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Sample records for author webb dick

  1. What We Talk around when We Talk about "The Dick"

    Science.gov (United States)

    Savage, Elizabeth

    2011-01-01

    Some years ago, the author had her first opportunity to teach an undergraduate American Romanticism course, which meant she had a chance to teach "Moby-Dick" the way she thought it should be taught. Meeting two days a week, her course was set up so that students read about thirty pages of "Moby-Dick" for one class meeting a week paired with…

  2. Thermodynamics of black-holes in Brans-Dicke gravity

    International Nuclear Information System (INIS)

    Kim, H.; Kim, Y.

    1997-01-01

    It is recently been argued that non-trivial Brans-Dicke black-hole solutions different from the usual Schwarzschild solution could exist. The authors attempt here to 'censor' these non-trivial Brans-Dicke black-hole solutions by examining their thermodynamics properties. Quantities like Hawking temperature and entropy of the black holes are computed. The analysis of the behaviors of these thermodynamic quantities appears to show that even in Brans-Dicke gravity, the usual Schwarzschild space-time turns out to be the only physically relevant uncharged black-hole solution

  3. Cosmic no-hair in Brans-Dicke theory

    International Nuclear Information System (INIS)

    Guzman, E.; Alam, S.

    1993-08-01

    In this short note we report our finding that within the context of alternative version of the Brans-Dicke theory (for ω ≥ -3/2, where ω is the Brans-Dicke parameter) the anisotropic Bianchi type cosmological models evolve towards the de Sitter isotropic universe. In short it is shown that during inflation there is no difference between the Brans-Dicke theory and General Relativity. Our result can thus be viewed as a generalization of the Wald's theorem for General Relativity. (author). 5 refs

  4. Remembering Dick Crane

    Science.gov (United States)

    Jossem, E. Leonard

    2007-09-01

    Physicist, polymath, educator, leader, Horace Richard Crane died on April 19, 2007, a few months short of his 100th birthday. Those of us who were fortunate enough to have had him as a friend mourn his loss, but for all of us he leaves a rich and varied legacy of published works that invite reading and rereading. Dick's work as a physicist was recognized in 1966 by his election to the National Academy of Sciences and in 1986 by the award of the President's National Medal of Science: "For the first measurement of the magnetic moment and spin of free electrons and positrons."

  5. Arnott untangles Webb

    International Nuclear Information System (INIS)

    Arnott, Don.

    1989-01-01

    Dr Webb, a former nuclear scientist, reactor physicist and reactor operator now concentrates his efforts on studying the capacity for catastrophic explosions (fires and steam explosions) in PWR type reactors. He gave evidence to the Hinkley Public Inquiry, presenting evidence which analysed the accident hazards of the PWR. This profile shows Dr Webb to be pro-safety rather than anti-reactor. He would support a reactor design which fails safe whatever happens. His talents as a writer and academic are renowned. (U.K.)

  6. Louis Dick (1921 - 2014)

    CERN Multimedia

    2014-01-01

    Louis Dick, a CERN experimental physicist of international renown, passed away on 14 July.   Louis in his office, a veritable archaeological wonder with strata of documents corresponding to various eras of physics. Born in Geneva on 27 April 1921, Louis obtained a physics degree at ETH-Zurich in 1946 before moving to the Institut du Radium in Paris, where he joined the group led by Frédéric and Irène Joliot-Curie. He took a leave of absence in 1957 to go to CERN, where he remained until well beyond his retirement in 1986. In the late 1950s and early 1960s, Louis worked at CERN’s Synchrocyclotron (SC) and later on studies at the Proton Synchrotron (PS). When the first polarised proton target arrived at CERN from Saclay in 1963, Louis proposed using it for studies of spin effects in pion-proton elastic scattering at the PS, and between 1964 and 1966 sizeable spin effects were found. Louis and his collaborators then continued these studies wi...

  7. Lovelock-Brans-Dicke gravity

    Science.gov (United States)

    Wenjie Tian, David; Booth, Ivan

    2016-02-01

    According to Lovelock’s theorem, the Hilbert-Einstein and the Lovelock actions are indistinguishable from their field equations. However, they have different scalar-tensor counterparts, which correspond to the Brans-Dicke and the Lovelock-Brans-Dicke (LBD) gravities, respectively. In this paper the LBD model of alternative gravity with the Lagrangian density {{L}}{LBD}=\\frac{1}{16π }≤ft[φ ≤ft(R+\\frac{a}{\\sqrt{-g}}{}*{RR}+b{ G }\\right)-\\frac{{ω }{{L}}}{φ }{{{\

  8. Nudging van rijsnelheid via Dick Brunaborden : een veldexperiment : de effecten op werkelijk gereden snelheden in vijf gemeenten onderzocht. In opdracht van Metropoolregio Rotterdam Den Haag.

    NARCIS (Netherlands)

    Goldenbeld, C. Groot-Mesken, J. de & Temürhan, M.

    2017-01-01

    Nudging driving speed using Dick Bruna traffic signs: a field experiment; Study of the actual speeds driven in five municipalities in the Netherlands. This report presents the results of a study into the effect of Dick Bruna (Dick Bruna is a Dutch author, illustrator and graphic designer known for

  9. Plane symmetric cosmological model with thick domain walls in Brans-Dicke theory of gravitation

    International Nuclear Information System (INIS)

    Pawar, D.; Bayaskar, S.; Patil, V.

    2009-01-01

    We have investigated plane symmetric cosmological model in presence of thick domain walls in Brans-Dicke theory of gravitation, some geometrical and physical behavior of the model are discussed. (authors)

  10. New Brans-Dicke wormholes

    International Nuclear Information System (INIS)

    He Feng; Kim, Sung-Won

    2002-01-01

    Two new classes of exact solutions in vacuum Brans-Dicke theory are obtained, each of which is a two-way traversable wormhole for the coupling parameter ω<-2 or -2<ω≤0, respectively. Each of the two new classes of exact solutions satisfies not only the general constraints given by Morris and Thorne [Am. J. Phys. 56, 395 (1988)], as concluded earlier, but also the constraints from a trip through a wormhole. It also follows that the scalar field φ plays the role of exotic matter violating the weak energy condition

  11. Renormalization in quantum Brans-Dicke gravity

    OpenAIRE

    Haba, Z.

    2002-01-01

    In the Brans-Dicke model we treat the scalar field exactly and expand the gravitational field in a power series. A comparison with 2D sigma models and \\phi^{4} perturbation theory in four dimensions suggests that the perturbation series in 4D Brans-Dicke model is renormalizable.

  12. The cosmological term and a modified Brans-Dicke cosmology

    International Nuclear Information System (INIS)

    Endo, M.; Fukui, T.

    1977-01-01

    Adding the cosmological term Λ, which is assumed to be variable in this paper, to the Brans-Dicke Lagrangian, an attempt is made to understand the meaning of the term and to relate it to the mass of the universe. The Dirac large-number hypothesis is considered, applying the results obtained from the application of the present theory to a uniform cosmological model. (author)

  13. Fermions in Brans-Dicke cosmology

    International Nuclear Information System (INIS)

    Samojeden, L. L.; Devecchi, F. P.; Kremer, G. M.

    2010-01-01

    Using the Brans-Dicke theory of gravitation we put under investigation a hypothetical universe filled with a fermionic field (with a self-interaction potential) and a matter constituent ruled by a barotropic equation of state. It is shown that the fermionic field [in combination with the Brans-Dicke scalar field φ(t)] could be responsible for a final accelerated era, after an initial matter dominated period.

  14. Thin-shell wormholes in Brans-Dicke gravity

    International Nuclear Information System (INIS)

    Eiroa, Ernesto F.; Richarte, Martin G.; Simeone, Claudio

    2008-01-01

    Spherically symmetric thin-shell wormholes are constructed within the framework of Brans-Dicke gravity. It is shown that, for appropriate values of the Brans-Dicke constant, these wormholes can be supported by matter satisfying the energy conditions

  15. Thin-shell wormholes in Brans-Dicke gravity

    Energy Technology Data Exchange (ETDEWEB)

    Eiroa, Ernesto F. [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pab. I, 1428 Buenos Aires (Argentina); Instituto de Astronomia y Fisica del Espacio, C.C. 67, Suc. 28, 1428 Buenos Aires (Argentina)], E-mail: eiroa@iafe.uba.ar; Richarte, Martin G. [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pab. I, 1428 Buenos Aires (Argentina)], E-mail: martin@df.uba.ar; Simeone, Claudio [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pab. I, 1428 Buenos Aires (Argentina)], E-mail: csimeone@df.uba.ar

    2008-12-22

    Spherically symmetric thin-shell wormholes are constructed within the framework of Brans-Dicke gravity. It is shown that, for appropriate values of the Brans-Dicke constant, these wormholes can be supported by matter satisfying the energy conditions.

  16. The complete Brans–Dicke theories

    International Nuclear Information System (INIS)

    Kofinas, Georgios

    2017-01-01

    Given that the simple wave equation of Brans–Dicke theory for the scalar field is preserved, we have investigated, through exhaustively analyzing the Bianchi identities, the consistent theories which violate the exact energy conservation equation. It is found that only three theories exist which are unambiguously determined from consistency, without imposing arbitrary functions by hand. Each of these theories possesses a specific interaction term which controls the energy exchange between the scalar field and ordinary matter. The theories contain new parameters (integration constants from the integration procedure) and when these are switched-off, Brans–Dicke theory emerges. As usually, the vacuum theories can be defined from the complete Brans–Dicke theories when the matter energy–momentum tensor vanishes.

  17. Overview of the Moby Dick project

    NARCIS (Netherlands)

    Smit, Gerardus Johannes Maria; Havinga, Paul J.M.; Mullender, Sape J.; Helme, A.; Hartvigsen, Gunnar; Fallmyr, Terje; Stabell-Kulo, Tage; Bartoli, Alberto; Dini, Gianluca; Rizzo, Luigi; Avvenuti, Marco; Seppanen, T.

    The Moby Dick project focuses on developing theories, architectures and applications for a new generation of hand-held computers. The combination of an intelligent information system and a location system enables many new types of applications, such as admission control, digital chequebook, paging,

  18. Robert H Dicke – Physicist Extraordinaire

    Indian Academy of Sciences (India)

    Dicke started his college education at the University of Rochester intending to major in engineering. He credits Lee A ... War rumblings were growing louder and Professor DuBridge had left to establish the Radiation ... After the war, he returned to the Department of Physics at Princeton University. He spent the next decade ...

  19. Quantum tunneling in the adiabatic Dicke model

    International Nuclear Information System (INIS)

    Chen Gang; Chen Zidong; Liang Jiuqing

    2007-01-01

    The Dicke model describes N two-level atoms interacting with a single-mode bosonic field and exhibits a second-order phase transition from the normal to the superradiant phase. The energy levels are not degenerate in the normal phase but have degeneracy in the superradiant phase, where quantum tunneling occurs. By means of the Born-Oppenheimer approximation and the instanton method in quantum field theory, the tunneling splitting, inversely proportional to the tunneling rate for the adiabatic Dicke model, in the superradiant phase can be evaluated explicitly. It is shown that the tunneling splitting vanishes as exp(-N) for large N, whereas for small N it disappears as √(N)/exp(N). The dependence of the tunneling splitting on the relevant parameters, especially on the atom-field coupling strength, is also discussed

  20. Qualitative analysis of cosmological models in Brans-Dicke theory, solutions from non-minimal coupling and viscous universe

    International Nuclear Information System (INIS)

    Romero Filho, C.A.

    1988-01-01

    Using dynamical system theory we investigate homogeneous and isotropic models in Brans-Dicke theory for perfect fluids with general equation of state and arbitrary ω. Phase diagrams are drawn on the Poincare sphere which permits a qualitative analysis of the models. Based on this analysis we construct a method for generating classes of solutions in Brans-Dicke theory. The same technique is used for studying models arising from non-minimal coupling of electromagnetism with gravity. In addition, viscous fluids are considered and non-singular solutions with bulk viscosity are found. (author)

  1. False vacuum decay in Jordan-Brans-Dicke cosmologies

    International Nuclear Information System (INIS)

    Holman, R.; Wang, Yun; Weinberg, E.J.

    1989-12-01

    We examine the bubble nucleation rate in a first-order phase transition taking place in a background Jordan-Brans-Dicke cosmology. We compute the leading order terms in the nucleation rate when the Jordan-Brans-Dicke field is large (i.e., late times) by means of a Weyl rescaling of the fields in the theory. We find that despite the fact that the Jordan-Brans-Dicke field (hence the effective gravitational constant) has a time dependence in the false vacuum, at late times the nucleation rate is time independent. 21 refs

  2. Optimized entanglement witnesses for Dicke states

    Energy Technology Data Exchange (ETDEWEB)

    Bergmann, Marcel; Guehne, Otfried [Naturwissenschaftlich-Technische Fakultaet, Universitaet Siegen, Department Physik, Walter-Flex-Strasse 3, D-57068 Siegen (Germany)

    2013-07-01

    Quantum entanglement is an important resource for applications in quantum information processing like quantum teleportation and cryptography. Moreover, the number of particles that can be entangled experimentally using polarized photons or ion traps has been significantly enlarged. Therefore, criteria to decide the question whether a given multi-particle state is entangled or not have to be improved. Our approach to this problem uses the notion of PPT mixtures which form an approximation to the set of bi-separable states. With this method, entanglement witnesses can be obtained in a natural manner via linear semi-definite programming. In our contribution, we will present analytical results for entanglement witnesses for Dicke states. This allows to overcome the limitations of convex optimization.

  3. Cosmological constraints on Brans-Dicke theory.

    Science.gov (United States)

    Avilez, A; Skordis, C

    2014-07-04

    We report strong cosmological constraints on the Brans-Dicke (BD) theory of gravity using cosmic microwave background data from Planck. We consider two types of models. First, the initial condition of the scalar field is fixed to give the same effective gravitational strength Geff today as the one measured on Earth, GN. In this case, the BD parameter ω is constrained to ω>692 at the 99% confidence level, an order of magnitude improvement over previous constraints. In the second type, the initial condition for the scalar is a free parameter leading to a somewhat stronger constraint of ω>890, while Geff is constrained to 0.981theory and are valid for any Horndeski theory, the most general second-order scalar-tensor theory, which approximates the BD theory on cosmological scales. In this sense, our constraints place strong limits on possible modifications of gravity that might explain cosmic acceleration.

  4. Einstein metrics and Brans-Dicke superfields

    International Nuclear Information System (INIS)

    Marques, S.

    1988-01-01

    It is obtained here a space conformal to the Einstein space-time, making the transition from an internal bosonic space, constructed with the Majorana constant spinors in the Majorana representation, to a bosonic ''superspace,'' through the use of Einstein vierbeins. These spaces are related to a Grassmann space constructed with the Majorana spinors referred to above, where the ''metric'' is a function of internal bosonic coordinates. The conformal function is a scale factor in the zone of gravitational radiation. A conformal function dependent on space-time coordinates can be constructed in that region when we introduce Majorana spinors which are functions of those coordinates. With this we obtain a scalar field of Brans-Dicke type. 11 refs

  5. Explaining fast radio bursts through Dicke's superradiance

    Science.gov (United States)

    Houde, Martin; Mathews, Abhilash; Rajabi, Fereshteh

    2018-03-01

    Fast radio bursts (FRBs), characterized by strong bursts of radiation intensity at radio wavelengths lasting on the order of a millisecond, have yet to be firmly associated with a family, or families, of astronomical sources. It follows that despite the large number of proposed models, no well-defined physical process has been identified to explain this phenomenon. In this paper, we demonstrate how Dicke's superradiance, for which evidence has recently been found in the interstellar medium, can account for the characteristics associated with FRBs. Our analysis and modelling of previously detected FRBs suggest they could originate from regions in many ways similar to those known to harbour masers or megamasers, and result from the coherent radiation emanating from populations of molecules associated with large-scale entangled quantum mechanical states. We estimate this entanglement to involve as many as ˜1030 to ˜1032 molecules over distances spanning 100-1000 au.

  6. Analog quantum simulation of generalized Dicke models in trapped ions

    Science.gov (United States)

    Aedo, Ibai; Lamata, Lucas

    2018-04-01

    We propose the analog quantum simulation of generalized Dicke models in trapped ions. By combining bicromatic laser interactions on multiple ions we can generate all regimes of light-matter coupling in these models, where here the light mode is mimicked by a motional mode. We present numerical simulations of the three-qubit Dicke model both in the weak field (WF) regime, where the Jaynes-Cummings behavior arises, and the ultrastrong coupling (USC) regime, where a rotating-wave approximation cannot be considered. We also simulate the two-qubit biased Dicke model in the WF and USC regimes and the two-qubit anisotropic Dicke model in the USC regime and the deep-strong coupling regime. The agreement between the mathematical models and the ion system convinces us that these quantum simulations can be implemented in the laboratory with current or near-future technology. This formalism establishes an avenue for the quantum simulation of many-spin Dicke models in trapped ions.

  7. Interacting ghost dark energy in Brans-Dicke theory

    International Nuclear Information System (INIS)

    Ebrahimi, Esmaeil; Sheykhi, Ahmad

    2011-01-01

    We investigate the QCD ghost model of dark energy in the framework of Brans-Dicke cosmology. First, we study the non-interacting ghost dark energy in a flat Brans-Dicke theory. In this case we obtain the equation of state and the deceleration parameters and a differential equation governing the evolution of ghost energy density. Interestingly enough, we find that the equation of state parameter of the non-interacting ghost dark energy can cross the phantom line (w D =-1) provided the parameters of the model are chosen suitably. Then, we generalize the study to the interacting ghost dark energy in both flat and non-flat Brans-Dicke framework and find out that the transition of w D to phantom regime can be more easily achieved for than when resort to the Einstein field equations is made.

  8. Inflation and dark energy from the Brans-Dicke theory

    Energy Technology Data Exchange (ETDEWEB)

    Artymowski, Michał [Institute of Physics, Jagiellonian UniversityŁojasiewicza 11, 30-348 Kraków (Poland); Lalak, Zygmunt; Lewicki, Marek [Institute of Theoretical Physics, Faculty of Physics, University of Warsawul. Pasteura 5, 02-093 Warszawa (Poland)

    2015-06-17

    We consider the Brans-Dicke theory motivated by the f(R)=R+αR{sup n}−βR{sup 2−n} model to obtain a stable minimum of the Einstein frame scalar potential of the Brans-Dicke field. As a result we have obtained an inflationary scalar potential with non-zero value of residual vacuum energy, which may be a source of dark energy. In addition we discuss the probability of quantum tunnelling from the minimum of the potential. Our results can be easily consistent with PLANCK or BICEP2 data for appropriate choices of the value of n and ω.

  9. Majumdar-Papapetrou class of nonstatic cylindrically symmetric Brans-Dicke-Maxwell fields

    International Nuclear Information System (INIS)

    Tiwari, R.N.; Rao, P.P.

    1979-01-01

    Relations have been obtained between certain components of the metric and the electromagnetic potentials for source-free Brans-Dicke-Maxwell fields described by a nonstatic cylindrically symmetric Einstein-Rosen metric. These are important, in the sense that they generate a class of solutions that in a way can be said to belong to the class generated by similar relations obtained by Majumdar (Phys. Rev.; 72: 390 (1947)) and Papapetrou (Proc. R. Ir. Acad. Sect. A.; 51: 191 (1947)) for generalized static Einstein-Maxwell fields. The relations have further been used to reduce the B-D Maxwell equations to B-D vacuum equations and vice versa. (author)

  10. An extended geometric criterion for chaos in the Dicke model

    International Nuclear Information System (INIS)

    Li Jiangdan; Zhang Suying

    2010-01-01

    We extend HBLSL's (Horwitz, Ben Zion, Lewkowicz, Schiffer and Levitan) new Riemannian geometric criterion for chaotic motion to Hamiltonian systems of weak coupling of potential and momenta by defining the 'mean unstable ratio'. We discuss the Dicke model of an unstable Hamiltonian system in detail and show that our results are in good agreement with that of the computation of Lyapunov characteristic exponents.

  11. Non-static local string in Brans–Dicke theory

    Indian Academy of Sciences (India)

    Abstract. A recent investigation showed that a local gauge string with a phenomenological energy momentum tensor, as prescribed by Vilenkin, is inconsistent in Brans–Dicke theory. In this work it has been shown that such a string is indeed consistent if one introduces time dependences in the metric. A set of solutions of full ...

  12. Higher dimensional global monopole in Brans–Dicke theory

    Indian Academy of Sciences (India)

    Keywords. Global monopole; Brans–Dicke theory; higher dimension. PACS Nos 04.20.Jb; 98.80.Bp; 04.50.+h. 1. Introduction. The idea of higher dimensional theory was originated in super string and super gravity the- ories to unify gravity with other fundamental forces in nature. Solutions of Einstein field equations in higher ...

  13. Interview with Marcel Dicke: the Droste effect in science

    NARCIS (Netherlands)

    Dicke, M.

    2015-01-01

    Marcel Dicke grew up at the outskirts of Rotterdam, The Netherlands. He enjoyed strolling through the meadows and jumping over ditches to observe animals and plants. He was interested in life in general and his interest in biology, and especially ecology, was aroused by his inspiring high school

  14. Minimizing energy consumption for wireless computers in Moby Dick

    NARCIS (Netherlands)

    Havinga, Paul J.M.; Smit, Gerardus Johannes Maria

    1997-01-01

    The Moby Dick project is a joint European project to develop and define the architecture of a new generation of mobile hand-held computers, called Pocket Companions. The Pocket Companion is a hand-held device that is resource-poor, i.e. small amount of memory, limited battery life, low processing

  15. Transactions en eaux troubles : résurgences de la voix shakespearienne dans Moby-Dick Defamiliarising the Bard: The Resurgence of Shakespeare in Moby-Dick

    Directory of Open Access Journals (Sweden)

    Ronan Ludot-Vlasak

    2009-06-01

    Full Text Available This article explores the way Herman Melville appropriates William Shakespeare’s work in Moby-Dick. Its argument is that by defamiliarising some of Shakespeare’s lines—a corpus that was both alien and familiar to nineteenth-century writers— Melville turns them into his own idiom. This resurgence of the Shakespearean voice is double: although the dramatic element in the novel is often associated with the figure of Ahab, Ishmael also incorporates Shakespearean lines into his narrative. What characterises these (intertextual transactions is that instead of quoting directly from Shakespeare’s plays, Melville often blurs references in order to appropriate the works of his predecessor. More than the mere imitation of a model, this complex process reveals Shakespeare’s seminal role in Moby-Dick as well as Melville’s poetics of reinvention. Ultimately, it enables the author to explore the dark forces lying beneath the surface of things.

  16. Interacting holographic dark energy in Brans-Dicke theory

    International Nuclear Information System (INIS)

    Sheykhi, Ahmad

    2009-01-01

    We study cosmological application of interacting holographic energy density in the framework of Brans-Dicke cosmology. We obtain the equation of state and the deceleration parameter of the holographic dark energy in a non-flat universe. As system's IR cutoff we choose the radius of the event horizon measured on the sphere of the horizon, defined as L=ar(t). We find that the combination of Brans-Dicke field and holographic dark energy can accommodate w D =-1 crossing for the equation of state of noninteracting holographic dark energy. When an interaction between dark energy and dark matter is taken into account, the transition of w D to phantom regime can be more easily accounted for than when resort to the Einstein field equations is made.

  17. Stability of Brans-Dicke thin-shell wormholes

    Energy Technology Data Exchange (ETDEWEB)

    Yue, Xiaojun, E-mail: yuexiaojun@mail.bnu.edu.cn [Department of Physics, Beijing Normal University, Beijing 100875 (China); Gao, Sijie, E-mail: sijie@bnu.edu.cn [Department of Physics, Beijing Normal University, Beijing 100875 (China)

    2011-06-06

    Recently, a class of spherically symmetric thin-shell wormholes in Brans-Dicke gravity have been introduced. Such wormholes can be supported by matter satisfying the weak energy condition (WEC). In this Letter, we first obtain all the exact solutions satisfying the WEC. Then we show these solutions can be stable for certain parameters. A general requirement for stability is that β{sup 2}>1, which may imply that the speed of sound exceeds the speed of light. -- Highlights: → Brans-Dicke thin-shell wormholes can be stable and satisfy the energy condition. → Solutions exist for ω<-2. → The speed of sound in the matter exceeds the speed of light.

  18. Unified dark fluid in Brans-Dicke theory

    International Nuclear Information System (INIS)

    Tripathy, Sunil K.; Behera, Dipanjali; Mishra, Bivudutta

    2015-01-01

    Anisotropic dark energy cosmological models are constructed in the frame work of generalised Brans-Dicke theory with a self-interacting potential. A unified dark fluid characterised by a linear equation of state is considered as the source of dark energy. The shear scalar is considered to be proportional to the expansion scalar simulating an anisotropic relationship among the directional expansion rates. The dynamics of the universe in the presence of a unified dark fluid in anisotropic background have been discussed. The presence of an evolving scalar field makes it possible to get an accelerating phase of expansion even for a linear relationship among the directional Hubble rates. It is found that the anisotropy in expansion rates does not affect the scalar field, the self-interacting potential, but it controls the non-evolving part of the Brans-Dicke parameter. (orig.)

  19. Dicke-model simulation via cavity-assisted Raman transitions

    Science.gov (United States)

    Zhang, Zhiqiang; Lee, Chern Hui; Kumar, Ravi; Arnold, K. J.; Masson, Stuart J.; Grimsmo, A. L.; Parkins, A. S.; Barrett, M. D.

    2018-04-01

    The Dicke model is of fundamental importance in quantum mechanics for understanding the collective behavior of atoms coupled to a single electromagnetic mode. Here, we demonstrate a Dicke-model simulation via cavity-assisted Raman transitions in a configuration using counterpropagating laser beams. The observations indicate that motional effects should be included to fully account for the results. These results are contrary to experiments using single-beam and copropagating configurations. We give a theoretical description that accounts for the beam geometries used in the experiments and indicates the potential role of motional effects. In particular, a model is given that highlights the influence of Doppler broadening on the observed phase-transition thresholds.

  20. Inflation and dark energy from the Brans-Dicke theory

    Energy Technology Data Exchange (ETDEWEB)

    Artymowski, Michał [Institute of Physics, Jagiellonian University Łojasiewicza 11, 30-348 Kraków (Poland); Lalak, Zygmunt; Lewicki, Marek, E-mail: Michal.Artymowski@uj.edu.pl, E-mail: Zygmunt.Lalak@fuw.edu.pl, E-mail: Marek.Lewicki@fuw.edu.pl [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw ul. Pasteura 5, 02-093 Warszawa (Poland)

    2015-06-01

    We consider the Brans-Dicke theory motivated by the f(R) = R + α R{sup n} − β R{sup 2−n} model to obtain a stable minimum of the Einstein frame scalar potential of the Brans-Dicke field. As a result we have obtained an inflationary scalar potential with non-zero value of residual vacuum energy, which may be a source of dark energy. In addition we discuss the probability of quantum tunnelling from the minimum of the potential. Our results can be easily consistent with PLANCK or BICEP2 data for appropriate choices of the value of n and ω.

  1. Charles Dick: Agricultural Regulation in Santa Cruz, 1930- 1967

    OpenAIRE

    Regional History Project, UCSC Library; Dick, Charles; Jarrell, Randall

    1997-01-01

    This is the oral history of the late county agricultural commissioner, who traces the history of California's unique system of agricultural regulation and inspection, which dates from the 1880s. Dick's overview of county agriculture includes the increasing importance of pesticide regulation (which is currently a very debated issue in the strawberry industry); mechanization, changes in local crops and acreages, farm labor and unionization, and the demise of the family farm.

  2. Antigravity in F( R) and Brans-Dicke theories

    Science.gov (United States)

    Oikonomou, V. K.; Karagiannakis, N.

    2014-12-01

    We study antigravity in F( R)-theory originating scalar-tensor theories and also in Brans-Dicke models without cosmological constant. For the F( R) theory case, we obtain the Jordan frame antigravity scalar-tensor theory by using a variant of the Lagrange multipliers method and we numerically study the time dependent effective gravitational constant. As we shall demonstrate in detail by using some viable F( R) models, although the initial F( R) models have no antigravity, their scalar-tensor counterpart theories might or not have antigravity, a fact mainly depending on the parameter that characterizes antigravity. Similar results hold true in the Brans-Dicke model, which we also studied numerically. In addition, regarding the Brans-Dicke model we also found some analytic cosmological solutions. Since antigravity is an unwanted feature in gravitational theories, our findings suggest that in the case of F( R) theories, antigravity does not occur in the real world described by the F( R) theory, but might occur in the Jordan frame scalar-tensor counterpart of the F( R) theory, and this happens under certain circumstances. The central goal of our study is to present all different cases in which antigravity might occur in modified gravity models.

  3. Obituary: Richard L. (Dick) Walker, Jr., 1938-2005

    Science.gov (United States)

    Pier, Jeffrey R.; Mason, Brian

    2005-12-01

    Dick Walker, 67, died 30 March 2005 in Flagstaff, AZ, following a long illness. He was born on 9 March 1938 in Hampton, Iowa and grew up in Waterloo, Iowa. As a child, Dick was fascinated with astronomy and built his own telescope. He saved his pennies and bought and read every book on the subject he could find. He also raised pigeons, naming four of them Hertzsprung, Hoyle, Gamow, and Kron. In 1957, the year Sputnik was launched, Dick began his college studies at the University of Northern Iowa in Cedar Falls. In 1959, he transferred to the State University of Iowa (subsequently renamed the University of Iowa) in Iowa City, where he earned a BA degree in astronomy and physics in 1963. He joined the staff of the U.S. Naval Observatory in Washington, DC, where he worked in the Time Service Division for a year before his assignment to the Astrometry and Astrophysics Division. Dick relocated to Flagstaff, AZ, in 1966 to continue his Naval Observatory service at the Flagstaff Station. His retirement in May 1999, ended a thirty-six-year career with USNO. Dick was first and foremost an observational astronomer. From the mid 1960s through the late 1970s, much of Dick's time was devoted to the measurement of binary stars, observing with the 12-inch and 26-inch refractors in Washington and later the 40-inch and 61-inch reflectors in Flagstaff. He also made many trips to Lick Observatory to work with the 36-inch Clark Refractor there. During this time he consulted with Charles Worley, who was observing on the 26-inch, to make sure time was well-spent examining doubles that could not be observed in Washington. This period of observing overlapped with the early years of speckle interferometry, and Dick's observations, made with the largest telescope used for micrometry at the time, were very important for ascertaining the veracity of this new technique. He was a studious and very careful observer of doubles and made over 8,000 measures, resulting in almost 3,000 mean positions

  4. NASA 3D Models: James Webb Space Telescope

    Data.gov (United States)

    National Aeronautics and Space Administration — The James Webb Space Telescope (JWST) will be a large infrared telescope with a 6.5-meter primary mirror. The project is working to a 2018 launch date. The JWST will...

  5. Dicke phase transition with multiple superradiant states in quantum chaotic resonators

    KAUST Repository

    Liu, C.; Di, Falco, A.; Fratalocchi, Andrea

    2014-01-01

    We experimentally investigate the Dicke phase transition in chaotic optical resonators realized with two-dimensional photonics crystals. This setup circumvents the constraints of the system originally investigated by Dicke and allows a detailed study of the various properties of the superradiant transition. Our experimental results, analytical prediction, and numerical modeling based on random-matrix theory demonstrate that the probability density P? of the resonance widths provides a new criterion to test the occurrence of the Dicke transition.

  6. Dicke phase transition with multiple superradiant states in quantum chaotic resonators

    KAUST Repository

    Liu, C.

