Sample records for allowing direct observation

  1. Direct chromatin PCR (DC-PCR): hypotonic conditions allow differentiation of chromatin states during thermal cycling.

    PubMed

    Vatolin, Sergei; Khan, Shahper N; Reu, Frederic J

    2012-01-01

    Current methods to study chromatin configuration are not well suited for high throughput drug screening since they require large cell numbers and multiple experimental steps that include centrifugation for isolation of nuclei or DNA. Here we show that site specific chromatin analysis can be achieved in one step by simply performing direct chromatin PCR (DC-PCR) on cells. The basic underlying observation was that standard hypotonic PCR buffers prevent global cellular chromatin solubilization during thermal cycling while more loosely organized chromatin can be amplified. Despite repeated heating to >90 °C, 41 of 61 tested 5' sequences of silenced genes (CDKN2A, PU.1, IRF4, FOSB, CD34) were not amplifiable while 47 could be amplified from expressing cells. Two gene regions (IRF4, FOSB) even required pre-heating of cells in isotonic media to allow this differentiation; otherwise none of 19 assayed sequences yielded PCR products. Cells with baseline expression or epigenetic reactivation gave similar DC-PCR results. Silencing during differentiation of CD34 positive cord blood cells closed respective chromatin while treatment of myeloma cells with an IRF4 transcriptional inhibitor opened a site to DC-PCR that was occupied by RNA polymerase II and NF?B as determined by ChIP. Translation into real-time PCR can not be achieved with commercial real-time PCR buffers which potently open chromatin, but even with simple ethidium bromide addition to standard PCR mastermix we were able to identify hits in small molecules screens that suppressed IRF4 expression or reactivated CDKN2A in myeloma cells using densitometry or visual inspection of PCR plates under UV light. While need in drug development inspired this work, application to genome-wide analysis appears feasible using phi29 for selective amplification of open cellular chromatin followed by library construction from supernatants since such supernatants yielded similar results as gene specific DC-PCR. PMID:22984542

  2. Observe how the monsoon changes direction

    NSDL National Science Digital Library

    TERC. Center for Earth and Space Science Education

    2003-01-01

    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

  3. Direct observations of solar-wind particles

    Microsoft Academic Search

    A. J. Hundhausen

    1968-01-01

    Direct observations of solar-wind particles are discussed in detail. A well-defined ‘quiet state’ of the solar wind is indicated by observations made from 1962 to 1967. The plasma properties in this quiet state are compared with those predicted by hydrodynamic models of the coronal expansion. While the basic flow parameters are predicted with reasonable accuracy by these models, the thermal

  4. Diffuse x-rays: Directly Observing Dark Matter?

    E-print Network

    Michael McNeil Forbes; Ariel R. Zhitnitsky

    2008-10-14

    Several independent observations of the Galactic core suggest hitherto unexplained sources of energy. We suggest that dark matter in the form of dense antimatter nuggets could provide a natural site for electron and proton annihilation, providing 511 keV photons, gamma-rays, and diffuse keV x-ray radiation. We show that identifying dark matter as antimatter nuggets is consistent with the observed emissions, and we make definite predictions about their spectrum and morphology. If correct, our proposal not only identifies dark matter and explains baryogenesis, but allows x-ray observations to directly probe the matter distribution in our Galaxy.

  5. First direct observation of muon antineutrino disappearance.

    PubMed

    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

    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

  6. First direct observation of muon antineutrino disappearance

    DOE PAGESBeta

    Adamson, P [Fermilab; Andreopoulos, C [Rutherford; Auty, D J [Sussex U.; Ayres, D S [Argonne; Backhouse, C [Oxford U.; Barr, G [Oxford U.; Bishai, M [Brookhaven; Blake, A [Cambridge U.; Bock, G J [Fermilab; Boehnlein, D J [/Fermilab; Bogert, D [Fermilab; Harvard U., Phys. Dept.

    2011-07-05

    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 x 1020 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 |?m?2| = (3.36-0.40 +0.46(stat.) ± 0.06(syst.)) x 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.

  7. 30 CFR 1220.011 - Schedule of allowable direct and allocable joint costs and credits.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...operations, or specific engineering design problems related to equipment or facilities...directly related to specific engineering design problems or alternatives for equipment...platforms and other facilities and in the restoration of the NPSL project area shall be...

  8. 30 CFR 220.011 - Schedule of allowable direct and allocable joint costs and credits.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...operations, or specific engineering design problems related to equipment or facilities...directly related to specific engineering design problems or alternatives for equipment...platforms and other facilities and in the restoration of the NPSL project area shall be...

  9. 30 CFR 1220.011 - Schedule of allowable direct and allocable joint costs and credits.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...operations, or specific engineering design problems related to equipment or facilities...directly related to specific engineering design problems or alternatives for equipment...platforms and other facilities and in the restoration of the NPSL project area shall be...

  10. 30 CFR 1220.011 - Schedule of allowable direct and allocable joint costs and credits.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...operations, or specific engineering design problems related to equipment or facilities...directly related to specific engineering design problems or alternatives for equipment...platforms and other facilities and in the restoration of the NPSL project area shall be...

  11. 30 CFR 1220.011 - Schedule of allowable direct and allocable joint costs and credits.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...operations, or specific engineering design problems related to equipment or facilities...directly related to specific engineering design problems or alternatives for equipment...platforms and other facilities and in the restoration of the NPSL project area shall be...

  12. Direct observation of sub-binomial light

    E-print Network

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

    2013-05-22

    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 quasi-probability 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. in Phys. Rev. Lett. 109, 093601 (2012). Our work paves a way for the practical characterisation of increasingly sophisticated states and detectors.

  13. Direct observation of sub-binomial light.

    PubMed

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

    2013-04-26

    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

  14. WMAP haze: Directly observing dark matter?

    SciTech Connect

    Forbes, Michael McNeil; Zhitnitsky, Ariel R. [Nuclear Theory Group, Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); University of British Columbia, Department of Physics and Astronomy, Vancouver, B.C., V6T 1Z1 (Canada)

    2008-10-15

    In this paper, we show that dark matter in the form of dense matter/antimatter nuggets could provide a natural and unified explanation for several distinct bands of diffuse radiation from the core of the Galaxy spanning over 13 orders of magnitude in frequency. We fix all of the phenomenological properties of this model by matching to x-ray observations in the keV band, and then calculate the unambiguously predicted thermal emission in the microwave band, at frequencies smaller by 11 orders of magnitude. Remarkably, the intensity and spectrum of the emitted thermal radiation are consistent with - and could entirely explain - the so-called 'WMAP haze': a diffuse microwave excess observed from the core of our Galaxy by the Wilkinson Microwave Anisotropy Probe (WMAP). This provides another strong constraint of our proposal, and a remarkable nontrivial validation. If correct, our proposal identifies the nature of the dark matter, explains baryogenesis, and provides a means to directly probe the matter distribution in our Galaxy by analyzing several different types of diffuse emissions.

  15. Directly observed therapy for treating tuberculosis

    PubMed Central

    Karumbi, Jamlick; Garner, Paul

    2015-01-01

    Background Tuberculosis (TB) requires at least six months of treatment. If treatment is incomplete, patients may not be cured and drug resistance may develop. Directly Observed Therapy (DOT) is a specific strategy, endorsed by the World Health Organization, to improve adherence by requiring health workers, community volunteers or family members to observe and record patients taking each dose. Objectives To evaluate DOT compared to self-administered therapy in people on treatment for active TB or on prophylaxis to prevent active disease. We also compared the effects of different forms of DOT. Search methods We searched the following databases up to 13 January 2015: the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE; EMBASE; LILACS and mRCT. We also checked article reference lists and contacted relevant researchers and organizations. Selection criteria Randomized controlled trials (RCTs) and quasi-RCTs comparing DOT with routine self-administration of treatment or prophylaxis at home. Data collection and analysis Two review authors independently assessed risk of bias of each included trial and extracted data. We compared interventions using risk ratios (RR) with 95% confidence intervals (CI). We used a random-effects model if meta-analysis was appropriate but heterogeneity present (I2 statistic = 50%). We assessed the quality of the evidence using the GRADE approach. Main results Eleven trials including 5662 participants met the inclusion criteria. DOT was performed by a range of people (nurses, community health workers, family members or former TB patients) in a variety of settings (clinic, the patient's home or the home of a community volunteer). DOT versus self-administered Six trials from South Africa, Thailand, Taiwan, Pakistan and Australia compared DOT with self-administered therapy for treatment. Trials included DOT at home by family members, community health workers (who were usually supervised); DOT at home by health staff; and DOT at health facilities. TB cure was low with self-administration across all studies (range 41% to 67%), and direct observation did not substantially improve this (RR 1.08, 95% CI 0.91 to 1.27; five trials, 1645 participants, moderate quality evidence). In a subgroup analysis stratified by the frequency of contact between health services in the self-treatment arm, daily DOT may improve TB cure when compared to self-administered treatment where patients in the self-administered group only visited the clinic every month (RR 1.15, 95% CI 1.06 to 1.25; two trials, 900 participants); but with contact in the control becoming more frequent, this small effect was not apparent (every two weeks: RR 0.96, 95% CI 0.83 to 1.12; one trial, 497 participants; every week: RR 0.90, 95% CI 0.68 to 1.21; two trials, 248 participants). Treatment completion showed a similar pattern, ranging from 59% to 78% in the self-treatment groups, and direct observation did not improve this (RR 1.07, 95% CI 0.96 to 1.19; six trials, 1839 participants, moderate quality evidence). DOT at home versus DOT at health facility In four trials that compared DOT at home by family members, or community health workers, with DOT by health workers at a health facility there was little or no difference in cure or treatment completion (cure: RR 1.02, 95% CI 0.88 to 1.18, four trials, 1556 participants, moderate quality evidence; treatment completion: RR 1.04, 95% CI 0.91 to 1.17, three trials, 1029 participants, moderate quality evidence). DOT by family member versus DOT by community health worker Two trials compared DOT at home by family members with DOT at home by community health workers. There was also little or no difference in cure or treatment completion (cure: RR 1.02, 95% CI 0.86 to 1.21; two trials, 1493 participants, moderate quality evidence; completion: RR 1.05, 95% CI 0.90 to 1.22; two trials, 1493 participants, low quality evidence). Specific patient categories A trial of 300 intravenous drug users in the USA

  16. New directions in childhood obesity research: how a comprehensive biorepository will allow better prediction of outcomes

    PubMed Central

    2010-01-01

    Background Childhood obesity is associated with the early development of diseases such as type 2 diabetes and cardiovascular disease. Unfortunately, to date, traditional methods of research have failed to identify effective prevention and treatment strategies, and large numbers of children and adolescents continue to be at high risk of developing weight-related disease. Aim To establish a unique 'biorepository' of data and biological samples from overweight and obese children, in order to investigate the complex 'gene × environment' interactions that govern disease risk. Methods The 'Childhood Overweight BioRepository of Australia' collects baseline environmental, clinical and anthropometric data, alongside storage of blood samples for genetic, metabolic and hormonal profiles. Opportunities for longitudinal data collection have also been incorporated into the study design. National and international harmonisation of data and sample collection will achieve required statistical power. Results Ethical approval in the parent site has been obtained and early data indicate a high response rate among eligible participants (71%) with a high level of compliance for comprehensive data collection (range 56% to 97% for individual study components). Multi-site ethical approval is now underway. Conclusions In time, it is anticipated that this comprehensive approach to data collection will allow early identification of individuals most susceptible to disease, as well as facilitating refinement of prevention and treatment programs. PMID:20969745

  17. Direct observation of stepwise movement of a synthetic molecular transporter

    NASA Astrophysics Data System (ADS)

    Wickham, Shelley F. J.; Endo, Masayuki; Katsuda, Yousuke; Hidaka, Kumi; Bath, Jonathan; Sugiyama, Hiroshi; Turberfield, Andrew J.

    2011-03-01

    Controlled motion at the nanoscale can be achieved by using Watson-Crick base-pairing to direct the assembly and operation of a molecular transport system consisting of a track, a motor and fuel, all made from DNA. Here, we assemble a 100-nm-long DNA track on a two-dimensional scaffold, and show that a DNA motor loaded at one end of the track moves autonomously and at a constant average speed along the full length of the track, a journey comprising 16 consecutive steps for the motor. Real-time atomic force microscopy allows direct observation of individual steps of a single motor, revealing mechanistic details of its operation. This precisely controlled, long-range transport could lead to the development of systems that could be programmed and routed by instructions encoded in the nucleotide sequences of the track and motor. Such systems might be used to create molecular assembly lines modelled on the ribosome.

  18. Direct observation of microbubbles in directional solidification of salol

    Microsoft Academic Search

    Lloyd M. Williams; M. R. Srinivasan; Herman Z. Cummins

    1990-01-01

    Dynamic light scattering at the crystal-melt interface of solidifying salol was followed for 14 days. The hydrodynamic radius deduced from intensity correlation data increased continuously from ~1 to ~100 mum. When the scattering layer was trapped by the advancing crystal front, microscopic observation revealed bubbles as inclusions whose size agreed with the light-scattering value. Scattering was also observed to disappear

  19. Direct observation of microbubbles in directional solidification of salol

    Microsoft Academic Search

    Lloyd Williams; M. R. Srinivasan; Herman Cummins

    1990-01-01

    Dynamic light scattering at the crystal-melt interface of solidifying salol was followed for 14 days. The hydrodynamic radius deduced from intensity correlation data increased continuously from â1 to â100 μm. When the scattering layer was trapped by the advancing crystal front, microscopic observation revealed bubbles as inclusions whose size agreed with the light-scattering value. Scattering was also observed to disappear

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

    PubMed

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

    2014-06-01

    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

  1. Direct observation of ballistic Andreev reflection

    NASA Astrophysics Data System (ADS)

    Klapwijk, T. M.; Ryabchun, S. A.

    2014-12-01

    An overview is presented of experiments on ballistic electrical transport in inhomogeneous superconducting systems which are controlled by the process of Andreev reflection. The initial experiments based on the coexistence of a normal phase and a superconducting phase in the intermediate state led to the concept itself. It was followed by a focus on geometrically inhomogeneous systems like point contacts, which provided a very clear manifestation of the energy and direction dependence of the Andreev reflection process. The point contacts have recently evolved towards the atomic scale owing to the use of mechanical break-junctions, revealing a very detailed dependence of Andreev reflection on the macroscopic phase of the superconducting state. In present-day research, the superconducting in homogeneity is constructed by clean room technology and combines superconducting materials, for example, with low-dimensional materials and topological insulators. Alternatively, the superconductor is combined with nano-objects, such as graphene, carbon nanotubes, or semiconducting nanowires. Each of these "inhomogeneous systems" provides a very interesting range of properties, all rooted in some manifestation of Andreev reflection.

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

    PubMed Central

    Srivastava, Shivani; Koch, Meghan A.; Pepper, Marion

    2014-01-01

    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

  3. Direct Observation of Two Proton Radioactivity Using Digital Photography

    SciTech Connect

    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

    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.

  4. Combined use of leaf size and economics traits allows direct comparison of hydrophyte and terrestrial herbaceous adaptive strategies

    PubMed Central

    Pierce, Simon; Brusa, Guido; Sartori, Matteo; Cerabolini, Bruno E. L.

    2012-01-01

    Background and Aims Hydrophytes generally exhibit highly acquisitive leaf economics. However, a range of growth forms is evident, from small, free-floating and rapidly growing Lemniden to large, broad-leaved Nymphaeiden, denoting variability in adaptive strategies. Traits used to classify adaptive strategies in terrestrial species, such as canopy height, are not applicable to hydrophytes. We hypothesize that hydrophyte leaf size traits and economics exhibit sufficient overlap with terrestrial species to allow a common classification of plant functional types, sensu Grime's CSR theory. Methods Leaf morpho-functional traits were measured for 61 species from 47 water bodies in lowland continental, sub-alpine and alpine bioclimatic zones in southern Europe and compared against the full leaf economics spectrum and leaf size range of terrestrial herbs, and between hydrophyte growth forms. Key Results Hydrophytes differed in the ranges and mean values of traits compared with herbs, but principal components analysis (PCA) demonstrated that both groups shared axes of trait variability: PCA1 encompassed size variation (area and mass), and PCA2 ranged from relatively dense, carbon-rich leaves to nitrogen-rich leaves of high specific leaf area (SLA). Most growth forms exhibited trait syndromes directly equivalent to herbs classified as R adapted, although Nymphaeiden ranged between C and SR adaptation. Conclusions Our findings support the hypothesis that hydrophyte adaptive strategy variation reflects fundamental trade-offs in economics and size that govern all plants, and that hydrophyte adaptive strategies can be directly compared with terrestrial species by combining leaf economics and size traits. PMID:22337079

  5. Plasmon Surface Polariton Dispersion by Direct Optical Observation.

    ERIC Educational Resources Information Center

    Swalen, J. D.; And Others

    1980-01-01

    Describes several simple experiments that can be used to observe directly the dispersion curve of plasmon surface polaritons (PSP) on flat metal surfaces. A method is described of observing the increonental change in the wave vector of the PSP due to coatings that differ in thickness by a few nanometers. (Author/CS)

  6. Direct observation of the structural isomerization of a cationic group 4 Ziegler-Natta insertion product.

    PubMed

    Keaton, Richard J; Sita, Lawrence R

    2002-08-01

    An experimental model that allows for direct observation of a structural isomerization that is relevant to the group 4 metal-mediated Ziegler-Natta polymerization of alpha-olefins is presented. More specifically, several features of this system are consistent with current theories presented for chain epimerization that occurs during propene polymerization. PMID:12149009

  7. An attempt to observe directly beauty particles in nuclear emulsions

    NASA Astrophysics Data System (ADS)

    Albanese, J. P.; Allasia, D.; Armenise, N.; Arnold, R.; Baroni, G.; Barth, M.; Bertrand, D.; Bertrand-Coremans, G.; Bisi, V.; Breslin, A. C.; Calicchio, M.; Coupland, M.; Davis, D. G.; Davis, D. H.; Di Ciaccio, L.; Di Liberto, S.; Downes, J. K.; Duff, B. G.; Erriquez, O.; Esten, M. J.; Gamba, D.; Gjerpe, I.; Hazama, M.; Heymann, F. F.; Hoshino, K.; Imrie, D. C.; Isokane, Y.; Lavopa, P.; Lush, G. J.; Maeda, Y.; Maggi, G.; Manfredini, A.; Marzari-Chiesa, A.; Matteuzzi, C.; Meddi, F.; Miyanishi, M.; Montwill, A.; Muciaccia, M. T.; Musset, P.; Nakamura, M.; Natali, S.; Niu, K.; Niwa, K.; Nuzzo, S.; O'Connor, A.; Ohashi, M.; Petrera, S.; Piuz, F.; Poulard, G.; Price, M. J.; Ramello, L.; Riccati, L.; Roberts, I.; Romano, F.; Romano, G.; Romero, A.; Roosen, R.; Rosa, G.; Ruggieri, F.; Sacton, J.; Santonico, R.; Sato, Y.; Schorochoff, G.; Sebastiani, F.; Shibuya, H.; Sletten, H.; Stannard, F. R.; Tasaka, S.; Tezuka, I.; Tovee, D. N.; Trent, P.; Tsuneoka, Y.; Ushida, N.; Wickens, J.; Yamakawa, O.; Yanagisawa, N.; NA19 Collaboration

    1983-03-01

    An attempt at the direct observation of the cascade decay of beauty particles, produced by ?- of 350 GeV/ c leading to 3 muons or 4 muons in the final state, has been made in an emulsion/counter hybrid experiment at CERN. Under the assumption that the lifetime of beauty particles is of the order of 10 -13s the non-observation of any candidates provides an upper limit for beauty production of ?90 nb at the 90% confidence level.

  8. Direct Observations of Reaction Zone Structure in Propagating Detonations

    E-print Network

    Barr, Al

    Direct Observations of Reaction Zone Structure in Propagating Detonations F. Pintgen, C.A. Eckett 1 of self-sustaining, cellular detonations propagating near the Chapman-Jouguet state in hydrogen- oxygen propagating transversely to the main front. As a consequence, the reaction zone region is spatially nonuniform

  9. Direct Observation of Nanoscale Switching Centers in Metal/Molecule/

    E-print Network

    Bockrath, Marc

    , with zero-bias resistance typically >105 . The devices can be switched reVersibly and repeatedly to higherDirect Observation of Nanoscale Switching Centers in Metal/Molecule/ Metal Structures Chun Ning Lau switching in metal/molecule/metal structures has attracted tremendous and broad interest. Understanding

  10. Direct observations of blob deformation during a substorm

    NASA Astrophysics Data System (ADS)

    Ishida, T.; Ogawa, Y.; Kadokura, A.; Hosokawa, K.; Otsuka, Y.

    2015-05-01

    Ionospheric blobs are localized plasma density enhancements, which are mainly produced by the transportation process of plasma. To understand the deformation process of a blob, observations of plasma parameters with good spatial-temporal resolution are desirable. Thus, we conducted the European Incoherent Scatter radar observations with high-speed meridional scans (60-80 s) during October and December 2013, and observed the temporal evolution of a blob during a substorm on 4 December 2013. This paper is the first report of direct observations of blob deformation during a substorm. The blob deformation arose from an enhanced plasma flow shear during the substorm expansion phase, and then the blob split into two smaller-scale blobs, whose scale sizes were more than ~100 km in latitude. Our analysis indicates that the Kelvin-Helmholtz instability and dissociative recombination could have deformed the blob structure.

  11. Direct observation of the vortex core magnetization and itsdynamics

    SciTech Connect

    Chou, K.W.; Puzic, A.; Stoll, H.; Dolgos, D.; Schutz, G.; VanWaeyenberge, B.; Vansteenkiste, A.; Tyliszczak, Tolek; Woltersdorf, G.; Back, C.H.

    2007-04-18

    Square-shaped thin film structures with a single magneticvortex were investigated using a scanning transmission x-ray microscope.The authors report on the direct observation of the vortex core in500x500 nm2, 40 nm thick soft magnetic Ni Fe samples. The staticconfiguration of the vortex core was imaged as well as the gyrotropicmotion of the core under excitation with an in-plane alternating magneticfield. This enabled them to directly visualize the direction of theout-of-plane magnetization in the up or dow. The reversal of the core waseffected by short bursts of an alternating magnetic field. An asymmetryappears in the core s trajectory for its orientation pointing up anddown, respectively.

  12. Direct Observation of Thymine Dimer Repair in DNA by Photolyase

    NASA Astrophysics Data System (ADS)

    Zhong, Dongping

    2006-03-01

    Departments of Physics, Chemistry, and Biochemistry, Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University, Columbus, 191 West Woodruff Avenue, OH 43210. Photolyase uses light energy to split ultraviolet-induced cyclobutane pyrimidine dimers in damaged DNA, but its molecular mechanism has never been directly revealed. We report here the direct mapping of catalytic processes through femtosecond synchronization of the enzymatic dynamics with the repair function. We observed direct electron transfer from the excited flavin cofactor to the dimer in 170 ps and back electron transfer from the repaired thymines in 560 ps. Both reactions are strongly modulated by active-site solvation to achieve maximum repair efficiency. These results show that the photocycle of DNA repair by photolyase is through a radical mechanism and completed on subnanosecond time scale at the dynamic active site with no net electron change in redox states of the flavin cofactor.

  13. The temperature distribution within a sphere placed in a directed uniform heat flux and allowed to radiatively cool

    NASA Technical Reports Server (NTRS)

    Duffy, D.

    1985-01-01

    The temperature field within a sphere is found when the sphere is heated by a directed heat flux and cooled by blackbody radiation. For small heat fluxes, the analytic solution is obtained by transform methods. For large heat fluxes, the solution is computed numerically.

  14. Direct observation of single kinesin molecules moving along microtubules

    Microsoft Academic Search

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

    1996-01-01

    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

  15. Direct observations of reaction zone structure in propagating detonations

    Microsoft Academic Search

    F. Pintgen; C. A. Eckett; J. M. Austin; J. E. Shepherd

    2003-01-01

    We report experimental observations of the reaction zone structure of self-sustaining, cellular detonations propagating near the Chapman-Jouguet state in hydrogen-oxygen-argon\\/nitrogen mixtures. Two-dimensional cross sections perpendicular to the propagation direction were imaged using the technique of planar laser induced fluorescence (PLIF) and, in some cases, compared to simultaneously acquired schlieren images. Images are obtained which clearly show the nature of the

  16. Direct observation of tetrahedral hydrogen jumps in ice Ih

    Microsoft Academic Search

    F. Fujara; S. Wefing; W. F. Kuhs

    1988-01-01

    Using deuteron NMR, spin alignment tetrahedral jumps of 2H in deuterated polycrystalline hexagonal ice (Ih) have been observed. Both geometry and time scale of the process are determined directly. At T=230 K the correlation time of these jumps is 0.21(3) ms. The tetrahedral hydrogen jumps turn out to scatter—most characteristically for the disorder within the hydrogen subsystem—randomly about the tetrahedral

  17. Responses to the advanced notice of proposed rulemaking EPA published on June 6, 1996 regarding changes to the EPA allowance auctions and elimination of the direct sale

    SciTech Connect

    Critchfield, L.R. [EPA Acid Rain Division, Washington, DC (United States)

    1997-12-31

    On June 6, 1996, EPA`s Acid Rain Program published an advance notice of proposed rulemaking (ANPRM) in the Federal Register seeking comment on: (1) whether to change the design of the annual sulfur dioxide (SO{sub 2}) allowance auctions; (2) whether to change the timing of the allowance auctions; (3) whether to change the requirement that the minimum price of offered allowances must be in whole dollars, and (4) whether EPA should propose the ability to submit allowance transfers electronically. EPA also published on that day a proposed and direct final rule on whether to eliminate the direct sale. This paper documents the issues addressed in the ANPRM, the comments EPA received, and EPA`s responses to those comments. EPA received comments from 14 separate commenters.

  18. Microcrack closure in rocks under stress - Direct observation

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    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

  19. Direct Observation of Correlated Interdomain Motion in Alcohol Dehydrogenase

    NASA Astrophysics Data System (ADS)

    Biehl, Ralf; Hoffmann, Bernd; Monkenbusch, Michael; Falus, Peter; Préost, Sylvain; Merkel, Rudolf; Richter, Dieter

    2008-09-01

    Interdomain motions in proteins are essential to enable or promote biochemical function. Neutron spin-echo spectroscopy is used to directly observe the domain dynamics of the protein alcohol dehydrogenase. The collective motion of domains as revealed by their coherent form factor relates to the cleft opening dynamics between the binding and the catalytic domains enabling binding and release of the functional important cofactor. The cleft opening mode hardens as a result of an overall stiffening of the domain complex due to the binding of the cofactor.

  20. Direct observation of thitherto unobservable quantum phenomena by using electrons

    PubMed Central

    Tonomura, Akira

    2005-01-01

    Fundamental aspects of quantum mechanics, which were discussed only theoretically as “thought experiments” in the 1920s and 1930s, have begun to frequently show up in nanoscopic regions owing to recent rapid progress in advanced technologies. Quantum phenomena were once regarded as the ultimate factors limiting further miniaturization trends of microstructured electronic devices, but now they have begun to be actively used as the principles for new devices such as quantum computers. To directly observe what had been unobservable quantum phenomena, we have tried to develop bright and monochromatic electron beams for the last 35 years. Every time the brightness of an electron beam improved, fundamental experiments in quantum mechanics became possible, and quantum phenomena became observable by using the wave nature of electrons. PMID:16150719

  1. Direct Observations of PMC Local Time Variations by Aura OMI

    NASA Technical Reports Server (NTRS)

    DeLand, Matthew T.; Shettle, Eric P.; Thomas, Gary E.; Olivero, John J.

    2010-01-01

    The Ozone Monitoring Instrument (OMI) on the Aura satellite obtains unique measurements for polar mesospheric cloud (PMC) analysis. Its wide cross-track viewing swath and high along-track spatial resolution makes it possible to directly evaluate PMC occurrence frequency and brightness variations between 6S" and 8S' latitude as a function of local time over a 12-14 h continuous period. OMI PMC local time variations are closely coupled to concurrent variations in measurement scattering angle, so that ice phase function effects must be considered when interpreting the observations. Two different phase functions corresponding to bright and faint clouds are examined in this analysis. OMI observations show maximum frequency and albedo values at 8-10 h local time in the Northern Hemisphere, with decreasing amplitude at higher latitudes. Southern Hemisphere values reach a minimum at 18-20 h LT. Larger variations are seen in Northern Hemisphere data. No statistically significant longitudinal dependence was seen.

  2. Direct observation of small cluster mobility and ripening

    NASA Technical Reports Server (NTRS)

    Heinemann, K.; Poppa, H.

    1976-01-01

    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 have been studied by in situ transmission electron microscopy (TEM) under controlled environmental conditions in the temperature range from 25 to 450 C. It was possible to monitor all stages of the experiments by TEM observation of the same specimen area. Slow Ostwald ripening was found to occur over the entire temperature range, but the overriding surface transport mechanism was short-distance cluster mobility. This was concluded from in situ observations of individual particles during annealing and from measurements of cluster size distributions, cluster number densities, area coverages, and mean cluster diameters.

  3. Evidence of Arctic sea ice thinning from direct observations

    NASA Astrophysics Data System (ADS)

    Renner, Angelika H. H.; Gerland, Sebastian; Haas, Christian; Spreen, Gunnar; Beckers, Justin F.; Hansen, Edmond; Nicolaus, Marcel; Goodwin, Harvey

    2014-07-01

    The Arctic sea ice cover is rapidly shrinking, but a direct, longer-term assessment of the ice thinning remains challenging. A new time series constructed from in situ measurements of sea ice thickness at the end of the melt season in Fram Strait shows a thinning by over 50% during 2003-2012. The modal and mean ice thickness along 79°N decreased at a rate of 0.3 and 0.2 m yr-1, respectively, with long-term averages of 2.5 and 3 m. Airborne observations reveal an east-west thickness gradient across the strait in spring but not in summer due to advection from more different source regions. There is no clear relationship between interannual ice thickness variability and the source regions of the ice. The observed thinning is therefore likely a result of Arctic-wide reduction in ice thickness with a potential shift in exported ice types playing a minor role.

  4. Direct observation of capacitor switching using planar electrodes

    SciTech Connect

    Balke, Nina [ORNL; Gajek, Martin [University of California, Berkeley; Tagantsev, ALexander [EPFL, Lausanne, Switzerland; Martin, Lane W. W. [University of California, Berkeley; Chu, Ying-Hao [National Chiao Tung University, Hsinchu, Taiwan; Ramesh, R. [University of California, Berkeley; Kalinin, Sergei V [ORNL

    2010-01-01

    Ferroelectric polarization switching in epitaxial (110) BiFeO{sub 3} films is studied using piezoresponse force microscopy of a model in-plane capacitor structure. The electrode orientation is chosen such that only two active domain variants exist. Studies of the kinetics of domain evolution allows clear visualization of nucleation sites, as well as forward and lateral growth stages of domain formation. It is found that the location of the reverse-domain nucleation is correlated with the direction of switching in a way that the polarization in the domains nucleated at an electrode is always directed away from it. The role of interface charge injection and surface screening charge on switching mechanisms is explored, and the nucleation is shown to be controllable by the bias history of the sample. Finally, the manipulation of domain nucleation through domain structure engineering is illustrated. These studies pave the way for the engineering and design of the ferroelectric device structures through control of individual steps of the switching process.

  5. Direct observation of photoinduced bent nitrosyl excited-state complexes

    SciTech Connect

    Sawyer, Karma R.; Steele, Ryan P.; Glascoe, Elizabeth A.; Cahoon, James F.; Schlegel, Jacob P.; Head-Gordon, Martin; Harris, Charles B.

    2008-06-28

    Ground state structures with side-on nitrosyl ({eta}{sup 2}-NO) and isonitrosyl (ON) ligands have been observed in a variety of transition-metal complexes. In contrast, excited state structures with bent-NO ligands have been proposed for years but never directly observed. Here we use picosecond time-resolved infrared spectroscopy and density functional theory (DFT) modeling to study the photochemistry of Co(CO){sub 3}(NO), a model transition-metal-NO compound. Surprisingly, we have observed no evidence for ON and {eta}{sup 2}-NO structural isomers, but have observed two bent-NO complexes. DFT modeling of the ground and excited state potentials indicates that the bent-NO complexes correspond to triplet excited states. Photolysis of Co(CO){sub 3}(NO) with a 400-nm pump pulse leads to population of a manifold of excited states which decay to form an excited state triplet bent-NO complex within 1 ps. This structure relaxes to the ground triplet state in ca. 350 ps to form a second bent-NO structure.

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

    PubMed

    Shrivastava, Saurabh Rambiharilal; Shrivastava, Prateek Saurabh; Ramasamy, Jegadeesh

    2014-01-01

    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. PMID:24596899

  7. Compassionate Allowances

    MedlinePLUS

    ... The hearings were on rare diseases, cancers, traumatic brain injury (TBI) and stroke, early-onset Alzheimer's disease and related dementias, schizophrenia, cardiovascular disease and multiple organ transplants and autoimmune diseases. Contact the Compassionate Allowances Team ...

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

    PubMed Central

    2014-01-01

    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. PMID:24886143

  9. Direct observation of electron confinement in epitaxial graphene nanoislands.

    PubMed

    Phark, Soo-Hyon; Borme, Jérôme; Vanegas, Augusto León; Corbetta, Marco; Sander, Dirk; Kirschner, Jürgen

    2011-10-25

    One leading question for the application of graphene in nanoelectronics is how electronic properties depend on the size at the nanoscale. Direct observation of the quantized electronic states is central to conveying the relationship between electronic structures and local geometry. Scanning tunneling spectroscopy was used to measure differential conductance dI/dV patterns of nanometer-size graphene islands on an Ir(111) surface. Energy-resolved dI/dV maps clearly show a spatial modulation, indicating a modulated local density of states due to quantum confinement, which is unaffected by the edge configuration. We establish the energy dispersion relation with the quantized electron wave vector obtained from a Fourier analysis of dI/dV maps. The nanoislands preserve the Dirac Fermion properties with a reduced Fermi velocity. PMID:21942619

  10. Direct Observation of Acoustic Oscillations in InAs Nanowires

    SciTech Connect

    Mariager, Simon O.; Khakhulin, Dmitry; Lemke, Henrik T.; Kjær, Kasper S.; Guerin, Laurent; Nuccio, Laura; Sørensen, Claus B.; Nielsen, Martin M.; Feidenhans’ l, Robert (Copenhagen); (ESRF)

    2010-09-02

    Time-resolved X-ray diffraction and optical reflectivity are used to directly measure three different acoustic oscillations of InAs nanowires. The oscillations are excited by a femtosecond laser pulse and evolve at three different time scales. We measure the absolute scale of the initial radial expansion of the fundamental breathing eigenmode and determine the frequency by transient optical reflectivity. For the extensional eigenmode we measure the oscillations of the average radial and axial lattice constants and determine the amplitude of oscillations and the average extension. Finally we observe a bending motion of the nanowires. The frequencies of the eigenmodes are in good agreements with predictions made by continuum elasticity theory and we find no difference in the speed of sound between the wurtzite nanowires and cubic bulk crystals, but the measured strain is influenced by the interaction between different modes. The wurtzite crystal structure of the nanowires however has an anisotropic thermal expansion.

  11. Direct observation of the CRAND proton radiation belt source

    NASA Astrophysics Data System (ADS)

    Selesnick, R. S.; Hudson, M. K.; Kress, B. T.

    2013-12-01

    Observations of geomagnetically trapped 27-45 MeV protons following the November 2003 magnetic storm show a gradual intensity rise that is interpreted as a direct measurement of the cosmic ray albedo neutron decay (CRAND) source strength. The intensity rise is simulated by combining the detector response function with a model CRAND source, obtained by drift-averaging neutron intensity from Monte Carlo simulation of cosmic ray interactions in the atmosphere. The simulation, for 2.4

  12. Enabling direct nanoscale observations of biological reactions with dynamic TEM

    PubMed Central

    Evans, James E.; Browning, Nigel D.

    2013-01-01

    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. PMID:23315566

  13. Direct observation of ordered configurations of hydrogen adatoms on graphene

    NASA Astrophysics Data System (ADS)

    Lin, Chenfang; Feng, Yexin; Xiao, Yingdong; Duerr, Michael; Huang, Xiangqian; Xu, Xiaozhi; Zhao, Ruguang; Wang, Enge; Li, Xin-Zheng; Hu, Zonghai

    2015-03-01

    Ordered configurations of hydrogen adatoms on graphene have received great attention because they are closely tied to tuning of graphene properties including large band gap opening and formation of specific magnetic orders, both of which are highly desirable in potential applications. Many ordered structures of hydrogenated graphene have been proposed, including double sided and single sided ones, with the calculated band gap width depending on the respective H coverage. However, none of these ordered structures has been observed directly. Here we report direct imaging of several ordered configurations of H adatoms on graphene by scanning tunneling microscopy. The H atoms in the configurations exhibit apparent sublattice selectivity and tiny deviations from the exact atop-of-carbon positions. Scanning tunneling spectroscopy measurements of the configurations showed a larger than 0.6 eV gap in the local density of states. These findings can be well explained by our density functional theory simulations based on models of double sided H configurations. Z. H. thanks the NBRP of China (Grant 2012CB921300) and the Chinese Ministry of Education for financial supports. E. W., X. Z. L. and Z. H. thank the National Natural Science Foundation of China (Grant 11074005, 91021007 and 11275008) for financial supports.

  14. Direct observation of electron dynamics in the attosecond domain.

    PubMed

    Föhlisch, A; Feulner, P; Hennies, F; Fink, A; Menzel, D; Sanchez-Portal, D; Echenique, P M; Wurth, W

    2005-07-21

    Dynamical processes are commonly investigated using laser pump-probe experiments, with a pump pulse exciting the system of interest and a second probe pulse tracking its temporal evolution as a function of the delay between the pulses. Because the time resolution attainable in such experiments depends on the temporal definition of the laser pulses, pulse compression to 200 attoseconds (1 as = 10(-18) s) is a promising recent development. These ultrafast pulses have been fully characterized, and used to directly measure light waves and electronic relaxation in free atoms. But attosecond pulses can only be realized in the extreme ultraviolet and X-ray regime; in contrast, the optical laser pulses typically used for experiments on complex systems last several femtoseconds (1 fs = 10(-15) s). Here we monitor the dynamics of ultrafast electron transfer--a process important in photo- and electrochemistry and used in solid-state solar cells, molecular electronics and single-electron devices--on attosecond timescales using core-hole spectroscopy. We push the method, which uses the lifetime of a core electron hole as an internal reference clock for following dynamic processes, into the attosecond regime by focusing on short-lived holes with initial and final states in the same electronic shell. This allows us to show that electron transfer from an adsorbed sulphur atom to a ruthenium surface proceeds in about 320 as. PMID:16034414

  15. Direct observation of the spin-dependent Peltier effect.

    PubMed

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

    2012-03-01

    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

  16. THEMIS Observations of Directly-Driven Pi2 Pulsations

    NASA Technical Reports Server (NTRS)

    Kepko, L.; Angelopoulos, V.; Russell, C. T.; Yumoto, K.; Singer, H.; Glassmeier, K.-H.; McFadden, J.

    2010-01-01

    The THEMIS tail seasons have provided an unprecedented opportunity to examine the causal relationship between midtail plasma flows and low latitude Pi2 pulsations. We present several events where multiple THEMIS spacecraft observed magnetotail flow bursts which were followed up to several minutes later by ground Pi2 pulsations. We find good agreement with the waveforms of the flow bursts and flank Pi2, in agreement with the hypothesis that Pi2 at low-latitude on the flank are directly-driven by periodic variations in the flow bursts. For at least I event we are able to follow the Pi2 impulses from the periodic flow bursts on the nightside. to ground Pi2 at the flanks, and finally through the dayside magnetosphere as observed by GOES. We further place the physical mechanism generating these Pi2 into the context of sub storm onset. We conclude by discussing the sequence and coupling of events that are necessary to explain the correlation, and the constraints this places on models of transient magnetospheric transport.

  17. Direct Observation, Study, and Control of Molecular Superrotors

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  18. Direct observation, study and control of molecular super rotors

    NASA Astrophysics Data System (ADS)

    Korobenko, Aleksey; Milner, Alexander; Hepburn, John; Milner, Valery

    2014-05-01

    Extremely fast rotating molecules whose rotational energy is comparable with or exceeds the molecular bond strength are known as ``super rotors''. It has been speculated that super rotors may exhibit a number of unique properties, yet only indirect evidence of these molecular objects has been reported to date. We demonstrate the first direct observation of molecular super rotors 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 ultra-broad 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 super rotors can be created and observed in dense samples under normal conditions where the effects of ultrafast rotation on many-body interactions, inter-molecular collisions and chemical reactions can be readily explored.

  19. Geoelectrical and colour tracer monitoring with direct push observation wells

    NASA Astrophysics Data System (ADS)

    Dietrich, P.; Dietze, M.; Hoffmann, R.

    2003-04-01

    Borehole - borehole tracer tests are a hydrogeological method to characterize groundwater flow parameters. Breakthrough curves of colour tracers, injected in one borehole and measured in one or more observation wells downstream of the first, give exact but locally very limited information about groundwater flow direction and velocity. At heterogeneous subsurface conditions a large number of investigation wells and frequent sample drawing is necessary to assure recovery of the tracer, which makes the experiments very expensive. Yet, these experiments often fail or do not give sufficient information about the flow regime in the aquifer. Monitoring of salt tracers with geoelectrical methods gives an integral information about flow parameters which in most cases is a more useful information. Especially in deeper aquifers though, it is a problem to place a high number of electrodes close enough to the moving tracer to gain precise results. To assess the mentioned problems we carried out a combined geoelectrical salt and conventional colour tracer test. Our equipment for both tests was placed in direct push boreholes, which are a lot cheaper than groundwater wells, quickly installed and much less invasive. The boreholes were installed at 10 meters distance on a 120 m long profile, to form a control plane 25 meters downstream of the tracer injection. The injection took place in three different groundwater wells at a time, to provide for a good overview of the flow regime along the control plane. We show, how integral information from the geoelectrical tracer tests can be used to design a refined borehole placement for a successful colour tracer test. Our results, quite different from groundwater modelling results, strongly support the necessity to carry out precise field tracer tests for the investigation of groundwater flow parameters.

  20. Microcrack closure in rocks under stress: direct observation

    SciTech Connect

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

    1980-12-10

    Microcrack closure in rocks under increasing stress was observed directly with a scanning electron microscope. Uniaxial stresses to 300 bars were applied with a small hydraulic press to specimens of Westerly (RI) granite, both unheated and previously heat cycled to 500/sup 0/C, and of Frederick (MD) diabase, heat cycled to 700/sup 0/C. Closure characteristics (rate, final closure pressure, etc.) depend on crack orientation, shape, surface roughness, and on the nature of fracture intersections and interactions. Cracks perpendicular to the applied stress closed while those parallel to the stress tended to open. Long, narrow cracks (low aspect ratio) closed at relatively low pressures. At some intersections, one fracture would open while another simultaneously closed, depending upon their orientations. Many fractures closed uniformly even though offset by other fractures. Local stress concentrations often caused new fracturing at low applied stress. Some fractures were propped open until material lodged inside was crushed. Significant irreversible damage occurred during the first stress cycle. Closure characteristics varied significantly among the samples. The unheated granite has cracks with rough, pitted, and mismatched walls. Only partial closure occurred under stress with many sections remaining open. Crack porosity is reduced but continues to be interconnected. Fractures in the preheated granite and diabase are also irregular, but the walls are well-matched and closure is nearly complete. The cracks in the heated granite closed at lower stresses than in the diabase. As the maximum stress was approached for the heated granite, new transgranular cracks formed and preexisting cracks were enlarged. The variations in closure rate and character were also observed in strain measurements.

  1. Method for observing phase objects without halos and directional shadows

    NASA Astrophysics Data System (ADS)

    Suzuki, Yoshimasa; Kajitani, Kazuo; Ohde, Hisashi

    2015-03-01

    A new microscopy method for observing phase objects without halos and directional shadows is proposed. The key optical element is an annular aperture at the front focal plane of a condenser with a larger diameter than those used in standard phase contrast microscopy. The light flux passing through the annular aperture is changed by the specimen's surface profile and then passes through an objective and contributes to image formation. This paper presents essential conditions for realizing the method. In this paper, images of colonies formed by induced pluripotent stem (iPS) cells using this method are compared with the conventional phase contrast method and the bright-field method when the NA of the illumination is small to identify differences among these techniques. The outlines of the iPS cells are clearly visible with this method, whereas they are not clearly visible due to halos when using the phase contrast method or due to weak contrast when using the bright-field method. Other images using this method are also presented to demonstrate a capacity of this method: a mouse ovum and superimposition of several different images of mouse iPS cells.

  2. Direct observation of optical excitation transfer based on resonant optical near-field interaction

    NASA Astrophysics Data System (ADS)

    Nomura, W.; Yatsui, T.; Kawazoe, T.; Naruse, M.; Runge, E.; Lienau, C.; Ohtsu, M.

    2012-05-01

    This article reports the direct observation of long-distance optical excitation transfer based on resonant optical near-field interactions in randomly distributed quantum dots (QDs). We fabricated optical excitation transfer paths based on randomly distributed QDs by using CdSe/ZnS core-shell QDs and succeeded for the first time in obtaining output signals resulting from a unidirectional optical excitation transfer length of 2.4 ?m. Furthermore, we demonstrate that the optical excitation transfer occurs via the resonant excited levels of the QDs with a comparative experiment using non-resonant QDs. This excitation-transfer mechanism allows for intersecting, non-interacting nano-optical wires.

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

    NASA Astrophysics Data System (ADS)

    Petrosian, Vahé; Chen, Qingrong

    2014-05-01

    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.

  4. Direct Observations Of Microbial Activity At Extreme Pressures

    NASA Astrophysics Data System (ADS)

    Sharma, A.; Scott, J. H.; Cody, G. D.; Fogel, M.; Hazen, R. M.; Hemley, R. J.; Huntress, W. T.

    2002-12-01

    Microbial communities adapt to a wide range of pressures, temperatures, salinities, pH, and oxidation states. Although, significant attention has been focused on the effects of high and low temperature on physiology, there is some evidence that elevated pressure may also manifest interesting effects on cellular physiology, such as enzyme inactivation, cell-membrane breach, and suppression of protein interactions with various substrates. However, exactly how these factors affect intact cells is not well understood. In this study, we have adapted diamond anvil cells to explore the effects of high pressure on microbial life. We used the rate of microbial formate oxidation as a probe of metabolic viability. The utilization of formate by microorganisms is a fundamental metabolic process in anaerobic environments. We monitored in-situ microbial formate oxidation via molecular spectroscopy for Shewanella oneidensis strain MR1 and Escherichia coli strain MG1655 at high pressures (68 to 1060 MPa). At pressures of 1200 to 1600 MPa, living bacteria resided in fluid inclusions in ice-VI crystals and continued to be viable upon subsequent release to ambient pressures (0.1 MPa). Furthermore, direct microscopic observations indicate that these cells maintain their ability for cellular division upon decompression from such high pressures. Evidence of microbial viability and activity at these extreme pressures expands by an order of magnitude the range of conditions representing the habitable zone in the solar system. These results imply that pressure may not be a significant impediment to life. The maximum pressure explored in this work is equivalent to a depth of ~ 50 km below Earth's crust, or ~ 160 km in a hypothetical ocean. The pressures encountered at the depths of thick ice caps and deep crustal subsurface may not be a limiting factor for the existence of life. This suggests that deep (water/ice) layers of Europa, Callisto, or Ganymede, subduction zones on Earth, and the polar ice caps of Mars might provide viable settings for life unhindered by the high pressures.

  5. Cryogenic Transmission Electron Microscopy for Direct Observation of Polymer and Small-Molecule Materials and Structures in Solution

    Microsoft Academic Search

    Sheng Zhong; Darrin J. Pochan

    2010-01-01

    The application of cryogenic transmission electron microscopy (cryo-TEM) in the study of molecular self-assembly of amphiphilic macromolecules, lipid\\/surfactants, peptides, and other hybrid material systems is quickly growing in popularity as a standard characterization technique. Cryo-TEM allows the direct visualization of nanostructures and microstructures embedded in a thin film of vitrified solvent at liquid nitrogen temperature. This direct observation technique provides

  6. A simple hardware model for the direct observation of voltage-clamp performance under realistic conditions.

    PubMed

    Draguhn, A; Pfeiffer, M; Heinemann, U; Polder, R

    1997-12-30

    A new hardware cell model for electrophysiological recording has been constructed which allows for the assessment of voltage clamp accuracy in different recording situations. Each compartment consists of a capacitor in parallel with a variable resistor and can be connected to other compartments by a variable axial resistance. The simulated membrane resistance can be changed extrinsically by a command voltage input which is optically coupled to the cell without any direct galvanic contact. Each compartment possesses a buffer amplifier which reads out the potential at the simulated membrane element, (e.g. 'somatic' or 'dendritic' potential). The model allows for the direct observation of typical situations and problems arising in electrophysiological experiments. We used the model to monitor deviations between the 'intracellular' and the command voltage, e.g. due to series resistance errors. We also used the model to simulate synaptic currents which were generated by triangular membrane conductance changes. The results demonstrate the strong influence of synaptic location and series resistance on voltage clamp fidelity. The cell model is a new and easy-to-handle tool for the observation of voltage control under realistic experimental conditions. PMID:9497006

  7. Advanced chemistry-transport modeling and observing systems allow daily air quality observations, short-term forecasts, and real-time analyses of air quality at the global and

    E-print Network

    Paris-Sud XI, Université de

    Advanced chemistry-transport modeling and observing systems allow daily air quality observations, short-term forecasts, and real-time analyses of air quality at the global and European scales control measures that could be taken for managing such episodes, European-scale air quality forecasting

  8. Microwave observations of Saturn's rings: anisotropy in directly transmitted and scattered saturnian thermal emission

    NASA Astrophysics Data System (ADS)

    Dunn, David E.; Molnar, Lawrence A.; Niehof, Jon T.; de Pater, Imke; Lissauer, Jack J.

    2004-09-01

    We present a new Very Large Array (VLA) image of Saturn, made from data taken in October 1998 at a wavelength of ?3.6 cm. The moderate ring opening angle ( B?15°) allows us to explore direct transmission of microwave photons through the A and C rings. We find a strong asymmetry of photons transmitted through the A ring, but not in the C ring, a new diagnostic of wake structure in the ring particles. We also find a weak asymmetry between east and west for the far side of the ansae. To facilitate quantitative comparison between dynamic models of the A ring and radio observations, we extend our Monte Carlo radiative transfer code (described in Dunn et al., 2002, Icarus 160, 132-160) to include idealized wakes. We show the idealized model can reproduce the properties of dynamic simulations in directly transmitted light. We examine the model behavior in directly transmitted and scattered light over a range of physical and geometric wake parameters. Finally, we present a wake model with a plausible set of physical parameters that quantitatively reproduces the observed intensity and asymmetry of the A ring both across the planet and in the ansae.

  9. A direct way to observe absolute molecular handedness

    NASA Astrophysics Data System (ADS)

    Vager, Zeev

    2014-07-01

    We claim that the polarization of electrons tunneling through the molecular electric dipole direction uniquely determines the handedness of chiral centers. Unique labeling of chiral stereo-centers must include their handedness. The conventional method is formally known as the R, S nomenclature or the Ingold-Prelog priority (CIP) rules. It requires knowledge of the spatial absolute configuration of that center. Traditionally, experimental methods of extracting handedness go through the absolute configuration and only then would the CIP convention be applied. Here we show that a direct experimental method of determination of the natural molecular handedness by the polarization of tunneling electrons is almost always compatible with the CIP convention. By the sole use of symmetry arguments we show that the chiral molecular symmetry eliminates the need of fine structure splitting. As a consequence, the polarization of electrons tunneling through the molecular electric dipole direction uniquely determines their handedness.

  10. A new pressure jump cell for direct microscopic observations

    Microsoft Academic Search

    J. Wenzel; G. M. Schneider

    1981-01-01

    A pressure jump autoclave for direct microscopic investigations is described. In the instrument, the pressure jump principle with rupture diaphragm is realized in a simple manner by use of Swagelok standard parts, which may easily be adapted to other types of autoclaves. Up to now the cell has been used for the investigation of aging processes in liquid–liquid precipitates, but

  11. Photometric and CCD direct image observation of comet Encke

    NASA Technical Reports Server (NTRS)

    Mccrosky, R. E.

    1981-01-01

    Attempted detection of periodic variations in brightness of the comet Encke is described. Viewing problems due to the position, faintness, and rate of motion of the comet are discussed. The failure of attempts to perform photoelectric photometry and CCD imaging is described. Photometric observations of the prototype Earth crosser, (1862) Apollo, are described and a photoelectric light curve of observations made during a four-hour period is presented.

  12. First direct observation of Dirac fermions in graphite

    Microsoft Academic Search

    S. Y. Zhou; G.-H. Gweon; J. Graf; A. V. Fedorov; C. D. Spataru; R. D. Diehl; Y. Kopelevich; D.-H. Lee; Steven G. Louie; A. Lanzara

    2006-01-01

    Originating from relativistic quantum field theory, Dirac fermions have been invoked recently to explain various peculiar phenomena in condensed-matter physics, including the novel quantum Hall effect in graphene, the magnetic-field-driven metal-insulator-like transition in graphite, superfluidity in 3He (ref. 5) and the exotic pseudogap phase of high-temperature superconductors. Despite their proposed key role in those systems, direct experimental evidence of Dirac

  13. A new pressure jump cell for direct microscopic observations

    NASA Astrophysics Data System (ADS)

    Wenzel, J.; Schneider, G. M.

    1981-12-01

    A pressure jump autoclave for direct microscopic investigations is described. In the instrument, the pressure jump principle with rupture diaphragm is realized in a simple manner by use of Swagelok standard parts, which may easily be adapted to other types of autoclaves. Up to now the cell has been used for the investigation of aging processes in liquid-liquid precipitates, but the instrument can also be suited for other purposes.

  14. Incoherent scatter radar directional pattern using radio astronomical observations

    NASA Astrophysics Data System (ADS)

    Medvedev, A. V.; Zavorin, A. V.; Lebedev, V. P.; Lubyshev, B. I.; Nosov, V. E.

    2002-03-01

    The Irkutsk Incoherent Scatter (IS) radar is a unique facility in Russia, designed for geophysical and radio- probing investigations of the upper atmosphere. The range of problems tackled using the radar is quite extensive. Having a high potential and investigative capability, the radar represents an extremely sophisticated engineering facility. A maximum possible knowledge of all performance data of this instrument is necessary for conducting accurate measurements of space environment parameters and for scientific experiments. Of particular interest in this regard is the radar's antenna system. The spatial distribution of the radiation power (directional pattern) of the antenna system is as yet imperfectly understood. Because of the complexity and the unconventional nature of the antenna design, a mathematical simulation and calculation of the directional pattern involves a highly cumbersome task, and the reliability of such calculations is low. The overall worldwide practice shows that the most powerful tool for obtaining the directional pattern characteristics is to measure the variations of the noise power level when various cosmic radio sources traverse the beam. The advancement of digital technology in the present state of the art makes it possible to record large amounts of information needed to construct an accurate spatial distribution of the power received and radiated by the antenna. Results, thus obtained, are useful for correctly selecting the IS radar operation modes.

  15. Dynamic control of directional asymmetry observed in ultrafast laser direct writing

    NASA Astrophysics Data System (ADS)

    Salter, P. S.; Booth, M. J.

    2012-10-01

    A liquid crystal spatial light modulator (SLM) is used to control the focal symmetry and the associated directional "quill" effect encountered when using a femtosecond laser for direct laser writing of fused silica. Applying a blazed grating to the SLM effectively introduces pulse front tilt to the fabrication beam and a spatiotemporal asymmetry at the focus. As a result different fabricated features are generated when moving the substrate in opposite directions relative to the tilt. It is additionally shown that inhomogeneous pupil illumination can cause similar directionality in the fabrication via a spatial asymmetry in the focus.

  16. Observations of directional gamma prime coarsening during engine operation

    NASA Technical Reports Server (NTRS)

    Draper, Susan L.; Hull, David R.; Dreshfield, Robert L.

    1987-01-01

    Two alloys with negative mismatch parameters, NASAIR 100 and a modified NASAIR 100 called Alloy 3 were run as turbine blades in an experimental ground based Garret TFE731 engine for up to 200 hr. The directional coarsening of gamma prime (rafting) that developed during engine testing was analyzed and compared to previous research from laboratory tests. The blades were found to be rafted normal to the centrifugal stress axis over much of the span, but near the surfaces, the blades were found to be rafted parallel to the centrifugal stress axis for certain cycles. Representative photomicrographs of the blades and the effects of stress and temperature on raft formation are shown.

  17. Direct observations of atomic diffusion by scanning transmission electron microscopy

    PubMed Central

    Isaacson, M.; Kopf, D.; Utlaut, M.; Parker, N. W.; Crewe, A. V.

    1977-01-01

    The feasibility of using a high-resolution scanning transmission electron microscope to study the diffusion of heavy atoms on thin film substrates of low atomic number has been investigated. We have shown that it is possible to visualize the diffusion of individual uranium atoms adsorbed to thin carbon film substrates and that the observed motion of the atoms does not appear to be induced by the incident electron beam. Images PMID:16592396

  18. Direct and simultaneous observation of ferroelectric and magnetic domains

    Microsoft Academic Search

    H. Z. Song; Y. X. Li; K. Y. Zhao; H. R. Zeng; S. X. Hui; G. R. Li; Q. R. Yin

    2009-01-01

    The ferroelectric\\/magnetic domain structure in a magnetoelectric binding BaTiO3\\/Fe81Ga19 and the ferroelectric\\/crystallographic domain structure in a magnetoelectric binding PMN-34PT\\/Mn50Ni28Ga22 were observed successfully by scanning electron acoustic microscopy (SEAM). Both the stripe ferroelectric domains in single crystals and the stripe magnetic domains in polycrystalline grains are obtained simultaneously, which exhibits that the scanning electron acoustic microscopy is a unique imaging technique.

