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1

Unraveling the Electronic Structure of Azolehemiporphyrazines: Direct Spectroscopic Observation of Magnetic Dipole Allowed Nature of the Lowest ?-?* Transition of 20?-Electron Porphyrinoids.  

PubMed

Hemiporphyrazines are a large family of phthalocyanine analogues in which two isoindoline units are replaced by other rings. Here we report unambiguous identification of 20?-electron structure of triazolehemiporphyrazines (1, 2) and thiazolehemiporphyrazine (3) by means of X-ray analysis, various spectroscopic methods, and density functional theory (DFT) calculations. The hemiporphyrazines were compared in detail with dibenzotetraazaporphyrin (4), a structurally related 18?-electron molecule. X-ray analysis revealed that tetrakis(2,6-dimethylphenyloxy)triazolehemiporphyrazine (1b) adopted planar geometry in the solid state. A weak absorption band with a pronounced vibronic progression, observed for all the hemiporphyrazines, was attributed to the lowest ?-?* transition with the electric-dipole-forbidden nature. In the case of intrinsically chiral vanadyl triazolehemiporphyrazine (2), a large dissymmetry (g) factor was detected for the CD signal corresponding to the lowest ?-?* transition with the magnetic-dipole-allowed nature. Molecular orbital analysis and NICS calculations showed that the azolehemiporphyrazines have a 20?-electron system with a weak paratropic ring current. PMID:24866729

Muranaka, Atsuya; Ohira, Shino; Toriumi, Naoyuki; Hirayama, Machiko; Kyotani, Fumiko; Mori, Yukie; Hashizume, Daisuke; Uchiyama, Masanobu

2014-06-26

2

Periodic reversal of direction allows Myxobacteria to swarm  

PubMed Central

Many bacteria can rapidly traverse surfaces from which they are extracting nutrient for growth. They generate flat, spreading colonies, called swarms because they resemble swarms of insects. We seek to understand how members of any dense swarm spread efficiently while being able to perceive and interfere minimally with the motion of others. To this end, we investigate swarms of the myxobacterium, Myxococcus xanthus. Individual M. xanthus cells are elongated; they always move in the direction of their long axis; and they are in constant motion, repeatedly touching each other. Remarkably, they regularly reverse their gliding directions. We have constructed a detailed cell- and behavior-based computational model of M. xanthus swarming that allows the organization of cells to be computed. By using the model, we are able to show that reversals of gliding direction are essential for swarming and that reversals increase the outflow of cells across the edge of the swarm. Cells at the swarm edge gain maximum exposure to nutrient and oxygen. We also find that the reversal period predicted to maximize the outflow of cells is the same (within the errors of measurement) as the period observed in experiments with normal M. xanthus cells. This coincidence suggests that the circuit regulating reversals evolved to its current sensitivity under selection for growth achieved by swarming. Finally, we observe that, with time, reversals increase the cell alignment, and generate clusters of parallel cells.

Wu, Yilin; Kaiser, A. Dale; Jiang, Yi; Alber, Mark S.

2009-01-01

3

Direct observation detonator operation  

NASA Astrophysics Data System (ADS)

The analysis of detonator-timing performance has involved the use of rotating-mirror cameras (RMC) used in the streak mode and high-speed film. Fiducial timing marks are applied to the film to provide temporal references. The use of a RMC for detonator analysis requires aligning the camera, performing an exposure test, capturing light from the detonation and then processing the film. This procedure can take up to an hour for two technicians. After the film is possessed another technician compares each light streak on the film with the fiducial timing marks also recorded on the film. Capturing light from a detonator and recording it directly to a digitizer can improve detonator-timing measurement in several ways. The digitized signals can then be directly analyzed with software. The direct recording method reduces the need for expensive rotating mirror cameras, film processing and subjective optical measurement comparison. Furthermore, an extensive support facility requiring several specialized technicians is reduced to a single technician in a modest laboratory. This technician is then capable of performing several tests an hour. Tests were preformed to measure light intensity at detonation. An optical method of capturing the light was designed using a remote microscope coupled to optical fiber to bring the light to an optical/electrical converter and a digitizer then records the signal. This system is presently used in parallel with a RMC. The results are compared for accuracy.

Hall, Charles R.

2001-11-01

4

Does general relativity allow an observer to view an eternity in a finite time?  

Microsoft Academic Search

I investigate whether there are general relativistic spacetimes that allow an observerµ to collect in a finite time all the data from the worldline of another observer?, where the proper length of?'s worldline is infinite. The existence of these spacetimes has a bearing on certain problems in computation theory. A theorem shows that most standard spacetimes cannot accommodate this scenario.

Mark L. Hogarth

1992-01-01

5

Switchable reporter enzymes based on mutually exclusive domain interactions allow antibody detection directly in solution  

PubMed Central

Detection of antibodies is essential for the diagnosis of many diseases including infections, allergies and autoimmune diseases. Current heterogeneous immunoassays require multiple time-consuming binding and washing steps, which limits their application in point-of-care diagnostics and high-throughput screening. Here we report switchable reporter enzymes that allow simple colorimetric detection of antibodies directly in solution. Our approach is based on the antibody-induced disruption of an intramolecular interaction between TEM1-?-lactamase and its inhibitor protein BLIP. Using the HIV1-p17 antibody as an initial target, the interaction between enzyme and inhibitor was carefully tuned to yield a reporter enzyme whose activity increased 10-fold in the presence of pM antibody concentrations. Reporter enzymes for two other antibodies (HA-tag and Dengue virus type I) were obtained by simply replacing the epitope sequences. This new sensor design represents a modular and generic approach to construct antibody reporter enzymes without the cumbersome optimization required by previous engineering strategies.

Banala, Sambashiva; Aper, Stijn J.A.; Schalk, Werner; Merkx, Maarten

2013-01-01

6

Switchable reporter enzymes based on mutually exclusive domain interactions allow antibody detection directly in solution.  

PubMed

Detection of antibodies is essential for the diagnosis of many diseases including infections, allergies, and autoimmune diseases. Current heterogeneous immunoassays require multiple time-consuming binding and washing steps, which limits their application in point-of-care diagnostics and high-throughput screening. Here, we report switchable reporter enzymes that allow simple colorimetric detection of antibodies directly in solution. Our approach is based on the antibody-induced disruption of an intramolecular interaction between TEM1 ?-lactamase and its inhibitor protein BLIP. Using the HIV1-p17 antibody as an initial target, the interaction between enzyme and inhibitor was carefully tuned to yield a reporter enzyme whose activity increased 10-fold in the presence of pM antibody concentrations. Reporter enzymes for two other antibodies (HA-tag and Dengue virus type I) were obtained by simply replacing the epitope sequences. This new sensor design represents a modular and generic approach to construct antibody reporter enzymes without the cumbersome optimization required by previous engineering strategies. PMID:23941162

Banala, Sambashiva; Aper, Stijn J A; Schalk, Werner; Merkx, Maarten

2013-10-18

7

Toward a Direct Realist Account of Observation.  

ERIC Educational Resources Information Center

Criticizes the account of observation given by Alan Chalmers in "What Is This Thing Called Science?" and provides an alternative based on direct realist approaches to perception. Contains 15 references. (Author/WRM)

Sievers, K. H.

1999-01-01

8

Observe how the monsoon changes direction  

NSDL National Science Digital Library

This Earth science animation shows high school students how changes in wind speed and direction are associated with the Asian monsoon. The introduction explains how seasonal movement of air pressure belts cause winds to change direction. The animation uses a map to present the average April to December precipitation in Asia during the years 1985-1989. Color-enhancement indicates precipitation, and wind speed and direction are designated by arrows. Movie controls allow students to repeat, pause, or step through the animation, which can give students more time to analyze the images. Copyright 2005 Eisenhower National Clearinghouse

Education, Terc. C.; Littell, Mcdougal

2003-01-01

9

Direct observation of the direction of motion for spherical catalytic swimmers.  

PubMed

Nonconductive Janus particle swimmers made by coating fluorescent polymer beads with hemispheres of platinum have been fully characterized using video microscopy to reveal that they undergo propulsion in hydrogen peroxide fuel away from the catalytic platinum patch. The platinum coating shadows the fluorescence signal from half of each swimmer to allow the orientation to be observed directly and correlated quantitatively with the resulting swimming direction. The observed swimmer direction is consistent with both the bubble release and diffusiophoretic propulsion mechanisms. PMID:21928845

Ebbens, Stephen J; Howse, Jonathan R

2011-10-18

10

Characterizing direction of coupling from experimental observations.  

PubMed

We demonstrate that the direction of coupling of two interacting self-sustained electronic oscillators can be determined from the realizations of their signals. In our experiments, two electronic generators, operating in a periodic or a chaotic state, were subject to symmetrical or unidirectional coupling. In data processing, first the phases have been extracted from the observed signals and then the directionality of coupling was quantitatively estimated from the analysis of mutual dependence of the phase dynamics. PMID:12675424

Bezruchko, Boris; Ponomarenko, Vladimir; Rosenblum, Michael G; Pikovsky, Arkady S

2003-03-01

11

Observations on human tactile directional sensibility.  

PubMed

1. The ability to tell the direction of a motion across the skin deserve attention for being an easily observed function which provides a sensitive test for disturbances of the peripheral and central nervous systems. The mode of operation, on the other hand, of this tactile directional sensibility is still uncertain. 2. The dependence of directional sensibility on the contact load and distance of movement of a blunt metal tip, has now been determined for the skin of the forearm of normal subjects with the two-alternative forced-choice method. The testing was done under two conditions: elbow bent or straight. Straightening of the arm always reduced the accuracy of the directional sensibility. It also caused measurable changes of cutaneous mechanical properties, which presumably decreased the reliability of afferent information about lateral distension. 3. The average accuracy of the directional sensibility was found to be correlated linearly to the logarithm of the contact load, and straightening of the arm decreased the accuracy for each load by corresponding amounts. Similar relationships were found between the accuracy and the distance of movement. 4. Straightening of the arm did not cause any significant average reduction of the contact threshold for point stimulation of the same receptive field. A consistently lowered contact sensitivity, however, was observed for some of the subjects, which may have contributed to the reduction of the directional sensibility in these cases. 5. Correct directional estimations of the movement of the metal tip were obtained for a distance which was a fifth of the shortest distance for a corresponding estimation of the movement of a frictionless stimulus. The findings thus indicated that the friction between a moving object and the underlying skin, which can be mediated via stretch-sensitive cutaneous receptors, is critical for the determination of its direction of motion. 6. The present observations and previous observations by various authors are suggested to indicate that typical tactile directional sensibility depends on parallel processing of direction-selective data, and spatial data expressed as a function of time. PMID:8229817

Olausson, H; Norrsell, U

1993-05-01

12

Observations on human tactile directional sensibility.  

PubMed Central

1. The ability to tell the direction of a motion across the skin deserve attention for being an easily observed function which provides a sensitive test for disturbances of the peripheral and central nervous systems. The mode of operation, on the other hand, of this tactile directional sensibility is still uncertain. 2. The dependence of directional sensibility on the contact load and distance of movement of a blunt metal tip, has now been determined for the skin of the forearm of normal subjects with the two-alternative forced-choice method. The testing was done under two conditions: elbow bent or straight. Straightening of the arm always reduced the accuracy of the directional sensibility. It also caused measurable changes of cutaneous mechanical properties, which presumably decreased the reliability of afferent information about lateral distension. 3. The average accuracy of the directional sensibility was found to be correlated linearly to the logarithm of the contact load, and straightening of the arm decreased the accuracy for each load by corresponding amounts. Similar relationships were found between the accuracy and the distance of movement. 4. Straightening of the arm did not cause any significant average reduction of the contact threshold for point stimulation of the same receptive field. A consistently lowered contact sensitivity, however, was observed for some of the subjects, which may have contributed to the reduction of the directional sensibility in these cases. 5. Correct directional estimations of the movement of the metal tip were obtained for a distance which was a fifth of the shortest distance for a corresponding estimation of the movement of a frictionless stimulus. The findings thus indicated that the friction between a moving object and the underlying skin, which can be mediated via stretch-sensitive cutaneous receptors, is critical for the determination of its direction of motion. 6. The present observations and previous observations by various authors are suggested to indicate that typical tactile directional sensibility depends on parallel processing of direction-selective data, and spatial data expressed as a function of time. Images Fig. 1

Olausson, H; Norrsell, U

1993-01-01

13

Catalytic carbene transfer allows the direct customization of cyclic purine dinucleotides.  

PubMed

We describe a simple method for the direct modification of nucleobases in cyclic purine dinucleotides, important signalling molecules in both prokaryotes and eukaryotes. The method tolerates all members of the cyclic dinucleotide family and could be used to modulate their function or introduce useful side-chains such as fluorophores and photo-crosslinking groups. PMID:24946836

Fei, Na; Häussinger, Daniel; Blümli, Seraina; Laventie, Benoît-Joseph; Bizzini, Lorenzo D; Zimmermann, Kaspar; Jenal, Urs; Gillingham, Dennis

2014-07-01

14

Direct observation of beamed Raman scattering.  

PubMed

Appropriately designed surface plasmon nanostructures enable the emission patterns of surface-enhanced Raman scattering to be modified to facilitate efficient collection, an effect sometimes termed "beamed Raman scattering". Here, we demonstrate the direct and unambiguous observation of this phenomenon by separating the Raman emission pattern from the luminescent background using energy momentum spectroscopy. We observe beamed Raman scattering from two types of optical antennas: the first are Yagi-Uda optical antennas, and the second are optical dimer antennas formed above a plasmonic substrate consisting of a gold film integrated with a one-dimensional array of gold stripes. For both antenna types, the emission patterns from different Raman lines are simultaneously measured. For the second antenna type, the emission patterns show signatures stemming from the bandstructure of the plasmonic substrate. PMID:23101429

Zhu, Wenqi; Wang, Dongxing; Crozier, Kenneth B

2012-12-12

15

First direct observation of muon antineutrino disappearance.  

PubMed

This Letter reports the first direct observation of muon antineutrino disappearance. The MINOS experiment has taken data with an accelerator beam optimized for ?(?) production, accumulating an exposure of 1.71 × 10²? protons on target. In the Far Detector, 97 charged current ?(?) events are observed. The no-oscillation hypothesis predicts 156 events and is excluded at 6.3?. The best fit to oscillation yields |?m²| = [3.36(-0.40)(+0.46)(stat) ± 0.06(syst)] × 10?³ eV², sin²(2?) = 0.86(-0.12)(+0.11)(stat) ± 0.01(syst). The MINOS ?(?) and ?(?) measurements are consistent at the 2.0% confidence level, assuming identical underlying oscillation parameters. PMID:21797594

Adamson, P; Andreopoulos, C; Auty, D J; Ayres, D S; Backhouse, C; Barr, G; Bishai, M; Blake, A; Bock, G J; Boehnlein, D J; Bogert, D; Cavanaugh, S; Cherdack, D; Childress, S; Choudhary, B C; Coelho, J A B; Coleman, S J; Corwin, L; Cronin-Hennessy, D; Danko, I Z; de Jong, J K; Devenish, N E; Diwan, M V; Dorman, M; Escobar, C O; Evans, J J; Falk, E; Feldman, G J; Frohne, M V; Gallagher, H R; Gomes, R A; Goodman, M C; Gouffon, P; Graf, N; Gran, R; Grant, N; Grzelak, K; Habig, A; Harris, D; Hartnell, J; Hatcher, R; Himmel, A; Holin, A; Howcroft, C; Huang, X; Hylen, J; Ilic, J; Irwin, G M; Isvan, Z; Jaffe, D E; James, C; Jensen, D; Kafka, T; Kasahara, S M S; Koizumi, G; Kopp, S; Kordosky, M; Kreymer, A; Lang, K; Lefeuvre, G; Ling, J; Litchfield, P J; Loiacono, L; Lucas, P; Mann, W A; Marshak, M L; Mayer, N; McGowan, A M; Mehdiyev, R; Meier, J R; Messier, M D; Miller, W H; Mishra, S R; Mitchell, J; Moore, C D; Morfín, J; Mualem, L; Mufson, S; Musser, J; Naples, D; Nelson, J K; Newman, H B; Nichol, R J; Nicholls, T C; Nowak, J A; Ochoa-Ricoux, J P; Oliver, W P; Orchanian, M; Ospanov, R; Paley, J; Patterson, R B; Pawloski, G; Pearce, G F; Petyt, D A; Phan-Budd, S; Plunkett, R K; Qiu, X; Ratchford, J; Raufer, T M; Rebel, B; Rodrigues, P A; Rosenfeld, C; Rubin, H A; Sanchez, M C; Schneps, J; Schreiner, P; Shanahan, P; Sousa, A; Stamoulis, P; Strait, M; Tagg, N; Talaga, R L; Tetteh-Lartey, E; Thomas, J; Thomson, M A; Tinti, G; Toner, R; Tzanakos, G; Urheim, J; Vahle, P; Viren, B; Weber, A; Webb, R C; White, C; Whitehead, L; Wojcicki, S G; Yang, T; Zwaska, R

2011-07-01

16

Direct observation of type 1 fimbrial switching  

PubMed Central

The defining feature of bacterial phase variation is a stochastic ‘all-or-nothing' switching in gene expression. However, direct observations of these rare switching events have so far been lacking, obscuring possible correlations between switching events themselves, and between switching and other cellular events, such as division and DNA replication. We monitored the phase variation of type 1 fimbriae in individual Escherichia coli in real time and simultaneously tracked the chromosome replication process. We observed distinctive patterns of fim (fimbriae) expression in multiple genealogically related lineages. These patterns could be explained by a model that combines a single switching event with chromosomal fim replication, as well as the epigenetic inheritance of expressed fim protein and RNA, and their dilution by growth. Analysis of the moment of switching at sub-cell-cycle resolution revealed a correlation between fim switching and cell age, which challenges the traditional idea of phase variation as a random Poissonian phenomenon.

Adiciptaningrum, Aileen M; Blomfield, Ian C; Tans, Sander J

2009-01-01

17

Direct observation of sub-binomial light.  

PubMed

Nonclassical states of light are necessary resources for quantum technologies such as cryptography, computation and the definition of metrological standards. Observing signatures of nonclassicality generally requires inferring either the photon number distribution or a quasiprobability distribution indirectly from a set of measurements. Here, we report an experiment in which the nonclassical character of families of quantum states is assessed by direct inspection of the outcomes from a multiplexed photon counter. This scheme does not register the actual photon number distribution; the statistics of the detector clicks alone serve as a witness of nonclassicality, as proposed by Sperling et al. [Phys. Rev. Lett. 109, 093601 (2012)]. Our work paves a way for the practical characterization of increasingly sophisticated states and detectors. PMID:23679726

Bartley, Tim J; Donati, Gaia; Jin, Xian-Min; Datta, Animesh; Barbieri, Marco; Walmsley, Ian A

2013-04-26

18

Direct observation of laser induced freezing  

NASA Astrophysics Data System (ADS)

The effect of an externally applied field on the microstructure of aqueous suspensions of charge stabilized polystyrene spheres is studied by direct observation. This work complements the earlier light diffraction work of Chowdhury et al., which demonstrated that radiation pressure forces can induce crystal-like microstructures in suspensions which have equilibrium liquid-like microstructures in the absence of these external fields. Specifically, a spatially periodic radiation pressure field is produced by intersecting two mutually coherent laser beams in the sample. The microstructure is observed as a function of the input intensity and crossing angle of the two laser beams, and the data is presented in terms of one and two dimensional particle distribution functions. We find that both single- and multilayered systems exhibit a transition to crystal-like order. This crystal order is more pronounced at large input power and for a periodic external field commensurate with the lattice spacing for a final undistorted two dimensional hexagonal crystal structure. Monolayer suspensions undergo this recording with no change in density, while multilayer systems restructure to a monolayer with increased layer density.

Loudiyi, K.; Ackerson, Bruce J.

1992-06-01

19

Direct observation of amyloid nucleation under nanomechanical stretching  

NASA Astrophysics Data System (ADS)

Self-assembly of amyloid nanofiber is associated with functional and pathological processes such as in neurodegenerative diseases. Despite intensive studies, stochastic nature of the process has made it difficult to elucidate molecular mechanisms for the key amyloid nucleation. Here, we investigated the amyloid nucleation of silk-elastin-like peptide (SELP) using time-lapse lateral force microscopy (LFM). By repeated scanning a single line on a SELP-coated mica surface, we observed sudden stepwise height increases, corresponds to nucleation of an amyloid fiber. The lateral force profiles followed either a worm-like chain model or an exponential function, suggesting that the atomic force microscopy (AFM) tip stretches a single or multiple SELP molecules along the scanning direction, serves as the template for further self-assembly perpendicular to the scan direction. Such mechanically induced nucleation of amyloid fibrils allows positional and directional control of amyloid assembly in vitro , which we demonstrate by generating single nanofibers at predetermined nucleation sites.

Varongchayakul, Nitinun

20

Emerging feed-forward inhibition allows the robust formation of direction selectivity in the developing ferret visual cortex.  

PubMed

The computation of direction selectivity requires that a cell respond to joint spatial and temporal characteristics of the stimulus that cannot be separated into independent components. Direction selectivity in ferret visual cortex is not present at the time of eye opening but instead develops in the days and weeks following eye opening in a process that requires visual experience with moving stimuli. Classic Hebbian or spike timing-dependent modification of excitatory feed-forward synaptic inputs is unable to produce direction-selective cells from unselective or weakly directionally biased initial conditions because inputs eventually grow so strong that they can independently drive cortical neurons, violating the joint spatial-temporal activation requirement. Furthermore, without some form of synaptic competition, cells cannot develop direction selectivity in response to training with bidirectional stimulation, as cells in ferret visual cortex do. We show that imposing a maximum lateral geniculate nucleus (LGN)-to-cortex synaptic weight allows neurons to develop direction-selective responses that maintain the requirement for joint spatial and temporal activation. We demonstrate that a novel form of inhibitory plasticity, postsynaptic activity-dependent long-term potentiation of inhibition (POSD-LTPi), which operates in the developing cortex at the time of eye opening, can provide synaptic competition and enables robust development of direction-selective receptive fields with unidirectional or bidirectional stimulation. We propose a general model of the development of spatiotemporal receptive fields that consists of two phases: an experience-independent establishment of initial biases, followed by an experience-dependent amplification or modification of these biases via correlation-based plasticity of excitatory inputs that compete against gradually increasing feed-forward inhibition. PMID:24598528

Van Hooser, Stephen D; Escobar, Gina M; Maffei, Arianna; Miller, Paul

2014-06-01

21

[Calculation of allowable pollution loads for lake and reservoir based on bi-direction algorithm and its case study].  

PubMed

Based on the reviews and summaries of water environment carrying capacity researches and practices, the main problems of allowable pollutants load estimation and its allocation in China were analyzed. Then a bi-direction algorithm for allowable pollutants loads calculation was proposed to support the pollutants loads management in the lake and reservoir control units. It was the combination of forward algorithm and backward algorithm. The two major steps were modeling and scenario analysis. Firstly, the basic scenario was proposed using the estimation model. Then the basic scenario was analyzed using the water quality simulation model to assess the compliance of water quality objectives. The allowable pollutant loads were calculated after several loops of scenario simulation, result analysis and scenario optimization. Finally, the Chaihe Reservoir in Liaoning Province, China was used as a case study using Environmental Fluid Dynamic Code (EFDC) model as the kernel model. The results demonstrated that the algorithm proposed provided an efficient and appropriate methodology for allowable pollutant load calculation. PMID:24812947

Jia, Hai-Feng; Guo, Yu

2014-02-01

22

Wind direction modelling using multiple observation points.  

PubMed

The prediction of wind direction is a prerequisite for the intelligent and efficient operation of wind turbines. This is a complex task, due to the intermittent behaviour of wind, its non-Gaussian and nonlinear nature, and the coupling between the wind speed and direction. To provide improved wind direction forecasting, we propose a nonlinear model with augmented information from an additional measurement point. This is further enhanced by making use of both the speed and direction components of the wind field vector. The analysis and a comprehensive set of simulations demonstrate that the proposed approach achieves improved prediction performance over the standard and persistent model. The potential of the proposed approach is justified by the fact that even relatively small improvements in the forecasts result in large gains in the produced output power. PMID:17698475

Hirata, Yoshito; Mandic, Danilo P; Suzuki, Hideyuki; Aihara, Kazuyuki

2008-02-28

23

How to observe coherent electron dynamics directly.  

PubMed

Detection of electron motion by elastic scattering of short x-ray pulses from a coherent superposition of highly excited electronic states in rare gas atoms is investigated. The laser excitation of the electron wave packet introduces strong anisotropy which facilitates detection, and large differences in the radial distribution of the excited Rydberg and core electrons allow the dynamics to be detected using both soft and hard x rays. PMID:24580446

Suominen, Henri J; Kirrander, Adam

2014-01-31

24

Observation of direct-CP violation.  

National Technical Information Service (NTIS)

Using a subset of data collected in the 1996-97 fixed target run at Fermilab, the authors report the first preliminary measurement on the direct-CP violation from the KTeV experiment. The result is, e(prime)/e = (28.0-4.1) x 10(sup (minus)4), nearly 7 sta...

Y. B. Hsiung

1999-01-01

25

Direct observation of longitudinally polarised W ± bosons  

Microsoft Academic Search

The three different helicity states of W± bosons, produced in the reaction e+e??W+W????qq? are studied using leptonic and hadronic W decays at s=183 GeV and 189 GeV. The W polarisation is also measured as a function of the scattering angle between the W? and the direction of the e? beam. The analysis demonstrates that W bosons are produced with all

M. Acciarri; P. Achard; O. Adriani; M. Aguilar-Benitez; J. Alcaraz; G. Alemanni; J. Allaby; A. Aloisio; M. G. Alviggi; G. Ambrosi; H. Anderhub; V. P. Andreev; T. Angelescu; F. Anselmo; A. Arefiev; T. Azemoon; T. Aziz; P. Bagnaia; L. Baksay; A. Balandras; R. C. Ball; S. Banerjee; A. Barczyk; R. Barillère; L. Barone; P. Bartalini; M. Basile; R. Battiston; A. Bay; F. Becattini; U. Becker; F. Behner; L. Bellucci; J. Berdugo; P. Berges; B. Bertucci; B. L. Betev; S. Bhattacharya; M. Biasini; A. Biland; J. J. Blaising; S. C. Blyth; G. J. Bobbink; A. Böhm; L. Boldizsar; B. Borgia; D. Bourilkov; M. Bourquin; S. Braccini; J. G. Branson; V. Brigljevic; F. Brochu; A. Buffini; A. Buijs; J. D. Burger; W. J. Burger; A. Button; X. D. Cai; M. Campanelli; M. Capell; G. Cara Romeo; G. Carlino; A. M. Cartacci; J. Casaus; G. Castellini; F. Cavallari; N. Cavallo; C. Cecchi; M. Cerrada; F. Cesaroni; M. Chamizo; Y. H. Chang; U. K. Chaturvedi; M. Chemarin; A. Chen; G. Chen; H. F. Chen; H. S. Chen; G. Chiefari; L. Cifarelli; F. Cindolo; C. Civinini; I. Clare; R. Clare; G. Coignet; A. P. Colijn; N. Colino; S. Costantini; F. Cotorobai; B. Cozzoni; B. de la Cruz; A. Csilling; S. Cucciarelli; T. S. Dai; J. A. van Dalen; R. D'Alessandro; R. de Asmundis; P. Déglon; A. Degré; K. Deiters; D. della Volpe; P. Denes; F. DeNotaristefani; A. De Salvo; M. Diemoz; D. van Dierendonck; F. Di Lodovico; C. Dionisi; M. Dittmar; A. Dominguez; A. Doria; M. T. Dova; D. Duchesneau; D. Dufournaud; P. Duinker; I. Duran; H. El Mamouni; A. Engler; F. J. Eppling; F. C. Erné; P. Extermann; M. Fabre; R. Faccini; M. A. Falagan; S. Falciano; A. Favara; J. Fay; O. Fedin; M. Felcini; T. Ferguson; F. Ferroni; H. Fesefeldt; E. Fiandrini; J. H. Field; F. Filthaut; P. H. Fisher; I. Fisk; G. Forconi; L. Fredj; K. Freudenreich; C. Furetta; Yu. Galaktionov; S. N. Ganguli; P. Garcia-Abia; M. Gataullin; S. S. Gau; S. Gentile; N. Gheordanescu; S. Giagu; Z. F. Gong; G. Grenier; O. Grimm; M. W. Gruenewald; M. Guida; R. van Gulik; V. K. Gupta; A. Gurtu; L. J. Gutay; D. Haas; A. Hasan; D. Hatzifotiadou; T. Hebbeker; A. Hervé; P. Hidas; J. Hirschfelder; H. Hofer; G. Holzner; H. Hoorani; S. R. Hou; I. Iashvili; B. N. Jin; L. W. Jones; P. de Jong; I. Josa-Mutuberr??a; R. A. Khan; M. Kaur; M. N. Kienzle-Focacci; D. Kim; J. K. Kim; S. C. Kim; J. Kirkby; D. Kiss; W. Kittel; A. Klimentov; A. C. König; A. Kopp; V. Koutsenko; M. Kräber; R. W. Kraemer; W. Krenz; A. Krüger; A. Kunin; P. Ladron de Guevara; I. Laktineh; G. Landi; K. Lassila-Perini; M. Lebeau; A. Lebedev; P. Lebrun; P. Lecomte; P. Lecoq; P. Le Coultre; H. J. Lee; J. M. Le Goff; R. Leiste; E. Leonardi; P. Levtchenko; C. Li; S. Likhoded; C. H. Lin; W. T. Lin; F. L. Linde; L. Lista; Z. A. Liu; W. Lohmann; E. Longo; Y. S. Lu; K. Lübelsmeyer; C. Luci; D. Luckey; L. Lugnier; L. Luminari; W. Lustermann; W. G. Ma; M. Maity; L. Malgeri; A. Malinin; C. Maña; D. Mangeol; P. Marchesini; G. Marian; J. P. Martin; F. Marzano; G. G. G. Massaro; K. Mazumdar; R. R. McNeil; S. Mele; L. Merola; M. Meschini; W. J. Metzger; M. von der Mey; A. Mihul; H. Milcent; G. Mirabelli; J. Mnich; G. B. Mohanty; P. Molnar; B. Monteleoni; T. Moulik; G. S. Muanza; F. Muheim; A. J. M. Muijs; M. Musy; M. Napolitano; F. Nessi-Tedaldi; H. Newman; T. Niessen; A. Nisati; H. Nowak; Y. D. Oh; G. Organtini; A. Oulianov; C. Palomares; D. Pandoulas; S. Paoletti; P. Paolucci; R. Paramatti; H. K. Park; I. H. Park; G. Pascale; G. Passaleva; S. Patricelli; T. Paul; M. Pauluzzi; C. Paus; F. Pauss; M. Pedace; S. Pensotti; D. Perret-Gallix; B. Petersen; D. Piccolo; F. Pierella; M. Pieri; P. A. Piroué; E. Pistolesi; V. Plyaskin; M. Pohl; V. Pojidaev; H. Postema; J. Pothier; N. Produit; D. Prokofiev; J. Quartieri; G. Rahal-Callot; M. A. Rahaman; P. Raics; N. Raja; R. Ramelli; P. G. Rancoita; A. Raspereza; G. Raven; P. Razis; D. Ren; M. Rescigno; S. Reucroft; T. van Rhee; S. Riemann; K. Riles; A. Robohm; J. Rodin; B. P. Roe; L. Romero; A. Rosca; S. Rosier-Lees; J. A. Rubio; D. Ruschmeier; H. Rykaczewski; S. Saremi; S. Sarkar; J. Salicio; E. Sanchez; M. P. Sanders; M. E. Sarakinos; C. Schäfer; V. Schegelsky; S. Schmidt-Kaerst; D. Schmitz; H. Schopper; D. J. Schotanus; G. Schwering; C. Sciacca; D. Sciarrino; A. Seganti; L. Servoli; S. Shevchenko; N. Shivarov; V. Shoutko; E. Shumilov; A. Shvorob; T. Siedenburg; D. Son; B. Smith; P. Spillantini; M. Steuer; D. P. Stickland; A. Stone; H. Stone; B. Stoyanov; A. Straessner; K. Sudhakar; G. Sultanov; L. Z. Sun; H. Suter; J. D. Swain; Z. Szillasi; T. Sztaricskai; X. W. Tang; L. Tauscher; L. Taylor; C. Timmermans; Samuel C. C. Ting; S. M. Ting; S. C. Tonwar; J. Tóth; C. Tully; K. L. Tung; Y. Uchida; J. Ulbricht; E. Valente; G. Vesztergombi; I. Vetlitsky; D. Vicinanza; G. Viertel; S. Villa; M. Vivargent; S. Vlachos; I. Vodopianov; H. Vogel; H. Vogt; I. Vorobiev; A. A. Vorobyov; A. Vorvolakos

2000-01-01

26

Type I interferons directly inhibit regulatory T cells to allow optimal antiviral T cell responses during acute LCMV infection.  

PubMed

Regulatory T (T reg) cells play an essential role in preventing autoimmunity but can also impair clearance of foreign pathogens. Paradoxically, signals known to promote T reg cell function are abundant during infection and could inappropriately enhance T reg cell activity. How T reg cell function is restrained during infection to allow the generation of effective antiviral responses remains largely unclear. We demonstrate that the potent antiviral type I interferons (IFNs) directly inhibit co-stimulation-dependent T reg cell activation and proliferation, both in vitro and in vivo during acute infection with lymphocytic choriomeningitis virus (LCMV). Loss of the type I IFN receptor specifically in T reg cells results in functional impairment of virus-specific CD8(+) and CD4(+) T cells and inefficient viral clearance. Together, these data demonstrate that inhibition of T reg cells by IFNs is necessary for the generation of optimal antiviral T cell responses during acute LCMV infection. PMID:24711580

Srivastava, Shivani; Koch, Meghan A; Pepper, Marion; Campbell, Daniel J

2014-05-01

27

Direct Observation of a Nonlocal Heat Wave  

NASA Astrophysics Data System (ADS)

We have measured spatially and temporally resolved electron density and electron temperature profiles in a laser produced nitrogen plasma utilizing Thomson laser scattering. Electron temperatures were obtained by imaging the ion-acoustic wave spectra across the entire spatial extent of the plasma. Rayleigh scattering was used to calibrate the instrument response in order to obtain absolute electron density measurements, and to image the probe and heater beam profiles at the laser focus. Our measurements, for the first time, show direct evidence of an expanding nonlocal heat wave. The experimental data agrees closely with nonlocal transport models, but disagrees significantly with fluid codes based on flux-limited models. This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48

Knight, Jason; Gregori, Gianluca; Glenzer, Siegfried; Niemann, Christoph; Price, Dwight; Froula, Dustin; Edwards, John; Town, Richard; Brantov, A.; Rozmus, Wojciech; Bychenkov, V. Yu.

2003-10-01

28

Direct Observation of Paramagnons in Palladium  

SciTech Connect

We report an inelastic neutron scattering study of the spin fluctuations in the nearly ferromagnetic element palladium. Dispersive over-damped collective magnetic excitations or 'paramagnons' are observed up to 128 meV. We analyze our results in terms of a Moriya-Lonzarich-type spin-fluctuation model and estimate the contribution of the spin fluctuations to the low-temperature heat capacity. In spite of the paramagnon excitations being relatively strong, their relaxation rates are large. This leads to a small contribution to the low-temperature electronic specific heat.

Doubble, R. [University of Bristol, UK; Hayden, S M. [University of Bristol, UK; Dai, Pengcheng [University of Tennessee, Knoxville (UTK); Mook Jr, Herbert A [ORNL; Thompson, James R [ORNL; Frost, C. [ISIS Facility, Rutherford Appleton Laboratory

2010-01-01

29

Time-gated luminescence microscopy allowing direct visual inspection of lanthanide-stained microorganisms in background-free condition.  

PubMed

Application of standard immuno-fluorescence microscopy techniques for detection of rare-event microorganisms in dirty samples is severely limited by autofluorescence of nontarget organisms or other debris. Time-gated detection using gateable array detectors in combination with microsecond-lifetime luminescent bioprobes (usually lanthanide-based) is highly effective in suppression of (nanosecond-lifetime) autofluorescence background; however, the complexity and cost of the instrumentation is a major barrier to application of these techniques to routine diagnostics. We report a practical, low-cost implementation of time-gated luminescence detection in a standard epifluorescence microscope which has been modified to include a high-power pulsed UV light-emitting diode (LED) illumination source and a standard fast chopper inserted in the focal plane behind a microscope eyepiece. Synchronization of the pulsed illumination/gated detection cycle is driven from the clock signal from the chopper. To achieve time-gated luminescence intensities sufficient for direct visual observation, we use high cycle rates, up to 2.5 kHz, taking advantage of the fast switching capabilities of the LED source. We have demonstrated real-time direct-visual inspection of europium-labeled Giardia lamblia cysts in dirty samples and Cryptosporidium parvum oocysts in fruit juice concentrate. The signal-to-background ratio has been enhanced by a factor of 18 in time-gated mode. The availability of low-cost, robust time-gated microscopes will aid development of long-lifetime luminescence bioprobes and accelerate their application in routine laboratory diagnostics. PMID:21344865

Jin, Dayong; Piper, James A

2011-03-15

30

Insertional mutagenesis of Listeria monocytogenes with a novel Tn917 derivative that allows direct cloning of DNA flanking transposon insertions.  

PubMed Central

To carry out efficient insertional mutagenesis in Listeria monocytogenes and to facilitate the characterization of disrupted genes, two novel derivatives of Tn917 were constructed, Tn917-LTV1 and Tn917-LTV3. The derivatives (i) transpose at a significantly elevated frequency, (ii) generate transcriptional lacZ fusions when inserted into a chromosomal gene in the appropriate orientation, and (iii) allow the rapid cloning in Escherichia coli of chromosomal DNA flanking transposon insertions. The rapid cloning of DNA flanking insertions is possible because the transposon derivatives carry ColE1 replication functions, a cluster of polylinker cloning sites, and antibiotic resistance genes selectable in E. coli (bla in the case of Tn917-LTV1; neo and ble in the case of Tn917-LTV3). The enhanced transposition frequency of Tn917-LTV1 and Tn917-LTV3 (about 100-fold in Bacillus subtilis) is believed to be due to the fortuitous placement of vector-derived promoters upstream from the Tn917 transposase gene. In L. monocytogenes, Tn917-LTV3 transposed at a frequency of 8 x 10(-4) when introduced on a pE194Ts-derived vector and generated at least eight different auxotrophic mutations. Two nonhemolytic insertion mutants of L. monocytogenes were isolated, and DNA flanking the transposon insertions was cloned directly into E. coli, making use of the ColE1 rep functions and neo gene carried by Tn917-LTV3. Both insertions were shown to be within hlyA, the L. monocytogenes hemolysin structural gene. Although Tn917-LTV1 and Tn917-LTV3 were constructed specifically for genetic analysis of L. monocytogenes, their enhanced transposition frequency and convenience for cloning of DNA adjacent to sites of insertions make them the transposon derivatives of choice for insertional mutagenesis in any gram-positive bacteria that support replication of pE194Ts.

Camilli, A; Portnoy, A; Youngman, P

1990-01-01

31

Covalent attachment of lipid vesicles to a fluid supported bilayer allows observation of DNA-mediated vesicle interactions  

PubMed Central

Specific membrane interactions such as lipid vesicle docking and fusion can be mediated by synthetic DNA-lipid conjugates as a model for the protein-driven processes that are ubiquitous in biological systems. Here we present a method of tethering vesicles to a supported lipid bilayer that allows simultaneous deposition of cognate vesicle partners displaying complementary DNA, resulting in well-mixed populations of tethered vesicles that are laterally mobile. Vesicles are covalently attached to a supporting lipid bilayer using a DNA-templated click reaction; then DNA-mediated interactions between tethered vesicles are triggered by spiking the salt concentration. These interactions, such as docking and fusion, can then be observed for individual vesicles as they collide on the surface. The architecture of this new system also permits control over the number of lipid anchors that tether the vesicle to the supporting bilayer. The diffusion coefficient of tethered vesicles anchored by two lipids is approximately 1.6-fold slower than that of vesicles anchored only with a single lipid, consistent with a simple physical model.

van Lengerich, Bettina; Rawle, Robert J.; Boxer, Steven G.

2010-01-01

32

Enabling direct nanoscale observations of biological reactions with dynamic TEM  

SciTech Connect

Biological processes can occur over a wide range of spatial and temporal scales; from femtoseconds to hours and from angstroms to meters. Although no single experimental method can fully cover this entire phase space, many new biological insights can be expected from a better understanding of the processes that occur on the very fast timescales and very small length scales. In this regard, new instruments that use fast x-ray or electron pulses are now available that are expected to reveal new mechanistic insights for macromolecular protein dynamics. To ensure that any observed conformational change is physiologically relevant and not constrained by three-dimensional crystal packing, it would be preferable for experiments to utilize smaller protein samples such as single particles or two-dimensional crystals that mimic the target protein’s native environment. These samples aren’t typically amenable to x-ray analysis, but transmission electron microscopy has successfully imaged such sample geometries for over 40 years and permits data acquisition using both direct imaging and diffraction modes. While conventional transmission electron microscopes (TEM) have only visualized biological samples with atomic resolution in an arrested or frozen state, the recent development of the dynamic TEM (DTEM) extends electron microscopy capabilities into dynamics. A new 2nd generation DTEM that is currently being constructed has the potential to observe live biological processes with unprecedented spatiotemporal resolution by using pulsed electron packets to probe the sample on the micro- and nanosecond timescale. In addition to the enhanced temporal resolution, the DTEM also operates in the pump-probe regime that can permit visualizing reactions propagating in real-time. This article reviews the experimental parameters necessary for coupling DTEM with in situ liquid microscopy to allow direct imaging of protein conformational dynamics in a fully hydrated environment.

Evans, James E.; Browning, Nigel D.

2013-02-18

33

Direct Observational Assessment During Test Sessions and Child Clinical Interviews  

Microsoft Academic Search

Test sessions and child clinical interviews offer opportunities for direct observations of children's behavior in controlled settings. Moreover, standardized instruments for test session and interview observations offer more reliable and valid assessment methods than do anecdotal reports. This article reviews charac- teristics and psychometric properties of three standardized instruments for test session or interview observations: the Guide to Assessment of

Stephanie H. McConaughy

2005-01-01

34

Direct Observation of Two Proton Radioactivity Using Digital Photography  

SciTech Connect

Recently the observation of a new type of spontaneous radioactive decay has been claimed in which two protons are simultaneously ejected by an atomic nucleus from the ground state1,2,3. Experimental data obtained for the extremely neutron-deficient nuclei 45Fe and 54Zn, were interpreted as the first evidence of such a decay mode which has been sought since 1960.4 However, the technique applied in those studies allowed only measurements of the decay time and the total energy released. Particles emitted in the decay were not identified and the conclusions had to be supported by theoretical arguments. Here we show for the first time, directly and unambiguously, that 45Fe indeed disintegrates by two-proton decay. Furthermore, we demonstrate that the decay branch of this isotope leads to various particle emission channels including two-proton and three-proton emission. To achieve this result we have developed a new type of detector V the Optical Time Projection Chamber (OTPC) in which digital photography is applied to nuclear physics for the first time. The detector records images of tracks from charged particles, allowing for their unambiguous identification and the reconstruction of decay events in three dimensions. This new and simple technique provides a powerful method to identify exotic decay channels involving emission of charged particles. It is expected that further studies with the OTPC device will yield important information on nuclei located at and beyond the proton drip-line, thus providing new material for testing and improving models of very unstable atomic nuclei.

Rykaczewski, Krzysztof Piotr [ORNL; Pfutzner, M. [IEP, Warsaw University; Dominik, Wojciech [Warsaw University; Janas, Z. [IEP, Warsaw University; Miernik, K. [IEP, University of Warsaw; Bingham, C. R. [University of Tennessee, Knoxville (UTK); Czyrkowski, Henryk [Warsaw University; Cwiok, Mikolaj [Warsaw University; Darby, Iain [University of Tennessee, Knoxville (UTK); Dabrowski, Ryszard [Warsaw University; Ginter, T. N. [NSCL Michigan State University; Grzywacz, Robert Kazimierz [ORNL; Karny, M. [IEP, Warsaw University; Korgul, A. [IEP, Warsaw University; Kusmierz, Waldemar [Warsaw University; Liddick, Sean [University of Tennessee, Knoxville (UTK); Rajabali, Mustafa [University of Tennessee, Knoxville (UTK); Stolz, A. [NSCL Michigan State University

2007-01-01

35

Direct spectroscopic observation of quantum jumps of a single molecule  

NASA Astrophysics Data System (ADS)

BOHR'S notion of quantum jumps between electronic states of an excited atom has now been demonstrated experimentally for single ions confined in radio-frequency traps and interacting with a driving laser field1-3. In these experiments the fluorescence of a strongly allowed transition was shown to cease abruptly when the ion jumped into a metastable state which was coupled to the common electronic ground state by a weak radiative transition. But attempts to monitor quantum jumps of single molecules have been hampered by the fact that the lifetime of the metastable triplet state was too short in relation to the photon detection rate. By using a system with favourable photophysical parameters-terrylene doped into p-terphenyl crystals4-we have now been able to observe directly quantum jumps between electronic states of single terrylene molecules. In contrast to single atoms, here the quantum jumps occur as non-radiative transitions between states of different multiplicity, and are manifested as interruptions of the fluorescence signal. These results demonstrate how single-molecule spectros-copy can reveal truly quantum-mechanical effects in large polyatomic molecules.

Basché, Th.; Kummer, S.; Bräuchle, C.

1995-01-01

36

Direct Observational Assessment during Test Sessions and Child Clinical Interviews  

ERIC Educational Resources Information Center

Test sessions and child clinical interviews offer opportunities for direct observations of children's behavior in controlled settings. Moreover, standardized instruments for test session and interview observations offer more reliable and valid assessment methods than do anecdotal reports. This article reviews characteristics and psychometric…

McConaughy, Stephanie H.

2005-01-01

37

Retinex Image Processing: Improved Fidelity To Direct Visual Observation  

NASA Technical Reports Server (NTRS)

Recorded color images differ from direct human viewing by the lack of dynamic range compression and color constancy. Research is summarized which develops the center/surround retinex concept originated by Edwin Land through a single scale design to a multi-scale design with color restoration (MSRCR). The MSRCR synthesizes dynamic range compression, color constancy, and color rendition and, thereby, approaches fidelity to direct observation.

Jobson, Daniel J.; Rahman, Zia-Ur; Woodell, Glenn A.

1996-01-01

38

Routine hand hygiene audit by direct observation: has nemesis arrived?  

PubMed

Infection prevention and control experts have expended valuable health service time developing and implementing tools to audit health workers' hand hygiene compliance by direct observation. Although described as the 'gold standard' approach to hand hygiene audit, this method is labour intensive and may be inaccurate unless performed by trained personnel who are regularly monitored to ensure quality control. New technological devices have been developed to generate 'real time' data, but the cost of installing them and using them during routine patient care has not been evaluated. Moreover, they do not provide as much information about the hand hygiene episode or the context in which hand hygiene has been performed as direct observation. Uptake of hand hygiene products offers an inexpensive alternative to direct observation. Although product uptake would not provide detailed information about the hand hygiene episode or local barriers to compliance, it could be used as a continuous monitoring tool. Regular inspection of the data by infection prevention and control teams and clinical staff would indicate when and where direct investigation of practice by direct observation and questioning of staff should be targeted by highly trained personnel to identify local problems and improve practice. PMID:21316122

Gould, D J; Drey, N S; Creedon, S

2011-04-01

39

Direct Observation of PFPE Lubricants on Magnetic Disks  

Microsoft Academic Search

Perfluoropolyether lubricant films on magnetic disks were observed by means of atomic force microscopy (AFM) with a fluoride-coated probe. The lubricant films could be observed directly because the adhesion force was decreased by the anti-wetting effect of the fluoride coating on the probes. We compared the molecular conformation of Z-dol (Mw: 2000, 3000, 6000, 8000) with that of Z-tetraol. Thus,

Hiroshi Tani; Norio Tagawa

2009-01-01

40

Direct Observation of Safety Belt Use in Michigan: Fall 1996.  

National Technical Information Service (NTIS)

Results of a direct observation survey of safety belt use in Michigan for fall of 1996 are reported. In the present survey, 8,907 occupants traveling in four vehicle types (passenger cars, sport-utility vehicles, vans, and pickup trucks) were surveyed bet...

D. W. Eby C. Christoff

1996-01-01

41

Direct Observation of Safety Belt Use in Michigan, Fall 1994.  

National Technical Information Service (NTIS)

Results of a direct observation survey of safety belt use in Michigan for fall of 1994 are reported. Belt use was estimated separately for each vehicle type. Within each vehicle type, belt use by gender, age, road type, day of week, and time of day was es...

D. W. Eby F. M. Streff C. Christoff

1994-01-01

42

Direct Observation of Safety Belt Use In Michigan, Fall 1995.  

National Technical Information Service (NTIS)

Results of a direct observation survey of safety belt use in Michigan for fall of 1995 are reported. In the present survey, 9,867 occupants traveling in four vehicle types (passenger vehicles, sport-utility vehicles, vans, and pick-up trucks) were surveye...

D. W. Eby F. M. Streff C. Christoff

1995-01-01

43

Direct Observation of Magnetic Anisotropy in an Individual Fe4 Single-Molecule Magnet  

NASA Astrophysics Data System (ADS)

We study three-terminal charge transport through individual Fe4 single-molecule magnets. Magnetic anisotropy of the single molecule is directly observed by introducing a spectroscopic technique based on measuring the position of the degeneracy point as a function of gate voltage and applied magnetic field. A nonlinear field-dependence is observed which changes by rotating the sample and is, thus, a direct proof of magnetic anisotropy. The sensitivity of this method allows us to observe small changes in the orientation and magnitude of the anisotropy in different charge states. We find that the easy axes in adjacent states are (almost) collinear.

Burzurí, E.; Zyazin, A. S.; Cornia, A.; van der Zant, H. S. J.

2012-10-01

44

Minimally Invasive Knee Arthroplasty with the Subvastus Approach Allows Rapid Rehabilitation: a Prospective, Biomechanical and Observational Study  

PubMed Central

[Purpose] To study the recovery of patients treated with minimally invasive total knee arthroplasty (TKA) performed via the subvastus approach, and to develop an optimal rehabilitation program for these patients. [Methods] Twenty-two patients (17 females and 5 males; mean age 69.2?years), who received unilateral minimally invasive TKA for osteoarthritis, underwent isometric and isokinetic muscle testing and completed a quality of life questionnaire, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), before and after surgery. Muscle strength and ultrasound tests were repeated 1, 2, 6, and 12 months after surgery. [Results] Strength and range of motion were initially lower in the operated knees but demonstrated no significant difference from the healthy knees after 12 months. Sonographically, joint effusion was greater in the osteoarthritic knees than in the healthy knees at baseline, but no significant difference was observed after 12 months. The mean WOMAC pain, stiffness and function scores all decreased from baseline to 6 months, and then slightly increased at 12 months, but only the function score showed a significant difference compared to baseline. [Conclusions] One year after minimally invasive TKA using a subvastus approach, patients had a good overall prognosis, with prompt functional recovery.

Lin, Tsung-Ching; Wang, Hsing-Kuo; Chen, Jia-Wine; Chiu, Cheng-Ming; Chou, Hsiu-Ling; Chang, Chih-Hung

2013-01-01

45

Direct Observation of Confined Single Chain Dynamics by Neutron Scattering  

NASA Astrophysics Data System (ADS)

Neutron spin echo has revealed the single chain dynamic structure factor of entangled polymer chains confined in cylindrical nanopores with chain dimensions either much larger or smaller than the lateral pore sizes. In both situations, a slowing down of the dynamics with respect to the bulk behavior is only observed at intermediate times. The results at long times provide a direct microscopic measurement of the entanglement distance under confinement. They constitute the first experimental microscopic evidence of the dilution of the total entanglement density in a polymer melt under strong confinement, a phenomenon that so far was hypothesized on the basis of various macroscopic observations.

Martín, J.; Krutyeva, M.; Monkenbusch, M.; Arbe, A.; Allgaier, J.; Radulescu, A.; Falus, P.; Maiz, J.; Mijangos, C.; Colmenero, J.; Richter, D.

2010-05-01

46

Direct observation of single kinesin molecules moving along microtubules  

Microsoft Academic Search

KINESIN is a two-headed motor protein that powers organelle transport along microtubules1. Many ATP molecules are hydro-lysed by kinesin for each diffusional encounter with the micro-tubule2,3. Here we report the development of a new assay in which the processive movement of individual fluorescently labelled kinesin molecules along a microtubule can be visualized directly; this observation is achieved by low-background total

Ronald D. Vale; Takashi Funatsu; Daniel W. Pierce; Laura Romberg; Yoshie Harada; Toshio Yanagida

1996-01-01

47

Direct Observation of the Strange b Baryon Xib-  

Microsoft Academic Search

We report the first direct observation of the strange b baryon Xib-(Xi¯b+). We reconstruct the decay Xib--->J\\/psiXi-, with J\\/psi-->mu+mu-, and Xi--->Lambdapi--->ppi-pi- in pp¯ collisions at s=1.96TeV. Using 1.3fb-1 of data collected by the D0 detector, we observe 15.2±4.4(stat)-0.4+1.9(syst) Xib- candidates at a mass of 5.774±0.011(stat)±0.015(syst)GeV. The significance of the observed signal is 5.5sigma, equivalent to a probability of 3.3×10-8 of

V. M. Abazov; B. Abbott; M. Abolins; B. S. Acharya; M. Adams; T. Adams; E. Aguilo; S. H. Ahn; M. Ahsan; G. D. Alexeev; G. Alkhazov; A. Alton; G. Alverson; G. A. Alves; M. Anastasoaie; L. S. Ancu; T. Andeen; S. Anderson; B. Andrieu; M. S. Anzelc; Y. Arnoud; M. Arov; M. Arthaud; A. Askew; B. Åsman; A. C. S. Assis Jesus; O. Atramentov; C. Autermann; C. Avila; C. Ay; F. Badaud; A. Baden; L. Bagby; B. Baldin; D. V. Bandurin; S. Banerjee; P. Banerjee; E. Barberis; A.-F. Barfuss; P. Bargassa; P. Baringer; J. F. Bartlett; U. Bassler; D. Bauer; S. Beale; A. Bean; M. Begalli; M. Begel; C. Belanger-Champagne; L. Bellantoni; A. Bellavance; J. A. Benitez; S. B. Beri; G. Bernardi; R. Bernhard; L. Berntzon; I. Bertram; M. Besançon; R. Beuselinck; V. A. Bezzubov; P. C. Bhat; V. Bhatnagar; C. Biscarat; G. Blazey; F. Blekman; S. Blessing; D. Bloch; K. Bloom; A. Boehnlein; D. Boline; T. A. Bolton; G. Borissov; K. Bos; T. Bose; A. Brandt; R. Brock; G. Brooijmans; A. Bross; D. Brown; N. J. Buchanan; D. Buchholz; M. Buehler; V. Buescher; S. Burdin; S. Burke; T. H. Burnett; C. P. Buszello; J. M. Butler; P. Calfayan; S. Calvet; J. Cammin; S. Caron; W. Carvalho; B. C. K. Casey; N. M. Cason; H. Castilla-Valdez; S. Chakrabarti; D. Chakraborty; K. M. Chan; A. Chandra; F. Charles; E. Cheu; F. Chevallier; D. K. Cho; S. Cihangir; B. Choudhary; L. Christofek; T. Christoudias; D. Claes; C. Clément; B. Clément; Y. Coadou; M. Corcoran; W. E. Cooper; M.-C. Cousinou; F. Couderc; S. Crépé-Renaudin; D. Cutts; M. Cwiok; H. da Motta; A. Das; G. Davies; K. de; S. J. de Jong; P. de Jong; E. de La Cruz-Burelo; C. de Oliveira Martins; J. D. Degenhardt; F. Déliot; M. Demarteau; R. Demina; D. Denisov; S. P. Denisov; S. Desai; H. T. Diehl; M. Diesburg; A. Dominguez; H. Dong; L. V. Dudko; L. Duflot; S. R. Dugad; D. Duggan; A. Duperrin; J. Dyer; A. Dyshkant; M. Eads; D. Edmunds; J. Ellison; V. D. Elvira; Y. Enari; S. Eno; P. Ermolov; H. Evans; A. Evdokimov; V. N. Evdokimov; A. V. Ferapontov; T. Ferbel; F. Fiedler; F. Filthaut; W. Fisher; H. E. Fisk; M. Ford; M. Fortner; H. Fox; S. Fu; S. Fuess; T. Gadfort; C. F. Galea; E. Gallas; E. Galyaev; C. Garcia; A. Garcia-Bellido; V. Gavrilov; P. Gay; W. Geist; D. Gelé; C. E. Gerber; Y. Gershtein; D. Gillberg; G. Ginther; N. Gollub; B. Gómez; A. Goussiou; P. D. Grannis; H. Greenlee; Z. D. Greenwood; E. M. Gregores; G. Grenier; Ph. Gris; J.-F. Grivaz; A. Grohsjean; S. Grünendahl; M. W. Grünewald; J. Guo; F. Guo; P. Gutierrez; G. Gutierrez; A. Haas; N. J. Hadley; P. Haefner; S. Hagopian; J. Haley; I. Hall; R. E. Hall; L. Han; K. Hanagaki; P. Hansson; K. Harder; A. Harel; R. Harrington; J. M. Hauptman; R. Hauser; J. Hays; T. Hebbeker; D. Hedin; J. G. Hegeman; J. M. Heinmiller; A. P. Heinson; U. Heintz; C. Hensel; K. Herner; G. Hesketh; M. D. Hildreth; R. Hirosky; J. D. Hobbs; B. Hoeneisen; H. Hoeth; M. Hohlfeld; S. J. Hong; R. Hooper; S. Hossain; P. Houben; Y. Hu; Z. Hubacek; V. Hynek; I. Iashvili; R. Illingworth; A. S. Ito; S. Jabeen; M. Jaffré; S. Jain; K. Jakobs; C. Jarvis; R. Jesik; K. Johns; C. Johnson; M. Johnson; A. Jonckheere; P. Jonsson; A. Juste; D. Käfer; S. Kahn; E. Kajfasz; A. M. Kalinin; J. R. Kalk; J. M. Kalk; S. Kappler; D. Karmanov; J. Kasper; P. Kasper; I. Katsanos; D. Kau; R. Kaur; V. Kaushik; R. Kehoe; S. Kermiche; N. Khalatyan; A. Khanov; A. Kharchilava; Y. M. Kharzheev; D. Khatidze; H. Kim; T. J. Kim; M. H. Kirby; M. Kirsch; B. Klima; J. M. Kohli; J.-P. Konrath; M. Kopal; V. M. Korablev; B. Kothari; A. V. Kozelov; D. Krop; A. Kryemadhi; T. Kuhl; A. Kumar; S. Kunori; A. Kupco; T. Kurca; J. Kvita; F. Lacroix; D. Lam; S. Lammers; G. Landsberg; J. Lazoflores; P. Lebrun; W. M. Lee; A. Leflat; F. Lehner; J. Lellouch; V. Lesne; J. Leveque; P. Lewis; J. Li; Q. Z. Li; L. Li; S. M. Lietti; J. G. R. Lima; D. Lincoln; J. Linnemann; V. V. Lipaev; R. Lipton; Y. Liu; Z. Liu; L. Lobo; A. Lobodenko; M. Lokajicek; A. Lounis; P. Love; H. J. Lubatti; A. L. Lyon; A. K. A. Maciel; D. Mackin; R. J. Madaras; P. Mättig; C. Magass; A. Magerkurth; N. Makovec; P. K. Mal; H. B. Malbouisson; S. Malik; V. L. Malyshev; H. S. Mao; Y. Maravin; B. Martin; R. McCarthy; A. Melnitchouk; A. Mendes; L. Mendoza; P. G. Mercadante; Y. P. Merekov; M. Merkin; K. W. Merritt; J. Meyer; A. Meyer; M. Michaut; T. Millet; J. Mitrevski; J. Molina; R. K. Mommsen; N. K. Mondal; R. W. Moore; T. Moulik; G. S. Muanza; M. Mulders; M. Mulhearn; O. Mundal; L. Mundim; E. Nagy; M. Naimuddin; M. Narain; N. A. Naumann; H. A. Neal; J. P. Negret; P. Neustroev; H. Nilsen; A. Nomerotski; S. F. Novaes; T. Nunnemann; V. O'Dell; D. C. O'Neil; G. Obrant; C. Ochando; D. Onoprienko; N. Oshima; J. Osta; R. Otec; G. J. Otero Y Garzón; M. Owen; P. Padley; M. Pangilinan; G. Panov; N. Parashar; S.-J. Park; S. K. Park; J. Parsons; R. Partridge; N. Parua; A. Patwa; G. Pawloski; B. Penning; P. M. Perea; K. Peters; Y. Peters; P. Pétroff; M. Petteni

2007-01-01

48

Microcrack closure in rocks under stress - Direct observation  

NASA Technical Reports Server (NTRS)

Direct observations of the closure of microcracks in rocks under increasing stress are reported. Uniaxial stresses up to 300 bars were applied to untreated and previously heated samples of Westerly granite and Frederick diabase by a small hydraulic press which fit entirely within a scanning electron microscope. Crack closure characteristics are found to depend on crack orientation, with cracks perpendicular to the applied stress closing and those parallel tending to open, as well as crack aspect ratio, crack intersection properties, stress concentrations and surface roughness. Uniaxial and hydrostatic stress measurements are found to be strongly dependent on fracture content as observed by SEM, and the observed hysteresis in strain measurements in the first stress cycles is also related to microscopic processes

Batzle, M. L.; Simmons, G.; Siegfried, R. W.

