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Sample records for vector diffraction theory

  1. Numerical calculation of a converging vector electromagnetic wave diffracted by an aperture by using Borgnis potentials. I. General theory.

    Science.gov (United States)

    Wang, Xueen; Fan, Zhaozhong; Tang, Tiantong

    2006-04-01

    A method is proposed, on the basis of the vector electromagnetic theory, for the numerical calculation of the diffraction of a converging electromagnetic wave by a circular aperture by using Borgnis potentials as auxiliary functions. The diffraction problem of vector electromagnetic fields is simplified greatly by solving the scalar Borgnis potentials. The diffractive field is calculated on the basis of the boundary integral equation, taking into consideration the contribution of the field variables on the diffraction screen surface, which is ignored in the Kirchhoff assumption. An example is given to show the effectiveness and suitability of this method and the distinctiveness of the diffractive fields caused by the vector characteristics of the electromagnetic fields.

  2. Gauge Theories of Vector Particles

    Science.gov (United States)

    Glashow, S. L.; Gell-Mann, M.

    1961-04-24

    The possibility of generalizing the Yang-Mills trick is examined. Thus we seek theories of vector bosons invariant under continuous groups of coordinate-dependent linear transformations. All such theories may be expressed as superpositions of certain "simple" theories; we show that each "simple theory is associated with a simple Lie algebra. We may introduce mass terms for the vector bosons at the price of destroying the gauge-invariance for coordinate-dependent gauge functions. The theories corresponding to three particular simple Lie algebras - those which admit precisely two commuting quantum numbers - are examined in some detail as examples. One of them might play a role in the physics of the strong interactions if there is an underlying super-symmetry, transcending charge independence, that is badly broken. The intermediate vector boson theory of weak interactions is discussed also. The so-called "schizon" model cannot be made to conform to the requirements of partial gauge-invariance.

  3. Exclusive Hard Diffraction at HERA (DVCS and Vector Mesons)

    CERN Document Server

    Marage, P

    2010-01-01

    Recent results obtained at HERA on deeply virtual Compton scattering and exclusive vector meson production are reviewed, with the emphasis on the transition from soft to hard diffraction and on spin dynamics.

  4. Use of rigorous vector coupled-wave theory for designing and tolerancing surface-relief diffractive components for magneto-optical heads

    Science.gov (United States)

    Haggans, Charles W.; Kostuk, Raymond K.

    1991-01-01

    A rigorous coupled wave model is presented, experimentally validated, and used for tolerancing surface relief diffractive elements. Applications of the model in the design and tolerancing of components for magneto optical (M-O) data storage heads are investigated.

  5. Electromagnetic diffraction theory of refractive axicon lenses.

    Science.gov (United States)

    Wang, Yangyundou; Yan, Shenggang; Friberg, Ari T; Kuebel, David; Visser, Taco D

    2017-07-01

    We study the field that is produced by a paraxial refractive axicon lens. The results from geometrical optics, scalar wave optics, and electromagnetic diffraction theory are compared. In particular, the axial intensity, the on-axis effective wavelength, the transverse intensity, and the far-zone field are examined. A rigorous electromagnetic diffraction analysis shows that the state of polarization of the incident beam strongly affects the transverse intensity distribution, but not the intensity distribution in the far zone.

  6. Exclusive central diffractive production of scalar, pseudoscalar and vector mesons

    Directory of Open Access Journals (Sweden)

    Lebiedowicz P.

    2014-01-01

    Full Text Available We discuss exclusive central diffractive production of scalar (ƒ0(980, ƒ0(1370, ƒ0(1500, pseudoscalar (η, η′(958, and vector (ρ0 mesons in proton-proton collisions. The amplitudes are formulated in terms of effective vertices required to respect standard rules of Quantum Field Theory and propagators for the exchanged pomeron and reggeons. Different pomeron-pomeron-meson tensorial (vectorial coupling structures are possible in general. In most cases two lowest orbital angular momentum - spin couplings are necessary to describe experimental differential distributions. For the ƒ0(980 and η production the reggeon-pomeron, pomeron-reggeon, and reggeon-reggeon exchanges are included in addition, which seems to be necessary at relatively low energies. The theoretical results are compared with the WA102 experimental data, in order to determine the model parameters. For the ρ0 production the photon-pomeron and pomeron-photon exchanges are considered. The coupling parameters of tensor pomeron and/or reggeon are fixed from the H1 and ZEUS experimental data of the γp → ρ0 p reaction. We present first predictions of this mechanism for pp → ppπ+π− reaction being studied at COMPASS, RHIC, Tevatron, and LHC. Correlation in azimuthal angle between outgoing protons and distribution in pion rapidities at √s = 7 TeV are presented. We show that high-energy central production of mesons could provide crucial information on the spin structure of the soft pomeron.

  7. Polar POLICRYPS diffractive structures generate cylindrical vector beams

    Energy Technology Data Exchange (ETDEWEB)

    Alj, Domenico; Caputo, Roberto, E-mail: roberto.caputo@fis.unical.it; Umeton, Cesare [Department of Physics and CNR-NANOTEC University of Calabria, I-87036 Rende (CS) (Italy); Paladugu, Sathyanarayana [Soft Matter Lab, Department of Physics, Bilkent University, Ankara 06800 (Turkey); Volpe, Giovanni [Soft Matter Lab, Department of Physics, Bilkent University, Ankara 06800 (Turkey); UNAM-National Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey)

    2015-11-16

    Local shaping of the polarization state of a light beam is appealing for a number of applications. This can be achieved by employing devices containing birefringent materials. In this article, we present one such enables converting a uniformly circularly polarized beam into a cylindrical vector beam (CVB). This device has been fabricated by exploiting the POLICRYPS (POlymer-LIquid CRYstals-Polymer-Slices) photocuring technique. It is a liquid-crystal-based optical diffraction grating featuring polar symmetry of the director alignment. We have characterized the resulting CVB profile and polarization for the cases of left and right circularly polarized incoming beams.

  8. Vector optimization theory, applications, and extensions

    CERN Document Server

    Jahn, Johannes

    2011-01-01

    This new edition of a key monograph has fresh sections on the work of Edgeworth and Pareto in its presentation in a general setting of the fundamentals and important results of vector optimization. It examines background material, applications and theories.

  9. Contribution to diffraction theory; Contribution a la theorie de la diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Chako, N. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-11-01

    In a first part, we have given a general and detailed treatment of the modern theory of diffraction. The rigorous theory is formulated as a boundary value problem of the wave equation or Maxwell equations. However, up to the present time, such a program of treating diffraction by optical systems, even for simple optical instruments, has not been realized due to the complicated character of the boundary conditions. The recent developments show clearly the nature of the approximation of the classical theories originally due to Fresnel and Young, later formulated in a rigorous manner by Kirchhoff and Rubinowicz, respectively and, at the same time the insufficiency of these theories in explaining a number of diffraction phenomena. Furthermore, we have made a study of the limitations of the approximate theories and the recent attempts to improve these. The second part is devoted to a general mathematical treatment of the theory of diffraction of optical systems including aberrations. After a general and specific analysis of geometrical and wave aberrations along classical and modern (Nijboer) lines, we have been able to evaluate the diffraction integrals representing the image field at any point in image space explicitly, when the aberrations are small. Our formulas are the generalisations of all anterior results obtained by previous investigators. Moreover, we have discussed the Zernike-Nijboer theory of aberration and generalised it not only for rotational systems, but also for non-symmetric systems as well, including the case of non circular apertures. The extension to non-circular apertures is done by introducing orthogonal functions or polynomials over such aperture shapes. So far the results are valid for small aberrations, that is to say, where the deformation of the real wave front emerging from the optical system is less than a wave length of light or of the electromagnetic wave from the ideal wave front. If the aberrations are large, then one must employ the

  10. Diffractive S and D-wave vector mesons in deep inelastic scattering

    OpenAIRE

    Ivanov, I. P.; Nikolaev, N.N.

    1999-01-01

    We derive helicity amplitudes for diffractive leptoproduction of the S and D wave states of vector mesons. We predict a dramatically different spin dependence for production of the S and D wave vector mesons. We find very small $R=\\sigma_{L}/\\sigma_{T}$ and abnormally large higher twist effects in production of longitudinally polarized D-wave vector mesons.

  11. Black holes in vector-tensor theories

    Science.gov (United States)

    Heisenberg, Lavinia; Kase, Ryotaro; Minamitsuji, Masato; Tsujikawa, Shinji

    2017-08-01

    We study static and spherically symmetric black hole (BH) solutions in second-order generalized Proca theories with nonminimal vector field derivative couplings to the Ricci scalar, the Einstein tensor, and the double dual Riemann tensor. We find concrete Lagrangians which give rise to exact BH solutions by imposing two conditions of the two identical metric components and the constant norm of the vector field. These exact solutions are described by either Reissner-Nordström (RN), stealth Schwarzschild, or extremal RN solutions with a non-trivial longitudinal mode of the vector field. We then numerically construct BH solutions without imposing these conditions. For cubic and quartic Lagrangians with power-law couplings which encompass vector Galileons as the specific cases, we show the existence of BH solutions with the difference between two non-trivial metric components. The quintic-order power-law couplings do not give rise to non-trivial BH solutions regular throughout the horizon exterior. The sixth-order and intrinsic vector-mode couplings can lead to BH solutions with a secondary hair. For all the solutions, the vector field is regular at least at the future or past horizon. The deviation from General Relativity induced by the Proca hair can be potentially tested by future measurements of gravitational waves in the nonlinear regime of gravity.

  12. Vector wave diffraction pattern of slits masked by polarizing devices

    Indian Academy of Sciences (India)

    Polarization property is important to the optical imaging system. It has recently been understood that the polarization properties of light can be fruitfully used for improving the characteristics of imaging system that includes polarizing devices. The vector wave imagery lends an additional degree of freedom that can be utilized ...

  13. Vector wave diffraction pattern of slits masked by polarizing devices

    Indian Academy of Sciences (India)

    Amplitude and phase step filters were used on the pupil of the optical system to achieve ... of polarization Fourier optics dealing with vector wave imagery and image processing. [8–10]. Recently, Moreno et al have ..... obtained in circular aperture using. Gaussian modulation of the transmission function of a circular aperture.

  14. Theory of time-resolved inelastic x-ray diffraction

    DEFF Research Database (Denmark)

    Lorenz, Ulf; Møller, Klaus Braagaard; Henriksen, Niels Engholm

    2010-01-01

    Starting from a general theory of time-resolved x-ray scattering, we derive a convenient expression for the diffraction signal based on a careful analysis of the relevant inelastic scattering processes. We demonstrate that the resulting inelastic limit applies to a wider variety of experimental...... conditions than similar, previously derived formulas, and it directly allows the application of selection rules when interpreting diffraction signals. Furthermore, we present a simple extension to systems simultaneously illuminated by x rays and a laser beam....

  15. 50 years with J. B. Keller's Geometrical Theory of Diffraction in Denmark - Revisiting the Theory

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Albertsen, N. Chr.; Breinbjerg, Olav

    2013-01-01

    In the introduction, Danish contributions to J. B. Keller's Geometrical Theory of Diffraction are surveyed. The edge diffraction coefficient in the case of scattering by a half-plane with an impedance surface is then analyzed. In short-wavelength scattering theory, the amplitudes of the incident...

  16. Transition operators in electromagnetic-wave diffraction theory - General theory

    Science.gov (United States)

    Hahne, G. E.

    1992-01-01

    A formal theory is developed for the scattering of time-harmonic electromagnetic waves from impenetrable immobile obstacles with given linear, homogeneous, and generally nonlocal boundary conditions of Leontovich (impedance) type for the wave of the obstacle's surface. The theory is modeled on the complete Green's function and the transition (T) operator in time-independent formal scattering theory of nonrelativistic quantum mechanics. An expression for the differential scattering cross section for plane electromagnetic waves is derived in terms of certain matrix elements of the T operator for the obstacle.

  17. Compact stars in vector-tensor-Horndeski theory of gravity

    Energy Technology Data Exchange (ETDEWEB)

    Momeni, Davood; Myrzakulov, Kairat; Myrzakulov, Ratbay [Eurasian National University, Department of General and Theoretical Physics, Eurasian International Center for Theoretical Physics, Astana (Kazakhstan); Faizal, Mir [University of British Columbia-Okanagan, Irving K. Barber School of Arts and Sciences, Kelowna, BC (Canada); University of Lethbridge, Department of Physics and Astronomy, Lethbridge, AB (Canada)

    2017-01-15

    In this paper, we will analyze a theory of modified gravity, in which the field content of general relativity will be increased to include a vector field. We will use the Horndeski formalism to non-minimally couple this vector field to the metric. As we will be using the Horndeski formalism, this theory will not contain Ostrogradsky ghost degree of freedom. We will analyze compact stars using this vector-tensor-Horndeski theory. (orig.)

  18. Support vector machines optimization based theory, algorithms, and extensions

    CERN Document Server

    Deng, Naiyang; Zhang, Chunhua

    2013-01-01

    Support Vector Machines: Optimization Based Theory, Algorithms, and Extensions presents an accessible treatment of the two main components of support vector machines (SVMs)-classification problems and regression problems. The book emphasizes the close connection between optimization theory and SVMs since optimization is one of the pillars on which SVMs are built.The authors share insight on many of their research achievements. They give a precise interpretation of statistical leaning theory for C-support vector classification. They also discuss regularized twi

  19. Phase Retrieval with One or Two Diffraction Patterns by Alternating Projections of the Null Vector

    CERN Document Server

    Chen, Pengwen; Liu, Gi-Ren

    2015-01-01

    Two versions of alternating projection (AP), the parallel alternating projection (PAP) and the serial alternating projection (SAP), are proposed to solve phase retrieval with at most two coded diffraction patterns. The proofs of geometric convergence are given with sharp bounds on the rates of convergence in terms of a spectral gap condition. To compensate for the local nature of convergence, the null vector method is proposed for initialization and proved to produce asymptotically accurate initialization for the Gaussian case. Extensive numerical experiments are performed to show that the null vector method produces more accurate initialization than the spectral vector method and that PAP/SAP converge faster to more accurate solutions than other iterative schemes for non-convex optimization such as the Wirtinger flow. Moreover, SAP converges still faster than PAP. In practice AP and the null vector method together produce globally convergent iterates to the true object.

  20. Extending geometrical optics: A Lagrangian theory for vector waves

    Science.gov (United States)

    Ruiz, D. E.; Dodin, I. Y.

    2017-05-01

    Even when neglecting diffraction effects, the well-known equations of geometrical optics (GO) are not entirely accurate. Traditional GO treats wave rays as classical particles, which are completely described by their coordinates and momenta, but vector-wave rays have another degree of freedom, namely, their polarization. The polarization degree of freedom manifests itself as an effective (classical) "wave spin" that can be assigned to rays and can affect the wave dynamics accordingly. A well-known manifestation of polarization dynamics is mode conversion, which is the linear exchange of quanta between different wave modes and can be interpreted as a rotation of the wave spin. Another, less-known polarization effect is the polarization-driven bending of ray trajectories. This work presents an extension and reformulation of GO as a first-principle Lagrangian theory, whose effective Hamiltonian governs the aforementioned polarization phenomena simultaneously. As an example, the theory is applied to describe the polarization-driven divergence of right-hand and left-hand circularly polarized electromagnetic waves in weakly magnetized plasma.

  1. Design of structurally colored surfaces based on scalar diffraction theory

    DEFF Research Database (Denmark)

    Johansen, Villads Egede; Andkjær, Jacob Anders; Sigmund, Ole

    2014-01-01

    In this paper we investigate the possibility of controlling the color and appearance of surfaces simply by modifying the height profile of the surface on a nanoscale level. The applications for such methods are numerous: new design possibilities for high-end products, color engraving on any highly...... reflective surface, paint-free text and coloration, UV-resistant coloring, etc. In this initial study, the main focus is on finding a systematic way to obtain these results. For now the simulation and optimization is based on a simple scalar diffraction theory model. From the results, several design issues...

  2. Uniform theory of diffraction (UTD)-based solution for sound diffraction caused by an array of obstacles.

    Science.gov (United States)

    Rodríguez, José-Víctor; Pascual-García, Juan; Martínez-Inglés, María-Teresa; Molina-Garcia-Pardo, Jose-Maria; Juan-Llácer, Leandro

    2017-08-01

    A formulation based on the uniform theory of diffraction (UTD) for the analysis of the multiple-diffraction of a spherical sound wave caused by a series of wedges or knife-edges is hereby presented. The receiver location has to be considered at the same height as the preceding obstacles and at the same inter-obstacle distance from the last wedge. The solution, which is based on a UTD-physical optics formulation for radio-wave multiple-diffraction and has been validated through comparison with a geometrical theory of diffraction acoustic model, is computationally more efficient than other existing methods thanks to the fact that only single diffractions are involved in the calculations (high-order diffraction terms are not considered in the diffraction coefficients), thus allowing for the consideration of a great number of obstacles. In such a way, the proposed solution overcomes the limitations of previous works when multiple acoustic diffraction caused by an array of elements of equal height is to be analyzed. Therefore, the results can be applied in the study of sound propagation in scenarios where multiple-diffraction over a series of edges of equal height and periodical spacing has to be considered, such as the typical audience seating of a concert hall.

  3. Diffraction theory for azimuthally structured Fresnel zone plate.

    Science.gov (United States)

    Vierke, Thordis; Jahns, Jürgen

    2014-02-01

    A conventional Fresnel zone plate (FZP) consists of concentric rings with an alternating binary transmission of zero and one. In an azimuthally structured Fresnel zone plate (aFZP), the light transmission of the transparent zones is modulated in the azimuthal direction, too. The resulting structure is of interest for extreme ultraviolet and x-ray imaging, in particular, because of its improved mechanical stability as compared to the simple ring structure of an FZP. Here, we present an analysis of the optical performance of the aFZP based on scalar diffraction theory and show numerical results for the light distribution in the focal plane. These will be complemented by calculations of the optical transfer function.

  4. Pattern vectors from algebraic graph theory.

    Science.gov (United States)

    Wilson, Richard C; Hancock, Edwin R; Luo, Bin

    2005-07-01

    Graph structures have proven computationally cumbersome for pattern analysis. The reason for this is that, before graphs can be converted to pattern vectors, correspondences must be established between the nodes of structures which are potentially of different size. To overcome this problem, in this paper, we turn to the spectral decomposition of the Laplacian matrix. We show how the elements of the spectral matrix for the Laplacian can be used to construct symmetric polynomials that are permutation invariants. The coefficients of these polynomials can be used as graph features which can be encoded in a vectorial manner. We extend this representation to graphs in which there are unary attributes on the nodes and binary attributes on the edges by using the spectral decomposition of a Hermitian property matrix that can be viewed as a complex analogue of the Laplacian. To embed the graphs in a pattern space, we explore whether the vectors of invariants can be embedded in a low-dimensional space using a number of alternative strategies, including principal components analysis (PCA), multidimensional scaling (MDS), and locality preserving projection (LPP). Experimentally, we demonstrate that the embeddings result in well-defined graph clusters. Our experiments with the spectral representation involve both synthetic and real-world data. The experiments with synthetic data demonstrate that the distances between spectral feature vectors can be used to discriminate between graphs on the basis of their structure. The real-world experiments show that the method can be used to locate clusters of graphs.

  5. Theory of net analyte signal vectors in inverse regression

    DEFF Research Database (Denmark)

    Bro, R.; Andersen, Charlotte Møller

    2003-01-01

    The. net analyte signal and the net analyte signal vector are useful measures in building and optimizing multivariate calibration models. In this paper a theory for their use in inverse regression is developed. The theory of net analyte signal was originally derived from classical least squares...

  6. Near-field diffraction from amplitude diffraction gratings: theory, simulation and results

    Science.gov (United States)

    Abedin, Kazi Monowar; Rahman, S. M. Mujibur

    2017-08-01

    We describe a computer simulation method by which the complete near-field diffract pattern of an amplitude diffraction grating can be generated. The technique uses the method of iterative Fresnel integrals to calculate and generate the diffraction images. Theoretical background as well as the techniques to perform the simulation is described. The program is written in MATLAB, and can be implemented in any ordinary PC. Examples of simulated diffraction images are presented and discussed. The generated images in the far-field where they reduce to Fraunhofer diffraction pattern are also presented for a realistic grating, and compared with the results predicted by the grating equation, which is applicable in the far-field. The method can be used as a tool to teach the complex phenomenon of diffraction in classrooms.

  7. Computer modeling of electromagnetic problems using the geometrical theory of diffraction

    Science.gov (United States)

    Burnside, W. D.

    1976-01-01

    Some applications of the geometrical theory of diffraction (GTD), a high frequency ray optical solution to electromagnetic problems, are presented. GTD extends geometric optics, which does not take into account the diffractions occurring at edges, vertices, and various other discontinuities. Diffraction solutions, analysis of basic structures, construction of more complex structures, and coupling using GTD are discussed.

  8. The method of the generalised eikonal new approaches in the diffraction theory

    CERN Document Server

    Vesnik, Michael V

    2015-01-01

    The diffraction theory describes scattering mechanism for waves of various physical nature, scattered on objects of different shapes and composed of different materials. Using the diffraction theory, one can study a number of important effects connected with wave propagation, and create objects with given properties.

  9. Stealth configurations in vector-tensor theories of gravity

    Science.gov (United States)

    Chagoya, Javier; Tasinato, Gianmassimo

    2018-01-01

    Studying the physics of compact objects in modified theories of gravity is important for understanding how future observations can test alternatives to General Relativity. We consider a subset of vector-tensor Galileon theories of gravity characterized by new symmetries, which can prevent the propagation of the vector longitudinal polarization, even in absence of Abelian gauge invariance. We investigate new spherically symmetric and slowly rotating solutions for these systems, including an arbitrary matter Lagrangian. We show that, under certain conditions, there always exist stealth configurations whose geometry coincides with solutions of Einstein gravity coupled with the additional matter. Such solutions have a non-trivial profile for the vector field, characterized by independent integration constants, which extends to asymptotic infinity. We interpret our findings in terms of the symmetries and features of the original vector-tensor action, and on the number of degrees of freedom that it propagates. These results are important to eventually describe gravitationally bound configurations in modified theories of gravity, such as black holes and neutron stars, including realistic matter fields forming or surrounding the object.

  10. Laue diffraction lenses for astrophysics: From theory to experiments

    OpenAIRE

    Halloin, H.

    2006-01-01

    Based on the laws of X-ray diffraction in crystals, Laue lenses offer a promising way to achieve the sensitivity and angular resolution leap required for the next generation of hard X-ray and gamma-ray telescopes. The present paper describes the instrumental responses of Laue diffraction lenses designed for nuclear astrophysics. Different possible geometries are discussed, as well as the corresponding spectral and imaging capabilities. These theoretical predictions are then compared with Mont...

  11. Cosmologies in Horndeski's second-order vector-tensor theory

    CERN Document Server

    Barrow, John D; Yamamoto, Kei

    2012-01-01

    Horndeski derived a most general vector-tensor theory in which the vector field respects the gauge symmetry and the resulting dynamical equations are of second order. The action contains only one free parameter, $\\lambda$, that determines the strength of the non-minimal coupling between the gauge field and gravity. We investigate the cosmological consequences of this action and discuss observational constraints. For $\\lambda<0$ we identify singularities where the deceleration parameter diverges within a finite proper time. This effectively rules out any sensible cosmological application of the theory for a negative non-minimal coupling. We also find a range of parameter that gives a viable cosmology and study the phenomenology for this case. Observational constraints on the value of the coupling are rather weak since the interaction is higher-order in space-time curvature.

  12. Application Of Geometrical Theory Of Diffraction (GTD) Techniques to GPS Signal Propagation Through Ionospheric Density Irregularities.

    Science.gov (United States)

    Vadepu, S. K.; Spencer, E. A.; Gollapalli, R.

    2016-12-01

    Shorter scale electron density irregularities in the ionosphere necessitates the consideration of diffractive in addition to refractive effects on the propagation of radio wave signals. For the GPS L1 frequency of 1575.42 MHz, the diffractive effects become appreciable for irregularities on the order of 1- 5 meters (around 5 to 25 wavelengths). Such irregularities are suggested during times of strong ionospheric scintillation. Although the diffractive effects are much weaker than the refraction which can be calculated using the geometrical optics approximation, we are interested to examine how the geometrical theory of diffraction (GTD) can be used to obtain higher order corrections to the propagated fields. Here we calculate the diffraction coefficients for an electromagnetic plane wave propagating through a small ionospheric patch, approximated as a circular convex lens. We use a particular form of the GTD, called the Uniform Theory Of Diffraction (UTD) (Pathak and Kouyoumjian, Proc. IEEE, vol. 62, no. 11, pp. 1448-1461) to extract diffraction coefficients for a plasma wedge in 2 dimensions, and then introduce a spatial attenuation factor for a curved edge as a modification to the diffracted rays as they propagate away from the simulated curved wedge. We estimate the diffraction contribution as a function of patch size, and evaluate the contribution of the diffracted component of the field to both the amplitude and phase scintillation of GPS L1 signals.

  13. Effective field theory and unitarity in vector boson scattering

    Energy Technology Data Exchange (ETDEWEB)

    Sekulla, Marco [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany); Kilian, Wolfgang [Siegen Univ. (Germany); Ohl, Thorsten [Wuerzburg Univ. (Germany); Reuter, Juergen [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group

    2016-10-15

    Weak vector boson scattering at high energies will be one of the key measurements in current and upcoming LHC runs. It is most sensitive to any new physics associated with electroweak symmetry breaking. However, a conventional EFT analysis will fail at high energies. To address this problem, we present a parameter-free prescription valid for arbitrary perturbative and non-perturbative models: the T-matrix unitarization. We describe its implementation as an asymptotically consistent reference model matched to the low-energy effective theory. We show examples of typical observables of vector-boson scattering at the LHC in our unitarized framework. For many strongly-coupled models like composite Higgs models, dimension-8 operators might be actually the leading operators. In addition to those longitudinal and transversal dimension eight EFT operators, the effects of generic tensor and scalar resonances within simplified models are considered.

  14. Random Vector and Matrix Theories: A Renormalization Group Approach

    Science.gov (United States)

    Zinn-Justin, Jean

    2014-09-01

    Random matrices in the large N expansion and the so-called double scaling limit can be used as toy models for quantum gravity: 2D quantum gravity coupled to conformal matter. This has generated a tremendous expansion of random matrix theory, tackled with increasingly sophisticated mathematical methods and number of matrix models have been solved exactly. However, the somewhat paradoxical situation is that either models can be solved exactly or little can be said. Since the solved models display critical points and universal properties, it is tempting to use renormalization group ideas to determine universal properties, without solving models explicitly. Initiated by Br\\'ezin and Zinn-Justin, the approach has led to encouraging results, first for matrix integrals and then quantum mechanics with matrices, but has not yet become a universal tool as initially hoped. In particular, general quantum field theories with matrix fields require more detailed investigations. To better understand some of the encountered difficulties, we first apply analogous ideas to the simpler O(N) symmetric vector models, models that can be solved quite generally in the large N limit. Unlike other attempts, our method is a close extension of Br\\'ezin and Zinn-Justin. Discussing vector and matrix models with similar approximation scheme, we notice that in all cases (vector and matrix integrals, vector and matrix path integrals in the local approximation), at leading order, non-trivial fixed points satisfy the same universal algebraic equation, and this is the main result of this work. However, its precise meaning and role have still to be better understood.

  15. Cooperative Adsorption by Porous Frameworks: Diffraction Experiment and Phenomenological Theory.

    Science.gov (United States)

    Dovgaliuk, Iurii; Nouar, Farid; Serre, Christian; Filinchuk, Yaroslav; Chernyshov, Dmitry

    2017-09-04

    Materials science of metal open frameworks is a state-of-the-art field for numerous applications, such as gas storage, sensors, and medicine. Two nanoporous frameworks, γ-Mg(BH4 )2 and MIL-91(Ti), with different levels of structural flexibility, were examined with in situ X-ray diffraction guest adsorption-desorption experiments. Both frameworks exhibit a cooperative guest adsorption correlated with a lattice deformation. This cooperativity originates from the long-range interactions between guest molecules, mediated by elastic response of the host porous structure. The observed experimental scenarios are rationalized with a mean field Gorsky-Bragg-Williams (GBW) approach for the lattice-gas Ising model. The adjusted GBW model, in combination with in situ synchrotron powder diffraction, demonstrates an efficient experimental and phenomenological approach to characterize thermodynamics of the adsorption in MOFs not only for the total uptake but also for every specific guest site. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Diffractive interface theory: nonlocal susceptibility approach to the optics of metasurfaces.

    Science.gov (United States)

    Roberts, Christopher M; Inampudi, Sandeep; Podolskiy, Viktor A

    2015-02-09

    We present a formalism for understanding the electromagnetism of metasurfaces, optically thin composite films with engineered diffraction. The technique, diffractive interface theory (DIT), takes explicit advantage of the small optical thickness of a metasurface, eliminating the need for solving for light propagation inside the film and providing a direct link between the spatial profile of a metasurface and its diffractive properties. Predictions of DIT are compared with full-wave numerical solutions of Maxwell's equations, demonstrating DIT's validity and computational advantages for optically thin structures. Applications of the DIT range from understanding of fundamentals of light-matter interaction in metasurfaces to efficient analysis of generalized refraction to metasurface optimization.

  17. Diffraction theory of high numerical aperture subwavelength circular binary phase Fresnel zone plate.

    Science.gov (United States)

    Zhang, Yaoju; An, Hongchang; Zhang, Dong; Cui, Guihua; Ruan, Xiukai

    2014-11-03

    An analytical model of vector formalism is proposed to investigate the diffraction of high numerical aperture subwavelength circular binary phase Fresnel zone plate (FZP). In the proposed model, the scattering on the FZP's surface, reflection and refraction within groove zones are considered and diffraction fields are calculated using the vector Rayleigh-Sommerfeld integral. The numerical results obtained by the proposed phase thick FZP (TFZP) model show a good agreement with those obtained by the finite-difference time-domain (FDTD) method within the effective extent of etch depth. The optimal etch depths predicted by both methods are approximately equal. The analytical TFZP model is very useful for designing a phase and hybrid amplitude-phase FZP with high-NA and short focal length.

  18. Application of the geometrical theory of diffraction to Cassegrain subreflectors with laterally defocused feeds

    DEFF Research Database (Denmark)

    Sørensen, O.; Rusch, W.

    1975-01-01

    current placed along the edge of the subreflector. The theoretical results are compared to measured amplitude and phase data. In order to improve the agreement, the blocking effects of the feed horn have been accounted for using the geometrical theory of diffraction. The calculated subreflector fields......The geometrical theory of diffraction (GTD) as formulated by R. G. Kouyoumjian has been applied to predict the radiation characteristics of hyperboloidal subreflectors with laterally defocused feeds. In caustic or multicaustic directions the scattered fields are determined using an equivalent ring...

  19. Generalized vector wave theory for ultrahigh resolution confocal optical microscopy.

    Science.gov (United States)

    Yang, Ken; Xie, Xiangsheng; Zhou, Jianying

    2017-01-01

    Polarization modulation of a tightly focused beam in a confocal imaging scheme is considered for incident and collected light fields. Rigorous vector wave theory of a confocal optical microscopy is developed, which provides clear physical pictures without the requirement for fragmentary calculations. Multiple spatial modulations on polarization, phase, or amplitude of the illuminating and the detected beams can be mathematically described by a uniform expression. Linear and nonlinear excitation schemes are derived with tailored excitation and detection fields within this generalized theory, whose results show that the ultimate resolution achieved with the linear excitation can reach one-fifth of the excitation wavelength (or λ/5), while the nonlinear excitation scheme gives rise to a resolution better than λ/12 for two-photon fluorescence excitation and λ/20 for three-photon fluorescence excitation. Hence the resolution of optical microscopy with a near-infrared excitation can routinely reach sub-60 nm. In addition, simulations for confocal laser scanning microscopy are carried out with the linear excitation scheme and the fluorescent one, respectively.

  20. A system model for ultrasonic NDT based on the Physical Theory of Diffraction (PTD).

    Science.gov (United States)

    Darmon, M; Dorval, V; Kamta Djakou, A; Fradkin, L; Chatillon, S

    2016-01-01

    Simulation of ultrasonic Non Destructive Testing (NDT) is helpful for evaluating performances of inspection techniques and requires the modelling of waves scattered by defects. Two classical flaw scattering models have been previously usually employed and evaluated to deal with inspection of planar defects, the Kirchhoff approximation (KA) for simulating reflection and the Geometrical Theory of Diffraction (GTD) for simulating diffraction. Combining them so as to retain advantages of both, the Physical Theory of Diffraction (PTD) initially developed in electromagnetism has been recently extended to elastodynamics. In this paper a PTD-based system model is proposed for simulating the ultrasonic response of crack-like defects. It is also extended to provide good description of regions surrounding critical rays where the shear diffracted waves and head waves interfere. Both numerical and experimental validation of the PTD model is carried out in various practical NDT configurations, such as pulse echo and Time of Flight Diffraction (TOFD), involving both crack tip and corner echoes. Numerical validation involves comparison of this model with KA and GTD as well as the Finite-Element Method (FEM). Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Application of a particular class of integrals in the theory of diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Kamishi, Burim, E-mail: burim.kamishi@uni-pr.edu; Bejtullahu, Rasim [Faculty of Natural Sciences and Mathematics, University of Prishtina, Prishtina, Kosovo (Country Unknown); Sykja, Halil [Faculty of Natural Sciences, University of Tirana, Tirana (Albania)

    2016-03-25

    A particular class of integrals appearing in the problems of diffraction is treated in this paper. For the analysis of the classical sources or lasers, Kirchhoff’s integral can be used only for apertures of a determined shape. So far, the problems are solved and analyzed completely, whenever the geomtry of apertures creates the possibility of using Kirchhoff’s integral, namely for the so-called geometry of rectangular apertures. Other apertures exist for which Kirchhoff’s integral cannot be applied, because of difficulties of mathematical character. In this group of apertures belong all the apertures which are bounded with an inclined line, such as those with triangular form. In this paper, the application of a particular class of integrals is shown to give satisfying results in two problems of diffraction theory: double-diffraction phenomena consisting on separating the interferential-diffractional field from the diffractional field, and the case of near-zone of diffraction in the triangular aperture.

  2. Knowledge formalization for vector data matching using belief theory

    Directory of Open Access Journals (Sweden)

    Ana-Maria Olteanu-Raimond

    2015-06-01

    Full Text Available Nowadays geographic vector data is produced both by public and private institutions using well defined specifications or crowdsourcing via Web 2.0 mapping portals. As a result, multiple representations of the same real world objects exist, without any links between these different representations. This becomes an issue when integration, updates, or multi-level analysis needs to be performed, as well as for data quality assessment. In this paper a multi-criteria data matching approach allowing the automatic definition of links between identical features is proposed. The originality of the approach is that the process is guided by an explicit representation and fusion of knowledge from various sources. Moreover the imperfection (imprecision, uncertainty, and incompleteness is explicitly modeled in the process. Belief theory is used to represent and fuse knowledge from different sources, to model imperfection, and make a decision. Experiments are reported on real data coming from different producers, having different scales and either representing relief (isolated points or road networks (linear data.

  3. The biconical antenna and its analysis by the geometrical theory of diffraction

    Science.gov (United States)

    Cashman, J. D.; Bolomey, J. Ch.

    1981-06-01

    The geometrical theory of diffraction is applied to the calculation of the far-field emitted radiation patterns of biconical antennas with dimensions much greater than one wavelength, which are representative of point-contact structures. The far-field patterns are calculated directly by the superposition of the fields associated with the various direct and diffracted rays emitted by the antenna for the cases of biconical antennas mounted on infinite cylinders and with spherical extremities, and the results are shown to be in agreement with those obtained by other approximate methods. Consideration is then given to the case of antennas mounted on finite cylinders as a function of antenna dimensions, and limits to the application of the technique in the calculation of fields along the antenna axis and doubly diffracted rays are considered.

  4. Statistical Theory of the Vector Random Decrement Technique

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Brincker, Rune; Ibrahim, S. R.

    1999-01-01

    The Vector Random Decrement technique has previously been introduced as an effcient method to transform ambient responses of linear structures into Vector Random Decrement functions which are equivalent to free decays of the current structure. The modal parameters can be extracted from the free...

  5. Special function related to the concave-convex boundary problem of the diffraction theory

    CERN Document Server

    Kazakov, A Y

    2003-01-01

    The concave-convex boundary problem of the diffraction theory is studied. It corresponds to the scattering of a whispering gallery mode on the point of inflection of the boundary. A new special function related to this boundary problem is introduced and its particular properties are discussed. This special function is defined as a contour integral on the complex plane and its behaviour in different domains of parameters is considered.

  6. Uniform physical theory of diffraction equivalent edge currents for implementation in general computer codes

    DEFF Research Database (Denmark)

    Johansen, Peter Meincke

    1996-01-01

    New uniform closed-form expressions for physical theory of diffraction equivalent edge currents are derived for truncated incremental wedge strips. In contrast to previously reported expressions, the new expressions are well-behaved for all directions of incidence and observation and take a finite...... value for zero strip length. Consequently, the new equivalent edge currents are, to the knowledge of the author, the first that are well-suited for implementation in general computer codes...

  7. Transition operators in electromagnetic-wave diffraction theory. II - Applications to optics

    Science.gov (United States)

    Hahne, G. E.

    1993-01-01

    The theory developed by Hahne (1992) for the diffraction of time-harmonic electromagnetic waves from fixed obstacles is briefly summarized and extended. Applications of the theory are considered which comprise, first, a spherical harmonic expansion of the so-called radiation impedance operator in the theory, for a spherical surface, and second, a reconsideration of familiar short-wavelength approximation from the new standpoint, including a derivation of the so-called physical optics method on the basis of quasi-planar approximation to the radiation impedance operator, augmented by the method of stationary phase. The latter includes a rederivation of the geometrical optics approximation for the complete Green's function for the electromagnetic field in the presence of a smooth- and a convex-surfaced perfectly electrically conductive obstacle.

  8. Algebra of Complex Vectors and Applications in Electromagnetic Theory and Quantum Mechanics

    Directory of Open Access Journals (Sweden)

    Kundeti Muralidhar

    2015-08-01

    Full Text Available A complex vector is a sum of a vector and a bivector and forms a natural extension of a vector. The complex vectors have certain special geometric properties and considered as algebraic entities. These represent rotations along with specified orientation and direction in space. It has been shown that the association of complex vector with its conjugate generates complex vector space and the corresponding basis elements defined from the complex vector and its conjugate form a closed complex four dimensional linear space. The complexification process in complex vector space allows the generation of higher n-dimensional geometric algebra from (n — 1-dimensional algebra by considering the unit pseudoscalar identification with square root of minus one. The spacetime algebra can be generated from the geometric algebra by considering a vector equal to square root of plus one. The applications of complex vector algebra are discussed mainly in the electromagnetic theory and in the dynamics of an elementary particle with extended structure. Complex vector formalism simplifies the expressions and elucidates geometrical understanding of the basic concepts. The analysis shows that the existence of spin transforms a classical oscillator into a quantum oscillator. In conclusion the classical mechanics combined with zeropoint field leads to quantum mechanics.

  9. Image Classification with the Fisher Vector: Theory and Practice

    NARCIS (Netherlands)

    Sánchez, J.; Perronnin, F.; Mensink, T.; Verbeek, J.

    2013-01-01

    A standard approach to describe an image for classification and retrieval purposes is to extract a set of local patch descriptors, encode them into a high dimensional vector and pool them into an image-level signature. The most common patch encoding strategy consists in quantizing the local

  10. Vectors

    DEFF Research Database (Denmark)

    Boeriis, Morten; van Leeuwen, Theo

    2017-01-01

    This article revisits the concept of vectors, which, in Kress and van Leeuwen’s Reading Images (2006), plays a crucial role in distinguishing between ‘narrative’, action-oriented processes and ‘conceptual’, state-oriented processes. The use of this concept in image analysis has usually focused...... on the most salient vectors, and this works well, but many images contain a plethora of vectors, which makes their structure quite different from the linguistic transitivity structures with which Kress and van Leeuwen have compared ‘narrative’ images. It can also be asked whether facial expression vectors...... should be taken into account in discussing ‘reactions’, which Kress and van Leeuwen link only to eyeline vectors. Finally, the question can be raised as to whether actions are always realized by vectors. Drawing on a re-reading of Rudolf Arnheim’s account of vectors, these issues are outlined...

  11. Lattice thermal expansion and anisotropic displacements in -sulfur from diffraction experiments and first-principles theory.

    Science.gov (United States)

    George, Janine; Deringer, Volker L; Wang, Ai; Müller, Paul; Englert, Ulli; Dronskowski, Richard

    2016-12-21

    Thermal properties of solid-state materials are a fundamental topic of study with important practical implications. For example, anisotropic displacement parameters (ADPs) are routinely used in physics, chemistry, and crystallography to quantify the thermal motion of atoms in crystals. ADPs are commonly derived from diffraction experiments, but recent developments have also enabled their first-principles prediction using periodic density-functional theory (DFT). Here, we combine experiments and dispersion-corrected DFT to quantify lattice thermal expansion and ADPs in crystalline α-sulfur (S8), a prototypical elemental solid that is controlled by the interplay of covalent and van der Waals interactions. We begin by reporting on single-crystal and powder X-ray diffraction measurements that provide new and improved reference data from 10 K up to room temperature. We then use several popular dispersion-corrected DFT methods to predict vibrational and thermal properties of α-sulfur, including the anisotropic lattice thermal expansion. Hereafter, ADPs are derived in the commonly used harmonic approximation (in the computed zero-Kelvin structure) and also in the quasi-harmonic approximation (QHA) which takes the predicted lattice thermal expansion into account. At the PPBE+D3(BJ) level, the QHA leads to excellent agreement with experiments. Finally, more general implications of this study for theory and experiment are discussed.

  12. Quantitative simulation of ultrasonic time of flight diffraction technique in 2D geometries using Huygens-Fresnel diffraction model: theory and experimental comparison.

    Science.gov (United States)

    Kolkoori, Sanjeevareddy; Chitti Venkata, Krishnamurthy; Balasubramaniam, Krishnan

    2015-01-01

    This article presents an analytical approach for simulation of ultrasonic diffracted wave signals from cracks in two-dimensional geometries based on a novel Huygens-Fresnel Diffraction Model (HFDM). The model employs the frequency domain far-field displacement expressions derived by Miller and Pursey in 2D for a line source located on the free surface boundary of a semi-infinite elastic medium. At each frequency in the bandwidth of a pulsed excitation, the complex diffracted field is obtained by summation of displacements due to the unblocked virtual sources located in the section containing a vertical crack. The time-domain diffracted wave signal amplitudes in a general isotropic solid are obtained by standard Fast Fourier Transform (FFT) procedures. The wedge based finite aperture transducer refracted beam profiles were modelled by treating the finite dimension transducer as an array of line sources. The proposed model is able to evaluate back-wall signal amplitude and lateral wave signal amplitude, quantitatively. The model predicted range-dependent diffracted amplitudes from the edge of a bottom surface-breaking crack in the isotropic steel specimen were compared with Geometrical Theory of Diffraction (GTD) results. The good agreement confirms the validity of the HFDM method. The simulated ultrasonic time-of-flight diffraction (TOFD) A-scan signals for surface-breaking crack lengths 2 mm and 4 mm in a 10 mm thick aluminium specimen were compared quantitatively with the experimental results. Finally, important applications of HFDM method to the ultrasonic quantitative non-destructive evaluation are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. A new and self-contained presentation of the theory of boundary operators for slit diffraction and their logarithmic approximations

    Energy Technology Data Exchange (ETDEWEB)

    Gorenflo, Norbert [Beuth Hochschule fuer Technik Berlin (Germany). Fachbereich II; Kunik, Matthias [Magdeburg Univ. (Germany). Inst. fuer Analysis und Numerik

    2009-07-01

    We present a new and self-contained theory for mapping properties of the boundary operators for slit diffraction occurring in Sommerfeld's diffraction theory, covering two different cases of the polarisation of the light. This theory is entirely developed in the context of the boundary operators with a Hankel kernel and not based on the corresponding mixed boundary value problem for the Helmholtz equation. For a logarithmic approximation of the Hankel kernel we also study the corresponding mapping properties and derive explicit solutions together with certain regularity results. (orig.)

  14. Suppression of matter couplings with a vector field in generalized Proca theories

    Science.gov (United States)

    Nakamura, Shintaro; Kase, Ryotaro; Tsujikawa, Shinji

    2017-10-01

    In the context of generalized Proca theories, we derive the profile of a vector field Aμ whose squared AμAμ is coupled to the trace T of matter on a static and spherically symmetric background. The cubic Galileon self-interaction leads to the suppression of a longitudinal vector component due to the operation of the Vainshtein mechanism. For quartic and sixth-order derivative interactions, the solutions consistent with those in the continuous limit of small derivative couplings correspond to the branch with the vanishing longitudinal mode. We compute the corrections to gravitational potentials outside a compact body induced by the vector field in the presence of cubic, quartic, and sixth-order derivative couplings, and show that the models can be consistent with local gravity constraints under mild bounds on the temporal vector component. The quintic vector Galileon does not allow regular solutions of the longitudinal mode for a rapidly decreasing matter density outside the body.