  19. Direct observation of processes in a solidifying dispersion

    Microsoft Academic Search

    H. Klein; H. U. Walter; A. Bewersdorff; J. Pöttschke

    1984-01-01

    The evolution of a dispersion under the action of temperature gradients and solidification was followed optically in a transparent molten salt (CsCl) with inclusions of Pb-droplets and gas bubbles. This system is believed to model a solidifying metallic alloy. Rejection of Pb-particles by the solidification front was observed, while large gas bubbles were incorporated. Thermocapillary convection at the gas bubbles

  20. Direct and indirect inactivation of tumor cell protective catalase by salicylic acid and anthocyanidins reactivates intercellular ROS signaling and allows for synergistic effects.

    PubMed

    Scheit, Katrin; Bauer, Georg

    2015-03-01

    Salicylic acid and anthocyanidins are known as plant-derived antioxidants, but also can provoke paradoxically seeming prooxidant effects in vitro. These prooxidant effects are connected to the potential of salicylic acid and anthocyanidins to induce apoptosis selectively in tumor cells in vitro and to inhibit tumor growth in animal models. Several epidemiological studies have shown that salicylic acid and its prodrug acetylsalicylic acid are tumor-preventive for humans. The mechanism of salicylic acid- and anthocyanidin-dependent antitumor effects has remained enigmatic so far. Extracellular apoptosis-inducing reactive oxygen species signaling through the NO/peroxynitrite and the HOCl signaling pathway specifically induces apoptosis in transformed cells. Tumor cells have acquired resistance against intercellular reactive oxygen species signaling through expression of membrane-associated catalase. Here, we show that salicylic acid and anthocyanidins inactivate tumor cell protective catalase and thus reactive apoptosis-inducing intercellular reactive oxygen species signaling of tumor cells and the mitochondrial pathway of apoptosis Salicylic acid inhibits catalase directly through its potential to transform compound I of catalase into the inactive compound II. In contrast, anthocyanidins provoke a complex mechanism for catalase inactivation that is initiated by anthocyanidin-mediated inhibition of NO dioxygenase. This allows the formation of extracellular singlet oxygen through the reaction between H(2)O(2) and peroxynitrite, amplification through a caspase8-dependent step and subsequent singlet oxygen-mediated inactivation of catalase. The combination of salicylic acid and anthocyanidins allows for a remarkable synergistic effect in apoptosis induction. This effect may be potentially useful to elaborate novel therapeutic approaches and crucial for the interpretation of epidemiological results related to the antitumor effects of secondary plant compounds. PMID:25653236

  1. 10 CFR 26.115 - Collecting a urine specimen under direct observation.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...Collecting a urine specimen under direct observation. 26.115 Section 26.115 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Collecting Specimens for Testing § 26.115 Collecting a urine specimen under direct...

  2. 10 CFR 26.115 - Collecting a urine specimen under direct observation.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...Collecting a urine specimen under direct observation. 26.115 Section 26.115 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Collecting Specimens for Testing § 26.115 Collecting a urine specimen under direct...

  3. 10 CFR 26.115 - Collecting a urine specimen under direct observation.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...false Collecting a urine specimen under direct...Collecting Specimens for Testing § 26.115 Collecting a urine specimen under direct...observer shall watch the urine go from the donor's...act to subvert the testing process....

  4. Direct observation of multiple-scattering processes in pion absorption

    SciTech Connect

    Yokota, H.; Mori, T.; Katsumi, T.; Igarashi, S.; Hama, K.; Chiba, R.; Nakai, K.; Chiba, J.; En'yo, H.; Sasaki, S.; and others

    1987-01-19

    In the angular correlation of the (..pi../sup -/,pp) reaction, two rather sharp peaks were observed for /sup 6/Li and C. These peaks were considered to be associated with two-step processes; one is pp-pp scattering after the (..pi../sup -/,pn) reaction, and the other is the ..pi../sup -/p-..pi../sup 0/n reaction followed by the (..pi../sup 0/,pp) reaction. The intranuclear cascade model reproduced very well the two peaks. These results show that two-step processes are important in pion-absorption reactions for light nuclei.

  5. Direct observation of magnetic metastability in individual iron nanoparticles.

    PubMed

    Balan, Ana; Derlet, Peter M; Rodríguez, Arantxa Fraile; Bansmann, Joachim; Yanes, Rocio; Nowak, Ulrich; Kleibert, Armin; Nolting, Frithjof

    2014-03-14

    X-ray photoemission electron microscopy combined with x-ray magnetic circular dichroism is used to study the magnetic properties of individual iron nanoparticles with sizes ranging from 20 down to 8 nm. While the magnetocrystalline anisotropy of bulk iron suggests superparamagnetic behavior in this size range, ferromagnetically blocked particles are also found at all sizes. Spontaneous transitions from the blocked state to the superparamagnetic state are observed in single particles and suggest that the enhanced magnetic energy barriers in the ferromagnetic particles are due to metastable, structurally excited states with unexpected life times. PMID:24679323

  6. Direct observation of internal energy distributions of C5(-).

    PubMed

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

    2013-08-01

    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. PMID:23927261

  7. Direct observation of selective protein capturing on molecular imprinting substrates.

    PubMed

    Fukazawa, Kyoko; Li, Qiang; Seeger, Stefan; Ishihara, Kazuhiko

    2013-02-15

    A sensing interface for specific protein capture was fabricated using a novel molecular imprinting (MIP) process. Bovine serum albumin (BSA) and ovalbumin (OVA) were imprinted on a quartz substrate with modified alkyl groups, and target protein capture was detected using a deep-UV fluorescence image microscope (UVFLIM). The imprinted protein was immobilized to silica beads (diameter: 15 ?m) using a phospholipid polymer containing both active ester groups and silane coupling groups, which were used as protein stamps to prepare the imprinting surface. Protein recognition sites were constructed by integrating sodium dodecyl sulfate (SDS) as the ligand, which was immobilized with a biocompatible photoreactive phospholipid polymer. When BSA solution was added to the BSA-based MIP substrate, strong fluorescence was observed from the tryptophan residue of BSA. In contrast, for the OVA-based MIP substrate and non-MIP substrate, no fluorescence was observed. The surface showed good selectivity of BSA against OVA. The phospholipid polymer layer prevented non-specific protein adsorption, resulting in highly selective protein recognition. Further, when the protein-imprinted substrate was constructed without ligands, neither protein was captured on the substrate. We demonstrated the importance of ligand integration for capturing target proteins at specific positions. UVFLIM can be used to detect biomolecules at the single-molecule level by using intrinsic fluorescence without molecular labeling. Our new protein-imprinted surface used with UVFLIM is a versatile tool for capturing biomolecules. PMID:22784498

  8. Direct observation of ballistic Brownian motion on a single particle

    E-print Network

    Rongxin Huang; Branimir Lukic; Sylvia Jeney; Ernst-Ludwig Florin

    2010-03-09

    At fast timescales, the self-similarity of random Brownian motion is expected to break down and be replaced by ballistic motion. So far, an experimental verification of this prediction has been out of reach due to a lack of instrumentation fast and precise enough to capture this motion. With a newly developed detector, we have been able to observe the Brownian motion of a single particle in an optical trap with 75 MHz bandwidth and sub-{AA}ngstrom spatial precision. We report the first measurements of ballistic Brownian motion as well as the first determination of the velocity autocorrelation function of a Brownian particle. The data are in excellent agreement with theoretical predictions taking into account the inertia of the particle and the surrounding fluid as well as hydrodynamic memory effects.

  9. Direct Observations of an Extragalactic Advection Dominated Accretion Flow

    NASA Astrophysics Data System (ADS)

    Hogan, M.; Edge, A.; Salome, P.; Combes, F.; Russell, H.; McNamara, B.; Grainge, K.; Lim, J.

    2015-07-01

    We report the detection of central, unresolved continuum emission in NGC5044 that is likely emerging from an Advection Dominated Accretion Flow (ADAF). ADAFs are thought to power Radio-Mode feedback in galaxies and clusters, yet in super-massive black holes they are difficult to unambiguously detect against emission from other sources, such as dust and jets. Only the ADAF in Sgr-A* has previously been compellingly detected. A surprisingly bright, 50mJy continuum source at 235 GHz was found in a Cycle-0 ALMA CO(2-1) observation of NGC5044. Having obtained multi-wavelength follow-up, we find that the shape of the mm-continuum and the narrow, 5-10 km s^{-1} width of the CO(2-1) absorption line are consistent with emission from a very compact central continuum source. Its continuum properties and energetics are consistent with self-absorbed synchrotron emission from an ADAF. Intriguingly, the spectral component associated with the ADAF is apparently varying by ˜20% on short (<1 month) timescales, implying that the accretion rate onto the AGN varies similarly. We will discuss the possibility that ADAFs in massive galaxies are fuelled by molecular gas, which has been recently discovered in NGC5044 and other systems.

  10. Direct observations of the atmospheric processing of Asian mineral dust

    NASA Astrophysics Data System (ADS)

    Sullivan, R. C.; Guazzotti, S. A.; Sodeman, D. A.; Prather, K. A.

    2007-02-01

    The accumulation of secondary acids and ammonium on individual mineral dust particles during ACE-Asia has been measured with an online single-particle mass spectrometer, the ATOFMS. Changes in the amounts of sulphate, nitrate, and chloride mixed with dust particles correlate with air masses from different source regions. The uptake of secondary acids depended on the individual dust particle mineralogy; high amounts of nitrate accumulated on calcium-rich dust while high amounts of sulphate accumulated on aluminosilicate-rich dust. Oxidation of S(IV) to S(VI) by iron in the aluminosilicate dust is a possible explanation for this enrichment of sulphate, which has important consequences for the fertilization of remote oceans by soluble iron. This study shows the segregation of sulphate from nitrate and chloride in individual aged dust particles for the first time. A transport and aging timeline provides an explanation for the observed segregation. Our data suggests that sulphate became mixed with the dust first. This implies that the transport pathway is more important than the reaction kinetics in determining which species accumulate on mineral dust. Early in the study, dust particles in volcanically influenced air masses were mixed predominately with sulphate. Dust mixed with chloride then dominated over sulphate and nitrate when a major dust front reached the R. V. Ronald Brown. We hypothesize that the rapid increase in chloride on dust was due to mixing with HCl(g) released from acidified sea salt particles induced by heterogeneous reaction with volcanic SO2(g), prior to the arrival of the dust front. The amount of ammonium mixed with dust correlated strongly with the total amount of secondary acid reaction products in the dust. Submicron dust and ammonium sulphate were internally mixed, contrary to frequent reports that they exist as external mixtures. The size distribution of the mixing state of dust with these secondary species validates previous mechanisms of the atmospheric processing of dust and generally agrees with simulated aerosol chemistry from the STEM-2K3 model. This series of novel results has important implications for improving the treatment of dust in global chemistry models and highlights a number of key processes that merit further investigation through laboratory and field studies.

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

    PubMed Central

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

    2013-01-01

    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. PMID:24282244

  12. First direct observation of self-imaging effect in active multimode-interference semiconductor laser diodes

    Microsoft Academic Search

    Syogo Shimizu; Mohd Dannial Bin Razali; Kenichi Kasahara; Kiichi Hamamoto; Masaki Ohya

    2006-01-01

    We report the first direct observation of the self-imaging effect in active multimode-interference semiconductor laser diodes (MMI-SLDs). Interference patterns inside laser diode waveguides were obtained by using the electroluminescence (EL) method. To the best of our knowledge, this result is the first direct observation of the self-imaging effect in self-photon-emitting active waveguides such as laser diodes. The observed EL pattern

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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.

  14. Direct observation of Rydberg-Rydberg transitions via CPmmW spectroscopy

    E-print Network

    Zhou, Yan, Ph. D. Massachusetts Institute of Technology

    2014-01-01

    Rydberg-Rydberg transitions of BaF molecules have been directly observed in our lab. The key to the experimental success is our ability to combine two powerful and new technologies, Chirped-Pulse millimeter-Wave spectroscopy ...

  15. Direct Retrieval of Line-of-Sight Atmospheric Structure From Limb Sounding Observations

    NASA Technical Reports Server (NTRS)

    Livesey, N.; Read, W.

    1999-01-01

    Optimal estimation of atmospheric temperature and composition from limb sounding observations is extended to the direct retrieval of line-of-sight atmospheric structure that can be obtained in certain limb viewing geometries.

  16. Direct observations and analysis of the spallation of alumina scales grown on PM2000 alloy

    Microsoft Academic Search

    P. Lours; J. Sniezewski; Y. Le Maoult; B. Pieraggi

    2008-01-01

    The spallation during cooling or thermal cycling of alumina scales grown at high temperature on PM2000 alloy is directly observed and recorded using CCD cameras. This simple and direct method permits to determine easily and accurately the scale spallation kinetics. In addition, it provides many insights on the spallation mechanisms and processes and their evolution as well as on the

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

    ERIC Educational Resources Information Center

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

    2010-01-01

    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…

  18. Direct assessment of groundwater vulnerability from single observations of multiple contaminants

    Microsoft Academic Search

    Fred Worrall; Dana W. Kolpin

    2003-01-01

    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

  19. Trajectory Sampling for Direct Traffic Observation N. G. Duffield M. Grossglauser

    E-print Network

    Grossglauser, Matthias

    ­term traffic engi­ neering. Traffic control operates on a time­scale of seconds and without direct human1 Trajectory Sampling for Direct Traffic Observation N. G. Duffield M. Grossglauser AT&T Labs ­ Research 180 Park Ave, Florham Park NJ 07932, USA fduffield, mgrossg@research.att.com Abstract--- Traffic

  20. 2.3 Terrestrial Ecology Observing Systems (TEOS) Our goal for the TEOS program was to develop a dense network of sensors that would allow us to track the spatial

    E-print Network

    California at Los Angeles, University of

    the disturbances provide opportunities for invasive species), or by minirhizotron observations that scale to roots be directed remotely, and frequently. Our automated minirhizotron (AMR) has the resolution to observe fine

  1. Direct observation of roaming radicals in the thermal decomposition of acetaldehyde.

    SciTech Connect

    Sivaramakrishnan, R.; Michael, J. V.; Klippenstein, S. J.; Chemical Sciences and Engineering Division

    2010-01-21

    The thermal dissociation of acetaldehyde has been studied with the reflected shock tube technique using H(D)-atom atomic resonance absorption spectrometry detection. The use of an unreversed light source yields extraordinarily sensitive H atom detection. As a result, we are able to measure both the total decomposition rate and the branching to radical versus molecular channels. This branching provides a direct measure of the contribution from the roaming radical mechanism since the contributions from the usual tight transition states are predicted by theory to be negligible. The experimental observations also provide a measure of the rate coefficient for H + CH{sub 3}CHO. Another set of experiments employing C{sub 2}H{sub 5}I as an H-atom source provides additional data for this rate coefficient that extends to lower temperature. An evaluation of the available experimental results for H + CH{sub 3}CHO can be expressed by a three-parameter Arrhenius expression as k = 7.66 x 10{sup -20}T{sup 2.75} exp((-486 K)/T) cm{sup 3} molecule{sup -1} s{sup -1} (298-1415 K). Analogous experiments employing C{sub 2}D{sub 5}I as a D-atom source allow for the study of the isotopically substituted reaction. The present experiments are the only direct measure for this reaction rate constant, and the results can be expressed by an Arrhenius expression as k = 5.20 x 10{sup -10} exp((-4430 K)/T) cm{sup 3} molecule{sup -1} s{sup -1} (1151-1354 K). The H/D + CH{sub 3}CHO reactions are also studied with ab initio transition-state theory, and the results are in remarkably good agreement with the current experimental data.

  2. The art major at Stetson is designed to allow students to develop their personal styles and directions on the base of a strong foundation

    E-print Network

    Miles, Will

    Art The art major at Stetson is designed to allow students to develop their personal styles and contemporary artistic theories. Because this process takes place in the context of a liberal arts college to work outside of class. The studio art program at Stetson has particular strengths in painting, drawing

  3. Direct observation of fine structure in ion tracks in amorphous Si3N4 by TEM

    NASA Astrophysics Data System (ADS)

    Nakajima, K.; Morita, Y.; Suzuki, M.; Narumi, K.; Saitoh, Y.; Ishikawa, N.; Hojou, K.; Tsujimoto, M.; Isoda, S.; Kimura, K.

    2012-11-01

    Thin films of amorphous Si3N4 (thickness 20 nm) were irradiated with 120-720 keV C60+,2+ ions and observed using transmission electron microscopy (TEM). The ion track produced in an amorphous material was directly observed by TEM. For quantitative analysis, the ion tracks were also observed using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). The observed ion track consists of a low density core (radius ˜2.5 nm) and a high density shell (width ˜2.5 nm), which is very similar to the ion tracks in amorphous SiO2 irradiated with high energy heavy ions observed by small angle X-ray scattering (SAXS). Although the observed ion tracks may be affected by surface effects, the present result indicates that TEM and HAADF-STEM have potential to observe directly the fine structures of ion tracks in amorphous materials.

  4. Journal of Membrane Science xxx (2004) xxxxxx Direct observation of biofouling in cross-flow microfiltration

    E-print Network

    2004-01-01

    Journal of Membrane Science xxx (2004) xxx­xxx Direct observation of biofouling in cross-flow observation of microbial cell deposition and release in cross-flow microfiltration. Initial deposition rates with small increases to membrane and particle zeta potential. Cross-flow velocity had no effect on initial

  5. Direct observation of asymmetric domain wall motion in a ferroelectric capacitor

    E-print Network

    Chen, Long-Qing

    Direct observation of asymmetric domain wall motion in a ferroelectric capacitor Ja Kyung Lee a,1 observations of the 180° polarization switching process of a PbZr0.2Ti0.8O3 (PZT) capacitor. The preferential capacitors, switching between two bistable polarization states that are related by a 180° rotation

  6. Direct Observation of Sub-Poissonian Number Statistics in a Degenerate Bose Gas

    NASA Astrophysics Data System (ADS)

    Chuu, C.-S.; Schreck, F.; Meyrath, T. P.; Hanssen, J. L.; Price, G. N.; Raizen, M. G.

    2005-12-01

    We report the direct observation of sub-Poissonian number fluctuation for a degenerate Bose gas confined in an optical trap. Reduction of number fluctuations below the Poissonian limit is observed for average numbers that range from 300 to 60 atoms.

  7. Direct Observations of the Composition of Sub20 Nanometer Ambient Aerosol

    Microsoft Academic Search

    K. F. Moore; J. N. Smith; F. L. Eisele; P. H. McMurry

    2002-01-01

    Understanding new particle formation in the atmosphere depends upon many factors including detailed knowledge of their chemical composition. The chemical composition of sub-20 nanometer ambient aerosol particles, however, is typically inferred from observations of the aerosol behavior when subjected to varying conditions during sampling. Direct observations of aerosol chemical composition are usually limited to or dominated by larger particles of

  8. Anodal transcranial direct current stimulation over premotor cortex facilitates observational learning of a motor sequence.

    PubMed

    Wade, Stephanie; Hammond, Geoff

    2015-06-01

    Motor skills, including complex movement sequences, can be acquired by observing a model without physical practice of the skill, a phenomenon known as observational learning. Observational learning of motor skills engages the same memory substrate as physical practice, and is thought to be mediated by the action observation network, a bilateral fronto-parietal circuit with mirror-like properties. We examined the effects of anodal transcranial direct current stimulation (tDCS) over premotor cortex, a key node of the action observation network, on observational learning of a serial response time task. Results showed that anodal tDCS during observation of the to-be-learned sequence facilitated reaction times in the subsequent behavioral test. The study provides evidence that increasing excitability of the action observation network during observation can facilitate later motor skill acquisition. PMID:25865458

  9. Unimolecular thermal decomposition of phenol and d5-phenol: Direct observation of cyclopentadiene formation via cyclohexadienone

    NASA Astrophysics Data System (ADS)

    Scheer, Adam M.; Mukarakate, Calvin; Robichaud, David J.; Nimlos, Mark R.; Carstensen, Hans-Heinrich; Barney Ellison, G.

    2012-01-01

    The pyrolyses of phenol and d5-phenol (C6H5OH and C6D5OH) have been studied using a high temperature, microtubular (?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 ?tubular reactor of approximately 50-100 ?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; C6H5OH ? c-C6H6 = O ? c-C5H6 + CO. The cyclopentadiene loses a H atom to generate the cyclopentadienyl radical which further decomposes to acetylene and propargyl radical; c-C5H6 ? c-C5H5 + H ? HC?CH + HCCCH2. 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; C6H5O-H ? C6H5O + H ? c-C5H5 + CO. The direct decarbonylation reaction remains an important channel in the thermal decomposition mechanisms of the dihydroxybenzenes. Both catechol (o-HO-C6H4-OH) and hydroquinone (p-HO-C6H4-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.

  10. Direct Observation of Multiple Tautomers of Oxythiamine and their Recognition by the Thiamine Pyrophosphate Riboswitch

    PubMed Central

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

    2014-01-01

    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 non-phosphorylated form, oxythiamine (OxyT). OxyTPP, like 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

  11. Vertical structure and transport of the Antarctic Circumpolar Current in Drake Passage from direct velocity observations

    Microsoft Academic Search

    Yvonne L. Firing; Teresa K. Chereskin; Matthew R. Mazloff

    2011-01-01

    The structure of the Antarctic Circumpolar Current (ACC) in Drake Passage is examined using 4.5 years of shipboard acoustic Doppler current profiler (ADCP) velocity data. The extended 1000 m depth range available from the 38 kHz ADCP allows us to investigate the vertical structure of the current. The mean observed current varies slowly with depth, while eddy kinetic energy and

  12. Direct observation of molecularly-aligned molecules in the second physisorbed layer-CO/Ag(110)

    SciTech Connect

    Lee, J.-G. (Chevron Science Center, Pittsburgh, PA); Hong, S.-H. (Chevron Science Center, Pittsburgh, PA); Ahner, J. (Chevron Science Center, Pittsburgh, PA); Zhao, X. (Univ. of Pittsburgh, PA); Chen, L.; Johnson, J.K.; Yates, J.T., Jr. (Chevron Science Center, Pittsburgh, PA)

    2006-01-25

    We report the direct observation of oriented second-layer physisorbed molecules on a single crystal surface by electron stimulated desorption. Experiments and simulations show that the orientation of the second-layer physisorbed CO molecules on Ag(110) is the result of both electrostatic and dispersion forces from the underlying chemisorbed CO and Ag atoms. At 25 K, the physisorbed C-O bond is tilted and azimuthally oriented with the C-O bond axis inclined in an azimuthal plane at 45° to the principal Ag( 110) azimuthal crystallographic directions. The O atom in CO is directed outward, giving an O+ beam at 43° to the normal.

  13. Estimating nonlinear mixing effects for arid vegetation scenes with MISR channels and observation directions

    SciTech Connect

    Villeneuve, P.V.; Gerstl, S.A. [Los Alamos National Lab., NM (United States); Asner, G.P. [Univ. of Colorado, Boulder, CO (United States)

    1998-12-01

    A Monte-Carlo ray-trace model has been applied to simulated sparse vegetation desert canopies in an effort to quantify the spectral mixing (both linear and nonlinear) occurring as a result of radiative interactions between vegetation and soil. This work is of interest as NASA is preparing to launch new instruments such as MISR and MODIS. MISR will observe each ground pixel from nine different directions in three visible channels and one near-infrared channel. It is desired to study angular variations in spectral mixing by quantifying the amount of nonlinear spectral mixing occurring in the MISR observing directions.

  14. Expression of fluorescent proteins within the repeat long region of the Marek's disease virus genome allows direct identification of infected cells while retaining full pathogenicity.

    PubMed

    Jarosinski, Keith W; Donovan, Kathleen M; Du, Guixin

    2015-04-01

    Marek's disease virus (MDV) is a lymphotropic alphaherpesvirus and causes Marek's disease (MD) in chickens. RLORF4 is an MDV-specific gene located in the repeat long (RL) regions of the genome and is directly involved in attenuation. In this report, we generated recombinant (r)MDVs in which eGFP or mRFP was inserted in-frame of the 3' end of the RLORF4 gene. In vitro growth was unaffected and infected cells could be identified by using fluorescent microscopy. Interestingly, though inserted in-frame with RLORF4, eGFP and mRFP were expressed alone, confirming mRNA expression and splicing within the RL of MDV is complex. In vivo, rMDVs expressing mRFP or eGFP caused tumors similar to wild-type MDV. Fluorescent protein expression could be seen in spleen, tumor, and feather follicle epithelial cells. These results show that expression of fluorescent proteins within the RL region results in fluorescent rMDVs that still maintains full pathogenicity in the chicken. PMID:25725150

  15. An Adaptive Sliding Stator Flux Observer for a Direct-Torque-Controlled IPM Synchronous Motor Drive

    Microsoft Academic Search

    Zhuang Xu; M. F. Rahman

    2007-01-01

    This paper focuses on performance improvements of the stator flux estimation for a direct-torque-controlled interior permanent magnet synchronous motor drive. In this paper, an adaptive sliding observer is presented to estimate the stator flux linkage based on the motor current model. The experimental results show that the proposed observer has been able to deliver more accurate estimation than an open-loop

  16. Observer-Based Direct Adaptive Fuzzy-Neural Control for Anti-lock Braking Systems

    Microsoft Academic Search

    Guan-Ming Chen; Wei-Yen Wang; Tsu-Tian Lee; C. W. Tao

    2006-01-01

    In this paper, an observer-based direct adaptive fuzzy-neural controller (ODAFNC) for an anti-lock braking system (ABS) is developed under the con- straint that only the system output, i.e., the wheel slip ratio, is measurable. The main control strategy is to force the wheel slip ratio to well track the optimal value, which may vary with the environment. The observer-based output

  17. RECYCLING PROGRAM TYPE LOCATION ALLOWED NOT ALLOWED

    E-print Network

    Miami, University of

    RECYCLING PROGRAM TYPE LOCATION ALLOWED NOT ALLOWED Batteries, toner, ink cartridges & cell phones and recycling is an important part of that effort. Below is a guide to on-campus recycling at RSMAS: Visit http://www.rsmas.miami.edu/msgso/ for map of recycling bin locations. NOTE: This is not an exhaustive list. If unauthorized items are found

  18. When one person observes another making a sandwich or chang-ing a flat tire, knowledge about the parts of the activity can allow

    E-print Network

    of fine-grain segments7. In short, human observers know about the parts of everyday activities, use to school or to a birthday party2, and adults use knowledge of event struc- ture in reading, remembering, we measured local brain activity with functional magnetic resonance imaging (fMRI) while participants

  19. An analysis of the soil moisture-rainfall feedback, based on direct observations from Illinois

    Microsoft Academic Search

    Kirsten L. Findell; Elfatih A. B. Eltahir

    1997-01-01

    Many global and regional climate modeling studies have demonstrated the importance of the initial soil water condition in their simulations of regional rainfall distribution. However, none of these modeling studies has been tested against directly observed data. This study tests the hypothesis that soil saturation is positively correlated with subsequent precipitation by analyzing a 14-year soil moisture data set from

  20. Parallel electric fields in the upward current region of the aurora: Indirect and direct observations

    E-print Network

    California at Berkeley, University of

    Parallel electric fields in the upward current region of the aurora: Indirect and direct current region of the aurora focusing on the structure of electric fields at the boundary between account of the electric fields in the upward current region of the aurora as observed by the Fast Auroral

  1. Direct observation of initial microbial deposition onto reverse osmosis and nanofiltration membranes

    Microsoft Academic Search

    Arun Subramani; Eric M. V. Hoek

    2008-01-01

    Physicochemical factors governing initial rates of microbial deposition onto reverse osmosis (RO) and nanofiltration (NF) membranes were studied using direct microscopic observation. Deposition rates for three different microorganisms onto four NF\\/RO membranes increased with (a) increasing permeate velocity, (b) decreasing crossflow velocity, (c) increasing salt rejection, (d) increasing cell size, (e) increasing membrane surface roughness, (f) decreasing (cell-membrane) free energy

  2. Energy distribution of produced particles in multiple particle production based on data of direct observation

    Microsoft Academic Search

    A. Ohsawa; E. H. Shibuya; M. Tamada

    2001-01-01

    The energy distribution of produced particles in multiple particle production is formulated empirically based on the data of direct observations by accelerator and cosmicray experiments at 1012 ˜ 1014 eV. The formulated distribution indicates violation of the Feynman scaling law, which was shown to be valid in low energy region of = 1015 eV by extrapolation. The distribution is also

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

    ERIC Educational Resources Information Center

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

    2011-01-01

    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…

  4. Direct in Situ Observation of Synergism between Cellulolytic Enzymes during the Biodegradation of Crystalline Cellulose Fibers

    E-print Network

    Dutcher, John

    Direct in Situ Observation of Synergism between Cellulolytic Enzymes during the Biodegradation types of T. reesei cellulolytic enzymes TrCel6A, TrCel7A, and TrCel7Band their mixtures. TrCel6A and Tr. When acting alone on native cellulose fibers, each of the three enzymes is incapable of significant

  5. Disturbance observer and feedforward design for a high-speed direct-drive positioning table

    Microsoft Academic Search

    Carl J. Kempf; Seiichi Kobayashi

    1999-01-01

    Design and implementation of a discrete-time tracking controller for a precision positioning table actuated by direct-drive motors is considered. The table has acceleration capabilities in excess of 5 G, positioning accuracy at the micron level, and is used in applications such as semiconductor packaging. The controller proposed uses a disturbance observer and proportional derivative (PD) compensation in the feedback path

  6. Direct Observation in Special Education Classrooms: Concurrent Use of Two Instruments and Their Validation.

    ERIC Educational Resources Information Center

    Tindal, Gerald; Parker, Richard

    1987-01-01

    Concurrent use of two direct observation instruments (momentary time sample of task engagement and event recording of discrete student responses) were evaluated in six middle school resource rooms using either of two reading programs. Findings tended to be program specific with differences lost or diluted when data were combined across programs.…

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

    ERIC Educational Resources Information Center

    Welsh, Deborah P.; Shulman, Shmuel

    2008-01-01

    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…

  8. Three-Item Direct Observation Screen (TIDOS) for Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Oner, Pinar; Oner, Ozgur; Munir, Kerim

    2014-01-01

    We compared ratings on the Three-Item Direct Observation Screen test for autism spectrum disorders completed by pediatric residents with the Social Communication Questionnaire parent reports as an augmentative tool for improving autism spectrum disorder screening performance. We examined three groups of children (18-60 months) comparable in age…

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

    Microsoft Academic Search

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

    2009-01-01

    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

  10. Direct Observation of Nondiffusive Motion of a Brownian Particle B. Lukic,1

    E-print Network

    Weeks, Eric R.

    the environment can be gained by analyzing the particle's trajectory. For instance, single particle rheologyDirect Observation of Nondiffusive Motion of a Brownian Particle B. Lukic´,1 S. Jeney,1 C. Tischer motion of its constituents to fulfill complex functions. A Brownian particle will rapidly explore

  11. Direct observation of biofouling in cross-flow microfiltration: mechanisms of deposition and release

    Microsoft Academic Search

    Seok-Tae Kang; Arun Subramani; Eric M. V. Hoek; Marc A. Deshusses; Mark R. Matsumoto

    2004-01-01

    A laboratory-scale membrane filtration cell was constructed to enable direct microscopic observation of microbial cell deposition and release in cross-flow microfiltration. Initial deposition rates determined from microscopic images were interpreted through an interaction force model. Experimentally derived deposition rates and model calculations confirmed that initial cell and particle deposition was governed by permeation drag and electrostatic double layer forces. Microbial

  12. Standardizing the Pre-Licensure Supervision Process: A Commentary on Advocating for Direct Observation of Skills

    ERIC Educational Resources Information Center

    Gray, Neal D.; Erickson, Paul

    2013-01-01

    The present paper advocates for standardized regulations and laws for supervision of pre-licensed counselors in the United States, particularly for direct observation of clinical skills. A review of regulations by the American Counseling Association (ACA) Office of Professional Affairs (2012) reveals that only two states (Arizona and North…

  13. Female lemon sharks return to their birth waters to deliver offspring --the first direct observation

    E-print Network

    Cai, Long

    Female lemon sharks return to their birth waters to deliver offspring -- the first direct observation of such behaviour in any shark species. Kevin Feldheim at the Field Museum in Chicago, Illinois, and his colleagues collected and analysed DNA from lemon sharks (Negaprion brevirostris; pictured

  14. Direct Observation of Protein Folding, Aggregation, and a Prion-like Conformational Conversion*

    E-print Network

    Dokholyan, Nikolay V.

    Direct Observation of Protein Folding, Aggregation, and a Prion-like Conformational Conversion to -sheets precedes aggregation of proteins implicated in many diseases, including Alzheimer and prion, S. B. (1998) Proc. Natl. Acad. Sci. U. S. A. 95, 13363­ 13383) to account for prion infectivity

  15. Observational Learning of Academic and Social Behaviors during Small-Group Direct Instruction

    ERIC Educational Resources Information Center

    Ledford, Jennifer R.; Wolery, Mark

    2015-01-01

    Many studies have shown that small-group direct instruction is effective and efficient for teaching students with and without disabilities, although relatively few studies have been conducted with heterogeneous groups of preschool participants. In addition, previous studies have primarily assessed whether observational learning occurred for…

  16. Direct observation of ballistic Brownian motion on a single particle Rongxin Huang,1

    E-print Network

    Texas at Austin. University of

    1 Direct observation of ballistic Brownian motion on a single particle Rongxin Huang,1 Branimir and be replaced by ballistic motion. So far, an experimental verification of this prediction has been out of reach with 75 MHz bandwidth and sub-Ångstrom spatial precision. We report the first measurements of ballistic

  17. Easy flat embedding of oriented samples in hydrophilic resin (LR White) under controlled atmosphere: application allowing both nucleic acid hybridizations (CARD-FISH) and ultrastructural observations.

    PubMed

    Gros, Olivier; Maurin, Leslie C

    2008-01-01

    Hydrophilic resins present the advantage of making possible both hybridization experiments involving either antibodies or oligonucleotide probes and ultrastructural observations. Whereas various embedding protocols are available, only very few concern flat-embedded preparations. In this study we describe an easy protocol for flat embedding of small-oriented biological samples in hydrophilic resins (LR White). The most important constraints are (i) to polymerize the samples under argon-saturated atmosphere (avoiding oxygen which is an inhibitor of LR White polymerization) and (ii) to use transparent flat embedding molds. Two kinds of samples were analyzed: small pieces of large tissue that need to be accurately oriented for a valuable analysis and very small organisms such as free-living nematodes, which are very hard to investigate with conventional paraffin wax embedding techniques. Semi-thin sections strongly reinforce the quality of the observations from oligonucleotidic in situ hybridization experiments by reducing the background usually encountered in oligonucleotide probe hybridization experiments from sections. Such protocols could also permit a cheap alternative to the use of laser scanning confocal microscopes for oligonucleotidic in situ hybridization as in FISH and CARD-FISH experiments from histological sections. The interest of this embedding protocol is reinforced by the fact that molecular in situ hybridization experiments and ultrastructural observations from thin sections can be carried out from a single-small individual (<1mm in length) sample. PMID:18187186

  18. Direct observation of the transition from calcite to aragonite growth as induced by abalone shell proteins.

    PubMed

    Thompson, J B; Paloczi, G T; Kindt, J H; Michenfelder, M; Smith, B L; Stucky, G; Morse, D E; Hansma, P K

    2000-12-01

    The mixture of EDTA-soluble proteins found in abalone nacre are known to cause the nucleation and growth of aragonite on calcite seed crystals in supersaturated solutions of calcium carbonate. Past atomic force microscope studies of the interaction of these proteins with calcite crystals did not observe this transition because no information about the crystal polymorph on the surface was obtained. Here we have used the atomic force microscope to directly observe changes in the atomic lattice on a calcite seed crystal after the introduction of abalone shell proteins. The observed changes are consistent with a transition to (001) aragonite growth on a (1014) calcite surface. PMID:11106633

  19. Direct observation of size scaling and elastic interaction between nano-scale defects in collision cascades

    NASA Astrophysics Data System (ADS)

    Yi, X.; Sand, A. E.; Mason, D. R.; Kirk, M. A.; Roberts, S. G.; Nordlund, K.; Dudarev, S. L.

    2015-05-01

    Using in situ transmission electron microscopy, we have directly observed nano-scale defects formed in ultra-high–purity tungsten by low-dose high-energy self-ion irradiation at 30 K. At cryogenic temperature lattice defects have reduced mobility, so these microscope observations offer a window on the initial, primary damage caused by individual collision cascade events. Electron microscope images provide direct evidence for a power-law size distribution of nano-scale defects formed in high-energy cascades, with an upper size limit independent of the incident ion energy, as predicted by Sand et al. (EPL, 103 (2013) 46003). Furthermore, the analysis of pair distribution functions of defects observed in the micrographs shows significant intra-cascade spatial correlations consistent with strong elastic interaction between the defects.

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

    NASA Astrophysics Data System (ADS)

    Herique, A.; Kofman, W. W.

    2013-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    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

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

    PubMed

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

    2008-02-14

    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

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

    SciTech Connect

    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

    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.

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

    PubMed

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

    2012-06-23

    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

  5. Direct Observation of Field and Temperature Induced Domain Replication in Dipolar Coupled Perpendicular Anisotropy Films

    SciTech Connect

    Hauet, T.; Gunther, C.M.; Pfau, B.; Eisebitt, S.; Fischer, P.; Rick, R. L.; Thiele, J.-U.; Hellwig, O.; Schabes, M.E.

    2007-07-01

    Dipolar interactions in a soft/Pd/hard [CoNi/Pd]{sub 30}/Pd/[Co/Pd]{sub 20} multilayer system, where a thick Pd layer between two ferromagnetic units prevents direct exchange coupling, are directly revealed by combining magnetometry and state-of-the-art layer resolving soft x-ray imaging techniques with sub-100-nm spatial resolution. The domains forming in the soft layer during external magnetic field reversal are found to match the domains previously trapped in the hard layer. The low Curie temperature of the soft layer allows varying its intrinsic parameters via temperature and thus studying the competition with dipolar fields due to the domains in the hard layer. Micromagnetic simulations elucidate the role of [CoNi/Pd] magnetization, exchange, and anisotropy in the duplication process. Finally, thermally driven domain replication in remanence during temperature cycling is demonstrated.

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

    PubMed Central

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

    2011-01-01

    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. PMID:21364560

  7. Direct reconstruction of spherical harmonics from interferometer observations of the CMB polarization

    E-print Network

    Jaiseung Kim

    2009-04-06

    Interferometric observation of the CMB polarization can be expressed as a linear sum of spherical harmonic coefficients $a_{\\pm 2,lm}$ of the CMB polarization. The linear weight for $a_{\\pm 2,lm}$ depends on the observational configuration such as antenna pointing, baseline orientation, and spherical harmonic number $l,m$. Since an interferometer is sensitive over a finite range of multipoles, $a_{\\pm 2,lm}$ in the range can be determined by fitting $a_{\\pm 2,lm}$ for visibilities of various observational configurations. The formalism presented in this paper enables the determination of $a_{\\pm 2,lm}$ directly from spherical harmonic spaces without spherical harmonic transformation of pixellized maps. The result of its application to a simulated observation is presented with the formalism.

  8. Direct observation of shear deformation during equal channel angular pressing of pure aluminum

    SciTech Connect

    Shan, A. [Shanghai Jiao Tong Univ. (China)] [Shanghai Jiao Tong Univ. (China); Moon, I.G.; Ko, H.S.; Park, J.W. [Korean Inst. of Science and Technology, Seoul (Korea, Republic of). Div. of Metals] [Korean Inst. of Science and Technology, Seoul (Korea, Republic of). Div. of Metals

    1999-07-23

    Equal Channel Angular (ECA) pressing is a method through which intense plastic strain can be introduced into materials by simple shear. It is suggested that during ECA pressing, only simple shear deformation is introduced into the specimen. The degree of shear deformation can be well predicted by theory and is assumed to be uniform across the specimen except the top and end part. The theory had been proved to be correct by observation of ECA pressing of plasticine with a transparent plexiglass tool and by finite element modeling. However, direct observation of shear deformation had not yet been conducted in metallic materials. One difficulty in observing the shear deformation is that marks or scratches on the surface of the specimen will be erased or destroyed by severe surface deformation caused by friction. In this research, a special method is employed to eliminate the surface friction effect so that a clear shear deformation figure can be observed.

  9. Gravity Waves Generated by Convection: A New Idealized Model Tool and Direct Validation with Satellite Observations

    NASA Astrophysics Data System (ADS)

    Alexander, M. Joan; Stephan, Claudia

    2015-04-01

    In climate models, gravity waves remain too poorly resolved to be directly modelled. Instead, simplified parameterizations are used to include gravity wave effects on model winds. A few climate models link some of the parameterized waves to convective sources, providing a mechanism for feedback between changes in convection and gravity wave-driven changes in circulation in the tropics and above high-latitude storms. These convective wave parameterizations are based on limited case studies with cloud-resolving models, but they are poorly constrained by observational validation, and tuning parameters have large uncertainties. Our new work distills results from complex, full-physics cloud-resolving model studies to essential variables for gravity wave generation. We use the Weather Research Forecast (WRF) model to study relationships between precipitation, latent heating/cooling and other cloud properties to the spectrum of gravity wave momentum flux above midlatitude storm systems. Results show the gravity wave spectrum is surprisingly insensitive to the representation of microphysics in WRF. This is good news for use of these models for gravity wave parameterization development since microphysical properties are a key uncertainty. We further use the full-physics cloud-resolving model as a tool to directly link observed precipitation variability to gravity wave generation. We show that waves in an idealized model forced with radar-observed precipitation can quantitatively reproduce instantaneous satellite-observed features of the gravity wave field above storms, which is a powerful validation of our understanding of waves generated by convection. The idealized model directly links observations of surface precipitation to observed waves in the stratosphere, and the simplicity of the model permits deep/large-area domains for studies of wave-mean flow interactions. This unique validated model tool permits quantitative studies of gravity wave driving of regional circulation and provides a new method for future development of realistic convective gravity wave parameterizations.

  10. Direct Spectroscopic Observation of a Shallow Hydrogenlike Donor State in Insulating SrTiO3

    NASA Astrophysics Data System (ADS)

    Salman, Z.; Prokscha, T.; Amato, A.; Morenzoni, E.; Scheuermann, R.; Sedlak, K.; Suter, A.

    2014-10-01

    We present a direct spectroscopic observation of a shallow hydrogenlike muonium state in SrTiO3 which confirms the theoretical prediction that interstitial hydrogen may act as a shallow donor in this material. The formation of this muonium state is temperature dependent and appears below ˜70 K. From the temperature dependence we estimate an activation energy of ˜50 meV in the bulk and ˜23 meV near the free surface. The field and directional dependence of the muonium precession frequencies further supports the shallow impurity state with a rare example of a fully anisotropic hyperfine tensor. From these measurements we determine the strength of the hyperfine interaction and propose that the muon occupies an interstitial site near the face of the oxygen octahedron in SrTiO3. The observed shallow donor state provides new insight for tailoring the electronic and optical properties of SrTiO3-based oxide interface systems.

  11. Direct spectroscopic observation of a shallow hydrogenlike donor state in insulating SrTiO3.

    PubMed

    Salman, Z; Prokscha, T; Amato, A; Morenzoni, E; Scheuermann, R; Sedlak, K; Suter, A

    2014-10-10

    We present a direct spectroscopic observation of a shallow hydrogenlike muonium state in SrTiO(3) which confirms the theoretical prediction that interstitial hydrogen may act as a shallow donor in this material. The formation of this muonium state is temperature dependent and appears below ? 70K. From the temperature dependence we estimate an activation energy of ? 50 meV in the bulk and ? 23 meV near the free surface. The field and directional dependence of the muonium precession frequencies further supports the shallow impurity state with a rare example of a fully anisotropic hyperfine tensor. From these measurements we determine the strength of the hyperfine interaction and propose that the muon occupies an interstitial site near the face of the oxygen octahedron in SrTiO(3). The observed shallow donor state provides new insight for tailoring the electronic and optical properties of SrTiO(3)-based oxide interface systems. PMID:25375730

  12. Validation of simulated flow direction and hydraulic gradients with hydraulic head observations using open source GIS

    NASA Astrophysics Data System (ADS)

    Vandersteen, Katrijn; Rogiers, Bart; Gedeon, Matej

    2015-04-01

    It is recommended to check hydraulic gradients and flow directions predicted by a groundwater flow model that is calibrated solely with hydraulic head observations. It has been demonstrated in literature that substantial errors can be made when the model is not calibrated on these state variables. Therefore, in this work, we perform a validation of a steady-state groundwater flow model, representing part of the Neogene aquifer (60 km2) in Belgium. This model was developed and calibrated solely on groundwater head measurements, in the framework of the environmental impact assessment of the near surface repository for low- and intermediate-level short-lived waste, realized by ONDRAF/NIRAS at Dessel, Belgium. Horizontal flow directions, horizontal and vertical gradients for the entire area of the groundwater model were estimated from measurements at shallow monitoring wells within the groundwater flow model domain, and compared to the flow directions and vertical gradients predicted by the model. For obtaining horizontal flow directions and gradients, triangulation of groundwater levels was performed for combinations of three neighboring hydraulic head observations in the same hydrogeological layer within the model. The simulated equivalents at the same monitoring wells were used to repeat the same methodology, and calculate flow direction components. This analysis was performed in SAGA GIS and was visualized through QGIS. Comparison of the flow directions and flow gradients obtained from measurements and simulations gives an indication on the model performance. The calculations were performed for three sandy hydrogeological units used in the model. A similar procedure was performed for the vertical hydraulic head gradients, where any combination of two hydraulic head observations at the same location but at different levels within the aquifer were used to validate the vertical gradients predicted by the model. Besides model validation on average hydraulic heads, the variability of flow direction and hydraulic gradients in time was checked, by using the actually measured monthly time series, to verify the applicability of the steady-state modelling approach. This basic assessment of flow directions and gradients using open source GIS can be used to identify potential areas of interest, were more detailed investigations would be recommended.

  13. Direct observation of porous SiC formed by anodization in HF

    NASA Technical Reports Server (NTRS)

    Shor, Joseph S.; Grimberg, Ilana; Weiss, Ben-Zion; Kurtz, Anthony D.

    1993-01-01

    A process for forming porous SiC from single-crystal SiC wafers has been demonstrated. Porous SiC can be fabricated by anodizing n-type 6H-SiC in HF under UV illumination. TEM reveals pores of sizes 10-30 nm with interpore spacings ranging from roughly 5 to 150 nm. This is the first reported direct observation of porous SiC formation.

  14. Direct time-domain observation of laser pulse filaments in transparent media

    SciTech Connect

    Dachraoui, H.; Oberer, C.; Michelswirth,; Heinzmann, U. [Molecular and Surface Physics, Faculty of Physics, Bielefeld University, D-33615 Bielefeld (Germany)

    2010-10-15

    The interplay among self-focusing, energy depletion, and plasma formation is fundamental to the understanding of laser-matter interaction. In this article, we present the first direct time-resolved observations of the propagation of intense femtosecond laser pulses experiencing conical emission, self-focusing, self-guiding, beam filamentation, plasma defocusing, and continuum generation in wide-band-gap dielectrics. We demonstrate that continuum generation involves different mechanisms as a function of deposited energy.

  15. Direct observation of the orientational Kerr effect in the self-focusing of picosecond pulses.

    NASA Technical Reports Server (NTRS)

    Reintjes, J.; Carman, R. L.

    1972-01-01

    Direct measurements of the relaxation time of the birefringence within the self-focusing region of mode-locked laser pulses in several anisotropic liquids establish the importance of the orientational Kerr effect in the picosecond time regime. This result leads to some speculation as to the origin of the high degree of symmetry in the phase-modulated filament spectra observed with picosecond pulses.

  16. Direct observation of a tangential electric field component at the magnetopause

    Microsoft Academic Search

    F. S. Mozer; R. B. Torbert; U. V. Fahleson; C.-G. Falthammar; A. Gonfalone; A. Pedersen

    1979-01-01

    Results are presented for direct, in situ measurements of the quasi-static electric field at and near the magnetopause, in the magnetosheath, bow shock, and solar wind, obtained by the ISEE-1 satellite. Both the large-scale average electric field and the fine-scale field observed during a magnetopause crossing show the existence of significant tangential electric field components on both sides of the

  17. Class I Methanol Maser Observations at 44 GHz in the Direction of some SNRs and SFRs

    Microsoft Academic Search

    G. M. Larionov; I. D. Litovchenko

    2011-01-01

    The results of searching for class I methanol maser emission in the interstellar medium are presented. Observations at Onsala 20-m radio telescope at 44 GHz in methanol transition 7_0-6_1A has been conducted in the direction of different types of objects of the northern hemisphere: in a little-studied region of maser emission G27.4-0.2, in some supernova remnants, in high mass protostars

  18. Direct observation of intracluster reactions induced in (CF3I) n clusters by femtosecond ultraviolet radiation

    NASA Astrophysics Data System (ADS)

    Apatin, V. M.; Kompanets, V. O.; Lokhman, V. N.; Ogurok, N.-D. D.; Poydashev, D. G.; Ryabov, E. A.; Chekalin, S. V.

    2011-12-01

    Intracluster reactions that are induced in (CF3I) n clusters by femtosecond ultraviolet radiation, including the reaction of the formation of the I{2/+} molecular ion, have been directly observed. It has been shown that there are two channels of the formation of I{2/+} ions with the characteristic times ?1 ? 1 ps and ?2 ? 7 ps. A model of these reactions has been proposed that is in good agreement with the experimental data.

  19. Direct observation of charge inversion by multivalent ions as a universal electrostatic phenomenon.

    PubMed

    Besteman, K; Zevenbergen, M A G; Heering, H A; Lemay, S G

    2004-10-22

    We have directly observed reversal of the polarity of charged surfaces in water upon the addition of trivalent and quadrivalent ions using atomic force microscopy. The bulk concentration of multivalent ions at which charge inversion reversibly occurs depends only very weakly on the chemical composition, surface structure, size, and lipophilicity of the ions, but is very sensitive to their valence. These results support the theoretical proposal that spatial correlations between ions are the driving mechanism behind charge inversion. PMID:15525062

  20. Direct Observation of Ferroelectric Domains in LiTaO3 Using Environmental Scanning Electron Microscopy

    Microsoft Academic Search

    Shining Zhu; Wenwu Cao

    1997-01-01

    Direct observation of ferroelectric domain structures in LiTaO3 crystal, without etching or surface coating, has been realized by using environmental scanning electron microscopy in secondary electron emission mode. The new method can nondestructively provide domain contrast image at submicron resolution, and the domain contrast image is very stable. Conditions for best domain contrast of LiTaO3 crystals have been established.

  1. Direct observations of N2O5 reactivity on ambient aerosol particles

    Microsoft Academic Search

    Timothy H. Bertram; Joel A. Thornton; Theran P. Riedel; Ann M. Middlebrook; Roya Bahreini; Timothy S. Bates; Patricia K. Quinn; Derek J. Coffman

    2009-01-01

    N2O5 reactivity has been measured directly for the first time on ambient aerosol particles using an entrained aerosol flow reactor coupled to a custom-built chemical ionization mass spectrometer at two urban locations during summer. The observed N2O5 reactivity is a strong function of both relative humidity (RH) and particle chemical composition. We show that particulate organic mass loadings, together with

  2. Direct observation of induction period of MTO process with consecutive pulse reaction system

    Microsoft Academic Search

    Yingxu Wei; Dazhi Zhang; Fuxiang Chang; Zhongmin Liu

    2007-01-01

    The initial transformation of methanol over HZSM-5 catalyst was investigated by a consecutive pulse reaction system. The reactant–catalyst contact time influenced the initial methanol transformation and the performances implied methanol reaction in induction period or under steady-state condition. The induction period, in which an organic-free HZSM-5 catalyst could be transferred to a working catalyst, were directly observed. The analysis result

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

    PubMed

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

    2014-01-01

    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

  4. Increasing Reliability of Direct Observation Measurement Approaches in Emotional and/or Behavioral Disorders Research Using Generalizability Theory

    ERIC Educational Resources Information Center

    Gage, Nicholas A.; Prykanowski, Debra; Hirn, Regina

    2014-01-01

    Reliability of direct observation outcomes ensures the results are consistent, dependable, and trustworthy. Typically, reliability of direct observation measurement approaches is assessed using interobserver agreement (IOA) and the calculation of observer agreement (e.g., percentage of agreement). However, IOA does not address intraobserver…

  5. Warming experiments elucidate the drivers of observed directional changes in tundra vegetation

    PubMed Central

    Hollister, Robert D; May, Jeremy L; Kremers, Kelseyann S; Tweedie, Craig E; Oberbauer, Steven F; Liebig, Jennifer A; Botting, Timothy F; Barrett, Robert T; Gregory, Jessica L

    2015-01-01

    Few studies have clearly linked long-term monitoring with in situ experiments to clarify potential drivers of observed change at a given site. This is especially necessary when findings from a site are applied to a much broader geographic area. Here, we document vegetation change at Barrow and Atqasuk, Alaska, occurring naturally and due to experimental warming over nearly two decades. An examination of plant cover, canopy height, and community indices showed more significant differences between years than due to experimental warming. However, changes with warming were more consistent than changes between years and were cumulative in many cases. Most cases of directional change observed in the control plots over time corresponded with a directional change in response to experimental warming. These included increases in canopy height and decreases in lichen cover. Experimental warming resulted in additional increases in evergreen shrub cover and decreases in diversity and bryophyte cover. This study suggests that the directional changes occurring at the sites are primarily due to warming and indicates that further changes are likely in the next two decades if the regional warming trend continues. These findings provide an example of the utility of coupling in situ experiments with long-term monitoring to accurately document vegetation change in response to global change and to identify the underlying mechanisms driving observed changes. PMID:26140204

  6. Quantifying the Hawthorne Effect in Hand Hygiene Compliance Through Comparing Direct Observation With Automated Hand Hygiene Monitoring.

    PubMed

    Hagel, Stefan; Reischke, Jana; Kesselmeier, Miriam; Winning, Johannes; Gastmeier, Petra; Brunkhorst, Frank M; Scherag, André; Pletz, Mathias W

    2015-08-01

    OBJECTIVE To quantify the Hawthorne effect of hand hygiene performance among healthcare workers using direct observation. DESIGN Prospective observational study. SETTING Intensive care unit, university hospital. METHODS Direct observation of hand hygiene compliance over 48 audits of 2 hours each. Simultaneously, hand hygiene events (HHEs) were recorded using electronic alcohol-based handrub dispensers. Directly observed and electronically recorded HHEs during the 2 hours of direct observation were compared using Spearman correlations and Bland-Altman plots. To quantify the Hawthorne effect, we compared the number of electronically recorded HHEs during the direct observation periods with the re-scaled electronically recorded HHEs in the 6 remaining hours of the 8-hour working shift. RESULTS A total of 3,978 opportunities for hand hygiene were observed during the 96 hours of direct observation. Hand hygiene compliance was 51% (95% CI, 49%-53%). There was a strong positive correlation between directly observed compliance and electronically recorded HHEs (?=0.68 [95% CI, 0.49-0.81], P<.0001). In the 384 hours under surveillance, 4,180 HHEs were recorded by the electronic dispensers. Of those, 2,029 HHEs were recorded during the 96 hours in which direct observation was also performed, and 2,151 HHEs were performed in the remaining 288 hours of the same working shift that were not under direct observation. Healthcare workers performed 8 HHEs per hour when not under observation compared with 21 HHEs per hour during observation. CONCLUSIONS Directly and electronically observed HHEs were in agreement. We observed a marked influence of the Hawthorne effect on hand hygiene performance. Infect Control Hosp Epidemiol 2015;36(8):957-962. PMID:25903555

  7. Direct observation of imprinted antiferromagnetic vortex state in CoO/Fe/Ag(001) disks

    SciTech Connect

    Wu, J.; Carlton, D.; Park, J. S.; Meng, Y.; Arenholz, E.; Doran, A.; Young, A.T.; Scholl, A.; Hwang, C.; Zhao, H. W.; Bokor, J.; Qiu, Z. Q.

    2010-12-21

    In magnetic thin films, a magnetic vortex is a state in which the magnetization vector curls around the center of a confined structure. A vortex state in a thin film disk, for example, is a topological object characterized by the vortex polarity and the winding number. In ferromagnetic (FM) disks, these parameters govern many fundamental properties of the vortex such as its gyroscopic rotation, polarity reversal, core motion, and vortex pair excitation. However, in antiferromagnetic (AFM) disks, though there has been indirect evidence of the vortex state through observations of the induced FM-ordered spins in the AFM disk, they have never been observed directly in experiment. By fabricating single crystalline NiO/Fe/Ag(001) and CoO/Fe/Ag(001) disks and using X-ray Magnetic Linear Dichroism (XMLD), we show direct observation of the vortex state in an AFM disk of AFM/FM bilayer system. We observe that there are two types of AFM vortices, one of which has no analog in FM structures. Finally, we show that a frozen AFM vortex can bias a FM vortex at low temperature.

  8. Global observations of the spectrally resolved direct effect of aerosols over clouds

    NASA Astrophysics Data System (ADS)

    de Graaf, M.; Tilstra, G.; Stammes, P.

    2011-12-01

    The direct radiative effect of absorbing aerosols in cloudy scenes is currently not well constrained. The simultaneous observation of both clouds and aerosols is seriously limited due to their heterogeneous distribution in both space and time. Space-based observations have the potential of monitoring cloud and aerosol distributions on a daily basis, but most current satellite aerosol retrieval algorithms rely on cloud screening before retrieving aerosol information. Furthermore, results often depend strongly on aerosol micro-physical property assumptions. With the space-borne spectrometer ENVISAT/SCIAMACHY, that measures 92% of the solar energy spectrum incident on the Earth's atmosphere, the aerosol direct effect can be quantified directly, avoiding most of these limitations. The absorption of radiation by small, absorbing aerosols is large in the ultraviolet (UV), and can be detected using UV-reflectance measurements, even in the presence of clouds. The aerosol absorption decreases quickly with increasing wavelength and cloud optical thickness and cloud droplet size can be retrieved in the near-infrared, where aerosol effects are sufficiently small. These retrieved cloud parameters can be used to find a modelled unpolluted cloud reflectance spectrum for the scene (with the aerosols removed), using pre-computed data bases from a radiative transfer model. In this way, cloud and aerosol effects can be separated for the polluted cloud scene. The spectrally resolved direct effect can be determined by comparison of the measured polluted scene reflectance spectrum and the modelled clean cloud reflectance spectrum. Aerosol micro-physical property assumptions are avoided through the modelling of pure cloud spectra only. Although the global coverage of SCIAMACHY is only once every six days, over 8 years of global reflectance spectra and direct effect of aerosols over clouds data are available from this method, which will be presented here.

