WorldWideScience

Sample records for revisited stm imaging

  1. STM topographical images of C60

    International Nuclear Information System (INIS)

    Wang, Z.; Zhang, P.; Moskovits, M.

    1991-01-01

    In this paper STM topographical images of C 60 are reported. The images are consistent with a molecule approximately 9 Angstrom in diameter possessing the now-famous soccer ball structure. With the molecule deposited on gold, its atomic structure is not resolved. On graphite the structure of the within the borders of the C 60 molecule is dominated by that of the graphite forming a moire-like pattern. Some evidence of atomic structure is seen in multilayers of C 60 where some five- and six-membered rings are visible. These may, however, be features of fragments of the fullerene rather than whole molecules

  2. Electronic structure and simulated STM images of non-honeycomb phosphorene allotropes

    Science.gov (United States)

    Kaur, Sumandeep; Kumar, Ashok; Srivastava, Sunita; Tankeshwar, K.

    2018-04-01

    We have investigated the electronic structure and simulated STM images of various non-honeycomb allotropes of phosphorene namely ɛ - P, ζ - P, η - P and θ - P, within combined density functional theory and Tersoff-Hamman approach. All these allotropes are found to be energetically stable and electronically semiconductingwith bandgap ranging between 0.5-1.2 eV. Simulated STM images show distinctly different features in terms of the topography. Different maximas in the distance-height profile indicates the difference in buckling of atoms in these allotropes. Distinctly different images obtained in this study may be useful to differentiate various allotropes that can serve as fingerprints to identify various allotropes during the synthesis of phosphorene.

  3. Electronic structure and STM imaging of the KBr-InSb interface

    Energy Technology Data Exchange (ETDEWEB)

    Ciochoń, Piotr, E-mail: ciochon.piotr@gmail.com; Olszowska, Natalia; Kołodziej, Jacek J.

    2017-07-01

    Highlights: • The structure of the InSb (001) surface covered with thin KBr layers is reported. • KBr growth does not perturb strongly the structure of a clean InSb surface. • A model of the system with KBr treated as a thin dielectric layer is proposed. • The atomic structure of the KBr-InSb interface is directly imaged using STM. - Abstract: We study the properties of the InSb (001) surface covered with ultrathin KBr films, with a thickness of 1–4 ML. KBr deposition does not strongly perturb the crystallographic structure of the InSb surface and the electronic structure of the substrate also remains unaffected by the overlayer. A simple model of the studied system is proposed, in which a thin KBr layer is treated as a dielectric film, modifying potential barrier for the electrons tunneling to/from the InSb substrate. Apparent step heights on the KBr film, measured using scanning tunneling microscope (STM), agree well with the predictions of the model and the atomically-resolved STM images show the structure of the InSb-KBr interface. Our results demonstrate that STM may be used as a tool for investigations of the semiconductor–insulator interfaces.

  4. Surface analysis with STM and AFM

    CERN Document Server

    Magonov, Sergi N

    1996-01-01

    Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) are powerful tools for surface examination. In the past, many STM and AFM studies led to erroneous conclusions due to lack of proper theoretical considerations and of an understanding of how image patterns are affected by measurement conditions. For this book, two world experts, one on theoretical analysis and the other on experimental characterization, have joined forces to bring together essential components of STM and AFM studies: The practical aspects of STM, the image simulation by surface electron density plot calculat

  5. Bulk Copper Electrodeposition on Gold Imaged by In Situ STM

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Bech-Nielsen, Gregers; Møller, Per

    1996-01-01

    Electrochemical measurements were carried out simultaneously with acquisition of in situ STM images of copper electrodeposition at low cathodic overpotentials and subsequent dissolution from the underlying polycrystalline gold surfaces. The morphologies of the copper deposits were examined...

  6. Structure analysis of ultra-thin films. STM/AFM. Chousumaku no kozo kaiseki. STM/AFM

    Energy Technology Data Exchange (ETDEWEB)

    Nozoe, H; Yumura, M [National Institute of Materials and Chemical Research, Tsukuba (Japan)

    1994-03-30

    Fullerene (C60) and carbon nanotubes are expected as new carbon structures. This article describes the observation results of C60 and carbon nanotubes by means of STM (scanning tunnel microscope). The STM images of C60 thin films are illustrated, which have been obtained by annealing at 290 centigrade. It was confirmed that C60 monomolecular thin films are formed which conform to the substrate and have high regularity. The step height of C60 monomolecular thin films coincided with the step height of Cu (111) plane, which suggested that the step of films is reflected in that of Cu substrate. For the STM images under bias voltages, various images of C60 with three-fold axis of symmetry were observed. On the other hand, from STM observation of carbon nanotubes with diameter of about 30 nm which were separated and purified from the cathode deposits during the preparation process of C60, it was found that they have concentric multilayer structure. 18 refs., 7 figs.

  7. In situ STM imaging of the structures of pentacene molecules adsorbed on Au(111).

    Science.gov (United States)

    Pong, Ifan; Yau, Shuehlin; Huang, Peng-Yi; Chen, Ming-Chou; Hu, Tarng-Shiang; Yang, Yawchia; Lee, Yuh-Lang

    2009-09-01

    In situ scanning tunneling microscope (STM) was used to examine the spatial structures of pentacene molecules adsorbed onto a Au(111) single-crystal electrode from a benzene dosing solution containing 16-400 microM pentacene. Molecular-resolution STM imaging conducted in 0.1 M HClO(4) revealed highly ordered pentacene structures of ( radical31 x radical31)R8.9 degrees , (3 x 10), ( radical31 x 10), and ( radical7 x 2 radical7)R19.1 degrees adsorbed on the reconstructed Au(111) electrode dosed with different pentacene solutions. These pentacene structures and the reconstructed Au(111) substrate were stable between 0.2 and 0.8 V [vs reversible hydrogen electrode, RHE]. Increasing the potential to E > 0.8 V lifted the reconstructed Au(111) surface and disrupted the ordered pentacene adlattices simultaneously. Ordered pentacene structures could be restored by applying potentials negative enough to reinforce the reconstructed Au(111). At potentials negative of 0.2 V, the adsorption of protons became increasingly important to displace adsorbed pentacene admolecules. Although the reconstructed Au(111) structure was not essential to produce ordered pentacene adlayers, it seemed to help the adsorption of pentacene molecules in a long-range ordered pattern. At room temperature (25 degrees C), approximately 100 pentacene molecules seen in STM images could rotate and align themselves to a neighboring domain in 10 s, suggesting that pentacene admolecules could be mobile on Au(111) under the STM imaging conditions of -150 mV in bias voltage and 1 nA in feedback current.

  8. STM Imaging of Localized Surface Plasmons on Individual Gold Nanoislands.

    Science.gov (United States)

    Nguyen, Huy A; Banerjee, Progna; Nguyen, Duc; Lyding, Joseph W; Gruebele, Martin; Jain, Prashant K

    2018-04-19

    An optically modulated scanning tunneling microscopy technique developed for measurement of single-molecule optical absorption is used here to image the light absorption by individual Au nanoislands and Au nanostructures. The technique is shown to spatially map, with nanometer resolution, localized surface plasmons (LSPs) excited within the nanoislands. Electrodynamic simulations demonstrate the correspondence of the measured images to plasmonic near-field intensity maps. The optical STM imaging technique captures the wavelength, polarization, and geometry dependence of the LSP resonances and their corresponding near-fields. Thus, we introduce a tool for real-space, nanometer-scale visualization of optical energy absorption, transport, and dissipation in complex plasmonic nanostructures.

  9. STM imaging of buried P atoms in hydrogen-terminated Si for the fabrication of a Si:P quantum computer

    Energy Technology Data Exchange (ETDEWEB)

    Oberbeck, L.; Curson, N.J.; Hallam, T.; Simmons, M.Y.; Clark, R.G

    2004-10-01

    The fabrication of atomic-scale devices in silicon requires the encapsulation of dopant atoms which have been incorporated into the silicon surface at atomically precise positions using scanning tunnelling microscopy (STM) lithography. During silicon encapsulation, it is important to minimise segregation and diffusion of dopant atoms in order to retain the lithography defined device structure. Buried dopant imaging using STM is capable of imaging dopant atoms such as phosphorus after encapsulation in silicon several monolayers below the silicon surface, thus making it possible to check the integrity of the device structure. To fabricate buried phosphorus-doped samples, we use phosphine gas as a source of phosphorus atoms and incorporate the phosphorus atoms into a Si(001) surface during an annealing step. Molecular beam epitaxy is used to encapsulate the dopant atoms with several monolayers of silicon. After encapsulation, we hydrogen terminate the silicon surface in order to image the buried phosphorus dopants using STM. We show that a buried phosphorus atom appears as a bright glow superimposed on the silicon dimer structure in empty state STM images, whereas filled state images only show a very faint protrusion in the vicinity of the phosphorus atom. We highlight the importance of our results for the fabrication of atomic-scale devices.

  10. STM imaging of buried P atoms in hydrogen-terminated Si for the fabrication of a Si:P quantum computer

    International Nuclear Information System (INIS)

    Oberbeck, L.; Curson, N.J.; Hallam, T.; Simmons, M.Y.; Clark, R.G.

    2004-01-01

    The fabrication of atomic-scale devices in silicon requires the encapsulation of dopant atoms which have been incorporated into the silicon surface at atomically precise positions using scanning tunnelling microscopy (STM) lithography. During silicon encapsulation, it is important to minimise segregation and diffusion of dopant atoms in order to retain the lithography defined device structure. Buried dopant imaging using STM is capable of imaging dopant atoms such as phosphorus after encapsulation in silicon several monolayers below the silicon surface, thus making it possible to check the integrity of the device structure. To fabricate buried phosphorus-doped samples, we use phosphine gas as a source of phosphorus atoms and incorporate the phosphorus atoms into a Si(001) surface during an annealing step. Molecular beam epitaxy is used to encapsulate the dopant atoms with several monolayers of silicon. After encapsulation, we hydrogen terminate the silicon surface in order to image the buried phosphorus dopants using STM. We show that a buried phosphorus atom appears as a bright glow superimposed on the silicon dimer structure in empty state STM images, whereas filled state images only show a very faint protrusion in the vicinity of the phosphorus atom. We highlight the importance of our results for the fabrication of atomic-scale devices

  11. Influence of the State of the Tungsten Tip on STM Topographic Images of SnSe Surfaces

    Science.gov (United States)

    Ly, Trinh Thi; Kim, Jungdae

    2018-03-01

    Tin selenide (SnSe) has recently attracted significant attention because of its excellent thermoelectric properties with a figure of merit (ZT) of 2.6. Previous scanning tunneling microscopy (STM) studies of SnSe surfaces showed that only Sn atoms are resolved in topographic images due to the dominant contribution of the Sn 5 p z states in tunneling. However, when the state of the tungsten (W) tip changes from a typical four-lobe d state such as d xy or {d_{{x^2} - {y^2}}} to a two-lobe {d_{{z^2}}} state, the atomic features observed on the SnSe surface in STM topography can be dramatically altered. In this report, we present the results of a systematic study on the influence of the W tip's states on the STM images of SnSe surfaces. Sn atoms are observed with much stronger corrugation amplitude and smaller apparent radius when the tip is in a {d_{{z^2}}} state. In addition, the atomic features of the Se atoms become visible because of the sharply focused shape of the W {d_{{z^2}}} state. We expect our results to provide important information for establishing a better understanding of the microscopic nature of SnSe surfaces.

  12. Ab initio STM and STS simulations on magnetic and nonmagnetic metallic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Dick, Alexey

    2008-04-14

    The aim of this work was to provide an in-depth understanding of a new generation of scan- ning tunneling microscopy experiments, performed employing different regimes of the STM: the spectroscopy-mode (the so-called Fourier Transformed STM, FT-STM), and the spin-sensitive mode (the so-called spin-polarized STM, SP-STM). In the present thesis ab initio tools are proposed that are based on DFT calculations to theoretically predict and analyze such types of the STM. The first part of this thesis focusses on the simulation of FT-STM, the mode that allows to probe local dispersion properties of the electrons at the surface. In order to provide the theoretical counterpart of the experimental FT-STM spectra we have introduced a new implicit approach that is derived from Tersoff-Hamann theory of the STM. The importance of an accurate description of surface wavefunctions at 5-15 A above the surface as well as the spurious quantum- size effects have been discussed in detail together with approaches to obtain converged FT-STM images. We applied our method to FT-STM experiments performed on Ag(110) surfaces. In the second part of the thesis we discuss the modeling of the spin-resolved STM, the mode that allows to characterize the magnetic structure of a surface. As a case system we studied here the magnetically-ordered transition-metal nitride surface Mn{sub 3}N{sub 2}(010). Because SP-STM experiments did not allow a conclusive understanding of the surface structure, we have first employed ab initio thermodynamics to figure out the most stable magnetic and atomic configuration of the surface that are consistent with experiments. To simulate SP-STM images on the most stable Mn{sub 3}N{sub 2}(010) surface we have employed the spin-generalized transfer-Hamiltonian formalism, assuming that the tip wavefunctions have dominant radial symmetry (s-like tip). (orig.)

  13. Application of Machine Learning tools to recognition of molecular patterns in STM images

    Science.gov (United States)

    Maksov, Artem; Ziatdinov, Maxim; Fujii, Shintaro; Kiguchi, Manabu; Higashibayashi, Shuhei; Sakurai, Hidehiro; Kalinin, Sergei; Sumpter, Bobby

    The ability to utilize individual molecules and molecular assemblies as data storage elements has motivated scientist for years, concurrent with the continuous effort to shrink a size of data storage devices in microelectronics industry. One of the critical issues in this effort lies in being able to identify individual molecular assembly units (patterns), on a large scale in an automated fashion of complete information extraction. Here we present a novel method of applying machine learning techniques for extraction of positional and rotational information from scanning tunneling microscopy (STM) images of π-bowl sumanene molecules on gold. We use Markov Random Field (MRF) model to decode the polar rotational states for each molecule in a large scale STM image of molecular film. We further develop an algorithm that uses a convolutional Neural Network combined with MRF and input from density functional theory to classify molecules into different azimuthal rotational classes. Our results demonstrate that a molecular film is partitioned into distinctive azimuthal rotational domains consisting typically of 20-30 molecules. In each domain, the ``bowl-down'' molecules are generally surrounded by six nearest neighbor molecules in ``bowl-up'' configuration, and the resultant overall structure form a periodic lattice of rotational and polar states within each domain. Research was supported by the US Department of Energy.

  14. THE INFLUENCE OF DESTINATION IMAGE AND TOURIST SATISFACTION TOWARD REVISIT INTENTION OF SETU BABAKAN BETAWI CULTURAL VILLAGE

    Directory of Open Access Journals (Sweden)

    Setyo Ferry Wibowo

    2016-04-01

    Full Text Available The purpose of this research are: 1 To find out the description of destination image, tourist satisfaction, and revisit intention of Betawi cultural village Setu Babakan, 2 test empirically the influence of destination image toward revisit intention of Betawi cultural village Setu Babakan, 3 test empirically the influence of tourist satisfaction toward revisit intention of Betawi cultural village Setu Babakan, 4 test empirically the influence of destination image toward revisit intention of Betawi cultural village Setu Babakan. The object of this research was 200 respondents who have ever visit to Betawi cultural village Setu Babakan at one time. The results of descriptive test explained that the destination image provided is good according to the tourist, so that the tourist is satisfied and want to revisit intention of Betawi cultural village Setu Babakan. The hypothesis test shows: 1 the influence of destination image toward revisit intention by -30%, 2 the influence of tourist satisfaction toward revisit intention by 118%, 3 the influence of destination image toward tourist satisfaction by 92%.

  15. THE INFLUENCE OF DESTINATION IMAGE AND TOURIST SATISFACTION TOWARD REVISIT INTENTION OF SETU BABAKAN BETAWI CULTURAL VILLAGE

    OpenAIRE

    Wibowo, Setyo Ferry; Sazali, Adnan; Kresnamurti R. P., Agung

    2016-01-01

    The purpose of this research are: 1) To find out the description of destination image, tourist satisfaction, and revisit intention of Betawi cultural village Setu Babakan, 2) test empirically the influence of destination image toward revisit intention of Betawi cultural village Setu Babakan, 3) test empirically the influence of tourist satisfaction toward revisit intention of Betawi cultural village Setu Babakan, 4) test empirically the influence of destination image toward revisit intention ...

  16. Scanning tunneling microscopy III theory of STM and related scanning probe methods

    CERN Document Server

    Güntherodt, Hans-Joachim

    1993-01-01

    While the first two volumes on Scanning Tunneling Microscopy (STM) and its related scanning probe (SXM) methods have mainly concentrated on intro­ ducing the experimental techniques, as well as their various applications in different research fields, this third volume is exclusively devoted to the theory of STM and related SXM methods. As the experimental techniques including the reproducibility of the experimental results have advanced, more and more theorists have become attracted to focus on issues related to STM and SXM. The increasing effort in the development of theoretical concepts for STM/SXM has led to considerable improvements in understanding the contrast mechanism as well as the experimental conditions necessary to obtain reliable data. Therefore, this third volume on STM/SXM is not written by theorists for theorists, but rather for every scientist who is not satisfied by just obtaining real­ space images of surface structures by STM/SXM. After a brief introduction (Chap. 1), N. D. Lang first co...

  17. Haptic-STM: a human-in-the-loop interface to a scanning tunneling microscope.

    Science.gov (United States)

    Perdigão, Luís M A; Saywell, Alex

    2011-07-01

    The operation of a haptic device interfaced with a scanning tunneling microscope (STM) is presented here. The user moves the STM tip in three dimensions by means of a stylus attached to the haptic instrument. The tunneling current measured by the STM is converted to a vertical force, applied to the stylus and felt by the user, with the user being incorporated into the feedback loop that controls the tip-surface distance. A haptic-STM interface of this nature allows the user to feel atomic features on the surface and facilitates the tactile manipulation of the adsorbate/substrate system. The operation of this device is demonstrated via the room temperature STM imaging of C(60) molecules adsorbed on an Au(111) surface in ultra-high vacuum.

  18. Electronic structure, total energies, and STM images of clean and oxygen-covered Al(111)

    DEFF Research Database (Denmark)

    Jacobsen, Joachim; Hammer, Bjørk; Jacobsen, Karsten Wedel

    1995-01-01

    an attractive O-O interaction is identified together with an enhancement in the dipole moment induced per O atom. Finally, Tersoff-Hamann-type scanning tunneling microscopy (STM) topographs are derived based on the calculated one-electron wave functions and spectra. For the clean Al(111) a theoretical STM...

  19. Cryogenic STM in 3D vector magnetic fields realized through a rotatable insert.

    Science.gov (United States)

    Trainer, C; Yim, C M; McLaren, M; Wahl, P

    2017-09-01

    Spin-polarized scanning tunneling microscopy (SP-STM) performed in vector magnetic fields promises atomic scale imaging of magnetic structure, providing complete information on the local spin texture of a sample in three dimensions. Here, we have designed and constructed a turntable system for a low temperature STM which in combination with a 2D vector magnet provides magnetic fields of up to 5 T in any direction relative to the tip-sample geometry. This enables STM imaging and spectroscopy to be performed at the same atomic-scale location and field-of-view on the sample, and most importantly, without experiencing any change on the tip apex before and after field switching. Combined with a ferromagnetic tip, this enables us to study the magnetization of complex magnetic orders in all three spatial directions.

  20. ECT DAMAGE INDICATES STM DIVIDED INTO STM CONTROL & LTM TRACES: NEUROLOGICAL DEFINITION OF “CONFUSION”

    Directory of Open Access Journals (Sweden)

    Eugen Tarnow

    2017-12-01

    Full Text Available Recently it was shown that short term memory (STM free recall consists of two stages: the first few recalls empty working memory and a second stage, a reactivation stage, concludes the recall (Tarnow, 2015; for a review of the theoretical predictions see Murdock, 1974. Bayley et al (2000 investigated free recall in people who had undergone Electroconvulsive therapy (ECT and found that both recency and primacy effects were normal. Here I investigate this further, and argue that this finding suggests a division of STM between STM Control and long term memory (LTM traces and that STM Control is not effected by ECT.Serial position probabilities from an investigation of Bayley et al (2000 were used to compare 11 subjects with ECT treatments to a control group and to a group of Alzheimer’s subjects.The free recall probabilities are found to be separable into the serial position curves and the overall probability of recall. This suggests that STM is separable into an STM Control structure (the serial position curve responsible for working memory and reactivation functions and LTM traces (the overall probability of recall.Using the ECT review of Abbott et al (2014a showing excess activity in MTL and lacking activity in the frontal lobes I suggest that STM Control is overworked trying to establish stable patterns in LTM. It could be that the confusion resulting from ECT is due to the failure of this process, suggesting a neurological definition of confusion.

  1. SSE software test management STM capability: Using STM in the Ground Systems Development Environment (GSDE)

    Science.gov (United States)

    Church, Victor E.; Long, D.; Hartenstein, Ray; Perez-Davila, Alfredo

    1992-01-01

    This report is one of a series discussing configuration management (CM) topics for Space Station ground systems software development. It provides a description of the Software Support Environment (SSE)-developed Software Test Management (STM) capability, and discusses the possible use of this capability for management of developed software during testing performed on target platforms. This is intended to supplement the formal documentation of STM provided by the SEE Project. How STM can be used to integrate contractor CM and formal CM for software before delivery to operations is described. STM provides a level of control that is flexible enough to support integration and debugging, but sufficiently rigorous to insure the integrity of the testing process.

  2. Examining Relationships of Destination Image, Service Quality, e-WOM, and Revisit Intention to Sabang Island, Indonesia

    Directory of Open Access Journals (Sweden)

    Rangga Restu Prayogo

    2016-12-01

    Full Text Available The purpose of this research is to study the relationship among destination image, service quality, e-WOM, and revisit intentions in the tourism industry. A questionnaire given to tourists who visit one of the farrest island in western part of Indonesia, Sabang Island and using sampling through the convenience sampling. A structural equation model (SEM test with WarpPLS 3.0 was used to test the relationship between research variables. This research gathered from 150 respondents. The empirical results from PLS-SEM showed that; the destination image positive affect e-WOM and revisit intention; service quality affect e-WOM and revisit intention; e-WOM positive affect to revisit intention tourists. The implications and future research issues were discussed.

  3. STM-SQUID probe microscope

    International Nuclear Information System (INIS)

    Hayashi, Tadayuki; Tachiki, Minoru; Itozaki, Hideo

    2007-01-01

    We have developed a STM-SQUID probe microscope. A high T C SQUID probe microscope was combined with a scanning tunneling microscope for investigation of samples at room temperature in air. A high permeability probe needle was used as a magnetic flux guide to improve the spatial resolution. The probe with tip radius of less than 100 nm was prepared by microelectropolishing. The probe was also used as a scanning tunneling microscope tip. Topography of the sample surface could be measured by the scanning tunneling microscope with high spatial resolution prior to observation by SQUID microscopy. The SQUID probe microscope image could be observed while keeping the distance from the sample surface to the probe tip constant. We observed a topographic image and a magnetic image of Ni fine pattern and also a magnetically recorded hard disk. Furthermore we have investigated a sample vibration method of the static magnetic field emanating from a sample with the aim of achieving a higher signal-to-noise (S/N) ratio

  4. Mechanism of high-resolution STM/AFM imaging with functionalized tips

    Czech Academy of Sciences Publication Activity Database

    Hapala, Prokop; Kichin, G.; Wagner, C.; Tautz, F.S.; Temirov, R.; Jelínek, Pavel

    2014-01-01

    Roč. 90, č. 8 (2014), "085421-1"-"085421-9" ISSN 1098-0121 R&D Projects: GA ČR(CZ) GC14-16963J Grant - others:AVČR(CZ) M100101207 Institutional support: RVO:68378271 Keywords : AFM * STM * high resolution Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  5. STM, SECPM, AFM and Electrochemistry on Single Crystalline Surfaces

    Directory of Open Access Journals (Sweden)

    Ulrich Stimming

    2010-08-01

    Full Text Available Scanning probe microscopy (SPM techniques have had a great impact on research fields of surface science and nanotechnology during the last decades. They are used to investigate surfaces with scanning ranges between several 100 mm down to atomic resolution. Depending on experimental conditions, and the interaction forces between probe and sample, different SPM techniques allow mapping of different surface properties. In this work, scanning tunneling microscopy (STM in air and under electrochemical conditions (EC-STM, atomic force microscopy (AFM in air and scanning electrochemical potential microscopy (SECPM under electrochemical conditions, were used to study different single crystalline surfaces in electrochemistry. Especially SECPM offers potentially new insights into the solid-liquid interface by providing the possibility to image the potential distribution of the surface, with a resolution that is comparable to STM. In electrocatalysis, nanostructured catalysts supported on different electrode materials often show behavior different from their bulk electrodes. This was experimentally and theoretically shown for several combinations and recently on Pt on Au(111 towards fuel cell relevant reactions. For these investigations single crystals often provide accurate and well defined reference and support systems. We will show heteroepitaxially grown Ru, Ir and Rh single crystalline surface films and bulk Au single crystals with different orientations under electrochemical conditions. Image studies from all three different SPM methods will be presented and compared to electrochemical data obtained by cyclic voltammetry in acidic media. The quality of the single crystalline supports will be verified by the SPM images and the cyclic voltammograms. Furthermore, an outlook will be presented on how such supports can be used in electrocatalytic studies.

  6. The ReactorSTM: Atomically resolved scanning tunneling microscopy under high-pressure, high-temperature catalytic reaction conditions

    Energy Technology Data Exchange (ETDEWEB)

    Herbschleb, C. T.; Tuijn, P. C. van der; Roobol, S. B.; Navarro, V.; Bakker, J. W.; Liu, Q.; Stoltz, D.; Cañas-Ventura, M. E.; Verdoes, G.; Spronsen, M. A. van; Bergman, M.; Crama, L.; Taminiau, I.; Frenken, J. W. M., E-mail: frenken@physics.leidenuniv.nl [Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. box 9504, 2300 RA Leiden (Netherlands); Ofitserov, A.; Baarle, G. J. C. van [Leiden Probe Microscopy B.V., J.H. Oortweg 21, 2333 CH Leiden (Netherlands)

    2014-08-15

    To enable atomic-scale observations of model catalysts under conditions approaching those used by the chemical industry, we have developed a second generation, high-pressure, high-temperature scanning tunneling microscope (STM): the ReactorSTM. It consists of a compact STM scanner, of which the tip extends into a 0.5 ml reactor flow-cell, that is housed in a ultra-high vacuum (UHV) system. The STM can be operated from UHV to 6 bars and from room temperature up to 600 K. A gas mixing and analysis system optimized for fast response times allows us to directly correlate the surface structure observed by STM with reactivity measurements from a mass spectrometer. The in situ STM experiments can be combined with ex situ UHV sample preparation and analysis techniques, including ion bombardment, thin film deposition, low-energy electron diffraction and x-ray photoelectron spectroscopy. The performance of the instrument is demonstrated by atomically resolved images of Au(111) and atom-row resolution on Pt(110), both under high-pressure and high-temperature conditions.

  7. Structural characterization and comparison of iridium, platinum and gold/palladium ultra-thin film coatings for STM of biomolecules

    Energy Technology Data Exchange (ETDEWEB)

    Sebring, R.; Arendt, P.; Imai, B.; Bradbury, E.M.; Gatewood, J. [Los Alamos National Lab., NM (United States); Panitz, J. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Physics and Astronomy; Yau, P. [Univ. of California, Davis, CA (United States)

    1997-10-30

    Scanning tunneling microscopy (STM) is capable of atomic resolution and is ideally suited for imaging surfaces with uniform work function. A biological sample on a conducting substrate in air does not meet this criteria and requires a conductive coating for stable and reproducible STM imaging. In this paper, the authors describe the STM and transmission electron microscopy (TEM) characterization of ultra-thin ion-beam sputtered films of iridium and cathode sputtered gold/palladium and platinum films on highly ordered pyrolytic graphite (HOPG) which were developed for use as biomolecule coatings. The goals were the development of metal coatings sufficiently thin and fine grained that 15--20 {angstrom} features of biological molecules could be resolved using STM, and the development of a substrate/coating system which would allow complementary TEM information to be obtained for films and biological molecules. The authors demonstrate in this paper that ion-beam sputtered iridium on highly ordered pyrolytic graphite (HOPG) has met both these goals. The ion-beam sputtered iridium produced a very fine grained (< 10 {angstrom}) continuous film at 5--6 {angstrom} thickness suitable for stable air STM imaging. In comparison, cathode sputtered platinum produced 16 {angstrom} grains with the thinnest continuous film at 15 {angstrom} thickness, and the sputtered gold/palladium produced 25 {angstrom} grains with the thinnest continuous film at 18 {angstrom} thickness.

  8. Electronic structure of the cuprate superconducting and pseudogap phases from spectroscopic imaging STM

    Science.gov (United States)

    Schmidt, A. R.; Fujita, K.; Kim, E.-A.; Lawler, M. J.; Eisaki, H.; Uchida, S.; Lee, D.-H.; Davis, J. C.

    2011-06-01

    We survey the use of spectroscopic imaging scanning tunneling microscopy (SI-STM) to probe the electronic structure of underdoped cuprates. Two distinct classes of electronic states are observed in both the d-wave superconducting (dSC) and the pseudogap (PG) phases. The first class consists of the dispersive Bogoliubov quasiparticle excitations of a homogeneous d-wave superconductor, existing below a lower energy scale E=Δ0. We find that the Bogoliubov quasiparticle interference (QPI) signatures of delocalized Cooper pairing are restricted to a k-space arc, which terminates near the lines connecting k=±(π/a0,0) to k=±(0,π/a0). This arc shrinks continuously with decreasing hole density such that Luttinger's theorem could be satisfied if it represents the front side of a hole-pocket that is bounded behind by the lines between k=±(π/a0,0) and k=±(0,π/a0). In both phases, the only broken symmetries detected for the |E|modulations, locally breaking both rotational and translational symmetries, coexist with this intra-unit-cell electronic symmetry breaking at E=Δ1. Their characteristic wavevector Q is determined by the k-space points where Bogoliubov QPI terminates and therefore changes continuously with doping. The distinct broken electronic symmetry states (intra-unit-cell and finite Q) coexisting at E~Δ1 are found to be indistinguishable in the dSC and PG phases. The next challenge for SI-STM studies is to determine the relationship of the E~Δ1 broken symmetry electronic states with the PG phase, and with the E<Δ0 states associated with Cooper pairing.

  9. STM contrast inversion of the Fe(1 1 0) surface

    Energy Technology Data Exchange (ETDEWEB)

    Mándi, Gábor [Budapest University of Technology and Economics, Department of Theoretical Physics, Budafoki út 8, H-1111 Budapest (Hungary); Palotás, Krisztián, E-mail: palotas@phy.bme.hu [Budapest University of Technology and Economics, Department of Theoretical Physics, Budafoki út 8, H-1111 Budapest (Hungary); Condensed Matter Research Group of the Hungarian Academy of Sciences, Budafoki út 8, H-1111 Budapest (Hungary)

    2014-06-01

    We extend the orbital-dependent electron tunneling model implemented within the three-dimensional (3D) Wentzel–Kramers–Brillouin (WKB) atom-superposition approach to simulate spin-polarized scanning tunneling microscopy (SP-STM) above magnetic surfaces. The tunneling model is based on the electronic structure data of the magnetic tip and surface obtained from first principles. Applying our method, we analyze the orbital contributions to the tunneling current, and study the nature of atomic contrast reversals occurring on constant-current SP-STM images above the Fe(1 1 0) surface. We find an interplay of orbital-dependent tunneling and spin-polarization effects responsible for the contrast inversion, and we discuss its dependence on the bias voltage, on the tip-sample distance, and on the tip orbital composition.

  10. Defects of SiC nanowires studied by STM and STS

    International Nuclear Information System (INIS)

    Busiakiewicz, A.; Huczko, A.; Dudziak, T.; Puchalski, M.; Kozlowski, W.; Cichomski, M.; Cudzilo, S.; Klusek, Z.; Olejniczak, W.

    2010-01-01

    For the first time the scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) are employed to investigate the morphology and the surface electronic structure of the defective silicon carbide nanowires (SiCNWs). The SiCNWs produced via combustion synthesis route are studied. The STS measurements are performed in the current imaging tunneling spectroscopy mode (CITS) that allows us to determine the correlation between STM topography and the local density of electronic states (LDOS) around the bend of an isolated SiCNW. The measurements reveal fluctuations of LDOS in the vicinity of the defect. The local graphitisation and the inhomogeneous concentration of doping impurities (e.g. nitrogen, oxygen) are considered to explain these fluctuations of metallic-like LDOS in the vicinity of the SiCNW's deformation.

  11. Functionalized molecules studied by STM: motion, switching and reactivity

    International Nuclear Information System (INIS)

    Grill, Leonhard

    2008-01-01

    Functionalized molecules represent the central issue of molecular nanotechnology. Scanning tunnelling microscopy (STM) is a powerful method to investigate such molecules, because it allows us to image them with sub-molecular resolution when adsorbed on a surface and can be used at the same time as a tool to manipulate single molecules in a controlled way. Such studies permit deep insight into the conformational, mechanical and electronic structure and thus functionalities of the molecules. In this review, recent experiments on specially designed molecules, acting as model systems for molecular nanotechnology, are reviewed. The presented studies focus on key functionalities: lateral rolling and hopping motion on a supporting surface, the switching behaviour of azobenzene derivatives by using the STM tip and the controlled reactivity of molecular side groups, which enable the formation of covalently bound molecular nanoarchitectures. (topical review)

  12. Transistor effects and in situ STM of redox molecules at room temperature

    DEFF Research Database (Denmark)

    Albrecht, Tim; Guckian, A; Vos, JG

    2005-01-01

    . It predicts a distinct increase of the tunnelling current close to the equilibrium potential, i.e., if molecular bridge states are tuned into resonance with the Fermi levels of the enclosing electrodes. The complexes display robust electrochemistry on Au(111) electrode surfaces. STM images at molecular......Inorganic transition metal complexes were identified as potential candidates for transistor-like behavior in an electrochemical scanning tunnelling microscope (STM) configuration at room temperature. The theoretical background has been established based on condensed matter charge transfer theory...... resolution reveal detailed information on their surface structure and scanning tunnelling spectroscopy experiments have shown clear evidence of transistor-like behavior...

  13. A compact combined ultrahigh vacuum scanning tunnelling microscope (UHV STM) and near-field optical microscope

    International Nuclear Information System (INIS)

    Woolley, R A J; Hayton, J A; Cavill, S; Ma, Jin; Beton, P H; Moriarty, P

    2008-01-01

    We have designed and constructed a hybrid scanning near-field optical microscope (SNOM)–scanning tunnelling microscope (STM) instrument which operates under ultrahigh vacuum (UHV) conditions. Indium tin oxide (ITO)-coated fibre-optic tips capable of high quality STM imaging and tunnelling spectroscopy are fabricated using a simple and reliable method which foregoes the electroless plating strategy previously employed by other groups. The fabrication process is reproducible, producing robust tips which may be exchanged under UHV conditions. We show that controlled contact with metal surfaces considerably enhances the STM imaging capabilities of fibre-optic tips. Light collection (from the cleaved back face of the ITO-coated fibre-optic tip) and optical alignment are facilitated by a simple two-lens arrangement where the in-vacuum collimation/collection lens may be adjusted using a slip-stick motor. A second in-air lens focuses the light (which emerges from the UHV system as a parallel beam) onto a cooled CCD spectrograph or photomultiplier tube. The application of the instrument to combined optical and electronic spectroscopy of Au and GaAs surfaces is discussed

  14. Revisitation: a trans phenomenology of the media image

    Directory of Open Access Journals (Sweden)

    Cael M Keegan

    2016-12-01

    Full Text Available How might certain moving images move us into transgender becoming? The recent proliferation of transgender images in the media of the Global North has been widely regarded as supporting transgender political and social equality. But do these images do justice to the complexity of transgender lives? Who are images of transgender identity made for, and whose interests do they serve? Instead of discussing media that produce a transgender object for public consumption, this essay’s author is interested in theorizing a trans point of media reception for the popular image. This essay illustrates how transgender subjects might fashion their own archives of becoming through encounters with media that unintentionally support transgender embodiment as a possibility in the world. Revisiting his phenomenological encounters with the film Under the Skin and the “Milk: It Does a Body Good” ad campaign, the author analyzes how certain media objects have the unexpected power to “move” the transgender subject into becoming.

  15. Restructuring STM (Science, Technology, and Mathematics) Education for Entrepreneurship

    Science.gov (United States)

    Ezeudu, F. O.; Ofoegbu, T. O.; Anyaegbunnam, N. J.

    2013-01-01

    This paper discussed the need to restructure STM (science, technology, and mathematics) education to reflect entrepreneurship. This is because the present STM education has not achieved its aim of making graduates self-reliant. Entrepreneurship education if introduced in the STM education will produce graduate who can effectively manage their…

  16. Fabrication and Characterization of CNT-Based Smart Tips for Synchrotron Assisted STM

    Directory of Open Access Journals (Sweden)

    Hui Yan

    2015-01-01

    Full Text Available Determination of chemical composition along with imaging at the atomic level provides critical information towards fundamental understanding of the surface of materials and, hence, yields the capability to design new materials by tailoring their ultimate functionalities. Synchrotron X-ray assisted scanning tunneling microscopy (SX-STM is a promising new technique to achieve real space chemically specific atomic mapping. Chemical sensitivity of SX-STM relies on excitation of core electrons by incident X-rays when their energy is tuned to an absorption edge of a particular element. However, along with core-level electrons, photoelectrons are also excited, which yield additional current and interfere with the tunneling current. To reduce the background photoelectron current and to improve ultimate resolution of SX-STM, we have developed and fabricated multiwalled carbon nanotubes (MWCNT based “smart tips” using plasma enhanced chemical vapor deposition and focused ion beam milling. The newly developed CNT-based smart tips, characterized step by step by scanning electron microscopy (SEM during the fabrication process, demonstrate good performance and provide opportunity for realizing atomic chemical mapping.

  17. Growth and structure of Si and Ge in vanadium oxide nanomesh on Pd(1 1 1) studied by STM and DFT

    International Nuclear Information System (INIS)

    Chan, Lap Hong; Hayazaki, Shinji; Ogawa, Kokushi; Yuhara, Junji

    2013-01-01

    Highlights: ► We studied the growth and structure of Si and Ge in vanadium oxide nanomesh on Pd(1 1 1) by STM and DFT calculations. ► All the Si atoms formed isolated Si nanoclusters. ► Some Ge atoms formed monomer Ge nanodots on Pd(1 1 1), while the others formed isolated Ge nanoclusters. - Abstract: The growth of silicon (Si)/germanium (Ge) atoms in a well ordered (4 × 4) vanadium (V) oxide nanomesh on Pd(1 1 1) prepared by ultra-high-vacuum evaporation has been studied by scanning tunneling microscopy (STM) and ab initio density functional theory (DFT) calculations. At the very beginning of the Si deposition, all of the Si atoms deposited were adsorbed on top of the V-oxide nanomesh, forming Si nanoclusters, and each Si atom formed was isolated other Si atoms. Two different adsorption sites for Si atoms were observed by STM. In the case of Ge deposition, some Ge atoms filled the vanadium oxide nanoholes, forming Ge nanodots on Pd(1 1 1), while the others were adsorbed on top of the V-oxide nanomesh, forming isolated Ge nanoclusters. The ab initio DFT total-energy calculations indicated that the Ge atoms occupying the nanohole were more stable than those adsorbed on the nanomesh. The simulated images were highly consistent with the experimental STM images with the exception of the Ge nanodots, which exhibited a large, uniform protrusion in the STM images. Therefore, the adsorbed atom might be mobile in the nanohole at room temperature, possibly as a result of interaction with the STM tip.

  18. STM-excited luminescence of porous and spark-processed silicon

    International Nuclear Information System (INIS)

    Andrienko, I.; Kuznetsov, V.; Yuan, J.; Haneman, D.

    1998-01-01

    Full text: Scanning tunneling microscopy (STM) permits highly local electronic excitation of light emission (LE) from the surface of silicon. Measuring STM LE, one can study simultaneously both the topography and the luminescence properties of areas down to nm dimensions and thus make conclusions about the luminescence mechanism of the material. We have built an STM spectroscopy system which allows measurement of spectra of visible light emitted from areas as small as 13 x 13 nm 2 (porous silicon) and 10 x 10 nm 2 (spark-processed silicon). Porous silicon shows a broad emission band centered at 630 nm, and spark-processed silicon, one at 690 nm. The STM LE spectra of spark-processed silicon obtained for the first time. We have found that visible light is emitted only from areas containing nanometer-scale structures down to around 2 nm in diameter. STM LE occurs under negative bias voltage applied to the tip, i.e. when electrons are injected into the sample. Other workers used p-type silicon for the sample preparations, but it has been found that STM LE can be induced also from n-type silicon. Furthermore, we have shown that STM LE spectra can be resolved using much lover voltages and tunneling currents: -(7-9) V and 25 - 50 nA vs -(25-50) V and 100 nA. To consider different excitation mechanisms, the STM LE measurements are compared with photoluminescence and electroluminescence spectra of similar samples. We suggest that excitation of individual quantum confinement structures has been observed

  19. Scanning tunneling microscopy - STM: history, principle, construction, and related techniques

    International Nuclear Information System (INIS)

    Ostadal, I.; Sobotik, P.

    1998-01-01

    The method of scanning tunneling microscopy (STM) is discussed. The principle of STM and some other related methods is highlighted, and spectroscopy using STM is dealt with. A brief summary is given of problems to be solved in microscope design, and the influence of these on the resolution obtained is presented. A comparison of STM with other methods used at present in the physics of thin films and surfaces confirms its irreplaceability

  20. Oxygen adsorption on the Al9Co2(001) surface: first-principles and STM study

    International Nuclear Information System (INIS)

    Villaseca, S Alarcón; Loli, L N Serkovic; Ledieu, J; Fournée, V; Dubois, J-M; Gaudry, É; Gille, P

    2013-01-01

    Atomic oxygen adsorption on a pure aluminum terminated Al 9 Co 2 (001) surface is studied by first-principle calculations coupled with STM measurements. Relative adsorption energies of oxygen atoms have been calculated on different surface sites along with the associated STM images. The local electronic structure of the most favourable adsorption site is described. The preferential adsorption site is identified as a ‘bridge’ type site between the cluster entities exposed at the (001) surface termination. The Al–O bonding between the adsorbate and the substrate presents a covalent character, with s–p hybridization occurring between the states of the adsorbed oxygen atom and the aluminum atoms of the surface. The simulated STM image of the preferential adsorption site is in agreement with experimental observations. This work shows that oxygen adsorption generates important atomic relaxations of the topmost surface layer and that sub-surface cobalt atoms strongly influence the values of the adsorption energies. The calculated Al–O distances are in agreement with those reported in Al 2 O and Al 2 O 3 oxides and for oxygen adsorption on Al(111). (paper)

  1. Design and performance of an in situ high vacuum STM in beam line at 15 UD pelletron accelerator

    International Nuclear Information System (INIS)

    Singh, J.P.; Tripathi, A.; Ahuja, R.; Dutt, R.N.; Kanjilal, D.; Mehta, G.K.; Raychoudhuri, A.K.

    2000-01-01

    The design, installation and performance of an in situ high vacuum STM in the materials science beam line of 15 UD tandem Pelletron accelerator, NSC are reported. The scanning tunneling microscope (STM) has imaged highly oriented pyrolytic graphite (HOPG) surfaces with atomic resolution. Local current-voltage spectroscopy has also been performed on p-type Si (111) samples. A band gap of 1.09 ± 0.1 eV was calculated. (author)

  2. Using Ab-Initio Calculations to Appraise Stm-Based - and Kink-Formation Energies

    Science.gov (United States)

    Feibelman, Peter J.

    2001-03-01

    Ab-initio total energies can and should be used to test the typically model-dependent results of interpreting STM morphologies. The benefits of such tests are illustrated here by ab-initio energies of step- and kink-formation on Pb and Pt(111) which show that the STM-based values of the kink energies must be revised. On Pt(111), the computed kink-energies for (100)- and (111)-microfacet steps are about 0.25 and 0.18 eV. These results imply a specific ratio of formation energies for the two step types, namely 1.14, in excellent agreement with experiment. If kink-formation actually cost the same energy on the two step types, an inference drawn from scanning probe observations of step wandering,(M. Giesen et al., Surf. Sci. 366, 229(1996).) this ratio ought to be 1. In the case of Pb(111), though computed energies to form (100)- and (111)-microfacet steps agree with measurement, the ab-initio kink-formation energies for the two step types, 41 and 60 meV, are 40-50% below experimental values drawn from STM images.(K. Arenhold et al., Surf. Sci. 424, 271(1999).) The discrepancy results from interpreting the images with a step-stiffness vs. kink-energy relation appropriate to (100) but not (111) surfaces. Good agreement is found when proper account of the trigonal symmetry of Pb(111) is taken in reinterpreting the step-stiffness data.

  3. STM/STS measurements of the layered superconductor β-HfNCl1-x

    International Nuclear Information System (INIS)

    Ekino, Toshikazu; Sugimoto, Akira; Shohara, Kazuhiro; Yamanaka, Shoji; Gabovich, Alexander M.

    2010-01-01

    Scanning tunneling microcopy/spectroscopy (STM/STS) measurements have been carried out on SmSI (β) type HfNCl 1-x (x∼0.3) samples with T c =24K. The STM image on the cleaved surface of ab plane at 5 K clearly reveals a triangular arrangement of bright spots. The separation of the nearest-neighbor spots, 0.369 nm, is in agreement with the a lattice parameter. The STS measurements at 5 K reveal almost constant gap values 2Δ=20meV within the area of at least 10x10nm 2 , thus demonstrating a huge ratio 2Δ/k B T c =10. This ratio is very similar to that found in high-T c oxide and organic superconductors.

  4. Direct, coherent and incoherent intermediate state tunneling and scanning tunnel microscopy (STM)

    International Nuclear Information System (INIS)

    Halbritter, J.

    1997-01-01

    Theory and experiment in tunneling are still qualitative in nature, which hold true also for the latest developments in direct-, resonant-, coherent- and incoherent-tunneling. Those tunnel processes have recently branched out of the field of ''solid state tunnel junctions'' into the fields of scanning tunnel microscopy (STM), single electron tunneling (SET) and semiconducting resonant tunnel structures (RTS). All these fields have promoted the understanding of tunneling in different ways reaching from the effect of coherence, of incoherence and of charging in tunneling, to spin flip or inelastic effects. STM allows not only the accurate measurements of the tunnel current and its voltage dependence but, more importantly, the easy quantification via the (quantum) tunnel channel conductance and the distance dependence. This new degree of freedom entering exponentially the tunnel current allows an unique identification of individual tunnel channels and their quantification. In STM measurements large tunnel currents are observed for large distances d > 1 nm explainable by intermediate state tunneling. Direct tunneling with its reduced tunnel time and reduced off-site Coulomb charging bridges distances below 1 nm, only. The effective charge transfer process with its larger off-site and on-site charging at intermediate states dominates tunnel transfer in STM, biology and chemistry over distances in the nm-range. Intermediates state tunneling becomes variable range hopping conduction for distances larger than d > 2 nm, for larger densities of intermediate states n 1 (ε) and for larger temperatures T or voltages U, still allowing high resolution imaging

  5. Fingerprints of single nuclear spin energy levels using STM - ENDOR.

    Science.gov (United States)

    Manassen, Yishay; Averbukh, Michael; Jbara, Moamen; Siebenhofer, Bernhard; Shnirman, Alexander; Horovitz, Baruch

    2018-04-01

    We performed STM-ENDOR experiments where the intensity of one of the hyperfine components detected in ESR-STM is recorded while an rf power is irradiated into the tunneling junction and its frequency is swept. When the latter frequency is near a nuclear transition a dip in ESR-STM signal is observed. This experiment was performed in three different systems: near surface SiC vacancies where the electron spin is coupled to a next nearest neighbor 29 Si nucleus; Cu deposited on Si(111)7x7 surface, where the unpaired electron of the Cu atom is coupled to the Cu nucleus ( 63 Cu, 65 Cu) and on Tempo molecules adsorbed on Au(111), where the unpaired electron is coupled to a Nitrogen nucleus ( 14 N). While some of the hyperfine values are unresolved in the ESR-STM data due to linewidth we find that they are accurately determined in the STM-ENDOR data including those from remote nuclei, which are not detected in the ESR-STM spectrum. Furthermore, STM-ENDOR can measure single nuclear Zeeman frequencies, distinguish between isotopes through their different nuclear magnetic moments and detect quadrupole spectra. We also develop and solve a Bloch type equation for the coupled electron-nuclear system that facilitates interpretation of the data. The improved spectral resolution of STM - ENDOR opens many possibilities for nanometric scale chemical analysis. Copyright © 2018 Elsevier Inc. All rights reserved.

  6. Type-specific proactive interference in patients with semantic and phonological STM deficits.

    Science.gov (United States)

    Harris, Lara; Olson, Andrew; Humphreys, Glyn

    2014-01-01

    Prior neuropsychological evidence suggests that semantic and phonological components of short-term memory (STM) are functionally and neurologically distinct. The current paper examines proactive interference (PI) from semantic and phonological information in two STM-impaired patients, DS (semantic STM deficit) and AK (phonological STM deficit). In Experiment 1 probe recognition tasks with open and closed sets of stimuli were used. Phonological PI was assessed using nonword items, and semantic and phonological PI was assessed using words. In Experiment 2 phonological and semantic PI was elicited by an item recognition probe test with stimuli that bore phonological and semantic relations to the probes. The data suggested heightened phonological PI for the semantic STM patient, and exaggerated effects of semantic PI in the phonological STM case. The findings are consistent with an account of extremely rapid decay of activated type-specific representations in cases of severely impaired phonological and semantic STM.

  7. Strong correlation effects in theoretical STM studies of magnetic adatoms

    Science.gov (United States)

    Dang, Hung T.; dos Santos Dias, Manuel; Liebsch, Ansgar; Lounis, Samir

    2016-03-01

    We present a theoretical study for the scanning tunneling microscopy (STM) spectra of surface-supported magnetic nanostructures, incorporating strong correlation effects. As concrete examples, we study Co and Mn adatoms on the Cu(111) surface, which are expected to represent the opposite limits of Kondo physics and local moment behavior, using a combination of density functional theory and both quantum Monte Carlo and exact diagonalization impurity solvers. We examine in detail the effects of temperature T , correlation strength U , and impurity d electron occupancy Nd on the local density of states. We also study the effective coherence energy scale, i.e., the Kondo temperature TK, which can be extracted from the STM spectra. Theoretical STM spectra are computed as a function of STM tip position relative to each adatom. Because of the multiorbital nature of the adatoms, the STM spectra are shown to consist of a complicated superposition of orbital contributions, with different orbital symmetries, self-energies, and Kondo temperatures. For a Mn adatom, which is close to half-filling, the STM spectra are featureless near the Fermi level. On the other hand, the quasiparticle peak for a Co adatom gives rise to strongly position-dependent Fano line shapes.

  8. Using destination image to predict visitors' intention to revisit three Hudson River Valley, New York, communities

    Science.gov (United States)

    Rudy M. Schuster; Laura Sullivan; Duarte Morais; Diane Kuehn

    2009-01-01

    This analysis explores the differences in Affective and Cognitive Destination Image among three Hudson River Valley (New York) tourism communities. Multiple regressions were used with six dimensions of visitors' images to predict future intention to revisit. Two of the three regression models were significant. The only significantly contributing independent...

  9. Principles and simulations of high-resolution STM imaging with a flexible tip apex

    Czech Academy of Sciences Publication Activity Database

    Krejčí, Ondřej; Hapala, Prokop; Ondráček, Martin; Jelínek, Pavel

    2017-01-01

    Roč. 95, č. 4 (2017), 1-9, č. článku 045407. ISSN 2469-9950 R&D Projects: GA ČR(CZ) GC14-16963J Institutional support: RVO:68378271 Keywords : STM * AFM * high-resolution Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.836, year: 2016

  10. The STM program at TRW

    International Nuclear Information System (INIS)

    Lazar, N.H.; Barter, J.; Boehmer, H.

    1984-01-01

    The objective of the STM is to evaluate the feasibility of confining a plasma stably in a symmetric mirror configuration by taking advantage of the use of diamagnetic plasma rings as in EBT to produce an MHD stable configuration. Experiments using both ECRH and ICRH in a five-cell, symmetric tandem-mirror facility STM are described. Streaming plasmas are produced, cw, in the end cells. Multiple frequency heating at electron cyclotron resonance efficiently generate the stabilizing ''ELMO'' rings. Ion cyclotron heating of ions in the stream results in ion energies in excess of 300eV with an energetic tail extending past 3keV. Monte Carlo simulations of the heating processes will be described. (author). 3 refs, 6 figs

  11. Computational models for interpretation of wave function imaging in cross-sectional STM of quantum dots

    NARCIS (Netherlands)

    Maksym, P.A.; Roy, M.; Wijnheijmer, A.P.; Koenraad, P.M.

    2008-01-01

    Computational models are used to investigate the role of electron-electron interactions in cross-sectional STM of cleaved quantum dots. If correlation effects are weak, the tunnelling current reflects the nodal structure of the non-interacting dot states. If correlation is strong, peaks in the

  12. Atomic resolution images of graphite in air

    Energy Technology Data Exchange (ETDEWEB)

    Grigg, D.A.; Shedd, G.M.; Griffis, D.; Russell, P.E.

    1988-12-01

    One sample used for proof of operation for atomic resolution in STM is highly oriented pyrolytic graphite (HOPG). This sample has been imaged with many different STM`s obtaining similar results. Atomic resolution images of HOPG have now been obtained using an STM designed and built at the Precision Engineering Center. This paper discusses the theoretical predictions and experimental results obtained in imaging of HOPG.

  13. Measurement of chirality of charge-density-waves in TiSe2 by using STM

    International Nuclear Information System (INIS)

    Ishioka, J.; Liu, Y.H.; Shimatake, K.; Kurosawa, T.; Ichimura, K.; Toda, Y.; Oda, M.; Tanda, S.

    2010-01-01

    We report the chirality of charge density waves (CDW) in 1T-TiSe 2 by using scanning tunneling microscopy (STM) measurements. We found that the CDW intensity becomes Ia 1 :Ia 2 :Ia 3 =1:0.7±0.1:0.5±0.1, where Ia i (i=1, 2, 3) is the amplitude of the tunneling current contributed by the CDWs. We found two states, in which the three intensity peaks of the CDW decrease clockwise and anticlockwise when we index each nesting vector in order of intensity in the Fourier transformation of the STM images. We found that this difference arises from CDW stacking along the c-axis at intervals of 2c 0 /3. This chirality is attributed to the helical stacking such as cholesteric liquid crystals.

  14. Simulated structure and imaging of NTCDI on Si(1 1 1)-7 × 7 : a combined STM, NC-AFM and DFT study

    Science.gov (United States)

    Jarvis, S. P.; Sweetman, A. M.; Lekkas, I.; Champness, N. R.; Kantorovich, L.; Moriarty, P.

    2015-02-01

    The adsorption of naphthalene tetracarboxylic diimide (NTCDI) on Si(1 1 1)-7 × 7 is investigated through a combination of scanning tunnelling microscopy (STM), noncontact atomic force microscopy (NC-AFM) and density functional theory (DFT) calculations. We show that NTCDI adopts multiple planar adsorption geometries on the Si(1 1 1)-7 × 7 surface which can be imaged with intramolecular bond resolution using NC-AFM. DFT calculations reveal adsorption is dominated by covalent bond formation between the molecular oxygen atoms and the surface silicon adatoms. The chemisorption of the molecule is found to induce subtle distortions to the molecular structure, which are observed in NC-AFM images.

  15. Mergers, Acquisitions, and Access: STM Publishing Today

    Science.gov (United States)

    Robertson, Kathleen

    Electronic publishing is changing the fundamentals of the entire printing/delivery/archive system that has served as the distribution mechanism for scientific research over the last century and a half. The merger-mania of the last 20 years, preprint pools, and publishers' licensing and journals-bundling plans are among the phenomena impacting the scientific information field. Science-Technology-Medical (STM) publishing is experiencing a period of intense consolidation and reorganization. This paper gives an overview of the economic factors fueling these trends, the major STM publishers, and the government regulatory bodies that referee this industry in Europe, Canada, and the USA.

  16. A combined optical, SEM and STM study of growth spirals

    Indian Academy of Sciences (India)

    Some novel results of a combined sequential study of growth spirals on the basal surface of the richly polytypic CdI2 crystals by optical microscopy, scanning electron microscopy (SEM) and scanning tunneling microscopy (STM) are presented and discussed. In confirmation of the known structural data, the STM pictures ...

  17. STM contrast of a CO dimer on a Cu(1 1 1) surface: a wave-function analysis

    Science.gov (United States)

    Gustafsson, Alexander; Paulsson, Magnus

    2017-12-01

    We present a method used to intuitively interpret the scanning tunneling microscopy (STM) contrast by investigating individual wave functions originating from the substrate and tip side. We use localized basis orbital density functional theory, and propagate the wave functions into the vacuum region at a real-space grid, including averaging over the lateral reciprocal space. Optimization by means of the method of Lagrange multipliers is implemented to perform a unitary transformation of the wave functions in the middle of the vacuum region. The method enables (i) reduction of the number of contributing tip-substrate wave function combinations used in the corresponding transmission matrix, and (ii) to bundle up wave functions with similar symmetry in the lateral plane, so that (iii) an intuitive understanding of the STM contrast can be achieved. The theory is applied to a CO dimer adsorbed on a Cu(1 1 1) surface scanned by a single-atom Cu tip, whose STM image is discussed in detail by the outlined method.

  18. STM contrast of a CO dimer on a Cu(1 1 1) surface: a wave-function analysis.

    Science.gov (United States)

    Gustafsson, Alexander; Paulsson, Magnus

    2017-12-20

    We present a method used to intuitively interpret the scanning tunneling microscopy (STM) contrast by investigating individual wave functions originating from the substrate and tip side. We use localized basis orbital density functional theory, and propagate the wave functions into the vacuum region at a real-space grid, including averaging over the lateral reciprocal space. Optimization by means of the method of Lagrange multipliers is implemented to perform a unitary transformation of the wave functions in the middle of the vacuum region. The method enables (i) reduction of the number of contributing tip-substrate wave function combinations used in the corresponding transmission matrix, and (ii) to bundle up wave functions with similar symmetry in the lateral plane, so that (iii) an intuitive understanding of the STM contrast can be achieved. The theory is applied to a CO dimer adsorbed on a Cu(1 1 1) surface scanned by a single-atom Cu tip, whose STM image is discussed in detail by the outlined method.

  19. Prototyping the HPDP Chip on STM 65 NM Process

    Science.gov (United States)

    Papadas, C.; Dramitinos, G.; Syed, M.; Helfers, T.; Dedes, G.; Schoellkopf, J.-P.; Dugoujon, L.

    2011-08-01

    Currently Astrium GmbH is involved in the of the High Performance Data Processor (HPDP) development programme for telecommunication applications under a DLR contract. The HPDP project targets the implementation of the commercially available reconfigurable array processor IP (XPP from the company PACT XPP Technologies) in a radiation hardened technology.In the current complementary development phase funded under the Greek Industry Incentive scheme, it is planned to prototype the HPDP chip in commercial STM 65 nm technology. In addition it is also planned to utilise the preliminary radiation hardened components of this library wherever possible.This abstract gives an overview of the HPDP chip architecture, the basic details of the STM 65 nm process and the design flow foreseen for the prototyping. The paper will discuss the development and integration issues involved in using the STM 65 nm process (also including the available preliminary radiation hardened components) for designs targeted to be used in space applications.

  20. Temperature suppression of STM-induced desorption of hydrogen on Si(100) surfaces

    DEFF Research Database (Denmark)

    Thirstrup, C.; Sakurai, M.; Nakayama, T.

    1999-01-01

    The temperature dependence of hydrogen (H) desorption from Si(100) H-terminated surfaces by a scanning tunneling microscope (STM) is reported for negative sample bias. It is found that the STM induced H desorption rate (R) decreases several orders of magnitude when the substrate temperature...