  15. Cosmological Solutions of Tensor–Vector Theories of Gravity by ...

    Indian Academy of Sciences (India)

    to the inflation theory in order to solve some puzzles of the Big-Bang cosmological models (Albrecht & Magueijo .... Let us confine ourselves to the case of a spatially flat, homogeneous and isotropic. FRW universe with ... Let us now investigate the explicit forms of the equations for these two cases separately. 2.1 Time-like ...

  16. Fermion frontiers in vector lattice gauge theories: Proceedings. Volume 8

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-11-01

    The inclusion of fermions into simulations of lattice gauge theories is very difficult both theoretically and numerically. With the presence of Teraflops-scale computers for lattice gauge theory, the authors wanted a forum to discuss new approaches to lattice fermions. The workshop concentrated on approaches which are ripe for study on such large machines. Although lattice chiral fermions are vitally important to understand, there is not technique at hand which is viable on these Teraflops-scale machines for real-world problems. The discussion was therefore focused on recent developments and future prospects for QCD-like theories. For the well-known fermion formulations, the Aoki phase in Wilson fermions, novelties of U{sub A}(1) symmetry and the {eta}{prime} for staggered fermions and new approaches for simulating the determinant for Wilson fermions were discussed. The newer domain-wall fermion formulation was reviewed, with numerical results given by many speakers. The fermion proposal of Friedberg, Lee and Pang was introduced. They also were able to compare and contrast the dependence of QCD and QCD-like SUSY theories on the number of quark flavors. These proceedings consist of several transparencies and a summary page from each speaker. This should serve to outline the major points made in each talk.

  17. Biophysical modeling of forward scattering from bacterial colonies using scalar diffraction theory

    Science.gov (United States)

    Bae, Euiwon; Banada, Padmapriya P.; Huff, Karleigh; Bhunia, Arun K.; Robinson, J. Paul; Hirleman, E. Daniel

    2007-06-01

    A model for forward scattering from bacterial colonies is presented. The colonies of interest consist of approximately 1012-1013 individual bacteria densely packed in a configuration several millimeters in diameter and approximately 0.1-0.2 mm in thickness. The model is based on scalar diffraction theory and accounts for amplitude and phase modulation created by three macroscopic properties of the colonies: phase modulation due to the surface topography, phase modulation due to the radial structure observed from some strains and species, and diffraction from the outline of the colony. Phase contrast and confocal microscopy were performed to provide quantitative information on the shape and internal structure of the colonies. The computed results showed excellent agreement with the experimental scattering data for three different Listeria species: Listeria innocua, Listeria ivanovii, and Listeria monocytogenes. The results provide a physical explanation for the unique and distinctive scattering signatures produced by colonies of closely related Listeria species and support the efficacy of forward scattering for rapid detection and classification of pathogens without tagging.

  18. Mechanism of elastic and inelastic proton scattering on a {sup 15}C nucleus in diffraction theory

    Energy Technology Data Exchange (ETDEWEB)

    Ibraeva, E. T., E-mail: ibr@inp.kz [National Nuclear Center of the Republic of Kazakhstan, Institute of Nuclear Physics (Kazakhstan); Zhusupov, M. A. [Al-Farabi Kazakh National University (Kazakhstan); Imambekov, O. [National Nuclear Center of the Republic of Kazakhstan, Institute of Nuclear Physics (Kazakhstan)

    2012-11-15

    The amplitudes for elastic and inelastic proton scattering on the neutron-rich nucleus {sup 15}C (to its J{sup {pi}} = 5/2{sup +} level in the latter case) in inverse kinematics were calculated within Glauber diffraction theory. First- and second-order terms were taken into account in the multiple-scattering operator. The {sup 15}C wave function in the multiparticle shell model was used. This made it possible to calculate not only respective differential cross sections but also the contribution of proton scattering on nucleons occurring in different shells. The differential cross sections for elastic and inelastic scattering were calculated at the energies of 0.2, 0.6, and 1 GeV per nucleon.

  19. Uniform physical theory of diffraction equivalent edge currents for truncated wedge strips

    DEFF Research Database (Denmark)

    Johansen, Peter Meincke

    1996-01-01

    New uniform closed-form expressions for physical theory of diffraction equivalent edge currents are derived for truncated incremental wedge strips. In contrast to previously reported expressions, the new expressions are well behaved for all directions of incidence and observation and take a finite...... value for zero strip length. This means that the expressions are well suited for implementation in general computer codes. The new expressions are expressed as the difference between two terms. The first term is obtained by integrating the exact fringe wave current on a wedge along an untruncated...... incremental strip extending from the leading edge of the structure under consideration. The second term is calculated from an integration of the asymptotic fringe wave (FW) current along another untruncated incremental strip extending from the trailing edge of the structure. The new expressions are tested...

  20. Vector theory of gravity: Universe without black holes and solution of dark energy problem

    Science.gov (United States)

    Svidzinsky, Anatoly A.

    2017-12-01

    We propose an alternative theory of gravity which assumes that background geometry of the Universe is fixed four dimensional Euclidean space and gravity is a vector field A k in this space which breaks the Euclidean symmetry. Direction of A k gives the time coordinate, while perpendicular directions are spatial coordinates. Vector gravitational field is coupled to matter universally and minimally through the equivalent metric f ik which is a functional of A k . We show that such assumptions yield a unique theory of gravity, it is free of black holes and, to the best of our knowledge, passes all available tests. For cosmology our theory predicts the same evolution of the Universe as general relativity with cosmological constant and zero spatial curvature. However, the present theory provides explanation of the dark energy as energy of longitudinal gravitational field induced by the Universe expansion and yields, with no free parameters, the value of {{{Ω }}}{{Λ }}=2/3≈ 0.67 which is consistent with the recent Planck result {{{Ω }}}{{Λ }}=0.686+/- 0.02. Such close agreement with cosmological data indicates that gravity has a vector, rather than tensor, origin. We demonstrate that gravitational wave signals measured by LIGO are compatible with vector gravity. They are produced by orbital inspiral of massive neutron stars which can exist in the present theory. We also quantize gravitational field and show that quantum vector gravity is equivalent to QED. Vector gravity can be tested by making more accurate measurement of the time delay of radar signal traveling near the Sun; by improving accuracy of the light deflection experiments; or by measuring propagation direction of gravitational waves relative to laser interferometer arms. Resolving the supermassive object at the center of our Galaxy with VLBA could provide another test of gravity and also shed light on the nature of dark matter.

  1. Photonic-Doppler-Velocimetry, Paraxial-Scalar Diffraction Theory and Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Ambrose, W. P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-07-20

    In this report I describe current progress on a paraxial, scalar-field theory suitable for simulating what is measured in Photonic Doppler Velocimetry (PDV) experiments in three dimensions. I have introduced a number of approximations in this work in order to bring the total computation time for one experiment down to around 20 hours. My goals were: to develop an approximate method of calculating the peak frequency in a spectral sideband at an instant of time based on an optical diffraction theory for a moving target, to compare the ‘measured’ velocity to the ‘input’ velocity to gain insights into how and to what precision PDV measures the component of the mass velocity along the optical axis, and to investigate the effects of small amounts of roughness on the measured velocity. This report illustrates the progress I have made in describing how to perform such calculations with a full three dimensional picture including tilted target, tilted mass velocity (not necessarily in the same direction), and small amounts of surface roughness. With the method established for a calculation at one instant of time, measured velocities can be simulated for a sequence of times, similar to the process of sampling velocities in experiments. Improvements in these methods are certainly possible at hugely increased computational cost. I am hopeful that readers appreciate the insights possible at the current level of approximation.

  2. Validation of molecular crystal structures from powder diffraction data with dispersion-corrected density functional theory (DFT-D)

    DEFF Research Database (Denmark)

    van de Streek, Jacco; Neumann, Marcus A

    2014-01-01

    In 2010 we energy-minimized 225 high-quality single-crystal (SX) structures with dispersion-corrected density functional theory (DFT-D) to establish a quantitative benchmark. For the current paper, 215 organic crystal structures determined from X-ray powder diffraction (XRPD) data and published...

  3. Crystal structure of radium sulfate: An X-ray powder diffraction and density functional theory study

    Science.gov (United States)

    Matyskin, Artem V.; Ylmen, Rikard; Lagerkvist, Petra; Ramebäck, Henrik; Ekberg, Christian

    2017-09-01

    Radium-barium sulfate (Ra0.76Ba0.24SO4) powder was examined using X-ray Diffraction (XRD) technique and its crystal structure was optimized using Density Functional Theory (DFT). XRD data show that radium and barium sulfate form a solid solution and that Ra0.76Ba0.24SO4 is orthorhombic and isostructural with pure RaSO4, barite (BaSO4), celestite (SrSO4) and anglesite (PbSO4), crystallizing in the space group Pmna (No. 62). The unit cell parameters of the Ra0.76Ba0.24SO4 crystal have been determined using Rietveld refinement and were extrapolated to unit cell parameters of the pure RaSO4 phase using Vegard's law: a=9.129(8), b=5.538(3), c=7.313(5) Å. DFT geometry optimization was used to derive atomic coordinates and interatomic distances in both Ra0.76Ba0.24SO4 and pure RaSO4. The experimental and DFT geometry optimization results obtained in this work are in good agreement with each other, and furthermore with literature data.

  4. Combining the multilevel fast multipole method with the uniform geometrical theory of diffraction

    Directory of Open Access Journals (Sweden)

    A. Tzoulis

    2005-01-01

    Full Text Available The presence of arbitrarily shaped and electrically large objects in the same environment leads to hybridization of the Method of Moments (MoM with the Uniform Geometrical Theory of Diffraction (UTD. The computation and memory complexity of the MoM solution is improved with the Multilevel Fast Multipole Method (MLFMM. By expanding the k-space integrals in spherical harmonics, further considerable amount of memory can be saved without compromising accuracy and numerical speed. However, until now MoM-UTD hybrid methods are restricted to conventional MoM formulations only with Electric Field Integral Equation (EFIE. In this contribution, a MLFMM-UTD hybridization for Combined Field Integral Equation (CFIE is proposed and applied within a hybrid Finite Element - Boundary Integral (FEBI technique. The MLFMM-UTD hybridization is performed at the translation procedure on the various levels of the MLFMM, using a far-field approximation of the corresponding translation operator. The formulation of this new hybrid technique is presented, as well as numerical results.

  5. Improved theory of noncomplanar diffraction of X-Rays under specular reflection conditions

    CERN Document Server

    Balyan, M K

    2000-01-01

    In two-wave approximation the equations describing the dynamical diffraction of X-ray spatially modulated waves in ideal and deformed crystals in grazing noncomplanar incidence geometry are obtained. The solutions of obtained equations for diffraction of arbitrary spatially modulated incidence wave in ideal half-infinite crystal are found. As a special case of the obtained solutions, the diffraction of incidence spherical wave under small grazing angle is briefly considered.

  6. Possible effect of static surface disorder on diffractive scattering of H2 from Ru(0001): Comparison between theory and experiment.

    Science.gov (United States)

    Kroes, G J; Wijzenbroek, Mark; Manson, J R

    2017-12-28

    Specific features of diffractive scattering of H2 from metal surfaces can serve as fingerprints of the reactivity of the metal towards H2, and in principle theory-experiment comparisons for molecular diffraction can help with the validation of semi-empirical functionals fitted to experiments of sticking of H2 on metals. However, a recent comparison of calculated and Debye-Waller (DW) extrapolated experimental diffraction probabilities, in which the theory was done on the basis of a potential energy surface (PES) accurately describing sticking to Ru(0001), showed substantial discrepancies, with theoretical and experimental probabilities differing by factors of 2 and 3. We demonstrate that assuming a particular amount of random static disorder to be present in the positions of the surface atoms, which can be characterized through a single parameter, removes most of the discrepancies between experiment and theory. Further improvement might be achievable by improving the accuracy of the DW extrapolation, the model of the H2 rotational state distribution in the experimental beams, and by fine-tuning the PES. However, the question of whether the DW model is applicable to attenuation of diffractive scattering in the presence of a sizable van der Waals well (depth ≈ 50 meV) should also receive attention, in addition to the question of whether the amount of static surface disorder effectively assumed in the modeling by us could have been present in the experiments.

  7. Why a hole is like a beam splitter: A general diffraction theory for multimode quantum states of light

    Science.gov (United States)

    Xiao, Zhihao; Lanning, R. Nicholas; Zhang, Mi; Novikova, Irina; Mikhailov, Eugeniy E.; Dowling, Jonathan P.

    2017-08-01

    Within the second-quantization framework, we develop a formalism for describing a spatially multimode optical field diffracted through a spatial mask and show that this process can be described as an effective interaction between various spatial modes. We demonstrate a method to calculate the quantum state in the diffracted optical field for any given quantum state in the incident field. We also give several additional examples of how the theory works, for various quantum input states, which may be easily tested in the laboratory, including two single-mode squeezed vacuums, single- and two-photon inputs, where we show that the diffraction process produces a two-mode squeezed vacuum, number-path entanglement, and a Hong-Ou-Mandel-like effect analogous to that of a beam splitter.

  8. Optical electromagnetic vector-field modeling for the accurate analysis of finite diffractive structures of high complexity

    DEFF Research Database (Denmark)

    Dridi, Kim; Bjarklev, Anders Overgaard

    1999-01-01

    An electromagnetic vector-field modle for design of optical components based on the finite-difference-time-domain method and radiation integrals in presented. Its ability to predict the optical electromagnetic dynamics in structures with complex material distribution is demonstrated. Theoretical...

  9. The Van der Waals potential between metastable atoms and solid surfaces: novel diffraction experiments, theory

    Energy Technology Data Exchange (ETDEWEB)

    Bruhl, R.; Fouquet, P.; Grisenti, R.E.; Toennies, J.P. [Max-Planck-Institut fuer Stroemungsforschung, Goettingen (Germany); Hegerfeldt, G.C.; Kohler, T.; Stoll, M.; Walter, C. [Gottingen Universitat, Institut fur theoretische Physik, (Germany)

    2002-08-01

    Highly polarizable metastable He* (2{sup 3}S) and Ne* (2{sup 3}P) atoms have been diffracted from a 100 nm period silicon nitride transmission grating and the van der Waals coefficients C{sub 3} for the interaction of the excited atoms with the silicon nitride surface have been determined from the diffraction intensities out to the 10. order. The results agree with calculations based on the non-retarded Lifshitz formula. (authors)

  10. VECTOR THEORY AND OPTIMAL CHOICE OF ANTIMICROBIAL DRUG FOR LOCAL WOUND TREATMENT

    Directory of Open Access Journals (Sweden)

    Boyko N. N

    2016-12-01

    Full Text Available Introduction. One of important problems in the field of medicine and pharmacy is an optimal choice among several alternatives. For example, the choice of drugs for treatment among several analogs, selection of excipients among analogs for development of pharmaceutical forms with optimal pharmacological, technological and economical parameters, etc.The aim of the work is to show the possibility of vector theory use for optimal choice of antimicrobial drugs for local wound treatment among analogs taking into account several criteria at the same time. Materials and methods. For our investigation we have chosen ten drugs with antimicrobial properties for local wound treatment in different pharmaceutical forms (ointment, liniment, water and glycerin solution, tincture. We have determined antibacterial activity of drugs by agar well diffusion method on six test-stain microorganisms: Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Proteus vulgaris ATCC 4636, Bacillus subtilis ATCC 6633, and Candida albicans ATCC 885-653. Well diameter was 10 mm, the volume of drug in the well was 0.27±0.02 ml, microbial burden of agar upper layer was 107 CFU/ml, and total layer height in Petri dish was 4.0±0.5 mm. In order to integrate various qualitative and quantitative parameters into one index (vector object in multidimensional factors’ space we modify these parameters to non-dimensional normalized values. For this purpose we use a desirability theory. We have chosen the following criteria for optimal choice of the drug: antimicrobial activity (integrated index of drug’s antimicrobial activity, drug’s price, pharmacological and technological index, spectrum of drug’s action on test strains of microorganisms studied. Results and their discussions. Using vector and desirability theory, we have obtained the following range of drugs in decreasing order: Laevomecol ointment, Ioddicerinum, Tincture of Sophora

  11. Light scalar and vector mesons in the large N{sub c} limit from unitarized chiral perturbation theory

    Energy Technology Data Exchange (ETDEWEB)

    Pelaez, Jose R. [Universidad Complutense, Madrid (Spain). Dept. Fisica Teorica II

    2005-07-01

    We review the large N{sub c} behavior of light scalar and vector resonances generated from unitarized meson-meson scattering amplitudes at one loop in Chiral Perturbation Theory. The vectors nicely follow the behavior expected for qq-bar states, whereas scalar mesons do not. This suggests that the main component of light scalars is not q-barq. We also comment on t-channel vector exchange as well as on the large N{sub c} behavior of the mass splittings between the vectors generated from the inverse amplitude method. (author)

  12. On the theory of time-resolved x-ray diffraction

    DEFF Research Database (Denmark)

    Henriksen, Niels Engholm; Møller, Klaus Braagaard

    2008-01-01

    of the experimental diffraction signal for both types of X-ray sources. We present a simple analysis of time-resolved X-ray scattering for direct bond breaking in diatomic molecules. This essentially analytical approach highlights the relation between the signal and the time-dependent quantum distribution...

  13. Linking Simple Economic Theory Models and the Cointegrated Vector AutoRegressive Model

    DEFF Research Database (Denmark)

    Møller, Niels Framroze

    , it is demonstrated how other controversial hypotheses such as Rational Expectations can be formulated directly as restrictions on the CVAR-parameters. A simple example of a "Neoclassical synthetic" AS-AD model is also formulated. Finally, the partial- general equilibrium distinction is related to the CVAR as well......This paper attempts to clarify the connection between simple economic theory models and the approach of the Cointegrated Vector-Auto-Regressive model (CVAR). By considering (stylized) examples of simple static equilibrium models, it is illustrated in detail, how the theoretical model and its....... Further fundamental extensions and advances to more sophisticated theory models, such as those related to dynamics and expectations (in the structural relations) are left for future papers...

  14. Low-energy electron diffraction experiment, theory and surface structure determination

    CERN Document Server

    Hove, Michel A; Chan, Chi-Ming

    1986-01-01

    Surface crystallography plays the same fundamental role in surface science which bulk crystallography has played so successfully in solid-state physics and chemistry. The atomic-scale structure is one of the most important aspects in the understanding of the behavior of surfaces in such widely diverse fields as heterogeneous catalysis, microelectronics, adhesion, lubrication, cor­ rosion, coatings, and solid-solid and solid-liquid interfaces. Low-Energy Electron Diffraction or LEED has become the prime tech­ nique used to determine atomic locations at surfaces. On one hand, LEED has yielded the most numerous and complete structural results to date (almost 200 structures), while on the other, LEED has been regarded as the "technique to beat" by a variety of other surface crystallographic methods, such as photoemission, SEXAFS, ion scattering and atomic diffraction. Although these other approaches have had impressive successes, LEED has remained the most productive technique and has shown the most versatility...

  15. Neural-network-based depth-resolved multiscale structural optimization using density functional theory and electron diffraction data

    Science.gov (United States)

    Pennington, Robert S.; Coll, Catalina; Estradé, Sònia; Peiró, Francesca; Koch, Christoph T.

    2018-01-01

    Iterative neural-network-based three-dimensional structural optimization of atomic positions over tens of nanometers is performed using transmission electron microscope (TEM) diffraction data simulated from density functional theory (DFT) all-electron densities, thus retrieving parameter variations along the beam direction. We first use experimental data to show that the GPAW DFT code's all-electron densities are considerably more accurate for electron diffraction calculations compared to conventional isolated-atom scattering factors, and they also compare well to Wien2K DFT simulations. This DFT-TEM combination is then integrated into an iterative neural-network-optimization-based algorithm (PRIMES, parameter retrieval and inversion from multiple electron scattering) to retrieve nanometer-scale ferroelectric polarization domains and strain in theoretical bulklike specimens from TEM data. DFT and isolated-atom methods produce substantially different diffraction patterns and retrieved polarization domain parameters, and DFT is sufficient to retrieve strain properties from a silicon specimen simulated using experimentally derived structure factors. Thus, we show that the improved accuracy, fast computation, and intuitive integration make the GPAW DFT code well suited for three-dimensional materials characterization and demonstrate this using an iterative neural-network algorithm that is verifiable on the mesoscale and, with DFT integration, self-consistent on the nanoscale.

  16. Lattice thermal expansion and anisotropic displacements in 𝜶-sulfur from diffraction experiments and first-principles theory

    Science.gov (United States)

    George, Janine; Deringer, Volker L.; Wang, Ai; Müller, Paul; Englert, Ulli; Dronskowski, Richard

    2016-12-01

    Thermal properties of solid-state materials are a fundamental topic of study with important practical implications. For example, anisotropic displacement parameters (ADPs) are routinely used in physics, chemistry, and crystallography to quantify the thermal motion of atoms in crystals. ADPs are commonly derived from diffraction experiments, but recent developments have also enabled their first-principles prediction using periodic density-functional theory (DFT). Here, we combine experiments and dispersion-corrected DFT to quantify lattice thermal expansion and ADPs in crystalline α-sulfur (S8), a prototypical elemental solid that is controlled by the interplay of covalent and van der Waals interactions. We begin by reporting on single-crystal and powder X-ray diffraction measurements that provide new and improved reference data from 10 K up to room temperature. We then use several popular dispersion-corrected DFT methods to predict vibrational and thermal properties of α-sulfur, including the anisotropic lattice thermal expansion. Hereafter, ADPs are derived in the commonly used harmonic approximation (in the computed zero-Kelvin structure) and also in the quasi-harmonic approximation (QHA) which takes the predicted lattice thermal expansion into account. At the PPBE+D3(BJ) level, the QHA leads to excellent agreement with experiments. Finally, more general implications of this study for theory and experiment are discussed.

  17. Principal normal curvature of surfaces. [electromagnetic scattering and the geometrical theory of diffraction

    Science.gov (United States)

    Schmidt, R. F.

    1981-01-01

    Certain principal normal curvatures of differential geometry were developed for use in curvature matrices associated with the asymptotic solution of electromagnetic diffraction problems. The effort is directed toward microwave antenna simulations and high speed digital computer analysis of radiometric instruments used to obtain soil moisture, sea state, salinity and temperature data. It is shown that the methods used to develop the principal normal curvatures for paraboloid, hyperboloid, ellipsoid, sphere, and cone can be applied to other radiometer geometries such as the parabolic torus, even though the surface parameterizations are different. It is concluded that deployable offset geometries, distorted by rotational forces and solar loads may be analyzed by similar means given a suitable surface description.

  18. Analysis of Arbitrary Reflector Antennas Applying the Geometrical Theory of Diffraction Together with the Master Points Technique

    Directory of Open Access Journals (Sweden)

    María Jesús Algar

    2013-01-01

    Full Text Available An efficient approach for the analysis of surface conformed reflector antennas fed arbitrarily is presented. The near field in a large number of sampling points in the aperture of the reflector is obtained applying the Geometrical Theory of Diffraction (GTD. A new technique named Master Points has been developed to reduce the complexity of the ray-tracing computations. The combination of both GTD and Master Points reduces the time requirements of this kind of analysis. To validate the new approach, several reflectors and the effects on the radiation pattern caused by shifting the feed and introducing different obstacles have been considered concerning both simple and complex geometries. The results of these analyses have been compared with the Method of Moments (MoM results.

  19. Theory of in situ measurement of wave-vector-dependent dynamic susceptibility and ESR spectroscopy using the ac Josephson effect

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, S.E.; Mehran, F.

    1986-10-01

    The elementary theory of in situ measurements of the wave-vector-dependent dynamic susceptibility chi(q,..omega..) in superconductor-insulator-superconductor (SIS) and superconductor--normal-metal--superconductor (SNS) Josephson junctions is presented in some detail. The theory for more complicated SISN and SINS junctions is also described. In addition, the theory of point-contact and superconducting quantum interference device geometries, relevant to the recent experiments of Baberschke, Bures, and Barnes is developed. Involved is a detailed application of the Maxwell and London equations along with the distributed Josephson effect. In a measurement of chi(q,..omega..), the frequency ..omega.. is determined by the relation 2eV/sub 0/ = h-dash-bar..omega.. where V/sub 0/ is the voltage applied across the junction, and the wave vector q is determined by the relation 2edB/sub 0/ = h-dash-barq where d is the effective width of the junction and B/sub 0/ is the magnetic field applied perpendicular to the direction of the current. The relative merits of the different types of junctions are discussed and the expected signal strengths are estimated. The limitations for the maximum measurable frequency and wave vector are also given. It seems probable that the proposed technique can be used to measure spin-wave branches from zero wave vector up to about 10% of the way to the Brillouin zone edge.

  20. Support vector machine classification of major depressive disorder using diffusion-weighted neuroimaging and graph theory.

    Science.gov (United States)

    Sacchet, Matthew D; Prasad, Gautam; Foland-Ross, Lara C; Thompson, Paul M; Gotlib, Ian H

    2015-01-01

    Recently, there has been considerable interest in understanding brain networks in major depressive disorder (MDD). Neural pathways can be tracked in the living brain using diffusion-weighted imaging (DWI); graph theory can then be used to study properties of the resulting fiber networks. To date, global abnormalities have not been reported in tractography-based graph metrics in MDD, so we used a machine learning approach based on "support vector machines" to differentiate depressed from healthy individuals based on multiple brain network properties. We also assessed how important specific graph metrics were for this differentiation. Finally, we conducted a local graph analysis to identify abnormal connectivity at specific nodes of the network. We were able to classify depression using whole-brain graph metrics. Small-worldness was the most useful graph metric for classification. The right pars orbitalis, right inferior parietal cortex, and left rostral anterior cingulate all showed abnormal network connectivity in MDD. This is the first use of structural global graph metrics to classify depressed individuals. These findings highlight the importance of future research to understand network properties in depression across imaging modalities, improve classification results, and relate network alterations to psychiatric symptoms, medication, and comorbidities.

  1. Validation of molecular crystal structures from powder diffraction data with dispersion-corrected density functional theory (DFT-D).

    Science.gov (United States)

    van de Streek, Jacco; Neumann, Marcus A

    2014-12-01

    In 2010 we energy-minimized 225 high-quality single-crystal (SX) structures with dispersion-corrected density functional theory (DFT-D) to establish a quantitative benchmark. For the current paper, 215 organic crystal structures determined from X-ray powder diffraction (XRPD) data and published in an IUCr journal were energy-minimized with DFT-D and compared to the SX benchmark. The on average slightly less accurate atomic coordinates of XRPD structures do lead to systematically higher root mean square Cartesian displacement (RMSCD) values upon energy minimization than for SX structures, but the RMSCD value is still a good indicator for the detection of structures that deserve a closer look. The upper RMSCD limit for a correct structure must be increased from 0.25 Å for SX structures to 0.35 Å for XRPD structures; the grey area must be extended from 0.30 to 0.40 Å. Based on the energy minimizations, three structures are re-refined to give more precise atomic coordinates. For six structures our calculations provide the missing positions for the H atoms, for five structures they provide corrected positions for some H atoms. Seven crystal structures showed a minor error for a non-H atom. For five structures the energy minimizations suggest a higher space-group symmetry. For the 225 SX structures, the only deviations observed upon energy minimization were three minor H-atom related issues. Preferred orientation is the most important cause of problems. A preferred-orientation correction is the only correction where the experimental data are modified to fit the model. We conclude that molecular crystal structures determined from powder diffraction data that are published in IUCr journals are of high quality, with less than 4% containing an error in a non-H atom.

  2. Amplitude, phase, location and orientation calibration of an acoustic vector sensor array, part I: Theory

    NARCIS (Netherlands)

    Xu, B.; Wind, J.; Bree, H.E. de; Basten, T.G.H.; Druyvesteyn, E.

    2010-01-01

    An acoustic vector sensor array consists of multiple sound pressure microphones and particle velocity sensors. A pressure microphone usually has an omni-directional response, yet a particle velocity sensor is directional. Currently, acoustic vector sensor arrays are under investigation for far field

  3. Elementary vectors

    CERN Document Server

    Wolstenholme, E Œ

    1978-01-01

    Elementary Vectors, Third Edition serves as an introductory course in vector analysis and is intended to present the theoretical and application aspects of vectors. The book covers topics that rigorously explain and provide definitions, principles, equations, and methods in vector analysis. Applications of vector methods to simple kinematical and dynamical problems; central forces and orbits; and solutions to geometrical problems are discussed as well. This edition of the text also provides an appendix, intended for students, which the author hopes to bridge the gap between theory and appl

  4. Dynamical diffraction in periodic multilayers

    CERN Document Server

    Sears, V F

    1997-01-01

    Exact reflectivity curves are calculated numerically for various periodic multilayers using the optical matrix method in order to test the dynamical theory of diffraction. The theory is generally valid for values of the bilayer thickness d up to about 100 A. For somewhat larger values of d, where the theory begins to break down, the initial discrepancy is in the phase of the oscillations in the wings of the peaks. For very large values of d, where the first-order Bragg peak approaches the edge of the mirror reflection, two general types of multilayers can be distinguished. In the first (typified in the present work by Ni/Ti), there is a large (30% or more) reduction in the actual value of the critical wave vector for total reflection while, in the second (typified here by Fe/Ge), there is very little reduction (3 % or so). The origin of these two very different types of behavior is explained. It is also shown that, within the dynamical theory of diffraction, the change in the position of the center of the Dar...

  5. Unveiling the nature of post-linear response Z-vector method for time-dependent density functional theory

    Science.gov (United States)

    Pastore, Mariachiara; Assfeld, Xavier; Mosconi, Edoardo; Monari, Antonio; Etienne, Thibaud

    2017-07-01

    We report a theoretical study on the analysis of the relaxed one-particle difference density matrix characterizing the passage from the ground to the excited state of a molecular system, as obtained from time-dependent density functional theory. In particular, this work aims at using the physics contained in the so-called Z-vector, which differentiates between unrelaxed and relaxed difference density matrices to analyze excited states' nature. For this purpose, we introduce novel quantum-mechanical quantities, based on the detachment/attachment methodology, for analysing the Z-vector transformation for different molecules and density functional theory functionals. A derivation pathway of these novel descriptors is reported, involving a numerical integration to be performed in the Euclidean space on the density functions. This topological analysis is then applied to two sets of chromophores, and the correlation between the level of theory and the behavior of our descriptors is properly rationalized. In particular, the effect of range-separation on the relaxation amplitude is discussed. The relaxation term is finally shown to be system-specific (for a given level of theory) and independent of the number of electrons (i.e., the relaxation amplitude is not simply the result of a collective phenomenon).

  6. An analysis of the radiation from apertures in curved surfaces by the geometrical theory of diffraction. [ray technique for electromagnetic fields

    Science.gov (United States)

    Pathak, P. H.; Kouyoumjian, R. G.

    1974-01-01

    In this paper the geometrical theory of diffraction is extended to treat the radiation from apertures of slots in convex perfectly conducting surfaces. It is assumed that the tangential electric field in the aperture is known so that an equivalent infinitesimal source can be defined at each point in the aperture. Surface rays emanate from this source which is a caustic of the ray system. A launching coefficient is introduced to describe the excitation of the surface ray modes. If the field radiated from the surface is desired, the ordinary diffraction coefficients are used to determine the field of the rays shed tangentially from the surface rays. The field of the surface ray modes is not the field on the surface; hence if the mutual coupling between slots is of interest, a second coefficient related to the launching coefficient must be employed. In the region adjacent to the shadow boundary, the component of the field directly radiated from the source is represented by Fock-type functions. In the illuminated region the incident radiation from the source (this does not include the diffracted field components) is treated by geometrical optics. This extension of the geometrical theory of diffraction is applied to calculate the radiation from slots on elliptic cylinders, spheres, and spheroids.

  7. Parity violating flavour changing neutral current and natural conservation of strangeness in vector-like theories

    CERN Document Server

    Fritzsch, Harald

    1977-01-01

    Two vector-like schemes of the weak interactions, based on five and seven quarks, respectively, are studied in which the suppression of mod Delta S mod =1 neutral currents is natural and in which the neutral current interaction violates parity. Various aspects (parity violation, flavour changing neutral current, ' nu anomaly', masses of the W and Z bosons) are investigated. (17 refs).

  8. Surprises in aperiodic diffraction

    Science.gov (United States)

    Baake, Michael; Grimm, Uwe

    2010-04-01

    Mathematical diffraction theory is concerned with the diffraction image of a given structure and the corresponding inverse problem of structure determination. In recent years, the understanding of systems with continuous and mixed spectra has improved considerably. Moreover, the phenomenon of homometry shows various unexpected new facets. Here, we report on some of the recent results in an exemplary and informal fashion.

  9. Surprises in aperiodic diffraction

    OpenAIRE

    Baake, Michael; Grimm, Uwe

    2009-01-01

    Mathematical diffraction theory is concerned with the diffraction image of a given structure and the corresponding inverse problem of structure determination. In recent years, the understanding of systems with continuous and mixed spectra has improved considerably. Moreover, the phenomenon of homometry shows various unexpected new facets. Here, we report on some of the recent results in an exemplary and informal fashion.

  10. Surprises from complete vector portal theories: New insights into the dark sector and its interplay with Higgs physics

    Science.gov (United States)

    Cui, Yanou; D'Eramo, Francesco

    2017-11-01

    We study UV complete theories where the standard model (SM) gauge group is extended with a new Abelian U (1 )',and the field content is augmented by an arbitrary number of scalar and fermion SM singlets, potentially including dark matter (DM) candidates. Considerations such as classical and quantum gauge invariance of the full theory and S-matrix unitarity, not applicable within a simplified model approach, are shown to have significant phenomenological consequences. The lack of gauge anomalies leads to compact relations among the U (1 )' fermion charges and puts a lower bound on the number of dark fermions. Contrary to naive expectations, the DM annihilation to Z h is found to be p-wave suppressed, as hinted by the perturbative unitarity of the S-matrix, with dramatic implications for DM thermal relic density and indirect searches. Within this framework, the interplay between dark matter, new vector boson, and Higgs physics is rather natural and generic.

  11. Vector multiplets and the phases of N = 2 theories in 2D through the looking glass

    Science.gov (United States)

    Gates, S. J., Jr.

    1995-02-01

    We extend Witten's discussion of actions related to the Landau-Ginzburg description of Calabi-Yau hypersurfaces in weighted projective spaces to cover the mirror class of models that include twisted chiral matter multiplets and a newly discovered 2D, N = 2 twisted vector multiplet. Certain integrability obstructions are observed that constrain the most general constructions containing both matter and twisted matter simultaneously. It is conjectured that knot invariants will ultimately play a role in describing the most general such model.

  12. Self-mass of vector bosons in gravity-modified quantum field theories

    Energy Technology Data Exchange (ETDEWEB)

    Poelt, P. (Technische Univ., Graz (Austria). Inst. fuer Theoretische Physik)

    1985-01-01

    The self-mass of the W-boson is calculated using a gravitational modified Weinberg-Salam theory with an anomalous magnetic moment assumed to be variable. The self-mass is shown to be finite with Gsub(N)sup(-1/2) (Gsub(N) Newton's gravitational constant) as the cutoff parameter. But only certain values of the anomalous magnetic moment yield a correct order of magnitude. Lowest order of perturbation theory gives complex solutions for these magnetic moments. Nevertheless, additional terms of higher perturbation theory will modify the equation for the magnetic moment and possibly lead to the definite magnetic moment of the W-boson of the non-modified Weinberg-Salam theory.

  13. Detecting diffusion-diffraction patterns in size distribution phantoms using double-pulsed field gradient NMR: Theory and experiments

    OpenAIRE

    Shemesh, Noam; Özarslan, Evren; Basser, Peter J.; Cohen, Yoram

    2010-01-01

    NMR observable nuclei undergoing restricted diffusion within confining pores are important reporters for microstructural features of porous media including, inter-alia, biological tissues, emulsions and rocks. Diffusion NMR, and especially the single-pulsed field gradient (s-PFG) methodology, is one of the most important noninvasive tools for studying such opaque samples, enabling extraction of important microstructural information from diffusion-diffraction phenomena. However, when the pores...

  14. Deformations of quantum field theories on spacetimes with Killing vector fields

    Energy Technology Data Exchange (ETDEWEB)

    Dappiaggi, Claudio [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; Lechner, Gandalf [Wien Univ. (Austria). Fakultaet fuer Physik; Morfa-Morales, Eric [Erwin Schroedinger Institut fuer Mathematische Physik, Wien (Austria)

    2010-06-15

    The recent construction and analysis of deformations of quantum field theories by warped convolutions is extended to a class of curved spacetimes. These spacetimes carry a family of wedge-like regions which share the essential causal properties of the Poincare transforms of the Rindler wedge in Minkowski space. In the setting of deformed quantum field theories, they play the role of typical localization regions of quantum fields and observables. As a concrete example of such a procedure, the deformation of the free Dirac field is studied. (orig.)

  15. Quantum interferences revealed by neutron diffraction accord with a macroscopic-scale quantum-theory of ferroelectrics KH2(1- ρ)D2 ρ PO4

    Science.gov (United States)

    Fillaux, François; Cousson, Alain

    2016-03-01

    Neutron diffraction by single-crystals KH2(1- ρ)D2 ρ PO4 at 293 K reveal quantum interferences consistent with a static lattice of entangled proton-deuteron scatterers. These crystals are represented by a macroscopic-scale condensate of phonons with continuous space-time-translation symmetry and zero-entropy. This state is energetically favored and decoherence-free over a wide temperature-range. Projection of the crystal state onto a basis of four electrically- and isotopically-distinct state-vectors accounts for isotope and pressure effects on the temperature of the ferroelectric-dielectric transition, as well as for the latent heat. At the microscopic level, an incoming wave realizes a transitory state either in the space of static positional parameters (elastic scattering) or in that of the symmetry species (energy transfer). Neutron diffraction, vibrational spectroscopy, relaxometry and neutron Compton scattering support the conclusion that proton and deuteron scatterers are separable exclusively through resonant energy-transfer.

  16. Causality of spacetimes admitting a parallel null vector and weak KAM theory

    CERN Document Server

    Minguzzi, E

    2012-01-01

    The causal spacetimes admitting a covariantly constant null vector provide a connection between relativistic and non-relativistic physics. We explore this relationship in several directions. We start proving a formula which relates the Lorentzian distance in the full spacetime with the least action of a mechanical system living in a quotient classical space time. The timelike eikonal equation satisfied by the Lorentzian distance is proved to be equivalent to the Hamilton-Jacobi equation for the least action. We also prove that the Legendre transform on the classical base corresponds to the musical isomorphism on the light cone, and the Young-Fenchel inequality is nothing but a well known geometric inequality in Lorentzian geometry. A strategy to simplify the dynamics passing to a reference frame moving with the E.-L. flow is explained. It is then proved that the causality properties can be conveniently expressed in terms of the least action. In particular, strong causality coincides with stable causality and ...

  17. Singular vectors and topological theories from Virasoro constraints via the Kontsevich-Miwa transform

    CERN Document Server

    Gato-Rivera, B.

    1993-01-01

    We use the Kontsevich-Miwa transform to relate the different pictures describing matter coupled to topological gravity in two dimensions: topological theories, Virasoro constraints on integrable hierarchies, and a DDK-type formalism. With the help of the Kontsevich-Miwa transform, we solve the Virasoro constraints on the KP hierarchy in terms of minimal models dressed with a (free) Liouville-like scalar. The dressing prescription originates in a topological (twisted N=2) theory. The Virasoro constraints are thus related to essentially the N=2 null state decoupling equations. The N=2 generators are constructed out of matter, the `Liouville' scalar, and $c=-2$ ghosts. By a `dual' construction involving the reparametrization $c=-26$ ghosts, the DDK dressing prescription is reproduced from the N=2 symmetry. As a by-product we thus observe that there are two ways to dress arbitrary $d\\leq1$ or $d\\geq25$ matter theory, that allow its embedding into a topological theory. By th e Kontsevich-Miwa transform, which intr...

  18. An accurate density functional theory calculation for electronic excitation energies: the least-squares support vector machine.

    Science.gov (United States)

    Gao, Ting; Sun, Shi-Ling; Shi, Li-Li; Li, Hui; Li, Hong-Zhi; Su, Zhong-Min; Lu, Ying-Hua

    2009-05-14

    Support vector machines (SVMs), as a novel type of learning machine, has been very successful in pattern recognition and function estimation problems. In this paper we introduce least-squares (LS) SVMs to improve the calculation accuracy of density functional theory. As a demonstration, this combined quantum mechanical calculation with LS-SVM correction approach has been applied to evaluate the electronic excitation energies of 160 organic molecules. The newly introduced LS-SVM approach reduces the root-mean-square deviation of the calculated electronic excitation energies of 160 organic molecules from 0.32 to 0.11 eV for the B3LYP/6-31G(d) calculation. Thus, the LS-SVM correction on top of B3LYP/6-31G(d) is a better method to correct electronic excitation energies and can be used as the approximation of experimental results which are impossible to obtain experimentally.

  19. Multitrace Deformations of Vector and Adjoint Theories and their Holographic Duals

    CERN Document Server

    Elitzur, S; Porrati, M; Rabinovici, Eliezer

    2006-01-01

    We present general methods to study the effect of multitrace deformations in conformal theories admitting holographic duals in Anti de Sitter space. In particular, we analyse the case that these deformations introduce an instability both in the bulk AdS space and in the boundary CFT. We also argue that multitrace deformations of the O(N) linear sigma model in three dimensions correspond to nontrivial time-dependent backgrounds in certain theories of infinitely many interacting massless fields on AdS_4, proposed years ago by Fradkin and Vasiliev. We point out that the phase diagram of a truly marginal large-N deformation has an infrared limit in which only an O(N) singlet field survives. We draw from this case lessons on the full string-theoretical interpretation of instabilities of the dual boundary theory and exhibit a toy model that resolves the instability of the O(N) model, generated by a marginal multitrace deformation. The resolution suggests that the instability may not survive in an appropriate UV com...

  20. Studies into equine electrocardiography and vectorcardiography: I. Cardiac electric forces and the dipole vector theory.

    Science.gov (United States)

    Holmes, J R; Alps, B J

    1967-04-01

    Theoretical consideration has been given in two horses to the properties of the electric field created by the equine heart acting as a simple electric generator. The principles of the vectorial theory have been applied to test the validity of application of the dipole concept. The cardiac electric forces, althrough complex in the immediate region of the heart, appear at the body surface in a similar form to those arising from a relatively immobile, single equivalent dipole. The potential value of the technique of vectorcardiography in cardiological investigations is briefly discussed.

  1. Diffraction analysis for digital micromirror device scene projectors in the long-wave infrared

    Science.gov (United States)

    Han, Qing; Wang, Jian; Zhang, Jianzhong; Sun, Qiang

    2016-08-01

    Diffraction effects play a significant role in scene projectors by digital micromirror devices (DMDs) in the long-wave infrared (IR) band (8 to 12 μm). The contrast provided by these projector systems can become noticeably worse because of the diffraction characteristics of the DMD. The actual diffraction characteristics of the DMD deviate significantly from the predictions of scalar diffraction theory in the long-wave IR. To address this issue, we built a vector diffraction-grating model of the DMD; the diffraction grating model is simulated with MATLAB. Furthermore, we analyze the effect of incident angle and polarization, which are the main factors that decrease the contrast of DMD-based scene projectors in the long-wave IR. Finally, an effective method to improve the contrast of the scene projector system is given, and the maximum contrast of the scene projector system is ˜0.7.

  2. Non-diffractive waves

    CERN Document Server

    Hernandez-Figueroa, Hugo E; Recami, Erasmo

    2013-01-01

    This continuation and extension of the successful book ""Localized Waves"" by the same editors brings together leading researchers in non-diffractive waves to cover the most important results in their field and as such is the first to present the current state.The well-balanced presentation of theory and experiments guides readers through the background of different types of non-diffractive waves, their generation, propagation, and possible applications. The authors include a historical account of the development of the field, and cover different types of non-diffractive waves, including Airy

  3. VECTOR INTEGRATION

    NARCIS (Netherlands)

    Thomas, E. G. F.

    2012-01-01

    This paper deals with the theory of integration of scalar functions with respect to a measure with values in a, not necessarily locally convex, topological vector space. It focuses on the extension of such integrals from bounded measurable functions to the class of integrable functions, proving

  4. Analysis of structure and vibrational dynamics of the BeTe(001) surface using X-ray diffraction, Raman spectroscopy, and density functional theory

    DEFF Research Database (Denmark)

    Kumpf, C.; Müller, A.; Weigand, W.