  9. Video Allows Young Scientists New Ways to Be Seen

    ERIC Educational Resources Information Center

    Park, John C.

    2009-01-01

    Science is frequently a visual endeavor, dependent on direct or indirect observations. Teachers have long employed motion pictures in the science classroom to allow students to make indirect observations, but the capabilities of digital video offer opportunities to engage students in active science learning. Not only can watching a digital video…

  10. Investigating common clinical presentations in first opinion small animal consultations using direct observation

    PubMed Central

    Robinson, N. J.; Dean, R. S.; Cobb, M.; Brennan, M. L.

    2015-01-01

    Understanding more about the clinical presentations encountered in veterinary practice is vital in directing research towards areas relevant to practitioners. The aim of this study was to describe all problems discussed during a convenience sample of consultations using a direct observation method. A data collection tool was used to gather data by direct observation during small animal consultations at eight sentinel practices. Data were recorded for all presenting and non-presenting specific health problems discussed. A total of 1901 patients were presented with 3206 specific health problems discussed. Clinical presentation varied widely between species and between presenting and non-presenting problems. Skin lump, vomiting and inappetence were the most common clinical signs reported by the owner while overweight/obese, dental tartar and skin lump were the most common clinical examination findings. Skin was the most frequently affected body system overall followed by non-specific problems then the gastrointestinal system. Consultations are complex, with a diverse range of different clinical presentations seen. Considering the presenting problem only may give an inaccurate view of the veterinary caseload, as some common problems are rarely the reason for presentation. Understanding the common diagnoses made is the next step and will help to further focus questions for future research. PMID:25564472

  11. In Situ Observation of Directed Nanoparticle Aggregation During the Synthesis of Ordered Nanoporous Metal in Soft Templates

    SciTech Connect

    Parent, Lucas R.; Robinson, David B.; Cappillino, Patrick J.; Hartnett, Ryan J.; Abellan, Patricia; Evans, James E.; Browning, Nigel D.; Arslan, Ilke

    2014-01-17

    The prevalent approach to developing new nanomaterials is a trial-and-error process of iteratively altering synthesis procedures and then characterizing the resulting nanostructures. This is fundamentally limited in that the growth processes that occur during synthesis can be inferred only from the final synthetic structure. Directly observing real-time nanomaterial growth provides unprecedented insight into the relationship between synthesis conditions and product evolution and facilitates a mechanistic approach to nanomaterial development. Here, we use in situ liquid-stage scanning transmission electron microscopy to observe the growth of mesoporous palladium in a solvated block copolymer (BCP) template under various synthesis conditions, and we ultimately determined a refined synthesis procedure that yields extended structures with ordered pores. We found that after sufficient drying time of the casting solvent (tetrahydrofuran, THF), the BCP assembles into a rigid, cylindrical micelle array with a high degree of short-range order but poor long-range order. Upon slowing the THF evaporation rate using a solvent-vapor anneal step, the long-range order was greatly improved. The electron beam induces nucleation of small particles in the aqueous phase around the micelles. The small particles then flocculate and grow into denser structures that surround, but do not overgrow, the micelles, forming an ordered mesoporous structure. The microscope observations revealed that pore disorder can be addressed prior to metal reduction and is not invariably induced by the Pd growth process itself, allowing for more rapid optimization of the synthetic method.

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

    PubMed

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

    1994-08-01

    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

  13. Direct Observation of Aggregative Nanoparticle Growth: Kinetic Modeling of the Size Distribution and Growth Rate

    SciTech Connect

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

    2014-01-08

    ABSTRACT: 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.

  14. Direct Observation of Chiral Topological Solitons in 1D Charge-Density Waves

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Hwan; Cheon, Sangmo; Lee, Sung-Hoon; Yeom, Han Woong

    2015-03-01

    Macroscopic and classical solitons are easily and ubiquitously found, from tsunami to blood pressure pulses, but those in microscopic scale are hard to observe. While the existence of such topological solitons were predicted theoretically and evidenced indirectly by the transport and infrared spectroscopy measurements, the direct observation has been hampered by their high mobility and small dimension. In this talk, we show direct observation of topological solitons in the quasi-1D charge-density wave (CDW) ground state of indium atomic wires, which are consisting of interacting double Peierls chains. Such solitons exhibit a characteristic spatial variation of the CDW amplitudes as expected from the electronic structure. Furthermore, these solitons have an exotic hidden topology originated by topologically different 4-fold degenerate CDW ground states. Their exotic topology leads to the chirality of 1D topological solitons through interaction between two solitons in the double Peierls chains. Detailed scanning tunneling microscopy and spectroscopy reveal their chiral nature at the atomic scale. This work paves the avenue toward the microscopic exploitation of the peculiar properties of nanoscale chiral solitons.

  15. Direct Observation of Coherent Oscillations in Solution due to Microheterogeneous Environment

    NASA Astrophysics Data System (ADS)

    Das, Dipak Kumar; Makhal, Krishnandu; Bandyopadhyay, Soumendra Nath; Goswami, Debabrata

    2014-08-01

    We report, for the first time, direct observation of coherent oscillations in the ground-state of IR775 dye due to microheterogeneous environment. Using ultrafast near-infrared degenerate pump-probe technique centered at 800 nm, we present the dynamics of IR775 in a binary mixture of methanol and chloroform at ultra-short time resolution of 30 fs. The dynamics of the dye in binary mixtures, in a time-scale of a few fs to ~740 ps, strongly varies as a function of solvent composition (volume fraction). Multi-oscillation behavior of the coherent vibration was observed, which increased with decreasing percentage of methanol in the dye mixture. Maximum number of damped oscillations were observed in 20% methanol. The observed vibrational wavepacket motion in the ground-state is periodic in nature. We needed two cosine functions to fit the coherent oscillation data as two different solvents were used. Dynamics of the dye molecule in binary mixtures can be explained by wavepacket motion in the ground potential energy surface. More is the confinement of the dye molecule in binary mixtures, more is the number of damped oscillations. The vibrational cooling time, ?2, increases with increase in the confinement of the system. The observed wavepacket oscillations in ground-state dynamics continued until 1.6 ps.

  16. Direct Observation of Coherent Oscillations in Solution due to Microheterogeneous Environment

    PubMed Central

    Das, Dipak Kumar; Makhal, Krishnandu; Bandyopadhyay, Soumendra Nath; Goswami, Debabrata

    2014-01-01

    We report, for the first time, direct observation of coherent oscillations in the ground-state of IR775 dye due to microheterogeneous environment. Using ultrafast near-infrared degenerate pump-probe technique centered at 800?nm, we present the dynamics of IR775 in a binary mixture of methanol and chloroform at ultra-short time resolution of 30?fs. The dynamics of the dye in binary mixtures, in a time-scale of a few fs to ~740?ps, strongly varies as a function of solvent composition (volume fraction). Multi-oscillation behavior of the coherent vibration was observed, which increased with decreasing percentage of methanol in the dye mixture. Maximum number of damped oscillations were observed in 20% methanol. The observed vibrational wavepacket motion in the ground-state is periodic in nature. We needed two cosine functions to fit the coherent oscillation data as two different solvents were used. Dynamics of the dye molecule in binary mixtures can be explained by wavepacket motion in the ground potential energy surface. More is the confinement of the dye molecule in binary mixtures, more is the number of damped oscillations. The vibrational cooling time, ?2, increases with increase in the confinement of the system. The observed wavepacket oscillations in ground-state dynamics continued until 1.6?ps. PMID:25130204

  17. Direct observation of coherent oscillations in solution due to microheterogeneous environment.

    PubMed

    Das, Dipak Kumar; Makhal, Krishnandu; Bandyopadhyay, Soumendra Nath; Goswami, Debabrata

    2014-01-01

    We report, for the first time, direct observation of coherent oscillations in the ground-state of IR775 dye due to microheterogeneous environment. Using ultrafast near-infrared degenerate pump-probe technique centered at 800?nm, we present the dynamics of IR775 in a binary mixture of methanol and chloroform at ultra-short time resolution of 30?fs. The dynamics of the dye in binary mixtures, in a time-scale of a few fs to ~740?ps, strongly varies as a function of solvent composition (volume fraction). Multi-oscillation behavior of the coherent vibration was observed, which increased with decreasing percentage of methanol in the dye mixture. Maximum number of damped oscillations were observed in 20% methanol. The observed vibrational wavepacket motion in the ground-state is periodic in nature. We needed two cosine functions to fit the coherent oscillation data as two different solvents were used. Dynamics of the dye molecule in binary mixtures can be explained by wavepacket motion in the ground potential energy surface. More is the confinement of the dye molecule in binary mixtures, more is the number of damped oscillations. The vibrational cooling time, ??, increases with increase in the confinement of the system. The observed wavepacket oscillations in ground-state dynamics continued until 1.6?ps. PMID:25130204

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

    NASA Astrophysics Data System (ADS)

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

    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.

  19. A Flexible Reporter System for Direct Observation and Isolation of Cancer Stem Cells

    PubMed Central

    Tang, Binwu; Raviv, Asaf; Esposito, Dominic; Flanders, Kathleen C.; Daniel, Catherine; Nghiem, Bao Tram; Garfield, Susan; Lim, Langston; Mannan, Poonam; Robles, Ana I.; Smith, William I.; Zimmerberg, Joshua; Ravin, Rea; Wakefield, Lalage M.

    2014-01-01

    Summary Many tumors are hierarchically organized with a minority cell population that has stem-like properties and enhanced ability to initiate tumorigenesis and drive therapeutic relapse. These cancer stem cells (CSCs) are typically identified by complex combinations of cell-surface markers that differ among tumor types. Here, we developed a flexible lentiviral-based reporter system that allows direct visualization of CSCs based on functional properties. The reporter responds to the core stem cell transcription factors OCT4 and SOX2, with further selectivity and kinetic resolution coming from use of a proteasome-targeting degron. Cancer cells marked by this reporter have the expected properties of self-renewal, generation of heterogeneous offspring, high tumor- and metastasis-initiating activity, and resistance to chemotherapeutics. With this approach, the spatial distribution of CSCs can be assessed in settings that retain microenvironmental and structural cues, and CSC plasticity and response to therapeutics can be monitored in real time. PMID:25497455

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

    NASA Astrophysics Data System (ADS)

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

    2005-07-01

    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.

  1. Direct observation of isothermal adsorption and desorption processes of CO on the Ni(100) surface

    NASA Astrophysics Data System (ADS)

    Takagi, N.; Yoshinobu, J.; Kawai, Maki

    1993-11-01

    Isothermal adsorption and desorption processes of CO on the Ni(100) surface have been investigated using time-resolved infrared reflection absorption spectroscopy at several temperatures from 310 to 415 K. The following information on the kinetics of CO adsorption and desorption is obtained by direct observation of the adsorbed CO. The initial sticking coefficient is found to be constant within this temperature range. The desorption energy and the preexponential factor are determined to be 127 kJ mol -1 and 1.6 × 10 14 s -1, respectively.

  2. Direct observation of medium-range crystalline order in granular liquids near the glass transition.

    PubMed

    Watanabe, Keiji; Tanaka, Hajime

    2008-04-18

    Collective behavior of driven granular matter is often strikingly analogous to that of thermal systems. Here we use a vibrated quasi-two-dimensional granular matter as a model system and investigate the mechanism of the liquid-glass transition. We demonstrate by direct observation the existence of long-lived medium-range crystalline order, which is found to be closely related to both dynamic heterogeneity and slow dynamics. Our findings are remarkably similar to recent numerical results on model thermal liquids and thus open an intriguing possibility of understanding the dynamic arrest in both thermal and athermal systems in a unified manner. PMID:18518153

  3. Direct observation of surface plasmon vortex and subwavelength focusing with arbitrarily-tailored intensity patterns

    NASA Astrophysics Data System (ADS)

    Ku, Chen-Ta; Lin, Heh-Nan; Huang, Chen-Bin

    2015-02-01

    Surface plasmon (SP) vortices typically have annular intensity patterns. Here we show that fractional SP vortices with arbitrary, asymmetric intensity patterns can be synthesized via simple geometric arrangements. We provide the direct experimental observations over the existence of fractional SP vortices. Triangular SP vortex intensities are synthesized by circularly polarized plane waves. On the other hand, subwavelength focusing with user-desired patterns is also experimentally demonstrated. The synthesized SP vortex and focusing patterns are experimentally measured using a near-field scanning optical microscope with uncoated fiber probe and are found in good agreements as compared to numerical results.

  4. Direct experimental observation of periodic intensity modulation along a straight hollow-core optical waveguide

    SciTech Connect

    Pfeifer, T.; Downer, M. C. [Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States)

    2007-05-15

    We report the direct observation of periodic intensity modulation of a laser pulse propagating in a hollow-core waveguide. A series of equally spaced plasma sparks along the gas-filled capillary is produced. This effect can be explained by the beating of different fiber modes, which are excited by controlling the size of the focal spot at the capillary entrance. As compared with an artificial modulated waveguide structure, our presented approach represents an easier and more flexible quasi-phase-matching scheme for nonlinear-optical frequency conversion.

  5. Direct observation of grain boundary Schottky barrier behaviour in zinc oxide varistor material

    NASA Astrophysics Data System (ADS)

    Russell, J. D.; Halls, D. C.; Leach, C.

    1995-05-01

    Several models have been proposed to described the structure of grain boundaries in ZnO in order to explain its varisting properties. Common to most of these models are back-to-back Schottky barriers at ZnO grain boundaries. Although demonstrating the presence of Schottky barriers is crucial to accepting some of these models, to date no direct experimental observation has been made of such characteristics in ZnO. In this paper, the localized occurrence of such grain boundary contrast in the charge collection (CC) mode of the scanning electron microscope (SEM) is described and linescan profiles with the form expected from the available predictive models are compared.

  6. Directly observed interaction within adolescent romantic relationships: What have we learned?

    PubMed Central

    Welsh, Deborah P; Shulman, Shmuel

    2008-01-01

    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 family relationships, new understandings of the distinctive nature of adolescent romantic relationships, and gender issues are clarified by this body of papers. Together, these papers move the scholarly field forward and generate new lines of questions for future investigators. PMID:18986697

  7. Vertical structure and transport of the Antarctic Circumpolar Current in Drake Passage from direct velocity observations

    NASA Astrophysics Data System (ADS)

    Firing, Yvonne L.; Chereskin, Teresa K.; Mazloff, Matthew R.

    2011-08-01

    The structure of the Antarctic Circumpolar Current (ACC) in Drake Passage is examined using 4.5 years of shipboard acoustic Doppler current profiler (ADCP) velocity data. The extended 1000 m depth range available from the 38 kHz ADCP allows us to investigate the vertical structure of the current. The mean observed current varies slowly with depth, while eddy kinetic energy and shear variance exhibit strong depth dependence. Objectively mapped streamlines are self-similar with depth, consistent with an equivalent barotropic structure. Vertical wavenumber spectra of observed currents and current shear reveal intermediate wavenumber anisotropy and rotation indicative of downward energy propagation above 500 m and upward propagation below 500 m. The mean observed transport of the ACC in the upper 1000 m is estimated at 95 ± 2 Sv or 71% of the canonical total transport of 134 Sv. Mean current speeds in the ACC jets remain quite strong at 1000 m, 10-20 cm s-1. Vertical structure functions to describe the current and extrapolate below 1000 m are explored with the aid of full-depth profiles from lowered ADCP and a 3 year mean from the Southern Ocean State Estimate (SOSE). A number of functions, including an exponential, are nearly equally good fits to the observations, explaining >75% of the variance. Fits to an exponentially decaying function can be extrapolated to give an estimate of 154 ± 38 Sv for the full-depth transport.

  8. Direct observation of liquid nucleus growth in homogeneous melting of colloidal crystals

    PubMed Central

    Wang, Ziren; Wang, Feng; Peng, Yi; Han, Yilong

    2015-01-01

    The growth behaviour of liquid nucleus is crucial for crystal melting, but its kinetics is difficult to predict and remains challenging in experiment. Here we directly observed the growth of individual liquid nuclei in homogeneous melting of three-dimensional superheated colloidal crystals with single-particle dynamics by video microscopy. The growth rate of nucleus at weak superheating is well fitted by generalizing the Wilson–Frenkel law of crystallization to melting and including the surface tension effects and non-spherical-shape effects. As the degree of superheating increases, the growth rate is enhanced by nucleus shape fluctuation, nuclei coalescence and multimer attachment. The results provide new guidance for the refinement of nucleation theory, especially for the poorly understood strong-superheating regime. The universal Lindemann parameter observed at the superheat limit and solid–liquid interfaces indicates a connection between homogeneous and heterogeneous melting. PMID:25897801

  9. Direct observation of single Ostwald ripening processes by molecular dynamics simulation.

    PubMed

    Kraska, Thomas

    2008-10-01

    Ostwald ripening is an important growth process in many scientific disciplines ranging from material science, geology, biophysics, and product formulation. Here ripening of argon clusters in a vapor phase is observed directly in constant energy molecular dynamics simulations serving as a model system for large-time scale ripening processes. Starting from an initial metastable equilibrium between the vapor phase and two clusters Ostwald ripening is initiated by the addition of kinetic energy. This mimics local thermal fluctuations in a larger system. It appears that there is not necessarily a close encounter of two clusters before ripening sets in. Also no static density bridge between two ripening clusters is observed. The onset of ripening is rather related to the different evaporation dynamics of clusters of different size. It can start at the moment energy is added or with some delay, depending on the difference in cluster size and dynamics. PMID:18783194

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

    USGS Publications Warehouse

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

    1994-01-01

    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.

  11. Direct observation of TALE protein dynamics reveals a two-state search mechanism

    PubMed Central

    Cuculis, Luke; Abil, Zhanar; Zhao, Huimin; Schroeder, Charles M.

    2015-01-01

    Transcription activator-like effector (TALE) proteins are a class of programmable DNA-binding proteins for which the fundamental mechanisms governing the search process are not fully understood. Here we use single-molecule techniques to directly observe TALE search dynamics along DNA templates. We find that TALE proteins are capable of rapid diffusion along DNA using a combination of sliding and hopping behaviour, which suggests that the TALE search process is governed in part by facilitated diffusion. We also observe that TALE proteins exhibit two distinct modes of action during the search process—a search state and a recognition state—facilitated by different subdomains in monomeric TALE proteins. Using TALE truncation mutants, we further demonstrate that the N-terminal region of TALEs is required for the initial non-specific binding and subsequent rapid search along DNA, whereas the central repeat domain is required for transitioning into the site-specific recognition state. PMID:26027871

  12. Direct observation of quark-hadron duality in the free neutron F2 structure function

    NASA Astrophysics Data System (ADS)

    Niculescu, I.; Niculescu, G.; Melnitchouk, W.; Arrington, J.; Christy, M. E.; Ent, R.; Griffioen, K. A.; Kalantarians, N.; Keppel, C. E.; Kuhn, S.; Tkachenko, S.; Zhang, J.

    2015-05-01

    Using the recently published data from the BONuS (Barely Off-shell Nucleon Structure) experiment at Jefferson Lab, which utilized a spectator tagging technique to extract the inclusive electron-free neutron scattering cross section, we obtain the first direct observation of quark-hadron duality in the neutron F2 structure function. The data are used to reconstruct the lowest few (N =2 , 4, and 6) moments of F2 in the three prominent nucleon resonance regions, as well as the moments integrated over the entire resonance region. Comparison with moments computed from global parametrizations of parton distribution functions suggest that quark-hadron duality holds locally for the neutron in the second and third resonance regions down to Q2?1 GeV2 , with violations possibly up to 20% observed in the first resonance region.

  13. Deadbeat flux level control of direct field-oriented high horse power induction servo motor using adaptive rotor flux observer

    Microsoft Academic Search

    Kouki Matsuse; Y. Takokoro

    1993-01-01

    A flux level deadbeat control of direct field oriented high-power induction servo motor drives using an adaptive rotor flux observer is presented. In this system, an adaptive rotor flux observer of a full-order type is used not only to construct the direct field oriented controller but also to identify the stator and rotor resistances of the servo motor. The rotor

  14. Direct nano-scale observations of carbon mineralization during brucite dissolution (Invited)

    NASA Astrophysics Data System (ADS)

    Hoevelmann, J.; Putnis, C. V.; Ruiz Agudo, E.; Austrheim, H.

    2013-12-01

    Aqueous mineral carbonation for ex situ CO2 sequestration involves coupled dissolution and precipitation processes occurring at the mineral-fluid interface. Critical insight into the reaction mechanisms is therefore gained from direct nano-scale observations of carbonation reactions using advanced analytical techniques such as Atomic Force Microscopy (AFM). Here we present a series of in situ an ex situ AFM experiments on the dissolution and carbonation of brucite [Mg(OH)2] at varying pH (2-12), temperature (23-40°C), aqueous NaHCO3 concentration (10-5-1 M), and PCO2 (0-1 atm). In all experiments, brucite dissolution proceeded by the formation and spreading of etch pits with equilateral triangular shapes. Dissolution rates increased with decreasing pH and increasing NaHCO3 concentration. Simultaneously with dissolution of brucite, the growth of a Mg-carbonate phase (probably dypingite) was directly observed. In NaHCO3 solutions (pH 7.2 - 9.3,), precipitation of Mg-carbonates was limited. Enhanced precipitation was, however, observed in acidified NaHCO3 solutions (pH 5, DIC ? 25.5 mM) and in solutions that were equilibrated under a CO2 atmosphere (pH 4, DIC ? 25.2 mM). Nucleation predominantly occurred in areas of high dissolution, such as deep step edges, suggesting that the carbonation reaction is locally diffusion-transport controlled within a fluid-mineral boundary layer and is the result of interface-coupled dissolution-precipitation. More extensive particle growth was also observed after ex situ experiments lasting for several hours. This AFM study contributes to an improved understanding of the mechanism of aqueous brucite carbonation at low temperature and PCO2 conditions and has implications for the development of mineral carbonation schemes involving brucite as well as silicates (e.g., serpentines) that contain 'brucite-layers' as structural components.

  15. Direct observation of the translocation mechanism of transcription termination factor Rho

    PubMed Central

    Gocheva, Veronika; Le Gall, Antoine; Boudvillain, Marc; Margeat, Emmanuel; Nollmann, Marcelo

    2015-01-01

    Rho is a ring-shaped, ATP-fueled motor essential for remodeling transcriptional complexes and R-loops in bacteria. Despite years of research on this fundamental model helicase, key aspects of its mechanism of translocation remain largely unknown. Here, we used single-molecule manipulation and fluorescence methods to directly monitor the dynamics of RNA translocation by Rho. We show that the efficiency of Rho activation is strongly dependent on the force applied on the RNA but that, once active, Rho is able to translocate against a large opposing force (at least 7 pN) by a mechanism involving ‘tethered tracking’. Importantly, the ability to directly measure dynamics at the single-molecule level allowed us to determine essential motor properties of Rho. Hence, Rho translocates at a rate of ?56 nt per second under our experimental conditions, which is 2–5 times faster than velocities measured for RNA polymerase under similar conditions. Moreover, the processivity of Rho (?62 nt at a 7 pN opposing force) is large enough for Rho to reach termination sites without dissociating from its RNA loading site, potentially increasing the efficiency of transcription termination. Our findings unambiguously establish ‘tethered tracking’ as the main pathway for Rho translocation, support ‘kinetic coupling’ between Rho and RNA polymerase during Rho-dependent termination, and suggest that forces applied on the nascent RNA transcript by cellular substructures could have important implications for the regulation of transcription and its coupling to translation in vivo. PMID:25662222

  16. Social communication with virtual agents: The effects of body and gaze direction on attention and emotional responding in human observers.

    PubMed

    Marschner, Linda; Pannasch, Sebastian; Schulz, Johannes; Graupner, Sven-Thomas

    2015-08-01

    In social communication, the gaze direction of other persons provides important information to perceive and interpret their emotional response. Previous research investigated the influence of gaze by manipulating mutual eye contact. Therefore, gaze and body direction have been changed as a whole, resulting in only congruent gaze and body directions (averted or directed) of another person. Here, we aimed to disentangle these effects by using short animated sequences of virtual agents posing with either direct or averted body or gaze. Attention allocation by means of eye movements, facial muscle response, and emotional experience to agents of different gender and facial expressions were investigated. Eye movement data revealed longer fixation durations, i.e., a stronger allocation of attention, when gaze and body direction were not congruent with each other or when both were directed towards the observer. This suggests that direct interaction as well as incongruous signals increase the demands of attentional resources in the observer. For the facial muscle response, only the reaction of muscle zygomaticus major revealed an effect of body direction, expressed by stronger activity in response to happy expressions for direct compared to averted gaze when the virtual character's body was directed towards the observer. Finally, body direction also influenced the emotional experience ratings towards happy expressions. While earlier findings suggested that mutual eye contact is the main source for increased emotional responding and attentional allocation, the present results indicate that direction of the virtual agent's body and head also plays a minor but significant role. PMID:26004021

  17. High spatial resolution infrared imaging of L1551-IRS 5 - Direct observations of its circumstellar envelope

    NASA Technical Reports Server (NTRS)

    Moneti, Andrea; Forrest, William J.; Pipher, Judith L.; Woodward, Charles E.

    1988-01-01

    Images of L1551-IRS 5 were obtained at 1.65, 2.2, and 3.8 microns using the University of Rochester's Infrared Array Camera. It is found that IRS 5 is spatially resolved, and that it is elongated: the observed FWHM size of IRS 5 is 4.1 x 2.8 arcsec-squared at 2.2 microns. These observations are interpreted in terms of a flattened circumstellar envelope that is viewed from about 18 deg above its equatorial plane, a configuration that has been treated theoretically by Lefevre et al. In this model the central star is not seen directly, but only light scattered toward the observer from the visible polar region, where the envelope is thinnest, is observed. It is deduced that the envelope has a diameter of 1000 AU, a molecular hydrogen density of greater than or approximately equal to 4 x 10 to the 6th/cu cm, and a mass of greater than or approximately equal to 0.02 M solar mass, which results in an extinction of Av greater than about 33 mag to the central source.

  18. Direct estimation of tidally induced Earth rotation variations observed by VLBI

    NASA Astrophysics Data System (ADS)

    Englich, S.; Heinkelmann, R.; BOHM, J.; Schuh, H.

    2009-09-01

    The subject of our study is the investigation of periodical variations induced by solid Earth tides and ocean tides in Earth rotation parameters (ERP: polar motion, UT1)observed by VLBI. There are two strategies to determine the amplitudes and phases of Earth rotation variations from observations of space geodetic techniques. The common way is to derive time series of Earth rotation parameters first and to estimate amplitudes and phases in a second step. Results obtained by this means were shown in previous studies for zonal tidal variations (Englich et al.; 2008a) and variations caused by ocean tides (Englich et al.; 2008b). The alternative method is to estimate the tidal parameters directly within the VLBI data analysis procedure together with other parameters such as station coordinates, tropospheric delays, clocks etc. The purpose of this work was the application of this direct method to a combined VLBI data analysis using the software packages OCCAM (Version 6.1, Gauss-Markov-Model) and DOGSCS (Gerstl et al.; 2001). The theoretical basis and the preparatory steps for the implementation of this approach are presented here.

  19. The Exozodiacal Dust Problem for Direct Observations of Exo-Earths

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

    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 system''s 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 article, we qualitatively assess the primary impact of exozodiacal 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 article represents the first report of NASA''s Exoplanet Exploration Program Analysis Group (ExoPAG).

  20. Polarization and direction of arrival of Jovian quasiperiodic bursts observed by Cassini

    NASA Astrophysics Data System (ADS)

    Kimura, T.; Cecconi, B.; Zarka, P.; Kasaba, Y.; Tsuchiya, F.; Misawa, H.; Morioka, A.

    2012-11-01

    Jovian quasiperiodic (QP) radio bursts are suspected to be associated with relativistic particle accelerations occurring with a quasiperiodicity between a few minutes and a few tens of minutes in Jupiter's polar magnetosphere. Understanding the excitation and propagation of QP bursts could help us to better understand this periodic energization process. A first necessary step is to measure the wave mode, source location, and directivity of QP bursts. For that purpose, we performed a statistical analysis of goniopolarimetric measurements of QP bursts made with the Radio and Plasma Wave Science investigation (RPWS) onboard Cassini spacecraft during the Jupiter flyby of 2000-2001. We studied two groups of QP bursts on 22 and 23 December 2000, and we found consistent source directions about 50 RJ north of Jupiter with an error bar ?20 RJ. Statistics of the Stokes parameters indicate that QP bursts are partially left-handed polarized (V > 0, Q, U < 0). Together with the direction finding results, these polarization statistics imply that QP bursts observed from low latitudes are L-O mode waves which have been excited in the northern polar source, have propagated toward high latitudes, and then got refracted equatorward in the magnetosheath. Dependence of the Stokes parameters on the longitude indicates that QP bursts are excited within a particular phase range of the planetary rotation, when the system III longitude of the sub-solar point is between 260° and 480°. This implies that QP radio bursts and associated particle accelerations always occur within the same rotational sector, suggesting the existence of a recurrent magnetospheric disturbance at the planetary rotation period. Finally, we propose a possible scenario for the generation and propagation of QP bursts by combining the results of the present study with those of other recent observational and theoretical studies.

  1. Direct in situ observation of synergism between cellulolytic enzymes during the biodegradation of crystalline cellulose fibers.

    PubMed

    Wang, Jingpeng; Quirk, Amanda; Lipkowski, Jacek; Dutcher, John R; Clarke, Anthony J

    2013-12-01

    High-resolution atomic force microscopy (AFM) was used to image the real-time in situ degradation of crystalline by three types of T. reesei cellulolytic enzymes-TrCel6A, TrCel7A, and TrCel7B-and their mixtures. TrCel6A and TrCel7A are exo-acting cellobiohydrolases processing cellulose fibers from the nonreducing and reducing ends, respectively. TrCel7B is an endoglucanase that hydrolyzes amorphous cellulose within fibers. When acting alone on native cellulose fibers, each of the three enzymes is incapable of significant degradation. However, mixtures of two enzymes exhibited synergistic effects. The degradation effects of this synergism depended on the order in which the enzymes were added. Faster hydrolysis rates were observed when TrCel7A (exo) was added to fibers pretreated first with TrCel7B (endo) than when adding the enzymes in the opposite order. Endo-acting TrCel7B removed amorphous cellulose, softened and swelled the fibers, and exposed single microfibrils, facilitating the attack by the exo-acting enzymes. AFM images revealed that exo-acting enzymes processed the TrCel7B-pretreated fibers preferentially from one specific end (reducing or nonreducing). The most efficient (almost 100%) hydrolysis was observed with the mixture of the three enzymes. In this mixture, TrCel7B softened the fiber and TrCel6A and TrCel7A were directly observed to process it from the two opposing ends. This study provides high-resolution direct visualization of the nature of the synergistic relation between T. reesei exo- and endo-acting enzymes digesting native crystalline cellulose. PMID:24195649

  2. Deadbeat flux level control of direct-field-oriented high-horsepower induction servo motor using adaptive rotor flux observer

    Microsoft Academic Search

    Lipei Huang; Yasuki Tadokoro; Kouki Matsuse

    1994-01-01

    A method for the deadbeat flux level control of direct-field-oriented high-power induction servo motor drives has been developed that employs an adaptive rotor flux observer. The observer is a full-order type and is used not only in the direct-field-oriented controller, but also to determine the stator and rotor resistances of the servo motor. The observer reduces the sensitivity of a

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

  4. Direct observations of the influence of solution composition on magnesite dissolution

    NASA Astrophysics Data System (ADS)

    King, Helen E.; Putnis, Christine V.

    2013-05-01

    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.

  5. Direct probes of Dark Matter in the cluster 1ES0657-556 through microwave observations

    E-print Network

    Colafrancesco, S; Masi, S; Polenta, G; Ullio, P

    2007-01-01

    The cluster 1ES0657-556 is an ideal astrophysical laboratory to study the distribution and the nature of Dark Matter because this last component is spatially separated from the intracluster gas. We show that microwave observations can provide crucial probes of Dark Matter in this system. We calculate the expected SZ effect from Dark Matter annihilation in the main mass concentrations of the cluster 1ES0657-556, and we estimate the sources of contamination, confusion and bias to asses its significance. We find that SZ observations at a frequency of 223 GHz can resolve both spatially and spectrally the SZ_DM signal and isolate it from the other SZ signals, and mainly from the thermal SZ effect which is null at frequencies 220-223 GHz for the case of 1ES0657-556. We conclude that SZ observations with sub-arcmin resolution and micro-K sensitivity of 1ES0657-556 are crucial, and maybe unique, to find direct astrophysical probes of the existence and of the nature of Dark Matter, or to set strong experimental limits...

  6. Direct observation of hole transfer from semiconducting polymer to carbon nanotubes.

    PubMed

    Lan, Fei; Li, Guangyong

    2013-05-01

    Carbon nanotubes have been proven to play significant roles in polymer-based solar cells. However, there is intensive debate on whether carbon nanotube behaves as a donor or acceptor in the semiconducting polymer:carbon nanotube composite. In this paper, we report a direct observation via Kelvin probe force microscopy (KPFM) that single walled carbon nanotubes (SWNTs) behave as hole transporting channels in poly(3-hexylthiophene-2,5-diyl) (P3HT)/SWNT heterojunctions. By comparing the surface potential (SP) change of SWNT in dark and under illumination, we observed that electrons are blocked from SWNT while holes are transferred to SWNT. This observation can be well-explained by our proposed band alignment model of P3HT/SWNT heterojunction. The finding is further verified by hole mobility measurement using the space charge limited current (SCLC) method. SCLC results indicate that the existence of small amount of SWNT (wt 0.5%) promotes device hole mobility to around 15-fold, indicating SWNT act as hole transfer channel. Our finding of hole transporting behavior of SWNT in P3HT/SWNT blend will provide a useful guidance for enhancing the performance of polymer solar cells by carbon nanotubes. PMID:23574570

  7. Chemotaxis study using optical tweezers to observe the strength and directionality of forces of Leishmania amazonensis

    NASA Astrophysics Data System (ADS)

    Pozzo, Liliana d. Y.; Fontes, Adriana; de Thomaz, André A.; Barbosa, Luiz C.; Ayres, Diana C.; Giorgio, Selma; Cesar, Carlos L.

    2006-08-01

    The displacements of a dielectric microspheres trapped by an optical tweezers (OT) can be used as a force transducer for mechanical measurements in life sciences. This system can measure forces on the 50 femto Newtons to 200 pico Newtons range, of the same order of magnitude of a typical forces induced by flagellar motion. The process in which living microorganisms search for food and run away from poison chemicals is known is chemotaxy. Optical tweezers can be used to obtain a better understanding of chemotaxy by observing the force response of the microorganism when placed in a gradient of attractors and or repelling chemicals. This report shows such observations for the protozoa Leishmania amazomenzis, responsible for the leishmaniasis, a serious tropical disease. We used a quadrant detector to monitor the movement of the protozoa for different chemicals gradient. This way we have been able to observe both the force strength and its directionality. The characterization of the chemotaxis of these parasites can help to understand the infection mechanics and improve the diagnosis and the treatments employed for this disease.

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

    PubMed Central

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

    2006-01-01

    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 into mainstream health care practices for tic disorders (e.g., psychiatry and neurology), the use of direct observation as a primary assessment tool has been neglected in favor of less objective methods. Hesitation to use direct observation appears to stem largely from concerns about the generalizability of clinic observations to other settings (e.g., home) and a lack of consensus regarding the most appropriate and feasible techniques for conducting and scoring direct observation. The purpose of the current study was to evaluate and establish a reliable, valid, and feasible direct-observation protocol capable of being transported to research and clinical settings. A total of 43 children with tic disorders, collected from two outpatient specialty clinics, were assessed using direct (videotape samples) and indirect (Yale Global Tic Severity Scale; YGTSS) methods. Videotaped observation samples were collected across 3 consecutive weeks and two different settings (clinic and home), were scored using both exact frequency counts and partial-interval coding, and were compared to data from a common indirect measure of tic severity (the YGTSS). In addition, various lengths of videotaped segments were scored to determine the optimal observation length. Results show that (a) clinic-based observations correspond well to home-based observations, (b) brief direct-observation segments scored with time-sampling methods reliably quantified tics, and (c) indirect methods did not consistently correspond with the direct methods. PMID:17236340

  9. THE EFFECTIVENESS OF CLOSED CIRCUIT TELEVISION OBSERVATION AND OF DIRECT OBSERVATION OF CHILDREN'S ART CLASSES FOR IMPLEMENTING ELEMENTARY TEACHERS' TRAINING IN ART EDUCATION.

    ERIC Educational Resources Information Center

    SYKES, RONALD E.

    AN EXPERIMENTAL STUDY WAS DESIGNED TO MEASURE THE EXTENT TO WHICH CLOSED CIRCUIT TELEVISION OBSERVATIONS AND DIRECT OBSERVATIONS OF CHILDREN'S ART CLASSES CONTRIBUTE SIGNIFICANTLY TO THE ABILITY OF ELEMENTARY EDUCATION MAJORS TO DISCRIMINATE BETWEEN DESIRABLE AND UNDESIRABLE SOLUTIONS TYPICALLY OCCURRING IN TEACHING ART TO ELEMENTARY SCHOOL…

  10. Effects of action observation on corticospinal excitability: Muscle specificity, direction, and timing of the mirror response.

    PubMed

    Naish, Katherine R; Houston-Price, Carmel; Bremner, Andrew J; Holmes, Nicholas P

    2014-10-01

    Many human behaviours and pathologies have been attributed to the putative mirror neuron system, a neural system that is active during both the observation and execution of actions. While there are now a very large number of papers on the mirror neuron system, variations in the methods and analyses employed by researchers mean that the basic characteristics of the mirror response are not clear. This review focuses on three important aspects of the mirror response, as measured by modulations in corticospinal excitability: (1) muscle specificity; (2) direction; and (3) timing of modulation. We focus mainly on electromyographic (EMG) data gathered following single-pulse transcranial magnetic stimulation (TMS), because this method provides precise information regarding these three aspects of the response. Data from paired-pulse TMS paradigms and peripheral nerve stimulation (PNS) are also considered when we discuss the possible mechanisms underlying the mirror response. In this systematic review of the literature, we examine the findings of 85 TMS and PNS studies of the human mirror response, and consider the limitations and advantages of the different methodological approaches these have adopted in relation to discrepancies between their findings. We conclude by proposing a testable model of how action observation modulates corticospinal excitability in humans. Specifically, we propose that action observation elicits an early, non-specific facilitation of corticospinal excitability (at around 90ms from action onset), followed by a later modulation of activity specific to the muscles involved in the observed action (from around 200ms). Testing this model will greatly advance our understanding of the mirror mechanism and provide a more stable grounding on which to base inferences about its role in human behaviour. PMID:25281883

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

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

    PubMed Central

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

    2001-01-01

    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. PMID:11189809

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

    PubMed Central

    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

    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

  14. Direct Observation of a Gate Tunable Band Gap in Electrical Transport in ABC-Trilayer Graphene.

    PubMed

    Khodkov, Tymofiy; Khrapach, Ivan; Craciun, Monica Felicia; Russo, Saverio

    2015-07-01

    Few layer graphene systems such as Bernal stacked bilayer and rhombohedral (ABC-) stacked trilayer offer the unique possibility to open an electric field tunable energy gap. To date, this energy gap has been experimentally confirmed in optical spectroscopy. Here we report the first direct observation of the electric field tunable energy gap in electronic transport experiments on doubly gated suspended ABC-trilayer graphene. From a systematic study of the nonlinearities in current versus voltage characteristics and the temperature dependence of the conductivity, we demonstrate that thermally activated transport over the energy-gap dominates the electrical response of these transistors. The estimated values for energy gap from the temperature dependence and from the current voltage characteristics follow the theoretically expected electric field dependence with critical exponent 3/2. These experiments indicate that high quality few-layer graphene are suitable candidates for exploring novel tunable terahertz light sources and detectors. PMID:26079989

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

    PubMed

    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

    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 (93(-11)(+7)) % 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

  16. Direct Observation of Sulfur Radicals as Reaction Media in Lithium Sulfur Batteries

    DOE PAGESBeta

    Wang, Qiang; Zheng, Jianming; Walter, Eric; Pan, Huilin; Lv, Dongping; Zuo, Pengjian; Chen, Honghao; Deng, Z. D.; Liaw, Bor Y.; Yu, Xiqian; et al

    2014-12-09

    Lithium sulfur (Li-S) battery has been regaining tremendous interest in recent years because of its attractive attributes such as high gravimetric energy, low cost and environmental benignity. However, it is still not conclusively known how polysulfide ring/chain participates in the whole cycling and whether the discharge and charge processes follow the same pathway. Herein, we demonstrate the direct observation of sulfur radicals by using in situ electron paramagnetic resonance (EPR) technique. Based on the concentration changes of sulfur radicals at different potentials and the electrochemical characteristics of the cell, it is revealed that the chemical and electrochemical reactions in Li-Smore »cell are driving each other to proceed through sulfur radicals, leading to two completely different reaction pathways during discharge and charge. The proposed radical mechanism may provide new perspectives to investigate the interactions between sulfur species and the electrolyte, inspiring novel strategies to develop Li-S battery technology.« less

  17. Understanding the experiences of caregivers of children with tuberculosis in directly observed therapy.

    PubMed

    Silva, Thatiana de Medeiros Vale da; Santos, Maria Áurea Dos; Almeida, Fabiane de Amorim

    2014-12-01

    Objective To understand the situations and communications experienced by caregivers of children with tuberculosis (TB) with regard to directly observed therapy (DOT). Method A descriptive exploratory study with a qualitative approach was applied and developed in the ambulatory of Programa Einstein na Comunidade de Paraisópolis (PECP). The data were collected using semi-structured interviews of 13 caregivers of children with TB in DOT. The Collective Subject Discourse (CSD) method was used to analyze the data. Results Seven CSDs were identified and grouped into four categories: "Living in a difficult situation", "Changing the family routine", "Responsibility almost always fall son the mother", and "Adapting to the DOT". Conclusions The difficulties faced by the caregiver of the child at the beginning of DOT significantly changed the familiar routine. The responsibility for its continuity was assigned to the mother, who must adapt to the demands of the treatment and face the situation. PMID:25830734

  18. Direct Observation of Ion Distributions near Electrodes in Ionic Polymer Actuators Containing Ionic Liquids

    PubMed Central

    Liu, Yang; Lu, Caiyan; Twigg, Stephen; Ghaffari, Mehdi; Lin, Junhong; Winograd, Nicholas; Zhang, Q. M.

    2013-01-01

    The recent boom of energy storage and conversion devices, exploiting ionic liquids (ILs) to enhance the performance, requires an in-depth understanding of this new class of electrolytes in device operation conditions. One central question critical to device performance is how the mobile ions accumulate near charged electrodes. Here, we present the excess ion depth profiles of ILs in ionomer membrane actuators (Aquivion/1-butyl-2,3-dimethylimidazolium chloride (BMMI-Cl), 27??m thick), characterized directly by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) at liquid nitrogen temperature. Experimental results reveal that for the IL studied, cations and anions are accumulated at both electrodes. The large difference in the total volume occupied by the excess ions between the two electrodes cause the observed large bending actuation of the actuator. Hence we demonstrate that ToF-SIMS experiment provides great insights on the physics nature of ionic devices. PMID:23512124

  19. Direct observation of rare-earth ions in ?-sialon:Ce phosphors.

    PubMed

    Xu, Fangfang; Sourty, Erwan; Shi, Wei; Mou, Xinliang; Zhang, Linlin

    2011-04-01

    Doping structures of Ce(3+) into the refractory ?-sialon crystal lattice have been examined via an atom-resolved Cs-corrected scanning transmission electron microscope. The location and coordination of the rare-earth ions are well-defined through direct observation in conjunction with structural modeling and image simulation. The stability and solubility of Ce(3+) ions could be remarkably enhanced via congregation into the planar defects formed by a 1/3 (210)-type lattice displacement along with an inversion operation. The formation of cylindrical chambers near the defects is believed to provide effective structural relaxation upon doping of large rare-earth ions into the interstices in their neighborhoods. The as-revealed structural information could be useful for understanding the luminescence properties of the promising rare-earth doped sialon materials. PMID:21370828

  20. Direct Observation of Sulfur Radicals as Reaction Media in lithium Sulfur Batteries

    SciTech Connect

    Wang, Qiang; Zheng, Jianming; Walter, Eric D.; Pan, Huilin; Lu, Dongping; Zuo, Pengjian; Chen, Honghao; Deng, Zhiqun; Liaw, Bor Yann; Yu, Xiqian; Yang, Xiaoning; Zhang, Jiguang; Liu, Jun; Xiao, Jie

    2014-12-09

    Lithium sulfur (Li-S) battery has been regaining tremendous interest in recent years because of its attractive attributes such as high gravimetric energy, low cost and environmental benignity. However, it is still not conclusively known how polysulfide ring/chain participates in the whole cycling and whether the discharge and charge process follow the same pathway. Herein, we demonstrate the direct observation of sulfur radicals by using in situ electron paramagnetic resonance (EPR) technique. Based on the concentration changes of sulfur radicals at different potentials, it is revealed that the chemical and electrochemical reactions in Li-S cell are driven each other to proceed through sulfur radicals, leading to two completely different reaction pathways during discharge and charge. The proposed radical mechanism may provide new insights to investigate the interactions between sulfur species and the electrolyte, inspiring novel strategies to develop Li-S battery technology.

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

    PubMed Central

    Kovalev, Alexander E; Gorb, Stanislav N

    2014-01-01

    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. PMID:24991528

  2. Direct observation of graphene growth and associated copper substrate dynamics by in situ scanning electron microscopy.

    PubMed

    Wang, Zhu-Jun; Weinberg, Gisela; Zhang, Qiang; Lunkenbein, Thomas; Klein-Hoffmann, Achim; Kurnatowska, Michalina; Plodinec, Milivoj; Li, Qing; Chi, Lifeng; Schloegl, R; Willinger, Marc-Georg

    2015-02-24

    This work highlights the importance of in situ experiments for an improved understanding of graphene growth on copper via metal-catalyzed chemical vapor deposition (CVD). Graphene growth inside the chamber of a modified environmental scanning electron microscope under relevant low-pressure CVD conditions allows visualizing structural dynamics of the active catalyst simultaneously with graphene nucleation and growth in an unparalleled way. It enables the observation of a complete CVD process from substrate annealing through graphene nucleation and growth and, finally, substrate cooling in real time and nanometer-scale resolution without the need of sample transfer. A strong dependence of surface dynamics such as sublimation and surface premelting on grain orientation is demonstrated, and the influence of substrate dynamics on graphene nucleation and growth is presented. Insights on the growth mechanism are provided by a simultaneous observation of the growth front propagation and nucleation rate. Furthermore, the role of trace amounts of oxygen during growth is discussed and related to graphene-induced surface reconstructions during cooling. Above all, this work demonstrates the potential of the method for in situ studies of surface dynamics on active metal catalysts. PMID:25584770

  3. Direct single-molecule observation of calcium-dependent misfolding in human neuronal calcium sensor-1

    PubMed Central

    Heidarsson, Pétur O.; Naqvi, Mohsin M.; Otazo, Mariela R.; Mossa, Alessandro; Kragelund, Birthe B.; Cecconi, Ciro

    2014-01-01

    Neurodegenerative disorders are strongly linked to protein misfolding, and crucial to their explication is a detailed understanding of the underlying structural rearrangements and pathways that govern the formation of misfolded states. Here we use single-molecule optical tweezers to monitor misfolding reactions of the human neuronal calcium sensor-1, a multispecific EF-hand protein involved in neurotransmitter release and linked to severe neurological diseases. We directly observed two misfolding trajectories leading to distinct kinetically trapped misfolded conformations. Both trajectories originate from an on-pathway intermediate state and compete with native folding in a calcium-dependent manner. The relative probability of the different trajectories could be affected by modulating the relaxation rate of applied force, demonstrating an unprecedented real-time control over the free-energy landscape of a protein. Constant-force experiments in combination with hidden Markov analysis revealed the free-energy landscape of the misfolding transitions under both physiological and pathological calcium concentrations. Remarkably for a calcium sensor, we found that higher calcium concentrations increased the lifetimes of the misfolded conformations, slowing productive folding to the native state. We propose a rugged, multidimensional energy landscape for neuronal calcium sensor-1 and speculate on a direct link between protein misfolding and calcium dysregulation that could play a role in neurodegeneration. PMID:25157171

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

    PubMed

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

    1999-01-19

    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

  5. The Exozodiacal Dust Problem for Direct Observations of ExoEarths

    E-print Network

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

    2012-01-01

    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 System's 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 detec...

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    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.

  7. Direct observation of the hole protonation state and hole localization site in DNA-oligomers

    PubMed Central

    Adhikary, Amitava; Khanduri, Deepti; Sevilla, Michael D.

    2009-01-01

    In this work, it is shown that the incorporation of an 8-deuteroguanine (G*) moiety in DNA-oligomers allows for direct determination at 77 K of (i) the location of holes (i.e., the radical site) within dsDNA at specific base sites, even within stacks of G, as well as (ii) the protonation state of the hole at that site. These findings are based on our work and demonstrate that selective deuteration at C-8 on guanine moiety in dGuo results in an ESR signal from the guanine cation radical (G*•+) which is easily distinguishable from that of the undeuterated guanine cation radical (G•+). G*•+ is also found to be easily distinguishable from its conjugate base, the N1-deprotonated radical, G*(?H)•. Our ESR results clearly establish that at 77 K (i) one-electron oxidized guanine in double stranded DNA-oligomers exists as the deprotonated neutral radical G(?H)• as a result of facile proton transfer to the hydrogen bonded cytosine, and (ii) the hole is preferentially located at the 5?-end in several ds DNA-oligomers with a GGG sequence. PMID:19469533

  8. Direct observation of interfacial Au atoms on TiO? in three dimensions.

    PubMed

    Gao, Wenpei; Sivaramakrishnan, Shankar; Wen, Jianguo; Zuo, Jian-Min

    2015-04-01

    Interfacial atoms, which result from interactions between the metal nanoparticles and support, have a large impact on the physical and chemical properties of nanoparticles. However, they are difficult to observe; the lack of knowledge has been a major obstacle toward unraveling their role in chemical transformations. Here we report conclusive evidence of interfacial Au atoms formed on the rutile (TiO2) (110) surfaces by activation using high-temperature (?500 °C) annealing in air. Three-dimensional imaging was performed using depth-sectioning enabled by aberration-corrected scanning transmission electron microscopy. Results show that the interface between Au nanocrystals and TiO2 (110) surfaces consists of a single atomic layer with Au atoms embedded inside Ti-O. The number of interfacial Au atoms is estimated from ?1-8 in an interfacial atomic column. Direct impact of interfacial Au atoms is observed on an enhanced Au-TiO2 interaction and the reduction of surface TiO2; both are critical to Au catalysis. PMID:25761226

  9. Direct observations of evolving subglacial drainage beneath the Greenland Ice Sheet.

    PubMed

    Andrews, Lauren C; Catania, Ginny A; Hoffman, Matthew J; Gulley, Jason D; Lüthi, Martin P; Ryser, Claudia; Hawley, Robert L; Neumann, Thomas A

    2014-10-01

    Seasonal acceleration of the Greenland Ice Sheet is influenced by the dynamic response of the subglacial hydrologic system to variability in meltwater delivery to the bed via crevasses and moulins (vertical conduits connecting supraglacial water to the bed of the ice sheet). As the melt season progresses, the subglacial hydrologic system drains supraglacial meltwater more efficiently, decreasing basal water pressure and moderating the ice velocity response to surface melting. However, limited direct observations of subglacial water pressure mean that the spatiotemporal evolution of the subglacial hydrologic system remains poorly understood. Here we show that ice velocity is well correlated with moulin hydraulic head but is out of phase with that of nearby (0.3-2 kilometres away) boreholes, indicating that moulins connect to an efficient, channelized component of the subglacial hydrologic system, which exerts the primary control on diurnal and multi-day changes in ice velocity. Our simultaneous measurements of moulin and borehole hydraulic head and ice velocity in the Paakitsoq region of western Greenland show that decreasing trends in ice velocity during the latter part of the melt season cannot be explained by changes in the ability of moulin-connected channels to convey supraglacial melt. Instead, these observations suggest that decreasing late-season ice velocity may be caused by changes in connectivity in unchannelized regions of the subglacial hydrologic system. Understanding this spatiotemporal variability in subglacial pressures is increasingly important because melt-season dynamics affect ice velocity beyond the conclusion of the melt season. PMID:25279921

  10. Magnetic fields in the Venus ionosphere: Dependence on the IMF direction—Venus express observations

    NASA Astrophysics Data System (ADS)

    Dubinin, E.; Fraenz, M.; Zhang, T. L.; Woch, J.; Wei, Y.

    2014-09-01

    The structure of the magnetized ionosphere of Venus is investigated using the magnetometer and plasma (Analyzer of Space Plasmas and Energetic Atoms 4) data from the Venus Express spacecraft. Observations surveying the low-altitude (h ? 250 km) ionosphere were made at solar zenith angles ? 75°. The magnetic field permeating the Venus ionosphere at solar minimum conditions increases at low altitudes and reaches a maximum at an altitude of ˜200 km. The orientation of the magnetic field in the peak is almost insensible to the magnetic field direction in the solar wind. For both sector polarities of the IMF, the magnetic field vector has a dominant dawn-dusk component. The topology of the magnetic field also occurs different for different signs of the cross-flow component of the IMF revealing either a sudden straightening with liberation of the magnetic field stresses or a closing into a loop. We discuss different mechanisms of the peak formation including local magnetization, a weak intrinsic planetary field, a dipole field induced by eddy currents, a remnant origin, or giant flux ropes. All of them fail to explain most of the observed features. We suggest that a decoupling of ion and electron motion at low altitudes due to ion-neutral collisions results in currents which produce different field configurations depending on the IMF orientation.

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Heinemann, K.; Poppa, H.

    1975-01-01

    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.

  13. Influence of Observed Diurnal Cycles of Aerosol Optical Depth on Aerosol Direct Radiative Effect

    NASA Technical Reports Server (NTRS)

    Arola, A.; Eck, T. F.; Huttunen, J.; Lehtinen, K. E. J.; Lindfors, A. V.; Myhre, G.; Smirinov, A.; Tripathi, S. N.; Yu, H.

    2013-01-01

    The diurnal variability of aerosol optical depth (AOD) can be significant, depending on location and dominant aerosol type. However, these diurnal cycles have rarely been taken into account in measurement-based estimates of aerosol direct radiative forcing (ADRF) or aerosol direct radiative effect (ADRE). The objective of our study was to estimate the influence of diurnal aerosol variability at the top of the atmosphere ADRE estimates. By including all the possible AERONET sites, we wanted to assess the influence on global ADRE estimates. While focusing also in more detail on some selected sites of strongest impact, our goal was to also see the possible impact regionally.We calculated ADRE with different assumptions about the daily AOD variability: taking the observed daily AOD cycle into account and assuming diurnally constant AOD. Moreover, we estimated the corresponding differences in ADREs, if the single AOD value for the daily mean was taken from the the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra or Aqua overpass times, instead of accounting for the true observed daily variability. The mean impact of diurnal AOD variability on 24 h ADRE estimates, averaged over all AERONET sites, was rather small and it was relatively small even for the cases when AOD was chosen to correspond to the Terra or Aqua overpass time. This was true on average over all AERONET sites, while clearly there can be much stronger impact in individual sites. Examples of some selected sites demonstrated that the strongest observed AOD variability (the strongest morning afternoon contrast) does not typically result in a significant impact on 24 h ADRE. In those cases, the morning and afternoon AOD patterns are opposite and thus the impact on 24 h ADRE, when integrated over all solar zenith angles, is reduced. The most significant effect on daily ADRE was induced by AOD cycles with either maximum or minimum AOD close to local noon. In these cases, the impact on 24 h ADRE was typically around 0.1-0.2W/sq m (both positive and negative) in absolute values, 5-10% in relative ones.

  14. In Situ Observation of Directed Nanoparticle Aggregation During the Synthesis of Ordered Nanoporous Metal in Soft Templates

    SciTech Connect

    Parent, Lucas R.; Robinson, David B.; Cappillino, Patrick J.; Hartnett, Ryan J.; Abellan Baeza, Patricia; Evans, James E.; Browning, Nigel D.; Arslan, Ilke

    2014-02-11

    The prevalent approach to developing new nanomaterials is a trial and error process of iteratively altering synthesis procedures and then characterizing the resulting nanostructures. This is fundamentally limited in that the growth processes that occur during synthesis can only be inferred from the final synthetic structure. Directly observing real-time nanomaterial growth provides unprecedented insight into the relationship between synthesis conditions and product evolution, and facilitates a mechanistic approach to nanomaterial development. Here we use in situ liquid stage scanning transmission electron microscopy to observe the growth of mesoporous palladium in a solvated block copolymer (BCP) template under various synthesis conditions, and ultimately determine a refined synthesis procedure that yields ordered pores. We find that at low organic solvent (tetrahydrofuran, THF) content, the BCP assembles into a rigid, cylindrical micelle array with a high degree of short-range order, but poor long-range order. Upon slowing the THF evaporation rate using a solvent-vapor anneal step, the long-range order is greatly improved. The electron beam induces nucleation of small particles in the aqueous phase around the micelles. The small particles then flocculate and grow into denser structures that surround the micelles, forming an ordered mesoporous structure. The microscope observations revealed that template disorder can be addressed prior to reaction, and is not invariably induced by the growth process itself, allowing us to more quickly optimize the synthetic method. This work was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy under contract DE-AC05-76RL01830. This research was funded in part by: the Presidential Early Career Award for Scientist and Engineers for I.A., the University of California Academic Senate and the University of California Laboratory fee research grant, the Laboratory-Directed Research and Development program at Sandia National Laboratories, and the Chemical Imaging Initiative at Pacific Northwest National Laboratory. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  15. Direct Observations of Rapid Diffusion of Cu in Au Thin Films using In-Situ X-ray Diffraction

    SciTech Connect

    Elmer, J W; Palmer, T A; Specht, E D

    2005-11-28

    In-situ x-ray diffraction was performed while annealing thin-film Au/Cu binary diffusion couples to directly observe diffusion at elevated temperatures. The temperature dependence of the interdiffusion coefficient was determined from isothermal measurements at 700 C, 800 C, and 900 C, where Cu and Au form a disordered continuous face centered cubic solid solution. Large differences in the lattice parameters of Au and Cu allowed the initial diffraction peaks to be easily identified, and later tracked as they merged into one diffraction peak with increased diffusion time. Initial diffusion kinetics were studied by measuring the time required for the Cu to diffuse through the Au thin film of known thickness. The activation energy for interdiffusion was measured to be 65.4 kJ/mole during this initial stage, which is approximately 0.4x that for bulk diffusion and 0.8x that for grain boundary diffusion. The low activation energy is attributed to the high density of columnar grain boundaries combined with other defects in the sputter deposited thin film coatings. As interdiffusion continues, the two layers homogenize with an activation energy of 111 kJ/mole during the latter stages of diffusion. This higher activation energy falls between the reported values for grain boundary and bulk diffusion, and may be related to grain growth occurring at these temperatures which accounts for the decreasing importance of grain boundaries on diffusion.