  1. STM tunneling through a quantum wire with a side-attached impurity

    International Nuclear Information System (INIS)

    Kwapinski, T.; Krawiec, M.; Jalochowski, M.

    2008-01-01

    The STM tunneling through a quantum wire (QW) with a side-attached impurity (atom, island) is investigated using a tight-binding model and the non-equilibrium Keldysh Green function method. The impurity can be coupled to one or more QW atoms. The presence of the impurity strongly modifies the local density of states of the wire atoms, thus influences the STM tunneling through all the wire atoms. The transport properties of the impurity itself are also investigated mainly as a function of the wire length and the way it is coupled to the wire. It is shown that the properties of the impurity itself and the way it is coupled to the wire strongly influence the STM tunneling, the density of states and differential conductance

  2. 'Felson Signs' revisited

    International Nuclear Information System (INIS)

    George, Phiji P.; Irodi, Aparna; Keshava, Shyamkumar N.; Lamont, Anthony C.

    2014-01-01

    In this article we revisit, with the help of images, those classic signs in chest radiography described by Dr Benjamin Felson himself, or other illustrious radiologists of his time, cited and discussed in 'Chest Roentgenology'. We briefly describe the causes of the signs, their utility and the differential diagnosis to be considered when each sign is seen. Wherever possible, we use CT images to illustrate the basis of some of these classic radiographic signs.

  3. STM in liquids. A scanning tunneling microscopy exploration of the liquid-solid interface.

    NARCIS (Netherlands)

    Hulsken, B.

    2008-01-01

    This thesis reports of a series of atomic scale studies of the liquid-solid interface, carried out with a home-built liquid-cell Scanning Tunnelling Microscope (STM). The home-built liquid-cell STM is described in detail, and numerical simulations are performed to show that surfaces immersed in the

  4. STM study on surface relief, ultra-fine structure and transformation mechanism of bainite in steels

    International Nuclear Information System (INIS)

    Fang, H.S.; Yang, Z.G.; Wang, J.J.; Zheng, Y.K.

    1995-01-01

    The surface reliefs accompanying lower bainite transformation in steels have been studied by scanning tunneling microscopy (STM). With the exclusive vertical resolution of STM, we observed that the surface relief associated with bainite is a group of surface reliefs related to subplates, subunits and sub-subunits. From the bainite plate to the sub-subunit in it, the reliefs are in a tent shape, not of invariant plane strain (IPS) type. The fine structure of bainite in a steel has also been shown by STM and TEM that bainite plate is composed of subplates, subunits and sub-subunits. On the basis of the fine structure inside a bainitic ferrite plate observed under STM, sympathetic-ledgewise mechanism of bainite formation is proposed. (orig.)

  5. changing stm curricula for the information age: implications

    African Journals Online (AJOL)

    TONIA CLARE

    information age, rationale and strategies for changing STM curricular, implications for the teacher and then conclusion. ... learner under the guidance of a school to effect a change in the ..... education international conference. Ofele, C. N. ...

  6. Theoretical STM maps of curved graphene

    Science.gov (United States)

    Diniz, G. S.; Ulloa, S. E.

    2010-03-01

    We calculate the effect of curvature on the electronic states in monolayer graphene, considering a local ripple along different directions on the plane. The curvature introduces hybridization between σ and π bands and affects the electronic structure and associated wave functions, even opening a gap of the order of few meV at the Dirac point. Our calculation uses a non-orthogonal four-orbital tight-binding representation up to nearest-neighbors, which fully describes the electronic states of the structure. We focus this study on the analysis of theoretical STM maps for different ripple directions and radius of curvature. We discuss the appearance of a well defined pattern in the STM map near the Dirac point, which is strongly modified when the graphene is rippled along different directions, and discuss this effect in terms of a geometric Berry phase. Although it is difficult experimentally to produce and control a well defined direction for the graphene ripple, recent experiments suggest that this structure may be possible in suspended samples with stressors along the edges [1].[4pt] [1] W. Bao et al., Nature Nanotech. 4, 562 (2009).

  7. Superconducting phase transition in STM tips

    Energy Technology Data Exchange (ETDEWEB)

    Eltschka, Matthias; Jaeck, Berthold; Assig, Maximilian; Etzkorn, Markus; Ast, Christian R. [Max Planck Institute for Solid State Research, Stuttgart (Germany); Kern, Klaus [Max Planck Institute for Solid State Research, Stuttgart (Germany); Ecole Polytechnique Federale de Lausanne (Switzerland)

    2015-07-01

    The superconducting properties of systems with dimensions comparable to the London penetration depth considerably differ from macroscopic systems. We have studied the superconducting phase transition of vanadium STM tips in external magnetic fields. Employing Maki's theory we extract the superconducting parameters such as the gap or the Zeeman splitting from differential conductance spectra. While the Zeeman splitting follows the theoretical description of a system with s=1/2 and g=2, the superconducting gaps as well as the critical fields depend on the specific tip. For a better understanding of the experimental results, we solve a one dimensional Usadel equation modeling the superconducting tip as a cone with the opening angle α in an external magnetic field. We find that only a small region at the apex of the tip is superconducting in high magnetic fields and that the order of the phase transition is directly determined by α. Further, the spectral broadening increases with α indicating an intrinsic broadening mechanism due to the conical shape of the tip. Comparing these calculations to our experimental results reveals the order of the superconducting phase transition of the STM tips.

  8. In Situ STM and AFM of the Copper Protein Pseudomonas Aeruginosa Azurin

    DEFF Research Database (Denmark)

    Friis, Esben P.; Andersen, Jens Enevold Thaulov; Madsen, L.L.

    1997-01-01

    to gold and facile electron tunnel routes between this group and the copper atom. Azurin adsorbed on Au(111) can be imaged to molecular resolution by in situ STM and shows regular arrays of individual structures corresponding well to the known molecular size of azurin. The current falls off approximately...... exponentially with increasing distance with a decay constant of 0.4–0.5 Å−1. In comparison in situ AFM shows structures laterally convoluted with the tip while the vertical extension is in the same range as the structural size of azurin. The results are of interest in relation to electron tunnel mechanisms...

  9. STM-electroluminescence from clustered C3N4 nanodomains synthesized via green chemistry process.

    Science.gov (United States)

    Andrade, E P; Costa, B B A; Chaves, C R; de Paula, A M; Cury, L A; Malachias, A; Safar, G A M

    2018-01-01

    A Scanning Tunneling Microscopy/Spectroscopy (STM/STS) and synchrotron X-ray diffraction study on clustered C 3 N 4 nanoparticles (nanoflakes) is conducted on green-chemistry synthesized samples obtained from chitosan through high power sonication. Morphological aspects and the electronic characteristics are investigated. The observed bandgap of the nanoflakes reveals the presence of different phases in the material. Combining STM morphology, STS spectra and X-ray diffraction (XRD) results one finds that the most abundant phase is graphitic C 3 N 4 . A high density of defects is inferred from the XRD measurements. Additionally, STM-electroluminescence (STMEL) is detected in C 3 N 4 nanoflakes deposited on a gold substrate. The tunneling current creates photons that are three times more energetic than the tunneling electrons of the STM sample. We ponder about the two most probable models to explain the observed photon emission energy: either a nonlinear optical phenomenon or a localized state emission. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Tip-Dependent Scanning Tunneling Microscopy Imaging of Ultrathin FeO Films on Pt(111)

    DEFF Research Database (Denmark)

    Merte, Lindsay Richard; Grabow, Lars C.; Peng, Guowen

    2011-01-01

    High-resolution scanning tunneling microscope (STM) images of moiré-structured FeO films on Pt(111) were obtained in a number of different tip-dependent imaging modes. For the first time, the STM images are distinguished and interpreted unambiguously with the help of distinct oxygen...

  11. Orientation-dependent imaging of electronically excited quantum dots

    Science.gov (United States)

    Nguyen, Duc; Goings, Joshua J.; Nguyen, Huy A.; Lyding, Joseph; Li, Xiaosong; Gruebele, Martin

    2018-02-01

    We previously demonstrated that we can image electronic excitations of quantum dots by single-molecule absorption scanning tunneling microscopy (SMA-STM). With this technique, a modulated laser beam periodically saturates an electronic transition of a single nanoparticle, and the resulting tunneling current modulation ΔI(x0, y0) maps out the SMA-STM image. In this paper, we first derive the basic theory to calculate ΔI(x0, y0) in the one-electron approximation. For near-resonant tunneling through an empty orbital "i" of the nanostructure, the SMA-STM signal is approximately proportional to the electron density |φi) (x0,y0)|nudge quantum dots on the surface and roll them, thus imaging excited state electronic structure of a single quantum dot at different orientations. We use density functional theory to model ODMs at various orientations, for qualitative comparison with the SMA-STM experiment. The model demonstrates that our experimentally observed signal monitors excited states, localized by defects near the surface of an individual quantum dot. The sub-nanometer super-resolution imaging technique demonstrated here could become useful for mapping out the three-dimensional structure of excited states localized by defects within nanomaterials.

  12. Design and implementation of FIR filter based on STM32F103x

    Directory of Open Access Journals (Sweden)

    ZHENG Zhendong

    2013-08-01

    Full Text Available STM32F1 series processors are based on ST's new generation of ARM cortex-M3 processor core to meet the industrial control,medical,consumer and other areas of application requirements. At the same time,ST companies also launched a set of DSP function library for the STM32F10x series,enabling common digital signal processing. In this paper,a set of FIRfilter design and implementation is proposed for the STM32F10x series. Experiments show that the integer filter coefficients can replace the float coefficients in FIRfilter design. When the sampling rate is 256 samples per second,the FIRfilter is of the order of 128 and takes only 1.5ms to finish filtering 256 samples,fully meeting the design requirements for industrial control systems.

  13. Diffusion of anthracene derivatives on Cu(111) studied by STM and DFT

    Science.gov (United States)

    Wyrick, Jonathan; Bartels, Ludwig; Einstein, Theodore

    2014-03-01

    Substituted anthracenes have drawn attention due to their ability to diffuse uniaxially on a Cu(111) surface. We compare anthracene to three of its derivatives whose 9,10 hydrogens are replaced by elements of the chalcogen group that act as linkers binding the molecules to a Cu(111) substrate. DFT calculations shed light on STM imaging and diffusion studies on the three substituted species. We present an analysis of the DFT results in which energetic contributions to the diffusion barriers are partitioned among the Kohn-Sham orbitals, allowing us to make assignments as to how each orbital affects diffusion for each species and draw comparisons between them. Present address: Center for Nanoscale Science and Technology, NIST, Gaithersburg, MD.

  14. Fermi surface contours obtained from scanning tunneling microscope images around surface point defects

    International Nuclear Information System (INIS)

    Khotkevych-Sanina, N V; Kolesnichenko, Yu A; Van Ruitenbeek, J M

    2013-01-01

    We present a theoretical analysis of the standing wave patterns in scanning tunneling microscope (STM) images, which occur around surface point defects. We consider arbitrary dispersion relations for the surface states and calculate the conductance for a system containing a small-size tunnel contact and a surface impurity. We find rigorous theoretical relations between the interference patterns in the real-space STM images, their Fourier transforms and the Fermi contours of two-dimensional electrons. We propose a new method for reconstructing Fermi contours of surface electron states, directly from the real-space STM images around isolated surface defects. (paper)

  15. Upgrade of the Surface Spectrometer at NEPOMUC for PAES, XPS and STM Investigations

    Science.gov (United States)

    Zimnik, S.; Lippert, F.; Hugenschmidt, C.

    2014-04-01

    The characterization of the elemental composition of surfaces is of great importance for the understanding of many surface processes, such as surface segregation or oxidation. Positron-annihilation-induced Auger Electron Spectroscopy (PAES) is a powerful technique for gathering information about the elemental composition of only the topmost atomic layer of a sample. The upgraded surface spectrometer at NEPOMUC (NEtron induced POsitron source MUniCh) enables a comprehensive surface analysis with the complementary techniques STM, XPS and PAES. A new X-ray source for X-ray induced photoelectron spectroscopy (XPS) was installed to gather additional information on oxidation states. A new scanning tunneling microscope (STM) is used as a complementary method to investigate with atomic resolution the surface electron density. The combination of PAES, XPS and STM allows the characterization of both the elemental composition, and the surface topology.

  16. STM-induced light emission from vacuum-evaporated gold film

    Indian Academy of Sciences (India)

    Administrator

    ... investigations of individual surface nanostructures,10–12 light to be detected is fundamentally weak owing to the low efficiency of excitation by tunnel- ... signal level can be improved by measuring STM-LE in a prism-coupled configuration.

  17. Deducing 2D Crystal Structure at the Solid/Liquid Interface with Atomic Resolution by Combined STM and SFG Study

    Science.gov (United States)

    McClelland, Arthur; Ahn, Seokhoon; Matzger, Adam J.; Chen, Zhan

    2009-03-01

    Supplemented by computed models, Scanning Tunneling Microscopy (STM) can provide detailed structure of 2D crystals formed at the liquid/solid interface with atomic resolution. However, some structural information such as functional group orientations in such 2D crystals needs to be tested experimentally to ensure the accuracy of the deduced structures. Due to the limited sensitivity, many other experimental techniques such as Raman and infrared spectroscopy have not been allowed to provide such structural information of 2D crystals. Here we showed that Sum Frequency Generation Vibrational Spectroscopy (SFG) can measure average orientation of functional groups in such 2D crystals, or physisorbed monolayers, providing key experimental data to aid in the modeling and interpretation of the STM images. The usefulness of combining these two techniques is demonstrated with a phthalate diesters monolayer formed at the 1-phenyloctane/ highly oriented pyrolytic graphite (HOPG) interface. The spatial orientation of the ester C=O of the monolayer was successfully determined using SFG.

  18. Surface assisted oxidation of flat lying organic molecules - a real-time STM study

    Energy Technology Data Exchange (ETDEWEB)

    Waldmann, Thomas; Roos, Michael; Breitruck, Achim; Hoster, Harry E.; Behm, R. Juergen [Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm (Germany); Kuenzel, Daniela; Gross, Axel [Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm (Germany)

    2010-07-01

    Using time resolved scanning tunneling microscopy (STM), we tested the interaction of O{sub 2} from gas-phase with ordered adlayers of the Bis(terpyridine) derivative 2,4'-BTP on Au(111), Ag(111) and graphite (HOPG) surfaces at T = 300 K. At an O{sub 2} pressure of 10{sup -5} mbar, the adlayers on Ag(111) undergo chemical and structural changes. These include modifications of the 2-pyridyl rings of individual 2,4'-BTP adsorbates and rearrangements of the hydrogen bonded adlayer. Since we do not observe similar changes on HOPG and Au(111), we assume that Ag(111) acts as catalyst for the underlying processes. Based on our STM data in combination with DFT calculations, we conclude that the observed reaction is pyridyl-N-oxide formation. Furthermore, we derive reaction yields, enantiomeric excess, reaction rates and reaction orders from the time-resolved STM data.

  19. Electric field effects in scanning tunneling microscope imaging

    DEFF Research Database (Denmark)

    Stokbro, Kurt; Quaade, Ulrich; Grey, Francois

    1998-01-01

    We present a high-voltage extension of the Tersoff-Hamann theory of scanning tunneling microscope (STM) images, which includes the effect of the electric field between the tip and the sample. The theoretical model is based on first-principles electronic structure calculations and has no adjustable...... parameters. We use the method to calculate theoretical STM images of the monohydrate Si(100)-H(2x1) surface with missing hydrogen defects at -2V and find an enhanced corrugation due to the electric field, in good agreement with experimental images....

  20. Comparison of GaP and PH3 as dopant sources for STM-based device fabrication

    International Nuclear Information System (INIS)

    Goh, Kuan Eng Johnson; Oberbeck, L; Butcher, M J; Curson, N J; Ruess, F J; Simmons, M Y

    2007-01-01

    We present a comparative study of the use of a GaP solid source as an alternative to gaseous PH 3 for controlled phosphorus δ-doping of lithographic patterns on H:Si(001) fabricated by scanning tunnelling microscopy (STM). Whilst our electrical studies show that P δ-doping of Si with the GaP solid source and gaseous PH 3 result in essentially the same electrical characteristics, our STM studies reveal that P 2 molecules from the GaP source exhibit a lower selectivity between bare Si(001) and H:Si(001) compared to PH 3 molecules. We discuss the significance of our findings in the context of fabricating nanoscale P dopant devices in Si using STM-based lithography

  1. Electroluminescence spectra of an STM-tip-induced quantum dot

    NARCIS (Netherlands)

    Croitoru, M.D.; Gladilin, V.N.; Fomin, V.; Devreese, J.T.; Kemerink, M.; Koenraad, P.M.; Sauthoff, K.; Wolter, J.H.; Long, A.R.; Davies, J.H.

    2003-01-01

    We analyse the electroluminescence measurements performed on a STM-tipImduced quantum dot in a GaAs layer. Positions of electroluminescence peaks, attributed to the electron-hole recombination in the quantum dot, are very sensitive to the electron tunnelling current even in the case when the current

  2. In Situ Studies of Surface Mobility on Noble Metal Model Catalysts Using STM and XPS at Ambient Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, Derek Robert [Univ. of California, Berkeley, CA (United States)

    2010-06-01

    High Pressure Scanning Tunneling Microscopy (HP-STM) and Ambient Pressure X-ray Photoelectron Spectroscopy were used to study the structural properties and catalytic behavior of noble metal surfaces at high pressure. HP-STM was used to study the structural rearrangement of the top most atomic surface layer of the metal surfaces in response to changes in gas pressure and reactive conditions. AP-XPS was applied to single crystal and nanoparticle systems to monitor changes in the chemical composition of the surface layer in response to changing gas conditions. STM studies on the Pt(100) crystal face showed the lifting of the Pt(100)-hex surface reconstruction in the presence of CO, H2, and Benzene. The gas adsorption and subsequent charge transfer relieves the surface strain caused by the low coordination number of the (100) surface atoms allowing the formation of a (1 x 1) surface structure commensurate with the bulk terminated crystal structure. The surface phase change causes a transformation of the surface layer from hexagonal packing geometry to a four-fold symmetric surface which is rich in atomic defects. Lifting the hex reconstruction at room temperature resulted in a surface structure decorated with 2-3 nm Pt adatom islands with a high density of step edge sites. Annealing the surface at a modest temperature (150 C) in the presence of a high pressure of CO or H2 increased the surface diffusion of the Pt atoms causing the adatom islands to aggregate reducing the surface concentration of low coordination defect sites. Ethylene hydrogenation was studied on the Pt(100) surface using HP-STM. At low pressure, the lifting of the hex reconstruction was observed in the STM images. Increasing the ethylene pressure to 1 Torr, was found to regenerate the hexagonally symmetric reconstructed phase. At room temperature ethylene undergoes a structural rearrangement to form ethylidyne. Ethylidyne preferentially binds at the three-fold hollow sites, which

  3. Direct Fabrication of Carbon Nanotubes STM Tips by Liquid Catalyst-Assisted Microwave Plasma-Enhanced Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Fa-Kuei Tung

    2009-01-01

    Full Text Available Direct and facile method to make carbon nanotube (CNT tips for scanning tunneling microscopy (STM is presented. Cobalt (Co particles, as catalysts, are electrochemically deposited on the apex of tungsten (W STM tip for CNT growth. It is found that the quantity of Co particles is well controlled by applied DC voltage, concentration of catalyst solution, and deposition time. Using optimum growth condition, CNTs are successfully synthesized on the tip apex by catalyst-assisted microwave-enhanced chemical vapor deposition (CA-MPECVD. A HOPG surface is clearly observed at an atomic scale using the present CNT-STM tip.

  4. A method employing STM for the estimation of relative changes in ...

    Indian Academy of Sciences (India)

    – spectroscopy; scanning tunneling microscope; workfunction. Abstract. – spectroscopy measurements using a scanning tunnelling microscope (STM) were carried out to determine the change in the work function of a W ... Current Issue

  5. PENGARUH MODEL PEMBELAJARAN SAINS TEKNOLOGI MASYARAKAT (STM TERHADAP KEMAMPUAN PEMECAHAN MASALAH DAN SELF-EFFICACY SISWA

    Directory of Open Access Journals (Sweden)

    M. Dwipayana

    2017-10-01

    Full Text Available Penelitian ini bertujuan menganalisis perbedaan kemampuan pemecahan masalah dan self-efficacy siswa antara kelompok siswa yang belajar dengan model pembelajaran Sains Teknologi Masyarakat (STM dibandingkan dengan kelompok siswa yang belajar dengan model pembelajaran langsung (Direct Instruction. Jenis penelitian ini adalah penelitian semu (quasi experiment dengan rancangan pretest-posttest non equivalent control group design Populasi dalam penelitian ini semua siswa kelas VII SMP 2 Singaraja dan sampel sebanyak 75 orang siswa. Data self-efficacy dikumpulkan dengan metode kuisioner dan data kemampuan pemecahan masalah dikumpulkan dengan tes essay. Analisis data yang digunakan dalam penelitian ini adalah Manova. Berdasarkan penelitian yang telah dilakukan didapatkan hasil bahwa terdapat perbedaan kemampuan pemecahan masalah dan self- efficacy siswa antara kelompok siswa yang belajar dengan model pembelajaran STM dibandingkan dengan kelompok siswa yang belajar dengan model pembelajaran langsung (Direct Instruction dengan rata-rata nilai gain score STM lebih unggul dari nilai gain score DI berturut-turut yaitu 0,53>0,48 pada variabel kemampuan pemecahan masalah dan 0,55>0,41 pada variabel self-efficacy. Hasil Uji LSD menunjukan gain score kemampuan pemecahan masalah dan self-efficacy antara kelompok siswa yang belajar dengan model pembelajaran STM lebih baik dibandingkan dengan kelompok siswa yang belajar dengan model pembelajaran langsung (Direct Instruction.

  6. Comparison of GaP and PH{sub 3} as dopant sources for STM-based device fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Goh, Kuan Eng Johnson [Australian Research Council Centre of Excellence for Quantum Computer Technology, University of New South Wales, Sydney, New South Wales 2052 (Australia); Oberbeck, L [Australian Research Council Centre of Excellence for Quantum Computer Technology, University of New South Wales, Sydney, New South Wales 2052 (Australia); Butcher, M J [School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Curson, N J [Australian Research Council Centre of Excellence for Quantum Computer Technology, University of New South Wales, Sydney, New South Wales 2052 (Australia); Ruess, F J [Australian Research Council Centre of Excellence for Quantum Computer Technology, University of New South Wales, Sydney, New South Wales 2052 (Australia); Simmons, M Y [Australian Research Council Centre of Excellence for Quantum Computer Technology, University of New South Wales, Sydney, New South Wales 2052 (Australia)

    2007-02-14

    We present a comparative study of the use of a GaP solid source as an alternative to gaseous PH{sub 3} for controlled phosphorus {delta}-doping of lithographic patterns on H:Si(001) fabricated by scanning tunnelling microscopy (STM). Whilst our electrical studies show that P {delta}-doping of Si with the GaP solid source and gaseous PH{sub 3} result in essentially the same electrical characteristics, our STM studies reveal that P{sub 2} molecules from the GaP source exhibit a lower selectivity between bare Si(001) and H:Si(001) compared to PH{sub 3} molecules. We discuss the significance of our findings in the context of fabricating nanoscale P dopant devices in Si using STM-based lithography.

  7. Synthesis, electrochemistry, STM investigation of oligothiophene self-assemblies with superior structural order and electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, Cheng-Yu [C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Liu, Yinghao; Yarotski, Dmitry [Center of Integrated Nanotechnologies, Materials Physics and Application Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Li, Hao [Theory Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Xu, Ping; Yen, Hung-Ju [C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Tretiak, Sergei, E-mail: serg@lanl.gov [Theory Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Wang, Hsing-Lin, E-mail: hwang@lanl.gov [C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2016-12-20

    Graphical abstract: STM imaging reveals differently oriented domains of self-assembled tetrathiophene molecules. - Highlights: • Optical and redox properties of oligothiophene derivatives are studied. • Packing pattern of self-assembly monolayer depends on the conjugation length. • Strong electronic coupling and three redox couples in cyclic voltamogram are observed in the hierarchical self-assembly. - Abstract: Three oligothiophene (terthiophene, tetrathiophene and pentathiophene) derivatives are synthesized and their monolayer self-assemblies on gold (Au) are prepared via Au–S covalent bond. Our UV–Vis experimental characterization of solution reveals the dependence of the optical properties on the conjugation length of the oligothiophenes, which compares well with Time-Dependent Density Functional Theory (TDDFT) simulations of spectra of individual chromophores. Photoluminescent spectra of thin films show pronounced red shifts compared to that of solutions, suggesting strong inter-oligomer interactions. The comparative studies of cyclic voltammograms of tetrathiophene from solution, cast film and self-assembled monolayer (SAM) indicate presence of one, two, and three oxidized species in these samples, respectively, suggesting a very strong electronic coupling between tetrathiophene molecules in the SAM. Scanning tunneling microscopy (STM) imaging of SAMs of the tetrathiophene on an atomically flat Au surface exhibits formation of monolayer assemblies with molecular order, and the molecular packing appears to show an overlay of oligothiophene molecules on top of another one. In contrast, the trimer and pentamer images show only aggregated species lacking long-range order on the molecular level. Such trends in going from disordered–ordered–disordered monolayer assemblies are mainly due to a delicate balance between inter-chromophore π–π couplings, hydrophobic interaction and the propensity to form Au–S covalent bond. Such hypothesis has been

  8. Why does the disorder of R-pn and rac-pn ligands in the quasi-one-dimensional bromo-bridged NiIII complexes, [Ni(pn)2Br]Br2 (pn=1,2-diaminopropane) afford similar STM patterns?

    Science.gov (United States)

    Wu, Hashen; Kawakami, Daisuke; Sasaki, Mari; Xie, Jimin; Takaishi, Shinya; Kajiwara, Takashi; Miyasaka, Hitoshi; Yamashita, Masahiro; Matsuzaki, Hiroyuki; Okamoto, Hiroshi

    2007-09-03

    The disordered patterns of R- and rac-1,2-diaminopropane (pn) in quasi-one-dimensional bromo-bridged Ni(III) complexes, [NiIII(pn)2Br]Br2, have been investigated by single-crystal X-ray structure determination and scanning tunneling microscopy (STM). X-ray structure determination shows that the methyl moieties are disordered on the right- and left-hand sides with half occupancies in both compounds, while the carbon atoms of the ethylene moieties of pn ligands are disordered in [Ni(rac-pn)2Br]Br2 and not disordered in [Ni(R-pn)2Br]Br2. In the STM images of both compounds, the bright spots are not straight but fluctuated with the similar patterns. We have concluded that tunnel current from the STM tip to metal ions are detected via methyl groups of pn ligands.

  9. Nanoscopic Studies on Polymer Molecules(STM-other surfaces)

    OpenAIRE

    Toshio, NISHI; Ken, NAKAJIMA; Takayuki, IKEHARA; Department of Applied Physics, School of Engineering, The University of Tokyo; Department of Applied Physics, School of Engineering, The University of Tokyo; Department of Applied Physics, School of Engineering, The University of Tokyo

    1997-01-01

    A new field of study in the polymer science and engineering is being opened with the use of scanning tunneling microscope (STM), atomic force microscope (AFM), and scanning probe microscope (SPM). In this short review article several examples are given with comments. They are direct observation of poly(macromonomer), structure of a cross-linking domain of a gel, and observation of topochemically photopolymerizable conjugated aromatic compound. Moreover, nanorheological properties of polymer b...

  10. A method employing STM for the estimation of relative changes in ...

    Indian Academy of Sciences (India)

    Unknown

    determine the change in the work function of a W tip following one monolayer (1 ML) deposition of Ni and subsequent annealing at 700 K. The variation in the actual gap voltage obtained ... Studies using STM mostly concentrate on work func-.

  11. Photoluminescence characteristics of InAs quantum dots grown by STM/MBE site-control technique

    Energy Technology Data Exchange (ETDEWEB)

    Nishikawa, S.; Kohmoto, S.; Nakamura, H.; Ishikawa, T.; Asakawa, K.; Wada, O. [Femtosecond Technology Research Association, Tsukuba, Ibaraki (Japan). FESTA Lab.

    2001-03-08

    This paper describes micro-photoluminescence (PL) analysis of site-controlled QDs (SCQDs) grown using a novel in-situ MBE growth technique in which sites of self-assembled InAs QDs are controlled by forming nanometer deposits using a scanning tunneling microscope (STM) probe. We found from the temperature dependence of PL that the carrier collection at QDs at low temperature is limited by carrier diffusion in the wetting layer. The analysis of PL data considering this effect has indicated that individual QDs grown have high crystalline quality in spite of the addition of an artificial STM process during growth. (orig.)

  12. Simulation of STM technique for electron transport through boron-nitride nanotubes

    International Nuclear Information System (INIS)

    Ganji, M.D.; Mohammadi-nejad, A.

    2008-01-01

    We report first-principles calculations on the electrical transport properties of boron-nitrid nanotubes (BNNTs). We consider a single walled (5,0) boron-nitrid nanotube sandwiched between an Au(1 0 0) substrate and a monatomic Au scanning tunneling microscope (STM) tip. Lateral motion of the tip over the nanotube wall cause it to change from one conformation class to the others and to switch between a strongly and a weakly conducting state. Thus, surprisingly, despite their apparent simplicity these Au/BNNT/Au nanowires are shown to be a convenient switch. Experiments with a conventional STM are proposed to test these predictions. The projection of the density of states (PDOS) and the transmission coefficients T(E) of the two-probe systems at zero bias are analyzed, and it suggests that the variation of the coupling between the wire and the electrodes leads to switching behaviour

  13. Preparation of theoretical scanning tunneling microscope images of adsorbed molecules: a theoretical study of benzene on the Cu(110) surface

    International Nuclear Information System (INIS)

    Shapter, J.G.; Rogers, B.L.; Ford, M.J.

    2003-01-01

    Full text: Since its development in 1982, the Scanning Tunneling Microscope (STM) has developed into a powerful tool for the study of surfaces and adsorbates. However, the utility of the technique can be further enhanced through the development of techniques for generating theoretical STM images. This is particularly true when studying molecules adsorbed on a substrate, as the results are often interpreted superficially due to an inadequate understanding of the orbital overlap probed in the experiment. A method of preparing theoretical scanning tunneling microscope (STM) images using comparatively inexpensive desktop computers and the commercially available CRYSTAL98 package is presented through a study of benzene adsorbed on the Cu(110) surface. Density Functional Theory (DFT) and Hartree-Fock (HF) methods are used to model clean Cu(110) slabs of various thicknesses and to simulate the adsorption of benzene onto these slabs. Eight possible orientations of benzene on the Cu(110) surface are proposed, and the optimum orientation according to the calculations is presented. Theoretical STM images of the Cu(110) surface and benzene adsorbed on the Cu(110) surface are compared with experimental STM images of the system from a published study. Significant differences are observed and are examined in detail

  14. Revisited

    DEFF Research Database (Denmark)

    Tegtmeier, Silke; Meyer, Verena; Pakura, Stefanie

    2017-01-01

    were captured when they described entrepreneurs. Therefore, this paper aims to revisit gender role stereotypes among young adults. Design/methodology/approach: To measure stereotyping, participants were asked to describe entrepreneurs in general and either women or men in general. The Schein......Purpose: Entrepreneurship is shaped by a male norm, which has been widely demonstrated in qualitative studies. The authors strive to complement these methods by a quantitative approach. First, gender role stereotypes were measured in entrepreneurship. Second, the explicit notions of participants......: The images of men and entrepreneurs show a high and significant congruence (r = 0.803), mostly in those adjectives that are untypical for men and entrepreneurs. The congruence of women and entrepreneurs was low (r = 0.152) and insignificant. Contrary to the participants’ beliefs, their explicit notions did...

  15. Thermally oxidized Inconel 600 and 690 nickel-based alloys characterizations by combination of global photoelectrochemistry and local near-field microscopy techniques (STM, STS, AFM, SKPFM)

    Science.gov (United States)

    Mechehoud, F.; Benaioun, N. E.; Hakiki, N. E.; Khelil, A.; Simon, L.; Bubendorff, J. L.

    2018-03-01

    Thermally oxidized nickel-based alloys are studied by scanning tunnelling microscopy (STM), scanning tunnelling spectroscopy (STS), atomic force microscopy (AFM), scanning kelvin probe force microscopy (SKPFM) and photoelectro-chemical techniques as a function of oxidation time at a fixed temperature of 623 K. By photoelectrochemistry measurements we identify the formation of three oxides NiO, Fe2O3, Cr2O3 and determine the corresponding gap values. We use these values as parameter for imaging the surface at high bias voltage by STM allowing the spatial localization and identification of both NiO, Fe2O3 oxide phases using STS measurements. Associated to Kelvin probe measurements we show also that STS allow to distinguished NiO from Cr2O3 and confirm that the Cr2O3 is not visible at the surface and localized at the oxide/steel interface.

  16. Control by hardware of government systems for laser diodes with STM32F4 and Peltier cells; Control por hardware de sistemas de gobierno para diodos laser con STM32F4 y celdas Peltier

    Energy Technology Data Exchange (ETDEWEB)

    Ulloa Solano, Natalia Irina

    2013-07-01

    A low cost prototype of a government system is developed for laser diodes with STM32F4 microcontrollers and Peltier cooling. Commercial and homemade government system (with STM32F4 microcontrollers ) are investigated with the objective of adequately control the current of a laser diode. Characteristics of STM32F4 microcontrollers are described. The low cost platforms as the Arduino and Raspberry Pi are compared. A bibliographical and documentary compilation is realized for the preliminary study of the components and tools to use in the prototype. The theory related with the heat transfer between a laser diode and the outside, and a Peltier cell and outside is summarized. A heat dissipation model is proposed of a system formed by a laser diode and Peltier cell. A control system of current and fed back temperature is designed and implemented to allow adequately control laser diodes without and with photodiode (2 pickups and 3 pickups respectively). The viability of control with free software is studied and corroborated. The temperature control of the laser diode using a Peltier cell as cooler has been possible through a simple control of ON/OFF mode. The integration of devices such as ADC, DAC, timers and facilities of STM32F4 microcontroller, have allowed to optimize costs by hardware, save time and costs. Also, the incorporation of the Cortex-M4 processor has optimized the consumption of operational resources and has executed much of its instruction set of efficient way. Because of this, the project has complied with its maximum as to low cost is concerned [Spanish] Un prototipo de bajo costo de un sistema de gobierno es desarrollado para diodos laser con microcontroladores STM32F4 y enfriamiento con Peltier. Los sistemas de gobierno comerciales y caseros (con microcontroladores STM32F4) son investigados con el objetivo de controlar adecuadamente la corriente de un diodo laser. Las caracteristicas de los microcontroladores STM32F4 son descritas. Las plataformas de

  17. A previously uncharacterized gene stm0551 plays a repressive role in the regulation of type 1 fimbriae in Salmonella enterica serotype Typhimurium

    Directory of Open Access Journals (Sweden)

    Wang Ke-Chuan

    2012-06-01

    Full Text Available Abstract Background Salmonella enterica serotype Typhimurium produces surface-associated fimbriae that facilitate adherence of the bacteria to a variety of cells and tissues. Type 1 fimbriae with binding specificity to mannose residues are the most commonly found fimbrial type. In vitro, static-broth culture favors the growth of S. Typhimurium with type 1 fimbriae, whereas non-type 1 fimbriate bacteria are obtained by culture on solid-agar media. Previous studies demonstrated that the phenotypic expression of type 1 fimbriae is the result of the interaction and cooperation of the regulatory genes fimZ, fimY, fimW, and fimU within the fim gene cluster. Genome sequencing revealed a novel gene, stm0551, located between fimY and fimW that encodes an 11.4-kDa putative phosphodiesterase specific for the bacterial second messenger cyclic-diguanylate monophosphate (c-di-GMP. The role of stm0551 in the regulation of type 1 fimbriae in S. Typhimurium remains unclear. Results A stm0551-deleted stain constructed by allelic exchange constitutively produced type 1 fimbriae in both static-broth and solid-agar medium conditions. Quantative RT-PCR revealed that expression of the fimbrial major subunit gene, fimA, and one of the regulatory genes, fimZ, were comparably increased in the stm0551-deleted strain compared with those of the parental strain when grown on the solid-agar medium, a condition that normally inhibits expression of type 1 fimbriae. Following transformation with a plasmid possessing the coding sequence of stm0551, expression of fimA and fimZ decreased in the stm0551 mutant strain in both culture conditions, whereas transformation with the control vector pACYC184 relieved this repression. A purified STM0551 protein exhibited a phosphodiesterase activity in vitro while a point mutation in the putative EAL domain, substituting glutamic acid (E with alanine (A, of STM0551 or a FimY protein abolished this activity. Conclusions The finding that the

  18. Pd adsorption on Si(1 1 3) surface: STM and XPS study

    International Nuclear Information System (INIS)

    Hara, Shinsuke; Yoshimura, Masamichi; Ueda, Kazuyuki

    2008-01-01

    Pd-induced surface structures on Si(1 1 3) have been studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). In the initial process of the Pd adsorption below 0.10 ML, Pd silicide (Pd 2 Si) clusters are observed to form randomly on the surface. By increasing the Pd coverage to 0.10 ML, the clusters cover the entire surface, and an amorphous layer is formed. After annealing the Si(1 1 3)-Pd surface at 600 deg. C, various types of islands and chain protrusions appears. The agglomeration, coalescence and crystallization of these islands are observed by using high temperature (HT-) STM. It is also found by XPS that the islands correspond to Pd 2 Si structure. On the basis of these results, evolution of Pd-induced structures at high temperatures is in detail discussed

  19. Knowledge Extraction from Atomically Resolved Images.

    Science.gov (United States)

    Vlcek, Lukas; Maksov, Artem; Pan, Minghu; Vasudevan, Rama K; Kalinin, Sergei V

    2017-10-24

    Tremendous strides in experimental capabilities of scanning transmission electron microscopy and scanning tunneling microscopy (STM) over the past 30 years made atomically resolved imaging routine. However, consistent integration and use of atomically resolved data with generative models is unavailable, so information on local thermodynamics and other microscopic driving forces encoded in the observed atomic configurations remains hidden. Here, we present a framework based on statistical distance minimization to consistently utilize the information available from atomic configurations obtained from an atomically resolved image and extract meaningful physical interaction parameters. We illustrate the applicability of the framework on an STM image of a FeSe x Te 1-x superconductor, with the segregation of the chalcogen atoms investigated using a nonideal interacting solid solution model. This universal method makes full use of the microscopic degrees of freedom sampled in an atomically resolved image and can be extended via Bayesian inference toward unbiased model selection with uncertainty quantification.

  20. Imaging sequential dehydrogenation of methanol on Cu(110) with a scanning tunneling microscope.

    Science.gov (United States)

    Kitaguchi, Y; Shiotari, A; Okuyama, H; Hatta, S; Aruga, T

    2011-05-07

    Adsorption of methanol and its dehydrogenation on Cu(110) were studied by using a scanning tunneling microscope (STM). Upon adsorption at 12 K, methanol preferentially forms clusters on the surface. The STM could induce dehydrogenation of methanol sequentially to methoxy and formaldehyde. This enabled us to study the binding structures of these products in a single-molecule limit. Methoxy was imaged as a pair of protrusion and depression along the [001] direction. This feature is fully consistent with the previous result that it adsorbs on the short-bridge site with the C-O axis tilted along the [001] direction. The axis was induced to flip back and forth by vibrational excitations with the STM. Two configurations were observed for formaldehyde, whose structures were proposed based on their characteristic images and motions.

  1. S182 and STM2 gene missense mutations in sporadic alzheimer disease

    Energy Technology Data Exchange (ETDEWEB)

    Higuchi, Susumu; Matsushita, Sachio; Hasegawa, Yoshio; Muramatsu, Taro [Kurihama National Hospital, Yokosuka (Japan)] [and others

    1996-07-26

    The linkage of genes S182 and STM2 to early-onset or late-onset sporadic Alzheimer disease (AD) was not found in a group of 97 clinically-diagnosed AD patients and 46 autopsy-confirmed AD cases, using PCR-RFLP methods. 7 refs.

  2. Adaptation of Acoustic Model Experiments of STM via Smartphones and Tablets

    Science.gov (United States)

    Thees, Michael; Hochberg, Katrin; Kuhn, Jochen; Aeschlimann, Martin

    2017-01-01

    The importance of Scanning Tunneling Microscopy (STM) in today's research and industry leads to the question of how to include such a key technology in physics education. Manfred Euler has developed an acoustic model experiment to illustrate the fundamental measuring principles based on an analogy between quantum mechanics and acoustics. Based on…

  3. The combinatorial effect of different Equex STM paste concentrations, cryoprotectants and the straw-freezing methods on the post-thaw boar semen quality.

    Science.gov (United States)

    Wu, T-W; Cheng, F-P; Chen, I-H; Yang, C-H; Tsai, M-Y; Chang, M-H; Wang, J-H; Wu, J-T

    2013-02-01

    This study was to evaluate the combinatorial effect (14 treatments, A-N) of different Equex STM paste concentrations, cryoprotectants and the straw-freezing method on the post-thaw boar semen quality. Two ejaculates were collected from each of nine boars (three boars from each of three breeds). Semen was diluted in extenders with different concentrations of Equex STM paste and different cryoprotectants [glycerol or dimethylacetamide (DMA)] before cryopreserving via liquid nitrogen or dry ice. Motility, viability, percentage of spermatozoa with intense acrosomal staining and with normal morphology of post-thaw sperm were evaluated. The qualities of thawed semen were best preserved in treatment H (extender with 0.5% Equex STM paste and 5% glycerol and freezing by dry ice) and were worst in treatment B (extender with 0% Equex STM paste and 5% DMA and freezing by dry ice). Significant difference (p 0.05). Moreover, statistical analysis suggests that no significant difference was present in semen quality among breed or individual donors (p > 0.05). These findings suggest that Equex STM paste improved the cryosurvival efficiency of boar sperm, and the favourable straw-freezing method changes between glycerol and DMA. © 2012 Blackwell Verlag GmbH.

  4. Transition between scanning tunneling microscopy images of alkane derivatives on graphite

    International Nuclear Information System (INIS)

    Hibino, Masahiro; Tsuchiya, Hiroshi

    2015-01-01

    Graphical abstract: - Highlights: • SAMs of dialkyl sulfides form at the liquid–graphite interface. • STM contrast of molecules change reversibly between zigzag and aligned bright spot patterns. • The free energy for contrast change is smaller than the thermal energy (RT). • STM contrast change is caused by electronic effects and registry of the alkyl chains. - Abstract: Self-assembled monolayers of alkylated sulfides containing two alkyl chains and a sulfur atom positioned at the center of the molecules were studied on a graphite surface using scanning tunneling microscopy (STM). STM images of the closed-packed alkyl chains that extend linearly from the sulfur atoms change reversibly between a zigzag pattern and an aligned bright spot pattern on a time scale of minutes. The observation times of the zigzag and aligned bright spot patterns indicate that the difference between the free energies of these two stable molecular configurations with respect to the graphite surface is smaller than their thermal energies in the presence of a solvent, and 10 times smaller than the theoretical free energy between parallel and perpendicular configurations of the alkyl chains on graphite under vacuum. The change in the contrast of the STM images occurred owing to the electronic effects that depend on the registry of the alkyl chains on the graphite surface, and not by the classical observation of transfer between parallel and perpendicular orientations of alkyl chains on the surface.

  5. Dependence of electric field on STM tip preparation

    DEFF Research Database (Denmark)

    Huang, D.H.; Grey, Francois; Aono, M.

    1998-01-01

    Voltage pulses applied between an STM tip and a surface can modify the surface on the nanometer scale due to electric-field-induced evaporation. However, at present, different groups have achieved surface modification with quite different bias conditions, and it is still difficult to obtain high...... reproducibility in such experiments. In this paper, we measure the tip displacement during a pulse at constant tunnelling current, and deduce that the electric field produced by the pulse depends in a systematic way on tip preparation, The results show how differences in tip preparation can be a major source...

  6. The Influence Word of Mouth (Wom) on Revisit Intention: the Mediating Role of Destination Image (Case Study on Domestic Tourists Visiting Mount Bromo)

    OpenAIRE

    Ayuningtiyas, Galuh Ajeng; Nimran, Umar; Hamid, Djamhur

    2014-01-01

    The purpose of this research is to study the influence of Word of Mouth (WOM), on Revisit Intention with the intervening effect of Destination Image. 100 questionnaires were distributed to tourists who come to Mount Bromo through convenience sampling approach. The scales of measurement used in this study is Likert scale. Validity and Reliability of the measurement scale were established with the formula analysis correlation Product Moment Pearson and Cronbach's Alpha. The technique of data an...

  7. XPS/STM study of model bimetallic Pd–Au/HOPG catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Bukhtiyarov, Andrey V., E-mail: avb@catalysis.ru [Boreskov Institute of Catalysis, Lavrentieva Ave. 5, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation); Prosvirin, Igor P., E-mail: prosvirin@catalysis.ru [Boreskov Institute of Catalysis, Lavrentieva Ave. 5, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation); Bukhtiyarov, Valerii I., E-mail: vib@catalysis.ru [Boreskov Institute of Catalysis, Lavrentieva Ave. 5, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation)

    2016-03-30

    Graphical abstract: - Highlights: • The model Pd–Au/HOPG catalysts preparation has been studied by XPS and STM. • Model “core–shell” type Pd–Au/HOPG catalysts with different Pd/Au ratios were prepared. • Heating of the “core–shell” Pd–Au/HOPG samples up to 400 °C leads to alloy formation. • Contribution of parameters controlling the properties of Pd–Au alloyed particles has been discussed. - Abstract: The preparation of model bimetallic Pd–Au/HOPG catalysts has been investigated using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) techniques. Initially, model “core–shell” type Pd–Au/HOPG catalysts with similar particle size distribution (5–8 nm), but with different densities of particle locations on the HOPG surface and Pd/Au atomic ratios are prepared. Further, their thermal stability is studied within a temperature range of 50–500 °C at UHV conditions. It has been shown that annealing the model catalysts at a temperature range of 300–400 °C leads to formation of Pd–Au alloyed particles. Enhancement of heating temperature up to 500 °C results in sintering of bimetallic nanoparticles. Contribution of different parameters controlling the properties of Pd–Au alloyed particles has been discussed.

  8. Investigation of broken symmetry of Sb/Cu(111) surface alloys by VT-STM

    CSIR Research Space (South Africa)

    Ndlovu, GF

    2011-07-01

    Full Text Available This work present an in situ Variable Temperature Scanning Tunneling Microscopy (VT-STM) study of the Sb/Cu(111) system studied at various temperatures. The experimental data support a structural model in which Sb atoms displace up to 1...

  9. Fabrication of tuning-fork based AFM and STM tungsten probe

    KAUST Repository

    Al-Falih, Hisham

    2011-12-01

    We compare the sharpness of tungsten probe tips produced by the single-step and two-step dynamic electrochemical etching processes. A small radius of curvature (RoC) of 25 nm or less was routinely obtained when the two-step electrochemical etching (TEE) process was adopted, while the smallest achievable RoC was ∼10 nm, rendering it suitable for atomic force microscopy (AFM) or scanning tunneling microscopy (STM) applications. © 2011 IEEE.

  10. Dissociative and molecular oxygen chemisorption channels on reduced rutile TiO2(110): A high-resolution STM study

    DEFF Research Database (Denmark)

    Lira, Estephania; Hansen, Jonas Ørbæk; Huo, Peipei

    2010-01-01

    High-resolution scanning tunneling microscopy (STM) and temperature-programmed desorption (TPD) were used to study the interaction of O2 with reduced TiO2(110)–(1 × 1) crystals. STM is the technique of choice to unravel the relation between vacancy and non-vacancy assisted O2 dissociation channel...... in the near-surface region of reduced TiO2(110) crystals, the kinetics of the two O2 dissociation channels as well as the kinetics of the diffusion and reaction of Ti interstitials....

  11. Imaging and manipulation of a polar molecule on Ag(111)

    DEFF Research Database (Denmark)

    Lin, R.; Braun, K.F.; Tang, H.

    2001-01-01

    A scanning tunneling microscope (STM) was applied to image and laterally manipulate isolated phosphangulene molecules on Ag(111) at 6 K. Atomic-resolution images clearly revealed three characteristic types of appearances (three-lobed, fish and bump shape) for the adsorbed molecules, which could...

  12. STM-Induced Hydrogen Desorption via a Hole Resonance

    DEFF Research Database (Denmark)

    Stokbro, Kurt; Thirstrup, C.; Sakurai, M.

    1998-01-01

    We report STM-induced desorption of H from Si(100)-H(2 X 1) at negative sample bias. The desorption rate exhibits a power-law dependence on current and a maximum desorption rate at -7 V. The desorption is explained by vibrational heating of H due to inelastic scattering of tunneling holes...... with the Si-H 5 sigma hole resonance. The dependence of desorption rate on current and bias is analyzed using a novel approach for calculating inelastic scattering, which includes the effect of the electric field between tip and sample. We show that the maximum desorption rate at -7 V is due to a maximum...

  13. The Impact of Pointing on the Short-Term Memory (STM) of Heterophonic Homographs

    Science.gov (United States)

    Vaknin-Nusbaum, Vered; Miller, Paul

    2014-01-01

    This study entailed two short-term memory (STM) experiments investigating the importance of vowel diacritics for the temporary retention of three distinct Hebrew word list types: heterophonic homographs, non-homographs and homophonic homographs. Eighty university students participated in each experiment, with half of them tested with word lists…

  14. Whey protein isolate improves acid and bile tolerances of Streptococcus thermophilus ST-M5 and Lactobacillus delbrueckii ssp. bulgaricus LB-12.

    Science.gov (United States)

    Vargas, Luis A; Olson, Douglas W; Aryana, Kayanush J

    2015-04-01

    Acid tolerance and bile tolerance are important probiotic characteristics. Whey proteins contain branched-chain amino acids, which play a role in muscle building and are popular among athletes. Increasing emphasis is being placed on diets containing less carbohydrate, less fat, and more protein. The effect of incremental additions of whey protein isolate (WPI) on probiotic characteristics of pure cultures is not known. The objective of this study was to determine the influence of added WPI on acid tolerance and bile tolerance of pure cultures of Streptococcus thermophilus ST-M5 and Lactobacillus bulgaricus LB-12. The WPI was used at 0 (control), 1, 2 and 3% (wt/vol). Assessment of acid tolerance was conducted on pure cultures at 30-min intervals for 2h of acid exposure and bile tolerance at 1-h intervals for 5h of bile exposure. Use of 1, 2, and 3% WPI improved acid tolerance of Strep. thermophilus ST-M5 and Lb. bulgaricus LB-12. The highest counts for acid tolerance of Strep. thermophilus ST-M5 and Lb. bulgaricus LB-12 were obtained when 3% WPI was used. Use of 2 and 3% WPI improved bile tolerance of Strep. thermophilus ST-M5 and Lb. bulgaricus LB-12 over 5h of bile exposure. The use of WPI is recommended to improve acid and bile tolerance of the yogurt culture bacteria Strep. thermophilus ST-M5 and Lb. bulgaricus LB-12. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  15. Control by hardware of government systems for laser diodes with STM32F4 and Peltier cells

    International Nuclear Information System (INIS)

    Ulloa Solano, Natalia Irina

    2013-01-01

    A low cost prototype of a government system is developed for laser diodes with STM32F4 microcontrollers and Peltier cooling. Commercial and homemade government system (with STM32F4 microcontrollers ) are investigated with the objective of adequately control the current of a laser diode. Characteristics of STM32F4 microcontrollers are described. The low cost platforms as the Arduino and Raspberry Pi are compared. A bibliographical and documentary compilation is realized for the preliminary study of the components and tools to use in the prototype. The theory related with the heat transfer between a laser diode and the outside, and a Peltier cell and outside is summarized. A heat dissipation model is proposed of a system formed by a laser diode and Peltier cell. A control system of current and fed back temperature is designed and implemented to allow adequately control laser diodes without and with photodiode (2 pickups and 3 pickups respectively). The viability of control with free software is studied and corroborated. The temperature control of the laser diode using a Peltier cell as cooler has been possible through a simple control of ON/OFF mode. The integration of devices such as ADC, DAC, timers and facilities of STM32F4 microcontroller, have allowed to optimize costs by hardware, save time and costs. Also, the incorporation of the Cortex-M4 processor has optimized the consumption of operational resources and has executed much of its instruction set of efficient way. Because of this, the project has complied with its maximum as to low cost is concerned [es

  16. A high-stability scanning tunneling microscope achieved by an isolated tiny scanner with low voltage imaging capability

    Science.gov (United States)

    Wang, Qi; Hou, Yubin; Wang, Junting; Lu, Qingyou

    2013-11-01

    We present a novel homebuilt scanning tunneling microscope (STM) with high quality atomic resolution. It is equipped with a small but powerful GeckoDrive piezoelectric motor which drives a miniature and detachable scanning part to implement coarse approach. The scanning part is a tiny piezoelectric tube scanner (industry type: PZT-8, whose d31 coefficient is one of the lowest) housed in a slightly bigger polished sapphire tube, which is riding on and spring clamped against the knife edges of a tungsten slot. The STM so constructed shows low back-lashing and drifting and high repeatability and immunity to external vibrations. These are confirmed by its low imaging voltages, low distortions in the spiral scanned images, and high atomic resolution quality even when the STM is placed on the ground of the fifth floor without any external or internal vibration isolation devices.

  17. A high-stability scanning tunneling microscope achieved by an isolated tiny scanner with low voltage imaging capability

    International Nuclear Information System (INIS)

    Wang, Qi; Wang, Junting; Lu, Qingyou; Hou, Yubin

    2013-01-01

    We present a novel homebuilt scanning tunneling microscope (STM) with high quality atomic resolution. It is equipped with a small but powerful GeckoDrive piezoelectric motor which drives a miniature and detachable scanning part to implement coarse approach. The scanning part is a tiny piezoelectric tube scanner (industry type: PZT-8, whose d 31 coefficient is one of the lowest) housed in a slightly bigger polished sapphire tube, which is riding on and spring clamped against the knife edges of a tungsten slot. The STM so constructed shows low back-lashing and drifting and high repeatability and immunity to external vibrations. These are confirmed by its low imaging voltages, low distortions in the spiral scanned images, and high atomic resolution quality even when the STM is placed on the ground of the fifth floor without any external or internal vibration isolation devices

  18. A high-stability scanning tunneling microscope achieved by an isolated tiny scanner with low voltage imaging capability.

    Science.gov (United States)

    Wang, Qi; Hou, Yubin; Wang, Junting; Lu, Qingyou

    2013-11-01

    We present a novel homebuilt scanning tunneling microscope (STM) with high quality atomic resolution. It is equipped with a small but powerful GeckoDrive piezoelectric motor which drives a miniature and detachable scanning part to implement coarse approach. The scanning part is a tiny piezoelectric tube scanner (industry type: PZT-8, whose d31 coefficient is one of the lowest) housed in a slightly bigger polished sapphire tube, which is riding on and spring clamped against the knife edges of a tungsten slot. The STM so constructed shows low back-lashing and drifting and high repeatability and immunity to external vibrations. These are confirmed by its low imaging voltages, low distortions in the spiral scanned images, and high atomic resolution quality even when the STM is placed on the ground of the fifth floor without any external or internal vibration isolation devices.

  19. Ethylene dissociation on flat and stepped Ni(111): A combined STM and DFT study

    DEFF Research Database (Denmark)

    Vang, R.T.; Honkala, Johanna Karoliina; Dahl, S.

    2006-01-01

    The dissociative adsorption of ethylene (C(2)H(4)) on Ni(111) was studied by scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. The STM studies reveal that ethylene decomposes exclusively at the step edges at room temperature. However, the step edge sites...... are poisoned by the reaction products and thus only a small brim of decomposed ethylene is formed. At 500 K decomposition on the (111) facets leads to a continuous growth of carbidic islands, which nucleate along the step edges. DFT calculations were performed for several intermediate steps...... in the decomposition of ethylene on both Ni(111) and the stepped Ni(211) surface. In general the Ni(211) surface is found to have a higher reactivity than the Ni(111) surface. Furthermore, the calculations show that the influence of step edge atoms is very different for the different reaction pathways. In particular...

  20. Novel response function resolves by image deconvolution more details of surface nanomorphology

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    2010-01-01

    and to imaging by in situ STM of electrocrystallization of copper on gold in electrolytes containing copper sulfate and sulfuric acid. It is suggested that the observed peaks of the recorded image do not represent atoms, but the atomic structure may be recovered by image deconvolution followed by calibration...

  1. Ab initio simulations of scanning-tunneling-microscope images with embedding techniques and application to C58-dimers on Au(111).

    Science.gov (United States)

    Wilhelm, Jan; Walz, Michael; Stendel, Melanie; Bagrets, Alexei; Evers, Ferdinand

    2013-05-14

    We present a modification of the standard electron transport methodology based on the (non-equilibrium) Green's function formalism to efficiently simulate STM-images. The novel feature of this method is that it employs an effective embedding technique that allows us to extrapolate properties of metal substrates with adsorbed molecules from quantum-chemical cluster calculations. To illustrate the potential of this approach, we present an application to STM-images of C58-dimers immobilized on Au(111)-surfaces that is motivated by recent experiments.

  2. Investigation of lateral forces in dynamic mode using combined AFM/STM

    OpenAIRE

    Atabak, Mehrdad

    2007-01-01

    Ankara : The Department of Physics and The Institute of Engineering and Science of Bilkent University, 2007. Thesis (Ph.D.) -- Bilkent University, 2007. Includes bibliographical references leaves 114-126. In this Ph.D. work, we constructed a ¯ber optic interferometer based non-contact Atomic Force Microscope (nc-AFM) combined with Scanning Tunneling Micro- scope(STM) to study lateral force interactions on Si(111)-(77) surface. The in- terferometer has been built in such a wa...

  3. Fabrication of Silicon nanostructures by UHV-STM lithography in Self-Assembled Monolayers

    International Nuclear Information System (INIS)

    Sundermann, M.; Brechling, A.; Rott, K.; Meyners, D.; Kleineberg, U.; Heinzmann, U.; Knueller, A.; Eck, W.; Goelzhueuser, A.; Grunze, M.

    2002-01-01

    Our approach utilizes UHV-STM writing in Self-Assembled Monolayers (SAM). SAMs form highly-ordered ultrathin (∼2-3 nm) monomolecular layers on top of pre-activated Si(100) or Si(111) surfaces. After patterning by UHV-STM writing in constant-current mode at different write parameters (gap voltage, electron dose) the modified Self-Assembled Monolayer serves as an etch mask for an anisotropic wet etch transfer (two-step etch process in aqueous solutions of 5 % HF and 1 M KOH), of the write structure into the silicon substrate. The corresponding silicon nano-structures have been analyzed afterwards by AFM or SEM to characterize the pattern accuracy. We have studied the suitability of three different types of SAMs on silicon single-crystals. Alkyl-chain-type SAMs like Octadecylsilane (ODS) monolayer have been formed by immersion of hydroxylated Si(100) in Octadecyltrichlorosilane (CH 3 (CH 27 SiCl 3 ) while SAMs with aromatic spacer groups such as Hydroxybiphenyl (HBP, (C 6 H 6 ) 2 OH) and Ethoxybiphenyl silane (EBP, (C 6 H 6 ) 2 O(CH 2 ) 3 Si(OCH 3 ) 3 ) are formed on Si(111). (Authors)

  4. Recoding between two types of STM representation revealed by the dynamics of memory search

    NARCIS (Netherlands)

    Leszczyński, Marcin; Myers, Nicolas E.; Akyürek, Elkan G.; Schubö, Anna

    Visual STM (VSTM) is thought to be related to visual attention in several ways. Attention controls access to VSTM during memory encoding and plays a role in the maintenance of stored information by strengthening memorized content. We investigated the involvement of visual attention in recall from

  5. Hydrogen absorption in epitaxial Nb-films. A STM-study; Wasserstoffabsorption in epitaktischen Niobschichten. Eine STM-Studie

    Energy Technology Data Exchange (ETDEWEB)

    Noerthemann, K.

