral preferential flow formed along the soil-saprock interface. Moreover, seasonally repeated GPR surveys indicated different patterns of profile moisture distribution in the two soils that in comparison with the dry season, a dense layer within the BC horizon in the deep Rushtown soil prevented vertical infiltration in the wet season, leading to the accumulation of soil moisture above this layer; whereas, in the shallow Weikert soil, water infiltrated into saprock in wet seasons, building up water storage within the fractured bedrock (i.e., the rock moisture). Results of this study demonstrated the strong interplay between soil structures and subsurface hydrologic behaviors, and time-lapse GPR is an effective method to establish such a relationship under the field conditions.

Film cooling from inclined cylindrical holes using large eddy simulations

NASA Astrophysics Data System (ADS)

Peet, Yulia V.

2006-12-01

The goal of the present study is to investigate numerically the physics of the flow, which occurs during the film cooling from inclined cylindrical holes, Film cooling is a technique used in gas turbine industry to reduce heat fluxes to the turbine blade surface. Large Eddy Simulation (LES) is performed modeling a realistic film cooling configuration, which consists of a large stagnation-type reservoir, feeding an array of discrete cooling holes (film holes) flowing into a flat plate turbulent boundary layer. Special computational methodology is developed for this problem, involving coupled simulations using multiple computational codes. A fully compressible LES code is used in the area above the flat plate, while a low Mach number LES code is employed in the plenum and film holes. The motivation for using different codes comes from the essential difference in the nature of the flow in these different regions. Flowfield is analyzed inside the plenum, film hole and a crossflow region. Flow inside the plenum is stagnating, except for the region close to the exit, where it accelerates rapidly to turn into the hole. The sharp radius of turning at the trailing edge of the plenum pipe connection causes the flow to separate from the downstream wall of the film hole. After coolant injection occurs, a complex flowfield is formed consisting of coherent vortical structures responsible for bringing hot crossflow fluid in contact with the walls of either the film hole or the blade, thus reducing cooling protection. Mean velocity and turbulent statistics are compared to experimental measurements, yielding good agreement for the mean flowfield and satisfactory agreement for the turbulence quantities. LES results are used to assess the applicability of basic assumptions of conventional eddy viscosity turbulence models used with Reynolds-averaged (RANS) approach, namely the isotropy of an eddy viscosity and thermal diffusivity. It is shown here that these assumptions do not hold for the film cooling flows. Comparison of film cooling effectiveness with experiments shows fair agreement for the centerline and laterally-averaged effectiveness. Lateral growth of the jet as judged from the lateral distribution of effectiveness is predicted correctly.

Microfabrication of IPMC cilia for bio-inspired flow sensing

NASA Astrophysics Data System (ADS)

Lei, Hong; Li, Wen; Tan, Xiaobo

2012-04-01

As the primary flow sensing organ for fishes, the lateral line system plays a critical role in fish behavior. Analogous to its biological counterpart, an artificial lateral line system, consisting of arrays of micro flow sensors, is expected to be instrumental in the navigation and control of underwater robots. In this paper we investigate the microfabrication of ionic polymer-metal composite (IPMC) cilia for the purpose of flow sensing. While existing macro- and microfabrication methods for IPMCs have predominantly focused on planar structures, we propose a device where micro IPMC beams stand upright on a substrate to effectively interact with the flow. Challenges in the casting of 3D Nafion structure and selective formation of electrodes are discussed, and potential solutions for addressing these challenges are presented together with preliminary microfabrication results.

Coupled heat and silica transport associated with dike intrusion into sedimentary rock: effects on isotherm location and permeability evolution

NASA Astrophysics Data System (ADS)

Dutrow, Barbara L.; Travis, Bryan J.; Gable, Carl W.; Henry, Darrell J.

2001-11-01

An 11-meter-wide alkalic monchiquite dike recovered from the subsurface of Louisiana has produced a metasomatic aureole in the adjacent interbedded carbonate mudstones and siltstones. The asymmetric contact aureole, which extends nearly 6 m above and 4 m below the intrusion, contains the metamorphic minerals, diopside, pectolite, fluor-apophyllite, fluorite, and garnet. A series of coupled heat and mass transport calculations was undertaken to provide thermal constraints for the aureole, in the absence of robust geothermometric assemblages, and insights into accompanying mass transport associated with the sedimentary rock-dike system. Calculations were completed for systems with homogeneous, anisotropic, and layered permeability, κ. Transport, dissolution, and precipitation of silica were also incorporated into calculations. All systems modeled indicate that the thermal pulse waned in ∼3 yr with a return to background temperatures in ∼10 yr. Heat and fluid transport produce maximum temperature isotherms that are distinctly different in spatial extent and lateral variability for each numerical system. The homogeneous κ case produced isotherms that pinch and swell vertically above the dike and have large lateral variations, in contrast to the anisotropic κ case that produced a single large plume above the dike. The layered system κ case produced the most spatially extensive thermal aureole, unlike that recorded in the rocks. Addition of dissolved silica to the flow system significantly impacts the calculated transport of heat and fluid, primarily due to density changes that affect upwelling dynamics. Although precipitation and dissolution of SiO2 can affect flow through the feedback to permeability, κ changes were found to be minor for these system conditions. Where κ decreased, flow was refocused into higher κ zones, thus mitigating the κ differences over time. This negative feedback tends to defocus flow and provides a mechanism for lateral migration of plumes. Coupled heat and silica transport produces a complex isotherm geometry surrounding the intrusion due to formation of upwelling and downwelling plumes and lateral translation of plumes, leading to variability in the isotherm pattern that does not reflect the inherent heterogeneity of the initial material properties. Initial heterogeneities in κ are not a prerequisite for the development of a complicated flow and transport pattern. In addition, if isotherms reflect isograds, these calculations demonstrate that isograds may not form uniform structures with isograd boundaries characterized by their distance from the heat source.

Studying hemispheric lateralization during a Stroop task through near-infrared spectroscopy-based connectivity

NASA Astrophysics Data System (ADS)

Zhang, Lei; Sun, Jinyan; Sun, Bailei; Luo, Qingming; Gong, Hui

2014-05-01

Near-infrared spectroscopy (NIRS) is a developing and promising functional brain imaging technology. Developing data analysis methods to effectively extract meaningful information from collected data is the major bottleneck in popularizing this technology. In this study, we measured hemodynamic activity of the prefrontal cortex (PFC) during a color-word matching Stroop task using NIRS. Hemispheric lateralization was examined by employing traditional activation and novel NIRS-based connectivity analyses simultaneously. Wavelet transform coherence was used to assess intrahemispheric functional connectivity. Spearman correlation analysis was used to examine the relationship between behavioral performance and activation/functional connectivity, respectively. In agreement with activation analysis, functional connectivity analysis revealed leftward lateralization for the Stroop effect and correlation with behavioral performance. However, functional connectivity was more sensitive than activation for identifying hemispheric lateralization. Granger causality was used to evaluate the effective connectivity between hemispheres. The results showed increased information flow from the left to the right hemispheres for the incongruent versus the neutral task, indicating a leading role of the left PFC. This study demonstrates that the NIRS-based connectivity can reveal the functional architecture of the brain more comprehensively than traditional activation, helping to better utilize the advantages of NIRS.

Performance improvement of the one-dot lateral flow immunoassay for aflatoxin B1 by using a smartphone-based reading system.

PubMed

Lee, Sangdae; Kim, Giyoung; Moon, Jihea

2013-04-18

This study was conducted to develop a simple, rapid, and accurate lateral flow immunoassay (LFIA) detection method for point-of-care diagnosis. The one-dot LFIA for aflatoxin B1 (AFB1) was based on the modified competitive binding format using competition between AFB1 and colloidal gold-AFB1-BSA conjugate for antibody binding sites in the test zone. A Smartphone-based reading system consisting of a Samsung Galaxy S2 Smartphone, a LFIA reader, and a Smartphone application for the image acquisition and data analysis. The detection limit of one-dot LFIA for AFB1 is 5 μg/kg. This method provided semi-quantitative analysis of AFB1 samples in the range of 5 to 1,000 μg/kg. Using combination of the one-dot LFIA and the Smartphone-based reading system, it is possible to conduct a more fast and accurate point-of-care diagnosis.

Performance Improvement of the One-Dot Lateral Flow Immunoassay for Aflatoxin B1 by Using a Smartphone-Based Reading System

PubMed Central

Lee, Sangdae; Kim, Giyoung; Moon, Jihea

2013-01-01

This study was conducted to develop a simple, rapid, and accurate lateral flow immunoassay (LFIA) detection method for point-of-care diagnosis. The one-dot LFIA for aflatoxin B1 (AFB1) was based on the modified competitive binding format using competition between AFB1 and colloidal gold-AFB1-BSA conjugate for antibody binding sites in the test zone. A Smartphone-based reading system consisting of a Samsung Galaxy S2 Smartphone, a LFIA reader, and a Smartphone application for the image acquisition and data analysis. The detection limit of one-dot LFIA for AFB1 is 5 μg/kg. This method provided semi-quantitative analysis of AFB1 samples in the range of 5 to 1,000 μg/kg. Using combination of the one-dot LFIA and the Smartphone-based reading system, it is possible to conduct a more fast and accurate point-of-care diagnosis. PMID:23598499

Rapid authentication of Cordyceps by lateral flow dipstick.

PubMed

Wong, Yuk-Lau; Wong, Ka-Lok; Shaw, Pang-Chui

2015-01-01

Cordyceps (Dongchongxiacao), a valuable traditional Chinese medicine, is composed of the fruiting body of Ophiocordyceps sinensis (Family: Ophiocordycipitaceae) on a caterpillar of ghost-moth species (Family: Hepialidae). Owing to its multiple potential functions, Cordyceps are in great demand and represent significant economic value. Adulterants or substitutes named Cordyceps or Chongcao from related fungi have been reported. In this study, polymerase chain reaction (PCR) coupled with a lateral flow dipstick (LFD) system was developed to distinguish genuine herb O. sinensis from its common adulterant Cordyceps gunnii and Cordyceps militaris. Specific primers (EF-CS-F1-Biotin, EF-CG-F1-Biotin and EF-CM-F1- Biotin) were designed to differentiate the three Cordyceps species. Internal control (EF-F1-b-DIG and EF-R1-FITC) was included to minimize the false signal due to PCR inhibitors or DNA degradation. LFD was then successfully employed for speedy and accurate detection of the respective PCR products. Copyright © 2015 Elsevier B.V. All rights reserved.

Rapid screening test for detection of oxytetracycline residues in milk using lateral flow assay.

PubMed

Naik, Laxmana; Sharma, Rajan; Mann, Bimlesh; Lata, Kiran; Rajput, Y S; Surendra Nath, B

2017-03-15

A rapid, semi-quantitative lateral flow assay (LFA) was developed to screen the oxytetracycline (OTC) antibiotics residues in milk samples. In this study a competitive immuno-assay format was established. Colloidal gold nano-particles (GNP) were prepared and used as labelling material in LFA. Polyclonal antibodies were generated against OTC molecule (anti-OTC), purified and the quality was assessed by enzyme linked immuno sorbet assay. For the first time membrane components required for LFA in milk system was optimized. GNP and anti-OTC stable conjugate preparation method was standardized, and then these components were placed over the conjugate pad. OTC coupled with carrier protein was placed on test line; species specific secondary antibodies were placed on the control line of the membrane matrix. Assay was validated by spiking OTC to antibiotic free milk samples and results could be accomplished within 5min. without need of any equipment. The visual detection limit was 30ppb. Copyright © 2016 Elsevier Ltd. All rights reserved.

Study of the flow mixing in a novel ARID raceway for algae production

DOE PAGES

Xu, Ben; Li, Peiwen; Waller, P.

2014-07-31

A novel flow field for algae raceways has been proposed, which is fundamentally different from traditional paddlewheel-driven raceways. To reduce freezing and heat loss in the raceway during cold time, the water is drained to a deep storage canal. The ground bed of the new raceway has a low slope so that water, lifted by propeller pump, can flow down in laterally-laid serpentine channels, relying on gravitational force. The flow rate of water is controlled so that it can overflow the lateral channel walls and mix with the main flow in the next lower channel, which thus creates a bettermore » mixing. In order to optimize the design parameters of the new flow field, methods including flow visualization, local point velocity measurement, and CFD analysis were employed to investigate the flow mixing features. Different combinations of channel geometries and water velocities were evaluated. An optimized flow field design and details of flow mixing are presented. The study offers an innovative design for large scale algae growth raceways which is of significance to the algae and biofuel industry.« less

Study of the flow mixing in a novel ARID raceway for algae production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Ben; Li, Peiwen; Waller, P.

A novel flow field for algae raceways has been proposed, which is fundamentally different from traditional paddlewheel-driven raceways. To reduce freezing and heat loss in the raceway during cold time, the water is drained to a deep storage canal. The ground bed of the new raceway has a low slope so that water, lifted by propeller pump, can flow down in laterally-laid serpentine channels, relying on gravitational force. The flow rate of water is controlled so that it can overflow the lateral channel walls and mix with the main flow in the next lower channel, which thus creates a bettermore » mixing. In order to optimize the design parameters of the new flow field, methods including flow visualization, local point velocity measurement, and CFD analysis were employed to investigate the flow mixing features. Different combinations of channel geometries and water velocities were evaluated. An optimized flow field design and details of flow mixing are presented. The study offers an innovative design for large scale algae growth raceways which is of significance to the algae and biofuel industry.« less

Quantifying flow-dependent changes in subyearling fall chinook salmon rearing habitat using two-dimensional spatially explicit modeling

USGS Publications Warehouse

Tiffan, K.F.; Garland, R.D.; Rondorf, D.W.

2002-01-01

We used an analysis based on a geographic information system (GIS) to determine the amount of rearing habitat and stranding area for subyearling fall chinook salmon Oncorhynchus tshawytscha in the Hanford Reach of the Columbia River at steady-state flows ranging from 1,416 to 11,328 m3/s. High-resolution river channel bathymetry was used in conjunction with a two-dimensional hydrodynamic model to estimate water velocities, depths, and lateral slopes throughout our 33-km study area. To relate the probability of fish presence in nearshore habitats to measures of physical habitat, we developed a logistic regression model from point electrofishing data. We only considered variables that were compatible with a GIS and therefore excluded other variables known to be important to juvenile salmonids. Water velocity and lateral slope were the only two variables included in our final model. The amount of available rearing habitat generally decreased as flow increased, with the greatest decreases occurring between 1,416 and 4,814 m3/s. When river discharges were between 3,682 and 7,080 m3/s, flow fluctuations of 566 m3/s produced the smallest change in available rearing area (from -6.3% to +6.8% of the total). Stranding pool area was greatly reduced at steady-state flows exceeding 4,531 m3/s, but the highest net gain in stranding area was produced by 850 m3/s decreases in flow when river discharges were between 5,381 and 5,664 m3/s. Current measures to protect rearing fall chinook salmon include limiting flow fluctuations at Priest Rapids Dam to 850 m3/s when the dam is spilling water and when the weekly flows average less than 4,814 m3/s. We believe that limiting flow fluctuations at all discharges would further protect subyearling fall chinook salmon.

Experimental testing of flexible barriers for containment of debris flows

USGS Publications Warehouse

DeNatale, Jay S.; Iverson, Richard M.; Major, Jon J.; LaHusen, Richard G.; Fliegel, Gregg L.; Duffy, John D.

1999-01-01

In June 1996, six experiments conducted at the U.S. Geological Survey Debris Flow Flume demonstrated that flexible, vertical barriers constructed of wire rope netting can stop small debris flows. All experimental debris flows consisted of water-saturated gravelly sand with less than two percent finer sediment by weight. All debris flows had volumes of about 10 cubic meters, masses of about 20 metre tons, and impact velocities of 5 to 9 meters per second. In four experiments, the debris flow impacted pristine, unreformed barriers of varying design; in the other two experiments, the debris flow impacted barriers already loaded with sediment from a previous flow. Differences in barrier design led to differences in barrier performance. Experiments were conducted with barriers constructed of square-mesh wire-rope netting with 30centimeter, 20centimeter, and 15 centimeter mesh openings as well as 30centimeter diameter interlocking steel rings. In all cases, sediment cascading downslope at the leading edge of the debris flows tended to spray through the nets. Nets fitted with finer-mesh chain link or chicken wire liners contained more sediment than did unlined nets, and a ring net fitted with a synthetic silt screen liner contained nearly 100 percent of the sediment. Irreversible net displacements of up to 2 meters and friction brake engagement on the support and anchor cables dissipated some of the impact energy. However, substantial forces developed in the steel support columns and the lateral and tie-back anchor cables attached to these columns. As predicted by elementary mechanics, the anchor cables experienced larger tensile forces when the support columns were hinged at the base rather than bolted rigidly to the foundation. Measured loads in the lateral anchor cables exceeded those in the tie-back anchor cables and the load cell capacity of 45 kilo-Newtons. Measurements also indicated that the peak loads in the tie- back anchors were highly transient and occurred at the points of maximum momentum impulse to the net.

Fluorescent carbon nanoparticle-based lateral flow biosensor for ultrasensitive detection of DNA.

PubMed

Takalkar, Sunitha; Baryeh, Kwaku; Liu, Guodong

2017-12-15

We report a fluorescent carbon nanoparticle (FCN)-based lateral flow biosensor for ultrasensitive detection of DNA. Fluorescent carbon nanoparticle with a diameter of around 15nm was used as a tag to label a detection DNA probe, which was complementary with the part of target DNA. A capture DNA probe was immobilized on the test zone of the lateral flow biosensor. Sandwich-type hybridization reactions among the FCN-labeled DNA probe, target DNA and capture DNA probe were performed on the lateral flow biosensor. In the presence of target DNA, FCNs were captured on the test zone of the biosensor and the fluorescent intensity of the captured FCNs was measured with a portable fluorescent reader. After systematic optimizations of experimental parameters (the components of running buffers, the concentration of detection DNA probe used in the preparation of FCN-DNA conjugates, the amount of FCN-DNA dispensed on the conjugate pad and the dispensing cycles of the capture DNA probes on the test-zone), the biosensor could detect a minimum concentration of 0.4 fM DNA. This study provides a rapid and low-cost approach for DNA detection with high sensitivity, showing great promise for clinical application and biomedical diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.

Young and Old Flows

NASA Technical Reports Server (NTRS)

2004-01-01

[figure removed for brevity, see original site]

Released 9 April 2004 The Odyssey spacecraft has completed a full Mars year of observations of the red planet. For the next several weeks the Image of the Day will look back over this first mars year. It will focus on four themes: 1) the poles -- with the seasonal changes seen in the retreat and expansion of the caps; 2) craters - with a variety of morphologies relating to impact materials and later alteration, both infilling and exhumation; 3) channels -- the clues to liquid surface flow; and 4) volcanic flow features. While some images have helped answer questions about the history of Mars, many have raised new questions that are still being investigated as Odyssey continues collecting data as it orbits Mars.

This daytime infrared image was collected Aug. 13, 2003 during southern spring. The upper part of the image shows the relatively young volcanic flows from Arsia Mons, while the bottom exhibits the flow front texture of older flows. The older flows are most likely also from Arsia Mons.

Image information: IR instrument. Latitude -27.8, Longitude 237.5 East (122.5 West). 19 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

The perfect debris flow? Aggregated results from 28 large-scale experiments

USGS Publications Warehouse

Iverson, Richard M.; Logan, Matthew; LaHusen, Richard G.; Berti, Matteo

2010-01-01

Aggregation of data collected in 28 controlled experiments reveals reproducible debris-flow behavior that provides a clear target for model tests. In each experiment ∼10 m3 of unsorted, water-saturated sediment composed mostly of sand and gravel discharged from behind a gate, descended a steep, 95-m flume, and formed a deposit on a nearly horizontal runout surface. Experiment subsets were distinguished by differing basal boundary conditions (1 versus 16 mm roughness heights) and sediment mud contents (1 versus 7 percent dry weight). Sensor measurements of evolving flow thicknesses, basal normal stresses, and basal pore fluid pressures demonstrate that debris flows in all subsets developed dilated, coarse-grained, high-friction snouts, followed by bodies of nearly liquefied, finer-grained debris. Mud enhanced flow mobility by maintaining high pore pressures in flow bodies, and bed roughness reduced flow speeds but not distances of flow runout. Roughness had these effects because it promoted debris agitation and grain-size segregation, and thereby aided growth of lateral levees that channelized flow. Grain-size segregation also contributed to development of ubiquitous roll waves, which had diverse amplitudes exhibiting fractal number-size distributions. Despite the influence of these waves and other sources of dispersion, the aggregated data have well-defined patterns that help constrain individual terms in a depth-averaged debris-flow model. The patterns imply that local flow resistance evolved together with global flow dynamics, contradicting the hypothesis that any consistent rheology applied. We infer that new evolution equations, not new rheologies, are needed to explain how characteristic debris-flow behavior emerges from the interactions of debris constituents.

Flow characteristics and spillage mechanisms of wall-mounted and jet-isolated range hoods subject to influence from cross draft.

PubMed

Chen, Jia-Kun; Huang, Rong Fung; Peng, Kuan-Lin

2012-01-01

The effects of draft on the flow and spillage characteristics of wall-mounted and jet-isolated range hoods were investigated. A specially designed draft generator that could supply low-swirl air current was used to provide "cross draft" from three directions, lateral (θ = 0(o)), oblique (θ = 45(o)), and front (θ = 90(o)), with respect to the center point of the range hoods. Flow characteristics of oil mist were inspected through visualization of smoke flows with light scattering (laser light sheet-assisted visualization of smoke flow). The leakage mechanisms, which were closely related to the flow features, were studied by examining both movies and still pictures showing smoke-flow evolution. The sulfur hexafluoride tracer gas concentration detection method was employed to measure the capture indices. The results showed that the lateral draft pushed the pollutants generated under the hood in the opposite direction and induced serious spillage. The oblique draft pushed the pollutants toward both the rear wall and opposite side and induced more serious spillage than did the lateral draft. The frontal draft forced the pollutants to bifurcate into streams moving toward the left and the right, and induced the most serious pollutant spillage among the three tested drafts. Pollutant spillage became critically significant as the cross draft velocity was increased to greater than 0.2 m/sec. Spillage of pollutants increased as the velocity of the cross draft was increased. Increasing the suction flow rate of the range hood may increase resistance to the draft, but the benefits were limited at draft velocities greater than 0.2 m/sec. Both range hoods had a similarly low capture index under the influence of the lateral draft. For the oblique and frontal drafts, the jet-isolated range hood demonstrated a higher capture index than did the wall-mounted range hood.

What determines blood vessel structure? Genetic prespecification vs. hemodynamics.

PubMed

Jones, Elizabeth A V; le Noble, Ferdinand; Eichmann, Anne

2006-12-01

Vascular network remodeling, angiogenesis, and arteriogenesis play an important role in the pathophysiology of ischemic cardiovascular diseases and cancer. Based on recent studies of vascular network development in the embryo, several novel aspects to angiogenesis have been identified as crucial to generate a functional vascular network. These aspects include specification of arterial and venous identity in vessels and network patterning. In early embryogenesis, vessel identity and positioning are genetically hardwired and involve neural guidance genes expressed in the vascular system. We demonstrated that, during later stages of embryogenesis, blood flow plays a crucial role in regulating vessel identity and network remodeling. The flow-evoked remodeling process is dynamic and involves a high degree of vessel plasticity. The open question in the field is how genetically predetermined processes in vessel identity and patterning balance with the contribution of blood flow in shaping a functional vascular architecture. Although blood flow is essential, it remains unclear to what extent flow is able to act on the developing cardiovascular system. There is significant evidence that mechanical forces created by flowing blood are biologically active within the embryo and that the level of mechanical forces and the type of flow patterns present in the embryo are able to affect gene expression. Here, we highlight the pivotal role for blood flow and physical forces in shaping the cardiovascular system.

The effects of different lying positions on interface pressure, skin temperature, and tissue blood flow in nursing home residents.

PubMed

Källman, Ulrika; Engström, Maria; Bergstrand, Sara; Ek, Anna-Christina; Fredrikson, Mats; Lindberg, Lars-Göran; Lindgren, Margareta

2015-03-01

Although repositioning is considered an important intervention to prevent pressure ulcers, tissue response during loading in different lying positions has not been adequately explored. To compare the effects of different lying positions on interface pressure, skin temperature, and tissue blood flow in nursing home residents. From May 2011 to August 2012, interface pressure, skin temperature, and blood flow at three tissue depths were measured for 1 hr over the sacrum in 30° supine tilt and 0° supine positions and over the trochanter major in 30° lateral and 90° lateral positions in 25 residents aged 65 years or older. Measurement of interface pressure was accomplished using a pneumatic pressure transmitter connected to a digital manometer, skin temperature using a temperature sensor, and blood flow using photoplethysmography and laser Doppler flowmetry. Interface pressure was significantly higher in the 0° supine and 90° lateral positions than in 30° supine tilt and 30° lateral positions. The mean skin temperature increased from baseline in all positions. Blood flow was significantly higher in the 30° supine tilt position compared to the other positions. A hyperemic response in the post pressure period was seen at almost all tissue depths and positions. The 30° supine tilt position generated less interface pressure and allowed greater tissue perfusion, suggesting that this position is the most beneficial. © The Author(s) 2014.

A sprinkling experiment to quantify celerity-velocity differences at the hillslope scale.

PubMed

van Verseveld, Willem J; Barnard, Holly R; Graham, Chris B; McDonnell, Jeffrey J; Brooks, J Renée; Weiler, Markus

2017-01-01

Few studies have quantified the differences between celerity and velocity of hillslope water flow and explained the processes that control these differences. Here, we asses these differences by combining a 24-day hillslope sprinkling experiment with a spatially explicit hydrologic model analysis. We focused our work on Watershed 10 at the H. J. Andrews Experimental Forest in western Oregon. Celerities estimated from wetting front arrival times were generally much faster than average vertical velocities of δ 2 H. In the model analysis, this was consistent with an identifiable effective porosity (fraction of total porosity available for mass transfer) parameter, indicating that subsurface mixing was controlled by an immobile soil fraction, resulting in the attenuation of the δ 2 H input signal in lateral subsurface flow. In addition to the immobile soil fraction, exfiltrating deep groundwater that mixed with lateral subsurface flow captured at the experimental hillslope trench caused further reduction in the δ 2 H input signal. Finally, our results suggest that soil depth variability played a significant role in the celerity-velocity responses. Deeper upslope soils damped the δ 2 H input signal, while a shallow soil near the trench controlled the δ 2 H peak in lateral subsurface flow response. Simulated exit time and residence time distributions with our hillslope hydrologic model showed that water captured at the trench did not represent the entire modeled hillslope domain; the exit time distribution for lateral subsurface flow captured at the trench showed more early time weighting.

A sprinkling experiment to quantify celerity-velocity differences at the hillslope scale

NASA Astrophysics Data System (ADS)

van Verseveld, Willem J.; Barnard, Holly R.; Graham, Chris B.; McDonnell, Jeffrey J.; Renée Brooks, J.; Weiler, Markus

2017-11-01

Few studies have quantified the differences between celerity and velocity of hillslope water flow and explained the processes that control these differences. Here, we asses these differences by combining a 24-day hillslope sprinkling experiment with a spatially explicit hydrologic model analysis. We focused our work on Watershed 10 at the H. J. Andrews Experimental Forest in western Oregon. Celerities estimated from wetting front arrival times were generally much faster than average vertical velocities of δ2H. In the model analysis, this was consistent with an identifiable effective porosity (fraction of total porosity available for mass transfer) parameter, indicating that subsurface mixing was controlled by an immobile soil fraction, resulting in the attenuation of the δ2H input signal in lateral subsurface flow. In addition to the immobile soil fraction, exfiltrating deep groundwater that mixed with lateral subsurface flow captured at the experimental hillslope trench caused further reduction in the δ2H input signal. Finally, our results suggest that soil depth variability played a significant role in the celerity-velocity responses. Deeper upslope soils damped the δ2H input signal, while a shallow soil near the trench controlled the δ2H peak in lateral subsurface flow response. Simulated exit time and residence time distributions with our hillslope hydrologic model showed that water captured at the trench did not represent the entire modeled hillslope domain; the exit time distribution for lateral subsurface flow captured at the trench showed more early time weighting.

Natural and anthropogenic land cover change and its impact on the regional climate and hydrological extremes over Sanjiangyuan region

NASA Astrophysics Data System (ADS)

Ji, P.; Yuan, X.

2017-12-01

Located in the northern Tibetan Plateau, Sanjiangyuan is the headwater region of the Yellow River, Yangtze River and Mekong River. Besides climate change, natural and human-induced land cover change (e.g., Graze for Grass Project) is also influencing the regional hydro-climate and hydrological extremes significantly. To quantify their impacts, a land surface model (LSM) with consideration of soil moisture-lateral surface flow interaction and quasi-three-dimensional subsurface flow, is used to conduct long-term high resolution simulations driven by China Meteorological Administration Land Data Assimilation System forcing data and different land cover scenarios. In particular, the role of surface and subsurface lateral flows is also analyzed by comparing with typical one-dimensional models. Lateral flows help to simulate soil moisture variability caused by topography at hyper-resolution (e.g., 100m), which is also essential for simulating hydrological extremes including soil moisture dryness/wetness and high/low flows. The LSM will also be coupled with a regional climate model to simulate the effect of natural and anthropogenic land cover change on regional climate, with particular focus on the land-atmosphere coupling at different resolutions with different configurations in modeling land surface hydrology.

Evaluating post-wildfire hydrologic recovery using ParFlow in southern California

NASA Astrophysics Data System (ADS)

Lopez, S. R.; Kinoshita, A. M.; Atchley, A. L.

2016-12-01

Wildfires are naturally occurring hazards that can have catastrophic impacts. They can alter the natural processes within a watershed, such as surface runoff and subsurface water storage. Generally, post-fire hydrologic models are either one-dimensional, empirically-based models, or two-dimensional, conceptually-based models with lumped parameter distributions. These models are useful in providing runoff measurements at the watershed outlet; however, do not provide distributed hydrologic simulation at each point within the watershed. This research demonstrates how ParFlow, a three-dimensional, distributed hydrologic model can simulate post-fire hydrologic processes by representing soil burn severity (via hydrophobicity) and vegetation recovery as they vary both spatially and temporally. Using this approach, we are able to evaluate the change in post-fire water components (surface flow, lateral flow, baseflow, and evapotranspiration). This model is initially developed for a hillslope in Devil Canyon, burned in 2003 by the Old Fire in southern California (USA). The domain uses a 2m-cell size resolution over a 25 m by 25 m lateral extent. The subsurface reaches 2 m and is assigned a variable cell thickness, allowing an explicit consideration of the soil burn severity throughout the stages of recovery and vegetation regrowth. Vegetation regrowth is incorporated represented by satellite-based Enhanced Vegetation Index (EVI) products. The pre- and post-fire surface runoff, subsurface storage, and surface storage interactions are evaluated and will be used as a basis for developing a watershed-scale model. Long-term continuous simulations will advance our understanding of post-fire hydrological partitioning between water balance components and the spatial variability of watershed processes, providing improved guidance for post-fire watershed management.

Quasi 3D modeling of water flow in vadose zone and groundwater

USDA-ARS?s Scientific Manuscript database

The complexity of subsurface flow systems calls for a variety of concepts leading to the multiplicity of simplified flow models. One habitual simplification is based on the assumption that lateral flow and transport in unsaturated zone are not significant unless the capillary fringe is involved. In ...

Fuselage ventilation due to wind flow about a postcrash aircraft

NASA Technical Reports Server (NTRS)

Stuart, J. W.

1980-01-01

Postcrash aircraft fuselage fire development, dependent on the internal and external fluid dynamics is discussed. The natural ventilation rate, a major factor in the internal flow patterns and fire development is reviewed. The flow about the fuselage as affected by the wind and external fire is studied. An analysis was performend which estimated the rates of ventilation produced by the wind for a limited idealized environmental configuration. The simulation utilizes the empirical pressure coefficient distribution of an infinite circular cylinder near a wall with its boundary later flow to represent the atmospheric boundary layer. The resulting maximum ventilation rate for two door size openings, with varying circumferential location in a common 10 mph wind was an order of magnitude greater than the forced ventilation specified in full scale fire testing. The parameter discussed are: (1) fuselage size and shape, (2) fuselage orientation and proximity to the ground, (3) fuselage-openings size and location, (4) wind speed and direction, and (5) induced flow of the external fire plume is recommended. The fire testing should be conducted to a maximum ventilation rate at least an order of magnitude greater than the inflight air conditioning rates.

Effect of dehydration on the development of collaterals in acute middle cerebral artery occlusion.

PubMed

Chang, S-W; Huang, Y-C; Lin, L-C; Yang, J-T; Weng, H-H; Tsai, Y-H; Lee, T-H

2016-03-01

Recent large series studies have demonstrated that dehydration is common amongst stroke subjects and is associated with poor outcome. However, the effects of hydration status on the development of collaterals have never been discussed. In this study, the hypothesis that hydration status is an important factor for developing collaterals after acute middle cerebral artery (MCA) infarction was tested. Eighty-seven patients with acute infarction due to occlusion of the MCA were enrolled. Two collateral markers, posterior cerebral artery (PCA) laterality and fluid-attenuated inversion recovery hyperintense vessels (HVs) were assessed from magnetic resonance imaging. Dehydration status was defined by a nitrogen to creatinine ratio ≧ of 15. The associations between dehydration status and the development of collaterals were estimated. Sixty-one of 87 patients (70.1%) were identified as dehydrated. The development of PCA laterality and HVs shows a significant difference between dehydrated and euhydrated patients. A serum nitrogen to creatinine ratio <15, diastolic blood pressure and the presence of a dense MCA on computed tomography were significantly associated with the development of PCA laterality. A serum nitrogen to creatinine ratio <15, the initial National Institutes of Health Stroke Scale score, the presence of a dense MCA and calcifications of the internal carotid artery on computed tomography were significantly associated with the development of HVs. Dehydration remained an independent negative predictor for the development of PCA laterality and HVs in the multivariate analysis. Hydration status is associated with the development of collateral flow after acute MCA occlusion. This preliminary study provides an imaging clue that hydration status and early hydration therapy could be important for acute stroke management. © 2016 EAN.

Point-of-care coagulation monitoring: first clinical experience using a paper-based lateral flow diagnostic device.

PubMed

Hegener, Michael A; Li, Hua; Han, Daewoo; Steckl, Andrew J; Pauletti, Giovanni M

2017-09-01

Vitamin K antagonists such as warfarin are the most widely used class of oral anticoagulants. Due to a narrow therapeutic window, patients on warfarin require regular monitoring. Self-testing using point-of-care (POC) diagnostic devices is available, but cost makes this monitoring method beyond reach for many. The main objective of this research was to assess the clinical utility of a low-cost, paper-based lateral flow POC diagnostic device developed for anticoagulation monitoring without the need for a separate electronic reader. Custom-fabricated lateral flow assay (LFA) test strips comprised of a glass fiber sample pad, a nitrocellulose analytical membrane, a cellulose wicking pad, and a plastic backing card were assembled in a plastic cassette. Healthy volunteers and patients on warfarin therapy were recruited for this prospective study. For each participant, a whole blood sample was collected via fingerstick to determine: (1) international normalized ratio (INR) using the CoaguChek® XS coagulometer, (2) hematocrit by centrifugation, and (3) red blood cell (RBC) travel distance on the experimental LFA device after 240 s using digital image analysis. RBC travel distance measured on the LFA device using blood samples obtained from warfarin patients positively correlated with increasing INR value and the LFA device had the capability to statistically distinguish between healthy volunteer INR values and those for patients groups with INR ≥ 2.6. From these data, it is predicted that this low-cost, paper-based LFA device can have clinical utility for identifying anticoagulated patients taking vitamin K antagonists who are outside of the desired therapeutic efficacy window.

Spatially explicit simulation of peatland hydrology and carbon dioxide exchange: Influence of mesoscale topography

NASA Astrophysics Data System (ADS)

Sonnentag, O.; Chen, J. M.; Roulet, N. T.; Ju, W.; Govind, A.

2008-06-01

Carbon dynamics in peatlands are controlled, in large part, by their wetness as defined by water table depth and volumetric liquid soil moisture content. A common type of peatland is raised bogs that typically have a multiple-layer canopy of vascular plants over a Sphagnum moss ground cover. Their convex form restricts water supply to precipitation and water is shed toward the margins, usually by lateral subsurface flow. The hydraulic gradient for lateral subsurface flow is governed by the peat surface topography at the mesoscale (˜200 m to 5 km). To investigate the influence of mesoscale topography on wetness, evapotranspiration (ET), and gross primary productivity (GPP) in a bog during the snow-free period, we compare the outputs of a further developed version of the daily Boreal Ecosystem Productivity Simulator (BEPS) with observations made at the Mer Bleue peatland, located near Ottawa, Canada. Explicitly considering mesoscale topography, simulated total ET and GPP correlate well with measured ET (r = 0.91) and derived gross ecosystem productivity (GEP; r = 0.92). Both measured ET and derived GEP are simulated similarly well when mesoscale topography is neglected, but daily simulated values are systematically underestimated by about 10% and 12% on average, respectively, due to greater wetness resulting from the lack of lateral subsurface flow. Owing to the differences in moss surface conductances of water vapor and carbon dioxide with increasing moss water content, the differences in the spatial patterns of simulated total ET and GPP are controlled by the mesotopographic position of the moss ground cover.

Near-infrared fluorescence-based multiplex lateral flow immunoassay for the simultaneous detection of four antibiotic residue families in milk.

PubMed

Chen, Yiqiang; Chen, Qian; Han, Miaomiao; Liu, Jiangyang; Zhao, Peng; He, Lidong; Zhang, Yuan; Niu, Yiming; Yang, Wenjun; Zhang, Liying

2016-05-15

In this study, we developed a novel near-infrared fluorescence based multiplex lateral flow immunoassay by conjugating a near-infrared label to broad-specificity monoclonal antibody/receptor as detection complexes. Different antigens were dispensed onto separate test zones of nitrocellulose membrane to serve as capture reagents. This assay format allowed the simultaneous detection of four families of antibiotics (β-lactams, tetracyclines, quinolones and sulfonamides) in milk within 20 min. Qualitative and quantitative analysis of target antibiotics were realized by imaging the fluorescence intensity of the near-infrared label captured on respective test lines. For qualitative analysis, the cut-off values of β-lactams, tetracyclines, quinolones and sulfonamides were determined to be 8 ng/mL, 2 ng/mL, 4 ng/mL and 8 ng/mL respectively, which were much lower than the conventional gold nanoparticle based lateral flow immunoassay. For quantitative analysis, the detection ranges were 0.26-3.56 ng/mL for β-lactams, 0.04-0.98 ng/mL for tetracyclines, 0.08-2.0 ng/mL for quinolones, and 0.1-3.98 ng/mL for sulfonamides, with linear correlation coefficients higher than 0.97. The mean spiked recoveries ranged from 93.7% to 108.2% with coefficient of variations less than 16.3%. These results demonstrated that this novel immunoassay is a promising approach for rapidly screening the four families of antibiotic residues in milk. Copyright © 2015 Elsevier B.V. All rights reserved.

Inhibition of recombinase polymerase amplification by background DNA: a lateral flow-based method for enriching target DNA.

PubMed

Rohrman, Brittany; Richards-Kortum, Rebecca

2015-02-03

Recombinase polymerase amplification (RPA) may be used to detect a variety of pathogens, often after minimal sample preparation. However, previous work has shown that whole blood inhibits RPA. In this paper, we show that the concentrations of background DNA found in whole blood prevent the amplification of target DNA by RPA. First, using an HIV-1 RPA assay with known concentrations of nonspecific background DNA, we show that RPA tolerates more background DNA when higher HIV-1 target concentrations are present. Then, using three additional assays, we demonstrate that the maximum amount of background DNA that may be tolerated in RPA reactions depends on the DNA sequences used in the assay. We also show that changing the RPA reaction conditions, such as incubation time and primer concentration, has little effect on the ability of RPA to function when high concentrations of background DNA are present. Finally, we develop and characterize a lateral flow-based method for enriching the target DNA concentration relative to the background DNA concentration. This sample processing method enables RPA of 10(4) copies of HIV-1 DNA in a background of 0-14 μg of background DNA. Without lateral flow sample enrichment, the maximum amount of background DNA tolerated is 2 μg when 10(6) copies of HIV-1 DNA are present. This method requires no heating or other external equipment, may be integrated with upstream DNA extraction and purification processes, is compatible with the components of lysed blood, and has the potential to detect HIV-1 DNA in infant whole blood with high proviral loads.

The diagnostic plot analysis of artesian aquifers with case studies in Table Mountain Group of South Africa

NASA Astrophysics Data System (ADS)

Sun, Xiaobin; Xu, Yongxin; Lin, Lixiang

2015-05-01

Parameter estimates of artesian aquifers where piezometric head is above ground level are largely made through free-flowing and recovery tests. The straight-line method proposed by Jacob-Lohman is often used for interpretation of flow rate measured at flowing artesian boreholes. However, the approach fails to interpret the free-flowing test data from two artesian boreholes in the fractured-rock aquifer in Table Mountain Group (TMG) of South Africa. The diagnostic plot method using the reciprocal rate derivative is adapted to evaluate the artesian aquifer properties. The variation of the derivative helps not only identify flow regimes and discern the boundary conditions, but also facilitates conceptualization of the aquifer system and selection of an appropriate model for data interpretation later on. Test data from two free-flowing tests conducted in different sites in TMG are analysed using the diagnostic plot method. Based on the results, conceptual models and appropriate approaches are developed to evaluate the aquifer properties. The advantages and limitations of using the diagnostic plot method on free-flowing test data are discussed.

Convection-induced distortion of a solid-liquid interface

NASA Technical Reports Server (NTRS)

Schaefer, R. J.; Coriell, S. R.

1984-01-01

Measurements of convective flow fields and solid-liquid interface shapes during the solidification of a pure and a slightly alloyed transparent material reveal that the convective transport of solute can cause a macroscopic depression to develop in the solid-liquid interface. This effect occurs under conditions close to those which are predicted to produce morphological instability of a planar interface. A cellular or dendritic microstructure later develops within the interface depression. The convection is attributed to the effect of radial temperature gradients in the crystal growth apparatus.

An investigation on the effect of street morphology to ambient air quality using six real-world cases

NASA Astrophysics Data System (ADS)

Shen, Jialei; Gao, Zhi; Ding, Wowo; Yu, Ying

2017-09-01

Street canyons are vulnerable to air pollution mainly caused by vehicle emissions, which are therefore closely related to pedestrians' health. Previous studies have showed that air quality in street canyons is associated with street morphology, though the majority of them have focused on idealized street models. This paper attempts to investigate the relationship of street morphology to air quality for 6 irregular real-world cases selected from America, Europe, and China, i.e. Manhattan, Paris, Barcelona, Berlin, London and Nanjing. Each street is analyzed as a set of slices to propose a couple of morphology indices for quantitatively assessing the actual street morphology. Pollutant transport rate of mean flows and turbulent diffusion, net escape velocity and age of air are obtained from computational fluid dynamics (CFD) simulations to assess the ventilations and pollutant dispersion within street canyons with a parallel approaching wind. The results show that the street morphology characteristics, including the street width, lateral openings and intersections, are closely related to the air flows in street canyons. The air quality improves with a decreasing aspect ratio of central street owing to a larger vertical exchange through the street roof, which suggests an open central street is of better air quality. The lateral openings and intersections of streets have important effects on the air flows in street canyons, and the effects are particularly pronounced when the street widths are similar. The street continuity ratio indicates street continuity. It relates to the openings and the symmetry of a street and impacts on the air flows and pollutant dispersion through the lateral openings of the central street. The street spatial closure ratio is determined by the street continuity ratio and the aspect ratio of the central street. When the aspect ratio of central street is not excessively high, higher values of street continuity ratio and spatial closure ratio can lead to a stronger channel flow in street canyons and improve the air quality. The octagon intersections are favorable for air flowing through the lateral openings and improve the channel flows. The oblique intersections can also greatly improve the street ventilations, mainly due to the enhanced air flows through the lateral openings and the increased turbulent diffusion through the street roofs.