    2014-06-12

    We experimentally investigate the Dicke phase transition in chaotic optical resonators realized with two-dimensional photonics crystals. This setup circumvents the constraints of the system originally investigated by Dicke and allows a detailed study of the various properties of the superradiant transition. Our experimental results, analytical prediction, and numerical modeling based on random-matrix theory demonstrate that the probability density P? of the resonance widths provides a new criterion to test the occurrence of the Dicke transition.

  7. The James Webb Space Telescope Mission

    Science.gov (United States)

    Sonneborn, George

    2010-01-01

    The James Webb Space Telescope (JWST) is a large aperture, cryogenic, infrared-optimized space observatory under development by NASA for launch in 2014. The European and Canadian Space Agencies are mission partners. JWST will find and study the first galaxies that formed in the early universe, peer through dusty clouds to see AGN environments and stars forming planetary systems at high spatial resolution. The breakthrough capabilities of JWST will enable new studies of star formation and evolution in the Milky Way, including the Galactic Center, nearby galaxies, and the early universe. JWST's instruments are designed to work primarily in the infrared range of 1 - 28 microns, with some capability in the visible. JWST will have a segmented primary mirror, approximately 6.5 meters in diameter, and will be diffraction-limited at wavelength of 2 microns (0.1 arcsec resolution). The JWST observatory will be placed in a L2 orbit by an Ariane 5 launch vehicle provided by ESA. The observatory is designed for a 5-year prime science mission, with propellant for 10 years of science operations. The instruments will provide broad- and narrow-band imaging, coronography, and multi-object and integral-field spectroscopy (spectral resolution of 100 to 3,000) across the 1 - 28 micron wavelength range. Science and mission operations will be conducted from the Space Telescope Science Institute in Baltimore, Maryland.

  8. The "Very Cool" James Webb Space Telescope!

    Science.gov (United States)

    Teague, Peter J. B.

    2018-01-01

    For over twenty years, scientists, engineers, technicians, and other personnel have been working on the next generation space telescope. As a partnership between NASA (National Aeronautics and Space Administration), CSA (Canadian Space Agency), and ESA (European Space Angency), the James Webb Space Telescope will complement the previous research performed by the Hubble by utilizing a larger primary mirror, which will also be optimized for infrared wavelengths. This combination will allow JWST to collect data and take images of light having traveled over 13.7 billion light years. This presentation will focus on the mission, as well as the contamination control challenges during the integration and testing in the NASA Goddard Spacecraft Systems Development and Integration Facility (SSDIF), one of the largest cleanrooms in the world. Additional information will be presented regarding space simulation testing down to a cool 20 degrees Kelvin [-424 degrees Fahrenheit] that will occur at Johnson Space Center in Houston, TX, and more testing and integration to happen at Northrop Grumman Corp., in Redondo Beach, CA. Launch of the JWST is currently scheduled for the spring of 2019 at Ariane Spaceport in French Guiana, South America.

  9. Interacting HDE and NADE in Brans-Dicke chameleon cosmology

    International Nuclear Information System (INIS)

    Sheykhi, Ahmad; Jamil, Mubasher

    2011-01-01

    Motivated by the recent work of one of us Setare and Jamil (2010) , we generalize this work to the case where the pressureless dark matter and the holographic dark energy do not conserve separately but interact with each other. We investigate the cosmological applications of interacting holographic dark energy in Brans-Dicke theory with chameleon scalar field which is non-minimally coupled to the matter field. We find out that in this model the phantom crossing can be constructed if the model parameters are chosen suitably. We also perform the study for the new agegraphic dark energy model and calculate some relevant cosmological parameters and their evolution.

  10. Interacting HDE and NADE in Brans-Dicke chameleon cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Sheykhi, Ahmad, E-mail: sheykhi@mail.uk.ac.i [Department of Physics, Shahid Bahonar University, P.O. Box 76175, Kerman (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Jamil, Mubasher, E-mail: mjamil@camp.nust.edu.p [Center for Advanced Mathematics and Physics, National University of Sciences and Technology, H-12, Islamabad (Pakistan)

    2011-01-03

    Motivated by the recent work of one of us Setare and Jamil (2010) , we generalize this work to the case where the pressureless dark matter and the holographic dark energy do not conserve separately but interact with each other. We investigate the cosmological applications of interacting holographic dark energy in Brans-Dicke theory with chameleon scalar field which is non-minimally coupled to the matter field. We find out that in this model the phantom crossing can be constructed if the model parameters are chosen suitably. We also perform the study for the new agegraphic dark energy model and calculate some relevant cosmological parameters and their evolution.

  11. Straight spinning cosmic strings in Brans-Dicke gravity

    Science.gov (United States)

    Dos Santos, S. Mittmann; da Silva, J. M. Hoff; Cindra, J. L.

    2018-03-01

    An exact solution of straight spinning cosmic strings in Brans-Dicke theory of gravitation is presented. The possibility of the existence of closed time-like curves around these cosmic strings is analyzed. Furthermore, the stability about the formation of the topological defect discussed here is checked. It is shown that the existence of a suitable choice for the integration constants in which closed time-like curves are not allowed. We also study the (im)possibility of using the obtained spacetime in the rotational curves problem.

  12. Thermodynamics in modified Brans-Dicke gravity with entropy corrections

    Energy Technology Data Exchange (ETDEWEB)

    Rani, Shamaila; Jawad, Abdul; Nawaz, Tanzeela [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan); Manzoor, Rubab [University of Management and Technology, Department of Mathematics, Lahore (Pakistan)

    2018-01-15

    In this paper, we investigate the thermodynamics in the frame-work of recently proposed theory called modified Brans-Dicke gravity (Kofinas et al. in Class Quantum Gravity 33:15, 2016). For this purpose, we develop the generalized second law of thermodynamics by assuming usual entropy as well as its corrected forms (logarithmic and power law corrected) on the apparent and event horizons. In order to analyzed the clear view of thermodynamic law, the power law forms of scalar field and scale factor is being assumed. We evaluate the results graphically and found that generalized second law of thermodynamics holds in most of the cases. (orig.)

  13. Thermodynamics in modified Brans-Dicke gravity with entropy corrections

    International Nuclear Information System (INIS)

    Rani, Shamaila; Jawad, Abdul; Nawaz, Tanzeela; Manzoor, Rubab

    2018-01-01

    In this paper, we investigate the thermodynamics in the frame-work of recently proposed theory called modified Brans-Dicke gravity (Kofinas et al. in Class Quantum Gravity 33:15, 2016). For this purpose, we develop the generalized second law of thermodynamics by assuming usual entropy as well as its corrected forms (logarithmic and power law corrected) on the apparent and event horizons. In order to analyzed the clear view of thermodynamic law, the power law forms of scalar field and scale factor is being assumed. We evaluate the results graphically and found that generalized second law of thermodynamics holds in most of the cases. (orig.)

  14. On the action of the complete Brans-Dicke theory

    Energy Technology Data Exchange (ETDEWEB)

    Kofinas, Georgios [University of the Aegean, Research Group of Geometry, Dynamical Systems and Cosmology, Department of Information and Communication Systems Engineering, Karlovassi, Samos (Greece); Tsoukalas, Minas [Bogazici University, Physics Department, Istanbul (Turkey); National Technical University of Athens, Physics Division, Athens (Greece)

    2016-12-15

    Recently the most general completion of Brans-Dicke theory has appeared with energy exchanged between the scalar field and ordinary matter, given that the equation of motion for the scalar field keeps the simple wave form of Brans-Dicke. This class of theories contain undetermined functions, but there exist only three theories which are unambiguously determined from consistency. Here, for the first such theory, the action of the vacuum theory is found, which arises as the limit of the full matter theory. A symmetry transformation of this vacuum action in the Jordan frame is found which consists of a conformal transformation of the metric together with a redefinition of the scalar field. Since the general family of vacuum theories is parametrized by an arbitrary function of the scalar field, the action of this family is also found. As for the full theory with matter the action of the system is only found when the matter Lagrangian vanishes on-shell, as for example for pressureless dust. Due to the interaction, the matter Lagrangian is non-minimally coupled either in the Jordan or the Einstein frame. (orig.)

  15. On the action of the complete Brans-Dicke theory

    International Nuclear Information System (INIS)

    Kofinas, Georgios; Tsoukalas, Minas

    2016-01-01

    Recently the most general completion of Brans-Dicke theory has appeared with energy exchanged between the scalar field and ordinary matter, given that the equation of motion for the scalar field keeps the simple wave form of Brans-Dicke. This class of theories contain undetermined functions, but there exist only three theories which are unambiguously determined from consistency. Here, for the first such theory, the action of the vacuum theory is found, which arises as the limit of the full matter theory. A symmetry transformation of this vacuum action in the Jordan frame is found which consists of a conformal transformation of the metric together with a redefinition of the scalar field. Since the general family of vacuum theories is parametrized by an arbitrary function of the scalar field, the action of this family is also found. As for the full theory with matter the action of the system is only found when the matter Lagrangian vanishes on-shell, as for example for pressureless dust. Due to the interaction, the matter Lagrangian is non-minimally coupled either in the Jordan or the Einstein frame. (orig.)

  16. Weaving a Webb story: Communicating Science for JWST

    Science.gov (United States)

    Lockwood, Alexandra

    2018-01-01

    NASA’s next great observatory is an impressive and complex mission with many tales to tell. Science is a collection of stories and Webb will be a storytelling machine. How are we preparing to share the scientific news to come from this amazing telescope? From news releases to multimedia content to a vast online presence, the stories of the James Webb Space Telescope will require crafting in order to impact the widest audience. We discuss the art of storytelling based on messaging, goals, mediums, and audience, and how you can apply the same principles to communicating your own research.

  17. A Scientific Revolution: The Hubble and James Webb Space Telescopes

    Science.gov (United States)

    Gardner, Jonathan P.

    2010-01-01

    Astronomy is going through a scientific revolution, responding to a flood of data from the Hubble Space Telescope, other space missions, and large telescopes on the ground. In this talk, I will discuss some of the important discoveries of the last decade, from dwarf planets in the outer Solar System to the mysterious dark energy that overcomes gravity to accelerate the expansion of the Universe. The next decade will be equally bright with the newly refurbished Hubble and the promise of its successor, the James Webb Space Telescope. An infrared-optimized 6.5m space telescope, Webb is designed to find the first galaxies that formed in the early universe and to peer into the dusty gas clouds where stars and planets are born. With MEMS technology, a deployed primary mirror and a tennis-court sized sunshield, the mission presents many technical challenges. I will describe Webb's scientific goals, its design and recent progress in constructing the observatory. Webb is scheduled for launch in 2014.

  18. Decoherence, entanglement, and chaos in the Dicke model

    International Nuclear Information System (INIS)

    Hou Xiwen; Hu Bambi

    2004-01-01

    The dynamical properties of quantum entanglement in the Dicke model without rotating-wave approximation are investigated in terms of the reduced-density linear entropy. The characteristic time of decoherence process in the early-time evolution is numerically obtained and it is shown that the characteristic time decreases as the coupling parameter increases. The mean entanglement, which is defined to be averaged over time, is employed to describe the influences of both quantum phase transition and corresponding classical chaos on the behavior of entanglement. For a given energy, initial conditions are taken to be minimum uncertainty wave packets centered at regular and chaotic regions of the classical phase space. It is shown that the entanglement has a distinct change at the quantum phase transition, and that the entanglement for regular initial conditions is smaller than that for chaotic ones in the case of weak coupling, while it fluctuates with small amplitude in strong coupling and for chaotic initial conditions

  19. Naked singularity formation in Brans-Dicke theory

    Energy Technology Data Exchange (ETDEWEB)

    Ziaie, Amir Hadi; Atazadeh, Khedmat [Department of Physics, Shahid Beheshti University, Evin, Tehran 19839 (Iran, Islamic Republic of); Tavakoli, Yaser, E-mail: am.ziaie@mail.sbu.ac.i, E-mail: k-atazadeh@sbu.ac.i, E-mail: tavakoli@ubi.p [Departamento de Fisica, Universidade da Beira Interior, Rua Marques d' Avila e Bolama, 6200 Covilha (Portugal)

    2010-04-07

    Gravitational collapse of the Brans-Dicke scalar field with non-zero potential in the presence of matter fluid obeying the barotropic equation of state, p = wrho, is studied. Utilizing the concept of the expansion parameter, it is seen that the cosmic censorship conjecture may be violated for w=-1/3 and w=-2/3 which correspond to the cosmic string and domain wall, respectively. We have shown that physically, it is the rate of collapse that governs the formation of a black hole or a naked singularity as the final fate of dynamical evolution and only for these two cases can the singularity be naked as the collapse end state. Also the weak energy condition is satisfied by the collapsing configuration.

  20. Motional frequency shifts of trapped ions in the Lamb-Dicke regime

    International Nuclear Information System (INIS)

    Lizuain, I.; Muga, J. G.; Eschner, J.

    2007-01-01

    First order Doppler effects are usually ignored in laser driven trapped ions when the recoil frequency is much smaller than the trapping frequency (Lamb-Dicke regime). This means that the central, carrier excitation band is supposed to be unaffected by vibronic transitions in which the vibrational number changes. While this is strictly true in the Lamb-Dicke limit (infinitely tight confinement), the vibronic transitions do play a role in the Lamb-Dicke regime. In this paper we quantify the asymptotic behavior of their effect with respect to the Lamb-Dicke parameter. In particular, we give analytical expressions for the frequency shift, 'pulling' or 'pushing', produced in the carrier absorption band by the vibronic transitions both for Rabi and Ramsey schemes. This shift is shown to be independent of the initial vibrational state

  1. Evolution of the Brans—Dicke Parameter in Generalized Chameleon Cosmology

    International Nuclear Information System (INIS)

    Jamil, Mubasher; Momeni, D.

    2011-01-01

    Motivated by an earlier study of Sahoo and Singh [Mod. Phys. Lett. A 17 (2002) 2409], we investigate the time dependence of the Brans-Dicke parameter ω(t) for an expanding Universe in the generalized Brans-Dicke Chameleon cosmology, and obtain an explicit dependence of ω(t) in different expansion phases of the Universe. Also, we discuss how the observed accelerated expansion of the observable Universe can be accommodated in the present formalism. (geophysics, astronomy, and astrophysics)

  2. Responses of the Brans-Dicke field due to gravitational collapses

    International Nuclear Information System (INIS)

    Hwang, Dong-il; Yeom, Dong-han

    2010-01-01

    We study responses of the Brans-Dicke field due to gravitational collapses of scalar field pulses using numerical simulations. Double-null formalism is employed to implement the numerical simulations. If we supply a scalar field pulse, it will asymptotically form a black hole via dynamical interactions of the Brans-Dicke field. Hence, we can observe the responses of the Brans-Dicke field by two different regions. First, we observe the late time behaviors after the gravitational collapse, which include formations of a singularity and an apparent horizon. Second, we observe the fully dynamical behaviors during the gravitational collapse and view the energy-momentum tensor components. For the late time behaviors, if the Brans-Dicke coupling is greater (or smaller) than -1.5, the Brans-Dicke field decreases (or increases) during the gravitational collapse. Since the Brans-Dicke field should be relaxed to the asymptotic value with the elapse of time, the final apparent horizon becomes time-like (or space-like). For the dynamical behaviors, we observed the energy-momentum tensors around ω ∼ -1.5. If the Brans-Dicke coupling is greater than -1.5, the T uu component can be negative at the outside of the black hole. This can allow an instantaneous inflating region during the gravitational collapse. If the Brans-Dicke coupling is less than -1.5, the oscillation of the T vv component allows the apparent horizon to shrink. This allows a combination that violates weak cosmic censorship. Finally, we discuss the implications of the violation of the null energy condition and weak cosmic censorship.

  3. Responses of the Brans-Dicke field due to gravitational collapses

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Dong-il; Yeom, Dong-han, E-mail: enotsae@gmail.co, E-mail: innocent@muon.kaist.ac.k [Department of Physics, KAIST, Daejeon 305-701 (Korea, Republic of)

    2010-10-21

    We study responses of the Brans-Dicke field due to gravitational collapses of scalar field pulses using numerical simulations. Double-null formalism is employed to implement the numerical simulations. If we supply a scalar field pulse, it will asymptotically form a black hole via dynamical interactions of the Brans-Dicke field. Hence, we can observe the responses of the Brans-Dicke field by two different regions. First, we observe the late time behaviors after the gravitational collapse, which include formations of a singularity and an apparent horizon. Second, we observe the fully dynamical behaviors during the gravitational collapse and view the energy-momentum tensor components. For the late time behaviors, if the Brans-Dicke coupling is greater (or smaller) than -1.5, the Brans-Dicke field decreases (or increases) during the gravitational collapse. Since the Brans-Dicke field should be relaxed to the asymptotic value with the elapse of time, the final apparent horizon becomes time-like (or space-like). For the dynamical behaviors, we observed the energy-momentum tensors around {omega} {approx} -1.5. If the Brans-Dicke coupling is greater than -1.5, the T{sub uu} component can be negative at the outside of the black hole. This can allow an instantaneous inflating region during the gravitational collapse. If the Brans-Dicke coupling is less than -1.5, the oscillation of the T{sub vv} component allows the apparent horizon to shrink. This allows a combination that violates weak cosmic censorship. Finally, we discuss the implications of the violation of the null energy condition and weak cosmic censorship.

  4. Experimental violation of the local realism for four-qubit Dicke state.

    Science.gov (United States)

    Zhao, Yuan-Yuan; Wu, Yu-Chun; Xiang, Guo-Yong; Li, Chuan-Feng; Guo, Guang-Can

    2015-11-16

    Dicke state is an widely used type of multi-particle entangled state in quantum information. However, very few works have been done on its nonlocality. Here we prepare a four-photon symmetric Dicke state, whose fidelity is as high as 0.904 ± 0.004, and devise a simple Bell-type inequality to demonstrate that it violates the local realism with 12 standard deviation.

  5. Solar System Observations with the James Webb Space Telescope

    OpenAIRE

    Norwood, James; Hammel, Heidi; Milam, Stefanie; Stansberry, John; Lunine, Jonathan; Chanover, Nancy; Hines, Dean; Sonneborn, George; Tiscareno, Matthew; Brown, Michael; Ferruit, Pierre

    2014-01-01

    The James Webb Space Telescope will enable a wealth of new scientific investigations in the near- and mid-infrared, with sensitivity and spatial/spectral resolution greatly surpassing its predecessors. In this paper, we focus upon Solar System science facilitated by JWST, discussing the most current information available concerning JWST instrument properties and observing techniques relevant to planetary science. We also present numerous example observing scenarios for a wide variety of Solar...

  6. The Critical Point Entanglement and Chaos in the Dicke Model

    Directory of Open Access Journals (Sweden)

    Lina Bao

    2015-07-01

    Full Text Available Ground state properties and level statistics of the Dicke model for a finite number of atoms are investigated based on a progressive diagonalization scheme (PDS. Particle number statistics, the entanglement measure and the Shannon information entropy at the resonance point in cases with a finite number of atoms as functions of the coupling parameter are calculated. It is shown that the entanglement measure defined in terms of the normalized von Neumann entropy of the reduced density matrix of the atoms reaches its maximum value at the critical point of the quantum phase transition where the system is most chaotic. Noticeable change in the Shannon information entropy near or at the critical point of the quantum phase transition is also observed. In addition, the quantum phase transition may be observed not only in the ground state mean photon number and the ground state atomic inversion as shown previously, but also in fluctuations of these two quantities in the ground state, especially in the atomic inversion fluctuation.

  7. WWER440 few group data library preparation and its application in MOBY-DICK modular system

    International Nuclear Information System (INIS)

    Krysl, V.; Mikolas, P.; Svarny, J.

    2002-01-01

    Paper provides summary of methodology of few-group library preparation with emphasis on new features of assemblies, like fuel assemblies with Gd burnable poison or Control Fuel Assembly with Hf plates. Special attention is devoted to the transient part (coupler) of Control Fuel Assembly from the point of view of boundary conditions preparation. Based of this methodology prepared library is implemented into macro code for different number of axial meshes for both coarse and fine mesh diffusion calculations. Problems with local power peaking calculations in WWER-440 cores are closely connected with the correct modeling of the power perturbations in the neighbourhood of Control Fuel Assembly coupler. The new version of MOBY-DICK provided with the new few group data library can assess most of effects induced by insertion of Control Fuel Assembly in the core including effects of newly designed Hf plates in the coupler of Control Fuel Assembly. Compatibility of transport and diffusion calculation was taken into account in the analysis of Control Fuel Assembly movement without/with Hf plates (Authors)

  8. Non-singular Brans–Dicke collapse in deformed phase space

    Energy Technology Data Exchange (ETDEWEB)

    Rasouli, S.M.M., E-mail: mrasouli@ubi.pt [Departamento de Física, Universidade da Beira Interior, Rua Marquês d’Avila e Bolama, 6200 Covilhã (Portugal); Centro de Matemática e Aplicações (CMA - UBI), Universidade da Beira Interior, Rua Marquês d’Avila e Bolama, 6200 Covilhã (Portugal); Physics Group, Qazvin Branch, Islamic Azad University, Qazvin (Iran, Islamic Republic of); Ziaie, A.H., E-mail: ah_ziaie@sbu.ac.ir [Department of Physics, Shahid Beheshti University, G. C., Evin, 19839 Tehran (Iran, Islamic Republic of); Department of Physics, Shahid Bahonar University, PO Box 76175, Kerman (Iran, Islamic Republic of); Jalalzadeh, S., E-mail: shahram.jalalzadeh@unila.edu.br [Federal University of Latin-American Integration, Technological Park of Itaipu PO box 2123, Foz do Iguaçu-PR, 85867-670 (Brazil); Moniz, P.V., E-mail: pmoniz@ubi.pt [Departamento de Física, Universidade da Beira Interior, Rua Marquês d’Avila e Bolama, 6200 Covilhã (Portugal); Centro de Matemática e Aplicações (CMA - UBI), Universidade da Beira Interior, Rua Marquês d’Avila e Bolama, 6200 Covilhã (Portugal)

    2016-12-15

    We study the collapse process of a homogeneous perfect fluid (in FLRW background) with a barotropic equation of state in Brans–Dicke (BD) theory in the presence of phase space deformation effects. Such a deformation is introduced as a particular type of non-commutativity between phase space coordinates. For the commutative case, it has been shown in the literature (Scheel, 1995), that the dust collapse in BD theory leads to the formation of a spacetime singularity which is covered by an event horizon. In comparison to general relativity (GR), the authors concluded that the final state of black holes in BD theory is identical to the GR case but differs from GR during the dynamical evolution of the collapse process. However, the presence of non-commutative effects influences the dynamics of the collapse scenario and consequently a non-singular evolution is developed in the sense that a bounce emerges at a minimum radius, after which an expanding phase begins. Such a behavior is observed for positive values of the BD coupling parameter. For large positive values of the BD coupling parameter, when non-commutative effects are present, the dynamics of collapse process differs from the GR case. Finally, we show that for negative values of the BD coupling parameter, the singularity is replaced by an oscillatory bounce occurring at a finite time, with the frequency of oscillation and amplitude being damped at late times.

  9. Non-singular Brans–Dicke collapse in deformed phase space

    International Nuclear Information System (INIS)

    Rasouli, S.M.M.; Ziaie, A.H.; Jalalzadeh, S.; Moniz, P.V.

    2016-01-01

    We study the collapse process of a homogeneous perfect fluid (in FLRW background) with a barotropic equation of state in Brans–Dicke (BD) theory in the presence of phase space deformation effects. Such a deformation is introduced as a particular type of non-commutativity between phase space coordinates. For the commutative case, it has been shown in the literature (Scheel, 1995), that the dust collapse in BD theory leads to the formation of a spacetime singularity which is covered by an event horizon. In comparison to general relativity (GR), the authors concluded that the final state of black holes in BD theory is identical to the GR case but differs from GR during the dynamical evolution of the collapse process. However, the presence of non-commutative effects influences the dynamics of the collapse scenario and consequently a non-singular evolution is developed in the sense that a bounce emerges at a minimum radius, after which an expanding phase begins. Such a behavior is observed for positive values of the BD coupling parameter. For large positive values of the BD coupling parameter, when non-commutative effects are present, the dynamics of collapse process differs from the GR case. Finally, we show that for negative values of the BD coupling parameter, the singularity is replaced by an oscillatory bounce occurring at a finite time, with the frequency of oscillation and amplitude being damped at late times.

  10. Effect of accretion on primordial black holes in Brans-Dicke theory

    International Nuclear Information System (INIS)

    Nayak, B.; Singh, L. P.; Majumdar, A. S.

    2009-01-01

    We consider the effect of accretion of radiation in the early Universe on primordial black holes in Brans-Dicke theory. The rate of growth of a primordial black hole due to accretion of radiation in Brans-Dicke theory is considerably smaller than the rate of growth of the cosmological horizon, thus making available sufficient radiation density for the black hole to accrete causally. We show that accretion of radiation by Brans-Dicke black holes overrides the effect of Hawking evaporation during the radiation dominated era. The subsequent evaporation of the black holes in later eras is further modified due to the variable gravitational 'constant', and they could survive up to longer times compared to the case of standard cosmology. We estimate the impact of accretion on modification of the constraint on their initial mass fraction obtained from the γ-ray background limit from presently evaporating primordial black holes.

  11. Holographic dark energy in Brans-Dicke cosmology with chameleon scalar field

    International Nuclear Information System (INIS)

    Setare, M.R.; Jamil, Mubasher

    2010-01-01

    We study a cosmological implication of holographic dark energy in the Brans-Dicke gravity. We employ the holographic model of dark energy to obtain the equation of state for the holographic energy density in non-flat (closed) universe enclosed by the event horizon measured from the sphere of horizon named L. Our analysis shows that one can obtain the phantom crossing scenario if the model parameter α (of order unity) is tuned accordingly. Moreover, this behavior is achieved by treating the Brans-Dicke scalar field as a Chameleon scalar field and taking a non-minimal coupling of the scalar field with matter. Hence one can generate phantom-like equation of state from a holographic dark energy model in non-flat universe in the Brans-Dicke cosmology framework.

  12. Holographic dark energy in Brans-Dicke cosmology with chameleon scalar field

    Energy Technology Data Exchange (ETDEWEB)

    Setare, M.R., E-mail: rezakord@ipm.i [Department of Science of Bijar, University of Kurdistan, Bijar (Iran, Islamic Republic of); Jamil, Mubasher, E-mail: mjamil@camp.edu.p [Center for Advanced Mathematics and Physics, National University of Sciences and Technology, Rawalpindi 46000 (Pakistan)

    2010-06-07

    We study a cosmological implication of holographic dark energy in the Brans-Dicke gravity. We employ the holographic model of dark energy to obtain the equation of state for the holographic energy density in non-flat (closed) universe enclosed by the event horizon measured from the sphere of horizon named L. Our analysis shows that one can obtain the phantom crossing scenario if the model parameter {alpha} (of order unity) is tuned accordingly. Moreover, this behavior is achieved by treating the Brans-Dicke scalar field as a Chameleon scalar field and taking a non-minimal coupling of the scalar field with matter. Hence one can generate phantom-like equation of state from a holographic dark energy model in non-flat universe in the Brans-Dicke cosmology framework.

  13. Dicke superradiance as nondestructive probe for the state of atoms in optical lattices

    Science.gov (United States)

    ten Brinke, Nicolai; Schützhold, Ralf

    2016-04-01

    We present a proposal for a probing scheme utilizing Dicke superradiance to obtain information about ultracold atoms in optical lattices. A probe photon is absorbed collectively by an ensemble of lattice atoms generating a Dicke state. The lattice dynamics (e.g., tunneling) affects the coherence properties of that Dicke state and thus alters the superradiant emission characteristics - which in turn provides insight into the lattice (dynamics). Comparing the Bose-Hubbard and the Fermi-Hubbard model, we find similar superradiance in the strongly interacting Mott insulator regime, but crucial differences in the weakly interacting (superfluid or metallic) phase. Furthermore, we study the possibility to detect whether a quantum phase transition between the two regimes can be considered adiabatic or a quantum quench.

  14. γ parameter and Solar System constraint in chameleon-Brans-Dicke theory

    International Nuclear Information System (INIS)

    Saaidi, Kh.; Mohammadi, A.; Sheikhahmadi, H.

    2011-01-01

    The post Newtonian parameter is considered in the chameleon-Brans-Dicke model. In the first step, the general form of this parameter and also effective gravitational constant is obtained. An arbitrary function for f(Φ), which indicates the coupling between matter and scalar field, is introduced to investigate validity of solar system constraint. It is shown that the chameleon-Brans-Dicke model can satisfy the solar system constraint and gives us an ω parameter of order 10 4 , which is in comparable to the constraint which has been indicated in [19].

  15. Dicke coherent narrowing in two-photon and Raman spectroscopy of thin vapor cells

    International Nuclear Information System (INIS)

    Dutier, Gabriel; Todorov, Petko; Hamdi, Ismahene; Maurin, Isabelle; Saltiel, Solomon; Bloch, Daniel; Ducloy, Martial

    2005-01-01

    The principle of coherent Dicke narrowing in a thin vapor cell, in which sub-Doppler spectral line shapes are observed under a normal irradiation for a λ/2 thickness, is generalized to two-photon spectroscopy. Only the sum of the two wave vectors must be normal to the cell, making the two-photon scheme highly versatile. A comparison is provided between the Dicke narrowing with copropagating fields, and the residual Doppler broadening occurring with counterpropagating geometries. The experimental feasibility is discussed on the basis of a first observation of a two-photon resonance in a 300-nm-thick Cs cell. Extension to the Raman situation is finally considered

  16. Possible observational manifestations of wormholes in the Brans-Dicke theory

    Energy Technology Data Exchange (ETDEWEB)

    Alexeyev, S. O., E-mail: alexeyev@sai.msu.ru; Rannu, K. A., E-mail: rannu@xray.sai.msu.ru [Sternberg Astronomical Institute (Russian Federation); Gareeva, D. V., E-mail: 4elesta@mail.ru [Moscow State University (Russian Federation)

    2011-10-15

    The energy flux emitted during the accretion of matter onto a wormhole in the Brans-Dicke theory has been calculated. This characteristic is compared with its values calculated previously for wormholes in general relativity and for a Schwarzschild black hole.

  17. Brans-Dicke theory in general space-time with torsion

    International Nuclear Information System (INIS)

    Kim, S.

    1986-01-01

    The Brans-Dicke theory in the general space-time endowed with torsion is investigated. Since the gradient of the scalar field as well as the intrinsic spin generate the torsion field, the interaction term of the spin-scalar field appears in the wave equation. The equations of motion are satisfied with the conservation laws

  18. A Quintessence Problem in Self-interacting Brans-Dicke Theory

    OpenAIRE

    Chakraborty, Subenoy; Chakraborty, N. C.; Debnath, Ujjal

    2003-01-01

    A quintessence scalar field in self-interacting Brans-Dicke theory is shown to give rise to a non-decelerated expansion of the present universe for open, flat and closed models. Along with providing a non-decelerating solution, it can potentially solve the flatness problem too.

  19. Launch Window Trade Analysis for the James Webb Space Telescope

    Science.gov (United States)

    Yu, Wayne H.; Richon, Karen

    2014-01-01

    The James Webb Space Telescope (JWST) is a large-scale space telescope mission designed to study fundamental astrophysical questions ranging from the formation of the universe to the origin of planetary systems and the origins of life. JWSTs orbit design is a Libration Point Orbit (LPO) around the Sun-Earth/Moon (SEM) L2 point for a planned mission lifetime of 10.5 years. The launch readiness period for JWST is from Oct 1st, 2018 November 30th, 2018. This paper presents the first launch window analysis for the JWST observatory using finite-burn modeling; previous analysis assumed a single impulsive midcourse correction to achieve the mission orbit. The physical limitations of the JWST hardware stemming primarily from propulsion, communication and thermal requirements alongside updated mission design requirements result in significant launch window within the launch readiness period. Future plans are also discussed.