    2006-07-01

    In this work the phase transition of the system Niobium Hydrogen in thin films was investigated. The epitaxial Niobium films were fabricated using ion sputtering on sapphire substrates. The changes due to the hydrogen loading were observed with the scanning tunnel microscope (STM). With this method it is possible to detect the changes in the nanometer scale. With help of theoretical models it was possible to establish volume changes through the measured surface data. This is possible due to the linear relationship between hydrogen concentration and volume expansion. Comparisons between experimental data and calculations, which were done using the 'finite element method', allows to establish that the hydride precipitates are of cylindrical form. Thereafter the time continuously measurements of nuclei formation and precipitations growth was investigated. The growth is described through a 'Johnson-Mehl-Avrami' kinetic. Whereas coherent precipitations at first stage were observed, afterwards at higher Hydrogen concentration these transformed to incoherent. This coherent - incoherent transition occur at precipitation sizes which shows a film thickness dependency. (orig.)

  6. XPS and STM study of the growth and structure of passive films in high temperature water on a nickel-base alloy

    Energy Technology Data Exchange (ETDEWEB)

    Machet, A.; Galtayries, A.; Zanna, S.; Klein, L.; Maurice, V.; Jolivet, P.; Foucault, M.; Combrade, P.; Scott, P.; Marcus, P

    2004-09-15

    The early stages of passivation in high temperature water of a nickel-chromium-iron alloy (Alloy 600) have been investigated by X-ray Photoelectron Spectroscopy (XPS) and Scanning Tunneling Microscopy (STM). The samples (polycrystal Ni-16Cr-9Fe (wt. %) and single crystal Ni-17Cr-7Fe (1 1 1)) have been exposed for short time periods (0.4-8.2 min) to high temperature (325 deg. C) and high pressure water, under controlled hydrogen pressure, in a microautoclave designed to transfer the samples from and to the XPS spectrometer without air exposure. In the early stages of oxidation of the alloy (0.4-4 min), an ultra-thin oxide layer (about 1 nm) is formed, which consists of chromium oxide (Cr{sub 2}O{sub 3}), according to the Cr 2p{sub 3/2} core level spectrum. An outer layer of Cr(OH){sub 3} with a very small amount of Ni(OH){sub 2} is also revealed by the Cr 2p{sub 3/2}, Ni 2p{sub 3/2}, and O 1s core level spectra. At this early stage, there is a temporary blocking of the growth of Cr{sub 2}O{sub 3}. For longer exposures (4-8 min), the Cr{sub 2}O{sub 3} inner layer becomes thicker, at the expense of the outer Cr(OH){sub 3} layer. This implies the transport of Cr and Ni through the oxide layer, and release of Ni{sup 2+} in the solution. The structure of the ultra-thin oxide film formed on a single crystal Ni-17Cr-7Fe(1 1 1) alloy was analysed by STM in the constant current mode; STM images reveal that, in the early stages of oxidation, the oxide is crystalline, and the observed structure is consistent with the hexagonal structure of the oxygen sub-lattice in the basal plane (0 0 0 1) of {alpha}-Cr{sub 2}O{sub 3}.

  7. Self-assembly, Dynamics and Chirality of Conformational Switches on Metal Surfaces Studied by UHV-STM

    DEFF Research Database (Denmark)

    Nuermaimaiti, Ajiguli

    2013-01-01

    structures formed by the conformational switches and statistical analysis of conformational states, a detailed study of dynamic processes is performed by acquiring time-resolved STM data. Furthermore, one of the possible applications of conformational switches towards inducing chirality in surface assemblies...

  8. In situ STM imaging and direct electrochemistry of Pyrococcus furiosus ferredoxin assembled on thiolate-modified Au(111) surfaces

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Christensen, Hans Erik Mølager; Ooi, Bee Lean

    2004-01-01

    We have addressed here electron transfer (ET) of Pyrococcus furiosus ferredoxin (PfFd, 7.5 kDa) in both homogeneous solution using edge plane graphite (EPG) electrodes and in the adsorbed state by electrochemistry on surface-modified single-crystal Au(111) electrodes, This has been supported...... by surface microscopic structures of PfFd monolayers, as revealed by scanning tunneling microscopy under potential control (in situ STM). Direct ET between PfFd in phosphate buffer solution, pH 7.9, and EPG electrodes is observed in the presence of promoters. Neomycin gives rise to a pair of redox peaks...... with a formal potential of ca -430 mV (vs SCE), corresponding to [3Fe-4S](1+/0). The presence of an additional promoter, which can be propionic acid, alanine, or cysteine, induces a second pair of redox peaks at similar to-900 mV (vs SCE) arising from [3Fe-4S](0/1-). A robust neomycin-PfFd complex was detected...

  9. Atomic origin of the scanning tunneling microscopy images of charge-density-waves on 1T-TaSe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Stoltz, D. [Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden (Netherlands)], E-mail: stoltz@physics.leidenuniv.nl; Bielmann, M.; Schlapbach, L. [Swiss Federal Lab for Materials Science and Technology (EMPA), CH-8600 Duebendorf (Switzerland); Bovet, M. [Institut de Physique, Universite de Neuchatel, CH-2000 Neuchatel (Switzerland); Berger, H. [Institut de Physique Appliquee, EPF, 1015 Lausanne (Switzerland); Goethelid, M. [Materialfysik, MAP, KTH-Electrum, SE-16440 Kista (Sweden); Stoltz, S.E. [MAX-Lab, Lund University, SE-22100 Lund (Sweden); Starnberg, H.I. [Department of Physics, Goeteborg University and Chalmers University of Technology, SE-412 96 Goeteborg (Sweden)

    2008-07-01

    We show atomically resolved scanning tunneling microscopy (STM) images of charge density waves (CDWs) at room temperature together with angle-resolved photoelectron band-mapping of 1T-TaSe{sub 2}. By comparing the results of these two techniques, we demonstrate the atomic structure of the CDW-features observed by the STM and atomic origin of the reconstructed band-structure in this material.

  10. An analytic algorithm for global coverage of the revisiting orbit and its application to the CFOSAT satellite

    Science.gov (United States)

    Xu, Ming; Huang, Li

    2014-08-01

    This paper addresses a new analytic algorithm for global coverage of the revisiting orbit and its application to the mission revisiting the Earth within long periods of time, such as Chinese-French Oceanic Satellite (abbr., CFOSAT). In the first, it is presented that the traditional design methodology of the revisiting orbit for some imaging satellites only on the single (ascending or descending) pass, and the repeating orbit is employed to perform the global coverage within short periods of time. However, the selection of the repeating orbit is essentially to yield the suboptimum from the rare measure of rational numbers of passes per day, which will lose lots of available revisiting orbits. Thus, an innovative design scheme is proposed to check both rational and irrational passes per day to acquire the relationship between the coverage percentage and the altitude. To improve the traditional imaging only on the single pass, the proposed algorithm is mapping every pass into its ascending and descending nodes on the specified latitude circle, and then is accumulating the projected width on the circle by the field of view of the satellite. The ergodic geometry of coverage percentage produced from the algorithm is affecting the final scheme, such as the optimal one owning the largest percentage, and the balance one possessing the less gradient in its vicinity, and is guiding to heuristic design for the station-keeping control strategies. The application of CFOSAT validates the feasibility of the algorithm.

  11. eWOM, Revisit Intention, Destination Trust and Gender

    OpenAIRE

    Abubakar, Abubakar Mohammed; Ilkan, Mustafa; Al-Tal, Raad Meshall; Eluwole, Kayode

    2017-01-01

    This article investigates the impact of eWOM on intention to revisit and destination trust, and the moderating role of gender in medical tourism industry. Result from structural equation modeling (n=240) suggests the following: (1) that eWOM influences intention to revisit and destination trust; (2) that destination trust influences intention to revisit; (3) that the impact of eWOM on intention to revisit is about 1.3 times higher in men; (4) that the impact of eWOM on destination trust is ab...

  12. Recoding between Two Types of STM Representation Revealed by the Dynamics of Memory Search

    Science.gov (United States)

    Leszczynski, Marcin; Myers, Nicholas E.; Akyurek, Elkan G.; Schubo, Anna

    2012-01-01

    Visual STM (VSTM) is thought to be related to visual attention in several ways. Attention controls access to VSTM during memory encoding and plays a role in the maintenance of stored information by strengthening memorized content. We investigated the involvement of visual attention in recall from VSTM. In two experiments, we measured…

  13. Living on the edge : STM studies of the creation, diffusion and annihilation of surface vacancies

    NARCIS (Netherlands)

    Schoots, Koen

    2007-01-01

    This thesis describes an STM study of the creation, diffusion and annihilation of missing atoms, so-called surface vacancies, in the Cu(100) surface. Because of the extremely high mobility of surface vacancies in combination with their extremely low density, we have been forced to use tracer

  14. In-Situ TEM-STM Observations of SWCNT Ropes/Tubular Transformations

    Science.gov (United States)

    Sola, F.; Lebron-Colon, M.; Ferreira, P. J.; Fonseca, L. F.; Meador, M. A.; Marin, C.

    2010-01-01

    Single-walled carbon nanotubes (SWCNTs) prepared by the HiPco process were purified using a modified gas phase purification technique. A TEM-STM holder was used to study the morphological changes of SWCNT ropes as a function of applied voltage. Kink formation, buckling behavior, tubular transformation and eventual breakdown of the system were observed. The tubular formation was attributed to a transformation from SWCNT ropes to multi-walled carbon nanotube (MWCNT) structures. It is likely mediated by the patching and tearing mechanism which is promoted primarily by the mobile vacancies generated due to current-induced heating and, to some extent, by electron irradiation.

  15. Multiple frequency ECH (MFECH) in SM-1 and STM-1

    International Nuclear Information System (INIS)

    Lazar, N.; Barter, J.; Dandl, R.; DiVergilio, W.; Quon, B.; Wuerker, R.

    1982-01-01

    Plasma properties were studied in a simple mirror (SM-1) and a five-cell axisymmetric tandem mirror (STM-1) using multiple frequency ECH. The cold plasma properties depend predominantly on total power but the efficiency for producing the diamagnetic ring plasma depends critically on heating with multiple frequencies. The effects of frequency separation of the heating sources will be demonstrated. Noise fluctuations in the axial current are suppressed with increasing ring-β, but the observed frequency spectrum are not well understood. Annulus β in the multiple mirror is also dependent on MFECH. Plans for and experiments in the new facility will be described

  16. Imaging by in situ Scanning Tunnelling Microscopy and its Nanotechnological Perspectives

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    2002-01-01

    of the tip and working electrode. In collaboration with Danish Micro Engineering A/S, the instrument was constructed and tested in laboratory environments. The system was successfully developed, as to meet international-market requirements. Within the frame of the work, procedures of tip coating...... of simultaneous imaging and electrochemical manipulation offers unprecedented possibilities of device construction at the nanometer level. The present work is therefore intended as a promotion of in situ STM as a tool of nanotechnology that allows device fabrication of sub-nanometer tolerances. Novel applications......-biotechnology are evaluated. It is thus documented that in situ STM constitutes an indispensable tool of nanotechnology. Keywords are imaging and control. The manufacture of nanotechnological devices is exemplified by construction of a ‘nanotypewriter’ that exploits a novel feature of electrochemistry. The nanotypewriter...

  17. Deducing 2D crystal structure at the liquid/solid interface with atomic resolution: a combined STM and SFG study.

    Science.gov (United States)

    McClelland, Arthur A; Ahn, Seokhoon; Matzger, Adam J; Chen, Zhan

    2009-11-17

    Sum frequency generation vibrational spectroscopy (SFG) has been applied to study two-dimensional (2D) crystals formed by an isophthalic acid diester on the surface of highly oriented pyrolytic graphite, providing complementary measurements to scanning tunneling microscopy (STM) and computational modeling. SFG results indicate that both aromatic and C=O groups in the 2D crystal tilt from the surface. This study demonstrates that a combination of SFG and STM techniques can be used to gain a more complete picture of 2D crystal structure, and it is necessary to consider solvent-2D crystal interactions and dynamics in the computer models to achieve an accurate representation of interfacial structure.

  18. Preparation of Atomically Flat Si(111)-H Surfaces in Aqueous Ammonium Fluoride Solutions Investigated by Using Electrochemical, In Situ EC-STM and ATR-FTIR Spectroscopic Methods

    International Nuclear Information System (INIS)

    Bae, Sang Eun; Oh, Mi Kyung; Min, Nam Ki; Paek, Se Hwan; Hong, Suk In; Lee, Chi-Woo J.

    2004-01-01

    Electrochemical, in situ electrochemical scanning tunneling microscope (EC-STM), and attenuated total reflectance-FTIR (ATR-FTIR) spectroscopic methods were employed to investigate the preparation of atomically flat Si(111)-H surface in ammonium fluoride solutions. Electrochemical properties of atomically flat Si(111)-H surface were characterized by anodic oxidation and cathodic hydrogen evolution with the open circuit potential (OCP) of ca. .0.4 V in concentrated ammonium fluoride solutions. As soon as the natural oxide-covered Si(111) electrode was immersed in fluoride solutions, OCP quickly shifted to near .1 V, which was more negative than the flat band potential of silicon surface, indicating that the surface silicon oxide had to be dissolved into the solution. OCP changed to become less negative as the oxide layer was being removed from the silicon surface. In situ EC-STM data showed that the surface was changed from the initial oxide covered silicon to atomically rough hydrogen-terminated surface and then to atomically flat hydrogen terminated surface as the OCP moved toward less negative potentials. The atomically flat Si(111)-H structure was confirmed by in situ EC-STM and ATR-FTIR data. The dependence of atomically flat Si(111)-H terrace on mis-cut angle was investigated by STM, and the results agreed with those anticipated by calculation. Further, the stability of Si(111)-H was checked by STM in ambient laboratory conditions

  19. Enhanced resolution imaging of ultrathin ZnO layers on Ag(111) by multiple hydrogen molecules in a scanning tunneling microscope junction

    Science.gov (United States)

    Liu, Shuyi; Shiotari, Akitoshi; Baugh, Delroy; Wolf, Martin; Kumagai, Takashi

    2018-05-01

    Molecular hydrogen in a scanning tunneling microscope (STM) junction has been found to enhance the lateral spatial resolution of the STM imaging, referred to as scanning tunneling hydrogen microscopy (STHM). Here we report atomic resolution imaging of 2- and 3-monolayer (ML) thick ZnO layers epitaxially grown on Ag(111) using STHM. The enhanced resolution can be obtained at a relatively large tip to surface distance and resolves a more defective structure exhibiting dislocation defects for 3-ML-thick ZnO than for 2 ML. In order to elucidate the enhanced imaging mechanism, the electric and mechanical properties of the hydrogen molecular junction (HMJ) are investigated by a combination of STM and atomic force microscopy. It is found that the HMJ shows multiple kinklike features in the tip to surface distance dependence of the conductance and frequency shift curves, which are absent in a hydrogen-free junction. Based on a simple modeling, we propose that the junction contains several hydrogen molecules and sequential squeezing of the molecules out of the junction results in the kinklike features in the conductance and frequency shift curves. The model also qualitatively reproduces the enhanced resolution image of the ZnO films.

  20. An ultrahigh vacuum fast-scanning and variable temperature scanning tunneling microscope for large scale imaging.

    Science.gov (United States)

    Diaconescu, Bogdan; Nenchev, Georgi; de la Figuera, Juan; Pohl, Karsten

    2007-10-01

    We describe the design and performance of a fast-scanning, variable temperature scanning tunneling microscope (STM) operating from 80 to 700 K in ultrahigh vacuum (UHV), which routinely achieves large scale atomically resolved imaging of compact metallic surfaces. An efficient in-vacuum vibration isolation and cryogenic system allows for no external vibration isolation of the UHV chamber. The design of the sample holder and STM head permits imaging of the same nanometer-size area of the sample before and after sample preparation outside the STM base. Refractory metal samples are frequently annealed up to 2000 K and their cooldown time from room temperature to 80 K is 15 min. The vertical resolution of the instrument was found to be about 2 pm at room temperature. The coarse motor design allows both translation and rotation of the scanner tube. The total scanning area is about 8 x 8 microm(2). The sample temperature can be adjusted by a few tens of degrees while scanning over the same sample area.

  1. Apparent Barrier Height in Scanning Tunneling Microscopy Revisited

    DEFF Research Database (Denmark)

    Olesen, L.; Brandbyge, Mads; Sørensen, Mads Reinholdt

    1996-01-01

    The apparent barrier height phi(ap), that is, the rate of change of the logarithm of the conductance with tip-sample separation in a scanning tunneling microscope (STM), has been measured for Ni, Pt, and Au single crystal surfaces. The results show that phi(ap) is constant until point contact...... is reached rather than decreasing at small tunneling gap distances, as previously reported. The findings for phi(ap) can be accounted for theoretically by including the relaxations of the tip-surface junction in an STM due to the strong adhesive forces at close proximity. These relaxation effects are shown...

  2. Imaging Anyons with Scanning Tunneling Microscopy

    Science.gov (United States)

    Papić, Zlatko; Mong, Roger S. K.; Yazdani, Ali; Zaletel, Michael P.

    2018-01-01

    Anyons are exotic quasiparticles with fractional charge that can emerge as fundamental excitations of strongly interacting topological quantum phases of matter. Unlike ordinary fermions and bosons, they may obey non-Abelian statistics—a property that would help realize fault-tolerant quantum computation. Non-Abelian anyons have long been predicted to occur in the fractional quantum Hall (FQH) phases that form in two-dimensional electron gases in the presence of a large magnetic field, such as the ν =5 /2 FQH state. However, direct experimental evidence of anyons and tests that can distinguish between Abelian and non-Abelian quantum ground states with such excitations have remained elusive. Here, we propose a new experimental approach to directly visualize the structure of interacting electronic states of FQH states with the STM. Our theoretical calculations show how spectroscopy mapping with the STM near individual impurity defects can be used to image fractional statistics in FQH states, identifying unique signatures in such measurements that can distinguish different proposed ground states. The presence of locally trapped anyons should leave distinct signatures in STM spectroscopic maps, and enables a new approach to directly detect—and perhaps ultimately manipulate—these exotic quasiparticles.

  3. Josephson current at atomic scale: Tunneling and nanocontacts using a STM

    International Nuclear Information System (INIS)

    Rodrigo, J.G.; Crespo, V.; Vieira, S.

    2006-01-01

    Using a scanning tunneling microscope, STM, with a superconducting tip, we have measured the Josephson current in atomic size tunnel junctions and contacts with a small number of quantum channels of conduction. We analyze our results in terms of the Ivanchenko and Zil'berman model for phase diffusion. The effect of the thermal energy and the electromagnetic environment on the Josephson current is discussed in terms of the transmissions of the individual quantum channels. These results suppose an initial step to the control of Scanning Josephson Spectroscopy at atomic level

  4. Programmable set-up for electrochemical preparation of STM tips and ultra-sharp field emission cathodes

    Czech Academy of Sciences Publication Activity Database

    Knápek, Alexandr; Sýkora, Jiří; Chlumská, Jana; Sobola, D.

    2017-01-01

    Roč. 173, APR 5 (2017), s. 42-47 ISSN 0167-9317 R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : field emission cathode * STM tip * electrochemical etching Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Chemical process engineering Impact factor: 1.806, year: 2016

  5. Revisiting Cross-Channel Information Transfer for Chromatic Aberration Correction

    KAUST Repository

    Sun, Tiancheng; Peng, Yifan; Heidrich, Wolfgang

    2017-01-01

    Image aberrations can cause severe degradation in image quality for consumer-level cameras, especially under the current tendency to reduce the complexity of lens designs in order to shrink the overall size of modules. In simplified optical designs, chromatic aberration can be one of the most significant causes for degraded image quality, and it can be quite difficult to remove in post-processing, since it results in strong blurs in at least some of the color channels. In this work, we revisit the pixel-wise similarity between different color channels of the image and accordingly propose a novel algorithm for correcting chromatic aberration based on this cross-channel correlation. In contrast to recent weak prior-based models, ours uses strong pixel-wise fitting and transfer, which lead to significant quality improvements for large chromatic aberrations. Experimental results on both synthetic and real world images captured by different optical systems demonstrate that the chromatic aberration can be significantly reduced using our approach.

  6. Revisiting Cross-Channel Information Transfer for Chromatic Aberration Correction

    KAUST Repository

    Sun, Tiancheng

    2017-12-25

    Image aberrations can cause severe degradation in image quality for consumer-level cameras, especially under the current tendency to reduce the complexity of lens designs in order to shrink the overall size of modules. In simplified optical designs, chromatic aberration can be one of the most significant causes for degraded image quality, and it can be quite difficult to remove in post-processing, since it results in strong blurs in at least some of the color channels. In this work, we revisit the pixel-wise similarity between different color channels of the image and accordingly propose a novel algorithm for correcting chromatic aberration based on this cross-channel correlation. In contrast to recent weak prior-based models, ours uses strong pixel-wise fitting and transfer, which lead to significant quality improvements for large chromatic aberrations. Experimental results on both synthetic and real world images captured by different optical systems demonstrate that the chromatic aberration can be significantly reduced using our approach.

  7. Theoretical studies of finite size effects and screening effects caused by a STM tip in Luettinger liquids

    International Nuclear Information System (INIS)

    Guigou, Marine

    2009-01-01

    This thesis takes place in the field of condensed matter. More precisely, we focus on the finite size effects and the screening effects caused by a STM tip in a quantum wire. For that, we use, first, the Luettinger liquid theory, which allows to describe strongly correlated systems and secondly, the Keldysh formalism, which is necessary to treat the out-of-equilibrium systems. For these studies, we consider, the currant, the noise and the conductance. The noise presents a non-Poissonian behaviour, when finite size effects appear. Through the photo-assisted transport, it is shown that those effects hide the effects of the Coulomb interactions. Considering the proximity between the STM tip, used as a probe or as an injector, and a quantum wire, screening effects appear. We can conclude that they play a similar role to those of Coulomb interactions. (author) [fr

  8. Adaptation of acoustic model experiments of STM via smartphones and tablets

    Science.gov (United States)

    Thees, Michael; Hochberg, Katrin; Kuhn, Jochen; Aeschlimann, Martin

    2017-10-01

    The importance of Scanning Tunneling Microscopy (STM) in today's research and industry leads to the question of how to include such a key technology in physics education. Manfred Euler has developed an acoustic model experiment to illustrate the fundamental measuring principles based on an analogy between quantum mechanics and acoustics. Based on earlier work we applied mobile devices such as smartphones and tablets instead of using a computer to record and display the experimental data and thus converted Euler's experimental setup into a low-cost experiment that is easy to build and handle by students themselves.

  9. Photoemission and STM, STS study of Cs/p-GaAs(110)

    International Nuclear Information System (INIS)

    Yamada, T.; Fujii, J.; Mizoguchi, T.

    2001-01-01

    Various stage of adsorbed Cs, i.e., one-dimensional (1D) lines, polygons and coherently c(4x4)-ordered polygons, on cleaved p-GaAs(110) are studied by scanning tunneling microscopy (STM) and scanning tunneling spectroscopies (STS) with an interest in relation to the photo-electron emission. It is understood that only the coherently c(4x4)-ordered Cs polygon surface (Cs coverage of 0.6 ML and 0.7 ML) can emit photo-electrons due to a sufficient reduction of the local work function down to 1.3 eV to get a negative electron affinity state

  10. Explaining tourists satisfaction and intention to revisit Nha Trang, Viet Nam

    OpenAIRE

    Tran, Thi Ai Cam

    2011-01-01

    The first purpose of the thesis is to find how visitors evaluate the quality of different facets or attributes of a destination image of Nha Trang, how satisfied they are with Nha Trang, loyalty intention to revisit and willingness to recommend Nha Trang to others. The second is to investigate what “image” is most important to explain global satisfaction with visiting Nha Trang. The third is to investigate how perceived quality, satisfaction and other motivational or dismotivational factors ...

  11. Analysis and Calibration of in situ scanning tunnelling microscopy Images with atomic Resolution Influenced by Surface Drift Phenomena

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Møller, Per

    1994-01-01

    The influence of surface drift velocities on in situ scanning tunnelling microscopy (STM) experiments with atomic resolution is analysed experimentally and mathematically. Constant drift velocities much smaller than the speed of scanning can in many in situ STM experiments with atomic resolution ...... as well as the vectors of the non-distorted surface lattice can be determined. The calibration of distances can thus be carried out also when the image is influenced by drift. Results with gold surfaces and graphite surfaces are analysed and discussed....

  12. Lakatos Revisited.

    Science.gov (United States)

    Court, Deborah

    1999-01-01

    Revisits and reviews Imre Lakatos' ideas on "Falsification and the Methodology of Scientific Research Programmes." Suggests that Lakatos' framework offers an insightful way of looking at the relationship between theory and research that is relevant not only for evaluating research programs in theoretical physics, but in the social…

  13. Hardware-Software Complex for Functional and Parametric Tests of ARM Microcontrollers STM32F1XX

    Directory of Open Access Journals (Sweden)

    Egorov Aleksey

    2016-01-01

    Full Text Available The article presents the hardware-software complex for functional and parametric tests of ARM microcontrollers STM32F1XX. The complex is based on PXI devices by National Instruments and LabVIEW software environment. Data exchange procedure between a microcontroller under test and the complex hardware is describes. Some test results are also presented.

  14. Covalently Immobilised Cytochrome C Imaged by In Situ Scanning Tunnelling Microscopy

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Olesen, Klaus G.; Danilov, Alexey I.

    1997-01-01

    In situ scanning tunnelling microscopy (STM) imaging of cytochrome c (cyt c) on polycrystalline Pt surfaces and on Au(lll) was achieved first by covalent immobilisation of 3-aminopropyltriethoxysilane (3-APTS) brought to react with oxide present on the Pt surfaces. Covalently bound 3-APTS forms...

  15. Oxidative phosphorylation revisited

    DEFF Research Database (Denmark)

    Nath, Sunil; Villadsen, John

    2015-01-01

    The fundamentals of oxidative phosphorylation and photophosphorylation are revisited. New experimental data on the involvement of succinate and malate anions respectively in oxidative phosphorylation and photophosphorylation are presented. These new data offer a novel molecular mechanistic...

  16. Nanoscopic platinum particles on TiO{sub 2}(110). STM and point-contact studies on the chemical and photosensitivity; Nanoskopische Platin-Teilchen auf TiO{sub 2}(110). STM- und Punktkontaktuntersuchungen zur chemischen und Photosensitivitaet

    Energy Technology Data Exchange (ETDEWEB)

    Koelbach, Johannes Micha

    2009-06-23

    In the ultra high vacuum produced nanoscopical platinum particles on TiO{sub 2}(110)- single crystal surfaces are contacted with the tunneltip of a raster tunnel microscope, and the chemical as well as photo sensitivity of an individual hetero contact are determined. For the experiments a UHV equipment was developed, equipped with methods to the controlled preparation and surface-analytic techniques (LEED, AES and STM). Platinum is resistively evaporated and thus small platinum particles with a size of about 8nm are generated on the pure titanium dioxide surface and characterized by STM and STS. A new developed oxygen source based on zirconoxide ceramics enables in-situ experiments for undisturbed determination of current-voltage characteristics in the tunneling and contact mode. A special preamplifier with controllable range of amplification is applied. Applying a voltage to the ceramic oxygen can be let into the UHV chamber by the oxygen source and the partial pressure can be adjusted within the range of 1.10{sup -10} mbar to 1.10{sup -5} mbar. The effect of the oxygen on the electrical characteristics of the Pt/TiO{sub 2}-contacts was proven. The clear dependence of the current-voltage characteristics on the oxygen partial pressure can be explained as a result of interface states due to the dissociation and adsorption of the oxygen, which determine the electrical characteristic of the contact. Schottky barriere heights and quality parameters were determined and compared with values of macroscopic surface contacts. For the investigations of the photo sensitivity a special STM head was developed, which enables the coupling of laser light with a wavelength of 413.1 nm. Irradiation of the nanoscopical Pt/TiO{sub 2}-contacts changes the current-voltage characteristics as well. The results of the power-dependent measurements refer to a temperature effect, that dominates the photoelectric effect. The combined power-and oxygen partial pressure dependent measurements are

  17. Circular revisit orbits design for responsive mission over a single target

    Science.gov (United States)

    Li, Taibo; Xiang, Junhua; Wang, Zhaokui; Zhang, Yulin

    2016-10-01

    The responsive orbits play a key role in addressing the mission of Operationally Responsive Space (ORS) because of their capabilities. These capabilities are usually focused on supporting specific targets as opposed to providing global coverage. One subtype of responsive orbits is repeat coverage orbit which is nearly circular in most remote sensing applications. This paper deals with a special kind of repeating ground track orbit, referred to as circular revisit orbit. Different from traditional repeat coverage orbits, a satellite on circular revisit orbit can visit a target site at both the ascending and descending stages in one revisit cycle. This typology of trajectory allows a halving of the traditional revisit time and does a favor to get useful information for responsive applications. However the previous reported numerical methods in some references often cost lots of computation or fail to obtain such orbits. To overcome this difficulty, an analytical method to determine the existence conditions of the solutions to revisit orbits is presented in this paper. To this end, the mathematical model of circular revisit orbit is established under the central gravity model and the J2 perturbation. A constraint function of the circular revisit orbit is introduced, and the monotonicity of that function has been studied. The existent conditions and the number of such orbits are naturally worked out. Taking the launch cost into consideration, optimal design model of circular revisit orbit is established to achieve a best orbit which visits a target twice a day in the morning and in the afternoon respectively for several days. The result shows that it is effective to apply circular revisit orbits in responsive application such as reconnoiter of natural disaster.

  18. Water adsorption on O(2x2)/Ru(0001) from STM experiments andfirst-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera-Sanfelix, P.; Sanchez-Portal, D.; Mugarza, A.; Shimizu,T.K.; Salmeron, M.; Arnau, A.

    2007-10-15

    We present a combined theoretical and experimental study of water adsorption on Ru(0001) pre-covered with 0.25 monolayers (ML) of oxygen forming a (2 x 2) structure. Several structures were analyzed by means of Density Functional Theory calculations for which STM simulations were performed and compared with experimental data. Up to 0.25 monolayers the molecules bind to the exposed Ru atoms of the 2 x 2 unit cell via the lone pair orbitals. The molecular plane is almost parallel to the surface with its H atoms pointing towards the chemisorbed O atoms of the 2 x 2 unit cell forming hydrogen bonds. The existence of these additional hydrogen bonds increases the adsorption energy of the water molecule to approximately 616 meV, which is {approx}220 meV more stable than on the clean Ru(0001) surface with a similar configuration. The binding energy shows only a weak dependence on water coverage, with a shallow minimum for a row structure at 0.125 ML. This is consistent with the STM experiments that show a tendency of the molecules to form linear rows at intermediate coverage. Our calculations also suggest the possible formation of water dimers near 0.25 ML.

  19. Bi-dimensional arrays of SPAD for time-resolved single photon imaging

    International Nuclear Information System (INIS)

    Tudisco, S.; Lanzano, L.; Musumeci, F.; Neri, L.; Privitera, S.; Scordino, A.; Condorelli, G.; Fallica, G.; Mazzillo, M.; Sanfilippo, D.; Valvo, G.

    2009-01-01

    Many scientific areas like astronomy, biophysics, biomedicine, nuclear and plasma science, etc. are interested in the development of a new time-resolved single photon imaging device. Such a device represents today one of the most challenging goals in the field of photonics. In collaboration with Catania R and D staff of ST-Microelectronics (STM) we created, during the last few years, a new avalanche photosensor-Single Photon Avalanche Diode (SPAD) able to detect and count, with excellent performance, single photons. Further we will discuss the possible realization of a single photon imaging device through the many elements integration (bi-dimensional arrays) of SPADs. In order to achieve the goal, it is also important to develop an appropriate readout strategy able to address the time information of each individual sensor and in order to read a great number of elements easily. First prototypes were designed and manufactured by STM and the results are reported here. In the paper we will discuss in particular: (i) sensor performance (gain, photodetection efficiency, timing, after-pulsing, etc.); (ii) array performance (layout, cross-talk, etc.); (iii) readout strategy (quenching, electronics), and (iv) first imaging results (general performance).

  20. New sub-family of lysozyme-like proteins shows no catalytic activity: crystallographic and biochemical study of STM3605 protein from Salmonella Typhimurium

    Energy Technology Data Exchange (ETDEWEB)

    Michalska, Karolina; Brown, Roslyn N.; Li, Hui; Jedrzejczak, Robert; Niemann, George; Heffron, Fred; Cort, John R.; Adkins, Joshua N.; Babnigg, Gyorgy; Joachimiak, Andrzej

    2013-03-01

    Phage viruses that infect prokaryotes integrate their genome into the host chromosome; thus, microbial genomes typically contain genetic remnants of both recent and ancient phage infections. Often phage genes occur in clusters of atypical G+C content that reflect integration of the foreign DNA. However, some phage genes occur in isolation without other phage gene neighbors, probably resulting from horizontal gene transfer. In these cases, the phage gene product is unlikely to function as a component of a mature phage particle, and instead may have been co-opted by the host for its own benefit. The product of one such gene from Salmonella enterica serovar Typhimurium, STM3605, encodes a protein with modest sequence similarity to phage-like lysozyme (N-acetylmuramidase) but appears to lack essential catalytic residues that are strictly conserved in all lysozymes. Close homologs in other bacteria share this characteristic. The structure of the STM3605 protein was characterized by X-ray crystallography, and functional assays showed that it is a stable, folded protein whose structure closely resembles lysozyme. However, this protein is unlikely to hydrolyze peptidoglycan. Instead, STM3605 is presumed to have evolved an alternative function because it shows some lytic activity and partitions to micelles.

  1. Growth of Ag thin films on ZnO(0 0 0 -1) investigated by AES and STM

    Energy Technology Data Exchange (ETDEWEB)

    Duriau, E. [Interuniversity Microelectronic Center (IMEC), SPDT-MCA, Kapeldreef 75, B-3001 Leuven (Belgium); Agouram, S. [Dpto. Fisica Aplicada y Electromagnetismo c/Dr. Moliner no. 50, 46100 Burjassot, Valencia (Spain); Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Morhain, C. [Centre de Recherche sur l' HeteroEpitaxie et ses Applications (CRHEA), CNRS, Rue Bernard Gregory, F-06560 Valbonne Sophia-Antipolis (France); Seldrum, T. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Sporken, R. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Dumont, J. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium)]. E-mail: jacques.dumont@fundp.ac.be

    2006-11-15

    The growth of Ag films on ZnO(0 0 0 -1) has been investigated by Auger electron spectroscopy (AES) and scanning tunneling microscopy (STM). A high density of islands is nucleated at the earliest stages of the growth. An upstepping mechanism causes these islands to coalesce while the uncovered fraction of the ZnO surface remains constant (30%)

  2. Recent STM, DFT and HAADF-STEM studies of sulfide-based hydrotreating catalysts: Insight into mechanistic, structural and particle size effects

    DEFF Research Database (Denmark)

    Besenbacher, Flemming; Brorson, M.; Clausen, B.S.

    2008-01-01

    The present article will highlight some recent experimental and theoretical studies of both unpromoted MoS2 and promoted Co-Mo-S and NiMo-S nanostructures. Particular emphasis will be given to discussion of our scanning tunnelling microscopy (STM), density functional theory (I)FT), and high...... and support effects which play an important role in practical HDS. Recent STM studies have shown that MoS2 clusters below 2-3 nm may exhibit new structural and electronic properties, and a large variety of size-dependent structures have been identified. In view of the large structure sensitivity......-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) studies which have provided insight into the detailed atomic structure. In accordance with earlier theoretical studies, the experimental studies show that the Ni-Mo-S structures may in some instances differ from the Co...

  3. Exploring routes to tailor the physical and chemical properties of oxides via doping: an STM study

    International Nuclear Information System (INIS)

    Nilius, Niklas

    2015-01-01

    Doping opens fascinating possibilities for tailoring the electronic, optical, magnetic, and chemical properties of oxides. The dopants perturb the intrinsic behavior of the material by generating charge centers for electron transfer into adsorbates, by inducing new energy levels for electronic and optical excitations, and by altering the surface morphology and hence the adsorption and reactivity pattern. Despite a vivid scientific interest, knowledge on doped oxides is limited when compared to semiconductors, which reflects the higher complexity and the insulating nature of many oxides. In fact, atomic-scale studies, aiming at a mechanistic understanding of dopant-related processes, are still scarce.In this article, we review our scanning tunneling microscopy (STM) experiments on thin, crystalline oxide films with a defined doping level. We demonstrate how the impurities alter the surface morphology and produce cationic/anionic vacancies in order to keep the system charge neutral. We discuss how individual dopants can be visualized in the lattice, even if they reside in subsurface layers. By means of STM-conductance and x-ray photoelectron spectroscopy, we determine the electronic impact of dopants, including the energies of their eigen states and local band-bending effects in the host oxide. Electronic transitions between dopant-induced gap states give rise to new optical modes, as detected with STM luminescence spectroscopy. From a chemical perspective, dopants are introduced to improve the redox potential of oxide materials. Electron transfer from Mo-donors, for example, alters the growth behavior of gold and activates O 2 molecules on a wide-gap CaO surface. Such results demonstrate the enormous potential of doped oxides in heterogeneous catalysis. Our experiments address the issue of doping from a fundamental viewpoint, posing questions on the lattice position, charge state, and electron-transfer potential of the impurity ions. Whether doped oxides are

  4. Exploring routes to tailor the physical and chemical properties of oxides via doping: an STM study

    Science.gov (United States)

    Nilius, Niklas

    2015-08-01

    Doping opens fascinating possibilities for tailoring the electronic, optical, magnetic, and chemical properties of oxides. The dopants perturb the intrinsic behavior of the material by generating charge centers for electron transfer into adsorbates, by inducing new energy levels for electronic and optical excitations, and by altering the surface morphology and hence the adsorption and reactivity pattern. Despite a vivid scientific interest, knowledge on doped oxides is limited when compared to semiconductors, which reflects the higher complexity and the insulating nature of many oxides. In fact, atomic-scale studies, aiming at a mechanistic understanding of dopant-related processes, are still scarce. In this article, we review our scanning tunneling microscopy (STM) experiments on thin, crystalline oxide films with a defined doping level. We demonstrate how the impurities alter the surface morphology and produce cationic/anionic vacancies in order to keep the system charge neutral. We discuss how individual dopants can be visualized in the lattice, even if they reside in subsurface layers. By means of STM-conductance and x-ray photoelectron spectroscopy, we determine the electronic impact of dopants, including the energies of their eigen states and local band-bending effects in the host oxide. Electronic transitions between dopant-induced gap states give rise to new optical modes, as detected with STM luminescence spectroscopy. From a chemical perspective, dopants are introduced to improve the redox potential of oxide materials. Electron transfer from Mo-donors, for example, alters the growth behavior of gold and activates O2 molecules on a wide-gap CaO surface. Such results demonstrate the enormous potential of doped oxides in heterogeneous catalysis. Our experiments address the issue of doping from a fundamental viewpoint, posing questions on the lattice position, charge state, and electron-transfer potential of the impurity ions. Whether doped oxides are

  5. Scholarly context not found: one in five articles suffers from reference rot.

    Directory of Open Access Journals (Sweden)

    Martin Klein

    Full Text Available The emergence of the web has fundamentally affected most aspects of information communication, including scholarly communication. The immediacy that characterizes publishing information to the web, as well as accessing it, allows for a dramatic increase in the speed of dissemination of scholarly knowledge. But, the transition from a paper-based to a web-based scholarly communication system also poses challenges. In this paper, we focus on reference rot, the combination of link rot and content drift to which references to web resources included in Science, Technology, and Medicine (STM articles are subject. We investigate the extent to which reference rot impacts the ability to revisit the web context that surrounds STM articles some time after their publication. We do so on the basis of a vast collection of articles from three corpora that span publication years 1997 to 2012. For over one million references to web resources extracted from over 3.5 million articles, we determine whether the HTTP URI is still responsive on the live web and whether web archives contain an archived snapshot representative of the state the referenced resource had at the time it was referenced. We observe that the fraction of articles containing references to web resources is growing steadily over time. We find one out of five STM articles suffering from reference rot, meaning it is impossible to revisit the web context that surrounds them some time after their publication. When only considering STM articles that contain references to web resources, this fraction increases to seven out of ten. We suggest that, in order to safeguard the long-term integrity of the web-based scholarly record, robust solutions to combat the reference rot problem are required. In conclusion, we provide a brief insight into the directions that are explored with this regard in the context of the Hiberlink project.

  6. Formation of Rh-Au core-shell nanoparticles on TiO.sub.2./sub.(110) surface studied by STM and LEIS

    Czech Academy of Sciences Publication Activity Database

    Óvari, L.; Berkó, A.; Balázs, N.; Majzik, Zsolt; Kiss, J.

    2010-01-01

    Roč. 26, č. 3 (2010), s. 2167-2175 ISSN 0743-7463 Institutional research plan: CEZ:AV0Z10100521 Keywords : surface diffusion of gold * STM * LEIS Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.269, year: 2010

  7. Simulation of the soft-landing and adsorption of C{sub 60} molecules on a graphite substrate and computation of their scanning-tunnelling-microscopy-like images

    Energy Technology Data Exchange (ETDEWEB)

    Rafii-Tabar, H. [Computational Nano-Science Research Group, Centre for Numerical Modelling and Process Analysis, School of Computing and Mathematical Sciences, University of Greenwich, Greenwich, London (United Kingdom); Jurczyszyn, L.; Stankiewicz, B. [Institute of Experimental Physics, University of Wroclaw, Wroclaw (Poland)

    2000-07-03

    A constant-temperature molecular dynamics (MD) simulation was performed to model the soft-landing and adsorption of C{sub 60} molecules on a graphite substrate with the C{sub 60}s treated as soft molecules and released individually towards the substrate. The intra-molecular and intra-planar covalently bonding interactions were modelled by very accurate many-body potentials, and the non-bonding forces were derived from various pairwise potentials. The simulation extended over 1.6 million time steps covering a significant period of 160 picoseconds. The final alignment of the molecules on the surface agrees closely with that observed in an experiment based on scanning tunnelling microscopy (STM) on the same system, performed at room temperature and under ultrahigh-vacuum (UHV) conditions. Using a tungsten tip in a constant-current mode of imaging, we have also computed the STM-like images of one of the adsorbed molecules using a formulation of the STM tunnelling current based on Keldysh's non-equilibrium Green function formalism. Our aim has been to search for tip-induced states, which were speculated, on the basis of another STM-based experiment, performed in air, to form one of the possible origins of the extra features purported to have been observed in that experiment. We have not obtained any such states. (author)

  8. Shape analysis of single and stacked InAs quantum dots at the atomic level by cross-sectional STM

    NARCIS (Netherlands)

    Bruls, D.M.; Vugs, J.W.A.M.; Koenraad, P.M.; Skolnick, M.S.; Hopkinson, M.; Wolter, J.H.; Miura, N.; Ando, T.

    2001-01-01

    We present a study of InAs self-assembled quantum dots in GaAs by cross-sectional scanning tunneling microscopy (X-STM). Our results shows that the dots consist of an JnGaAs alloy and that the indium content increases towards the top. The analysis of the height versus base length relation obtained

  9. Identification of surface defects and subsurface dopants in a delta-doped system using simultaneous nc-AFM/STM and DFT

    Czech Academy of Sciences Publication Activity Database

    Spadafora, Evan; Berger, Jan; Mutombo, Pingo; Telychko, Mykola; Švec, Martin; Majzik, Zsolt; McLean, A.B.; Jelínek, Pavel

    2014-01-01

    Roč. 118, č. 29 (2014), s. 15744-15753 ISSN 1932-7447 R&D Projects: GA ČR(CZ) GA14-02079S Institutional support: RVO:68378271 Keywords : doping * subsurface defects * nc-AFM * STM * KPFM * DFT Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.772, year: 2014

  10. Assessment of spatiotemporal fusion algorithms for Planet and Worldview images

    Science.gov (United States)

    Although Worldview (WV) images (non-pansharpened) have 2-meter resolution, the re-visit times for the same areas may be 7 days or more. In contrast, Planet images using small satellites can cover the whole Earth almost daily. However, the resolution of Planet images is 3.125 m. It will be ideal to f...

  11. Revisiting Okun's Relationship

    NARCIS (Netherlands)

    Dixon, R.; Lim, G.C.; van Ours, Jan

    2016-01-01

    Our paper revisits Okun's relationship between observed unemployment rates and output gaps. We include in the relationship the effect of labour market institutions as well as age and gender effects. Our empirical analysis is based on 20 OECD countries over the period 1985-2013. We find that the

  12. Nanofabrication with the Scanning Tunneling Microscope

    Energy Technology Data Exchange (ETDEWEB)

    Shedd, G.M.; Russell, P.E.

    1988-12-01

    The Precision Engineering Center has recently begun a research program into applications of STM to Nanotechnology. Few tools permit humans to control events and processes at the manometer level, and of those, the STM is the most well-suited to the task. A versatile new ultra-high-vacuum (UHV) STM is being built to study the use of STM for the manipulation of nanometer-scale particles. Part of the STM`s usefulness will be due to its being positioned directly beneath the focused ion beam (FIB). The interface of the STM with the FIB will allow the STM to take advantage of the FIB for long-range imaging and as a particle source; the FIB can in turn use the STM for in situ, high-resolution imaging of micromachined features.

  13. A new recipe for preparing oxidized TiO2(1 1 0) surfaces: An STM study

    Science.gov (United States)

    Hansen, Jonas Ø.; Matthiesen, Jesper; Lira, Estephania; Lammich, Lutz; Wendt, Stefan

    2017-12-01

    Using high-resolution scanning tunneling microscopy (STM), we have studied the oxidation of rutile TiO2(1 1 0)-(1 × 1) surfaces with Had species at room temperature. We followed the evolution of various stable species as function of the O2 exposure, and the nature of the ultimately dominating species in the Ti troughs is described. When O2 saturation was accomplished using a glass-capillary array doser, we found that on-top O (Oot) adatoms are the predominant surface species. In contrast, when O2 was supplied via backfilling of the chamber the predominant surface species are tentatively assigned to terminal OH groups. We argue that unintended reactions with the chamber walls have a strong influence on the formed surface species, explaining scattered results in the literature. On the basis of our STM data we propose an alternative, easy way of preparing oxidized TiO2(1 1 0) surfaces with Oot adatoms (o-TiO2). It is certain that o-TiO2(1 1 0) surfaces prepared according to this recipe do not have any residual surface O vacancies. This contradicts the situation when oxidizing reduced TiO2(1 1 0) surfaces with O vacancies, where some O vacancies persist.

  14. Inhomogeneous electronic structures in heavily Pb-doped Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} single crystals probed by low temperature STM/STS

    Energy Technology Data Exchange (ETDEWEB)

    Kinoda, Go; Nakao, Shoichiro; Motohashi, Teruki; Nakayama, Yuri; Shimizu, Keisuke; Shimoyama, Junichi; Kishio, Koji; Hanaguri, Tetsuo; Kitazawa, Koichi; Hasegawa, Tetsuya

    2003-05-15

    We have performed cryogenic scanning tunneling microscopy/spectroscopy (STM/STS) of heavily Pb-doped Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} single crystals to investigate local electronic structures in the overdoped regime. The obtained STM/STS results at 4.3 K clearly showed local inhomogeneity of gap structure {delta} ({delta}=20-60 meV) in a scale of several nm, suggesting the coexistence of superconducting and pseudogap-like regions, even in the overdoped regime.

  15. Tourists' perceptions and intention to revisit Norway

    OpenAIRE

    Lazar, Ana Florina; Komolikova-Blindheim, Galyna

    2016-01-01

    Purpose - The overall purpose of this study is to explore tourists' perceptions and their intention to revisit Norway. The aim is to find out what are the factors that drive the overall satisfaction, the willingness to recommend and the revisit intention of international tourists that spend their holiday in Norway. Design-Method-Approach - the Theory of Planned Behavior (Ajzen 1991), is used as a framework to investigate tourists' intention and behavior towards Norway as destination. The o...

  16. A new approach for agroecosystems monitoring using high-revisit multitemporal satellite data series

    Science.gov (United States)

    Diez, M.; Moclán, C.; Romo, A.; Pirondini, F.

    2014-10-01

    With increasing population pressure throughout the world and the need for increased agricultural production there is a definite need for improved management of the world's agricultural resources. Comprehensive, reliable and timely information on agricultural resources is necessary for the implementation of effective management decisions. In that sense, the demand for high-quality and high-frequency geo-information for monitoring of agriculture and its associated ecosystems has been growing in the recent decades. Satellite image data enable direct observation of large areas at frequent intervals and therefore allow unprecedented mapping and monitoring of crops evolution. Furthermore, real time analysis can assist in making timely management decisions that affect the outcome of the crops. The DEIMOS-1 satellite, owned and operated by ELECNOR DEIMOS IMAGING (Spain), provides 22m, 3-band imagery with a very wide (620-km) swath, and has been specifically designed to produce high-frequency revisit on very large areas. This capability has been proved through the contracts awarded to Airbus Defence and Space every year since 2011, where DEIMOS-1 has provided the USDA with the bulk of the imagery used to monitor the crop season in the Lower 48, in cooperation with its twin satellite DMCii's UK-DMC2. Furthermore, high density agricultural areas have been targeted with increased frequency and analyzed in near real time to monitor tightly the evolution. In this paper we present the results obtained from a campaign carried out in 2013 with DEIMOS-1 and UK-DMC2 satellites. These campaigns provided a high-frequency revisit of target areas, with one image every two days on average: almost a ten-fold frequency improvement with respect to Landsat-8. The results clearly show the effectiveness of a high-frequency monitoring approach with high resolution images with respect to classic strategies where results are more exposed to weather conditions.

  17. Embedded image processing engine using ARM cortex-M4 based STM32F407 microcontroller

    International Nuclear Information System (INIS)

    Samaiya, Devesh

    2014-01-01

    Due to advancement in low cost, easily available, yet powerful hardware and revolution in open source software, urge to make newer, more interactive machines and electronic systems have increased manifold among engineers. To make system more interactive, designers need easy to use sensor systems. Giving the boon of vision to machines was never easy, though it is not impossible these days; it is still not easy and expensive. This work presents a low cost, moderate performance and programmable Image processing engine. This Image processing engine is able to capture real time images, can store the images in the permanent storage and can perform preprogrammed image processing operations on the captured images

  18. Embedded image processing engine using ARM cortex-M4 based STM32F407 microcontroller

    Energy Technology Data Exchange (ETDEWEB)

    Samaiya, Devesh, E-mail: samaiya.devesh@gmail.com [Assistant Professor, School of Technology, The Glocal University, Mirzapur Pole, Saharanpur, Uttar Pradesh (India)

    2014-10-06

    Due to advancement in low cost, easily available, yet powerful hardware and revolution in open source software, urge to make newer, more interactive machines and electronic systems have increased manifold among engineers. To make system more interactive, designers need easy to use sensor systems. Giving the boon of vision to machines was never easy, though it is not impossible these days; it is still not easy and expensive. This work presents a low cost, moderate performance and programmable Image processing engine. This Image processing engine is able to capture real time images, can store the images in the permanent storage and can perform preprogrammed image processing operations on the captured images.

  19. Predictors and Outcomes of Revisits in Older Adults Discharged from the Emergency Department.

    Science.gov (United States)

    de Gelder, Jelle; Lucke, Jacinta A; de Groot, Bas; Fogteloo, Anne J; Anten, Sander; Heringhaus, Christian; Dekkers, Olaf M; Blauw, Gerard J; Mooijaart, Simon P

    2018-04-01

    To study predictors of emergency department (ED) revisits and the association between ED revisits and 90-day functional decline or mortality. Multicenter cohort study. One academic and two regional Dutch hospitals. Older adults discharged from the ED (N=1,093). At baseline, data on demographic characteristics, illness severity, and geriatric parameters (cognition, functional capacity) were collected. All participants were prospectively followed for an unplanned revisit within 30 days and for functional decline and mortality 90 days after the initial visit. The median age was 79 (interquartile range 74-84), and 114 participants (10.4%) had an ED revisit within 30 days of discharge. Age (hazard ratio (HR)=0.96, 95% confidence interval (CI)=0.92-0.99), male sex (HR=1.61, 95% CI=1.05-2.45), polypharmacy (HR=2.06, 95% CI=1.34-3.16), and cognitive impairment (HR=1.71, 95% CI=1.02-2.88) were independent predictors of a 30-day ED revisit. The area under the receiver operating characteristic curve to predict an ED revisit was 0.65 (95% CI=0.60-0.70). In a propensity score-matched analysis, individuals with an ED revisit were at higher risk (odds ratio=1.99 95% CI=1.06-3.71) of functional decline or mortality. Age, male sex, polypharmacy, and cognitive impairment were independent predictors of a 30-day ED revisit, but no useful clinical prediction model could be developed. However, an early ED revisit is a strong new predictor of adverse outcomes in older adults. © 2018 The Authors. The Journal of the American Geriatrics Society published by Wiley Periodicals, Inc. on behalf of The American Geriatrics Society.

  20. Sensemaking Revisited

    DEFF Research Database (Denmark)

    Holt, Robin; Cornelissen, Joep

    2014-01-01

    We critique and extend theory on organizational sensemaking around three themes. First, we investigate sense arising non-productively and so beyond any instrumental relationship with things; second, we consider how sense is experienced through mood as well as our cognitive skills of manipulation ...... research by revisiting Weick’s seminal reading of Norman Maclean’s book surrounding the tragic events of a 1949 forest fire at Mann Gulch, USA....

  1. Fabrication and in-situ STM investigation of growth dynamics of semiconductor nanostructures grown by MBE

    International Nuclear Information System (INIS)

    Borisova, Svetlana

    2012-01-01

    Modern development of information technologies requires an introduction of new fundamental concepts, in order to create more efficient devices and to decrease their size. One of the most promising ways is to increase the functionality of silicon by integrating novel materials into Si-based production. This PhD thesis reports on the fabrication and investigation of the growth of semiconductor nanostructures on Si substrates by molecular beam epitaxy (MBE). In-situ scanning tunneling microscopy (STM) is a powerful technique in order to study morphological and electronic properties of the grown structures directly under ultra high vacuum (UHV) conditions. It is shown that the combination of MBE and in-situ STM enables the study of nucleation and growth dynamics at the atomic scale. It provides us with numerous information concerning the nucleation mechanism, the growth mode of the structures, adatom kinetics, influence of the lattice mismatch between the substrate and the grown structure as well as formation and morphology of crystal defects. The first part of the thesis focuses on the experimental realization based upon an existing setup. The construction of an in-situ UHV STM compatible with the MBE cluster and the technical improvement of the STM setup are described. Subsequently, test measurements are performed on the technologically most important surfaces, Ge (100) and Si (111). The second part of the thesis is dedicated to ordered small-period arrays of self-assembled Ge quantum dots (QDs) grown on pre-patterned Si (100) substrates. Small-period Ge QD crystals are highly interesting since band structure calculations indicate coupled electronic states of the QDs in the case of the small lateral period of approximately 30 nm. Small-period hole patterns with a period of 56 nm are fabricated by e-beam lithography on Si substrates. The evolution of the hole morphology during the in-situ pre-growth annealing and the Si buffer layer growth are studied. Deposition of 5

  2. Fabrication and in-situ STM investigation of growth dynamics of semiconductor nanostructures grown by MBE

    Energy Technology Data Exchange (ETDEWEB)

    Borisova, Svetlana

    2012-05-23

    Modern development of information technologies requires an introduction of new fundamental concepts, in order to create more efficient devices and to decrease their size. One of the most promising ways is to increase the functionality of silicon by integrating novel materials into Si-based production. This PhD thesis reports on the fabrication and investigation of the growth of semiconductor nanostructures on Si substrates by molecular beam epitaxy (MBE). In-situ scanning tunneling microscopy (STM) is a powerful technique in order to study morphological and electronic properties of the grown structures directly under ultra high vacuum (UHV) conditions. It is shown that the combination of MBE and in-situ STM enables the study of nucleation and growth dynamics at the atomic scale. It provides us with numerous information concerning the nucleation mechanism, the growth mode of the structures, adatom kinetics, influence of the lattice mismatch between the substrate and the grown structure as well as formation and morphology of crystal defects. The first part of the thesis focuses on the experimental realization based upon an existing setup. The construction of an in-situ UHV STM compatible with the MBE cluster and the technical improvement of the STM setup are described. Subsequently, test measurements are performed on the technologically most important surfaces, Ge (100) and Si (111). The second part of the thesis is dedicated to ordered small-period arrays of self-assembled Ge quantum dots (QDs) grown on pre-patterned Si (100) substrates. Small-period Ge QD crystals are highly interesting since band structure calculations indicate coupled electronic states of the QDs in the case of the small lateral period of approximately 30 nm. Small-period hole patterns with a period of 56 nm are fabricated by e-beam lithography on Si substrates. The evolution of the hole morphology during the in-situ pre-growth annealing and the Si buffer layer growth are studied. Deposition of 5

  3. Spectroscopic scanning tunneling microscopy insights into Fe-based superconductors

    International Nuclear Information System (INIS)

    Hoffman, Jennifer E

    2011-01-01

    In the first three years since the discovery of Fe-based high T c superconductors, scanning tunneling microscopy (STM) and spectroscopy have shed light on three important questions. First, STM has demonstrated the complexity of the pairing symmetry in Fe-based materials. Phase-sensitive quasiparticle interference (QPI) imaging and low temperature spectroscopy have shown that the pairing order parameter varies from nodal to nodeless s± within a single family, FeTe 1-x Se x . Second, STM has imaged C4 → C2 symmetry breaking in the electronic states of both parent and superconducting materials. As a local probe, STM is in a strong position to understand the interactions between these broken symmetry states and superconductivity. Finally, STM has been used to image the vortex state, giving insights into the technical problem of vortex pinning, and the fundamental problem of the competing states introduced when superconductivity is locally quenched by a magnetic field. Here we give a pedagogical introduction to STM and QPI imaging, discuss the specific challenges associated with extracting bulk properties from the study of surfaces, and report on progress made in understanding Fe-based superconductors using STM techniques.

  4. Destination Brand Equity, Satisfaction And Revisit Intention: An Application In TRNC As a Tourism Destination

    OpenAIRE

    Sarvari, Neda Gholizadeh

    2012-01-01

    ABSTRACT: This study revisits the previous studies carried out by several researchers on Customer – Based Brand Equity with an intension to further investigate the applications and testing of the Customer-Based Brand Equity (CBBE) model in relation to destination branding. The study specifically examines the effects of Brand Equity Dimensions (Brand Awareness, Brand Loyalty, Brand Value, Brand Quality and Brand Image) on Tourists Satisfaction and ultimately on Future Behaviours that result i...

  5. In situ scanning tunneling microscope tip treatment device for spin polarization imaging

    Science.gov (United States)

    Li, An-Ping [Oak Ridge, TN; Jianxing, Ma [Oak Ridge, TN; Shen, Jian [Knoxville, TN

    2008-04-22

    A tip treatment device for use in an ultrahigh vacuum in situ scanning tunneling microscope (STM). The device provides spin polarization functionality to new or existing variable temperature STM systems. The tip treatment device readily converts a conventional STM to a spin-polarized tip, and thereby converts a standard STM system into a spin-polarized STM system. The tip treatment device also has functions of tip cleaning and tip flashing a STM tip to high temperature (>2000.degree. C.) in an extremely localized fashion. Tip coating functions can also be carried out, providing the tip sharp end with monolayers of coating materials including magnetic films. The device is also fully compatible with ultrahigh vacuum sample transfer setups.

  6. Single Crystal Synthesis and STM Studies of High Temperature Superconductors

    Science.gov (United States)

    Barrientos, Alfonso

    1997-01-01

    This is a final report for the work initiated in September of 1994 under the grant NAG8-1085 - NASA/OMU, on the fabrication of bulk and single crystal synthesis, specific heat measuring and STM studies of high temperature superconductors. Efforts were made to fabricate bulk and single crystals of mercury based superconducting material. A systematic thermal analysis on the precursors for the corresponding oxides and carbonates were carried out to synthesized bulk samples. Bulk material was used as seed in an attempt to grow single crystals by a two-step self flux process. On the other hand bulk samples were characterized by x-ray diffraction, electrical resistivity and magnetic susceptibility, We studied the specific heat behavior in the range from 80 to 300 K. Some preliminary attempts were made to study the atomic morphology of our samples. As part of our efforts we built an ac susceptibility apparatus for measuring the transition temperature of our sintered samples.

