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1

Measuring collective transport by defined numbers of processive and nonprocessive kinesin motors.  

PubMed

Intracellular transport is thought to be achieved by teams of motor proteins bound to a cargo. However, the coordination within a team remains poorly understood as a result of the experimental difficulty in controlling the number and composition of motors. Here, we developed an experimental system that links together defined numbers of motors with defined spacing on a DNA scaffold. By using this system, we linked multiple molecules of two different types of kinesin motors, processive kinesin-1 or nonprocessive Ncd (kinesin-14), in vitro. Both types of kinesins markedly increased their processivities with motor number. Remarkably, despite the poor processivity of individual Ncd motors, the coupling of two Ncd motors enables processive movement for more than 1 ?m along microtubules (MTs). This improvement was further enhanced with decreasing spacing between motors. Force measurements revealed that the force generated by groups of Ncd is additive when two to four Ncd motors work together, which is much larger than that generated by single motors. By contrast, the force of multiple kinesin-1s depends only weakly on motor number. Numerical simulations and single-molecule unbinding measurements suggest that this additive nature of the force exerted by Ncd relies on fast MT binding kinetics and the large drag force of individual Ncd motors. These features would enable small groups of Ncd motors to crosslink MTs while rapidly modulating their force by forming clusters. Thus, our experimental system may provide a platform to study the collective behavior of motor proteins from the bottom up. PMID:23267076

Furuta, Ken'ya; Furuta, Akane; Toyoshima, Yoko Y; Amino, Misako; Oiwa, Kazuhiro; Kojima, Hiroaki

2013-01-01

2

Measuring isotropic subsurface light transport.  

PubMed

Subsurface light transport can affect the visual appearance of materials significantly. Measuring and modeling this phenomenon is crucial for accurately reproducing colors in printing or for rendering translucent objects on displays. In this paper, we propose an apparatus to measure subsurface light transport employing a reference material to cancel out adverse signals that may bias the results. In contrast to other approaches, the setup enables improved focusing on rough surfaces (e.g. uncoated paper). We derive a measurement equation that may be used to deduce the point spread function (PSF) of subsurface light transport. Main contributions are the usage of spectrally-narrowband exchangeable LEDs allowing spectrally-resolved measurements and an approach based on quadratic programming for reconstructing PSFs in the case of isotropic light transport. PMID:24787793

Happel, Kathrin; Dörsam, Edgar; Urban, Philipp

2014-04-21

3

Transportation Optimization with Fuzzy Trapezoidal Numbers Based on Possibility Theory  

PubMed Central

In this paper, a parametric method is introduced to solve fuzzy transportation problem. Considering that parameters of transportation problem have uncertainties, this paper develops a generalized fuzzy transportation problem with fuzzy supply, demand and cost. For simplicity, these parameters are assumed to be fuzzy trapezoidal numbers. Based on possibility theory and consistent with decision-makers' subjectiveness and practical requirements, the fuzzy transportation problem is transformed to a crisp linear transportation problem by defuzzifying fuzzy constraints and objectives with application of fractile and modality approach. Finally, a numerical example is provided to exemplify the application of fuzzy transportation programming and to verify the validity of the proposed methods. PMID:25137239

He, Dayi; Li, Ran; Huang, Qi; Lei, Ping

2014-01-01

4

Transportation optimization with fuzzy trapezoidal numbers based on possibility theory.  

PubMed

In this paper, a parametric method is introduced to solve fuzzy transportation problem. Considering that parameters of transportation problem have uncertainties, this paper develops a generalized fuzzy transportation problem with fuzzy supply, demand and cost. For simplicity, these parameters are assumed to be fuzzy trapezoidal numbers. Based on possibility theory and consistent with decision-makers' subjectiveness and practical requirements, the fuzzy transportation problem is transformed to a crisp linear transportation problem by defuzzifying fuzzy constraints and objectives with application of fractile and modality approach. Finally, a numerical example is provided to exemplify the application of fuzzy transportation programming and to verify the validity of the proposed methods. PMID:25137239

He, Dayi; Li, Ran; Huang, Qi; Lei, Ping

2014-01-01

5

Measuring Distance of Fuzzy Numbers by Trapezoidal Fuzzy Numbers  

NASA Astrophysics Data System (ADS)

Fuzzy numbers and more generally linguistic values are approximate assessments, given by experts and accepted by decision-makers when obtaining value that is more accurate is impossible or unnecessary. Distance between two fuzzy numbers plays an important role in linguistic decision-making. It is reasonable to define a fuzzy distance between fuzzy objects. To achieve this aim, the researcher presents a new distance measure for fuzzy numbers by means of improved centroid distance method. The metric properties are also studied. The advantage is the calculation of the proposed method is far simple than previous approaches.

Hajjari, Tayebeh

2010-11-01

6

Lower Bounds for Measurable Chromatic Numbers  

Microsoft Academic Search

The Lovász theta function provides a lower bound for the chromatic number of finite graphs based on the solution of a semidefinite\\u000a program. In this paper we generalize it so that it gives a lower bound for the measurable chromatic number of distance graphs\\u000a on compact metric spaces.\\u000a \\u000a In particular we consider distance graphs on the unit sphere. There we

Christine Bachoc; Gabriele Nebe; FERNANDO M ´ ARIO DE OLIVEIRA FILHO; Frank Vallentin

2009-01-01

7

TOWARD REAL PERFORMANCE MEASUREMENT: PORTLAND OREGON REGIONAL TRANSPORTATION ARCHIVE LISTING  

E-print Network

TOWARD REAL PERFORMANCE MEASUREMENT: PORTLAND OREGON REGIONAL TRANSPORTATION ARCHIVE LISTING Abstract. Transportation system performance measurement is a key issue for transportation planning and operations, but until recently it has been difficult to incorporate real time intelligent transportation (ITS

Bertini, Robert L.

8

Kinesin-1–driven lipid droplets: Consequences of motor copy number for intracellular transport  

PubMed Central

Summary The microtubule motor Kinesin-1 plays central roles in intracellular transport. It has been widely assumed that many cellular cargos are moved by multiple Kinesins and that cargos with more motors move faster and for longer distances; concrete evidence, however, is sparse. Here we rigorously test these notions using lipid droplets in Drosophila embryos: We first employ antibody inhibition, genetics, biochemistry, and particle tracking to demonstrate that Kinesin-1 mediates plus-end droplet motion. We then measure how variation in Kinesin-1 expression affects the forces driving individual droplets and estimate the number of Kinesins actively engaged per droplet. Unlike in vitro, increased motor number results neither in longer travel distances nor higher velocities. Our data suggest that cargos in vivo can simultaneously engage multiple Kinesins and that transport properties are largely unaffected by variation in motor number. Apparently, higher-order regulatory mechanisms rather than motor number per se dominate cargo transport in vivo. PMID:19070579

Shubeita, G. T.; Tran, S. L.; Xu, J.; Vershinin, M.; Cermelli, S.; Cotton, S. L.; Welte, M. A.; Gross, S. P.

2009-01-01

9

Low Peclet number mass and momentum transport in microcavities  

NASA Astrophysics Data System (ADS)

For the informed design of microfluidic devices, it is important to understand transport phenomena at the microscale. This letter outlines an analytically driven approach to the design of rectangular microcavities extending perpendicular to a perfusion microchannel for applications that may include microfluidic cell culture devices. We present equations to estimate the transition from advection- to diffusion-dominant transport inside cavities as a function of the geometry and flow conditions. We also estimate the time required for molecules, such as nutrients or drugs, to travel from the microchannel to a given length into the cavity. These analytical predictions can facilitate the rational design of microfluidic devices to optimize and maintain long-term, low Peclet number environments with minimal fluid shear stress.

Yew, A. G.; Pinero, D.; Hsieh, A. H.; Atencia, J.

2013-02-01

10

Hyperreactive platelet phenotypes: relationship to altered serotonin transporter number, transport kinetics and intrinsic response to adrenergic co-stimulation.  

PubMed

The mechanism underlying a hyperreactive platelet phenotype remains unknown. Since serotonin has been shown to influence platelet biology and atherothrombosis, we sought to investigate the association of platelet serotonin transporter number, binding affinity, and uptake kinetics with platelet aggregation. A total of 542 healthy volunteers had light transmittance platelet aggregometry measured in response to varying concentrations of epinephrine, serotonin, epinephrine plus serotonin, ADP and collagen. Transporter-dependent serotonin uptake rate was determined (Vmax), as were serotonin transporter number (Bmax) and binding affinity (Kd) using 3H paroxetine binding in a homologous displacement assay, nonlinear regression and validated algorithms for kinetic modelling. Stimulation with submaximal (2?M) epinephrine concentration elicited a distinct, bimodal pattern of platelet aggregation in this population. In contrast, subjects exhibited minimal aggregation in response to serotonin alone. Co-stimulation with submaximal epinephrine and serotonin induced platelet aggregation to a level beyond that observed with either agonist alone and maintained a bimodal response distribution. Subjects with heightened (>60%) platelet aggregation to both epinephrine alone and epinephrine plus serotonin exhibited increased platelet serotonin uptake, and transporter number and affinity. In a population of healthy subjects, co-stimulation with submaximal concentrations of epinephrine and serotonin identifies a subset of individuals with a hyperreactive platelet aggregation profile that is associated with changes in platelet serotonin function. PMID:23223800

Berger, Jeffrey S; Becker, Richard C; Kuhn, Cynthia; Helms, Michael J; Ortel, Thomas L; Williams, Redford

2013-01-01

11

Constituent quark scaling violation due to baryon number transport  

SciTech Connect

In ultrarelativistic heavy-ion collisions at {radical}s{sub NN} {approx} 200 GeV, the azimuthal emission anisotropy of hadrons with low and intermediate transverse momentum (p{sub T} {approx}< 4 GeV/c) displays an intriguing scaling. In particular, the baryon (meson) emission patterns are consistent with a scenario in which a bulk medium of flowing quarks coalesces into three-quark (two-quark) 'bags.' While a full understanding of this number-of-constituent-quark (NCQ) scaling remains elusive, it is suggestive of a thermalized bulk system characterized by colored dynamical degrees of freedom - a quark-gluon plasma (QGP). In this scenario, one expects the scaling to break down as the central energy density is reduced below the QGP formation threshold; for this reason, NCQ-scaling violation searches are of interest in the energy scan program at the Relativistic Heavy Ion Collider. However, as {radical}s{sub NN} is reduced, it is not only the initial energy density that changes; there is also an increase in the net baryon number at midrapidity, as stopping transports entrance-channel partons to midrapidity. This phenomenon can result in violations of simple NCQ scaling. Still in the context of the quark coalescence model, we describe a specific pattern for the breakdown of the scaling that includes different flow strengths for particles and their antipartners. Related complications in the search for recently suggested exotic phenomena are also discussed.

Dunlop J. C.; Lisa, M.A., Sorensen, P.

2011-10-31

12

41 CFR 102-118.170 - Will GSA continue to maintain a centralized numbering system for Government transportation...  

Code of Federal Regulations, 2014 CFR

...centralized numbering system for Government transportation documents? 102-118.170 Section 102-118...Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT Ordering and Paying...

2014-01-01

13

Measuring Argumentative Reasoning: What's behind the Numbers?  

ERIC Educational Resources Information Center

The aim of this paper is to develop a more thorough, empirically-based understanding of the differences in measurement of written argumentation when alternative scoring frameworks are employed. Reflective compositions of 127 elementary school children were analyzed using analytic and holistic scales. The scales were derived from Argument Schema…

Reznitskaya, Alina; Kuo, Li-jen; Glina, Monica; Anderson, Richard C.

2009-01-01

14

VARIABILITY IN MEASURED BEDLOAD-TRANSPORT RATES.  

USGS Publications Warehouse

During a four-day period of nearly constant water discharge, four sets of consecutively collected bedload samples, ranging from 43 to 120 samples, were obtained at the same cross channel location using a standard 65-pound Helley-Smith bedload sampler. When the measured transport rates are converted to dimensionless rates and plotted as cumulative frequency distributions, they show good agreement with a theoretical probability distribution function of rates derived for the case of ripples on dunes. The distributions show that during constant water discharge individual measured rates at a fixed point vary from near zero to four times the mean rate, and 60 percent of the sampled rates will be less than the mean.

Carey, William P.

1985-01-01

15

Session Number XXXX Using an Intelligent Transportation System Data Archive to Improve  

E-print Network

Session Number XXXX Using an Intelligent Transportation System Data Archive to Improve Student Abstract The Portland, Oregon regional intelligent transportation systems (ITS) data archive (known of Transportation (ODOT) and Portland State University (PSU). The data archive receives 20-second data from the 436

Bertini, Robert L.

16

Quantum nondemolition measurement of small photon numbers using stored light  

NASA Astrophysics Data System (ADS)

We propose a scheme for realizing a quantum nondemolition (QND) measurement of a small number of optical photons. Our scheme has two stages: First, we couple a propagating light pulse with fixed photon number to a trapped cold atomic gas within a cavity, such that the pulse is stored within a collective polariton mode. Second, a small-photon-number measurement is engineered by monitoring the cavity-transmission spectrum. Since the polariton mode profile is preserved during the process of detecting the spectrum, photon-number QND measurements could be achieved by retrieving the light pulse from the polariton mode. We also discuss a method which uses QND measurements to generate small-photon Fock states.

Liang, L.; Lin, G. W.; Hao, Y. M.; Niu, Y. P.; Gong, S. Q.

2014-11-01

17

TRANSPORT PROPERTY MEASUREMENTS OF HFC-236EA  

EPA Science Inventory

The report gives results of an evaluation of transport properties of 1,1,1,2,3,3,-hexafluoropropane (HFC-236ea), with liquid viscosity and thermal conductivity being the two main transport properties of interest. In addition, the specific heat and density of refrigerant/lubrican...

18

TRANSPORT PROPERTY MEASUREMENTS OF HFC-236EA  

EPA Science Inventory

The report gives results of an evaluation of transport properties of 1, 1, 1, 2, 3, 3-hexafluoropropane (HFC-236ea), with liquid viscosity and thermal conductivity being the two main transport properties of interest. In addition, the specific heat and density of refrigerant/lubri...

19

Bacterial Abundance Measure bacterial numbers and mass per unit volume.  

E-print Network

.37 1021 l oceans-1 Crude estimate of element fluxes (x: bacterial biomass) · Growth rate: G = xBacterial Abundance Objective · Measure bacterial numbers and mass per unit volume. · Note, we). · Plate (or viable) count (Today). · Direct count. (Thursday). #12;Why do we want to measure bacterial

Vallino, Joseph J.

20

Bacterial Abundance Measure bacterial numbers and mass per unit volume.  

E-print Network

.37 � 1021 l oceans-1 Crude estimate of element fluxes (x: bacterial biomass) · Growth rate: G = µx; µBacterial Abundance Objective · Measure bacterial numbers and mass per unit volume. · Note, we). · Plate (or viable) count (Today). · Direct count. (Thursday). #12;Why do we want to measure bacterial

Vallino, Joseph J.

21

First measurements of aerosol optical depth and Angstrom exponent number from AERONET's Kuching site  

NASA Astrophysics Data System (ADS)

We report our first measurements, over the 2011 dry season period, of aerosol optical depth, Angstrom exponent number and its fine mode counterpart obtained from photometric measurements at AERONET's newest site located at the city of Kuching, Sarawak, East Malaysia. This site was set up as part of the collaborative efforts of the Seven South East Asian Studies (7SEAS) regional aerosol measurements initiative. Located at the converging zone between peninsular Malaysia and the land masses of Sumatra, Borneo, Java and Sulawesi, this site is expected to provide first hand evidence about the physical and optical characteristics of the regional aerosol environment, specially during the biomass burning months. Moreover, given its relative proximity to our Singapore radiation measurement super-site, Kuching is expected to provide further insight on aerosol transport pathways caused by seasonal winds transporting smoke to other parts of the maritime continent and the South Asia region.

Salinas, Santo V.; Chew, Boon N.; Mohamad, M.; Mahmud, M.; Liew, Soo C.

2013-10-01

22

Meanings for Fraction as Number-Measure by Exploring the Number Line  

ERIC Educational Resources Information Center

This paper reports on a case-study design experiment in the domain of fraction as number-measure. We designed and implemented a set of exploratory tasks concerning comparison and ordering of fractions as well as operations with fractions. Two groups of 12-year-old students worked collaboratively using paper and pencil as well as a specially…

Psycharis, Giorgos; Latsi, Maria; Kynigos, Chronis

2009-01-01

23

Lagrangian Transport Model Forecasts as a Useful Tool for Predicting Intercontinental Pollution Transport During Measurement Campaigns  

Microsoft Academic Search

Summary In this study, the Lagrangian tracer transport model FLEXPART is shown to be a useful forecasting tool for the flight planning during aircraft measurement campaigns. The advantages of this model are that it requires only a short computation time, has a finer spatial resolution and does not suffer numerical diffusion compared to chemistry transport models (CTMs). It is a

Caroline Forster; A. Stohl; H. Huntrieser; O. Cooper; S. Eckhardt; P. James; J. Heland; H. Schlager; F. Arnold; H. Aufmhoff; N. Spichtinger; E. Dunlea; D. K. Nicks; J. S. Holloway; G. Hübler; D. D. Parrish; T. Ryerson

24

A device for measuring sonic velocity and compressor Mach number  

NASA Technical Reports Server (NTRS)

A device has been developed which measures the velocity of sound in fluids at stagnation and is especially adaptable to turbine and compressor testing for which the constituency of the working fluid may be in doubt. By utilizing the shaft frequency of a rotary compressor, the instrument can also be used to provide a direct measurement of the compressor Mach number (ratio of blade-tip velocity to inlet velocity of sound at stagnation). A Helmholtz resonator is employed in the measurement of the sound velocity. Viscous effects in the orifice of the Helmholtz resonator are shown to be important and can be taken into account with the help of a parameter obtained from Stokes solution of the flow near an oscillating wall. This parameter includes the kinematic viscosity of the fluid and the frequency of sound in the resonator. When these effects are recognized, the resonator can be calibrated to measure velocity of sound or compressor Mach number to an accuracy of better than 0.5 percent.

Huber, Paul W; Kantrowitz, Arthur

1947-01-01

25

Transported acid aerosols measured in southern Ontario  

NASA Astrophysics Data System (ADS)

During the period 29 June 1986-9 August 1986, a field health study assessing the acute health effects of air pollutants on children was conducted at a summer girls' camp on the northern shore of Lake Erie in SW Ontario. Continuous air pollution measurements of SO 2, O 3, NO x, particulate sulfates, light scattering, and meteorological measurements including temperature, dew point, and wind speed and direction were made. Twelve-hour integrated samples of size fractioned particles were also obtained using dichotomous samplers and Harvard impactors equipped with an ammonia denuder for subsequent hydrogen ion determination. Particulate samples were analyzed for trace elements by X-ray fluorescence and Neutron Activation, and for organic and elemental carbon by a thermal/optical technique. The measured aerosol was periodically very acidic with observed 12-h averaged H + concentrations in the range < 10-560 nmoles m -3. The aerosol H + appeared to represent the net strong acidity after H 2SO 4 reaction with NH 3(g). Average daytime concentrations were higher than night-time for aerosol H +, sulfate, fine mass and ozone. Prolonged episodes of atmospheric acidity, sulfate, and ozone were associated with air masses arriving at the measurement site from the west and from the southwest over Lake Erie. Sulfate concentrations measured at the lakeshore camp were more than twice those measured at inland sites during extreme pollution episodes. The concentration gradient observed with onshore flow was potentially due to enhanced deposition near the lakeshore caused by discontinuities in the meteorological fields in this region.

Keeler, Gerald J.; Spengler, John D.; Koutrakis, Petros; Allen, George A.; Raizenne, Mark; Stern, Bonnie

26

Thermal Transport Measurements of Individual Multiwalled Nanotubes  

Microsoft Academic Search

The thermal conductivity and thermoelectric power of a single carbon nanotube were measured using a microfabricated suspended device. The observed thermal conductivity is more than 3000 W\\/K m at room temperature, which is 2 orders of magnitude higher than the estimation from previous experiments that used macroscopic mat samples. The temperature dependence of the thermal conductivity of nanotubes exhibits a

P. Kim; L. Shi; A. Majumdar; P. L. McEuen

2001-01-01

27

76 FR 41859 - Waiver Petition Docket Numbers FRA-2011-0002, CSX Transportation Railroad, and FRA-2004-17565...  

Federal Register 2010, 2011, 2012, 2013, 2014

...DEPARTMENT OF TRANSPORTATION Federal Railroad Administration Waiver Petition Docket Numbers FRA-2011-0002, CSX Transportation Railroad, and FRA-2004-17565, Union Pacific Railroad; Public Hearing On February 23,...

2011-07-15

28

Estimating the theoretical semivariogram from finite numbers of measurements  

USGS Publications Warehouse

We investigate from a theoretical basis the impacts of the number, location, and correlation among measurement points on the quality of an estimate of the semivariogram. The unbiased nature of the semivariogram estimator ??/(r) is first established for a general random process Z(x). The variance of ??z(r) is then derived as a function of the sampling parameters (the number of measurements and their locations). In applying this function to the case of estimating the semivariograms of the transmissivity and the hydraulic head field, it is shown that the estimation error depends on the number of the data pairs, the correlation among the data pairs (which, in turn, are determined by the form of the underlying semivariogram ??(r)), the relative locations of the data pairs, and the separation distance at which the semivariogram is to be estimated. Thus design of an optimal sampling program for semivariogram estimation should include consideration of each of these factors. Further, the function derived for the variance of ??z(r) is useful in determining the reliability of a semivariogram developed from a previously established sampling design.

Zheng, L.; Silliman, S.E.

2000-01-01

29

Monitoring quantum transport: Backaction and measurement correlations  

NASA Astrophysics Data System (ADS)

We investigate a tunnel contact coupled to a double quantum dot (DQD) and employed as a charge monitor for the latter. We consider both the classical limit and the quantum regime. In the classical case, we derive measurement correlations from conditional probabilities, yielding quantitative statements about the parameter regime in which the detection scheme works well. Moreover, we demonstrate that not only the DQD occupation but also the corresponding current may strongly correlate with the detector current. The quantum-mechanical solution, obtained with a Bloch-Redfield master equation, shows that the backaction of the measurement tends to localize the DQD electrons, and thus significantly reduces the DQD current. Moreover, it provides the effective parameters of the classical treatment. It turns out that already the classical description is adequate for most operating regimes.

Hussein, Robert; Gómez-García, Jorge; Kohler, Sigmund

2014-10-01

30

Effects of Lewis number on turbulent kinetic energy transport in premixed flames  

NASA Astrophysics Data System (ADS)

The effects of global Lewis number on the statistical behaviour of turbulent kinetic energy transport in turbulent premixed flames are analysed using three-dimensional direct numerical simulation (DNS) data for freely propagating statistically planar flames with Lewis number ranging from 0.34 to 1.2. For flames with Lewis number significantly smaller than unity, it is observed that the turbulent kinetic energy is significantly augmented within the flame brush due to flame-generated turbulence. In these flames, it is demonstrated that effects of the mean pressure gradient and pressure dilatation are sufficient to overcome the effects of viscous dissipation. By contrast, for flames with Lewis number close to unity, it is found that the turbulent kinetic energy decays monotonically through the flame brush. In these flames, the effects of the mean pressure gradient and pressure dilatation terms are relatively much weaker than those of viscous dissipation. The modelling of the various unclosed terms of the turbulent kinetic energy transport equation has been analysed in detail. The predictions of existing models are compared with corresponding quantities extracted from DNS data. Based on this a-priori DNS assessment, either appropriate models are identified or new models are proposed where necessary. It is shown that the turbulent flux of turbulent kinetic energy exhibits counter-gradient transport for the low Lewis number flames where the turbulent scalar flux is also counter-gradient in nature. However, for flames with Lewis number close to unity, the turbulent flux of turbulent kinetic energy exhibits predominantly gradient type transport. A new model has been proposed for the flux of turbulent kinetic energy in premixed flames and is found to capture the qualitative and quantitative behaviour obtained from DNS data for all the different Lewis numbers considered.

Chakraborty, Nilanjan; Katragadda, Mohit; Cant, R. S.

2011-07-01

31

An application of uncertain numbers in radio frequency power measurement  

NASA Astrophysics Data System (ADS)

The uncertain-numbers method (Hall B D 2006 Metrologia 43 L56-61) is an alternative computational procedure to the Law of Propagation of Uncertainty (LPU) described in the Guide to the Expression of Uncertainty in Measurement. One advantage of the method is that data processing can be carried out in an arbitrary series of steps and much of the mathematical analysis normally associated with the LPU can be automated by software. This has applications for measuring systems, which are modular in design and use internal data processing to apply corrections to raw data. Several scenarios involving radio frequency power measurements are used to illustrate the new method in this context. The scenarios show something of the difficulty inherent in calculating uncertainty for modern measurement systems and in particular highlight the occurrence of systematic errors arising from internal instrument correction factors. Such errors introduce correlation to a series of measurements and must be handled with care when functions of results, such as means, differences and ratios, are required.

Hall, B. D.

2009-06-01

32

Measurement of magnetic fluctuation induced energy transport  

SciTech Connect

The local electron energy flux produced by magnetic fluctuations has been measured directly in the MST reversed field pinch (over the radial range r/a > 0.75). The flux, produced by electrons traveling parallel to a fluctuating magnetic field, is obtained from correlation between the fluctuations in the parallel heat flux and the radial magnetic field. The fluctuation induced flux is large (100 kW/cm{sup 2}) in the ``core`` (r/a < 0.85) and small (< 10--30 kW/cm{sup 2}) in the edge.

Fiksel, G.; Prager, S.C.; Shen, W.; Stoneking, M.

1993-11-01

33

A precision measurement of the number of neutrino species  

Microsoft Academic Search

We have measured the cross section for e+e--->hadrons over the center of mass energy range of the Z0 peak, from 88.22 to 95.03 GeV. We determine the Z0 mass Mz=91.164+\\/-0.013 (experiment) +\\/-0.030 (LEP) GeV. Within the framework of the standard model we determine the invisible width, Gammainvisible=0.502+\\/-0.018 GeV, and the number of light neutrino species, Nnu=3.01+\\/-0.11. We exclude the existence

B. Adeva; O. Adriani; M. Aguilar-Benitez; H. Akbari; J. Alcaraz; A. Aloisio; G. Alverson; M. G. Alviggi; Q. An; H. Anderhub; A. L. Anderson; V. P. Andreev; T. Angelov; L. Antonov; D. Antreasyan; P. Arce; A. Arefiev; T. Azemoon; T. Aziz; P. V. K. S. Baba; P. Bagnaia; J. A. Bakken; L. Baksay; R. C. Ball; S. Banerjee; J. Bao; L. Barone; A. Bay; U. Becker; J. Behrens; S. Beingessner; Gy. L. Bencze; J. Berdugo; P. Berges; B. Bertucci; B. L. Betev; A. Biland; R. Bizzarri; J. J. Blaising; P. Blömeke; B. Blumenfeld; Gerjan J Bobbink; M. Bocciolini; W. Böhlen; A. Böhm; T. Böhringer; B. Borgia; D. Bourilkov; Maurice Bourquin; D. Boutigny; J. G. Branson; I. C. Brock; F. Bruyant; C. Buisson; A T Bujak; J. D. Burger; J. P. Burq; J K Busenitz; X. D. Cai; C. Camps; M. Capell; F. Carbonara; F. Carminati; A. M. Cartacci; M Cerrada-Canales; F. Cesaroni; Y. H. Chang; U. K. Chaturvedi; M. Chermarin; A. Chen; C. Chen; G. M. Chen; H. F. Chen; H. S. Chen; M L Chen; G. Chiefari; C Civinini; I. Clare; R. Clare; G. Coignet; N. Colino; V. Commichau; G. Conforto; A. Contin; F. Crijns; X. Y. Cui; T. S. Dai; R. D'Alessandro; R. de Asmundis; A. Degré; K. Deiters; E. Dénes; P. Denes; F. Denotaristefani; M. Dhina; D. Dibitonto; M. Diemoz; F. Diez-Hedo; H. R. Dimitrov; C. Dionisi; F. Dittus; R. Dolin; E. Drago; T. Driever; D. Duchesneau; P. Duinker; I. Duran; H. El Mamouni; A. Engler; F. J. Eppling; F. C. Erné; P. Extermann; R. Fabbretti; G. Faber; S. Falciano; Q. Fan; S. J. Fan; M. Fabre; J Fehlmann; H. Fenker; T. Ferguson; G. Fernandez; F. Ferroni; H. Fesefeldt; J. Field; G. Finocchiaro; P. H. Fisher; G. Forconi; T. Foreman; K. Freudenreich; W. Friebel; M. Fukushima; M. Gailloud; Yu. Galaktionov; E. Gallo; S. N. Ganguli; P. Garcia-Abia; S Gentile; M Glaubman; S. Goldfarb; Z. F. Gong; E. Gonzalez; A. Gordeev; P. Göttlicher; D. Goujon; C. Goy; G. Gratta; A. Grimes; C. Grinnell; M. Gruenewald; M. Guanziroli; A. Gurtu; L. J. Gutay; H. Haan; S. Hancke; K. Hangarter; M. Harris; A. Hasan; C. F. He; A. Heavey; T. Hebbeker; M. Hebert; G. Herten; U. Herten; A. Hervé; K. Hilgers; H Hoorani; L. S. Hsu; G Q Hu; B. Ille; M. M. Ilyas; V. Innocente; E. Isiksal; E. Jagel; B. N. Jin; L. W. Jones; P. Kaaret; R. A. Khan; Yu. Kamyshkov; D. Kaplan; Y. Karyotakis; M. Kaur; S. Khokhar; V. Khoze; D. Kirkby; W. Kittel; A. Klimentov; A. C. König; O. Kornadt; V. Koutsenko; R. W. Kraemer; T. Kramer; V. R. Krastev; W. Krenz; J. Krizmanic; A. Kuhn; K. S. Kumar; V. Kumar; A. Kunin; S. Kwan; A. van Laak; V. Lalieu; G. Landi; K. Lanius; W. Lange; D. Lanske; S. Lanzano; P Lecomte; P. Lecoq; P. Le Coultre; I. Leedom; J. M. Le Goff; A. Leike; L. Leistam; R. Leiste; J. Lettry; P. M. Levchenko; X. Leytens; C. Li; H. T. Li; J. F. Li; L. Li; P. J. Li; Q. Li; X. G. Li; J. Y. Liao; Z. Y. Lin; F. L. Linde; D. Linnhofer; R. Liu; Y. Liu; W. Lohmann; S. Lökös; E. Longo; Y. S. Lu; J. M. Lubbers; K. Lübelsmeyer; C. Luci; D. Luckey; L. Ludovici; X. Lue; L. Luminari; W. G. Ma; M. MacDermott; R. Magahiz; M. Maire; P. K. Malhotra; R. Malik; A. Malinin; C. Maña; D. N. Mao; Y. F. Mao; M. Maolinbay; P. Marchesini; A. Marchionni; J. P. Martin; L. Martinez; F. Marzano; G. G. G. Massaro; T. Matsuda; K. Mazumdar; P. McBride; T. McMahon; D. McNally; Th. Meinholz; M. Merk; L. Merola; M. Meschini; W. J. Metzger; Y. Mi; M. Micke; U. Micke; G. B. Mills; Y. Mir; G. Mirabelli; J. Mnich; M. Möller; L. Montanet; B. Monteleoni; G. Morand; R. Morand; S. Morganti; V. Morgunov; R. Mount; E. Nagy; M. Napolitano; H. Newman; M. A. Niaz; L. Niessen; W. D. Nowak; H. Nowak; S. Nowak; D. Pandoulas; G. Paternoster; S. Patricelli; Y. J. Pei; D. Perret-Gallix; J. Perrier; A. Pevsner; M. Pieri; P. A. Piroué; V. Plyaskin; M. Pohl; V Pozhidaev; N. Produit; J. M. Qian; K. N. Qureshi; R. Raghavan; G. Rahal-Callot; P A Razis; K. Read; D. Ren; Z. Ren; S. Reucroft; Tord Riemann; C. Rippich; H. A. Rizvi; B. P. Roe; M. Röhner; S. Röhner; Th. Rombach; L. Romero; J. Rose; S. Rosier-Lees; R. Rosmalen; Ph. Rosselet; Juan Antonio Rubio; W. Ruckstuhl; H. Rykaczewski; M. Sachwitz; J. Salicio; G. Sartorelli; G. Sauvage; A. Savin; V Shchegelskii; D. Schmitz; P. Schmitz; M. Schneegans; M. Schöntag; Herwig Franz Schopper; D. J. Schotanus; H. J. Schreiber; R. Schulte; K. Schultze; J. Schütte; J. Schwenke; G. Schwering; C. Sciacca; R. Sehgal; P. G. Seiler; J. C. Sens; I. Sheer; V. Shevchenko; S. Shevchenko; X. R. Shi; K. Shmakov; V. Shoutko; E. Shumilov; N. Smirnov; A. Sopczak; C. Souyri; C. Spartiotis; T. Spickermann; B. Spiess; P. Spillantini; R. Starosta; M. Steuer; D. P. Stickland; B. Stöhr; H. Stone; K. Strauch; B. C. Stringfellow; K. Sudhakar; G. Sultanov; R. L. Summer; H. Suter; R. B. Sutton; J. D. Swain; A. A. Syed; X. W. Tang; E. Tarkovsky; J. M. Thenard; C. Timmermans; Samuel C. C. Ting; S. M. Ting; Y. P. Tong; F. Tonisch; M. Tonutti; S. C. Tonwar; J. Tòth; G. Trowitzsch; K. L. Tung

1990-01-01

34

Gasificaton Transport: A Multiphase CFD Approach & Measurements  

SciTech Connect

The objective of this project was to develop predictive theories for the dispersion and mass transfer coefficients and to measure them in the turbulent fluidization regime, using existing facilities. A second objective was to use our multiphase CFD tools to suggest optimized gasifier designs consistent with aims of Future Gen. We have shown that the kinetic theory based CFD codes correctly compute: (1) Dispersion coefficients; and (2) Mass transfer coefficients. Hence, the kinetic theory based CFD codes can be used for fluidized bed reactor design without any such inputs. We have also suggested a new energy efficient method of gasifying coal and producing electricity using a molten carbonate fuel cell. The principal product of this new scheme is carbon dioxide which can be converted into useful products such as marble, as is done very slowly in nature. We believe this scheme is a lot better than the canceled FutureGen, since the carbon dioxide is safely sequestered.

Dimitri Gidaspow; Veeraya Jiradilok; Mayank Kashyap; Benjapon Chalermsinsuwan

2009-02-14

35

Automatic trajectory measurement of large numbers of crowded objects  

NASA Astrophysics Data System (ADS)

Complex motion patterns of natural systems, such as fish schools, bird flocks, and cell groups, have attracted great attention from scientists for years. Trajectory measurement of individuals is vital for quantitative and high-throughput study of their collective behaviors. However, such data are rare mainly due to the challenges of detection and tracking of large numbers of objects with similar visual features and frequent occlusions. We present an automatic and effective framework to measure trajectories of large numbers of crowded oval-shaped objects, such as fish and cells. We first use a novel dual ellipse locator to detect the coarse position of each individual and then propose a variance minimization active contour method to obtain the optimal segmentation results. For tracking, cost matrix of assignment between consecutive frames is trainable via a random forest classifier with many spatial, texture, and shape features. The optimal trajectories are found for the whole image sequence by solving two linear assignment problems. We evaluate the proposed method on many challenging data sets.

Li, Hui; Liu, Ye; Chen, Yan Qiu

2013-06-01

36

Measurement of particle transport coefficients on Alcator C-Mod  

SciTech Connect

The goal of this thesis was to study the behavior of the plasma transport during the divertor detachment in order to explain the central electron density rise. The measurement of particle transport coefficients requires sophisticated diagnostic tools. A two color interferometer system was developed and installed on Alcator C-Mod to measure the electron density with high spatial ({approx} 2 cm) and high temporal ({le} 1.0 ms) resolution. The system consists of 10 CO{sub 2} (10.6 {mu}m) and 4 HeNe (.6328 {mu}m) chords that are used to measure the line integrated density to within 0.08 CO{sub 2} degrees or 2.3 {times} 10{sup 16}m{sup {minus}2} theoretically. Using the two color interferometer, a series of gas puffing experiments were conducted. The density was varied above and below the threshold density for detachment at a constant magnetic field and plasma current. Using a gas modulation technique, the particle diffusion, D, and the convective velocity, V, were determined. Profiles were inverted using a SVD inversion and the transport coefficients were extracted with a time regression analysis and a transport simulation analysis. Results from each analysis were in good agreement. Measured profiles of the coefficients increased with the radius and the values were consistent with measurements from other experiments. The values exceeded neoclassical predictions by a factor of 10. The profiles also exhibited an inverse dependence with plasma density. The scaling of both attached and detached plasmas agreed well with this inverse scaling. This result and the lack of change in the energy and impurity transport indicate that there was no change in the underlying transport processes after detachment.

Luke, T.C.T.

1994-10-01

37

Modeling source contributions to submicron particle number concentrations measured in Rochester, New York  

SciTech Connect

An advanced receptor model was used to elicit source information based on ambient submicron (0.01-0.47 {mu}m) particle number concentrations, gaseous species, and meteorological variables measured at the New York State Department of Environmental Conservation central monitoring site in Rochester, NY. Four seasonal data sets (winter, spring, summer, and fall) were independently investigated. A total of ten different sources were identified, including two traffic factors, two nucleation factors, industrial emissions, residential/commercial heating, secondary nitrate, secondary sulfate, ozone-rich secondary aerosol, and regionally transported aerosol. The resolved sources were generally characterized by similar number modes for either winter, spring, summer or fall. The size distributions for nucleation were dominated by the smallest particles ({lt}10-30 nm) that gradually grew to larger sizes as could be seen by observing the volume profiles. In addition, the nucleation factors were closely linked to traffic rush hours suggesting that cooling of tail-pipe emissions may have induced nucleation activity in the vicinity of the highways. Industrial emissions were dominated by emissions from coal-fired power plants that were located to the northwest of the sampling site. These facilities represent the largest point emission sources of SO{sub 2}, and probably ultrafine ({lt}0.1 {mu}m) or submicron particles, in Rochester. Regionally transported material was characterized by accumulation mode particles. Air parcel back-trajectories showed transport of air masses from the industrial midwest.

Ogulei, D.; Hopke, P.K.; Chalupa, D.C.; Utell, M.J. [Clarkson University, Potsdam, NY (United States)

2007-02-15

38

Flow Velocity Computation, from Temperature and Number Density Measurements using Spontaneous Raman Scattering, for Supersonic Chemically Reacting Flows.  

NASA Astrophysics Data System (ADS)

The closure problem in chemically reacting turbulent flows would be solved when velocity, temperature and number density (transport variables) are known. The transport variables provide input to momentum, heat and mass transport equations leading to analysis of turbulence-chemistry interaction, providing a pathway to improve combustion efficiency. There are no measurement techniques to determine all three transport variables simultaneously. This paper shows the formulation to compute flow velocity from temperature and number density measurements, made from spontaneous Raman scattering, using kinetic theory of dilute gases coupled with Maxwell-Boltzmann velocity distribution. Temperature and number density measurements are made in a mach 1.5 supersonic air flow with subsonic hydrogen co-flow. Maxwell-Boltzmann distribution can be used to compute the average molecular velocity of each species, which in turn is used to compute the mass-averaged velocity or flow velocity. This formulation was validated by Raman measurements in a laminar adiabatic burner where the computed flow velocities were in good agreement with hot-wire velocity measurements.

Satish Jeyashekar, Nigil; Seiner, John

2006-11-01

39

Creation, Transport and Measurement of Bright Relativistic Electron Beams  

Microsoft Academic Search

This thesis deals with three topics relevant to linac-driven free electron lasers: the creation, transport and measurement of bright relativistic electron beams. Thermionic microwave electron guns produce bright electron beams that are well suited to drive free electron lasers, FELs. The rf fields in the gun cause some of the emitted electrons to reverse direction and strike the cathode. These

Chad Bennett McKee

1994-01-01

40

Temperature and number density measurements using Raman scattering in turbulent-supersonic-combusting flows  

NASA Astrophysics Data System (ADS)

Scramjet engines propelled at hypersonic velocities have the potential to replace existing rocket launchers. Commercializing the vehicle is an arduous task, owing to issues relating to low combustion efficiency. The performance, thrust, and speed of the engine can be improved by optimizing: turbulence-chemistry interaction to provide mixing conditions favorable for the chemistry, pressure buildup, and re-circulation of hydrogen throughout the engine. The performance of the engine can be measured, flow and chemical dynamics can be evaluated when all three variables in the transport equations are known. The variables are instantaneous flow velocity, static temperature (refers to the macroscopic temperature and not the molecular species temperature), and total number density at a point in the flow. The motive is to build a non-intrusive tool to measure thermodynamic quantities (static temperature and total number density). This can be integrated with a velocity measurement tool, in the future, to obtain all three variables simultaneously and instantaneously. The dissertation describes in detail the motivation for the proposed work, with introduction to the formalism involved, with a concise literature review, followed by mathematical perspective to obtain the working equations for temperature and number density. The design of the adiabatic burner and the experimental setup used for calibration is discussed with the uncertainty involved in measurements. The measurements are made for a certain set of flow conditions in the laminar burner by Raman scattering and is validated by comparing it to the theoretical/adiabatic flame temperature and mole fraction plots, in lean and rich regime. This technique is applied to turbulent, supersonic, hydrogen-air flame of an afterburning rocket nozzle. The statistics of temperature and total number density versus the corresponding values at adiabatic conditions gives the departure from thermal and chemical equilibrium. The extent of mixing and combustion can be concluded from such statistics. The future work will involve experimental modifications to make line and planar measurements in combusting jets.

Jeyashekar, Nigil Satish

41

Measurement of Water Transport from Saturated Pumice Aggregates to Hardening Cement Paste  

E-print Network

Measurement of Water Transport from Saturated Pumice Aggregates to Hardening Cement Paste by Pietro-ray absorption showed that considerable transport of water from saturated lightweight aggregates (pumice

Bentz, Dale P.

42

Investigation of Transonic Reynolds Number Scaling on a Twin-Engine Transport  

NASA Technical Reports Server (NTRS)

This paper discusses Reynolds number scaling for aerodynamic parameters including force and wing pressure measurements. A full-span model of the Boeing 777 configuration was tested at transonic conditions in the National Transonic Facility (NTF) at Reynolds numbers (based on mean aerodynamic chord) from 3.0 to 40.0 million. Data was obtained for a tail-off configuration both with and without wing vortex generators and flap support fairings. The effects of aeroelastics were separated from Reynolds number effects by varying total pressure and temperature independently. Data from the NTF at flight Reynolds number are compared with flight data to establish the wind tunnel/flight correlation. The importance of high Reynolds number testing and the need for developing a process for transonic Reynolds number scaling is discussed. This paper also identifies issues that need to be worked for Boeing Commercial to continue to conduct future high Reynolds number testing in the NTF.

Curtin, M. M.; Bogue, D. R.; Om, D.; Rivers, S. M. B.; Pendergraft, O. C., Jr.; Wahls, R. A.

2002-01-01

43

Status of local transport measurements and analysis in toroidal devices  

SciTech Connect

This paper reviews the status of methods used to analyze local transport of particles, energy, and angular momentum in plasmas contained in toroidal fusion devices. The standard technique at present is based on determination of particle, energy, and momentum fluxes through analysis based on measured profiles of density, temperature and angular rotation speed and on calculation of all sources of particles, energy, and momentum. Recent experiments have also been done using perturbations of local density, temperature, or angular rotation speed caused by modulating the input sources. The local transport information is then extracted from the time history of the perturbations. These two techniques are contrasted and the strengths of each are discussed in this paper. Recommendations for further work needed to make progress in understanding transport are also given.

Burrell, K.H. (General Atomics, San Diego, CA 92138 (USA)); Gentle, K.W. (University of Texas, Austin, Texas 78712 (USA)); Luhmann, N.C. Jr. (University of California at Los Angeles, Los Angeles, CA 90024 (USA)); Marmar, E.S. (Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (USA)); Murakami, M. (Oak Ridge National Laboratory, Oak Ridge, TN 37837 (USA)); Schoenberg, K.F. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (USA)); Tang, W.M.; Zarnstorff, M.C. (Plasma Physics Laboratory, Princeton, New Jersey 08543 (USA))

1990-12-01

44

Neutron spectroscopy measurements of tritium beam transport at JET  

NASA Astrophysics Data System (ADS)

A detailed description of the 14 MeV neutron emission in plasmas heated by neutral beam injection has been carried out by coupling Monte Carlo calculations of the neutron emission spectrum with TRANSP modelling of the beam ion energy distributions. The model is used to study tritium beam injection experiments of the JET trace tritium campaign for internal transport barrier (ITB) and H-mode discharges. For ITB discharges, the measured neutron emission spectrum is well described by modelling using as input the beam ion distribution calculated with TRANSP. For H mode discharges the neutron spectrum can be reproduced only if high energy tritons are lost from the plasma, suggesting the possible role of low frequency tearing modes on the beam ions. The presented results are of relevance for tritium beam transport studies in trace tritium experiments and, more generally, for deuterium and tritium transport studies in high power experiments using neutron emission spectroscopy.

Nocente, M.; Albergante, M.; Eriksson, J.; Conroy, S.; Ericsson, G.; Farina, D.; Hellesen, C.; Källne, J.; Popovichev, S.; Tardocchi, M.; Gorini, G.; contributors, JET-EFDA

2014-10-01

45

A rain splash transport equation assimilating field and laboratory measurements  

USGS Publications Warehouse

Process-based models of hillslope evolution require transport equations relating sediment flux to its major controls. An equation for rain splash transport in the absence of overland flow was constructed by modifying an approach developed by Reeve (1982) and parameterizing it with measurements from single-drop laboratory experiments and simulated rainfall on a grassland in East Africa. The equation relates rain splash to hillslope gradient, the median raindrop diameter of a storm, and ground cover density; the effect of soil texture on detachability can be incorporated from other published results. The spatial and temporal applicability of such an equation for rain splash transport in the absence of overland flow on uncultivated hillslopes can be estimated from hydrological calculations. The predicted transport is lower than landscape-averaged geologic erosion rates from Kenya but is large enough to modify short, slowly eroding natural hillslopes as well as microtopographic interrill surfaces between which overland flow transports the mobilized sediment. Copyright 2010 by the American Geophysical Union. Copyright 2010 by the American Geophysical Union.

Dunne, T.; Malmon, D.V.; Mudd, S.M.

2010-01-01

46

Capacitance-Voltage Measurement of Transporting Function at Cell Membrane  

NASA Astrophysics Data System (ADS)

In this paper, we report the detection of transporting function at cell membrane using capacitance-voltage (CV) measurement. The detection principle of our devices is based on the field-effect of electrostatic interaction between charged species at cell membrane in solution and surface electrons in silicon crystal through the gate insulator of Si3N4/SiO2 thin double-layer. We designed an oocyte-based field-effect capacitor, on which a Xenopus laevis oocyte was fixed. The transporter of human organic anion transporting peptide C (hOATP-C) was expressed at oocyte membrane by induction of cRNA. The electrical phenomena such as ion or molecular charge flux at the interface between cell membrane and gate surface could be detected as the change of flat band voltage in CV characteristics. The flat band voltage shift decreased with incubation time after introduction of substrate into the oocyte-based field-effect capacitor. The electrical signal is due to the change of charge flux from the oocyte at the gate surface inspired by transporter-substrate binding. The platform based on the oocyte-based field-effect capacitor is suitable for a simple and non-invasive detection system in order to analyze function of transporters related to drug efficacy.

Sakata, Toshiya; Miyahara, Yuji

47

Improving sediment transport measurements in the Erlenbach stream using a moving basket system  

NASA Astrophysics Data System (ADS)

In the Erlenbach stream, a prealpine torrent in Switzerland, sediment transport has been monitored for more than 25 years. Sediment transporting flood events in the Erlenbach are typically of short duration with a rapid rise of discharge during summer thunderstorms, thus hampering on-site measurements. On average there are more than 20 bedload transport events per year. Near the confluence with the main valley river, there is a stream gauging station and a sediment retention basin with a capacity of about 2,000 m3. The basin is surveyed at regular intervals and after large flood events. In addition, sediment transport has been continuously monitored with a piezoelectric bedload impact sensor (PBIS) array since 1986. The sensor array is mounted flush with the surface of a check dam immediately upstream of the retention basin. The PBIS system was developed to continuously measure the intensity of bedload transport and its relation to stream discharge. To standardize the sensors, the piezoelectric crystals were replaced by geophones in 2000. The geophone measuring system has also been employed at a number of other streams. In 2008, the measuring system in the Erlenbach stream has been enhanced with an automatic system to obtain bedload samples. Movable, slot-type cubic metal baskets are mounted on a rail at the downstream wall of the large check dam above the retention basin. The metal baskets can be moved automatically and individually into the flow according to flow and bedload transport conditions (i.e. geophone recordings). The basket is stopped at the centerline of the approach flow channel of the overflow section to obtain a sediment sample during a limited time interval. The wire mesh of the basket has a spacing of 10 mm to sample all sediment particles coarser than this size (which is about the limiting grain size detected by the geophones). The weight increase due to the collected sediment is measured by weighing cells located in the basket supporting structure, and this information is used in combination with the geophone recordings to determine when to move a basket laterally away from the flow. The upgraded measuring system allows: (i) to obtain bedload samples over short sampling periods; (ii) to measure the grain size distribution of the transported material and its variation over time and with discharge; (iii) to obtain direct bedload measurements that can be used to improve the understanding of the geophone signal; and (iv) to improve the geophone calibration for the Erlenbach stream. We introduce the new measuring installations, discuss our experience from the first successful automatic sampling operations in summer 2009, and we present first results.

Rickenmann, Dieter; Turowski, Jens; Hegglin, Ramon; Fritschi, Bruno

2010-05-01

48

Moisture dependence of radon transport in concrete: measurements and modeling.  

PubMed

The moisture dependence of the radon-release rate of concrete was measured under well controlled conditions. It was found that the radon-release rate almost linearly increases up to moisture contents of 50 to 60%. At 70 to 80% a maximum was found and for higher moisture contents the radon-release rate decreases very steeply. It is demonstrated that this dependence can be successfully modeled on basis of the multi-phase radon-transport equation in which values for various input parameters (porosity, diffusion coefficient, emanation factor, etc.) were obtained from independent measurements. Furthermore, a concrete structure development model was used to predict at any moment in time the values of input parameters that depend on the evolution of the concrete microstructure. Information on the concrete manufacturing recipe and curing conditions (temperature, relative humidity) was used as input for the concrete structure model. The combined radon transport and concrete structure model supplied sufficient information to assess the influence of relative humidity on the radon source and barrier aspects of concrete. More specifically, the model has been applied to estimate the relative contributions to the radon exhalation rate of a 20-cm-thick concrete slab of radon produced in the concrete slab itself and due to diffusive transport through the slab of radon from soil gas. PMID:13678285

Cozmuta, I; van der Graaf, E R; de Meijer, R J

2003-10-01

49

Numbers  

NSDL National Science Digital Library

The purpose of this video tutorial is to review a couple ways in which we think about numbers. Thinking in terms of street numbers, money in bank accounts, and quantum particles (e.g. Bose-Einstein condensate) is contrasted with focusing on associating numbers with distinguishable manipulatives, as is more familiar in K-8 courses. This video concludes with a reminder that the symbol "infinity" is not, itself, a number.

2013-06-14

50

Measuring hot plasma transport coefficients with stripped cluster galaxies  

NASA Astrophysics Data System (ADS)

Cluster galaxies are gas-stripped during their motion through the cluster gas. Thermal conductivity and viscosity of the hot gas -or plasma- in and around these galaxies affect the stripping mechanisms, and in particular the multiphase nature of the tails of stripped gas and star formation in tails of the spirals. However, the effective transport coefficients are still ill-constrained. Current deep X-ray observations of stripped nearby cluster ellipticals show the details of the plasma flows around them. We aim at measuring the effective plasma transport coefficients by means of one-to-one comparisons to viscous hydro-simulations tailored to each galaxy. We report first evidence for a highly suppressed viscosity around Virgo and Fornax cluster ellipticals and discuss future observations.

Roediger, Elke

2014-08-01

51

Numbers  

NSDL National Science Digital Library

This engaging web site contains information and interactive applets related to various number systems: Egyptian, Babylonian, Chinese, Greek, Roman, Mayan, and Arabic. Users learn the history and structure of each system as well as how to count and write numbers. The site also allows users to explore finger systems, calculating machines, other number bases, and "interesting numbers." A series of pages on data and graphs includes information and activities on gathering, analyzing, graphing and sorting data. (Because the section on the Arabic number system is so extensive, it is cataloged separately as a related resource.)

Edkins, Jo

2006-01-01

52

Prediction uncertainty of plume characteristics derived from a small number of measuring points  

NASA Astrophysics Data System (ADS)

A small number of measuring points may inflict a bias on the characterisation of flow and transport based on field experiments in the unsaturated zone. Simulation of pure advective transport of a Gaussian plume through a setup of 30 regularly placed measuring points revealed regular temporal fluctuations about the real spatial moments. An irregular setup predicted both irregular fluctuations and larger discrepancies from the real value. From these considerations, a regular setup is recommended. Spatial moments were sensitive to the plume size relative to the distance between individual measuring points. To reduce prediction errors of the variance, the distance between the measuring points should be less than twice the standard deviation of the examined plume. The total size of the setup should cover several standard deviations of the plume to avoid mass being lost from the monitored area. Numerical simulations of a dispersing plume (comparing calculations based on 9000 nodes with 30 measuring points) revealed that vertical and horizontal centres of mass were predicted well at all degrees of heterogeneity, and the same was the case for horizontal variances. Vertical variances were more susceptible to prediction errors, but estimates were of the same order of magnitude as the real values. Résumé Lorsque l'on cherche à caractériser l'écoulement et le transport à partir d'expériences de terrain dans la zone saturée, il arrive qu'un petit nombre de points introduisent un biais. La simulation d'un transport purement advectif d'un panache gaussien au travers d'un ensemble de 30 points de mesures espacés régulièrement fait apparaître des variations temporelles régulières autour des moments spatiaux réels. Un ensemble irrégulier conduit à prédire à la fois des variations irrégulières et de plus grandes divergences par rapport à la valeur réelle. A partir de ces constations, un ensemble régulier est recommandé. Les moments spatiaux sont apparus sensibles à la dimension du panache en fonction de la distance entre les différents points de mesure. Afin de réduire les erreurs de prédiction de la variance, la distance entre les points de mesure doit être inférieure au double de l'écart-type du panache examiné. La dimension totale de l'ensemble doit couvrir une étendue de plusieurs écarts-types du panache pour éviter qu'une partie de la matière échappe à la zone surveillée. Des simulations numériques du panache en dispersion (les calculs de comparaison sont basés sur 9000 nœuds avec 30 points de mesure) montrent que le centre vertical et le centre horizontal de la matière dispersée ont été bien prédits à tous les degrés d'hétérogénéité, de même que pour les variances horizontales. Les variances verticales ont été plus sensibles aux erreurs de prédiction, mais les estimations étaient du même ordre de grandeur que les valeurs réelles. Resumen Un número pequeño de puntos de medida puede producir un sesgo en la caracterización en campo del flujo y transporte de solutos en la zona no saturada. La simulación de transporte advectivo (no difusivo) de un penacho Gaussiano a travs de un conjunto de 30 puntos de medida regularmente distribuidos revelan fluctuaciones temporales regulares de los momentos espaciales del penacho. Una distribución irregular de puntos de medida predijo a su vez fluctuaciones irregulares, más alejadas de la realidad, por lo que se recomienda el uso de esquemas de muestreo regulares. Los momentos espaciales fueron sensibles a la relación entre tamaño del penacho y distancia entre puntos de medida. Para reducir los errores en la predicción de la varianza, la distancia entre puntos de observación debe ser menor que dos veces la desviación estándar del penacho. El tamaño del área muestreada debe cubrir varias desviaciones estándar del penacho para evitar perder parte de la masa. Las simulaciones numricas en un penacho dispersivo, comparando los cálculos basados en 9000 nudos con las 30 medidas, mostraron que las posiciones de los centros de masa y

French, H. K.; van der Zee, S. E. A. T. M.; Leijnse, A.