  20. Solar System Observations with the James Webb Space Telescope

    Science.gov (United States)

    Norwood, James; Hammel, Heidi; Milam, Stefanie; Stansberry, John; Lunine, Jonathan; Chanover, Nancy; Hines, Dean; Sonneborn, George; Tiscareno, Matthew; Brown, Michael; hide

    2016-01-01

    The James Webb Space Telescope (JWST) will enable a wealth of new scientific investigations in the near- and mid-infrared, with sensitivity and spatial/spectral resolution greatly surpassing its predecessors. In this paper, we focus upon Solar System science facilitated by JWST, discussing the most current information available concerning JWST instrument properties and observing techniques relevant to planetary science. We also present numerous example observing scenarios for a wide variety of Solar System targets to illustrate the potential of JWST science to the Solar System community. This paper updates and supersedes the Solar System white paper published by the JWST Project in 2010. It is based both on that paper and on a workshop held at the annual meeting of the Division for Planetary Sciences in Reno, NV, in 2012.

  1. Integrated Modeling for the James Webb Space Telescope (JWST) Project: Structural Analysis Activities

    Science.gov (United States)

    Johnston, John; Mosier, Mark; Howard, Joe; Hyde, Tupper; Parrish, Keith; Ha, Kong; Liu, Frank; McGinnis, Mark

    2004-01-01

    This paper presents viewgraphs about structural analysis activities and integrated modeling for the James Webb Space Telescope (JWST). The topics include: 1) JWST Overview; 2) Observatory Structural Models; 3) Integrated Performance Analysis; and 4) Future Work and Challenges.

  2. The Value of Long-Term Research at the Five USGS WEBB Catchments

    Science.gov (United States)

    Shanley, J. B.; Murphy, S. F.; Scholl, M. A.; Wickland, K.; Aulenbach, B. T.; Hunt, R.; Clow, D. W.

    2017-12-01

    Long-term catchment studies are sentinel sites for detecting, documenting, and understanding ecosystem processes and environmental change. The small catchment approach fosters in-depth site-based hydrological, biogeochemical, and ecological process understanding, while a collective network of catchment observatories offers a broader context to synthesize understanding across a range of climates and geologies. The USGS Water, Energy, and Biogeochemical Budgets (WEBB) program is a network of five sites established in 1991 to assess the impact of climate and environmental change on hydrology and biogeochemistry. Like other networks, such as the USDA - Forest Service Experimental Forests and the Czech Geomon network, WEBB exploits gradients of climate, geology, and topography to understand controls on biogeochemical processes. We present examples from each site and some cross-site syntheses to demonstrate how WEBB has advanced catchment science and informed resource management and policy. WEBB has relied on strong academic partnerships, providing long-term continuity for shorter-term academic grants, which have offered rich graduate educational opportunities. Like other sites and networks, the long-term datasets and process understanding of WEBB provide context to detect and interpret change. Without this backdrop, we have no baseline to quantify effects of droughts, floods, and extreme events, and no test sites to validate process-based models. In an era of lean budgets for science funding, the long-term continuity of WEBB and other catchment networks is in jeopardy, as is the critical scientific value and societal benefits they embody.

  3. Using New Media to Spread the Word About the James Webb Space Telescope

    Science.gov (United States)

    Masetti, Maggie; Krishnamurthi, A.

    2008-05-01

    The James Webb Space Telescope is a 6.5 m infrared telescope that will be launched in 2013. This modern telescope will look very different from the simple telescope Galileo used to look up at the skies 400 years ago. Modern technology, coupled with scientific curiosity, is enabling science to help us understand a Universe Galileo had not dreamed of in his time. The International Year of Astronomy presents an excellent opportunity to take the public along on the journey of the development of the Webb Telescope and its technological innovations. In keeping with the cutting-edge nature of the Webb, its education and public outreach (EPO) team is using a variety of new media to engage the public. We will discuss several of our EPO projects including our website, exhibits and displays in Second Life (an internet-based virtual world), and involvement in podcasts. Webb's EPO team is looking to expand past a passive web presence to engage the new and growing internet-savvy audiences. We are making our website more interactive through a variety of means, including a Flash game that allows the user to compare the Webb to a common reflecting telescope. This will enable the user to learn about the changes in telescopes that have come about since Galileo's time. We are also taking advantage of other new media opportunities as they present themselves - we participate in podcasts and have an engaging presence for the Webb Telescope on NASA's "islands” in Second Life.

  4. Negotiating Transcendentalism, Escaping « Paradise » : Herman Melville’s Moby-Dick.

    Directory of Open Access Journals (Sweden)

    Ramón Espejo Romero

    2010-06-01

    Full Text Available By reviewing the critical literature on Melville and Transcendentalism and then undertaking a close reading of Moby-Dick (1851, this paper argues that the novel reflects, among other things, an ongoing debate between the novelist and Transcendentalist philosophy. While in later works, Melville seems to express a more robust condemnation of the Concord movement and its dangerous idealism, Moby-Dick occupies less firmly-defined territory. The Transcendentalist urge of an Ahab to be himself is a counterpoint to Ishmael’s more idiosyncratic deployment of self-reliance, communion with the oversoul, and various other concepts easy to trace back to Emerson or Thoreau. The conclusion seems to be that a negotiation is necessary if Transcendentalism is to be heeded at all, precisely the kind of negotiation Ishmael undertakes throughout the novel, one which spares him from the maelstrom created by a more radical approach to self-acceptance and self-fashioning.

  5. Parameterized post-Newtonian coefficients for Brans-Dicke gravity with d + 1 dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Klimek, Matthew D, E-mail: klimek@physics.rutgers.ed [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States)

    2009-03-21

    We present calculations of post-Newtonian parameters for Brans-Dicke tensor-scalar gravity in an arbitrary number of compact extra dimensions in both the Jordan and Einstein conformal frames. We find that the parameter gamma, which measures the amount of spacetime curvature per unit mass, becomes a function of omega, the coefficient of the scalar kinetic term in the Brans-Dicke Lagrangian. Experiment has placed strong constraints on gamma which require that omega becomes negative in the Jordan frame for any number of extra dimensions, highlighting that this formulation is not physical. We also confirm the well-known result that a compact extra dimension can be equivalently viewed as a massless scalar 'dilaton.' In the Einstein frame, we find that the behavior of gamma as constrained by experiment replicates that which is predicted by string theory.

  6. First-Order Quantum Phase Transition for Dicke Model Induced by Atom-Atom Interaction

    International Nuclear Information System (INIS)

    Zhao Xiu-Qin; Liu Ni; Liang Jiu-Qing

    2017-01-01

    In this article, we use the spin coherent state transformation and the ground state variational method to theoretically calculate the ground function. In order to consider the influence of the atom-atom interaction on the extended Dicke model’s ground state properties, the mean photon number, the scaled atomic population and the average ground energy are displayed. Using the self-consistent field theory to solve the atom-atom interaction, we discover the system undergoes a first-order quantum phase transition from the normal phase to the superradiant phase, but a famous Dicke-type second-order quantum phase transition without the atom-atom interaction. Meanwhile, the atom-atom interaction makes the phase transition point shift to the lower atom-photon collective coupling strength. (paper)

  7. Effect of a Brans--Dicke cosmology upon stellar evolution and the evolution of galaxies

    International Nuclear Information System (INIS)

    Prather, M.J.

    1976-01-01

    The effect which a variable G cosmology, such as Brans-Dicke, will have on the evolution of individual stars and of galaxies composed of these stars is examined in the hope that present day observation of globular clusters or giant elliptical galaxies will provide a test for the Brans--Dicke theory. The higher value of the gravitational coupling coefficient G in the past history of various Brans--Dicke universes is studied in detail. A low density, open universe is selected for study: fractional closure density = 0.2, present Hubble constant = km/s/Mpc, stellar formation at a red-shift of 5, and the Brans--Dicke parameter omega = 6. In this universe a set of stellar evolutionary tracks is computed from the Zero-Age Main Sequence through the Giant Branch to the Horizontal Branch for approximately solar composition, (Y,Z) = (0.25, 0.02). When compared at equivalent evolutionary phases, the luminosity of individual stars is found to increase greatly with G from the ZAMS to the HB. The higher G greatly speeds up the evolutionary time scale for the main sequence, and it decreases the core mass at the helium flash, leaving the luminosity of the tip of the GB and the HB unchanged. The net effect of a higher G on a cluster of stars is to increase the apparent mass at the turn-off and to reduce the lifetimes of all the evolutionary phases from the ZAMS to the HB by the same factor. Thus, the relative number density of stars in the major phases of stellar evolution is unchanged

  8. Stability analysis and observational measurement in chameleonic generalised Brans-Dicke cosmology

    International Nuclear Information System (INIS)

    Farajollahi, Hossein; Salehi, Amin

    2011-01-01

    We investigate the dynamics of the chameleonic Generalised Brans-Dicke model in flat FRW cosmology. In a new approach, a framework to study stability and attractor solutions in the phase space for the model is developed by simultaneously best fitting the stability and model parameters with the observational data. The results show that for an accelerating universe the phantom crossing does not occur in the past and near future

  9. Generation of Symmetric Dicke States of Remote Qubits with Linear Optics

    International Nuclear Information System (INIS)

    Thiel, C.; Zanthier, J. von; Bastin, T.; Solano, E.; Agarwal, G. S.

    2007-01-01

    We propose a method for generating all symmetric Dicke states, either in the long-lived internal levels of N massive particles or in the polarization degrees of freedom of photonic qubits, using linear optical tools only. By means of a suitable multiphoton detection technique, erasing Welcher-Weg information, our proposed scheme allows the generation and measurement of an important class of entangled multiqubit states

  10. Gödel and Gödel-type universes in Brans–Dicke theory

    Energy Technology Data Exchange (ETDEWEB)

    Agudelo, J.A., E-mail: jaar@fisica.ufmt.br [Instituto de Física, Universidade Federal de Mato Grosso, 78060-900, Cuiabá, Mato Grosso (Brazil); Nascimento, J.R., E-mail: jroberto@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-970, João Pessoa, Paraíba (Brazil); Petrov, A.Yu., E-mail: petrov@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-970, João Pessoa, Paraíba (Brazil); Porfírio, P.J., E-mail: pporfirio@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-970, João Pessoa, Paraíba (Brazil); Santos, A.F., E-mail: alesandroferreira@fisica.ufmt.br [Instituto de Física, Universidade Federal de Mato Grosso, 78060-900, Cuiabá, Mato Grosso (Brazil); Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road Victoria, BC (Canada)

    2016-11-10

    In this paper, conditions for existence of Gödel and Gödel-type solutions in Brans–Dicke (BD) scalar–tensor theory and their main features are studied. The consistency of equations of motion, causality violation and existence of CTCs (closed time-like curves) are investigated. The role which cosmological constant and Mach principle play to achieve the consistency of this model is studied.

  11. Cylindrically symmetric, static strings with a cosmological constant in Brans-Dicke theory

    International Nuclear Information System (INIS)

    Delice, Oezguer

    2006-01-01

    The static cylindrically symmetric vacuum solutions with a cosmological constant in the framework of the Brans-Dicke theory are investigated. Some of these solutions admitting Lorentz boost invariance along the symmetry axis correspond to local, straight cosmic strings with a cosmological constant. Some physical properties of such solutions are studied. These strings apply attractive or repulsive forces on the test particles. A smooth matching is also performed with a recently introduced interior thick string solution with a cosmological constant

  12. Brans-Dicke Theory with Λ>0: Black Holes and Large Scale Structures.

    Science.gov (United States)

    Bhattacharya, Sourav; Dialektopoulos, Konstantinos F; Romano, Antonio Enea; Tomaras, Theodore N

    2015-10-30

    A step-by-step approach is followed to study cosmic structures in the context of Brans-Dicke theory with positive cosmological constant Λ and parameter ω. First, it is shown that regular stationary black-hole solutions not only have constant Brans-Dicke field ϕ, but can exist only for ω=∞, which forces the theory to coincide with the general relativity. Generalizations of the theory in order to evade this black-hole no-hair theorem are presented. It is also shown that in the absence of a stationary cosmological event horizon in the asymptotic region, a stationary black-hole horizon can support a nontrivial Brans-Dicke hair. Even more importantly, it is shown next that the presence of a stationary cosmological event horizon rules out any regular stationary solution, appropriate for the description of a star. Thus, to describe a star one has to assume that there is no such stationary horizon in the faraway asymptotic region. Under this implicit assumption generic spherical cosmic structures are studied perturbatively and it is shown that only for ω>0 or ω≲-5 their predicted maximum sizes are consistent with observations. We also point out how, many of the conclusions of this work differ qualitatively from the Λ=0 spacetimes.

  13. Optical transmission for the James Webb Space Telescope

    Science.gov (United States)

    Lightsey, Paul A.; Gallagher, Benjamin B.; Nickles, Neal; Copp, Tracy

    2012-09-01

    The fabrication and coating of the mirrors for the James Webb Space Telescope has been completed. The spectral reflectivity of the protected gold coated beryllium mirrors has been measured. The predicted end-of-life transmission through the telescope builds from these values. The additional phenomena that have been analyzed are contamination effects and effects of the environment for the JWST operation about the Earth-Sun L2 Lagrange libration point. The L2 environment analysis has been based on radiation testing of mirror samples and hypervelocity testing to assess the micrometeoroid impact effects. The mirror showed no change in reflectance over the VIS-SWIR wavelengths after exposure to 6-9 Grad (Si) that simulated 6 years orbiting the L2 Lagrange point. The effects of hypervelocity particle impacts on the mirrors from test data has been extrapolated to the to the anticipated flux characteristics for micrometeoroids at the L2 environment. The results show that the micrometeoroid effects are orders of magnitude below the particulate contamination effects. The final end-of-life transmission for the mirrors including all of these phenomena will meet the performance requirements for JWST.

  14. Combining Social Media with Innovative Ways of Communicating about the James Webb Space Telescope

    Science.gov (United States)

    Masetti, Margaret

    2012-01-01

    In keeping with the cutting-edge nature of the James Webb Space Telescope, NASA is using a variety of social and interactive media to engage the public. While we do have a regularly updated static website, we are now also using various interactives (like Flash games and a 3D Tour of the spacecraft) to better explain what the Webb telescope is and how it works. To encourage future generations, we are a partner in an educational engineering design challenge which makes use of a virtual Second Life-like world. Additionally, the public can now watch Webb come together before their eyes by accessing our live webcam, which shows telescope hardware being built in our cleanroom. We are working to make Webb as much of a part of pop culture as the Hubble Space Telescope is. We facilitated the filming of a "Late Night with Jimmy Fallon” segment (called "Hubble Gotchu") featuring Webb and Webb scientists at NASA's Goddard Space Flight Center. A visit to the highly rated sitcom "The Big Bang Theory” resulted in Webb lithos, magnets, posters, a scale model, and more being regularly featured on the set of the show. The most important aspect to creating interesting ways to engage the public is having the ability to communicate and form relationships with as many people as possible. To that end, we are using tools like blogs (e.g., NASA Blueshift) and popular social media (Facebook, Twitter, YouTube, and Flickr) to reach out to as many people as we can and to enable them to share and spread the content we provide.

  15. James Webb Telescope's Near Infrared Camera: Making Models, Building Understanding

    Science.gov (United States)

    Lebofsky, Larry A.; McCarthy, D. W.; Higgins, M. L.; Lebofsky, N. R.

    2010-10-01

    The Astronomy Camp for Girl Scout Leaders is a science education program sponsored by NASA's next large space telescope: The James Webb Space Telescope (JWST). The E/PO team for JWST's Near Infrared Camera (NIRCam), in collaboration with the Sahuaro Girl Scout Council, has developed a long-term relationship with adult leaders from all GSUSA Councils that directly benefits troops of all ages, not only in general science education but also specifically in the astronomical and technology concepts relating to JWST. We have been training and equipping these leaders so they can in turn teach young women essential concepts in astronomy, i.e., the night sky environment. We model what astronomers do by engaging trainers in the process of scientific inquiry, and we equip them to host troop-level astronomy-related activities. It is GSUSA's goal to foster girls’ interest and creativity in Science, Technology, Engineering, and Math, creating an environment that encourages their interests early in their lives while creating a safe place for girls to try and fail, and then try again and succeed. To date, we have trained over 158 leaders in 13 camps. These leaders have come from 24 states, DC, Guam, and Japan. While many of the camp activities are related to the "First Light” theme, many of the background activities relate to two of the other JWST and NIRCam themes: "Birth of Stars and Protoplanetary Systems” and "Planetary Systems and the Origin of Life.” The latter includes our own Solar System. Our poster will highlight the Planetary Systems theme: 1. Earth and Moon: Day and Night; Rotation and Revolution. 2. Earth/Moon Comparisons. 3. Size Model: The Diameters of the Planets. 4. Macramé Planetary (Solar) Distance Model. 5.What is a Planet? 6. Planet Sorting Cards. 7. Human Orrery 8. Lookback Time in Our Daily Lives NIRCam E/PO website: http://zeus.as.arizona.edu/ dmccarthy/GSUSA

  16. Dynamics of the Dicke model and superradiant state

    International Nuclear Information System (INIS)

    Bogolubov, N.N. Jr.; Kurbatov, A.M.; Kazaryan, A.R.; Neskoromnyi, V.N.

    1983-12-01

    A system of two-level atoms interacting with a photon field in the ''rotating wave'' approximation is investigated. For the Green's function of such a system an exact equation in which the variables of the photon field are eliminated is obtained. The self-consistent field approximation and the small value of the coupling constant are used to obtain a closed system of equations. The non-equilibrium superradiant conditions are derived. The influence of the initial conditions on the system's dynamics is studied. It is shown that if the temperature of photon heat bath is not equal to zero, the only way to superradiance is spatially inhomogeneous initial conditions. (author)

  17. Finding our Origins with the Hubble and James Webb Space Telescopes

    Science.gov (United States)

    Gardner, Jonathan P.

    2009-01-01

    NASA is planning a successor to the Hubble Space Telescope designed to study the origins of galaxies, stars, planets and life in the universe. In this talk, Dr. Gardner will discuss the origin and evolution of galaxies, beginning with the Big Bang and tracing what we have learned with Hubble through to the present day. He will show that results from studies with Hubble have led to plans for its successor, the James Webb Space Telescope. Webb is scheduled to launch in 2014, and is designed to find the first galaxies that formed in the distant past and to penetrate the dusty clouds of gas where stars are still forming today. He will compare Webb to Hubble, and discuss recent progress in the construction of the observatory.

  18. Selected achievements, science directions, and new opportunities for the WEBB small watershed research program

    Science.gov (United States)

    Glynn, Pierre D.; Larsen, Matthew C.; Greene, Earl A.; Buss, Heather L.; Clow, David W.; Hunt, Randall J.; Mast, M. Alisa; Murphy, Sheila F.; Peters, Norman E.; Sebestyen, Stephen D.; Shanley, James B.; Walker, John F.

    2009-01-01

    Over nearly two decades, the Water, Energy, and Biogeochemical Budgets (WEBB) small watershed research program of the U.S. Geological Survey (USGS) has documented how water and solute fluxes, nutrient, carbon, and mercury dynamics, and weathering and sediment transport respond to natural and humancaused drivers, including climate, climate change, and atmospheric deposition. Together with a continued and increasing focus on the effects of climate change, more investigations are needed that examine ecological effects (e.g., evapotranspiration, nutrient uptake) and responses (e.g., species abundances, biodiversity) that are coupled with the physical and chemical processes historically observed in the WEBB program. Greater use of remote sensing, geographic modeling, and habitat/watershed modeling tools is needed, as is closer integration with the USGS-led National Phenology Network. Better understanding of process and system response times is needed. The analysis and observation of land-use and climate change effects over time should be improved by pooling data obtained by the WEBB program during the last two decades with data obtained earlier and (or) concurrently from other research and monitoring studies conducted at or near the five WEBB watershed sites. These data can be supplemented with historical and paleo-environmental information, such as could be obtained from tree rings and lake cores. Because of the relatively pristine nature and small size of its watersheds, the WEBB program could provide process understanding and basic data to better characterize and quantify ecosystem services and to develop and apply indicators of ecosystem health. In collaboration with other Federal and State watershed research programs, the WEBB program has an opportunity to contribute to tracking the short-term dynamics and long-term evolution of ecosystem services and health indicators at a multiplicity of scales across the landscape. 

  19. Evolution of Bianchi I magnetized cosmic strings in Brans–Dicke gravity

    International Nuclear Information System (INIS)

    Sharif, M; Waheed, Saira

    2013-01-01

    In this paper, we consider a locally rotationally symmetric Bianchi I universe filled with magnetized viscous string fluid in Brans–Dicke gravity. For the exact solutions, we use the law of variation of the Hubble parameter that leads to volumetric expansion laws and assume power law ansatz for the scalar field. We discuss the nature of the resulting models through different parameters and their graphs. It is concluded that the constructed universe models yield an accelerated expanding behavior with an isotropic nature for the final stages of the universe evolution, which is consistent with recent observations. (paper)

  20. Attractors, statefinders and observational measurement for chameleonic Brans-Dicke cosmology

    International Nuclear Information System (INIS)

    Farajollahi, Hossein; Salehi, Amin

    2010-01-01

    We investigate chameleonic Brans-Dicke model applied to the FRW universes. A framework to study stability and attractor solutions in the phase space is developed for the model. We show that depending on the matter field and stability conditions, it is possible to realize phantom-like behavior without introducing phantom filed in the model while the stability is fulfilled and phantom crossing occurs. The statefinder parameters to the model for different kinds of matter interacting with the chameleon scalar field are studied. We also compare our model with present day observations

  1. Attractors, statefinders and observational measurement for chameleonic Brans-Dicke cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Farajollahi, Hossein; Salehi, Amin, E-mail: hosseinf@guilan.ac.ir, E-mail: a.salehi@guilan.ac.ir [Department of Physics, University of Guilan, Rasht (Iran, Islamic Republic of)

    2010-11-01

    We investigate chameleonic Brans-Dicke model applied to the FRW universes. A framework to study stability and attractor solutions in the phase space is developed for the model. We show that depending on the matter field and stability conditions, it is possible to realize phantom-like behavior without introducing phantom filed in the model while the stability is fulfilled and phantom crossing occurs. The statefinder parameters to the model for different kinds of matter interacting with the chameleon scalar field are studied. We also compare our model with present day observations.

  2. Lacan leitor de Melanie Klein: O caso Dick em questão

    OpenAIRE

    Lucero, Ariana; Vorcaro, Angela Maria Resende

    2017-01-01

    RESUMO - O artigo apresenta a leitura que Jacques Lacan faz do caso Dick, de Melanie Klein. Para tanto, a discussão com o flósofo Jean Hyppolite é retomada com o objetivo de explicitarmos como os mecanismos de Ausstossung [expulsão], Verneinung [negação] e Bejahung [afrmação], descritos por Freud em 1925, podem contribuir para a compreensão da constituição psíquicasob uma perspectiva lacaniana. Em seguida, expomos o caso, tanto para apreendermos clinicamente o que foi exposto na teoria, quant...

  3. Elliptic solutions of generalized Brans-Dicke gravity with a non-universal coupling

    Energy Technology Data Exchange (ETDEWEB)

    Alimi, J.M.; Reverdy, V. [Observatoire de Paris, Laboratoire Univers et Theories (LUTh), Meudon (France); Golubtsova, A.A. [Observatoire de Paris, Laboratoire Univers et Theories (LUTh), Meudon (France); Peoples' Friendship University of Russia, Institute of Gravitation and Cosmology, Moscow (Russian Federation)

    2014-10-15

    We study a model of the generalized Brans-Dicke gravity presented in both the Jordan and in the Einstein frames, which are conformally related. We show that the scalar field equations in the Einstein frame are reduced to the geodesics equations on the target space of the nonlinear sigma model. The analytical solutions in elliptical functions are obtained when the conformal couplings are given by reciprocal exponential functions. The behavior of the scale factor in the Jordan frame is studied using numerical computations. For certain parameters the solutions can describe an accelerated expansion. We also derive an analytical approximation in exponential functions. (orig.)

  4. Time variation of the cosmological redshift in Dicke-Brans-Jordan cosmologies

    International Nuclear Information System (INIS)

    Ruediger, R.

    1982-01-01

    In this paper the time variation z of the cosmological redshift z is discussed for Dicke-Brans-Jordan (DBJ) cosmologies. We determine the general z-z relation in the functional form zH -1 0 = F(z; q 0 , sigma 0 ,xi 0 , ω) for small values of z, where all the symbols have their conventional meanings. For certain combinations of cosmological parameters, which are within the present observational limitations, the DBJ terms in the function F can dominate the general relativistic terms. Furthermore, zH -1 0 can be positive in DBJ cosmologies in contrast to general relativistic cosmologies with q 0 >0

  5. Application of the functional integration method to the Dicke-type models

    International Nuclear Information System (INIS)

    Popov, V.N.; Fedotov, S.A.

    1981-01-01

    The asymptotics of the statistical model sum of the Dicke-type (Z/Z 6 ) is obtained and strictly proved at large N (N is an atomic number; Z is a statistical model sum; Z 0 is a statistical free system sum) using the functional integration method. The model with one bose-field mode is considered. A detailed proof is carried out at T > Tsub(c). An idea of the proof is planned and asymptotic formulae are presented for T < Tsub(c) and in the vicinity of Tsub(c)

  6. Inflationary phase in Brans-Dicke cosmology with a cosmological constant

    Science.gov (United States)

    Berman, Marcelo Samuel

    1989-12-01

    It has been shown earlier that, for a perfect fluid, a perfect gas law of state, and the Robertson-Walker metric, an exponential phase in Brans-Dicke cosmology is possible, with both positive pressure and density, but not with the violated energy condition p = -ρ. We demonstrate in this paper that the inclusion of a cosmological constant into the theory does not change that picture. Permanent address: Departamento de Ciencias Exatas da Faculdade de Filosofia, Ceincias e Letras da FURJ, Joinville, SC 89200, Brazil.

  7. James Webb Space Telescope Optical Telescope Element Mirror Development History and Results

    Science.gov (United States)

    Feinber, Lee D.; Clampin, Mark; Keski-Kuha, Ritva; Atkinson, Charlie; Texter, Scott; Bergeland, Mark; Gallagher, Benjamin B.

    2012-01-01

    In a little under a decade, the James Webb Space Telescope (JWST) program has designed, manufactured, assembled and tested 21 flight beryllium mirrors for the James Webb Space Telescope Optical Telescope Element. This paper will summarize the mirror development history starting with the selection of beryllium as the mirror material and ending with the final test results. It will provide an overview of the technological roadmap and schedules and the key challenges that were overcome. It will also provide a summary or the key tests that were performed and the results of these tests.

  8. XML: James Webb Space Telescope Database Issues, Lessons, and Status

    Science.gov (United States)

    Detter, Ryan; Mooney, Michael; Fatig, Curtis

    2003-01-01

    This paper will present the current concept using extensible Markup Language (XML) as the underlying structure for the James Webb Space Telescope (JWST) database. The purpose of using XML is to provide a JWST database, independent of any portion of the ground system, yet still compatible with the various systems using a variety of different structures. The testing of the JWST Flight Software (FSW) started in 2002, yet the launch is scheduled for 2011 with a planned 5-year mission and a 5-year follow on option. The initial database and ground system elements, including the commands, telemetry, and ground system tools will be used for 19 years, plus post mission activities. During the Integration and Test (I&T) phases of the JWST development, 24 distinct laboratories, each geographically dispersed, will have local database tools with an XML database. Each of these laboratories database tools will be used for the exporting and importing of data both locally and to a central database system, inputting data to the database certification process, and providing various reports. A centralized certified database repository will be maintained by the Space Telescope Science Institute (STScI), in Baltimore, Maryland, USA. One of the challenges for the database is to be flexible enough to allow for the upgrade, addition or changing of individual items without effecting the entire ground system. Also, using XML should allow for the altering of the import and export formats needed by the various elements, tracking the verification/validation of each database item, allow many organizations to provide database inputs, and the merging of the many existing database processes into one central database structure throughout the JWST program. Many National Aeronautics and Space Administration (NASA) projects have attempted to take advantage of open source and commercial technology. Often this causes a greater reliance on the use of Commercial-Off-The-Shelf (COTS), which is often limiting

  9. Brans-Dicke inflation in light of the Planck 2015 data

    Energy Technology Data Exchange (ETDEWEB)

    Tahmasebzadeh, B. [Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), P.O. Box 45195-1159, Zanjan (Iran, Islamic Republic of); Rezazadeh, K.; Karami, K., E-mail: b.tahmasebzadeh@iasbs.ac.ir, E-mail: rezazadeh86@gmail.com, E-mail: kkarami@uok.ac.ir [Department of Physics, University of Kurdistan, Pasdaran St., P.O. Box 66177-15175, Sanandaj (Iran, Islamic Republic of)

    2016-07-01

    We study inflation in the Brans-Dicke gravity as a special model of the scalar-tensor gravity. We obtain the inflationary observables containing the scalar spectral index, the tensor-to-scalar ratio, the running of the scalar spectral index and the equilateral non-Gaussianity parameter in terms of the general form of the potential in the Jordan frame. Then, we compare the results for various inflationary potentials in light of the Planck 2015 data. Our study shows that in the Brans-Dicke gravity, the power-law, inverse power-law and exponential potentials are ruled out by the Planck 2015 data. But, the hilltop, Higgs, Coleman-Weinberg and natural potentials can be compatible with Planck 2015 TT,TE,EE+lowP data at 95% CL. Moreover, the D-brane, SB SUSY and displaced quadratic potentials can be in well agreement with the observational data since their results can lie inside the 68% CL region of Planck 2015 TT,TE,EE+lowP data.

  10. Notes on the post-Newtonian limit of the massive Brans-Dicke theory

    International Nuclear Information System (INIS)

    Roshan, Mahmood; Shojai, Fatimah

    2011-01-01

    We consider the post-Newtonian limit of the massive Brans-Dicke theory and make some notes about the post-Newtonian limit of the case ω = 0. This case is dynamically equivalent to the metric f(R) theory. It is known that this theory can be compatible with the solar system tests if the Chameleon mechanism occurs. Also, it is known that this mechanism is because of the nonlinearity in the field equations produced by the largeness of the local curvature relative to the background curvature. Thus, the linearization of the field equations breaks down. On the other hand, we know that the Chameleon mechanism exists when a coupling between the matter and the scalar field exists. In the Jordan frame of the Brans-Dicke theory, we have no such coupling. But in the Einstein frame, this theory behaves like a Chameleon scalar field. By confining ourselves to the case ω = 0, we show that 'Chameleon-like' behaviour can exist also in the Jordan frame, but it has an important difference compared with the Chameleon mechanism. Also we show that the conditions which lead to the existence of a 'Chameleon-like' mechanism are consistent with the conditions in the post-Newtonian limit which correspond to a heavy scalar field at the cosmological scale and a small effective cosmological constant. Thus, one can linearize field equations to the post-Newtonian order, and this linearization has no contradiction with the existence of 'Chameleon-like' behaviour.

  11. Holographic Dark Energy in Brans-Dicke Theory with Logarithmic Form of Scalar Field

    Science.gov (United States)

    Singh, C. P.; Kumar, Pankaj

    2017-10-01

    In this paper, an interacting holographic dark energy model with Hubble horizon as an infra-red cut-off is considered in the framework of Brans-Dicke theory. We assume the Brans-Dicke scalar field as a logarithmic form ϕ = ϕ 0 l n( α + β a), where a is the scale factor, α and β are arbitrary constants, to interpret the physical phenomena of the Universe. The equation of state parameter w h and deceleration parameter q are obtained to discuss the dynamics of the evolution of the Universe. We present a unified model of holographic dark energy which explains the early time acceleration (inflation), medieval time deceleration and late time acceleration. It is also observed that w h may cross the phantom divide line in the late time evolution. We also discuss the cosmic coincidence problem. We obtain a time-varying density ratio of holographic dark energy to dark matter which is a constant of order one (r˜ O(1)) during early and late time evolution, and may evolve sufficiently slow at present time. Thus, the model successfully resolves the cosmic coincidence problem.