Predicting Peak Flows following Forest Fires

NASA Astrophysics Data System (ADS)

Elliot, William J.; Miller, Mary Ellen; Dobre, Mariana

2016-04-01

Following forest fires, peak flows in perennial and ephemeral streams often increase by a factor of 10 or more. This increase in peak flow rate may overwhelm existing downstream structures, such as road culverts, causing serious damage to road fills at stream crossings. In order to predict peak flow rates following wildfires, we have applied two different tools. One is based on the U.S.D.A Natural Resource Conservation Service Curve Number Method (CN), and the other is by applying the Water Erosion Prediction Project (WEPP) to the watershed. In our presentation, we will describe the science behind the two methods, and present the main variables for each model. We will then provide an example of a comparison of the two methods to a fire-prone watershed upstream of the City of Flagstaff, Arizona, USA, where a fire spread model was applied for current fuel loads, and for likely fuel loads following a fuel reduction treatment. When applying the curve number method, determining the time to peak flow can be problematic for low severity fires because the runoff flow paths are both surface and through shallow lateral flow. The WEPP watershed version incorporates shallow lateral flow into stream channels. However, the version of the WEPP model that was used for this study did not have channel routing capabilities, but rather relied on regression relationships to estimate peak flows from individual hillslope polygon peak runoff rates. We found that the two methods gave similar results if applied correctly, with the WEPP predictions somewhat greater than the CN predictions. Later releases of the WEPP model have incorporated alternative methods for routing peak flows that need to be evaluated.

Comparisons of a Three-Dimensional, Full Navier Stokes Computer Model with High Mach Number Combuster Test Data

NASA Technical Reports Server (NTRS)

Watkins, William B.

1990-01-01

Comparisons between scramjet combustor data and a three-dimensional full Navier-Stokes calculation have been made to verify and substantiate computational fluid dynamics (CFD) codes and application procedures. High Mach number scramjet combustor development will rely heavily on CFD applications to provide wind tunnel-equivalent data of quality sufficient to design, build and fly hypersonic aircraft. Therefore. detailed comparisons between CFD results and test data are imperative. An experimental case is presented, for which combustor wall static pressures were measured and flow-fieid interferograms were obtained. A computer model was done of the experiment, and counterpart parameters are compared with experiment. The experiment involved a subscale combustor designed and fabricated for the National Aero-Space Plane Program, and tested in the Calspan Corporation 96" hypersonic shock tunnel. The combustor inlet ramp was inclined at a 20 angle to the shock tunnel nozzle axis, and resulting combustor entrance flow conditions simulated freestream M=10. The combustor body and cowl walls were instrumented with static pressure transducers, and the combustor lateral walls contained windows through which flowfield holographic interferograms were obtained. The CFD calculation involved a three-dimensional time-averaged full Navier-Stokes code applied to the axial flow segment containing fuel injection and combustion. The full Navier-Stokes approach allowed for mixed supersonic and subsonic flow, downstream-upstream communication in subsonic flow regions, and effects of adverse pressure gradients. The code included hydrogen-air chemistry in the combustor segment which begins near fuel injection and continues through combustor exhaust. Combustor ramp and inlet segments on the combustor lateral centerline were modelled as two dimensional. Comparisons to be shown include calculated versus measured wall static pressures as functions of axial flow coordinate, and calculated path-averaged density contours versus an holographic Interferogram.

Gene flow and biological conflict systems in the origin and evolution of eukaryotes

PubMed Central

Aravind, L.; Anantharaman, Vivek; Zhang, Dapeng; de Souza, Robson F.; Iyer, Lakshminarayan M.

2012-01-01

The endosymbiotic origin of eukaryotes brought together two disparate genomes in the cell. Additionally, eukaryotic natural history has included other endosymbiotic events, phagotrophic consumption of organisms, and intimate interactions with viruses and endoparasites. These phenomena facilitated large-scale lateral gene transfer and biological conflicts. We synthesize information from nearly two decades of genomics to illustrate how the interplay between lateral gene transfer and biological conflicts has impacted the emergence of new adaptations in eukaryotes. Using apicomplexans as example, we illustrate how lateral transfer from animals has contributed to unique parasite-host interfaces comprised of adhesion- and O-linked glycosylation-related domains. Adaptations, emerging due to intense selection for diversity in the molecular participants in organismal and genomic conflicts, being dispersed by lateral transfer, were subsequently exapted for eukaryote-specific innovations. We illustrate this using examples relating to eukaryotic chromatin, RNAi and RNA-processing systems, signaling pathways, apoptosis and immunity. We highlight the major contributions from catalytic domains of bacterial toxin systems to the origin of signaling enzymes (e.g., ADP-ribosylation and small molecule messenger synthesis), mutagenic enzymes for immune receptor diversification and RNA-processing. Similarly, we discuss contributions of bacterial antibiotic/siderophore synthesis systems and intra-genomic and intra-cellular selfish elements (e.g., restriction-modification, mobile elements and lysogenic phages) in the emergence of chromatin remodeling/modifying enzymes and RNA-based regulation. We develop the concept that biological conflict systems served as evolutionary “nurseries” for innovations in the protein world, which were delivered to eukaryotes via lateral gene flow to spur key evolutionary innovations all the way from nucleogenesis to lineage-specific adaptations. PMID:22919680

The sensory basis of rheotaxis in turbulent flow

NASA Astrophysics Data System (ADS)

Elder, John P.

Rheotaxis is a robust, multisensory behavior with many potential benefits for fish and other aquatic animals, yet the influence of different fluvial conditions on rheotactic performance and its sensory basis is still poorly understood. Here, we examine the role that vision and the lateral line play in the rheotactic behavior of a stream-dwelling species (Mexican tetra, Astyanax mexicanus) under both rectilinear and turbulent flow conditions. Turbulence enhanced overall rheotactic strength and lowered the flow speed at which rheotaxis was initiated; this effect did not depend on the availability of either visual or lateral line information. Compared to fish without access to visual information, fish with access to visual information exhibited increased levels of positional stability and as a result, increased levels of rheotactic accuracy. No disruption in rheotactic performance was found when the lateral line was disabled, suggesting that this sensory system is not necessary for either rheotaxis or turbulence detection under the conditions of this study.

High-speed video capillaroscopy method for imaging and evaluation of moving red blood cells

NASA Astrophysics Data System (ADS)

Gurov, Igor; Volkov, Mikhail; Margaryants, Nikita; Pimenov, Aleksei; Potemkin, Andrey

2018-05-01

The video capillaroscopy system with high image recording rate to resolve moving red blood cells with velocity up to 5 mm/s into a capillary is considered. Proposed procedures of the recorded video sequence processing allow evaluating spatial capillary area, capillary diameter and central line with high accuracy and reliability independently on properties of individual capillary. Two-dimensional inter frame procedure is applied to find lateral shift of neighbor images in the blood flow area with moving red blood cells and to measure directly the blood flow velocity along a capillary central line. The developed method opens new opportunities for biomedical diagnostics, particularly, due to long-time continuous monitoring of red blood cells velocity into capillary. Spatio-temporal representation of capillary blood flow is considered. Experimental results of direct measurement of blood flow velocity into separate capillary as well as capillary net are presented and discussed.

Localization of source with unknown amplitude using IPMC sensor arrays

NASA Astrophysics Data System (ADS)

Abdulsadda, Ahmad T.; Zhang, Feitian; Tan, Xiaobo

2011-04-01

The lateral line system, consisting of arrays of neuromasts functioning as flow sensors, is an important sensory organ for fish that enables them to detect predators, locate preys, perform rheotaxis, and coordinate schooling. Creating artificial lateral line systems is of significant interest since it will provide a new sensing mechanism for control and coordination of underwater robots and vehicles. In this paper we propose recursive algorithms for localizing a vibrating sphere, also known as a dipole source, based on measurements from an array of flow sensors. A dipole source is frequently used in the study of biological lateral lines, as a surrogate for underwater motion sources such as a flapping fish fin. We first formulate a nonlinear estimation problem based on an analytical model for the dipole-generated flow field. Two algorithms are presented to estimate both the source location and the vibration amplitude, one based on the least squares method and the other based on the Newton-Raphson method. Simulation results show that both methods deliver comparable performance in source localization. A prototype of artificial lateral line system comprising four ionic polymer-metal composite (IPMC) sensors is built, and experimental results are further presented to demonstrate the effectiveness of IPMC lateral line systems and the proposed estimation algorithms.

Flow of ultra-hot Precambrian orogens and the making of crustal layering in Phanerozoic orogenic plateaux

NASA Astrophysics Data System (ADS)

Chardon, Dominique; Gapais, Denis; Cagnard, Florence; Jayananda, Mudlappa; Peucat, Jean-Jacques

2010-05-01

Reassessment of structural / metamorphic properties of ultra-hot Precambrian orogens and shortening of model weak lithospheres support a syn-convergence flow mode on an orogen scale, with a large component of horizontal finite elongation parallel to the orogen. This orogen-scale flow mode combines distributed shortening, gravity-driven flow, lateral escape, and three-dimensional mass redistribution of buried supracrustal rocks, magmas and migmatites in a thick fluid lower crust. This combination preserves a nearly flat surface and Moho. The upper crust maintains a nearly constant thickness by real-time erosion and near-field clastic sedimentation and by ablation at its base by burial of pop-downs into the lower crust. Steady state regime of these orogens is allowed by activation of an attachment layer that maintains kinematic compatibility between the thin and dominantly plastic upper crust and a thick "water bed" of lower crust. Because very thin lithospheres of orogenic plateaux and Precambrian hot orogens have similar thermomechanical structures, bulk orogenic flow comparable to that governing Precambrian hot orogens should actually operate through today's orogenic plateaux as well. Thus, syn-convergence flow fabrics documented on exposed crustal sections of ancient hot orogens that have not undergone collapse may be used to infer the nature of flow fabrics that are imaged by geophysical techniques beneath orogenic plateaux. We provide a detailed geological perspective on syn-convergence crustal flow in relation to magma emplacement and partial melting on a wide oblique crustal transition of the Neoarchean ultra-hot orogen of Southern India. We document sub-horizontal bulk longitudinal flow of the partially molten lower crust over a protracted period of 60 Ma. Bulk flow results from the interplay of (1) pervasive longitudinal transtensional flow of the partially molten crust, (2) longitudinal coaxial flow on flat fabrics in early plutons, (3) distributed, orogen-normal shortening, (4) emplacement of late prolate shape plutons in the direction of flow, and (5) late, conjugate strike-slip shearing. The macroscopic- to regional scale tectonoplutonic pattern produced by longitudinal flow forms a flat composite anisotropy throughout the lower crust. In the light of GPS data, these results suggest that bulk longitudinal flow accounts for observed deformation of the Tibetan plateau as well as for its seismic structure. This flow mode may be preferred to lateral, east-directed channel flow because it combines both lateral gravity-driven thinning and distributed, orogen-normal shortening of the crust. These results further suggest that lower crustal seismic reflectivity in orogenic belts may not necessarily images fabrics produced by extensional tectonics, as commonly thought, but crustal layering produced by syn-convergence lateral flow.

Influence of vertical and lateral heat transfer on permafrost thaw, peatland landscape transition, and groundwater flow

USGS Publications Warehouse

Kurylyk, Barret L.; Masaki, Masaki; Quinton, William L.; McKenzie, Jeffrey M.; Voss, Clifford I.

2016-01-01

Recent climate change has reduced the spatial extent and thickness of permafrost in many discontinuous permafrost regions. Rapid permafrost thaw is producing distinct landscape changes in the Taiga Plains of the Northwest Territories, Canada. As permafrost bodies underlying forested peat plateaus shrink, the landscape slowly transitions into unforested wetlands. The expansion of wetlands has enhanced the hydrologic connectivity of many watersheds via new surface and near-surface flow paths, and increased streamflow has been observed. Furthermore, the decrease in forested peat plateaus results in a net loss of boreal forest and associated ecosystems. This study investigates fundamental processes that contribute to permafrost thaw by comparing observed and simulated thaw development and landscape transition of a peat plateau-wetland complex in the Northwest Territories, Canada from 1970 to 2012. Measured climate data are first used to drive surface energy balance simulations for the wetland and peat plateau. Near-surface soil temperatures simulated in the surface energy balance model are then applied as the upper boundary condition to a three-dimensional model of subsurface water flow and coupled energy transport with freeze-thaw. Simulation results demonstrate that lateral heat transfer, which is not considered in many permafrost models, can influence permafrost thaw rates. Furthermore, the simulations indicate that landscape evolution arising from permafrost thaw acts as a positive feedback mechanism that increases the energy absorbed at the land surface and produces additional permafrost thaw. The modeling results also demonstrate that flow rates in local groundwater flow systems may be enhanced by the degradation of isolated permafrost bodies.

Estimating the Natural Flow Regime of Rivers With Long-Standing Development: The Northern Branch of the Rio Grande

NASA Astrophysics Data System (ADS)

Blythe, Todd L.; Schmidt, John C.

2018-02-01

An estimate of a river's natural flow regime is useful for water resource planning and ecosystem rehabilitation by providing insight into the predisturbance form and function of a river. The natural flow regime of most rivers has been perturbed by development during the 20th century and in some cases, before stream gaging began. The temporal resolution of natural flows estimated using traditional methods is typically not sufficient to evaluate cues that drive native ecosystem function. Additionally, these traditional methods are watershed specific and require large amounts of data to produce accurate results. We present a mass balance method that estimates natural flows at daily time step resolution for the northern branch of the Rio Grande, upstream from the Rio Conchos, that relies only on easily obtained streamflow data. Using an analytical change point method, we identified periods of the measured flow regime during the 20th century for comparison with the estimated natural flows. Our results highlight the significant deviation from natural conditions that occurred during the 20th century. The total annual flow of the northern branch is 95% lower than it would be in the absence of human use. The current 2 year flood has decreased by more than 60%, is shorter in duration, and peaks later in the year. When compared to unregulated flows estimated using traditional mass balance accounting methods, our approach provides similar results.

ULTRASTRUCTURAL STUDIES OF VASOPRESSIN EFFECT ON ISOLATED PERFUSED RENAL COLLECTING TUBULES OF THE RABBIT

PubMed Central

Ganote, Charles E.; Grantham, Jared J.; Moses, Harold L.; Burg, Maurice B.; Orloff, Jack

1968-01-01

Isolated cortical collecting tubules from rabbit kidney were studied during perfusion with solutions made either isotonic or hypotonic to the external bathing medium. Examination of living tubules revealed a reversible increase in thickness of the cellular layer, prominence of lateral cell membranes, and formation of intracellular vacuoles during periods of vasopressin-induced osmotic water transport. Examination in the electron microscope revealed that vasopressin induced no changes in cell structure in collecting tubules in the absence of an osmotic difference and significant bulk water flow across the tubule wall. In contrast, tubules fixed during vasopressin-induced periods of high osmotic water transport showed prominent dilatation of lateral intercellular spaces, bulging of apical cell membranes into the tubular lumen, and formation of intracellular vacuoles. It is concluded that the ultrastructural changes are secondary to transepithelial bulk water flow and not to a direct effect of vasopressin on the cells, and that vasopressin induces osmotic flow by increasing water permeability of the luminal cell membrane. The lateral intercellular spaces may be part of the pathway for osmotically induced transepithelial bulk water flow. PMID:4867134

Numerical simulation of the pairwise interaction of deformable cells during migration in a microchannel

NASA Astrophysics Data System (ADS)

Lan, Hongzhi; Khismatullin, Damir B.

2014-07-01

Leukocytes and other circulating cells deform and move relatively to the channel flow in the lateral and translational directions. Their migratory property is important in immune response, hemostasis, cancer progression, delivery of nutrients, and microfluidic technologies such as cell separation and enrichment, and flow cytometry. Using our three-dimensional computational algorithm for multiphase viscoelastic flow, we have investigated the effect of pairwise interaction on the lateral and translational migration of circulating cells in a microchannel. The numerical simulation data show that when two cells with the same size and small separation distance interact, repulsive interaction take place until they reach the same lateral equilibrium position. During this process, they undergo swapping or passing, depending on the initial separation distance between each other. The threshold value of this distance increases with cell deformation, indicating that the cells experiencing larger deformation are more likely to swap. When a series of closely spaced cells with the same size are considered, they generally undergo damped oscillation in both lateral and translational directions until they reach equilibrium positions where they become evenly distributed in the flow direction (self-assembly phenomenon). A series of cells with a large lateral separation distance could collide repeatedly with each other, eventually crossing the centerline and entering the other side of the channel. For a series of cells with different deformability, more deformable cells, upon impact with less deformable cells, move to an equilibrium position closer to the centerline. The results of our study show that the bulk deformation of circulating cells plays a key role in their migration in a microchannel.

Revisiting directed flow in relativistic heavy-ion collisions from a multiphase transport model

NASA Astrophysics Data System (ADS)

Guo, Chong-Qiang; Zhang, Chun-Jian; Xu, Jun

2017-12-01

We have revisited several interesting questions on how the rapidity-odd directed flow is developed in relativistic 197Au+197Au collisions at √{s_{NN}} = 200 and 39 GeV based on a multiphase transport model. As the partonic phase evolves with time, the slope of the parton directed flow at midrapidity region changes from negative to positive as a result of the later dynamics at 200 GeV, while it remains negative at 39 GeV due to the shorter life time of the partonic phase. The directed flow splitting for various quark species due to their different initial eccentricities is observed at 39 GeV, while the splitting is very small at 200GeV. From a dynamical coalescence algorithm with Wigner functions, we found that the directed flow of hadrons is a result of competition between the coalescence in momentum and coordinate space as well as further modifications by the hadronic rescatterings.

Hydrodynamic interaction of two deformable drops in confined shear flow.

PubMed

Chen, Yongping; Wang, Chengyao

2014-09-01

We investigate hydrodynamic interaction between two neutrally buoyant circular drops in a confined shear flow based on a computational fluid dynamics simulation using the volume-of-fluid method. The rheological behaviors of interactive drops and the flow regimes are explored with a focus on elucidation of underlying physical mechanisms. We find that two types of drop behaviors during interaction occur, including passing-over motion and reversing motion, which are governed by the competition between the drag of passing flow and the entrainment of reversing flow in matrix fluid. With the increasing confinement, the drop behavior transits from the passing-over motion to reversing motion, because the entrainment of the reversing-flow matrix fluid turns to play the dominant role. The drag of the ambient passing flow is increased by enlarging the initial lateral separation due to the departure of the drop from the reversing flow in matrix fluid, resulting in the emergence of passing-over motion. In particular, a corresponding phase diagram is plotted to quantitatively illustrate the dependence of drop morphologies during interaction on confinement and initial lateral separation.

[The effects of carbogen inhalation on microvascular within lateral wall of cochlear following acute acoustic trauma].

PubMed

Zhao, Jing; Sun, Jianjun; Kong, Weijia

2008-11-01

To explore the influence of carbogen on lateral wall microvascular of cochlear after acute acoustic trauma. Forty guinea pigs were divided into 4 groups: group A (noise damage), group B (carbogen inhalation), group C (noise damage + carbogen inhalation), and the control group without any treatment. The diameter of the column of RBCs (RBC column diameter, RBCCD), blood flow velocity (BFV) and blood flow states(BFS) in microvasculature were measured and described under microscope. The microvascular in group A demonstrated a blood flow in contrary direction, granuliform flow, and granular slow flow. The erythrocytes aggregated in the microvascular of the cochlea. The RBCCD decreased 12.1% compared with the control group (P < 0.05). The blood flow in group B showed a laminar flow or laminar granular flow, and the RBCCD increased 20.7% compared with the control group. The blood condition in group C was the same as the control group-laminar granular blood flow; the blood flow with contrary direction was less than group A, and the RBCCD was 17.4% lager than that of group A. Carbogen can dilate the RBCCD and increase the BFV in stria vascular. So carbogen can alleviate the harm from noise.

Corium shield

DOEpatents

McDonald, Douglas B.; Buchholz, Carol E.

1994-01-01

A shield for restricting molten corium from flowing into a water sump disposed in a floor of a containment vessel includes upper and lower walls which extend vertically upwardly and downwardly from the floor for laterally bounding the sump. The upper wall includes a plurality of laterally spaced apart flow channels extending horizontally therethrough, with each channel having a bottom disposed coextensively with the floor for channeling water therefrom into the sump. Each channel has a height and a length predeterminedly selected for allowing heat from the molten corium to dissipate through the upper and lower walls as it flows therethrough for solidifying the molten corium therein to prevent accumulation thereof in the sump.

Development of a duplex lateral flow assay for simultaneous detection of antibodies against African and Classical swine fever viruses.

PubMed

Sastre, Patricia; Pérez, Teresa; Costa, Sofia; Yang, Xiaoping; Räber, Alex; Blome, Sandra; Goller, Katja V; Gallardo, Carmina; Tapia, Istar; García, Julia; Sanz, Antonio; Rueda, Paloma

2016-09-01

Classical swine fever (CSF) and African swine fever (ASF) are both highly contagious diseases of domestic pigs and wild boar and are clinically indistinguishable. For both diseases, antibody detection is an integral and crucial part of prevention and control measures. The purpose of our study was to develop and initially validate a duplex pen-side test for simultaneous detection and differentiation of specific antibodies against CSF virus (CSFV) and ASF virus (ASFV). The test was based on the major capsid protein VP72 of ASFV and the structural protein E2 of CSFV, both considered the most immunogenic proteins of these viruses. The performance of the pen-side test was evaluated using a panel of porcine samples consisting of experimental, reference, and field sera, with the latter collected from European farms free of both diseases. The new lateral flow assay was able to detect specific antibodies to ASFV or CSFV, showing good levels of sensitivity and specificity. These preliminary data indicate the potential of the newly developed pen-side test for rapid differential detection of antibodies found in the 2 diseases, which is of particular importance in the field and in front-line laboratories where equipment and skilled personnel are limited and control of ASF and CSF is crucial. © 2016 The Author(s).

Development of a rapid and visual nucleotide detection method for a Chinese epidemic strain of Orientia tsutsugamushi based on recombinase polymerase amplification assay and lateral flow test.

PubMed

Qi, Yong; Yin, Qiong; Shao, Yinxiu; Cao, Min; Li, Suqin; Chen, Hongxia; Shen, Wanpeng; Rao, Jixian; Li, Jiameng; Li, Xiaoling; Sun, Yu; Lin, Yu; Deng, Yi; Zeng, Wenwen; Zheng, Shulong; Liu, Suyun; Li, Yuexi

2018-05-01

Orientia tsutsugamushi is an obligate intracellular pathogen that causes scrub typhus. Diagnosing scrub typhus remains a challenge, and a sensitive, specific, simple, and rapid diagnostic test is still needed. A recombinase polymerase amplification (RPA) assay combined with a lateral flow (LF) test targeting the 56-kDa gene of a Karp-like strain of O. tsutsugamushi was developed and optimized. The detection limits, sensitivity, specificity, and simulative clinical performance were evaluated. Primers and probe were screened to establish the RPA assay, and the reaction conditions were optimized. The detection limit was 10 copies/reaction in detecting plasmid DNA and 12 copies/reaction in detecting genomic DNA. The RPA-LF method could differentiate O. tsutsugamushi from other phylogenetically related bacteria. The sensitivity was 100% and specificity was over 90%, when evaluated using infected animal samples or simulative clinical samples. Furthermore, the method was completed in 20min at 37°C followed by a 3-5min incubation at room temperature for the development of an immunochromatographic strip, and the results could be determined visually. This method is promising for wide-ranging use in basic medical units considering that it requires minimal instruments and infrastructure and is highly time-efficient, sensitive, and specific for diagnosing scrub typhus. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Denitrification in the Mississippi River network controlled by flow through river bedforms

USGS Publications Warehouse

Gomez-Velez, Jesus D.; Harvey, Judson W.; Cardenas, M. Bayani; Kiel, Brian

2015-01-01

Increasing nitrogen concentrations in the world’s major rivers have led to over-fertilization of sensitive downstream waters1, 2, 3, 4. Flow through channel bed and bank sediments acts to remove riverine nitrogen through microbe-mediated denitrification reactions5, 6, 7, 8, 9, 10. However, little is understood about where in the channel network this biophysical process is most efficient, why certain channels are more effective nitrogen reactors, and how management practices can enhance the removal of nitrogen in regions where water circulates through sediment and mixes with groundwater - hyporheic zones8, 11, 12. Here we present numerical simulations of hyporheic flow and denitrification throughout the Mississippi River network using a hydrogeomorphic model. We find that vertical exchange with sediments beneath the riverbed in hyporheic zones, driven by submerged bedforms, has denitrification potential that far exceeds lateral hyporheic exchange with sediments alongside river channels, driven by river bars and meandering banks. We propose that geomorphic differences along river corridors can explain why denitrification efficiency varies between basins in the Mississippi River network. Our findings suggest that promoting the development of permeable bedforms at the streambed - and thus vertical hyporheic exchange - would be more effective at enhancing river denitrification in large river basins than promoting lateral exchange through induced channel meandering. 

Improved Analytical Sensitivity of Lateral Flow Assay using Sponge for HBV Nucleic Acid Detection.

PubMed

Tang, Ruihua; Yang, Hui; Gong, Yan; Liu, Zhi; Li, XiuJun; Wen, Ting; Qu, ZhiGuo; Zhang, Sufeng; Mei, Qibing; Xu, Feng

2017-05-02

Hepatitis B virus (HBV) infection is a serious public health problem, which can be transmitted through various routes (e.g., blood donation) and cause hepatitis, liver cirrhosis and liver cancer. Hence, it is necessary to do diagnostic screening for high-risk HBV patients in these transmission routes. Nowadays, protein-based technologies have been used for HBV testing, which however involve the issues of large sample volume, antibody instability and poor specificity. Nucleic acid hybridization-based lateral flow assay (LFA) holds great potential to address these limitations due to its low-cost, rapid, and simple features, but the poor analytical sensitivity of LFA restricts its application. In this study, we developed a low-cost, simple and easy-to-use method to improve analytical sensitivity by integrating sponge shunt into LFA to decrease the fluid flow rate. The thickness, length and hydrophobicity of the sponge shunt were sequentially optimized, and achieved 10-fold signal enhancement in nucleic acid testing of HBV as compared to the unmodified LFA. The enhancement was further confirmed by using HBV clinical samples, where we achieved the detection limit of 10 3 copies/ml as compared to 10 4 copies/ml in unmodified LFA. The improved LFA holds great potential for diseases diagnostics, food safety control and environment monitoring at point-of-care.

Lateral Downflows in Sunspot Penumbral Filaments and their Temporal Evolution

NASA Astrophysics Data System (ADS)

Esteban Pozuelo, S.; Bellot Rubio, L. R.; de la Cruz Rodríguez, J.

2015-04-01

We study the temporal evolution of downflows observed at the lateral edges of penumbral filaments in a sunspot located very close to the disk center. Our analysis is based on a sequence of nearly diffraction-limited scans of the Fe i 617.3 nm line taken with the CRisp Imaging Spectro-Polarimeter instrument at the Swedish 1 m Solar Telescope. We compute Dopplergrams from the observed intensity profiles using line bisectors and filter the resulting velocity maps for subsonic oscillations. Lateral downflows appear everywhere in the center-side penumbra as small, weak patches of redshifts next to or along the edges of blueshifted flow channels. These patches have an intermittent life and undergo mergings and fragmentations quite frequently. The lateral downflows move together with the hosting filaments and react to their shape variations, very much resembling the evolution of granular convection in the quiet Sun. There is a good relation between brightness and velocity in the center-side penumbra, with downflows being darker than upflows on average, which is again reminiscent of quiet Sun convection. These results point to the existence of overturning convection in sunspot penumbrae, with elongated cells forming filaments where the flow is upward but very inclined, and weak lateral downward flows. In general, the circular polarization profiles emerging from the lateral downflows do not show sign reversals, although sometimes we detect three-lobed profiles that are suggestive of opposite magnetic polarities in the pixel.

Venous flow during manual lymphatic drainage applied to different regions of the lower extremity in people with and without chronic venous insufficiency: a cross-sectional study.

PubMed

Crisóstomo, R S S; Candeias, M S; Armada-da-Silva, P A S

2017-03-01

To evaluate the effect of manual lymphatic drainage (MLD) on venous flow when applied to the medial and lateral aspects of the thigh and leg in patients with chronic venous insufficiency (CVI) and healthy subjects. Cross-sectional study. Participants were assessed in a school-based health community attendant service. Fifty-seven subjects participated in this study {mean age: 43 [standard deviation (SD) 14] years, 38 women and 19 men}. Of these, 28 subjects had CVI [mean age 47 (SD 12) years] and 29 subjects did not have CVI [mean age 39 (14) years]. MLD was applied by a certificated physical therapist to the medial and lateral aspects of the thigh and leg. Cross-sectional area; blood flow velocities in the femoral vein, great saphenous vein, popliteal vein and small saphenous vein at baseline and during MLD, measured by duplex ultrasound. Flow volume in the femoral vein increased from baseline [5.19 (SD 3.25)cm 3 /second] when MLD was applied to the medial [7.03 (SD 3.65)cm 3 /second; P≤0.001; mean difference -1.69; 95% confidence interval (CI) -2.42 to -0.97] and lateral [6.16 (SD 3.35)cm 3 /second; P≤0.001; mean difference -1.04; 95% CI -1.70 to -0.39] aspects of the thigh. Venous flow augmentation in the femoral vein and great saphenous vein was higher when MLD was applied to the medial aspect of the thigh (P<0.001), while MLD had a similar effect on venous blood flow regardless of whether it was applied to the medial or the lateral aspect of the leg (P=0.731). MLD increases blood flow in deep and superficial veins. MLD should be applied along the route of the venous vessels for improved venous return. Copyright © 2016 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

Quantifiable Lateral Flow Assay Test Strips

NASA Technical Reports Server (NTRS)

2003-01-01

As easy to read as a home pregnancy test, three Quantifiable Lateral Flow Assay (QLFA) strips used to test water for E. coli show different results. The brightly glowing control line on the far right of each strip indicates that all three tests ran successfully. But the glowing test line on the middle left and bottom strips reveal their samples were contaminated with E. coli bacteria at two different concentrations. The color intensity correlates with concentration of contamination.

Influence of lateral discomfort on the stability of traffic flow based on visual angle car-following model

NASA Astrophysics Data System (ADS)

Zheng, Liang; Zhong, Shiquan; Jin, Peter J.; Ma, Shoufeng

2012-12-01

Due to the poor road markings and irregular driving behaviors, not every vehicle is positioned in the center of the lane. The deviation from the center can cause discomfort to drivers in the neighboring lane, which is referred to as lateral discomfort (or lateral friction). Such lateral discomfort can be incorporated into the driver stimulus-response framework by considering the visual angle and its changing rate from the psychological viewpoint. In this study, a two-lane visual angle based car-following model is proposed and its stability condition is obtained through linear stability theory. Further derivations indicate that the neutral stability line of the model is asymmetry and four factors including the vehicle width and length, the lateral separation and the sensitivity regarding the changing rate of visual angle have large impacts on the stability of traffic flow. Numerical simulations further verify these theoretical results, and demonstrate that the behaviors of diverging, merging and lane changing can break the original steady state and cause traffic fluctuations. However, these fluctuations may be alleviated to some extent by reducing the lateral discomfort.

Analysis of Dynamic Avalanche Phenomenon in SOI Lateral High-speed Diode during Reverse Recovery and Development of a Novel Device Structure for Suppressing Dynamic Avalanche

NASA Astrophysics Data System (ADS)

Tokura, Norihito; Yamamoto, Takao; Kato, Hisato; Nakagawa, Akio

We have studied the dynamic avalanche phenomenon in an SOI lateral diode during reverse recovery by using a mixed-mode device simulation. In the study, it has been found that local impact ionization occurs near an anode-side field oxide edge, where a high-density hole current flows and a high electric field appears simultaneously. We propose that a p-type anode extension region (AER) along a trench side wall effectively sweeps out stored carriers beneath an anode p-diffusion layer during reverse recovery, resulting in reduction of the electric field and remarkable suppression of the dynamic avalanche. The AER reduces the total recovery charge and does not cause any increase in the total stored charge under a forward bias operation. This effect is verified experimentally by the fabricated device with AER. Thus, the developed SOI lateral diode is promising as a high-speed and highly rugged free-wheeling diode, which can be integrated into next-generation SOI microinverters.

Vortex shedding within laminar separation bubbles forming over an airfoil

NASA Astrophysics Data System (ADS)

Kirk, Thomas M.; Yarusevych, Serhiy

2017-05-01

Vortex shedding within laminar separation bubbles forming over the suction side of a NACA 0018 airfoil is studied through a combination of high-speed flow visualization and boundary layer measurements. Wind tunnel experiments are performed at a chord-based Reynolds number of 100,000 and four angles of attack. The high-speed flow visualization is complemented by quantitative velocity and surface pressure measurements. The structures are shown to originate from the natural amplification of small-amplitude disturbances, and the shear layer roll-up is found to occur coherently across the span. However, significant cycle-to-cycle variations are observed in vortex characteristics, including shedding period and roll-up location. The formation of the roll-up vortices precedes the later stages of transition, during which these structures undergo significant deformations and breakdown to smaller scales. During this stage of flow development, vortex merging is also observed. The results provide new insight into the development of coherent structures in separation bubbles and their relation to the overall bubble dynamics and mean bubble topology.

Identification of runoff formation with two dyes in a mid-latitude mountain headwater

NASA Astrophysics Data System (ADS)

Vlček, Lukáš; Falátková, Kristýna; Schneider, Philipp

2017-06-01

Subsurface flow in peat bog areas and its role in the hydrologic cycle has garnered increased attention as water scarcity and floods have increased due to a changing climate. In order to further probe the mechanisms in peat bog areas and contextualize them at the catchment scale, this experimental study identifies runoff formation at two opposite hillslopes in a peaty mountain headwater; a slope with organic peat soils and a shallow phreatic zone (0.5 m below surface), and a slope with mineral Podzol soils and no detectable groundwater (> 2 m below surface). Similarities and differences in infiltration, percolation and preferential flow paths between both hillslopes could be identified by sprinkling experiments with Brilliant Blue and Fluorescein sodium. To our knowledge, this is the first time these two dyes have been compared in their ability to stain preferential flow paths in soils. Dye-stained soil profiles within and downstream of the sprinkling areas were excavated parallel (lateral profiles) and perpendicular (frontal profiles) to the slopes' gradients. That way preferential flow patterns in the soil could be clearly identified. The results show that biomat flow, shallow subsurface flow in the organic topsoil layer, occurred at both hillslopes; however, at the peat bog hillslope it was significantly more prominent. The dye solutions infiltrated into the soil and continued either as lateral subsurface pipe flow in the case of the peat bog, or percolated vertically towards the bedrock in the case of the Podzol. This study provides evidence that subsurface pipe flow, lateral preferential flow along decomposed tree roots or logs in the unsaturated zone, is a major runoff formation process at the peat bog hillslope and in the adjacent riparian zone.

Vadose Zone Transport Field Study: Summary Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, Andy L.; Conrad, Mark E.; Daily, William D.

2006-07-31

From FY 2000 through FY 2003, a series of vadose zone transport field experiments were conducted as part of the U.S. Department of Energy’s Groundwater/Vadose Zone Integration Project Science and Technology Project, now known as the Remediation and Closure Science Project, and managed by the Pacific Northwest National Laboratory (PNNL). The series of experiments included two major field campaigns, one at a 299-E24-11 injection test site near PUREX and a second at a clastic dike site off Army Loop Road. The goals of these experiments were to improve our understanding of vadose zone transport processes; to develop data sets tomore » validate and calibrate vadose zone flow and transport models; and to identify advanced monitoring techniques useful for evaluating flow-and-transport mechanisms and delineating contaminant plumes in the vadose zone at the Hanford Site. This report summarizes the key findings from the field studies and demonstrates how data collected from these studies are being used to improve conceptual models and develop numerical models of flow and transport in Hanford’s vadose zone. Results of these tests have led to a better understanding of the vadose zone. Fine-scale geologic heterogeneities, including grain fabric and lamination, were observed to have a strong effect on the large-scale behavior of contaminant plumes, primarily through increased lateral spreading resulting from anisotropy. Conceptual models have been updated to include lateral spreading and numerical models of unsaturated flow and transport have revised accordingly. A new robust model based on the concept of a connectivity tensor was developed to describe saturation-dependent anisotropy in strongly heterogeneous soils and has been incorporated into PNNL’s Subsurface Transport Over Multiple Phases (STOMP) simulator. Application to field-scale transport problems have led to a better understanding plume behavior at a number of sites where lateral spreading may have dominated waste migration (e.g. BC Cribs and Trenches). The improved models have been also coupled with inverse models and newly-developed parameter scaling techniques to allow estimation of field-scale and effective transport parameters for the vadose zone. The development and utility of pedotransfer functions for describing fine-scale hydrogeochemical heterogeneity and for incorporating this heterogeneity into reactive transport models was explored. An approach based on grain-size statistics appears feasible and has been used to describe heterogeneity in hydraulic properties and sorption properties, such as the cation exchange capacity and the specific surface area of Hanford sediments. This work has also led to the development of inverse modeling capabilities for time-dependent, subsurface, reactive transport with transient flow fields using an automated optimization algorithm. In addition, a number of geophysical techniques investigated for their potential to provide detailed information on the subtle changes in lithology and bedding surfaces; plume delineation, leak detection. High-resolution resistivity is now being used for detecting saline plumes at several waste sites at Hanford, including tank farms. Results from the field studies and associated analysis have appeared in more than 46 publications generated over the past 4 years. These publications include test plans and status reports, in addition to numerous technical notes and peer reviewed papers.« less

The investigation of the lateral interaction effect's on traffic flow behavior under open boundaries

NASA Astrophysics Data System (ADS)

Bouadi, M.; Jetto, K.; Benyoussef, A.; El Kenz, A.

2017-11-01

In this paper, an open boundaries traffic flow system is studied by taking into account the lateral interaction with spatial defects. For a random defects distribution, if the vehicles velocities are weakly correlated, the traffic phases can be predicted by considering the corresponding inflow and outflow functions. Conversely, if the vehicles velocities are strongly correlated, a phase segregation appears inside the system's bulk which induces the maximum current appearance. Such velocity correlation depends mainly on the defects densities and the probabilities of lateral deceleration. However, for a compact defects distribution, the traffic phases are predictable by using the inflow in the system beginning, the inflow entering the defects zone and the outflow function.

Subaqueous ice-contact fans: Depositional systems characterised by highly aggradational supercritical flow conditions

NASA Astrophysics Data System (ADS)

Lang, Joerg; Winsemann, Jutta

2015-04-01

Subaqueous ice-contact fans are deposited by high-energy plane-wall jets from subglacial conduits into standing water bodies. Highly aggradational conditions during flow expansion and deceleration allow for the preservation of bedforms related to supercritical flows, which are commonly considered rare in the depositional record. We present field examples from gravelly and sandy subaqueous ice-contact fan successions, which indicate that deposition by supercritical flows might be considered as a characteristic feature of these depositional systems. The studied successions were deposited in deep ice-dammed lakes, which formed along the margins of the Middle Pleistocene Scandinavian ice sheets across Northern Germany. The gravel-rich subaqueous fan deposits are dominated by large scour-fills (up to 25 m wide and 3 m) deep and deposits of turbulent hyperconcentrated flows, which are partly attributed to supercritical flow conditions (Winsemann et al., 2009). Scours (up to 4.5 m wide and 0.9 m deep) infilled by gravelly backsets are observed above laterally extensive erosional surfaces and are interpreted as deposits of cyclic steps. Laterally discontinuous beds of low-angle cross-stratified gravel are interpreted as antidune deposits. Downflow and up-section the gravel-rich deposits pass into sand-rich successions, which include deposits of chutes-and-pools, breaking antidunes, stationary antidunes and humpback dunes (Lang and Winsemann, 2013). Deposits of chutes-and-pools and breaking antidunes are characterised by scour-fills (up to 4 m wide and 1.2 m deep) comprising backsets or gently dipping sigmoidal foresets. Stationary antidune deposits consist of laterally extensive sinusoidal waveforms with long wavelengths (1-12 m) and low amplitudes (0.1-0.5 m), which formed under quasi-steady flows at the lower limit of the supercritical flow stage and high rates of sedimentation. Humpback dunes are characterised by divergent sigmoidal foresets and are interpreted as bedforms related to transcritical flow conditions. Deposits of aggrading stationary antidunes and humpback dunes represent a characteristic facies association of the distal zone of flow transition. Downflow the succession passes into deposits of large 3D dunes and climbing ripples. The large-scale lateral and vertical successions of bedforms are interpreted as representing the temporal and spatial evolution of the supercritical meltwater jets, which was affected by hydraulic jumps. Small-scale facies changes and the formation of individual bedforms are interpreted as controlled by fluctuating discharge, pulsating unstable flows and bed topography. References: Lang, J., Winsemann, J. (2013) Lateral and vertical facies relationships of bedforms deposited by aggrading supercritical flows: from cyclic steps to humpback dunes. Sedimentary Geology 296, 36-54. Winsemann, J., Hornung, J.J., Meinsen, J., Asprion, U., Polom, U., Brandes, C., Bussmann, M., Weber, C., (2009) Anatomy of a subaqueous ice-contact fan and delta complex, Middle Pleistocene, North-west Germany, Sedimentology 56, 1041-1076.

Thin and open vessel windows for intra-vital fluorescence imaging of murine cochlear blood flow

PubMed Central

Shi, Xiaorui; Zhang, Fei; Urdang, Zachary; Dai, Min; Neng, Lingling; Zhang, Jinhui; Chen, Songlin; Ramamoorthy, Sripriya; Nuttall, Alfred L.

2014-01-01

Normal microvessel structure and function in the cochlea is essential for maintaining the ionic and metabolic homeostasis required for hearing function. Abnormal cochlear microcirculation has long been considered an etiologic factor in hearing disorders. A better understanding of cochlear blood flow (CoBF) will enable more effective amelioration of hearing disorders that result from aberrant blood flow. However, establishing the direct relationship between CoBF and other cellular events in the lateral wall and response to physio-pathological stress remains a challenge due to the lack of feasible interrogation methods and difficulty in accessing the inner ear. Here we report on new methods for studying the CoBF in a mouse model using a thin or open vessel-window in combination with fluorescence intra-vital microscopy (IVM). An open vessel-window enables investigation of vascular cell biology and blood flow permeability, including pericyte (PC) contractility, bone marrow cell migration, and endothelial barrier leakage, in wild type and fluorescent protein-labeled transgenic mouse models with high spatial and temporal resolution. Alternatively, the thin vessel-window method minimizes disruption of the homeostatic balance in the lateral wall and enables study CoBF under relatively intact physiological conditions. A thin vessel-window method can also be used for time-based studies of physiological and pathological processes. Although the small size of the mouse cochlea makes surgery difficult, the methods are sufficiently developed for studying the structural and functional changes in CoBF under normal and pathological conditions. PMID:24780131

Towards a high resolution, integrated hydrology model of North America: Diagnosis of feedbacks between groundwater and land energy fluxes at continental scales.

NASA Astrophysics Data System (ADS)

Maxwell, Reed; Condon, Laura

2016-04-01

Recent studies demonstrate feedbacks between groundwater dynamics, overland flow, land surface and vegetation processes, and atmospheric boundary layer development that significantly affect local and regional climate across a range of climatic conditions. Furthermore, the type and distribution of vegetation cover alters land-atmosphere water and energy fluxes, as well as runoff generation and overland flow processes. These interactions can result in significant feedbacks on local and regional climate. In mountainous regions, recent research has shown that spatial and temporal variability in annual evapotranspiration, and thus water budgets, is strongly dependent on lateral groundwater flow; however, the full effects of these feedbacks across varied terrain (e.g. from plains to mountains) are not well understood. Here, we present a high-resolution, integrated hydrology model that covers much of continental North America and encompasses the Mississippi and Colorado watersheds. The model is run in a fully-transient manner at hourly temporal resolution incorporating fully-coupled land energy states and fluxes with integrated surface and subsurface hydrology. Connections are seen between hydrologic variables (such as water table depth) and land energy fluxes (such as latent heat) and spatial and temporal scaling is shown to span many orders of magnitude. Model results suggest that partitioning of plant transpiration to bare soil evaporation is a function of water table depth and later groundwater flow. Using these transient simulations as a proof of concept, we present a vision for future integrated simulation capabilities.

3D Modeling of the Deep Groundwater System at Mount Shasta, California, Using Finite Difference and Inverse Modeling in Combination with Magnetotellurics

NASA Astrophysics Data System (ADS)

Webb, C. H.; Foglia, L.; Fogg, G. E.; McClain, J.