  16. Constraining nova observables: Direct measurements of resonance strengths in 33S(p,?)34Cl

    NASA Astrophysics Data System (ADS)

    Fallis, J.; Parikh, A.; Bertone, P. F.; Bishop, S.; Buchmann, L.; Chen, A. A.; Christian, G.; Clark, J. A.; D'Auria, J. M.; Davids, B.; Deibel, C. M.; Fulton, B. R.; Greife, U.; Guo, B.; Hager, U.; Herlitzius, C.; Hutcheon, D. A.; José, J.; Laird, A. M.; Li, E. T.; Li, Z. H.; Lian, G.; Liu, W. P.; Martin, L.; Nelson, K.; Ottewell, D.; Parker, P. D.; Reeve, S.; Rojas, A.; Ruiz, C.; Setoodehnia, K.; Sjue, S.; Vockenhuber, C.; Wang, Y. B.; Wrede, C.

    2013-10-01

    The 33S(p,?)34Cl reaction is important for constraining predictions of certain isotopic abundances in oxygen-neon novae. Models currently predict as much as 150 times the solar abundance of 33S in oxygen-neon nova ejecta. This overproduction factor may vary by orders of magnitude due to uncertainties in the 33S(p,?)34Cl reaction rate at nova peak temperatures. Depending on this rate, 33S could potentially be used as a diagnostic tool for classifying certain types of presolar grains. Better knowledge of the 33S(p,?)34Cl rate would also aid in interpreting nova observations over the S-Ca mass region and contribute to the firm establishment of the maximum endpoint of nova nucleosynthesis. Additionally, the total S elemental abundance which is affected by this reaction has been proposed as a thermometer to study the peak temperatures of novae. Previously, the 33S(p,?)34Cl reaction rate had only been studied directly down to resonance energies of 432 keV. However, for nova peak temperatures of 0.2-0.4 GK there are seven known states in 34Cl both below the 432-keV resonance and within the Gamow window that could play a dominant role. Direct measurements of the resonance strengths of these states were performed using the DRAGON (Detector of Recoils And Gammas of Nuclear reactions) recoil separator at TRIUMF. Additionally two new states within this energy region are reported. Several hydrodynamic simulations have been performed, using all available experimental information for the 33S(p,?)34Cl rate, to explore the impact of the remaining uncertainty in this rate on nucleosynthesis in nova explosions. These calculations give a range of ?20-150 for the expected 33S overproduction factor, and a range of ?100-450 for the 32S/33S ratio expected in ONe novae.

  17. Class I Methanol Maser Observations at 44 GHz in the Direction of some SNRs and SFRs.

    NASA Astrophysics Data System (ADS)

    Larionov, G. M.; Litovchenko, I. D.; Val'tts, I. E., Alakoz, A. V.

    2011-05-01

    The results of searching for class I methanol maser emission in the interstellar medium are presented. Observations at Onsala 20-m radio telescope at 44 GHz in methanol transition 7_0-6_1A has been conducted in the direction of different types of objects of the northern hemisphere: in a little-studied region of maser emission G27.4-0.2, in some supernova remnants, in high mass protostars regions, in the dust rings around HII regions and in protostellar candidates associated with powerful bipolar outflows. In the source G27.4-0.2, which is identified with two SNR well known G27.4 +0.0 (Kes73) and possible G27.3-0.2 - class I methanol maser emission was detected at the frequency of 44 GHz. In the vicinity of the maser a map of size (27 'x 27') has been obtained. It was shown that emission at 44 GHz is formed only within the previously known maser region at 95 GHz. In four supernova remnants class I methanol maser emission was not detected at the coordinates of satellite OH (1720) maser emission. In the direction of high mass star-forming regions 9 new class I methanol masers were detected at 44 GHz. These 9 new masers are from areas characterized by high density and lack of continuum radio emission. This fact indicates the absence of ultra-compact HII regions, hence the young age of star forming regions, which have not yet formed protostar to ensure the ionization of the environment. This conclusion confirms the hypothesis of a purely collisional pumping of class I methanol masers.

  18. Direct time-resolved observation of tungsten nanostructured growth due to helium plasma exposure

    NASA Astrophysics Data System (ADS)

    Fiflis, P.; Curreli, D.; Ruzic, D. N.

    2015-03-01

    Determination of the mechanisms underlying the growth of tungsten fuzz is an important step towards mitigation of fuzz formation. Nanostructured tungsten was produced on resistively heated tungsten wires in a helicon plasma source (maximum flux of 2.5 × 1021 m?2 s?1). Asymmetry in the setup allows for investigation of temperature and flux effects in a single sample. An effort at elucidating the mechanism of formation was made by inspecting SEM micrographs of the nanostructured tungsten at successive fluence steps of helium ions up to a fluence of 1 × 1027 m?2. To create these micrographs a single tungsten sample was exposed to the plasma, removed and inspected with an SEM, and replaced into the plasma. The tungsten surface was marked in several locations so that each micrograph is centred within 200 nm of each previous micrograph. Pitting of the surface (diameter 9.5 ± 2.3 nm, fluence (5 ± 2) × 1025 m?2) followed by surface roughening (fluence (9 ± 2) × 1025 m?2) and tendril formation (diameter 30 ± 10 nm, fluence (2 ± 1) × 1026 m?2) is observed, providing evidence of bubble bursting as the mechanism for seeding the growth of the tungsten fuzz.

  19. Direct Observation of Multi-Band Physics using Quantum Phase Diffusion in 3D Optical Lattices

    NASA Astrophysics Data System (ADS)

    Will, Sebastian; Best, Thorsten; Braun, Simon; Schneider, Ulrich; Hackermüller, Lucia; Lühmann, Dirk-Sören; Bloch, Immanuel

    2009-05-01

    In recent years ultracold atoms in optical lattices have shown their potential to simulate condensed matter quantum systems. A prominent example was the realization of the superfluid to Mott insulator transition, which has theoretically been described by a single-band Bose-Hubbard model. Recent theoretical studies, however, have emphasized, that interatomic interactions may bring multi-band effects into play and considerably modify the behaviour of ultracold atomic systems. In our experiment we have trapped a BEC of ^87Rb atoms in a 3D optical lattice with minimal underlying harmonic confinement. A rapid increase of the lattice depth allows us to follow the quantum phase diffusion of the macroscopic matterwave field, showing a continuous collapse and revival, whose period is determined by the onsite interaction energy. The observed dynamics give striking evidence of multi-band physics beyond the single-band Hubbard model, our data being in excellent agreement with numerical exact diagonalization. We have extended this experimental method to tunable ^87Rb-^40K Bose-Fermi mixtures and could elucidate distinct effects of interspecies interactions.

  20. CAN-DOO: The Climate Action Network through Direct Observations and Outreach

    NASA Astrophysics Data System (ADS)

    Taubman, B.; Sherman, J. P.; Perry, L. B.; Markham, J.; Kelly, G.

    2011-12-01

    The urgency of climate change demands a greater understanding of our climate system, not only by the leaders of today, but by the scientists, policy makers, and citizens of tomorrow. Unfortunately, a large segment of the population currently possesses inadequate knowledge of climate science. In direct response to a need for greater scientific literacy with respect to climate science, researchers from Appalachian State University's Appalachian Atmospheric Interdisciplinary Research (AppalAIR) group, with support from NASA, have developed CAN-DOO: the Climate Action Network through Direct Observations and Outreach. CAN-DOO addresses climate science literacy by 1) Developing the infrastructure for sustaining and expanding public outreach through long-term climate measurements capable of complementing existing NASA measurements, 2) Enhancing public awareness of climate science and NASA's role in advancing our understanding of the Earth System, and 3) Introducing Science, Technology, Engineering, and Mathematics principles to homeschooled, public school, and Appalachian State University students through applied climate science activities. Project partners include the Grandfather Mountain Stewardship Foundation, Pisgah Astronomical Research Institute, and local elementary schools. In partnership with Grandfather Mountain, climate science awareness is promoted through citizen science activities, interactive public displays, and staff training. CAN-DOO engages students by involving them in the entire scientific investigative process as applied to climate science. We introduce local elementary and middle school students, homeschooled students throughout North Carolina, and undergraduate students in a new Global Climate Change course and select other courses at Appalachian State University to instrument assembly, measurement techniques, data collection, hypothesis testing, and drawing conclusions. Results are placed in the proper context via comparisons with other student data products, local research-grade measurements, and NASA measurements. Several educational modules have been developed that address specific topics in climate science. The modules are scalable and have been successfully implemented at levels ranging from 2nd grade through first-year graduate as well as with citizen science groups. They also can be applied in user-desired segments to a variety of Earth Science units. In this paper, we will introduce the project activities and present results from the first year of observations and outreach, with a special emphasis on two of the developed modules, the surface energy balance and aerosol optical depth module.

  1. Quantifying Aerosol Direct Effects from Broadband Irradiance and Spectral Aerosol Optical Depth Observations

    SciTech Connect

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

    2014-05-16

    We 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.

  2. Direct observation of guanine radical cation deprotonation in G-quadruplex DNA.

    PubMed

    Wu, Lidan; Liu, Kunhui; Jie, Jialong; Song, Di; Su, Hongmei

    2015-01-14

    Although numerous studies have been devoted to the charge transfer through double-stranded DNA (dsDNA), one of the major problems that hinder their potential applications in molecular electronics is the fast deprotonation of guanine cation (G(+•)) to form a neutral radical that can cause the termination of hole transfer. It is thus of critical importance to explore other DNA structures, among which G-quadruplexes are an emerging topic. By nanosecond laser flash photolysis, we report here the direct observation and findings of the unusual deprotonation behavior (loss of amino proton N2-H instead of imino proton N1-H) and slower (1-2 orders of magnitude) deprotonation rate of G(+•) within G-quadruplexes, compared to the case in the free base dG or dsDNA. Four G-quadruplexes AG3(T2AG3)3, (G4T4G4)2, (TG4T)4, and G2T2G2TGTG2T2G2 (TBA) are measured systematically to examine the relationship of deprotonation with the hydrogen-bonding surroundings. Combined with in depth kinetic isotope experiments and pKa analysis, mechanistic insights have been further achieved, showing that it should be the non-hydrogen-bonded free proton to be released during deprotonation in G-quadruplexes, which is the N2-H exposed to solvent for G bases in G-quartets or the free N1-H for G base in the loop. The slower N2-H deprotonation rate can thus ensure less interruption of the hole transfer. The unique deprotonation features observed here for G-quadruplexes open possibilities for their interesting applications as molecular electronic devices, while the elucidated mechanisms can provide illuminations for the rational design of G-quadruplex structures toward such applications and enrich the fundamental understandings of DNA radical chemistry. PMID:25506785

  3. Direct observation measurement of drowning risk exposure for surf beach bathers.

    PubMed

    Morgan, Damian; Ozanne-Smith, Joan; Triggs, Tom

    2009-07-01

    Because not all persons bathe at surf beaches, drowning rates based on resident population are likely to be underreported. To facilitate more precise drowning risk exposure data, this study aimed to develop a reliable direct observation measure of frequency and duration for surf beach bather exposure to water, by gender and age group. Bathers were defined as persons entering the water to wade, swim or surf with equipment. Observed bathers were systematically selected entering the water in daylight hours at six patrolled or unpatrolled beaches over 10 days. Variables measured were: weather and water conditions, water entries, duration of water exposure, water exposure location and person factors. The dataset comprised 204 (69.6%) males and 89 (30.4%) females, with males more likely to be in an older age group (p<0.05). Compared to females, males spent longer in the water, were more likely to use surfing equipment, and mainly used a surf zone located farther from the shore in deeper water (p<0.05). Two factors were significant predictors of bathing duration (adjusted R(2)=0.45): main surf zone occupied (based on water depth and distance from shore); and surf equipment used. The study provides new information about water exposure for bathers at surf beaches and new methods for measuring exposure to drowning risk. The findings suggest that overrepresentation of adolescent and adult males in surf beach drowning statistics is in part a product of greater total exposure to the water plus more frequent exposure to deeper water and bathing farther from shore. PMID:18768365

  4. Investigation of droplet jumping on superhydrophobic coatings during dew condensation by the observation from two directions

    NASA Astrophysics Data System (ADS)

    Yanagisawa, Kosuke; Sakai, Munetoshi; Isobe, Toshihiro; Matsushita, Sachiko; Nakajima, Akira

    2014-10-01

    Superhydrophobic coatings with nanoscale random roughness structure were prepared onto a Si substrate using boehmite (AlOOH) particles and hydrophobic silanes. The samples were cooled by a Peltier cooling element. Then spontaneous jumping behavior of the water droplets that had condensed on the coatings was observed from two directions (top-view and side-view) using high-speed camera systems. Spontaneous jumping of water droplets occurred subsequent to the coalescence of more than two water droplets, deformation, and shape recovery. Small droplets exhibited high initial jumping velocity, which decreased concomitantly with increasing difference in droplet size before coalescence. The actual jumping velocity was lower than the theoretical one, suggesting the existence of energy dissipation. When the sample was declined at 30°, the jumping frequency of water droplets fluctuated against the cooling time with repetition of the increasing-decreasing cycle, and sustained a certain value. The water droplet jumping height was increased remarkably under an external electric field. The droplet possessed positive charge. Coulombic force was expected to contribute to this phenomenon.

  5. Direct observation of solid-state reversed transformation from crystals to quasicrystals in a Mg alloy

    PubMed Central

    Liu, Jian-Fang; Yang, Zhi-Qing; Ye, Heng-Qiang

    2015-01-01

    Phase transformation of quasicrystals is of interest in various fields of science and technology. Interestingly, we directly observed unexpected solid-state epitaxial nucleation and growth of Zn 6 Mg 3 Y icosahedral quasicrystals in a Mg alloy at about 573?K which is about 300?K below the melting point of Zn 6 Mg 3 Y, in contrast to formation of quasicrystals through solidification that was usually found in many alloys. Maximizing local packing density of atoms associated with segregation of Y and Zn in Mg adjacent to Mg/Zn 3 MgY interfaces triggered atomic rearrangement in Mg to form icosahedra coupled epitaxially with surface distorted icosahedra of Zn 3 MgY, which plays a critical role in the nucleation of icosahedral clusters. A local Zn:Mg:Y ratio close to 6:3:1, corresponding to a valence electron concentration of about 2.15, should have been reached to trigger the formation of quasicrystals at Mg/Zn 3 MgY interfaces. The solid-state icosahedral ordering in crystals opens a new window for growing quasicrystals and understanding their atomic origin mechanisms. Epitaxial growth of quasicrystals onto crystals can modify the surface/interface structures and properties of crystalline materials. PMID:26066096

  6. Direct observations of nitric oxide produced by energetic electron precipitation into the Antarctic middle atmosphere

    NASA Astrophysics Data System (ADS)

    Newnham, David A.; Espy, Patrick J.; Clilverd, Mark A.; Rodger, Craig J.; Seppälä, Annika; Maxfield, David J.; Hartogh, Paul; Holmén, Kim; Horne, Richard B.

    2011-10-01

    We report the first ground-based passive microwave observations made from Troll station, Antarctica, which show enhanced mesospheric nitric oxide (NO) volume mixing ratio reaching levels of 1.2 ppmv, or 2-3 orders of magnitude above background, at 70-80 km during small, relatively isolated geomagnetic storms in 2008. The mesospheric NO peaked 2 days after enhanced NO at higher altitudes (110-150 km) measured by the SABER satellite, and 2 days after peaks in the >30 keV and >300 keV electron flux measured by POES, although the 300 keV electron flux remained high. High time resolution data shows that mesospheric NO was enhanced at night and decayed during the day and built up to high levels over a period of 3-4 days. The altitude profile of mesospheric NO suggests direct production by ˜300 keV electron precipitation. Simulations using the Sodankylä Ion and Neutral Chemistry model show that the delay between thermospheric and mesospheric NO enhancements was primarily a result of the weaker production rate at lower altitudes by ˜300 keV electrons competing against strong day-time losses.

  7. Build a better mouse: directly-observed issues in computer use for adults with SMI.

    PubMed

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

    2013-03-01

    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. PMID:22711454

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

    PubMed

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

    2012-11-27

    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

  9. Direct observation of strand passage by DNA-topoisomerase and its limited processivity.

    PubMed

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

    2012-01-01

    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. PMID:22496876

  10. Direct observation of steps in rotation of the bacterial flagellar motor.

    PubMed

    Sowa, Yoshiyuki; Rowe, Alexander D; Leake, Mark C; Yakushi, Toshiharu; Homma, Michio; Ishijima, Akihiko; Berry, Richard M

    2005-10-01

    The bacterial flagellar motor is a rotary molecular machine that rotates the helical filaments that propel many species of swimming bacteria. The rotor is a set of rings up to 45 nm in diameter in the cytoplasmic membrane; the stator contains about ten torque-generating units anchored to the cell wall at the perimeter of the rotor. The free-energy source for the motor is an inward-directed electrochemical gradient of ions across the cytoplasmic membrane, the protonmotive force or sodium-motive force for H+-driven and Na+-driven motors, respectively. Here we demonstrate a stepping motion of a Na+-driven chimaeric flagellar motor in Escherichia coli at low sodium-motive force and with controlled expression of a small number of torque-generating units. We observe 26 steps per revolution, which is consistent with the periodicity of the ring of FliG protein, the proposed site of torque generation on the rotor. Backwards steps despite the absence of the flagellar switching protein CheY indicate a small change in free energy per step, similar to that of a single ion transit. PMID:16208378

  11. Patients’ Experience of Tuberculosis Treatment Using Directly Observed Treatment, Short-Course (DOTS): A Qualitative Study

    PubMed Central

    Behzadifar, Masoud; Mirzaei, Masoud; Behzadifar, Meysam; Keshavarzi, Abouzar; Behzadifar, Maryam; Saran, Maryam

    2015-01-01

    Background: Despite effective diagnosis and treatment, prevalence of tuberculosis (TB) is still growing. The directly observed treatment, short-course (DOTS) strategy to treat TB was introduced by the World Health Organization more than a decade ago. Little is known about patients’ experience of TB treatment, according to DOTS, in Iran. Objectives: This study aimed to understand the patients’ experience of tuberculosis treatment according to DOTS in Iran. Patients and Methods: This study is a qualitative study, using content analysis to examine patients’ experience of TB treatment and to understand their compliance during DOTS. In this study, a semi-structured interview with open questions was answered by 40 patients, who had a diagnosis of pulmonary and extrapulmonary tuberculosis, and improved during the course of their treatment. The method of sampling was purposive sample and the interview process lasted until data saturation. Results: Data analysis resulted in the extraction of six themes, which reflect the experiences of the study participants. The themes are: 1) individual factors; 2) change of the attitudes and beliefs of patients on TB treatment; 3) support terms of patients with tuberculosis; 4) the role of health care professionals; 5) social factors and 6) the financial burden. Conclusions: Successful completion of TB treatment requires an effective partnership between the patient and health care professionals, and a harmony between the cultural context, attitude of the patient, family support and health literacy. Future health policies should address these issues to improve patients’ adherence to DOTS. PMID:26023334

  12. ccsd-00022730,version2-20Apr2006 Direct observation of a "devil's staircase" in wave-particle interaction

    E-print Network

    Paris-Sud XI, Université de

    ccsd-00022730,version2-20Apr2006 Direct observation of a "devil's staircase" in wave-J´er^ome, F-13397 Marseille cedex 20 We report the experimental observation of a "devil's staircase" in a time exhibits a "devil's staircase" behavior for increasing excitation amplitude, due to the nonlinear forcing

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

    SciTech Connect

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

    2007-06-01

    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.

  14. Direct Observation of Secondary Organic Aerosol Formation during Cloud Condensation-Evaporation Cycles (SOAaq) in Simulation Chamber Experiments

    NASA Astrophysics Data System (ADS)

    Doussin, J. F.; Bregonzio-Rozier, L.; Giorio, C.; Siekmann, F.; Gratien, A.; Temime-Roussel, B.; Ravier, S.; Pangui, E.; Tapparo, A.; Kalberer, M.; Monod, A.

    2014-12-01

    Biogenic volatile organic compounds (BVOCs) undergo many reactions in the atmosphere and form a wide range of oxidised and water-soluble compounds. These compounds can partition into atmospheric water droplets, and react within the aqueous phase producing higher molecular weight and/or less volatile compounds which can remain in the particle phase after water evaporation and thus increase the organic aerosol mass (Ervens et al., 2011; Altieri et al., 2008; Couvidat et al., 2013). While this hypothesis is frequently discussed in the literature, so far, almost no direct observations of such a process have been provided.The aim of the present work is to study SOA formation from isoprene photooxidation during cloud condensation-evaporation cycles.The experiments were performed during the CUMULUS project (CloUd MULtiphase chemistry of organic compoUndS in the troposphere), in the CESAM simulation chamber located at LISA. CESAM is a 4.2 m3 stainless steel chamber equipped with realistic irradiation sources and temperature and relative humidity (RH) controls (Wang et al., 2011). In each experiment, isoprene was allowed to oxidize during several hours in the presence on nitrogen oxides under dry conditions. Gas phase compounds were analyzed on-line by a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-ToF-MS), a Fourier Transform Infrared Spectrometer (FTIR), NOx and O3 analyzers. SOA formation was monitored on-line with a Scanning Mobility Particle Sizer (SMPS) and an Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). The experimental protocol was optimised to generate cloud events in the simulation chamber, which allowed us to generate clouds lasting for ca. 10 minutes in the presence of light.In all experiments, we observed that during cloud formation, water-soluble gas-phase oxidation products (e.g., methylglyoxal, hydroxyacetone, acetaldehyde, formic acid, acetic acid and glycolaldehyde) readily partitioned into cloud droplets and new SOA mass was promptly produced which partly persisted after cloud evaporation. Chemical composition, elemental ratios and density of SOA, measured with the HR-ToF-AMS, were compared before, during cloud formation and after cloud evaporation.

  15. 14 CFR 1261.104 - Allowable claims.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...be allowed for damage to, or loss of, property as a direct consequence...be allowed for damage to, or loss of, property when used for...be allowed for damage to, or loss of, clothing or accessories...person, such as eyeglasses, hearing aids or...

  16. 24 CFR 17.43 - Allowable claims.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...be allowed for damage to, or loss of, property as a direct consequence...be allowed for damage to, or loss of, property when used for...be allowed for damage to, or loss of, clothing or accessories...person, such as eyeglasses, hearing aids, or dentures....

  17. 29 CFR 15.22 - Allowable claims.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...be allowed for damage to, or loss of, property as a direct consequence...be allowed for damage to, or loss, of property when used for...be allowed for damage to, or loss of, clothing and accessories...person, such as eyeglasses, hearing aids, or dentures....

  18. Directivity of HXR Solar Flare Emission Obtained from Stereoscopic Observations by Mars Odyssey (HEND), RHESSI and CORONAS-F (SONG)

    Microsoft Academic Search

    Moisey Livshits; Dmitry Golovin; Igor Mitrofanov; S. Alexander Kozyrev; Maxim Litvak; Vladislav Tretyakov; Anton Sanin; William V. Boynton; Larisa Kashapova; Irina Myagkova; Andrey Bogomolov

    2010-01-01

    Two powerful X-Ray flares were observed on 2005, July 14 by three spacecrafts whose heliolon-gitudes were spaced on 39 degrees. The flares were observed, as projected on the solar disc by Mars Odyssey (HEND) and seeing almost directly on the limb by RHESSI and CORONAS-F. The most intensive hard X-ray and gamma-ray flare (up to 2 MeV) was observed by

  19. Direct observation of ferroelectric domain switching in varying electric field regimes using in situ TEM.

    PubMed

    Winkler, C R; Damodaran, A R; Karthik, J; Martin, L W; Taheri, M L

    2012-11-01

    In situ Transmission Electron Microscopy (TEM) techniques can potentially fill in gaps in the current understanding interfacial phenomena in complex oxides. Select multiferroic oxide materials, such as BiFeO(3) (BFO), exhibit ferroelectric and magnetic order, and the two order parameters are coupled through a quantum-mechanical exchange interaction. The magneto-electric coupling in BFO allows control of the ferroelectric and magnetic domain structures via applied electric fields. Because of these unique properties, BFO and other magneto-electric multiferroics constitute a promising class of materials for incorporation into devices such as high-density ferroelectric and magnetoresistive memories, spin valves, and magnetic field sensors. The magneto-electric coupling in BFO is mediated by volatile ferroelastically switched domains that make it difficult to incorporate this material into devices. To facilitate device integration, an understanding of the microstructural factors that affect ferroelastic relaxation and ferroelectric domain switching must be developed. In this article, a method of viewing ferroelectric (and ferroelastic) domain dynamics using in situ biasing in TEM is presented. The evolution of ferroelastically switched ferroelectric domains in BFO thin films during many switching cycles is investigated. Evidence of partial domain nucleation, propagation, and switching even at applied electric fields below the estimated coercive field is revealed. Our observations indicate that the occurrence of ferroelastic relaxation in switched domains and the stability of these domains is influenced the applied field as well as the BFO microstructure. These biasing experiments provide a real time view of the complex dynamics of domain switching and complement scanning probe techniques. Quantitative information about domain switching under bias in ferroelectric and multiferroic materials can be extracted from in situ TEM to provide a predictive tool for future device development. PMID:22459251

  20. Direct Microlensing-Reverberation Observations of the Intrinsic magnetic Structure of AGN in Different Spectral States: A Tale of Two Quasars

    E-print Network

    Rudolph E. Schild; Darryl J. Leiter; Stanley L. Robertson

    2007-08-17

    We show how direct microlensing-reverberation analysis performed on two well-known Quasars (Q2237 - The Einstein Cross and Q0957 - The Twin) can be used to observe the inner structure of two quasars which are in significantly different spectral states. These observations allow us to measure the detailed internal structure of quasar Q2237 in a radio quiet high-soft state, and compare it to quasar Q0957 in a radio loud low-hard state. We find that the observed differences in the spectral states of these two quasars can be understood as being due to the location of the inner radii of their accretion disks relative to the co-rotation radii of rotating intrinsically magnetic supermassive compact objects in the centers of these quasars.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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

  3. Direct Observation of Substitutional Au Atoms in SrTiO3

    SciTech Connect

    Wang, Chong M.; Shutthanandan, V.; Zhang, Yanwen; Thevuthasan, Suntharampillai; Duscher, Gerd

    2004-11-05

    Ion implantation and subsequent high-temperature annealing is an effective way to prepare metal nanoclusters dispersed in a dielectric for useful optical and electrical properties. However, there is very little understanding of the nucleation and growth process of these nanoclusters, their correlations with the sites of the implanted ions, and the behavior of defects (such as vacancies) generated during the ion-implantation process. Using high-angle annular dark-field imaging in aberration-corrected scanning transmission electron microscopy, we have directly observed that, at a dilute concentration, Au atoms implanted in SrTiO3 are in a substitutional lattice position for both Sr and Ti. Congregation of Au atoms by diffusion to a critical concentration leads to the nucleation of a Au lattice within the SrTiO3. The Au nanocluster and SrTiO3 were found to maintain an orientation relationship of Au[001]//SrTiO3[001] and Au(100)//SrTiO3(100), which corroborated the results of a first-principles total-energy calculation. The interface between the Au cluster and SrTiO3 was bridged by an O/Ti plane. The Au-O bond length was found to be 2.2 Å, which is the same as Au-O bond length in AuO. Furthermore, the atomic planes adjacent to the interface in both Au and SrTiO3 were found to be slightly stretched. The high concentration of vacancies generated during the Au implantation aggregated to form cavities in the SrTiO3 lattice, and were faceted mostly along the SrTiO3 {100} and (110) planes. The Au and vacancy clusters were spatially associated, indicating a strong interaction. Thus, the formation of cavities in Au-implanted materials indicates that the vacancy-clustering process prevails over the Frenkel-pair recombination.

  4. Isolating observer-based reference directions in human spatial memory: head, body, and the self-to-array axis.

    PubMed

    Waller, David; Lippa, Yvonne; Richardson, Adam

    2008-01-01

    Several lines of research have suggested the importance of egocentric reference systems for determining how the spatial properties of one's environment are mentally organized. Yet relatively little is known about the bases for egocentric reference systems in human spatial memory. In three experiments, we examine the relative importance of observer-based reference directions in human memory by controlling the orientation of head and body during acquisition. Experiment 1 suggests that spatial memory is organized by a head-aligned reference direction; however, Experiment 2 shows that a body-aligned reference direction can be more influential than a head-aligned direction when the axis defined by the relative positions of the observer and the learned environment (the "self-to-array" axis) is properly controlled. A third experiment shows that the self-to-array axis is distinct from - and can dominate - retina, head, and body-based egocentric reference systems. PMID:17316594

  5. Direct oxygen imaging within a ceramic interface, with some observations upon the dark contrast at the grain boundary.

    PubMed

    Findlay, S D; Azuma, S; Shibata, N; Okunishi, E; Ikuhara, Y

    2011-03-01

    Annular bright field scanning transmission electron microscopy, which has recently been established to produce directly interpretable images with both light and heavier atomic columns visible simultaneously, is shown to allow directly interpretable imaging of the oxygen columns within the ?13[12¯10](101¯4) pyramidal twin grain boundary in ?-Al(2)O(3). By using information in the high-angle annular dark field image and annular bright field images simultaneously, we estimate the specimen thickness and finite source size, and use them to explore in simulation the issue of dark contrast in the vicinity of the grain boundary in the annular dark field image. PMID:21353155

  6. Direct Spectroscopic Observation of the Structural Origin of Peroxide Generation from Co-Based Pyrolyzed Porphyrins for ORR Applications

    SciTech Connect

    Ziegelbauer,J.; Olson, T.; Pylypenko, S.; Alamgir, F.; Jaye, C.; Atanassov, P.; Mukerjee, S.

    2008-01-01

    Pyrolyzed transition metal based porphyrins present an attractive alternative to state of the art Pt-based electrocatalysts for fuel cell applications based on their comparatively low cost. Unfortunately, the large array of precursors and synthetic strategies has led to considerable ambiguity regarding the specific structure/property relationships that give rise to their activity for oxygen reduction. Specifically, considerable debate exists in actual chemical structure of the pyrolyzed reaction centers, and their relationship to membrane-damaging peroxide yield. In this manuscript a comprehensive electrochemical and spectroscopic study of pyrolyzed CoTMPP produced via a self-templating process is presented. The resulting electrocatalysts are not carbon-supported, but are highly porous self-supported pyropolymers. Rotating ring disk electrode measurements showed that the materials pyrolyzed at 700 C exhibited the highest performance, whereas pyrolysis at 800 C resulted in a significant increase in the peroxide yield. X-ray photoelectron spectroscopy and Co L and K edge extended X-ray absorption fine structure (EXAFS) studies confirm that the majority of the Co-N4 active site has broken down to Co-N2 at 800 C. Application of ?{mu} analysis (an X-ray absorption near-edge structure difference technique) to the in situ Co K edge EXAFS data allowed for direct spectroscopic observation of the geometry of Oads on the pyropolymer active sites. The specific geometrical adsorption of molecular oxygen with respect to the plane of the Co-Nx moieties highly influences the oxygen reduction reaction pathway. The application of the ?{mu} technique to other transition metal based macrocycle electrocatalyst systems is expected to provide similarly detailed information.

  7. Nano-aquarium for dynamic observation of aquatic microorganisms fabricated by femtosecond laser direct writing of photostructurable glass

    NASA Astrophysics Data System (ADS)

    Hanada, Y.; Sugioka, K.; Kawano, H.; Ishikawa, I.; Miyawaki, A.; Midorikawa, K.

    2008-02-01

    We demonstrate the fabrication of three-dimensional (3-D) hollow microstructures embedded in photostructurable glass by a femtosecond (fs) laser direct writing. Fs laser direct writing followed by annealing and successive wet etching in dilute hydrofluoric (HF) acid solution resulted in the rapid manufacturing of microchips with 3-D hollow microstructures for the dynamic observation of living microorganisms in fresh water. The embedded microchannel structure enables us to analyze the continuous motion of Euglena gracilis. A microchamber with a movable microneedle demonstrates its ability for the elucidation of the information transmission process in Pleurosira laevis. Such microchips, referred to as nano-aquariums realize the efficient and highly functional observation of microorganisms.

  8. Costs and cost-effectiveness of different DOT strategies for the treatment of tuberculosis in Pakistan. Directly Observed Treatment.

    PubMed

    Khan, M A; Walley, J D; Witter, S N; Imran, A; Safdar, N

    2002-06-01

    An economic study was conducted alongside a clinical trial at three sites in Pakistan to establish the costs and effectiveness of different strategies for implementing directly observed treatment (DOT) for tuberculosis. Patients were randomly allocated to one of three arms: DOTS with direct observation by health workers (at health centres or by community health workers); DOTS with direct observation by family members; and DOTS without direct observation. The clinical trial found no statistically significant difference in cure rate for the different arms. The economic study collected data on the full range of health service costs and patient costs of the different treatment arms. Data were also disaggregated by gender, rural and urban patients, by treatment site and by economic categories, to investigate the costs of the different strategies, their cost-effectiveness and the impact that they might have on patient compliance with treatment. The study found that direct observation by health centre-based health workers was the least cost-effective of the strategies tested (US dollars 310 per case cured). This is an interesting result, as this is the model recommended by the World Health Organization and International Union against Tuberculosis and Lung Disease. Attending health centres daily during the first 2 months generated high patient costs (direct and in terms of time lost), yet cure rates for this group fell below those of the non-observed group (58%, compared with 62%). One factor suggested by this study is that the high costs of attending may be deterring patients, and in particular, economically active patients who have most to lose from the time taken by direct observation. Without stronger evidence of benefits, it is hard to justify the costs to health services and patients that this type of direct observation imposes. The self-administered group came out as most cost-effective (164 dollars per case cured). The community health worker sub-group achieved the highest cure rates (67%), with a cost per case only slightly higher than the self-administered group (172 dollars per case cured). This approach should be investigated further, along with other approaches to improving patient compliance. PMID:12000778

  9. 49 CFR 40.67 - When and how is a directly observed collection conducted?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...each specimen a notation to this effect (e.g., collection 1 of...collector, you must ensure that the observer is the same gender as the employee...opposite gender person to act as the observer. The observer can be a different person...

  10. 49 CFR 40.67 - When and how is a directly observed collection conducted?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...each specimen a notation to this effect (e.g., collection 1 of...collector, you must ensure that the observer is the same gender as the employee...opposite gender person to act as the observer. The observer can be a different person...

  11. Direct observation of the microstructure and defects in KBe2BO3F2 crystals by TEM.

    PubMed

    Xu, Tao; Liu, Lijuan; Wang, Xiaoyang; Chen, Chuangtian; Zhou, Haitao; He, Xiaoling; Zhang, Changlong; Sun, Junliang

    2014-11-21

    We apply for the first time transmission electron microscopy to the direct observation of the deep-UV nonlinear optical crystal KBe2BO3F2 (KBBF) grown using different methods. Two kinds of electron diffraction patterns were observed in the hydrothermally synthesized KBBF along the [120] direction, which resulted from the coexistence of two structures with space groups R32 and R3[combining macron]c. As a comparison, the flux grown KBBF crystals show uniform R32 structures. Furthermore we observed a twin boundary in flux KBBF which corresponds to the (21[combining macron]3)R32 crystallographic plane. Two structure models are proposed here for the twin boundary. These observations on the microstructure and defects were not disclosed in previous powder XRD and optical microscopy experiments and shed new light on the understanding of the structure and defects of KBBF crystals. PMID:25247734

  12. Effect of wave directional spread on the radiation stress: comparing theory and observations

    Microsoft Academic Search

    Falk Feddersen

    2004-01-01

    Nearshore circulation and shoreline setup are forced through the wave radiation stress, which is a function of the frequency-directional wave spectrum. The radiation stress components often are approximated by assuming a spectrum that is narrow-band in frequency and direction. These narrow-band approximations overestimate the true radiation stress components in 8-m water depth on the Outer Banks, NC where locally generated

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

    Microsoft Academic Search

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

    2010-01-01

    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

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

    Microsoft Academic Search

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

    1963-01-01

    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

  15. Kinetic modeling of phase transformations occurring in the HAZ of C-Mn steel welds based on direct observations

    Microsoft Academic Search

    J. W. Elmer; T. A. Palmer; W. Zhang; B. Wood; T. DebRoy

    2003-01-01

    In situ Spatially Resolved X-Ray Diffraction (SRXRD) experiments were performed in the heat-affected zone (HAZ) of gas tungsten arc (GTA) welds of AISI 1005 C-Mn steel to directly observe welding induced phase transformations. These real-time observations were semi-quantified using diffraction peak profile analysis to construct a phase transformation map revealing ferrite (?) and austenite (?) phase concentration gradients in the

  16. Combined Flux Observer With Signal Injection Enhancement for Wide Speed Range Sensorless Direct Torque Control of IPMSM Drives

    Microsoft Academic Search

    Gheorghe-Daniel Andreescu; Cristian Ilie Pitic; Frede Blaabjerg; Ion Boldea

    2008-01-01

    This paper proposes a motion-sensorless control system using direct torque control with space vector modulation for interior permanent magnet synchronous motor (IPMSM) drives, for wide speed range operation, including standstill. A novel stator flux observer with variable structure uses a combined voltage-current model with PI compensator for low-speed operations. As speed increases, the observer switches gradually to a PI compensated

  17. Propagation directions of gravity wave patterns observed in OH CCD images during the SEEK campaign

    Microsoft Academic Search

    Takuji Nakamura; Toshitaka Tsuda; Hirohisa Miyagawa; Yoshihito Matsushita; Hiroshi Fukunishi; Yukihiro Takahashi; Yoshinori Yamada

    1998-01-01

    OH airglow (about 87 km altitude) was observed with a CCD imager at Shigaraki (34.9°N, 136.1°E) in August 1996, during the SEEK campaign period. From nine night observations, the characteristics of the gravity wave modulation of the OH airglow layer were extracted and analyzed. The distributions of the horizontal wavelength, observed wave period and horizontal phase speed were 10-30 km,

  18. Solar Physics (2004) 224: 34 C Springer 2005 The topical issue of "Space Climate: Direct and Indirect Observations of

    E-print Network

    Usoskin, Ilya G.

    2004-01-01

    Solar Physics (2004) 224: 3­4 C Springer 2005 PREFACE The topical issue of "Space Climate: Direct and Indirect Observations of Long-Term Solar Activity" is based on contributions presented at the First of solar activity, and their effects in the near-Earth environment and technoculture. As an analogy

  19. Direct Observation of Nanoscale Peltier and Joule Effects at Metal-Insulator Domain Walls in Vanadium Dioxide Nanobeams

    E-print Network

    Wu, Junqiao

    localized alternating Peltier heating and cooling as well as Joule heating concentrated at the M-I domainDirect Observation of Nanoscale Peltier and Joule Effects at Metal- Insulator Domain Walls the monoclinic phase identification. KEYWORDS: Vanadium dioxide, thermoreflectance microscopy, Peltier effect

  20. Commentary: What You See Is What You Get--A Commentary on School-Based Direct Observation Systems

    ERIC Educational Resources Information Center

    Landau, Steven; Swerdlik, Mark E.

    2005-01-01

    Direct observation is the hallmark example of broader behavior assessment. As such, it involves a systematic process in which behaviors, settings, and their reciprocal relationship are studied. As a process, behavior assessment relies on multiple methods and repeated measurement. Each component in the behavior assessment battery makes a unique…

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

    ERIC Educational Resources Information Center

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

    2006-01-01

    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…

  2. DIRECT MICROSCOPIC OBSERVATION AND VISUALIZATION OF CAMPYLOBACTER JEJUNI VIABILITY ON CHICKEN SKIN

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to develop a method to identify specific sites on chicken skin, which allow Campylobacter jejuni survival. This method employs confocal laser scanning microscopy (CSLM) visualization of Campylobacter jejuni transformed with Pcgfp plasmid (GFP-Campylobacter) exposed t...

  3. Direct electrical observation of plasma wave-related effects in GaN-based two-dimensional electron gases

    SciTech Connect

    Zhao, Y.; Chen, W.; Li, W.; Zhu, M.; Yue, Y.; Song, B.; Encomendero, J.; Xing, H.; Fay, P., E-mail: pfay@nd.edu [Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Sensale-Rodriguez, B. [Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)

    2014-10-27

    In this work, signatures of plasma waves in GaN-based high electron mobility transistors were observed by direct electrical measurement at room temperature. Periodic grating-gate device structures were fabricated and characterized by on-wafer G-band (140–220?GHz) s-parameter measurements as a function of gate bias voltage and device geometry. A physics-based equivalent circuit model was used to assist in interpreting the measured s-parameters. The kinetic inductance extracted from the measurement data matches well with theoretical predictions, consistent with direct observation of plasma wave-related effects in GaN-channel devices at room temperature. This observation of electrically significant room-temperature plasma-wave effects in GaN-channel devices may have implications for future millimeter-wave and THz device concepts and designs.

  4. The underlying magnetic field direction in Ulysses observations of the southern polar heliosphere

    SciTech Connect

    Forsyth, R.J.; Balogh, A. [The Blackett Laboratory, Imperial College, London (United Kingdom); Smith, E.J.; Murphy, N. [Jet Propulsion Laboratory, Pasadena, California (United States); McComas, D.J. [Los Alamos National Laboratory, Los Alamos, New Mexico (United States)

    1996-07-01

    Magnetic field data provided by the Ulysses spacecraft between May 1993 and January 1995 are presented for the south latitudes 30-80 dg. The deflections of the magnetic field direction are attributed to the intense Alfven waves. {copyright} {bold 1997 American Institute of Physics.}

  5. Direct Observation of Localized Parallel Electric Fields in a Space Plasma

    SciTech Connect

    Ergun, R. E.; Su, Y.-J.; Andersson, L.; Carlson, C. W.; McFadden, J. P.; Mozer, F. S.; Newman, D. L.; Goldman, M. V.; Strangeway, R. J.

    2001-07-23

    We report direct measurements of parallel electric fields related to particle acceleration in a collisionless space plasma. The electric field is that of a monotonic potential ramp localized to {approx}10 debye lengths along the magnetic field. Electrons accelerated by the parallel electric field are accompanied by intense electrostatic waves and nonlinear structures interpreted as electron phase-space holes.

  6. Direct observation of individual endogenous protein complexes in situ by proximity ligation

    Microsoft Academic Search

    Ola Söderberg; Mats Gullberg; Malin Jarvius; Karin Ridderstråle; Karl-Johan Leuchowius; Jonas Jarvius; Kenneth Wester; Per Hydbring; Fuad Bahram; Lars-Gunnar Larsson; Ulf Landegren

    2006-01-01

    Cellular processes can only be understood as the dynamic interplay of molecules. There is a need for techniques to monitor interactions of endogenous proteins directly in individual cells and tissues to reveal the cellular and molecular architecture and its responses to perturbations. Here we report our adaptation of the recently developed proximity ligation method to examine the subcellular localization of

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

    Microsoft Academic Search

    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

    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.

  8. Influence of Parenting Factors on Childhood Social Anxiety: Direct Observation of Parental Warmth and Control

    ERIC Educational Resources Information Center

    Rork, Kristine E.; Morris, Tracy L.

    2009-01-01

    The purpose of the present study is to determine the association of parenting behaviors and social anxiety in children. Three parental factors--including parental socialization, control, and warmth--were investigated in a sample of 31 two-parent families. Rather than solely relying upon retrospective questionnaires, this study incorporated direct…

  9. Allowable/Non-Allowable Expenses by Fund Type Expenditures

    E-print Network

    Zhuang, Yu

    , including bottled water Gifts, gift cards and gift certificates Goods and services for personal use LeaseAllowable/Non-Allowable Expenses by Fund Type Source Allowable Expenditures Commodities for state-appropriated funds Rev. 10/30/14 Page 1 #12;Allowable/Non-Allowable Expenses by Fund Type Source

  10. Direct observation of dangling bond motion in disordered silicon N. H. Nickel

    E-print Network

    Schiff, Eric A.

    -center resonance in polycrystalline silicon. Distinct temperature dependences were found in as- prepared and hydrogen-passivated polycrystalline silicon. This observation invalidates the identification largely control the electronic properties of disor- dered silicons--amorphous, polycrystalline

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

    Microsoft Academic Search

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

    1977-01-01

    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.

  12. Generation of digital terrain model and image interpretation by using EROS-Al stereo pair images observed from multiple directions

    NASA Astrophysics Data System (ADS)

    Suga, Y.; Ogawa, H.; Sugimura, T.

    2003-12-01

    This study focuses on the improvement of automatic DTM (Digital Terrain Model) generation by using the stereo pair images of high-resolution satellite data. There has been a problem how to precisely correct the registration of corresponding points that are used to estimate the elevation in stereo pair images. DTM is usually generated by a set of stereo pair images. In this study, the authors propose an automatic DTM generation using high-resolution satellite EROS-Al images observed from multiple directions. The image registration is preliminary examined in WGS-84 coordinates system derived from GPS observation to set up ground control points for the rectification of each stereo pair image, in addition, the precise registration is completely performed using the camera model of EROS-Al image. As for the matching of stereo pair images, an automatic image correlation processing is performed by means of searching in each pixel based on correlation coefficient of test window. In addition, the comparison with correlation was performed on every combination of stereo pair images observed from multiple directions of different azimuth and pointing angle for evaluating and improving of accuracy of DTM. DTM is successfully generated by means of the above procedure proposed in this study. As the result, the residual error of registration was estimated 1.15 pixel in the mean rms at pixel direction and 1.47 pixel in the mean rms at line direction on each stereo pair image, and the residual error of DTM was distributed from + 11 m to -14 m approximately corresponding to GPS data on the ground. Finally, the authors verified that the stereo pair images observed from multiple directions have not only a capability to precisely generate DTM, but also a capability of improvement of image interpretation for identifying the structure of land covers, facilities and the geographical features by generating the color composite images consisted of each stereo pair image. 2003 COSPAR.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

  14. Direct Observation of Reversible Magnesium Ion Intercalation into a Spinel Oxide Host.

    PubMed

    Kim, Chunjoong; Phillips, Patrick J; Key, Baris; Yi, Tanghong; Nordlund, Dennis; Yu, Young-Sang; Bayliss, Ryan D; Han, Sang-Don; He, Meinan; Zhang, Zhengcheng; Burrell, Anthony K; Klie, Robert F; Cabana, Jordi

    2015-06-01

    Direct evidence of Mg(2+) intercalation into a spinel-type Mn2 O4 is provided. By com-bining tools with different sensitivities, from atomic-resolution X-ray spectro-scopy to bulk X-ray diffraction, it is demonstrated that Mg(2+) reversibly occupies the tetrahedral sites of the spinel structure through the reduction of Mn when the electrochemical reaction is performed. PMID:25882455

  15. Direct Observation of the Resistive Wall Mode in a Tokamak and Its Interaction with Plasma Rotation

    SciTech Connect

    Garofalo, A.M.; Bialek, J.; Navratil, G.A.; Sabbagh, S.A. [Columbia University, New York, New York 10027 (United States)] [Columbia University, New York, New York 10027 (United States); Turnbull, A.D.; Chu, M.S.; Groebner, R.J.; La Haye, R.J.; Lao, L.L.; Osborne, T.H.; Scoville, J.T.; Strait, E.J.; Taylor, T.S. [General Atomics, San Diego, California 92186-5608 (United States)] [General Atomics, San Diego, California 92186-5608 (United States); Austin, M.E. [The University of Texas at Austin, Austin, Texas 78712 (United States)] [The University of Texas at Austin, Austin, Texas 78712 (United States); Comer, K.J. [University of Wisconsin, Madison, Wisconsin 53706-1687 (United States)] [University of Wisconsin, Madison, Wisconsin 53706-1687 (United States); Fredrickson, E.D. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Lazarus, E.A. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)] [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Rice, B.W. [Lawrence Livermore National Laboratory, Livermore, California 94551-9900 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94551-9900 (United States)

    1999-05-01

    Using newly developed techniques and improved diagnostics, rotating wall-stabilized discharges have been maintained in the DIII-D tokamak for 30 characteristic resistive wall decay times{emdash}significantly longer than was previously achieved. The terminating resistive wall mode has been directly identified using internal fluctuation diagnostics, and its correlation with the slowdown in the plasma rotation is established. {copyright} {ital 1999} {ital The American Physical Society}

  16. Direct Observation of Beam Bunching Produced by a High Power Microwave Free-Electron Laser

    Microsoft Academic Search

    J. Gardelle; J. Labrouche; J. L. Rullier

    1996-01-01

    In this Letter we present a direct measurement of beam bunching by a high power free-electron laser (FEL). An induction linac delivered a 1 kA, 2.2 MeV electron beam to a FEL in which a 35 GHz input signal was amplified to power levels of the order of 10 MW. Measurements using both electronic and optical techniques were performed at

  17. High-temperature corrosion observed in austenitic coils and tubes in a direct reduction process

    Microsoft Academic Search

    B. Campillo; C. Gonzales; G. Hernandez-Duque; J. A. Juarez-Islas

    2000-01-01

    The subject of this study is related to the performance of austenitic steel coils and tubes, in a range of temperatures between\\u000a 425 and 870C for the transport of reducing gas, in an installation involving the direct reduction of iron-ore by reforming\\u000a natural gas. Evidence is presented that metal dusting is not the only unique high-temperature corrosion mechanism that caused

  18. Direct observation of magnetic gradient in Co\\/Pd pressure-graded media

    Microsoft Academic Search

    B. J. Kirby; S. M. Watson; J. E. Davies; G. T. Zimanyi; Kai Liu; R. D. Shull; J. A. Borchers

    2009-01-01

    Magnetometry and neutron scattering have been used to study the magnetic properties of pressure-graded Co\\/Pd multilayers. The grading of the multilayer structure was done by varying the deposition pressure during sputtering of the samples. Magnetic depth profiling by polarized neutron reflectometry directly shows that for pressure-graded samples, the magnetization changes significantly from one pressure region to the next, while control

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

    Microsoft Academic Search

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

    2010-01-01

    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

  20. Observation of Direct CP Violation in KS,L --> pipi Decays

    Microsoft Academic Search

    A. Alavi-Harati; I. F. Albuquerque; T. Alexopoulos; M. Arenton; K. Arisaka; S. Averitte; A. R. Barker; L. Bellantoni; A. Bellavance; J. Belz; R. Ben-David; D. R. Bergman; E. Blucher; G. J. Bock; C. Bown; S. Bright; E. Cheu; S. Childress; R. Coleman; M. D. Corcoran; G. Corti; B. Cox; M. B. Crisler; A. R. Erwin; R. Ford; A. Glazov; A. Golossanov; G. Graham; J. Graham; K. Hagan; E. Halkiadakis; K. Hanagaki; S. Hidaka; Y. B. Hsiung; V. Jejer; J. Jennings; D. A. Jensen; R. Kessler; H. G. Kobrak; J. Ladue; A. Lath; A. Ledovskoy; P. L. McBride; A. P. McManus; P. Mikelsons; E. Monnier; T. Nakaya; U. Nauenberg; K. S. Nelson; H. Nguyen; V. O'dell; M. Pang; R. Pordes; V. Prasad; C. Qiao; B. Quinn; E. J. Ramberg; R. E. Ray; A. Roodman; M. Sadamoto; S. Schnetzer; K. Senyo; P. Shanahan; P. S. Shawhan; W. Slater; N. Solomey; S. V. Somalwar; R. L. Stone; I. Suzuki; E. C. Swallow; R. A. Swanson; S. A. Taegar; R. J. Tesarek; G. B. Thomson; P. A. Toale; A. Tripathi; R. Tschirhart; Y. W. Wah; J. Wang; H. B. White; J. Whitmore; B. Winstein; R. Winston; J.-Y. Wu; T. Yamanaka; E. D. Zimmerman

    1999-01-01

    We have compared the decay rates of KL and KS to pi+pi- and pi0pi0 final states using a subset of the data from the KTeV experiment (E832) at Fermilab. We find that the direct-CP-violation parameter Re\\\\(?'\\/?\\\\) is equal to [28.0+\\/-3.0\\\\(stat\\\\)+\\/-2.8\\\\(syst\\\\)]×10-4. This result definitively establishes the existence of CP violation in a decay process.

  1. Direct mapping rather than motor prediction subserves modulation of corticospinal excitability during observation of actions in real time.

    PubMed

    Gueugneau, Nicolas; Mc Cabe, Sofia I; Villalta, Jorge I; Grafton, Scott T; Della-Maggiore, Valeria

    2015-06-01

    Motor facilitation refers to the specific increment in corticospinal excitability (CSE) elicited by the observation of actions performed by others. To date, the precise nature of the mechanism at the basis of this phenomenon is unknown. One possibility is that motor facilitation is driven by a predictive process reminiscent of the role of forward models in motor control. Alternatively, motor facilitation may result from a model-free mechanism by which the basic elements of the observed action are directly mapped onto their cortical representations. Our study was designed to discern these alternatives. To this aim, we recorded the time course of CSE for the first dorsal interosseous (FDI) and the abductor digiti minimi (ADM) during observation of three grasping actions in real time, two of which strongly diverged in kinematics from their natural (invariant) form. Although artificially slow movements used in most action observation studies might enhance the observer's discrimination performance, the use of videos in real time is crucial to maintain the time course of CSE within the physiological range of daily actions. CSE was measured at 4 time points within a 240-ms window that best captured the kinematic divergence from the invariant form. Our results show that CSE of the FDI, not the ADM, closely follows the functional role of the muscle despite the mismatch between the natural and the divergent kinematics. We propose that motor facilitation during observation of actions performed in real time reflects the model-free coding of perceived movement following a direct mapping mechanism. PMID:25810483

  2. Direct observations of plasma upflows and condensation in a catastrophically cooling solar transition region loop

    SciTech Connect

    Orange, N. B.; Chesny, D. L.; Oluseyi, H. M.; Hesterly, K.; Patel, M.; Champey, P. [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States)

    2013-12-01

    Minimal observational evidence exists for fast transition region (TR) upflows in the presence of cool loops. Observations of such occurrences challenge notions of standard solar atmospheric heating models as well as their description of bright TR emission. Using the EUV Imaging Spectrometer on board Hinode, we observe fast upflows (v {sub ?} ? –10 km s{sup –1}) over multiple TR temperatures (5.8 ?log T ? 6.0) at the footpoint sites of a cool loop (log T ? 6.0). Prior to cool loop energizing, asymmetric flows of +5 km s{sup –1} and –60 km s{sup –1} are observed at footpoint sites. These flows, speeds, and patterns occur simultaneously with both magnetic flux cancellation (at the site of upflows only) derived from the Solar Dynamics Observatory's Helioseismic Magnetic Imager's line-of-sight magnetogram images, and a 30% mass influx at coronal heights. The incurred non-equilibrium structure of the cool loop leads to a catastrophic cooling event, with subsequent plasma evaporation indicating that the TR is the heating site. From the magnetic flux evolution, we conclude that magnetic reconnection between the footpoint and background field is responsible for the observed fast TR plasma upflows.

  3. Direct observations of sigma phase growth and dissolution in 2205 duplex stainless steel

    SciTech Connect

    Palmer, T.A.; Elmer, J.W.; Babu, S.S.; Specht, E.D. (LLNL); (ORNL)

    2007-10-10

    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.

  4. Direct Observation of Broadband Coating Thermal Noise in a Suspended Interferometer

    E-print Network

    Black, E D; Barbary, K; Bushmaker, A; Heefner, J; Kawamura, S; Kawazoe, F; Matone, L; Meidt, S; Rao, S R; Schulz, K; Zhang, M; Libbrecht, K G; Black, Eric D.; Villar, Akira; Barbary, Kyle; Bushmaker, Adam; Heefner, Jay; Kawamura, Seiji; Kawazoe, Fumiko; Matone, Luca; Meidt, Sharon; Rao, Shanti R.; Schulz, Kevin; Zhang, Michael; Libbrecht, Kenneth G.

    2004-01-01

    We report observations of broadband displacement noise resulting from thermal fluctuations in the mirror coatings of a high-sensitivity suspended interferometer. These observations show the expected spectral signature for coating thermal noise over almost two decades in frequency, but the noise amplitude (5e-19 to 1.5e-18 m/rHz) is lower than has been previously predicted. Ringdown measurements of the mechanical Q's of coated optics similar to our test masses lead to predictions of a minimum thermal noise that is greater than what we observe in our interferometer. Broadband coating thermal noise in similar low-loss coatings is a fundamental noise source that is expected to ultimately limit the astrophysical reach of interferometric gravitational wave detectors.

  5. Instructions for observing air temperature, humidity, and direction and force of wind

    USGS Publications Warehouse

    U.S. Geological Survey

    1892-01-01

    Description of instruments.-The temperature and humidity of the air are obtained from the simultaneous observation of a pair of mercurial thermometers termed the dry and the wet bulb. The air temperature is given by the dry-bulb thermometer, and the humidity is obtained from the combined readings of both. The wet-bulb thermometer differs from the dry-bulb thermometer only in having its bulb covered with thin muslin, which is wetted in pure water at each observation.The two thermometers are fastened in a light metal 'or wooden frame. To this frame is to be attached a stout cord for the whirling of the thermometers, which is an essential part of every observation.