  12. Brans-Dicke inflation in light of the Planck 2015 data

    International Nuclear Information System (INIS)

    Tahmasebzadeh, B.; Rezazadeh, K.; Karami, K.

    2016-01-01

    We study inflation in the Brans-Dicke gravity as a special model of the scalar-tensor gravity. We obtain the inflationary observables containing the scalar spectral index, the tensor-to-scalar ratio, the running of the scalar spectral index and the equilateral non-Gaussianity parameter in terms of the general form of the potential in the Jordan frame. Then, we compare the results for various inflationary potentials in light of the Planck 2015 data. Our study shows that in the Brans-Dicke gravity, the power-law, inverse power-law and exponential potentials are ruled out by the Planck 2015 data. But, the hilltop, Higgs, Coleman-Weinberg and natural potentials can be compatible with Planck 2015 TT,TE,EE+lowP data at 95% CL. Moreover, the D-brane, SB SUSY and displaced quadratic potentials can be in well agreement with the observational data since their results can lie inside the 68% CL region of Planck 2015 TT,TE,EE+lowP data.

  13. Stellar explosion in the weak field approximation of the Brans-Dicke theory

    International Nuclear Information System (INIS)

    Hamity, Victor H; Barraco, Daniel E

    2005-01-01

    We treat a very crude model of an exploding star, in the weak field approximation of the Brans-Dicke theory, in a scenario that resembles some characteristic data of a type Ia supernova. The most noticeable feature, in the electromagnetic component, is the relationship between the absolute magnitude at maximum brightness of the star and the decline rate in one magnitude from that maximum. This characteristic has become one of the most accurate methods to measure luminosity distances to objects at cosmological distances (Phillips M M 1993 Astrophys. J. 413 L105; see www.all-science-fair-projects.com/ science f air p rojects e ncyclopedia/Supernova, for a brief description of supernovae types). An interesting result is that the active mass associated with the scalar field is totally radiated to infinity, representing a mass loss in the ratio of the 'tensor' component to the scalar component of 1 to (2ω + 3) (ω is the Brans-Dicke parameter), in agreement with a general result of Hawking (1972 Commun. Math. Phys. 25 167). Then, this model shows explicitly, in a dynamical case, the mechanism of the radiation of a scalar field, which is necessary to understand the Hawking result

  14. Exact scaling solutions in normal and Brans-Dicke models of dark energy

    International Nuclear Information System (INIS)

    Arias, Olga; Gonzalez, Tame; Leyva, Yoelsy; Quiros, Israel

    2003-01-01

    A linear relationship between the Hubble expansion parameter and the time derivative of the scalar field is explored in order to derive exact cosmological, attractor-like solutions, both in Einstein's theory and in Brans-Dicke gravity with two fluids: a background fluid of ordinary matter and a self-interacting scalar-field fluid accounting for the dark energy in the universe. A priori assumptions about the functional form of the self-interaction potential or about the scale factor behaviour are not necessary. These are obtained as outputs of the assumed relationship between the Hubble parameter and the time derivative of the scalar field. A parametric class of scaling quintessence models given by a self-interaction potential of a peculiar form, a combination of exponentials with dependence on the barotropic index of the background fluid, arises. Both normal quintessence described by a self-interacting scalar field minimally coupled to gravity and Brans-Dicke quintessence given by a non-minimally coupled scalar field are then analysed and the relevance of these models for the description of the cosmic evolution is discussed in some detail. The stability of these solutions is also briefly commented on

  15. Spectroscopy of Atomic Vapors in Nanometer Cells: Dicke Narrowing and Beyond

    International Nuclear Information System (INIS)

    Vartanyan, T A; Khromov, V V

    2012-01-01

    Sub-Doppler spectroscopy of gaseous media confined in thin pillbox-shaped cells was pioneered by R.H. Dicke. In the past, this idea attracted much less attention compared to 'Dicke narrowing' in buffer gas where the atoms or molecules perform a diffusive motion instead of being bounced back and forth between the walls of the cell in a completely predetermined nature. The situation is going to be changed as atomic spectroscopy becoming an essential part of mobile devices for civil and military applications that require tiny spectroscopic cells. In the pillbox shaped cells, the role of the fast moving atoms is diminished, while the slowly moving atoms contribute most to the absorption as well as to the fluorescence. The role of the slowly moving atoms and their transient polarization in selective reflection spectroscopy was highlighted by J.L. Cojan. By merging these two approaches we have developed a theoretical description of optical reflection from and transmission through the narrow slice of atomic vapours.

  16. Robert Dicke and the naissance of experimental gravity physics, 1957-1967

    Science.gov (United States)

    Peebles, Phillip James Edwin

    2017-06-01

    The experimental study of gravity became much more active in the late 1950s, a change pronounced enough be termed the birth, or naissance, of experimental gravity physics. I present a review of developments in this subject since 1915, through the broad range of new approaches that commenced in the late 1950s, and up to the transition of experimental gravity physics to what might be termed a normal and accepted part of physical science in the late 1960s. This review shows the importance of advances in technology, here as in all branches of natural science. The role of contingency is illustrated by Robert Dicke's decision in the mid-1950s to change directions in mid-career, to lead a research group dedicated to the experimental study of gravity. The review also shows the power of nonempirical evidence. Some in the 1950s felt that general relativity theory is so logically sound as to be scarcely worth the testing. But Dicke and others argued that a poorly tested theory is only that, and that other nonempirical arguments, based on Mach's Principle and Dirac's Large Numbers hypothesis, suggested it would be worth looking for a better theory of gravity. I conclude by offering lessons from this history, some peculiar to the study of gravity physics during the naissance, some of more general relevance. The central lesson, which is familiar but not always well advertised, is that physical theories can be empirically established, sometimes with surprising results.

  17. Selected achievements, science directions, and new opportunities for the WEBB Small Watershed Research Program

    Science.gov (United States)

    Pierre D. Glynn; Matthew C. Larsen; Earl A. Greene; Heather L. Buss; David W. Clow; Randall J. Hunt; M. Alisa Mast; Sheila F. Murphy; Norman E. Peters; Stephen D. Sebestyen; James B. Shanley; John F. Walker

    2009-01-01

    Over nearly two decades, the Water, Energy, and Biogeochemical Budgets (WEBB) small watershed research program of the U.S. Geological Survey (USGS) has documented how water and solute fluxes, nutrient, carbon, and mercury dynamics, and weathering and sediment transport respond to natural and humancaused drivers, including climate, climate change, and atmospheric...

  18. Accuracy and Generalizability in Summaries of Affect Regulation Strategies: Comment on Webb, Miles, and Sheeran (2012)

    Science.gov (United States)

    Augustine, Adam A.; Hemenover, Scott H.

    2013-01-01

    In their examination of the effectiveness of affect regulation strategies, Webb, Miles, and Sheeran (2012) offered the results of a broad meta-analysis of studies on regulatory interventions. Their analysis provides an alternative to our earlier, more focused meta-analysis of the affect regulation literature (Augustine & Hemenover, 2009).…

  19. The CFRP primary structure of the MIRI instrument onboard the James Webb Space Telescope

    DEFF Research Database (Denmark)

    Jessen, Niels Christian; Nørgaard-Nielsen, Hans Ulrik; Schroll, J

    2004-01-01

    The design of the Primary Structure of the Mid Infra-Red Instrument (MIRI) onboard the NASA/ESA James Webb Space Telescope will be presented. The main design driver is the energy flow from the 35 K "hot" satellite interface to the 7 K "cold" MIRI interface. Carbon fibre reinforced plastic (CFRP...

  20. Resenha de: Sidney Webb and East Africa: Lavour's Experiment with the doctrine of Native Paramountoy.

    Directory of Open Access Journals (Sweden)

    Antônia Fernanda de Almeida Wright

    1965-03-01

    Full Text Available GREGORY (Robert G.. — Sidney Webb and East Africa. Lavour's' Experiment with the doctrine of Native Paramountoy. University of California Publications in History. Vol. 72, University of California Press, Berkeley and Los Angeles, 1962. Publicação simultânea da Cambridge University Press, London, 1962.

  1. Line of Sight Stabilization of James Webb Space Telescope

    Science.gov (United States)

    Meza, Luis; Tung, Frank; Anandakrishnan, Satya; Spector, Victor; Hyde, Tupper

    2005-01-01

    The James Webb Space Telescope (JWST) builds upon the successful flight experience of the Chandra Xray Telescope by incorporating an additional LOS pointing servo to meet the more stringent pointing requirements. The LOS pointing servo, referred to in JWST as the Fine Guidance Control System (FGCS), will utilize a Fine Guidance Sensor (FGS) as the sensor, and a Fine Steering Mirror (FSM) as the actuator. The FSM is a part of the Optical Telescope Element (OTE) and is in the optical path between the tertiary mirror and the instrument focal plane, while the FGS is part of the Integrated Science Instrument Module (ISIM). The basic Chandra spacecraft bus attitude control and determination architecture, utilizing gyros, star trackers/aspect camera, and reaction wheels, is retained for JWST. This system has achieved pointing stability of better than 0.5 arcseconds. To reach the JWST requirements of milli-arcsecond pointing stability with this ACS hardware, the local FGCS loop is added to the optical path. The FGCS bandwidth is about 2.0 Hz and will therefore attenuate much of the spacecraft ACS induced low frequency jitter. In order to attenuate the higher frequency (greatet than 2.0 Hz) disturbances associated with reaction wheel static and dynamic imbalances, as well as bearing run-out, JWST will employ a two-stage passive vibration isolation system consisting of (1) 7.0 Hz reaction wheel isolators between each reaction wheel and the spacecraft bus, and (2) a 1.0 Hz tower isolator between the spacecraft bus and the Optical Telescope Element (OTE). In order to sense and measure the LOS, the FGS behaves much like an autonomous star tracker that has a very small field of view and uses the optics of the telescope. It performs the functions of acquisition, identification and tracking of stars in its 2.5 x 2.5 arcminute field of view (FOV), and provides the centroid and magnitude of the selected star for use in LOS control. However, since only a single star is being tracked

  2. James Webb Space Telescope Studies of Dark Energy

    Science.gov (United States)

    Gardner, Jonathan P.; Stiavelli, Massimo; Mather, John C.

    2010-01-01

    time-variable source gives the angular diameter distance through measured time delays of multiple images. Finally, the growth of structure can also be constrained by measuring the mass of the largest galaxy clusters over cosmic time. HST has contributed to the study of dark energy through SN1a and gravitational lensing, as discussed above. HST has also helped to characterize galaxy clusters and the HST-measured constraints on the current Hubble constant H(sub 0) are relevant to the interpretation of dark energy measurements (Riess et al 2009a). HST has not been used to constrain BAO as the large number of galaxy redshifts required, of order 100 million, is poorly matched to HST's capabilities. As the successor to HST, the James Webb Space Telescope (JWST; Gardner et al 2006) will continue and extend HST's dark energy work in several ways.

  3. An efficient single-step scheme for manipulating quantum information of two trapped ions beyond the Lamb-Dicke limit

    International Nuclear Information System (INIS)

    Wei, L.F.; Nori, Franco

    2003-01-01

    Based on the exact conditional quantum dynamics for a two-ion system, we propose an efficient single-step scheme for coherently manipulating quantum information of two trapped cold ions by using a pair of synchronous laser pulses. Neither the auxiliary atomic level nor the Lamb-Dicke approximation are needed

  4. Ricardo Guilherme Dicke e o processo de transculturação na l iteratura

    Directory of Open Access Journals (Sweden)

    Adriana Lins Precioso

    2014-01-01

    Full Text Available The article presents a brief overview of the emergence of the cultural studies in England, the concepts of Stuart Hall and the appropriation of these searches by the literary studies, mainly in Latin America represented through the contributions of Ángel R ama. To exemplify this proposal, we analyze excerpts of the short stories „Toada do Esquecido‟ (2006, „Sinfonia equestre‟ (2006, „A proximidade do mar‟ (2011, „O Velho Moço‟ (2011 and „A perseguição‟ (2011, by Ricardo Guilherme Dicke, writer from the state of Mato Grosso, who promotes the dialogue between regional and global issues by the transculturation bias.

  5. Dynamics of coherent states in regular and chaotic regimes of the non-integrable Dicke model

    Science.gov (United States)

    Lerma-Hernández, S.; Chávez-Carlos, J.; Bastarrachea-Magnani, M. A.; López-del-Carpio, B.; Hirsch, J. G.

    2018-04-01

    The quantum dynamics of initial coherent states is studied in the Dicke model and correlated with the dynamics, regular or chaotic, of their classical limit. Analytical expressions for the survival probability, i.e. the probability of finding the system in its initial state at time t, are provided in the regular regions of the model. The results for regular regimes are compared with those of the chaotic ones. It is found that initial coherent states in regular regions have a much longer equilibration time than those located in chaotic regions. The properties of the distributions for the initial coherent states in the Hamiltonian eigenbasis are also studied. It is found that for regular states the components with no negligible contribution are organized in sequences of energy levels distributed according to Gaussian functions. In the case of chaotic coherent states, the energy components do not have a simple structure and the number of participating energy levels is larger than in the regular cases.

  6. Modified Holographic Ricci Dark Energy in Chameleon Brans–Dicke Cosmology and Its Thermodynamic Consequence

    International Nuclear Information System (INIS)

    Jawad, A.; Chattopadhyay, S.; Bhattacharya, S.; Pasqua, A.

    2015-01-01

    The objective of this paper is to discuss the Chameleon Brans–Dicke gravity with non-minimally matter coupling of scalar field. We take modified Holographic Ricci dark energy model in this gravity with its energy density in interaction with energy density of cold dark matter. We assume power-law ansatz for scale factor and scalar field to discuss potential as well as coupling functions in the evolving universe. These reconstructed functions are plotted versus scalar field and time for different values of power component of scale factor n. We observe that potential and coupling functions represent increasing behavior, in particular, consistent results for a specific value of n. Finally, we have examined validity of the generalized second law of thermodynamics and we have observed its validity for all values of n. (paper)

  7. On the limit of Brans-Dicke theory when omega -> infinity

    CERN Document Server

    Chauvineau, B

    2003-01-01

    We discuss the problem of the limit of the Brans-Dicke theory (BDT) in the limit omega -> infinity, when the trace of the stress tensor is not zero. It is shown that a BDT solution, with T not = 0, known in the framework of anisotropic cosmology, fails to converge to the general relativity theory (GRT) corresponding solution. Considering the spherically symmetric field problem, it is shown that the argument leading to the convergence in the static case is lost when the non-static case is considered. These remarks suggest that the non-convergence of BDT to GRT could be the general behaviour, even if T not = 0, except for some (most?) of the highly symmetric solutions, including most of the known ones. The impact on gravitational radiation detection is emphasized.

  8. Spin squeezing as an indicator of quantum chaos in the Dicke model.

    Science.gov (United States)

    Song, Lijun; Yan, Dong; Ma, Jian; Wang, Xiaoguang

    2009-04-01

    We study spin squeezing, an intrinsic quantum property, in the Dicke model without the rotating-wave approximation. We show that the spin squeezing can reveal the underlying chaotic and regular structures in phase space given by a Poincaré section, namely, it acts as an indicator of quantum chaos. Spin squeezing vanishes after a very short time for an initial coherent state centered in a chaotic region, whereas it persists over a longer time for the coherent state centered in a regular region of the phase space. We also study the distribution of the mean spin directions when quantum dynamics takes place. Finally, we discuss relations among spin squeezing, bosonic quadrature squeezing, and two-qubit entanglement in the dynamical processes.

  9. Dynamics of axial symmetric system in self-interacting Brans-Dicke gravity

    International Nuclear Information System (INIS)

    Sharif, M.; Manzoor, Rubab

    2016-01-01

    This paper investigates the dynamics of an axial reflection symmetric model in self-interacting Brans-Dicke gravity for anisotropic fluid. We formulate hydrodynamical equations and discuss oscillations using a time-dependent perturbation for both spin-dependent and spin-independent cases. The expressions of the frequency, the total energy density, and the equation of motion of the oscillating model are obtained. We study the instability of the oscillating models in weak approximations. It is found that the oscillations and stability of the model depend upon the dark energy source along with anisotropy and reflection effects. We conclude that the axial reflection system remains stable for stiffness parameter Γ = 1, collapses for Γ > 1, and becomes unstable for 0 < Γ < 1. (orig.)

  10. Macroscopic Quantum States and Quantum Phase Transition in the Dicke Model

    International Nuclear Information System (INIS)

    Lian Jin-Ling; Zhang Yuan-Wei; Liang Jiu-Qing

    2012-01-01

    The energy spectrum of Dicke Hamiltonians with and without the rotating wave approximation for an arbitrary atom number is obtained analytically by means of the variational method, in which the effective pseudo-spin Hamiltonian resulting from the expectation value in the boson-field coherent state is diagonalized by the spin-coherent-state transformation. In addition to the ground-state energy, an excited macroscopic quantum-state is found corresponding to the south- and north-pole gauges of the spin-coherent states, respectively. Our results of ground-state energies in exact agreement with various approaches show that these models exhibit a zero-temperature quantum phase transition of the second order for any number of atoms, which was commonly considered as a phenomenon of the thermodynamic limit with the atom number tending to infinity. The critical behavior of the geometric phase is analyzed. (general)

  11. Fano and Dicke effects in a double Rashba-ring system

    International Nuclear Information System (INIS)

    Apel, V M; Orellana, P A; Pacheco, M

    2008-01-01

    The electronic transport in a system of two quantum rings side-coupled to a quantum wire is studied via a single-band tunneling tight-binding Hamiltonian. We derived analytical expressions for the conductance and spin polarization when the rings are threaded by magnetic fluxes with Rashba spin-orbit interaction. We show that by using the Fano and Dicke effects this system can be used as an efficient spin filter even for small spin-orbit interaction and small values of magnetic fluxes. We compare the spin-dependent polarization of this design and the polarization obtained with one ring side-coupled to a quantum ring. As a main result, we find better spin polarization capabilities as compared to the one-ring design

  12. Dilatonic Brans-Dicke Anisotropic Collapsing Fluid Sphere And de Broglie Quantum Wave Motion

    International Nuclear Information System (INIS)

    Ghaffarnejad, Hossein

    2016-01-01

    Two dimensional (2D) analogue of vacuum sector of the Brans Dicke (BD) gravity [1] is studied to obtain dynamics of anisotropic spherically symmetric perfect fluid. Our obtained static solutions behave as dark matter with state equation but in non-static regimes behave as regular perfect fluid with barotropic index ϒ > 0. Positivity property of total mass of the fluid causes that the BD parameter to be ω >2/3 and/or ω 0 the apparent horizon is covered by event horizon where the cosmic censorship hypothesis is still valid. According to the model [1], we obtain de Broglie pilot wave of our metric solution which describes particles ensemble which become distinguishable via different values of ω . Incident current density of particles ensemble on the horizons is evaluated which describe the ‘Hawking radiation’. The de Brogle-Bohm quantum potential effect is calculated also on the event (apparent) horizon which is independent (dependent) to values of ω . (paper)

  13. Modified Holographic Ricci Dark Energy in Chameleon Brans-Dicke Cosmology and Its Thermodynamic Consequence

    Science.gov (United States)

    Jawad, A.; Chattopadhyay, S.; Bhattacharya, S.; Pasqua, A.

    2015-04-01

    The objective of this paper is to discuss the Chameleon Brans-Dicke gravity with non-minimally matter coupling of scalar field. We take modified Holographic Ricci dark energy model in this gravity with its energy density in interaction with energy density of cold dark matter. We assume power-law ansatz for scale factor and scalar field to discuss potential as well as coupling functions in the evolving universe. These reconstructed functions are plotted versus scalar field and time for different values of power component of scale factor n. We observe that potential and coupling functions represent increasing behavior, in particular, consistent results for a specific value of n. Finally, we have examined validity of the generalized second law of thermodynamics and we have observed its validity for all values of n. The financial Supported from Department of Science and Technology, Govt. of India under Project Grant No. SR/FTP/PS-167/2011 is thankfully acknowledged by SC

  14. Dynamics of axial symmetric system in self-interacting Brans-Dicke gravity

    Energy Technology Data Exchange (ETDEWEB)

    Sharif, M. [University of the Punjab, Department of Mathematics, Lahore (Pakistan); Manzoor, Rubab [University of Management and Technology, Department of Mathematics, Lahore (Pakistan)

    2016-06-15

    This paper investigates the dynamics of an axial reflection symmetric model in self-interacting Brans-Dicke gravity for anisotropic fluid. We formulate hydrodynamical equations and discuss oscillations using a time-dependent perturbation for both spin-dependent and spin-independent cases. The expressions of the frequency, the total energy density, and the equation of motion of the oscillating model are obtained. We study the instability of the oscillating models in weak approximations. It is found that the oscillations and stability of the model depend upon the dark energy source along with anisotropy and reflection effects. We conclude that the axial reflection system remains stable for stiffness parameter Γ = 1, collapses for Γ > 1, and becomes unstable for 0 < Γ < 1. (orig.)

  15. Notes on the post-Newtonian limit of the massive Brans-Dicke theory

    Energy Technology Data Exchange (ETDEWEB)

    Roshan, Mahmood; Shojai, Fatimah, E-mail: fshojai@ut.ac.ir [Department of Physics, University of Tehran, Tehran (Iran, Islamic Republic of)

    2011-07-21

    We consider the post-Newtonian limit of the massive Brans-Dicke theory and make some notes about the post-Newtonian limit of the case {omega} = 0. This case is dynamically equivalent to the metric f(R) theory. It is known that this theory can be compatible with the solar system tests if the Chameleon mechanism occurs. Also, it is known that this mechanism is because of the nonlinearity in the field equations produced by the largeness of the local curvature relative to the background curvature. Thus, the linearization of the field equations breaks down. On the other hand, we know that the Chameleon mechanism exists when a coupling between the matter and the scalar field exists. In the Jordan frame of the Brans-Dicke theory, we have no such coupling. But in the Einstein frame, this theory behaves like a Chameleon scalar field. By confining ourselves to the case {omega} = 0, we show that 'Chameleon-like' behaviour can exist also in the Jordan frame, but it has an important difference compared with the Chameleon mechanism. Also we show that the conditions which lead to the existence of a 'Chameleon-like' mechanism are consistent with the conditions in the post-Newtonian limit which correspond to a heavy scalar field at the cosmological scale and a small effective cosmological constant. Thus, one can linearize field equations to the post-Newtonian order, and this linearization has no contradiction with the existence of 'Chameleon-like' behaviour.

  16. O absurdo em «Caieira», de Ricardo Guilherme Dicke

    Directory of Open Access Journals (Sweden)

    Hilda Gomes Dutra Magalhães

    2012-08-01

    Full Text Available Resumo: Nosso objetivo neste artigo consiste em analisar o espaço do absurdo no romance Caieira, do escritor matogrossense Ricardo Guilherme Dicke. Como suporte teóricometodológico, utilizamos as ideias sobre o absurdo de Camus. Durante a análise, percebemos que o espaço em que se desenvolvem as ações narradas em Caieira representa uma relação de dominação, em que os personagens são reduzidas a fantasmas ou objetos, presas num mundo de cal, árido de humanidade. Mesmo quando o personagem principal tenta reverter o quadro, acaba se transformando num reverso da mesma moeda, repetindo o modelo de dominação contra o qual se insurge, reeditando um ciclo de poder e dominação. Palavras-chave: Literatura brasileira; análise literária; absurdo; espaço.Abstract: Our aim in this paper is to analyze the space of the absurd at the novel Caieira, by Ricardo Guilherme Dicke, writer from Mato Grosso. As a theoretical-methodological support, we use the ideas of on the absurd presented by Camus. During the analysis, we find that the space in which the actions narrated in Caieira develop represents a relationship of domination, in which the characters are reduced to objects or ghosts, trapped in a world of lime, arid of humanity. Even when the main character tries to reverse the situation, eventually becoming a reverse of the same coin, repeating the pattern of domination against which it protests, reissuing a cycle of power and domination. Keywords: Brazilian literature; literary analysis; absurd; space.

  17. Critical Science Instrument Alignment of the James Webb Space Telescope (JWST) Integrated Science Instrument Module (ISIM)

    Science.gov (United States)

    Rohrbach, Scott O.; Kubalak, David A.; Gracey, Renee M.; Sabatke, Derek S.; Howard, Joseph M.; Telfer, Randal C.; Zielinski, Thomas P.

    2016-01-01

    This paper describes the critical instrument alignment terms associated with the six-degree of freedom alignment of each the Science Instrument (SI) in the James Webb Space Telescope (JWST), including focus, pupil shear, pupil clocking, and boresight. We present the test methods used during cryogenic-vacuum tests to directly measure the performance of each parameter, the requirements levied on each, and the impact of any violations of these requirements at the instrument and Observatory level.

  18. Matlab based Toolkits used to Interface with Optical Design Software for NASA's James Webb Space Telescope

    Science.gov (United States)

    Howard, Joseph

    2007-01-01

    The viewgraph presentation provides an introduction to the James Webb Space Telescope (JWST). The first part provides a brief overview of Matlab toolkits including CodeV, OSLO, and Zemax Toolkits. The toolkit overview examines purpose, layout, how Matlab gets data from CodeV, function layout, and using cvHELP. The second part provides examples of use with JWST, including wavefront sensitivities and alignment simulations.

  19. Isotropic LQC and LQC-inspired models with a massless scalar field as generalised Brans-Dicke theories

    Science.gov (United States)

    Rama, S. Kalyana

    2018-06-01

    We explore whether generalised Brans-Dicke theories, which have a scalar field Φ and a function ω (Φ ), can be the effective actions leading to the effective equations of motion of the LQC and the LQC-inspired models, which have a massless scalar field σ and a function f( m). We find that this is possible for isotropic cosmology. We relate the pairs (σ , f) and (Φ , ω ) and, using examples, illustrate these relations. We find that near the bounce of the LQC evolutions for which f(m) = sin m, the corresponding field Φ → 0 and the function ω (Φ ) ∝ Φ ^2. We also find that the class of generalised Brans-Dicke theories, which we had found earlier to lead to non singular isotropic evolutions, may be written as an LQC-inspired model. The relations found here in the isotropic cases do not apply to the anisotropic cases, which perhaps require more general effective actions.

  20. Interaction of Gravitational field and Brans-Dicke field in R/W universe containing Dark Energy like fluid

    International Nuclear Information System (INIS)

    Singh, Kangujam Priyokumar; Dewri, Mukunda; Singh, Koijam Manihar

    2016-01-01

    On studying some new models of Robertson-Walker universes with a Brans-Dicke scalar field, it is found that most of these universes contain a dark energy like fluid which confirms the present scenario of the expansion of the universe. In one of the cases, the exact solution of the field equations gives a universe with a false vacuum, while in another it reduces to that of dust distribution in the Brans-Dicke cosmology when the cosmological constant is not in the picture. In one particular model it is found that the universe may undergo a Big Rip in the future, and thus it will be very interesting to investigate such models further. (paper)

  1. Stationary axially symmetric exterior solutions in the five-dimensional representation of the Brans-Dicke-Jordan theory of gravitation

    International Nuclear Information System (INIS)

    Bruckman, W.

    1986-01-01

    The inverse scattering method of Belinsky and Zakharov is used to investigate axially symmetric stationary vacuum soliton solutions in the five-dimensional representation of the Brans-Dicke-Jordan theory of gravitation, where the scalar field of the theory is an element of a five-dimensional metric. The resulting equations for the spacetime metric are similar to those of solitons in general relativity, while the scalar field generated is the product of a simple function of the coordinates and an already known scalar field solution. A family of solutions is considered that reduce, in the absence of rotation, to the five-dimensional form of a well-known Weyl-Levi Civita axially symmetric static vacuum solution. With a suitable choice of parameters, this static limit becomes equivalent to the spherically symmetric solution of the Brans-Dicke theory. An exact metric, in which the Kerr-scalar McIntosh solution is a special case, is given explicitly

  2. Anisotropic string cosmological model in Brans–Dicke theory of gravitation with time-dependent deceleration parameter

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, D. Ch., E-mail: dcmaurya563@gmail.com; Zia, R., E-mail: rashidzya@gmail.com; Pradhan, A., E-mail: pradhan.anirudh@gmail.com [GLA University, Department of Mathematics, Institute of Applied Sciences and Humanities (India)

    2016-10-15

    We discuss a spatially homogeneous and anisotropic string cosmological models in the Brans–Dicke theory of gravitation. For a spatially homogeneous metric, it is assumed that the expansion scalar θ is proportional to the shear scalar σ. This condition leads to A = kB{sup m}, where k and m are constants. With these assumptions and also assuming a variable scale factor a = a(t), we find solutions of the Brans–Dicke field equations. Various phenomena like the Big Bang, expanding universe, and shift from anisotropy to isotropy are observed in the model. It can also be seen that in early stage of the evolution of the universe, strings dominate over particles, whereas the universe is dominated by massive strings at the late time. Some physical and geometrical behaviors of the models are also discussed and observed to be in good agreement with the recent observations of SNe la supernovae.

  3. Exact solution for the inhomogeneous Dicke model in the canonical ensemble: Thermodynamical limit and finite-size corrections

    Energy Technology Data Exchange (ETDEWEB)

    Pogosov, W.V., E-mail: walter.pogosov@gmail.com [N.L. Dukhov All-Russia Research Institute of Automatics, Moscow (Russian Federation); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny (Russian Federation); Shapiro, D.S. [N.L. Dukhov All-Russia Research Institute of Automatics, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny (Russian Federation); V.A. Kotel' nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Moscow (Russian Federation); National University of Science and Technology MISIS, Moscow (Russian Federation); Bork, L.V. [N.L. Dukhov All-Russia Research Institute of Automatics, Moscow (Russian Federation); Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Onishchenko, A.I. [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny (Russian Federation); Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow (Russian Federation)

    2017-06-15

    We consider an exactly solvable inhomogeneous Dicke model which describes an interaction between a disordered ensemble of two-level systems with single mode boson field. The existing method for evaluation of Richardson–Gaudin equations in the thermodynamical limit is extended to the case of Bethe equations in Dicke model. Using this extension, we present expressions both for the ground state and lowest excited states energies as well as leading-order finite-size corrections to these quantities for an arbitrary distribution of individual spin energies. We then evaluate these quantities for an equally-spaced distribution (constant density of states). In particular, we study evolution of the spectral gap and other related quantities. We also reveal regions on the phase diagram, where finite-size corrections are of particular importance.

  4. Resonances of the confined hydrogen atom and the Lamb-Dicke effect in non-relativistic qed

    DEFF Research Database (Denmark)

    Faupin, Jeremy

    2008-01-01

    We study a model describing a system of one dynamical nucleus and one electron confined by their center of mass and interacting with the quantized electromagnetic field. We impose an ultraviolet cutoff and assume that the fine-structure constant is sufficiently small. Using a renormalization grou...... method (based on [3, 4]), we prove that the unperturbed eigenvalues turn into resonances when the nucleus and the electron are coupled to the radiation field. This analysis is related to the Lamb–Dicke effect....