53

Electron Temperature Measurements and Energy Transport in SSPX  

NASA Astrophysics Data System (ADS)

Time-resolved measurements (<100 ?s) have been made with a multi-pulse Thomson scattering diagnostic in the SSPX spheromak experiment, to obtain radial electron density and temperature profile during plasma formation and sustainment. In most discharges three regimes are observed with respect to Te and ne evolution. Initially there is a cold (<100 eV) formation phase, followed by a hollow Te profile with maximum temperatures 100-200 eV, and a final heat-up and cool-down phase where we obtain the highest plasma temperatures (350+ eV). The transition from hollow to peaked Te is quite sharp (˜50 ?s) and the recent upgrade to double-pulse Thomson scattering (˜40 ?s between pulses) facilitates capturing this transition. We also present simulations using the CORSICA code where the equilibrium is kept fixed and the discharge is evolved to observe the change in temperature profiles for different transport coefficients. In addition, electron transport and heating will be correlated with measured MHD mode activity. Temperature and density measurements during multi-pulse coaxial gun-current operation will also be presented. * Work performed under the auspices of the US DOE by University of California Lawrence Livermore National Laboratory under contract W--7405--ENG--48.

Hudson, B. F.; Casper, T. A.; Hooper, E. B.; Jayakumar, R. J.; Lodestro, L. L.; McLean, H. S.; Moller, J. M.; Romero-Talamas, C. A.; Wood, R. D.

2007-11-01

54

Dynamics of Mass Transport and Magnetic Fields in Low-Wire-Number-Array Z Pinches  

SciTech Connect

The dynamics of mass transport were observed in a wire array implosion with multiframe laser probing. Plasma bubbles arise at breaks in the wires. Interferometry shows that the leading edge of the bubbles brings material to the axis of the array. The speed of this material was measured to be {>=}3x10{sup 7} cm/s during the wire array implosion. A shock was observed during the collision of the bubbles with the precursor. The Faraday effect indicates current flowing in breaks on the wires. The current switches from the imploding mass to the on-axis plasma column at the beginning of the x-ray pulse.

Ivanov, V. V.; Sotnikov, V. I.; Cowan, T. E.; Laca, P. J.; Astanovitskiy, A. L.; Haboub, A. [University of Nevada, Reno, 5625 Fox Ave, Reno, Nevada 89506 (United States); Sarkisov, G. S.; Jones, B.; Coverdale, C. A.; Deeney, C. [Sandia National Laboratories, Albuquerque, New Mexico 87110 (United States); Bland, S. N. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)

2006-09-22

55

Regulation of the GLUT1 glucose transporter in cultured myocytes: total number and subcellular distribution as determined by photoaffinity labelling.  

PubMed Central

We have used the impermeant photoaffinity label 2-N-4-(1-azi-2,2,2-trifluoroethyl)benzoyl-[2-3H] 1,3-bis-(D-mannos-4-yloxy)-2-propylamine (ATB-[2-3H]BMPA) to identify and quantify the glucose transporters on the surface of BC3H-1 cells, a continuously cultured skeletal-muscle cell line lacking the MyoD transcription factor required for cell fusion. ATB-[2-3H]BMPA was used in combination with immunoprecipitation of the GLUT1 glucose transporter, the only isoform expressed in these cells. The total cellular GLUT1 content was also determined by photolabelling and immunoprecipitation after cell permeabilization with digitonin (0.025%). In glucose-starved cells, 85% of the glucose transporters were present at the cell surface in the basal state, with little change in response to insulin (200 nM), correlating with lack of additional 2-deoxyglucose uptake in response to insulin. Feeding the cells with glucose (25 mM) for 24 h resulted in an 80% decrease in the total GLUT1 content relative to starved cells, of which only 25% were present on the cell surface. This was associated with an 85% decrease in 2-deoxyglucose uptake. In addition, acute stimulation of the fed cells with insulin or phorbol 12-myristate 13-acetate (PMA) led to an increase in GLUT1 at the cell surface, and, in correspondence, an increase in 2-deoxyglucose uptake by approx. 2- and 4-fold respectively. We conclude that exofacial photoaffinity labelling of glucose transporters with ATB-[2-3H]BMPA in the presence and absence of digitonin, followed by specific immunoprecipitation, provides an accurate measure of total and cell-surface glucose transporters in differentiated BC3H-1 muscle cells. This technique demonstrates that glucose pre-feeding (1) decreases the total number of GLUT1 and (2) redistributes the majority of the remaining transporters to an intracellular site, where they can now be translocated to the cell surface in response to insulin and PMA. PMID:8037688

el-Kebbi, I M; Roser, S; Pollet, R J; Cushman, S W; Wilson, C M

1994-01-01

56

Field measurements of tracer gas transport by barometric pumping  

SciTech Connect

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

Lagus, P.L. [Lagus Applied Technology, San Diego, CA (United States); McKinnis, W.B. [Lawrence Livermore National Lab., Mercury, NV (United States); Hearst, J.R.; Burkhard, N.R.; Smith, C.F. [Lawrence Livermore National Lab., CA (United States)

1994-07-28

57

Phase Measurement of Galvanneal Task JPL Task Order Number: RF-152 Amendment Number: 543  

SciTech Connect

The objective of this task was to demonstrate an x-ray fluorescence (XRF) technique which would measure the phase composition of galvanneal coatings of sheet steel rapidly and non-destructively with an accuracy of 0.5%. This data acquisition and analysis method would be implemented as an on-line process control input. The AISI sample matrix evaluated for this study is shown in Appendix I. The Jet Propulsion Laboratory (JPL) and Data Measurement Corporation (DMC) measured iron and zinc XRF responses from these samples. In addition, JPL performed metallograph, x-ray diffraction (XRD), and transmission electron microscopy (TEM) to characterize the samples' galvanneal phase morphology. This data was correlated with the XRF experimental results and then compared to phase composition models, which were generated using a Fundamental Parameters Method (FPM) approach.

Lynn Lowry; Beverly Tai

1995-03-01

58

Direct measurements of transport properties are essential for site characterization  

SciTech Connect

Direct measurements of transport parameters on subsurface sediments using, the UFA method provided detailed hydrostratigraphic mapping, and subsurface flux distributions at a mixed-waste disposal site at Hanford. Seven hundred unsaturated conductivity measurements on fifty samples were obtained in only six months total of UFA run time. These data are used to provide realistic information to conceptual models, predictive models and restoration strategies. The UFA instrument consists of an ultracentrifuge with a constant, ultralow flow pump that provides fluid to the sample surface through a rotating seal assembly and microdispersal system. Effluent from the sample is collected in a transparent, volumetrically-calibrated chamber at the bottom of the sample assembly. Using a strobe light, an observer can check the chamber while the sample is being centrifuged. Materials can be run in the UFA as recomposited samples or in situ samples can be subcored directly into the sample UFA chamber.

Wright, J. [Pacific Northwest Lab., Richland, WA (United States); Conca, J.L. [Washington State Univ. Tri-Cities, Richland, WA (United States). Environmental Sciences

1994-08-01

59

Tunneling and transport measurements of quench-condensed Bi films  

NASA Astrophysics Data System (ADS)

We report tunneling and transport measurements of quench-condensed superconducting Bi films. Samples were deposited directly onto both clean glass substrates and over oxidized Al ground planes and tunnel electrodes without the use of a Ge or Sb underlayer. Values for the superconducting energy gap ? were derived from BCS fits to the tunneling curves, and the transition temperature TC values were obtained from fits to the Aslamazov-Larkin fluctuation theory. The ratio raise0.7ex2? mathord/ hantom 2? kB TC .kern-?lldelimiterspacelower0.7exkB TC was found to be significantly different than expected for samples that were deposited onto clean glass for the transport measurement. Better comparisons resulted for samples over the same Al/Al_2O3 preparation as the tunnel electrode. However, these latter results are complicated by the presence of a parallel conduction path. The results will be discussed within the context of morphological differences arising from the different substrate preparations.

Barber, Richard

2004-03-01

60

Lessons learned from the jellyfish: Fluid transport at intermediate Reynolds numbers  

NASA Astrophysics Data System (ADS)

Biologically inspired hydrodynamic propulsion and maneuvering strategies promise the advancement of medical implants and novel robotic tools. We have chosen juvenile jellyfish as a model system for investigating fluid dynamics and morphological properties underlying fluid transport by an elastic system at intermediate Reynolds numbers. Recently we have described how natural variations in viscous forces are balanced by changes in jellyfish body shape (phenotypic plasticity), to the effect of facilitating efficient body-fluid interaction. Complementing these studies in our live model organisms, we are also engaged in engineering a synthetic jellyfish, that is, a rhythmically actuated elastomer capable of generating efficient feeding and propulsion currents. The main challenges here are (1) to derive a body shape and deformation suitable for effective fluid transport under physiological fluid conditions, (2) to understand the mechanical properties of actuator and elastomer to derive a design capable of the desired deformation, (3) to establish adequate 3D kinematics of power and recovery stroke, and (4) to evaluate the performance of the design.

Nawroth, Janna; Dabiri, John

2011-11-01

61

Learning from jellyfish: Fluid transport in muscular pumps at intermediate Reynolds numbers  

NASA Astrophysics Data System (ADS)

Biologically inspired hydrodynamic propulsion and maneuvering strategies promise the advancement of medical implants and minimally invasive clinical tools. We have chosen juvenile jellyfish as a model system for investigating fluid dynamics and morphological properties underlying fluid transport by a muscular pump at intermediate Reynolds numbers. Recently we have described how natural variations in viscous forces are balanced by changes in jellyfish body shape (phenotypic plasticity), to the effect of facilitating efficient body-fluid interaction. Complementing these studies in our live model organisms, we are also engaged in engineering an artificial jellyfish, that is, a jellyfish-inspired construct of a flexible plastic sheet actuated by a monolayer of rat cardiomyocytes. The main challenges here are (1) to derive a body shape and deformation suitable for effective fluid transport under physiological conditions, (2) to understand the mechanical properties of the muscular film and derive a design capable of the desired deformation, (3) to master the proper alignment and timely contraction of the muscle component needed to achieve the desired deformation, and (4) to evaluate the performance of the design.

Nawroth, Janna; Dabiri, John

2010-11-01

62

Bacterial Abundance Measure bacterial numbers and mass per unit volume.  

E-print Network

that contains medium for the culturing of fecal coliform bacteria (contains eosin-methylene blue dye) · Incubate ml-1 B U G CO2 B Time Conc. R #12;How is bacterial concentration measured? Laboratory cultures to directly count bacteria. Problem: Bacteria in natural environments are very small and difficult to see

Vallino, Joseph J.

63

The Case for Multiple Measures. Info Brief. Number 52  

ERIC Educational Resources Information Center

What is the best use for tests? Testing should provide insight and information to educators and students. The primary purpose of testing is to inform teaching and learning. Yet, for too many schools, testing has been perverted to accommodate only measurement. Lesson plans are built around helping students pass the tests. In many instances, schools…

Fuller, Dan; Fitzgerald, Kevin; Lee, Ji Sun

2008-01-01

64

Similarity Measure and Fuzzy Entropy of Fuzzy Number Intuitionistic Fuzzy Sets  

Microsoft Academic Search

Based on the similarity measure of trigonometric fuzzy numbers, similarity measures for measuring the degree of similarity\\u000a between elements and between some fuzzy number intuitionistic fuzzy sets are defined by the one-to-one correspondence relation\\u000a between the distance and similarity measure. At the same time, the fuzzy entropy for fuzzy number intuitionistic fuzzy sets\\u000a is proposed. After that, their properties are

Juan Li; Qi Niu; Cheng-yi Zhang

65

Measurements in a High Reynolds Number Deep-Channel Viscometer  

NASA Astrophysics Data System (ADS)

Experiments were conducted using a deep-channel viscometer, which consists of an annular region where the liquid is bounded by stationary inner and outer cylinders, a rotating floor, and a free surface. The deep-channel was originally devised for the low-speed, linear regime to measure the surface shear viscosity (?^s) at a given uniform surfactant surface concentration. This apparatus, when driven faster into the nonlinear regime, produces a strong secondary flow that results in a surface velocity with a significant radial component and a nonuniform distribution of surfactant at the air/water interface. A precision viscometer was constructed of glass for optical access. The application of a new boundary-fitted, digital particle image velocimetry (DPIV) technique for measurement of the surface velocity, and second-harmonic generation (SHG) for surfactant concentration will be discussed. These measurements can produce a direct determination of surface dilatational viscosity (?^s), as well as ?^s. The present experiments were conducted at Re based on radius of up to 10^4, well beyond the Stokes flow limit of order 10^2 for this flow. Additionally, a new approach for modeling ?^s based on the functional form of ?^s will also be discussed. This method does not require DPIV or SHG, but instead relies on Navier-Stokes computations in conjunction with visualization of a seeding particle on the interface.

Hirsa, A.; Korenowski, G. M.; Ringuette, M. J.; Joshi, A. A.; Lopez, J. M.

1998-11-01

66

Creation, Transport and Measurement of Bright Relativistic Electron Beams.  

NASA Astrophysics Data System (ADS)

This thesis deals with three topics relevant to linac-driven free electron lasers: the creation, transport and measurement of bright relativistic electron beams. Thermionic microwave electron guns produce bright electron beams that are well suited to drive free electron lasers, FELs. The rf fields in the gun cause some of the emitted electrons to reverse direction and strike the cathode. These back-bombarding electrons heat the cathode limiting both the pulse length and time averaged current. The cathode heating is reduced if a transverse magnetic field is applied across the gun cavity to deflect back-bombarding electrons. We improve the thermionic microwave electron gun by redesigning the deflection magnet to minimize the back-heating power. Computer simulations show that transverse magnetic fields with rapid axial falloffs reduce the back-heating power more than fields that are axially constant. Experiments verify these simulations. The deflection magnet presently installed on the Mark III gun has a slow axial falloff and reduces the back-heating power by 31%. Using the simulation results we design a new deflection magnet having a rapid axial falloff. This magnet has been installed on the NCCU gun and reduces the back-heating power by 63%. Improper transport of the electron beam through the beam line degrades the quality of the electron beam and lowers the performance of the FEL. We propose to improve the beam line commissioning and control procedures on linac -driven FELs by experimentally measuring the transfer matrix of each beam line section. The transfer matrix of a given section is measured by dithering the electron beam, measuring the beam vector before and after the section and inverting the subsequent data matrix. We minimize the beam line errors by minimizing the deviation between the experimentally measured transfer matrix and the design transfer matrix of each beam line section. While not experimentally verified, computer simulations show that this technique can be very effective in bringing the experimental beam line close to its design specifications. The performance of an FEL depends on various characteristics of the electron beam used to drive it. The gain of the laser especially depends on the transverse phase space distribution of the electrons. Previously it has not been possible to measure the details of the transverse phase space distribution of high-energy electron beams with the precision required to predict FEL performance. Standard techniques for measuring the transverse phase space of relativistic electron beams treat the phase space distributions as ellipses and only measure the sigma matrices that define the ellipses. These techniques give no information about the detailed structure of the phase space distributions. We have developed a new technique to measure transverse phase space that combines quadrupole-scanning techniques with tomographic image reconstruction to measure the actual phase space distributions while making no a priori assumptions about the distributions. Using this process, we are able to reconstruct phase space distributions that are not elliptical. Both computer simulations and experiments verify that phase space tomography makes the detailed measurement of the phase space distributions possible at high energies. Detailed reconstructions of the phase space distribution of a 44 MeV electron beam from the Mark III FEL are presented.

McKee, Chad Bennett

67

Lidar measurements of Saharan dust transportation over Sofia  

NASA Astrophysics Data System (ADS)

Within the framework of the project "EARLINET-ASOS (European Aerosol Research Lidar Network - Advanced Sustainable Observation System)" Contract No 025991 of European Commission's Framework Program 6 (EC FP6) (http://www.earlinet.org), transportation of Saharan dust over Europe has been observed in the sky over Sofia, during the last week of May, 2008. This phenomena, predicted by the Atmospheric Modeling and Weather Forecasting Group of National Technical University of Athens (NTUA) (http://forecast.uoa.gr/) and the Forecast system of Barcelona Supercomputing Center (BSC) (http://www.bsc.es/projects/ earthscience/DREAM), was interesting with its relatively long-time existence and large scale of propagation over the continent. In this work, we present the results and some comments of the measurements of the atmospheric backscatter coefficient made in Sofia, using aerosol lidar with CuBrvapor laser.

Grigorov, I. V.; Kolarov, G. V.; Stoyanov, D. V.

2008-12-01

68

Measurement of Instantaneous Velocity Vectors of Organelle Transport: Mitochondrial Transport and Bioenergetics in Hippocampal Neurons  

PubMed Central

Impaired transport of mitochondria, in dendrites and axons of neurons, and bioenergetic deficit are increasingly recognized to be of pathological importance in neurodegenerative diseases. To study the relationship between transport and bioenergetics, we have developed what to our knowledge is a novel technique to quantify organelle velocity in cultured cells. The aim was to combine measurement of motion and bioenergetic parameters while minimizing photodynamic oxidative artifacts evoked by fluorescence excitation. Velocity determination from sequential fluorescence images is not trivial, and here we describe an application of “optical flow”, the flow of gray values in grayscale images, to this problem. Based on the principles of photon shot noise occurring in low light level fluorescence microscopy, we describe and validate here an optical flow-based, robust method to measure velocity vectors for organelles expressing fluorescent proteins. This method features instantaneous velocity determination from a pair of images by detecting motion of edges, with no assumptions about the separation or shapes of the objects in the image. Optical flow was used in combination with single mitochondrion assay of mitochondrial thiol redox status by mitochondrially targeted redox-sensitive green fluorescent protein and measurement of mitochondrial membrane potential by tetramethylrhodamine methyl ester. Mitochondrial populations of resting cultured hippocampal neurons were analyzed. It was found that mitochondria with more oxidized thiol redox status have lower membrane potentials and are smaller in size. These mitochondria are more motile than the average; however, mitochondrial motility is only slightly dependent on the observed bioenergetic parameters and is correlated the best to the size of the mitochondria. PMID:18757564

Gerencser, Akos A.; Nicholls, David G.

2008-01-01

69

Direct Measurements of Eddy Transport and Thermal Dispersion in a High Porosity Matrix  

NASA Technical Reports Server (NTRS)

Thermal losses from the hot end to the cold end of a Stirling cycle regenerator due to thermal dispersion through the regenerator matrix may significantly degrade the performance of the machine. Because of poor access to the void spaces within the porous medium, no direct measurements of thermal dispersion have been made and dispersion models have been derived indirectly. This is done by measuring the overall thermal performance of the regenerator and subtracting off the energy transfer caused by molecular conduction and advected enthalpy flows computed from volume-averaged fluid velocity and temperature. In the current program, a large-scale porous matrix consisting of stacked wire screens with a porosity of 90% is installed in a flow rig which is operated in a Reynolds number range that represents Stirling engine regenerator flow. Experiments are conducted to measure turbulent transport of momentum at the exit phase using hot-wires. The relationship of such turbulent transport terms to the thermal dispersion term in the volumetric-averaged energy equation for the regenerator matrix is developed and the measurements are used to determine cross-stream thermal dispersion. A dispersion model based upon the measurements is proposed and compared with models documented in the literature.

Niu, Yi; Simon, David; Gedeon, David

2004-01-01

70

Measurement of implanted helium particle transport by a flowing liquid lithium film  

NASA Astrophysics Data System (ADS)

Due to its low atomic number, low sputtering yield, high sputtered ion fraction and excellent thermal properties, liquid lithium has been proposed as a potential candidate for advanced plasma-facing components (PFC). Using a liquid material opens the possibility of a continuously flowing, self-regenerating plasma-facing surface with a small residence time. This would allow such component to handle very high heat loads that are expected. There are, however, multiple unanswered questions regarding how such a liquid PFC would interact with the plasma in the reactor. The issue of particle control is critical, and it can be a factor to determine the feasibility of these advanced concepts. Hydrogen and helium are important in this regard: hydrogen transport by a flowing PFC impacts the reactor fuel recycling regime and tritium inventory; helium transport can help quantify ash removal by the flowing PFC. The flowing liquid-metal retention experiment (FLIRE) was built at the University of Illinois to answer some of the questions regarding particle transport by flowing liquid films exposed to plasmas. Experimental results regarding helium transport by a flowing lithium film after irradiation with an energetic He ion beam are presented in this work. Retained fraction values up to 2% were measured for the experimental conditions, and the retention was found to increase linearly with implanted ion energy. A pure diffusion model was used to describe the helium transport by the Li film, and it was found that such model predicts a diffusion coefficient of (2.8 ± 0.6) × 10 -11 m 2/s, based on the experimental retention measurements. Preliminary evidence of long-term trapping of helium will also be presented.

Nieto, M.; Ruzic, D. N.; Olczak, W.; Stubbers, R.

2006-04-01

71

Method measuring oxygen tension and transport within subcutaneous devices.  

PubMed

Cellular therapies hold promise to replace the implantation of whole organs in the treatment of disease. For most cell types, in vivo viability depends on oxygen delivery to avoid the toxic effects of hypoxia. A promising approach is the in situ vascularization of implantable devices which can mediate hypoxia and improve both the lifetime and utility of implanted cells and tissues. Although mathematical models and bulk measurements of oxygenation in surrounding tissue have been used to estimate oxygenation within devices, such estimates are insufficient in determining if supplied oxygen is sufficient for the entire thickness of the implanted cells and tissues. We have developed a technique in which oxygen-sensitive microparticles (OSMs) are incorporated into the volume of subcutaneously implantable devices. Oxygen partial pressure within these devices can be measured directly in vivo by an optical probe placed on the skin surface. As validation, OSMs have been incorporated into alginate beads, commonly used as immunoisolation devices to encapsulate pancreatic islet cells. Alginate beads were implanted into the subcutaneous space of Sprague–Dawley rats. Oxygen transport through beads was characterized from dynamic OSM signals in response to changes in inhaled oxygen. Changes in oxygen dynamics over days demonstrate the utility of our technology. PMID:25162910

Weidling, John; Sameni, Sara; Lakey, Jonathan R T; Botvinick, Elliot

2014-08-01

72

Grant Title: METHODOLOGY, MEASUREMENT, AND STATISTICS Funding Opportunity Number: NSF 12-510.  

E-print Network

Grant Title: METHODOLOGY, MEASUREMENT, AND STATISTICS Funding Opportunity Number: NSF 12; Division of Social and Economic Sciences. Area of Research: Proposals that are methodologically innovative: The Methodology, Measurement, and Statistics (MMS) Program is an interdisciplinary program in the Social

Farritor, Shane

73

Magnetorotational Turbulence Transports Angular Momentum in Stratified Disks with Low Magnetic Prandtl Number but Magnetic Reynolds Number above a Critical Value  

NASA Astrophysics Data System (ADS)

The magnetorotational instability (MRI) may dominate outward transport of angular momentum in accretion disks, allowing material to fall onto the central object. Previous work has established that the MRI can drive a mean-field dynamo, possibly leading to a self-sustaining accretion system. Recently, however, simulations of the scaling of the angular momentum transport parameter ?SS with the magnetic Prandtl number Pm have cast doubt on the ability of the MRI to transport astrophysically relevant amounts of angular momentum in real disk systems. Here, we use simulations including explicit physical viscosity and resistivity to show that when vertical stratification is included, mean-field dynamo action operates, driving the system to a configuration in which the magnetic field is not fully helical. This relaxes the constraints on the generated field provided by magnetic helicity conservation, allowing the generation of a mean field on timescales independent of the resistivity. Our models demonstrate the existence of a critical magnetic Reynolds number Rmcrit, below which transport becomes strongly Pm-dependent and chaotic, but above which the transport is steady and Pm-independent. Prior simulations showing Pm dependence had Rm < Rmcrit. We conjecture that this steady regime is possible because the mean-field dynamo is not helicity-limited and thus does not depend on the details of the helicity ejection process. Scaling to realistic astrophysical parameters suggests that disks around both protostars and stellar mass black holes have Rm Gt Rmcrit. Thus, we suggest that the strong Pm dependence seen in recent simulations does not occur in real systems.

Oishi, Jeffrey S.; Mac Low, Mordecai-Mark

2011-10-01

74

Magnetorotational Turbulence Transports Angular Momentum in Stratified Disks with Low Magnetic Prandtl Number but Magnetic Reynolds Number above a Critical Value  

SciTech Connect

The magnetorotational instability (MRI) may dominate outward transport of angular momentum in accretion disks, allowing material to fall onto the central object. Previous work has established that the MRI can drive a mean-field dynamo, possibly leading to a self-sustaining accretion system. Recently, however, simulations of the scaling of the angular momentum transport parameter {alpha}{sub SS} with the magnetic Prandtl number Pm have cast doubt on the ability of the MRI to transport astrophysically relevant amounts of angular momentum in real disk systems. Here, we use simulations including explicit physical viscosity and resistivity to show that when vertical stratification is included, mean field dynamo action operates, driving the system to a configuration in which the magnetic field is not fully helical. This relaxes the constraints on the generated field provided by magnetic helicity conservation, allowing the generation of a mean field on timescales independent of the resistivity. Our models demonstrate the existence of a critical magnetic Reynolds number Rm{sub crit}, below which transport becomes strongly Pm-dependent and chaotic, but above which the transport is steady and Pm-independent. Prior simulations showing Pm-dependence had Rm < Rm{sub crit}. We conjecture that this steady regime is possible because the mean field dynamo is not helicity-limited and thus does not depend on the details of the helicity ejection process. Scaling to realistic astrophysical parameters suggests that disks around both protostars and stellar mass black holes have Rm >> Rm{sub crit}. Thus, we suggest that the strong Pm dependence seen in recent simulations does not occur in real systems.

Oishi, Jeffrey S.; /KIPAC, Menlo Park; Low, Mordecai-Mark Mac; /Amer. Museum Natural Hist.

2012-02-14

75

Measurement of the copy number of the master quorum-sensing regulator of a bacterial cell  

E-print Network

Measurement of the copy number of the master quorum-sensing regulator of a bacterial cell Shu information on parameters such as the copy number of particular quorum-sensing proteins should contribute strongly to understanding how the quorum-sensing network functions. Here we show that the copy number

Ong, N. P.

76

Improving sediment transport measurements in the Erlenbach stream using a moving basket system  

Microsoft Academic Search

In the Erlenbach stream, a prealpine torrent in Switzerland, sediment transport has been monitored for more than 25 years. Sediment transporting flood events in the Erlenbach are typically of short duration with a rapid rise of discharge during summer thunderstorms, thus hampering on-site measurements. On average there are more than 20 bedload transport events per year. Near the confluence with

Dieter Rickenmann; Jens Turowski; Ramon Hegglin; Bruno Fritschi

2010-01-01

77

A transportable hemispherical illumination system for making reflectance factor measurements  

NASA Technical Reports Server (NTRS)

An artificial source of stable, hemispherical illumination has been developed to facilitate the collection of reflectance factor measurements of targets of interest in a laboratory environment. The light source consists of a 76 cm (30 in.) aluminum hemisphere which has been coated internally with barium sulfate paint. Illumination is provided by two banks of lamps, each consisting of eight 62-W quartz halogen bulbs which have tungsten filaments. An internal baffle precludes the viewing of any direct beam of light. A simple metal structure has been developed to hold the hemisphere and all peripheral equipment, such as spectrometers, radiometers, and cameras, in place during data collection. The entire setup can be easily disassembled and packed in airline approved shipping cases to facilitate transportation to remote laboratory facilities. This illumination system has been used during the past three years to collect spectral reflectance factor data of tree branch samples and seedlings in support of an on-going study to investigate the effect of acidic deposition on forest vegetation.

Williams, Darrel L.; Wood, Frank M., Jr.

1987-01-01

78

Transport and STM measurements of HCI modified materials  

NASA Astrophysics Data System (ADS)

While more than a decade of work has provided glimpses into the physics of highly charged ion (HCI) neutralization on surfaces, two prominent objectives remain unfulfilled: (1) a unified, quantitative model for separating the kinetic energy response of a wide range of materials classes from the effects of HCIs' potential energy effects and (2) insertion of HCI technology(s) as a cost-effective processing tool in a high-volume market sector. The National Institute of Standards and Technology (NIST) electron beam ion trap (EBIT) facility has recently incorporated tools for preparing clean, atomically flat surfaces of single crystals from gold to tungsten to silicon and for depositing and patterning thin films that range from high resistivity oxides to transition metals like cobalt and nickel. Current activities are focused on utilizing this unique capability to simultaneously address both of the objectives above by employing technologically important magnetic multi-layer systems to perform transport measurements that provide new insight into the fundamental processes that occur during HCI-surface neutralization. Specifically, we are producing Magnetic Tunnel Junctions (MTJs) critical to both magnetic devices and incorporating HCIs in the processing recipe to adjust critical electronic properties that are currently inhibiting their advancement. In return, the electrical response of the tunnel junction to the HCI processing provides a novel approach to performing ensemble measurements of HCI-surface interactions. By varying the construction of the tunnel junction, critical tests of the role of electron density, densities of states and electronic structure in the HCI-surface charge exchange can be performed.

Pomeroy, J. M.; Grube, H.; Perrella, A. C.; Sosolik, C. E.; Gillaspy, J. D.

2007-03-01

79

Measurements and modeling of deposited particle transport by foot traffic indoors.  

PubMed

Deposited particles are transported into and within buildings by adhering to and releasing from people's shoes. To better understand transport of deposited particulate contaminants and exposures to these materials, experimental data on tracking by foot traffic are needed. Laboratory experiments measured uptake and downlay mass transfer efficiencies of particles between shoes and floors in a step-simulation chamber. Equilibrium uptake transfer fractions, the net mass fraction transferred from floors to shoes after several steps, were also measured. Single-step uptake and downlay transfer efficiencies ranged from 0.02 to 0.22 and equilibrium uptake transfer fractions were 0.10-0.40. Particle size, particle loading, shoe type, floor type, step pressure, and step sequence were all investigated. Experiments demonstrated that single-step downlay transfer efficiencies decrease with each successive step onto clean floors. A simple empirical model is proposed to estimate these transfers as a function of step number. Simulations using the transfer efficiency values measured here illustrate the spread of deposited particles by people walking in a hypothetical hallway. These simulations show that in locations where a few people walk over the same area each minute, tracking can spread deposited material over length scales comparable to building dimensions in just a few hours. PMID:24579974

Sippola, Mark R; Sextro, Richard G; Thatcher, Tracy L

2014-04-01

80

Measuring Charge Transport in a Thin Solid Film Using Charge Sensing  

E-print Network

We measure charge transport in a hydrogenated amorphous silicon (a-Si:H) thin film using a nanometer scale silicon MOSFET as a charge sensor. This charge detection technique makes possible the measurement of extremely large ...

MacLean, Kenneth

81

The measurable heat flux that accompanies active transport Dick Bedeauxw and Signe Kjelstrupw  

E-print Network

The measurable heat flux that accompanies active transport by Ca2+ -ATPase Dick Bedeauxw and Signe of the fluxes far from global equilibrium. An asymmetric set of transport coefficients is obtained, by assuming how the measurable heat flux and the heat production under isothermal conditions, as well

Kjelstrup, Signe

82

Effect of sidewall conductance on heat-transport measurements for turbulent Rayleigh-Benard convection  

E-print Network

Effect of sidewall conductance on heat-transport measurements for turbulent Rayleigh, California 93106 Received 31 July 2000; published 27 December 2000 For measurements of turbulent heat transport in Rayleigh-Be´nard convection the correction for the sidewall conductance is usually neglected

Fygenson, Deborah Kuchnir

83

Indicators that matter : measuring transportation performance in Ahmedabad  

E-print Network

In light of the growing challenges of planning for transportation in India, this thesis proposes that a set of indicators, sensitive to local conditions, developed, implemented and managed through a collaborative partnership ...

Osborne, James Clark, M.C.P. Massachusetts Institute of Technology

2012-01-01

84

Noninvasive neutron scattering measurements reveal slower cholesterol transport in model lipid membranes.  

PubMed

Proper cholesterol transport is essential to healthy cellular activity and any abnormality can lead to several fatal diseases. However, complete understandings of cholesterol homeostasis in the cell remains elusive, partly due to the wide variability in reported values for intra- and intermembrane cholesterol transport rates. Here, we used time-resolved small-angle neutron scattering to measure cholesterol intermembrane exchange and intramembrane flipping rates, in situ, without recourse to any external fields or compounds. We found significantly slower transport kinetics than reported by previous studies, particularly for intramembrane flipping where our measured rates are several orders of magnitude slower. We unambiguously demonstrate that the presence of chemical tags and extraneous compounds employed in traditional kinetic measurements dramatically affect the system thermodynamics, accelerating cholesterol transport rates by an order of magnitude. To our knowledge, this work provides new insights into cholesterol transport process disorders, and challenges many of the underlying assumptions used in most cholesterol transport studies to date. PMID:21767489

Garg, S; Porcar, L; Woodka, A C; Butler, P D; Perez-Salas, U

2011-07-20

85

Noninvasive Neutron Scattering Measurements Reveal Slower Cholesterol Transport in Model Lipid Membranes  

PubMed Central

Proper cholesterol transport is essential to healthy cellular activity and any abnormality can lead to several fatal diseases. However, complete understandings of cholesterol homeostasis in the cell remains elusive, partly due to the wide variability in reported values for intra- and intermembrane cholesterol transport rates. Here, we used time-resolved small-angle neutron scattering to measure cholesterol intermembrane exchange and intramembrane flipping rates, in situ, without recourse to any external fields or compounds. We found significantly slower transport kinetics than reported by previous studies, particularly for intramembrane flipping where our measured rates are several orders of magnitude slower. We unambiguously demonstrate that the presence of chemical tags and extraneous compounds employed in traditional kinetic measurements dramatically affect the system thermodynamics, accelerating cholesterol transport rates by an order of magnitude. To our knowledge, this work provides new insights into cholesterol transport process disorders, and challenges many of the underlying assumptions used in most cholesterol transport studies to date. PMID:21767489

Garg, S.; Porcar, L.; Woodka, A.C.; Butler, P.D.; Perez-Salas, U.

2011-01-01

86

Measurement of the Copy Number of the Master Quorum-Sensing Regulator of a Bacterial Cell  

E-print Network

Measurement of the Copy Number of the Master Quorum-Sensing Regulator of a Bacterial Cell Shu, Princeton, New Jersey; and § Howard Hughes Medical Institute, Chevy Chase, Maryland ABSTRACT Quorum-sensing on parameters such as the copy number of particular quorum-sensing proteins should contribute strongly

Mehta, Pankaj

87

Measurements of Sediment Erosion and Transport with the ASSET Flume  

NASA Astrophysics Data System (ADS)

Soil and sediments play an important role in water management and water quality. Issues such as water turbidity, associated contaminants, reservoir sedimentation, undesirable erosion and scour, and aquatic habitat are all linked to sediment properties and behaviors. In situ analysis is necessary to develop an understanding of the erosion and transport of sediments. Sandia National Laboratories has recently patented the ASSET Flume that quantifies in situ erosion of a sediment core with depth while affording simultaneous examination of transport modes (bedload vs. suspended load) of the eroded material. Core erosion rates and ratios of bedload to suspended load transport of quartz sediments were studied with the ASSET Flume. The erosion and transport of a fine-grained natural cohesive sediment were also observed. Experiments using quartz sands revealed that the ratio of suspended load to bedload sediment transport is a function of grain diameter and shear stress at the sediment surface. Data collected from the ASSET Flume were used to formulate a novel empirical relation for predicting the ratio of bedload to suspended load as a function of shear stress and grain diameter for non-cohesive sediments.

Jepsen, R. A.; Roberts, J. D.; James, S. C.

2003-12-01

88

Application of electrochemical impedance measurements to corrosion prediction in the space transportation system launch environment  

SciTech Connect

Electrochemical Impedance Spectroscopy (EIS) measurements were performed to investigate the corrosion resistance of 18 alloys under conditions similar to the Space Transportation System (STS) launch environment. The UNS numbers of the alloys used were: R60702, N06022, N06625, N10276, N06455, N06600, S32950, S32550, N06985, N08020, N08904, N08825, S31603, S31703, S31803, S30403, N10665, and N04400. AC impedance data were gathered for all the alloys at various immersion tunes in aerated 3.55% NaCl-0.1N HCl. This electrolyte provides an environment for the corrosion of the alloys similar to conditions at the launch pad. Polarization resistance values were obtained from the Nyquist plot at each immersion time by curve fitting methods. N06022 showed the highest overall values for R{sub p} while N04400 and N06600 had the lowest overall values.

Calle, L.M. [Randolph-Macon Woman`s College, Lynchburg, VA (United States); MacDowell, L.G. III [NASA Materials Science Lab., Kennedy Space Center, FL (United States)

1994-12-31

89

Distance-Based Functional Diversity Measures and Their Decomposition: A Framework Based on Hill Numbers  

PubMed Central

Hill numbers (or the “effective number of species”) are increasingly used to characterize species diversity of an assemblage. This work extends Hill numbers to incorporate species pairwise functional distances calculated from species traits. We derive a parametric class of functional Hill numbers, which quantify “the effective number of equally abundant and (functionally) equally distinct species” in an assemblage. We also propose a class of mean functional diversity (per species), which quantifies the effective sum of functional distances between a fixed species to all other species. The product of the functional Hill number and the mean functional diversity thus quantifies the (total) functional diversity, i.e., the effective total distance between species of the assemblage. The three measures (functional Hill numbers, mean functional diversity and total functional diversity) quantify different aspects of species trait space, and all are based on species abundance and species pairwise functional distances. When all species are equally distinct, our functional Hill numbers reduce to ordinary Hill numbers. When species abundances are not considered or species are equally abundant, our total functional diversity reduces to the sum of all pairwise distances between species of an assemblage. The functional Hill numbers and the mean functional diversity both satisfy a replication principle, implying the total functional diversity satisfies a quadratic replication principle. When there are multiple assemblages defined by the investigator, each of the three measures of the pooled assemblage (gamma) can be multiplicatively decomposed into alpha and beta components, and the two components are independent. The resulting beta component measures pure functional differentiation among assemblages and can be further transformed to obtain several classes of normalized functional similarity (or differentiation) measures, including N-assemblage functional generalizations of the classic Jaccard, Sørensen, Horn and Morisita-Horn similarity indices. The proposed measures are applied to artificial and real data for illustration. PMID:25000299

Chiu, Chun-Huo; Chao, Anne

2014-01-01

90

Measured transonic unsteady pressures on an energy efficient transport wing with oscillating control surfaces  

NASA Technical Reports Server (NTRS)

Highlight results are presented from subsonic and transonic pressure measurement studies conducted in the Langley Transonic Dynamics Tunnel on a supercritical wing model representative of an energy efficient transport design. Steady- and unsteady-pressure data were acquired on the upper and lower wing surface at an off-design Mach number of 0.60 and at the design Mach number of 0.78, for a Reynolds number of 2.2 x 10(6) (based on the wing average chord). The model configuration consisted of a sidewall-Mounted half-body fuselage and a semi-span wing with an aspect ratio of 10.76, a leading-edge sweepback angle of 28.8 degrees, and supercritical airfoil sections. The wing is instrumented with 252 static pressure orifices and 164 dynamic pressure gages. Model test variables included wing angle of attack, control-surface mean deflection angle, control-surface oscillating deflection angle and frequency, and phasing between oscillating leading-edge and trailing-edge controls when used together.

Cazier, F. W., Jr.; Watson, J. J.; Doggett, R. V., Jr.; Sandford, M. C.; Ricketts, R. H.

1981-01-01

91

MOBILITY MEASUREMENT IN URBAN TRANSPORTATION (MMUT) RESEARCH PROJECT  

E-print Network

techniques such as cell phone tracking and global position satellite tracking are being used to gather phone tracking, global position satellite tracking, and on-board navigation devices. Some issues monitoring and transportation planning. These new and emerging data sources include such technologies as cell

92

Measuring the Value of Time in Highway Freight Transportation  

E-print Network

............................................................................................................ ix CHAPTER I INTRODUCTION AND BACKGROUND ................................................ 1 1.1. An Increasing Demand for Trucking ...................................................................... 1 1.2. Imbalance between Roadway Supply... .......................................................................... 99 Table 7.1: Summary of the Study ................................................................................... 102 1 CHAPTER I INTRODUCTION AND BACKGROUND 1.1. An Increasing Demand for Trucking Freight transportation is an important...

Miao, Qing

2014-01-13

93

Boundary-layer measurements on a high Reynolds number three-element airfoil  

NASA Technical Reports Server (NTRS)

An experimental investigation is being conducted to evaluate the boundary layer associated with a two-dimensional three-element single-flap airfoil at high Reynolds numbers. The present measurements are being made in the Langley Low-Turbulence (centerline turbulence intensity level is 0.034 percent at a Mach number of 0.2 and a total pressure of 60 psia) Pressure Tunnel (LTPT). The LTPT is a closed-circuit wind tunnel with a test section which is 3 ft wide, 7.5 ft high, and 7.5 ft long. Operating total pressure for the LTPT varies from 10 atmospheres to near-vacuum conditions. Tests are being conducted at a Mach number of 0.2 and Reynolds numbers (based on chord length) of 5, 9, and 16 million. Measurements include boundary-layer velocity surveys at several chordwise locations and surface skin-friction measurements using Preston tubes.

Selby, Gregory V.

1992-01-01

94

Accumulationmode aerosol number concentrations in the Arctic during the ARCTAS aircraft campaign: Longrange transport  

E-print Network

and Kazakhstan (Russian BB). Asian AN air had lower NLSP and TEN_LSP (25 cm-3 and 18% in spring and 6.2 cm-3 and 3.0% in summer) than Russian BB air (280 cm-3 and 97% in spring and 36 cm-3 and 7.6% in summer) due but 2.4­2.6 times less for Asian AN air in both spring and summer. This result shows that the transport

Jimenez, Jose-Luis

95

Accuracy of Florida Current Volume Transport Measurements at 278N Using Multiple Observational Techniques  

E-print Network

Accuracy of Florida Current Volume Transport Measurements at 278N Using Multiple Observational accuracy and precision. The three systems examined are dropsonde (free-falling float), lowered acoustic Doppler current profiler (LADCP), and submarine cable. The accuracy of the Florida Current transport

96

Direct in situ measurements of Li transport in Li-ion battery negative electrodes  

Microsoft Academic Search

We describe the first direct in situ measurements of Li transport in an operating cell. Motion of the lithiation front in the graphite electrode suggests that transport could be controlled by liquid-phase diffusion. The electrochemical (current–voltage) data are successfully modeled with a diffusion equation that contains no material or microstructural information. The model is only qualitatively successful in predicting observed

Stephen J. Harris; Adam Timmons; Daniel R. Baker; Charles Monroe

2010-01-01

97

Parallel Measurement and Modeling of Transport in the Darht II Beamline on ETA II  

Microsoft Academic Search

To successfully tune the DARHT II transport beamline requires the close coupling of a model of the beam transport and the measurement of the beam observables as the beam conditions and magnet settings are varied. For the ETA II experiment using the DARHT II beamline components this was achieved using the SUICIDE (Simple User Interface Connecting to an Integrated Data

F. W. Chambers; B. A. Raymond; S. Falabella; B. S. Lee; R. A. Richardson; J. T. Weir; H. A. Davis; M. E. Schultze

2005-01-01

98

Transport measurements from in-service undersea telephone cables  

Microsoft Academic Search

The motion of the ocean through the Earth's magnetic field creates a cross-stream voltage proportional to the transport of the stream. These motion-induced voltages have been observed for more than ten years by the use of an abandoned cable spanning the Florida Current. In-service undersea telephone cables, including fiber optic cables with branch lines, can also be used to determine

Jimmy C. Larsen

1991-01-01

99

Use of membrane vesicles to estimate the numbers of system y+ and system L amino acid transporters in human erythrocytes.  

PubMed Central

We have used equilibrium values for L-leucine and L-lysine uptake by right-side-out vesicles to estimate the membrane abundance (sites/cell) of Na(+)-dependent amino acid transport systems L and y+ in human erythrocytes. All of the intravesicular space was accessible to L-leucine, as judged by comparisons with uridine uptake via the equilibrative nucleoside transporter (10(4) sites/cell). In contrast, only 28% of the total intravesicular space was accessible to L-lysine uptake via system y+. Since human erythrocyte membranes generate an average of approximately 1000 vesicles/cell, these data provide evidence that system L is a relatively high-abundance membrane transport protein in human erythrocytes, while system y+ is present in smaller amounts (approximately 300 copies/cell). Calculated turnover numbers for L-lysine transport by system y+ at 37 degrees C are 24 s-1 for zero-trans influx and 150 s-1 for equilibrium-exchange influx. PMID:1907132

Tse, C M; Fincham, D A; Ellory, J C; Young, J D

1991-01-01

100

[Concrete pain prevention measures regarding hospital internal transport in a cancer center].  

PubMed

Iatrogenic pain is a common problem for cancer patients, including those due to hospital internal transport. An original prospective study conducted in 2006 allowed risk factor identification, and from 2007, a pluri-annual progress plan was implemented. Its actions were systematically evaluated and all phases of transportation reconsidered: preparation, patient transport to and care in medicotechnical units. Measures applied to anticipate these pains help improve the quality of hospital care. All professionals involved in the patient transportation system need to be made aware of this and not only hospital porters. PMID:23823980

Nebbak, Jean-Marie; Vignozzi, Annick; Bussy, Catherine; Charleux, Diane; Laplanche, Agnès; Mathivon, Delphine; Di Palma, Mario

2013-01-01

101

Laser transit-time measurements between earth and moon with a transportable system  

NASA Technical Reports Server (NTRS)

A high radiance, pulsed laser system with a transportable transmitting unit was used to measure the transit times of 25 ns, 10 joule, and 530 nm pulses from earth to the Apollo 15 retroreflector on the moon and back.

Lehr, C. G.; Criswell, S. J.; Ouellette, J. P.; Sozanski, P. W.; Mulholland, J. D.; Shelus, P. J.

1973-01-01

102

A Reynolds Number Study of Wing Leading-Edge Effects on a Supersonic Transport Model at Mach 0.3  

NASA Technical Reports Server (NTRS)

A representative supersonic transport design was tested in the National Transonic Facility (NTF) in its original configuration with small-radius leading-edge flaps and also with modified large-radius inboard leading-edge flaps. Aerodynamic data were obtained over a range of Reynolds numbers at a Mach number of 0.3 and angles of attack up to 16 deg. Increasing the radius of the inboard leading-edge flap delayed nose-up pitching moment to a higher lift coefficient. Deflecting the large-radius leading-edge flap produced an overall decrease in lift coefficient and delayed nose-up pitching moment to even higher angles of attack as compared with the undeflected large- radius leading-edge flap. At angles of attack corresponding to the maximum untrimmed lift-to-drag ratio, lift and drag coefficients decreased while lift-to-drag ratio increased with increasing Reynolds number. At an angle of attack of 13.5 deg., the pitching-moment coefficient was nearly constant with increasing Reynolds number for both the small-radius leading-edge flap and the deflected large-radius leading-edge flap. However, the pitching moment coefficient increased with increasing Reynolds number for the undeflected large-radius leading-edge flap above a chord Reynolds number of about 35 x 10 (exp 6).

Williams, M. Susan; Owens, Lewis R., Jr.; Chu, Julio

1999-01-01

103

In-Situ Measurements of Engineered Nanoporous Particle Transport in Saturated Porous Media  

SciTech Connect

Engineered nanoporous particles have become an important class of nano-structured materials that have found their increasing industrial, energy, and environmental applications. The internal pore surfaces in the particles can be chemically tailored to sequestrate metals and radionuclide contaminants from groundwater. The fate and transport of the nanoporous particles in subsurface environments, however, have not been studied. Here we present a scanning optical fiber fluorescence profiler that can be used to in situ measure the transport of fluorescence-tagged colloidal and nano-structured particles in column systems. Engineered nanoporous silicate particles (ENSPs) that were covalently bonded with fluorescence-emitting, and uranium-chelating ligands in the intraparticle pore domains were synthesized and used as an example to investigate the nanoporous particle transport and to demonstrate the application of the developed in situ measurement profiler. The profiler detected an irreversible or slowly detached fraction of ENSPs in the sand collector even under conditions thermodynamically unfavorable to particle attachment. Further, the in situ measurement system detected the spatial variability of ENSPs transport that deviated from one-dimensional, homogeneous assumption that is typically used to model particle transport in the column. Generally, however, both measured and model-calculated results indicated that the transport of ENSPs were consistent with that of nonporous colloidal particles that subjected to coupled reversible attachment/detachment and straining processes. The developed system can also be applied to detect other fluorescence-tagged nano-structured or colloidal particle transport.

Shang, Jianying; Liu, Chongxuan; Wang, Zheming; Wu, Hong; Zhu, Kake; Li, Juan; Liu, Jun

2010-10-28

104

Measurements of the dependence of the photon-number distribution on the number of modes in parametric down-conversion.  

PubMed

Optical parametric down-conversion (PDC) is a central tool in quantum optics experiments. The number of collected down-converted modes greatly affects the quality of the produced photon state. We use Silicon Photomultiplier (SiPM) number-resolving detectors in order to observe the photon-number distribution of a PDC source, and show its dependence on the number of collected modes. Additionally, we show how the stimulated emission of photons and the partition of photons into several modes determine the overall photon number. We present a novel analytical model for the optical crosstalk effect in SiPM detectors, and use it to analyze the results. PMID:22330466

Dovrat, L; Bakstein, M; Istrati, D; Shaham, A; Eisenberg, H S

2012-01-30

105

Measurements of the dependence of the photon-number distribution on the number of modes in parametric down-conversion  

E-print Network

Optical parametric down-conversion (PDC) is a central tool in quantum optics experiments. The number of collected down-converted modes greatly affects the quality of the produced photon state. We use Silicon Photomultiplier (SiPM) number-resolving detectors in order to directly observe the photon-number distribution of a PDC source, and show its dependence on the number of collected modes. Additionally, we show how the stimulated emission of photons and the partition of photons into several modes determine the overall photon number. We present a novel analytical model for the optical crosstalk effect in SiPM detectors, and use it to analyze the results.

L. Dovrat; M. Bakstein; D. Istrati; A. Shaham; H. S. Eisenberg

2012-01-03

106

Effects of droplet interactions on droplet transport at intermediate Reynolds numbers  

NASA Technical Reports Server (NTRS)

Effects of droplet interactions on drag, evaporation, and combustion of a planar droplet array, oriented perpendicular to the approaching flow, are studied numerically. The three-dimensional Navier-Stokes equations, with variable thermophysical properties, are solved using finite-difference techniques. Parameters investigated include the droplet spacing, droplet Reynolds number, approaching stream oxygen concentration, and fuel type. Results are obtained for the Reynolds number range of 5 to 100, droplet spacings from 2 to 24 diameters, oxygen concentrations of 0.1 and 0.2, and methanol and n-butanol fuels. The calculations show that the gasification rates of interacting droplets decrease as the droplet spacings decrease. The reduction in gasification rates is significant only at small spacings and low Reynolds numbers. For the present array orientation, the effects of interactions on the gasification rates diminish rapidly for Reynolds numbers greater than 10 and spacings greater than 6 droplet diameters. The effects of adjacent droplets on drag are shown to be small.

Shuen, Jian-Shun

1987-01-01

107

Effects of droplet interactions on droplet transport at intermediate Reynolds numbers  

NASA Technical Reports Server (NTRS)

Effects of droplet interactions on drag, evaporation, and combustion of a planar droplet array, oriented perpendicular to the approaching flow, are studied numerically. The three-dimensional Navier-Stokes equations, with variable thermophysical properties, are solved using finite-difference techniques. Parameters investigated include the droplet spacing, droplet Reynolds number, approaching stream oxygen concentration, and fuel type. Results are obtained for the Reynolds number range of 5 to 100, droplet spacing from 2 to 24 diameters, oxygen concentrations of 0.1 and 0.2, and methanol and n-butanol fuels. The calculations show that the gasification rates of interacting droplets decrease as the droplet spacings decrease. The reduction in gasification rates is significant only at small spacings and low Reynolds numbers. For the present array orientation, the effects of interactions on the gasification rates diminish rapidly for Reynolds numbers greater than 10 and spacings greater than 6 droplet diameters. The effects of adjacent droplets on drag are shown to be small.

Shuen, J. S.

1986-01-01

108

Asymptotic estimates for the number of contingency tables, integer flows, and volumes of transportation polytopes  

E-print Network

We prove an estimate for the number of mxn non-negative integer matrices (contingency tables) with prescribed row and column sums within a factor of N^{O(m+n)}, where N is the total sum of the matrix entries and, more generally, for the number of integer feasible flows in a network. Similarly, we estimate the volume of the polytope of mxn non-negative real matrices with prescribed row and column sums within a factor of N^{O(m+n)}. Our estimates are solutions of convex optimization problems and hence can be computed efficiently. As a corollary, we show that if the row and column sums are sufficiently generic, then the intuitive ``independence heuristic'' underestimates the number of tables as badly as within a factor of gamma^{mn} for some constant gamma>1. Our main tools are an estimate for the volume of a section of a simplex by a subspace of a small codimension and an integral representation for the number of contingency tables.

Barvinok, Alexander

2007-01-01

109

Velocity measurements in a high-Reynolds-number, momentum-conserving, axisymmetric, turbulent jet  

Microsoft Academic Search

The turbulent flow resulting from a top-hat jet exhausting into a large room was investigated. The Reynolds number based on exit conditions was approximately 10(exp 5). Velocity moments to third order were obtained using flying and stationary hot-wire and burst-mode laser-Doppler anemometry (LDA) techniques. The entire room was fully seeded for the LDA measurements. The measurements are shown to satisfy

Hussein J. Hussein; Steven P. Capp; William K. George

1994-01-01

110

Measurement of plasma current dependent changes in impurity transport and comparison with nonlinear gyrokinetic simulation  

SciTech Connect

Measured impurity transport coefficients are found to demonstrate a strong dependence on plasma current in the core of Alcator C-Mod. These measurements are compared directly with linear and nonlinear gyrokinetic simulation in an attempt to both qualitatively and quantitatively reproduce the measured impurity transport. Discharges constituting a scan of plasma current from 0.6 to 1.2 MA were performed during the 2010 run campaign. The impurity transport from these discharges was determined using a novel set of spectroscopic diagnostics available on Alcator C-Mod. This diagnostic suite allowed for the effective constraint of impurity transport coefficient profiles inside of r/a = 0.6. A decrease in the measured impurity diffusivity and inward convection is found with increased plasma current. Global, nonlinear gyrokinetic simulations were performed using the GYRO code [J. Candy and R. E. Waltz, J Comput. Phys. 186, 545 (2003)] for all discharges in the experimental scan and are found to reproduce the experimental trends, while demonstrating good quantitative agreement with measurement. A more comprehensive quantitative comparison was performed on the 0.8 MA discharge of the current scan which demonstrates that simultaneous agreement between experiment and simulation in both the impurity particle transport and ion heat transport channels is attainable within experimental uncertainties.

Howard, N. T.; Greenwald, M.; White, A. E.; Reinke, M. L.; Ernst, D.; Podpaly, Y. [MIT-Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Mikkelsen, D. R. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Candy, J. [General Atomics, San Diego, California 92186 (United States)

2012-05-15

111

Air transport flight parameter measurements program - Concepts and benefits  

NASA Technical Reports Server (NTRS)

A program is described in which statistical flight loads and operating practice data for both narrow- and wide-body airline transport aircraft, intended primarily for use by manufacturers in updating design criteria, are obtained from existing, on-board digital flight data recorders. Procedures for editing and processing the data are explained, and differences between these and past NACA/NASA analog data are discussed. One major such difference is the automatic bandpass filtering of normal acceleration data to separate high-frequency gust response from low-frequency maneuver response. Plans and preliminary efforts for the development of an on-board data processing system, able to derive statistical aircraft operating parameters directly from real-time data, are also reviewed.