  7. A Structural Equation Model of Risk Perception of Rockfall for Revisit Intention

    OpenAIRE

    Ya-Fen Lee; Yun-Yao Chi

    2014-01-01

    The study aims to explore the relationship between risk perception of rockfall and revisit intention using a Structural Equation Modeling (SEM) analysis. A total of 573 valid questionnaires are collected from travelers to Taroko National Park, Taiwan. The findings show the majority of travelers have the medium perception of rockfall risk, and are willing to revisit the Taroko National Park. The revisit intention to Taroko National Park is influenced by hazardous preferences, willingness-to-pa...

  8. Design of a high-speed electrochemical scanning tunneling microscope.

    Science.gov (United States)

    Yanson, Y I; Schenkel, F; Rost, M J

    2013-02-01

    In this paper, we present a bottom-up approach to designing and constructing a high-speed electrochemical scanning tunneling microscope (EC-STM). Using finite element analysis (FEA) calculations of the frequency response of the whole mechanical loop of the STM, we analyzed several geometries to find the most stable one that could facilitate fast scanning. To test the FEA results, we conducted measurements of the vibration amplitudes using a prototype STM setup. Based on the FEA analysis and the measurement results, we identified the potentially most disturbing vibration modes that could impair fast scanning. By modifying the design of some parts of the EC-STM, we reduced the amplitudes as well as increased the resonance frequencies of these modes. Additionally, we designed and constructed an electrochemical flow-cell that allows STM imaging in a flowing electrolyte, and built a bi-potentiostat to achieve electrochemical potential control during the measurements. Finally, we present STM images acquired during high-speed imaging in air as well as in an electrochemical environment using our newly-developed EC-STM.

  9. The Faraday effect revisited

    DEFF Research Database (Denmark)

    Cornean, Horia; Nenciu, Gheorghe

    2009-01-01

    This paper is the second in a series revisiting the (effect of) Faraday rotation. We formulate and prove the thermodynamic limit for the transverse electric conductivity of Bloch electrons, as well as for the Verdet constant. The main mathematical tool is a regularized magnetic and geometric...

  10. Remembered Experiences and Revisit Intentions

    DEFF Research Database (Denmark)

    Barnes, Stuart; Mattsson, Jan; Sørensen, Flemming

    2016-01-01

    Tourism is an experience-intensive sector in which customers seek and pay for experiences above everything else. Remembering past tourism experiences is also crucial for an understanding of the present, including the predicted behaviours of visitors to tourist destinations. We adopt a longitudinal...... approach to memory data collection from psychological science, which has the potential to contribute to our understanding of tourist behaviour. In this study, we examine the impact of remembered tourist experiences in a safari park. In particular, using matched survey data collected longitudinally and PLS...... path modelling, we examine the impact of positive affect tourist experiences on the development of revisit intentions. We find that longer-term remembered experiences have the strongest impact on revisit intentions, more so than predicted or immediate memory after an event. We also find that remembered...

  11. Bi surfactant mediated growth for fabrication of Si/Ge nanostructures and investigation of Si/Ge intermixing by STM

    Energy Technology Data Exchange (ETDEWEB)

    Paul, N.

    2007-10-26

    In the thesis work presented here, we show that Bi is more promising surfactant material than Sb. We demonstrate that by using Bi as a terminating layer on Ge/Si surface, it is possible to distinguish between Si and Ge in Scanning tunnelling microscope (STM). Any attempt to utilize surfactant mediated growth must be preceded by a thorough study of its effect on the the system being investigated. Thus, the third chapter of this thesis deals with an extensive study of the Bi surfactant mediated growth of Ge on Si(111) surface as a function of Ge coverage. The growth is investigated from the single bilayer Ge coverage till the Ge coverage of about 15 BL when the further Ge deposition leads to two-dimensional growth. In the fourth chapter, the unique property of Bi terminating layer on Ge/Si surface to result in an STM height contrast between Si and Ge is explained with possible explanations given for the reason of this apparent height contrast. The controlled fabrication of Ge/Si nanostructures such as nanowires and nanorings is demonstrated. A study on Ge-Si diffusion in the surface layers by a direct method such as STM was impossible previously because of the similar electronic structure of Ge and Si. Since with the Bi terminating surface layer, one is able to distinguish between Ge and Si, the study of intermixing between them is also possible using STM. This method to distinguish between Si and Ge allows one to study intermixing on the nanoscale and to identify the fundamental diffusion processes giving rise to the intermixing. In Chapter 5 we discuss how this could prove useful especially as one could get a local probe over a very narrow Ge-Si interface. A new model is proposed to estimate change in the Ge concentration in the surface layer with time. The values of the activation energies of Ge/Si exchange and Si/Ge exchange are estimated by fitting the experimental data with the model. The Ge/Si intermixing has been studied on a surface having 1 ML Bi ({radical

  12. Revisiting the Okun relationship

    NARCIS (Netherlands)

    Dixon, R. (Robert); Lim, G.C.; J.C. van Ours (Jan)

    2017-01-01

    textabstractOur article revisits the Okun relationship between observed unemployment rates and output gaps. We include in the relationship the effect of labour market institutions as well as age and gender effects. Our empirical analysis is based on 20 OECD countries over the period 1985–2013. We

  13. Bounded Intention Planning Revisited

    OpenAIRE

    Sievers Silvan; Wehrle Martin; Helmert Malte

    2014-01-01

    Bounded intention planning provides a pruning technique for optimal planning that has been proposed several years ago. In addition partial order reduction techniques based on stubborn sets have recently been investigated for this purpose. In this paper we revisit bounded intention planning in the view of stubborn sets.

  14. Revisiting Nursing Research in Nigeria

    African Journals Online (AJOL)

    2016-08-18

    Aug 18, 2016 ... health care research, it is therefore pertinent to revisit the state of nursing research in the country. .... platforms, updated libraries with electronic resource ... benchmarks for developing countries of 26%, [17] the amount is still ...

  15. Time functions revisited

    Science.gov (United States)

    Fathi, Albert

    2015-07-01

    In this paper we revisit our joint work with Antonio Siconolfi on time functions. We will give a brief introduction to the subject. We will then show how to construct a Lipschitz time function in a simplified setting. We will end with a new result showing that the Aubry set is not an artifact of our proof of existence of time functions for stably causal manifolds.

  16. Transcriptomic profiling of Burkholderia phymatum STM815, Cupriavidus taiwanensis LMG19424 and Rhizobium mesoamericanum STM3625 in response to Mimosa pudica root exudates illuminates the molecular basis of their nodulation competitiveness and symbiotic evolutionary history.

    Science.gov (United States)

    Klonowska, Agnieszka; Melkonian, Rémy; Miché, Lucie; Tisseyre, Pierre; Moulin, Lionel

    2018-01-30

    Rhizobial symbionts belong to the classes Alphaproteobacteria and Betaproteobacteria (called "alpha" and "beta"-rhizobia). Most knowledge on the genetic basis of symbiosis is based on model strains belonging to alpha-rhizobia. Mimosa pudica is a legume that offers an excellent opportunity to study the adaptation toward symbiotic nitrogen fixation in beta-rhizobia compared to alpha-rhizobia. In a previous study (Melkonian et al., Environ Microbiol 16:2099-111, 2014) we described the symbiotic competitiveness of M. pudica symbionts belonging to Burkholderia, Cupriavidus and Rhizobium species. In this article we present a comparative analysis of the transcriptomes (by RNAseq) of B. phymatum STM815 (BP), C. taiwanensis LMG19424 (CT) and R. mesoamericanum STM3625 (RM) in conditions mimicking the early steps of symbiosis (i.e. perception of root exudates). BP exhibited the strongest transcriptome shift both quantitatively and qualitatively, which mirrors its high competitiveness in the early steps of symbiosis and its ancient evolutionary history as a symbiont, while CT had a minimal response which correlates with its status as a younger symbiont (probably via acquisition of symbiotic genes from a Burkholderia ancestor) and RM had a typical response of Alphaproteobacterial rhizospheric bacteria. Interestingly, the upregulation of nodulation genes was the only common response among the three strains; the exception was an up-regulated gene encoding a putative fatty acid hydroxylase, which appears to be a novel symbiotic gene specific to Mimosa symbionts. The transcriptional response to root exudates was correlated to each strain nodulation competitiveness, with Burkholderia phymatum appearing as the best specialised symbiont of Mimosa pudica.

  17. Self-assembled organic radicals on Au(111) surfaces: a combined ToF-SIMS, STM, and ESR study.

    Science.gov (United States)

    Mannini, Matteo; Sorace, Lorenzo; Gorini, Lapo; Piras, Federica M; Caneschi, Andrea; Magnani, Agnese; Menichetti, Stefano; Gatteschi, Dante

    2007-02-27

    Electron spin resonance (ESR), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and scanning tunneling microscopy (STM) have been used in parallel to characterize the deposition on gold surface of a series of nitronyl nitroxide radicals. These compounds have been specifically synthesized with methyl-thio linking groups suitable to interact with the gold surface to form self-assembled monolayers (SAMs), which can be considered relevant in the research for molecular-based spintronics devices, as suggested in recent papers. The degree of the expected ordering on the surface of these SAMs has been tuned by varying the chemical structure of synthesized radicals. ToF-SIMS has been used to support the evidence of the occurrence of the deposition process. STM has shown the different qualities of the obtained SAMs, with the degree of local order increasing as the degree of freedom of the molecules on the surface is decreased. Finally, ESR has confirmed that the deposition process does not affect the paramagnetic characteristics of radicals and that it affords a complete single-layered coverage of the surface. Further, the absence of angular dependence in the spectra indicates that the small regions of local ordering do not give rise to a long-range order and suggests a quite large mobility of the radical on the surface, probably due to the weak interaction with gold provided by the methyl-thio linking group.

  18. Structure of a zinc oxide ultra-thin film on Rh(100)

    Energy Technology Data Exchange (ETDEWEB)

    Yuhara, J.; Kato, D.; Matsui, T. [Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Mizuno, S. [Department of Molecular and Material Sciences, Kyushu University, Kasuga, Fukuoka 816–8580 (Japan)

    2015-11-07

    The structural parameters of ultra-thin zinc oxide films on Rh(100) are investigated using low-energy electron diffraction intensity (LEED I–V) curves, scanning tunneling microscopy (STM), and first-principles density functional theory (DFT) calculations. From the analysis of LEED I–V curves and DFT calculations, two optimized models A and B are determined. Their structures are basically similar to the planer h-BN ZnO(0001) structure, although some oxygen atoms protrude from the surface, associated with an in-plane shift of Zn atoms. From a comparison of experimental STM images and simulated STM images, majority and minority structures observed in the STM images represent the two optimized models A and B, respectively.

  19. Moiré pattern induced by the electronic coupling between 1-octanol self-assembled monolayers and graphite surface

    International Nuclear Information System (INIS)

    Silly, Fabien

    2012-01-01

    Two-dimensional self-assembly of 1-octanol molecules on a graphite surface is investigated using scanning tunneling microscopy (STM) at the solid/liquid interface. STM images reveal that this molecule self-assembles into a compact hydrogen-bonded herringbone nanoarchitecture. Molecules are preferentially arranged in a head-to-head and tail-to-tail fashion. A Moiré pattern appears in the STM images when the 1-octanol layer is covering the graphite surface. The large Moiré stripes are perpendicular to the 1-octanol lamellae. Interpretation of the STM images suggests that the Moiré periodicity is governed by the electronic properties of the graphite surface and the 1-octanol layer periodicity. (paper)

  20. Revisiting tourist behavior via destination brand worldness

    Directory of Open Access Journals (Sweden)

    Murat Kayak

    2016-11-01

    Full Text Available Taking tourists’ perspective rather than destination offerings as its core concept, this study introduces “perceived destination brand worldness” as a variable. Perceived destination brand worldness is defined as the positive perception that a tourist has of a country that is visited by tourists from all over the world. Then, the relationship between perceived destination brand worldness and intention to revisit is analyzed using partial least squares regression. This empirical study selects Taiwanese tourists as its sample, and the results show that perceived destination brand worldness is a direct predictor of intention to revisit. In light of these empirical findings and observations, practical and theoretical implications are discussed.

  1. Surface morphology and in-plane-epitaxy of SmBa2Cu3O7-δ films on SrTiO3 (001) substrates studied by STM and grazing incidence x-ray diffraction

    DEFF Research Database (Denmark)

    Jiang, Q.D.; Smilgies, D.M.; Feidenhans'l, R.

    1996-01-01

    The surface morphology and in-plane epitaxy of thin films of SmBa(2)Cu3O(7-delta) (Sm-BCO) grown on SrTiO3 (001) substrates with various thicknesses have been investigated by scanning tunneling microscopy (STM) and grazing incidence x-ray diffraction (GIXRD). As revealed by GIXRD, SmBCO films as ...... films above h(c2), introduction of screw dislocations leads to spiral growth.......The surface morphology and in-plane epitaxy of thin films of SmBa(2)Cu3O(7-delta) (Sm-BCO) grown on SrTiO3 (001) substrates with various thicknesses have been investigated by scanning tunneling microscopy (STM) and grazing incidence x-ray diffraction (GIXRD). As revealed by GIXRD, SmBCO films...... substrate. Three different types of surface morphology were observed by STM with increasing film thickness h: a) 2D growth for hh(c2). With GIXRD, a density modulation is observed in the films with a thickness below h(c2). For thicker...

  2. Fusion of MODIS Images Using Kriging With External Drift

    NARCIS (Netherlands)

    Ribeiro Sales, M.H.; Souza, C.M.; Kyriakidis, P.C.

    2013-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) has been used in several remote sensing studies, including land, ocean, and atmospheric applications. The advantages of this sensor are its high spectral resolution, with 36 spectral bands; its high revisiting frequency; and its public domain

  3. Model-based satellite image fusion

    DEFF Research Database (Denmark)

    Aanæs, Henrik; Sveinsson, J. R.; Nielsen, Allan Aasbjerg

    2008-01-01

    A method is proposed for pixel-level satellite image fusion derived directly from a model of the imaging sensor. By design, the proposed method is spectrally consistent. It is argued that the proposed method needs regularization, as is the case for any method for this problem. A framework for pixel...... neighborhood regularization is presented. This framework enables the formulation of the regularization in a way that corresponds well with our prior assumptions of the image data. The proposed method is validated and compared with other approaches on several data sets. Lastly, the intensity......-hue-saturation method is revisited in order to gain additional insight of what implications the spectral consistency has for an image fusion method....

  4. Interpreting Interfacial Structure in Cross-Sectional STM Images of III-V Semiconductor Heterostructures

    National Research Council Canada - National Science Library

    Nosho, B. Z; Barvosa-Carter, W; Yang, M. J; Bennett, B. R; Whitman, L. J

    2000-01-01

    ...) can be used for the study of III-V heterostructure interfaces. The interpretation of interfacial structure in XSTM images is impeded by the fact that only every other III or V plane as grown on the (001...

  5. Ordering of Zn-centered porphyrin and phthalocyanine on TiO2(011: STM studies

    Directory of Open Access Journals (Sweden)

    Piotr Olszowski

    2017-01-01

    Full Text Available Zn(IIphthalocyanine molecules (ZnPc were thermally deposited on a rutile TiO2(011 surface and on Zn(IImeso-tetraphenylporphyrin (ZnTPP wetting layers at room temperature and after elevated temperature thermal processing. The molecular homo- and heterostructures were characterized by high-resolution scanning tunneling microscopy (STM at room temperature and their geometrical arrangement and degree of ordering are compared with the previously studied copper phthalocyanine (CuPc and ZnTPP heterostructures. It was found that the central metal atom may play some role in ordering and growth of phthalocyanine/ZnTPP heterostructures, causing differences in stability of upright standing ZnPc versus CuPc molecular chains at given thermal annealing conditions.

  6. Revisiting Inter-Genre Similarity

    DEFF Research Database (Denmark)

    Sturm, Bob L.; Gouyon, Fabien

    2013-01-01

    We revisit the idea of ``inter-genre similarity'' (IGS) for machine learning in general, and music genre recognition in particular. We show analytically that the probability of error for IGS is higher than naive Bayes classification with zero-one loss (NB). We show empirically that IGS does...... not perform well, even for data that satisfies all its assumptions....

  7. A Hydrostatic Paradox Revisited

    Science.gov (United States)

    Ganci, Salvatore

    2012-01-01

    This paper revisits a well-known hydrostatic paradox, observed when turning upside down a glass partially filled with water and covered with a sheet of light material. The phenomenon is studied in its most general form by including the mass of the cover. A historical survey of this experiment shows that a common misunderstanding of the phenomenon…

  8. Seven Issues, Revisited

    OpenAIRE

    Whitehead, Jim; De Bra, Paul; Grønbæk, Kaj; Larsen, Deena; Legget, John; schraefel, monica m.c.

    2002-01-01

    It has been 15 years since the original presentation by Frank Halasz at Hypertext'87 on seven issues for the next generation of hypertext systems. These issues are: Search and Query Composites Virtual Structures Computation in/over hypertext network Versioning Collaborative Work Extensibility and Tailorability Since that time, these issues have formed the nucleus of multiple research agendas within the Hypertext community. Befitting this direction-setting role, the issues have been revisited ...

  9. Superresolution Imaging Using Resonant Multiples

    KAUST Repository

    Guo, Bowen

    2017-12-22

    A resonant multiple is defined as a multiple reflection that revisits the same subsurface location along coincident reflection raypaths. We show that resonant first-order multiples can be migrated with either Kirchhoff or wave-equation migration methods to give images with approximately twice the spatial resolution compared to post-stack primary-reflection images. A moveout-correction stacking method is proposed to enhance the signal-to-noise ratios (SNRs) of the resonant multiples before superresolution migration. The effectiveness of this procedure is validated by synthetic and field data tests.

  10. Superresolution Imaging Using Resonant Multiples

    KAUST Repository

    Guo, Bowen; Schuster, Gerard T.

    2017-01-01

    A resonant multiple is defined as a multiple reflection that revisits the same subsurface location along coincident reflection raypaths. We show that resonant first-order multiples can be migrated with either Kirchhoff or wave-equation migration methods to give images with approximately twice the spatial resolution compared to post-stack primary-reflection images. A moveout-correction stacking method is proposed to enhance the signal-to-noise ratios (SNRs) of the resonant multiples before superresolution migration. The effectiveness of this procedure is validated by synthetic and field data tests.

  11. Leadership and Management Theories Revisited

    DEFF Research Database (Denmark)

    Madsen, Mona Toft

    2001-01-01

    The goal of the paper is to revisit and analyze key contributions to the understanding of leadership and management. As a part of the discussion a role perspective that allows for additional and/or integrated leader dimensions, including a change-centered, will be outlined. Seemingly, a major...

  12. Schroedinger's variational method of quantization revisited

    International Nuclear Information System (INIS)

    Yasue, K.

    1980-01-01

    Schroedinger's original quantization procedure is revisited in the light of Nelson's stochastic framework of quantum mechanics. It is clarified why Schroedinger's proposal of a variational problem led us to a true description of quantum mechanics. (orig.)

  13. Imaging by Electrochemical Scanning Tunneling Microscopy and Deconvolution Resolving More Details of Surfaces Nanomorphology

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    observed in high-resolution images of metallic nanocrystallites may be effectively deconvoluted, as to resolve more details of the crystalline morphology (see figure). Images of surface-crystalline metals indicate that more than a single atomic layer is involved in mediating the tunneling current......Upon imaging, electrochemical scanning tunneling microscopy (ESTM), scanning electrochemical micro-scopy (SECM) and in situ STM resolve information on electronic structures and on surface topography. At very high resolution, imaging processing is required, as to obtain information that relates...... to crystallographic-surface structures. Within the wide range of new technologies, those images surface features, the electrochemical scanning tunneling microscope (ESTM) provides means of atomic resolution where the tip participates actively in the process of imaging. Two metallic surfaces influence ions trapped...

  14. Measurement of mesoscopic Si:P delta-doped devices fabricated by rapid STM hydrogen depassivation lithography via field-emission

    Science.gov (United States)

    Rudolph, M.; Carr, S. M.; Subramania, G.; Ten Eyck, G.; Dominguez, J.; Lilly, M. P.; Carroll, M. S.; Bussmann, E.

    2014-03-01

    Recently, a method to fabricate nanoelectronic and quantum devices has been developed that utilizes scanning tunneling microscopy (STM) to place dopants (P) into Si with deterministic atomic-precision. Dopant placement is achieved via STM hydrogen depassivation lithography (HDL). Typically HDL is performed in a low-voltage tunneling mode where electrons desorb one H at a time, which requires extremely slow scan rates. Here, we introduce a high-voltage field-emission HDL, increasing patterning scan rate by an order of magnitude. Using the field-emission mode, we fabricated several HDL-patterned Si:P delta-doped devices, including a microscale multi-terminal Hall Effect device and a nanoscale quantum point contact. Low temperature transport measurements of the Hall device reveal a dopant density of 1014 cm-2, resistance of 2 k Ω/square, and mobility of 30 cm2/Vs. The quantum point contact showed a blockaded voltage range of 80 mV, comparable to other similar devices patterned using conventional HDL. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE, Office of Basic Energy Sciences user facility. The work was supported by the Sandia National Laboratories Directed Research and Development Program. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

  15. Manipulating a Co adatom on a stepped Cu surface by an STM tip: A theoretical study

    International Nuclear Information System (INIS)

    Liu, L.; Huang, R.Z.; Sun, Y.S.N.; Du, C.C.; Zhang, R.J.; Zheng, Y.X.; Wu, Y.X.

    2014-01-01

    A successful atomic manipulation may be influenced by many factors such as bias voltage, tip structure and manipulation modes et al. Here, performing atomic-scale simulations with ab initio based many-body potentials, we have studied the vertical and lateral manipulation of a single Co adatom on metallic Cu surfaces using STM tips at zero bias voltage. A suitable scheme for manipulating the Co adatom on a Cu(5 5 4) surface is proposed. The optimum tip height for a successful lateral manipulation is determined and the reliability of the lateral manipulation of the adatom on the stepped surface is assessed

  16. Insulating nanoparticles on YBa2Cu3O7-δ thin films revealed by comparison of atomic force and scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Thomson, R.E.; Moreland, J.; Missert, N.; Rudman, D.A.; Sanders, S.C.; Cole, B.F.

    1993-01-01

    The surface topography of YBa 2 Cu 3 O 7-δ thin films has been studied with both atomic force microscopy (AFM) and scanning tunneling microscopy (STM). The AFM images reveal a high density of small distinct nanoparticles, 10--50 nm across and 5--20 nm high, which do not appear in STM images of the same samples. In addition, we have shown that scanning the STM tip across the surface breaks off these particles and moves them to the edge of the scanned area, where they can later be imaged with the AFM

  17. Leukemia and ionizing radiation revisited

    Energy Technology Data Exchange (ETDEWEB)

    Cuttler, J.M. [Cuttler & Associates Inc., Vaughan, Ontario (Canada); Welsh, J.S. [Loyola University-Chicago, Dept. or Radiation Oncology, Stritch School of Medicine, Maywood, Illinois (United States)

    2016-03-15

    A world-wide radiation health scare was created in the late 19508 to stop the testing of atomic bombs and block the development of nuclear energy. In spite of the large amount of evidence that contradicts the cancer predictions, this fear continues. It impairs the use of low radiation doses in medical diagnostic imaging and radiation therapy. This brief article revisits the second of two key studies, which revolutionized radiation protection, and identifies a serious error that was missed. This error in analyzing the leukemia incidence among the 195,000 survivors, in the combined exposed populations of Hiroshima and Nagasaki, invalidates use of the LNT model for assessing the risk of cancer from ionizing radiation. The threshold acute dose for radiation-induced leukemia, based on about 96,800 humans, is identified to be about 50 rem, or 0.5 Sv. It is reasonable to expect that the thresholds for other cancer types are higher than this level. No predictions or hints of excess cancer risk (or any other health risk) should be made for an acute exposure below this value until there is scientific evidence to support the LNT hypothesis. (author)

  18. A safe vaccine (DV-STM-07 against Salmonella infection prevents abortion and confers protective immunity to the pregnant and new born mice.

    Directory of Open Access Journals (Sweden)

    Vidya Devi Negi

    Full Text Available Pregnancy is a transient immuno-compromised condition which has evolved to avoid the immune rejection of the fetus by the maternal immune system. The altered immune response of the pregnant female leads to increased susceptibility to invading pathogens, resulting in abortion and congenital defects of the fetus and a subnormal response to vaccination. Active vaccination during pregnancy may lead to abortion induced by heightened cell mediated immune response. In this study, we have administered the highly attenuated vaccine strain DeltapmrG-HM-D (DV-STM-07 in female mice before the onset of pregnancy and followed the immune reaction against challenge with virulent S. Typhimurium in pregnant mice. Here we demonstrate that DV-STM-07 vaccine gives protection against Salmonella in pregnant mice and also prevents Salmonella induced abortion. This protection is conferred by directing the immune response towards Th2 activation and Th1 suppression. The low Th1 response prevents abortion. The use of live attenuated vaccine just before pregnancy carries the risk of transmission to the fetus. We have shown that this vaccine is safe as the vaccine strain is quickly eliminated from the mother and is not transmitted to the fetus. This vaccine also confers immunity to the new born mice of vaccinated mothers. Since there is no evidence of the vaccine candidate reaching the new born mice, we hypothesize that it may be due to trans-colostral transfer of protective anti-Salmonella antibodies. These results suggest that our vaccine DV-STM-07 can be very useful in preventing abortion in the pregnant individuals and confer immunity to the new born. Since there are no such vaccine candidates which can be given to the new born and to the pregnant women, this vaccine holds a very bright future to combat Salmonella induced pregnancy loss.

  19. Theory of high-resolution tunneling spin transport on a magnetic skyrmion

    Science.gov (United States)

    Palotás, Krisztián; Rózsa, Levente; Szunyogh, László

    2018-05-01

    Tunneling spin transport characteristics of a magnetic skyrmion are described theoretically in magnetic scanning tunneling microscopy (STM). The spin-polarized charge current in STM (SP-STM) and tunneling spin transport vector quantities, the longitudinal spin current and the spin transfer torque, are calculated in high spatial resolution within the same theoretical framework. A connection between the conventional charge current SP-STM image contrasts and the magnitudes of the spin transport vectors is demonstrated that enables the estimation of tunneling spin transport properties based on experimentally measured SP-STM images. A considerable tunability of the spin transport vectors by the involved spin polarizations is also highlighted. These possibilities and the combined theory of tunneling charge and vector spin transport pave the way for gaining deep insight into electric-current-induced tunneling spin transport properties in SP-STM and to the related dynamics of complex magnetic textures at surfaces.

  20. A practical method of predicting client revisit intention in a hospital setting.

    Science.gov (United States)

    Lee, Kyun Jick

    2005-01-01

    Data mining (DM) models are an alternative to traditional statistical methods for examining whether higher customer satisfaction leads to higher revisit intention. This study used a total of 906 outpatients' satisfaction data collected from a nationwide survey interviews conducted by professional interviewers on a face-to-face basis in South Korea, 1998. Analyses showed that the relationship between overall satisfaction with hospital services and outpatients' revisit intention, along with word-of-mouth recommendation as intermediate variables, developed into a nonlinear relationship. The five strongest predictors of revisit intention were overall satisfaction, intention to recommend to others, awareness of hospital promotion, satisfaction with physician's kindness, and satisfaction with treatment level.

  1. Design of PID temperature control system based on STM32

    Science.gov (United States)

    Zhang, Jianxin; Li, Hailin; Ma, Kai; Xue, Liang; Han, Bianhua; Dong, Yuemeng; Tan, Yue; Gu, Chengru

    2018-03-01

    A rapid and high-accuracy temperature control system was designed using proportional-integral-derivative (PID) control algorithm with STM32 as micro-controller unit (MCU). The temperature control system can be applied in the fields which have high requirements on the response speed and accuracy of temperature control. The temperature acquisition circuit in system adopted Pt1000 resistance thermometer as temperature sensor. Through this acquisition circuit, the monitoring actual temperature signal could be converted into voltage signal and transmitted into MCU. A TLP521-1 photoelectric coupler was matched with BD237 power transistor to drive the thermoelectric cooler (TEC) in FTA951 module. The effective electric power of TEC was controlled by the pulse width modulation (PWM) signals which generated by MCU. The PWM signal parameters could be adjusted timely by PID algorithm according to the difference between monitoring actual temperature and set temperature. The upper computer was used to input the set temperature and monitor the system running state via serial port. The application experiment results show that the temperature control system is featured by simple structure, rapid response speed, good stability and high temperature control accuracy with the error less than ±0.5°C.

  2. Interaction of gold with a pinwheel TiO similar to .sub.1,2./sub. film formed on Rh(111) facet: STM and DFT studies

    Czech Academy of Sciences Publication Activity Database

    Mutombo, Pingo; Gubo, R.; Berkó, A.

    2016-01-01

    Roč. 120, č. 23 (2016), s. 12917-12923 ISSN 1932-7447 Institutional support: RVO:68378271 Keywords : DFT * wheel-TiO ~1.2 ultrathin film * template * TiO 2 (110) * Rh(111) * Au * STM Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.536, year: 2016

  3. The reference ballistic imaging database revisited.

    Science.gov (United States)

    De Ceuster, Jan; Dujardin, Sylvain

    2015-03-01

    A reference ballistic image database (RBID) contains images of cartridge cases fired in firearms that are in circulation: a ballistic fingerprint database. The performance of an RBID was investigated a decade ago by De Kinder et al. using IBIS(®) Heritage™ technology. The results of that study were published in this journal, issue 214. Since then, technologies have evolved quite significantly and novel apparatus have become available on the market. The current research article investigates the efficiency of another automated ballistic imaging system, Evofinder(®) using the same database as used by De Kinder et al. The results demonstrate a significant increase in correlation efficiency: 38% of all matches were on first position of the Evofinder correlation list in comparison to IBIS(®) Heritage™ where only 19% were on the first position. Average correlation times are comparable to the IBIS(®) Heritage™ system. While Evofinder(®) demonstrates specific improvement for mutually correlating different ammunition brands, ammunition dependence of the markings is still strongly influencing the correlation result because the markings may vary considerably. As a consequence a great deal of potential hits (36%) was still far down in the correlation lists (positions 31 and lower). The large database was used to examine the probability of finding a match as a function of correlation list verification. As an example, the RBID study on Evofinder(®) demonstrates that to find at least 90% of all potential matches, at least 43% of the items in the database need to be compared on screen and this for breech face markings and firing pin impression separately. These results, although a clear improvement to the original RBID study, indicate that the implementation of such a database should still not be considered nowadays. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  4. Short segment myelitis as a first manifestation of neuromyelitis optica spectrum disorders.

    Science.gov (United States)

    Huh, So-Young; Kim, Su-Hyun; Hyun, Jae-Won; Jeong, In Hye; Park, Min Su; Lee, Sang-Hyun; Kim, Ho Jin

    2017-03-01

    Some patients with neuromyelitis optica spectrum disorders (NMOSD) present with spinal cord lesions extending fewer than three vertebral segments (short transverse myelitis, STM), hindering an early diagnosis. We investigated the frequency and imaging characteristics of STM lesions in patients presenting with myelitis as an initial manifestation of NMOSD. Patients seen at three referral hospitals in Korea between June 2005 and March 2015 who met the following inclusion criteria were recruited for review: seropositivity for aquaporin-4 antibody, initial presentation with myelitis and spinal cord magnetic resonance imaging (MRI) performed within 1 month of initial myelitis onset. Of the 76 enrolled patients, 65 (85.5%) collectively had 69 longitudinally extensive transverse myelitis lesions, while the remaining 11 (14.5%) had a total of 15 STM lesions. Of the 15 STM lesions, 5 spanned 2.5 vertebral segments, 6 were continuous over two segments, 3 showed a length of 1.5 segments and 1 was confined to a single segment. On axial imaging, all of the STM lesions involved the central grey matter. These MRI findings suggested that STM does not preclude the possibility of an NMOSD diagnosis.

  5. Variable-temperature independently driven four-tip scanning tunneling microscope

    International Nuclear Information System (INIS)

    Hobara, Rei; Nagamura, Naoka; Hasegawa, Shuji; Matsuda, Iwao; Yamamoto, Yuko; Miyatake, Yutaka; Nagamura, Toshihiko

    2007-01-01

    The authors have developed an ultrahigh vacuum (UHV) variable-temperature four-tip scanning tunneling microscope (STM), operating from room temperature down to 7 K, combined with a scanning electron microscope (SEM). Four STM tips are mechanically and electrically independent and capable of positioning in arbitrary configurations in nanometer precision. An integrated controller system for both of the multitip STM and SEM with a single computer has also been developed, which enables the four tips to operate either for STM imaging independently and for four-point probe (4PP) conductivity measurements cooperatively. Atomic-resolution STM images of graphite were obtained simultaneously by the four tips. Conductivity measurements by 4PP method were also performed at various temperatures with the four tips in square arrangement with direct contact to the sample surface

  6. Thermomyces lanuginosus STm: a source of thermostable hydrolytic enzymes for novel application in extraction of high-quality natural rubber from Taraxacum kok-saghyz (rubber dandelion)

    Science.gov (United States)

    Hydrolytic enzymes from a newly isolated strain of the thermophilic fungus Thermomyces lanuginosus were used to extract rubber from Taraxacum kok-saghyz commonly known as rubber (or Russian or Kazak(h)) dandelion. The fungus was isolated from garden soil and identified as Thermomyces lanuginosus STm...

  7. Time-resolved scanning tunnelling microscopy

    NARCIS (Netherlands)

    van Houselt, Arie; Zandvliet, Henricus J.W.

    2010-01-01

    Scanning tunneling microscopy has revolutionized our ability to image, study, and manipulate solid surfaces on the size scale of atoms. One important limitation of the scanning tunneling microscope (STM) is, however, its poor time resolution. Recording a standard image with a STM typically takes

  8. The Faraday effect revisited: General theory

    DEFF Research Database (Denmark)

    Cornean, Horia Decebal; Nenciu, Gheorghe; Pedersen, Thomas Garm

    This paper is the first in a series revisiting the Faraday effect, or more generally, the theory of electronic quantum transport/optical response in bulk media in the presence of a constant magnetic field. The independent electron approximation is assumed. For free electrons, the transverse...

  9. Theory of high-resolution tunneling spin transport on a magnetic skyrmion

    OpenAIRE

    Palotás, Krisztián; Rózsa, Levente; Szunyogh, László

    2018-01-01

    Tunneling spin transport characteristics of a magnetic skyrmion are described theoretically in magnetic scanning tunneling microscopy (STM). The spin-polarized charge current in STM (SP-STM) and tunneling spin transport vector quantities, the longitudinal spin current and the spin transfer torque are calculated in high spatial resolution within the same theoretical framework. A connection between the conventional charge current SP-STM image contrasts and the magnitudes of the spin transport v...

  10. Revisiting the inelastic electron tunneling spectroscopy of single hydrogen atom adsorbed on the Cu(100) surface

    International Nuclear Information System (INIS)

    Jiang, Zhuoling; Wang, Hao; Sanvito, Stefano; Hou, Shimin

    2015-01-01

    Inelastic electron tunneling spectroscopy (IETS) of a single hydrogen atom on the Cu(100) surface in a scanning tunneling microscopy (STM) configuration has been investigated by employing the non-equilibrium Green’s function formalism combined with density functional theory. The electron-vibration interaction is treated at the level of lowest order expansion. Our calculations show that the single peak observed in the previous STM-IETS experiments is dominated by the perpendicular mode of the adsorbed H atom, while the parallel one only makes a negligible contribution even when the STM tip is laterally displaced from the top position of the H atom. This propensity of the IETS is deeply rooted in the symmetry of the vibrational modes and the characteristics of the conduction channel of the Cu-H-Cu tunneling junction, which is mainly composed of the 4s and 4p z atomic orbitals of the Cu apex atom and the 1s orbital of the adsorbed H atom. These findings are helpful for deepening our understanding of the propensity rules for IETS and promoting IETS as a more popular spectroscopic tool for molecular devices

  11. Who should do the dishes now? Revisiting gender and housework in contemporary urban South Wales

    OpenAIRE

    Mannay, Dawn

    2016-01-01

    This chapter revisits Jane Pilcher’s (1994) seminal work ‘Who should do the dishes? Three generations of Welsh women talking about men and housework’, which was originally published in Our Sister’s Land: the changing identities of women in Wales. As discussed in the introductory chapter, I began revisiting classic Welsh studies as part of my doctoral study Mothers and daughters on the margins: gender, generation and education (Mannay, 2012); this lead to the later publication of a revisiting ...

  12. Adsorption of the ionic liquid [BMP][TFSA] on Au(111 and Ag(111: substrate effects on the structure formation investigated by STM

    Directory of Open Access Journals (Sweden)

    Benedikt Uhl

    2013-12-01

    Full Text Available In order to resolve substrate effects on the adlayer structure and structure formation and on the substrate–adsorbate and adsorbate–adsorbate interactions, we investigated the adsorption of thin films of the ionic liquid (IL 1-butyl-1-methylpyrrolidinium-bis(trifluoromethylsulfonylimide [BMP][TFSA] on the close-packed Ag(111 and Au(111 surfaces by scanning tunneling microscopy, under ultra high vacuum (UHV conditions in the temperature range between about 100 K and 293 K. At room temperature, highly mobile 2D liquid adsorbate phases were observed on both surfaces. At low temperatures, around 100 K, different adsorbed IL phases were found to coexist on these surfaces, both on silver and gold: a long-range ordered (‘2D crystalline’ phase and a short-range ordered (‘2D glass’ phase. Both phases exhibit different characteristics on the two surfaces. On Au(111, the surface reconstruction plays a major role in the structure formation of the 2D crystalline phase. In combination with recent density functional theory calculations, the sub-molecularly resolved STM images allow to clearly discriminate between the [BMP]+ cation and [TFSA]− anion.

  13. The Faraday effect revisited: General theory

    DEFF Research Database (Denmark)

    Cornean, Horia Decebal; Nenciu, Gheorghe; Pedersen, Thomas Garm

    2006-01-01

    This paper is the first in a series revisiting the Faraday effect, or more generally, the theory of electronic quantum transport/optical response in bulk media in the presence of a constant magnetic field. The independent electron approximation is assumed. At zero temperature and zero frequency...

  14. Bayesian spatial transformation models with applications in neuroimaging data.

    Science.gov (United States)

    Miranda, Michelle F; Zhu, Hongtu; Ibrahim, Joseph G

    2013-12-01

    The aim of this article is to develop a class of spatial transformation models (STM) to spatially model the varying association between imaging measures in a three-dimensional (3D) volume (or 2D surface) and a set of covariates. The proposed STM include a varying Box-Cox transformation model for dealing with the issue of non-Gaussian distributed imaging data and a Gaussian Markov random field model for incorporating spatial smoothness of the imaging data. Posterior computation proceeds via an efficient Markov chain Monte Carlo algorithm. Simulations and real data analysis demonstrate that the STM significantly outperforms the voxel-wise linear model with Gaussian noise in recovering meaningful geometric patterns. Our STM is able to reveal important brain regions with morphological changes in children with attention deficit hyperactivity disorder. © 2013, The International Biometric Society.

  15. Combining scanning tunneling microscopy and synchrotron radiation for high-resolution imaging and spectroscopy with chemical, electronic, and magnetic contrast

    International Nuclear Information System (INIS)

    Cummings, M.L.; Chien, T.Y.; Preissner, C.; Madhavan, V.; Diesing, D.; Bode, M.; Freeland, J.W.; Rose, V.

    2012-01-01

    The combination of high-brilliance synchrotron radiation with scanning tunneling microscopy opens the path to high-resolution imaging with chemical, electronic, and magnetic contrast. Here, the design and experimental results of an in-situ synchrotron enhanced x-ray scanning tunneling microscope (SXSTM) system are presented. The system is designed to allow monochromatic synchrotron radiation to enter the chamber, illuminating the sample with x-ray radiation, while an insulator-coated tip (metallic tip apex open for tunneling, electron collection) is scanned over the surface. A unique feature of the SXSTM is the STM mount assembly, designed with a two free-flex pivot, providing an angular degree of freedom for the alignment of the tip and sample with respect to the incoming x-ray beam. The system designed successfully demonstrates the ability to resolve atomic-scale corrugations. In addition, experiments with synchrotron x-ray radiation validate the SXSTM system as an accurate analysis technique for the study of local magnetic and chemical properties on sample surfaces. The SXSTM system's capabilities have the potential to broaden and deepen the general understanding of surface phenomena by adding elemental contrast to the high-resolution of STM. -- Highlights: ► Synchrotron enhanced x-ray scanning tunneling microscope (SXSTM) system designed. ► Unique STM mount design allows angular DOF for tip alignment with x-ray beam. ► System demonstrates ability to resolve atomic corrugations on HOPG. ► Studies show chemical sensitivity with STM tip from photocurrent and tunneling. ► Results show system's ability to study local magnetic (XMCD) properties on Fe films.

  16. STM and transport measurements of highly charged ion modified materials

    International Nuclear Information System (INIS)

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

    2007-01-01

    Careful measurements of highly charged ions (HCIs) colliding with gases and surfaces have provided glimpses of intense electronic interactions, but a comprehensive model for the interaction mechanisms, time scales, and resultant nano-features that bridges materials systems is yet to be realized. At the National Institute of Standards and Technology (NIST) electron beam ion trap (EBIT) facility, new apparatus is now connected to the HCI beamline to allow preparation of clean, atomically flat surfaces of single crystals, e.g. gold, tungsten and silicon, and deposition and patterning of thin films, e.g. high resistivity oxides, ferromagnetic metals, normal metals and superconductors. Experiments reported here focus on the electronic and morphological structure of HCI induced nano-features. Current activities are focused on using in situ scanning tunneling microscope (STM) on Au(1 1 1) and (separately) ex situ transport measurements to study electronic properties within HCI modified magnetic multilayer systems. Specifically, we are fabricating magnetic multilayers similar to magnetic tunnel junctions (MTJs) (important in advanced magnetic field sensors and superconducting Josephson junction devices) and using HCIs to adjust critical electronic properties. The electrical response of the tunnel junction to HCIs provides a novel approach to performing HCI-induced nanostructure ensemble measurements

  17. Development of a scanning tunneling microscope combined with a synchrotron radiation light source

    International Nuclear Information System (INIS)

    Hasegawa, Yukio; Okuda, Taichi; Eguchi, Toyoaki; Matsushima, Takeshi; Harasawa, Ayumi; Akiyama, Kotone; Kinoshita, Toyohiko

    2005-01-01

    We have developed a scanning tunneling microscope (STM) combined with a synchrotron-radiation light source (SR-STM) aiming at elemental analysis in a spatial resolution of STM. Using SR-STM atomically resolved STM images under the irradiation and also X-ray adsorption spectra clearly showing an adsorption edge of a substrate were successfully obtained by detecting photo-emitted electrons with the STM tip. In order to focus the probing area of the photo-induced current, a glass-coated metal tip sharpened with focused ion beam was used as a probe. The present situation and prospects of the instrument are discussed in this review. (author)

  18. Oxygen vacancies on TiO2(110) and their interaction with H2O and O2: A combined high-resolution STM and DFT study

    DEFF Research Database (Denmark)

    Wendt, Stefan; Schaub, Renald; Matthiesen, Jesper

    2005-01-01

    From an interplay between high-resolution scanning tunneling microscopy (STM) and density functional theory (DFT) we discuss the origin of various point defects on reduced rutile TiO2(110)–(1 × 1) surfaces. By means of adsorption and desorption experiments using water and oxygen as probe molecules...

  19. Ultrahigh vacuum STM/STS studies of the Bi-O surface in Bi2Sr2CuOy single crystals

    International Nuclear Information System (INIS)

    Ikeda, Kazuto; Tomeno, Izumi; Takamuku, Kenshi; Yamaguchi, Koji; Itti, Rittaporn; Koshizuka, Naoki

    1992-01-01

    Scanning tunneling microscopic and spectroscopic studies were made on cleaved surfaces of Bi 2 Sr 2 CuO y single crystals using an ultrahigh-vacuum scanning tunneling microscope (UHV-STM). The modulation structures of the Bi-O surface were observed at room temperature with atomic resolution. The tunneling spectra showed electronic gap structures similar to those observed for the Bi-O surface of superconducting Bi-2212 single crystals. This suggests that superconductivity is not directly related to the electronic structure observed in the Bi-O plane. (orig.)

  20. Response to "Critical Assessment of the Evidence for Striped Nanoparticles".

    Directory of Open Access Journals (Sweden)

    Quy Khac Ong

    Full Text Available Stirling et al., (10.1371/journal.pone.0108482 presented an analysis on some of our publications on the formation of stripe-like domains on mixed-ligand coated gold nanoparticles. The authors shed doubts on some of our results however no valid argument is provided against what we have shown since our first publication: scanning tunneling microscopy (STM images of striped nanoparticles show stripe-like domains that are independent of imaging parameters and in particular of imaging speed. We have consistently ruled out the presence of artifacts by comparing sets of images acquired at different tip speeds, finding invariance of the stipe-like domains. Stirling and co-workers incorrectly analyzed this key control, using a different microscope and imaging conditions that do not compare to ours. We show here data proving that our approach is rigorous. Furthermore, we never solely relied on image analysis to draw our conclusions; we have always used the chemical nature of the particles to assess the veracity of our images. Stirling et al. do not provide any justification for the spacing of the features that we find on nanoparticles: ~1 nm for mixed ligand particles and ~ 0.5 nm for homoligand particles. Hence our two central arguments remain unmodified: independence from imaging parameters and dependence on ligand shell chemical composition. The paper report observations on our STM images; none is a sufficient condition to prove that our images are artifacts. We thoroughly addressed issues related to STM artifacts throughout our microscopy work. Stirling et al. provide guidelines for what they consider good STM images of nanoparticles, such images are indeed present in our literature. They conclude that the evidences we provided to date are insufficient, this is a departure from one of the authors' previous article which concluded that our images were composed of artifacts. Given that four independent laboratories have reproduced our measurements and

  1. Deterministic Graphical Games Revisited

    DEFF Research Database (Denmark)

    Andersson, Daniel; Hansen, Kristoffer Arnsfelt; Miltersen, Peter Bro

    2008-01-01

    We revisit the deterministic graphical games of Washburn. A deterministic graphical game can be described as a simple stochastic game (a notion due to Anne Condon), except that we allow arbitrary real payoffs but disallow moves of chance. We study the complexity of solving deterministic graphical...... games and obtain an almost-linear time comparison-based algorithm for computing an equilibrium of such a game. The existence of a linear time comparison-based algorithm remains an open problem....

  2. Atom-resolved surface chemistry using scanning tunneling microscopy (STM) and spectroscopy (STS)

    International Nuclear Information System (INIS)

    Avouris, P.

    1989-01-01

    The author shows that by using STM and STS one can study chemistry with atomic resolution. The author uses two examples: the reaction of Si(111)-(7x7) with (a) NH 3 and (b) decaborane (DB). In case (a) the authors can directly observe the spatial distribution of the reaction. He determined which surface atoms have reacted and how the products of the reaction are distributed. He found that the different dangling-bond sites have significantly different reactivities and explain these differences in terms of the local electronic structure. In case (b) the 7x7 reconstruction is eliminated and at high temperatures, (√3 x √3) R30 degree reconstructions are observed. Depending on the amount of DB and the annealing temperature the √3 structures contain variable numbers of B and Si adatoms on T 4 -sites. Calculations show that the structure involving B adatoms, although kinetically favored, is not the lowest energy configuration. The lowest energy state involves B in a substitutional site under a Si adatom

  3. Applicability of Socio-Technical Model (STM in Working System of Modern Organizations

    Directory of Open Access Journals (Sweden)

    Rosmaini Tasmin

    2011-10-01

    Full Text Available Knowledge has been identified as one of the most important resources in organization that contributes to competitive advantages. Organizations around the world realize and put into practice an approach that bases on technological and sociological aspects to fill-up the gaps in their workplaces. The Socio-Technical Model (STM is an established organizational model introduced by Trist since 1960s at Tavistock Institute, London. It relates two most common components exist in all organizations, namely social systems (human and technological systems (information technology, machinery and equipment in organizations over many decades. This paper reviews the socio-technical model from various perspectives of its developmental stages and ideas written by researchers. Therefore, several literature reviews on socio-technical model have been compiled and discussed to justify whether its basic argument matches with required practices in Techno-Social environments. Through a socio-technical perspective on Knowledge Management, this paper highlights the interplay between social systems and technological system. It also suggests that management and leadership play critical roles in establishing the techno-social perspective for the effective assimilation of Knowledge Management practices.

  4. Direct formation of a polyamide on Ag(111): Joint XPS and STM studies

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, Martin; Steinrueck, Hans-Peter; Gottfried, J. Michael [Lehrstuhl fuer Physikalische Chemie II, Universitaet Erlangen-Nuernberg (Germany); Schmitz, Christoph H.; Ikonomov, Julian; Sokolowski, Moritz [Institut fuer Physikalische und Theoretische Chemie, Universitaet Bonn (Germany)

    2011-07-01

    The polymer poly(p-phenylene terephthalamide) (PPTA) was synthesized on Ag(111) by co-adsorption of the reactive monomer compounds terephthaloyl chloride (TPC) and p-phenylenediamine (PPD) at 300 K. The resulting adsorbate phases were characterised by photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). A detailed study of the chemical composition and morphology revealed a complex reaction mechanism, by which the formation of amide bonds leads to folded PPTA polymer chains. According to XPS, the chloride of the TPC precursor is not released as HCl as in the bulk reaction, but remains on the surface as chemisorbed Cl or AgCl. Further temperature-programmed XPS studies of pure TPC on Ag(111) reveal that the molecule decomposes already above 130 K, forming chemisorbed Cl (or AgCl) and a phenylene-dicarbonyl species, which is presumably stabilized by the substrate. The adsorbed chlorine partially desorbs above 800 K as molecular AgCl.

  5. The Sentinel-3 Surface Topography Mission (S-3 STM): Level 2 SAR Ocean Retracker

    Science.gov (United States)

    Dinardo, S.; Lucas, B.; Benveniste, J.

    2015-12-01

    The SRAL Radar Altimeter, on board of the ESA Mission Sentinel-3 (S-3), has the capacity to operate either in the Pulse-Limited Mode (also known as LRM) or in the novel Synthetic Aperture Radar (SAR) mode. Thanks to the initial results from SAR Altimetry obtained exploiting CryoSat-2 data, lately the interest by the scientific community in this new technology has significantly increased and consequently the definition of accurate processing methodologies (along with validation strategies) has now assumed a capital importance. In this paper, we present the algorithm proposed to retrieve from S-3 STM SAR return waveforms the standard ocean geophysical parameters (ocean topography, wave height and sigma nought) and the validation results that have been so far achieved exploiting the CryoSat-2 data as well as the simulated data. The inversion method (retracking) to extract from the return waveform the geophysical information is a curve best-fitting scheme based on the bounded Levenberg-Marquardt Least-Squares Estimation Method (LEVMAR-LSE). The S-3 STM SAR Ocean retracking algorithm adopts, as return waveform’s model, the “SAMOSA” model [Ray et al, 2014], named after the R&D project SAMOSA (led by Satoc and funded by ESA), in which it has been initially developed. The SAMOSA model is a physically-based model that offers a complete description of a SAR Altimeter return waveform from ocean surface, expressed in the form of maps of reflected power in Delay-Doppler space (also known as stack) or expressed as multilooked echoes. SAMOSA is able to account for an elliptical antenna pattern, mispointing errors in roll and yaw, surface scattering pattern, non-linear ocean wave statistics and spherical Earth surface effects. In spite of its truly comprehensive character, the SAMOSA model comes with a compact analytical formulation expressed in term of Modified Bessel functions. The specifications of the retracking algorithm have been gathered in a technical document (DPM

  6. Revisiting Hansen Solubility Parameters by Including Thermodynamics

    NARCIS (Netherlands)

    Louwerse, Manuel J; Fernández-Maldonado, Ana María; Rousseau, Simon; Moreau-Masselon, Chloe; Roux, Bernard; Rothenberg, Gadi

    2017-01-01

    The Hansen solubility parameter approach is revisited by implementing the thermodynamics of dissolution and mixing. Hansen's pragmatic approach has earned its spurs in predicting solvents for polymer solutions, but for molecular solutes improvements are needed. By going into the details of entropy

  7. Bottomonium spectrum revisited

    CERN Document Server

    Segovia, Jorge; Entem, David R.; Fernández, Francisco

    2016-01-01

    We revisit the bottomonium spectrum motivated by the recently exciting experimental progress in the observation of new bottomonium states, both conventional and unconventional. Our framework is a nonrelativistic constituent quark model which has been applied to a wide range of hadronic observables from the light to the heavy quark sector and thus the model parameters are completely constrained. Beyond the spectrum, we provide a large number of electromagnetic, strong and hadronic decays in order to discuss the quark content of the bottomonium states and give more insights about the better way to determine their properties experimentally.

  8. Hospital revisit rate after a diagnosis of conversion disorder.

    Science.gov (United States)

    Merkler, Alexander E; Parikh, Neal S; Chaudhry, Simriti; Chait, Alanna; Allen, Nicole C; Navi, Babak B; Kamel, Hooman

    2016-04-01

    To estimate the hospital revisit rate of patients diagnosed with conversion disorder (CD). Using administrative data, we identified all patients discharged from California, Florida and New York emergency departments (EDs) and acute care hospitals between 2005 and 2011 with a primary discharge diagnosis of CD. Patients discharged with a primary diagnosis of seizure or transient global amnesia (TGA) served as control groups. Our primary outcome was the rate of repeat ED visits and hospital admissions after initial presentation. Poisson regression was used to compare rates between diagnosis groups while adjusting for demographic characteristics. We identified 7946 patients discharged with a primary diagnosis of CD. During a mean follow-up of 3.0 (±1.6) years, patients with CD had a median of three (IQR, 1-9) ED or inpatient revisits, compared with 0 (IQR, 0-2) in patients with TGA and 3 (IQR, 1-7) in those with seizures. Revisit rates were 18.25 (95% CI, 18.10 to 18.40) visits per 100 patients per month in those with CD, 3.90 (95% CI, 3.84 to 3.95) in those with TGA and 17.78 (95% CI, 17.75 to 17.81) in those with seizures. As compared to CD, the incidence rate ratio for repeat ED visits or hospitalisations was 0.89 (95% CI, 0.86 to 0.93) for seizure disorder and 0.32 (95% CI 0.31 to 0.34) for TGA. CD is associated with a substantial hospital revisit rate. Our findings suggest that CD is not an acute, time-limited response to stress, but rather that CD is a manifestation of a broader pattern of chronic neuropsychiatric disease. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  9. The Future of Engineering Education--Revisited

    Science.gov (United States)

    Wankat, Phillip C.; Bullard, Lisa G.

    2016-01-01

    This paper revisits the landmark CEE series, "The Future of Engineering Education," published in 2000 (available free in the CEE archives on the internet) to examine the predictions made in the original paper as well as the tools and approaches documented. Most of the advice offered in the original series remains current. Despite new…

  10. Atomic geometry and STM simulations of a TiO.sub.2./sub.(110) surface upon formation of an oxygen vacancy and hydroxyl group

    Czech Academy of Sciences Publication Activity Database

    Mutombo, Pingo; Kiss, A.M.; Berkó, A.; Cháb, Vladimír

    2008-01-01

    Roč. 16, - (2008), 025007/1-025007/9 ISSN 0965-0393 R&D Projects: GA AV ČR IAA1010413 Grant - others:MŠMT(CZ) 9/2004 KONTAKT Institutional research plan: CEZ:AV0Z10100521 Source of funding: V - iné verejné zdroje Keywords : vacance * Oxygen * OH group * STM Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.388, year: 2008

  11. A scanning tunneling microscope capable of imaging specified micron-scale small samples

    Science.gov (United States)

    Tao, Wei; Cao, Yufei; Wang, Huafeng; Wang, Kaiyou; Lu, Qingyou

    2012-12-01

    We present a home-built scanning tunneling microscope (STM) which allows us to precisely position the tip on any specified small sample or sample feature of micron scale. The core structure is a stand-alone soft junction mechanical loop (SJML), in which a small piezoelectric tube scanner is mounted on a sliding piece and a "U"-like soft spring strip has its one end fixed to the sliding piece and its opposite end holding the tip pointing to the sample on the scanner. Here, the tip can be precisely aligned to a specified small sample of micron scale by adjusting the position of the spring-clamped sample on the scanner in the field of view of an optical microscope. The aligned SJML can be transferred to a piezoelectric inertial motor for coarse approach, during which the U-spring is pushed towards the sample, causing the tip to approach the pre-aligned small sample. We have successfully approached a hand cut tip that was made from 0.1 mm thin Pt/Ir wire to an isolated individual 32.5 × 32.5 μm2 graphite flake. Good atomic resolution images and high quality tunneling current spectra for that specified tiny flake are obtained in ambient conditions with high repeatability within one month showing high and long term stability of the new STM structure. In addition, frequency spectra of the tunneling current signals do not show outstanding tip mount related resonant frequency (low frequency), which further confirms the stability of the STM structure.

  12. A scanning tunneling microscope capable of imaging specified micron-scale small samples.

    Science.gov (United States)

    Tao, Wei; Cao, Yufei; Wang, Huafeng; Wang, Kaiyou; Lu, Qingyou

    2012-12-01

    We present a home-built scanning tunneling microscope (STM) which allows us to precisely position the tip on any specified small sample or sample feature of micron scale. The core structure is a stand-alone soft junction mechanical loop (SJML), in which a small piezoelectric tube scanner is mounted on a sliding piece and a "U"-like soft spring strip has its one end fixed to the sliding piece and its opposite end holding the tip pointing to the sample on the scanner. Here, the tip can be precisely aligned to a specified small sample of micron scale by adjusting the position of the spring-clamped sample on the scanner in the field of view of an optical microscope. The aligned SJML can be transferred to a piezoelectric inertial motor for coarse approach, during which the U-spring is pushed towards the sample, causing the tip to approach the pre-aligned small sample. We have successfully approached a hand cut tip that was made from 0.1 mm thin Pt∕Ir wire to an isolated individual 32.5 × 32.5 μm(2) graphite flake. Good atomic resolution images and high quality tunneling current spectra for that specified tiny flake are obtained in ambient conditions with high repeatability within one month showing high and long term stability of the new STM structure. In addition, frequency spectra of the tunneling current signals do not show outstanding tip mount related resonant frequency (low frequency), which further confirms the stability of the STM structure.

  13. [Research on the High Efficiency Data Communication Repeater Based on STM32F103].

    Science.gov (United States)

    Zhang, Yahui; Li, Zheng; Chen, Guangfei

    2015-11-01

    To improve the radio frequency (RF) transmission distance of the wireless terminal of the medical internet of things (LOT), to realize the real-time and efficient data communication, the intelligent relay system based on STM32F103 single chip microcomputer (SCM) is proposed. The system used nRF905 chip to achieve the collection, of medical and health information of patients in the 433 MHz band, used SCM to control the serial port to Wi-Fi module to transmit information from 433 MHz to 2.4 GHz wireless Wi-Fi band, and used table look-up algorithm of ready list to improve the efficiency of data communications. The design can realize real-time and efficient data communication. The relay which is easy to use with high practical value can extend the distance and mode of data transmission and achieve real-time transmission of data.