  5. New holographic reconstruction of scalar-field dark-energy models in the framework of chameleon Brans-Dicke cosmology

    International Nuclear Information System (INIS)

    Chattopadhyay, Surajit; Pasqua, Antonio; Khurshudyan, Martiros

    2014-01-01

    Motivated by the work of Yang et al. (Mod. Phys. Lett. A 26:191, 2011), we report on a study of the new holographic dark energy (NHDE) model with energy density given by ρ D = (3φ 2 )/(4ω)(μH 2 + νH) in the framework of chameleon Brans-Dicke cosmology. We have studied the correspondence between the quintessence, the DBI-essence, and the tachyon scalar-field models with the NHDE model in the framework of chameleon Brans-Dicke cosmology. Deriving an expression of the Hubble parameter H and, accordingly, ρ D in the context of chameleon Brans-Dicke chameleon cosmology, we have reconstructed the potentials and dynamics for these scalar-field models. Furthermore, we have examined the stability for the obtained solutions of the crossing of the phantom divide under a quantum correction of massless conformally invariant fields, and we have seen that the quantum correction could be small when the phantom crossing occurs and the obtained solutions of the phantom crossing could be stable under the quantum correction. It has also been noted that the potential increases as the matter. chameleon coupling gets stronger with the evolution of the universe. (orig.)

  6. New holographic reconstruction of scalar-field dark-energy models in the framework of chameleon Brans-Dicke cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, Surajit [Pailan College of Management and Technology, Kolkata (India); Pasqua, Antonio [University of Trieste, Department of Physics, Trieste (Italy); Khurshudyan, Martiros [Yerevan State University, Department of Theoretical Physics, Yerevan (Armenia); Potsdam-Golm Science Park, Max Planck Institute of Colloids and Interfaces, Potsdam (Germany)

    2014-09-15

    Motivated by the work of Yang et al. (Mod. Phys. Lett. A 26:191, 2011), we report on a study of the new holographic dark energy (NHDE) model with energy density given by ρ{sub D} = (3φ{sup 2})/(4ω)(μH{sup 2} + νH) in the framework of chameleon Brans-Dicke cosmology. We have studied the correspondence between the quintessence, the DBI-essence, and the tachyon scalar-field models with the NHDE model in the framework of chameleon Brans-Dicke cosmology. Deriving an expression of the Hubble parameter H and, accordingly, ρ{sub D} in the context of chameleon Brans-Dicke chameleon cosmology, we have reconstructed the potentials and dynamics for these scalar-field models. Furthermore, we have examined the stability for the obtained solutions of the crossing of the phantom divide under a quantum correction of massless conformally invariant fields, and we have seen that the quantum correction could be small when the phantom crossing occurs and the obtained solutions of the phantom crossing could be stable under the quantum correction. It has also been noted that the potential increases as the matter. chameleon coupling gets stronger with the evolution of the universe. (orig.)

  7. Quantum signature of chaos and thermalization in the kicked Dicke model

    Science.gov (United States)

    Ray, S.; Ghosh, A.; Sinha, S.

    2016-09-01

    We study the quantum dynamics of the kicked Dicke model (KDM) in terms of the Floquet operator, and we analyze the connection between chaos and thermalization in this context. The Hamiltonian map is constructed by suitably taking the classical limit of the Heisenberg equation of motion to study the corresponding phase-space dynamics, which shows a crossover from regular to chaotic motion by tuning the kicking strength. The fixed-point analysis and calculation of the Lyapunov exponent (LE) provide us with a complete picture of the onset of chaos in phase-space dynamics. We carry out a spectral analysis of the Floquet operator, which includes a calculation of the quasienergy spacing distribution and structural entropy to show the correspondence to the random matrix theory in the chaotic regime. Finally, we analyze the thermodynamics and statistical properties of the bosonic sector as well as the spin sector, and we discuss how such a periodically kicked system relaxes to a thermalized state in accordance with the laws of statistical mechanics.

  8. The Brans-Dicke gravity as a theory of dark matter

    International Nuclear Information System (INIS)

    Kim, Hongsu

    2010-01-01

    The pure Brans-Dicke (BD) gravity with or without the cosmological constant Λ has been taken as a model theory for dark matter. Indeed, there has been a consensus that unless one modifies either the standard theory of gravity, namely, general relativity, or the standard model for particle physics, or both, one can never achieve a satisfying understanding of the phenomena associated with dark matter and dark energy. Along this line, our dark matter model in this work can be thought of as an attempt to modify the gravity side alone in the simplest fashion to achieve the goal. Among others, it is demonstrated that our model theory can successfully predict the emergence of a dark matter halo-like configuration in terms of a self-gravitating spacetime solution to the BD field equations and reproduce the flattened rotation curve in this dark halo-like object in terms of the non-trivial energy density of the BD scalar field, which was absent in the context of general relativity, where Newton's constant is strictly a 'constant' having no dynamics. Our model theory, however, is not entirely without flaw, such as the prediction of relativistic jets in all types of galaxies, which actually is not the case.

  9. Lacan Leitor de Melanie Klein: O Caso Dick em Questão

    Directory of Open Access Journals (Sweden)

    Ariana Lucero

    Full Text Available RESUMO O artigo apresenta a leitura que Jacques Lacan faz do caso Dick, de Melanie Klein. Para tanto, a discussão com o filósofo Jean Hyppolite é retomada com o objetivo de explicitarmos como os mecanismos de Ausstossung [expulsão], Verneinung [negação] e Bejahung [afirmação], descritos por Freud em 1925, podem contribuir para a compreensão da constituição psíquica sob uma perspectiva lacaniana. Em seguida, expomos o caso, tanto para apreendermos clinicamente o que foi exposto na teoria, quanto para evidenciarmos como Lacan se distancia da concepção de fantasia de M. Klein. O tema do diagnóstico, no entanto, aparece em ambos ligado a uma forma de organização subjetiva ainda em constituição na infância, o que traz elementos para refletirmos sobre essa questão na atualidade.

  10. Eternal extended inflation and graceful exit from old inflation without Jordan-Brans-Dicke

    Science.gov (United States)

    Linde, Andrei

    1990-10-01

    Recently a possible solution to the graceful exit problem of the old inflation was proposed in the context of the Jordan-Brans-Dicke theory (extended inflation). In this paper we will argue that inflation in this theory occurs in a most natural way if it starts near the Planck density, as in the standard version of chaotic inflation. With most natural initial conditions, the inflationary universe in the JBD theory enters the stage of permanent reproduction of new inflationary domains (eternal extended inflation). In order to realize the extended inflation scenario at least two classical scalar fields driving inflation are necessary, as distinct from the simplest versions of new and chaotic inflation. It is shown that in the theory of two scalar fields one can solve the graceful exit problem even without modifying the Einstein gravity theory, due to the possibility that the decay rate of the false rate vacuum in old inflation depends on the value of the second scalar field and hence on time. Address after 1 September 1990: Physics Department, Stanford University, Varian Building, Stanford, CA 94305, USA.

  11. Quantum phase transitions of light in a dissipative Dicke-Bose-Hubbard model

    Science.gov (United States)

    Wu, Ren-Cun; Tan, Lei; Zhang, Wen-Xuan; Liu, Wu-Ming

    2017-09-01

    The impact that the environment has on the quantum phase transition of light in the Dicke-Bose-Hubbard model is investigated. Based on the quasibosonic approach, mean-field theory, and perturbation theory, the formulation of the Hamiltonian, the eigenenergies, and the superfluid order parameter are obtained analytically. Compared with the ideal cases, the order parameter of the system evolves with time as the photons naturally decay in their environment. When the system starts with the superfluid state, the dissipation makes the photons more likely to localize, and a greater hopping energy of photons is required to restore the long-range phase coherence of the localized state of the system. Furthermore, the Mott lobes depend crucially on the numbers of atoms and photons (which disappear) of each site, and the system tends to be classical with the number of atoms increasing; however, the atomic number is far lower than that expected under ideal circumstances. As there is an inevitable interaction between the coupled-cavity array and its surrounding environment in the actual experiments, the system is intrinsically dissipative. The results obtained here provide a more realistic image for characterizing the dissipative nature of quantum phase transitions in lossy platforms, which will offer valuable insight into quantum simulation of a dissipative system and which are helpful in guiding experimentalists in open quantum systems.

  12. Shear-free axial model in massive Brans–Dicke gravity

    Energy Technology Data Exchange (ETDEWEB)

    Sharif, M., E-mail: msharif.math@pu.edu.pk [Department of Mathematics, University of the Punjab, Quaid-e-Azam Campus, Lahore-54590 (Pakistan); Manzoor, Rubab, E-mail: rubab.manzoor@umt.edu.pk [Department of Mathematics, University of the Punjab, Quaid-e-Azam Campus, Lahore-54590 (Pakistan); Department of Mathematics, University of Management and Technology, Johar Town Campus, Lahore-54782 (Pakistan)

    2017-01-15

    This paper explores the influences of dark energy on the shear-free axially symmetric evolution by considering self-interacting Brans–Dicke gravity as a dark energy candidate. We describe energy source of the model and derive all the effective dynamical variables as well as effective structure scalars. It is found that scalar field is one of the sources of anisotropy and dissipation. The resulting effective structure scalars help to study the dynamics associated with dark energy in any axial configuration. In order to investigate shear-free evolution, we formulate a set of governing equations along with heat transport equation. We discuss consequences of shear-free condition upon different SBD fluid models like dissipative non-geodesic and geodesic models. For dissipative non-geodesic case, the rotational distribution turns out to be the necessary and sufficient condition for radiating model. The dissipation depends upon inhomogeneous expansion. The geodesic model is found to be irrotational and non-radiating. The non-dissipative geodesic model leads to FRW model for positive values of the expansion parameter.

  13. Eternal extended inflation and graceful exit from old inflation without Jordan-Brans-Dicke

    International Nuclear Information System (INIS)

    Linde, A.

    1990-01-01

    Recently a possible solution to the graceful exit problem of the old inflation was proposed in the context of the Jordan-Brans-Dicke theory (extended inflation). In this paper we will argue that inflation in this theory occurs in a most natural way if it starts near the Planck density, as in the standard version of chaotic inflation. With most natural initial conditions, the inflationary universe in the JBD theory enters the stage of permanent reproduction of new inflationary domains (eternal extended inflation). In order to realize the extended inflation scenario at least two classical scalar fields driving inflation are necessary, as distinct from the simplest versions of new and chaotic inflation. It is shown that in the theory of two scalar fields one can solve the graceful exit problem even without modifying the Einstein gravity theory, due to the possibility that the decay rate of the false vacuum in old inflation depends on the value of the second scalar field and hence on time. (orig.)

  14. Pathways Towards Habitable Planets: Capabilities of the James Webb Space Telescope

    Science.gov (United States)

    Clampin, Mark

    2009-01-01

    The James Webb Space Telescope (JWST) is a large aperture (6.5 meter), cryogenic space telescope with a suite of near and mid-infrared instruments covering the wavelength range of 0.6 m to 28 m. JWST s primary science goal is to detect and characterize the first galaxies. It will also study the assembly of galaxies, star formation, and the formation of evolution of planetary systems. We also review the expected scientific performance of the observatory for observations of exosolar planets by means of transit photometry and spectroscopy, and direct coronagraphic imaging and address its role in the search for habitable planets.

  15. Cryo-Vacuum Testing of the Integrated Science Instrument Module for the James Webb Space Telescope

    Science.gov (United States)

    Kimble, Randy A.; Davila, P. S.; Drury, M. P.; Glazer, S. D.; Krom, J. R.; Lundquist, R. A.; Mann, S. D.; McGuffey, D. B.; Perry, R. L.; Ramey, D. D.

    2011-01-01

    With delivery of the science instruments for the James Webb Space Telescope (JWST) to Goddard Space Flight Center (GSFC) expected in 2012, current plans call for the first cryo-vacuum test of the Integrated Science Instrument Module (ISIM) to be carried out at GSFC in early 2013. Plans are well underway for conducting this ambitious test, which will perform critical verifications of a number of optical, thermal, and operational requirements of the IS 1M hardware, at its deep cryogenic operating temperature. We describe here the facilities, goals, methods, and timeline for this important Integration & Test milestone in the JWST program.

  16. The Mid-Infrared Instrument for the James Webb Space Telescope, I: Introduction

    DEFF Research Database (Denmark)

    Rieke, G. H.; Wright, G. S.; Böker, T.

    2015-01-01

    MIRI (the Mid-Infrared Instrument for the James Webb Space Telescope [JWST]) operates from 5 to 28: 5 μm and combines over this range: (1) unprecedented sensitivity levels; (2) subarcsecond angular resolution; (3) freedom from atmospheric interference; (4) the inherent stability of observing...... in space; and (5) a suite of versatile capabilities including imaging, low- and medium-resolution spectroscopy (with an integral field unit), and coronagraphy. We illustrate the potential uses of this unique combination of capabilities with various science examples: (1) imaging exoplanets; (2) transit...

  17. The Mid-Infrared Instrument for the James Webb Space Telescope, II: Design and Build

    DEFF Research Database (Denmark)

    Wright, G. S.; Wright, David; Goodson, G. B.

    2015-01-01

    The Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) provides measurements over the wavelength range 5 to 28: 5 µm. MIRI has, within a single "package," four key scientific functions: photometric imaging, coronagraphy, single-source low-spectral resolving power (R similar...... in terms of the "as-built" instrument. It also describes the test program that led to delivery of the tested and calibrated Flight Model to NASA in 2012, and the confirmation after delivery of the key interface requirements....

  18. System Definition of the James Webb Space Telescope (JWST) Integrated Science Instrument Module (ISIM)

    Science.gov (United States)

    Lundquist, Ray; Aymergen, Cagatay; VanCampen, Julie; Abell, James; Smith, Miles; Driggers, Phillip

    2008-01-01

    The Integrated Science Instrument Module (ISIM) for the James Webb Space Telescope (JWST) provides the critical functions and the environment for the four science instruments on JWST. This complex system development across many international organizations presents unique challenges and unique solutions. Here we describe how the requirement flow has been coordinated through the documentation system, how the tools and processes are used to minimize impact to the development of the affected interfaces, how the system design has matured, how the design review process operates, and how the system implementation is managed through reporting to ensure a truly world class scientific instrument compliment is created as the final product.

  19. Arsenic Removal from Drinking Water by Adsorptive Media U.S. EPA Demonstration Project at Webb Consolidated Independent School District in Bruni, TX - Final Performance Evaluation Report

    Science.gov (United States)

    This report documents the activities performed and the results obtained from the arsenic removal treatment technology demonstration project at the Webb Consolidated Independent School District (Webb CISD) in Bruni, TX. The main objective of the project was to evaluate the effect...

  20. The Former Miss Barstow with every Tom, Dick and Harry in a doll's house

    Directory of Open Access Journals (Sweden)

    Richard Newton

    2015-02-01

    Full Text Available Julie Holledge, panel chairperson and member of the International Ibsen Committee, invited myself along with 3 others to participate in the Inaugural Artists’ Keynote Panel: Applied Ibsen on Four Continents: The Artists’ Intentions. My presentation focused on “The Former Miss Barstow with every Tom, Dick and Harry in a doll’s house.” This was an adaptation of Ibsen’s “A Doll’s House” produced and staged in Los Angeles, California, 1987.  For the XIIIth International Ibsen Conference at the University of Tromsø, Norway, I projected images; a few found on the internet, and many from the production itself, as well as a video clip shown streaming live from YouTube. The article describes the social context of the 80s, analyzes the reinterpretation of Ibsen’s characters, and sets out to explain the symbology of the sets and costumes. I also touch on the differences between this production and Ibsen’s original in four important aspects. These would be the macaroons, the Tarantella, the silk stockings and the end of the play. Finally, I explain my decision to upload this version of “A Doll’s House,’ scene by scene, to my page on YouTube. Having shown films and videos for many years at festivals around the globe, I was looking for a way to step outside that box and reach an international audience just beyond my keyboard. In all of these ways, the goal has been to illuminate the ways in which an artist takes Ibsen’s text and applies it to the specific social context of their time and culture.

  1. A nearly cylindrically symmetric source in Brans-Dicke gravity as the generator of the rotational curves of the galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Santos, S.M. dos [Universidade Estadual Paulista Julio de Mesquita Filho-UNESP, Guaratingueta, SP (Brazil); Instituto Federal de Educacao, Ciencia e Tecnologia do Rio Grande do Sul-IFRS, Porto Alegre, RS (Brazil); Silva, J.M.H. da [Universidade Estadual Paulista Julio de Mesquita Filho-UNESP, Guaratingueta, SP (Brazil); Guimaraes, M.E.X. [Universidade Federal Fluminense-UFF, Instituto de Fisica, Niteroi, RJ (Brazil); Neto, J.L. [Universidade Federal do Rio de Janeiro-UFRJ, Instituto de Fisica, Rio de Janeiro, RJ (Brazil)

    2017-12-15

    Observation shows that the velocities of stars grow by approximately 2-3 orders of magnitude when the distances from the centers of the galaxies are in the range of 0.5-82.3 kpc, before they begin to tend to a constant value. Up to now, the reason for this behavior is still a matter for debate. In this work, we propose a model which adequately describes this unusual behavior using a (nearly) cylindrical symmetrical solution in the framework of a scalar-tensor-like (the Brans-Dicke model) theory of gravity. (orig.)

  2. On the emergence of the ΛCDM model from self-interacting Brans-Dicke theory in d = 5

    Energy Technology Data Exchange (ETDEWEB)

    Reyes, Luz Marina [CUCEI, Universidad de Guadalajara, Departamento de Ciencias Computacionales, Guadalajara (Mexico); Perez Bergliaffa, Santiago Esteban [Universidade do Estado do Rio de Janeiro, Departamento de Fisica Teorica, Instituto de Fisica, Rio de Janeiro (Brazil)

    2018-01-15

    We investigate whether a self-interacting Brans-Dicke theory in d = 5 without matter and with a time-dependent metric can describe, after dimensional reduction to d = 4, the FLRW model with accelerated expansion and non-relativistic matter. By rewriting the effective 4-dimensional theory as an autonomous 3-dimensional dynamical system and studying its critical points, we show that the ΛCDM cosmology cannot emerge from such a model. This result suggests that a richer structure in d = 5 may be needed to obtain the accelerated expansion as well as the matter content of the 4-dimensional universe. (orig.)

  3. On the emergence of the ΛCDM model from self-interacting Brans-Dicke theory in d= 5

    Science.gov (United States)

    Reyes, Luz Marina; Perez Bergliaffa, Santiago Esteban

    2018-01-01

    We investigate whether a self-interacting Brans-Dicke theory in d=5 without matter and with a time-dependent metric can describe, after dimensional reduction to d=4, the FLRW model with accelerated expansion and non-relativistic matter. By rewriting the effective 4-dimensional theory as an autonomous 3-dimensional dynamical system and studying its critical points, we show that the ΛCDM cosmology cannot emerge from such a model. This result suggests that a richer structure in d=5 may be needed to obtain the accelerated expansion as well as the matter content of the 4-dimensional universe.

  4. A nearly cylindrically symmetric source in Brans-Dicke gravity as the generator of the rotational curves of the galaxies

    Science.gov (United States)

    dos Santos, S. Mittmann; da Silva, J. M. Hoff; Guimarães, M. E. X.; Neto, J. L.

    2017-12-01

    Observation shows that the velocities of stars grow by approximately 2-3 orders of magnitude when the distances from the centers of the galaxies are in the range of 0.5-82.3 kpc, before they begin to tend to a constant value. Up to now, the reason for this behavior is still a matter for debate. In this work, we propose a model which adequately describes this unusual behavior using a (nearly) cylindrical symmetrical solution in the framework of a scalar-tensor-like (the Brans-Dicke model) theory of gravity.

  5. Study of Antigravity in an F(R) Model and in Brans-Dicke Theory with Cosmological Constant

    OpenAIRE

    Oikonomou, V. K.; Karagiannakis, N.

    2014-01-01

    We study antigravity, that is having an effective gravitational constant with a negative sign, in scalar-tensor theories originating from $F(R)$-theory and in a Brans-Dicke model with cosmological constant. For the $F(R)$ theory case, we obtain the antigravity scalar-tensor theory in the Jordan frame by using a variant of the Lagrange multipliers method and we numerically study the time dependent effective gravitational constant. As we shall demonstrate by using a specific $F(R)$ model, altho...

  6. Taxonomy of the Oriental leafhopper genus Favintiga Webb (Hemiptera: Cicadellidae: Deltocephalinae: Drabescini) with description of a new species from China.

    Science.gov (United States)

    Lu, Lin; Zhang, Yalin

    2018-01-12

    The Oriental leafhopper genus Favintiga Webb is reviewed. A checklist to the species is provided together with a key for their separation. The genus contains three species: F. camphorae (Matsumura), F. gracilipenis Shang Zhang and F. paragracilipenis sp. nov., the latter described here from the Jianfengling Mountains, Hainan, China.

  7. Cryogenic Photogrammetry and Radiometry for the James Webb Space Telescope Microshutters

    Science.gov (United States)

    Chambers, Victor J.; Morey, Peter A.; Zukowski, Barbara J.; Kutyrev, Alexander S.; Collins, Nicholas R.

    2012-01-01

    The James Webb Space Telescope (JWST) relies on several innovations to complete its five year mission. One vital technology is microshutters, the programmable field selectors that enable the Near Infrared Spectrometer (NIRSpec) to perform multi-object spectroscopy. Mission success depends on acquiring spectra from large numbers of galaxies by positioning shutter slits over faint targets. Precise selection of faint targets requires field selectors that are both high in contrast and stable in position. We have developed test facilities to evaluate microshutter contrast and alignment stability at their 35K operating temperature. These facilities used a novel application of image registration algorithms to obtain non-contact, sub-micron measurements in cryogenic conditions. The cryogenic motion of the shutters was successfully characterized. Optical results also demonstrated that shutter contrast far exceeds the NIRSpec requirements. Our test program has concluded with the delivery of a flight-qualified field selection subsystem to the NIRSpec bench.

  8. James Webb Space Telescope Observations of Stellar Occultations by Solar System Bodies and Rings

    Science.gov (United States)

    Santos-Sanz, P.; French, R. G.; Pinilla-Alonso, N.; Stansberry, J.; Lin, Z-Y.; Zhang, Z-W.; Vilenius, E.; Mueller, Th.; Ortiz, J. L.; Braga-Ribas, F.; hide

    2016-01-01

    In this paper, we investigate the opportunities provided by the James Webb Space Telescope (JWST) for significant scientific advances in the study of Solar System bodies and rings using stellar occultations. The strengths and weaknesses of the stellar occultation technique are evaluated in light of JWST's unique capabilities. We identify several possible JWST occultation events by minor bodies and rings and evaluate their potential scientific value. These predictions depend critically on accurate a priori knowledge of the orbit of JWST near the Sun–Earth Lagrange point 2 (L2). We also explore the possibility of serendipitous stellar occultations by very small minor bodies as a byproduct of other JWST observing programs. Finally, to optimize the potential scientific return of stellar occultation observations, we identify several characteristics of JWST's orbit and instrumentation that should be taken into account during JWST's development.

  9. Standardization of XML Database Exchanges and the James Webb Space Telescope Experience

    Science.gov (United States)

    Gal-Edd, Jonathan; Detter, Ryan; Jones, Ron; Fatig, Curtis C.

    2007-01-01

    Personnel from the National Aeronautics and Space Administration (NASA) James Webb Space Telescope (JWST) Project have been working with various standard communities such the Object Management Group (OMG) and the Consultative Committee for Space Data Systems (CCSDS) to assist in the definition of a common extensible Markup Language (XML) for database exchange format. The CCSDS and OMG standards are intended for the exchange of core command and telemetry information, not for all database information needed to exercise a NASA space mission. The mission-specific database, containing all the information needed for a space mission, is translated from/to the standard using a translator. The standard is meant to provide a system that encompasses 90% of the information needed for command and telemetry processing. This paper will discuss standardization of the XML database exchange format, tools used, and the JWST experience, as well as future work with XML standard groups both commercial and government.

  10. The James Webb Space Telescope's Near-Infrared Camera (NIRCam): Making Models, Building Understanding

    Science.gov (United States)

    McCarthy, D. W., Jr.; Lebofsky, L. A.; Higgins, M. L.; Lebofsky, N. R.

    2011-09-01

    Since 2003, the Near Infrared Camear (NIRCam) science team for the James Webb Space Telescope (JWST) has conducted "Train the Trainer" workshops for adult leaders of the Girl Scout of the USA (GSUSA), engaging them in the process of scientific inquiry and equipping them to host astronomy-related activities at the troop level. Training includes topics in basic astronomy (night sky, phases of the Moon, the scale of the Solar System and beyond, stars, galaxies, telescopes, etc.) as well as JWST-specific research areas in extra-solar planetary systems and cosmology, to pave the way for girls and women to understand the first images from JWST. Participants become part of our world-wide network of 160 trainers teaching young women essential STEM-related concepts using astronomy, the night sky environment, applied math, engineering, and critical thinking.

  11. Application of Molecular Adsorber Coatings in Chamber A for the James Webb Space Telescope

    Science.gov (United States)

    Abraham, Nithin S.

    2017-01-01

    As a coating made of highly porous zeolite materials, the Molecular Adsorber Coating (MAC) was developed to capture outgassed molecular contaminants, such as hydrocarbons and silicones. For spaceflight applications, the adsorptive capabilities of the coating can alleviate on-orbit outgassing concerns on or near sensitive surfaces and instruments within the spacecraft. Similarly, this sprayable paint technology has proven to be significantly beneficial for ground-based space applications, in particular, for vacuum chamber environments. This presentation describes the application of the MAC technology for the James Webb Space Telescope (JWST) at NASA Johnson Space Center (JSC). The coating was used as a mitigation tool to entrap outgassed contaminants, specifically silicone-based diffusion pump oil, from within JSCs cryogenic optical vacuum chamber test facility called Chamber A. This presentation summarizes the background, fabrication, installation, chemical analysis test results, and future plans for the MAC technology, which was effectively used to protect the JWST test equipment from vacuum chamber contamination. As a coating made of highly porous zeolite materials, the Molecular Adsorber Coating (MAC) was developed to capture outgassed molecular contaminants, such as hydrocarbons and silicones. For spaceflight applications, the adsorptive capabilities of the coating can alleviate on-orbit outgassing concerns on or near sensitive surfaces and instruments within the spacecraft. Similarly, this sprayable paint technology has proven to be significantly beneficial for ground-based space applications, in particular, for vacuum chamber environments. This presentation describes the application of the MAC technology for the James Webb Space Telescope (JWST) at NASA Johnson Space Center (JSC). The coating was used as a mitigation tool to entrap outgassed contaminants, specifically silicone-based diffusion pump oil, from within JSCs cryogenic optical vacuum chamber test

  12. Beïnvloeding van snelheidsgedrag door nudging : vragenlijstonderzoek naar het effect van Dick Bruna-borden op geschatte rijsnelheid binnen de bebouwde kom.

    NARCIS (Netherlands)

    Goldenbeld, C. Groot-Mesken, J. de & Rijsdijk, H.A.

    2016-01-01

    Influencing speed behaviour by nudging : questionnaire study into the effect of Dick Bruna1 traffic signs on the estimated driving speeds in urban areas. Speed is an important risk factor in traffic. Measurements within urban areas on 30- and 50 km/hour roads show that the percentage of speeders on

  13. Implications of Two Well-Known Models for Instructional Designers in Distance Education: Dick-Carey versus Morrison-Ross-Kemp

    Science.gov (United States)

    Akbulut, Yavuz

    2007-01-01

    This paper first summarizes, and then compares and contrasts two well-known instructional design models: Dick and Carey Model (DC) and Morrison, Ross and Kemp model (MRK). The target audiences of both models are basically instructional designers. Both models have applications for different instructional design settings. They both see the…

  14. Fano-Agarwal couplings and non-rotating wave approximation in single-photon timed Dicke subradiance

    Science.gov (United States)

    Mirza, Imran M.; Begzjav, Tuguldur

    2016-04-01

    Recently a new class of single-photon timed Dicke (TD) subradiant states has been introduced with possible applications in single-photon-based quantum information storage and on demand ultrafast retrieval (Scully M. O., Phys. Rev. Lett., 115 (2015) 243602). However, the influence of any kind of virtual processes on the decay of these new kind of subradiant states has been left as an open question. In the present paper, we focus on this problem in detail. In particular, we investigate how pure Fano-Agarwal couplings and other virtual processes arising from non-rotating wave approximation impact the decay of otherwise sub- and superradiant states. In addition to the overall virtual couplings among all TD states, we also focus on the dominant role played by the couplings between specific TD states.

  15. Eocene bituminous coal deposits of the Claiborne group, Webb County, Texas

    Science.gov (United States)

    Hook, Robert W.; Warwick, Peter D.; Warwick, Peter D.; Karlsen, Alexander K.; Merrill, Matthew D.; Valentine, Brett J.

    2011-01-01

    Two bituminous coal zones, the San Pedro and the Santo Tomas, in the middle Eocene Claiborne Group of Webb County, south Texas (Figure 1), are among the coal resources that are not evaluated quantitatively as part of the current Gulf Coastal Plain coal resource assessment. Coal beds within these zones were mined by underground methods northwest of Laredo until 1939 and have been intermittently mined at the surface since 1979. These coals have long been regarded as unique within the Gulf Coast Tertiary coal-bearing section because they are high-volatile C bituminous in rank and because their physical characteristics resemble upper Carboniferous cannel coals of the Appalachians and Europe.Discontinuous exposures of the Santo Tomas and the underlying San Pedro coal zone extend northwestward from Dolores for approximately 15 to 21 mi along the breaks of the Rio Grande and its tributaries in Webb County (Figure 1). This part of south Texas lies along the southwestern flank of the Rio Grande Embayment, which extends south and southeastwardly through the Mexican States of Coahuila, Nuevo León, and Tamaulipas (Figure 1). Within the embayment, the lower to middle part of the Claiborne Group consists of marine mudstones (Reklaw Formation) in the east and northeast and sandstones and mudstones (Bigford Formation) in the south and southwest (Figure 2). The marine mudstones coarsen upward into fluvial-deltaic sandstones (Queen City Sand) that prograded gulfward across eastern and central Texas (Guevara and Garcia, 1972). To the west and southwest, the interval overlying the Bigford Formation becomes less sandy, and claystones (El Pico Clay) predominate. Although the San Pedro coal zone has been placed traditionally near the top of the Bigford Formation and the Santo Tomas coal zone near the base of the El Pico Clay, recent work has failed to validate a mappable contact between these formations (Warwick and Hook, 1995). The coal beds dip northeast at less than 2 degrees towards

  16. Extra Solar Planetary Imaging Coronagraph and Science Requirements for the James Webb Telescope Observatory

    Science.gov (United States)

    Clampin, Mark

    2004-01-01

    1) Extra solar planetary imaging coronagraph. Direct detection and characterization of Jovian planets, and other gas giants, in orbit around nearby stars is a necessary precursor to Terrestrial Planet Finder 0 in order to estimate the probability of Terrestrial planets in our stellar neighborhood. Ground based indirect methods are biased towards large close in Jovian planets in solar systems unlikely io harbor Earthlike planets. Thus to estimate the relative abundances of terrestrial planets and to determine optimal observing strategies for TPF a pathfinder mission would be desired. The Extra-Solar Planetary Imaging Coronagraph (EPIC) is such a pathfinder mission. Upto 83 stellar systems are accessible with a 1.5 meter unobscured telescope and coronagraph combination located at the Earth-Sun L2 point. Incorporating radiometric and angular resolution considerations show that Jovians could be directly detected (5 sigma) in the 0.5 - 1.0 micron band outside of an inner working distance of 5/D with integration times of -10 - 100 hours per observation. The primary considerations for a planet imager are optical wavefront quality due to manufacturing, alignment, structural and thermal considerations. pointing stability and control, and manufacturability of coronagraphic masks and stops to increase the planetary-to- stellar contrast and mitigate against straylight. Previously proposed coronagraphic concepts are driven to extreme tolerances. however. we have developed and studied a mission, telescope and coronagraphic detection concept, which is achievable in the time frame of a Discovery class NASA mission. 2) Science requirements for the James Webb Space Telescope observatory. The James Webb Space Observatory (JWST) is an infrared observatory, which will be launched in 201 1 to an orbit at L2. JWST is a segmented, 18 mirror segment telescope with a diameter of 6.5 meters, and a clear aperture of 25 mA2. The telescope is designed to conduct imaging and spectroscopic

  17. Cryo Testing of tbe James Webb Space Telescope's Integrated Science Instrument Module

    Science.gov (United States)

    VanCampen, Julie

    2004-01-01

    The Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope will be integrated and tested at the Environmental Test Facilities at Goddard Space Flight Center (GSFC). The cryogenic thermal vacuum testing of the ISIM will be the most difficult and problematic portion of the GSFC Integration and Test flow. The test is to validate the coupled interface of the science instruments and the ISIM structure and to sufficiently stress that interface while validating image quality of the science instruments. The instruments and the structure are not made from the same materials and have different CTE. Test objectives and verification rationale are currently being evaluated in Phase B of the project plan. The test program will encounter engineering challenges and limitations, which are derived by cost and technology many of which can be mitigated by facility upgrades, creative GSE, and thorough forethought. The cryogenic testing of the ISIM will involve a number of risks such as the implementation of unique metrology techniques, mechanical, electrical and optical simulators housed within the cryogenic vacuum environment. These potential risks are investigated and possible solutions are proposed.