2017-12-01

Precipitation in mountainous systems is responsible for much of the world's freshwater supply. Volcanic mountains in particular may have the capacity to store large amounts of groundwater, due to the relatively high permeability of volcanic rocks as compared to fractured crystalline rocks. These qualities make volcanic aquifers likely candidates for laterally extensive deep groundwater systems. However, the depth extent of these aquifers is not well understood and has been little studied, due to the dearth of well data in most mountain systems. When determining a water budget, especially for mountainous regions, it is necessary to understand the extent of the entire system, including the deep components. Mount Shasta of the California cascade volcanoes is one potential case of a deep groundwater system with the capacity to store significant amounts of water. In order to develop a conceptual model of the role of deep and regional groundwater flow in the Mt. Shasta groundwater system, the region was modeled using MODFLOW_2005, the finite difference flow model developed by USGS. The model was constrained using SRTM topography data, spring flow rates, PRISM precipitation rates, and well log levels. Geologic cross sections and gravity data were referenced in order to create a realistic estimate of the aquifer's structure down to 6km in depth. The aquifer stratigraphy was then represented by using 6 layers with 2-4 zones of hydraulic conductivity per layer to account for both vertical and lateral differences in lithology as well as decreasing permeability with depth. These hydraulic conductivity parameters of the model were varied using inverse modeling (UCODE_2014) to determine which layers and zones could support flow and still produce results consistent with existing well logs. Depth of flow was also corroborated with resistivity data collected in Shasta Valley using magnetotelluric (MT) soundings. Depths with comparatively low electrical resistivity were assumed to be aquifer units, and zones with high resistivity were assumed to be aquitards. By performing MT soundings in multiple locations and dividing the model into zones, this model tests both the maximum depth of flow as well as how that depth varies with lithology and geographical location.

Documentation of the Santa Clara Valley regional ground-water/surface-water flow model, Santa Clara Valley, California

USGS Publications Warehouse

Hanson, R.T.; Li, Zhen; Faunt, C.C.

2004-01-01

The Santa Clara Valley is a long, narrow trough extending about 35 miles southeast from the southern end of San Francisco Bay where the regional alluvial-aquifer system has been a major source of water. Intensive agricultural and urban development throughout the 20th century and related ground-water development resulted in ground-water-level declines of more than 200 feet and land subsidence of as much as 12.7 feet between the early 1900s and the mid-1960s. Since the 1960s, Santa Clara Valley Water District has imported surface water to meet growing demands and reduce dependence on ground-water supplies. This importation of water has resulted in a sustained recovery of the ground-water flow system. To help support effective management of the ground-water resources, a regional ground-water/surface-water flow model was developed. This model simulates the flow of ground water and surface water, changes in ground-water storage, and related effects such as land subsidence. A numerical ground-water/surface-water flow model of the Santa Clara Valley subbasin of the Santa Clara Valley was developed as part of a cooperative investigation with the Santa Clara Valley Water District. The model better defines the geohydrologic framework of the regional flow system and better delineates the supply and demand components that affect the inflows to and outflows from the regional ground-water flow system. Development of the model includes revisions to the previous ground-water flow model that upgraded the temporal and spatial discretization, added source-specific inflows and outflows, simulated additional flow features such as land subsidence and multi-aquifer wellbore flow, and extended the period of simulation through September 1999. The transient-state model was calibrated to historical surface-water and ground-water data for the period 197099 and to historical subsidence for the period 198399. The regional ground-water flow system consists of multiple aquifers that are grouped into upper- and lower-aquifer systems. Ground-water inflow occurs as natural recharge in the form of streamflow infiltration and areal infiltration of precipitation along stream channels, artificial recharge from infiltration of imported water at recharge ponds and along selected stream channels, and leakage along selected transmission pipelines. Ground-water outflow occurs as evapotranspiration, stream base flow, discharge through pumpage from wells, and subsurface flow to the San Francisco Bay. The geohydrologic framework of the regional ground-water flow system was represented as six model layers. The hydraulic properties were redefined on the basis of cell-based lithologic properties that were delineated in terms of aggregate thicknesses of coarse-grained, fine-grained, and mixed textural categories. The regional aquifer systems also are dissected by several laterally extensive faults that may form at least partial barriers to the lateral flow of ground water. The spatial extent of the ground-water flow model was extended and refined to cover the entire Santa Clara Valley, including the Evergreen subregion. The temporal discretization was refined and the period of simulation was extended to 197099. The model was upgraded to MODFLOW-2000 (MF2K) and was calibrated to fit historical ground-water levels, streamflow, and land subsidence for the period 197099. The revised model slightly overestimates measured water levels with an root-mean-square error of -7.34 feet. The streamflow generally shows a good match on gaged creeks and rivers for flows greater than 1.2 cubic feet per second. The revised model also fits the measured deformation at the borehole extensometer site located near San Jose within 16 to 27 percent and the extensometer site near Sunnyvale within 3 percent of the maximum measured seasonal deformation for the deepest extensometers. The total ground-water inflow and outflow of about 225,500 acre-feet per

Modeling solute transport in a heterogeneous unsaturated porous medium under dynamic boundary conditions on different spatial scales

NASA Astrophysics Data System (ADS)

Cremer, Clemens; Neuweiler, Insa; Bechtold, Michel

2013-04-01

Understanding transport of solutes/contaminants through unsaturated soil in the shallow subsurface is vital to assess groundwater quality, nutrient cycling or to plan remediation projects. Alternating precipitation and evaporation conditions causing upward and downward flux with differing flow paths, changes in saturation and related structural heterogeneity make the description of transport in the unsaturated zone near the soil-surface a complex problem. Preferential flow paths strongly depend, among other things, on the saturation of a medium. Recent studies (e.g. Bechtold et al., 2011) showed lateral flow and solute transport during evaporation conditions (upward flux) in vertically layered sand columns. Results revealed that during evaporation water and solute are redistributed laterally from coarse to fine media deeper in the soil, and towards zones of lowest hydraulic head near to the soil surface. These zones at the surface can be coarse or fine grained depending on saturation status and evaporation flux. However, if boundary conditions are reversed and precipitation is applied, the flow field is not reversed in the same manner, resulting in entirely different transport patterns for downward and upward flow. Therefore, considering net-flow rates alone is misleading when describing transport in the shallow unsaturated zone. In this contribution, we analyze transport of a solute in the shallow subsurface to assess effects resulting from the superposition of heterogeneous soil structures and dynamic flow conditions on various spatial scales. Two-dimensional numerical simulations of unsaturated flow and transport in heterogeneous porous media under changing boundary conditions are carried out using a finite-volume code coupled to a particle tracking algorithm to quantify solute transport and leaching rates. In order to validate numerical simulations, results are qualitatively compared to those of a physical experiment (Bechtold et al., 2011). Numerical simulations differ in lateral scale reaching from 0.2 m to 1.5 m, while the height of the domain is kept constant to 1.5m. Strong material heterogeneity is realized through vertical layers of coarse and fine sand. Both materials remain permanently under liquid-flow-dominated ('stage1') evaporation conditions. Spatial moments as well as the dilution index (Kitanidis, 1994) are used for quantification of transport behaviour. Results show that, while all simulations led to anomalous transport, infiltration-evaporation cycles lead to faster solute leaching rates than solely infiltration at the same net-infiltration rate in both homogeneous and heterogeneous media. Flow and transport-paths significantly differed between infiltration and evaporation, resulting in lateral water fluxes and hence lateral solute transport. Variation of the width of the model domain shows faster leaching rates for domains with small horizontal extent.

Post-injection Multiphase Flow Modeling and Risk Assessments for Subsurface CO2 Storage in Naturally Fractured Reservoirs

NASA Astrophysics Data System (ADS)

Jin, G.

2015-12-01

Subsurface storage of carbon dioxide in geological formations is widely regarded as a promising tool for reducing global atmospheric CO2 emissions. Successful geologic storage for sequestrated carbon dioxides must prove to be safe by means of risk assessments including post-injection analysis of injected CO2 plumes. Because fractured reservoirs exhibit a higher degree of heterogeneity, it is imperative to conduct such simulation studies in order to reliably predict the geometric evolution of plumes and risk assessment of post CO2injection. The research has addressed the pressure footprint of CO2 plumes through the development of new techniques which combine discrete fracture network and stochastic continuum modeling of multiphase flow in fractured geologic formations. A subsequent permeability tensor map in 3-D, derived from our preciously developed method, can accurately describe the heterogeneity of fracture reservoirs. A comprehensive workflow integrating the fracture permeability characterization and multiphase flow modeling has been developed to simulate the CO2plume migration and risk assessments. A simulated fractured reservoir model based on high-priority geological carbon sinks in central Alabama has been employed for preliminary study. Discrete fracture networks were generated with an NE-oriented regional fracture set and orthogonal NW-fractures. Fracture permeability characterization revealed high permeability heterogeneity with an order of magnitude of up to three. A multiphase flow model composed of supercritical CO2 and saline water was then applied to predict CO2 plume volume, geometry, pressure footprint, and containment during and post injection. Injection simulation reveals significant permeability anisotropy that favors development of northeast-elongate CO2 plumes, which are aligned with systematic fractures. The diffusive spreading front of the CO2 plume shows strong viscous fingering effects. Post-injection simulation indicates significant upward lateral spreading of CO2 resulting in accumulation of CO2 directly under the seal unit because of its buoyancy and strata-bound vertical fractures. Risk assessment shows that lateral movement of CO2 along interconnected fractures requires widespread seals with high integrity to confine the injected CO2.

General design method for 3-dimensional, potential flow fields. Part 2: Computer program DIN3D1 for simple, unbranched ducts

NASA Technical Reports Server (NTRS)

Stanitz, J. D.

1985-01-01

The general design method for three-dimensional, potential, incompressible or subsonic-compressible flow developed in part 1 of this report is applied to the design of simple, unbranched ducts. A computer program, DIN3D1, is developed and five numerical examples are presented: a nozzle, two elbows, an S-duct, and the preliminary design of a side inlet for turbomachines. The two major inputs to the program are the upstream boundary shape and the lateral velocity distribution on the duct wall. As a result of these inputs, boundary conditions are overprescribed and the problem is ill posed. However, it appears that there are degrees of compatibility between these two major inputs and that, for reasonably compatible inputs, satisfactory solutions can be obtained. By not prescribing the shape of the upstream boundary, the problem presumably becomes well posed, but it is not clear how to formulate a practical design method under this circumstance. Nor does it appear desirable, because the designer usually needs to retain control over the upstream (or downstream) boundary shape. The problem is further complicated by the fact that, unlike the two-dimensional case, and irrespective of the upstream boundary shape, some prescribed lateral velocity distributions do not have proper solutions.

Dual-Quantum-Dots-Labeled Lateral Flow Strip Rapidly Quantifies Procalcitonin and C-reactive Protein

NASA Astrophysics Data System (ADS)

Qi, XiaoPing; Huang, YunYe; Lin, ZhongShi; Xu, Liang; Yu, Hao

2016-03-01

In the article, a dual-quantum-dots-labeled (dual-QDs-labeled) lateral flow strip (LFS) method was developed for the simultaneous and rapid quantitative detection of procalcitonin (PCT) and C-reactive protein (CRP) in the blood. Two QD-antibody conjugates with different fluorescence emission spectra were produced and sprayed on the LFS to capture PCT and CRP in the blood. Furthermore, a double antibody sandwich method for PCT and, meanwhile, a competitive inhibition method for CRP were employed in the LFS. For PCT and CRP in serum assayed by the dual-QDs-labeled LFS, their detection sensitivities reached 0.1 and 1 ng/mL, respectively, and their linear quantitative detection ranges were from 0.3 to 200 ng/mL and from 50 to 250 μg/mL, respectively. There was little evidence that the PCT and CRP assays would be interfered with each other. The correlations for testing CRP and PCT in clinical samples were 99.75 and 97.02 %, respectively, between the dual-QDs-labeled LFS we developed and commercial methods. The rapid quantification of PCT and CRP on dual-QDs-labeled LFS is of great clinical value to distinguish inflammation, bacterial infection, or viral infection and to provide guidance for the use of antibiotics or other medicines.

Characterization of pollutant dispersion near elongated ...

EPA Pesticide Factsheets

This paper presents a wind tunnel study of the effects of elongated rectangular buildings on the dispersion of pollutants from nearby stacks. The study examines the influence of source location, building aspect ratio, and wind direction on pollutant dispersion with the goal of developing improved algorithms within dispersion models. The paper also examines the current AERMOD/PRIME modeling capabilities compared to wind tunnel observations. Differences in the amount of plume material entrained in the wake region downwind of a building for various source locations and source heights are illustrated with vertical and lateral concentration profiles. These profiles were parameterized using the Gaussian equation and show the influence of building/source configurations on those parameters. When the building is oriented at 45° to the approach flow, for example, the effective plume height descends more rapidly than it does for a perpendicular building, enhancing the resulting surface concentrations in the wake region. Buildings at angles to the wind cause a cross-wind shift in the location of the plume resulting from a lateral mean flow established in the building wake. These and other effects that are not well represented in many dispersion models are important considerations when developing improved algorithms to estimate the location and magnitude of concentrations downwind of elongated buildings. The National Exposure Research Laboratory (NERL) Computational Exposur

Characterization of pollutant dispersion near elongated buildings based on wind tunnel simulations

NASA Astrophysics Data System (ADS)

Perry, S. G.; Heist, D. K.; Brouwer, L. H.; Monbureau, E. M.; Brixey, L. A.

2016-10-01

This paper presents a wind tunnel study of the effects of elongated rectangular buildings on the dispersion of pollutants from nearby stacks. The study examines the influence of source location, building aspect ratio, and wind direction on pollutant dispersion with the goal of developing improved algorithms within dispersion models. The paper also examines the current AERMOD/PRIME modeling capabilities compared to wind tunnel observations. Differences in the amount of plume material entrained in the wake region downwind of a building for various source locations and source heights are illustrated with vertical and lateral concentration profiles. These profiles were parameterized using the Gaussian equation and show the influence of building/source configurations on those parameters. When the building is oriented at 45° to the approach flow, for example, the effective plume height descends more rapidly than it does for a perpendicular building, enhancing the resulting surface concentrations in the wake region. Buildings at angles to the wind cause a cross-wind shift in the location of the plume resulting from a lateral mean flow established in the building wake. These and other effects that are not well represented in many dispersion models are important considerations when developing improved algorithms to estimate the location and magnitude of concentrations downwind of elongated buildings.

Development of a lateral flow colloidal gold immunoassay strip for the rapid detection of enrofloxacin residues.

PubMed

Zhao, Yinli; Zhang, Gaiping; Liu, Qingtang; Teng, Man; Yang, Jifei; Wang, Jianhua

2008-12-24

A rapid immunochromatographic lateral flow test strip of competitive format has been developed using a gold-conjugated monoclonal antibody for the specific determination of enrofloxacin (ENR) residues in chicken muscles. For this purpose, a specific monoclonal antibody (mAb) for ENR was generated and characterized. The mAb showed negligible cross-reactivity with other related compounds. Using ENR standards prepared in chicken muscle extracts from 0 to 24.3 ng/mL (microg/kg), the method indicated that the detection limit of the test strip, as measured in a strip scanner, was as low as 0.138 microg/kg of ENR and the half-maximal inhibition concentration (IC(50)) was 0.935 microg/kg. For samples spiked at 10, 20, and 30 microg/kg, the recovery was between 85.3 and 96.1% and the coefficient of variation [CV (%)] was between 4.5 and 7.91%. Parallel analysis of muscle samples from chickens fed ENR showed good comparable results obtained from the test strip and LC-MS. Each test requires 5-10 min. The data indicate that the method has high sensitivity, specificity, and the advantages of simplicity and speed of performance. Therefore, the test strip provides a useful screening method for quantitative, semiquantitative, or qualitative detection of ENR residues in chicken muscles.

Recombinase polymerase amplification combined with lateral flow dipstick for equipment-free detection of Salmonella in shellfish.

PubMed

Gao, Weifang; Huang, Hailong; Zhu, Peng; Yan, Xiaojun; Fan, Jianzhong; Jiang, Jinpo; Xu, Jilin

2018-05-01

Salmonella is a major pathogen that causes acute foodborne outbreaks worldwide. Seafood, particularly shellfish, is a proven source of Salmonella spp. infection because many people prefer to eat it raw or lightly cooked. However, traditional identification methods are too time-consuming and complex to detect contamination of bacteria in the food chain in a timely manner, and few studies have aimed to identify Salmonella in shellfish early in the supply chain. We herein developed a method for rapid detection of Salmonella in shellfish based on the method of recombinase polymerase amplification (RPA) combined with lateral flow dipstick (LFD), which targets the invasion gene A (invA). The RPA-LFD was able to function at 30-45 °C, and at the temperature of 40 °C, it only took 8 min of amplification to reach the test threshold of amplicons. The established method had both a good specificity and a sensitivity of 100 fg DNA per reaction (20 µL). Regarding practical performance, RPA-LFD performed better than real-time PCR. Another advantage of RPA-LFD is that it was capable of being performed without expensive equipments. Thus, RPA-LFD has potential for further development as a detection kit for Salmonella in shellfish and other foods under field conditions.

Connectivity in modelling subsurface stormflow and tracer transport in a forested hillslope

NASA Astrophysics Data System (ADS)

Laine-Kaulio, Hanne; Koivusalo, Harri

2016-04-01

Preferential flow characterizes subsurface water movement in forested hillslopes. Connectivity of preferential flowpaths in soil, as well as connections between the preferential flowpaths and the soil matrix, control the flow patterns in hillslopes. We simulated subsurface stormflow and tracer transport within a forested hillslope section in Eastern Finland with a modifiable and detailed, physically-based 3-D dual-permeability model. The objective was to investigate the role of flowpath connectivity in capturing the observed migration velocity and concentration status of a tracer plume during the different stages of an irrigation experiment. Hypotheses to explain the observed transport behaviour were formulated based on observed spatial variations in the soil properties. The hypotheses were then tested by running corresponding model versions against spatial high-frequency data from the irrigation experiment. The 3-D distribution of preferential flowpaths, and the connections and disconnections between them, had the most crucial role in capturing the observed transport event with the model. Lateral by-pass flow in the preferential flow network and the transmissivity feedback phenomenon dominated the tracer transport. However, disconnections in lateral preferential flow restrained the transport, making the transport route devious instead of being directly lateral. These disconnections were caused by spots of cemented soil material. Stones had an opposite effect on the flow route formation compared to the cemented spots because preferential flowpaths were present on stone surfaces. Preferential flowpaths related to stones were linked with other types of preferential flowpaths in soil, facilitating the connectivity of preferential flowpaths within the entire hillslope. To take into account the discontinuity in lateral preferential flow and the tortuosity of the dominant flow routes in the model, an explicit representation of the 3-D distribution of saturated hydraulic conductivity in the preferential flow network was required. In addition, with-depth changing porosity values of both pore domains of soil, i.e., the preferential flowpaths and the soil matrix, as well as explicit descriptions of local water losses into the underlying bedrock, were found important for successful simulations. Other investigated model features, including complexity in the values of the rest of the model parameters and in the calculation routines used in describing the flow connections between the preferential flowpaths and the soil matrix, were not found beneficial for the model outcome.

Spatial distribution of early red lesions is a risk factor for development of vision-threatening diabetic retinopathy.

PubMed

Ometto, Giovanni; Assheton, Phil; Calivá, Francesco; Chudzik, Piotr; Al-Diri, Bashir; Hunter, Andrew; Bek, Toke

2017-12-01

Diabetic retinopathy is characterised by morphological lesions related to disturbances in retinal blood flow. It has previously been shown that the early development of retinal lesions temporal to the fovea may predict the development of treatment-requiring diabetic maculopathy. The aim of this study was to map accurately the area where lesions could predict progression to vision-threatening retinopathy. The predictive value of the location of the earliest red lesions representing haemorrhages and/or microaneurysms was studied by comparing their occurrence in a group of individuals later developing vision-threatening diabetic retinopathy with that in a group matched with respect to diabetes type, age, sex and age of onset of diabetes mellitus who did not develop vision-threatening diabetic retinopathy during a similar observation period. The probability of progression to vision-threatening diabetic retinopathy was higher in a circular area temporal to the fovea, and the occurrence of the first lesions in this area was predictive of the development of vision-threatening diabetic retinopathy. The calculated peak value showed that the risk of progression was 39.5% higher than the average. There was no significant difference in the early distribution of lesions in participants later developing diabetic maculopathy or proliferative diabetic retinopathy. The location of early red lesions in diabetic retinopathy is predictive of whether or not individuals will later develop vision-threatening diabetic retinopathy. This evidence should be incorporated into risk models used to recommend control intervals in screening programmes for diabetic retinopathy.

Effect of wing-tip dihedral on the longitudinal and lateral aerodynamic characteristics of a supersonic cruise configuration at subsonic speeds

NASA Technical Reports Server (NTRS)

Washburn, K. E.; Gloss, B. B.

1976-01-01

Force and moment data studies were conducted to determine the effect of wing-tip dihedral on the longitudinal and lateral aerodynamic characteristics of a supersonic cruise fighter configuration. Oil flow studies were also performed to investigate the model surface flow. Three models were tested: a flat (0 deg dihedral) wing tip, a dihedral, and an anhedral wing tip. The tests were conducted at the NASA Langley high-speed 7- by 10-foot wind tunnel.

Overview on Pendeo-Epitaxy of GaN-Based Heterostructures for Novel Devices Applications

DTIC Science & Technology

2006-11-01

pendeo-epitaxy uses the metal organic chemical vapor deposition (MOCVD) technique that commonly requires ammonia (NH3) and trimethyl gallium ( TMG ...lateral growth rate and the crystallography of the side walls of the pendeo-epitaxial GaN are the growth temperature, the ammonia to TMG flow rate...pressure of 100 Torr and V:III ratio of 2600. It is known that the ammonia to TMG (V:III) molar flow rate ratio plays a major role for the lateral to

Hydrogeochemical signatures of catchment evolution - the role of calcium and sulphate release in the constructed Hühnerwasser ("Chicken Creek") catchment

NASA Astrophysics Data System (ADS)

Pohle, Ina; Hu, Yuzhu; Schaaf, Wolfgang; Gerwin, Werner; Hinz, Christoph

2016-04-01

The constructed Hühnerwasser ("Chicken Creek") catchment is an ecohydrological system in an initial state of development. The catchment with an area of 6 ha was built up from quaternary sediments in the post-mining landscape of Lusatia in Eastern Germany and serves as a critical zone observatory for detecting ecosystem transition. The soil substrate is characterized as sands to loamy sands with low carbonate contents but significant amounts of gypsum in the sediments of the catchment. The catchment undergoes a strong transition from an abiotic system in the initial years to a system with growing influence of biota. Concerning the hydrology, a regime shift from surface runoff to groundwater flow dominated processes is significant. It is of interest, whether the catchment transition is also reflected by hydrogeochemical indicators. We assume gypsum dissolution as dominant process at the catchment scale. In order to investigate the hydrogeochemical evolution of the catchment we analysed electric conductivity, calcium and sulphate concentrations and pH-values of biweekly composite samples from 2007-2013 of the atmospheric deposition, of runoff and soil water. The two observation points in the flowing water represent surface runoff and groundwater discharge respectively. Soil water has been analysed at four soil pits in three depths. The monitoring data were provided by the Research Platform Chicken Creek (https://www.tu-cottbus.de/projekte/en/oekosysteme/startseite.html). From the macroscopic data analysis we found an exponential decay of the electric conductivity, calcium and sulphate concentrations in the flowing waters and some of the soil pits. In the flowing water, the decrease slope of the electric conductivity and the calcium and sulphate concentrations is almost identical. The calcium / sulphate molar ratio as an indicator of gypsum dissolution is almost equal to one up to 2010, afterwards more calcium than sulphate is released. The pH-values in the flowing and soil water are generally higher than in the atmospheric deposition, they do show variabilites but no trend behaviour. The time series analyses showed that the interannual variability of the hydrogeochemical properties is less pronounced in the first years of ecosystem development than in the later years. This leads to the conclusion, that in the first years, gypsum dissolution is the major source for calcium and sulphate in the soil and the flowing waters. The increasing interannual variability and changes in the calcium / sulphate ratio in the later years might be interpreted as hydrogeochemical response to the development of vegetation and acidification due to the development of the rhizosphere.

On the structure of cellular solutions in Rayleigh-Benard-Marangoni flows in small-aspect-ratio containers

NASA Technical Reports Server (NTRS)

Dijkstra, Henk A.

1992-01-01

Multiple steady flow patterns occur in surface-tension/buoyancy-driven convection in a liquid layer heated from below (Rayleigh-Benard-Marangoni flows). Techniques of numerical bifurcation theory are used to study the multiplicity and stability of two-dimensional steady flow patterns (rolls) in rectangular small-aspect-ratio containers as the aspect ratio is varied. For pure Marangoni flows at moderate Biot and Prandtl number, the transitions occurring when paths of codimension 1 singularities intersect determine to a large extent the multiplicity of stable patterns. These transitions also lead, for example, to Hopf bifurcations and stable periodic flows for a small range in aspect ratio. The influence of the type of lateral walls on the multiplicity of steady states is considered. 'No-slip' lateral walls lead to hysteresis effects and typically restrict the number of stable flow patterns (with respect to 'slippery' sidewalls) through the occurrence of saddle node bifurcations. In this way 'no-slip' sidewalls induce a selection of certain patterns, which typically have the largest Nusselt number, through secondary bifurcation.

Detection of target staphylococcal enterotoxin B antigen in orange juice and popular carbonated beverages using antibody-dependent antigen-capture assays.

PubMed

Principato, MaryAnn; Njoroge, Joyce M; Perlloni, Andrei; O' Donnell, Michael; Boyle, Thomas; Jones, Robert L

2010-10-01

There is a critical need for qualitative and quantitative methodologies that provide the rapid and accurate detection of food contaminants in complex food matrices. However, the sensitivity of the assay can be affected when antigen-capture is applied to certain foods or beverages that are extremely acidic. This study was undertaken to assess the effects of orange juice and popular carbonated soft drink upon the fidelity of antibody-based antigen-capture assays and to develop simple approaches that could rescue assay performance without the introduction of additional or extensive extraction procedures. We examined the effects of orange juice and a variety of popular carbonated soft drink beverages upon a quantitative Interleukin-2 (IL-2) enzyme-linked immunosorbent assay (ELISA) assay system and a lateral flow device (LFD) adapted for the detection of staphylococcal enterotoxin B (SEB) in foods. Alterations in the performance and sensitivity of the assay were directly attributable to the food matrix, and alterations in pH were especially critical. The results demonstrate that approaches such as an alteration of pH and the use of milk as a blocking agent, either singly or in combination, will partially rescue ELISA performance. The same approaches permit lateral flow to efficiently detect antigen. Practical Application: The authors present ways to rescue an ELISA assay compromised by acidity in beverages and show that either the alteration of pH, or the use of milk as a blocking agent are not always capable of restoring the assay to its intended efficiency. However, the same methods, when employed with lateral flow technology, are rapid and extremely successful.

Recombinase polymerase amplification (RPA) combined with lateral flow (LF) strip for detection of Toxoplasma gondii in the environment.

PubMed

Wu, Y D; Xu, M J; Wang, Q Q; Zhou, C X; Wang, M; Zhu, X Q; Zhou, D H

2017-08-30

Toxoplasma gondii infects all warm-blooded vertebrates, resulting in a great threat to human health and significant economic loss to the livestock industry. Ingestion of infectious oocysts of T. gondii from the environment is the major source of transmission. Detection of T. gondii oocysts by existing methods is laborious, time-consuming and expensive. The objective of the present study was to develop a recombinase polymerase amplification (RPA) method combined with a lateral flow (LF) strip for detection of T. gondii oocysts in the soil and water. The DNA of T. gondii oocysts was amplified by a pair of specific primers based on the T. gondii B1 gene over 15min at a constant temperature ranging from 30°C to 45°C using RPA. The amplification product was visualized by the lateral flow (LF) strip within 5min using the specific probe added to the RPA reaction system. The sensitivity of the established assay was 10 times higher than that of nested PCR with a lower detection limit of 0.1 oocyst per reaction, and there was no cross-reactivity with other closely related protozoan species. Fifty environmental samples were further assessed for the detection validity of the LF-RPA assay (B1-LF-RPA) and compared with nested PCR based on the B1 gene sequence. The B1-LF-RPA and nested PCR both showed that 5 out of the 50 environmental samples were positive. The B1-LF-RPA method was also proven to be sufficiently tolerant of existing inhibitors in the environment. In addition, the advantages of simple operation, speediness and cost-effectiveness make B1-LF-RPA a promising molecular detection tool for T. gondii. Copyright © 2017 Elsevier B.V. All rights reserved.

Lateral Variability of Lava flow Morphologies in the Deccan Traps Large Igneous Province (India)

NASA Astrophysics Data System (ADS)

Vanderkluysen, L.; Rader, E. L.; Self, S.; Clarke, A. B.; Sheth, H.; Moyer, D. K.

2016-12-01

In continental flood basalt provinces (CFBs), lava flow morphologies have traditionally been classified in two distinct groups recognizable in the field, expressing two different modes of lava flow emplacement mechanisms: (a) compound lava flow fields dominated by meter-sized pāhoehoe toes and lobes; and (b) inflated sheet lobes tens to hundreds of meters in width and meters to tens of meters in height. Temporal transitions between these two emplacement styles have been recognized in many mafic large igneous provinces worldwide and seem to be a fundamental feature of CFBs. However, lateral variations in these morphologies remain poorly studied and understood. In the Deccan CFB of India, two principal hypotheses have been proposed to account for possible lateral variations in lava flow facies: that smaller toes and lobes occur in distal regions of flow fields, representing breakouts at the edges of larger inflated lavas; or on the contrary that smaller toes and lobes represent proximal facies. We conducted a field study focusing on two of the Deccan's formations, the Khandala and the Poladpur, located in the middle and upper sections of the province's defined chemostratigraphy. We studied nine sections along a 600 km long E-W transect, with the easternmost sections representing the most distal outcrops, ≥ 500 km away from inferred vents. The Khandala Formation is traditionally described as a sequence of three thick inflated sheet lobes in the well-exposed sections of the western Deccan. However, in the central Deccan, we find the Khandala to be much thicker overall, with half of its thickness dominated by small, meter-sized toes and lobes. Inflated sheet lobes of the Khandala are thinner on average in the central Deccan than further to the east or west. We document this transition as occurring progressively in outcrops only 80 km apart. In the Poladpur, the average thickness of inflated sheet lobes increases in distal outcrops of the eastern Deccan. We interpret these results as an indication that smaller, meter-sized toes and lobes are indicative of proximal facies, whereas the thickest (> 10 m) inflated sheet lobes are the most likely to reach the far edges of the province. Analogue experiments are currently under way to test the relative importance of eruption parameters in the development of these morphologies.

Novel Monoclonal Antibody-Based Immunodiagnostic Assay for Rapid Detection of Deamidated Gluten Residues.

PubMed

Masiri, Jongkit; Benoit, Lora; Katepalli, Madhu; Meshgi, Mahzad; Cox, David; Nadala, Cesar; Sung, Shao-Lei; Samadpour, Mansour

2016-05-11

Gluten derived from wheat and related Triticeae can induce gluten sensitivity as well as celiac disease. Consequently, gluten content in foods labeled "gluten-free" is regulated. Determination of potential contamination in such foods is achieved using immunoassays based on monoclonal antibodies (mAbs) that recognize specific epitopes present in gluten. However, food-processing measures can affect epitope recognition. In particular, preparation of wheat protein isolate through deamidation of glutamine residues significantly limits the ability of commercial gluten testing kits in their ability to recognize gluten. Adding to this concern, evidence suggests that deamidated gluten imparts more pathogenic potential in celiac disease than native gluten. To address the heightened need for antibody-based tools that can recognize deamidated gluten, we have generated a novel mAb, 2B9, and subsequently developed it as a rapid lateral flow immunoassay. Herein, we report the ability of the 2B9-based lateral flow device (LFD) to detect gluten from wheat, barley, and rye and deamidated gluten down to 2 ppm in food as well as its performance in food testing.

Predictive techniques for river channel evolution and maintenance

USGS Publications Warehouse

Nelson, J.M.

1996-01-01

Predicting changes in alluvial channel morphology associated with anthropogenic and natural changes in flow and/or sediment supply is a critical part of the management of riverine systems. Over the past few years, advances in the understanding of the physics of sediment transport in conjunction with rapidly increasing capabilities in computational fluid dynamics have yielded now approaches to problems in river mechanics. Techniques appropriate for length scales ranging from reaches to bars and bedforms are described here. Examples of the use of these computational approaches are discussed for three cases: (1) the design of diversion scenarios that maintain channel morphology in steep cobble-bedded channels in Colorado, (2) determination of channel maintenance flows for the preservation of channel islands in the Snake River in Idaho, and (3) prediction of the temporal evolution of deposits in lateral separation zones for future assessment of the impacts of various dam release scenarios on lateral separation deposits in the Colorado River in Grand Canyon. With continued development of their scientific and technical components, the methodologies described here can provide powerful tools for the management of river environments in the future.

A rapid lateral-flow immunoassay for phytosanitary detection of Erwinia amylovora and on-site fire blight diagnosis.

PubMed

Braun-Kiewnick, A; Altenbach, D; Oberhänsli, T; Bitterlin, W; Duffy, B

2011-10-01

Fire blight is an invasive disease caused by Erwinia amylovora that threatens pome fruit production globally. Effective implementation of phytosanitary control measures depends upon rapid, reliable pathogen detection and disease diagnosis. We developed a lateral-flow immunoassay specific for E. amylovora with a detection limit of log 5.7 CFU/ml, typical of pathogen concentrations in symptomatic plant material. The simple assay had comparable sensitivity to standard culture plating, serum agglutination and nested PCR when validated for application in a phytosanitary laboratory as a confirmatory test of cultured isolates and for first-line diagnosis of phytosanitary samples that represent the full range of commercial, ornamental and forestry host species. On-site validation in ring-trials with local plant inspectors demonstrated robust and reliable detection (compared to subsequent plating and PCR analysis). The simplicity, inspector acceptance and facilitation of expedited diagnosis (from 2 days for laboratory submitted samples to 15 min with the immunoassay), offers a valuable tool for improved phytosanitary control of fire blight. Copyright © 2011 Elsevier B.V. All rights reserved.

Ultrasensitive Immunochromatographic Strip for Fast Screening of 27 Sulfonamides in Honey and Pork Liver Samples Based on a Monoclonal Antibody.

PubMed

Chen, Yanni; Guo, Lingling; Liu, Liqiang; Song, Shanshan; Kuang, Hua; Xu, Chuanlai

2017-09-20

Group-specific monoclonal antibodies (Mabs) with selectivity for 27 sulfonamides were developed based on new combinations of immunogen and coating antigen. The Mab was able to recognize 27 sulfonamides with 50% inhibition concentration (IC 50 ) values ranging from 0.15 to 15.38 μg/L. In particular, the IC 50 values for five sulfonamides (sulfamethazine, sulfaquinoxaline, sulfamonomethoxine, sulfadimethoxine, and sulfamethoxazole) were 0.51, 0.15, 0.56, 0.54, and 2.14 μg/L, respectively. On the basis of the Mab, an immunochromatographic lateral flow strip test was established for rapid screening of sulfonamides in honey samples. The visual limit of detection of the strip test for most sulfonamides in spiked honey samples was below 10 μg/kg, satisfying the requirements of authorities. Positive honey and pork liver samples, which had been confirmed by high-performance liquid chromatography/mass spectrometry, were used to validate the reliability of the proposed strip test. The immunochromatographic lateral flow strip test provides a rapid and convenient method for fast screening of sulfonamides in honey samples.

Salix response to different flow regimes in controlled experiments: first results

NASA Astrophysics Data System (ADS)

Gorla, Lorenzo; Signarbieux, Constant; Buttler, Alexandre; Perona, Paolo

2013-04-01

Dams and water management for hydropower production, agriculture and other human activities alter the natural flow regime of rivers. The new river hydrograph components depend on the type of impoundment and the policy of regulation but such a different flow regime will likely affect the riparian environment. The main challenge in order to define sustainable flow releases is to quantify hydrological effects in terms of geomorphology and ecosystem response. A considerable lack of knowledge still affects the link hydrology-ecology and inadequate flow rules (e.g., minimal or residual flows) are consequently still widespread: further research in this direction is urgently required. We present an experiment, which aims to investigate the effects of different water stage regimes on riparian vegetation (salix Viminalis cuttings) development in a temperate region (Switzerland). This work describes the installation setup, together with the first results concerning the first of the two scheduled seasons of campaign. Sixty Salix cuttings were planted in non-cohesive sandy-gravel sediment within 1 meter tall plastic pots installed outside in the EPFL campus. After grouping them in three batteries, the water level within them has been varying following three river regimes simulated by adjusting the water level within the pots by means of an automatic hydraulic system. The three water level regimes reproduce a natural flow regime, a minimum residual flow policy, which only conserves peaks during flooding conditions, and an artificial regime conserving only low frequencies (e.g., seasonality) of the natural dynamic. The natural flow regime of the first battery has been applied for two months to the entire system; the three regimes above said started in June 2012. This triggered a plant response transitory regime, which we monitored by measuring plant growth, soil and atmospheric variables. Particularly, measures concern with branches development leaves photosynthesis and fluorescence, together with pictures of each plant. Sap flow was measured for thirty cuttings using a time resolution of thirty minutes, whereas psychrometers measuring the water potential were sampling data every fifteen minutes. Soil moisture and meteo data have also been collected as essential drivers of plant response: these data as well as sap flow measurements can be later compared to a similar field installation along Thur River (Switzerland). After the first season of measurement, in 2012, part of the cuttings have been carefully removed and further analyzed as far as the below ground biomass is concerned. Strong differences in terms of stress and growth performances were observed in correspondence of the transitional phase, following the alterations of the natural flow regime. A later adjustment in the roots distribution allowed survivors to re-sprout and to withstand new conditions.

Experimental Investigation of the Flow Structure over a Delta Wing Via Flow Visualization Methods.

PubMed

Shen, Lu; Chen, Zong-Nan; Wen, Chihyung

2018-04-23

It is well known that the flow field over a delta wing is dominated by a pair of counter rotating leading edge vortices (LEV). However, their mechanism is not well understood. The flow visualization technique is a promising non-intrusive method to illustrate the complex flow field spatially and temporally. A basic flow visualization setup consists of a high-powered laser and optic lenses to generate the laser sheet, a camera, a tracer particle generator, and a data processor. The wind tunnel setup, the specifications of devices involved, and the corresponding parameter settings are dependent on the flow features to be obtained. Normal smoke wire flow visualization uses a smoke wire to demonstrate the flow streaklines. However, the performance of this method is limited by poor spatial resolution when it is conducted in a complex flow field. Therefore, an improved smoke flow visualization technique has been developed. This technique illustrates the large-scale global LEV flow field and the small-scale shear layer flow structure at the same time, providing a valuable reference for later detailed particle image velocimetry (PIV) measurement. In this paper, the application of the improved smoke flow visualization and PIV measurement to study the unsteady flow phenomena over a delta wing is demonstrated. The procedure and cautions for conducting the experiment are listed, including wind tunnel setup, data acquisition, and data processing. The representative results show that these two flow visualization methods are effective techniques for investigating the three-dimensional flow field qualitatively and quantitatively.

Simulated ground-water flow and sources of water in the Killbuck Creek Valley near Wooster, Wayne County, Ohio

USGS Publications Warehouse

Breen, K.J.; Kontis, A.L.; Rowe, G.L.; Haefner, R.J.

1995-01-01

The stratified-drift aquifer in the 3,000-ft (feet)-wide and 100-ft-deep buried valley of Killbuck Creek near Wooster in northeastern Ohio was studied. The stratified drift with adjacent sandstone and shale bedrock produce a system of ground-water flow representative of the western part of the glaciated north-eastern United States. The stratified-drift aquifer is an excellent source of water for municipal and industrial wells. The aquifer is recharged locally by water from precipitation on the valley floor and uplands, by infiltration from streams, and by lateral flow to the valley from the uplands. As a result, the aquifer is vulnerable to surface or subsurface spills of contaminants in the valley or the adjacent uplands. Quality of water in the stratified drift is affected by influx of water from bedrock lateral to or beneath the valley. This influx is controlled, in part, by the pumping stress placed on the stratified-drift aquifer. Hydrogeologic and aqueous-geochemical data were analyzed to establish the framework necessary for stead-state and transient simulations of ground-water flow in stratified drift and bedrock with a three-layer ground-water-flow model. A new model routine, the Variable-Recharge procedure, was developed to simulate areal recharge and the contribution of the uplands to the drift system. This procedure allows for water applied to land surface to infiltrate or to be rejected. Rejected recharge and ground water discharged when the water table is at land surface form surface runoff-this excess upland water can be redirected as runoff to other parts of the model. Infiltration of streamwater, areal recharge to uplands and valley, and lateral subsurface flow from the uplands to the valley are sources of water to the stratufued0druft aquifer. Water is removed from the stratified-drift aquifer at Wooster primarily by production wells pumping at a rate of approximately 8.5 ft3/s (cubic feet per second). The ground-water budget resulting from two types of simulations of ground-water flow in this study indicates the primary sources of water to the wells are recharge at or near land surface and lateral subsurface flow from the shale and sandstone bedrock. Components of recharge at land surface include induced infiltration from streams, precipitation on the valley floor, and infiltration of unchanneled upland runoff that reaches the valley floor. The steady-state simulation was designed to represent conditions during the fall of 1984. The transient simulation was designed to represent an 11-day snowmelt event, 23 February to 5 March 1985, that caused water levels to rise significantly throughout the valley. Areal recharge to the valley and flow from the uplands to the valley were determined through the Variable-Recharge procedure. The total steady-state recharge to the valley was 12.5 ft3/s. Upland sources, areal valley recharge, and induced infiltration from Killnuck Creek accounted for 63, 23, and 8 percent, respectively, of the valley recharge. An analysis of the simulated vertical flow to the buried stratified drift through surficial slit, clay, and fine sand indicates that about 75 percent of the total recharge to the buried deposits is the sum of areally extensive, relatively small flows less than about 0.01 ft? /s per model node), whereas about 25 percent of the recharge results from a really restricted, relatively large flows (greater than about 0.01 ft? /s per model node). The large-magnitude flows are located primarily beneath Clear and Little Killbuck Creeks where seepage provides abundant recharge and the surficial sediments grade into coarser alluvial-fan deposits. Chemical and isotopic studies of ground water and streamwater combined with measurements of stream infiltration provide independent support for the conclusions derived from computer simulation of ground-water flow. In addition, the chemical and isotopic studies helped quantity the rate and pathways of infiltrating water from

Topographically Driven Lateral Water Fluxes and Their Influence on Carbon Assimilation of a Black Spruce Ecosystem.

NASA Astrophysics Data System (ADS)

Govind, A.; Chen, J. M.; Margolis, H.; Bernier, P. Y.

2006-12-01

Current estimates of ecophysiological indicators overlook the effects of topographically-driven lateral flow of soil water. We hypothesize that topographically driven lateral water flows over the landscape have significant influence on the terrestrial carbon cycle. To this end, we simulated the hydrological controls on carbon cycle processes in a black spruce forest in central Quebec, Canada, using the Boreal Ecosystem Productivity Simulator (BEPS) at a daily time step. We accounted for lateral surface and subsurface flows in BEPS by incorporating a distributed, process-oriented hydrological procedure. The results show that modeled dynamics of ecophysiological processes such as evapotranspiration (ET) and photosynthesis (GPP) are consistent with the spatial variation of land cover, topography, soil texture, and leaf area index. Simulated ET and GPP averaged within the footprint of an eddy covariance tower in the watershed agree well with flux measurements with R2=0.77 and 0.83 for ET and GPP, respectively. For ET simulation, much of the remaining discrepancies are found in the winter when the model underestimates snow sublimation. For GPP, there is an underestimation in the fall coinciding with a mid growing season drought, showing the high sensitivity of the model to the soil water status. The key processes controlling primary production were hydraulic limitations for water transfer from soil, roots, stems and leaves through stomatal conductance. Therefore, a further understanding of soil water dynamics is warranted. Comparison with the soil water content of the footprint- averaged unsaturated zone showed that the model captured the annual trend. We also simulated the variations in the water table as well as the mid growing season drought, with a reasonable accuracy(R2=0.68). The foot print average water budget reveals that the annual precipitation of 835mm is partitioned into 282mm of ET, 541 mm of subsurface runoff, and 6 mm of storage change. To test the influence of topographically driven lateral water flow on the carbon cycle, we made three hydrological modeling scenarios viz. 1) explicit hydrological simulation including lateral water routing, 2) bucket model with implicit runoff calculations and 3) a control run, where the lateral water flow was turned off in the model. Bucket model overestimated GPP as much as 25% as opposed to explicit simulations because there was no topographical constrain on runoff. Flat areas dominated with mineral soils shows the highest overestimation because of an increase in stomatal conductance. Control simulation, on the other hand, underestimated GPP as much as 15% as opposed to explicit routing because of rapid soil saturation, which decreases stomatal conductance. These results suggest that lateral water flow does play a significant role in the terrestrial carbon cycle and should be accounted for in ecological models. For details please see http://ajit.govind.googlepages.com/agu2006

Modeling growth kinetics of thin films made by atomic layer deposition in lateral high-aspect-ratio structures

NASA Astrophysics Data System (ADS)

Ylilammi, Markku; Ylivaara, Oili M. E.; Puurunen, Riikka L.