Morris, G. J.; Crabill, N. L.

1980-01-01

112

Measurement of the Copy Number of the Master Quorum-Sensing Regulator of a Bacterial Cell  

NASA Astrophysics Data System (ADS)

Quorum sensing is the mechanism by which bacteria communicate and synchronize group behaviors. Quantitative information on parameters such as the copy number of particular quorum-sensing proteins should contribute strongly to understanding how the quorum-sensing network functions. Here we show that the copy number of the master regulator protein LuxR in Vibrio harveyi, can be determined in vivo by exploiting small-number fluctuations of the protein distribution when cells undergo division. When a cell divides, both its volume and LuxR protein copy number N are partitioned with slight asymmetries. We have measured the distribution functions describing the partitioning of the protein fluorescence and the cell volume. The fluorescence distribution is found to narrow systematically as the LuxR population increases while the volume partitioning is unchanged. Analyzing these changes statistically, we have determined that N = 80-135 dimers at low cell density and 575 dimers at high cell density. In addition, we have measured the static distribution of LuxR over a large (3,000) clonal population. Combining the static and time-lapse experiments, we determine the magnitude of the Fano factor of the distribution. This technique has broad applicability as a general, in vivo technique for measuring protein copy number and burst size.

Teng, Shu-Wen; Wang, Yufang; Tu, Kimberly C.; Long, Tao; Mehta, Pankaj; Wingreen, Ned S.; Bassler, Bonnie L.; Ong, N. P.

2010-05-01

113

Continuous measurements of bedload transport rates in a small glacial river catchment in the summer season (Spitsbergen)  

NASA Astrophysics Data System (ADS)

The study on bedload transport was conducted on the gravel-bed Scott River catchment with a glacial alimentation regime, located in the NW part of the Wedel Jarlsberg Land (Spitsbergen) with subpolar climatic conditions. In the melt season of 2010, bedload transport rate was continuously monitored at 24-hour intervals by means of four River Bedload Trap devices aligned across the width of the channel. The maximum bedload transport rate varied strongly at portions of the cross section from 16 to 152 kg m- 1 d- 1 in cross-profile I (c-p I) and 4 to 125 kg m- 1 d- 1 in cross-profile II (c-p II). The maximum channel-mean bedload transport rate (qa) amounted to 54 kg m- 1 d- 1 (c-p I) and 35 kg m- 1 d- 1 (c-p II). Mean daily bedload discharge (Qb) was estimated at a level of 97 kg day- 1 (c-p I) and 35 kg m- 1 d- 1 (c-p II), and the total bedload yield was determined at approx. 4345 kg in the measurement period (2086 kg — c-p I; 2203 kg — c-p II from 13.07 to 10.08). The analysis of the relationship between channel-mean bedload transport rate and water velocity or shear stress revealed a significant value of the correlation coefficient (R2 = 0.6). Discharge and rate of bedload transport were dependent on the weather and number of days with flood discharge. Approx. 58% of the entire discharged bedload was transported during 3 violent ablation-precipitation floods. Bedload grain size distribution was right-skewed and showed moderate sorting.

Kociuba, Waldemar; Janicki, Grzegorz

2014-05-01

114

Modeling Source Contributions to Submicron Particle Number Concentrations Measured in Rochester, New York  

Microsoft Academic Search

An advanced receptor model was used to elicit source information based on ambient submicron (0.01–0.47 ?m) particle number concentrations, gaseous species, and meteorological variables measured at the New York State Department of Environmental Conservation central monitoring site in Rochester, NY. Four seasonal data sets (winter, spring, summer, and fall) were independently investigated. A total of ten different sources were identified,

David Ogulei; Philip K. Hopke; David C. Chalupa; Mark J. Utell

2007-01-01

115

Estimates of Entropy Numbers and Gaussian Measures for Classes of Functions with Bounded Mixed Derivative  

Microsoft Academic Search

The paper contains estimates for the entropy numbers of classes of functions with conditions on the mixed derivative (difference), in the uniform and integral metrics. As an application, the new estimates of the Gaussian measure of a small ball are obtained.

E. S. Belinsky

1998-01-01

116

Measuring Physical Activity with Pedometers in Older Adults with Intellectual Disability: Reactivity and Number of Days  

ERIC Educational Resources Information Center

The minimum number of days of pedometer monitoring needed to estimate valid average weekly step counts and reactivity was investigated for older adults with intellectual disability. Participants (N = 268) with borderline to severe intellectual disability ages 50 years and older were instructed to wear a pedometer for 14 days. The outcome measure

Hilgenkamp, Thessa; Van Wijck, Ruud; Evenhuis, Heleen

2012-01-01

117

Absorption Measurements of 4s State Number density for a Microwave Argon Plasma  

NASA Astrophysics Data System (ADS)

Optical emission and continuum measurements have been performed to characterize microwave argon plasmas. A Wavemat (model MPDR-3135) microwave diamond deposition system was used to generate the argon plasma at 5 Torr with an argon flow rate of 300 sccm. In a previous study, three excited states number densities (4p, 5p, and 5d) were obtained from the emission measurements. These data were used to validate our zero-dimensional (with diffusion) Collisional-Radiative Model (CRM) by matching these three excited state number densities with the prediction from the CRM. An energy balance study showed that the energy absorbed by the argon plasma was far less than the reading from the power meters, also in agreement with our CRM predictions. To better characterize the plasma, we have recently measured the 4s population through absorption at 7635Å. The light source was a low-pressure AC argon lamp. To calculate the 4s number density, the lineshapes of the argon lamp and the argon plasma are needed. The lineshape of the argon lamp was taken from previous work which used a similar lamp. However, the plasma lineshape depends on the electron number density, the number densities of related excited states, the electron and gas temperatures, etc. For our microwave plasma system, these parameters cannot be measured directly. Therefore, the plasma lineshape was calculated based on the parameters predicted from the CRM. The 4s state number density calculted from this lineshape matches the predicted one from the CRM within the experimental uncertainty, further validating our model.

Li, Yunlong; Gordon, Matthew; Roe, Larry; Hassouni, Khaled

1999-10-01

118

Multi-bit quantum random number generation by measuring positions of arrival photons.  

PubMed

We report upon the realization of a novel multi-bit optical quantum random number generator by continuously measuring the arrival positions of photon emitted from a LED using MCP-based WSA photon counting imaging detector. A spatial encoding method is proposed to extract multi-bits random number from the position coordinates of each detected photon. The randomness of bits sequence relies on the intrinsic randomness of the quantum physical processes of photonic emission and subsequent photoelectric conversion. A prototype has been built and the random bit generation rate could reach 8 Mbit/s, with random bit generation efficiency of 16 bits per detected photon. FPGA implementation of Huffman coding is proposed to reduce the bias of raw extracted random bits. The random numbers passed all tests for physical random number generator. PMID:25362380

Yan, Qiurong; Zhao, Baosheng; Liao, Qinghong; Zhou, Nanrun

2014-10-01

119

Multi-bit quantum random number generation by measuring positions of arrival photons  

NASA Astrophysics Data System (ADS)

We report upon the realization of a novel multi-bit optical quantum random number generator by continuously measuring the arrival positions of photon emitted from a LED using MCP-based WSA photon counting imaging detector. A spatial encoding method is proposed to extract multi-bits random number from the position coordinates of each detected photon. The randomness of bits sequence relies on the intrinsic randomness of the quantum physical processes of photonic emission and subsequent photoelectric conversion. A prototype has been built and the random bit generation rate could reach 8 Mbit/s, with random bit generation efficiency of 16 bits per detected photon. FPGA implementation of Huffman coding is proposed to reduce the bias of raw extracted random bits. The random numbers passed all tests for physical random number generator.

Yan, Qiurong; Zhao, Baosheng; Liao, Qinghong; Zhou, Nanrun

2014-10-01

120

An automated system for selective and continuous measurements of vertical Thoron profiles for the determination of transport times near the ground  

NASA Astrophysics Data System (ADS)

The quantification of in-canopy transport times is of a~major importance for the investigation of sources, sinks and net fluxes of reactive trace gases within plant canopies. The Damköhler number, which compares timescales of chemical reactions with transport times, is a widely applied measure to evaluate flux divergences. In this study, we present and evaluate a novel automated measurement system for selective vertical Thoron (Tn) profiles near the earth's surface and demonstrate its suitability for the direct and reliable determination of transport times within a natural grassland canopy. For the first time, we perform a rigorous determination of systematic and random uncertainties of Tn (and Rn) concentrations under field conditions for this type of measurement system. The obtained median precisions for three concentration classes (> 100 Bq m-3, 100-15 Bq m-3 < 15 Bq m-3) were 8.8%, 23.2% and 132.1% for Tn (and 16.6%, 25.0%, 99.2% for Rn). We calculate in-canopy transport times (?) and propagate it's uncertainty from the individual errors of the Tn concentration measurements. A quality assessment of ? for the field experiment revealed a good data quality with 44% of the relative uncertainties below 50%. The occurrence of transport time uncertainties higher than 100% was caused by absolute Tn gradients lower than 70 Bq m-3, which was found for 22% of all determined transport times. In addition, the method was found to be highly sensitive to the Tn concentrations at the upper of two inlet heights (zu). Low values of CTnzu result in high absolute uncertainties of the transport time. A comparison of the measured ? with empirical parameterizations revealed the lowest scatter for the measured ? values. We found an excellent agreement of ? with transport times obtained by the in-canopy resistance approach used, e.g. in the SURFATM model during daytime, while the SURFATM model significantly overestimated transport times during nighttime.

Plake, D.; Trebs, I.

2013-01-01

121

Measurement precision guarantees efficient accounting and saving of oil products. [Tiraspol' motor-transport establishments  

Microsoft Academic Search

The managers of the Tiraspol' motor-transport establishments and enterprises were forced to adopt effective measures for regulating the measurement, registration, and storage of oil products. Savings were realized by improving the measuring equipment's utilization, reorganizing the system for dispensing oil products, replacing old filling stations, and installing remote-control fuel-filling pumps. These measures resulted in profits amounting to 543,000 rubles in

V. V. Tikhonov; N. A. Yurtaev

1975-01-01

122

Spectroscopic measurements of plasma temperatures and electron number density in a uranium hollow cathode discharge lamp  

NASA Astrophysics Data System (ADS)

The plasma parameters including neutral species temperature, atomic excitation temperature and electron number density in a see-through type, homemade uranium hollow cathode discharge lamp with neon as a buffer gas have been investigated using optical emission spectroscopic techniques. The neutral species temperature has been measured using the Doppler broadening of a neon atomic spectral line. The atomic excitation temperature has been measured using the Boltzmann plot method utilizing uranium atomic spectral lines. The electron number density has been determined from the Saha-Boltzmann equation utilizing uranium atomic and ionic spectral lines. To the best of our knowledge, all these three plasma parameters are simultaneously measured for the first time in a uranium hollow cathode discharge lamp.

Shah, M. L.; Suri, B. M.; Gupta, G. P.

2015-01-01

123

PARALLEL MEASUREMENT AND MODELING OF TRANSPORT IN THE DARHT II BEAMLINE ON ETA II  

SciTech Connect

To successfully tune the DARHT II transport beamline requires the close coupling of a model of the beam transport and the measurement of the beam observables as the beam conditions and magnet settings are varied. For the ETA II experiment using the DARHT II beamline components this was achieved using the SUICIDE (Simple User Interface Connecting to an Integrated Data Environment) data analysis environment and the FITS (Fully Integrated Transport Simulation) model. The SUICIDE environment has direct access to the experimental beam transport data at acquisition and the FITS predictions of the transport for immediate comparison. The FITS model is coupled into the control system where it can read magnet current settings for real time modeling. We find this integrated coupling is essential for model verification and the successful development of a tuning aid for the efficient convergence on a useable tune. We show the real time comparisons of simulation and experiment and explore the successes and limitations of this close coupled approach.

Chambers, F W; Raymond, B A; Falabella, S; Lee, B S; Richardson, R A; Weir, J T; Davis, H A; Schultze, M E

2005-05-31

124

Atmospheric effects on infrared measurements at ground level: Application to monitoring of transport infrastructures  

NASA Astrophysics Data System (ADS)

Being able to perform easily non-invasive diagnostics for surveillance and monitoring of critical transport infrastructures is a major preoccupation of many technical offices. Among all the existing electromagnetic methods [1], long term thermal monitoring by uncooled infrared camera [2] is a promising technique due to its dissemination potential according to its low cost on the market. Nevertheless, Knowledge of environmental parameters during measurement in outdoor applications is required to carry out accurate measurement corrections induced by atmospheric effects at ground level. Particularly considering atmospheric effects and measurements in foggy conditions close as possible to those that can be encountered around transport infrastructures, both in visible and infrared spectra. In the present study, atmospheric effects are first addressed by using data base available in literature and modelling. Atmospheric attenuation by particles depends greatly of aerosols density, but when relative humidity increases, water vapor condenses onto the particulates suspended in the atmosphere. This condensed water increases the size of the aerosols and changes their composition and their effective refractive index. The resulting effect of the aerosols on the absorption and scattering of radiation will correspondingly be modified. In a first approach, we used aerosols size distributions derived from Shettle and Fenn [3] for urban area which could match some of experimental conditions encountered during trials on transport infrastructures opened to traffic. In order to calculate the influence of relative humidity on refractive index, the Hänel's model [4] could be used. The change in the particulate size is first related to relative humidity through dry particle radius, particle density and water activity. Once the wet aerosol particle size is found, the effective complex refractive index is the volume weighted average of the refractive indexes of the dry aerosol substance and the water. These changes in refractive indexes lead to the evolution of extinction coefficient Kext according to relative humidity. Using such models in very low visibility conditions leads to the following question: Up to which optical depth (i.e. tau=Kext.d) can we use a simple scattering model as Mie Theory? To show the effect of multiple scattering on previous transmission estimation, Monte-Carlo calculations have been performed. Calculations used a software dedicated to photometrical rendering of fog (PROF [5]). Up to an optical depth tau=1, simple and multiple scatterings differ of less than 2%. For tau >1 the simple scattering model is no more available to keep the error less than 10%. Finally, study of fog effect is proposed. Results obtained by numerical simulations but also by experiments carried out in a dedicated fog tunnel are presented and discussed. Perspectives about possible implementation on on site measurement systems are evocated. REFERENCES [1]Proto M. et al., , 2010. Transport infrastructure surveillance and monitoring by electromagnetic sensing: the ISTIMES project. Sensors, 10,10620-10639, doi: 10.3390/s101210620. [2]J. Dumoulin, A. Crinière, R. Averty ," Detection and thermal characterization of the inner structure of the "Musmeci" bridge deck by infrared thermography monitoring ",Journal of Geophysics and Engineering, Volume 10, Number 2, November 2013, IOP Science, doi:10.1088/1742-2132/10/6/064003. [3]Shettle. P. and Fenn R. W., "Models for the aerosols of the lower atmosphere and the effects of humidity variations on their optical properties", Air Force Geophysics Laboratory 79-0214, (1979). [4]30. Hänel, Gottfried, "The properties of atmospheric aerosol particles as functions of the relarive humidity at thermodynamic equilibrium with the surrounding moist air, in Advances in Geophysics, 73-188. Edited by H.E. Landsberg, and J. Van Mieghem, Academic Press, New York, 1976. [5]31. Dumont E., "Semi-Monte Carlo light tracing applied to the study of road visibility in fog", In Monte Ca

Boucher, Vincent; Dumoulin, Jean

2014-05-01

125

Measuring urea persistence, distribution and transport on coastal plain soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

The persistence and mobility of urea, an organic form of nitrogen present in animal manures and commercial fertilizers, has rarely been studied and measured, because it is assumed to undergo rapid hydrolysis to ammonia. However, preliminary studies have shown urea to exist in leachate and runoff sev...

126

Effect of sidewall conductance on heat-transport measurements for turbulent Rayleigh-Bénard convection  

Microsoft Academic Search

For measurements of turbulent heat transport in Rayleigh-Bénard convection the correction for the sidewall conductance is usually neglected or based on measurements or estimates for the empty cell. It is argued that the lateral thermal coupling between the fluid and the wall can invalidate these approaches, and that corrections based on calculations of the two-dimensional temperature fields are required in

Guenter Ahlers

2001-01-01

127

Tabulated pressure measurements on a large subsonic transport model airplane with high bypass ratio, powered, fan jet engines  

NASA Technical Reports Server (NTRS)

An experimental wind-tunnel investigation to determine the aerodynamic interference and the jet-wake interference associated with the wing, pylon, and high-bypass-ratio, powered, fan-jet model engines has been conducted on a typical high-wing logistics transport airplane configuration. Pressures were measured on the wing and pylons and on the surfaces of the engine fan cowl, turbine cowl, and plug. Combinations of wing, pylons, engines, and flow-through nacelles were tested, and the pressure coefficients are presented in tabular form. Tests were conducted at Mach numbers from 0.700 to 0.825 and angles of attack from -2 to 4 deg.

Flechner, S. G.; Patterson, J. C., Jr.

1972-01-01

128

Thermal Transport Measurement of Silicon-Germanium Nanowires  

E-print Network

of thermal resistance circuit for thermal conductivity measurement?????????.????...?... 15 FIGURE 9 The resistance(Rs(I=0)) of the PRT as a function of temperature.... 21 FIGURE 10 Temperature variation on each membrane for SiGe nanowire 3 at 300K... Resistance of heating membrane PRT s R Resistance of sensing membrane PRT h Q Joule heat on heating membrane PRT l Q Joule heat on heating membrane leg h T Temperature on heating membrane 0 T Environmental temperature s T Temperature...

Gwak, Yunki

2010-10-12

129

PIV measurements of water mist transport in a homogeneous turbulent flow past an obstacle  

Microsoft Academic Search

To obtain a better understanding of the physical processes involved in liquid suppressant transport in cluttered spaces, particle image velocimetry (PIV) measurements were carried out in the droplet-laden, grid-generated, homogeneous turbulent flow over both an unheated and heated cylinder, and a body-centered cube (BCC) arrangement of spheres. Transport of both water droplets and aerosol particles was characterized upstream and downstream

Cary Presser; George Papadopoulos; John F. Widmann

2006-01-01

130

Structure dependent energy transport: relaxation-assisted 2DIR measurements and theoretical studies.  

PubMed

Vibrational energy relaxation and transport in a molecule that is far from thermal equilibrium can affect its chemical reactivity. Understanding the energy transport dynamics in such molecules is also important for measuring molecular structural constraints via relaxation-assisted two-dimensional infrared (RA 2DIR) spectroscopy. In this paper we investigated vibrational relaxation and energy transport in the ortho, meta, and para isomers of acetylbenzonitrile (AcPhCN) originated from excitation of the CN stretching mode. The amplitude of the cross-peak among the CN and CO stretching modes served as an indicator for the energy transport from the CN group toward the CO group. A surprisingly large difference is observed in both the lifetimes of the CN mode and in the energy transport rates for the three isomers. The anharmonic DFT calculations and energy transport modeling performed to understand the origin of the differences and to identify the main cross-peak contributors in these isomers described well the majority of the experimental results including mode excited-state lifetimes and the energy transport dynamics. The strong dependence of the energy transport on molecular structure found in this work could be useful for recognizing different isomers of various compounds via RA 2DIR spectroscopy. PMID:21859144

Kasyanenko, Valeriy M; Tesar, Sarah L; Rubtsov, Grigory I; Burin, Alexander L; Rubtsov, Igor V

2011-09-29

131

In-flight pressure distributions and skin-friction measurements on a subsonic transport high-lift wing section  

NASA Technical Reports Server (NTRS)

Flight experiments are being conducted as part of a multiphased subsonic transport high-lift research program for correlation with wind-tunnel and computational results. The NASA Langley Transport Systems Research Vehicle (B737-100 aircraft) is used to obtain in-flight flow characteristics at full-scale Reynolds numbers to contribute to the understanding of 3-D high-lift, multi-element flows including attachment-line transition and relaminarization, confluent boundary-layer development, and flow separation characteristics. Flight test results of pressure distributions and skin friction measurements were obtained for a full-chord wing section including the slat, main-wing, and triple-slotted, Fowler flap elements. Test conditions included a range of flap deflections, chord Reynolds numbers (10 to 21 million), and Mach numbers (0.16 to 0.40). Pressure distributions were obtained at 144 chordwise locations of a wing section (53-percent wing span) using thin pressure belts over the slat, main-wing, and flap elements. Flow characteristics observed in the chordwise pressure distributions included leading-edge regions of high subsonic flows, leading-edge attachment-line locations, slat and main-wing cove-flow separation and reattachment, and trailing-edge flap separation. In addition to the pressure distributions, limited skin-friction measurements were made using Preston-tube probes. Preston-tube measurements on the slat upper surface suggested relaminarization of the turbulent flow introduced by the pressure belt on the slat leading-edge surface when the slat attachment line was laminar. Computational analysis of the in-flight pressure measurements using two-dimensional, viscous multielement methods modified with simple-sweep theory showed reasonable agreement. However, overprediction of the pressures on the flap elements suggests a need for better detailed measurements and improved modeling of confluent boundary layers as well as inclusion of three-dimensional viscous effects in the analysis.

Yip, Long P.; Vijgen, Paul M. H. W.; Hardin, Jay D.; Vandam, C. P.

1993-01-01

132

Electrophysiological measurement of the number of rhodopsin molecules in single Limulus photoreceptors  

PubMed Central

Two partly independent electrophysiological methods are described for measuring the number of rhodopsin molecules (R) in single ventral photoreceptors. Method 1 is based on measurements of the relative intensity required to elicit a quantal response and the relative intensity required to half-saturate the early receptor potential (ERP). Method 2 is based on measurements of the absolute intensity required to elicit a quantal response. Both methods give values of R approximately equal to 10(9). From these and other measurements, estimates are derived for the surface density of rhodopsin (8,000/micrometer2), the charge movement during the ERP per isomerized rhodopsin (20 X 10(-21) C), and the half-time for thermal isomerization of rhodopsin (36yr). PMID:591915

1977-01-01

133

Cloud liquid water, mean droplet radius, and number density measurements using a Raman lidar  

SciTech Connect

A new technique for measuring cloud liquid water, mean droplet radius, and droplet number density is outlined. The technique is based on simultaneously measuring Raman and Mie scattering from cloud liquid droplets using a Raman lidar. Laboratory experiments on liquid microspheres have shown that the intensity of Raman scattering is proportional to the amount of liquid present in the spheres. This fact is used as a constraint on calculated Mie intensity assuming a gamma function particle size distribution. The resulting retrieval technique is shown to give stable solutions with no false minima. It is tested using Raman lidar data where the liquid water signal was seen as an enhancement to the water vapor signal. The general relationship of retrieved average radius and number density is consistent with traditional cloud physics models. Sensitivity to the assumed maximum cloud liquid water amount and the water vapor mixing ratio calibration are tested. Improvements to the technique are suggested. (c) 1999 American Geophysical Union.

Whiteman, David N. [Laser Remote Sensing Branch, NASA Goddard Space Flight Center, Greenbelt, Maryland (United States)] [Laser Remote Sensing Branch, NASA Goddard Space Flight Center, Greenbelt, Maryland (United States); Melfi, S. Harvey [Department of Physics, University of Maryland, Baltimore County, Baltimore (United States)] [Department of Physics, University of Maryland, Baltimore County, Baltimore (United States)

1999-12-27

134

MEASUREMENTS AND COMPUTATIONS OF FUEL DROPLET TRANSPORT IN TURBULENT FLOWS  

SciTech Connect

The objective of this project is to study the dynamics of fuel droplets in turbulent water flows. The results are essential for development of models capable of predicting the dispersion of slightly light/heavy droplets in isotropic turbulence. Since we presently do not have any experimental data on turbulent diffusion of droplets, existing mixing models have no physical foundations. Such fundamental knowledge is essential for understanding/modeling the environmental problems associated with water-fuel mixing, and/or industrial processes involving mixing of immiscible fluids. The project has had experimental and numerical components: 1. The experimental part of the project has had two components. The first involves measurements of the lift and drag forces acting on a droplet being entrained by a vortex. The experiments and data analysis associated with this phase are still in progress, and the facility, constructed specifically for this project is described in Section 3. In the second and main part, measurements of fuel droplet dispersion rates have been performed in a special facility with controlled isotropic turbulence. As discussed in detail in Section 2, quantifying and modeling the of droplet dispersion rate requires measurements of their three dimensional trajectories in turbulent flows. To obtain the required data, we have introduced a new technique - high-speed, digital Holographic Particle Image Velocimetry (HPIV). The technique, experimental setup and results are presented in Section 2. Further information is available in Gopalan et al. (2005, 2006). 2. The objectives of the numerical part are: (1) to develop a computational code that combines DNS of isotropic turbulence with Lagrangian tracking of particles based on integration of a dynamical equation of motion that accounts for pressure, added mass, lift and drag forces, (2) to perform extensive computations of both buoyant (bubbles) and slightly buoyant (droplets) particles in turbulence conditions relevant to the experiments, and (3) to explore whether the corresponding predictions can explain the experimentally-observed behavior of the rise and dispersion of oil droplets in isotropic turbulence. A brief summary of results is presented in Section 4.

Joseph Katz and Omar Knio

2007-01-10

135

Density and atomic number measurements with spectral x-ray attenuation method  

NASA Astrophysics Data System (ADS)

X-ray attenuation measurements are widely used in medical and industrial applications. The usual results are one- to three-dimensional representations of the attenuation coefficient ?(r). In this paper, we present the ?Z projection algorithm for obtaining the density ?(r) and atomic number Z(r) with an energy-resolving x-ray method. As input data the algorithm uses at least two measurements ?1,?2,… with different spectral weightings of the source spectrum S(E) and/or detector sensitivity D(E). Analytically, ? is a function of ?1-c?2, c=const, and Z is a function of ?1/?2. The full numerical treatment yields ?(?1,?2) and Z(?1,?2) with S(E) and D(E) as commutative parametric functions. We tested the method with dual-energy computed tomography measurements of an organic sample and a set of chemical solutions with predefined ? and Z. The resulting images show ? and Z as complementary information: The density ? reflects the morphology of the objects, whereas the atomic number Z=number of electrons/atom describes the material distribution. For our experimental setup we obtain an absolute precision of 0.1 for Z and 20 mg/cm3 for ?. The ?Z projection can potentially lead to these classes of quantitative information for various scientific, industrial, and medical applications.

Heismann, B. J.; Leppert, J.; Stierstorfer, K.

2003-08-01

136

Deformation of an elastic body in low Reynolds number transport: Relevance to biofilm deformation and streamer formation  

E-print Network

In this paper, we obtain analytical results for shear stress distributions inside an elastic body placed in a low Reynolds number transport. The problem definition is inspired by a recent experimental study (Valiei et al., Lab Chip, 2012, 12, 5133-5137) that reports the flow-triggered deformation of bacterial biofilms, formed on cylindrical rigid microposts, into long filamentous structures known as streamers. In our analysis, we consider an elastic body of finite thickness (forming a rim) placed over a rigid cylinder, i.e., we mimic the biofilm structure in the experiment. We consider Oseen flow solution to describe the low Reynolds transport past this cylindrical elastic structure. The stress and strain distributions inside the elastic structure are found to be functions of position, Poisson ratio, initial thickness of the elastic rim and the ratio of the flow-driven shear stress to the shear modulus of the elastic body. More importantly, these analyses, which can be deemed as one of the first formal analys...

Gupta, Nikhil; Mitra, Sushanta K; Kumar, Aloke

2015-01-01

137

Influence of Lewis number on the surface density function transport in the thin reaction zone regime for turbulent premixed flames  

NASA Astrophysics Data System (ADS)

The effects of tangential strain rate and curvature on the surface density function (SDF) and on different terms within the SDF transport equation in the thin reaction zone regime are studied for statistically planar turbulent premixed flames with global Lewis numbers Le =0.8, 1.0, and 1.2 by using three-dimensional direct numerical simulations with simplified chemistry. A positive correlation is observed between the SDF and tangential strain rate, and this is explained in terms of the local statistical behaviors of tangential strain rate and dilatation rate. Curvature is shown to affect the SDF through the curvature response of both tangential strain rate and dilatation rate on a given flame isosurface. The correlation between the curvature and SDF is positive in the Le =0.8 flame and negative in the Le =1.2 flame. The curvature dependence of the SDF is weak in the case of unity Lewis number. Strain rate and curvature are found to have an appreciable effect on different terms of the SDF transport equation. The SDF strain rate term arising from tangential strain rate contribution in all the flames is positively correlated with tangential strain rate as expected and is also negatively correlated with curvature. For the Le =1.0 and 1.2 flames, the SDF propagation term is found to negatively correlate with flame curvature toward the reactant side of the flame and positively toward the product side. By contrast, for the Le =0.8 flame, the SDF propagation term is negatively correlated with curvature throughout the flame brush. The variation of the SDF curvature term with local flame curvature for all the flames is found to be nonlinear due to the additional stretch induced by the tangential diffusion component of the displacement speed. Physical explanations are provided for all of these effects, and the modeling implications are discussed in detail.

Chakraborty, Nilanjan; Klein, Markus

2008-06-01

138

Measurement of the transport spin polarization of FeV using point-contact Andreev reflection  

SciTech Connect

The Fe1 xVx alloy system exhibits the lowest known Gilbert relaxation rate of any ferromagnetic metal or binary alloy with G1 435MHz at x1 427% V. Low relaxation rates are of particular interest in modern spin electronic applications involving spin torque. The transport spin polarization of a series of sputtered epitaxial Fe1 xVx samples was measured using point contact Andreev reflection. Values of the transport spin polarization agree well with those measured for pure Fe and are independent of composition. The results indicate that the substitution of up to 50% of V for Fe does not reduce the spin polarization in the alloy.

Bailey, William [Columbia University; Osofsky, Mike [Naval Research Laboratory, Washington, D.C.; Bussman, Konrad [Naval Research Laboratory, Washington, D.C.; Parker, David S [ORNL; Cheng, L [Columbia University

2013-01-01

139

Spin transport and precession in graphene measured by nonlocal and three-terminal methods  

SciTech Connect

We investigate the spin transport and precession in graphene by using the Hanle effect in nonlocal and three-terminal measurement geometries. Identical spin lifetimes, spin diffusion lengths, and spin polarizations are observed in graphene devices for both techniques over a wide range of temperatures. The magnitude of the spin signals is well explained by spin transport models. These observations rules out any signal enhancements or additional scattering mechanisms at the interfaces for both geometries. This validates the applicability of both the measurement methods for graphene based spintronics devices and their reliable extractions of spin parameters.

Dankert, André, E-mail: andre.dankert@chalmers.se; Kamalakar, Mutta Venkata; Bergsten, Johan; Dash, Saroj P., E-mail: saroj.dash@chalmers.se [Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296 Göteborg (Sweden)

2014-05-12

140

The measurable heat flux that accompanies active transport by Ca2+-ATPase.  

PubMed

We present a new mesoscopic basis which can be used to derive flux equations for the forward and reverse mode of operation of ion-pumps. We obtain a description of the fluxes far from global equilibrium. An asymmetric set of transport coefficients is obtained, by assuming that the chemical reaction as well as the ion transports are activated, and that the enzyme has a temperature independent of the activation coordinates. Close to global equilibrium, the description reduces to the well known one from non-equilibrium thermodynamics with a symmetric set of transport coefficients. We show how the measurable heat flux and the heat production under isothermal conditions, as well as thermogenesis, can be defined. Thermogenesis is defined via the onset of the chemical reaction or ion transports by a temperature drop. A prescription has been given for how to determine transport coefficients on the mesocopic level, using the macroscopic coefficient obtained from measurements, the activation enthalpy, and a proper probability distribution. The method may give new impetus to a long-standing unsolved transport problem in biophysics. PMID:19060976

Bedeaux, Dick; Kjelstrup, Signe

2008-12-28

141

The Influence of Atmospheric Transport Regimes on Polychlorinated Biphenyl (PCB) Concentrations Measured at Zeppelin  

NASA Astrophysics Data System (ADS)

Polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) of exclusively anthropogenic origin. PCBs are toxic, bioaccumulative and have a great potential of long-range transport. PCBs have been banned globally under the Stockholm convention on POPs since 2004. We analysed times series of 21 PCB congeners ranging from PCB 18 to PCB 187 that have been measured at Zeppelin (Spitsbergen) since 1993. Although primary PCB emissions have been steadily reduced, a strong decreasing trend is not observed in the PCB concentrations in the Arctic. In order to investigate the influence of atmospheric transport on the PCB concentrations and to identify the potential source regions of the PCBs, we calculated footprints for the Zeppelin measurement site using the Lagrangian Particle Dispersion Model FLEXPART. Footprints can be interpreted as potential source regions where PCBs may have been picked up. Based on various statistical analyses of the footprints (cluster analysis, k-medoid, silhouette), we identified the prevailing transport regimes for Zeppelin which were represented by 5 different clusters. Cluster 1 and 3 belong to transport regimes with highest residence times over Europe (cluster 1) and North-America (cluster 3); both transport regimes dominantly occur from late fall to early spring. Clusters 2 and 4 represent air masses with surface contact predominantly over the Atlantic Ocean (cluster 2), only occurring during the summer months, and the Arctic Ocean (cluster 4) mainly observed in spring and autumn, but also in summer. Cluster 5 is representative of air originating from the Pacific ocean and eastern Asia; this transport regime occurs mainly in spring and fall. We grouped the PCB concentrations measured at Zeppelin according to the 5 different clusters and calculated the median for each cluster and PCB congener. The median for medium to heavier PCBs is highest for cluster 1 and 3, which represent transport regimes over the continent, suggesting that emissions of the respective PCBs dominantly occur over land. However, for the lighter congeners (PCB-18-PCB-47) the highest median concentration corresponds to cluster 2 and the lowest to cluster 3 and 5. The high concentration of the lighter congeners resulting from the transport over the ocean, represented by clusters 2 and to some extent 4, cannot be explained by primary PCB emissions. Also the use of a temperature-dependent primary PCB emission inventory did not resolve this apparent contradiction between high PCB concentrations and a transport regime under which Zeppelin does not receive air from the continents. Our data therefore suggest that in addition to atmospheric transport regimes and primary PCB emissions, also other factors such as secondary emissions from the ocean and/or from soils strongly influence the concentrations of lighter PCBs measured at Zeppelin.

Ubl, S.; Scheringer, M.; Hungerbuehler, K.

2013-12-01

142

An automated system for selective and continuous measurements of vertical thoron profiles for the determination of transport times near the ground  

NASA Astrophysics Data System (ADS)

The quantification of in-canopy transport times is of major importance for the investigation of sources, sinks and net fluxes of reactive trace gases within plant canopies. The Damköhler number, which compares timescales of chemical reactions with transport times, is a widely applied measure to evaluate flux divergences. In this study we present and evaluate a novel automated measurement system for selective vertical thoron (Tn) profiles near the Earth's surface and demonstrate its suitability for the direct and reliable determination of transport times within a natural grassland canopy. For the first time, we perform a rigorous determination of systematic and random uncertainties of Tn (and Rn) concentrations under field conditions for this type of measurement system. The obtained median precisions for three concentration classes (> 100 Bq m-3, 100-15 Bq m-3, < 15 Bq m-3) were 8.8%, 23.2% and 132.1% for Tn (and 16.6%, 25.0%, 99.2% for Rn). We calculate in-canopy transport times (?) and propagate their uncertainty from the individual errors of the Tn concentration measurements. A quality assessment of ? for the field experiment during a period of 51 days revealed good data quality with 44% of the relative uncertainties below 50%. The occurrence of transport time uncertainties higher than 100% was caused by absolute Tn gradients lower than 70 Bq m-3 m-1, which was found for 22% of all determined transport times. In addition, the method was found to be highly sensitive to the Tn concentrations at the upper of the two inlet heights (zu). Low values of CTnzu result in high absolute uncertainties of the transport time. A comparison with empirical parameterizations revealed a much lower scatter for the ? values determined from our measurements. We found an excellent agreement with ? values obtained by the in-canopy resistance approach used, e.g., in the SURFATM model during daytime, while the SURFATM model significantly overestimated transport times during nighttime.

Plake, D.; Trebs, I.

2013-04-01

143

Particle concentrations and number size distributions in the planetary boundary layer derived from airship based measurements  

NASA Astrophysics Data System (ADS)

Atmospheric particles play a key role for regional and global climate due to their direct and indirect radiative forcing effects. The concentration and size of the particles are important variables to these effects. Within the continental planetary boundary layer (PBL) the particle number size distribution is influenced by meteorological parameters, local sinks and sources resulting in variable spatial distributions. However, measurements of particle number size distributions over a broad vertical range of the PBL are rare. The airship ZEPPELIN NT is an ideal platform to measure atmospheric aerosols on a regional scale within an altitude range up to 1000 m. For campaigns in the Netherlands, Northern Italy and South Finland in 2012 and 2013 the airship was deployed with a wide range of instruments, including measurements of different trace gases, short lived radicals, solar radiation, aerosols and meteorological parameters. Flights were carried out at different times of the day to investigate the influence of the diurnal evolution of the PBL on atmospheric trace gases and aerosols. During night and early morning hours the concentration and size distribution of atmospheric particles were found to be strongly influenced by the layered structure of the PBL, i.e. the nocturnal boundary layer and the residual layer. Within the residual layer particle concentrations stay relatively constant as this layer is decoupled from ground sources. The particles persist in the accumulation mode as expected for an aged aerosol. In the nocturnal boundary layer particle concentrations and size are more dynamic with higher concentrations than in the residual layer. A few hours after sunrise, the layered structure of the PBL intermixes. During daytime the PBL is well mixed and a negative concentration gradient with increasing height is observed. Several height profiles at different times of the day and at different locations in Europe were measured. The aerosol measurements will be discussed together with meteorological parameters and trace gas measurements. Acknowledgement: PEGASOS project funded by the European Commission and the Framework Program 7 (FP7-ENV-2010-265148).

Tillmann, Ralf; Zhao, Defeng; Ehn, Mikael; Hofzumahaus, Andreas; Holland, Frank; Rohrer, Franz; Kiendler-Scharr, Astrid; Wahner, Andreas

2014-05-01

144

Mobile lidar system for measurement of water vapor mixing ratio and ozone number density  

NASA Technical Reports Server (NTRS)

The Water Vapor Lidar was modified and extended to make differential absorption measurements of ozone. Water vapor measurements make use of a weak molecular scattering process known as Raman scattering. It is characterized by a shift in wavelength of the scattered beam of light relative to the incident one. Some of the energy of the incident photon is converted to vibrational or rotational energy within the molecule leaving the scattered photon shifted to a slightly longer wavelength. When performing water vapor measurements, profiles are acquired of water vapor mixing ratio from near the ground to beyond 7 km every 2 minutes. By forming a color composite image of the individual profiles, the spatial and temporal evolution of water vapor is visible with vertical resolution of 75 to 150m and temporal resolution of 2 minutes. The ozone lidar is intended for use as a cross calibration facility for other stationary ozone lidar systems. The ozone measurement employs the technique known as differential absorption. The backscattered laser radiation from two different wavelengths is measured. Successful measurements of 308 nm returns were made from 80 km with an averaging period of 6 hours. Using these data and a standard atmosphere density curve, an ozone number density profile was made which agrees very well with the standard ozone curve between 20 and 40 km.

Whiteman, D.

1988-01-01

145

Challenges in Measuring and Predicting Medium Term (Weeks to Annual) Aeolian Sediment Transport in Beach-Dune Systems  

NASA Astrophysics Data System (ADS)

Coastal dune budgets depend on sediment input by wind from the beach. Calculation of aeolian transport is thus a primary factor to understand coastal dune evolution and beach-dune coupled dynamics. However, measuring aeolian sediment transport in coastal areas presents fundamental technical and conceptual limitations that make numerical modeling difficult. Wind tunnel experiments isolate and reduce the number of variables to study, which is a necessary procedure to clearly manifest mechanistic relationships between cause and effect. But even with refinement and inclusion of new variables, traditional sediment transport formulas derived from wind tunnel experiments do not usually work well in natural areas. Short-term experiments may include precise instrumentation to obtain high frequency, detail time series of variables involved in aeolian transport, but inferring information at larger scales is problematic without knowledge of the timing and magnitude of particular transport events. There are two primary problems in attempting to predict sediment inputs to coastal dunes over periods of weeks, months or years: 1) to determine an appropriate set of predictive equations that incorporate complexities such as surface moisture content, beach width and the presence of vegetation; and 2) to provide quantitative data on these variables for input into the model at this time scale. Remote sensing techniques and the use of GIS software open the possibility to monitor key parameters regulating sediment transport dynamics at high spatial and temporal resolution over time scales beyond short-term experiments. These were applied at Greenwich Dunes, Prince Edward Island National Park (Canada), in an attempt to measure factors affecting aeolian sediment input to the foredune at a medium scale. Three digital cameras covering different sections of the beach and foredune provide time series on shoreline position, fetch distances, vegetation cover, ice/snow presence, or superficial moisture content. The rectification of oblique images to UTM maps allows to keep the spatial variability of these factors, and thus to perform detailed analysis on their complex evolution. Auxiliary instrumentation such as anemometers, safires, or erosion-deposition pins completes the basic set up. Data is processed using ArcGIS 9.2 and PCI Geomatica 9.1, and managed by an ArcCatalog Geodatabase. The coupling of new technologies (digital imagery) with traditional instrumentation (e.g. anemometers), and the extensive GIS capabilities both in the spatial and temporal domain, permits a new set of questions in aeolian coastal research. The overall goal is to obtain information on what is the frequency and magnitude of transport events at the beach or what are the key parameters regulating them. Challenges remain in improving methodologies to measure sediment transport rates. Ironically enough, we are able to obtain high quality time series on the factors affecting aeolian transport at the beach, but actual transport rates are measured with rather rudimentary techniques or instrumentation not adapted to meso-scale monitoring. This information is needed to test new approaches in modeling and understanding aeolian sediment input from the beach to the foredunes.

Delgado-Fernandez, I.

2009-05-01

146

Laboratory measurements of the transport of radon gas through concrete samples.  

PubMed

Experiments were conducted to measure the transportability of radon gas through common concrete samples which were characterized by their mix proportions, dimensions, porosity, air permeability, and radon gas diffusion coefficient. Several innovative test systems and methods were designed, fabricated, and calibrated to accurately measure these radon gas transport characteristics for concrete and to overcome many of the shortcomings of previously published experimental works. From the experimental results, it was found that diffusion is the dominant transport mechanism by which radon gas moves through an intact concrete slab. It was also shown that indoor radon entry rates can be greatly affected by the type of concrete mix employed. The results of this study can be utilized to improve the present technology of radon-resistant construction techniques for new residential construction. PMID:7759258

Renken, K J; Rosenberg, T

1995-06-01

147

Markstein Numbers of Negatively-Stretched Premixed Flames: Microgravity Measurements and Computations  

NASA Technical Reports Server (NTRS)

The effect of flame stretch, composed of strain and curvature, plays a major role in the propagation of turbulent premixed flames. Although all forms of stretch (positive and negative) are present in turbulent conditions, little research has been focused on the stretch due to curvature. The present study quantifies the Markstein number (which characterizes the sensitivity of the flame propagation speed to the imposed stretch rate) for an inwardly-propagating flame (IPF). This flame is of interest because it is negatively stretched, and is subjected to curvature effects alone, without the competing effects of strain. In an extension of our previous work, microgravity experiments were run using a vortex-flame interaction to create a pocket of reactants surrounded by an IPF. Computations using the RUN-1DL code of Rogg were also performed in order to explain the measurements. It was found that the Markstein number of an inwardly-propagating flame, for both the microgravity experiment and the computations, is significantly larger than that of an outwardly-propagating flame. Further insight was gained by running the computations for the simplified (hypothetical) cases of one step chemistry, unity Lewis number, and negligible heat release. Results provide additional evidence that the Markstein numbers associated with strain and curvature have different values.

Ibarreta, Alfonso F.; Driscoll, James F.; Feikema, Douglas A.; Salzman, Jack (Technical Monitor)

2001-01-01

148

Accurate Measurement of Mitochondrial DNA Deletion Level and Copy Number Differences in Human Skeletal Muscle  

PubMed Central

Accurate and reliable quantification of the abundance of mitochondrial DNA (mtDNA) molecules, both wild-type and those harbouring pathogenic mutations, is important not only for understanding the progression of mtDNA disease but also for evaluating novel therapeutic approaches. A clear understanding of the sensitivity of mtDNA measurement assays under different experimental conditions is therefore critical, however it is routinely lacking for most published mtDNA quantification assays. Here, we comprehensively assess the variability of two quantitative Taqman real-time PCR assays, a widely-applied MT-ND1/MT-ND4 multiplex mtDNA deletion assay and a recently developed MT-ND1/B2M singleplex mtDNA copy number assay, across a range of DNA concentrations and mtDNA deletion/copy number levels. Uniquely, we provide a specific guide detailing necessary numbers of sample and real-time PCR plate replicates for accurately and consistently determining a given difference in mtDNA deletion levels and copy number in homogenate skeletal muscle DNA. PMID:25474153

Blakely, Emma L.; Haller, Ronald G.; Taylor, Robert W.; Turnbull, Doug M.; Tuppen, Helen A. L.

2014-01-01

149

High spatial range velocity measurements in a high Reynolds number turbulent boundary layer  

NASA Astrophysics Data System (ADS)

Here, we detail and analyse a multi-resolution particle image velocity measurement that resolves the wide range of scales prevalent in a zero pressure gradient turbulent boundary layer at high Reynolds numbers (up to Re? ? 20 000). A unique configuration is utilised, where an array of eight high resolution cameras at two magnification levels are used simultaneously to obtain a large field of view, while still resolving the smaller scales prevalent in the flow. Additionally, a highly magnified field of view targeted at the near wall region is employed to capture the viscous sublayer and logarithmic region, with a spatial resolution of a few viscous length scales. Flow statistics from these measurements show good agreement with prior, well resolved hot-wire anemometry measurements. Analysis shows that the instantaneous wall shear stress can be reliably computed, which is historically known to be challenging in boundary layers. A statistical assessment of the wall shear stress shows good agreement with existing correlations, prior experimental and direct numerical simulation data, extending this view to much higher Reynolds numbers. Furthermore, conditional analysis using multiple magnification levels is detailed, to study near-wall events associated with high skin friction fluctuations and their associated overlaying structures in the log region. Results definitively show that the passage of very large-scale positive (or negative) velocity fluctuations are associated with increased (or reduced) small-scale variance in wall shear stress fluctuations.

de Silva, C. M.; Gnanamanickam, E. P.; Atkinson, C.; Buchmann, N. A.; Hutchins, N.; Soria, J.; Marusic, I.

2014-02-01

150

Measurement and modeling of ultrafast carrier dynamics and transport in germanium/silicon-  

E-print Network

Measurement and modeling of ultrafast carrier dynamics and transport in germanium/silicon- germanium quantum wells Stephanie A. Claussen,1,3,* Emel Tasyurek,1,3 Jonathan E. Roth, 1,2 and David A. B. S. Harris, and D. A. B. Miller, Optical modulator on silicon employing germanium quantum wells, Opt

Miller, David A. B.

151

Thermoelectric and Magnetothermoelectric Transport Measurements of Graphene Yuri M. Zuev,1  

E-print Network

Thermoelectric and Magnetothermoelectric Transport Measurements of Graphene Yuri M. Zuev,1 Willy, USA (Received 7 December 2008; published 6 March 2009) The conductance and thermoelectric power (TEP of thermal and thermoelectric prop- erties of this two-dimensional material [2­8], only an indirect

Kim, Philip

152

Towards a Modal Shift in Freight Transport? A Business Logistics Analysis of Some Policy Measures  

Microsoft Academic Search

This paper analyses the effectiveness of policy measures aimed at triggering a modal shift in the freight transport market. The analysis is based on the inventory?theoretic framework that studies modal choice from a business logistics viewpoint. The crux of the inventory?theoretic approach lies in the fact that explicit attention is paid to all costs in the supply chain that are

Gust Blauwens; Nico Vandaele; Eddy Van de Voorde; Bert Vernimmen; Frank Witlox

2006-01-01

153

Stochastic transport theory for investigating the three-dimensional canopy structure from space measurements  

E-print Network

Stochastic transport theory for investigating the three-dimensional canopy structure from space vegetation canopies exhibits high spatial variation. Satellite-borne sensors measure the mean intensities the most logical linkage between satellite observations and the three-dimensional canopy structure through

Goldberg, Bennett

154

Examining injection properties of boreal forest fires using surface and satellite measurements of CO transport  

Microsoft Academic Search

Boreal forest fires are highly variable in space and time and also have variable vertical injection properties. We compared a University of Maryland Chemistry and Transport Model (UMD-CTM) simulation of boreal forest fire CO in the summer of 2000 to surface observations from the NOAA Cooperative Air Sampling Network and satellite observations of CO from the Measurement of Pollutants in

Edward J. Hyer; Dale J. Allen; Eric S. Kasischke

2007-01-01

155

Oxygen transport in zeolite Y measured by quenching of encapsulated tris(bipyridyl)ruthenium  

E-print Network

Oxygen transport in zeolite Y measured by quenching of encapsulated tris(bipyridyl)ruthenium Abstract This study deals with emission quenching of zeolite encapsulated trisbipyridyl ruthenium (II) (Ru the migration of O2 within zeolites using the emis- sion quenching of zeolite encapsulated ruthenium

Dutta, Prabir K.

156

DIRECT MEASUREMENT OF FAST AXONAL ORGANELLE TRANSPORT IN THE SCIATIC NERVE OF RATS TREATED WITH ACRYLAMIDE  

EPA Science Inventory

The effects of acrylamide on fast axonal transport have been measured primarily using the indirect methods of isotope or enzyme accumulation. e report the first direct evaluation of the effects of sub-chronic acrylamide dosing (150, 300 or 500 mg/kg total dose) on the fast axonal...

157

Testing the scaling of thermal transport models: predicted and measured temperatures in the Tokamak Fusion Test  

E-print Network

scaling experiments are expected to reveal the physically signi#12;cant parametric dependences of plasmaTesting the scaling of thermal transport models: predicted and measured temperatures in the Tokamak Fusion Test Reactor dimensionless scaling experiments D. R. Mikkelsen, S. D. Scott Princeton

158

Fabrication and electric-field-dependent transport measurements of mesoscopic graphite devices  

E-print Network

Fabrication and electric-field-dependent transport measurements of mesoscopic graphite devices micromechanical method to extract extremely thin graphite samples. Graphite crystallites with thicknesses ranging from 10 to 100 nm and lateral size 2 m are extracted from bulk. Mesoscopic graphite devices

Cobden, David

159

Uncertainty in Cloud Aerosol Transport System (CATS) Doppler Lidar Products and Measurements  

Microsoft Academic Search

The Cloud Aerosol Transport System (CATS) is both a high spectral resolution lidar and Doppler lidar currently being developed at NASA Goddard Space Flight Center for use as a demonstrator instrument for NASA's Aerosol Cloud Ecosystem (ACE) Mission. CATS is intended to fly on NASA's high-altitude ER-2 aircraft. CATS will be capable of measuring both aerosol properties and horizontal wind

P. A. Selmer

2010-01-01

160

Using Travel Time Reliability Measures to Improve Regional Transportation Planning and URS Corporation  

E-print Network

Using Travel Time Reliability Measures to Improve Regional Transportation Planning and Operations revised from original submittal. #12;Lyman and Bertini 2 Abstract. Travel time estimation is of increasing. In fact, the reliability of travel time estimates on a given corridor may be more important for travelers

Bertini, Robert L.

161

INFLUENCE OF INTERFACE CHARGES ON TRANSPORT MEASUREMENTS IN AMORPHOUS SILICON FILMS  

E-print Network

E 1241 INFLUENCE OF INTERFACE CHARGES ON TRANSPORT MEASUREMENTS IN AMORPHOUS SILICON FILMS I-of-states amorphous silicon can be explained by the effect of a variable charge density at the film Classification Physics Abstracts 73.40Q--71.25M It has been found that hydrogenated amorphous silicon prepared

Paris-Sud XI, Université de

162

Lagrangian Transport Model Forecasts as Useful Support of the Flight Planning During the Intercontinental Transport and Chemical Transformation 2002 (ITCT 2k2) Measurement Campaign  

Microsoft Academic Search

In this study, the Lagrangian tracer transport model FLEXPART is shown to be a useful forecasting tool for the flight planning during the ITCT 2k2 (Intercontinental Transport and Chemical Transformation 2002) aircraft measurement campaign. The advantages of this model are that it requires only a short computation time, has a finer spatial resolution and does not suffer numerical diffusion compared

C. Forster; O. Cooper; A. Stohl; S. Eckhardt; P. James; E. Dunlea; D. K. Nicks; J. S. Holloway; G. Hübler; D. D. Parrish; T. B. Ryerson

2002-01-01

163

Improvement of Pulping Uniformity by Measurement of Single Fiber Kappa Number  

SciTech Connect

A method to measure the kappa of single fibers by staining with a fluorescent dye, Acridine Orange (AO), has been developed. This method is now applied to develop and automated flow-through instrument that permits routine kappa analysis on thousands of images of AO stained fibers to give the fiber kappa number distribution of a pulp sample in a few minutes. The design and operation of the instrument are similar to that of a flow cytometer but with the addition of extensive fiber imaging capability. Fluorescence measurements in the flow-through instrument are found to be consistent with those made with fluorescence microscope provided the signal processing in the flow-thou instrument is handled propertly. The kappa distributions of pulps that were analyzed by means of a density gradient column are compared to those measured with the flow-through instrument with good results. The kappa distributions of various laboratory pulps and commercial pulps have been measured. It has been found that all pulps are non-uniform but that ommercial pulps generally have broader kappa distributions thatn their laboratory counterparts. The effects of different pulping methods and chip pretreatments on pulp uniformity are discussed in the report. Finally, the application of flow-through fluorescence technology to other single fiber measurements are presented.

Richard R. Gustafson; James B. Callis

2001-11-20

164

Measurements of the effect of a magnetic field on the transport of linear momentum in nitrogen  

E-print Network

MEASUREMENTS OF THE EFFECT OF A MAGNETIC FIELD ON THE TRANSPORT OF LINEAR MOMENTUM IN NITROGEN A Thesis By MARK EDWARD LARCHEZ Submitted to the Graduate College of the Texas A&M University in partial fulfillment of the requirements... Introduction II Related Work The Senftleben Effect The Scott Effect III Experimental Method: Apparatus and Procedure IV Measurements and Results 14 Bibliography 22 LIST OF FIGURES 1. Schematic of Apparatus 2. Approach to Saturation 3. New Data...

Larchez, Mark Edward

1968-01-01

165

GIS measured environmental correlates of active school transport: A systematic review of 14 studies  

Microsoft Academic Search

Background  Emerging frameworks to examine active school transportation (AST) commonly emphasize the built environment (BE) as having\\u000a an influence on travel mode decisions. Objective measures of BE attributes have been recommended for advancing knowledge about\\u000a the influence of the BE on school travel mode choice. An updated systematic review on the relationships between GIS-measured\\u000a BE attributes and AST is required to

Bonny Yee-Man Wong; Guy Faulkner; Ron Buliung

2011-01-01

166

A directional quantifying Doppler system for measurement of transport velocity of blood.  

PubMed

A transcutaneous Doppler device has been developed that measures primarily the directional transport velocity of blood, averaged over the vessel diameter, irrespective of its flow in adjacent vessels. Directional information is obtained by high or low-pass filtering of frequency converted versions of the received Doppler signals, applying low-cost, sharp filters in a superheterodyne system. Upper and lower channel signals are quantified separately to average directional velocity. Linear results from in vitro measurements are obtained. PMID:1138476

De Jong, D A; Megens, P H; De Vlieger, M; Thön, H; Holland, W P

1975-05-01

167

The Experimental Measurement of Aerodynamic Heating About Complex Shapes at Supersonic Mach Numbers  

NASA Technical Reports Server (NTRS)

In 2008 a wind tunnel test program was implemented to update the experimental data available for predicting protuberance heating at supersonic Mach numbers. For this test the Langley Unitary Wind Tunnel was also used. The significant differences for this current test were the advances in the state-of-the-art in model design, fabrication techniques, instrumentation and data acquisition capabilities. This current paper provides a focused discussion of the results of an in depth analysis of unique measurements of recovery temperature obtained during the test.