  18. The James Webb STEM Innovation Project: Bringing JWST to the Education Community

    Science.gov (United States)

    Eisenhamer, Bonnie; Harris, J.; Ryer, H.; Taylor, J.; Bishop, M.

    2012-01-01

    Building awareness of a NASA mission prior to launch and connecting that mission to the education community can be challenging. In order to address this challenge, the Space Telescope Science Institute's Office of Public Outreach has developed the James Webb STEM innovation Project (SIP) - an interdisciplinary project that focuses on the engineering aspects and potential scientific discoveries of JWST, while incorporating elements of project-based learning. Students in participating schools will use skills from multiple subject areas to research an aspect of the JWST's design or potential science and create models, illustrated essays, or technology-based projects to demonstrate their learning. Student projects will be showcased during special events at select venues in the project states - thus allowing parents and community members to also be benefactors of the project. Currently, the SIP is being piloted in New York, California, and Maryland. In addition, we will be implementing the SIP in partnership with NASA Explorer Schools in the states of New Mexico, Michigan, Texas, Tennessee, and Iowa.

  19. New Frontiers for Massive Star Winds: Imaging and Spectroscopy with the James Webb Space Telescope

    Science.gov (United States)

    Sonneborn, George

    2007-01-01

    The James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope scheduled for launch in 2013. JWST will find the first stars and galaxies that formed in the early universe, connecting the Big Bang to our own Milky Way galaxy. JWST will peer through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own Solar System. JWST's instruments are designed to work primarily in the infrared range of 1 - 28 microns, with some capability in the visible range. JWST will have a large mirror, 6.5 meters in diameter, and will be diffraction-limited at 2 microns (0.1 arcsec resolution). JWST will be placed in an L2 orbit about 1.5 million km from the Earth. The instruments will provide imaging, coronography, and multi-object and integral-field spectroscopy across the full 1 - 28 micron wavelength range. The breakthrough capabilities of JWST will enable new studies of massive star winds from the Milky Way to the early universe.

  20. James Webb Space Telescope Optical Simulation Testbed: Segmented Mirror Phase Retrieval Testing

    Science.gov (United States)

    Laginja, Iva; Egron, Sylvain; Brady, Greg; Soummer, Remi; Lajoie, Charles-Philippe; Bonnefois, Aurélie; Long, Joseph; Michau, Vincent; Choquet, Elodie; Ferrari, Marc; Leboulleux, Lucie; Mazoyer, Johan; N’Diaye, Mamadou; Perrin, Marshall; Petrone, Peter; Pueyo, Laurent; Sivaramakrishnan, Anand

    2018-01-01

    The James Webb Space Telescope (JWST) Optical Simulation Testbed (JOST) is a hardware simulator designed to produce JWST-like images. A model of the JWST three mirror anastigmat is realized with three lenses in form of a Cooke Triplet, which provides JWST-like optical quality over a field equivalent to a NIRCam module, and an Iris AO segmented mirror with hexagonal elements is standing in for the JWST segmented primary. This setup successfully produces images extremely similar to NIRCam images from cryotesting in terms of the PSF morphology and sampling relative to the diffraction limit.The testbed is used for staff training of the wavefront sensing and control (WFS&C) team and for independent analysis of WFS&C scenarios of the JWST. Algorithms like geometric phase retrieval (GPR) that may be used in flight and potential upgrades to JWST WFS&C will be explored. We report on the current status of the testbed after alignment, implementation of the segmented mirror, and testing of phase retrieval techniques.This optical bench complements other work at the Makidon laboratory at the Space Telescope Science Institute, including the investigation of coronagraphy for segmented aperture telescopes. Beyond JWST we intend to use JOST for WFS&C studies for future large segmented space telescopes such as LUVOIR.

  1. Challenges with Electrical, Electronics, and Electromechanical Parts for James Webb Space Telescope

    Science.gov (United States)

    Jah, Muzar A.; Jeffers, Basil S.

    2016-01-01

    James Webb Space Telescope (JWST) is the space-based observatory that will extend the knowledge gained by the Hubble Space Telescope (HST). Hubble focuses on optical and ultraviolet wavelengths while JWST focuses on the infrared portion of the electromagnetic spectrum, to see the earliest stars and galaxies that formed in the Universe and to look deep into nearby dust clouds to study the formation of stars and planets. JWST, which commenced creation in 1996, is scheduled to launch in 2018. It includes a suite of four instruments, the spacecraft bus, optical telescope element, Integrated Science Instrument Module (ISIM, the platform to hold the instruments), and a sunshield. The mass of JWST is approximately 6200 kg, including observatory, on-orbit consumables and launch vehicle adaptor. Many challenges were overcome while providing the electrical and electronic components for the Goddard Space Flight Center hardware builds. Other difficulties encountered included developing components to work at cryogenic temperatures, failures of electronic components during development and flight builds, Integration and Test electronic parts problems, and managing technical issues with international partners. This paper will present the context of JWST from a EEE (electrical, electronic, and electromechanical) perspective with examples of challenges and lessons learned throughout the design, development, and fabrication of JWST in cooperation with our associated partners including the Canadian Space Agency (CSA), the European Space Agency (ESA), Lockheed Martin and their respective associated partners. Technical challenges and lessons learned will be discussed.

  2. Model-based thermal system design optimization for the James Webb Space Telescope

    Science.gov (United States)

    Cataldo, Giuseppe; Niedner, Malcolm B.; Fixsen, Dale J.; Moseley, Samuel H.

    2017-10-01

    Spacecraft thermal model validation is normally performed by comparing model predictions with thermal test data and reducing their discrepancies to meet the mission requirements. Based on thermal engineering expertise, the model input parameters are adjusted to tune the model output response to the test data. The end result is not guaranteed to be the best solution in terms of reduced discrepancy and the process requires months to complete. A model-based methodology was developed to perform the validation process in a fully automated fashion and provide mathematical bases to the search for the optimal parameter set that minimizes the discrepancies between model and data. The methodology was successfully applied to several thermal subsystems of the James Webb Space Telescope (JWST). Global or quasiglobal optimal solutions were found and the total execution time of the model validation process was reduced to about two weeks. The model sensitivities to the parameters, which are required to solve the optimization problem, can be calculated automatically before the test begins and provide a library for sensitivity studies. This methodology represents a crucial commodity when testing complex, large-scale systems under time and budget constraints. Here, results for the JWST Core thermal system will be presented in detail.

  3. Ambient Optomechanical Alignment and Pupil Metrology for the Flight Instruments Aboard the James Webb Space Telescope

    Science.gov (United States)

    Coulter, Phillip; Beaton, Alexander; Gum, Jeffrey S.; Hadjimichael, Theodore J.; Hayden, Joseph E.; Hummel, Susann; Hylan, Jason E.; Lee, David; Madison, Timothy J.; Maszkiewicz, Michael; hide

    2014-01-01

    The James Webb Space Telescope science instruments are in the final stages of being integrated into the Integrated Science Instrument Module (ISIM) element. Each instrument is tied into a common coordinate system through mechanical references that are used for optical alignment and metrology within ISIM after element-level assembly. In addition, a set of ground support equipment (GSE) consisting of large, precisely calibrated, ambient, and cryogenic structures are used as alignment references and gauges during various phases of integration and test (I&T). This GSE, the flight instruments, and ISIM structure feature different types of complimentary metrology targeting. These GSE targets are used to establish and track six degrees of freedom instrument alignment during I&T in the vehicle coordinate system (VCS). This paper describes the optomechanical metrology conducted during science instrument integration and alignment in the Spacecraft Systems Development and Integration Facility (SSDIF) cleanroom at NASA Goddard Space Flight Center (GSFC). The measurement of each instrument's ambient entrance pupil location in the telescope coordinate system is discussed. The construction of the database of target locations and the development of metrology uncertainties is also discussed.

  4. Almond (Prunus dulcis (Mill.) D.A. Webb) skins as a potential source of bioactive polyphenols.

    Science.gov (United States)

    Monagas, Maria; Garrido, Ignacio; Lebrón-Aguilar, Rosa; Bartolome, Begoña; Gómez-Cordovés, Carmen

    2007-10-17

    An exhaustive study of the phenolic composition of almond ( Prunus dulcis (Mill.) D.A. Webb) skins was carried out in order to evaluate their potential application as a functional food ingredient. Using the HPLC-DAD/ESI-MS technique, a total of 33 compounds corresponding to flavanols, flavonols, dihydroflavonols and flavanones, and other nonflavonoid compounds were identified. Peaks corresponding to another 23 structure-related compounds were also detected. MALDI-TOF MS was applied to characterize almond skin proanthocyanidins, revealing the existence of a series of A- and B-type procyanidins and propelargonidins up to heptamers, and A- and B-type prodelphinidins up to hexamers. Flavanols and flavonol glycosides were the most abundant phenolic compounds in almond skins, representing up to 38-57% and 14-35% of the total quantified phenolics, respectively. Due to their antioxidant properties, measured as oxygen-radical absorbance capacity (ORAC) at 0.398-0.500 mmol Trolox/g, almond skins can be considered as a value-added byproduct for elaborating dietary antioxidant ingredients.

  5. Studying Galaxy Formation with the Hubble, Spitzer and James Webb Space Telescopes

    Science.gov (United States)

    Gardner, Jonathan P.

    2009-01-01

    The deepest optical to infrared observations of the universe include the Hubble Deep Fields, the Great Observatories Origins Deep Survey and the recent Hubble Ultra-Deep Field. Galaxies are seen in these surveys at redshifts z greater than 6, less than 1 Gyr after the Big Bang, at the end of a period when light from the galaxies has reionized Hydrogen in the inter-galactic medium. These observations, combined with theoretical understanding, indicate that the first stars and galaxies formed at z greater than 10, beyond the reach of the Hubble and Spitzer Space Telescopes. To observe the first galaxies, NASA is planning the James Webb Space Telescope (JWST), a large (6.5m), cold (less than 50K), infrared-optimized observatory to be launched early in the next decade into orbit around the second Earth-Sun Lagrange point. JWST will have four instruments: The Near-Infrared Camera, the Near-Infrared multi-object Spectrograph, and the Tunable Filter Imager will cover the wavelength range 0.6 to 5 microns, while the Mid-Infrared Instrument will do both imaging and spectroscopy from 5 to 28.5 microns. In addition to JWST's ability to study the formation and evolution of galaxies, I will also briefly review its expected contributions to studies of the formation of stars and planetary systems, and discuss recent progress in constructing the observatory.

  6. From the Big Bang to the Nobel Prize and on to the James Webb Space Telescope

    Science.gov (United States)

    Mather, John C.

    2008-01-01

    The history of the universe in a nutshell, from the Big Bang to now. and on to the future - John Mather will tell the story of how we got here, how the Universe began with a Big Bang, how it could have produced an Earth where sentient beings can live, and how those beings are discovering their history. Mather was Project Scientist for NASA's Cosmic Background Explorer (COBE) satellite, which measured the spectrum (the color) of the heat radiation from the Big Bang, discovered hot and cold spots in that radiation, and hunted for the first objects that formed after the great explosion. He will explain Einstein's biggest mistake, show how Edwin Hubble discovered the expansion of the univerre, how the COBE mission was built, and how the COBE data support the Big Bang theory. He will also show NASA's plans for the next great telescope in space, the Jarnes Webb Space Telescope. It will look even farther back in time than the Hubble Space Telescope, and will look inside the dusty cocoons where rtars and planets are being born today. Planned for launch in 2013, it may lead to another Nobel Prize for some lucky observer.

  7. From the Big Bang to the Nobel Prize and on to James Webb Space Telescope

    Science.gov (United States)

    Mather, John C.

    2009-01-01

    The history of the universe in a nutshell, from the Big Bang to now, and on to the future - John Mather will tell the story of how we got here, how the Universe began with a Big Bang, how it could have produced an Earth where sentient beings can live, and how those beings are discovering their history. Mather was Project Scientist for NASA s Cosmic Background Explorer (COBE) satellite, which measured the spectrum (the color) of the heat radiation from the Big Bang, discovered hot and cold spots in that radiation, and hunted for the first objects that formed after the great explosion. He will explain Einstein s biggest mistake, show how Edwin Hubble discovered the expansion of the universe, how the COBE mission was built, and how the COBE data support the Big Bang theory. He will also show NASA s plans for the next great telescope in space, the James Webb Space Telescope. It will look even farther back in time than the Hubble Space Telescope, and will look inside the dusty cocoons where stars and planets are being born today. Planned for launch in 2013, it may lead to another Nobel Prize for some lucky observer.

  8. Analgesic and Antioxidant Activities of Algerian Retama raetam (Forssk. Webb & Berthel Extracts

    Directory of Open Access Journals (Sweden)

    Samah Djeddi

    2013-05-01

    Full Text Available Part of this work deals with t he isolation and structure elucidation of the main polar secondary metabolites of the aerial parts of Retama raetam (Forssk. Webb & Berthel, as well as the evaluation of their potential analgesic properties , while the rest deals with the antioxidant activities of the aqueous extracts of roots, stem, fruits and flowers of the plant . It was found that the isoflavones g enistein 1, 6-hydroxygenistein 2, 3'-O-methylorobol 3, pratensein 4, biochanin A 8, the flavones 6-hydroxyapigenin 7 and luteolin 5, the flavonol kaempferol 6,as well as the phenolic compound p-coumaric acid 9 reduce significantly the pain at a concentration dose of 1 mg/kg. The most active compounds were 3 and 8 (86.19% and 75.23%, respectively. The obtained aqueous extracts of R. raetam were also evaluated for their antioxidant activities using two different photometric methods; the results revealed that all extracts exerted very low free radical scavenging activity compared to the well-known butylated hydroxytoluene (BHT and lower hydrogen peroxide blocking activity than positive control gallic acid.

  9. Statistical analysis of the surface figure of the James Webb Space Telescope

    Science.gov (United States)

    Lightsey, Paul A.; Chaney, David; Gallagher, Benjamin B.; Brown, Bob J.; Smith, Koby; Schwenker, John

    2012-09-01

    The performance of an optical system is best characterized by either the point spread function (PSF) or the optical transfer function (OTF). However, for system budgeting purposes, it is convenient to use a single scalar metric, or a combination of a few scalar metrics to track performance. For the James Webb Space Telescope, the Observatory level requirements were expressed in metrics of Strehl Ratio, and Encircled Energy. These in turn were converted to the metrics of total rms WFE and rms WFE within spatial frequency domains. The 18 individual mirror segments for the primary mirror segment assemblies (PMSA), the secondary mirror (SM), tertiary mirror (TM), and Fine Steering Mirror have all been fabricated. They are polished beryllium mirrors with a protected gold reflective coating. The statistical analysis of the resulting Surface Figure Error of these mirrors has been analyzed. The average spatial frequency distribution and the mirror-to-mirror consistency of the spatial frequency distribution are reported. The results provide insight to system budgeting processes for similar optical systems.

  10. Evaluation of the chemical and nutritional characteristics of almonds (Prunus dulcis (Mill). D.A. Webb) as influenced by harvest time and cultivar.

    Science.gov (United States)

    Summo, Carmine; Palasciano, Marino; De Angelis, Davide; Paradiso, Vito M; Caponio, Francesco; Pasqualone, Antonella

    2018-04-30

    Several authors studied the effect of harvest time on chemical and nutritional composition of almonds, but the results are partly conflicting, probably due to differences in the cultivars considered and to different agronomic and climatic conditions in the growing areas. In this paper the influence of harvest time and cultivar on the chemical and nutritional composition of almonds (Prunus dulcis (Mill). D.A. Webb) was evaluated. Ten cultivars were considered, grown in the same orchard and subjected to the same agronomical regime. Almonds were collected at two different harvest times: i) when the fruits were unripe, but already edible, and showed green and moist hull, and ii) when the fruits were ripe, with dry brown hull. The analyses of proximate composition, fatty acid profile, total phenolic compounds and antioxidant activity were carried out. Lipid content increased (palmonds. Genotype strongly influenced fatty acid composition and total phenolic compounds. The changes of bioactive compounds and antioxidant activity suggest that the synthesis of antioxidants occur also in the last stage of ripening. Unripe almonds, a valuable niche product, showed interesting nutritional value. This article is protected by copyright. All rights reserved.

  11. Intermediate accelerated solutions as generic late-time attractors in a modified Jordan-Brans-Dicke theory

    Energy Technology Data Exchange (ETDEWEB)

    Cid, Antonella [Grupo de Cosmología y Gravitación GCG-UBB and Departamento de Física, Universidad del Bío-Bío, Casilla 5-C, Concepción (Chile); Leon, Genly [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla 4950, Valparaíso (Chile); Leyva, Yoelsy, E-mail: acidm@ubiobio.cl, E-mail: genly.leon@ucv.cl, E-mail: yoelsy.leyva@uta.cl [Departamento de Física, Facultad de Ciencias, Universidad de Tarapacá, Casilla 7-D, Arica (Chile)

    2016-02-01

    In this paper we investigate the evolution of a Jordan-Brans-Dicke scalar field, Φ, with a power-law potential in the presence of a second scalar field, φ, with an exponential potential, in both the Jordan and the Einstein frames. We present the relation of our model with the induced gravity model with power-law potential and the integrability of this kind of models is discussed when the quintessence field φ is massless, and has a small velocity. The fact that for some fine-tuned values of the parameters we may get some integrable cosmological models, makes our choice of potentials very interesting. We prove that in Jordan-Brans-Dicke theory, the de Sitter solution is not a natural attractor. Instead, we show that the attractor in the Jordan frame corresponds to an ''intermediate accelerated'' solution of the form a(t) ≅ e{sup α{sub 1} t{sup p{sup {sub 1}}}}, as t → ∞ where α{sub 1} > 0 and 0 < p{sub 1} < 1, for a wide range of parameters. Furthermore, when we work in the Einstein frame we get that the attractor is also an ''intermediate accelerated'' solution of the form a(t) ≅ e{sup α{sub 2} tp{sub 2}} as t → ∞ where α{sub 2} > 0 and 0

  12. Intermediate accelerated solutions as generic late-time attractors in a modified Jordan-Brans-Dicke theory

    International Nuclear Information System (INIS)

    Cid, Antonella; Leon, Genly; Leyva, Yoelsy

    2016-01-01

    In this paper we investigate the evolution of a Jordan-Brans-Dicke scalar field, Φ, with a power-law potential in the presence of a second scalar field, φ, with an exponential potential, in both the Jordan and the Einstein frames. We present the relation of our model with the induced gravity model with power-law potential and the integrability of this kind of models is discussed when the quintessence field φ is massless, and has a small velocity. The fact that for some fine-tuned values of the parameters we may get some integrable cosmological models, makes our choice of potentials very interesting. We prove that in Jordan-Brans-Dicke theory, the de Sitter solution is not a natural attractor. Instead, we show that the attractor in the Jordan frame corresponds to an ''intermediate accelerated'' solution of the form a(t) ≅ e α 1  t p 1 , as t → ∞ where α 1  > 0 and 0 < p 1  < 1, for a wide range of parameters. Furthermore, when we work in the Einstein frame we get that the attractor is also an ''intermediate accelerated'' solution of the form a(t) ≅ e α 2  tp 2 as t → ∞ where α 2  > 0 and 0

  13. En camino hacia el Moby Dick de Herman Melville, encontré… Algunas notas preliminares de un libro sin escribir On My Way to Herman Melville’s Moby Dick, I Found … Some Preliminary Remarks from an Unwritten Book

    Directory of Open Access Journals (Sweden)

    Burkard Sievers

    2009-06-01

    Full Text Available Propósito: El autor está revisitando el cuerpo de sus manuscritos sobre el Moby Dick de Herman Melville, que comenzó a escribir hace unos 15 años. Aunque estos escritos siguen constituyendo un “libro sin escribir”, las obras de Melville tuvieron un impacto duradero sobre su pensamiento - abrieron nuevo caminos de inspiración- y escritura hasta el presente. El objetivo del documento es revelar algunas experiencias, estímulos, dificultades y emociones concomitantes con la escritura académica que siguen estando en su mayoría, escondidas del lector. Diseño/ metodología/acercamiento: Este artículo es una reminiscencia personal sobre la experiencia de la escritura académica de unas cuatro décadas. Es una historia de cómo un académico se familiariza con, y luego es influenciado/inspirado por una obra literaria, y descubre cuántos tópicos organizacionales pueden ser iluminados por trabajos literarios. Descubrimientos: Ni siquiera un libro sin escribir lleva necesariamente a descuidar completamente lo que había sido escrito. Esto podría ser un alivio y un estímulo para otros, quienes se dan cuenta de que no están solos en este sentido. Originalidad/valor: el artículo aporta un poco más de entendimiento sobre la experiencia no-tan-obvia y generalmente escondida, del “proceso de producción” de la escritura académica, e ilustra la relevancia e importancia de la literatura para pensar más allá, tópicos tales como la Administración y la organización.Purpose: The author is revisiting the body of his manuscripts on Herman Melville’s Moby Dick, which he began writing some 15 years ago. Though these writings have remained an ‘unwritten book’, Melville’s works had a lasting impact on his thinking and writing up to the present. He reveals some of the experiences and emotions concomitant with academic writing that remain more often than not hidden from the reader. Design/methodology/approach: This paper is a personal

  14. Effects of Retama raetam (Forssk. Webb & Berthel. (Fabaceae on the central nervous system in experimental animals

    Directory of Open Access Journals (Sweden)

    Al-Tubuly Rida A.

    2011-01-01

    Full Text Available Retama raetam (Forssk. Webb & Berthel. (Fabaceae, commonly known as ‘raetam’ or ‘broom bush’, is a desert shrub that grows abundantly in North-African countries, Palestine and Syria. Traditionally, this plant has been used as an abortifacient, a purgative and a vermifuge. In the present study, the effect of the methanol (MeOH extract of the aerial parts of R. raetam on the central nervous system (CNS has been evaluated using a mice model. In the photoelectrical cell test, the extract of R. raetam (ERR at a dose of 125 mg/kg body weight did not exhibit any effect on the spontaneous motor activity in mice. At a dose of 250 mg/kg body weight, ERR increased ambulatory movement, but had no effect on the non-ambulatory movement, while a dose of 375 mg/kg body weight decreased both ambulatory and non-ambulatory movements. The effect of ERR on the anxiety levels and behaviors of mice was investigated using the elevated plus-maze test. At doses of 125, 250 and 375 mg/kg body weight, ERR decreased anxiety levels without showing an effect on the total activity; it did not affect anxiety levels but increased the total activity; it increased anxiety levels and decreased the total activity, respectively. In the diazepam-induced sleep test, ERR increased the onset of sleep without affecting the duration of sleep at the dose of 250 mg/kg body weight. The dose of 375 mg/kg body weight decreased the onset of sleep while increasing the duration of sleep. ERR did not exhibit any effect on the diazepam-induced sleep in the presence of flumazenil or picrotoxin.

  15. Prospects for Habitable World Detections Using James Webb Space Telescope (JWST)

    Science.gov (United States)

    Deming, Drake

    2010-01-01

    Doppler and transit surveys are finding extrasolar planets of ever smaller mass and radius, and are now sampling the domain of superEarths. Recent results from the Doppler surveys suggest that discovery of a transiting superEarth in the habitable zone of a lower main sequence star may be possible. We evaluate the prospects for an all-sky transit survey targeted to the brightest stars I that would find the most favorable cases for photometric and spectroscopic characterization using the James Webb Space Telescope. We use the proposed Transiting Exoplanet Survey Satellite (TESS) as representative of an all-sky survey. We couple the simulated TESS yield to a sensitivity model for the MIRI and NIRSpec instruments on JWST. Our sensitivity model includes all currently known and anticipated sources of random and systematic error for these instruments. We focus on the TESS planets with radii between Earth and Neptune. Our simulations consider secondary eclipse filter photometry using JWST/MIRI, comparing the 11- and 15- micron bands to measure carbon dioxide absorption in superEarths, as well as JWST!NIRSpec spectroscopy of water absorption from 1.7-3.0 microns, and carbon dioxide absorption at 4.3 microns. We find that JWST will be capable of characterizing dozens of TESS superEarths with temperatures above the habitable range, using both MIRI and NIRspec. We project that TESS will discover about eight nearby habitable transiting superEarths, all orbiting lower main sequence stars. The principal sources of uncertainty in the prospects for JWST characterization of habitable superEarths are superEarth frequency and the nature of superEarth atmospheres. Based on our estimates of these uncertainties, we project that JWST will be able to measure the temperature, and identify molecular absorptions (water, carbon dioxide) in one to four nearby habitable TESS superEarths orbiting lower main sequence stars.

  16. DETECTABILITY OF FREE FLOATING PLANETS IN OPEN CLUSTERS WITH THE JAMES WEBB SPACE TELESCOPE

    International Nuclear Information System (INIS)

    Pacucci, Fabio; Ferrara, Andrea; D'Onghia, Elena

    2013-01-01

    Recent observations have shown the presence of extra-solar planets in Galactic open stellar clusters, such as in Praesepe (M44). These systems provide a favorable environment for planetary formation due to the high heavy-element content exhibited by the majority of their population. The large stellar density, and corresponding high close-encounter event rate, may induce strong perturbations of planetary orbits with large semimajor axes. Here we present a set of N-body simulations implementing a novel scheme to treat the tidal effects of external stellar perturbers on planetary orbit eccentricity and inclination. By simulating five nearby open clusters, we determine the rate of occurrence of bodies extracted from their parent stellar system by quasi-impulsive tidal interactions. We find that the specific free-floating planet production rate N-dot o (total number of free-floating planets per unit of time, normalized by the total number of stars), is proportional to the stellar density ρ * of the cluster: N-dot o =αρ ⋆ , with α = (23 ± 5) × 10 –6 pc 3 Myr –1 . For the Pleiades (M45), we predict that ∼26% of stars should have lost their planets. This raises the exciting possibility of directly observing these wandering planets with the James Webb Space Telescope in the near-infrared band. Assuming a surface temperature for the planet of ∼500 K, a free-floating planet of Jupiter size inside the Pleiades would have a specific flux of F ν (4.4 μm) ≈4 × 10 2  nJy, which would lead to a very clear detection (S/N ∼ 100) in only one hour of integration

  17. Unique Spectroscopy and Imaging of Mars with the James Webb Space Telescope

    Science.gov (United States)

    Villanueva, Geronimo L.; Altieri, Francesca; Clancy, R. Todd; Encrenaz, Therese; Fouchet, Thierry; Hartogh, Paul; Lellouch, Emmanuel; Lopez-Valverde, Miguel A.; Mumma, Michael J.; Novak, Robert E.; hide

    2016-01-01

    In this paper, we summarize the main capabilities of the James Webb Space Telescope (JWST) for performing observations of Mars. The distinctive vantage point of JWST at the Sun-Earth Lagrange point (L2) will allow sampling the full observable disk, permitting the study of short-term phenomena, diurnal processes (across the east-west axis), and latitudinal processes between the hemispheres (including seasonal effects) with excellent spatial resolutions (0.''07 at 2 micron). Spectroscopic observations will be achievable in the 0.7-5 micron spectral region with NIRSpec at a maximum resolving power of 2700 and with 8000 in the 1-1.25 micron range. Imaging will be attainable with the Near-Infrared Camera at 4.3 micrometers and with two narrow filters near 2 micron, while the nightside will be accessible with several filters in 0.5 to 2 micron. Such a powerful suite of instruments will be a major asset for the exploration and characterization of Mars. Some science cases include the mapping of the water D/H ratio, investigations of the Martian mesosphere via the characterization of the non-local thermodynamic equilibrium CO2 emission at 4.3 micron, studies of chemical transport via observations of the O2 nightglow at 1.27 micron, high-cadence mapping of the variability dust and water-ice clouds, and sensitive searches for trace species and hydrated features on the Martian surface. In-flight characterization of the instruments may allow for additional science opportunities.

  18. Detectability of Free Floating Planets in Open Clusters with the James Webb Space Telescope

    Science.gov (United States)

    Pacucci, Fabio; Ferrara, Andrea; D'Onghia, Elena

    2013-12-01

    Recent observations have shown the presence of extra-solar planets in Galactic open stellar clusters, such as in Praesepe (M44). These systems provide a favorable environment for planetary formation due to the high heavy-element content exhibited by the majority of their population. The large stellar density, and corresponding high close-encounter event rate, may induce strong perturbations of planetary orbits with large semimajor axes. Here we present a set of N-body simulations implementing a novel scheme to treat the tidal effects of external stellar perturbers on planetary orbit eccentricity and inclination. By simulating five nearby open clusters, we determine the rate of occurrence of bodies extracted from their parent stellar system by quasi-impulsive tidal interactions. We find that the specific free-floating planet production rate \\dot{N}_o (total number of free-floating planets per unit of time, normalized by the total number of stars), is proportional to the stellar density ρsstarf of the cluster: \\dot{N}_o = \\alpha \\rho _\\star, with α = (23 ± 5) × 10-6 pc3 Myr-1. For the Pleiades (M45), we predict that ~26% of stars should have lost their planets. This raises the exciting possibility of directly observing these wandering planets with the James Webb Space Telescope in the near-infrared band. Assuming a surface temperature for the planet of ~500 K, a free-floating planet of Jupiter size inside the Pleiades would have a specific flux of F ν (4.4 μm) ≈4 × 102 nJy, which would lead to a very clear detection (S/N ~ 100) in only one hour of integration.

  19. DETECTABILITY OF FREE FLOATING PLANETS IN OPEN CLUSTERS WITH THE JAMES WEBB SPACE TELESCOPE

    Energy Technology Data Exchange (ETDEWEB)

    Pacucci, Fabio; Ferrara, Andrea [Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa (Italy); D' Onghia, Elena [University of Wisconsin, 475 Charter St., Madison, WI 53706 (United States)

    2013-12-01

    Recent observations have shown the presence of extra-solar planets in Galactic open stellar clusters, such as in Praesepe (M44). These systems provide a favorable environment for planetary formation due to the high heavy-element content exhibited by the majority of their population. The large stellar density, and corresponding high close-encounter event rate, may induce strong perturbations of planetary orbits with large semimajor axes. Here we present a set of N-body simulations implementing a novel scheme to treat the tidal effects of external stellar perturbers on planetary orbit eccentricity and inclination. By simulating five nearby open clusters, we determine the rate of occurrence of bodies extracted from their parent stellar system by quasi-impulsive tidal interactions. We find that the specific free-floating planet production rate N-dot {sub o} (total number of free-floating planets per unit of time, normalized by the total number of stars), is proportional to the stellar density ρ{sub *} of the cluster: N-dot {sub o}=αρ{sub ⋆}, with α = (23 ± 5) × 10{sup –6} pc{sup 3} Myr{sup –1}. For the Pleiades (M45), we predict that ∼26% of stars should have lost their planets. This raises the exciting possibility of directly observing these wandering planets with the James Webb Space Telescope in the near-infrared band. Assuming a surface temperature for the planet of ∼500 K, a free-floating planet of Jupiter size inside the Pleiades would have a specific flux of F {sub ν} (4.4 μm) ≈4 × 10{sup 2} nJy, which would lead to a very clear detection (S/N ∼ 100) in only one hour of integration.