2018-05-01

The conformality of thin films grown by atomic layer deposition (ALD) is studied using all-silicon test structures with long narrow lateral channels. A diffusion model, developed in this work, is used for studying the propagation of ALD growth in narrow channels. The diffusion model takes into account the gas transportation at low pressures, the dynamic Langmuir adsorption model for the film growth and the effect of channel narrowing due to film growth. The film growth is calculated by solving the diffusion equation with surface reactions. An efficient analytic approximate solution of the diffusion equation is developed for fitting the model to the measured thickness profile. The fitting gives the equilibrium constant of adsorption and the sticking coefficient. This model and Gordon's plug flow model are compared. The simulations predict the experimental measurement results quite well for Al2O3 and TiO2 ALD processes.

Nonplanar wing load-line and slender wing theory

NASA Technical Reports Server (NTRS)

Deyoung, J.

1977-01-01

Nonplanar load line, slender wing, elliptic wing, and infinite aspect ratio limit loading theories are developed. These are quasi two dimensional theories but satisfy wing boundary conditions at all points along the nonplanar spanwise extent of the wing. These methods are applicable for generalized configurations such as the laterally nonplanar wing, multiple nonplanar wings, or wing with multiple winglets of arbitrary shape. Two dimensional theory infers simplicity which is practical when analyzing complicated configurations. The lateral spanwise distribution of angle of attack can be that due to winglet or control surface deflection, wing twist, or induced angles due to multiwings, multiwinglets, ground, walls, jet or fuselage. In quasi two dimensional theory the induced angles due to these extra conditions are likewise determined for two dimensional flow. Equations are developed for the normal to surface induced velocity due to a nonplanar trailing vorticity distribution. Application examples are made using these methods.

Experimental study of the laminar-turbulent transition of a concave wall in a parallel flow

NASA Technical Reports Server (NTRS)

Bippes, H.

1978-01-01

The instability of the laminar boundary layer flow along a concave wall was studied. Observations of these three-dimensional boundary layer phenomena were made using the hydrogen-bubble visualization technique. With the application of stereo-photogrammetric methods in the air-water system it was possible to investigate the flow processes qualitatively and quantitatively. In the case of a concave wall of sufficient curvature, a primary instability occurs first in the form of Goertler vortices with wave lengths depending upon the boundary layer thickness and the wall curvature. At the onset the amplification rate is in agreement with the linear theory. Later, during the non-linear amplification stage, periodic spanwise vorticity concentrations develop in the low velocity region between the longitudinal vortices. Then a meandering motion of the longitudinal vortex streets subsequently ensues, leading to turbulence.

Influence of vortical flow structures on the glottal jet location in the supraglottal region.

PubMed

Kniesburges, Stefan; Hesselmann, Christina; Becker, Stefan; Schlücker, Eberhard; Döllinger, Michael

2013-09-01

Within the fully coupled multiphysics phonation process, the fluid flow plays an important role for sound production. This study addresses phenomena in the flow downstream of synthetic self-oscillating vocal folds. An experimental setup consisting of devices for producing and conditioning the flow including the main test channel was applied. The supraglottal channel was designed to prevent an acoustic coupling to the vocal folds. Hence, the oscillations were aerodynamically driven. The cross-section of the supraglottal channel was systematically varied by increasing the distance between the lateral channel walls. The vocal folds consisted of silicone rubber of homogenous material distribution generating self-sustained oscillations. The airflow was visualized in the immediate supraglottal region using a laser-sheet technique and a digital high-speed camera. Furthermore, the flow was studied by measuring the static pressure distributions on both lateral supraglottal channel walls. The results clearly showed different flow characteristics depending on the supraglottal configuration. In all cases with supraglottal channel, the jet was located asymmetrical and bent in medial-lateral direction. Furthermore, the side to which the jet was deflected changed in between the consecutive cycles showing a bifurcational behavior. Previously, this phenomenon was explained by the Coanda effect. However, the present data suggest that the deflection of the jet was mainly caused by large air vortices in the supraglottal channel produced by the flow field of previous oscillations. In contrast, for the case without supraglottal channel, the air jet was found totally symmetrical stabilized by the constant pressure in the ambient region. The emitted sound signal showed additional subharmonic tonal peaks for the asymmetric flow cases, which are characteristics for diplophonia. Copyright © 2013 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

Interactions of non-spherical particles in simple flows

NASA Astrophysics Data System (ADS)

Niazi, Mehdi; Brandt, Luca; Costa, Pedro; Breugem, Wim-Paul

2015-11-01

The behavior of particles in a flow affects the global transport and rheological properties of the mixture. In recent years much effort has been therefore devoted to the development of an efficient method for the direct numerical simulation (DNS) of the motion of spherical rigid particles immersed in an incompressible fluid. However, the literature on non-spherical particle suspensions is quite scarce despite the fact that these are more frequent. We develop a numerical algorithm to simulate finite-size spheroid particles in shear flows to gain new understanding of the flow of particle suspensions. In particular, we wish to understand the role of inertia and its effect on the flow behavior. For this purpose, DNS simulations with a direct-forcing immersed boundary method are used, with collision and lubrication models for particle-particle and particle-wall interactions. We will discuss pair interactions, relative motion and rotation, of two sedimenting spheroids and show that the interaction time increases significantly for non-spherical particles. More interestingly, we show that the particles are attracted to each other from larger lateral displacements. This has important implications for collision kernels. This work was supported by the European Research Council Grant No. ERC-2013-CoG-616186, TRITOS, and by the Swedish Research Council (VR).

A novel multi-walled carbon nanotube-based antibody conjugate for quantitative and semi-quantitative lateral flow assays.

PubMed

Sun, Wenjuan; Hu, Xiaolong; Liu, Jia; Zhang, Yurong; Lu, Jianzhong; Zeng, Libo

2017-10-01

In this study, the multi-walled carbon nanotubes (MWCNTs) were applied in lateral flow strips (LFS) for semi-quantitative and quantitative assays. Firstly, the solubility of MWCNTs was improved using various surfactants to enhance their biocompatibility for practical application. The dispersed MWCNTs were conjugated with the methamphetamine (MET) antibody in a non-covalent manner and then manufactured into the LFS for the quantitative detection of MET. The MWCNTs-based lateral flow assay (MWCNTs-LFA) exhibited an excellent linear relationship between the values of test line and MET when its concentration ranges from 62.5 to 1500 ng/mL. The sensitivity of the LFS was evaluated by conjugating MWCNTs with HCG antibody and the MWCNTs conjugated method is 10 times more sensitive than the one conjugated with classical colloidal gold nanoparticles. Taken together, our data demonstrate that MWCNTs-LFA is a more sensitive and reliable assay for semi-quantitative and quantitative detection which can be used in forensic analysis.

Soil pipe flow tracer experiments: 1. Connectivity and transport characteristics

USDA-ARS?s Scientific Manuscript database

Much debate has occurred in catchment hydrology regarding the connectivity of flow paths from upslope areas to catchment outlets. This study was conducted in two catchments, one with three upper branches, in a loess soil with a fragipan that fosters lateral flow and exhibits an extensive distributio...

Increasing Sensitivity In Continuous-Flow Electrophoresis

NASA Technical Reports Server (NTRS)

Sharnez, Rizwan; Sammons, David W.

1994-01-01

Sensitivity of continuous-flow electrophoresis (CFE) chamber increased by introducing lateral gradients in concentration of buffer solution and thickness of chamber. Such gradients, with resulting enhanced separation, achieved in CFE chamber with wedge-shaped cross section and collateral flow. Enables improved separations of homogeneous components of mixtures of variety of biologically important substances.

Blood flow patterns underlie developmental heart defects

PubMed Central

Midgett, Madeline; Thornburg, Kent

2017-01-01

Although cardiac malformations at birth are typically associated with genetic anomalies, blood flow dynamics also play a crucial role in heart formation. However, the relationship between blood flow patterns in the early embryo and later cardiovascular malformation has not been determined. We used the chicken embryo model to quantify the extent to which anomalous blood flow patterns predict cardiac defects that resemble those in humans and found that restricting either the inflow to the heart or the outflow led to reproducible abnormalities with a dose-response type relationship between blood flow stimuli and the expression of cardiac phenotypes. Constricting the outflow tract by 10–35% led predominantly to ventricular septal defects, whereas constricting by 35–60% most often led to double outlet right ventricle. Ligation of the vitelline vein caused mostly pharyngeal arch artery malformations. We show that both cardiac inflow reduction and graded outflow constriction strongly influence the development of specific and persistent abnormal cardiac structure and function. Moreover, the hemodynamic-associated cardiac defects recapitulate those caused by genetic disorders. Thus our data demonstrate the importance of investigating embryonic blood flow conditions to understand the root causes of congenital heart disease as a prerequisite to future prevention and treatment. NEW & NOTEWORTHY Congenital heart defects result from genetic anomalies, teratogen exposure, and altered blood flow during embryonic development. We show here a novel “dose-response” type relationship between the level of blood flow alteration and manifestation of specific cardiac phenotypes. We speculate that abnormal blood flow may frequently underlie congenital heart defects. PMID:28062416

Transcriptional regulation of PIN genes by FOUR LIPS and MYB88 during Arabidopsis root gravitropism.

PubMed

Wang, Hong-Zhe; Yang, Ke-Zhen; Zou, Jun-Jie; Zhu, Ling-Ling; Xie, Zi Dian; Morita, Miyo Terao; Tasaka, Masao; Friml, Jiří; Grotewold, Erich; Beeckman, Tom; Vanneste, Steffen; Sack, Fred; Le, Jie

2015-11-18

PIN proteins are auxin export carriers that direct intercellular auxin flow and in turn regulate many aspects of plant growth and development including responses to environmental changes. The Arabidopsis R2R3-MYB transcription factor FOUR LIPS (FLP) and its paralogue MYB88 regulate terminal divisions during stomatal development, as well as female reproductive development and stress responses. Here we show that FLP and MYB88 act redundantly but differentially in regulating the transcription of PIN3 and PIN7 in gravity-sensing cells of primary and lateral roots. On the one hand, FLP is involved in responses to gravity stimulation in primary roots, whereas on the other, FLP and MYB88 function complementarily in establishing the gravitropic set-point angles of lateral roots. Our results support a model in which FLP and MYB88 expression specifically determines the temporal-spatial patterns of PIN3 and PIN7 transcription that are closely associated with their preferential functions during root responses to gravity.

Ultrafast Ultrasound Imaging of Ocular Anatomy and Blood Flow

PubMed Central

Urs, Raksha; Ketterling, Jeffrey A.; Silverman, Ronald H.

2016-01-01

Purpose Ophthalmic ultrasound imaging is currently performed with mechanically scanned single-element probes. These probes have limited capabilities overall and lack the ability to image blood flow. Linear-array systems are able to detect blood flow, but these systems exceed ophthalmic acoustic intensity safety guidelines. Our aim was to implement and evaluate a new linear-array–based technology, compound coherent plane-wave ultrasound, which offers ultrafast imaging and depiction of blood flow at safe acoustic intensity levels. Methods We compared acoustic intensity generated by a 128-element, 18-MHz linear array operated in conventionally focused and plane-wave modes and characterized signal-to-noise ratio (SNR) and lateral resolution. We developed plane-wave B-mode, real-time color-flow, and high-resolution depiction of slow flow in postprocessed data collected continuously at a rate of 20,000 frames/s. We acquired in vivo images of the posterior pole of the eye by compounding plane-wave images acquired over ±10° and produced images depicting orbital and choroidal blood flow. Results With the array operated conventionally, Doppler modes exceeded Food and Drug Administration safety guidelines, but plane-wave modalities were well within guidelines. Plane-wave data allowed generation of high-quality compound B-mode images, with SNR increasing with the number of compounded frames. Real-time color-flow Doppler readily visualized orbital blood flow. Postprocessing of continuously acquired data blocks of 1.6-second duration allowed high-resolution depiction of orbital and choroidal flow over the cardiac cycle. Conclusions Newly developed high-frequency linear arrays in combination with plane-wave techniques present opportunities for the evaluation of ocular anatomy and blood flow, as well as visualization and analysis of other transient phenomena such as vessel wall motion over the cardiac cycle and saccade-induced vitreous motion. PMID:27428169

Geochemical variations during development of the 5.46 Ma Broadwell Mesa basaltic volcanic field, California

USGS Publications Warehouse

Buesch, David C.

2017-01-01

The 5.46±0.04 Ma Broadwell Mesa basalt and associated basaltic volcanic field in the western Bristol Mountains, California, formed a ~6 km2 volcanic flow field with architecture including numerous lava flows, a ~1.1 km2 lava lake, and a ~0.17 km2 cinder cone. The local number of lava flows varies from one along the margins of the field to as many as 18 that are stacked vertically, onlapped by younger flows, or are laterally adjacent to each other. Geochemical plots of 40 hand samples indicate that all lava flows are basalt and that the field is slightly compositionally zoned. Typically, there is a progressive change in composition in sequentially overlying lava flows, although in some flow sequences, the overlying flow has an “across trend” step in composition, and a few have an “against trend” step in composition. The progressive compositional change indicates that the magmatic composition evolved during the history of the field, and the “across trend” and minor “against trend” steps probably represent periods of crystal fractionation or reinjection of magma during hiatuses in eruptions. The lack of clastic sedimentary rocks or even aeolianite interstratified with the lava flows probably indicates that the Broadwell Mesa volcanic field was short-lived.

DOE Office of Scientific and Technical Information (OSTI.GOV)

McKee, E.H.

Ground water flow through the region south and west of Frenchman Flat, in the Ash Meadows subbasin of the Death Valley ground water flow system, is controlled mostly by the distribution of permeable and impermeable rocks. Geologic structures such as faults are instrumental in arranging the distribution of the aquifer and aquitard rock units. Most permeability is in fractures caused by faulting in carbonate rocks. Large faults are more likely to reach the potentiometric surface about 325 meters below the ground surface and are more likely to effect the flow path than small faults. Thus field work concentrated on identifyingmore » large faults, especially where they cut carbonate rocks. Small faults, however, may develop as much permeability as large faults. Faults that are penetrative and are part of an anastomosing fault zone are particularly important. The overall pattern of faults and joints at the ground surface in the Spotted and Specter Ranges is an indication of the fracture system at the depth of the water table. Most of the faults in these ranges are west-southwest-striking, high-angle faults, 100 to 3500 meters long, with 10 to 300 /meters of displacement. Many of them, such as those in the Spotted Range and Rock Valley are left-lateral strike-slip faults that are conjugate to the NW-striking right-lateral faults of the Las Vegas Valley shear zone. These faults control the ground water flow path, which runs west-southwest beneath the Spotted Range, Mercury Valley and the Specter Range. The Specter Range thrust is a significant geologic structure with respect to ground water flow. This regional thrust fault emplaces siliceous clastic strata into the north central and western parts of the Specter Range.« less

Comparison of Two Conceptually Different Physically-based Hydrological Models - Looking Beyond Streamflows

NASA Astrophysics Data System (ADS)

Rousseau, A. N.; Álvarez; Yu, X.; Savary, S.; Duffy, C.

2015-12-01

Most physically-based hydrological models simulate to various extents the relevant watershed processes occurring at different spatiotemporal scales. These models use different physical domain representations (e.g., hydrological response units, discretized control volumes) and numerical solution techniques (e.g., finite difference method, finite element method) as well as a variety of approximations for representing the physical processes. Despite the fact that several models have been developed so far, very few inter-comparison studies have been conducted to check beyond streamflows whether different modeling approaches could simulate in a similar fashion the other processes at the watershed scale. In this study, PIHM (Qu and Duffy, 2007), a fully coupled, distributed model, and HYDROTEL (Fortin et al., 2001; Turcotte et al., 2003, 2007), a pseudo-coupled, semi-distributed model, were compared to check whether the models could corroborate observed streamflows while equally representing other processes as well such as evapotranspiration, snow accumulation/melt or infiltration, etc. For this study, the Young Womans Creek watershed, PA, was used to compare: streamflows (channel routing), actual evapotranspiration, snow water equivalent (snow accumulation and melt), infiltration, recharge, shallow water depth above the soil surface (surface flow), lateral flow into the river (surface and subsurface flow) and height of the saturated soil column (subsurface flow). Despite a lack of observed data for contrasting most of the simulated processes, it can be said that the two models can be used as simulation tools for streamflows, actual evapotranspiration, infiltration, lateral flows into the river, and height of the saturated soil column. However, each process presents particular differences as a result of the physical parameters and the modeling approaches used by each model. Potentially, these differences should be object of further analyses to definitively confirm or reject modeling hypotheses.

Macro-/Nano- Materials Based Ultrasensitive Lateral Flow Nucleic Acid Biosensors

NASA Astrophysics Data System (ADS)

Takalkar, Sunitha

Ultrasensitive detection of nucleic acids plays a very important role in the field of molecular diagnosis for the detection of various diseases. Lateral flow biosensors (LFB) are convenient, easy-to-use, patient friendly forms of detection methods offering rapid and convenient clinical testing in close proximity to the patients thus drawing a lot of attention in different areas of research over the years. In comparison with the traditional immunoassays, the nucleic acid based lateral flow biosensors (NABLFB) has several advantages in terms of stability and interference capabilities. NABLFB utilizes nucleic acid probes as the bio-recognition element. The target analyte typically is the oligonucleotide like the DNA, mRNA, miRNA which are among the nucleic acid secretions by the tumor cells when it comes to detection of cancer. Traditionally gold nanoparticles (GNPs) have been used as labels for conjugating with the detection probes for the qualitative and semi quantitative analysis, the application of GNP-based LFB is limited by its low sensitivity. This dissertation describes the use of different nanomaterials and advanced detection technologies to enhance the sensitivities of the LFB based methods. Silica Nanorods decorated with GNP were synthesized and employed as labels for ultrasensitive detection of miRNA on the LFB. Owing to the biocompatibility and convenience in surface modification of SiNRs, they acted as good carriers to load numerous GNPs. The sensitivity of the GNP-SiNR-based LFSB was enhanced six times compared to the previous GNP-based LFSB. A fluorescent carbon nanoparticle (FCN) was first used as a tag to develop a lateral flow nucleic acid biosensor for ultrasensitive and quantitative detection of nucleic acid samples. Under optimal conditions, the FCN-based LFNAB was capable of detecting minimum 0.4 fM target DNA without complex operations and additional signal amplification. The carbon nanotube was used as a label and carrier of numerous enzyme and DNA molecules simultaneously thus resulting in the enormous amplification of the colorimetric signal. This CNT-enzyme label thus aided the ultra-sensitive detection of pancreatic cancer (PC) biomarker miRNA 210 and PC biomarker panel (miRNA 16, miRNA 21 and miRNA 196a). All these LFBs were also applied in the field of real sample detection.

Evaluation of detection methods for screening meat and poultry products for the presence of foodborne pathogens.

PubMed

Bohaychuk, Valerie M; Gensler, Gary E; King, Robin K; Wu, John T; McMullen, Lynn M

2005-12-01

Rapid and molecular technologies such as enzyme-linked immunosorbent assay (ELISA), PCR, and lateral flow immunoprecipitation can reduce the time and labor involved in screening food products for the presence of pathogens. These technologies were compared with conventional culture methodology for the detection of Salmonella, Campylobacter, Listeria, and Escherichia coli O157:H7 inoculated in raw and processed meat and poultry products. Recommended protocols were modified so that the same enrichment broths used in the culture methods were also used in the ELISA, PCR, and lateral flow immunoprecipitation assays. The percent agreement between the rapid technologies and culture methods ranged from 80 to 100% depending on the pathogen detected and the method used. ELISA, PCR, and lateral flow immunoprecipitation all performed well, with no statistical difference, compared with the culture method for the detection of E. coli O157:H7. ELISA performed better for the detection of Salmonella, with sensitivity and specificity rates of 100%. PCR performed better for the detection of Campylobacter jejuni, with 100% agreement to the culture method. PCR was highly sensitive for the detection of all the foodborne pathogens tested except Listeria monocytogenes. Although the lateral flow immunoprecipitation tests were statistically different from the culture methods for Salmonella and Listeria because of false-positive results, the tests did not produce any false negatives, indicating that this method would be suitable for screening meat and poultry products for these pathogens.

Evolution of the conceptual model of unsaturated zone hydrology at Yucca Mountain, Nevada

NASA Astrophysics Data System (ADS)

Flint, Alan L.; Flint, Lorraine E.; Bodvarsson, Gudmundur S.; Kwicklis, Edward M.; Fabryka-Martin, June

2001-06-01

Yucca Mountain is an arid site proposed for consideration as the United States' first underground high-level radioactive waste repository. Low rainfall (approximately 170 mm/yr) and a thick unsaturated zone (500-1000 m) are important physical attributes of the site because the quantity of water likely to reach the waste and the paths and rates of movement of the water to the saturated zone under future climates would be major factors in controlling the concentrations and times of arrival of radionuclides at the surrounding accessible environment. The framework for understanding the hydrologic processes that occur at this site and that control how quickly water will penetrate through the unsaturated zone to the water table has evolved during the past 15 yr. Early conceptual models assumed that very small volumes of water infiltrated into the bedrock (0.5-4.5 mm/yr, or 2-3 percent of rainfall), that much of the infiltrated water flowed laterally within the upper nonwelded units because of capillary barrier effects, and that the remaining water flowed down faults with a small amount flowing through the matrix of the lower welded, fractured rocks. It was believed that the matrix had to be saturated for fractures to flow. However, accumulating evidence indicated that infiltration rates were higher than initially estimated, such as infiltration modeling based on neutron borehole data, bomb-pulse isotopes deep in the mountain, perched water analyses and thermal analyses. Mechanisms supporting lateral diversion did not apply at these higher fluxes, and the flux calculated in the lower welded unit exceeded the conductivity of the matrix, implying vertical flow of water in the high permeability fractures of the potential repository host rock, and disequilibrium between matrix and fracture water potentials. The development of numerical modeling methods and parameter values evolved concurrently with the conceptual model in order to account for the observed field data, particularly fracture flow deep in the unsaturated zone. This paper presents the history of the evolution of conceptual models of hydrology and numerical models of unsaturated zone flow at Yucca Mountain, Nevada ( Flint, A.L., Flint, L.E., Kwicklis, E.M., Bodvarsson, G.S., Fabryka-Martin, J.M., 2001. Hydrology of Yucca Mountain. Reviews of Geophysics in press). This retrospective is the basis for recommendations for optimizing the efficiency with which a viable and robust conceptual model can be developed for a complex site.

Three-dimensional inspiratory flow in a double bifurcation airway model

NASA Astrophysics Data System (ADS)

Jalal, Sahar; Nemes, Andras; Van de Moortele, Tristan; Schmitter, Sebastian; Coletti, Filippo

2016-09-01

The flow in an idealized airway model is investigated for the steady inhalation case. The geometry consists of a symmetric planar double bifurcation that reflects the anatomical proportions of the human bronchial tree, and a wide range of physiologically relevant Reynolds numbers ( Re = 100-5000) is considered. Using magnetic resonance velocimetry, we analyze the three-dimensional fields of velocity and vorticity, along with flow descriptors that characterize the longitudinal and lateral dispersion. In agreement with previous studies, the symmetry of the flow partitioning is broken even at the lower Reynolds numbers, and at the second bifurcation, the fluid favors the medial branches over the lateral ones. This trend reaches a plateau around Re = 2000, above which the turbulent inflow results in smoothed mean velocity gradients. This also reduces the streamwise momentum flux, which is a measure of the longitudinal dispersion by the mean flow. The classic Dean-type counter-rotating vortices are observed in the first-generation daughter branches as a result of the local curvature. In the granddaughter branches, however, the secondary flows are determined by the local curvature only for the lower flow regimes ( Re ≤ 250), in which case the classic Dean mechanism prevails. At higher flow regimes, the field is instead dominated by streamwise vortices extending from the daughter into the medial granddaughter branches, where they rotate in the opposite direction with respect to Dean vortices. Circulation and secondary flow intensity show a similar trend as the momentum flux, increasing with Reynolds number up to Re = 2000 and then dropping due to turbulent dissipation of vorticity. The streamwise vortices interact both with each other and with the airway walls, and for Re > 500 they can become stronger in the medial granddaughter than in the upstream daughter branches. With respect to realistic airway models, the idealized geometry produces weaker secondary flows, suggesting that realistic anatomical features may generate more lateral dispersion than canonical symmetric models.

Calculation of three-dimensional compressible laminar and turbulent boundary layers. Calculation of three-dimensional compressible boundary layers on arbitrary wings

NASA Technical Reports Server (NTRS)

Cebeci, T.; Kaups, K.; Ramsey, J.; Moser, A.

1975-01-01

A very general method for calculating compressible three-dimensional laminar and turbulent boundary layers on arbitrary wings is described. The method utilizes a nonorthogonal coordinate system for the boundary-layer calculations and includes a geometry package that represents the wing analytically. In the calculations all the geometric parameters of the coordinate system are accounted for. The Reynolds shear-stress terms are modeled by an eddy-viscosity formulation developed by Cebeci. The governing equations are solved by a very efficient two-point finite-difference method used earlier by Keller and Cebeci for two-dimensional flows and later by Cebeci for three-dimensional flows.

Models of the diffuse radar backscatter from Mars

NASA Technical Reports Server (NTRS)

England, A. W.; Austin, R. T.

1991-01-01

The topographies of several debris flow units near the Mount St. Helens Volcano were measured at lateral scales of millimeters to meters in September 1990. The objective was to measure the surface roughness of the debris flows at scales smaller than, on the order of, and larger that the radar wavelength of common remote sensing radars. A laser profiling system and surveying instruments were used to obtain elevation data for square areas that varied in size from 10 to 32 cm. The elevation data were converted to estimates of the power spectrum of surface roughness. The conversions were based upon standard periodogram techniques, and upon a modified spectral estimation technique that was developed.

Seasonal Variation of Submesoscale Flow Features in a Mesoscale Eddy-dominant Region in the East Sea

NASA Astrophysics Data System (ADS)

Chang, Yeon S.; Choi, Byoung-Ju; Park, Young-Gyu

2018-03-01

Seasonal changes in the distribution of submesoscale (SM) flow features were examined using a fine-resolution numerical simulation. The SM flows are expected to be strong where mesoscale (MS) eddies actively develop and also when the mixed layer depth (MLD) is deep due to enhanced baroclinic instability. In the East Sea (ES), MS eddies more actively develop in summer while the MLD is deeper in winter, which provided the motivation to conduct this study to test the effects of MLD and MS eddies on the SM activity in this region. Finite-scale Liapunov exponents and the vertical velocity components were employed to analyze the SM activities. It was found that the SM intensity was marked by seasonality: it is stronger in winter when the mixed layer is deep but weaker in summer - despite the greater eddy kinetic energy. This is because in summer the mixed layer is so thin that there is not enough available potential energy. When the SM activity was quantified based on parameterization, (MLD × density gradient), it was determined that the seasonal variation of MLD plays a more important role than the lateral density gradient variation on SM flow motion in the ES.

Simulating Heterogeneous Infiltration and Contaminant leaching Processes at Chalk River, Ontario

NASA Astrophysics Data System (ADS)

Ali, M. A.; Ireson, A. M.; Keim, D.

2015-12-01

A study is conducted at a waste management area in Chalk River, Ontario to characterize flow and contaminant transport with the aim of contributing to improved hydrogeological risk assessment in the context of waste management. Field monitoring has been performed to gain insights into the unsaturated zone characteristics, moisture dynamics, and contaminant transport rates. The objective is to provide quantitative estimates of surface fluxes (quantification of infiltration and evaporation) and investigations of unsaturated zone processes controlling water infiltration and spatial variability in head distributions and flow rates. One particular issue is to examine the effectiveness of the clayey soil cap installed to prevent infiltration of water into the waste repository and the top sand soil cover above the clayey layer to divert the infiltrated water laterally. The spatial variability in the unsaturated zone properties and associated effects on water flow and contaminant transport observed at the site, have led to a concerted effort to develop improved model of flow and transport based on stochastic concepts. Results obtained through the unsaturated zone model investigations are combined with the hydrogeological and geochemical components and develop predictive tools to assess the long term fate of the contaminants at the waste management site.

Hydrocephalus secondary to obstruction of the lateral apertures in two dogs.

PubMed

Kent, M; Glass, E N; Haley, A C; Shaikh, L S; Sequel, M; Blas-Machado, U; Bishop, T M; Holmes, S P; Platt, S R

2016-11-01

Traditionally, hydrocephalus is divided into communicating or non-communicating (obstructive) based on the identification of a blockage of cerebrospinal fluid (CSF) flow through the ventricular system. Hydrocephalus ex vacuo refers to ventricular enlargement as a consequence of neuroparenchymal loss. Hydrocephalus related to obstruction of the lateral apertures of the fourth ventricles has rarely been described. The clinicopathologic findings in two dogs with hydrocephalus secondary to obstruction of the lateral apertures of the fourth ventricle are reported. Signs were associated with a caudal cervical spinal cord lesion in one dog and a caudal brain stem lesion in the other dog. Magnetic resonance imaging (MRI) disclosed dilation of the ventricular system, including the lateral recesses of the fourth ventricle. In one dog, postmortem ventriculography confirmed obstruction of the lateral apertures. Microscopic changes were identified in the choroid plexus in both dogs, yet a definitive cause of the obstructions was not identified. The MRI findings in both dogs are similar to membranous occlusion of the lateral and median apertures in human patients. MRI detection of dilation of the entire ventricular system in the absence of an identifiable cause should prompt consideration of an obstruction of the lateral apertures. In future cases, therapeutic interventions aimed at re-establishing CSF flow or ventriculoperitoneal catheterisation should be considered. © 2016 Australian Veterinary Association.

Local Modelling of Groundwater Flow Using Analytic Element Method Three-dimensional Transient Unconfined Groundwater Flow With Partially Penetrating Wells and Ellipsoidal Inhomogeneites

NASA Astrophysics Data System (ADS)

Jankovic, I.; Barnes, R. J.; Soule, R.

2001-12-01

The analytic element method is used to model local three-dimensional flow in the vicinity of partially penetrating wells. The flow domain is bounded by an impermeable horizontal base, a phreatic surface with recharge and a cylindrical lateral boundary. The analytic element solution for this problem contains (1) a fictitious source technique to satisfy the head and the discharge conditions along the phreatic surface, (2) a fictitious source technique to satisfy specified head conditions along the cylindrical boundary, (3) a method of imaging to satisfy the no-flow condition across the impermeable base, (4) the classical analytic solution for a well and (5) spheroidal harmonics to account for the influence of the inhomogeneities in hydraulic conductivity. Temporal variations of the flow system due to time-dependent recharge and pumping are represented by combining the analytic element method with a finite difference method: analytic element method is used to represent spatial changes in head and discharge, while the finite difference method represents temporal variations. The solution provides a very detailed description of local groundwater flow with an arbitrary number of wells of any orientation and an arbitrary number of ellipsoidal inhomogeneities of any size and conductivity. These inhomogeneities may be used to model local hydrogeologic features (such as gravel packs and clay lenses) that significantly influence the flow in the vicinity of partially penetrating wells. Several options for specifying head values along the lateral domain boundary are available. These options allow for inclusion of the model into steady and transient regional groundwater models. The head values along the lateral domain boundary may be specified directly (as time series). The head values along the lateral boundary may also be assigned by specifying the water-table gradient and a head value at a single point (as time series). A case study is included to demonstrate the application of the model in local modeling of the groundwater flow. Transient three-dimensional capture zones are delineated for a site on Prairie Island, MN. Prairie Island is located on the Mississippi River 40 miles south of the Twin Cities metropolitan area. The case study focuses on a well that has been known to contain viral DNA. The objective of the study was to assess the potential for pathogen migration toward the well.

National Airspace System Plan: Facilities, Equipment, Associated Development and Other Capital Needs

DTIC Science & Technology

1988-06-01

services will reflect a yes include: better balance between trip frequency and cost than would be the case under a closely regulated 0 Having an operating...terminal system). 0 Improved traffic flow planning and manage- ment, resulting in a more balanced workload. 0 A major improvement and integration of the...The AAS supervisors and specialists to assist them in will include AERA I functions and facilitate balancing sector staffing levels, later

Development of a Method to Downscale Soil Moisture Estimates Based on Topography and Other Site Characteristics

DTIC Science & Technology

2015-09-22

to relate to spatial variations in evapotranspiration (Western et al., 1999). All of these attributes are standardized and regressed against each...infiltration F, deep drainage or recharge to groundwater G, lateral flow L, and evapotranspiration E. The water balance is assumed to be at equilibrium...Temperature and insolation measurements were collected to determine the potential evapotranspiration (PET), which was calculated for each location type

An optofluidic metasurface for lateral flow-through detection of breast cancer biomarker.

PubMed

Wang, Yifei; Ali, Md Azahar; Chow, Edmond K C; Dong, Liang; Lu, Meng

2018-06-01

The rapid growth of point-of-care tests demands for biosensors with high sensitivity and small size. This paper demonstrates an optofluidic metasurface that combines silicon-on-insulator (SOI) nanophotonics and nanofluidics to realize a high-performance, lateral flow-through biosensor. The metasurface is made of a periodic array of silicon nanoposts on an SOI substrate, and functionalized with specific receptor molecules. Bonding of a polydimethylsiloxane slab directly onto the surface results in an ultracompact biosensor, where analyte solutions are restricted to flow only in the space between the nanoposts. No flow exists above the nanoposts. This sensor design overcomes the issue with diffusion-limited detection of many other biosensors. The lateral flow-through feature, in conjunction with high-Q resonance modes associated with optical bound states of the metasurface, offers an improved sensitivity to subtle molecule-bonding induced changes in refractive index. The device exhibits a resonance mode around 1550 nm wavelength and provides an index sensitivity of 720 nm/RIU. Biosensing is conducted to detect the epidermal growth factor receptor 2 (ErbB2), a protein biomarker for early-stage breast cancer screening, by monitoring resonance wavelength shifts in response to specific analyte-ligand binding events at the metasurface. The limit of detection of the device is 0.7 ng mL -1 for ErbB2. Copyright © 2018 Elsevier B.V. All rights reserved.

Influence of Forced Flow on the Dendritic Growth of Fe-C Alloy: 3D vs 2D Simulation

NASA Astrophysics Data System (ADS)

Wang, Weiling; Wang, Zhaohui; Luo, Sen; Ji, Cheng; Zhu, Miaoyong

2017-12-01

A 3D parallel cellular automaton-finite volume method (CA-FVM) model was used to simulate the equiaxed dendritic growth of an Fe-0.82 wt pct C alloy with xy- in- out and xyz- in- out type forced flows and the columnar dendritic growth with y- in- out type forced flow. In addition, the similarities and differences between the results of the 3D and 2D models are discussed and summarized in detail. The capabilities of the 3D and 2D CA-FVM models to predict the dendritic growth of the alloy with forced flow are validated through comparison with the boundary layer correction and Oseen-Ivanstov models, respectively. Because the forced flow can pass around perpendicular arms of the dendrites, the secondary arms at the sides upstream from the perpendicular arms are more developed than those on the upstream side of the upstream arms, especially at higher inlet velocities. In addition, compared to the xy- in- out case, the growth of the downstream arms is less inhibited and the secondary arms are more developed in the xyz- in- out case because of the greater lateral flow around their tips. Compared to the 3D case, the 2D equiaxed dendrites are more asymmetrical and lack secondary arms because of the thicker solute envelope. In the 3D case, the columnar dendrites on the upstream side (left one) are promoted, while the middle and downstream dendrites are inhibited in sequence. However, the sequential inhibition starts on the upstream side in the 2D case. This is mainly because the melt can pass around the upstream branch in 3D space. However, it can only climb over the upstream tip in 2D space. Additionally, the secondary arms show upstream development, which is more significant with increasing inlet velocity. The level of development of the secondary arms is also affected by the decay of the forced flow in the flow direction.

Application of the Shiono and Knight Method in asymmetric compound channels with different side slopes of the internal wall

NASA Astrophysics Data System (ADS)

Alawadi, Wisam; Al-Rekabi, Wisam S.; Al-Aboodi, Ali H.

2018-03-01

The Shiono and Knight Method (SKM) is widely used to predict the lateral distribution of depth-averaged velocity and boundary shear stress for flows in compound channels. Three calibrating coefficients need to be estimated for applying the SKM, namely eddy viscosity coefficient ( λ), friction factor ( f) and secondary flow coefficient ( k). There are several tested methods which can satisfactorily be used to estimate λ, f. However, the calibration of secondary flow coefficients k to account for secondary flow effects correctly is still problematic. In this paper, the calibration of secondary flow coefficients is established by employing two approaches to estimate correct values of k for simulating asymmetric compound channel with different side slopes of the internal wall. The first approach is based on Abril and Knight (2004) who suggest fixed values for main channel and floodplain regions. In the second approach, the equations developed by Devi and Khatua (2017) that relate the variation of the secondary flow coefficients with the relative depth ( β) and width ratio ( α) are used. The results indicate that the calibration method developed by Devi and Khatua (2017) is a better choice for calibrating the secondary flow coefficients than using the first approach which assumes a fixed value of k for different flow depths. The results also indicate that the boundary condition based on the shear force continuity can successfully be used for simulating rectangular compound channels, while the continuity of depth-averaged velocity and its gradient is accepted boundary condition in simulations of trapezoidal compound channels. However, the SKM performance for predicting the boundary shear stress over the shear layer region may not be improved by only imposing the suitable calibrated values of secondary flow coefficients. This is because difficulties of modelling the complex interaction that develops between the flows in the main channel and on the floodplain in this region.

Graphical method for determining the coefficient of consolidation cv from a flow-pump permeability test

USGS Publications Warehouse

Morin, Roger H.; Olsen, Harold W.; Nelson, Karl R.; Gill, James D.

1989-01-01

A graphical method has been developed for determining the coefficient of consolidation from the transient phases of a flow-pump permeability test. The flow pump can be used to infuse fluid into or withdraw fluid from a laboratory sediment specimen at a constant volumetric rate in order to obtain data that can be used to calculate permeability using Darcy's law. Representative type-curve solutions to the associated forced-flow and pressure-decay models are derived. These curves provide the basis for graphically evaluating the permeability k, the coefficient of consolidation cv, and the coefficient of volume change mv. The curve-matching technique is easy and rapid. Values of k, cv and mv for a laterally confined kaolinite specimen were determined by this graphical method and appear to be in reasonably good agreement with numerically derived estimates (within 20%). Discrepancies between the two sets of results seem to be largely a function of data quality.

Statistical assessment of optical phase fluctuations through turbulent mixing layers

NASA Astrophysics Data System (ADS)

Gardner, Patrick J.; Roggemann, Michael C.; Welsh, Byron M.; Bowersox, Rodney D.

1995-09-01

A lateral shearing interferometer is used to measure the slope of perturbed wavefronts after propagating through turbulent shear flows. This provides a two-dimensional flow visualization technique which is nonintrusive. The slope measurements are used to reconstruct the phase of the turbulence-corrupted wave front. Experiments were performed on a plane shear mixing layer of helium and nitrogen gas at fixed velocities, for five locations in the flow development. The two gases, having a density ratio of approximately seven, provide an effective means of simulating compressible shear layers. Statistical autocorrelation functions and structure functions are computed on the reconstructed phase maps. The autocorrelation function results indicate that the turbulence-induced phase fluctuations are not wide-sense stationary. The structure functions exhibit statistical homogeneity, indicating the phase fluctuation are stationary in first increments. However, the turbulence-corrupted phase is not isotropic. A five-thirds power law is shown to fit one-dimensional, orthogonal slices of the structure function, with scaling coefficients related to the location in the flow.

Simulation of hydrodynamics, temperature, and dissolved oxygen in Beaver Lake, Arkansas, 1994-1995

USGS Publications Warehouse

Haggard, Brian; Green, W. Reed

2002-01-01

The tailwaters of Beaver Lake and other White River reservoirs support a cold-water trout fishery of significant economic yield in northwestern Arkansas. The Arkansas Game and Fish Commission has requested an increase in existing minimum flows through the Beaver Lake dam to increase the amount of fishable waters downstream. Information is needed to assess the impact of additional minimum flows on temperature and dissolved-oxygen qualities of reservoir water above the dam and the release water. A two-dimensional, laterally averaged hydrodynamic, thermal and dissolved-oxygen model was developed and calibrated for Beaver Lake, Arkansas. The model simulates surface-water elevation, currents, heat transport and dissolved-oxygen dynamics. The model was developed to assess the impacts of proposed increases in minimum flows from 1.76 cubic meters per second (the existing minimum flow) to 3.85 cubic meters per second (the additional minimum flow). Simulations included assessing (1) the impact of additional minimum flows on tailwater temperature and dissolved-oxygen quality and (2) increasing initial water-surface elevation 0.5 meter and assessing the impact of additional minimum flow on tailwater temperatures and dissolved-oxygen concentrations. The additional minimum flow simulation (without increasing initial pool elevation) appeared to increase the water temperature (<0.9 degrees Celsius) and decrease dissolved oxygen concentration (<2.2 milligrams per liter) in the outflow discharge. Conversely, the additional minimum flow plus initial increase in pool elevation (0.5 meter) simulation appeared to decrease outflow water temperature (0.5 degrees Celsius) and increase dissolved oxygen concentration (<1.2 milligrams per liter) through time. However, results from both minimum flow scenarios for both water temperature and dissolved oxygen concentration were within the boundaries or similar to the error between measured and simulated water column profile values.

Migration of Amphitheater-Headed Valleys in Kauai Basalts: Wailua Falls as a Case Example

NASA Astrophysics Data System (ADS)

Pederson, D. T.; Blay, C.

2006-12-01

Amphitheater-headed valleys in Kauai basalts migrate upstream primarily because of weathering processes. Basalt weathering rates are enhanced by the presence of water and/or vegetation. When both weathering process are present, weathering rates are greater than the sum of the two processes. Because waterfalls can create an environment where vegetation growth is greatly inhibited by the impact of falling water, weathering rates may be much greater on each side of the falls where vegetation can grow. Sources of water for weathering include groundwater discharge, waterfall spray, and condensation of atmospheric water. Because basalts weather rapidly in tropical environments, streams require only the capability to transport smaller particle sizes to sustain amphitheater migration. It should be noted that most waterfalls occupy only a small fraction of the amphitheater head which further supports weathering as the principal agent in amphitheater development and migration. Lava flows building shield volcanos are usually episodic with crystallization and possible weathering occurring before the next flow. The rate of cooling of a flow determines the crystal size of minerals and in combination with the magma chemistry the susceptibility of a flow to weathering process as well as the strength of the rock. With time, soils and topography will develop on the now crystallized flow. Because clays are a product of basalt weathering, soils when buried by later flows, represent low permeability layers. Additionally, new flows may follow (and bury) surface drainage systems resulting in localized thicker flows that cool more slowly and have different properties then the adjacent thinner flows. Consequently, most amphitheater heads have significant heterogenieties, especially in a vertical section representing multiple basalt flows. Wailua Falls on Kauai will be used as a field example of amphitheater weathering processes and migration.