  14. Study of sulfur adlayers on Au(1 1 1) from basic hydrolysis of piperazine bis(dithiocarbamate) sodium salt

    International Nuclear Information System (INIS)

    Martínez, Javier A.; Valenzuela, José; Hernandez-Tamargo, Carlos E.; Cao-Milán, Roberto; Herrera, José A.; Díaz, Jesús A.; Farías, Mario H.; Mikosch, Hans

    2015-01-01

    Highlights: • S adlayer formation from descomposition of piperazine bis(dithiocarbamate) sodium salt under alkaline conditions. • Quasi-rectangular octomers (eight sulfur atoms) coexist with another phase. • A DFT surface model of four S-dimers arranged as octomers reproduced real STM images. - Abstract: Sulfur adlayers on Au(1 1 1) were obtained after the interaction of a gold substrate with an alkaline solution of piperazine bis(dithiocarbamate) sodium salt. Characterization of the sulfur modified gold surface was performed by means of X-Ray Photoelectron Spectroscopy (XPS), Scanning Tunneling Microscopy (STM) and Density Functional Theory (DFT) calculations. XPS signals indicated the presence of S–Au bonds, monomeric and polymeric sulfur, and absence of nitrogen and sodium. Images from STM showed the formation of quasi-rectangular octomers in coexistence with another phase. A DFT model using the arrangement of sulfur dimers on the Au(1 1 1) surface effectively reproduced the experimental STM images

  15. Study of sulfur adlayers on Au(1 1 1) from basic hydrolysis of piperazine bis(dithiocarbamate) sodium salt

    Energy Technology Data Exchange (ETDEWEB)

    Martínez, Javier A. [Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana, Zapata y G, El Vedado, Plaza de la Revolución, La Habana 10400 (Cuba); Valenzuela, José [Centro de Nanociencias y Nanotecnología (CNyN), Universidad Nacional Autónoma de México (UNAM), km 107 Carretera Tijuana-Ensenada, Ensenada, BC 22860 (Mexico); Hernandez-Tamargo, Carlos E. [Laboratorio de Química Computacional y Teórica (LQCT), Facultad de Química, Universidad de La Habana, Zapata y G, El Vedado, Plaza de la Revolución, La Habana 10400 (Cuba); Cao-Milán, Roberto [Laboratorio de Bioinorgánica (LBI), Facultad de Química, Universidad de La Habana, Zapata y G, El Vedado, Plaza de la Revolución, La Habana 10400 (Cuba); Herrera, José A. [Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana, Zapata y G, El Vedado, Plaza de la Revolución, La Habana 10400 (Cuba); Díaz, Jesús A.; Farías, Mario H. [Centro de Nanociencias y Nanotecnología (CNyN), Universidad Nacional Autónoma de México (UNAM), km 107 Carretera Tijuana-Ensenada, Ensenada, BC 22860 (Mexico); Mikosch, Hans [Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/E164-EC, 1060 Vienna (Austria); and others

    2015-08-01

    Highlights: • S adlayer formation from descomposition of piperazine bis(dithiocarbamate) sodium salt under alkaline conditions. • Quasi-rectangular octomers (eight sulfur atoms) coexist with another phase. • A DFT surface model of four S-dimers arranged as octomers reproduced real STM images. - Abstract: Sulfur adlayers on Au(1 1 1) were obtained after the interaction of a gold substrate with an alkaline solution of piperazine bis(dithiocarbamate) sodium salt. Characterization of the sulfur modified gold surface was performed by means of X-Ray Photoelectron Spectroscopy (XPS), Scanning Tunneling Microscopy (STM) and Density Functional Theory (DFT) calculations. XPS signals indicated the presence of S–Au bonds, monomeric and polymeric sulfur, and absence of nitrogen and sodium. Images from STM showed the formation of quasi-rectangular octomers in coexistence with another phase. A DFT model using the arrangement of sulfur dimers on the Au(1 1 1) surface effectively reproduced the experimental STM images.

  16. Revisiting Weak Simulation for Substochastic Markov Chains

    DEFF Research Database (Denmark)

    Jansen, David N.; Song, Lei; Zhang, Lijun

    2013-01-01

    of the logic PCTL\\x, and its completeness was conjectured. We revisit this result and show that soundness does not hold in general, but only for Markov chains without divergence. It is refuted for some systems with substochastic distributions. Moreover, we provide a counterexample to completeness...

  17. STM and x-ray diffraction temperature-dependent growth study of SrRuO{sub 3} PLD thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hawley, M.E.; Jia, Q.X.; Brown, G.W.

    1996-12-31

    SrRuO{sub 3} (SRO) has recently found a number of applications in different fields, e.g. as a buffer layer for the growth of high temperature superconductor (HTS) YBa{sub 2}Cu{sub 3}O{sub 7-x} films and as a bottom electrode for ferroelectric or high dielectric constant thin film capacitors and nonvolatile data storage. The growth of high crystallinity SRO films with good structural and electrical properties is the prerequisite for each of these applications. In this paper we describe the affect of one growth parameters temperature (T), on the crystalline quality, epitaxial substrate relationship and resulting electrical properties. SRO films were deposited on LaAlO{sub 3} single crystal substrates by pulsed laser deposition at substrate temperatures (T{sub s}) ranging from room temperature (RT) up to 800{degrees}C with a nominal film thickness of 150 nm range. The resulting films were characterized by x-ray diffraction, 4-point transport, and STM. The films` microstructures, as revealed by STM, evolved from polygranular at RT to a layered plate-like structure at higher deposition temperatures, T{sub s}, Increasing T{sub s} was marked first by increasing grain size, then a stronger orientational relationship between film and substrate, finally followed by the development of increased connectivity between grains to an extended island or condensed layered state. The transition from polygranular to layered structure occurred at T{sub s} > 650{degrees}C. Increased conductivity paralleled the changes in microstructure. The surfaces of all of the films were relatively smooth; the oriented films are suitable for use as conductive templates in multilayer structures.

  18. Stereospecificity of oligonucleotide interactions revisited: no evidence for heterochiral hybridization and ribozyme/DNAzyme activity.

    Directory of Open Access Journals (Sweden)

    Kai Hoehlig

    Full Text Available A major challenge for the application of RNA- or DNA-oligonucleotides in biotechnology and molecular medicine is their susceptibility to abundant nucleases. One intriguing possibility to tackle this problem is the use of mirror-image (l-oligonucleotides. For aptamers, this concept has successfully been applied to even develop therapeutic agents, so-called Spiegelmers. However, for technologies depending on RNA/RNA or RNA/DNA hybridization, like antisense or RNA interference, it has not been possible to use mirror-image oligonucleotides because Watson-Crick base pairing of complementary strands is (thought to be stereospecific. Many scientists consider this a general principle if not a dogma. A recent publication proposing heterochiral Watson-Crick base pairing and sequence-specific hydrolysis of natural RNA by mirror-image ribozymes or DNAzymes (and vice versa prompted us to systematically revisit the stereospecificity of oligonucleotides hybridization and catalytic activity. Using hyperchromicity measurements we demonstrate that hybridization only occurs among homochiral anti-parallel complementary oligonucleotide strands. As expected, achiral PNA hybridizes to RNA and DNA irrespective of their chirality. In functional assays we could not confirm an alleged heterochiral hydrolytic activity of ribozymes or DNAzymes. Our results confirm a strict stereospecificity of oligonucleotide hybridization and clearly argue against the possibility to use mirror-image oligonucleotides for gene silencing or antisense applications.

  19. Revisiting the formal foundation of Probabilistic Databases

    NARCIS (Netherlands)

    Wanders, B.; van Keulen, Maurice

    2015-01-01

    One of the core problems in soft computing is dealing with uncertainty in data. In this paper, we revisit the formal foundation of a class of probabilistic databases with the purpose to (1) obtain data model independence, (2) separate metadata on uncertainty and probabilities from the raw data, (3)

  20. Scanning Tunneling Microscopy Evidence for the Dissociation of Carbon Monoxide on Ruthenium Steps

    DEFF Research Database (Denmark)

    Tison, Yann; Nielsen, Kenneth; Mowbray, Duncan J.

    2012-01-01

    –Tropsch processes under certain conditions, has been debated for years. Here, scanning tunneling microscopy (STM) and density functional theory (DFT) are used to clarify the role of monatomic steps in the splitting of CO on a stepped Ru(0 1 54) crystal, which displays alternating steps with either 4-fold or 3-fold...... symmetry. After CO doses at elevated temperatures, the STM images reveal step decorations characteristic of atomic oxygen resulting from CO dissociation on every second step. The comparison of the STM images with the results of DFT calculations shows that the step decoration occurs on the steps displaying...

  1. Revisiting Mutual Fund Performance Evaluation

    OpenAIRE

    Angelidis, Timotheos; Giamouridis, Daniel; Tessaromatis, Nikolaos

    2012-01-01

    Mutual fund manager excess performance should be measured relative to their self-reported benchmark rather than the return of a passive portfolio with the same risk characteristics. Ignoring the self-reported benchmark introduces biases in the measurement of stock selection and timing components of excess performance. We revisit baseline empirical evidence in mutual fund performance evaluation utilizing stock selection and timing measures that address these biases. We introduce a new factor e...

  2. Deterministic Graphical Games Revisited

    DEFF Research Database (Denmark)

    Andersson, Klas Olof Daniel; Hansen, Kristoffer Arnsfelt; Miltersen, Peter Bro

    2012-01-01

    Starting from Zermelo’s classical formal treatment of chess, we trace through history the analysis of two-player win/lose/draw games with perfect information and potentially infinite play. Such chess-like games have appeared in many different research communities, and methods for solving them......, such as retrograde analysis, have been rediscovered independently. We then revisit Washburn’s deterministic graphical games (DGGs), a natural generalization of chess-like games to arbitrary zero-sum payoffs. We study the complexity of solving DGGs and obtain an almost-linear time comparison-based algorithm...

  3. Metamorphosis in Craniiformea revisited

    DEFF Research Database (Denmark)

    Altenburger, Andreas; Wanninger, Andreas; Holmer, Lars E.

    2013-01-01

    We revisited the brachiopod fold hypothesis and investigated metamorphosis in the craniiform brachiopod Novocrania anomala. Larval development is lecithotrophic and the dorsal (brachial) valve is secreted by dorsal epithelia. We found that the juvenile ventral valve, which consists only of a thin...... brachiopods during metamorphosis to cement their pedicle to the substrate. N. anomala is therefore not initially attached by a valve but by material corresponding to pedicle cuticle. This is different to previous descriptions, which had led to speculations about a folding event in the evolution of Brachiopoda...

  4. From Graphite to Graphene via Scanning Tunneling Microscopy

    Science.gov (United States)

    Qi, Dejun

    The primary objective of this dissertation is to study both graphene on graphite and pristine freestanding grapheme using scanning tunneling microscopy (STM) and density functional theory (DFT) simulation technique. In the experiment part, good quality tungsten metalic tips for experiment were fabricated using our newly developed tip making setup. Then a series of measurements using a technique called electrostatic-manipulation scanning tunneling microscopy (EM-STM) of our own development were performed on a highly oriented pyrolytic graphite (HOPG) surface. The electrostatic interaction between the STM tip and the sample can be tuned to produce both reversible and irreversible large-scale movement of the graphite surface. Under this influence, atomic-resolution STM images reveal that a continuous electronic transition between two distinct patterns can be systematically controlled. DFT calculations reveal that this transition can be related to vertical displacements of the top layer of graphite relative to the bulk. Evidence for horizontal shifts in the top layer of graphite is also presented. Excellent agreement is found between experimental STM images and those simulated using DFT. In addition, the EM-STM technique was also used to controllably and reversibly pull freestanding graphene membranes up to 35 nm from their equilibrium height. Atomic-scale corrugation amplitudes 20 times larger than the STM electronic corrugation for graphene on a substrate were observed. The freestanding graphene membrane responds to a local attractive force created at the STM tip as a highly conductive yet flexible grounding plane with an elastic restoring force.

  5. Anisotropic superconductivity in β-(BDA-TTP)2SbF6: STM spectroscopy

    Science.gov (United States)

    Nomura, K.; Muraoka, R.; Matsunaga, N.; Ichimura, K.; Yamada, J.

    2009-03-01

    We have investigated the gap symmetry in the superconducting phase of β-(BDA-TTP)2SbF6 with use of the scanning tunneling microscope (STM). The tunneling spectra obtained on the conducting surface show a clear superconducting gap structure. Its functional form is of V-shaped similarly to κ-(BEDT-TTF)2X and suggests the anisotropic superconducting gap with line nodes. For lateral surfaces the shape of tunneling spectra varies from the U-shape with relatively large gap to the V-shape with small gap depending on the tunneling direction alternately twice between directional angle 0 and π. From the analysis of conductance curve taking the k dependence of the tunneling probability into account, it is found that the gap has maximum near the a* and c* axes and the nodes appear along near a*+c* and the a-c* directions. These indicate that the d like superconducting pair is formed in this system as the case of κ-(BEDT-TTF)2X. This node direction is consistent with the theoretical prediction based on the spin fluctuation mechanism. However, the zero-bias conductance peak has not been observed yet.

  6. Anisotropic superconductivity in β-(BDA-TTP)2SbF6: STM spectroscopy

    International Nuclear Information System (INIS)

    Nomura, K.; Muraoka, R.; Matsunaga, N.; Ichimura, K.; Yamada, J.

    2009-01-01

    We have investigated the gap symmetry in the superconducting phase of β-(BDA-TTP) 2 SbF 6 with use of the scanning tunneling microscope (STM). The tunneling spectra obtained on the conducting surface show a clear superconducting gap structure. Its functional form is of V-shaped similarly to κ-(BEDT-TTF) 2 X and suggests the anisotropic superconducting gap with line nodes. For lateral surfaces the shape of tunneling spectra varies from the U-shape with relatively large gap to the V-shape with small gap depending on the tunneling direction alternately twice between directional angle 0 and π. From the analysis of conductance curve taking the k dependence of the tunneling probability into account, it is found that the gap has maximum near the a* and c* axes and the nodes appear along near a*+c* and the a-c* directions. These indicate that the d x 2 -y 2 like superconducting pair is formed in this system as the case of κ-(BEDT-TTF) 2 X. This node direction is consistent with the theoretical prediction based on the spin fluctuation mechanism. However, the zero-bias conductance peak has not been observed yet

  7. Epidemiology, imaging, and treatment of Lisfranc fracture-dislocations revisited

    International Nuclear Information System (INIS)

    Kalia, Vivek; Fishman, Elliot K.; Carrino, John A.; Fayad, Laura M.

    2012-01-01

    The purpose of this article is to discuss the features of Lisfranc injuries and identify their typical imaging findings on radiographs, CT, and MR imaging. Lisfranc injuries are most often caused by hyperplantarflexion of the foot, often during a sporting injury or in high-speed motor vehicle collisions. The most common radiographic findings include diastasis of the base of the first and second metatarsals and the ''fleck'' sign, though neither is necessarily present in every Lisfranc fracture-dislocation. Owing to their often subtle radiographic presentation, clinically suspected Lisfranc injuries warrant imaging with a more sensitive test for the detection of osseous and ligamentous Lisfranc injuries. 3D CT imaging provides a comprehensive evaluation of the injury for optimal treatment planning, with resultant decreased long-term patient morbidity. Furthermore, 3D volume-rendered CT and CT multiplanar reconstructions (MPRs) provide osseous and neurovascular anatomic detail that may be a considerable help with surgical planning for operative cases of Lisfranc injuries. Also, with 3D CT and MPRs, other occult fractures, which are common in patients with high-energy injury and multiple trauma, may become evident. (orig.)

  8. The Spleen Revisited: An Overview on Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    João Palas

    2013-01-01

    Full Text Available Despite being well visualized by different cross-sectional imaging techniques, the spleen is many times overlooked during the abdominal examination. The major reason is the low frequency of splenic abnormalities, the majority consisting of incidental findings. There has been a steady increase in the number of performed abdominal magnetic resonance imaging (MRI studies; therefore, it is important to be familiar to the major MRI characteristics of disease processes involving the spleen, in order to interpret the findings correctly, reaching whenever possible the appropriate diagnosis. The spleen may be involved in several pathologic conditions like congenital diseases, trauma, inflammation, vascular disorders and hematologic disorders, benign and malignant tumors, and other disease processes that focally or diffusely affect the spleen. This paper presents a description and representative MRI images for many of these disorders.

  9. STM-Induced Void Formation at the Al{sub 2}O{sub 3}/Ni{sub 3}Al(111) Interface

    Energy Technology Data Exchange (ETDEWEB)

    Magtoto, N.P.; Niu, C.; Anzaldura, M.; Kelber, J.A.; Jennison, D.R.

    2000-09-21

    Under UHV conditions at 300 K, the applied electric field and/or resulting current from an STM tip creates nanoscale voids at the interface between an epitaxial, 7.0 {angstrom} thick Al{sub 2}O{sub 3} film and a Ni{sub 3}Al(111) substrate. This phenomenon is independent of tip polarity. Constant current (1 nA) images obtained at +0.1 V bias and +2.0 bias voltage (sample positive) reveal that voids are within the metal at the interface and, when small, are capped by the oxide film. Void size increases with time of exposure. The rate of void growth increases with applied bias/field and tunneling current, and increases significantly for field strengths >5 MV/cm, well below the dielectric breakdown threshold of 12 {+-} 1 MV/cm. Slower rates of void growth are, however, observed at lower applied field strengths. Continued growth of voids, to {approximately}30 {angstrom} deep and {approximately}500 {angstrom} wide, leads to the eventual failure of the oxide overlayer. Density Functional Theory calculations suggest a reduction-oxidation (REDOX) mechanism: interracial metal atoms are oxidized via transport into the oxide, while oxide surface Al cations are reduced to admetal species which rapidly diffuse away. This is found to be exothermic in model calculations, regardless of the details of the oxide film structure; thus, the barriers to void formation are kinetic rather than thermodynamic. We discuss our results in terms of mechanisms for the localized pitting corrosion of aluminum, as our results suggest nanovoid formation requires just electric field and current, which are ubiquitous in environmental conditions.

  10. The hard-core model on random graphs revisited

    International Nuclear Information System (INIS)

    Barbier, Jean; Krzakala, Florent; Zhang, Pan; Zdeborová, Lenka

    2013-01-01

    We revisit the classical hard-core model, also known as independent set and dual to vertex cover problem, where one puts particles with a first-neighbor hard-core repulsion on the vertices of a random graph. Although the case of random graphs with small and very large average degrees respectively are quite well understood, they yield qualitatively different results and our aim here is to reconciliate these two cases. We revisit results that can be obtained using the (heuristic) cavity method and show that it provides a closed-form conjecture for the exact density of the densest packing on random regular graphs with degree K ≥ 20, and that for K > 16 the nature of the phase transition is the same as for large K. This also shows that the hard-code model is the simplest mean-field lattice model for structural glasses and jamming

  11. The Effects of Korean Medical Service Quality and Satisfaction on Revisit Intention of the United Arab Emirates Government Sponsored Patients.

    Science.gov (United States)

    Lee, Seoyoung; Kim, Eun-Kyung

    2017-06-01

    The purpose of this study was to investigate medical service quality, satisfaction and to examine factors influencing hospital revisit intention of the United Arab Emirates government sponsored patients in Korea. A total of 152 UAE government sponsored patients who visited Korean hospitals participated in the questionnaire survey from August to November 2016. Stepwise multiple regression was used to identify the factors that affected the revisit intention of the participants. The mean scores of medical service quality, satisfaction, and revisit intention were 5.72 out of 7, 88.88 out of 100, 4.59 out of 5, respectively. Medical service quality and satisfaction, Medical service quality and revisit intention, satisfaction and revisit intention were positively correlated. Medical service of physician, visiting routes and responsiveness of medical service quality explained about 23.8% of revisit intention. There are needs for physicians to communicate with patients while ensuring sufficient consultation time based on excellent medical skills and nurses to respond immediately for the patients' needs through an empathic encounter in order to improve medical service quality and patient satisfaction so that to increase the revisit intention of the United Arab Emirates government sponsored patients. Further, it is necessary for the hospitals to have support plans for providing country specialized services in consideration of the UAE culture to ensure that physicians' and nurses' competencies are not undervalued by non-medical service elements such as interpreters and meals. Copyright © 2017. Published by Elsevier B.V.

  12. Analysis of an ordered, comprehensive STM mutant library in infectious Borrelia burgdorferi: insights into the genes required for mouse infectivity.

    Directory of Open Access Journals (Sweden)

    Tao Lin

    Full Text Available The identification of genes important in the pathogenesis of Lyme disease Borrelia has been hampered by exceedingly low transformation rates in low-passage, infectious organisms. Using the infectious, moderately transformable B. burgdorferi derivative 5A18NP1 and signature-tagged versions of the Himar1 transposon vector pGKT, we have constructed a defined transposon library for the efficient genome-wide investigation of genes required for wild-type pathogenesis, in vitro growth, physiology, morphology, and plasmid replication. To facilitate analysis, the insertion sites of 4,479 transposon mutants were determined by sequencing. The transposon insertions were widely distributed across the entire B. burgdorferi genome, with an average of 2.68 unique insertion sites per kb DNA. The 10 linear plasmids and 9 circular plasmids had insertions in 33 to 100 percent of their predicted genes. In contrast, only 35% of genes in the 910 kb linear chromosome had incapacitating insertions; therefore, the remaining 601 chromosomal genes may represent essential gene candidates. In initial signature-tagged mutagenesis (STM analyses, 434 mutants were examined at multiple tissue sites for infectivity in mice using a semi-quantitative, Luminex-based DNA detection method. Examples of genes found to be important in mouse infectivity included those involved in motility, chemotaxis, the phosphoenolpyruvate phosphotransferase system, and other transporters, as well as putative plasmid maintenance genes. Availability of this ordered STM library and a high-throughput screening method is expected to lead to efficient assessment of the roles of B. burgdorferi genes in the infectious cycle and pathogenesis of Lyme disease.

  13. Image charges revisited: a closed form solution

    International Nuclear Information System (INIS)

    Choy, T. C.

    2000-01-01

    We demonstrate that the corrections to the classical Kelvin image theory due to finite electron screening length )λ, recently discussed by Roulet and Saint Jean, Am. J. Phys. 68(4) 319, is amenable to an exact closed form solution in terms of an integral involving Bessel functions. An error arising from an incorrect choice of boundary conditions is rectified as well, enabling also a complete solution for all potentials - both inside and outside the metal surface

  14. Coexistence of multiple conformations in cysteamine monolayers on Au(111)

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Bilic, A; Reimers, JR

    2005-01-01

    The structural organization, catalytic function, and electronic properties of cysteamine monolayers on Au(111) have been addressed comprehensively by voltammetry, in situ scanning tunneling microscopy (STM) in anaerobic environment, and a priori molecular dynamics (MD) simulation and STM image si...

  15. Coccolithophorids in polar waters: Wigwamma spp. revisited

    DEFF Research Database (Denmark)

    Thomsen, Helge Abildhauge; Østergaard, Jette B.; Heldal, Mikal

    2013-01-01

    A contingent of weakly calcified coccolithophorid genera and species were described from polar regions almost 40 years ago. In the interim period a few additional findings have been reported enlarging the realm of some of the species. The genus Wigwamma is revisited here with the purpose of provi...... appearance of the coccolith armour of the cell...

  16. Surface structure and electronic states of epitaxial β-FeSi.sub.2./sub.(100)/Si(001) thin films: Combined quantitative LEED, ab initio DFT, and STM study

    Czech Academy of Sciences Publication Activity Database

    Romanyuk, Olexandr; Hattori, K.; Someta, M.; Daimon, H.

    2014-01-01

    Roč. 90, č. 15 (2014), "155305-1"-"155305-9" ISSN 1098-0121 Grant - others:AVČR(CZ) M100101201; Murata Science Foundation(JP) Project n. 00295 Institutional support: RVO:68378271 Keywords : iron silicide * LEED I-V * DFT * STM * surface reconstruction * surface states Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  17. The significance test controversy revisited the fiducial Bayesian alternative

    CERN Document Server

    Lecoutre, Bruno

    2014-01-01

    The purpose of this book is not only to revisit the “significance test controversy,”but also to provide a conceptually sounder alternative. As such, it presents a Bayesian framework for a new approach to analyzing and interpreting experimental data. It also prepares students and researchers for reporting on experimental results. Normative aspects: The main views of statistical tests are revisited and the philosophies of Fisher, Neyman-Pearson and Jeffrey are discussed in detail. Descriptive aspects: The misuses of Null Hypothesis Significance Tests are reconsidered in light of Jeffreys’ Bayesian conceptions concerning the role of statistical inference in experimental investigations. Prescriptive aspects: The current effect size and confidence interval reporting practices are presented and seriously questioned. Methodological aspects are carefully discussed and fiducial Bayesian methods are proposed as a more suitable alternative for reporting on experimental results. In closing, basic routine procedures...

  18. Compact design of a transmission electron microscope-scanning tunneling microscope holder with three-dimensional coarse motion

    International Nuclear Information System (INIS)

    Svensson, K.; Jompol, Y.; Olin, H.; Olsson, E.

    2003-01-01

    A scanning tunneling microscope (STM) with a compact, three-dimensional, inertial slider design is presented. Inertial sliding of the STM tip, in three dimensions, enables coarse motion and scanning using only one piezoelectric tube. Using the same electronics both for scanning and inertial sliding, step lengths of less than 5% of the piezo range were achieved. The compact design, less than 1 cm3 in volume, ensures a low mechanical noise level and enables us to fit the STM into the sample holder of a transmission electron microscope (TEM), while maintaining atomic scale resolution in both STM and TEM imaging

  19. Anchoring of organic molecules to a metal surface: HtBDC on Cu(110)

    DEFF Research Database (Denmark)

    Schunack, M.; Petersen, L.; Kuhnle, A.

    2001-01-01

    The interaction of largish molecules with metal surfaces has been studied by combining the imaging and manipulation capabilities of the scanning tunneling microscope (STM). At the atomic scale, the STM results directly reveal that the adsorption of a largish organic molecule can induce...

  20. Satellite failures revisited

    Science.gov (United States)

    Balcerak, Ernie

    2012-12-01

    In January 1994, the two geostationary satellites known as Anik-E1 and Anik-E2, operated by Telesat Canada, failed one after the other within 9 hours, leaving many northern Canadian communities without television and data services. The outage, which shut down much of the country's broadcast television for hours and cost Telesat Canada more than $15 million, generated significant media attention. Lam et al. used publicly available records to revisit the event; they looked at failure details, media coverage, recovery effort, and cost. They also used satellite and ground data to determine the precise causes of those satellite failures. The researchers traced the entire space weather event from conditions on the Sun through the interplanetary medium to the particle environment in geostationary orbit.

  1. The use of Scanning Tunneling Microscope as a novel characterization tool for metallic alloys

    International Nuclear Information System (INIS)

    Brezenitsky, M.; Moreh, R.; Dayan, D.; Kimmel, G.

    1996-01-01

    A novel method is reported for characterizing the microstructure of metals and alloys by utilizing the surface imaging properties of a STM (Scanning Tunneling microscope). In the present work there is no need to take advantage of the high atomic resolution of the STM, instead only gross resolution is required. Twenty different samples having different grain sizes (caused by the mosaic structure) and ranging between 20 to 200 nm were prepared. These dimensions are far below the resolution limit of optical microscopes. The samples were first studied using line profile analysis of XRD spectra while focusing on two of the most characteristic properties of steel which are: grain size and the deviation from cubic symmetry. Some of the samples showed nonuniform XRD line broadening effects, which could be attributed to a tetragonal distortion. If it is true, the samples must consist of martensitic twinned structure, as a result of the typical y to a shear transformation in steels. The samples were then studied using the STM. In general, many 1000 nm x 1000 )zm STM scans were carried out on each sample. In all cases of irregular XRD line broadening, the STM identified bands and sub-bands in the images which fitted the usual twining structure in steels. In addition, the STM images were found to show individual domains, from which histograms of the grain dimensions for each sample were prepared and compared to the XRD data. An excellent agreement was observed between tile two sets of data of grain sizes. The present method is much simpler than that which employs the Transmission Electron Microscope (TEM) as it can be carried out in air and no special requirements on sample preparation is necessary. This work establishes the STM as a very useful characterization tool for studies in metallurgy and metal physics. (author)

  2. Pockets of Participation: Revisiting Child-Centred Participation Research

    Science.gov (United States)

    Franks, Myfanwy

    2011-01-01

    This article revisits the theme of the clash of interests and power relations at work in participatory research which is prescribed from above. It offers a possible route toward solving conflict between adult-led research carried out by young researchers, funding requirements and organisational constraints. The article explores issues of…

  3. Faraday effect revisited: sum rules and convergence issues

    DEFF Research Database (Denmark)

    Cornean, Horia; Nenciu, Gheorghe

    2010-01-01

    This is the third paper of a series revisiting the Faraday effect. The question of the absolute convergence of the sums over the band indices entering the Verdet constant is considered. In general, sum rules and traces per unit volume play an important role in solid-state physics, and they give...

  4. Surface science approach to Pt/carbon model catalysts: XPS, STM and microreactor studies

    Science.gov (United States)

    Motin, Abdul Md.; Haunold, Thomas; Bukhtiyarov, Andrey V.; Bera, Abhijit; Rameshan, Christoph; Rupprechter, Günther

    2018-05-01

    Pt nanoparticles supported on carbon are an important technological catalyst. A corresponding model catalyst was prepared by physical vapor deposition (PVD) of Pt on sputtered HOPG (highly oriented pyrolytic graphite). The carbon substrate before and after sputtering as well as the Pt/HOPG system before and after Pt deposition and annealing were examined by XPS and STM. This yielded information on the surface density of defects, which serve as nucleation centres for Pt, and on the size distribution (mean size/height) of the Pt nanoparticles. Two different model catalysts were prepared with mean sizes of 2.0 and 3.6 nm, both turned out to be stable upon UHV-annealing to 300 °C. After transfer into a UHV-compatible flow microreactor and subsequent cleaning in UHV and under mbar pressure, the catalytic activity of the Pt/HOPG model system for ethylene hydrogenation was examined under atmospheric pressure flow conditions. This enabled to determine temperature-dependent conversion rates, turnover frequencies (TOFs) and activation energies. The catalytic results obtained are in line with the characteristics of technological Pt/C, demonstrating the validity of the current surface science based model catalyst approach.

  5. Gold Mining by Alkanethiol Radicals: Vacancies and Pits in the Self-Assembled Monolayers of 1-Propanethiol and 1-Butanethiol on Au(111)

    DEFF Research Database (Denmark)

    Wang, Yun; Chi, Qijin; Hush, Noel S.

    2011-01-01

    Scanning-tunneling microscopy (STM) under electrochemical control (in situ STM) in aqueous solution, combined with a priori density functional theory (DFT) image simulations at room temperature, reveals the atomic nature of the interface between Au(111) and self-assembled monolayers (SAMs) of 1-p...

  6. Epitaxial deposition of silver ultrafine nano-clusters on defect-free surfaces of HOPG-derived few-layer graphene in a UHV multi-chamber by in-situ STM, ex-situ XPS and ab initio calculations

    CSIR Research Space (South Africa)

    Ndlovu, GF

    2012-03-01

    Full Text Available The growth of three-dimensional ultra-fine spherical nano-particles of silver on few layers of graphene derived from highly oriented pyrolytic graphite in ultra-high vacuum were characterized using in situ scanning tunneling microscopy (STM...

  7. Short or Long End of the Lever? Associations between Provider Communication of the "Asthma-Action Plan" and Outpatient Revisits for Pediatric Asthma.

    Science.gov (United States)

    Rangachari, Pavani; Mehta, Renuka; Rethemeyer, R Karl; Ferrang, Carole; Dennis, Clifton; Redd, Vickie

    2015-10-01

    At the Children's Hospital of Georgia (CHOG), we found that outpatient revisits for pediatric asthma were significantly above national norms. According to the NIH, costly hospital revisits for asthma can be prevented through guidelines-based self-management of asthma, central to which, is the use of a written Asthma-Action Plan (AAP). The asthma services literature has emphasized the role of the healthcare provider in promoting asthma self-management using the AAP, to prevent hospital revisits. On the other hand, the asthma policy literature has emphasized the need for community-based interventions to promote asthma self-management. A gap remains in understanding the extent of leverage that healthcare providers may have in preventing hospital revisits for asthma, through effective communication of AAP in the outpatient setting. Our study sought to address this gap. We conducted a 6-month intervention to implement "patient-and-family-centered communication of the AAP" in CHOG outpatient clinics, based on the "change-management" theoretical framework. Provider communication of AAP was assessed through a survey of "Parent Understanding of the Child's AAP." A quasi-experimental approach was used to measure outpatient revisits for pediatric asthma, pre- and post-intervention. Survey results showed that provider communication of the AAP was unanimously perceived highly positively by parents of pediatric asthma patients, across various metrics of patient-centered care. However, there were no statistically significant differences in outpatient "revisit behavior" for pediatric asthma between pre- and post-intervention periods after controlling for several demographic variables. Additionally, revisits remained significantly above national norms. Results suggest limited potential of "effective provider communication of AAP," in reducing outpatient revisits for pediatric asthma; and indicate need for broader community-based interventions to address patient life variables

  8. EDITORIAL: Three decades of scanning tunnelling microscopy that changed the course of surface science Three decades of scanning tunnelling microscopy that changed the course of surface science

    Science.gov (United States)

    Ramachandra Rao, M. S.; Margaritondo, Giorgio

    2011-11-01

    Three decades ago, with a tiny tip of platinum, the scientific world saw the real space imaging of single atoms with unprecedented spatial resolution. This signalled the birth of one of the most versatile surface probes, based on the physics of quantum mechanical tunnelling: the scanning tunnelling microscope (STM). Invented in 1981 by Gerd Binnig and Heinrich Rohrer of IBM, Zurich, it led to their award of the 1986 Nobel Prize. Atoms, once speculated to be abstract entities used by theoreticians for mere calculations, can be seen to exist for real with the nano-eye of an STM tip that also gives real-space images of molecules and adsorbed complexes on surfaces. From a very fundamental perspective, the STM changed the course of surface science and engineering. STM also emerged as a powerful tool to study various fundamental phenomena relevant to the properties of surfaces in technological applications such as tribology, medical implants, catalysis, sensors and biology—besides elucidating the importance of local bonding geometries and defects, non-periodic structures and the co-existence of nano-scale phases. Atom-level probing, once considered a dream, has seen the light with the evolution of STM. An important off-shoot of STM was the atomic force microscope (AFM) for surface mapping of insulating samples. Then followed the development of a flurry of techniques under the general name of scanning probe microscopy (SPM). These techniques (STM, AFM, MFM, PFM etc) designed for atomic-scale-resolution imaging and spectroscopy, have led to brand new developments in surface analysis. All of these novel methods enabled researchers in recent years to image and analyse complex surfaces on microscopic and nanoscopic scales. All of them utilize a small probe for sensing the surface. The invention of AFM by Gerd Binnig, Calvin Quate and Christopher Gerber opened up new opportunities for characterization of a variety of materials, and various industrial applications could be

  9. A semi-automatic procedure for texturing of laser scanning point clouds with google streetview images

    NARCIS (Netherlands)

    Lichtenauer, J.F.; Sirmacek, B.

    2015-01-01

    We introduce a method to texture 3D urban models with photographs that even works for Google Streetview images and can be done with currently available free software. This allows realistic texturing, even when it is not possible or cost-effective to (re)visit a scanned site to take textured scans or

  10. Additively homomorphic encryption with a double decryption mechanism, revisited

    NARCIS (Netherlands)

    Peter, Andreas; Kronberg, M.; Trei, W.; Katzenbeisser, S.

    We revisit the notion of additively homomorphic encryption with a double decryption mechanism (DD-PKE), which allows for additions in the encrypted domain while having a master decryption procedure that can decrypt all properly formed ciphertexts by using a special master secret. This type of

  11. Moral Judgment Development across Cultures: Revisiting Kohlberg's Universality Claims

    Science.gov (United States)

    Gibbs, John C.; Basinger, Karen S.; Grime, Rebecca L.; Snarey, John R.

    2007-01-01

    This article revisits Kohlberg's cognitive developmental claims that stages of moral judgment, facilitative processes of social perspective-taking, and moral values are commonly identifiable across cultures. Snarey [Snarey, J. (1985). "The cross-cultural universality of social-moral development: A critical review of Kohlbergian research."…

  12. Radiative corrections to double-Dalitz decays revisited

    Science.gov (United States)

    Kampf, Karol; Novotný, Jiři; Sanchez-Puertas, Pablo

    2018-03-01

    In this study, we revisit and complete the full next-to-leading order corrections to pseudoscalar double-Dalitz decays within the soft-photon approximation. Comparing to the previous study, we find small differences, which are nevertheless relevant for extracting information about the pseudoscalar transition form factors. Concerning the latter, these processes could offer the opportunity to test them—for the first time—in their double-virtual regime.

  13. A Feminist Revisit to the First-Year Curriculum.

    Science.gov (United States)

    Bernstein, Anita

    1996-01-01

    A seminar at Chicago-Kent College of Law (Illinois) that reviews six first-year law school courses by focusing on feminist issues in course content and structure is described. The seminar functions as both a review and a shift in perspective. Courses revisited include civil procedure, contracts, criminal law, justice and the legal system,…

  14. Short-term memory for spatial, sequential and duration information.

    Science.gov (United States)

    Manohar, Sanjay G; Pertzov, Yoni; Husain, Masud

    2017-10-01

    Space and time appear to play key roles in the way that information is organized in short-term memory (STM). Some argue that they are crucial contexts within which other stored features are embedded, allowing binding of information that belongs together within STM. Here we review recent behavioral, neurophysiological and imaging studies that have sought to investigate the nature of spatial, sequential and duration representations in STM, and how these might break down in disease. Findings from these studies point to an important role of the hippocampus and other medial temporal lobe structures in aspects of STM, challenging conventional accounts of involvement of these regions in only long-term memory.

  15. Quantum duel revisited

    International Nuclear Information System (INIS)

    Schmidt, Alexandre G M; Paiva, Milena M

    2012-01-01

    We revisit the quantum two-person duel. In this problem, both Alice and Bob each possess a spin-1/2 particle which models dead and alive states for each player. We review the Abbott and Flitney result—now considering non-zero α 1 and α 2 in order to decide if it is better for Alice to shoot or not the second time—and we also consider a duel where players do not necessarily start alive. This simple assumption allows us to explore several interesting special cases, namely how a dead player can win the duel shooting just once, or how can Bob revive Alice after one shot, and the better strategy for Alice—being either alive or in a superposition of alive and dead states—fighting a dead opponent. (paper)

  16. The Importance of Being a Complement: CED Effects Revisited

    Science.gov (United States)

    Jurka, Johannes

    2010-01-01

    This dissertation revisits subject island effects (Ross 1967, Chomsky 1973) cross-linguistically. Controlled acceptability judgment studies in German, English, Japanese and Serbian show that extraction out of specifiers is consistently degraded compared to extraction out of complements, indicating that the Condition on Extraction domains (CED,…

  17. The Effect of Brand Equity and Perceived Value on Customer Revisit Intention: A Study in Quick-Service Restaurants in Vietnam

    Directory of Open Access Journals (Sweden)

    Ly Thi Minh Pham

    2016-10-01

    Full Text Available The purpose of this study is to examine how brand equity, from a customer point of view, influences quick-service restaurant revisit intention. The authors propose a conceptual framework in which three dimensions of brand equity including brand associations combined with brand awareness, perceived quality, brand loyalty and perceived value are related to revisit intention. Data from 570 customers who had visited four quick-service restaurants in Ho Chi Minh City were used for the structural equation modelling (SEM analysis. The results show that strong brand equity is significantly correlated with revisit intention. Additionally, the effect of brand equity on revisit intention was mediated by perceived value, among others. Overall, this study emphasizes the importance of perceived value in lodging in the customer’s mind. Finally, managerial implications are presented based on the study results.

  18. Literary Origins of the Term "School Psychologist" Revisited

    Science.gov (United States)

    Fagan, Thomas K.

    2005-01-01

    Previous research on the literary origins of the term "school psychologist" is revisited, and conclusions are revised in light of new evidence. It appears that the origin of the term in the American literature occurred as early as 1898 in an article by Hugo Munsterberg, predating the usage by Wilhelm Stern in 1911. The early references to the…

  19. A Multi-Level Model of Moral Functioning Revisited

    Science.gov (United States)

    Reed, Don Collins

    2009-01-01

    The model of moral functioning scaffolded in the 2008 "JME" Special Issue is here revisited in response to three papers criticising that volume. As guest editor of that Special Issue I have formulated the main body of this response, concerning the dynamic systems approach to moral development, the problem of moral relativism and the role of…

  20. Cameras and settings for optimal image capture from UAVs

    Science.gov (United States)

    Smith, Mike; O'Connor, James; James, Mike R.

    2017-04-01

    Aerial image capture has become very common within the geosciences due to the increasing affordability of low payload (markets. Their application to surveying has led to many studies being undertaken using UAV imagery captured from consumer grade cameras as primary data sources. However, image quality and the principles of image capture are seldom given rigorous discussion which can lead to experiments being difficult to accurately reproduce. In this contribution we revisit the underpinning concepts behind image capture, from which the requirements for acquiring sharp, well exposed and suitable imagery are derived. This then leads to discussion of how to optimise the platform, camera, lens and imaging settings relevant to image quality planning, presenting some worked examples as a guide. Finally, we challenge the community to make their image data open for review in order to ensure confidence in the outputs/error estimates, allow reproducibility of the results and have these comparable with future studies. We recommend providing open access imagery where possible, a range of example images, and detailed metadata to rigorously describe the image capture process.

  1. Short or Long End of the Lever? Associations between Provider Communication of the “Asthma-Action Plan” and Outpatient Revisits for Pediatric Asthma

    Science.gov (United States)

    Rangachari, Pavani; Mehta, Renuka; Rethemeyer, R. Karl; Ferrang, Carole; Dennis, Clifton; Redd, Vickie

    2017-01-01

    Background At the Children’s Hospital of Georgia (CHOG), we found that outpatient revisits for pediatric asthma were significantly above national norms. According to the NIH, costly hospital revisits for asthma can be prevented through guidelines-based self-management of asthma, central to which, is the use of a written Asthma-Action Plan (AAP). Purpose The asthma services literature has emphasized the role of the healthcare provider in promoting asthma self-management using the AAP, to prevent hospital revisits. On the other hand, the asthma policy literature has emphasized the need for community-based interventions to promote asthma self-management. A gap remains in understanding the extent of leverage that healthcare providers may have in preventing hospital revisits for asthma, through effective communication of AAP in the outpatient setting. Our study sought to address this gap. Methods We conducted a 6-month intervention to implement “patient-and-family-centered communication of the AAP” in CHOG outpatient clinics, based on the “change-management” theoretical framework. Provider communication of AAP was assessed through a survey of “Parent Understanding of the Child’s AAP.” A quasi-experimental approach was used to measure outpatient revisits for pediatric asthma, pre- and post-intervention. Results Survey results showed that provider communication of the AAP was unanimously perceived highly positively by parents of pediatric asthma patients, across various metrics of patient-centered care. However, there were no statistically significant differences in outpatient “revisit behavior” for pediatric asthma between pre- and post-intervention periods after controlling for several demographic variables. Additionally, revisits remained significantly above national norms. Conclusions Results suggest limited potential of “effective provider communication of AAP,” in reducing outpatient revisits for pediatric asthma; and indicate need for

  2. High-stability cryogenic scanning tunneling microscope based on a closed-cycle cryostat

    Energy Technology Data Exchange (ETDEWEB)

    Hackley, Jason D.; Kislitsyn, Dmitry A.; Beaman, Daniel K.; Nazin, George V., E-mail: gnazin@uoregon.edu [Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene, Oregon 97403 (United States); Ulrich, Stefan [RHK Technology, Inc., 1050 East Maple Road, Troy, Michigan 48083 (United States)

    2014-10-15

    We report on the design and operation of a cryogenic ultra-high vacuum (UHV) scanning tunneling microscope (STM) coupled to a closed-cycle cryostat (CCC). The STM is thermally linked to the CCC through helium exchange gas confined inside a volume enclosed by highly flexible rubber bellows. The STM is thus mechanically decoupled from the CCC, which results in a significant reduction of the mechanical noise transferred from the CCC to the STM. Noise analysis of the tunneling current shows current fluctuations up to 4% of the total current, which translates into tip-sample distance variations of up to 1.5 picometers. This noise level is sufficiently low for atomic-resolution imaging of a wide variety of surfaces. To demonstrate this, atomic-resolution images of Au(111) and NaCl(100)/Au(111) surfaces, as well as of carbon nanotubes deposited on Au(111), were obtained. Thermal drift analysis showed that under optimized conditions, the lateral stability of the STM scanner can be as low as 0.18 Å/h. Scanning Tunneling Spectroscopy measurements based on the lock-in technique were also carried out, and showed no detectable presence of noise from the closed-cycle cryostat. Using this cooling approach, temperatures as low as 16 K at the STM scanner have been achieved, with the complete cool-down of the system typically taking up to 12 h. These results demonstrate that the constructed CCC-coupled STM is a highly stable instrument capable of highly detailed spectroscopic investigations of materials and surfaces at the atomic scale.

  3. High-stability cryogenic scanning tunneling microscope based on a closed-cycle cryostat.

    Science.gov (United States)

    Hackley, Jason D; Kislitsyn, Dmitry A; Beaman, Daniel K; Ulrich, Stefan; Nazin, George V

    2014-10-01

    We report on the design and operation of a cryogenic ultra-high vacuum (UHV) scanning tunneling microscope (STM) coupled to a closed-cycle cryostat (CCC). The STM is thermally linked to the CCC through helium exchange gas confined inside a volume enclosed by highly flexible rubber bellows. The STM is thus mechanically decoupled from the CCC, which results in a significant reduction of the mechanical noise transferred from the CCC to the STM. Noise analysis of the tunneling current shows current fluctuations up to 4% of the total current, which translates into tip-sample distance variations of up to 1.5 picometers. This noise level is sufficiently low for atomic-resolution imaging of a wide variety of surfaces. To demonstrate this, atomic-resolution images of Au(111) and NaCl(100)/Au(111) surfaces, as well as of carbon nanotubes deposited on Au(111), were obtained. Thermal drift analysis showed that under optimized conditions, the lateral stability of the STM scanner can be as low as 0.18 Å/h. Scanning Tunneling Spectroscopy measurements based on the lock-in technique were also carried out, and showed no detectable presence of noise from the closed-cycle cryostat. Using this cooling approach, temperatures as low as 16 K at the STM scanner have been achieved, with the complete cool-down of the system typically taking up to 12 h. These results demonstrate that the constructed CCC-coupled STM is a highly stable instrument capable of highly detailed spectroscopic investigations of materials and surfaces at the atomic scale.

  4. Reframing in dentistry: Revisited

    Directory of Open Access Journals (Sweden)

    Sivakumar Nuvvula

    2013-01-01

    Full Text Available The successful practice of dentistry involves a good combination of technical skills and soft skills. Soft skills or communication skills are not taught extensively in dental schools and it can be challenging to learn and at times in treating dental patients. Guiding the child′s behavior in the dental operatory is one of the preliminary steps to be taken by the pediatric dentist and one who can successfully modify the behavior can definitely pave the way for a life time comprehensive oral care. This article is an attempt to revisit a simple behavior guidance technique, reframing and explain the possible psychological perspectives behind it for better use in the clinical practice.

  5. The drive revisited: Mastery and satisfaction.

    Science.gov (United States)

    Denis, Paul

    2016-06-01

    Starting from the theory of the libido and the notions of the experience of satisfaction and the drive for mastery introduced by Freud, the author revisits the notion of the drive by proposing the following model: the drive takes shape in the combination of two currents of libidinal cathexis, one which takes the paths of the 'apparatus for obtaining mastery' (the sense-organs, motricity, etc.) and strives to appropriate the object, and the other which cathects the erotogenic zones and the experience of satisfaction that is experienced through stimulation in contact with the object. The result of this combination of cathexes constitutes a 'representation', the subsequent evocation of which makes it possible to tolerate for a certain period of time the absence of a satisfying object. On the basis of this conception, the author distinguishes the representations proper, vehicles of satisfaction, from imagos and traumatic images which give rise to excitation that does not link up with the paths taken by the drives. This model makes it possible to conciliate the points of view of the advocates of 'object-seeking' and of those who give precedence to the search for pleasure, and, further, to renew our understanding of object-relations, which can then be approached from the angle of their relations to infantile sexuality. Destructiveness is considered in terms of "mastery madness" and not in terms of the late Freudian hypothesis of the death drive. Copyright © 2015 Institute of Psychoanalysis.

  6. Nanoscale phosphorus atom arrays created using STM for the fabrication of a silicon based quantum computer.

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, J. L. (Jeremy L.); Schofield, S. R. (Steven R.); Simmons, M. Y. (Michelle Y.); Clark, R. G. (Robert G.); Dzurak, A. S. (Andrew S.); Curson, N. J. (Neil J.); Kane, B. E. (Bruce E.); McAlpine, N. S. (Neal S.); Hawley, M. E. (Marilyn E.); Brown, G. W. (Geoffrey W.)

    2001-01-01

    Quantum computers offer the promise of formidable computational power for certain tasks. Of the various possible physical implementations of such a device, silicon based architectures are attractive for their scalability and ease of integration with existing silicon technology. These designs use either the electron or nuclear spin state of single donor atoms to store quantum information. Here we describe a strategy to fabricate an array of single phosphorus atoms in silicon for the construction of such a silicon based quantum computer. We demonstrate the controlled placement of single phosphorus bearing molecules on a silicon surface. This has been achieved by patterning a hydrogen mono-layer 'resist' with a scanning tunneling microscope (STM) tip and exposing the patterned surface to phosphine (PH3) molecules. We also describe preliminary studies into a process to incorporate these surface phosphorus atoms into the silicon crystal at the array sites. Keywords: Quantum computing, nanotechriology scanning turincling microscopy, hydrogen lithography

  7. Surface species formed by the adsorption and dissociation of water molecules on Ru(0001) surface containing a small coverage of carbon atoms studied by scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dept of Materials Science and Engineering UCB; Dept of Applied Science and Technology, UCB; Institut de Ciencia de Materials de Barcelona, Barcelona, Spain; Instituto de Ciencia de Materiales de Madrid, Madrid, Spain; Department of Mechanical Engineering, Yale University; Salmeron, Miquel; Shimizu, Tomoko K.; Mugarza, Aitor; Cerda, Jorge I.; Heyde, Markus; Qi, Yabing; Schwarz, Udo D.; Ogletree, D. Frank; Salmeron, Miquel

    2008-04-26

    The adsorption and dissociation of water on a Ru(0001) surface containing a small amount ({le} 3 %) of carbon impurities was studied by scanning tunneling microscopy (STM). Various surface species are formed depending on the temperature. These include molecular H{sub 2}O, H{sub 2}O-C complexes, H, O, OH and CH. Clusters of either pure H{sub 2}O or mixed H{sub 2}O-OH species are also formed. Each of these species produces a characteristic contrast in the STM images and can be identified by experiment and by ab initio total energy calculations coupled with STM image simulations. Manipulation of individual species via excitation of vibrational modes with the tunneling electrons has been used as supporting evidence.

  8. Optimized imaging using non-rigid registration

    International Nuclear Information System (INIS)

    Berkels, Benjamin; Binev, Peter; Blom, Douglas A.; Dahmen, Wolfgang; Sharpley, Robert C.; Vogt, Thomas

    2014-01-01

    The extraordinary improvements of modern imaging devices offer access to data with unprecedented information content. However, widely used image processing methodologies fall far short of exploiting the full breadth of information offered by numerous types of scanning probe, optical, and electron microscopies. In many applications, it is necessary to keep measurement intensities below a desired threshold. We propose a methodology for extracting an increased level of information by processing a series of data sets suffering, in particular, from high degree of spatial uncertainty caused by complex multiscale motion during the acquisition process. An important role is played by a non-rigid pixel-wise registration method that can cope with low signal-to-noise ratios. This is accompanied by formulating objective quality measures which replace human intervention and visual inspection in the processing chain. Scanning transmission electron microscopy of siliceous zeolite material exhibits the above-mentioned obstructions and therefore serves as orientation and a test of our procedures. - Highlights: • Developed a new process for extracting more information from a series of STEM images. • An objective non-rigid registration process copes with distortions. • Images of zeolite Y show retrieval of all information available from the data set. • Quantitative measures of registration quality were implemented. • Applicable to any serially acquired data, e.g. STM, AFM, STXM, etc

  9. Atomic-scale structure of single-layer MoS2 nanoclusters

    DEFF Research Database (Denmark)

    Helveg, S.; Lauritsen, J. V.; Lægsgaard, E.

    2000-01-01

    We have studied using scanning tunneling microscopy (STM) the atomic-scale realm of molybdenum disulfide (MoS2) nanoclusters, which are of interest as a model system in hydrodesulfurization catalysis. The STM gives the first real space images of the shape and edge structure of single-layer MoS2...

  10. Revisiting Jack Goody to Rethink Determinisms in Literacy Studies

    Science.gov (United States)

    Collin, Ross

    2013-01-01

    This article revisits Goody's arguments about literacy's influence on social arrangements, culture, cognition, economics, and other domains of existence. Whereas some of his arguments tend toward technological determinism (i.e., literacy causes change in the world), other of his arguments construe literacy as a force that shapes and is shaped by…

  11. A control center design revisited: learning from users’ appropriation

    DEFF Research Database (Denmark)

    Souza da Conceição, Carolina; Cordeiro, Cláudia

    2014-01-01

    This paper aims to present the lessons learned during a control center design project by revisiting another control center from the same company designed two and a half years before by the same project team. In light of the experience with the first project and its analysis, the designers and res...

  12. STM Studies of Spin-­Orbit Coupled Phases in Real-­ and Momentum-­Space

    Energy Technology Data Exchange (ETDEWEB)

    Madhavan, Vidya [Univ. of Illinois, Urbana, IL (United States)

    2016-10-17

    The recently discovered class of spin-orbit coupled materials with interesting topological character are fascinating both from fundamental as well as application point of view. Two striking examples are 3D topological insulators (TIs) and topological crystalline insulators (TCIs). These materials host linearly dispersing (Dirac like) surface states with an odd number of Dirac nodes and are predicted to carry a quantized half-integer value of the axion field. The non-trivial topological properties of TIs and TCIs arise from strong spin-orbit coupling leading to an inverted band structure; which also leads to the chiral spin texture in momentum space. In this project we used low temperature scanning tunneling microscopy (STM) and spectroscopy (STS) to study materials with topological phases in real- and momentum-space. We studied both single crystals and thin films of topological materials which are susceptible to being tuned by doping, strain or gating, allowing us to explore their physical properties in the most interesting regimes and set the stage for future technological applications. .

  13. PENGARUH GUIDE PERFORMANCE DAN QUALITY TOURISM SERVICE TERHADAP REVISIT INTENTION DI KEBUN RAYA BOGOR

    Directory of Open Access Journals (Sweden)

    Rian Andriani

    2016-11-01

    ABSTRACT Bogor Botanical Gardens is one of tourist destination in Bogor City, West Java, which the geographical in a strategic location between two big cities, Jakarta and Bandung. This location factor is can become an opportunity for Bogor Botanical Gardens to become a favorite tourist destination in Bogor City. Guide Performance and Quality Tourism Service is one of part of the tourism, so the researcher focus to Guide Performance and Quality Tourism Service To Revisit Intention in Bogor Botanical Gardens. In this research, the researcher used quantitative methode with descriptive verificative. The researcher used 100 respondent for a sample. In this research, the researcher used multiple linier regresion analysis with hypotesis test used determination coefficient test and F test. The classical assumption of this research is used normality test, multicollinearity test, heteroskedastisitas test and auto correlation test. In this research, the Guide Performance and Quality Tourism Service factors has an influence 33,2% of Revisit Intention in Bogor Botanical Garden. Keywords: Guide Performance, Quality Tourism Service and Revisit Intention

  14. Revisiting the concept of hepatosplenic schistosomiasis and its challenges using traditional and new tools

    Directory of Open Access Journals (Sweden)

    José Roberto Lambertucci

    2014-05-01

    Full Text Available Different aspects of hepatosplenic schistosomiasis are revisited here. Manson's schistosomiasis causes periportal fibrosis and portal hypertension in approximately 6% of infected subjects, usually with preservation of their hepatic function. The assessment of liver involvement is of major importance in determining the prognosis and risk of complications from schistosomiasis, such as upper digestive bleeding secondary to variceal rupture. For many years, the diagnosis of hepatosplenic schistosomiasis and liver fibrosis was made by abdominal palpation and the finding of liver and/or spleen enlargement. However, there is no consensus regarding the clinical parameters of the liver and spleen to be considered in this physical evaluation. For the last three decades, abdominal ultrasound (US has become the best imaging technique to evaluate liver fibrosis caused by schistosomiasis mansoni. However, US is a subjective procedure and is therefore examiner-dependent. Magnetic resonance imaging (MRI findings have provided valuable information in addition to ultrasound and clinical examination. The combination of a comprehensive history and physical examination, basic laboratory tests (a stool examination for Schistosoma mansoni eggs and a blood cell count, biomarkers for liver fibrosis/portal hypertension and imaging methods seem to offer the best approach for evaluating patients with this disease. In situations where research is involved or in patients with severe disease, MRI may be considered.

  15. Revisiting the Political Economy of Communication

    Directory of Open Access Journals (Sweden)

    Nicholas Garnham

    2014-02-01

    The task of the paper and the seminar was to revisit some of Nicholas Garnham’s ideas, writings and contributions to the study of the Political Economy of Communication and to reflect on the concepts, history, current status and perspectives of this field and the broader study of political economy today. The topics covered include Raymond Williams’ cultural materialism, Pierre Bourdieu’s sociology of culture, the debate between Political Economy and Cultural Studies, information society theory, Karl Marx’s theory and the critique of capitalism.

  16. A low-temperature scanning tunneling microscope capable of microscopy and spectroscopy in a Bitter magnet at up to 34 T.

    Science.gov (United States)

    Tao, W; Singh, S; Rossi, L; Gerritsen, J W; Hendriksen, B L M; Khajetoorians, A A; Christianen, P C M; Maan, J C; Zeitler, U; Bryant, B

    2017-09-01

    We present the design and performance of a cryogenic scanning tunneling microscope (STM) which operates inside a water-cooled Bitter magnet, which can attain a magnetic field of up to 38 T. Due to the high vibration environment generated by the magnet cooling water, a uniquely designed STM and a vibration damping system are required. The STM scan head is designed to be as compact and rigid as possible, to minimize the effect of vibrational noise as well as fit the size constraints of the Bitter magnet. The STM uses a differential screw mechanism for coarse tip-sample approach, and operates in helium exchange gas at cryogenic temperatures. The reliability and performance of the STM are demonstrated through topographic imaging and scanning tunneling spectroscopy on highly oriented pyrolytic graphite at T = 4.2 K and in magnetic fields up to 34 T.

  17. Sensing Current and Forces with SPM

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jeong Y.; Maier, Sabine; Hendriksen, Bas; Salmeron, Miquel

    2010-07-02

    Atomic force microscopy (AFM) and scanning tunneling microscopy (STM) are well established techniques to image surfaces and to probe material properties at the atomic and molecular scale. In this review, we show hybrid combinations of AFM and STM that bring together the best of two worlds: the simultaneous detection of atomic scale forces and conduction properties. We illustrate with several examples how the detection of forces during STM and the detection of currents during AFM can give valuable additional information of the nanoscale material properties.

  18. Revisiting renovascular imaging for renal sympathetic denervation: current techniques and applications

    Energy Technology Data Exchange (ETDEWEB)

    Pua, Uei; Tan, Cher Heng [Tan Tock Seng Hospital, Department of Diagnostic Radiology, Singapore (Singapore); Ho, Hee Hwa; Tan, Julian Ko Beng; Ong, Paul Jau Leong [Tan Tock Seng Hospital, Department of Cardiology, Singapore (Singapore)

    2014-08-28

    Renal sympathetic denervation (RDN) is an emerging technique in the treatment of resistant hypertension, most commonly performed using an endovascular approach. Clinical and anatomical criteria for RDN are well established and imaging plays an integral role in selecting patients with suitable anatomy, procedural planning and device selection. Nevertheless, the current body of literature surrounding imaging related to RDN remains limited. The purpose of this article is to illustrate the expectations and limitations of various imaging techniques, including Doppler ultrasound, CT angiography, MR angiography and newer techniques such as non-contrast MR angiography, in the context of RDN. (orig.)