  20. Author Details

    African Journals Online (AJOL)

    PROMOTING ACCESS TO AFRICAN RESEARCH. AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING AJOL · RESOURCES. Author Details. Journal Home > Advanced Search > Author Details. Log in or Register to get access to full text downloads.

  1. Author Correction

    DEFF Research Database (Denmark)

    Gröbner, Susanne N; Worst, Barbara C; Weischenfeldt, Joachim

    2018-01-01

    In this Article, author Benedikt Brors was erroneously associated with affiliation number '8' (Department of Developmental Neurobiology, St Jude Children's Research Hospital, Memphis, Tennessee, USA); the author's two other affiliations (affiliations '3' and '7', both at the German Cancer Researc...

  2. Author Details

    African Journals Online (AJOL)

    Author Details. Journal Home > Advanced Search > Author Details. Log in or Register to get access to full text downloads. ... An algorithm to retrieve Land Surface Temperature using Landsat-8 Dataset Abstract PDF. ISSN: 2225-8531.

  3. On the use of the Webb-Pearman-Leuning theory for closed-path eddy correlation measurements

    DEFF Research Database (Denmark)

    Ibrom, Andreas; Dellwik, Ebba; Larsen, Søren Ejling

    2007-01-01

    We consider an imperfection of real closed-path eddy correlation systems-the decoupling of the water vapour and CO2 concentrations-with respect to the application of the Webb-Pearman-Leuning (WPL) theory. It is described why and how the current application of the WPL theory needs to be adapted...... into account, over-corrected the annual flux by 21%, or 31 g m(-2) yr(-1), to which the decoupling effect contributed with 7%. We suggest either converting the raw data point-by-point to mixing ratios or using the uncorrected covariances of water vapour mole fractions with the vertical wind velocity that were...

  4. Comparison of Benedict-Webb-Rubin, Starling and Lee-Kesler equations of state for use in P-V-T calculations

    International Nuclear Information System (INIS)

    McFee, D.G.; Mueller, K.H.; Lielmezs, J.

    1982-01-01

    By means of the available experimental gas compressibility data, the predictive accuracy of the Benedict-Webb-Rubin, Starling and Lee-Kesler equations was tested over wide temperature and pressure ranges for the following commonly used industrial gases: CH 4 , C 2 H 6 , C 3 H 8 , CO 2 , Ar, He, H 2 and N 2 . The root mean square (RMS) percent errors calculated over the T-P range investigated for all compounds, showed a degree of superiority and ease of use of the Lee-Kesler equation over the Benedict-Webb-Rubin and Starling equations. In order to treat quantal fluids H 2 and He, the Benedict-Webb-Rubin equation was modified by making constant B 0 temperature dependent, while the Starling and Lee-Kesler equations were rewritten through inclusion of quantum effect corrected pseudo-critical state parameters. (orig.)

  5. Author's capabilities in author indexing

    International Nuclear Information System (INIS)

    Ooi, Shoichi

    1988-01-01

    The purpose of this paper is to provide a author capability of current author indexing practices in journal literature indexing practices in 'Journal of Nuclear Science and Technology of Japan'. This Journal employed keywords freely assigned by author and not taken from INIS Thesaurus or other vocabulary list. Author examined 413 literatures, comparing keywords assigned by the literatures' authors with descriptor's (ATOMINDEX) assigned by an experienced professional indexer. The results of the comparisons showed that the average set of terms assigned by author included about 70% of all the terms assigned to the same literature by the professional indexer. Authors eventually would contribute, for the most effective point to create reference to information is at the time of its generation. Consequently, it may be possible to transfer them easily to descriptors in every secondary information system. (author)

  6. Active galactic nucleus and quasar science with aperture masking interferometry on the James Webb Space Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Ford, K. E. Saavik; McKernan, Barry [Department of Science, Borough of Manhattan Community College, City University of New York, New York, NY 10007 (United States); Sivaramakrishnan, Anand; Martel, André R.; Koekemoer, Anton [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Lafrenière, David [Département de Physique, Université de Montréal, C.P. 6128 Succ. Centre-ville, QC H3C 3J7 (Canada); Parmentier, Sébastien [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States)

    2014-03-10

    Due to feedback from accretion onto supermassive black holes (SMBHs), active galactic nuclei (AGNs) are believed to play a key role in ΛCDM cosmology and galaxy formation. However, AGNs extreme luminosities and the small angular size of their accretion flows create a challenging imaging problem. We show that the James Webb Space Telescope's Near Infrared Imager and Slitless Spectrograph (JWST-NIRISS) Aperture Masking Interferometry (AMI) mode will enable true imaging (i.e., without any requirement of prior assumptions on source geometry) at ∼65 mas angular resolution at the centers of AGNs. This is advantageous for studying complex extended accretion flows around SMBHs and in other areas of angular-resolution-limited astrophysics. By simulating data sequences incorporating expected sources of noise, we demonstrate that JWST-NIRISS AMI mode can map extended structure at a pixel-to-pixel contrast of ∼10{sup –2} around an L = 7.5 point source, using short exposure times (minutes). Such images will test models of AGN feedback, fueling, and structure (complementary with ALMA observations), and are not currently supported by any ground-based IR interferometer or telescope. Binary point source contrast with NIRISS is ∼10{sup –4} (for observing binary nuclei in merging galaxies), significantly better than current ground-based optical or IR interferometry. JWST-NIRISS's seven-hole non-redundant mask has a throughput of 15%, and utilizes NIRISS's F277W (2.77 μm), F380M (3.8 μm), F430M (4.3 μm), and F480M (4.8 μm) filters. NIRISS's square pixels are 65 mas per side, with a field of view ∼2' × 2'. We also extrapolate our results to AGN science enabled by non-redundant masking on future 2.4 m and 16 m space telescopes working at long-UV to near-IR wavelengths.

  7. Creating the Thermal Environment for Safely Testing the James Webb Space Telescope at the Johnson Space Center's Chamber A

    Science.gov (United States)

    Homan, Jonathan L.; Lauterbach, John; Garcia, Sam

    2016-01-01

    Chamber A is the largest thermal vacuum chamber at the Johnson Space Center and is one of the largest space environment chambers in the world. The chamber is 19.8 m (65 ft) in diameter and 36.6 m (120 ft) tall and is equipped with cryogenic liquid nitrogen panels (shrouds) and gaseous helium shrouds to create a simulated space environment. The chamber was originally built to support testing of the Apollo Service and Command Module for lunar missions, but underwent major modifications to be able to test the James Webb Space Telescope in a simulated deep space environment. To date seven tests have been performed in preparation of testing the flight optics for the James Webb Space Telescope (JWST). Each test has had a uniquie thermal profile and set of thermal requirements for cooling down and warming up, controlling contamination, and releasing condensed air. These range from temperatures from 335K to 15K, with tight uniformity and controllability for maintining thermal stability and pressure control. One unique requirement for two test was structurally proof loading hardware by creating thermal gradients at specific temperatures. This paper will discuss the thermal requirements and goals of the tests, the original requirements of the chamber thermal systems for planned operation, and how the new requirements were met by the team using the hardware, system flexiblilty, and engineering creativity. It will also discuss the mistakes and successes to meet the unique goals, especially when meeting the thermal proof load.

  8. Author Details

    African Journals Online (AJOL)

    Visemih, Willium Muffee. Vol 9, No 2 (2001) - Articles The Role Of Internal Control In The Rural Development Of Cameroon: The Case Of The South West Development Authority (Soweda) Abstract. ISSN: 0856-6372. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's ...

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    Author Details. Journal Home > Advanced Search > Author Details. Log in or Register to get access to full text downloads. ... Abstract PDF · Vol 3, No 6 (2011) - Articles Mixed convection flow and heat transfer in a vertical wavy channel containing porous and fluid layer with traveling thermal waves. Abstract PDF · Vol 3, No 8 ...

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    Author Details. Journal Home > Advanced Search > Author Details. Log in or Register to get access to full text downloads. ... Singh, J. Vol 3, No 2 (2011) - Articles Plane waves in a rotating generalized thermo-elastic solid with voids. Abstract PDF. ISSN: 2141-2839. AJOL African Journals Online. HOW TO USE AJOL.

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    Author Details. Journal Home > Advanced Search > Author Details. Log in or Register to get access to full text downloads. ... Vol 12 (2008) - Articles On the wave equations of shallow water with rough bottom topography. Abstract · Vol 14 (2009) - Articles Energy generation in a plant due to variable sunlight intensity

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    Author Details. Journal Home > Advanced Search > Author Details. Log in or Register to get access to full text downloads. ... Iliopsoas haematoma in a rugby player. Abstract PDF · Vol 29, No 1 (2017) - Articles The use of negative pressure wave treatment in athlete recovery. Abstract PDF. ISSN: 2078-516X. AJOL African ...

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    Author Details. Journal Home > Advanced Search > Author Details. Log in or Register to get access to full text downloads. ... Ismail, A. Vol 9, No 3S (2017): Special Issue - Articles Investigate of wave absorption performance for oil palm frond and empty fruit bunch at 5.8 GHz. Abstract PDF · Vol 9, No 3S (2017): Special Issue ...

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    Author Details. Journal Home > Advanced Search > Author Details. Log in or Register to get access to full text downloads. ... Isa, M.F.M.. Vol 9, No 3S (2017): Special Issue - Articles Experimental and numerical investigation on blast wave propagation in soil structure. Abstract PDF · Vol 9, No 3S (2017): Special Issue - ...

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    Author Details. Journal Home > Advanced Search > Author Details. Log in or Register to get access to full text downloads. ... No 3S (2017): Special Issue - Articles Experimental and numerical investigation on blast wave propagation in soil structure. Abstract PDF · Vol 9, No 3S (2017): Special Issue - Articles Simulation on ...

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    Author Details. Journal Home > Advanced Search > Author Details. Log in or Register to get access to full text downloads. ... to blast loadings. Abstract PDF · Vol 9, No 3S (2017): Special Issue - Articles Experimental and numerical investigation on blast wave propagation in soil structure. Abstract PDF. ISSN: 1112-9867.

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    Author Details. Journal Home > Advanced Search > Author Details. Log in or Register to get access to full text downloads. ... The use of negative pressure wave treatment in athlete recovery. Abstract PDF · Vol 29, No 1 (2017) - Articles The prevalence, risk factors predicting injury and the severity of injuries sustained during ...

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    Author Details. Journal Home > Advanced Search > Author Details. Log in or Register to get access to full text downloads. ... Vol 29, No 1 (2017) - Articles The use of negative pressure wave treatment in athlete recovery. Abstract PDF · Vol 29, No 1 (2017) - Articles The prevalence, risk factors predicting injury and the ...

  1. European agreement on James Webb Space Telescope's Mid-Infrared Instrument (MIRI) signed

    Science.gov (United States)

    2004-06-01

    Artist's impression of the JWST hi-res Size hi-res: 1601 kb Credits: ESA Artist's impression of the JWST An artist's impression of the selected design for the JWST spacecraft. Northrop Grumman and Ball Aerospace are the prime contractors for JWST. Artist's impression of the JWST Credits: ESA Artist's impression of the JWST An artist's impression of the selected design for the JWST spacecraft. Northrop Grumman and Ball Aerospace are the prime contractors for JWST. Observing the first light, the James Webb Space Telescope (JWST) will help to solve outstanding questions about our place in the evolving Universe. MIRI, the Mid-Infrared Instrument, is one of the four instruments on board the JWST, the mission scheduled to follow on the heritage of Hubble in 2011. MIRI will be built in cooperation between Europe and the United States (NASA), both equally contributing to its funding. MIRI’s optics, core of the instrument, will be provided by a consortium of European institutes. According to this formal agreement, ESA will manage and co-ordinate the whole development of the European part of MIRI and act as the sole interface with NASA, which is leading the JWST project. This marks a difference with respect to the previous ESA scientific missions. In the past the funding and the development of the scientific instruments was agreed by the participating ESA Member States on the basis of purely informal arrangements with ESA. In this case, the Member States involved in MIRI have agreed on formally guaranteeing the required level of funding on the basis of a multi-lateral international agreement, which still keeps scientists in key roles. Over the past years, missions have become more complex and demanding, and more costly within an ever tighter budget. They also require a more and more specific expertise which is spread throughout the vast European scientific community. As a result, a new management procedure for co-ordination of payload development has become a necessity to

  2. Authoring Tools

    Science.gov (United States)

    Treviranus, Jutta

    Authoring tools that are accessible and that enable authors to produce accessible Web content play a critical role in web accessibility. Widespread use of authoring tools that comply to the W3C Authoring Tool Accessibility Guidelines (ATAG) would ensure that even authors who are neither knowledgeable about nor particularly motivated to produce accessible content do so by default. The principles and techniques of ATAG are discussed. Some examples of accessible authoring tools are described including authoring tool content management components such as TinyMCE. Considerations for creating an accessible collaborative environment are also covered. As part of providing accessible content, the debate between system-based personal optimization and one universally accessible site configuration is presented. The issues and potential solutions to address the accessibility crisis presented by the advent of rich internet applications are outlined. This challenge must be met to ensure that a large segment of the population is able to participate in the move toward the web as a two-way communication mechanism.

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    African Journals Online (AJOL)

    Seeking Behavior Towards Dysmenorrhea among Female Students of a Private University in Ogun State, Nigeria Abstract PDF. ISSN: 2320-2041. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Journal Home > Advanced Search > Author Details. Log in or Register ... (2013) - Articles Technical Note: Development of a Photobioreactor for Microalgae Culture ... Design, Construction and Evaluation of Motorized Okra Slicer Abstract PDF ...

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    Monitoring on Attitudes toward Internet Fraud among Undergraduate Students of Obafemi Awolowo University, Ile-Ife Abstract PDF. ISSN: 2070-0083. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    , Incubators and the Effects of a Spray-Disinfectant - A Quarterly Ammonium Compound Abstract. ISSN: 1116-1043. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    676X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News. OTHER RESOURCES.

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    , happiness, hope and marital satisfaction among married people in Makurdi Metropolis, Nigeria Abstract. ISSN: 1596-9231. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    communication-style and parental neglect as predictors of aggressive tendencies among Secondary School adolescents. Abstract. ISSN: 0189-0263. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Journal Home > Advanced Search > Author Details. Log in or Register to ... No 1 (2014) - Articles Knowledge and Attitudes towards Basic Cardiopulmonary Resuscitation (CPR) among Community Nurses in Remo Area of Ogun State, Nigeria

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    Mental State Examination and the Montreal Cognitive Assessment Test in schizophrenia. Abstract PDF. ISSN: 2078-6786. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    ” Passages in the Context of Homosexuality Controversy: A Nigerian Perspective Abstract PDF. ISSN: 2141-7040. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    plant interactions and arthropod trophic structure in an endangered grassland in the Free State province, South Africa Abstract. ISSN: 1022-0119. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Journal Home > Advanced Search > Author Details. Log in or Register to get ... Optical bus of centralized relay protection and automation system of medium voltage switchgear for data collection and transmission. Abstract PDF. ISSN: 1112- ...

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    Journal Home > Advanced Search > Author Details. Log in or ... The prevention of mother-to-child HIV transmission programme and infant feeding practices ... Evaluation of a diagnostic algorithm for smear-negative pulmonary tuberculosis in ...

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    Journal Home > Advanced Search > Author Details ... Design and Implementation of an M/M/1 Queuing Model Algorithm and its Applicability in ... Vehicle Identification Technology to Intercept Small Arms and Ammunition on Nigeria Roads

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    509X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News. OTHER RESOURCES.

  18. Revisiting the Classic Moby Dick: The Environmental Significance of the Narrative in the Light of International Environmental Law on the Preservation of the Whaling Marine Life

    Directory of Open Access Journals (Sweden)

    Ana Cristina Alves de Paula

    2016-12-01

    Full Text Available This article aims to analyze the environmental significance of Moby Dick, narrative that, in the mid-nineteenth century, warned, indirectly, on the need to preserve nature against the excesses of whaling. For this, we analyzed the main regulations that composes the environmental protection regime for whaling marine life, one of which allowed exceptions to the prohibition of hunting, based both on alleged scientific research needs as the claim of cultural practices, and the decision of the ICJ in the case brought by Australia in face of Japan.

  19. Authors' Response:

    Directory of Open Access Journals (Sweden)

    E Auger

    2012-03-01

    Full Text Available In this article, the authors suggest that one method for increasing awareness of the benefits of data sharing can be affected by administering a survey, hopefully encouraging either a minority or majority influence on other members of the behavioural science community. The authors describe the process for creating such a survey and provide their survey, although untested. This is a well-timed article as the existing literature on social and behavioural science data is quite thin. The majority/minority influence of norms is a nice theoretical construct to explore. This is definitely one approach to increase awareness of the benefits of data sharing.

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    Manga, A.A.. Vol 10, No 1 (2017) - Articles Effect of different concentrations of aqueous Ascophyllum nodosum extract on flowering and fruiting in some vegetables. Abstract PDF. ISSN: 2006-6996. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Manga, Anicet. Vol 11, No 5 (2017) - Articles Le champignon arbusculaire Glomus aggregatum améliore la nutrition minérale de Acacia seyal soumis au stress salin progressif. Abstract PDF. ISSN: 1997-342X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More ...

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    Manga, SB. Vol 29, No 2 (2008) - Articles Larvicidal efficacy of stock Bacillus sphaericus on local species of Anopheles mosquito in Sokoto, Nigeria Abstract. ISSN: 1117-4145. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Manga, T. Tiki. Vol 8, No 2 (2000) - Articles Chemical composition of Ricinodendron heudelotii: An indigenous fruit tree in southern Cameroon Abstract. ISSN: 2072-6589. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms ...

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    Egah, DZ. Vol 54, No 2 (2008) - Articles Poliomyelitis: An Assessment of the Knowledge of Women in Jos Nigeria and Implications for its Global Eradication Early 21st Century Abstract. ISSN: 0189-0964. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    Jombo, GTA. Vol 54, No 2 (2008) - Articles Poliomyelitis: An Assessment of the Knowledge of Women in Jos Nigeria and Implications for its Global Eradication Early 21st Century Abstract. ISSN: 0189-0964. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    Fatiregun, AA. Vol 7, No 2 (2008) - Articles Poliomyelitis in Osun State, Nigeria: Two Confirmed Cases After 6 years Without Polio Abstract. ISSN: 1595-8272. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions ...

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    Eggers, R. Vol 84, No 10 (1994) - Articles Eradication of poliomyelitis in South Africa Abstract PDF. ISSN: 0256-95749. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News. OTHER ...

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    Adeyemo, Lateef Kayode. Vol 13 (2017) - Articles Legalising same sex marriage and cloning: a need for ethical consideration. Abstract PDF. ISSN: 1597-474X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Uzoma, EF. Vol 1, No 3 (2010) - Articles Challenges and Implications of Genesis 2:18 – 24 on Same-Sex Marriage for the Contemporary Society Abstract PDF. ISSN: 2006-5442. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Wynchank, Dora. Vol 9, No 2 (2006) - Articles Guest Editorial Psychiatry and same sex marriage: are we involved? Abstract PDF. ISSN: 1994-8220. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Odiase-Alegimenlen, OA. Vol 3, No 1 (2014) - Articles Same sex marriage: Nigeria at the middle of western politics. Abstract PDF. ISSN: 2304-8239. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Van Staden, A. Vol 23, No 3 (2017) - Articles Self-reported symptoms of eating disorders amongst university dance students. Abstract. ISSN: 1117-4315. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of ...

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    Cottle, Edward. Vol 7, No 1 (2003) - Articles Realising the right of access to water: Pipe dream or watershed? Abstract PDF. ISSN: 2077-4907. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Elbusaidy, Hemed. Vol 4, No 2 (2015) - Articles Variant Anatomy of Intracranial Part of Middle Meningeal Artery in a Kenyan Population Abstract PDF. ISSN: 2305-9478. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Hurst, NL. Vol 47, No 5 (1973) - Articles Communication between Paranasal Sinuses and Meninges after Trauma Abstract PDF. ISSN: 0256-95749. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Okolie, CJ. Vol 7, No 1 (2012) - Articles Transformation of Shuttle Radar Topography Mission (SRTM) Digital Elevation Data to Nigerian Height System Abstract. ISSN: 1597-8826. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Adzandeh, EA. Vol 7, No 1 (2012) - Articles Transformation of Shuttle Radar Topography Mission (SRTM) Digital Elevation Data to Nigerian Height System Abstract. ISSN: 1597-8826. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Ismagilov, I.I.. Vol 9, No 2S (2017): Special Issue - Articles General method of synthesis by PLIC/FPGA digital devices to perform discrete orthogonal transformations. Abstract PDF. ISSN: 1112-9867. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Koffi, E. Vol 80 (2014) - Articles Evaluation des proprietes antioxidantes et biologiques de farines infantiles a base d'igname/soja/sources vegetales de mineraux. Abstract PDF. ISSN: 1997-5902. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    solution. Abstract PDF. ISSN: 1996-0786. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News.

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    Ngozi-Olehi, LC. Vol 9, No 1 (2011) - Articles Chemical Education: A Tool for Wealth Creation from Waste Management Abstract. ISSN: 1596-8308. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Fotedar, R. Vol 33, No 1 (2011) - Articles Seasonal variations of agar extracted from different life stages of Gracilaria cliftonii (Gracilariales, Rhodophyta) from Western Australia Abstract. ISSN: 1814-232X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    Singh, Jai Govind. Vol 7, No 3 (2015): Supplement - Articles Impact of plug-in electric vehicles on voltage unbalance in distribution systems. Abstract PDF. ISSN: 2141-2839. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms ...

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    Osula, FO. Vol 6, No 1-2 (2014) - Articles Sub-acute hepatotoxicity of Pausinystalia yohimbe bark extract (Burantashi) in male albino rats (Rattus novergicus) Abstract. ISSN: 2251-0079. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Oliha, FO. Vol 33, No 2 (2014) - Research papers. Web Portal Usability among Nigerian University Students: A Case Study of University Of Benin, Nigeria Abstract PDF. ISSN: 2467-8821. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Quaye-Ballard, J A. Vol 27, No 2 (2007) - Articles Usability testing: using “think aloud” method in testing cartographic product. Abstract PDF. ISSN: 0855-0395. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions ...

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    Odubamowo, Kehinde Hussein. Vol 34, No 2 (2017) - Articles Dysmenorrhea among female students at a teaching hospital in South‑Western Nigeria Abstract PDF. ISSN: 0189-5117. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Ugboajah, PKN. Vol 9 (2012) - Articles “We Saw No Real Outstanding Leaders”: Britain's Perception of Nigerian Nationalist Class in Colonial Nigeria Abstract. ISSN: 1597-3778. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Zu, YG. Vol 60 (2007) - Articles Supercritical Fluid Extraction of Seed Oil from Chinese Licorice Glycyrrhiza uralensis Fisch.): Chemical Composition and Antibacterial Activity Abstract PDF. ISSN: 0379-4350. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    Ezeja, Maxwell I. Vol 53, No 3 (2017) - Articles Antioxidant, anti-inflammatory and antinociceptive activities of methanolic extract of Justicia secunda Vahl leaf. Abstract PDF. ISSN: 2090-2948. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Koona, OES. Vol 9, No 2 (2012) - Articles Effect of the Aqueous Extract of Justicia insularis T. Anders (Acanthaceae) on Ovarian Folliculogenesis and Fertility of Female Rats Abstract PDF. ISSN: 0189-6016. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    Murluki, AW. Vol 14, No 2 (2012) - Articles Effect of rain water harvesting and drip irrigation on crop performance in an arid and semi-arid environment. Abstract. ISSN: 1561-7645. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Imtiyaz, M. Vol 27, No 2 (2007) - Articles Yield, irrigation production efficiency and economic returns of broccoli under variable drip irrigation and lateral spacing. Abstract PDF. ISSN: 0855-0395. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Medugu, D W. Vol 18, No 2 (2006) - Articles Design and development of solar still for effectiveness in eliminating microbial contamination and salt in Mubi, Adamawa State, Nigeria Abstract PDF. ISSN: 1595-0611. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More ...

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    Osarolube, E. Vol 7, No 2 (2008) - Articles Single effect green house type solar still for portable water supply. Abstract. ISSN: 1118-1931. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact ...

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    Dublin-Green, M. Vol 7 (2005) - Articles Quality evaluation of yogurts produced commercially In Lagos, Nigeria Abstract PDF. ISSN: 1119-023X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Chukwuma, FO. Vol 4, No 1 (2006) - Articles Use of Straight –Run Gasoline (Srg) as A Leaching Solvent for Oil Palm (Elaeis Guineensis) Kernel Seed Abstract. ISSN: 1596-3497. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Sanusi, AA. Vol 14, No 1 (2008) - Articles Hepatorenal Syndrome In Nigeria: A Review of Pathophysiology, Clinical Features and Management Abstract. ISSN: 0331-3727. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms ...

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    Magendzo, A. Vol 29, No 2 (2011) - Articles Teaching recent history in countries that have experienced human rights violations: Case studies from Chile Abstract. ISSN: 0258-2236. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Asaah, A H. Vol 23, No 1 (2007): - Articles Pan-Africanism, inter-African migration and crisis of national integration in the African novel. Abstract. ISSN: 0855-4412. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Nyangena, KO. Vol 6, No 1-2 (2003) - Articles Jomo Kenyatta: An Epitome of Indigenous Pan-Africanism, Nationalism and Intellectual Production in Kenya Abstract PDF. ISSN: 0850-7902. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Njubi, Francis. Vol 15, No 1 (2001): Media Freedom and Human Rights - Articles New Media, Old Struggles: Pan Africanism, Anti-racism and Information Technology Details. ISSN: 0256-004. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Forje, JW. Vol 6, No 1-2 (2003) - Articles Self-Determination, Nationalism, Development and Pan-Africanism Stuck on the Runway: Are Intellectuals to be Blamed? Abstract PDF. ISSN: 0850-7902. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    border life, pan-africanism, and identity in Ahmadou Kourouma's novels. Abstract. ISSN: 0254-4296. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Paul, Fintan. Vol 5, No 1 (2017) - Articles Government expenditure and economic growth nexus: Wagner's law or Keynesian hypothesis for Tanzania? Abstract PDF. ISSN: 1821-8148. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Qi, Qing. Vol 29, No 2 (2017) - Articles Psychological health among Chinese college students: a rural/urban comparison. Abstract. ISSN: 1728-0583. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Sumera, Matthew. Vol 12, No 1-2 (2015) - Articles Johnson, Bruce & Martin Cloonan (2009). Dark Side of the Tune: Popular Music and Violence Abstract. ISSN: 2070-626X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms ...

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    Adido, J. Vol 16, No 1 (2008) - Articles Vision of Strabismic Children in Ilorin, Nigeria Abstract PDF. ISSN: 2468-8363. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News. OTHER ...

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    Elmehashi, MO. Vol 9, No 4 (2014) - Articles Hysteroscopy in Libyan women with Recurrent Pregnancy Loss Abstract. ISSN: 1858-5051. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact ...

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    Laleye, F O. Vol 6, No 1 (2007) - Articles In vitro Heparin Precipitation in the Plasma of Euthyroid women with Recurrent Miscarriage and Unexplained Infertility Abstract. ISSN: 1595-8272. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Osei-Bagyina, A. Vol 28, No 2 (2008) - Articles Assessment and Management of Articulation and Phonological Disorders in School Children in Ghana Abstract PDF. ISSN: 0855-0395. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Hamisa, M. Vol 51, No 3 (2015) - Articles Role of Doppler US and MRI in diagnosis of placenta accreta. Abstract PDF. ISSN: 2090-2948. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact ...

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    Korah, TE. Vol 50, No 3 (2014) - Articles Role of serum glypican-3 in the diagnosis and differentiation of small hepatocellular carcinoma from hepatitis-C virus cirrhosis. Abstract PDF. ISSN: 2090-2948. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    Widyawaruyanti, A. Vol 4, No 3 (2007) - Articles Apoptosis Inducing Effect Of Andrographolide On TF-47 Human Breast Cancer Cell Line Abstract PDF. ISSN: 0189-6016. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Jordaan, JC. Vol 17, No 3 (2013) - Articles Impact of interest rate changes on South African GDP and households: a combined macroeconomic and social accounting matrix modelling approach. Abstract PDF. ISSN: 1998-8125. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Aniley, B. Vol 1, No 2 (2010) - Articles Service quality attributes affecting passengers' satisfaction with HIGER city bus. Abstract PDF. ISSN: 2410-2393. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Chakraborty, Shankar. Vol 4, No 2 (2012) - Articles A modified principal component analysis-based utility theory approach for optimization of correlated responses of EDM process. Abstract PDF. ISSN: 2141-2839. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More ...

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    Isa, E.D.M.. Vol 9, No 6S (2017) - Articles Silica coated ionic liquid templated mesoporous silica nanoparticles. Abstract PDF. ISSN: 1112-9867. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Mahapatra, S. Vol 2, No 5 (2010) - Articles Modeling, simulation and parametric optimization of wire EDM process using response surface methodology coupled with grey-Taguchi technique. Abstract PDF. ISSN: 2141-2839. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Omokhudu, OO. Vol 2, No 1 (2011) - Articles International Convergence of Accounting Standards: Issues and Challenges Abstract. ISSN: 2141-4343. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Kareem, MK. Vol 22 (2012): 21-22 (2011-2012) - Articles The Nigerian Statements of Accounting Standards and Ribh (Profit) in an Islamic Economy Abstract. ISSN: 2141-9744. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Al-Suqri, MN. Vol 12, No 1-2 (2012) - Articles Toward Virtual Universities in the Sultanate of Oman: Reality, Challenges and Perspectives Abstract PDF. ISSN: 1596-5422. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms ...

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    Ekweariri, CS. Vol 4, No 1-2 (2013) - Articles Synthetic design and the art of virtual reality in theatre and film productions. Abstract PDF. ISSN: 2449-1179. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of ...

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    Xu, H. Vol 9, No 6S (2017) - Articles An external control unit implemented for stimulator ASIC testing. Abstract PDF. ISSN: 1112-9867. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL ...

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    Kumari, N.A.K.G.E.. Vol 7, No 1 (2002) - Articles Appropriate Hydroponic systems for growing tropical leafy vegetables in greenhouse. Abstract. ISSN: 1118-2733. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Oladele, O. I.. Vol 7, No 1 (2002) - Articles Appropriate Hydroponic systems for growing tropical leafy vegetables in greenhouse. Abstract. ISSN: 1118-2733. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of ...

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    Okeke, K.K.. Vol 23, No 1 (2016) - Articles Overview of NoSQL and comparison with SQL database management systems. Abstract. ISSN: 2006-5523. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Luna, AM. Vol 8, No 1 (2008) - Articles From Complementarity to Conflict: A Historical Analysis of Farmer-Fulbe Relations in West Africa Abstract PDF. ISSN: 1562-6997. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Bergh, Luna. Vol 29, No 1 (2011) - Articles Met kerse op met-konstruksies1: 'n Verwysingspuntperspektief Abstract. ISSN: 1607-3614. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL ...

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    Hatami, Homeira. Vol 12, No 1 (2015) - Articles Intrahippocampal administration of Vitamin C and progesterone attenuates spatial earning and memory impairments in multiple sclerosis rats. Abstract. ISSN: 1597-3115. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's ...