Measurements of Shear Lift Force on a Bubble in Channel Flow in Microgravity

NASA Technical Reports Server (NTRS)

Nahra, Henry K.; Motil, Brian J.; Skor, Mark

2003-01-01

Under microgravity conditions, the shear lift force acting on bubbles, droplets or solid particles in multiphase flows becomes important because under normal gravity, this hydrodynamic force is masked by buoyancy. This force plays an important role in furnishing the detachment process of bubbles in a setting where a bubble suspension is needed in microgravity. In this work, measurements of the shear lift force acting on a bubble in channel flow are performed. The shear lift force is deduced from the bubble kinematics using scaling and then compared with predictions from models in literature that address different asymptotic and numerical solutions. Basic trajectory calculations are then performed and the results are compared with experimental data of position of the bubble in the channel. A direct comparison of the lateral velocity of the bubbles is also made with the lateral velocity prediction from investigators, whose work addressed the shear lift on a sphere in different two-dimensional shear flows including Poiseuille flow.

Rapid Detection of Escherichia coli O157 and Shiga Toxins by Lateral Flow Immunoassays

PubMed Central

Wang, Jinliang; Katani, Robab; Li, Lingling; Hegde, Narasimha; Roberts, Elisabeth L.; Kapur, Vivek; DebRoy, Chitrita

2016-01-01

Shiga toxin-producing Escherichia coli O157:H7 (STEC) cause food-borne illness that may be fatal. STEC strains enumerate two types of potent Shiga toxins (Stx1 and Stx2) that are responsible for causing diseases. It is important to detect the E. coli O157 and Shiga toxins in food to prevent outbreak of diseases. We describe the development of two multi-analyte antibody-based lateral flow immunoassays (LFIA); one for the detection of Stx1 and Stx2 and one for the detection of E. coli O157 that may be used simultaneously to detect pathogenic E. coli O157:H7. The LFIA strips were developed by conjugating nano colloidal gold particles with monoclonal antibodies against Stx1 and Stx2 and anti-lipid A antibodies to capture Shiga toxins and O157 antigen, respectively. Our results indicate that the LFIA for Stx is highly specific and detected Stx1 and Stx2 within three hours of induction of STEC with ciprofloxacin at 37 °C. The limit of detection for E. coli O157 LFIA was found to be 105 CFU/mL in ground beef spiked with the pathogen. The LFIAs are rapid, accurate and easy to use and do not require sophisticated equipment or trained personnel. Following the assay, colored bands on the membrane develop for end-point detection. The LFIAs may be used for screening STEC in food and the environment. PMID:27023604

Development and Validation of a Lateral Flow Immunoassay Test Kit for Dual Detection of Casein and β-Lactoglobulin Residues.

PubMed

Masiri, Jongkit; Barrios-Lopez, Brianda; Benoit, Lora; Tamayo, Joshua; Day, Jeffrey; Nadala, Cesar; Sung, Shao-Lei; Samadpour, Mansour

2016-03-01

Allergies to cow's milk are very common and can present as life-threatening anaphylaxis. Consequently, food labeling legislation mandates that foods containing milk residues, including casein and/or β-lactoglobulin, provide an indication of such on the product label. Because contamination with either component independent of the other can occur during food manufacturing, effective allergen management measures for containment of milk residues necessitates the use of dual screening methods. To assist the food industry in improving food safety practices, we have developed a rapid lateral flow immunoassay test kit that reliably reports both residues down to 0.01 μg per swab and 0.1 ppm of protein for foods. The assay utilizes both sandwich and competitive format test lines and is specific for bovine milk residues. Selectivity testing using a panel of matrices with potentially interfering substances, including commonly used sanitizing agents, indicated reduction in the limit of detection by one-to fourfold. With food, residues were easily detected in all cow's milk-based foods tested, but goat and sheep milk residues were not detected. Specificity analysis revealed no cross-reactivity with common commodities, with the exception of kidney beans when present at high concentrations (> 1%). The development of a highly sensitive and rapid test method capable of detecting trace amounts of casein and/or β-lactoglobulin should aid food manufacturers and regulatory agencies in monitoring for milk allergens in environmental and food samples.

Cftr controls lumen expansion and function of Kupffer’s vesicle in zebrafish

PubMed Central

Navis, Adam; Marjoram, Lindsay; Bagnat, Michel

2013-01-01

Regulated fluid secretion is crucial for the function of most organs. In vertebrates, the chloride channel cystic fibrosis transmembrane conductance regulator (CFTR) is a master regulator of fluid secretion. Although the biophysical properties of CFTR have been well characterized in vitro, little is known about its in vivo role during development. Here, we investigated the function of Cftr during zebrafish development by generating several cftr mutant alleles using TAL effector nucleases. We found that loss of cftr function leads to organ laterality defects. In zebrafish, left-right (LR) asymmetry requires cilia-driven fluid flow within the lumen of Kupffer’s vesicle (KV). Using live imaging we found that KV morphogenesis is disrupted in cftr mutants. Loss of Cftr-mediated fluid secretion impairs KV lumen expansion leading to defects in organ laterality. Using bacterial artificial chromosome recombineering, we generated transgenic fish expressing functional Cftr fusion proteins with fluorescent tags under the control of the cftr promoter. The transgenes completely rescued the cftr mutant phenotype. Live imaging of these transgenic lines showed that Cftr is localized to the apical membrane of the epithelial cells in KV during lumen formation. Pharmacological stimulation of Cftr-dependent fluid secretion led to an expansion of the KV lumen. Conversely, inhibition of ion gradient formation impaired KV lumen inflation. Interestingly, cilia formation and motility in KV were not affected, suggesting that fluid secretion and flow are independently controlled in KV. These findings uncover a new role for cftr in KV morphogenesis and function during zebrafish development. PMID:23487313

Does disseminated nontuberculous mycobacterial disease cause false-positive Determine B-LAM lateral flow assay results? A retrospective review.

PubMed

Nel, Jeremy S; Lippincott, Christopher K; Berhanu, Rebecca; Spencer, David C; Sanne, Ian M; Ive, Prudence

2017-06-02

We retrospectively reviewed the Determine TB-LAM lateral flow assay (LF-LAM) results among HIV-infected patients with disseminated nontuberculous mycobacterial (NTM) disease. LF-LAM was positive in 19/21 patients without evidence of tuberculosis coinfection. Although tuberculosis-NTM coinfection may have been underdiagnosed, our results suggest that disseminated NTM disease may cause false-positive LF-LAM results. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

Evaluation of a Cryptococcal antigen Lateral Flow Assay in serum and cerebrospinal fluid for rapid diagnosis of cryptococcosis in Colombia.

PubMed

Cáceres, Diego H; Zuluaga, Alejandra; Tabares, Ángela M; Chiller, Tom; González, Ángel; Gómez, Beatriz L

2017-12-21

A Lateral Flow Assay to detect cryptococcal antigen (CrAg® LFA) in serum and cerebrospinal fluid for the rapid diagnosis of cryptococcosis was evaluated. A retrospective validation was performed. Sensitivity and specificity of the CrAg® LFA was 100%. High concordance (kappa index=1.0) between Cryptococcal Antigen Latex Agglutination System (CALAS®) and CrAg® LFA was observed. CrAg® LFA showed higher analytical sensitivity for detecting low concentrations of cryptococcal antigen.

Evaluation of a Cryptococcal antigen Lateral Flow Assay in serum and cerebrospinal fluid for rapid diagnosis of cryptococcosis in Colombia

PubMed Central

Cáceres, Diego H.; Zuluaga, Alejandra; Tabares, Ángela M.; Chiller, Tom; González, Ángel; Gómez, Beatriz L.

2017-01-01

ABSTRACT A Lateral Flow Assay to detect cryptococcal antigen (CrAg® LFA) in serum and cerebrospinal fluid for the rapid diagnosis of cryptococcosis was evaluated. A retrospective validation was performed. Sensitivity and specificity of the CrAg® LFA was 100%. High concordance (kappa index=1.0) between Cryptococcal Antigen Latex Agglutination System (CALAS®) and CrAg® LFA was observed. CrAg® LFA showed higher analytical sensitivity for detecting low concentrations of cryptococcal antigen. PMID:29267584

Porosity Development in a Coastal Setting: A Reactive Transport Model to Assess the Influence of Heterogeneity of Hydrological, Geochemical and Lithological Conditions

NASA Astrophysics Data System (ADS)

Maqueda, A.; Renard, P.; Cornaton, F. J.

2014-12-01

Coastal karst networks are formed by mineral dissolution, mainly calcite, in the freshwater-saltwater mixing zone. The problem has been approached first by studying the kinetics of calcite dissolution and then coupling ion-pairing software with flow and mass transport models. Porosity development models require high computational power. A workaround to reduce computational complexity is to assume the calcite dissolution reaction is relatively fast, thus equilibrium chemistry can be used to model it (Sanford & Konikow, 1989). Later developments allowed the full coupling of kinetics and transport in a model. However kinetics effects of calcite dissolution were found negligible under the single set of assumed hydrological and geochemical boundary conditions. A model is implemented with the coupling of FeFlow software as the flow & transport module and PHREEQC4FEFLOW (Wissmeier, 2013) ion-pairing module. The model is used to assess the influence of heterogeneities in hydrological, geochemical and lithological boundary conditions on porosity evolution. The hydrologic conditions present in the karst aquifer of Quintana Roo coast in Mexico are used as a guide for generating inputs for simulations.

Thin and open vessel windows for intra-vital fluorescence imaging of murine cochlear blood flow.

PubMed

Shi, Xiaorui; Zhang, Fei; Urdang, Zachary; Dai, Min; Neng, Lingling; Zhang, Jinhui; Chen, Songlin; Ramamoorthy, Sripriya; Nuttall, Alfred L

2014-07-01

Normal microvessel structure and function in the cochlea is essential for maintaining the ionic and metabolic homeostasis required for hearing function. Abnormal cochlear microcirculation has long been considered an etiologic factor in hearing disorders. A better understanding of cochlear blood flow (CoBF) will enable more effective amelioration of hearing disorders that result from aberrant blood flow. However, establishing the direct relationship between CoBF and other cellular events in the lateral wall and response to physio-pathological stress remains a challenge due to the lack of feasible interrogation methods and difficulty in accessing the inner ear. Here we report on new methods for studying the CoBF in a mouse model using a thin or open vessel-window in combination with fluorescence intra-vital microscopy (IVM). An open vessel-window enables investigation of vascular cell biology and blood flow permeability, including pericyte (PC) contractility, bone marrow cell migration, and endothelial barrier leakage, in wild type and fluorescent protein-labeled transgenic mouse models with high spatial and temporal resolution. Alternatively, the thin vessel-window method minimizes disruption of the homeostatic balance in the lateral wall and enables study CoBF under relatively intact physiological conditions. A thin vessel-window method can also be used for time-based studies of physiological and pathological processes. Although the small size of the mouse cochlea makes surgery difficult, the methods are sufficiently developed for studying the structural and functional changes in CoBF under normal and pathological conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

Assessment of the hydrogeology and water quality in a near-shore well field, Sarasota, Florida

USGS Publications Warehouse

Broska, J.C.; Knochenmus, L.A.

1996-01-01

The city of Sarasota, Florida, operates a downtown well field that pumps mineralized water from ground water sources to supply a reverse osmosis plant. Because of the close proximity of the well field to Sarasota Bay and the high sulfate and chloride concentrations of ground-water supplies, a growing concern exists about the possibility of lateral movement of saltwater in a landward direction (intrusion) and vertical movement of relict sea water (upconing). In 1992, the U.S. Geological Survey began a 3-year study to evaluate the hydraulic characteristics and water quality of ground-water resources within the downtown well field and the surrounding 235-square-mile study area. Delineation of the hydrogeology of the study area was based on water- quality data, aquifer test data, and extensive borehole geophysical surveys (including gamma, caliper, temperature, electrical resistivity, and flow meter logs) from the six existing production wells and from a corehole drilled as part of the study, as well as from published and unpublished reports on file at the U.S. Geological Survey, the Southwest Florida Water Management District, and consultant's reports. Water-quality data were examined for spatial and temporal trends that might relate to the mechanism for observed water-quality changes. Water quality in the study area appears to be dependent upon several mechanisms, including upconing of higher salinity water from deeper zones within the aquifer system, interbore-hole flow between zones of varying water quality through improperly cased and corroded wells, migration of highly mineralized waters through structural deformities, and the presence of unflushed relict seawater. A numerical ground-water flow model was developed as an interpretative tool where field-derived hydrologic characteristics could be tested. The conceptual model consisted of seven layers to represent the multilayered aquifer systems underlying the study area. Particle tracking was utilized to delineate the travel path of water as it enters the model area under a set of given conditions. Within the model area, simulated flow in the intermediate aquifer system originates primarily from the northwestern boundary. Simulated flow in the Upper Floridan aquifer originates in lower model layers (deeper flow zones) and ultimately can be traced to the southeastern and northwestern boundaries. Volumetric budgets calculated from numerical simulation of a hypothetical well field indicate that the area of contribution to the well field changes seasonally. Although ground-water flow patterns change with wet and dry seasons, most water enters the well-field flow system through lower parts of the Upper Floridan aquifer from a southeastern direction. Moreover, particle tracking indicated that ground-water flow paths with strictly lateral pathlines in model layers correspond to the intermediate aquifer system, whereas particles traced through model layers corresponding to the Upper Floridan aquifer had components of vertical and lateral flow.

Modeling post-wildfire hydrological processes with ParFlow

NASA Astrophysics Data System (ADS)

Escobar, I. S.; Lopez, S. R.; Kinoshita, A. M.

2017-12-01

Wildfires alter the natural processes within a watershed, such as surface runoff, evapotranspiration rates, and subsurface water storage. Post-fire hydrologic models are typically one-dimensional, empirically-based models or two-dimensional, conceptually-based models with lumped parameter distributions. These models are useful for modeling and predictions at the watershed outlet; however, do not provide detailed, distributed hydrologic processes at the point scale within the watershed. This research uses ParFlow, a three-dimensional, distributed hydrologic model to simulate post-fire hydrologic processes by representing the spatial and temporal variability of soil burn severity (via hydrophobicity) and vegetation recovery. Using this approach, we are able to evaluate the change in post-fire water components (surface flow, lateral flow, baseflow, and evapotranspiration). This work builds upon previous field and remote sensing analysis conducted for the 2003 Old Fire Burn in Devil Canyon, located in southern California (USA). This model is initially developed for a hillslope defined by a 500 m by 1000 m lateral extent. The subsurface reaches 12.4 m and is assigned a variable cell thickness to explicitly consider soil burn severity throughout the stages of recovery and vegetation regrowth. We consider four slope and eight hydrophobic layer configurations. Evapotranspiration is used as a proxy for vegetation regrowth and is represented by the satellite-based Simplified Surface Energy Balance (SSEBOP) product. The pre- and post-fire surface runoff, subsurface storage, and surface storage interactions are evaluated at the point scale. Results will be used as a basis for developing and fine-tuning a watershed-scale model. Long-term simulations will advance our understanding of post-fire hydrological partitioning between water balance components and the spatial variability of watershed processes, providing improved guidance for post-fire watershed management. In reference to the presenter, Isabel Escobar: Research is funded by the NASA-DIRECT STEM Program. Travel expenses for this presentation is funded by CSU-LSAMP. CSU-LSAMP is supported by the National Science Foundation under Grant # HRD-1302873 and the CSU Office of Chancellor.

Experimental and numerical models of three-dimensional gravity-driven flow of shear-thinning polymer solutions used in vaginal delivery of microbicides.

PubMed

Kheyfets, Vitaly O; Kieweg, Sarah L

2013-06-01

HIV/AIDS is a growing global pandemic. A microbicide is a formulation of a pharmaceutical agent suspended in a delivery vehicle, and can be used by women to protect themselves against HIV infection during intercourse. We have developed a three-dimensional (3D) computational model of a shear-thinning power-law fluid spreading under the influence of gravity to represent the distribution of a microbicide gel over the vaginal epithelium. This model, accompanied by a new experimental methodology, is a step in developing a tool for optimizing a delivery vehicle's structure/function relationship for clinical application. We compare our model with experiments in order to identify critical considerations for simulating 3D free-surface flows of shear-thinning fluids. Here we found that neglecting lateral spreading, when modeling gravity-induced flow, resulted in up to 47% overestimation of the experimental axial spreading after 90 s. In contrast, the inclusion of lateral spreading in 3D computational models resulted in rms errors in axial spreading under 7%. In addition, the choice of the initial condition for shape in the numerical simulation influences the model's ability to describe early time spreading behavior. Finally, we present a parametric study and sensitivity analysis of the power-law parameters' influence on axial spreading, and to examine the impact of changing rheological properties as a result of dilution or formulation conditions. Both the shear-thinning index (n) and consistency (m) impacted the spreading length and deceleration of the moving front. The sensitivity analysis showed that gels with midrange m and n values (for the ranges in this study) would be most sensitive (over 8% changes in spreading length) to 10% changes (e.g., from dilution) in both rheological properties. This work is applicable to many industrial and geophysical thin-film flow applications of non-Newtonian fluids; in addition to biological applications in microbicide drug delivery.

Experimental and Numerical Models of Three-Dimensional Gravity-Driven Flow of Shear-Thinning Polymer Solutions Used in Vaginal Delivery of Microbicides

PubMed Central

Kheyfets, Vitaly O.; Kieweg, Sarah L.

2013-01-01

HIV/AIDS is a growing global pandemic. A microbicide is a formulation of a pharmaceutical agent suspended in a delivery vehicle, and can be used by women to protect themselves against HIV infection during intercourse. We have developed a three-dimensional (3D) computational model of a shear-thinning power-law fluid spreading under the influence of gravity to represent the distribution of a microbicide gel over the vaginal epithelium. This model, accompanied by a new experimental methodology, is a step in developing a tool for optimizing a delivery vehicle's structure/function relationship for clinical application. We compare our model with experiments in order to identify critical considerations for simulating 3D free-surface flows of shear-thinning fluids. Here we found that neglecting lateral spreading, when modeling gravity-induced flow, resulted in up to 47% overestimation of the experimental axial spreading after 90 s. In contrast, the inclusion of lateral spreading in 3D computational models resulted in rms errors in axial spreading under 7%. In addition, the choice of the initial condition for shape in the numerical simulation influences the model's ability to describe early time spreading behavior. Finally, we present a parametric study and sensitivity analysis of the power-law parameters' influence on axial spreading, and to examine the impact of changing rheological properties as a result of dilution or formulation conditions. Both the shear-thinning index (n) and consistency (m) impacted the spreading length and deceleration of the moving front. The sensitivity analysis showed that gels with midrange m and n values (for the ranges in this study) would be most sensitive (over 8% changes in spreading length) to 10% changes (e.g., from dilution) in both rheological properties. This work is applicable to many industrial and geophysical thin-film flow applications of non-Newtonian fluids; in addition to biological applications in microbicide drug delivery. PMID:23699721

Centrifugal study of zone of influence during air-sparging.

PubMed

Hu, Liming; Meegoda, Jay N; Du, Jianting; Gao, Shengyan; Wu, Xiaofeng

2011-09-01

Air sparging (AS) is one of the groundwater remediation techniques for remediating volatile organic compounds (VOCs) in saturated soil. However, in spite of the success of air sparging as a remediation technique for the cleanup of contaminated soils, to date, the fundamental mechanisms or the physics of air flow through porous media is not well understood. In this study, centrifugal modeling tests were performed to investigate air flow rates and the evolution of the zone of influence during the air sparging under various g-levels. The test results show that with the increase in sparging pressure the mass flow rate of the air sparging volume increases. The air mass flow rate increases linearly with the effective sparging pressure ratio, which is the difference between sparging pressure and hydrostatic pressure normalized with respect to the effective overburden pressure at the sparging point. Also the slope of mass flow rate with effective sparging pressure ratio increases with higher g-levels. This variation of the slope of mass flow rate of air sparging volume versus effective sparging pressure ratio, M, is linear with g-level confirming that the air flow through soil for a given effective sparging pressure ratio only depends on the g-level. The test results also show that with increasing sparging pressure, the zone of influence (ZOI), which consists of the width at the tip of the cone or lateral intrusion and the cone angle, will lead to an increase in both lateral intrusion and the cone angle. With a further increase in air injection pressure, the cone angle reaches a constant value while the lateral intrusion becomes the main contributor to the enlargement of the ZOI. However, beyond a certain value of effective sparging pressure ratio, there is no further enlargement of the ZOI.

Interaction Between Downwelling Flow and the Laterally-Varying Thickness of the North American Lithosphere Inferred from Seismic Anisotropy

NASA Astrophysics Data System (ADS)

Behn, M. D.; Conrad, C. P.; Silver, P. G.

2005-12-01

Shear flow in the asthenosphere tends to align olivine crystals in the direction of shear, producing a seismically anisotropic asthenosphere that can be detected using a number of seismic techniques (e.g., shear-wave splitting (SWS) and surface waves). In the ocean basins, where the asthenosphere has a relatively uniform thickness and lithospheric anisotropy appears to be small, observed azimuthal anisotropy is well fit by asthenospheric shear flow in global flow models driven by a combination of plate motions and mantle density heterogeneity. In contrast, beneath the continents both the lithospheric ceiling and asthenospheric thickness may vary considerably across cratonic regions and ocean-continent boundaries. To examine the influence of a continental lithosphere with variable thickness on predictions of continental seismic anisotropy, we impose lateral variations in lithospheric viscosity in global models of mantle flow driven by plate motions and mantle density heterogeneity. For the North American continent, the Farallon slab descends beneath a deep cratonic root, producing downwelling flow in the upper mantle and convergent flow beneath the cratonic lithosphere. We evaluate both the orientation of the predicted azimuthal anisotropy and the depth dependence of radial anisotropy for this downwelling flow and find that the inclusion of a strong continental root provides an improved fit to observed SWS observations beneath the North American craton. Thus, we hypothesize that at least some continental anisotropy is associated with sub-lithospheric viscous shear, although fossil anisotropy in the lithospheric layer may also contribute significantly. Although we do not observe significant variations in the direction of predicted anisotropy with depth, we do find that the inclusion of deep continental roots pushes the depth of the anisotropy layer deeper into the upper mantle. We test several different models of laterally-varying lithosphere and asthenosphere viscosity. These models can be used to separate the contributions of asthenospheric flow and lithospheric fossil fabric in observations of continental anisotropy.

Overview for Design and Construction of Drilled Shafts in Cohesive Soils.

DTIC Science & Technology

1981-08-01

water flowing around supporting columns of bridges. Methods for determining the lateral load -deflection behavior of drilled shafts are based on solutions...PROCEDURES. ..... ............... 22 Axial Load Behavior of Single Shafts .... ......... 22 Lateral Load Behavior of Single Shafts .... ........ 54 Load ...on the shaft (Patey 1977, Claessen and Horvat 1974). Large-diameter shafts can be more easily constructed to resist lateral loads than driven piles or

Bumblebee flight performance in environments of different proximity.

PubMed

Linander, Nellie; Baird, Emily; Dacke, Marie

2016-02-01

Flying animals are capable of navigating through environments of different complexity with high precision. To control their flight when negotiating narrow tunnels, bees and birds use the magnitude of apparent image motion (known as optic flow) generated by the walls. In their natural habitat, however, these animals would encounter both cluttered and open environments. Here, we investigate how large changes in the proximity of nearby surfaces affect optic flow-based flight control strategies. We trained bumblebees to fly along a flight and recorded how the distance between the walls--from 60 cm to 240 cm--affected their flight control. Our results reveal that, as tunnel width increases, both lateral position and ground speed become increasingly variable. We also find that optic flow information from the ground has an increasing influence on flight control, suggesting that bumblebees measure optic flow flexibly over a large lateral and ventral field of view, depending on where the highest magnitude of optic flow occurs. A consequence of this strategy is that, when flying in narrow spaces, bumblebees use optic flow information from the nearby obstacles to control flight, while in more open spaces they rely primarily on optic flow cues from the ground.

Root gravitropism is regulated by a transient lateral auxin gradient controlled by a tipping-point mechanism

PubMed Central

Band, Leah R.; Wells, Darren M.; Larrieu, Antoine; Sun, Jianyong; Middleton, Alistair M.; French, Andrew P.; Brunoud, Géraldine; Sato, Ethel Mendocilla; Wilson, Michael H.; Péret, Benjamin; Oliva, Marina; Swarup, Ranjan; Sairanen, Ilkka; Parry, Geraint; Ljung, Karin; Beeckman, Tom; Garibaldi, Jonathan M.; Estelle, Mark; Owen, Markus R.; Vissenberg, Kris; Hodgman, T. Charlie; Pridmore, Tony P.; King, John R.; Vernoux, Teva; Bennett, Malcolm J.

2012-01-01

Gravity profoundly influences plant growth and development. Plants respond to changes in orientation by using gravitropic responses to modify their growth. Cholodny and Went hypothesized over 80 years ago that plants bend in response to a gravity stimulus by generating a lateral gradient of a growth regulator at an organ's apex, later found to be auxin. Auxin regulates root growth by targeting Aux/IAA repressor proteins for degradation. We used an Aux/IAA-based reporter, domain II (DII)-VENUS, in conjunction with a mathematical model to quantify auxin redistribution following a gravity stimulus. Our multidisciplinary approach revealed that auxin is rapidly redistributed to the lower side of the root within minutes of a 90° gravity stimulus. Unexpectedly, auxin asymmetry was rapidly lost as bending root tips reached an angle of 40° to the horizontal. We hypothesize roots use a “tipping point” mechanism that operates to reverse the asymmetric auxin flow at the midpoint of root bending. These mechanistic insights illustrate the scientific value of developing quantitative reporters such as DII-VENUS in conjunction with parameterized mathematical models to provide high-resolution kinetics of hormone redistribution. PMID:22393022

Root gravitropism is regulated by a transient lateral auxin gradient controlled by a tipping-point mechanism.

PubMed

Band, Leah R; Wells, Darren M; Larrieu, Antoine; Sun, Jianyong; Middleton, Alistair M; French, Andrew P; Brunoud, Géraldine; Sato, Ethel Mendocilla; Wilson, Michael H; Péret, Benjamin; Oliva, Marina; Swarup, Ranjan; Sairanen, Ilkka; Parry, Geraint; Ljung, Karin; Beeckman, Tom; Garibaldi, Jonathan M; Estelle, Mark; Owen, Markus R; Vissenberg, Kris; Hodgman, T Charlie; Pridmore, Tony P; King, John R; Vernoux, Teva; Bennett, Malcolm J

2012-03-20

Gravity profoundly influences plant growth and development. Plants respond to changes in orientation by using gravitropic responses to modify their growth. Cholodny and Went hypothesized over 80 years ago that plants bend in response to a gravity stimulus by generating a lateral gradient of a growth regulator at an organ's apex, later found to be auxin. Auxin regulates root growth by targeting Aux/IAA repressor proteins for degradation. We used an Aux/IAA-based reporter, domain II (DII)-VENUS, in conjunction with a mathematical model to quantify auxin redistribution following a gravity stimulus. Our multidisciplinary approach revealed that auxin is rapidly redistributed to the lower side of the root within minutes of a 90° gravity stimulus. Unexpectedly, auxin asymmetry was rapidly lost as bending root tips reached an angle of 40° to the horizontal. We hypothesize roots use a "tipping point" mechanism that operates to reverse the asymmetric auxin flow at the midpoint of root bending. These mechanistic insights illustrate the scientific value of developing quantitative reporters such as DII-VENUS in conjunction with parameterized mathematical models to provide high-resolution kinetics of hormone redistribution.

Development of a POC Test for TB Based on Multiple Immunodominant Epitopes of M. tuberculosis Specific Cell-Wall Proteins

PubMed Central

Gonzalez, Jesus M.; Francis, Bryan; Burda, Sherri; Hess, Kaitlyn; Behera, Digamber; Gupta, Dheeraj; Agarwal, Ashutosh Nath; Verma, Indu; Verma, Ajoy; Myneedu, Vithal Prasad; Niedbala, Sam; Laal, Suman

2014-01-01

The need for an accurate, rapid, simple and affordable point-of-care (POC) test for Tuberculosis (TB) that can be implemented in microscopy centers and other peripheral health-care settings in the TB-endemic countries remains unmet. This manuscript describes preliminary results of a new prototype rapid lateral flow TB test based on detection of antibodies to immunodominant epitopes (peptides) derived from carefully selected, highly immunogenic M. tuberculosis cell-wall proteins. Peptide selection was initially based on recognition by antibodies in sera from TB patients but not in PPD-/PPD+/BCG-vaccinated individuals from TB-endemic settings. The peptides were conjugated to BSA; the purified peptide-BSA conjugates striped onto nitrocellulose membrane and adsorbed onto colloidal gold particles to devise the prototype test, and evaluated for reactivity with sera from 3 PPD-, 29 PPD+, 15 PPD-unknown healthy subjects, 10 patients with non-TB lung disease and 124 smear-positive TB patients. The assay parameters were adjusted to determine positive/negative status within 15 minutes via visual or instrumented assessment. There was minimal or no reactivity of sera from non-TB subjects with the striped BSA-peptides demonstrating the lack of anti-peptide antibodies in subjects with latent TB and/or BCG vaccination. Sera from most TB patients demonstrated reactivity with one or more peptides. The sensitivity of antibody detection ranged from 28–85% with the 9 BSA-peptides. Three peptides were further evaluated with sera from 400 subjects, including additional PPD-/PPD+/PPD-unknown healthy contacts, close hospital contacts and household contacts of untreated TB patients, patients with non-TB lung disease, and HIV+TB- patients. Combination of the 3 peptides provided sensitivity and specificity>90%. While the final fully optimized lateral flow POC test for TB is under development, these preliminary results demonstrate that an antibody-detection based rapid POC lateral flow test based on select combinations of immunodominant M. tb-specific epitopes may potentially replace microscopy for TB diagnosis in TB-endemic settings. PMID:25247820

Effect of High-Frequency Oscillations on Cough Peak Flows Generated by Mechanical In-Exsufflation in Medically Stable Subjects With Amyotrophic Lateral Sclerosis.

PubMed

Sancho, Jesús; Bures, Enric; de La Asunción, Saray; Servera, Emilio

2016-08-01

Mechanically assisted coughing with mechanical in-exsufflation (MI-E) is recommended for noninvasive management of respiratory secretions in amyotrophic lateral sclerosis (ALS). To improve the effectiveness of the technique, a new device combining MI-E with high-frequency oscillations (HFO) has been developed. This work aimed to assess the effect of HFO on the cough peak flow generated by MI-E in medically stable subjects with ALS. This was a prospective study that included subjects with ALS in a medically stable condition. Cough peak flow generated by MI-E was measured in 4 situations: without HFO, with HFO during insufflation, with HFO during exsufflation, and with HFO in both cycles. The parameters used were: insufflation pressure of +40 cm H2O, exsufflation pressure of -40 cm H2O, insufflation time 2 s, exsufflation time 3 s, amplitude of oscillations 10 cm H2O, and frequency of oscillations 15 Hz. Forty-seven subjects with ALS were included: 66% males, 68.2 ± 9.2 y, 40% with bulbar onset, FVC = 1.7 ± 1.1 L, percent-of-predicted FVC = 54.4 ± 26.6%, cough peak flow = 3.8 ± 2.2 L/s, PImax = -39.4 ± 26.4 cm H2O, revised ALS scale = 28.5 ± 9.3, Norris bulbar subscore = 26.1 ± 10.4. No statistical differences were found in cough peak flow generated by MI-E in the 4 situations (without HFO = 4.0 ± 1.2 L/s, with insufflation HFO = 3.9 ± 1.2 L/s, with exsufflation HFO = 4.1 ± 1.2 L/s, with in-exsufflation HFO = 3.9 ± 1.1 L/s). The addition of HFO to mechanically assisted coughing with MI-E does not have an effect on the cough peak flow of medically stable subjects with ALS. Copyright © 2016 by Daedalus Enterprises.

Fine sediment trapping in river lateral cavities

NASA Astrophysics Data System (ADS)

Juez, C.; Maechler, G.; Schleiss, A. J.; Franca, M. J.

2016-12-01

River restoration is nowadays a major issue in the field of hydraulics. The natural course and geometry of the rivers have been artificially changed by human activities for different purposes (land gaining, flood protection, agriculture). From a morphologic point of view, channelized rivers often display a straight path and monotonous river banks. This is in contradiction with natural morphology, where a high diversity can be found across the channel path (meanders) and the banks (pools, riffles). One way to restore rivers consist of transforming the artificial banks by adding macro-roughness elements in the lateral river banks (also called cavities and lateral embayments). The creation of irregularities on the banks causes new flow patterns that diversify the river habitat. However, these lateral cavities may be also responsible of the change of the river morphology, since they may trap the fine sediments travelling within the water. This is particularly important in glacier-fed streams such as the upper Rhone River in Switzerland. These are charged with fine sediments resulting from the erosion of the underlying glaciers bottom. The creation of lateral cavities may affect the sediment and morphological equilibrium of the river since these may trap sediments. This work aims to study the influence of the lateral cavities on the transport of fine sediments in the main channel. A set of laboratory experiments were done which covered a wide range of rectangular cavity configurations. Key parameters such as the flow discharge, the aspect ratio of the cavities and the initial sediment concentration were tested. Surface PIV, sediment samples and turbidity temporal records were collected during the experiments. The trapping efficiency of the cavities and the associated flow patterns were analyzed. The resulting conclusions provide a useful information for the future design of river restoration projects.

[Effect of mental arithmetic and verbal fluency on blood flow velocity in the middle cerebral arteries].

PubMed

Amrein, Ilona; Pálvölgyi, László; Debreczeni, Róbert; Kamondi, Anita; Szirmai, Imre

2004-01-20

Using transcranial Doppler sonography (TCD), changes in blood flow velocity (BFV) can be measured in the Medial Cerebral Artery (MCA) during cognitive effort. Our goal was to define the time-course and laterality of BFV in healthy volunteers during arithmetic and verbal fluency tasks according to handedness. Twelve subjects (8 right-handed, 4 left-handed) were assessed. The TCD registered BFV in both MCA simultaneously. Heart rate was also recorded using TCD. Finally we included a 16-channel EEG. BFV laterality index (LI) was calculated. Participants were asked to count silently and generate words beginning with a specified letter. To estimate hemispheric differences in BFV, two-tailed Wilcoxon tests were utilized along with correlational analyses. During cognitive effort the BFV changed in a tri-phasic manner in all participants. A 6-8% elevation of BFV was observed in MCAs without latency at the time of the evoking signal. Laterality of BFV developed after 5-13 seconds during cognitive effort in right-, and several seconds later in left-handed subjects. During tasks the BFV increased in the dominant hemisphere up to 2.6-4.7% compared to the subdominant one. We also calculated the LI. During the verbal task the LI agreed with the handedness in 9 out of 12 subjects. During the mental arithmetic task, agreement was found in 6 out of 12 subjects. According to LI results we found a discrepancy between verbal and arithmetic tests in 3 out of 12 subjects. Cognitive effort elicites significant bilateral BFV increases in the MCAs, which suggests fast neurogenic regulation. The course of BFV during mental arithmetic proved to be different from course BFV assessed during the word fluency task. Based on the laterality of the BFV, the word-generation task was more sensitive in determining the dominant hemisphere when compared to the mental arithmetic task. The use of LI may help to estimate hemispheric functions even in pathologic circumstances.

Image-based modelling of lateral magma flow: the Basement Sill, Antarctica

PubMed Central

Mirhadizadeh, Seyed

2017-01-01

The McMurdo Dry Valleys magmatic system, Antarctica, provides a world-class example of pervasive lateral magma flow on a continental scale. The lowermost intrusion (Basement Sill) offers detailed sections through the now frozen particle microstructure of a congested magma slurry. We simulated the flow regime in two and three dimensions using numerical models built on a finite-element mesh derived from field data. The model captures the flow behaviour of the Basement Sill magma over a viscosity range of 1–104 Pa s where the higher end (greater than or equal to 102 Pa s) corresponds to a magmatic slurry with crystal fractions varying between 30 and 70%. A novel feature of the model is the discovery of transient, low viscosity (less than or equal to 50 Pa s) high Reynolds number eddies formed along undulating contacts at the floor and roof of the intrusion. Numerical tracing of particle orbits implies crystals trapped in eddies segregate according to their mass density. Recovered shear strain rates (10−3–10−5 s−1) at viscosities equating to high particle concentrations (around more than 40%) in the Sill interior point to shear-thinning as an explanation for some types of magmatic layering there. Model transport rates for the Sill magmas imply a maximum emplacement time of ca 105 years, consistent with geochemical evidence for long-range lateral flow. It is a theoretically possibility that fast-flowing magma on a continental scale will be susceptible to planetary-scale rotational forces. PMID:28573002

Image-based modelling of lateral magma flow: the Basement Sill, Antarctica.

PubMed

Petford, Nick; Mirhadizadeh, Seyed

2017-05-01

The McMurdo Dry Valleys magmatic system, Antarctica, provides a world-class example of pervasive lateral magma flow on a continental scale. The lowermost intrusion (Basement Sill) offers detailed sections through the now frozen particle microstructure of a congested magma slurry. We simulated the flow regime in two and three dimensions using numerical models built on a finite-element mesh derived from field data. The model captures the flow behaviour of the Basement Sill magma over a viscosity range of 1-10 4  Pa s where the higher end (greater than or equal to 10 2  Pa s) corresponds to a magmatic slurry with crystal fractions varying between 30 and 70%. A novel feature of the model is the discovery of transient, low viscosity (less than or equal to 50 Pa s) high Reynolds number eddies formed along undulating contacts at the floor and roof of the intrusion. Numerical tracing of particle orbits implies crystals trapped in eddies segregate according to their mass density. Recovered shear strain rates (10 -3 -10 -5  s -1 ) at viscosities equating to high particle concentrations (around more than 40%) in the Sill interior point to shear-thinning as an explanation for some types of magmatic layering there. Model transport rates for the Sill magmas imply a maximum emplacement time of ca 10 5 years, consistent with geochemical evidence for long-range lateral flow. It is a theoretically possibility that fast-flowing magma on a continental scale will be susceptible to planetary-scale rotational forces.

Windflow circulation patterns in a coastal dune blowout, south coast of Lake Michigan

USGS Publications Warehouse

Fraser, G.S.; Bennett, S.W.; Olyphant, G.A.; Bauch, N.J.; Ferguson, V.; Gellasch, C.A.; Millard, C.L.; Mueller, B.; O'Malley, P. J.; Way, J.N.; Woodfield, M.C.

1998-01-01

The windflow patterns in a large active blowout in a coastal dune on the southern shore of Lake Michigan were intensively monitored during a two-day period when the predominant winds shifted from onshore (Day 1) to offshore (Day 2). The wind data were used in conjunction with mapped geomorphic features and sedimentologic characteristics to infer the following aspects of blowout evolution: (1) Prevailing winds are transformed considerably once they enter the blowout. Flow separation occurs when offshore winds enter the blowout over the steep back wall. Separated flows may, in turn, induce countercurrent flows within the trough. Flow expansion and deceleration occur when onshore winds enter over gently sloping walls at the front of the blowout. (2) Maximum erosion occurs along the deflationary floor near the entrance to the blowout, and lateral extensional lobes are also expanding the blowout to the east. Sand avalanches down the eastern and western lateral walls toward the deflationary floor where it is moved toward the rear of the blowout and up the ramp at the south end. Sand leaves the blowout as a series of depositional lobes prograding out onto the surface of the host dune along the south and east walls. (3) Vegetation prevents expansion of the blowout in certain directions and impediments to flow, such as slump blocks, alter circulation patterns and sand transport paths. (4) Prevailing onshore winds deflate the floor and promote eastward expansion of lateral erosional lobes, whereas strong flows from the southwest apparently are the main cause of transport up the transportational ramp and over the south wall of the blowout.

Functional expression of P2X4 receptor in capillary endothelial cells of the cochlear spiral ligament and its role in regulating the capillary diameter.

PubMed

Wu, T; Dai, M; Shi, X R; Jiang, Z G; Nuttall, A L

2011-07-01

The cochlear lateral wall generates the endocochlear potential (EP), which creates a driving force for the hair cell transduction current and is essential for normal hearing. Blood flow at the cochlear lateral wall is critically important for maintaining the EP. The vulnerability of the EP to hypoxia suggests that the blood flow in the cochlear lateral wall is dynamically and precisely regulated to meet the changing metabolic needs of the cochlear lateral wall. It has been reported that ATP, an important extracellular signaling molecule, plays an essential role in regulating cochlear blood flow. However, the cellular mechanism underlying ATP-induced regional blood flow changes has not been investigated. In the current study, we demonstrate that 1) the P2X4 receptor is expressed in endothelial cells (ECs) of spiral ligament (SL) capillaries. 2) ATP elicits a characteristic current through P2X4 on ECs in a dose-dependent manner (EC(50) = 0.16 mM). The ATP current has a reversal potential at ∼0 mV; is inhibited by 5-(3-bromophenyl)-1,3-dihydro-2H-benzofuro[3,2-e]-1,4-diazepin-2-one (5-BDBD), LaCl(3), pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) tetrasodium salt hydrate (PPADS), and extracellular acidosis; and is less sensitive to α,β-methyleneadenosine 5'-triphosphate (α,β-MeATP) and 2'- and 3'-O-(4-benzoyl-benzoyl) adenosine 5'-triphosphate (BzATP). 3) ATP elicits a transient increase of intracellular Ca(2+) in ECs. 4) In accordance with the above in vitro findings, perilymphatic ATP (1 mM) caused dilation in SL capillaries in vivo by 11.5%. N(ω)-nitro-l-arginine methyl ester hydrochloride (l-NAME), a nonselective inhibitor of nitric oxide synthase, or 5-BDBD, the specific P2X4 inhibitor, significantly blocked the dilation. These findings support our hypothesis that extracellular ATP regulates cochlear lateral blood flow through P2X4 activation in ECs.

Development of field-applicable tests for rapid and sensitive detection of Candidatus Phytoplasma oryzae.

PubMed

Wambua, Lillian; Schneider, Bernd; Okwaro, Allan; Wanga, Joseph Odhiambo; Imali, Olive; Wambua, Peninah Nduku; Agutu, Lavender; Olds, Cassandra; Jones, Chris Stephen; Masiga, Daniel; Midega, Charles; Khan, Zeyaur; Jores, Joerg; Fischer, Anne

2017-10-01

Napier grass Stunt Disease (NSD) is a severe disease of Napier grass (Pennisetum purpureum) in Eastern Africa, caused by the leafhopper-transmitted bacterium Candidatus Phytoplasma oryzae. The pathogen severely impairs the growth of Napier grass, the major fodder for dairy cattle in Eastern Africa. NSD is associated with biomass losses of up to 70% of infected plants. Diagnosis of NSD is done by nested PCR targeting the phytoplasma DNA, which is difficult to perform in developing countries with little infrastructure. We report the development of an easy to use, rapid, sensitive and specific molecular assay for field diagnosis of NSD. The procedure is based on recombinase polymerase amplification and targets the imp gene encoding a pathogen-specific immunodominant membrane protein. Therefore we followed a two-step process. First we developed an isothermal DNA amplification method for real time fluorescence application and then transferred this assay to a lateral flow format. The limit of detection for both procedures was estimated to be 10 organisms. We simplified the template preparation procedure by using freshly squeezed phloem sap from Napier grass. Additionally, we developed a laboratory serological assay with the potential to be converted to a lateral flow assay. Two murine monoclonal antibodies with high affinity and specificity to the immunodominant membrane protein IMP of Candidatus Phytoplasma oryzae were generated. Both antibodies specifically reacted with the denatured or native 17 kDa IMP protein. In dot blot experiments of extracts from infected plant, phytoplasmas were detected in as little as 12,5 μg of fresh plant material. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

In vivo lateral blood flow velocity measurement using speckle size estimation.