1980-01-01

49

Direct observation of intermolecular interactions mediated by hydrogen bonding.  

PubMed

Although intermolecular interactions are ubiquitous in physicochemical phenomena, their dynamics have proven difficult to observe directly, and most experiments rely on indirect measurements. Using broadband two-dimensional infrared spectroscopy (2DIR), we have measured the influence of hydrogen bonding on the intermolecular vibrational coupling between dimerized N-methylacetamide molecules. In addition to strong intramolecular coupling between N-H and C=O oscillators, cross-peaks in the broadband 2DIR spectrum appearing upon dimerization reveal strong intermolecular coupling that changes the character of the vibrations. In addition, dimerization changes the effects of intramolecular coupling, resulting in Fermi resonances between high and low-frequency modes. These results illustrate how hydrogen bonding influences the interplay of inter- and intramolecular vibrations, giving rise to correlated nuclear motions and significant changes in the vibrational structure of the amide group. These observations have direct impact on modeling and interpreting the IR spectra of proteins. In addition, they illustrate a general approach to direct molecular characterization of intermolecular interactions. PMID:25053321

De Marco, Luigi; Thämer, Martin; Reppert, Mike; Tokmakoff, Andrei

2014-07-21

50

Direct observation of Kelvin waves excited by quantized vortex reconnection  

PubMed Central

Quantized vortices are key features of quantum fluids such as superfluid helium and Bose–Einstein condensates. The reconnection of quantized vortices and subsequent emission of Kelvin waves along the vortices are thought to be central to dissipation in such systems. By visualizing the motion of submicron particles dispersed in superfluid 4He, we have directly observed the emission of Kelvin waves from quantized vortex reconnection. We characterize one event in detail, using dimensionless similarity coordinates, and compare it with several theories. Finally, we give evidence for other examples of wavelike behavior in our system.

Fonda, Enrico; Meichle, David P.; Ouellette, Nicholas T.; Hormoz, Sahand; Lathrop, Daniel P.

2014-01-01

51

Direct observation of thermal relaxation in artificial spin ice.  

PubMed

We study the thermal relaxation of artificial spin ice with photoemission electron microscopy, and are able to directly observe how such a system finds its way from an energetically excited state to the ground state. On plotting vertex-type populations as a function of time, we can characterize the relaxation, which occurs in two stages, namely a string and a domain regime. Kinetic Monte Carlo simulations agree well with the temporal evolution of the magnetic state when including disorder, and the experimental results can be explained by considering the effective interaction energy associated with the separation of pairs of vertex excitations. PMID:23952441

Farhan, A; Derlet, P M; Kleibert, A; Balan, A; Chopdekar, R V; Wyss, M; Perron, J; Scholl, A; Nolting, F; Heyderman, L J

2013-08-01

52

Direct Observation of Thermal Relaxation in Artificial Spin Ice  

NASA Astrophysics Data System (ADS)

We study the thermal relaxation of artificial spin ice with photoemission electron microscopy, and are able to directly observe how such a system finds its way from an energetically excited state to the ground state. On plotting vertex-type populations as a function of time, we can characterize the relaxation, which occurs in two stages, namely a string and a domain regime. Kinetic Monte Carlo simulations agree well with the temporal evolution of the magnetic state when including disorder, and the experimental results can be explained by considering the effective interaction energy associated with the separation of pairs of vertex excitations.

Farhan, A.; Derlet, P. M.; Kleibert, A.; Balan, A.; Chopdekar, R. V.; Wyss, M.; Perron, J.; Scholl, A.; Nolting, F.; Heyderman, L. J.

2013-08-01

53

Direct observation of local atomic order in a metallic glass  

NASA Astrophysics Data System (ADS)

The determination of the atomic configuration of metallic glasses is a long-standing problem in materials science and solid-state physics. So far, only average structural information derived from diffraction and spectroscopic methods has been obtained. Although various atomic models have been proposed in the past fifty years, a direct observation of the local atomic structure in disordered materials has not been achieved. Here we report local atomic configurations of a metallic glass investigated by nanobeam electron diffraction combined with ab initio molecular dynamics simulation. Distinct diffraction patterns from individual atomic clusters and their assemblies, which have been theoretically predicted as short- and medium-range order, can be experimentally observed. This study provides compelling evidence of the local atomic order in the disordered material and has important implications in understanding the atomic mechanisms of metallic-glass formation and properties.

Hirata, Akihiko; Guan, Pengfei; Fujita, Takeshi; Hirotsu, Yoshihiko; Inoue, Akihisa; Yavari, Alain Reza; Sakurai, Toshio; Chen, Mingwei

2011-01-01

54

Direct observations of the evolution of polar cap ionization patches.  

PubMed

Patches of ionization are common in the polar ionosphere, where their motion and associated density gradients give variable disturbances to high-frequency (HF) radio communications, over-the-horizon radar location errors, and disruption and errors to satellite navigation and communication. Their formation and evolution are poorly understood, particularly under disturbed space weather conditions. We report direct observations of the full evolution of patches during a geomagnetic storm, including formation, polar cap entry, transpolar evolution, polar cap exit, and sunward return flow. Our observations show that modulation of nightside reconnection in the substorm cycle of the magnetosphere helps form the gaps between patches where steady convection would give a "tongue" of ionization (TOI). PMID:23539601

Zhang, Qing-He; Zhang, Bei-Chen; Lockwood, Michael; Hu, Hong-Qiao; Moen, Jøran; Ruohoniemi, J Michael; Thomas, Evan G; Zhang, Shun-Rong; Yang, Hui-Gen; Liu, Rui-Yuan; McWilliams, Kathryn A; Baker, Joseph B H

2013-03-29

55

Direct observation of local atomic order in a metallic glass.  

PubMed

The determination of the atomic configuration of metallic glasses is a long-standing problem in materials science and solid-state physics. So far, only average structural information derived from diffraction and spectroscopic methods has been obtained. Although various atomic models have been proposed in the past fifty years, a direct observation of the local atomic structure in disordered materials has not been achieved. Here we report local atomic configurations of a metallic glass investigated by nanobeam electron diffraction combined with ab initio molecular dynamics simulation. Distinct diffraction patterns from individual atomic clusters and their assemblies, which have been theoretically predicted as short- and medium-range order, can be experimentally observed. This study provides compelling evidence of the local atomic order in the disordered material and has important implications in understanding the atomic mechanisms of metallic-glass formation and properties. PMID:21102454

Hirata, Akihiko; Guan, Pengfei; Fujita, Takeshi; Hirotsu, Yoshihiko; Inoue, Akihisa; Yavari, Alain Reza; Sakurai, Toshio; Chen, Mingwei

2011-01-01

56

Enabling direct nanoscale observations of biological reactions with dynamic TEM  

PubMed Central

Biological processes occur on a wide range of spatial and temporal scales: from femtoseconds to hours and from angstroms to meters. Many new biological insights can be expected from a better understanding of the processes that occur on these very fast and very small scales. In this regard, new instruments that use fast X-ray or electron pulses are expected to reveal novel mechanistic details for macromolecular protein dynamics. To ensure that any observed conformational change is physiologically relevant and not constrained by 3D crystal packing, it would be preferable for experiments to utilize small protein samples such as single particles or 2D crystals that mimic the target protein's native environment. These samples are not typically amenable to X-ray analysis, but transmission electron microscopy has imaged such sample geometries for over 40 years using both direct imaging and diffraction modes. While conventional transmission electron microscopes (TEM) have visualized biological samples with atomic resolution in an arrested or frozen state, the recent development of the dynamic TEM (DTEM) extends electron microscopy into a dynamic regime using pump-probe imaging. A new second-generation DTEM, which is currently being constructed, has the potential to observe live biological processes with unprecedented spatiotemporal resolution by using pulsed electron packets to probe the sample on micro- and nanosecond timescales. This article reviews the experimental parameters necessary for coupling DTEM with in situ liquid microscopy to enable direct imaging of protein conformational dynamics in a fully hydrated environment and visualize reactions propagating in real time.

Evans, James E.; Browning, Nigel D.

2013-01-01

57

Direct microscopic observation of forward osmosis membrane fouling.  

PubMed

This study describes the application of a noninvasive direct microscopic observation method for characterizing fouling of a forward osmosis (FO) membrane. The effect of the draw solution concentration, membrane orientation, and feed spacer on FO fouling was systematically investigated in a cross-flow setup using latex particles as model foulant in the feedwater. Higher draw solution (DS) concentrations (and thus increased flux levels) resulted in dramatic increase in the surface coverage by latex particles, suggesting that the critical flux concept might be applicable even for the osmotically driven FO process. Under identical draw solution concentrations, the active-layer-facing-the-feed-solution orientation (AL-FS) experienced significantly less fouling compared to the alternative orientation. This may be explained by the lower water flux in AL-FS, which is consistent with the critical flux concept. The use of a feed spacer not only dramatically enhanced the initial flux of the FO membrane, but also significantly improved the flux stability during FO fouling. Despite such beneficial effects of using the feed spacer, a significant amount of particle accumulation was found near the spacer filament, suggesting further opportunities for improved spacer design. To the best of the authors' knowledge, this is the first direct microscopic observation study on FO fouling. PMID:20735033

Wang, Yining; Wicaksana, Filicia; Tang, Chuyang Y; Fane, Anthony G

2010-09-15

58

Fostering directly observed treatment in tuberculosis: a program manager's perspective  

PubMed Central

Global Tuberculosis (TB) report (2013) has revealed that an estimated 8.6 million people developed TB of which, India accounts for almost 26% of the cases. These estimates clearly suggest that the country’s efforts to achieve Millennium Development Goal 6 by 2015 have not delivered the desired output. In India, the TB prevention and control activities are supervised and implemented under the Revised National TB Control Program (RNTCP), which recognizes that implementation of a good quality Directly Observed Treatment with Short course chemotherapy (DOTS) is the first priority for TB control. Directly Observed Treatment (DOT) is the key element in DOTS strategy, in which a DOT provider insures and supports the patients in consuming their drugs throughout the course of treatment. In order to meet the country’s vision to achieve universal access of TB care, the RNTCP has launched a “treatment adherence scheme” (public-private partnership scheme). Further, an evidence-based integrated strategy should be formulated for addressing the identified barriers which advocates universal administration of DOT. To conclude, DOT in RNTCP insures long-term adherence to the treatment, with right drugs in right doses, at right intervals and thus plays an indispensable role in improving the outcome indicators of the program and the quality of life in patients.

Shrivastava, Saurabh RamBihariLal; Shrivastava, Prateek Saurabh; Ramasamy, Jegadeesh

2014-01-01

59

Direct observation of the strange b baryon Xib-.  

PubMed

We report the first direct observation of the strange b baryon Xi(b)- (Xi(b)+). We reconstruct the decay Xi(b)- -->J/psiXi-, with J/psi-->mu+mu-, and Xi--->Lambdapi--->ppi-pi- in pp collisions at square root of s =1.96 TeV. Using 1.3 fb(-1) of data collected by the D0 detector, we observe 15.2 +/- 4.4(stat)(-0.4)(+1.9)(syst) Xi(b)- candidates at a mass of 5.774 +/- 0.011(stat) +/- 0.015(syst) GeV. The significance of the observed signal is 5.5 sigma, equivalent to a probability of 3.3 x 10(-8) of it arising from a background fluctuation. Normalizing to the decay Lambda(b)-->J/psiLambda, we measure the relative rate sigma(Xi(b-) x B(Xi)b})- -->J/psiXi-)/sigma(Lambda(b)) x B(Lambda(b)-->J/psiLambda) = 0.28+/-0.09(stat)(-0.08)(+0.09)(syst). PMID:17930744

Abazov, V M; Abbott, B; Abolins, M; Acharya, B S; Adams, M; Adams, T; Aguilo, E; Ahn, S H; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Anastasoaie, M; Ancu, L S; Andeen, T; Anderson, S; Andrieu, B; Anzelc, M S; Arnoud, Y; Arov, M; Arthaud, M; Askew, A; Asman, B; Assis Jesus, A C S; Atramentov, O; Autermann, C; Avila, C; Ay, C; Badaud, F; Baden, A; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, S; Banerjee, P; Barberis, E; Barfuss, A-F; Bargassa, P; Baringer, P; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Bellavance, A; Benitez, J A; Beri, S B; Bernardi, G; Bernhard, R; Berntzon, L; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Biscarat, C; Blazey, G; Blekman, F; Blessing, S; Bloch, D; Bloom, K; Boehnlein, A; Boline, D; Bolton, T A; Borissov, G; Bos, K; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Buchanan, N J; Buchholz, D; Buehler, M; Buescher, V; Burdin, S; Burke, S; Burnett, T H; Buszello, C P; Butler, J M; Calfayan, P; Calvet, S; Cammin, J; Caron, S; Carvalho, W; Casey, B C K; Cason, N M; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chan, K; Chandra, A; Charles, F; Cheu, E; Chevallier, F; Cho, D K; Choi, S; Choudhary, B; Christofek, L; Christoudias, T; Cihangir, S; Claes, D; Clément, C; Clément, B; Coadou, Y; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M-C; Crépé-Renaudin, S; Cutts, D; Cwiok, M; da Motta, H; Das, A; Davies, G; De, K; de Jong, S J; de Jong, P; De La Cruz-Burelo, E; De Oliveira Martins, C; Degenhardt, J D; Déliot, F; Demarteau, M; Demina, R; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Dominguez, A; Dong, H; Dudko, L V; Duflot, L; Dugad, S R; Duggan, D; Duperrin, A; Dyer, J; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Ermolov, P; Evans, H; Evdokimov, A; Evdokimov, V N; Ferapontov, A V; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Ford, M; Fortner, M; Fox, H; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Gallas, E; Galyaev, E; Garcia, C; Garcia-Bellido, A; Gavrilov, V; Gay, P; Geist, W; Gelé, D; Gerber, C E; Gershtein, Y; Gillberg, D; Ginther, G; Gollub, N; Gómez, B; Goussiou, A; Grannis, P D; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, Ph; Grivaz, J-F; Grohsjean, A; Grünendahl, S; Grünewald, M W; Guo, J; Guo, F; Gutierrez, P; Gutierrez, G; Haas, A; Hadley, N J; Haefner, P; Hagopian, S; Haley, J; Hall, I; Hall, R E; Han, L; Hanagaki, K; Hansson, P; Harder, K; Harel, A; Harrington, R; Hauptman, J M; Hauser, R; Hays, J; Hebbeker, T; Hedin, D; Hegeman, J G; Heinmiller, J M; Heinson, A P; Heintz, U; Hensel, C; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoeth, H; Hohlfeld, M; Hong, S J; Hooper, R; Hossain, S; Houben, P; Hu, Y; Hubacek, Z; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jakobs, K; Jarvis, C; Jesik, R; Johns, K; Johnson, C; Johnson, M; Jonckheere, A; Jonsson, P; Juste, A; Käfer, D; Kahn, S; Kajfasz, E; Kalinin, A M; Kalk, J R; Kalk, J M; Kappler, S; Karmanov, D; Kasper, J; Kasper, P; Katsanos, I; Kau, D; Kaur, R; Kaushik, V; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Y M; Khatidze, D; Kim, H; Kim, T J; Kirby, M H; Kirsch, M; Klima, B; Kohli, J M; Konrath, J-P; Kopal, M; Korablev, V M; Kothari, B; Kozelov, A V; Krop, D; Kryemadhi, A; Kuhl, T; Kumar, A; Kunori, S; Kupco, A; Kurca, T; Kvita, J; Lacroix, F; Lam, D; Lammers, S; Landsberg, G; Lazoflores, J; Lebrun, P; Lee, W M; Leflat, A; Lehner, F; Lellouch, J; Lesne, V; Leveque, J; Lewis, P; Li, J; Li, Q Z; Li, L; Lietti, S M; Lima, J G R; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Y; Liu, Z; Lobo, L; Lobodenko, A; Lokajicek, M; Lounis, A; Love, P; Lubatti, H J; Lyon, A L; Maciel, A K A; Mackin, D; Madaras, R J; Mättig, P; Magass, C; Magerkurth, A; Makovec, N; Mal, P K; Malbouisson, H B; Malik, S; Malyshev, V L; Mao, H S; Maravin, Y; Martin, B; McCarthy, R; Melnitchouk, A; Mendes, A; Mendoza, L; Mercadante, P G; Merekov, Y P; Merkin, M; Merritt, K W; Meyer, J; Meyer, A; Michaut, M; Millet, T; Mitrevski, J; Molina, J; Mommsen, R K; Mondal, N K; Moore, R W; Moulik, T; Muanza, G S; Mulders, M; Mulhearn, M; Mundal, O; Mundim, L; Nagy, E; Naimuddin, M; Narain, M; Naumann, N A; Neal, H A; Negret, J P; Neustroev, P; Nilsen, H; Nomerotski, A; Novaes, S F; Nunnemann, T; O'Dell, V; O'Neil, D C; Obrant, G; Ochando, C; Onoprienko, D; Oshima, N; Osta, J; Otec, R; Otero y Garzón, G J; Owen, M; Padley, P; Pangilinan, M; Panov, G; Parashar, N; Park, S-J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Pawloski, G; Penning, B; Perea, P M; Peters, K; Peters, Y; Pétroff, P; Petteni, M; Piegaia, R; Piper, J; Pleier, M-A; Podesta-Lerma, P L M; Podstavkov, V M

2007-08-01

60

Direct and Semi-direct Radiative Responses to Observation-Constrained Aerosol Absorption over S Asia  

NASA Astrophysics Data System (ADS)

Climate impacts of aerosols over S. Asia have been studied extensively in both models and observations. However, discrepancies between observed and modeled aerosol concentrations and optical properties have hindered our understanding of the aerosol influences on the regional monsoon circulation and rainfall. We present an in-depth examination of direct and semi-direct radiative responses due to aerosols on the latitudinal heating gradient and cloud distribution, with observational constraints on solar absorption by aerosols. Regional distributions of aerosol concentration are simulated with a 12-km regional climate model (WRF-Chem) driven by the NCEP analysis data from August 2011 to March 2012. During this time period, the ground-based measurements of aerosols and clouds, surface radiation, water vapor, and temperature were taken at Nainital (29.38°N, 79.45°E) during the DOE Ganges Valley Experiment (GVAX). This data set, which is available at high temporal resolution (hourly), is used to evaluate and constrain the simulated wavelength dependence of aerosol absorption and the correlation with changes in surface radiation, cloud base height and liquid water content for the entire post-monsoon period. The analysis is extended to a regional scale by comparing with satellite observation of absorbing aerosol optical depth (OMI) and cloud properties (MODIS). Preliminary results show good agreement in monthly variations of simulated and observed aerosol optical depth (AOD) except during periods of high observed AOD. Initial analysis indicates a possible local origin for the aerosols that is not captured in the model at present. Furthermore, analysis of the spectrally resolved aerosol absorption measurements indicates that these local aerosols exhibit strong absorption in near-UV and visible wavelengths. A large fraction of increased absorption during October and November (local fall harvest season) is attributable to the super-micron sized aerosol particles. In addition, much higher ceilometer lowest cloud base height (>5 km) is observed coincident with high aerosol absorption coefficient (>50 Mm-1 at 528nm), which may be indicative of the semi-direct 'burning off' effect due to absorbing aerosols, as the prevailing lowest cloud base height observed is below 3km from the ground. In comparison, the model-simulated aerosol absorption is significantly lower around 15 Mm-1 during these time periods and the model calculated OC/BC ratios are about 2~4 also smaller than observations. This may likely suggest an underestimate of absorbing organics from the biomass burning or biogenic sources. In the presentation, we will present the model sensitivity studies of aerosol absorption constrained by the observed absorption AOD and spectral dependence, and discuss the subsequent changes in the simulated atmospheric heating rates and cloud distributions over this region.

Feng, Y.; Kotamarthi, V. R.; Manoharan, V.

2013-12-01

61

Direct observation of athermal photofluidisation in azo-polymer films.  

PubMed

The surface relief gratings (SRGs) can be generated when azo-polymer films are exposed to laser beam interference as a result of mass migration. Despite considerable research effort over the past two decades this complex phenomenon remains incompletely understood. Here we show, for the first time, the athermal photofluidisation of azo-polysiloxane films exposed to 488 nm light, directly monitored by optical microscopy. A process of surface relief erasure occurring in parallel with its inscription was also observed during laser irradiation. We therefore propose a new mechanism of SRG formation, based on three different processes: (1) the polymer photo-fluidization in illuminated regions, (2) the mass displacement from illuminated to dark regions and (3) the inverse mass displacement, from dark to illuminated regions. The mechanical properties of the films during UV light irradiation were investigated by classical rheology and, for the first time, by using amplitude modulation-frequency modulation atomic force microscopy (AM-FM AFM). PMID:24833017

Hurduc, Nicolae; Donose, Bogdan C; Macovei, Alina; Paius, Cristina; Ibanescu, Constanta; Scutaru, Dan; Hamel, Matthieu; Branza-Nichita, Norica; Rocha, Licinio

2014-06-11

62

Direct Observation of Cotranscriptional Folding in an Adenine Riboswitch  

PubMed Central

Growing RNA chains fold cotranscriptionally as they are synthesized by RNA polymerase (RNAP). Riboswitches, which regulate gene expression by adopting alternative RNA folds, are sensitive to cotranscriptional events. We developed an optical-trapping assay to follow the cotranscriptional folding of a nascent RNA, and used it to monitor individual transcripts of the pbuE adenine riboswitch, visualizing distinct folding transitions. We report a particular folding signature for the riboswitch aptamer whose presence directs the gene-regulatory transcription outcome, and we measured the termination frequency as a function of adenine level and tension applied to the RNA. Our results demonstrate that the outcome is kinetically controlled. These experiments furnish a means to observe conformational switching in real time, and enable the precise mapping of events during cotranscriptional folding.

Frieda, Kirsten L.; Block, Steven M.

2012-01-01

63

Direct observation of magnetic cycles in Sun-like stars  

NASA Astrophysics Data System (ADS)

A sample of 19 solar-type stars, probing masses between 0.6 and 1.4 solar masses and rotation periods between 3.4 and 43 days, was regularly observed using the NARVAL spectropolarimeter at Telescope Bernard Lyot (Pic du Midi, France) between 2007 and 2011. The Zeeman-Doppler Imaging technique is employed to reconstruct the large-scale photospheric magnetic field structure of the targets and investigate its long-term temporal evolution. We present here the first results of this project with the observation of short magnetic cycles in several stars, showing up a succession of polarity reversals over the timespan of our monitoring. Preliminary trends suggest that short cycles are more frequent for stellar periods below a dozen days and for stellar masses above about one solar mass. The cycles lengths unveiled by the direct tracking of polarity switches are significantly shorter than those derived from previous studies based on chromospheric activity monitoring, suggesting the coexistence of several magnetic timescales in a same star.

Morgenthaler, A.; Petit, P.; Morin, J.; Aurière, M.; Dintrans, B.; Konstantinova-Antova, R.; Marsden, S.

2011-12-01

64

Direct observation, study, and control of molecular superrotors.  

PubMed

Extremely fast rotating molecules whose rotational energy is comparable with the molecular bond strength are known as "superrotors." It has been speculated that superrotors may exhibit a number of unique properties, yet only indirect evidence of these molecular objects has been reported to date. Here we demonstrate the first direct observation of molecular superrotors by detecting coherent unidirectional molecular rotation with extreme frequencies exceeding 10 THz. The technique of an "optical centrifuge" is used to control the degree of rotational excitation in an ultrabroad range of rotational quantum numbers, reaching as high as N=95 in oxygen and N=60 in nitrogen. State-resolved detection enables us to determine the shape of the excited rotational wave packet and quantify the effect of centrifugal distortion on the rotational spectrum. Femtosecond time resolution reveals coherent rotational dynamics with increasing coherence times at higher angular momentum. We demonstrate that molecular superrotors can be created and observed in dense samples under normal conditions where the effects of ultrafast rotation on many-body interactions, intermolecular collisions, and chemical reactions can be readily explored. PMID:24702361

Korobenko, Aleksey; Milner, Alexander A; Milner, Valery

2014-03-21

65

Direct observation of episodic growth in an abyssal xenophyophore (Protista)  

NASA Astrophysics Data System (ADS)

Three specimens of the xenophyophore Reticulammina labyrinthica were photographed on the Madeira Abyssal Plain (31°6.1'N, 21°10.9'W; 4944 m) using the Bathysnap time-lapse camera system. During the 8 month observation period, the specimens underwent an estimated 3-10 fold increase in volume. Growth occurred episodically in several distinct phases, each lasting 2-3 days, during which sediment was collected and incorporated into the test. These phases were separated by fairly regular periods of about 2 months when the organisms showed little obvious activity. The growth phases were approximately synchronous between specimens. However, it is not clear whether the periodicity and apparent synchronization of these events resulted from an external (environmental) cue or whether growth is internally controlled and the synchronization arose by chance. These unique observations, which represent the first direct measurement of growth in any abyssal organism living outside a hydrothermal vent field, suggest that xenophyophores combine test growth with deposit feeding. The tests appear to grow more quickly, and to be more active, dynamic structures, than previously believed.

Gooday, A. J.; Bett, B. J.; Pratt, D. N.

1993-11-01

66

Direct observation of the spin-dependent Peltier effect.  

PubMed

The Peltier coefficient describes the amount of heat that is carried by an electrical current when it passes through a material. When two materials with different Peltier coefficients are placed in contact with one another, the Peltier effect causes a net flow of heat either towards or away from the interface between them. Spintronics describes the transport of electric charge and spin angular momentum by separate spin-up and spin-down channels in a device. The observation that spin-up and spin-down charge transport channels are able to transport heat independently of each other has raised the possibility that spin currents could be used to heat or cool the interface between materials with different spin-dependent Peltier coefficients. Here, we report the direct observation of the heating and cooling of such an interface by a spin current. We demonstrate this spin-dependent Peltier effect in a spin-valve pillar structure that consists of two ferromagnetic layers separated by a non-ferromagnetic metal. Using a three-dimensional finite-element model, we extract spin-dependent Peltier coefficients in the range -0.9 to -1.3 mV for permalloy. The magnetic control of heat flow could prove useful for the cooling of nanoscale electronic components or devices. PMID:22306839

Flipse, J; Bakker, F L; Slachter, A; Dejene, F K; van Wees, B J

2012-03-01

67

Using direct clinical observation to assess the quality of cesarean delivery in Afghanistan: an exploratory study  

PubMed Central

Background As part of a National Emergency Obstetric and Newborn Care (EmONC) Needs Assessment, a special study was undertaken in July 2010 to examine the quality of cesarean deliveries in Afghanistan and examine the utility of direct clinical observation as an assessment method in low-resource settings. Methods This cross-sectional assessment of the quality of cesareans at 14 facilities in Afghanistan included a survey of surgeons regarding their routine cesarean practices, direct observation of 29 cesarean deliveries and comparison of observations with facility records for 34 additional cesareans conducted during the 3 days prior to the observation period at each facility. For both observed cases and record reviews, we assessed time intervals between specified points of care-arrival to the ward, first evaluation, detection of a complication, decision for cesarean, incision, and birth. Results All time intervals with the exception of “decision to skin incision” were longer in the record reviews than in observed cases. Prior cesarean was the most common primary indication for all cases. All mothers in both groups observed survived through one hour postpartum. Among newborns there were two stillbirths (7%) in observed births and seven (21%) record reviews. Although our sample is too small to show statistical significance, the difference is noteworthy. In six of the reviewed cesareans resulting in stillbirth, a fetal heart rate was recorded in the operating theater, although four were recorded as macerated. For the two fresh stillbirths, the cesarean surgeries were recorded as scheduled and not urgent. Conclusions Direct observation of cesarean deliveries enabled us to assess a number of preoperative, postoperative, and intraoperative procedures that are often not described in medical records in low resource settings. Comparison of observations with findings from provider interviews and facility records allowed us to infer whether observed practices were typical of providers and facilities and detect potential Hawthorne effects.

2014-01-01

68

Directly observed treatment, short course in tuberculous meningitis: Indian perspective  

PubMed Central

Background: Effectiveness of intermittent short course chemotherapy for tuberculous meningitis (TBM) has not been well studied. There are scarce reported studies on this issue in the world literature. Neurologists all over India are reluctant to accept Directly Observed Treatment Short course (DOTS) for TBM since its introduction in India. Aim: We did a prospective study to assess effectiveness of Revised National TB Control Program (RNTCP-DOTS) regimes among TBM patients. Materials and Methods: In this study we include the TBM patients admitted from September 2008 to March 2011. All were referred to RNTCP for treatment. Diagnostic Algorithm as per RNTCP guidelines was strictly followed and treatment outcome and follow-up status were recorded. We exclude HIV and pediatric age group. Results: A total of 42 cases registered for DOTS regimen were included in the study, of which 35 completed the treatment (83%). All the patients were started with DOTS but finally 78% received actual DOTS. All patients were given 9 months intermitted regimen as per RNTCP guidelines. Seven patients died during the treatment (16%). Conclusion: We found intermitted short course chemotherapy was effective in TBM.

Sharma, Shri Ram; Lynrah, Kyrshang G.; Sharma, Nalini; Lyngdoh, Monaliza

2013-01-01

69

[Directly observed anti-retroviral therapy amongst female inmates].  

PubMed

Objectives: It is considered that the gold standard for success in HAART is adherence. To improve adherence amongst inmates with HIV-AIDS, the use of directly observed treatment (DOT) is proposed using the tuberculosis treatment model. Material and methods: HIV positive female patients with ARVT criteria who voluntarily participated were used for the study. The initial and final CD4 cell count and HIV viral load were the principal data used for assessment purposes. Results: 52 women with an average age of 34 years were studied, with an average HIV infection time span of between 1 and 20 years. Initial CD4 cell count of <100 copies/mL in 16 patients (30.7%) and an equivalent final count in 4 patients (7.6%) were found. Initial undetectable viral loads were not found in any patient, while final undetectable viral loads were found in 33 (63.4%). 21% of patients had opportunistic infections. The most important of these was tuberculosis, followed by HCV co-infection. The most frequently used ARVT schedule was two NRTI with one NNTRI. Conclusions: The application of DOT strategy to ARVT was effective amongst our patients, as shown by the increase in CD4 counts and the increased number of patients with reductions in viral loads to undetectable levels. While it is a tool that is not easy to use for cases of chronic treatment, we do consider it to be useful for prison inmates. PMID:23128472

de Carolis, L; Wainstein, C

2009-02-01

70

New observables for direct detection of axion dark matter  

NASA Astrophysics Data System (ADS)

We propose new signals for the direct detection of ultralight dark matter such as the axion. Axion or axionlike particle dark matter may be thought of as a background, classical field. We consider couplings for this field which give rise to observable effects including a nuclear electric dipole moment, and axial nucleon and electron moments. These moments oscillate rapidly with frequencies accessible in the laboratory, ˜ kilohertz to gigahertz, given by the dark matter mass. Thus, in contrast to WIMP detection, instead of searching for the hard scattering of a single dark matter particle, we are searching for the coherent effects of the entire classical dark matter field. We calculate current bounds on such time-varying moments and consider a technique utilizing NMR methods to search for the induced spin precession. The parameter space probed by these techniques is well beyond current astrophysical limits and significantly extends laboratory probes. Spin precession is one way to search for these ultralight particles, but there may well be many new types of experiments that can search for dark matter using such time-varying moments.

Graham, Peter W.; Rajendran, Surjeet

2013-08-01

71

Direct observation of interface instability during crystal growth  

NASA Technical Reports Server (NTRS)

The general aim of this investigation was to study interface stability and solute segregation phenomena during crystallization of a model system. Emphasis was to be placed on direct observational studies partly because this offered the possibility at a later stage of performing related experiments under substantially convection-free conditions in the space shuttle. The major achievements described in this report are: (1) the development of a new model system for fundamental studies of crystal growth from the melt and the measurement of a range of material parameters necessary for comparison of experiment with theory. (2) The introduction of a new method of measuring segregation coefficient using absorption of a laser beam by the liquid phase. (3) The comparison of segregation in crystals grown by gradient freezing and by pulling from the melt. (4) The introduction into the theory of solute segregation of an interface field term and comparison with experiment. (5) The introduction of the interface field term into the theories of constitutional supercooling and morphological stability and assessment of its importance.

Tiller, W. A.; Feigelson, R. S.; Elwell, D.

1982-01-01

72

Degassing-induced crystallization in basalts: direct experimental observations  

NASA Astrophysics Data System (ADS)

Degassing of magma increases its liquidus temperature and can thus trigger crystal growth. This can drastically increase magma viscosity and exert a key control on eruptive dynamics in a range of magma compositions. To investigate the process we have used a microscope and heated stage to obtain the first direct observations of degassing-driven crystal growth in natural basaltic melts at magmatic temperatures. We heated samples from Mt. Etna, Italy (0.39 wt.% H2O), and Kilauea, Hawaii (0.18 wt.% H2O) in air at atmospheric pressure to temperatures between 1190 and 1270 °C. Samples were held isothermally for 0.5 to 17 hours before cooling to sub-solidus temperatures. Bubble growth above 900 °C indicated volatile exsolution during heating. Isothermal conditions produced numerous new plagioclase crystals in the Etna sample, which grew to ?160 ?m at maximum rates of 5.2 x 10-6 to 1.8 x 10-5 cm s-1. The dwell temperature determined both crystal growth rates and morphologies (tabular to spherulitic). As equilibrium was approached after 20 minutes crystal growth slowed dramatically. Few new crystals appeared in the H2O-poor Kilauea sample, and maximum growth rates of 1.7 to 6.5 x 10-6 cm s-1 were determined. Pre-existing crystal textures strongly influenced crystal nucleation and growth during cooling, which highlights the importance of studying natural rather than experimental samples. Our results indicate that, when melts are sufficiently H2O-rich, degassing can indeed trigger rapid crystal growth. The resultant changes in the texture, and hence rheology, of erupting magma could exert important controls on eruption dynamics.

Applegarth, L. J.; Tuffen, H.; James, M. R.; Cashman, K.; Pinkerton, H.

2012-12-01

73

Direct Observation of the Controlled Magnetization Reversal Processes in Py/Al/Py Assymmetric Ring Stacks  

SciTech Connect

Electron holographic experiments were performed to study the magnetization reversal process of patterned Py/Al/Py (20nm/20nm/10nm) asymmetric ring stacks. By changing the in-plane field applied perpendicular to the ring's symmetric axis, we directly observed the vortex-based magnetization reversal process through controlled domain wall motion and annihilation. The two magnetic layers were found to switch at different critical fields, leading to the existence of various distinct domain state combinations. Quantitative agreement was obtained between measured phase shifts and those derived from micromagnetic calculations, which allows us to resolve the layer-by-layer magnetic behavior as a function of applied external field.

Huang, L.; Schofield, M.A.; Zhu, Y.

2009-07-27

74

Observation of direct processes in photoproduction at HERA  

Microsoft Academic Search

Jets in photoproduction events have been studied with the ZEUS detector for gammap centre-of-mass energies ranging from 130 to 250 GeV. The inclusive jet distributions give evidence for the dominance of resolved photon interactions. In the di-jet sample the direct processes are for the first time clearly isolated. Di-jet cross sections for the resolved and direct processes are given in

M. Derrick; D. Krakauer; S. Magill; B. Musgrave; J. Repond; S. Repond; R. Stanek; R. L. Talaga; J. Thron; F. Arzarello; R. Ayad; G. Bari; M. Basile; L. Bellagamba; D. Boscherini; A. Bruni; G. Bruni; P. Bruni; G. Cara Romeo; G. Castellini; M. Chiarini; L. Cifarelli; F. Cindolo; F. Ciralli; A. Contin; C. del Papa; S. D'Auria; F. Frasconi; P. Giusti; G. Iacobucci; G. Laurenti; G. Levi; Q. Lin; G. Maccarrone; A. Margotti; T. Massam; R. Nania; C. Nemoz; F. Palmonari; G. Sartorelli; R. Timellini; Y. Zamora Garcia; A. Zichichi; A. Bargende; J. Crittenden; K. Desch; B. Diekmann; T. Doeker; L. Feld; A. Frey; M. Geerts; G. Geitz; H. Hartmann; D. Haun; K. Heinloth; E. Hilger; H.-P. Jakob; U. F. Katz; S. Kramarczyk; M. Kückes; A. Mass; S. Mengel; J. Mollen; H. Müsch; E. Paul; R. Schattevoy; J.-L. Schneider; D. Schramm; R. Wedemeyer; A. Cassidy; D. G. Cussans; N. Dyce; B. Foster; S. George; R. Gilmore; G. P. Heath; H. F. Heath; M. Lancaster; T. J. Llewellyn; C. J. S. Morgado; J. A. O'Mara; R. J. Tapper; S. S. Wilson; R. Yoshida; R. R. Rau; M. Arneodo; M. Schioppa; G. Susinno; A. Bernstein; A. Caldwell; I. Gialas; J. A. Parsons; S. Ritz; F. Sciulli; P. B. Straub; L. Wai; S. Yang; P. Borzemski; J. Chwastowski; A. Eskreys; K. Piotrzkowski; M. Zachara; L. Zawiejski; L. Adamczyk; B. Bednarek; K. Eskreys; K. Jelen; D. Kisielewska; T. Kowalski; E. Rulikowska-Zarebska; L. Suszycki; J. Zajc; T. Kedzierski; A. Kotanski; M. Przybycien; L. A. T. Bauerdick; U. Behrens; J. K. Bienlein; S. Böttcher; C. Coldewey; G. Drews; M. Flasinski; I. Fleck; D. J. Gilkinson; P. Göttlicher; B. Gutjahr; T. Haas; L. Hagge; W. Hain; D. Hasell; H. Heßling; H. Hultschig; P. Joos; M. Kasemann; R. Klanner; W. Koch; L. Köpke; U. Kötz; H. Kowalski; W. Kröger; J. Krüger; J. Labs; A. Ladage; M. Löhr; M. Löwe; D. Lüke; J. Mainusch; O. Manczak; M. Momayezi; J. S. T. Ng; S. Nickel; D. Notz; K.-U. Pösnecker; M. Rohde; J. Roldán; U. Schneekloth; J. Schroeder; W. Schulz; F. Selonke; E. Stiliaris; T. Tsurugai; W. Vogel; D. Westphal; G. Wolf; C. Youngman; H. J. Grabosch; A. Leich; A. Meyer; C. Rethfeldt; S. Schlenstedt; G. Barbagli; M. Nuti; P. Pelfer; G. Anzivino; S. de Pasquale; S. Qian; L. Votano; A. Bamberger; A. Freidhof; T. Poser; S. Söldner-Rembold; G. Theisen; T. Trefzger; N. H. Brook; P. J. Bussey; A. T. Doyle; J. R. Forbes; V. A. Jamieson; C. Raine; D. H. Saxon; M. Stavrianakou; A. S. Wilson; H. Brückmann; A. Dannemann; U. Holm; D. Horstmann; H. Kammerlocher; B. Krebs; T. Neumann; R. Sinkus; K. Wick; A. Fürtjes; E. Lohrmann; J. Milewski; M. Nakahata; N. Pavel; G. Poelz; W. Schott; J. Terron; F. Zetsche; T. C. Bacon; R. Beuselinck; I. Butterworth; E. Gallo; V. L. Harris; K. R. Long; D. B. Miller; A. Prinias; J. K. Sedgbeer; A. Vorvolakos; A. Whitfield; T. Bienz; H. Kreutzmann; U. Mallik; E. McCliment; M. Roco; M. Z. Wang; P. Cloth; D. Filges; S. H. An; S. M. Hong; C. O. Kim; T. Y. Kim; S. W. Nam; S. K. Park; M. H. Suh; S. H. Yon; R. Imlay; S. Kartik; H.-J. Kim; R. R. McNeil; W. Metcalf; V. K. Nadendla; F. Barreiro; G. Cases; L. Hervás; L. Labarga; J. del Peso; J. F. de Trocóniz; F. Ikraiam; J. K. Mayer; G. R. Smith; F. Corriveau; D. S. Hanna; J. Hartmann; L. W. Hung; J. N. Lim; C. G. Matthews; J. W. Mitchell; P. M. Patel; L. E. Sinclair; D. G. Stairs; M. St. Laurent; R. Ullmann; G. L. Bashindzhagyan; P. F. Ermolov; L. K. Gladilin; Y. A. Golubkov; V. A. Kuzmin; E. N. Kuznetsov; A. A. Savin; A. G. Voronin; N. P. Zotov; S. Bentvelsen; M. Botje; A. Dake; J. Engelen; P. de Jong; M. de Kamps; P. Kooijman; A. Kruse; H. van der Lugt; V. O'dell; A. Tenner; H. Tiecke; H. Uijterwaal; M. Vreeswijk; L. Wiggers; E. de Wolf; R. van Woudenberg; B. Bylsma; L. S. Durkin; K. Honscheid; C. Li; T. Y. Ling; K. W. McLean; W. N. Murray; I. H. Park; T. A. Romanowski; R. Seidlein; D. Bailey; G. A. Blair; A. Byrne; R. J. Cashmore; A. M. Cooper-Sarkar; R. C. E. Devenish; N. Harnew; T. Khatri; P. Luffman; P. Morawitz; J. Nash; N. C. Roocroft; R. Walczak; F. F. Wilson; T. Yip; G. Abbiendi; A. Bertolin; R. Brugnera; R. Carlin; F. dal Corso; M. de Giorgi; U. Dosselli; F. Gasparini; S. Limentani; M. Morandin; M. Posocco; L. Stanco; R. Stroili; C. Voci; J. Bulmahn; J. M. Butterworth; R. G. Feild; B. Y. Oh; J. J. Whitmore; U. Contino; G. D'Agostini; M. Guida; M. Iori; S. M. Mari; G. Marini; M. Mattioli; A. Nigro; J. C. Hart; N. A. McCubbin; K. Prytz; T. P. Shah; T. L. Short; E. Barberis; N. Cartiglia; C. Heusch; M. van Hook; B. Hubbard; W. Lockman; H. F.-W. Sadrozinski; A. Seiden; D. Zer-Zion; E. Badura; J. Biltzinger; R. J. Seifert; A. H. Walenta; G. Zech; S. Dagan; A. Levy; T. Hasegawa; M. Hazumi; T. Ishii; S. Kasai; M. Kuze; S. Mine; Y. Nagasawa; T. Nagira; M. Nakao; H. Okuno; I. Suzuki; K. Tokushuku; S. Yamada; Y. Yamazaki; M. Chiba; R. Hamatsu; T. Hirose; K. Homma; S. Kitamura; S. Nagayama; Y. Nakamitsu; R. Cirio; M. Costa; M. I. Ferrero

1994-01-01

75

Observe how the Coriolis effect influences wind direction  

NSDL National Science Digital Library

This animated series of satellite images shows Earth science students how the Coriolis effect causes winds in the Northern Hemisphere to veer to the right of their predicted course. Movie controls allow students to repeat, pause, or step through the animation, which can give students more time to analyze the images. Copyright 2005 Eisenhower National Clearinghouse

Education, Terc. C.; Littell, Mcdougal

2003-01-01

76

Direct Observation of Magnetic Vortices in Superconductors Using Electron Waves  

Microsoft Academic Search

The development of a coherent field-emission electron beam has made it possible to observe microscopic magnetic lines of force by detecting the electron-wave phase shifts that are due to vector potentials. Electron-holographic interference microscopy has been used to observe magnetic lines of force of magnetic vortices in superconductors, and Lorentz microscopy has been used to observe the dynamics of the

Akira Tonomura

1998-01-01

77

Determination of acceleration mechanism characteristics directly and nonparametrically from observations: Application to supernova remnants  

NASA Astrophysics Data System (ADS)

We have developed an inversion method for determination of the characteristics of the acceleration mechanism directly and nonparametrically from observations, in contrast to the usual forward fitting of parametric model variables to observations. In two recent papers [V. Petrosian and Q. Chen, Astrophys. J. 712, L131 (2010); Q. Chen and V. Petrosian, Astrophys. J. 777, 33 (2013)], we demonstrated the efficacy of this inversion method by its application to acceleration of electrons in solar flares based on stochastic acceleration by turbulence. Here we explore its application for determining the characteristics of shock acceleration in supernova remnants (SNRs) based on the electron spectra deduced from the observed nonthermal radiation from SNRs and the spectrum of the cosmic ray electrons observed near the Earth. These spectra are related by the process of escape of the electrons from SNRs and energy loss during their transport in the Galaxy. Thus, these observations allow us to determine spectral characteristics of the momentum and pitch angle diffusion coefficients, which play crucial roles in both direct acceleration by turbulence and in high Mach number shocks. Assuming that the average electron spectrum deduced from a few well-known SNRs is representative of those in the solar neighborhood, we find interesting discrepancies between our deduced forms for these coefficients and those expected from well-known wave-particle interactions. This may indicate that the standard assumptions made in the treatment of shock acceleration need revision. In particular, the escape of particles from SNRs may be more complex than generally assumed.

Petrosian, Vahé; Chen, Qingrong

2014-05-01

78

Comer Schools: Are They Recognizable through Direct Observation?  

ERIC Educational Resources Information Center

The Comer School Development Program is a reform model aimed at creating a positive school climate. Research has confirmed that specific Comer characteristics, such as an orderly, well-maintained facility, classroom diversity, and staff friendliness, can be observed. This study uses the Comer Visitor Observation instrument to determine whether…

Aguilera, Linda; Crane, Patti; Hamer, Mariann; Morrison, Melissa; Serrano, Dina

79

Towards an Optimal Observation Strategy for Direct Detection Exoplanet Searches  

Microsoft Academic Search

This paper presents a look at ongoing investigations into the strategies needed to characterize the orbits of observed exoplanets in an optimal manner. Also introduced is an efficient manner of the selection of possible orbits consistent with the observation of an exoplanet. Specifically, this work looks at the ability to conclude that a planet's orbit is resident in the habitable

Jonathan W. Arenberg; Todd E. Schuman

2006-01-01

80

Direct Observation of Steady-state Microtubule Dynamics  

Microsoft Academic Search

Different types of unusual dynamic behav- ior have been reported for steady-state microtubules. While almost all earlier reports relied on kinetic mea- surements of bulk polymerization, we have directly visualized the steady-state addition of subunits to indi- vidual microtubules through the use of tubulin derivi- tized with biotin. Biotinylated tubulin was used both as an internal \\

David Kristofferson; Tim Mitchison; Marc Kirschner

2006-01-01

81

Retinex Image Processing: Improved Fidelity To Direct Visual Observation  

Microsoft Academic Search

Recorded color images differ from direct human viewing by the lack of dynamic range compression and color constancy. Research is summarized which develops the center\\/surround retinex concept originated by Edwin Land through a single- scale design to a multi-scale design with color restoration (MSRCR). The MSRCR synthesizes dynamic range compression, color constancy, and color rendition and, thereby, approaches fidelity to

Daniel J. Jobson; Zia-ur Rahman; Glenn A. Woodell

1996-01-01

82

Simultaneous Measurements of direct, semi-direct and indirect aerosol forcing with Stacked Autonomous UAVs: A New Observing Platform  

Microsoft Academic Search

We report here first time demonstration with three autonomously flying Unmanned Aerial Vehicles (UAVs) of cloudy sky albedo, transmission atmospheric solar absorption, aerosol and cloud droplet concentrations and number densities. From these direct measurements we derive the direct, semi-direct and the first indirect aerosol forcing. The observing system consisted of 3 light weight UAVs, instrumented with miniaturized instruments (Roberts et

V. Ramanathan; G. Roberts; M. V. Ramana; C. Corrigan; H. Nguyen

2006-01-01

83

Direct observation of defect structure in protein crystals by atomic force and transmission electron microscopy  

SciTech Connect

We have examined the structure of S-layers isolated from {ital Sulfolobus} {ital acidocaldarius} using atomic force microscopy (AFM) and transmission electron microscopy (TEM). From the AFM images, we were able to directly observe individual dimers of the crystal, defects in the crystal structure, and twin boundaries. We have identified two types of boundaries, one defined by a mirror plane and the other by a glide plane. This work shows that twin boundaries are highly structured regions that are directly related to the organization of units within each crystal domain. Projection maps from TEM images have shown that there are significant differences in the final average maps, depending on which side of the sample is adsorbed to the carbon support film. Comparison of AFM images to TEM projection maps has allowed us to relate high magnification views obtained by AFM to the relatively high resolution information obtained by electron microscopy and image processing.

Devaud, G. (Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States)); Furcinitti, P.S. (Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309 (United States)); Fleming, J.C.; Lyon, M.K.; Douglas, K. (Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States))

1992-09-01

84

Direct observation of defect structure in protein crystals by atomic force and transmission electron microscopy.  

PubMed

We have examined the structure of S-layers isolated from Sulfolobus acidocaldarius using atomic force microscopy (AFM) and transmission electron microscopy (TEM). From the AFM images, we were able to directly observe individual dimers of the crystal, defects in the crystal structure, and twin boundaries. We have identified two types of boundaries, one defined by a mirror plane and the other by a glide plane. This work shows that twin boundaries are highly structured regions that are directly related to the organization of units within each crystal domain. Projection maps from TEM images have shown that there are significant differences in the final average maps has allowed us to relate high magnification views obtained by AFM to the relatively high resolution information obtained by electron microscopy and image processing. PMID:1420904

Devaud, G; Furcinitti, P S; Fleming, J C; Lyon, M K; Douglas, K

1992-09-01

85

Direct Observation of IBW Induced Poloidal Flow in TFTR  

SciTech Connect

Shearing of the plasma poloidal rotation velocity was observed during application of ion Bernstein wave IBW) power in the Tokamak Fusion Test Reactor (TFTR) tokamak. The first evidence of corroboration between measured poloidal velocity shearing and actively induced Reynolds stress effects is presented. A model reproduces salient experimental features: The observed sheared flow occurs near the tritium fifth harmonic cyclotron resonance layer and depends strongly on the tritium density, in agreement with the model. Furthermore, the model reproduces the observed insensitivity of the induced rotation to the tritium density in the region between the third deuterium harmonic layer and the fifth tritium harmonic layer.

Bell, R.E.; Bernabei, S.; Hosca, J.C.; LeBlanc, B.P.; Majeski, R.; et al.

1998-11-01

86

Physical Activity Surveillance in Parks Using Direct Observation  

PubMed Central

Introduction Primary features of observational public health surveillance instruments are that they are valid, can reliably estimate physical activity behaviors, and are useful across diverse geographic settings and seasons by different users. Previous studies have reported the validity and reliability of Systematic Observation of Play and Recreation in Communities (SOPARC) to estimate park and user characteristics. The purpose of this investigation was to establish the use of SOPARC as a surveillance instrument and to situate the findings from the study in the context of the previous literature. Methods We collected data by using SOPARC for more than 3 years in 4 locations: Philadelphia, Pennsylvania; Columbus, Ohio; Chapel Hill/Durham, North Carolina; and Albuquerque, New Mexico during spring, summer, and autumn. Results We observed a total of 35,990 park users with an overall observer reliability of 94% (range, 85%–99%) conducted on 15% of the observations. We monitored the proportion of park users engaging in moderate-to-vigorous physical activity (MVPA) and found marginal differences in MVPA by both city and season. Park users visited parks significantly more on weekend days than weekdays and visitation rates tended to be lower during summer than spring. Conclusion SOPARC is a highly reliable observation instrument that can be used to collect data across diverse geographic settings and seasons by different users and has potential as a surveillance system.

McKenzie, Thomas L.; Cohen, Deborah; Evenson, Kelly R.; Golinelli, Daniela; Hillier, Amy; Lapham, Sandra C.; Williamson, Stephanie

2014-01-01

87

Direct observation of playgroup therapy for social skills deficits  

Microsoft Academic Search

This study assesses the impact of play-group therapy on five 5-year-old boys suffering from relation difficulties within their peer groups. Twelve non-directive therapy sessions were conducted by two therapists, and were based on proven models of operant conditioning, modeling and coaching. A comparison of pre-and post-therapy assessments showed a significant improvement in social skills and in behavior overall. Further prospective

Michel D. Boulanger; Catherine Langevin

1992-01-01

88

Directly Observed Membrane Fusion Between Oppositely Charged Phospholipid Bilayers  

Microsoft Academic Search

.   A novel method was developed for the direct examination of pairwise encounters between positively and negatively charged\\u000a phospholipid bilayer vesicles. Giant bilayer vesicles (unilamellar, 4–20 ?m in diameter) prepared from 1,2-dioleoyl-sn-glycero-3-ethylphosphocholine, a new cationic phospholipid derivative, were electrophoretically maneuvered into contact with\\u000a individual anionic phospholipid vesicles. Fluorescence video microscopy revealed that such vesicles commonly underwent fusion\\u000a within milliseconds (1

D. P. Pantazatos; R. C. MacDonald

1999-01-01

89

Van Allen Probes observations of direct wave-particle interactions  

NASA Astrophysics Data System (ADS)

increases, or "bursts," of 17-26 keV electron fluxes in conjunction with chorus wave bursts were observed following a plasma injection on 13 January 2013. The pitch angle distributions changed during the burst events, evolving from sinN(?) to distributions that formed maxima at ? = 75-80°, while fluxes at 90° and <60° remained nearly unchanged. The observations occurred outside of the plasmasphere in the postmidnight region and were observed by both Van Allen Probes. Density, cyclotron frequency, and pitch angle of the peak flux were used to estimate resonant electron energy. The result of ~15-35 keV is consistent with the energies of the electrons showing the flux enhancements and corresponds to electrons in and above the steep flux gradient that signals the presence of an Alfvén boundary in the plasma. The cause of the quasiperiodic nature (on the order of a few minutes) of the bursts is not understood at this time.

Fennell, J. F.; Roeder, J. L.; Kurth, W. S.; Henderson, M. G.; Larsen, B. A.; Hospodarsky, G.; Wygant, J. R.; Claudepierre, J. S. G.; Blake, J. B.; Spence, H. E.; Clemmons, J. H.; Funsten, H. O.; Kletzing, C. A.; Reeves, G. D.

2014-03-01

90

Future directions in X-ray/gamma-ray observations  

NASA Technical Reports Server (NTRS)

Facilities available for X ray and gamma ray astronomical observations in the late 1980s are described, with an emphasis on NASA programs. Current European programs for launching Rosat and Exosat will provide coverage in the 0.4-60 keV energy range. The proposed NASA advanced X ray astrophysics facility is intended to cover the 0.1-8 keV range with higher than 0.5 arcsec resolution. The Japanese Astro-B, scheduled for launch in 1983, observes in the 1-60 keV range. X ray and gamma ray observations are also scheduled for Spacelab flights. The French-Soviet Gamma-1 spark chamber high energy gamma ray telescope is intended for LEO orbit and observations in the energy range above 50 MeV with a 2 deg, 1-5 arcmin resolution. The NASA gamma ray observatory is set for 1988 launch and will feature four instruments to monitor the 60 keV-300 GeV range. Balloon-borne instrumentation will also be launched, with attention given to the medium gamma ray energy range from 1-30 MeV.

Kniffen, D. A.

1982-01-01

91

Direct observation of warping in the plasma sheet of Saturn  

NASA Astrophysics Data System (ADS)

The ENA images from the Ion Neutral CAmera (INCA) on the Cassini spacecraft are projected onto the noon-midnight plane of Sun-Saturn orbital coordinates, and a composite ``image'' of Saturn's plasma sheet is constructed from dawn-side observations of 20-50 keV hydrogens obtained from days 352 to 361 in 2004. The maxima in the intensity contours define the center of the plasma sheet in the noon-midnight plane. This plasma sheet surface displays a distinct bending or ``warping'' above Saturn's equatorial plane at radial distances of beyond ~15 RS on the nightside. On the dayside, the plasma sheet lies close to the equator all the way to the magnetopause. The observed warping agrees with the ``bowl'' model derived from measurements of Saturn's magnetic field, but fits more closely a simple third-order polynomial.