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    Ashimi, A.O.. Vol 59, No 4 (2017) - Articles Knowledge of Zika virus disease among reproductive-age women attending a general outpatient clinic in Northern Nigeria Abstract PDF. ISSN: 2078-6204. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Davidson, Kevin. Vol 32, No 1 (2012) - Articles Stylistic traits in South African Jazz Barney Rachabane: a case study. Abstract. ISSN: 0258-509X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Coplan, DB. Vol 33, No 1 (2013) - Articles Thula Mabota: South African Jazz and Popular Music Since 1994. Abstract. ISSN: 0258-509X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact ...

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    Comarof, Jean. Vol 1999, No 3-4 (1999) - Articles Alien-Nation: Zombies, Immigrants and Millennial Capitalism Details. ISSN: 0850-8712. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact ...

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    Krakstad, J-O. Vol 32, No 2 (2010) - Articles Dusky dolphins Lagenorhynchus obscurus and Cape fur seals Arctocephalus pusillus pusillus: fatty acid composition of their blubber and prey species. Abstract. ISSN: 1814-232X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    NENTY, N. JOHNSON. Vol 7, No 3 (2001) - Articles Common errors and perfomance of students in junior secondary mathematics certificate examinations in Cross River State, Nigeria Details PDF. ISSN: 1118-0579. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's ...

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    Johnson, P_NT. Vol 31, No 1 (1998) - Articles Physico-chemical changes during storage of dehydrated plantain slices packaged in two polymeric film pouches. Abstract. ISSN: 0855-0042. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Johnson, Tosin. Vol 13, No 1 (2016) - Articles Antidiabetic effect of Crossopteryx febrifuga methanolic leaf extract in alloxan induced diabetic rats. Abstract. ISSN: 0189-8442. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms ...

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    Clasquin-Johnson, M. Vol 29, No 2 (2009) - Articles The centuries-old dialogue between buddhism and christianity. Abstract PDF. ISSN: 2309-9089. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Johnson, J. Vol 12, No 1 (2009) - Articles Climate Change and Fishery Sustainability in Lake Victoria Abstract. ISSN: 0002-0036. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL ...

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    Johnson-Ajinwo, OR. Vol 8, No 1 (2010) - Articles A Review of the Bio-Activity Relationship of Mistletoes and the Leaves of their Host Trees Abstract. ISSN: 0189-8434. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Johnson, FS. Vol 30, No 1 (2010) - Articles Saccharification of Maize Agrowastes by Cellulolytic Fungi Isolated from Ejura Farms in Ejura, Ghana Abstract PDF. ISSN: 0855-0395. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Nenty, H. Johnson. Vol 4, No 1 (2000) - Articles Gender-typing, Performance and Achievement-related Behaviour in Mathematics by Secondary School Students in Lesotho Abstract. ISSN: 1024-4190. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Mahtar, S.N.A.M.. Vol 9, No 5S (2017): Special Issue - Articles Trust aware recommender system with distrust in different views of trusted users. Abstract PDF. ISSN: 1112-9867. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Gilban, Hussa M. Vol 24, No 4 (2005) - Articles Simultaneous post traumatic bilateral cervico-trochanteric femoral neck fractures in a child: a case report. Abstract PDF. ISSN: 0189-160X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Yabefa, ET. Vol 35, No 2 (2016) - Computer, Telecommunications, Software, Electrical & Electronics Engineering MULTILEVEL BUCK CONVERTER FOR AUTOMOTIVE ELECTRICAL LOAD Abstract PDF. ISSN: 2467-8821. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Ghassemi, A. Vol 8, No 3 (2016): Special Issue - Articles Determining a piston's top dead center (TDC) in an automobile using installed piezoelectric on a vibrating beam. Abstract PDF. ISSN: 1112-9867. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    Ally, M.M.T.M.. Vol 107, No 4 (2017) - Articles Systemic lupus erythematosus: A possible cause of non-alcoholic Wernicke's encephalopathy. Abstract PDF. ISSN: 0256-95749. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Musenge, E. Vol 21, No 4 (2009) - Articles Common lower extremity injuries in female high school soccer players in Johannesburg east district. Abstract PDF. ISSN: 2078-516X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Fuzzy inference system of Tsukamoto method in decision making on determination of insurance premium amount for due damages of flood natural disaster. Abstract PDF. ISSN: 1112-9867. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Wong, K.L.. Vol 10, No 1S (2018): Special Issue - Articles Key performance indicators for measuring sustainability in health care industry in Malaysia Abstract PDF. ISSN: 1112-9867. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Dannon, E. Vol 9, No 2 (2015) - Articles Efficacité de l'agent antagoniste Trichoderma harzianum sur Fusarium oxysporum f. sp. lycopersiciagent pathogène de la tomate. Abstract PDF. ISSN: 1997-342X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    Otokunefor, TV. Vol 4, No 1 (2002) - Articles The incidence of Salmonella and Vibrio species as actiological agents of diarrhoea in water environment in rivers and Bayelsa state, Nigeria Abstract · AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Otukunefor, TV. Vol 6, No 3 (2012) - Articles Bacterial species isolated from water bodies in Rivers and Bayelsa States are possible aetiological agents of diarrhoea. Abstract. ISSN: 0795-3038. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Millogo/Rasolodimby, J. Vol 3, No 4 (2009) - Articles Plantes utilisées pour attirer les essaims de l'abeille domestique (Apis mellifera adansonii Latreille) au Burkina Faso Abstract PDF. ISSN: 1997-342X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    Saleh, S. Vol 9, No 6S (2017) - Articles An analysis on compensation of claims regarding to personal Injury and loss of earning on several court cases. Abstract PDF. ISSN: 1112-9867. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Mukwabi, D.M.. Vol 94, No 1 (2017) - Articles Contamination of the minnow Rastrineobola argenta, through handling at landing sites and retail markets around Lake Victoria Abstract. ISSN: 0012-835X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    Craddock, Michelle. Vol 32, No 3 (2009) - Articles Reflexivity and the Grothendieck property for positive tensor products of Banach lattices-II Abstract. ISSN: 1727-933X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Smith, G. Vol 21, No 6 (2007) - Articles Print based learning might still be the answer to the digital divide. Abstract. ISSN: 1011-3487. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL ...

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    Akidi, Juliana Obiageri. Vol 50, No 1 (2017) - Articles Bridging the digital divide: the potential role of the National Library of Nigeria Abstract. ISSN: 0029-0122. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions ...

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    Ugboma, Margaret U. Vol 3, No 1-2 (2012) - Articles Bridging the digital divide: with special reference to Nigeria Abstract PDF. ISSN: 2360-994X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Kamau, SN. Vol 1, No 1 (2007) - Articles A digital divide: Kiswahili holds the key. Abstract PDF. ISSN: 1998-1279. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News. OTHER ...

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    Mphinyane, Sethunya Tshepho. Vol 30, No 1 (2005) - Articles NEPAD and the Digital Divide: Silent Marginalised Minorities in the age of ICT: The Case of Botswana Abstract. ISSN: 0850-3907. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Ate, Asan Andrew. Vol 9, No 3 (2012) - Articles Communication Satellite: Nigeria's Efforts at Bridging Digital Divide Abstract. ISSN: 1813-2227. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Bennett, M. Vol 5, No 3 (2005) - Articles Crossing the digital divide: the contribution of information technology to the professional performance of malaria researchers in Africa Abstract PDF. ISSN: 1680-6905. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More ...

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    Kruger, L. Vol 44 (2016) - Articles Parental influence on consumer and purchase behaviour of Generation Y Abstract PDF. ISSN: 0378-5254. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact ...

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    Adams, L. Vol 40 (2010) - Articles Uncertainty in information seeking behaviour in the virtual playground of Generation Y students at Stellenbosch University Abstract. ISSN: 1025-8892. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Ugoji, FN. Vol 14, No 1 (2011) - Articles Self-Efficacy and Locus of Control as Predictors of Academic Procrastination Among Undergraduates in a Nigerian Abstract · AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Gebremedhin, Mussie Mezgebo. Vol 10, No 1 (2016) - Articles Procrastination in Recognizing the Rights of Domestic Workers in Ethiopia Abstract PDF. ISSN: 1998-9881. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms ...

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    Adesina, FT. Vol 19, No 1 (2011) - Articles Influence of academic procrastination and personality types on academic achievement and efficacy of in-school adolescents in Ibadan Abstract. ISSN: 1117-1421. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    Azure, JA. Vol 10, No 1 (2011) - Articles Correlates of course anxiety and academic procrastination in higher education. Abstract PDF. ISSN: 1596-6224. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of ...

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    Nwafor, A. U.. Vol 36, No 2 (2017) - Articles Experimental validation of optimum resistance moment of concrete slabs reinforced with carbon fibre-reinforced plastic. Abstract PDF. ISSN: 2467-8821. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Dzasu, WE. Vol 4, No 1 (2011) - Articles Effects of Groundnut Husk Ash-blended Cement on Chemical Resistance of Concrete Abstract PDF. ISSN: 1596-6035. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Indian Academy of Sciences (India)

    user1

    Astr. (2012) 33, 419–420. Author Index. 419. AGGARWAL SUNNY. Photoionization Cross-Section of Chlorine-like Iron, 291. AMBASTHA ASHOK see Das, A. C., 1. ARAKIDA HIDEYOSHI. Effect of Inhomogeneity of the Universe on a Gravitationally. Bound Local System: A No-Go Result for Explaining the Secular Increase in.

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    Umar, L A. Vol 24, No 3 (2006) - Articles Survey Of Ketosis In Lactating Wadara Cows Abstract. ISSN: 0794-4845. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News. OTHER ...

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    Langaney, A. Vol 1, No 2 (2009) - Articles Critical Short Report: Human population genetics and “ancestrality” business - Short report. Abstract PDF. ISSN: 1737-8176. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Cinelli, G. Vol 28, No 1 (2015) - Articles La funzione etica e catartica della rappresentazione della sofferenza in storia della colonna infame di manzoni. Abstract PDF. ISSN: 2225-7039. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Adewumi, A. Vol 1, No 2 (2009) - Articles Relationship Between Plasma Homocysteine and Vitamin B12 Levels in Clinically Diagnosed Cases of Cardiovascular Accident in Lagos, Nigeria Abstract PDF. ISSN: 2076-6270. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Akinsola, OJ. Vol 14, No 1-2 (2014) - Articles Plasma Homocysteine and Haematological Changes in Infertile Women in Lagos, Nigeria Abstract. ISSN: 1597-7889. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Abd Elmonem, Sawsan M. Vol 19, No 1 (2018) - Articles Abnormal maternal biomarkers of homocysteine and methionine metabolism and the risk of congenital heart defects. Abstract PDF. ISSN: 1110-8630. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More ...

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    Abudu, O. Vol 1, No 1 (2009) - Articles Homocysteine Levels in Nigerian Women with Pre-eclampsis/Eclampsia Abstract PDF. ISSN: 2076-6270. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Agada, N. Vol 1, No 2 (2009) - Articles Relationship Between Plasma Homocysteine and Vitamin B12 Levels in Clinically Diagnosed Cases of Cardiovascular Accident in Lagos, Nigeria Abstract PDF. ISSN: 2076-6270. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's ...

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    Oladipo, OO. Vol 30, No 5 (2011) - Articles Plasma Homocysteine Level and its Relationship to Clinical Profile in Parkinson's Disease Patients at the Lagos University Teaching Hospital Abstract PDF. ISSN: 0189-160X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's ...

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    Kanjou, Y. Vol 1, No 2 (2009) - Articles Original Synthetic Report: Study of Neolithic human graves from Tell Qaramel in North Syria Abstract PDF. ISSN: 1737-8176. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Agu, KC. Vol 19, No 3 (2015) - Articles Influence of Spent-Engine Oil on Hematology, Renal and Liver Status of Auto- Mechanics of Benin-City, Nigeria Abstract PDF. ISSN: 1119-8362. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Mbam, BCE. Vol 19, No 1 (2013) - Articles Traffic simulation for mixed traffic systems. Abstract. ISSN: 1118-0579. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News. OTHER ...

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    Onwubiko, HA. Vol 8, No 3 (2011) - Articles Metal induced conformational changes of prion protein into Β-sheet isoforms similar to amyloid. Abstract. ISSN: 1597-3115. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Tutu, E. Vol 27, No 1 (2007) - Articles Friction coefficient of maize, cowpea and groundnuts on different structural surfaces. Abstract PDF. ISSN: 0855-0395. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of ...

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    Aveyire, J. Vol 27, No 1 (2007) - Articles Friction coefficient of maize, cowpea and groundnuts on different structural surfaces. Abstract PDF. ISSN: 0855-0395. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions ...

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    Amao, A.O. Vol 4, No 1 (2009) - Articles Natural foods and feeding habits of the African honey bee Apis mellifera adansonii Latrielle (1804) in Zaria, northern Nigeria Abstract PDF. ISSN: 1597-6343. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Ademolu, A. A.. Vol 11, No 1-2 (2015) - Articles Laboratory Evaluation of Insecticidal Activities of Some Botanicals against Four Insect Pests of Honey Bees (Apis mellifera L.) Abstract PDF. ISSN: 0331-5428. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    Achou, M. Vol 28 (2014) - Articles Etude de la diversité morphométrique de deux populations d'abeilles domestiques (Apis mellifera intermissa et Apis mellifera sahariensis) du sud Algérien Abstract PDF. ISSN: 2352-9717. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Fasasi, KA. Vol 8 (2010) - Articles Effect of age of honeybee queens of Apis mellifera adansonii (Hymenoptera: apidae) on the rate of brood production in modern bee-hives. Abstract. ISSN: 1596-972X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    Fasasi, KA. Vol 13, No 1 (2011) - Articles Studies on the life cycle and morphometrics of honeybees, Apis Mellifera adansonii (Hymenoptera: Apidae) in a Mangrove Area of Lagos, Nigeria Abstract PDF. ISSN: 0794-4896. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Alkan, M. Vol 20, No 10 (2017) - Articles Neutrophil lymphocyte ratio predicts postoperative pain after orthognathic surgery. Abstract PDF. ISSN: 1119-3077. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions ...

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    Jones, T. Vol 96 (2007) - Articles Cassin\\'s hawk-eagle Spizaetus africanus in Ndundulu Forest: a first record for Tanzania, with biogeographical implication. Abstract. ISSN: 1026-1613. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Idrus, Z. Vol 9, No 5S (2017): Special Issue - Articles Visual analytics: designing flexible filtering in parallel coordinate graph. Abstract PDF. ISSN: 1112-9867. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions ...

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    Ewing, H. Vol 2, No 2 (2015): Series F - Articles Abstract: Use of E-Learning to Advance Nursing Education in Rwanda Abstract PDF. ISSN: 2305-2678. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Polat, Nedim. Vol 13, No 3 (2017) - Articles Intestinal obstruction due to ileal metastasis of Ewing's sarcoma. Abstract PDF. ISSN: 1687-4137. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact ...

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    Batista, Vasco. Vol 41, No 1 (2006) - Articles Spring diet and trophic partitioning in an alpine lizard community from Morocco Abstract. ISSN: 2224-073X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of ...

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    Dosunmu, OJ. Vol 7, No 23 (2008) - Articles Hatchability of chicken eggs as influenced by turning frequency in hurricane lantern incubator. Abstract PDF. ISSN: 1684-5315. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms ...

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    Okayi, RG. Vol 2, No 2 (2010) - Articles Acute Toxicity of Glyphosate on Clarias Gariepinus Fingerlings Abstract PDF. ISSN: 2141-1778. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL ...

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    Ambali, SF. Vol 11, No 2 (2013) - Articles Haematogical changes induced by subchronic glyphosate exposure: Ameliorative effect of zinc in Wistar rats. Abstract PDF. ISSN: 1595-093X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Udofot, Cordelia Bukola. Vol 21, No 6 (2017) - Articles Mycostimulation in a glyphosate treated arable soil: implications on the yield and agronomic characters of Talinum fruticosum (L.) Juss Abstract PDF. ISSN: 1119-8362. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Ainerua, M O. Vol 18, No 2 (2014) - Articles Histopathological changes in the Brain Tissue of Africa Catfish exposure to Glyphosate Herbicide Abstract PDF. ISSN: 1119-8362. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms ...

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    Matlakala, MC. Vol 19 (2013): Supplement 1 – September - Articles Video conference teaching at an Open Distance Learning (ODL) university in South Africa: Analysis of benefits and drawbacks. Abstract. ISSN: 1117-4315. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Steyn, Herman. Vol 23, No 1 (2016) - Articles Exploring the influence of instant messaging and video conferencing on the quality of project communication. Abstract PDF. ISSN: 2415-0487. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Nagel, F.O.. Vol 78, No 10 (1990) - Articles Childhood near-drowning - a 12-year retrospective review. Abstract PDF. ISSN: 0256-95749. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact ...

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    Ijeomah, HM. Vol 7, No 2 (2015) - Articles Utilization of tortoise (Chelonoides Nigra, Quoy and Gaimard, 1824) in five selected communities in Udu Local Government Area of Delta State, Nigeria Abstract PDF. ISSN: 2141-1778. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Craig, AJFK. Vol 8, No 2 (1973) - Articles Evidence for Thermoregulation in the Tortoise Chersine Angulata Abstract PDF. ISSN: 2224-073X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact ...

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    Ramsay, Scot L. Vol 37, No 1 (2002) - Articles Decapitation of the tortoise Chersina angulata: Is the large grey mongoose a headhunter? Abstract. ISSN: 2224-073X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Moonsamy, Nedine. Vol 43, No 3 (2016) - Articles A “funny” feeling: laughter and nostalgia in Alex Latimer's The Space Race Abstract. ISSN: 0376-8902. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of ...

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    Okune, Sunday Tasen. Vol 8, No 2 (2011) - Articles Themes of Idealism and Nostalgia in Negritude Poetry Abstract. ISSN: 1813-2227. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL ...

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    Ethylhexyl) phthalate exposed adult Wistar Rats Abstract. ISSN: 1596-2407. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Kindler, D. Vol 40, No 4 (2015) - Articles An assessment of the reproductive biology of the Marico barb Barbus motebensis from the upper Groot Marico catchment, South Africa Abstract. ISSN: 1727-9364. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    Cultural Research: A Case of the Abutia Communities in Ghana Abstract. ISSN: 0855-4412. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms ...

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    Namukobe, Jane. Vol 10, No 6 (2016) - Articles Hippeastrum hybridum anthocyanins as indicators of endpoint in acid – base titrations. Abstract PDF. ISSN: 1997-342X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Assa, Rebecca Rachel. Vol 10, No 3 (2016) - Articles Variation des paramètres biochimiques de l'eau de coco (Cocos nucifera L.) issu de la culture in vitro pendant la période de stockage. Abstract PDF. ISSN: 1997-342X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    NIMENIBO-UADIA, Rachel. Vol 15, No 1 (2003) - Articles Effect of aqueous extract of Canavalia ensiformis seeds on hyperlipidaemia and hyperketonaemia in alloxan-induced diabetic rats. Abstract PDF. ISSN: 0795-8080. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Ogbimi, FE. Vol 4, No 4 (2007) - Articles Promoting Sustainable Economic Growth And Industrialisation: Solution To Mass Unemployment And Poverty Abstract PDF. ISSN: 0189-6016. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Delwaide, Anne-Cécile. Vol 14, No 1 (2017) - Articles Ghanaian Consumers' Attitudes toward Cisgenic Rice: Are all Genetically Modified Rice the Same? Abstract PDF. ISSN: 0855-6768. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Bekele, Y. Vol 15, No 2 (2012) - Articles The Implications of federalism and decentralisation on socio-economic conditions in Ethiopia Abstract PDF. ISSN: 1727-3781. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Atanda, FA. Vol 8, No 2 (2010) - Articles Fiscal federalism and equity in the state joint local governments' account: Oyo state in focus. Abstract. ISSN: 1596-8308. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Uyi-Ekpen, Ogbeide. Vol 5, No 1 (2016) - Articles Federalism, State Creation and the Minority Ethnic Groups in Nigeria's National Integration Project Abstract PDF. ISSN: 2227-5452. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Odigwe, Dorcas Akhere. Vol 4, No 1 (2015) - Articles Fiscal Federalism and Development In Nigeria Abstract · Vol 4, No 2 (2015) - Articles Nigerian political parties and internal democracy. Abstract. ISSN: 2218-5615. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's ...

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    Boudebane, S. Vol 18 (2008) - Articles Influence de la fatigue thermique et des chocs thermiques sur la tenue au frottement et à l'usure d'un revêtement en acier inoxydable austénitique 304L Abstract PDF. ISSN: 2352-9717. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Ojating, I. Vol 16, No 1 (2010) - Articles Timber trade and marketing in two deregulated timber markets economy in Calabar, Cross River State, Nigeria Abstract PDF. ISSN: 1118-0579. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Gilfillan, K.V.. Vol 108, No 2 (2018) - Articles Heroin detoxification during pregnancy: A systematic review and retrospective study of the management of heroin addiction in pregnancy. Abstract PDF. ISSN: 0256-95749. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's ...

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    Nwachukwu, NJ. Vol 9, No 1 (2013) - Articles Cloud Computing: Key to IT Development in West Africa Abstract PDF. ISSN: 1116-5405. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL ...

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    Okekeokosisi, JohnBosco O.C. Vol 15, No 1 (2015) - Articles Insight into the Utilization of Cloud and Mobile Computing in a service oriented world. Abstract PDF. ISSN: 1116-5405. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Onwubiko, CPC. Vol 10, No 1-2 (2010) - Articles Succession Planning In Academic Libraries In Owerri, Imo State, Nigeria: An Evaluative Study Abstract PDF. ISSN: 1596-5422. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Leichliter, JS. Vol 8, No 2 (2011) - Articles 'Clinics aren't meant for men': Sexual health care access and seeking behaviours among men in Gauteng province, South Africa Abstract PDF. ISSN: 1813-4424. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

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    oesophageal fistula – an unusual presentation. Abstract PDF. ISSN: 2078-676X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of ...

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    Hodgson, R.E.. Vol 23, No 5 (2017) - Articles Awake percutaneous tracheostomy as an alternative to open emergency tracheostomy in a threatened airway. Abstract PDF. ISSN: 2220-1173. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Kodiya, AM. Vol 18, No 1 (2013) - Articles Tracheostomy in Northern Nigeria- A Multicentre Review Abstract PDF. ISSN: 2073-9990. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL ...

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    Okhakhu, AL. Vol 6, No 3 (2012) - Articles Changing indications for paediatric tracheostomy in a Nigerian tertiary hospital. Abstract. ISSN: 0795-3038. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Ijaduola, GTA. Vol 15, No 1 (2010) - Articles Tracheostomy Decannulation: Suprastomal Granulation Tissue in Perspective Abstract PDF. ISSN: 2073-9990. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of ...

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    Kamat, S. Vol 32, No 1 (2016) - Articles Post-tracheostomy tracheo-oesophageal fistula – an unusual presentation. Abstract PDF. ISSN: 2078-676X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Karuga, G. Vol 17, No 1 (2012) - Articles Risk Factors of Early Complications of Tracheostomy at Kenyatta National Hospital Abstract PDF. ISSN: 2073-9990. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions ...

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    Pal, Suryal Kant. Vol 12, No 3 (2017) - Articles A modified procedure for estimating the population mean in two-occasion successive samplings. Abstract PDF. ISSN: 2316-090X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Aminzadeh, F. Vol 23, No 1 (2015) - Articles Using Machine Learning for Land Suitability Classification Abstract PDF. ISSN: 0855-4307. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact ...

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    Motedayen, Nazila. Vol 12, No 47 (2013) - Articles Bioconversion of ferulic acid to vanillin by combined action of Aspergillus niger K8 and Phanerochaete crysosporium ATCC 24725. Abstract PDF. ISSN: 1684-5315. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's ...

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    Akinchan, Narayan T. Vol 9, No 1 (2003) - Articles Identification of Trimer and Dimer of 4-hydroxy-3-methoxy benzaldehyde in crystal structure of Vanillin Abstract PDF. ISSN: 1118-0579. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Olatunji, GA. Vol 2 (1997) - Articles Vanillin derivative spray reagents for identification of organic compounds on thin layer chromatograms. Abstract PDF. ISSN: 1119-0221. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms ...

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    Jhaumeer-Laulloo, S. Vol 4, No 1 (2010) - Articles Structure-activity relationship of Schiff base derivatives of bis(aminophenyl)disulfide and p-vanillin as antimicrobial agents. Abstract PDF. ISSN: 1997-342X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More ...

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    Azmoon, F. Vol 8, No 3 (2016): Special Issue - Articles Hysteresis behavior of seismic isolators in earthquakes near a fault in eccentrically braced frames with vertical and horizontal links. Abstract PDF. ISSN: 1112-9867. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's ...

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    Tetana, ZN. Vol 65 (2012) - Articles The Synthesis of Nitrogen-Doped Multiwalled Carbon Nanotubes Using an Fe-Co/CaCO3 Catalyst Abstract PDF PDF. ISSN: 0379-4350. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms ...

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    Panahandeh, M. Vol 66 (2013) - Articles Oxidized Single-Walled Carbon Nanotubes (SWCNs-COOH) as a New Catalyst for the Protection of Carbonyl Groups as Hydrazones Abstract PDF. ISSN: 0379-4350. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More ...

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    Goshwe, NY. Vol 12 (2013) - Articles Prediction of Path loss Estimate for a Frequency Modulation (FM) Station Using Basic Transmission Loss Model Abstract PDF. ISSN: 1596-292X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Igwue, GA. Vol 12 (2013) - Articles Prediction of Path loss Estimate for a Frequency Modulation (FM) Station Using Basic Transmission Loss Model Abstract PDF. ISSN: 1596-292X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

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    Ogeng'o, J.A. Vol 3, No 2 (2009) - Articles Treatment and outcome of herniated lumbar intervertebral disk in a referral hospital in Kenya Abstract PDF. ISSN: 1994-1072. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Schellack, N. Vol 106, No 10 (2016) - Articles 'Esprit de corps': Towards collaborative integration of pharmacists and nurses into antimicrobial stewardship programmes in South Africa Abstract PDF. ISSN: 0256-95749. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's ...

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    Ugwumba, AAA. Vol 8 (2010) - Articles Effect of feeding frequencies on growth performance of Clarias gariepinus. Abstract. ISSN: 1596-972X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Osinubi, AAA. Vol 6, No 2 (2012) - Articles The Use Of Animals In Endocrine Research: A Synopsis Abstract. ISSN: 2251-0362. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News.

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    Badawi, AAA. Vol 17, No 2 (2010) - Articles Testing Non-Stationarity in Selected Macroeconomic Series from Sudan Abstract. ISSN: 1116-4875. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Oyelekan, A.A.A.. Vol 1, No 1 (2013) - Original Article Psychological well-being of medical students in a state university, Nigeria Abstract PDF. ISSN: 2467-8252. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Osinubi, AAA. Vol 24, No 1 (2014) - Articles Interaction of amodiaquine hydrochloride and antioxidant Vitamin C supplementation on ovarian function in cycling Sprague-Dawley rats. Abstract. ISSN: 0189-2657. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More ...

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    Osinubi, AAA. Vol 13, No 2 (2014) - Articles Assessment of the effects of parenteral quinine on testicular histology and sperm parameters in wistar rats. Abstract PDF. ISSN: 1596-6941. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

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    Abrini, Jamal. Vol 3, No 3 (2006) - Articles Study on antigenotoxic effects of Moroccan medicinal plants and spices using the white/white + somatic assay in Drosophila Abstract. ISSN: 0189-6016. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Mezzoug, Nadya. Vol 3, No 3 (2006) - Articles Study on antigenotoxic effects of Moroccan medicinal plants and spices using the white/white + somatic assay in Drosophila Abstract. ISSN: 0189-6016. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Soares, Juliana Késsia Barbosa. Vol 15, No 50 (2016) - Articles Influence of sweeteners in the biodistribution of radiopharmaceutical and laboratory tests in rats. Abstract PDF. ISSN: 1684-5315. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Nagdee, M. Vol 14, No 3 (2011) - Articles Dementia in intellectual disability: a review of diagnostic challenges. Abstract PDF. ISSN: 1994-8220. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Leitinger, N. Vol 3, No 1 (1998) - Articles Isolation and in-vitro oxidation of human low density lipoproteins. Abstract. ISSN: 1118-2601. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL ...

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    Igweh, JC. Vol 3, No 1 (1998) - Articles Isolation and in-vitro oxidation of human low density lipoproteins. Abstract · Vol 6, No 1 (2001) - Articles Isradipine decreases arterial thrombogenicity in rabbits. Abstract. ISSN: 1118-2601. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Ijaiya, H. Vol 3, No 1 (2014) - Articles Challenges of corporate social responsibility in the Niger delta region of Nigeria Abstract PDF. ISSN: 2467-8392. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    du Toit, J.S. Vol 29, No 2 (2009) - Articles God as father: the representation of the tenth plague in children's bibles. Abstract PDF. ISSN: 2309-9089. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Beekoo, C. Vol 16, No 1 (2010) - Articles Devising a Strategy to Implement an Environmental Management System Based on ISO 14001:2004 in the Hotel Sector Abstract PDF. ISSN: 1694-0342. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Editor,. Vol 4 (2004) - Articles Editorial: Is actuarial science really a science? Abstract. ISSN: 1680-2179. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News. OTHER RESOURCES ...

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    Mbajiorgu, C.C.. Vol 36, No 4 (2017) - Research papers. Prediction of the impacts of climate changes on the stream flow of Ajali River Watershed using SWAT model. Abstract PDF. ISSN: 2467-8821. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Fasina, E.P. Vol 22, No 1 (2015) - Articles Evaluation of a flexible column-based access control security model for medical-based information. Abstract. ISSN: 2006-5523. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Yieke, F. Vol 6, No 2 (2004) - Articles Sexual Harassment in the Workplace: A Case for Linguistic and Sexual Politics? Abstract. ISSN: 1595-0956. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

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    Ighodaro, CAU. Vol 10, No 1&2 (2011) - Articles Electricity infrastructure failure and the development of micro sized enterprises in Nigeria: Evidence from Benin City Abstract PDF. ISSN: 1596-6216. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    Atuanya, E.I. Vol 24, No 2 (2016) - Articles Production of Biosurfactants by Actinomycetes Isolated from Hydrocarbon Contaminated Soils and Ikpoba River Sediments in Benin-City, Nigeria Abstract PDF. ISSN: 0794-5698. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

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    Okolo, BN. Vol 15 (2011) - Articles Effects of Different Carbon Sources on Biosurfactant Production by a Pseudomonas fluorescens Isolate Abstract. ISSN: 1119-2283. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

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    Tirtouil, A. Vol 8, No 3 (2016) - Articles Removal of zinc and cadmium ions from contaminated soils with rhamnolipid biosurfactant produced by Pseudomonas aeruginosa S7PS5 Abstract PDF. ISSN: 1112-9867. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More ...

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    Cinel, B. Vol 14 (2010) - Articles Biosurfactants in Dwarf Mistletoe (Arceuthobium) Abstract. ISSN: 1119-2283. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News. OTHER ...

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    Dhail, Seema. Vol 6, No 6 (2012) - Articles Isolation of biosurfactant-producing marine bacteria. Abstract PDF. ISSN: 1996-0786. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL ...

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    Adesakin, MA. Vol 13, No 1-2 (2013) - Articles An Assessment of Use and Currency of Information on the Undergraduate Students' Web Portal at the University of Ilorin Abstract PDF. ISSN: 1596-5422. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

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    van der Merwe, Helga. Vol 33, No 2 (2016) - Articles Vegetation dynamics after experimental fire disturbance in the arid Succulent Karoo, South Africa Abstract. ISSN: 1022-0119. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...