    2003-01-01

    in the underlying Te layer. The Be-rich surface exhibits a (4 X 1) periodicity with alternating Te dimers and Te-Be-Te trimers. A vibration eigenfrequency of 165 cm(-1) is observed for the Te-rich surface, while eigenmodes at 157 and 188 cm(-1) are found for the Be-rich surface. The experimentally derived atomic......The atomic structure and lattice dynamics of epitaxial BeTe(001) thin films are derived from surface x-ray diffraction and Raman spectroscopy. On the Te-rich BeTe(001) surface [1 (1) over bar0]-oriented Te dimers are identified. They cause a (2 X 1) superstructure and induce a pronounced buckling...... geometry and the vibration modes are in very good agreement with the results of density functional theory calculations....

  5. Validation of missed space-group symmetry in X-ray powder diffraction structures with dispersion-corrected density functional theory.

    Science.gov (United States)

    Hempler, Daniela; Schmidt, Martin U; van de Streek, Jacco

    2017-08-01

    More than 600 molecular crystal structures with correct, incorrect and uncertain space-group symmetry were energy-minimized with dispersion-corrected density functional theory (DFT-D, PBE-D3). For the purpose of determining the correct space-group symmetry the required tolerance on the atomic coordinates of all non-H atoms is established to be 0.2 Å. For 98.5% of 200 molecular crystal structures published with missed symmetry, the correct space group is identified; there are no false positives. Very small, very symmetrical molecules can end up in artificially high space groups upon energy minimization, although this is easily detected through visual inspection. If the space group of a crystal structure determined from powder diffraction data is ambiguous, energy minimization with DFT-D provides a fast and reliable method to select the correct space group.

  6. Examination of Phencyclidine Hydrochloride via Cryogenic Terahertz Spectroscopy, Solid-State Density Functional Theory, and X-ray Diffraction

    Science.gov (United States)

    Hakey, Patrick M.; Hudson, Matthew R.; Allis, Damian G.; Ouellette, Wayne; Korter, Timothy M.

    2009-10-01

    The terahertz (THz) spectrum of phencyclidine hydrochloride from 7.0 to 100.0 cm-1 has been measured at cryogenic (78.4 K) temperature. The complete structural analysis and vibrational assignment of the compound have been performed employing solid-state density functional theory utilizing eight generalized gradient approximation density functionals and both solid-state and isolated-molecule methods. The structural results and the simulated spectra display the substantial improvement obtained by using solid-state simulations to accurately assign and interpret solid-state THz spectra. A complete assignment of the spectral features in the measured THz spectrum has been completed at a VWN-BP/DNP level of theory, with the VWN-BP density functional providing the best-fit solid-state simulation of the experimentally observed spectrum. The cryogenic THz spectrum contains eight spectral features that, at the VWN-BP/DNP level, consist of 15 infrared-active vibrational modes. Of the calculated modes, external crystal vibrations are predicted to account for 42% of the total spectral intensity.

  7. Formulation of dynamical theory of X-ray diffraction for perfect crystals in the Laue case using the Riemann surface.

    Science.gov (United States)

    Saka, Takashi

    2016-05-01

    The dynamical theory for perfect crystals in the Laue case was reformulated using the Riemann surface, as used in complex analysis. In the two-beam approximation, each branch of the dispersion surface is specified by one sheet of the Riemann surface. The characteristic features of the dispersion surface are analytically revealed using four parameters, which are the real and imaginary parts of two quantities specifying the degree of departure from the exact Bragg condition and the reflection strength. By representing these parameters on complex planes, these characteristics can be graphically depicted on the Riemann surface. In the conventional case, the absorption is small and the real part of the reflection strength is large, so the formulation is the same as the traditional analysis. However, when the real part of the reflection strength is small or zero, the two branches of the dispersion surface cross, and the dispersion relationship becomes similar to that of the Bragg case. This is because the geometrical relationships among the parameters are similar in both cases. The present analytical method is generally applicable, irrespective of the magnitudes of the parameters. Furthermore, the present method analytically revealed many characteristic features of the dispersion surface and will be quite instructive for further numerical calculations of rocking curves.

  8. Calculating cellulose diffraction patterns

    Science.gov (United States)

    Although powder diffraction of cellulose is a common experiment, the patterns are not widely understood. The theory is mathematical, there are numerous different crystal forms, and the conventions are not standardized. Experience with IR spectroscopy is not directly transferable. An awful error, tha...

  9. Advances in structure research by diffraction methods

    CERN Document Server

    Brill, R

    1970-01-01

    Advances in Structure Research by Diffraction Methods reviews advances in the use of diffraction methods in structure research. Topics covered include the dynamical theory of X-ray diffraction, with emphasis on Ewald waves in theory and experiment; dynamical theory of electron diffraction; small angle scattering; and molecular packing. This book is comprised of four chapters and begins with an overview of the dynamical theory of X-ray diffraction, especially in terms of how it explains all the absorption and propagation properties of X-rays at the Bragg setting in a perfect crystal. The next

  10. Neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Heger, G. [Rheinisch-Westfaelische Technische Hochschule Aachen, Inst. fuer Kristallographie, Aachen (Germany)

    1996-12-31

    X-ray diffraction using conventional laboratory equipment and/or synchrotron installations is the most important method for structure analyses. The purpose of this paper is to discuss special cases, for which, in addition to this indispensable part, neutrons are required to solve structural problems. Even though the huge intensity of modern synchrotron sources allows in principle the study of magnetic X-ray scattering the investigation of magnetic structures is still one of the most important applications of neutron diffraction. (author) 15 figs., 1 tab., 10 refs.

  11. Diffraction Techniques.

    Science.gov (United States)

    1983-08-30

    diffraction of electrons were recognized within a few included. A nubr of reviews exist on various aspects of surface years of the Davisson - Germer ...in our understanding of surface 1. C. J. Davisson and L. It. Germer , Phys. Rev. 30, 705 (1927). crystallography and in the development of experimental

  12. A hybrid method combining the Time-Domain Method of Moments, the Time-Domain Uniform Theory of Diffraction and the FDTD

    Directory of Open Access Journals (Sweden)

    A. Becker

    2007-06-01

    Full Text Available In this paper a hybrid method combining the Time-Domain Method of Moments (TD-MoM, the Time-Domain Uniform Theory of Diffraction (TD-UTD and the Finite-Difference Time-Domain Method (FDTD is presented. When applying this new hybrid method, thin-wire antennas are modeled with the TD-MoM, inhomogeneous bodies are modelled with the FDTD and large perfectly conducting plates are modelled with the TD-UTD. All inhomogeneous bodies are enclosed in a so-called FDTD-volume and the thin-wire antennas can be embedded into this volume or can lie outside. The latter avoids the simulation of white space between antennas and inhomogeneous bodies. If the antennas are positioned into the FDTD-volume, their discretization does not need to agree with the grid of the FDTD. By using the TD-UTD large perfectly conducting plates can be considered efficiently in the solution-procedure. Thus this hybrid method allows time-domain simulations of problems including very different classes of objects, applying the respective most appropriate numerical techniques to every object.

  13. Radiation Characteristics of Cavity Backed Aperture Antennas in Finite Ground Plane Using the Hybrid FEM/MoM Technique and Geometrical Theory of Diffraction

    Science.gov (United States)

    Reddy, C. J.; Deshpande, M. D.; Cockrell, C. R.; Beck, F. B.

    1996-01-01

    A technique using hybrid Finite Element Method (FEM)/Method of Moments (MoM), and Geometrical Theory of Diffraction (GTD) is presented to analyze the radiation characteristics of cavity fed aperture antennas in a finite ground plane. The cavity which excites the aperture is assumed to be fed by a cylindrical transmission line. The electromagnetic (EM) fields inside the cavity are obtained using FEM. The EM fields and their normal derivatives required for FEM solution are obtained using (1) the modal expansion in the feed region and (2) the MoM for the radiating aperture region(assuming an infinite ground plane). The finiteness of the ground plane is taken into account using GTD. The input admittance of open ended circular, rectangular, and coaxial line radiating into free space through an infinite ground plane are computed and compared with earlier published results. Radiation characteristics of a coaxial cavity fed circular aperture in a finite rectangular ground plane are verified with experimental results.

  14. Vector and axial vector mesons at finite temperature

    OpenAIRE

    mallik, S.; Sarkar, Sourav

    2002-01-01

    We consider the thermal correlation functions of vector and axial-vector currents and evaluate corrections to the vector and axial-vector meson pole terms to one loop in chiral perturbation theory. As expected, the pole positions do not shift to leading order in temperature. But the residues decrease with temperature.

  15. Powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Hart, M.

    1995-12-31

    the importance of x-ray powder diffraction as an analytical tool for phase identification of materials was first pointed out by Debye and Scherrer in Germany and, quite independently, by Hull in the US. Three distinct periods of evolution lead to ubiquitous application in many fields of science and technology. In the first period, until the mid-1940`s, applications were and developed covering broad categories of materials including inorganic materials, minerals, ceramics, metals, alloys, organic materials and polymers. During this formative period, the concept of quantitative phase analysis was demonstrated. In the second period there followed the blossoming of technology and commercial instruments became widely used. The history is well summarized by Parrish and by Langford and Loueer. By 1980 there were probably 10,000 powder diffractometers in routine use, making it the most widely used of all x-ray crystallographic instruments. In the third, present, period data bases became firmly established and sophisticated pattern fitting and recognition software made many aspects of powder diffraction analysis routine. High resolution, tunable powder diffractometers were developed at sources of synchrotron radiation. The tunability of the spectrum made it possible to exploit all the subtleties of x-ray spectroscopy in diffraction experiments.

  16. Diffraction radiation from relativistic particles

    CERN Document Server

    Potylitsyn, Alexander Petrovich; Strikhanov, Mikhail Nikolaevich; Tishchenko, Alexey Alexandrovich

    2010-01-01

    This book deals with diffraction radiation, which implies the boundary problems of electromagnetic radiation theory. Diffraction radiation is generated when a charged particle moves in a vacuum near a target edge. Diffraction radiation of non-relativistic particles is widely used to design intense emitters in the cm wavelength range. Diffraction radiation from relativistic charged particles is important for noninvasive beam diagnostics and design of free electron lasers based on Smith-Purcell radiation which is diffraction radiation from periodic structures. Different analytical models of diffraction radiation and results of recent experimental studies are presented in this book. The book may also serve as guide to classical electrodynamics applications in beam physics and electrodynamics. It can be of great use for young researchers to develop skills and for experienced scientists to obtain new results.

  17. Multiple scattering effects with cyclical terms in active remote sensing of vegetated surface using vector radiative transfer theory

    Science.gov (United States)

    The energy transport in a vegetated (corn) surface layer is examined by solving the vector radiative transfer equation using a numerical iterative approach. This approach allows a higher order that includes the multiple scattering effects. Multiple scattering effects are important when the optical t...

  18. Photon diffraction

    Science.gov (United States)

    Hodge, John

    2009-11-01

    In current light models, a particle-like model of light is inconsistent with diffraction observations. A model of light is proposed wherein photon inferences are combined with the cosmological scalar potential model (SPM). That the photon is a surface with zero surface area in the travel direction is inferred from the Michelson-Morley experiment. That the photons in slits are mathematically treated as a linear antenna array (LAA) is inferred from the comparison of the transmission grating interference pattern and the single slit diffraction pattern. That photons induce a LAA wave into the plenum is inferred from the fractal model. Similarly, the component of the photon (the hod) is treated as a single antenna radiating a potential wave into the plenum. That photons are guided by action on the surface of the hod is inferred from the SPM. The plenum potential waves are a real field (not complex) that forms valleys, consistent with the pilot waves of the Bohm interpretation of quantum mechanics. Therefore, the Afshar experiment result is explained, supports Bohm, and falsifies Copenhagen. The papers may be viewed at http://web.citcom.net/˜scjh/.

  19. Crystal Structure of 17α-Dihydroequilin, C18H22O2, from Synchrotron Powder Diffraction Data and Density Functional Theory

    Directory of Open Access Journals (Sweden)

    James A. Kaduk

    2017-07-01

    Full Text Available The crystal structure of 17α-dihydroequilin has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. 17α-dihydroequilin crystallizes in space group P212121 (#19 with a = 6.76849(1 Å, b = 8.96849(1 Å, c = 23.39031(5 Å, V = 1419.915(3 Å3, and Z = 4. Both hydroxyl groups form hydrogen bonds to each other, resulting in zig-zag chains along the b-axis. The powder diffraction pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ as the entry 00-066-1608.

  20. Crystal Structure of 17α-Dihydroequilin, C18H22O2, from Synchrotron Powder Diffraction Data and Density Functional Theory

    Energy Technology Data Exchange (ETDEWEB)

    Kaduk, James; Gindhart, Amy; Blanton, Thomas

    2017-07-01

    The crystal structure of 17α-dihydroequilin has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. 17α-dihydroequilin crystallizes in space group P212121 (#19) with a = 6.76849(1) Å, b = 8.96849(1) Å, c = 23.39031(5) Å, V = 1419.915(3) Å3, and Z = 4. Both hydroxyl groups form hydrogen bonds to each other, resulting in zig-zag chains along the b-axis. The powder diffraction pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ as the entry 00-066-1608.

  1. Description of diffraction grating experiments for photons and electrons in Feynman's space-time formulation of quantum mechanics: The quantum origins of classical wave theories of light and massive particles

    OpenAIRE

    Field, J H.

    2013-01-01

    The five laws of relativistic quantum mechanics, according to Feynman's path integral formulation, are concisely stated and applied to experiments. Reflection diffraction grating experiments for both photons and electrons are analysed, in particular the Davisson-Germer experiment in which the wave-like property of electrons was first established. It is shown how classical, purely spatial, effective wave theories for both photons and electrons are predicted by the path integral formulation of ...

  2. Grazing incidence diffraction : A review

    Energy Technology Data Exchange (ETDEWEB)

    Gilles, B. [LTPCM, ENSEEG. St. Martin d`Heres. (France)

    1996-09-01

    Different Grazing Incidence Diffraction (GID) methods for the analysis of thin films and multilayer structures are reviewed in three sections: the reflectivity is developed in the first one, which includes the non-specular diffuse scattering. The second one is devoted to the extremely asymmetric Bragg diffraction and the third one to the in-plane Bragg diffraction. Analytical formulations of the scattered intensities are developed for each geometry, in the framework of the kinetical analysis as well as the dynamical theory. Experimental examples are given to illustrate the quantitative possibility of the GID techniques.

  3. Nucleon and Delta axial-vector couplings in 1/N{sub c}-Baryon Chiral Perturbation Theory

    Energy Technology Data Exchange (ETDEWEB)

    Goity, Jose Luis [JLAB; Calle Cordon, Alvaro [JLAB

    2013-08-01

    In this contribution, baryon axial-vector couplings are studied in the framework of the combined 1/N{sub c} and chiral expansions. This framework is implemented on the basis of the emergent spin-flavor symmetry in baryons at large N{sub c} and HBChPT, and linking both expansions ({xi}-expansion), where 1/N{sub c} is taken to be a quantity order p. The study is carried out including one-loop contributions, which corresponds to order xi to the third for baryon masses and order {xi} square for the axial couplings.

  4. A neutron diffraction study of the crystal of benzoic acid from 6 to 293 K and a macroscopic-scale quantum theory of the lattice of hydrogen-bonded dimers

    Energy Technology Data Exchange (ETDEWEB)

    Fillaux, François, E-mail: francois.fillaux@upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, MONARIS, F-7505 Paris (France); Cousson, Alain, E-mail: alain-f.cousson@cea.fr [Laboratoire Léon Brillouin (CEA-CNRS), C.E. Saclay, 91191 Gif-sur-Yvette cedex (France)

    2016-11-10

    Highlights: • Proton transfer and tautomerism are revisited from quantum viewpoint. • Neutron-diffraction gives evidence for long-range correlations for protons. • We introduce a decoherence-free macroscopic-scale crystal-state. • All observations accord with the principle of complementarity. • Computational-chemistry models are inappropriate. - Abstract: Measurements via different techniques of the crystal of benzoic acid have led to conflicting conceptions of tautomerism: statistical disorder for diffraction; semiclassical jumps for relaxometry; quantum states for vibrational spectroscopy. We argue that these conflicts follow from the prejudice that nuclear positions and eigenstates are pre-existing to measurements, what is at variance with the principle of complementarity. We propose a self-contained quantum theory. First of all, new single-crystal neutron-diffraction data accord with long-range correlation for proton-site occupancies. Then we introduce a macroscopic-scale quantum-state emerging from phonon condensation, for which nuclear positions and eigenstates are indefinite. As to quantum-measurements, an incoming wave (neutron or photon) entangled with the condensate realizes a transitory state, either in the space of static nuclear-coordinates (diffraction), or in that of the symmetry coordinates (spectroscopy and relaxometry). We derive temperature-laws for proton-site occupancies and for the relaxation rate, which compare favorably with measurements.

  5. Complex Polynomial Vector Fields

    DEFF Research Database (Denmark)

    Dias, Kealey

    The two branches of dynamical systems, continuous and discrete, correspond to the study of differential equations (vector fields) and iteration of mappings respectively. In holomorphic dynamics, the systems studied are restricted to those described by holomorphic (complex analytic) functions...... or meromorphic (allowing poles as singularities) functions. There already exists a well-developed theory for iterative holomorphic dynamical systems, and successful relations found between iteration theory and flows of vector fields have been one of the main motivations for the recent interest in holomorphic...... vector fields. Since the class of complex polynomial vector fields in the plane is natural to consider, it is remarkable that its study has only begun very recently. There are numerous fundamental questions that are still open, both in the general classification of these vector fields, the decomposition...

  6. Poynting vector profile of a tightly focused radially polarized beam in the presence of primary aberrations.

    Science.gov (United States)

    Gaffar, M; Boruah, Bosanta R

    2015-04-01

    The Poynting vector profile of a tightly focused radially polarized beam has some unique and interesting properties. For instance the light on the optical axis in the focal volume corresponds to a null Poynting vector, indicating the light there to be nonpropagating. However, the beam here is considered to be an unaberrated one. Thus it will be important to know whether the commonly occurring monochromatic aberrations can have any effect on the ideal Poynting vector profile of a radially polarized beam. In this paper we make use of the Fourier transform form of the vectorial diffraction theory to investigate the effect of primary aberrations on the Poynting vector profile of a radially polarized beam under tight focusing conditions. We present here the results from our study on the behavior of both the time averaged and time dependent Poynting vector profiles in the focal volume.

  7. Exclusive diffractive processes in QCD

    Science.gov (United States)

    Pichowsky, M. A.; Lee, T.-S. H.

    1996-10-01

    We consider the role of nonperturbative, confined quarks in the Pomeron-exchange model of exclusive, diffractive processes. In our approach, mesons are treated as q-barq bound states and Pomeron-exchange mediates the quark-nucleon interaction. This interaction is modeled in terms of 4 parameters which are completely determined by examining π p and K p elastic scattering. The predicted ρ- and φ-meson electroproduction cross sections are in excellent agreement with the data. It is shown that the differences in the behavior of electroproduction cross sections for the different vector mesons (ρ, φ, J/ψ) arise from their quark substructures. Furthermore, several interesting features of vector meson electroproduction, recently observed at DESY, naturally arise in this approach. The model is also used to predict ρ p, φ p, ρ ρ, φ φ, and φ ρ elastic scattering cross sections necessary for investigations of QCD aspects of vector meson production from relativistic heavy ion collisions.

  8. Applying the theory of island biogeography to emerging pathogens: toward predicting the sources of future emerging zoonotic and vector-borne diseases.

    Science.gov (United States)

    Reperant, Leslie A

    2010-03-01

    Abstract Emerging infectious diseases are recognized as increasing threats to public and animal health, global economy, and social and political stability. Climate change, environmental changes, changes in human demographics and behaviors, and the rise of global trade and travel are most-often-cited drivers for the emergence of infectious diseases in human and animal populations (Schrag and Wiener 1995 , Daszak et al. 2001 , Dobson and Foufopoulos 2001 , May et al. 2001 , Taylor et al. 2001 , Antia et al. 2003 , IOM 2003 , Kuiken et al. 2003 , Weiss and McMichael 2004 , Wolfe et al. 2005 , Woolhouse and Gowtage-Sequeria 2005 , Chomel et al. 2007 , Woolhouse and Gaunt 2007 , Jones et al. 2008 ). Emerging pathogens are more likely to be zoonotic or vector-borne with a broad host range (Daszak et al. 2000 , Taylor et al. 2001 , Woolhouse and Gowtage-Sequeria 2005 , Jones et al. 2008 ). Emerging pathogens are also more frequently RNA viruses (Woolhouse and Gowtage-Sequeria 2005 ), which may better adapt to and establish in novel host species (Antia et al. 2003 , Andre and Day 2005 , Woolhouse et al. 2005 ). Determining the factors driving disease emergence eventually aims at assisting the prediction of the future emergence of infectious diseases. However, because of the multifactorial nature of the drivers involved (IOM 2003 ), our ability to predict which pathogens may arise in human or animal populations in the future remains limited (WHO/FAO/OIE 2004 ). In particular, the ability to identify the animal reservoirs where the greatest risks to human health will originate was deemed improbable (WHO/FAO/OIE 2004 ). Applying the theory of island biogeography (MacArthur and Wilson 1967 ) to emerging pathogens identifies (i) interactions between recipient host species and species sources of pathogens (including vector species), (ii) interactions within species sources of pathogens, and (iii) interactions within recipient host species, as mechanisms directly driving disease

  9. Description of diffraction-grating experiments for photons and electrons in Feynman's spacetime formulation of quantum mechanics: the quantum origins of classical wave theories of light and massive particles

    Science.gov (United States)

    Field, J. H.

    2013-11-01

    The five laws of relativistic quantum mechanics, according to Feynman's path integral formulation, are concisely stated and applied to experiments. Reflection-diffraction-grating experiments for both photons and electrons are analysed, in particular, the Davisson-Germer experiment in which the wave-like property of electrons was first established. It is shown how classical, purely spatial, effective wave theories for both photons and electrons are predicted by the path integral formulation of quantum mechanics. The standard Copenhagen interpretation of wave mechanics is critically discussed in the light of the described experimental applications of the path integral formulation.

  10. AN X-RAY-DIFFRACTION STUDY ON THE TEMPERATURE AND CHEMICAL-COMPOSITION DEPENDENCE OF THE MODULATION WAVE-VECTOR IN [(CH3)(4)N]2ZNCL4-XBRX COMPOUNDS

    NARCIS (Netherlands)

    VOGELS, LJP; MEEKES, H; DEBOER, JL

    1994-01-01

    In this paper we study the behaviour of the modulation wave vector in [(CH3)(4)N]2ZnCl4-xBrx compounds as a function of composition (x) and temperature. We compare the results of this x-ray study with those of morphological experiments. The two results are quite well correlated, showing several

  11. High-energy electron diffraction and microscopy

    CERN Document Server

    Peng, L M; Whelan, M J

    2011-01-01

    This book provides a comprehensive introduction to high energy electron diffraction and elastic and inelastic scattering of high energy electrons, with particular emphasis on applications to modern electron microscopy. Starting from a survey of fundamental phenomena, the authors introduce the most important concepts underlying modern understanding of high energy electron diffraction. Dynamical diffraction in transmission (THEED) and reflection (RHEED) geometries is treated using ageneral matrix theory, where computer programs and worked examples are provided to illustrate the concepts and to f

  12. About vectors

    CERN Document Server

    Hoffmann, Banesh

    1975-01-01

    From his unusual beginning in ""Defining a vector"" to his final comments on ""What then is a vector?"" author Banesh Hoffmann has written a book that is provocative and unconventional. In his emphasis on the unresolved issue of defining a vector, Hoffmann mixes pure and applied mathematics without using calculus. The result is a treatment that can serve as a supplement and corrective to textbooks, as well as collateral reading in all courses that deal with vectors. Major topics include vectors and the parallelogram law; algebraic notation and basic ideas; vector algebra; scalars and scalar p

  13. Vector analysis

    CERN Document Server

    Newell, Homer E

    2006-01-01

    When employed with skill and understanding, vector analysis can be a practical and powerful tool. This text develops the algebra and calculus of vectors in a manner useful to physicists and engineers. Numerous exercises (with answers) not only provide practice in manipulation but also help establish students' physical and geometric intuition in regard to vectors and vector concepts.Part I, the basic portion of the text, consists of a thorough treatment of vector algebra and the vector calculus. Part II presents the illustrative matter, demonstrating applications to kinematics, mechanics, and e

  14. Vector SIMP dark matter

    Science.gov (United States)

    Choi, Soo-Min; Hochberg, Yonit; Kuflik, Eric; Lee, Hyun Min; Mambrini, Yann; Murayama, Hitoshi; Pierre, Mathias

    2017-10-01

    Strongly Interacting Massive Particles (SIMPs) have recently been proposed as light thermal dark matter relics. Here we consider an explicit realization of the SIMP mechanism in the form of vector SIMPs arising from an SU(2) X hidden gauge theory, where the accidental custodial symmetry protects the stability of the dark matter. We propose several ways of equilibrating the dark and visible sectors in this setup. In particular, we show that a light dark Higgs portal can maintain thermal equilibrium between the two sectors, as can a massive dark vector portal with its generalized Chern-Simons couplings to the vector SIMPs, all while remaining consistent with experimental constraints.

  15. Vector Difference Calculus

    Science.gov (United States)

    Schwalm, W. A.; Schwalm, M. K.; Giona, M.

    1998-03-01

    Space is filled with triangulating graph \\calG to serve as a quadrature grid. A discrete analog of the theory of differential forms is constructed using the associated simplical complex. The role of a basis for Λ^p at a point is played by the set of (p+1) -simplices containing a given vertex. Vector difference operations analogous to div, grad and curl, together with corresponding vector identities and exact difference analogs of the Stokes-type theorems, are obtained in terms of the boundary partial and coboundary d. Difference versions of the full vector Maxwell electromagnetic equations are analyzed on a random structure.

  16. Vector correlations in rotationally inelastic molecular collisions

    Energy Technology Data Exchange (ETDEWEB)

    Lemeshko, Mikhail

    2011-04-13

    The thesis presents an analytic model that describes scalar and vector properties of molecular collisions, both field-free and in fields. The model is based on the sudden approximation and treats molecular scattering as the Fraunhofer diffraction of matter waves from the hard-core part of the interaction potential. The theory has no fitting parameters and is inherently quantum, rendering fully state- and energy-resolved scattering amplitudes and all the quantities that unfold from them in analytic form. This allows to obtain complex polarization moments inherent to quantum stereodynamics, and to account for interference and other non-classical effects. The simplicity and analyticity of the model paves a way to understanding the origin of the features observed in experiment and exact computations, such as the angular oscillations in the state-to-state differential cross sections and the polarization moments, the rotational-state dependent variation of the integral cross sections, and change of these quantities as a function of the applied field. The theory was applied to study the k - k{sup '} vector correlation (differential cross section) for the following collision systems: Ar-NO(X{sup 2}{pi}) and Ne-OCS(X{sup 1}{sigma}) in an electrostatic field, Na{sup +}-N{sub 2}(X{sup 1}{sigma}) in a laser field, and He-CaH({sup 2}{sigma}), He-O{sub 2}(X{sup 3}{sigma}), and He-OH(X{sup 2}{pi}) in a magnetic field. The model was able to reproduce the behavior of the differential cross sections and their variation with field strength. Combining the Fraunhofer model with the quantum theory of vector correlations made it possible to study three- and four-vector properties. The model results for the k-k{sup '}-j{sup '} vector correlation in Ar-NO(X{sup 2}{pi}) and He-NO(X{sup 2}{pi}) scattering were found to be in good agreement with experiment and exact computations. This allowed to demonstrate that the stereodynamics of such collisions is contained solely in the

  17. Integration of vector-valued functions with respect to vector measures defined on δ-rings

    OpenAIRE

    Chakraborty, N. D.; Basu, Santwana

    2011-01-01

    This paper extends the theory of scalar-valued integrable functions with respect to vector measures defined on δ-rings to the case of vector-valued tensor integrable functions with respect to vector measures defined on δ-rings. This paper also generalizes some results of G. F. Stefánsson for tensor integration theory of vector-valued functions with respect to vector measures defined on σ-algebras.

  18. Fresnel equations and transmission line analogues for diffraction gratings

    Energy Technology Data Exchange (ETDEWEB)

    Kaushik, S.

    1995-08-01

    A simple and intuitive formalism is presented to describe diffraction in multi-layered periodic structures. We use the well known results from scalar analysis (wave propagation in homogeneous layered media) and show that they can be generalized rather readily to vector problems such as diffraction analysis. Specifically, we derive: (1) generalized Fresnel equations appropriate for reflection and transmission from an infinitely thick grating, (2) a generalized Airy formula for thin-film to describe reflection and transmission of light through a lamellar grating and (3) a matrix propagation method akin to that used for multi-layer thin film analysis. The results developed here complement the recent work on R-matrix and S-matrix propagation algorithms that have been used in connection with modal and differential grating theories. These algorithms have proven to be numerically stable for calculating diffraction efficiencies from deep groove gratings. The formalism developed here expands upon the earlier literature by providing important details that are hitherto unavailable.

  19. PENERAPAN MODEL ARBITRAGE PRICING THEORY DENGAN PENDEKATAN VECTOR AUTOREGRESSION DALAM MENGESTIMASI EXPECTED RETURN SAHAM (Studi Kasus: Saham-Saham Kompas100 Periode 2010-2013

    Directory of Open Access Journals (Sweden)

    VIAN RISKA AYUNING TYAS

    2014-08-01

    Full Text Available The Arbitrage Pricing Theory (APT is an alternative model to estimate the price of securities based of arbitrage concept. In APT, the returns of securities are affected by several factors. This research is aimed to estimate the expected returns of securities using APT model and Vector Autoregressive model. There are ten stocks incorporated in Kompas100 index and four macroeconomic variables, these are inflation, exchange rates, the amountof circulate money (JUB, and theinterest rateof Bank Indonesia(SBI are applied in this research. The first step in using VAR is to test the stationary of the data using colerogram and the results indicate that all data are stationary. The second step is to select the optimal lag based on the smallest value of AIC. The Granger causality test shows that the LPKR stock is affected by the inflation and the exchange rate while the nine other stocks do not show the existence of the expected causality. The results of causality test are then estimated by the VAR models in order to obtain expected returnof macroeconomic factors. The expected return of macroeconomic factors obtained is used in the APT model, then the expected return stock LPKR is calculated. It shows that the expected return of LPKR is 3,340%

  20. PENERAPAN MODEL ARBITRAGE PRICING THEORY DENGAN PENDEKATAN VECTOR AUTOREGRESSION DALAM MENGESTIMASI EXPECTED RETURN SAHAM (Studi Kasus: Saham-Saham Kompas100 Periode 2010-2013

    Directory of Open Access Journals (Sweden)

    VIAN RISKA AYUNING TYAS

    2014-01-01

    Full Text Available The Arbitrage Pricing Theory (APT is an alternative model to estimate the price of securities based of arbitrage concept. In APT, the returns of securities are affected by several factors. This research is aimed to estimate the expected returns of securities using APT model and Vector Autoregressive model. There are ten stocks incorporated in Kompas100 index and four macroeconomic variables, these are inflation, exchange rates, the amountof circulate money (JUB, and theinterest rateof Bank Indonesia(SBI are applied in this research. The first step in using VAR is to test the stationary of the data using colerogram and the results indicate that all data are stationary. The second step is to select the optimal lag based on the smallest value of AIC. The Granger causality test shows that the LPKR stock is affected by the inflation and the exchange rate while the nine other stocks do not show the existence of the expected causality. The results of causality test are then estimated by the VAR models in order to obtain expected returnof macroeconomic factors. The expected return of macroeconomic factors obtained is used in the APT model, then the expected return stock LPKR is calculated. It shows that the expected return of LPKR is 3,340%

  1. Off-Shell Twist-Four Photon Light-Cone Wavefunction for the Chirality-Conserving Quark-Antiquark Vector Current in the Low-Energy Effective Theory of QCD

    Science.gov (United States)

    Li, Minghai; Liu, Jueping

    Within the framework of the low-energy effective theory arising from the instanton vacuum model of QCD, the twist-four virtual photon wavefunction, gγ3(u, P2), corresponding to the nonlocal quark-antiquark vector current is calculated at the low-energy scale. The coupling constant, fγ(P2), of the quark-antiquark vector current to the virtual photon state is also obtained. The behavior of the coupling as well as the obtained photon wave function especially at the end points is discussed.

  2. Diffractive dijet production at HERA

    CERN Document Server

    Bruni, A; Krämer, G; Schatzel, S

    2005-01-01

    We present recent experimental data from the H1 and ZEUS Collaborations at HERA for diffractive dijet production in deep-inelastic scattering (DIS) and photoproduction and compare them with next-to-leading order (NLO) QCD predictions using diffractive parton densities. While good agreement is found for DIS, the dijet photoproduction data are overestimated by the NLO theory, showing that factorization breaking occurs at this order. While this is expected theoretically for resolved photoproduction, the fact that the data are better described by a global suppression of direct and resolved contribution by about a factor of two comes as a surprise. We therefore discuss in some detail the factorization scheme and scale dependence between direct and resolved contributions and propose a new factorization scheme for diffractive dijet photoproduction.

  3. The molecular structure of gaseous dichloro(dimethylamino)phosphane, Cl 2PN(CH 3) 2, by electron diffraction and density functional theory calculations

    Science.gov (United States)

    Baskakova, Polina E.; Belyakov, Alexander V.; Haaland, Arne; Volden, Hans Vidar

    2001-06-01

    The molecular structure of the title compound has been investigated by gas electron diffraction and DFT calculations at the B3PW91/6-311+G∗ level. The equilibrium conformation is characterised by an approximately orthogonal orientation of the electron lone pars on the N and P atoms; the dihedral angle lpNPlp is 78(3)° (lp=lone pair). The configuration of the N atom is quasi-planar; the sum of the three valence angles being 356(2)°. It is suggested that the orthogonal conformation is stabilized by an anomeric effect, i.e. through delocalization of the electron lone pair on N into an antibonding σ∗(P-Cl) orbital. The P-CI bond which is anti the N lone pair is P-Cl†=2.099(3) Å, the one which is gauche P-Cl=2.056(3) Å, the valence angle NPCl†=1053(11)°, NPCl=101.8(11)°. The P-N bond distance is 1.663(4) Å.

  4. Diffraction coherence in optics

    CERN Document Server

    Françon, M; Green, L L

    2013-01-01

    Diffraction: Coherence in Optics presents a detailed account of the course on Fraunhofer diffraction phenomena, studied at the Faculty of Science in Paris. The publication first elaborates on Huygens' principle and diffraction phenomena for a monochromatic point source and diffraction by an aperture of simple form. Discussions focus on diffraction at infinity and at a finite distance, simplified expressions for the field, calculation of the path difference, diffraction by a rectangular aperture, narrow slit, and circular aperture, and distribution of luminous flux in the airy spot. The book th

  5. Sesquilinear uniform vector integral

    Indian Academy of Sciences (India)

    1Faculty of Mathematics and Computer Science, University of Bucharest, Bucharest,. Academiei Str., 14, 010014, Romania. 2Technical University of Civil ... an integral of scalar functions with respect to vector measures, Dunford and his school introduced the spectral operators, thus founding the present operator theory (see ...

  6. On the Distribution of Norm of Vector Projection and Rejection of Two Complex Normal Random Vectors

    Directory of Open Access Journals (Sweden)

    Mehdi Maleki

    2015-01-01

    Full Text Available Vector projection and vector rejection are highly common and useful operations in mathematics, information theory, and signal processing. In this paper, we find the distribution of the norm of projection and rejection vectors when the original vectors are standard complex normally distributed.

  7. Vector analysis

    CERN Document Server

    Brand, Louis

    2006-01-01

    The use of vectors not only simplifies treatments of differential geometry, mechanics, hydrodynamics, and electrodynamics, but also makes mathematical and physical concepts more tangible and easy to grasp. This text for undergraduates was designed as a short introductory course to give students the tools of vector algebra and calculus, as well as a brief glimpse into these subjects' manifold applications. The applications are developed to the extent that the uses of the potential function, both scalar and vector, are fully illustrated. Moreover, the basic postulates of vector analysis are brou

  8. Diffractive production of mesons

    Directory of Open Access Journals (Sweden)

    Schicker Rainer

    2014-01-01

    Full Text Available The interest in the study of diffractive meson production is discussed. The description of diffraction within Regge phenomenology is presented, and the QCD-based understanding of diffractive processes is given. Central production is reviewed, and the corresponding main results from the COMPASS experiment and from the experiments at the ISR, RHIC, TEVATRON and LHC collider are summarised.

  9. Scalar-vector bootstrap

    Energy Technology Data Exchange (ETDEWEB)

    Rejon-Barrera, Fernando [Institute for Theoretical Physics, University of Amsterdam,Science Park 904, Postbus 94485, 1090 GL, Amsterdam (Netherlands); Robbins, Daniel [Department of Physics, Texas A& M University,TAMU 4242, College Station, TX 77843 (United States)

    2016-01-22

    We work out all of the details required for implementation of the conformal bootstrap program applied to the four-point function of two scalars and two vectors in an abstract conformal field theory in arbitrary dimension. This includes a review of which tensor structures make appearances, a construction of the projectors onto the required mixed symmetry representations, and a computation of the conformal blocks for all possible operators which can be exchanged. These blocks are presented as differential operators acting upon the previously known scalar conformal blocks. Finally, we set up the bootstrap equations which implement crossing symmetry. Special attention is given to the case of conserved vectors, where several simplifications occur.

  10. Cloning vector

    Science.gov (United States)

    Guilfoyle, R.A.; Smith, L.M.

    1994-12-27

    A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site. 2 figures.

  11. Cloning vector

    Science.gov (United States)

    Guilfoyle, Richard A.; Smith, Lloyd M.

    1994-01-01

    A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site.

  12. Kinematic Diffraction from a Mathematical Viewpoint

    OpenAIRE

    Baake, Michael; Grimm, Uwe

    2011-01-01

    Mathematical diffraction theory is concerned with the analysis of the diffraction image of a given structure and the corresponding inverse problem of structure determination. In recent years, the understanding of systems with continuous and mixed spectra has improved considerably. Simultaneously, their relevance has grown in practice as well. In this context, the phenomenon of homometry shows various unexpected new facets. This is particularly so for systems with stochastic components. After ...

  13. Diffractive measurements in ATLAS

    CERN Document Server

    Grafstrom, P; The ATLAS collaboration

    2011-01-01

    Several diffractive measurements in ATLAS are discussed. Using a diffractive enhanced event sample, the diffractive fraction of the inelastic cross section is determined to be in the range 25-30 % dependent on what model is used. Rapidity gap studies give similar percentages. The differential cross section as a function of the rapidity gap size has been determined at the hadron level. The diffractive cross section is roughly 1 mb per unit of gap size for gap sizes bigger than 3.5 units.

  14. The biological control of disease vectors.

    Science.gov (United States)

    Okamoto, Kenichi W; Amarasekare, Priyanga

    2012-09-21

    Vector-borne diseases are common in nature and can have a large impact on humans, livestock and crops. Biological control of vectors using natural enemies or competitors can reduce vector density and hence disease transmission. However, the indirect interactions inherent in host-vector disease systems make it difficult to use traditional pest control theory to guide biological control of disease vectors. This necessitates a conceptual framework that explicitly considers a range of indirect interactions between the host-vector disease system and the vector's biological control agent. Here we conduct a comparative analysis of the efficacy of different types of biological control agents in controlling vector-borne diseases. We report three key findings. First, highly efficient predators and parasitoids of the vector prove to be effective biological control agents, but highly virulent pathogens of the vector also require a high transmission rate to be effective. Second, biocontrol agents can successfully reduce long-term host disease incidence even though they may fail to reduce long-term vector densities. Third, inundating a host-vector disease system with a natural enemy of the vector has little or no effect on reducing disease incidence, but inundating the system with a competitor of the vector has a large effect on reducing disease incidence. The comparative framework yields predictions that are useful in developing biological control strategies for vector-borne diseases. We discuss how these predictions can inform ongoing biological control efforts for host-vector disease systems. Copyright © 2012. Published by Elsevier Ltd.

  15. Helices and vector bundles

    CERN Document Server

    Rudakov, A N

    1990-01-01

    This volume is devoted to the use of helices as a method for studying exceptional vector bundles, an important and natural concept in algebraic geometry. The work arises out of a series of seminars organised in Moscow by A. N. Rudakov. The first article sets up the general machinery, and later ones explore its use in various contexts. As to be expected, the approach is concrete; the theory is considered for quadrics, ruled surfaces, K3 surfaces and P3(C).

  16. Vector geometry

    CERN Document Server

    Robinson, Gilbert de B

    2011-01-01

    This brief undergraduate-level text by a prominent Cambridge-educated mathematician explores the relationship between algebra and geometry. An elementary course in plane geometry is the sole requirement for Gilbert de B. Robinson's text, which is the result of several years of teaching and learning the most effective methods from discussions with students. Topics include lines and planes, determinants and linear equations, matrices, groups and linear transformations, and vectors and vector spaces. Additional subjects range from conics and quadrics to homogeneous coordinates and projective geom

  17. Diffraction: Principles and application

    Directory of Open Access Journals (Sweden)

    Hansen Thomas C.

    2015-01-01

    Full Text Available We introduce here diffraction in general, as well as neutron and powder diffraction in particular as a tool to study the structure of condensed matter, crystalline solids in particular. Diffraction is a crucial experimental technique of extraordinary potential to elucidate the structure and its evolution of materials important for all domains in the production, conversion, storage and transport of energy. It allows therefore establishing structure-property relationships, which need to be understood in order to develop new and better performing materials.

  18. Recent results on diffractive and forward physics at HERA

    Science.gov (United States)

    Yuji, Yamazaki

    2017-04-01

    Recent studies on diffractive processes in ep scattering at HERA are reviewed. Heavy quark production in diffractive processes was studied by tagging a D* meson in diffractive DIS events. The cross section for events with a prompt photon in the final state was also measured. The data are well reproduced by models using diffractive parton densities determined from inclusive diffractive DIS cross sections. Two studies were also made on exclusive vector meson production. The cross-section ratio σψ((2S))/σ(ψ(1S)), which reflects the difference in transverse shape of the charmonium wave functions, are compared to various models. Moreover, the diffractive ρ0 photoproduction with a forward neutron, which has two vertices with small-pT recoil, were measured to study factorisation properties. The data show some indication of re-scattering.

  19. Diffractive Measurements in ATLAS

    CERN Document Server

    Shaw, K

    2012-01-01

    Measurements made using the ATLAS detector at the LHC at \\surd s = 7 TeV incorporating diffractive processes are presented. A first measurement of the inelastic cross-section using 20 \\mu b-1 of data is given, yielding a result of {\\sigma}inel ({\\xi} > 5 \\times 10-6) = 60.3 \\pm 2.1 mb, for single (p p \\rightarrow X p) and double (p p \\rightarrow XY) diffractive processes for a kinematic range corresponding to detector acceptance {\\xi} = M2X /s calculated from the invariant mass MX of the heavier dissociation system X. Furthermore a study is made of pseudorapidity gap distributions using 7.1 \\pm 0.2 \\mu b-1 of data collected to tune the diffractive fraction of the inelastic cross-section in Monte Carlo (MC) models, and a measurement is made of the differential cross-section for events with large gaps in pseudorapidity where diffractive processes dominate.

  20. Diffraction at TOTEM

    CERN Document Server

    Giani, S; Antchev, G; Aspell, P; Avati, V; Bagliesi, M G; Berardi, V; Berretti, M; Besta, M; Bozzo, M; Brücken, E; Buzzo, A; Cafagna, F; Calicchio, M; Catanesi, M G; Cecchi, R; Ciocci, M A; Dadel, P; Deile, M; Dimovasili, E; Eggert, K; Eremin, V; Ferro, F; Fiergolski, A; García, F; Greco, V; Grzanka, L; Heino, J; Hildén, T; Kaspar, J; Kopal, J; Kundrát, V; Kurvinen, K; Lami, S; Latino, G; Lauhakangas, R; Leszko, R; Lippmaa, E; Lokajícek, M; Lo Vetere, M; Lucas Rodriguez, F; Macrí, M; Magazzù, G; Meucci, M; Minutoli, S; Notarnicola, G; Oliveri, E; Oljemark, F; Orava, R; Oriunno, M; Österberg, K; Pedreschi, E; Petäjäjärvi, J; Prochazka, J; Quinto, M; Radermacher, E; Radicioni, E; Ravotti, F; Rella, G; Robutti, E; Ropelewski, L; Rostkowski, M; Ruggiero, G; Rummel, A; Saarikko, H; Sanguinetti, G; Santroni, A; Scribano, A; Sette, G; Snoeys, W; Spinella, F; Ster, A; Taylor, C; Trummal, A; Turini, N; Whitmore, J; Wu, J; Zalewski, M

    2010-01-01

    The primary objective of the TOTEM experiment at the LHC is the measurement of the total proton-proton cross section with the luminosity-independent method and the study of elastic proton-proton cross-section over a wide |t|-range. In addition TOTEM also performs a comprehensive study of diffraction, spanning from cross-section measurements of individual diffractive processes to the analysis of their event topologies. Hard diffraction will be studied in collaboration with CMS taking advantage of the large common rapidity coverage for charged and neutral particle detection and the large variety of trigger possibilities even at large luminosities. TOTEM will take data under all LHC beam conditions including standard high luminosity runs to maximise its physics reach. This contribution describes the main features of the TOTEM diffractive physics programme including measurements to be made in the early LHC runs.