Neumann, Richard D.; Freeman, Delma C.

2011-01-01

168

Cryptographic random number generators for low-power distributed measurement system  

NASA Astrophysics Data System (ADS)

In this paper we present the State of The Art in Cryptographic Random Number Generators (RNG). We provide analysis of every of the most popular types of RNGs such as linear generators (i.e. congruential, multiple recursive), non-linear generators (i.e. Quadratic, Blum-Blum-Shub) and cryptographic algorithms based (i.e. RSA generator, SHA-1 generator). Finally we choose solutions which are suitable to Distributed Measurement Systems (DMS) specific requirements according to cryptographic security, computational efficiency (throughput) and complexity of implementation (VHDL targeted at FPGA and ASIC devices). Strong asymmetry of computing power and memory capacity is taken into account in both software and hardware solutions.

Czernik, Pawel; Olszyna, Jakub

2009-06-01

169

Measurement of carrier transport and recombination parameter in heavily doped silicon  

NASA Technical Reports Server (NTRS)

The minority carrier transport and recombination parameters in heavily doped bulk silicon were measured. Both Si:P and Si:B with bulk dopings from 10 to the 17th and 10 to the 20th power/cu cm were studied. It is shown that three parameters characterize transport in bulk heavily doped Si: the minority carrier lifetime tau, the minority carrier mobility mu, and the equilibrium minority carrier density of n sub 0 and p sub 0 (in p-type and n-type Si respectively.) However, dc current-voltage measurements can never measure all three of these parameters, and some ac or time-transient experiment is required to obtain the values of these parameters as a function of dopant density. Using both dc electrical measurements on bipolar transitors with heavily doped base regions and transients optical measurements on heavily doped bulk and epitaxially grown samples, lifetime, mobility, and bandgap narrowing were measured as a function of both p and n type dopant densities. Best fits of minority carrier mobility, bandgap narrowing and lifetime as a function of doping density (in the heavily doped range) were constructed to allow accurate modeling of minority carrier transport in heavily doped Si.

Swanson, Richard M.

1986-01-01

170

Characterization of the transport properties of channel delta-doped structures by light-modulated Shubnikov-de Haas measurements  

NASA Technical Reports Server (NTRS)

The transport properties of channel delta-doped quantum well structures were characterized by conventional Hall effect and light-modulated Shubnikov-de Haas (SdH) effect measurements. The large number of carriers that become available due to the delta-doping of the channel, leads to an apparent degeneracy in the well. As a result of this degeneracy, the carrier mobility remains constant as a function of temperature from 300 K down to 1.4 K. The large amount of impurity scattering, associated with the overlap of the charge carriers and the dopants, resulted in low carrier mobilities and restricted the observation of the oscillatory magneto-resistance used to characterize the two-dimensional electron gas (2DEG) by conventional SdH measurements. By light-modulating the carriers, we were able to observe the SdH oscillation at low magnetic fields, below 1.4 tesla, and derive a value for the quantum scattering time. Our results for the ratio of the transport and quantum scattering times are lower than those previously measured for similar structures using much higher magnetic fields.

Mena, R. A.; Schacham, S. E.; Haugland, E. J.; Alterovitz, S. A.; Young, P. G.; Bibyk, S. B.; Ringel, S. A.

1995-01-01

171

The effective number density of galaxies for weak lensing measurements in the LSST project  

NASA Astrophysics Data System (ADS)

Future weak lensing surveys potentially hold the highest statistical power for constraining cosmological parameters compared to other cosmological probes. The statistical power of a weak lensing survey is determined by the sky coverage, the inverse of the noise in shear measurements and the galaxy number density. The combination of the latter two factors is often expressed in terms of neff - the `effective number density of galaxies used for weak lensing measurements'. In this work, we estimate neff for the Large Synoptic Survey Telescope (LSST) project, the most powerful ground-based lensing survey planned for the next two decades. We investigate how the following factors affect the resulting neff of the survey with detailed simulations: (1) survey time, (2) shear measurement algorithm, (3) algorithm for combining multiple exposures, (4) inclusion of data from multiple filter bands, (5) redshift distribution of the galaxies and (6) masking and blending. For the first time, we quantify in a general weak lensing analysis pipeline the sensitivity of neff to the above factors. We find that with current weak lensing algorithms, expected distributions of observing parameters, and all lensing data (r and i band, covering 18 000 degree2 of sky) for LSST, neff ? 37 arcmin-2 before considering blending and masking, neff ? 31 arcmin-2 when rejecting seriously blended galaxies and neff ? 26 arcmin-2 when considering an additional 15 per cent loss of galaxies due to masking. With future improvements in weak lensing algorithms, these values could be expected to increase by up to 20 per cent. Throughout the paper, we also stress the ways in which neff depends on our ability to understand and control systematic effects in the measurements.

Chang, C.; Jarvis, M.; Jain, B.; Kahn, S. M.; Kirkby, D.; Connolly, A.; Krughoff, S.; Peng, E.-H.; Peterson, J. R.

2013-09-01

172

Investigation of device imperfection influence on measurement results in beamsplitter-based quantum random number generation schemes  

NASA Astrophysics Data System (ADS)

Quantum random number generation allows acquiring true random numbers which can be used in applications that require a high degree of randomness. This paper assesses the influence of non-ideal scheme parameters on measurement results in two quantum random number generation schemes: based on laser radiation splitting, and using vacuum fluctuations.

Ivanova, A. E.; Chivilikhin, S. A.; Egorov, V. I.; Gleim, A. V.

2014-10-01

173

Retrieval of temperature and concentration profiles from a limited number of absorption measurements  

NASA Astrophysics Data System (ADS)

The underlying reconstruction problems in the retrieval of temperature and concentration profiles from absorption measurements for spatially inhomogeneous flows were identified. Established methods for obtaining the inverse of the applicable integral equations, viz., Abel's equation for axisymmetric cases and the Radon transform for asymmetric ones, are not well-suited for limited data problems. For axisymmetric problems involving the Abel integral equations, a nonlinear inversion method bases on functional representation by cubic splines was developed with a view to minimize the number of measurements required. Factors affecting this number were studied, and the efficacy of the proposed inversion method was demonstrated using absorption data synthetically generated from typical experimentally observed temperature concentrated profiles. For the more general case on non-axisymmetric problems involving the Radon transform, two reconstruction methods that recognize smoothness to be a priori information and use numerically space-limited basis functions were developed. The first method is a modification of the well-known convolution backprojection method. The second method, termed the Finite Domain Direct Inversions, is a continuous ART that employs consistent basis functions for the projections as well as the distribution, and makes use in a rigorous way of their a priori information such as the constraint on the domain as well as the range of distribution.

Ravichandran, M.

1988-05-01

174

Characteristics of stratospheric turbulent layers measured by LITOS and their relation to the Richardson number  

NASA Astrophysics Data System (ADS)

Based on high-resolution turbulence measurements performed with the newly established balloon-borne instrument Leibniz Institute Turbulence Observations in the Stratosphere (LITOS) during the Balloon Experiments for University Students (BEXUS) 6 and BEXUS 8 campaigns from Kiruna, we derived characteristics of stratospheric turbulence layers, like their thickness and distance in between. Typically, the layers are ˜15-130 m thick and have a distance of ˜60-270 m, and their number increases with altitude. Due to the very high measurement resolution of LITOS in the range of millimeters, we obtain energy dissipation rate profiles with unprecedented precision. Within the turbulent layers we get a mean dissipation rate of 3.4×10-2W/kg (BEXUS 6) and 1.1 × 10-2 W/kg (BEXUS 8) corresponding to a heating rate of 1 to ˜3 K/d. The profiles show an increase of the energy dissipation with altitude. Comparisons with the Richardson number Ri preclude a clear correlation between the occurrence of turbulence and Ri<1/4. Despite the expected occurrence of turbulence at Ri<1/4, we also observed turbulent layers where Ri was >1/4 and far beyond, independent of the scale over which Ri has been determined.

Haack, A.; Gerding, M.; Lübken, F.-J.

2014-09-01

175

Measuring Cation Transport by Na,K- and H,K-ATPase in Xenopus Oocytes by Atomic Absorption Spectrophotometry: An Alternative to Radioisotope Assays  

PubMed Central

Whereas cation transport by the electrogenic membrane transporter Na+,K+-ATPase can be measured by electrophysiology, the electroneutrally operating gastric H+,K+-ATPase is more difficult to investigate. Many transport assays utilize radioisotopes to achieve a sufficient signal-to-noise ratio, however, the necessary security measures impose severe restrictions regarding human exposure or assay design. Furthermore, ion transport across cell membranes is critically influenced by the membrane potential, which is not straightforwardly controlled in cell culture or in proteoliposome preparations. Here, we make use of the outstanding sensitivity of atomic absorption spectrophotometry (AAS) towards trace amounts of chemical elements to measure Rb+ or Li+ transport by Na+,K+- or gastric H+,K+-ATPase in single cells. Using Xenopus oocytes as expression system, we determine the amount of Rb+ (Li+) transported into the cells by measuring samples of single-oocyte homogenates in an AAS device equipped with a transversely heated graphite atomizer (THGA) furnace, which is loaded from an autosampler. Since the background of unspecific Rb+ uptake into control oocytes or during application of ATPase-specific inhibitors is very small, it is possible to implement complex kinetic assay schemes involving a large number of experimental conditions simultaneously, or to compare the transport capacity and kinetics of site-specifically mutated transporters with high precision. Furthermore, since cation uptake is determined on single cells, the flux experiments can be carried out in combination with two-electrode voltage-clamping (TEVC) to achieve accurate control of the membrane potential and current. This allowed e.g. to quantitatively determine the 3Na+/2K+ transport stoichiometry of the Na+,K+-ATPase and enabled for the first time to investigate the voltage dependence of cation transport by the electroneutrally operating gastric H+,K+-ATPase. In principle, the assay is not limited to K+-transporting membrane proteins, but it may work equally well to address the activity of heavy or transition metal transporters, or uptake of chemical elements by endocytotic processes. PMID:23462593

Dürr, Katharina L.; Tavraz, Neslihan N.; Spiller, Susan; Friedrich, Thomas

2013-01-01

176

Measuring cation transport by Na,K- and H,K-ATPase in Xenopus oocytes by atomic absorption spectrophotometry: an alternative to radioisotope assays.  

PubMed

Whereas cation transport by the electrogenic membrane transporter Na(+),K(+)-ATPase can be measured by electrophysiology, the electroneutrally operating gastric H(+),K(+)-ATPase is more difficult to investigate. Many transport assays utilize radioisotopes to achieve a sufficient signal-to-noise ratio, however, the necessary security measures impose severe restrictions regarding human exposure or assay design. Furthermore, ion transport across cell membranes is critically influenced by the membrane potential, which is not straightforwardly controlled in cell culture or in proteoliposome preparations. Here, we make use of the outstanding sensitivity of atomic absorption spectrophotometry (AAS) towards trace amounts of chemical elements to measure Rb(+) or Li(+) transport by Na(+),K(+)- or gastric H(+),K(+)-ATPase in single cells. Using Xenopus oocytes as expression system, we determine the amount of Rb(+) (Li(+)) transported into the cells by measuring samples of single-oocyte homogenates in an AAS device equipped with a transversely heated graphite atomizer (THGA) furnace, which is loaded from an autosampler. Since the background of unspecific Rb(+) uptake into control oocytes or during application of ATPase-specific inhibitors is very small, it is possible to implement complex kinetic assay schemes involving a large number of experimental conditions simultaneously, or to compare the transport capacity and kinetics of site-specifically mutated transporters with high precision. Furthermore, since cation uptake is determined on single cells, the flux experiments can be carried out in combination with two-electrode voltage-clamping (TEVC) to achieve accurate control of the membrane potential and current. This allowed e.g. to quantitatively determine the 3Na(+)/2K(+) transport stoichiometry of the Na(+),K(+)-ATPase and enabled for the first time to investigate the voltage dependence of cation transport by the electroneutrally operating gastric H(+),K(+)-ATPase. In principle, the assay is not limited to K(+)-transporting membrane proteins, but it may work equally well to address the activity of heavy or transition metal transporters, or uptake of chemical elements by endocytotic processes. PMID:23462593

Dürr, Katharina L; Tavraz, Neslihan N; Spiller, Susan; Friedrich, Thomas

2013-01-01

177

In situ magnetotransport measurements in ultrathin Bi films: evidence for surface-bulk coherent transport.  

PubMed

We performed in situ magnetotransport measurements on ultrathin Bi(111) films [4-30 bilayers (BLs), 16-120 Å thick] to elucidate the role of bulk or surface states in the transport phenomena. We found that the temperature dependence of the film conductivity shows no thickness dependence for the 6-16 BL films and is affected by the electron-electron scattering, suggesting surface-state dominant contribution. In contrast, the weak antilocalization effect observed by applying a magnetic field shows clear thickness dependence, indicating bulk transport. This apparent inconsistency is explained by a coherent bulk-surface coupling that produces a single channel transport. For the films thicker than 20 BLs, the behavior changes drastically which can likely be interpreted as a bulk dominant conduction. PMID:25432051

Aitani, Masaki; Hirahara, Toru; Ichinokura, Satoru; Hanaduka, Masahiro; Shin, Dongyoon; Hasegawa, Shuji

2014-11-14

178

In situ Magnetotransport Measurements in Ultrathin Bi Films: Evidence for Surface-Bulk Coherent Transport  

NASA Astrophysics Data System (ADS)

We performed in situ magnetotransport measurements on ultrathin Bi(111) films [4-30 bilayers (BLs), 16-120 Å thick] to elucidate the role of bulk or surface states in the transport phenomena. We found that the temperature dependence of the film conductivity shows no thickness dependence for the 6-16 BL films and is affected by the electron-electron scattering, suggesting surface-state dominant contribution. In contrast, the weak antilocalization effect observed by applying a magnetic field shows clear thickness dependence, indicating bulk transport. This apparent inconsistency is explained by a coherent bulk-surface coupling that produces a single channel transport. For the films thicker than 20 BLs, the behavior changes drastically which can likely be interpreted as a bulk dominant conduction.

Aitani, Masaki; Hirahara, Toru; Ichinokura, Satoru; Hanaduka, Masahiro; Shin, Dongyoon; Hasegawa, Shuji

2014-11-01

179

Review of Skin Friction Measurements Including Recent High-Reynolds Number Results from NASA Langley NTF  

NASA Technical Reports Server (NTRS)

This paper reviews flat plate skin friction data from early correlations of drag on plates in water to measurements in the cryogenic environment of The NASA Langley National Transonic Facility (NTF) in late 1996. The flat plate (zero pressure gradient with negligible surface curvature) incompressible skin friction at high Reynolds numbers is emphasized in this paper, due to its importance in assessing the accuracy of measurements, and as being important to the aerodynamics of large scale vehicles. A correlation of zero pressure gradient skin friction data minimizing extraneous effects between tests is often used as the first step in the calculation of skin friction in complex flows. Early data compiled by Schoenherr for a range of momentum thickness Reynolds numbers, R(sub Theta) from 860 to 370,000 contained large scatter, but has proved surprisingly accurate in its correlated form. Subsequent measurements in wind tunnels under more carefully controlled conditions have provided inputs to this database, usually to a maximum R(sub Theta) of about 40,000. Data on a large axisymmetric model in the NASA Langley National Transonic Facility extends the upper limit in incompressible R(sub Theta) to 619,800 using the van Driest transformation. Previous data, test techniques, and error sources ar discussed, and the NTF data will be discussed in detail. The NTF Preston tube and Clauser inferred data accuracy is estimated to be within -2 percent of a power-law curve fit, and falls above the Spalding theory by 1 percent at R(sub Theta) of about 600,000.

Watson, Ralph D.; Hall, Robert M.; Anders, John B.

2000-01-01

180

Measurements Required to Understand the Lunar Dust Environment and Transport Mechanism  

NASA Technical Reports Server (NTRS)

Going back to the lunar surface offers an opportunity to understand the dust environment and associated transport mechanisms. This talk will explore what measurements are required to understand and characterize the dust-plasma environment in which robotic and human activities will be conducted. The understanding gained with the measurements can be used to make informed decisions on engineering solutions and follow-on investigations. Particular focus will be placed on required measurements of the size, spatial and charge distribution of the suspended lunar regolith.

Spann, James F., Jr.; Abbas, Mian

2006-01-01

181

Numerical Study of Flow Angles and Mach Number Measurement Using the Surface Pressure of a Supersonic Aircraft with Nose Cone  

NASA Astrophysics Data System (ADS)

Numerical simulation of the flow around an air data sensor (ADS), which measures flow angles and Mach numbers using surface pressures on a nose cone, was conducted in this study. Effects of the half-cone angle on the flow angle and Mach number measurements were investigated. Results show that a large half-cone angle achieves high sensitivity of flow angle measurements. Results further demonstrated that a small half-cone angle achieves high-sensitivity of Mach number measurements. To satisfy these conflicting requests, we proposed the use of bi-conic nose cones with two gradients. High sensitivity was achieved for both flow angle measurements and Mach number measurements using this bi-conic nose cone.

Fukiba, Katsuyoshi; Tsuboi, Nobuyuki; Kobayashi, Hiroaki

182

Numerical Study on Flow Angles and Mach Number Measurement Using the Surface Pressure of a Supersonic Aircraft with Nosecone  

NASA Astrophysics Data System (ADS)

Numerical simulation on the Air Data Sensor System (ADS), which measures the flow angles and Mach number using the surface pressures on a nose cone, was conducted in this study. The effect of the half cone angle on the flow angle and Mach number measurement was investigated. As a result, we found that a large half cone angle achieves a high sensitivity at the flow angle measurement. It was also found that a small half cone angle achieves a high sensitivity at the Mach number measurement. To satisfy these conflicting requests, we proposed a new shape nose cone which has two different gradients. The high sensitivity was achieved at both the flow angle measurement and Mach number measurement by this new shape nose cone.

??, ??; ??, ??; ??, ??

183

Carrier mobility in organic charge transport materials: Methods of measurement, analysis, and modulation  

NASA Astrophysics Data System (ADS)

The measurement and control of charge carrier mobility in organic semiconductors are two prevalent issues in the growing field of organic electronics. The mobility is a measure of the speed of net charge movement per unit of applied field. This quantity determines how fast circuits and elements can respond and how much current they can support at a given voltage. While there are many methods to measure the hole and electron mobilities of organic materials, each has its own limitations and requirements. There is room for new methods to allow the measurement of additional materials and in different circumstances. In addition, exploring the capability of molecular systems to modulate these mobilities provides opportunities for improvements in the performance of organic electronic devices. This thesis has focused on developing new methods of measuring the charge carrier mobility in organic semiconductors and on evaluating the capability of a series of hybrid compounds to modulate the emitting layer's mobilities for application in organic light-emitting diodes. Key results are summarized as follows: (1) The charge-retraction time-of-flight technique for carrier mobility measurements was explained, explored, and validated with two well know hole transport materials producing retraction transients nearly identical to those of photocurrent time-of-flight, while amenable to thinner samples and utilizing a simple, all-electrical experimental setup. In addition, a method to determine the transition voltage more accurately in these devices was developed. (2) The electron mobilities of a known electron transport material and an unknown polycrystalline electron transport material were measured by both charge-retraction time-of-flight and photocurrent time-of-flight. The results for the known compound were found to match within error for both techniques, and various measures of how dispersive the transport was also matched very closely, validating the charge-retraction time-of-flight technique for dispersive and electron transport. (3) The integrating-mode photocurrent time-of-flight technique was described in detail, and an analysis method extending Scher and Montroll's procedures to integrating-mode transients was derived and explored. The mobility values determined by this analysis, as well as three other methods (two of them from the literature) were compared and contrasted for nondispersive hole transport and dispersive electron transport, and the analysis developed here was found to be the only one to agree with traditional, current-mode time-of-flight for both cases. (4) Three compounds were synthesized to complete a series of hybrid materials designed to modulate the carrier mobilities in the emitter layer of organic light-emitting diodes. The hole and electron mobilities of these compounds were measured by photocurrent time-of-flight, in both current- and integrating-modes, as functions of field and temperature. It was found that the mobilities in these compounds spanned over four orders of magnitude, with the ratios of the hole to the electron mobility in neat layers ranging from 59:1 to 1:180. The trends in these mobilities were discussed using the disorder formalism for charge transport.

Wallace, Jason U.

184

A rigorous bound on the vertical transport of heat in Rayleigh-Bénard convection at infinite Prandtl number with mixed thermal boundary conditions  

NASA Astrophysics Data System (ADS)

A rigorous upper bound on the Nusselt number is derived for infinite Prandtl number Rayleigh-Bénard convection for a fluid constrained between no-slip, mixed thermal vertical boundaries. The result suggests that the thermal boundary condition does not affect the qualitative nature of the heat transport. The bound is obtained with the use of a nonlinear, stably stratified background temperature profile in the bulk, notwithstanding the lack of boundary control of the temperature due to the Robin boundary conditions.

Whitehead, Jared P.; Wittenberg, Ralf W.

2014-09-01

185

Detailed Measurements of Turbulent Rayleigh-Taylor Mixing at Large and Small Atwood Numbers  

SciTech Connect

This project has two major tasks: Task 1. The construction of a new air/helium facility to collect detailed measurements of Rayleigh-Taylor (RT) mixing at high Atwood number, and the distribution of these data to LLNL, LANL, and Alliance members for code validation and design purposes. Task 2. The collection of initial condition data from the new Air/Helium facility, for use with validation of RT simulation codes at LLNL and LANL. Also, studies of multi-layer mixing with the existing water channel facility. Over the last twelve (12) months there has been excellent progress, detailed in this report, with both tasks. As of December 10, 2004, the air/helium facility is now complete and extensive testing and validation of diagnostics has been performed. Currently experiments with air/helium up to Atwood numbers of 0.25 (the maximum is 0.75, but the highest Reynolds numbers are at 0.25) are being performed. The progress matches the project plan, as does the budget, and we expect this to continue for 2005. With interest expressed from LLNL we have continued with initial condition studies using the water channel. This work has also progressed well, with one of the graduate Research Assistants (Mr. Nick Mueschke) visiting LLNL the past two summers to work with Dr. O. Schilling. Several journal papers are in preparation that describe the work. Two MSc.'s have been completed (Mr. Nick Mueschke, and Mr. Wayne Kraft, 12/1/03). Nick and Wayne are both pursuing Ph.D.s' funded by this DOE Alliances project. Presently three (3) Ph.D. graduate Research Assistants are supported on the project, and two (2) undergraduate Research Assistants. During the year two (2) journal papers and two (2) conference papers have been published, ten (10) presentations made at conferences, and three (3) invited presentations.

Malcolm J. Andrews, Ph.D.

2004-12-14

186

Number of first-passage times as a measurement of information for weakly chaotic systems  

E-print Network

We consider a general class of maps of the interval having Lyapunov subexponential instability $|\\delta x_{t}|\\sim|\\delta x_{0}|\\exp[\\Lambda_{t}(x_{0})\\zeta(t)]$, where $\\zeta(t)$ grows sublinearly as $t\\rightarrow\\infty$. We outline here a scheme [J. Stat. Phys. {\\bf 154}, 988 (2014)] whereby the choice of a characteristic function automatically defines the map equation and corresponding growth rate $\\zeta(t)$. This matching approach is based on the infinite measure property of such systems. We show that the average information that is necessary to record without ambiguity a trajectory of the system tends to $\\langle\\Lambda\\rangle\\zeta(t)$, suitably extending the Kolmogorov-Sinai entropy and Pesin's identity. For such systems, information behaves like a random variable for random initial conditions, its statistics obeying a universal Mittag-Leffler law. We show that, for individual trajectories, information can be accurately inferred by the number of first-passage times through a given turbulent phase space cell. This enables us to calculate far more efficiently Lyapunov exponents for such systems. Lastly, we also show that the usual renewal description of jumps to the turbulent cell, usually employed in the literature, does not provide the real number of entrances there. Our results are supported by exhaustive numerical simulations.

Pierre Nazé; Roberto Venegeroles

2014-03-31

187

Externally driven global Alfvén eigenmodes applied for effective mass number measurement on TCABR  

NASA Astrophysics Data System (ADS)

The excitation and detection of Global Alfvén Eigenmodes on TCABR for diagnostic purposes are presented. The modes can be excited with one or two in-vessel antennae, with up to 15 A of current in each, in the frequency range from 2 to 4 MHz. This scheme allows the estimation of the effective mass number at the plasma center, which value is affected by impurity concentration in the core. An amplifier based on MOSFETs is used to excite the waves driven by low power, in order to not change the basic plasma parameters. The variation of the GAE with density is verified and the location of the mode resonance at the plasma center is confirmed by the sawtooth beating, so that the correspondingly beating phase inversion improves the precision on the resonant condition determination. The toroidal parity of the modes N = 1,2 is determined by use of two opposite located antennae with different phase of the RF current. Knowledge of toroidal mode number is important as it identifies GAE location and defines the estimated effective mass value. The estimated value for Aeff is ˜1.4-1.5, corresponding to 5-7% of carbon impurity concentration. The measured value of Aeff is used to estimate Zeff, which is compared to older TCA experiments and the value obtained by the Spitzer conductivity.

Puglia, P. G. P. P.; Elfimov, A. G.; Ruchko, L. F.; Galvão, R. M. O.; Guimarães-Filho, Z.; Ronchi, G.

2014-12-01

188

FRET measurements between small numbers of molecules identifies subtle changes in receptor interactions  

NASA Astrophysics Data System (ADS)

Overexpression of HER2 alters the cellular behavior of EGF receptor (EGFR) and itself, with great implications on cell fate. To understand the molecular interactions underlying these alterations, we quantified the association between the two receptors by looking at efficiency changes in fluorescence resonance energy transfer (FRET) between a small number of molecules at the membrane of living cells. Human mammary epithelial (HME) cells expressing varying degrees of HER2 were studied, to identify and compare the degree of receptors interactions as a function of HER2 overexpression. A high resolution wide-field laser microscope combined with a high sensitivity cooled CCD camera was used to capture simultaneously donor and acceptor emissions. Alternating between green and red lasers every 80 msec, donor, FRET, and acceptor images were acquired and were used to calculate FRET efficiency. Automated image analysis was developed to create FRET efficiency maps from overlapping donor, acceptor and FRET images, and derive FRET efficiency histograms to quantify receptor-receptor interactions pixel by pixel. This approach enabled us to detect subtle changes in the average distance between EGFR molecules, and between EGFR and HER2. We found pre-existing EGFR homoassociations, and EGFR-HER2 heteroassociations in cells overexpressing HER2, and identified the changes in these interactions with ligand stimulation. These observations demonstrate the power of FRET measurements between small numbers of molecules in identifying subtle changes in molecular interactions in living cell.

Ozcelik, Serdar; Orr, Galya; Hu, Dehong; Chen, Chii-Shiarng; Resat, Haluk; Harms, Greg S.; Opresko, Lee K.; Wiley, H. Steven; Colson, Steven D.

2004-06-01

189

Measurements of mass attenuation coefficient, effective atomic number and electron density of some amino acids  

NASA Astrophysics Data System (ADS)

The mass attenuation coefficients of some amino acids, such as DL-aspartic acid-LR(C4H7NO4), L-glutamine (C4H10N2O3), creatine monohydrate LR(C4H9N3O2H2O), creatinine hydrochloride (C4H7N3O·HCl) L-asparagine monohydrate(C4H9N3O2H2O), L-methionine LR(C5H11NO2S), were measured at 122, 356, 511, 662, 1170, 1275 and 1330 keV photon energies using a well-collimated narrow beam good geometry set-up. The gamma-rays were detected using NaI (Tl) scintillation detection system with a resolution of 0.101785 at 662 keV. The attenuation coefficient data were then used to obtain the effective atomic numbers (Zeff), and effective electron densities (Neff) of amino acids. It was observed that the effective atomic number (Zeff) and effective electron densities (Neff) initially decrease and tend to be almost constant as a function of gamma-ray energy. Zeff and Neff experimental values showed good agreement with the theoretical values with less than 1% error for amino acids.

Kore, Prashant S.; Pawar, Pravina P.

2014-05-01

190

Theoretical and measured aeolian sand transport on a barrier island, Louisiana, USA  

USGS Publications Warehouse

Over the past 100 yr, the Isles Dernieres, a low lying barrier island chain along the coast of central Louisiana, has undergone more than 1km of northward beach face retreat within the loss of 70% of its surface area. The erosion results from a long term relative sea level rise coupled with day to day wind and wave action that ultimately favours erosion over deposition. The theoretical estimate of 1.28 m3 m-1 for the rate of sand transport by the northerly wind compares well with the measured backshore erosion rate of 1.26m3 m-1, which was determined by comparing beach profiles from the start and end of the period of northerly winds. The theoretical estimate of 0.04m3 m-1 for the rate of sand transport by the southerly wind, however, is notably less than the measured rate of 0.45m3 m-1. -from Authors

Dingler, J.R.; Hsu, S.A.; Reiss, T.E.

1992-01-01

191

Analysis of long-range transport of aerosols for Portugal using 3D chemical transport model and satellite measurements  

NASA Astrophysics Data System (ADS)

The objective of this work is to assess the contribution of long-range transport of mineral dust from North Africa to the air pollution levels in Portugal based on a combination of a modelling approach and satellite observations. The Comprehensive Air Quality Model (CAMx) was applied together with the updated Dust REgional Atmospheric Model (BSC-DREAM8b) to characterise anthropogenic and natural sources of primary aerosols as well as secondary aerosols formation. The modelling results, after their validation and bias removing process, have been used in combination with aerosol measurements provided by Ozone Monitoring Instrument (OMI), using OMAERUV Level-2 v003 product, aiming to better understand the advantages and shortcomings of both, satellite and modelling aerosol data. The data analysis is presented for Portugal for July 2006 focusing on aerosol optical depth (AOD) at 500 nm and aerosol type. Based on the modelling results, the importance of the long-range transport of mineral dust was demonstrated for the simulation days, achieving a 60% contribution to AOD levels. The mineral dust is affecting atmospheric layers up to 6 km but peak concentrations are presented at layers below 2 km. The model predicts a complex mixture of different types of aerosol for the pixels classified by OMI as "mineral dust" and "sulphates". Although a good agreement between the model outputs and OMI observations has been found in terms of the spatial pattern and AOD correlation is about 0.48 for mineral dust, several problems were identified. The model is systematically underestimating the aerosol concentration at near ground level in comparison with the air quality monitoring stations, while OMI is in general overestimating AOD for the analysed period based on the comparison with AERONET data. Additionally, misclassification of mineral dust for some geographical locations and discontinuity in AOD values along the coastal line at water/land interface in the OMI data are discussed.

Tchepel, O.; Ferreira, J.; Fernandes, A. P.; Basart, S.; Baldasano, J. M.; Borrego, C.

2013-01-01

192

Measurement of urban traffic noise due to heavy cargo transport services  

NASA Astrophysics Data System (ADS)

The Acoustic and Electroacoustic Laboratory of the Buenos Aires University is working on a Traffic Noise Recommendation to be used in Argentina. To that end, measurements of traffic noise due to heavy cargo transport services were taken in a Buenos Aires neighbourhood, especially asked for by a neighborhood association. The goal of this measurement was to try to define a correct standard set for the annoyance level in order to pass that information to the city government and work together to improve the living standard of the inhabitants. The measured indexes were Leq, L90 and L10, as well as octave measurement focused on frequencies under 250 Hz. This paper will show the results of the measurements and the conclusions that were made.

Ruffa, Francisco; Gavinowich, Daniel S.; Barkasz, Erica A.; Ciccarella, Pablo R.

2002-11-01

193

Measurement of water transport from saturated pumice aggregates to hardening cement paste  

Microsoft Academic Search

In internal water curing of High Performance Concrete, it is fundamental to know how and when the water contained in the internal\\u000a curing agent is released into the hydrating cement paste. In this study, X-ray absorption measurements showed that considerable\\u000a transport of water from saturated pumice stone to hydrating cement paste with water\\/cement ratio 0.3 took place in the first

Pietro Lura; Dale P. Bentz; David A. Lange; Konstantin Kovler; Arnon Bentur; Klaas van Breugel

2006-01-01

194

Electric transport properties of Mn12-acetate films measured with self-assembling tunnelling junction  

Microsoft Academic Search

Electric transport properties of Mn12-acetate films have been measured with a self-assembling tunnelling junction device at a liquid helium temperature of 4.2 K. For fresh films, clean I-V characteristics including the zero bias feature and the stair-case like I-V curves are observed. For stored films, however, all those features disappear and 'telegraph' noise appears, which indicate the deterioration of the

Lianxi Ma; Chi Chen; Glenn Agnolet; Jiacai Nie; Hanhua Zhao; Kim R. Dunbar

2009-01-01

195

Turbulence Measurements of a High Reynolds Number Inclined Jet in Crossflow using PIV and FRAP  

NASA Astrophysics Data System (ADS)

The TKE, turbulence intensity and Reynolds shear stress for a jet inclined at 30^o to the freestream with a blowing ratio of 2 and Reynolds numbers, based on hole diameter, (Red) of 30000 are measured using 3-D Stereoscopic PIV and a miniature Fast Response Aerodynamic Probe (FRAP). The Maximum Entropy Method is used to compose a spectrum for variance calculations from PIV data, thereby ameliorating the low sampling rate and systematic noise. The PIV measurements are compared with those from the FRAP and found to be within error estimates. TKE contours indicate that the two main sites of turbulence production are the counter rotating vortex pair and the shearing surface of the jet. It is observed that the turbulence within the vortex pair is higher and dissipates slower than that in the jet shear surface. The eddy diffusivities of momentum in different cardinal directions are also compared and found to have an anistropic distribution. The mechanisms of turbulent mixing in this complex flow and their relevance to turbulence modeling are commented upon.

Aga, Vipluv; Feliciani, Claudio; Chokani, Ndaona; Abhari, Reza

2007-11-01

196

Turbulent wall pressure fluctuation measurements on a towed model at high Reynolds numbers  

NASA Astrophysics Data System (ADS)

Turbulent wall pressure fluctuation measurements were made in water on a towed model of length 129.8 (m) and diameter 3.8 (cm) for steady speeds from 6.2 (m/s) to 15.5 (m/s). The drag on the model was measured with a strut mounted load cell which provided estimates of the momentum thickness and friction velocity. Momentum thickness Reynolds numbers Re ? varied from 4.8 × 105 to 1.1 × 106. The ratio of momentum thickness to viscous length scale is significantly greater than for flat plate cases at comparable Re ?. The effectiveness of inner and outer velocity and length scales for collapsing the pressure spectra are discussed. The wavenumber-frequency spectra show a convective ridge at higher frequencies similar to flat plate boundary layers. At low frequencies, energy broad in wavenumber extends outside the convective ridge and acoustic cone, with no characteristic wave speed. Wall pressure cross-spectral levels scaled with similarity variables are shown to increase with increasing tow speed, and to follow decay constants consistent with flat plate cases. The convection velocities also display features similar to flat plate cases.

Keith, William L.; Cipolla, Kimberly M.; Furey, Deborah

2009-01-01

197

Multi-energy soft-x-ray technique for impurity transport measurements in the fusion plasma edge  

NASA Astrophysics Data System (ADS)

A new diagnostic technique was developed to produce high-resolution impurity transport measurements of the steep-gradient edge of fusion plasmas. Perturbative impurity transport measurements were performed for the first time in the NSTX plasma edge (r/a ˜ 0.6 to the SOL) with short neon gas puffs, and the resulting line and continuum emission was measured with the new edge multi-energy soft-x-ray (ME-SXR) diagnostic. Neon transport is modeled with the radial impurity transport code STRAHL and the resulting x-ray emission is computed using the ADAS atomic database. The radial transport coefficient profiles D(r) and v(r), and the particle flux from the gas puff ?(t), are the free parameters in this model and are varied to find the best fit to experimental x-ray emissivity measurements, with bolometry used to constrain the impurity source. Initial experiments were successful and results were consistent with previous measurements of core impurity transport and neoclassical transport calculations. New diagnostic tools will be implemented on NSTX-U to further improve these transport measurements.

Clayton, D. J.; Tritz, K.; Stutman, D.; Finkenthal, M.; Kaye, S. M.; Kumar, D.; LeBlanc, B. P.; Paul, S.; Sabbagh, S. A.

2012-10-01

198

Measurement of Black Carbon and Particle Number Emission Factors from Individual Heavy-Duty Trucks  

SciTech Connect

Emission factors for black carbon (BC) and particle number (PN) were measured from 226 individual heavy-duty (HD) diesel-fueled trucks driving through a 1 km-long California highway tunnel in August 2006. Emission factors were based on concurrent increases in BC, PN, and CO{sub 2}B concentrations (measured at 1 Hz) that corresponded to the passage of individual HD trucks. The distributions of BC and PN emission factors from individual HD trucks are skewed, meaning that a large fraction of pollution comes from a small fraction of the in-use vehicle fleet. The highest-emitting 10% of trucks were responsible for {approx} 40% of total BC and PN emissions from all HD trucks. BC emissions were log-normally distributed with a mean emission factor of 1.7 g kg {sup -1} and maximum values of {approx} 10 g kg{sup -1}. Corresponding values for PN emission factors were 4.7 x 10{sup 15} and 4 x 10{sup 16} kg{sup -1}. There was minimal overlap among high-emitters of these two pollutants: only 1 of the 226 HD trucks measured was found to be among the highest 10% for both BC and PN. Monte Carlo resampling of the distribution of BC emission factors observed in this study revealed that uncertainties (1{sigma}) in extrapolating from a random sample of n HD trucks to a population mean emission factor ranged from {+-} 43% for n = 10 to {+-} 8% for n = 300, illustrating the importance of sufficiently large vehicle sample sizes in emissions studies. Studies with low sample sizes are also more easily biased due to misrepresentation of high-emitters. As vehicles become cleaner on average in future years, skewness of the emissions distributions will increase, and thus sample sizes needed to extrapolate reliably from a subset of vehicles to the entire in-use vehicle fleet are expected to become more of a challenge.

Ban-Weiss, George A.; Lunden, Melissa M.; Kirchstetter, Thomas W.; Harley, Robert A.

2009-02-02

199

Method and apparatus for measuring coupled flow, transport, and reaction processes under liquid unsaturated flow conditions  

DOEpatents

The present invention is a method and apparatus for measuring coupled flow, transport and reaction processes under liquid unsaturated flow conditions. The method and apparatus of the present invention permit distinguishing individual precipitation events and their effect on dissolution behavior isolated to the specific event. The present invention is especially useful for dynamically measuring hydraulic parameters when a chemical reaction occurs between a particulate material and either liquid or gas (e.g. air) or both, causing precipitation that changes the pore structure of the test material.

McGrail, Bernard P. (Pasco, WA); Martin, Paul F. (Richland, WA); Lindenmeier, Clark W. (Richland, WA)

1999-01-01

200

A transverse emittance and acceptance measurement system in a low-energy beam transport line.  

PubMed

A transverse beam emittance and acceptance measurement system has been developed to visualize the relationship between the injected beam emittance and the acceptance of a cyclotron. The system is composed of a steering magnet, two pairs of slits to limit the horizontal and vertical phase-space, a beam intensity detector just behind the slits for the emittance measurement, and a beam intensity detector in the cyclotron for the acceptance measurement. The emittance is obtained by scanning the slits and measuring the beam intensity distribution. The acceptance is obtained by measuring the distribution of relative beam transmission by injecting small emittance beams at various positions in a transverse phase-space using the slits. In the acceptance measurement, the beam from an ion source is deflected to the defined region by the slits using the steering magnet so that measurable acceptance area covers a region outside the injection beam emittance. Measurement tests were carried out under the condition of accelerating a beam of (16)O(6+) from 50.2 keV to 160 MeV. The emittance of the injected beam and the acceptance for accelerating and transporting the beam to the entrance of the extraction deflector were successfully measured. The relationship between the emittance and acceptance is visualized by displaying the results in the same phase-plane. PMID:24593469

Kashiwagi, H; Miyawaki, N; Kurashima, S; Okumura, S

2014-02-01

201

A transverse emittance and acceptance measurement system in a low-energy beam transport line  

SciTech Connect

A transverse beam emittance and acceptance measurement system has been developed to visualize the relationship between the injected beam emittance and the acceptance of a cyclotron. The system is composed of a steering magnet, two pairs of slits to limit the horizontal and vertical phase-space, a beam intensity detector just behind the slits for the emittance measurement, and a beam intensity detector in the cyclotron for the acceptance measurement. The emittance is obtained by scanning the slits and measuring the beam intensity distribution. The acceptance is obtained by measuring the distribution of relative beam transmission by injecting small emittance beams at various positions in a transverse phase-space using the slits. In the acceptance measurement, the beam from an ion source is deflected to the defined region by the slits using the steering magnet so that measurable acceptance area covers a region outside the injection beam emittance. Measurement tests were carried out under the condition of accelerating a beam of {sup 16}O{sup 6+} from 50.2 keV to 160 MeV. The emittance of the injected beam and the acceptance for accelerating and transporting the beam to the entrance of the extraction deflector were successfully measured. The relationship between the emittance and acceptance is visualized by displaying the results in the same phase-plane.

Kashiwagi, H., E-mail: kashiwagi.hirotsugu@jaea.go.jp; Miyawaki, N.; Kurashima, S.; Okumura, S. [Department of Advanced Radiation Technology, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)] [Department of Advanced Radiation Technology, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)

2014-02-15

202

Transportation  

NSDL National Science Digital Library

A unit designed to increase students' knowledge and understanding of diesel and gasoline engines, providing an introduction for students interested in more specialized training in the automobile field and its scientific principles through math, science, and chemistry. It will also help students realize the importance of transportation, and will help them meet their needs in math through problem solving by dealing with materials in their world, letting them develop skills and techniques through hands-on experience. Includes more than 20 problems to solve.

Bryant, Joyce

2007-05-12

203

Neutron spectra and dose-rate measurements around a transport cask for spent reactor fuel  

NASA Astrophysics Data System (ADS)

A storage facility with a capacity of 420 containers is available for the interim storage of spent fuel from power reactors at the village of Gorleben in Germany. During transportation and storage of spent fuel casks radiation exposure of the personnel is dominated by neutrons. The routine control of the dose rate limits according to the transport regulations and the licence of the storage facility is performed with conventional neutron survey meters. These monitors, calibrated for fast neutrons at radionuclide neutron sources, usually overestimate the real dose rate in unknown neutron fields. In this paper, a series of measurements with several monitoring instruments near a transport cask of the CASTOR type is presented. The results are compared with reference data for the does equivalents calculated from the measured fluence spectra using a Bonner multisphere spectrometer. Besides reliable information about neutron spectra and dose rates at the container, it was found that some of the rem counters overestimate the true dose rate by a factor of 2 or more.

Rimpler, Arndt

1997-02-01

204

Comparison of energy transport measurements and computer simulations in a single module prototype for PBFA II  

SciTech Connect

The 36-module Particle Beam Fusion Accelerator (PBFA II) is designed to provide a 30 MV pulse, with greater than 150 TW, to a centrally located lithium ion diode. Each module is driven by a 6 MV, 400 kJ Marx generator and uses three water-insulated and switched pulse compression stages followed by a voltage inversion-adder unit. All impedance matching transmission-line transformer couples the output pulse from the inversion-adder unit to the central vacuum insulator, plasma erosion switches, and ion diode. The prototype of a single PBFA-II module, called Demon, is being used to test component design, including a mock-up of a section of the vacuum insulator, and to determine overall module operatting characteristics. This paper presents the results of measurements of energy transport efficiencies through the successive pulse compression stages. Results of energy transport measurements on an 18 module, one-fifth scale model, are also compared to the single-line data. We present a comparison of measured parameters with computer circuit code simulations of the hardware design. Comparisons are used to suggest areas of possible improvements. The measured module output characteristics agree with the code simulations and meet the design requirements for the PBFA-II accelerator.

Neau, E.L.; Seamen, J.F.; Bloomquist, D.D.; Babcock, S.R.; Schneider, L.X.; Sujka, B.R.

1985-01-01

205

Radicals and Reservoirs in the GMI Chemistry and Transport Model: Comparison to Measurements  

NASA Technical Reports Server (NTRS)

We have used a three-dimensional chemistry and transport model (CTM), developed under the Global Modeling Initiative (GMI), to carry out two simulations of the composition of the stratosphere under changing halogen loading for 1995 through 2030. The two simulations differ only in that one uses meteorological fields from a general circulation model while the other uses meteorological fields from a data assimilation system. A single year's winds and temperatures are repeated for each 36-year simulation. We compare results from these two simulations with an extensive collection of data from satellite and ground-based measurements for 1993-2000. Comparisons of simulated fields with observations of radical and reservoir species for some of the major ozone-destroying compounds are of similar quality for both simulations. Differences in the upper stratosphere, caused by transport of total reactive nitrogen and methane, impact the balance among the ozone loss processes and the sensitivity of the two simulations to the change in composition.

Douglass, Anne R.; Stolarski, Richard S.; Strahan, Susan E.; Connell, Peter S.

2004-01-01

206

Airborne lidar measurements of pollution transport in central and southern California during CalNEX 2010  

NASA Astrophysics Data System (ADS)

During the CalNEX experiment from May through July 2010, we co-deployed NOAA’s airborne ozone and aerosol lidar TOPAZ and the University of Leeds scanning Doppler wind lidar on a Twin Otter aircraft. We flew a total of 46 missions over central and southern California, focusing primarily on the Los Angeles Basin and Sacramento areas. The downward-looking lidars provided highly resolved measurements of ozone concentration, aerosol backscatter, and wind speed and direction in the boundary layer and lower free troposphere. We will use the airborne lidar data to characterize transport of ozone and aerosols on regional and local scales. In particular, we will focus on pollutant transport between air basins and the role of flow patterns in complex terrain, such as gap flows and orographic lifting and venting along mountain slopes, on pollutant distribution.

Senff, C. J.; Alvarez, R. J., II; Hardesty, R.; Langford, A. O.; Banta, R. M.; Brewer, A.; Davies, F.; Sandberg, S.; Marchbanks, R.; Weickmann, A.

2010-12-01

207

Fast electron temperature, MHD and transport measurements on NSTX using a multi-energy SXR array  

NASA Astrophysics Data System (ADS)

A compact multi-energy soft X-ray array has been developed for fast (<=0.1 ms) time and space-resolved electron temperature, MHD and transport measurements on the National Spherical Torus Experiment (NSTX). The electron temperature is obtained by modeling the slope of the continuum radiation from ratios of the Abel inverted radial emissivity profiles in three energy ranges [1]. The applicability of this diagnostic technique to radio frequency electron heating and current drive experiments, perturbative electron and impurity transport studies, as well as an analysis of the impact of several types of MHD activity such as NTMs, RWMs, ELMs and Fishbones will be discussed. This work supported by U.S. DoE Contract No. DE-AC02-76CH03073 DoE and grant No. DE-FG02-99ER5452 at The Johns Hopkins University. [1] L. F. Delgado-Aparicio, et al., Plasma Phys. Controlled Fusion, 49, 1245 (2007).

Delgado-Aparicio, L. F.; Stutman, D.; Tritz, K.; Finkenthal, M.; Bell, R.; Hosea, J.; Kaye, S.; Leblanc, B.; Sabbagh, S.

2007-11-01

208

Indoor and outdoor measurements of particle number concentration in near-highway homes.  

PubMed

Exposure to high levels of traffic-generated particles may pose risks to human health; however, limited measurement has been conducted at homes near highways. The purpose of this study was to characterize differences between indoor and outdoor particle number concentration (PNC) in homes near to and distant from a highway and to identify factors that may affect infiltration. We monitored indoor and outdoor PNC (6-3000 nm) for 1-3 weeks at 18 homes located <1500 m from Interstate-93 (I-93) in Somerville, MA (USA). Median hourly indoor and outdoor PNC pooled over all homes were 5.2 × 10(3) and 5.9 × 10(3) particles/cm(3), respectively; the median ratio of indoor-to-outdoor PNC was 0.95 (5(th)/95th percentile: 0.42/1.75). Homes <100 m from I-93 (n=4) had higher indoor and outdoor PNC compared with homes >1000 m away (n=3). In regression models, a 10% increase in outdoor PNC was associated with an approximately equal (10.8%) increase in indoor PNC. Wind speed and direction, temperature, time of day and weekday were also associated with indoor PNC. Average mean indoor PNC was lower for homes with air conditioners compared with homes without air conditioning. These results may have significance for estimating indoor, personal exposures to traffic-related air pollution. PMID:23321863

Fuller, Christina H; Brugge, Doug; Williams, Paige L; Mittleman, Murray A; Lane, Kevin; Durant, John L; Spengler, John D

2013-01-01

209

Measurement and analysis of the noise radiated by low Mach numbers centrifugal blowers  

NASA Astrophysics Data System (ADS)

The broad band, aerodynamically generated noise in low tip-speed Mach number, centrifugal air moving devices is investigated. An interdisciplinary approach was taken which involved investigation of the aerodynamic and acoustic fields, and their mutual relationship. The noise generation process was studied using two experimental vehicles: (1) a scale model of a homologous family of centrifugal blowers typical of those used to cool computer and business equipment, and (2) a single blade from a centrifugal blower impeller which was placed in a known, controllable flow field. The radiation characteristics of the model blower were investigated by measuring the acoustic intensity distribution near the blower inlet and comparing it with the intensity near the inlet to an axial flow fan. Aerodynamic studies of the flow field in the inlet and at the discharge to the rotating impeller were used to assess the mean flow distribution through the impeller blade channels and to identify regions of excessive turbulence near the rotating blade row. New frequency-domain expressions for the correlation area and dipole source strength per unit area on a surface immersed in turbulence were developed which can be used to characterize the noise generation process over a rigid surface immersed in turbulence. An investigation of the noise radiated from the single, isolated airfoil (impeller blade) was performed using modern correlation and spectral analysis techniques.

Yeager, D. M.; Lauchle, G. C.

1987-11-01

210

A Validation of Eye Movements as a Measure of Elementary School Children's Developing Number Sense  

ERIC Educational Resources Information Center

The number line estimation task captures central aspects of children's developing number sense, that is, their intuitions for numbers and their interrelations. Previous research used children's answer patterns and verbal reports as evidence of how they solve this task. In the present study we investigated to what extent eye movements recorded…

Schneider, Michael; Heine, Angela; Thaler, Verena; Torbeyns, Joke; De Smedt, Bert; Verschaffel, Lieven; Jacobs, Arthur M.; Stern, Elsbeth

2008-01-01

211

Photocharge transport and recombination measurements in amorphous silicon films and solar cells by photoconductive frequency mixing: Annual subcontract report, 20 April 1998--19 April 1999  

SciTech Connect

In the present phase of the program, the transport parameters of a number of amorphous semiconductors prepared by a number of techniques were determined by the photoconductive frequency mixing technique. This technique enabled the authors to determine the drift mobility, md, and the photomixing lifetime, t. The technique is based on the idea of heterodyne detection for photoconductors. When two similarly polarized monochromatic optical beams of slightly different frequencies are incident upon a photoconductor, the generation rate of electron-hole pairs will produce a photocurrent, when a dc-bias is applied, which will contain components resulting from the square of the sum of the individual incident fields. Consequently, a photocurrent will be produced, which will consist of a direct current and a microwave current corresponding to the beat frequency. These two currents allow a separate determination of the drift mobility and the photomixing lifetime of the photogenerated carriers. In the present work, the longitudinal modes of a He-Ne laser were employed to generate a beat frequency of 252 MHz; all the measurements were performed at this frequency for the data indicated in the accompanying figures. The following topics were explored: Measurements of the charge transport parameters of homogeneous a-SiGe:H alloys produced by NREL employing the hot-wire technique; The change in the charge transport parameters in the transition from hydrogenated amorphous silicon to microcrystalline silicon for material produced by NREL and MVSystems; The improvement in instrumentation of the photomixing measurements; Measurements of the hydrostatic dependency of the transport parameters of amorphous silicon; and Preliminary photomixing measurements on p-i-n devices.

Braunstein, R.; Kattwinkel, A.; Liebe, J.; Sun, G.

2000-02-28

212

Gas Transport Parameters for Landfill Final Cover Soil: Measurements and Model Modification by Dry Bulk Density  

NASA Astrophysics Data System (ADS)

Landfill sites have been emerging in greenhouse warming scenarios as a significant source of atmospheric methane (CH4). Until recently, landfill management strategies have mainly addressed the problem of preventing groundwater contamination and reduction of leachate generation. Being one of the largest sources of anthropogenic CH4 emission, the final cover system should also be designed for minimizing the greenhouse gases migration into the atmosphere or the areas surrounding the landfill while securing the hydraulic performance. Compared to the intensive research efforts on hydraulic performances of landfill final cover soil, few studies about gas transport characteristics of landfill cover soils have been done. However, recent soil-gas studies implied that the effects of soil physical properties such as bulk density (i.e., compaction level), soil particle size are key parameters to understand landfill gaseous performance. The gas exchange through the final cover soils is controlled by advective and diffusive gas transport. Air permeability (ka) governs the advective gas transport while the soil-gas diffusion coefficient (Dp) governs diffusive gas transport. In this study, the effects of compaction level and particle size fraction effects on ka and Dp for landfill final cover soil was investigated. The disturbed soil samples were taken from landfill final cover in Japan. A compaction tests were performed for the soil samples with two different size fractions (< 35 mm and < 2.0 mm). In the compaction tests at field water content , the soil samples were repacked into soil cores (i.d. 15-cm, length 12-cm, 2120 cm3) at two different compaction levels [(MP):2700 kN/m2 and (SP):600 kN/m2]. After the compaction tests, ka and Dp were measured and then samples were saturated and subsequently drained at different soil-water matric potential of 0.98, 2.94, 9.81, 1235 kPa and with air-dried and oven-dried conditions. Results showed that measured Dp and ka values for the coarser (< 35 mm) fraction became larger than finer (< 2 mm) for the given soil-air content. Further, compaction effort was much significant for ka than Dp for both fractions. We suggest this is because of compaction effects caused to create well-aligned macropore networks that are available for gas transport through the porous material. Then, the famous predictive models, the water induced linear reduction (WLR) model for Dp and the reference point law (RPL) model for ka were modified with reference point measurements (dry conditions) and model parameters and they correlated linearly to dry bulk density values for both fractions of landfill final cover soil.

Wickramarachchi, P. N.; Kawamoto, K.; Hamamoto, S.; Nagamori, M.; Moldrup, P.; Komatsu, T.

2011-12-01

213

MIDWEST INTERSTATE SULFUR TRANSFORMATION AND TRANSPORT PROJECT: AERIAL MEASUREMENTS OF URBAN AND POWER PLANT PLUMES, SUMMER 1974  

EPA Science Inventory

A portion of the research activities of the Midwest Interstate Sulfur Transformation and Transport Project (Project MISTT) during the summer of 1974 is documented. Using a light plane equipped with instruments for measuring air pollutants and meteorological parameters, investigat...