PubMed

Xu, Tiantian; Hozan, Mohsen; Bashford, Gregory R

2014-05-01

In previous studies, we proposed blood measurement using speckle size estimation, which estimates the lateral component of blood flow within a single image frame based on the observation that the speckle pattern corresponding to blood reflectors (typically red blood cells) stretches (i.e., is "smeared") if blood flow is in the same direction as the electronically controlled transducer line selection in a 2-D image. In this observational study, the clinical viability of ultrasound blood flow velocity measurement using speckle size estimation was investigated and compared with that of conventional spectral Doppler of carotid artery blood flow data collected from human patients in vivo. Ten patients (six male, four female) were recruited. Right carotid artery blood flow data were collected in an interleaved fashion (alternating Doppler and B-mode A-lines) with an Antares Ultrasound Imaging System and transferred to a PC via the Axius Ultrasound Research Interface. The scanning velocity was 77 cm/s, and a 4-s interval of flow data were collected from each subject to cover three to five complete cardiac cycles. Conventional spectral Doppler data were collected simultaneously to compare with estimates made by speckle size estimation. The results indicate that the peak systolic velocities measured with the two methods are comparable (within ±10%) if the scan velocity is greater than or equal to the flow velocity. When scan velocity is slower than peak systolic velocity, the speckle stretch method asymptotes to the scan velocity. Thus, the speckle stretch method is able to accurately measure pure lateral flow, which conventional Doppler cannot do. In addition, an initial comparison of the speckle size estimation and color Doppler methods with respect to computational complexity and data acquisition time indicated potential time savings in blood flow velocity estimation using speckle size estimation. Further studies are needed for calculation of the speckle stretch method across a field of view and combination with an appropriate axial flow estimator. Copyright © 2014 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

High-resolution characterization of chemical heterogeneity in an alluvial aquifer

USGS Publications Warehouse

Schulmeister, M.K.; Healey, J.M.; McCall, G.W.; Birk, S.; Butler, J.J.

2002-01-01

The high-resolution capabilities of direct-push technology were exploited to develop new insights into the hydrochemistry at the margin of an alluvial aquifer. Hydrostratigraphic controls on groundwater flow and contaminant loading were revealed through the combined use of direct-push electrical conductivity (EC) logging and geochemical profiling. Vertical and lateral variations in groundwater chemistry were consistent with sedimentary features indicated by EC logs, and supported a conceptual model of recharge along the floodplain margin.

PrimaTB STAT-PAK Assay, a Novel, Rapid Lateral-Flow Test for Tuberculosis in Nonhuman Primates▿

PubMed Central

Lyashchenko, Konstantin P.; Greenwald, Rena; Esfandiari, Javan; Greenwald, David; Nacy, Carol A.; Gibson, Susan; Didier, Peter J.; Washington, Marc; Szczerba, Peter; Motzel, Sherri; Handt, Larry; Pollock, John M.; McNair, James; Andersen, Peter; Langermans, Jan A. M.; Verreck, Frank; Ervin, Sean; Ervin, Frank; McCombs, Candace

2007-01-01

Tuberculosis (TB) is the most important zoonotic bacterial disease in nonhuman primates (NHP). The current diagnostic method, the intradermal palpebral tuberculin test, has serious shortcomings. We characterized antibody responses in NHP against Mycobacterium tuberculosis to identify immunodominant antigens and develop a rapid serodiagnostic test for TB. A total of 422 NHP were evaluated, including 243 rhesus (Macaca mulatta), 46 cynomolgus (Macaca fascicularis), and 133 African green (Cercopithecus aethiops sabaeus) monkeys at five collaborative centers. Of those, 50 monkeys of the three species were experimentally inoculated with M. tuberculosis. Antibody responses were monitored every 2 to 4 weeks for up to 8 months postinfection by MultiAntigen Print ImmunoAssay with a panel of 12 recombinant antigens. All of the infected monkeys produced antibodies at various levels and with different antigen recognition patterns. ESAT-6 and MPB83 were the most frequently recognized proteins during infection. A combination of selected antigens which detected antibodies in all of the infected monkeys was designed to develop the PrimaTB STAT-PAK assay by lateral-flow technology. Serological evaluation demonstrated high diagnostic sensitivity (90%) and specificity (99%). The highest rate of TB detection was achieved when the skin test was combined with the PrimaTB STAT-PAK kit. This novel immunoassay provides a simple, rapid, and accurate test for TB in NHP. PMID:17652522

Development of real-time and lateral flow dipstick recombinase polymerase amplification assays for rapid detection of goatpox virus and sheeppox virus.

PubMed

Yang, Yang; Qin, Xiaodong; Zhang, Xiangle; Zhao, Zhixun; Zhang, Wei; Zhu, Xueliang; Cong, Guozheng; Li, Yanmin; Zhang, Zhidong

2017-07-17

Goatpox virus (GTPV) and sheeppox virus (SPPV), which belong to the Capripoxvirus (CaPV), are economically important pathogens of small ruminants. Therefore, a sensitive, specific and rapid diagnostic assay for detection of GTPV and SPPV is necessary to accurately and promptly control these diseases. Recombinase polymerase amplification (RPA) assays combined with a real-time fluorescent detection (real-time RPA assay) and lateral flow dipstick (RPA LFD assay) were developed targeting the CaPV G-protein-coupled chemokine receptor (GPCR) gene, respectively. The sensitivity of both CaPV real-time RPA assay and CaPV RPA LFD assay were 3 × 10 2 copies per reaction within 20 min at 38 °C. Both assays were highly specific for CaPV, with no cross-reactions with peste des petits ruminants virus, foot-and-mouth disease virus and Orf virus. The evaluation of the performance of these two assays with clinical sample (n = 107) showed that the CaPV real-time RPA assay and CaPV RPA LFD assay were able to specially detect SPPV or GTPV present in samples of ovine in liver, lung, kidney, spleen, skin and blood. This study provided a highly time-efficient and simple alternative for rapid detection of GTPV and SPPV.

Impeller leakage flow modeling for mechanical vibration control

NASA Technical Reports Server (NTRS)

Palazzolo, Alan B.

1996-01-01

HPOTP and HPFTP vibration test results have exhibited transient and steady characteristics which may be due to impeller leakage path (ILP) related forces. For example, an axial shift in the rotor could suddenly change the ILP clearances and lengths yielding dynamic coefficient and subsequent vibration changes. ILP models are more complicated than conventional-single component-annular seal models due to their radial flow component (coriolis and centrifugal acceleration), complex geometry (axial/radial clearance coupling), internal boundary (transition) flow conditions between mechanical components along the ILP and longer length, requiring moment as well as force coefficients. Flow coupling between mechanical components results from mass and energy conservation applied at their interfaces. Typical components along the ILP include an inlet seal, curved shroud, and an exit seal, which may be a stepped labyrinth type. Von Pragenau (MSFC) has modeled labyrinth seals as a series of plain annular seals for leakage and dynamic coefficient prediction. These multi-tooth components increase the total number of 'flow coupled' components in the ILP. Childs developed an analysis for an ILP consisting of a single, constant clearance shroud with an exit seal represented by a lumped flow-loss coefficient. This same geometry was later extended to include compressible flow. The objective of the current work is to: supply ILP leakage-force impedance-dynamic coefficient modeling software to MSFC engineers, base on incompressible/compressible bulk flow theory; design the software to model a generic geometry ILP described by a series of components lying along an arbitrarily directed path; validate the software by comparison to available test data, CFD and bulk models; and develop a hybrid CFD-bulk flow model of an ILP to improve modeling accuracy within practical run time constraints.

Simulation of hydrodynamics, temperature, and dissolved oxygen in Table Rock Lake, Missouri, 1996-1997

USGS Publications Warehouse

Green, W. Reed; Galloway, Joel M.; Richards, Joseph M.; Wesolowski, Edwin A.

2003-01-01

Outflow from Table Rock Lake and other White River reservoirs support a cold-water trout fishery of substantial economic yield in south-central Missouri and north-central Arkansas. The Missouri Department of Conservation has requested an increase in existing minimum flows through the Table Rock Lake Dam from the U.S. Army Corps of Engineers to increase the quality of fishable waters downstream in Lake Taneycomo. Information is needed to assess the effect of increased minimum flows on temperature and dissolved- oxygen concentrations of reservoir water and the outflow. A two-dimensional, laterally averaged, hydrodynamic, temperature, and dissolved-oxygen model, CE-QUAL-W2, was developed and calibrated for Table Rock Lake, located in Missouri, north of the Arkansas-Missouri State line. The model simulates water-surface elevation, heat transport, and dissolved-oxygen dynamics. The model was developed to assess the effects of proposed increases in minimum flow from about 4.4 cubic meters per second (the existing minimum flow) to 11.3 cubic meters per second (the increased minimum flow). Simulations included assessing the effect of (1) increased minimum flows and (2) increased minimum flows with increased water-surface elevations in Table Rock Lake, on outflow temperatures and dissolved-oxygen concentrations. In both minimum flow scenarios, water temperature appeared to stay the same or increase slightly (less than 0.37 ?C) and dissolved oxygen appeared to decrease slightly (less than 0.78 mg/L) in the outflow during the thermal stratification season. However, differences between the minimum flow scenarios for water temperature and dissolved- oxygen concentration and the calibrated model were similar to the differences between measured and simulated water-column profile values.

Difference in vascular patterns between transosseous-equivalent and transosseous rotator cuff repair.

PubMed

Urita, Atsushi; Funakoshi, Tadanao; Horie, Tatsunori; Nishida, Mutsumi; Iwasaki, Norimasa

2017-01-01

Vascularity is the important factor of biologic healing of the repaired tissue. The purpose of this study was to clarify sequential vascular patterns of repaired rotator cuff by suture techniques. We randomized 21 shoulders in 20 patients undergoing arthroscopic rotator cuff repair into 2 groups: transosseous-equivalent repair (TOE group, n = 10) and transosseous repair (TO group, n = 11). Blood flow in 4 regions inside the cuff (lateral articular, lateral bursal, medial articular, and medial bursal), in the knotless suture anchor in the TOE group, and in the bone tunnel in the TO group was measured using contrast-enhanced ultrasound at 1 month, 2 months, 3 months, and 6 months postoperatively. The sequential vascular pattern inside the repaired rotator cuff was different between groups. The blood flow in the lateral articular area at 1 month, 2 months, and 3 months (P = .002, .005, and .025) and that in the lateral bursal area at 2 months (P = .031) in the TO group were significantly greater than those in the TOE group postoperatively. Blood flow was significantly greater for the bone tunnels in the TO group than for the knotless suture anchor in the TOE group at 1 month and 2 months postoperatively (P = .041 and .009). This study clarified that the sequential vascular pattern inside the repaired rotator cuff depends on the suture technique used. Bone tunnels through the footprint may contribute to biologic healing by increasing blood flow in the repaired rotator cuff. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Integration of geology, geostatistics, well logs and pressure data to model a heterogeneous supergiant field in Iran

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samimi, B.; Bagherpour, H.; Nioc, A.

1995-08-01

The geological reservoir study of the supergiant Ahwaz field significantly improved the history matching process in many aspects, particularly the development of a geostatistical model which allowed a sound basis for changes and by delivering much needed accurate estimates of grid block vertical permeabilities. The geostatistical reservoir evaluation was facilitated by using the Heresim package and litho-stratigraphic zonations for the entire field. For each of the geological zones, 3-dimensional electrolithofacies and petrophysical property distributions (realizations) were treated which captured the heterogeneities which significantly affected fluid flow. However, as this level of heterogeneity was at a significantly smaller scale than themore » flow simulation grid blocks, a scaling up effort was needed to derive the effective flow properties of the blocks (porosity, horizontal and vertical permeability, and water saturation). The properties relating to the static reservoir description were accurately derived by using stream tube techniques developed in-house whereas, the relative permeabilities of the grid block were derived by dynamic pseudo relative permeability techniques. The prediction of vertical and lateral communication and water encroachment was facilitated by a close integration of pressure, saturation data, geostatistical modelling and sedimentological studies of the depositional environments and paleocurrents. The nature of reservoir barriers and baffles varied both vertically and laterally in this heterogeneous reservoir. Maps showing differences in pressure between zones after years of production served as a guide to integrating the static geological studies to the dynamic behaviour of each of the 16 reservoir zones. The use of deep wells being drilled to a deeper reservoir provided data to better understand the sweep efficiency and the continuity of barriers and baffles.« less

Seismic responses and controlling factors of Miocene deepwater gravity-flow deposits in Block A, Lower Congo Basin

NASA Astrophysics Data System (ADS)

Wang, Linlin; Wang, Zhenqi; Yu, Shui; Ngia, Ngong Roger

2016-08-01

The Miocene deepwater gravity-flow sedimentary system in Block A of the southwestern part of the Lower Congo Basin was identified and interpreted using high-resolution 3-D seismic, drilling and logging data to reveal development characteristics and main controlling factors. Five types of deepwater gravity-flow sedimentary units have been identified in the Miocene section of Block A, including mass transport, deepwater channel, levee, abandoned channel and sedimentary lobe deposits. Each type of sedimentary unit has distinct external features, internal structures and lateral characteristics in seismic profiles. Mass transport deposits (MTDs) in particular correspond to chaotic low-amplitude reflections in contact with mutants on both sides. The cross section of deepwater channel deposits in the seismic profile is in U- or V-shape. The channel deposits change in ascending order from low-amplitude, poor-continuity, chaotic filling reflections at the bottom, to high-amplitude, moderate to poor continuity, chaotic or sub-parallel reflections in the middle section and to moderate-weak amplitude, good continuity, parallel or sub-parallel reflections in the upper section. The sedimentary lobes are laterally lobate, which corresponds to high-amplitude, good-continuity, moundy reflection signatures in the seismic profile. Due to sediment flux, faults, and inherited terrain, few mass transport deposits occur in the northeastern part of the study area. The front of MTDs is mainly composed of channel-levee complex deposits, while abandoned-channel and lobe-deposits are usually developed in high-curvature channel sections and the channel terminals, respectively. The distribution of deepwater channel, levee, abandoned channel and sedimentary lobe deposits is predominantly controlled by relative sea level fluctuations and to a lesser extent by tectonism and inherited terrain.

Front propagation in a regular vortex lattice: Dependence on the vortex structure.

PubMed

Beauvier, E; Bodea, S; Pocheau, A

2017-11-01

We investigate the dependence on the vortex structure of the propagation of fronts in stirred flows. For this, we consider a regular set of vortices whose structure is changed by varying both their boundary conditions and their aspect ratios. These configurations are investigated experimentally in autocatalytic solutions stirred by electroconvective flows and numerically from kinematic simulations based on the determination of the dominant Fourier mode of the vortex stream function in each of them. For free lateral boundary conditions, i.e., in an extended vortex lattice, it is found that both the flow structure and the front propagation negligibly depend on vortex aspect ratios. For rigid lateral boundary conditions, i.e., in a vortex chain, vortices involve a slight dependence on their aspect ratios which surprisingly yields a noticeable decrease of the enhancement of front velocity by flow advection. These different behaviors reveal a sensitivity of the mean front velocity on the flow subscales. It emphasizes the intrinsic multiscale nature of front propagation in stirred flows and the need to take into account not only the intensity of vortex flows but also their inner structure to determine front propagation at a large scale. Differences between experiments and simulations suggest the occurrence of secondary flows in vortex chains at large velocity and large aspect ratios.

Lateral jet injection into typical combustor flowfields

NASA Technical Reports Server (NTRS)

Lilley, D. G.

1986-01-01

The experimental problem of lateral jet injection into typical flow fields in the absence of combustion was studied. All flow fields being investigated have no expansion of the crossflow (the test section to swirler diameter ratio D/d = 1), after its passage through an optional swirler (with swirl vane angle phi = 0 (swirler removed), 45, and 70 degree). The lateral jet(s) is(are) located one test-section diameter downstream of the test-section inlet (x/D = 1). The lateral jets have round-sectioned nozzles, each of which has an area of 1/100th of the cross sectional area of the crossflow (A sub j/A sub c = 1/100). Jet-to-crossflow velocity ratios of R = v sub j/u sub o = 2, 4, and 6 were investigated. Helium-bubble low visualization, five-hole pitot probe time-mean velocity measurements, and single-wire time-mean velocity and normal and shear stress turbulence data were obtained in the research program.

7. 'FLOW IN CANAL NO. 1, A JOINTLY USED CANAL, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. 'FLOW IN CANAL NO. 1, A JOINTLY USED CANAL, ON MAY 22 WHEN 210 SECOND FEET OF WATER WAS FLOWING. THIS WAS LATER INCREASED TO 240 SECOND FEET FOR A NUMBER OF DAYS TO SATISFY THE DEMANDS OF THE DRY GULCH COMPANY.' 1925 - Irrigation Canals in the Uinta Basin, Duchesne, Duchesne County, UT

Comparison of Lateral Flow Assay, Kidney Inhibition Swab, and Liquid Chromatography-Tandem Mass Spectrometry for the Detection of Penicillin G Residues in Sow Urine.

PubMed

Shelver, Weilin L; Chakrabarty, Shubhashis; Smith, David J

2017-03-01

Sows (n = 126) were administered penicillin G; urine, collected at slaughter, was screened by kidney inhibition swab (KIS; 4 h testing time) and then stored at -80 °C (∼1200 days) until analysis by lateral flow assay (LF, ∼5 min testing time) and tandem quadrupole LC-MS/MS (TQ) analysis. The stability of penicillin in urine during storage was verified using TQ analyses. Quantitative results were well-correlated (R 2 = 0.98) with only a ∼10% decrease in penicillin concentration during the 3-year storage period. KIS retesting of stored samples returned results consistent with the original analyses. Lateral flow assay results were highly correlated with the KIS and TQ results. A KIS positive sample, which was not confirmed by TQ or LF, was assayed by Triple-TOF LC-MS to determine the cause of the apparent false positive. This study suggests LF can be used to quickly and efficiently screen for penicillin G residues before slaughter.

Design and performance analysis of an aero-maneuvering orbital-transfer vehicle concept

NASA Technical Reports Server (NTRS)

Menees, G. P.

1985-01-01

Systems requirements for design-optimized, lateral-turn performance were determined for reusable, space-based applications and low-Earth orbits involving large multiple plane-inclination changes. The aerothermodynamic analysis is the most advanced available for rarefield-hypersonic flow over lifting surfaces at incidence. The effects of leading-edge bluntness, low-density viscous phenomena, and finite-rate flow-field chemistry and surface catalysis are accounted for. The predicted aerothermal heating characteristics are correlated with thermal-control and flight-performance capabilities. The mission payload capacity for delivery, retrieval, and combined operations was determined for round-trip sorties extending to polar orbits. Recommendations are given for future design refinements. The results help to identify technology issues required to develop prototype operational vehicles.

Rapid fabrication of pressure-driven open-channel microfluidic devices in omniphobic R(F) paper.

PubMed

Glavan, Ana C; Martinez, Ramses V; Maxwell, E Jane; Subramaniam, Anand Bala; Nunes, Rui M D; Soh, Siowling; Whitesides, George M

2013-08-07

This paper describes the fabrication of pressure-driven, open-channel microfluidic systems with lateral dimensions of 45-300 microns carved in omniphobic paper using a craft-cutting tool. Vapor phase silanization with a fluorinated alkyltrichlorosilane renders paper omniphobic, but preserves its high gas permeability and mechanical properties. When sealed with tape, the carved channels form conduits capable of guiding liquid transport in the low-Reynolds number regime (i.e. laminar flow). These devices are compatible with complex fluids such as droplets of water in oil. The combination of omniphobic paper and a craft cutter enables the development of new types of valves and switches, such as "fold valves" and "porous switches," which provide new methods to control fluid flow.

Homolateral ataxia and crural paresis: a crossed cerebral-cerebellar diaschisis.

PubMed Central

Giroud, M; Creisson, E; Fayolle, H; Gras, P; Vion, P; Brunotte, F; Dumas, R

1994-01-01

A patient developed weakness of the right leg and homolateral ataxia of the arm, caused by a subcortical infarct in the area supplied by the anterior cerebral artery in the left paracentral region, demonstrated by CT and MRI. Cerebral blood flow studied by technetium-labelled hexamethyl-propylene-amine oxime using single photon emission computed tomography showed decreased blood flow in the left lateral frontal cortex and in the right cerebellar hemisphere ("crossed cerebral-cerebellar diaschisis"). The homolateral ataxia of the arm may be caused by decreased function of the right cerebellar hemisphere, because of a lesion of the corticopontine-cerebellar tracts, whereas crural hemiparesis is caused by a lesion of the upper part of the corona radiata. Images PMID:8126511

Lateral blasts at Mount St. Helens and hazard zonation

USGS Publications Warehouse

Crandell, D.R.; Hoblitt, R.P.

1986-01-01

Lateral blasts at andesitic and dacitic volcanoes can produce a variety of direct hazards, including ballistic projectiles which can be thrown to distances of at least 10 km and pyroclastic density flows which can travel at high speed to distances of more than 30 km. Indirect effect that may accompany such explosions include wind-borne ash, pyroclastic flows formed by the remobilization of rock debris thrown onto sloping ground, and lahars. Two lateral blasts occurred at a lava dome on the north flank of Mount St. Helens about 1200 years ago; the more energetic of these threw rock debris northeastward across a sector of about 30?? to a distance of at least 10 km. The ballistic debris fell onto an area estimated to be 50 km2, and wind-transported ash and lapilli derived from the lateral-blast cloud fell on an additional lobate area of at least 200 km2. In contrast, the vastly larger lateral blast of May 18, 1980, created a devastating pyroclastic density flow that covered a sector of as much as 180??, reached a maximum distance of 28 km, and within a few minutes directly affected an area of about 550 km2. The May 18 lateral blast resulted from the sudden, landslide-induced depressurization of a dacite cryptodome and the hydrothermal system that surrounded it within the volcano. We propose that lateral-blast hazard assessments for lava domes include an adjoining hazard zone with a radius of at least 10 km. Although a lateral blast can occur on any side of a dome, the sector directly affected by any one blast probably will be less than 180??. Nevertheless, a circular hazard zone centered on the dome is suggested because of the difficulty of predicting the direction of a lateral blast. For the purpose of long-term land-use planning, a hazard assessment for lateral blasts caused by explosions of magma bodies or pressurized hydrothermal systems within a symmetrical volcano could designate a circular potential hazard area with a radius of 35 km centered on the volcano. For short-term hazard assessments, if seismicity and deformation indicate that magma is moving toward the flank of a volcano, it should be recognized that a landslide could lead to the sudden unloading of a magmatic or hydrothermal system and thereby cause a catastrophic lateral blast. A hazard assessment should assume that a lateral blast could directly affect an area at least 180?? wide to a distance of 35 km from the site of the explosion, irrespective of topography. ?? 1986 Springer-Verlag.

Preferential flow, diffuse flow, and perching in an interbedded fractured-rock unsaturated zone

NASA Astrophysics Data System (ADS)

Nimmo, John R.; Creasey, Kaitlyn M.; Perkins, Kim S.; Mirus, Benjamin B.

2017-03-01

Layers of strong geologic contrast within the unsaturated zone can control recharge and contaminant transport to underlying aquifers. Slow diffuse flow in certain geologic layers, and rapid preferential flow in others, complicates the prediction of vertical and lateral fluxes. A simple model is presented, designed to use limited geological site information to predict these critical subsurface processes in response to a sustained infiltration source. The model is developed and tested using site-specific information from the Idaho National Laboratory in the Eastern Snake River Plain (ESRP), USA, where there are natural and anthropogenic sources of high-volume infiltration from floods, spills, leaks, wastewater disposal, retention ponds, and hydrologic field experiments. The thick unsaturated zone overlying the ESRP aquifer is a good example of a sharply stratified unsaturated zone. Sedimentary interbeds are interspersed between massive and fractured basalt units. The combination of surficial sediments, basalts, and interbeds determines the water fluxes through the variably saturated subsurface. Interbeds are generally less conductive, sometimes causing perched water to collect above them. The model successfully predicts the volume and extent of perching and approximates vertical travel times during events that generate high fluxes from the land surface. These developments are applicable to sites having a thick, geologically complex unsaturated zone of substantial thickness in which preferential and diffuse flow, and perching of percolated water, are important to contaminant transport or aquifer recharge.

Preferential flow, diffuse flow, and perching in an interbedded fractured-rock unsaturated zone

USGS Publications Warehouse

Nimmo, John R.; Creasey, Kaitlyn M; Perkins, Kimberlie; Mirus, Benjamin B.

2017-01-01

Layers of strong geologic contrast within the unsaturated zone can control recharge and contaminant transport to underlying aquifers. Slow diffuse flow in certain geologic layers, and rapid preferential flow in others, complicates the prediction of vertical and lateral fluxes. A simple model is presented, designed to use limited geological site information to predict these critical subsurface processes in response to a sustained infiltration source. The model is developed and tested using site-specific information from the Idaho National Laboratory in the Eastern Snake River Plain (ESRP), USA, where there are natural and anthropogenic sources of high-volume infiltration from floods, spills, leaks, wastewater disposal, retention ponds, and hydrologic field experiments. The thick unsaturated zone overlying the ESRP aquifer is a good example of a sharply stratified unsaturated zone. Sedimentary interbeds are interspersed between massive and fractured basalt units. The combination of surficial sediments, basalts, and interbeds determines the water fluxes through the variably saturated subsurface. Interbeds are generally less conductive, sometimes causing perched water to collect above them. The model successfully predicts the volume and extent of perching and approximates vertical travel times during events that generate high fluxes from the land surface. These developments are applicable to sites having a thick, geologically complex unsaturated zone of substantial thickness in which preferential and diffuse flow, and perching of percolated water, are important to contaminant transport or aquifer recharge.

Role of surface and subsurface lateral water flows on summer precipitation in a complex terrain region: A WRF-Hydro case-study for Southern Germany

NASA Astrophysics Data System (ADS)

Rummler, Thomas; Arnault, Joel; Gochis, David; Kunstmann, Harald

2017-04-01

Recent developments in hydrometeorological modeling aim towards more sophisticated treatment of terrestrial hydrologic processes. The standard version of the Weather Research and Forecasting (WRF) model describes terrestrial water transport as a purely vertical process. The hydrologically enhanced version of WRF, namely WRF-Hydro, does account for lateral terrestrial water flows, which allows for a more comprehensive process description of the interdependencies between water- and energy fluxes at the land-atmosphere interface. In this study, WRF and WRF-Hydro are applied to the Bavarian Alpine region in southern Germany, a complex terrain landscape in a relatively humid, mid-latitude climate. Simulation results are validated with gridded and station observation of precipitation, temperature and river discharge. Differences between WRF and WRF-Hydro results are investigated with a joint atmospheric-terrestrial water budget analysis. Changes in the partitioning in (near-) surface runoff and percolation are prominent. However, values for evapotranspiration ET feature only marginal variations, suggesting that soil moisture content is not a limiting factor of ET in this specific region. Simulated precipitation fields during isolated summertime events still show appreciable differences, while differences in large-scale, multi-day rainy periods are less substantial. These differences are mainly related to differences in the moisture in- and outflow terms of the atmospheric water budget induced by the surface and sub-surface lateral redistribution of soil moisture in WRF-Hydro.

Valley-scale morphology drives differences in fluvial sediment budgets and incision rates during contrasting flow regimes

NASA Astrophysics Data System (ADS)

Weber, M. D.; Pasternack, G. B.

2017-07-01

High-resolution topographic surveys using LiDAR and multibeam sonar can be used to characterize and quantify fluvial change. This study used repeat surveys to explore how topographic change, fluvial processes, sediment budgets, and aggradation and incision rates vary across spatial scales and across two contrasting decadal flow regimes in a regulated gravel/cobble river. A novel method for quantifying digital elevation model uncertainty was developed and applied to a topographic change detection analysis from 2006/2008 to 2014. During this period, which had four modest 3-5 year floods, most sediment was laterally redistributed through bank erosion and channel migration. Erosion primarily occurred in the floodplain (97,000 m3), terraces (80,000 m3), and lateral bars (58,000 m3); while deposition occurred in the adjacent pools (73,000 m3), fast glides (48,000 m3), and runs (36,000 m3). In contrast, significantly higher magnitude and longer duration floods from 1999 to 2006/2008 caused sediment to be displaced longitudinally, with the upstream reaches exporting sediment and the downstream reaches aggrading. The river maintained floodplain connectivity during both periods, despite different processes dominating the type of connectivity. Larger floods promoted overbank scour and avulsion, while smaller floods promoted bank erosion and lateral migration. This study explores and illustrates how the geomorphic response to contrasting flood regimes in a nonuniform river is highly dependent on which landforms are controlling hydraulics.

Tearing Instability of a Current Sheet Forming by Sheared Incompressible Flow

NASA Astrophysics Data System (ADS)

Tolman, Elizabeth; Loureiro, Nuno; Uzdensky, Dmitri

2017-10-01

Sweet-Parker current sheets are unstable to the tearing mode, suggesting they will not form in physical systems. Understanding magnetic reconnection thus requires study of the stability of a current sheet as it forms. Such formation can occur as a result of sheared, sub-Alfvénic incompressible flows into and along the sheet. This work presents an analysis of how tearing perturbations behave in a current sheet forming under the influence of such flows, beginning with a phase when the growth rate of the tearing mode is small and the behavior of perturbations is primarily governed by ideal MHD. Later, after the tearing growth rate becomes significant relative to the time scale of the driving flows, the flows cause a slight reduction in the tearing growth rate and wave vector of the dominant mode. Once the tearing mode enters the nonlinear regime, the flows accelerate the tearing growth slightly; during X-point collapse, the flows have negligible effect on the system behavior. This analysis allows greater understanding of reconnection in evolving systems and increases confidence in the application of tools developed in time-independent current sheets to changing current sheets. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship.

Flow Generated by a Partially Penetrating Well in a Leaky Two-Aquifer System with a Storative Semiconfining Layer

NASA Astrophysics Data System (ADS)

Sepulveda, N.; Rohrer, K.

2008-05-01

The permeability of the semiconfining layers of the highly productive Floridan Aquifer System may be large enough to invalidate the assumptions of the leaky aquifer theory. These layers are the intermediate confining and the middle semiconfining units. The analysis of aquifer-test data with analytical solutions of the ground-water flow equation developed with the approximation of a low hydraulic conductivity ratio between the semiconfining layer and the aquifer may lead to inaccurate hydraulic parameters. An analytical solution is presented here for the flow in a confined leaky aquifer, the overlying storative semiconfining layer, and the unconfined aquifer, generated by a partially penetrating well in a two-aquifer system, and allowing vertical and lateral flow components to occur in the semiconfining layer. The equations describing flow caused by a partially penetrating production well are solved analytically to provide a method to accurately determine the hydraulic parameters in the confined aquifer, semiconfining layer, and unconfined aquifer from aquifer-test data. Analysis of the drawdown data from an aquifer test performed in central Florida showed that the flow solution presented here for the semiconfining layer provides a better match and a more unique identification of the hydraulic parameters than an analytical solution that considers only vertical flow in the semiconfining layer.

Rapid runoff via shallow throughflow and deeper preferential flow in a boreal catchment underlain by frozen silt (Alaska, USA)

USGS Publications Warehouse

Koch, Joshua C.; Ewing, Stephanie A.; Striegl, Robert G.; McKnight, Diane M.

2013-01-01

In high-latitude catchments where permafrost is present, runoff dynamics are complicated by seasonal active-layer thaw, which may cause a change in the dominant flowpaths as water increasingly contacts mineral soils of low hydraulic conductivity. A 2-year study, conducted in an upland catchment in Alaska (USA) underlain by frozen, well-sorted eolian silt, examined changes in infiltration and runoff with thaw. It was hypothesized that rapid runoff would be maintained by flow through shallow soils during the early summer and deeper preferential flow later in the summer. Seasonal changes in soil moisture, infiltration, and runoff magnitude, location, and chemistry suggest that transport is rapid, even when soils are thawed to their maximum extent. Between June and September, a shift occurred in the location of runoff, consistent with subsurface preferential flow in steep and wet areas. Uranium isotopes suggest that late summer runoff erodes permafrost, indicating that substantial rapid flow may occur along the frozen boundary. Together, throughflow and deep preferential flow may limit upland boreal catchment water and solute storage, and subsequently biogeochemical cycling on seasonal to annual timescales. Deep preferential flow may be important for stream incision, network drainage development, and the release of ancient carbon to ecosystems

Finite element modeling of self-potential signals over conduits and fractures in covered karst terrain Peter Bumpus and Sarah Kruse

NASA Astrophysics Data System (ADS)

Bumpus, P. B.; Kruse, S. E.

2013-12-01

A year of continuous monitoring with two grids of 12-15 electrodes each measured self-potential (SP) over two small covered-karst conduits in Tampa, Florida. Positive and negative SP anomalies episodically manifested over conduits, suggesting that conduit flow is dynamic, not static. Various SP flow regimes in the conduits are postulated: flow in the conduit is faster than through surrounding surficial sediment, flow in the conduit is slower than through surrounding sediment, and conduit flow rates match those through the surrounding sediments. It is further postulated that conduits change permeability with inflow and washing out of sediment, especially associated with rain events. Numerical simulations of the postulated flow regimes were run with 2D simulations using the Comsol finite element modeling code. Simulations show that each regime produces different SP patterns. Models simulate the Tampa field setting in which a 1-2 meter-thick high permeability sand layer overlies a low-permeability clay-rich layer. A funnel-shaped conduit breaches both layers. In the models, when the permeability of the conduit sands is equal to surrounding surficial sands, a small (several mV) negative anomaly manifests locally at the conduit. This negative anomaly can be explained as the result of the depression of the SPS surface (the first sediment surface with a change in conductance or streaming potential coefficient) in the conduit. However a permeability difference of as little as 5 to 20 percent between conduit and background can cause an SP anomaly of tens to several hundred millivolts, either positive or negative. When the permeability is higher in the conduit than the surficial sands, lateral flow into the conduit within the sand layer and through the conduit to the underlying aquifer are both high, and the SP signal over the conduit is positive. This may contradict the concept exemplified in other studies that downward flow creates a negative anomaly. In our case the positive voltage is the result of high lateral flow toward a high flux conduit. As a result, the horizontal dimension of the conduit plays a role in whether a positive or negative anomaly is observed locally near the surface, depending on the degree to which the terminus of the inward lateral flow affects voltage over the conduit center. When the conduit has lower permeability than surrounding surficial sediment, models show that the SP anomaly is negative. In this case lateral flow is small to a low-flux conduit and there is little build-up of positive SP to overcome the negative potential associated with the SPS trough.

Influence of slip-surface geometry on earth-flow deformation, Montaguto earth flow, southern Italy

USGS Publications Warehouse

Guerriero, L.; Coe, Jeffrey A.; Revellio, P.; Grelle, G.; Pinto, F.; Guadagno, F.

2016-01-01

We investigated relations between slip-surface geometry and deformational structures and hydrologic features at the Montaguto earth flow in southern Italy between 1954 and 2010. We used 25 boreholes, 15 static cone-penetration tests, and 22 shallow-seismic profiles to define the geometry of basal- and lateral-slip surfaces; and 9 multitemporal maps to quantify the spatial and temporal distribution of normal faults, thrust faults, back-tilted surfaces, strike-slip faults, flank ridges, folds, ponds, and springs. We infer that the slip surface is a repeating series of steeply sloping surfaces (risers) and gently sloping surfaces (treads). Stretching of earth-flow material created normal faults at risers, and shortening of earth-flow material created thrust faults, back-tilted surfaces, and ponds at treads. Individual pairs of risers and treads formed quasi-discrete kinematic zones within the earth flow that operated in unison to transmit pulses of sediment along the length of the flow. The locations of strike-slip faults, flank ridges, and folds were not controlled by basal-slip surface topography but were instead dependent on earth-flow volume and lateral changes in the direction of the earth-flow travel path. The earth-flow travel path was strongly influenced by inactive earth-flow deposits and pre-earth-flow drainages whose positions were determined by tectonic structures. The implications of our results that may be applicable to other earth flows are that structures with strikes normal to the direction of earth-flow motion (e.g., normal faults and thrust faults) can be used as a guide to the geometry of basal-slip surfaces, but that depths to the slip surface (i.e., the thickness of an earth flow) will vary as sediment pulses are transmitted through a flow.

Development of quantitative radioactive methodologies on paper to determine important lateral-flow immunoassay parameters.

PubMed

Mosley, Garrett L; Nguyen, Phuong; Wu, Benjamin M; Kamei, Daniel T

2016-08-07

The lateral-flow immunoassay (LFA) is a well-established diagnostic technology that has recently seen significant advancements due in part to the rapidly expanding fields of paper diagnostics and paper-fluidics. As LFA-based diagnostics become more complex, it becomes increasingly important to quantitatively determine important parameters during the design and evaluation process. However, current experimental methods for determining these parameters have certain limitations when applied to LFA systems. In this work, we describe our novel methods of combining paper and radioactive measurements to determine nanoprobe molarity, the number of antibodies per nanoprobe, and the forward and reverse rate constants for nanoprobe binding to immobilized target on the LFA test line. Using a model LFA system that detects for the presence of the protein transferrin (Tf), we demonstrate the application of our methods, which involve quantitative experimentation and mathematical modeling. We also compare the results of our rate constant experiments with traditional experiments to demonstrate how our methods more appropriately capture the influence of the LFA environment on the binding interaction. Our novel experimental approaches can therefore more efficiently guide the research process for LFA design, leading to more rapid advancement of the field of paper-based diagnostics.

Loop-Mediated Isothermal Amplification-Lateral-Flow Dipstick (LAMP-LFD) to detect Toxoplasma gondii oocyst in ready-to-eat salad.

PubMed

Lalle, Marco; Possenti, Alessia; Dubey, Jitender P; Pozio, Edoardo

2018-04-01

The apicomplexan parasite Toxoplasma gondii is the causative agent of toxoplasmosis, a foodborne zoonosis with a global distribution and estimated to cause up to 20% of the total foodborne disease burden in Europe. Association between T. gondii infection and the consumption of unwashed raw fruits and vegetables contaminated with oocysts has been reported and the increasing habit to eat pre-washed ready-to-eat salads poses a new potential risk for consumers. It is therefore important to trace the occurrence of potential contamination with this parasite to guarantee the safety of ready-to-eat vegetables. Detection of T. gondii in vegetables by molecular techniques has been achieved but low sensitivity (PCR) or expensive equipments (qPCR) limit routine applicability. Here, we describe the development and validation of a sensitive and robust method relying on a LAMP assay, targeting the 529 bp locus, to detect T. gondii oocysts down to 25 oocysts/50 g in ready-to-eat baby lettuce. The LAMP has been also adapted for a faster visualization of the result by a lateral flow dipstick chromatographic detection method. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simple System for Isothermal DNA Amplification Coupled to Lateral Flow Detection

PubMed Central

Roskos, Kristina; Hickerson, Anna I.; Lu, Hsiang-Wei; Ferguson, Tanya M.; Shinde, Deepali N.; Klaue, Yvonne; Niemz, Angelika

2013-01-01

Infectious disease diagnosis in point-of-care settings can be greatly improved through integrated, automated nucleic acid testing devices. We have developed an early prototype for a low-cost system which executes isothermal DNA amplification coupled to nucleic acid lateral flow (NALF) detection in a mesofluidic cartridge attached to a portable instrument. Fluid handling inside the cartridge is facilitated through one-way passive valves, flexible pouches, and electrolysis-driven pumps, which promotes a compact and inexpensive instrument design. The closed-system disposable prevents workspace amplicon contamination. The cartridge design is based on standard scalable manufacturing techniques such as injection molding. Nucleic acid amplification occurs in a two-layer pouch that enables efficient heat transfer. We have demonstrated as proof of principle the amplification and detection of Mycobacterium tuberculosis (M.tb) genomic DNA in the cartridge, using either Loop Mediated Amplification (LAMP) or the Exponential Amplification Reaction (EXPAR), both coupled to NALF detection. We envision that a refined version of this cartridge, including upstream sample preparation coupled to amplification and detection, will enable fully-automated sample-in to answer-out infectious disease diagnosis in primary care settings of low-resource countries with high disease burden. PMID:23922706

Lateral Flow Rapid Test for Accurate and Early Diagnosis of Scrub Typhus: A Febrile Illness of Historically Military Importance in the Pacific Rim.

PubMed

Chao, Chien-Chung; Zhangm, Zhiwen; Weissenberger, Giulia; Chen, Hua-Wei; Ching, Wei-Mei

2017-03-01

Scrub typhus (ST) is an infection caused by Orientia tsutsugamushi. Historically, ST was ranked as the second most important arthropod-borne medical problem only behind malaria during World War II and the Vietnam War. The disease occurs mainly in Southeast Asia and has been shown to emerge and reemerge in new areas, implying the increased risk for U.S. military and civilian personnel deployed to these regions. ST can effectively be treated by doxycycline provided the diagnosis is made early, before the development of severe complications. Scrub Typhus Detect is a lateral flow rapid test based on a mixture of recombinant 56-kDa antigens with broad reactivity. The performance of this prototype product was evaluated against indirect immunofluorescence assay, the serological gold standard. Using 249 prospectively collected samples from Thailand, the sensitivity and specificity for IgM was found to be 100% and 92%, respectively, suggesting a high potential of this product for clinical use. This product will provide a user friendly, rapid, and accurate diagnosis of ST for clinicians to provide timely and accurate treatments of deployed personnel. Reprint & Copyright © 2017 Association of Military Surgeons of the U.S.

Visualization and contractile activity of cochlear pericytes in the capillaries of the spiral ligament.

PubMed

Dai, Min; Nuttall, Alfred; Yang, Yue; Shi, Xiaorui

2009-08-01

Pericytes, mural cells located on microvessels, are considered to play an important role in the formation of the vasculature and the regulation of local blood flow in some organs. Little is known about the physiology of cochlear pericytes. In order to investigate the function of cochlear pericytes, we developed a method to visualize cochlear pericytes using diaminofluorescein-2 diacetate (DAF-2DA) and intravital fluorescence microscopy. This method can permit the study of the effect of vasoactive agents on pericytes under the in vivo and normal physiological condition. The specificity of the labeling method was verified by the immunofluorescence labeling of pericyte maker proteins such as desmin, neural proteoglycan (NG2), and thymocyte differentiation antigen 1 (Thy-1). Superfused K(+) and Ca(2+) to the cochlear lateral wall resulted in localized constriction of capillaries at pericyte locations both in vivo and in vitro, while there was no obvious change in cochlear capillary diameters with application of the adrenergic neurotransmitter noradrenaline. The method could be an effective way to visualize cochlear pericytes and microvessels and study lateral wall vascular physiology. Moreover, we demonstrate for the first time that cochlear pericytes have contractility, which may be important for regulation of cochlear blood flow.

Enhanced biodegradation by hydraulic heterogeneities in petroleum hydrocarbon plumes.

PubMed

Bauer, Robert D; Rolle, Massimo; Bauer, Sebastian; Eberhardt, Christina; Grathwohl, Peter; Kolditz, Olaf; Meckenstock, Rainer U; Griebler, Christian

2009-02-27

In case of dissolved electron donors and acceptors, natural attenuation of organic contaminant plumes in aquifers is governed by hydrodynamic mixing and microbial activity. Main objectives of this work were (i) to determine whether aerobic and anaerobic biodegradation in porous sediments is controlled by transverse dispersion, (ii) to elucidate the effect of sediment heterogeneity on mixing and biodegradation, and (iii) to search for degradation-limiting factors. Comparative experiments were conducted in two-dimensional sediment microcosms. Aerobic toluene and later ethylbenzene degradation by Pseudomonas putida strain F1 was initially followed in a plume developing from oxic to anoxic conditions and later under steady-state mixing-controlled conditions. Competitive anaerobic degradation was then initiated by introduction of the denitrifying strain Aromatoleum aromaticum EbN1. In homogeneous sand, aerobic toluene degradation was clearly controlled by dispersive mixing. Similarly, under denitrifying conditions, microbial activity was located at the plume's fringes. Sediment heterogeneity caused flow focusing and improved the mixing of reactants. Independent from the electron accepting process, net biodegradation was always higher in the heterogeneous setting with a calculated efficiency plus of 23-100% as compared to the homogeneous setup. Flow and reactive transport model simulations were performed in order to interpret and evaluate the experimental results.

A Paper and Plastic Device for Performing Recombinase Polymerase Amplification of HIV DNA

PubMed Central

Rohrman, Brittany A.; Richards-Kortum, Rebecca R.

2013-01-01

Despite the importance of early diagnosis and treatment of HIV, only a small fraction of HIV-exposed infants in low- and middle-income countries are tested for the disease. The gold standard for early infant diagnosis, DNA PCR, requires resources that are unavailable in poor settings, and no point-of-care HIV DNA test is currently available. We have developed a device constructed of layers of paper, glass fiber, and plastic that is capable of performing isothermal, enzymatic amplification of HIV DNA. The device is inexpensive, small, light-weight, and easy to assemble. The device stores lyophilized enzymes, facilitates mixing of reaction components, and supports recombinase polymerase amplification in five steps of operation. Using commercially available lateral flow strips as a detection method, we demonstrate the ability of our device to amplify 10 copies of HIV DNA to detectable levels in 15 minutes. Our results suggest that our device, which is designed to be used after DNA extraction from dried-blood spots, may serve in conjunction with lateral flow strips as part of a point-of-care HIV DNA test to be used in low resource settings. PMID:22733333

A paper and plastic device for performing recombinase polymerase amplification of HIV DNA.