  1. Diffraction at TOTEM

    CERN Document Server

    Antchev, G.; Avati, V.; Bagliesi, M.G.; Berardi, V.; Berretti, M.; Bottigli, U.; Bozzo, M.; Brucken, E.; Buzzo, A.; Cafagna, F.; Calicchio, M.; Catanesi, M.G.; Catastini, P.L.; Cecchi, R.; Ciocci, M.A.; Deile, M.; Dimovasili, E.; Eggert, K.; Eremin, V.; Ferro, F.; Garcia, F.; Giani, S.; Greco, V.; Heino, J.; Hilden, T.; Kaspar, J.; Kopal, J.; Kundrat, V.; Kurvinen, K.; Lami, S.; Latino, G.; Lauhakangas, R.; Lippmaa, E.; Lokajicek, M.; Lo Vetere, M.; Lucas Rodriguez, F.; Macri, M.; Magazzu, G.; Meucci, M.; Minutoli, S.; Niewiadomski, H.; Noschis, E.; Notarnicola, G.; Oliveri, E.; Oljemark, F.; Orava, R.; Oriunno, M.; Osterberg, K.; Palazzi, P.; Pedreschi, E.; Petajajarvi, J.; Quinto, M.; Radermacher, E.; Radicioni, E.; Ravotti, F.; Rella, G.; Robutti, E.; Ropelewski, L.; Ruggiero, G.; Rummel, A.; Saarikko, H.; Sanguinetti, G.; Santroni, A.; Scribano, A.; Sette, G.; Snoeys, W.; Spinella, F.; Squillacioti, P.; Ster, A.; Taylor, C.; Trummal, A.; Turini, N.; Whitmore, J.; Wu, J.

    2009-01-01

    The TOTEM experiment at the LHC measures the total proton-proton cross section with the luminosity-independent method and the elastic proton-proton cross-section over a wide |t|-range. It also performs a comprehensive study of diffraction, spanning from cross-section measurements of individual diffractive processes to the analysis of their event topologies. Hard diffraction will be studied in collaboration with CMS taking advantage of the large common rapidity coverage for charged and neutral particle detection and the large variety of trigger possibilities even at large luminosities. TOTEM will take data under all LHC beam conditions including standard high luminosity runs to maximize its physics reach. This contribution describes the main features of the TOTEM physics programme including measurements to be made in the early LHC runs. In addition, a novel scheme to extend the diffractive proton acceptance for high luminosity runs by installing proton detectors at IP3 is described.

  2. Powder Diffraction: By Decades

    Science.gov (United States)

    David, William I. F.

    This introductory chapter reviews the first 100 years of powder diffraction, decade by decade, from the earliest X-ray powder diffraction measurements of the crystal structure of graphite through to the diversity and complexity of twenty-first century powder diffraction. Carbon features as an illustrative example throughout the discussion of these ten decades from graphite and the disorder of carbon black through to lonsdaleite, the elusive hexagonal polymorph of diamond, and C60, the most symmetrical of molecules. Electronics and computing have played a leading role in the development of powder diffraction, particularly over the past 60 years, and the Moore's Law decade-by-decade rise in computing power is clear in the increasing complexity of powder diffraction experiments and material systems that can be studied. The chapter concludes with a final discussion of decades - the four decades of length-scale from the ångstrom to the micron that not only represent the domain of powder diffraction but are also the distances that will dominate twenty-first century science and technology.

  3. An introduction to vectors, vector operators and vector analysis

    CERN Document Server

    Joag, Pramod S

    2016-01-01

    Ideal for undergraduate and graduate students of science and engineering, this book covers fundamental concepts of vectors and their applications in a single volume. The first unit deals with basic formulation, both conceptual and theoretical. It discusses applications of algebraic operations, Levi-Civita notation, and curvilinear coordinate systems like spherical polar and parabolic systems and structures, and analytical geometry of curves and surfaces. The second unit delves into the algebra of operators and their types and also explains the equivalence between the algebra of vector operators and the algebra of matrices. Formulation of eigen vectors and eigen values of a linear vector operator are elaborated using vector algebra. The third unit deals with vector analysis, discussing vector valued functions of a scalar variable and functions of vector argument (both scalar valued and vector valued), thus covering both the scalar vector fields and vector integration.

  4. Vector velocimeter

    DEFF Research Database (Denmark)

    2012-01-01

    for generation of a reference beam, a detector system comprising a first detector arrangement arranged in such a way that the signal beam and the reference beam are incident upon the first detector arrangement with the reference beam propagating at an angle relative to a signal beam, and wherein the first......The present invention relates to a compact, reliable and low-cost vector velocimeter for example for determining velocities of particles suspended in a gas or fluid flow, or for determining velocity, displacement, rotation, or vibration of a solid surface, the vector velocimeter comprising a laser...... assembly for emission of a measurement beam for illumination of an object in a measurement volume with coherent light whereby a signal beam emanating from the object in the measurement volume is formed in response to illumination of the object by the measurement beam, a reference beam generator...

  5. Generating and measuring non-diffracting vector Bessel beams

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2014-03-01

    Full Text Available beam, whose electric field is generalized as ( ) ( ) .1)(exp)(1)(exp)(),(    ∑ −+    − ∑ += −+ i QlirkJ i QlirkJru l rQl l rQl ϕϕϕ (3) Here Q corresponds to the azimuthal charge introduced by the q...)()(),,( 22 ϕθθϕ QrkJrkJrkJrkJrI l rQl l rQl l rQl l rQl +∑∑+   ∑+   ∑= −+−+ (4) To perform a measurement of the polarization and azimuthal components of the generated field it is evident from Eq. (3) that the field can...

  6. Generating and analyzing non-diffracting vector vortex beams

    CSIR Research Space (South Africa)

    Li, Y

    2013-08-01

    Full Text Available ] Bomzon, Z., Niv, A., Biener, G., Kleiner, V., and Hasman, E., “Nondiffracting periodically space-variant polarization beams with subwavelength gratings,” Applied Physics Letters 80(20), 3685 (2002). [16] Tervo, J. and Turunen, J., “Generation of vectorial... elements for wave front shaping in the visible domain: Switchable helical mode generation,” Applied Physics Letters 88(22), 221102 (2006). Proc. of SPIE Vol. 8843 884305-6 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/04/2014 Terms...

  7. Phase knife-edge laser Schlieren diffraction interferometry with ...

    Indian Academy of Sciences (India)

    581–589. Phase knife-edge laser Schlieren diffraction interferometry with boundary diffraction wave theory. RAJ KUMAR1, D MOHAN2, SUSHIL K KAURA1, D P CHHACHHIA1 and A K AGGARWAL1 ... contrast but also avoids the loss in phase information as it lets through light from all parts of the test object and its thin ...

  8. Scalar and vector Galileons

    Science.gov (United States)

    Rodríguez, Yeinzon; Navarro, Andrés A.

    2017-03-01

    An alternative for the construction of fundamental theories is the introduction of Galileons. These are fields whose action leads to non higher than second-order equations of motion. As this is a necessary but not sufficient condition to make the Hamiltonian bounded from below, as long as the action is not degenerate, the Galileon construction is a way to avoid pathologies both at the classical and quantum levels. Galileon actions are, therefore, of great interest in many branches of physics, specially in high energy physics and cosmology. This proceedings contribution presents the generalities of the construction of both scalar and vector Galileons following two different but complimentary routes.

  9. Periodically distributed objects with quasicrystalline diffraction pattern

    Energy Technology Data Exchange (ETDEWEB)

    Wolny, Janusz, E-mail: wolny@fis.agh.edu.pl; Strzalka, Radoslaw [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow (Poland); Kuczera, Pawel [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow (Poland); Laboratory of Crystallography, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich (Switzerland)

    2015-03-30

    It is possible to construct fully periodically distributed objects with a diffraction pattern identical to the one obtained for quasicrystals. These objects are probability distributions of distances obtained in the statistical approach to aperiodic structures distributed periodically. The diffraction patterns have been derived by using a two-mode Fourier transform—a very powerful method not used in classical crystallography. It is shown that if scaling is present in the structure, this two-mode Fourier transform can be reduced to a regular Fourier transform with appropriately rescaled scattering vectors and added phases. Detailed case studies for model sets 1D Fibonacci chain and 2D Penrose tiling are discussed. Finally, it is shown that crystalline, quasicrystalline, and approximant structures can be treated in the same way.

  10. Large N Expansion. Vector Models

    OpenAIRE

    Nissimov, Emil; Pacheva, Svetlana

    2006-01-01

    Preliminary version of a contribution to the "Quantum Field Theory. Non-Perturbative QFT" topical area of "Modern Encyclopedia of Mathematical Physics" (SELECTA), eds. Aref'eva I, and Sternheimer D, Springer (2007). Consists of two parts - "main article" (Large N Expansion. Vector Models) and a "brief article" (BPHZL Renormalization).

  11. Central Diffraction at ALICE

    CERN Document Server

    Lämsä, Jerry W

    2011-01-01

    The ALICE experiment is shown to be well suited for studies of exclusive final states from central diffractive reactions. The gluon-rich environment of the central system allows detailed QCD studies and searches for exotic meson states, such as glueballs, hybrids and new charmonium-like states. It would also provide a good testing ground for detailed studies of heavy quarkonia. Due to its central barrel performance, ALICE can accurately measure the low-mass central systems with good purity. The efficiency of the Forward Multiplicity Detector (FMD) and the Forward Shower Counter (FSC) system for detecting rapidity gaps is shown to be adequate for the proposed studies. With this detector arrangement, valuable new data can be obtained by tagging central diffractive processes.

  12. Diffraction pattern of triangular grating in the resonance domain.

    Science.gov (United States)

    Hoshino, Tetsuya; Banerjee, Saswatee; Itoh, Masahide; Yatagai, Toyohiko

    2009-03-01

    We propose a combination of ray optics and Fraunhofer multiple-slit diffraction theory for calculating the two-dimensional triangular periodic grating in the resonance domain. The peak of the envelope pattern of angular distribution of diffraction efficiency is calculated by ray optics while the peak width is calculated using Fraunhofer theory. It was clarified, using rigorous coupled-wave analysis and a nonstandard-finite-difference time-domain method, that the envelope pattern of the diffraction of the grating could be calculated easily and understood intuitively for the design of displays and lighting.

  13. SINGLE CRYSTAL NEUTRON DIFFRACTION.

    Energy Technology Data Exchange (ETDEWEB)

    KOETZLE,T.F.

    2001-03-13

    Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for information on magnetic scattering of neutrons see Unit 14.3. Instruments for single-crystal diffraction (single-crystal diffractometers or SCDs) are generally available at the major neutron scattering center facilities. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts is included in an appendix accompanying this unit.

  14. Experimental method for testing diffraction properties of reflection waveguide holograms.

    Science.gov (United States)

    Xie, Yi; Kang, Ming-Wu; Wang, Bao-Ping

    2014-07-01

    Waveguide holograms' diffraction properties include peak wavelength and diffraction efficiency, which play an important role in determining their display performance. Based on the record and reconstruction theory of reflection waveguide holograms, a novel experimental method for testing diffraction properties is introduced and analyzed in this paper, which uses a plano-convex lens optically contacted to the surface of the substrate plate of the waveguide hologram, so that the diffracted light beam can be easily detected. Then an experiment is implemented. The designed reconstruction wavelength of the test sample is 530 nm, and its diffraction efficiency is 100%. The experimental results are a peak wavelength of 527.7 nm and a diffraction efficiency of 94.1%. It is shown that the tested value corresponds well with the designed value.

  15. Vector fields on singular varieties

    CERN Document Server

    Brasselet, Jean-Paul; Suwa, Tatsuo

    2009-01-01

    Vector fields on manifolds play a major role in mathematics and other sciences. In particular, the Poincaré-Hopf index theorem gives rise to the theory of Chern classes, key manifold-invariants in geometry and topology. It is natural to ask what is the ‘good’ notion of the index of a vector field, and of Chern classes, if the underlying space becomes singular. The question has been explored by several authors resulting in various answers, starting with the pioneering work of M.-H. Schwartz and R. MacPherson. We present these notions in the framework of the obstruction theory and the Chern-Weil theory. The interplay between these two methods is one of the main features of the monograph.

  16. REFINEMENT OF INCOMMENSURATE STRUCTURES AGAINST DIFFRACTION DATA FROM A TWINNED CRYSTAL

    NARCIS (Netherlands)

    VANSMAALEN, S; PETRICEK, [No Value

    1992-01-01

    Twinning can lead to a diffraction pattern with additional reflections that are incommensurate with the reflections of a crystal with only one orientation of the structure. The integer indexing of such a diffraction pattern involves more than three reciprocal-basis vectors. Analogously, for

  17. Topological vector spaces and distributions

    CERN Document Server

    Horvath, John

    2012-01-01

    ""The most readable introduction to the theory of vector spaces available in English and possibly any other language.""-J. L. B. Cooper, MathSciNet ReviewMathematically rigorous but user-friendly, this classic treatise discusses major modern contributions to the field of topological vector spaces. The self-contained treatment includes complete proofs for all necessary results from algebra and topology. Suitable for undergraduate mathematics majors with a background in advanced calculus, this volume will also assist professional mathematicians, physicists, and engineers.The precise exposition o

  18. Powder diffraction at ALBA synchrotron

    OpenAIRE

    Aranda, Miguel A. G.

    2017-01-01

    This talk is devoted to explain the uses of powder diffraction at MSPD (material science and powder diffraction) of ALBA synchrotron light source. General characteristics of the beamline are: Station 1 - High Pressure Diffraction on powders with diamond anvil cell (DAC) and CCD detector. Microdiffraction; and Station 2 - High Resolution Powder Diffraction with Multicrystal- and Silicon-Strip detector. Energy Range: 8-50keV; Typical beam size: 4x1mm; all typical sample geometries possible: cap...

  19. Inclusive Hard Diffraction at HERA

    CERN Document Server

    Proskuryakov, Alexander

    2010-01-01

    Recent data from the H1 and ZEUS experiments on hard inclusive diffraction are discussed. Results of QCD analyses of the diffractive deep-inelastic scattering processes are reported. Predictions based on the extracted parton densities are compared to diffractive dijet measurements.

  20. 3D reconstruction of tensors and vectors

    Energy Technology Data Exchange (ETDEWEB)

    Defrise, Michel; Gullberg, Grant T.

    2005-02-17

    Here we have developed formulations for the reconstruction of 3D tensor fields from planar (Radon) and line-integral (X-ray) projections of 3D vector and tensor fields. Much of the motivation for this work is the potential application of MRI to perform diffusion tensor tomography. The goal is to develop a theory for the reconstruction of both Radon planar and X-ray or line-integral projections because of the flexibility of MRI to obtain both of these type of projections in 3D. The development presented here for the linear tensor tomography problem provides insight into the structure of the nonlinear MRI diffusion tensor inverse problem. A particular application of tensor imaging in MRI is the potential application of cardiac diffusion tensor tomography for determining in vivo cardiac fiber structure. One difficulty in the cardiac application is the motion of the heart. This presents a need for developing future theory for tensor tomography in a motion field. This means developing a better understanding of the MRI signal for diffusion processes in a deforming media. The techniques developed may allow the application of MRI tensor tomography for the study of structure of fiber tracts in the brain, atherosclerotic plaque, and spine in addition to fiber structure in the heart. However, the relations presented are also applicable to other fields in medical imaging such as diffraction tomography using ultrasound. The mathematics presented can also be extended to exponential Radon transform of tensor fields and to other geometric acquisitions such as cone beam tomography of tensor fields.

  1. Applied electromagnetic scattering theory

    CERN Document Server

    Osipov, Andrey A

    2017-01-01

    Besides classical applications (radar and stealth, antennas, microwave engineering), scattering and diffraction are enabling phenomena for some emerging research fields (artificial electromagnetic materials or metamaterials, terahertz technologies, electromagnetic aspects of nano-science). This book is a tutorial for advanced students who need to study diffraction theory. The textbook gives fundamental knowledge about scattering and diffraction of electromagnetic waves and provides some working examples of solutions for practical high-frequency scattering and diffraction problems. The book focuses on the most important diffraction effects and mechanisms influencing the scattering process and describes efficient and physically justified simulation methods - physical optics (PO) and the physical theory of diffraction (PTD) - applicable in typical remote sensing scenarios. The material is presented in a comprehensible and logical form, which relates the presented results to the basic principles of electromag...

  2. Vector wave propagation method.

    Science.gov (United States)

    Fertig, M; Brenner, K-H

    2010-04-01

    In this paper, we extend the scalar wave propagation method (WPM) to vector fields. The WPM [Appl. Opt.32, 4984 (1993)] was introduced in order to overcome the major limitations of the beam propagation method (BPM). With the WPM, the range of application can be extended from the simulation of waveguides to simulation of other optical elements like lenses, prisms and gratings. In that reference it was demonstrated that the wave propagation scheme provides valid results for propagation angles up to 85 degrees and that it is not limited to small index variations in the axis of propagation. Here, we extend the WPM to three-dimensional vectorial fields (VWPMs) by considering the polarization dependent Fresnel coefficients for transmission in each propagation step. The continuity of the electric field is maintained in all three dimensions by an enhanced propagation vector and the transfer matrix. We verify the validity of the method by transmission through a prism and by comparison with the focal distribution from vectorial Debye theory. Furthermore, a two-dimensional grating is simulated and compared with the results from three-dimensional RCWA. Especially for 3D problems, the runtime of the VWPM exhibits special advantage over the RCWA.

  3. The diffraction signatures of individual vibrational modes in polyatomic molecules

    Science.gov (United States)

    Ryu, Seol; Weber, Peter M.; Stratt, Richard M.

    2000-01-01

    Though one normally thinks of single-molecule diffraction studies as tools for eliciting molecular geometry, molecular diffraction patterns are really the Fourier transforms of complete molecular wave functions. There is thus at least the possibility of imaging the vibrational wave functions of polyatomic molecules by means of a pump-probe diffraction experiment: the pump laser could prepare a specific vibrational state and an electron or x-ray could then be diffracted off the molecule some short time later. The present paper develops the general theory of diffraction signatures for individual vibrational wave functions in polyatomic molecules and investigates the feasibility of seeing such signatures experimentally using the example of a linear triatomic molecule modeled after CS2. Although aligned molecules in specific vibrational quantum states turn out to exhibit very characteristic diffraction signatures, the signatures of the vibrational wave functions are partially washed out for the complete isotropy expected from gas phase molecules. Nonetheless, it is possible to design a diffraction experiment using a pump-dump sequence with a polarized laser beam which will select a nonisotropic sample of vibrationally excited molecules. We show that the resulting level of anisotropy should enhance the diffraction signature, helping to distinguish different vibrational components. These model calculations therefore suggest the possibility of observing the dynamics of vibrational wave packets using experimentally realizable diffraction techniques.

  4. Trade-off between diffraction efficiency and uniformity for design of binary diffractive laser beam shaper

    Science.gov (United States)

    Hsu, Ku-Hui; Lin, Hoang Yan

    2013-07-01

    The trade-off between diffraction efficiency and uniformity is studied when a binary phase-only diffractive optical element (DOE) is designed for transforming a Gaussian beam to an expanded squared uniform intensity distribution. The simulated annealing (SA) algorithm and Fresnel diffraction theory are applied in our design. Two types of cost functions are utilized in the SA algorithm, and the cases of different incident Gaussian diameters and bright-area sizes of the target patterns are studied. The mechanisms of reducing nonuniformity by the two cost functions are essentially different, and the mechanism combining nonuniformity and the intensity difference between the reconstructed and target patterns has better results. Satisfactory performance can be obtained under the trade-off between them.

  5. GAPS IN SUPPORT VECTOR OPTIMIZATION

    Energy Technology Data Exchange (ETDEWEB)

    STEINWART, INGO [Los Alamos National Laboratory; HUSH, DON [Los Alamos National Laboratory; SCOVEL, CLINT [Los Alamos National Laboratory; LIST, NICOLAS [Los Alamos National Laboratory

    2007-01-29

    We show that the stopping criteria used in many support vector machine (SVM) algorithms working on the dual can be interpreted as primal optimality bounds which in turn are known to be important for the statistical analysis of SVMs. To this end we revisit the duality theory underlying the derivation of the dual and show that in many interesting cases primal optimality bounds are the same as known dual optimality bounds.

  6. New Constraints on Light Vectors Coupled to Anomalous Currents

    Science.gov (United States)

    Dror, Jeff A.; Lasenby, Robert; Pospelov, Maxim

    2017-10-01

    We derive new constraints on light vectors coupled to standard model (SM) fermions, when the corresponding SM current is broken by the chiral anomaly. The cancellation of the anomaly by heavy fermions results, in the low-energy theory, in Wess-Zumino-type interactions between the new vector and the SM gauge bosons. These interactions are determined by the requirement that the heavy sector preserves the SM gauge groups and lead to (energy /vector mass )2 enhanced rates for processes involving the longitudinal mode of the new vector. Taking the example of a vector coupled to a vector coupled to SM baryon number, Z decays and flavor-changing neutral current meson decays via the new vector can occur with (weak scale /vector mass )2 enhanced rates. These processes place significantly stronger coupling bounds than others considered in the literature, over a wide range of vector masses.

  7. CMS results on hard diffraction

    CERN Document Server

    INSPIRE-00107098

    2013-01-01

    In these proceedings we present CMS results on hard diffraction. Diffractive dijet production in pp collisions at $\\sqrt{s}$=7 TeV is discussed. The cross section for dijet production is presented as a function of $\\tilde{\\xi}$, representing the fractional momentum loss of the scattered proton in single-diffractive events. The observation of W and Z boson production in events with a large pseudo-rapidity gap is also presented.

  8. Dynamic diffraction effects and coherent breathing oscillations in ultrafast electron diffraction in layered 1T-TaSeTe

    Directory of Open Access Journals (Sweden)

    Linlin Wei

    2017-07-01

    Full Text Available Anisotropic lattice movements due to the difference between intralayer and interlayer bonding are observed in the layered transition-metal dichalcogenide 1T-TaSeTe following femtosecond laser pulse excitation. Our ultrafast electron diffraction investigations using 4D-transmission electron microscopy (4D-TEM clearly reveal that the intensity of Bragg reflection spots often changes remarkably due to the dynamic diffraction effects and anisotropic lattice movement. Importantly, the temporal diffracted intensity from a specific crystallographic plane depends on the deviation parameter s, which is commonly used in the theoretical study of diffraction intensity. Herein, we report on lattice thermalization and structural oscillations in layered 1T-TaSeTe, analyzed by dynamic diffraction theory. Ultrafast alterations of satellite spots arising from the charge density wave in the present system are also briefly discussed.

  9. Study of optical Laue diffraction

    Science.gov (United States)

    Chakravarthy, Giridhar; Allam, Srinivasa Rao; Satyanarayana, S. V. M.; Sharan, Alok

    2014-10-01

    We present the study of the optical diffraction pattern of one and two-dimensional gratings with defects, designed using desktop pc and printed on OHP sheet using laser printer. Gratings so prepared, using novel low cost technique provides good visual aid in teaching. Diffraction pattern of the monochromatic light (632.8nm) from the grating so designed is similar to that of x-ray diffraction pattern of crystal lattice with point defects in one and two-dimensions. Here both optical and x-ray diffractions are Fraunhofer. The information about the crystalline lattice structure and the defect size can be known.

  10. Diffractive optics and nanophotonics resolution below the diffraction limit

    CERN Document Server

    Minin, Igor

    2016-01-01

    In this book the authors present several examples of techniques used to overcome the Abby diffraction limit using flat and 3D diffractive optical elements, photonic crystal lenses, photonic jets, and surface plasmon diffractive optics. The structures discussed can be used in the microwave and THz range and also as scaled models for optical frequencies. Such nano-optical microlenses can be integrated, for example, into existing semiconductor heterostructure platforms for next-generation optoelectronic applications. Chapter 1 considers flat diffractive lenses and innovative 3D radiating structures including a conical millimeter-wave Fresnel zone plate (FZP) lens proposed for subwavelength focusing. In chapter 2 the subwavelength focusing properties of diffractive photonic crystal lenses are considered and it is shown that at least three different types of photonic crystal lens are possible.  With the aim of achieving subwavelength focusing, in chapter 3 an alternative mechanism to produce photonic jets at Tera...

  11. Acoustical vector solitons in anisotropic media

    Science.gov (United States)

    Adamashvili, G. T.; Peikrishvili, M. D.; Koplatadze, R. R.

    2017-04-01

    A theory of acoustical vector solitons of self-induced transparency in anisotropic media is developed. It is shown that, in these systems, a two-component vector soliton oscillating with the difference and sum of the frequencies in the vicinity of the frequency of a carrying acoustic wave may arise. Explicit analytical expressions for the form and parameters of a nonlinear wave depending on the direction of pulse propagation are given.

  12. High-Energy X-Ray Diffraction Analysis Tool

    Energy Technology Data Exchange (ETDEWEB)

    2011-11-29

    The functionality of heRXD includes the following: distance and angular calibration and viewing flat-panel detector images used for X-ray diffraction; image (polar) rebinning or "caking"; line position fitting in powder diffraction images; image segmentation or "blob finding"; crystal orentation indesing; and lattice vector refinement. These functionalities encompass a critical set analyzing teh data for high-energy diffraction measurements that are currently performed at synchrotron sources such as the Advanced Photon Source (APS). The software design modular and open source under LGPL. The intent is to provide a common framework and graphical user interface that has the ability to utillize internal as well as external subroutines to provide various optins for performing the fuctionalities listed above. The software will initially be deployed at several national user facilities--including APS, ALS, and CHESS--and then made available for download using a hosting service such as sourceforge.

  13. VectorBase

    Data.gov (United States)

    U.S. Department of Health & Human Services — VectorBase is a Bioinformatics Resource Center for invertebrate vectors. It is one of four Bioinformatics Resource Centers funded by NIAID to provide web-based...

  14. Wave diffraction by a cosmic string

    Energy Technology Data Exchange (ETDEWEB)

    Fernández-Núñez, Isabel [Departament de Física Quàntica i Astrofísica, Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain); Institut de Ciències del Cosmos (ICCUB), Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain); Bulashenko, Oleg, E-mail: oleg.bulashenko@ub.edu [Departament de Física Quàntica i Astrofísica, Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain)

    2016-08-26

    We show that if a cosmic string exists, it may be identified through characteristic diffraction pattern in the energy spectrum of the observed signal. In particular, if the string is on the line of sight, the wave field is shown to fit the Cornu spiral. We suggest a simple procedure, based on Keller's geometrical theory of diffraction, which allows to explain wave effects in conical spacetime of a cosmic string in terms of interference of four characteristic rays. Our results are supposed to be valid for scalar massless waves, including gravitational waves, electromagnetic waves, or even sound in case of condensed matter systems with analogous topological defects. - Highlights: • Gravitational waves could help us to reveal cosmic strings – topological defects of early Universe. • Wave diffraction in conical spacetime of a cosmic string is solved analytically. • The Cornu spiral is shown to appear when the string is on the line of sight. • For a string located within our galaxy, the highest amplification would occur at a frequency range of LIGO detector.

  15. Custodial vector model

    DEFF Research Database (Denmark)

    Becciolini, Diego; Franzosi, Diogo Buarque; Foadi, Roshan

    2015-01-01

    We analyze the Large Hadron Collider (LHC) phenomenology of heavy vector resonances with a $SU(2)_L\\times SU(2)_R$ spectral global symmetry. This symmetry partially protects the electroweak S-parameter from large contributions of the vector resonances. The resulting custodial vector model spectrum...

  16. Insulated Foamy Viral Vectors

    Science.gov (United States)

    Browning, Diana L.; Collins, Casey P.; Hocum, Jonah D.; Leap, David J.; Rae, Dustin T.; Trobridge, Grant D.

    2016-01-01

    Retroviral vector-mediated gene therapy is promising, but genotoxicity has limited its use in the clinic. Genotoxicity is highly dependent on the retroviral vector used, and foamy viral (FV) vectors appear relatively safe. However, internal promoters may still potentially activate nearby genes. We developed insulated FV vectors, using four previously described insulators: a version of the well-studied chicken hypersensitivity site 4 insulator (650cHS4), two synthetic CCCTC-binding factor (CTCF)-based insulators, and an insulator based on the CCAAT box-binding transcription factor/nuclear factor I (7xCTF/NF1). We directly compared these insulators for enhancer-blocking activity, effect on FV vector titer, and fidelity of transfer to both proviral long terminal repeats. The synthetic CTCF-based insulators had the strongest insulating activity, but reduced titers significantly. The 7xCTF/NF1 insulator did not reduce titers but had weak insulating activity. The 650cHS4-insulated FV vector was identified as the overall most promising vector. Uninsulated and 650cHS4-insulated FV vectors were both significantly less genotoxic than gammaretroviral vectors. Integration sites were evaluated in cord blood CD34+ cells and the 650cHS4-insulated FV vector had fewer hotspots compared with an uninsulated FV vector. These data suggest that insulated FV vectors are promising for hematopoietic stem cell gene therapy. PMID:26715244

  17. Diffraction Accelerator Of Charged Particles

    CERN Document Server

    Alekseev, Yu K; Kosarev, A A; Poseryaev, A V; Shvedunov, V I; Vetrov, A A; Zayarniy, D A

    2004-01-01

    We present the results of theoretical and numerical analysis of the physical processes for laser linear accelerator based on two symmetric resonance diffraction gratings with double-sided accelerating field excitation. Structures parameters optimization provides π-mode field amplitude distribution in neighboring diffraction zone. The maximum energy gradient restricted by ablation processes in grating materials is estimated as 1-3 GeV/m. The numerical analyses and analytical approximation of electric and magnetic field structures are done, longitudinal and transverse electron beam dynamics in accelerating systems are considered, wake fields and focusing properties of diffraction gratings are estimated.

  18. New HERA Results on Diffraction

    Science.gov (United States)

    Levonian, S.

    2017-01-01

    Four new measurements are presented in the area of diffractive and exclusive production at HERA. Preliminary results are available for isolated photons in diffractive photoproduction from ZEUS and open charm cross section in diffractive deep-inelastic scattering (DIS) regime from H1. ZEUS Collaboration has also measured the cross-section ratio σ ψ (2 S) /σ J / ψ (1 S) in exclusive DIS using full HERA data statistics. Finally, H1 Collaboration for the first time studied exclusive ρ0 meson photoproduction associated with a leading neutron at HERA.

  19. The diffractive achromat full spectrum computational imaging with diffractive optics

    KAUST Repository

    Peng, Yifan

    2016-07-11

    Diffractive optical elements (DOEs) have recently drawn great attention in computational imaging because they can drastically reduce the size and weight of imaging devices compared to their refractive counterparts. However, the inherent strong dispersion is a tremendous obstacle that limits the use of DOEs in full spectrum imaging, causing unacceptable loss of color fidelity in the images. In particular, metamerism introduces a data dependency in the image blur, which has been neglected in computational imaging methods so far. We introduce both a diffractive achromat based on computational optimization, as well as a corresponding algorithm for correction of residual aberrations. Using this approach, we demonstrate high fidelity color diffractive-only imaging over the full visible spectrum. In the optical design, the height profile of a diffractive lens is optimized to balance the focusing contributions of different wavelengths for a specific focal length. The spectral point spread functions (PSFs) become nearly identical to each other, creating approximately spectrally invariant blur kernels. This property guarantees good color preservation in the captured image and facilitates the correction of residual aberrations in our fast two-step deconvolution without additional color priors. We demonstrate our design of diffractive achromat on a 0.5mm ultrathin substrate by photolithography techniques. Experimental results show that our achromatic diffractive lens produces high color fidelity and better image quality in the full visible spectrum. © 2016 ACM.

  20. Nuclear dynamical diffraction using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Dennis Eugene [Stanford Univ., CA (United States)

    1993-05-01

    The scattering of synchrotron radiation by nuclei is extensively explored in this thesis. From the multipole electric field expansion resulting from time-dependent nonrelativistic perturbation theory, a dynamical scattering theory is constructed. This theory is shown, in the many particle limit, to be equivalent to the semi-classical approach where a quantum mechanical scattering amplitude is used in the Maxwell inhomogeneous wave equation. The Moessbauer specimen whose low-lying energy levels were probed is a ferromagnetic lattice of 57Fe embedded in a yttrium iron garnet (YIG) crystal matrix. The hyperfine fields in YIG thin films were studied at low and room temperature using time-resolved quantum beat spectroscopy. Nuclear hyperfine structure quantum beats were measured using a fast plastic scintillator coincidence photodetector and associated electronics having a time resolution of 2.5 nsec. The variation of the quantum beat patterns near the Bragg [0 0 2] diffraction peak gave a Lamb-Moessbauer factor of 8.2±0.4. Exploring characteristic dynamical features in the higher order YIG [0 0 10] reflection revealed that one of the YIG crystals had bifurcated into two different layers. The dynamics of nuclear superradiance was explored. This phenomenon includes the radiative speedup exhibited by a collective state of particles, and, in striking concurrence, resonance frequency shifts. A speedup of a factor of 4 in the total decay rate and a beat frequency shift of 11/2 natural resonance linewidths were observed. Nuclear resonance scattering was also found to be a useful way of performing angular interferometry experiments, and it was used to observe the phase shift of a rotated quantum state. On the whole, nuclear dynamical diffraction theory has superbly explained many of the fascinating features of resonant magnetic dipole radiation scattered by a lattice of nuclei.

  1. Vector Galileon and inflationary magnetogenesis

    Science.gov (United States)

    Nandi, Debottam; Shankaranarayanan, S.

    2018-01-01

    Cosmological inflation provides the initial conditions for the structure formation. However, the origin of large-scale magnetic fields can not be addressed in this framework. The key issue for this long-standing problem is the conformal invariance of the electromagnetic (EM) field in 4-D. While many approaches have been proposed in the literature for breaking conformal invariance of the EM action, here, we provide a completely new way of looking at the modifications to the EM action and generation of primordial magnetic fields during inflation. We explicitly construct a higher derivative EM action that breaks conformal invariance by demanding three conditions—theory be described by vector potential Aμ and its derivatives, Gauge invariance be satisfied, and equations of motion be linear in second derivatives of vector potential. The unique feature of our model is that appreciable magnetic fields are generated at small wavelengths while tiny magnetic fields are generated at large wavelengths that are consistent with current observations.

  2. Macro motion vector quantization

    Science.gov (United States)

    Lee, Yoon Y.; Woods, John W.

    1995-04-01

    A new algorithm is developed for reducing the bit rate required for motion vectors. This algorithm is a generalization of block matching motion estimation in which the search region is represented as a codebook of motion vectors. The new algorithm, called macro motion vector quantization (MMVQ), generalized our earlier MVQ by coding a group of motion vectors. The codebook is a set of macro motion vectors which represent the block locations of the small neighboring blocks in the previous frame. We develop an interative design algorithm for the codebook. Our experiments show that the variances of displaced frame differences (DFDs) are reduced significantly compared to block matching algorithm (BMA) with the macroblock size.

  3. Diffracting the rays of technoscience: a situated critique of representation.

    Science.gov (United States)

    Timeto, Federica

    2011-12-01

    This essay focuses on the possibility of adopting a representational approach for technoscience, in which representation is considered as a situated process of dynamic "intra-action" (Barad 2007). Re-elaborating the recent critiques of representationalism (Thrift 2008), my analysis begins by analysing Hayles's situated model of representation from an early essay where she explains her definition of constrained constructivism (Hayles [1991] 1997). The essay then discusses the notions of figuration and diffraction and the way they are employed by Haraway in many of her writings for her critique of technoscience (Haraway 1991, 1997). Finally, after considering diffraction through Barad's reading of this practice in the context of her theory of agential realism (2007), it shows the links that relate constrained constructivism, situated knowledge and agential realism, and the way all of them work at "diffract[ing] the rays of technoscience" (Haraway 1997: 16) through an alternative representational practice.

  4. Femtosecond single-electron diffraction.

    Science.gov (United States)

    Lahme, S; Kealhofer, C; Krausz, F; Baum, P

    2014-05-01

    Ultrafast electron diffraction allows the tracking of atomic motion in real time, but space charge effects within dense electron packets are a problem for temporal resolution. Here, we report on time-resolved pump-probe diffraction using femtosecond single-electron pulses that are free from intra-pulse Coulomb interactions over the entire trajectory from the source to the detector. Sufficient average electron current is achieved at repetition rates of hundreds of kHz. Thermal load on the sample is avoided by minimizing the pump-probe area and by maximizing heat diffusion. Time-resolved diffraction from fibrous graphite polycrystals reveals coherent acoustic phonons in a nanometer-thick grain ensemble with a signal-to-noise level comparable to conventional multi-electron experiments. These results demonstrate the feasibility of pump-probe diffraction in the single-electron regime, where simulations indicate compressibility of the pulses down to few-femtosecond and attosecond duration.

  5. Femtosecond single-electron diffraction

    Directory of Open Access Journals (Sweden)

    S. Lahme

    2014-05-01

    Full Text Available Ultrafast electron diffraction allows the tracking of atomic motion in real time, but space charge effects within dense electron packets are a problem for temporal resolution. Here, we report on time-resolved pump-probe diffraction using femtosecond single-electron pulses that are free from intra-pulse Coulomb interactions over the entire trajectory from the source to the detector. Sufficient average electron current is achieved at repetition rates of hundreds of kHz. Thermal load on the sample is avoided by minimizing the pump-probe area and by maximizing heat diffusion. Time-resolved diffraction from fibrous graphite polycrystals reveals coherent acoustic phonons in a nanometer-thick grain ensemble with a signal-to-noise level comparable to conventional multi-electron experiments. These results demonstrate the feasibility of pump-probe diffraction in the single-electron regime, where simulations indicate compressibility of the pulses down to few-femtosecond and attosecond duration.

  6. Zinc (tris) thiourea sulphate (ZTS): A single crystal neutron diffraction ...

    Indian Academy of Sciences (India)

    tal which is used for electro-optical (EO) applications and frequency doubling of near IR laser radiations. In this study, the crystal structure of ZTS has been ob- tained in detail by single crystal neutron diffraction technique. Using the structural parameters and an existing formalism [1] based on the theory of bond polarizability,.

  7. Diffraction efficiency analysis for multi-level diffractive optical elements

    Energy Technology Data Exchange (ETDEWEB)

    Erteza, I.A.

    1995-11-01

    Passive optical components can be broken down into two main groups: Refractive elements and diffractive elements. With recent advances in manufacturing technologies, diffractive optical elements are becoming increasingly more prevalent in optical systems. It is therefore important to be able to understand and model the behavior of these elements. In this report, we present a thorough analysis of a completely general diffractive optical element (DOE). The main goal of the analysis is to understand the diffraction efficiency and power distribution of the various modes affected by the DOE. This is critical to understanding cross talk and power issues when these elements are used in actual systems. As mentioned, the model is based on a completely general scenario for a DOE. This allows the user to specify the details to model a wide variety of diffractive elements. The analysis is implemented straightforwardly in Mathematica. This report includes the development of the analysis, the Mathematica implementation of the model and several examples using the Mathematical analysis tool. It is intended that this tool be a building block for more specialized analyses.

  8. A vector space approach to geometry

    CERN Document Server

    Hausner, Melvin

    2010-01-01

    The effects of geometry and linear algebra on each other receive close attention in this examination of geometry's correlation with other branches of math and science. In-depth discussions include a review of systematic geometric motivations in vector space theory and matrix theory; the use of the center of mass in geometry, with an introduction to barycentric coordinates; axiomatic development of determinants in a chapter dealing with area and volume; and a careful consideration of the particle problem. 1965 edition.

  9. Sensorless vector and direct torque control

    CERN Document Server

    Vas, Peter

    1998-01-01

    This is the first comprehensive book on sensorless high performance a.c. drives. It is essential reading for anyone interested in acquiring a solid background on sensorless torque-controlled drives. It presents a detailed and unified treatment of sensorless vector-controlled and direct-torque controlled drive systems. It also discusses the applications of artificial intelligence to drives. Where possible, space vector theory is used and emphasis is laid on detailed mathematical and physical analysis. Sensorless drive schemes for different types of permanent magnet synchronous motors, synchronous reluctance motors, and induction motors are also presented. These include more than twenty vector drives e.g. five types of MRAS-based vector drives, and eleven types of direct-torque-controlled (DTC) drives, e.g. the ABB DTC drive. However, torque-controlled switched reluctance motor drives are also discussed due to their emerging importance. The book also covers various drive applications using artificial intellige...

  10. Application of Vector Triggering Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Ibrahim, S. R.; Brincker, Rune

    1997-01-01

    result is a Random Decrement function from each measurement. In traditional Random Decrement estimation the triggering condition is a scalar condition, which should only be fulfilled in a single measurement. In vector triggering Random Decrement the triggering condition is a vector condition....... The advantage of this new approach should be a reduction in estimation time without a significant loss of accuracy, since the vector triggering conditions ensure cross information between the measurements in the Random Decrement functions. The different problems with this technique is highlighted in two......This paper deals with applications of the vector triggering Random Decrement technique. This technique is new and developed with the aim of minimizing estimation time and identification errors. The theory behind the technique is discussed in an accompanying paper. The results presented...

  11. Application of Vector Triggering Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Ibrahim, S. R.; Brincker, Rune

    result is a Random Decrement function from each measurement. In traditional Random Decrement estimation the triggering condition is a scalar condition, which should only be fulfilled in a single measurement. In vector triggering Random Decrement the triggering condition is a vector condition....... The advantage of this new approach should be a reduction in estimation time without a significant loss of accuracy, since the vector triggering conditions ensure cross information between the measurements in the Random Decrement functions. The different problems with this technique is highlighted in two......This paper deals with applications of the vector triggering Random Decrement technique. This technique is new and developed with the aim of minimizing estimation time and identification errors. The theory behind the technique is discussed in an accompanying paper. The results presented...

  12. Dispersive approach to QCD: τ lepton hadronic decay in vector and axial-vector channels

    Science.gov (United States)

    Nesterenko, A. V.

    2015-01-01

    The dispersive approach to QCD, which extends the applicability range of perturbation theory towards the infrared domain, is developed. This approach properly accounts for the intrinsically nonperturbative constraints, which originate in the low-energy kinematic restrictions on pertinent strong interaction processes. The dispersive approach proves to be capable of describing OPAL (update 2012) and ALEPH (update 2014) experimental data on inclusive τ lepton hadronic decay in vector and axial-vector channels in a self-consistent way.

  13. Isometric Reflection Vectors and Characterizations of Hilbert Spaces

    Directory of Open Access Journals (Sweden)

    Donghai Ji

    2014-01-01

    Full Text Available A known characterization of Hilbert spaces via isometric reflection vectors is based on the following implication: if the set of isometric reflection vectors in the unit sphere SX of a Banach space X has nonempty interior in SX, then X is a Hilbert space. Applying a recent result based on well-known theorem of Kronecker from number theory, we improve this by substantial reduction of the set of isometric reflection vectors needed in the hypothesis.

  14. Polynomial Vector Fields in One Complex Variable

    DEFF Research Database (Denmark)

    Branner, Bodil

    In recent years Adrien Douady was interested in polynomial vector fields, both in relation to iteration theory and as a topic on their own. This talk is based on his work with Pierrette Sentenac, work of Xavier Buff and Tan Lei, and my own joint work with Kealey Dias....

  15. Implicit Real Vector Automata

    Directory of Open Access Journals (Sweden)

    Jean-François Degbomont

    2010-10-01

    Full Text Available This paper addresses the symbolic representation of non-convex real polyhedra, i.e., sets of real vectors satisfying arbitrary Boolean combinations of linear constraints. We develop an original data structure for representing such sets, based on an implicit and concise encoding of a known structure, the Real Vector Automaton. The resulting formalism provides a canonical representation of polyhedra, is closed under Boolean operators, and admits an efficient decision procedure for testing the membership of a vector.

  16. Non-coaxial superposition of vector vortex beams.

    Science.gov (United States)

    Aadhi, A; Vaity, Pravin; Chithrabhanu, P; Reddy, Salla Gangi; Prabakar, Shashi; Singh, R P

    2016-02-10

    Vector vortex beams are classified into four types depending upon spatial variation in their polarization vector. We have generated all four of these types of vector vortex beams by using a modified polarization Sagnac interferometer with a vortex lens. Further, we have studied the non-coaxial superposition of two vector vortex beams. It is observed that the superposition of two vector vortex beams with same polarization singularity leads to a beam with another kind of polarization singularity in their interaction region. The results may be of importance in ultrahigh security of the polarization-encrypted data that utilizes vector vortex beams and multiple optical trapping with non-coaxial superposition of vector vortex beams. We verified our experimental results with theory.