  6. Direct and remotely-sensed observations of water vapor isotopes in the North American Monsoon domain

    NASA Astrophysics Data System (ADS)

    Berkelhammer, M. B.; Langford, S.; Buenning, N. H.; Yoshimura, K.; Frankenberg, C.; Kaushik, A.; Noone, D. C.

    2012-12-01

    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.

  7. An Improved Microscope Stage for Direct Observation of Freezing and Freeze Drying

    Microsoft Academic Search

    Steven L. Nail; Lih-Min Her; Christopher P. B. Proffitt; Lisa L. Nail

    1994-01-01

    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,

  8. Catecholamine-Induced Leukocytosis: Early Observations, Current Research, and Future Directions

    Microsoft Academic Search

    Robert J. Benschop; Mario Rodriguez-Feuerhahn; Manfred Schedlowski

    1996-01-01

    Recent studies demonstrate that acute psychological stress in man affects lymphocyte circulation. It has been suggested that catecholamines are responsible for these changes. The present review summarizes findings regarding catecholamine-induced lympho- and leukocytosis, starting with observations dating back to the beginning of this century. Particular attention is given to the mechanisms of this phenomenon and the potential site of origin

  9. Direct Observation of the Intersection of Sequence Faults in the Fe-Cr sigma-Phase

    Microsoft Academic Search

    Tsutomu Ishimasa; Yasuyuki Kitano; Yukitomo Komura

    1980-01-01

    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

  10. OBSERVATIONS OF BI-DIRECTIONAL FIELD ALIGNED ELECTRONS AND SOLITARY WAVES IN

    E-print Network

    Fillingim, Matthew

    , observations of low frequency broadband electrostatic noise (BEN) in the plasma sheet [Scarf et al., 1974, 2685, 1996. Parks, G. K., et al., J. Geophys. Res., 84, 2651, 1979. Scarf, F. L., et al., Geophys. Res of the waves? Produced locally by interacting streams of electrons? Propagate from the ionosphere? How do

  11. Value-Directed Human Behavior Analysis from Video Using Partially Observable Markov Decision Processes

    Microsoft Academic Search

    Jesse Hoey; James J. Little

    2007-01-01

    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

  12. Direct and Remote Sensing Observations of the Effects of Ships on Clouds

    Microsoft Academic Search

    LAWRENCE F. UDKE; JAMES A. COAKLEY; MICHAEL D. KING

    1989-01-01

    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

  13. Direct Observation of Magnetic Frustration via Bond-directional Interactions in a Honeycomb Lattice Iridate Na2IrO3

    NASA Astrophysics Data System (ADS)

    Chun, Sae Hwan; Zheng, H.; Stoumpos, C.; Malliakas, C.; Mitchell, J. F.; Kim, Jong-Woo; Kim, Jungho; Choi, Y.; Gog, T.; Mehlawat, Kavita; Singh, Yogesh; Al-Zein, A.; Sala, M. Morreti; Krisch, M.; Chaloupka, J.; Jackeli, G.; Khaliullin, G.; Kim, B. J.

    2015-03-01

    Despite its long-range zigzag magnetic ground state, the honeycomb Na2IrO3 is considered as a model system for approaching a Kitaev quantum spin liquid due to a proposed bond-directional magnetic frustration. Using resonant x-ray magnetic scattering, we find direct evidence of this frustration and follow its temperature dependence. We observe that three zigzag magnetic states with short-range correlation are displayed in the diffuse magnetic peaks as a function of scattering geometry up to 6TN. Each zigzag state breaks C3 symmetry individually, but the simultaneous C3 rotation in both real and spin spaces remains invariant as consequence of the distinct magnetic anisotropies tied to three Ir-Ir bonds in the lattice. This result confirms the dominant role of the bond-directional interactions in the frustration. Work in the Materials Science Division at Argonne National Laboratory supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Division of Materials Science and Engineering.

  14. Direct observation of magnetically induced phase separation in Co-W sputtered thin films

    NASA Astrophysics Data System (ADS)

    Oikawa, K.; Qin, G. W.; Sato, M.; Okamoto, S.; Kitakami, O.; Shimada, Y.; Fukamichi, K.; Ishida, K.; Koyama, T.

    2004-09-01

    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.

  15. Comment on "direct observation of laser filamentation in high-order harmonic generation".

    PubMed

    Tosa, Valer; Nam, Chang Hee

    2007-09-15

    We argue for a different physical interpretation of the results given in the recent Letter by Painter et al. [Opt. Lett.31, 3471 (2006)] in which an elongated Ti:saphire beam with two distinct waists is considered as direct evidence of laser filamentation. As the pulse power is well below the critical power for self-focusing, the authors pleaded for new examination of the n(2) value for He. A three-dimensional numerical modeling, using the published n(2) value for He, reproduces very well the measured data and invalidates the filamentation hypothesis. PMID:17873942

  16. Direct observation of bis-sulfur ligation to the heme of bacterioferritin

    SciTech Connect

    George, G.N. [Stanford Univ., CA (United States); Richards, T.; Watt, G.D. [Brigham Young Univ., Provo, UT (United States); Bare, R.E.; Gea, Y.; Prince, R.C.; Stiefel, E.I. [Exxon Research and Engineering Company, Annandale, NJ (United States)

    1993-08-25

    X-ray absorption spectroscopy was used to examine the ligation of the heme of Azobacter vinelandii bacterioferritin scrupulously cleaned of non-heme iron. We find that the iron of the protoporphyrin IX of the protein has two axial sulfur ligands at 2.35 A, with four nitrogen ligands at 1.97 A. This result confirms the previous suggestion of Cheesman et al., on the basis of less direct spectroscopic techniques, that the heme of bacterioferritin is ligated by a pair of methionine ligands. To date, this mode of coordination is unknown in any other heme protein. 22 refs., 3 figs., 1 tab.

  17. ARTEX - in-situ observation of directional solidification of Al-Si alloys on TEXUS 39

    NASA Astrophysics Data System (ADS)

    Ahrweiler, Sonja; Ratke, Lorenz; Masslow, Hans Dieter

    2003-08-01

    The goal of the experiment in the ARTEX furnace facility (Aerogel technology for microgravity solidification on TEXUS) during the sounding rocket flight TEXUS 39 in May 2001 was twofold, consisting primarily in the technology demonstration of the furnace equipped with the fragile aerogels as a was submitted to directional solidification in order to determine the influence of diffusive versus convective material transport conditions on the microstructure evolution. The scientific objective was defined by the ESA-MAP MICAST project studying the influence of controlled convection on the microstructure evolution.

  18. Direct Observation and Calipering of the {open_quotes}Webbing{close_quotes} Fermi Surface of Yttrium

    SciTech Connect

    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

    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}

  19. Direct observation of magnetically induced phase separation in Co-W sputtered thin films

    SciTech Connect

    Oikawa, K.; Qin, G.W.; Sato, M.; Okamoto, S.; Kitakami, O.; Shimada, Y.; Fukamichi, K.; Ishida, K.; Koyama, T. [National Institute of Advanced Industrial Science and Technology, Sendai 983-8551 (Japan); Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan); National Institute for Materials Science, Ibaraki 305-0047 (Japan)

    2004-09-27

    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.

  20. Simulation of Channel Segregation During Directional Solidification of In—75 wt pct Ga. Qualitative Comparison with In Situ Observations

    NASA Astrophysics Data System (ADS)

    Saad, Ali; Gandin, Charles-André; Bellet, Michel; Shevchenko, Natalia; Eckert, Sven

    2015-05-01

    Freckles are common defects in industrial casting. They result from thermosolutal convection due to buoyancy forces generated from density variations in the liquid. The present paper proposes a numerical analysis for the formation of channel segregation using the three-dimensional (3D) cellular automaton (CA)—finite element (FE) model. The model integrates kinetics laws for the nucleation and growth of a microstructure with the solution of the conservation equations for the casting, while introducing an intermediate modeling scale for a direct representation of the envelope of the dendritic grains. Directional solidification of a cuboid cell is studied. Its geometry, the alloy chosen as well as the process parameters are inspired from experimental observations recently reported in the literature. Snapshots of the convective pattern, the solute distribution, and the morphology of the growth front are qualitatively compared. Similitudes are found when considering the coupled 3D CAFE simulations. Limitations of the model to reach direct simulation of the experiments are discussed.

  1. Transmission Electron Microscope In Situ Straining Technique to Directly Observe Defects and Interfaces During Deformation in Magnesium

    NASA Astrophysics Data System (ADS)

    Morrow, B. M.; Cerreta, E. K.; McCabe, R. J.; Tomé, C. N.

    2015-05-01

    In situ straining was used to study deformation behavior of hexagonal close-packed (hcp) metals. Twinning and dislocation motion, both essential to plasticity in hcp materials, were observed. Typically, these processes are characterized postmortem by examining remnant microstructural features after straining has occurred. By imposing deformation during imaging, direct observation of active deformation mechanisms is possible. This work focuses on straining of structural metals in a transmission electron microscope (TEM), and a recently developed technique that utilizes familiar procedures and equipment to increase ease of experiments. In situ straining in a TEM presents several advantages over conventional postmortem characterization, most notably time resolution of deformation and streamlined identification of active deformation mechanisms. Drawbacks to the technique and applicability to other studies are also addressed. In situ straining is used to study twin boundary motion in hcp magnesium. A {10bar{1}2} } twin was observed during tensile and compressive loading. Twin-dislocation interactions are directly observed. Notably, dislocations are observed to remain mobile, even after multiple interactions with twin boundaries; this result suggests that Basinki's dislocation transformation mechanism by twinning is not present in hcp metals. The coupling of in situ straining with traditional postmortem characterization yields more detailed information about material behavior during deformation than either technique alone.

  2. Direct observation of N-(group V) bonding defects in dilute nitride semiconductors using hard x-ray photoelectron spectroscopy

    SciTech Connect

    Ishikawa, F.; Fuyuno, S.; Higashi, K.; Kondow, M. [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Machida, M.; Oji, H.; Son, J.-Y. [Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo, Hyogo 679-5143 (Japan); Trampert, A. [Paul-Drude-Institute fuer Festkoeperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany); Umeno, K.; Furukawa, Y.; Wakahara, A. [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan)

    2011-03-21

    Using bulk sensitive hard x-ray photoelectron spectroscopy, we directly observe a spectrum related to N-As bonding defects in (Ga,In)(N,As)/Ga(N,As) heterostructure. The defects are most likely attributed to split interstitials. Their concentration is in the order of 10{sup 19} cm{sup -3}, close to the detection limit of the measurement. Rapid thermal annealing eliminates the defects, leading to those undetectable. Similar phenomenon is observed for N-P bonding defects in In(N,P). The results indicate common features in dilute nitride semiconductor system: existence of N-(group V) bonding defects and their behavior on postgrowth annealing.

  3. Direct observation of dynamic charge stripes in La2 xSrxNiO4

    SciTech Connect

    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

    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.

  4. Direct observation of oil consumption mechanisms in a production spark ignition engine using fluorescence techniques

    NASA Astrophysics Data System (ADS)

    Lusted, Roderick M.

    1994-05-01

    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.

  5. Direct observation of dynamic charge stripes in La2-xSrxNiO4

    NASA Astrophysics Data System (ADS)

    Anissimova, S.; Parshall, D.; Gu, G. D.; Marty, K.; Lumsden, M. D.; Chi, Songxue; Fernandez-Baca, J. A.; Abernathy, D. L.; Lamago, D.; Tranquada, J. M.; Reznik, D.

    2014-03-01

    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.

  6. Analytic Bounds on Causal Risk Differences in Directed Acyclic Graphs Involving Three Observed Binary Variables.

    PubMed

    Kaufman, Sol; Kaufman, Jay S; Maclehose, Richard F

    2009-10-01

    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)

  7. Connecting the direct detection of dark matter with observation of sparticles at the LHC

    SciTech Connect

    Feldman, Daniel [Michigan Center for Theoretical Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States); Liu Zuowei [C. N. Yang Institute for Theoretical Physics, Stony Brook University, Stony Brook, New York 11794 (United States); Kavli Institute for Theoretical Physics China, Chinese Academy of Science, Beijing, 100190 (China); Nath, Pran [Department of Physics, Northeastern University, Boston, Massachusetts 02115 (United States)

    2010-05-01

    An analysis is given connecting event rates for the direct detection of neutralino dark matter with the possible signatures of supersymmetry at the LHC. It is shown that if an effect is seen in the direct detection experiments at a level of O(10{sup -44}) cm{sup 2} for the neutralino-proton cross section, then within the minimal supergravity grand unified model the next heavier particle above the neutralino is either a stau, a chargino, or a CP odd/CP even (A/H) Higgs boson. Further, the collider analysis shows that models with a neutralino-proton cross section at the level of (1-5)x10{sup -44} cm{sup 2} could be probed with as little as 1 fb{sup -1} of integrated luminosity at the LHC at {radical}(s)=7, 10 TeV. The most recent limit from the five tower CDMS II result on weakly interacting massive particle-nucleon cross section is discussed in this context. It is argued that the conclusions of the analysis given here are more broadly applicable with inclusion of nonuniversalities in the supergravity grand unified models.

  8. Observation of an ionospheric acceleration mechanism producing energetic (keV) ions primarily normal to the geomagnetic field direction

    Microsoft Academic Search

    R. D. Sharp; R. G. Johnson; E. G. Shelley

    1977-01-01

    O\\/sup +\\/ ions with energies of approximately 1 keV have been observed flowing upward out of the ionosphere with a pitch angle distribution having a minimum along the magnetic field direction and maxima in about 130°⁻⁻¹⁴°sup 0\\/ range. The measurements were obtained with an energetic ion mass spectrometer experiment on the satellite 1976-65B at an altitude of about 7600 km

  9. Direct observation of the topological charge of a terahertz vortex beam generated by a Tsurupica spiral phase plate

    SciTech Connect

    Miyamoto, K., E-mail: k-miyamoto@faculty.chiba-u.jp [Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Suizu, K.; Akiba, T. [Department of Electrical, Electronics and Computer Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016 (Japan); Omatsu, T. [Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); CREST Japan Science and Technology Agency, Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan)

    2014-06-30

    A terahertz (THz) spiral phase plate with high transmission (>90% after Fresnel correction) and low dispersion has been developed based on the Tsurupica olefin polymer. Direct observations of the topological charge (both magnitude and sign) of a THz vortex beam are performed by using a THz camera with tilted lens focusing and radial defect introduction. The vortex outputs with a topological charge of ±1 (or ±2) are obtained at a frequency of 2 (or 4) THz.

  10. Nano-aquarium for dynamic observation of living cells fabricated by femtosecond laser direct writing of photostructurable glass

    Microsoft Academic Search

    Yasutaka Hanada; Koji Sugioka; Hiroyuki Kawano; Ikuko Shihira Ishikawa; Atsushi Miyawaki; Katsumi Midorikawa

    2008-01-01

    We demonstrate the fabrication of three-dimensional (3-D) hollow microstructures embedded in photostructurable glass by a\\u000a nonlinear multiphoton absorption process using a femtosecond (fs) laser. Fs laser direct writing followed by annealing and\\u000a successive wet etching in dilute hydrofluoric (HF) acid solution resulted in the rapid manufacturing of microchips with 3-D\\u000a hollow microstructures for the dynamic observation of living microorganisms and

  11. Motion of single wandering diblock-macromolecules directed by a PTFE nano-fence: real time SFM observations.

    PubMed

    Gallyamov, Marat O; Qin, Shuhui; Matyjaszewski, Krzysztof; Khokhlov, Alexei; Möller, Martin

    2009-07-21

    Using SFM we have observed a peculiar twisting motion of diblock macromolecules pre-collapsed in ethanol vapour during their subsequent spreading in water vapour. The intrinsic asymmetry of the diblock macromolecules has been considered to be the reason for such twisting. Further, friction-deposited PTFE nano-stripes have been employed as nano-trails with the purpose of inducing lateral directed motion of the asymmetric diblock macromolecules under cyclic impact from the changing vapour surroundings. Indeed, some of the macromolecules have demonstrated a certain tendency to orient along the PTFE stripes, and some of the oriented ones have moved occasionally in a directed manner along the trail. However, it has been difficult to reliably record such directed motion at the single molecule level due to some mobility of the PTFE nano-trails themselves in the changing vapour environment. In vapours, the PTFE stripes have demonstrated a distinct tendency towards conjunction. This tendency has manifested itself in efficient expelling of groups of the mobile brush-like molecules from the areas between two PTFE stripes joining in a zip-fastener manner. This different kind of vapour-induced cooperative macromolecular motion has been reliably observed as being directed. The PTFE nano-frame experiences some deformation when constraining the spreading macromolecules. We have estimated the possible force causing such deformation of the PTFE fence. The force has been found to be a few pN as calculated by a partial contribution from every single molecule of the constrained group. PMID:19842476

  12. Direct in situ observations of single Fe atom catalytic processes and anomalous diffusion at graphene edges

    PubMed Central

    Zhao, Jiong; Deng, Qingming; Avdoshenko, Stanislav M.; Fu, Lei; Eckert, Jürgen; Rümmeli, Mark H.

    2014-01-01

    Single-atom catalysts are of great interest because of their high efficiency. In the case of chemically deposited sp2 carbon, the implementation of a single transition metal atom for growth can provide crucial insight into the formation mechanisms of graphene and carbon nanotubes. This knowledge is particularly important if we are to overcome fabrication difficulties in these materials and fully take advantage of their distinct band structures and physical properties. In this work, we present atomically resolved transmission EM in situ investigations of single Fe atoms at graphene edges. Our in situ observations show individual iron atoms diffusing along an edge either removing or adding carbon atoms (viz., catalytic action). The experimental observations of the catalytic behavior of a single Fe atom are in excellent agreement with supporting theoretical studies. In addition, the kinetics of Fe atoms at graphene edges are shown to exhibit anomalous diffusion, which again, is in agreement with our theoretical investigations. PMID:25331874

  13. Direct observations of the decay of beauty particles into charm particles

    NASA Astrophysics Data System (ADS)

    Albanese, J. P.; Alpe, V.; Aoki, S.; Arnold, R.; Baroni, G.; Barth, M.; Bartley, J. H.; Bertrand, D.; Bertrand-Coremans, G.; Bisi, V.; Breslin, A. C.; Carboni, G.; Chesi, E.; Chiba, K.; Cook, G. S.; Coupland, M.; Crosetti, G.; Davis, D. H.; Dell'Uomo, S.; Di Liberto, S.; Bonnelly, W.; Duff, B. G.; Esten, M. J.; Gamba, D.; Gerke, C.; Hazama, M.; Heymann, F. F.; Hoshino, K.; Imrie, D. C.; Isokane, Y.; Kazuno, M.; Kodama, Y.; Lush, G. J.; Maeda, Y.; Marzari-Chiesa, A.; Mazzoni, M. A.; Meddi, F.; Miyanishi, M.; Montwill, A.; Muciaccia, M. T.; Musset, P.; Nakamura, M.; Nakazawa, K.; Natali, S.; Niu, K.; Niwa, K.; Nuzzo, S.; Ohashi, M.; Piuz, F.; Poulard, G.; Ramello, L.; Riccati, L.; Romano, G.; Roosen, R.; Rosa, G.; Ruggieri, F.; Sato, Y.; Sasaki, H.; Sgarbi, C.; Shibuya, H.; Simone, S.; Sletten, H.; Tasaka, S.; Tesuka, I.; Tomita, Y.; Tovee, D. N.; Trent, P.; Tsuneoka, Y.; Ushida, N.; Yamakawa, O.; Yanagisawa, Y.

    1985-08-01

    The associated production of a pair of beauty particles B - and overlineB0 by a 350 GeV ? - interaction has been observed in an emulsion target inserted in an array of silicon microstrip detectors. Both beauty particles decay into charm particles, both of which are also observed to decay in the emulsion. Two negative muons were identified and their momenta measured in a large muon spectrometer. One muon has a pT of 1.9 GeV/ c and is associated with a beauty particle decay. The other, with a pT of 0.45 GeV/ c is associated with a charm particle decay. The flight times of the two beauty particles are respectively (0.8 ± 0.1) × 10 -13 s and (5 +2-1) × 10 -13 s. Alternative interpretations of this event have negligible probability.

  14. Direct measurements of stacking-fault energies from observations of dislocation nodes

    Microsoft Academic Search

    A. Howie; P. R. Swann

    1961-01-01

    From measurements of the radius of curvature of extended dislocation nodes observed by transmission electron microscopy, stacking-fault energies have been determined for a number of copper and silver base aluminium and zinc solid solution alloys and also for a number of nickel-cobalt alloys. Rough estimates of about 40, 25 and 150 erg cm respectively can be made of the stacking-fault

  15. Direct observation of strain-induced magnetic domain evolution in Heusler shape memory compounds

    Microsoft Academic Search

    C. A. Jenkins; A. Scholl; A. Doran; T. Omori

    2011-01-01

    The magnetic domain structure in single crystals of a novel Heusler magnetic shape memory (MSM) compound Fe2MnGa was observed to undergo strain-induced evolution by synchrotron-based photoelectron emission microscopy (PEEM) at Beamline 11.0.1 of the Advanced Light Source. PEEM can produce high resolution, surface-sensitive images reflecting the spatial distribution of magnetism, and a custom flexure rig has been designed for in

  16. First Direct Observation of Stable Internally Ordered Janus Nanoparticles Created by Lipid Self-Assembly.

    PubMed

    Tran, Nhiem; Mulet, Xavier; Hawley, Adrian M; Conn, Charlotte E; Zhai, Jiali; Waddington, Lynne J; Drummond, Calum J

    2015-06-10

    We present the first observation of Janus nanoparticles consisting of stable, coexisting ordered mesophases in discrete particles created by lipid self-assembly. Cryo-TEM images provided visual identification of the multicompartment Janus nanoparticles and, combined with SAXS data, confirmed the presence of mixed cubic phases and mixed cubic/hexagonal phases within individual nanoparticles. We further investigated computer visualization models to interpret the potential interface between the interconnected coexisting nanostructured domains within a single nanoparticle. PMID:25984944

  17. Direct torsion control of flexible shaft in an observer-based discrete-time sliding mode

    Microsoft Academic Search

    P. Koronki; H. Hashimoto; V. Utkin

    1998-01-01

    This paper presents a new speed control method for a two-mass system coupled by a flexible shaft. Two control loops are proposed; the outer angular speed control loop calculates the reference signal for the inner loop, where the torsion of the shaft is handled as a variable under control. In this paper, the observer-based discrete-time sliding-mode (ODSM) control implementation and

  18. Direct observation of liquid-phase sintering in the system tungsten carbide-cobalt

    Microsoft Academic Search

    Leonard Froschauer; Richard M. Fulrath

    1976-01-01

    The hot-stage of a scanning electron microscope has been used to observe liquid-phase sintering in the system tungsten carbide-cobalt.\\u000a Densification behaviour and the mechanism for the first, fast stage of sintering have been determined; the influence of particle\\u000a size and the amount of liquid phase has been investigated. In all samples the densification kinetics is that of a rearrangement\\u000a process;

  19. Nature of the clinical difficulties of first-year family medicine residents under direct observation.

    PubMed Central

    Beaumier, A; Bordage, G; Saucier, D; Turgeon, J

    1992-01-01

    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. PMID:1737313

  20. Direct observation of a "devil's staircase'' in wave-particle interaction

    E-print Network

    Fabrice Doveil; Alessandro Macor; Yves Elskens

    2006-04-20

    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 Travelling 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.

  1. Direct observation of a 'devil's staircase' in wave-particle interaction

    SciTech Connect

    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

    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.

  2. Paul trapping of radioactive 6He+ions and direct observation of their beta-decay

    E-print Network

    X. Flechard; E. Lienard; A. Mery; D. Rodriguez; G. Ban; D. Durand; F. Duval; M. Herbane; M. Labalme; F. Mauger; O. Naviliat-Cuncic; J. C. Thomas; Ph. Velten

    2008-10-10

    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.

  3. Direct Observation of Multiferroic Vortex Domains in YMnO3

    PubMed Central

    Zhang, Qinghua; Tan, Guotai; Gu, Lin; Yao, Yuan; Jin, Changqing; Wang, Yanguo; Duan, Xiaofeng; Yu, Richeng

    2013-01-01

    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

  4. High-temperature corrosion observed in austenitic coils and tubes in a direct reduction process

    NASA Astrophysics Data System (ADS)

    Campillo, B.; Gonzales, C.; Hernandez-Duque, G.; Juarez-Islas, J. A.

    2000-02-01

    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.

  5. Direct observation of surface diffusion of large organic molecules at metal surfaces: PVBA on Pd(110)

    NASA Astrophysics Data System (ADS)

    Weckesser, Jens; Barth, Johannes V.; Kern, Klaus

    1999-03-01

    The bonding and surface diffusion of 4-trans-2-(pyrid-4-yl-vinyl) benzoic acid (PVBA) on Pd(110) was investigated by variable temperature scanning tunneling microscopy at sample temperatures between 300 and 450 K. PVBA is a large organic molecule designed for nonlinear optics applications. At low coverages single PVBA molecules are randomly distributed at the surface where they bind diagonally to three neighboring Pd-rows, leading to four equivalent adsorption configurations. The "dog-bone" molecular structure could be resolved. The molecules' surface diffusion is strictly one-dimensional along the close-packed [11¯0]-direction of the surface Pd atomic rows and obeys an Arrhenius law with an activation barrier of 0.83±0.03 eV and an attempt frequency of 1010.3±0.4 s-1.

  6. Direct observation of the decay of first excited Hoyle state in $^{12}$C

    E-print Network

    T. K. Rana; S. Bhattacharya; C. Bhattacharya; S. Kundu; K. Banerjee; T. K. Ghosh; G. Mukherjee; R. Pandey; M. Gohil; A. Dey; J. K. Meena; G. Prajapati; P. Roy; H. Pai; M. Biswas

    2012-03-15

    An excited state of $^{12}$C having excitation energy E$_x \\sim$ 9.65 $\\pm$ 0.02 MeV and width (FWHM) $\\sim607\\pm$ 55 keV, which decays to three $ \\alpha $-particles via Hoyle state ($E_x \\sim$ 7.65 MeV), has been directly identified for the first time in the exclusive inelastic scattering of 60 MeV $^{4}$He on $^{12}$C, measured in coincidence with the recoiling $^{12}$C$ ^* $ Hoyle state (decaying mostly as $^{12}$C$ ^* $ $\\rightarrow \\ ^{8} $Be + $ \\alpha $ $\\rightarrow \\ \\alpha + \\alpha + \\alpha$) by event-by-event kinematic reconstruction of the completely detected (4$ \\alpha $) events. This state is likely to be a candidate for 2$_2^+$ first excited Hoyle state, the existence of which has recently been indirectly evidenced from the recent inclusive inelastic scattering studies.

  7. Direct atomic-scale observation of layer-by-layer oxide growth during magnesium oxidation

    SciTech Connect

    Zheng, He; Wu, Shujing; Sheng, Huaping; Liu, Chun; Liu, Yu; Cao, Fan; Zhou, Zhichao; Zhao, Dongshan, E-mail: wang@whu.edu.cn, E-mail: dszhao@whu.edu.cn; Wang, Jianbo, E-mail: wang@whu.edu.cn, E-mail: dszhao@whu.edu.cn [School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072 (China); Zhao, Xingzhong [School of Physics and Technology, Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, Wuhan University, Wuhan 430072 (China)

    2014-04-07

    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.

  8. Direct observation of the oxygen isotope effect on the in-plane magnetic field penetration depth in optimally doped YBa2Cu3O7-delta.

    PubMed

    Khasanov, R; Eshchenko, D G; Luetkens, H; Morenzoni, E; Prokscha, T; Suter, A; Garifianov, N; Mali, M; Roos, J; Conder, K; Keller, H

    2004-02-01

    We report the first direct observation of the oxygen-isotope ((16)O/(18)O) effect on the in-plane penetration depth lambda(ab) in a nearly optimally doped YBa(2)Cu(3)O(7-delta) film using the novel low-energy muon-spin rotation technique. Spin-polarized low-energy muons are implanted in the film at a known depth z beneath the surface and process in the local magnetic field B(z). This feature allows us to measure directly the profile B(z) of the magnetic field inside the superconducting film in the Meissner state and to make a straightforward determination of lambda(ab). A substantial isotope shift Delta lambda(ab)/lambda(ab)=2.8(1.0)% at 4 K is observed, implying that the in-plane effective supercarrier mass m*(ab) is oxygen-isotope dependent with Delta m*(ab)/m*(ab)=5.5(2.0)%. These results are in good agreement with magnetization measurements on powder samples. PMID:14995343

  9. Direct observation of depth profile of magnetic moment by magnetic circular dichroism

    NASA Astrophysics Data System (ADS)

    Mun, Bongjin Simon; Yang, See-Hun; Mannella, Norman; Kay, Alex W.; Kim, Sang-Koog; Kortright, Jeffrey B.; Underwood, Jim H.; Hussain, Zahid; Fadley, Charles S.

    2001-03-01

    The magnetic properties at the interface between Fe and Cr wedge layers are investigated with a new depth-resolved soft x-ray photoemission spectroscopy (SXPS)[1], combined with magnetic circular dichroism (MCD). The layers of Fe (10 A)/ Cr (50 A wedge- shaped) are grown on a periodic multilayer (B 4 C(22.5A)/W(17.1 A)) _40, which provides the strong standing wave effects of 40 The unique angular dependence of photoelectron intensity of Fe and Cr has been observed at each different Cr wedge thickness and show excellent agreement with the theoretical calculation. To maximize the enhancement and contrast of standing wave effect inside of sample, the sample position is tuned to the Bragg angle position, at which the MCD measurement with SXPS along the different thickness of Cr wedge layer provides the depth profile of the magnetic moment of Fe and Cr. A strong antiparallel coupling across the interface of Cr magnetic moment is clearly resolved while the apparent reduction of Fe magnetic moment is observed near the interface. This observation is consistent with the other works on the same system [2] and even describes how the magnetic moment behaves inside of the sample from the top surface to the interface in one single sample preparation. In this experiment, a new depth-resolved SXPS has been successfully implemented to magnetic multilayer system and prove to be powerful technique to study the buried interface of magnetic system, as proposed by our former work [1]. [1] S.-H. Yang, B. S. Mun, A.W. Kay, S.-K. Kim, J. B. Kortright , J.H. Underwood, Z. Hussain, C. S. Fadley, Surf. Sci. 461 L557-L564 (2000) [2] G. Panaccione, F. Sirotti, E. Narducci, and G. Rossi, Phys. Rev. B 55, 389 (1997)

  10. Artemisinin combination therapy can result in clinical failure if oral therapy is not directly observed

    PubMed Central

    Chan, Wilson W; Virmani, Divya; Pillai, Dylan R

    2013-01-01

    Intravenous artesunate therapy is the first-line therapy for severe malaria, and is highly efficacious when used in combination with an oral partner drug such as doxycycline or atovaquone-proguanil. However, treatment failure occurs routinely with artesunate monotherapy due to the very short half-life of this drug. In North America, experience with artesunate is limited. With the pressure to discharge patients early, administration of the essential oral partner drug is often left to the discretion of the patient. Thus, treatment failure may be commonplace if nonadherence is a factor, as was observed in the case described in the present report. PMID:24489564

  11. Direct Observation of Nanocrystallite Buckling in Carbon Fibers under Bending Load

    SciTech Connect

    Loidl, D.; Peterlik, H. [Institute of Materials Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna (Austria); Paris, O. [Department of Biomaterials, Max-Planck-Institute of Colloids and Interfaces, 14424 Potsdam (Germany); Burghammer, M.; Riekel, C. [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, B.P. 220, F-38043 Grenoble Cedex 9 (France)

    2005-11-25

    Single carbon fibers are deformed in bending by forming loops with varying radius. Position-resolved x-ray diffraction patterns from the bent fibers are collected from the tension to the compression region with a synchrotron radiation nanobeam of 100 nm size from a waveguide structure. A strain redistribution with a shift of the neutral axis is observed. A significant increase of the misorientation of the graphene sheets in the compression region shows that intense buckling of the nanosized carbon crystallites is the physical origin of different tensile and compressive properties.

  12. Direct observation of molecular arrays in the organized smooth endoplasmic reticulum

    E-print Network

    Korkhov, Vladimir M; Zuber, Benoit

    2009-08-24

    of the membranes relative to the section plane was strongly deviating from 90°, as well as the areas where the specimen was severely damaged by freezing and cryo-sectioning procedures (e.g. where crys- talline ice and/or crevasses were observed). Selected regions... sections revealed quasi- crystalline arrays of cadherin molecules connecting the skin cells [25,43]. We propose a model whereby OSER membranes are stabilized in a similar way, i.e., adjacent ER membranes are connected by extended arrays of intra- cellular...

  13. Singlet fission in rubrene single crystal: direct observation by femtosecond pump-probe spectroscopy.

    PubMed

    Ma, Lin; Zhang, Keke; Kloc, Christian; Sun, Handong; Michel-Beyerle, Maria E; Gurzadyan, Gagik G

    2012-06-21

    The excited state dynamics of rubrene in solution and in the single crystal were studied by femtosecond pump-probe spectroscopy under various excitation conditions. Singlet fission was demonstrated to play a predominant role in the excited state relaxation of the rubrene crystal in contrast to rubrene in solution. Upon 500 nm excitation, triplet excitons form on the picosecond time scale via fission from the lowest excited singlet state. Upon 250 nm excitation, fission from upper excited singlet states is observed within 200 fs. PMID:22510785

  14. Hydrogen porosity in directional solidified aluminum-copper alloys: In situ observation

    SciTech Connect

    Lee, P.D.; Hunt, J.D. [Univ. of Oxford (United Kingdom). Dept. of Materials] [Univ. of Oxford (United Kingdom). Dept. of Materials

    1997-10-01

    Using a temperature gradient stage and real time micro-focus radiography the formation of porosity was observed in situ during the solidification of aluminum-copper alloys. Pore morphology was characterized both in the final structure and as a function of temperature during solidification, providing a qualitative insight into the relative importance of the competing physical processes. The effect of solidification velocity, thermal gradient and alloy composition on both the growth kinetics and final structure of the porosity was quantified. Statistical analysis was used to compare the trends in these results to both diffusion controlled and shrinkage driven pore growth.

  15. Direct and instantaneous observation of intravenously injected substances using intravital confocal micro-videography.

    PubMed

    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

    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

  16. Direct observation of stepped proteolipid ring rotation in E. coli FoF1-ATP synthase

    PubMed Central

    Ishmukhametov, Robert; Hornung, Tassilo; Spetzler, David; Frasch, Wayne D

    2010-01-01

    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°. PMID:21037553

  17. Direct observation of a borane–silane complex involved in frustrated Lewis-pair-mediated hydrosilylations

    NASA Astrophysics Data System (ADS)

    Houghton, Adrian Y.; Hurmalainen, Juha; Mansikkamäki, Akseli; Piers, Warren E.; Tuononen, Heikki M.

    2014-11-01

    Perfluorarylborane Lewis acids catalyse the addition of silicon–hydrogen bonds across C=C, C=N and C=O double bonds. This ‘metal-free’ hydrosilylation has been proposed to occur via borane activation of the silane Si–H bond, rather than through classical Lewis acid/base adducts with the substrate. However, the key borane/silane adduct had not been observed experimentally. Here it is shown that the strongly Lewis acidic, antiaromatic 1,2,3-tris(pentafluorophenyl)-4,5,6,7-tetrafluoro-1-boraindene forms an observable, isolable adduct with triethylsilane. The equilibrium for adduct formation was studied quantitatively through variable-temperature NMR spectroscopic investigations. The interaction of the silane with the borane occurs through the Si–H bond, as evidenced by trends in the Si–H coupling constant and the infrared stretching frequency of the Si–H bond, as well as by X-ray crystallography and theoretical calculations. The adduct's reactivity with nucleophiles demonstrates conclusively the role of this species in metal-free ‘frustrated-Lewis-pair’ hydrosilylation reactions.

  18. Electron impact ionization in Saturn's magnetosphere: Direct calculations using observed, nonthermal electron distributions

    NASA Astrophysics Data System (ADS)

    Crary, Frank; Holmberg, Mika; Wahlund, Jan-Erik; Coates, Andrew; Delamere, Peter; Taylor, Sam

    2015-04-01

    The primary source of ions in Saturn's magnetosphere is electron impact ionizaton of neutral water molecules from Enceladus. Charge exchange does not produce a net increase in ion density. Photoionization, at a rate of less than 5x10-9 s-1, is believed to be less significant than electron impact. Existing estimates of the electron impact ionization rate have either been based on observed electron temperatures (much less than 10 eV near L=6) or models of physical chemistry. The later require a hot electron component to produce an ionization rate sufficient to match other data. Since the threshold for ionizationion is 13 eV and the cross section peaks around 100 eV, essentially all ionization is a result of the non-thermal tail on the electron distribtion. To fully account for this, we numerically integrate the full electron spectrum observed by the Cassini/CAPS-ELS instrument and the ionization cross section. The resulting ionization rates, as a function of spacecraft L shell, latitude and local time are compared with previous estimates and models.

  19. Evidence for direct CP violation in B±??h± and observation of B0??K0.

    PubMed

    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

    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

  20. Directly observed reductive elimination of aryl halides from monomeric arylpalladium(II) halide complexes.

    PubMed

    Roy, Amy H; Hartwig, John F

    2003-11-19

    Monomeric, three-coordinate arylpalladium(II) halide complexes undergo reductive elimination of aryl halide to form free haloarene and Pd(0). Reductive elimination of aryl chlorides, bromides, and iodides were observed upon the addition of P(t-Bu)3 to Pd[P(t-Bu)3](Ar)(X) (X = Cl, Br, I). Conditions to observe the equilibrium between reductive elimination and oxidative addition were established with five haloarenes. Reductive elimination of aryl chloride was most favored thermodynamically, and elimination of aryl iodide was the least favored. However, reductive elimination from the aryl chloride complex was the slowest, and reductive elimination from the aryl bromide complex was the fastest. These data show that the electronic properties of the halide, not the thermodynamic driving force for the addition of elimination reaction, control the rates for addition and elimination of haloarenes. Mechanistic data suggest that reversible reductive elimination of aryl bromide to form Pd[P(t-Bu)3] and free aryl bromide is followed by rate-limiting coordination of P(t-Bu)3 to form Pd[P(t-Bu)3]2. PMID:14611215

  1. The lipoamide dehydrogenase from Mycobacterium tuberculosis permits the direct observation of flavin intermediates in catalysis.

    PubMed

    Argyrou, Argyrides; Blanchard, John S; Palfey, Bruce A

    2002-12-10

    Lipoamide dehydrogenase catalyses the NAD(+)-dependent oxidation of the dihydrolipoyl cofactors that are covalently attached to the acyltransferase components of the pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, and glycine reductase multienzyme complexes. It contains a tightly, but noncovalently, bound FAD and a redox-active disulfide, which cycle between the oxidized and reduced forms during catalysis. The mechanism of reduction of the Mycobacterium tuberculosis lipoamide dehydrogenase by NADH and [4S-(2)H]-NADH was studied anaerobically at 4 degrees C and pH 7.5 by stopped-flow spectrophotometry. Three phases of enzyme reduction were observed. The first phase, characterized by a decrease in absorbance at 400-500 nm and an increase in absorbance at 550-700 nm, was fast (k(for) = 1260 s(-)(1), k(rev) = 590 s(-)(1)) and represents the formation of FADH(2).NAD(+), an intermediate that has never been observed before in any wild-type lipoamide dehydrogenase. A primary deuterium kinetic isotope effect [(D)(k(for) + k(rev)) approximately 4.2] was observed on this phase. The second phase, characterized by regain of the absorbance at 400-500 nm, loss of the 550-700 nm absorbance, and gain of 500-550 nm absorbance, was slower (k(obs) = 200 s(-)(1)). This phase represents the intramolecular transfer of electrons from FADH(2) to the redox-active disulfide to generate the anaerobically stable two-electron reduced enzyme, EH(2). The third phase, characterized by a decrease in absorbance at 400-550 nm, represents the formation of the four-electron reduced form of the enzyme, EH(4). The observed rate constant for this phase showed a decreasing NADH concentration dependence, and results from the slow (k(for) = 57 s(-)(1), k(rev) = 128 s(-)(1)) isomerization of EH(2) or slow release of NAD(+) before rapid NADH binding and reaction to form EH(4). The mechanism of oxidation of EH(2) by NAD(+) was also investigated under the same conditions. The 530 nm charge-transfer absorbance of EH(2) shifted to 600 nm upon NAD(+) binding in the dead time of mixing of the stopped-flow instrument and represents formation of the EH(2).NAD(+) complex. This was followed by two phases. The first phase (k(obs) = 750 s(-)(1)), characterized by a small decrease in absorbance at 435 and 458 nm, probably represents limited accumulation of FADH(2).NAD(+). The second phase was characterized by an increase in absorbance at 435 and 458 nm and a decrease in absorbance at 530 and 670 nm. The observed rate constant that describes this phase of approximately 115 s(-)(1) probably represents the overall rate of formation of E(ox) and NADH from EH(2) and NAD(+), and is largely determined by the slower rates of the coupled sequence of reactions preceding flavin oxidation. PMID:12463758

  2. Direct observation of enhanced emission sites in nitrogen implanted hybrid structured ultrananocrystalline diamond films

    SciTech Connect

    Panda, Kalpataru; Sundaravel, B.; Panigrahi, B. K. [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Chen, Huang-Chin; Lin, I.-Nan [Department of Physics, Tamkang University, New-Taipei 251, Taiwan (China)

    2013-02-07

    A hybrid-structured ultrananocrystalline diamond (h-UNCD) film, synthesized on Si-substrates by a two-step microwave plasma enhanced chemical vapour deposition (MPECVD) process, contains duplex structure with large diamond aggregates evenly dispersed in a matrix of ultra-small grains ({approx}5 nm). The two-step plasma synthesized h-UNCD films exhibit superior electron field emission (EFE) properties than the one-step MPECVD deposited UNCD films. Nitrogen-ion implantation/post-annealing processes further improve the EFE properties of these films. Current imaging tunnelling spectroscopy in scanning tunnelling spectroscopy mode directly shows increased density of emission sites in N implanted/post-annealed h-UNCD films than as-prepared one. X-ray photoelectron spectroscopy measurements show increased sp{sup 2} phase content and C-N bonding fraction in N ion implanted/post-annealed films. Transmission electron microscopic analysis reveals that the N implantation/post-annealing processes induce the formation of defects in the diamond grains, which decreases the band gap and increases the density of states within the band gap of diamond. Moreover, the formation of nanographitic phase surrounding the small diamond grains enhanced the conductivity at the diamond grain boundaries. Both of the phenomena enhance the EFE properties.

  3. Direct observation of field-injected space charge in a metal-insulator-metal structure

    SciTech Connect

    Anderson, R.A.; Kurtz, S.R.

    1984-11-15

    An experimental technique has been developed for measuring space charge in dielectric films, which employs a stress wave that is generated thermoelastically from the absorption of a subnanosecond laser pulse. Spatial resolution in the thickness direction approaching one micron is attainable through a deconvolution procedure, and the sensitivity to areal charge density is about 10 ..mu..C/m/sup 2/. The method is sufficient to resolve the distribution of field-injected charge in films of oriented poly(ethylene terephthalate) which were electrically stressed at room temperature. Concentrations of charge are found within a few microns of either electrode but lesser amounts extend deeply into the dielectric. Enough charge is measured after stressing specimens near breakdown to have reduced the field at the negative electrode by as much as 10% during the period of stress. The gradual decay of injected charge over a period of many days is found to be consistent with a spatially uniform, ohmic conductivity which follows a simple, inverse power law of elapsed time.

  4. Direct observation of grafting interlayer phosphate in Mg/Al layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Shimamura, Akihiro; Kanezaki, Eiji; Jones, Mark I.; Metson, James B.

    2012-02-01

    The grafting of interlayer phosphate in synthetic Mg/Al layered double hydroxides with interlayer hydrogen phosphate (LDH-HPO4) has been studied by XRD, TG/DTA, FT-IR, XPS and XANES. The basal spacing of crystalline LDH-HPO4 decreases in two stages with increasing temperature, from 1.06 nm to 0.82 nm at 333 K in the first transition, and to 0.722 nm at 453 K in the second. The first stage occurs due to the loss of interlayer water and rearrangement of the interlayer HPO42-. In the second transition, the interlayer phosphate is grafted to the layer by the formation of direct bonding to metal cations in the layer, accompanied by a change in polytype of the crystalline structure. The grafted phosphate becomes immobilized and cannot be removed by anion-exchange with 1-octanesulfonate. The LDH is amorphous at 743 K but decomposes to Mg3(PO4)2, AlPO4, MgO and MgAl2O4 after heated to 1273 K.

  5. The direct observation of alkali vapor species in biomass combustion and gasification

    SciTech Connect

    French, R.J.; Dayton, D.C.; Milne, T.A.

    1994-01-01

    This report summarizes new data from screening various feedstocks for alkali vapor release under combustion conditions. The successful development of a laboratory flow reactor and molecular beam, mass spectrometer interface is detailed. Its application to several herbaceous and woody feedstocks, as well as a fast-pyrolysis oil, under 800 and 1,100{degrees}C batch combustion, is documented. Chlorine seems to play a large role in the facile mobilization of potassium. Included in the report is a discussion of relevant literature on the alkali problem in combustors and turbines. Highlighted are the phenomena identified in studies on coal and methods that have been applied to alkali speciation. The nature of binding of alkali in coal versus biomass is discussed, together with the implications for the ease of release. Herbaceous species and many agricultural residues appear to pose significant problems in release of alkali species to the vapor at typical combustor temperatures. These problems could be especially acute in direct combustion fired turbines, but may be ameliorated in integrated gasification combined cycles.

  6. Direct observation of the formation of liquid protrusions on polymer colloids and their coalescence.

    PubMed

    Peng, Bo; van Blaaderen, Alfons; Imhof, Arnout

    2013-05-22

    Monodisperse nonspherical poly (methyl methacrylate) (PMMA) particles where a central core particle had grown two extra "lobes", or protrusions, placed opposite each other were successfully synthesized by swelling and subsequent polymerization of cross-linked PMMA spheres with methyl methacrylate and the cross-linker ethylene glycol dimethacrylate. The use of large (~3 ?m) seed particles allowed for real-time monitoring of the swelling and deswelling of the cross-linked particles with optical microscopy. First, a large number of small droplets of swelling monomers formed simultaneously on the surface of the seed particles, and then fused together until under certain conditions two protrusions remained on opposite sides of the seed particles. The yield of such particles could be made up to 90% with a polydispersity of 7.0%. Stirring accelerated the transfer of the swelling monomers to the seed particles. Stirring was also found to induce self-assembly of the swollen seed particles into a wide variety of n-mers, consisting of a certain number, n, of swollen seed particles. The formation of these structures is guided by the minimization of the interfacial free energy between the seed particles, liquid protrusions and aqueous phase, but stirring time and geometrical factors influence it as well. By inducing polymerization the structures could be made permanent. Some control over the topology as well as overall size of the clusters was achieved by varying the stirring time before polymerization. 3D models of possible particle structures were used to identify all projections of the structures obtained by scanning electron microscopy. These models also revealed that the seed particles inside the central coalesced body were slightly compressed after polymerization. By extending the synthesis of the monodisperse particles with n = 1 to (slightly) different monomers and/or different cores, an important class of patchy particles could be realized. PMID:23594337

  7. Structure of the Antarctic Circumpolar Current in Drake Passage From Direct Velocity Observations

    NASA Astrophysics Data System (ADS)

    Firing, Y. L.; Chereskin, T. K.

    2008-12-01

    The structure of the Antarctic Circumpolar Current (ACC) in the upper 1000~m of Drake Passage is examined using nearly three years of shipboard Acoustic Doppler Current Profiler (SADCP) velocity data from a 38~kHz Ocean Surveyor mounted in the hull of the Antarctic supply vessel ARSV Laurence M. Gould. The principal fronts of the ACC are clearly visible, with the Subantarctic Front (SAF) and Polar Front (PF) jets having widths of about 100~km and 150~km, respectively. Depth-mean current speeds in the SAF and PF jets are ~40~cm~s-1, while the eddy kinetic energy (EKE) has a maximum of ~700~cm2s-2 between the PF and the SAF. Horizontal-wavenumber velocity spectra peak at ~350~km. These numbers are similar to surface-layer values found by Lenn et al. (J. Mar. Res., 2007). The transport estimated from the mean section between the surface and 1030~m is ~100~Sv, or about 70% of the canonical total transport. The extended depth range available from the 38~kHz instrument allows us to investigate the depth structure of the current. The mean current is largely barotropic, while EKE and shear variance exhibit strong depth dependence. In cross-sectional averages current shear is small and nearly constant to 600~m, below which depth the current speed drops off more quickly; mean jet speeds are around 50~cm~s-1 at 46~m (the first depth bin) and 20~cm~s-1 at 1030~m. Various possibilities for a vertical structure function are explored. EKE is intensified above 600~m between the SAF and PF. Shear variance is strongest in the surface layer. Vertical-wavenumber spectra of currents and current shear reveal negligible rotation. Through-passage currents have more energy at the lowest vertical wavenumbers (wavelengths of ~1000~m), while at scales smaller than ~100~m, energy in across-passage currents is greater.

  8. S-Shaped Flow Curves of Shear Thickening Suspensions: Direct Observation of Frictional Rheology

    E-print Network

    Zhongcheng Pan; Henri de Cagny; Bart Weber; Daniel Bonn

    2015-06-03

    We study the rheological behavior of concentrated granular suspensions of simple spherical particles. Under controlled stress, the system exhibits an S-shaped flow curve (stress vs. shear rate) with a negative slope in between the low-viscosity Newtonian regime and the shear thickened regime. Under controlled shear rate, a discontinuous transition between the two states is observed. Stress visualization experiments with a novel fluorescent probe suggest that friction is at the origin of shear thickening. Stress visualization shows that the stress in the system remains homogeneous (no shear banding) if a stress is imposed that is intermediate between the high and low-stress branches. The S-shaped shear thickening is then due to the discontinuous formation of a frictional force network between particles upon increasing the stress.

  9. Direct observation of vacuum fluctuations in a spinor Bose-Einstein condensate

    E-print Network

    Klempt, Carsten; Gebreyesus, Gebremedhn; Scherer, Manuel; Henninger, Thorsten; Hyllus, Philipp; Ertmer, Wolfgang; Santos, Luis; Arlt, Jan

    2009-01-01

    The nature of the vacuum state and its fluctuations constitutes one of the most fascinating aspects of modern physics. Despite their non-intuitive character, vacuum fluctuations play an important role for our understanding of nature. Specifically, the parametric amplification of such fluctuations is crucial for phenomena ranging from optical parametric down-conversion to stimulated positronium annihilation, and boson creation in Universe inflation. Spinor Bose-Einstein condensates, consisting of atoms with non-zero total spin, provide an optimal system for the investigation of the vacuum state, since vacuum fluctuations can dominate classical fluctuations in the spin dynamics of these magnetic superfluids. Here we explore the amplification of vacuum fluctuations in gaseous spinor condensates in an unstable spin configuration. We observe strong instability resonances in the spinor condensate, induced by the confinement of the atomic ensemble. Our work shows that it is crucial for the understanding of spinor dy...

  10. Direct observation of frequency modulated transcription in single cells using light activation

    PubMed Central

    Larson, Daniel R; Fritzsch, Christoph; Sun, Liang; Meng, Xiuhau; Lawrence, David S; Singer, Robert H

    2013-01-01

    Single-cell analysis has revealed that transcription is dynamic and stochastic, but tools are lacking that can determine the mechanism operating at a single gene. Here we utilize single-molecule observations of RNA in fixed and living cells to develop a single-cell model of steroid-receptor mediated gene activation. We determine that steroids drive mRNA synthesis by frequency modulation of transcription. This digital behavior in single cells gives rise to the well-known analog dose response across the population. To test this model, we developed a light-activation technology to turn on a single steroid-responsive gene and follow dynamic synthesis of RNA from the activated locus. DOI: http://dx.doi.org/10.7554/eLife.00750.001 PMID:24069527

  11. Direct observation of interface and nanoscale compositional modulation in ternary III-As heterostructure nanowires

    SciTech Connect

    Venkatesan, Sriram; Scheu, Christina [Department of Chemistry and Center for NanoScience, Ludwig-Maximilians-Universität München, Butenandstr 5-13(E), 81377 München (Germany)] [Department of Chemistry and Center for NanoScience, Ludwig-Maximilians-Universität München, Butenandstr 5-13(E), 81377 München (Germany); Madsen, Morten H.; Krogstrup, Peter; Johnson, Erik [Nano-Science Center and Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen (Denmark)] [Nano-Science Center and Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen (Denmark); Schmid, Herbert [INM-Leibniz Institute for New Materials, 66123 Saarbrücken (Germany)] [INM-Leibniz Institute for New Materials, 66123 Saarbrücken (Germany)

    2013-08-05

    Straight, axial InAs nanowire with multiple segments of Ga{sub x}In{sub 1?x}As was grown. High resolution X-ray energy-dispersive spectroscopy (EDS) mapping reveals the distribution of group III atoms at the axial interfaces and at the sidewalls. Significant Ga enrichment, accompanied by a structural change is observed at the Ga{sub x}In{sub 1?x}As/InAs interfaces and a higher Ga concentration for the early grown Ga{sub x}In{sub 1?x}As segments. The elemental map and EDS line profile infer Ga enrichment at the facet junctions between the sidewalls. The relative chemical potentials of ternary alloys and the thermodynamic driving force for liquid to solid transition explains the growth mechanisms behind the enrichment.

  12. Direct Observation of Magnetoresistance Variation in Molecular Junctions Induced by Electrode Geometry

    NASA Astrophysics Data System (ADS)

    Fei, Xiangmin; Wu, Guangfen; Lopez, Vanessa; Lu, Gang; Gao, Hong-Jun; Gao, Li

    2015-03-01

    Spin-polarized electron transport in the Co/C60/Co/Ni molecular junctions, in which the fullerene (C60) molecule is in electrical contact with electrodes, has been investigated using an ultra-high vacuum cryogenic scanning tunneling microscope (STM). By combining spin-polarized STM and current-displacement measurements, the spin-polarized contact conductance of molecular junctions has been measured at 5 K. Large tunnel magnetoresistance (TMR) values higher than -60% have been observed. Depending on electrode geometry, the measured TMR values vary by a factor of ~ 1.5. The atomic-scale geometry of the electrode apex strongly impacts the spin-polarization of the electrodes and that of the interfacial hybrid molecular states. Our findings suggest that atomic-scale engineering of electrodes represents a new and effective approach to tuning the magnetotransport in molecular spintronic devices.

  13. New Results from Space and Field Observations on the Aerosol Direct and Indirect Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram J.; Remer, Lorraine; Tanre, Didier; Boucher, Olivier; Chin, Mian; Dubovik, Oleg; Holben, Brent

    2002-01-01

    New space observations from the MODIS instrument on board the Terra satellite and analysis of POLDER data flown on the ADEOS satellite, show in great details the spatial and seasonal variability of the global aerosol system. These spaceborne instruments distinguish fine aerosol from man-made regional pollution and biomass burning from mostly natural coarse dust and sea salt aerosol. E.g. fine regional pollution in and around the Indian sub-continent, Europe and North America; smoke from biomass burning in Southern Africa and Southern America; coarse dust from West Africa and mixed dust pollution and smoke from West and central Africa and East Asia. These regions were also studied extensively in focused field experiments and by the distributed AERONET network. The results generate the first climatologies of the aerosol system, are used to derive the aerosol radiative effects and to estimate the anthropogenic component. The measurements are also used to evaluate each other and constrain aerosol transport models.

  14. Direct observation of catalytic oxidation of particulate matter using in situ TEM

    PubMed Central

    Kamatani, Kohei; Higuchi, Kimitaka; Yamamoto, Yuta; Arai, Shigeo; Tanaka, Nobuo; Ogura, Masaru

    2015-01-01

    The ability to observe chemical reactions at the molecular level convincingly demonstrates the physical and chemical phenomena occurring throughout a reaction mechanism. Videos obtained through in situ transmission electron microscopy (TEM) revealed the oxidation of catalytic soot under practical reaction conditions. Carbon oxidation reactions using Ag/SiO2 or Cs2CO3/nepheline catalysts were performed at 330?°C under an O2 flow of 0.5?Pa in the TEM measurement chamber. Ag/SiO2 catalyzed the reaction at the interface of the mobile Ag species and carbon, while the Cs species was fixed on the nepheline surface during the reaction. In the latter case, carbon particles moved, remained attached to the Cs2CO3/nepheline surface, and were consumed at the interface by the oxidation reaction. Using this technique, we were able to visualize such mobile and immobile catalysis according to different mechanisms. PMID:26154580

  15. Direct observations of the primary state of radiation damage of ion-irradiated tungsten and platinum

    SciTech Connect

    Seidman, D. N.; Current, M. I.; Pramanik, D.; Wei, C. Y.

    1980-07-01

    A brief summary was presented of all the Cornell work on the primary state of radiation damage in ion-irradiated tungsten and platinum. The primary research tool for all this research was the field-ion microscope (FIM); the FIM was ideally suited for this research because of its excellent atomic resolution and the ability to examine the interior of the specimens, as a result of the field-evaporation effect. This paper summarized, in outline form, the following items: (1) the principal experimental quantities determined from the analyses performed on all the individual depleted zones (DZs) observed; (2) the main experimental programs; (3) a number of the more important results and conclusions concerning the vacancy structure of DZs; and (4) the three-dimensional spatial distribution of self-interstitial atoms around DZs in tungsten which had been irradiated and examined in situ at 10/sup 0/K.