Carbary, J. F.; Mitchell, D. G.; Paranicas, C.; Roelof, E. C.; Krimigis, S. M.

2008-12-01

92

Direct observation of misfit dislocation glide on surfaces.  

PubMed

Using scanning tunneling microscopy we have observed thermally induced dislocation glide in monolayer Cu films on Ru(0001) at room temperature. The motion is governed by a Peierls barrier that depends on the detailed structure of the dislocations, in particular upon whether the threading dislocations that terminate them are dissociated or not. Calculations based on the Frenkel-Kontorova model reproduce the threading dislocation structure and provide estimates of the Peierls barrier and dislocation stiffness which are consistent with experiment. PMID:11329332

de La Figuera, J; Pohl, K; de La Fuente, O R; Schmid, A K; Bartelt, N C; Carter, C B; Hwang, R Q

2001-04-23

93

Bottom Velocity Observations Directly under the Gulf Stream.  

PubMed

Speeds as high as 44 centimeters per second were observed 200 meters above the ocean bottom under the Gulf Stream at 70 degrees W longitude and were associated with time-dependent motion that had a speed range of 40 centimeters per second and a time scale of about 30 days. These deep current fluctuations appear to be coupled with fluctuations in the surface position of the Stream and with surface and bottom current fluctuations 200 kilometers to the north. PMID:17744049

Schmitz, W J; Robinson, A R; Fuglister, F C

1970-12-11

94

Direct Observation of Misfit Dislocation Glide on Surfaces  

SciTech Connect

Using scanning tunneling microscopy we have observed thermally induced dislocation glide in monolayer Cu films on Ru(0001) at room temperature. The motion is governed by a Peierls barrier that depends on the detailed structure of the dislocations, in particular upon whether the threading dislocations that terminate them are dissociated or not. Calculations based on the Frenkel-Kontorova model reproduce the threading dislocation structure and provide estimates of the Peierls barrier and dislocation stiffness which are consistent with experiment.

de la Figuera, J.; Pohl, K.; de la Fuente, O. Rodriguez; Schmid, A. K.; Bartelt, N. C.; Carter, C. B.; Hwang, R. Q.

2001-04-23

95

Direct Observation of Misfit Dislocation Glide on Surfaces  

NASA Astrophysics Data System (ADS)

Using scanning tunneling microscopy we have observed thermally induced dislocation glide in monolayer Cu films on Ru(0001) at room temperature. The motion is governed by a Peierls barrier that depends on the detailed structure of the dislocations, in particular upon whether the threading dislocations that terminate them are dissociated or not. Calculations based on the Frenkel-Kontorova model reproduce the threading dislocation structure and provide estimates of the Peierls barrier and dislocation stiffness which are consistent with experiment.

de La Figuera, J.; Pohl, K.; de La Fuente, O. Rodríguez; Schmid, A. K.; Bartelt, N. C.; Carter, C. B.; Hwang, R. Q.

2001-04-01

96

Direct observation of hydrides formation in cavity-grade niobium  

NASA Astrophysics Data System (ADS)

Niobium is an important technological superconductor used to make radio frequency cavities for particle accelerators. Using laser confocal microscopy we have directly investigated hydride precipitates formation in cavity-grade niobium at 77 and 140 K. We have found that large hydrides were usually formed after chemical or mechanical treatments, which are known to lead to a strong degradation of the quality factor known as Q disease. From our experiments we can conclude that hydrides causing Q disease are islands with a characteristic thickness of ?100nm and in-plane dimensions 1-10?m. Our results show that mechanical polishing uploads a lot of hydrogen into bulk niobium while electropolishing leads to a mild contamination. Vacuum treatments at 600-800°C are demonstrated to preclude large hydride formation in line with the absence of Q disease in similarly treated cavities.

Barkov, F.; Romanenko, A.; Grassellino, A.

2012-12-01

97

Direct observation of tetrahedrally coordinated Fe(III) in ferrihydrite.  

PubMed

Ferrihydrite is a common iron hydroxide nanomineral commonly found in soils, sediments, and surface waters. Reactivity with this important environmental surface often controls the fate and mobility of both essential nutrients and inorganic contaminants. Despite the critical role of ferrihydrite in environmental geochemistry, its structure is still debated. In this work, we apply bulk sensitive Fe L edge X-ray absorption spectroscopy to study the crystal field environment of the Fe in ferrihydrite and other Fe oxides of known structure. This direct probe of the local electronic structure provides verification of the presence of tetrahedrally coordinated Fe(III) in the structure of ferrihydrite and puts to rest the controversy on this issue. PMID:22369094

Peak, Derek; Regier, Tom

2012-03-20

98

Direct observation of internal energy distributions of C5-  

NASA Astrophysics Data System (ADS)

Photon induced decay of C5- has been measured in an electrostatic storage ring. The time dependence of the photo-enhanced decay is close to a 1/t decay which indicates a thermal process. The deviation from the expected power of -1 is quantitatively explained by the small heat capacity of the anion. Measurements of the photo-enhanced decay at different storage times and photon energies allow a determination of the radiative cooling rate and the energy distribution of the ions. The average energy content between 15 and 70 ms is found to vary as time to the power -0.72, and at 50 ms the ions contain an average excitation energy of 0.5 eV. The time dependent energy distribution is consistent with cooling by infrared photon emission if published oscillator strengths are reduced by a factor 2.5, in contrast to cooling of larger molecular carbon-based ions where electronic transitions cause a much stronger cooling.

Goto, M.; Sundén, A. E. K.; Shiromaru, H.; Matsumoto, J.; Tanuma, H.; Azuma, T.; Hansen, K.

2013-08-01

99

Direct observation of muon pair production by cosmic ray muons  

NASA Astrophysics Data System (ADS)

Experimental data collected in a long-term exposition of the big liquid-argon spectrometer BARS in horizontal cosmic ray flux have been analysed to select the events corresponding to muon pair production by muons in the inner fiducial volume of the detector. The observed number of such events (7 among 1.9 million muons passing through the setup) is in agreement with recent theoretical calculations of the cross section but is about 7 times lower than the prediction obtained with the cross section formula widely used earlier for various estimations.

Anikeev, V. B.; Denisov, S. P.; Gurzhiev, S. N.; Kelner, S. R.; Kirina, T. M.; Kokoulin, R. P.; Lipaev, V. V.; Petrukhin, A. A.; Rybin, A. M.; Sergiampietri, F.; Yanson, E. E.; Zolina, O. S.

100

Direct observation of spiropyran phosphorescence in imidazolium ionic liquids  

NASA Astrophysics Data System (ADS)

Emission spectroscopy is used to investigate the photochromism of a spiropyran ester in imidazolium ionic liquids. While the spiropyran exhibits positive photochromism, the ring-opening reaction is slowed such that both fluorescence from the merocyanine form and phosphorescence from the spiro form are observed. These results illustrate the first example of spiropyran phosphorescence in ionic liquids and suggest that this system could be used to design a robust two-color emitting molecular device that depends on the state of the photochrome, where the state can be modulated by internal (the medium) and external (irradiation wavelength) factors.

Naughton, Sean P.; Gaudet, Robyn M.; Leslie, Anne A.; Keirstead, Amy E.

2013-01-01

101

Direct observation of steady-state microtubule dynamics  

PubMed Central

Different types of unusual dynamic behavior have been reported for steady-state microtubules. While almost all earlier reports relied on kinetic measurements of bulk polymerization, we have directly visualized the steady-state addition of subunits to individual microtubules through the use of tubulin derivitized with biotin. Biotinylated tubulin was used both as an internal "seed" for polymerization and as a marker for assembly onto the ends of microtubules composed of purified tubulin. Biotinylated segments were distinguished from unmodified tubulin by double-label immunofluorescence. Microtubule lengths, number concentrations, and segment lengths have been monitored with time at steady state under two buffer conditions. The results indicate that the microtubule steady state under these conditions is a balance between a majority of slowly growing microtubules and a minority of rapidly depolymerizing ones as described by the "dynamic instability" model (Mitchison T., and M. Kirschner, 1984, Nature (Lond.)., 312:232-242). Microtubules show no evidence of treadmilling; instead most show progressive growth off both ends at steady state. Although solvent conditions markedly influence the growth rates, qualitatively the behavior is unchanged.

1986-01-01

102

New Directions in the NOAO Observing Proposal System  

NASA Astrophysics Data System (ADS)

For the past eight years NOAO has been refining its on-line observing proposal system. Virtually all related processes are now handled electronically. Members of the astronomical community can submit proposals through email, web form, or via the Gemini Phase I Tool. NOAO staff can use the system to do administrative tasks, scheduling, and compilation of various statistics. In addition, all information relevant to the TAC process is made available on-line, including the proposals themselves (in HTML, PDF and PostScript) and technical comments. Grades and TAC comments are entered and edited through web forms, and can be sorted and filtered according to specified criteria. Current developments include a move away from proprietary solutions, toward open standards such as SQL (in the form of the MySQL relational database system), Perl, PHP and XML.

Gasson, David; Bell, Dave

103

Direct observation of lightning-produced NOx: A clouded view  

NASA Astrophysics Data System (ADS)

Lightning is an important source of NOx in the free troposphere, especially in the tropics, with high impact on ozone production. However, estimates of lightning NOx (LNOx) per flash are still quite uncertain. Here we discuss the potential of satellite observations of NO2 to quantify freshly produced LNOx, with a focus on strong lightning events. Recent cloud-resolving model studies reveal that satellite measurements are sensitive for freshly produced LNOx, even under cumulonimbus cloud conditions. Also, some case studies show clearly enhanced NO2 column densities over active lightning systems. We present a systematic analysis of NO2 tropospheric slant column densities (TSCDs) from satellite measurements over active thunderstorms, as detected by the World-Wide Lightning Location Network (WWLLN), where WWLLN detection efficiency is estimated using the LIS flash climatology. Only very strong lightning events are considered, having flash densities (FDs) above 1 km-2 h-1 inside the satellite pixel within the last hour. The respective NO2 TSCDs are expected to be higher than 7.5e15 molec/cm2 (as long as outflow can be neglected), which should be clearly visible in the satellite measurements. We find about 100 satellite measurements per year coinciding with high flash rates. For some of these events, a clear enhancement of NO2 TSCD could be observed. However, the measured TSCDs are generally far below the expected values. In addition, in most of the cases, no significantly enhanced NO2 TSCDs could be found, and the correlation of FD and TSCD is low. Our study reveals fundamental inconsistencies of recent estimates of the LNOx production per flash combined with the sensitivity of LNOx from satellite. Further investigation has to reveal how far this can be related to the assumed LNOx production per flash, radiative transfer issues, and/or NOx chemistry in cumulonimbus clouds.

Beirle, Steffen; Wagner, Thomas

2010-05-01

104

Direct Observation of Long-Lived Isomers in Bi212  

NASA Astrophysics Data System (ADS)

Long-lived isomers in Bi212 have been studied following U238 projectile fragmentation at 670 MeV per nucleon. The fragmentation products were injected as highly charged ions into a storage ring, giving access to masses and half-lives. While the excitation energy of the first isomer of Bi212 was confirmed, the second isomer was observed at 1478(30) keV, in contrast to the previously accepted value of >1910keV. It was also found to have an extended Lorentz-corrected in-ring half-life >30min, compared to 7.0(3) min for the neutral atom. Both the energy and half-life differences can be understood as being due a substantial, though previously unrecognized, internal decay branch for neutral atoms. Earlier shell-model calculations are now found to give good agreement with the isomer excitation energy. Furthermore, these and new calculations predict the existence of states at slightly higher energy that could facilitate isomer deexcitation studies.

Chen, L.; Walker, P. M.; Geissel, H.; Litvinov, Yu. A.; Beckert, K.; Beller, P.; Bosch, F.; Boutin, D.; Caceres, L.; Carroll, J. J.; Cullen, D. M.; Cullen, I. J.; Franzke, B.; Gerl, J.; Górska, M.; Jones, G. A.; Kishada, A.; Knöbel, R.; Kozhuharov, C.; Kurcewicz, J.; Litvinov, S. A.; Liu, Z.; Mandal, S.; Montes, F.; Münzenberg, G.; Nolden, F.; Ohtsubo, T.; Patyk, Z.; Plaß, W. R.; Podolyák, Zs.; Rigby, S.; Saito, N.; Saito, T.; Scheidenberger, C.; Simpson, E. C.; Shindo, M.; Steck, M.; Sun, B.; Williams, S. J.; Weick, H.; Winkler, M.; Wollersheim, H.-J.; Yamaguchi, T.

2013-03-01

105

Relation between Direct Observation of Relaxation and Self-Reported Mindfulness and Relaxation States  

ERIC Educational Resources Information Center

Forty-four individuals, 18-47 (MN 21.8, SD 5.63) years of age, took part in a study examining the magnitude and direction of the relationship between self-report and direct observation measures of relaxation and mindfulness. The Behavioral Relaxation Scale (BRS), a valid direct observation measure of relaxation, was used to assess relaxed behavior…

Hites, Lacey S.; Lundervold, Duane A.

2013-01-01

106

Direct in situ observation of nanoparticle synthesis in a liquid crystal surfactant template.  

PubMed

Controlled and reproducible synthesis of tailored materials is essential in many fields of nanoscience. In order to control synthesis, there must be a fundamental understanding of nanostructure evolution on the length scale of its features. Growth mechanisms are usually inferred from methods such as (scanning) transmission electron microscopy ((S)TEM), where nanostructures are characterized after growth is complete. Such post mortem analysis techniques cannot provide the information essential to optimize the synthesis process, because they cannot measure nanostructure development as it proceeds in real time. This is especially true in the complex rheological fluids used in preparation of nanoporous materials. Here we show direct in situ observations of synthesis in a highly viscous lyotropic liquid crystal template on the nanoscale using a fluid stage in the STEM. The nanoparticles nucleate and grow to ?5 nm particles, at which point growth continues through the formation of connections with other nanoparticles around the micelles to form clusters. Upon reaching a critical size (>10-15 nm), the clusters become highly mobile in the template, displacing and trapping micelles within the growing structure to form spherical, porous nanoparticles. The final products match those synthesized in the lab ex situ. This ability to directly observe synthesis on the nanoscale in rheological fluids, such as concentrated aqueous surfactants, provides an unprecedented understanding of the fundamental steps of nanomaterial synthesis. This in turn allows for the synthesis of next-generation materials that can strongly impact important technologies such as organic photovoltaics, energy storage devices, catalysis, and biomedical devices. PMID:22439964

Parent, Lucas R; Robinson, David B; Woehl, Taylor J; Ristenpart, William D; Evans, James E; Browning, Nigel D; Arslan, Ilke

2012-04-24

107

Linear pharmacokinetic equations allowing direct calculation of many needed pharmacokinetic parameters from the coefficients and exponents of polyexponential equations which have been fitted to the data  

Microsoft Academic Search

It is shown that if the numerical values of the coefficients and exponents of the polyexponential equation describing the whole blood (plasma or serum) concentration after administration of a drug by bolus intravenous injection, or during or after termination of a constantrate intravenous infusion, are known, then many needed pharmacokinetic parameters may be obtained directly. Parameters readily calculated by simple

John G. Wagner

1976-01-01

108

Measuring Implementation of the Direct Instruction Model in an Urban School District: An Observational Approach.  

ERIC Educational Resources Information Center

During an extensive inservice program, teachers and aides in 20 kindergarten and first grade Follow Through Classrooms were observed for mastery of the Direct Instruction Model. Two trained observers used the Direct Instruction Supervisor Code to record behavior in the fall, winter, and spring. Subjects were observed while teaching a 12 minute…

Gersten, Russell M.; Carnine, Doug

109

Quality assessment in nursing homes by systematic direct observation: feeding assistance.  

PubMed

Background. Direct observation of care is an important data source for nursing home (NH) quality assessment, especially in light of evidence that chart information is inaccurate or incomplete for many daily care areas. The purpose of this study was to describe a standardized feeding assistance observational protocol that is designed for routine use by external (survey teams) and internal (licensed NH staff) quality assurance personnel to (i) maximize the amount of useful information gained from relatively brief observational periods; (ii) provide specific rules of measurement, which allow for replication and valid comparisons between NHs; and (iii) provide specific scoring rules that allow defensible categorical statements to be made about feeding assistance care quality within the NH. Methods. Four feeding assistance care quality indicators (QIs) were defined and operationalized in this study for 302 long-term residents in 10 skilled NHs: (i) Staff ability to accurately identify residents with clinically significant low oral food and fluid intake during mealtime; (ii) Staff ability to provide feeding assistance to at-risk residents during mealtime; (iii) Staff ability to provide feeding assistance to residents identified by the Minimum Data Set as requiring staff assistance to eat; and (iv) Staff ability to provide a verbal prompt to residents who receive physical assistance at mealtimes. Results. There were significant differences between facilities for three of the four QIs. The proportion of participants in each facility where staff "failed" the QIs ranged as follows: (Quality Indicator i) 42% to 91%; (ii) 25% to 73%; (iii) 11% to 82%; and (iv) 0% to 100%. Conclusions. A standardized observational protocol can be used to accurately measure the quality of feeding assistance care in NHs. This protocol is replicable and shows significant differences between facilities with respect to accuracy of oral intake documentation and the adequacy and quality of feeding assistance during mealtimes. PMID:12242322

Simmons, Sandra F; Babineau, Sarah; Garcia, Emily; Schnelle, John F

2002-10-01

110

Direct real time observation of base flipping by the EcoRI DNA methyltransferase.  

PubMed

DNA methyltransferases are excellent prototypes for investigating DNA distortion and enzyme specificity because catalysis requires the extrahelical stabilization of the target base within the enzyme active site. The energetics and kinetics of base flipping by the EcoRI DNA methyltransferase were investigated by two methods. First, equilibrium dissociation constants (KDDNA) were determined for the binding of the methyltransferase to DNA containing abasic sites or base analogs incorporated at the target base. Consistent with a base flipping mechanism, tighter binding to oligonucleotides containing destabilized target base pairs was observed. Second, total intensity stopped flow fluorescence measurements of DNA containing 2-aminopurine allowed presteady-state real time observation of the base flipping transition. Following the rapid formation of an enzyme-DNA collision complex, a biphasic increase in total intensity was observed. The fast phase dominated the total intensity increase with a rate nearly identical to k(methylation) determined by rapid chemical quench-flow techniques (Reich, N. O., and Mashoon, N. (1993) J. Biol. Chem. 268, 9191-9193). The restacking of the extrahelical base also revealed biphasic kinetics with the recovered amplitudes from these off-rate experiments matching very closely to those observed during the base unstacking process. These results provide the first direct and continuous observation of base flipping and show that at least two distinct conformational transitions occurred at the flipped base subsequent to complex formation. Furthermore, our results suggest that the commitment to catalysis during the methylation of the target site is not determined at the level of the chemistry step but rather is mediated by prior intramolecular isomerization within the enzyme-DNA complex. PMID:9442083

Allan, B W; Beechem, J M; Lindstrom, W M; Reich, N O

1998-01-23

111

Direct Imaging of an Emerging Flux Rope and a Resulting Chromospheric Jet Observed by Hinode  

NASA Astrophysics Data System (ADS)

Magnetic flux emergence has been traditionally observed on the disk by identifying changes in magnetograms. Observations near the limb offer an alternative perspective and allow direct imaging of emerging flux ropes. We present Hinode/SOT Ca II H observations of such an event in an equatorial coronal hole on 2007 February 9. The precursor of the event was a bundle of fine material threads that extended at an oblique angle above the chromosphere and appeared to rotate about a common axis. This bundle first slowly and then rapidly swung up, accompanied by a loop that appeared at the base of the bundle and expanded at comparable rates. During the first (slow rise) stage, the apex of the loop ascended at 16 km/s, a velocity similar to that of H-alpha arch filaments (e.g., Chou & Zirin) and of emerging flux ropes expanding into the corona as found in MHD simulations (e.g., Fan & Gibson; Martinez-Sykora). The second stage started at the onset of a GOES A5 flare and the loop expansion accelerated, reaching a velocity of 130 km/s when the loop appeared to rupture near the peak of the flare. The material bundle then swung back in a whiplike manner and developed into a collimated jet, exhibiting oscillatory transverse motions across its axis, as expected from unwinding twists. Some jet material fell back along smooth streamlines, which bypass an unseen dome and presumably a null point in the low corona, depicting an inverted-Y shape. Some of these observations resemble the model (e.g., Uchida & Shibata) of the emergence of a twisted flux rope into an open field region that leads to reconnection and formation of a jet. Some observations are, however, not predicted in previous models and we will discuss their implications.

Liu, Wei; Berger, T.; Title, A. M.; Tarbell, T. D.; DeRosa, M.

2010-05-01

112

Capturing intraoperative process deviations using a direct observational approach: the glitch method  

PubMed Central

Objectives To develop a sensitive, reliable tool for enumerating and evaluating technical process imperfections during surgical operations. Design Prospective cohort study with direct observation. Setting Operating theatres on five sites in three National Health Service Trusts. Participants Staff taking part in elective and emergency surgical procedures in orthopaedics, trauma, vascular and plastic surgery; including anaesthetists, surgeons, nurses and operating department practitioners. Outcome measures Reliability and validity of the glitch count method; frequency, type, temporal pattern and rate of glitches in relation to site and surgical specialty. Results The glitch count has construct and face validity, and category agreement between observers is good (?=0.7). Redundancy between pairs of observers significantly improves the sensitivity over a single observation. In total, 429 operations were observed and 5742 glitches were recorded (mean 14 per operation, range 0–83). Specialty-specific glitch rates varied from 6.9 to 8.3/h of operating (ns). The distribution of glitch categories was strikingly similar across specialties, with distractions the commonest type in all cases. The difference in glitch rate between specialty teams operating at different sites was larger than that between specialties (range 6.3–10.5/h, p<0.001). Forty per cent of glitches occurred in the first quarter of an operation, and only 10% occurred in the final quarter. Conclusions The glitch method allows collection of a rich dataset suitable for analysing the changes following interventions to improve process safety, and appears reliable and sensitive. Glitches occur more frequently in the early stages of an operation. Hospital environment, culture and work systems may influence the operative process more strongly than the specialty.

Morgan, Lauren; Robertson, Eleanor; Hadi, Mohammed; Catchpole, Ken; Pickering, Sharon; New, Steve; Collins, Gary; McCulloch, Peter

2013-01-01

113

Direct Observation of Active Protein Folding Using Lock-in Force Spectroscopy  

PubMed Central

Direct observation of the folding of a single polypeptide chain can provide important information about the thermodynamic states populated along its folding pathway. In this study, we present a lock-in force-spectroscopy technique that improves resolution of atomic-force microscopy force spectroscopy to 400 fN. Using this technique we show that immunoglobulin domain 4 from Dictyostelium discoideum filamin (ddFLN4) refolds against forces of ?4 pN. Our data show folding of this domain proceeds directly from an extended state and no thermodynamically distinct collapsed state of the polypeptide before folding is populated. Folding of ddFLN4 under load proceeds via an intermediate state. Three-state folding allows ddFLN4 to fold against significantly larger forces than would be possible for a mere two-state folder. We present a general model for protein folding kinetics under load that can predict refolding forces based on chain-length and zero force refolding rate.

Schlierf, Michael; Berkemeier, Felix; Rief, Matthias

2007-01-01

114

Guiding attention to specific locations by combining symbolic information about direction and distance: are human observers direction experts?  

PubMed

Spatial symbols can guide attention to a specific location only when they convey information about both direction and distance. However, the spatial symbols that have been used in previous cuing studies only convey information about direction, but not distance. Consequently, previous studies have only demonstrated that spatial symbols can exert partial control over the guidance of attention to specific locations. The present study investigated whether spatial symbols can also exert a more complete form of control over the guidance of attention to specific locations by presenting symbolic cues that conveyed information about both direction and distance. The effects of each spatial dimension were isolated by varying the spatial validity of each dimension separately. Consistent with the notion of more complete control, the results of 4 experiments showed that observers routinely combined symbolic information about direction and distance to guide their attention to specific locations. Perhaps more importantly, the results also suggested that observers demonstrated greater expertise orienting in response to direction symbols, though this expertise was only observed when these symbols were both familiar and commonly used to orient attention in the outside world. These results extend current theories, and set a new standard for studying symbolic control. PMID:24245500

Gibson, Bradley S; Sztybel, Pedro

2014-04-01

115

Mid-depth recirculation observed in the interior Labrador and Irminger seas by direct velocity measurements  

PubMed

The Labrador Sea is one of the sites where convection exports surface water to the deep ocean in winter as part of the thermohaline circulation. Labrador Sea water is characteristically cold and fresh, and it can be traced at intermediate depths (500-2,000 m) across the North Atlantic Ocean, to the south and to the east of the Labrador Sea. Widespread observations of the ocean currents that lead to this distribution of Labrador Sea water have, however, been difficult and therefore scarce. We have used more than 200 subsurface floats to measure directly basin-wide horizontal velocities at various depths in the Labrador and Irminger seas. We observe unanticipated recirculations of the mid-depth (approximately 700 m) cyclonic boundary currents in both basins, leading to an anticyclonic flow in the interior of the Labrador basin. About 40% of the floats from the region of deep convection left the basin within one year and were rapidly transported in the anticyclonic flow to the Irminger basin, and also eastwards into the subpolar gyre. Surprisingly, the float tracks did not clearly depict the deep western boundary current, which is the expected main pathway of Labrador Sea water in the thermohaline circulation. Rather, the flow along the boundary near Flemish Cap is dominated by eddies that transport water offshore. Our detailed observations of the velocity structure with a high data coverage suggest that we may have to revise our picture of the formation and spreading of Labrador Sea water, and future studies with similar instrumentation will allow new insights on the intermediate depth ocean circulation. PMID:10993072

Lavender; Davis; Owens

2000-09-01

116

Wide-field direct CCD observations supporting the Astro-1 Space Shuttle mission's Ultraviolet Imaging Telescope  

NASA Technical Reports Server (NTRS)

Wide field direct CCD observations are being obtained to support and complement the vacuum-ultraviolet (VUV) images provided by Astro's Ultraviolet Imaging Telescope (UIT) during a Space Shuttle flight in December 1990. Because of the wide variety of projects addressed by UIT, the fields observed include (1) galactic supernova remnants such as the Cygnus Loop and globular clusters such as Omega Cen and M79; (2) the Magellanic Clouds, M33, M81, and other galaxies in the Local Group; and (3) rich clusters of galaxies, principally the Perseus cluster and Abell 1367. Ground-based observations have been obtained for virtually all of the Astro-1 UIT fields. The optical images allow identification of individual UV sources in each field and provide the long baseline in wavelength necessary for accurate analysis of UV-bright sources. To facilitate use of our optical images for analysis of UIT data and other projects, we plan to archive them, with the UIT images, at the National Space Science Data Center (NSSDC), where they will be universally accessible via anonymous FTP. The UIT, one of three telescopes comprising the Astro spacecraft, is a 38-cm f/9 Ritchey-Chretien telescope on which high quantum efficiency, solar-blind image tubes are used to record VUV images on photographic film. Five filters with passbands centered between 1250A and 2500A provide both VUV colors and a measurement of extinction via the 2200A dust feature. The resulting calibrated VUV pictures are 40 arcminutes in diameter at 2.5 arcseconds resolution. The capabilities of UIT, therefore, complement HST's WFPC: the latter has 40 times greater collecting area, while UIT's usable field has 170 times WFPC's field area.

Hintzen, Paul; Angione, Ron; Talbert, Freddie; Cheng, K.-P.; Smith, Eric; Stecher, Theodore P.

1993-01-01

117

Observation of Direction and Speed at Tsushima Current by Shipboard ADCP  

NASA Astrophysics Data System (ADS)

Tsushima Warm Current is running at Japan Sea form South to North. We observed its current direction and speed at the north region of Noto peninsula by the shipboard ADCP. The observations were acted at two times, which are summer season of 2004 and 2005. From these observations, the main flows of the currents are steady, which directions are almost along to the coast and the speeds are almost 50-80cm/s. Also, at the shadow area of the peninsula for the main flow, the disturbed flows are observed.

Chiba, Hajime; Furuyama, Shoichi; Yokoi, Koji

118

Does prey size matter? Novel observations of feeding in the leatherback turtle (Dermochelys coriacea) allow a test of predator-prey size relationships.  

PubMed

Optimal foraging models predict that large predators should concentrate on large prey in order to maximize their net gain of energy intake. Here, we show that the largest species of sea turtle, Dermochelys coriacea, does not strictly adhere to this general pattern. Field observations combined with a theoretical model suggest that a 300 kg leatherback turtle would meet its energetic requirements by feeding for 3-4 h a day on 4 g jellyfish, but only if prey were aggregated in high-density patches. Therefore, prey abundance rather than prey size may, in some cases, be the overriding parameter for foraging leatherbacks. This is a classic example where the presence of small prey in the diet of a large marine predator may reflect profitable foraging decisions if the relatively low energy intake per small individual prey is offset by high encounter rates and minimal capture and handling costs. This study provides, to our knowledge, the first quantitative estimates of intake rate for this species. PMID:22090203

Fossette, Sabrina; Gleiss, Adrian C; Casey, James P; Lewis, Andrew R; Hays, Graeme C

2012-06-23

119

Rationale and design of a randomized controlled trial of varenicline directly observed therapy delivered in methadone clinics  

PubMed Central

Background Tobacco cessation medication adherence is one of the few factors shown to improve smoking cessation rates among methadone-maintained smokers, but interventions to improve adherence to smoking cessation medications have not yet been tested among methadone treatment patients. Methadone clinic-based, directly observed therapy (DOT) programs for HIV and tuberculosis improve adherence and clinical outcomes, but have not been evaluated for smoking cessation. We describe a randomized controlled trial to evaluate whether a methadone clinic-based, directly observed varenicline therapy program increases adherence and tobacco abstinence among opioid-dependent drug users receiving methadone treatment. Methods/Design We plan to enroll 100 methadone-maintained smokers and randomize them to directly observed varenicline dispensed with daily methadone doses or treatment as usual (self-administered varenicline) for 12 weeks. Our outcome measures are: 1) pill count adherence and 2) carbon monoxide-verified tobacco abstinence. We will assess differences in adherence and abstinence between the two treatment arms using repeated measures models. Discussion This trial will allow for rigorous evaluation of the efficacy of methadone clinic-based, directly observed varenicline for improving adherence and smoking cessation outcomes. This detailed description of trial methodology can serve as a template for the development of future DOT programs and can guide protocols for studies among opioid-dependent smokers receiving methadone treatment. Trial Registration clinicaltrials.gov NCT01378858

2014-01-01

120

Instructional Interactions of Kindergarten Mathematics Classrooms: Validating a Direct Observation Instrument  

ERIC Educational Resources Information Center

In this paper, the authors report research focused directly on the validation of the Coding of Academic Teacher-Student interactions (CATS) direct observation instrument. They use classroom information gathered by the CATS instrument to better understand the potential mediating variables hypothesized to influence student achievement. Their study's…

Doabler, Christian; Smolkowski, Keith; Fien, Hank; Kosty, Derek B.; Cary, Mari Strand

2010-01-01

121

Nature of Fluctuations on Directional Discontinuities Inside a Solar Ejection: Wind and IMP 8 Observations  

NASA Technical Reports Server (NTRS)

A solar ejection passed the Wind spacecraft between December 23 and 26, 1996. On closer examination, we find a sequence of ejecta material, as identified by abnormally low proton temperatures, separated by plasmas with typical solar wind temperatures at 1 AU. Large and abrupt changes in field and plasma properties occurred near the separation boundaries of these regions. At the one boundary we examine here, a series of directional discontinuities was observed. We argue that Alfvenic fluctuations in the immediate vicinity of these discontinuities distort minimum variance normals, introducing uncertainty into the identification of the discontinuities as either rotational or tangential. Carrying out a series of tests on plasma and field data including minimum variance, velocity and magnetic field correlations, and jump conditions, we conclude that the discontinuities are tangential. Furthermore, we find waves superposed on these tangential discontinuities (TDs). The presence of discontinuities allows the existence of both surface waves and ducted body waves. Both probably form in the solar atmosphere where many transverse nonuniformities exist and where theoretically they have been expected. We add to prior speculation that waves on discontinuities may in fact be a common occurrence. In the solar wind, these waves can attain large amplitudes and low frequencies. We argue that such waves can generate dynamical changes at TDs through advection or forced reconnection. The dynamics might so extensively alter the internal structure that the discontinuity would no longer be identified as tangential. Such processes could help explain why the occurrence frequency of TDs observed throughout the solar wind falls off with increasing heliocentric distance. The presence of waves may also alter the nature of the interactions of TDs with the Earth's bow shock in so-called hot flow anomalies.

Vasquez, Bernard J.; Farrugia, Charles J.; Markovskii, Sergei A.; Hollweg, Joseph V.; Richardson, Ian G.; Ogilvie, Keith W.; Lepping, Ronald P.; Lin, Robert P.; Larson, Davin; White, Nicholas E. (Technical Monitor)

2001-01-01

122

Simultaneous Measurements of direct, semi-direct and indirect aerosol forcing with Stacked Autonomous UAVs: A New Observing Platform  

NASA Astrophysics Data System (ADS)

We report here first time demonstration with three autonomously flying Unmanned Aerial Vehicles (UAVs) of cloudy sky albedo, transmission atmospheric solar absorption, aerosol and cloud droplet concentrations and number densities. From these direct measurements we derive the direct, semi-direct and the first indirect aerosol forcing. The observing system consisted of 3 light weight UAVs, instrumented with miniaturized instruments (Roberts et al, 2006; Ramana et al, 2006; Corrigan et al 2006) for measuring aerosol concentrations and size distribution, cloud microphysical properties, black carbon concentration and broad band and narrow band solar fluxes. The airborne measurements were validated and augmented by the Atmospheric Brown Clouds Maldives Climate Observatory (ABC_MCO) in the island of Hanimaadhoo in the N. Indian Ocean (Corrigan et al, 2006; Ramana and Ramanathan 2006). The campaign was conducted during March and early April of 2006 when this region is subject to long range transport of pollution from S. Asia. In the stacked 3_UAV configuration, one flew in the boundary layer below clouds to characterize the aerosols feeding the clouds and the transmission of solar radiation by the absorbing aerosol layer and clouds above; the second inside the trade cumulus clouds to directly observe the fully nucleated cloud drop size and concentrations and total liquid water content; and the third above the cloud to determine the incoming solar and the reflected solar radiation. The 3-UAVs were programmed to sample the same region(or clouds) within seconds of each other, thus providing unique insights into how aerosols and boundary layer dynamics modulate the cloud microphysics and thus the albedo and solar absorption of cloudy skies in the planet. The period of observations also included a major dust-soot event which revealed a large increase in atmospheric solar absorption. We will present results on how 3- dimensional clouds with absorbing aerosols modulate atmospheric solar absorption, cloud microphysical properties, cloudy sky surface and TOA forcing and surface solar forcing. asia.ucsd.edu/MAC/secure/Index.htm

Ramanathan, V.; Roberts, G.; Ramana, M. V.; Corrigan, C.; Nguyen, H.

2006-12-01

123

Generalizability of Classroom Behavior Problem and On-Task Scores from the Direct Observation Form  

ERIC Educational Resources Information Center

The present study used generalizability theory to investigate the dependability of systematic observations of students' problem behavior and on-task behavior in classrooms. The Direct Observation Form (McConaughy & Achenbach, 2009) was used with a sample of 24, 6- to-11-year-old children attending 18 different elementary schools. The participants…

Volpe, Robert J.; McConaughy, Stephanie H.; Hintze, John M.

2009-01-01

124

Direct observation of PFPE lubricant molecules by cryogenic AFM under ultra-high vacuum  

Microsoft Academic Search

Surface lubrication is one of the essential technologies in modern magnetic disk systems and improvement of the surface lubrication is very important in the development of next generation systems. In this study, we used AFM for the direct observation of perfluoropolyether (PFPE) lubricant molecules on atomically flat surfaces. We used a cryogenic non-contact AFM to observe the molecules in a

Takayuki Nakakawaji; Mina Amo; Tomoshige Sato; Naoyuki Torita; Teiji Kato

2006-01-01

125

Direct observation of biting for studying grazing behavior of goats and llamas on garrigue rangelands  

Microsoft Academic Search

In any heterogeneous environment, classical methods used to estimate daily DMI and daily diets of grazing animals are difficult to implement. To investigate the grazing behavior of a goat and a llama, feeding on the garrigue in their respective flock, we therefore used a technique based on direct observation of biting. The observations were carried out in spring and early

B. Dumont; M. Meuret; M. Prud'hon

1995-01-01

126

Direct observation of cavitation fields at 23 and 515 kHz.  

PubMed

Direct observation of cavitation fields using photography, sonoluminescence and luminol "mapping" is reported for a 23 kHz horn sonicator and a 515 kHz plate transducer system. The effect of sound intensity and added surfactant on the cavitation fields is described. The observations support previously reported results suggesting significant differences in the cavitation fields between the two sonication systems. PMID:19464940

Price, Gareth J; Harris, Naomi K; Stewart, Alison J

2010-01-01

127

The Stochastic Engine Initiative: Improving Prediction of Behavior in Geologic Environments We Cannot Directly Observe  

SciTech Connect

The stochastic engine uses modern computational capabilities to combine simulations with observations. We integrate the general knowledge represented by models with specific knowledge represented by data, using Bayesian inferencing and a highly efficient staged Metropolis-type search algorithm. From this, we obtain a probability distribution characterizing the likely configurations of the system consistent with existing data. The primary use will be optimizing knowledge about the configuration of a system for which sufficient direct observations cannot be made. Programmatic applications include underground systems ranging from environmental contamination to military bunkers, optimization of complex nonlinear systems, and timely decision-making for complex, hostile environments such as battlefields or the detection of secret facilities. We create a stochastic ''base representation'' of system configurations (states) from which the values of measurable parameters can be calculated using forward simulators. Comparison of these predictions to actual measurements drives embedded Bayesian inferencing, updating the distributions of states in the base representation using the Metropolis method. Unlike inversion methods that generate a single bestcase deterministic solution, this method produces all the likely solutions, weighted by their likelihoods. This flexible method is best applied to highly non-linear, multi-dimensional problems. Staging of the Metropolis searches permits us to run the simplest model systems, such as lithology estimators, at the lower stages. The majority of possible configurations are thus eliminated from further consideration by more complex simulators, such as flow and transport models. Because the method is fully automated, large data sets of a variety of types can be used to refine the system configurations. The most important prerequisites for optimal use of this method are well-characterized forward simulators, realistic base representations, and most importantly an ability to obtain disparate data sets that are directly affected by the system configuration. Our initial earth-sciences application uses models for lithology, flow and transport, geochemistry, and geophysical imaging; the system configuration (base representation) being refined is the rock type at each underground location. In the initial stages of this initiative we demonstrated a two-stage analysis of synthetic Electrical Resistance Tomography (ERT) data and hydraulic flow information (Newmark et al., 2002). We used these results to develop algorithms that improve efficiency of the Metropolis search and provide accurate diagnostic evaluation during the search. Using actual data from a highly contaminated A/M outfall and solvent tank storage areas at the Savannah River Site (SRS), we used the stochastic engine to resolve lithology using ERT data. SRS will use these methods in their design and implementation of steam cleanup of the largest trichloroethylene (TCE) source in the Department of Energy (DOE) complex. We have implemented ''soft conditioning'' algorithms that allow us to use a variety of data types to control the initial representations, and most importantly, to use the final distribution resulting from one stochastic engine analysis as the initial distribution for a subsequent analysis. We have created a web-based interface that will allow collaborators like SRS to enter data and observe results of calculations on Lawrence Livermore National Laboratory (LLNL) supercomputers in an interactive mode. All engine functions operate in three dimensions, and a parallel implementation on Linux cluster machines is in initial testing. The method will be extended to include active process analysis, in which an ongoing data stream is used to continuously update the understanding of the system configuration. Applications to other types of state spaces, such as chemical parameters in a reacting system or atmospheric plume movement, are being evaluated.

Aines, R; Nitao, J; Newmark, R; Carle, S; Ramirez, A; Harris, D; Johnson, J; Johnson, V; Ermak, D; Sugiyama, G; Hanley, W; Sengupta, S; Daily, W; Glaser, R; Dyer, K; Fogg, G; Zhang, Y; Yu, Z; Levine, R

2002-05-09

128

Direct observation of the transition from indirect to direct bandgap in atomically thin epitaxial MoSe2.  

PubMed

Quantum systems in confined geometries are host to novel physical phenomena. Examples include quantum Hall systems in semiconductors and Dirac electrons in graphene. Interest in such systems has also been intensified by the recent discovery of a large enhancement in photoluminescence quantum efficiency and a potential route to valleytronics in atomically thin layers of transition metal dichalcogenides, MX2 (M = Mo, W; X = S, Se, Te), which are closely related to the indirect-to-direct bandgap transition in monolayers. Here, we report the first direct observation of the transition from indirect to direct bandgap in monolayer samples by using angle-resolved photoemission spectroscopy on high-quality thin films of MoSe2 with variable thickness, grown by molecular beam epitaxy. The band structure measured experimentally indicates a stronger tendency of monolayer MoSe2 towards a direct bandgap, as well as a larger gap size, than theoretically predicted. Moreover, our finding of a significant spin-splitting of ? 180 meV at the valence band maximum of a monolayer MoSe2 film could expand its possible application to spintronic devices. PMID:24362235

Zhang, Yi; Chang, Tay-Rong; Zhou, Bo; Cui, Yong-Tao; Yan, Hao; Liu, Zhongkai; Schmitt, Felix; Lee, James; Moore, Rob; Chen, Yulin; Lin, Hsin; Jeng, Horng-Tay; Mo, Sung-Kwan; Hussain, Zahid; Bansil, Arun; Shen, Zhi-Xun

2014-02-01

129

Direct in situ observation of structural transition driven actuation in VO2 utilizing electron transparent cantilevers  

NASA Astrophysics Data System (ADS)

Direct imaging and quantification of actuation in nanostructures that undergo structural phase transitions could advance our understanding of collective phenomena in the solid state. Here, we demonstrate visualization of structural phase transition induced actuation in a model correlated insulator vanadium dioxide by in situ Fresnel contrast imaging of electron transparent cantilevers. We quantify abrupt, reversible cantilever motion occurring due to the stress relaxation across the structural transition from a monoclinic to tetragonal phase with increasing temperature. Deflections measured in such nanoscale cantilevers can be directly correlated with macroscopic stress measurements by wafer curvature studies as well as temperature dependent electrical conduction allowing one to interrogate lattice dynamics across length scales.

Viswanath, B.; Ramanathan, Shriram

2013-07-01

130

Direct observation of multiple tautomers of oxythiamine and their recognition by the thiamine pyrophosphate riboswitch.  

PubMed

Structural diversification of canonical nucleic acid bases and nucleotide analogues by tautomerism has been proposed to be a powerful on/off switching mechanism allowing regulation of many biological processes mediated by RNA enzymes and aptamers. Despite the suspected biological importance of tautomerism, attempts to observe minor tautomeric forms in nucleic acid or hybrid nucleic acid-ligand complexes have met with challenges due to the lack of sensitive methods. Here, a combination of spectroscopic, biochemical, and computational tools probed tautomerism in the context of an RNA aptamer-ligand complex; studies involved a model ligand, oxythiamine pyrophosphate (OxyTPP), bound to the thiamine pyrophosphate (TPP) riboswitch (an RNA aptamer) as well as its unbound nonphosphorylated form, oxythiamine (OxyT). OxyTPP, similarly to canonical heteroaromatic nucleic acid bases, has a pyrimidine ring that forms hydrogen bonding interactions with the riboswitch. Tautomerism was established using two-dimensional infrared (2D IR) spectroscopy, variable temperature FTIR and NMR spectroscopies, binding isotope effects (BIEs), and computational methods. All three possible tautomers of OxyT, including the minor enol tautomer, were directly identified, and their distributions were quantitated. In the bound form, BIE data suggested that OxyTPP existed as a 4'-keto tautomer that was likely protonated at the N1'-position. These results also provide a mechanistic framework for understanding the activation of riboswitch in response to deamination of the active form of vitamin B1 (or TPP). The combination of methods reported here revealing the fine details of tautomerism can be applied to other systems where the importance of tautomerism is suspected. PMID:24252063

Singh, Vipender; Peng, Chunte Sam; Li, Deyu; Mitra, Koyel; Silvestre, Katherine J; Tokmakoff, Andrei; Essigmann, John M

2014-01-17

131

Direct observation of grain growth from molten silicon formed by micro-thermal-plasma-jet irradiation  

PubMed Central

Phase transformation of amorphous-silicon during millisecond annealing using micro-thermal-plasma-jet irradiation was directly observed using a high-speed camera with microsecond time resolution. An oval-shaped molten-silicon region adjacent to the solid phase crystallization region was clearly observed, followed by lateral large grain growth perpendicular to a liquid-solid interface. Furthermore, leading wave crystallization (LWC), which showed intermittent explosive crystallization, was discovered in front of the moving molten region. The growth mechanism of LWC has been investigated on the basis of numerical simulation implementing explosive movement of a thin liquid layer driven by released latent heat diffusion in a lateral direction.

Hayashi, Shohei; Fujita, Yuji; Kamikura, Takahiro; Sakaike, Kohei; Akazawa, Muneki; Ikeda, Mitsuhisa; Hanafusa, Hiroaki; Higashi, Seiichiro

2012-01-01

132

Direct observation of grain growth from molten silicon formed by micro-thermal-plasma-jet irradiation  

SciTech Connect

Phase transformation of amorphous-silicon during millisecond annealing using micro-thermal-plasma-jet irradiation was directly observed using a high-speed camera with microsecond time resolution. An oval-shaped molten-silicon region adjacent to the solid phase crystallization region was clearly observed, followed by lateral large grain growth perpendicular to a liquid-solid interface. Furthermore, leading wave crystallization (LWC), which showed intermittent explosive crystallization, was discovered in front of the moving molten region. The growth mechanism of LWC has been investigated on the basis of numerical simulation implementing explosive movement of a thin liquid layer driven by released latent heat diffusion in a lateral direction.

Hayashi, Shohei; Fujita, Yuji; Kamikura, Takahiro; Sakaike, Kohei; Akazawa, Muneki; Ikeda, Mitsuhisa; Hanafusa, Hiroaki; Higashi, Seiichiro [Department of Semiconductor Electronics and Integration Science, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530 (Japan)

2012-10-22

133

Direct observation method of individual single-stranded DNA molecules using fluorescent replication protein A.  

PubMed

Direct observation studies of single molecules have revealed molecular behaviors usually hidden in the ensemble and time-averaging of bulk experiments. Direct single DNA molecule analysis of DNA metabolism reactions such as DNA replication, repair, and recombination is necessary to fully understand these essential processes. Intercalation of fluorescent dyes such as YOYO-1 and SYTOX Orange has been the standard method for observing single molecules of double-stranded DNA (dsDNA), but effective fluorescent dyes for observing single molecules of single-stranded DNA (ssDNA) have not been found. To facilitate direct single-molecule observations of DNA metabolism reactions, it is necessary to establish methods for discriminating ssDNA and dsDNA. To observe ssDNA directly, we prepared a fusion protein consisting of the 70 kDa DNA-binding domain of replication protein A and enhanced yellow fluorescent protein (RPA-YFP). This fusion protein had ssDNA-binding activity. In our experiments, dsDNA was stained by SYTOX Orange and ssDNA by RPA-YFP, and we succeeded in staining ssDNA and dsDNA by using RPA-YFP and SYTOX Orange simultaneously. PMID:21225324

Oshige, Masahiko; Kawasaki, Shohei; Takano, Hiroki; Yamaguchi, Kouji; Kurita, Hirofumi; Mizuno, Takeshi; Matsuura, Shun-ichi; Mizuno, Akira; Katsura, Shinji

2011-05-01

134

Direct Observation of Circumstellar Clumps in High Mass X-Ray Binaries  

Microsoft Academic Search

The direct observation of clumpy circumstellar material in high mass X-ray binaries (HMXBs) is proposed. We propose to observe the two HMXBs V420 Aur and LS 5039, based on our optical data obtained over the past four years. With precision time- series photometry from the post-cryo IRAC instrument we expect the following scientific return: (i) Characterization of the size and

Gordon Sarty; Zoltan Balog; Laszlo Kiss; Kinwah Wu

2009-01-01

135

OBSERVER-BASED FLUX ESTIMATION MODELS IMPLEMENTATION FOR DIRECT FIELD ORIENTED CONTROL OF INDUCTION MACHINE DRIVES  

Microsoft Academic Search

In this paper two different observed-based flux estimation models to be used in the DFO control of induction machines are presented. The main idea relies on the use of estimation rather than direct measurement of the air gap flux, avoiding the inconveniences associated to the need of intrusive sensors. It is provided a performance analysis and comparison of both flux

Aitor J. Garrido; Francisco J. Maseda; Oscar Barambones

136

The Impact of Observation Duration on the Accuracy of Data Obtained from Direct Behavior Rating (DBR)  

ERIC Educational Resources Information Center

In this study, evaluation of direct behavior rating (DBR) occurred with regard to two primary areas: (a) accuracy of ratings with varied instrumentation (anchoring: proportional or absolute) and procedures (observation length: 5 min, 10 min, or 20 min) and (b) one-week test-retest reliability. Participants viewed video clips of a typical third…

Riley-Tillman, T. Chris; Christ, Theodore J.; Chafouleas, Sandra M.; Boice-Mallach, Christina H.; Briesch, Amy

2011-01-01

137

Directivity of High-Energy Emission from Solar Flares: Solar Maximum Mission Observations,  

National Technical Information Service (NTIS)

The data base consisting of flares detected by the gamma ray spectrometer (GRS) on board the Solar Maximum Mission (SMM) satellite is used to study the directivity of high-energy radiation. A number of observations strongly indicate that the high-energy e...

W. T. Vestrand D. J. Forrest E. L. Chupp E. Rieger G. H. Share

1987-01-01

138

Systematic Direct Observation of Time on Task as a Measure of Student Engagement  

ERIC Educational Resources Information Center

This study examines the relationship between systematic direct observation (SDO) of time on task (TOT) and student engagement as measured by a self-report task-specific measure. The research questions guiding the study are (a) what is the relationship between SDO of TOT and a self-report measure of student effort, and (b) what is the relationship…

Spanjers, Deanna M.; Burns, Matthew K.; Wagner, Angela R.

2008-01-01

139

Direct 23Na NMR observation of mixed cations residing inside a G-quadruplex channel.  

PubMed

We report direct (23)Na NMR observation for the presence of mixed cations (Na(+)/K(+), Na(+)/Rb(+), Na(+)/Sr(2+)) inside the G-quadruplex channel formed by the self-association of guanosine 5'-monophosphate at pH 8. PMID:17308634

Ida, Ramsey; Kwan, Irene C M; Wu, Gang

2007-02-28

140

UV Plasmonic Structures: Direct Observations of UV Extraordinary Optical Transmission and Localized Field Enhancement Through Nanoslits  

Microsoft Academic Search

The ultraviolet (UV) extraordinary optical transmission through nanoslit structures in the far field and the localized field enhancement in the near field are directly observed and compared with each other. Numerical modeling results are also presented, and the distribution properties of the UV Surface Plasmon polaritons (SPPs) are analyzed, showing agreement with the experiment results. These phenomena may enrich the

Qiaoqiang Gan; Liangcheng Zhou; Volkmar Dierolf; Filbert J. Bartoli

2009-01-01

141

From Directly Observed Therapy to Accompagnateurs: Enhancing AIDS Treatment Outcomes in Haiti and in Boston  

Microsoft Academic Search

Like tuberculosis, human immunodeficiency virus (HIV) disease is associated with poverty and social ine- qualities, conditions that hamper the delivery of care. Like tuberculosis, treatment of HIV infection requires multidrug regimens, and the causative agent acquires drug resistance, which can be transmitted to others. A pilot project in rural Haiti introduced DOT-HAART (directly observed therapy with highly active antiretroviral therapy)

H. L. Behforouz; P. E. Farmer; J. S. Mukherjee

2004-01-01

142

Ethical aspects of directly observed treatment for tuberculosis: a cross-cultural comparison  

PubMed Central

Background Tuberculosis is a major global public health challenge, and a majority of countries have adopted a version of the global strategy to fight Tuberculosis, Directly Observed Treatment, Short Course (DOTS). Drawing on results from research in Ethiopia and Norway, the aim of this paper is to highlight and discuss ethical aspects of the practice of Directly Observed Treatment (DOT) in a cross-cultural perspective. Discussion Research from Ethiopia and Norway demonstrates that the rigid enforcement of directly observed treatment conflicts with patient autonomy, dignity and integrity. The treatment practices, especially when imposed in its strictest forms, expose those who have Tuberculosis to extra burdens and costs. Socially disadvantaged groups, such as the homeless, those employed as day labourers and those lacking rights as employees, face the highest burdens. Summary From an ethical standpoint, we argue that a rigid practice of directly observed treatment is difficult to justify, and that responsiveness to social determinants of Tuberculosis should become an integral part of the management of Tuberculosis.

2013-01-01

143

Direct Observation of One-Dimensional Diffusion and Transcription by Escherichia coli RNA Polymerase  

Microsoft Academic Search

The dynamics of nonspecific and specific Escherichia coli RNA polymerase (RNAP)-DNA complexes have been directly observed using scanning force microscopy operating in buffer. To this end, imaging conditions had to be found in which DNA molecules were adsorbed onto mica strongly enough to be imaged, but loosely enough to be able to diffuse on the surface. In sequential images of

Martin Guthold; Xingshu Zhu; Claudio Rivetti; Guoliang Yang; Neil H. Thomson; Sandor Kasas; Helen G. Hansma; Bettye Smith; Paul K. Hansma; Carlos Bustamante

1999-01-01

144

Direct observation of the ice rule in demagnetized artificial kagome spin ice  

Microsoft Academic Search

Artificially designed magnetic structures have proven to be good analogs for the study of spin ice. We studied an artificial kagome spin ice, which is lithographically patterned using permalloy elements ˜23nm thick, ˜100nm wide, and ˜500nm long. Lorentz TEM is used to unambiguously determine each local pseudospin. Even with a rigorous randomizing demagnetization process, we directly observe an exclusive ice

Yi Qi; Todd Brintlinger; John Cumings; Paula Mellado; Oleg Tchernyshyov

2008-01-01

145

Directly Observed Interaction within Adolescent Romantic Relationships: What Have We Learned?  

ERIC Educational Resources Information Center

Review and conceptual analysis of the papers in this special issue calls attention to several important methodological and conceptual issues surrounding the direct observation of adolescent romantic couples. It also provides an important new foundation of knowledge about the nature of adolescents' romantic relationships. Connections with previous…

Welsh, Deborah P.; Shulman, Shmuel

2008-01-01

146

Directly observed relations in complete galaxy samples and the predictions of redshift-distance power laws  

PubMed Central

Directly observed relations in complete galaxy samples (apparent magnitude or diameter vs. redshift) are compared with the predictions of redshift-distance power laws. The predictions are obtained by an objective, nonparametric, statistically uniform, and fully reproducible procedure. In all cases the linear law fits even more poorly than a cubic law, and the optimal law is approximately quadratic. Even a 1.2 power law is conspicuously better-fitting than a linear law. The results of the present study in terms of directly measured quantities are consistent with and confirm earlier studies in terms of theoretical quantities such as absolute magnitudes and diameters. They show that there is no positive evidence for the Hubble law in manifestly fair galaxy samples and that the law can be reconciled with the data in complete samples only, if at all, by the adjunction of a tissue of ancillary hypotheses, none of which is capable of direct observational substantiation.

Segal, I. E.

1986-01-01

147

Analysis of multidimensional difference-of-Gaussians filters in terms of directly observable parameters  

PubMed Central

The difference-of-Gaussians (DOG) filter is a widely used model for the receptive field of neurons in the retina and lateral geniculate nucleus and is a potential model in general for responses modulated by an excitatory center with an inhibitory surrounding region. A DOG filter is defined by three standard parameters: the center and surround sigmas (which define the variance of the radially symmetric Gaussians) and the balance (which defines the linear combination of the two Gaussians). These parameters are not directly observable and are typically determined by nonlinear parameter estimation methods applied to the frequency response function. DOG filters show both low-pass (optimal response at zero frequency) and band-pass (optimal response at a non-zero frequency) behavior. This paper reformulates the DOG filter in terms of a directly observable parameter, the zero-crossing radius, and two new (but not directly observable) parameters. In the new two-dimensional parameter space, the exact region corresponding to band-pass behavior is determined. A detailed description of the frequency response characteristics of the DOG filter is obtained. It is also found that the directly observable optimal frequency and optimal gain (the ratio of the response at optimal frequency to the response at zero frequency) provide an alternate coordinate system for the band-pass region. Altogether, the DOG filter and its three standard implicit parameters can be determined by three directly observable values. The two-dimensional band-pass region is a potential tool for the analysis of populations of DOG filters (for example, populations of neurons in the retina or lateral geniculate nucleus) because the clustering of points in this parameter space may indicate an underlying organizational principle. This paper concentrates on circular Gaussians, but the results generalize to multidimensional radially symmetric Gaussians and are given as an appendix.

Cope, Davis; Blakeslee, Barbara; McCourt, Mark E.