  17. Vectors and their applications

    CERN Document Server

    Pettofrezzo, Anthony J

    2005-01-01

    Geared toward undergraduate students, this text illustrates the use of vectors as a mathematical tool in plane synthetic geometry, plane and spherical trigonometry, and analytic geometry of two- and three-dimensional space. Its rigorous development includes a complete treatment of the algebra of vectors in the first two chapters.Among the text's outstanding features are numbered definitions and theorems in the development of vector algebra, which appear in italics for easy reference. Most of the theorems include proofs, and coordinate position vectors receive an in-depth treatment. Key concept

  18. Wavefront aberrations of x-ray dynamical diffraction beams.

    Science.gov (United States)

    Liao, Keliang; Hong, Youli; Sheng, Weifan

    2014-10-01

    The effects of dynamical diffraction in x-ray diffractive optics with large numerical aperture render the wavefront aberrations difficult to describe using the aberration polynomials, yet knowledge of them plays an important role in a vast variety of scientific problems ranging from optical testing to adaptive optics. Although the diffraction theory of optical aberrations was established decades ago, its application in the area of x-ray dynamical diffraction theory (DDT) is still lacking. Here, we conduct a theoretical study on the aberration properties of x-ray dynamical diffraction beams. By treating the modulus of the complex envelope as the amplitude weight function in the orthogonalization procedure, we generalize the nonrecursive matrix method for the determination of orthonormal aberration polynomials, wherein Zernike DDT and Legendre DDT polynomials are proposed. As an example, we investigate the aberration evolution inside a tilted multilayer Laue lens. The corresponding Legendre DDT polynomials are obtained numerically, which represent balanced aberrations yielding minimum variance of the classical aberrations of an anamorphic optical system. The balancing of classical aberrations and their standard deviations are discussed. We also present the Strehl ratio of the primary and secondary balanced aberrations.

  19. Counting Subspaces of a Finite Vector Space – 2

    Indian Academy of Sciences (India)

    Counting Subspaces of a Finite Vector Space – 2. Amritanshu Prasad. Keywords. Gaussian binomial coefficients, finite vector spaces. Amritanshu Prasad has been at the Institute of. Mathematical Sciences,. Chennai since 2003. His mathematical interests include representation theory, harmonic analysis, and combinatorics ...

  20. Symposium on Singularities, Representation of Algebras, and Vector Bundles

    CERN Document Server

    Trautmann, Günther

    1987-01-01

    It is well known that there are close relations between classes of singularities and representation theory via the McKay correspondence and between representation theory and vector bundles on projective spaces via the Bernstein-Gelfand-Gelfand construction. These relations however cannot be considered to be either completely understood or fully exploited. These proceedings document recent developments in the area. The questions and methods of representation theory have applications to singularities and to vector bundles. Representation theory itself, which had primarily developed its methods for Artinian algebras, starts to investigate algebras of higher dimension partly because of these applications. Future research in representation theory may be spurred by the classification of singularities and the highly developed theory of moduli for vector bundles. The volume contains 3 survey articles on the 3 main topics mentioned, stressing their interrelationships, as well as original research papers.

  1. Non-existence of limit cycles for planar vector fields

    Directory of Open Access Journals (Sweden)

    Jaume Gine

    2014-03-01

    Full Text Available This article presents sufficient conditions for the non-existence of limit cycles for planar vector fields. Classical methods for the nonexistence of limit cycles are connected with the theory developed here.

  2. Vectorization, parallelization and porting of nuclear codes. Vectorization and parallelization. Progress report fiscal 1999

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, Masaaki; Ogasawara, Shinobu; Kume, Etsuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ishizuki, Shigeru; Nemoto, Toshiyuki; Kawasaki, Nobuo; Kawai, Wataru [Fujitsu Ltd., Tokyo (Japan); Yatake, Yo-ichi [Hitachi Ltd., Tokyo (Japan)

    2001-02-01

    Several computer codes in the nuclear field have been vectorized, parallelized and trans-ported on the FUJITSU VPP500 system, the AP3000 system, the SX-4 system and the Paragon system at Center for Promotion of Computational Science and Engineering in Japan Atomic Energy Research Institute. We dealt with 18 codes in fiscal 1999. These results are reported in 3 parts, i.e., the vectorization and the parallelization part on vector processors, the parallelization part on scalar processors and the porting part. In this report, we describe the vectorization and parallelization on vector processors. In this vectorization and parallelization on vector processors part, the vectorization of Relativistic Molecular Orbital Calculation code RSCAT, a microscopic transport code for high energy nuclear collisions code JAM, three-dimensional non-steady thermal-fluid analysis code STREAM, Relativistic Density Functional Theory code RDFT and High Speed Three-Dimensional Nodal Diffusion code MOSRA-Light on the VPP500 system and the SX-4 system are described. (author)

  3. Ultrafast X-ray diffraction of laser-irradiated crystals

    CERN Document Server

    Heimann, P A; Kang, I; Johnson, S; Missalla, T; Chang, Z; Falcone, R W; Schönlein, R W; Glover, T E; Padmore, H A

    2001-01-01

    Coherent acoustic phonons have been observed in the X-ray diffraction of a laser-excited InSb crystal. Modeling based on time-dependent dynamical diffraction theory has allowed the extraction of fundamental constants, such as the electron-acoustic phonon coupling time. A dedicated beamline for time-resolved studies has been developed at the Advanced Light Source with special considerations toward high transmission, low scattering and a wide photon energy range. The facility combines a bend magnet beamline, time-resolved detectors and a femtosecond laser system.

  4. On the polarization behavior of diffraction by small elliptic aperture

    Science.gov (United States)

    Yang, Ken; Xie, Xiangsheng

    2018-01-01

    A theory on the diffraction of an elliptic Bethe-Bouwkamp aperture illuminated by a polarized plane-wave is established. The fictitious surface magnetic densities of charges and currents are rigorously represented by rewriting Bouwkamp's partial differential equations into vectorial expressions, and hence the electromagnetic field is described in a compact form. The polarization behaviors of both near-field diffraction and far-field radiation with respect to the incident light field are discussed. Novel phenomena owing to the geometry of elliptic aperture are demonstrated.

  5. Vector mesons in matter

    Indian Academy of Sciences (India)

    One consequence of the chiral restoration is the mixing of parity partners. We look for a possible signature of the mixing of vector and axial vector mesons in heavy-ion collisions. We suggest an experimental method for its observation. The dynamical evolution of the heavy-ion collision is described by a transport equation of ...

  6. Vector mesons in matter

    Indian Academy of Sciences (India)

    kfki.hu. Abstract. One consequence of the chiral restoration is the mixing of parity partners. We look for a possible signature of the mixing of vector and axial vector mesons in heavy- ion collisions. We suggest an experimental method for its ...

  7. Comparative study of different Schlieren diffracting elements

    Indian Academy of Sciences (India)

    Abstract. This paper presents an analysis of diffraction effects taking place at differ- ent Schlieren diffracting elements. Two types of diffraction effects are prominent in the. Schlieren schemes. One is diffraction of direct light (source image) at the Schlieren ele- ment, which limits the sensitivity and resolution of Schlieren ...

  8. A QCD analysis of ZEUS diffractive data

    Energy Technology Data Exchange (ETDEWEB)

    Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

    2009-11-15

    ZEUS inclusive diffractive cross-section measurements have been used in a DGLAP next-to-leading-order QCD analysis to extract the diffractive parton distribution functions. Data on diffractive dijet production in deep inelastic scattering have also been included to constrain the gluon density. Predictions based on the extracted parton densities are compared to diffractive charm and dijet photoproduction data. (orig.)

  9. Probing hard diffraction with CMS

    CERN Document Server

    Vilela Pereira, Antonio

    2012-01-01

    The cross section for dijet production in pp collisions at $\\sqrt{s} = 7$~TeV is presented as a function of $\\tilde{\\xi}$, a variable that approximates the fractional momentum loss of the scattered proton in single-diffractive events. The observation of $W$ and $Z$ boson production with a pseudo-rapidity gap in the final state is also presented.

  10. 3D -Ray Diffraction Microscopy

    DEFF Research Database (Denmark)

    Poulsen, Henning Friis; Schmidt, Søren; Juul Jensen, Dorte

    2014-01-01

    Three-dimensional X-ray diffraction (3DXRD) microscopy is a fast and non-destructive structural characterization technique aimed at the study of individual crystalline elements (grains or subgrains) within mm-sized polycrystalline specimens. It is based on two principles: the use of highly...

  11. Phonons from neutron powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrov, D.A.; Louca, D.; Roeder, H. (Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States))

    1999-09-01

    The spherically averaged structure function S([vert bar][bold q][vert bar]) obtained from pulsed neutron powder diffraction contains both elastic and inelastic scattering via an integral over energy. The Fourier transformation of S([vert bar][bold q][vert bar]) to real space, as is done in the pair density function (PDF) analysis, regularizes the data, i.e., it accentuates the diffuse scattering. We present a technique which enables the extraction of off-center ([vert bar][bold q][vert bar][ne]0) phonon information from powder diffraction experiments by comparing the experimental PDF with theoretical calculations based on standard interatomic potentials and the crystal symmetry. This procedure [dynamics from powder diffraction] has been [ital successfully] implemented as demonstrated here for two systems, a simple metal fcc Ni and an ionic crystal CaF[sub 2]. Although computationally intensive, this data analysis allows for a phonon based modeling of the PDF, and additionally provides off-center phonon information from neutron powder diffraction. [copyright] [ital 1999] [ital The American Physical Society

  12. Diffraction at a Straight Edge

    Indian Academy of Sciences (India)

    IAS Admin

    teaching and understanding physics. The simplest problem in diffraction – light pass- ing a straight edge – did not receive a rigorous solution till Sommerfeld's .... the English and. French nations. Around the same time, Young in England gave a dif- ferent formulation in which the original wave falling on the screen travels ...

  13. Imaging properties of diffraction gratings

    NARCIS (Netherlands)

    Werner, W.

    1970-01-01

    For almost a century now diffraction gratings are being used as the dispersing element in spectroscopic systems. In the greater majority of cases this grating is of the reflecting type, which (among others) has the advantage that the radiation to be analysed need not pass absorbing material as is

  14. Microarcsecond relative astrometry from the ground with a diffractive pupil

    Energy Technology Data Exchange (ETDEWEB)

    Ammons, S M; Bendek, E; Guyon, O

    2011-09-08

    The practical use of astrometry to detect exoplanets via the reflex motion of the parent star depends critically on the elimination of systematic floors in imaging systems. In the diffractive pupil technique proposed for space-based detection of exo-earths, extended diffraction spikes generated by a dotted primary mirror are referenced against a wide-field grid of background stars to calibrate changing optical distortion and achieve microarcsecond astrometric precision on bright targets (Guyon et al. 2010). We describe applications of this concept to ground-based uncrowded astrometry using a diffractive, monopupil telescope and a wide-field camera to image as many as {approx}4000 background reference stars. Final relative astrometric precision is limited by differential tip/tilt jitter caused by high altitude layers of turbulence. A diffractive 3-meter telescope is capable of reaching {approx}35 {micro}as relative astrometric error per coordinate perpendicular to the zenith vector in three hours on a bright target star (I < 10) in fields of moderate stellar density ({approx}40 stars arcmin{sup -2} with I < 23). Smaller diffractive apertures (D < 1 m) can achieve 100-200 {micro}as performance with the same stellar density and exposure time and a large telescope (6.5-10 m) could achieve as low as 10 {micro}as, nearly an order of magnitude better than current space-based facilities. The diffractive pupil enables the use of larger fields of view through calibration of changing optical distortion as well as brighter target stars (V < 6) by preventing star saturation. Permitting the sky to naturally roll to average signals over many thousands of pixels can mitigate the effects of detector imperfections.

  15. Topological vector spaces and their applications

    CERN Document Server

    Bogachev, V I

    2017-01-01

    This book gives a compact exposition of the fundamentals of the theory of locally convex topological vector spaces. Furthermore it contains a survey of the most important results of a more subtle nature, which cannot be regarded as basic, but knowledge which is useful for understanding applications. Finally, the book explores some of such applications connected with differential calculus and measure theory in infinite-dimensional spaces. These applications are a central aspect of the book, which is why it is different from the wide range of existing texts on topological vector spaces. In addition, this book develops differential and integral calculus on infinite-dimensional locally convex spaces by using methods and techniques of the theory of locally convex spaces. The target readership includes mathematicians and physicists whose research is related to infinite-dimensional analysis.

  16. Structure of amorphous selenium studied by neutron diffraction

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Knudsen, Torben Steen; Carneiro, K.

    1975-01-01

    Neutron diffraction measurements on amorphous selenium have been performed at 293 and 80 K. Careful analyses of the instrumental corrections were made to avoid systematic errors in the measured structure factor S (kappa) in the wave vector region 0 ? kappa ? 12 Å−1. As a result of the data...... treatment, the neutron scattering cross sections of selenium are determined to be sigmacoh = 8.4±0.1 b and sigmainc = 0.1±0.1 b. Using the fact that S (kappa) for large kappa's is determined by the short distances in the sample, a new method for extrapolation of the experimental S (kappa) until convergence....... Finally, we give a brief discussion of the different models for the structure of amorphous selenium, taking both diffraction measurements and thermodynamic considerations into account. The Journal of Chemical Physics is copyrighted by The American Institute of Physics....

  17. Neutron diffraction study of the magnetic structure of HoCu2

    DEFF Research Database (Denmark)

    Smetana, Z.; Sima, V.; Lebech, Bente

    1986-01-01

    Neutron diffraction measurements show that in the temperature range from 7.4 to TN=10.4 K the magnetic structure of HoCu2 is a commensurably modulated a-axis collinear structure with a wave vector q1=1/3a*. Below 7.4 K an additional structure component develops and the low temperature magnetic...

  18. Neutron Diffraction Studies of Dilute Cr-Re Single Crystal Alloys

    DEFF Research Database (Denmark)

    Lebech, Bente; Mikke, K.

    1972-01-01

    Neutron diffraction studies have been performed on five Cr-Re single crystal alloys with a Re content from 0 to 0·8 at. %. It was found that the wave vector of the sinusoidally modulated spin arrangement increases uniformly with temperature and concentration until a critical value of about 0·97. (2...

  19. Vector Integration and Stochastic Integration in Banach Spaces

    CERN Document Server

    Dinculeanu, Nicolae

    2000-01-01

    A breakthrough approach to the theory and applications of stochastic integration The theory of stochastic integration has become an intensely studied topic in recent years, owing to its extraordinarily successful application to financial mathematics, stochastic differential equations, and more. This book features a new measure theoretic approach to stochastic integration, opening up the field for researchers in measure and integration theory, functional analysis, probability theory, and stochastic processes. World-famous expert on vector and stochastic integration in Banach spaces Nicolae Dinc

  20. Vector Fields and Flows on Differentiable Stacks

    DEFF Research Database (Denmark)

    A. Hepworth, Richard

    2009-01-01

    and uniqueness of flows on a manifold as well as the author's existing results for orbifolds. It sets the scene for a discussion of Morse Theory on a general proper stack and also paves the way for the categorification of other key aspects of differential geometry such as the tangent bundle and the Lie algebra......This paper introduces the notions of vector field and flow on a general differentiable stack. Our main theorem states that the flow of a vector field on a compact proper differentiable stack exists and is unique up to a uniquely determined 2-cell. This extends the usual result on the existence...

  1. Optical properties of X-rays--dynamical diffraction.

    Science.gov (United States)

    Authier, André

    2012-01-01

    The first attempts at measuring the optical properties of X-rays such as refraction, reflection and diffraction are described. The main ideas forming the basis of Ewald's thesis in 1912 are then summarized. The first extension of Ewald's thesis to the X-ray case is the introduction of the reciprocal lattice. In the next step, the principles of the three versions of the dynamical theory of diffraction, by Darwin, Ewald and Laue, are given. It is shown how the comparison of the dynamical and geometrical theories of diffraction led Darwin to propose his extinction theory. The main optical properties of X-ray wavefields at the Bragg incidence are then reviewed: Pendellösung, shift of the Bragg peak, fine structure of Kossel lines, standing waves, anomalous absorption, paths of wavefields inside the crystal, Borrmann fan and double refraction. Lastly, some of the modern applications of the dynamical theory are briefly outlined: X-ray topography, location of adsorbed atoms at crystal surfaces, optical devices for synchrotron radiation and X-ray interferometry.

  2. Elastoplasticity theory

    CERN Document Server

    Hashiguchi, Koichi

    2014-01-01

    This book was written to serve as the standard textbook of elastoplasticity for students, engineers and researchers in the field of applied mechanics. The present second edition is improved thoroughly from the first edition by selecting the standard theories from various formulations and models, which are required to study the essentials of elastoplasticity steadily and effectively and will remain universally in the history of elastoplasticity. It opens with an explanation of vector-tensor analysis and continuum mechanics as a foundation to study elastoplasticity theory, extending over various strain and stress tensors and their rates. Subsequently, constitutive equations of elastoplastic and viscoplastic deformations for monotonic, cyclic and non-proportional loading behavior in a general rate and their applications to metals and soils are described in detail, and constitutive equations of friction behavior between solids and its application to the prediction of stick-slip phenomena are delineated. In additi...

  3. Operator theory

    CERN Document Server

    2015-01-01

    A one-sentence definition of operator theory could be: The study of (linear) continuous operations between topological vector spaces, these being in general (but not exclusively) Fréchet, Banach, or Hilbert spaces (or their duals). Operator theory is thus a very wide field, with numerous facets, both applied and theoretical. There are deep connections with complex analysis, functional analysis, mathematical physics, and electrical engineering, to name a few. Fascinating new applications and directions regularly appear, such as operator spaces, free probability, and applications to Clifford analysis. In our choice of the sections, we tried to reflect this diversity. This is a dynamic ongoing project, and more sections are planned, to complete the picture. We hope you enjoy the reading, and profit from this endeavor.

  4. Emergence and Prevalence of Human Vector-Borne Diseases in Sink Vector Populations

    Science.gov (United States)

    Rascalou, Guilhem; Pontier, Dominique; Menu, Frédéric; Gourbière, Sébastien

    2012-01-01

    Vector-borne diseases represent a major public health concern in most tropical and subtropical areas, and an emerging threat for more developed countries. Our understanding of the ecology, evolution and control of these diseases relies predominantly on theory and data on pathogen transmission in large self-sustaining ‘source’ populations of vectors representative of highly endemic areas. However, there are numerous places where environmental conditions are less favourable to vector populations, but where immigration allows them to persist. We built an epidemiological model to investigate the dynamics of six major human vector borne-diseases in such non self-sustaining ‘sink’ vector populations. The model was parameterized through a review of the literature, and we performed extensive sensitivity analysis to look at the emergence and prevalence of the pathogen that could be encountered in these populations. Despite the low vector abundance in typical sink populations, all six human diseases were able to spread in 15–55% of cases after accidental introduction. The rate of spread was much more strongly influenced by vector longevity, immigration and feeding rates, than by transmission and virulence of the pathogen. Prevalence in humans remained lower than 5% for dengue, leishmaniasis and Japanese encephalitis, but substantially higher for diseases with longer duration of infection; malaria and the American and African trypanosomiasis. Vector-related parameters were again the key factors, although their influence was lower than on pathogen emergence. Our results emphasize the need for ecology and evolution to be thought in the context of metapopulations made of a mosaic of sink and source habitats, and to design vector control program not only targeting areas of high vector density, but working at a larger spatial scale. PMID:22629337

  5. Emergence and prevalence of human vector-borne diseases in sink vector populations.

    Science.gov (United States)

    Rascalou, Guilhem; Pontier, Dominique; Menu, Frédéric; Gourbière, Sébastien

    2012-01-01

    Vector-borne diseases represent a major public health concern in most tropical and subtropical areas, and an emerging threat for more developed countries. Our understanding of the ecology, evolution and control of these diseases relies predominantly on theory and data on pathogen transmission in large self-sustaining 'source' populations of vectors representative of highly endemic areas. However, there are numerous places where environmental conditions are less favourable to vector populations, but where immigration allows them to persist. We built an epidemiological model to investigate the dynamics of six major human vector borne-diseases in such non self-sustaining 'sink' vector populations. The model was parameterized through a review of the literature, and we performed extensive sensitivity analysis to look at the emergence and prevalence of the pathogen that could be encountered in these populations. Despite the low vector abundance in typical sink populations, all six human diseases were able to spread in 15-55% of cases after accidental introduction. The rate of spread was much more strongly influenced by vector longevity, immigration and feeding rates, than by transmission and virulence of the pathogen. Prevalence in humans remained lower than 5% for dengue, leishmaniasis and Japanese encephalitis, but substantially higher for diseases with longer duration of infection; malaria and the American and African trypanosomiasis. Vector-related parameters were again the key factors, although their influence was lower than on pathogen emergence. Our results emphasize the need for ecology and evolution to be thought in the context of metapopulations made of a mosaic of sink and source habitats, and to design vector control program not only targeting areas of high vector density, but working at a larger spatial scale.

  6. Emergence and prevalence of human vector-borne diseases in sink vector populations.

    Directory of Open Access Journals (Sweden)

    Guilhem Rascalou

    Full Text Available Vector-borne diseases represent a major public health concern in most tropical and subtropical areas, and an emerging threat for more developed countries. Our understanding of the ecology, evolution and control of these diseases relies predominantly on theory and data on pathogen transmission in large self-sustaining 'source' populations of vectors representative of highly endemic areas. However, there are numerous places where environmental conditions are less favourable to vector populations, but where immigration allows them to persist. We built an epidemiological model to investigate the dynamics of six major human vector borne-diseases in such non self-sustaining 'sink' vector populations. The model was parameterized through a review of the literature, and we performed extensive sensitivity analysis to look at the emergence and prevalence of the pathogen that could be encountered in these populations. Despite the low vector abundance in typical sink populations, all six human diseases were able to spread in 15-55% of cases after accidental introduction. The rate of spread was much more strongly influenced by vector longevity, immigration and feeding rates, than by transmission and virulence of the pathogen. Prevalence in humans remained lower than 5% for dengue, leishmaniasis and Japanese encephalitis, but substantially higher for diseases with longer duration of infection; malaria and the American and African trypanosomiasis. Vector-related parameters were again the key factors, although their influence was lower than on pathogen emergence. Our results emphasize the need for ecology and evolution to be thought in the context of metapopulations made of a mosaic of sink and source habitats, and to design vector control program not only targeting areas of high vector density, but working at a larger spatial scale.

  7. Phase Aberrations in Diffraction Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Marchesini, S; Chapman, H N; Barty, A; Howells, M R; Spence, J H; Cui, C; Weierstall, U; Minor, A M

    2005-09-29

    In coherent X-ray diffraction microscopy the diffraction pattern generated by a sample illuminated with coherent x-rays is recorded, and a computer algorithm recovers the unmeasured phases to synthesize an image. By avoiding the use of a lens the resolution is limited, in principle, only by the largest scattering angles recorded. However, the imaging task is shifted from the experiment to the computer, and the algorithm's ability to recover meaningful images in the presence of noise and limited prior knowledge may produce aberrations in the reconstructed image. We analyze the low order aberrations produced by our phase retrieval algorithms. We present two methods to improve the accuracy and stability of reconstructions.

  8. Diffractive X-ray Telescopes

    OpenAIRE

    Skinner, Gerald K

    2010-01-01

    Diffractive X-ray telescopes using zone plates, phase Fresnel lenses, or related optical elements have the potential to provide astronomers with true imaging capability with resolution several orders of magnitude better than available in any other waveband. Lenses that would be relatively easy to fabricate could have an angular resolution of the order of micro-arc-seconds or even better, that would allow, for example, imaging of the distorted space- time in the immediate vicinity of the super...

  9. Wavelength-Modulated Diffraction System

    CERN Document Server

    Koganezawa, T; Nakamura, N; Yoshimura, Y; Iwasaki, H; Yamada, T; Shoji, T

    2001-01-01

    A new X-ray diffraction system has been constructed at the SR Center at Ritsumeikan University, in which the wavelength of the incident synchrotron radiation is continually and repeatedly changed over a definite range by rocking a couple of monochromator crystals while rotating a sample crystal and recording the diffraction pattern on a moving imaging plate detector. Bragg reflections appear as elongated spots and, if the wavelength range is chosen in the immediate vicinity of the absorption edge of an atom in the crystal, direct information on the phase of Bragg reflections can be derived from the intensity gradient of the elongated spots with respect to the wavelength. This method of phase determination is simple and free from the problem of intensity scaling encountered in the multi-wavelength diffraction method. When both a sample crystal and the detector are kept stationary while changing the wavelength, a pattern is obtained which is similar to Laue pattern, but there is a definite difference. The wavel...

  10. GAP Land Cover - Vector

    Data.gov (United States)

    Minnesota Department of Natural Resources — This vector dataset is a detailed (1-acre minimum), hierarchically organized vegetation cover map produced by computer classification of combined two-season pairs of...

  11. Tagged Vector Contour (TVC)

    Data.gov (United States)

    Kansas Data Access and Support Center — The Kansas Tagged Vector Contour (TVC) dataset consists of digitized contours from the 7.5 minute topographic quadrangle maps. Coverage for the state is incomplete....

  12. X-ray wavefront modeling of Bragg diffraction from crystals

    Science.gov (United States)

    Sutter, John P.

    2011-09-01

    The diffraction of an X-ray wavefront from a slightly distorted crystal can be modeled by the Takagi-Taupin theory, an extension of the well-known dynamical diffraction theory for perfect crystals. Maxwell's equations applied to a perturbed periodic medium yield two coupled differential equations in the incident and diffracted amplitude. These equations are discretized for numerical calculation into the determination of the two amplitudes on the points of an integration mesh, beginning with the incident amplitudes at the crystal's top surface. The result is a set of diffracted amplitudes on the top surface (in the Bragg geometry) or the bottom surface (in the Laue geometry), forming a wavefront that in turn can be propagated through free space using the Fresnel- Huygens equations. The performance of the Diamond Light Source I20 dispersive spectrometer has here been simulated using this method. Methods are shown for transforming displacements calculated by finite element analysis into local lattice distortions, and for efficiently performing 3-D linear interpolations from these onto the Takagi-Taupin integration mesh, allowing this method to be extended to crystals under thermal load or novel mechanical bender designs.

  13. Characterization of the microstructure in random and textured polycrystals and single crystals by diffraction line profile analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ribarik, Gabor [Department of Materials Physics, Eoetvoes University Budapest, Pazmany Peter setany 1/A, H-1117 Budapest (Hungary); Ungar, Tamas, E-mail: ungar@ludens.elte.hu [Department of Materials Physics, Eoetvoes University Budapest, Pazmany Peter setany 1/A, H-1117 Budapest (Hungary)

    2010-11-25

    Research highlights: {yields} X-ray or neutron line profile analysis becomes a powerful tool to characterize dislocation structures, crystallite size, size-distribution and planar faults when diffraction patterns are constructed by the bottom-up approach following physical principles. {yields} The microstructure of archaeological specimens can tell about the manufacturing technologies used by our ancestors. {yields} Burger vector and slip system types operating in grains of polycrystal enable to understand plastic response in structural materials and geological minerals. {yields} The type and frequency of twinning in hexagonal materials is essential to understand the durability of key engineering materials in energy production. - Abstract: X-ray or neutron diffraction patterns are simulated by convoluting defect specific profile functions based on continuum theory of elasticity. The defect related profile functions are controlled by the physically mandatory minimum number of parameters: the dislocation density, {rho}, the dislocation arrangement parameter, M, one or more parameters describing strain anisotropy where their number depends on the crystal symmetry, the median, m and the logarithmic variance, {sigma} of the log-normal size distribution function, and finally the density of stacking faults, {alpha} or the frequency of twin boundaries, {beta}. These parameters are, at the same time, among the most relevant physical parameters describing the microstructure of crystalline materials. The theoretical diffraction patterns are produced by the convolution of the defect related, physically based profile functions in the 'extended Convolutional Multiple Whole Profile' (eCMWP) software package. The usage of the software package is demonstrated by the microstructure determination in randomly-textured and textured polycrystalline and single crystals specimens of different materials.

  14. Resonance vector soliton of the Rayleigh wave.

    Science.gov (United States)

    Adamashvili, G T

    2016-02-01

    A theory of acoustic vector solitons of self-induced transparency of the Rayleigh wave is constructed. A thin resonance transition layer on an elastic surface is considered using a model of a two-dimensional gas of impurity paramagnetic atoms or quantum dots. Explicit analytical expressions for the profile and parameters of the Rayleigh vector soliton with two different oscillation frequencies is obtained, as well as simulations of this nonlinear surface acoustic wave with realistic parameters, which can be used in acoustic experiments. It is shown that the properties of a surface vector soliton of the Rayleigh wave depend on the parameters of the resonance layer, the elastic medium, and the transverse structure of the surface acoustic wave.

  15. On Magnetohydrodynamic Gauge Field Theory

    OpenAIRE

    Webb, G. M.; Anco, S. C.

    2017-01-01

    Clebsch potential gauge field theory for magnetohydrodynamics is developed based in part on the theory of Calkin (1963). It is shown how the polarization vector ${\\bf P}$ in Calkin's approach, naturally arises from the Lagrange multiplier constraint equation for Faraday's equation for the magnetic induction ${\\bf B}$, or alternatively from the magnetic vector potential form of Faraday's equation. Gauss's equation, (divergence of ${\\bf B}$ is zero), is incorporated in the variational principle...

  16. Quantum Optics, Diffraction Theory, and Elementary Particle Physics

    CERN Multimedia

    CERN. Geneva

    2009-01-01

    Physical optics has expanded greatly in recent years. Though it remains part of the ancestry of elementary particle physics, there are once again lessons to be learned from it. I shall discuss several of these, including some that have emerged at CERN and Brookhaven.

  17. The Extended Nijboer-Zernike Diffraction Theory and its Applications

    NARCIS (Netherlands)

    Van Haver, S.

    2010-01-01

    In present-day society, we encounter optical systems on a daily basis. Most people have a DVD player capable of playing content stored on an optical disc, Big Brother is watching us nearly everywhere using surveillance cameras and we consider it to be normal to take photographs with our mobile

  18. Syngeneic AAV pseudo-vectors potentiates full vector transduction

    Science.gov (United States)

    An excessive amount of empty capsids are generated during regular AAV vector production process. These pseudo-vectors often remain in final vectors used for animal studies or clinical trials. The potential effects of these pseudo-vectors on AAV transduction have been a major concern. In the current ...

  19. Probability theory and mathematical statistics for engineers

    CERN Document Server

    Pugachev, V S

    1984-01-01

    Probability Theory and Mathematical Statistics for Engineers focuses on the concepts of probability theory and mathematical statistics for finite-dimensional random variables.The publication first underscores the probabilities of events, random variables, and numerical characteristics of random variables. Discussions focus on canonical expansions of random vectors, second-order moments of random vectors, generalization of the density concept, entropy of a distribution, direct evaluation of probabilities, and conditional probabilities. The text then examines projections of random vector

  20. 50 years of fiber diffraction.

    Science.gov (United States)

    Holmes, Kenneth C

    2010-05-01

    In 1955 Ken Holmes started working on tobacco mosaic virus (TMV) as a research student with Rosalind Franklin at Birkbeck College, London. Afterward he spent 18months as a post doc with Don Caspar and Carolyn Cohen at the Children's Hospital, Boston where he continued the work on TMV and also showed that the core of the thick filament of byssus retractor muscle from mussels is made of two-stranded alpha-helical coiled-coils. Returning to England he joined Aaron Klug's group at the newly founded Laboratory of Molecular Biology in Cambridge. Besides continuing the TMV studies, which were aimed at calculating the three-dimensional density map of the virus, he collaborated with Pringle's group in Oxford to show that two conformation of the myosin cross-bridge could be identified in insect flight muscle. In 1968 he opened the biophysics department at the Max Planck Institute for Medical Research in Heidelberg, Germany. With Gerd Rosenbaum he initiated the use of synchrotron radiation as a source for X-ray diffraction. In his lab the TMV structure was pushed to 4A resolution and showed how the RNA binds to the protein. With his co-workers he solved the structure of g-actin as a crystalline complex and then solved the structure of the f-actin filament by orientating the g-actin structure so as to give the f-actin fiber diffraction pattern. He was also able to solve the structure of the complex of actin with tropomyosin from fiber diffraction. Copyright 2010 Elsevier Inc. All rights reserved.

  1. Inclusive diffraction and factorisation at HERA

    CERN Document Server

    Wing, M

    2008-01-01

    In this article, recent measurements of diffraction in deep inelastic scattering are presented along with QCD fits to extract the partonic structure of the exchange. These so-called diffractive parton density functions can then be used in predictions for other processes to test factorisation in diffraction. This is an important verification of QCD and has significance for predicting exotic signals such as diffractive Higgs production at the LHC.

  2. Extended Mixed Vector Equilibrium Problems

    Directory of Open Access Journals (Sweden)

    Mijanur Rahaman

    2014-01-01

    Full Text Available We study extended mixed vector equilibrium problems, namely, extended weak mixed vector equilibrium problem and extended strong mixed vector equilibrium problem in Hausdorff topological vector spaces. Using generalized KKM-Fan theorem (Ben-El-Mechaiekh et al.; 2005, some existence results for both problems are proved in noncompact domain.

  3. Vector Potential Quantization and the Quantum Vacuum

    Directory of Open Access Journals (Sweden)

    Constantin Meis

    2014-01-01

    Full Text Available We investigate the quantization of the vector potential amplitude of the electromagnetic field to a single photon state starting from the fundamental link equations between the classical electromagnetic theory and the quantum mechanical expressions. The resulting wave-particle formalism ensures a coherent transition between the classical electromagnetic wave theory and the quantum representation. A quantization constant of the photon vector potential is defined. A new quantum vacuum description results directly in having very low energy density. The calculated spontaneous emission rate and Lambs shift for the nS states of the hydrogen atom are in agreement with quantum electrodynamics. This low energy quantum vacuum state might be compatible with recent astrophysical observations.

  4. Diffraction phase and fluorescence microscopy.

    Science.gov (United States)

    Park, Yongkeun; Popescu, Gabriel; Badizadegan, Kamran; Dasari, Ramachandra R; Feld, Michael S

    2006-09-04

    We have developed diffraction phase and fluorescence (DPF) microscopy as a new technique for simultaneous quantitative phase imaging and epi-fluorescence investigation of live cells. The DPF instrument consists of an interference microscope, which is incorporated into a conventional inverted fluorescence microscope. The quantitative phase images are characterized by sub-nanometer optical path-length stability over periods from milliseconds to a cell lifetime. The potential of the technique for quantifying rapid nanoscale motions in live cells is demonstrated by experiments on red blood cells, while the composite phase-fluorescence imaging mode is exemplified with mitotic kidney cells.

  5. DIFFRACTION DISSOCIATION - 50 YEARS LATER.

    Energy Technology Data Exchange (ETDEWEB)

    WHITE, S.N.

    2005-04-27

    The field of Diffraction Dissociation, which is the subject of this workshop, began 50 years ago with the analysis of deuteron stripping in low energy collisions with nuclei. We return to the subject in a modern context- deuteron dissociation in {radical}s{sub NN} = 200 GeV d-Au collisions recorded during the 2003 RHIC run in the PHENIX experiment. At RHIC energy, d {yields} n+p proceeds predominantly (90%) through Electromagnetic Dissociation and the remaining fraction via the hadronic shadowing described by Glauber. Since the dissociation cross section has a small theoretical error we adopt this process to normalize other cross sections measured in RHIC.

  6. Could dark energy be vector-like?

    Science.gov (United States)

    Armendáriz-Picón, C.

    2004-07-01

    In this paper I explore whether a vector field can be the origin of the present stage of cosmic acceleration. In order to avoid violations of isotropy, the vector has be part of a 'cosmic triad', that is, a set of three identical vectors pointing in mutually orthogonal spatial directions. A triad is indeed able to drive a stage of late accelerated expansion in the universe, and there exist tracking attractors that render cosmic evolution insensitive to initial conditions. However, as in most other models, the onset of cosmic acceleration is determined by a parameter that has to be tuned to reproduce current observations. The triad equation of state can be sufficiently close to minus one today, and for tachyonic models it might be even less than that. I briefly analyse linear cosmological perturbation theory in the presence of a triad. It turns out that the existence of non-vanishing spatial vectors invalidates the decomposition theorem, i.e. scalar, vector and tensor perturbations do not decouple from each other. In a simplified case it is possible to analytically study the stability of the triad along the different cosmological attractors. The triad is classically stable during inflation, radiation and matter domination, but it is unstable during (late time) cosmic acceleration. I argue that this instability is not likely to have a significant impact at present.

  7. Ultrafast electron diffraction from aligned molecules

    Energy Technology Data Exchange (ETDEWEB)

    Centurion, Martin [Univ. of Nebraska, Lincoln, NE (United States)

    2015-08-17

    The aim of this project was to record time-resolved electron diffraction patterns of aligned molecules and to reconstruct the 3D molecular structure. The molecules are aligned non-adiabatically using a femtosecond laser pulse. A femtosecond electron pulse then records a diffraction pattern while the molecules are aligned. The diffraction patterns are then be processed to obtain the molecular structure.

  8. Atom–surface diffraction: a trajectory description

    National Research Council Canada - National Science Library

    Guantes, R; Sanz, A.S; Margalef-Roig, J; Miret-Artés, S

    2004-01-01

    ... with the electron diffraction experiments performed by Davisson and Germer [3] ), paving the way for the new description of matter. However, putting aside their conceptual implications, diffraction experiments have been widely used with practical purposes. Nowadays low energy He-atom diffraction from surfaces has become a well established and valuabl...

  9. Undergraduate Experiment with Fractal Diffraction Gratings

    Science.gov (United States)

    Monsoriu, Juan A.; Furlan, Walter D.; Pons, Amparo; Barreiro, Juan C.; Gimenez, Marcos H.

    2011-01-01

    We present a simple diffraction experiment with fractal gratings based on the triadic Cantor set. Diffraction by fractals is proposed as a motivating strategy for students of optics in the potential applications of optical processing. Fraunhofer diffraction patterns are obtained using standard equipment present in most undergraduate physics…

  10. Vector Addition System Reversible Reachability Problem

    OpenAIRE

    Leroux, Jérôme

    2013-01-01

    International audience; The reachability problem for vector addition systems is a central problem of net theory. This problem is known to be decidable but the complexity is still unknown. Whereas the problem is EXPSPACE-hard, no elementary upper bounds complexity are known. In this paper we consider the reversible reachability problem. This problem consists to decide if two configurations are reachable one from each other, or equivalently if they are in the same strongly connected component o...

  11. Adjustment of diffraction efficiency of polarization holograms in azobenzene polymers films using electric field

    Science.gov (United States)

    Davidenko, N. A.; Davidenko, I. I.; Pavlov, V. A.; Chuprina, N. G.; Tarasenko, V. V.; Studzinsky, S. L.

    2017-07-01

    There have been two effects of the external electric field influence on the diffraction efficiency of reconstructed holograms observed in the films of copolymers 4-[(2-nitrophenyl)diazenyl]phenyl methacrylate with octylmethacrylate, when holographic recording of the plane wave front for parallel and orthogonal orientation of polarization vectors of light beams was performed at room temperature. After recording at exposure with small energies, diffraction efficiency in the electric field formed by corona discharge decreases, while with large exposure energies, it increases. Diffraction efficiency and recording velocity are higher in copolymer with lower softening temperature. The first effect is caused by reorientation of the dipole moments of azobenzene isomer fragments in the electric field, while the growth of diffraction efficiency is explained by the increase in the amplitude of regular geometric relief of the film surface, which appears during formation of the polarization hologram.

  12. Electromagnetic scattering theory

    Science.gov (United States)

    Bird, J. F.; Farrell, R. A.

    1986-01-01

    Electromagnetic scattering theory is discussed with emphasis on the general stochastic variational principle (SVP) and its applications. The stochastic version of the Schwinger-type variational principle is presented, and explicit expressions for its integrals are considered. Results are summarized for scalar wave scattering from a classic rough-surface model and for vector wave scattering from a random dielectric-body model. Also considered are the selection of trial functions and the variational improvement of the Kirchhoff short-wave approximation appropriate to large size-parameters. Other applications of vector field theory discussed include a general vision theory and the analysis of hydromagnetism induced by ocean motion across the geomagnetic field. Levitational force-torque in the magnetic suspension of the disturbance compensation system (DISCOS), now deployed in NOVA satellites, is also analyzed using the developed theory.

  13. Spectral partitioning in diffraction tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lehman, S K; Chambers, D H; Candy, J V

    1999-06-14

    The scattering mechanism of diffraction tomography is described by the integral form of the Helmholtz equation. The goal of diffraction tomography is to invert this equation in order to reconstruct the object function from the measured scattered fields. During the forward propagation process, the spatial spectrum of the object under investigation is ''smeared,'' by a convolution in the spectral domain, across the propagating and evanescent regions of the received field. Hence, care must be taken in performing the reconstruction, as the object's spectral information has been moved into regions where it may be considered to be noise rather than useful information. This will reduce the quality and resolution of the reconstruction. We show haw the object's spectrum can be partitioned into resolvable and non-resolvable parts based upon the cutoff between the propagating and evanescent fields. Operating under the Born approximation, we develop a beam-forming on transmit approach to direct the energy into either the propagating or evanescent parts of the spectrum. In this manner, we may individually interrogate the propagating and evanescent regions of the object spectrum.

  14. Diffractive molecular-orbital tomography

    Science.gov (United States)

    Zhai, Chunyang; Zhu, Xiaosong; Lan, Pengfei; Wang, Feng; He, Lixin; Shi, Wenjing; Li, Yang; Li, Min; Zhang, Qingbin; Lu, Peixiang

    2017-03-01

    High-order-harmonic generation in the interaction of femtosecond lasers with atoms and molecules opens the path to molecular-orbital tomography and to probe the electronic dynamics with attosecond-Ångström resolutions. Molecular-orbital tomography requires both the amplitude and phase of the high-order harmonics. Yet the measurement of phases requires sophisticated techniques and represents formidable challenges at present. Here we report a scheme, called diffractive molecular-orbital tomography, to retrieve the molecular orbital solely from the amplitude of high-order harmonics without measuring any phase information. We have applied this method to image the molecular orbitals of N2, CO2, and C2H2 . The retrieved orbital is further improved by taking account the correction of Coulomb potential. The diffractive molecular-orbital tomography scheme, removing the roadblock of phase measurement, significantly simplifies the molecular-orbital tomography procedure and paves an efficient and robust way to the imaging of more complex molecules.

  15. Flatland optics. III. Achromatic diffraction.

    Science.gov (United States)

    Lohmann, A W; Pe'er, A; Wang, D; Friesem, A A

    2001-09-01

    In the previous two sections of "Flatland optics" [J. Opt. Soc. Am. A 17, 1755 (2000); 18, 1056 (2001)] we described the basic principles of two-dimensional (2D) optics and showed that a wavelength lambda in three-dimensional (3D) space (x, y, z) may appear in Flatland (x, z) as a wave with another wavelength Lambda=lambda/cos alpha. The tilt angle alpha can be modified by a 3D-Spaceland individual, who then is able to influence the 2D optics in a way that must appear to be magical to 2D-Flatland individuals-in the spirit of E. A. Abbott's science fiction story of 1884 [Flatland, a Romance of Many Dimensions, 6th ed. (Dover, New York, 1952)]. Here we show how the light from a white source can be perceived in Flatland as perfectly monochromatic, so diffraction with white light will be free of color blurring and the contrast of interference fringes can be 100%. The basic considerations for perfectly achromatic diffraction are presented, along with experimental illustration of Talbot self-imaging performed with broadband illumination.

  16. Bunyavirus-Vector Interactions

    Directory of Open Access Journals (Sweden)

    Kate McElroy Horne

    2014-11-01

    Full Text Available The Bunyaviridae family is comprised of more than 350 viruses, of which many within the Hantavirus, Orthobunyavirus, Nairovirus, Tospovirus, and Phlebovirus genera are significant human or agricultural pathogens. The viruses within the Orthobunyavirus, Nairovirus, and Phlebovirus genera are transmitted by hematophagous arthropods, such as mosquitoes, midges, flies, and ticks, and their associated arthropods not only serve as vectors but also as virus reservoirs in many cases. This review presents an overview of several important emerging or re-emerging bunyaviruses and describes what is known about bunyavirus-vector interactions based on epidemiological, ultrastructural, and genetic studies of members of this virus family.

  17. Free topological vector spaces

    OpenAIRE

    Gabriyelyan, Saak S.; Morris, Sidney A.

    2016-01-01

    We define and study the free topological vector space $\\mathbb{V}(X)$ over a Tychonoff space $X$. We prove that $\\mathbb{V}(X)$ is a $k_\\omega$-space if and only if $X$ is a $k_\\omega$-space. If $X$ is infinite, then $\\mathbb{V}(X)$ contains a closed vector subspace which is topologically isomorphic to $\\mathbb{V}(\\mathbb{N})$. It is proved that if $X$ is a $k$-space, then $\\mathbb{V}(X)$ is locally convex if and only if $X$ is discrete and countable. If $X$ is a metrizable space it is shown ...