214

A Transport Analysis of In Situ Airborne Ozone Measurements from the 2011 DISCOVER-AQ Campaign  

NASA Astrophysics Data System (ADS)

Baltimore and Washington are currently designated as nonattainment areas with respect to the 2008 EPA National Ambient Air Quality Standard (NAAQS) for 8-hour Ozone (O3). Tropospheric O3 is the dominant component of summertime photochemical smog, and at high levels, has deleterious effects on human health, ecosystems, and materials. The University of Maryland (UMD) Regional Atmospheric Measurement Modeling and Prediction Program (RAMMPP) strives to improve understanding of air quality in the Mid-Atlantic States and to elucidate contributions of pollutants such as O3 from regional transport versus local sources through a combination of modeling and in situ measurements. The NASA Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) project investigates the connection between column measurements and surface conditions to explore the potential of remote sensing observations in diagnosing air quality at ground level where pollutants can affect human health. During the 2011 DISCOVER-AQ field campaign, in situ airborne measurements of trace gases and aerosols were performed along the Interstate 95 corridor between Baltimore and Washington from the NASA P3B aircraft. To augment this data and provide regional context, measurements of trace gases and aerosols were also performed by the RAMMPP Cessna 402B aircraft over nearby airports in Maryland and Virginia. This work presents an analysis of O3 measurements made by the Ultraviolet (UV) Photometric Ambient O3 Analyzer on the RAMMPP Cessna 402B and by the NCAR 4-Channel Chemiluminescence instrument on the NASA P3B. In this analysis, spatial and temporal patterns of O3 data are examined within the context of forward and backward trajectories calculated from 12-km North American Mesoscale (NAM) meteorological data using the NOAA Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) Model and from a high resolution Weather Research and Forecasting (WRF) model simulation in order to discern O3 resulting from regional transport versus O3 generated photochemically from local pollution sources. During the summer 2011 DISCOVER-AQ field campaign, both aircraft flew on eight overlapping dates. From the spirals performed on those flight days, over 15 cases have been identified where measurements of O3 were performed with one aircraft upwind of the other, based on forward and backward trajectory data. Analysis of these cases indicates that regional transport of O3 is enhanced up to 10% on average by local photochemical O3 production.

Arkinson, H. L.; Brent, L. C.; He, H.; Loughner, C.; Stehr, J. W.; Weinheimer, A. J.; Dickerson, R. R.

2013-12-01

215

Removing traffic emissions from CO2 time series measured at a tall tower using mobile measurements and transport modeling  

NASA Astrophysics Data System (ADS)

In recent years, measurements of atmospheric carbon dioxide with high precision and accuracy have become increasingly important for climate change research, in particular to inform terrestrial biosphere models. Anthropogenic carbon dioxide emissions from fossil fuel burning have long been recognized to contribute a significant portion of the carbon dioxide in the atmosphere. Here, we present an approach to remove the traffic related carbon dioxide emissions from mole fractions measured at a tall tower by using the corresponding carbon monoxide measurements in combination with footprint analyses and transport modeling. This technique improves the suitability of the CO2 data to be used in inverse modeling approaches of atmosphere-biosphere exchange that do not account for non-biotic portions of CO2. In our study region in Oregon, road traffic emissions are the biggest source of anthropogenic carbon dioxide and carbon monoxide. A three-day mobile campaign covering 1700 km of roads in northwestern Oregon was performed during summer of 2012 using a laser-based Cavity Ring-Down Spectrometer. The mobile measurements incorporated different roads including main highways, urban streets, and back-roads, largely within the typical footprint of a tall CO/CO2 observation tower in Oregon's Willamette Valley. For the first time, traffic related CO:CO2 emission ratios were measured directly at the sources during an on-road campaign under a variety of different driving conditions. An average emission ratio of 7.43 (±1.80) ppb CO per ppm CO2 was obtained for the study region and applied to separate the traffic related portion of CO2 from the mole fraction time series. The road traffic related portion of the CO2 mole fractions measured at the tower site reached maximum values ranging from 9.8 to 12 ppm, depending on the height above the surface, during summer 2012.

Schmidt, Andres; Rella, Chris W.; Göckede, Mathias; Hanson, Chad; Yang, Zhenlin; Law, Beverly E.

2014-11-01

216

An overview on the use of backscattered sound for measuring suspended particle size and concentration profiles in non-cohesive inorganic sediment transport studies  

NASA Astrophysics Data System (ADS)

For over two decades, coastal marine scientists studying boundary layer sediment transport processes have been using, and developing, the application of sound for high temporal-spatial resolution measurements of suspended particle size and concentration profiles. To extract the suspended sediment parameters from the acoustic data requires an understanding of the interaction of sound with a suspension of sediments and an inversion methodology. This understanding is distributed around journals in a number of scientific fields and there is no single article that succinctly draws together the different components. In the present work the aim is to provide an overview on the acoustic approach to measuring suspended sediment parameters and assess its application in the study of non-cohesive inorganic suspended sediment transport processes.

Thorne, Peter D.; Hurther, David

2014-02-01

217

Temperature dependent spin transport properties of platinum inferred from spin Hall magnetoresistance measurements  

NASA Astrophysics Data System (ADS)

We study the temperature dependence of the spin Hall magnetoresistance (SMR) in yttrium iron garnet/platinum hybrid structures via magnetization orientation dependent magnetoresistance measurements. Our experiments show a decrease of the SMR magnitude with decreasing temperature. Using the sensitivity of the SMR to the spin transport properties of the normal metal, we interpret our data in terms of a decrease of the spin Hall angle in platinum from 0.11 at room temperature to 0.075 at 10 K, while the spin diffusion length and the spin mixing conductance of the ferrimagnetic insulator/normal metal interface remain almost constant.

Meyer, Sibylle; Althammer, Matthias; Geprägs, Stephan; Opel, Matthias; Gross, Rudolf; Goennenwein, Sebastian T. B.

2014-06-01

218

Temperature dependent spin transport properties of platinum inferred from spin Hall magnetoresistance measurements  

SciTech Connect

We study the temperature dependence of the spin Hall magnetoresistance (SMR) in yttrium iron garnet/platinum hybrid structures via magnetization orientation dependent magnetoresistance measurements. Our experiments show a decrease of the SMR magnitude with decreasing temperature. Using the sensitivity of the SMR to the spin transport properties of the normal metal, we interpret our data in terms of a decrease of the spin Hall angle in platinum from 0.11 at room temperature to 0.075 at 10?K, while the spin diffusion length and the spin mixing conductance of the ferrimagnetic insulator/normal metal interface remain almost constant.

Meyer, Sibylle, E-mail: sibylle.meyer@wmi.badw-muenchen.de; Althammer, Matthias; Geprägs, Stephan; Opel, Matthias; Goennenwein, Sebastian T. B. [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany); Gross, Rudolf [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany); Physik-Department, Technische Universität München, 85748 Garching (Germany)

2014-06-16

219

Gold nanoparticles grown inside carbon nanotubes: synthesis and electrical transport measurements  

NASA Astrophysics Data System (ADS)

The hybrid structures composed of gold nanoparticles and carbon nanotubes were prepared using porous alumina membranes as templates. Carbon nanotubes were synthesized inside the pores of these templates by the non-catalytic decomposition of acetylene. The inner cavity of the supported tubes was used as nanoreactors to grow gold particles by impregnation with a gold salt, followed by a calcination-reduction process. The samples were characterized by transmission electron microscopy and X-ray energy dispersion spectroscopy techniques. The resulting hybrid products are mainly encapsulated gold nanoparticles with different shapes and dimensions depending on the concentration of the gold precursor and the impregnation procedure. In order to understand the electronic transport mechanisms in these nanostructures, their conductance was measured as a function of temperature. The samples exhibit a `non-metallic' temperature dependence where the dominant electron transport mechanism is 1D hopping. Depending on the impregnation procedure, the inclusion of gold nanoparticles inside the CNTs can introduce significant changes in the structure of the tubes and the mechanisms for electronic transport. The electrical resistance of these hybrid structures was monitored under different gas atmospheres at ambient pressure. Using this hybrid nanostructures, small amounts of acetylene and hydrogen were detected with an increased sensibility compared with pristine carbon nanotubes. Although the sensitivity of these hybrid nanostructures is rather low compared to alternative sensing elements, their response is remarkably fast under changing gas atmospheres.

Segura, Rodrigo A.; Contreras, Claudia; Henriquez, Ricardo; Häberle, Patricio; Acuña, José Javier S.; Adrian, Alvaro; Alvarez, Pedro; Hevia, Samuel A.

2014-05-01

220

Measuring rates of intraflagellar transport along Caenorhabditis elegans sensory cilia using fluorescence microscopy.  

PubMed

Intraflagellar transport (IFT), the kinesin-2 and IFT-dynein-dependent bidirectional movement of multisubunit protein complexes called IFT-particles and associated cargo molecules along ciliary axonemes, is thought to be essential for the assembly and maintenance of virtually all eukaryotic cilia and flagella. Transport assays that allow measurements of the rates of movement of specific, fluorescently tagged, functional components of the IFT machinery, including motors, IFT particle subunits, and putative cargo, were first developed in Caenorhabditis elegans sensory cilia, and they have proved to be an important and valuable tool for dissecting the molecular mechanisms of IFT. We describe how these transport assays are performed in our laboratory and summarize the information that has been obtained by using them concerning the mechanisms of action and regulation of the motors that drive IFT, the composition and organization of the IFT-particles, and the identification of IFT-dynein subunits and ciliary tubulin isotypes as likely cargo proteins of kinesin-2-driven anterograde IFT. PMID:23498746

Brust-Mascher, Ingrid; Ou, Guangshuo; Scholey, Jonathan M

2013-01-01

221

Fabrication and transport measurements of stacked double layer topological insulator devices  

NASA Astrophysics Data System (ADS)

A double-layer structure, consisting of two separated two-dimensional electron systems close in proximity, has been an interesting system to study novel ground states and transport properties driven by electron-electron interaction, e.g. Coulomb drag, exciton condensation, and counterflow superfluidity. Recently, topological insulators (TI), such as Bi2Se3 and Bi2Te3, have attracted much attention due to their exotic topologically protected spin-helical and Dirac-particle surface states. Motivated by a recently proposed ``topological exciton condensate'' that may be formed in two interacting TI surfaces, we have fabricated stacking double-layer TI structures and studied their electrical transport properties. Using a polyvinyl alcohol (PVA) based support film and micro-manipulator, double layer TI structures (Bi2Se3/boron nitride/Bi2Se3) were fabricated with exfoliated Bi2Se3 separated by thin boron nitride flakes (˜ 20 nm). We will present results from transport measurements including mutual-gated electrical field effect, Coulomb drag ,and counterflow conductivity.

Wu, Tai-Lung; Hu, Jiuning; Tian, Jifa; Mitkowski, Ireneusz; Chen, Yong P.

2013-03-01

222

Measurement of mass transport and reaction parameters in bulk solution using photobleaching. Reaction limited binding regime.  

PubMed Central

Fluorescence recovery after photobleaching (FRAP) has been used previously to investigate the kinetics of binding to biological surfaces. The present study adapts and further develops this technique for the quantification of mass transport and reaction parameters in bulk media. The technique's ability to obtain the bulk diffusion coefficient, concentration of binding sites, and equilibrium binding constant for ligand/receptor interactions in the reaction limited binding regime is assessed using the B72.3/TAG-72 monoclonal antibody/tumor associated antigen interaction as a model in vitro system. Measurements were independently verified using fluorometry. The bulk diffusion coefficient, concentration of binding sites and equilibrium binding constant for the system investigated were 6.1 +/- 1.1 x 10(-7) cm2/s, 4.4 +/- 0.6 x 10(-7) M, and 2.5 +/- 1.6 x 10(7) M-1, respectively. Model robustness and the applicability of the technique for in vivo quantification of mass transport and reaction parameters are addressed. With a suitable animal model, it is believed that this technique is capable of quantifying mass transport and reaction parameters in vivo. PMID:1932550

Kaufman, E N; Jain, R K

1991-01-01

223

Gold nanoparticles grown inside carbon nanotubes: synthesis and electrical transport measurements  

PubMed Central

The hybrid structures composed of gold nanoparticles and carbon nanotubes were prepared using porous alumina membranes as templates. Carbon nanotubes were synthesized inside the pores of these templates by the non-catalytic decomposition of acetylene. The inner cavity of the supported tubes was used as nanoreactors to grow gold particles by impregnation with a gold salt, followed by a calcination-reduction process. The samples were characterized by transmission electron microscopy and X-ray energy dispersion spectroscopy techniques. The resulting hybrid products are mainly encapsulated gold nanoparticles with different shapes and dimensions depending on the concentration of the gold precursor and the impregnation procedure. In order to understand the electronic transport mechanisms in these nanostructures, their conductance was measured as a function of temperature. The samples exhibit a ‘non-metallic’ temperature dependence where the dominant electron transport mechanism is 1D hopping. Depending on the impregnation procedure, the inclusion of gold nanoparticles inside the CNTs can introduce significant changes in the structure of the tubes and the mechanisms for electronic transport. The electrical resistance of these hybrid structures was monitored under different gas atmospheres at ambient pressure. Using this hybrid nanostructures, small amounts of acetylene and hydrogen were detected with an increased sensibility compared with pristine carbon nanotubes. Although the sensitivity of these hybrid nanostructures is rather low compared to alternative sensing elements, their response is remarkably fast under changing gas atmospheres. PMID:24910571

2014-01-01

224

Turbulent transport and length scale measurement experiments with comfined coaxial jets  

NASA Technical Reports Server (NTRS)

A three phase experimental study of mixing downstream of swirling and nonswirling confined coaxial jets was conducted to obtain data for the evaluation and improvement of turbulent transport models currently employed in a variety of computational procedures. The present effort was directed toward the acquisition of length scale and dissipation rate data that provide more accurate inlet boundary conditions for the computational procedures and a data base to evaluate the turbulent transport models in the near jet region where recirculation does not occur, and the acquisition of mass and momentum turbulent transport data for a nonswirling flow condition with a blunt inner jet inlet configuration rather than the tapered inner jet inlet. A measurement technique, generally used to obtain approximate integral length and microscales of turbulence and dissipation rates, was computerized. Results showed the dissipation rate varied by 2 1/2 orders of magnitude across the inlet plane, by 2 orders of magnitude 51 mm from the inlet plane, and by 1 order of magnitude at 102 mm from the inlet plane for a nonswirling flow test conditions.

Johnson, B. V.; Roback, R.

1984-01-01

225

Incorporation of Fine-Grained Sediment Erodibility Measurements into Sediment Transport Modeling, Capitol Lake, Washington  

USGS Publications Warehouse

Capitol Lake was created in 1951 with the construction of a concrete dam and control gate that prevented salt-water intrusion into the newly formed lake and regulated flow of the Deschutes River into southern Puget Sound. Physical processes associated with the former tidally dominated estuary were altered, and the dam structure itself likely caused an increase in retention of sediment flowing into the lake from the Deschutes River. Several efforts to manage sediment accumulation in the lake, including dredging and the construction of sediment traps upriver, failed to stop the lake from filling with sediment. The Deschutes Estuary Feasibility Study (DEFS) was carried out to evaluate the possibility of removing the dam and restoring estuarine processes as an alternative ongoing lake management. An important component of DEFS was the creation of a hydrodynamic and sediment transport model of the restored Deschutes Estuary. Results from model simulations indicated that estuarine processes would be restored under each of four restoration alternatives, and that over time, the restored estuary would have morphological features similar to the predam estuary. The model also predicted that after dam-removal, a large portion of the sediment eroded from the lake bottom would be deposited near the Port of Olympia and a marina located in lower Budd Inlet seaward of the present dam. The volume of sediment transported downstream was a critical piece of information that managers needed to estimate the total cost of the proposed restoration project. However, the ability of the model to predict the magnitude of sediment transport in general and, in particular, the volume of sediment deposition in the port and marina was limited by a lack of information on the erodibility of fine-grained sediments in Capitol Lake. Cores at several sites throughout Capitol Lake were collected between October 31 and November 1, 2007. The erodibility of sediments in the cores was later determined in the lab with Sedflume, an apparatus for measuring sediment erosion-parameters. In this report, we present results of the characterization of fine-grained sediment erodibility within Capitol Lake. The erodibility data were incorporated into the previously developed hydrodynamic and sediment transport model. Model simulations using the measured erodibility parameters were conducted to provide more robust estimates of the overall magnitudes and spatial patterns of sediment transport resulting from restoration of the Deschutes Estuary.

Stevens, Andrew W.; Gelfenbaum, Guy; Elias, Edwin; Jones, Craig

2008-01-01

226

Stability and performance characteristics of a fixed arrow wing supersonic transport configuration (SCAT 15F-9898) at Mach numbers from 0.60 to 1.20  

NASA Technical Reports Server (NTRS)

Tests on a 0.015 scale model of a supersonic transport were conducted at Mach numbers from 0.60 to 1.20. Tests of the complete model with three wing planforms, two different leading-edge radii, and various combinations of component parts, including both leading- and trailing-edge flaps, were made over an angle-of-attack range from about -6 deg to 13 deg and at sideslip angles of 0 deg and 2 deg.

Decker, J. P.; Jacobs, P. F.

1978-01-01

227

Bedload transport formulae calibration using a single measurement: testing high and low  

NASA Astrophysics Data System (ADS)

Due to the difficulty in accurately predicting bedload transport using traditional equations, bedload samples are often collected in the field and used to calibrate predictions. However, sampling bedload is time consuming and expensive. In lieu of conducting an exhaustive sampling campaign in the field, some researchers have recommended collecting one to three low flow samples in the field. This work addresses the question of whether a single bedload measurement near bankfull is more successful at calibrating a predictive equation than a low flow measurement. The Pagosa Good/Fair, Wilcock Surface-based Two Fraction, and Barry et al. General Power Equation formulae are compared using a single calibration point at low flow and then another at bankfull discharge. The comparison is conducted using 2,500 measurements from a database of a total of 8,000 available measurements. The results show that a measurement at bankfull is a better predictor than a low flow measurement, but acceptable results at low flow are provided by the Pagosa and Barry formulae. This work also recommends that sampling methodology be a consideration for formula selection. In other words, certain formulae work better for Helley-Smith samplers while others are better suited for data collected in net or pit traps. For example, the predictive curve produced by the Pagosa and Barry formulae better fit Helley-Smith data than the Wilcock, which is recommended for data collected in net or pit traps.

Hinton, D. D.; Hotchkiss, R. H.

2012-12-01

228

Permalloy and Co50Pd50 as ferromagnetic contacts for magnetoresistance measurements in carbon nanotube-based transport structures  

NASA Astrophysics Data System (ADS)

In this paper, magnetoresistance (MR) measurements on carbon nanotube (CNT) 2-terminal spin-valve devices are presented. Results from samples with both permalloy (Py) and CoPd contacts show repeatable MR switching. In performing gate-dependent MR measurements on the Py-contacted CNTs, two distinct transport regimes are identified, and their transport behavior is discussed with respect to optimizing MR. Results from the first CoPd-contacted CNTs indicate a stable magnetic response with a higher magnitude than that of a Py-contacted nanotube in the same transport regime.

Morgan, Caitlin; Schneider, Claus M.; Meyer, Carola

2012-04-01

229

Barrow Arch transportation-systems impact analysis. Social and economic studies program technical report number 104. Final report  

SciTech Connect

This report evaluates future effects on regional air, marine, highway, rail, and pipeline transportation systems from Outer Continental Shelf (OCS) petroleum development in offshore location known as the (Barrow Arch) Chukchi Sea Planning area. Future conditions without the OCS development mostly represent an extrapolation of current trends and conditions, while future conditions with the development are driven by an industrial-development scenario prepared by MMS. The analysis looked at transportation services to the nearby North Slope Eskimo coastal villages of Point Lay, Point Hope, Wainwright, and Barrow; the more southerly coastal communities of Kivilina and Kotzebue, and the petroleum industry enclave at Prudhoe Bay/Deadhorse.

Not Available

1984-12-01

230

Introducing Percents in Linear Measurement To Foster an Understanding of Rational-Number Operations.  

ERIC Educational Resources Information Center

Describes the kinds of computational abilities achieved by a class of 4th grade students who were part of a research program for teaching rational numbers. In this program, students build on intuitive understandings of percents and proportions for the development of overall understanding of the number system and are encouraged to invent their own…

Moss, Joan

2003-01-01

231

Airborne High Spectral Resolution Lidar Aerosol Measurements and Comparisons with Transport Models  

NASA Astrophysics Data System (ADS)

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) measured aerosol distributions and optical properties during several field experiments in 2006 and 2007. These experiments include: 1) the joint Megacity Initiative: Local and Global Research Observations (MILAGRO) /Megacity Aerosol Experiment in Mexico City (MAX-MEX)/Intercontinental Chemical Transport Experiment-B (INTEX B) experiment, 2) the Texas Air Quality Study (TEXAQS)/Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS), 3) the San Joaquin Valley experiment, 4) the Cumulus Humilis Aerosol Processing Study (CHAPS), and 5) the Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and Twilight Zone (CATZ) experiment. The LaRC airborne HSRL uses the spectral distribution of the lidar return signal to measure aerosol extinction and backscatter profiles independently at 532 nm and uses standard backscatter lidar techniques to derive aerosol backscatter and extinction profiles at 1064 nm. Aerosol depolarization profiles are measured at both wavelengths. The HSRL collected over 350 hours of aerosol measurements during these experiments. Airborne HSRL data acquired during these missions were used to infer aerosol types, characterize the spatial and vertical distributions of these aerosol types, and to apportion aerosol extinction and optical thickness (AOT) among the various aerosol types. Initial results show that a mixture of nonspherical (i.e. dust) and urban aerosols accounted for over half of the AOT measured by the HSRL during the MILAGRO flights over Mexico; in contrast, during the GoMACCS and CALIPSO validation flights over Houston and the eastern U.S., respectively, urban/biomass aerosols accounted for 80-90% of the AOT. Preliminary investigations using airborne in situ measurements of aerosol microphysical properties generally support the variability of aerosol types inferred from the HSRL data. The distributions of aerosol extinction, optical thickness, and aerosol types in relation to the Planetary Boundary Layer (PBL) and free troposphere will also be discussed. The HSRL measurements were also used to help evaluate the ability of transport models to reproduce aerosol extinction and optical thickness profiles and represent horizontal and vertical variations in aerosol types. This presentation will describe how the HSRL measurements were used to assess these models as well as how the model simulations were used to help interpret the HSRL measurements. Simulations from several models will be discussed.

Ferrare, R.; Hostetler, C.; Hair, J.; Cook, A.; Harper, D.; Burton, S.; Obland, M.; Rogers, R.; Kleinman, L.; Clarke, A.; Fast, J.; Chin, M.; Carmichael, G.; Tang, Y.; Emmons, L.; Pierce, B.; Kittaka, C.

2007-12-01

232

Measuring and modelling the local-scale spatio-temporal variation of urban particle number size distributions and black carbon  

NASA Astrophysics Data System (ADS)

Mobile measurements were performed to study the spatio-temporal variation of particle number size distributions (NSD) in the range 11 < Dp < 365 nm as well as total particle number and black carbon concentrations in Braunschweig, Germany during the winter and summer period 2012/2013. The study area of about 1 km2 consisted of six different outdoor microenvironments (ME) that were classified according to different traffic intensities and dominant land use types along the measurement route. Highest averaged total number concentrations measured at roadside (RO) were 2.5 × 104 pt cm-3 (with a maximum of 7.6 × 104 pt cm-3) during winter and about 1.2 × 104 pt cm-3 on average during the summer campaign. Measurement spots which are more distant to traffic were characterised by lower concentrations of 1.6 × 104 pt cm-3 and 9.0 × 103 pt cm-3 during winter and summer, respectively. Black carbon (BC) concentrations were also clearly related to traffic emissions and resulted in concentrations of 2.8 ?g m-3 on average (absolute maximum of 6.2 ?g m-3) at RO-sites. The concentrations of particles and BC in the different ME (aggregated from the single measurement spots) documented the concentration of both metrics to be a function of distance of the measurement to fresh traffic emissions. A multiple regression based model was established to identify significant parameters which can be used to model the microscale variation of particle NSD in the outdoor ME. Two models with different numbers of input parameters were calculated. The first contained all measured parameters as input, the second only a reduced number consisting of TNC, BC and wind speed. Both models worked convincingly, even the approach with the limited number of input parameters. The average size integrated (TNC) deviation to observed data in all ME during both seasons was <13%. The best agreement between model and observations is given for the near-traffic ME.

Ruths, Matthias; von Bismarck-Osten, Clemens; Weber, Stephan

2014-10-01

233

The Australian methane budget: Interpreting surface and train-borne measurements using a chemistry transport model  

NASA Astrophysics Data System (ADS)

We investigate the Australian methane budget from 2005-2008 using the GEOS-Chem 3D chemistry transport model, focusing on the relative contribution of emissions from different sectors and the influence of long-range transport. To evaluate the model, we use in situ surface measurements of methane, methane dry air column average (XCH4) from ground-based Fourier transform spectrometers (FTSs), and train-borne surface concentration measurements from an in situ FTS along the north-south continental transect. We use gravity anomaly data from Gravity Recovery and Climate Experiment to describe the spatial and temporal distribution of wetland emissions and scale it to a prior emission estimate, which better describes observed atmospheric methane variability at tropical latitudes. The clean air sites of Cape Ferguson and Cape Grim are the least affected by local emissions, while Wollongong, located in the populated southeast with regional coal mining, samples the most locally polluted air masses (2.5% of the total air mass versus <1% at other sites). Averaged annually, the largest single source above background of methane at Darwin is long-range transport, mainly from Southeast Asia, accounting for ˜25% of the change in surface concentration above background. At Cape Ferguson and Cape Grim, emissions from ruminant animals are the largest source of methane above background, at approximately 20% and 30%, respectively, of the surface concentration. At Wollongong, emissions from coal mining are the largest source above background representing 60% of the surface concentration. The train data provide an effective way of observing transitions between urban, desert, and tropical landscapes.

Fraser, Annemarie; Chan Miller, Christopher; Palmer, Paul I.; Deutscher, Nicholas M.; Jones, Nicholas B.; Griffith, David W. T.

2011-10-01

234

Measurement of the Critical Deposition Velocity in Slurry Transport through a Horizontal Pipe  

SciTech Connect

Critical Deposition Velocity (CDV) is an important design and operational parameter in slurry transport. Almost all existing correlations that are used to predict this parameter have been obtained experimentally from slurry transport tests featuring single solid species in the slurry mixture. No correlations have been obtained to describe this parameter when the slurry mixture contains more than one solid species having a wide range of specific gravities, particle size distributions, and volume concentrations within the overall slurry mixture. There are no physical or empirical bases that can justify the extrapolation or modification of the existing single species correlations to include all these effects. New experiments must be carried out to obtain new correlations that would be suited for these types of slurries, and that would clarify the mechanics of solids deposition as a function of the properties of the various solid species. Our goal in this paper is to describe a robust experimental technique for the accurate determination of the critical deposition velocity associated with the transport of slurries in horizontal or slightly inclined pipes. Because of the relative difficulty encountered during the precise determination of this useful operational parameter, it has been the practice to connect it with some transitional behavior of more easily measurable flow parameters such as the pressure drop along the slurry pipeline. In doing so, the critical deposition velocity loses its unique and precise definition due to the multitude of factors that influence such transitional behaviors. Here, data has been obtained for single species slurries made up of washed garnet and water and flowing through a 1- inch clear pipe. The selected garnet had a narrow particle size distribution with a mean diameter of 100 mm, approximately. The critical deposition velocity was measured for garnet/water slurries of 10, 20, and 30 percent solids concentration by volume.

Erian, Fadel F.; Furfari, Daniel J.; Kellogg, Michael I.; Park, Walter R.

2001-03-01

235

Spray washing, absorbent corn starch powder and dry time to reduce bacterial numbers on soiled boiler transport cage flooring  

Technology Transfer Automated Retrieval System (TEKTRAN)

Most broilers in the U.S. are transported live to slaughter facilities in cages with fiberglass floors. Cages are often used repeatedly without washing and fecal matter deposited on the floor surface can transfer Campylobacter from one flock to another. Drying feces out between uses is an effectiv...

236

Electrical Resistivity Measurements of Layer Number Determined Multilayer Graphene Wiring for Future Large Scale Integrated Circuit Interconnects  

NASA Astrophysics Data System (ADS)

To investigate the feasibility of nanocarbon interconnects for future LSIs, the electrical resistance of exfoliated multilayer graphene (MLG) wirings has been studied with accurate measurements of the number of layers. We employed transmission electron microscopy (TEM) as an exact number determination method, atomic force microscopy (AFM) as a simple method, and an extended optical contrast method as an easy distinction method, which we proposed for determining the number of layers. The sheet resistance of MLG wirings, including TEM determined 3-, 54-, and 341-layer MLGs, has been measured using the four-probe method and the layer number dependence of sheet resistance was discussed on the basis of a ladder circuit model simulation. It is shown that the dependence agrees well with the simulations, suggesting parallel conduction in MLG wirings, even if the probe electrodes are deposited just on the top layer of MLG.

Ito, Kazuyuki; Katagiri, Masayuki; Sakai, Tadashi; Awano, Yuji

2013-06-01

237

Impurity transport measurements in the PISCES-A linear plasma device  

NASA Astrophysics Data System (ADS)

The parallel transport, in terms of diffusion and advection by entrainment in parallel plasma flow, of impurities relevant to proposed ITER divertor materials (W, C) are studied in a linear He plasma. Introduction of the impurities in controlled amounts is accomplished by blow-off of thin films using a (1064nm, 75 mJ) pulsed Nd:Yag laser. Neutral and ion excited state emission are measured with an optically filtered PMT array. Emission profiles are compared to a 1.5 D advection plus diffusion numerical model to obtain a parallel flow speed and parallel and perpendicular diffusion coefficients. This work also expands on earlier results [1] by including multiple downstream measurement locations to quantify impurity acceleration and the controlled spot size of impurity blow-off. [4pt] [1] E. M. Hollmann et. al., J. Nucl. Mater (2010) in press

Hudson, B. F.; Doerner, R. P.; Hollmann, E. M.; Nishijima, D.

2011-11-01

238

Rapid Measurement of Molecular Transport and Interaction inside Living Cells Using Single Plane Illumination  

PubMed Central

The ability to measure biomolecular dynamics within cells and tissues is very important to understand fundamental physiological processes including cell adhesion, signalling, movement, division or metabolism. Usually, such information is obtained using particle tracking methods or single point fluctuation spectroscopy. We show that image mean square displacement analysis, applied to single plane illumination microscopy data, is a faster and more efficient way of unravelling rapid, three-dimensional molecular transport and interaction within living cells. From a stack of camera images recorded in seconds, the type of dynamics such as free diffusion, flow or binding can be identified and quantified without being limited by current camera frame rates. Also, light exposure levels are very low and the image mean square displacement method does not require calibration of the microscope point spread function. To demonstrate the advantages of our approach, we quantified the dynamics of several different proteins in the cyto- and nucleoplasm of living cells. For example, from a single measurement, we were able to determine the diffusion coefficient of free clathrin molecules as well as the transport velocity of clathrin-coated vesicles involved in endocytosis. Used in conjunction with dual view detection, we further show how protein-protein interactions can be quantified. PMID:25394360

Hedde, Per Niklas; Stakic, Milka; Gratton, Enrico

2014-01-01

239

SO2 measurements at a high altitude site in the central Himalayas: Role of regional transport  

NASA Astrophysics Data System (ADS)

Continuous measurements of a climatically important acidic gas, SO2, were made over Nainital (29.37°N, 79.45°E; 1958 m amsl), a regionally representative site in the central Himalayas, for the first time during 2009-2011. Unlike many other sites, the SO2 levels over Nainital are higher during pre-monsoon (345 pptv) compared to winter (71 pptv). High values during pre-monsoon are attributed to the transport of air masses from regions viz. Indo-Gangetic Plain (IGP), northern India and north-East Pakistan, which are dotted with numerous industries and power plants, where coal burning occurs. Transport from the polluted regions is evinced from good correlations of SO2 with wind speed, NOy and UV aerosol index during these periods. Daytime elevations in SO2 levels, influenced by 'valley winds' and boundary layer evolution, is a persistent feature at Nainital. SO2 levels are very much lower during monsoon compared to pre-monsoon, due to oxidation losses and wet scavenging. Despite this, SO2/NOy slopes are high (>0.4) both during pre-monsoon and monsoon, indicating impacts of point sources. The SO2 levels during winter are lower as the measurement site is cut off from the plains due to boundary layer dynamics. Further, the SO2 levels during winter nights are the lowest (lesser than 50 pptv) and resemble free tropospheric conditions.

Naja, Manish; Mallik, Chinmay; Sarangi, Tapaswini; Sheel, Varun; Lal, Shyam

2014-12-01

240

In situ measurements of particulate number density and size distribution from an aircraft. [using light scattering particle counter  

NASA Technical Reports Server (NTRS)

Two different commercial particulate measuring instruments were flown aboard the NASA Convair 990. A condensation nuclei monitor was utilized to measure particles larger than approximately 0.003 micron in diameter. A specially designed pressurization system was used with this monitor at cabin altitude pressure. A near-forward light scattering counter was used to measure the number and size distribution particles in the size range from 0.5 to 5 microns and greater in diameter. Considerable variation in number density was encountered for both classes of particles at the test altitudes ranging from 5 to 12 km. Presence of clouds could be detected by the light scattering instrument because large numbers of particles would then be registered by the instrument, especially in the size range above 5.0 microns in diameter.

Briehl, D.

1974-01-01

241

Fundamental mismatches between measurements and models in aeolian sediment transport prediction: The role of small-scale variability  

NASA Astrophysics Data System (ADS)

Predicting aeolian sediment transport is a long-standing and difficult challenge that is important to a variety of scientific disciplines, including geology, geomorphology, agriculture, meteorology, and climatology. Here, we argue that improvements in predictions of aeolian sediment transport are limited by incompatibilities between empirical measurements and mathematical models. We focus on the spatial and temporal variability in transport. Measurements indicate considerable variability on small time (second) and length (meter) scales, yet models are almost ubiquitously based on assumptions of time and space-invariant transport. Mismatches between measurements and models limit summative predictive capacity by reducing the ability to use measured data to test and drive models. We suggest: (i) revising model conceptualizations and evaluating the representativeness of steady state saltation to constrain the realism of existing models, (ii) improving and optimizing measurement technology to produce more reliable and accurate measurements, (iii) explicitly specifying the scale of measurements, and (iv) designing variable matching tests between models and measurements to work around measurement limitations. Continuing with the status quo, where measurements and models are dealt with separately, is likely to erode summative predictive capacity.

Barchyn, Thomas E.; Martin, Raleigh L.; Kok, Jasper F.; Hugenholtz, Chris H.

2014-12-01

242

Measurement of effective atomic number of gunshot residues using scattering of gamma rays  

NASA Astrophysics Data System (ADS)

Better understanding of gunshot residues and the major elemental composition would be valuable to forensic scientists for their analysis work and interpretation of results. In the present work, the effective atomic numbers of gunshot residues (cartridge case, bullet core, bullet jacket and gunpowder) were analyzed using energy dispersive X-ray analysis (EDX). The scattering of 59.54 keV gamma rays is studied using a high-resolution HPGe detector. The experiment is performed on various elements with atomic number in the 4?Z?82. The intensity ratio of coherent to Compton scattered peaks, corrected for photo-peak efficiency of gamma detector and absorption of photons in the sample and air, is plotted as a function of atomic number and constituted a best-fit-curve. From this fit-curve, the respective effective atomic numbers of gunshot residues are determined.

Y?lmaz, Demet; Tur?ucu, Ahmet; Uzuno?lu, Zeynep; Korucu, Demet

2014-09-01

243

Quantitative measurements and modeling of cargo-motor interactions during fast transport in the living axon  

NASA Astrophysics Data System (ADS)

The kinesins have long been known to drive microtubule-based transport of sub-cellular components, yet the mechanisms of their attachment to cargo remain a mystery. Several different cargo-receptors have been proposed based on their in vitro binding affinities to kinesin-1. Only two of these—phosphatidyl inositol, a negatively charged lipid, and the carboxyl terminus of the amyloid precursor protein (APP-C), a trans-membrane protein—have been reported to mediate motility in living systems. A major question is how these many different cargo, receptors and motors interact to produce the complex choreography of vesicular transport within living cells. Here we describe an experimental assay that identifies cargo-motor receptors by their ability to recruit active motors and drive transport of exogenous cargo towards the synapse in living axons. Cargo is engineered by derivatizing the surface of polystyrene fluorescent nanospheres (100 nm diameter) with charged residues or with synthetic peptides derived from candidate motor receptor proteins, all designed to display a terminal COOH group. After injection into the squid giant axon, particle movements are imaged by laser-scanning confocal time-lapse microscopy. In this report we compare the motility of negatively charged beads with APP-C beads in the presence of glycine-conjugated non-motile beads using new strategies to measure bead movements. The ensuing quantitative analysis of time-lapse digital sequences reveals detailed information about bead movements: instantaneous and maximum velocities, run lengths, pause frequencies and pause durations. These measurements provide parameters for a mathematical model that predicts the spatiotemporal evolution of distribution of the two different types of bead cargo in the axon. The results reveal that negatively charged beads differ from APP-C beads in velocity and dispersion, and predict that at long time points APP-C will achieve greater progress towards the presynaptic terminal. The significance of this data and accompanying model pertains to the role transport plays in neuronal function, connectivity, and survival, and has implications in the pathogenesis of neurological disorders, such as Alzheimer’s, Huntington and Parkinson's diseases.

Seamster, Pamela E.; Loewenberg, Michael; Pascal, Jennifer; Chauviere, Arnaud; Gonzales, Aaron; Cristini, Vittorio; Bearer, Elaine L.

2012-10-01

244

Laboratory Measurements of Fluid Transport Properties on Tight Gas Sandstones and Applications  

NASA Astrophysics Data System (ADS)

Deep gas reservoirs are of great interest for the E&P industry. Large areas of such reservoirs have permeabilities below 1 mD. The reservoir rocks in these areas show a strong stress sensitivity of the fluid transport properties and a considerable productivity decline due to changing stress conditions during the production process. For correct modeling and simulation of Tight Gas reservoirs it is important to know the behavior of the fluid transport properties under the changing stress condition the reservoir experiences. In several measurement series the effects of changing overburden and pore pressure on Rotliegend sandstone samples from north German Tight Gas reservoirs have been quantified and used to set up correlation functions. With the correlation functions from the own measurements and additional data and correlations from literature a Rock Data Catalog has been developed as tool to help reservoir engineers with modeling and simulation of such reservoirs. The Rock Data Catalog consists of the Rock Database and the Correlation Module. The Rock Database contains general and petrophysical rock data. The Correlation Module uses this data to generate secondary data of e.g. in-situ capillary and hydraulic rock properties with appropriate correlation functions. Viability of the economic gas production from Tight Gas Reservoirs strongly depends on reservoir quality. Therefore identification of high quality reservoir parts or so called Sweet Spots for placing production wells and planning hydraulic fracturing stimulation, is one of key issues of the tight gas reservoir characterization and evaluation. The data and correlation functions collected in the Rock Data Catalog could also be used to identify Sweet Spots in Tight Gas reservoirs. Several rock parameters and properties, which affect the fluid flow in a reservoir (like lithology, clay content, water saturation, permeability, pore size distribution) can be identified and used to set up a Sweet Spot Index as a measure for the reservoir quality.

Albrecht, Daniel; Reitenbach, Viktor

2014-05-01

245

Mesoscale Backtracking by Means of Atmospheric Transport Modeling of Xenon Plumes Measured by Radionuclide Gas Stations  

NASA Astrophysics Data System (ADS)

The monitoring of atmospheric radioactive xenon concentration is performed for nuclear safety regulatory requirements. It is also planned to be used for the detection of hypothetical nuclear tests in the framework of the Comprehensive nuclear-Test-Ban Treaty (CTBT). In this context, the French Atomic Energy Commission designed a high sensitive and automated fieldable station, named SPALAX, to measure the activity concentrations of xenon isotopes in the atmosphere. SPALAX stations were set up in Western Europe and have been operated quite continuously for three years or more, detecting principally xenon-133 and more scarcely xenon-135, xenon-133m and xenon-131m. There are around 150 nuclear power plants in the European Union, research reactors, reprocessing plants, medical production and application facilities releasing radioactive xenon in normal or incidental operations. A numerical study was carried out aiming to explain the SPALAX measurements. The mesoscale Atmospheric Transport Modelling involves the MM5 suite (PSU- NCAR) to predict the wind fields on nested domains, and FLEXPART, a 3D Lagrangian particle dispersion code, used to simulate the backward transport of xenon plumes detected by the SPALAX. For every event of detection, at least one potential xenon source has a significant efficiency of emission. The identified likely sources are located quite close to the SPALAX stations (some tens of kilometres), or situated farther (a few hundreds of kilometres). A base line of some mBq per cubic meter in xenon-133 is generated by the nuclear power plants. Peaks of xenon-133 ranging from tens to hundreds of mBq per cubic meter originate from a radioisotope production facility. The calculated xenon source terms required to obtain the SPALAX measurements are discussed and seem consistent with realistic emissions from the xenon sources in Western Europe.

Armand, P. P.; Achim, P.; Taffary, T.

2006-12-01

246

Measuring Relevant Properties of Cohesive Sediment Aggregates ("Flocks") for Sediment Transport Modeling  

NASA Astrophysics Data System (ADS)

Improvements to nearshore sediment transport models require increased fidelity and new data on the strength, density, structure and size of cohesive sediment aggregates or "flocs". To facilitate this, we developed new methods to evaluate flocculated sediments and the results that were generated facilitate improved numerical simulations of suspended and bedload sediment transport. Typically, flocs originate as aggregated clumps of clays and organic matter (e.g., biopolymers, humic acids) that chemically bond when they enter saline water, such that the floc particle grows in size until it is often orders of magnitude larger than the constituent particles. This important factor yields settling velocities for flocs that are orders of magnitude faster than that of the primary particles. Our recent work has compared the relationship of biopolymer-clay and clay-clay flocs in laboratory experiments that were conducted on synthetic (i.e., produced in the lab) and natural flocs (i.e., gathered from coastal estuaries). The size, shape and density of flocs directly impact transport properties such as hydrodynamic drag, hindered settling velocity and density, which are further altered by floc compressive and shear strength. Due to an inability to measure these transport and strength properties in situ on individual flocs, settling velocity of individual flocs has often been related to the fractal dimensionality, which is an indication of floc porosity, density and strength. Therefore, this work has correlated settling velocity with fractal dimensionality for both types of flocs in initial studies. Then in order to address the influence of flow velocity and fluid shear stress on floc shape and size, both floc types were entrained in a flow-through particle size analyzer to establish correlations between turbulent flow velocity and floc size modality. The compressive strength of these flocs was addressed directly by subjecting them to high-resolution (50 nN sensitivity) compression tests that provides a determination of the elastic modulus and yield shear strength. These data are requisite components of a sediment transport model that uses the discrete element method (DEM) to determine how particles respond to particle collisions within the water column. To address the influence consolidation of flocs that were deposited on the seafloor, a micro/nano-cone penetrometer was developed. This test uses a mm-sized cone that is coupled to a high-resolution load cell so that the strength of the top few mm of the newly formed seabed can be characterized in terms of bearing capacity and undrained shear strength. This data will be used to drive numerical simulations of cohesive bedload entrainment, transport and resuspension. Ultimately, these assessments will provide realistic and useful data to facilitate and improve various modeling efforts, which simulate and predict suspended sediment and bedload transport in estuarine and nearshore coastal environments where cohesive sediments abound.

Reed, A. H.; Zhang, G.; Tan, X.; Yin, H.; Furukawa, Y.

2012-12-01

247

Absolute wave-number measurements in 130Te2: reference lines spanning the 420.9-464.6-nm region  

NASA Astrophysics Data System (ADS)

We have measured the absolute wave numbers of 39 transitions of 130Te2 spanning the spectral region of 420.9-464.6 nm to an accuracy of better than 2 parts in 109 by use of saturation spectroscopy and Fabry-Pérot interferometry. These measurements provide a set of convenient and accurate transfer standards for laser wavelength calibration spanning the entire Stilbene-420 dye-tuning curve.

Scholl, T. J.; Rehse, S. J.; Holt, R. A.; Rosner, S. D.

2005-05-01

248

Transport Measurements on a Two-Dimensional Wigner Crystal Near Melting.  

NASA Astrophysics Data System (ADS)

Experimentally, the reciprocal mobility, mu^{-1}, of a Wigner lattice of electrons above liquid helium is known to exhibit a narrow maximum for a temperature just below the melting temperature, T_{rm m}, of the lattice. Within the same interval of temperature, the electron effective mass, m^*, is observed to decrease monotonically as T_ {rm m} is approached from below. We begin with a discussion of the features in our mu^{-1} and m^* data, near T_ {rm m}, within the framework of the grain boundary induced melting theory of Chui, and the dislocation mediated melting theory of Kosterlitz and Thouless, Halperin and Nelson, and Young. The features in our transport data, near T_{rm m}, are consistent with what one expects in the continuous melting theory of Kosterlitz and Thouless, Halperin and Nelson, and Young. In addition, our data appears to rule out a strongly 1^{ rm st} order transition of the type proposed by Chui. Next, we investigate a model for additional phonon -ripplon scattering, near T_{rm m}, based on the melting theory of Kosterlitz and Thouless, Halperin and Nelson, and Young. In the model, edge dislocations moving in response to a time dependent applied strain produce phonons, resulting in enhanced phonon -ripplon scattering near T_{rm m}. A detailed calculation showed, however, that the magnitude of the observed maximum in mu^{-1} is inconsistent with that given in this model. Also, electron fluid mobility, electron lattice mobility, and electron effective mass data are presented as a function of the vertical pressing field and excitation frequency, for temperatures outside of the critical region. These data are compared with existing transport theories. The experiments were performed on a newly constructed, continuous ^3He refrigerator, allowing one to make transport measurements at temperatures as low as 0.36^circK. The mobility cell used it in these experiments is also new. The essential differences between it and earlier versions used by colleagues for similar measurements are: the use of a guard electrode surrounding the bottom signal electrodes, allowing one to make constant electron density, variable pressing field measurements, and a reduction in the cell's physical dimensions for possible usage inside a 6.0 Tesla superconducting solenoid.

Stan, Mark Anthony

249

An Analysis and Review of Measures and Relationships in Space Transportation Affordability  

NASA Technical Reports Server (NTRS)

The affordability of transportation to or from space is of continued interest across numerous and diverse stakeholders in our aerospace industry. Such an important metric as affordability deserves a clear understanding among stakeholders about what is meant by affordability, costs, and related terms, as otherwise it's difficult to see where specific improvements are needed or where to target specific investments. As captured in the famous words of Lewis Carroll, "If you don't know where you are going, any road will get you there". As important as understanding a metric may be, with terms such as costs, prices, specific costs, average costs, marginal costs, etc., it is equally important to understand the relationship among these measures. In turn, these measures intermingle with caveats and factors that introduce more measures in need of a common understanding among stakeholders. These factors include flight rates, capability, and payload. This paper seeks to review the costs of space transportation systems and the relationships among the many factors involved in costs from the points of view of diverse decision makers. A decision maker may have an interest in acquiring a single launch considering the best price (along with other factors in their business case), or an interest in many launches over time. Alternately, a decision maker may have a specific interest in developing a space transportation system that will offer certain prices, or flight rate capability, or both, at a certain up-front cost. The question arises for the later, to reuse or to expend? As it is necessary in thinking about the future to clearly understand the past and the present, this paper will present data and graphics to assist stakeholders in visualizing trends and the current state of affairs in the launch industry. At all times, raw data will be referenced (or made available separately) alongside detailed explanations about the data, so as to avoid the confusion or misleading conclusions that occur more often than not with complex graphs or statements when such context is lacking.

Zapata, Edgar; McCleskey, Carey

2014-01-01

250

Measurement of resistance to solute transport across surfactant-laden interfaces using a Fluorescence Recovery After Photobleaching (FRAP) technique  

NASA Technical Reports Server (NTRS)

A noninvasive fluorescence recovery after photobleaching (FRAP) technique is under development to measure interfacial transport in two phase systems without disturbing the interface. The concentration profiles of a probe solute are measured in both sides of the interface by argon-ion laser, and the system relaxation is then monitored by a microscope-mounted CCD camera.

Browne, Edward P.; Nivaggioli, Thierry; Hatton, T. Alan

1994-01-01

251

Electric energy measurement in digital substation on a number of issues discussed  

Microsoft Academic Search

With the breakthrough of electrooptical technology research on sensor application, the promulgation of IEC 61850, the application of Ethernet communication technology and the development of intelligent breaker, digital substation has become the mainstream of substation automation technology development in future. This paper briefly discusses issues related to electric energy measurement in digital substation, including the differences between electric energy measurement

Jun Rong; Gui-Xin Zhang; Xiao-Mei Zhu; Peng Wang

2008-01-01

252

Electrical Noise and the Measurement of Absolute Temperature, Boltzmann's Constant and Avogadro's Number.  

ERIC Educational Resources Information Center

Describes an apparatus capable of measuring absolute temperatures of a tungsten filament bulb up to normal running temperature and measuring Botzmann's constant to an accuracy of a few percent. Shows that electrical noise techniques are convenient to demonstrate how the concept of temperature is related to the micro- and macroscopic world. (CW)

Ericson, T. J.

1988-01-01

253

Measurement of optical-transport coefficients of Intralipid in visible and NIR range  

NASA Astrophysics Data System (ADS)

This article presents a modified method of measuring the optical-transport-coefficients of intralipid: the diffuse reflectance of intralipid with added-ink Rdink is measured by using an integrating sphere to calculate the scattering coefficient (mu) 's, the effective attenuation coefficient (mu) eff is measured by scanning the surface of pure intralipid suspension with a cut-end, high NA fiber-optic tip ((phi) 600micrometers , NA equals 0.48) in order to directly derive the absorption (mu) a of pure intralipid. In the same way, their wavelength dependencies between 0.48 - 0.85 micrometers are measured by utilizing Ar+, dye and Ti:Sapphire lasers. Experiments show that (mu) s((lambda) ) varies with (lambda) according to the previously reported Mie theory, (mu) 's((lambda) ) decreases with (lambda) while Rdink((lambda) ) is nearly invariant within the wavelength range; the scattering anisotropy g((lambda) ) tends to decrease linearly with (lambda) from 0.91 to 0.78; (mu) a((lambda) ) first decreases with (lambda) till (lambda) approximately equals 0.61 micrometers and then gradually increases with (lambda) . In the Rdink experiments, it has been found that when the port of the integrating sphere is lifted above the liquid surface, the dependence of the measured intensity with the height H can be well-fitted into an exponential relation for H measured points to H equals 0. Monte-Carlo simulation is applied to analyze the results.

Pan, Yingtian; Engelhardt, R.; Rosperich-Palm, Juergen; Huettmann, Gereon; Birngruber, Reginald

1994-08-01

254

Measurement of quasi-ballistic heat transport across nanoscale interfaces using ultrafast coherent soft x-ray beams  

SciTech Connect

Understanding heat transport on nanoscale dimensions is important for fundamental advances in nanoscience, as well as for practical applications such as thermal management in nano-electronics, thermoelectric devices, photovoltaics, nanomanufacturing, as well as nanoparticle thermal therapy. Here we report the first time-resolved measurements of heat transport across nanostructured interfaces. We observe the transition from a diffusive to a ballistic thermal transport regime, with a corresponding increase in the interface resistivity for line widths smaller than the phonon mean free path in the substrate. Resistivities more than three times higher than the bulk value are measured for the smallest line widths of 65 nm. Our findings are relevant to the modeling and design of heat transport in nanoscale engineered systems, including nanoelectronics, photovoltaics and thermoelectric devices.

Siemens, M.; Li, Q.; Yang, R.; Nelson, K.; Anderson, E.; Murnane, M.; Kapteyn, H.

2009-03-02

255

Advanced Transport Delay Compensation Algorithms: Results of Delay Measurement and Piloted Performance Tests  

NASA Technical Reports Server (NTRS)

This report summarizes the results of delay measurement and piloted performance tests that were conducted to assess the effectiveness of the adaptive compensator and the state space compensator for alleviating the phase distortion of transport delay in the visual system in the VMS at the NASA Langley Research Center. Piloted simulation tests were conducted to assess the effectiveness of two novel compensators in comparison to the McFarland predictor and the baseline system with no compensation. Thirteen pilots with heterogeneous flight experience executed straight-in and offset approaches, at various delay configurations, on a flight simulator where different predictors were applied to compensate for transport delay. The glideslope and touchdown errors, power spectral density of the pilot control inputs, NASA Task Load Index, and Cooper-Harper rating of the handling qualities were employed for the analyses. The overall analyses show that the adaptive predictor results in slightly poorer compensation for short added delay (up to 48 ms) and better compensation for long added delay (up to 192 ms) than the McFarland compensator. The analyses also show that the state space predictor is fairly superior for short delay and significantly superior for long delay than the McFarland compensator.

Guo, Liwen; Cardullo, Frank M.; Kelly, Lon C.

2007-01-01

256

The basic reproductive number of Ebola and the effects of public health measures: the cases of Congo and Uganda  

Microsoft Academic Search

Despite improved control measures, Ebola remains a serious public health risk in African regions where recurrent outbreaks have been observed since the initial epidemic in 1976. Using epidemic modeling and data from two well-documented Ebola outbreaks (Congo 1995 and Uganda 2000), we estimate the number of secondary cases generated by an index case in the absence of control interventions R0.

Gerardo Chowell; Nick W. Hengartner; Carlos Castillo-Chavez; Paul W. Fenimore; J. M. Hyman

2004-01-01

257

Power of Latent Growth Modeling for Detecting Linear Growth: Number of Measurements and Comparison with Other Analytic Approaches  

ERIC Educational Resources Information Center

The authors investigated 2 issues concerning the power of latent growth modeling (LGM) in detecting linear growth: the effect of the number of repeated measurements on LGM's power in detecting linear growth and the comparison between LGM and some other approaches in terms of power for detecting linear growth. A Monte Carlo simulation design was…

Fan, Xitao; Fan, Xiaotao

2005-01-01

258

Measurement of effective atomic number and electron density using an EMI scanner  

Microsoft Academic Search

Computed tomography, employing an EMI scanner at two beam energies, can be used to obtain information about the electron density and the effective atomic number of materials. The theory which is discussed has been verified experimentally and then applied in the investigation of some brain tumours in vivo. It is anticipated that, as techniques improve, the ability to carry out

R. A. Rutherford; B. R. Pullan; I. Isherwood

1976-01-01

259

Long range atmospheric transport of Aerosols: First ARCTIC measurements using Quadrupole Aerosol Mass Spectrometer  

NASA Astrophysics Data System (ADS)

Atmospheric aerosols can directly affect climate by scattering and absorbing solar radiation, thereby modifying the radiative balance of the atmosphere. Aerosols can also act as cloud condensation nuclei, which alter cloud properties and precipitation rates, thereby indirectly influencing the climate. Aerosol surfaces are a medium for heterogeneous reactions and carry many different compounds, which naturally affect their properties. Since aerosol lifetimes in the troposphere are on the order of days to a week, they are transported throughout the atmosphere. To study this transport, we installed a Q - AMS in the Polar Environment Atmospheric Research Laboratory in August 2006. The laboratory is located on Ellesmere Island, (80°N 86°W at 610 m above sea level). It provides a unique location for observing transport to the sensitive Arctic ecosystem because it is far from anthropogenic sources of contamination. In this presentation, we will report the analysis of aerosol mass concentrations, size, and chemical compositions covering the time period from August, 2006 to May 2009. Our measurements show that sulphate dominates the aerosol composition most of the time, with a maximum concentration of 0.655 µg/m3 and minimum concentration of 0.030 µg/m3. The second most abundant species was organic aerosols, with concentrations in the range from 0.440 µg/m3 to 0.050 µg/m3. Although the sulphate dominates in general, plots of concentration time series show a seasonal change in the relative concentrations of sulphate and organic species. Relatively lower concentrations of nitrate and ammonium species were detected during the period of our observations. Occasional episodes of concentrations up to 0.050 µg/m3 nitrate and 0.080 µg/m3 ammonium were detected; otherwise these were below our detection limit (0.009 µg/m3). In addition to the above results, we will briefly report the ionic components and discuss possible aerosol transportation routes determined with the semi-Lagrangian trajectory model, FLEXPART.

Bacak, A.; Damoah, R.; Sloan, J.