2013-01-01

148

Direct laboratory observation of fluid distribution and its influence on acoustic properties of patchy saturated rocks  

NASA Astrophysics Data System (ADS)

Porous rocks in hydrocarbon reservoirs are often saturated with a mixture of two or more fluids. Interpretation of exploration seismograms requires understanding of the relationship between distribution of the fluids patches and acoustic properties of rocks. The sizes of patches as well as their distribution affect significantly the seismic response. If the size of the fluid patch is smaller than the diffusion wavelength then pressure equilibration is achieved and the bulk modulus of the rock saturated with a mixture is defined by the Gassmann equations (Gassmann, 1951) with the saturation-weighted average of the fluid bulk modulus given by Wood's law (Wood, 1955, Mavko et al., 1998). If the fluid patch size is much larger than the diffusion wavelength then there is no pressure communication between different patches. In this case, fluid-flow effects can be neglected and the overall rock may be considered equivalent to an elastic composite material consisting of homogeneous parts whose properties are given by Gassmann theory with Hill's equation for the bulk modulus (Hill, 1963, Mavko et al., 1998). At intermediate values of fluid saturation the velocity-saturation relationship is significantly affected by the fluid patch distribution. In order to get an improved understanding of factors influencing the patch distribution and the resulting seismic wave response we performed simultaneous measurements of P-wave velocities and rock sample CT imaging. The CT imaging allows us to map the fluid distribution inside rock sample during saturation (water imbibition). We compare the experimental results with theoretical predictions. In this paper we will present results of simultaneous measurements of longitudinal wave velocities and imaging mapping of fluid distribution inside rock sample during sample saturation. We will report results of two kinds of experiments: "dynamic" and "quasi static" saturation. In both experiments Casino Cores Otway Basin sandstone, Australia core samples (38 mm in diameter, approximately 60 mm long) were dried in oven under reduced pressure. In dynamic saturation experiments, samples were jacketed in the experimental cell, made from transparent for X-radiation material (PMMA). Distillate water was injected into the sample from the one side. Fluid distribution in such "dynamic" experiment: both spatial and time dependant was measured using X-ray Computer Tomograph (CT) with resolution 0.2 x 0.2 x 1 mm3. Velocities (Vp, and Vs) at ultrasonic frequency of 1 MHz, were measured in the direction perpendicular to initial direction of the fluid flow injection. Sample saturation was estimated from the CT results. In "quasi static" experiments samples were saturated during long period of time (over 2 weeks) to achieve uniform distribution of liquid inside the sample. Saturation was determined by measurement of the weight of water fraction. All experiments were performed at laboratory environments at temperature 25 C. Ultrasonic velocities and fluid saturations were measured simultaneously during water injection into sandstone core samples. The experimental results obtained on low-permeability samples show that at low saturation values the velocity-saturation dependence can be described by the Gassmann-Wood relationship. However, with increasing saturation a sharp increase of P-wave velocity is observed, eventually approaching the Gassmann-Hill relationship. We connect the characteristics of the transition behavior of the velocity-saturation relationships to the increasing size of the patches inside the rock sample. In particular, we show that for relatively large fluid injection rate this transition occurs at smaller degrees of saturation as compared with high injection rate. We model the experimental data using the so-called White model (Toms 2007) that assumes fluid patch distribution as a periodic assemblage of concentric spheres. We can observe reasonable agreement between experimental results and theoretical predictions of White's model. The results illustrate the non

Lebedev, M.; Clennell, B.; Pervukhina, M.; Shulakova, V.; Mueller, T.; Gurevich, B.

2009-04-01

149

A direct observation the asteroid's structure from deep interior to regolith: why and how do it?  

NASA Astrophysics Data System (ADS)

The internal structure of asteroids is still poorly known and has never been measured directly. Our knowledge is relying entirely on inferences from remote sensing observations of the surface, and theoretical modeling. Is the body a monolithic piece of rock or a rubble-pile, an aggregate of boulders held together by gravity and how much porosity it contains, both in the form of micro-scale or macro-scale porosity? What is the typical size of the constituent blocs? Are these blocs homogeneous or heterogeneous? Is the body a defunct or dormant comet and such MBC can become active? The body is covered by a regolith from whose properties remains largely unknown in term of depth, size distribution and spatial variation. Is resulting from fine particles re-accretion or from thermal fracturing? What are its coherent forces? How to model is thermal conductivity while this parameter is so important to estimate Yarkowsky and Yorp effects? Knowing asteroid deep interior and regolith structure is a key point for a better understanding of the asteroid accretion and dynamical evolution. There is no way to determine this from ground-based observation. Radar operating from a spacecraft is the only technique capable of achieving this science objective of characterizing the internal structure and heterogeneity from submetric to global scale for the science benefit as well as for the planetary defence and human exploration. The deep interior structure tomography requires low-frequency radar to penetrate throughout the complete body. The radar wave propagation delay and the received power are related to the complex dielectric permittivity (i.e to the composition and microporosity) and the small scale heterogeneities (scattering losses) while the spatial variation of the signal and the multiple paths provide information on the presence of heterogeneities (variations in composition or porosity), layers, ice lens. A partial coverage will provide "cuts" of the body when a dense coverage will allow a complete tomography. Two instruments concepts can be envisaged: A monostatic radar like Marsis/Mars Express (ESA) that will analyze radar waves transmitted by the orbiter and received after reflection by the asteroid, its surface and its internal structures. A bistatic radar like Consert/Rosetta (ESA that will analyze radar waves transmitted by a lander, propagated through the body and received by the orbiter. Imaging the first ~50 meters of the subsurface with a decimetric resolution to identify layering and to reconnect surface measurement to internal structure requires a higher frequency radar on Orbiter only, like Wisdom developed for ExoMars Rover (ESA) with a frequency ranging from 300 MHz up to 2.7 GHz. This paper reviews the science benefit of direct measurement of asteroid interior. Then radar concepts for both deep interior and near surface sounding and their science return are shown.

Herique, A.; Kofman, W. W.

2013-12-01

150

Unimolecular Thermal Decomposition of Phenol and d5-Phenol: Direct Observation of Cyclopentadiene Formation via Cyclohexadienone  

SciTech Connect

The pyrolyses of phenol and d{sub 5}-phenol (C{sub 6}H{sub 5}OH and C{sub 6}D{sub 5}OH) have been studied using a high temperature, microtubular ({mu}tubular) SiC reactor. Product detection is via both photon ionization (10.487 eV) time-of-flight mass spectrometry and matrix isolation infrared spectroscopy. Gas exiting the heated reactor (375 K-1575 K) is subject to a free expansion after a residence time in the {mu}tubular reactor of approximately 50-100 {micro}s. The expansion from the reactor into vacuum rapidly cools the gas mixture and allows the detection of radicals and other highly reactive intermediates. We find that the initial decomposition steps at the onset of phenol pyrolysis are enol/keto tautomerization to form cyclohexadienone followed by decarbonylation to produce cyclopentadiene; C{sub 6}H{sub 5}OH {yields} c-C{sub 6}H{sub 6} = O {yields} c-C{sub 5}H{sub 6} + CO. The cyclopentadiene loses a H atom to generate the cyclopentadienyl radical which further decomposes to acetylene and propargyl radical; c-C{sub 5}H{sub 6} {yields} c-C{sub 5}H{sub 5} + H {yields} HC {triple_bond} CH + HCCCH{sub 2}. At higher temperatures, hydrogen loss from the PhO-H group to form phenoxy radical followed by CO ejection to generate the cyclopentadienyl radical likely contributes to the product distribution; C{sub 6}H{sub 5}O-H {yields} C{sub 6}H{sub 5}O + H {yields} c-C{sub 5}H{sub 5} + CO. The direct decarbonylation reaction remains an important channel in the thermal decomposition mechanisms of the dihydroxybenzenes. Both catechol (o-HO-C{sub 6}H{sub 4}-OH) and hydroquinone (p-HO-C{sub 6}H{sub 4}-OH) are shown to undergo decarbonylation at the onset of pyrolysis to form hydroxycyclopentadiene. In the case of catechol, we observe that water loss is also an important decomposition channel at the onset of pyrolysis.

Scheer, A. M.; Mukarakate, C.; Robichaud, D. J.; Nimlos, M. R.; Carstensen, H. H.; Barney, E. G.

2012-01-28

151

Mid-Cretaceous charred fossil flowers reveal direct observation of arthropod feeding strategies.  

PubMed

Although plant-arthropod relationships underpin the dramatic rise in diversity and ecological dominance of flowering plants and their associated arthropods, direct observations of such interactions in the fossil record are rare, as these ephemeral moments are difficult to preserve. Three-dimensionally preserved charred remains of Chloranthistemon flowers from the Late Albian to Early Cenomanian of Germany preserve scales of mosquitoes and an oribatid mite with mouthparts inserted into the pollen sac. Mosquitoes, which today are frequent nectar feeders, and the mite were feeding on pollen at the time wildfire consumed the flowers. These findings document directly arthropod feeding strategies and their role in decomposition. PMID:21900310

Hartkopf-Fröder, Christoph; Rust, Jes; Wappler, Torsten; Friis, Else Marie; Viehofen, Agnes

2012-04-23

152

Observation of a highly directional ?-ray beam from ultrashort, ultraintense laser pulse interactions with solids  

NASA Astrophysics Data System (ADS)

Novel measurements of electromagnetic radiation above 10 MeV are presented for ultra intense laser pulse interactions with solids. A bright, highly directional source of ? rays was observed directly behind the target. The ? rays were produced by bremsstrahlung radiation from energetic electrons generated during the interaction. They were measured using the photoneutron reaction [63Cu(?,n)62Cu] in copper. The resulting activity was measured by coincidence counting the positron annihilation ? rays which were produced from the decay of 62Cu. New measurements of the bremsstrahlung radiation at 1019 W cm-2 are also presented.

Norreys, P. A.; Santala, M.; Clark, E.; Zepf, M.; Watts, I.; Beg, F. N.; Krushelnick, K.; Tatarakis, M.; Dangor, A. E.; Fang, X.; Graham, P.; McCanny, T.; Singhal, R. P.; Ledingham, K. W. D.; Creswell, A.; Sanderson, D. C. W.; Magill, J.; Machacek, A.; Wark, J. S.; Allott, R.; Kennedy, B.; Neely, D.

1999-05-01

153

Mid-Cretaceous charred fossil flowers reveal direct observation of arthropod feeding strategies  

PubMed Central

Although plant–arthropod relationships underpin the dramatic rise in diversity and ecological dominance of flowering plants and their associated arthropods, direct observations of such interactions in the fossil record are rare, as these ephemeral moments are difficult to preserve. Three-dimensionally preserved charred remains of Chloranthistemon flowers from the Late Albian to Early Cenomanian of Germany preserve scales of mosquitoes and an oribatid mite with mouthparts inserted into the pollen sac. Mosquitoes, which today are frequent nectar feeders, and the mite were feeding on pollen at the time wildfire consumed the flowers. These findings document directly arthropod feeding strategies and their role in decomposition.

Hartkopf-Froder, Christoph; Rust, Jes; Wappler, Torsten; Friis, Else Marie; Viehofen, Agnes

2012-01-01

154

Direct observation of NH2* reactions with oxygen, amino acids, and melanins.  

PubMed

We report the direct observation of the quenching of the weakly absorbing transient due to the amino radical by oxygen and, hence determine, by a totally direct method, the corresponding rate constant (k = (1.1 +/- 0.1) x 10(9) dm3 mol(-1) s(-1)). We also report the rate constants for the reactions of the amino radical with several amino acids and models of black eumelanin and blond/red phaeomelanin. These reactions lead to a mechanism, based on free radicals, that can explain why ammonia is useful in commercial hair (melanin) bleaching, avoiding excessive amino acid (hair protein) damage. PMID:18215026

Clarke, K; Edge, R; Johnson, V; Land, E J; Navaratnam, S; Truscott, T G

2008-02-14

155

Diffusion of a Highly-Charged Supramolecular Assembly: Direct Observation of Ion-Association in Water  

SciTech Connect

Understanding the solution behavior of supramolecular assemblies is essential for a full understanding of the formation and chemistry of synthetic host-guest systems. While the interaction between host and guest molecules is generally the focus of mechanistic studies of host-guest complexes, the interaction of the host-guest complex with other species in solution remains largely unknown, although in principle accessible by diffusion studies. Several NMR techniques are available to monitor diffusion and have recently been reviewed. Pulsed gradient spin-echo (PGSE) NMR methods have attracted increasing interest, since they allow diffusion coefficients to be measured with high accuracy; they have been successfully used with observation of {sup 7}Li and {sup 31}P nuclei as well as with {sup 1}H NMR. We report here the direct measurement of diffusion coefficients to observe ion-association interactions by counter cations with a highly-charged supramolecular assembly. Raymond and coworkers have described the design and chemistry of a class of metal-ligand supramolecular assemblies over the past decade. The [Ga{sub 4}L{sub 6}]{sup 12-} (L = 1,5-bis(2,3-dihydroxybenzamido)naphthalene) (1) (Figure 1) assembly has garnered the most attention, with the exploration of the dynamics and mechanism of guest exchange as well as the ability of 1 to achieve either stoichiometric or catalytic reactions inside its interior cavity. Recent studies have revealed the importance of counter cations in solution on the chemistry of 1. During the mechanistic study of the C-H bond activation of aldehydes by [Cp*Ir(PMe{sub 3})(olefin){sup +} {contained_in} 1]{sup 11-} a stepwise guest dissociation mechanism with an ion-paired intermediate was proposed. Similarly, in the mechanism for the hydrolysis of iminium cations generated from the 3-aza Cope rearrangement of enammonium cations in 1, the presence of an exterior ion association was part of the kinetic model. To further substantiate the indirect kinetic evidence for such ion-paired species, we sought to explore the solution behavior of 1 by studying the diffusion of 1 with varying alkali and tetraalkyl ammonium cations. For large molecules in solution, such as synthetic supramolecular assemblies, the diffusion behavior of host and guest molecules can provide valuable information on host-guest interaction. One characteristic feature of a stable host-guest complex is that the host and guest molecules diffuse at the same rate in solution; this has been observed in a number of supramolecular systems. In order to confirm that this system was suitable for study by diffusion NMR spectroscopy, a PGSE-DOSY spectrum was acquired of [NEt{sub 4} {contained_in} 1]{sup 11-} (Figure 2), which shows that the host and guest molecules diffuse at the same rate. Quantitative analysis of the data, from monitoring the integral of host and guest resonances as a function of applied gradient strength, gave identical diffusion coefficients, confirming that the host and guest molecules diffuse together.

University of California, Berkeley; Lawrence Berkeley National Laboratory; Raymond, Kenneth; Pluth, Michael D.; Tiedemann, Bryan E.F.; van Halbeek, Herman; Nunlist, Rudi; Raymond, Kenneth N.

2007-10-22

156

Direct observation of strain relaxation in iron layers on W(110) by time-resolved STM  

NASA Astrophysics Data System (ADS)

Time-resolved, in-situ-applied STM has been used to study the epitaxial growth of iron on W(110) at room temperature. By this way, sequences of STM images show directly the atomistics of the growth process on the surface. The first layer of iron on W(110) grows pseudomorphically without a preferred growth direction. Beginning with the second layer, the islands grow anisotropically with preferred growth in the [001]-direction. The generation of an ordered two-dimensional dislocation network starts at a coverage of 1.4 pseudomorphic monolayers to relax the misfit of 9.4%. A direct correlation of the creation of misfit dislocations in the second layer and the nucleation of the third-layer islands was found. Together with the onset of strain relaxation, the growth mode abruptly changes from layer-by-layer to statistical growth. A quantitative statistical analysis of the data allows to exactly determine the onset of relaxation, the vertical location of the dislocation lines, and the lateral extension of an island that is necessary to induce the formation of dislocations.

Jensen, C.; Reshöft, K.; Köhler, U.

1996-03-01

157

First direct observation of the Van Hove singularity in the tunnelling spectra of cuprates  

PubMed Central

In two-dimensional (2D) lattices, the electronic levels are unevenly spaced, and the density of states (DOS) displays a logarithmic divergence known as the Van Hove singularity (VHS). This is the case in particular for the layered cuprate superconductors. The scanning tunnelling microscope (STM) probes the DOS, and is therefore the ideal tool to observe the VHS. No STM study of cuprate superconductors has reported such an observation so far giving rise to a debate about the possibility of observing directly the normal state DOS in the tunnelling spectra. In this study, we show for the first time that the VHS is unambiguously observed in STM measurements performed on the cuprate Bi2Sr2CuO6+? (Bi-2201). Beside closing the debate, our analysis proves the presence of the pseudogap in the overdoped side of the phase diagram of Bi-2201 and discredits the scenario of the pseudogap phase crossing the superconducting dome.

Piriou, A.; Jenkins, N.; Berthod, C.; Maggio-Aprile, I.; Fischer, ?.

2011-01-01

158

Allowing patients to decide.  

PubMed

...allowing physicians to withhold life support and resuscitation because they feel it is futile, no matter how beneficent their intentions, would be an unwarranted step backwards toward the type of paternalism modern American society has turned away from. If we agree that all professional ethics must, in some way, be responsive to the society that profession serves, then in these most critical situations, the final decision must rest with the patient. PMID:11643203

Franklin, Cory

1993-01-01

159

Direct Observation of Pinning and Bowing of a Single Ferroelectric Domain Wall  

SciTech Connect

We have made a direct optical observation of pinning and bowing of a single 180{degree} ferroelectric domain wall under a uniform applied electric field using a collection mode near-field scanning optical microscope. The domain wall is observed to curve between the pinning defects, with a radius of curvature determined by the material parameters and the applied electric field. The change in birefringence with applied field is used to infer the orientation of the internal field at the domain wall. {copyright} {ital 1999} {ital The American Physical Society}

Yang, T.J.; Mohideen, U. [Department of Physics, University of California, Riverside, California 92521 (United States)] [Department of Physics, University of California, Riverside, California 92521 (United States); Gopalan, V. [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)] [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Swart, P.J. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1999-05-01

160

Direct observation of mass oscillations due to ablative Richtmyer-Meshkov instability in plastic targets.  

PubMed

We report the first direct experimental observation of the ablative Richtmyer-Meshkov instability. It manifests itself in oscillations of areal mass that occur during the shock transit time, which are caused by the "rocket effect" or dynamic overpressure characteristic of interaction between the laser absorption zone and the ablation front. With the 4-ns-long Nike KrF laser pulse and our novel diagnostic technique (monochromatic x-ray imaging coupled to a streak camera) we were able to register a peak and a valley of the areal-mass variation before the observed onset of the Rayleigh-Taylor growth. PMID:11800835

Aglitskiy, Y; Velikovich, A L; Karasik, M; Serlin, V; Pawley, C J; Schmitt, A J; Obenschain, S P; Mostovych, A N; Gardner, J H; Metzler, N

2001-12-24

161

Direct observations on generative cells isolated from pollen grains of Haemanthus katherinae baker.  

PubMed

Generative cells from mature pollen grains of Haemanthus katherinae Baker (African blood lily) were isolated by means of a simple squash method and observed by differential interference contrast (DIC), fluorescence and polarizing microscopy. The isolated cells appeared structurally similar to those observed in vivo and gave no evidence of a typical cell wall. Their viability was confirmed using the fluorescein diacetate test. The cell shape changed rapidly as the sucrose concentration of the medium was varied. The squash method of isolating generative cells holds promise for the direct and experimental study of these cells, especially in the living state. PMID:24248254

Zhou, C; Orndorff, K; Allen, R D; Demaggio, A E

1986-08-01

162

Direct Observation of Phagocytosis and NET-formation by Neutrophils in Infected Lungs using 2-photon Microscopy  

PubMed Central

After the gastrointestinal tract, the lung is the second largest surface for interaction between the vertebrate body and the environment. Here, an effective gas exchange must be maintained, while at the same time avoiding infection by the multiple pathogens that are inhaled during normal breathing. To achieve this, a superb set of defense strategies combining humoral and cellular immune mechanisms exists. One of the most effective measures for acute defense of the lung is the recruitment of neutrophils, which either phagocytose the inhaled pathogens or kill them by releasing cytotoxic chemicals. A recent addition to the arsenal of neutrophils is their explosive release of extracellular DNA-NETs by which bacteria or fungi can be caught or inactivated even after the NET releasing cells have died. We present here a method that allows one to directly observe neutrophils, migrating within a recently infected lung, phagocytosing fungal pathogens as well as visualize the extensive NETs that they have produced throughout the infected tissue. The method describes the preparation of thick viable lung slices 7 hours after intratracheal infection of mice with conidia of the mold Aspergillus fumigatus and their examination by multicolor time-lapse 2-photon microscopy. This approach allows one to directly investigate antifungal defense in native lung tissue and thus opens a new avenue for the detailed investigation of pulmonary immunity.

Hasenberg, Mike; Kohler, Anja; Bonifatius, Susanne; Jeron, Andreas; Gunzer, Matthias

2011-01-01

163

Three-dimensional atomic force microscopy: interaction force vector by direct observation of tip trajectory.  

PubMed

The prospect of a robust three-dimensional atomic force microscope (AFM) holds significant promise in nanoscience. Yet, in conventional AFM, the tip-sample interaction force vector is not directly accessible. We scatter a focused laser directly off an AFM tip apex to rapidly and precisely measure the tapping tip trajectory in three-dimensional space. This data also yields three-dimensional cantilever spring constants, effective masses, and hence, the tip-sample interaction force components via Newton's second law. Significant lateral forces representing 49 and 13% of the normal force (Fz = 152 ± 17 pN) were observed in common tapping mode conditions as a silicon tip intermittently contacted a glass substrate in aqueous solution; as a consequence, the direction of the force vector tilted considerably more than expected. When addressing the surface of a lipid bilayer, the behavior of the force components differed significantly from that observed on glass. This is attributed to the lateral mobility of the lipid membrane coupled with its elastic properties. Direct access to interaction components Fx, Fy, and Fz provides a more complete view of tip dynamics that underlie force microscope operation and can form the foundation of a three-dimensional AFM in a plurality of conditions. PMID:24099456

Sigdel, Krishna P; Grayer, Justin S; King, Gavin M

2013-11-13

164

Controllability and observability analysis for vertex domination centrality in directed networks.  

PubMed

Topological centrality is a significant measure for characterising the relative importance of a node in a complex network. For directed networks that model dynamic processes, however, it is of more practical importance to quantify a vertex's ability to dominate (control or observe) the state of other vertices. In this paper, based on the determination of controllable and observable subspaces under the global minimum-cost condition, we introduce a novel direction-specific index, domination centrality, to assess the intervention capabilities of vertices in a directed network. Statistical studies demonstrate that the domination centrality is, to a great extent, encoded by the underlying network's degree distribution and that most network positions through which one can intervene in a system are vertices with high domination centrality rather than network hubs. To analyse the interaction and functional dependence between vertices when they are used to dominate a network, we define the domination similarity and detect significant functional modules in glossary and metabolic networks through clustering analysis. The experimental results provide strong evidence that our indices are effective and practical in accurately depicting the structure of directed networks. PMID:24954137

Wang, Bingbo; Gao, Lin; Gao, Yong; Deng, Yue; Wang, Yu

2014-01-01

165

Controllability and observability analysis for vertex domination centrality in directed networks  

PubMed Central

Topological centrality is a significant measure for characterising the relative importance of a node in a complex network. For directed networks that model dynamic processes, however, it is of more practical importance to quantify a vertex's ability to dominate (control or observe) the state of other vertices. In this paper, based on the determination of controllable and observable subspaces under the global minimum-cost condition, we introduce a novel direction-specific index, domination centrality, to assess the intervention capabilities of vertices in a directed network. Statistical studies demonstrate that the domination centrality is, to a great extent, encoded by the underlying network's degree distribution and that most network positions through which one can intervene in a system are vertices with high domination centrality rather than network hubs. To analyse the interaction and functional dependence between vertices when they are used to dominate a network, we define the domination similarity and detect significant functional modules in glossary and metabolic networks through clustering analysis. The experimental results provide strong evidence that our indices are effective and practical in accurately depicting the structure of directed networks.

Wang, Bingbo; Gao, Lin; Gao, Yong; Deng, Yue; Wang, Yu

2014-01-01

166

Direct observation of transient Ostwald crystallization ordering from racemic serine solutions.  

PubMed

The Ostwald rule of stages describes the conjectured transitioning through metastable polymorphic crystal structures during crystallization. Direct observation of the Ostwald rule of stages using was performed using solutions of simple amino acids by second-order nonlinear optical imaging of chiral crystals (SONICC). SONICC, which is based on second-harmonic generation (SHG) imaging, enabled detection of homochiral microcrystals that survived only a few seconds before being converted to the more stable SHG-inactive polymorphic forms. PMID:20828149

Hall, Victoria J; Simpson, Garth J

2010-10-01

167

The Census of Social Institutions (CSI): A Public Health Direct Observation Measure of Local Land Use  

Microsoft Academic Search

This manuscript describes the development of the Census of Social Institutions (CSI), a reliable direct observation parcel-level\\u000a built environment measure. The CSI was used to measure all non-residential parcels (n?=?10,842) in 21 one-mile-radius neighborhoods centered around census block groups of varying income and ethnicity in a large\\u000a metropolitan area. One year test-retest and inter-rater intra-class correlations showed high reliability for

Katie M. Heinrich; Joseph Hughey; Anthony Randles; Dustin Wall; N. Andrew Peterson; Nattinee Jitnarin; LaVerne Berkel; Peter Eaton; Doug Bowles; C. Keith Haddock; W. S. Carlos Poston

2010-01-01

168

A direct observation of quark-gluon jet differences at LEP  

Microsoft Academic Search

Quark and gluon jets in e+e- three-jet events at LEP are identified using lepton tagging of quark jets, through observation of semi-leptonic charm and bottom quark decays. Events with a symmetry under transposition of the energies and directions of a quark and gluon jet are selected: these quark and gluon jets have essentially the same energy and event environment and

Gideon Alexander; J. Allison; P. P. Allport; K. J. Anderson; S. Arcelli; J. C. Armitage; P. Ashton; Alan Astbury; D A Axen; Georges Azuelos; G. A. Bahan; J. T. M. Baines; A. H. Ball; J. Banks; G. J. Barker; R. J. Barlow; J Richard Batley; G. Beaudoin; A. Beck; J. Becker; T. Behnke; K. W. Bell; G. Bella; Siegfried Bethke; O. Biebel; U. Binder; Ian J Bloodworth; P. Bock; H. M. Bosch; S. Bougerolle; B. B. Brabson; Horst Breuker; R. M. Brown; R. Brun; A. Buijs; Helfried J Burckhart; P. Capiluppi; R. K. Carnegie; A. A. Carter; J. R. Carter; C. Y. Chang; D. G. Charlton; J. T. M. Chrin; P. E. L. Clarke; I. Cohen; W. J. Collins; J. E. Conboy; M. Cooper; M. Couch; M. Coupland; M. Cuffiani; S. Dado; G. M. Dallavalle; S. de Jong; P. Debu; M. M. Deninno; A. Dieckmann; Michael Dittmar; M. S. Dixit; E. Duchovni; G. Duckeck; I. P. Duerdoth; D. J. P. Dumas; G. Eckerlin; P. A. Elcombe; P. G. Estabrooks; E. Etzion; Franco Luigi Fabbri; Margret Fincke-Keeler; H. M. Fischer; D. G. Fong; C. Fukunaga; A. Gaidot; O. Ganel; J. W. Gary; J. Gascon; R. F. McGowan; N. I. Geddes; C. Geich-Gimbel; S. W. Gensler; F. X. Gentit; G. Giacomelli; V. Gibson; W. R. Gibson; J. D. Gillies; J. Goldberg; M. J. Goodrick; W. Gorn; C. Grandi; E. Gross; J. Hagemann; G. G. Hanson; M. Hansroul; C. K. Hargrove; P. F. Harrison; J. Hart; P. M. Hattersley; M. Hauschild; C. M. Hawkes; E. Heflin; R. J. Hemingway; R. D. Heuer; J. C. Hill; S. J. Hillier; D. A. Hinshaw; C. Ho; J. D. Hobbs; P. R. Hobson; D. Hochman; B. Holl; R. J. Homer; S. R. Hou; C. P. Howarth; R. E. Hughes-Jones; R. Humbert; P. Igo-Kemenes; H. Ihssen; D. C. Imrie; L. Janissen; A. Jawahery; P. W. Jeffreys; H. Jeremie; M. Jimack; M. Jobes; R. W. L. Jones; P. Jovanovic; D. Karlen; K. Kawagoe; T. Kawamoto; R G Kellogg; R. G. Kellogg; B. W. Kennedy; C. Kleinwort; D. E. Klem; T. Kobayashi; T. P. Kokott; S. Komamiya; L. Köpke; R. Kowalewski; H. Kreutzmann; J. von Krogh; J. Kroll; M. Kuwano; P. Kyberd; G. D. Lafferty; F. Lamarche; W. J. Larson; J. G. Layter; P. Le Du; P. Leblanc; A. M. Lee; M. H. Lehto; D. Lellouch; P. Lennert; C. Leroy; L. Lessard; S. Levegrün; L. Levinson; S. L. Lloyd; F. K. Loebinger; J. M. Lorah; B. Lorazo; M. J. Losty; X. C. Lou; J. Ludwig; M. Mannelli; S. Marcellini; G. Maringer; A. J. Martin; J. P. Martin; T. Mashimo; P. Mättig; U. Maur; T. J. McMahon; J. R. McNutt; F. Meijers; D. Menszner; F. S. Merritt; H. Mes; A. Michelini; R. P. Middleton; G. Mikenberg; J. Mildenberger; D. J. Miller; C. Milstene; R. Mir; W. Mohr; C. Moisan; A. Montanari; T. Mori; M. W. Moss; T. Mouthuy; P. G. Murphy; B. Nellen; H. H. Nguyen; M. Nozaki; S. W. O'Neale; B. P. O'Neill; F. G. Oakham; F. Odorici; M. Ogg; H. O. Ogren; H. Oh; C. J. Oram; M. J. Oreglia; S. Orito; J. P. Pansart; B. Panzer-Steindel; P. Paschievici; G. N. Patrick; S. J. Pawley; P. Pfister; J. E. Pilcher; J. L. Pinfold; D. E. Plane; P. Poffenberger; B. Poli; A. Pouladdej; E. Prebys; T. W. Pritchard; H. Przysiezniak; G. Quast; M. W. Redmond; D. L. Rees; K. Riles; S. A. Robins; D. Robinson; A. Rollnik; J. M. Roney; S. Rossberg; A. M. Rossi; P. Routenburg; K. Runge; O. Runolfsson; D. R. Rust; S. Sanghera; M. Sasaki; A. D. Schaile; O. Schaile; W. Schappert; P. Scharff-Hansen; P. Schenk; H. von der Schmitt; S. Schreiber; J. Schwarz; W. G. Scott; M. Settles; B. C. Shen; P. Sherwood; R. Shypit; A. Simon; G. P. Siroli; A. Skuja; A. M. Smith; T. J. Smith; G. A. Snow; Randall J Sobie; R. W. Springer; M. Sproston; K. Stephens; H. E. Stier; D. Strom; H. Takeda; T. Takeshita; P. Taras; S. Tarem; P. Teixeira-Dias; N. J. Thackray; T. Tsukamoto; M. F. Turner; G. Tysarczyk-Niemeyer; D. van den Plas; R. van Kooten; G. J. Vandalen; G. Vasseur; C. J. Virtue; A. Wagner; C. Wahl; J. P. Walker; C. P. Ward; D. R. Ward; P. M. Watkins; A. T. Watson; N. K. Watson; M. Weber; S. Weisz; P. S. Wells; N. Wermes; M. Weymann; M. A. Whalley; G. W. Wilson; J. A. Wilson; I Wingerter-Seez; V.-H. Winterer; N. C. Wood; S A Wotton; T. R. Wyatt; R. Yaari; Y. Yang; G. Yekutieli; I E Zacharov; W. Zeuner; G. T. Zorn

1991-01-01

169

Direct Observation of Charge Transfer in Double-Perovskite-Like RbMn[Fe(CN)6  

Microsoft Academic Search

The charge density distribution has been determined for a transition metal cyanide, RbMn[Fe(CN)6], by means of the maximum entropy Rietveld method combined with the highly angularly resolved synchrotron radiation x-ray powder diffraction at SPring-8 BL02B2. We directly observed a charge transfer from the Mn site to the Fe site in the low-temperature phase. On the basis of a local density

K. Kato; Y. Moritomo; M. Takata; M. Sakata; M. Umekawa; N. Hamada; S. Ohkoshi; H. Tokoro; K. Hashimoto

2003-01-01

170

Direct observations of basin-wide acidification of the North Pacific Ocean  

Microsoft Academic Search

Global ocean acidification is a prominent, inexorable change associated with rising levels of atmospheric CO2. Here we present the first basin-wide direct observations of recently declining pH, along with estimates of anthropogenic and non-anthropogenic contributions to that signal. Along 152°W in the North Pacific Ocean (22–56°N), pH changes between 1991 and 2006 were essentially zero below about 800 m depth.

Robert H. Byrne; Sabine Mecking; Richard A. Feely; Xuewu Liu

2010-01-01

171

Direct observations of basin-wide acidification of the North Pacific Ocean  

Microsoft Academic Search

Global ocean acidification is a prominent, inexorable change associated with rising levels of atmospheric CO2. Here we present the first basin-wide direct observations of recently declining pH, along with estimates of anthropogenic and non-anthropogenic contributions to that signal. Along 152°W in the North Pacific Ocean (22-56°N), pH changes between 1991 and 2006 were essentially zero below about 800 m depth.

Robert H. Byrne; Sabine Mecking; Richard A. Feely; Xuewu Liu

2010-01-01

172

Direct observation of the double Auger decay of a K hole  

Microsoft Academic Search

The double Auger (DA) decay of a K hole has been observed directly by detecting the two emitted electrons in coincidence. The hole was created in 37Cl following the electron-capture decay of 37Ar. The probability of DA decay, per Auger decay, with the two electrons both having an energy greater than 250 eV was found to be 3.7+\\/-0.2%. The DA

M. M. Hindi; Lin Zhu; Recep Avci; P. M. Miocinovic; R. L. Kozub; G. J. Lapeyre

1996-01-01

173

Direct observation of pyrolysis behavior of carbonaceous solids in a hot steam-argon environment  

Microsoft Academic Search

A unique flame-pyrolysis, direct-sampling mass spectrometer system has been applied to the observation of the primary and secondary pyrolysis of wood and its constituents. The system consists of a flat-flame burner which generates a hot column of steam-argon, into which samples to be pyrolyzed are introduced or suspended. A free-jet, molecular-beam, mass spectrometric sampling system is positioned relative to the

T. A. Milne; M. N. Soltys

1982-01-01

174

Direct Observation of Vacancies and Local Thermal Vibration in Thermoelectric Rhenium Silicide  

NASA Astrophysics Data System (ADS)

The crystal structure of rhenium silicide with an anomalous ordered arrangement of vacancies has been investigated by utilizing spherical-aberration (Cs)-corrected scanning transmission electron microscopy (STEM). Using Cs-corrected STEM imaging, we directly observe for the first time ordered silicon vacancies in thermoelectric rhenium silicide accompanied by anomalously large local thermal vibration (``rattling'' motion) of silicon atoms in their adjacent sites.

Harada, Shunta; Tanaka, Katsushi; Kishida, Kyosuke; Okamoto, Norihiko L.; Endo, Noriaki; Okunishi, Eiji; Inui, Haruyuki

2012-03-01

175

Participant observation of time allocation, direct patient contact and simultaneous activities in hospital physicians  

PubMed Central

Background Hospital physicians' time is a critical resource in medical care. Two aspects are of interest. First, the time spent in direct patient contact – a key principle of effective medical care. Second, simultaneous task performance ('multitasking') which may contribute to medical error, impaired safety behaviour, and stress. There is a call for instruments to assess these aspects. A preliminary study to gain insight into activity patterns, time allocation and simultaneous activities of hospital physicians was carried out. Therefore an observation instrument for time-motion-studies in hospital settings was developed and tested. Methods 35 participant observations of internists and surgeons of a German municipal 300-bed hospital were conducted. Complete day shifts of hospital physicians on wards, emergency ward, intensive care unit, and operating room were continuously observed. Assessed variables of interest were time allocation, share of direct patient contact, and simultaneous activities. Inter-rater agreement of Kappa = .71 points to good reliability of the instrument. Results Hospital physicians spent 25.5% of their time at work in direct contact with patients. Most time was allocated to documentation and conversation with colleagues and nursing staff. Physicians performed parallel simultaneous activities for 17–20% of their work time. Communication with patients, documentation, and conversation with colleagues and nursing staff were the most frequently observed simultaneous activities. Applying logit-linear analyses, specific primary activities increase the probability of particular simultaneous activities. Conclusion Patient-related working time in hospitals is limited. The potential detrimental effects of frequently observed simultaneous activities on performance outcomes need further consideration.

Weigl, Matthias; Muller, Andreas; Zupanc, Andrea; Angerer, Peter

2009-01-01

176

Direct observation of Space Shuttle water vapour exhaust plumes by Odin/SMR  

NASA Astrophysics Data System (ADS)

Odin/SMR measurements of the strong 557 GHz emission line of water vapour allow the retrieval of this species even at altitudes in the upper mesosphere and lower thermosphere. Typically the signal-to-noise ratio is poor at altitudes above 100 km and averaging is required to get sensible results at these altitudes. However the extraordinary concentrations inside the Space Shuttle exhaust plumes allow the retrieval of single water profiles with good statistics also at altitudes above 100 km. Since the start of the Odin mission 2001 in total 60 plume signatures could be detected after 8 Space Shuttle launches, even if Odin/SMR measurements of the 557 GHz band are performed only with larger time intervals. Plumes signatures were observed between a half day to more than two days after the Space Shuttle launch, reaching as far as to 75°N. The plume peak values are typically observed between 95 km and 105 km with concentrations of a couple of ppmv, i.e. roughly a factor 50 was is normally observed. These values describe an average over ~400 km (length) x 4 km (width) x 4 km (height) at the tangent altitude, indicating that the concentrations in the plume peak region are much higher.

Lossow, S.; Urban, J.; Murtagh, D. P.; Eriksson, P.

2010-12-01

177

The Generalizability of Systematic Direct Observations across Time and Setting: A Preliminary Investigation of the Psychometrics of Behavioral Observation. General Articles  

ERIC Educational Resources Information Center

This study examined the generalizability of systematic direct observation across setting and time. Participants included 14 students from an intact inclusionary fifth grade classroom. On-task/off-task behavior was directly observed using momentary time-sampling recording, twice a day, for 10 school days. Using Generalizability (G) theory, results…

Hintze, John M.; Matthews, William J.

2004-01-01

178

Direct observation of pyrolysis behavior of carbonaceous solids in a hot steam-argon environment  

SciTech Connect

A unique flame-pyrolysis, direct-sampling mass spectrometer system has been applied to the observation of the primary and secondary pyrolysis of wood and its constituents. The system consists of a flat-flame burner which generates a hot column of steam-argon, into which samples to be pyrolyzed are introduced or suspended. A free-jet, molecular-beam, mass spectrometric sampling system is positioned relative to the pyrolyzing surface so that primary products can be observed as well as their secondary cracking in hot gases. Typical primary pyrolysis product slates from cellulose, lignin, hemicellulose, wood, oil shale and coal will be shown, as well as the secondary cracking of cellulose products to olefins. The effect of potassium ions and sample dimension on primary pyrolysis of cellulose will be shown to illustrate the kind of real-time pyrolysis behavior that can readily be observed with our techniques.

Milne, T.A.; Soltys, M.N.

1982-02-01

179

Direct observation of ionic structure at solid-liquid interfaces: a deep look into the Stern Layer.  

PubMed

The distribution of ions and charge at solid-water interfaces plays an essential role in a wide range of processes in biology, geology and technology. While theoretical models of the solid-electrolyte interface date back to the early 20(th) century, a detailed picture of the structure of the electric double layer has remained elusive, largely because of experimental techniques have not allowed direct observation of the behaviour of ions, i.e. with subnanometer resolution. We have made use of recent advances in high-resolution Atomic Force Microscopy to reveal, with atomic level precision, the ordered adsorption of the mono- and divalent ions that are common in natural environments to heterogeneous gibbsite/silica surfaces in contact with aqueous electrolytes. Complemented by density functional theory, our experiments produce a detailed picture of the formation of surface phases by templated adsorption of cations, anions and water, stabilized by hydrogen bonding. PMID:24850566

Siretanu, Igor; Ebeling, Daniel; Andersson, Martin P; Stipp, S L Svane; Philipse, Albert; Stuart, Martien Cohen; van den Ende, Dirk; Mugele, Frieder

2014-01-01

180

Direct observation of ionic structure at solid-liquid interfaces: a deep look into the Stern Layer  

PubMed Central

The distribution of ions and charge at solid-water interfaces plays an essential role in a wide range of processes in biology, geology and technology. While theoretical models of the solid-electrolyte interface date back to the early 20th century, a detailed picture of the structure of the electric double layer has remained elusive, largely because of experimental techniques have not allowed direct observation of the behaviour of ions, i.e. with subnanometer resolution. We have made use of recent advances in high-resolution Atomic Force Microscopy to reveal, with atomic level precision, the ordered adsorption of the mono- and divalent ions that are common in natural environments to heterogeneous gibbsite/silica surfaces in contact with aqueous electrolytes. Complemented by density functional theory, our experiments produce a detailed picture of the formation of surface phases by templated adsorption of cations, anions and water, stabilized by hydrogen bonding.

Siretanu, Igor; Ebeling, Daniel; Andersson, Martin P.; Stipp, S. L. Svane; Philipse, Albert; Stuart, Martien Cohen; van den Ende, Dirk; Mugele, Frieder

2014-01-01

181

Directional and photometric observations of artificial earth satellites using the U.K. Satellite Laser Ranging System  

Microsoft Academic Search

The recent use of the U.K. Satellite Laser Ranging System in nonranging mode to obtain astrometric and photometric observations of artificial satellites is described. It is found that the system is capable of obtaining a series of directional normal points of accuracy about 5 arcsec throughout a pass of a close-earth satellite. Simultaneous with the directional observations photometric observations were

G. M. Appleby

1990-01-01

182

Direct observation of microtubule pushing by cortical dynein in living cells  

PubMed Central

Microtubules are under the influence of forces mediated by cytoplasmic dynein motors associated with the cell cortex. If such microtubules are free to move, they are rapidly transported inside cells. Here we directly observe fluorescent protein–labeled cortical dynein speckles and motile microtubules. We find that several dynein complex subunits, including the heavy chain, the intermediate chain, and the associated dynactin subunit Dctn1 (also known as p150glued) form spatially resolved, dynamic speckles at the cell cortex, which are preferentially associated with microtubules. Measurements of bleaching and dissociation kinetics at the cell cortex reveal that these speckles often contain multiple labeled dynein heavy-chain molecules and turn over rapidly within seconds. The dynamic behavior of microtubules, such as directional movement, bending, or rotation, is influenced by association with dynein speckles, suggesting a direct physical and functional interaction. Our results support a model in which rapid turnover of cell cortex–associated dynein complexes facilitates their search to efficiently capture and push microtubules directionally with leading plus ends.

Mazel, Tomas; Biesemann, Anja; Krejczy, Magda; Nowald, Janos; Muller, Olga; Dehmelt, Leif

2014-01-01

183

Apparatus for Direct Optical Fiber Through-Lens Illumination of Microscopy or Observational Objects  

NASA Technical Reports Server (NTRS)

In one embodiment of the invention, a microscope or other observational apparatus, comprises a hollow tube, a lens mounted to the tube, a light source and at least one flexible optical fiber having an input end and an output end. The input end is positioned to receive light from the light source, and the output end is positioned within the tube so as to directly project light along a straight path to the lens to illuminate an object to be viewed. The path of projected light is uninterrupted and free of light deflecting elements. By passing the light through the lens, the light can be diffused or otherwise defocused to provide more uniform illumination across the surface of the object, increasing the quality of the image of the object seen by the viewer. The direct undeflected and uninterrupted projection of light, without change of direction, eliminates the need for light-deflecting elements, such as beam-splitters, mirrors, prisms, or the like, to direct the projected light towards the object.

Kadogawa, Hiroshi (Inventor)

2001-01-01

184

Identification of an androgen response element in intron 8 of the sterol regulatory element-binding protein cleavage-activating protein gene allowing direct regulation by the androgen receptor.  

PubMed

Sterol regulatory element-binding proteins (SREBPs) are transcription regulators that play a pivotal role in intracellular lipid homeostasis. They are synthesized as inactive precursor proteins in the endoplasmic reticulum, where they are retained by SREBP cleavage-activating protein (SCAP), a sterol sensing protein that in turn is linked to a retention protein complex. Low intracellular sterol concentrations weaken the interaction of SCAP with its retention proteins and allow translocation of the SREBP.SCAP complex to the Golgi compartment where SREBP is proteolytically cleaved and activated. Previous studies on the mechanisms by which androgens provoke a coordinated activation of lipogenic pathways in prostate cancer cells have suggested an alternative pathway of activation in which androgens increase the expression of SCAP and favor translocation of the SREBP.SCAP complex to the Golgi apparatus by disturbing the balance between SCAP and its retention proteins. Here we show that the SCAP gene contains an androgen-responsive region located in intron 8. This region interacts directly with the androgen receptor and confers androgen responsiveness to promoter-reporter constructs transfected in LNCaP cells. It contains a noncanonical androgen response element GGAAGAaaaTGTACC that interacts not only with the androgen receptor but also with the glucocorticoid receptor and that also confers glucocorticoid responsiveness. The identification of a steroid response element in intron 8 of the SCAP gene further supports the contention that SCAP is a direct target for steroid hormone action. PMID:15133039

Heemers, Hannelore; Verrijdt, Guy; Organe, Sophie; Claessens, Frank; Heyns, Walter; Verhoeven, Guido; Swinnen, Johannes V

2004-07-16

185

An improved microscope stage for direct observation of freezing and freeze drying.  

PubMed

A microscope stage for observation of freezing and freeze drying is described. The stage uses thermoelectric (Peltier) heaters configured in two stages, with circulating fluid as a heat sink on the high temperature side. Lowest attainable sample temperature is about -47 degrees C. Principal advantages of this system are closed-loop control of stage temperature, rapid response to changes in temperature set point, and improved documentation of experiments by use of a video recorder system with a character generator which allows display of sample identity and temperature. Accuracy of measuring the sample temperature in the field of view was validated by comparing observed values of eutectic melting with published values for a series of solutes with eutectic temperatures in the range from -2 degrees C to -32 degrees C. Good agreement was obtained throughout this range. PMID:7971708

Nail, S L; Her, L M; Proffitt, C P; Nail, L L

1994-08-01

186

Direct observation of a highly spin-polarized organic spinterface at room temperature.  

PubMed

Organic semiconductors constitute promising candidates toward large-scale electronic circuits that are entirely spintronics-driven. Toward this goal, tunneling magnetoresistance values above 300% at low temperature suggested the presence of highly spin-polarized device interfaces. However, such spinterfaces have not been observed directly, let alone at room temperature. Thanks to experiments and theory on the model spinterface between phthalocyanine molecules and a Co single crystal surface, we clearly evidence a highly efficient spinterface. Spin-polarised direct and inverse photoemission experiments reveal a high degree of spin polarisation at room temperature at this interface. We measured a magnetic moment on the molecule's nitrogen ? orbitals, which substantiates an ab-initio theoretical description of highly spin-polarised charge conduction across the interface due to differing spinterface formation mechanisms in each spin channel. We propose, through this example, a recipe to engineer simple organic-inorganic interfaces with remarkable spintronic properties that can endure well above room temperature. PMID:23412079

Djeghloul, F; Ibrahim, F; Cantoni, M; Bowen, M; Joly, L; Boukari, S; Ohresser, P; Bertran, F; Le Fèvre, P; Thakur, P; Scheurer, F; Miyamachi, T; Mattana, R; Seneor, P; Jaafar, A; Rinaldi, C; Javaid, S; Arabski, J; Kappler, J-P; Wulfhekel, W; Brookes, N B; Bertacco, R; Taleb-Ibrahimi, A; Alouani, M; Beaurepaire, E; Weber, W

2013-01-01

187

Direct observation of a propagating spin wave induced by spin-transfer torque.  

PubMed

Spin torque oscillators with nanoscale electrical contacts are able to produce coherent spin waves in extended magnetic films, and offer an attractive combination of electrical and magnetic field control, broadband operation, fast spin-wave frequency modulation, and the possibility of synchronizing multiple spin-wave injection sites. However, many potential applications rely on propagating (as opposed to localized) spin waves, and direct evidence for propagation has been lacking. Here, we directly observe a propagating spin wave launched from a spin torque oscillator with a nanoscale electrical contact into an extended Permalloy (nickel iron) film through the spin transfer torque effect. The data, obtained by wave-vector-resolved micro-focused Brillouin light scattering, show that spin waves with tunable frequencies can propagate for several micrometres. Micromagnetic simulations provide the theoretical support to quantitatively reproduce the results. PMID:21873993

Madami, M; Bonetti, S; Consolo, G; Tacchi, S; Carlotti, G; Gubbiotti, G; Mancoff, F B; Yar, M A; Akerman, J

2011-10-01

188

Real-time direct observation of Li in LiCoO2 cathode material  

NASA Astrophysics Data System (ADS)

The direct observation of light elements such as Li is a challenge even for state-of-the-art electron microscopy techniques because such elements scatter electrons only weakly. Using the annular bright field scanning transmission electron microscopy imaging technique, we have simultaneously visualized columns of Li, O, and Co ions in the lithium-ion battery cathode material LiCoO2, which is one of the most important cathode materials for industrial applications. The annular bright field image exhibits a good signal-to-noise ratio and the image contrast is not reversed as the specimen thickness changes. The direct visualization of light elements in real time with this method represents an important breakthrough in characterizing the active materials in solid-state electrochemical devices.

Huang, Rong; Hitosugi, Taro; Findlay, Scott D.; Fisher, Craig A. J.; Ikuhara, Yumi H.; Moriwake, Hiroki; Oki, Hideki; Ikuhara, Yuichi

2011-01-01

189

Direct observation of a highly spin-polarized organic spinterface at room temperature  

PubMed Central

Organic semiconductors constitute promising candidates toward large-scale electronic circuits that are entirely spintronics-driven. Toward this goal, tunneling magnetoresistance values above 300% at low temperature suggested the presence of highly spin-polarized device interfaces. However, such spinterfaces have not been observed directly, let alone at room temperature. Thanks to experiments and theory on the model spinterface between phthalocyanine molecules and a Co single crystal surface, we clearly evidence a highly efficient spinterface. Spin-polarised direct and inverse photoemission experiments reveal a high degree of spin polarisation at room temperature at this interface. We measured a magnetic moment on the molecule's nitrogen ? orbitals, which substantiates an ab-initio theoretical description of highly spin-polarised charge conduction across the interface due to differing spinterface formation mechanisms in each spin channel. We propose, through this example, a recipe to engineer simple organic-inorganic interfaces with remarkable spintronic properties that can endure well above room temperature.

Djeghloul, F.; Ibrahim, F.; Cantoni, M.; Bowen, M.; Joly, L.; Boukari, S.; Ohresser, P.; Bertran, F.; Le Fevre, P.; Thakur, P.; Scheurer, F.; Miyamachi, T.; Mattana, R.; Seneor, P.; Jaafar, A.; Rinaldi, C.; Javaid, S.; Arabski, J.; Kappler, J. -P; Wulfhekel, W.; Brookes, N. B.; Bertacco, R.; Taleb-Ibrahimi, A.; Alouani, M.; Beaurepaire, E.; Weber, W.

2013-01-01

190

Direct assessment of groundwater vulnerability from single observations of multiple contaminants  

USGS Publications Warehouse

Groundwater vulnerability is a central concept in pollution risk assessment, yet its estimation has been largely a matter of expert judgment. This work applies a method for the direct calculation of vulnerability from monitoring well observations of pesticide concentrations. The method has two major advantages: it is independent of the compounds being examined, and it has a direct probabilistic interpretation making it ideal for risk assessment. The methodology was applied to data from a groundwater monitoring program in the midwestern United States. The distribution of the vulnerabilities was skewed toward zero. Spatial distribution of the vulnerabilities shows them to be controlled by both regional and local factors. Methods are presented for estimating the necessary sample sizes for vulnerability studies. The further application of the approach developed in this study to understanding groundwater pollution is discussed.

Worrall, F.; Kolpin, D. W.

2003-01-01

191

Direct observation of chemical reactions on single gold nanocrystals using surface plasmon spectroscopy.  

PubMed

Heterogeneous catalysts have been pivotal to the development of the modern chemical industry and are essential for catalysing many industrial reactions. However, reaction rates are different for every individual catalyst particle and depend upon each particle's morphology and size, crystal structure and composition. Measuring the rates of reaction on single nanocrystals will enable the role of catalyst structure to be quantified. Here, using surface plasmon spectroscopy, we have directly observed the kinetics of atomic deposition onto a single gold nanocrystal and also monitored electron injection and extraction during a redox reaction involving the oxidation of ascorbic acid on a gold nanocrystal surface. These results constitute the first direct measurement of the rates of redox catalysis on single nanocrystals. PMID:18838998

Novo, Carolina; Funston, Alison M; Mulvaney, Paul

2008-10-01

192

Technique to observe direct CP violation in D mesons using Bose symmetry and the Dalitz plot  

NASA Astrophysics Data System (ADS)

We present a new method to observe direct CP violation in D mesons using Bose symmetry and the Dalitz plot. We apply the method to processes such as B?D0D¯0P, where P is either a K or a ?. By choosing to reconstruct D mesons only through their decays into CP eigenstates, we show that any asymmetry in the Dalitz plot can arise only through direct CP violation. We further show how CP violation parameters can be determined. Since the approach involves only Bose symmetry, the method is applicable to any multibody process that involves D0D¯0 in the final state. We briefly discuss how B?D*D¯*P can also be used in a similar way. This method can also be applied to D0D¯0 in the final state from continuum cc¯ production.

Sahoo, Dibyakrupa; Sinha, Rahul; Deshpande, N. G.; Pakvasa, Sandip

2014-04-01

193

Direct observations of eddy turbulence at a ridge in the Southern Ocean  

NASA Astrophysics Data System (ADS)

Mesoscale turbulence in the ACC is concentrated where the current interacts with prominent bottom topography. An unusual region of high levels of turbulence is found downstream of the South-West Indian Ridge. It has been inferred that this turbulence consists largely of eddies generated at a fracture zone in the ridge. A dedicated research cruise to the region has now presented data that allow us for the first time to track these eddies and to describe them in hydrographic detail. We show that these eddies are at least 1000 m deep, have a diameter of 250 km, exhibit azimuthal speeds of up to 0.74 ms-1, have subsequent translation speeds of up to 0.09 ms-1 and consist of water masses derived from either north or south of the SAF and APF. Eddies in general are shown to advect in a north-eastward direction and dissipate before reaching a longitude of 40°E.

Ansorge, Isabelle J.; Lutjeharms, Johann R. E.

2005-07-01

194

Investigations on the mechanism of superlubricity achieved with phosphoric acid solution by direct observation  

NASA Astrophysics Data System (ADS)

In this work, the contact region between a Si3N4 ball and a SiO2 plate with the lubrication of phosphoric acid solution is observed directly by an optical microscope combined with a Raman microscope to understand the superlubricity mechanism. It is found that the wear on the friction surfaces mainly occurs at the beginning of the test and nearly disappears after the friction coefficient reduces to 0.05. When the superlubricity appears (? = 0.004), there is only a limited amount of solution available to the contact (forming starvation state), resulting in an ``H'' distribution surrounding the contact region. Moreover, it is observed that the hydrogen bond effect in the solution is enhanced with time going by, and finally a thin film with hydrogen bond network among H3PO4, H2PO4-, and H2O is formed on the friction surfaces, leading to the superlubricity. By employing this direct observation approach, the structure of the confined solution and the superlubricity mechanism of phosphoric acid solution are finally investigated and discussed.

Li, Jinjin; Ma, Liran; Zhang, Shaohua; Zhang, Chenhui; Liu, Yuhong; Luo, Jianbin

2013-09-01

195

Direct observation of aggregative nanoparticle growth: kinetic modeling of the size distribution and growth rate.  

PubMed

Direct observations of solution-phase nanoparticle growth using in situ liquid transmission electron microscopy (TEM) have demonstrated the importance of "non-classical" growth mechanisms, such as aggregation and coalescence, on the growth and final morphology of nanocrystals at the atomic and single nanoparticle scales. To date, groups have quantitatively interpreted the mean growth rate of nanoparticles in terms of the Lifshitz-Slyozov-Wagner (LSW) model for Ostwald ripening, but less attention has been paid to modeling the corresponding particle size distribution. Here we use in situ fluid stage scanning TEM to demonstrate that silver nanoparticles grow by a length-scale dependent mechanism, where individual nanoparticles grow by monomer attachment but ensemble-scale growth is dominated by aggregation. Although our observed mean nanoparticle growth rate is consistent with the LSW model, we show that the corresponding particle size distribution is broader and more symmetric than predicted by LSW. Following direct observations of aggregation, we interpret the ensemble-scale growth using Smoluchowski kinetics and demonstrate that the Smoluchowski model quantitatively captures the mean growth rate and particle size distribution. PMID:24325680

Woehl, Taylor J; Park, Chiwoo; Evans, James E; Arslan, Ilke; Ristenpart, William D; Browning, Nigel D

2014-01-01

196

Statistical study of muons counts rates in differents directions, observed at the Brazilian Southern Space Observatory  

NASA Astrophysics Data System (ADS)

Cosmic ray are charged particles, at the most time protons, that reach the earth's magne-tosphere from interplanetary space with velocities greater than the solar wind. When these impinge the atmosphere, they interact with atmosphere constituents and decay into sub-particles forming an atmospheric shower. The muons are the sub-particles which normally maintain the originated direction of the primary cosmic ray. A multi-directional muon detec-tor (MMD) was installed in 2001 and upgraded in 2005, through an international cooperation between Brazil, Japan and USA, and operated since then at the Southern Space Observatory -SSO/CRS/CCR/INPE -MCT, (29,4° S, 53,8° W, 480m a.s.l.), São Martinho da Serra, RS, a Brazil. The main objetive of this work is to present a statistical analysis of the intensity of muons, with energy between 50 and 170 GeV, in differents directions, measured by the SSO's multi-directional muon detector. The analysis was performed with data from 2006 and 2007 collected by the SSO's MMD. The MMD consists of two layers of 4x7 detectors with a total observation area of 28 m2 . The counting of muons in each directional channel is made by a coincidence of pulses pair, one from a detector in the upper layer and the other from a detector in the lower layer. The SSO's MMD is equipped with 119 directional channels for muon count rate measurement and is capable of detecting muons incident with zenithal angle between 0° and 75,53° . A statistical analysis was made with the MMD muon count rate for all the di-rectional channels. The average and the standard deviation of the muon count rate in each directional component were calculated. The results show lower cont rate for the channels with larger zenith, and higher cont rate with smaller zenith, as expected from the production and propagation of muons in the atmosphere. It is also possible to identify the Stormer cone. The SSO's MMD is also a detector component of the Global Muon Detector Network (GMDN), which has been developed in an international collaboration lead by Shinshu University, Japan.