  16. Direct Observation of the Phenomenology of a Solid Thermal Explosion Using Time-Resolved Proton Radiography

    SciTech Connect

    Smilowitz, L.; Henson, B. F.; Romero, J. J.; Asay, B. W.; Schwartz, C. L.; Saunders, A.; Merrill, F. E.; Morris, C. L.; Kwiatkowski, K.; Hogan, G.; Nedrow, P.; Murray, M. M.; Thompson, T. N.; McNeil, W.; Rightley, P.; Marr-Lyon, M. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2008-06-06

    We present a new phenomenology for burn propagation inside a thermal explosion based on dynamic radiography. Radiographic images were obtained of an aluminum cased solid cylindrical sample of a plastic bonded formulation of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine. The phenomenology observed is ignition followed by cracking in the solid accompanied by the propagation of a radially symmetric front of increasing proton transmission. This is followed by a further increase in transmission through the sample, ending after approximately 100 {mu}s. We show that these processes are consistent with the propagation of a convective burn front followed by consumption of the remaining solid by conductive particle burning.

  17. Direct Observations of Magnetic Reconnection Outflow and CME Triggering in a Small Erupting Solar Prominence

    NASA Astrophysics Data System (ADS)

    Reeves, Katharine K.; McCauley, Patrick I.; Tian, Hui

    2015-07-01

    We examine a small prominence eruption that occurred on 2014 May 1 at 01:35 UT and was observed by the Interface Region Imaging Spectrometer (IRIS) and the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory. Pre- and post-eruption images were taken by the X-ray Telescope (XRT) on Hinode. Pre-eruption, a dome-like structure exists above the prominence, as demarcated by coronal rain. As the eruption progresses, we find evidence for reconnection between the prominence magnetic field and the overlying field. Fast flows are seen in AIA and IRIS, indicating reconnection outflows. Plane-of-sky flows of 300 km s?1 are observed in the AIA 171 A channel along a potentially reconnected field line. IRIS detects intermittent fast line of sight flows of 200 km s?1 coincident with the AIA flows. Differential emission measure calculations show heating at the origin of the fast flows. Post-eruption XRT images show hot loops probably due to reconfiguration of magnetic fields during the eruption and subsequent heating of plasma in these loops. Although there is evidence for reconnection above the prominence during the eruption, high spatial resolution images from IRIS reveal potential reconnection sites below the prominence. A height–time analysis of the erupting prominence shows a slow initial rise with a velocity of 0.4 km s?1 followed by a rapid acceleration with a final velocity of 250 km s?1. Brightenings in IRIS during the transition between these two phases indicate the eruption trigger for the fast part of the eruption is likely a tether-cutting mechanism rather than a break-out mechanism.

  18. Direct Observation of T4 Lysozyme Hinge-Bending Motion by Fluorescence Correlation Spectroscopy

    PubMed Central

    Yirdaw, Robel B.; Mchaourab, Hassane S.

    2012-01-01

    Bacteriophage T4 Lysozyme (T4L) catalyzes the hydrolysis of the peptidoglycan layer of the bacterial cell wall late in the infection cycle. It has long been postulated that equilibrium dynamics enable substrate access to the active site located at the interface between the N- and C-terminal domains. Crystal structures of WT-T4L and point mutants captured a range of conformations that differ by the hinge-bending angle between the two domains. Evidence of equilibrium between open and closed conformations in solution was gleaned from distance measurements between the two domains but the nature of the equilibrium and the timescale of the underlying motion have not been investigated. Here, we used fluorescence fluctuation spectroscopy to directly detect T4L equilibrium conformational fluctuations in solution. For this purpose, Tetramethylrhodamine probes were introduced at pairs of cysteines in regions of the molecule that undergo relative displacement upon transition from open to closed conformations. Correlation analysis of Tetramethylrhodamine intensity fluctuations reveals hinge-bending motion that changes the relative distance and orientation of the N- and C-terminal domains with ?15 ?s relaxation time. That this motion involves interconversion between open and closed conformations was further confirmed by the dampening of its amplitude upon covalent substrate trapping. In contrast to the prevalent two-state model of T4L equilibrium, molecular brightness and number of particles obtained from cumulant analysis suggest that T4L populates multiple intermediate states, consistent with the wide range of hinge-bending angles trapped in the crystal structure of T4L mutants. PMID:23062345

  19. Quantifying the weight of fingerprint evidence through the spatial relationship, directions and types of minutiae observed on fingermarks.

    PubMed

    Neumann, Cedric; Champod, Christophe; Yoo, Mina; Genessay, Thibault; Langenburg, Glenn

    2015-03-01

    This paper presents a statistical model for the quantification of the weight of fingerprint evidence. Contrarily to previous models (generative and score-based models), our model proposes to estimate the probability distributions of spatial relationships, directions and types of minutiae observed on fingerprints for any given fingermark. Our model is relying on an AFIS algorithm provided by 3M Cogent and on a dataset of more than 4,000,000 fingerprints to represent a sample from a relevant population of potential sources. The performance of our model was tested using several hundreds of minutiae configurations observed on a set of 565 fingermarks. In particular, the effects of various sub-populations of fingers (i.e., finger number, finger general pattern) on the expected evidential value of our test configurations were investigated. The performance of our model indicates that the spatial relationship between minutiae carries more evidential weight than their type or direction. Our results also indicate that the AFIS component of our model directly enables us to assign weight to fingerprint evidence without the need for the additional layer of complex statistical modeling involved by the estimation of the probability distributions of fingerprint features. In fact, it seems that the AFIS component is more sensitive to the sub-population effects than the other components of the model. Overall, the data generated during this research project contributes to support the idea that fingerprint evidence is a valuable forensic tool for the identification of individuals. PMID:25637956

  20. Apollo 11 and 16 Soil Bi-directional Solar Reflectance Measurements, Models and LRO Diviner Observations

    NASA Astrophysics Data System (ADS)

    Foote, E. J.; Paige, D. A.; Shepard, M. K.; Johnson, J. R.; Biggar, S. F.; Greenhagen, B. T.; Allen, C.

    2010-12-01

    We have compared laboratory solar reflectance measurements of Apollo 11 and 16 soil samples to Lunar Reconnaissance Orbiter (LRO) Diviner orbital albedo measurements at the Apollo landing sites. The soil samples are two representative end member samples from the moon, low albedo lunar maria (sample 10084) and high albedo lunar highlands (sample 68810). Bidirectional reflectance distribution function (BRDF) measurements of the soil samples were conducted at Bloomsburg University (BUG) and at the University of Arizona [1,2]. We collected two different types of BUG datasets: a standard set of BRDF measurements at incidence angles of 0-60°, emission angles of 0-80°, and phase angles of 3-140°, and a high-incidence angle set of measurements along and perpendicular to the principal plane at incidence angles of 0-75° and phase angles of 3-155°. The BUG measurements generated a total of 765 data points in four different filters 450, 550, 750 and 950 nm. The Blacklab measurements were acquired at incidence angles of 60-88°, emission angles 60-82°, and phase angles of 17-93° at wavelengths of 455, 554, 699, 949nm. The BUG data were fit to two BRDF models: Hapke’s model [3] as described by Johnson et al, 2010 [4], and a simplified empirical function. The fact that both approaches can satisfactorily fit the BUG data is not unexpected, given the similarities between the functions and their input parameters, and the fact that the BRDF for dark lunar soil is dominated by the single scattering phase functions of the individual soil particles. To compare our lunar sample measurements with LRO Diviner data [5], we selected all daytime observations acquired during the first year of operation within 3 km square boxes centered at the landing sites. We compared Diviner Channel 1 (0.3 - 3 µm) Lambert albedos with model calculated Lambert albedos of the lunar samples at the same photometric angles. In general, we found good agreement between the laboratory and Diviner measurements, particularly at intermediate incidence angles. We are currently reconciling any differences observed between our two datasets to provide mutual validation, and to better understand the Diviner solar reflectance measurements in terms of lunar regolith properties. [1] Shepard, M.K., Solar System Remote Sensing Symposium, #4004, LPI, 2002; [2] Biggar, S.F. et al, Proc. Soc. Photo-Opt. Instrum. Eng. 924:232-240, 1988; [3] Hapke, B. Theory of Reflectance and Emittance Spectroscopy, Cambridge University Press, 1993; [4] Johnson J.R. et al, Fall AGU 2010; [5] Paige, D.A. et al, Space Science Reviews, 150:125-160, 2010;

  1. Direct observation of self-similar contact line depinning from superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Paxson, Adam; Varanasi, Kripa

    2013-11-01

    The adhesion of a drop to a superhydrophobic surface, although very low, is never altogether eliminated. As the drop moves along the surface, the advancing portion of the contact line simply lies down onto the upcoming roughness features, contributing negligibly to adhesion. Instead, the pinning and contact angle hysteresis are governed by the depinning of capillary bridges formed at the receding portion of the contact line. We use environmental scanning electron microscopy to observe these depinning events at the microscale. After measuring the local receding contact angle of capillary bridges formed on a micropillar array, we find that these depinning events follow the Gibbs depinning criterion. We further extend this technique to two-scale hierarchical structures to reveal a self-similar depinning mechanism in which the adhesion of the entire drop depends only on the pinning at the very smallest level of roughness hierarchy. With this self-similar depinning mechanism we develop a model to predict the adhesion of drops to superhydrophobic surfaces that explains both the low adhesion on sparsely structured surfaces and the surprisingly high adhesion on surfaces whose features are densely spaced or tortuously shaped.

  2. Direct observation of the transition state of ultrafast electron transfer reaction of a radiosensitizing drug bromodeoxyuridine

    SciTech Connect

    Wang, C.-R.; Hu, A.; Lu, Q.-B. [Department of Physics, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2006-06-28

    Replacement of thymidine in DNA by bromodeoxyuridine (BrdU) has long been known to enhance DNA damage and cell death induced by ionizing/UV radiation, but the mechanism of action of BrdU at the molecular level is poor understood. Using time-resolved femtosecond laser spectroscopy, we obtain the real-time observation of the transition state of the ultrafast electron transfer (ET) reaction of BrdU with the precursor to the hydrated electron, which is a general product in ionizing/UV radiation. The results show that the ET reaction is completed within 0.2 picosecond (ps) after the electronic excitation, leading to the formation of a transition state BrdU*{sup -} with a lifetime of {approx}1.5 ps that then dissociates into Br{sup -} and a high reactive radical dU{sup *}. The present results can greatly enhance our understanding not only of the mechanism of BrdU as a radio-/photosensitizer but of the role of prehydrated electrons in electron-initiated processes in biological and environmental systems.

  3. Direct observations of the upper layer circulation in the southern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Pérez-Brunius, Paula; García-Carrillo, Paula; Dubranna, Jean; Sheinbaum, Julio; Candela, Julio

    2013-01-01

    The upper layer circulation in the Bay of Campeche is analyzed with three years of data recorded by surface drifters, current meter moorings, and satellite altimetry. The measurements show that the mean cyclonic circulation observed by previous authors extends below 1000 m, and that its size and location are delimited by the particular topography of the region: a deep basin to the west, and a shallower and gentle sloping submarine fan to the east. An Empirical Orthogonal Function analysis and large correlations of the surface flow with the deeper currents suggest that the topographic constraint is the result of potential vorticity conservation for an equivalent barotropic flow. The variability of the surface currents in the western basin is mostly due to changes in the size, form, position and intensity of the cyclonic gyre due to its interaction with northern Gulf of Mexico eddies, particularly Loop Current Eddies traveling the southern route towards the western boundary. By contrast, the eastern basin is characterized by a weak northward drift, with the occasional generation of anticyclones in the southeastern boundary, the genesis of which remains to be understood. This suggests that the variability in the eastern basin is mostly driven by locally generated disturbances, rather than by an influx of northern Gulf of Mexico eddies. Strong northward flows in the central and eastern basins result from the flow convergence between locally generated anticyclones and the cyclonic gyre.

  4. Direct nanoscale observations of the coupled dissolution of calcite and dolomite and the precipitation of gypsum

    PubMed Central

    Cama, Jordi; Soler, Josep Maria; Putnis, Christine V

    2014-01-01

    Summary In-situ atomic force microscopy (AFM) experiments were performed to study the overall process of dissolution of common carbonate minerals (calcite and dolomite) and precipitation of gypsum in Na2SO4 and CaSO4 solutions with pH values ranging from 2 to 6 at room temperature (23 ± 1 °C). The dissolution of the carbonate minerals took place at the (104) cleavage surfaces in sulfate-rich solutions undersaturated with respect to gypsum, by the formation of characteristic rhombohedral-shaped etch pits. Rounding of the etch pit corners was observed as solutions approached close-to-equilibrium conditions with respect to calcite. The calculated dissolution rates of calcite at pH 4.8 and 5.6 agreed with the values reported in the literature. When using solutions previously equilibrated with respect to gypsum, gypsum precipitation coupled with calcite dissolution showed short gypsum nucleation induction times. The gypsum precipitate quickly coated the calcite surface, forming arrow-like forms parallel to the crystallographic orientations of the calcite etch pits. Gypsum precipitation coupled with dolomite dissolution was slower than that of calcite, indicating the dissolution rate to be the rate-controlling step. The resulting gypsum coating partially covered the surface during the experimental duration of a few hours. PMID:25161860

  5. Direct observation of the photodegradation of anthracene and pyrene adsorbed onto mangrove leaves.

    PubMed

    Wang, Ping; Wu, Tun-Hua; Zhang, Yong

    2014-01-01

    An established synchronous fluorimetry method was used for in situ investigation of the photodegradation of pyrene (PYR) and anthracene (ANT) adsorbed onto fresh leaves of the seedlings of two mangrove species, Aegiceras corniculatum (L.) Blanco (Ac) and Kandelia obovata (Ko) in multicomponent mixtures (mixture of the ANT and PYR). Experimental results indicated that photodegradation was the main transformation pathway for both ANT and PYR in multicomponent mixtures. The amount of the PAHs volatilizing from the leaf surfaces and entering the inner leaf tissues was negligible. Over a certain period of irradiation time, the photodegradation of both PYR and ANT adsorbed onto the leaves of Ac and Ko followed first-order kinetics, with faster rates being observed on Ac leaves. In addition, the photodegradation rate of PYR on the leaves of the mangrove species in multicomponent mixtures was much slower than that of adsorbed ANT. Compared with the PAHs adsorbed as single component, the photodegradation rate of ANT adsorbed in multicomponent mixtures was slower, while that of PYR was faster. Moreover, the photodegradation of PYR and ANT dissolved in water in multicomponent mixtures was investigated for comparison. The photodegradation rate on leaves was much slower than in water. Therefore, the physical-chemical properties of the substrate may strongly influence the photodegradation rate of adsorbed PAHs. PMID:25144741

  6. Direct evidence for chromospheric evaporation in a well-observed compact flare

    NASA Technical Reports Server (NTRS)

    Canfield, R. C.; Gunkler, T. A.; Hudson, H. S.; Acton, L. W.; Leibacher, J. W.; Kiplinger, A. L.

    1982-01-01

    Observations of the solar flare of May 7, 1980 using several Solar Maximum Mission instruments are presented as an investigation of the phenomenon of chromospheric evaporation. The total amount of plasma at temperatures greater than 2 x 10 to the 6th K were determined from the X-ray data, and the amount of plasma that was evaporated from the chromosphere was determined from the H-alpha data. The H-alpha profiles indicate that for the flare as a whole, at the time of peak soft X-ray emission measure, the number of atoms evaporated from the chromosphere was 7 x 10 to the 37th. The soft X-ray emission measure of 1 x 10 to the 49th/cu cm, coupled with the flare volume estimate of 10 to the 26th cu cm, indicates that there were 3 x 10 to the 37th electrons in the soft X-ray plasma with temperatures greater than 2 x 10 to the 6th K. These results indicate that enough material had been evaporated from the chromosphere to account for the X-ray plasma. Taken together, the H-alpha, soft X-ray, and hard X-ray images indicate that chromospheric evaporation is driven both by flare-accelerated electrons during the impulsive phase and by conduction during the thermal phase.

  7. Observation of direct-photon collective flow in sqrt(s_NN)=200 GeV Au+Au collisions

    E-print Network

    A. Adare; S. Afanasiev; C. Aidala; N. N. Ajitanand; Y. Akiba; H. Al-Bataineh; J. Alexander; K. Aoki; Y. Aramaki; E. T. Atomssa; R. Averbeck; T. C. Awes; B. Azmoun; V. Babintsev; M. Bai; G. Baksay; L. Baksay; K. N. Barish; B. Bassalleck; A. T. Basye; S. Bathe; V. Baublis; C. Baumann; A. Bazilevsky; S. Belikov; R. Belmont; R. Bennett; A. Berdnikov; Y. Berdnikov; A. A. Bickley; J. S. Bok; K. Boyle; M. L. Brooks; H. Buesching; V. Bumazhnov; G. Bunce; S. Butsyk; C. M. Camacho; S. Campbell; C. -H. Chen; C. Y. Chi; M. Chiu; I. J. Choi; R. K. Choudhury; P. Christiansen; T. Chujo; P. Chung; O. Chvala; V. Cianciolo; Z. Citron; B. A. Cole; M. Connors; P. Constantin; M. Csanád; T. Csörg?; T. Dahms; S. Dairaku; I. Danchev; K. Das; A. Datta; G. David; A. Denisov; A. Deshpande; E. J. Desmond; O. Dietzsch; A. Dion; M. Donadelli; O. Drapier; A. Drees; K. A. Drees; J. M. Durham; A. Durum; D. Dutta; S. Edwards; Y. V. Efremenko; F. Ellinghaus; T. Engelmore; A. Enokizono; H. En'yo; S. Esumi; B. Fadem; D. E. Fields; M. Finger; M. Finger Jr.; F. Fleuret; S. L. Fokin; Z. Fraenkel; J. E. Frantz; A. Franz; A. D. Frawley; K. Fujiwara; Y. Fukao; T. Fusayasu; I. Garishvili; A. Glenn; H. Gong; M. Gonin; Y. Goto; R. Granier de Cassagnac; N. Grau; S. V. Greene; M. Grosse Perdekamp; T. Gunji; H. -Å. Gustafsson; J. S. Haggerty; K. I. Hahn; H. Hamagaki; J. Hamblen; R. Han; J. Hanks; E. P. Hartouni; E. Haslum; R. Hayano; X. He; M. Heffner; T. K. Hemmick; T. Hester; J. C. Hill; M. Hohlmann; W. Holzmann; K. Homma; B. Hong; T. Horaguchi; D. Hornback; S. Huang; T. Ichihara; R. Ichimiya; J. Ide; Y. Ikeda; K. Imai; M. Inaba; D. Isenhower; M. Ishihara; T. Isobe; M. Issah; A. Isupov; D. Ivanischev; B. V. Jacak; J. Jia; J. Jin; B. M. Johnson; K. S. Joo; D. Jouan; D. S. Jumper; F. Kajihara; S. Kametani; N. Kamihara; J. Kamin; J. H. Kang; J. Kapustinsky; K. Karatsu; D. Kawall; M. Kawashima; A. V. Kazantsev; T. Kempel; A. Khanzadeev; K. M. Kijima; B. I. Kim; D. H. Kim; D. J. Kim; E. Kim; E. J. Kim; S. H. Kim; Y. J. Kim; E. Kinney; K. Kiriluk; Á. Kiss; E. Kistenev; L. Kochenda; B. Komkov; M. Konno; J. Koster; D. Kotchetkov; A. Kozlov; A. Král; A. Kravitz; G. J. Kunde; K. Kurita; M. Kurosawa; Y. Kwon; G. S. Kyle; R. Lacey; Y. S. Lai; J. G. Lajoie; A. Lebedev; D. M. Lee; J. Lee; K. Lee; K. B. Lee; K. S. Lee; M. J. Leitch; M. A. L. Leite; E. Leitner; B. Lenzi; X. Li; P. Liebing; L. A. Linden Levy; T. Liška; A. Litvinenko; H. Liu; M. X. Liu; B. Love; R. Luechtenborg; D. Lynch; C. F. Maguire; Y. I. Makdisi; A. Malakhov; M. D. Malik; V. I. Manko; E. Mannel; Y. Mao; H. Masui; F. Matathias; M. McCumber; P. L. McGaughey; N. Means; B. Meredith; Y. Miake; A. C. Mignerey; P. Mikeš; K. Miki; A. Milov; M. Mishra; J. T. Mitchell; A. K. Mohanty; Y. Morino; A. Morreale; D. P. Morrison; T. V. Moukhanova; J. Murata; S. Nagamiya; J. L. Nagle; M. Naglis; M. I. Nagy; I. Nakagawa; Y. Nakamiya; T. Nakamura; K. Nakano; J. Newby; M. Nguyen; R. Nouicer; A. S. Nyanin; E. O'Brien; S. X. Oda; C. A. Ogilvie; M. Oka; K. Okada; Y. Onuki; A. Oskarsson; M. Ouchida; K. Ozawa; R. Pak; V. Pantuev; V. Papavassiliou; I. H. Park; J. Park; S. K. Park; W. J. Park; S. F. Pate; H. Pei; J. -C. Peng; H. Pereira; V. Peresedov; D. Yu. Peressounko; C. Pinkenburg; R. P. Pisani; M. Proissl; M. L. Purschke; A. K. Purwar; H. Qu; J. Rak; A. Rakotozafindrabe; I. Ravinovich; K. F. Read; K. Reygers; V. Riabov; Y. Riabov; E. Richardson; D. Roach; G. Roche; S. D. Rolnick; M. Rosati; C. A. Rosen; S. S. E. Rosendahl; P. Rosnet; P. Rukoyatkin; P. Ruži?ka; B. Sahlmueller; N. Saito; T. Sakaguchi; K. Sakashita; V. Samsonov; S. Sano; T. Sato; S. Sawada; K. Sedgwick; J. Seele; R. Seidl; A. Yu. Semenov; R. Seto; D. Sharma; I. Shein; T. -A. Shibata; K. Shigaki; M. Shimomura; K. Shoji; P. Shukla; A. Sickles; C. L. Silva; D. Silvermyr; C. Silvestre; K. S. Sim; B. K. Singh; C. P. Singh; V. Singh; M. Slune?ka; R. A. Soltz; W. E. Sondheim; S. P. Sorensen; I. V. Sourikova; N. A. Sparks; P. W. Stankus; E. Stenlund; S. P. Stoll; T. Sugitate; A. Sukhanov; J. Sziklai; E. M. Takagui; A. Taketani; R. Tanabe; Y. Tanaka; K. Tanida; M. J. Tannenbaum; S. Tarafdar; A. Taranenko; P. Tarján; H. Themann; T. L. Thomas; M. Togawa; A. Toia; L. Tomášek; H. Torii; R. S. Towell; I. Tserruya; Y. Tsuchimoto; C. Vale; H. Valle; H. W. van Hecke; E. Vazquez-Zambrano; A. Veicht; J. Velkovska; R. Vértesi; A. A. Vinogradov; M. Virius; V. Vrba; E. Vznuzdaev; X. R. Wang; D. Watanabe; K. Watanabe; Y. Watanabe; F. Wei; R. Wei; J. Wessels; S. N. White; D. Winter; J. P. Wood; C. L. Woody; R. M. Wright; M. Wysocki; W. Xie; Y. L. Yamaguchi; K. Yamaura; R. Yang; A. Yanovich; J. Ying; S. Yokkaichi; Z. You; G. R. Young; I. Younus; I. E. Yushmanov; W. A. Zajc; C. Zhang; S. Zhou; L. Zolin

    2011-08-22

    The second Fourier component v_2 of the azimuthal anisotropy with respect to the reaction plane was measured for direct photons at midrapidity and transverse momentum (p_T) of 1--13 GeV/c in Au+Au collisions at sqr(s_NN)=200 GeV. Previous measurements of this quantity for hadrons with p_T 6 GeV/c a reduced anisotropy is interpreted in terms of a path-length dependence for parton energy loss. In this measurement with the PHENIX detector at the Relativistic Heavy Ion Collider we find that for p_T > 4 GeV/c the anisotropy for direct photons is consistent with zero, as expected if the dominant source of direct photons is initial hard scattering. However, in the p_T < 4 GeV/c region dominated by thermal photons, we find a substantial direct photon v_2 comparable to that of hadrons, whereas model calculations for thermal photons in this kinematic region significantly underpredict the observed v_2.

  8. Observation of Direct-Photon Collective Flow in Au+Au Collisions at sNN=200GeV

    NASA Astrophysics Data System (ADS)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Bataineh, H.; Alexander, J.; Aoki, K.; Aramaki, Y.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Baksay, G.; Baksay, L.; Barish, K. N.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Baublis, V.; Baumann, C.; Bazilevsky, A.; Belikov, S.; Belmont, R.; Bennett, R.; Berdnikov, A.; Berdnikov, Y.; Bickley, A. A.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Camacho, C. M.; Campbell, S.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chung, P.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Connors, M.; Constantin, P.; Csanád, M.; Csörg?, T.; Dahms, T.; Dairaku, S.; Danchev, I.; Das, K.; Datta, A.; David, G.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; Dutta, D.; Edwards, S.; Efremenko, Y. V.; Ellinghaus, F.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M., Jr.; Fleuret, F.; Fokin, S. L.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fusayasu, T.; Garishvili, I.; Glenn, A.; Gong, H.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Gustafsson, H.-Å.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Han, R.; Hanks, J.; Hartouni, E. P.; Haslum, E.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hohlmann, M.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Ide, J.; Ikeda, Y.; Imai, K.; Inaba, M.; Isenhower, D.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Ivanischev, D.; Jacak, B. V.; Jia, J.; Jin, J.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kang, J. H.; Kapustinsky, J.; Karatsu, K.; Kawall, D.; Kawashima, M.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kim, B. I.; Kim, D. H.; Kim, D. J.; Kim, E.; Kim, E. J.; Kim, S. H.; Kim, Y. J.; Kinney, E.; Kiriluk, K.; Kiss, Á.; Kistenev, E.; Klein-Boesing, C.; Kochenda, L.; Komkov, B.; Konno, M.; Koster, J.; Kotchetkov, D.; Kozlov, A.; Král, A.; Kravitz, A.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K.; Lee, K. B.; Lee, K. S.; Leitch, M. J.; Leite, M. A. L.; Leitner, E.; Lenzi, B.; Li, X.; Liebing, P.; Linden Levy, L. A.; Liška, T.; Litvinenko, A.; Liu, H.; Liu, M. X.; Love, B.; Luechtenborg, R.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Malakhov, A.; Malik, M. D.; Manko, V. I.; Mannel, E.; Mao, Y.; Masui, H.; Matathias, F.; McCumber, M.; McGaughey, P. L.; Means, N.; Meredith, B.; Miake, Y.; Mignerey, A. C.; Mikeš, P.; Miki, K.; Milov, A.; Mishra, M.; Mitchell, J. T.; Mohanty, A. K.; Morino, Y.; Morreale, A.; Morrison, D. P.; Moukhanova, T. V.; Murata, J.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, T.; Nakano, K.; Newby, J.; Nguyen, M.; Nouicer, R.; Nyanin, A. S.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Oka, M.; Okada, K.; Onuki, Y.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, J.; Park, S. K.; Park, W. J.; Pate, S. F.; Pei, H.; Peng, J.-C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Rak, J.; Rakotozafindrabe, A.; Ravinovich, I.; Read, K. F.; Reygers, K.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosen, C. A.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Ruži?ka, P.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakashita, K.; Samsonov, V.; Sano, S.; Sato, T.; Sawada, S.; Sedgwick, K.; Seele, J.; Seidl, R.; Semenov, A. Yu.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slune?ka, M.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Sparks, N. A.; Stankus, P. W.; Stenlund, E.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sziklai, J.; Takagui, E. M.; Taketani, A.; Tanabe, R.; Tanaka, Y.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tarján, P.; Themann, H.; Thomas, T. L.; Togawa, M.; Toia, A.; Tomášek, L.; Torii, H.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Vale, C.; Valle, H.; van Hecke, H. W.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Vinogradov, A. A.; Virius, M.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.

    2012-09-01

    The second Fourier component v2 of the azimuthal anisotropy with respect to the reaction plane is measured for direct photons at midrapidity and transverse momentum (pT) of 1-12GeV/c in Au+Au collisions at sNN=200GeV. Previous measurements of this quantity for hadrons with pT<6GeV/c indicate that the medium behaves like a nearly perfect fluid, while for pT>6GeV/c a reduced anisotropy is interpreted in terms of a path-length dependence for parton energy loss. In this measurement with the PHENIX detector at the Relativistic Heavy Ion Collider we find that for pT>4GeV/c the anisotropy for direct photons is consistent with zero, which is as expected if the dominant source of direct photons is initial hard scattering. However, in the pT<4GeV/c region dominated by thermal photons, we find a substantial direct-photon v2 comparable to that of hadrons, whereas model calculations for thermal photons in this kinematic region underpredict the observed v2.

  9. Observation of direct-photon collective flow in Au + Au collisions at ?s(NN)] = 200 GeV.

    PubMed

    Adare, A; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Bataineh, H; Alexander, J; Aoki, K; Aramaki, Y; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Barish, K N; Bassalleck, B; Basye, A T; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Belmont, R; Bennett, R; Berdnikov, A; Berdnikov, Y; Bickley, A A; Bok, J S; Boyle, K; Brooks, M L; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Camacho, C M; Campbell, S; Chen, C-H; Chi, C Y; Chiu, M; Choi, I J; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; Connors, M; Constantin, P; Csanád, M; Csörg?, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; David, G; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Dutta, D; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Fields, D E; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Garishvili, I; Glenn, A; Gong, H; Gonin, M; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse Perdekamp, M; Gunji, T; Gustafsson, H-Å; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Hanks, J; Hartouni, E P; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, T K; Hester, T; Hill, J C; Hohlmann, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Ide, J; Ikeda, Y; Imai, K; Inaba, M; Isenhower, D; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Ivanischev, D; Jacak, B V; Jia, J; Jin, J; Johnson, B M; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kametani, S; Kamihara, N; Kamin, J; Kang, J H; Kapustinsky, J; Karatsu, K; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Khanzadeev, A; Kijima, K M; Kim, B I; Kim, D H; Kim, D J; Kim, E; Kim, E J; Kim, S H; Kim, Y J; Kinney, E; Kiriluk, K; Kiss, A; Kistenev, E; Klein-Boesing, C; Kochenda, L; Komkov, B; Konno, M; Koster, J; Kotchetkov, D; Kozlov, A; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, J; Lee, K; Lee, K B; Lee, K S; Leitch, M J; Leite, M A L; Leitner, E; Lenzi, B; Li, X; Liebing, P; Linden Levy, L A; Liška, T; Litvinenko, A; Liu, H; Liu, M X; Love, B; Luechtenborg, R; Lynch, D; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Mannel, E; Mao, Y; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; Means, N; Meredith, B; Miake, Y; Mignerey, A C; Mikeš, P; Miki, K; Milov, A; Mishra, M; Mitchell, J T; Mohanty, A K; Morino, Y; Morreale, A; Morrison, D P; Moukhanova, T V; Murata, J; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, T; Nakano, K; Newby, J; Nguyen, M; Nouicer, R; Nyanin, A S; O'Brien, E; Oda, S X; Ogilvie, C A; Oka, M; Okada, K; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, I H; Park, J; Park, S K; Park, W J; Pate, S F; Pei, H; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pinkenburg, C; Pisani, R P; Proissl, M; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Rakotozafindrabe, A; Ravinovich, I; Read, K F; Reygers, K; Riabov, V; Riabov, Y; Richardson, E; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Ruži?ka, P; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakashita, K; Samsonov, V; Sano, S; Sato, T; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Semenov, A Yu; Seto, R; Sharma, D; Shein, I; Shibata, T-A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slune?ka, M; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Sparks, N A; Stankus, P W; Stenlund, E; Stoll, S P; Sugitate, T; Sukhanov, A; Sziklai, J; Takagui, E M; Taketani, A; Tanabe, R; Tanaka, Y; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tarján, P; Themann, H; Thomas, T L; Togawa, M; Toia, A; Tomášek, L; Torii, H; Towell, R S; Tserruya, I; Tsuchimoto, Y; Vale, C; Valle, H; van Hecke, H W; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Vinogradov, A A; Virius, M; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Wei, F; Wei, R; Wessels, J; White, S N; Winter, D; Wood, J P; Woody, C L; Wright, R M; Wysocki, M; Xie, W; Yamaguchi, Y L; Yamaura, K; Yang, R; Yanovich, A; Ying, J; Yokkaichi, S; You, Z; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zolin, L

    2012-09-21

    The second Fourier component v(2) of the azimuthal anisotropy with respect to the reaction plane is measured for direct photons at midrapidity and transverse momentum (p(T)) of 1-12 GeV/c in Au + Au collisions at ?s(NN)] = 200 GeV. Previous measurements of this quantity for hadrons with p(T) < 6 GeV/c indicate that the medium behaves like a nearly perfect fluid, while for p(T) > 6 GeV/c a reduced anisotropy is interpreted in terms of a path-length dependence for parton energy loss. In this measurement with the PHENIX detector at the Relativistic Heavy Ion Collider we find that for p(T) > 4 GeV/c the anisotropy for direct photons is consistent with zero, which is as expected if the dominant source of direct photons is initial hard scattering. However, in the p(T) < 4 GeV/c region dominated by thermal photons, we find a substantial direct-photon v(2) comparable to that of hadrons, whereas model calculations for thermal photons in this kinematic region underpredict the observed v(2). PMID:23005942

  10. Technology assessment: observer study directly compares screen/film to CR mammography

    NASA Astrophysics Data System (ADS)

    Fletcher-Heath, Lynn; Richards, Anne; Ryan-Kron, Susan

    2007-03-01

    A new study supports and expands upon a previous reporting that computed radiography (CR) mammography offers as good, or better, image quality than state-of-the-art screen/film mammography. The suitability of CR mammography is explored through qualitative and quantitative study components: feature comparison and cancer detection rates of each modality. Images were collected from 150 normal and 50 biopsy-confirmed subjects representing a range of breast and pathology types. Comparison views were collected without releasing compression, using automatic exposure control on Kodak MIN-R films, followed by CR. Digital images were displayed as both softcopy (S/C) and hardcopy (H/C) for the feature comparison, and S/C for the cancer detection task. The qualitative assessment used preference scores from five board-certified radiologists obtained while viewing 100 screen/film-CR pairs from the cancer subjects for S/C and H/C CR output. Fifteen general image-quality features were rated, and up to 12 additional features were rated for each pair, based on the pathology present. Results demonstrate that CR is equivalent or preferred to conventional mammography for overall image quality (89% S/C, 95% H/C), image contrast (95% S/C, 98% H/C), sharpness (86% S/C, 93% H/C), and noise (94% S/C, 91% H/C). The quantitative objective was satisfied by asking 10 board-certified radiologists to provide a BI-RADS TM score and probability of malignancy per breast for each modality of the 200 cases. At least 28 days passed between observations of the same case. Average sensitivity and specificity was 0.89 and 0.82 for CR and 0.91 and 0.82 for screen/film, respectively.

  11. Direct Observations of Magnetic Anomalies on the Lunar Surface under Varying Solar Wind Conditions

    NASA Astrophysics Data System (ADS)

    Vorburger, A.; Wurz, P.; Barabash, S.; Wieser, M.; Futaana, Y.; Holmström, M.; Bhardwaj, A.; Dhanya, M. B.; Sridharan, R.; Asamura, K.

    2012-04-01

    In contrast to Earth, the Moon does not have a global dipolar magnetic field. Since the first lunar landing with Apollo 11, we know, though, that localised magnetic fields exist on the lunar surface. Measurements conducted by the Lunar Prospector magnetometer and electron reflectometer suggested that these localised magnetic fields are able to deflect the impinging solar wind in favourable cases (Lin et al., Science 1998). Magnetohydrodynamic simulations support the implication that mini-magnetospheres are formed above the locations of strong localised magnetic fields and can hold off the impinging solar wind (Harnett and Winglee, JGR 2002). Analysis of magnetic field data from Lunar Prospector of the Reiner Gamma anomaly region showed that the distortion of the magnetic field of this anomaly strongly depends on the impinging solar wind parameters, which was interpreted that the size and shape of the mini-magnetosphere changed with the solar wind parametes (Kurata et al., GRL 2005). Wieser et al., GRL 2010 showed that SARA, the Sub-KeV Atom Analyzer on board Chandrayaan-1, is able to detect an ENA image of the mini-magnetosphere in the measured energetic neutral atom flux. Here we analysed all orbits where CENA, the Chandrayaan-1 Energetic Neutral Analyzer, recorded data when a magnetic anomaly was in CENA's field-of-view. Our goal was to determine if 1) a signature of the magnetic anomaly is always visible in the ENA signal and if 2) there is a correlation between the solar wind dynamic pressure, the solar wind magnetic field, the local magnetic field strength and the reduction in the reflected ENA flux. Our results show that for the simplest case, i.e., the Gerasimovich anomaly, there is indeed a clear correlation between the shielding efficiency, the magnetic field strength and the solar wind dynamic pressure. For the other observed magnetic anomalies, for which the magnetic fields are not only weaker but also spatially more variable than that of the Gerasimovich anomaly, only in about half of the cases such a correlation was found. We therefore conclude that the magnetic anomaly interaction is in general quite complex and that data with higher spatial resolution and more detailed modelling is required to understand this process better.

  12. Direct Observation of a Defect-Mediated Viscoelastic Transition in a Hydrogel of Lipid Membranes and Polymer Lipids

    NASA Astrophysics Data System (ADS)

    Keller, S. L.; Warriner, H. E.; Safinya, C. R.; Zasadzinski, J. A.

    1997-06-01

    We present the first direct imaging of a new hydrogel of lipid membranes containing polymer lipids. Freeze-fracture electron microscopy shows unambiguously that the hydrogel's surprisingly large viscoelasticity is explained by a novel defect topology of interconnections between defects. The defects are spherulites with high membrane curvatures which are either isotropic or cylinderlike. A lower concentration of dislocation-type defects was also observed. The interconnections between the defects distinguish the hydrogel from simple ``onion'' phases of multilamellar vesicles with a smaller viscoelasticity.

  13. Direct Observation of the Bandwidth Control Mott Transition in the NiS2-xSex Multiband System

    NASA Astrophysics Data System (ADS)

    Xu, H. C.; Zhang, Y.; Xu, M.; Peng, R.; Shen, X. P.; Strocov, V. N.; Shi, M.; Kobayashi, M.; Schmitt, T.; Xie*, B. P.; Feng*, D. L.

    2015-03-01

    The bulk electronic structure of NiS2-xSex has been studied across the bandwidth-control Mott transition (BCMT) using soft x-ray angle-resolved photoemission spectroscopy. We show that Se doping does not alter the Fermi surface volume. When approaching the insulating phase with decreasing Se concentration, we observed that the Fermi velocity continuously decreases. Meanwhile, the weight of the coherent quasiparticle, which sits on a large incoherent spectrum, continuously decreases and is transferred to higher binding energies, until it suddenly disappears across the Mott transition. In the insulating phase, there is still finite spectral weight at the Fermi energy, but it is incoherent and dispersionless due to strong correlations. Our results provide a direct observation of the distinct characters of BCMT in a multiband non-half-filled system.

  14. HIGH-PRESSURE PHYSICS. Direct observation of an abrupt insulator-to-metal transition in dense liquid deuterium.

    PubMed

    Knudson, M D; Desjarlais, M P; Becker, A; Lemke, R W; Cochrane, K R; Savage, M E; Bliss, D E; Mattsson, T R; Redmer, R

    2015-06-26

    Eighty years ago, it was proposed that solid hydrogen would become metallic at sufficiently high density. Despite numerous investigations, this transition has not yet been experimentally observed. More recently, there has been much interest in the analog of this predicted metallic transition in the dense liquid, due to its relevance to planetary science. Here, we show direct observation of an abrupt insulator-to-metal transition in dense liquid deuterium. Experimental determination of the location of this transition provides a much-needed benchmark for theory and may constrain the region of hydrogen-helium immiscibility and the boundary-layer pressure in standard models of the internal structure of gas-giant planets. PMID:26113719

  15. Direct observation of crystal defects in an organic molecular crystals of copper hexachlorophthalocyanine by STEM-EELS

    PubMed Central

    Haruta, Mitsutaka; Kurata, Hiroki

    2012-01-01

    The structural analysis of crystal defects in organic thin films provides fundamental insights into their electronic properties for applications such as field effect transistors. Observation of crystal defects in organic thin films has previously been performed at rather low resolution by conventional transmission electron microscopy based on phase-contrast imaging. Herein, we apply for the first time annular dark-field imaging to the direct observation of grain boundaries in copper hexachlorophthalocyanine thin films at the atomic resolution level by using an aberration-corrected scanning transmission electron microscope combined with electron energy-loss spectroscopy. By using a low-dose technique and an optimized detection angle, we were able to visualize the contrast of light element (C and N) together with the heavier elements (Cl and Cu) within the molecular column. We were also able to identify unexpected molecular orientations in the grain boundaries along the {110} crystallographic planes giving rise to stacking faults. PMID:22355764

  16. Direct observation of the amphoteric behavior of Ge in InP modified by P co-implantation

    SciTech Connect

    Yu, K.M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Ridgway, M.C. [Department of Electronic Materials Engineering, Australian National University, Canberra, ACT 0200 (Australia)] [Department of Electronic Materials Engineering, Australian National University, Canberra, ACT 0200 (Australia)

    1997-08-01

    We have investigated the preferred substitution of Ge in InP by altering the local stoichiometry of the InP substrate. By co-implanting P with Ge to create a group V-rich environment, we directly observed an enhancement of the Ge substituting the In sublattice. A corresponding increase in the n-type conductivity by as much as three times was also observed in the Ge and P co-implanted sample. However, due to the altered local stoichiometry, the Ge solubility in InP was reduced by a factor of 2. The residual crystalline damage in the P co-implanted InP after annealing was also decreased due to the compensation of the nonstoichiometry related damage by the excess P in the middle of the implanted region. {copyright} {ital 1997 American Institute of Physics.}

  17. Direct Observation of the Bandwidth Control Mott Transition in the NiS2-xSex Multiband System

    NASA Astrophysics Data System (ADS)

    Xu, H. C.; Zhang, Y.; Xu, M.; Peng, R.; Shen, X. P.; Strocov, V. N.; Shi, M.; Kobayashi, M.; Schmitt, T.; Xie, B. P.; Feng, D. L.

    2014-02-01

    The bulk electronic structure of NiS2-xSex has been studied across the bandwidth-control Mott transition (BCMT) using soft x-ray angle-resolved photoemission spectroscopy. We show that Se doping does not alter the Fermi surface volume. When approaching the insulating phase with decreasing Se concentration, we observed that the Fermi velocity continuously decreases. Meanwhile, the weight of the coherent quasiparticle, which sits on a large incoherent spectrum, continuously decreases and is transferred to higher binding energies, until it suddenly disappears across the Mott transition. In the insulating phase, there is still finite spectral weight at the Fermi energy, but it is incoherent and dispersionless due to strong correlations. Our results provide a direct observation of the distinct characters of BCMT in a multiband non-half-filled system.

  18. Direct Observation and Control of Ultrafast Photoinduced Twisted Intramolecular Charge Transfer (TICT) in Triphenyl-Methane Dyes

    PubMed Central

    Li, Guifeng; Magana, Donny; Dyer, R. Brian

    2012-01-01

    Femtosecond time-resolved infrared spectroscopy was employed to study intramolecular charge transfer in triphenylmethane dyes, including malachite green (MG), malachite green carbinol base (MGCB), and leucomalachite green (LMG). A local excited state (LE) and a twisted intramolecular charge-transfer (TICT) state have been observed directly in MG. Furthermore, solvent-controlled TICT measurements in a series of linear alcohols indicate that the transition time (4–11 ps) from LE to TICT is strongly dependent on alcohol viscosity, which is due to rotational hindrance of dimethylaniline in high-viscosity solvents. For LMG, no TICT is observed due to steric hindrance caused by the sp3-hybridized central carbon atom. However, for MGCB, TICT is rescued by the addition of the electron-donating hydroxyl group to the bridge. These results for MG and its analogues provide new insight regarding the dynamics and mechanism of twisted intramolecular charge transfer (TICT) in triphenylmethane dyes. PMID:23009668

  19. Direct, intraoperative observation of ?0.1 Hz hemodynamic oscillations in awake human cortex: Implications for fMRI

    PubMed Central

    Rayshubskiy, Aleksandr; Wojtasiewicz, Teresa J.; Mikell, Charles B.; Bouchard, Matthew B.; Timerman, Dmitriy; Youngerman, Brett E.; McGovern, Robert A.; Otten, Marc L.; Canoll, Peter D.; McKhann, Guy M.; Hillman, Elizabeth M.C.

    2014-01-01

    An almost sinusoidal, large amplitude ?0.1 Hz oscillation in cortical hemodynamics has been repeatedly observed in species ranging from mice to humans. However, the occurrence of ‘slow sinusoidal hemodynamic oscillations’ (SSHOs) in human functional magnetic resonance imaging (fMRI) studies is rarely noted or considered. As a result, little investigation into the cause of SSHOs has been undertaken, and their potential to confound fMRI analysis, as well as their possible value as a functional biomarker has been largely overlooked. Here, we report direct observation of large-amplitude, sinusoidal ?0.1 Hz hemodynamic oscillations in the cortex of an awake human undergoing surgical resection of a brain tumor. Intraoperative multispectral optical intrinsic signal imaging (MS-OISI) revealed that SSHOs were spatially localized to distinct regions of the cortex, exhibited wave-like propagation, and involved oscillations in the diameter of specific pial arterioles, confirming that the effect was not the result of systemic blood pressure oscillations. fMRI data collected from the same subject 4 days prior to surgery demonstrates that ?0.1 Hz oscillations in the BOLD signal can be detected around the same region. Intraoperative optical imaging data from a patient undergoing epilepsy surgery, in whom sinusoidal oscillations were not observed, is shown for comparison. This direct observation of the ‘0.1 Hz wave’ in the awake human brain, using both intraoperative imaging and pre-operative fMRI, confirms that SSHOs occur in the human brain, and can be detected by fMRI. We discuss the possible physiological basis of this oscillation and its potential link to brain pathologies, highlighting its relevance to resting-state fMRI and its potential as a novel target for functional diagnosis and delineation of neurological disease. PMID:24185013

  20. Direct observation of R-loop formation by single RNA-guided Cas9 and Cascade effector complexes.

    PubMed

    Szczelkun, Mark D; Tikhomirova, Maria S; Sinkunas, Tomas; Gasiunas, Giedrius; Karvelis, Tautvydas; Pschera, Patrizia; Siksnys, Virginijus; Seidel, Ralf

    2014-07-01

    Clustered, regularly interspaced, short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems protect bacteria and archaea from infection by viruses and plasmids. Central to this defense is a ribonucleoprotein complex that produces RNA-guided cleavage of foreign nucleic acids. In DNA-targeting CRISPR-Cas systems, the RNA component of the complex encodes target recognition by forming a site-specific hybrid (R-loop) with its complement (protospacer) on an invading DNA while displacing the noncomplementary strand. Subsequently, the R-loop structure triggers DNA degradation. Although these reactions have been reconstituted, the exact mechanism of R-loop formation has not been fully resolved. Here, we use single-molecule DNA supercoiling to directly observe and quantify the dynamics of torque-dependent R-loop formation and dissociation for both Cascade- and Cas9-based CRISPR-Cas systems. We find that the protospacer adjacent motif (PAM) affects primarily the R-loop association rates, whereas protospacer elements distal to the PAM affect primarily R-loop stability. Furthermore, Cascade has higher torque stability than Cas9 by using a conformational locking step. Our data provide direct evidence for directional R-loop formation, starting from PAM recognition and expanding toward the distal protospacer end. Moreover, we introduce DNA supercoiling as a quantitative tool to explore the sequence requirements and promiscuities of orthogonal CRISPR-Cas systems in rapidly emerging gene-targeting applications. PMID:24912165

  1. Monte Carlo simulations derived from direct observations of individual bacteria inform macroscopic migration models at granular porous media interfaces.

    PubMed

    Kusy, Kevin; Ford, Roseanne M

    2007-09-15

    Motile bacteria accumulated at the interface between an aqueous solution and a polymer gel suspension. The gel suspension was produced using Gelrite and contained 50-500 microm semisolid gel particulates in aqueous buffer. Smooth-swimming (HCB437) and wild-type (HCB1) Escherchia coli displayed normal swimming behaviors in the aqueous buffer but exhibited no translational motion when obstructed by the semisolid particulates of the gel suspension. Translational motion immediately resumed after the bacteria reoriented in a direction away from the particle surfaces. These observations were incorporated into Monte Carlo simulations that linked individual swimming properties to macroscopic bacterial distributions. The simulations suggested that the apparent surface area of the porous media influenced the degree of bacteria/surface interactions and thatthe mechanism of surface association could concentrate bacterial populations based upon the physical constraints of the porous media system. Population distributions from the Monte Carlo simulations matched a 1-D transport model that characterized the bacteria/surface interactions as an adsorption-like process even though direct observations suggested no physical attachment was occurring. Consequently, the 1-D transport model provided a semiquantitative approach to approximate bacterial migrations within porous media systems. Results suggest that the self-propulsive nature of bacteria can produce nondiffusive migration patterns within high-surface area environments. PMID:17948786

  2. Illinois Withholding Allowance Worksheet Step 1: Figure your basic personal allowances (including allowances for dependents)

    E-print Network

    Bordenstein, Seth

    Illinois Withholding Allowance Worksheet Step 1: Figure your basic personal allowances (including to which you are entitled. 3 _______________ 4 If you want to have additional Illinois Income Tax withheld additional Illinois Income Tax withheld from your pay, you may reduce the number of additional allowances

  3. The energy balance over land and oceans: An assessment based on direct observations and CMIP5 climate models

    NASA Astrophysics Data System (ADS)

    Wild, Martin; Folini, Doris; Hakuba, Maria; Schär, Christoph; Seneviratne, Sonia; Kato, Seiji; Rutan, David; Ammann, Christof; Wood, Eric; König-Langlo, Gert

    2015-04-01

    The energy budgets over land and oceans are still afflicted with considerable uncertainties, despite their key importance for terrestrial and maritime climates. We evaluate these budgets as represented in 43 CMIP5 climate models with direct observations from both surface and space and identify substantial biases, particularly in the surface fluxes of downward solar and thermal radiation. These flux biases in the various models are then linearly related to their respective land and ocean means to infer best estimates for present day downward solar and thermal radiation over land and oceans. Over land, where most direct observations are available to constrain the surface fluxes, we obtain 184 and 306 Wm-2 for solar and thermal downward radiation, respectively. Over oceans, with weaker observational constraints, corresponding estimates are around 185 and 356 Wm-2. Considering additionally surface albedo and emissivity, we infer a surface absorbed solar and net thermal radiation of 136 and -66 Wm-2 over land, and 170 and -53 Wm-2 over oceans, respectively. The surface net radiation is thus estimated at 70 Wm-2 over land and 117 Wm-2 over oceans, which may impose additional constraints on the poorly known sensible/latent heat flux magnitudes, estimated here near 32/38 Wm-2 over land, and 16/100 Wm-2 over oceans. Estimated uncertainties are on the order of 10 and 5 Wm-2 for most surface and TOA fluxes, respectively. By combining these surface budgets with satellite-determined TOA budgets we quantify the atmospheric energy budgets as residuals (including ocean to land transports), and revisit the global mean energy balance. This study has recently been published online in Climate Dynamics.

  4. By performing sound scattering measurements with a detector array consisting of 62 elements in a flow between two counter-rotating disks we obtain the energy and vorticity power spectra directly in both spatial and temporal domains. Fast accumulated statistics and large signal-to-noise ratio allow to get high quality data rather effectively and to test scaling laws in details

    Microsoft Academic Search

    Shahar Seifer; Victor Steinberg

    One of the challenging experimental tasks in studies of turbulent flows is developing new tools to measure spec- tral characteristics of velocity and vorticity fields in a spa- tial domain. Such measurements will allow direct com- parison of experimental data with a theory without ex- ploiting the Taylor hypothesis particularly in those cases when its use is rather questionable. Currently,

  5. Je pense donc je fais: transcranial direct current stimulation modulates brain oscillations associated with motor imagery and movement observation

    PubMed Central

    Lapenta, Olivia M.; Minati, Ludovico; Fregni, Felipe; Boggio, Paulo S.

    2013-01-01

    Motor system neural networks are activated during movement imagery, observation and execution, with a neural signature characterized by suppression of the Mu rhythm. In order to investigate the origin of this neurophysiological marker, we tested whether transcranial direct current stimulation (tDCS) modifies Mu rhythm oscillations during tasks involving observation and imagery of biological and non-biological movements. We applied tDCS (anodal, cathodal, and sham) in 21 male participants (mean age 23.8 ± 3.06), over the left M1 with a current of 2 mA for 20 min. Following this, we recorded the EEG at C3, C4, and Cz and surrounding C3 and C4 electrodes. Analyses of C3 and C4 showed significant effects for biological vs. non-biological movement (p = 0.005), and differential hemisphere effects according to the type of stimulation (p = 0.04) and type of movement (p = 0.02). Analyses of surrounding electrodes revealed significant interaction effects considering type of stimulation and imagery or observation of biological or non-biological movement (p = 0.03). The main findings of this study were (1) Mu desynchronization during biological movement of the hand region in the contralateral hemisphere after sham tDCS; (2) polarity-dependent modulation effects of tDCS on the Mu rhythm, i.e., anodal tDCS led to Mu synchronization while cathodal tDCS led to Mu desynchronization during movement observation and imagery (3) specific focal and opposite inter-hemispheric effects, i.e., contrary effects for the surrounding electrodes during imagery condition and also for inter-hemispheric electrodes (C3 vs. C4). These findings provide insights into the cortical oscillations during movement observation and imagery. Furthermore, it shows that tDCS can be highly focal when guided by a behavioral task. PMID:23761755

  6. Direct observation of adsorption geometry for the van der Waals adsorption of a single ?-conjugated hydrocarbon molecule on Au(111)

    NASA Astrophysics Data System (ADS)

    Kim, Ju-Hyung; Jung, Jaehoon; Tahara, Kazukuni; Tobe, Yoshito; Kim, Yousoo; Kawai, Maki

    2014-02-01

    Weak van der Waals adsorption of ?-conjugated hydrocarbon molecules onto the gold surface, Au(111), is one of the essential processes in constructing organic-metal interfaces in organic electronics. Here we provide a first direct observation of adsorption geometry of a single ?-conjugated hydrocarbon molecule on Au(111) using an atomically resolved scanning tunneling microscopy study combined with van der Waals density functional methodology. For the purpose, we utilized a highly symmetric ?-conjugated hydrocarbon molecule, dehydrobenzo[12]annulene (DBA), which has a definite three-fold symmetry, the same as the Au(111) surface. Interestingly, our observations on an atomically resolved scale clearly indicate that the DBA molecule has only one adsorption configuration on Au(111) in spite of the weak van der Waals adsorption system. Based on the precisely determined adsorption geometry of DBA/Au(111), our calculation results imply that even a very small contribution of the interfacial orbital interaction at the organic-metal interface can play a decisive role in constraining the adsorption geometry even in the van der Waals adsorption system of a ?-conjugated hydrocarbon molecule on the noblest Au(111) surface. Our observations provide not only deeper insight into the weak adsorption process, but also new perspectives to organic electronics using ?-conjugated hydrocarbon molecules on the Au surface.

  7. Observation of early shell-dopant mix in OMEGA direct-drive implosions and comparisons with radiation-hydrodynamic simulations

    SciTech Connect

    Baumgaertel, J. A.; Bradley, P. A.; Hsu, S. C.; Cobble, J. A.; Hakel, P.; Tregillis, I. L.; Krasheninnikova, N. S.; Murphy, T. J.; Schmitt, M. J.; Shah, R. C.; Obrey, K. D.; Batha, S. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Johns, H.; Joshi, T.; Mayes, D.; Mancini, R. C.; Nagayama, T. [Physics Department, University of Nevada, Reno, Nevada 89557 (United States)

    2014-05-15

    Temporally, spatially, and spectrally resolved x-ray image data from direct-drive implosions on OMEGA were interpreted with the aid of radiation-hydrodynamic simulations. Neither clean calculations nor those using a turbulent mix model can explain fully the observed migration of shell-dopant material (titanium) into the core. Shell-dopant migration was observed via time-dependent, spatially integrated spectra, and spatially and spectrally resolved x-ray images of capsule implosions and resultant dopant emissions. The titanium emission was centrally peaked in narrowband x-ray images. In post-processed clean simulations, the peak titanium emission forms in a ring in self-emission images as the capsule implodes. Post-processed simulations with mix reproduce trends in time-dependent, spatially integrated spectra, as well having centrally peaked Ti emission in synthetic multiple monochromatic imager. However, mix simulations still do not transport Ti to the core as is observed in the experiment. This suggests that phenomena in addition to the turbulent mix must be responsible for the transport of Ti. Simple diffusion estimates are unable to explain the early Ti mix into the core. Mechanisms suggested for further study are capsule surface roughness, illumination non-uniformity, and shock entrainment.

  8. An assessment of Saharan dust loading and the corresponding cloud-free longwave direct radiative effect from geostationary satellite observations

    NASA Astrophysics Data System (ADS)

    Brindley, Helen E.; Russell, Jacqueline E.

    2009-12-01

    Previously, a method was developed to quantify Saharan dust optical thickness and simultaneously diagnose the cloud-free longwave dust direct radiative effect (LWDRE) over a single surface site using observations from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) and Geostationary Earth Radiation Budget (GERB) instrument both flying on the Meteosat Second Generation series of satellites. In this paper the overall utility of the approach is investigated using a more comprehensive suite of observations, and the inherent uncertainties associated with the method are assessed. On the basis of these findings, the approach has been updated to account for the effects of varying dust layer altitude. Comparisons with colocated observations from the Aerosol Robotic Network (AERONET) and Multiangle Imaging Spectroradiometer (MISR) using the modified approach indicate that the visible optical thickness at 0.55 ?m, ?055, can be obtained with an RMS uncertainty of ˜0.3 over North Africa and Arabia during sunlit hours, while monthly maps of optical depth derived over this region through spring and summer of 2006 show similar variability to that identified in the long-term climatology provided by the Total Ozone Mapping Spectrometer (TOMS) Aerosol Index. The regional mean instantaneous cloud-free LWDRE and associated LW radiative efficiency estimated from GERB over the same period are relatively constant with season, ranging from 9 to 11 W m-2 and 16-20 W m-2?055-1, respectively.