  19. Revisiting renovascular imaging for renal sympathetic denervation: current techniques and applications

    International Nuclear Information System (INIS)

    Pua, Uei; Tan, Cher Heng; Ho, Hee Hwa; Tan, Julian Ko Beng; Ong, Paul Jau Leong

    2015-01-01

    Renal sympathetic denervation (RDN) is an emerging technique in the treatment of resistant hypertension, most commonly performed using an endovascular approach. Clinical and anatomical criteria for RDN are well established and imaging plays an integral role in selecting patients with suitable anatomy, procedural planning and device selection. Nevertheless, the current body of literature surrounding imaging related to RDN remains limited. The purpose of this article is to illustrate the expectations and limitations of various imaging techniques, including Doppler ultrasound, CT angiography, MR angiography and newer techniques such as non-contrast MR angiography, in the context of RDN. (orig.)

  20. Assessment of Spatiotemporal Fusion Algorithms for Planet and Worldview Images.

    Science.gov (United States)

    Kwan, Chiman; Zhu, Xiaolin; Gao, Feng; Chou, Bryan; Perez, Daniel; Li, Jiang; Shen, Yuzhong; Koperski, Krzysztof; Marchisio, Giovanni

    2018-03-31

    Although Worldview-2 (WV) images (non-pansharpened) have 2-m resolution, the re-visit times for the same areas may be seven days or more. In contrast, Planet images are collected using small satellites that can cover the whole Earth almost daily. However, the resolution of Planet images is 3.125 m. It would be ideal to fuse these two satellites images to generate high spatial resolution (2 m) and high temporal resolution (1 or 2 days) images for applications such as damage assessment, border monitoring, etc. that require quick decisions. In this paper, we evaluate three approaches to fusing Worldview (WV) and Planet images. These approaches are known as Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM), Flexible Spatiotemporal Data Fusion (FSDAF), and Hybrid Color Mapping (HCM), which have been applied to the fusion of MODIS and Landsat images in recent years. Experimental results using actual Planet and Worldview images demonstrated that the three aforementioned approaches have comparable performance and can all generate high quality prediction images.

  1. The vacuum structure, special relativity theory and quantum mechanics revisited: a field theory-no-geometry approach

    International Nuclear Information System (INIS)

    Bogolubov, N.N. Jr.; Prykarpatsky, A.K.; Ufuk Taneri

    2008-07-01

    The main fundamental principles characterizing the vacuum field structure are formulated and the modeling of the related vacuum medium and charged point particle dynamics by means of de- vised field theoretic tools are analyzed. The Maxwell electrodynamic theory is revisited and newly derived from the suggested vacuum field structure principles and the classical special relativity theory relationship between the energy and the corresponding point particle mass is revisited and newly obtained. The Lorentz force expression with respect to arbitrary non-inertial reference frames is revisited and discussed in detail, and some new interpretations of relations between the special relativity theory and quantum mechanics are presented. The famous quantum-mechanical Schroedinger type equations for a relativistic point particle in the external potential and magnetic fields within the quasiclassical approximation as the Planck constant (h/2π) → 0 and the light velocity c → ∞ are obtained. (author)

  2. K Mbugua The Problem of Hell Revisited pp93-103

    African Journals Online (AJOL)

    K Mbugua

    The Problem of Hell Revisited: Towards a Gentler Theology of Hell 93 ... One who, after He has killed, has authority to cast into hell; yes, I tell you, fear. Him! .... Suppose your spouse or parent or child goes to hell and you go to heaven.

  3. What matters to infrequent customers: a pragmatic approach to understanding perceived value and intention to revisit trendy coffee café.

    Science.gov (United States)

    Ting, Hiram; Thurasamy, Ramayah

    2016-01-01

    Notwithstanding the rise of trendy coffee café, little is done to investigate revisit intention towards the café in the context of developing markets. In particular, there is a lack of study which provides theoretical and practical explanation to the perceptions and behaviours of infrequent customers. Hence, the study aims to look into the subject matter by using the theory of reasoned action and social exchange theory as the underpinning basis. The framework proposed by Pine and Gilmore (Strat Leadersh 28:18-23, 2000), which asserts the importance of product quality, service quality and experience quality in a progressive manner, is used to decompose perceived value in the model so as to determine their effects on intention to revisit the café. Given the importance to gain practical insights into revisit intention of infrequent customers, pragmatism stance is assumed. Explanatory sequential mixed-method design is thus adopted whereby qualitative approach is used to confirm and complement quantitative findings. Self-administered questionnaire-based survey is first administered before personal interview is carried out at various cafés. Partial least squares structural equation modelling and content analysis are appropriated successively. In the quantitative findings, although product quality, service quality and experience quality are found to have positive effect on perceived value and revisit intention towards trendy coffee café, experience quality is found to have the greater effect than the others among the infrequent customers. The qualitative findings not only confirm their importance, but most importantly explain the favourable impressions they have at trendy coffee café based on their last in-store experience. While product and service quality might not necessary stimulate them to revisit trendy coffee café, experience quality driven by purposes of visit would likely affect their intention to revisit. As retaining customers is of utmost importance to

  4. Radiative corrections to neutrino deep inelastic scattering revisited

    International Nuclear Information System (INIS)

    Arbuzov, Andrej B.; Bardin, Dmitry Yu.; Kalinovskaya, Lidia V.

    2005-01-01

    Radiative corrections to neutrino deep inelastic scattering are revisited. One-loop electroweak corrections are re-calculated within the automatic SANC system. Terms with mass singularities are treated including higher order leading logarithmic corrections. Scheme dependence of corrections due to weak interactions is investigated. The results are implemented into the data analysis of the NOMAD experiment. The present theoretical accuracy in description of the process is discussed

  5. Doppler Processing with Ultra-Wideband (UWB) Radar Revisited

    Science.gov (United States)

    2018-01-01

    REPORT TYPE Technical Note 3. DATES COVERED (From - To) December 2017 4. TITLE AND SUBTITLE Doppler Processing with Ultra-Wideband (UWB) Radar...unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT This technical note revisits previous work performed at the US Army Research Laboratory related to...target considered previously is proportional to a delayed version of the transmitted signal, up to a complex constant factor. We write the received

  6. Road-Mapping the Way Forward for Sentinel-3 STM SAR-Mode Waveform Retracking over Water Surfaces

    Science.gov (United States)

    Benveniste, Jérôme; Cotton, David; Dinardo, Salvatore; Lucas, Bruno Manuel; Martin-Puig, Cristina; Ray, Chris; Clarizia, Maria Paola; Gommenginger, Christine

    2013-04-01

    . However, since the ultimate goal of the SAMOSA project is to deliver to the Sentinel-3 Surface Topography Mission Product and Algorithm Development (S-3 STM PAD) a Detailed Processing Model of a SAR ocean waveform re-tracker based on the best SAMOSA model to operationally re-track Sentinel-3 STM SAR-Mode L1b waveforms, the need for the full mathematical complexity of the SAMOSA2 model was re-evaluated. With this in mind, the SAMOSA team assessed a number of simplifications that can transform the SAMOSA2 model into a lighter, computationally more efficient, purely analytical formulation for input into the SAR re-tracker scheme for the Sentinel-3 STM PAD. The simplifications that have been considered involve the omission in the model of second order effects such as non-linear terms in the model, ocean surface skewness, and electromagnetic bias. Their impact has been evaluated. This SAMOSA3 model has the advantage to be a pure analytical solution, expressed by means of modified Bessel functions of first and second kind and returns no singularities for the full range of the gate bins. An extensive validation was performed. First equivalence between SAMOSA3, SAMOSA2 & SAMOSA1 models was confirmed and then a a sensitivity study on the input parameters and the re-tracking approach was carried out. Finally, the SAMOSA3 Model and re-tracker was applied to Cryosat-2 L1B SAR waveforms and the performance was studied as well as the sensitivity to mispointing. Two areas were chosen as representative of the high and low ocean dynamics regions, respectively the South Norwegian Sea and the Caspian Sea. Finally the SAMOSA3 output was validated against in situ wave buoy measurements. An overview of these results will be shown here.

  7. Dynamics of Shape Fluctuations of Quasi-spherical Vesicles Revisited

    DEFF Research Database (Denmark)

    Miao, L.; Lomholt, Michael Andersen; Kleis, J.

    2002-01-01

    In this paper, the dynamics of spontaneous shape fluctuations of a single, giant quasi-spherical vesicle formed from a single lipid species is revisited theoretically. A coherent physical theory for the dynamics is developed based on a number of fundamental principles and considerations, and a sy......In this paper, the dynamics of spontaneous shape fluctuations of a single, giant quasi-spherical vesicle formed from a single lipid species is revisited theoretically. A coherent physical theory for the dynamics is developed based on a number of fundamental principles and considerations...... of the phenomenological constants in a canonical continuum description of fluid lipid-bilayer membranes and shown the consequences of this new interpretation in terms of the characteristics of the dynamics of vesicle shape fluctuations. Moreover, we have used the systematic formulation of our theory as a framework...... against which we have discussed the previously existing theories and their discrepancies. Finally, we have made a systematic prediction about the system-dependent characteristics of the relaxation dynamics of shape fluctuations of quasi-spherical vesicles with a view of experimental studies...

  8. Revisiting Constructivist Teaching Methods in Ontario Colleges Preparing for Accreditation

    Science.gov (United States)

    Schultz, Rachel A.

    2015-01-01

    At the time of writing, the first community colleges in Ontario were preparing for transition to an accreditation model from an audit system. This paper revisits constructivist literature, arguing that a more pragmatic definition of constructivism effectively blends positivist and interactionist philosophies to achieve both student centred…

  9. Thorbecke Revisited : The Role of Doctrinaire Liberalism in Dutch Politics

    NARCIS (Netherlands)

    Drentje, Jan

    2011-01-01

    Thorbecke Revisited: The Role of Doctrinaire Liberalism in Dutch Politics In the political history of the nineteenth century Thorbecke played a crucial role. As the architect of the 1848 liberal constitutional reform he led three cabinets. In many ways he dominated the political discourse during the

  10. Revisiting Cementoblastoma with a Rare Case Presentation

    Directory of Open Access Journals (Sweden)

    Vijayanirmala Subramani

    2017-01-01

    Full Text Available Cementoblastoma is a rare benign odontogenic neoplasm which is characterized by the proliferation of cellular cementum. Diagnosis of cementoblastoma is challenging because of its protracted clinical, radiographic features, and bland histological appearance; most often cementoblastoma is often confused with other cementum and bone originated lesions. The aim of this article is to overview/revisit, approach the diagnosis of cementoblastoma, and also present a unique radiographic appearance of a cementoblastoma lesion associated with an impacted tooth.

  11. Auditory Short-Term Memory Capacity Correlates with Gray Matter Density in the Left Posterior STS in Cognitively Normal and Dyslexic Adults

    Science.gov (United States)

    Richardson, Fiona M.; Ramsden, Sue; Ellis, Caroline; Burnett, Stephanie; Megnin, Odette; Catmur, Caroline; Schofield, Tom M.; Leff, Alex P.; Price, Cathy J.

    2011-01-01

    A central feature of auditory STM is its item-limited processing capacity. We investigated whether auditory STM capacity correlated with regional gray and white matter in the structural MRI images from 74 healthy adults, 40 of whom had a prior diagnosis of developmental dyslexia whereas 34 had no history of any cognitive impairment. Using…

  12. Geo-oculus: high resolution multi-spectral earth imaging mission from geostationary orbit

    Science.gov (United States)

    Vaillon, L.; Schull, U.; Knigge, T.; Bevillon, C.

    2017-11-01

    Geo-Oculus is a GEO-based Earth observation mission studied by Astrium for ESA in 2008-2009 to complement the Sentinel missions, the space component of the GMES (Global Monitoring for Environment & Security). Indeed Earth imaging from geostationary orbit offers new functionalities not covered by existing LEO observation missions, like real-time monitoring and fast revisit capability of any location within the huge area in visibility of the satellite. This high revisit capability is exploited by the Meteosat meteorogical satellites, but with a spatial resolution (500 m nadir for the third generation) far from most of GMES needs (10 to 100 m). To reach such ground resolution from GEO orbit with adequate image quality, large aperture instruments (> 1 m) and high pointing stability (challenges of such missions. To address the requirements from the GMES user community, the Geo-Oculus mission is a combination of routine observations (daily systematic coverage of European coastal waters) with "on-demand" observation for event monitoring (e.g. disasters, fires and oil slicks). The instrument is a large aperture imaging telescope (1.5 m diameter) offering a nadir spatial sampling of 10.5 m (21 m worst case over Europe, below 52.5°N) in a PAN visible channel used for disaster monitoring. The 22 multi-spectral channels have resolutions over Europe ranging from 40 m in UV/VNIR (0.3 to 1 μm) to 750 m in TIR (10-12 μm).

  13. The structure of mixed H2O-OH monolayer films on Ru(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Tatarkhanov, M.; Fomin, E.; Salmeron, M.; Andersson, K.; Ogasawara, H.; Pettersson, L.G.M.; Nilsson, A.; Cerda, J.I.

    2008-10-20

    Scanning tunneling microscopy (STM) and x-ray absorption spectroscopy (XAS) have been used to study the structures produced by water on Ru(0001) at temperatures above 140 K. It was found that while undissociated water layers are metastable below 140 K, heating above this temperature produces drastic transformations whereby a fraction of the water molecules partially dissociate and form mixed H{sub 2}O-OH structures. XPS and XAS revealed the presence of hydroxyl groups with their O-H bond essentially parallel to the surface. STM images show that the mixed H{sub 2}O-OH structures consist of long narrow stripes aligned with the three crystallographic directions perpendicular to the close-packed atomic rows of the Ru(0001) substrate. The internal structure of the stripes is a honeycomb network of H-bonded water and hydroxyl species. We found that the metastable low temperature molecular phase can also be converted to a mixed H{sub 2}O-OH phase through excitation by the tunneling electrons when their energy is 0.5 eV or higher above the Fermi level. Structural models based on the STM images were used for Density Functional Theory optimizations of the stripe geometry. The optimized geometry was then utilized to calculate STM images for comparison with the experiment.

  14. New directions in scanning-tunneling microscopy

    International Nuclear Information System (INIS)

    Ferrell, T.L.; Warmack, R.J.; Reddick, R.C.

    1989-01-01

    The tunneling of electrons in scanning-tunneling microscopy (STM) has permitted imaging of the electronic distribution about individual atoms on surfaces. The need for use of conducting surfaces in STM limits its applicability, and new forms of scanning microscopy have emerged as a result of interest in poorly conducting samples. Atomic force microscopy has demonstrated that the force between a surface and a probe tip can be used to image selected materials. Now being developed are magnetic probe STM's and photon tunneling microscopes in which the probe is a sharpened optical fiber. Also of great interest presently is the measurement of differential conductance of surfaces using electron STM's. This method supplies spectral information and contrast enhancement in images. At present there remains much theoretical work to be carried out in order to better characterize related data on inelastic electron tunneling, and valuable insight may be gained from data being gathered on the local work function of materials. As matters stand today, the key problems lie in determining tip and contamination effects, preparation of samples, and understanding conductivity mechanisms in very thin materials on conducting substrates. Resolution of these problems and introduction of new forms of scanning microscopy may permit novel and important applications in biology as well as surface science

  15. Complete Genome sequence of Burkholderia phymatum STM815, a broad host range and efficient nitrogen-fixing symbiont of Mimosa species

    Energy Technology Data Exchange (ETDEWEB)

    Moulin, Lionel [UMR, France; Klonowska, Agnieszka [UMR, France; Caroline, Bournaud [UMR, France; Booth, Kristina [University of Massachusetts; Vriezen, Jan A.C. [University of Massachusetts; Melkonian, Remy [UMR, France; James, Euan [James Hutton Institute, Dundee, United Kingdom; Young, Peter W. [University of York, United Kingdom; Bena, Gilles [UMR, France; Hauser, Loren John [ORNL; Land, Miriam L [ORNL; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute; Bruce, David [Los Alamos National Laboratory (LANL); Chain, Patrick S. G. [Lawrence Livermore National Laboratory (LLNL); Copeland, A [U.S. Department of Energy, Joint Genome Institute; Pitluck, Sam [U.S. Department of Energy, Joint Genome Institute; Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute; Lizotte-Waniewski, Michelle [University of Massachusetts; Bristow, James [U.S. Department of Energy, Joint Genome Institute; Riley, Monica [Woods Hole Oceanographic Institution (WHOI), Woods Hole

    2014-01-01

    Burkholderia phymatum is a soil bacterium able to develop a nitrogen-fixing symbiosis with species of the legume genus Mimosa, and is frequently found associated specifically with Mimosa pudica. The type strain of the species, STM 815T, was isolated from a root nodule in French Guiana in 2000. The strain is an aerobic, motile, non-spore forming, Gram-negative rod, and is a highly competitive strain for nodulation compared to other Mimosa symbionts, as it also nodulates a broad range of other legume genera and species. The 8,676,562 bp genome is composed of two chromosomes (3,479,187 and 2,697,374 bp), a megaplasmid (1,904,893 bp) and a plasmid hosting the symbiotic functions (595,108 bp).

  16. In-situ STM study of phosphate adsorption on Cu(111), Au(111) and Cu/Au(111) electrodes

    DEFF Research Database (Denmark)

    Schlaup, Christian; Horch, Sebastian

    2013-01-01

    The interaction of Cu(111), Au(111) and Cu-covered Au(111) electrodes with a neutral phosphate buffer solution has been studied by means of cyclic voltammetry (CV) and in situ electrochemical scanning tunneling microscopy (EC-STM). Under low potential conditions, both the Cu(111) and the Au(111......) surface appear apparently adsorbate free, indicated by the presence of a (4×4) structure and the herringbone surface reconstruction, respectively. Upon potential increase, phosphate anions adsorb on both surfaces and for Cu(111) the formation of a (√3×√3)R30° structure is found, whereas on Au(111) a "(√3......×√7)" structure is formed. For a Cu-submonolayer on Au(111), coadsorption of phosphate anions leads to the formation of a (2×2) vacancy structure within an assumed pseudomorphic structure of the Cu-submonolayer with the phosphate anions occupying the vacancies. When desorbing the phosphate anions at low...

  17. NaCl islands decorated with 2D or 3D 3,4,9,10-perylene-tetracarboxylic-dianhydride nanostructures

    NARCIS (Netherlands)

    Sun, Xiaonan; Silly, Fabien

    2010-01-01

    The formation of PTCDA (3,4,9,10-perylene-tetracarboxylic-dianhydride) nanostrutures on Au(1 1 1)-(22 x root 3) covered with NaCl islands has been studied using scanning tunneling microscopy (STM). Atomically resolved STM images show that NaCl grows as (1 0 0)-terminated layers on Au(1 1 1)-(22 x

  18. Increased 30-Day Emergency Department Revisits Among Homeless Patients with Mental Health Conditions

    Directory of Open Access Journals (Sweden)

    Chun Nok Lam

    2016-09-01

    Full Text Available Introduction: Patients with mental health conditions frequently use emergency medical services. Many suffer from substance use and homelessness. If they use the emergency department (ED as their primary source of care, potentially preventable frequent ED revisits and hospital readmissions can worsen an already crowded healthcare system. However, the magnitude to which homelessness affects health service utilization among patients with mental health conditions remains unclear in the medical community. This study assessed the impact of homelessness on 30-day ED revisits and hospital readmissions among patients presenting with mental health conditions in an urban, safety-net hospital. Methods: We conducted a secondary analysis of administrative data on all adult ED visits in 2012 in an urban safety-net hospital. Patient demographics, mental health status, homelessness, insurance coverage, level of acuity, and ED disposition per ED visit were analyzed using multilevel modeling to control for multiple visits nested within patients. We performed multivariate logistic regressions to evaluate if homelessness moderated the likelihood of mental health patients’ 30-day ED revisits and hospital readmissions. Results: Study included 139,414 adult ED visits from 92,307 unique patients (43.5±15.1 years, 51.3% male, 68.2% Hispanic/Latino. Nearly 8% of patients presented with mental health conditions, while 4.6% were homeless at any time during the study period. Among patients with mental health conditions, being homeless contributed to an additional 28.0% increase in likelihood (4.28 to 5.48 odds of 30-day ED revisits and 38.2% increase in likelihood (2.04 to 2.82 odds of hospital readmission, compared to non-homeless, non-mental health (NHNM patients as the base category. Adjusted predicted probabilities showed that homeless patients presenting with mental health conditions have a 31.1% chance of returning to the ED within 30-day post discharge and a 3

  19. Computed tomography angiography in acute stroke (revisiting the 4Ps of imaging).

    Science.gov (United States)

    Varadharajan, Shriram; Saini, Jitender; Acharya, Ullas V; Gupta, Arun Kumar

    2016-02-01

    Imaging in acute stroke has traditionally focussed on the 4Ps-parenchyma, pipes, perfusion, and penumbra-and has increasingly relied upon advanced techniques including magnetic resonance imaging to evaluate such patients. However, as per European Magnetic Resonance Forum estimates, the availability of magnetic resonance imaging scanners for the general population in India (0.5 per million inhabitants) is quite low as compared to Europe (11 per million) and United States (35 per million), with most of them only present in urban cities. On the other hand, computed tomography (CT) is more widely available and has reduced scanning duration. Computed tomography angiography of cervical and intracranial vessels is relatively simpler to perform with extended coverage and can provide all pertinent information required in such patients. This imaging review will discuss relevant imaging findings on CT angiography in patients with acute ischemic stroke through illustrated cases. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Spherical gradient-index lenses as perfect imaging and maximum power transfer devices.

    Science.gov (United States)

    Gordon, J M

    2000-08-01

    Gradient-index lenses can be viewed from the perspectives of both imaging and nonimaging optics, that is, in terms of both image fidelity and achievable flux concentration. The simple class of gradient-index lenses with spherical symmetry, often referred to as modified Luneburg lenses, is revisited. An alternative derivation for established solutions is offered; the method of Fermat's strings and the principle of skewness conservation are invoked. Then these nominally perfect imaging devices are examined from the additional vantage point of power transfer, and the degree to which they realize the thermodynamic limit to flux concentration is determined. Finally, the spherical gradient-index lens of the fish eye is considered as a modified Luneburg lens optimized subject to material constraints.

  1. Anisotropic superconductivity in {beta}-(BDA-TTP){sub 2}SbF{sub 6}: STM spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, K. [Department of Physics, Hokkaido University, Sapporo 060-0810 (Japan)], E-mail: knmr@phys.sci.hokudai.ac.jp; Muraoka, R.; Matsunaga, N. [Department of Physics, Hokkaido University, Sapporo 060-0810 (Japan); Ichimura, K. [Division of Applied Physics, Hokkaido University, Sapporo 060-8628 (Japan); Yamada, J. [Division of Material Science, University of Hyogo, Hyogo 678-1297 (Japan)

    2009-03-01

    We have investigated the gap symmetry in the superconducting phase of {beta}-(BDA-TTP){sub 2}SbF{sub 6} with use of the scanning tunneling microscope (STM). The tunneling spectra obtained on the conducting surface show a clear superconducting gap structure. Its functional form is of V-shaped similarly to {kappa}-(BEDT-TTF){sub 2}X and suggests the anisotropic superconducting gap with line nodes. For lateral surfaces the shape of tunneling spectra varies from the U-shape with relatively large gap to the V-shape with small gap depending on the tunneling direction alternately twice between directional angle 0 and {pi}. From the analysis of conductance curve taking the k dependence of the tunneling probability into account, it is found that the gap has maximum near the a* and c* axes and the nodes appear along near a*+c* and the a-c* directions. These indicate that the d{sub x{sup 2}-y{sup 2}} like superconducting pair is formed in this system as the case of {kappa}-(BEDT-TTF){sub 2}X. This node direction is consistent with the theoretical prediction based on the spin fluctuation mechanism. However, the zero-bias conductance peak has not been observed yet.

  2. Implementasi Analog Front End Pada Sensor Kapasitif Untuk Pengaturan Kelembaban Menggunakan Mikrokontroller STM32

    Directory of Open Access Journals (Sweden)

    Rendy Setiawan

    2017-01-01

    Full Text Available Sensor kapasitif merupakan jenis sensor yang mengubah stimulus fisik menjadi perubahan kapasitansi. Pada sensor kapasitif, adanya stray capacitance atau kapasitansi parasitik pada sensor dapat menyebabkan kesalahan dalam pengukuran. Dalam aplikasi pengaturan kelembaban, dibutuhkan sistem pengukuran kelembaban dengan kesalahan minimum untuk mendapatkan nilai setting point dengan galat minimum. Maka diperlukan implementasi analog front end yang dapat meminimalisir kesalahan akibat stray capacitance pada sensor kapasitif untuk pengukuran kelembaban relatif. Pada sistem pengukuran sensor kapasitif ini, sensor dieksitasi dengan sinyal AC yang dihasilkan oleh generator sinyal pada frekuensi 10 KHz, kemudian diimplementasikan analog front end untuk mengondisikan sinyal dari sensor. Keluaran dari analog front end dikonversi menjadi sinyal DC menggunakan demodulator sinkron dan filter low pass lalu dikonversi menjadi data digital menggunakan ADC di mikrokontroller STM32. Hasil pengukuran yang didapatkan dengan implementasi analog front end kemudian kemudian gunakan untuk mengatur kelembaban pada sebuah plant growth chamber. Berdasarkan hasil dari pengujian, rangkaian analog front end dapat mengompensasi stray capacitance dengan kesalahan pembacaan nilai kapasitansi maksimal sebesar 4.2% pada kondisi stray capacitance sebesar 236,6pF, 174,3pF dan 115,7pF. Implementasi analog front end pada pengaturan kelembaban menghasilkan galat pada setting point maksimal sebesar 8.8% untuk nilai RH 75% dan 33%.

  3. Local Optical Spectroscopies for Subnanometer Spatial Resolution Chemical Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, Paul

    2014-01-20

    The evanescently coupled photon scanning tunneling microscopes (STMs) have special requirements in terms of stability and optical access. We have made substantial improvements to the stability, resolution, and noise floor of our custom-built visible-photon STM, and will translate these advances to our infrared instrument. Double vibration isolation of the STM base with a damping system achieved increased rigidity, giving high tunneling junction stability for long-duration and high-power illumination. Light frequency modulation with an optical chopper and phase-sensitive detection now enhance the signal-to-noise ratio of the tunneling junction during irradiation.

  4. Scanning tunneling microscopy studies of glucose oxidase on gold surface

    International Nuclear Information System (INIS)

    Losic, D.; Shapter, J.G.; Gooding, J.J.

    2002-01-01

    Full text: Three immobilization methods have been used for scanning tunneling microscopy (STM) studies of glucose oxidase (GOD) on gold. They are based on a) physical adsorption from solution, b) microcontact printing and c) covalent bonding onto self-assembled monolayers (SAM) of 3-mercaptopropionic acid (MPA). The STM images are used to provide information about the organization of individual GOD molecules and more densely packed monolayers of GOD on electrode surfaces, thus providing information of the role of interfacial structure on biosensor performance. The use of atomically flat gold substrates enables easy distinction of deposited enzyme features from the flat gold substrate. Microcontact printing is found to be a more reliable method than adsorption from solution for preparing individual GOD molecules on the gold surface STM images of printed samples reveal two different shapes of native GOD molecules. One is a butterfly shape with dimensions of 10 ± 1 nm x 6 ± 1 nm, assigned to the lying position of molecule while the second is an approximately spherical shape with dimensions of 6.5 ± 1 nm x 5 ± 1nm assigned to a standing position. Isolated clusters of 5 to 6 GOD molecules are also observed. With monolayer coverage, GOD molecules exhibit a tendency to organize themselves into a two dimensional array with adequate sample stability to obtain high-resolution STM images. Within these two-dimensional arrays are clearly seen repeating clusters of five to six enzyme molecules in a unit STM imaging of GOD monolayers covalently immobilized onto SAM (MPA) are considerably more difficult than when the enzyme is adsorbed directly onto the metal. Cluster structures are observed both high and low coverage despite the fact that native GOD is a negatively charged molecule. Copyright (2002) Australian Society for Electron Microscopy Inc

  5. Surface tension in soap films: revisiting a classic demonstration

    International Nuclear Information System (INIS)

    Behroozi, F

    2010-01-01

    We revisit a classic demonstration for surface tension in soap films and introduce a more striking variation of it. The demonstration shows how the film, pulling uniformly and normally on a loose string, transforms it into a circular arc under tension. The relationship between the surface tension and the string tension is analysed and presented in a useful graphical form. (letters and comments)

  6. The Neutrosophic Logic View to Schrodinger's Cat Paradox, Revisited

    Directory of Open Access Journals (Sweden)

    Florentin Smarandache

    2008-07-01

    Full Text Available The present article discusses Neutrosophic logic view to Schrodinger's cat paradox. We argue that this paradox involves some degree of indeterminacy (unknown which Neutrosophic logic can take into consideration, whereas other methods including Fuzzy logic cannot. To make this proposition clear, we revisit our previous paper by offering an illustration using modified coin tossing problem, known as Parrondo's game.

  7. Surface tension in soap films: revisiting a classic demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Behroozi, F [Department of Physics, University of Northern Iowa, Cedar Falls, IA 50614 (United States)], E-mail: behroozi@uni.edu

    2010-01-15

    We revisit a classic demonstration for surface tension in soap films and introduce a more striking variation of it. The demonstration shows how the film, pulling uniformly and normally on a loose string, transforms it into a circular arc under tension. The relationship between the surface tension and the string tension is analysed and presented in a useful graphical form. (letters and comments)

  8. Revisiting the quantum harmonic oscillator via unilateral Fourier transforms

    International Nuclear Information System (INIS)

    Nogueira, Pedro H F; Castro, Antonio S de

    2016-01-01

    The literature on the exponential Fourier approach to the one-dimensional quantum harmonic oscillator problem is revised and criticized. It is shown that the solution of this problem has been built on faulty premises. The problem is revisited via the Fourier sine and cosine transform method and the stationary states are properly determined by requiring definite parity and square-integrable eigenfunctions. (paper)

  9. Transport benchmarks for one-dimensional binary Markovian mixtures revisited

    International Nuclear Information System (INIS)

    Malvagi, F.

    2013-01-01

    The classic benchmarks for transport through a binary Markovian mixture are revisited to look at the probability distribution function of the chosen 'results': reflection, transmission and scalar flux. We argue that the knowledge of the ensemble averaged results is not sufficient for reliable predictions: a measure of the dispersion must also be obtained. An algorithm to estimate this dispersion is tested. (author)

  10. 18F-FDOPA PET/CT imaging of insulinoma revisited

    International Nuclear Information System (INIS)

    Imperiale, Alessio; Namer, Izzie-Jacques; Sebag, Frederic; Vix, Michel; Castinetti, Frederic; Kessler, Laurence; Moreau, Francois; Bachellier, Philippe; Guillet, Benjamin; Mundler, Olivier; Taieb, David

    2015-01-01

    18 F-FDOPA PET imaging is increasingly used in the work-up of patients with neuroendocrine tumours. It has been shown to be of limited value in localizing pancreatic insulin-secreting tumours in adults with hyperinsulinaemic hypoglycaemia (HH) mainly due to 18 F-FDOPA uptake by the whole pancreatic gland. The objective of this study was to review our experience with 18 F-FDOPA PET/CT imaging with carbidopa (CD) premedication in patients with HH in comparison with PET/CT studies performed without CD premedication in an independent population. A retrospective study including 16 HH patients who were investigated between January 2011 and December 2013 using 18 F-FDOPA PET/CT (17 examinations) in two academic endocrine tumour centres was conducted. All PET/CT examinations were performed under CD premedication (200 mg orally, 1 - 2 h prior to tracer injection). The PET/CT acquisition protocol included an early acquisition (5 min after 18 F-FDOPA injection) centred over the upper abdomen and a delayed whole-body acquisition starting 20 - 30 min later. An independent series of eight consecutive patients with HH and investigated before 2011 were considered for comparison. All patients had a reference whole-body PET/CT scan performed about 1 h after 18 F-FDOPA injection. In all cases, PET/CT was performed without CD premedication. In the study group, 18 F-FDOPA PET/CT with CD premedication was positive in 8 out of 11 patients with histologically proven insulinoma (73 %). All 18 F-FDOPA PET/CT-avid insulinomas were detected on early images and 5 of 11 (45 %) on delayed ones. The tumour/normal pancreas uptake ratio was not significantly different between early and delayed acquisitions. Considering all patients with HH, including those without imaging evidence of disease, the detection rate of the primary lesions using CD-assisted 18 F-FDOPA PET/CT was 53 %, showing 9 insulinomas in 17 studies performed. In the control group (without CD premedication, eight patients), the final

  11. A compact atomic force-scanning tunneling microscope for studying microelectronics and environmental aerosols

    International Nuclear Information System (INIS)

    Chen, G.

    1996-06-01

    This dissertation describes the characteristics and the construction of a compact atomic force/scanning tunneling microscope (AFM/STM). The basics and the method of preparing a tunneling junction between a chemically etched tunneling tip and a micro-manufactured cantilever is outlined by analyzing the forces between tunneling tip and cantilever as well as between force-sensing tip and sample surfaces. To our best knowledge this instrument is the first one using a commercial cantilever with only one piezoelectric tube carrying the whole tunneling sensor. The feedback control system has been optimized after a careful analysis of the electronic loop characteristics. The mode of operation has been determined by analyzing the dynamic characteristics of the scan heads and by investigating the time characteristics of the data acquisition system. The vibration isolation system has been calibrated by analyzing the characteristics of the damping setup and the stiffness of the scan head. The calculated results agree well with the measured ones. Also, a software package for data acquisition and real time display as well as for image processing and three-dimensional visualization has been developed. With this home-made software package, the images can be processed by means of a convolution filter, a Wiener filter and other 2-D FFT filters, and can be displayed in different ways. Atomic resolution images of highly oriented pyrolytic graphite (HOPG) and graphite surfaces have been obtained in AFM and STM mode. New theoretical explanations have been given for the observed anomalous STM and AFM images of graphite by calculating the asymmetric distribution of quantum conductance and tip-surface forces on a graphite surface. This not only resolved the theoretical puzzles of STM and AFM of graphite, but also revealed the relation between atomic force microscopy and scanning tunneling microscopy of graphite. Applications of STM and AFM to micro-electronic devices have been investigated

  12. Resolution of Reflection Seismic Data Revisited

    DEFF Research Database (Denmark)

    Hansen, Thomas Mejer; Mosegaard, Klaus; Zunino, Andrea

    The Rayleigh Principle states that the minimum separation between two reflectors that allows them to be visually separated is the separation where the wavelet maxima from the two superimposed reflections combine into one maximum. This happens around Δtres = λb/8, where λb is the predominant...... lower vertical resolution of reflection seismic data. In the following we will revisit think layer model and demonstrate that there is in practice no limit to the vertical resolution using the parameterization of Widess (1973), and that the vertical resolution is limited by the noise in the data...

  13. Scanning tunneling microscopy and atomic force microscopy: application to biology and technology.

    Science.gov (United States)

    Hansma, P K; Elings, V B; Marti, O; Bracker, C E

    1988-10-14

    The scanning tunneling microscope (STM) and the atomic force microscope (AFM) are scanning probe microscopes capable of resolving surface detail down to the atomic level. The potential of these microscopes for revealing subtle details of structure is illustrated by atomic resolution images including graphite, an organic conductor, an insulating layered compound, and individual adsorbed oxygen atoms on a semiconductor. Application of the STM for imaging biological materials directly has been hampered by the poor electron conductivity of most biological samples. The use of thin conductive metal coatings and replicas has made it possible to image some biological samples, as indicated by recently obtained images of a recA-DNA complex, a phospholipid bilayer, and an enzyme crystal. The potential of the AFM, which does not require a conductive sample, is shown with molecular resolution images of a nonconducting organic monolayer and an amino acid crystal that reveals individual methyl groups on the ends of the amino acids. Applications of these new microscopes to technology are demonstrated with images of an optical disk stamper, a diffraction grating, a thin-film magnetic recording head, and a diamond cutting tool. The STM has even been used to improve the quality of diffraction gratings and magnetic recording heads.

  14. Sloan Digital Sky Survey Photometric Calibration Revisited

    International Nuclear Information System (INIS)

    Marriner, John

    2012-01-01

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

  15. REVISITING A CLASSIC: THE PARKER–MOFFATT PROBLEM

    International Nuclear Information System (INIS)

    Pezzi, O.; Servidio, S.; Valentini, F.; Malara, F.; Veltri, P.; Parashar, T. N.; Yang, Y.; Matthaeus, W. H.; Vásconez, C. L.

    2017-01-01

    The interaction of two colliding Alfvén wave packets is described here by means of magnetohydrodynamics (MHD) and hybrid kinetic numerical simulations. The MHD evolution revisits the theoretical insights described by Moffatt, Parker, Kraichnan, Chandrasekhar, and Elsässer in which the oppositely propagating large-amplitude wave packets interact for a finite time, initiating turbulence. However, the extension to include compressive and kinetic effects, while maintaining the gross characteristics of the simpler classic formulation, also reveals intriguing features that go beyond the pure MHD treatment.

  16. REVISITING A CLASSIC: THE PARKER–MOFFATT PROBLEM

    Energy Technology Data Exchange (ETDEWEB)

    Pezzi, O.; Servidio, S.; Valentini, F.; Malara, F.; Veltri, P. [Dipartimento di Fisica, Università della Calabria, 87036 Rende (CS) (Italy); Parashar, T. N.; Yang, Y.; Matthaeus, W. H. [Department of Physics and Astronomy, University of Delaware, DE 19716 (United States); Vásconez, C. L. [Departamento de Física, Escuela Politécnica Nacional, Quito (Ecuador)

    2017-01-10

    The interaction of two colliding Alfvén wave packets is described here by means of magnetohydrodynamics (MHD) and hybrid kinetic numerical simulations. The MHD evolution revisits the theoretical insights described by Moffatt, Parker, Kraichnan, Chandrasekhar, and Elsässer in which the oppositely propagating large-amplitude wave packets interact for a finite time, initiating turbulence. However, the extension to include compressive and kinetic effects, while maintaining the gross characteristics of the simpler classic formulation, also reveals intriguing features that go beyond the pure MHD treatment.

  17. Sloan Digital Sky Survey Photometric Calibration Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Marriner, John; /Fermilab

    2012-06-29

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

  18. Neural organization of linguistic short-term memory is sensory modality-dependent: evidence from signed and spoken language.

    Science.gov (United States)

    Pa, Judy; Wilson, Stephen M; Pickell, Herbert; Bellugi, Ursula; Hickok, Gregory

    2008-12-01

    Despite decades of research, there is still disagreement regarding the nature of the information that is maintained in linguistic short-term memory (STM). Some authors argue for abstract phonological codes, whereas others argue for more general sensory traces. We assess these possibilities by investigating linguistic STM in two distinct sensory-motor modalities, spoken and signed language. Hearing bilingual participants (native in English and American Sign Language) performed equivalent STM tasks in both languages during functional magnetic resonance imaging. Distinct, sensory-specific activations were seen during the maintenance phase of the task for spoken versus signed language. These regions have been previously shown to respond to nonlinguistic sensory stimulation, suggesting that linguistic STM tasks recruit sensory-specific networks. However, maintenance-phase activations common to the two languages were also observed, implying some form of common process. We conclude that linguistic STM involves sensory-dependent neural networks, but suggest that sensory-independent neural networks may also exist.

  19. A combined scanning tunneling microscope-atomic layer deposition tool.

    Science.gov (United States)

    Mack, James F; Van Stockum, Philip B; Iwadate, Hitoshi; Prinz, Fritz B

    2011-12-01

    We have built a combined scanning tunneling microscope-atomic layer deposition (STM-ALD) tool that performs in situ imaging of deposition. It operates from room temperature up to 200 °C, and at pressures from 1 × 10(-6) Torr to 1 × 10(-2) Torr. The STM-ALD system has a complete passive vibration isolation system that counteracts both seismic and acoustic excitations. The instrument can be used as an observation tool to monitor the initial growth phases of ALD in situ, as well as a nanofabrication tool by applying an electric field with the tip to laterally pattern deposition. In this paper, we describe the design of the tool and demonstrate its capability for atomic resolution STM imaging, atomic layer deposition, and the combination of the two techniques for in situ characterization of deposition.

  20. Electron transfer and redox metalloenzyme catalysis at the single-molecule level

    DEFF Research Database (Denmark)

    Hansen, Allan Glargaard; Zhang, Jingdong; Christensen, Hans Erik Mølager

    2004-01-01

    transfer (ET). Image interpretation requires, however, theoretical support, as STM represents both electronic and topographic features. Molecules with accessible redox levels offer other insight into electron tunneling mechanisms, addressed in detail for ET metalloproteins. We present here in situ STM...... of the blue redox metalloenzyme copper nitrite reductase (Achromobacter xylosoxidans, AxCuNiR) on Au(111) electrode surfaces modified by a self-assembled cysteamine monolayer. AxCuNiR displays strong nitrite reduction waves in this environment. AxCuNiR/cysteamine/ Au(111) surfaces were imaged at KNO2...

  1. A cryogen-free low temperature scanning tunneling microscope capable of inelastic electron tunneling spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shuai; Huang, Di [State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (MOE), and Department of Physics, Fudan University, Shanghai 200433 (China); Wu, Shiwei, E-mail: swwu@fudan.edu.cn [State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (MOE), and Department of Physics, Fudan University, Shanghai 200433 (China); Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China)

    2016-06-15

    The design and performance of a cryogen-free low temperature scanning tunneling microscope (STM) housed in ultrahigh vacuum (UHV) are reported. The cryogen-free design was done by directly integrating a Gifford-McMahon cycle cryocooler to a Besocke-type STM, and the vibration isolation was achieved by using a two-stage rubber bellow between the cryocooler and a UHV-STM interface with helium exchange gas cooling. A base temperature of 15 K at the STM was achieved, with a possibility to further decrease by using a cryocooler with higher cooling power and adding additional low temperature stage under the exchange gas interface. Atomically sharp STM images and high resolution dI/dV spectra on various samples were demonstrated. Furthermore, we reported the inelastic tunneling spectroscopy on a single carbon monoxide molecule adsorbed on Ag(110) surface with a cryogen-free STM for the first time. Being totally cryogen-free, the system not only saves the running cost significantly but also enables uninterrupted data acquisitions and variable temperature measurements with much ease. In addition, the system is capable of coupling light to the STM junction by a pair of lens inside the UHV chamber. We expect that these enhanced capabilities could further broaden our views to the atomic-scale world.

  2. A cryogen-free low temperature scanning tunneling microscope capable of inelastic electron tunneling spectroscopy.

    Science.gov (United States)

    Zhang, Shuai; Huang, Di; Wu, Shiwei

    2016-06-01

    The design and performance of a cryogen-free low temperature scanning tunneling microscope (STM) housed in ultrahigh vacuum (UHV) are reported. The cryogen-free design was done by directly integrating a Gifford-McMahon cycle cryocooler to a Besocke-type STM, and the vibration isolation was achieved by using a two-stage rubber bellow between the cryocooler and a UHV-STM interface with helium exchange gas cooling. A base temperature of 15 K at the STM was achieved, with a possibility to further decrease by using a cryocooler with higher cooling power and adding additional low temperature stage under the exchange gas interface. Atomically sharp STM images and high resolution dI/dV spectra on various samples were demonstrated. Furthermore, we reported the inelastic tunneling spectroscopy on a single carbon monoxide molecule adsorbed on Ag(110) surface with a cryogen-free STM for the first time. Being totally cryogen-free, the system not only saves the running cost significantly but also enables uninterrupted data acquisitions and variable temperature measurements with much ease. In addition, the system is capable of coupling light to the STM junction by a pair of lens inside the UHV chamber. We expect that these enhanced capabilities could further broaden our views to the atomic-scale world.

  3. Advances in computed radiography systems and their physical imaging characteristics

    International Nuclear Information System (INIS)

    Cowen, A.R.; Davies, A.G.; Kengyelics, S.M.

    2007-01-01

    Radiological imaging is progressing towards an all-digital future, across the spectrum of medical imaging techniques. Computed radiography (CR) has provided a ready pathway from screen film to digital radiography and a convenient entry point to PACS. This review briefly revisits the principles of modern CR systems and their physical imaging characteristics. Wide dynamic range and digital image enhancement are well-established benefits of CR, which lend themselves to improved image presentation and reduced rates of repeat exposures. However, in its original form CR offered limited scope for reducing the radiation dose per radiographic exposure, compared with screen film. Recent innovations in CR, including the use of dual-sided image readout and channelled storage phosphor have eased these concerns. For example, introduction of these technologies has improved detective quantum efficiency (DQE) by approximately 50 and 100%, respectively, compared with standard CR. As a result CR currently affords greater scope for reducing patient dose, and provides a more substantive challenge to the new solid-state, flat-panel, digital radiography detectors

  4. Note: Low-temperature scanning tunneling microscope with detachable scanner and reliable transfer mechanism for tip and sample exchange.

    Science.gov (United States)

    Ge, Weifeng; Wang, Jihao; Wang, Junting; Zhang, Jing; Hou, Yubin; Lu, Qingyou

    2017-12-01

    A homebuilt low-temperature scanning tunneling microscope (STM) featuring a detachable scanner based on a double slider design, along with a reliable transfer mechanism for tip and sample exchange, is present. The coarse motor is decoupled from the scanner, which prevents the motor instabilities including vibrations and drifts from entering the tip-sample loop and thus improves the performance of the STM. In addition, in situ exchange of tips and samples can be implemented easily and reliably using a winch-type transfer mechanism. Atomically resolved images on graphite are demonstrated to show the performance of the proposed STM.

  5. Revisiting deforestation in Africa (1990–2010): One more lost ...

    African Journals Online (AJOL)

    This spotlight revisits the dynamics and prognosis outlined in the late 1980's published in Déforestation en Afrique. This book on deforestation in Africa utilized available statistical data from the 1980's and was a pioneering self - styled attempt to provide a holistic viewpoint of the ongoing trends pertaining to deforestation in ...

  6. Revisiting Individual Creativity Assessment: Triangulation in Subjective and Objective Assessment Methods

    Science.gov (United States)

    Park, Namgyoo K.; Chun, Monica Youngshin; Lee, Jinju

    2016-01-01

    Compared to the significant development of creativity studies, individual creativity research has not reached a meaningful consensus regarding the most valid and reliable method for assessing individual creativity. This study revisited 2 of the most popular methods for assessing individual creativity: subjective and objective methods. This study…

  7. Structure of cleaved (001) USb2 single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shao-ping [Los Alamos National Laboratory; Hawley, Marilyn [Los Alamos National Laboratory; Bauer, Eric D [Los Alamos National Laboratory; Stockum, Phil B [STANFORD UNIV.; Manoharan, Hari C [STANFORD UNIV

    2009-01-01

    We have achieved what we believe to be the first atomic resolution STM images for a uranium compound taken at room temperature. The a, b, and c lattice parameters in the images confirm that the USb{sub 2} crystals cleave on the (001) basal plane as expected. The a and b dimensions were equal, with the atoms arranged in a cubic pattern. Our calculations indicate a symmetric cut between Sb planes to be the most favorable cleavage plane and U atoms to be responsible for most of the DOS measured by STM. Some strange features observed in the STM will be discussed in conjunction with ab initio calculations. The purpose of this work is to demonstrate the power of scanning tunneling microscopy (STM) techniques combined with a theoretical underpinning to determine the surface atomic structure and properties of actinide materials, such as the quasi 2-dimensional uranium dipnictide USb{sub 2} single crystal, thereby contributing to the understanding of their surface structural and electronic properties. The members of this interesting UX{sub 2} (X=P, As, Sb, Bi) series of compounds display dual localized and itinerant 5f electron behavior within the same compound due to the hybridization of the 5f orbitals with the conduction band. With the exception of UO{sub 2}, which has to be studied at elevated temperature to generate enough carriers for STM imaging, STM techniques have not been applied successfully to the characterization of the surface atomic structure of any other single crystal actinide compound, to the best of our knowledge. However, STM has been used to a limited extent for the study of some cerium compounds. STM probes electronic properties at the atomic level and can directly provide information about the local density of filled and empty states (LDOS) states simultaneously. A STM topograph provides the local atomic arrangement and spacing of the atoms on the surface, local defect structures (e.g. steps, vacancies, and kink sites) and the presence of contaminants

  8. Logistics Innovation Process Revisited

    DEFF Research Database (Denmark)

    Gammelgaard, Britta; Su, Shong-Iee Ivan; Yang, Su-Lan

    2011-01-01

    Purpose – The purpose of this paper is to learn more about logistics innovation processes and their implications for the focal organization as well as the supply chain, especially suppliers. Design/methodology/approach – The empirical basis of the study is a longitudinal action research project...... that was triggered by the practical needs of new ways of handling material flows of a hospital. This approach made it possible to revisit theory on logistics innovation process. Findings – Apart from the tangible benefits reported to the case hospital, five findings can be extracted from this study: the logistics...... innovation process model may include not just customers but also suppliers; logistics innovation in buyer-supplier relations may serve as an alternative to outsourcing; logistics innovation processes are dynamic and may improve supplier partnerships; logistics innovations in the supply chain are as dependent...

  9. Life quality index revisited

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager

    2004-01-01

    The derivation of the life quality index (LQI) is revisited for a revision. This revision takes into account the unpaid but necessary work time needed to stay alive in clean and healthy conditions to be fit for effective wealth producing work and to enjoyable free time. Dimension analysis...... at birth should not vary between countries. Finally the distributional assumptions are relaxed as compared to the assumptions made in an earlier work by the author. These assumptions concern the calculation of the life expectancy change due to the removal of an accident source. Moreover a simple public...... consistency problems with the standard power function expression of the LQI are pointed out. It is emphasized that the combination coefficient in the convex differential combination between the relative differential of the gross domestic product per capita and the relative differential of the expected life...

  10. Klein's double discontinuity revisited

    DEFF Research Database (Denmark)

    Winsløw, Carl; Grønbæk, Niels

    2014-01-01

    Much effort and research has been invested into understanding and bridging the ‘gaps’ which many students experience in terms of contents and expectations as they begin university studies with a heavy component of mathematics, typically in the form of calculus courses. We have several studies...... of bridging measures, success rates and many other aspects of these “entrance transition” problems. In this paper, we consider the inverse transition, experienced by university students as they revisit core parts of high school mathematics (in particular, calculus) after completing the undergraduate...... mathematics courses which are mandatory to become a high school teacher of mathematics. To what extent does the “advanced” experience enable them to approach the high school calculus in a deeper and more autonomous way ? To what extent can “capstone” courses support such an approach ? How could it be hindered...

  11. Characteristics, finite element analysis, test description, and preliminary test results of the STM4-120 kinematic Stirling engine

    Science.gov (United States)

    Linker, K. L.; Rawlinson, K. S.; Smith, G.

    1991-10-01

    The Department of Energy's Solar Thermal Program has, as one of its program elements, the development and evaluation of conversion device technologies applicable to dish-electric systems. The primary research and development combines a conversion device (heat engine), solar receiver, and generator mounted at the focus of a parabolic dish concentrator. The Stirling-cycle heat engine was identified as the conversion device for dish-electric with the most potential for meeting the program's goals for efficiency, reliability, and installed cost. To advance the technology toward commercialization, Sandia National Laboratories has acquired a Stirling Thermal Motors, Inc. kinematic Stirling engine, STM4-120, for evaluation. The engine is being bench-tested at Sandia's Engine Test Facility and will be combined later with a solar receiver for on-sun evaluation. This report presents the engine characteristics, finite element analyses of critical engine components, test system layout, instrumentation, and preliminary performance results from the bench test.

  12. Rereading Albert B. Lord's The Singer of Tales . Revisiting the ...

    African Journals Online (AJOL)

    Access to a fresh set of video-recordings of Sesotho praise-poetry made in the year 2000 enabled the author to revisit his adaptation of Albert Lord's definition of the formula as a dynamic compositional device that the oral poet utilizes during delivery. The basic adaptation made in 1983 pertains to heroic praises (dithoko tsa ...

  13. Re-Visit to the School Nurse and Adolescents' Medicine Use

    Science.gov (United States)

    Borup, Ina K.; Andersen, Anette; Holstein, Bjorn E.

    2011-01-01

    Objective: To examine if students who re-visit the school nurse use medicines differently than other students when exposed to aches and psychological problems. Methods: The study includes all 11-, 13- and 15-year-old students from a random sample of schools in Denmark, response rate 87 per cent, n = 5,205. The data collection followed the…

  14. Revisiting adoption of high transmission PSM: pros, cons and path forward

    Science.gov (United States)

    Ma, Z. Mark; McDonald, Steve; Progler, Chris

    2009-12-01

    High transmission attenuated phase shift masks (Hi-T PSM) have been successfully applied in volume manufacturing for certain memory devices. Moreover, numerous studies have shown the potential benefits of Hi-T PSM for specific lithography applications. In this paper, the potential for extending Hi-T PSM to logic devices, is revisited with an emphasis on understanding layout, transmission, and manufacturing of Hi-T PSM versus traditional 6% embedded attenuated phase shift mask (EAPSM). Simulations on various layouts show Hi-T PSM has advantage over EAPSM in low duty cycle line patterns and high duty cycle space patterns. The overall process window can be enhanced when Hi- T PSM is combined with optimized optical proximity correction (OPC), sub-resolution assist features (SRAF), and source illumination. Therefore, Hi-T PSM may be a viable and lower cost alternative to other complex resolution enhancement technology (RET) approaches. Aerial image measurement system (AIMS) results on test masks, based on an inverse lithography technology (ILT) generated layout, confirm the simulation results. New advancement in high transmission blanks also make low topography Hi-T PSM a reality, which can minimize scattering effects in high NA lithography.

  15. In silico simulations of tunneling barrier measurements for molecular orbital-mediated junctions: A molecular orbital theory approach to scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Terryn, Raymond J.; Sriraman, Krishnan; Olson, Joel A., E-mail: jolson@fit.edu; Baum, J. Clayton, E-mail: cbaum@fit.edu [Department of Chemistry, Florida Institute of Technology, 150 West University Boulevard, Melbourne, Florida 32901 (United States); Novak, Mark J. [Department of Chemistry and Applied Biological Sciences, South Dakota School of Mines and Technology, 501 E. Saint Joseph Street, Rapid City, South Dakota 57701 (United States)

    2016-09-15

    A new simulator for scanning tunneling microscopy (STM) is presented based on the linear combination of atomic orbitals molecular orbital (LCAO-MO) approximation for the effective tunneling Hamiltonian, which leads to the convolution integral when applied to the tip interaction with the sample. This approach intrinsically includes the structure of the STM tip. Through this mechanical emulation and the tip-inclusive convolution model, dI/dz images for molecular orbitals (which are closely associated with apparent barrier height, ϕ{sub ap}) are reported for the first time. For molecular adsorbates whose experimental topographic images correspond well to isolated-molecule quantum chemistry calculations, the simulator makes accurate predictions, as illustrated by various cases. Distortions in these images due to the tip are shown to be in accord with those observed experimentally and predicted by other ab initio considerations of tip structure. Simulations of the tunneling current dI/dz images are in strong agreement with experiment. The theoretical framework provides a solid foundation which may be applied to LCAO cluster models of adsorbate–substrate systems, and is extendable to emulate several aspects of functional STM operation.

  16. In silico simulations of tunneling barrier measurements for molecular orbital-mediated junctions: A molecular orbital theory approach to scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Terryn, Raymond J.; Sriraman, Krishnan; Olson, Joel A.; Baum, J. Clayton; Novak, Mark J.

    2016-01-01

    A new simulator for scanning tunneling microscopy (STM) is presented based on the linear combination of atomic orbitals molecular orbital (LCAO-MO) approximation for the effective tunneling Hamiltonian, which leads to the convolution integral when applied to the tip interaction with the sample. This approach intrinsically includes the structure of the STM tip. Through this mechanical emulation and the tip-inclusive convolution model, dI/dz images for molecular orbitals (which are closely associated with apparent barrier height, ϕ_a_p) are reported for the first time. For molecular adsorbates whose experimental topographic images correspond well to isolated-molecule quantum chemistry calculations, the simulator makes accurate predictions, as illustrated by various cases. Distortions in these images due to the tip are shown to be in accord with those observed experimentally and predicted by other ab initio considerations of tip structure. Simulations of the tunneling current dI/dz images are in strong agreement with experiment. The theoretical framework provides a solid foundation which may be applied to LCAO cluster models of adsorbate–substrate systems, and is extendable to emulate several aspects of functional STM operation.

  17. An experimental study of furan adsorption and decomposition on vicinal palladium surfaces using scanning tunneling microscopy

    Science.gov (United States)

    Loui, A.; Chiang, S.

    2018-04-01

    The intact adsorption and decomposition of furan (C4H4O) on vicinal palladium surfaces with (111)-oriented terraces has been studied by scanning tunneling microscopy (STM) over a range of temperatures. STM images at 225 K show that furan molecules lie flat and prefer to adsorb at upper step edges. At 225 K, furan molecules adsorbed on "narrow" terraces of 20 to 45 Å in width appear to diffuse more readily than those adsorbed on "wide" terraces of 160 to 220 Å. A distinct population of smaller features appears in STM images on "narrow" terraces at 288 K and on "wide" terraces at 415 K and is identified with the C3H3 decomposition product, agreeing with prior studies which demonstrated that furan dissociates on Pd(111) to yield carbon monoxide (CO) and a C3H3 moiety in the 280 to 320 K range. Based on our direct visualization of this reaction using STM, we propose a spatial mechanism in which adsorption of furan at upper step edges allows catalysis of the dissociation, followed by diffusion of the product to lower step edges.

  18. Sample mounting and transfer for coupling an ultrahigh vacuum variable temperature beetle scanning tunneling microscope with conventional surface probes

    International Nuclear Information System (INIS)

    Nafisi, Kourosh; Ranau, Werner; Hemminger, John C.

    2001-01-01

    We present a new ultrahigh vacuum (UHV) chamber for surface analysis and microscopy at controlled, variable temperatures. The new instrument allows surface analysis with Auger electron spectroscopy, low energy electron diffraction, quadrupole mass spectrometer, argon ion sputtering gun, and a variable temperature scanning tunneling microscope (VT-STM). In this system, we introduce a novel procedure for transferring a sample off a conventional UHV manipulator and onto a scanning tunneling microscope in the conventional ''beetle'' geometry, without disconnecting the heating or thermocouple wires. The microscope, a modified version of the Besocke beetle microscope, is mounted on a 2.75 in. outer diameter UHV flange and is directly attached to the base of the chamber. The sample is attached to a tripod sample holder that is held by the main manipulator. Under UHV conditions the tripod sample holder can be removed from the main manipulator and placed onto the STM. The VT-STM has the capability of acquiring images between the temperature range of 180--500 K. The performance of the chamber is demonstrated here by producing an ordered array of island vacancy defects on a Pt(111) surface and obtaining STM images of these defects

  19. A 30 mK, 13.5 T scanning tunneling microscope with two independent tips

    Energy Technology Data Exchange (ETDEWEB)

    Roychowdhury, Anita [Laboratory for Physical Sciences, College Park, Maryland 20742 (United States); Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, Maryland 20740 (United States); Gubrud, M. A.; Dana, R.; Dreyer, M. [Laboratory for Physical Sciences, College Park, Maryland 20742 (United States); Anderson, J. R.; Lobb, C. J.; Wellstood, F. C. [Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, Maryland 20740 (United States)

    2014-04-15

    We describe the design, construction, and performance of an ultra-low temperature, high-field scanning tunneling microscope (STM) with two independent tips. The STM is mounted on a dilution refrigerator and operates at a base temperature of 30 mK with magnetic fields of up to 13.5 T. We focus on the design of the two-tip STM head, as well as the sample transfer mechanism, which allows in situ transfer from an ultra high vacuum preparation chamber while the STM is at 1.5 K. Other design details such as the vibration isolation and rf-filtered wiring are also described. Their effectiveness is demonstrated via spectral current noise characteristics and the root mean square roughness of atomic resolution images. The high-field capability is shown by the magnetic field dependence of the superconducting gap of Cu{sub x}Bi{sub 2}Se{sub 3}. Finally, we present images and spectroscopy taken with superconducting Nb tips with the refrigerator at 35 mK that indicate that the effective temperature of our tips/sample is approximately 184 mK, corresponding to an energy resolution of 16 μeV.