PubMed

Rohrman, Brittany A; Richards-Kortum, Rebecca R

2012-09-07

Despite the importance of early diagnosis and treatment of HIV, only a small fraction of HIV-exposed infants in low- and middle-income countries are tested for the disease. The gold standard for early infant diagnosis, DNA PCR, requires resources that are unavailable in poor settings, and no point-of-care HIV DNA test is currently available. We have developed a device constructed of layers of paper, glass fiber, and plastic that is capable of performing isothermal, enzymatic amplification of HIV DNA. The device is inexpensive, small, light-weight, and easy to assemble. The device stores lyophilized enzymes, facilitates mixing of reaction components, and supports recombinase polymerase amplification in five steps of operation. Using commercially available lateral flow strips as a detection method, we demonstrate the ability of our device to amplify 10 copies of HIV DNA to detectable levels in 15 min. Our results suggest that our device, which is designed to be used after DNA extraction from dried-blood spots, may serve in conjunction with lateral flow strips as part of a point-of-care HIV DNA test to be used in low resource settings.

Rapid Identification of OXA-48 and OXA-163 Subfamilies in Carbapenem-Resistant Gram-Negative Bacilli with a Novel Immunochromatographic Lateral Flow Assay.

PubMed

Pasteran, Fernando; Denorme, Laurence; Ote, Isabelle; Gomez, Sonia; De Belder, Denise; Glupczynski, Youri; Bogaerts, Pierre; Ghiglione, Barbara; Power, Pablo; Mertens, Pascal; Corso, Alejandra

2016-11-01

We assessed a novel immunochromatographic lateral flow assay for direct identification of OXA-48-like carbapenemases and accurate differentiation of allele variants with distinct substrate profiles (OXA-48 or OXA-163 subfamilies). The assay allowed rapid (less than 4 min) and reliable direct confirmation of OXA-163- and/or OXA-48-like enzymes (with 100% sensitivity and 100% specificity) from cultured colonies that were recovered from both solid medium and spiked blood culture bottles. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Development and Demonstration of Material Properties Database and Software for the Simulation of Flow Properties in Cementitious Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, F.; Flach, G.

This report describes work performed by the Savannah River National Laboratory (SRNL) in fiscal year 2014 to develop a new Cementitious Barriers Project (CBP) software module designated as FLOExcel. FLOExcel incorporates a uniform database to capture material characterization data and a GoldSim model to define flow properties for both intact and fractured cementitious materials and estimate Darcy velocity based on specified hydraulic head gradient and matric tension. The software module includes hydraulic parameters for intact cementitious and granular materials in the database and a standalone GoldSim framework to manipulate the data. The database will be updated with new data asmore » it comes available. The software module will later be integrated into the next release of the CBP Toolbox, Version 3.0. This report documents the development efforts for this software module. The FY14 activities described in this report focused on the following two items that form the FLOExcel package; 1) Development of a uniform database to capture CBP data for cementitious materials. In particular, the inclusion and use of hydraulic properties of the materials are emphasized; and 2) Development of algorithms and a GoldSim User Interface to calculate hydraulic flow properties of degraded and fractured cementitious materials. Hydraulic properties are required in a simulation of flow through cementitious materials such as Saltstone, waste tank fill grout, and concrete barriers. At SRNL these simulations have been performed using the PORFLOW code as part of Performance Assessments for salt waste disposal and waste tank closure.« less

Longitudinal variation in lateral trapping of fine sediment in tidal estuaries: observations and a 3D exploratory model

NASA Astrophysics Data System (ADS)

Chen, Wei; de Swart, Huib E.

2018-03-01

This study investigates the longitudinal variation of lateral entrapment of suspended sediment, as is observed in some tidal estuaries. In particular, field data from the Yangtze Estuary are analysed, which reveal that in one cross-section, two maxima of suspended sediment concentration (SSC) occur close to the south and north sides, while in a cross-section 2 km down-estuary, only one SSC maximum on the south side is present. This pattern is found during both spring tide and neap tide, which are characterised by different intensities of turbulence. To understand longitudinal variation in lateral trapping of sediment, results of a new three-dimensional exploratory model are analysed. The hydrodynamic part contains residual flow due to fresh water input, density gradients and Coriolis force and due to channel curvature-induced leakage. Moreover, the model includes a spatially varying eddy viscosity that accounts for variation of intensity of turbulence over the spring-neap cycle. By imposing morphodynamic equilibrium, the two-dimensional distribution of sediment in the domain is obtained analytically by a novel procedure. Results reveal that the occurrence of the SSC maxima near the south side of both cross-sections is due to sediment entrapment by lateral density gradients, while the second SSC maximum near the north side of the first cross-section is by sediment transport due to curvature-induced leakage. Coriolis deflection of longitudinal flow also contributes the trapping of sediment near the north side. This mechanism is important in the upper estuary, where the flow due to lateral density gradients is weak.

Giant oscillations of the current in a dirty 2D electron system flowing perpendicular to a lateral barrier under magnetic field

NASA Astrophysics Data System (ADS)

Kadigrobov, A. M.

2017-08-01

The charge transport in a dirty 2-dimensional electron system biased in the presence of a lateral potential barrier under magnetic field is theoretically studied. The quantum tunnelling across the barrier provides the quantum interference of the edge states localized on its both sides that results in giant oscillations of the charge current flowing perpendicular to the lateral junction. Our theoretical analysis is in a good agreement with the experimental observations presented in Kang et al. [Lett. Nat. 403, 59 (2000)]. In particular, positions of the conductance maxima coincide with the Landau levels while the conductance itself is essentially suppressed even at the energies at which the resonant tunnelling occurs and hence these puzzling observations can be resolved without taking into account the electron-electron interaction.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loisel, V.; Abbas, M., E-mail: micheline.abbas@ensiacet.fr; Masbernat, O.

Laminar pressure-driven suspension flows are studied in the situation of neutrally buoyant particles at finite Reynolds number. The numerical method is validated for homogeneous particle distribution (no lateral migration across the channel): the increase of particle slip velocities and particle stress with inertia and concentration is in agreement with former works in the literature. In the case of a two-phase channel flow with freely moving particles, migration towards the channel walls due to the Segré-Silberberg effect is observed, leading to the development of a non-uniform concentration profile in the wall-normal direction (the concentration peaks in the wall region and tendsmore » towards zero in the channel core). The particle accumulation in the region of highest shear favors the shear-induced particle interactions and agitation, the profile of which appears to be correlated to the concentration profile. A 1D model predicting particle agitation, based on the kinetic theory of granular flows in the quenched state regime when Stokes number St = O(1) and from numerical simulations when St < 1, fails to reproduce the agitation profile in the wall normal direction. Instead, the existence of secondary flows is clearly evidenced by long time simulations. These are composed of a succession of contra-rotating structures, correlated with the development of concentration waves in the transverse direction. The mechanism proposed to explain the onset of this transverse instability is based on the development of a lift force induced by spanwise gradient of the axial velocity fluctuations. The establishment of the concentration profile in the wall-normal direction therefore results from the combination of the mean flow Segré-Silberberg induced migration, which tends to stratify the suspension and secondary flows which tend to mix the particles over the channel cross section.« less

Measuring hemodynamics in the developing heart tube with four-dimensional gated Doppler optical coherence tomography

NASA Astrophysics Data System (ADS)

Jenkins, Michael W.; Peterson, Lindsy; Gu, Shi; Gargesha, Madhusudhana; Wilson, David L.; Watanabe, Michiko; Rollins, Andrew M.

2010-11-01

Hemodynamics is thought to play a major role in heart development, yet tools to quantitatively assess hemodynamics in the embryo are sorely lacking. The especially challenging analysis of hemodynamics in the early embryo requires new technology. Small changes in blood flow could indicate when anomalies are initiated even before structural changes can be detected. Furthermore, small changes in the early embryo that affect blood flow could lead to profound abnormalities at later stages. We present a demonstration of 4-D Doppler optical coherence tomography (OCT) imaging of structure and flow, and present several new hemodynamic measurements on embryonic avian hearts at early stages prior to the formation of the four chambers. Using 4-D data, pulsed Doppler measurements could accurately be attained in the inflow and outflow of the heart tube. Also, by employing an en-face slice from the 4-D Doppler image set, measurements of stroke volume and cardiac output are obtained without the need to determine absolute velocity. Finally, an image plane orthogonal to the blood flow is used to determine shear stress by calculating the velocity gradient normal to the endocardium. Hemodynamic measurements will be crucial to identifying genetic and environmental factors that lead to congenital heart defects.

Following a river wherever it goes: beneath the surface of mountain streams.

Treesearch

Jonathan Thompson; Sally Duncan

2004-01-01

The flow of a mountain stream is difficult to follow, especially when it weaves in and out of the channel, flowing through streambanks and seeping through the streambed. Flowing belowground, the stream water mixes with ground water in the riparian aquifer before reemerging in the channel, sometime later and somewhere further downstream. Underground, the water undergoes...

Erosional furrows formed during the lateral blast at Mount St. Helens, May 18, 1980

USGS Publications Warehouse

Kieffer, S.W.; Sturtevant, B.

1988-01-01

Nearly horizontal, quasi-periodic erosional features of 7-m average transverse wavelength and of order 100-m length occur in scattered locations from 3.5 to 9 km from the crater at Mount St. Helens under deposits of the lateral blast of May 18, 1980. We attribute the erosional features to scouring by longitudinal vortices resulting from flow instabilities induced by complex topography, namely, by streamline curvature in regions of reattachment downstream of sheltered regions, and by the cross-flow component of flow subparallel to ridge crests. The diameter of the vortices and their transverse spacing, inferred from the distance between furrows, are taken to be of the order of the boundary layer thickness. The inferred boundary layer thickness (???14 m at 9 km from the source of the blast) is consistent with the running length from the mountain to the furrow locations. The orientation of furrows induced by the cross-flow instability can be used to measure the upwash angle and estimate the flow Mach number: at the central ridge of Spirit Lake the Mach number is inferred to have been about 2.5, and the flow velocity approximately 235 m/s. -from Authors

Turbulent Friction in the Boundary Layer of a Flat Plate in a Two-Dimensional Compressible Flow at High Speeds

NASA Technical Reports Server (NTRS)

Frankl, F.; Voishel, V.

1943-01-01

In the present report an investigation is made on a flat plate in a two-dimensional compressible flow of the effect of compressibility and heating on the turbulent frictional drag coefficient in the boundary layer of an airfoil or wing radiator. The analysis is based on the Prandtl-Karman theory of the turbulent boundary later and the Stodola-Crocco, theorem on the linear relation between the total energy of the flow and its velocity. Formulas are obtained for the velocity distribution and the frictional drag law in a turbulent boundary later with the compressibility effect and heat transfer taken into account. It is found that with increase of compressibility and temperature at full retardation of the flow (the temperature when the velocity of the flow at a given point is reduced to zero in case of an adiabatic process in the gas) at a constant R (sub x), the frictional drag coefficient C (sub f) decreased, both of these factors acting in the same sense.

Genome biogeography reveals the intraspecific spread of adaptive mutations for a complex trait.

PubMed

Olofsson, Jill K; Bianconi, Matheus; Besnard, Guillaume; Dunning, Luke T; Lundgren, Marjorie R; Holota, Helene; Vorontsova, Maria S; Hidalgo, Oriane; Leitch, Ilia J; Nosil, Patrik; Osborne, Colin P; Christin, Pascal-Antoine

2016-12-01

Physiological novelties are often studied at macro-evolutionary scales such that their micro-evolutionary origins remain poorly understood. Here, we test the hypothesis that key components of a complex trait can evolve in isolation and later be combined by gene flow. We use C 4 photosynthesis as a study system, a derived physiology that increases plant productivity in warm, dry conditions. The grass Alloteropsis semialata includes C 4 and non-C 4 genotypes, with some populations using laterally acquired C 4 -adaptive loci, providing an outstanding system to track the spread of novel adaptive mutations. Using genome data from C 4 and non-C 4 A. semialata individuals spanning the species' range, we infer and date past migrations of different parts of the genome. Our results show that photosynthetic types initially diverged in isolated populations, where key C 4 components were acquired. However, rare but recurrent subsequent gene flow allowed the spread of adaptive loci across genetic pools. Indeed, laterally acquired genes for key C 4 functions were rapidly passed between populations with otherwise distinct genomic backgrounds. Thus, our intraspecific study of C 4 -related genomic variation indicates that components of adaptive traits can evolve separately and later be combined through secondary gene flow, leading to the assembly and optimization of evolutionary innovations. © 2016 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

Assembling an ignimbrite: Compositionally defined eruptive packages in the 1912 Valley of Ten Thousand Smokes ignimbrite, Alaska

USGS Publications Warehouse

Fierstein, J.; Wilson, C.J.N.

2005-01-01

The 1912 Valley of Ten Thousand Smokes (VTTS) ignimbrite was constructed from 9 compositionally distinct, sequentially emplaced packages, each with distinct proportions of rhyolite (R), dacite (D), and andesite (A) pumices that permit us to map package boundaries and flow paths from vent to distal extents. Changing pumice proportions and interbedding relationships link ignimbrite formation to coeval fall deposition during the first ???16 h (Episode I) of the eruption. Pumice compositional proportions in the ignimbrite were estimated by counts on ???100 lapilli at multiple levels in vertical sections wherever accessible and more widely over most of the ignimbrite surface in the VTTS. The initial, 100% rhyolite ignimbrite package (equivalent to regional fall Layer A and occupying ???3.5 h) was followed by packages with increasing proportions of andesite, then dacite, emplaced over ???12.5 h and equivalent to regional fall Layers B1-B3. Coeval fall deposits are locally intercalated with the ignimbrite and show parallel changes in R:D (rhyolite:dacite) proportions, but lack significant amounts of andesite. Andesite was thus dominantly a low-fountaining component in the eruption column and is preferentially represented in packages filling the VTTS north of the vent. The most extensive packages (3 and 4) occur in B1 and early B2 times where flow mobility and volume were optimized; earlier all-rhyolite flows (Package 1) were highly energetic but less voluminous, while later packages (5-9) were both less voluminous and emplaced at lower velocities. Package boundaries are expressed as one or more of the following: sharp color changes corresponding to compositional variations; persistent finer-grained basal parts of flow units; compaction swales filled by later packages; erosional channels cut by the flows that fill them; lobate accumulations of one package; and (mostly south of the vent) intercalated fall deposit layers. Clear flow-unit boundaries are best developed between ignimbrite of non-successive packages, indicating time breaks of tens of minutes to hours. Less well-defined stratification may represent rapidly emplaced successive flow units but often changes over short distances and indicates variations in localized depositional conditions. ?? 2005 Geological Society of America.

Computational Fluid Dynamics of Developing Avian Outflow Tract Heart Valves

PubMed Central

Bharadwaj, Koonal N.; Spitz, Cassie; Shekhar, Akshay; Yalcin, Huseyin C.; Butcher, Jonathan T.

2012-01-01

Hemodynamic forces play an important role in sculpting the embryonic heart and its valves. Alteration of blood flow patterns through the hearts of embryonic animal models lead to malformations that resemble some clinical congenital heart defects, but the precise mechanisms are poorly understood. Quantitative understanding of the local fluid forces acting in the heart has been elusive because of the extremely small and rapidly changing anatomy. In this study, we combine multiple imaging modalities with computational simulation to rigorously quantify the hemodynamic environment within the developing outflow tract (OFT) and its eventual aortic and pulmonary valves. In vivo Doppler ultrasound generated velocity profiles were applied to Micro-Computed Tomography generated 3D OFT lumen geometries from Hamburger-Hamilton (HH) stage 16 to 30 chick embryos. Computational fluid dynamics simulation initial conditions were iterated until local flow profiles converged with in vivo Doppler flow measurements. Results suggested that flow in the early tubular OFT (HH16 and HH23) was best approximated by Poiseuille flow, while later embryonic OFT septation (HH27, HH30) was mimicked by plug flow conditions. Peak wall shear stress (WSS) values increased from 18.16 dynes/cm2 at HH16 to 671.24 dynes/cm2 at HH30. Spatiotemporally averaged WSS values also showed a monotonic increase from 3.03 dynes/cm2 at HH16 to 136.50 dynes/cm2 at HH30. Simulated velocity streamlines in the early heart suggest a lack of mixing, which differed from classical ink injections. Changes in local flow patterns preceded and correlated with key morphogenetic events such as OFT septation and valve formation. This novel method to quantify local dynamic hemodynamics parameters affords insight into sculpting role of blood flow in the embryonic heart and provides a quantitative baseline dataset for future research. PMID:22535311

Magmatic structures in the Krkonoše Jizera Plutonic Complex, Bohemian Massif: evidence for localized multiphase flow and small-scale thermal mechanical instabilities in a granitic magma chamber

NASA Astrophysics Data System (ADS)

Žák, Jiří; Klomínský, Josef

2007-08-01

The present paper examines magmatic structures in the Jizera and Liberec granites of the Krkonoše-Jizera Plutonic Complex, Bohemian Massif. The magmatic structures are here interpreted to preserve direct field evidence for highly localized magma flow and other processes in crystal-rich mushes, and to capture the evolution of physical processes in an ancient granitic magma chamber. We propose that after chamber-wide mixing and hybridization, as suggested by recent petrological studies, laminar magma flow became highly localized to weaker channel-like domains within the higher-strength crystal framework. Mafic schlieren formed at flow rims, and their formation presumably involved gravitational settling and velocity gradient flow sorting coupled with interstitial melt escape. Local thermal or compositional convection may have resulted in the formation of vertical schlieren tubes and ladder dikes whereas subhorizontal tubes or channels formed during flow driven by lateral gradients in magma pressure. After the cessation or deceleration of channel flow, gravity-driven processes (settling of crystals and enclaves, gravitational differentiation, development of downward dripping instabilities), accompanied by compaction, filter pressing and melt segregation, dominated in the crystal mush within the flow channels. Subsequently, magmatic folds developed in schlieren layers and the magma chamber recorded complex, late magmatic strains at high magma crystallinities. Late-stage magma pulsing into localized submagmatic cracks represents the latest events of magmatic history of the chamber prior to its final crystallization. We emphasize that the most favorable environments for the formation and preservation of magmatic structures, such as those hosted in the Jizera and Liberec granites, are slowly cooling crystal-rich mushes. Therefore, where preserved in plutons, these structures may lend strong support for a "mush model" of magmatic systems.

High-resolution characterization of chemical heterogeneity in an alluvial aquifer

USGS Publications Warehouse

Schulmeister, M.K.; Healey, J.M.; Butler, J.J.; McCall, G.W.; Birk, S.

2002-01-01

The high-resolution capabilities of direct push technology were exploited to develop new insights into the hydrochemistry at the margin of an alluvial aquifer. Hydrostratigraphic controls on groundwater flow and contaminant loading were revealed through the combined use of direct push electrical conductivity (EC) logging and geochemical profiling. Vertical and lateral variations in groundwater chemistry were consistent with sedimentary features indicated by EC logs, and were supported by a conceptual model of recharge along the flood plain margin.

Comparing internal migration across the countries of Latin America: A multidimensional approach

PubMed Central

Bernard, Aude; Rowe, Francisco; Bell, Martin; Ueffing, Philipp; Charles-Edwards, Elin

2017-01-01

While considerable progress has been made in understanding the way particular aspects of internal migration, such as its intensity, age profile and spatial impact, vary between countries around the world, little attention to date has been given to establishing how these dimensions of migration interact in different national settings. We use recently developed measures of internal migration that are scale-independent to compare the overall intensity, age composition, spatial impact, and distance profile of internal migration in 19 Latin American countries. Comparisons reveal substantial cross-national variation but cluster analysis suggests the different dimensions of migration evolve systematically to form a broad sequence characterised by low intensities, young ages at migration, unbalanced flows and high friction of distance at lower levels of development, trending to high intensities, an older age profile of migration, more closely balanced flows and lower friction of distance at later stages of development. However, the transition is not linear and local contingencies, such as international migration and political control, often distort the migration-development nexus, leading to unique migration patterns in individual national contexts. PMID:28328932

Migrating Toward Fully 4-D Geodynamical Models of Asthenospheric Circulation and Melt Production at Mid-Ocean Ridges

NASA Astrophysics Data System (ADS)

van Dam, L.; Kincaid, C. R.; Pockalny, R. A.; Sylvia, R. T.; Hall, P. S.

2017-12-01

Lateral migration of mid-ocean ridge spreading centers is a well-documented phenomenon leading to asymmetric melt production and the surficial expressions thereof. This form of plate motion has been difficult to incorporate into both numerical and analogue geodynamical models, and consequently, current estimates of time-dependent flow, material transport, and melting in the mantle beneath ridges are lacking. To address this, we have designed and built an innovative research apparatus that allows for precise and repeatable simulations of mid-ocean ridge spreading and migration. Three pairs of counter-rotating belts with adjustable lateral orientations are scaled to simulate spreading at, and flow beneath, three 600km wide ridge segments with up to 300km transform offsets. This apparatus is attached to a drive system that allows us to test a full range of axis-parallel to axis-normal migration directions, and is suspended above a reservoir of viscous glucose syrup, a scaled analogue for the upper mantle, and neutrally buoyant tracers. We image plate-driven flow in the syrup with high-resolution digital cameras and use particle image velocimetry methods to obtain information about transport pathlines and flow-induced anisotropy. Suites of experiments are run with and without ridge migration to determine the overall significance of migration on spatial and temporal characteristics of shallow mantle flow. Our experiments cover an expansive parameter space by including various spreading rates, migration speeds and directions, degrees of spreading asymmetry, transform-offset lengths, and upper mantle viscosity conditions. Preliminary results highlight the importance of modeling migratory plate forces. Mantle material exhibits a significant degree of lateral transport, particularly between ridge segments and towards the melt triangle. Magma supply to the melting region is highly complex; parcels of material do not necessarily move along fixed streamlines, rather, they can be perturbed upwards and left behind as spreading centers continue to move laterally. These results emphasize that observations of seismic anisotropy should be interpreted in light of intricate flow pathlines, and that melt transport models should consider different paths for melt relative to the solid matrix.

A comprehensive review of the foramina of Luschka: history, anatomy, embryology, and surgery.

PubMed

Johal, Jaspreet; Paulk, Phillip Barrett; Oakes, Peter C; Oskouian, Rod J; Loukas, Marios; Tubbs, R Shane

2017-09-01

The purpose of this review is to comprehensively review the foramina of Luschka in regard to their discovery, embryology, anatomy, and surgical relevance. This subject review of the foramina of Luschka was composed after conducting a thorough review of the available literature on this topic using PubMed and other primary sources. The foramina of Luschka are paired apertures located in the lateral recesses of the fourth ventricle, within the posterior cranial fossa. The foramina of Luschka are of importance clinically as their blockage can disrupt the flow of cerebrospinal fluid leading to the development of hydrocephalus. These apertures were first described by the German anatomist Hubert von Luschka in the nineteenth century. These foramina are thought to emerge at around the 26th week of development. The apertures project into the cerebellopontine angle at the lateral border of the pontomedullary sulcus. The foramina of Luschka may be surgically manipulated for the excision of tumors involving the fourth ventricle and surrounding structures and accessed for cochlear nucleus stimulation.

Earthflow yield strength constrained by lateral levee morphology

NASA Astrophysics Data System (ADS)

Nereson, A. L.; Finnegan, N. J.

2015-12-01

Slow-moving landslides, or earthflows, are characterized by persistent, flow-like motion that is commonly modeled using various viscous and viscoplastic rheologies. One of the manifestations of viscoplastic flow down a slope is the emergence of stationary bodies of fluid at the margins of the flow (i.e. lateral levees). These levees are common signatures of earthflow morphology and, while they are frequently used to outline boundaries for mapping purposes, they have received little attention for what they may indicate about the history and properties of the flow itself. In contrast, lateral levees along lava flows have long been used by physical volcanologists as tools to learn about their non-Newtonian rheologies and chemical compositions. Hulme (1974) was the first to note that, for a given slope, levee width may be characteristic of a fluids's yield strength and his methodology has been subsequently used to infer properties of lavas on the Earth, the Moon, and Mars. Using these lavas as analogies, we apply Hulme's approach to earthflows in a variety of settings globally. We find that calculated yield strengths for individual earthflows fall within a relatively narrow range between 101-102 kPa. In addition, individual earthflow complexes often preserve multiple generations of levees, which in some cases may record apparent reductions in yield strength over time for a given flow, possibly from weakening of previously failed material. Knowledge of earthflow yield strength permits the calculation of a critical earthflow thickness below which there will be no downslope motion for a given slope angle. Thicknesses calculated in this manner could thus be used to estimate the flux of landslide material for earthflows without direct depth constraints, provided that surface velocity measurements are obtained by other methods (e.g. InSAR, GPS, manual feature tracking).

Flow of variably fluidized granular masses across three-dimensional terrain 2. Numerical predictions and experimental tests

USGS Publications Warehouse

Denlinger, R.P.; Iverson, R.M.

2001-01-01

Numerical solutions of the equations describing flow of variably fluidized Coulomb mixtures predict key features of dry granular avalanches and water-saturated debris flows measured in physical experiments. These features include time-dependent speeds, depths, and widths of flows as well as the geometry of resulting deposits. Threedimensional (3-D) boundary surfaces strongly influence flow dynamics because transverse shearing and cross-stream momentum transport occur where topography obstructs or redirects motion. Consequent energy dissipation can cause local deceleration and deposition, even on steep slopes. Velocities of surge fronts and other discontinuities that develop as flows cross 3-D terrain are predicted accurately by using a Riemann solution algorithm. The algorithm employs a gravity wave speed that accounts for different intensities of lateral stress transfer in regions of extending and compressing flow and in regions with different degrees of fluidization. Field observations and experiments indicate that flows in which fluid plays a significant role typically have high-friction margins with weaker interiors partly fluidized by pore pressure. Interaction of the strong perimeter and weak interior produces relatively steep-sided, flat-topped deposits. To simulate these effects, we compute pore pressure distributions using an advection-diffusion model with enhanced diffusivity near flow margins. Although challenges remain in evaluating pore pressure distributions in diverse geophysical flows, Riemann solutions of the depthaveraged 3-D Coulomb mixture equations provide a powerful tool for interpreting and predicting flow behavior. They provide a means of modeling debris flows, rock avalanches, pyroclastic flows, and related phenomena without invoking and calibrating Theological parameters that have questionable physical significance.

A refined and dynamic cellular automaton model for pedestrian-vehicle mixed traffic flow

NASA Astrophysics Data System (ADS)

Liu, Mianfang; Xiong, Shengwu

2016-12-01

Mixed traffic flow sharing the “same lane” and having no discipline on road is a common phenomenon in the developing countries. For example, motorized vehicles (m-vehicles) and nonmotorized vehicles (nm-vehicles) may share the m-vehicle lane or nm-vehicle lane and pedestrians may share the nm-vehicle lane. Simulating pedestrian-vehicle mixed traffic flow consisting of three kinds of traffic objects: m-vehicles, nm-vehicles and pedestrians, can be a challenge because there are some erratic drivers or pedestrians who fail to follow the lane disciplines. In the paper, we investigate various moving and interactive behavior associated with mixed traffic flow, such as lateral drift including illegal lane-changing and transverse crossing different lanes, overtaking and forward movement, and propose some new moving and interactive rules for pedestrian-vehicle mixed traffic flow based on a refined and dynamic cellular automaton (CA) model. Simulation results indicate that the proposed model can be used to investigate the traffic flow characteristic in a mixed traffic flow system and corresponding complicated traffic problems, such as, the moving characteristics of different traffic objects, interaction phenomenon between different traffic objects, traffic jam, traffic conflict, etc., which are consistent with the actual mixed traffic system. Therefore, the proposed model provides a solid foundation for the management, planning and evacuation of the mixed traffic flow.

Evolution of the conceptual model of unsaturated zone hydrology at Yucca Mountain, Nevada

USGS Publications Warehouse

Flint, Alan L.; Flint, Lorraine E.; Bodvarsson, Gudmundur S.; Kwicklis, Edward M.; Fabryka-Martin, June

2001-01-01

Yucca Mountain is an arid site proposed for consideration as the United States’ first underground high-level radioactive waste repository. Low rainfall (approximately 170 mm/yr) and a thick unsaturated zone (500–1000 m) are important physical attributes of the site because the quantity of water likely to reach the waste and the paths and rates of movement of the water to the saturated zone under future climates would be major factors in controlling the concentrations and times of arrival of radionuclides at the surrounding accessible environment. The framework for understanding the hydrologic processes that occur at this site and that control how quickly water will penetrate through the unsaturated zone to the water table has evolved during the past 15 yr. Early conceptual models assumed that very small volumes of water infiltrated into the bedrock (0.5–4.5 mm/yr, or 2–3 percent of rainfall), that much of the infiltrated water flowed laterally within the upper nonwelded units because of capillary barrier effects, and that the remaining water flowed down faults with a small amount flowing through the matrix of the lower welded, fractured rocks. It was believed that the matrix had to be saturated for fractures to flow. However, accumulating evidence indicated that infiltration rates were higher than initially estimated, such as infiltration modeling based on neutron borehole data, bomb-pulse isotopes deep in the mountain, perched water analyses and thermal analyses. Mechanisms supporting lateral diversion did not apply at these higher fluxes, and the flux calculated in the lower welded unit exceeded the conductivity of the matrix, implying vertical flow of water in the high permeability fractures of the potential repository host rock, and disequilibrium between matrix and fracture water potentials. The development of numerical modeling methods and parameter values evolved concurrently with the conceptual model in order to account for the observed field data, particularly fracture flow deep in the unsaturated zone. This paper presents the history of the evolution of conceptual models of hydrology and numerical models of unsaturated zone flow at Yucca Mountain, Nevada (Flint, A.L., Flint, L.E., Kwicklis, E.M., Bodvarsson, G.S., Fabryka-Martin, J.M., 2001. Hydrology of Yucca Mountain. Reviews of Geophysics in press). This retrospective is the basis for recommendations for optimizing the efficiency with which a viable and robust conceptual model can be developed for a complex site.

Lipopolysaccharide Specific Immunochromatography Based Lateral Flow Assay for Serogroup Specific Diagnosis of Leptospirosis in India

PubMed Central

Vanithamani, Shanmugam; Shanmughapriya, Santhanam; Narayanan, Ramasamy; Raja, Veerapandian; Kanagavel, Murugesan; Sivasankari, Karikalacholan; Natarajaseenivasan, Kalimuthusamy

2015-01-01

Background Leptospirosis is a re-emerging infectious disease that is under-recognized due to low-sensitivity and cumbersome serological tests. MAT is the gold standard test and it is the only serogroup specific test used till date. Rapid reliable alternative serogroup specific tests are needed for surveillance studies to identify locally circulating serogroups in the study area. Methods/Principal Findings In the present investigation the serological specificity of leptospiral lipopolysaccharides (LPS) was evaluated by enzyme linked immunosorbent assay (ELISA), dot blot assay and rapid immunochromatography based lateral flow assay (ICG-LFA). Sera samples from 120 MAT positive cases, 174 cases with febrile illness other than leptospirosis, and 121 seronegative healthy controls were evaluated for the diagnostic sensitivity and specificity of the developed assays. LPS was extracted from five locally predominant circulating serogroups including: Australis (27.5%), Autumnalis (11.7%), Ballum (25.8%), Grippotyphosa (12.5%), Pomona (10%) and were used as antigens in the diagnostics to detect IgM antibodies in patients’ sera. The sensitivity observed by IgM ELISA and dot blot assay using various leptospiral LPS was >90% for homologous sera. Except for Ballum LPS, no other LPS showed cross-reactivity to heterologous sera. An attempt was made to develop LPS based ICG-LFA for rapid and sensitive serogroup specific diagnostics of leptospirosis. The developed ICG-LFA showed sensitivity in the range between 93 and 100% for homologous sera. The Wilcoxon analysis showed LPS based ICG-LFA did not differ significantly from the gold standard MAT (P>0.05). Conclusion The application of single array of LPS for serogroup specific diagnosis is first of its kind. The developed assay could potentially be evaluated and employed for as MAT alternative. PMID:26340095

Subsurface lateral preferential flow network revealed by time-lapse ground-penetrating radar in a hillslope

NASA Astrophysics Data System (ADS)

Guo, Li; Chen, Jin; Lin, Henry

2014-12-01

Subsurface lateral preferential flow (LPF) has been observed to contribute substantially to hillslope and catchment runoff. However, the complex nature of LPF and the lack of an appropriate investigation method have hindered direct LPF observation in the field. Thus, the initiation, persistence, and dynamics of LPF networks remain poorly understood. This study explored the application of time-lapse ground-penetrating radar (GPR) together with an artificial infiltration to shed light on the nature of LPF and its dynamics in a hillslope. Based on our enhanced field experimental setup and carefully refined GPR data postprocessing algorithms, we developed a new protocol to reconstruct LPF networks with centimeter resolution. This is the first time that a detailed LPF network and its dynamics have been revealed noninvasively along a hillslope. Real-time soil water monitoring and field soil investigation confirmed the locations of LPF mapped by time-lapse GPR surveys. Our results indicated the following: (1) Increased spatial variations of radar signals after infiltration suggested heterogeneous soil water changes within the studied soil, which reflected the generation and dynamics of LPF; (2) Two types of LPF networks were identified, the network at the location of soil permeability contrasts and that formed via a series of connected preferential flow paths; and (3) The formation and distribution of LPF networks were influenced by antecedent soil water condition. Overall, this study demonstrates clearly that carefully designed time-lapse GPR surveys with enhanced data postprocessing offer a practical and nondestructive way of mapping LPF networks in the field, thereby providing a potentially significant enhancement in our ability to study complex subsurface flow processes across the landscape.

Alpha-defensin and the Synovasure lateral flow device for the diagnosis of prosthetic joint infection.

PubMed

Marson, B A; Deshmukh, S R; Grindlay, D J C; Scammell, B E

2018-06-01

Aims The aim of this review was to evaluate the available literature and to calculate the pooled sensitivity and specificity for the different alpha-defensin test systems that may be used to diagnose prosthetic joint infection (PJI). Materials and Methods Studies using alpha-defensin or Synovasure (Zimmer Biomet, Warsaw, Indiana) to diagnose PJI were identified from systematic searches of electronic databases. The quality of the studies was evaluated using the Quality Assessment of Studies of Diagnostic Accuracy (QUADAS) tool. Meta-analysis was completed using a bivariate model. Results A total of 11 eligible studies were included. The median QUADAS score was 13 (interquartile range 13 to 13) out of 14. Significant conflicts of interest were identified in five studies. The pooled sensitivity for the laboratory alpha-defensin test was 0.95 (95% confidence interval (CI) 0.91 to 0.98) and the pooled specificity was 0.97 (95% CI 0.95 to 0.98) for four studies with a threshold level of 5.2 mgl -1 The pooled sensitivity for the lateral flow cassette test was 0.85 (95% CI 0.74 to 0.92) and the pooled specificity was 0.90 (95% CI 0.91 to 0.98). There was a statistically significant difference in sensitivity (p = 0.019), but not specificity (p = 0.47). Conclusion Laboratory-based alpha-defensin testing remains a promising tool for diagnosing PJI. The lateral flow cassette has a significantly lower performance and pooled results are comparable to the leucocyte esterase test. Further studies are required before the widespread adoption of the lateral flow cassette alpha-defensin test. Cite this article: Bone Joint J 2018;100-B:703-11.

Influence of gas flow and applied voltage on interaction of jets in a cross-field helium plasma jet array

NASA Astrophysics Data System (ADS)

Wan, Meng; Liu, Feng; Fang, Zhi; Zhang, Bo; Wan, Hui

2017-09-01

Atmospheric Pressure Plasma Jet arrays can greatly enhance the treatment area to fulfill the need for large-scale surface processing, while the spatial uniformity of the plasma jet array is closely related to the interactions of the adjacent jets. In this paper, a three-tube one-dimensional (1D) He plasma jet array with a cross-field needle-ring electrode structure is used to investigate the influences of the gas flow rate and applied voltage on the interactions of the adjacent jets through electrical, optical, and fluid measurements. The repulsion of the adjacent plume channels is observed using an intensified charge-coupled device (ICCD) and the influence of the gas flow rate and applied voltage on the electrostatic repulsion force, Coulomb force, is discussed. It is found that electrical coupling, mainly electrostatic repulsion force, exists among the jets in the array, which causes both the divergence of the lateral plumes and the nonlinear changes of the discharge power and the transport charge. The deflection angle of the lateral plumes with respect to the central plume in the optical images increases with the increase of applied voltage and decreases with the increase of gas flow rate. The deflection angle of the lateral plumes in the optical images is obviously larger than that of the lateral gas streams in the Schlieren images under the same experimental conditions, and the unconformity of the deflection angles is mainly attributed to the electrostatic repulsion force in adjacent plasma plume channels. The experimental results can help understand the interaction mechanisms of jets in the array and design controllable and scalable plasma jet arrays.

Where and why hyporheic exchange is important: Inferences from a parsimonious, physically-based river network model

NASA Astrophysics Data System (ADS)

Gomez-Velez, J. D.; Harvey, J. W.

2014-12-01

Hyporheic exchange has been hypothesized to have basin-scale consequences; however, predictions throughout river networks are limited by available geomorphic and hydrogeologic data as well as models that can analyze and aggregate hyporheic exchange flows across large spatial scales. We developed a parsimonious but physically-based model of hyporheic flow for application in large river basins: Networks with EXchange and Subsurface Storage (NEXSS). At the core of NEXSS is a characterization of the channel geometry, geomorphic features, and related hydraulic drivers based on scaling equations from the literature and readily accessible information such as river discharge, bankfull width, median grain size, sinuosity, channel slope, and regional groundwater gradients. Multi-scale hyporheic flow is computed based on combining simple but powerful analytical and numerical expressions that have been previously published. We applied NEXSS across a broad range of geomorphic diversity in river reaches and synthetic river networks. NEXSS demonstrates that vertical exchange beneath submerged bedforms dominates hyporheic fluxes and turnover rates along the river corridor. Moreover, the hyporheic zone's potential for biogeochemical transformations is comparable across stream orders, but the abundance of lower-order channels results in a considerably higher cumulative effect for low-order streams. Thus, vertical exchange beneath submerged bedforms has more potential for biogeochemical transformations than lateral exchange beneath banks, although lateral exchange through meanders may be important in large rivers. These results have implications for predicting outcomes of river and basin management practices.

Simulation of freshwater-saltwater interfaces in the Brooklyn-Queens aquifer system, Long Island, New York

USGS Publications Warehouse

Kontis, Angelo L.

1999-01-01

The seaward limit of the fresh ground-water system underlying Kings and Queens Counties on Long Island, N.Y., is at the freshwater-saltwater transition zone. This zone has been conceptualized in transient-state, three-dimensional models of the aquifer system as a sharp interface between freshwater and saltwater, and represented as a stationary, zero lateral-flow boundary. In this study, a pair of two-dimensional, four-layer ground-water flow models representing a generalized vertical section in Kings County and one in adjacent Queens County were developed to evaluate the validity of the boundary condition used in three-dimensional models of the aquifer system. The two-dimensional simulations used a model code that can simulate the movement of a sharp interface in response to transient stress. Sensitivity of interface movement to four factors was analyzed; these were (1) the method of simulating vertical leakage between freshwater and saltwater; (2) recharge at the normal rate, at 50-percent of the normal rate, and at zero for a prolonged (3-year) period; (3) high, medium, and low pumping rates; and (4) pumping from a hypothetical cluster of wells at two locations. Results indicate that the response of the interfaces to the magnitude and duration of pumping and the location of the hypothetical wells is probably sufficiently slow that the interfaces in three-dimensional models can reasonably be approximated as stationary, zero-lateral- flow boundaries.

Modeling Streamflow and Water Temperature in the North Santiam and Santiam Rivers, Oregon, 2001-02

USGS Publications Warehouse

Sullivan, Annett B.; Roundsk, Stewart A.

2004-01-01

To support the development of a total maximum daily load (TMDL) for water temperature in the Willamette Basin, the laterally averaged, two-dimensional model CE-QUAL-W2 was used to construct a water temperature and streamflow model of the Santiam and North Santiam Rivers. The rivers were simulated from downstream of Detroit and Big Cliff dams to the confluence with the Willamette River. Inputs to the model included bathymetric data, flow and temperature from dam releases, tributary flow and temperature, and meteorologic data. The model was calibrated for the period July 1 through November 21, 2001, and confirmed with data from April 1 through October 31, 2002. Flow calibration made use of data from two streamflow gages and travel-time and river-width data. Temperature calibration used data from 16 temperature monitoring locations in 2001 and 5 locations in 2002. A sensitivity analysis was completed by independently varying input parameters, including point-source flow, air temperature, flow and water temperature from dam releases, and riparian shading. Scenario analyses considered hypothetical river conditions without anthropogenic heat inputs, with restored riparian vegetation, with minimum streamflow from the dams, and with a more-natural seasonal water temperature regime from dam releases.

Measurement of terms and parameters in turbulent models

NASA Technical Reports Server (NTRS)

Sandborn, Virgil A.

1989-01-01

Experimental measurements of the mean and turbulent velocity field in a water flow, turn-around-duct is documented. The small radius of curvature duct experiments were made over a range of Reynolds numbers (based on a duct height of 10 cm) from 70,000 to 500,000. For this particular channel, the flow is dominated by the inertia forces. Use of the local bulk velocity to non-dimensionalize the local velocity was found to limit Reynolds number effects to the regions very close to the wall. Only secondary effects on the flow field were observed when the inlet or exit boundary conditions were altered. The flow over the central two-thirds of the channel was two-dimensional. Mean tangetial and radial velocities, streamlines, pressure distributions, surface shear stress; tangential, radial and lateral turbulent velocities and the Reynolds turbulent shear values are tabulated in other reports. It is evident from the experimental study that a complex numerical modeling technique must be developed to predict the flow in the turn-around-duct. The model must be able to predict relaminarization along the inner-convex-wall. It must also allow for the major increase in turbulence produced by the outer-concave-wall.

Particle image velocimetry study of pulsatile flow in bi-leaflet mechanical heart valves with image compensation method.

PubMed

Shi, Yubing; Yeo, Tony Joon Hock; Zhao, Yong; Hwang, Ned H C

2006-12-01

Particle Image Velocimetry (PIV) is an important technique in studying blood flow in heart valves. Previous PIV studies of flow around prosthetic heart valves had different research concentrations, and thus never provided the physical flow field pictures in a complete heart cycle, which compromised their pertinence for a better understanding of the valvular mechanism. In this study, a digital PIV (DPIV) investigation was carried out with improved accuracy, to analyse the pulsatile flow field around the bi-leaflet mechanical heart valve (MHV) in a complete heart cycle. For this purpose a pulsatile flow test rig was constructed to provide the necessary in vitro test environment, and the flow field around a St. Jude size 29 bi-leaflet MHV and a similar MHV model were studied under a simulated physiological pressure waveform with flow rate of 5.2 l/min and pulse rate at 72 beats/min. A phase-locking method was applied to gate the dynamic process of valve leaflet motions. A special image-processing program was applied to eliminate optical distortion caused by the difference in refractive indexes between the blood analogue fluid and the test section. Results clearly showed that, due to the presence of the two leaflets, the valvular flow conduit was partitioned into three flow channels. In the opening process, flow in the two side channels was first to develop under the presence of the forward pressure gradient. The flow in the central channel was developed much later at about the mid-stage of the opening process. Forward flows in all three channels were observed at the late stage of the opening process. At the early closing process, a backward flow developed first in the central channel. Under the influence of the reverse pressure gradient, the flow in the central channel first appeared to be disturbed, which was then transformed into backward flow. The backward flow in the central channel was found to be the main driving factor for the leaflet rotation in the valve closing process. After the valve was fully closed, local flow activities in the proximity of the valve region persisted for a certain time before slowly dying out. In both the valve opening and closing processes, maximum velocity always appeared near the leaflet trailing edges. The flow field features revealed in the present paper improved our understanding of valve motion mechanism under physiological conditions, and this knowledge is very helpful in designing the new generation of MHVs.

Inferring common cognitive mechanisms from brain blood-flow lateralization data: a new methodology for fTCD analysis.