  9. Direct observation of adsorption geometry for the van der Waals adsorption of a single ?-conjugated hydrocarbon molecule on Au(111)

    SciTech Connect

    Kim, Ju-Hyung [Department of Advanced Materials Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan) [Department of Advanced Materials Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan); Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Jung, Jaehoon; Kim, Yousoo, E-mail: tobe@chem.es.osaka-u.ac.jp, E-mail: ykim@riken.jp, E-mail: maki@k.u-tokyo.ac.jp [Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)] [Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Tahara, Kazukuni; Tobe, Yoshito, E-mail: tobe@chem.es.osaka-u.ac.jp, E-mail: ykim@riken.jp, E-mail: maki@k.u-tokyo.ac.jp [Division of Frontier Materials Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan)] [Division of Frontier Materials Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Kawai, Maki, E-mail: tobe@chem.es.osaka-u.ac.jp, E-mail: ykim@riken.jp, E-mail: maki@k.u-tokyo.ac.jp [Department of Advanced Materials Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan)] [Department of Advanced Materials Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan)

    2014-02-21

    Weak van der Waals adsorption of ?-conjugated hydrocarbon molecules onto the gold surface, Au(111), is one of the essential processes in constructing organic-metal interfaces in organic electronics. Here we provide a first direct observation of adsorption geometry of a single ?-conjugated hydrocarbon molecule on Au(111) using an atomically resolved scanning tunneling microscopy study combined with van der Waals density functional methodology. For the purpose, we utilized a highly symmetric ?-conjugated hydrocarbon molecule, dehydrobenzo[12]annulene (DBA), which has a definite three-fold symmetry, the same as the Au(111) surface. Interestingly, our observations on an atomically resolved scale clearly indicate that the DBA molecule has only one adsorption configuration on Au(111) in spite of the weak van der Waals adsorption system. Based on the precisely determined adsorption geometry of DBA/Au(111), our calculation results imply that even a very small contribution of the interfacial orbital interaction at the organic-metal interface can play a decisive role in constraining the adsorption geometry even in the van der Waals adsorption system of a ?-conjugated hydrocarbon molecule on the noblest Au(111) surface. Our observations provide not only deeper insight into the weak adsorption process, but also new perspectives to organic electronics using ?-conjugated hydrocarbon molecules on the Au surface.

  10. Direct observation of spin-valley-layer locking in centrosymmetric bulk WSe2 by spin- and angle-resolved photoemission

    NASA Astrophysics Data System (ADS)

    King, Phil

    2015-03-01

    Methods to generate spin-polarized electronic states in non-magnetic solids are strongly desired to enable all-electrical manipulation of electron spins for new quantum devices. This is generally accepted to require breaking global structural inversion symmetry. In contrast, I will report our observation from spin- and angle-resolved photoemission spectroscopy of spin-polarized bulk states in the centrosymmetric transition-metal dichalcogenide 2H-WSe2. Mediated by a lack of inversion symmetry in constituent Se-W-Se monolayers of the bulk crystal where the electronic states are localized, we show how enormous spin splittings up to ~ 0 . 5 eV result, with a spin texture that is strongly modulated in both real and momentum space. Through this, our study provides direct experimental evidence for a putative locking of the spin with the layer and valley pseudospins in transition-metal dichalcogenides, of key importance for using these compounds in proposed valleytronic devices.

  11. Direct Observation of Localized Spin Antiferromagnetic Transition in PdCrO2 by Angle-Resolved Photoemission Spectroscopy

    PubMed Central

    Noh, Han-Jin; Jeong, Jinwon; Chang, Bin; Jeong, Dahee; Moon, Hyun Sook; Cho, En-Jin; Ok, Jong Mok; Kim, Jun Sung; Kim, Kyoo; Min, B. I.; Lee, Han-Koo; Kim, Jae-Young; Park, Byeong-Gyu; Kim, Hyeong-Do; Lee, Seongsu

    2014-01-01

    We report the first case of the successful measurements of a localized spin antiferromagnetic transition in delafossite-type PdCrO2 by angle-resolved photoemission spectroscopy (ARPES). This demonstrates how to circumvent the shortcomings of ARPES for investigation of magnetism involved with localized spins in limited size of two-dimensional crystals or multi-layer thin films that neutron scattering can hardly study due to lack of bulk compared to surface. Also, our observations give direct evidence for the spin ordering pattern of Cr3+ ions in PdCrO2 suggested by neutron diffraction and quantum oscillation measurements, and provide a strong constraint that has to be satisfied by a microscopic mechanism for the unconventional anomalous Hall effect recently reported in this system. PMID:24419488

  12. Direct observation of Young’s double-slit interferences in vibrationally resolved photoionization of diatomic molecules

    PubMed Central

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

    2011-01-01

    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.

  13. MGS nighttime observations of bi-directional electron conics over the moderate crustal magnetic sources on Mars

    NASA Astrophysics Data System (ADS)

    Ulusen, D.; Brain, D. A.; Mitchell, D.

    2009-12-01

    Conical distributions similar to bi-directional electron conics located near the auroral regions at Earth have been previously reported in the MGS MAG/ER data at Mars [Brain et al., 2007]. These bi-directional flux distributions are almost always symmetric about pitch angles of 90 degrees, with peaks at pitch angles from 30-70 and 110-150 degrees. About 300,000 of these events are detected over the nighttime hemisphere at 400 km altitude using electron angular distributions at 115 eV, but similar signatures are also detectable at energies from a few tens to hundreds of eV. Statistical analysis of the observations shows that these conics frequently occur over moderate horizontal crustal fields (~15 nT). The energy spectrum of the conics exhibit substantial decrease in all energy levels in relation to the spectra in the neighboring regions that don’t have conics. Typically these events are surrounded by either trapped or extended trapped radiation which implies that these conical distributions may be due to trapping of neighboring downward electrons on inner closed field lines. The absence of electrons at pitch angles around 90 degrees may be due to the fact that the only source of electrons for inner closed field lines is electrons scattered near the lower atmosphere. Or, similar to observations at Earth, diffusion in the pitch angles of trapped particles due to wave-particle interactions or time-varying electric fields may also be responsible for the loss of electrons around 90 degree pitch angles, which is also one of the main loss mechanisms of magnetically confined plasma at Earth. In this study we will report the characteristics of these events in detail and discuss their possible generation mechanisms.

  14. Direct observation of nanoscale Peltier and Joule effects at metal-insulator domain walls in vanadium dioxide nanobeams.

    PubMed

    Favaloro, Tela; Suh, Joonki; Vermeersch, Bjorn; Liu, Kai; Gu, Yijia; Chen, Long-Qing; Wang, Kevin X; Wu, Junqiao; Shakouri, Ali

    2014-05-14

    The metal to insulator transition (MIT) of strongly correlated materials is subject to strong lattice coupling, which brings about the unique one-dimensional alignment of metal-insulator (M-I) domains along nanowires or nanobeams. Many studies have investigated the effects of stress on the MIT and hence the phase boundary, but few have directly examined the temperature profile across the metal-insulating interface. Here, we use thermoreflectance microscopy to create two-dimensional temperature maps of single-crystalline VO2 nanobeams under external bias in the phase coexisting regime. We directly observe highly localized alternating Peltier heating and cooling as well as Joule heating concentrated at the M-I domain boundaries, indicating the significance of the domain walls and band offsets. Utilizing the thermoreflectance technique, we are able to elucidate strain accumulation along the nanobeam and distinguish between two insulating phases of VO2 through detection of the opposite polarity of their respective thermoreflectance coefficients. Microelasticity theory was employed to predict favorable domain wall configurations, confirming the monoclinic phase identification. PMID:24735496

  15. The interstellar medium in the direction of the Crab Nebula - Reconciling soft X-ray and radio observations

    NASA Technical Reports Server (NTRS)

    Ride, S. K.; Walker, A. B. C., Jr.

    1977-01-01

    The total soft X-ray photoabsorption cross section of the interstellar medium (ISM) in the direction of the Crab Nebula is computed on the basis of a two-phase model of the ISM. This cross section is used to reanalyze Copernicus data on the X-ray spectrum of the Crab between 0.7 and 1.5 keV. The total hydrogen column density along the line of sight to that nebula is found to be approximately 2.6 by 10 to the 21st power H atoms/sq cm. This result is evaluated in light of the two-phase model of the ISM, and the predictions based on the X-ray data are compared with results of radio and UV observations. A discrepancy between the radio and X-ray measurements of the hydrogen column density is resolved by noting that 21-cm absorption measurements sample only the neutral hydrogen in clouds while X-ray measurements are sensitive to all forms of hydrogen in both cloud and intercloud regions. It is suggested that roughly 50% of the hydrogen in the direction of the Crab Nebula is in clouds and that 85% of this hydrogen is neutral and atomic.

  16. Direct aerosol radiative forcing based on combined A-Train observations and comparisons to IPCC-2007 results

    NASA Astrophysics Data System (ADS)

    Redemann, J.; Shinozuka, Y.; Vaughan, M.; Russell, P. B.; Kacenelenbogen, M. S.; Livingston, J. M.; Torres, O.; Remer, L. A.

    2012-12-01

    We describe a technique for combining CALIOP aerosol backscatter, MODIS spectral AOD (aerosol optical depth), and OMI AAOD (absorption aerosol optical depth) measurements for the purpose of estimating full spectral sets of aerosol radiative properties, and ultimately for calculating the 3-D distribution of direct aerosol radiative forcing. As preparatory work, we carried out sensitivity studies, tested our methodology using suborbital observations, and investigated the consistency between various combinations of satellite input data sets. These studies were carried out largely to investigate the propagation of uncertainties in the multi-sensor input data into the aerosol radiative property estimates. We present results using one year of collocated CALIOP V3, MODIS and OMI data collected in 2007 and show comparisons of the aerosol radiative property estimates to collocated AERONET retrievals. An apparent bias in the input aerosol absorption optical depth and a related bias in the input aerosol single scattering albedo (SSA) are removed after application of the multi-sensor aerosol retrieval. We surmise that the removal of the SSA bias from the input data is a consequence of requiring the multi-sensor retrievals to be consistent with all input data and that the multi-sensor retrievals may be better constrained than retrievals from individual A-Train sensors. Initial calculations of seasonal clear-sky aerosol radiative forcing based on our multi-sensor aerosol retrievals compare well with over-ocean and top of the atmosphere IPCC-2007 model-based results, and with more recent assessments in the "Climate Change Science Program Report: Atmospheric Aerosol Properties and Climate Impacts" (hereafter referred to as CCSP-2009). This is noteworthy, since the observationally based estimates in CCSP-2009 did not compare well with the model-based estimates. Our multi-sensor based forcing calculations compare well with observationally based CCSP-2009 estimates at the surface, indicating that differences in column aerosol absorption properties between our assessment and the CCSP-2009 observationally based estimates need to be investigated. We emphasize that our forcing estimates are purely observational, without use of aerosol transport model assumptions. As such, our results should be well suited for comparisons to initiatives such as AeroCom (Aerosol Comparisons between Observations and Models), that ultimately aim to understand the differences in the 3-D distribution of aerosol radiative properties and effects in global aerosol models.

  17. Multiple-view spectrally resolved x-ray imaging observations of polar-direct-drive implosions on OMEGA

    NASA Astrophysics Data System (ADS)

    Mancini, R. C.; Johns, H. M.; Joshi, T.; Mayes, D.; Nagayama, T.; Hsu, S. C.; Baumgaertel, J. A.; Cobble, J.; Krasheninnikova, N. S.; Bradley, P. A.; Hakel, P.; Murphy, T. J.; Schmitt, M. J.; Shah, R. C.; Tregillis, I. L.; Wysocki, F. J.

    2014-12-01

    We present spatially, temporally, and spectrally resolved narrow- and broad-band x-ray images of polar-direct-drive (PDD) implosions on OMEGA. These self-emission images were obtained during the deceleration phase and bang time using several multiple monochromatic x-ray imaging instruments fielded along two or three quasi-orthogonal lines-of-sight, including equatorial and polar views. The instruments recorded images based on K-shell lines from a titanium tracer located in the shell as well as continuum emission. These observations constitute the first such data obtained for PDD implosions. The image data show features attributed to laser imprinting and zero-order hydrodynamics. Equatorial-view images show a "double bun" structure that is consistent with synthetic images obtained from post-processing 2D and 3D radiation-hydrodynamic simulations of the experiment. Polar-view images show a pentagonal, petal pattern that correlates with the PDD laser illumination used on OMEGA, thus revealing a 3D aspect of PDD OMEGA implosions not previously observed. Differences are noted with respect to a PDD experiment performed at National Ignition Facility.

  18. Self-determination and compliance in directly observed therapy of tuberculosis treatment in the Kingdom of Lesotho.

    PubMed

    George, Laura J

    2008-01-01

    Public health officials have created directly observed therapy, short course (DOTS) to treat tuberculosis (TB) and to guarantee that drugs are taken in the right combination and for the appropriate duration. The World Health Organization (WHO) uses supervisors (nurses, nursing assistants, and community health workers [CHWs], as well as community members and relatives), to watch the patient take his or her TB medication. This article explores the observation component of DOTS, and how DOTS supervisors enhance patients' ability to comply with TB treatment by providing enablers, education, and supportive relationships. It also explores how supervisors can achieve the balance between patients' right to self-determination and a community's need for social accountability. Social work can contribute to the efficacy of TB treatment by helping public health officials understand the importance of balancing patients' rights and society's needs in determining the allocation of program resources. The results of this study are based on data gathered from 71 researcher-administered questionnaires and 25 semi-structured interviews in seven of the Kingdom of Lesotho's 19 health service areas. It was found that by providing enablers, education, and supportive relationships, DOTS supervisors ameliorate some of the logistical problems that prevent compliance. Noncompliance for patients is often an institutional/managerial problem that denies patients access to services and resources and should not be blamed on them. PMID:18589565

  19. Observation of Anisotropy in the Galactic Cosmic-Ray Arrival Directions at 400 TeV with IceCube

    NASA Astrophysics Data System (ADS)

    Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Allen, M. M.; Altmann, D.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; BenZvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Brown, A. M.; Buitink, S.; Caballero-Mora, K. S.; Carson, M.; Chirkin, D.; Christy, B.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; Cruz Silva, A. H.; D'Agostino, M. V.; Danninger, M.; Daughhetee, J.; Davis, J. C.; De Clercq, C.; Degner, T.; Demirörs, L.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; DeYoung, T.; Díaz-Vélez, J. C.; Dierckxsens, M.; Dreyer, J.; Dumm, J. P.; Dunkman, M.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feintzeig, J.; Feusels, T.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Góra, D.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gurtner, M.; Ha, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Heinen, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Hoffmann, B.; Homeier, A.; Hoshina, K.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobi, E.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Kroll, G.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Laihem, K.; Landsman, H.; Larson, M. J.; Lauer, R.; Lünemann, J.; Madsen, J.; Marotta, A.; Maruyama, R.; Mase, K.; Matis, H. S.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Miarecki, S.; Middell, E.; Milke, N.; Miller, J.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Panknin, S.; Paul, L.; Pérez de los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, C. C.; Price, P. B.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Richman, M.; Rodrigues, J. P.; Rothmaier, F.; Rott, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Schmidt, T.; Schönwald, A.; Schukraft, A.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Strahler, E. A.; Ström, R.; Stüer, M.; Sullivan, G. W.; Swillens, Q.; Taavola, H.; Taboada, I.; Tamburro, A.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Tosi, D.; van Eijndhoven, N.; Vandenbroucke, J.; Van Overloop, A.; van Santen, J.; Vehring, M.; Voge, M.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, C.; Xu, D. L.; Xu, X. W.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.; Zoll, M.; IceCube Collaboration

    2012-02-01

    In this paper we report the first observation in the Southern hemisphere of an energy dependence in the Galactic cosmic-ray anisotropy up to a few hundred TeV. This measurement was performed using cosmic-ray-induced muons recorded by the partially deployed IceCube observatory between 2009 May and 2010 May. The data include a total of 33 × 109 muon events with a median angular resolution of ~3°. A sky map of the relative intensity in arrival direction over the Southern celestial sky is presented for cosmic-ray median energies of 20 and 400 TeV. The same large-scale anisotropy observed at median energies around 20 TeV is not present at 400 TeV. Instead, the high-energy sky map shows a different anisotropy structure including a deficit with a post-trial significance of -6.3?. This anisotropy reveals a new feature of the Galactic cosmic-ray distribution, which must be incorporated into theories of the origin and propagation of cosmic rays.

  20. Direct Torque Control with Full Order Stator Flux Observer for Dual-Three Phase Induction Motor Drives

    NASA Astrophysics Data System (ADS)

    Farina, Francesco; Bojoi, Radu; Tenconi, Alberto; Profumo, Francesco

    A Direct Torque Control (DTC) strategy for dual-three phase induction motor drives is discussed in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees with isolated neutral points. The proposed control strategy is based on Proportional Integral (PI) regulators implemented in the stator flux synchronous reference frame. To improve the flux estimation, an Adaptive Stator Flux Observer (ASFO) has been used. Doing so, besides a better flux estimation in contrast to open-loop flux estimators, it is possible to use the observed currents to compensate the inverter non-linear behavior (such as dead-time effects), improving the drive performance at low speed. This is particularly important for low voltage/high current applications, as the drive considered in this paper. The advantages of the discussed control strategy are: constant inverter switching frequency, good transient and steady-state performance and less distorted machine currents in contrast to DTC schemes with variable switching frequency. Experimental results are presented for a 10kW dual three-phase induction motor drive prototype.

  1. Direct observation of t-butyl alcohol frozen and sublimated samples using low-vacuum scanning electron microscopy.

    PubMed

    Hashizume, H; Itoh, S; Tanaka, K; Ushiki, T

    1998-05-01

    Frozen biological specimens in t-butyl alcohol were examined under a low-vacuum environment in a "wet SEM" or "variable pressure SEM (scanning electron microscope)" equipped with a cooling stage and highly sensitive backscattered detector of the YAG type. After fixation with glutaraldehyde and osmium tetroxide, rat tissue blocks (tracheae and kidneys), and cultured human carcinoma cells were dehydrated with a graded series of t-butyl alcohol. The specimens were directly frozen on the cooling stage at -10 degrees C, evacuated to 20 Pa in the specimen chamber, and observed by detecting backscattered electrons at accelerating voltages of 5-6 kV. The images became clearer 20 min after the vacuum reached 20 Pa and revealed had good quality by 30 min, probably because t-butyl alcohol was sublimated during the time. The cilia of tracheal ciliated cells, end-feet of the podocytes of the renal glomerulus, and processes of cultured cells were clearly observed without any serious preparation artifacts. Since the low-vacuum SEM of t-butyl alcohol frozen samples is both simple and provides high imaging quality, it is expected to be useful in a variety of biological fields such as the rapid pathological diagnosis. PMID:9650884

  2. Observation of Anisotropy in the Galactic Cosmic Ray Arrival Directions at 400 TEV With IceCube

    NASA Technical Reports Server (NTRS)

    Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Allen, M. M.; Altmann, D.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo, Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K. H.; Benabderrahmane, M. L.; Benzvi, S.; Berdermann, J.; Stamatikos, M.

    2011-01-01

    In this paper we report the first observation in the Southern hemisphere of an energy dependence in the Galactic cosmic ray anisotropy up to a few hundred TeV. This measurement was performed using cosmic ray induced muons recorded by the partially deployed IceCube observatory between May 2009 and May 2010. The data include a total of 33x l0(epx 9) muon events with a median angular resolution of approx 3 degrees. A sky map of the relative intensity in arrival direction over the Southern celestial sky is presented for cosmic ray median energies of 20 and 400 Te V. The same large-scale anisotropy observed at median energies around 20 TeV is not present at 400 TeV. Instead, the high energy skymap shows a different anisotropy structure including a deficit with a post-trial significance of -6.30 sigma. This anisotropy reveals a new feature of the Galactic cosmic ray distribution, which must be incorporated into theories of the origin and propagation of cosmic rays.

  3. Observation of an Anisotropy in the Galactic Cosmic Ray Arrival Direction at 400 TeV with IceCube

    NASA Technical Reports Server (NTRS)

    Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Allen, M. M.; Altmann, D.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K. H.; Benabderrahmane, M. L.; BenZvi, S.; Berdermann, J.; Stamatikos, M.

    2012-01-01

    In this paper we report the first observation in the Southern hemisphere of an energy dependence in the Galactic cosmic ray anisotropy up to a few hundred TeV. This measurement was performed using cosmic ray induced muons recorded by the partially deployed IceCube observatory between May 2009 and May 2010. The data include a total of 33 x 10(exp 9) muon events with a median angular resolution of approx. 3 degrees. A sky map of the relative intensity in arrival direction over the Southern celestial sky is presented for cosmic ray median energies of 20 and 400 TeV. The same large-scale anisotropy observed at median energies around 20 TeV is not present at 400 TeV. Instead, the high energy skymap shows a different anisotropy structure including a deficit with a post-trial significance of -6.3 sigma. This anisotropy reveals a new feature of the Galactic cosmic ray distribution, which must be incorporated into theories of the origin and propagation of cosmic rays.

  4. Direct observation of single stationary-phase bacteria reveals a surprisingly long period of constant protein production activity.

    PubMed

    Gefen, Orit; Fridman, Ofer; Ronin, Irine; Balaban, Nathalie Q

    2014-01-01

    Exponentially growing bacteria are rarely found in the wild, as microorganisms tend to spend most of their lifetime at stationary phase. Despite this general prevalence of stationary-phase bacteria, they are as yet poorly characterized. Our goal was to quantitatively study this phase by direct observation of single bacteria as they enter into stationary phase and by monitoring their activity over several days during growth arrest. For this purpose, we devised an experimental procedure for starving single Escherichia coli bacteria in microfluidic devices and measured their activity by monitoring the production rate of fluorescent proteins. When amino acids were the sole carbon source, the production rate decreased by an order of magnitude upon entry into stationary phase. We found that, even while growth-arrested, bacteria continued to produce proteins at a surprisingly constant rate over several days. Our identification of this newly observed period of constant activity in nongrowing cells, designated as constant activity stationary phase, makes possible the conduction of assays that require constant protein expression over time, and are therefore difficult to perform under exponential growth conditions. Moreover, we show that exogenous protein expression bears no fitness cost on the regrowth of the population when starvation ends. Further characterization of constant activity stationary phase-a phase where nongrowing bacteria can be quantitatively studied over several days in a reproducible manner-should contribute to a better understanding of this ubiquitous but overlooked physiological state of bacteria in nature. PMID:24344288

  5. Direct Observations of Tether-cutting Reconnection during a Major Solar Event from 2014 February 24 to 25

    NASA Astrophysics Data System (ADS)

    Chen, Huadong; Zhang, Jun; Cheng, Xin; Ma, Suli; Yang, Shuhong; Li, Ting

    2014-12-01

    Using multi-wavelength data from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, we investigated two successive solar flares, a C5.1 confined flare and an X4.9 ejective flare with a halo coronal mass ejection, in NOAA active region 11990 from 2014 February 24 to 25. Before the confined flare onset, EUV brightening beneath the filament was detected. As the flare began, a twisted helical flux rope (FR) wrapping around the filament moved upward and then stopped, and in the meantime an obvious X-ray source below it was observed. Prior to the ejective X4.9 flare, some pre-existing loop structures in the active region interacted with each other, which produced a brightening region beneath the filament. Meanwhile, a small flaring loop appeared below the interaction region and some new helical lines connecting the far ends of the loop structures were gradually formed and continually added into the former twisted FR. Then, due to the resulting imbalance between the magnetic pressure and tension, the new FR, together with the filament, erupted outward. Our observations coincide well with a tether-cutting model, suggesting that the two flares probably have the same triggering mechanism, i.e., tether-cutting reconnection. To our knowledge, this is the first direct observation of tether-cutting reconnection occurring between pre-existing loops in an active region. In the ejective flare case, the erupting filament exhibited an ?-like kinked structure and underwent an exponential rise after a slow-rise phase, indicating that the kink instability might be also responsible for the eruption initiation.

  6. Direct Spectroscopic Observation of Fe(III)-Phenolate Complex Formed From the Reaction of Benzene With Peroxide Species on Fe/ZSM-5 At Room Temperature

    E-print Network

    Li, Weixue

    as a precursor for phenol resins, fibers, dyestuffs, and medicine. The direct oxidation of benzene to phenolDirect Spectroscopic Observation of Fe(III)-Phenolate Complex Formed From the Reaction of Benzene reflectance and Raman spectroscopies. For the first time, the intermediate Fe(III)-phenolate complex

  7. Utility allowed returns and market extremes

    SciTech Connect

    Murry, D.A.; Nan, G.D.; Harrington, B.M.

    1993-03-01

    In recent years interest rates have fluctuated from exceptionally high levels in the early 1980s to their current levels, the lowest in two decades. Observers and analysts generally have assumed that allowed returns by regulatory commissions follow the movement of interest rates; indeed some analysts use a risk premium method to estimate the cost of common equity, assuming a constant and linear relationship between interest rates and the cost of common equity. That suggests we could expect a relatively stable relationship between interest rates and allowed returns, as well. However, a simple comparison of allowed returns and interest rates shows that this is not the case in recent years. The relationship between market interest rates and the returns allowed by commissions varies and is obviously a great deal more complicated. Empirically, there appears to be only a narrow range where market interest rates significantly affect the allowed returns on common stock set by state commissions, at least for electric and combination utilities. If rates are at historically low levels, allowed returns based largely on market rates will hasten subsequent rate filings, and commissions appear to look beyond the low rate levels. Conversely, it appears that regulators do not let historically high market rates determine allowed returns either. At either high or low interest levels, caution seems to be the policy.

  8. Direct observation of cosmic strings via their strong gravitational lensing effect - II. Results from the HST/ACS image archive

    NASA Astrophysics Data System (ADS)

    Morganson, Eric; Marshall, Phil; Treu, Tommaso; Schrabback, Tim; Blandford, Roger D.

    2010-08-01

    We have searched 4.5deg2 of archival Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) images for cosmic strings, identifying close pairs of similar, faint galaxies and selecting groups whose alignment is consistent with gravitational lensing by a long, straight string. We find no evidence for cosmic strings in five large-area HST treasury surveys (covering a total of 2.22deg2) or in any of 346 multifilter guest observer images (1.18deg2). Assuming that simulations accurately predict the number of cosmic strings in the Universe, this non-detection allows us to place upper limits on the dimensionless Universal cosmic string tension of G?/c2 < 2.3 × 10-6 and cosmic string density of ?s < 2.1 × 10-5 at the 95per cent confidence level (marginalizing over the other parameter in each case). We find four dubious cosmic string candidates in 318 single-filter guest observer images (1.08deg2), which we are unable to conclusively eliminate with existing data. The confirmation of any of these candidates as cosmic strings would imply G?/c2 ~ 10-6 and ?s ~ 10-5. However, we estimate that there is at least a 92per cent chance that these string candidates are random alignments of galaxies. If we assume that these candidates are indeed false detections, our final limits on G?/c2 and ?s fall to 6.5 × 10-7 and 7.3 × 10-6, respectively. Due to the extensive sky coverage of the HST/ACS image archive, the above limits are universal. They are quite sensitive to the number of fields being searched and could be further reduced by more than a factor of 2 using forthcoming HST data.

  9. Fast searching on compressed text allowing errors

    Microsoft Academic Search

    Edleno Silva de Moura; Gonzalo Navarro; Nivio Ziviani; Ricardo A. Baeza-Yates

    1998-01-01

    We present a fast compression and decom- pression scheme for natural language texts that allows efficient and flexible string matching by searching the compressed text directly. The compression scheme uses a word-based Huffman encoding and the coding alpha- bet is byte-oriented rather than bit-oriented. We com- press typical English texts to about 30% of their original size, against 40% and

  10. Direct observation of electron emission from the grain boundaries of chemical vapour deposition diamond films by tunneling atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Chatterjee, Vijay; Harniman, Robert; May, Paul W.; Barhai, P. K.

    2014-04-01

    The emission of electrons from diamond in vacuum occurs readily as a result of the negative electron affinity of the hydrogenated surface due to features with nanoscale dimensions, which can concentrate electric fields high enough to induce electron emission from them. Electrons can be emitted as a result of an applied electric field (field emission) with possible uses in displays or cold-cathode devices. Alternatively, electrons can be emitted simply by heating the diamond in vacuum to temperatures as low as 350 °C (thermionic emission), and this may find applications in solar energy generation or energy harvesting devices. Electron emission studies usually use doped polycrystalline diamond films deposited onto Si or metallic substrates by chemical vapor deposition, and these films have a rough, faceted morphology on the micron or nanometer scale. Electron emission is often improved by patterning the diamond surface into sharp points or needles, the idea being that the field lines concentrate at the points lowering the barrier for electron emission. However, there is little direct evidence that electrons are emitted from these sharp tips. The few reports in the literature that have studied the emission sites suggested that emission came from the grain boundaries and not the protruding regions. We now present direct observation of the emission sites over a large area of polycrystalline diamond using tunneling atomic force microscopy. We confirm that the emission current comes mostly from the grain boundaries, which is consistent with a model for emission in which the non-diamond phase is the source of electrons with a threshold that is determined by the surrounding hydrogenated diamond surface.

  11. Prolonged Infectiousness of Tuberculosis Patients in a Directly Observed Therapy Short-Course Program with Standardized Therapy

    PubMed Central

    Fitzwater, Sean P.; Caviedes, Luz; Gilman, Robert H.; Coronel, Jorge; LaChira, Doris; Salazar, Cayo; Saravia, Juan Carlos; Reddy, Krishna; Friedland, Jon S.; Moore, David A. J.

    2015-01-01

    Background Effective tuberculosis control is compromised by a lack of clarity about the timeframe of viable Mycobacterium tuberculosis shedding after treatment initiation under programmatic conditions. This study quantifies time to conversion from smear and culture positivity to negativity in unselected tuberculosis patients receiving standardized therapy in a directly observed therapy short-course (DOTS) program. Methods Longitudinal cohort study following up 93 adults initiating tuberculosis therapy in Lima, Peru. Baseline culture and drug susceptibility tests (DSTs) were performed using the MBBacT, proportion, and microscopic observation drug susceptibility (MODS) methods. Smear microscopy and MODS liquid culture were performed at baseline and weekly for 4 weeks then every other week for 26 weeks. Results Median conversion time from culture positivity to culture negativity of 38.5 days was unaffected by baseline smear status. Patients with fully susceptible tuberculosis had a median time to culture conversion of 37 days; 10% remained culture positive at day 60. Delayed culture conversion was associated with multidrug resistance, regardless of DST method used; non–multidrug resistance as defined by the proportion method and MODS (but not MBBacT) was also associated with delay. Persistent day 60 smear positivity yielded positive and negative predictive values of 67% and 92%, respectively, for detecting multidrug resistance. Conclusions Smear and culture conversion in treated tuberculosis patients takes longer than is conventionally believed, even with fully susceptible disease, and must be accounted for in tuberculosis treatment and prevention programs. Persistent day 60 smear positivity is a poor predictor of multidrug resistance. The industrialized-world convention of universal baseline DST for tuberculosis patients should become the standard of care in multidrug resistance–affected resource-limited settings. PMID:20624064

  12. Outcome of a grocery voucher incentive scheme for low-income tuberculosis patients on directly observed therapy in Singapore

    PubMed Central

    Chua, Angeline Poh-Gek; Lim, Leo Kang-Yang; Ng, Huiyi; Chee, Cynthia Bin-Eng; Wang, Yee Tang

    2015-01-01

    INTRODUCTION The ‘DOT & Shop’ scheme is sponsored by SATA CommHealth, a local non-governmental organisation. It was launched in July 2009, in collaboration with Singapore’s Tuberculosis Control Unit (TBCU). Under this scheme, grocery vouchers are disbursed to low-income patients with tuberculosis (TB) at each clinic visit if they have been adherent to directly observed therapy (DOT). This study aimed to determine the effect of this incentive scheme on treatment completion rates and to report the characteristics of patients who were non-adherent to the scheme. METHODS This descriptive study used data from the TBCU medical social worker database and the National TB Registry. RESULTS From July 2009 to December 2012, a total of 883 TB patients were enrolled in the scheme. The overall treatment completion rates of the patients before (July 2006–June 2009) and after (July 2009–December 2012) the implementation of the scheme improved from 85.3% to 87.2% (p = 0.02). Patients under this scheme had a higher treatment completion rate (90.0%) than those not under this scheme (86.4%) (p < 0.01). It was found that the non-adherent patients were more likely to be of Malay ethnicity, younger and unemployed. CONCLUSION We demonstrate the salutary effect of a non-governmental organisation-funded grocery voucher incentive scheme for low-income TB patients on DOT in Singapore. PMID:25788246

  13. Lyman Alpha Line Spectra of the First Galaxies: Dependence on Observed Direction to the Underlying CDM Filament

    E-print Network

    Masakazu A. R. Kobayashi; Hideyuki Kamaya; Atsunori Yonehara

    2005-09-17

    The first galaxies in the Universe are built up where cold dark matter (CDM) forms large scale filamentary structure. Although the galaxies are expected to emit numerous Lya photons, they are surrounded by plentiful neutral hydrogen with a typical optical depth for Lya of ~10^5 (HI halos) before the era of cosmological reionization. The HI halo almost follows the cosmological Hubble expansion with some anisotropic corrections around the galaxy because of the gravitational attraction by the underlying CDM filament. In this paper, we investigate the detectability of the Lya emissions from the first galaxies, examining their dependence on viewing angles. Solving the Lya line transfer problem in an anisotropically expanding HI halo, we show that the escape probability from the HI halo is the largest in direction along the filament axis. If the Lya source is observed with a narrow-band filter, the difference of apparent Lya line luminosities among viewing angles can be a factor of > 40 at an extreme case. Furthermore, we evaluate the predicted physical features of the Lya sources and flux magnification by gravitational lensing effect due to clusters of galaxies along the filament. We conclude that, by using the next generation space telescopes like the JWST, the Lya emissions from the first galaxies whose CDM filament axes almost face to us can be detected with the S/N of > 10.

  14. Ly? Line Spectra of the First Galaxies: Dependence on Observed Direction to the Underlying Cold Dark Matter Filament

    NASA Astrophysics Data System (ADS)

    Kobayashi, Masakazu A. R.; Kamaya, Hideyuki; Yonehara, Atsunori

    2006-01-01

    The first galaxies in the universe are built up where cold dark matter (CDM) forms large-scale filamentary structure. Although the galaxies are expected to emit numerous Ly? photons, they are surrounded by plentiful neutral hydrogen with a typical optical depth for Ly? of ~105 (H I halos) before the era of cosmological reionization. The H I halo almost follows the cosmological Hubble expansion with some anisotropic corrections around the galaxy because of gravitational attraction by the underlying CDM filament. In this paper, we investigate the detectability of the Ly? emissions from the first galaxies, examining their dependence on viewing angles. Solving the Ly? line transfer problem in an anisotropically expanding H I halo, we show that the escape probability from the H I halo is the largest in the direction along the filament axis. If the Ly? source is observed with a narrowband filter, the difference in apparent Ly? line luminosities among viewing angles can be a factor of >~40 for an extreme case. Furthermore, we evaluate the predicted physical features of the Ly? sources and flux magnification by the gravitational lensing effect due to clusters of galaxies along the filament. We conclude that by using next-generation space telescopes such as JWST, the Ly? emissions from the first galaxies whose CDM filament axes almost face us can be detected with S/N>~10.

  15. Detailed study of the direct numerical observation of the Kramers turnover in the LiNC?LiCN isomerization rate

    NASA Astrophysics Data System (ADS)

    Müller, P. L. García; Hernandez, Rigoberto; Benito, R. M.; Borondo, F.

    2012-11-01

    According to Kramers, rates of molecular process are expected to follow a rise and fall from low friction (at little to no interaction with the environment) to high friction (at typical liquid densities and above). This so-called Kramers turnover was recently observed and delineated in the case of the LiNC?LiCN isomerization reaction in the presence of an argon bath [P. García-Müller, R. Hernandez, R. M. Benito, and F. Borondo, Phys. Rev. Lett. 101, 178302 (2008)], 10.1103/PhysRevLett.101.178302. The rates were obtained using direct molecular dynamics of an all-atom representation and the Langevin dynamics of a projected representation. We now provide further evidence that the forward and backward rates are indeed exhibiting the turnover. The rates are also seen to agree remarkably well with the Pollak-Grabert-Hänggi rate formulas in regimes satisfying the theory underlying assumptions. At higher temperatures, when the theory is expected to fail, the solvated LiCN isomerization continues to exhibit activated dynamics following the turnover.

  16. THE FIRST GROUND LEVEL ENHANCEMENT EVENT OF SOLAR CYCLE 24: DIRECT OBSERVATION OF SHOCK FORMATION AND PARTICLE RELEASE HEIGHTS

    SciTech Connect

    Gopalswamy, N.; Xie, H.; Akiyama, S.; Yashiro, S.; Davila, J. M. [NASA Goddard Space Flight Center, Greenbelt, Maryland, MD (United States); Usoskin, I. G. [Sodankylae Geophysical Observatory (Oulu unit) and Department of Physics, University of Oulu, FI-90014 Oulu (Finland)

    2013-03-10

    We report on the 2012 May 17 ground level enhancement (GLE) event, which is the first of its kind in solar cycle 24. This is the first GLE event to be fully observed close to the surface by the Solar Terrestrial Relations Observatory (STEREO) mission. We determine the coronal mass ejection (CME) height at the start of the associated metric type II radio burst (i.e., shock formation height) as 1.38 Rs (from the Sun center). The CME height at the time of GLE particle release was directly measured from a STEREO image as 2.32 Rs, which agrees well with the estimation from CME kinematics. These heights are consistent with those obtained for cycle-23 GLEs using back-extrapolation. By contrasting the 2012 May 17 GLE with six other non-GLE eruptions from well-connected regions with similar or larger flare sizes and CME speeds, we find that the latitudinal distance from the ecliptic is rather large for the non-GLE events due to a combination of non-radial CME motion and unfavorable solar B0 angle, making the connectivity to Earth poorer. We also find that the coronal environment may play a role in deciding the shock strength.

  17. Observation of direct magneto-dielectric behaviour in Lu3Fe5O12-? above room-temperature.

    PubMed

    Manimuthu, P; Vidya, R; Ravindran, P; Fjellvåg, H; Venkateswaran, C

    2015-07-01

    The coupling of dielectric and magnetic order is highly nontrivial and seldom observed in rare-earth iron garnets. Careful investigations on polycrystalline Lu3Fe5O12-?, prepared by the solid state route, establish a direct correlation between the magnetic and dielectric order parameters. A dielectric anomaly at the magnetic ordering temperature supports this correlation. The dielectric permittivity at various magnetic fields is measured using an indigenously developed connector setup. Lu3Fe5O12-? exhibits a magneto-dielectric coupling of ?6% at room temperature, which is significant in the case of a single-phase magneto-dielectric material at low fields. Rietveld refinement of the X-ray diffraction pattern, bond valence sum method, Mössbauer spectroscopy, and X-ray photoelectron spectroscopy indicate two different oxidation states of Fe. Complete structural optimizations performed using the density functional theory establish a ferrimagnetic ground state and provide structural parameters in agreement with experimental values. Electronic structure analysis shows that Lu3Fe5O12 exhibits insulating behavior both in ferromagnetic and ferrimagnetic configurations. The capability of Lu3Fe5O12-? to exhibit room temperature magneto-dielectric response is a key factor in designing and fabricating various electronic devices and sensors. PMID:26080760

  18. Computing 3-D wavefields in mantle circulations models to test hypotheses on the origin of lower mantle heterogeneity under Africa directly against seismic observations

    NASA Astrophysics Data System (ADS)

    Schuberth, Bernhard; Zaroli, Christophe; Nolet, Guust

    2015-04-01

    Of particular interest for the tectonic evolution of the Atlantic region is the influence of lower mantle structure under Africa on flow in the upper mantle beneath the ocean basin. Along with its Pacific counterpart, the large African anomaly in the lowermost mantle with strongly reduced seismic velocities has received considerable attention in seismological and geodynamic studies. Several seismological observations are typically taken as an indication that these two anomalies are being caused by large-scale compositional variations and that they are piles of material with higher density than normal mantle rock. This would imply negative buoyancy in the lowermost mantle under Africa, which has important implications for the flow at shallower depth and inferences on the processes that led to the formation of the Atlantic Ocean basin. However, a large number of recent studies argue for a strong thermal gradient across the core-mantle boundary that might provide an alternative explanation for the lower mantle anomaly through the resulting large lateral temperature variations. Recently, we developed a new joint forward modeling approach to test such geodynamic hypotheses directly against the seismic observations: Seismic heterogeneity is predicted by converting the temperature field of a high-resolution 3-D mantle circulation model into seismic velocities using thermodynamic models of mantle mineralogy. 3-D global wave propagation in the synthetic elastic structures is then simulated using a spectral element method. Being based on forward modelling only, this approach allows us to generate synthetic wavefields and seismograms independently of seismic observations. The statistics of observed long-period body wave traveltime variations show a markedly different behaviour for P- and S-waves: the standard deviation of P-wave delay times stays almost constant with ray turning depth, while that of the S-wave delay times increases strongly throughout the mantle. In an earlier study, we showed that synthetic traveltime variations computed for an isochemical mantle circulation model with strong core heating can reproduce these different trends. This was taken as a strong indication that seismic heterogeneity in the lower mantle is likely dominated by thermal variations on large length-scales (i.e., relevant for long-period body waves). We will discuss the robustness of this earlier conclusion by exploring the uncertainties in the mineralogical models used to convert temperatures to seismic velocities. In particular, we investigate the influence of anelasticity on the standard deviation of our synthetic traveltime variations. Owing to the differences in seismic frequency content between laboratory measurements (MHz to GHz) and the Earth (mHz to Hz), the seismic velocities given in the mineralogical model need to be adjusted; that is, corrected for dispersion due to anelastic effects.

  19. Generalizability and Dependability of Behavior Assessment Methods to Estimate Academic Engagement: A Comparison of Systematic Direct Observation and Direct Behavior Rating

    ERIC Educational Resources Information Center

    Briesch, Amy M.; Chafouleas, Sandra M.; Riley-Tillman, T. Chris

    2010-01-01

    Although substantial attention has been directed toward building the psychometric evidence base for academic assessment methods (e.g., state mastery tests, curriculum-based measurement), similar examination of behavior assessment methods has been comparatively limited, particularly with regard to assessment purposes most desirable within…

  20. Star formation activity in spiral galaxy disks and the properties of radio halos: Observational evidence for a direct dependence

    NASA Technical Reports Server (NTRS)

    Dahlem, Michael; Lisenfeld, Ute; Golla, Gotz

    1995-01-01

    In this article we address observationally the questions: how does star formation (SF) in the disks of galaxies lead to the creation of radio halos, and what minimum energy input into the interstellar medium (ISM) is needed to facilitate this? For the investigation we use a sample of five edge-on galaxies exhibiting radio continuum emmission in their halos and enhanced SF spread over large parts of their disks. In a detailed study of the two galaxies in our sample for which we have the best data, NGC 891 and NGC 4631, we show that the radio halos cut off abruptly at galactocentric radii smaller than those of the underlying thin radio disks. Our most important result is that the halo cutoffs are spatially coincident with the radii where the SF activity in the underlying disks drops sharply. The difference in radius of the emission distributions tracing ongoing SF in the disks (IRAS 50 micrometers, H alpha) versus that of the nonthermal radio continuum thin disks (tracing the distribution of cosmic-ray (CR) electrons) is typically a few kpc. This difference in extent is caused by CR diffusion. We have measured the CR diffusion coefficients in the thin disks of both NGC 891 and NGC 4631. For radial diffusion of CR electrons within the galactic disks the values are D(sub r) = 1.1-2.5 x 10 (exp 29) sq cm/s (NGC 4631) and D(sub r) = 1.2 x 10(exp 29) sq cm/s (NGC 891). For motions in the z-direction in areas within the thin disks where no outflows occur, we derive a firm upper limit of D(sub z) less than or equal to 0.2 x 10(exp 28) sq cm/s for NGC 891. The value for NGC 4631 is D(sub z = 1.4 x 10 (exp 28) sq cm/s. The other three galaxies in our sample, NGC 3044, NGC 4666, and NGC 5775 show (at the sensitivity of our data) less extended, more filamentary radio halos. Isolates spurs or filaments of nonthermal radio continuum emission in their halos are traced only above the most actively star-forming regions in the disks. This, in conjuction with the results obtained for NGC 891 and NGC 4631, suggests a direct connection between the shapes and radial extents of radio halos of normal galaxies and the level and the spatial distribution of the current SF in their disks. The existence of filamentary structures implies that expansion and convection of CR-heated plasma plays an important role even at low z-distances above the plane. Based on radio data we derive the disk-averaged mean energy input rates into the ISM due to supernova explosions per unit surface area in nine galaxies, including the ones in our sample. We find a clear trend in the sense that the galaxies with the highest mean energy input rates in the underlying disks have the most extended and pervasisve radio halos. Below a certain threshohld, outflows are inhibited. As a lower limit for this threshhold we derive an energy input rate of approximately 10 (exp -4) erg/s sq cm. The fact that radio halo emission is found only above the most luminous giant H 2 regions in late-type 'normal' galaxies (of type Sbc or later) indicates that only these are capable of initiating disk-halo interactions by locally exceeding the threshold. The distribution of the local outflows determines the overall shapes of the CR halos and leads to the observed filamentary structures.

  1. The quality of sputum smear microscopy in public-private mix directly observed treatment laboratories in West Amhara region, Ethiopia.

    PubMed

    Manalebh, Almaw; Demissie, Meaza; Mekonnen, Daniel; Abera, Bayeh

    2015-01-01

    Ethiopia adopted Public-Private Mix Directly Observed Treatment Short Course Chemotherapy (PPM-DOTS) strategy for tuberculosis (TB) control program. Quality of sputum smear microscopy has paramount importance for tuberculosis control program in resource-poor countries like Ethiopia. A cross-sectional study was conducted to assess the quality of sputum smear microscopy in 37 Public-Private Mix laboratories in West Amhara, Ethiopia. The three external quality assessment methods (onsite evaluation, panel testing and blind rechecking) were employed. Onsite assessment revealed that 67.6% of PPM-DOTS laboratories were below the standard physical space (5 X 6) m2. The average monthly workload per laboratory technician was 19.5 (SD±2.9) slides with 12.8% positivity rate. The quality of Acid Fast Bacilli (AFB) staining reagents was sub-standard. The overall agreement for blind rechecking of 1,123 AFB slides was 99.4% (Kappa = 0.97). Reading of 370 AFB panel slides showed 3.5% false reading (Kappa = 0.92). Moreover, the consistency of reading scanty bacilli slides was lower (93%) compared to 1+, 2+ and 3+ bacilli. Based on blind rechecking and panel testing results, PPM-DOTS site laboratories showed good agreement with the reference laboratory. Physical space and qualities of AFB reagents would be areas of intervention to sustain the quality of sputum smear microscopy. Therefore, regular external quality assessment and provision of basic laboratory supplies for TB diagnosis would be the way forward to improve the quality of sputum smear microscopy services in PPM-DOTS laboratories. PMID:25849516

  2. Using direct observation, formal evaluation, and an interactive curriculum to improve the sign-out practices of internal medicine interns.

    PubMed

    Gakhar, Bhavna; Spencer, Abby L

    2010-07-01

    The safe transfer (handoff) of responsibility for patient care from one physician to another requires that health care facilities have rigorous sign-out systems and that physicians develop effective communication skills. In 2007 and 2008, to improve the spoken and written sign-out practices of the 25 interns at Allegheny General Hospital (Pittsburgh, Pennsylvania), the authors designed and administered Likert scale surveys about training in and satisfaction with current sign-out practices; directly observed and evaluated interns performing spoken sign-outs; assessed and graded interns' sign-out sheets; and compared sign-out sheets with patient records to evaluate their accuracy. On the basis of their findings, the authors developed a new curriculum with didactic and interactive components to target intern-level and system-level problems. The curriculum emphasized the importance of complete and accurate sign-outs, provided examples of good and poor sign-outs, and assigned interns to work in small groups to practice sign-out skills and receive feedback from peers and program leaders. Reevaluation of interns two months after curriculum implementation revealed not only better performance on each of the seven items evaluated for spoken sign-out but also substantial improvement in the completeness of sign-out sheets and the accuracy of reporting of identification data, code status, and medications data. The curriculum was well received by interns, and it helped them develop skills required by the Accreditation Council for Graduate Medical Education, including competencies in communication, practice-based learning, and systems-based practice. PMID:20375830

  3. Direct Numerical Simulation of Pore-Scale Flow in a Bead Pack: Comparison with Magnetic Resonance Imaging Observations

    SciTech Connect

    Yang, Xiaofan; Scheibe, Timothy D.; Richmond, Marshall C.; Perkins, William A.; Vogt, Sarah J.; Codd, Sarah L.; Seymour, Joseph D.; Mckinley, Matthew I.

    2013-04-01

    A significant body of current research is aimed at developing methods for numerical simulation of flow and transport in porous media that explicitly resolve complex pore and solid geometries, and at utilizing such models to study the relationships between fundamental pore-scale processes and macroscopic manifestations at larger (i.e., Darcy) scales. A number of different numerical methods for pore-scale simulation have been developed, and have been extensively tested and validated for simplified geometries. However, validation of pore-scale simulations of fluid velocity for complex, three-dimensional (3D) pore geometries that are representative of natural porous media is challenging due to our limited ability to measure pore-scale velocity in such systems. Recent advances in magnetic resonance imaging (MRI) offer the opportunity to measure not only the pore geometry, but also local fluid velocities under steady-state flow conditions in 3D and with high spatial resolution. In this paper, we present a 3D velocity field measured at sub-pore resolution (tens of micrometers) over a centimeter-scale 3D domain using MRI methods. We have utilized the measured pore geometry to perform 3D simulations of Navier-Stokes flow over the same domain using direct numerical simulation techniques. We present a comparison of the numerical simulation results with the measured velocity field. It is shown that the numerical results match the observed velocity patterns well overall except for a variance and small systematic scaling which can be attributed to the known experimental error in the MRI measurements. The comparisons presented here provide strong validation of the pore-scale simulation methods and new insights for interpretation of uncertainty in MRI measurements of pore-scale velocity. This study also provides a potential benchmark for future comparison of other pore-scale simulation methods.

  4. The Quality of Sputum Smear Microscopy in Public-Private Mix Directly Observed Treatment Laboratories in West Amhara Region, Ethiopia

    PubMed Central

    Manalebh, Almaw; Demissie, Meaza; Mekonnen, Daniel; Abera, Bayeh

    2015-01-01

    Ethiopia adopted Public-Private Mix Directly Observed Treatment Short Course Chemotherapy (PPM-DOTS) strategy for tuberculosis (TB) control program. Quality of sputum smear microscopy has paramount importance for tuberculosis control program in resource-poor countries like Ethiopia. A cross-sectional study was conducted to assess the quality of sputum smear microscopy in 37 Public-Private Mix laboratories in West Amhara, Ethiopia. The three external quality assessment methods (onsite evaluation, panel testing and blind rechecking) were employed. Onsite assessment revealed that 67.6% of PPM-DOTS laboratories were below the standard physical space (5 X 6) m2. The average monthly workload per laboratory technician was 19.5 (SD±2.9) slides with 12.8% positivity rate. The quality of Acid Fast Bacilli (AFB) staining reagents was sub-standard. The overall agreement for blind rechecking of 1,123 AFB slides was 99.4% (Kappa = 0.97). Reading of 370 AFB panel slides showed 3.5% false reading (Kappa = 0.92). Moreover, the consistency of reading scanty bacilli slides was lower (93%) compared to 1+, 2+ and 3+ bacilli. Based on blind rechecking and panel testing results, PPM-DOTS site laboratories showed good agreement with the reference laboratory. Physical space and qualities of AFB reagents would be areas of intervention to sustain the quality of sputum smear microscopy. Therefore, regular external quality assessment and provision of basic laboratory supplies for TB diagnosis would be the way forward to improve the quality of sputum smear microscopy services in PPM-DOTS laboratories. PMID:25849516

  5. Development and Testing of a Direct Observation Code Training Protocol for Elementary Aged Students with Attention Deficit/Hyperactivity Disorder

    ERIC Educational Resources Information Center

    Steiner, Naomi J.; Sidhu, Tahnee; Rene, Kirsten; Tomasetti, Kathryn; Frenette, Elizabeth; Brennan, Robert T.

    2013-01-01

    Observational measures can add objective data to both research and clinical evaluations of children's behavior in the classroom. However, they pose challenges for training and attaining high levels of interrater reliability between observers. The Behavioral Observation of Students in Schools (BOSS) is a commonly used school-based observation…

  6. An Observational Approach to Testing Bi-Directional Parent-Child Interactions as Influential to Child Eating and Weight

    ERIC Educational Resources Information Center

    Demir, Defne; Skouteris, Helen; Dell'Aquila, Daniela; Aksan, Nazan; McCabe, Marita P.; Ricciardelli, Lina A.; Milgrom, Jeannette; Baur, Louise A.

    2012-01-01

    Obesity among children has been on the rise globally for the past few decades. Previous research has centred mainly on self/parent-reported measures examining only uni-directional parental feeding styles and practices. Recent discussions in the literature have raised the importance of bi-directional parent-child interactions in influencing…

  7. The Self Reported Aggravating Activities of Chronic Non Specific Low Back Pain Patients Do Not Demonstrate a Consistent Directional Pattern: an observational study

    Microsoft Academic Search

    Benedict M Wand; Rebecca Hunter; Neil E OConnell; Louise Marston; James McAuley

    2009-01-01

    Question: Do the self-reported aggravating activities of chronic non-specific low back pain patients demonstrate a consistent directional pattern?\\u000aDesign: Cross-sectional observational study. Participants: 240 chronic non specific low back pain patients.\\u000aOutcome measure: We invited experienced clinicians to classify each of the three self-nominated aggravating activities from the Patient Specific Functional Scale by the direction of lumbar spine movement. Patients

  8. Detachment of Tertiary Dendrite Arms during Controlled Directional Solidification in Aluminum - 7 wt Percent Silicon Alloys: Observations from Ground-based and Microgravity Processed Samples

    NASA Technical Reports Server (NTRS)

    Grugel, Richard N.; Erdman, Robert; Van Hoose, James R.; Tewari, Surendra; Poirier, David

    2012-01-01

    Electron Back Scattered Diffraction results from cross-sections of directionally solidified aluminum 7wt% silicon alloys unexpectedly revealed tertiary dendrite arms that were detached and mis-oriented from their parent arm. More surprisingly, the same phenomenon was observed in a sample similarly processed in the quiescent microgravity environment aboard the International Space Station (ISS) in support of the joint US-European MICAST investigation. The work presented here includes a brief introduction to MICAST and the directional solidification facilities, and their capabilities, available aboard the ISS. Results from the ground-based and microgravity processed samples are compared and possible mechanisms for the observed tertiary arm detachment are suggested.