  18. Matrix vector analysis

    CERN Document Server

    Eisenman, Richard L

    2005-01-01

    This outstanding text and reference applies matrix ideas to vector methods, using physical ideas to illustrate and motivate mathematical concepts but employing a mathematical continuity of development rather than a physical approach. The author, who taught at the U.S. Air Force Academy, dispenses with the artificial barrier between vectors and matrices--and more generally, between pure and applied mathematics.Motivated examples introduce each idea, with interpretations of physical, algebraic, and geometric contexts, in addition to generalizations to theorems that reflect the essential structur

  19. Multithreading in vector processors

    Energy Technology Data Exchange (ETDEWEB)

    Evangelinos, Constantinos; Kim, Changhoan; Nair, Ravi

    2018-01-16

    In one embodiment, a system includes a processor having a vector processing mode and a multithreading mode. The processor is configured to operate on one thread per cycle in the multithreading mode. The processor includes a program counter register having a plurality of program counters, and the program counter register is vectorized. Each program counter in the program counter register represents a distinct corresponding thread of a plurality of threads. The processor is configured to execute the plurality of threads by activating the plurality of program counters in a round robin cycle.

  20. Categorification and higher representation theory

    CERN Document Server

    Beliakova, Anna

    2017-01-01

    The emergent mathematical philosophy of categorification is reshaping our view of modern mathematics by uncovering a hidden layer of structure in mathematics, revealing richer and more robust structures capable of describing more complex phenomena. Categorified representation theory, or higher representation theory, aims to understand a new level of structure present in representation theory. Rather than studying actions of algebras on vector spaces where algebra elements act by linear endomorphisms of the vector space, higher representation theory describes the structure present when algebras act on categories, with algebra elements acting by functors. The new level of structure in higher representation theory arises by studying the natural transformations between functors. This enhanced perspective brings into play a powerful new set of tools that deepens our understanding of traditional representation theory. This volume exhibits some of the current trends in higher representation theory and the diverse te...

  1. Chiral effective field theories of the strong interactions

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, M.R. [Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208 (United States); Scherer, S. [Institut fur Kernphysik, Johannes Gutenberg-Universitat, 55099 Mainz (Germany)

    2011-09-15

    Effective field theories of the strong interactions based on the approximate chiral symmetry of QCD provide a model-independent approach to low-energy hadron physics. We give a brief introduction to mesonic and baryonic chiral perturbation theory and discuss a number of applications. We also consider the effective field theory including vector and axial-vector mesons. (authors)

  2. Diffractive X-Ray Telescopes

    Science.gov (United States)

    Skinner, Gerald K.

    2010-01-01

    Diffractive X-ray telescopes, using zone plates, phase Fresnel lenses, or related optical elements have the potential to provide astronomers with true imaging capability with resolution many orders of magnitude better than available in any other waveband. Lenses that would be relatively easy to fabricate could have an angular resolution of the order of micro-arc-seconds or even better, that would allow, for example, imaging of the distorted spacetime in the immediate vicinity of the super-massive black holes in the center of active galaxies. What then is precluding their immediate adoption? Extremely long focal lengths, very limited bandwidth, and difficulty stabilizing the image are the main problems. The history, and status of the development of such lenses is reviewed here and the prospects for managing the challenges that they present are discussed.

  3. Encapsulation process for diffraction gratings.

    Science.gov (United States)

    Ratzsch, Stephan; Kley, Ernst-Bernhard; Tünnermann, Andreas; Szeghalmi, Adriana

    2015-07-13

    Encapsulation of grating structures facilitates an improvement of the optical functionality and/or adds mechanical stability to the fragile structure. Here, we introduce novel encapsulation process of nanoscale patterns based on atomic layer deposition and micro structuring. The overall size of the encapsulated structured surface area is only restricted by the size of the available microstructuring and coating devices; thus, overcoming inherent limitations of existing bonding processes concerning cleanliness, roughness, and curvature of the components. Finally, the process is demonstrated for a transmission grating. The encapsulated grating has 97.5% transmission efficiency in the -1st diffraction order for TM-polarized light, and is being limited by the experimental grating parameters as confirmed by rigorous coupled wave analysis.

  4. Support Vector Components Analysis

    NARCIS (Netherlands)

    van der Ree, Michiel; Roerdink, Johannes; Phillips, Christophe; Garraux, Gaetan; Salmon, Eric; Wiering, Marco

    2017-01-01

    In this paper we propose a novel method for learning a distance metric in the process of training Support Vector Machines (SVMs) with the radial basis function kernel. A transformation matrix is adapted in such a way that the SVM dual objective of a classification problem is optimized. By using a

  5. Orthogonalisation of Vectors

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 3. Orthogonalisation of Vectors - Matrix Decomposition and Approximation Problems. Rajendra Bhatia. General Article Volume 5 ... Author Affiliations. Rajendra Bhatia1. Indian Statistical Institute 7, SJS Sansanwal Marg, New Delhi 110 016, India.

  6. Calculus with vectors

    CERN Document Server

    Treiman, Jay S

    2014-01-01

    Calculus with Vectors grew out of a strong need for a beginning calculus textbook for undergraduates who intend to pursue careers in STEM. fields. The approach introduces vector-valued functions from the start, emphasizing the connections between one-variable and multi-variable calculus. The text includes early vectors and early transcendentals and includes a rigorous but informal approach to vectors. Examples and focused applications are well presented along with an abundance of motivating exercises. All three-dimensional graphs have rotatable versions included as extra source materials and may be freely downloaded and manipulated with Maple Player; a free Maple Player App is available for the iPad on iTunes. The approaches taken to topics such as the derivation of the derivatives of sine and cosine, the approach to limits, and the use of "tables" of integration have been modified from the standards seen in other textbooks in order to maximize the ease with which students may comprehend the material. Additio...

  7. Vector-borne Infections

    Centers for Disease Control (CDC) Podcasts

    2011-04-18

    This podcast discusses emerging vector-borne pathogens, their role as prominent contributors to emerging infectious diseases, how they're spread, and the ineffectiveness of mosquito control methods.  Created: 4/18/2011 by National Center for Emerging Zoonotic and Infectious Diseases (NCEZID).   Date Released: 4/27/2011.

  8. Spatiotemporal response of crystals in x-ray Bragg diffraction

    Science.gov (United States)

    Shvyd'ko, Yuri; Lindberg, Ryan

    2012-10-01

    The spatiotemporal response of crystals in x-ray Bragg diffraction resulting from excitation by an ultrashort, laterally confined x-ray pulse is studied theoretically. The theory presents an extension of the analysis in symmetric reflection geometry [R. R. Lindberg and Y. V. Shvyd’ko, Phys. Rev. ST Accel. Beams 15, 050706 (2012)PRABFM1098-440210.1103/PhysRevSTAB.15.050706] to the generic case, which includes Bragg diffraction both in reflection (Bragg) and transmission (Laue) asymmetric scattering geometries. The spatiotemporal response is presented as a product of a crystal-intrinsic plane-wave spatiotemporal response function and an envelope function defined by the crystal-independent transverse profile of the incident beam and the scattering geometry. The diffracted wave fields exhibit amplitude modulation perpendicular to the propagation direction due to both angular dispersion and the dispersion due to Bragg’s law. The characteristic measure of the spatiotemporal response is expressed in terms of a few parameters: the extinction length, crystal thickness, Bragg angle, asymmetry angle, and the speed of light. Applications to self-seeding of hard x-ray free-electron lasers are discussed, with particular emphasis on the relative advantages of using either the Bragg or Laue scattering geometries. Intensity front inclination in asymmetric diffraction can be used to make snapshots of ultrafast processes with femtosecond resolution.

  9. Spatiotemporal response of crystals in x-ray Bragg diffraction

    Directory of Open Access Journals (Sweden)

    Yuri Shvyd’ko

    2012-10-01

    Full Text Available The spatiotemporal response of crystals in x-ray Bragg diffraction resulting from excitation by an ultrashort, laterally confined x-ray pulse is studied theoretically. The theory presents an extension of the analysis in symmetric reflection geometry [R. R. Lindberg and Y. V. Shvyd’ko, Phys. Rev. ST Accel. Beams 15, 050706 (2012PRABFM1098-440210.1103/PhysRevSTAB.15.050706] to the generic case, which includes Bragg diffraction both in reflection (Bragg and transmission (Laue asymmetric scattering geometries. The spatiotemporal response is presented as a product of a crystal-intrinsic plane-wave spatiotemporal response function and an envelope function defined by the crystal-independent transverse profile of the incident beam and the scattering geometry. The diffracted wave fields exhibit amplitude modulation perpendicular to the propagation direction due to both angular dispersion and the dispersion due to Bragg’s law. The characteristic measure of the spatiotemporal response is expressed in terms of a few parameters: the extinction length, crystal thickness, Bragg angle, asymmetry angle, and the speed of light. Applications to self-seeding of hard x-ray free-electron lasers are discussed, with particular emphasis on the relative advantages of using either the Bragg or Laue scattering geometries. Intensity front inclination in asymmetric diffraction can be used to make snapshots of ultrafast processes with femtosecond resolution.

  10. A new model based on group theory for correlating vibrational displacement vectors of attached atoms and shapes of the central atom otbitals in ABn(n=2-5 molecules

    Directory of Open Access Journals (Sweden)

    R. Tayebee

    2003-12-01

    Full Text Available   Stretching and bending normal vibrations of AB2(C2v, AB3(D3h, AB4(D4h, and AB5(D3h molecules are described by correlating the vibrational displacement vectors of the attached atoms with the standard representations of s, p and d atomic orbitals of the central atom in ABn(n=2-5 molecules. It is found that stretching and bending normal vibrations of simple molecules accord with probability density of hybrid orbitals of the central atom. So, stretching and bending normal vibrations can be determined based on the irreducible representations of each vibration, and symbols for the representations which are suggested by Muliken.

  11. About some practical aspects of X-ray diffraction : From single crystal to powders

    Energy Technology Data Exchange (ETDEWEB)

    Giacovazzo, C. [Bari Univ. (Italy). Dip. Geomineralogico

    1996-09-01

    An ideal polycrystalline material or power is an ensemble of a very large number of randomly oriented crystallites. It is shown the effect that this random orientation has on the diffraction of a specimen assumed to contain only one reciprocal lattice node. The most remarkable difference with the single-crystal case is that now must think of scattering vectors not as lying on discrete nodes of reciprocal lattice vectors, the distances from the single-crystal reciprocal lattice nodes to the origin of reciprocal space.

  12. Diffraction analysis for DMD-based scene projectors in the long-wave infrared.

    Science.gov (United States)

    Han, Qing; Zhang, Jianzhong; Wang, Jian; Sun, Qiang

    2016-10-01

    Diffraction effects play a significant role in the digital micromirror device (DMD)-based scene projectors in the long-wave infrared (IR) band (8-12 μm). The contrast provided by these projector systems can become noticeably worse because of the diffraction characteristics of the DMD. We apply a diffraction grating model of the DMD based on the scalar diffraction theory and the Fourier transform to address this issue. In addition, a simulation calculation is conducted with MATLAB. Finally, the simulation result is verified with an experiment. The simulation and experimental results indicate that, when the incident azimuth angle is 0° and the zenith angle is between 42°and 46°, the scene projectors will have a good imaging contrast in the long-wave IR. The diffraction grating model proposed in this study provides a method to improve the contrast of DMD-based scene projectors in the long-wave IR.

  13. Dynamical effects in Bragg coherent x-ray diffraction imaging of finite crystals

    Science.gov (United States)

    Shabalin, A. G.; Yefanov, O. M.; Nosik, V. L.; Bushuev, V. A.; Vartanyants, I. A.

    2017-08-01

    We present simulations of Bragg coherent x-ray diffractive imaging (CXDI) data from finite crystals in the frame of the dynamical theory of x-ray diffraction. The developed approach is based on a numerical solution of modified Takagi-Taupin equations and can be applied for modeling of a broad range of x-ray diffraction experiments with finite three-dimensional crystals of arbitrary shape also in the presence of strain. We performed simulations for nanocrystals of a cubic and hemispherical shape of different sizes and provided a detailed analysis of artifacts in the Bragg CXDI reconstructions introduced by the dynamical diffraction. Based on our theoretical analysis we developed an analytical procedure to treat effects of refraction and absorption in the reconstruction. Our results elucidate limitations for the kinematical approach in the Bragg CXDI and suggest a natural criterion to distinguish between kinematical and dynamical cases in coherent x-ray diffraction on a finite crystal.

  14. Inclusive τ lepton hadronic decay in vector and axial-vector channels within dispersive approach to QCD

    Energy Technology Data Exchange (ETDEWEB)

    Nesterenko, A. V. [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, 141980, Russian Federation E-mail: nesterav@theor.jinr.ru (Russian Federation)

    2016-01-22

    The dispersive approach to QCD, which properly embodies the intrinsically nonperturbative constraints originating in the kinematic restrictions on relevant physical processes and extends the applicability range of perturbation theory towards the infrared domain, is briefly overviewed. The study of OPAL (update 2012) and ALEPH (update 2014) experimental data on inclusive τ lepton hadronic decay in vector and axial-vector channels within dispersive approach is presented.

  15. Analytical And Numerical Approaches For Diffraction Efficiency In Low-curvature Curved Crystals

    Science.gov (United States)

    Bellucci, V.; Camattari, R.; Guidi, V.; Neri, I.

    2011-09-01

    Crystals with curved diffraction planes (CDPC) are an emerging technology in X-ray optics. CDPC allow manipulating the trajectories of high-energy photons with efficiency near the unity in a broad energy range. An elective application of CDPC is the construction of hard X-ray lenses. Up to now, the impossibility to focalize hard X-rays left the observation of the sky in this energy range to direct-view instruments, featuring low sensitivity and resolution. In fact, only the spectra of few and strongest sources is known above 70 keV. Mosaic crystals have already been implemented for the construction of focusing optics, but they show low reproducibility in the fabrication, and diffraction efficiency is physically limited to 50% at most. The theory of diffraction in curved crystals was developed in the past half century in the frame of the dynamical theory of diffraction, with particular contribution by C. Malgrange If the curvature is quite strong, is possible to find a simple expression to quantitatively determine the fraction of diffracted photons. To date, it exists no analytical theory that quantitatively calculates the diffraction efficiency for crystals of low curvature. Indeed, the applications of CDPC sometimes requires a curvature radius in this range. For this reason, we developed a model, which is able to produce realistic previsions of the diffraction efficiency of a thick crystal in Laue geometry for any curvature radius. The model agrees with the results of the dynamical theory when this latter is applicable. It also leads to the same results of the flat crystal case when the curvature radius is very large, and gives a realistic and quantitative description of diffraction efficiency when these two cases are not applicable.

  16. Diffraction-assisted micropatterning of silicon surfaces by ns-laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Haro-Poniatowski, E., E-mail: haro@xanum.uam.mx; Acosta-Zepeda, C.; Mecalco, G.; Hernández-Pozos, J. L. [Departamento de Física, Universidad Autónoma Metropolitana Iztapalapa, Av. San Rafael Atlixco No. 186, Col. Vicentina, C.P. 09340 México D. F. (Mexico); Batina, N.; Morales-Reyes, I. [Departamento de Química, Universidad Autónoma Metropolitana Iztapalapa, Av. San Rafael Atlixco No. 186, Col. Vicentina, C.P. 09340 México D. F. (Mexico); Bonse, J. [BAM Bundesanstalt für Materialforschung und-prüfung, Unter den Eichen 87, D-12205 Berlin (Germany)

    2014-06-14

    Single-pulse (532 nm, 8 ns) micropatterning of silicon with nanometric surface modulation is demonstrated by irradiating through a diffracting pinhole. The irradiation results obtained at fluences above the melting threshold are characterized by scanning electron and scanning force microscopy and reveal a good agreement with Fresnel diffraction theory. The physical mechanism is identified and discussed on basis of both thermocapillary and chemicapillary induced material transport during the molten state of the surface.

  17. Phase modulation of a neutron wave and diffraction of ultracold neutrons on a moving grating

    Energy Technology Data Exchange (ETDEWEB)

    Frank, A.I.; Balashov, S.N.; Bondarenko, I.V.; Geltenbort, P.; Hoeghoej, P.; Masalovich, S.V.; Nosov, V.G

    2003-05-05

    We report the result of the experiment of UCN diffraction on a moving grating. The resulting spectrum is found to be discrete in good agreement with theory. This purely quantum effect may be interpret as a result of phase modulation of the neutron wave or as diffraction in time. Also, this experiment demonstrates the validity of the Galilean transformation of the neutron wave function in a new and very clear way.

  18. Beyond generalized Proca theories

    Energy Technology Data Exchange (ETDEWEB)

    Heisenberg, Lavinia, E-mail: lavinia.heisenberg@eth-its.ethz.ch [Institute for Theoretical Studies, ETH Zurich, Clausiusstrasse 47, 8092 Zurich (Switzerland); Kase, Ryotaro; Tsujikawa, Shinji [Department of Physics, Faculty of Science, Tokyo University of Science, 1-3, Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)

    2016-09-10

    We consider higher-order derivative interactions beyond second-order generalized Proca theories that propagate only the three desired polarizations of a massive vector field besides the two tensor polarizations from gravity. These new interactions follow the similar construction criteria to those arising in the extension of scalar–tensor Horndeski theories to Gleyzes–Langlois–Piazza–Vernizzi (GLPV) theories. On the isotropic cosmological background, we show the existence of a constraint with a vanishing Hamiltonian that removes the would-be Ostrogradski ghost. We study the behavior of linear perturbations on top of the isotropic cosmological background in the presence of a matter perfect fluid and find the same number of propagating degrees of freedom as in generalized Proca theories (two tensor polarizations, two transverse vector modes, and two scalar modes). Moreover, we obtain the conditions for the avoidance of ghosts and Laplacian instabilities of tensor, vector, and scalar perturbations. We observe key differences in the scalar sound speed, which is mixed with the matter sound speed outside the domain of generalized Proca theories.

  19. Incorporating mask topography edge diffraction in photolithography simulations

    Science.gov (United States)

    Tirapu-Azpiroz, Jaione; Yablonovitch, Eli

    2006-04-01

    In deep ultraviolet lithography simulations, conventional application of Kirchhoff's boundary conditions on the mask surface provides the so-called "thin-mask" approximation of the object field. Current subwavelength lithographic operation, however, places a serious limitation on this approximation, which fails to account for the topographical, or "thick-mask," effects. In this paper, a new simulation model is proposed that is theoretically founded on the well-established physical theory of diffraction. This model relies on the key result that diffraction effects can be interpreted as an intrinsic edge property, and modeled with just two fixed parameters: width and transmission coefficient of a locally determined boundary layer applied to each chrome edge. The proposed model accurately accounts for thick-mask effects of the fields on the mask, greatly improving the accuracy of aerial image simulations in photolithography, while maintaining a reasonable computational cost.

  20. Diffraction patterns from holographic masks generated using combined axicon and helical phase distributions

    Science.gov (United States)

    Mihailescu, M.; Preda, L.; Kusko, C.; Scarlat, E. I.

    2015-02-01

    The diffraction patterns (DPs) from helical phase distributions were intensively studied due to their peculiar capability of carrying orbital angular momentum. In the present study, we investigated the combination between a helical phase distribution and another distribution: axicon in our case. Such phase distributions were digitally embedded into holographic masks (HMs). The reconstruction step is performed by simulating the propagation through these HMs, using scalar diffraction theory, Fraunhofer approximation. The spatial intensity arrangement of the DPs is investigated linked with the radial and azimuthal constructive parameters values of the diffractive phase structures embedded in the HMs and transferred in these DPs. Keywords: helical phase distribution

  1. Diffractive optics based on modulated subwavelength-domain V-ridge gratings

    Science.gov (United States)

    Bose, Gaurav; Verhoeven, Antonie; Vartiainen, Ismo; Roussey, Matthieu; Kuittinen, Markku; Tervo, Jani; Turunen, Jari

    2016-08-01

    We study the properties of reflection-type V-ridge gratings in the subwavelength domain and describe a method to realize diffractive optical elements by using such gratings as signal carriers. In particular, we utilize a coding scheme based on position modulation of a high-frequency V-ridge carrier grating. We design and demonstrate beam splitting elements using this coding scheme, electron-beam lithography, anisotropic wet etching of silicon, hot embossing of polymer, and metal deposition. These elements have the outstanding property of operating over a large spectral range from 406 to 520 nm. The measured diffraction patterns show excellent agreement with theoretical results given by rigorous diffraction theory.

  2. Large aperture diffractive space telescope

    Science.gov (United States)

    Hyde, Roderick A.

    2001-01-01

    A large (10's of meters) aperture space telescope including two separate spacecraft--an optical primary objective lens functioning as a magnifying glass and an optical secondary functioning as an eyepiece. The spacecraft are spaced up to several kilometers apart with the eyepiece directly behind the magnifying glass "aiming" at an intended target with their relative orientation determining the optical axis of the telescope and hence the targets being observed. The objective lens includes a very large-aperture, very-thin-membrane, diffractive lens, e.g., a Fresnel lens, which intercepts incoming light over its full aperture and focuses it towards the eyepiece. The eyepiece has a much smaller, meter-scale aperture and is designed to move along the focal surface of the objective lens, gathering up the incoming light and converting it to high quality images. The positions of the two space craft are controlled both to maintain a good optical focus and to point at desired targets which may be either earth bound or celestial.

  3. Anisotropic vector Preisach particle

    CERN Document Server

    Fuezi, J

    2000-01-01

    The static 2D vector magnetic behaviour of an anisotropic silicon iron sheet is modelled by a particle which depicts its space-averaged behaviour. The magnitude of magnetization is governed by a classical Preisach operator with the projection of field strength on the magnetization direction as input. Its orientation is determined by the equilibrium between the field strength orientation and the anisotropy of the sheet.

  4. Locally analytic vectors in representations of locally

    CERN Document Server

    Emerton, Matthew J

    2017-01-01

    The goal of this memoir is to provide the foundations for the locally analytic representation theory that is required in three of the author's other papers on this topic. In the course of writing those papers the author found it useful to adopt a particular point of view on locally analytic representation theory: namely, regarding a locally analytic representation as being the inductive limit of its subspaces of analytic vectors (of various "radii of analyticity"). The author uses the analysis of these subspaces as one of the basic tools in his study of such representations. Thus in this memoir he presents a development of locally analytic representation theory built around this point of view. The author has made a deliberate effort to keep the exposition reasonably self-contained and hopes that this will be of some benefit to the reader.

  5. What is a vector?

    Science.gov (United States)

    Morgan, Eric René; Booth, Mark; Norman, Rachel; Mideo, Nicole; McCallum, Hamish; Fenton, Andy

    2017-01-01

    Many important and rapidly emerging pathogens of humans, livestock and wildlife are ‘vector-borne’. However, the term ‘vector’ has been applied to diverse agents in a broad range of epidemiological systems. In this perspective, we briefly review some common definitions, identify the strengths and weaknesses of each and consider the functional differences between vectors and other hosts from a range of ecological, evolutionary and public health perspectives. We then consider how the use of designations can afford insights into our understanding of epidemiological and evolutionary processes that are not otherwise apparent. We conclude that from a medical and veterinary perspective, a combination of the ‘haematophagous arthropod’ and ‘mobility’ definitions is most useful because it offers important insights into contact structure and control and emphasizes the opportunities for pathogen shifts among taxonomically similar species with similar feeding modes and internal environments. From a population dynamics and evolutionary perspective, we suggest that a combination of the ‘micropredator’ and ‘sequential’ definition is most appropriate because it captures the key aspects of transmission biology and fitness consequences for the pathogen and vector itself. However, we explicitly recognize that the value of a definition always depends on the research question under study. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’. PMID:28289253

  6. Lentiviral Vector Mediated Transgenesis.

    Science.gov (United States)

    Barde, Isabelle; Verp, Sonia; Offner, Sandra; Trono, Didier

    2011-03-01

    The genetic manipulation of rodents through the generation of fully transgenic animals or via the modification of selective cells or organs is a procedure of paramount importance for biomedical research, either to address fundamental questions or to develop preclinical models of human diseases. Lentiviral vectors occupy the front stage in this scene, as they can mediate the integration and stable expression of transgenes both in vitro and in vivo. Widely used to modify a variety of cells, including re-implantable somatic and embryonic stem cells, lentiviral vectors can also be directly administered in vivo, for instance in the brain. However, perhaps their most spectacular research application is in the generation of transgenic animals. Compared with the three-decade-old DNA pronuclear injection technique, lentivector-mediated transgenesis is simple, cheap, and highly efficient. Furthermore, it can take full advantage of the great diversity of lentiviral vectors developed for other applications, and thus allows for ubiquitous or tissue-specific or constitutive or externally controllable transgene expression, as well as RNAi-mediated gene knockdown. Curr. Protoc. Mouse Biol. 1:169-184. © 2011 by John Wiley & Sons, Inc. Copyright © 2011 John Wiley & Sons, Inc.

  7. Propagating Gateway Vectors.

    Science.gov (United States)

    Reece-Hoyes, John S; Walhout, Albertha J M

    2018-01-02

    Generating stocks of Entry and Destination vectors for use in the Gateway recombinatorial cloning system requires transforming them into Escherichia coli strain DB3.1, where they can replicate because this strain is immune to the effects of the ccdB gene carried in the Gateway cassette. However, mutations in the ccdB gene can arise at low frequency, and these mutant plasmids will consequently allow growth of standard cloning strains of E. coli (e.g., DH5α). Therefore, after making new stocks of Gateway plasmids, their ability to grow in cloning strains of E. coli must be tested. This involves obtaining multiple stocks of vector, each arising from a single plasmid grown in a single DB3.1 bacterial colony, and transforming each stock into both DB3.1 and the preferred cloning strain of E. coli in a controlled fashion. Only vector stocks that effectively kill the standard cloning strain (i.e., no or few colonies are obtained after transformation) should be used in Gateway cloning reactions. The sequence can be performed in 3 d. © 2018 Cold Spring Harbor Laboratory Press.

  8. From population structure to genetically-engineered vectors: new ways to control vector-borne diseases?

    Science.gov (United States)

    Sparagano, O A E; De Luna, C J

    2008-07-01

    Epidemiological studies on vectors and the pathogens they can carry (such as Borrelia burgdorferi) are showing some correlations between infection rates and biodiversity highlighting the "dilution" effects on potential vectors. Meanwhile other studies comparing sympatric small rodent species demonstrated that rodent species transmitting more pathogens are parasitized by more ectoparasite species. Studies on population structure and size have also proven a difference on the intensity of the parasitic infection. Furthermore, preliminary results in genetic improvement in mosquitoes (genetic markers, sexing, and genetic sterilization) will also increase performance as it has already been shown in field applications in developing countries. Recent results have greatly improved the fitness of genetically-modified insects compared to wild type populations with new approaches such as the post-integration elimination of transposon sequences, stabilising any insertion in genetically-modified insects. Encouraging results using the Sterile Insect Technique highlighted some metabolism manipulation to avoid the viability of offspring from released parent insect in the wild. Recent studies on vector symbionts would also bring a new angle in vector control capabilities, while complete DNA sequencing of some arthropods could point out ways to block the deadly impact on animal and human populations. These new potential approaches will improve the levels of control or even in some cases would eradicate vector species and consequently the vector-borne diseases they can transmit. In this paper we review some of the population biology theories, biological control methods, and the genetic techniques that have been published in the last years that are recommended to control for vector-borne diseases.

  9. The Intensity of the Light Diffraction by Supersonic Longitudinal Waves in Solid

    Directory of Open Access Journals (Sweden)

    Minasyan V.

    2010-04-01

    Full Text Available First, we predict existence of transverse electromagnetic field created by supersonic longitudinal waves in solid. This electromagnetic wave with frequency of ultrasonic field is moved by velocity of supersonic field toward of direction propagation of one. The average Poynting vector of superposition field is calculated by presence of the transverse electromagnetic and the optical fields which in turn provides appearance the diffraction of light.

  10. Elements of mathematics topological vector spaces

    CERN Document Server

    Bourbaki, Nicolas

    2003-01-01

    This is a softcover reprint of the English translation of 1987 of the second edition of Bourbaki's Espaces Vectoriels Topologiques (1981). This second edition is a brand new book and completely supersedes the original version of nearly 30 years ago. But a lot of the material has been rearranged, rewritten, or replaced by a more up-to-date exposition, and a good deal of new material has been incorporated in this book, all reflecting the progress made in the field during the last three decades. Table of Contents. Chapter I: Topological vector spaces over a valued field. Chapter II: Convex sets and locally convex spaces. Chapter III: Spaces of continuous linear mappings. Chapter IV: Duality in topological vector spaces. Chapter V: Hilbert spaces (elementary theory). Finally, there are the usual "historical note", bibliography, index of notation, index of terminology, and a list of some important properties of Banach spaces. (Based on Math Reviews, 1983).

  11. Approximate gauge symemtry of composite vector bosons

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Mahiko

    2010-06-01

    It can be shown in a solvable field theory model that the couplings of the composite vector mesons made of a fermion pair approach the gauge couplings in the limit of strong binding. Although this phenomenon may appear accidental and special to the vector bosons made of a fermion pair, we extend it to the case of bosons being constituents and find that the same phenomenon occurs in more an intriguing way. The functional formalism not only facilitates computation but also provides us with a better insight into the generating mechanism of approximate gauge symmetry, in particular, how the strong binding and global current conservation conspire to generate such an approximate symmetry. Remarks are made on its possible relevance or irrelevance to electroweak and higher symmetries.

  12. Advection of vector fields by chaotic flows

    CERN Document Server

    Balmforth, N J; Spiegel, E A

    1993-01-01

    We have introduced a new transfer operator for chaotic flows whose leading eigenvalue yields the dynamo rate of the fast kinematic dynamo and applied cycle expansion of the Fredholm determinant of the new operator to evaluation of its spectrum. The theory hs been tested on a normal form model of the vector advecting dynamical flow. If the model is a simple map with constant time between two iterations, the dynamo rate is the same as the escape rate of scalar quantties. However, a spread in Poincaré section return times lifts the degeneracy of the vector and scalar advection rates, and leads to dynamo rates that dominate over the scalar advection rates. For sufficiently large time spreads we have even found repellers for which the magnetic field grows exponentially, even though the scalar densities are decaying exponentially.

  13. Teaching Fraunhofer diffraction via experimental and simulated images in the laboratory

    Science.gov (United States)

    Peinado, Alba; Vidal, Josep; Escalera, Juan Carlos; Lizana, Angel; Campos, Juan; Yzuel, Maria

    2012-10-01

    Diffraction is an important phenomenon introduced to Physics university students in a subject of Fundamentals of Optics. In addition, in the Physics Degree syllabus of the Universitat Autònoma de Barcelona, there is an elective subject in Applied Optics. In this subject, diverse diffraction concepts are discussed in-depth from different points of view: theory, experiments in the laboratory and computing exercises. In this work, we have focused on the process of teaching Fraunhofer diffraction through laboratory training. Our approach involves students working in small groups. They visualize and acquire some important diffraction patterns with a CCD camera, such as those produced by a slit, a circular aperture or a grating. First, each group calibrates the CCD camera, that is to say, they obtain the relation between the distances in the diffraction plane in millimeters and in the computer screen in pixels. Afterwards, they measure the significant distances in the diffraction patterns and using the appropriate diffraction formalism, they calculate the size of the analyzed apertures. Concomitantly, students grasp the convolution theorem in the Fourier domain by analyzing the diffraction of 2-D gratings of elemental apertures. Finally, the learners use a specific software to simulate diffraction patterns of different apertures. They can control several parameters: shape, size and number of apertures, 1-D or 2-D gratings, wavelength, focal lens or pixel size.Therefore, the program allows them to reproduce the images obtained experimentally, and generate others by changingcertain parameters. This software has been created in our research group, and it is freely distributed to the students in order to help their learning of diffraction. We have observed that these hands on experiments help students to consolidate their theoretical knowledge of diffraction in a pedagogical and stimulating learning process.

  14. Underwater giant enhancement of broadband diffraction efficiency of surface diffraction gratings fabricated by femtosecond laser

    Science.gov (United States)

    Zhang, Fan; Wang, Cong; Yin, Kai; Dong, Xinran; Song, Yuxin; Tian, Yaxiang; Duan, Ji'an

    2017-06-01

    In this study, a simple approach is proposed to improve the diffraction efficiency of surface diffraction gratings on fused silica fabricated by femtosecond laser. Effects of grating period, pulse energy, scanning speed and wavelength on the total diffraction efficiency are also investigated. In addition, the mechanism of the diffraction efficiency's giant enhancement is discussed by finite difference time domain (FDTD) and optical phase shift structure calculation. It is revealed that: (1) Compared with the diffraction efficiency obtained in air, the underwater image via diffraction grating is clearer than that in air and diffraction pattern in water is much brighter; (2) The diffraction efficiency increases with an increase in wavelength and scanning speed, whereas it decreases while the laser pulse energy is high; and (3) This giant enhancement is attributed to the degree of Mie scattering and refraction, which is effectively reduced for the existence of water.

  15. Diffractive Optics of Anisotropic Polarization Gratings

    NARCIS (Netherlands)

    Xu, M.

    2009-01-01

    Diffraction gratings are being used to manipulate light in many different applications, such as in flat panel display systems, modern lighting systems, and optical recording. Diffraction gratings can be made polarization selective due to form birefringence. An alternative approach to polarization

  16. Amorphouslike diffraction pattern in solid metallic titanium

    DEFF Research Database (Denmark)

    Wang, Y.; Fang, Y.Z.; Kikegawa, T.

    2005-01-01

    Amorphouslike diffraction patterns of solid elemental titanium have been detected under high pressure and high temperature using in situ energy-dispersive x-ray diffraction and a multianvil press. The onset pressure and the temperature of formation of amorphous titanium is found to be close to th...

  17. Nonlinear diffraction from a virtual beam

    DEFF Research Database (Denmark)

    Saltiel, Solomon M.; Neshev, Dragomir N.; Krolikowski, Wieslaw

    2010-01-01

    We observe experimentally a novel type of nonlinear diffraction in the process of two-wave mixing on a nonlinear quadratic grating.We demonstrate that when the nonlinear grating is illuminated simultaneously by two noncollinear beams, a second-harmonic diffraction pattern is generated by a virtua...

  18. Non-diffractive optically variable security devices

    NARCIS (Netherlands)

    Renesse, R.L. van

    1991-01-01

    At the past optical security conferences attention was focused on diffractive structures, e.g. holograms, embossed gratings and thin—film devices, as security elements on valuable documents. The main reasons for this emphasis are, that the iridescent effect of such diffractive optically variable

  19. Scalar - vector soliton fiber lasers

    CERN Document Server

    Wu, Zhichao; Li, Lei; Luo, Yiyang; Tang, Dingyuan; Shen, Deyuan; Tang, Ming; Fu, Songnian; Zhao, Luming

    2016-01-01

    Rapid progress in passively mode-locked fiber lasers is currently driven by the recent discovery of vector feature of mode-locking pulses, namely, the group velocity-locked vector solitons, the phase locked vector solitons, and the high-order vector solitons. Those vector solitons are fundamentally different from the previously known scalar solitons. Here, we report a fiber laser where the mode-locked pulse evolves as a vector soliton in the strong birefringent segment and is transformed into a regular scalar soliton after the polarizer within the laser cavity. The existence of solutions in a polarization-dependent cavity comprising a periodic combination of two distinct nonlinear waves is novel and likely to be applicable to various other nonlinear systems. For very large local birefringence, our laser approaches the working regime of vector soliton lasers, while it approaches scalar soliton fiber lasers under the conditions of very small birefringence.

  20. Femtosecond diffractive imaging of biological cells

    Energy Technology Data Exchange (ETDEWEB)

    Marvin Seibert, M; Boutet, Sebastien; Svenda, Martin; Ekeberg, Tomas; Maia, Filipe R N C; TImneanu, Nicusor; Caleman, Carl; Hajdu, Janos [Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Husargatan 3, Box 596, SE-75124 Uppsala (Sweden); Bogan, Michael J [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Barty, Anton; Hau-Riege, Stefan; Frank, Matthias; Benner, Henry [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Lee, Joanna Y [Department of Biology, Stanford University, Stanford, CA 94305 (United States); Marchesini, Stefano [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Shaevitz, Joshua W [150 Carl Icahn Laboratory, Princeton University, Princeton, NJ 08544 (United States); Fletcher, Daniel A [Bioengineering and Biophysics, University of California, Berkeley, CA 94720 (United States); Bajt, Sasa [Photon Science, DESY, Notkestrasse 85, 22607 Hamburg (Germany); Andersson, Inger [Department of Molecular Biology, Swedish University of Agricultural Sciences, Husargatan 3, Box 590, SE-751 24 Uppsala (Sweden); Chapman, Henry N, E-mail: marvin@xray.bmc.uu.s, E-mail: janos@xray.bmc.uu.s [Center for Free-Electron Laser Science, University of Hamburg and DESY, Notkestrasse 85, Hamburg (Germany)

    2010-10-14

    In a flash diffraction experiment, a short and extremely intense x-ray pulse illuminates the sample to obtain a diffraction pattern before the onset of significant radiation damage. The over-sampled diffraction pattern permits phase retrieval by iterative phasing methods. Flash diffractive imaging was first demonstrated on an inorganic test object (Chapman et al 2006 Nat. Phys. 2 839-43). We report here experiments on biological systems where individual cells were imaged, using single, 10-15 fs soft x-ray pulses at 13.5 nm wavelength from the FLASH free-electron laser in Hamburg. Simulations show that the pulse heated the sample to about 160 000 K but not before an interpretable diffraction pattern could be obtained. The reconstructed projection images return the structures of the intact cells. The simulations suggest that the average displacement of ions and atoms in the hottest surface layers remained below 3 A during the pulse.

  1. Uniting Electron Crystallography and Powder Diffraction

    CERN Document Server

    Shankland, Kenneth; Meshi, Louisa; Avilov, Anatoly; David, William

    2012-01-01

    The polycrystalline and nanocrystalline states play an increasingly important role in exploiting the properties of materials, encompassing applications as diverse as pharmaceuticals, catalysts, solar cells and energy storage. A knowledge of the three-dimensional atomic and molecular structure of materials is essential for understanding and controlling their properties, yet traditional single-crystal X-ray diffraction methods lose their power when only polycrystalline and nanocrystalline samples are available. It is here that powder diffraction and single-crystal electron diffraction techniques take over, substantially extending the range of applicability of the crystallographic principles of structure determination.  This volume, a collection of teaching contributions presented at the Crystallographic Course in Erice in 2011, clearly describes the fundamentals and the state-of-the-art of powder diffraction and electron diffraction methods in materials characterisation, encompassing a diverse range of discipl...

  2. Diffractive Photon Production in $\\gamma p$ and $\\gamma \\gamma$ Interactions

    OpenAIRE

    Evanson, N G; Forshaw, J R

    1999-01-01

    We study the diffractive production of photons in gamma-p and gamma-gamma collisions. We specifically compute the rates for gamma*-p -> gamma-X and for gamma*-gamma* -> gamma-gamma, where X denotes the proton dissociation. We focus on the rates at large momentum transfers, -t >> Lambda^2, where we are most confident in the use of QCD perturbation theory. However, our calculations do allow us to study the -t -> 0 behaviour of the gamma*-gamma*-> gamma-gamma process in the region where the inco...

  3. Review of high energy diffraction in real and virtual photon proton scattering at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, G.

    2009-07-15

    The electron-proton collider HERA at DESY opened the door for the study of diffraction in real and virtual photon-proton scattering at center-of-mass energies W up to 250 GeV and for large negative mass squared -Q{sup 2} of the virtual photon up to Q{sup 2}=1600 GeV{sup 2}. At W = 220 GeV and Q{sup 2}=4 GeV{sup 2}, diffraction accounts for about 15% of the total virtual photon proton cross section decreasing to {approx}5% at Q{sup 2}=200 GeV{sup 2}. An overview of the results obtained by the experiments H1 and ZEUS on the production of neutral vector mesons and on inclusive diffraction up to the year 2008 is presented. (orig.)

  4. Architecture and Vector Control

    DEFF Research Database (Denmark)

    von Seidlein, Lorenz; Knols, Bart GJ; Kirby, Matthew

    2012-01-01

    of vector-borne diseases have no access to electricity. Many houses in the hot, humid regions of Asia have adapted to the environment, they are built of porous materials and are elevated on stilts features which allow a comfortable climate even in the presence of bednets and screens. In contrast, many...... buildings in Africa and Asia in respect to their indoor climate characteristics and finally, show how state-of-the-art 3D modelling can predict climate characteristics and help to optimize buildings....

  5. Algorithms for quadratic matrix and vector equations

    CERN Document Server

    Poloni, Federico

    2011-01-01

    This book is devoted to studying algorithms for the solution of a class of quadratic matrix and vector equations. These equations appear, in different forms, in several practical applications, especially in applied probability and control theory. The equations are first presented using a novel unifying approach; then, specific numerical methods are presented for the cases most relevant for applications, and new algorithms and theoretical results developed by the author are presented. The book focuses on “matrix multiplication-rich” iterations such as cyclic reduction and the structured doubling algorithm (SDA) and contains a variety of new research results which, as of today, are only available in articles or preprints.

  6. Chromatic confocal microscopy using staircase diffractive surface.

    Science.gov (United States)

    Rayer, Mathieu; Mansfield, Daniel

    2014-08-10

    A chromatic confocal microscope (CCM) is a high-dynamic-range noncontact distance measurement sensor; it is based on a hyperchromatic lens. The vast majority of commercial CCMs use refractive-based chromatic dispersion to chromatically code the optical axis. This approach significantly limits the range of applications and performance of the CCM. In order to be a suitable alternative to a laser triangulation gauge and laser encoder, the performance of the CCM must be improved. In this paper, it is shown how hybrid aspheric diffractive (HAD) lenses can bring the CCM to its full potential by increasing the dynamic range by a factor of 2 and the resolution by a factor of 5 while passively athermizing and increasing the light throughput efficiency of the optical head [M. Rayer, U.S. patent 1122052.2 (2011)]. The only commercially suitable manufacturing process is single-point diamond turning. However, the optical power carried by the diffractive side of a hybrid aspheric diffractive lens is limited by the manufacturing process. A theoretical study of manufacturing losses has revealed that the HAD configuration with the highest diffraction efficiency is for a staircase diffractive surface (SDS). SDS lenses have the potential to reduce light losses associated with manufacturing limits by a factor of 5 without increasing surface roughness, allowing scalar diffraction-limited optical design with a diffractive element.

  7. Generalized projection dynamics in evolutionary game theory

    NARCIS (Netherlands)

    Joosten, Reinoud A.M.G.; Roorda, Berend

    2009-01-01

    We introduce the ray-projection dynamics in evolutionary game theory by employing a ray projection of the relative �tness (vector) function both locally and globally. By global (local) ray projection we mean a projection of the vector (close to the unit simplex) unto the unit simplex along a ray

  8. Diffraction of a Waveguide Mode in a Nanowire

    DEFF Research Database (Denmark)

    Bordo, Vladimir

    2009-01-01

    can be calculated numerically, such an approach does not allow comprehensive analysis of the problem. In the present talk, the rigorous theory of reflection and diffraction of a waveguide mode at the end of a semi-infinite dielectric circular cylinder is developed. The theory assumes an arbitrary...... ratio between the cylinder radius and the wavelength and hence it can be used for the description of the nanowire optical properties. An exact solution of this problem is found by the use of fictitious electric and magnetic current sheets located at the end of the cylinder. The solution has the form....... It is shown that the polarization of the electromagnetic field is not changed upon reflection and its amplitude is zero in the far-field limit. The extension of this approach to the case of a nanowire of a finite length is also discussed. The normal modes of such a resonator which are analogs of the Fabry...

  9. Two-dimensional x-ray diffraction

    CERN Document Server

    He, Bob B

    2009-01-01

    Written by one of the pioneers of 2D X-Ray Diffraction, this useful guide covers the fundamentals, experimental methods and applications of two-dimensional x-ray diffraction, including geometry convention, x-ray source and optics, two-dimensional detectors, diffraction data interpretation, and configurations for various applications, such as phase identification, texture, stress, microstructure analysis, crystallinity, thin film analysis and combinatorial screening. Experimental examples in materials research, pharmaceuticals, and forensics are also given. This presents a key resource to resea

  10. Genetic Synthesis of the Diffraction Profile

    Directory of Open Access Journals (Sweden)

    Stanislav Jurecka

    2004-01-01

    Full Text Available In this paper we describe theoretical synthesis of the x-ray diffraction line profile as a superposition of the spectral components Ka1 and Ka2 optimized to the experimental data by the genetic algorithm and nonlinear optimization methods 'Nelder-Mead downhill simplex' and Levenberg-Marquardt method. Such combination of global and local optimization methods results in a mathematical model of the diffraction profile, providing reliable determininig of diffraction line characteristics for the material structure properties study. Experimetal results of the optimization preocedures are given too.