2009-05-01

260

Electrical transport measurements on polycrystalline superconducting Y-Ba-Cu-O films  

NASA Technical Reports Server (NTRS)

The current-voltage, I-V, characteristics of polycrystalline Y-Ba-Cu-O films have been measured as a function of temperature. The I-V characteristics are interpreted using a model based upon an array of weak links with a statistical distribution of critical currents. In addition, evidence is found that the supercurrents flow in nearly independent filaments near Tc. Various criteria are discussed with respect to the definition of the transport critical current, Ic, in these films. A temperature dependence for Ic has also been deduced from the I-V data by appealing to an empirical scaling law. It is proposed that this temperature dependence is representative of the weaker links within the critical current distribution.

Stan, M. A.; Alterovitz, S. A.; Ignjatovic, D.

1990-01-01

261

Joint measurement of photon-number sum and phase-difference operators in a two-mode field  

SciTech Connect

We present an experimental scheme that realizes joint measurement of photon-number sum and phase-difference operators on a two-mode field. The proposed scheme only involves linear optical elements and photon detectors with single-photon sensitivity. Furthermore, we demonstrate that such a measurement setup can be applied to generate two-mode N-photon entangled states from a pair of squeezed vacuum states. These N-photon entangled states are useful resources for quantum-information processing, high-precision frequency measurement, and quantum optical lithography.

Zou Xubo; Pahlke, K.; Mathis, W. [Electromagnetic Theory Group at THT, Department of Electrical Engineering, University of Hannover, D-30167 Hannover (Germany)

2003-10-01

262

Continuous non-contact measurement of electric charges of solid particles in pipes of pneumatic transport. II. Measuring system and its application  

Microsoft Academic Search

For pt.I see ibid., vol.2, p.1958-63, 1989. A measuring system that enables the electric charges of solid particles in a pneumatic-transport pipe to be conveniently, precisely, reliably, and quickly measured is described. The system is made up of a measuring head comprising a sensing element (metal inductive ring probe), a parallel-to-input capacitor of a high capacitance value, and a preamplifier;

Juliusz B. Gajewski; B. Glod; Ryszard A. Grobelny; W. Kala

1989-01-01

263

Measurement of Fracture Aperture Fields Using Ttransmitted Light: An Evaluation of Measurement Errors and their Influence on Simulations of Flow and Transport through a Single Fracture  

SciTech Connect

Understanding of single and multi-phase flow and transport in fractures can be greatly enhanced through experimentation in transparent systems (analogs or replicas) where light transmission techniques yield quantitative measurements of aperture, solute concentration, and phase saturation fields. Here we quanti@ aperture field measurement error and demonstrate the influence of this error on the results of flow and transport simulations (hypothesized experimental results) through saturated and partially saturated fractures. find that precision and accuracy can be balanced to greatly improve the technique and We present a measurement protocol to obtain a minimum error field. Simulation results show an increased sensitivity to error as we move from flow to transport and from saturated to partially saturated conditions. Significant sensitivity under partially saturated conditions results in differences in channeling and multiple-peaked breakthrough curves. These results emphasize the critical importance of defining and minimizing error for studies of flow and transpoti in single fractures.

Detwiler, Russell L.; Glass, Robert J.; Pringle, Scott E.

1999-05-06

264

Lagrangian Transport Model Forecasts as Useful Support of the Flight Planning During the Intercontinental Transport and Chemical Transformation 2002 (ITCT 2k2) Measurement Campaign  

NASA Astrophysics Data System (ADS)

In this study, the Lagrangian tracer transport model FLEXPART is shown to be a useful forecasting tool for the flight planning during the ITCT 2k2 (Intercontinental Transport and Chemical Transformation 2002) aircraft measurement campaign. The advantages of this model are that it requires only a short computation time, has a finer spatial resolution and does not suffer numerical diffusion compared to chemistry transport models (CTMs). It is a compromise between simple trajectory calculations and complex CTMs that makes best use of available computer hardware. During the campaign FLEXPART provided three-day forecasts for four different anthropogenic CO tracers: Asian, North American, Japanese, and European. The forecasts were based on data from the Aviation model (AVN) of the National Center for Environmental Prediction (NCEP) and relied on the EDGAR emission inventory for the base year 1990. In two case studies, the forecast abilities of FLEXPART are analysed and discussed by comparing the forecasts with measurement data, results from the post analysis modelling, infrared satellite images, and backward trajectories calculated with two different Lagrangian trajectory models. It is shown that intercontinental transport and dispersion of pollution plumes were qualitatively well predicted, and the aircraft could successfully be directed into the polluted air masses.

Forster, C.; Cooper, O.; Stohl, A.; Eckhardt, S.; James, P.; Dunlea, E.; Nicks, D. K.; Holloway, J. S.; Hübler, G.; Parrish, D. D.; Ryerson, T. B.; Trainer, M.

2002-12-01

265

Photosynthetic electron transport in an anoxygenic photosynthetic bacterium Afifella (Rhodopseudomonas) marina measured using PAM fluorometry.  

PubMed

Blue diode-based pulse amplitude modulation (PAM) technology can be used to measure the photosynthetic electron transport rate (ETR) in a purple nonsulfur anoxygenic photobacterium, Afifella (Rhodopseudomonas) marina. Rhodopseudomonads have a reaction center light harvesting antenna complex containing an RC-2 type bacteriochlorophyll a protein (BChl a RC-2-LH1) which has a blue absorption peak and variable fluorescence similar to PSII. Absorptance of cells filtered onto glass fiber disks was measured using a blue-diode-based absorptance meter (Blue-RAT) so that absolute ETR could be calculated from PAM experiments. Maximum quantum yield (Y) was ?0.6, decreasing exponentially as irradiance increased. ETR vs irradiance (P vs E) curves fitted the waiting-in-line model (ETR = (ETRmax  × E/Eopt ) × exp(1 - E/Eopt )). Maximum ETR (ETRmax ) was ?1000-2000 ?mol e(-)  mg(-1)  BChl a h(-1) . Fe(2+) , bisulfite and thiosulfate act as photosynthetic electron donors. Optimum irradiance was ?100 ?mol m(-2)  s(-1) PPFD even in Afifella grown in sunlight. Quantum efficiencies (?) were ?0.3-0.4 mol e(-)  mol h?(-1) ; or ?11.8 ± 2.9 mol e(-)  mol h?(-1)  m(2)  ?g(-1)  BChl a). An underlying layer of Afifella in a constructed algal/photosynthetic bacterial mat has little effect on the measured ETR of the overlying oxyphotoautotroph (Chlorella). PMID:22978665

Ritchie, Raymond J; Runcie, John W

2013-01-01

266

Earth strain measurements with the transportable laser ranging system: Field techniques and planning  

NASA Technical Reports Server (NTRS)

The potential of the transportable laser ranging system for monitoring the ground deformation around satellite ranging stations and other geodetic control points was examined with emphasis on testing the usefulness of the relative alteration technique. The temporal variation of the ratio of the length of each survey line to the mean length of all survey lines in a given area is directly related to the mean shear strain rate for the area. The data from a series of experimental measurements taken over the Los Angeles basin from a TLRS station at Mt. Wilson show that such ratios can be determined to an accuracy of one part in 10 million with a measurement program lasting for three days and without using any corrections for variations in atmospheric conditions. A numerical experiment using a set of hypothetical data indicates that reasonable estimates of the present shear strain rate and the direction of the principal axes in southern California can be deduced from such measurements over an interval of one to two years.

Nakamura, Y.; Dorman, H. J.; Cahill, T.

1982-01-01

267

Dynamic measurements of thermal transport coefficients and boundary resistance I. Normal {sup 4}He  

SciTech Connect

The thermal conductivity, {kappa}, and the thermal diffusivity, D{sub T}, of normal liquid {sup 4}He have been obtained from the temperature response, {Delta}T ({omega}), across a fluid layer of thickness, d, to an ac heat flux, Q(t) = Q{sub o}exp(i{omega}t). Previous transient heat flux experiments measured the thermal relaxation of the fluid towards equilibrium and assumed the dominance of a single slowest mode. The present ac technique allows measurements under steady-state conditions while driving the system at a single frequency, {omega}. The response curve for {Delta}T({omega})/Q{sub o} yields data for {kappa}, D{sub T} and the boundary resistance, R{sub b}. Boundary effects appear at frequencies higher than {tau}{sup {minus}1}{triple_bond} D{sub T}/d{sup 2} where the fluid is unresponsive to bulk heat transport. The authors use this fact to obtain R{sub b} with high accuracy in the normal phase from the high frequency response. In addition, the apparatus permits the fluid thickness, d, to be varied continuously and in situ from zero to 3 mm, allowing for further consistency in the fluid measurements. This work also includes data for the onset of convection where Q{sub o}>Q{sub c}, and Q{sub c} corresponds to the heat amplitude at convective onset.

Olafsen, J.S.; Behringer, R.P. [Duke Univ., Durham, NC (United States)

1997-03-01

268

Measuring acuity of the approximate number system reliably and validly: the evaluation of an adaptive test procedure  

PubMed Central

Two studies investigated the reliability and predictive validity of commonly used measures and models of Approximate Number System acuity (ANS). Study 1 investigated reliability by both an empirical approach and a simulation of maximum obtainable reliability under ideal conditions. Results showed that common measures of the Weber fraction (w) are reliable only when using a substantial number of trials, even under ideal conditions. Study 2 compared different purported measures of ANS acuity as for convergent and predictive validity in a within-subjects design and evaluated an adaptive test using the ZEST algorithm. Results showed that the adaptive measure can reduce the number of trials needed to reach acceptable reliability. Only direct tests with non-symbolic numerosity discriminations of stimuli presented simultaneously were related to arithmetic fluency. This correlation remained when controlling for general cognitive ability and perceptual speed. Further, the purported indirect measure of ANS acuity in terms of the Numeric Distance Effect (NDE) was not reliable and showed no sign of predictive validity. The non-symbolic NDE for reaction time was significantly related to direct w estimates in a direction contrary to the expected. Easier stimuli were found to be more reliable, but only harder (7:8 ratio) stimuli contributed to predictive validity. PMID:23964256

Lindskog, Marcus; Winman, Anders; Juslin, Peter; Poom, Leo

2013-01-01

269

Measure a picture, number 1 : inch, half, quarter of an inch  

NSDL National Science Digital Library

This resource is the first of 5 worksheets on reading a measurement ruler. The Step-by-Step handout allows the learner to practice drawing and identifying measurements by inch, quarter, and half of an inch. Each completed tasks will be indicated by the check placed in the boxes by the learners. In this activity, there are 21 tasks to check off and 1 question to answer. Copyright 2005 International Technology Education Association

Louisiana Technology Student Association (LTSA); Louisiana Technology Educator's Association (LTEA)

2003-01-01

270

Bias and uncertainty in emission absorption measurements of temperature and atomic number density  

Microsoft Academic Search

Presented here is an analysis of the bias and uncertainty arising from two major, and usually unavoidable, problems in applying emission absorption diagnostic methods to large-scale combustion systems: (1) keeping the windows clean and (2) maintaining the optical alignment. The impetus for the study was an anomalously large temperatrue measurement uncertainty for potassium D-line measurements in a coal-fired magnetohydrodynamic flow.

Leslie E. Bauman

1991-01-01

271

Improvement of storage, handling, and transportability of fine coal. Quarterly technical progress report number 8, October 1--December 31, 1995  

SciTech Connect

The Mulled Coal process was developed as a means of overcoming the adverse handling characteristics of wet fine coal without thermal drying. The process involves the addition of a low cost, harmless reagent to wet fine coal using off-the-shelf mixing equipment. Based on laboratory- and bench-scale testing, Mulled coal can be stored, shipped, and burned without causing any of the plugging, pasting, carryback and freezing problems normally associated with wet coal. On the other hand, Mulled Coal does not cause the fugitive and airborne dust problems normally associated with thermally dried coal. The objectives of this project are to demonstrate that: the Mulled Coal process, which has been proved to work on a wide range of wet fine coals at bench scale, will work equally well on a continuous basis, producing consistent quality, and at a convincing rate of production in a commercial coal preparation plant; the wet product from a fine coal cleaning circuit can be converted to a solid fuel form for ease of handling and cost savings in storage and rail car transportation; and a wet fine coal product thus converted to a solid fuel form, can be stored, shipped, and burned with conventional fuel handling, transportation, and combustion systems.

NONE

1996-03-15

272

Flowfield measurements about a multi-element airfoil at high Reynolds numbers  

NASA Technical Reports Server (NTRS)

This paper describes experimental data obtained with a multi-element airfoil at flight Reynolds numbers and lift coefficients including Clmax. The wind tunnel test was conducted in the NASA Langley Low Turbulence Pressure Tunnel as part of a cooperative effort between McDonnell Douglas Aerospace and NASA Langley. The airfoil model is a supercritical design configured with a leading-edge slat and a single-segment trailing-edge flap. Data include surface static-pressure distributions (integrated to obtain lift), drag data obtained with wake-rake surveys, and fbwfield surveys obtained with a flat-tube and five-hole probe at nine stations on the configuration's upper surface. Effects of variations in Reynolds number and flap gap on airfoil performance and flowfield survey data are presented.

Chin, Vincent D.; Peters, David W.; Spaid, Frank W.; Mcghee, Robert J.

1993-01-01

273

Phase Averaged Measurements of the Coherent Structure of a Mach Number 0.6 Jet. M.S. Thesis  

NASA Technical Reports Server (NTRS)

The existence of a large scale structure in a Mach number 0.6, axisymmetric jet of cold air was proven. In order to further characterize the coherent structure, phase averaged measurements of the axial mass velocity, radial velocity, and the product of the two were made. These measurements yield information about the percent of the total fluctuations contained in the coherent structure. These measured values were compared to the total fluctuation levels for each quantity and the result expressed as a percent of the total fluctuation level contained in the organized structure at a given frequency. These measurements were performed for five frequencies (St=0.16, 0.32, 0.474, 0.95, and 1.26). All of the phase averaged measurements required that the jet be artificially excited.

Emami, S.

1983-01-01

274

Household transport expenditure in Sub-Saharan African cities: measurement and analysis  

Microsoft Academic Search

In Sub-Saharan Africa the cost of transport faced by city dwellers, particularly the poor, tends to add to their travel and economic difficulties. Knowledge of the burden of transport expenditure in the household budget seems essential for passenger transport policy formulation in order to improve their travel conditions and social equity.The literature review and the three case studies (Dar es

Lourdes Diaz-Olvera; Didier Plat; Pascal Pochet

2008-01-01

275

Determination of car on-road black carbon and particle number emission factors and comparison between mobile and stationary measurements  

NASA Astrophysics Data System (ADS)

We have used two methods for measuring emission factors (EFs) in real driving conditions on five cars in a controlled environment: the stationary method, where the investigated vehicle drives by the stationary measurement platform and the composition of the plume is measured, and the chasing method, where a mobile measurement platform drives behind the investigated vehicle. We measured EFs of black carbon and particle number concentration. The stationary method was tested for repeatability at different speeds and on a slope. The chasing method was tested on a test track and compared to the portable emission measurement system. We further developed the data processing algorithm for both methods, trying to improve consistency, determine the plume duration, limit the background influence and facilitate automatic processing of measurements. The comparison of emission factors determined by the two methods showed good agreement. EFs of a single car measured with either method have a specific distribution with a characteristic value and a long tail of super emissions. Measuring EFs at different speeds or slopes did not significantly influence the EFs of different cars; hence, we propose a new description of vehicle emissions that is not related to kinematic or engine parameters, and we rather describe the vehicle EF with a characteristic value and a super emission tail.

Ježek, I.; Drinovec, L.; Ferrero, L.; Carriero, M.; Mo?nik, G.

2015-01-01

276

Determination of car on-road black carbon and particle number emission factors and comparison between mobile and stationary measurements  

NASA Astrophysics Data System (ADS)

We have used two methods for measuring emission factors (EF) in real driving conditions on five cars in a controlled environment: the stationary method, where the investigated vehicle drives by the stationary measurement platform and the composition of the plume is measured; and the chasing method, where a mobile measurement platform drives behind the investigated vehicle. We measured EF of black carbon and particle number concentration. The stationary method was tested for repeatability at different speeds and on a slope. The chasing method was tested on a test track and compared to the portable emission measurement system. We further developed the data processing algorithm for both methods, trying to improve consistency, determine the plume duration, limit the background influence and facilitate automatic processing of measurements. The comparison of emission factors determined by the two methods showed good agreement. EFs of a single car measured with either method have a specific distribution with a characteristic value and a long tail of super emissions. Measuring EFs at different speeds or slopes did not significantly influence the EFs of different cars, hence we propose a new description of vehicle emissions that is not related to kinematic or engine parameters, rather we describe the vehicle EF with a characteristic value and a "super emission" tail.

Ježek, I.; Drinovec, L.; Ferrero, L.; Carriero, M.; Mo?nik, G.

2014-06-01

277

Correlated biofilm imaging, transport and metabolism measurements via combined nuclear magnetic resonance and confocal microscopy.  

PubMed

Bacterial biofilms are complex, three-dimensional communities found nearly everywhere in nature and are also associated with many human diseases. Detailed metabolic information is critical to understand and exploit beneficial biofilms as well as combat antibiotic-resistant, disease-associated forms. However, most current techniques used to measure temporal and spatial metabolite profiles in these delicate structures are invasive or destructive. Here, we describe imaging, transport and metabolite measurement methods and their correlation for live, non-invasive monitoring of biofilm processes. This novel combination of measurements is enabled by the use of an integrated nuclear magnetic resonance (NMR) and confocal laser scanning microscope (CLSM). NMR methods provide macroscopic structure, metabolic pathway and rate data, spatially resolved metabolite concentrations and water diffusion profiles within the biofilm. In particular, current depth-resolved spectroscopy methods are applied to detect metabolites in 140-190 nl volumes within biofilms of the dissimilatory metal-reducing bacterium Shewanella oneidensis strain MR-1 and the oral bacterium implicated in caries disease, Streptococcus mutans strain UA159. The perfused sample chamber also contains a transparent optical window allowing for the collection of complementary fluorescence information using a unique, in-magnet CLSM. In this example, the entire three-dimensional biofilm structure was imaged using magnetic resonance imaging. This was then correlated to a fluorescent CLSM image by employing a green fluorescent protein reporter construct of S. oneidensis. Non-invasive techniques such as described here, which enable measurements of dynamic metabolic processes, especially in a depth-resolved fashion, are expected to advance our understanding of processes occurring within biofilm communities. PMID:18253132

McLean, Jeffrey S; Ona, Ositadinma N; Majors, Paul D

2008-02-01

278

In conventional database systems, performance is pri marily measured by the number of transactions com  

E-print Network

measures. There have been performance studies on real­time data­ base systems, but most of them were performed using simulation. This work demonstrates the feasibility of developing a real­time database system of collect­ ing, storing, and retrieving data in real­time by devising database management systems to manage

Son, Sang H.

279

VOLUME 15, NUMBER 2, 2005 LINCOLN LABORATORY JOURNAL New Measures of Effectiveness for Human Language Technology  

E-print Network

by the Defense Advanced Research Projects Agency and the Defense Language Institute under Air Force Contract FA project involving Lincoln Laboratory, the MIT Department of Brain and Cognitive Sciences, and the Defense for Human Language Technology New Measures of Effectiveness for Human Language Technology n Research

280

Daytime Image Measurement and Reconstruction for Space Situational Awareness Applications (Paper ID number 4231324)  

Microsoft Academic Search

An operational technology for imaging satellites during the daytime hours would vastly increase the ability of optical space situational awareness (SSA) systems to gather information about satellites. During the day the atmospheric seeing is generally worse than in terminator, and the contribution of sky background noise to the image measurement is significant. We have developed a straightforward model for estimating

M. Roggemann; D. Douglas; E. Therkildsen; D. Archambeault; R. Maeda; D. Schultz; B. Wheeler

2010-01-01

281

PHYSICAL REVIEW A VOLUME 51, NUMBER 2 FEBRUARY 1995 Dynamics of quantum collapse in energy measurements  

E-print Network

measurements Ubaldo Tambini Dipartimento di Fisica, Universita di Ferrara, and Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara, Vha ParaChao 12, Ferrara, Italy $/100 Carlo Presilla Dipartimento di Fisica, Universita di Roma "La Sapienza, "and Istituto Nazionale di Fisica Nucleare, Sezione di Roma, Piazzale A

Presilla, Carlo

282

aeroacoustics volume 9 number 3 2010 pages 329355 329 Measurements and wall modeled LES  

E-print Network

simulation of trailing edge noise caused by a turbulent boundary layer Björn Greschner1, J. Grilliat2, M-CAA and measurements of trailing edge noise is shown for a highly loaded and cambered NACA 5510 airfoil at a chord with the trailing edge generate significant broadband noise in the far field. The IDDES approach is designed

Paris-Sud XI, Université de

283

Measuring and modeling of a three-dimensional tracer transport in a planted soil column  

NASA Astrophysics Data System (ADS)

Water flow from soil to root is driven by the plant transpiration and an important component of the hydrological cycle. The model R-SWMS combines three-dimensional (3D) water flow and solute transport in soil with a detailed description of root structure in three dimensions [1,2]. This model offers the possibility to calculate root water and solute uptake and flow within the roots, which enables explicit studies with respect to the distribution of water and solutes around the roots as well as local processes at the root-soil interface. In this study, we compared measured data from a tracer experiment using Magnetic Resonance Imaging (MRI) with simulations in order to assess the distribution and magnitude of the water uptake of a young lupine plant. An aqueous solution of the Gadolinium-complex (Gd-DTPA2-) was chosen as a tracer, as it behaves conservatively and is ideally suited for MRI. Water flow in the soil towards the roots can thus be visualized by following the change in tracer concentrations over time. The data were obtained by MRI, providing high resolution 3D images of the tracer distribution and root architecture structures by using a spin echo pulse sequence, which is strongly T1- weighted to be tracer sensitive [3], and T2 -weighted for root imaging [4]. This experimental setup was simulated using the 3D high-resolution numerical model R-SWMS. The comparison between MRI data and the simulations showed extensive effects of root architecture parameters on solute spreading. Although the results of our study showed the strength of combining non-invasive measurements and 3D modeling of solute and water flow in soil-root systems, where the derivation of plant hydraulic parameters such as axial and radial root conductivities is possible, current limitations were found with respect to MRI measurements and process description. [1] Javaux, M., T. Schröder, J. Vanderborght, and H. Vereecken (2008), Use of a Three-Dimensional Detailed Modeling Approach for Predicting Root Water Uptake, Vadose Zone Journal, 7(3), 1079-1079. [2] Schröder, N., M. Javaux, J. Vanderborght, B. Steffen, and H. Vereecken (2012), Effect of Root Water and Solute Uptake on Apparent Soil Dispersivity: A Simulation Study, Vadose Zone Journal, 11(3). [3 ]Haber-Pohlmeier, S., Bechtold, M., Stapf, S., and Pohlmeier, A. (2010). Water Flow Monitored by Tracer Transport in Natural Porous Media Using Magnetic Resonance Imaging. Vadose Zone Journal (9),835-845. [4] Stingaciu, L. R., Schulz, H., Pohlmeier, A., Behnke, S., Zilken, H., Vereecken, H., and Javaux, M. (2013). In Situ Root System Architecture Extraction from Magnetic Resonance Imaging for Application to Water Uptake Modeling. Vadose Zone Journal.

Schroeder, N.; Javaux, M.; Haber-Pohlmeier, S.; Pohlmeier, A. J.; Huber, K.; Vereecken, H.; Vanderborght, J.

2013-12-01

284

Measurements of dynamo electric field and momentum transport induced by fluctuations on HIST  

NASA Astrophysics Data System (ADS)

Coaxial Helicity injection (CHI) is an efficient current-drive method used in spheromak and spherical torus (ST) experiments. It is an important issue to investigate dynamo effect to explore CHI current drive mechanisms. To establish the dynamo model with two-fluid Hall effects, we verify the parallel mean-field Ohm's law balance. The spatial profiles of the MHD/Hall dynamo electric fields are measured by using Mach probe and Hall probe involving 3-axis magnetic pick-up coils. The MHD/Hall fluctuation-induced electromotive forces are large enough to sustain the mean toroidal current against the resistive decay. We have measured the electron temperature and the density with great accuracy by using a new electrostatic probe with voltage sweeping. The result shows that the electron temperature is high in the core region and low in the central open flux column (OFC), and the electron density is highest in the OFC region. The Hall dynamo becomes more dominant in a lower density region compared to the MHD dynamo. In addition, the fluctuation-induced Maxwell and Reynolds stresses are calculated to examine the fast radial transport of momentum from the OFC to the core region during the dynamo drive.

Hirono, H.; Hanao, T.; Hyobu, T.; Ito, K.; Matsumoto, K.; Nakayama, T.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

2012-10-01

285

Kelvin probe microscopy and electronic transport measurements in reduced graphene oxide chemical sensors.  

PubMed

Reduced graphene oxide (RGO) is an electronically hybrid material that displays remarkable chemical sensing properties. Here, we present a quantitative analysis of the chemical gating effects in RGO-based chemical sensors. The gas sensing devices are patterned in a field-effect transistor geometry, by dielectrophoretic assembly of RGO platelets between gold electrodes deposited on SiO2/Si substrates. We show that these sensors display highly selective and reversible responses to the measured analytes, as well as fast response and recovery times (tens of seconds). We use combined electronic transport/Kelvin probe microscopy measurements to quantify the amount of charge transferred to RGO due to chemical doping when the device is exposed to electron-acceptor (acetone) and electron-donor (ammonia) analytes. We demonstrate that this method allows us to obtain high-resolution maps of the surface potential and local charge distribution both before and after chemical doping, to identify local gate-susceptible areas on the RGO surface, and to directly extract the contact resistance between the RGO and the metallic electrodes. The method presented is general, suggesting that these results have important implications for building graphene and other nanomaterial-based chemical sensors. PMID:23703020

Kehayias, Christopher E; MacNaughton, Samuel; Sonkusale, Sameer; Staii, Cristian

2013-06-21

286

In-situ Resistive Measurements of Graphite Oxide Reduction for Spin-Transport Based Devices  

NASA Astrophysics Data System (ADS)

In this work, the thermal reduction to graphene of single and few-layer graphite oxide (GO) was characterized as a function of time using in-situ, four-point resistivity measurements. GO was produced chemically using a modified Hummer's method and then spray deposited onto an oxidized Si wafer. 100 nm Au with a 5 nm Cr adhesion layer was thermally evaporated onto the randomly dispersed GO, and then defined lithographically into an array of four point probe contact structures. High-temperature probes were used to make contact with the samples in a furnace tube where the GO was heated to 300 C for 30 minutes under forming gas atmosphere (90% N2/10% H2). The measured conductance increased several orders of magnitude as the insulating properties of GO transitioned to the semi-metallic properties of graphene. Graphene and GO were further characterized before and after thermal reduction using atomic force microscopy (AFM) and Raman spectroscopy. We also report on similar experiments using ferromagnetic CoFe contacts for spin-dependent transport experiments.

Jewell, Ira; Huang, Chien-Chih; Smith, Sean; Mason, Ashley; Jander, Albrecht; Conley, John

2010-03-01

287

Kelvin probe microscopy and electronic transport measurements in reduced graphene oxide chemical sensors  

NASA Astrophysics Data System (ADS)

Reduced graphene oxide (RGO) is an electronically hybrid material that displays remarkable chemical sensing properties. Here, we present a quantitative analysis of the chemical gating effects in RGO-based chemical sensors. The gas sensing devices are patterned in a field-effect transistor geometry, by dielectrophoretic assembly of RGO platelets between gold electrodes deposited on SiO2/Si substrates. We show that these sensors display highly selective and reversible responses to the measured analytes, as well as fast response and recovery times (tens of seconds). We use combined electronic transport/Kelvin probe microscopy measurements to quantify the amount of charge transferred to RGO due to chemical doping when the device is exposed to electron-acceptor (acetone) and electron-donor (ammonia) analytes. We demonstrate that this method allows us to obtain high-resolution maps of the surface potential and local charge distribution both before and after chemical doping, to identify local gate-susceptible areas on the RGO surface, and to directly extract the contact resistance between the RGO and the metallic electrodes. The method presented is general, suggesting that these results have important implications for building graphene and other nanomaterial-based chemical sensors.

Kehayias, Christopher E.; MacNaughton, Samuel; Sonkusale, Sameer; Staii, Cristian

2013-06-01

288

New gauge fields from extension of space time parallel transport of vector spaces to the underlying number systems.  

SciTech Connect

One way of describing gauge theories in physics is to assign a vector space {bar V}{sub x} to each space time point x. For each x the field {psi} takes values {psi}(x) in {bar V}{sub x}. The freedom to choose a basis in each {bar V}{sub x} introduces gauge group operators and their Lie algebra representations to define parallel transformations between vector spaces. This paper is an exploration of the extension of these ideas to include the underlying scalar complex number fields. Here a Hilbert space, {bar H}{sub x}, as an example of {bar V}{sub x}, and a complex number field, {bar C}{sub x}, are associated with each space time point. The freedom to choose a basis in {bar H}{sub x} is expanded to include the freedom to choose complex number fields. This expansion is based on the discovery that there exist representations of complex (and other) number systems that differ by arbitrary scale factors. Compensating changes must be made in the basic field operations so that the relevant axioms are satisfied. This results in the presence of a new real valued gauge field A(x). Inclusion of A(x) into covariant derivatives in Lagrangians results in the description of A(x) as a gauge boson for which mass is optional. The great accuracy of QED suggests that the coupling constant of A(x) to matter fields is very small compared to the fine structure constant. Other physical properties of A(x) are not known at present.

Benioff, P. (Physics)

2011-06-01

289

Application of acoustic doppler current profilers for measuring three-dimensional flow fields and as a surrogate measurement of bedload transport  

USGS Publications Warehouse

Acoustic Doppler current profilers (ADCPs) have been in use in the riverine environment for nearly 20 years. Their application primarily has been focused on the measurement of streamflow discharge. ADCPs emit high-frequency sound pulses and receive reflected sound echoes from sediment particles in the water column. The Doppler shift between transmitted and return signals is resolved into a velocity component that is measured in three dimensions by simultaneously transmitting four independent acoustical pulses. To measure the absolute velocity magnitude and direction in the water column, the velocity magnitude and direction of the instrument must also be computed. Typically this is accomplished by ensonifying the streambed with an acoustical pulse that also provides a depth measurement for each of the four acoustic beams. Sediment transport on or near the streambed will bias these measurements and requires external positioning such as a differentially corrected Global Positioning Systems (GPS). Although the influence of hydraulic structures such as spur dikes and bridge piers is typically only measured and described in one or two dimensions, the use of differentially corrected GPS with ADCPs provides a fully three-dimensional measurement of the magnitude and direction of the water column at such structures. The measurement of these flow disturbances in a field setting also captures the natural pulsations of river flow that cannot be easily quantified or modeled by numerical simulations or flumes. Several examples of measured three-dimensional flow conditions at bridge sites throughout Alaska are presented. The bias introduced to the bottom-track measurement is being investigated as a surrogate measurement of bedload transport. By fixing the position of the ADCP for a known period of time the apparent velocity of the streambed at that position can be determined. Initial results and comparison to traditionally measured bedload values are presented. These initial results and those by other researchers are helping to determine a direction for further research of noncontact measurements of sediment transport. Copyright ASCE 2005.

Conaway, J.S.

2005-01-01

290

Integration of field measurements and reactive transport modelling to evaluate contaminant transport at a sulfide mine tailings impoundment.  

PubMed

Over a decade of field observations including geochemical, mineralogical and hydrological information are available on the generation of acid mine drainage from the Pistol Dam region of the P-area of Inco's tailings impoundment in Copper Cliff, Ontario. This work focuses on the integration and quantitative assessment of this data set using reactive transport modeling. The results of the reactive transport simulations are in general agreement with the field observations; however, exact agreement between the field and simulated results was not the objective of this study, and was not attained. Many factors contribute to the discrepancies between the field observations and simulation results including geochemical and hydrogeological complexities and necessary model simplifications. For example, fluctuating water levels observed at the site were averaged and described using a steady state flow system. In addition, the lack of representative thermodynamic and rate expression data contributed to the discrepancies between observations and simulation results, thus further research into the applicability of laboratory-derived thermodynamic and rate expression data to field conditions could minimize these discrepancies. Despite the discrepancies between the field observations and simulated results, integrating field observations with numerical modelling of the P-area tailings impoundment allowed for a more complete understanding of what affects the complex geochemical reactions. PMID:16844261

Brookfield, A E; Blowes, D W; Mayer, K U

2006-11-20

291

Measurement of Large-Scale Sediment Transport Dynamics Using Multibeam Sonar  

NASA Astrophysics Data System (ADS)

Multibeam Echo-Sounder (MBES) sonar systems have developed rapidly over recent decades and are now routinely deployed to provide high-resolution object detection and bathymetric surveying in a range of aquatic environments, from the deep-sea to lakes and rivers. MBES systems were developed for bottom-detection and measurement of bed morphology, and have previously discarded the received acoustic back-scatter from the water column after the bottom-detection algorithms have been performed. However, modern data handling and storage technologies have facilitated the logging of this large quantity of acoustic intensity and phase information, and commercial MBES systems are now available that provide this capability. This paper develops a novel methodology to exploit this logging capability to quantify the concentration and dynamics of suspended sediment within the water column. This development provides a multi-purpose tool for the holistic surveying of sediment transport by imaging suspended sediment concentration, associated coherent flow structures and providing concurrent high-resolution bathymetry. This paper presents methods of data analysis and results obtained from deployment of the RESON SeaBat 8125 and 7125 MBES systems in the field and during testing in a controlled environment. The field results were obtained from sites on the Paraná river, Argentina, with the aim of examining the dynamics of suspended sediment transport over dune bedforms and in the region of flow mixing between large rivers of significantly different suspended sediment concentration. Controlled testing was performed in a former ship dry-dock by creating flows density currents of known suspended sediment concentration with different types and mixes of sediment. The results demonstrate the capability of the RESON MBES systems to successfully resolve the contrast in suspended sediment concentration, and hence the spatio-temporal monitoring of the associated coherent flow structures. The results demonstrate the ability of MBES systems to obtain large sets of data across a two-dimensional swath: this enables the real-time monitoring of suspended sediment transport and related flow processes on a scale previously unrealisable with single-beam acoustic back-scatter systems.

Simmons, S. M.; Parsons, D. R.; Best, J. L.; Malzone, C.; Keevil, G.

2007-12-01

292

Resonance lamp absorption measurement of OH number density and temperature in expansion tube scramjet engine tests  

NASA Technical Reports Server (NTRS)

In this paper, we report results of hydroxyl radical and static temperature measurements performed in the General Applied Science Laboratories-NASA HYPULSE expansion tube facility using the microwave resonance lamp absorption technique. Data were obtained as part of a series of hydrogen/air and hydrogen/oxygen combustion tests at stagnation enthalpies corresponding to Mach 17 flight speeds. Data from a representative injector configuration is compared to a full Navier-Stokes CFD solution.

Lempert, Walter R.; Trucco, Richard E.; Bittner, Robert D.

1992-01-01

293

Measurement of atomic number and mass attenuation coefficient in magnesium ferrite  

NASA Astrophysics Data System (ADS)

Pure magnesium ferrite sample was prepared by standard ceramic technique and characterized by X-ray diffraction method. XRD pattern revealed that the sample possess single-phase cubic spinel structure. The linear attenuation coefficient (?), mass attenuation coefficient (?/?), total atomic cross-section (?_{tot}), total electronic cross-section (?_{ele}) and the effective atomic number (Z_{eff}) were calculated for pure magnesium ferrite (MgFe_{2}O_{4}). The values of ?-ray mass attenuation coefficient were obtained using a NaI energy selective scintillation counter with radioactive ?-ray sources having energy 0.36, 0.511, 0.662, 1.17 and 1.28 MeV. The experimentally obtained values of ?/? and Z_{eff} agreed fairly well with those obtained theoretically.

Kadam, R. H.; Alone, S. T.; Bichile, G. K.; Jadhav, K. M.

2007-05-01

294

Comparison of measured and calculated velocity profiles of a laminar incompressible free jet at low Reynolds numbers  

NASA Technical Reports Server (NTRS)

A comparison of the measured and calculated velocity profiles of a laminar, incompressible, low Reynolds number jet is presented. The experimental jet was produced by a nozzle which consists of a porous metal plate covering the end of a pipe. This nozzle produces a uniform exit velocity profile at Reynolds numbers well below those at which conventional contoured nozzles are completely filled by the boundary layer. A jet mixing analysis based on the boundary-layer equations accurately predicted the velocity field for each test condition. The Reynolds number based on nozzle diameter ranged from 50 to 1000 with jet exit velocity either 30 or 61 m/s (100 or 200 ft/sec).

Greene, G. C.

1974-01-01

295

Coincidence measurements between fragment ions and the number of emitted electrons in heavy ion collisions with polyatomic molecules  

NASA Astrophysics Data System (ADS)

We have studied multiple ionization and multifragmentation of a chlorofluorocarbon molecule, CH2FCF3, induced by collisions of 580-keV C+ ions. Coincidence measurements of product ions and the number of emitted electrons from CH2FCF3 were performed under charge-changing conditions of C+ ? Cq+ (q = 0, 2, 3). A fully inclusive measurement regardless of outgoing projectile charge state was also performed by making coincidence with a pulsed ion beam. Mass distributions of fragment ions and number distributions of emitted electrons were both found to change greatly according to charge-changing conditions. Highly multiple ionization emitting up to about 10 electrons was observed in electron loss collisions.

Murai, T.; Majima, T.; Kishimoto, T.; Tsuchida, H.; Itoh, A.

2012-11-01

296

Heat Transfer and Pressure Drop Measurement for Square Channels with V-shape Ribs at High Reynolds Numbers  

E-print Network

gasket to minimize the conduction effect between plates. The ribs are made from copper. The ribs are attached on back and front walls by using copper double sided tape. The top and bottom walls remain smooth. In the Heat transfer experiment, four... HEAT TRANSFER AND PRESSURE DROP MEASUREMENT FOR SQUARE CHANNELS WITH V-SHAPE RIBS AT HIGH REYNOLDS NUMBERS A Thesis by NAWAF YAHYA ALKHAMIS Submitted to the Office of Graduate Studies of Texas A&M University in partial...

Alkhamis, Nawaf Yahya

2010-10-12

297

WIND measurements of proton and alpha particle flow and number density  

NASA Technical Reports Server (NTRS)

We propose to review measurements of the solar wind proton and alpha particle flow velocities and densities made since launch with the WIND SWE instrument. The SWE Faraday cup ion sensors are designed to be able to determine accurately flow vector directions, and thus can be used to detect proton-alpha particle differential flow. Instances of differential flow, and the solar wind features with which they are associated will be discussed. Additionally, the variability of the percentage of alpha particles as a fraction of the total solar wind ion density will be presented.

Steinberg, J. T.; Lazarus, A. J.; Ogilvie, J. T.; Lepping, R.; Byrnes, J.; Chornay, D.; Keller, J.; Torbert, R. B.; Bodet, D.; Needell, G. J.

1995-01-01

298

Direct measurement of the dependence of the photon-number distribution on the number of modes in parametric down-conversion  

E-print Network

Optical parametric down-conversion (PDC) is a central tool in quantum optics experiments. The number of collected down-converted modes greatly affects the quality of the produced photon state. We use Silicon Photomultiplier (SiPM) number-resolving detectors in order to directly observe the photon-number distribution of a PDC source, and show its dependence on the number of collected modes. Additionally, we show how the stimulated emission of photons and the partition of photons into several modes determine the overall photon number. We present a novel analytical model for the optical crosstalk effect in SiPM detectors, and use it to analyze the results.

Dovrat, L; Istrati, D; Shaham, A; Eisenberg, H S

2011-01-01

299

Cryogenic wind tunnel technology. A way to measurement at higher Reynolds numbers  

NASA Technical Reports Server (NTRS)

The goals, design, problems, and value of cryogenic transonic wind tunnels being developed in Europe are discussed. The disadvantages inherent in low-Reynolds-number (Re) wind tunnel simulations of aircraft flight at high Re are reviewed, and the cryogenic tunnel is shown to be the most practical method to achieve high Re. The design proposed for the European Transonic Wind tunnel (ETW) is presented: parameters include cross section. DISPLAY 83A46484/2 = 4 sq m, operating pressure = 5 bar, temperature = 110-120 K, maximum Re = 40 x 10 to the 6th, liquid N2 consumption = 40,000 metric tons/year, and power = 39,5 MW. The smaller Cologne subsonic tunnel being adapted to cryogenic use for preliminary studies is described. Problems of configuration, materials, and liquid N2 evaporation and handling and the research underway to solve them are outlined. The benefits to be gained by the construction of these costly installations are seen more in applied aerodynamics than in basic research in fluid physics. The need for parallel development of both high Re tunnels and computers capable of performing high-Re numerical analysis is stressed.

Beck, J. W.

1984-01-01

300

Visual stimulus parameters seriously compromise the measurement of approximate number system acuity and comparative effects between adults and children  

PubMed Central

It has been suggested that a simple non-symbolic magnitude comparison task is sufficient to measure the acuity of a putative Approximate Number System (ANS). A proposed measure of the ANS, the so-called “internal Weber fraction” (w), would provide a clear measure of ANS acuity. However, ANS studies have never presented adequate evidence that visual stimulus parameters did not compromise measurements of w to such extent that w is actually driven by visual instead of numerical processes. We therefore investigated this question by testing non-symbolic magnitude discrimination in seven-year-old children and adults. We manipulated/controlled visual parameters in a more stringent manner than usual. As a consequence of these controls, in some trials numerical cues correlated positively with number while in others they correlated negatively with number. This congruency effect strongly correlated with w, which means that congruency effects were probably driving effects in w. Consequently, in both adults and children congruency had a major impact on the fit of the model underlying the computation of w. Furthermore, children showed larger congruency effects than adults. This suggests that ANS tasks are seriously compromised by the visual stimulus parameters, which cannot be controlled. Hence, they are not pure measures of the ANS and some putative w or ratio effect differences between children and adults in previous ANS studies may be due to the differential influence of the visual stimulus parameters in children and adults. In addition, because the resolution of congruency effects relies on inhibitory (interference suppression) function, some previous ANS findings were probably influenced by the developmental state of inhibitory processes especially when comparing children with developmental dyscalculia and typically developing children. PMID:23882245

Sz?cs, Dénes; Nobes, Alison; Devine, Amy; Gabriel, Florence C.; Gebuis, Titia

2013-01-01

301

Heat transfer measurements on an incidence-tolerant low pressure turbine blade in a high speed linear cascade at low to moderate Reynolds numbers  

NASA Astrophysics Data System (ADS)

Runway-independent aircraft are expected to be the future for short-haul flights by improving air transportation and reducing area congestion encountered in airports. The Vehicle Systems Program of NASA identified a Large Civil Tilt-Rotor, equipped with variable-speed power-turbine engines, as the best concept. At cruise altitude, the engine rotor-speed will be reduced by as much as the 50% of take-off speed. The large incidence variation in the low pressure turbine associated with the change in speed can be detrimental to the engine performance. Low pressure turbine blades in cruise altitude are more predisposed to develop regions of boundary layer separation. Typical phenomenon such as impinging wakes on downstream blades and mainstream turbulences enhance the complexity of the flow in low pressure turbines. It is therefore important to be able to understand the flow behavior to accurately predict the losses. Research facilities are seldom able to experimentally reproduce low Reynolds numbers at relevant engine Mach number. Having large incidence swing as an additional parameter in the investigation of the boundary layer development, on a low pressure turbine blade, makes this topic unique and as a consequence requires a unique facility to conduct the experimental research. The compressible flow wind tunnel facility at the University of North Dakota had been updated to perform steady state experiments on a modular-cascade, designed to replicate a large variation of the incidence angles. The high speed and low Reynolds number facility maintained a sealed and closed loop configuration for each incidence angle. The updated facility is capable to produce experimental Reynolds numbers as low as 45,000 and as high as 570,000 at an exit Mach number of 0.72. Pressure and surface temperature measurements were performed at these low pressure turbine conditions. The present thesis investigates the boundary layer development on the surface of an Incidence-tolerant blade. The heat transfer approach is the method used to obtain knowledge of the state of the boundary layer on the surface of the blade. Pressure and temperature distributions are acquired for Reynolds numbers of 50,000, 66,000, 228,000, and 568,000 at an exit Mach number of 0.72, and Reynolds numbers of 228,000, and 568,000 at an exit Mach number of 0.35. These experimental flow conditions are conducted at different flow inlet angles of 40°, 34.2°, 28°, 18°, 8°, -2.6°, -12°, and -17°, and at two free-stream turbulence levels. Results of the analyses performed show that as the incidence angle decreases, a region of laminar separation bubble forms on the pressure surface and grows toward the trailing-edge. It is also noted that the position of the leading-edge moves as the incidence angle varies. A transitional flow is observed on both the pressure and suction surfaces, mainly at the two highest incidence angles, for the high turbulence case. This investigation also reveals that the Stanton number increases as the mainstream turbulence increases, and that the Stanton number at the leading-edge increases as the Reynolds number decreases, as it is documented in the literature.

Moualeu, Leolein Patrick Gouemeni

302

Neutron imaging technique for in situ measurement of water transport gradients within Nafion in polymer electrolyte fuel cells  

Microsoft Academic Search

Water transport is an important consideration in the optimization of polymer electrolyte fuel cell (PEFC) performance, affecting both internal resistance and cathode polarization losses. Novel experiments are described using neutron radiography to measure water gradient profiles within Nafion{reg_sign} in an operating PEFC. Preliminary neutron intensity gradients show qualitative agreement with the expected response of membrane water content to changes in

R. J. Bellows; M. Y. Lin; M. Arif; A. K. Thompson; D. Jacobson

1999-01-01

303

Eulerian-Lagrangian analysis of transport conditioned on hydraulic data 2. Effects of log transmissivity and hydraulic head measurements  

Microsoft Academic Search

In paper 1 of this series we described an analytical-numerical method to predict deterministically solute transport under uncertainty. The method is based on a unified Eulerian-Lagrangian theory which allows conditioning of the predictions on hydraulic measurements. Conditioning on measured concentrations is also possible, as demonstrated by Neuman et al. (1993). In this paper we condition velocity on log transmissivity and\\/or

Dongxiao Zhang; Shlomo P. Neuman

1995-01-01

304

Simultaneous measurement of extracellular dopamine and dopamine transporter occupancy by cocaine analogs in squirrel monkeys  

PubMed Central

Several classes of drugs bind to the dopamine transporter (DAT) with high affinity, but some are weaker positive reinforcers than cocaine, suggesting that affinity for and occupancy of the DAT is not the only determinant of a drug’s reinforcing effectiveness. Other factors such as the rate of onset have been positively and strongly correlated with the reinforcing effects of DAT inhibitors in nonhuman primates. In the current studies, we examined the effects of acute systemic administration of cocaine and three cocaine analogs (RTI-150, RTI-177, and RTI-366) on binding to DAT in squirrel monkey brain using PET neuroimaging. During the PET scan, we also measured drug effects on dopamine (DA) levels in the caudate using in vivo microdialysis. In general, our results suggest a lack of concordance between drug occupancy at DAT and changes in DA levels. These studies also indicate that acute cocaine administration decreases the availability of plasma membrane DAT for binding, even after cocaine is no longer blocking DA uptake as evidence by a return to basal DA levels. PMID:22237864

Kimmel, Heather L.; Nye, Jonathon A.; Voll, Ronald; Stehouwer, Jeffrey; Goodman, Mark M.; Votaw, John R.; Carroll, F. I.; Howell, Leonard L.

2014-01-01

305

Effect of using a cowl when measuring the fiber number concentration by the membrane filter method.  

PubMed

This article compares samples taken with three different sampling heads: (1). open-faced sampling head, (2). open-faced sampling head with stainless-steel extension cowl, and (3). open-faced sampling head with graphite-impregnated extension cowl. Sampling was performed in three factories producing man-made mineral fibers (alkaline silicate fibers, refractory ceramic fibers, glass fibers). Flow rate was varied (1 L/min or 2 L/min). The average densities measured on the sampling filter for fibers of <3 microm in diameter varied from 19 to 91 fibers/mm(2). No significant difference in fiber density was observed in relation to the nature of the sampling head for fibers with a diameter of <3 microm. The deposits noted on the internal walls of the cowl were small and much less than that documented in the literature for man-made mineral fibers until now. They were greater for fibers with a diameter of >3 microm than for those with a diameter of <3 microm. For large-diameter fibers, it would appear that cowl deposit can be reduced by increasing the sampling flow rate. PMID:15238337

Kauffer, Edmond; Eypert-Blaison, Céline

2004-05-01

306

High-Reynolds Number Active Blowing Semi-Span Force Measurement System Development  

NASA Technical Reports Server (NTRS)

Recent wind-tunnel tests at the NASA Langley Research Center National Transonic Facility utilized high-pressure bellows to route air to the model for evaluating aircraft circulation control. The introduction of these bellows within the Sidewall Model Support System significantly impacted the performance of the external sidewall mounted semi-span balance. As a result of this impact on the semi-span balance measurement performance, it became apparent that a new capability needed to be built into the National Transonic Facility s infrastructure to allow for performing pressure tare calibrations on the balance in order to properly characterize its performance under the influence of static bellows pressure tare loads and bellows thermal effects. The objective of this study was to design both mechanical calibration hardware and an experimental calibration design that can be employed at the facility in order to efficiently and precisely perform the necessary loadings in order to characterize the semi-span balance under the influence of multiple calibration factors (balance forces/moments and bellows pressure/temperature). Using statistical design of experiments, an experimental design was developed allowing for strategically characterizing the behavior of the semi-span balance for use in circulation control and propulsion-type flow control testing at the National Transonic Facility.

Lynn, Keith C.; Rhew, Ray D.; Acheson, Michael J.; Jones, Gregory S.; Milholen, William E.; Goodliff, Scott L.

2012-01-01

307

Promoter methylation of serotonin transporter gene is associated with obesity measures: a monozygotic twin study  

PubMed Central

Objective: Epigenetic mechanisms are increasingly being recognized as an important factor for obesity. The serotonin transporter gene (SLC6A4) has a critical role in regulating food intake, body weight and energy balance. This study examines the potential association between SLC6A4 promoter methylation and obesity measures in a monozygotic (MZ) twin sample. Methods: We studied 84 MZ twin pairs drawn from the Vietnam Era Twin Registry. Obesity measures include body mass index (BMI), body weight, waist circumference (WC) and waist-hip ratio (WHR). The SLC6A4 promoter methylation profile in peripheral blood leukocytes was quantified by bisulfite pyrosequencing. The association between methylation variation and obesity parameters was examined by mixed-model regression and matched pair analysis, adjusting for age, smoking, alcohol consumption, physical activity and total daily energy intake. Multiple testing was controlled using the adjusted false discovery rate (q-value). Results: Mean methylation level was positively correlated with BMI (r=0.29; P=0.0002), body weight (r=0.31; P<0.0001) and WC (r=0.20; P=0.009), but not WHR. Intra-pair differences in mean methylation were significantly correlated with intra-pair differences in BMI, body weight and WC, but not WHR. On average, a 1% increase in mean methylation was associated with 0.33?kg?m?2 increase in BMI (95% CI: 0.02–0.65; P=0.03), 1.16?kg increase in body weight (95% CI, 0.16–2.16; P=0.02) and 0.78?cm increase in WC (95% CI, 0.05–1.50; P=0.03) after controlling for potential confounders. Conclusions: SLC6A4 promoter hypermethylation is significantly associated with an increased prevalence of obesity within a MZ twin study. PMID:22290534

Zhao, J; Goldberg, J; Vaccarino, V

2013-01-01

308

Improving stratospheric transport trend analysis based on SF6 and CO2 measurements  

NASA Astrophysics Data System (ADS)

this study we reexamine nearly four decades of in situ balloon-based stratospheric observations of SF6 and CO2 with an idealized model and reanalysis products. We use new techniques to account for the spatial and temporal inhomogeneity of the sparse balloon profiles and to calculate stratospheric mean ages of air more consistently from the observations with the idealized model. By doing so we are able to more clearly show and account for the variability of mean age of air throughout the bulk of the depth of the stratosphere. From an idealized model guided by the observations, we identify variability in the mean age due to the seasonal cycle of stratospheric transport, the quasi-biennial oscillation in tropical zonal winds, major volcanic eruptions, and linear trends that vary significantly with altitude. We calculate a negative mean age trend in the lowest 5 km of the stratosphere that agrees within uncertainties with a trend calculated from a set of chemistry climate model mean ages in this layer. The mean age trends reverse sign in the middle and upper stratosphere and are in agreement with a previous positive trend estimate using the same observational data set, although we have substantially reduced the uncertainty on the trend. Our analysis shows that a long time series of in situ profile measurements of trace gases such as SF6 and CO2 can be a unique and useful indicator of stratospheric circulation variability on a range of time scales and an important contributor to help validate the stratospheric portion of global chemistry climate models. However, with only SF6 and CO2 measurements, the competing effects on mean age between mean circulation and mixing (tropical entrainment) are not uniquely separable.

Ray, Eric A.; Moore, Fred L.; Rosenlof, Karen H.; Davis, Sean M.; Sweeney, Colm; Tans, Pieter; Wang, Tao; Elkins, James W.; Bönisch, Harald; Engel, Andreas; Sugawara, Satoshi; Nakazawa, T.; Aoki, S.

2014-12-01

309

MAJOR TRANSPORT MECHANISMS OF PYRETHROIDS IN RESIDENTIAL SETTINGS AND EFFECTS OF MITIGATION MEASURES  

PubMed Central

The major pathways for transport of pyrethroids were determined in runoff studies conducted at a full-scale test facility in central California, USA. The 6 replicate house lots were typical of front lawns and house fronts of California residential developments and consisted of stucco walls, garage doors, driveways, and residential lawn irrigation sprinkler systems. Each of the 6 lots also included a rainfall simulator to generate artificial rainfall events. Different pyrethroids were applied to 5 surfaces—driveway, garage door and adjacent walls, lawn, lawn perimeter (grass near the house walls), and house walls above grass. The volume of runoff water from each house lot was measured, sampled, and analyzed to determine the amount of pyrethroid mass lost from each surface. Applications to 3 of the house lots were made using the application practices typically used prior to recent label changes, and applications were made to the other 3 house lots according to the revised application procedures. Results from the house lots using the historic application procedures showed that losses of the compounds applied to the driveway and garage door (including the adjacent walls) were 99.75% of total measured runoff losses. The greatest losses were associated with significant rainfall events rather than lawn irrigation events. However, runoff losses were 40 times less using the revised application procedures recently specified on pyrethroid labels. Environ Toxicol Chem 2014;33:52–60. © 2013 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited. PMID:24105831

Davidson, Paul C; Jones, Russell L; Harbourt, Christopher M; Hendley, Paul; Goodwin, Gregory E; Sliz, Bradley A

2014-01-01

310

DUF1220 copy number is linearly associated with increased cognitive function as measured by total IQ and mathematical aptitude scores.  

PubMed

DUF1220 protein domains exhibit the greatest human lineage-specific copy number expansion of any protein-coding sequence in the genome, and variation in DUF1220 copy number has been linked to both brain size in humans and brain evolution among primates. Given these findings, we examined associations between DUF1220 subtypes CON1 and CON2 and cognitive aptitude. We identified a linear association between CON2 copy number and cognitive function in two independent populations of European descent. In North American males, an increase in CON2 copy number corresponded with an increase in WISC IQ (R (2) = 0.13, p = 0.02), which may be driven by males aged 6-11 (R (2) = 0.42, p = 0.003). We utilized ddPCR in a subset as a confirmatory measurement. This group had 26-33 copies of CON2 with a mean of 29, and each copy increase of CON2 was associated with a 3.3-point increase in WISC IQ (R (2) = 0.22, p = 0.045). In individuals from New Zealand, an increase in CON2 copy number was associated with an increase in math aptitude ability (R (2) = 0.10 p = 0.018). These were not confounded by brain size. To our knowledge, this is the first study to report a replicated association between copy number of a gene coding sequence and cognitive aptitude. Remarkably, dosage variations involving DUF1220 sequences have now been linked to human brain expansion, autism severity and cognitive aptitude, suggesting that such processes may be genetically and mechanistically inter-related. The findings presented here warrant expanded investigations in larger, well-characterized cohorts. PMID:25287832

Davis, Jonathon M; Searles, Veronica B; Anderson, Nathan; Keeney, Jonathon; Raznahan, Armin; Horwood, L John; Fergusson, David M; Kennedy, Martin A; Giedd, Jay; Sikela, James M

2015-01-01

311

Measurement of the amount and number of pollen particles of Cryptomeria japonica (taxodiaceae) by imaging with a photoacoustic microscope.  