PubMed

Meyer, Georg F; Spray, Amy; Fairlie, Jo E; Uomini, Natalie T

2014-01-01

Current neuroimaging techniques with high spatial resolution constrain participant motion so that many natural tasks cannot be carried out. The aim of this paper is to show how a time-locked correlation-analysis of cerebral blood flow velocity (CBFV) lateralization data, obtained with functional TransCranial Doppler (fTCD) ultrasound, can be used to infer cerebral activation patterns across tasks. In a first experiment we demonstrate that the proposed analysis method results in data that are comparable with the standard Lateralization Index (LI) for within-task comparisons of CBFV patterns, recorded during cued word generation (CWG) at two difficulty levels. In the main experiment we demonstrate that the proposed analysis method shows correlated blood-flow patterns for two different cognitive tasks that are known to draw on common brain areas, CWG, and Music Synthesis. We show that CBFV patterns for Music and CWG are correlated only for participants with prior musical training. CBFV patterns for tasks that draw on distinct brain areas, the Tower of London and CWG, are not correlated. The proposed methodology extends conventional fTCD analysis by including temporal information in the analysis of cerebral blood-flow patterns to provide a robust, non-invasive method to infer whether common brain areas are used in different cognitive tasks. It complements conventional high resolution imaging techniques.

Overpressure, Flow Focusing, Compaction and Slope Stability on the continental slope: Insights from IODP Expedition 308

NASA Astrophysics Data System (ADS)

Flemings, P. B.

2010-12-01

Integrated Ocean Drilling Program Expepedition 308 used direct measurements of pore pressure, analysis of hydromechanical properties, and geological analysis to illuminate how sedimentation, flow focusing, overpressure, and slope stability couple beneath the seafloor on the deepwater continental slope in the Gulf of Mexico. We used pore pressure penetrometers to measure severe overpressures (60% of the difference between lithostatic stress and hydrostatic pressure) that extend from the seafloor for 100’s of meters. We ran uniaxial consolidation experiments on whole core and found that although permeability is relatively high near the seafloor, the sediments are highly compressible. As a result, the coefficient of consolidation (the hydraulic diffusivity) is remarkably constant over a large range of effective stresses. This behavior accounts for the high overpressure that begins near the seafloor and extends to depth. Forward modeling suggests that flow is driven laterally along a permeable unit called the Blue Unit. Calculations suggest that soon after deposition, lateral flow lowered the effective stress and triggered the submarine landslides that we observe. Later in the evolution of this system, overpressure may have pre-conditioned the slope to failure by earthquakes. Results from IODP Expedition 308 illustrate how pore pressure and sedimentation control the large-scale form of continental margins, how submarine landslides form, and provide strategies for designing stable drilling programs.

Slumping and a sandbar deposit at the Cretaceous-Tertiary boundary in the El Tecolote section (northeastern Mexico): An impact-induced sediment gravity flow

NASA Astrophysics Data System (ADS)

Soria, Ana R.; Liesa, Carlos L.; Mata, Maria Pilar; Arz, José A.; Alegret, Laia; Arenillas, Ignacio; Meléndez, Alfonso

2001-03-01

Slumps affecting uppermost Méndez Formation marls, as well as the spherulitic layer and basal part of the sandy deposits of the Cretaceous-Tertiary (K-T) boundary clastic unit, are described at the new K-T El Tecolote section (northeastern Mexico). These K-T clastic deposits represent sedimentation at middle-bathyal water depths in channel and nonchannel or levee areas of reworked materials coming from environments ranging from outer shelf to shallower slope via a unidirectional, high- to low-density turbidite flow. We emphasize the development and accretion of a lateral bar in a channel area from a surging low-density turbidity current and under a high-flow regime. The slumps discovered on land and the sedimentary processes of the K-T clastic unit reflect destabilization and collapse of the continental margin, support the mechanism of gravity flows in the deep sea, and represent important and extensive evidence for the impact effects in the Gulf of México triggered by the Chicxulub event.

Flow widening through a Darrieus wind turbine - Theory and experiment

NASA Astrophysics Data System (ADS)

Comolet, R.; Harajli, I.; Mercier Des Rochettes, P.; Yeznasni, A.

1982-11-01

A two-dimensional multiple stream tube model is developed for the air flow through a Darrieus wind turbine. The model is configured to account for the widening of the flux tubes as they cross the interior of the actuator disk. Note is made of the lateral broadening of the flow as it moves through the area, leaving a turbulent wake. A relation is defined between the variation in the kinetic energy of the flow and the aerodynamic forces acting on the blades. The global efficiency and the power output of the machine are calculated. Experimental results are reported for a machine equipped with two NACA 0015 blades, each 110 cm long and with a 10 cm chord. The Darrieus had a 1 m diam and was tested in a wind tunnel at wind speeds of 0-18 m/sec. Soap bubbles inflated with He were used for visualization. Power output was found to match prediction. The model is recommended for use in calculating the forces acting on the machine and studying vibration and fatigue causative mechanisms.

Development of an isothermal recombinase polymerase amplification assay for rapid detection of pseudorabies virus.

PubMed

Yang, Yang; Qin, Xiaodong; Zhang, Wei; Li, Zhiyong; Zhang, Shuaijun; Li, Yanmin; Zhang, Zhidong

2017-06-01

Recombinase polymerase amplification assays using real-time fluorescent detection (real-time RPA assay) and lateral flow dipstick (RPA LFD assay) were developed targeting the gD gene of pseudorabies virus (PRV). Both assays were performed at 39 °C within 20 min. The sensitivity of the real-time RPA assay and the RPA LFD assay was 100 copies per reaction and 160 copies per reaction, respectively. Both assays did not detect DNAs from other virus or PRV negative samples. Therefore, the developed RPA assays provide a rapid, simple, sensitive and specific alternative tool for detection of PRV. Copyright © 2017. Published by Elsevier Ltd.

Development and testing of bio-inspired microelectromechanical pressure sensor arrays for increased situational awareness for marine vehicles

NASA Astrophysics Data System (ADS)

Dusek, J.; Kottapalli, A. G. P.; Woo, M. E.; Asadnia, M.; Miao, J.; Lang, J. H.; Triantafyllou, M. S.

2013-01-01

The lateral line found on most species of fish is a sensory organ without analog in humans. Using sensory feedback from the lateral line, fish are able to track prey, school, avoid obstacles, and detect vortical flow structures. Composed of both a superficial component, and a component contained within canals beneath the fish’s skin, the lateral line acts in a similar fashion to an array of differential pressure sensors. In an effort to enhance the situational and environmental awareness of marine vehicles, lateral-line-inspired pressure sensor arrays were developed to mimic the enhanced sensory capabilities observed in fish. Three flexible and waterproof pressure sensor arrays were fabricated for use as a surface-mounted ‘smart skin’ on marine vehicles. Two of the sensor arrays were based around the use of commercially available piezoresistive sensor dies, with innovative packaging schemes to allow for flexibility and underwater operation. The sensor arrays employed liquid crystal polymer and flexible printed circuit board substrates with metallic circuits and silicone encapsulation. The third sensor array employed a novel nanocomposite material set that allowed for the fabrication of a completely flexible sensor array. All three sensors were surface mounted on the curved hull of an autonomous kayak vehicle, and tested in both pool and reservoir environments. Results demonstrated that all three sensors were operational while deployed on the autonomous vehicle, and provided an accurate means for monitoring the vehicle dynamics.

Value for controlling flow of cryogenic fluid

DOEpatents

Knapp, Philip A.

1996-01-01

A valve is provided for accurately controlling the flow of cryogenic fluids such as liquid nitrogen. The valve comprises a combination of disc and needle valves affixed to a valve stem in such a manner that the disc and needle are free to rotate about the stem, but are constrained in lateral and vertical movements. This arrangement provides accurate and precise fluid flow control and positive fluid isolation.

Challenges, developments and perspectives in intermittent ...

EPA Pesticide Factsheets

Although more than half the world's river networks comprise channels that periodically cease to flow and dry [intermittent rivers (IRs)], river ecology was largely developed from and for perennial systems. Ecological knowledge of IRs is rapidly increasing, so there is a need to synthesise this knowledge and deepen ecological understanding.In this Special Issue, we bring together 13 papers spanning observational case studies, field and laboratory experiments and reviews to guide research and management in this productive field of freshwater science. We summarise new developments in IR ecology, identify research gaps and needs, and address how the study of IRs as highly dynamic ecosystems informs ecological understanding more broadly.This series of articles reveals that contemporary IR ecology is a multifaceted and maturing field of research at the interface between aquatic and terrestrial ecology. This research contributes to fresh water and general ecology by testing concepts across a range of topics, including disturbance ecology, metacommunity ecology and coupled aquatic-terrestrial ecosystems.Drying affects flow continuity through time and flow connectivity across longitudinal, lateral and vertical dimensions of space, which aligns well with the recent emphasis of mainstream ecology on meta-system perspectives. Although most articles here focus on the wet phase, there is growing interest in dry phases, and in the terrestrial vegetation and invertebrate assemb

A generalized genetic framework for the development of sinkholes and Karst in Florida, U.S.A.

NASA Astrophysics Data System (ADS)

Beck, Barry F.

1986-03-01

Karst topography in Florida is developed on the Tertiary limestones of the Floridan aquifer Post-depositional diagenesis and solution have made these limestones highly permeable, T=ca. 50,000 m2/d. Zones of megaporosity have formed at unconformities, and dissolution has enlarged joints and fractures Erosion of the overlying clastic Miocene Hawthorn group strata on one flank of a structural arch has exposed the limestone The elevated edge of the Hawthorn cover forms the Cody scarp Ubiquitous solution pipes have previously formed at joint intersections and are now filled Downwashing of the fill deeper into solution cavities in the limestone and subsidence of the overlying unconsolidated sediments causes surface collapse a subsidence doline or sinkhole This process may penetrate up to 60 m of the semi-consolidated Hawthorn cover, as occurred when the Winter Park sinkhole developed Dense clusters of solution pipes may have formed cenotes which are now found on the exposed limestone terrain Groundwater moves laterally as diffuse flow except where input or outflow is concentrated. At sinking streams, vertical shafts, and springs, karst caves have formed, but only the major sinking streams form through-flowing conduit systems Shaft recharge dissipates diffusely. Spring discharge is concentrated from diffuse flow In both cases, conduits taper and merge into a zone of megaporosity

Measurement of turbulent spatial structure and kinetic energy spectrum by exact temporal-to-spatial mapping

NASA Astrophysics Data System (ADS)

Buchhave, Preben; Velte, Clara M.

2017-08-01

We present a method for converting a time record of turbulent velocity measured at a point in a flow to a spatial velocity record consisting of consecutive convection elements. The spatial record allows computation of dynamic statistical moments such as turbulent kinetic wavenumber spectra and spatial structure functions in a way that completely bypasses the need for Taylor's hypothesis. The spatial statistics agree with the classical counterparts, such as the total kinetic energy spectrum, at least for spatial extents up to the Taylor microscale. The requirements for applying the method are access to the instantaneous velocity magnitude, in addition to the desired flow quantity, and a high temporal resolution in comparison to the relevant time scales of the flow. We map, without distortion and bias, notoriously difficult developing turbulent high intensity flows using three main aspects that distinguish these measurements from previous work in the field: (1) The measurements are conducted using laser Doppler anemometry and are therefore not contaminated by directional ambiguity (in contrast to, e.g., frequently employed hot-wire anemometers); (2) the measurement data are extracted using a correctly and transparently functioning processor and are analysed using methods derived from first principles to provide unbiased estimates of the velocity statistics; (3) the exact mapping proposed herein has been applied to the high turbulence intensity flows investigated to avoid the significant distortions caused by Taylor's hypothesis. The method is first confirmed to produce the correct statistics using computer simulations and later applied to measurements in some of the most difficult regions of a round turbulent jet—the non-equilibrium developing region and the outermost parts of the developed jet. The proposed mapping is successfully validated using corresponding directly measured spatial statistics in the fully developed jet, even in the difficult outer regions of the jet where the average convection velocity is negligible and turbulence intensities increase dramatically. The measurements in the developing region reveal interesting features of an incomplete Richardson-Kolmogorov cascade under development.

Regimes of Two-Phase Flow in Short Rectangular Channel

NASA Astrophysics Data System (ADS)

Chinnov, Evgeny A.; Guzanov, Vladimir V.; Cheverda, Vyacheslav; Markovich, Dmitry M.; Kabov, Oleg A.

2009-08-01

Experimental study of two-phase flow in the short rectangular horizontal channel with height 440 μm has been performed. Characteristics of liquid motion inside the channel have been registered and measured by the Laser Induced Fluorescence technique. New information has allowed determining more precisely the characteristics of churn regime and boundaries between different regimes of two-phase flow. It was shown that formation of some two-phase flow regimes and transitions between them are determined by instability of the flow in the lateral parts of the channel.

Cerebral Lateralization and General Intelligence: Gender Differences in a Transcranial Doppler Study

ERIC Educational Resources Information Center

Njemanze, P.C.

2005-01-01

The present study evaluated cerebral lateralization during Raven's progressive matrices (RPM) paradigm in female and male subjects. Bilateral simultaneous transcranial Doppler (TCD) ultrasound was used to measure mean blood flow velocities (MBFV) in the right and left middle cerebral arteries (MCAs) in 24 (15 females and 9 males) right-handed…

Lateral traction of laminar flow between sliding pair with heterogeneous slip/no-slip surface

NASA Astrophysics Data System (ADS)

Wu, Zhenpeng; Zeng, Liangcai; Chen, Xiaolan; Chen, Keying; Ding, Xianzhong

2017-11-01

The problem of shaft axial motion which significantly affects the lubrication performance has been a common phenomenon in journal bearing systems. The existing work involved in the solution of shaft axial motion is also very rare. In this study, we choose to examine the flow between sliding pair in which regard we present a unique heterogeneous surface consisting of a slip zone and a no-slip zone. The results reveal the following points: 1) By appropriately arranging the slip zone to change the angle between the borderline and the moving direction of the upper plate, it is possible to control the direction of the lateral traction in which the liquid film acts on the upper plate. 2) Exponent of the power function of the borderline and aspect ratio of the computational domain are large or small are not conducive to increasing the effect of lateral traction. For the object of this study, the final results of the optimization are shown that the lateral traction can account for 20% of the resistance.

40 CFR 86.078-3 - Abbreviations.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., and for 1985 and Later Model Year New Gasoline Fueled, Natural Gas-Fueled, Liquefied Petroleum Gas... feet per hour. CFV—Critical flow venturi. CFV-CVS—Critical flow venturi—constant volume sampler... pump—constant volume sampler. ppm—parts per million by volume. ppm C—parts per million, carbon. psi...

Loss of unc45a precipitates arteriovenous shunting in the aortic arches

PubMed Central

Anderson, Matthew J.; Pham, Van N.; Vogel, Andreas M.; Weinstein, Brant M.; Roman, Beth L.

2008-01-01

Aortic arch malformations are common congenital disorders that are frequently of unknown etiology. To gain insight into the factors that guide branchial aortic arch development, we examined the process by which these vessels assemble in wild type zebrafish embryos and in kurzschlusstr12 (kus tr12) mutants. In wild type embryos, each branchial aortic arch first appears as an island of angioblasts in the lateral pharyngeal mesoderm, then elaborates by angiogenesis to connect to the lateral dorsal aorta and ventral aorta. In kustr12 mutants, angioblast formation and initial sprouting are normal, but aortic arches 5 and 6 fail to form a lumenized connection to the lateral dorsal aorta. Blood enters these blind-ending vessels from the ventral aorta, distending the arteries and precipitating fusion with an adjacent vein. This arteriovenous malformation (AVM), which shunts nearly all blood directly back to the heart, is not genetically programmed, as its formation correlates with blood flow and aortic arch enlargement. By positional cloning, we have identified a nonsense mutation in unc45a in kustr12 mutants. Our results are the first to ascribe a role for Unc45a, a putative myosin chaperone, in vertebrate development, and identify a novel mechanism by which an AVM can form. PMID:18462713

Applicability of a diffusion model to lateral transport in the terrestrial and lunar exospheres.

NASA Technical Reports Server (NTRS)

Hodges, R. R., Jr.

1972-01-01

Kinetic theory is used to determine a series expansion of the vertical flux of particles in an exosphere in terms of time and space derivatives of particle concentration, exobase velocity, and temperature. For sufficiently large scale variations of these parameters in time and space, the series can be truncated to a form that is similar to a diffusion equation. Owing to this analogy, it is possible to unite the mathematical description of molecular diffusion, which governs thermospheric flow, and the corresponding exospheric equation by using effective transport coefficients which change smoothly with altitude through the transition from thermosphere to exosphere. A new definition of the exobase for lateral flow emerges from the analogy of exospheric and thermospheric diffusion, as the altitude where the horizontal mean free path length equals the mean horizontal extent of ballistic trajectories of the transported gas, as opposed to the scale height of the dominant gas which determines the exobase for escape. It is shown that the approximation of exospheric lateral flow as a diffusion process is applicable to global scale problems concerning terrestrial helium and heavier gases, and lunar gases heavier than helium.

Lateral and subsurface flows impact arctic coastal plain lake water budgets

USGS Publications Warehouse

Koch, Joshua C.

2016-01-01

Arctic thaw lakes are an important source of water for aquatic ecosystems, wildlife, and humans. Many recent studies have observed changes in Arctic surface waters related to climate warming and permafrost thaw; however, explaining the trends and predicting future responses to warming is difficult without a stronger fundamental understanding of Arctic lake water budgets. By measuring and simulating surface and subsurface hydrologic fluxes, this work quantified the water budgets of three lakes with varying levels of seasonal drainage, and tested the hypothesis that lateral and subsurface flows are a major component of the post-snowmelt water budgets. A water budget focused only on post-snowmelt surface water fluxes (stream discharge, precipitation, and evaporation) could not close the budget for two of three lakes, even when uncertainty in input parameters was rigorously considered using a Monte Carlo approach. The water budgets indicated large, positive residuals, consistent with up to 70% of mid-summer inflows entering lakes from lateral fluxes. Lateral inflows and outflows were simulated based on three processes; supra-permafrost subsurface inflows from basin-edge polygonal ground, and exchange between seasonally drained lakes and their drained margins through runoff and evapotranspiration. Measurements and simulations indicate that rapid subsurface flow through highly conductive flowpaths in the polygonal ground can explain the majority of the inflow. Drained lakes were hydrologically connected to marshy areas on the lake margins, receiving water from runoff following precipitation and losing up to 38% of lake efflux to drained margin evapotranspiration. Lateral fluxes can be a major part of Arctic thaw lake water budgets and a major control on summertime lake water levels. Incorporating these dynamics into models will improve our ability to predict lake volume changes, solute fluxes, and habitat availability in the changing Arctic.

Impact of roof height non-uniformity on pollutant transport between a street canyon and intersections.

PubMed

Nosek, Štěpán; Kukačka, Libor; Jurčáková, Klára; Kellnerová, Radka; Jaňour, Zbyněk

2017-08-01

This paper presents an extension of our previous wind-tunnel study (Nosek et al., 2016) in which we highlighted the need for investigation of the removal mechanisms of traffic pollution from all openings of a 3D street canyon. The extension represents the pollution flux (turbulent and advective) measurements at the lateral openings of three different 3D street canyons for the winds perpendicular and oblique to the along-canyon axis. The pollution was simulated by emitting a passive gas (ethane) from a homogeneous ground-level line source positioned along the centreline of the investigated street canyons. The street canyons were formed by courtyard-type buildings of two different regular urban-array models. The first model has a uniform building roof height, while the second model has a non-uniform roof height along each building's wall. The mean flow and concentration fields at the canyons' lateral openings confirm the findings of other studies that the buildings' roof-height variability at the intersections plays an important role in the dispersion of the traffic pollutants within the canyons. For the perpendicular wind, the non-uniform roof-height canyon appreciably removes or entrains the pollutant through its lateral openings, contrary to the uniform canyon, where the pollutant was removed primarily through the top. The analysis of the turbulent mass transport revealed that the coherent flow structures of the lateral momentum transport correlate with the ventilation processes at the lateral openings of all studied canyons. These flow structures coincide at the same areas and hence simultaneously transport the pollutant in opposite directions. Copyright © 2017 Elsevier Ltd. All rights reserved.

CSF Flow in the Brain in the Context of Normal Pressure Hydrocephalus.

PubMed

Bradley, W G

2015-05-01

CSF normally flows back and forth through the aqueduct during the cardiac cycle. During systole, the brain and intracranial vasculature expand and compress the lateral and third ventricles, forcing CSF craniocaudad. During diastole, they contract and flow through the aqueduct reverses. Hyperdynamic CSF flow through the aqueduct is seen when there is ventricular enlargement without cerebral atrophy. Therefore, patients presenting with clinical normal pressure hydrocephalus who have hyperdynamic CSF flow have been found to respond better to ventriculoperitoneal shunting than those with normal or decreased CSF flow. Patients with normal pressure hydrocephalus have also been found to have larger intracranial volumes than sex-matched controls, suggesting that they may have had benign external hydrocephalus as infants. While their arachnoidal granulations clearly have decreased CSF resorptive capacity, it now appears that this is fixed and that the arachnoidal granulations are not merely immature. Such patients appear to develop a parallel pathway for CSF to exit the ventricles through the extracellular space of the brain and the venous side of the glymphatic system. This pathway remains functional until late adulthood when the patient develops deep white matter ischemia, which is characterized histologically by myelin pallor (ie, loss of lipid). The attraction between the bare myelin protein and the CSF increases resistance to the extracellular outflow of CSF, causing it to back up, resulting in hydrocephalus. Thus idiopathic normal pressure hydrocephalus appears to be a "2 hit" disease: benign external hydrocephalus in infancy followed by deep white matter ischemia in late adulthood. © 2015 by American Journal of Neuroradiology.

Development of a lateral flow test to detect metabolic resistance in Bemisia tabaci mediated by CYP6CM1, a cytochrome P450 with broad spectrum catalytic efficiency.

PubMed

Nauen, Ralf; Wölfel, Katharina; Lueke, Bettina; Myridakis, Antonis; Tsakireli, Dimitra; Roditakis, Emmanouil; Tsagkarakou, Anastasia; Stephanou, Euripides; Vontas, John

2015-06-01

Cotton whitefly, Bemisia tabaci (Genn.) (Homoptera: Aleyrodidae) is a major sucking pest in many agricultural and horticultural cropping systems globally. The frequent use of insecticides of different mode of action classes resulted in populations resisting treatments used to keep numbers under economic damage thresholds. Recently it was shown that resistance to neonicotinoids such as imidacloprid is linked to the over-expression of CYP6CM1, a cytochrome P450 monooxygenase detoxifying imidacloprid and other neonicotinoid insecticides when recombinantly expressed in insect cells. However over-expression of CYP6CM1 is also known to confer cross-resistance to pymetrozine, an insecticide not belonging to the chemical class of neonicotinoids. In addition we were able to demonstrate by LC-MS/MS analysis the metabolisation of pyriproxyfen by recombinantly expressed CYP6CM1. Based on our results CYP6CM1 is one of the most versatile detoxification enzymes yet identified in a pest of agricultural importance, as it detoxifies a diverse range of chemical classes used to control whiteflies. Therefore we developed a field-diagnostic antibody-based lateral flow assay which detects CYP6CM1 protein at levels providing resistance to neonicotinoids and other insecticides. The ELISA based test kit can be used as a diagnostic tool to support resistance management strategies based on the alternation of different modes of action of insecticides. Copyright © 2014 Elsevier Inc. All rights reserved.

A Point-of-Need infrared mediated PCR platform with compatible lateral flow strip for HPV detection.

PubMed

Liu, Wenjia; Zhang, Mingfang; Liu, Xiaoyan; Sharma, Alok; Ding, Xianting

2017-10-15

With the increasing need of monitoring the epidemiology of serious infectious diseases, food hygiene, food additives and pesticide residues, it is urgent to develop portable, easy-to-use, inexpensive and rapid molecular diagnostic tools. Herein, we demonstrate a prototype of IR mediated Conducting Oil and CarbOn Nanotube circUlaTing PCR (IR-COCONUT PCR) platform for nucleic acid amplification. The presented platform offers a new solution for miniaturized PCR instruments with non-contact heaters by using conducting oil and carbon nanotube as a medium in IR mediated PCR. This novel platform offers accurate and flexible control of temperature through the integration of PID (proportional-integral-derivative) algorithms to manipulate the duty cycle of the voltage signals of IR LED and a peristaltic pump. The ramping rate of the introduced platform in current study is 1.5°C/s for heating speed and -2.0°C/s for cooling speed. This platform fulfills 30 thermal cycles within 50min which is a match to the conventional bench-top PCR thermo cyclers. For demonstration purpose, human papillomavirus (HPV) patient cervical swab specimens were examined. Downstream lateral flow strip (LFS) was also developed to quantity the PCR products from the IR-COCONUT PCR device within 25min. This PCR platform together with the compatible LFS shows great potential for in-field and Point-of-Need (PoN) testing of genetic or contagious diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

Anatomic and hemodynamic evaluation of renal venous flow in varicocele formation using color Doppler sonography with emphasis on renal vein entrapment syndrome.

PubMed

Unlu, Murat; Orguc, Sebnem; Serter, Selim; Pekindil, Gokhan; Pabuscu, Yuksel

2007-01-01

To investigate the anatomic and hemodynamic properties of testicular venous drainage and its effects on varicocele formation and reflux using color Doppler ultrasound (US) with emphasis on renal vein entrapment syndrome. Upper abdominal and scrotal US examinations of 35 varicocele patients and 35 healthy male subjects were performed in the supine position during rest, during a Valsalva maneuver and in the erect position. The aortomesenteric angle and distance (AMA and AMD, respectively), peak mean velocities (PVs) and diameters of different segments of renal veins, testicular vein diameters and duration of flow inversion were measured. In the varicocele group, the lateral segment of the left renal vein (LRV) had a larger diameter and slower PV, and the medial segment of the LRV had a smaller diameter and faster PV. The diameter of the dominant draining vein correlated with the PV of the medial and lateral segments of the LRV, whereas there was no correlation between the diameter of the dominant draining vein and the diameters of the right renal vein (RRV) and the lateral segment of the LRV or the PV of the RRV. The duration of flow inversion correlated with the diameter and PV of the medial segment of the LRV. No correlation between the diameters and PVs of the RRV and the lateral segment of the LRV was detected. The decreases in the AMA, AMD, diameter of the medial segment of the LRV and PV of the lateral segment of the LRV, and the increases in the PV of the medial segment of the LRV and the diameter of the lateral segment of the LRV in varicocele patients in all positions suggest the entrapment or impingement of the left renal vein between the aorta and the superior mesenteric artery. This has been defined as the "nutcracker phenomenon", which is known to affect varicocele formation.

Development of a high force thermal latch

NASA Technical Reports Server (NTRS)

Nygren, William D.

1995-01-01

This paper describes the preliminary development of a high force thermal latch (HFTL). The HFTL has one moving part which is restrained in the latched position by a low melting temperature or fusible metal alloy. When heated the fusible alloy flows to a receiving chamber and in so doing at first releases the tension load in the latch bolt and later releases the bolt itself. The HFTL can be used in place of pyrotechnically activated spacecraft release devices in those instances where the elimination of both pyrotechnic shock-loading and rapid strain-energy release take precedence over the near instantaneous release offered by ordnance initiated devices.

Visualizing Human Migration Trhough Space and Time

NASA Astrophysics Data System (ADS)

Zambotti, G.; Guan, W.; Gest, J.

2015-07-01

Human migration has been an important activity in human societies since antiquity. Since 1890, approximately three percent of the world's population has lived outside of their country of origin. As globalization intensifies in the modern era, human migration persists even as governments seek to more stringently regulate flows. Understanding this phenomenon, its causes, processes and impacts often starts from measuring and visualizing its spatiotemporal patterns. This study builds a generic online platform for users to interactively visualize human migration through space and time. This entails quickly ingesting human migration data in plain text or tabular format; matching the records with pre-established geographic features such as administrative polygons; symbolizing the migration flow by circular arcs of varying color and weight based on the flow attributes; connecting the centroids of the origin and destination polygons; and allowing the user to select either an origin or a destination feature to display all flows in or out of that feature through time. The method was first developed using ArcGIS Server for world-wide cross-country migration, and later applied to visualizing domestic migration patterns within China between provinces, and between states in the United States, all through multiple years. The technical challenges of this study include simplifying the shapes of features to enhance user interaction, rendering performance and application scalability; enabling the temporal renderers to provide time-based rendering of features and the flow among them; and developing a responsive web design (RWD) application to provide an optimal viewing experience. The platform is available online for the public to use, and the methodology is easily adoptable to visualizing any flow, not only human migration but also the flow of goods, capital, disease, ideology, etc., between multiple origins and destinations across space and time.

Flow Effects on the Flammability Diagrams of Solid Fuels

NASA Technical Reports Server (NTRS)

Cordova, J. L.; Ceamanos, J.; Fernandez-Pello, A. C.; Long, R. T.; Torero, J. L.; Quintiere, J. G.

1997-01-01

A research program is currently underway with the final objective of developing a fundamental understanding of the controlling mechanisms underlying the flammability diagrams of solid combustible materials and their derived fire properties. Given that there is a high possibility of an accidental fire occurring in a space-based facility, understanding the fire properties of materials that will be used in such facilities is of critical importance. With this purpose, the flammability diagrams of the materials, as those produced by the Lateral Ignition and Flame Spread Test (LIFT) apparatus and by a new forced flow device, the Forced Flow Ignition and Flame Spread Test (FIST) apparatus, will be obtained. The specific objective of the program is to apply the new flammability apparatus, which will more accurately reflect the potential ambient conditions of space-based environments, to the characterization of the materials for space applications. This paper presents a parametric study of oxidizer flow effects on the ignition curve of the flammability diagrams of PMMA. The dependence of the ignition delay time on the external radiant flux and either the sample width (LIFT) or the flow velocity (FIST) has been studied. Although preliminary, the results indicate that natural and forced convection flow changes, affect the characteristics of the ignition curves of the flammability diagrams. The major effect on the ignition time appears to be due to convective transfer variations at the fuel surface. At high radiant fluxes or high flow velocities, however, it appears that gas phase processes become increasingly important, affecting the overall ignition delay time. A numerical analysis of the solid fuel heating and pyrolysis has also been developed. The theoretical predictions approximate the experiments well for conditions in which the gas phase induction time is negligible.

Grain-size segregation and levee formation in geophysical mass flows

USGS Publications Warehouse

Johnson, C.G.; Kokelaar, B.P.; Iverson, Richard M.; Logan, M.; LaHusen, R.G.; Gray, J.M.N.T.

2012-01-01

Data from large-scale debris-flow experiments are combined with modeling of particle-size segregation to explain the formation of lateral levees enriched in coarse grains. The experimental flows consisted of 10 m3 of water-saturated sand and gravel, which traveled ∼80 m down a steeply inclined flume before forming an elongated leveed deposit 10 m long on a nearly horizontal runout surface. We measured the surface velocity field and observed the sequence of deposition by seeding tracers onto the flow surface and tracking them in video footage. Levees formed by progressive downslope accretion approximately 3.5 m behind the flow front, which advanced steadily at ∼2 m s−1during most of the runout. Segregation was measured by placing ∼600 coarse tracer pebbles on the bed, which, when entrained into the flow, segregated upwards at ∼6–7.5 cm s−1. When excavated from the deposit these were distributed in a horseshoe-shaped pattern that became increasingly elevated closer to the deposit termination. Although there was clear evidence for inverse grading during the flow, transect sampling revealed that the resulting leveed deposit was strongly graded laterally, with only weak vertical grading. We construct an empirical, three-dimensional velocity field resembling the experimental observations, and use this with a particle-size segregation model to predict the segregation and transport of material through the flow. We infer that coarse material segregates to the flow surface and is transported to the flow front by shear. Within the flow head, coarse material is overridden, then recirculates in spiral trajectories due to size-segregation, before being advected to the flow edges and deposited to form coarse-particle-enriched levees.

Grain-size segregation and levee formation in geophysical mass flows

USGS Publications Warehouse

Johnson, C.G.; Kokelaar, B.P.; Iverson, R.M.; Logan, M.; LaHusen, R.G.; Gray, J.M.N.T.

2012-01-01

Data from large-scale debris-flow experiments are combined with modeling of particle-size segregation to explain the formation of lateral levees enriched in coarse grains. The experimental flows consisted of 10 m3 of water-saturated sand and gravel, which traveled ~80 m down a steeply inclined flume before forming an elongated leveed deposit 10 m long on a nearly horizontal runout surface. We measured the surface velocity field and observed the sequence of deposition by seeding tracers onto the flow surface and tracking them in video footage. Levees formed by progressive downslope accretion approximately 3.5 m behind the flow front, which advanced steadily at ~2 m s-1 during most of the runout. Segregation was measured by placing ~600 coarse tracer pebbles on the bed, which, when entrained into the flow, segregated upwards at ~6–7.5 cm s-1. When excavated from the deposit these were distributed in a horseshoe-shaped pattern that became increasingly elevated closer to the deposit termination. Although there was clear evidence for inverse grading during the flow, transect sampling revealed that the resulting leveed deposit was strongly graded laterally, with only weak vertical grading. We construct an empirical, three-dimensional velocity field resembling the experimental observations, and use this with a particle-size segregation model to predict the segregation and transport of material through the flow. We infer that coarse material segregates to the flow surface and is transported to the flow front by shear. Within the flow head, coarse material is overridden, then recirculates in spiral trajectories due to size-segregation, before being advected to the flow edges and deposited to form coarse-particle-enriched levees.

Plane boundary effects on characteristics of propeller jets

NASA Astrophysics Data System (ADS)

Wei, Maoxing; Chiew, Yee-Meng; Hsieh, Shih-Chun

2017-10-01

The flow properties of a propeller jet in the presence of a plane bed boundary were investigated using the particle image velocimetry technique. Three clearance heights, Z b = 2 D p, D p, and 0.5 D p, where D p = propeller diameter, were used to examine boundary effects on the development of the jet. In each case, the mean flow properties and turbulence characteristics were measured in a larger field of view than those used in past studies. Both the streamwise and transverse flow fields were measured to obtain the three-dimensional characteristics of the propeller jet. Similar to a confined offset jet, the propeller jet also exhibits a wall attachment behavior when it is placed near a plane boundary. As a result, in contrast to its unconfined counterpart, the confined propeller jet features three regions, namely the free jet, impingement and wall jet regions. The study shows that the extent of each region varies under different clearance heights. The development of the mean flow and turbulence characteristics associated with varying clearance heights are compared to illustrate boundary effects in these regions. In the impingement region, the measured transverse flow fields provide new insights on the lateral motions induced by the impingement of the swirling jet. In the wall jet region, observations reveal that the jet behaves like a typical three-dimensional wall jet and its axial velocity profiles show good agreement with the classical wall jet similarity function.

Comparison of Inflation Processes at the 1859 Mauna Loa Flow, HI, and the McCartys Flow Field, NM

NASA Technical Reports Server (NTRS)

Bleacher, Jacob E.; Garry, W. Brent; Zimbelman, James R.; Crumpler, Larry S.

2012-01-01

Basaltic lavas typically form channels or tubes during flow emplacement. However, the importance of sheet flow in the development of basalt ic terrains received recognition over the last 15 years. George Walke r?s research on the 1859 Mauna Loa Flow was published posthumously in 2009. In this paper he discusses the concept of endogenous growth, or inflation, for the distal portion of this otherwise channeldominated lava flow. We used this work as a guide when visiting the 1859 flow to help us better interpret the inflation history of the McCartys flow field in NM. Both well preserved flows display similar clues about the process of inflation. The McCartys lava flow field is among the you ngest (approx.3000 yrs) basaltic lava flows in the continental United States. It was emplaced over slopes of <1 degree, which is similar to the location within the 1859 flow where inflation occurred. Although older than the 1859 flow, the McCartys is located in an arid environ ment and is among the most pristine examples of sheet flow morphologies. At the meter scale the flow surface typically forms smooth, undula ting swales that create a polygonal terrain. The literature for simil ar features includes multiple explanatory hypotheses, original breakouts from adjacent lobes, or inflation related upwarping of crust or sa gging along fractures that enable gas release. It is not clear which of these processes is responsible for polygonal terrains, and it is po ssible that one explanation is not the sole cause of this morphology between all inflated flows. Often, these smooth surfaces within an inflated sheet display lineated surfaces and occasional squeeze-ups alon g swale contacts. We interpret the lineations to preserve original fl ow direction and have begun mapping these orientations to better interpret the emplacement history. At the scale of 10s to 100s of meters t he flow comprises multiple topographic plateaus and depressions. Some depressions display level floors with surfaces as described above, while some are bowl shaped with floors covered in broken lava slabs. Th e boundaries between plateaus and depressions are also typically smoo th, grooved surfaces that have been tilted to angles sometimes approaching vertical. The upper margin of these tilted surfaces displays lar ge cracks, sometimes containing squeeze-ups. The bottom boundary with smooth floored depressions typically shows embayment by younger lavas. It appears that this style of terrain represents the emplacement of an extensive sheet that experiences inflation episodes within prefer red regions where lateral spreading of the sheet is inhibited, thereby forming plateaus. Depressions are often the result of non-inflation and can be clearly identified by lateral squeeze-outs along the pit walls that form when the rising crust exposes the still liquid core of the sheet. Our current efforts are focused on.

Incorporating groundwater flow into the WEPP model

Treesearch

William Elliot; Erin Brooks; Tim Link; Sue Miller

2010-01-01

The water erosion prediction project (WEPP) model is a physically-based hydrology and erosion model. In recent years, the hydrology prediction within the model has been improved for forest watershed modeling by incorporating shallow lateral flow into watershed runoff prediction. This has greatly improved WEPP's hydrologic performance on small watersheds with...

Numerical investigations of solute transport in bimodal porous media under dynamic boundary conditions

NASA Astrophysics Data System (ADS)

Cremer, Clemens; Neuweiler, Insa; Bechtold, Michel; Vanderborght, Jan

2016-04-01

Quantification of flow and solute transport in the shallow subsurface adjacent to the atmosphere is decisive to prevent groundwater pollution and conserve groundwater quality, to develop successful remediation strategies and to understand nutrient cycling. In nature, due to erratic precipitation-evaporation patterns, soil moisture content and related hydraulic conductivity in the vadose zone are not only variable in space but also in time. Flow directions and flow paths locally change between precipitation and evaporation periods. This makes the identification and description of solute transport processes in the vadose zone a complex problem. Recent studies (Lehmann and Or, 2009; Bechtold et al., 2011a) focused on the investigation of upward transport of solutes during evaporation in heterogeneous soil columns, where heterogeneity was introduced by a sharp vertical material interface between two types of sand. Lateral solute transport through the interface in both (lateral) directions was observed at different depths of the investigated soil columns. Following recent approaches, we conduct two-dimensional numerical simulations in a similar setup which is composed of two sands with a sharp vertical material interface. The investigation is broadened from the sole evaporation to combined precipitation-evaporation cycles in order to quantify transport processes resulting from the combined effects of heterogeneous soil structure and dynamic flow conditions. Simulations are performed with a coupled finite volume and random walk particle tracking algorithm (Ippisch et al., 2006; Bechtold et al., 2011b). By comparing scenarios with cyclic boundary conditions and stationary counterparts with the same net flow rate, we found that duration and intensity of precipitation and evaporation periods potentially have an influence on lateral redistribution of solutes and thus leaching rates. Whether or not dynamic boundary conditions lead to significant deviations in the transport behavior depends on the magnitude of the flow rates and hydraulic conductivity curves of the materials. Based on the unsaturated hydraulic conductivity at the intersection point of conductivity curves, we are able to define an estimate of flow rates at which the dynamic of the upper boundary condition significantly alters preferential flow paths through the system. If flow rates are low, with regard to the materials hydraulic conductivity at the intersection point, the influence of dynamic boundary conditions is small. If flow rates are in the range of the unsaturated hydraulic conductivity at intersection, solute is trapped in the fine material during upwards transport, which results in a more pronounced tailing. For flow rates exceeding the intersection conductivity, a redistribution at the soil surface can occur. References: Bechtold, M., S. Haber-Pohlmeier, J. Vanderborght, A. Pohlmeier, T.P.A. Ferré and H. Veerecken. 2011a. Near-surface solute redistribution during evaporation. Geophys. Res. Lett., 38, L17404, doi:10.1029/2011GL048147. Bechtold, M., J. Vanderborght, O. Ippisch and H. Vereecken. 2011b. Efficient random walk particle tracking algorithm for advective dispersive transport in media with discontinuous dispersion coefficients and water contents. Water Resour. Res., 47, W10526, doi: 10.1029/2010WR010267. Ippisch O., H.-J. Vogel and P. Bastian. 2006. Validity limits fort he van Genuchten-Mualem model and implications for parameter estimation and numerical simulation. Adv. Water Resour., 29, 1780-1789, doi: 10.1016/j.advwateres.2005.12.011. Lehmann, P. and D. Or. 2009. Evaporation and capillary coupling across vertical textural contrasts in porous media. Phys. Rev. E, 80, 046318, doi:10.1103/PhysRevE.80.046318.

Design and Calibration of the ARL Mach 3 High Reynolds Number Facility

DTIC Science & Technology

1975-01-01

degrees Rankine. Test rhombus determinations included lateral and longitudinal Mach number distributions and flow angularity measurements. A...43 3. THE TUNNEL EMPTY MACH NUMBER DISTRIBUTION 45 4. THE CENTERLINE RMS MACH NUMBER 46 5. FLOW ANGULARITY MEASUREMENTS 46 6. BLOCKAGE TESTS... Angularity Wedge Scale Drawing of Flow Angularity Cone Normalized Surface Pressure Difference versus Angle of Attack at xp/xr = - 0.690 for po

Investigation of flow turning phenomenon - Effect of upstream and downstream propagation

NASA Astrophysics Data System (ADS)

Baum, Joseph D.

1988-01-01

Upstream acoustic-wave propagation in flow injected laterally through the boundary layer of a tube (simulating the flow in a solid-rocket motor) is investigated analytically. A noniterative linearized-block implicit scheme is used to solve the time-dependent compressible Navier-Stokes equations, and the results are presented in extensive graphs and characterized. Acoustic streaming interaction is shown to be significantly greater for upstream than for downstream propagation.

Numerical study at moderate Reynolds number of peristaltic flow of micropolar fluid through a porous-saturated channel in magnetic field

NASA Astrophysics Data System (ADS)

Ahmed, Bilal; Javed, Tariq; Ali, N.

2018-01-01

This paper analyzes the MHD flow of micropolar fluid induced by peristaltic waves passing through the porous saturated channel at large Reynolds number. The flow model is formulated in the absence of assumptions of lubrication theory which yields the governing equations into a non-linear set of coupled partial differential equations which allows studying the peristaltic mechanism at non-zero Reynolds and wave numbers. The influence of other involved parameters on velocity, stream function and microrotation are discussed through graphs plotted by using Galerkin's finite element method. Besides that, the phenomena of pumping and trapping are also analyzed in the later part of the paper. To ensure the accuracy of the developed code, obtained results are compared with the results available in the literature and found in excellent agreement. It is found that the peristalsis mixing can be enhanced by increasing Hartmann number while it reduces by increasing permeability of the porous medium.

Near-field flow structures about subcritical surface roughness

NASA Astrophysics Data System (ADS)

Doolittle, Charles J.; Drews, Scott D.; Goldstein, David B.

2014-12-01

Laminar flow over a periodic array of cylindrical surface roughness elements is simulated with an immersed boundary spectral method both to validate the method for subsequent studies and to examine how persistent streamwise vortices are introduced by a low Reynolds number roughness element. Direct comparisons are made with prior studies at a roughness-based Reynolds number Rek (=U(k) k/ν) of 205 and a diameter to spanwise spacing ratio d/λ of 1/3. Downstream velocity contours match present and past experiments very well. The shear layer developed over the top of the roughness element produces the downstream velocity deficit. Upstream of the roughness element, the vortex topology is found to be consistent with juncture flow experiments, creating three cores along the recirculation line. Streamtraces stemming from these upstream cores, however, have unexpectedly little effect on the downstream flowfield as lateral divergence of the boundary layer quickly dissipates their vorticity. Long physical relaxation time of the recirculating wake behind the roughness remains a prominent issue for simulating this type of flowfield.