  11. Fresnel diffraction patterns as accelerating beams

    CERN Document Server

    Zhang, Yiqi; Zheng, Huaibin; Wu, Zhenkun; Li, Yuanyuan; Lu, Keqing; Zhang, Yanpeng

    2013-01-01

    We demonstrate that beams originating from Fresnel diffraction patterns are self-accelerating in free space. In addition to accelerating and self-healing, they also exhibit parabolic deceleration property, which is in stark contrast to other accelerating beams. We find that the trajectory of Fresnel paraxial accelerating beams is similar to that of nonparaxial Weber beams. Decelerating and accelerating regions are separated by a critical propagation distance, at which no acceleration is present. During deceleration, the Fresnel diffraction beams undergo self-smoothing, in which oscillations of the diffracted waves gradually focus and smooth out at the critical distance.

  12. New diffractive results from the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Gallinaro, Michele; /Rockefeller U.

    2005-05-01

    Experimental results in diffractive processes are summarized and a few notable characteristics described in terms of Quantum Chromodynamics. Exclusive dijet production is used to establish a benchmark for future experiments in the quest for diffractive Higgs production at the Large Hadron Collider. Using new data from the Tevatron and dedicated diffractive triggers, no excess over a smooth falling distribution for exclusive dijet events could be found. Stringent upper limits on the exclusive dijet production cross section are presented. The quark/gluon composition of dijet final states is used to provide additional hints on exclusive dijet production.

  13. Neutron diffraction from superparamagnetic colloidal crystals

    Science.gov (United States)

    Ličen, M.; Drevenšek-Olenik, I.; Čoga, L.; Gyergyek, S.; Kralj, S.; Fally, M.; Pruner, C.; Geltenbort, P.; Gasser, U.; Nagy, G.; Klepp, J.

    2017-11-01

    We fabricated a superparamagnetic ordered structure via self-assembly of a colloidal crystal from a suspension of maghemite nanoparticles and polystyrene beads. Such crystals are potential candidates for novel polarizing beam-splitters for cold neutrons, complementing the available methods of neutron polarization. Different bead sizes and nanoparticle concentrations were tested to obtain a crystal of reasonable quality. Neutron diffraction experiments in the presence of an external magnetic field were performed on the most promising sample. We demonstrate that the diffraction efficiency of such crystals can be controlled by the magnetic field. Our measurements also indicate that the Bragg diffraction regime can be reached with colloidal crystals.

  14. A scattering approach to sea wave diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Corradini, M. L., E-mail: letizia.corradini@unicam.it; Garbuglia, M., E-mail: milena.garbuglia@unicam.it; Maponi, P., E-mail: pierluigi.maponi@unicam.it [University of Camerino, via Madonna delle Carceri, 9, 62032, Camerino (Italy); Ruggeri, M., E-mail: ru.marco@faggiolatipumps.it [Faggiolati Pumps S.p.A., Z.Ind Sforzacosta, 62100, Macerata (Italy)

    2016-06-08

    This paper intends to show a model for the diffraction of sea waves approaching an OWC device, which converts the sea waves motion into mechanical energy and then electrical energy. This is a preliminary study to the optimisation of the device, in fact the computation of sea waves diffraction around the device allows the estimation of the sea waves energy which enters into the device. The computation of the diffraction phenomenon is the result of a sea waves scattering problem, solved with an integral equation method.

  15. Diffraction and diffusion in room acoustics

    DEFF Research Database (Denmark)

    Rindel, Jens Holger; Rasmussen, Birgit

    1996-01-01

    Diffraction and diffusion are two phenomena that are both related to the wave nature of sound. Diffraction due to the finite size of reflecting surfaces and the design of single reflectors and reflector arrays are discussed. Diffusion is the result of scattering of sound reflected from surfaces...... that are not plane but curved or irregular. The importance of diffusion has been demonstrated in concert halls. Methods for the design of diffusing surfaces and the development of new types of diffusers are reviewed. Finally, the importance of diffraction and diffusion in room acoustic computer models is discussed....

  16. "Analytical" vector-functions I

    Science.gov (United States)

    Todorov, Vladimir Todorov

    2017-12-01

    In this note we try to give a new (or different) approach to the investigation of analytical vector functions. More precisely a notion of a power xn; n ∈ ℕ+ of a vector x ∈ ℝ3 is introduced which allows to define an "analytical" function f : ℝ3 → ℝ3. Let furthermore f (ξ )= ∑n =0 ∞ anξn be an analytical function of the real variable ξ. Here we replace the power ξn of the number ξ with the power of a vector x ∈ ℝ3 to obtain a vector "power series" f (x )= ∑n =0 ∞ anxn . We research some properties of the vector series as well as some applications of this idea. Note that an "analytical" vector function does not depend of any basis, which may be used in research into some problems in physics.

  17. Multidimensional Vector Model of Stimulus-Response Compatibility

    Science.gov (United States)

    Yamaguchi, Motonori; Proctor, Robert W.

    2012-01-01

    The present study proposes and examines the multidimensional vector (MDV) model framework as a modeling schema for choice response times. MDV extends the Thurstonian model, as well as signal detection theory, to classification tasks by taking into account the influence of response properties on stimulus discrimination. It is capable of accounting…

  18. Optimality Conditions in Vector Optimization

    CERN Document Server

    Jiménez, Manuel Arana; Lizana, Antonio Rufián

    2011-01-01

    Vector optimization is continuously needed in several science fields, particularly in economy, business, engineering, physics and mathematics. The evolution of these fields depends, in part, on the improvements in vector optimization in mathematical programming. The aim of this Ebook is to present the latest developments in vector optimization. The contributions have been written by some of the most eminent researchers in this field of mathematical programming. The Ebook is considered essential for researchers and students in this field.

  19. Critical Analysis of the Mathematical Formalism of Theoretical Physics. II. Foundations of Vector Calculus

    Science.gov (United States)

    Kalanov, Temur Z.

    2014-03-01

    A critical analysis of the foundations of standard vector calculus is proposed. The methodological basis of the analysis is the unity of formal logic and of rational dialectics. It is proved that the vector calculus is incorrect theory because: (a) it is not based on a correct methodological basis - the unity of formal logic and of rational dialectics; (b) it does not contain the correct definitions of ``movement,'' ``direction'' and ``vector'' (c) it does not take into consideration the dimensions of physical quantities (i.e., number names, denominate numbers, concrete numbers), characterizing the concept of ''physical vector,'' and, therefore, it has no natural-scientific meaning; (d) operations on ``physical vectors'' and the vector calculus propositions relating to the ''physical vectors'' are contrary to formal logic.

  20. Stability in quadratic torsion theories

    Science.gov (United States)

    Vasilev, Teodor Borislavov; Cembranos, Jose A. R.; Valcarcel, Jorge Gigante; Martín-Moruno, Prado

    2017-11-01

    We revisit the definition and some of the characteristics of quadratic theories of gravity with torsion. We start from a Lagrangian density quadratic in the curvature and torsion tensors. By assuming that General Relativity should be recovered when the torsion vanishes and investigating the behaviour of the vector and pseudo-vector torsion fields in the weak-gravity regime, we present a set of necessary conditions for the stability of these theories. Moreover, we explicitly obtain the gravitational field equations using the Palatini variational principle with the metricity condition implemented via a Lagrange multiplier.

  1. Extinction properties of metallic nanowires: Quantum diffraction and retardation effects

    Energy Technology Data Exchange (ETDEWEB)

    Moradi, Afshin, E-mail: a.moradi@kut.ac.ir [Department of Engineering Physics, Kermanshah University of Technology, Kermanshah (Iran, Islamic Republic of); Department of Nano Sciences, Institute for Studies in Theoretical Physics and Mathematics (IPM), Tehran (Iran, Islamic Republic of)

    2015-10-09

    The standard Mie theory for the extinction of electromagnetic radiation by a metal cylinder that is irradiated by a normally incident plane wave is extended to the case of a metallic nanowire, where two quantum longitudinal waves are excited. The modification of the Mie theory due to quantum diffraction effects is included by employing the quantum hydrodynamic approximation and applying the appropriate quantum additional boundary conditions. The extinction properties of the system and their differences with previous treatments based on the standard local and nonlocal models are shown. Also, as an example the validity of the nonretarded approximation in the quantum nonlocal optical response of a sodium nanowire is discussed. - Highlights: • Extinction properties of metallic nanowires in the presence of quantum diffraction and retardation effects are studied. • The differences of new results with previous findings based on the standard local and nonlocal models are shown. • The validity of the nonretarded approximation in the quantum nonlocal optical response of a sodium nanowire is discussed.

  2. Conformal Aspects of Spinor-Vector Duality

    CERN Document Server

    Faraggi, Alon E; Mohaupt, Thomas; Tsulaia, Mirian

    2011-01-01

    We present a detailed study of various aspects of Spinor-Vector duality in Heterotic string compactifications and expose its origin in terms of the internal conformal field theory. In particular, we illustrate the main features of the duality map by using simple toroidal orbifolds preserving N_4 = 1 and N_4 = 2 spacetime supersymmetries in four dimensions. We explain how the duality map arises in this context by turning on special values of the Wilson lines around the compact cycles of the manifold. We argue that in models with N_4 = 2 spacetime supersymmetry, the interpolation between the Spinor-Vector dual vacua can be continuously realized. We trace the origin of the Spinor-Vector duality map to the presence of underlying N = (2, 2) and N = (4, 4) SCFTs, and explicitly show that the induced spectral-flow in the twisted sectors is responsible for the observed duality. The isomorphism between current algebra representations gives rise to a number of chiral character identities, reminiscent of the recently-di...

  3. Multifractal vector fields and stochastic Clifford algebra.

    Science.gov (United States)

    Schertzer, Daniel; Tchiguirinskaia, Ioulia

    2015-12-01

    In the mid 1980s, the development of multifractal concepts and techniques was an important breakthrough for complex system analysis and simulation, in particular, in turbulence and hydrology. Multifractals indeed aimed to track and simulate the scaling singularities of the underlying equations instead of relying on numerical, scale truncated simulations or on simplified conceptual models. However, this development has been rather limited to deal with scalar fields, whereas most of the fields of interest are vector-valued or even manifold-valued. We show in this paper that the combination of stable Lévy processes with Clifford algebra is a good candidate to bridge up the present gap between theory and applications. We show that it indeed defines a convenient framework to generate multifractal vector fields, possibly multifractal manifold-valued fields, based on a few fundamental and complementary properties of Lévy processes and Clifford algebra. In particular, the vector structure of these algebra is much more tractable than the manifold structure of symmetry groups while the Lévy stability grants a given statistical universality.

  4. Scattering signatures of suspended particles: an integrated system for combining digital holography and laser diffraction.

    Science.gov (United States)

    Davies, Emlyn J; Nimmo-Smith, W Alex M; Agrawal, Yogesh C; Souza, Alejandro J

    2011-12-05

    The use of laser diffraction is now common practice for the determination of an in situ particle size distribution in the marine environment. However, various imaging techniques have shown that particles vary greatly in shape, leading to uncertainty in the response of laser diffraction instruments when subjected to this diverse range of complex particles. Here we present a novel integrated system which combines both digital in-line holography and a LISST-100 type C, to simultaneously record in-focus images of artificial and natural particles with their small-angle forward scattering signature. The system will allow for further development of a reliable alternative to Mie Theory when using laser diffraction for the in situ measurement of complex suspended particles. A more detailed knowledge of the performance of laser diffraction when subjected to the wide variety of complex particles found in the marine environment will then be possible.

  5. Graphical method for analyzing wide-angle x-ray diffraction

    Science.gov (United States)

    Chen, XiaoHui; Xue, Tao; Liu, DongBing; Yang, QingGuo; Luo, BinQiang; Li, Mu; Li, XiaoYa; Li, Jun

    2018-01-01

    Wide-angle X-ray diffraction on large-scale laser facility is a well-established experimental method, which is used to study the shock response of single crystal materials by recording X-rays diffracted from numerous lattice planes. We present a three-dimensional graphical method for extracting physical understanding from the raw diffraction data in shocked experiments. This method advances beyond the previous iterative process by turning abstract diffraction theories in shock physics into mathematic issues, providing three-dimensional visualization and quick extraction of data characteristics. The capability and versatility of the method are exhibited by identifying lattice planes for single crystal samples with different orientations and quantitatively measuring the lattice compression and rotation under dynamic loading.

  6. Wave Vector Dependent Susceptibility at T>Tc in a Dipolar Ising Ferromagnet

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Holmes, L. M:; Guggenheim, H. J.

    1974-01-01

    The wave-vector-dependent susceptibility of LiTbF4 has been investigated by means of neutron scattering. The observations show a singularity of the susceptibility near wave vector Q=0 which is characteristic of the dipolar Coulomb interaction and good agreement with theory is obtained...

  7. Towards the Development of an Automated Learning Assistant for Vector Calculus: Integration over Planar Regions

    Science.gov (United States)

    Yaacob, Yuzita; Wester, Michael; Steinberg, Stanly

    2010-01-01

    This paper presents a prototype of a computer learning assistant ILMEV (Interactive Learning-Mathematica Enhanced Vector calculus) package with the purpose of helping students to understand the theory and applications of integration in vector calculus. The main problem for students using Mathematica is to convert a textbook description of a…

  8. Robust reconstruction of time-resolved diffraction from ultrafast streak cameras

    Directory of Open Access Journals (Sweden)

    Daniel S. Badali

    2017-09-01

    Full Text Available In conjunction with ultrafast diffraction, streak cameras offer an unprecedented opportunity for recording an entire molecular movie with a single probe pulse. This is an attractive alternative to conventional pump-probe experiments and opens the door to studying irreversible dynamics. However, due to the “smearing” of the diffraction pattern across the detector, the streaking technique has thus far been limited to simple mono-crystalline samples and extreme care has been taken to avoid overlapping diffraction spots. In this article, this limitation is addressed by developing a general theory of streaking of time-dependent diffraction patterns. Understanding the underlying physics of this process leads to the development of an algorithm based on Bayesian analysis to reconstruct the time evolution of the two-dimensional diffraction pattern from a single streaked image. It is demonstrated that this approach works on diffraction peaks that overlap when streaked, which not only removes the necessity of carefully choosing the streaking direction but also extends the streaking technique to be able to study polycrystalline samples and materials with complex crystalline structures. Furthermore, it is shown that the conventional analysis of streaked diffraction can lead to erroneous interpretations of the data.

  9. Design of polarization-independent transmission fused-silica grating with high diffraction efficiency

    Science.gov (United States)

    Cheng, Yushui; Li, Chaoming; Chen, Xinrong; Yu, Jian; Tang, Yu; Wang, Rui; Xu, Haiyan; Hu, Zuyuan; Wu, Jianhong

    2018-01-01

    The high diffraction efficiency and high dispersion ability of diffraction grating plays a very important role in laser systems. Fused-silica transmission gratings not only have board band, high diffraction efficiency and high damage threshold, but also have the advantage of light path without shelter comparing to reflective gratings. In this paper, the study of polarization-independent transmission fused-silica grating is carried out, and the influence of rectangular and trapezoidal grating microstructures on the -1st diffraction efficiency of grating is analyzed. For trapezoidal groove structure, in the range of 80 to 90 degrees, the distributions of diffraction efficiency at different bottom angle are calculated and analyzed. The structure parameters of the grating are optimized by rigorous coupled wave theory. The designed grating groove density is 1440 lines/mm. The -1st diffraction efficiency of the grating is over 96% for both of TE and TM polarized waves at the Littrow angle (49.7 degrees) with the center wavelength of 1060nm. Within the bandwidth of 42nm (from 1039 to 1081nm), the -1st diffraction efficiency of the designed grating is theoretically greater than 90% for both of TE and TM polarized waves.

  10. Diffraction analysis of the microstructure of materials

    CERN Document Server

    Scardi, Paolo

    2004-01-01

    Diffraction Analysis of the Microstructure of Materials provides an overview of diffraction methods applied to the analysis of the microstructure of materials. Since crystallite size and the presence of lattice defects have a decisive influence on the properties of many engineering materials, information about this microstructure is of vital importance in developing and assessing materials for practical applications. The most powerful and usually non-destructive evaluation techniques available are X-ray and neutron diffraction. The book details, among other things, diffraction-line broadening methods for determining crystallite size and atomic-scale strain due, e.g. to dislocations, and methods for the analysis of residual (macroscale) stress. The book assumes only a basic knowledge of solid-state physics and supplies readers sufficient information to apply the methods themselves.

  11. Nonlinearity management and diffraction management for the ...

    Indian Academy of Sciences (India)

    Variational equations and partial differential equation have been simulated numerically. Analytical and numerical studies have shown that nonlinearity management and diffraction management stabilize the pulse against decay or collapse providing undisturbed propagation even for larger energies of the incident beam.

  12. Diffractive optics: design, fabrication, and test

    National Research Council Canada - National Science Library

    O'Shea, Donald C

    2004-01-01

    This book provides the reader with the broad range of materials that were discussed in a series of short courses presented at Georgia Tech on the design, fabrication, and testing of diffractive optical elements (DOEs...

  13. Final states in diffraction at HERA

    CERN Document Server

    Martínez, M

    2001-01-01

    Hadronic final states in diffractive deep inelastic scattering have been studied by the H1 and ZEUS Collaborations. Cross sections for dijet and three-jet production have been measured and compared with different model predictions.

  14. New measurements of inclusive diffraction at HERA

    CERN Document Server

    Newman, P R

    2001-01-01

    Two new diffractive measurements from HERA are described. ZEUS data on the diffractive structure function F/sub 2//sup D/ at low Q/sup 2/ constrain the transition in diffraction from the perturbative high Q /sup 2/ region to the photoproduction limit. An effective Pomeron intercept alpha P(0) is extracted from the energy dependence of the data and is compared with values from diffractive and inclusive ep interactions at lower and higher Q/sup 2/. An H1 analysis of photoproduced dijet events with low levels of hadronic activity between the jets demonstrates the presence of strongly interacting colour singlet exchanges at very high momentum transfer. The data are used to investigate the relative coupling strengths of this exchange to quarks and gluons.

  15. Introduction to electromagnetic theory

    CERN Document Server

    Owen, George E

    2003-01-01

    A direct, stimulating approach to electromagnetic theory, this text employs matrices and matrix methods for the simple development of broad theorems. The author uses vector representation throughout the book, with numerous applications of Poisson's equation and the Laplace equation (the latter occurring in both electronics and magnetic media). Contents include the electrostatics of point charges, distributions of charge, conductors and dielectrics, currents and circuits, and the Lorentz force and the magnetic field. Additional topics comprise the magnetic field of steady currents, induced ele

  16. Estimation of vector velocity

    DEFF Research Database (Denmark)

    2000-01-01

    Using a pulsed ultrasound field, the two-dimensional velocity vector can be determined with the invention. The method uses a transversally modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation. The new...... estimator automatically compensates for the axial velocity, when determining the transverse velocity by using fourth order moments rather than second order moments. The estimation is optimized by using a lag different from one in the estimation process, and noise artifacts are reduced by using averaging...... of RF samples. Further, compensation for the axial velocity can be introduced, and the velocity estimation is done at a fixed depth in tissue to reduce spatial velocity dispersion....

  17. Multistage vector (MSV) therapeutics

    Science.gov (United States)

    Wolfram, Joy; Shen, Haifa; Ferrari, Mauro

    2015-01-01

    One of the greatest challenges in the field of medicine is obtaining controlled distribution of systemically administered therapeutic agents within the body. Indeed, biological barriers such as physical compartmentalization, pressure gradients, and excretion pathways adversely affect localized delivery of drugs to pathological tissue. The diverse nature of these barriers requires the use of multifunctional drug delivery vehicles that can overcome a wide range of sequential obstacles. In this review, we explore the role of multifunctionality in nanomedicine by primarily focusing on multistage vectors (MSVs). The MSV is an example of a promising therapeutic platform that incorporates several components, including a microparticle, nanoparticles, and small molecules. In particular, these components are activated in a sequential manner in order to successively address transport barriers. PMID:26264836

  18. Soft and Hard Diffraction with CMS

    CERN Document Server

    Vilela Pereira, Antonio

    2011-01-01

    The observation of diffraction at the LHC with the CMS detector, at $\\sqrt{s}= 7$~TeV, is presented, along with a comparison of the data with the predictions of the {\\sc Pythia6}, {\\sc Pythia8} and {\\sc Phojet} generators. The observation of diffractive $W$ and $Z$ boson production is also presented, and its fraction is measured in a sample of large rapidity gap events, based on the description of the {\\sc Pompyt} generator.

  19. Tunable Beam Diffraction in Infiltrated Microstructured Fibers

    DEFF Research Database (Denmark)

    Rosberg, Christian Romer; Bennet, Francis H.; Neshev, Dragomir N.

    We experimentally study beam propagation in two dimensional photonic lattices in microstructured optical fibers infiltrated with high index liquids. We demonstrate strongly tunable beam diffraction by dynamically varying the coupling between individual lattice sites.......We experimentally study beam propagation in two dimensional photonic lattices in microstructured optical fibers infiltrated with high index liquids. We demonstrate strongly tunable beam diffraction by dynamically varying the coupling between individual lattice sites....

  20. Stationary processes with pure point diffraction

    OpenAIRE

    Lenz, Daniel; Robert V. Moody

    2011-01-01

    We consider the construction and classification of some new mathematical objects, called ergodic spatial stationary processes, on locally compact Abelian groups, which provide a natural and very general setting for studying diffraction and the famous inverse problems associated with it. In particular we can construct complete families of solutions to the inverse problem from any given pure point measure that is chosen to be the diffraction. In this case these processes can be classified by th...

  1. Vector-Tensor and Vector-Vector Decay Amplitude Analysis of B0->phi K*0

    CERN Document Server

    Aubert, B; Abrams, G S; Adye, T; Ahmed, S; Alam, M S; Albert, J; Aleksan, R; Allen, M T; Allison, J; Altenburg, D D; Andreotti, M; Angelini, C; Anulli, F; Arnaud, N; Asgeirsson, D J; Aston, D; Azzolini, V; Baak, M A; Back, J J; Baldini-Ferroli, R; Band, H R; Banerjee, Sw; Bard, D J; Barlow, N R; Barlow, R J; Barrett, M; Bartoldus, R; Batignani, G; Battaglia, M; Bauer, J M; Bechtle, P; Beck, T W; Behera, P K; Bellini, F; Benayoun, M; Benelli, G; Berger, N; Bernard, D; Berryhill, J W; Best, D S; Bettarini, S; Bettoni, D; Bevan, A J; Bhimji, W; Bhuyan, B; Bianchi, F; Biasini, M; Biesiada, J; Blanc, F; Blaylock, G; Blinov, V E; Bloom, P C; Blount, N L; Bomben, M; Bondioli, M; Bonneaud, G R; Bosisio, L; Boutigny, D; Bowerman, D A; Boyd, J T; Bozzi, C; Brandenburg, G; Brandt, T; Brau, J E; Briand, H; Brown, C M; Brown, D N; Bruinsma, M; Brunet, S; Bucci, F; Buchanan, C; Bugg, W; Bukin, A D; Bula, R; Burchat, P R; Burke, J P; Button-Shafer, J; Buzzo, A; Bóna, M; Cahn, R N; Calabrese, R; Calcaterra, A; Calderini, G; Campagnari, C; Carpinelli, M; Cartaro, C; Cavallo, N; Cavoto, G; Cenci, R; Chai, X; Chaisanguanthum, K S; Chao, M; Charles, E; Charles, M J; Chauveau, J; Chavez, C A; Chen, A; Chen, C; Chen, E; Chen, J C; Chen, S; Chen, X; Chen, X R; Cheng, B; Cheng, C H; Chia, Y M; Cibinetto, G; Clark, P J; Clarke, C K; Claus, R; Cochran, J; Coleman, J P; Contri, R; Convery, M R; Corwin, L A; Cossutti, F; Cottingham, W N; Couderc, F; Covarelli, R; Cowan, G; Cowan, R; Crawley, H B; Cremaldi, L; Cunha, A; Curry, S; Côté, D; D'Orazio, A; Dahmes, B; Dallapiccola, C; Danielson, N; Dasu, S; Datta, M; Dauncey, P D; David, P; Davier, M; Davis, C L; De Nardo, Gallieno; De Sangro, R; Del Amo-Sánchez, P; Del Buono, L; Del Re, D; Della Ricca, G; Denig, A G; Di Lodovico, F; Di Marco, E; Dingfelder, J C; Dittongo, S; Dong, L; Dorfan, J; Druzhinin, V P; Dubitzky, R S; Dubois-Felsmann, G P; Dujmic, D; Dunwoodie, W M; Dvoretskii, A; Ebert, M; Eckhart, E A; Eckmann, R; Edgar, C L; Edwards, A J; Egede, U; Eigen, G; Eisner, A M; Elmer, P; Emery, S; Ernst, J A; Eschenburg, V; Eschrich, I; Eyges, V; Fabozzi, F; Faccini, R; Fang, F; Feltresi, E; Ferrarotto, F; Ferroni, F; Field, R C; Finocchiaro, G; Flacco, C J; Flack, R L; Flächer, H U; Flood, K T; Ford, K E; Ford, W T; Forster, I J; Forti, F; Fortin, D; Foulkes, S D; Franek, B; Frey, R; Fritsch, M; Fry, J R; Fulsom, B G; Gabathuler, E; Gaidot, A; Gallo, F; Gamba, D; Gamet, R; Gan, K K; Ganzhur, S F; Gao, Y; Gary, J W; Gaspero, M; Gatto, C; Gaz, A; George, K A; Gill, M S; Giorgi, M A; Gladney, L; Glanzman, T; Godang, R; Golubev, V B; Gowdy, S J; Gradl, W; Graham, M T; Graugès-Pous, E; Grenier, P; Gritsan, A V; Grosdidier, G; Groysman, Y; Guo, Z J; Hadavand, H K; Haire, M; Halyo, V; Hamano, K; Hamel de Monchenault, G; Hamon, O; Harrison, P F; Harrison, T J; Hart, A J; Hartfiel, B L; Hast, C; Hauke, A; Hawkes, C M; Hearty, C; Held, T; Hertzbach, S S; Heusch, C A; Hill, E J; Hirschauer, J F; Hitlin, D G; Hollar, J J; Hong, T M; Honscheid, K; Hopkins, D A; Hrynóva, T; Hufnagel, D; Hulsbergen, W D; Hutchcroft, D E; Höcker, A; Igonkina, O; Innes, W R; Izen, J M; Jackson, P D; Jackson, P S; Jacobsen, R G; Jain, V; Jasper, H; Jawahery, A; Jessop, C P; Judd, D; Kadyk, J A; Kagan, H; Karyotakis, Yu; Kass, R; Kelsey, M H; Kerth, L T; Khan, A; Kim, H; Kim, P; Kirkby, D; Klose, V; Knecht, N S; Koch, H; Kolb, J A; Kolomensky, Yu G; Kovalskyi, D; Kowalewski, R V; Kozanecki, Witold; Kreisel, A; Krishnamurthy, M; Kroeger, R; Kroseberg, J; Kukartsev, G; Kutter, P E; Kyberd, P; La Vaissière, C de; Lacker, H M; Lae, C K; Lafferty, G D; Lanceri, L; Lange, D J; Lankford, A J; Latham, T E; Latour, E; Lau, Y P; Lazzaro, A; Le Diberder, F R; Lee, C L; Lees, J P; Legendre, M; Leith, D W G S; Lepeltier, V; Leruste, P; Lewandowski, B; Li Gioi, L; Li, S; Li, X; Lista, L; Liu, H; Lo Vetere, M; LoSecco, J M; Lockman, W S; Lombardo, V; Long, O; Lopes-Pegna, D; Lopez-March, N; Lou, X C; Lu, M; Luitz, S; Lund, P; Luppi, E; Lusiani, A; Lutz, A M; Lynch, G; Lynch, H L; Lü, C; Lüth, V; MacFarlane, D B; Macri, M M; Mader, W F; Majewski, S A; Malcles, J; Mallik, U; Mancinelli, G; Mandelkern, M A; Marchiori, G; Margoni, M; Marks, J; Marsiske, H; Martínez-Vidal, F; Mattison, T S; Mazur, M A; Mazzoni, M A; McKenna, J A; McMahon, T R; Mclachlin, S E; Meadows, B T; Mellado, B; Menges, W; Merkel, J; Messner, R; Meyer, N T; Meyer, W T; Mihályi, A; Mir, L M; Mishra, K; Mohanty, G B; Monge, M R; Monorchio, D; Moore, T B; Morandin, M; Morganti, M; Morganti, S; Morii, M; Muheim, F; Müller, D R; Nagel, M; Naisbit, M T; Narsky, I; Nash, J A; Nauenberg, U; Neal, H; Negrini, M; Neri, N; Nesom, G; Nicholson, H; Nikolich, M B; Nogowski, R; Nugent, I M; O'Grady, C P; Ocariz, J; Ofte, I; Olaiya, E O; Olivas, A; Olsen, J; Onuchin, A P; Orimoto, T J; Oyanguren, A; Ozcan, V E; Paar, H P; Pacetti, S; Palano, A; Palombo, F; Pan, B; Pan, Y; Panduro, W; Paoloni, E; Paolucci, P; Pappagallo, M; Park, W; Passaggio, S; Patel, P M; Patrignani, C; Patteri, P; Payne, D J; Pelizaeus, M; Perazzo, A; Perl, M; Peruzzi, I M; Peters, K; Petersen, B A; Petrella, A; Petzold, A; Piatenko, T; Piccolo, D; Piccolo, M; Piemontese, L; Pierini, M; Piredda, G; Playfer, S; Poireau, V; Polci, F; Pompili, A; Porter, F C; Posocco, M; Potter, C T; Prell, S; Prencipe, E; Prepost, R; Pripstein, M; Pruvot, S; Pulliam, T; Purohit, M V; Qi, N D; Rahatlou, S; Rahimi, A M; Rahmat, R; Rama, M; Ratcliff, B N; Raven, G; Regensburger, J J; Ricciardi, S; Richman, J D; Ritchie, J L; Rizzo, G; Roberts, D A; Robertson, A I; Robertson, S H; Robutti, E; Rodier, S; Roe, N A; Ronan, M T; Roney, J M; Rong, G; Roodman, A; Roos, L; Rosenberg, E I; Rotondo, M; Roudeau, P; Rubin, A E; Ruddick, W O; Röthel, W; Sacco, R; Saeed, M A; Safai-Tehrani, F; Saleem, M; Salnikov, A A; Salvatore, F; Sanders, D A; Santroni, A; Saremi, S; Satpathy, A; Schalk, T; Schenk, S; Schilling, C J; Schindler, R H; Schofield, K C; Schott, G; Schröder, T; Schröder, H; Schubert, J; Schubert, K R; Schumm, B A; Schune, M H; Schwiening, J; Schwierz, R; Schwitters, R F; Sciacca, C; Sciolla, G; Seiden, A; Sekula, S J; Serednyakov, S I; Serrano, J; Sharma, V; Shen, B C; Sherwood, D J; Simard, M; Simi, G; Simonetto, F; Sinev, N B; Skovpen, Yu I; Smith, A J S; Smith, J G; Snoek, H L; Snyder, A; Sobie, R J; Soffer, A; Sokoloff, M D; Solodov, E P; Spaan, B; Spanier, S M; Spitznagel, M; Spradlin, P; Steinke, M; Stelzer, J; Stocchi, A; Stoker, D P; Stroili, R; Strom, D; Strube, J; Stugu, B; Stängle, H; Su, D; Sullivan, M K; Summers, D J; Sundermann, J E; Suzuki, K; Swain, S K; Taras, P; Taylor, F; Telnov, A V; Teodorescu, L; Ter-Antonian, R; Therin, G; Thiebaux, C; Thompson, J M; Tisserand, V; Todyshev, Y K; Toki, W H; Torrence, E; Tosi, S; Touramanis, C; Ulmer, K A; Uwer, U; Van Bakel, N; Vasseur, G; Vavra, J; Vazquez, A; Verderi, M; Viaud, F B; Vitale, L; Voci, C; Voena, C; Volk, A; Wagner, A P; Wagner, S R; Wagoner, D E; Waldi, R; Walker, D; Walsh, J J; Wang, K; Wang, P; Wang, W F; Wappler, F R; Watson, A T; Weaver, M; Weinstein, A J R; Wenzel, W A; Wilden, L; Williams, D C; Williams, J C; Wilson, F F; Wilson, J R; Wilson, M G; Wilson, R J; Winklmeier, F; Wisniewski, W J; Wittgen, M; Wong, Q K; Wormser, G; Wren, A C; Wright, D H; Wright, D M; Wu, J; Wu, S L; Wulsin, H W; Xie, Y; Yamamoto, R K; Yarritu, A K; Ye, S; Yi, J I; Yi, K; Young, C C; Yu, Z; Yéche, C; Zain, S B; Zallo, A; Zeng, Q; Zghiche, A; Zhang, J; Zhang, L; Zhao, H W; Zhu, Y S; Ziegler, V; Zito, M; Çuhadar-Dönszelmann, T; al, et

    2007-01-01

    We perform an amplitude analysis of the decays B0->phi K^*_2(1430)0, phi K^*(892)0, and phi(K pi)^0_S-wave with a sample of about 384 million BBbar pairs recorded with the BABAR detector. The fractions of longitudinal polarization f_L of the vector-tensor and vector-vector decay modes are measured to be 0.853 +0.061-0.069 +-0.036 and 0.506 +-0.040 +-0.015, respectively. Overall, twelve parameters are measured for the vector-vector decay and seven parameters for the vector-tensor decay, including the branching fractions and parameters sensitive to CP-violation.

  2. Algebraic theory of numbers

    CERN Document Server

    Samuel, Pierre

    2008-01-01

    Algebraic number theory introduces students not only to new algebraic notions but also to related concepts: groups, rings, fields, ideals, quotient rings and quotient fields, homomorphisms and isomorphisms, modules, and vector spaces. Author Pierre Samuel notes that students benefit from their studies of algebraic number theory by encountering many concepts fundamental to other branches of mathematics - algebraic geometry, in particular.This book assumes a knowledge of basic algebra but supplements its teachings with brief, clear explanations of integrality, algebraic extensions of fields, Gal

  3. Crystal structure prediction supported with diffraction data

    Science.gov (United States)

    Tsujimoto, Naoto; Adachi, Daiki; Todo, Synge; Akashi, Ryosuke; Tsuneyuki, Shinji

    Atomistic computer simulation is of growing importance in the study of unidentified crystals, although prediction or determination of complicated structure is still a challenging problem due to its many degrees of freedom. Here we propose to utilize experimentally available data of powder diffraction to support and accelerate the structure simulation. In so-called direct-space methods for structure determination from powder diffraction, simplified interatomic potential energy or some other physical constraints are often used in combination with the cost function defined by diffraction data. On the other hand, we formulate a cost function called ``crystallinity'' to support simulation with accurate interatomic potential energy. Since the crystallinity here is defined as the sum of the diffraction intensities only at the peak positions detected in experiments, this method is applicable to low-quality diffraction data such as those obtained at high pressures. We apply this method to well-known polymorphs of SiO2 with up to 96 atoms in the simulation cell to find that it reproduces the correct structures efficiently with information of a very limited number of diffraction peaks.

  4. Diffraction model analysis of pion-12C elastic scattering at 800 MeV/c

    Indian Academy of Sciences (India)

    Moreover, these phenomenological analyses show that pion–12C optical potential at 800 MeV/c is attractive whereas the first-order microscopic theories strongly suggest that it should be repulsive [2,4,5]. In the diffraction model an appropriate form for the elastic S-matrix Sl is chosen and its parameters are varied to obtain ...

  5. Cobordism Obstructions to Vector Fields and a Generalization of Lin's Theorem

    DEFF Research Database (Denmark)

    Svane, Anne Marie

    Atiyah and Dupont have studied the existence of linearly independent vector fields on manifolds by means of K-theory. They obtained the complete conditions for up to three independent vector fields. In the thesis, we try to copy their approach using certain spectra related to cobordism theory. We...... that it generalizes Lin's inverse system in compact cases, while it behaves completely differently in the universal case....

  6. Transcriptional Silencing of Retroviral Vectors

    DEFF Research Database (Denmark)

    Lund, Anders Henrik; Duch, M.; Pedersen, F.S.

    1996-01-01

    Although retroviral vector systems have been found to efficiently transduce a variety of cell types in vitro, the use of vectors based on murine leukemia virus in preclinical models of somatic gene therapy has led to the identification of transcriptional silencing in vivo as an important problem...

  7. On the Witt vector Frobenius

    DEFF Research Database (Denmark)

    Davis, Christopher James; Kedlaya, Kiran

    2014-01-01

    We study the kernel and cokernel of the Frobenius map on the p-typical Witt vectors of a commutative ring, not necessarily of characteristic p. We give many equivalent conditions to surjectivity of the Frobenius map on both finite and infinite length Witt vectors. In particular, surjectivity on f...

  8. Estimation of Motion Vector Fields

    DEFF Research Database (Denmark)

    Larsen, Rasmus

    1993-01-01

    This paper presents an approach to the estimation of 2-D motion vector fields from time varying image sequences. We use a piecewise smooth model based on coupled vector/binary Markov random fields. We find the maximum a posteriori solution by simulated annealing. The algorithm generate sample...

  9. Vectors on the Basketball Court

    Science.gov (United States)

    Bergman, Daniel

    2010-01-01

    An Idea Bank published in the April/May 2009 issue of "The Science Teacher" describes an experiential physics lesson on vectors and vector addition (Brown 2009). Like its football predecessor, the basketball-based investigation presented in this Idea Bank addresses National Science Education Standards Content B, Physical Science, 9-12 (NRC 1996)…

  10. The Neural Support Vector Machine

    NARCIS (Netherlands)

    Wiering, Marco; van der Ree, Michiel; Embrechts, Mark; Stollenga, Marijn; Meijster, Arnold; Nolte, A; Schomaker, Lambertus

    2013-01-01

    This paper describes a new machine learning algorithm for regression and dimensionality reduction tasks. The Neural Support Vector Machine (NSVM) is a hybrid learning algorithm consisting of neural networks and support vector machines (SVMs). The output of the NSVM is given by SVMs that take a

  11. GPU Accelerated Vector Median Filter

    Science.gov (United States)

    Aras, Rifat; Shen, Yuzhong

    2011-01-01

    Noise reduction is an important step for most image processing tasks. For three channel color images, a widely used technique is vector median filter in which color values of pixels are treated as 3-component vectors. Vector median filters are computationally expensive; for a window size of n x n, each of the n(sup 2) vectors has to be compared with other n(sup 2) - 1 vectors in distances. General purpose computation on graphics processing units (GPUs) is the paradigm of utilizing high-performance many-core GPU architectures for computation tasks that are normally handled by CPUs. In this work. NVIDIA's Compute Unified Device Architecture (CUDA) paradigm is used to accelerate vector median filtering. which has to the best of our knowledge never been done before. The performance of GPU accelerated vector median filter is compared to that of the CPU and MPI-based versions for different image and window sizes, Initial findings of the study showed 100x improvement of performance of vector median filter implementation on GPUs over CPU implementations and further speed-up is expected after more extensive optimizations of the GPU algorithm .

  12. Blazed Grating Resonance Conditions and Diffraction Efficiency Optical Transfer Function

    KAUST Repository

    Stegenburgs, Edgars

    2017-01-08

    We introduce a general approach to study diffraction harmonics or resonances and resonance conditions for blazed reflecting gratings providing knowledge of fundamental diffraction pattern and qualitative understanding of predicting parameters for the most efficient diffraction.

  13. Waltz's Theory of Theory

    DEFF Research Database (Denmark)

    Wæver, Ole

    2009-01-01

    Kenneth N. Waltz's 1979 book, Theory of International Politics, is the most influential in the history of the discipline. It worked its effects to a large extent through raising the bar for what counted as theoretical work, in effect reshaping not only realism but rivals like liberalism and refle......Kenneth N. Waltz's 1979 book, Theory of International Politics, is the most influential in the history of the discipline. It worked its effects to a large extent through raising the bar for what counted as theoretical work, in effect reshaping not only realism but rivals like liberalism...... and reflectivism. Yet, ironically, there has been little attention to Waltz's very explicit and original arguments about the nature of theory. This article explores and explicates Waltz's theory of theory. Central attention is paid to his definition of theory as ‘a picture, mentally formed' and to the radical anti......-empiricism and anti-positivism of his position. Followers and critics alike have treated Waltzian neorealism as if it was at bottom a formal proposition about cause-effect relations. The extreme case of Waltz being so victorious in the discipline, and yet being consistently mis-interpreted on the question of theory...

  14. Vector-valued Laplace Transforms and Cauchy Problems

    CERN Document Server

    Arendt, Wolfgang; Hieber, Matthias; Neubrander, Frank

    2011-01-01

    This monograph gives a systematic account of the theory of vector-valued Laplace transforms, ranging from representation theory to Tauberian theorems. In parallel, the theory of linear Cauchy problems and semigroups of operators is developed completely in the spirit of Laplace transforms. Existence and uniqueness, regularity, approximation and above all asymptotic behaviour of solutions are studied. Diverse applications to partial differential equations are given. The book contains an introduction to the Bochner integral and several appendices on background material. It is addressed to student

  15. Emerging vector borne diseases – incidence through vectors

    Directory of Open Access Journals (Sweden)

    Sara eSavic

    2014-12-01

    Full Text Available Vector borne diseases use to be a major public health concern only in tropical and subtropical areas, but today they are an emerging threat for the continental and developed countries also. Nowdays, in intercontinetal countries, there is a struggle with emerging diseases which have found their way to appear through vectors. Vector borne zoonotic diseases occur when vectors, animal hosts, climate conditions, pathogens and susceptible human population exist at the same time, at the same place. Global climate change is predicted to lead to an increase in vector borne infectious diseases and disease outbreaks. It could affect the range and popultion of pathogens, host and vectors, transmission season, etc. Reliable surveilance for diseases that are most likely to emerge is required. Canine vector borne diseases represent a complex group of diseases including anaplasmosis, babesiosis, bartonellosis, borreliosis, dirofilariosis, erlichiosis, leishmaniosis. Some of these diseases cause serious clinical symptoms in dogs and some of them have a zoonotic potential with an effect to public health. It is expected from veterinarians in coordination with medical doctors to play a fudamental role at primeraly prevention and then treatment of vector borne diseases in dogs. The One Health concept has to be integrated into the struggle against emerging diseases.During a four year period, from 2009-2013, a total number of 551 dog samples were analysed for vector borne diseases (borreliosis, babesiosis, erlichiosis, anaplasmosis, dirofilariosis and leishmaniasis in routine laboratory work. The analysis were done by serological tests – ELISA for borreliosis, dirofilariosis and leishmaniasis, modified Knott test for dirofilariosis and blood smear for babesiosis, erlichiosis and anaplasmosis. This number of samples represented 75% of total number of samples that were sent for analysis for different diseases in dogs. Annually, on avarege more then half of the samples

  16. Flatland Photonics: Circumventing Diffraction with Planar Plasmonic Architectures

    Science.gov (United States)

    Dionne, Jennifer Anne

    On subwavelength scales, photon-matter interactions are limited by diffraction. The diffraction limit restricts the size of optical devices and the resolution of conventional microscopes to wavelength-scale dimensions, severely hampering our ability to control and probe subwavelength-scale optical phenomena. Circumventing diffraction is now a principle focus of integrated nanophotonics. Surface plasmons provide a particularly promising approach to sub-diffraction-limited photonics. Surface plasmons are hybrid electron-photon modes confined to the interface between conductors and transparent materials. Combining the high localization of electronic waves with the propagation properties of optical waves, plasmons can achieve extremely small mode wavelengths and large local electromagnetic field intensities. Through their unique dispersion, surface plasmons provide access to an enormous phase space of refractive indices and propagation constants that can be readily tuned with material or geometry. In this thesis, we explore both the theory and applications of dispersion in planar plasmonic architectures. Particular attention is given to the modes of metallic core and plasmon slot waveguides, which can span positive, near-zero, and even negative indices. We demonstrate how such basic plasmonic geometries can be used to develop a suite of passive and active plasmonic components, including subwavelength waveguides, color filters, negative index metamaterials, and optical MOS field effect modulators. Positive index modes are probed by near- and far-field techniques, revealing plasmon wavelengths as small as one-tenth of the excitation wavelength. Negative index modes are characterized through direct visualization of negative refraction. By fabricating prisms comprised of gold, silicon nitride, and silver multilayers, we achieve the first experimental demonstration of a negative index material at visible frequencies, with potential applications for sub-diffraction

  17. Time Domain Diffraction by Composite Structures

    Science.gov (United States)

    Riccio, Giovanni; Frongillo, Marcello

    2017-04-01

    Time domain (TD) diffraction problems are receiving great attention because of the widespread use of ultra wide band (UWB) communication and radar systems. It is commonly accepted that, due to the large bandwidth of the UWB signals, the analysis of the wave propagation mechanisms in the TD framework is preferable to the frequency domain (FD) data processing. Furthermore, the analysis of transient scattering phenomena is also of importance for predicting the effects of electromagnetic pulses on civil structures. Diffraction in the TD framework represents a challenging problem and numerical discretization techniques can be used to support research and industry activities. Unfortunately, these methods become rapidly intractable when considering excitation pulses with high frequency content. This contribution deals with the TD diffraction phenomenon related to composite structures containing a dielectric wedge with arbitrary apex angle when illuminated by a plane wave. The approach is the same used in [1]-[3]. The transient diffracted field originated by an arbitrary function plane wave is evaluated via a convolution integral involving the TD diffraction coefficients, which are determined in closed form starting from the knowledge of the corresponding FD counterparts. In particular, the inverse Laplace transform is applied to the FD Uniform Asymptotic Physical Optics (FD-UAPO) diffraction coefficients available for the internal region of the structure and the surrounding space. For each observation domain, the FD-UAPO expressions are obtained by considering electric and magnetic equivalent PO surface currents located on the interfaces. The surface radiation integrals using these sources is assumed as starting point and manipulated for obtaining integrals able to be solved by means of the Steepest Descent Method and the Multiplicative Method. [1] G. Gennarelli and G. Riccio, "Time domain diffraction by a right-angled penetrable wedge," IEEE Trans. Antennas Propag., Vol

  18. Functional analysis theory and applications

    CERN Document Server

    Edwards, RE

    2011-01-01

    ""The book contains an enormous amount of information - mathematical, bibliographical and historical - interwoven with some outstanding heuristic discussions."" - Mathematical Reviews.In this massive graduate-level study, Emeritus Professor Edwards (Australian National University, Canberra) presents a balanced account of both the abstract theory and the applications of linear functional analysis. Written for readers with a basic knowledge of set theory, general topology, and vector spaces, the book includes an abundance of carefully chosen illustrative examples and excellent exercises at the

  19. Feasibility study neutron diffraction at IRI

    Energy Technology Data Exchange (ETDEWEB)

    Haan, V.O. de

    1995-06-01

    Although neutron diffraction is a basic and relatively simple technique and should be available at a neutron source, it is not possible to perform neutron diffraction measurements at IRI at this moment. Until recently a neutron diffractometer with a relatively small flux at the sample position and a relaxed resolution (designed for liquid diffraction) was operated at IRI. Due to the modest neutron source intensity and the relatively old design (flat monochromator and single detector) this diffractometer was outdated. However, at a contemporary reactor source an instrument to perform neutron diffraction experiments cannot be missed. This study shows that thanks to recent developments in neutron diffraction optics it is possible to increase the flux, to enhance the resolution and to get a better flexibility. If also the number of detectors is increased or a position-sensitive detector is used to performance can be increased at least a thousand fold. A preliminary design is given to indicate how this gain can be realized. (orig.).