Grams, Guilherme; Schuch, Nelson Jorge; Braga, Carlos Roberto; Purushottam Kane, Rajaram; Echer, Ezequiel; Ronan Coelho Stekel, Tardelli

197

Airborne hyperspectral observations of surface and cloud directional reflectivity using a commercial digital camera  

NASA Astrophysics Data System (ADS)

Spectral radiance measurements by a digital single-lens reflex camera were used to derive the directional reflectivity of clouds and different surfaces in the Arctic. The camera has been calibrated radiometrically and spectrally to provide accurate radiance measurements with high angular resolution. A comparison with spectral radiance measurements with the Spectral Modular Airborne Radiation measurement sysTem (SMART-Albedometer) showed an agreement within the uncertainties of both instruments (6% for both). The directional reflectivity in terms of the hemispherical directional reflectance factor (HDRF) was obtained for sea ice, ice-free ocean and clouds. The sea ice, with an albedo of ? = 0.96 (at 530 nm wavelength), showed an almost isotropic HDRF, while sun glint was observed for the ocean HDRF (? = 0.12). For the cloud observations with ? = 0.62, the cloudbow - a backscatter feature typically for scattering by liquid water droplets - was covered by the camera. For measurements above heterogeneous stratocumulus clouds, the required number of images to obtain a mean HDRF that clearly exhibits the cloudbow has been estimated at about 50 images (10 min flight time). A representation of the HDRF as a function of the scattering angle only reduces the image number to about 10 (2 min flight time). The measured cloud and ocean HDRF have been compared to radiative transfer simulations. The ocean HDRF simulated with the observed surface wind speed of 9 m s-1 agreed best with the measurements. For the cloud HDRF, the best agreement was obtained by a broad and weak cloudbow simulated with a cloud droplet effective radius of Reff = 4 ?m. This value agrees with the particle sizes derived from in situ measurements and retrieved from the spectral radiance of the SMART-Albedometer.

Ehrlich, A.; Bierwirth, E.; Wendisch, M.; Herber, A.; Gayet, J.-F.

2012-04-01

198

Directivity of Solar Type III Radio Bursts: Multi-spacecraft Observations  

NASA Astrophysics Data System (ADS)

Simultaneous observations of solar type III radio bursts obtained by the STEREO A, B and WIND spacecraft at low frequencies from different vantage points in the ecliptic plane are used to determine their directivity. The heliolongitudes of the sources of these bursts, estimated at different frequencies by assuming that they are located on the Parker spiral magnetic field lines emerging from the associated active regions into the spherically symmetric solar atmosphere, and the heliolongitudes of the spacecraft are used to estimate the viewing angle, which is the angle between the direction of the magnetic field at the source and the line connecting the source to the spacecraft. The normalized peak intensities at each spacecraft R_j = {I_j}/{? I_j} (the subscript j corresponds to the spacecraft STEREO A, B and WIND), which are defined as the directivity factors are determined using the time profiles of the type III bursts. It is shown that the distribution of the viewing angles divides the type III bursts into: (1) bursts emitting into a very narrow cone centered around the tangent to the magnetic field with angular width of ˜ 2°, and (2) bursts emitting into a wider cone with angular width spanning from ˜ -100° to ˜ 100°. The plots of the directivity factors versus the viewing angles of the sources from all three spacecraft indicate that the type III emissions are very intense along the tangent to the spiral magnetic field lines at the source, and steadily fall as the viewing angles increase to higher values. The comparison of these emission patterns with the computed distributions of the ray trajectories indicate that the intense bursts visible in a narrow range of angles around the magnetic field directions probably are emitted in the fundamental mode, whereas the relatively weaker bursts visible to a wide range of angles are probably emitted in the harmonic mode.

Golla, Thejappa; Macdowall, Robert; Bergamo, Michael

2012-07-01

199

Can single electron effects be directly observed in Si quantum dots array at room temperature?  

Microsoft Academic Search

We report a direct observation of Coulomb blockade and quantum confinement effects in the room-temperature current-voltage (I-V) characteristics of Si quantum dots (Si-QDs) array (with a mean diameter of 6 nm), which is embedded in the SiO2\\/Si-QDs array\\/SiO2\\/n+-Si (100) structure and elaborated in a plasma enhanced chemical vapor deposition (PECVD) system by layer-by-layer technique and in situ plasma oxidation. The

L. W. Yu; K. J. Chen; L. C. Wu; M. Dai; W. Li; X. F. Huang

2004-01-01

200

Observation of intermediate template directed SiC nanowire growth in Si-C-N systems  

NASA Astrophysics Data System (ADS)

SiC nanowires (NWs) are commonly prepared in a Si-C-N system, but its formation mechanism is not fully understood. High resolution transmission electron microscopy and electron energy loss spectroscopy observation recorded the growth process of how Si3N4 NWs were transformed into SiC NWs, and demonstrated the validity of an intermediate template directed SiC NW growth via carbothermal reduction of intermediate Si3N4 NWs in a Si-C-N system. Based on this discovery, an intermediate-template growth mechanism of SiC NWs was proposed.

Xia, Min; Yang, Shize; Guo, Hongyan; Hao, Wei; Yan, Qingzhi; Ge, Changchun

2012-10-01

201

Observation of intermediate template directed SiC nanowire growth in Si-C-N systems.  

PubMed

SiC nanowires (NWs) are commonly prepared in a Si-C-N system, but its formation mechanism is not fully understood. High resolution transmission electron microscopy and electron energy loss spectroscopy observation recorded the growth process of how Si(3)N(4) NWs were transformed into SiC NWs, and demonstrated the validity of an intermediate template directed SiC NW growth via carbothermal reduction of intermediate Si(3)N(4) NWs in a Si-C-N system. Based on this discovery, an intermediate-template growth mechanism of SiC NWs was proposed. PMID:23018814

Xia, Min; Yang, Shize; Guo, Hongyan; Hao, Wei; Yan, Qingzhi; Ge, Changchun

2012-10-19

202

Direct observation of the quantum critical point in heavy fermion CeRhSi3.  

PubMed

We report on muon spin rotation studies of the noncentrosymmetric heavy fermion antiferromagnet CeRhSi3. A drastic and monotonic suppression of the internal fields, at the lowest measured temperature, was observed upon an increase of external pressure. Our data suggest that the ordered moments are gradually quenched with increasing pressure, in a manner different from the pressure dependence of the Néel temperature. At 23.6 kbar, the ordered magnetic moments are fully suppressed via a second-order phase transition, and T(N) is zero. Thus, we directly observed the quantum critical point at 23.6 kbar hidden inside the superconducting phase of CeRhSi3. PMID:22680903

Egetenmeyer, N; Gavilano, J L; Maisuradze, A; Gerber, S; MacLaughlin, D E; Seyfarth, G; Andreica, D; Desilets-Benoit, A; Bianchi, A D; Baines, Ch; Khasanov, R; Fisk, Z; Kenzelmann, M

2012-04-27

203

On the Contextual Independence of Personality: Teachers' Assessments Predict Directly Observed Behavior after Four Decades  

PubMed Central

The continuity of personality’s association with directly observed behavior is demonstrated across two contexts spanning four decades. During the 1960s, elementary school teachers rated personalities of members of the ethnically diverse Hawaii Personality and Health Cohort (Hampson & Goldberg, 2006). The same individuals were interviewed in a medical clinic over 40 years later. Trained coders viewed video recordings of a subset of these interviews (N = 144, 68 F, 76 M) and assessed the behavior they observed using the Riverside Behavioral Q-sort Version 3.0 (Funder, Furr & Colvin, 2000; Furr, Wagerman & Funder, 2010). Children rated by their teachers as “verbally fluent” (defined as unrestrained talkativeness) showed dominant and socially adept behavior as middle-aged adults. Early “adaptability” was associated with cheerful and intellectually curious behavior, early “impulsivity” was associated with later talkativeness and loud speech, and early rated tendencies to “self-minimize” were related to adult expressions of insecurity and humility.

Nave, Christopher S.; Sherman, Ryne A.; Funder, David C.; Hampson, Sarah E.; Goldberg, Lewis R.

2010-01-01

204

Direct observation of stochastic domain-wall depinning in magnetic nanowires  

SciTech Connect

The stochastic field-driven depinning of a domain wall pinned at a notch in a magnetic nanowire is directly observed using magnetic X-ray microscopy with high lateral resolution down to 15 nm. The depinning-field distribution in Ni{sub 80}Fe{sub 20} nanowires considerably depends on the wire width and the notch depth. The difference in the multiplicity of domain-wall types generated in the vicinity of a notch is responsible for the observed dependence of the stochastic nature of the domain wall depinning field on the wire width and the notch depth. Thus the random nature of the domain wall depinning process is controllable by an appropriate design of the nanowire.

Im, Mi-Young; Bocklage, Lars; Fischer, Peter; Meier, Guido

2008-11-01

205

Direct observation of two protons in the decay of 54Zn.  

PubMed

The two protons emitted in the decay of 54Zn have been individually observed for the first time in a time projection chamber. The total decay energy and the half-life measured in this work agree with the results obtained in a previous experiment. Angular and energy correlations between the two protons are determined and compared to theoretical distributions of a three-body model. Within the shell model framework, the relative decay probabilities show a strong contribution of the p2 configuration for the two-proton emission. After 45Fe, the present result on 54Zn constitutes only the second case of a direct observation of the ground state two-proton decay of a long-lived isotope. PMID:21981498

Ascher, P; Audirac, L; Adimi, N; Blank, B; Borcea, C; Brown, B A; Companis, I; Delalee, F; Demonchy, C E; de Oliveira Santos, F; Giovinazzo, J; Grévy, S; Grigorenko, L V; Kurtukian-Nieto, T; Leblanc, S; Pedroza, J-L; Perrot, L; Pibernat, J; Serani, L; Srivastava, P C; Thomas, J-C

2011-09-01

206

Direct torque control with an optimized observer for multi-machine systems  

NASA Astrophysics Data System (ADS)

The first purpose of this work is to design a new observation technique for the Direct Torque Control (DTC). We put emphasis on robustness especially at very low speed, which represents the basic problem of the DTC operating, and on the optimization of the time computing. The reduced order observer is defined by decoupling the full order one in ? and ? axis. The second basic aim of this paper is to apply the DTC strategy to multi-machine multi-inverter industrial systems. Speed and tension controls are designed; their performances and parameter robustness are analyzed and compared with those obtained with a Flux Oriented Control (FOC). Mechanical and electrical couplings constitute the principal operation difficulty of these systems mainly when one of the machines is perturbed.

Belhadj, J.; Belkhodja, I. S.; David, M.; de Fornel, B.

2006-01-01

207

Direct time resolved observation of molecular dynamics induced by soft-x-ray photoionization  

NASA Astrophysics Data System (ADS)

We report the first direct observation of ultrafast dynamics in molecules induced by ionizing radiation. We use high harmonic upconversion process to generate soft-x-ray pulses of few femtoseconds duration, which photoionize N2 molecule. This leads to the formation of highly excited N2+ ions via inner-shell ionization and electron shakeup processes. We time resolve the unexplored fragmentation dynamics of the electron shakeup states with femtosecond resolution using a strong-field IR probe. The IR pulse promotes the dissociating N2+ wavepacket to repulsive N22+ potential. We obtain kinetic energy release of N+/N+ channel as function of time delay and observe a rapid transition from spherically-symmetric molecular potential to a two-center potential within ~150 fs.

Sandhu, A. S.; Gagnon, E.; Ranitovic, P.; Tong, X.-M.; Cocke, C. L.; Murnane, M. M.; Kapteyn, H. C.

2007-11-01

208

Direct observation of Dirac cones and a flatband in a honeycomb lattice for polaritons.  

PubMed

Two-dimensional lattices of coupled micropillars etched in a planar semiconductor microcavity offer a workbench to engineer the band structure of polaritons. We report experimental studies of honeycomb lattices where the polariton low-energy dispersion is analogous to that of electrons in graphene. Using energy-resolved photoluminescence, we directly observe Dirac cones, around which the dynamics of polaritons is described by the Dirac equation for massless particles. At higher energies, we observe p orbital bands, one of them with the nondispersive character of a flatband. The realization of this structure which holds massless, massive, and infinitely massive particles opens the route towards studies of the interplay of dispersion, interactions, and frustration in a novel and controlled environment. PMID:24702392

Jacqmin, T; Carusotto, I; Sagnes, I; Abbarchi, M; Solnyshkov, D D; Malpuech, G; Galopin, E; Lemaître, A; Bloch, J; Amo, A

2014-03-21

209

Direct in Situ Observation of Nanoparticle Synthesis in a Liquid Crystal Surfactant Template  

SciTech Connect

Controlled synthesis of nanostructures is essential for many applications, from energy storage/generation and catalysis to semiconductor and biomedical devices. Normally, nanostructures are characterized after synthesis and growth mechanisms are assumed. Here we show the first direct observation of nanoparticle synthesis in a liquid crystal surfactant template using an electron microscope fluid stage. The nanoparticles first sinter (to ~5nm), then grow connections to each other around the micelles to form clusters. Upon reaching a critical size (>10-15nm), the clusters become highly mobile in the template, displacing micelles to form spherical nanoparticles. This ability to observe and understand fundamental growth mechanisms on the nanoscale in real time and in aqueous environments will impact every branch of nanoscience where precise control over nanostructure is essential. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

Parent, Lucas R.; Robinson, David R.; Woehl, Taylor J.; Ristenpart, William D.; Evans, James E.; Browning, Nigel D.; Arslan, Ilke

2012-04-24

210

Direct observation of frictional contacts: New insights for state-dependent properties  

USGS Publications Warehouse

Rocks and many other materials display a rather complicated, but characteristic, dependence of friction on sliding history. These effects are well-described by empirical rate- and state-dependent constitutive formulations which have been utilized for analysis of fault slip and earthquake processes. We present a procedure for direct quantitative microscopic observation of frictional contacts during slip. The observations reveal that frictional state dependence represents an increase of contact area with contact age. Transient changes of sliding resistance correlate with changes in contact area and arise from shifts of contact population age. Displacement-dependent replacement of contact populations is shown to cause the diagnostic evolution of friction over a characteristic sliding distance that occurs whenever slip begins or sliding conditions change. ?? 1994 Birkha??user Verlag.

Dieterich, J. H.; Kilgore, B. D.

1994-01-01

211

New direction in the development of the observation software framework (BOSS)  

NASA Astrophysics Data System (ADS)

The Observation Software (OS) of astronomical instruments, which lie directly beneath the instructions of astronomers, carrying out exposures and calibrations is the supervisor of the multi-process and multi-layer instrument software package. The main responsibility of the OS is the synchronization of the subsystems (detectors and groups of mechanical devices) and the telescope during exposures. At ESO a software framework Base Observation Software Stub (BOSS) takes care of the common functionalities of all OS of various instruments at the various sites VLT, VLTI, La Silla and Vista. This paper discusses the latest applications and how their new generic requirements contributes to the BOSS framework. The paper discusses the resolution of problems of event queues, interdependent functionalities, parallel commands and asynchronous messages in the OS using OO technologies.

Pozna, Eszter; Smette, Alain; Schmutzer, Ricardo; Abuter, Roberto; Duc, Thanh Phan; Santin, Paolo

2010-07-01

212

Direct Observation of Two Protons in the Decay of {sup 54}Zn  

SciTech Connect

The two protons emitted in the decay of {sup 54}Zn have been individually observed for the first time in a time projection chamber. The total decay energy and the half-life measured in this work agree with the results obtained in a previous experiment. Angular and energy correlations between the two protons are determined and compared to theoretical distributions of a three-body model. Within the shell model framework, the relative decay probabilities show a strong contribution of the p{sup 2} configuration for the two-proton emission. After {sup 45}Fe, the present result on {sup 54}Zn constitutes only the second case of a direct observation of the ground state two-proton decay of a long-lived isotope.

Ascher, P.; Audirac, L.; Blank, B.; Delalee, F.; Demonchy, C. E.; Giovinazzo, J.; Grevy, S.; Kurtukian-Nieto, T.; Leblanc, S.; Pedroza, J.-L.; Pibernat, J.; Serani, L. [Centre d'Etudes Nucleaires de Bordeaux Gradignan--Universite Bordeaux 1--UMR 5797 CNRS/IN2P3, Chemin du Solarium, BP 120, 33175 Gradignan (France); Adimi, N. [Centre d'Etudes Nucleaires de Bordeaux Gradignan--Universite Bordeaux 1--UMR 5797 CNRS/IN2P3, Chemin du Solarium, BP 120, 33175 Gradignan (France); Faculte de Physique, USTHB, B.P.32, El Alia, 16111 Bab Ezzouar, Alger (Algeria); Borcea, C.; Companis, I. [National Institute for Physics and Nuclear Engineering, P.O. Box MG6, Bucharest-Margurele (Romania); Brown, B. A. [Department of Physics and Astronomy, and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824-1321 (United States); Oliveira Santos, F. de; Perrot, L.; Thomas, J.-C. [Grand Accelerateur National d'Ions Lourds, CEA/DSM-CNRS/IN2P3, 14076 Caen Cedex 05 (France); Grigorenko, L. V. [Flerov Laboratory of Nuclear Reactions, JINR, Dubna 141980 (Russian Federation)

2011-09-02

213

Acidification of the North Pacific Ocean: Direct Observations of pH in 1991 and 2006  

NASA Astrophysics Data System (ADS)

Spectrophotometric procedures were first successfully used to obtain seawater pH profiles on a 1991 cruise within the CLIVAR/CO2 Repeat Hydrography Program. During a 2006 reoccupation of the P16N transect along 152 ^{0}W, closely similar methods were used to obtain a fifteen-year spectrophotometrically-based record of ocean pH change. Spectrophotometric procedures are particularly robust as a means of observing changes in seawater pH because sulfonephthalein equilibrium constants, being nearly constant at constant temperature and salinity, are unimportant in pH difference calculations. In such cases, the quality of pH difference measurements is most closely related to measurement precision. Since the precision of spectrophotometric pH measurements (using observations of sulfonephthalein absorbance ratios) is on the order of 0.0004 pH units, pH differences can be measured with a precision somewhat better than +/- 0.001. In the absence of other effects, the atmospheric pCO2 increase between 1991 and 2006 would decrease the pH of the surface ocean, in equilibrium with the atmosphere, by approximately 0.025 pH units. Thus, spectrophotometric pH observations are capable of directly resolving pH perturbations on a scale commensurate with potential atmospherically-induced changes. At depths between 3000 and 5000 meters the directly observed mean fifteen-year pH difference was on the order of 0.000 +/-0.0015. At depths below 1000 meters, pH changes generally ranged between + 0.006 and -0.006. In contrast, in the upper 700 meters, pH was much more variable, with an average fifteen-year pH decrease on the order of 0.025 and including pH differences as large as -0.055. These directly observed pH differences are consistent with expected changes in response to elevated atmospheric CO2, along with changes that can be attributed to differences in respiration and changes in ocean circulation.

Byrne, R. H.; Liu, X.; Mecking, S.; Feely, R. A.

2006-12-01

214

Direct observation of one-dimensional diffusion and transcription by Escherichia coli RNA polymerase.  

PubMed Central

The dynamics of nonspecific and specific Escherichia coli RNA polymerase (RNAP)-DNA complexes have been directly observed using scanning force microscopy operating in buffer. To this end, imaging conditions had to be found in which DNA molecules were adsorbed onto mica strongly enough to be imaged, but loosely enough to be able to diffuse on the surface. In sequential images of nonspecific complexes, RNAP was seen to slide along DNA, performing a one-dimensional random walk. Heparin, a substance known to disrupt nonspecific RNAP-DNA interactions, prevented sliding. These observations suggest that diffusion of RNAP along DNA constitutes a mechanism for accelerated promoter location. Sequential images of single, transcribing RNAP molecules were also investigated. Upon addition of 5 microM nucleoside triphosphates to stalled elongation complexes in the liquid chamber, RNAP molecules were seen to processively thread their template at rates of 1.5 nucleotide/s in a direction consistent with the promoter orientation. Transcription assays, performed with radiolabeled, mica-bound transcription complexes, confirmed this rate, which was about three times smaller than the rate of complexes in solution. This assay also showed that the pattern of pause sites and the termination site were affected by the surface. By using the Einstein-Sutherland friction-diffusion relation the loading force experienced by RNAP due to DNA-surface friction is estimated and discussed.

Guthold, M; Zhu, X; Rivetti, C; Yang, G; Thomson, N H; Kasas, S; Hansma, H G; Smith, B; Hansma, P K; Bustamante, C

1999-01-01

215

The Exozodiacal Dust Problem for Direct Observations of ExoEarths  

NASA Technical Reports Server (NTRS)

Debris dust in the habitable zones of stars otherwise known as exozodiacal dust comes from extrasolar asteroids and comets and is thus an expected part of a planetary system. Background flux from the Solar Systems zodiacal dust and the exozodiacal dust in the target system is likely to be the largest source of astrophysical noise in direct observations of terrestrial planets in the habitable zones of nearby stars. Furthermore, dust structures like clumps, thought to be produced by dynamical interactions with exoplanets, are a possible source of confusion. In this paper, we qualitatively assess the primary impact of exozodical dust on high-contrast direct imaging at optical wavelengths, such as would be performed with a coronagraph. Then we present the sensitivity of previous, current, and near-term facilities to thermal emission from debris dust at all distances from nearby solar-type stars, as well as our current knowledge of dust levels from recent surveys. Finally, we address the other method of detecting debris dust, through high-contrast imaging in scattered light. This method is currently far less sensitive than thermal emission observations, but provides high spatial resolution for studying dust structures. This paper represents the first report of NASA's Exoplanet Exploration Program Analysis Group (ExoPAG).

Roberge, Aki; Chen, Christine H.; Millan-Gabet, Rafael; Weinberger, Alycia J.; Hinz, Philip M.; Stapelfeldt, Karl R.; Absil, Olivier; Kuchner, Marc J.; Bryden, Geoffrey

2012-01-01

216

Direct observation of pentacene-thiol interaction using x-ray spectroscopy  

NASA Astrophysics Data System (ADS)

There has been an intense interest in the surface modification of the source-drain electrodes for organic field effect transistors (OFETs) to improve their performance. A number of thiol based self assembled monolayers demonstrated improvements to the contact resistance and channel performance. Morphological improvements at the contacts, a change in the effective work function, and charge transfer between the thiols and the semiconductor have all been credited with the observed performance improvements. Using in-situ semiconductor deposition together with x-ray photoelectron spectroscopy and near-edge x-ray absorption fine structure, we are able to directly probe two technologically relevant OFET stacks. This work directly measures the interaction between pentacene and two thiols which have been associated to contact improvement: an electroneutral thiol (1-hexadecanethiol) and an electronegative thiol (pentafluorobenzenethiol). Based on our results we observe no chemical interaction between pentacene and the thiol. The electrical improvements to transistor performance, based on these systems, can be attributed to work function shifts of the contacts and morphological improvements of the organic semiconductor.

Jia, Zhang; Lee, Vincent; Floreano, Luca; Verdini, Alberto; Cossaro, Albano; Morgante, Alberto; Kymissis, Ioannis

2010-03-01

217

Direct observation of the superfluid phase transition in ultracold Fermi gases.  

PubMed

Phase transitions are dramatic phenomena: water freezes into ice, atomic spins spontaneously align in a magnet, and liquid helium becomes superfluid. Sometimes, such a drastic change in behaviour is accompanied by a visible change in appearance. The hallmark of Bose-Einstein condensation and superfluidity in trapped, weakly interacting Bose gases is the sudden formation of a dense central core inside a thermal cloud. However, in strongly interacting gases--such as the recently observed fermionic superfluids--there is no longer a clear separation between the superfluid and the normal parts of the cloud. The detection of fermion pair condensates has required magnetic field sweeps into the weakly interacting regime, and the quantitative description of these sweeps presents a major theoretical challenge. Here we report the direct observation of the superfluid phase transition in a strongly interacting gas of 6Li fermions, through sudden changes in the shape of the clouds--in complete analogy to the case of weakly interacting Bose gases. By preparing unequal mixtures of the two spin components involved in the pairing, we greatly enhance the contrast between the superfluid core and the normal component. Furthermore, the distribution of non-interacting excess atoms serves as a direct and reliable thermometer. Even in the normal state, strong interactions significantly deform the density profile of the majority spin component. We show that it is these interactions that drive the normal-to-superfluid transition at the critical population imbalance of 70 +/- 5 per cent (ref. 12). PMID:16823447

Zwierlein, Martin W; Schunck, Christian H; Schirotzek, André; Ketterle, Wolfgang

2006-07-01

218

Direct observation of the ice rule in demagnetized artificial kagome spin ice  

NASA Astrophysics Data System (ADS)

Artificially designed magnetic structures have proven to be good analogs for the study of spin ice. We studied an artificial kagome spin ice, which is lithographically patterned using permalloy elements ˜23nm thick, ˜100nm wide, and ˜500nm long. Lorentz TEM is used to unambiguously determine each local pseudospin. Even with a rigorous randomizing demagnetization process, we directly observe an exclusive ice rule and ice-like short range correlations. This is the first time that the ice rule has been confirmed by direct counting of the nearest-neighbors in any ice system, real or artificial. The further-neighbor correlations we observe are larger in magnitude than predicted for a random ice-rule ensemble, and we attribute this to the effects of dipolar interactions. Further, we investigate the entropy associated with artificial kagome spin ice based on the general concept of Shannon entropy [1]. These results will be presented and compared with relevant theoretical studies. [1] C.E. Shannon, Bell System Technical Journal, 27, 379 (1948)

Qi, Yi; Brintlinger, Todd; Cumings, John; Mellado, Paula; Tchernyshyov, Oleg

2008-03-01

219

Direct observation of transient states in nanolaminates using nanosecond in situ TEM  

NASA Astrophysics Data System (ADS)

The microstructure and properties of a material depend on dynamic processes such as defect motion, nucleation and growth, and phase transitions, which commonly occur on the nanosecond to microsecond timescale. Modern in situ transmission electron microscopy (TEM) can spatially resolve these nanoscale phenomena but lacks the time resolution to observe the processes directly. The Dynamic TEM (DTEM) has been developed to address this gap in characterization capability by using a short photoemitted electron pulse to probe dynamic events with "snap-shot" diffraction and imaging with 15-nanosecond resolution. This fast in situ capability is highlighted here in a study of Al/Ni reactive multilayer foils (RMLF), which are used as localized heat sources for joining in microelectronics and as rapid fuses. The layered foil geometry contains many interfaces where the atoms can mix to react with each other, forming intermetallic compounds. Once the reaction is initiated by a laser, the formation reaction releases more heat and becomes self-sustaining as it propagates through the remaining material at ˜10 m/s. This dynamic mixing reaction is referred to as self-propagating high-temperature synthesis (SHS). The reaction front velocity and nanoscale geometry make direct observation of the reaction front impossible by any other existing technique. This work describes direct observations of single-pulse nanosecond scale TEM data in both diffraction and imaging modes, which are necessary to study the propagation and behavior of energetic nanolaminates in situ. The pulsed electron interrogation method reveals that transient morphologies are produced and attributed to a brief phase separation during the SHS. The features appear as lines of mass-thickness contrast due to cellular phase formation of liquid and an ordered B2 NiAl phase. At high formation temperatures of ˜1700 K, these materials are now known to exhibit transverse self-ordering. It is significant and exciting to find spontaneous, rapid formation of ordered structures in materials far from equilibrium, which is also an important step for essential comprehension of RMLF performance in applications. These observations provide insight into the mechanisms driving the dynamic process and give perspective on the application of the DTEM technique to other materials.

Kim, Judy Sooyean

220

Direct Observation of Enzymes Replicating DNA Using a Single-molecule DNA Stretching Assay  

PubMed Central

We describe a method for observing real time replication of individual DNA molecules mediated by proteins of the bacteriophage replication system. Linearized ? DNA is modified to have a biotin on the end of one strand, and a digoxigenin moiety on the other end of the same strand. The biotinylated end is attached to a functionalized glass coverslip and the digoxigeninated end to a small bead. The assembly of these DNA-bead tethers on the surface of a flow cell allows a laminar flow to be applied to exert a drag force on the bead. As a result, the DNA is stretched close to and parallel to the surface of the coverslip at a force that is determined by the flow rate (Figure 1). The length of the DNA is measured by monitoring the position of the bead. Length differences between single- and double-stranded DNA are utilized to obtain real-time information on the activity of the replication proteins at the fork. Measuring the position of the bead allows precise determination of the rates and processivities of DNA unwinding and polymerization (Figure 2).

Kulczyk, Arkadiusz W.; Tanner, Nathan A.; Loparo, Joseph J.; Richardson, Charles C.; van Oijen, Antoine M.

2010-01-01

221

Shallow vent architecture of Puyehue Cordón-Caulle, as revealed by direct observation of explosive activity  

NASA Astrophysics Data System (ADS)

On June 4, 2011, an explosive eruption of rhyodacitic magma began at the Puyehue Cordón-Caulle volcanic complex (PCCVC), southern Chile. Initial Plinian phases of the eruption produced tephra plumes reaching > 14 km high, the ash from which quickly circumnavigated the globe to cause widespread disruption to air traffic in the Southern Hemisphere. Within two weeks, the continuing explosive eruption was joined by synchronous effusion of lava. We present observations of complex vent activity made 7 months after the eruption onset, on January 4th and 10th, 2012, when explosive activity from PCCVC continued at a lower level of intensity. Fortuitous climatic conditions permitted direct, ground-based observation and video recording of transient vent dynamics within the asymmetrical tephra cone around the main eruptive vent complex and site of lava effusion, as well as real-time collection of juvenile ash as it rained out directly from the active plume. On Jan. 4, explosive activity was semi-continuous ash jetting punctuated by Vulcanian-like blasts. In the ~50m-diameter sub-circular base of the ~400 m-wide, asymmetrical tephra cone, near-continuous ash jetting was observed from two primary point sources. The northerly source was clearly visible, with time-averaged diameter of ~10 m, and the apparently larger southerly source was mostly obscured from view by the ash plume. Activity was at all times somewhat erratic, but followed a rough cyclicity on 30-45 s timescales, consisting of: (1) restriction of the point source into a focused ash jet up to ~50 m high, producing coarse ash dominated by tube pumice (with minor free pyroxene crystals); followed by (2) Vulcanian-like failure of the region around the point source, producing incandescent ballistic bombs thrown up to 100-200 m from the vent. Jetting from the two main point sources combined in the crater to produce a low gas-thrust region and sustained buoyant plume. Directed ash plumes that climbed and breached the inner wall of the tephra cone were entrained upward into the main vertical portion of the plume. On Jan. 10, explosive activity was manifested as semi-continuous ash jetting from multiple point sources, as accommodated by a 10-20 m high incipient dome that had formed in the tephra cone. At any given time, up to 10 discrete point and linear sources of gas and ash discharge could be seen. These had variable directionality and produced plumes with spatially and temporally variable ash contents. Cycles of overpressure buildup and vent failure were still observed, but rarely produced significant bombs. Instead, failure was characterized by the simultaneous or staggered opening of many additional point discharge sources, often defining a dish-like structure around - but not disturbing - the incipient dome. During this lower-intensity activity, no defined gas-thrust region was maintained and the plume would often collapse to fill the tephra cone. Directed plumes that breached the cone continued to descend its outer slopes. Ongoing analysis of juvenile pyroclasts and video footage permits an assessment of overpressure buildup and release in the shallow conduit of the PCCVC, and an assessment of the complex shallow vent architecture. We address the ideas: (1) that to describe explosive ash jetting from a single "vent" is a gross oversimplification of what is actually a highly transient, multiple point-source vent complex subject to variations in permeability and rate/type of discharge; and (2) that gas and ash jetting and Vulcanian blasts play an important if not necessary role in generating degassed magma that erupts effusively (see Castro et al., this session).

Schipper, C. I.; Tuffen, H.; Castro, J. M.

2012-04-01

222

Evaluation of flow direction methods against field observations of overland flow dispersion  

NASA Astrophysics Data System (ADS)

Despite the broad effort made in grid-based distributed catchment modeling to account for planar overland flow dispersion, actual dispersion experienced by overland flow along a natural slope has not been measured so far, and the ability of terrain analysis methods to reproduce this dispersion has not been evaluated. In the present study, the D8, D8-LTD, D? -LTD, D? , MD? , and MD8 flow direction methods are evaluated against field observations of overland flow dispersion obtained from novel experimental methods. Thin flows of cold (2--10oC) water were released at selected points on a warmer (15--30oC) slope and individual overland flow patterns originating from each of these points were observed using a terrestrial laser scanner and a thermal imaging camera. Prior to each experimental water release, a ScanStation C10 terrestrial laser scanner by Leica Geosystems was used to acquire a point cloud having average density of 25~points/cm2. This point cloud was used to generate alternative grid-based digital elevation models having resolution h ranging from 1~cm to 2~m. During the experiments, an Avio Advanced Thermo TVS-500EX camera by Nippon Avionics was used to monitor land surface temperature with resolution better than 0.05oC. The overland flow patterns were also found to be discernible in terrestrial laser scanner reflectance signal acquired immediately following the flow experiments. Overland flow patterns were determined by considering contrasted temperature and reflectance of the dry and wetted land surface portions. Predicted propagation patterns and observed flow patterns were compared by considering the fractions of flow released at the point source that propagates through the grid cells. Predictions of these quantities were directly provided by flow direction methods and by related flow accumulation algorithms. Suitable data for the comparison were derived from observed overland flow patterns by assuming a uniform distribution of flow along each cross section. Planar overland flow dispersion is found to play an important role in the region lying immediately downslope of the point source, but attenuates rapidly as flow propagates downslope displaying a nearly constant width of about 50~cm. In contrast, existing dispersive flow direction methods are found to provide a continued dispersion with distance downslope. Predicted propagation patterns, for all methods considered here, depend critically on h. All methods are found to be poorly sensitive in extremely fine grids (h ? 2~cm), and to be poorly specific in coarse grids (h = 2~m). Satisfactory results are, however, obtained when h approaches the average flow width, with the best performances in terms of Pearson correlation coefficient displayed by the MD8 method in the finest grids (5~cm ? h ? 20~cm), and by the MD? , D? , and D? -LTD methods in the coarsest grids (20~cm < h ? 1~m). The results obtained in this study suggest further testing of terrain analysis methods with longer flow patterns and coarser grids. Scale issues affecting the relation between land surface microtopography, dispersion, and size of grid cells involved need then to be addressed to provide a hydrologic model of flow partitioning along the slope directions identified by terrain analysis methods.

Orlandini, S.; Moretti, G.; Corticelli, M. A.; Santangelo, P. E.; Capra, A.; Rivola, R.; Albertson, J. D.

2012-12-01

223

Comparison of cost effectiveness of directly observed treatment (DOT) and conventionally delivered treatment for tuberculosis: experience from rural South Africa  

Microsoft Academic Search

AbstractObjective: To conduct an economic evaluation of directly observed treatment (DOT) and conventionally delivered treatment for the management of new cases of tuberculosis in adults.Design: Community based directly observed treatment, which has been implemented in the Hlabisa district of South Africa since 1991, was compared with a conventional approach to tuberculosis treatment widely used in Africa. Each was assessed in

Katherine Floyd; David Wilkinson; Charles Gilks

1997-01-01

224

Direct observations of the influence of solution composition on magnesite dissolution  

NASA Astrophysics Data System (ADS)

In situ observations during atomic force microscopy experiments and ex situ observations after static and flow-through experiments were used to explore the effect of three different electrolytes on magnesite (MgCO3) dissolution at pH 2. The experiments showed that the magnesite dissolution rate varied in the order NO3->Cl>SO42- when these anions were present in solution. Under the experimental conditions magnesite dissolution occurred via the removal of successive single surface layers, where changes in magnesite reactivity in the presence of different electrolytes could be observed as variations in the cycle length for the removal of one unit cell layer. The cycles began with the formation of sporadically distributed etch pits followed by the nucleation of homogeneously distributed etch pits. Coalescence of the etch pits formed isolated sections of the remnant surface, which then dissolved away. The timing of sporadic and homogeneous etch pit nucleation was constant despite the presence of different anions. However, the cycles in surface roughness and etch pit spreading rates indicate that the different anions affect step retreat rates and hence dissolution rates. Differences in magnesite reactivity can be attributed to the direct interaction of sulphate with the magnesite surface and the indirect effects of chloride and nitrate on the magnesite surface hydration and hydration of the Mg2+ ion in solution. In all experiments during the dissolution process evidence for the precipitation of a new phase was observed, either directly as precipitates forming on the magnesite surface in the AFM and after the experiments, seen in SEM analysis, or as changes in the Mg outlet concentration during flow-through experiments. EDX and Raman spectroscopy were used to analyse the composition of the precipitate and although it could not be definitively identified, considering previous observations the precipitate is most likely a hydrated Mg-carbonate phase with a MgCO3·xH2O composition. Thus, the formation of a precipitate can facilitate further magnesite dissolution by increasing the undersaturation of the interfacial solution.

King, Helen E.; Putnis, Christine V.

2013-05-01

225

A new filter for the Mean Dynamic Topography of the ocean derived directly from satellite observations  

NASA Astrophysics Data System (ADS)

The Mean Dynamic Topography (MDT) of the ocean provides valuable information about the ocean's surface currents. Therefore the MDT is computed from satellite observations and then assimilated into ocean models in order to improve the ocean circulation estimates. However, the computation of the MDT from satellite observations of sea surface height and the Earth's gravity field is not straightforward and requires additional filtering of the data combination. The choice of the filter is crucial as it determines the amount of small-scale noise in the data and the resolution of the final MDT. There exist various approaches for the determination of an "optimal" filter. However, they all have in common the more or less subjective choice of the filter type and filter width. Here, a new filter is presented that is determined directly from the geodetic normal equations. By its construction, this filter accurately accounts for the correlations within the MDT data and requires no subjective choice about the filter radius. The new filtered MDT is assimilated into an inverse ocean model. Modifications in the meridional overturning circulation and in the poleward heat transports can be observed, compared to the result of the assimilation using the unfiltered MDT.

Freiwald, G.

2013-12-01

226

Direct observation of microcavitation in underwater adhesion of mushroom-shaped adhesive microstructure  

PubMed Central

Summary In this work we report on experiments aimed at testing the cavitation hypothesis [Varenberg, M.; Gorb, S. J. R. Soc., Interface 2008, 5, 383–385] proposed to explain the strong underwater adhesion of mushroom-shaped adhesive microstructures (MSAMSs). For this purpose, we measured the pull-off forces of individual MSAMSs by detaching them from a glass substrate under different wetting conditions and simultaneously video recording the detachment behavior at very high temporal resolution (54,000–100,000 fps). Although microcavitation was observed during the detachment of individual MSAMSs, which was a consequence of water inclusions present at the glass–MSAMS contact interface subjected to negative pressure (tension), the pull-off forces were consistently lower, around 50%, of those measured under ambient conditions. This result supports the assumption that the recently observed strong underwater adhesion of MSAMS is due to an air layer between individual MSAMSs [Kizilkan, E.; Heepe, L.; Gorb, S. N. Underwater adhesion of mushroom-shaped adhesive microstructure: An air-entrapment effect. In Biological and biomimetic adhesives: Challenges and opportunities; Santos, R.; Aldred, N.; Gorb, S. N.; Flammang, P., Eds.; The Royal Society of Chemistry: Cambridge, U.K., 2013; pp 65–71] rather than by cavitation. These results obtained due to the high-speed visualisation of the contact behavior at nanoscale-confined interfaces allow for a microscopic understanding of the underwater adhesion of MSAMSs and may aid in further development of artificial adhesive microstructures for applications in predominantly liquid environments.

Kovalev, Alexander E; Gorb, Stanislav N

2014-01-01

227

Direct observation of microcavitation in underwater adhesion of mushroom-shaped adhesive microstructure.  

PubMed

In this work we report on experiments aimed at testing the cavitation hypothesis [Varenberg, M.; Gorb, S. J. R. Soc., Interface 2008, 5, 383-385] proposed to explain the strong underwater adhesion of mushroom-shaped adhesive microstructures (MSAMSs). For this purpose, we measured the pull-off forces of individual MSAMSs by detaching them from a glass substrate under different wetting conditions and simultaneously video recording the detachment behavior at very high temporal resolution (54,000-100,000 fps). Although microcavitation was observed during the detachment of individual MSAMSs, which was a consequence of water inclusions present at the glass-MSAMS contact interface subjected to negative pressure (tension), the pull-off forces were consistently lower, around 50%, of those measured under ambient conditions. This result supports the assumption that the recently observed strong underwater adhesion of MSAMS is due to an air layer between individual MSAMSs [Kizilkan, E.; Heepe, L.; Gorb, S. N. Underwater adhesion of mushroom-shaped adhesive microstructure: An air-entrapment effect. In Biological and biomimetic adhesives: Challenges and opportunities; Santos, R.; Aldred, N.; Gorb, S. N.; Flammang, P., Eds.; The Royal Society of Chemistry: Cambridge, U.K., 2013; pp 65-71] rather than by cavitation. These results obtained due to the high-speed visualisation of the contact behavior at nanoscale-confined interfaces allow for a microscopic understanding of the underwater adhesion of MSAMSs and may aid in further development of artificial adhesive microstructures for applications in predominantly liquid environments. PMID:24991528

Heepe, Lars; Kovalev, Alexander E; Gorb, Stanislav N

2014-01-01

228

Direct observation of half-metallicity in the Heusler compound Co2MnSi  

PubMed Central

Ferromagnetic thin films of Heusler compounds are highly relevant for spintronic applications owing to their predicted half-metallicity, that is, 100% spin polarization at the Fermi energy. However, experimental evidence for this property is scarce. Here we investigate epitaxial thin films of the compound Co2MnSi in situ by ultraviolet-photoemission spectroscopy, taking advantage of a novel multi-channel spin filter. By this surface sensitive method, an exceptionally large spin polarization of () % at room temperature is observed directly. As a more bulk sensitive method, additional ex situ spin-integrated high energy X-ray photoemission spectroscopy experiments are performed. All experimental results are compared with advanced band structure and photoemission calculations which include surface effects. Excellent agreement is obtained with calculations, which show a highly spin polarized bulk-like surface resonance ingrained in a half metallic bulk band structure.

Jourdan, M.; Minar, J.; Braun, J.; Kronenberg, A.; Chadov, S.; Balke, B.; Gloskovskii, A.; Kolbe, M.; Elmers, H.J.; Schonhense, G.; Ebert, H.; Felser, C.; Klaui, M.

2014-01-01

229

Direct Observation of Single DNA Structural Alterations at Low Forces with Surface-Enhanced Raman Scattering  

PubMed Central

DNA experiences numerous mechanical events, necessitating single-molecule force spectroscopy techniques to provide insight into DNA mechanics as a whole system. Inherent Brownian motion limits current force spectroscopy methods from observing possible bond level structural changes. We combine optical trapping and surface-enhanced Raman scattering to establish a direct relationship between DNA’s extension and structure in the low force, entropic regime. A DNA molecule is trapped close to a surface-enhanced Raman scattering substrate to facilitate a detectable Raman signal. DNA Raman modes shift in response to applied force, indicating phosphodiester mechanical alterations. Molecular dynamic simulations confirm the local structural alterations and the Raman sensitive band identified experimentally. The combined Raman and force spectroscopy technique, to our knowledge, is a novel methodology that can be generalized to all single-molecule studies.

Rao, Satish; Raj, Saurabh; Cossins, Benjamin; Marro, Monica; Guallar, Victor; Petrov, Dmitri

2013-01-01

230

Direct observation of hierarchical nucleation of martensite and size-dependent superelasticity in shape memory alloys.  

PubMed

Martensitic transformation usually creates hierarchical internal structures beyond mere change of the atomic crystal structure. Multi-stage nucleation is thus required, where nucleation (level-1) of the underlying atomic crystal lattice does not have to be immediately followed by the nucleation of higher-order superstructures (level-2 and above), such as polysynthetic laths. Using in situ transmission electron microscopy (TEM), we directly observe the nucleation of the level-2 superstructure in a Cu-Al-Ni single crystal under compression, with critical super-nuclei size L2c around 500 nm. When the sample size D decreases below L2c, the superelasticity behavior changes from a flat stress plateau to a continuously rising stress-strain curve. Such size dependence definitely would impact the application of shape memory alloys in miniaturized MEMS/NEMS devices. PMID:24384687

Liu, Lifeng; Ding, Xiangdong; Li, Ju; Lookman, Turab; Sun, Jun

2014-02-21

231

Direct Observation of Fatigue Cracking in the Fuel Plate Using the Scanning Electron Microscope  

NASA Astrophysics Data System (ADS)

Safety and environmental considerations play the important role in selecting and processing fusion materials. Fatigue impairs the reliability of the components utilized in the fusion reactor. In this paper, we described the fatigue cracking mechanism of the sandwich structure of dispersion U3Si2-Al fuel plates using the in situ scanning electron microscope. Direct observations indicated that the failure originates in the vicinal clad-meat interface under tensile-tensile cyclic and three points bending loading. The fatigue crack occurs in two typical fracture modes — Mode-I and the mixed-mode of I and II. The effect of the process of U3Si2-Al fuel meat on the fatigue behaviors of the sandwich structure is obvious.

Wang, Xi-Shu; Xu, Yong; Xu, Xian-Qi

2004-05-01

232

Direct observation of the nuclear motion during ultrafast intramolecular proton transfer  

NASA Astrophysics Data System (ADS)

The skeletal motions contributing to the reaction path of the ultrafast excited state intramolecular proton transfer (ESIPT) are determined directly from time resolved measurements. We investigate the ESIPT in the compounds 2-(2'-hydroxyphenyl)benzothiazole, 2-(2'-hydroxyphenyl)benzoxazole and ortho-hydroxybenzaldehyde by UV-visible pump-probe spectroscopy with 30 fs resolution. The proton transfer is observed in real time and a characteristic 'ringing' of the molecule in a small number of vibrational modes is found after the reaction. The results show that a bending motion of the molecular skeleton reduces the proton donor-acceptor distance and an electronic configuration change occurs at a sufficient contraction leading to the bonds of the product conformer. The process evolves as a ballistic wavepacket propagation on an adiabatic potential energy surface. The proton is shifted by the skeletal motions from the donor to the acceptor site and tunneling has not to be considered.

Lochbrunner, S.; Stock, K.; Riedle, E.

2004-08-01

233

Direct observation of the hyperfine transition of ground-state positronium.  

PubMed

We report the first direct measurement of the hyperfine transition of the ground state positronium. The hyperfine structure between ortho-positronium and para-positronium is about 203 GHz. We develop a new optical system to accumulate about 10 kW power using a gyrotron, a mode converter, and a Fabry-Pérot cavity. The hyperfine transition has been observed with a significance of 5.4 standard deviations. The transition probability is measured to be A = 3.1(-1.2)(+1.6) × 10(-8) s(-1) for the first time, which is in good agreement with the theoretical value of 3.37 × 10(-8) s(-1). PMID:23004598

Yamazaki, T; Miyazaki, A; Suehara, T; Namba, T; Asai, S; Kobayashi, T; Saito, H; Ogawa, I; Idehara, T; Sabchevski, S

2012-06-22

234

The directivity of high-energy emission from solar flares - Solar Maximum Mission observations  

NASA Technical Reports Server (NTRS)

The data base consisting of flares detected by the gamma-ray spectrometer (GRS) on board the Solar Maximum Mission (SMM) satellite is used to study the directivity of high-energy radiation. A number of observations are presented that, strongly indicate that the high-energy emission from flares is anisotropic. They are the following: (1) the fraction of events detected at energies above 300 keV near the limb is higher than is expected for isotropically emitting flares; (2) there is a statistically significant center-to-limb variation in the 300 keV to 1 MeV spectra of flares detected by the SMM GRS; (3) the 25-200 keV hard X-ray spectra measured during the impulsive phase by the SMM GRS show a center-to-limb variation; and (4) nearly all of the events detected at above 10 MeV are located near the limb.

Vestrand, W. Thomas; Forrest, D. J.; Chupp, E. L.; Rieger, E.; Share, G. H.

1987-01-01

235

Direct Observation of Morphological Tranformation from Twisted Ribbons into Helical Ribbons  

SciTech Connect

We report on the direct observation of a nanostructural transformation from a twisted ribbon to a helical ribbon in supramolecular assemblies of peptide amphiphiles. Using cryogenic electron microscopy, a peptide amphiphile molecule containing aromatic residues was found to first assemble into short twisted ribbons in the time range of seconds, which then elongate in the time scale of minutes, and finally transform into helical ribbons over the course of weeks. By synthesizing an analogous molecule without the aromatic side groups, it was found that a cylindrical nanostructure is formed that does not undergo any transitions during the same time period. The study of metastable states in peptide aggregation can contribute to our understanding of amyloid-related diseases, such as Alzheimer's disease.

Pashuck, E.Thomas; Stupp, Samuel I. (NWU)

2010-07-01

236

Build a Better Mouse: Directly-Observed Issues in Computer Use for Adults with SMI  

PubMed Central

Integrating information technology into healthcare has the potential to bring treatment to hard-to-reach people. Individuals with serious mental illness (SMI), however, may derive limited benefit from these advances in care because of lack of computer ownership and experience. To date, conclusions about the computer skills and attitudes of adults with SMI have been based primarily on self-report. In the current study, 28 psychiatric outpatients with co-occurring cocaine use were interviewed about their computer use and opinions, and 25 were then directly observed using task analysis and think aloud methods as they navigated a multi-component health informational website. Participants reported low rates of computer ownership and use, and negative attitudes towards computers. Self-reported computer skills were higher than demonstrated in the task analysis. However, some participants spontaneously expressed more positive attitudes and greater computer self-efficacy after navigating the website. Implications for increasing access to computer-based health information are discussed.

Black, Anne C.; Serowik, Kristin L.; Schensul, Jean J.; Bowen, Anne M.; Rosen, Marc I.

2014-01-01

237

Patient satisfaction with care at directly observed therapy programs for tuberculosis in New York City.  

PubMed Central

OBJECTIVES: This study examined patients' satisfaction with New York State's tuberculosis (TB) directly observed therapy (DOT) programs in New York City. METHODS: A survey was conducted of 435 patients at 19 public, private, and community-based TB DOT clinics about their satisfaction with various aspects of the programs. RESULTS: Patients identified the opportunity to receive good medical care as the most important aspect of TB DOT. Also significant was the supportiveness of DOT staff. Receiving incentives to encourage participation was statistically less important. Half of the patients reported being better off with DOT than with self-supervised care. CONCLUSIONS: This study confirms the value of patient-focused care among inner-city TB patients.

Davidson, H; Smirnoff, M; Klein, S J; Burdick, E

1999-01-01

238

A novel approach to directly observed therapy for tuberculosis in an HIV-endemic area.  

PubMed Central

OBJECTIVES: This study evaluated a novel approach to the delivery of directly observed therapy (DOT) for tuberculosis in Haiti. METHODS: A total of 194 patients (152 HIV seropositive, 42 HIV seronegative) received daily unsupervised triple-drug therapy for 4 to 8 weeks, followed by twice-weekly 2-drug therapy for the remainder of the 6-month period. DOT was deferred until initiation of the twice-weekly phase. RESULTS: A total of 169 of 194 patients (87.1%) completed the 6-month course. The program of deferred DOT had an effectiveness of 85%. Overall cost was reduced by approximately 40%. CONCLUSIONS: Flexible approaches to DOT, integrating behavioral knowledge, cost considerations, and practicality may improve completion rates and program effectiveness.

Desvarieux, M; Hyppolite, P R; Johnson, W D; Pape, J W

2001-01-01

239

Direct observation of Kramers-Kronig self-phasing in coherently combined fiber lasers.  

PubMed

A highly stable coherent beam-combining system has been designed to measure self-phasing in fiber lasers due to nonlinear effects. Whereas self-phasing in previous coherent combination experiments has been principally attributed to wavelength shifting, these wavelength effects have been efficiently suppressed in our experiment by using a dual-core fiber with closely balanced optical path lengths. The self-phasing from nonlinear effects could then be measured independently and directly by common-path interferometry with a probe laser. The Kramers-Kronig effect in the fiber gain media was observed to induce a phase shift that effectively canceled the applied path length errors, resulting in efficient lasing under all phase conditions. This process was demonstrated to result in robust lasing over a large range of pump conditions. PMID:24321934

Chiang, Hung-Sheng; Leger, James R; Nilsson, Johan; Sahu, Jayanta

2013-10-15

240

Direct observation of the double Auger decay of a {ital K} hole  

SciTech Connect

The double Auger (DA) decay of a {ital K} hole has been observed directly by detecting the two emitted electrons in coincidence. The hole was created in {sup 37}Cl following the electron-capture decay of {sup 37}Ar. The probability of DA decay, per Auger decay, with the two electrons both having an energy greater than 250 eV was found to be 3.7{plus_minus}0.2{percent}. The DA probability was found to decrease exponentially as the energy partitioning between the two electrons changed from the asymmetric case ({ital E}{sub 1}{gt}{ital E}{sub 2}) to the symmetric case ({ital E}{sub 1}{approx_equal}{ital E}{sub 2}). The DA probability accounts for the bulk of the intensity of high charge states previously measured in {sup 37}Cl. {copyright} {ital 1996 The American Physical Society.}

Hindi, M.M.; Zhu, L.; Avci, R.; Miocinovic, P.M.; Kozub, R.L.; Lapeyre, G.J. [Department of Physics, Tennessee Technological University, Cookeville, Tennessee 38505 (United States)] [Department of Physics, Tennessee Technological University, Cookeville, Tennessee 38505 (United States); [Department of Physics, Montana State University, Bozeman, Montana 59717 (United States)

1996-06-01

241

Assessing age-related morphology of the pubic symphysis from digital images versus direct observation.  

PubMed

The increasingly global role of a forensic anthropologist necessitates a proper means for archiving evidence for re-examination. Large quantities of evidence can be stored and be made readily accessible through digital imaging. This study focuses on age assessment from digital photographs for personal identity reconstructions. A comparison of 52 Suchey-Brooks scores assigned to digital images and actual bone revealed that age assessment from digital images can be completed with accuracy. Coefficients of concordance imply that there significant agreement between osteological assessment of aging criteria from digital images and direct observation-greater than random change alone (p < 0.05). However, assessments from images should be approached with caution since there are inherent limitations of the naked eye in identifying morphological changes in certain skeletal features, especially where older adults are concerned. Although there is no replacement for a hands-on physical assessment, a digital archive may facilitate the global needs of the forensic anthropologist. PMID:16078479

Sitchon, Myra L; Hoppa, Robert D

2005-07-01

242

Direct observation of half-metallicity in the Heusler compound Co2MnSi.  

PubMed

Ferromagnetic thin films of Heusler compounds are highly relevant for spintronic applications owing to their predicted half-metallicity, that is, 100% spin polarization at the Fermi energy. However, experimental evidence for this property is scarce. Here we investigate epitaxial thin films of the compound Co2MnSi in situ by ultraviolet-photoemission spectroscopy, taking advantage of a novel multi-channel spin filter. By this surface sensitive method, an exceptionally large spin polarization of () % at room temperature is observed directly. As a more bulk sensitive method, additional ex situ spin-integrated high energy X-ray photoemission spectroscopy experiments are performed. All experimental results are compared with advanced band structure and photoemission calculations which include surface effects. Excellent agreement is obtained with calculations, which show a highly spin polarized bulk-like surface resonance ingrained in a half metallic bulk band structure. PMID:24875774

Jourdan, M; Minár, J; Braun, J; Kronenberg, A; Chadov, S; Balke, B; Gloskovskii, A; Kolbe, M; Elmers, H J; Schönhense, G; Ebert, H; Felser, C; Kläui, M

2014-01-01

243

Direct observation of Young's double-slit interferences in vibrationally resolved photoionization of diatomic molecules  

PubMed Central

Vibrationally resolved valence-shell photoionization spectra of H2, N2 and CO have been measured in the photon energy range 20–300 eV using third-generation synchrotron radiation. Young’s double-slit interferences lead to oscillations in the corresponding vibrational ratios, showing that the molecules behave as two-center electron-wave emitters and that the associated interferences leave their trace in the angle-integrated photoionization cross section. In contrast to previous work, the oscillations are directly observable in the experiment, thereby removing any possible ambiguity related to the introduction of external parameters or fitting functions. A straightforward extension of an original idea proposed by Cohen and Fano [Cohen HD, Fano U (1966) Phys Rev 150:30] confirms this interpretation and shows that it is also valid for diatomic heteronuclear molecules. Results of accurate theoretical calculations are in excellent agreement with the experimental findings.

Canton, Sophie E.; Plesiat, Etienne; Bozek, John D.; Rude, Bruce S.; Decleva, Piero; Martin, Fernando

2011-01-01

244

Direct observations of gas-hydrate formation in natural porous media on the micro-scale  

NASA Astrophysics Data System (ADS)

Gas hydrates (GH) are crystalline, inclusion compounds consisting of hydrogen-bonded water network encaging small gas molecules such as methane, ethane, CO2, etc (Sloan and Koh 2008). Natural gas hydrates are found worldwide in marine sediments and permafrost regions as a result of a reaction of biogenic or thermogenic gas with water under elevated pressure. Although a large amount of research on GH has been carried out over the years, the micro-structural aspects of GH growth, and in particular the contacts with the sedimentary matrix as well as the details of the distribution remain largely speculative. The present study was undertaken to shed light onto the well-established but not fully understood seismic anomalies, in particular the unusual attenuation of seismic waves in GH-bearing sediments, which may well be linked to micro-structural features. Observations of in-situ GH growth have been performed in a custom-build pressure cell (operating pressures up to several bar) mounted at the TOMCAT beam line of SLS/ PSI. In order to provide sufficient absorption contrast between phases and reduce pressure requirements for the cell we have used Xe instead of CH4. To the best of our knowledge this represents the first direct observation of GH growth in natural porous media with sub-micron spatial resolution and gives insight into the nucleation location and growth process of GH. The progress of the formation of sI Xe-hydrate in natural quartz sand was observed with a time-resolution of several minutes; the runs were conducted with an excess of a free-gas phase and show that the nucleation starts at the gas-water interface. Initially, a GH film is formed at this interface with a typical thickness of several ?m; this film may well be permeable to gas as suggested in the past - which would explain the rapid transport of gas molecules for further conversion of water to hydrate, completed in less than 20 min. Clearly, initially the growth is directed mainly into the liquid (and not into the gas phase as sometimes suggested). The observations of the 2D slices after full transformation show for all systems studied that hydrates tend to concentrate in the center of pore spaces and do not adhere in a systematic manner to quartz grains. Whether or not a thin film of water remained at the quartz-GH interface after completion of the reaction is presently under investigation. Sloan, E.D., Koh, C.A., (2008) Clathrate hydrates of natural gases. CRC Press, Boca Raton, FL.

Chaouachi, M.; Sell, K.; Falenty, A.; Enzmann, F.; Kersten, M.; Pinzer, B.; Saenger, E. H.; Kuhs, W. F.

2013-12-01

245

Ultrasound Open Channel Flow-Speed Measurement Based on the Lateral Directional Echo Observations  

NASA Astrophysics Data System (ADS)

Conventional ultrasonic flowmeters have a problem in measuring the small open channel fluid flow. To solve this problem, a lateral observation technique using a single transmitter/receiver transducer attached at the bottom of the pipe was proposed. Pulse echo signals scattered from the particles in the medium were repetitively recorded with a constant time interval. From the slope of the correlation peak amplitude with the variation in pulse echo excitation time, the flow speed of the medium was estimated. The method has an advantage in that the variation in flow speed in the vertical depth direction is directly measured with a minimum measurement space. Moreover, the fluctuations caused by the turbulent water can be avoided compared with the case of a conventional method based on the time estimation method. Bubbles were generated by an aspirator and flour powder was mixed with water as scatterers in the imitated drainage water. The flow speed of water was measured with respect to the inflowing fluid volume. Moreover, vertical flow speed profiles were measured and compared with fluid flow simulation results. The results showed that the precision of the measured flow speed was satisfactory and tolerant against the turbulence of the water flow medium.