PubMed

A photoacoustic microscope (PAM), which includes a condenser microphone and a pair of linear-motor-driven pulse stages, was specially designed for spectroscopic applications. The PAM was applied to measure the amount and number of pollen particles of Cryptomeria japonica (CJ), which is known for its allergic function against eyes and nose. The advantage of photoacoustic (PA) imaging is both its high sensitivity and its counting ability up to high concentrations of the specimen. The CJ pollen particles were fixed on a piece of adhesive tape or on albumen (egg white) on a glass slide set in a PA cell. The PA image showed the ability of this method to count CJ pollen from the several-hundred-milligram region to even a single particle. The PA signal obtained was integrated over the specimen surface. The dependence of the PA signal on the amount or number of the pollen particles was measured. The resulting coefficients of correlation of the calibration curves for the amount and the number of pollen particles were 0.94 and 0.97, respectively. PMID:16555767

Miyamoto, Katsuhiko; Hoshimiya, Tsutomu

2006-03-01

312

Optical and transport measurement and first-principles determination of the ScN band gap  

NASA Astrophysics Data System (ADS)

The electronic structure of scandium nitride is determined by combining results from optical and electronic transport measurements with first-principles calculations. Hybrid functional Heyd-Scuseria-Ernzerhof (HSE06) calculations indicate a 0.92 eV indirect ? to X band gap and direct transition energies of 2.02 and 3.75 eV at X and ? points, respectively, while GoWo and G Wo methods suggest 0.44-0.74 eV higher gap values. Epitaxial ScN(001) layers deposited on MgO(001) substrates by reactive sputtering exhibit degenerate n -type semiconductor properties with a temperature-independent electron density that is varied from N =1.12 -12.8 ×1020c m-3 using fluorine impurity doping. The direct optical gap increases linearly with N from 2.18 to 2.70 eV, due to a Burstein-Moss effect. This strong dependence on N is likely the cause for the large range (2.03-3.2 eV) of previously reported gap values. However, here extrapolation to N =0 yields 2.07 ±0.05 eV for the direct X point transition of intrinsic ScN. A reflection peak at 3.80 ±0.02 eV is independent of N and in perfect agreement with the HSE06-predicted peak at 3.79 eV, associated with a high joint density of states (DOS) near the ? point. The electron mobility at 4 K is 100 ±30 c m2/Vs and decreases with temperature due to scattering at polar optical phonons with characteristic frequencies that decrease from 620 to 440 ±30 cm-1 , with increasing N , due to free carrier screening. The transport and DOS electron effective mass, determined from measured intra- and interband transitions, respectively, are 0.40 ±0.02 mo and 0.33 ±0.02 mo , in good agreement with the first-principles predictions of mt r=0.33 ±0.05 mo and mDOS=0.43 ±0.05 mo . The ScN refractive index increases with increasing h ? =1.0 -2.0 eV from 2.6-3.1 based on optical measurements and from 2.8-3.2 based on the calculated dielectric function. An overall comparison of experiment and simulation indicates (i) an overestimation of band gaps by GW methods, but (ii) excellent agreement with a deviation of ?0.05 eV for the hybrid functional and (iii) a value for the fundamental indirect gap of ScN of 0.92 ±0.05 eV .

Deng, Ruopeng; Ozsdolay, B. D.; Zheng, P. Y.; Khare, S. V.; Gall, D.

2015-01-01

313

Viscous flow through slowly expanding or contracting porous walls with low seepage Reynolds number: a model for transport of biological fluids through vessels.  

PubMed

In this article, the problem of laminar, isothermal, incompressible and viscous flow in a rectangular domain bounded by two moving porous walls, which enable the fluid to enter or exit during successive expansions or contractions, is investigated. The governing non-linear equations and their associated boundary conditions are transformed into a highly non-linear ordinary differential equation. The series solution of the problem is obtained by utilising the homotopy perturbation method. Graphical results are presented to investigate the influence of the non-dimensional wall dilation rate and seepage Reynolds number (Re) on the velocity, normal pressure distribution and wall shear stress. Since the transport of biological fluids through contracting or expanding vessels is characterised by low seepage Res, the current study focuses on the viscous flow driven by small wall contractions and expansions of two weakly permeable walls. PMID:21347910

Dinarvand, Saeed

2011-10-01

314

Sediment transport time measured with U-series isotopes: Results from ODP North Atlantic drift site 984  

NASA Astrophysics Data System (ADS)

High precision uranium isotope measurements of marine clastic sediments are used to measure the transport and storage time of sediment from source to site of deposition. The approach is demonstrated on fine-grained, late Pleistocene deep-sea sediments from Ocean Drilling Program Site 984A on the Bjorn Drift in the North Atlantic. The sediments are siliciclastic with up to 30% carbonate, and dated by ?18O of benthic foraminifera. Nd and Sr isotopes indicate that provenance has oscillated between a proximal source during the last three interglacial periods - volcanic rocks from Iceland - and a distal continental source during glacial periods. An unexpected finding is that the 234U/ 238U ratios of the silicate portion of the sediment, isolated by leaching with hydrochloric acid, are significantly less than the secular equilibrium value and show large and systematic variations that are correlated with glacial cycles and sediment provenance. The 234U depletions are inferred to be due to ?-recoil loss of 234Th, and are used to calculate "comminution ages" of the sediment — the time elapsed between the generation of the small (? 50 ?m) sediment grains in the source areas by comminution of bedrock, and the time of deposition on the seafloor. Transport times, the difference between comminution ages and depositional ages, vary from less than 10 ky to about 300 to 400 ky for the Site 984A sediments. Long transport times may reflect prior storage in soils, on continental shelves, or elsewhere on the seafloor. Transport time may also be a measure of bottom current strength. During the most recent interglacial periods the detritus from distal continental sources is diluted with sediment from Iceland that is rapidly transported to the site of deposition. The comminution age approach could be used to date Quaternary non-marine sediments, soils, and atmospheric dust, and may be enhanced by concomitant measurement of 226Ra/ 230Th, 230Th/ 234U, and cosmogenic nuclides.

DePaolo, Donald J.; Maher, Kate; Christensen, John N.; McManus, Jerry

2006-08-01

315

An association between a dopamine transporter gene (SLC6A3) haplotype and ADHD symptom measures in nonclinical adults.  

PubMed

Previous genetic studies have postulated that attention deficit hyperactivity disorder (ADHD) should be regarded as the extreme end of a set of behavioural traits that can be continuously measured in the general population. The current study adopted a quantitative trait approach to examine the relationship between dopamine gene variants and self-reported ADHD symptoms in 517 nonclinical adults. Although genetic associations with variants of both the dopamine transporter (DAT1; SLC6A3) and D4 receptor (DRD4) genes have been reliably reported in children, results in adults are less consistent. We probed two potentially functional variable number of tandem repeat (VNTR) polymorphisms in the 3'UTR and intron 8 of DAT1, the 10-repeat and 6-repeat alleles of which respectively form a haplotype (10/6 DAT1 haplotype) that is associated with childhood ADHD. We also genotyped the exon 3 VNTR of DRD4, the 7-repeat allele of which is also an established risk factor for childhood ADHD. Permutation analysis showed an influence of the 10/6 DAT1 haplotype on both CAARS-G and CAARS-H (DSM-IV ADHD Symptoms Total and ADHD Index respectively), such that ADHD symptom scores increased with each additional copy of the 10/6 DAT1 haplotype. This result survived corrections for multiple comparisons both at the level of genotype and phenotype. A nominal association with CAARS-G was also found for the 7-repeat allele of the DRD4 VNTR however this did not survive multiple comparison correction. Our results provide further support for the influence of variation in the 10/6 DAT1 haplotype and individual differences in ADHD symptoms in adults. © 2015 Wiley Periodicals, Inc. PMID:25656223

Tong, Janette H S; Cummins, Tarrant D R; Johnson, Beth P; McKinley, Leigh-Anne; Pickering, Hayley E; Fanning, Peter; Stefanac, Nicole R; Newman, Daniel P; Hawi, Ziarih; Bellgrove, Mark A

2015-03-01

316

Hole-induced electron transport through core-shell quantum dots: a direct measurement of the electron-hole interaction.  

PubMed

Quantum dots (QDs) have promising optoelectronic properties. Colloidal QD heterostructures, systems in which two semiconductors are incorporated in a single colloid, may show novel and potentially useful transport phenomena. Here, we report on the physical mechanisms of charge transport through PbSe-CdSe core-shell QDs measured with cryogenic scanning tunneling spectroscopy. Compared to single-component QDs, an additional hole-induced electron tunneling channel is found. Electron tunneling with and without a hole occurs at different bias, allowing the determination of the electron-hole interaction energy (80 meV). This energy is sufficiently large to allow for a transport regime at room temperature in which electrons tunnel into the dot only if a hole is present, an ideal situation for controlled single-photon emission. PMID:20392107

Swart, Ingmar; Sun, Zhixiang; Vanmaekelbergh, Daniël; Liljeroth, Peter

2010-05-12

317

Fluvial sediments a summary of source, transportation, deposition, and measurement of sediment discharge  

USGS Publications Warehouse

This paper presents a broad but undetailed picture of fluvial sediments in streams, reservoirs, and lakes and includes a discussion of the processes involved in the movement of sediment by flowing water. Sediment is fragmental material that originates from the chemical or physical disintegration of rocks. The disintegration products may have many different shapes and may range in size from large boulders to colloidal particles. In general, they retain about the same mineral composition as the parent rocks. Rock fragments become fluvial sediment when they are entrained in a stream of water. The entrainment may occur as sheet erosion from land surfaces, particularly for the fine particles, or as channel erosion after the surface runoff has accumulated in streams. Fluvial sediments move in streams as bedload (particles moving within a few particle diameters of the streambed) or as suspended sediment in the turbulent flow. The discharge of bedload varies with several factors, which may include particle size and a type of effective shear on the surface of the streambed. The discharge of suspended sediment depends partly on concentration of moving sediment near the streambed and hence on discharge of bedload. However, the concentration of fine sediment near the streambed varies widely, even for equal flows, and, therefore, the discharge of fine sediment normally cannot be computed theoretically. The discharge of suspended sediment also depends on velocity, turbulence, depth of flow, and fall velocity of the particles. In general, the coarse sediment transported by a stream moves intermittently and is discharged at a rate that depends on properties of the flow and of the sediment. If an ample supply of coarse sediment is available at the surface of the streambed, the discharge of the coarse sediment, such as sand, can be roughly computed from properties of the available sediment and of the flow. On the other hand, much of the fine sediment in a stream usually moves nearly continuously at about the velocity of the flow, and even low flows can transport large amounts of fine sediment. Hence, the discharge of fine sediments, being largely dependent on the availability of fine sediment upstream rather than on the properties of the sediment and of the flow at a cross section, can seldom be computed from properties, other than concentrations based directly on samples, that can be observed at the cross section. Sediment particles continually change their positions in the flow; some fall to the streambed, and others are removed from the bed. Sediment deposits form locally or over large areas if the volume rate at which particles settle to the bed exceeds the volume rate at which particles are removed from the bed. In general, large particles are deposited more readily than small particles, whether the point of deposition is behind a rock, on a flood plain, within a stream channel, or at the entrance to a reservoir, a lake, or the ocean. Most samplers used for sediment observations collect a water-sediment mixture from the water surface to within a few tenths of a foot of the streambed. They thus sample most of the suspended sediment, especially if the flow is deep or if the sediment is mostly fine; but they exclude the bedload and some of the suspended sediment in a layer near the streambed where the suspended-sediment concentrations are highest. Measured sediment discharges are usually based on concentrations that are averages of several individual sediment samples for a cross section. If enough average concentrations for a cross section have been determined, the measured sediment discharge can be computed by interpolating sediment concentrations between sampling times. If only occasional samples were collected, an average relation between sediment discharge and flow can be used with a flow-duration curve to compute roughly the average or the total sediment discharges for any periods of time for which the flow-duration c

Colby, B.R.

1963-01-01

318

Measurement of Turbulence Decorrelation during Transport Barrier Evolution in a High Temperature Fusion Plasma  

SciTech Connect

A low power polychromatic beam of microwaves is used to diagnose the behavior of turbulent fluctuations in the core of the JT-60U tokamak during the evolution of the internal transport barrier. A continuous reduction in the size of turbulent structures is observed concomitant with the reduction of the density scale length during the evolution of the internal transport barrier. The density correlation length decreases to the order of the ion gyroradius, in contrast to the much longer scale lengths observed earlier in the discharge, while the density fluctuation level remain similar to the level before transport barrier formation.

R. Nazikian; K. Shinohara; G.J. Kramer; E. Valeo; K. Hill; T.S. Hahm; G. Rewoldt; S. Ide; Y. Koide; Y. Oyama; H. Shirai; W. Tang

2005-03-29

319

Transportable distance measurement system based on superheterodyne interferometry using two phase-locked frequency-doubled Nd:YAG lasers.  

PubMed

We describe a transportable distance measurement system based on synthetic wavelength interferometry. Two frequency-doubled Nd:yttrium aluminum garnet lasers at 532 nm are used to generate a synthetic wavelength of approximately 2.5 cm. A nonpolarizing interferometric system has been set up to eliminate polarization cross-talk issue. A superheterodyne detection was performed to measure the synthetic phase and to determine absolute distances. The capability to achieve fringe interpolation of 2pi/5600 has been demonstrated and an agreement in distance measurement at the 4 microm level has been achieved, compared to an optical interferometric 3 m long displacement bench. PMID:20515129

Azouigui, S; Badr, T; Wallerand, J-P; Himbert, M; Salgado, J; Juncar, P

2010-05-01

320

MIT commuter common : measuring and improving the transportation footprint of an urban institution  

E-print Network

This thesis develops a system for observing, visualizing, and understanding transportation behavior at the scale of an urban institution's entire population. In particular, the Massachusetts institute of Technology (MIT) ...

Winder, James Ira

2013-01-01

321

Spatially resolved in situ measurements of the transport of organic molecules in a polycrystalline nanoporous membrane  

E-print Network

, nanoporous molecular sieve membrane, with micron-scale resolution. A method based on photoacoustic of photoacoustic signal generation from a heterogeneous membrane, allows extraction of concentration profiles and theoretical descriptions of molecular transport in these tightly confined nanoporous environments, remain

Nair, Sankar

322

Dust transport over the eastern Mediterranean derived from Total Ozone Mapping Spectrometer, Aerosol Robotic Network, and surface measurements  

NASA Astrophysics Data System (ADS)

Multiyear surface PM10 measurements performed on Crete Island, Greece, have been used in conjunction with satellite (Total Ozone Mapping Spectrometer (TOMS)) and ground-based remote sensing measurements (Aerosol Robotic Network (AERONET)) to enhance our understanding of the evolution of mineral dust events over the eastern Mediterranean. An analysis of southerly air masses at altitudes of 1000 and 3000 m over a 5 year period (2000-2005), showed that dust can potentially arrive over Crete, either simultaneously in the lower free troposphere and inside the boundary layer (vertical extended transport (VET)) or initially into the free troposphere with the heavier particles gradually being scavenged inside the boundary layer (free troposphere transport (FTT)). Both pathways present significant seasonal variations but on an annual basis contribute almost equally to the dust transport in the area. During VET the aerosol index (AI) derived from TOMS was significantly correlated with surface PM10, and in general AI was found to be adequate for the characterization of dust loadings over the eastern Mediterranean on a climatological basis. A significant covariance between PM10 and AOT was observed during VET as well, indicating that AOT levels from AERONET may be estimated by PM10 levels at the surface. Surface measurements are thus crucial for the validation of remote sensing measurements and hence are a powerful tool for the investigation of the impact of aerosols on climate.

Kalivitis, N.; Gerasopoulos, E.; Vrekoussis, M.; Kouvarakis, G.; Kubilay, N.; Hatzianastassiou, N.; Vardavas, I.; Mihalopoulos, N.

2007-02-01

323

Optimal two-qubit tomography based on local and global measurements: Maximal robustness against errors as described by condition numbers  

NASA Astrophysics Data System (ADS)

We present an error analysis of various tomographic protocols based on the linear inversion for the reconstruction of an unknown two-qubit state. We solve the problem of finding a tomographic protocol which is the most robust against errors in terms of the lowest value (i.e., equal to 1) of a condition number, as required by the Gastinel-Kahan theorem. In contrast, standard tomographic protocols, including those based on mutually unbiased bases, are nonoptimal for determining all the 16 elements of an unknown two-qubit density matrix. Our method is based on the measurements of the 16 generalized Pauli operators, where twelve of them can be locally measured, and the other four require nonlocal Bell measurements. Our method corresponds to selectively measuring, one by one, all the real and imaginary elements of an unknown two-qubit density matrix. We describe two experimentally feasible setups of this protocol for the optimal reconstruction of two photons in an unknown polarization state using conventional detectors and linear-optical elements. Moreover, we define the operators for the optimal reconstruction of the states of multiqubit or multilevel (qudit) systems.

Miranowicz, Adam; Bartkiewicz, Karol; Pe?ina, Jan; Koashi, Masato; Imoto, Nobuyuki; Nori, Franco

2014-12-01

324

Direct measurements of transport and water properties through the Bering Strait  

Microsoft Academic Search

Four years of temperature, salinity, and velocity data enable a direct computation of volume transport and a temporal description of water properties exchanged through the Bering Strait. The mean volume transport over the 4-year period (September 1990 through September 1994) is 0.83 Sv northward with a weekly standard deviation of 0.66 Sv. The maximum error in this mean estimate is

A. T. Roach; K. Aagaard; C. H. Pease; S. A. Salo; T. Weingartner; V. Pavlov; M. Kulakov

1995-01-01

325

Lateral subsurface stormflow and solute transport in a forested hillslope: A combined measurement and modeling approach  

NASA Astrophysics Data System (ADS)

flow dominates water movement and solute transport in boreal forest hillslopes. However, only a few model applications to date have accounted for preferential flow at forest sites. Here we present a parallel and coupled simulation of flow and transport processes in the preferential flow domain and soil matrix of a forested hillslope section in Kangaslampi, Finland, using a new, three-dimensional, physically based dual-permeability model. Our aim is to simulate lateral subsurface stormflow and solute transport at the slope during a chloride tracer experiment, and to investigate the role of preferential flow in the tracer transport. The model was able to mimic the observed tracer transport during tracer irrigation, but overestimated the dilution velocity of the tracer plume in the highly conductive soil horizons near the soil surface after changing the irrigation to tracer-free water. According to the model, 140 times more chloride was transported downslope in the preferential flow domain than in the soil matrix during the tracer irrigation. The simulations showed, together with reference simulations with a traditional one pore domain model, that a two pore domain approach was required to simulate the observed flow and transport event. The event was characterized by the transmissivity feedback phenomenon and controlled by preferential flow mechanisms, in particular by lateral by-pass flow. According to our results, accounting for the slow-flow and fast-flow domains of soil, as well as the water and solute exchange between the domains, is essential for a successful simulation of flow and solute transport in preferential flow dominated hillslopes.

Laine-Kaulio, Hanne; Backnäs, Soile; Karvonen, Tuomo; Koivusalo, Harri; McDonnell, Jeffrey J.

2014-10-01

326

Static and dynamic pressure measurements on a NACA 0012 airfoil in the Ames High Reynolds Number Facility  

NASA Technical Reports Server (NTRS)

The supercritical flows at high subsonic speeds over a NACA 0012 airfoil were studied to acquire aerodynamic data suitable for evaluating numerical-flow codes. The measurements consisted primarily of static and dynamic pressures on the airfoil and test-channel walls. Shadowgraphs were also taken of the flow field near the airfoil. The tests were performed at free-stream Mach numbers from approximately 0.7 to 0.8, at angles of attack sufficient to include the onset of buffet, and at Reynolds numbers from 1 million to 14 million. A test action was designed specifically to obtain two-dimensional airfoil data with a minimum of wall interference effects. Boundary-layer suction panels were used to minimize sidewall interference effects. Flexible upper and lower walls allow test-channel area-ruling to nullify Mach number changes induced by the mass removal, to correct for longitudinal boundary-layer growth, and to provide contouring compatible with the streamlines of the model in free air.

Mcdevitt, J. B.; Okuno, A. F.

1985-01-01

327

An overview of underwater sound generated by interparticle collisions and its application to the measurements of coarse sediment bedload transport  

NASA Astrophysics Data System (ADS)

Over the past 2 to 3 decades the concept of using sound generated by the interparticle collisions of mobile bed material has been investigated to assess if underwater sound can be utilised as a proxy for the estimation of bedload transport. In principle the acoustic approach is deemed to have the potential to provide non-intrusive, continuous, high-temporal-resolution measurements of bedload transport. It has been considered that the intensity of the sound radiated should be related to the amount of mobile material and the frequency spectrum to the size of the material. To be able to fully realise this use of acoustics requires an understanding of the parameters which control the generation of sound as particles impact. In the present work the aim is to provide scientists developing acoustics to measure bedload transport with a description of how sound is generated when particles undergo collision underwater. To investigate the properties of the sound generated, examples are provided under different conditions of impact. It is considered that providing an overview of the origins of the sound generation will provide a basis for the interpretation of acoustic data, collected in the marine environment for the study of bedload sediment transport processes.

Thorne, P. D.

2014-12-01

328

Characteristics of submicron aerosol number size distribution and new particle formation events measured in Seoul, Korea, during 2004-2012  

NASA Astrophysics Data System (ADS)

The diurnal and seasonal characteristics of the submicron aerosol size distribution measured in Seoul for a long term (2004-2012) were analyzed. The average diurnal variation of aerosol number size distribution showed a single modal distribution but the modal diameter varied around 35 nm and the total aerosol concentration varied diurnally with the maximum during the rush hour. To identify the dominant patterns of the diurnal variation of aerosol number size distribution, the cyclostationary empirical orthogonal function (CSEOF) method was employed. The first CSEOF mode revealed the dominant diurnal pattern that represented an urban life pattern. The principal component (PC) values of the first CSEOF mode showed clear seasonal variation. The PC values were the largest in winter months due to winter monsoon that brought polluted air masses from China, and larger traffic emission amount during the winter season. New particle formation (NPF) events were found to occur on 12.3% of the total measurement days in Seoul when classified with a subjective method. NPF frequency varied seasonally, with the maximum in spring. The second CSEOF mode was found to represent NPF events. A way to identify NPF event days by the CSEOF method was proposed and generally performed well but with some exceptions. The favorable conditions for NPF events in Seoul were found to be low RH, low condensation sink, and low cloud cover, which is consistent with some previous studies. Lastly, the relative contribution of NPF to ultrafine aerosol in Seoul was estimated to be~32%.

Park, Minsu; Yum, Seong Soo; Kim, Jong Hwan

2015-01-01

329

First Measurements of Neutral Atmospheric Cluster and 1–2 nm Particle Number Size Distributions During Nucleation Events  

SciTech Connect

Recent observations throughout the atmosphere have shown that nucleation occurs frequently (Kulmala et al. 2004). Modeling studies and observations have shown that nucleated particles contribute significantly to concentrations of cloud condensation nuclei (Spracklen et al. 2008), thereby affecting climate (IPCC 2007). Size-resolved measurements extending down to molecular dimensions can provide information on processes that lead to nucleation and would enable development and verification of theories for particle nucleation and growth in the atmosphere and other aerosol systems. This article describes measurements of the complete number size distribution, spanning the size range from vapor molecules and molecular clusters to submicrometer particles, during atmospheric nucleation events. The measurements used two new instruments, the cluster chemical ionization mass spectrometer (Cluster CIMS) and the DEG SMPS. The Cluster CIMS measures neutral molecular clusters from 50 to 900 amu. The DEG SMPS is a scanning mobility particle spectrometer (SMPS) equipped with a diethylene glycol (DEG)-based condensation particle counter (CPC) capable of 1.1 nm mobility diameter particle detection, and overlapping the sizes detected by the Cluster CIMS (Iida et al. 2009; Jiang et al. 2011). The Cluster CIMS distinguishes neutral clusters from ions formed by ion-induced clustering by varying the reaction time for ions with the sampled air (Zhao et al. 2010). It distinguishes clusters from high molecular weight gases by measuring the incremental signal at a specified mass detected during nucleation events. The clusters that were measured in this study contain sulfuric acid, which is known to participate in atmospheric nucleation (Kuang et al. 2008).

Jiang, J.; Kuang, C.; Zhao, J.; Chen, M.; Eisele, F. L.; Scheckman, J.; Williams, B. J.; McMurry, P. H.

2011-02-01

330

Modelling mineral dust lifting and transport in GEM-AQ: Sensitivity studies and comparison with measurements  

NASA Astrophysics Data System (ADS)

As one of the major contributors to the global yearly aerosol production, mineral dust has a significant impact on the regional and global climate as well as air quality. A dust emission and deposition module, based on the work of Zender (2003) (Dust Entrainment and Deposition (DEAD) Model), is developed and implemented in the Canadian Global Environmental Multiscale Air Quality (GEM-AQ) (Kaminski et al., 2008) model. Sensitivity tests for dust lifting mechanism are carried out in both a box model and the GEM-AQ model. It has been found that the particle size distribution in the parent soil plays also an important role in determining the dust emission. Dust source regions such as Northern Africa and Northern China respond to the parameterizations of dust emission scheme with different sensitivities in GEM-AQ. For the fist time, the input data for surface roughness length and particle size distribution, which are obtained by either field measurements or remote sensing techniques in the soils of the arid and semi-arid areas worldwide, are implemented and the different parameterizations of a dust emission scheme are suggested and applied into different dust source regions in a global scale for the GEM-AQ model. While compared to satellite measurements TOMS, the GEM-AQ model yields promising results in correctly detecting both the 'hot spots' and the relative strength of dust emissions for dust source areas. The total dust emission in 2001 is predicted by the GEM-AQ as 3.6x103 Tg1. Dust removal processes including the dry and wet depositions are also integrated in our dust module in GEM-AQ. Dry deposition dominates in the dust source regions and can account for up to 50% of dust removal. Wet deposition is dominant in the regions located downwind of dust source areas, particularly over the ocean surface, and could be responsible for up to 80% of dust removal from the atmosphere. Global pictures for different seasons of 2001 illustrating the relative contributions of both deposition processes to the removal of dust particles are generated by GEM-AQ. Several regions of strong dry and wet deposition are identified and North America appears to be the region where dry and wet depositions play an equally important role in dust removal. Several ground-based measurements such as the AERONET and IMPROVE are also used in this study to evaluate the GEM-AQ performance in modeling dust activity. The historic dust storms that occurred in Eastern Asia and North America are simulated with the configurations of global variable resolution (GV) in GEM-AQ and the model yields promising results compared to measurements, being able to properly reproduce the magnitude of dust aerosol in the background as well as to capture the dates of peaks for those dust episodes at various observational sites. In addition, examination of dust vertical distribution in GEM-AQ reveals that dust particles can be vertically transported up to the tropopause in sub-tropical region between 30°5 and 30° N. 1Tg =1012 g

Wu, Hao

331

Monitoring snowmelt and solute transport at Oslo airport by combining time-lapse electrical resistivity, soil water sampling and tensiometer measurements  

NASA Astrophysics Data System (ADS)

Monitoring contaminant transport at contaminated sites requires optimization of the configuration of a limited number of samplings points combined with heterogeneous flow and preferential flowpaths. Especially monitoring processes in the unsaturated zone is a major challenge due to the limited volume monitored by for example suction cups and their risk to clog in a highly active degradation zone. To make progress on soil contamination assessment and site characterization there is a strong need to integrate field-sale extensively instrumented tools, with non-invasive (geophysical) methods which provide spatially integrated measurements also in the unsaturated zone. Examples of sites that might require monitoring activities in the unsaturated zone are airports with winter frost where large quantities of de-icing chemicals are used each winter; salt and contaminant infiltration along roads; constructed infiltration systems for treatment of sewerage or landfill seepage. Electrical resistivity methods have proved to be useful as an indirect measurement of subsurface properties and processes at the field-scale. The non-uniqueness of the interpretation techniques can be reduced by constraining the inversion through the addition of independent geophysical measurements along the same profile. Or interpretation and understanding of geophysical images can be improved by the combination with classical measurements of soil physical properties, soil suction, contaminant concentration and temperatures. In our experiment, at the research field station at Gardermoen, Oslo airport, we applied a degradable de-icing chemical and an inactive tracer to the snow cover prior to snowmelt. To study the solute transport processes in the unsaturated zone time-lapse cross borehole electrical resistivity tomography (ERT) measurements were conducted at the same time as soil water samples were extracted at multiple depths with suction cups. Measurements of soil temperature, and soil tension were also carried out during the monitoring period. We present a selection of results from the snowmelt experiments and how the combination of measurement techniques can help interpret and understand the relative importance of the various contributions to the bulk electrical conductivity during snowmelt and solute transport.

Bloem, E.; French, H. K.

2013-12-01

332

VOLUME 80, NUMBER 1 P H Y S I C A L R E V I E W L E T T E R S 5 JANUARY 1998 Effect of Chemical Reactions and Phase Transitions on Turbulent Transport  

E-print Network

VOLUME 80, NUMBER 1 P H Y S I C A L R E V I E W L E T T E R S 5 JANUARY 1998 Effect of Chemical and number densities of admixtures. [S0031-9007(97)04944-2] PACS numbers: 47.27.Qb, 47.70.­n The problem- spheres of the Earth and planets, environmental physics, turbulent combustion). In recent years transport

Elperin, Tov

333

Development of vacuum ultraviolet absorption spectroscopy system for wide measurement range of number density using a dual-tube inductively coupled plasma light source  

SciTech Connect

A vacuum ultraviolet absorption spectroscopy system for a wide measurement range of atomic number densities is developed. Dual-tube inductively coupled plasma was used as a light source. The probe beam profile was optimized for the target number density range by changing the mass flow rate of the inner and outer tubes. This system was verified using cold xenon gas. As a result, the measurement number density range was extended from the conventional two orders to five orders of magnitude.

Kuwahara, Akira; Matsui, Makoto; Yamagiwa, Yoshiki [Department of Mechanical Engineering, Shizuoka University, 3-5-4 Johoku, Naka-ku, Hamamatsu 432-8561, Shizuoka (Japan)

2012-12-15

334

Absolute calibration of neutron detection systems on TFTR and accurate comparison of source strength measurements to transport simulations (invited)  

NASA Astrophysics Data System (ADS)

Accurate, absolutely calibrated measurements of the neutron source strength are needed for determining the quality of plasma performance, for constraining transport analysis, and for studying fast ion physics such as triton burnup. Obtaining an accurate calibration involves more than performing in situ source calibrations. Efforts on TFTR illustrate the additional need for careful detector characterization, periodic renormalization, and proper cross calibration of less sensitive detectors. Multiple detector systems have been developed on TFTR to provide redundancy and a range of energy sensitivity and time resolution. Three independently calibrated systems now agree in their determination of source strength within relative uncertainties of 15%-20%. These accurate neutron measurements can be effectively used to constrain transport simulations of neutral beam injection and test the modeling and simulation assumptions.

Barnes, Cris W.; Bell, M. G.; Hendel, H. W.; Jassby, D. L.; Mikkelsen, D.; Roquemore, A. L.; Scott, S. D.; Strachan, J. D.; Zarnstorff, M. C.

1990-10-01

335

Lead and tungsten pinhole inserts for I-131 SPECT tumor imaging: experimental measurements and photon transport simulations  

Microsoft Academic Search

The potential use of lead and tungsten pinhole inserts for high-resolution SPECT imaging of intratumor activity in I-131 radioimmunotherapy was investigated using experimental point source measurements and photon transport simulations. I-131 imaging is challenging because the primary photon emission is at 364 keV and penetration through the insert near the pinhole aperture is significant. Point source response functions (PSRF's) for

Mark F. Smith; Ronald J. Jaszczak; Huili Wang; Jianying Li

1997-01-01

336

ICET - International Collaboration on Experiments in Turbulence: Coordinated Measurements in High Reynolds Number Turbulent Boundary Layers from Three Wind Tunnels  

NASA Astrophysics Data System (ADS)

Zero pressure gradient (ZPG) boundary layers are one of the canonical, wall-bounded, turbulent flows that have been the focus of experimental and analytical investigations for several decades. Over the past few years, four groups have focused on systematic comparison between several measurement techniques and three facilities. Two closed return wind tunnels with ZPG boundary layers developed on a plate suspended near the mid-height of the test section (at KTH and IIT), and an open return facility with a large and long test section and a boundary layer developing along its floor (at the University of Melbourne), are used for these coordinated efforts. The development length of the boundary layers and the free-stream velocity in the three facilities range from 5.5 to 22 m, and from 10 to 60 m/s, respectively. Various arrangements for adjustable test section ceilings are employed to generate ZPG boundary layers over the range of momentum thickness Reynolds numbers from 11,000 to 70,000. Oil film interferometry (OFI) is employed to directly measure the wall shear stress, and various sizes of Pitot probes and types of hot-wire sensors are used to measure wall-normal velocity profiles at different locations and free-stream velocities. Mean velocity, turbulence statistics and integral parameters are examined.

Nagib, H.; Smits, A.; Marusic, I.; Alfredsson, P. H.

2009-11-01

337

Enhancing the characterization of bedload transport in rivers using the analogy between the Hertz contact theory and plate hydrophone measurements  

NASA Astrophysics Data System (ADS)

Vibration measurements performed with plate or pipe geophone/hydrophone systems are of growing interest for bedload transport monitoring since they allow performing high temporal resolution and continuous records. Our set-up is constituted by a piezoelectric hydrophone acting as a "sediment vibration sensor" in contact with a steel plate located on the streambed. With such an apparatus, the signal processing is generally reduced to power spectral analysis or impact counting. However, a large amount of useful information is contained in the waveform of the impact signal, which conveys the force and the contact time that the bedload imposes on the plate. The wave amplitude is not well constrained because it varies a lot with changing impact location and velocity. The wave frequency is a more relevant parameter, less sensitive to these variables. According to the Hertz contact theory the frequency of the first signal arrival (flexural wave) is directly proportional to the bed-material grain size. Then, an appropriate analysis of the frequency attributes (central frequency, modulation) is needed to estimate the size of bedload particles. In this way, we have developed a complete processing algorithm based on a high dimensional decomposition method (chirplet transform) to get an accurate estimation of the first arrival frequency content. Results on summer flood events in a lowland river show that impacts are well separated by their central frequency and that most of transport occurs during larger peak flows. The portion of coarser sediment which is characterized by low frequencies is preferentially transported during the rising limb whereas the finer sand fraction identified by higher frequencies is transported during both rising and falling limb. Such a processing offers the opportunity to better understand the bedload signature of vibration measurements and is promising in view of quantifying processes of bedload transport and deposition. This final objective of quantification is an ongoing research by performing a flume experiment with various impact velocity and granulometry (collaboration with the Hydrology Department of Trier University).

Barrière, Julien; Oth, Adrien; Schenkluhn, Reimar; Krein, Andreas

2014-05-01

338

Correlation between serotonin uptake in human blood platelets with the 44-bp polymorphism and the 17-bp variable number of tandem repeat of the serotonin transporter.  

PubMed

Dysfunctions of the central serotonin (5-hydroxytryptamine, 5-HT) system seem to be associated with psychiatric disorders such as schizophrenia or depression. Previous studies suggested that a 44-bp insertion/deletion polymorphism of the 5-HT transporter (5-HTT) promoter region might influence the transcriptional activity of the 5-HTT gene, and the insertion variant resulted in increased 5-HTT expression and 5-HT uptake. Moreover, a 17-bp variable number of tandem repeat (VNTR) polymorphism of the second intron may act as a transcriptional regulator with allele dependent differential enhancer-like properties. Since the 5-HTT of human platelets shares many properties with the transporter of neural tissue, platelets are widely used as a surrogate tissue source, possibly reflecting central 5-HT metabolism. Therefore, we investigated the impact of the 44-bp polymorphism and the 17-bp VNTR for 5-HT uptake in platelets of 50 male subjects. We found no significant effect of the 44-bp polymorphism and of the 17-bp VNTR on maximum rate (Vmax) of 5-HT uptake. However, individuals homozygous for the 5-HTT intron 2 allele with 12 repeats (STin2.12) of the 17-bp VNTR appeared to have lower affinity of 5-HT uptake than individuals heterozygous for the STin2.10/STin2.9 allele. This was also observed for the combined analysis of both polymorphisms. In conclusion, we found no association between the different genotypes of the 44-bp polymorphism and the 17-bp VNTR and maximum rate of 5-HT uptake into platelets. PMID:11920857

Kaiser, Rolf; Müller-Oerlinghausen, Bruno; Filler, Diana; Tremblay, Pierre-Benoit; Berghöfer, Anne; Roots, Ivar; Brockmöller, Jürgen

2002-04-01

339

Ultrafast, Unimpeded Liquid Water Transport Through Graphene-Based Nanochannels Measured by Isotope Labelling  

E-print Network

Graphene-based laminates, with ultralong and tortuous nanocapillaries formed by simply stacking graphene flakes together, have great promises in filtration and separation. However, the information on liquid water trans-membrane permeation is lacking, which is the most fundamental problem and of crucial importance in solution-based mass transport. Here, based on isotope labelling, we investigate the liquid water transportation through graphene-based nanocapillaries under no external hydrostatic pressures. Liquid water can afford an unimpeded permeation through graphene-based nanochannels with a diffusion coefficient 4~5 orders of magnitude larger than through sub-micrometer-sized polymeric channels. When dissolving ions in sources, the diffusion coefficient of ions through graphene channels lies in the same order of magnitude as water, while the ion diffusion is faster than water, indicating that the ions are mainly transported by fast water flows and the delicate interactions between ions and nanocapillary wa...

Sun, Pengzhan; Wang, Kunlin; Zhong, Minlin; Wu, Dehai; Zhu, Hongwei

2014-01-01

340

Wind Tunnel Measured Effects on a Twin-Engine Short-Haul Transport Caused by Simulated Ice Accretions: Data Report  

NASA Technical Reports Server (NTRS)

The purpose of this report is to release the data from the NASA Langley/Lewis 14 by 22 foot wind tunnel test that examined icing effects on a 1/8 scale twin-engine short-haul jet transport model. Presented in this document are summary data from the major configurations tested. The entire test database in addition to ice shape and model measurements is available as a data supplement in CD-ROM form. Data measured and presented are: wing pressure distributions, model force and moment, and wing surface flow visualization.

Reehorst, Andrew; Potapczuk, Mark; Ratvasky, Thomas; Laflin, Brenda Gile

1997-01-01

341

Number Line  

NSDL National Science Digital Library

In this brief article the numerous uses of the number line are detailed: counting, measurement, addition, subtraction, decimals, and fractions. The article contains visual representations of the some of the concepts and links to related topics.

2012-08-27

342

Measuring spatially resolved gas transport and adsorption in coal using MRI.  

PubMed

The storage and transport of gases in coal is of tremendous importance in the utilisation of coalbeds, and in particular the recovery of methane. There is also increasing interest in the use of coal mines as sites for carbon dioxide sequestration to alleviate the potentially harmful effects of global warming. This paper demonstrates the use of magnetic resonance imaging to investigate the spatiotemporal dynamics of gas transport in coal. The presence of significant structural heterogeneities in the coal was observed. Dynamical effects displayed a broad range of time constants ranging from minutes to days. PMID:11445356

Ramanathan, C; Bencsik, M

2001-01-01

343

Ultrafast liquid water transport through graphene-based nanochannels measured by isotope labelling.  

PubMed

Based on isotope labelling, we found that liquid water can afford an ultrafast permeation through graphene-based nanochannels with a diffusion coefficient 4-5 orders of magnitude greater than in the bulk case. When dissolving ions in sources, the diffusion coefficient of ions through graphene channels lies in the same order of magnitude as water, while the ion diffusion is slightly faster than water, indicating that the ions are mainly transported by water flows and the delicate interactions between ions and nanocapillary walls also take effect in the accelerated ion transportation. PMID:25608844

Sun, Pengzhan; Liu, He; Wang, Kunlin; Zhong, Minlin; Wu, Dehai; Zhu, Hongwei

2015-02-01

344

Index Numbers  

Microsoft Academic Search

Index numbers are used to aggregate detailed information on prices and quantities into scalar measures of price and quantity levels or their growth. The paper reviews four main approaches to bilateral index number theory where two price and quantity vectors are to be aggregated: fixed basket and average of fixed baskets, stochastic, test or axiomatic and economic approaches. The paper

Erwin Diewert

2007-01-01

345

Transport of NOx in East Asia identified by satellite and in situ measurements and Lagrangian particle dispersion model simulations  

NASA Astrophysics Data System (ADS)

dioxide (NO2) columns observed from space have been useful in detecting the increase of nitrogen oxides (NOx) emissions in East Asia, particularly China, coinciding with rapid economic growth during the past several decades. NO2 columns retrieved above a particular location reflect a combination of local NOx emissions and transported NOx from upwind sources. In this study, we demonstrate the transport of NOx emitted in East Asia using satellite and surface in situ measurements and Lagrangian particle dispersion model simulations. Enhanced satellite NO2 columns in the Yellow Sea (between China and South Korea) and the East Sea (between South Korea and Japan), and different seasonal variations of NO2 in China, North and South Korea, and Japan, suggest the importance of NOx transport in understanding the local NOx budget. Lagrangian transport model simulations with tracers of different chemical lifetimes identify source-receptor relationships that explain high NO2 over the oceans and springtime peaks in Korea and Japan, with China being the most likely source region. Our results have important implications for studies using satellite NO2 retrievals to derive NOx emissions at local scales in regions adjacent to large sources, such as in East Asia, Europe, and the Eastern U.S.

Lee, H.-J.; Kim, S.-W.; Brioude, J.; Cooper, O. R.; Frost, G. J.; Kim, C.-H.; Park, R. J.; Trainer, M.; Woo, J.-H.

2014-03-01

346

Detection of pollution transport events southeast of Mexico City using ground-based visible spectroscopy measurements of nitrogen dioxide  

NASA Astrophysics Data System (ADS)

This work presents ground based differential optical absorption spectroscopy (DOAS) measurements of nitrogen dioxide (NO2) during the MILAGRO field campaign in March 2006 at the Tenango del Aire research site located to the southeast of Mexico City. The DOAS NO2 column density measurements are used in conjunction with ceilometer, meteorological and surface nitric oxide (NO), nitrogen oxides (NOx) and total reactive nitrogen (NOy) measurements to analyze pollution transport events to the southeast of Mexico City during the MILARGO field campaign. The study divides the data set into three case study pollution transport events that occurred at the Tenango del Aire research site. The unique data set is then used to provide an in depth analysis of example days of each of the pollution transport events. An in depth analysis of 13 March 2006, a Case One day, shows the transport of several air pollution plumes during the morning through the Tenango del Aire research site when southerly winds are present and demonstrates how DOAS tropospheric NO2 vertical column densities (VCD), surface NO2 mixing ratios and ceilometer data are used to determine the vertical homogeneity of the pollution layer. The analysis of 18 March 2006, a Case Two day, shows that when northerly winds are present for the entire day, the air at the Tenango del Aire research site is relatively clean and no major pollution plumes are detected. Case 3 days are characterized by relatively clean air throughout the morning with large DOAS NO2 enhancements detected in the afternoon. The analysis of 28 March 2006 show the DOAS NO2 enhancements are likely due to lightning activity and demonstrate how suitable ground-based DOAS measruements are for monitoring anthropogenic and natural pollution sources that reside above the mixing layer.

Melamed, M. L.; Basaldud, R.; Steinbrecher, R.; Emeis, S.; Ruíz-Suárez, L. G.; Grutter, M.

2009-07-01

347

Determining the number of state psychiatric hospital beds by measuring quality of care with artificial neural networks.  

PubMed

This study uses a new paradigm to calculate the minimum and the optimum number of involuntary psychiatric beds at a state hospital in Maine with 5538 admissions over a 7-year period. The method measures quality of care (Q) based upon the accuracy of prediction of length-of-stay for the hospital, and of community length-of-stay for the community, each corrected for the severity of illness of the average patient. When Q in the hospital equals Q in the community, there is no net movement of patients from one phase of care to the other, analogous to a zero electromotive force, and the census at that point is the minimum number of beds (22 beds/100,000 population). When patients in the community were least ill, relative to the hospital then hospital bed census is at its optimum (31 beds/100,000) given current resources and technology. In studying specific diagnosis groups with the same methodology the authors found that patients with schizophrenia having the benefit of clozapine for most of the study period had a Q averaged over 7 years that was nearly equal in both hospital and community settings. This explains the perception that tertiary psychiatric hospitals comprised mostly of patients with schizophrenia can downsize significantly. However, affective disorders and "borderline" personality disorders clearly benefit from structured hospital care with specialized experienced staff. We make arguments for the role of the state hospital as a homeostat for the mental health care delivery system. PMID:9509590

Davis, G E; Lowell, W E; Davis, G L

1998-01-01

348

The Degree of Segmental Aneuploidy Measured by Total Copy Number Abnormalities Predicts Survival and Recurrence in Superficial Gastroesophageal Adenocarcinoma  

PubMed Central

Background Prognostic biomarkers are needed for superficial gastroesophageal adenocarcinoma (EAC) to predict clinical outcomes and select therapy. Although recurrent mutations have been characterized in EAC, little is known about their clinical and prognostic significance. Aneuploidy is predictive of clinical outcome in many malignancies but has not been evaluated in superficial EAC. Methods We quantified copy number changes in 41 superficial EAC using Affymetrix SNP 6.0 arrays. We identified recurrent chromosomal gains and losses and calculated the total copy number abnormality (CNA) count for each tumor as a measure of aneuploidy. We correlated CNA count with overall survival and time to first recurrence in univariate and multivariate analyses. Results Recurrent segmental gains and losses involved multiple genes, including: HER2, EGFR, MET, CDK6, KRAS (recurrent gains); and FHIT, WWOX, CDKN2A/B, SMAD4, RUNX1 (recurrent losses). There was a 40-fold variation in CNA count across all cases. Tumors with the lowest and highest quartile CNA count had significantly better overall survival (p?=?0.032) and time to first recurrence (p?=?0.010) compared to those with intermediate CNA counts. These associations persisted when controlling for other prognostic variables. Significance SNP arrays facilitate the assessment of recurrent chromosomal gain and loss and allow high resolution, quantitative assessment of segmental aneuploidy (total CNA count). The non-monotonic association of segmental aneuploidy with survival has been described in other tumors. The degree of aneuploidy is a promising prognostic biomarker in a potentially curable form of EAC. PMID:24454681

Davison, Jon M.; Yee, Melissa; Krill-Burger, J. Michael; Lyons-Weiler, Maureen A.; Kelly, Lori A.; Sciulli, Christin M.; Nason, Katie S.; Luketich, James D.; Michalopoulos, George K.; LaFramboise, William A.

2014-01-01

349

Bandlike transport in pentacene and functionalized pentacene thin films revealed by subpicosecond transient photoconductivity measurements  

E-print Network

signal is observed. The transient photoconductivity in the thin-film samples exhibits a singleBandlike transport in pentacene and functionalized pentacene thin films revealed by subpicosecond in pentacene and functionalized pentacene thin films using time-resolved terahertz pulse spectroscopy

Ostroverkhova, Oksana

350

Experimentally measured thermal transport properties of aluminum–polytetrafluoroethylene nanocomposites with graphene and carbon nanotube additives  

Microsoft Academic Search

Reactive materials such as aluminum (Al) and polytetrafluoroethylene (Teflon) are used for energy generation applications and specifically in ordnance technologies. With the advent of nanotechnology various nano-scale additives have become incorporated into reactive material formulations with the hope of enhanced performance. An important component to the study of energy generation is an examination of energy transport through a reactant matrix.

Keerti Kappagantula; Michelle L. Pantoya

351

In vivo activity of bupropion at the human dopamine transporter as measured by positron emission tomography  

Microsoft Academic Search

BackgroundConverging lines of evidence are consistent with an inhibitory effect of the antidepressant and smoking-cessation aid bupropion on dopamine and norepinephrine reuptake, but the in vivo effects of the drug at the human dopamine transporter (DAT) have not been studied to date. This study employed positron emission tomography (PET) to assess the extent and duration of DAT receptor occupancy by

Susan M Learned-Coughlin; Mats Bergström; Irina Savitcheva; John Ascher; Virginia D Schmith; Bengt Långstrom

2003-01-01

352

Electrical conductivity and transport properties of cement-based materials measured by impedance spectroscopy  

Microsoft Academic Search

The use of Impedance Spectroscopy (IS) as a tool to evaluate the electrical and transport properties of cement-based materials was critically evaluated. Emphasis was placed on determining the efficacy of IS by applying it as a tool to investigate several families of cement-based materials. Also, the functional aspects of electroding and null corrections were also addressed. The technique was found

John David Shane

2000-01-01

353

Cross-shore distribution of longshore sediment transport: comparison between predictive formulas and field measurements  

E-print Network

Facility, U.S. Army Engineer Research and Development Center, 1261 Duck Road, Duck, NC, 27949-4471, USA c and sediment transport from Duck, NC, collected during the DUCK85, SUPERDUCK, and SANDYDUCK field data of swell and storm conditions covered by the field data set. The Engelund­Hansen formula worked reasonably

US Army Corps of Engineers

354

Electrochemical gating of individual single-wall carbon nanotubes observed by electron transport measurements and resonant  

E-print Network

Electrochemical gating of individual single-wall carbon nanotubes observed by electron transport patterned lithographically on top of individual single-wall carbon nanotubes are used to gate the nanotubes and device applications.1,2 The ability to change the resistivity of a semi- conducting single-wall carbon

355

Ocean Waves Measurement and Analysis, Fifth International Symposium WAVES 2005, 3rd-7th, July, 2005. Madrid, Spain Paper number: 197  

E-print Network

Ocean Waves Measurement and Analysis, Fifth International Symposium WAVES 2005, 3rd-7th, July, 2005. Madrid, Spain Paper number: 197 #12;Ocean Waves Measurement and Analysis, Fifth International Symposium WAVES 2005, 3rd-7th, July, 2005. Madrid, Spain #12;Ocean Waves Measurement and Analysis, Fifth

Grilli, Stéphan T.

356

Comparison of Integrated Radiation Transport Models with TEPC Measurements for the Average Quality Factors in Spaceflights  

NASA Technical Reports Server (NTRS)

The purpose of this work is to test our theoretical model for the interpretation of radiation data measured in space. During the space missions astronauts are exposed to the complex field of radiation type and kinetic energies from galactic cosmic rays (GCR), trapped protons, and sometimes solar particle events (SPEs). The tissue equivalent proportional counter (TEPC) is a simple time-dependent approach for radiation monitoring for astronauts on board the International Space Station. Another and a newer approach to Microdosimetry is the use of silicon-on-insulator (SOI) technology launched on the MidSTAR-1 mission in low Earth orbit (LEO). In the radiation protection practice, the average quality factor of a radiation field is defined as a function of linear energy transfer (LET), Q(sub ave)(LET). However, TEPC measures the average quality factor as a function of the lineal energy y, Q(sub ave)(y), defined as the average energy deposition in a volume divided by the average chord length of the volume. Lineal energy, y, deviates from LET due to energy straggling, delta-ray escape or entry, and nuclear fragments produced in the detector volume. Monte Carlo track structure simulation was employed to obtain the response of a TEPC irradiated with charged particle for an equivalent site diameter of 1 micron of wall-less counter. The calculated data of the energy absorption in the wall-less counter were compiled for various y values for several ion types at various discrete projectile energy levels. For the simulation of TEPC response from the mixed radiation environments inside a spacecraft, such as, Space Shuttle and International Space Station, the complete microdosimetric TEPC response, f( y, E, Z), were calculated with the Monte Carlo theoretical results by using the first order Lagrangian interpolation for a monovariate function at a given y value (y = 0.1 keV/micron 5000 keV/micron) at any projectile energy level (E = 0.01 MeV/u to 50,000 MeV/u) of each specific radiation type (Z = 1 to 28). Because the anomalous response has been observed at large event sizes in the experiment due to the escape of energy out of sensitive volume by delta-rays and the entry of delta-rays from the high-density wall into the low-density gas-volume cavity, Monte Carlo simulation was also made for the response of a walled-TEPC with wall thickness 2 mm and density 1 g/cm(exp 3). The radius of cavity was set to 6.35 mm and a gas density 7.874 x 10(exp -5) g/cm(exp 3). The response of the walled- and the wall-less counters were compared. The average quality factor Q(sub ave)(y) for trapped protons on STS-89 demonstrated the good agreement between the model calculations and flight TEPC data as shown. Using an integrated space radiation model (this includes the transport codes HZETRN and BRYNTRN, the quantum nuclear interaction model QMSFRG) and the resultant response distribution functions of walled-TEPC from Monte-Carlo track simulations, we compared model calculations with walled-TEPC measurements from NASA missions in LEO and made predictions for the lunar and the Mars missions. The Q(sub ave)(y) values for the trapped or the solar protons ranged from 1.9-2.5. This over-estimates the Qave(LET) values which ranged from 1.4-1.6. Both quantities increase with shield thickness due to nuclear fragmentation. The Q(sub ave)(LET) for the complete GCR spectra was found to be 3.5-4.5, while flight TEPCs measured 2.9-3.4 for Q(sub ave)(y). The GCR values are decreasing with the shield thickness. Our analysis for a proper interpretation of data supports the use of TEPCs for monitoring space radiation environment.

Kim, Myung-Hee Y.; Nikjoo, Hooshang; Dicello, John F.; Pisacane, Vincent; Cucinotta, Francis A.

2007-01-01

357

Radon measurements in the lower tropical stratosphere - Evidence for rapid vertical transport and dehydration of tropospheric air  

NASA Technical Reports Server (NTRS)

During the tropical experiment of NASA's Stratosphere-Troposphere Exchange Program (STEP), in situ radon and other trace constituent measurements were made aboard a NASA ER-2 high-altitude research aircraft to investigate the mechanisms of irreversible transfers from the troposphere into the tropical stratosphere. Observations made in and downwind of the cirrus shields of three large tropical cyclones and downwind of the cirrus anvil of a large cumulonimbus cloud cluster showed several clear instances of elevated radon activity occurring simultaneously with low total water mixing ratios. These observations are unambiguous evidence of an effective dehydration process, capable of reducing total water vapor mixing ratios to less than 2.5 ppmv, occurring in conjunction with troposphere-to-stratosphere transport and indicate that rapid localized convection, rather than slow regional mean motions, was responsible for the observed transports and associated with the accompanying dehydration. Radon activities measured in regions of active or recent troposphere-to-stratosphere transport were consistent with the 17 pCi/scm mean value needed to support the observed abundance of stratospheric 210 Pb.

Kritz, Mark A.; Rosner, Stefan W.; Kelly, Kenneth K.; Loewenstein, Max; Chan, K. R.

1993-01-01

358

Location - Dependent Coronary Artery Diffusive and Convective Mass Transport Properties of a Lipophilic Drug Surrogate Measured Using Nonlinear Microscopy  

PubMed Central

Purpose Arterial wall mass transport properties dictate local distribution of biomolecules or locally delivered dugs. Knowing how these properties vary between coronary artery locations could provide insight into how therapy efficacy is altered between arterial locations. Methods We introduced an indocarbocyanine drug surrogate to the lumens of left anterior descending and right coronary (LADC; RC) arteries from pigs with or without a pressure gradient. Interstitial fluorescent intensity was measured on live samples with multiphoton microscopy. We also measured binding to porcine coronary SMCs in monoculture. Results Diffusive transport constants peaked in the middle sections of the LADC and RC arteries by 2.09 and 2.04 times, respectively, compared to the proximal and distal segments. There was no statistical difference between the average diffusivity value between LADC and RC arteries. The convection coefficients had an upward trend down each artery, with the RC being higher than the LADC by 3.89 times. Conclusions This study demonstrates that the convective and diffusive transport of lipophilic molecules changes between the LADC and the RC arteries as well as along their length. These results may have important implications in optimizing drug delivery for the treatment of coronary artery disease. PMID:23224981

Keyes, Joseph T.; Simon, Bruce R.; Vande Geest, Jonathan P.