  20. A 30 mK, 13.5 T scanning tunneling microscope with two independent tips.

    Science.gov (United States)

    Roychowdhury, Anita; Gubrud, M A; Dana, R; Anderson, J R; Lobb, C J; Wellstood, F C; Dreyer, M

    2014-04-01

    We describe the design, construction, and performance of an ultra-low temperature, high-field scanning tunneling microscope (STM) with two independent tips. The STM is mounted on a dilution refrigerator and operates at a base temperature of 30 mK with magnetic fields of up to 13.5 T. We focus on the design of the two-tip STM head, as well as the sample transfer mechanism, which allows in situ transfer from an ultra high vacuum preparation chamber while the STM is at 1.5 K. Other design details such as the vibration isolation and rf-filtered wiring are also described. Their effectiveness is demonstrated via spectral current noise characteristics and the root mean square roughness of atomic resolution images. The high-field capability is shown by the magnetic field dependence of the superconducting gap of CuxBi2Se3. Finally, we present images and spectroscopy taken with superconducting Nb tips with the refrigerator at 35 mK that indicate that the effective temperature of our tips/sample is approximately 184 mK, corresponding to an energy resolution of 16 μeV.

  1. LT-STM/STS observation of definite superconducting gap states on the multistage crystal surface of Bi2Sr2CaCu2O8+x

    International Nuclear Information System (INIS)

    Murakami, Hironaru; Aoki, Ryozo

    1996-01-01

    Low temperature STM/STS observations have been carried out on cleaved BSCCO crystal surfaces. The authors have succeeded in detection of a special layer, probably a CuO 2 or Ca layer exposed on the surface. The STS spectrum which was reproducibly observed on this special site shows a considerably anisotropic but distinct superconducting gap structure with a definite and flat gap bottom region. This gap structure shows significantly different characteristic from another gap structure observed on the BiO layer, which shows a rounded shape at the gap bottom region without any indication of a finite gap state

  2. Scanning tunneling spectroscopy on vortex cores in high-T{sub c} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Hoogenboom, B.W.; Maggio-Aprile, I.; Fischer, Oe. [Geneva Univ. (Switzerland). Dept. de Physique de la Matiere Condensee; Renner, C. [NEC Research Inst., Princeton, NJ (United States)

    2002-07-01

    Scanning tunneling spectroscopy (STS) with its unique capacity for tunneling spectroscopy with sub-nanometer spatial resolution, has opened new ways to look at the flux lines and their distribution in superconductors. In contrast to all other imaging techniques, which are sensitive to the local magnetic field, STM relies on local changes in the density of states near the Fermi level to generate a real space image of the vortex distribution. It is thus sensitive to the vortex cores, which in high temperature superconductors have a size approaching the interatomic distances. The small size of the vortex cores and the anisotropic character of the high temperature superconductors allow pinning to play a large role in determining the vortex core positions. Vortex hopping between different pinning sites, again down to a sub-nanometer scale, has been studied by STM imaging as a function of time. These studies give microscopic indications for quantum tunneling of vortices. Moreover, STM provides new insights into the detailed electronic vortex core structure, revealing localized quasiparticles. (orig.)

  3. The Peter Effect Revisited: Reading Habits and Attitudes of College Students

    Science.gov (United States)

    Applegate, Anthony J.; Applegate, Mary DeKonty; Mercantini, Martha A.; McGeehan, Catherine M.; Cobb, Jeanne B.; DeBoy, Joanne R.; Modla, Virginia B.; Lewinski, Kimberly E.

    2014-01-01

    Certainly a primary goal of literacy education is the creation of avid, enthusiastic, and highly motivated readers. However, in this article revisiting the Peter Effect (Applegate & Applegate, 2004), researchers surveyed more than 1,000 college sophomores and found strikingly low levels of enthusiasm for reading. Only 46.6% of surveyed…

  4. A proximal retarding field analyzer for scanning probe energy loss spectroscopy

    Science.gov (United States)

    Bauer, Karl; Murphy, Shane; Palmer, Richard E.

    2017-03-01

    A compact proximal retarding field analyzer for scanning probe energy loss spectroscopy measurements is described. Using the scanning tunneling microscope (STM) tip as a field emission (FE) electron source in conjunction with this analyzer, which is placed at a glancing angle to the surface plane, FE sample current and electron reflectivity imaging may be performed simultaneously. This is demonstrated in measurements of Ag nanostructures prepared on graphite by electron-beam lithography, where a material contrast of 13% is observed, with a lateral resolution of 25 nm, between the silver and graphite in electron reflectivity images. Topological contrast mechanisms such as edge enhancement and shadowing are also observed, giving rise to additional features in the electron reflectivity images. The same instrument configuration has been used to measure electron energy loss spectra on bare graphite, where the zero loss peak, π band plasmon loss peak and secondary electron peaks are observed. Using this simple and compact analyzer an STM, with sufficient open access to the tip-sample junction, may easily be augmented to provide simultaneous elemental and topographic mapping, supplementing STM image measurements with FE sample current and electron reflectivity images, as well as electron energy loss spectroscopy measurements, in the same instrument.

  5. Ambulatory thyroidectomy: A multistate study of revisits and complications

    OpenAIRE

    Orosco, RK; Lin, HW; Bhattacharyya, N

    2015-01-01

    © 2015 American Academy of Otolaryngology - Head and Neck Surgery Foundation. Objective. Determine rates and reasons for revisits after ambulatory adult thyroidectomy. Study Design. Cross-sectional analysis of multistate ambulatory surgery and hospital databases. Setting. Ambulatory surgery data from the State Ambulatory Surgery Databases of California, Florida, Iowa, and New York for calendar years 2010 and 2011. Subjects and Methods. Ambulatory thyroidectomy cases were linked to state ambul...

  6. Recoding between two types of STM representation revealed by the dynamics of memory search.

    Science.gov (United States)

    Leszczyński, Marcin; Myers, Nicholas E; Akyürek, Elkan G; Schubö, Anna

    2012-03-01

    Visual STM (VSTM) is thought to be related to visual attention in several ways. Attention controls access to VSTM during memory encoding and plays a role in the maintenance of stored information by strengthening memorized content. We investigated the involvement of visual attention in recall from VSTM. In two experiments, we measured electrophysiological markers of attention in a memory search task with varying intervals between VSTM encoding and recall, and so we were able to track recoding of representations in memory. Results confirmed the involvement of attention in VSTM recall. However, the amplitude of the N2pc and N3rs components, which mark orienting of attention and search within VSTM, decreased as a function of delay. Conversely, the amplitude of the P3 and sustained posterior contralateral negativity components increased as a function of delay, effectively the opposite of the N2pc and N3rs modulations. These effects were only observed when verbal memory was not taxed. Thus, the results suggested that gradual recoding from visuospatial orienting of attention into verbal recall mechanisms takes place from short to long retention intervals. Interestingly, recall at longer delays was faster than at short delays, indicating that verbal representation is coupled with faster responses. These results extend the orienting-of-attention hypothesis by including an account of representational recoding during short-term consolidation and its consequences for recall from VSTM.

  7. Taï chimpanzees anticipate revisiting high-valued fruit trees from further distances.

    Science.gov (United States)

    Ban, Simone D; Boesch, Christophe; Janmaat, Karline R L

    2014-11-01

    The use of spatio-temporal memory has been argued to increase food-finding efficiency in rainforest primates. However, the exact content of this memory is poorly known to date. This study investigated what specific information from previous feeding visits chimpanzees (Pan troglodytes verus), in Taï National Park, Côte d'Ivoire, take into account when they revisit the same feeding trees. By following five adult females for many consecutive days, we tested from what distance the females directed their travels towards previously visited feeding trees and how previous feeding experiences and fruit tree properties influenced this distance. To exclude the influence of sensory cues, the females' approach distance was measured from their last significant change in travel direction until the moment they entered the tree's maximum detection field. We found that chimpanzees travelled longer distances to trees at which they had previously made food grunts and had rejected fewer fruits compared to other trees. In addition, the results suggest that the chimpanzees were able to anticipate the amount of fruit that they would find in the trees. Overall, our findings are consistent with the hypothesis that chimpanzees act upon a retrieved memory of their last feeding experiences long before they revisit feeding trees, which would indicate a daily use of long-term prospective memory. Further, the results are consistent with the possibility that positive emotional experiences help to trigger prospective memory retrieval in forest areas that are further away and have fewer cues associated with revisited feeding trees.

  8. High Pressure Scanning Tunneling Microscopy and High PressureX-ray Photoemission Spectroscopy Studies of Adsorbate Structure,Composition and Mobility during Catalytic Reactions on A Model SingleCrystal

    Energy Technology Data Exchange (ETDEWEB)

    Montano, Max O. [Univ. of California, Berkeley, CA (United States)

    2006-01-01

    Our research focuses on taking advantage of the ability of scanning tunneling microscopy (STM) to operate at high-temperatures and high-pressures while still providing real-time atomic resolution images. We also utilize high-pressure x-ray photoelectron spectroscopy (HPXPS) to monitor systems under identical conditions thus giving us chemical information to compare and contrast with the structural and dynamic data provided by STM.

  9. Dimers at Ge/Si(001) surfaces: Ge coverage dependent quenching, reactivation of flip-flop motion, and interaction with dimer vacancy lines

    International Nuclear Information System (INIS)

    Hirayama, H.; Mizuno, H.; Yoshida, R.

    2002-01-01

    We studied Ge coverage (θ Ge ) dependent quenching, reactivation of the flip-flop motion, and interaction with dimer vacancy lines (DVLs) of dimers on Ge/Si(001) surfaces using a scanning tunneling microscope (STM) combined with a molecular beam epitaxy apparatus. Deposition of ∼0.3 ML (monolayer) Ge quenched the flip-flop motion, making all dimers asymmetric. Further deposition introduced DVLs at θ Ge ≥∼0.5 ML, and symmetric dimer domains appeared again locally at θ≥1.5 ML. High-resolution STM images indicated that asymmetric dimer rows always invert their phase in alternation with buckled dimer's up-end at the DVLs. Low-temperature STM images indicated that the symmetric dimer domains were due to flip-flopping of asymmetric dimers activated by large θ Ge at room temperature. The symmetric dimer domains extended along the dimer rows over the DVLs due to the phase correlation

  10. A complex network approach for nanoparticle agglomeration analysis in nanoscale images

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Bruno Brandoli, E-mail: bruno.brandoli@ufms.br; Scabini, Leonardo Felipe, E-mail: leo.scabini@ufms.br; Margarido Orue, Jonatan Patrick, E-mail: jonatan.orue@ufms.br; Arruda, Mauro Santos de, E-mail: m.arruda@ufms.br; Goncalves, Diogo Nunes, E-mail: diogo.goncalves@ufms.br; Goncalves, Wesley Nunes, E-mail: wesley.goncalves@ufms.br [Federal University of Mato Grosso do Sul, CS Department (Brazil); Moreira, Raphaell, E-mail: moreira.raphaell@fu-berlin.de [Freie Universitat BerlinTakustr 3 (Germany); Rodrigues-Jr, Jose F, E-mail: junio@usp.br [University of Sao Paulo, CS Department (Brazil)

    2017-02-15

    Complex networks have been widely used in science and technology because of their ability to represent several systems. One of these systems is found in Biochemistry, in which the synthesis of new nanoparticles is a hot topic. However, the interpretation of experimental results in the search of new nanoparticles poses several challenges. This is due to the characteristics of nanoparticle images and due to their multiple intricate properties; one property of recurrent interest is the agglomeration of particles. Addressing this issue, this paper introduces an approach that uses complex networks to detect and describe nanoparticle agglomerates so to foster easier and more insightful analyses. In this approach, each detected particle in an image corresponds to a vertice and the distances between the particles define a criterion for creating edges. Edges are created if the distance is smaller than a radius of interest. Once this network is set, we calculate several discrete measures able to reveal the most outstanding agglomerates in a nanoparticle image. Experimental results using images of scanning tunneling microscopy (STM) of gold nanoparticles demonstrated the effectiveness of the proposed approach over several samples, as reflected by the separability between particles in three usual settings. The results also demonstrated efficacy for both convex and non-convex agglomerates.

  11. A combined optical, SEM and STM study of growth spirals on the polytypic cadmium iodide crystals

    Science.gov (United States)

    Singh, Rajendra; Samanta, S. B.; Narlikar, A. V.; Trigunayat, G. C.

    2000-05-01

    Some novel results of a combined sequential study of growth spirals on the basal surface of the richly polytypic CdI 2 crystals by optical microscopy, scanning electron microscopy (SEM) and scanning tunneling microscopy (STM) are presented and discussed. Under the high resolution and magnification achieved in the scanning electron microscope, the growth steps of large heights seen in the optical micrographs are found to have a large number of additional steps of smaller heights existing between any two adjacent large height growth steps. When further seen by a scanning tunneling microscope, which provides still higher resolution, sequences of unit substeps, each of height equal to the unit cell height of the underlying polytype, are revealed to exist on the surface. Several large steps also lie between the unit steps, with heights equal to an integral multiple of either the unit cell height of the underlying polytype or the thickness of a molecular sheet I-Cd-I. It is suggested that initially a giant screw dislocation may form by brittle fracture of the crystal platelet, which may gradually decompose into numerous unit dislocations during subsequent crystal growth.

  12. Supramolecular order and structural dynamics: A STM study of 2H-tetraphenylporphycene on Cu(111)

    Energy Technology Data Exchange (ETDEWEB)

    Stark, Michael; Träg, Johannes; Ditze, Stefanie; Steinrück, Hans-Peter; Marbach, Hubertus, E-mail: hubertus.marbach@fau.de [Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Interdisciplinary Center for Molecular Materials (ICMM), Universität Erlangen-Nürnberg, Henkestr. 42, 91054 Erlangen (Germany); Brenner, Wolfgang; Jux, Norbert [Lehrstuhl für Organische Chemie II, Universität Erlangen-Nürnberg, Henkestr. 42, 91054 Erlangen (Germany)

    2015-03-14

    The adsorption of 2H-tetraphenylporphycene (2HTPPc) on Cu(111) was investigated by scanning tunneling microscopy (STM). At medium coverages, supramolecular ordered islands are observed. The individual 2HTPPc molecules appear as two pairs of intense protrusions which are separated by an elongated depression. In the islands, the molecules are organized in rows oriented along one of the close packed Cu(111) substrate rows; the structure is stabilized by T-type interactions of the phenyl substituents of neighboring molecules. Two types of rows are observed, namely, highly ordered rows in which all molecules exhibit the same orientation, and less ordered rows in which the molecules exhibit two perpendicular orientations. Altogether, three different azimuthal orientations of 2HTPPc are observed within one domain, all of them rotated by 15° ± 1° relative to one closed packed Cu direction. The highly ordered rows are always separated by either one or two less ordered rows, with the latter structure being the thermodynamically more stable one. The situation in the islands is highly dynamic, such that molecules in the less ordered rows occasionally change orientation, also complete highly ordered rows can move. The supramolecular order and structural dynamics are discussed on the basis of the specific molecule-substrate and molecule-molecule interactions.

  13. High precision mass measurements in Ψ and Υ families revisited

    International Nuclear Information System (INIS)

    Artamonov, A.S.; Baru, S.E.; Blinov, A.E.

    2000-01-01

    High precision mass measurements in Ψ and Υ families performed in 1980-1984 at the VEPP-4 collider with OLYA and MD-1 detectors are revisited. The corrections for the new value of the electron mass are presented. The effect of the updated radiative corrections has been calculated for the J/Ψ(1S) and Ψ(2S) mass measurements [ru

  14. Final Technical Report for SISGR: Ultrafast Molecular Scale Chemical Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Hersam, Mark C. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Guest, Jeffrey R. [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Guisinger, Nathan P. [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Hla, Saw Wai [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Schatz, George C. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Seideman, Tamar [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Van Duyne, Richard P. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry

    2017-04-10

    The Northwestern-Argonne SISGR program utilized newly developed instrumentation and techniques including integrated ultra-high vacuum tip-enhanced Raman spectroscopy/scanning tunneling microscopy (UHV-TERS/STM) and surface-enhanced femtosecond stimulated Raman scattering (SE-FSRS) to advance the spatial and temporal resolution of chemical imaging for the study of photoinduced dynamics of molecules on plasmonically active surfaces. An accompanying theory program addressed modeling of charge transfer processes using constrained density functional theory (DFT) in addition to modeling of SE-FSRS, thereby providing a detailed description of the excited state dynamics. This interdisciplinary and highly collaborative research resulted in 62 publications with ~ 48% of them being co-authored by multiple SISGR team members. A summary of the scientific accomplishments from this SISGR program is provided in this final technical report.

  15. ARCHETYPES AND MYTHOLOGICAL MOTIFS: JOHN UPDIKE’S LEGACY REVISITED

    Directory of Open Access Journals (Sweden)

    Loreta Ulvydienė

    2018-04-01

    Full Text Available John Updike is widely considered to be one of the greatest, one of the most popular and sometimes most controversial writers concerned with the American small town and middle-class materialism. A lot of literary critics and researchers observe that Updike’s finest work came from his exploration of ordinary America and from his use of elegant prose, rich with metaphor, to portray the public and private feelings of Americans, their daily rounds of life. In addition, discussing Updike’s individual works a lot of literary critics and researchers have observed the writer’s attempts to re-write myth in “the mythical age”1 of the twentieth century. Naturally enough, as the return to myth is assumed to be a certain feature of the Modernist movement, half a century later since Updike’s famous novel Centaur was penned, it is indispensable to re-examine the writer’s fictional intentions in the usage of myth. More importantly, it is needful to determine whether we can see the mythic elements and realistic details as a continuum or as the contrasted opposites in his so called “historical chronicles”. Updike’s novels and stories are filled with mythological motifs and character archetypes. Thus, the study aims at revisiting John Updike’s creation considering mythological elements and archetypal images of his heroes alongside with heroic masculinity, war, terrorism and American perfectionism.

  16. A scanning Hall probe microscope for high resolution magnetic imaging down to 300 mK

    International Nuclear Information System (INIS)

    Khotkevych, V. V.; Bending, S. J.; Milosevic, M. V.

    2008-01-01

    We present the design, construction, and performance of a low-temperature scanning Hall probe microscope with submicron lateral resolution and a large scanning range. The detachable microscope head is mounted on the cold flange of a commercial 3 He-refrigerator (Oxford Instruments, Heliox VT-50) and operates between room temperature and 300 mK. It is fitted with a three-axis slip-stick nanopositioner that enables precise in situ adjustment of the probe location within a 6x6x7 mm 3 space. The local magnetic induction at the sample surface is mapped with an easily changeable microfabricated Hall probe [typically GsAs/AlGaAs or AlGaAs/InGaAs/GaAs Hall sensors with integrated scanning tunnel microscopy (STM) tunneling tips] and can achieve minimum detectable fields ≥10 mG/Hz 1/2 . The Hall probe is brought into very close proximity to the sample surface by sensing and controlling tunnel currents at the integrated STM tip. The instrument is capable of simultaneous tunneling and Hall signal acquisition in surface-tracking mode. We illustrate the potential of the system with images of superconducting vortices at the surface of a Nb thin film down to 372 mK, and also of labyrinth magnetic-domain patterns of an yttrium iron garnet film captured at room temperature.

  17. Atom-by-atom assembly

    International Nuclear Information System (INIS)

    Hla, Saw Wai

    2014-01-01

    Atomic manipulation using a scanning tunneling microscope (STM) tip enables the construction of quantum structures on an atom-by-atom basis, as well as the investigation of the electronic and dynamical properties of individual atoms on a one-atom-at-a-time basis. An STM is not only an instrument that is used to ‘see’ individual atoms by means of imaging, but is also a tool that is used to ‘touch’ and ‘take’ the atoms, or to ‘hear’ their movements. Therefore, the STM can be considered as the ‘eyes’, ‘hands’ and ‘ears’ of the scientists, connecting our macroscopic world to the exciting atomic world. In this article, various STM atom manipulation schemes and their example applications are described. The future directions of atomic level assembly on surfaces using scanning probe tips are also discussed. (review article)

  18. Excitation of propagating surface plasmons with a scanning tunnelling microscope.

    Science.gov (United States)

    Wang, T; Boer-Duchemin, E; Zhang, Y; Comtet, G; Dujardin, G

    2011-04-29

    Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10  µm. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.

  19. Excitation of propagating surface plasmons with a scanning tunnelling microscope

    International Nuclear Information System (INIS)

    Wang, T; Boer-Duchemin, E; Zhang, Y; Comtet, G; Dujardin, G

    2011-01-01

    Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10 μm. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.

  20. Excitation of propagating surface plasmons with a scanning tunnelling microscope

    Energy Technology Data Exchange (ETDEWEB)

    Wang, T; Boer-Duchemin, E; Zhang, Y; Comtet, G; Dujardin, G, E-mail: Elizabeth.Boer-Duchemin@u-psud.fr [Institut des Sciences Moleculaire d' Orsay (ISMO), CNRS Universite Paris-Sud, 91405 Orsay (France)

    2011-04-29

    Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10 {mu}m. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.

  1. Commentary on "Distributed Revisiting: An Analytic for Retention of Coherent Science Learning"

    Science.gov (United States)

    Hewitt, Jim

    2015-01-01

    The article, "Distributed Revisiting: An Analytic for Retention of Coherent Science Learning" is an interesting study that operates at the intersection of learning theory and learning analytics. The authors observe that the relationship between learning theory and research in the learning analytics field is constrained by several…

  2. Double digest revisited : Complexity and Approximability in the Presence of Noisy Data

    NARCIS (Netherlands)

    Cieliebak, Mark; Eidenbenz, Stephan; Woeginger, Gerhard; Warnow, Tandy; Zhu, Binhai

    2003-01-01

    We revisit the Double Digest problem, which occurs in sequencing of large DNA strings and consists of reconstructing the relative positions of cut sites from two different enzymes: we first show that Double Digest is strongly NP-complete, improving upon previous results that only showed weak

  3. Scanning tunneling microscopic images and scanning tunneling spectra for coupled rectangular quantum corrals

    International Nuclear Information System (INIS)

    Mitsuoka, Shigenori; Tamura, Akira

    2011-01-01

    Assuming that an electron confined by double δ-function barriers lies in a quasi-stationary state, we derived eigenstates and eigenenergies of the electron. Such an electron has a complex eigenenergy, and the imaginary part naturally leads to the lifetime of the electron associated with tunneling through barriers. We applied this point of view to the electron confined in a rectangular quantum corral (QC) on a noble metal surface, and obtained scanning tunneling microscopic images and a scanning tunneling spectrum consistent with experimental ones. We investigated the electron states confined in coupled QCs and obtained the coupled states constructed with bonding and anti-bonding states. Using those energy levels and wavefunctions we specified scanning tunneling microscope (STM) images and scanning tunneling spectra (STS) for the doubly and triply coupled QCs. In addition we pointed out the feature of resonant electron states associated with the same QCs at both ends of the triply coupled QCs.

  4. First-principles lattice-gas Hamiltonian revisited: O-Pd(100)

    OpenAIRE

    Kappus, Wolfgang

    2016-01-01

    The methodology of deriving an adatom lattice-gas Hamiltonian (LGH) from first principles (FP) calculations is revisited. Such LGH cluster expansions compute a large set of lateral pair-, trio-, quarto interactions by solving a set of linear equations modelling regular adatom configurations and their FP energies. The basic assumption of truncating interaction terms beyond fifth nearest neighbors does not hold when adatoms show longer range interactions, e.g. substrate mediated elastic interac...

  5. SENTINEL-2 GLOBAL REFERENCE IMAGE VALIDATION AND APPLICATION TO MULTITEMPORAL PERFORMANCES AND HIGH LATITUDE DIGITAL SURFACE MODEL

    Directory of Open Access Journals (Sweden)

    A. Gaudel

    2017-05-01

    Full Text Available In the frame of the Copernicus program of the European Commission, Sentinel-2 is a constellation of 2 satellites with a revisit time of 5 days in order to have temporal images stacks and a global coverage over terrestrial surfaces. Satellite 2A was launched in June 2015, and satellite 2B will be launched in March 2017. In cooperation with the European Space Agency (ESA, the French space agency (CNES is in charge of the image quality of the project, and so ensures the CAL/VAL commissioning phase during the months following the launch. This cooperation is also extended to routine phase as CNES supports European Space Research Institute (ESRIN and the Sentinel-2 Mission performance Centre (MPC for validation in geometric and radiometric image quality aspects, and in Sentinel-2 GRI geolocation performance assessment whose results will be presented in this paper. The GRI is a set of S2A images at 10m resolution covering the whole world with a good and consistent geolocation. This ground reference enables accurate multi-temporal registration of refined Sentinel-2 products. While not primarily intended for the generation of DSM, Sentinel-2 swaths overlap between orbits would also allow for the generation of a complete DSM of land and ices over 60° of northern latitudes (expected accuracy: few S2 pixels in altimetry. This DSM would benefit from the very frequent revisit times of Sentinel-2, to monitor ice or snow level in area of frequent changes, or to increase measurement accuracy in areas of little changes.

  6. SENTINEL-2 Global Reference Image Validation and Application to Multitemporal Performances and High Latitude Digital Surface Model

    Science.gov (United States)

    Gaudel, A.; Languille, F.; Delvit, J. M.; Michel, J.; Cournet, M.; Poulain, V.; Youssefi, D.

    2017-05-01

    In the frame of the Copernicus program of the European Commission, Sentinel-2 is a constellation of 2 satellites with a revisit time of 5 days in order to have temporal images stacks and a global coverage over terrestrial surfaces. Satellite 2A was launched in June 2015, and satellite 2B will be launched in March 2017. In cooperation with the European Space Agency (ESA), the French space agency (CNES) is in charge of the image quality of the project, and so ensures the CAL/VAL commissioning phase during the months following the launch. This cooperation is also extended to routine phase as CNES supports European Space Research Institute (ESRIN) and the Sentinel-2 Mission performance Centre (MPC) for validation in geometric and radiometric image quality aspects, and in Sentinel-2 GRI geolocation performance assessment whose results will be presented in this paper. The GRI is a set of S2A images at 10m resolution covering the whole world with a good and consistent geolocation. This ground reference enables accurate multi-temporal registration of refined Sentinel-2 products. While not primarily intended for the generation of DSM, Sentinel-2 swaths overlap between orbits would also allow for the generation of a complete DSM of land and ices over 60° of northern latitudes (expected accuracy: few S2 pixels in altimetry). This DSM would benefit from the very frequent revisit times of Sentinel-2, to monitor ice or snow level in area of frequent changes, or to increase measurement accuracy in areas of little changes.

  7. Advanced Change Theory Revisited: An Article Critique

    Directory of Open Access Journals (Sweden)

    R. Scott Pochron

    2008-12-01

    Full Text Available The complexity of life in 21st century society requires new models for leading and managing change. With that in mind, this paper revisits the model for Advanced Change Theory (ACT as presented by Quinn, Spreitzer, and Brown in their article, “Changing Others Through Changing Ourselves: The Transformation of Human Systems” (2000. The authors present ACT as a potential model for facilitating change in complex organizations. This paper presents a critique of the article and summarizes opportunities for further exploring the model in the light of current trends in developmental and integral theory.

  8. Revisiting fifth forces in the Galileon model

    Energy Technology Data Exchange (ETDEWEB)

    Burrage, Clare [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Gruppe Theorie; Seery, David [Sussex Univ., Brighton (United Kingdom). Dept. of Physics and Astronomy

    2010-05-15

    A Galileon field is one which obeys a spacetime generalization of the non- relativistic Galilean invariance. Such a field may possess non-canonical kinetic terms, but ghost-free theories with a well-defined Cauchy problem exist, constructed using a finite number of relevant operators. The interactions of this scalar with matter are hidden by the Vainshtein effect, causing the Galileon to become weakly coupled near heavy sources. We revisit estimates of the fifth force mediated by a Galileon field, and show that the parameters of the model are less constrained by experiment than previously supposed. (orig.)

  9. Large J expansion in ABJM theory revisited.

    Science.gov (United States)

    Dimov, H; Mladenov, S; Rashkov, R C

    Recently there has been progress in the computation of the anomalous dimensions of gauge theory operators at strong coupling by making use of the AdS/CFT correspondence. On the string theory side they are given by dispersion relations in the semiclassical regime. We revisit the problem of a large-charge expansion of the dispersion relations for simple semiclassical strings in an [Formula: see text] background. We present the calculation of the corresponding anomalous dimensions of the gauge theory operators to an arbitrary order using three different methods. Although the results of the three methods look different, power series expansions show their consistency.

  10. The power reinforcement framework revisited

    DEFF Research Database (Denmark)

    Nielsen, Jeppe; Andersen, Kim Normann; Danziger, James N.

    2016-01-01

    Whereas digital technologies are often depicted as being capable of disrupting long-standing power structures and facilitating new governance mechanisms, the power reinforcement framework suggests that information and communications technologies tend to strengthen existing power arrangements within...... public organizations. This article revisits the 30-yearold power reinforcement framework by means of an empirical analysis on the use of mobile technology in a large-scale programme in Danish public sector home care. It explores whether and to what extent administrative management has controlled decision......-making and gained most benefits from mobile technology use, relative to the effects of the technology on the street-level workers who deliver services. Current mobile technology-in-use might be less likely to be power reinforcing because it is far more decentralized and individualized than the mainly expert...

  11. Partially overlapping sensorimotor networks underlie speech praxis and verbal short-term memory: evidence from apraxia of speech following acute stroke.

    Science.gov (United States)

    Hickok, Gregory; Rogalsky, Corianne; Chen, Rong; Herskovits, Edward H; Townsley, Sarah; Hillis, Argye E

    2014-01-01

    We tested the hypothesis that motor planning and programming of speech articulation and verbal short-term memory (vSTM) depend on partially overlapping networks of neural regions. We evaluated this proposal by testing 76 individuals with acute ischemic stroke for impairment in motor planning of speech articulation (apraxia of speech, AOS) and vSTM in the first day of stroke, before the opportunity for recovery or reorganization of structure-function relationships. We also evaluated areas of both infarct and low blood flow that might have contributed to AOS or impaired vSTM in each person. We found that AOS was associated with tissue dysfunction in motor-related areas (posterior primary motor cortex, pars opercularis; premotor cortex, insula) and sensory-related areas (primary somatosensory cortex, secondary somatosensory cortex, parietal operculum/auditory cortex); while impaired vSTM was associated with primarily motor-related areas (pars opercularis and pars triangularis, premotor cortex, and primary motor cortex). These results are consistent with the hypothesis, also supported by functional imaging data, that both speech praxis and vSTM rely on partially overlapping networks of brain regions.

  12. Improved design for a low temperature scanning tunneling microscope with an in situ tip treatment stage.

    Science.gov (United States)

    Kim, J-J; Joo, S H; Lee, K S; Yoo, J H; Park, M S; Kwak, J S; Lee, Jinho

    2017-04-01

    The Low Temperature Scanning Tunneling Microscope (LT-STM) is an extremely valuable tool not only in surface science but also in condensed matter physics. For years, numerous new ideas have been adopted to perfect LT-STM performances-Ultra-Low Vibration (ULV) laboratory and the rigid STM head design are among them. Here, we present three improvements for the design of the ULV laboratory and the LT-STM: tip treatment stage, sample cleaving stage, and vibration isolation system. The improved tip treatment stage enables us to perform field emission for the purpose of tip treatment in situ without exchanging samples, while our enhanced sample cleaving stage allows us to cleave samples at low temperature in a vacuum without optical access by a simple pressing motion. Our newly designed vibration isolation system provides efficient space usage while maintaining vibration isolation capability. These improvements enhance the quality of spectroscopic imaging experiments that can last for many days and provide increased data yield, which we expect can be indispensable elements in future LT-STM designs.

  13. Use of Local Electrochemical Methods (SECM, EC-STM) and AFM to Differentiate Microstructural Effects (EBSD) on Very Pure Copper

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Lombardia, Esther; Graeve, Iris De; Terryn, Herman [Vrije Universiteit Brussel, Brussels (Belgium); Lapeire, Linsey; Verbeken, Kim; Kestens, Leo [Ghent University, Zwijnaarde (Ghent) (Belgium); Maurice, Vincent; Klein, Lorena; Marcus, Philippe [Institut de Recherche de Chimie Paris, Paris (France); Gonzalez-Garcia, Yaiza; Mol, Arjan [Delft University of Technology, Delft (Netherlands)

    2017-02-15

    When aiming for an increased and more sustainable use of metals a thorough knowledge of the corrosion phenomenon as function of the local metal microstructure is of crucial importance. In this work, we summarize the information presented in our previous publications and present an overview of the different local (electrochemical) techniques that have been proven to be effective in studying the relation between different microstructural variables and their different electrochemical behavior. Atomic force microscopy (AFM), scanning electrochemical microscopy (SECM), and electrochemical scanning tunneling microscopy (EC-STM) were used in combination with electron backscatter diffraction (EBSD). Consequently, correlations could be identified between the grain orientation and grain boundary characteristics, on the one hand, and the electrochemical behavior on the other hand. The grain orientation itself has an influence on the corrosion, and the orientation of the neighboring grains also seems to play a decisive role in the dissolution rate. With respect to intergranular corrosion, only coherent twin boundaries seem to be resistant.

  14. Meeting Earth Observation Requirements for Global Agricultural Monitoring: An Evaluation of the Revisit Capabilities of Current and Planned Moderate Resolution Optical Earth Observing Missions

    Directory of Open Access Journals (Sweden)

    Alyssa K. Whitcraft

    2015-01-01

    Full Text Available Agriculture is a highly dynamic process in space and time, with many applications requiring data with both a relatively high temporal resolution (at least every 8 days and fine-to-moderate (FTM < 100 m spatial resolution. The relatively infrequent revisit of FTM optical satellite observatories coupled with the impacts of cloud occultation have translated into a barrier for the derivation of agricultural information at the regional-to-global scale. Drawing upon the Group on Earth Observations Global Agricultural Monitoring (GEOGLAM Initiative’s general satellite Earth observation (EO requirements for monitoring of major production areas, Whitcraft et al. (this issue have described where, when, and how frequently satellite data acquisitions are required throughout the agricultural growing season at 0.05°, globally. The majority of areas and times of year require multiple revisits to probabilistically yield a view at least 70%, 80%, 90%, or 95% clear within eight days, something that no present single FTM optical observatory is capable of delivering. As such, there is a great potential to meet these moderate spatial resolution optical data requirements through a multi-space agency/multi-mission constellation approach. This research models the combined revisit capabilities of seven hypothetical constellations made from five satellite sensors—Landsat 7 Enhanced Thematic Mapper (Landsat 7 ETM+, Landsat 8 Operational Land Imager and Thermal Infrared Sensor (Landsat 8 OLI/TIRS, Resourcesat-2 Advanced Wide Field Sensor (Resourcesat-2 AWiFS, Sentinel-2A Multi-Spectral Instrument (MSI, and Sentinel-2B MSI—and compares these capabilities with the revisit frequency requirements for a reasonably cloud-free clear view within eight days throughout the agricultural growing season. Supplementing Landsat 7 and 8 with missions from different space agencies leads to an improved capacity to meet requirements, with Resourcesat-2 providing the largest

  15. Revisit boundary conditions for the self-adjoint angular flux formulation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yaqi [Idaho National Lab. (INL), Idaho Falls, ID (United States); Gleicher, Frederick N. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-01

    We revisit the boundary conditions for SAAF. We derived the equivalent parity variational form ready for coding up. The more rigorous approach of evaluating odd parity should be solving the odd parity equation coupled with the even parity. We proposed a symmetric reflecting boundary condition although neither positive definiteness nor even-odd decoupling is achieved. A simple numerical test verifies the validity of these boundary conditions.

  16. Place attachment and social legitimacy: Revisiting the sustainable entrepreneurship journey

    OpenAIRE

    Kibler, E; Fink, M; Lang, R; Munoz, PA

    2015-01-01

    This paper revisits the sustainable entrepreneurship journey by introducing a ‘place- based’ sustainable venture path model. We suggest that distinguishing between emo- tional (‘caring about the place’) and instrumental (‘using the place’) place attachment of sustainable entrepreneurs deepens our understanding of how place-based challenges of sustainable venture legitimacy are managed over time. We conclude with avenues for future sustainable entrepreneurship research.

  17. High Pressure Scanning Tunneling Microscopy Studies of AdsorbateStructure and Mobility during Catalytic Reactions: Novel Design of anUltra High Pressure, High Temperature Scanning Tunneling MicroscopeSystem for Probing Catalytic Conversions

    Energy Technology Data Exchange (ETDEWEB)

    Tang, David Chi-Wai [Univ. of California, Berkeley, CA (United States)

    2005-05-16

    The aim of the work presented therein is to take advantage of scanning tunneling microscope’s (STM) capability for operation under a variety of environments under real time and at atomic resolution to monitor adsorbate structures and mobility under high pressures, as well as to design a new generation of STM systems that allow imaging in situ at both higher pressures (35 atm) and temperatures (350 °C).

  18. Teacher Communication Concerns Revisited: Calling into Question the Gnawing Pull towards Equilibrium

    Science.gov (United States)

    Dannels, Deanna P.

    2015-01-01

    This study revisits the long-standing teacher communication concerns framework originating over three decades ago. Analysis of 10 years of contemporary GTA teacher communication concerns reveals a typology of 10 concerns, which taken together construct teaching as a process of negotiating relationships, managing identities, and focusing attention.…

  19. Revisiting Learning in Higher Education--Framing Notions Redefined through an Ecological Perspective

    Science.gov (United States)

    Damsa, Crina; Jornet, Alfredo

    2016-01-01

    This article employs an ecological perspective as a means of revisiting the notion of learning, with a particular focus on learning in higher education. Learning is reconceptualised as a process entailing mutually constitutive, epistemic, social and affective relations in which knowledge, identity and agency become collective achievements of whole…

  20. Lorentz violation naturalness revisited

    Energy Technology Data Exchange (ETDEWEB)

    Belenchia, Alessio; Gambassi, Andrea; Liberati, Stefano [SISSA - International School for Advanced Studies, via Bonomea 265, 34136 Trieste (Italy); INFN, Sezione di Trieste, via Valerio 2, 34127 Trieste (Italy)

    2016-06-08

    We revisit here the naturalness problem of Lorentz invariance violations on a simple toy model of a scalar field coupled to a fermion field via a Yukawa interaction. We first review some well-known results concerning the low-energy percolation of Lorentz violation from high energies, presenting some details of the analysis not explicitly discussed in the literature and discussing some previously unnoticed subtleties. We then show how a separation between the scale of validity of the effective field theory and that one of Lorentz invariance violations can hinder this low-energy percolation. While such protection mechanism was previously considered in the literature, we provide here a simple illustration of how it works and of its general features. Finally, we consider a case in which dissipation is present, showing that the dissipative behaviour does not percolate generically to lower mass dimension operators albeit dispersion does. Moreover, we show that a scale separation can protect from unsuppressed low-energy percolation also in this case.

  1. Atomic-Scale Characterization and Manipulation of Freestanding Graphene Using Adapted Capabilities of a Scanning Tunneling Microscope

    Science.gov (United States)

    Barber, Steven

    Graphene was the first two-dimensional material ever discovered, and it exhibits many unusual phenomena important to both pure and applied physics. To ensure the purest electronic structure, or to study graphene's elastic properties, it is often suspended over holes or trenches in a substrate. The aim of the research presented in this dissertation was to develop methods for characterizing and manipulating freestanding graphene on the atomic scale using a scanning tunneling microscope (STM). Conventional microscopy and spectroscopy techniques must be carefully reconsidered to account for movement of the extremely flexible sample. First, the acquisition of atomic-scale images of freestanding graphene using the STM and the ability to pull the graphene perpendicular to its plane by applying an electrostatic force with the STM tip are demonstrated. The atomic-scale images contained surprisingly large corrugations due to the electrostatic attractive force varying in registry with the local density of states. Meanwhile, a large range of control over the graphene height at a point was obtained by varying the tip bias voltage, and the application to strain engineering of graphene's so-called pseudomagnetic field is examined. Next, the effect of the tunneling current was investigated. With increasing current, the graphene sample moves away from the tip rather than toward it. It was determined that this must be due to local heating by the electric current, causing the graphene to contract because it has a negative coefficient of thermal expansion. Finally, by imaging a very small area, the STM can monitor the height of one location over long time intervals. Results sometimes exhibit periodic behavior, with a frequency and amplitude that depend on the tunneling current. These fluctuations are interpreted as low-frequency flexural phonon modes within elasticity theory. All of these findings set the foundation for employing a STM in the study of freestanding graphene.

  2. Tetrairon(III) Single Molecule Magnet Studied by Scanning Tunneling Microscopy and Spectroscopy

    Science.gov (United States)

    Oh, Youngtek; Jeong, Hogyun; Lee, Minjun; Kwon, Jeonghoon; Yu, Jaejun; Mamun, Shariful Islam; Gupta, Gajendra; Kim, Jinkwon; Kuk, Young

    2011-03-01

    Tetrairon(III) single-molecule magnet (SMM) on a clean Au(111) has studied using scanning tunneling microscopy (STM) and spectroscopy (STS) to understand quantum mechanical tunneling of magnetization and hysteresis of pure molecular origin. Before the STM studies, elemental analysis, proton nuclear magnetic resonance (NMR) measurement and Energy Dispersive X- ray Spectroscopy (EDS) were carried out to check the robustness of the sample. The STM image of this molecule shows a hexagonal shape, with a phenyl ring at the center and surrounding six dipivaloylmethane ligands. Two peaks are observed at 0.5 eV, 1.5 eV in the STS results, agreeing well with the first principles calculations. Spin-polarized scanning tunneling microscopy (SPSTM) measurements have been performed with a magnetic tip to get the magnetization image of the SMM. We could observe the antiferromagnetic coupling and a centered- triangular topology with six alkoxo bridges inside the molecule while applying external magnetic fields.

  3. Intermediate Nucleation State of GaN Growth

    Science.gov (United States)

    Zheng, L. X.; Xie, M. H.; Tong, S. Y.

    2001-03-01

    Homoexpitaxial nucleation of GaN during molecular-beam epitaxy is followed by scanning tunneling microcopy (STM). We observe a metastable nucleation state, which manifests as “ghost” islands in STM images. These “ghost” islands can be irreversibly driven into normal islands by continuous STM imaging. It is further established that the “ghost” island formation is related to the presence of excess Ga atoms on the surface: Normal islands are only seen under the N-rich or stoichiometric flux condition, whereas “ghost” islands are observed under Ga-rich conditions. For intermediate excess-Ga coverages, both normal and “ghost” islands are present, however, they show distinctly different sizes, suggesting different nucleation states for the two. A growth model is proposed to account for the formation of metastable, “ghost” islands. Kinetic Monte Carlo simulation is carried out and main features of the surface are reproduced. We acknowledge financial support from HK RGC under grant Nos. 7396/00P, 7142/99P, and 7121/00P.

  4. {sup 18}F-FDOPA PET/CT imaging of insulinoma revisited

    Energy Technology Data Exchange (ETDEWEB)

    Imperiale, Alessio; Namer, Izzie-Jacques [University Hospitals of Strasbourg, Department of Biophysics and Nuclear Medicine, Strasbourg (France); University of Strasbourg/CNRS and FMTS, Faculty of Medicine, ICube - UMR 7357, Strasbourg (France); Sebag, Frederic [Aix-Marseille University, Department of Endocrine Surgery, La Timone University Hospital, Marseille (France); Vix, Michel [University of Strasbourg, Department of General, Digestive, and Endocrine Surgery, IRCAD-IHU, Strasbourg (France); Castinetti, Frederic [Aix-Marseille University, Department of Endocrinology, Diabetes and Metabolic Disorders, La Timone University Hospital, Marseille (France); Kessler, Laurence; Moreau, Francois [University of Strasbourg, Department of Diabetology, University Hospital of Strasbourg, Strasbourg (France); Bachellier, Philippe [University Hospitals of Strasbourg, Department of Visceral Surgery and Transplantation, Strasbourg (France); Guillet, Benjamin; Mundler, Olivier [Aix-Marseille University, Department of Nuclear Medicine, La Timone University Hospital, CERIMED, Marseille (France); Taieb, David [Aix-Marseille University, Department of Nuclear Medicine, La Timone University Hospital, CERIMED, Marseille (France); Aix-Marseille University, Biophysics and Nuclear Medecine, La Timone University Hospital, European Center for Research in Medical Imaging, Marseille (France)

    2014-11-01

    {sup 18}F-FDOPA PET imaging is increasingly used in the work-up of patients with neuroendocrine tumours. It has been shown to be of limited value in localizing pancreatic insulin-secreting tumours in adults with hyperinsulinaemic hypoglycaemia (HH) mainly due to {sup 18}F-FDOPA uptake by the whole pancreatic gland. The objective of this study was to review our experience with {sup 18}F-FDOPA PET/CT imaging with carbidopa (CD) premedication in patients with HH in comparison with PET/CT studies performed without CD premedication in an independent population. A retrospective study including 16 HH patients who were investigated between January 2011 and December 2013 using {sup 18}F-FDOPA PET/CT (17 examinations) in two academic endocrine tumour centres was conducted. All PET/CT examinations were performed under CD premedication (200 mg orally, 1 - 2 h prior to tracer injection). The PET/CT acquisition protocol included an early acquisition (5 min after {sup 18}F-FDOPA injection) centred over the upper abdomen and a delayed whole-body acquisition starting 20 - 30 min later. An independent series of eight consecutive patients with HH and investigated before 2011 were considered for comparison. All patients had a reference whole-body PET/CT scan performed about 1 h after {sup 18}F-FDOPA injection. In all cases, PET/CT was performed without CD premedication. In the study group, {sup 18}F-FDOPA PET/CT with CD premedication was positive in 8 out of 11 patients with histologically proven insulinoma (73 %). All {sup 18}F-FDOPA PET/CT-avid insulinomas were detected on early images and 5 of 11 (45 %) on delayed ones. The tumour/normal pancreas uptake ratio was not significantly different between early and delayed acquisitions. Considering all patients with HH, including those without imaging evidence of disease, the detection rate of the primary lesions using CD-assisted {sup 18}F-FDOPA PET/CT was 53 %, showing 9 insulinomas in 17 studies performed. In the control group (without

  5. Quark matter revisited with non-extensive MIT bag model

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Pedro H.G.; Nunes da Silva, Tiago; Menezes, Debora P. [Universidade Federal de Santa Catarina, Departamento de Fisica, CFM, Florianopolis (Brazil); Deppman, Airton [Instituto de Fisica da Universidade de Sao Paulo, Sao Paulo (Brazil)

    2017-10-15

    In this work we revisit the MIT bag model to describe quark matter within both the usual Fermi-Dirac and the Tsallis statistics. We verify the effects of the non-additivity of the latter by analysing two different pictures: the first order phase transition of the QCD phase diagram and stellar matter properties. While the QCD phase diagram is visually affected by the Tsallis statistics, the resulting effects on quark star macroscopic properties are barely noticed. (orig.)

  6. Nanoscale coupling of photons to vibrational excitation of Ag nanoparticle 2D array studied by scanning tunneling microscope light emission spectroscopy.

    Science.gov (United States)

    Katano, Satoshi; Toma, Koji; Toma, Mana; Tamada, Kaoru; Uehara, Yoichi

    2010-11-28

    Scanning tunneling microscope light emission (STM-LE) spectroscopy has been utilized to elucidate the luminescence phenomena of Ag nanoparticles capped with myristate (myristate-capped AgNP) and 2-methyl-1-propanethiolate (C(4)S-capped AgNP) on the dodecanethiol-precovered Au substrate. The STM imaging revealed that myristate-capped AgNPs form an ordered hexagonal array whereas C(4)S-capped AgNPs show imperfect ordering, indicating that a shorter alkyl chain of C(4)S-capped AgNP is not sufficient to form rigid interdigitation. It should be noted that such a nanoparticle ordering affects the luminescence properties of the Ag nanoparticle. We found that the STM-LE is only detected from the Ag nanoparticles forming the two-dimensional superlattice. This indicates that the STM-LE of the Ag nanoparticle is radiated via the collective excitation of the local surface plasmon resonance (LSPR) spread over the Ag nanoparticles. Note that the STM-LE spectra of the Ag nanoparticles exhibit spike-like peaks superimposed on the broad light emission peak. Using Raman spectroscopy, we concluded that the spike-like structure appearing in the STM-LE spectra is associated with the vibrational excitation of the molecule embedded between Ag nanoparticles.

  7. My First CMC Article Revisited: A Window on Spanish L2 Interlanguage

    Science.gov (United States)

    Blake, Robert

    2016-01-01

    The computer-assisted language learning (CALL) field seems to change overnight with new technological affordances. Blake revisits his 2000 "LLT" article on computer-mediation communication (CMC) in order to reflect on how the field has examined this topic over the past decade or so. While the Interaction Hypothesis continues to guide…

  8. Risk prediction of emergency department revisit 30 days post discharge: a prospective study.

    Directory of Open Access Journals (Sweden)

    Shiying Hao

    Full Text Available Among patients who are discharged from the Emergency Department (ED, about 3% return within 30 days. Revisits can be related to the nature of the disease, medical errors, and/or inadequate diagnoses and treatment during their initial ED visit. Identification of high-risk patient population can help device new strategies for improved ED care with reduced ED utilization.A decision tree based model with discriminant Electronic Medical Record (EMR features was developed and validated, estimating patient ED 30 day revisit risk. A retrospective cohort of 293,461 ED encounters from HealthInfoNet (HIN, Maine's Health Information Exchange (HIE, between January 1, 2012 and December 31, 2012, was assembled with the associated patients' demographic information and one-year clinical histories before the discharge date as the inputs. To validate, a prospective cohort of 193,886 encounters between January 1, 2013 and June 30, 2013 was constructed. The c-statistics for the retrospective and prospective predictions were 0.710 and 0.704 respectively. Clinical resource utilization, including ED use, was analyzed as a function of the ED risk score. Cluster analysis of high-risk patients identified discrete sub-populations with distinctive demographic, clinical and resource utilization patterns.Our ED 30-day revisit model was prospectively validated on the Maine State HIN secure statewide data system. Future integration of our ED predictive analytics into the ED care work flow may lead to increased opportunities for targeted care intervention to reduce ED resource burden and overall healthcare expense, and improve outcomes.

  9. Investigation into scanning tunnelling luminescence microscopy

    International Nuclear Information System (INIS)

    Manson-Smith, S.K.

    2001-01-01

    This work reports on the development of a scanning tunnelling luminescence (STL) microscope and its application to the study of Ill-nitride semiconductor materials used in the production of light emitting devices. STL microscopy is a technique which uses the high resolution topographic imaging capabilities of the scanning tunnelling microscope (STM) to generate high resolution luminescence images. The STM tunnelling current acts as a highly localised source of electrons (or holes) which generates luminescence in certain materials. Light generated at the STM tunnelling junction is collected concurrently with the height variation of the tunnelling probe as it is scanned across a sample surface, producing simultaneous topographic and luminescence images. Due to the very localised excitation source, high resolution luminescence images can be obtained. Spectroscopic resolution can be obtained by using filters. Additionally, the variation of luminescence intensity with tunnel current and with bias voltage can provide information on recombination processes and material properties. The design and construction of a scanning tunnelling luminescence microscope is described in detail. Operating under ambient conditions, the microscope has several novel features, including a new type of miniature inertial slider-based approach motor, large solid-angle light collection optical arrangement and a tip-height regulation system which requires the minimum of operator input. (author)

  10. A study of surface diffusion with the scanning tunneling microscope from fluctuations of the tunneling current

    Energy Technology Data Exchange (ETDEWEB)

    Manuel, Lozano [Iowa State Univ., Ames, IA (United States)

    1996-01-12

    The transport of atoms or molecules over surfaces has been an important area of study for several decades now, with its progress generally limited by the available experimental techniques to characterize the phenomena. A number of methods have been developed over the years to measure surface diffusion yet only very few systems have been characterized to this day mainly due to the physical limitations inherent in these available methods. Even the STM with its astonishing atomically-resolved images of the surface has been limited in terms of its capability to determine mass transport properties. This is because the STM is inherently a ``slow`` instrument, i.e., a finite time is needed for signal averaging in order to produce the image. A need exists for additional surface diffusion measurement techniques, ideally ones which are able to study varied systems and measure a wide range of diffusion rates. The STM (especially because of its highly local nature) presents itself as a promising tool to conduct dynamical studies if its poor time resolution during ``normal operation`` can somehow be overcome. The purpose of this dissertation is to introduce a new technique of using the STM to measure adatom mobility on surfaces -- one with a capacity to achieve excellent time resolution.

  11. Application fo tunneling and atomic force detection to machines and scientific instruments. Tunnel gensho ya genshikan no mechatronics eno oyo

    Energy Technology Data Exchange (ETDEWEB)

    Kawakatsu, H. (The University of Tokyo, Tokyo (Japan). Institute of Industrial Science)

    1991-11-01

    It is now about ten years since the scanning tunnel microscope (STM) and the atomic force microscope (AFM) were invented. These microscopes are used very importantly today as a surface analyzer capable of atomic order analysis for their very high resolution. The STM and AFM obtain images of atomic orders by means of mechanical scanning of the probes. This means that the microscopes can control positioning, force detection and displacement in regions of sub-nanometer orders. Examples of researches may include detection of acceleration, length measurement, positioning, force detection, nano-tripology, processing and gravitational wave detection. As described above, this paper notes the researches derived from the operational principles of the STM and AFM, rather than the researches on the observation objects. The great diversity of the researches taken up and the greatness in the number of researches in the STM and AFM gather how superbly germinative these were. 34 refs.

  12. Local stabilization of single-walled carbon nanotubes on Si(100)-2 x 1:H via nanoscale hydrogen desorption with an ultrahigh vacuum scanning tunnelling microscope

    International Nuclear Information System (INIS)

    Albrecht, Peter M; Lyding, Joseph W

    2007-01-01

    An ultrahigh vacuum scanning tunnelling microscope (UHV-STM) was used to modify the interface between isolated ∼10 A-diameter single-walled carbon nanotubes (SWNTs) and the hydrogen-passivated Si(100) surface. Room-temperature UHV-STM desorption of hydrogen at the SWNT/H-Si(100) interface resulted in the local mechanical stabilization of tubes originally perturbed by the rastered STM tip under nominal imaging conditions. For the section of the SWNT contacted by depassivated Si, a topographic depression of 1.5 A (1 A) was measured in the case of parallel (nearly perpendicular) alignment between the tube axis and the Si dimer rows, in agreement with existing first-principles calculations. The compatibility of hydrogen-resist UHV-STM nanolithography with SWNTs adsorbed on H-Si(100) would enable the atomically precise placement of single molecules in proximity to the tube for the bottom-up fabrication of molecular electronic devices

  13. The Best and the Rest: Revisiting the Norm of Normality of Individual Performance

    Science.gov (United States)

    O'Boyle, Ernest, Jr.; Aguinis, Herman

    2012-01-01

    We revisit a long-held assumption in human resource management, organizational behavior, and industrial and organizational psychology that individual performance follows a Gaussian (normal) distribution. We conducted 5 studies involving 198 samples including 633,263 researchers, entertainers, politicians, and amateur and professional athletes.…

  14. Atom probe, AFM and STM study on vacuum fired stainless steel

    International Nuclear Information System (INIS)

    Stupnik, A.; Frank, P.; Leisch, M.

    2008-01-01

    Full text: Stainless steel is one of the most commonly used structural materials for vacuum equipment. An efficient method to reduce the outgassing rate from stainless steel is a high temperature bakeout in vacuum (vacuum firing). This procedure reduces significantly the amount of dissolved hydrogen in the bulk. For the outgassing process the recombination rate of hydrogen atoms to the molecules plays the determining role and recombination is strongly related to the surface structure and composition. To get more detailed information about the surface morphology and composition AFM, STM and atom probe studies were carried out. Experiments on AISI 304L stainless steel samples show that the surface reconstructs completely during vacuum firing and large atomically flat terraces bounded by bunched steps and facets are formed. The large flat terraces can be assigned to (111) planes. The bunched steps and facets are corresponding in orientation almost to (110) planes and (100) planes. Surface inspection after vacuum firing by Auger electron spectroscopy (AES) gives reason for a composition change indicated by a reduction of the chromium signal in relation to the iron and nickel signal. Since the information depth of AES covers several atomic layers not only the top atomic layer of the sample surface is probed. For this reason 3D atom probe was used as well suited tool to investigate the segregation behavior of this alloy with the goal to examine the change in local chemical composition due to the high temperature treatment. As a result of vacuum firing the atom probe experiments show a significant enrichment of nickel at the top surface layer. In the second atomic layer chromium enrichment is detected. After vacuum firing the average composition below the second atomic layer shows certain chromium depletion up to 2 nm in depth. The observed changes in surface chemistry influence recombination and desorption probability from the surface and may contribute to the present

  15. The image in print advertising and comments to Val Larsen's research program

    DEFF Research Database (Denmark)

    Sørensen, Bent; Thellefsen, Torkild Leo; Thellefsen, Martin Muderspach

    2017-01-01

    In this article, the authors re-visit, with Val Larsen, the use of Peircean icons and symbols in print advertising and thereby find (some) formal conditions concerning its images. Even though they are inspired by Val Larsen's research program the authors are also critical of it. Hence, they set out...... to demonstrate how Val Larsen overlooks crucial parts of the semiotic potential of icons and symbols within print advertising. Furthermore, Val Larsen needs, they argue, the Peircean index within his research program. At the end of the article, and inspired by Val Larsen, the authors put forth nine Peircean...... points they find relevant for a research program concerning the image within print advertising. Here, ontological and methodological deductions are made from Peircean ideas and principles....

  16. The Levy sections theorem revisited

    International Nuclear Information System (INIS)

    Figueiredo, Annibal; Gleria, Iram; Matsushita, Raul; Silva, Sergio Da

    2007-01-01

    This paper revisits the Levy sections theorem. We extend the scope of the theorem to time series and apply it to historical daily returns of selected dollar exchange rates. The elevated kurtosis usually observed in such series is then explained by their volatility patterns. And the duration of exchange rate pegs explains the extra elevated kurtosis in the exchange rates of emerging markets. In the end, our extension of the theorem provides an approach that is simpler than the more common explicit modelling of fat tails and dependence. Our main purpose is to build up a technique based on the sections that allows one to artificially remove the fat tails and dependence present in a data set. By analysing data through the lenses of the Levy sections theorem one can find common patterns in otherwise very different data sets

  17. The Levy sections theorem revisited

    Science.gov (United States)

    Figueiredo, Annibal; Gleria, Iram; Matsushita, Raul; Da Silva, Sergio

    2007-06-01

    This paper revisits the Levy sections theorem. We extend the scope of the theorem to time series and apply it to historical daily returns of selected dollar exchange rates. The elevated kurtosis usually observed in such series is then explained by their volatility patterns. And the duration of exchange rate pegs explains the extra elevated kurtosis in the exchange rates of emerging markets. In the end, our extension of the theorem provides an approach that is simpler than the more common explicit modelling of fat tails and dependence. Our main purpose is to build up a technique based on the sections that allows one to artificially remove the fat tails and dependence present in a data set. By analysing data through the lenses of the Levy sections theorem one can find common patterns in otherwise very different data sets.

  18. "Rapid Revisit" Measurements of Sea Surface Winds Using CYGNSS

    Science.gov (United States)

    Park, J.; Johnson, J. T.

    2017-12-01

    The Cyclone Global Navigation Satellite System (CYGNSS) is a space-borne GNSS-R (GNSS-Reflectometry) mission that launched December 15, 2016 for ocean surface wind speed measurements. CYGNSS includes 8 small satellites in the same LEO orbit, so that the mission provides wind speed products having unprecedented coverage both in time and space to study multi-temporal behaviors of oceanic winds. The nature of CYGNSS coverage results in some locations on Earth experiencing multiple wind speed measurements within a short period of time (a "clump" of observations in time resulting in a "rapid revisit" series of measurements). Such observations could seemingly provide indications of regions experiencing rapid changes in wind speeds, and therefore be of scientific utility. Temporally "clumped" properties of CYGNSS measurements are investigated using early CYGNSS L1/L2 measurements, and the results show that clump durations and spacing vary with latitude. For example, the duration of a clump can extend as long as a few hours at higher latitudes, with gaps between clumps ranging from 6 to as high as 12 hours depending on latitude. Examples are provided to indicate the potential of changes within a clump to produce a "rapid revisit" product for detecting convective activity. Also, we investigate detector design for identifying convective activities. Results from analyses using recent CYGNSS L2 winds will be provided in the presentation.