Nishimura, Ichiro; Ishigamori, Mitsuhide; Yamada, Akira

2012-07-01

246

Directionality and variability of energetic neutral hydrogen fluxes observed by Mars Express  

NASA Astrophysics Data System (ADS)

Using data collected by the neutral particle detector of the analyzer of space plasmas and energetic atoms on board Mars Express, we establish the global morphology of hydrogen energetic neutral atom (ENA) fluxes. The observations were conducted in March-July 2004 and reveal that low flux ENAs (<5×105cm-2s-1sr-1) are emitted roughly isotropically from the dayside of the planet. These ENA emissions originate from the backscattering of the hydrogen ENAs produced by the charge exchange of the upstream solar wind in the extended Martian exosphere. ENAs of higher fluxes are emitted preferentially in the directions perpendicular to the undisturbed solar wind velocity. This population is due to the charge exchange of the magnetosheath plasma. At a great distance, these ENA emissions resemble a thick layer or a wall. The emissions are enhanced in the direction opposite to the convective electric field (Ec). This enhancement reflects the asymmetric shape of the induced magnetic boundary that is close to the planet hemisphere where the Ec points toward the Sun-Mars line (-Ec hemisphere). The ENA flux shows a positive correlation with the solar wind dynamic pressure. The asymmetry in the ENA emissions is modest during quiet solar wind conditions but becomes more pronounced when the solar wind dynamic pressure increases.

Wang, X.-D.; Barabash, S.; Futaana, Y.; Grigoriev, A.; Wurz, P.

2013-12-01

247

Direct Observations of the Mechanical Behaviors of the Cytoskeleton in Living Fibroblasts  

PubMed Central

Cytoskeletal proteins tagged with green fluorescent protein were used to directly visualize the mechanical role of the cytoskeleton in determining cell shape. Rat embryo (REF 52) fibroblasts were deformed using glass needles either uncoated for purely physical manipulations, or coated with laminin to induce attachment to the cell surface. Cells responded to uncoated probes in accordance with a three-layer model in which a highly elastic nucleus is surrounded by cytoplasmic microtubules that behave as a jelly-like viscoelastic fluid. The third, outermost cortical layer is an elastic shell under sustained tension. Adhesive, laminin-coated needles caused focal recruitment of actin filaments to the contacted surface region and increased the cortical layer stiffness. This direct visualization of actin recruitment confirms a widely postulated model for mechanical connections between extracellular matrix proteins and the actin cytoskeleton. Cells tethered to laminin-treated needles strongly resisted elongation by actively contracting. Whether using uncoated probes to apply simple deformations or laminin-coated probes to induce surface-to-cytoskeleton interaction we observed that experimentally applied forces produced exclusively local responses by both the actin and microtubule cytoskeleton. This local accomodation and dissipation of force is inconsistent with the proposal that cellular tensegrity determines cell shape.

Heidemann, Steven R.; Kaech, Stefanie; Buxbaum, Robert E.; Matus, Andrew

1999-01-01

248

Direct Determination of Auroral Kilomeric Radiation Burst Locations Using Cluster VLBI Delay Observations  

NASA Astrophysics Data System (ADS)

We have used the Wideband Data (WBD) instrument on Cluster to determine source locations of auroral kilometric radiation (AKR) bursts using multiple spacecraft in a very long baseline interferometry (VLBI) mode. The technique involves measuring the delays of AKR impulsive bursts on each of several independent baselines between pairs of spacecraft with sub-millisecond accuracy. The delays are combined to solve for source location by triangulation. The accuracy of the technique depends on the Cluster orientation and distance from Earth, but typical uncertainties are 200-1000 km in a plane perpendicular to the source-Cluster line of sight, and somewhat larger along this direction. We have analyzed AKR burst locations for more than 30 events, and have compared the derived positions with contemporaneous images of auroral taken by imagers on the POLAR and Image spacecraft. We find that the AKR locations are consistent with emission occurring at or near the local gyrofrequency, and the bursts tend to occur along magnetic field lines located above regions of bright regions in the auroral oval. These observations are the first direct 3-dimensional measurement of AKR source location. >http://denali.physics.uiowa.edu/rlm/research/vlbi-akr

Mutel, R. L.; Gurnett, D. A.; Christopher, I.

2001-12-01

249

Microscopic Observations on the Origin of Defects During Machining of Direct Aged (DA) Inconel 718 Superalloy  

NASA Astrophysics Data System (ADS)

Surface quality of advanced superalloys after machining is one of the major issues in the aerospace industry because it directly affects service characteristics of the machined part. Tool life of cemented carbide inserts with the TiAlN coating during machining of direct aged DA 718 alloys under roughing and finishing conditions has been under study. The defect origin on the surface of the machined part was investigated. Metallographic observations of the DA 718 were made using optical metallography and SEM/EDS. To find out the origins of surface defect formation, the morphology of machined parts and cross sections of the machined surfaces have been investigated. Two major categories of defects were detected on the surface of the machined part: cracks and tears. The origin of the cracks on the machined surface is related to shearing of the primary complex TiC/NbC carbide revealed in a structure of DA 718 alloy. At the same time, Nb-rich regions of the primary complex carbide interact with the environment (oxygen from air) during machining with further formation of low strength oxide layer on the surface, forming tears.

Dosbaeva, G. K.; Veldhuis, S. C.; Elfizy, A.; Fox-Rabinovich, G.; Wagg, T.

2010-11-01

250

Ultrafast electron diffraction and direct observation of transient structures in a chemical reaction.  

PubMed

Ultrafast electron diffraction is a unique method for the studies of structural changes of complex molecular systems. In this contribution, we report direct ultrafast electron diffraction study of the evolution of short-lived intermediates in the course of a chemical change. Specifically, we observe the transient intermediate in the elimination reaction of 1,2-diiodotetrafluoroethane (C2F4I2) to produce the corresponding ethylene derivative by the breakage of two carbon-iodine, C---I, bonds. The evolution of the ground-state intermediate (C2F4I radical) is directly revealed in the population change of a single chemical bond, namely the second C---I bond. The elimination of two iodine atoms was shown to be nonconcerted, with reaction time of the second C---I bond breakage being 17 +/- 2 ps. The structure of the short-lived C2F4I radical is more favorable to the classical radical structure than to the bridged radical structure. This leap in our ability to record structural changes on the ps and shorter time scales bodes well for many future applications in complex molecular systems. PMID:9892634

Cao, J; Ihee, H; Zewail, A H

1999-01-19

251

Direct observation of hierarchical nucleation of martensite and size-dependent superelasticity in shape memory alloys  

NASA Astrophysics Data System (ADS)

Martensitic transformation usually creates hierarchical internal structures beyond mere change of the atomic crystal structure. Multi-stage nucleation is thus required, where nucleation (level-1) of the underlying atomic crystal lattice does not have to be immediately followed by the nucleation of higher-order superstructures (level-2 and above), such as polysynthetic laths. Using in situ transmission electron microscopy (TEM), we directly observe the nucleation of the level-2 superstructure in a Cu-Al-Ni single crystal under compression, with critical super-nuclei size L2c around 500 nm. When the sample size D decreases below L2c, the superelasticity behavior changes from a flat stress plateau to a continuously rising stress-strain curve. Such size dependence definitely would impact the application of shape memory alloys in miniaturized MEMS/NEMS devices.Martensitic transformation usually creates hierarchical internal structures beyond mere change of the atomic crystal structure. Multi-stage nucleation is thus required, where nucleation (level-1) of the underlying atomic crystal lattice does not have to be immediately followed by the nucleation of higher-order superstructures (level-2 and above), such as polysynthetic laths. Using in situ transmission electron microscopy (TEM), we directly observe the nucleation of the level-2 superstructure in a Cu-Al-Ni single crystal under compression, with critical super-nuclei size L2c around 500 nm. When the sample size D decreases below L2c, the superelasticity behavior changes from a flat stress plateau to a continuously rising stress-strain curve. Such size dependence definitely would impact the application of shape memory alloys in miniaturized MEMS/NEMS devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr05258c

Liu, Lifeng; Ding, Xiangdong; Li, Ju; Lookman, Turab; Sun, Jun

2014-01-01

252

Direct observation of macrostructure formation of hierarchically structured meso-macroporous aluminosilicates with 3D interconnectivity by optical microscope.  

PubMed

Hierarchically structured spongy meso-macroporous aluminosilicates with high tetrahedral aluminum content were synthesized from a mixture of single molecular alkoxide precursor, (sec-BuO)2-Al-O-Si(OEt)3, already containing Si-O-Al bonds, and a silica coreactant, tetramethoxysilane (TMOS). The spontaneous byproduct templated macroporous structure formation has been directly visualized using in situ high-resolution optical microscopy (OM), allowing the crucial observation of a microbubble dispersion which is directly correlated to the macrostructure observed by electronic microscopies (SEM and TEM). This discovery leads to a comparative study with meso-macroporous pure metal oxide and to a proposal of the formation mechanism of meso-macroporous aluminosilicates with 3D interconnectivity. The aluminosilicate phase/microbubbles emulsion is produced by a phase separation process occurring between the aluminosilicate nanoparticles and the liquid hydrolysis-condensation reaction byproducts (water, methanol, ethanol, and butanol). The use of alkoxysilane improves the heterocondensation rates between the highly reactive aluminum alkoxide part of the single precursor and added silica species but, above all, leads to the spontaneous generation of an unusual meso-macroporosity in alkaline media. The particles obtained at pH = 13.0 featured regular micrometer-sized macrospheres separated by very thin mesoporous walls and connected by submicrometric openings, providing a 3D interconnectivity. The slight increase in pH value to 13.5 induced significant modifications in morphology and textural properties due to the slower gelification process of the aluminosilicate phase, resulting in the formation of an aluminosilicate material constituted of 1-2 µm large independent hollow mesoporous spheres. PMID:21275420

Lemaire, Arnaud; Rooke, Joanna Claire; Chen, Li-Hua; Su, Bao-Lian

2011-03-15

253

Direct observation and control of supported lipid bilayer formation with interferometric scattering microscopy.  

PubMed

Supported lipid bilayers (SLB) are frequently used to study processes associated with or mediated by lipid membranes. The mechanism by which SLBs form is a matter of debate, largely due to the experimental difficulty associated with observing the adsorption and rupture of individual vesicles. Here, we used interferometric scattering microscopy (iSCAT) to directly visualize membrane formation from nanoscopic vesicles in real time. We observed a number of previously proposed phenomena such as vesicle adsorption, rupture, movement, and a wave-like bilayer spreading. By varying the vesicle size and the lipid-surface interaction strength, we rationalized and tuned the relative contributions of these phenomena to bilayer formation. Our results support a model where the interplay between bilayer edge tension and the overall interaction energy with the surface determine the mechanism of SLB formation. The unique combination of sensitivity, speed, and label-free imaging capability of iSCAT provides exciting prospects not only for investigations of SLB formation, but also for studies of assembly and disassembly processes on the nanoscale with previously unattainable accuracy and sensitivity. PMID:24251388

Andrecka, Joanna; Spillane, Katelyn M; Ortega-Arroyo, Jaime; Kukura, Philipp

2013-12-23

254

Direct observation of the capillary mechanisms of liquid-liquid entrapment and mobilization  

NASA Astrophysics Data System (ADS)

The dissertation develops further insight into the behavior of liquid-liquid flow in porous media. This topic is of great importance with applications in chemical reaction engineering, enhanced oil recovery, and environmental remediation. This work focuses on the experimental observation of invading immiscible drops, the long term behavior of their interface, and their entrapment via capillary pressure and mobilization through vibratory stimulation. Using a simplified capillary physics mechanism several specific predictions can be made. So far these theories have generally agreed with CFD simulations, however a direct comparison to physical experiments is needed. Experiments were conducted using single pore glass capillaries. Straight capillaries were used to study the film thickness left by an invading drop, which is critical for determining realistic initial conditions for the interface theory. A range of constricted capillaries were used in verifying the ``breakup criterion'' was influenced only by the geometric parameters of the capillary and not flow regimes. Additionally, the experiments and theory demonstrates qualitative agreement with respect to the evolution of the liquid-liquid interface. Finally, the theory of vibratory mobilization was verified by trapping single drops with a pressure below their mobilization threshold and observing the drop's mobilization over several oscillations. The level of agreement between experiment, theory and CFD demonstrates the utility of the capillary physics mechanism in terms of reducing computational costs. The next goal is extending the theory to networks of pores so we can further our understanding of the oil mobilization and related processes, leading to useful technical applications.

Gaul, William Gerard

255

Experimental technique for direct observation of onset of reaction in shocked powder mixtures  

NASA Astrophysics Data System (ADS)

A new experimental technique was developed to directly observe the onset of shock initiation in powder mixtures contained in recovery capsules over time scales ranging from hundreds of nanoseconds to at least hundreds of milliseconds. Simultaneously with a thermocouple embedded in the test mixture to monitor bulk temperature changes, a photomultiplier tube detected light emissions produced by the reacting sample. A window/optic fiber system was developed that remained intact and did not move during the experiment. A polycarbonate window was placed into a steel recovery capsule, which was held solidly in place in a steel anvil designed to protect the fiber optic and to prevent motion of the window. Samples of as-blended 5Ti+3Si powders and ball-milled mixtures 5Ti+3Si were tested in this setup. In all experiments, a weak light emission peak was observed upon shock passage followed by much more intense light beginning a few milliseconds to a few hundreds of milliseconds later. The intense light emissions occurred at approximately the same time as a bulk temperature increase measured with the thermocouple. These results suggest that only a very small fraction of the sample was initiated by the shock.

Jetté, Francois-Xavier; Goroshin, Sam; Higgins, Andrew; Frost, David; Lee, Julian

2012-03-01

256

Experimental Technique for Direct Observation of Onset of Reaction in Shocked Powder Mixtures  

NASA Astrophysics Data System (ADS)

A new experimental technique was developed to directly observe the onset of shock initiation in powder mixtures contained in recovery capsules over time scales ranging from hundreds of nanoseconds to at least hundreds of milliseconds. Simultaneously with a thermocouple embedded in the test mixture to monitor bulk temperature changes, a photomultiplier tube detected light emissions produced by the reacting sample. A particular window/optic fiber system was developed that remained intact and did not move during the experiment. A T-shaped polycarbonate window was placed into a steel recovery capsule, which was held solidly in place in a heavy steel anvil designed to protect the fiber optic and to prevent motion of the polycarbonate window. Samples of as-blended 5Ti+3Si powders and ball-milled mixtures 5Ti+3Si were tested in this setup. In all experiments, a weak light emission peak was observed upon shock passage followed by much more intense light emissions beginning a few milliseconds to a few hundreds of milliseconds later. The intense light emissions occurred at approximately the same time as a bulk temperature increase measured with the thermocouple. These results suggest that only a very small fraction of the sample was initiated by the shock. This setup shows promise for further studies of shock initiation in reactive powders.

Jetté, François-Xavier; Goroshin, Sam; Higgins, Andrew; Frost, David; Lee, Julian

2011-06-01

257

Direct observation of polarons in electron populated quantum dots by resonant Raman scattering.  

PubMed

The general problem of the pairing of strongly interacting elementary excitations producing new quasiparticles such as polarons arises in many areas of solid state physics. Recent interest in polaron formation in semiconductor quantum dots has been motivated by the need to understand the physical nature of the carrier relaxation processes and their role in quantum-dot based devices. We report on the direct observation of polarons in InAs/GaAs self-assembled quantum dots populated by few electrons where the polarons are strongly coupled modes of quantum dot phonons and electron intersublevel transitions. The degree of coupling is varied in a systematic way in a set of samples having electron intersublevel spacing changing from larger to smaller than the longitudinal optical phonon energy. The signature of polarons is evidenced clearly by the observation of a large (12-20 meV) anticrossing for both InAs and GaAs-like quantum dot phonons using resonant Raman spectroscopy. PMID:18464407

Aslan, B; Liu, H C; Korkusinski, M; Hawrylak, P; Lockwood, D J

2008-02-01

258

Direct observation of small cluster mobility and ripening. [during annealing of metal films on amorphous substrates  

NASA Technical Reports Server (NTRS)

Direct evidence is reported for the simultaneous occurrence of Ostwald ripening and short-distance cluster mobility during annealing of discontinuous metal films on clean amorphous substrates. The annealing characteristics of very thin particulate deposits of silver on amorphized clean surfaces of single crystalline thin graphite substrates were studied by in-situ transmission electron microscopy (TEM) under controlled environmental conditions (residual gas pressure of 10 to the minus 9th power torr) in the temperature range from 25 to 450 C. Sputter cleaning of the substrate surface, metal deposition, and annealing were monitored by TEM observation. Pseudostereographic presentation of micrographs in different annealing stages, the observation of the annealing behavior at cast shadow edges, and measurements with an electronic image analyzing system were employed to aid the visual perception and the analysis of changes in deposit structure recorded during annealing. Slow Ostwald ripening was found to occur in the entire temperature range, but the overriding surface transport mechanism was short-distance cluster mobility.

Heinemann, K.; Poppa, H.

1975-01-01

259

Direct observations of basin-wide acidification of the North Pacific Ocean  

NASA Astrophysics Data System (ADS)

Global ocean acidification is a prominent, inexorable change associated with rising levels of atmospheric CO2. Here we present the first basin-wide direct observations of recently declining pH, along with estimates of anthropogenic and non-anthropogenic contributions to that signal. Along 152°W in the North Pacific Ocean (22-56°N), pH changes between 1991 and 2006 were essentially zero below about 800 m depth. However, in the upper 500 m, significant pH changes, as large as -0.06, were observed. Anthropogenic and non-anthropogenic contributions over the upper 800 m are estimated to be of similar magnitude. In the surface mixed layer (depths to ˜100 m), the extent of pH change is consistent with that expected under conditions of seawater/atmosphere equilibration, with an average rate of change of -0.0017/yr. Future mixed layer changes can be expected to closely mirror changes in atmospheric CO2, with surface seawater pH continuing to fall as atmospheric CO2 rises.

Byrne, Robert H.; Mecking, Sabine; Feely, Richard A.; Liu, Xuewu

2010-01-01

260

Direct Observation of Controlled Melting and Resolidification of Succinonitrile Mixtures in a Microgravity Environment  

NASA Technical Reports Server (NTRS)

In support of the Pore Formation and Mobility Investigation (PFMI) direct observation of experiments on the controlled melting and subsequent resolidification of succinonitrile were conducted in the glovebox facility (GBX) of the International Space Station (ISS). Samples were prepared on ground by filling glass tubes, 1 cm ID and approximately 30 cm in length, with pure succinonitrile (SCN) and SCN-Water mixtures under 450 millibar of nitrogen. Experimental processing parameters of temperature gradient and translation speed, as well as camera settings, were remotely monitored and manipulated from the ground Telescience Center (TSC) at the Marshall Space Flight Center. Sample temperatures are monitored by six in situ thermocouples. Real time visualization during melt back revealed bubbles of different sizes initiating at the solid/liquid interface, their release, interactions, and movement into the temperature field ahead of them. Subsequent re-solidification examined planar interface breakdown and the transition to steady-state dendritic growth. A preliminary analysis of the observed phenomena and its implication to future microgravity experiments is presented and discussed.

Grugel, R. N.; Anilkumar, A. V.; Lee, C. P.

2004-01-01

261

Observing and Improving Hand Hygiene Compliance: Implementation and Refinement of an Electronic-Assisted Direct-Observer Hand Hygiene Audit Program  

PubMed Central

We implemented a direct-observer hand hygiene audit program that used trained observers, wireless data entry devices, and an intranet portal. We improved the reliability and utility of the data by standardizing audit processes, regularly retraining auditors, developing an audit guidance tool, and reporting weighted composite hand hygiene compliance scores.

Chen, Luke F.; Carriker, Charlene; Staheli, Russell; Isaacs, Pamela; Elliott, Brandon; Miller, Becky A.; Anderson, Deverick J.; Moehring, Rebekah W.; Vereen, Sheila; Bringhurst, Judie; Rhodes, Lisa; Strittholt, Nancy; Sexton, Daniel J.

2013-01-01

262

An instrument for direct observations of seismic and normal-mode rotational oscillations of the Earth.  

PubMed

The rotations around the vertical axis associated with the normal mode oscillations of the Earth and those induced by the seismic and other disturbances have been very difficult to observe directly. Such observations will provide additional information for 3D modeling of the Earth and for understanding earthquakes and other underground explosions. In this paper, we describe the design of an instrument capable of measuring the rotational motions associated with the seismic oscillations of the Earth, including the lowest frequency normal mode at nu approximately 3.7 x 10(-4) Hz. The instrument consists of a torsion balance with a natural frequency of nu(0) approximately 1.6 x 10(-4) Hz, which is observed by an autocollimating optical lever of high angular resolution and dynamic range. Thermal noise limits the sensitivity of the apparatus to amplitudes of approximately 1.5 x 10(-9) rad at the lowest frequency normal mode and the sensitivity improves as nu(-3/2) with increasing frequency. Further improvements in sensitivity by about two orders of magnitude may be achieved by operating the balance at cryogenic temperatures. Alternatively, the instrument can be made more robust with a reduced sensitivity by increasing nu(0) to approximately 10(-2) Hz. This instrument thus complements the ongoing effort by Igel and others to study rotational motions using ring laser gyroscopes and constitutes a positive response to the clarion call for developments in rotation seismology by Igel, Lee, and Todorovska [H. Igel, W.H.K. Lee and M.I. Todorovska, AGU Fall Meeting 2006, Rotational Seismology Sessions: S22A,S23B, Inauguration of the International Working Group on Rotational Seismology (IWGoRS)]. PMID:17438268

Cowsik, R

2007-04-24

263

An instrument for direct observations of seismic and normal-mode rotational oscillations of the Earth  

PubMed Central

The rotations around the vertical axis associated with the normal mode oscillations of the Earth and those induced by the seismic and other disturbances have been very difficult to observe directly. Such observations will provide additional information for 3D modeling of the Earth and for understanding earthquakes and other underground explosions. In this paper, we describe the design of an instrument capable of measuring the rotational motions associated with the seismic oscillations of the Earth, including the lowest frequency normal mode at ? ? 3.7 × 10?4 Hz. The instrument consists of a torsion balance with a natural frequency of ?0 ? 1.6 × 10?4 Hz, which is observed by an autocollimating optical lever of high angular resolution and dynamic range. Thermal noise limits the sensitivity of the apparatus to amplitudes of ? 1.5 × 10?9 rad at the lowest frequency normal mode and the sensitivity improves as ??3/2 with increasing frequency. Further improvements in sensitivity by about two orders of magnitude may be achieved by operating the balance at cryogenic temperatures. Alternatively, the instrument can be made more robust with a reduced sensitivity by increasing ?0 to ?10?2 Hz. This instrument thus complements the ongoing effort by Igel and others to study rotational motions using ring laser gyroscopes and constitutes a positive response to the clarion call for developments in rotation seismology by Igel, Lee, and Todorovska [H. Igel, W.H.K. Lee and M.I. Todorovska, AGU Fall Meeting 2006, Rotational Seismology Sessions: S22A,S23B, Inauguration of the International Working Group on Rotational Seismology (IWGoRS)].

Cowsik, R.

2007-01-01

264

Direct time-resolved observation of molecular dynamics induced by extreme- ultraviolet photoionization  

NASA Astrophysics Data System (ADS)

Laser-generated high-order harmonics provide a source of extreme-ultraviolet radiation with unique capabilities for probing atomic and molecular dynamics. Here we present the first such studies by employing high harmonics in conjunction with coincident electron-ion 3D momentum imaging (COLTRIMS) technique. We generate femtosecond EUV pulses at ˜ 42 eV photon energy by upconverting intense (> 10^14 Wcm-2) 25 fs laser pulses in an argon filled waveguide. Using this ultrashort EUV pulse as a pump, we launch D2, N2 and CO into highly excited states near the molecular double-ionization threshold. The dynamics of these highly excited states unfold along different channels, which are identified by electron-ion correlation. By employing moderate intensity infrared fields, we show that we can influence and probe these dynamics on femtosecond timescales. We observe that the double ionization yield is significantly enhanced by the presence of an IR field in conjunction with the EUV pump. The kinetic energy release evolves as a function of delay time (internuclear distance), allowing us to map excited state dynamics.

Sandhu, Arvinder; Gagnon, Etienne; Paul, Ariel; Murnane, Margaret; Kapteyn, Henry; Ranitovic, Predrag; Cocke, C. Lewis

2007-06-01

265

Direct observation of heat dissipation in individual suspended carbon nanotubes using a two-laser technique  

SciTech Connect

A two-laser technique is used to investigate heat spreading along individual single walled carbon nanotube (SWCNT) bundles in vacuum and air environments. A 532 nm laser focused on the center of a suspended SWCNT bundle is used as a local heat source, and a 633 nm laser is used to measure the spatial temperature profile along the SWCNT bundle by monitoring the G band downshifts in the Raman spectra. A constant temperature gradient is observed when the SWCNT bundle is irradiated in vacuum, giving direct evidence of diffusive transport of the phonons probed by the Raman laser. In air, however, we observe an exponentially decaying temperature profile with a decay length of about 7 {mu}m, due to heat dissipation from the SWCNT bundle to the surrounding gas molecules. The thermal conductivity of the suspended carbon nanotube (CNT) is determined from its electrical heating temperature profile as measured in vacuum and the nanotube bundle diameter measured via transmission electron microscopy. Based on the exponential decay curves measured in three different CNTs in air, the heat transfer coefficient between the SWCNTs and the surrounding air molecules is found to range from 1.5 x 10{sup 3} to 7.9 x 10{sup 4} W/m{sup 2} K, which is smaller than the 1 x 10{sup 5} W/m{sup 2} K thermal boundary conductance value calculated using the kinetic theory of gases. This measurement is insensitive to the thermal contact resistance, as no temperature drops occur at the ends of the nanotube. It is also insensitive to errors in the calibration of the G band temperature coefficient. The optical absorption is also obtained from these results and is on the order of 10{sup -5}.

Hsu, I-Kai; Hung, Wei-Hsuan [Department of Materials Science, University of Southern California, Los Angeles, California 90089 (United States); Pettes, Michael T.; Shi Li [Department of Mechanical Engineering and Center for Nano and Molecular Science and Technology, Texas Materials Institute, University of Texas of Austin, Austin, Texas 78712 (United States); Aykol, Mehmet; Theiss, Jesse; Cronin, Stephen B. [Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089 (United States); Chang, Chia-Chi [Department of Physics, University of Southern California, Los Angeles, California 90089 (United States)

2011-08-15

266

Direct observations of formation and propagation of subpolar eddies into the Subtropical North Atlantic  

NASA Astrophysics Data System (ADS)

Subsurface float and moored observations are presented to show for the first time the formation and propagation of anticyclonic submesoscale coherent vortices that transport relatively cold, fresh subpolar water to the interior subtropical North Atlantic. Acoustically tracked RAFOS floats released in the southward-flowing Western Boundary Current at the exit of the Labrador Sea reveal the formation of three of these eddies at the southern tip of the Grand Banks (42°N, 50°W). Using a recently developed method to detect eddies in float trajectories and estimate their kinematic properties, it was found that the eddies had average rotation periods of 5-7 day at radii of 10-25 km, with mean rotation speeds of up to 0.3 m s-1. One especially long-lived (5.1 months) eddy crossed under the Gulf Stream path and translated southwestward in the subtropical recirculation to at least 35°N, where it hit one of the Corner Rise Seamounts. Velocity, temperature and salinity measurements from a nine-month deployment of two moorings south of the Gulf Stream at 38°N, 50°W reveal the passage of at least two eddies with similar hydrographic and kinematic properties. The core temperature and salinity properties of the eddies imply their formation at intermediate levels of the Labrador Current south of the Tail of the Grand Banks. These observations confirm earlier speculation that eddies form in this region and transport anomalously cold, low-salinity water directly into the subtropical interior. Possible formation mechanisms and potential importance of these eddies to interior ventilation and the equatorward spreading of Labrador Sea Water are discussed.

Bower, Amy S.; Hendry, Ross M.; Amrhein, Daniel E.; Lilly, Jonathan M.

2013-01-01

267

Quantifying aerosol direct effects from broadband irradiance and spectral aerosol optical depth observations  

NASA Astrophysics Data System (ADS)

outline a methodology using broadband and spectral irradiances to quantify aerosol direct effects on the surface diffuse shortwave (SW) irradiance. Best Estimate Flux data span a 13 year timeframe at the Department of Energy Atmospheric Radiation Measurement Program's Southern Great Plains (SGP) site. Screened clear-sky irradiances and aerosol optical depth (AOD), for solar zenith angles ? 65°, are used to estimate clear-sky diffuse irradiances. We validate against detected clear-sky observations from SGP's Basic Radiation System (BRS). BRS diffuse irradiances were in accordance with estimates, producing a root-mean-square error and mean bias errors of 4.0 W/m2 and -1.4 W/m2, respectively. Absolute differences show 99% of estimates within ±10 W/m2 (10%) of the mean BRS observations. Clear-sky diffuse estimates are used to derive quantitative estimates of aerosol radiative effects, represented as the aerosol diffuse irradiance (ADI). ADI is the contribution of diffuse SW to global SW, attributable to scattering of atmospheric transmission by natural plus anthropogenic aerosols. Estimated slope for the ADI as a function of AOD indicates an increase of ~22 W/m2 in diffuse SW for every 0.1 increase in AOD. Such significant increases in the diffuse fraction could possibly increase photosynthesis. Annual mean ADI is 28.2 W/m2, and heavy aerosol loading at SGP provides up to a maximum increase of 120 W/m2 in diffuse SW over background conditions. With regard to seasonal variation, the mean diffuse forcings are 17.2, 33.3, 39.0, and 23.6 W/m2 for winter, spring, summer, and fall, respectively.

Creekmore, Torreon N.; Joseph, Everette; Long, Charles N.; Li, Siwei

2014-05-01

268

Direct Observation of the Myosin Va Recovery Stroke That Contributes to Unidirectional Stepping along Actin  

PubMed Central

Myosins are ATP-driven linear molecular motors that work as cellular force generators, transporters, and force sensors. These functions are driven by large-scale nucleotide-dependent conformational changes, termed “strokes”; the “power stroke” is the force-generating swinging of the myosin light chain–binding “neck” domain relative to the motor domain “head” while bound to actin; the “recovery stroke” is the necessary initial motion that primes, or “cocks,” myosin while detached from actin. Myosin Va is a processive dimer that steps unidirectionally along actin following a “hand over hand” mechanism in which the trailing head detaches and steps forward ?72 nm. Despite large rotational Brownian motion of the detached head about a free joint adjoining the two necks, unidirectional stepping is achieved, in part by the power stroke of the attached head that moves the joint forward. However, the power stroke alone cannot fully account for preferential forward site binding since the orientation and angle stability of the detached head, which is determined by the properties of the recovery stroke, dictate actin binding site accessibility. Here, we directly observe the recovery stroke dynamics and fluctuations of myosin Va using a novel, transient caged ATP-controlling system that maintains constant ATP levels through stepwise UV-pulse sequences of varying intensity. We immobilized the neck of monomeric myosin Va on a surface and observed real time motions of bead(s) attached site-specifically to the head. ATP induces a transient swing of the neck to the post-recovery stroke conformation, where it remains for ?40 s, until ATP hydrolysis products are released. Angle distributions indicate that the post-recovery stroke conformation is stabilized by ?5 kBT of energy. The high kinetic and energetic stability of the post-recovery stroke conformation favors preferential binding of the detached head to a forward site 72 nm away. Thus, the recovery stroke contributes to unidirectional stepping of myosin Va.

Shiroguchi, Katsuyuki; Chin, Harvey F.; Hannemann, Diane E.; Muneyuki, Eiro; De La Cruz, Enrique M.; Kinosita, Kazuhiko

2011-01-01

269

Direct observation of phase transitions: in situ diffraction measurements at the crystal scale  

NASA Astrophysics Data System (ADS)

Phase transitions often display determinate crystallographic orientation relationships between parent and symmetrically degenerate daughter domains. Preferred variant selection and orientation memory under the influence of deviatoric stress are the 'fingerprints' of the transformation mechanism, driving force, and microstructure. For the ?-? transition in iron - significant to the structure and anisotropy of the Earth's inner core - these have been studied primarily by texture analysis of polycrystalline powders; the convoluted nature of these data, however, render it essentially impossible to examine variant selection, and even precise orientation relationships themselves. Recently developed X-ray diffraction techniques have made it possible to answer these questions. Results from two measurements are presented. First, heterogeneous variant selection was observed and the specific ?/? orientation relationship was determined under quasi-static loading using High Energy Diffraction Microscopy at beamline 1-ID of APS-ANL. Second, the spatial heterogeneity and mutual exclusivity among ? variants was observed at the incipient transition using the Laue ?-diffraction technique at beamline 12.3.2. of ALS-LBNL. In both cases, a 60x25?m single crystal of iron was pressurized in a DAC and measured before and after the ?-? transition at 13GPa. In the HEDM experiment, spatial resolution is sacrificed for domain-averaged orientation and strain resoltuion, making it possible to quantify the magnitude of the applied deviatoric stress in situ. In the Laue ?-Diffraction technique, the local lattice orientations are mapped with 1?m resolution, displaying marked spatial variation. These pilot experiments open new possibilities for investigating high pressure/high temperature transformations in situ. By mapping both orientations and lattice strains, the nature of the mechanisms and driving forces can be illuminated. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Funding through the Laboratory Directed Research and Development program (10- ERD-053) is gratefully acknowledged.

Bernier, J. V.; Barton, N. R.; Farber, D.; Wenk, H.; Kunz, M.; Lienert, U.

2012-12-01

270

Long-term Observations of Electric Field, Temperature, Pressure, Humidity, Wind Speed, Wind Direction, Rainfall Rate and Solar Insolation at a Remote Meteorological Observing Station  

NASA Astrophysics Data System (ADS)

For nearly two years we observed the electric field at the surface continually and simultaneously with observations of temperature, pressure, humidity, wind speed and direction, rainfall rate and solar insolation at a remote automated meteorological observing station in Norman, OK. The electric-field observations were made with electric-field mills that were cycled on every few minutes for a period of about 20 seconds, 24 hours a day, seven days a week for the entire period of time. We observed a number of interesting patterns in the observations, some familiar and some not. For example, monthly averages of the observations often yield Carnegie curves, but not always. We noted what appears to be a sunrise effect on some days. We present a representative sample of the observations.

Gallagher, F. W.; Beasley, W. H.; Bansemer, A. R.; Grimsley, D. L.; Byerley, L. G.

2001-12-01

271

Observational evidence of a wind direction signal in SSM\\/I passive microwave data  

Microsoft Academic Search

Recent experiments have demonstrated that a wind direction signal is apparent in passive microwave brightness temperature measurements of the sea surface. Extensive matches of Special Sensor Microwave Imager (SSM\\/I) brightness temperatures from several Defense Meteorological Satellite Program (DMSP) satellites, with wind direction measurements from both moored buoys and spaceborne scatterometers clearly show directional signals at 19, 37, and 85 GHz

Gary A. Wick; John J. Bates; Chris C. Gottschall

2000-01-01

272

Interaction of hydrogen with metal sulfide catalysts - direct observation of spillover  

SciTech Connect

A combination of controlled-atmosphere electron microscopy and in-situ electron diffraction techniques have been used to study the manner by which certain metal sulfides interact with 0.2 Torr hydrogen. In these experiments single crystal graphite was used as a probe material since its reactivity in both molecular and atomic hydrogen is well characterized. When the metal sulfide was in direct contact or physically separated from the graphite probe, pitting of the basal plane regions was observed even at room temperature. This unusual behavior is believed to result from the action of atomic hydrogen which is produced via reversible dissociation of molecular hydrogen on the metal sulfide particles. These species are extremely reactive towards the [pi]-electrons present on the graphite basal planes and this action leads to the creation of pits. At the low pressures used in this work, it is clear that the atomic species can migrate not only by surface diffusion processes (spillover) but also by transport through the gas phase. 30 refs., 7 figs., 1 tab.

Rodriguez, N.M.; Baker, R.T.K. (Auburn Univ., AL (United States))

1993-04-01

273

Directly Observing the Motion of DNA Molecules near Solid-State Nanopores  

PubMed Central

We investigate the diffusion and the drift motion of ? DNA molecules near solid-state nanopores prior to their translocation though the nanopores using fluorescence microscopy. The radial dependence of the electric field near a nanopore generated by an applied voltage in ionic solution can be estimated quantitatively in 3D by analyzing the motion of negatively charged DNA molecules. We find that the electric field is approximately spherically symmetric around the nanopore under the conditions investigated. In addition, DNA clogging at the nanopore was directly observed. Surprisingly, the probability of the clogging event increases with increasing external bias voltage. We also find that DNA molecules clogging the nanopore reduce the electric field amplitude at the nanopore membrane surface. To better understand these experimental results, analytical method with Ohm’s law and computer simulation with Poisson and Nernst-Planck (PNP) equations are used to calculate the electric field near the nanopore. These results are of great interest in both experimental and theoretical considerations of the motion of DNA molecules near voltage-biased nanopores. These findings will also contribute to the development of solid-state nanopore based DNA sensing devices.

Ando, Genki; Hyun, Changbae; Li, Jiali; Mitsui, Toshiyuki

2012-01-01

274

Direct observation of de-mixing in a ceramic metal-halide arc lamp  

NASA Astrophysics Data System (ADS)

De-mixing of additives in a vertically-operated, ceramic DyI3-CsI-Hg metal-halide arc lamp has been observed by examining the ratios of absolute elemental densities as a function of position. As the elemental densities have been obtained directly by x-ray induced fluorescence (Curry J J, Adler H G, Shastri S D and Lee W-K 2003 J. Appl. Phys. 93 2359), this approach reveals the extent of mixing (or de-mixing) with no intervening assumptions about equilibrium, the local temperature, or the accuracy of partition functions. The metal additives in the arc studied show complex de-mixing. Depletion of Dy and Cs from the core is attributed to ambipolar cataphoresis. These same additives also exhibit a relative enhancement in a layer just outside the core before decreasing again toward the wall. Thermochemical data are used to derive radial distributions of molecular species given the experimentally obtained elemental densities and the gas temperature assuming a lamp operating pressure of 106 Pa (10 atm).

Curry, J. J.; Adler, H. G.; Lee, W.-K.; Shastri, S. D.

2003-07-01

275

Directly observing the motion of DNA molecules near solid-state nanopores.  

PubMed

We investigate the diffusion and the drift motion of ? DNA molecules near solid-state nanopores prior to their translocation through the nanopores using fluorescence microscopy. The radial dependence of the electric field near a nanopore generated by an applied voltage in ionic solution can be estimated quantitatively in 3D by analyzing the motion of negatively charged DNA molecules. We find that the electric field is approximately spherically symmetric around the nanopore under the conditions investigated. In addition, DNA clogging at the nanopore was directly observed. Surprisingly, the probability of the clogging event increases with increasing external bias voltage. We also find that DNA molecules clogging the nanopore reduce the electric field amplitude at the nanopore membrane surface. To better understand these experimental results, analytical method with Ohm's law and computer simulation with Poisson and Nernst-Planck (PNP) equations are used to calculate the electric field near the nanopore. These results are of great interest in both experimental and theoretical considerations of the motion of DNA molecules near voltage-biased nanopores. These findings will also contribute to the development of solid-state nanopore-based DNA sensing devices. PMID:23046052

Ando, Genki; Hyun, Changbae; Li, Jiali; Mitsui, Toshiyuki

2012-11-27

276

Direct observation of turbulent magnetic fields in hot, dense laser produced plasmas.  

PubMed

Turbulence in fluids is a ubiquitous, fascinating, and complex natural phenomenon that is not yet fully understood. Unraveling turbulence in high density, high temperature plasmas is an even bigger challenge because of the importance of electromagnetic forces and the typically violent environments. Fascinating and novel behavior of hot dense matter has so far been only indirectly inferred because of the enormous difficulties of making observations on such matter. Here, we present direct evidence of turbulence in giant magnetic fields created in an overdense, hot plasma by relativistic intensity (10(18) W/cm(2)) femtosecond laser pulses. We have obtained magneto-optic polarigrams at femtosecond time intervals, simultaneously with micrometer spatial resolution. The spatial profiles of the magnetic field show randomness and their k spectra exhibit a power law along with certain well defined peaks at scales shorter than skin depth. Detailed two-dimensional particle-in-cell simulations delineate the underlying interaction between forward currents of relativistic energy "hot" electrons created by the laser pulse and "cold" return currents of thermal electrons induced in the target. Our results are not only fundamentally interesting but should also arouse interest on the role of magnetic turbulence induced resistivity in the context of fast ignition of laser fusion, and the possibility of experimentally simulating such structures with respect to the sun and other stellar environments. PMID:22566660

Mondal, Sudipta; Narayanan, V; Ding, Wen Jun; Lad, Amit D; Hao, Biao; Ahmad, Saima; Wang, Wei Min; Sheng, Zheng Ming; Sengupta, Sudip; Kaw, Predhiman; Das, Amita; Kumar, G Ravindra

2012-05-22

277

Directly observed care: can unannounced standardized patients address a gap in performance measurement?  

PubMed

There are three potential sources of information for evaluating a clinician's performance: documentation, patient report, and directly observed care. Current measures draw on just two of these: data recorded in the medical record and surveys of patients. Neither captures an array of performance characteristics, including clinician attention to symptoms and signs while taking a history or conducting a physical exam, accurate recording in the medical record of information obtained during the encounter, evidence based communication strategies for preventive care counseling, and effective communication behavior. Unannounced Standardized Patients (USPs) have been widely deployed as a research strategy for systematically uncovering significant performance deficits in each of these areas, but have not been adopted for quality improvement. Likely obstacles include concerns about the ethics of sending health professionals sham patients, the technical challenges of the subterfuge, and concerns about the relatively small sample sizes and substantial costs involved. However, the high frequency of significant and remediable performance deficits unmasked by USPs, and the potential to adapt registration and record keeping systems to accommodate their visits, suggest that their selective and purposeful deployment could be a cost effective and powerful strategy for addressing a gap in performance measurement. PMID:24756945

Weiner, Saul J; Schwartz, Alan

2014-08-01

278

Direct spectroscopic observation of ion deceleration accompanying laser plasma-wall interaction  

NASA Astrophysics Data System (ADS)

Interactions of plasma jets with solid surfaces are extensively studied in context with development of future fusion devices. In experiments carried out on the iodine laser system PALS, the energetic ions were produced at double-foil Al/Mg targets irradiated by one or two counter-propagating laser beams. The plasma jets from the rear surface of the laser-exploded Al foil streamed towards the Mg target representing the wall preheated by the action of the high-energy photons, particle and/or laser beams. Instead of being trapped by the cold secondary-target material, the forward-accelerated Al ions collided with the counter-propagating matter ejected from the wall. The environmental conditions in near-wall plasmas were analyzed with the high-resolution x-ray spectroscopy and temporally-resolved x-ray imaging. The deceleration of the incident Al ions in the near-wall region was directly observed and quantitatively characterized via Doppler shifts of the J-satellite from the Al Lya spectral group. The interaction scenario was modelled using the 2D arbitrary Lagrangian Eulerian hydrocode PALE and the multifluid code MULTIF.

Renner, O.; Krouský, E.; Liska, R.; Šmíd, M.; Larroche, O.; Dalimier, E.; Rosmej, F. B.

2010-08-01

279

Direct observation of a reconfigurable graphene p-n junction through surface potential imaging  

NASA Astrophysics Data System (ADS)

Graphene p-n junctions have tremendous potential for future carbon-based electronic devices. Various theoretical models predict that graphene p-n junctions can be configured to guide electrons analogous to an optical wave guide or focus electrons as from a negative index lens, depending on abruptness of the electrostatic doping profile across the p-n junction. In this work, mechanically exfoliated graphene has been deposited on buried split-gate test structures to form pristine graphene p-n junctions not exposed to photoresist or lithographic patterning. An electrostatically formed p-n junction was created on this structure through the application of a voltage differential between the buried `split' gates. Scanning Kelvin Probe Microscopy was used to directly and simultaneously image p-type, n-type and intrinsic regions on the monolayer graphene deposited across the p-n gate structure with nanometer spatial resolution and potential resolution in mV range. The electrostatic doping in graphene is seen to change according to gate polarity when varied from positive to negative values. This observation is reproducible for multiple samples studied. Graphene differential surface potential is measured as a function of split-gate electrode voltage and displays the expected square root behavior. Measurements of the junction profile are also presented and discussed.

Wang, Yunfei; Robinson, Zachary; Lee, Ji Ung; Geer, Robert E.

2010-03-01

280

Direct observation of turbulent magnetic fields in hot, dense laser produced plasmas  

PubMed Central

Turbulence in fluids is a ubiquitous, fascinating, and complex natural phenomenon that is not yet fully understood. Unraveling turbulence in high density, high temperature plasmas is an even bigger challenge because of the importance of electromagnetic forces and the typically violent environments. Fascinating and novel behavior of hot dense matter has so far been only indirectly inferred because of the enormous difficulties of making observations on such matter. Here, we present direct evidence of turbulence in giant magnetic fields created in an overdense, hot plasma by relativistic intensity (1018W/cm2) femtosecond laser pulses. We have obtained magneto-optic polarigrams at femtosecond time intervals, simultaneously with micrometer spatial resolution. The spatial profiles of the magnetic field show randomness and their k spectra exhibit a power law along with certain well defined peaks at scales shorter than skin depth. Detailed two-dimensional particle-in-cell simulations delineate the underlying interaction between forward currents of relativistic energy “hot” electrons created by the laser pulse and “cold” return currents of thermal electrons induced in the target. Our results are not only fundamentally interesting but should also arouse interest on the role of magnetic turbulence induced resistivity in the context of fast ignition of laser fusion, and the possibility of experimentally simulating such structures with respect to the sun and other stellar environments.

Mondal, Sudipta; Narayanan, V.; Ding, Wen Jun; Lad, Amit D.; Hao, Biao; Ahmad, Saima; Wang, Wei Min; Sheng, Zheng Ming; Sengupta, Sudip; Kaw, Predhiman; Das, Amita; Kumar, G. Ravindra

2012-01-01

281

Direct observation of crystal growth from solution using optical investigation of a growing crystal face  

NASA Technical Reports Server (NTRS)

The first technical report for the period 1 Jan. 1993 till 31 Dec. 1993 for the research entitled, 'Direct observation of crystal growth from solution using Optical Investigation of a growing crystal Face' is presented. The work on the project did not start till 1 June 1993 due to the non-availability of the required personnel. The progress of the work during the period 1 June 1993 till the end of 1993 is described. Significant progress was made for testing various optical diagnostic techniques for monitoring crystal solution. Some of the techniques that are being tested are: heterodyne detection technique, in which changes in phase are measured as a interferometric function of time/crystal growth; a conventional technique, in which a fringe brightness is measured as a function of crystal growth/time; and a Mach-Zehnder interferometric technique in which a fringe brightness is measured as a function of time to obtain information on concentration changes. During the second year it will be decided to incorporate the best interferometric technique along with the ellipsometric technique, to obtain real time in-situ growth rate measurements. A laboratory mock-up of the first two techniques were made and tested.

Lal, Ravindra

1994-01-01

282

Direct Observation of Strand Passage by DNA-Topoisomerase and Its Limited Processivity  

PubMed Central

Type-II DNA topoisomerases resolve DNA entanglements such as supercoils, knots and catenanes by passing one segment of DNA duplex through a transient enzyme-bridged double-stranded break in another segment. The ATP-dependent passage reaction has previously been demonstrated at the single-molecule level, showing apparent processivity at saturating ATP. Here we directly observed the strand passage by human topoisomerase II?, after winding a pair of fluorescently stained DNA molecules with optical tweezers for 30 turns into an X-shaped braid. On average 0.51±0.33 µm (11±6 turns) of a braid was unlinked in a burst of reactions taking 8±4 s, the unlinked length being essentially independent of the enzyme concentration between 0.25–37 pM. The time elapsed before the start of processive unlinking decreased with the enzyme concentration, being ?100 s at 3.7 pM. These results are consistent with a scenario where the enzyme binds to one DNA for a period of ?10 s, waiting for multiple diffusional encounters with the other DNA to transport it across the break ?10 times, and then dissociates from the binding site without waiting for the exhaustion of transportable DNA segments.

Yogo, Katsunori; Ogawa, Taisaku; Hayashi, Masahito; Harada, Yoshie; Nishizaka, Takayuki; Kinosita, Kazuhiko

2012-01-01

283

Direct real-space observation of nearly stochastic behavior in magnetization reversal process on a nanoscale  

SciTech Connect

We report a non-deterministic nature in the magnetization reversal of nanograins of CoCrPt alloy film. Magnetization reversal process of CoCrPt alloy film is investigated using high resolution soft X-ray microscopy which provides real space images with a spatial resolution of 15 nm. Domain nucleation sites mostly appear stochastically distributed within repeated hysteretic cycles, where the correlation increases as the strength of the applied magnetic field increases in the descending and ascending branches of the major hysteresis loop. In addition, domain configuration is mostly asymmetric with inversion of an applied magnetic field in the hysteretic cycle. Nanomagnetic simulation considering thermal fluctuations of the magnetic moments of the grains explains the nearly stochastic nature of the domain nucleation behavior observed in CoCrPt alloy film. With the bit size in high-density magnetic recording media approaching nanometer length scale, one of the fundamental and crucial issues is whether the domain nucleation during magnetization reversal process exhibits a deterministic behavior. Repeatability of local domain nucleation and deterministic switching behavior are basic and essential factors for achieving high performance in high-density magnetic recording [1-3]. Most experimental studies on this issue reported so far have been mainly performed by indirect probes through macroscopic hysteresis loop and Barkhausen pattern measurements, which provide the ensemble-average magnetization. Thus, they are inadequate to gain insight into the domain-nucleation behavior on a nanometer length scale during the magnetization reversal process [4-6]. Very recently, coherent X-ray speckle metrology, where the speckle pattern observed in reciprocal space acts as a fingerprint of the domain configurations, was adopted to investigate stochastic behavior in the magnetization reversal of a Co/Pt multilayer film [7,8]. However, no direct observation on the stochastic behavior of domain nucleation during magnetization reversal in real space at the nanometer scale has yet been reported. The main reason is due to limitations of the microscopic measurement techniques employed. Thus, experimental confirmation for stochastic behavior of domain nucleation together with its clarification has to date remained a scientific challenge.

Im, M.-Y.; Kim, D.-H.; Lee, K.-D.; Fischer, P.; Shin, S.-C.

2007-06-01

284

5 CFR 180.104 - Allowable claims.  

Code of Federal Regulations, 2010 CFR

...allowed for damage to or loss of property as a direct consequence of: (i) Enemy action or threat thereof, or combat, guerilla, brigandage, or other belligerent activity, or unjust confiscation by a foreign power or its nationals; (ii)...

2010-01-01

285

5 CFR 180.104 - Allowable claims.  

Code of Federal Regulations, 2010 CFR

...allowed for damage to or loss of property as a direct consequence of: (i) Enemy action or threat thereof, or combat, guerilla, brigandage, or other belligerent activity, or unjust confiscation by a foreign power or its nationals; (ii)...

2009-01-01

286

44 CFR 206.228 - Allowable costs.  

Code of Federal Regulations, 2013 CFR

General policies for determining allowable costs are established in 44 CFR 13.22. Exceptions to those policies as allowed in 44 CFR 13.4 and 13.6 are explained below. (a) Eligible direct costs â(1) Applicant-owned...

2013-10-01

287

The Photochemical Reflectance Index from Directional Cornfield Reflectances: Observations and Simulations  

NASA Technical Reports Server (NTRS)

The two-layer Markov chain Analytical Canopy Reflectance Model (ACRM) was linked with in situ hyperspectral leaf optical properties to simulate the Photochemical Reflectance Index (PRI) for a corn crop canopy at three different growth stages. This is an extended study after a successful demonstration of PRI simulations for a cornfield previously conducted at an early vegetative growth stage. Consistent with previous in situ studies, sunlit leaves exhibited lower PRI values than shaded leaves. Since sunlit (shaded) foliage dominates the canopy in the reflectance hotspot (coldspot), the canopy PRI derived from field hyperspectral observations displayed sensitivity to both view zenith angle and relative azimuth angle at all growth stages. Consequently, sunlit and shaded canopy sectors were most differentiated when viewed along the azimuth matching the solar principal plane. These directional PRI responses associated with sunlit/shaded foliage were successfully reproduced by the ACRM. As before, the simulated PRI values from the current study were closer to in situ values when both sunlit and shaded leaves were utilized as model input data in a two-layer mode, instead of a one-layer mode with sunlit leaves only. Model performance as judged by correlation between in situ and simulated values was strongest for the mature corn crop (r = 0.87, RMSE = 0.0048), followed by the early vegetative stage (r = 0.78; RMSE = 0.0051) and the early senescent stage (r = 0.65; RMSE = 0.0104). Since the benefit of including shaded leaves in the scheme varied across different growth stages, a further analysis was conducted to investigate how variable fractions of sunlit/shaded leaves affect the canopy PRI values expected for a cornfield, with implications for 20 remote sensing monitoring options. Simulations of the sunlit to shaded canopy ratio near 50/50 +/- 10 (e.g., 60/40) matching field observations at all growth stages were examined. Our results suggest in the importance of the sunlit/shaded fraction and canopy structure in understanding and interpreting PRI.

Cheng, Yen-Ben; Middleton, Elizabeth M.; Zhang, Qingyuan; Corp, Lawrence A.; Dandois, Jonathan; Kustas, William P.

2012-01-01

288

Lattice Boltzmann simulation and direct observation of pore fluid flow around irregularly shaped grains  

NASA Astrophysics Data System (ADS)

An accurate velocity model of porous flow plays an important role in the prediction of the ground water pollution.To clarify the behavior of porous flow passing through irregularly shaped grains, we have been performed CFD simulation and direct observation based on the Lattice Boltzmann Method and the LAT-PIV visuallization technique respectively. The Lattice Boltzmann simulator, which works on a graphics processing unit(GPU), is employed to evaluate the pore fluid velocity distribution in an accurate three dimensional digital model involving Toyoura sand. From the simulation results, the pore fluid velocity distributions converge into a unique non-gaussian distribution under various Reynolds numbers ranging from 2 to 10. The features of the non-gaussian distribution are summarized as follows: (1)It has a long tail until sextuple of the mean velocity magnitude. (2)It has a peak frequency close to zero velocity magnitude. (3)It slightly contains negative velocities. The LAT-PIV visuallization technique, a kind of laser slicing visualization method combined LAT(Laser-Aided Tomography) and PIV (Particle Image Velocimetry), visualizes both grain edges and pore fluid behavior inside specimen which is composed of crashed glass grains and specially blended silicone oil. The pore fluid velocity distributions captured by the LAT-PIV images indicate a similar tendency compared with those measured by the LBM simulations. This supports that the LBM simulation has sufficient ability to predict the pore fluid flow even if the porous medium is composed of irregularly shaped grains. GPU accelerated LBM simulation for Toyoura sand model Pore fluid velocity magnitude distributions for several Reynolds numbers

Saomoto, H.; Kase, Y.; Matsushima, T.; Yamada, Y.

2012-12-01

289

Direct Observation of Individual KCNQ1 Potassium Channels Reveals Their Distinctive Diffusive Behavior*  

PubMed Central

We have directly observed the trafficking and fusion of ion channel containing vesicles and monitored the release of individual ion channels at the plasma membrane of live mammalian cells using total internal reflection fluorescence microscopy. Proteins were fused in-frame with green or red fluorescent proteins and expressed at low level in HL-1 and HEK293 cells. Dual color imaging revealed that vesicle trafficking involved motorized movement along microtubules followed by stalling, fusion, and subsequent release of individual ion channels at the plasma membrane. We found that KCNQ1-KCNE1 complexes were released in batches of about 5 molecules per vesicle. To elucidate the properties of ion channel complexes at the cell membrane we tracked the movement of individual molecules and compared the diffusive behavior of two types of potassium channel complex (KCNQ1-KCNE1 and Kir6.2-SUR2A) to that of a G-protein coupled receptor, the A1 adenosine receptor. Plots of mean squared displacement against time intervals showed that mobility depended on channel type, cell type, and temperature. Analysis of the mobility of wild type KCNQ1-KCNE1 complexes showed the existence of a significant immobile subpopulation and also a significant number of molecules that demonstrated periodic stalling of diffusive movements. This behavior was enhanced in cells treated with jasplakinolide and was abrogated in a C-terminal truncated form (KCNQ1(R518X)-KCNE1) of the protein. This mutant has been identified in patients with the long QT syndrome. We propose that KCNQ1-KCNE1 complexes interact intermittently with the actin cytoskeleton via the C-terminal region and this interaction may have a functional role.

Mashanov, Gregory I.; Nobles, Muriel; Harmer, Stephen C.; Molloy, Justin E.; Tinker, Andrew

2010-01-01

290

A Comparison of Modified Directly Observed Therapy to Standard Care for Chronic Hepatitis C  

PubMed Central

Hepatitis C virus (HCV) is the most common chronic blood-borne infection in the United States. Effective treatments are available, however adherence to treatment is challenging. Modified directly observed therapy (mDOT) with weekly administration of pegylated interferon might improve adherence and outcomes for patients infected with chronic HCV. To compare two treatment protocols and examine predictors of sustained virologic response (SVR). A retrospective review comparing chronic HCV treatment outcomes in two outpatient clinics at an urban academic medical center. Gastroenterology fellows provided standard treatment (SC) in one clinic; a nurse practitioner administered weekly pegylated interferon injections weekly in a primary care clinic. All patients received oral ribavirin. Data was extracted from the medical records of all treated patients over a 5-year period. 155 treatment-naïve, chronically infected HCV patients were treated. Ninety-seven patients received mDOT treatment and 58 received standard care. Mean age was 46 years. Genotype 1 represented 59 % of the sample. The mDOT patients were significantly more likely to be younger (44 vs. 50 years), have a history of injection drug use (93.1 vs. 50.0 %), and be HIV-infected (13.5 vs. 2 %) compared to SC patients. The overall SVR rate was 45.2 % and did not differ between the groups in unadjusted analyses (p = 0.95). Genotype was the only predictor of SVR. Patients treated by nurse practitioners trained in HCV care and seen weekly for interferon injections have comparable treatment outcomes to patients treated by specialists.

Stein, Michael D.; Promrat, Kittichai; Friedmann, Peter D.