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

    Microsoft Academic Search

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

    2000-01-01

    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

  10. Using direct observations on multiple occasions to measure household food availability among low-income Mexicano residents in Texas colonias

    PubMed Central

    2010-01-01

    Background It has been recognized that the availability of foods in the home are important to nutritional health, and may influence the dietary behavior of children, adolescents, and adults. It is therefore important to understand food choices in the context of the household setting. Considering their importance, the measurement of household food resources becomes critical. Because most studies use a single point of data collection to determine the types of foods that are present in the home, which can miss the change in availability within a month and when resources are not available, the primary objective of this pilot study was to examine the feasibility and value of conducting weekly in-home assessments of household food resources over the course of one month among low-income Mexicano families in Texas colonias. Methods We conducted five in-home household food inventories over a thirty-day period in a small convenience sample; determined the frequency that food items were present in the participating households; and compared a one-time measurement with multiple measurements. After the development and pre-testing of the 252-item culturally and linguistically- appropriate household food inventory instrument that used direct observation to determine the presence and amount of food and beverage items in the home (refrigerator, freezer, pantry, elsewhere), two trained promotoras recruited a convenience sample of 6 households; administered a baseline questionnaire (personal info, shopping habits, and food security); conducted 5 in-home assessments (7-day interval) over a 30-day period; and documented grocery shopping and other food-related activities within the previous week of each in-home assessment. All data were collected in Spanish. Descriptive statistics were calculated for mean and frequency of sample characteristics, food-related activities, food security, and the presence of individual food items. Due to the small sample size of the pilot data, the Friedman Test and Kendall's W were used to assess the consistency of household food supplies across multiple observations. Results Complete data were collected from all 6 Mexicano women (33.2y ± 3.3; 6.5 ± 1.5 adults/children in household (HH); 5 HH received weekly income; and all were food insecure. All households purchased groceries within a week of at least four of the five assessments. The weekly presence and amounts of fresh and processed fruits and vegetables, dairy, meats, breads, cereals, beverages, and oils and fats varied. Further, the results revealed the inadequacy of a one-time measurement of household food resources, compared with multiple measures. The first household food inventory as a one-time measure would have mistakenly identified at least one-half of the participant households without fresh fruit, canned vegetables, dairy, protein foods, grains, chips, and sugar-sweetened beverages. Conclusions This study highlights the value of documenting weekly household food supplies, especially in households where income resources may be more volatile. Clearly, the data show that a single HFI may miss the changes in availability - presence and amount - that occur among low-income Mexicano households who face challenges that require frequent purchase of foods and beverages. Use of multiple household food inventories can inform the development and implementation of nutrition-related policies and culturally sensitive nutrition education programs. PMID:20670423

  11. Aerosol Optical Depth over Europe: Evaluation of the CALIOPE air quality modelling system with direct-sun AERONET observations

    NASA Astrophysics Data System (ADS)

    Basart, Sara; Pay, María. Teresa; Pérez, Carlos; Cuevas, Emilio; Jorba, Oriol; Piot, Matthias; María Baldasano, Jose

    2010-05-01

    In the frame of the CALIOPE project (Baldasano et al., 2008), the Barcelona Supercomputing Center (BSC-CNS) currently operates a high-resolution air quality forecasting system based on daily photochemical forecasts in Europe (12km x 12km resolution) with the WRF-ARW/HERMES/CMAQ modelling system (http://www.bsc.es/caliope) and desert dust forecasts over Southern Europe with BSC-DREAM8b (Pérez et al., 2006; http://www.bsc.es/projects/earthscience/DREAM). High resolution simulations and forecasts are possible through their implementation on MareNostrum supercomputer at BSC-CNS. As shown in previous air quality studies (e.g. Rodríguez et al., 2001; Jiménez-Guerrero et al., 2008), the contribution of desert dust on particulate matter levels in Southern Europe is remarkable due to its proximity to African desert dust sources. When considering only anthropogenic emissions (Baldasano et al., 2008) and the current knowledge about aerosol physics and chemistry, chemistry-transport model simulations underestimate the PM10 concentrations by 30-50%. As a first approach, the natural dust contribution from BSC-DREAM8b is on-line added to the anthropogenic aerosol output of CMAQ. The aim of the present work is the quantitative evaluation of the WRF-ARW/HERMES/ CMAQ/BSC-DREAM8b forecast system to simulate the Aerosol Optical Depth (AOD) over Europe. The performance of the modelled AOD has been quantitatively evaluated with discrete and categorical (skill scores) statistics by a comparison to direct-sun AERONET observations for 2004. The contribution of different types of aerosols will be analyzed by means of the O'Neill fine mode AOD products (O'Neill et al., 2001). A previous aerosol characterization of AERONET data was performed (Basart et al., 2009) in order to discriminate the different aerosol source contributions within the study region. The results indicate a remarkable improvement in the discrete and skill-scores evaluation (accuracy, critical success index and probability of detection) of AOD when using CMAQ+DREAM8b compared to CMAQ-alone simulations. An accurate analysis of the relative contributions of anthropogenic aerosols and desert dust to AOD over Europe and their seasonality will be also presented. References: Baldasano J.M, P. Jiménez-Guerrero, O. Jorba, C. Pérez, E. López, P. Güereca, F. Martin, M. García-Vivanco, I. Palomino, X. Querol, M. Pandolfi, M.J. Sanz and J.J. Diéguez: "CALIOPE: An operational air quality forecasting system for the Iberian Peninsula, Balearic Islands and Canary Islands- First annual evaluation and ongoing developments", Adv. Sci. and Res., 2: 89-98, 2008. Baldasano J.M., L. P. Güereca, E. López, S. Gassó, P. Jimenez-Guerrero. "Development of a high resolution (1 km x 1 km, 1 h) emission model for Spain: the High-Elective Resolution Modelling Emission System (HERMES)". Atmospheric Environment, 42: 7215-7233 doi: 10.1016/j.atmosenv.2008.07.026, 2008. Basart, S., Pérez, C., Cuevas, E., Baldasano, J. M. and Gobbi, G. P. "Aerosol characterization in Northern Africa, Northeastern Atlantic, Mediterranean Basin and Middle East from direct-sun AERONET observations", Atmos. Chem. Phys.., 9, 7707-7745, 2009. Jiménez-Guerrero, P., Pérez, C., Jorba, O. and Baldasano, J. M. "Contribution of Saharan dust in an integrated air quality system and its on-line assessment", Geophys. Res. Lett., 35(3), 2008. O'Neill, N. T., Dubovik, O., and Eck, T. F.: A modified Angstrom coefficient for the characterization of sub-micron aerosols, App. Opt., 40(14), 2368-2375, 2001. Pérez, C., Nickovic, S., Pejanovic, G., Baldasano, J. M. and Ozsoy, E. "Interactive dust-radiation modeling: A step to improve weather forecasts", Geophys. Res., 11(D16206),doi:10.1029/2005JD006717, 2006. Rodríguez, S., Querol, X., Alastuey, A., Kallos, G. and Kakaliagou, O. "Saharan dust contributions to PM10 and TSP levels in Southern and Eastern Spain", Atmos. Environ., 35, 2433-2447, 2001.

  12. A DIRECT OBSERVATION TECHNIQUE FOR EVALUATING SCLEROTIUM GERMINATION BY MACROPHOMINA PHASEOLINA AND EFFECTS OF BIOCONTROL MATERIALS ON SURVIVAL OF SCLEROTIA IN SOIL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Germination of sclerotia of Macrophomina phaseolina was quantified by direct microscopic observation following application of experimental treatments in vitro and incubation of sclerotia in soil. Survival in soil was evaluated at different moisture levels and with and without poultry litter amendme...

  13. Physical activity patterns of rural Senegalese adolescent girls during the dry and rainy seasons measured by movement registration and direct observation methods

    Microsoft Academic Search

    E Bénéfice; C Cames

    1999-01-01

    Objective: To study the physical activity patterns and daily estimates of energy expenditure (EE) of rural adolescent Senegalese girls.Design: Physical activity was monitored using a portable accelerometer during four consecutive days and within the same time, by direct observation during two consecutive days. Adolescent girls were followed during the dry season (June, n=40) and again during the rainy season (September,

  14. Direct small-angle-neutron-scattering observation of stretched chain conformation in nanocomposites: More insight on polymer contributions in mechanical reinforcement

    E-print Network

    Paris-Sud XI, Université de

    Direct small-angle-neutron-scattering observation of stretched chain conformation in nanocomposites on the elastic modulus. One increasingly recognized point is filler dispersion. It acts on geometrical reinforcement. Re- cent simulations yield a similar picture 13 . Getting the single chain form factor by small

  15. Observation directe de la croissance d'hydrosilicate de calcium sur des surfaces d'alité et de silice par microscopie à force atomique

    NASA Astrophysics Data System (ADS)

    Gauffinet, Sandrine; Finot, Éric; Lesniewska, Eric; Nonat, André

    1998-08-01

    Direct observation of the growth of calcium silicate hydrates, the tricalcium silicate hydration products, at the solid-solution interface were performed by atomic force microscopy. The covering of the surface of alite or silica by a three-dimensional oriented aggregation of nano particles of calcium silicate hydrate is always observed whatever the sample. All observations and quantifications made on calcium silicate growth at the submicronic level are in agreement with the data deduced from the study of the system evolution at the macroscopic level.

  16. Direct Observation of Hyperfine Quenching of the (2)3p0 Level in Helium-Like Nickel

    E-print Network

    Dunford, R. W.; Liu, C. J.; Last, J.; Berrahmansour, N.; Vondrasek, R.; Church, David A.; Curtis, L. J.

    1991-01-01

    We report a clear demonstration of the effect of hyperfine quenching of a forbidden transition by direct comparison of the lifetimes of the 2 3P0 level in the heliumlike isotopes Ni-61(26+) and Ni-58(26+). We find the quenched lifetime of the 2 3P0...

  17. Volcanic steam output directly measured in fumaroles: the observed variations at Vulcano Island, Italy, between 1983 and 1987

    Microsoft Academic Search

    F. Italiano; P M Nuccio

    1992-01-01

    The mass of steam emitted by the fumaroles of the crater of Vulcano (Aeolian Islands, Italy) was evaluated by using a direct measuring method. Measurements were effected with this method between 1983 and 1987 in nine field campaigns, the results of which are given in this paper. The steam flux measurements were performed by an instrument expressly designed for steam

  18. Modeling the response of the induced magnetosphere of Venus to changing IMF direction using MESSENGER and Venus Express observations

    Microsoft Academic Search

    Mehdi Benna; Mario H. Acuña; Brian J. Anderson; Stanislav Barabash; Scott A. Boardsen; George Gloeckler; Robert E. Gold; George C. Ho; Haje Korth; Stamatios M. Krimigis; Ralph L. McNutt; Jim M. Raines; Menelaos Sarantos; James A. Slavin; Sean C. Solomon; Tielong L. Zhang; Thomas H. Zurbuchen

    2009-01-01

    The second MESSENGER flyby of Venus on 5 June 2007 provided a new opportunity to study the response of the induced magnetosphere of the planet to changes in the direction of the interplanetary magnetic field (IMF). At the time of the MESSENGER flyby, the European Space Agency's Venus Express spacecraft was located outside the magnetosphere and provided a monitor of

  19. Dust devil speeds, directions of motion and general characteristics observed by the Mars Express High Resolution Stereo Camera

    Microsoft Academic Search

    Christina Stanzel; Martin Pätzold; David A. Williams; Patrick L. Whelley; Ronald Greeley; Gerhard Neukum

    2008-01-01

    A total of 205 dust devils were detected in 23 High Resolution Stereo Camera (HRSC) images taken between January 2004 and July 2006 with the ESA Mars Express orbiter, in which average dust devil heights were ?660 m and average diameters were ?230 m. For the first time, dust devil velocities were directly measured from orbit, and range from 1

  20. Direct Observation of Hyperfine Quenching of the (2)3p0 Level in Helium-Like Nickel 

    E-print Network

    Dunford, R. W.; Liu, C. J.; Last, J.; Berrahmansour, N.; Vondrasek, R.; Church, David A.; Curtis, L. J.

    1991-01-01

    We report a clear demonstration of the effect of hyperfine quenching of a forbidden transition by direct comparison of the lifetimes of the 2 3P0 level in the heliumlike isotopes Ni-61(26+) and Ni-58(26+). We find the ...

  1. Empirical Research on the Radical Subjective Solution of the Measurement Problem. Does Time get its Direction through Conscious Observation?

    NASA Astrophysics Data System (ADS)

    Bierman, Dick J.

    2006-10-01

    In a number of experimental studies we explored the so-called `radical subjective', and rather controversial, solution of the measurement problem. This solution posits that an interaction with a conscious entity is required to complete the measurement. Thus the collapse of the wave packet is assumed to be causally linked to a conscious observation. Under the assumption that the brain is sensitive for the difference between observing a quantum (superposition) state and a classical state this radical solution can be tested. A radioactive source was used to trigger beeps that first were delayed for 1 second and then were observed by a (final) observer from whom a continuous recording of brain activity was made. In about 50% of the events, another (pre) observer got feedback of this quantum event before the final observer. In those cases, presumably the pre-observer's observation resulted in collapse of the wave-packet while in the other half of the cases the final observer was `producing' the collapse. The brain signals of the final observer for the two types of events were compared. The ambiguous results of the studies will be discussed. If consciousness is the crucial ingredient for `collapse' to occur, then this might also give a new anthropocentric hypothesis with regard to the `arrow of time'. The projection postulate implies a irreversible process of reduction and hence can be seen as one of the few non time-symmetric processes in physics. If consciousness is required to have a collapse then it might follow that consciousness introduces time asymmetry into physics. New neuro-cognitive models of consciousness suggest that the neural correlate of conscious experience (rather than non conscious processing) is the occurrence of massive parallel recurrent (i.e. non linear) neural activation. Thus the collapse of the wave packet would become associated with a strong non-linear process. This fits, at least in a metaphorical sense, with the theoretical results where an introduction on a non linear term in the Schrödinger equation results in an `objective' reduction of the wave packet.

  2. Direct Observation of Anisotropic Carrier Transport in Organic Semiconductor by Time-Resolved Microscopic Optical Second-Harmonic Imaging

    NASA Astrophysics Data System (ADS)

    Manaka, Takaaki; Matsubara, Kohei; Abe, Kentaro; Iwamoto, Mitsumasa

    2013-10-01

    In-plane anisotropic carrier transport in single-crystalline grains of the dip-coated 6,13-bis(triisopropylsilylethynyl) (TIPS) pentacene film is studied by using the time-resolved microscopic optical second-harmonic generation (TRM-SHG). The TRM-SHG imaging directly visualizes the directional dependence of the carrier velocity, indicating the anisotropic carrier mobility of the TIPS pentacene single crystal. Results showed that the mobility anisotropy is smaller than that obtained from the current-voltage (I-V) characteristics. Overestimation of the mobility anisotropy using the I-V characteristics, compared with that obtained from the TRM-SHG measurement, is ascribed to the effect of the grain boundary on the carrier transport.

  3. The interstellar medium in the direction of the Crab Nebula - Reconciling soft X-ray and radio observations

    Microsoft Academic Search

    S. K. Ride; A. B. C. Walker Jr.

    1977-01-01

    The total soft X-ray photoabsorption cross section of the interstellar medium (ISM) in the direction of the Crab Nebula is computed on the basis of a two-phase model of the ISM. This cross section is used to reanalyze Copernicus data on the X-ray spectrum of the Crab between 0.7 and 1.5 keV. The total hydrogen column density along the line

  4. Direct observation of tetravalent cerium in ferromanganese nodules and crusts by X-ray-absorption near-edge structure (XANES)

    Microsoft Academic Search

    Yoshio Takahashi; Hiroshi Shimizu; Akira Usui; Hiroyuki Kagi; Masaharu Nomura

    2000-01-01

    X-ray-absorption near-edge structure (XANES) was successfully applied for the direct determination of Ce valence in hydrogenetic ferromanganese nodules (two samples) and crust (one sample). Rare earth element (REE) patterns of the hydrogenetic ferromanganese nodules and crust recovered from the Pacific Ocean show large positive Ce anomalies, especially when normalized to seawater. Despite some disadvantages in the spectroscopic analysis of Ce

  5. A review of performance characteristics of satellite antennas and some observations on future directions in satellite antenna design

    NASA Technical Reports Server (NTRS)

    Mittra, R.; Galindo-Israel, V.; Bathker, D. A.; Moule, W. N.

    1977-01-01

    A general review of the state-of-the-art and new directions in research and development of spacecraft antennas is presented. Three general classes of antennas are discussed: phased arrays, lenses (dielectric and waveguide), and reflector antennas. Presently, the antenna with most applications is the reflector with considerable research being performed to improve its scan and multiple beam characteristics. Future applications for spacecraft antennas and research goals to meet these projected needs also are discussed.

  6. Observation of direct-photon collective flow in sqrt(s_NN)=200 GeV Au+Au collisions

    Microsoft Academic Search

    A. Adare; S. Afanasiev; C. Aidala; N. N. Ajitanand; Y. Akiba; H. Al-Bataineh; J. Alexander; K. Aoki; Y. Aramaki; E. T. Atomssa; R. Averbeck; T. C. Awes; B. Azmoun; V. Babintsev; M. Bai; G. Baksay; L. Baksay; K. N. Barish; B. Bassalleck; A. T. Basye; S. Bathe; V. Baublis; C. Baumann; A. Bazilevsky; S. Belikov; R. Belmont; R. Bennett; A. Berdnikov; Y. Berdnikov; A. A. Bickley; J. S. Bok; K. Boyle; M. L. Brooks; H. Buesching; V. Bumazhnov; G. Bunce; S. Butsyk; C. M. Camacho; S. Campbell; C.-H. Chen; C. Y. Chi; M. Chiu; I. J. Choi; R. K. Choudhury; P. Christiansen; T. Chujo; P. Chung; O. Chvala; V. Cianciolo; Z. Citron; B. A. Cole; M. Connors; P. Constantin; M. Csanád; T. Csörgo; T. Dahms; S. Dairaku; I. Danchev; K. Das; A. Datta; G. David; A. Denisov; A. Deshpande; E. J. Desmond; O. Dietzsch; A. Dion; M. Donadelli; O. Drapier; A. Drees; K. A. Drees; J. M. Durham; A. Durum; D. Dutta; S. Edwards; Y. V. Efremenko; F. Ellinghaus; T. Engelmore; A. Enokizono; H. En'yo; S. Esumi; B. Fadem; D. E. Fields; M. Finger; M. Finger Jr.; F. Fleuret; S. L. Fokin; Z. Fraenkel; J. E. Frantz; A. Franz; A. D. Frawley; K. Fujiwara; Y. Fukao; T. Fusayasu; I. Garishvili; A. Glenn; H. Gong; M. Gonin; Y. Goto; R. Granier de Cassagnac; N. Grau; S. V. Greene; M. Grosse Perdekamp; T. Gunji; H.-Å. Gustafsson; J. S. Haggerty; K. I. Hahn; H. Hamagaki; J. Hamblen; R. Han; J. Hanks; E. P. Hartouni; E. Haslum; R. Hayano; X. He; M. Heffner; T. K. Hemmick; T. Hester; J. C. Hill; M. Hohlmann; W. Holzmann; K. Homma; B. Hong; T. Horaguchi; D. Hornback; S. Huang; T. Ichihara; R. Ichimiya; J. Ide; Y. Ikeda; K. Imai; M. Inaba; D. Isenhower; M. Ishihara; T. Isobe; M. Issah; A. Isupov; D. Ivanischev; B. V. Jacak; J. Jia; J. Jin; B. M. Johnson; K. S. Joo; D. Jouan; D. S. Jumper; F. Kajihara; S. Kametani; N. Kamihara; J. Kamin; J. H. Kang; J. Kapustinsky; K. Karatsu; D. Kawall; M. Kawashima; A. V. Kazantsev; T. Kempel; A. Khanzadeev; K. M. Kijima; B. I. Kim; D. H. Kim; D. J. Kim; E. Kim; S. H. Kim; Y. J. Kim; E. Kinney; K. Kiriluk; Á. Kiss; E. Kistenev; L. Kochenda; B. Komkov; M. Konno; J. Koster; D. Kotchetkov; A. Kozlov; A. Král; A. Kravitz; G. J. Kunde; K. Kurita; M. Kurosawa; Y. Kwon; G. S. Kyle; R. Lacey; Y. S. Lai; J. G. Lajoie; A. Lebedev; D. M. Lee; J. Lee; K. Lee; K. S. Lee; M. J. Leitch; M. A. L. Leite; E. Leitner; B. Lenzi; X. Li; P. Liebing; L. A. Linden Levy; T. Liska; A. Litvinenko; H. Liu; M. X. Liu; B. Love; R. Luechtenborg; D. Lynch; C. F. Maguire; Y. I. Makdisi; A. Malakhov; M. D. Malik; V. I. Manko; E. Mannel; Y. Mao; H. Masui; F. Matathias; M. McCumber; P. L. McGaughey; N. Means; B. Meredith; Y. Miake; A. C. Mignerey; P. Mikes; K. Miki; A. Milov; M. Mishra; J. T. Mitchell; A. K. Mohanty; Y. Morino; A. Morreale; D. P. Morrison; T. V. Moukhanova; J. Murata; S. Nagamiya; J. L. Nagle; M. Naglis; M. I. Nagy; I. Nakagawa; Y. Nakamiya; T. Nakamura; K. Nakano; J. Newby; M. Nguyen; R. Nouicer; A. S. Nyanin; E. O'Brien; S. X. Oda; C. A. Ogilvie; M. Oka; K. Okada; Y. Onuki; A. Oskarsson; M. Ouchida; K. Ozawa; R. Pak; V. Pantuev; V. Papavassiliou; I. H. Park; S. K. Park; W. J. Park; S. F. Pate; H. Pei; J.-C. Peng; H. Pereira; V. Peresedov; D. Yu. Peressounko; C. Pinkenburg; R. P. Pisani; M. Proissl; M. L. Purschke; A. K. Purwar; H. Qu; J. Rak; A. Rakotozafindrabe; I. Ravinovich; K. F. Read; K. Reygers; V. Riabov; Y. Riabov; E. Richardson; D. Roach; G. Roche; S. D. Rolnick; M. Rosati; C. A. Rosen; S. S. E. Rosendahl; P. Rosnet; P. Rukoyatkin; P. Ruzicka; B. Sahlmueller; N. Saito; T. Sakaguchi; K. Sakashita; V. Samsonov; S. Sano; T. Sato; S. Sawada; K. Sedgwick; J. Seele; R. Seidl; A. Yu. Semenov; R. Seto; D. Sharma; I. Shein; T.-A. Shibata; K. Shigaki; M. Shimomura; K. Shoji; P. Shukla; A. Sickles; C. L. Silva; D. Silvermyr; C. Silvestre; K. S. Sim; B. K. Singh; C. P. Singh; V. Singh; M. Slunecka; R. A. Soltz; W. E. Sondheim; S. P. Sorensen; I. V. Sourikova; N. A. Sparks; P. W. Stankus; E. Stenlund; S. P. Stoll; T. Sugitate; A. Sukhanov; J. Sziklai; E. M. Takagui; A. Taketani; R. Tanabe; Y. Tanaka; K. Tanida; M. J. Tannenbaum; S. Tarafdar; A. Taranenko; P. Tarján; H. Themann; T. L. Thomas; M. Togawa; A. Toia; L. Tomásek; H. Torii; R. S. Towell; I. Tserruya; Y. Tsuchimoto; C. Vale; H. Valle; H. W. van Hecke; E. Vazquez-Zambrano; A. Veicht; J. Velkovska; R. Vértesi; A. A. Vinogradov; M. Virius; V. Vrba; E. Vznuzdaev; X. R. Wang; D. Watanabe; K. Watanabe; Y. Watanabe; F. Wei; R. Wei; J. Wessels; S. N. White; D. Winter; J. P. Wood; C. L. Woody; R. M. Wright; M. Wysocki; W. Xie; Y. L. Yamaguchi; K. Yamaura; R. Yang; A. Yanovich; J. Ying; S. Yokkaichi; Z. You; G. R. Young; I. Younus; I. E. Yushmanov; W. A. Zajc; C. Zhang; S. Zhou; L. Zolin

    2011-01-01

    The second Fourier component v_2 of the azimuthal anisotropy with respect to the reaction plane was measured for direct photons at midrapidity and transverse momentum (p_T) of 1--13 GeV\\/c in Au+Au collisions at sqr(s_NN)=200 GeV. Previous measurements of this quantity for hadrons with p_T 6 GeV\\/c a reduced anisotropy is interpreted in terms of a path-length dependence for parton energy

  7. A search for anisotropy in the arrival directions of ultra-high-energy cosmic rays observed by the High Resolution Fly's Eye detector

    NASA Astrophysics Data System (ADS)

    Stokes, Benjamin Taylor

    2006-06-01

    Although the existence of cosmic rays with energies extending well above 10^19 eV has been confirmed, their origin remains one of the most important questions in astro-particle physics today. The High Resolution Fly's Eye Detector (HiRes) detects Ultra High Energy Cosmic Rays (UHECRs) by employing the air- fluorescence technique to observe Extensive Air Showers (EAS) in the atmosphere over Dugway, Utah. It has been collecting data since May 1997 during which time over 1500 events with energies greater than 10 18.5 eV have been observed in monocular mode. These events are characterized by arrival directions with asymmetric uncertainties, which are explored in detail for this study. Multiple methods are developed and utilized to search for anisotropies in the arrival directions. A primary emphasis is placed upon previous reported observations that suggested small-scale clustering and global dipole biases. Additionally a new method for searching for anisotropies is explored. While all conclusions are statistically limited in their applicability, the sensitivities are shown to be compatible with prior experiments. However, all evidence to date on the arrival directions of the UHECRs observed by HiRes in monocular mode is consistent with an isotropic distribution.

  8. Direct observation of low energy nuclear spin excitations in HoCrO3 by high resolution neutron spectroscopy.

    PubMed

    Chatterji, T; Jalarvo, N; Kumar, C M N; Xiao, Y; Brückel, Th

    2013-07-17

    We have investigated low energy nuclear spin excitations in the strongly correlated electron compound HoCrO3. We observe clear inelastic peaks at E = 22.18 ± 0.04 ?eV in both energy loss and gain sides. The energy of the inelastic peaks remains constant in the temperature range 1.5-40 K at which they are observed. The intensity of the inelastic peak increases at first with increasing temperature and then decreases at higher temperatures. The temperature dependence of the energy and intensity of the inelastic peaks is very unusual compared to that observed in other Nd, Co, V and also simple Ho compounds. Huge quasielastic scattering appears at higher temperatures presumably due to the fluctuating electronic moments of the Ho ions that get increasingly disordered at higher temperatures. The strong quasielastic scattering may also originate in the first Ho crystal-field excitations at about 1.5 meV. PMID:23779198

  9. Direct observation of liposome uptake by leukocytes in vivo in skin blood vessels using intravital fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Devoisselle, Jean-Marie; Mordon, Serge R.; Begu, Sylvie; Desmettre, Thomas

    2000-04-01

    This study aimed to observe liposome uptake by leukocytes in vivo. The study was performed on skin by using a dorsal skin-fold chamber implanted in golden hamsters using intravital microscopy. 5,6-CF-encapsulated PEGylated liposomes were injected intravenously. The skin microcirculation was observed with an intravital Eclipse E800 Nikon microscope fitted with a Xenon light source and an epi-fluorescence assembly. An ultra-high sensitivity video-camera mounted on the microscope projected the image onto a monitor, and the images were recorded for playback analysis with a digital video cassette recorder. An acute inflammatory response was obtained by removing one complete layer of skin and the underlying fascia and avascular tissue on the opposing side of the flap corresponding to an area equivalent to the window aperture. Using these model and set-up, leukocyte rolling and adhesion were easily observed and the entry of PEGylated liposomes into hamster blood leukocytes was studied for a period of 6 hours. PEGylated liposomes were clearly identified alone inside the blood flow and inside the leukocytes as soon as the inflammatory reaction appeared. This study shows for the first time that blood leukocytes in their natural milieu of whole blood are capable of interacting with, and taking up liposomes. This observation is in accordance with previous in vitro studies.

  10. Heat transfer characteristics of the two-phase closed thermosyphon (wickless heat pipe) including direct flow observation. Final report

    Microsoft Academic Search

    F. E. Andros; L. W. Florschuetz

    1980-01-01

    In Part I a visual study of an annular two-phase closed thermosyphon (wickless heat pipe) is reported. The heat transfer surface was stainless steel. Working fluids were Freon-113, ethanol, and water. Photographs of pertinent phenomena are included. The visual observations were used to interpret the measured heat transfer characteristics. For small and intermediate liquid fill quantities four flow regimes were

  11. Direct Observation of Self-Similarity in Evolution of Transient Stimulated Raman Scattering in Gas-Filled Photonic Crystal Fibers

    Microsoft Academic Search

    A. Nazarkin; A. Abdolvand; A. V. Chugreev; P. St. J. Russell

    2010-01-01

    A unique characteristic of transient stimulated Raman scattering, in which the spatiotemporal evolution of the fields and the molecular excitation follow a universal self-similarity law, is observed in gas-filled photonic crystal fibers. As the input laser power is increased, the coupled system ``optical fields + molecular excitation'' goes through the same phases of time evolution but at a higher rate.

  12. Direct observation of sub-picosecond equilibration of excitation energy in the light-harvesting antenna of Rhodospirillum rubrum.

    PubMed Central

    Visser, H M; Somsen, O J; van Mourik, F; Lin, S; van Stokkum, I H; van Grondelle, R

    1995-01-01

    Excitation energy transfer in the light-harvesting antenna of Rhodospirillum rubrum was studied at room temperature using sub-picosecond transient absorption measurements. Upon excitation of Rs. rubrum membranes with a 200 fs, 600 nm laser flash in the Qx transition of the bacteriochlorophyll-a (BChl-a) absorption, the induced transient absorption changes in the Qy region were monitored. In Rs. rubrum membranes the observed delta OD spectrum exhibits ground state bleaching, excited state absorption and stimulated emission. Fast Qx --> Qy relaxation occurs in approximately 100-200 fs as reflected by the building up of stimulated emission. An important observation is that the zero-crossing of the transient difference absorption (delta OD) spectrum exhibits a dynamic redshift from 863 to 875 nm that can be described with by a single exponential with 325 fs time constant. The shape of the transient difference spectrum observed in a purified subunit of the core light-harvesting antenna, B820, consisting of only a single interacting pair of BChl-as, is similar to the spectrum observed in Rs. rubrum membranes and clearly different from the spectrum of BChl-a in a protein/detergent mixture. In the B820 and monomeric BChl-a preparations the 100-200 fs Qx --> Qy relaxation is still observed, but the dynamic redshift of the delta OD spectrum is absent. The spectral kinetics observed in the Rs. rubrum membranes are interpreted in terms of the dynamics of excitation equilibration among the antenna subunits that constitute the inhomogeneously broadened antenna. A simulation of this process using a set of reasonable physical parameters is consistent with an average hopping time in the core light harvesting of 220-270 fs, resulting in an average single-site excitation lifetime of 50-70 fs. The observed rate of this equilibration process is in reasonable agreement with earlier estimations for the hopping time from more indirect measurements. The implications of the findings for the process of excitation trapping by reaction centers will be discussed. Images FIGURE 7 PMID:8519962

  13. Temporal observation of potential structure by direct measurement of loss-cone boundaries in the tandem mirror GAMMA-10

    SciTech Connect

    Ishii, Kameo; Takahashi, Toshiki; Abe, Akira; Katanuma, Isao; Itakura, Akiyosi; Ichimura, Makoto; Kiwamoto, Yasuhito; Yatsu, Kiyoshi; Tamano, Teruo [Univ. of Tsukuba, Ibaraki (Japan)

    1995-04-01

    Loss-cone boundaries have been directly measured using a newly developed diagnostic device in the tandem mirror GAMMA 10. Double loss boundaries clearly appeared in the velocity space of the end-loss ions in the experiment without plug ECRH, and upon turning on the ECRH, the double boundaries changed to a single loss boundary. From a microscopic viewpoint of the ion distribution function, it was verified that plug potential was created turning on ERCH without producing sloshing ions by neutral beam injection. Time evolution of plasma potentials is discussed. 4 refs., 6 figs.

  14. Knocking Combustion Observed in a Spark-Ignition Engine with Simultaneous Direct and Schlieren High-Speed Motion Pictures and Pressure Records

    NASA Technical Reports Server (NTRS)

    Osterstrom, Gordon E

    1948-01-01

    Simultaneous direct and Schlieren photographs at 40,000 frames per second and correlated pressure records were taken of knocking combustion in a special spark-ignition engine to ascertain the intensity of certain end-zone reactions previously noted from Schlieren photography alone. A violent propagated homogeneous autoignition, or a similar phenomenon, previously observed, was again observed. The pressure records show autoignition of varying violence before the passage of a probable detonation wave. Extensive autoignition without occurrence of gas vibrations was seen in one explosion.

  15. Direct observation of fatigue in epitaxially grown Pb(Zr,Ti)O3 thin films using second harmonic piezoresponse force microscopy

    NASA Astrophysics Data System (ADS)

    Murari, Nishit M.; Hong, Seungbum; Lee, Ho Nyung; Katiyar, Ram. S.

    2011-08-01

    Here, we present a direct observation of fatigue phenomena in epitaxially grown Pb(Zr0.2Ti0.8)O3 (PZT) thin films using second harmonic piezoresponse force microscopy (SH-PFM). We observed strong correlation between the SH-PFM amplitude and phase signals with the remnant piezoresponse at different switching cycles. The SH-PFM results indicate that the average fraction of switchable domains decreases globally and the phase delays of polarization switching differ locally. In addition, we found that the fatigue developed uniformly over the whole area without developing region-by-region suppression of switchable polarization as in polycrystalline PZT thin films.

  16. Direct observation of oil consumption mechanisms in a production spark ignition engine using fluorescence techniques. Master's thesis

    SciTech Connect

    Lusted, R.M.

    1994-05-01

    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% 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.

  17. Observation of Anisotropy in the Arrival Directions of Galactic Cosmic Rays at Multiple Angular Scales with IceCube

    NASA Astrophysics Data System (ADS)

    Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Altmann, D.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; BenZvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Brown, A. M.; Buitink, S.; Caballero-Mora, K. S.; Carson, M.; Chirkin, D.; Christy, B.; Clem, J.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; D'Agostino, M. V.; Danninger, M.; Daughhetee, J.; Davis, J. C.; De Clercq, C.; Demirörs, L.; Denger, T.; Depaepe, O.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; DeYoung, T.; Díaz-Vélez, J. C.; Dierckxsens, M.; Dreyer, J.; Dumm, J. P.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feintzeig, J.; Feusels, T.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Gora, D.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gurtner, M.; Ha, C.; Hajismail, A.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Heinen, D.; Helbing, K.; Herquet, P.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Homeier, A.; Hoshina, K.; Hubert, D.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Joseph, J. M.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Krings, T.; Kroll, G.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Lafebre, S.; Laihem, K.; Landsman, H.; Larson, M. J.; Lauer, R.; Lünemann, J.; Madajczyk, B.; Madsen, J.; Majumdar, P.; Marotta, A.; Maruyama, R.; Mase, K.; Matis, H. S.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Middell, E.; Milke, N.; Miller, J.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nießen, P.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Ono, M.; Panknin, S.; Paul, L.; Pérez de los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, C. C.; Price, P. B.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Rodrigues, J. P.; Roth, P.; Rothmaier, F.; Rott, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Schmidt, T.; Schönwald, A.; Schukraft, A.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Slipak, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stephens, G.; Stezelberger, T.; Stokstad, R. G.; Stössl, A.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Stür, M.; Sullivan, G. W.; Swillens, Q.; Taavola, H.; Taboada, I.; Tamburro, A.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Tosi, D.; Tur?an, D.; van Eijndhoven, N.; Vandenbroucke, J.; Van Overloop, A.; van Santen, J.; Vehring, M.; Voge, M.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, C.; Xu, X. W.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.; Zoll, M.; IceCube Collaboration

    2011-10-01

    Between 2009 May and 2010 May, the IceCube neutrino detector at the South Pole recorded 32 billion muons generated in air showers produced by cosmic rays with a median energy of 20 TeV. With a data set of this size, it is possible to probe the southern sky for per-mil anisotropy on all angular scales in the arrival direction distribution of cosmic rays. Applying a power spectrum analysis to the relative intensity map of the cosmic ray flux in the southern hemisphere, we show that the arrival direction distribution is not isotropic, but shows significant structure on several angular scales. In addition to previously reported large-scale structure in the form of a strong dipole and quadrupole, the data show small-scale structure on scales between 15° and 30°. The skymap exhibits several localized regions of significant excess and deficit in cosmic ray intensity. The relative intensity of the smaller-scale structures is about a factor of five weaker than that of the dipole and quadrupole structure. The most significant structure, an excess localized at (right ascension ? = 122fdg4 and declination ? = -47fdg4), extends over at least 20° in right ascension and has a post-trials significance of 5.3?. The origin of this anisotropy is still unknown.

  18. 42 CFR 61.8 - Benefits: Stipends; dependency allowances; travel allowances; vacation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Benefits: Stipends; dependency allowances; travel allowances; vacation. 61.8 Section 61.8 Public Health...Benefits: Stipends; dependency allowances; travel allowances; vacation. Individuals awarded regular...

  19. 42 CFR 61.8 - Benefits: Stipends; dependency allowances; travel allowances; vacation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Benefits: Stipends; dependency allowances; travel allowances; vacation. 61.8 Section 61.8 Public Health...Benefits: Stipends; dependency allowances; travel allowances; vacation. Individuals awarded regular...

  20. 42 CFR 61.8 - Benefits: Stipends; dependency allowances; travel allowances; vacation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Benefits: Stipends; dependency allowances; travel allowances; vacation. 61.8 Section 61.8 Public Health...Benefits: Stipends; dependency allowances; travel allowances; vacation. Individuals awarded regular...

  1. 42 CFR 61.8 - Benefits: Stipends; dependency allowances; travel allowances; vacation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Benefits: Stipends; dependency allowances; travel allowances; vacation. 61.8 Section 61.8 Public Health...Benefits: Stipends; dependency allowances; travel allowances; vacation. Individuals awarded regular...

  2. Observation of heavy- and light-hole split direct bandgap photoluminescence from tensile-strained GeSn (0.03% Sn)

    NASA Astrophysics Data System (ADS)

    Harris, Thomas R.; Yeo, Yung Kee; Ryu, Mee-Yi; Beeler, Richard T.; Kouvetakis, John

    2014-09-01

    Temperature- (T-) and laser power-dependent photoluminescence (PL) measurements have been made for the tensile-strained, undoped GeSn (0.03% Sn) film grown on Si substrate. The PL results show not only clear strain-split direct bandgap transitions to the light-hole (LH) and heavy-hole (HH) bands at energies of 0.827 and 0.851 eV at 10 K, respectively, but also clearly show both strong direct and indirect bandgap related PL emissions at almost all temperatures, which are rarely observed. This split of PL emissions can be directly observed only at low T and moderate laser power, and the two PL peaks merge into one broad PL peak at room temperature, which is mainly due to the HH PL emission rather than LH transition. The evolution of T-dependent PL results also clearly show the competitive nature between the direct and indirect bandgap related PL transitions as T changes. The PL analysis also indicates that the energy gap reduction in ? valley could be larger, whereas the bandgap reduction in L valley could be smaller than the theory predicted. As a result, the separation energy between ? and L valleys (˜86 meV at 300 K) is smaller than theory predicted (125 meV) for this Ge-like sample, which is mainly due to the tensile strain. This finding strongly suggests that the indirect-to-direct bandgap transition of Ge1-ySny could be achieved at much lower Sn concentration than originally anticipated if one utilizes the tensile strain properly. Thus, Ge1-ySny alloys could be attractive materials for the fabrication of direct bandgap Si-based light emitting devices.

  3. Direct observation and measurements of neutron-induced deep levels responsible for N eff changes in high-resistivity silicon detectors using TCT

    Microsoft Academic Search

    Z. Li; C. J Li; V. Eremin; E. Verbitskaya

    1997-01-01

    Neutron-irradiation-induced deep levels responsible for changes of the space charge concentration Neff in high-resistivity silicon detectors have been revealed directly using the Transient Current Technique (TCT). It has been observed by TCT that the absolute value and sign of Neff experience changes due to the trapping of non-equilibrium free carriers generated near the surface (about 5 ?m depth into the

  4. The interstellar turbulent plasma spectrum in the direction to PSR B1642-03 from multi-frequency observations of interstellar scintillation

    Microsoft Academic Search

    T. V. Smirnova; V. I. Shishov; W. Sieber; D. R. Stinebring; V. M. Malofeev; V. A. Potapov; S. A. Tyul'Bashev; A. Jessner; R. Wielebinski

    2006-01-01

    Multi-frequency observations of interstellar scintillation toward the pulsar PSR B1642-03 were analyzed to estimate the spectrum of interstellar plasma inhomogeneities in the direction of this pulsar. Using data over the frequency range from 103 MHz to 5 GHz, we constructed the composite structure function (SF) of phase fluctuations, which covers a corresponding wide range of turbulence scales. The structure function

  5. A High shear stress segment along the San Andreas Fault: Inferences based on near-field stress direction and stress magnitude observations in the Carrizo Plain Area

    SciTech Connect

    Castillo, D. A., [Department of Geology and Geophysics, University of Adelaide (Australia); Younker, L.W. [Lawrence Livermore National Lab., CA (United States)

    1997-01-30

    Nearly 200 new in-situ determinations of stress directions and stress magnitudes near the Carrizo plain segment of the San Andreas fault indicate a marked change in stress state occurring within 20 km of this principal transform plate boundary. A natural consequence of this stress transition is that if the observed near-field ``fault-oblique`` stress directions are representative of the fault stress state, the Mohr-Coulomb shear stresses resolved on San Andreas sub-parallel planes are substantially greater than previously inferred based on fault-normal compression. Although the directional stress data and near-hydrostatic pore pressures, which exist within 15 km of the fault, support a high shear stress environment near the fault, appealing to elevated pore pressures in the fault zone (Byerlee-Rice Model) merely enhances the likelihood of shear failure. These near-field stress observations raise important questions regarding what previous stress observations have actually been measuring. The ``fault-normal`` stress direction measured out to 70 km from the fault can be interpreted as representing a comparable depth average shear strength of the principal plate boundary. Stress measurements closer to the fault reflect a shallower depth-average representation of the fault zone shear strength. If this is true, only stress observations at fault distances comparable to the seismogenic depth will be representative of the fault zone shear strength. This is consistent with results from dislocation monitoring where there is pronounced shear stress accumulation out to 20 km of the fault as a result of aseismic slip within the lower crust loading the upper locked section. Beyond about 20 km, the shear stress resolved on San Andreas fault-parallel planes becomes negligible. 65 refs., 15 figs.

  6. Direct observations of Ge2Sb2Te5 recording marks in the phase-change disk

    NASA Astrophysics Data System (ADS)

    Naito, Muneyuki; Ishimaru, Manabu; Hirotsu, Yoshihiko; Kojima, Rie; Yamada, Noboru

    2010-05-01

    Atomistic structures of the Ge2Sb2Te5 thin film in the real phase-change disk have been investigated using transmission electron microscopy (TEM). As-deposited amorphous Ge2Sb2Te5 films were laser-irradiated for initialization (crystallization) and recording. Cross-sectional TEM observations revealed that the recording mark was fully amorphized by laser irradiation. A slight difference between the as-deposited and the laser irradiation-induced amorphous Ge2Sb2Te5 was observed in the intensity profile of nanobeam electron diffraction patterns and atomic pair distribution functions. This difference was attributed to structural relaxation of amorphous Ge2Sb2Te5, which gives rise to the alteration of chemical order.

  7. Direct Observation of a Breaking Unsteady Lee Wave Generated by Diurnal Tides and an Estimate of its Global Occurrence

    NASA Astrophysics Data System (ADS)

    Nakamura, Tomohiro; Isoda, Yutaka; Mitsudera, Humio; Takagi, Shogo; Nagasawa, Maki; Abe, Shoko

    2010-05-01

    Diapycnal mixing caused through breaking of large-amplitude internal lee waves generated by subinertial diurnal tides, which are modulated with the 18.6-year nodal cycle, is hypothesized to be fundamental to both the intermediate-layer ventilation and the bi-decadal oscillation around the North Pacific Ocean. The first observational evidence of such wave breaking is presented here. The breaking wave observed had ~ 200 m height and ~ 1 km width. Its associated diapycnal mixing was estimated to be ~ 1.5 × 104 cm2/s, while typical values found in the open oceans are O(0.1 cm2/s). Our estimate suggests that a similar mixing process occurs globally, particularly around the Pacific and Antarctic Oceans.

  8. Mixing state of aerosols and direct observation of carbonaceous and marine coatings on African dust by individual particle analysis

    Microsoft Academic Search

    Karine Deboudt; Pascal Flament; Marie Choël; Alexandre Gloter; Sophie Sobanska; Christian Colliex

    2010-01-01

    The mixing state of aerosols collected at M'Bour, Senegal, during the Special Observing Period conducted in January–February 2006 (SOP-0) of the African Monsoon Multidisciplinary Analysis project (AMMA), was studied by individual particle analysis. The sampling location on the Atlantic coast is particularly adapted for studying the mixing state of tropospheric aerosols since it is (1) located on the path of

  9. Direct observation of microcirculatory parameters in rat brain after local exposure to radio-frequency electromagnetic field

    Microsoft Academic Search

    S. Hirota; M. Matsuura; H. Masuda; A. Ushiyama; K. Wake; S. Watanabe; M. Taki; C. Ohkubo

    2009-01-01

    A cranial window method modified for our experiment enabled to observe the cerebral microcirculation including the blood-brain\\u000a barrier permeability after a local expose to radio-frequency electromagnetic fields with a monopole antenna in rats. The present\\u000a report reviews our recent publications that reported no noticeable changes in the cerebral microcirculatory parameters due\\u000a to RF-EMF exposure.

  10. Direct observation of ruthenium complex adsorption at the glass\\/water interface studied by optical second harmonic generation

    Microsoft Academic Search

    Yasuhiro Yamada; Takashi Nakano; Keiji Yamada; Taku Matsuo; Sunao Yamada

    2000-01-01

    Adsorption behaviors of an amphiphilic ruthenium (II) tris(2,2?-bipyridine) derivative (Ru-complex) at the glass\\/water interface have been investigated by using the in situ optical second harmonic generation (SHG) technique. A clear SHG signal was observed when an alkaline-treated (hydrophilic surface) glass substrate was immersed into an aqueous Ru-complex solution, but the signal decreased as the electrolyte concentration increased. The SHG signal

  11. Direct observation of defects in triple-junction solar cell by optical deep-level transient spectroscopy

    Microsoft Academic Search

    Xi Zhang; Jianmin Hu; Yiyong Wu; Fang Lu

    2009-01-01

    The optical deep-level transient spectroscopy (ODLTS) technique has been used to measure defects in GaInP\\/GaAs\\/Ge multi-junction solar cells for the first time. Three modes of ODLTS were used to detect defects in the top two sub-cells of this triple-junction cell separately. For one non-irradiated sample, only one level in the top sub-cell at low temperature was observed. Three samples were

  12. Direct observation of strain fields in epitaxial growth Fe3O4 thin films on MgO substrates

    Microsoft Academic Search

    Y. X. Chen; C. Chen; W. L. Zhou; Z. J. Wang; J. Tang; D. X. Wang; J. M. Daughton

    2004-01-01

    Fe3O4 thin films with a thickness of about 140 nm have been deposited on MgO (001) substrates by reactive sputtering. Microstructural studies indicated that monocrystalline Fe3O4 thin films were epitaxially grown on the MgO substrates with a cubic-on-cubic orientation relationship with respect to the substrates. Strain field due to slight lattice mismatch between the films and substrates was observed. The

  13. Observation of Large CP Violation and Evidence for Direct CP Violation in B0-->pi+pi- Decays

    Microsoft Academic Search

    K. Abe; N. Abe; T. Abe; I. Adachi; H. Aihara; K. Akai; M. Akatsu; M. Akemoto; Y. Asano; T. Aso; V. Aulchenko; T. Aushev; A. M. Bakich; Y. Ban; S. Banerjee; A. Bay; I. Bedny; I. Bizjak; A. Bondar; A. Bozek; M. Bracko; T. E. Browder; Y. Chao; K.-F. Chen; B. G. Cheon; R. Chistov; S.-K. Choi; Y. Choi; A. Chuvikov; S. Cole; M. Danilov; J. Dragic; A. Drutskoy; S. Eidelman; V. Eiges; Y. Enari; D. Epifanov; J. Flanagan; K. Furukawa; N. Gabyshev; A. Garmash; T. Gershon; B. Golob; J. Haba; K. Hara; N. C. Hastings; H. Hayashii; M. Hazumi; L. Hinz; T. Hokuue; Y. B. Hsiung; W.-S. Hou; H.-C. Huang; T. Iijima; H. Ikeda; K. Inami; A. Ishikawa; H. Ishino; R. Itoh; H. Iwasaki; M. Iwasaki; Y. Iwasaki; H. Kakuno; T. Kamitani; J. H. Kang; J. S. Kang; P. Kapusta; S. U. Kataoka; N. Katayama; H. Kichimi; T. Kawasaki; A. Kibayashi; H. J. Kim; J. H. Kim; S. K. Kim; K. Kinoshita; P. Koppenburg; S. Korpar; P. Krizan; P. Krokovny; S. Kumar; A. Kuzmin; Y.-J. Kwon; J. S. Lange; G. Leder; S. H. Lee; Y.-J. Lee; T. Lesiak; J. Li; A. Limosani; S.-W. Lin; D. Liventsev; J. MacNaughton; F. Mandl; D. Marlow; H. Matsumoto; T. Matsumoto; A. Matyja; S. Michizono; T. Mimashi; W. Mitaroff; K. Miyabayashi; H. Miyake; H. Miyata; D. Mohapatra; G. R. Moloney; A. Murakami; T. Nagamine; Y. Nagasaka; T. Nakadaira; T. T. Nakamura; E. Nakano; M. Nakao; H. Nakazawa; Z. Natkaniec; K. Neichi; S. Nishida; O. Nitoh; S. Noguchi; T. Nozaki; S. Ogawa; Y. Ogawa; K. Ohmi; T. Ohshima; N. Ohuchi; K. Oide; T. Okabe; S. Okuno; S. L. Olsen; W. Ostrowicz; H. Ozaki; P. Pakhlov; H. Palka; C. W. Park; N. Parslow; L. E. Piilonen; N. Root; M. Rozanska; H. Sagawa; Y. Sakai; O. Schneider; J. Schümann; C. Schwanda; A. J. Schwartz; S. Semenov; K. Senyo; H. Shibuya; T. Shidara; B. Shwartz; V. Sidorov; J. B. Singh; N. Soni; R. Stamen; S. Stanic; M. Staric; R. Sugahara; K. Sumisawa; T. Sumiyoshi; K. Suzuki; S. Suzuki; O. Tajima; F. Takasaki; K. Tamai; N. Tamura; M. Tanaka; M. Tawada; Y. Teramoto; T. Tomura; T. Tsuboyama; T. Tsukamoto; S. Uehara; T. Uglov; K. Ueno; Y. Unno; S. Uno; G. Varner; K. E. Varvell; C. C. Wang; M.-Z. Wang; Y. Watanabe; B. D. Yabsley; Y. Yamada; A. Yamaguchi; Y. Yamashita; M. Yamauchi; H. Yanai; Heyoung Yang; J. Ying; M. Yokoyama; M. Yoshida; Y. Yusa; C. C. Zhang; Z. P. Zhang; T. Ziegler; D. Zontar; D. Zürcher

    2004-01-01

    We report the first observation of CP violation in B0-->pi+pi- decays based on 152×106 upsilo(4S)-->BB¯ decays collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. We reconstruct a B0-->pi+pi- CP eigenstate and identify the flavor of the accompanying B meson from its decay products. From the distribution of the time intervals between the two B meson decay points,

  14. Direct radiative forcing of Saharan dust in the Mediterranean from measurements at Lampedusa Island and MISR space-borne observations

    Microsoft Academic Search

    D. Meloni; A. di Sarra; T. Di Iorio; G. Fiocco

    2004-01-01

    Ground-based observations were carried out at the island of Lampedusa, in the central Mediterranean, simultaneously to measurements of the Multiangle Imaging Spectro-Radiometer (MISR) instrument aboard the Terra satellite, in 2 days of July 2002 (14 and 16) when Saharan dust was present. Ground-based measurements include ultraviolet spectral irradiance; visible global and diffuse irradiances at several bands; aerosol optical depth in

  15. DIRECT SOLUTIONS OF THE MAXWELL EQUATIONS EXPLAIN OPPOSITION PHENOMENA OBSERVED FOR HIGH-ALBEDO SOLAR SYSTEM OBJECTS

    SciTech Connect

    Mishchenko, Michael I.; Liu Li [NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 (United States); Dlugach, Janna M.; Rosenbush, Vera K.; Kiselev, Nikolai N. [Main Astronomical Observatory of the National Academy of Sciences of Ukraine, 27 Zabolotny Street, 03680 Kyiv (Ukraine); Shkuratov, Yuri G., E-mail: mmishchenko@giss.nasa.go [Astronomical Institute of the Kharkiv National University, 35 Sumska Street, 61022 Kharkiv (Ukraine)

    2009-11-10

    Several spectacular backscattering effects observed for particulate planetary surfaces have been interpreted in terms of the effect of weak localization (WL) of electromagnetic waves. However, the interference concept of WL explicitly relies on the notion of phase of an electromagnetic wave and is strictly applicable only when particles forming the surface are widely separated. Therefore, one needs a definitive quantitative proof of the WL nature of specific optical effects observed for densely packed particulate media. We use numerically exact computer solutions of the Maxwell equations to simulate electromagnetic scattering by realistic models consisting of large numbers of randomly positioned, densely packed particles. By increasing the particle packing density from zero to approx40%, we track the onset and evolution of the full suite of backscattering optical effects predicted by the low-density theory of WL, including the brightness and polarization opposition effects (BOE and POE). We find that all manifestations of WL, except the circular polarization ratio and POE, are remarkably immune to packing-density effects. Even POE can survive packing densities typical of planetary regolith surfaces. Our numerical data coupled with the results of unique observations at near-backscattering geometries demonstrate that the BOE and POE detected simultaneously for high-albedo solar system objects are caused by the effect of WL.

  16. Heat transfer characteristics of the two-phase closed thermosyphon (wickless heat pipe) including direct flow observation

    NASA Astrophysics Data System (ADS)

    Andros, F. E.

    1980-12-01

    The two phase closed thermosyphon is a heat transfer device capable of transferring large quantities of heat from a source to a sink by taking advantage of the high heat transfer rates associated with the evaporation and condensation of a working fluid within the device. For small and intermediate fill quantities, four basic flow regimes were observed in the evaporator section of the thermosyphon during steady state operation with Freon 113 and ethanol: (1) a smooth continuous film with surface evaporation; (2) the breakdown of the smooth continuous film into a series of rivulets; (3) a wavy film with unstable rivulets; and (4) a wavy film with bubble nucleation occurring in the unstable rivulets. A fifth condition which was observed with all fluids was a dry out (heat transfer limit) where some portion of the evaporator ceases to be cooled effectively by the falling film and rivulets, resulting in a wall temperature excursion or critical condition. Three types of dry out were observed. In addition to the visual device used, a stainless steel tubular opaque device was fabricated and is heat transfer characteristics evaluated using Freon 113 as a working fluid.

  17. Direct observation of reversible and irreversible stomatal responses of attached sunflower leaves to SO/sub 2/

    SciTech Connect

    Omasa, K.; Hashimoto, Y.; Kramer, P.J.; Strain, B.R.; Aiga, I.; Kondo, J.

    1985-09-01

    The effects of SO/sub 2/ on stomatal aperture of attached sunflower leaves were observed with a remote-control light microscope system that permitted continuous observation of stomatal responses over periods of several hours. The relationship between actual stomatal aperture and stomatal conductance, measured with a porometer, also was examined on leaves before and after exposure to SO/sub 2/. A distinction between uninjured and injured regions was clearly visible on leaves after exposure to 1.5 microliters per liter SO/sub 2/ for less than an hour. During the exposure, the mean value of apertures for many stomata, which indicates stomatal conductance and transpiration rate, tended to decrease simultaneously in the uninjured and injured regions. There was a good correlation between pore width and stomatal conductance measured with a porometer before exposure to SO/sub 2/. This correlation continued in leaves exposed to SO/sub 2/ until visible, irreversible injury occurred, but then it disappeared. The results of these experiments indicate the necessity of continuous observation of individual stomata under the microscope to understand the effects of air pollutants such as SO/sub 2/ on stomatal behavior.

  18. Direct observation and mechanism for enhanced field emission sites in platinum ion implanted/post-annealed ultrananocrystalline diamond films

    SciTech Connect

    Panda, Kalpataru, E-mail: panda@afm.eei.eng.osaka-u.ac.jp, E-mail: phy.kalpa@gmail.com; Inami, Eiichi; Sugimoto, Yoshiaki [Graduate School of Engineering, Osaka University, 2-1, Yamada-Oka, Suita, Osaka 565-0871 (Japan); Sankaran, Kamatchi J.; Tai, Nyan Hwa [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Lin, I-Nan, E-mail: inanlin@mail.tku.edu.tw [Department of Physics, Tamkang University, Tamsui 251, Taiwan (China)

    2014-10-20

    Enhanced electron field emission (EFE) properties for ultrananocrystalline diamond (UNCD) films upon platinum (Pt) ion implantation and subsequent post-annealing processes is reported, viz., low turn-on field of 4.17?V/?m with high EFE current density of 5.08?mA/cm{sup 2} at an applied field of 7.0?V/?m. Current imaging tunneling spectroscopy (CITS) mode in scanning tunneling spectroscopy directly revealed the increased electron emission sites density for Pt ion implanted/post-annealed UNCD films than the pristine one. The high resolution CITS mapping and local current–voltage characteristic curves demonstrated that the electrons are dominantly emitted from the diamond grain boundaries and Pt nanoparticles.

  19. Observation of Small-scale Anisotropy in the Arrival Direction Distribution of TeV Cosmic Rays with HAWC

    NASA Astrophysics Data System (ADS)

    Abeysekara, A. U.; Alfaro, R.; Alvarez, C.; Álvarez, J. D.; Arceo, R.; Arteaga-Velázquez, J. C.; Ayala Solares, H. A.; Barber, A. S.; Baughman, B. M.; Bautista-Elivar, N.; Belmont, E.; BenZvi, S. Y.; Berley, D.; Bonilla Rosales, M.; Braun, J.; Caballero-Mora, K. S.; Carramiñana, A.; Castillo, M.; Cotti, U.; Cotzomi, J.; de la Fuente, E.; De León, C.; DeYoung, T.; Diaz Hernandez, R.; Díaz-Vélez, J. C.; Dingus, B. L.; DuVernois, M. A.; Ellsworth, R. W.; Fiorino, D. W.; Fraija, N.; Galindo, A.; Garfias, F.; González, M. M.; Goodman, J. A.; Gussert, M.; Hampel-Arias, Z.; Harding, J. P.; Hüntemeyer, P.; Hui, C. M.; Imran, A.; Iriarte, A.; Karn, P.; Kieda, D.; Kunde, G. J.; Lara, A.; Lauer, R. J.; Lee, W. H.; Lennarz, D.; León Vargas, H.; Linnemann, J. T.; Longo, M.; Luna-García, R.; Malone, K.; Marinelli, A.; Marinelli, S. S.; Martinez, H.; Martinez, O.; Martínez-Castro, J.; Matthews, J. A. J.; McEnery, J.; Mendoza Torres, E.; Miranda-Romagnoli, P.; Moreno, E.; Mostafá, M.; Nellen, L.; Newbold, M.; Noriega-Papaqui, R.; Oceguera-Becerra, T.; Patricelli, B.; Pelayo, R.; Pérez-Pérez, E. G.; Pretz, J.; Rivière, C.; Rosa-González, D.; Ruiz-Velasco, E.; Ryan, J.; Salazar, H.; Salesa Greus, F.; Sandoval, A.; Schneider, M.; Sinnis, G.; Smith, A. J.; Sparks Woodle, K.; Springer, R. W.; Taboada, I.; Toale, P. A.; Tollefson, K.; Torres, I.; Ukwatta, T. N.; Villaseñor, L.; Weisgarber, T.; Westerhoff, S.; Wisher, I. G.; Wood, J.; Yodh, G. B.; Younk, P. W.; Zaborov, D.; Zepeda, A.; Zhou, H.; HAWC Collaboration

    2014-12-01

    The High-Altitude Water Cherenkov (HAWC) Observatory is sensitive to gamma rays and charged cosmic rays at TeV energies. The detector is still under construction, but data acquisition with the partially deployed detector started in 2013. An analysis of the cosmic-ray arrival direction distribution based on 4.9 × 1010 events recorded between 2013 June and 2014 February shows anisotropy at the 10-4 level on angular scales of about 10°. The HAWC cosmic-ray sky map exhibits three regions of significantly enhanced cosmic-ray flux; two of these regions were first reported by the Milagro experiment. A third region coincides with an excess recently reported by the ARGO-YBJ experiment. An angular power spectrum analysis of the sky shows that all terms up to l = 15 contribute significantly to the excesses.

  20. 46 CFR 154.428 - Allowable stress.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 2011-10-01 false Allowable stress. 154.428 Section 154.428...Membrane Tanks § 154.428 Allowable stress. The membrane tank and the supporting insulation must have allowable stresses that are specially approved by...