  19. Re-visiting RHIC snakes: OPERA fields, n0 dance

    Energy Technology Data Exchange (ETDEWEB)

    Meot, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gupta, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Huang, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ranjbar, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Robert-Demolaize, G. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2017-09-22

    In this Tech. Note RHIC snakes and stable spin direction $\\vector{n}$0(s) are re-visited, based on OPERA-computed field maps of the former. The numerical simulations so undertaken provide various outcomes regarding RHIC optics and spin dynamics, in relation with orbital and focusing effects resulting from the use of this realistic 3-D representation of the snakes.

  20. Enzyme-semiconductor interactions: Routes from fundamental aspects to photoactive devices

    Energy Technology Data Exchange (ETDEWEB)

    Lewerenz, H.J. [Division of Solar Energy, Hahn-Meitner-Institut GmbH, Berlin (Germany)

    2008-09-15

    Scanning tunnelling microscopy (STM) experiments at protein-semiconductor systems are analyzed using concepts from applied semiconductor physics such as Fermi level pinning and MIS (metal-insulator-semiconductor) junction electronics. Routes for immobilization of enzymes (proteins) on nanostructured surfaces of MoTe{sub 2} and Si are outlined using so-called DLVO and non-DLVO interaction forces. An overview of the catalytic activity of the imaged enzymes, reverse transcriptases of the retroviruses HIV 1 and AMV (avian myeloblastosis virus), is given including their tertiary structural properties which is revealed also in the STM and tapping mode AFM images. For the interpretation of STM images, a resonant charge transfer mechanism is invoked, based on the potential dependence of the image contrast and the energy band structure of MoTe{sub 2} near the valence band maximum. First analyses of the charge transport from the semiconductor to the STM tip at negative bias of MoTe{sub 2} suggest that the observed uninhibited conductivity in the constant current experiments results from solvation-assisted release of electrons from traps that exist along the polypeptide chains and that charge transport occurs at the circumference of the enzymes where biological water is present. Therefore, charge injection into catalytically active enzymes such as hydrogenase or water oxidase of photosystem I and II with subsequent charge transport to the active sites appears difficult to realize. Possibilities of radiation-less long-distance energy transfer based on the Foerster mechanism, its multichromic extension and on Dexter exciton hopping are considered for catalytically active hybrid inorganic/organic absorber-enzyme structures. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Spin polarized tunnelling investigation of nanometre Co clusters by means of a Ni bulk tip

    International Nuclear Information System (INIS)

    Rastei, M V; Bucher, J P

    2006-01-01

    A massive Ni tip is used in spin polarized scanning tunnelling microscopy (SP STM) to explore the magnetization state of nanometre Co clusters, self-organized on the Au(111) surface. Constant current STM images taken at 4.6 K show a bimodal distribution of the cluster heights, accounting for the spin polarization of the STM junction. The spin polarization of the tunnel junction as a function of the bias voltage is found to depend on the local density of states of the sample examined. Changing the vacuum barrier parameters by bringing the tip closer to the surface leads to a reduction in the tunnelling magnetoresistance that may be attributed to spin flip effects. (letter to the editor)

  2. Scanning tunneling microscope with two-dimensional translator.

    Science.gov (United States)

    Nichols, J; Ng, K-W

    2011-01-01

    Since the invention of the scanning tunneling microscope (STM), it has been a powerful tool for probing the electronic properties of materials. Typically STM designs capable of obtaining resolution on the atomic scale are limited to a small area which can be probed. We have built an STM capable of coarse motion in two dimensions, the z- and x-directions which are, respectively, parallel and perpendicular to the tip. This allows us to image samples with very high resolution at sites separated by macroscopic distances. This device is a single unit with a compact design making it very stable. It can operate in either a horizontal or vertical configuration and at cryogenic temperatures.

  3. Development of micro-four-point probe in a scanning tunneling microscope for in situ electrical transport measurement.

    Science.gov (United States)

    Ge, Jian-Feng; Liu, Zhi-Long; Gao, Chun-Lei; Qian, Dong; Liu, Canhua; Jia, Jin-Feng

    2015-05-01

    Electrons at surface may behave differently from those in bulk of a material. Multi-functional tools are essential in comprehensive studies on a crystal surface. Here, we developed an in situ microscopic four-point probe (4PP) transport measurement system on the basis of a scanning tunneling microscope (STM). In particular, convenient replacement between STM tips and micro-4PPs enables systematic investigations of surface morphology, electronic structure, and electrical transport property of a same sample surface. Performances of the instrument are demonstrated with high-quality STM images, tunneling spectra, and low-noise electrical I-V characteristic curves of a single-layer FeSe film grown on a conductive SrTiO3 surface.

  4. Fabrication of silver tips for scanning tunneling microscope induced luminescence.

    Science.gov (United States)

    Zhang, C; Gao, B; Chen, L G; Meng, Q S; Yang, H; Zhang, R; Tao, X; Gao, H Y; Liao, Y; Dong, Z C

    2011-08-01

    We describe a reliable fabrication procedure of silver tips for scanning tunneling microscope (STM) induced luminescence experiments. The tip was first etched electrochemically to yield a sharp cone shape using selected electrolyte solutions and then sputter cleaned in ultrahigh vacuum to remove surface oxidation. The tip status, in particular the tip induced plasmon mode and its emission intensity, can be further tuned through field emission and voltage pulse. The quality of silver tips thus fabricated not only offers atomically resolved STM imaging, but more importantly, also allows us to perform challenging "color" photon mapping with emission spectra taken at each pixel simultaneously during the STM scan under relatively small tunnel currents and relatively short exposure time.

  5. Development of micro-four-point probe in a scanning tunneling microscope for in situ electrical transport measurement

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Jian-Feng; Liu, Zhi-Long; Gao, Chun-Lei; Qian, Dong; Liu, Canhua, E-mail: canhualiu@sjtu.edu.cn, E-mail: jfjia@sjtu.edu.cn; Jia, Jin-Feng, E-mail: canhualiu@sjtu.edu.cn, E-mail: jfjia@sjtu.edu.cn [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2015-05-15

    Electrons at surface may behave differently from those in bulk of a material. Multi-functional tools are essential in comprehensive studies on a crystal surface. Here, we developed an in situ microscopic four-point probe (4PP) transport measurement system on the basis of a scanning tunneling microscope (STM). In particular, convenient replacement between STM tips and micro-4PPs enables systematic investigations of surface morphology, electronic structure, and electrical transport property of a same sample surface. Performances of the instrument are demonstrated with high-quality STM images, tunneling spectra, and low-noise electrical I-V characteristic curves of a single-layer FeSe film grown on a conductive SrTiO{sub 3} surface.

  6. Organized single-molecule magnets: direct observation of new Mn12 derivatives on gold

    International Nuclear Information System (INIS)

    Cornia, A.; Fabretti, A.C.; Pacchioni, M.; Zobbi, L.; Bonacchi, D.; Caneschi, A.; Gatteschi, D.; Biagi, R.; Del Pennino, U.; De Renzi, V.; Gurevich, L.; Zant, H.S.J. van der

    2004-01-01

    Gold adsorbates of the dodecamanganese(III,IV) single-molecule magnet (SMM) [Mn 12 O 12 (L) 16 (H 2 O) 4 ] where L=16-(acetylthio)hexadecanoate have been prepared and investigated by X-ray photoelectron spectroscopy and scanning tunneling microscopy (STM). The successful imaging of Mn 12 molecules by STM represents a first step toward the magnetic addressing of individual SMMs and the development of molecule-based devices for magnetic information storage

  7. Towards Cluster-Assembled Materials of True Monodispersity in Size and Chemical Environment: Synthesis, Dynamics and Activity

    Science.gov (United States)

    2016-10-27

    thermodynamic and kinetic cluster size control on periodically wet - table surfaces, new questions came up concerning the link between diffusivity and...from ring-hollow (H,F) to ring-bridge (B). Left: STM annealing series (50×50 nm2), Moiré cell scheme and cluster position evaluation. Pd clus- ters...growth at T>700 K. Below: Measured and theoretically simulated (insets) STM images of various stages in the dehydrogenation process upon annealing

  8. Scanning Tunneling Microscopy Study of Carbon Tetrachloride Adsorption and Degradation on a Natural a-Fe2O3(0001) Surface in Ultrahigh Vacuum

    Science.gov (United States)

    Taeg Rim, Kwang; Fitts, Jeffrey; Adib, Kaveh; Camillone, Nicholas, III; Schlosser, Peter; Osgood, Richard, Jr.; Flynn, George; Joyce, Stephen

    2001-03-01

    Scanning tunneling microscopy and low energy electron diffraction have been used to study a natural a-Fe2O3(0001) surface and the adsorption and degradation of carbon tetrachloride on the reduced Fe3O4(111) terminated surface. A natural a-Fe2O3 (0001) surface was prepared by repeated cycles of Ar+ ion sputtering and annealing in vacuum or in O2 at 850 K. STM images and a LEED pattern indicate that an Fe3O4(111) terminated surface and a bi-phase can be formed depending on annealing conditions. The Fe3O4(111) terminated surface was dosed with CCl4 at room temperature, and flashed up to 590 K and 850 K. STM images show adsorbates on the surface at room temperature and the degradation products of CCl4 are isolated on the surface as the flashing temperature increases up to 850 K. Results from a companion temperature programmed desorption investigation are used in conjunction with the STM images to propose site specific reactions of CCl4 on the Fe3O4(111) terminated surface.

  9. Direct observation of X-ray induced atomic motion using scanning tunneling microscope combined with synchrotron radiation.

    Science.gov (United States)

    Saito, Akira; Tanaka, Takehiro; Takagi, Yasumasa; Hosokawa, Hiromasa; Notsu, Hiroshi; Ohzeki, Gozo; Tanaka, Yoshihito; Kohmura, Yoshiki; Akai-Kasaya, Megumi; Ishikawa, Tetsuya; Kuwahara, Yuji; Kikuta, Seishi; Aono, Masakazu

    2011-04-01

    X-ray induced atomic motion on a Ge(111)-c(2 x 8) clean surface at room temperature was directly observed with atomic resolution using a synchrotron radiation (SR)-based scanning tunneling microscope (STM) system under ultra high vacuum condition. The atomic motion was visualized as a tracking image by developing a method to merge the STM images before and after X-ray irradiation. Using the tracking image, the atomic mobility was found to be strongly affected by defects on the surface, but was not dependent on the incident X-ray energy, although it was clearly dependent on the photon density. The atomic motion can be attributed to surface diffusion, which might not be due to core-excitation accompanied with electronic transition, but a thermal effect by X-ray irradiation. The crystal surface structure was possible to break even at a lower photon density than the conventionally known barrier. These results can alert X-ray studies in the near future about sample damage during measurements, while suggesting the possibility of new applications. Also the obtained results show a new availability of the in-situ SR-STM system.

  10. Serotype-specific mortality from invasive Streptococcus pneumoniae disease revisited

    DEFF Research Database (Denmark)

    Martens, Pernille; Worm, Signe Westring; Lundgren, Bettina

    2004-01-01

    Serotype-specific mortality from invasive Streptococcus pneumoniae disease revisited.Martens P, Worm SW, Lundgren B, Konradsen HB, Benfield T. Department of Infectious Diseases 144, Hvidovre University Hospital, DK-2650 Hvidovre, Denmark. pernillemartens@yahoo.com BACKGROUND: Invasive infection...... with Streptococcus pneumoniae (pneumococci) causes significant morbidity and mortality. Case series and experimental data have shown that the capsular serotype is involved in the pathogenesis and a determinant of disease outcome. METHODS: Retrospective review of 464 cases of invasive disease among adults diagnosed...

  11. Heteroepitaxial growth and surface structure of L1{sub 0}-MnGa(111) ultra-thin films on GaN(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Mandru, Andrada-Oana; Wang, Kangkang; Cooper, Kevin; Ingram, David C.; Smith, Arthur R. [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Garcia Diaz, Reyes; Takeuchi, Noboru [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autónoma de México, Apartado Postal 14, Ensenada Baja California, Codigo Postal 22800 (Mexico); Haider, Muhammad [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran, 31261 (Saudi Arabia)

    2013-10-14

    L1{sub 0}-structured MnGa(111) ultra-thin films were heteroepitaxially grown on GaN(0001) under lightly Mn-rich conditions using molecular beam epitaxy. Room-temperature scanning tunneling microscopy (STM) investigations reveal smooth terraces and angular step edges, with the surface structure consisting primarily of a 2 × 2 reconstruction along with small patches of 1 × 2. Theoretical calculations were carried out using density functional theory, and the simulated STM images were calculated using the Tersoff-Hamman approximation, revealing that a stoichiometric 1 × 2 and a Mn-rich 2 × 2 surface structure give the best agreement with the observed experimental images.

  12. Mono- and multilayers of molecular spoked carbazole wheels on graphite.

    Science.gov (United States)

    Jester, Stefan-S; Aggarwal, A Vikas; Kalle, Daniel; Höger, Sigurd

    2014-01-01

    Self-assembled monolayers of a molecular spoked wheel (a shape-persistent macrocycle with an intraannular spoke/hub system) and its synthetic precursor are investigated by scanning tunneling microscopy (STM) at the liquid/solid interface of 1-octanoic acid and highly oriented pyrolytic graphite. The submolecularly resolved STM images reveal that the molecules indeed behave as more or less rigid objects of certain sizes and shapes - depending on their chemical structures. In addition, the images provide insight into the multilayer growth of the molecular spoked wheels (MSWs), where the first adlayer acts as a template for the commensurate adsorption of molecules in the second layer.

  13. Mono- and multilayers of molecular spoked carbazole wheels on graphite

    Directory of Open Access Journals (Sweden)

    Stefan-S. Jester

    2014-11-01

    Full Text Available Self-assembled monolayers of a molecular spoked wheel (a shape-persistent macrocycle with an intraannular spoke/hub system and its synthetic precursor are investigated by scanning tunneling microscopy (STM at the liquid/solid interface of 1-octanoic acid and highly oriented pyrolytic graphite. The submolecularly resolved STM images reveal that the molecules indeed behave as more or less rigid objects of certain sizes and shapes – depending on their chemical structures. In addition, the images provide insight into the multilayer growth of the molecular spoked wheels (MSWs, where the first adlayer acts as a template for the commensurate adsorption of molecules in the second layer.

  14. The Assassination of John F. Kennedy: Revisiting the Medical Data

    OpenAIRE

    Rohrich, Rod J.; Nagarkar, Purushottam; Stokes, Mike; Weinstein, Aaron; Mantik, David W.; Jensen, J. Arthur

    2014-01-01

    Thank you for publishing "The Assassination of John F. Kennedy: Revisiting the Medical Data."1 The central conclusion of this study is that the assassination remains controversial and that some of the controversy must be attributable to the "reporting and handling of the medical evidence." With the greatest respect for you and Dr. Robert McClelland, let me argue that your text and on-line interviews perpetuate the central misunderstanding of the assassination and there...

  15. Dispute Resolution and Technology: Revisiting the Justification of Conflict Management

    OpenAIRE

    Koulu, Riikka

    2016-01-01

    This study, Dispute Resolution and Technology: Revisiting the Justification of Conflict Management, belongs to the fields of procedural law, legal theory and law and technology studies. In this study the changes in dispute resolution caused by technology are evaluated. The overarching research question of this study is how does implementing technology to dispute resolution challenge the justification of law as a legitimised mode of violence? Before answering such an abstract research question...

  16. Deja vu: The Unified Command Plan of the Future Revisited

    Science.gov (United States)

    2011-05-19

    Approved for Public Release; Distribution is Unlimited Déjà vu : The Unified Command Plan of the Future Revisited A Monograph by Lieutenant...DD-MM-YYYY) 19-05-2011 2. REPORT TYPE Monograph 3. DATES COVERED (From - To) JUL 2010 – MAY 2011 4. TITLE AND SUBTITLE Déjà vu : The Unified...i SCHOOL OF ADVANCED MILITARY STUDIES MONOGRAPH APPROVAL Lieutenant Colonel Edward Francis Martignetti Title of Monograph: Déjà vu : The Unified

  17. Interpretation of transport barriers and of subneoclassical transport in the framework of the revisited neoclassical theory

    International Nuclear Information System (INIS)

    Rogister, A.L.

    1999-01-01

    'Subneoclassical' heat fluxes are predicted in the high collisionality regime by the revisited neoclassical theory, which includes the roles of Finite Larmor Radius effects and Inertia, that we published earlier. Unlike conventional neoclassical theory, the revisited theory further provides a non degenerate ambipolarity constraint which defines unambiguously the radial electric field. Together with the parallel momentum equation, the ambipolarity constraint leads, under some conditions, to radial electric field profiles with high negative shear akin to those observed in spontaneous edge transport barriers. The predictions of the theory are outlined, with emphasis laid on the interpretation of experimental results such as magnitude of the jumps, width of the shear layer, local scaling laws. Extension of the theory to triggered transitions and cold pulse propagation studies is suggested. (author)

  18. How does the Ambience of Cafe Affect the Revisit Intention Among its Patrons? A S on the Cafes in Ipoh, Perak

    Directory of Open Access Journals (Sweden)

    AbuThahir Sharmeela-Banu Syed

    2018-01-01

    Full Text Available Food service industry is growing rapidly as a result of the changing consumer lifestyle. The food service industry is highly competitive due to the increasing number of new entrants offering inventive food products and services. In order to be outstanding in such competitive industry, retailers nowadays opt to emphasize on their store environment. Past studies discovered that store environment stimulates emotions that significantly boost customer revisit intention. As a result, retailers attempt to differentiate their store by combining various environmental stimuli to create an attractive ambience that will in turn draw in the customers. Hence, this study attempts to investigate the impact of various café ambience factors on the patrons’ revisit intention. The patrons of cafes in Ipoh, Perak were selected using purposive sampling technique to be the respondents of this study. 250 questionnaires were collected and Partial Least Square technique was used to analyse the data collected. Findings show that all the five factors of café ambience namely lighting, music, decoration, cleanliness and layouts were significantly influencing the patrons’ revisit intention. Of these five factors, lighting was most influential while music was the least influential in affecting the patrons’ revisit intention. Accordingly, this study lists several recommendations for practitioners and academics with regards to the store environment and its impact on the repurchase intention.

  19. High Pressure Scanning Tunneling Microscopy Studies of Adsorbate Structure and Mobility during Catalytic Reactions. Novel Design of an Ultra High Pressure, High Temperature Scanning Tunneling Microscope System for Probing Catalytic Conversions

    International Nuclear Information System (INIS)

    Tang, David Chi-Wai

    2005-01-01

    The aim of the work presented therein is to take advantage of scanning tunneling microscope's (STM) capability for operation under a variety of environments under real time and at atomic resolution to monitor adsorbate structures and mobility under high pressures, as well as to design a new generation of STM systems that allow imaging in situ at both higher pressures (35 atm) and temperatures (350 C). The design of a high pressure, high temperature scanning tunneling microscope system, that is capable of monitoring reactions in situ at conditions from UHV and ambient temperature up to 1 atm and 250 C, is briefly presented along with vibrational and thermal analysis, as this system serves as a template to improve upon during the design of the new ultra high pressure, high temperature STM. Using this existing high pressure scanning tunneling microscope we monitored the co-adsorption of hydrogen, ethylene and carbon dioxide on platinum (111) and rhodium (111) crystal faces in the mTorr pressure range at 300 K in equilibrium with the gas phase. During the catalytic hydrogenation of ethylene to ethane in the absence of CO the metal surfaces are covered by an adsorbate layer that is very mobile on the time scale of STM imaging. We found that the addition of CO poisons the hydrogenation reaction and induces ordered structures on the single crystal surfaces. Several ordered structures were observed upon CO addition to the surfaces pre-covered with hydrogen and ethylene: a rotated (√19 x √19)R23.4 o on Pt(111), and domains of c(4 x 2)-CO+C 2 H 3 , previously unobserved (4 x 2)-CO+3C 2 H 3 , and (2 x 2)-3CO on Rh(111). A mechanism for CO poisoning of ethylene hydrogenation on the metal single crystals was proposed, in which CO blocks surface metal sites and reduces adsorbate mobility to limit adsorption and reaction rate of ethylene and hydrogen. In order to observe heterogeneous catalytic reactions that occur well above ambient pressure and temperature that more closely

  20. Variance in parametric images: direct estimation from parametric projections

    International Nuclear Information System (INIS)

    Maguire, R.P.; Leenders, K.L.; Spyrou, N.M.

    2000-01-01

    Recent work has shown that it is possible to apply linear kinetic models to dynamic projection data in PET in order to calculate parameter projections. These can subsequently be back-projected to form parametric images - maps of parameters of physiological interest. Critical to the application of these maps, to test for significant changes between normal and pathophysiology, is an assessment of the statistical uncertainty. In this context, parametric images also include simple integral images from, e.g., [O-15]-water used to calculate statistical parametric maps (SPMs). This paper revisits the concept of parameter projections and presents a more general formulation of the parameter projection derivation as well as a method to estimate parameter variance in projection space, showing which analysis methods (models) can be used. Using simulated pharmacokinetic image data we show that a method based on an analysis in projection space inherently calculates the mathematically rigorous pixel variance. This results in an estimation which is as accurate as either estimating variance in image space during model fitting, or estimation by comparison across sets of parametric images - as might be done between individuals in a group pharmacokinetic PET study. The method based on projections has, however, a higher computational efficiency, and is also shown to be more precise, as reflected in smooth variance distribution images when compared to the other methods. (author)

  1. Revisiting reflexology: Concept, evidence, current practice, and practitioner training

    OpenAIRE

    Embong, Nurul Haswani; Soh, Yee Chang; Ming, Long Chiau; Wong, Tin Wui

    2015-01-01

    Reflexology is basically a study of how one part of the human body relates to another part of the body. Reflexology practitioners rely on the reflexes map of the feet and hands to all the internal organs and other human body parts. They believe that by applying the appropriate pressure and massage certain spots on the feet and hands, all other body parts could be energized and rejuvenated. This review aimed to revisit the concept of reflexology and examine its effectiveness, practices, and th...

  2. An Excitatory Neural Assembly Encodes Short-Term Memory in the Prefrontal Cortex

    Directory of Open Access Journals (Sweden)

    Yonglu Tian

    2018-02-01

    Full Text Available Short-term memory (STM is crucial for animals to hold information for a small period of time. Persistent or recurrent neural activity, together with neural oscillations, is known to encode the STM at the cellular level. However, the coding mechanisms at the microcircuitry level remain a mystery. Here, we performed two-photon imaging on behaving mice to monitor the activity of neuronal microcircuitry. We discovered a neuronal subpopulation in the medial prefrontal cortex (mPFC that exhibited emergent properties in a context-dependent manner underlying a STM-like behavior paradigm. These neuronal subpopulations exclusively comprise excitatory neurons and mainly represent a group of neurons with stronger functional connections. Microcircuitry plasticity was maintained for minutes and was absent in an animal model of Alzheimer’s disease (AD. Thus, these results point to a functional coding mechanism that relies on the emergent behavior of a functionally defined neuronal assembly to encode STM.

  3. Partially Overlapping Sensorimotor Networks Underlie Speech Praxis and Verbal Short-Term Memory: Evidence from Apraxia of Speech Following Acute Stroke

    Directory of Open Access Journals (Sweden)

    Gregory eHickok

    2014-08-01

    Full Text Available We tested the hypothesis that motor planning and programming of speech articulation and verbal short-term memory (vSTM depend on partially overlapping networks of neural regions. We evaluated this proposal by testing 76 individuals with acute ischemic stroke for impairment in motor planning of speech articulation (apraxia of speech; AOS and vSTM in the first day of stroke, before the opportunity for recovery or reorganization of structure-function relationships. We also evaluate areas of both infarct and low blood flow that might have contributed to AOS or impaired vSTM in each person. We found that AOS was associated with tissue dysfunction in motor-related areas (posterior primary motor cortex, pars opercularis; premotor cortex, insula and sensory-related areas (primary somatosensory cortex, secondary somatosensory cortex, parietal operculum/auditory cortex; while impaired vSTM was associated with primarily motor-related areas (pars opercularis and pars triangularis, premotor cortex, and primary motor cortex. These results are consistent with the hypothesis, also supported by functional imaging data, that both speech praxis and vSTM rely on partially overlapping networks of brain regions.

  4. The Influence of Destination Image on Medical Tourist’s Intention for Future Destination Choice

    Directory of Open Access Journals (Sweden)

    Norhaslin Abu Hassan

    2016-01-01

    Full Text Available This study proposed to explore how the image of a destination could influence medical tourists in choosing a destination as their future medical and tourism destination choice. Scholars argued that destination image had a significant relationship with behavioral intentions. Destination image influence not only the decision-making process but also conditions after-decision-making behaviors of tourists. In the current study context, the future destination choice behavior referred to the intention to revisit the previous destination and the intention to spread the positive word-of-mouth to others. For this study, inbound medical tourists from private hospitals registered with Malaysia Healthcare Travel Council (MHTC in Penang, Malacca, Kuala Lumpur and Selangor in Malaysia will be approached quantitatively by survey questionnaires. This study will contribute to an understanding of the significant factors influencing medical tourists’ intention for future destination choice.

  5. Revisiting the Metaphor of the Island: Challenging "World Culture" from an Island Misunderstood

    Science.gov (United States)

    Rappleye, Jeremy

    2015-01-01

    This article revisits the newly "discovered" island that world culture theorists have repeatedly utilised to explain their theoretical stance, conceptual preferences and methodological approach. Yet, it seeks to (re)connect world culture with the real world by replacing their imagined atoll with a real one--the island-nation of Japan. In…

  6. Organized single-molecule magnets: direct observation of new Mn{sub 12} derivatives on gold

    Energy Technology Data Exchange (ETDEWEB)

    Cornia, A.; Fabretti, A.C.; Pacchioni, M.; Zobbi, L. E-mail: lzobbi@unimo.it; Bonacchi, D.; Caneschi, A.; Gatteschi, D.; Biagi, R.; Del Pennino, U.; De Renzi, V.; Gurevich, L.; Zant, H.S.J. van der

    2004-05-01

    Gold adsorbates of the dodecamanganese(III,IV) single-molecule magnet (SMM) [Mn{sub 12}O{sub 12}(L){sub 16}(H{sub 2}O){sub 4}] where L=16-(acetylthio)hexadecanoate have been prepared and investigated by X-ray photoelectron spectroscopy and scanning tunneling microscopy (STM). The successful imaging of Mn{sub 12} molecules by STM represents a first step toward the magnetic addressing of individual SMMs and the development of molecule-based devices for magnetic information storage.

  7. Commendable surface physics by means of scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Besenbacher, F.; Laegsgaard, E.; Stensgard, I.

    1995-01-01

    The scanning tunneling microscope, developed at the Aarhus University (Denmark) allows taking several STM images per second, as opposite to other similar microscopes, where the typical scanning time is 0,5-1 min. This new system enables collecting of important information concerning dynamic processes on the surfaces. The Aarhus microscope is very stable, hence atomic resolution is achievable even on close-packed metallic surfaces, while it is difficult to achieve by means of the conventional STM. (EG)

  8. Thalamo-Cortical Disruption Contributes to Short-Term Memory Deficits in Patients with Medial Temporal Lobe Damage.

    Science.gov (United States)

    Voets, Natalie L; Menke, Ricarda A L; Jbabdi, Saad; Husain, Masud; Stacey, Richard; Carpenter, Katherine; Adcock, Jane E

    2015-11-01

    Short-term (STM) and long-term memory (LTM) have largely been considered as separate brain systems reflecting fronto-parietal and medial temporal lobe (MTL) functions, respectively. This functional dichotomy has been called into question by evidence of deficits on aspects of working memory in patients with MTL damage, suggesting a potentially direct hippocampal contribution to STM. As the hippocampus has direct anatomical connections with the thalamus, we tested the hypothesis that damage to thalamic nuclei regulating cortico-cortical interactions may contribute to STM deficits in patients with hippocampal dysfunction. We used diffusion-weighted magnetic resonance imaging-based tractography to identify anatomical subdivisions in patients with MTL epilepsy. From these, we measured resting-state functional connectivity with detailed cortical divisions of the frontal, temporal, and parietal lobes. Whereas thalamo-temporal functional connectivity reflected LTM performance, thalamo-prefrontal functional connectivity specifically predicted STM performance. Notably, patients with hippocampal volume loss showed thalamic volume loss, most prominent in the pulvinar region, not detected in patients with normal hippocampal volumes. Aberrant thalamo-cortical connectivity in the epileptic hemisphere was mirrored in a loss of behavioral association with STM performance specifically in patients with hippocampal atrophy. These findings identify thalamo-cortical disruption as a potential mechanism contributing to STM deficits in the context of MTL damage. © The Author 2015. Published by Oxford University Press.

  9. Revisiting R-invariant direct gauge mediation

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Cheng-Wei [Center for Mathematics and Theoretical Physics andDepartment of Physics, National Central University,Taoyuan, Taiwan 32001, R.O.C. (China); Institute of Physics, Academia Sinica,Taipei, Taiwan 11529, R.O.C. (China); Physics Division, National Center for Theoretical Sciences,Hsinchu, Taiwan 30013, R.O.C. (China); Kavli IPMU (WPI), UTIAS, University of Tokyo,Kashiwa, Chiba 277-8583 (Japan); Harigaya, Keisuke [Department of Physics, University of California,Berkeley, California 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory,Berkeley, California 94720 (United States); ICRR, University of Tokyo,Kashiwa, Chiba 277-8582 (Japan); Ibe, Masahiro [Kavli IPMU (WPI), UTIAS, University of Tokyo,Kashiwa, Chiba 277-8583 (Japan); ICRR, University of Tokyo,Kashiwa, Chiba 277-8582 (Japan); Yanagida, Tsutomu T. [Kavli IPMU (WPI), UTIAS, University of Tokyo,Kashiwa, Chiba 277-8583 (Japan)

    2016-03-21

    We revisit a special model of gauge mediated supersymmetry breaking, the “R-invariant direct gauge mediation.” We pay particular attention to whether the model is consistent with the minimal model of the μ-term, i.e., a simple mass term of the Higgs doublets in the superpotential. Although the incompatibility is highlighted in view of the current experimental constraints on the superparticle masses and the observed Higgs boson mass, the minimal μ-term can be consistent with the R-invariant gauge mediation model via a careful choice of model parameters. We derive an upper limit on the gluino mass from the observed Higgs boson mass. We also discuss whether the model can explain the 3σ excess of the Z+jets+E{sub T}{sup miss} events reported by the ATLAS collaboration.

  10. Revisiting kaon physics in general Z scenario

    Directory of Open Access Journals (Sweden)

    Motoi Endo

    2017-08-01

    Full Text Available New physics contributions to the Z penguin are revisited in the light of the recently-reported discrepancy of the direct CP violation in K→ππ. Interference effects between the standard model and new physics contributions to ΔS=2 observables are taken into account. Although the effects are overlooked in the literature, they make experimental bounds significantly severer. It is shown that the new physics contributions must be tuned to enhance B(KL→π0νν¯, if the discrepancy of the direct CP violation is explained with satisfying the experimental constraints. The branching ratio can be as large as 6×10−10 when the contributions are tuned at the 10% level.

  11. Revisiting the Decision of Death in Hurst v. Florida.

    Science.gov (United States)

    Cooke, Brian K; Ginory, Almari; Zedalis, Jennifer

    2016-12-01

    The United States Supreme Court has considered the question of whether a judge or a jury must make the findings necessary to support imposition of the death penalty in several notable cases, including Spaziano v. Florida (1984), Hildwin v. Florida (1989), and Ring v. Arizona (2002). In 2016, the U.S. Supreme Court revisited the subject in Hurst v. Florida Florida Statute § 921.141 allows the judge, after weighing aggravating and mitigating circumstances, to enter a sentence of life imprisonment or death. Before Hurst, Florida's bifurcated sentencing proceedings included an advisory sentence from jurors and a separate judicial hearing without juror involvement. In Hurst, the Court revisited the question of whether Florida's capital sentencing scheme violates the Sixth Amendment, which requires a jury, not a judge, to find each fact necessary to impose a sentence of death in light of Ring In an eight-to-one decision, the Court reversed the judgment of the Florida Supreme Court, holding that the Sixth Amendment requires a jury to find the aggravating factors necessary for imposing the death penalty. The role of Florida juries in capital sentencing proceedings was thereby elevated from advisory to determinative. We examine the Court's decision and offer commentary regarding this shift from judge to jury in the final imposition of the death penalty and the overall effect of this landmark case. © 2016 American Academy of Psychiatry and the Law.

  12. Vibrational spectra of nanowires measured using laser doppler vibrometry and STM studies of epitaxial graphene : an LDRD fellowship report.

    Energy Technology Data Exchange (ETDEWEB)

    Biedermann, Laura Butler

    2009-09-01

    MWNTs, their vibration spectra was more extensively studied. The thermal vibration spectra of Ag{sub 2}Ga nanoneedles was measured under both ambient and low-vacuum conditions. The operational deflection shapes of the vibrating Ag{sub 2}Ga nanoneedles was also measured, allowing confirmation of the eigenmodes of vibration. The modulus of the crystalline nanoneedles was 84.3 {+-} 1.0 GPa. Gas damping is the dominate mechanism of energy loss for nanowires oscillating under ambient conditions. The measured quality factors, Q, of oscillation are in line with theoretical predictions of air damping in the free molecular gas damping regime. In the free molecular regime, Q{sub gas} is linearly proportional to the density and diameter of the nanowire and inversely proportional to the air pressure. Since the density of the Ag{sub 2}Ga nanoneedles is three times that of the MWNTs, the Ag{sub 2}Ga nanoneedles have greater Q at atmospheric pressures. Our initial measurements of Q for Ag{sub 2}Ga nanoneedles in low-vacuum (10 Torr) suggest that the intrinsic Q of these nanoneedles may be on the order of 1000. The epitaxial carbon that grows after heating (000{bar 1}) silicon carbide (SiC) to high temperatures (1450-1600) in vacuum was also studied. At these high temperatures, the surface Si atoms sublime and the remaining C atoms reconstruct to form graphene. X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM) were used to characterize the quality of the few-layer graphene (FLG) surface. The XPS studies were useful in confirming the graphitic composition and measuring the thickness of the FLG samples. STM studies revealed a wide variety of nanometer-scale features that include sharp carbon-rich ridges, moire superlattices, one-dimensional line defects, and grain boundaries. By imaging these features with atomic scale resolution, considerable insight into the growth mechanisms of FLG on the carbon-face of SiC is obtained.

  13. Galactic rings revisited - I. CVRHS classifications of 3962 ringed galaxies from the Galaxy Zoo 2 Database

    Science.gov (United States)

    Buta, Ronald J.

    2017-11-01

    Rings are important and characteristic features of disc-shaped galaxies. This paper is the first in a series that re-visits galactic rings with the goals of further understanding the nature of the features and for examining their role in the secular evolution of galaxy structure. The series begins with a new sample of 3962 galaxies drawn from the Galaxy Zoo 2 citizen science data base, selected because zoo volunteers recognized a ring-shaped pattern in the morphology as seen in Sloan Digital Sky Survey colour images. The galaxies are classified within the framework of the Comprehensive de Vaucouleurs revised Hubble-Sandage system. It is found that zoo volunteers cued on the same kinds of ring-like features that were recognized in the 1995 Catalogue of Southern Ringed Galaxies. This paper presents the full catalogue of morphological classifications, comparisons with other sources of classifications and some histograms designed mainly to highlight the content of the catalogue. The advantages of the sample are its large size and the generally good quality of the images; the main disadvantage is the low physical resolution that limits the detectability of linearly small rings such as nuclear rings. The catalogue includes mainly inner and outer disc rings and lenses. Cataclysmic (`encounter-driven') rings (such as ring and polar ring galaxies) are recognized in less than 1 per cent of the sample.

  14. Magnetic moments revisited

    International Nuclear Information System (INIS)

    Towner, I.S.; Khanna, F.C.

    1984-01-01

    Consideration of core polarization, isobar currents and meson-exchange processes gives a satisfactory understanding of the ground-state magnetic moments in closed-shell-plus (or minus)-one nuclei, A = 3, 15, 17, 39 and 41. Ever since the earliest days of the nuclear shell model the understanding of magnetic moments of nuclear states of supposedly simple configurations, such as doubly closed LS shells +-1 nucleon, has been a challenge for theorists. The experimental moments, which in most cases are known with extraordinary precision, show a small yet significant departure from the single-particle Schmidt values. The departure, however, is difficult to evaluate precisely since, as will be seen, it results from a sensitive cancellation between several competing corrections each of which can be as large as the observed discrepancy. This, then, is the continuing fascination of magnetic moments. In this contribution, we revisit the subjet principally to identify the role played by isobar currents, which are of much concern at this conference. But in so doing we warn quite strongly of the dangers of considering just isobar currents in isolation; equal consideration must be given to competing processes which in this context are the mundane nuclear structure effects, such as core polarization, and the more popular meson-exchange currents

  15. Growth of the firm and foreign trade: Adrian Wood's theory revisited

    OpenAIRE

    Catermol, Fabrício

    2006-01-01

    This paper analyzes the growth of the firm by foreign trade. The theory of Adrian Wood is revisited for the analysis of growth and profit trade-off and improved to cope with growth by exports. The main outcome of this paper is that low domestic demand can be a very important factor to firm choices growth by foreign market. However, the growth of domestic demand does not necessarily reduce exports.

  16. Revisiting the description of Protein-Protein interfaces. Part II: Experimental study

    OpenAIRE

    Cazals , Frédéric; Proust , Flavien

    2006-01-01

    This paper provides a detailed experimental study of an interface model developed in the companion article F. Cazals and F. Proust, Revisiting the description of Protein-Protein interfaces. Part I: algorithms. Our experimental study is concerned with the usual database of protein-protein complexes, split into five families (Proteases, Immune system, Enzyme Complexes, Signal transduction, Misc.) Our findings, which bear some contradictions with usual statements are the following: (i)Connectivi...

  17. Small-angle scattering theory revisited: Photocurrent and spatial localization

    DEFF Research Database (Denmark)

    Basse, N.P.; Zoletnik, S.; Michelsen, Poul

    2005-01-01

    In this paper theory on collective scattering measurements of electron density fluctuations in fusion plasmas is revisited. We present the first full derivation of the expression for the photocurrent beginning at the basic scattering concepts. Thereafter we derive detailed expressions for the auto......- and crosspower spectra obtained from measurements. These are discussed and simple simulations made to elucidate the physical meaning of the findings. In this context, the known methods of obtaining spatial localization are discussed and appraised. Where actual numbers are applied, we utilize quantities from two...

  18. Article Review: Advanced Change Theory Revisited: An Article Critique

    Directory of Open Access Journals (Sweden)

    R. Scott Pochron

    2008-12-01

    Full Text Available The complexity of life in 21st century society requires new models for leadingand managing change. With that in mind, this paper revisits the model for AdvancedChange Theory (ACT as presented by Quinn, Spreitzer, and Brown in their article,“Changing Others Through Changing Ourselves: The Transformation of HumanSystems” (2000. The authors present ACT as a potential model for facilitating change incomplex organizations. This paper presents a critique of the article and summarizesopportunities for further exploring the model in the light of current trends indevelopmental and integral theory.

  19. Creative Experience and Revisit Intention of Handmade Oriental Parasol Umbrella in Kaohsiung

    OpenAIRE

    Yi-Ju Lee

    2015-01-01

    This study identified the hypothesised relationship between creative experience, and revisit intention of handmade oriental parasol umbrella in Kaohsiung, Taiwan. A face-to-face questionnaire survey was administered in Meinong town, Kaohsiung. The components of creative experience were found as "sense of achievement", "unique learning" and "interaction with instructors" in creative tourism. The result also revealed significant positive relationships between creative exper...

  20. Characteristics of revisits of children at risk for serious infections in pediatric emergency care

    NARCIS (Netherlands)

    E. De Vos-Kerkhof (Evelien); D.H.F. Geurts (Dorien); E.W. Steyerberg (Ewout); M. Lakhanpaul (Monica); H.A. Moll (Henriëtte); R. Oostenbrink (Rianne)

    2018-01-01

    textabstractIn this study, we aimed to identify characteristics of (unscheduled) revisits and its optimal time frame after Emergency Department (ED) discharge. Children with fever, dyspnea, or vomiting/diarrhea (1 month–16 years) who attended the ED of Erasmus MC-Sophia, Rotterdam (2010–2013), the

  1. An Investigation into the Modality Specificity of L2 Learners' STM Abilities in Learning Vocabulary via PDAs

    Directory of Open Access Journals (Sweden)

    Saeed Khazaie

    2012-09-01

    Full Text Available Parallel with the rapid growth of wireless technology and potentials of mobile learning for language teaching/learning, employing mobile devices in language learning seems indispensable. To this end, designing learning materials suitable for different types of mobile devices regarding dual coding (DCT and cognitive load (CLT theories seems inevitable. In this study, multimedia were employed for designing two types of learning materials. Since short-term memory plays an important role in language learning, learners’ visual and verbal short-term memories were taken into consideration, too. 161 L2 Learners aged 19 and 23 years old participated in the major phases of an experiment via personal digital assistant (PDA. Based on their scores on the English vocabulary recognition and recall (EVRR tests and the statistical analysis of the results, it was revealed that delivery of learning materials with pictorial and written annotations combined rather than delivery of learning materials without such annotations to learners with high-visual and high-verbal abilities, learners with high-visual but low-verbal ability, and learners with low-visual but high-verbal ability results in better vocabulary learning outcomes. However, this was not the case for learners with low-visual and low-verbal abilities. This study acknowledges the relation between STM and the relevant modalities of materials presentation.

  2. Probing the location of displayed cytochrome b562 on amyloid by scanning tunnelling microscopy

    International Nuclear Information System (INIS)

    Forman, C J; Barker, P D; Wang, N; Durkan, C; Yang, Z Y; Mowat, C G; Jarvis, S

    2013-01-01

    Amyloid fibres displaying cytochrome b 562 were probed using scanning tunnelling microscopy (STM) in vacuo. The cytochromes are electron transfer proteins containing a haem cofactor and could, in principle, mediate electron transfer between the tip and the gold substrate. If the core fibres were insulating and electron transfer within the 3D haem network was detected, then the electron transport properties of the fibre could be controlled by genetic engineering. Three kinds of STM images were obtained. At a low bias ( 562 was not detected by STM, which was attributed to low adhesion, whereas a monomeric multi-haem protein, GSU1996, was readily imaged. We conclude that the fibre superstructure may be intermittently conducting, that the cytochromes have been seen within the fibres and that they are too far apart for detectable current flow between sites to occur. We predict that GSU1996, being 10 nm long, is more likely to mediate successful electron transfer along the fibre as well as being more readily detectable when displayed from amyloid. (paper)

  3. Hydrogen-induced metallization on Ge(1 1 1) c(2 x 8)

    International Nuclear Information System (INIS)

    Razado, I.C.; Zhang, H.M.; Hansson, G.V.; Uhrberg, R.I.G.

    2006-01-01

    We have studied hydrogen adsorption on the Ge(1 1 1) c(2 x 8) surface using scanning tunneling microscopy (STM) and angle-resolved photoelectron spectroscopy (ARPES). We find that atomic hydrogen preferentially adsorbs on rest atom sites. The neighbouring adatoms appear higher in STM images, which clearly indicates a charge transfer from the rest atom states to the adatom states. The surface states near the Fermi-level have been followed by ARPES as function of H exposure. Initially, there is strong emission from the rest atom states but no emission at the Fermi-level which confirms the semiconducting character of the c(2 x 8) surface. With increasing H exposure a structure develops in the close vicinity of the Fermi-level. The energy position clearly indicates a metallic character of the H-adsorbed surface. Since the only change in the STM images is the increased brightness of the adatoms neighbouring a H-terminated rest atom, we identify the emission at the Fermi-level with these adatom states

  4. Post-Inflationary Gravitino Production Revisited

    CERN Document Server

    Ellis, John; Nanopoulos, Dimitri V.; Olive, Keith A.; Peloso, Marco

    2016-01-01

    We revisit gravitino production following inflation. As a first step, we review the standard calculation of gravitino production in the thermal plasma formed at the end of post-inflationary reheating when the inflaton has completely decayed. Next we consider gravitino production prior to the completion of reheating, assuming that the inflaton decay products thermalize instantaneously while they are still dilute. We then argue that instantaneous thermalization is in general a good approximation, and also show that the contribution of non-thermal gravitino production via the collisions of inflaton decay products prior to thermalization is relatively small. Our final estimate of the gravitino-to-entropy ratio is approximated well by a standard calculation of gravitino production in the post-inflationary thermal plasma assuming total instantaneous decay and thermalization at a time $t \\simeq 1.2/\\Gamma_\\phi$. Finally, in light of our calculations, we consider potential implications of upper limits on the gravitin...

  5. Automatic cloud coverage assessment of Formosat-2 image

    Science.gov (United States)

    Hsu, Kuo-Hsien

    2011-11-01

    Formosat-2 satellite equips with the high-spatial-resolution (2m ground sampling distance) remote sensing instrument. It has been being operated on the daily-revisiting mission orbit by National Space organization (NSPO) of Taiwan since May 21 2004. NSPO has also serving as one of the ground receiving stations for daily processing the received Formosat- 2 images. The current cloud coverage assessment of Formosat-2 image for NSPO Image Processing System generally consists of two major steps. Firstly, an un-supervised K-means method is used for automatically estimating the cloud statistic of Formosat-2 image. Secondly, manual estimation of cloud coverage from Formosat-2 image is processed by manual examination. Apparently, a more accurate Automatic Cloud Coverage Assessment (ACCA) method certainly increases the efficiency of processing step 2 with a good prediction of cloud statistic. In this paper, mainly based on the research results from Chang et al, Irish, and Gotoh, we propose a modified Formosat-2 ACCA method which considered pre-processing and post-processing analysis. For pre-processing analysis, cloud statistic is determined by using un-supervised K-means classification, Sobel's method, Otsu's method, non-cloudy pixels reexamination, and cross-band filter method. Box-Counting fractal method is considered as a post-processing tool to double check the results of pre-processing analysis for increasing the efficiency of manual examination.

  6. Direct STM evidence of a surface interaction between chiral modifier and pro-chiral reagent: Methylacetoacetate on R, R-tartaric acid modified Ni {1 1 1}

    Science.gov (United States)

    Jones, T. E.; Baddeley, C. J.

    2002-11-01

    The asymmetric hydrogenation of methylacetoacetate to R-methyl-3-hydroxybutyrate over R, R-tartaric acid modified Ni catalysts is a well known example of heterogeneous enantioselective catalysis. Using STM, RAIRS and TPD, we investigate the adsorption of methylacetoacetate on Ni{1 1 1} and R, R-TA modified Ni{1 1 1} in order to shed light on the molecular mechanisms underlying the enantioselective catalysis. We show that methylacetoacetate adsorption can only occur in regions of low R, R-tartaric acid coverage. Once adsorption occurs, methylacetoacetate is able to locally rearrange the tartrate modifiers to produce a two-dimensional co-crystal. We consider the implications of our work in explaining the mechanism of enantioselective hydrogenation in this type of system.

  7. Revisiting the Gun Ownership and Violence Link; a multi- level analysis of victimisation survey data.

    NARCIS (Netherlands)

    van Kesteren, J.N.

    2014-01-01

    The link between gun ownership victimisation by violent crime remains one of the most contested issues in criminology. Some authors claim that high gun availability facilitates serious violence. Others claim that gun ownership prevents crime. This article revisits these issues using individual and

  8. Electronic Properties of Functional Biomolecules at Metal/Aqueous Solution Interfaces

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Chi, Qijin; Kuznetsov, A.M.

    2002-01-01

    in electronic properties and stochastic single-molecule features and can be probed by new methods which approach the single-molecule level. Olle of these is in situ scanning tunneling microscopy (STM) in which single-molecule electronic properties directly in aqueous solution are probed. In situ STM combined...... with physical electrochemistry, single-crystal electrodes, and spectroscopic methods is now a new dimension in interfacial bioelectrochemistry. We overview first same approaches to spectroscopic single-molecule imaging, including fluorescence spectroscopy, chemical reaction dynamics, atomic force microscopy...

  9. The Lumbar Lordosis in Males and Females, Revisited.

    Directory of Open Access Journals (Sweden)

    Ori Hay

    Full Text Available Whether differences exist in male and female lumbar lordosis has been debated by researchers who are divided as to the nature of variations in the spinal curve, their origin, reasoning, and implications from a morphological, functional and evolutionary perspective. Evaluation of the spinal curvature is constructive in understanding the evolution of the spine, as well as its pathology, planning of surgical procedures, monitoring its progression and treatment of spinal deformities. The aim of the current study was to revisit the nature of lumbar curve in males and females.Our new automated method uses CT imaging of the spine to measure lumbar curvature in males and females. The curves extracted from 158 individuals were based on the spinal canal, thus avoiding traditional pitfalls of using bone features for curve estimation. The model analysis was carried out on the entire curve, whereby both local and global descriptors were examined in a single framework. Six parameters were calculated: segment length, curve length, curvedness, lordosis peak location, lordosis cranial peak height, and lordosis caudal peak height.Compared to males, the female spine manifested a statistically significant greater curvature, a caudally located lordotic peak, and greater cranial peak height. As caudal peak height is similar for males and females, the illusion of deeper lordosis among females is due partially to the fact that the upper part of the female lumbar curve is positioned more dorsally (more backwardly inclined.Males and females manifest different lumbar curve shape, yet similar amount of inward curving (lordosis. The morphological characteristics of the female spine were probably developed to reduce stress on the vertebral elements during pregnancy and nursing.

  10. The Lumbar Lordosis in Males and Females, Revisited.

    Science.gov (United States)

    Hay, Ori; Dar, Gali; Abbas, Janan; Stein, Dan; May, Hila; Masharawi, Youssef; Peled, Nathan; Hershkovitz, Israel

    2015-01-01

    Whether differences exist in male and female lumbar lordosis has been debated by researchers who are divided as to the nature of variations in the spinal curve, their origin, reasoning, and implications from a morphological, functional and evolutionary perspective. Evaluation of the spinal curvature is constructive in understanding the evolution of the spine, as well as its pathology, planning of surgical procedures, monitoring its progression and treatment of spinal deformities. The aim of the current study was to revisit the nature of lumbar curve in males and females. Our new automated method uses CT imaging of the spine to measure lumbar curvature in males and females. The curves extracted from 158 individuals were based on the spinal canal, thus avoiding traditional pitfalls of using bone features for curve estimation. The model analysis was carried out on the entire curve, whereby both local and global descriptors were examined in a single framework. Six parameters were calculated: segment length, curve length, curvedness, lordosis peak location, lordosis cranial peak height, and lordosis caudal peak height. Compared to males, the female spine manifested a statistically significant greater curvature, a caudally located lordotic peak, and greater cranial peak height. As caudal peak height is similar for males and females, the illusion of deeper lordosis among females is due partially to the fact that the upper part of the female lumbar curve is positioned more dorsally (more backwardly inclined). Males and females manifest different lumbar curve shape, yet similar amount of inward curving (lordosis). The morphological characteristics of the female spine were probably developed to reduce stress on the vertebral elements during pregnancy and nursing.

  11. Impaired visual short-term memory capacity is distinctively associated with structural connectivity of the posterior thalamic radiation and the splenium of the corpus callosum in preterm-born adults.

    Science.gov (United States)

    Menegaux, Aurore; Meng, Chun; Neitzel, Julia; Bäuml, Josef G; Müller, Hermann J; Bartmann, Peter; Wolke, Dieter; Wohlschläger, Afra M; Finke, Kathrin; Sorg, Christian

    2017-04-15

    Preterm birth is associated with an increased risk for lasting changes in both the cortico-thalamic system and attention; however, the link between cortico-thalamic and attention changes is as yet little understood. In preterm newborns, cortico-cortical and cortico-thalamic structural connectivity are distinctively altered, with increased local clustering for cortico-cortical and decreased integrity for cortico-thalamic connectivity. In preterm-born adults, among the various attention functions, visual short-term memory (vSTM) capacity is selectively impaired. We hypothesized distinct associations between vSTM capacity and the structural integrity of cortico-thalamic and cortico-cortical connections, respectively, in preterm-born adults. A whole-report paradigm of briefly presented letter arrays based on the computationally formalized Theory of Visual Attention (TVA) was used to quantify parameter vSTM capacity in 26 preterm- and 21 full-term-born adults. Fractional anisotropy (FA) of posterior thalamic radiations and the splenium of the corpus callosum obtained by diffusion tensor imaging were analyzed by tract-based spatial statistics and used as proxies for cortico-thalamic and cortico-cortical structural connectivity. The relationship between vSTM capacity and cortico-thalamic and cortico-cortical connectivity, respectively, was significantly modified by prematurity. In full-term-born adults, the higher FA in the right posterior thalamic radiation the higher vSTM capacity; in preterm-born adults this FA-vSTM-relationship was inversed. In the splenium, higher FA was correlated with higher vSTM capacity in preterm-born adults, whereas no significant relationship was evident in full-term-born adults. These results indicate distinct associations between cortico-thalamic and cortico-cortical integrity and vSTM capacity in preterm-and full-term-born adults. Data suggest compensatory cortico-cortical fiber re-organization for attention deficits after preterm delivery

  12. Real-space imaging of interfacial water with submolecular resolution

    Science.gov (United States)

    Jiang, Ying; Peking University Team

    2014-03-01

    Water/solid interfaces are vital to our daily lives and also a central theme across an incredibly wide range of scientific disciplines. Resolving the internal structure, i.e. the O-H directionality, of water molecules adsorbed on solid surfaces has been one of the key issues of water science yet remains challenging. Using a low-temperature scanning tunneling microscope (STM), we report the submolecular-resolution imaging of individual water monomers and tetramers on NaCl(001) films supported by a Au(111) substrate at 5 K. The frontier molecular orbitals of adsorbed water were directly visualized, which allowed discriminating the orientation of the monomers and the H-bond directionality of the tetramers in real space. Comparison with ab initio density functional theory calculations reveals that the ability to access the orbital structures of water stems from the electronic decoupling effect provided by the NaCl films and the precisely tunable tip-water coupling. Supported by National Basic Research Programs of China and National Science Foundation of China.

  13. NP-hardness of the cluster minimization problem revisited

    Science.gov (United States)

    Adib, Artur B.

    2005-10-01

    The computational complexity of the 'cluster minimization problem' is revisited (Wille and Vennik 1985 J. Phys. A: Math. Gen. 18 L419). It is argued that the original NP-hardness proof does not apply to pairwise potentials of physical interest, such as those that depend on the geometric distance between the particles. A geometric analogue of the original problem is formulated, and a new proof for such potentials is provided by polynomial time transformation from the independent set problem for unit disk graphs. Limitations of this formulation are pointed out, and new subproblems that bear more direct consequences to the numerical study of clusters are suggested.

  14. NP-hardness of the cluster minimization problem revisited

    International Nuclear Information System (INIS)

    Adib, Artur B

    2005-01-01

    The computational complexity of the 'cluster minimization problem' is revisited (Wille and Vennik 1985 J. Phys. A: Math. Gen. 18 L419). It is argued that the original NP-hardness proof does not apply to pairwise potentials of physical interest, such as those that depend on the geometric distance between the particles. A geometric analogue of the original problem is formulated, and a new proof for such potentials is provided by polynomial time transformation from the independent set problem for unit disk graphs. Limitations of this formulation are pointed out, and new subproblems that bear more direct consequences to the numerical study of clusters are suggested

  15. NP-hardness of the cluster minimization problem revisited

    Energy Technology Data Exchange (ETDEWEB)

    Adib, Artur B [Physics Department, Brown University, Providence, RI 02912 (United States)

    2005-10-07

    The computational complexity of the 'cluster minimization problem' is revisited (Wille and Vennik 1985 J. Phys. A: Math. Gen. 18 L419). It is argued that the original NP-hardness proof does not apply to pairwise potentials of physical interest, such as those that depend on the geometric distance between the particles. A geometric analogue of the original problem is formulated, and a new proof for such potentials is provided by polynomial time transformation from the independent set problem for unit disk graphs. Limitations of this formulation are pointed out, and new subproblems that bear more direct consequences to the numerical study of clusters are suggested.

  16. Rural-Nonrural Disparities in Postsecondary Educational Attainment Revisited

    Science.gov (United States)

    Byun, Soo-yong; Meece, Judith L.; Irvin, Matthew J.

    2013-01-01

    Using data from the National Educational Longitudinal Study, this study revisited rural-nonrural disparities in educational attainment by considering a comprehensive set of factors that constrain and support youth's college enrollment and degree completion. Results showed that rural students were more advantaged in community social resources compared to nonrural students, and these resources were associated with a significant increase in the likelihood of bachelor's degree attainment. Yet results confirmed that rural students lagged behind nonrural students in attaining a bachelor's degree largely due to their lower socioeconomic background. The findings present a more comprehensive picture of the complexity of geographic residence in shaping college enrollment and degree attainment. PMID:24285873

  17. An Improvement on LSB Matching and LSB Matching Revisited Steganography Methods

    OpenAIRE

    Qazanfari, Kazem; Safabakhsh, Reza

    2017-01-01

    The aim of the steganography methods is to communicate securely in a completely undetectable manner. LSB Matching and LSB Matching Revisited steganography methods are two general and esiest methods to achieve this aim. Being secured against first order steganalysis methods is the most important feature of these methods. On the other hand, these methods don't consider inter pixel dependency. Therefore, recently, several steganalysis methods are proposed that by using co-occurrence matrix detec...

  18. Forecasting of Satisfaction and Revisit Intention of Indonesia Shoppers in Shopping Malls

    OpenAIRE

    Ayuni, Risca Fitri

    2017-01-01

    . Due to tight competition, changing value proposition of customer and shiftingof mall functions become center for leisure purposes, shopping mall developer mustfocus on create shopper satisfaction to influence their post-transaction behaviors. Thisstudy investigates the relationship between mall personality, self-congruity, perceivedquality, shopping value, shopper satisfaction and revisit intention. Two hundredrespondents participated in this study. In order to achieve the aim of this study...

  19. Sparse random matrices: The eigenvalue spectrum revisited

    International Nuclear Information System (INIS)

    Semerjian, Guilhem; Cugliandolo, Leticia F.

    2003-08-01

    We revisit the derivation of the density of states of sparse random matrices. We derive a recursion relation that allows one to compute the spectrum of the matrix of incidence for finite trees that determines completely the low concentration limit. Using the iterative scheme introduced by Biroli and Monasson [J. Phys. A 32, L255 (1999)] we find an approximate expression for the density of states expected to hold exactly in the opposite limit of large but finite concentration. The combination of the two methods yields a very simple geometric interpretation of the tails of the spectrum. We test the analytic results with numerical simulations and we suggest an indirect numerical method to explore the tails of the spectrum. (author)

  20. Highway 61 Revisited: Bob Dilan i francuski poststrukturalizam / Highway 61 Revisited: Bob Dilan and French Poststructuralism

    Directory of Open Access Journals (Sweden)

    Nikola Dedić

    2013-06-01

    Full Text Available The main aim of this text is to show parallels between rock music and poststructuralist philosophy. As a case study one of the most celebrated rock albums of all times – Bob Dylan’s Highway 61 Revisited from 1965 is taken. It is one of the crucial albums in the history of popular culture which influenced further development of rock music within American counter culture of the 60s. Dylan’s turn from the politics of American New Left and folk movement, his relation towards the notions of the author and intertextuality, and his connection with experimental usage of language in the manner of avant-garde and neoavant-garde poetry, are juxtaposed with the main philosophical standpoints of Jean-François Lyotard, Jean Baudrillard, Roland Barthes and Julia Kristeva which historically and chronologically coincide with the appearance of Dylan’s album.