2013-01-01

291

Randomized Control Trial of Peer-Delivered, Modified Directly Observed Therapy for HAART in Mozambique  

PubMed Central

Objective To assess the efficacy of a peer-delivered intervention to promote short-term (6-month) and long-term (12-month) adherence to HAART in a Mozambican clinic population. Design A 2-arm randomized controlled trial was conducted between October 2004 and June 2006. Participants Of 350 men and women (?18 years) initiating HAART, 53.7% were female, and 97% were on 1 fixed-dose combination pill twice a day. Intervention Participants were randomly assigned to receive 6 weeks (Monday through Friday; 30 daily visits) of peer-delivered, modified directly observed therapy (mDOT) or standard care. Peers provided education about treatment and adherence and sought to identify and mitigate adherence barriers. Outcome Participants' self-reported medication adherence was assessed 6 months and 12 months after starting HAART. Adherence was defined as the proportion of prescribed doses taken over the previous 7 days. Statistical analyses were performed using intention-to-treat (missing = failure). Results Intervention participants, compared to those in standard care, showed significantly higher mean medication adherence at 6 months (92.7% vs. 84.9%, difference 7.8, 95% confidence interval [CI]: 0.0.02, 13.0) and 12 months (94.4% vs. 87.7%, difference 6.8, 95% CI: 0.9, 12.9). There were no between-arm differences in chart-abstracted CD4 counts. Conclusions A peer-delivered mDOT program may be an effective strategy to promote long-term adherence among persons initiating HAART in resource-poor settings.

Pearson, Cynthia R.; Micek, Mark A.; Simoni, Jane M.; Hoff, Peter D.; Matediana, Eduardo; Martin, Diane P.; Gloyd, Stephen S.

2014-01-01

292

Direct observation of alumina nanowire formation from porous anodic alumina membrane via the droplet etching method  

NASA Astrophysics Data System (ADS)

We report the first direct observation of the formation process of an alumina nanowire (ANW) array from a porous anodic alumina (PAA) membrane employing a simple droplet etching method, not a general immersion etching method, using field emission scanning electron spectroscopy (FESEM). The PAA membrane is prepared by the two-step anodization method and subsequent lift-off process. The surface view SEM images of the PAA membrane show an array of highly ordered hexagonal pore distribution within the domains of 1-2 µm size, which are separated from neighbouring domains with different orientations of the pore lattice by grain boundaries. The FESEM analysis of the formation process of the alumina nanowire reveals that the formation process consists of three critical steps. The first step involves an image revealing that the outer parts of pore walls are dissolved. The image can be described by the different etching rates of oxide layers in the PAA membrane. Differences in the etching rate can be explained in terms of the different anion impurity concentration in the oxide layer of the PAA membrane. The second step produces an image of the PAA membrane with triangular triple points, surrounded by three adjacent pores. This image can be interpreted as the combined effects of the thickness difference of pore walls and the thermal annealing of the PAA membrane. The last step shows images where the triangular cross section ANWs transform into circular cross section ones as further etching occurs. This can result from the crystallization of the triple points during the annealing process.

Kim, J.; Choi, Y. C.; Chang, K.-S.; Bu, S. D.

2006-01-01

293

Direct observations of muscle arterioles and venules following contraction of skeletal muscle fibres in the rat.  

PubMed Central

Direct observations have been made of responses of individual arterioles and venules of rat spinotrapezius muscle to contraction of the skeletal muscle fibres. Stimuli of 4-6 V intensity, 0.1 ms duration, delivered via a micro-electrode inserted into the spinotrapezius, evoked contraction of a small bundle of skeletal muscle fibres, followed by vasodilatation which was limited to all those arterioles and venules which crossed or ran alongside activated muscle fibres. Since venules outside the region of contraction, but supplied by dilating arterioles, were not passively distended by the attendant rise in intravascular pressure, it is concluded that both the arterioles and venules dilated actively in response to muscle contraction. All arterioles responded to a single twitch contraction, the terminal arterioles (7-13 micron i.d.) showing the largest increase in diameter. Collecting venules (9-18 micron i.d.) responded to just two twitches in 1 s and larger venules to five twitches in 1 s. When twitch contractions were continuously evoked for 10 s, the responses in individual arterioles and venules were graded with twitch frequency, the fastest and largest response occurring at 6-8 Hz. Tetanic contraction, at 40 Hz for 1 s, produced faster responses in all vessels, a maximum 55% increase from resting internal diameter being attained in only 8 s in some terminal arterioles. In all vessels the responses to tetanic contraction were equal to the maximal dilatation induced by papaverine. These results, in contrast with conclusions drawn from indirect estimates of venous responses, show that venules, like arterioles, dilate actively in response to muscle contraction. Venule dilatation may reduce the rise in capillary hydrostatic pressure, thereby limiting the outward filtration of fluid.

Marshall, J M; Tandon, H C

1984-01-01

294

Observation of direct photons in central 158A GeV (208)P(208)b+Pb collisions  

PubMed

A measurement of direct photon production in 208Pb+208Pb collisions at 158A GeV has been carried out in the CERN WA98 experiment. The invariant yield of direct photons in central collisions is extracted as a function of transverse momentum in the interval 0.5direct photon signal, compared to statistical and systematical errors, is seen at p(T)>1.5 GeV/c. The result constitutes the first observation of direct photons in ultrarelativistic heavy-ion collisions. It could be significant for diagnosis of quark-gluon-plasma formation. PMID:11030959

Nikolaev; Nilsson; Nishimura; Nomokonov; Nystrand; Obenshain; Oskarsson; Otterlund; Pachr; Pavliouk; Peitzmann; Petracek; Pinganaud; Plasil; Poblotzki; Purschke; Rak; Raniwala; Raniwala; Ramamurthy; Rao; Retiere; Reygers; Roland; Rosselet; Roufanov

2000-10-23

295

Observation of Direct Photons in Central 158A GeV 208P208b+Pb Collisions  

NASA Astrophysics Data System (ADS)

A measurement of direct photon production in 208Pb+208Pb collisions at 158A GeV has been carried out in the CERN WA98 experiment. The invariant yield of direct photons in central collisions is extracted as a function of transverse momentum in the interval 0.5direct photon signal, compared to statistical and systematical errors, is seen at pT>1.5 GeV/c. The result constitutes the first observation of direct photons in ultrarelativistic heavy-ion collisions. It could be significant for diagnosis of quark-gluon-plasma formation.

Aggarwal, M. M.; Agnihotri, A.; Ahammed, Z.; Angelis, A. L.; Antonenko, V.; Arefiev, V.; Astakhov, V.; Avdeitchikov, V.; Awes, T. C.; Baba, P. V.; Badyal, S. K.; Barlag, C.; Bathe, S.; Batiounia, B.; Bernier, T.; Bhalla, K. B.; Bhatia, V. S.; Blume, C.; Bock, R.; Bohne, E.-M.; Böröcz, Z.; Bucher, D.; Buijs, A.; Büsching, H.; Carlen, L.; Chalyshev, V.; Chattopadhyay, S.; Cherbatchev, R.; Chujo, T.; Claussen, A.; Das, A. C.; Decowski, M. P.; Delagrange, H.; Djordjadze, V.; Donni, P.; Doubovik, I.; Dutt, S.; Dutta Majumdar, M. R.; El Chenawi, K.; Eliseev, S.; Enosawa, K.; Foka, P.; Fokin, S.; Ganti, M. S.; Garpman, S.; Gavrishchuk, O.; Geurts, F. J.; Ghosh, T. K.; Glasow, R.; Gupta, S. K.; Guskov, B.; Gustafsson, H. Å.; Gutbrod, H. H.; Higuchi, R.; Hrivnacova, I.; Ippolitov, M.; Kalechofsky, H.; Kamermans, R.; Kampert, K.-H.; Karadjev, K.; Karpio, K.; Kato, S.; Kees, S.; Klein-Bösing, C.; Knoche, S.; Kolb, B. W.; Kosarev, I.; Koutcheryaev, I.; Krümpel, T.; Kugler, A.; Kulinich, P.; Kurata, M.; Kurita, K.; Kuzmin, N.; Langbein, I.; Lebedev, A.; Lee, Y. Y.; Löhner, H.; Luquin, L.; Mahapatra, D. P.; Manko, V.; Martin, M.; Martínez, G.; Maximov, A.; Mgebrichvili, G.; Miake, Y.; Mir, Md. F.; Mishra, G. C.; Miyamoto, Y.; Mohanty, B.; Mora, M.-J.; Morrison, D.; Mukhopadhyay, D. S.; Naef, H.; Nandi, B. K.; Nayak, S. K.; Nayak, T. K.; Neumaier, S.; Nianine, A.; Nikitine, V.; Nikolaev, S.; Nilsson, P.; Nishimura, S.; Nomokonov, P.; Nystrand, J.; Obenshain, F. E.; Oskarsson, A.; Otterlund, I.; Pachr, M.; Pavliouk, S.; Peitzmann, T.; Petracek, V.; Pinganaud, W.; Plasil, F.; Poblotzki, U. V.; Purschke, M. L.; Rak, J.; Raniwala, R.; Raniwala, S.; Ramamurthy, V. S.; Rao, N. K.; Retiere, F.; Reygers, K.; Roland, G.; Rosselet, L.; Roufanov, I.; Roy, C.; Rubio, J. M.; Sako, H.; Sambyal, S. S.; Santo, R.; Sato, S.; Schlagheck, H.; Schmidt, H.-R.; Schutz, Y.; Shabratova, G.; Shah, T. H.; Sibiriak, I.; Siemiarczuk, T.; Silvermyr, D.; Sinha, B. C.; Slavine, N.; Söderström, K.; Solomey, N.; Sood, G.; Sørensen, S. P.; Stankus, P.; Stefanek, G.; Steinberg, P.; Stenlund, E.; Stüken, D.; Sumbera, M.; Svensson, T.; Trivedi, M. D.; Tsvetkov, A.; Tykarski, L.; Urbahn, J.; Pijll, E. C.; Eijndhoven, N. V.; Nieuwenhuizen, G. J.; Vinogradov, A.; Viyogi, Y. P.; Vodopianov, A.; Vörös, S.; Wys?ouch, B.; Yagi, K.; Yokota, Y.; Young, G. R.

2000-10-01

296

Adverse Reactions Due to Directly Observed Treatment Strategy Therapy in Chinese Tuberculosis Patients: A Prospective Study  

PubMed Central

Background More than 1 million tuberculosis (TB) patients are receiving directly observed treatment strategy (DOTS) therapy in China every year. As to the profile of adverse drug reactions (ADRs) due to DOTS therapy, no consensus has been reached. There is no report regarding ADRs due to DOTS therapy with a large Chinese TB population. This study aimed to determine the incidence and prognosis of ADRs due to DOTS therapy, and to evaluate their impact on anti-TB treatment in China. Methods A prospective population-based cohort study was performed during 2007–2008. Sputum smear positive pulmonary TB patients who received DOTS therapy were included and followed up for six to nine months in 52 counties of four regions in China. The suspected ADRs were recorded and reviewed by Chinese State Food and Drug Administration. Results A total of 4304 TB patients were included in this study. 649 patients (15.08%) showed at least one ADR and 766 cases in total were detected. The incidence (count) of ADR based on affected organ was: liver dysfunction 6.34% (273), gastrointestinal disorders 3.74% (161), arthralgia 2.51% (108), allergic reactions 2.35% (101), neurological system disorders 2.04% (88), renal impairment 0.07% (3) and others 0.05% (2). Most cases of ADRs (95%) had a good clinical outcome, while two with hepatotoxicity and one with renal impairment died. Compared with patients without ADRs, patients with ADRs were more likely to have positive smear test results at the end of the intensive phase (adjusted OR, 2.00; 95%CI, 1.44–2.78) and unsuccessful anti-TB outcomes (adjusted OR, 2.58; 95%CI, 1.43–4.68). Conclusions The incidence of ADRs due to DOTS therapy was 15.08%. Those ADRs had a substantial impact on TB control in China. This highlighted the importance of developing strategies to ameliorate ADRs both to improve the quality of patient care and to control TB safely.

Lv, Xiaozhen; Tang, Shaowen; Xia, Yinyin; Wang, Xiaomeng; Yuan, Yanli; Hu, Daiyu; Liu, Feiying; Wu, Shanshan; Zhang, Yuan; Yang, Zhirong; Tu, Dehua; Chen, Yixin; Deng, Peiyuan; Ma, Yu; Chen, Ru; Zhan, Siyan

2013-01-01

297

The Directly Observed Therapy Short-Course (DOTS) strategy in Samara Oblast, Russian Federation  

PubMed Central

Background The World Health Organisation (WHO) defines Russia as one of the 22 highest-burden countries for tuberculosis (TB). The WHO Directly Observed Treatment Short Course (DOTS) strategy employing a standardised treatment for 6 months produces the highest cure rates for drug sensitive TB. The Russian TB service traditionally employed individualised treatment. The purpose of this study was to implement a DOTS programme in the civilian and prison sectors of Samara Region of Russia, describe the clinical features and outcomes of recruited patients, determine the proportion of individuals in the cohorts who were infected with drug resistant TB, the degree to which resistance was attributed to the Beijing TB strain family and establish risk factors for drug resistance. Methods prospective study Results 2,099 patients were recruited overall. Treatment outcomes were analysed for patients recruited up to the third quarter of 2003 (n = 920). 75.3% of patients were successfully treated. Unsuccessful outcomes occurred in 7.3% of cases; 3.6% of patients died during treatment, with a significantly higher proportion of smear-positive cases dying compared to smear-negative cases. 14.0% were lost and transferred out. A high proportion of new cases (948 sequential culture-proven TB cases) had tuberculosis that was resistant to first-line drugs; (24.9% isoniazid resistant; 20.3% rifampicin resistant; 17.3% multidrug resistant tuberculosis). Molecular epidemiological analysis demonstrated that half of all isolated strains (50.7%; 375/740) belonged to the Beijing family. Drug resistance including MDR TB was strongly associated with infection with the Beijing strain (for MDR TB, 35.2% in Beijing strains versus 9.5% in non-Beijing strains, OR-5.2. Risk factors for multidrug resistant tuberculosis were: being a prisoner (OR 4.4), having a relapse of tuberculosis (OR 3.5), being infected with a Beijing family TB strain (OR 6.5) and having an unsuccessful outcome from treatment (OR 5.0). Conclusion The implementation of DOTS in Samara, Russia, was feasible and successful. Drug resistant tuberculosis rates in new cases were high and challenge successful outcomes from a conventional DOTS programme alone.

Balabanova, Y; Drobniewski, F; Fedorin, I; Zakharova, S; Nikolayevskyy, V; Atun, R; Coker, R

2006-01-01

298

Direct observation of subtropical mode water circulation in the western North Atlantic Ocean  

NASA Astrophysics Data System (ADS)

Eighteen Degree Water (EDW) is the dominant subtropical mode water of the North Atlantic subtropical gyre and is hypothesized as an interannual reservoir of anomalous heat, nutrients and CO2. Although isolated beneath the stratified upper-ocean at the end of each winter, EDW may re-emerge in subsequent years to influence mixed layer properties and consequently air-sea interaction and primary productivity. Here we report on recent quasi-Lagrangian measurements of EDW circulation and stratification in the western subtropical gyre using an array of acoustically-tracked, isotherm-following, bobbing profiling floats programmed to track and intensively sample the vertically homogenized EDW layer and directly measure velocity on the 18.5 °C isothermal surface. The majority of the CLIVAR Mode Water Dynamics Experiment (CLIMODE) bobbers drifted within the subtropical gyre for 2.5-3.5 years, many exhibiting complex looping patterns indicative of an energetic eddy field. Bobber-derived Lagrangian integral time and length scales (3 days, 68 km) associated with motion on 18.5 °C were consistent with previous measurements in the Gulf Stream extension region and fall between previous estimates at the ocean surface and thermocline depth. Several bobbers provided evidence of long-lived submesoscale coherent vortices associated with substantial EDW thickness. While the relative importance of such vortices remains to be determined, our observations indicate that these features can have a profound effect on EDW distribution. EDW thickness (defined using a vertical temperature gradient criterion) exhibits seasonal changes in opposition to a layer bounded by the 17 °C and 19 °C isotherms. In particular, EDW thickness is generally greatest in winter (as a result of buoyancy-forced convection), while the 17°-19 °C layer is thickest in summer consistent with seasonal Ekman pumping. Contrary to previous hypotheses, the bobber data suggest that a substantial fraction of subducted EDW is isolated from the atmosphere for periods of less than 24 months. Seasonal-to-biennial re-emergence (principally within the recirculation region south of the Gulf Stream) appears to be a common scenario which should be considered when assessing the climatic and biogeochemical consequences of EDW.

Fratantoni, David M.; Kwon, Young-Oh; Hodges, Benjamin A.

2013-07-01

299

Direct constraint on the distance of gamma2 Velorum from AMBER\\/VLTI observations  

Microsoft Academic Search

Context: Interferometry can provide spatially resolved observations of massive star binary systems and their colliding winds, which thus far have been studied mostly with spatially unresolved observations. Aims: We present the first AMBER\\/VLTI observations, taken at orbital phase 0.32, of the Wolf-Rayet and O (WR+O) star binary system gamma2 Velorum and use the interferometric observables to constrain its properties. Methods:

F. Millour; R. G. Petrov; O. Chesneau; D. Bonneau; L. Dessart; C. Bechet; I. Tallon-Bosc; M. Tallon; E. Thiébaut; F. Vakili; F. Malbet; D. Mourard; P. Antonelli; U. Beckmann; Y. Bresson; A. Chelli; M. Dugué; G. Duvert; S. Gennari; L. Glück; P. Kern; S. Lagarde; E. Le Coarer; F. Lisi; K. Perraut; P. Puget; F. Rantakyrö; S. Robbe-Dubois; A. Roussel; E. Tatulli; G. Weigelt; G. Zins; M. Accardo; B. Acke; K. Agabi; E. Altariba; B. Arezki; E. Aristidi; C. Baffa; J. Behrend; T. Blöcker; S. Bonhomme; S. Busoni; F. Cassaing; J.-M. Clausse; J. Colin; C. Connot; A. Delboulbé; A. Domiciano de Souza; T. Driebe; P. Feautrier; D. Ferruzzi; T. Forveille; E. Fossat; R. Foy; D. Fraix-Burnet; A. Gallardo; E. Giani; C. Gil; A. Glentzlin; M. Heiden; M. Heininger; O. Hernandez Utrera; K.-H. Hofmann; D. Kamm; M. Kiekebusch; S. Kraus; D. Le Contel; J.-M. Le Contel; T. Lesourd; B. Lopez; M. Lopez; Y. Magnard; A. Marconi; G. Mars; G. Martinot-Lagarde; P. Mathias; P. Mège; J.-L. Monin; D. Mouillet; E. Nussbaum; K. Ohnaka; J. Pacheco; C. Perrier; Y. Rabbia; S. Rebattu; F. Reynaud; A. Richichi; A. Robini; M. Sacchettini; D. Schertl; M. Schöller; W. Solscheid; A. Spang; P. Stee; P. Stefanini; D. Tasso; L. Testi; O. von der Lühe; J.-C. Valtier; M. Vannier; N. Ventura

2007-01-01

300

The Biasing Effects of Labels on Direct Observation by Preservice Teachers  

ERIC Educational Resources Information Center

Observational bias can significantly affect results attained through observation. This study focused on 122 preservice teacher educators who conducted a structured observation, using momentary time sampling procedures with 10-second intervals, to measure student on-task and off-task behaviors. The experimental variable altered was the…

Allday, R. Allan; Duhon, Gary J.; Blackburn-Ellis, Sarah; Van Dycke, Jamie L.

2011-01-01

301

49 CFR 40.67 - When and how is a directly observed collection conducted?  

Code of Federal Regulations, 2013 CFR

...FOR TRANSPORTATION WORKPLACE DRUG AND ALCOHOL TESTING PROGRAMS Urine Specimen Collections § 40.67 When and how is a directly...the collection container. Specifically, you are to watch the urine go from the employee's body into the collection...

2013-10-01

302

Direct Observation of Oil Consumption Mechanisms in a Production Spark Ignition Engine Using Fluorescence Techniques.  

National Technical Information Service (NTIS)

The oil consumption characteristics of a four cylinder, normally aspirated spark-ignition engine were investigated for different piston ring end-gap configurations. A radiotracer was used to perform direct measurement of the oil consumption while Laser-in...

R. M. Lusted

1994-01-01

303

Direct observation of stimulated-Brillouin-scattering detuning by a velocity gradient.  

PubMed

We report the first direct evidence of detuning of stimulated Brillouin scattering (SBS) by a velocity gradient, which was achieved by directly measuring the frequency shift of the SBS-driven acoustic wave relative to the local resonant acoustic frequency. We show that in the expanding part of the plasma, ion-acoustic waves are driven off resonance which leads to the saturation of the SBS instability. These measurements are well reproduced by fluid simulations that include the measured flow. PMID:12732042

Froula, D H; Divol, L; MacKinnon, A; Gregori, G; Glenzer, S H

2003-04-18

304

Microscopic Observations on the Origin of Defects During Machining of Direct Aged (DA) Inconel 718 Superalloy  

Microsoft Academic Search

Surface quality of advanced superalloys after machining is one of the major issues in the aerospace industry because it directly\\u000a affects service characteristics of the machined part. Tool life of cemented carbide inserts with the TiAlN coating during\\u000a machining of direct aged DA 718 alloys under roughing and finishing conditions has been under study. The defect origin on\\u000a the surface

G. K. Dosbaeva; S. C. Veldhuis; A. Elfizy; G. Fox-Rabinovich; T. Wagg

2010-01-01

305

Observations on direct and cross tolerance with LSD and d-amphetamine in man  

Microsoft Academic Search

1.Within the limits of this experimental design in man:a)the spectrum of LSD effects is different from that of d-amphetamine in single doses to nontolerant subjectsb)following the daily administration of LSD for 14 days, direct tolerance develops to LSD (1.5 mcg\\/kg) with respect to pupillary dilatation and mental excitationc)following the daily administration of d-amphetamine for 14 days, direct tolerance develops to

D. E. Rosenberg; A. B. Wolbach; E. J. Miner; Harris Isbell

1963-01-01

306

Observations of Surface Wave Azimuthal Anisotropy in Southern California by Direct Application of the Beamforming Method  

NASA Astrophysics Data System (ADS)

We use the Southern California Seismic Network as an array and apply a beamforming method for 190 teleseismic events to determine their Rayleigh surface wave phase velocities and their arrival directions. Our results indicate that the array aperture has excellent resolution for periods 16-100 seconds but above 100 seconds phase velocities begin to show large error bars because of its spatial size. We recover the ubiquitous pattern of azimuthal phase velocity variation of Rayleigh waves for periods 16-50 seconds; the amplitude variations are about 1-1.5%, consistent with an assumption of a weakly anisotropic medium. Our results also confirm an assumption in most studies, of negligible dependence on the 4-theta component. Though these results apply only in Southern California, direct confirmation of small 4-theta variations seems to be rare. Our analysis shows that anisotropy is present in the period range 15-50 seconds which correspond approximately to 50-200 km wavelengths, and suggests anisotropy extends to the upper mantle with an prevalent anisotropic fast axis that is oriented along the direction SE-NW (110/290 degrees clockwise from North). This direction is interesting in that it is sub-parallel with the Mohave section of the San Andreas Fault. It is this section of the fault that is misaligned with the general direction of the North America-Pacific Plate boundary. Thus we speculate that the fast axis alignment may be associated with shear and compression of the Transverse Ranges.

Alvizuri, C. R.; Tanimoto, T.

2010-12-01

307

Spectroscopic observation of simultaneous bi-directional reconnection outflows in a laboratory plasma  

SciTech Connect

We report a precise, direct spectroscopic measurement of simultaneous bi-directional outflows from a reconnection event in a laboratory plasma. Outflow speeds are as Alfvenic and Abel analysis shows that the outflows are generated in the plasma core. A Sweet-Parker like analysis of outflow speed coupled with external measurements of reconnection electric field and assumption of Spitzer resistivity predict an aspect ratio of the reconnection layer and reconnection rate that are close to that measured in the experiment and in simulations. However, this analysis underestimates the absolute scale of the layer, indicating other than 2D resistive physics is at play.

Brown, M. R.; Cothran, C. D.; Gray, T. [Department of Physics and Astronomy, Center for Magnetic Self Organization, Swarthmore College, Swarthmore, Pennsylvania 19081-1397 (United States); Myers, C. E.; Belova, E. V. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2012-08-15

308

Direct Observations of Children at Risk for Academic Failure: Benefits of an Intergenerational Visiting Program  

ERIC Educational Resources Information Center

Ten elementary school students in need of a positive self-image and/or a sense of appropriate social conduct took part in a monthly intergenerational visiting program at an assisted living facility. In comparison to systematic observations obtained in their classrooms, the children were observed to be significantly less anxious, more interested,…

Marx, Marcia, S.; Pannell, Alicia, R.; Parpura-Gill, Aleksandra; Cohen-Mansfield, Jiska

2004-01-01

309

Saturation of wave-packet interferences: Direct observation of spin precession in potassium atoms  

Microsoft Academic Search

A sequence of two identical ultrashort laser pulses creates quantum interferences in an atom. In the weak-field regime, the observed beats between interferences arising from various transitions are not a conclusive signature of wave-packet creation. On the contrary, in the saturation regime, the appearance of slow modulation is. We report on the observation of such modulations in atomic potassium in

Céline Nicole; Mohamed Aziz Bouchene; Sébastien Zamith; Noureddine Melikechi; Bertrand Girard

1999-01-01

310

Direct observation of electron-transfer-induced conformational transformation (molecular actuation) in a bichromophoric electron donor.  

PubMed

With the aid of laser-flash photolysis, the one-electron oxidation of conformationally mobile tetramethoxydibenzobicyclo[4.4.1]undecane (1), using photoexcited chloranil as an oxidant, allows us to show that extended 1(+•) undergoes a conformational transformation to ?-stacked folded 1(+•) on a microsecond time scale (? ? 1 ?s), which is at least six times longer than that found for the conformationally locked model compound. PMID:20491456

Shukla, Ruchi; Thakur, Khushabu; Chebny, Vincent J; Reid, Scott A; Rathore, Rajendra

2010-11-18

311

Observation of a time modulated muon flux in the direction of Cygnus X-3  

Microsoft Academic Search

The analysis of angular and phase distribution is reported for high energy muons recorded in the NUSEX nucleon decay detector, located in the Mont Blanc tunnel at a depth of about 5000 hg of standard rock. Evidence is found for a signal correlated to the direction and time modulation of Cygnus X-3.

G. Battistoni; E. Bellotti; C. Bloise; G. Bologna; P. Campana; C. Castagnoli; A. Castellina; V. Chiarella; A. Ciocio; Donald C Cundy; B. D'Ettorre-Piazzoli; Ettore Fiorini; P. Galeotti; Enzo Iarocci; C. Liguori; G. Mannocchi; G P Murtas; P. Negri; G. Nicoletti; P. Picchi; M. Price; Antonio Pullia; S. Ragazzi; M. Rollier; O. Saavedra; L. Satta; P. Serri; S. Vernetto; L. Zanotti

1985-01-01

312

Participant observation of time allocation, direct patient contact and simultaneous activities in hospital physicians  

Microsoft Academic Search

BACKGROUND: Hospital physicians' time is a critical resource in medical care. Two aspects are of interest. First, the time spent in direct patient contact – a key principle of effective medical care. Second, simultaneous task performance ('multitasking') which may contribute to medical error, impaired safety behaviour, and stress. There is a call for instruments to assess these aspects. A preliminary

Matthias Weigl; Andreas Müller; Andrea Zupanc; Peter Angerer

2009-01-01

313

Direct Behavior Rating (DBR): Generalizability and Dependability across Raters and Observations  

ERIC Educational Resources Information Center

Generalizability theory was used to examine the generalizability and dependability of outcomes from two single-item Direct Behavior Rating (DBR) scales: DBR of actively manipulating and DBR of visually distracted. DBR is a behavioral assessment tool with specific instrumentation and procedures that can be used by a variety of service delivery…

Christ, Theodore J.; Riley-Tillman, T. Chris; Chafouleas, Sandra M.; Boice, Christina H.

2010-01-01

314

Intracoronary ultrasound imaging before and after directional coronary atherectomy: In vitro and clinical observations  

Microsoft Academic Search

The rate of restenosis after directional coronary atherectomy (DCA) is higher than expected. To elucidate why, the current study used intravascular ultrasound (IVUS) imaging to investigate the mechanism of DCA. An in vitro validation study was performed to determine the accuracy of the measurement of plaque removal by IVUS. DCA was performed in eight human atherosclerotic artery segments. The volume

Shigeru Nakamura; Donald J. Mahon; Cyril Y. Leung; Bavani Maheswaran; Dan E. Gutfinger; Jenchen Yang; Robert Zelman; Jonathan M. Tobis

1995-01-01

315

Direct observation of the ice rule in an artificial kagome spin ice  

Microsoft Academic Search

Recently, significant interest has emerged in fabricated systems that mimic the behavior of geometrically frustrated materials. We present the full realization of such an artificial spin ice system on a two-dimensional kagome lattice and we demonstrate rigid adherence to the local ice rule by directly counting individual pseudospins. The resulting spin configurations show not only local ice rules and long-range

Yi Qi; T. Brintlinger; John Cumings

2008-01-01

316

Direct Observation of Multiphoton Processes in Laser-Induced Free-Free Transitions  

Microsoft Academic Search

Multiphoton processes are detected in the scattering of electrons on argon atoms in the presence of a strong CO2-laser field. The observations are in accordance with a recently developed semiclassical model.

A. Weingartshofer; J. K. Holmes; G. Caudle; E. M. Clarke; H. Krueger

1977-01-01

317

Species dependent energies in upward directed ion beams over auroral arcs as observed with FAST TEAMS  

NASA Astrophysics Data System (ADS)

Upward flowing field-aligned ion beams over auroral arcs have been observed with the 3-dimensional ion mass spectrograph TEAMS on FAST. We have performed a statistical study on a sample of 77 ion beams from the auroral campaign in early 1997. All observed beams contain substantial amounts of H+, He+ and O+. A clear ordering of the total energies according to mass is found, with H+ having the lowest and O+ the highest energy. The composition varies significantly from beam to beam, with O+/H+ ratios ranging from ? 0.1 to 10. No variation of the energy ratio between species is observed as a function of relative abundance. These results are discussed in the light of earlier observations of higher energies for O+ in statistical studies of beams during solar minimum and attempts to explain this behavior in terms of beam instabilities.

Möbius, E.; Tang, L.; Kistler, L. M.; Popecki, M.; Lund, E. J.; Klumpar, D.; Peterson, W.; Shelley, E. G.; Klecker, B.; Hovestadt, D.; Carlson, C. W.; Ergun, R.; McFadden, J. P.; Mozer, F.; Temerin, M.; Cattell, C.; Elphic, R.; Strangeway, R.; Pfaff, R.

318

DIRECT OBSERVATION OF THE TURBULENT emf AND TRANSPORT OF MAGNETIC FIELD IN A LIQUID SODIUM EXPERIMENT  

SciTech Connect

For the first time, we have directly measured the transport of a vector magnetic field by isotropic turbulence in a high Reynolds number liquid metal flow. In analogy with direct measurements of the turbulent Reynolds stress (turbulent viscosity) that governs momentum transport, we have measured the turbulent electromotive force (emf) by simultaneously measuring three components of velocity and magnetic fields, and computed the correlations that lead to mean-field current generation. Furthermore, we show that this turbulent emf tends to oppose and cancel out the local current, acting to increase the effective resistivity of the medium, i.e., it acts as an enhanced magnetic diffusivity. This has important implications for turbulent transport in astrophysical objects, particularly in dynamos and accretion disks.

Rahbarnia, Kian; Brown, Benjamin P.; Clark, Mike M.; Kaplan, Elliot J.; Nornberg, Mark D.; Rasmus, Alex M.; Taylor, Nicholas Zane; Forest, Cary B. [Department of Physics, University of Wisconsin-Madison, 1150 University Ave, Madison, WI 53706 (United States); Jenko, Frank; Limone, Angelo [Max-Planck-Institut fuer Plasmaphysik (IPP), EURATOM Association, D-85748 Garching (Germany); Pinton, Jean-Francois; Plihon, Nicolas; Verhille, Gautier, E-mail: kian.rahbarnia@ipp.mpg.de [Laboratoire de Physique de l'Ecole Normale Superieure de Lyon, CNRS and Universite de Lyon, F-69364 Lyon (France)

2012-11-10

319

Direct observation of the behavior of heavy single atoms on amorphous carbon substrates  

NASA Astrophysics Data System (ADS)

Using a scanning transmission electron microscope it is possible, by directly imaging single atoms, to investigate the motion and distribution of heavy (high-Z) atoms deposited on the surfaces of thin low-Z films. In this study, the heavy atoms U, Pt, Au, In, Cd, Ag, and Pd were deposited on 15-Å-thick amorphous carbon substrates. It is found that adatom motion is strongly dependent upon local substrate structure and adatom species. Diffusion coefficients and activation energies for single atoms, as well as dimers, trimers, etc., have been obtained by directly measuring the motion of the atoms. Pair-density and nearest-neighbor distributions were measured and used to derive the interatomic potential and the rate of adatom nucleation. It is found that the interatomic potential is very weak and long ranged.

Utlaut, M.

1980-11-01

320

Direct Observation of the Turbulent emf and Transport of Magnetic Field in a Liquid Sodium Experiment  

NASA Astrophysics Data System (ADS)

For the first time, we have directly measured the transport of a vector magnetic field by isotropic turbulence in a high Reynolds number liquid metal flow. In analogy with direct measurements of the turbulent Reynolds stress (turbulent viscosity) that governs momentum transport, we have measured the turbulent electromotive force (emf) by simultaneously measuring three components of velocity and magnetic fields, and computed the correlations that lead to mean-field current generation. Furthermore, we show that this turbulent emf tends to oppose and cancel out the local current, acting to increase the effective resistivity of the medium, i.e., it acts as an enhanced magnetic diffusivity. This has important implications for turbulent transport in astrophysical objects, particularly in dynamos and accretion disks.

Rahbarnia, Kian; Brown, Benjamin P.; Clark, Mike M.; Kaplan, Elliot J.; Nornberg, Mark D.; Rasmus, Alex M.; Zane Taylor, Nicholas; Forest, Cary B.; Jenko, Frank; Limone, Angelo; Pinton, Jean-François; Plihon, Nicolas; Verhille, Gautier

2012-11-01

321

Barkhausen noise measurements give direct observation of magnetocrystalline anisotropy energy in ferromagnetic polycrystals  

NASA Astrophysics Data System (ADS)

This paper presents experimental evidence of the capability of Barkhausen noise measurements to estimate the angular dependence of the average magnetocrystalline energy in soft magnetic polycrystalline materials. Three different API 5L steel samples, all obtained from out-of-service pipelines, were investigated using crystallographic texture and Barkhausen noise measurements. The angular dependence of the rms voltage of the Barkhausen signal was determined in each sample for the time band corresponding to the saturation-to-remanence part of the hysteresis loop where irreversible domain rotation occurs. For each angular position, the rms voltage of the Barkhausen noise signal in this time band was interpreted as a direct measure of the magnetocrystalline anisotropy energy of the polycrystal in the corresponding direction. A strong correlation between the angular dependence of both the rms voltage of the Barkhausen signal in the time band of interest and the average magnetocrystalline energy obtained from crystallographic texture measurements was found experimentally.

Espina-Hernández, J. H.; Pérez-Benítez, J. A.; Caleyo, F.; Baudin, T.; Helbert, A. L.; Hallen, J. M.

2013-10-01

322

Direct observation of vortex shells and magic numbers in mesoscopic superconducting disks.  

PubMed

We have studied vortex configurations in mesoscopic superconducting disks using the Bitter decoration technique. For a broad range of vorticities L the circular geometry is found to lead to the formation of concentric shells of vortices. From images obtained on disks of different sizes in a range of magnetic fields we traced the evolution of vortex states and identified stable and metastable configurations of interacting vortices. Furthermore, the analysis of shell filling with increasing L allowed us to identify magic numbers corresponding to the appearance of consecutive new shells. PMID:16606130

Grigorieva, I V; Escoffier, W; Richardson, J; Vinnikov, L Y; Dubonos, S; Oboznov, V

2006-02-24

323

Establishing the Feasibility of Direct Observation in the Assessment of Tics in Children with Chronic Tic Disorders  

ERIC Educational Resources Information Center

Behavior analysis has been at the forefront in establishing effective treatments for children and adults with chronic tic disorders. As is customary in behavior analysis, the efficacy of these treatments has been established using direct-observation assessment methods. Although behavior-analytic treatments have enjoyed acceptance and integration…

Himle, Michael B.; Chang, Susanna; Woods, Douglas W.; Pearlman, Amanda; Buzzella, Brian; Bunaciu, Liviu; Piacentini, John C.

2006-01-01

324

Local observations of fast ion responses to energetic particle modes using a directional probe in the Compact Helical System (CHS)  

Microsoft Academic Search

Bursting energetic particle mode (EPM) and fast ion loss induced by the EPM have been observed and experimentally investigated in the Compact Helical System (CHS). A directional probe method was newly applied to neutral beam heated plasmas for fast ion measurement, and it successfully revealed fast ion behaviour inside the last closed flux surface (LCFS) during bursting EPMs. A convective

K. Nagaoka; M. Isobe; K. Toi; K. Goto; T. Ito; Y. Todo; M. Osakabe; S. Ohshima; A. Shimizu; A. Fujisawa; H. Nakano; Y. Takeiri; K. Y. Watanabe; T. Akiyama; Y. Yoshimura; C. Suzuki; S. Nishimura; K. Matsuoka; S. Okamura

2008-01-01

325

Direct Observation as a Decision Method for Evaluating Inclusionary Classroom Participation of Children with Mild Hearing Impairment: A Pilot Study  

ERIC Educational Resources Information Center

An observation code was utilized to study how children with mild to moderate hearing loss participate within inclusive classroom settings. Participation was considered as active engagement as well as following routines and directions. Prevalence of behavior, responses to practice and prompt opportunities, levels of prompting required to follow…

Borders, Christina Marie

2009-01-01

326

Bi-directional streaming of halo electrons in interplanetary plasma clouds observed between 0.3 and 1 AU  

NASA Technical Reports Server (NTRS)

The solar wind data obtained from the two Helios solar probes in the years 1974 to 1986 were systematically searched for the occurrence of bi-directional electron events. Most often these events are found in conjunction with shock associated magnetic clouds. The implications of these observations for the topology of interplanetary plasma clouds are discussed.

Ivory, K.; Schwenn, R.

1995-01-01

327

A fishery-independent assessment of an overfished rockfish stock, cowcod ( Sebastes levis ), using direct observations from an occupied submersible  

Microsoft Academic Search

A meaningful assessment of cowcod (Sebastes levis) has been conducted using visual, nonextractive, habitat- specific methods. Following the precipitous decline of rockfish (Sebastes spp.) stocks along the Pacific coast, it was evident that more effective methods were needed to assess several species in untrawlable habitats. Cowcod were surveyed within large Cowcod Conservation Areas (CCAs) off southern California using direct observations

Mary M. Yoklavich; Milton S. Love; Karin A. Forney

2007-01-01

328

Direct spectroscopic observation of charge-exchange recombination of medium-Z elements in the PLT tokamak  

SciTech Connect

We report the first observation of line emission resulting directly from charge-exchange recombination of medium-Z elements (Al, Sc) injected into a PLT discharge. Transitions due to the radiative cascade immediately following charge-exchange of He-like Al and Sc were observed by a VUV spectrograph and two air monochromators. In two cases, AlXI 3209 A and ScXIX 112.1 A, the observed transition had not previously been experimentally identified. Spatial scans provided information on the profile of the neutral beam in the plasma.

Skinner, C.H.; Suckewer, S.; Cohen, S.A.; Schilling, G.; Wilson, R.; Stratton, B.

1984-03-01

329

Direct observations of sigma phase growth and dissolution in 2205 duplex stainless steel  

SciTech Connect

The formation and growth of sigma ({sigma}) phase in a 2205 duplex stainless steel is monitored during an 850 C isothermal heat treatment using an in situ synchrotron x-ray diffraction technique. At this temperature, {sigma} phase is first observed within approximately 40 seconds of the start of the isothermal heat treatment and grows rapidly over the course of the 3600 second heat treatment to a volume fraction of approximately 13%. A simultaneous increase in the austenite ({gamma}) volume fraction and a decrease in the ferrite ({delta}) volume fraction are observed. The {sigma} phase formed at this temperature is rapidly dissolved within approximately 200 seconds when the temperature is increased to 1000 C. Accompanying this rapid dissolution of the {sigma} phase, the {delta} and {gamma} volume fractions both approach the balanced (50/50) level observed in the as-received material.

Palmer, T.A.; Elmer, J.W.; Babu, S.S.; Specht, E.D. (LLNL); (ORNL)

2007-10-10

330

Direct Observation of a Nuclear Spin Excitation in Ho2Ti2O7  

SciTech Connect

A single nondispersive excitation is observed by means of neutron backscattering, at E{sub 0} = 26.3 {micro}eV in the spin ice Ho{sub 2}Ti{sub 2}O{sub 7} but not in the isotopically enriched {sup 162}Dy{sub 2}Ti{sub 2}O{sub 7} analogue. The intensity of this excitation is rather small, {approx}< 0.2% of the elastic intensity. It is clearly observed below 80 K but resolution limited only below {approx}65 K. The application of a magnetic field up to {mu}{sub 0}H = 4.5 T, at 1.6 K, has no measurable effect on the energy or intensity. This nuclear excitation is believed to perturb the electronic, Ising spin system resulting in the persistent spin dynamics observed in spin ice compounds.

Ehlers, Georg [ORNL; Mamontov, Eugene [ORNL; Zamponi, Michaela M [ORNL

2009-01-01

331

Direct observation of a nuclear spin excitation in Ho2Ti2O7.  

PubMed

A single nondispersive excitation is observed by means of neutron backscattering, at E_{0}=26.3 microeV in the spin ice Ho2Ti2O7 but not in the isotopically enriched 162Dy2Ti2O7 analogue. The intensity of this excitation is rather small, less, similar0.2% of the elastic intensity. It is clearly observed below 80 K but resolution limited only below approximately 65 K. The application of a magnetic field up to micro_{0}H=4.5 T, at 1.6 K, has no measurable effect on the energy or intensity. This nuclear excitation is believed to perturb the electronic, Ising spin system resulting in the persistent spin dynamics observed in spin ice compounds. PMID:19257221

Ehlers, G; Mamontov, E; Zamponi, M; Kam, K C; Gardner, J S

2009-01-01

332

Direct and remotely-sensed observations of water vapor isotopes in the North American Monsoon domain  

NASA Astrophysics Data System (ADS)

The climate models that make up the current IPCC ensemble do not accurately represent the predominant spatial and temporal features of the North American Monsoon (NAM) system. This leads to large uncertainty in predicting the response of the NAM to both anthropogenic and natural forcings. One method of diagnosing model deficiencies in capturing summertime precipitation patterns in the Southwestern US is to assess how the atmospheric moisture budget of a model compares to observed budgets created using water isotope data. We present an analysis of continuous in situ ground and tower-based observations of the isotopic composition of water vapor (?D and ?18O) and remotely-sensed satellite retrievals of the column-integrated isotopic composition of water vapor (?D) from the Greenhouse Gases Observing Satellite over the southwestern US. The isotopic data capture a strong seasonal transition between winter and summer seasons, which is associated with a change between predominately northwesterly and southwesterly moisture sources. On synoptic timescales during the monsoon season, the isotopes also serve as a lucid tracer of "Gulf Surges" providing observational confirmation on the importance of this moisture source; a finding that had previously been gleaned through "painted water" simulations and wind pattern analysis. While Gulf Surges are observable from analysis of water vapor concentration alone, observations of the isotopic composition of this phenomenon provides a unique capacity to trace the northerly extent of this moisture, which is difficult to discern from looking at non-isotopic humidity data alone. The new data also show that from a budgetary standpoint the significance of continental moisture fluxes (evaporation and transpiration) is quite large. This result therefore suggests that progress on modeling the NAM and ultimately in understandings its response to forcing cannot only be focused on large-scale SST and atmospheric circulation fields but also must better address the surface moisture dynamics and land-atmosphere coupling.

Berkelhammer, M. B.; Langford, S.; Buenning, N. H.; Yoshimura, K.; Frankenberg, C.; Kaushik, A.; Noone, D. C.

2012-12-01

333

A DTN-ready application for the real-time dissemination of Earth Observation data received by Direct Readout stations  

NASA Astrophysics Data System (ADS)

The majority of Earth observation satellites operate in low Earth sun-synchronous orbit and transmit data captured by a variety of sensors. The effective dissemination of satellite data in real-time is a crucial parameter for disaster monitoring in particular. Generally, a spacecraft collects data and then stores it on-board until it passes over dedicated ground stations to transmit the data. Additionally, some satellites (e.g. Terra, Aqua, Suomi-NPP, NOAA series satellites) have the so-called Direct Broadcast (DB) capability, which is based on a real-time data transmission sub-system. Compatible Direct Readout (DR) stations in direct line of sight are able to receive these transmissions. To date data exchange between DR stations have not been fully exploited for real-time data dissemination. Stations around the world store data locally, which is then disseminated on demand via Internet gateways based on the standard TCP-IP protocols. On the other hand, Delay Tolerant Networks (DTNs), which deliver data by enabling store-and-forward transmission in order to cope with link failures, service disruptions and network congestion, could prove as an alternative/complementary transmission mechanism for the efficient dissemination of data. The DTN architecture allows for efficient utilization of the network, using in-network storage and taking advantage of the network availability among the interconnected nodes. Although DTNs were originally developed for high-propagation delay, challenged connectivity environments such as deep space, the broader research community has investigated possible architectural enhancements for various emerging applications (e.g., terrestrial infrastructure, ground-to-air communications, content retrieval and dissemination). In this paper, a scheme for the effective dissemination of DB data is conceptualized, designed and implemented based on store-and-forward transmission capabilities provided by DTNs. For demonstration purposes, a set-up has been designed and implemented which emulates the interconnection and data transmission of various HRPT/AVHRR DR stations based on pre-scheduled contacts via the DTN architecture. According to the scheme adopted, as soon as the satellite scans the earth and after image reception, a contact is established with a DTN node and data transmission is initiated. These DR stations form a DTN overlay, taking advantage of the routing, transport and security mechanisms developed. Most importantly, data received at a station can automatically be forwarded to any other station belonging to the same "interest" group through a flexible DTN multicasting mechanism. Thus, a composite image of an extended area (or potentially an image of the entire globe, depending on the interest groups formed is constructed in each node in an imperceptible way. Upon processing of the received data streams, stations are able to further disseminate new products to other interested third party entities exploiting the DTN overlay and the filtering capabilities provided by a web-based tool. The work leading to this paper has received funding from the European Union's Seventh Framework Programme (FP7-SPACE-2010-1) under grant agreement no. 263330 for the SDR (Space-Data Routers for Exploiting Space Data) collaborative research project. This paper reflects only the authors' views and the Union is not liable for any use that may be made of the information contained therein.

Paronis, Dimitris; Daglis, Ioannis A.; Diamantopoulos, Sotirios; Tsaoussidis, Vassilis; Tsigkanos, Antonis; Ghita, Bogdan; Evans, Michael

2014-05-01

334

Direct observations of confined layer slip in Cu/Nb multilayers.  

PubMed

In situ nanoindentation of a 30 nm Cu/20 nm Nb multilayer film in a transmission electron microscope revealed confined layer slip as the dominant deformation mechanism. Dislocations were observed to nucleate from the Cu-Nb interfaces in both layers. Dislocation glide was confined by interfaces to occur within each layer, without transmission across interfaces. Cu and Nb layers co-deformed to large plastic strains without cracking. These microscopy observations provide insights in the unit mechanisms of deformation, work hardening, and recovery in nanoscale metallic multilayers. PMID:23072907

Li, Nan; Wang, Jian; Misra, Amit; Huang, Jian Yu

2012-10-01

335

Direct constraint on the distance of ?2 Velorum from AMBER/VLTI observations  

NASA Astrophysics Data System (ADS)

Context: Interferometry can provide spatially resolved observations of massive star binary systems and their colliding winds, which thus far have been studied mostly with spatially unresolved observations. Aims: We present the first AMBER/VLTI observations, taken at orbital phase 0.32, of the Wolf-Rayet and O (WR+O) star binary system ?2 Velorum and use the interferometric observables to constrain its properties. Methods: The AMBER/VLTI instrument was used with the telescopes UT2, UT3, and UT4 on baselines ranging from 46 m to 85 m. It delivered spectrally dispersed visibilities, as well as differential and closure phases, with a resolution R=1500 in the spectral band 1.95-2.17 ?m. We interpret these data in the context of a binary system with unresolved components, neglecting in a first approximation the wind-wind collision zone flux contribution. Results: Using WR- and O-star synthetic spectra, we show that the AMBER/VLTI observables result primarily from the contribution of the individual components of the WR+O binary system. We discuss several interpretations of the residuals, and speculate on the detection of an additional continuum component, originating from the free-free emission associated with the wind-wind collision zone (WWCZ), and contributing at most to the observed K-band flux at the 5% level. Based on the accurate spectroscopic orbit and the Hipparcos distance, the expected absolute separation and position angle at the time of observations were 5.1±0.9 mas and 66±15°, respectively. However, using theoretical estimates for the spatial extent of both continuum and line emission from each component, we infer a separation of 3.62+0.11-0.30 mas and a position angle of 73+9-11°, compatible with the expected one. Our analysis thus implies that the binary system lies at a distance of 368+38-13 pc, in agreement with recent spectrophotometric estimates, but significantly larger than the Hipparcos value of 258+41-31 pc. Based on observations collected at the European Southern Observatory, Paranal, Chile, within the guaranteed time programme 074.A-9025(A).

Millour, F.; Petrov, R. G.; Chesneau, O.; Bonneau, D.; Dessart, L.; Bechet, C.; Tallon-Bosc, I.; Tallon, M.; Thiébaut, E.; Vakili, F.; Malbet, F.; Mourard, D.; Antonelli, P.; Beckmann, U.; Bresson, Y.; Chelli, A.; Dugué, M.; Duvert, G.; Gennari, S.; Glück, L.; Kern, P.; Lagarde, S.; Le Coarer, E.; Lisi, F.; Perraut, K.; Puget, P.; Rantakyrö, F.; Robbe-Dubois, S.; Roussel, A.; Tatulli, E.; Weigelt, G.; Zins, G.; Accardo, M.; Acke, B.; Agabi, K.; Altariba, E.; Arezki, B.; Aristidi, E.; Baffa, C.; Behrend, J.; Blöcker, T.; Bonhomme, S.; Busoni, S.; Cassaing, F.; Clausse, J.-M.; Colin, J.; Connot, C.; Delboulbé, A.; Domiciano de Souza, A.; Driebe, T.; Feautrier, P.; Ferruzzi, D.; Forveille, T.; Fossat, E.; Foy, R.; Fraix-Burnet, D.; Gallardo, A.; Giani, E.; Gil, C.; Glentzlin, A.; Heiden, M.; Heininger, M.; Hernandez Utrera, O.; Hofmann, K.-H.; Kamm, D.; Kiekebusch, M.; Kraus, S.; Le Contel, D.; Le Contel, J.-M.; Lesourd, T.; Lopez, B.; Lopez, M.; Magnard, Y.; Marconi, A.; Mars, G.; Martinot-Lagarde, G.; Mathias, P.; Mège, P.; Monin, J.-L.; Mouillet, D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.; Perrier, C.; Rabbia, Y.; Rebattu, S.; Reynaud, F.; Richichi, A.; Robini, A.; Sacchettini, M.; Schertl, D.; Schöller, M.; Solscheid, W.; Spang, A.; Stee, P.; Stefanini, P.; Tasso, D.; Testi, L.; von der Lühe, O.; Valtier, J.-C.; Vannier, M.; Ventura, N.

2007-03-01

336

Direct observation of parallel folding pathways revealed using a symmetric repeat protein system.  

PubMed

Although progress has been made to determine the native fold of a polypeptide from its primary structure, the diversity of pathways that connect the unfolded and folded states has not been adequately explored. Theoretical and computational studies predict that proteins fold through parallel pathways on funneled energy landscapes, although experimental detection of pathway diversity has been challenging. Here, we exploit the high translational symmetry and the direct length variation afforded by linear repeat proteins to directly detect folding through parallel pathways. By comparing folding rates of consensus ankyrin repeat proteins (CARPs), we find a clear increase in folding rates with increasing size and repeat number, although the size of the transition states (estimated from denaturant sensitivity) remains unchanged. The increase in folding rate with chain length, as opposed to a decrease expected from typical models for globular proteins, is a clear demonstration of parallel pathways. This conclusion is not dependent on extensive curve-fitting or structural perturbation of protein structure. By globally fitting a simple parallel-Ising pathway model, we have directly measured nucleation and propagation rates in protein folding, and have quantified the fluxes along each path, providing a detailed energy landscape for folding. This finding of parallel pathways differs from results from kinetic studies of repeat-proteins composed of sequence-variable repeats, where modest repeat-to-repeat energy variation coalesces folding into a single, dominant channel. Thus, for globular proteins, which have much higher variation in local structure and topology, parallel pathways are expected to be the exception rather than the rule. PMID:24988356

Aksel, Tural; Barrick, Doug

2014-07-01

337

Direct observation of band bending in the topological insulator Bi2Se3  

NASA Astrophysics Data System (ADS)

The surface band bending tunes considerably the surface band structures and transport properties in topological insulators. We present a direct measurement of the band bending on the Bi2Se3 by using the bulk sensitive angular-resolved hard x-ray photospectroscopy (HAXPES). We tracked the depth dependence of the energy shift of Bi and Se core states. We estimate that the band bending extends up to about 20 nm into the bulk with an amplitude of 0.23-0.26 eV, consistent with profiles previously deduced from the binding energies of surface states in this material.

ViolBarbosa, C. E.; Shekhar, Chandra; Yan, Binghai; Ouardi, S.; Ikenaga, Eiji; Fecher, G. H.; Felser, C.

2013-11-01

338

Direct Observation and Calipering of the {open_quotes}Webbing{close_quotes} Fermi Surface of Yttrium  

SciTech Connect

The first measurement of both the size and shape of the region of the Fermi surface of yttrium known as the {open_quotes}webbing{close_quotes} is reported. This particular Fermi surface feature is of considerable interest because it is very similar to that found in a number of the heavier rare earth metals, where it is believed to play a vital role in driving the exotic magnetic structures found therein. In this positron study, two-dimensional angular correlation measurements combined with three-dimensional reconstruction provide a direct image of this part of the yttrium Fermi surface. {copyright} {ital 1997} {ital The American Physical Society}

Dugdale, S.B.; Fretwell, H.M.; Alam, M.A. [H.H.Wills Physics Laboratory, University of Bristol,Tyndall Avenue, Bristol, BS8 1TL (United Kingdom)] [H.H.Wills Physics Laboratory, University of Bristol,Tyndall Avenue, Bristol, BS8 1TL (United Kingdom); Kontrym-Sznajd, G. [Polish Academy of Sciences, W. Trzebiatowski Intsitute of Low Temperature and Structure Research, 50-950 Wroclaw 2, P.O.Box 937 (Poland)] [Polish Academy of Sciences, W. Trzebiatowski Intsitute of Low Temperature and Structure Research, 50-950 Wroclaw 2, P.O.Box 937 (Poland); West, R.N.; Badrzadeh, S. [Department of Physics, University of Texas at Arlington, P.O.Box 19059, Arlington, Texas 76019 (United States)] [Department of Physics, University of Texas at Arlington, P.O.Box 19059, Arlington, Texas 76019 (United States)

1997-08-01

339

Direct observation of magnetically induced phase separation in Co-W sputtered thin films  

NASA Astrophysics Data System (ADS)

Phase separation of Co-W sputtered thin films having a large magnetocrystalline anisotropy energy have been investigated. A nanoscale compositional fluctuation caused by magnetically induced phase separation was directly confirmed in the films deposited on a heated substrate in analogy with Co-Cr-based alloys. The difference between the phase separation features in Co-W and Co-Cr is attributed to the difference in their elastic energy. It is expected that the phase separation is enhanced by selecting optimum sputtering conditions. The Co-W system, therefore, is considered to be a promising candidate as a base alloy system for high-density recording media.

Oikawa, K.; Qin, G. W.; Sato, M.; Okamoto, S.; Kitakami, O.; Shimada, Y.; Fukamichi, K.; Ishida, K.; Koyama, T.

2004-09-01

340

Parent Information and Direct Observation in the Diagnosis of Pervasive and Specific Developmental Disorders.  

ERIC Educational Resources Information Center

An Autism Diagnostic Interview (ADI-R) was conducted with parents of 11 children with early infantile autism and 16 with a language disorder, along with a standardized Autism Diagnostic Observation Schedule (ADOS-G). Ten children with autism were correctly classified on both measures. One child with a language disorder was falsely classified on…

Noterdaeme, Michele; Mildenberger, Katrin; Sitter, Stefan; Amorosa, Hedwig

2002-01-01

341

Mid-depth recirculation observed in the interior Labrador and Irminger seas by direct velocity measurements  

Microsoft Academic Search

The Labrador Sea is one of the sites where convection exports surface water to the deep ocean in winter as part of the thermohaline circulation. Labrador Sea water is characteristically cold and fresh, and it can be traced at intermediate depths (500-2,000m) across the North Atlantic Ocean, to the south and to the east of the Labrador Sea. Widespread observations

Kara L. Lavender; Russ E. Davis; W. Brechner Owens

2000-01-01

342

Value-Directed Human Behavior Analysis from Video Using Partially Observable Markov Decision Processes  

Microsoft Academic Search

This paper presents a method for learning decision theoretic models of human behaviors from video data. Our system learns relationships between the movements of a person, the context in which they are acting, and a utility function. This learning makes explicit that the meaning of a behavior to an observer is contained in its relationship to actions and outcomes. An

Jesse Hoey; James J. Little

2007-01-01

343

The direct observations of large aerosol radiative forcing in the Himalayan region  

Microsoft Academic Search

We show here that absorbing aerosols have led to a large reduction of surface solar radiation during winter over the Himalayan region. Our results are based on radiometric, aerosol and Lidar observations made at three sites in Nepal during winter 2003. The monthly mean aerosol optical depth (AOD) ranged from 0.2 to 0.34 and the TERRA satellite MODIS data reveal

M. V. Ramana; V. Ramanathan; I. A. Podgorny; Bidya B. Pradhan; Basanta Shrestha

2004-01-01

344

New Directions in Earth Observing: Scientific Applications of Multiangle Remote Sensing  

Microsoft Academic Search

The physical interpretation of simultaneous multiangle observations represents a relatively new approach to remote sensing of terrestrial geophysical and biophysical parameters. Multiangle measurements enable retrieval of physical scene characteristics, such as aerosol type, cloud morphology and height, and land cover (e.g., vegetation canopy type), providing improved albedo accuracies as well as compositional, morphological, and structural information that facilitates addressing many

David J. Diner; Gregory P. Asner; Roger Davies; Yuri Knyazikhin; Jan-Peter Muller; Anne W. Nolin; Bernard Pinty; Crystal B. Schaaf; Julienne Stroeve

1999-01-01

345

Direct Observation of a Sharp Transition to Coherence in Dense Cores  

NASA Astrophysics Data System (ADS)

We present NH3 observations of the B5 region in Perseus obtained with the Green Bank Telescope. The map covers a region large enough (~11'×14') that it contains the entire dense core observed in previous dust continuum surveys. The dense gas traced by NH3(1,1) covers a much larger area than the dust continuum features found in bolometer observations. The velocity dispersion in the central region of the core is small, presenting subsonic non-thermal motions which are independent of scale. However, it is because of the coverage and high sensitivity of the observations that we present the detection, for the first time, of the transition between the coherent core and the dense but more turbulent gas surrounding it. This transition is sharp, increasing the velocity dispersion by a factor of 2 in less than 0.04 pc (the 31'' beam size at the distance of Perseus, ~250 pc). The change in velocity dispersion at the transition is ?3 km s-1 pc-1. The existence of the transition provides a natural definition of dense core: the region with nearly constant subsonic non-thermal velocity dispersion. From the analysis presented here, we can neither confirm nor rule out a corresponding sharp density transition.