2013-01-01

359

Quantitative Measurement of Colloid and Microbe Transport in Unsaturated Sand at Meso- Scale Using UV-Fluorescence Imaging  

NASA Astrophysics Data System (ADS)

A novel system for direct measurement of colloid mass transport in a sand bed at mm to dm scale using UV- fluorescence (Bridge et al., 2006, ES&T, published online 25-08-06) was extended to quantify 2-D pore water saturation in real time. The system enables high resolution quantification of colloid transport in dynamic unsaturated conditions. Such data under controlled and reproducible conditions in model systems are critical for testing and extending current theory and models for colloid reactive transport in soils, sediments and groundwater. The aqueous phase was a disodium fluorescein (530 nm emission) solution. The colloidal phase was carboxylate-modified 1.9 ?m latex microspheres (612 nm em.). The microbial organism was E.coli K12 stained with DAPI (4',6-diamidino-2-phenylindole, hydrochloride, 460 nm em.). UV excitation peak was 360 nm. Pore saturation between 0.1 and 1 (saturated) during wetting and slow drainage was quantified at sub- millimetre resolution over an area of 200 x 100 mm. Mass balance calculations showed typically less than ±10 % difference between imaged and known total aqueous content. Infiltration experiments were conducted, in which a 10 mL point source plume was injected to a drained sand containing a capillary fringe. Images obtained every 5-20 s showed ±6 % mean deviation between imaged and known aqueous mass input during plume injection at flow rates of 1 and 2 mL/min. Infiltration and movement of colloid and microbial tracers under drained and unsaturated flow conditions at the capillary fringe was quantified relative to the measured saturation field. Colloid and microbial transport results are presented for steady flow experiments at ionic strengths 10-3, 10-2, 10-1 M NaCl in unsaturated conditions and compared to previous experiments conducted in saturated flow fields. Initial results from experiments in pulsed flow fields are also presented. The ability of the technique to measure changes in saturation in real time and at high spatial resolution, with simultaneous measurement of colloid movement makes possible the direct experimental quantification and imaging of instantaneous colloid and microbial transport within dynamic, unsaturated flow fields in optically translucent porous media.

Bridge, J. W.; Puuronen, E.; Banwart, S. A.; Heathwaite, A. L.

2006-12-01

360

Radiation environment at the Moon: Comparisons of transport code modeling and measurements from the CRaTER instrument  

NASA Astrophysics Data System (ADS)

Cosmic Ray Telescope for the Effects of Radiation (CRaTER), an instrument carried on the Lunar Reconnaissance Orbiter spacecraft, directly measures the energy depositions by solar and galactic cosmic radiations in its silicon wafer detectors. These energy depositions are converted to linear energy transfer (LET) spectra. High LET particles, which are mainly high-energy heavy ions found in the incident cosmic ray spectrum, or target fragments and recoils produced by protons and heavier ions, are of particular importance because of their potential to cause significant damage to human tissue and electronic components. Aside from providing LET data useful for space radiation risk analyses for lunar missions, the observed LET spectra can also be used to help validate space radiation transport codes, used for shielding design and risk assessment applications, which is a major thrust of this work. In this work the Monte Carlo transport code HETC-HEDS (High-Energy Transport Code-Human Exploration and Development in Space) is used to estimate LET contributions from the incident primary ions and their charged secondaries produced by nuclear collisions as they pass through the three pairs of silicon detectors. Also in this work, the contributions to the LET of the primary ions and their charged secondaries are analyzed and compared with estimates obtained using the deterministic space radiation code HZETRN 2010, developed at NASA Langley Research Center. LET estimates obtained from the two transport codes are compared with measurements of LET from the CRaTER instrument during the mission. Overall, a comparison of the LET predictions of the HETC-HEDS code to the predictions of the HZETRN code displays good agreement. The code predictions are also in good agreement with the CRaTER LET measurements above 15 keV/µm but differ from the measurements for smaller values of LET. A possible reason for this disagreement between measured and calculated spectra below 15 keV/µm is an inadequate representation of the light ion spectra in HETC-HEDS and HZETRN code calculations. It is also clear from the results of this work that Vavilov distributions need to be incorporated into the HETC-HJEDS code before it will be able to recreate the observed LET spectra measured by the CRaTER instrument.

Porter, Jamie A.; Townsend, Lawrence W.; Spence, Harlan; Golightly, Michael; Schwadron, Nathan; Kasper, Justin; Case, Anthony W.; Blake, John B.; Zeitlin, Cary

2014-06-01

361

Optical refractive synchronization: bidirectional information transport over a single wavelength/single laser for distances > 100 Km: analysis and measurement  

NASA Astrophysics Data System (ADS)

The direction of this paper is to describe the experiments and analytical techniques used by SilkRoad, Inc. for sending 40 GHz of bandwidth, incorporating an eclectic body of data, over a single laser - single fiber over > 100Km of optical fiber using the same wavelength in both directions. The paper will outline the various basic tenets of Optical Refractive Synchronization and the subsequent use of Ellipsometric Phase, based on these tenets, that allows a compilation of CATV, voice, video and SONET data to be transported in both directions without interference between the otpical signals going in both directions over the single fiber. The second portion of the paper will describe the test setup and measurement techniques that were used to validate the analytical models. Pictures of the Spectrum Analyzer data and the subsequent recovery of the eclectic information is then provided for all of the signals that have been transported.

Palmer, James R.

1999-11-01

362

Charge transport in poly(3-hexylthiophene):CdSe nanocrystals hybrid thin films investigated with time-of-flight measurements  

NASA Astrophysics Data System (ADS)

Charge carrier mobilities and transport dispersivity are studied in hybrid films composed of poly(3-hexylthiophene) and CdSe nanocrystals by the time-of-flight method, using a field range of 105-106 V/cm. It is found that charge transport parameters pass through an optimum for 75 wt. % (36 vol. %) of nanocrystals in the polymer matrix, yielding balanced hole and electron mobilities around 10-3 cm2/V s. Changing the nanocrystal shape from spherical to branched increases the intersite coupling disorder in the hybrid whereas changing the surface ligands from stearate/oleylamine to pyridine decreases it. Both these modifications have an impact on the electric field dependence of the measured mobilities.

Couderc, Elsa; Bruyant, Nicolas; Fiore, Angela; Chandezon, Frédéric; Djurado, David; Reiss, Peter; Faure-Vincent, Jérôme

2012-09-01

363

Advances in the measurement and computation of thermal phonon transport properties.  

PubMed

Heat conduction by phonons is a ubiquitous process that incorporates a wide range of physics and plays an essential role in applications ranging from space power generation to LED lighting. Heat conduction has been studied for over two hundred years, yet many of the microscopic details have remained unknown in most crystalline solids, including which phonon-phonon interactions are primarily responsible for thermal resistance and how heat is distributed among the broad thermal spectrum. This lack of knowledge was the result of limitations on the available tools to study heat conduction. However, recent advances in both computation and experiment are enabling an unprecedented microscopic view of thermal transport by phonons in both bulk and nanostructured crystals, from the level of atomic bonding to mesoscopic transport in complex devices. In this topical review, we examine these techniques and the microscopic insights gained into the science and engineering of heat conduction. PMID:25603881

Minnich, A J

2015-02-11

364

Advances in the measurement and computation of thermal phonon transport properties  

NASA Astrophysics Data System (ADS)

Heat conduction by phonons is a ubiquitous process that incorporates a wide range of physics and plays an essential role in applications ranging from space power generation to LED lighting. Heat conduction has been studied for over two hundred years, yet many of the microscopic details have remained unknown in most crystalline solids, including which phonon–phonon interactions are primarily responsible for thermal resistance and how heat is distributed among the broad thermal spectrum. This lack of knowledge was the result of limitations on the available tools to study heat conduction. However, recent advances in both computation and experiment are enabling an unprecedented microscopic view of thermal transport by phonons in both bulk and nanostructured crystals, from the level of atomic bonding to mesoscopic transport in complex devices. In this topical review, we examine these techniques and the microscopic insights gained into the science and engineering of heat conduction.

Minnich, A. J.

2015-02-01

365

One-dimensional deterministic transport in neurons measured by dispersion-relation phase spectroscopy  

PubMed Central

We studied the active transport of intracellular components along neuron processes with a new method developed in our laboratory, dispersion-relation phase spectroscopy. This method is able to quantitatively map spatially the heterogeneous dynamics of the concentration field of the cargos at submicron resolution without the need for tracking individual components. The results in terms of density correlation function reveal that the decay rate is linear in wavenumber, which is consistent with a narrow Lorentzian distribution of cargo velocity. PMID:21862838

Wang, Ru; Wang, Zhuo; Leigh, Joe; Sobh, Nahil; Millet, Larry; Gillette, Martha U.; Levine, Alex J.; Popescu, Gabriel

2011-01-01

366

Understanding charge transport in vacuum deposited Schottky organic solar cells with microsecond transient photocurrent measurements  

NASA Astrophysics Data System (ADS)

Schottky-junction organic solar cells have been a topic of intense research in recent times due to their surprisingly high performance. Some aspects of their device physics are well understood but charge transport in neat-C60 and donor-doped Schottky junction OSCs has not been studied in detail so far. In this study, charge transport in neat-C60 OSCs is examined by studying the performance of these OSCs as a function of C60 active layer thickness. Surprisingly, the fillfactor of the neat-C60 Schottky OSC does not degrade for layer thicknesses between 20 nm - 80 nm indicating that charge transport is not an issue. However, the short-circuit current decreases significantly due to a reduction in the builtin voltage. The dissociation of excitons formed in C60 aggregates is preferentially reduced. Devices with thicker C60 layers and consequently, higher C60 aggregation, were found to have greater recombination. Finally, charge mobility in C60 films with aggregates is found to be lower than charge mobility in films with little to no aggregation.

Sutty, Sibi; Williams, Graeme; Aziz, Hany

2014-10-01

367

Toward the definition and measurement of the mental workload of transport pilots  

E-print Network

This report describes work performed in the first year of a continuing research project aimed at developing useful methods for measuring the workload of pilots operating aircraft in the ATC system. Good methods of measuring ...

Sheridan, Thomas B.

1979-01-01

368

Polymorphic variation in choline transporter gene (CHT1) is associated with early, subclinical measures of carotid atherosclerosis in humans  

PubMed Central

Atherosclerosis is a heritable trait with little known about specific genetic influences on preclinical measures of plaque formation. Based on relations of parasympathetic-cholinergic function to atherosclerosis and to a choline transporter gene [CHT1 (G/T)] polymorphism, we investigated whether the same allelic variant predicts variation in carotid intima-media thickness (IMT) and plaque formation. Carotid IMT and plaque occurrence as well as genotyping for the CHT1 (G/T) variant were measured in a sample (N = 264) of generally healthy adults (age 30–55) of European ancestry. CHT1 GG homozygotes had greater IMT (P < 0.005) and plaque occurrence (P < 0.020) than T allele carriers. This is the first study showing polymorphic variation in the CHT1 gene to predict early, subclinical measures of carotid atherosclerosis which may aid in understanding cholinergic-vagal processes potentially underlying atherosclerotic risk. PMID:21337021

Linder, Katherine J.; Muldoon, Matthew F.; Sutton-Tyrrell, Kimberly; Kline, Christopher; Shrader, Catherine J.; Lawrence, Elizabeth C.; Ferrell, Robert E.; Manuck, Stephen B.

2012-01-01

369

3. Formalizing and Modeling the World "When you can measure what you are speaking of and express it in numbers you know that on which  

E-print Network

it in numbers you know that on which you are discoursing. But if you cannot measure it and express it in numbers English Dictionary, which defines information as "the action of informing; formation or molding, reader, interpretant, spectator, investigator, computer, cell, etc. The SIGN has been called the signal

Menczer, Filippo

370

Thermal Transport Characteristics of Human Skin Measured In Vivo Using Ultrathin Conformal Arrays of Thermal Sensors and Actuators  

PubMed Central

Measurements of the thermal transport properties of the skin can reveal changes in physical and chemical states of relevance to dermatological health, skin structure and activity, thermoregulation and other aspects of human physiology. Existing methods for in vivo evaluations demand complex systems for laser heating and infrared thermography, or they require rigid, invasive probes; neither can apply to arbitrary regions of the body, offers modes for rapid spatial mapping, or enables continuous monitoring outside of laboratory settings. Here we describe human clinical studies using mechanically soft arrays of thermal actuators and sensors that laminate onto the skin to provide rapid, quantitative in vivo determination of both the thermal conductivity and thermal diffusivity, in a completely non-invasive manner. Comprehensive analysis of measurements on six different body locations of each of twenty-five human subjects reveal systematic variations and directional anisotropies in the characteristics, with correlations to the thicknesses of the epidermis (EP) and stratum corneum (SC) determined by optical coherence tomography, and to the water content assessed by electrical impedance based measurements. Multivariate statistical analysis establishes four distinct locations across the body that exhibit different physical properties: heel, cheek, palm, and wrist/volar forearm/dorsal forearm. The data also demonstrate that thermal transport correlates negatively with SC and EP thickness and positively with water content, with a strength of correlation that varies from region to region, e.g., stronger in the palmar than in the follicular regions. PMID:25658947

Webb, R. Chad; Pielak, Rafal M.; Bastien, Philippe; Ayers, Joshua; Niittynen, Juha; Kurniawan, Jonas; Manco, Megan; Lin, Athena; Cho, Nam Heon; Malyrchuk, Viktor; Balooch, Guive; Rogers, John A.

2015-01-01

371

A Fluorescence Recovery After Photobleaching (FRAP) Technique for the Measurement of Solute Transport Across Surfactant-Laden Interfaces  

NASA Technical Reports Server (NTRS)

The technique of Fluorescence Recovery After Photobleaching (FRAP) has been applied to the measurement of interfacial transport in two-phase systems. FRAP exploits the loss of fluorescence exhibited by certain fluorophores when over-stimulated (photobleached), so that a two-phase system, originally at equilibrium, can be perturbed without disturbing the interface by strong light from an argon-ion laser and its recovery monitored by a microscope-mounted CCD camera as it relaxes to a new equilibrium. During this relaxation, the concentration profiles of the probe solute are measured on both sides of the interface as a function of time, yielding information about the transport characteristics of the system. To minimize the size of the meniscus between the two phases, a photolithography technique is used to selectively treat the glass walls of the cell in which the phases are contained. This allows concentration measurements to be made very close to the interface and increases the sensitivity of the FRAP technique.

Browne, Edward P.; Hatton, T. Alan

1996-01-01

372

A nu-space for image correlation spectroscopy: characterization and application to measure protein transport in live cells  

NASA Astrophysics Data System (ADS)

We introduce a new generalized theoretical framework for image correlation spectroscopy (ICS). Using this framework, we extend the ICS method in time-frequency (?, nu) space to map molecular flow of fluorescently tagged proteins in individual living cells. Even in the presence of a dominant immobile population of fluorescent molecules, nu-space ICS (nICS) provides an unbiased velocity measurement, as well as the diffusion coefficient of the flow, without requiring filtering. We also develop and characterize a tunable frequency-filter for spatio-temporal ICS (STICS) that allows quantification of the density, the diffusion coefficient and the velocity of biased diffusion. We show that the techniques are accurate over a wide range of parameter space in computer simulation. We then characterize the retrograde flow of adhesion proteins (?6- and ?L?2-GFP integrins and mCherry-paxillin) in CHO.B2 cells plated on laminin and intercellular adhesion molecule 1 (ICAM-1) ligands respectively. STICS with a tunable frequency filter, in conjunction with nICS, measures two new transport parameters, the density and transport bias coefficient (a measure of the diffusive character of a flow/biased diffusion), showing that molecular flow in this cell system has a significant diffusive component. Our results suggest that the integrin-ligand interaction, along with the internal myosin-motor generated force, varies for different integrin-ligand pairs, consistent with previous results.

Potvin-Trottier, Laurent; Chen, Lingfeng; Horwitz, Alan Rick; Wiseman, Paul W.

2013-08-01

373

Thermal transport characteristics of human skin measured in vivo using ultrathin conformal arrays of thermal sensors and actuators.  

PubMed

Measurements of the thermal transport properties of the skin can reveal changes in physical and chemical states of relevance to dermatological health, skin structure and activity, thermoregulation and other aspects of human physiology. Existing methods for in vivo evaluations demand complex systems for laser heating and infrared thermography, or they require rigid, invasive probes; neither can apply to arbitrary regions of the body, offers modes for rapid spatial mapping, or enables continuous monitoring outside of laboratory settings. Here we describe human clinical studies using mechanically soft arrays of thermal actuators and sensors that laminate onto the skin to provide rapid, quantitative in vivo determination of both the thermal conductivity and thermal diffusivity, in a completely non-invasive manner. Comprehensive analysis of measurements on six different body locations of each of twenty-five human subjects reveal systematic variations and directional anisotropies in the characteristics, with correlations to the thicknesses of the epidermis (EP) and stratum corneum (SC) determined by optical coherence tomography, and to the water content assessed by electrical impedance based measurements. Multivariate statistical analysis establishes four distinct locations across the body that exhibit different physical properties: heel, cheek, palm, and wrist/volar forearm/dorsal forearm. The data also demonstrate that thermal transport correlates negatively with SC and EP thickness and positively with water content, with a strength of correlation that varies from region to region, e.g., stronger in the palmar than in the follicular regions. PMID:25658947

Webb, R Chad; Pielak, Rafal M; Bastien, Philippe; Ayers, Joshua; Niittynen, Juha; Kurniawan, Jonas; Manco, Megan; Lin, Athena; Cho, Nam Heon; Malyrchuk, Viktor; Balooch, Guive; Rogers, John A

2015-01-01

374

Wind Tunnel Measured Effects on a Twin-Engine Short-Haul Transport Caused by Simulated Ice Accretions  

NASA Technical Reports Server (NTRS)

A series of wind tunnel tests were conducted to assess the effects of leading edge ice contamination upon the performance of a short-haul transport. The wind tunnel test was conducted in the NASA Langley 14 by 22 foot facility. The test article was a 1/8 scale twin-engine short-haul jet transport model. Two separate leading edge ice contamination configurations were tested in addition to the uncontaminated baseline configuration. Several aircraft configurations were examined including various flap and slat deflections, with and without landing gear. Data gathered included force measurements via an internal six-component force balance, pressure measurements through 700 electronically scanned wing pressure ports, and wing surface flow visualization measurements. The artificial ice contamination caused significant performance degradation and caused visible changes demonstrated by the flow visualization. The data presented here is just a portion of the data gathered. A more complete data report is planned for publication as a NASA Technical Memorandum and data supplement.

Reehorst, Andrew; Potapczuk, Mark; Ratvasky, Thomas; Laflin, Brenda Gile

1996-01-01

375

Temporal and spatial effects of ablation plume on number density distribution of droplets in an aerosol measured by laser-induced breakdown  

SciTech Connect

We proposed and experimentally demonstrated a novel method of evaluating the number density of droplets in an aerosol by laser-induced breakdown. The number density of droplets is evaluated from the volume in which the laser intensity exceeds the breakdown threshold intensity for droplets, and the number of droplets in this volume, which is evaluated by the experimentally observed breakdown probability. This measurement method requires a large number of laser shots for not only precise measurement but also highly temporally and spatially resolved density distribution in aerosol. Laser ablation plumes ejected from liquid droplets generated by breakdown disturb the density around the measurement points. Therefore, the recovery time of the density determines the maximum repetition rate of the probe laser irradiating a fixed point. The expansion range of the ablation plume determines the minimum distance at which the measurement points are unaffected by a neighboring breakdown when multiple laser beams are simultaneously irradiated. These laser irradiation procedures enable the measurement of the number density distribution of droplets in an aerosol at a large number of points within a short measurement time.

Yashiro, H.; Kakehata, M. [Electronics and Photonics Research Institute (ESPRIT), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

2013-05-07

376

Three-dimensional shape measurement system applied to superficial inspection of non-metallic pipes for the hydrocarbons transport  

NASA Astrophysics Data System (ADS)

Three-dimensional shape measurement is a subject that consistently produces high scientific interest and provides information for medical, industrial and investigative applications, among others. In this paper, it is proposed to implement a three-dimensional (3D) reconstruction system for applications in superficial inspection of non-metallic pipes for the hydrocarbons transport. The system is formed by a CCD camera, a video-projector and a laptop and it is based on fringe projection technique. System functionality is evidenced by evaluating the quality of three-dimensional reconstructions obtained, which allow observing the failures and defects on the study object surface.

Arciniegas, Javier R.; González, Andrés. L.; Quintero, L. A.; Contreras, Carlos R.; Meneses, Jaime E.

2014-05-01

377

Note: Adhesive stamp electrodes using spider silk masks for electronic transport measurements of supra-micron sized samples  

NASA Astrophysics Data System (ADS)

A procedure for fabricating adhesive stamp electrodes based on gold coated adhesive tape used to measure electronic transport properties of supra-micron samples in the lateral range 10-100 ?m and thickness >1 ?m is described. The electrodes can be patterned with a ˜4 ?m separation by metal deposition through a mask using Nephila clavipes spider dragline silk fibers. Ohmic contact is made by adhesive lamination of a sample onto the patterned electrodes. The performance of the electrodes with temperature and magnetic field is demonstrated for the quasi-one-dimensional organic conductor (TMTSF)2PF6 and single crystal graphite, respectively.

Steven, E.; Jobiliong, E.; Eugenio, P. M.; Brooks, J. S.

2012-04-01

378

Low-Speed Stability-and-Control and Ground-Effects Measurements on the Industry Reference High Speed Civil Transport  

NASA Technical Reports Server (NTRS)

As a part of a national effort to develop an economically feasible High Speed Civil Transport (HSCT), a single configuration has been accepted as the testing baseline by the organizations working in the High Speed Research (HSR) program. The configuration is based on a design developed by the Boeing Company and is referred to as the Reference H (Ref H). The data contained in this report are low-speed stability-and-control and ground-effect measurements obtained on a 0.06 scale model of the Ref H in a subsonic tunnel.

Kemmerly, Guy T.; Campbell, Bryan A.; Banks, Daniel W.; Yaros, Steven F.

1999-01-01

379

Beam measurements on the H- source and Low Energy Beam Transport system for the Spallation Neutron Source  

SciTech Connect

The ion source and Low Energy Beam Transport section of the front-end systems presently being built by Berkeley Lab are required to provide 50 mA of H - beam current at 6% duty factor (1 ms pulses at 60 Hz) with a normalized rms emittance of less than 0.20 p-mm-mrad. Experimental results, including emittance, chopping, and steering measurements, on the performance of the ion source and LEBT system operated at the demanded beam parameters will be discussed.

Thomae, R.; Gough, R.; Keller, R.; Leung, K.N.; Schenkel, T.; Aleksandrov, A.; Stockli, M.; Welton, R.

2001-09-01

380

Calorimetric AC loss measurement of MgB2 superconducting tape in an alternating transport current and direct magnetic field  

NASA Astrophysics Data System (ADS)

Applications of MgB2 superconductors in electrical engineering have been widely reported, and various studies have been made to define their alternating current (AC) losses. However, studies on the transport losses with an applied transverse DC magnetic field have not been conducted, even though this is one of the favored conditions in applications of practical MgB2 tapes. Methods and techniques used to characterize and measure these losses have so far been grouped into ‘electrical’ and ‘calorimetric’ approaches with external conditions set to resemble the application conditions. In this paper, we present a new approach to mounting the sample and employ the calorimetric method to accurately determine the losses in the concurrent application of AC transport current and DC magnetic fields that are likely to be experienced in practical devices such as generators and motors. This technique provides great simplification compared to the pickup coil and lock-in amplifier methods and is applied to a long length (˜10 cm) superconducting tape. The AC loss data at 20 and 30 K will be presented in an applied transport current of 50 Hz under external DC magnetic fields. The results are found to be higher than the theoretical predictions because of the metallic fraction of the tape that contributes quite significantly to the total losses. The data, however, will allow minimization of losses in practical MgB2 coils and will be used in the verification of numerical coil models.

See, K. W.; Xu, X.; Horvat, J.; Cook, C. D.; Dou, S. X.

2012-11-01

381

Triaxial creep measurements on rock salt from the Jennings dome, Louisiana, borehole LA-1, core {number_sign}8  

SciTech Connect

Tejas Power Company requested that facilities in the Rock Mechanics Laboratory at Sandia National Laboratories be used to assess the time-dependent properties of rock salt from the Jennings dome in Acadia Parish, Louisiana. Nominally 2.5-inch diameter slat core from borehole LA-1, core 8 (depth 3924.8 to 3837.8 ft; 1196.8--1197.1 m) was provided to accomplish two tasks: (1) Using the smallest possible number of experiments, evaluate the tendency of Jennings salt to undergo time-dependent deformation (creep) under constant applied stresses, and compare the creep of Jennings salt with creep data for rock salt from other locations. (2) Assess the applicability of published laboratory-derived creep properties for rock salt from several bedded and domal sites in finite element analyses concerning the design of new gas storage caverns in the Jennings dome. The characterization of Jennings salt followed the same strategy that was applied in earlier laboratory experiments on core from the Moss Bluff dome near Houston, Texas. This report summarizes the relevant details of five creep experiments on a sample from depth 3927.5 ft, the results obtained, and how these results compared with laboratory creep measurements gathered on rock salt from other locations including the West Hackberry, Bryan Mound and Moss Bluff domes. The report also considers the estimates of specific creep parameters commonly used in numerical engineering design analyses.

Wawersik, W.R.; Zimmerer, D.J.

1994-05-01

382

In situ optical measurement of charge transport dynamics in organic photovoltaics.  

PubMed

We present a novel experimental approach which allows extraction of both spatial and temporal information on charge dynamics in organic solar cells. Using the wavelength dependence of the photonic structure in these devices, we monitor the change in spatial overlap between the photogenerated hole distribution and the optical probe profile as a function of time. In a model system we find evidence for a buildup of the photogenerated hole population close to the hole-extracting electrode on a nanosecond time scale and show that this can limit charge transport through space-charge effects under operating conditions. PMID:25585168

Chow, Philip C Y; Bayliss, Sam L; Lakhwani, Girish; Greenham, Neil C; Friend, Richard H

2015-02-11

383

An approach for measuring the thermal conductivity of in situ foamed insulated pipe transporting liquid nitrogen  

NASA Astrophysics Data System (ADS)

The thermal conductivity of three foamed pipes has been tested for the development of liquid nitrogen transmission pipelines. By establishing a function between evaporation rate and thermal conductivity, we obtain effective thermal conductivity without destroying pipes. The comparison between our test and test coupons shows that this test device is reliable and could be a standard test for checking insulation properties of in situ foamed pipes transporting liquid nitrogen. The scientific principles, system design, experimental results and effect factors of the test are presented in this paper.

Xu, Dong; Wu, Heng; Liu, Huiming; Gong, Linghui; Xu, Xiangdong; Li, L. F.

2012-06-01

384

Intracellular Drug Concentrations and Transporters: Measurement, Modeling, and Implications for the Liver  

PubMed Central

Intracellular concentrations of drugs and metabolites are often important determinants of efficacy, toxicity, and drug interactions. Hepatic drug distribution can be affected by many factors, including physicochemical properties, uptake/efflux transporters, protein binding, organelle sequestration, and metabolism. This white paper highlights determinants of hepatocyte drug/metabolite concentrations and provides an update on model systems, methods, and modeling/simulation approaches used to quantitatively assess hepatocellular concentrations of molecules. The critical scientific gaps and future research directions in this field are discussed. PMID:23588320

Chu, X; Korzekwa, K; Elsby, R; Fenner, K; Galetin, A; Lai, Y; Matsson, P; Moss, A; Nagar, S; Rosania, GR; Bai, JPF; Polli, JW; Sugiyama, Y; Brouwer, KLR

2013-01-01

385

Source evaluation of aerosols measured during the Indian Ocean Experiment using combined chemical transport and back trajectory modeling  

NASA Astrophysics Data System (ADS)

This work presents an analysis of aerosol measurements made during the Oceanographic Research Vessel Sagar Kanya cruise of January-March 1999, in the Indian Ocean Experiment intensive field phase (INDOEX-IFP), with regard to the aerosol chemical constituents and identification of source regions of their origin. This is done through a hybrid approach which uses an Eulerian forward transport calculation in a general circulation model (GCM) with region-tagged emissions along with an analysis of Lagrangian back trajectories and emission inventory information, for overlapping time periods. Back trajectory analysis showed that the ship was mainly influenced by air masses from the Indo-Gangetic plain, central India, or south India during the early part of its cruise with the GCM-predicted aerosol species composed of mainly sulfate and organic matter, whereas dust species dominated during its cruise in late February and early March over the Arabian Sea when the ship was influenced by air masses from Africa-west Asia or northwest India. However, a typical clean marine aerosol dominated by sea salt was encountered during February when the ship cruised in the tropical Indian Ocean and was mostly influenced by marine air masses. The high aerosol optical depth was due to roughly equal parts of organic matter and sulfate. Region-tagged GCM estimates showed the presence of distinct transport at surface and higher layers for, e.g., DOY 56-61 and 65-70, indicating strong signals of emissions of black carbon, organic matter, and sulfate originating in central and northwest India, whereas elevated transport channels of black carbon and organic matter from Africa-west Asia. This is consistent with the back trajectory analysis and in corroboration with INDOEX measurement studies which observed different aerosol properties from aircraft and ship attributed to different transport pathways in surface and elevated flows. However, back trajectory analysis is not sufficient to evaluate the major source regions contributing to the transported aerosol. The fractional contribution of a source region also depended upon the emission flux from the region and its proximity to the receptor domain.

Verma, S.; Venkataraman, C.; Boucher, O.; Ramachandran, S.

2007-06-01

386

Heterogeneity in hydraulic conductivity and its role on the macroscale transport of a solute plume: From measurements to a practical application of stochastic flow and transport theory  

NASA Astrophysics Data System (ADS)

The spatial variability of hydraulic conductivity in a shallow unconfined aquifer located at North Bay, Ontario, composed of glacial-lacustrine and glacial-fluvial sands, is examined in exceptional detail and characterized geostatistically. A total of 1878 permeameter measurements were performed at 0.05 m vertical intervals along cores taken from 20 boreholes along two intersecting transect lines. Simultaneous three-dimensional (3-D) fitting of Ln(K) variogram data to an exponential model yielded geostatistical parameters for the estimation of bulk hydraulic conductivity and solute dispersion parameters. The analysis revealed a Ln(K) variance equal to about 2.0 and 3-D anisotropy of the correlation structure of the heterogeneity (?1, ?2, and ?3 equal to 17.19, 7.39, and 1.0 m, respectively). Effective values of the hydraulic conductivity tensor and the value of the longitudinal macrodispersivity were calculated using the theoretical expressions of Gelhar and Axness (1983). The magnitude of the longitudinal macrodispersivity is reasonably consistent with the observed degree of longitudinal dispersion of the landfill plume along the principal path of migration. Variably saturated 3-D flow modeling using the statistically derived effective hydraulic conductivity tensor allowed a reasonably close prediction of the measured water table and the observed heads at various depths in an array of piezometers. Concomitant transport modeling using the calculated longitudinal macrodispersivity reasonably predicted the extent and migration rates of the observed contaminant plume that was monitored using a network of multilevel samplers over a period of about 5 years. It was further demonstrated that the length of the plume is relatively insensitive to the value of the longitudinal macrodispersivity under the conditions of a steady flow in 3-D and constant source strength. This study demonstrates that the use of statistically derived parameters based on stochastic theories results in reliable large-scale 3-D flow and transport models for complex hydrogeological systems. This is in agreement with the conclusions reached by Sudicky (1986) at the site of an elaborate tracer test conducted in the aquifer at the Canadian Forces Base Borden.

Sudicky, E. A.; Illman, W. A.; Goltz, I. K.; Adams, J. J.; McLaren, R. G.

2010-01-01

387

Smoking status and the human dopamine transporter variable number of tandem repeats (VNTR) polymorphism: failure to replicate and finding that never-smokers may be different.  

PubMed

Cigarette smoking, like many addictive behaviors, has been shown to have a genetic component. The dopamine transporter (DAT) gene (SLC6A3) encodes a protein that regulates synaptic levels of dopamine in the brain and is a candidate gene for addictive behaviors. We have collected smoking information from a national probability sample of 3383 adult volunteers contacted via a random-digit dialing telephone interview. A subset of individuals provided DNA from cheek swabs returned via the mail for subsequent genetic analysis of self-reported smoking behavior. DNA samples were genotyped at a variable number of tandem repeats (VNTR) polymorphism in the 3'-untranslated region of the DAT gene. If we classify smokers as non- (<100 cigarettes), former and current, we fail to replicate both Lerman et al. (Health Psychology 18:14-20, 1999) and Sabol et al. (Health Psychology 18:7-13, 1999) and support the absence of effects found by Jorm et al. (American Journal of Medical Genetics (Neuropsychiatric Genetics) 96:331-334, 2000). When we distinguish between never-smokers (no cigarettes ever) and non-smokers (1-99 in lifetime), we find a reliable trend essentially in the opposite direction from Lerman et al. (1999), with the 10-copy allele being more frequent in never-smokers. Biobehavioral research on cigarette smoking should distinguish between never- and non-smokers. We have also developed an improved set of polymerase chain reaction conditions to increase the frequency of successful amplification of DAT'sw VNTR, which is a long, G+C-rich repeat. PMID:12215242

Vandenbergh, David J; Bennett, Christina J; Grant, Michael D; Strasser, Andrew A; O'Connor, Richard; Stauffer, Rebecca L; Vogler, George P; Kozlowski, Lynn T

2002-08-01

388

Informing Aerosol Transport Models With Satellite Multi-Angle Aerosol Measurements  

NASA Technical Reports Server (NTRS)

As the aerosol products from the NASA Earth Observing System's Multi-angle Imaging SpectroRadiometer (MISR) mature, we are placing greater focus on ways of using the aerosol amount and type data products, and aerosol plume heights, to constrain aerosol transport models. We have demonstrated the ability to map aerosol air-mass-types regionally, and have identified product upgrades required to apply them globally, including the need for a quality flag indicating the aerosol type information content, that varies depending upon retrieval conditions. We have shown that MISR aerosol type can distinguish smoke from dust, volcanic ash from sulfate and water particles, and can identify qualitative differences in mixtures of smoke, dust, and pollution aerosol components in urban settings. We demonstrated the use of stereo imaging to map smoke, dust, and volcanic effluent plume injection height, and the combination of MISR and MODIS aerosol optical depth maps to constrain wildfire smoke source strength. This talk will briefly highlight where we stand on these application, with emphasis on the steps we are taking toward applying the capabilities toward constraining aerosol transport models, planet-wide.

Limbacher, J.; Patadia, F.; Petrenko, M.; Martin, M. Val; Chin, M.; Gaitley, B.; Garay, M.; Kalashnikova, O.; Nelson, D.; Scollo, S.

2011-01-01

389

Photon-number distributions of twin beams generated in spontaneous parametric down-conversion and measured by an intensified CCD camera  

E-print Network

The measurement of photon-number statistics of fields composed of photon pairs, generated in spontaneous parametric down-conversion and detected by an intensified CCD camera is described. Final quantum detection efficiencies, electronic noises, finite numbers of detector pixels, transverse intensity spatial profiles of the detected beams as well as losses of single photons from a pair are taken into account in a developed general theory of photon-number detection. The measured data provided by an iCCD camera with single-photon detection sensitivity are analyzed along the developed theory. Joint signal-idler photon-number distributions are recovered using the reconstruction method based on the principle of maximum likelihood. The range of applicability of the method is discussed. The reconstructed joint signal-idler photon-number distribution is compared with that obtained by a method that uses superposition of signal and noise and minimizes photoelectron entropy. Statistics of the reconstructed fields are identified to be multi-mode Gaussian. Elements of the measured as well as the reconstructed joint signal-idler photon-number distributions violate classical inequalities. Sub-shot-noise correlations in the difference of the signal and idler photon numbers as well as partial suppression of odd elements in the distribution of the sum of signal and idler photon numbers are observed.

Jan Perina Jr; Ondrej Haderka; Martin Hamar; Vaclav Michalek

2012-02-07

390

Commercial apparatus for measuring thermal transport properties from 1.9 to 390 kelvin  

Microsoft Academic Search

We have developed an instrument which simultaneously measures the thermal conductivity kappa, Seebeck coefficient alpha, and electrical resistivity rho of a sample, thereby determining the thermoelectric figure of merit Z = alpha ^2 \\/ rho kappa. A Quantum Design Physical Property Measurement System (PPMS) provides the temperature control from 1.9 - 390 K and applied magnetic fields of up to

N. R. Dilley; R. C. Black; L. Montes; A. Wilson; M. B. Simmonds

2001-01-01

391

Methanol transport through Nafion membranes: Electro-osmotic drag effects on potential step measurements  

Microsoft Academic Search

This paper describes methanol flux measurements across Nafion, 1100 equivalent weight membranes under conditions of a direct methanol fuel cell but in which methanol is completely electro-oxidized on the opposite side in an inert atmosphere at sufficiently high electrode potential. Both the diffusion coefficient and the methanol concentration in the membrane were determined from the measured transient limiting current density

Xiaoming Ren; Thomas E. Springer; Thomas A. Zawodzinski; Shimshon Gottesfeld

2000-01-01

392

DESIGN AND IMPLEMENTATION OF A TRANSPORTABLE SYSTEM FOR DIRECT MEASUREMENT OF DRY DEPOSITION FLUXES  

EPA Science Inventory

Dry deposition of air pollutants is expensive and difficult to measure. icks et al. (1985) proposed the dry deposition inferential model determines dry deposition fluxes as the product of a measured concentration and a modeled deposition velocity. eposition velocity is calculated...

393

Erosion of upland hillslope soil organic carbon: Coupling field measurements with a sediment transport model  

E-print Network

Erosion of upland hillslope soil organic carbon: Coupling field measurements with a sediment soil C measurements to quantify the erosion and temporal storage of soil organic carbon (SOC) within perturbation (Tennessee Valley (TV)) versus clay-rich soil creep (Black Diamond (BD)). The average SOC erosion

Heimsath, Arjun M.

394

Measured Local Heat Transport in Turbulent Rayleigh-Benard Convection X.-D. Shang,1  

E-print Network

September 2002; published 20 February 2003) Local convective heat flux in turbulent thermal convection filled with water. It is found that fluctuations of the vertical heat flux are highly intermittent heat is trans- ported vertically through a convection cell [1­3]. A large number of global heat

Tong, Penger

395

Detector LifeCycle Costs and Considerations Mobility Measurement in Urban Transportation Pooled Fund Study  

E-print Network

element, as well as overall costs (including Year 1, 5year lifecycle cost, 10year lifecycle cost) per mile and for a given segment length. Development of such a tool includes a number of assumptions of the Year 1 costs, 5year lifecycle cost, and 10year lifecycle cost. Costs are shown in table and graphic

396

Measurement and prediction of particle entrainment and conveying: Effect of particle characteristics, mass loading, and Reynolds number  

Microsoft Academic Search

Pneumatic conveying is a widely used method of transporting particles in industrial processes. Two of the most important parameters needed to effectively design conveying lines are the conveying gas velocity and pressure drop. Estimation of pickup velocity, defined as the fluid velocity required to pick up a particle from rest, is a suitable way to approximate the minimum conveying gas

Kimberly Hayden Henthorn

2004-01-01

397

Inhalable particulate matter and mitochondrial DNA copy number in highly exposed individuals in Beijing, China: a repeated-measure study  

PubMed Central

Background Mitochondria are both a sensitive target and a primary source of oxidative stress, a key pathway of air particulate matter (PM)-associated diseases. Mitochondrial DNA copy number (MtDNAcn) is a marker of mitochondrial damage and malfunctioning. We evaluated whether ambient PM exposure affects MtDNAcn in a highly-exposed population in Beijing, China. Methods The Beijing Truck Driver Air Pollution Study was conducted shortly before the 2008 Beijing Olympic Games (June 15-July 27, 2008) and included 60 truck drivers and 60 office workers. Personal PM2.5 and elemental carbon (EC, a tracer of traffic particles) were measured during work hours using portable monitors. Post-work blood samples were obtained on two different days. Ambient PM10 was averaged from 27 monitoring stations in Beijing. Blood MtDNAcn was determined by real-time PCR and examined in association with particle levels using mixed-effect models. Results In all participants combined, MtDNAcn was negatively associated with personal EC level measured during work hours (?=?0.059, 95% CI: -0.011; -0.0006, p=0.03); and 5-day (?=?0.017, 95% CI: -0.029;-0.005, p=0.01) and 8-day average ambient PM10 (?=?0.008, 95% CI: -0.043; -0.008, p=0.004) after adjusting for possible confounding factors, including study groups. MtDNAcn was also negatively associated among office workers with EC (?=?0.012, 95% CI: -0.022;-0.002, p=0.02) and 8-day average ambient PM10 (?=?0.030, 95% CI: -0.051;-0.008, p=0.007). Conclusions We observed decreased blood MtDNAcn in association with increased exposure to EC during work hours and recent ambient PM10 exposure. Our results suggest that MtDNAcn may be influenced by particle exposures. Further studies are required to determine the roles of MtDNAcn in the etiology of particle-related diseases. PMID:23628000

2013-01-01

398

From computing with numbers to computing with words-from manipulation of measurements to manipulation of perceptions  

NASA Astrophysics Data System (ADS)

Computing, in its usual sense, is centered on manipulation of numbers and symbols. In contrast, computing with words, or CW for short, is a methodology in which the objects of computation are words and propositions drawn from a natural language, e.g., small, large, far, heavy, not very likely, the price of gas is low and declining, Berkeley is near San Francisco, it is very unlikely that there will be a significant increase in the price of oil in the near future, etc. Computing with words is inspired by the remarkable human capability to perform a wide variety of physical and mental tasks without any measurements and any computations. Familiar examples of such tasks are parking a car, driving in heavy traffic, playing golf, riding a bicycle, understanding speech and summarizing a story. Underlying this remarkable capability is the brain's crucial ability to manipulate perceptions-perceptions of distance, size, weight, color, speed, time, direction, force, number, truth, likelihood and other characteristics of physical and mental objects. Manipulation of perceptions plays a key role in human recognition, decision and execution processes. As a methodology, computing with words provides a foundation for a computational theory of perceptions-a theory which may have an important bearing on how humans make-and machines might make-perception-based rational decisions in an environment of imprecision, uncertainty and partial truth. A basic difference between perceptions and measurements is that, in general, measurements are crisp whereas perceptions are fuzzy. One of the fundamental aims of science has been and continues to be that of progressing from perceptions to measurements. Pursuit of this aim has led to brilliant successes. We have sent men to the moon; we can build computers that are capable of performing billions of computations per second; we have constructed telescopes that can explore the far reaches of the universe; and we can date the age of rocks that are millions of years old. But alongside the brilliant successes stand conspicuous underachievements and outright failures. We cannot build robots which can move with the agility of animals or humans; we cannot automate driving in heavy traffic; we cannot translate from one language to another at the level of a human interpreter; we cannot create programs which can summarize non-trivial stories; our ability to model the behavior of economic systems leaves much to be desired; and we cannot build machines that can compete with children in the performance of a wide variety of physical and cognitive tasks. It may be argued that underlying the underachivements and failures is the unavailability of a methodology for reasoning and computing with perceptions rather than measurements. An outline of such a methodology-referred to as a computational theory of perceptions-is presented in this paper. The computational theory of perceptions, or CTP for short, is based on the methodology of computing with words (CW). In CTP, words play the role of labels of perceptions and, more generally, perceptions are expressed as propositions in a natural language. CW-based techniques are employed to translate propositions expressed in a natural language into what is called the Generalized Constraint Language (GCL). In this language, the meaning of a proposition is expressed as a generalized constraint, X isr R, where X is the constrained variable, R is the constraining relation and isr is a variable copula in which r is a variable whose value defines the way in which R constrains X. Among the basic types of constraints are: possibilistic, veristic, probabilistic, random set, Pawlak singing then the emphasis is put on the action aspect, while if we want to say that the singing is loud then the emphasis is on the sound, which is treated as a thing since one hears it. The crucial point is that one seems to be forced to make such a distinction, as assists the determination of structure, but the origin of this distinction is probably related to the different ways actions and objects are represented

Zadeh, Lotfi A.

2001-06-01

399

Apparatus and method for detecting and measuring changes in linear relationships between a number of high frequency signals  

DOEpatents

An electronic measurement circuit is disclosed for high speed comparison of the relative amplitudes of a predetermined number of electrical input signals independent of variations in the magnitude of the sum of the signals. The circuit includes a high speed electronic switch that is operably connected to receive on its respective input terminals one of said electrical input signals and to have its common terminal serve as an input for a variable-gain amplifier-detector circuit that is operably connected to feed its output to a common terminal of a second high speed electronic switch. The respective terminals of the second high speed electronic switch are operably connected to a plurality of integrating sample and hold circuits, which in turn have their outputs connected to a summing logic circuit that is operable to develop first, second and third output voltages, the first output voltage being proportional to a predetermined ratio of sums and differences between the compared input signals, the second output voltage being proportional to a second summed ratio of predetermined sums and differences between said input signals, and the third output voltage being proportional to the sum of signals to the summing logic circuit. A servo system that is operably connected to receive said third output signal and compare it with a reference voltage to develop a slowly varying feedback voltage to control the variable-gain amplifier in said common amplifier-detector circuit in order to make said first and second output signals independent of variations in the magnitude of the sum of said input signals. 2 figures.

Bittner, J.W.; Biscardi, R.W.

1991-03-19

400

Apparatus and method for detecting and measuring changes in linear relationships between a number of high frequency signals  

DOEpatents

An electronic measurement circuit for high speed comparison of the relative amplitudes of a predetermined number of electrical input signals independent of variations in the magnitude of the sum of the signals. The circuit includes a high speed electronic switch that is operably connected to receive on its respective input terminals one of said electrical input signals and to have its common terminal serve as an input for a variable-gain amplifier-detector circuit that is operably connected to feed its output to a common terminal of a second high speed electronic switch. The respective terminals of the second high speed electronic switch are operably connected to a plurality of integrating sample and hold circuits, which in turn have their outputs connected to a summing logic circuit that is operable to develop first, second and third output voltages, the first output voltage being proportional to a predetermined ratio of sums and differences between the compared input signals, the second output voltage being proportional to a second summed ratio of predetermined sums and differences between said input signals, and the third output voltage being proportional to the sum of signals to the summing logic circuit. A servo system that is operably connected to receive said third output signal and compare it with a reference voltage to develop a slowly varying feedback voltage to control the variable-gain amplifier in said common amplifier-detector circuit in order to make said first and second output signals independent of variations in the magnitude of the sum of said input signals.

Bittner, John W. (Shoreham, NY); Biscardi, Richard W. (Ridge, NY)

1991-01-01

401

Modeling the eddy transport of momentum and heat: Comparison with direct measurements in free atmosphere  

NASA Astrophysics Data System (ADS)

Direct measurements of eddy diffusivities for momentum K m and heat K h by Doppler radar and by a radio acoustic sounding system in the upper troposphere and lower stratosphere were used to examine the applicability of three Reynolds-averaged Navier-Stokes (RANS) schemes of stratified turbulence in the environment: the E — ? turbulence scheme modified for stratified flows, the algebraic two-parameter E — ? Reynolds-stress scheme, and the three-parameter turbulence scheme. All turbulence parameters-the turbulent kinetic energy ( E), the dissipation rate (?), and vertical profiles of potential temperature (atmospheric stability) and mean wind velocity-were derived from direct measurements for all three turbulence schemes. It is shown that the profile of the vertical diffusivity of momentum ( K m ) obtained from the three-parameter RANS turbulence scheme agrees well with its directly measured analog. The profile of K m calculated by the two-parameter turbulence schemes fits measurements rather qualitatively.

Kurbatskii, A. F.; Kurbatskaya, L. I.

2014-07-01

402

Flight Measurements of Average Skin-Friction Coefficients on a Parabolic Body of Revolution (NACA RM-10) at Mach Numbers from 1.0 to 3.7  

NASA Technical Reports Server (NTRS)

Measurement of average skin-friction coefficients have been made on six rocket-powered free-flight models by using the boundary-layer rake technique. The model configuration was the NACA RM-10, a 12.2-fineness-ratio parabolic body of revolution with a flat base. Measurements were made over a Mach number range from 1 to 3.7, a Reynolds number range 40 x 10(exp 6) to 170 x 10(exp 6) based on length to the measurement station, and with aerodynamic heating conditions varying from strong skin heating to strong skin cooling. The measurements show the same trends over the test ranges as Van Driest's theory for turbulent boundary layer on a flat plate. The measured values are approximately 7 percent higher than the values of the flat-plate theory. A comparison which takes into account the differences in Reynolds number is made between the present results and skin-friction measurements obtained on NACA RM-10 scale models in the Langley 4- by 4-foot supersonic pressure tunnel, the Lewis 8- by 6-foot supersonic tunnel, and the Langley 9-inch supersonic tunnel. Good agreement is shown at all but the lowest tunnel Reynolds number conditions. A simple empirical equation is developed which represents the measurements over the range of the tests.

Loposer, J. Dan; Rumsey, Charles B.

1954-01-01

403

Measurement of electron transport properties of molecular junctions fabricated by electrochemical and mechanical methods  

NASA Astrophysics Data System (ADS)

We describe two methods to fabricate metal-molecule-metal junctions. The first method starts with a pair of electrodes separated with a molecular scale gap on an oxidized silicon substrate. These electrodes are fabricated by combining electron beam lithography and electrochemical deposition/etching. A molecular junction is formed when a molecule bridges the gap. This method can fabricate rather stable molecular junctions, however, the yield is low and the exact number of molecules in the junctions is uncertain. The second method forms a molecular junction by separating a scanning tunneling microscope tip from contact with a metal substrate in a solution containing sample molecules. This method, although is not device compatible, can create a large number of molecular junctions over a short period of time, which is ideal for statistical analysis.

Li, X. L.; He, H. X.; Xu, B. Q.; Xiao, X. Y.; Nagahara, L. A.; Amlani, I.; Tsui, R.; Tao, N. J.

2004-12-01

404

Histological Estimates of Ovariole Number in Honey Bee Queens, Apis mellifera, Reveal Lack of Correlation with other Queen Quality Measures  

PubMed Central

Published estimates of the number of ovarioles found in the ovaries of honey bee, Apis mellifera L. (Hymenoptera: Apidae) queens range from 100 to 180 per ovary. Within the context of a large-scale study designed to assay the overall quality of queens obtained from various commercial sources, a simple histology-based method for accurate determination of ovariole number was developed and then applied to a sample of 75 queens. Although all 10 commercial sources evaluated provided queens with ovariole numbers within the expected range, ovariole number was found to vary significantly across sources. Overall, and within most of the individual samples, there was no correlation of ovariole number with other morphological attributes such as thoracic width, wing length, or wet weight. Queens from two of the sources, however, displayed a significant negative relationship between wet weight and ovariole number. This study provides baseline data on ovariole number in commercial honey bee queens in the United States at a time when honey bee populations are declining; the method described can be used in studies relating ovariole number in queens to egg production and behavior. PMID:21870968

Jackson, Jeffrey T.; Tarpy, David R.; Fahrbach, Susan E.

2011-01-01

405

Commercial apparatus for measuring thermal transport properties from 1.9 to 390 kelvin  

NASA Astrophysics Data System (ADS)

We have developed an instrument which simultaneously measures the thermal conductivity ?, Seebeck coefficient ?, and electrical resistivity ? of a sample, thereby determining the thermoelectric figure of merit Z = ? ^2 / ? ?. A Quantum Design Physical Property Measurement System (PPMS) provides the temperature control from 1.9 - 390 K and applied magnetic fields of up to 14 tesla. Two small probes mounted along the sample each contain thin film Cernox chip thermometers as well as electrical contacts to monitor the temperature and voltage drops across the sample. A third probe attached to the end of the sample provides a heater and current source to stimulate the sample both thermally and electrically. The sample's response to cyclic heat pulses is analyzed in real time using DSP techniques. A nonlinear least-squares fit is used, employing a two time-constant model to determine both the thermal conductivity and the Seebeck coefficient for the material. Data acquisition using these ac techniques are expedited since we can sweep both temperature and field during a measurement. Adaptive algorithms continually adjust the thermal and electrical stimuli applied to the sample, optimizing the speed and accuracy of the measurement. We present results from some of the materials measured so far, including Pb in the superconducting state.

Dilley, N. R.; Black, R. C.; Montes, L.; Wilson, A.; Simmonds, M. B.

2001-03-01

406

Numerical modeling and experimental measurements of water spray impact and transport over a cylinder.  

SciTech Connect

This study compares experimental measurements and numerical simulations of liquid droplets over heated (to a near surface temperature of 423 K) and unheated cylinders. The numerical model is based on an unsteady Reynolds-averaged Navier-Stokes (RANS) formulation using a stochastic separated flow (SSF) approach for the droplets that includes submodels for droplet dispersion, heat and mass transfer, and impact on a solid surface. The details of the droplet impact model are presented and the model is used to simulate water spray impingement on a cylinder. Computational results are compared with experimental measurements using phase Doppler interferometry (PDI).

Avedisian, C. T. (Cornell University, Ithaca, NY); Presser, Cary (National Institute of Standard & Technology, Gaithersburg, MD); DesJardin, Paul Edward (University at Buffalo, New York, NY); Hewson, John C.; Yoon, Sam Sukgoo

2005-03-01

407

The measurement of water transport in porous materials using impedance spectroscopy  

NASA Astrophysics Data System (ADS)

This paper describes the application of electrical measurements to monitor the extraction (movement of water from the mortar) of water from calcium lime, natural hydraulic lime and Portland cement mortars placed on an adsorbent brick substrate. Impedance measurements were used to identify the changes in bulk resistance of the mortar. A model has been developed combining sharp front theory and Boltzmann's distribution law of statistical thermodynamics to identify the point at which no further absorption of water into the brick occurs. A linear relationship was found between the exponential of bulk resistance and the square root of time during dewatering. A change in gradient was attributed to the end of dewatering.

Ball, R. J.; Allen, G. C.

2010-03-01

408

J/{Psi} production in nuclear collisions: Theoretical approach to measuring the transport coefficient  

SciTech Connect

The observed p{sub T} dependence of nuclear effects for J/{Psi} produced in heavy-ion collisions at Brookhaven's Relativistic Heavy-Ion Collider (RHIC) might look puzzling, because the nuclear suppression seems to fade at large p{sub T}. We explain this by the interplay of three mechanisms: (i) attenuation of J/{Psi} in the hot medium created in the nuclear collision; (ii) initial-state shadowing of charmed quarks and attenuation of a c-barc dipole propagating through the colliding nuclei; (iii) a strong Cronin effect for J/{Psi} caused by saturation of gluons in the colliding nuclei. All three effects are well under control and calculated in a parameter-free way, except for the transport coefficient q{sub 0} characterizing the medium. This is adjusted to the J/{Psi} data and found to be in good agreement with the pQCD prediction, but more than an order of magnitude smaller than what was extracted from jet quenching data within the energy loss scenario.

Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan [Departamento de Fisica, Instituto de Avanzados en Ciencias en Ingeneria, Universidad Tecnica Federico Santa Maria, Centro Cientifico-Tecnologico de Valparaiso, Casilla 110-V, Valparaiso (Chile)

2010-08-15

409

Measuring mRNA copy-number in individual Escherichia coli cells using single-molecule fluorescent in situ hybridization (smFISH)  

PubMed Central

We present a method for measuring the absolute number of mRNA molecules from a gene of interest in individual, chemically fixed Escherichia coli cells. A set of fluorescently-labeled oligonucleotide probes are hybridized to the target mRNA, so that each mRNA molecule is decorated by a known number of fluorescent dyes. Cells are then imaged using fluorescence microscopy. The