Pineda, Jaime E.; Goodman, Alyssa A.; Arce, Héctor G.; Caselli, Paola; Foster, Jonathan B.; Myers, Philip C.; Rosolowsky, Erik W.

2010-03-01

346

Direct Observation of the Intersection of Sequence Faults in the Fe-Cr sigma-Phase  

Microsoft Academic Search

The intersection of two sequence faults perpendicular to each other was observed by lattice images in transmission electron microscopy. Structural models near the intersections were obtained on the assumption that the atoms are arranged in a similar manner to the regular sigma-phase structure even in the faulted region. Two kinds of characteristic arrangements have been confirmed at the intersections. One

Tsutomu Ishimasa; Yasuyuki Kitano; Yukitomo Komura

1980-01-01

347

Direct Observations of Sigma Phase Growth and Dissolution in 2205 Duplex Stainless Steel.  

National Technical Information Service (NTIS)

The formation and growth of sigma (sigma) phase in a 2205 duplex stainless steel is monitored during an 850 degrees C isothermal heat treatment using an in situ synchrotron x-ray diffraction technique. At this temperature, (sigma) phase is first observed ...

T. A. Palmer J. W. Elmer S. S. Babu E. D. Specht

2005-01-01

348

Direct and Remote Sensing Observations of the Effects of Ships on Clouds  

Microsoft Academic Search

Under certain conditions ships can affect the structure of shallow layer clouds. Simultaneous observations of two ship track signatures in stratus clouds from a satellite and in situ from an aircraft show that in the ship tracks the droplet sizes were reduced and total concentrations of both droplets and particles were substantially increased from those in adjacent clouds. In situ

LAWRENCE F. UDKE; JAMES A. COAKLEY; MICHAEL D. KING

1989-01-01

349

Direct observation of antiphase discommensurations in TiSe2 by transmission electron microscopy  

Microsoft Academic Search

Antiphase boundaries associated with the charge density wave superlattice in 1T-TiSe2 have been observed by satellite dark-field transmission electron microscopy. By analogy with 2H-TaSe2, the antiphase boundaries in TiSe2 are interpreted as antiphase discommensurations associated with a commensurability of order two.

K. k. Fung

1985-01-01

350

DIRECT OBSERVATION OF A SHARP TRANSITION TO COHERENCE IN DENSE CORES  

SciTech Connect

We present NH{sub 3} observations of the B5 region in Perseus obtained with the Green Bank Telescope. The map covers a region large enough ({approx}11'x14') that it contains the entire dense core observed in previous dust continuum surveys. The dense gas traced by NH{sub 3}(1,1) covers a much larger area than the dust continuum features found in bolometer observations. The velocity dispersion in the central region of the core is small, presenting subsonic non-thermal motions which are independent of scale. However, it is because of the coverage and high sensitivity of the observations that we present the detection, for the first time, of the transition between the coherent core and the dense but more turbulent gas surrounding it. This transition is sharp, increasing the velocity dispersion by a factor of 2 in less than 0.04 pc (the 31'' beam size at the distance of Perseus, {approx}250 pc). The change in velocity dispersion at the transition is {approx}3 km s{sup -1} pc{sup -1}. The existence of the transition provides a natural definition of dense core: the region with nearly constant subsonic non-thermal velocity dispersion. From the analysis presented here, we can neither confirm nor rule out a corresponding sharp density transition.

Pineda, Jaime E.; Goodman, Alyssa A.; Foster, Jonathan B.; Myers, Philip C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Arce, Hector G. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Caselli, Paola [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Rosolowsky, Erik W. [University of British Columbia Okanagan, 3333 University Way, Kelowna, BC V1V 1V7 (Canada)], E-mail: jpineda@cfa.harvard.edu

2010-03-20

351

Direct observation and control of magnetic monopole defects in an artificial spin-ice material  

Microsoft Academic Search

Magnetic monopoles have stimulated a great amount of theoretical and experimental interest since their prediction by Dirac in 1931. To date, their presence has evaded detection in high energy experiments despite intensive efforts. Recently, entities that mimic magnetic monopoles have been observed in bulk and planar frustrated materials known as spin-ice materials, and artificial spin-ice materials, respectively. In this paper

S. Ladak; D. E. Read; W. R. Branford; L. F. Cohen

2011-01-01

352

An Improved Microscope Stage for Direct Observation of Freezing and Freeze Drying  

Microsoft Academic Search

A microscope stage for observation of freezing and freeze drying is described. The stage uses thermoelectric (Peltier) heaters configured in two stages, with circulating fluid as a heat sink on the high temperature side. Lowest attainable sample temperature is about -47°C. Principal advantages of this system are closed-loop control of stage temperature, rapid response to changes in temperature set point,

Steven L. Nail; Lih-Min Her; Christopher P. B. Proffitt; Lisa L. Nail

1994-01-01

353

Direct observation of hydrogen atom dynamics and interactions by ultrahigh resolution neutron protein crystallography  

PubMed Central

The 1.1 ?, ultrahigh resolution neutron structure of hydrogen/deuterium (H/D) exchanged crambin is reported. Two hundred ninety-nine out of 315, or 94.9%, of the hydrogen atom positions in the protein have been experimentally derived and resolved through nuclear density maps. A number of unconventional interactions are clearly defined, including a potential O?H…? interaction between a water molecule and the aromatic ring of residue Y44, as well as a number of potential C?H…O hydrogen bonds. Hydrogen bonding networks that are ambiguous in the 0.85 ? ultrahigh resolution X-ray structure can be resolved by accurate orientation of water molecules. Furthermore, the high resolution of the reported structure has allowed for the anisotropic description of 36 deuterium atoms in the protein. The visibility of hydrogen and deuterium atoms in the nuclear density maps is discussed in relation to the resolution of the neutron data.

Chen, Julian C.-H.; Hanson, B. Leif; Fisher, S. Zoe; Langan, Paul; Kovalevsky, Andrey Y.

2012-01-01

354

Observation of cluster size growth in CO-directed synthesis of Au25(SR)18 nanoclusters.  

PubMed

The design of an efficient synthesis for large-scale production of atomically precise nanoclusters (NCs) is pivotal in realizing the size-dependent properties of the NCs. A simple and versatile method for producing atomically precise thiolated gold NCs (Au(25)(SR)(18) NCs) in large quantities (~200 mg) is demonstrated in this study. It uses a gaseous reducing agent, carbon monoxide (CO), to support a slow and size-controlled growth of Au(25)(SR)(18) NCs. Absorption measurements of the reaction solution, which underwent distinct color changes (colorless ? yellow ? orange ? brown ? red-brown), allowed the formation of thiolated Au(25) NCs to be reconstructed from several key intermediates. The unique reaction environment provided by gaseous CO presents a new synthetic route to fabricate atomically precise metal NCs in quantities large enough for application explorations. PMID:22913667

Yu, Yong; Luo, Zhentao; Yu, Yue; Lee, Jim Yang; Xie, Jianping

2012-09-25

355

Analytic Bounds on Causal Risk Differences in Directed Acyclic Graphs Involving Three Observed Binary Variables.  

PubMed

We apply a linear programming approach which uses the causal risk difference (RD(C)) as the objective function and provides minimum and maximum values that RD(C) can achieve under any set of linear constraints on the potential response type distribution. We consider two scenarios involving binary exposure X, covariate Z and outcome Y. In the first, Z is not affected by X, and is a potential confounder of the causal effect of X on Y. In the second, Z is affected by X and intermediate in the causal pathway between X and Y. For each scenario we consider various linear constraints corresponding to the presence or absence of arcs in the associated directed acyclic graph (DAG), monotonicity assumptions, and presence or absence of additive-scale interactions. We also estimate Z-stratum-specific bounds when Z is a potential effect measure modifier and bounds for both controlled and natural direct effects when Z is affected by X. In the absence of any additional constraints deriving from background knowledge, the well-known bounds on RDc are duplicated: -Pr(Y not equalX)

Kaufman, Sol; Kaufman, Jay S; Maclehose, Richard F

2009-10-01

356

Direct observation of dynamic charge stripes in La2 xSrxNiO4  

SciTech Connect

The insulator-to-metal transition continues to be a challenging subject, especially when electronic correlations are strong. In layered compounds, such as La2 xSrxNiO4 and La2 xBaxCuO4, the doped charge carriers can segregate into periodically spaced charge stripes separating narrow domains of antiferromagnetic order. Although there have been theoretical proposals of dynamically fluctuating stripes, direct spectroscopic evidence of charge-stripe fluctuations has been lacking. Here we report the detection of critical lattice fluctuations, driven by charge-stripe correlations, in La2 xSrxNiO4 using inelastic neutron scattering. This scattering is detected at large momentum transfers where the magnetic form factor suppresses the spin fluctuation signal. The lattice fluctuations associated with the dynamic charge stripes are narrow in q and broad in energy. They are strongest near the charge-stripe melting temperature. Our results open the way towards the quantitative theory of dynamic stripes and for directly detecting dynamical charge stripes in other strongly correlated systems, including high-temperature superconductors such as La2 xSrxCuO4.

Anissimova, S. [University of Colorado, Boulder] [University of Colorado, Boulder; Parshall, D [University of Colorado, Boulder] [University of Colorado, Boulder; Gu, Genda [Brookhaven National Laboratory (BNL)] [Brookhaven National Laboratory (BNL); Marty, K. [Oak Ridge National Laboratory (ORNL)] [Oak Ridge National Laboratory (ORNL); Lumsden, Mark D [ORNL] [ORNL; Chi, Songxue [ORNL] [ORNL; Fernandez-Baca, Jaime A [ORNL] [ORNL; Abernathy, D. [Oak Ridge National Laboratory (ORNL)] [Oak Ridge National Laboratory (ORNL); Lamago, D. [Laboratoire Leon Brillouin, France] [Laboratoire Leon Brillouin, France; Tranquada, John M. [Brookhaven National Laboratory (BNL)] [Brookhaven National Laboratory (BNL); Reznik, Dmitry [University of Colorado, Boulder] [University of Colorado, Boulder

2014-01-01

357

Direct observation of oil consumption mechanisms in a production spark ignition engine using fluorescence techniques  

NASA Astrophysics Data System (ADS)

The oil consumption characteristics of a four cylinder, normally aspirated spark-ignition engine were investigated for different piston ring end-gap configurations. A radiotracer was used to perform direct measurement of the oil consumption while Laser-induced Fluorescence (LIF) was used to perform the oil film thickness measurements for consumption predictions using the 'Puddle Theory of Oil Consumption,' which relates oil consumption to second land film thickness and reverse flow through top ring gap. The consumption data was evaluated to determine the impact of top ring end-gap azimuthal location on oil consumption. The film thickness data was used to evaluate the extent to which the oil Puddle Theory predicts variations seen in the actual oil consumption. A tritium radiotracer oil consumption measurement system with an accuracy of 94.6 percent was designed and constructed. This was used to perform direct measurements of the test engine oil consumption in two different test matrices. The first evaluated a piston ring configuration with the rings free to rotate. The second evaluated configurations with the top ring and second piston rings pinned to fix the azimuthal location of the end-gap; the azimuth of the top ring was varied. In the second test matrix, the oil film thickness on the piston's second land was measured, and predictions were made on the basis of that measurement.

Lusted, Roderick M.

1994-05-01

358

Direct observations of thermally induced structural changes in amorphous silicon carbide  

SciTech Connect

Thermally induced structural relaxation in amorphous silicon carbide (SiC) has been examined by means of in situ transmission electron microscopy (TEM). The amorphous SiC was prepared by high-energy ion-beam-irradiation into a single crystalline 4H-SiC substrate. Cross-sectional TEM observations and electron energy-loss spectroscopy measurements revealed that thermal annealing induces a remarkable volume reduction, so-called densification, of amorphous SiC. From radial distribution function analyses using electron diffraction, notable changes associated with structural relaxation were observed in chemical short-range order. On the basis of the alteration of chemical short-range order, we discuss the origin of thermally induced densification in amorphous SiC.

Ishimaru, Manabu; Hirata, Akihiko; Naito, Muneyuki; Bae, In-Tae; Zhang, Yanwen; Weber, William J.

2008-08-01

359

Direct and remote sensing observations of the effects of ships on clouds  

NASA Technical Reports Server (NTRS)

Under certain conditions ships can affect the structure of shallow layer clouds. Simultaneous observations of two ship track signatures in stratus clouds from a satellite and in situ from an aircraft show that in the ship tracks the droplet sizes were reduced and total concentrations of both droplets and particles were substantially increased from those in adjacent clouds. In situ measurements of the upwelling radiance within the ship tracks was significantly enhanced at visible wavelengths, whereas radiance at 2.2 micrometers was significantly reduced. Cloud reflectivity along the tracks was enhanced at 0.63 and 3.7 micrometers. These observations support the contention that ship track signatures in clouds are produced primarily by particles emitted from ships.

Radke, Lawrence F.; Coakley, James A., Jr.; King, Michael D.

1989-01-01

360

Direct constraint on the distance of y2 Velorum from AMBER\\/VLTI observations  

Microsoft Academic Search

In this work, we present the first AMBER observations, of the Wolf-Rayet and\\u000aO (WR+O) star binary system y2 Velorum. The AMBER instrument was used with the\\u000atelescopes UT2, UT3, and UT4 on baselines ranging from 46m to 85m. It delivered\\u000aspectrally dispersed visibilities, as well as differential and closure phases,\\u000awith a resolution R = 1500 in the spectral

F. Millour; R. G. Petrov; O. Chesneau; D. Bonneau; L. Dessart; C. Bechet; I. Tallon-Bosc; M. Tallon; E. Thiébaut; F. Vakili; F. Malbet; D. Mourard; G. Zins; A. Roussel; S. Robbe-Dubois; P. Puget; K. Perraut; F. Lisi; E. Le Coarer; S. Lagarde; P. Kern; L. Glück; G. Duvert; A. Chelli; Y. Bresson; U. Beckmann; P. Antonelli; G. Weigelt; N. Ventura; M. Vannier; J.-C. Valtier; L. Testi; E. Tatulli; D. Tasso; P. Stefanini; P. Stee; W. Solscheid; D. Schertl; P. Salinari; M. Sacchettini; A. Richichi; F. Reynaud; S. Rebattu; Y. Rabbia; T. Preibisch; C. Perrier; F. Pacini; K. Ohnaka; E. Nussbaum; D. Mouillet; J.-L. Monin; P. Mège; P. Mathias; G. Martinot-Lagarde; G. Mars; A. Marconi; Y. Magnard; B. Lopez; D. Le Contel; J.-M. Le Contel; S. Kraus; D. Kamm; K.-H. Hofmann; O. Hernandez Utrera; M. Heininger; M. Heiden; C. Gil; E. Giani; A. Glentzlin; S. Gennari; A. Gallardo; D. Fraix-Burnet; R. Foy; E. Fossat; T. Forveille; D. Ferruzzi; P. Feautrier; M. Dugué; T. Driebe; A. Domiciano De Souza; A. Delboulbé; C. Connot; J. Colin; J.-M. Clausse; F. Cassaing; S. Busoni; S. Bonhomme; T. Blöcker; J. Behrend; C. Baffa; E. Aristidi; B. Arezki; K. Agabi; B. Acke; M. Accardo; M. Kiekebusch; F. Rantakyrö; Markus Schoeller

2006-01-01

361

Direct Observation of Microscopic Reversibility in Single-molecule Protein Folding  

Microsoft Academic Search

Both folded and unfolded conformations should be observed for a protein at its melting temperature (Tm), where ?G between these states is zero. In an all-atom molecular dynamics simulation of chymotrypsin inhibitor 2 (CI2) at its experimental Tm, the protein rapidly loses its low-temperature native structure; it then unfolds before refolding to a stable, native-like conformation. The initial unfolding follows

Ryan Day; Valerie Daggett

2007-01-01

362

Direct observation of spin-like reaction fronts in planar energetic multilayer foils.  

SciTech Connect

Propagating reactions in initially planar cobalt/aluminum exothermic multilayer foils have been investigated using high-speed digital photography. Real-time observations of reactions indicate that unsteady (spinlike) reaction propagation leads to the formation of highly periodic surface morphologies with length scales ranging from 1 {micro}m to 1 mm. The characteristics of propagating spinlike reactions and corresponding reacted foil morphologies depend on the bilayer thickness of multilayer foils.

Adams, David Price; Hodges, V. Carter; Jones, Eric D., Jr.; McDonald, Joel Patrick

2008-10-01

363

Coupled plasmon modes in an ordered hexagonal monolayer of metal nanoparticles: a direct observation.  

PubMed

We report on the experimental observation of STM-induced photon emission in ultrahigh vacuum on a network of 4-nm silver spheres. The spheres are covered by a dielectric, electrically insulating, organic layer and deposited on Au(111). The bias-dependent spatial distribution of the photon emission rates reveals the electric-field distribution of the different coupled plasmon modes in this model. PMID:10991068

Silly, F; Gusev, A O; Taleb, A; Charra, F; Pileni, M P

2000-06-19

364

Coupled Plasmon Modes in an Ordered Hexagonal Monolayer of Metal Nanoparticles: A Direct Observation  

Microsoft Academic Search

We report on the experimental observation of STM-induced photon emission in ultrahigh vacuum on a network of 4-nm silver spheres. The spheres are covered by a dielectric, electrically insulating, organic layer and deposited on Au(111). The bias-dependent spatial distribution of the photon emission rates reveals the electric-field distribution of the different coupled plasmon modes in this model.

Fabien Silly; Alexander O. Gusev; Abdelhafed Taleb; Fabrice Charra; Marie-Paule Pileni

2000-01-01

365

TRMM Observed First Direct Evidence of Smoke from Forest Fires Inhibiting Rainfall  

Microsoft Academic Search

Although it has been known that smoke from biomass burning suppresses warm rain processes, it was not known to what extent this occurs. The satellite observations of the Tropical-Rainfall-Measuring-Mission (TRMM), presented here, show that warm rain processes in convective tropical clouds infected by heavy smoke from forest fires are practically shut off. The tops of the smoke-infected clouds must exceed

Daniel Rosenfeld

1999-01-01

366

Direct observation of protein folding in nanoenvironments using a molecular ruler  

Microsoft Academic Search

We observe folding of horse heart cytochrome c in various environments including nano-compartments (micelles and reverse micelles). Using picosecond-resolved Förster resonance energy transfer (FRET) dynamics of an extrinsic covalently attached probe dansyl (donor) at the surface of the protein to a heme group (acceptor) embedded inside the protein, we measured angstrom-resolved donor–acceptor distances in the environments. The overall structural perturbations

Rupa Sarkar; Ajay Kumar Shaw; S. Shankara Narayanan; Fernando Dias; Andy Monkman; Samir Kumar Pal

2006-01-01

367

Acidification of the North Pacific Ocean: Direct Observations of pH in 1991 and 2006  

Microsoft Academic Search

Spectrophotometric procedures were first successfully used to obtain seawater pH profiles on a 1991 cruise within the CLIVAR\\/CO2 Repeat Hydrography Program. During a 2006 reoccupation of the P16N transect along 152 ^{0}W, closely similar methods were used to obtain a fifteen-year spectrophotometrically-based record of ocean pH change. Spectrophotometric procedures are particularly robust as a means of observing changes in seawater

R. H. Byrne; X. Liu; S. Mecking; R. A. Feely

2006-01-01

368

Direct Observation of the Three-State Folding of a Single Protein Molecule  

Microsoft Academic Search

We used force-measuring optical tweezers to induce complete mechanical unfolding and refolding of individual Escherichia coli ribonuclease H (RNase H) molecules. The protein unfolds in a two-state manner and refolds through an intermediate that correlates with the transient molten globule-like intermediate observed in bulk studies. This intermediate displays unusual mechanical compliance and unfolds at substantially lower forces than the native

Ciro Cecconi; Elizabeth A. Shank; Carlos Bustamante; Susan Marqusee

2005-01-01

369

First direct observation of time-reversal non-invariance in the neutral-kaon system  

Microsoft Academic Search

We report on the first observation of time-reversal symmetry violation through a comparison of the probabilities of K0 transforming into K0 and K0 into K0 as a function of the neutral-kaon eigentime t. The comparison is based on the analysis of the neutral-kaon semileptonic decays recorded in the CPLEAR experiment. There, the strangeness of the neutral kaon at time t=0

A. Angelopoulos; E. Aslanides; G. Backenstoss; P. Bargassa; O. Behnke; A. Benelli; V. Bertin; F. Blanc; P. Bloch; P. Carlson; M. Carroll; E. Cawley; S. Charalambous; M. B. Chertok; M. Danielsson; M. Danielsson; J. Derre; A. Ealet; C. Eleftheriadis; L. Faravel; W. Fetscher; M. Fidecaro; A. Filip?i?; D. Francis; J. Fry; E. Gabathuler; R. Gamet; H.-J. Gerber; A. Go; A. Haselden; P. J. Hayman; F. Henry-Couannier; R. W. Hollander; P.-R. Kettle; P. Kokkas; R. Kreuger; R. Le Gac; F. Leimgruber; I. Mandi?; N. Manthos; G. Marel; M. Mikuž; J. Miller; F. Montanet; A. Muller; T. Nakada; B. Pagels; I. Papadopoulos; P. Pavlopoulos; A. Policarpo; G. Polivka; R. Rickenbach; B. L. Roberts; T. Ruf; C. Santoni; M. Schäfer; L. A. Schaller; T. Schietinger; A. Schopper; L. Tauscher; C. Thibault; F. Touchard; C. Touramanis; C. W. E. Van Eijk; S. Vlachos; P. Weber; O. Wigger; M. Wolter; D. Zavrtanik; D. Zavrtanik; D. Zimmerman

1998-01-01

370

Value-directed human behavior analysis from video using partially observable Markov decision processes.  

PubMed

This paper presents a method for learning decision theoretic models of human behaviors from video data. Our system learns relationships between the movements of a person, the context in which they are acting, and a utility function. This learning makes explicit that the meaning of a behavior to an observer is contained in its relationship to actions and outcomes. An agent wishing to capitalize on these relationships must learn to distinguish the behaviors according to how they help the agent to maximize utility. The model we use is a partially observable Markov decision process, or POMDP. The video observations are integrated into the POMDP using a dynamic Bayesian network that creates spatial and temporal abstractions amenable to decision making at the high level. The parameters of the model are learned from training data using an a posteriori constrained optimization technique based on the expectation-maximization algorithm. The system automatically discovers classes of behaviors and determines which are important for choosing actions that optimize over the utility of possible outcomes. This type of learning obviates the need for labeled data from expert knowledge about which behaviors are significant and removes bias about what behaviors may be useful to recognize in a particular situation. We show results in three interactions: a single player imitation game, a gestural robotic control problem, and a card game played by two people. PMID:17496372

Hoey, Jesse; Little, James J

2007-07-01

371

Nature of the clinical difficulties of first-year family medicine residents under direct observation.  

PubMed Central

OBJECTIVE: To determine and classify the difficulties of first-year family medicine residents observed during clinical interviews. DESIGN: Retrospective, descriptive study. SETTING: Family practice unit at a teaching hospital. PARTICIPANTS: Forty-seven of the 56 first-year family medicine residents during their 2-month compulsory rotation in ambulatory family medicine, between July 1983 and December 1988, and 4 physicians who supervised the residents. MAIN OUTCOME MEASURE: The residents' difficulties noted on the observation forms. MAIN RESULTS: A total of 1500 difficulties were observed during 194 interviews, an average of 7.7 (standard deviation 5.2) per interview. There were 167 different difficulties, which were classified into seven categories (introduction, initial contract, body of the interview, techniques and organization, interpersonal aspects, final contract and miscellaneous) and 20 subcategories. The 17 most frequently noted difficulties accounted for 40% of the total. CONCLUSIONS: The results constitute a useful starting point for developing a classification of residents' difficulties during clinical interviews. We believe that the list of difficulties is applicable to residents at all levels and in other specialties, especially in ambulatory settings. The list can be used to develop learning materials for supervisors and residents.

Beaumier, A; Bordage, G; Saucier, D; Turgeon, J

1992-01-01

372

Direct observation of a 'devil's staircase' in wave-particle interaction  

SciTech Connect

We report the experimental observation of a 'devil's staircase' in a time-dependent system considered as a paradigm for the transition to large-scale chaos in the universality class of Hamiltonian systems. A test electron beam is used to observe its non-self-consistent interaction with externally excited wave(s) in a traveling wave tube (TWT). A trochoidal energy analyzer records the beam energy distribution at the output of the interaction line. An arbitrary waveform generator is used to launch a prescribed spectrum of waves along the slow wave structure (a 4 m long helix) of the TWT. The resonant velocity domain associated to a single wave is observed, as well as the transition to large-scale chaos when the resonant domains of two waves and their secondary resonances overlap. This transition exhibits a 'devil's staircase' behavior for increasing excitation amplitude, due to the nonlinear forcing by the second wave on the pendulum-like motion of a charged particle in one electrostatic wave.

Doveil, Fabrice; Macor, Alessandro; Elskens, Yves [Physique des interactions ioniques et moleculaires, Unite 6633 CNRS-Universite de Provence, Equipe turbulence plasma, case 321, Centre de Saint-Jerome, F-13397 Marseille cedex 20 (France)

2006-09-15

373

Direct observation of a "devil's staircase" in wave-particle interaction.  

PubMed

We report the experimental observation of a "devil's staircase" in a time-dependent system considered as a paradigm for the transition to large-scale chaos in the universality class of Hamiltonian systems. A test electron beam is used to observe its non-self-consistent interaction with externally excited wave(s) in a traveling wave tube (TWT). A trochoidal energy analyzer records the beam energy distribution at the output of the interaction line. An arbitrary waveform generator is used to launch a prescribed spectrum of waves along the slow wave structure (a 4 m long helix) of the TWT. The resonant velocity domain associated to a single wave is observed, as well as the transition to large-scale chaos when the resonant domains of two waves and their secondary resonances overlap. This transition exhibits a "devil's staircase" behavior for increasing excitation amplitude, due to the nonlinear forcing by the second wave on the pendulum-like motion of a charged particle in one electrostatic wave. PMID:17014208

Doveil, Fabrice; Macor, Alessandro; Elskens, Yves

2006-09-01

374

Direct observation of multiferroic vortex domains in YMnO3.  

PubMed

Topological vortices with swirling ferroelectric, magnetic and structural anti-phase relationship in hexagonal RMnO3 (R = Ho to Lu, Y, and Sc) have attracted much attention because of their intriguing behaviors. Herein, we report the structure of multiferroic vortex domains in YMnO3 at atomic scale using state-of-the-art aberration-corrected scanning transmission electron microscopy (STEM). Two types of displacements were identified among six domain walls (DWs); six translation-ferroelectric domains denoted by ?+, ?-, ?+, ?-, ?+ and ?-, respectively, were recognized, demonstrating the interlocking nature of the anti-vortex domain. We found that the anti-vortex core is about four unit cells wide. In addition, we reconstructed the vortex model with three swirling pairs of DWs along the [001] direction. These results are very critical for the understanding of topological behaviors and unusual properties of the multiferroic vortex. PMID:24061552

Zhang, Qinghua; Tan, Guotai; Gu, Lin; Yao, Yuan; Jin, Changqing; Wang, Yanguo; Duan, Xiaofeng; Yu, Richeng

2013-01-01

375

High-temperature corrosion observed in austenitic coils and tubes in a direct reduction process  

NASA Astrophysics Data System (ADS)

The subject of this study is related to the performance of austenitic steel coils and tubes, in a range of temperatures between 425 and 870°C for the transport of reducing gas, in an installation involving the direct reduction of iron-ore by reforming natural gas. Evidence is presented that metal dusting is not the only unique high-temperature corrosion mechanism that caused catastrophic failures of austenitic 304 (UNS S304 00) coils and HK-40 (UNS J94204) tubes. Sensitization as well as stress corrosion cracking occurred in 304 stainless steel coils and metal dusting took place in HK-40 tubes, a high resistance alloy. The role of continuous injection of H2S into the process is suggested to avoid the high resistance metal dusting corrosion mechanism found in this kind of installation.

Campillo, B.; Gonzales, C.; Hernandez-Duque, G.; Juarez-Islas, J. A.

2000-02-01

376

Direct observation of the trapping of deuterium ions at a grain boundary in tungsten  

SciTech Connect

The imaging atom-probe/field ion microscope has been used to study the trapping of low-energy deuterium ions in tungsten. The experimental results indicate that implanted deuterium does not remain trapped in a tungsten lattice at room temperature for a period of several days unless a defect is present. Time-gated imaging atom-probe images show the first direct correlation between the trapped deuterium and the presence of a grain boundary on an atomic scale. Comparing these results to secondary-ion mass spectrometer and nuclear reaction analyses of simultaneously exposed, flat tungsten, and silicon samples indicates that the imaging atom-probe is sensitive to low levels of hydrogen concentration at lattice defects that are invisible to these other two techniques. The implications of the experiment relating to tokamak plasma-wall and hydrogen embrittlement studies are discussed.

Kellogg, G.L.; Panitz, J.K.G.

1980-10-01

377

Direct observation of ultrafast long-range charge separation at polymer-fullerene heterojunctions.  

PubMed

In polymeric semiconductors, charge carriers are polarons, which means that the excess charge deforms the molecular structure of the polymer chain that hosts it. This results in distinctive signatures in the vibrational modes of the polymer. Here, we probe polaron photogeneration dynamics at polymer:fullerene heterojunctions by monitoring its time-resolved resonance-Raman spectrum following ultrafast photoexcitation. We conclude that polarons emerge within 300?fs. Surprisingly, further structural evolution on ?50-ps timescales is modest, indicating that the polymer conformation hosting nascent polarons is not significantly different from that near equilibrium. We interpret this as suggestive that charges are free from their mutual Coulomb potential because we would expect rich vibrational dynamics associated with charge-pair relaxation. We address current debates on the photocarrier generation mechanism at molecular heterojunctions, and our work is, to our knowledge, the first direct probe of molecular conformation dynamics during this fundamentally important process in these materials. PMID:24980429

Provencher, Françoise; Bérubé, Nicolas; Parker, Anthony W; Greetham, Gregory M; Towrie, Michael; Hellmann, Christoph; Côté, Michel; Stingelin, Natalie; Silva, Carlos; Hayes, Sophia C

2014-01-01

378

Paul trapping of radioactive 6He+ ions and direct observation of their beta decay.  

PubMed

We demonstrate that abundant quantities of short-lived beta unstable ions can be trapped in a novel transparent Paul trap and that their decay products can directly be detected in coincidence. Low energy 6He+ (807 ms half-life) ions were extracted from the SPIRAL source at GANIL, then decelerated, cooled, and bunched by means of the buffer gas cooling technique. More than 10(8) ions have been stored over a measuring period of six days, and about 10(5) decay coincidences between the beta particles and the 6Li++ recoiling ions have been recorded. The technique can be extended to other short-lived species, opening new possibilities for trap assisted decay experiments. PMID:19113407

Fléchard, X; Liénard, E; Méry, A; Rodríguez, D; Ban, G; Durand, D; Duval, F; Herbane, M; Labalme, M; Mauger, F; Naviliat-Cuncic, O; Thomas, J C; Velten, Ph

2008-11-21

379

Direct atomic-scale observation of layer-by-layer oxide growth during magnesium oxidation  

NASA Astrophysics Data System (ADS)

The atomic-scale oxide growth dynamics are directly revealed by in situ high resolution transmission electron microscopy during the oxidation of Mg surface. The oxidation process is characterized by the layer-by-layer growth of magnesium oxide (MgO) nanocrystal via the adatom process. Consistently, the nucleated MgO crystals exhibit faceted surface morphology as enclosed by {200} lattice planes. It is believed that the relatively lower surface energies of {200} lattice planes should play important roles, governing the growth mechanism. These results facilitate the understanding of the nanoscale oxide growth mechanism that will have an important impact on the development of magnesium or magnesium alloys with improved resistance to oxidation.

Zheng, He; Wu, Shujing; Sheng, Huaping; Liu, Chun; Liu, Yu; Cao, Fan; Zhou, Zhichao; Zhao, Xingzhong; Zhao, Dongshan; Wang, Jianbo

2014-04-01

380

High-temperature corrosion observed in austenitic coils and tubes in a direct reduction process  

SciTech Connect

The subject of this study is related to the performance of austenitic steel coils and tubes, in a range of temperatures between 425 and 870 C for the transport of reducing gas, in an installation involving the direct reduction of iron-ore by reforming natural gas. Evidence is presented that metal dusting is not the only unique high-temperature corrosion mechanism that caused catastrophic failures of austenitic 304 (UNS S30400) coils and HK-40 (UNS J94204) tubes. Sensitization as well as stress corrosion cracking occurred in 304 stainless steel coils and metal dusting took place in HK-40 tubes, a high resistance alloy. The role of continuous injection of H{sub 2}S into the process is suggested to avoid the high resistance metal dusting corrosion mechanism found in this kind of installation.

Campillo, B.; Gonzalez, C.; Hernandez-Duque, G.; Juarez-Islas, J.A.

2000-02-01

381

Direct Observations of Explosive Eruptive Activity at a Submarine Volcano, NW Rota-1, Mariana Arc  

NASA Astrophysics Data System (ADS)

In April 2006, a series of extraordinary observations of a deep-sea volcanic eruption were made at NW Rota-1, located at 14^{circ}36'N in the Mariana arc, western Pacific. This is a conical, basaltic-andesite submarine volcano with a summit depth of 517 m. Explosive eruptive activity at NW Rota-1 was discovered in 2004 and was witnessed again in 2005, but the activity in 2006 was especially vigorous and well documented. During six dives with the remotely operated vehicle Jason II over a period of 7 days, video observations made at close range documented a diverse and increasingly energetic range of volcanic activity that culminated in explosive bursts with flashes of glowing red lava propelled by violently expanding gases. Other notable activity included discreet degassing events, extrusion of sluggish lava flows, explosions that formed dilute density currents and/or expelled rocks and ash tens of meters from the vent, and rapid pressure oscillations apparently caused by the repeated formation and condensation of steam. During the last dive when the highest extrusion rates were observed, quasi-periodic bursts from the vent, each lasting 1-10 minutes, were separated by pauses lasting 10 seconds to a few minutes. Each burst started as a plug of crusted-over lava rose in the vent and was blown apart by expanding gases, producing large lava bombs with distinctly flat, disc-like shapes. A remarkable aspect of these observations was how close Jason II could be to the vent during the eruptions. This was because the pressure of the overlying seawater dampened the energy of the explosions and slowed the velocity of volcanic ejecta. Also, lava degassing could be visualized with great clarity underwater as either clear bubbles (CO2) or opaque yellow clouds (dominated by SO2 and H2S). A portable hydrophone with a 30-hour recording capacity was deployed twice by Jason II at the summit of NW Rota-1 during the 2006 dive series. The hydrophone data extends the visual observations made at the vent and quantifies the temporal pattern and intensity of the eruptive activity. The expedition to NW Rota-1 in 2006 was supported by the NOAA Ocean Exploration Program.

Chadwick, W. W.; Embley, R. W.; de Ronde, C. E.; Deardorff, N.; Matsumoto, H.; Cashman, K. V.; Dziak, R. P.; Merle, S. G.

2006-12-01

382

Direct observation of electrogenic NH4+ transport in ammonium transport (Amt) proteins.  

PubMed

Ammonium transport (Amt) proteins form a ubiquitous family of integral membrane proteins that specifically shuttle ammonium across membranes. In prokaryotes, archaea, and plants, Amts are used as environmental NH4 (+) scavengers for uptake and assimilation of nitrogen. In the eukaryotic homologs, the Rhesus proteins, NH4 (+)/NH3 transport is used instead in acid-base and pH homeostasis in kidney or NH4 (+)/NH3 (and eventually CO2) detoxification in erythrocytes. Crystal structures and variant proteins are available, but the inherent challenges associated with the unambiguous identification of substrate and monitoring of transport events severely inhibit further progress in the field. Here we report a reliable in vitro assay that allows us to quantify the electrogenic capacity of Amt proteins. Using solid-supported membrane (SSM)-based electrophysiology, we have investigated the three Amt orthologs from the euryarchaeon Archaeoglobus fulgidus. Af-Amt1 and Af-Amt3 are electrogenic and transport the ammonium and methylammonium cation with high specificity. Transport is pH-dependent, with a steep decline at pH values of ?5.0. Despite significant sequence homologies, functional differences between the three proteins became apparent. SSM electrophysiology provides a long-sought-after functional assay for the ubiquitous ammonium transporters. PMID:24958855

Wacker, Tobias; Garcia-Celma, Juan J; Lewe, Philipp; Andrade, Susana L A

2014-07-01

383

Direct Observation of Electron Capture and Reemission by the Divacancy via Charge Transient Positron Spectroscopy  

NASA Astrophysics Data System (ADS)

Electron capture during forward bias and reemission at zero bias by divacancies in the depletion region of a silicon diode structure at room temperature have been studied for the first time using monoenergetic positrons. The positron response increases essentially linearly with electron current, as a result of increased positron trapping by negatively charged divacancies. The measurements indicate that ?1% of the divacancies become negatively charged in the steady state at a forward bias of 1 V. Changes in the mean positron response when applying a square wave bias to the sample (1 V forward bias and 0 V, duty cycle 1?4, times at 0 V in the range 0.1-100?s), were consistent with a rapid conversion of doubly to singly charged divacancies (in ˜101ns), followed by slower defilling of the singly charged divacancies with a time constant of ˜101?s. These ac measurements allow determination of the relative populations of singly and doubly charged divacancies. The results provide confirmation of consistency between the positron’s response to the silicon divacancy and previously extracted capture and emission kinetics determined through charge transient measurements and assigned to the same defect. The possibility of combining these two, orthogonal techniques suggest a promising new and powerful approach to defect spectroscopy in which the structure and electrical properties of a defect may be determined in a single measurement.

Edwardson, C. J.; Coleman, P. G.; Paez, D. J.; Doylend, J. K.; Knights, A. P.

2013-03-01

384

Direct and instantaneous observation of intravenously injected substances using intravital confocal micro-videography.  

PubMed

We describe the development and application of intravital confocal micro-videography to visualize entrance, distribution, and clearance of drugs within various tissues and organs. We use a Nikon A1R confocal laser scanning microscope system attached to an upright ECLIPSE FN1. The Nikon A1R allows simultaneous four channel acquisition and speed of 30 frames per second while maintaining high resolution of 512 × 512 scanned points. The key techniques of our intravital imaging are (1) to present a flat and perpendicular surface to the objective lens, and (2) to expose the subject with little or no bleeding to facilitate optical access to multiple tissues and organs, and (3) to isolate the subject from the body movement without compressing the blood vessels, and (4) to insert a tail vein catheter for timed injection without moving the subject. Ear lobe dermis tissue was accessible without surgery. Liver, kidney, and subcutaneous tumor were accessed following exteriorization through skin incision. In order to image initial extravasations of compounds into tissue following intravenous injection, movie acquisition was initialized prior to drug administration. Our technique can serve as a powerful tool for investigating biological mechanisms and functions of intravenously injected drugs, with both spatial and temporal resolution. PMID:21258542

Matsumoto, Yu; Nomoto, Takahiro; Cabral, Horacio; Matsumoto, Yoko; Watanabe, Sumiyo; Christie, R James; Miyata, Kanjiro; Oba, Makoto; Ogura, Tadayoshi; Yamasaki, Yuichi; Nishiyama, Nobuhiro; Yamasoba, Tatsuya; Kataoka, Kazunori

2010-01-01

385

Direct observation of stepped proteolipid ring rotation in E. coli FoF1-ATP synthase  

PubMed Central

Although single-molecule experiments have provided mechanistic insight for several molecular motors, these approaches have proved difficult for membrane bound molecular motors like the FoF1-ATP synthase, in which proton transport across a membrane is used to synthesize ATP. Resolution of smaller steps in Fo has been particularly hampered by signal-to-noise and time resolution. Here, we show the presence of a transient dwell between Fo subunits a and c by improving the time resolution to 10 ?s at unprecedented S/N, and by using Escherichia coli FoF1 embedded in lipid bilayer nanodiscs. The transient dwell interaction requires 163 ?s to form and 175 ?s to dissociate, is independent of proton transport residues aR210 and cD61, and behaves as a leash that allows rotary motion of the c-ring to a limit of ?36° while engaged. This leash behaviour satisfies a requirement of a Brownian ratchet mechanism for the Fo motor where c-ring rotational diffusion is limited to 36°.

Ishmukhametov, Robert; Hornung, Tassilo; Spetzler, David; Frasch, Wayne D

2010-01-01

386

Direct Observation of Intermixing at Ge /Si(001) Interfaces by High-Resolution Rutherford Backscattering Spectroscopy  

NASA Astrophysics Data System (ADS)

The initial stage of Ge/Si(001) epitaxial growth is studied with high-resolution Rutherford backscattering spectroscopy. In contrast to the generally accepted picture, intermixing of Ge and Si begins before the first layer is completed at the growth temperature of 500 °C. If the layer is deposited at room temperature, intermixing takes place during annealing at 300-800 °C. These observations are in reasonable agreement with a recent theoretical study based on generalized gradient approximation density functional calculations [Y. Yoshimoto and M. Tsukada, Surf. Sci. 423, 32 (1999)].

Nakajima, Kaoru; Konishi, Atsushi; Kimura, Kenji

1999-08-01

387

Direct observation of two-dimensional self-focusing of spin waves in magnetic films  

NASA Astrophysics Data System (ADS)

An observation of self-focusing of dipolar spin waves in garnet film media is reported. In particular, we show that the quasistationary diffraction of a finite-aperture spin-wave beam in a focusing medium leads to the concentration of the wave power in one focal point rather than along a certain line (channel). The obtained results demonstrate the wide applicability of nonlinear spin-wave media to study nonlinear wave phenomena using an advanced combined microwave-Brillouin-light-scattering technique for a two-dimensional mapping of the spin-wave amplitudes.

Bauer, M.; Mathieu, C.; Demokritov, S. O.; Hillebrands, B.; Kolodin, P. A.; Sure, S.; Dötsch, H.; Grimalsky, V.; Rapoport, Yu.; Slavin, A. N.

1997-10-01

388

Direct Observation of the Coherent Nuclear Response after the Absorption of a Photon  

NASA Astrophysics Data System (ADS)

How molecules convert light energy to perform a specific transformation is a fundamental question in photophysics. Ultrafast spectroscopy reveals the kinetics associated with electronic energy flow, but little is known about how absorbed photon energy drives nuclear motion. Here we used ultrabroadband transient absorption spectroscopy to monitor coherent vibrational energy flow after photoexcitation of the retinal chromophore. In the proton pump bacteriorhodopsin, we observed coherent activation of hydrogen-out-of-plane wagging and backbone torsional modes that were replaced by unreactive coordinates in the solution environment, concomitant with a deactivation of the reactive relaxation pathway.

Liebel, M.; Schnedermann, C.; Bassolino, G.; Taylor, G.; Watts, A.; Kukura, P.

2014-06-01

389

Direct observation of fine-scale energy banding in echo-enabled harmonic generation  

NASA Astrophysics Data System (ADS)

We describe the experimental observation of highly nonlinear energy striations generated by two lasers in a relativistic electron beam in an echo-enabled harmonic generation (EEHG) setup. The rich energy banding structure results from strong dispersion of the sinusoidally modulated beam, and measurements of the banding spectrum enable benchmarking, optimization, and characterization of the concomitant EEHG process. Results are found to be in good agreement with theory, and suggest that the presented technique can facilitate the practical implementation of EEHG to generate intense, fully coherent light in future advanced accelerator-based light sources.

Hemsing, E.; Xiang, D.; Dunning, M.; Weathersby, S.; Hast, C.; Raubenheimer, T.

2014-01-01

390

Direct observation of the coherent nuclear response after the absorption of a photon.  

PubMed

How molecules convert light energy to perform a specific transformation is a fundamental question in photophysics. Ultrafast spectroscopy reveals the kinetics associated with electronic energy flow, but little is known about how absorbed photon energy drives nuclear motion. Here we used ultrabroadband transient absorption spectroscopy to monitor coherent vibrational energy flow after photoexcitation of the retinal chromophore. In the proton pump bacteriorhodopsin, we observed coherent activation of hydrogen-out-of-plane wagging and backbone torsional modes that were replaced by unreactive coordinates in the solution environment, concomitant with a deactivation of the reactive relaxation pathway. PMID:24972232

Liebel, M; Schnedermann, C; Bassolino, G; Taylor, G; Watts, A; Kukura, P

2014-06-13

391

Extreme ultraviolet spectroscopy of G191-B2B - Direct observation of ionization edges  

NASA Technical Reports Server (NTRS)

We present the first spectrum of the hot, DA white dwarf G191-B2B (wd 0501 + 527) between 200 and 330 A. The spectrum, which has about 2 A resolution, was obtained with a sounding rocket-borne, grazing incidence spectrograph. The spectrum shows no evidence of He II, the expected primary opacity source in this wavelength region. Three ionization edges and one absorption feature were observed and are suggestive of O III existing in the photosphere of G191-B2B. Also noted is a broad spectral depression that may result from Fe VI in the photosphere.

Wilkinson, Erik; Green, James C.; Cash, Webster

1992-01-01

392

Direct observation of optically induced transient structures in graphite using ultrafast electron crystallography.  

PubMed

We use ultrafast electron crystallography to study structural changes induced in graphite by a femtosecond laser pulse. At moderate fluences of < or =21 mJ/cm2, lattice vibrations are observed to thermalize on a time scale of approximately 8 ps. At higher fluences approaching the damage threshold, lattice vibration amplitudes saturate. Following a marked initial contraction, graphite is driven nonthermally into a transient state with sp3-like character, forming interlayer bonds. Using ab initio density functional calculations, we trace the governing mechanism back to electronic structure changes following the photoexcitation. PMID:18764578

Raman, Ramani K; Murooka, Yoshie; Ruan, Chong-Yu; Yang, Teng; Berber, Savas; Tománek, David

2008-08-15

393

Direct Observation of Bloch Harmonics and Negative Phase Velocity in Photonic Crystal Waveguides  

NASA Astrophysics Data System (ADS)

The eigenfield distribution and the band structure of a photonic crystal waveguide have been measured with a phase-sensitive near-field scanning optical microscope. Bloch modes, which consist of more than one spatial frequency, are visualized in the waveguide. In the band structure, multiple Brillouin zones due to zone folding are observed, in which positive and negative dispersion is seen. The negative slopes are shown to correspond to a negative phase velocity but a positive group velocity. The lateral mode profile for modes separated by one reciprocal lattice vector is found to be different.

Gersen, H.; Karle, T. J.; Engelen, R. J.; Bogaerts, W.; Korterik, J. P.; van Hulst, N. F.; Krauss, T. F.; Kuipers, L.

2005-03-01

394

Direct observation of the latitudinal extent of a high-speed stream in the solar wind  

NASA Technical Reports Server (NTRS)

The latitudinal boundaries of stationary fast solar wind streams emerging from equatorward extensions of the sun's polar coronal holes are studied. Simultaneous data from the Helios 1 and Imp spacecraft at different heliographic latitudes are compared. The measured latitudinal speed gradient of 30 km/s/deg shows that large angular speed gradients occur at the leading edges of fast streams and also with respect to latitude. The data indicate that longitudinal speed gradients are steeper near 0.3 AU than at 1.0 AU. Generally, regions with large angular speed gradients are observed to separate fast streams from the surrounding slower plasma. This suggests the existence of mechanisms which diminish longitudinal speed gradients as the plasma travels toward 1.0 AU. It also seems that the distribution of solar wind speeds on a near-sun spherical surface has large mesalike high-speed regions. Comparisons of Helios 1 and Imp data with corona observations supports the hypothesis that high-speed solar wind streams emerge from coronal holes.

Schwenn, R.; Montgomery, M. D.; Rosenbauer, H.; Miggenrieder, H.; Muehlhaeuser, K. H.; Bame, S. J.; Feldman, W. C.; Hansen, R. T.

1978-01-01

395

Intramolecular vibrational dynamics in S1 p-fluorotoluene. I. Direct observation of doorway states.  

PubMed

Picosecond time-resolved photoelectron spectroscopy is used to investigate intramolecular vibrational redistribution (IVR) following excitation of S(1) 18a(1) in p-fluorotoluene (pFT) at an internal energy of 845 cm(-1), where ?(18a) is a ring bending vibrational mode. Characteristic oscillations with periods of 8 ps and 5 ps are observed in the photoelectron signal and attributed to coupling between the initially excited zero-order bright state and two doorway states. Values for the coupling coefficients connecting these three vibrational states have been determined. In addition, an exponential change in photoelectron signal with a lifetime of 17 ps is attributed to weaker couplings with a bath of dark states that play a more significant role during the latter stages of IVR. A tier model has been used to assign the most strongly coupled doorway state to S(1) 17a(1) 6a(2)('), where ?(17a) is a CH out-of-plane vibrational mode and 6a(2)(') is a methyl torsional level. This assignment signifies that a torsion-vibration coupling mechanism mediates the observed dynamics, thus demonstrating the important role played by the methyl torsional mode in accelerating IVR. PMID:21974520

Davies, Julia A; Reid, Katharine L

2011-09-28

396

Evidence for direct CP violation in B±??h± and observation of B0??K0.  

PubMed

We report measurements of the branching fractions and CP asymmetries for B(±)??h(±) (h=K or ?) and the observation of the decay B(0)??K(0) from the final data sample of 772×10(6) B ?B pairs collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The measured branching fractions are B(B(±)??K(±))=(2.12±0.23±0.11)×10(-6), B(B(±)???(±))=(4.07±0.26±0.21)×10(-6), and B(B(0)??K(0))=(1.27(-0.29)(+0.33)±0.08)×10(-6), where the last decay is observed for the first time with a significance of 5.4 standard deviations (?). We also find evidence for CP violation in the charged B modes, A(CP)(B(±)??K(±))=-0.38±0.11±0.01 and A(CP)(B(±)???(±))=-0.19±0.06±0.01 with significances of 3.8 ? and 3.0 ?, respectively. For all measurements, the first and second uncertainties are statistical and systematic, respectively. PMID:22400727

Hoi, C-T; Chang, P; Aihara, H; Asner, D M; Aushev, T; Bakich, A M; Belous, K; Bhardwaj, V; Bhuyan, B; Bischofberger, M; Bondar, A; Bozek, A; Bra?ko, M; Browder, T E; Chang, M-C; Chao, Y; Chen, A; Chen, K-F; Chen, P; Cheon, B G; Chilikin, K; Cho, K; Choi, Y; Danilov, M; Drásal, Z; Drutskoy, A; Eidelman, S; Fast, J E; Gaur, V; Gabyshev, N; Goh, Y M; Golob, B; Haba, J; Hayasaka, K; Hoshi, Y; Hou, W-S; Hsiung, Y B; Hyun, H J; Inami, K; Ishikawa, A; Iwabuchi, M; Iwasaki, Y; Iwashita, T; Kang, J H; Kawasaki, T; Kim, H J; Kim, H O; Kim, J B; Kim, J H; Kim, K T; Kim, M J; Kinoshita, K; Ko, B R; Kobayashi, N; Kodyš, P; Korpar, S; Križan, P; Kuhr, T; Kumita, T; Kwon, Y-J; Lee, S-H; Li, J; Libby, J; Liu, Z Q; Louvot, R; Matvienko, D; McOnie, S; Miyabayashi, K; Miyata, H; Mohanty, G B; Moll, A; Nakano, E; Nakao, M; Neubauer, S; Nishida, S; Nishimura, K; Nitoh, O; Ohshima, T; Okuno, S; Park, C W; Park, H K; Pedlar, T K; Pestotnik, R; Petri?, M; Piilonen, L E; Ritter, M; Röhrken, M; Sahoo, H; Sakai, Y; Sanuki, T; Schneider, O; Schwanda, C; Schwartz, A J; Senyo, K; Sevior, M E; Shapkin, M; Shebalin, V; Shen, C P; Shibata, T-A; Shiu, J-G; Simon, F; Smerkol, P; Sohn, Y-S; Sokolov, A; Solovieva, E; Stari?, M; Sumihama, M; Tanaka, S; Tatishvili, G; Teramoto, Y; Trabelsi, K; Uchida, M; Uglov, T; Unno, Y; Uno, S; Varner, G; Wang, C H; Wang, M-Z; Wang, P; Watanabe, Y; Williams, K M; Won, E; Yamaoka, J; Yamashita, Y; Yusa, Y; Zhilich, V; Zupanc, A

2012-01-20

397

Observations of an Unusual Extended Nonthermal Radio Source in the Direction of the Galactic Center  

NASA Astrophysics Data System (ADS)

We present 20 and 90 cm VLA observations of an unusual extended nonthermal radio source near the galactic center, G359.87+0.44. This source was recently discovered on a wide-field VLA B-C-D 90 cm image of the galactic center (LaRosa et al 2000). It is located approximately 0.5\\arcdeg\\ northwest of Sgr A. Although the source morphology is somewhat different at 90 and 20 cm, the strongest emission comes from a linear structure with a length of 7\\arcmin similar to the nonthermal filaments also found in the GC region. However, the 20/90 cm spectral index (the spectral index ? of a source to be S ? ? , where S is its flux density and ? is its frequency) along the length of this source decreases uniformly from -0.6 to -1.4, in constrast to the constant (as a function of position) spectral indices exhibited by the nonthermal filaments. We present several alternative interpretations and plans for future observations. Basic research in radio astronomy at the NRL is supported by the Office of Naval Research. TNL acknowledges a NAVY-ASEE summer faculty fellowship at the NRL.

Kazi, T.; LaRosa, T. N.; Kassim, N.; Lazio, T. J. W.; Lang, C. C.; Anantharamaiah, K.

1999-12-01

398

Direct observation of hygiene in a Peruvian shantytown: not enough handwashing and too little water  

PubMed Central

Summary OBJECTIVE To document frequency of hygiene practices of mothers and children in a shantytown in Lima, Peru. METHODS Continuous monitoring over three 12-h sessions in households without in-house water connections to measure: (i) water and soap use of 32 mothers; (ii) frequency of interrupting faecal-hand contamination by washing; and (iii) the time until faecal-hand contamination became a possible transmission event. RESULTS During 1008 h of observation, 55% (65/119) of mothers’ and 69% (37/54) of children's faecal-hand contamination events were not followed within 15 min by handwashing or bathing. Nearly 40% (67/173) of faecal-hand contamination events became possible faecal-oral transmission events. There was no difference in the time-until-transmission between mothers and children (P = 0.43). Potential transmission of faecal material to food or mouth occurred in 64% of cases within 1 h of hand contamination. Mean water usage (6.5 l) was low compared to international disaster relief standards. CONCLUSIONS We observed low volumes of water usage, inadequate handwashing, and frequent opportunities for faecal contamination and possible transmission in this water-scarce community.

Oswald, William E.; Hunter, Gabrielle C.; Lescano, Andres G.; Cabrera, Lilia; Leontsini, Elli; Pan, William K.; Soldan, Valerie Paz; Gilman, Robert H.

2014-01-01

399

Intramolecular vibrational dynamics in S1 p-fluorotoluene. I. Direct observation of doorway states  

NASA Astrophysics Data System (ADS)

Picosecond time-resolved photoelectron spectroscopy is used to investigate intramolecular vibrational redistribution (IVR) following excitation of S1 18a1 in p-fluorotoluene (pFT) at an internal energy of 845 cm-1, where ?18a is a ring bending vibrational mode. Characteristic oscillations with periods of 8 ps and 5 ps are observed in the photoelectron signal and attributed to coupling between the initially excited zero-order bright state and two doorway states. Values for the coupling coefficients connecting these three vibrational states have been determined. In addition, an exponential change in photoelectron signal with a lifetime of 17 ps is attributed to weaker couplings with a bath of dark states that play a more significant role during the latter stages of IVR. A tier model has been used to assign the most strongly coupled doorway state to S1 17a1 6a2', where ?17a is a CH out-of-plane vibrational mode and 6a2' is a methyl torsional level. This assignment signifies that a torsion-vibration coupling mechanism mediates the observed dynamics, thus demonstrating the important role played by the methyl torsional mode in accelerating IVR.

Davies, Julia A.; Reid, Katharine L.

2011-09-01

400

A direct observation of solar neutrons following the 0118 UT flare on 1980 June 21  

NASA Technical Reports Server (NTRS)

The Gamma Ray Spectrometer on the Solar Maximum Mission satellite has observed energetic solar neutrons (greater than 50 MeV) at the earth following a solar flare that occurred on the west limb on June 21, 1980 at 01:18:20 UT. Impulsive photon emission from 10 keV to greater than 65 MeV lasting over a period of about 66 s was followed by a transient flux of 50-600 MeV neutrons incident over a 17 minute period. The peak counting rate corresponds to an average flux at the earth of (3.8 + or - 0.6) x 10 to the -2nd neutrons/sq cm s at 130 MeV. These observations indicate the emission of 3 x 10 to the 28th neutrons/sr with energies greater than 50 MeV, requiring the rapid acceleration (much less than 60 s) of protons to GeV energies during the impulsive phase of the flare.

Chupp, E. L.; Forrest, D. J.; Ryan, J. M.; Heslin, J.; Reppin, C.; Pinkau, K.; Kanbach, G.; Rieger, E.; Share, G. H.

1982-01-01