  20. Quantitative phase analysis by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Hee; Song, Su Ho; Lee, Jin Ho; Shim, Hae Seop [Korea Atomic Energy Research Institute, Taejon (Korea)

    1999-06-01

    This study is to apply quantitative phase analysis (QPA) by neutron diffraction to the round robin samples provided by the International Union of Crystallography(IUCr). We measured neutron diffraction patterns for mixed samples which have several different weight percentages and their unique characteristic features. Neutron diffraction method has been known to be superior to its complementary methods such as X-ray or Synchrotron, but it is still accepted as highly reliable under limited conditions or samples. Neutron diffraction has strong capability especially on oxides due to its scattering cross-section of the oxygen and it can become a more strong tool for analysis on the industrial materials with this quantitative phase analysis techniques. By doing this study, we hope not only to do one of instrument performance tests on our HRPD but also to improve our ability on the analysis of neutron diffraction data by comparing our QPA results with others from any advanced reactor facilities. 14 refs., 4 figs., 6 tabs. (Author)

  1. Surface diffusion studies by optical diffraction techniques

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Xu -Dong [Univ. of California, Berkeley, CA (United States)

    1992-11-01

    The newly developed optical techniques have been combined with either second harmonic (SH) diffraction or linear diffraction off a monolayer adsorbate grating for surface diffusion measurement. Anisotropy of surface diffusion of CO on Ni(l10) was used as a demonstration for the second harmonic dim reaction method. The linear diffraction method, which possesses a much higher sensitivity than the SH diffraction method, was employed to study the effect of adsorbate-adsorbate interaction on CO diffusion on Ni(l10) surface. Results showed that only the short range direct CO-CO orbital overlapping interaction influences CO diffusion but not the long range dipole-dipole and CO-NI-CO interactions. Effects of impurities and defects on surface diffusion were further explored by using linear diffraction method on CO/Ni(110) system. It was found that a few percent S impurity can alter the CO diffusion barrier height to a much higher value through changing the Ni(110) surface. The point defects of Ni(l10) surface seem to speed up CO diffusion significantly. A mechanism with long jumps over multiple lattice distance initiated by CO filled vacancy is proposed to explain the observed defect effect.

  2. Ultrafast Kikuchi diffraction: nanoscale stress-strain dynamics of wave-guiding structures.

    Science.gov (United States)

    Yurtsever, Aycan; Schaefer, Sascha; Zewail, Ahmed H

    2012-07-11

    Complex structural dynamics at the nanoscale requires sufficiently small probes to be visualized. In conventional imaging using electron microscopy, the dimension of the probe is large enough to cause averaging over the structures present. However, by converging ultrafast electron bunches, it is possible to select a single nanoscale structure and study the dynamics, either in the image or using electron diffraction. Moreover, the span of incident wave vectors in a convergent beam enables sensitivity levels and information contents beyond those of parallel-beam illumination with a single wave vector Bragg diffraction. Here, we report the observation of propagating strain waves using ultrafast Kikuchi diffraction from nanoscale volumes within a wedge-shaped silicon single crystal. It is found that the heterogeneity of the strain in the lateral direction is only 100 nm. The transient elastic wave gives rise to a coherent oscillation with a period of 30 ps and with an envelope that has a width of 140 ps. The origin of this elastic deformation is theoretically examined using finite element analysis; it is identified as propagating shear waves. The wedge-shaped structure, unlike parallel-plate structure, is the key behind the traveling nature of the waves as its angle permits "transverse" propagation; the parallel-plate structure only exhibits the "longitudinal" motion. The studies reported suggest extension to a range of applications for nanostructures of different shapes and for exploring their ultrafast eigen-modes of stress-strain profiles.

  3. Dynamical analysis for a vector-like dark energy

    Science.gov (United States)

    Landim, Ricardo C. G.

    2016-09-01

    In this paper we perform a dynamical analysis for a vector field as a candidate for the dark energy, in the presence of a barotropic fluid. The vector is one component of the so-called cosmic triad, which is a set of three identical copies of an abelian field pointing mutually in orthogonal directions. In order to generalize the analysis, we also assumed the interaction between dark energy and the barotropic fluid, with a phenomenological coupling. Both matter and dark energy eras can be successfully described by the critical points, indicating that the dynamical system theory is a viable tool to analyze asymptotic states of such cosmological models.

  4. Dynamical analysis for a vector-like dark energy

    Energy Technology Data Exchange (ETDEWEB)

    Landim, Ricardo C.G. [Instituto de Fisica, Universidade de Sao Paulo, Departamento de Fisica-Matematica, Sao Paulo, SP (Brazil)

    2016-09-15

    In this paper we perform a dynamical analysis for a vector field as a candidate for the dark energy, in the presence of a barotropic fluid. The vector is one component of the so-called cosmic triad, which is a set of three identical copies of an abelian field pointing mutually in orthogonal directions. In order to generalize the analysis, we also assumed the interaction between dark energy and the barotropic fluid, with a phenomenological coupling. Both matter and dark energy eras can be successfully described by the critical points, indicating that the dynamical system theory is a viable tool to analyze asymptotic states of such cosmological models. (orig.)

  5. Diffraction of convergent spherical waves with all possible polarization states using the Luneburg integral method.

    Science.gov (United States)

    Carretero, Luis; Acebal, Pablo; Blaya, Salvador

    2013-04-01

    We present a complete electromagnetic study, which includes electric, magnetic, and Poynting vector fields of diffracted convergent spherical waves under all possible polarization states compatible with Maxwell's equations. Exit pupil boundary conditions for these polarizations were obtained by means of Hertz potentials. Using these boundary conditions, two-dimensional Luneburg diffraction integrals for the three components of electric and magnetic fields were formulated, and after some approximations, we showed that the complete electromagnetic description of the inhomogeneous polarization states of spherical waves is reduced to the knowledge of seven one-dimensional integrals. The consistency of the method was tested by comparison with other previously reported methods for linearly polarized (LP), TE, and TM polarizations, while the versatility of the method was showed with the study of nonstandard polarization states, for example, that resulting from the superposition of TE and TM dephased spherical waves, which shows a helicoidal behavior of the Poynting vector at the focalization region, or the inhomogeneous LP state that exhibits a ring structure for the Poynting vector at the focal plane.

  6. Stable piecewise polynomial vector fields

    Directory of Open Access Journals (Sweden)

    Claudio Pessoa

    2012-09-01

    Full Text Available Let $N={y>0}$ and $S={y<0}$ be the semi-planes of $mathbb{R}^2$ having as common boundary the line $D={y=0}$. Let $X$ and $Y$ be polynomial vector fields defined in $N$ and $S$, respectively, leading to a discontinuous piecewise polynomial vector field $Z=(X,Y$. This work pursues the stability and the transition analysis of solutions of $Z$ between $N$ and $S$, started by Filippov (1988 and Kozlova (1984 and reformulated by Sotomayor-Teixeira (1995 in terms of the regularization method. This method consists in analyzing a one parameter family of continuous vector fields $Z_{epsilon}$, defined by averaging $X$ and $Y$. This family approaches $Z$ when the parameter goes to zero. The results of Sotomayor-Teixeira and Sotomayor-Machado (2002 providing conditions on $(X,Y$ for the regularized vector fields to be structurally stable on planar compact connected regions are extended to discontinuous piecewise polynomial vector fields on $mathbb{R}^2$. Pertinent genericity results for vector fields satisfying the above stability conditions are also extended to the present case. A procedure for the study of discontinuous piecewise vector fields at infinity through a compactification is proposed here.

  7. Chikungunya Virus–Vector Interactions

    Directory of Open Access Journals (Sweden)

    Lark L. Coffey

    2014-11-01

    Full Text Available Chikungunya virus (CHIKV is a mosquito-borne alphavirus that causes chikungunya fever, a severe, debilitating disease that often produces chronic arthralgia. Since 2004, CHIKV has emerged in Africa, Indian Ocean islands, Asia, Europe, and the Americas, causing millions of human infections. Central to understanding CHIKV emergence is knowledge of the natural ecology of transmission and vector infection dynamics. This review presents current understanding of CHIKV infection dynamics in mosquito vectors and its relationship to human disease emergence. The following topics are reviewed: CHIKV infection and vector life history traits including transmission cycles, genetic origins, distribution, emergence and spread, dispersal, vector competence, vector immunity and microbial interactions, and co-infection by CHIKV and other arboviruses. The genetics of vector susceptibility and host range changes, population heterogeneity and selection for the fittest viral genomes, dual host cycling and its impact on CHIKV adaptation, viral bottlenecks and intrahost diversity, and adaptive constraints on CHIKV evolution are also discussed. The potential for CHIKV re-emergence and expansion into new areas and prospects for prevention via vector control are also briefly reviewed.

  8. Chikungunya Virus–Vector Interactions

    Science.gov (United States)

    Coffey, Lark L.; Failloux, Anna-Bella; Weaver, Scott C.

    2014-01-01

    Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes chikungunya fever, a severe, debilitating disease that often produces chronic arthralgia. Since 2004, CHIKV has emerged in Africa, Indian Ocean islands, Asia, Europe, and the Americas, causing millions of human infections. Central to understanding CHIKV emergence is knowledge of the natural ecology of transmission and vector infection dynamics. This review presents current understanding of CHIKV infection dynamics in mosquito vectors and its relationship to human disease emergence. The following topics are reviewed: CHIKV infection and vector life history traits including transmission cycles, genetic origins, distribution, emergence and spread, dispersal, vector competence, vector immunity and microbial interactions, and co-infection by CHIKV and other arboviruses. The genetics of vector susceptibility and host range changes, population heterogeneity and selection for the fittest viral genomes, dual host cycling and its impact on CHIKV adaptation, viral bottlenecks and intrahost diversity, and adaptive constraints on CHIKV evolution are also discussed. The potential for CHIKV re-emergence and expansion into new areas and prospects for prevention via vector control are also briefly reviewed. PMID:25421891

  9. Fraunhofer diffraction of electromagnetic radiation by finite periodic structures with regular or irregular overall shapes.

    Science.gov (United States)

    Xu, Yu-Lin

    2015-01-01

    Based on an essentially different theoretical foundation than common classical diffraction theories that remain in extensive use, this paper discusses from a fresh perspective the theoretical interpretation and prediction of the far-field diffraction of a plane monochromatic wave by a finite periodic array (PA) of identical obstacles. The theoretical treatment rests on the PA extension of the rigorous generalized multiparticle Mie solution (GMM). The truncated periodic structures may have an irregular overall shape with an arbitrary spatial orientation with respect to the incident beam. It is shown that the overall shape and intrinsic geometrical structure of a finite PA play a decisive role in giving rise to an associated far-field diffraction pattern. It is also shown that, when the physical dimensions of individual component units are much smaller than the incident wavelength, the extracted diffraction pattern of a densely packed PA of such small volumes in forward directions exhibits the distinct features predicted from classical diffraction theories for an aperture with the same shape as the overall finite PA. Several typical examples are presented, including two complementary arrays used in the specific discussion concerning Babinet's principle. There are brief preliminary discussions on some fundamental concepts in connection with the involved theoretical basis and on potential further development and application of the present GMM-PA approach.

  10. Electromagnetic diffraction radiation of a subwavelength-hole array excited by an electron beam.

    Science.gov (United States)

    Liu, Shenggang; Hu, Min; Zhang, Yaxin; Li, Yuebao; Zhong, Renbin

    2009-09-01

    This paper explores the physics of the electromagnetic diffraction radiation of a subwavelength holes array excited by a set of evanescent waves generated by a line charge of electron beam moving parallel to the array. Activated by a uniformly moving line charge, numerous physical phenomena occur such as the diffraction radiation on both sides of the array as well as the electromagnetic penetration or transmission below or above the cut-off through the holes. As a result the subwavelength holes array becomes a radiation array. Making use of the integral equation with relevant Green's functions, an analytical theory for such a radiation system is built up. The results of the numerical calculations based on the theory agree well with that obtained by the computer simulation. The relation among the effective surface plasmon wave, the electromagnetic penetration or transmission of the holes and the diffraction radiation is revealed. The energy dependence of and the influence of the hole thickness on the diffraction radiation and the electromagnetic penetration or transmission are investigated in detail. Therefore, a distinct diffraction radiation phenomenon is discovered.

  11. Soft and Hard Diffraction at CMS

    CERN Document Server

    Sanchez, Ann - Karin

    2011-01-01

    The observation of a diffractive signal dominated by the inclusive single diffractive dissociation reaction pp -> pX is presented. The analysis is based on a fraction of the data collected by the CMS experiment in 2010 and corresponds to an integrated luminosity of 10, 0.4 and 20 mub-1 at 0.9, 2.36 and 7 TeV, respectively. Detector level distributions are compared to fully simulated and reconstructed Monte Carlo predictions obtained with the PYTHIA6, PHOJET and PYTHIA8 generators. The observation of the production of W and Z bosons at the LHC in pp collision events with a large rapidity gap is presented. Using data collected by the CMS experiment in 2010, corresponding to an integrated luminosity of 35 pb-1, a detailed study of the event structure and the energy distribution in the forward region of w and Z events is presented. These contain also event samples which are dominated by diffractive interactions.

  12. Diffraction and rapidity gap measurements with ATLAS

    CERN Document Server

    Kus, V; The ATLAS collaboration

    2014-01-01

    Two diffraction related measurements of proton-proton collisions in the ATLAS experiment of the Large Hadron Collider at $\\surd s$ = 7 TeV centre-of-mass energy are reviewed. First of them is a fraction of diffractive contribution to the inelastic cross section. Second measurement is dedicated to the identification of Single Diffractive interactions with large pseudo-rapidity gaps using early 2010 data sample of integrated luminosity 7.1 $\\mu b^{-1}$. Differential cross sections of largest forward areas of the ATLAS detector starting at its most forward edges $\\eta = \\pm 4.9$ without any particle activity above different transverse momentum thresholds are measured. Results are compared to several distinctive Monte Carlo models resulting in constraint of Pomeron intercept value in triple Pomeron based approach. Furthermore, proton-proton interactions in small pseudo-rapidity gap region test qualitatively a description of different hadronisation models as well as statistical fluctuations during hadronisation pr...

  13. Diffraction pattern study for cell type identification.

    Science.gov (United States)

    Mihailescu, M; Costescu, J

    2012-01-16

    This paper presents our study regarding diffracted intensity distribution in Fresnel and Fraunhofer approximation from different cell types. Starting from experimental information obtained through digital holographic microscopy, we modeled the cell shapes as oblate spheroids and built their phase-only transmission functions. In Fresnel approximation, the experimental and numerical diffraction patterns from mature and immature red blood cells have complementary central intensity values at different distances. The Fraunhofer diffraction patterns of deformed red blood cells were processed in the reciprocal space where, the isoamplitude curves were formed independently for each degree of cell deformation present within every sample; the values on each separate isoamplitude curve are proportional with the percentage of the respective cell type within the sample.

  14. Small angle electron diffraction and deflection

    Directory of Open Access Journals (Sweden)

    T. Koyama

    2012-03-01

    Full Text Available Electron optical system is constructed in order to obtain small angle diffraction and Lorentz deflection of electrons at the order of down to 10-6 radian in the reciprocal space. Long-distance camera length up to 3000 m is achieved in a conventional transmission electron microscope with LaB6 thermal emission type. The diffraction pattern at 5 × 10-6 radian is presented in a carbon replica grating with 500 nm lattice spacing while the magnetic deflection pattern at 2 × 10-5 radian is exhibited in Permalloy elements. A simultaneous recording of electron diffraction and Lorentz deflection is also demonstrated in 180 degree striped magnetic domains of La0.825Sr0.175MnO3.

  15. Immobilizing Biomolecules Near the Diffraction Limit

    DEFF Research Database (Denmark)

    Skovsen, Esben; Petersen, Maria Teresa Neves; Gennaro, Ane Kold Di

    2009-01-01

    Our group has previously shown that biomolecules containing disulfide bridges in close proximity to aromatic residues can be immobilized, through covalent bonds, onto thiol derivatized surfaces upon UV excitation of the aromatic residue(s). We have also previously shown that our new technology can...... be used to print arrays of biomolecules and to immobilize biomolecules according to any specific pattern on a planar substrates with micrometer scale resolution. In this paper we show that we can immobilize proteins according to diffraction patterns of UV light. We also show that the feature size...... of the immobilized patterns can be as small as the diffraction limit for the excitation light, and that the immobilized patterns correspond to the diffraction pattern used to generate it. The flexibility of this new technology will in principle make it possible to create any pattern of biomolecules onto a substrate...

  16. Random point sets and their diffraction

    Science.gov (United States)

    Baake, Michael; Kösters, Holger

    2011-07-01

    The diffraction of various random subsets of the integer lattice ℤ d , such as the coin tossing and related systems, are well understood. Here, we go one important step beyond and consider random point sets in ℝ d . We present several systems with an effective stochastic interaction that still allow for explicit calculations of the autocorrelation and the diffraction measure. We concentrate on one-dimensional examples for illustrative purposes, and briefly indicate possible generalisations to higher dimensions. In particular, we discuss the stationary Poisson process in ℝ d and the renewal process on the line. The latter permits a unified approach to a rather large class of one-dimensional structures, including random tilings. Moreover, we present some stationary point processes that are derived from the classical random matrix ensembles as introduced in the pioneering work of Dyson and Ginibre. Their reconsideration from the diffraction point of view improves the intuition on systems with randomness and mixed spectra.

  17. Diffractive elements performance in chromatic confocal microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Garzon, J; Duque, D; Alean, A; Toledo, M [Grupo de Optica y EspectroscopIa, Centro de Ciencia Basica, Universidad Pontificia Bolivariana. Medellin (Colombia); Meneses, J [Laboratorio de Optica y Tratamiento de Senales, Instituto de Fisica, Universidad Industrial de Santander, Bucaramanga (Colombia); Gharbi, T, E-mail: jgarzonr10@une.net.co [Laboratoire d' Optique P. M. Duffieux, UMR-6603 CNR/Universite de Franche-Comte. 16 route de Gray, 25030 Besancon Cedex (France)

    2011-01-01

    The Confocal Laser Scanning Microscopy (CLSM) has been widely used in the semiconductor industry and biomedicine because of its depth discrimination capability. Subsequent to this technique has been developed in recent years Chromatic Confocal Microscopy. This method retains the same principle of confocal and offers the added advantage of removing the axial movement of the moving system. This advantage is usually accomplished with an optical element that generates a longitudinal chromatic aberration and a coding system that relates the axial position of each point of the sample with the wavelength that is focused on each. The present paper shows the performance of compact chromatic confocal microscope when some different diffractive elements are used for generation of longitudinal chromatic aberration. Diffractive elements, according to the process and manufacturing parameters, may have different diffraction efficiency and focus a specific wavelength in a specific focal position. The performance assessment is carried out with various light sources which exhibit an incoherent behaviour and a broad spectral width.

  18. Diffraction manipulation by four-wave mixing.

    Science.gov (United States)

    Katzir, Itay; Ron, Amiram; Firstenberg, Ofer

    2015-03-09

    We suggest a scheme to manipulate paraxial diffraction by utilizing the dependency of a four-wave mixing process on the relative angle between the light fields. A microscopic model for four-wave mixing in a Λ-type level structure is introduced and compared to recent experimental data. We show that images with feature size as low as 10 μm can propagate with very little or even negative diffraction. The mechanism is completely different from that conserving the shape of spatial solitons in nonlinear media, as here diffraction is suppressed for arbitrary spatial profiles. At the same time, the gain inherent to the nonlinear process prevents loss and allows for operating at high optical depths. Our scheme does not rely on atomic motion and is thus applicable to both gaseous and solid media.

  19. Electron backscatter diffraction in materials characterization

    Directory of Open Access Journals (Sweden)

    Dejan Stojakovic

    2012-03-01

    Full Text Available Electron Back-Scatter Diffraction (EBSD is a powerful technique that captures electron diffraction patterns from crystals, constituents of material. Captured patterns can then be used to determine grain morphology, crystallographic orientation and chemistry of present phases, which provide complete characterization of microstructure and strong correlation to both properties and performance of materials. Key milestones related to technological developments of EBSD technique have been outlined along with possible applications using modern EBSD system. Principles of crystal diffraction with description of crystallographic orientation, orientation determination and phase identification have been described. Image quality, resolution and speed, and system calibration have also been discussed. Sample preparation methods were reviewed and EBSD application in conjunction with other characterization techniques on a variety of materials has been presented for several case studies. In summary, an outlook for EBSD technique was provided.

  20. Emerging Vector-Borne Diseases - Incidence through Vectors.

    Science.gov (United States)

    Savić, Sara; Vidić, Branka; Grgić, Zivoslav; Potkonjak, Aleksandar; Spasojevic, Ljubica

    2014-01-01

    Vector-borne diseases use to be a major public health concern only in tropical and subtropical areas, but today they are an emerging threat for the continental and developed countries also. Nowadays, in intercontinental countries, there is a struggle with emerging diseases, which have found their way to appear through vectors. Vector-borne zoonotic diseases occur when vectors, animal hosts, climate conditions, pathogens, and susceptible human population exist at the same time, at the same place. Global climate change is predicted to lead to an increase in vector-borne infectious diseases and disease outbreaks. It could affect the range and population of pathogens, host and vectors, transmission season, etc. Reliable surveillance for diseases that are most likely to emerge is required. Canine vector-borne diseases represent a complex group of diseases including anaplasmosis, babesiosis, bartonellosis, borreliosis, dirofilariosis, ehrlichiosis, and leishmaniosis. Some of these diseases cause serious clinical symptoms in dogs and some of them have a zoonotic potential with an effect to public health. It is expected from veterinarians in coordination with medical doctors to play a fundamental role at primarily prevention and then treatment of vector-borne diseases in dogs. The One Health concept has to be integrated into the struggle against emerging diseases. During a 4-year period, from 2009 to 2013, a total number of 551 dog samples were analyzed for vector-borne diseases (borreliosis, babesiosis, ehrlichiosis, anaplasmosis, dirofilariosis, and leishmaniasis) in routine laboratory work. The analysis was done by serological tests - ELISA for borreliosis, dirofilariosis, and leishmaniasis, modified Knott test for dirofilariosis, and blood smear for babesiosis, ehrlichiosis, and anaplasmosis. This number of samples represented 75% of total number of samples that were sent for analysis for different diseases in dogs. Annually, on average more then half of the samples

  1. Diffracted optical vortices by an angular aperture

    Science.gov (United States)

    López H., Paula A.; Reyes Q., Zayda P.; Guzmán, Ángela M.; Torres M., Yezid; Mendoza C., Jesús H.

    2017-08-01

    The measurement of the topological charge of laser beams with orbital angular momentum (OAM) is key to many applications like deciphering information encoded in several channels. Current techniques useful for that purpose are interferometry, diffraction through different poligonal apertures like triangular or pentagonal and, azimuthal and radial decomposition. A less explored issue is the diffraction of OAM beams through circular sectors. Jack et al. studied the angular diffraction of Gaussian beams (whose OAM is null) through a circular sector. By means of a Fourier transform of the truncated Gaussian beam they showed that the orbital angular momentum spectrum of the transmitted beam has a sinc-shaped envelope centered at zero orbital angular momentum, the width of which increases as the central angle of the circular sector decreases. We analyze here the spectrum of a laser beam with integer OAM that has been diffracted by a circular sector. We present results for circular sectors of different central angles. For circular π-sector, we also study the influence of the transmittance in the OAM spectra of the transmitted beam, using straight borders of nanometric thin films of titanium oxide with different thicknesses. We use a spatial light modulator with a fork hologram placed on to generate the incoming OAM beam and measure the evolution of the intensity profile of the diffracted beam as it propagates away from the circular sector. The spectra of the diffracted OAM beams are shown numerically and experimentally to have a sinc shaped envelope centered at the OAM value of the incoming OAM wave.

  2. Vector control of induction machines

    CERN Document Server

    Robyns, Benoit

    2012-01-01

    After a brief introduction to the main law of physics and fundamental concepts inherent in electromechanical conversion, ""Vector Control of Induction Machines"" introduces the standard mathematical models for induction machines - whichever rotor technology is used - as well as several squirrel-cage induction machine vector-control strategies. The use of causal ordering graphs allows systematization of the design stage, as well as standardization of the structure of control devices. ""Vector Control of Induction Machines"" suggests a unique approach aimed at reducing parameter sensitivity for

  3. Vector boson scattering at CLIC

    Energy Technology Data Exchange (ETDEWEB)

    Kilian, Wolfgang; Fleper, Christian [Department Physik, Universitaet Siegen, 57068 Siegen (Germany); Reuter, Juergen [DESY Theory Group, 22603 Hamburg (Germany); Sekulla, Marco [Institut fuer Theoretische Physik, Karlsruher Institut fuer Technologie, 76131 Karlsruhe (Germany)

    2016-07-01

    Linear colliders operating in a range of multiple TeV are able to investigate the details of vector boson scattering and electroweak symmetry breaking. We calculate cross sections with the Monte Carlo generator WHIZARD for vector boson scattering processes at the future linear e{sup +} e{sup -} collider CLIC. By finding suitable cuts, the vector boson scattering signal processes are isolated from the background. Finally, we are able to determine exclusion sensitivities on the non-Standard Model parameters of the relevant dimension eight operators.

  4. Classical system underlying a diffracting quantum billiard

    Science.gov (United States)

    Jain, Manan

    2018-02-01

    For a point scatterer placed slightly off the centre of a circular enclosure, rays are found which vividly exhibit the effect of diffraction. The Schrödinger equation was mapped in the complex plane by employing a fractional linear transformation which brings the point scatterer to the centre. But the mass of the particle becomes a function of space coordinates, bearing anisotropy. For the transformed problem, the corresponding classical Hamiltonian is written and solved with Snell's laws on the boundary. The solutions of the Hamilton's equations thus found constitute, in fact, the ray-manifold underlying the diffraction at the level of the wave description.

  5. Small angle electron diffraction and deflection

    OpenAIRE

    T. Koyama; K. Takayanagi; Y. Togawa; S. Mori; K. Harada

    2012-01-01

    Electron optical system is constructed in order to obtain small angle diffraction and Lorentz deflection of electrons at the order of down to 10-6 radian in the reciprocal space. Long-distance camera length up to 3000 m is achieved in a conventional transmission electron microscope with LaB6 thermal emission type. The diffraction pattern at 5 × 10-6 radian is presented in a carbon replica grating with 500 nm lattice spacing while the magnetic deflection pattern at 2 × 10-5 radian is exhibited...

  6. Quantum interference fringes beating the diffraction limit

    OpenAIRE

    Kawabe, Yoshio; Fujiwara, Hideki; Okamoto, Ryo; Sasaki, Keiji; Takeuchi, Shigeki

    2007-01-01

    Spatially formed two-photon interference fringes with fringe periods smaller than the diffraction limit are demonstrated. In the experiment, a fringe formed by two-photon NOON states with wavelength λ=702.2 nm is observed using a specially developed near-field scanning optical microscope probe and two-photon detection setup. The observed fringe period of 328.2 nm is well below the diffraction limit (351 nm = λ/2). Another experiment with a path-length difference larger than the coherent lengt...

  7. Quantum interference fringes beating the diffraction limit.

    Science.gov (United States)

    Kawabe, Yoshio; Fujiwara, Hideki; Okamoto, Ryo; Sasaki, Keiji; Takeuchi, Shigeki

    2007-10-17

    Spatially formed two-photon interference fringes with fringe periods smaller than the diffraction limit are demonstrated. In the experiment, a fringe formed by two-photon NOON states with wavelength lambda=702.2 nm is observed using a specially developed near-field scanning optical microscope probe and two-photon detection setup. The observed fringe period of 328.2 nm is well below the diffraction limit (351 nm = lambda /2). Another experiment with a path-length difference larger than the coherent length of photons confirms that the observed fringe is due to two-photon interference.

  8. Optically Patternable Metamaterial Below Diffraction Limit.

    Science.gov (United States)

    Lee, Youngseop; Park, Sang-Gil; Yoo, SeokJae; Kang, Minhee; Jeon, Sang Chul; Kim, Young-Su; Park, Q-Han; Jeong, Ki-Hun

    2017-06-07

    We report an optically patternable metamaterial (OPM) for ultraviolet nanolithography below the diffraction limit. The OPM features monolayered silver nanoislands embedded within a photosensitive polymer by using spin-coating of an ultrathin polymer, oblique angle deposition, and solid-state embedment of silver nanoislands. This unique configuration simultaneously exhibits both negative effective permittivity and high image contrast in the ultraviolet range, which enables the surface plasmon excitation for the clear photolithographic definition of minimum feature size of 70 nm (≲ λ/5) beyond the near-field zone. This new metamaterial provides a new class of photoresist for ultraviolet nanolithography below the diffraction limit.

  9. Lithographic Performance Enhancement Using Dummy Diffraction Mask

    Science.gov (United States)

    Yoo, Hyung Joun; Oh, Yong-Ho; Park, Byung-Sun; Choi, Sang Soo; Jeon, Young Jin; Lee, Choochon; Park, Sin-Chong

    1993-12-01

    The basic lithographic characteristics of the dummy diffraction mask which has two (dummy and main) mask layers, are investigated by simulation and experiment. The basic principle and theoretical details of the dummy diffraction mask are explained. Influences on the aerial image by the gap size and misorientation between two mask layers and by the nonideal phase grating, are simulated. Also, results of the lithographic performances for the simple patterns (line/space, isolated line, isolated space) and the complex patterns (V-shape active pattern in dynamic random access memory core cell) are presented.

  10. Data processing method for neutron diffraction experiments

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Palomino, L.A. [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Centro Atomico Bariloche, Instituto Balseiro, Comision Nacional de Energia Atomica, Universidad Nacional de Cuyo, 8400 Bariloche (Argentina); Dawidowski, J. [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Centro Atomico Bariloche, Instituto Balseiro, Comision Nacional de Energia Atomica, Universidad Nacional de Cuyo, 8400 Bariloche (Argentina)]. E-mail: javier@cab.cnea.gov.ar; Blostein, J.J. [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Centro Atomico Bariloche, Instituto Balseiro, Comision Nacional de Energia Atomica, Universidad Nacional de Cuyo, 8400 Bariloche (Argentina); Cuello, G.J. [Institut Laue Langevin, Boite Postale 156, F-38042 Grenoble Cedex 9 (France)

    2007-05-15

    We present a procedure to perform multiple scattering, attenuation and efficiency corrections in reactor neutron diffraction experiments, based on a Monte Carlo code applied iteratively. We discuss the application of two procedures, the first based on Granada's synthetic model, useful for incoherent scatterers, and the second, based on the measured experimental distributions for coherent scatterers. Experiments on samples of polyethylene, light water, heavy water and Teflon of different sizes were performed and the correction procedures are tested. The problem of normalization in an absolute scale in diffraction experiments is addressed and results obtained from the present procedure are shown.

  11. Gaussian mode selection with intracavity diffractive optics

    CSIR Research Space (South Africa)

    Litvin, IA

    2009-10-01

    Full Text Available in Optics Letters: Title:   Gaussian mode selection with intra–cavity diffractive optics Authors:   Andrew Forbes and Igor Litvin Accepted:   3 September 2009 Posted:   9 September 2009 Doc. ID:   113692 OSA Published by 1 Gaussian mode selection... with intra–cavity diffractive optics Igor A. Litvin1,2 and Andrew Forbes1,3 1CSIR National Laser Centre, PO Box 395, Pretoria 0001, South Africa 2Laser Research Institute, University of Stellenbosch, Stellenbosch 7602, South Africa 3School of Physics...

  12. Single Particle X-ray Diffractive Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bogan, M J; Benner, W H; Boutet, S; Rohner, U; Frank, M; Seibert, M; Maia, F; Barty, A; Bajt, S; Riot, V; Woods, B; Marchesini, S; Hau-Riege, S P; Svenda, M; Marklund, E; Spiller, E; Hajdu, J; Chapman, H N

    2007-10-01

    In nanotechnology, strategies for the creation and manipulation of nanoparticles in the gas phase are critically important for surface modification and substrate-free characterization. Recent coherent diffractive imaging with intense femtosecond X-ray pulses has verified the capability of single-shot imaging of nanoscale objects at sub-optical resolutions beyond the radiation-induced damage threshold. By intercepting electrospray-generated particles with a single 15 femtosecond soft-X-ray pulse, we demonstrate diffractive imaging of a nanoscale specimen in free flight for the first time, an important step toward imaging uncrystallized biomolecules.

  13. Film thickness determination by grazing incidence diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Battiston, G. A.; Gerbasi, R. [CNR, Padua (Italy). Istituto di Chimica e Tecnologie Inorganiche e dei Materiali Avanzati

    1996-09-01

    Thin films deposited via MOCVD (Metal Organic Chemical Vapour Deposition) are layers in the thickness range of a few manometers to about ten micrometers. An understanding of the physics and chemistry of films is necessary for a better comprehension of the phenomena involved in the film deposition procedure and its optimisation. Together with the crystalline phase a parameter that must be determined is the thickness of the layer. In this work the authors present a method for the measurement of the film thickness. This procedure, based on diffraction intensity absorption of the X-rays, both incident and diffracted in passing through the layers, resulted quite simple, rapid and non-destructive.

  14. Glancing angle synchrotron X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Cernik, R.J. [Daresbury Lab., Warrington, WA (United States)

    1996-09-01

    This paper describes in basic detail some of the techniques that can be used to study thin films and surfaces. These are all in the X-ray region and cover reflectivity, diffraction form polycrystalline films, textured films and single crystal films. Other effects such as fluorescence and diffuse scattering are mentioned but not discussed in detail. Two examples of the reflectivity from multilayers and the diffraction from iron oxide films are discussed. The advantages of the synchrotron for these studies is stressed and the experimental geometries that can be employed are described i detail. A brief bibliography is provided at the end to accompany this part of the 1996 Frascati school.

  15. Vector independent transmission of the vector-borne bluetongue virus.

    Science.gov (United States)

    van der Sluijs, Mirjam Tineke Willemijn; de Smit, Abraham J; Moormann, Rob J M

    2016-01-01

    Bluetongue is an economically important disease of ruminants. The causative agent, Bluetongue virus (BTV), is mainly transmitted by insect vectors. This review focuses on vector-free BTV transmission, and its epizootic and economic consequences. Vector-free transmission can either be vertical, from dam to fetus, or horizontal via direct contract. For several BTV-serotypes, vertical (transplacental) transmission has been described, resulting in severe congenital malformations. Transplacental transmission had been mainly associated with live vaccine strains. Yet, the European BTV-8 strain demonstrated a high incidence of transplacental transmission in natural circumstances. The relevance of transplacental transmission for the epizootiology is considered limited, especially in enzootic areas. However, transplacental transmission can have a substantial economic impact due to the loss of progeny. Inactivated vaccines have demonstrated to prevent transplacental transmission. Vector-free horizontal transmission has also been demonstrated. Since direct horizontal transmission requires close contact of animals, it is considered only relevant for within-farm spreading of BTV. The genetic determinants which enable vector-free transmission are present in virus strains circulating in the field. More research into the genetic changes which enable vector-free transmission is essential to better evaluate the risks associated with outbreaks of new BTV serotypes and to design more appropriate control measures.

  16. Image degradation characteristics and restoration based on regularization for diffractive imaging

    Science.gov (United States)

    Zhi, Xiyang; Jiang, Shikai; Zhang, Wei; Wang, Dawei; Li, Yun

    2017-11-01

    The diffractive membrane optical imaging system is an important development trend of ultra large aperture and lightweight space camera. However, related investigations on physics-based diffractive imaging degradation characteristics and corresponding image restoration methods are less studied. In this paper, the model of image quality degradation for the diffraction imaging system is first deduced mathematically based on diffraction theory and then the degradation characteristics are analyzed. On this basis, a novel regularization model of image restoration that contains multiple prior constraints is established. After that, the solving approach of the equation with the multi-norm coexistence and multi-regularization parameters (prior's parameters) is presented. Subsequently, the space-variant PSF image restoration method for large aperture diffractive imaging system is proposed combined with block idea of isoplanatic region. Experimentally, the proposed algorithm demonstrates its capacity to achieve multi-objective improvement including MTF enhancing, dispersion correcting, noise and artifact suppressing as well as image's detail preserving, and produce satisfactory visual quality. This can provide scientific basis for applications and possesses potential application prospects on future space applications of diffractive membrane imaging technology.

  17. Emergence of Fresnel diffraction zones in gravitational lensing by a cosmic string

    Energy Technology Data Exchange (ETDEWEB)

    Fernández-Núñez, Isabel [Departament de Física Quàntica i Astrofísica, Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain); Institut de Ciències del Cosmos (ICCUB), Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain); Bulashenko, Oleg, E-mail: oleg.bulashenko@ub.edu [Departament de Física Quàntica i Astrofísica, Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain)

    2017-06-09

    The possibility to detect cosmic strings – topological defects of early Universe, by means of wave effects in gravitational lensing is discussed. To find the optimal observation conditions, we define the hyperbolic-shaped Fresnel observation zones associated with the diffraction maxima and analyse the frequency patterns of wave amplification corresponding to different alignments. In particular, we show that diffraction of gravitational waves by the string may lead to significant amplification at cosmological distances. The wave properties we found are quite different from what one would expect, for instance, from light scattered off a thin wire or slit, since a cosmic string, as a topological defect, gives no shadow at all. - Highlights: • Interference and diffraction of gravitational waves by a cosmic string are studied. • Uniform asymptotic theory of diffraction is applied for a finite distance source. • Hyperbolic-shaped Fresnel observation zones associated with maxima of diffraction. • Frequency patterns modulated by diffraction for different string alignments are given. • The method is applicable to condensed-matter defects and other types of waves.

  18. Analysis of a non-diffractive beam generated from an annular beam in random media

    Science.gov (United States)

    Peng, Ziqi; Shiina, Tatsuo

    2017-11-01

    An annular beam has the ability to self-transform into a non-diffractive beam when it propagates in air at a long distance. In our previous study, we propagated an annular beam in random media and obtained a non-diffractive beam at a short propagation distance of a few tens centimeters by adjusting the concentration of random media and narrowing the view angle of the receiver. In this paper, we aim to analyze the components and characteristics of a non-diffractive beam and elucidate how the non-diffractive beam is generated in random media. The intensity variation of the scattered waveform is examined when the distance between the receiver and the back plane of a medium tank is changed. The waveform scattered in random media is constructed from forward scattering light at the center and multiple scattering light in the surrounding part. The forward scattering light at the center generates the non-diffractive beam. In numerical analysis based on diffusion theory, the calculation result of the non-diffractive beam shows agreement with the experimental result.

  19. Structure of TiO2 (011) revealed by photoelectron diffraction

    Science.gov (United States)

    Dupont, C.; Bourgeois, S.; Le Fèvre, P.; Verdini, A.; Floreano, L.; Domenichini, B.

    2016-12-01

    The combination of photoelectron diffraction, density functional theory, and multiple scattering calculations is used for a quantitative analysis of the widely debated structure of TiO2 (011). The modeling of the diffraction patterns for different surface reconstructions allows one to discriminate the key structural constraints required or, on the contrary, prohibited in the reconstruction of this termination. In particular, photodiffraction rules out previously proposed reconstructions while it evidences the key feature of the TiO2 (011) termination: an oxygen splitting induced by missing rows.

  20. Measurements of the Total, Elastic, Inelastic and Diffractive Cross Sections with the ATLAS Detector

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00237700; The ATLAS collaboration

    2016-01-01

    The main results of the total, elastic and inelastic cross sections measurements performed by the ATLAS ALFA detectors are presented. The independent inelastic cross section measurement done using Minimum Bias Trigger Scintillators is also shown. Next, the single diffractive di-jet production and gap survival probability are briefly described. After the event selection, it was found that the diffractive component is needed for a more complete description of data. Finally, the exclusive lepton pair production analysis in electron and muon channels is also described. The measured cross sections were found to be consistent with the theory prediction.

  1. Diffraction of short X-ray pulses in the general asymmetric Laue case - an analytic treatment.

    Science.gov (United States)

    Malgrange, C; Graeff, W

    2003-05-01

    After briefly describing the concept of short X-ray pulses (delta-function), the diffraction of such a short pulse by a crystal in the asymmetric Laue case is given. The results of the dynamical theory are adopted and an analytic result for the intensity distribution behind the crystal in the diffracted direction as well as in the forward direction is given and discussed in detail. The incoming delta pulse is no longer infinitely short but shows a pronounced structure over a limited temporal or spatial region which is connected to the well known Pendellösung effect. Also the limitations of these findings are critically inspected.

  2. Hard X-ray nanoimaging method using local diffraction from metal wire

    Energy Technology Data Exchange (ETDEWEB)

    Takano, Hidekazu, E-mail: htakano@sci.u-hyogo.ac.jp; Konishi, Shigeki; Shimomura, Sho; Azuma, Hiroaki; Tsusaka, Yoshiyuki; Kagoshima, Yasushi [Center for Novel Material Science under Multi-Extreme Conditions, Graduate School of Material Science, University of Hyogo, Kamigori, Hyogo 678-1297 (Japan)

    2014-01-13

    A simple hard X-ray imaging method achieving a high spatial resolution is proposed. Images are obtained by scanning a metal wire through the wave field to be measured and rotating the sample to collect data for back projection calculations; the local diffraction occurring at the edges of the metal wire operates as a narrow line probe. In-line holograms of a test sample were obtained with a spatial resolution of better than 100 nm. The potential high spatial resolution of this method is shown by calculations using diffraction theory.

  3. Introduction to matrices and vectors

    CERN Document Server

    Schwartz, Jacob T

    2001-01-01

    In this concise undergraduate text, the first three chapters present the basics of matrices - in later chapters the author shows how to use vectors and matrices to solve systems of linear equations. 1961 edition.

  4. All optical vector magnetometer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Phase I research project will investigate a novel method of operating an atomic magnetometer to simultaneously measure total magnetic fields and vector magnetic...

  5. GRE Enzymes for Vector Analysis

    Data.gov (United States)

    U.S. Environmental Protection Agency — Microbial enzyme data that were collected during the 2004-2006 EMAP-GRE program. These data were then used by Moorhead et al (2016) in their ecoenzyme vector...

  6. Quantum biological information theory

    CERN Document Server

    Djordjevic, Ivan B

    2016-01-01

    This book is a self-contained, tutorial-based introduction to quantum information theory and quantum biology. It serves as a single-source reference to the topic for researchers in bioengineering, communications engineering, electrical engineering, applied mathematics, biology, computer science, and physics. The book provides all the essential principles of the quantum biological information theory required to describe the quantum information transfer from DNA to proteins, the sources of genetic noise and genetic errors as well as their effects. Integrates quantum information and quantum biology concepts; Assumes only knowledge of basic concepts of vector algebra at undergraduate level; Provides a thorough introduction to basic concepts of quantum information processing, quantum information theory, and quantum biology; Includes in-depth discussion of the quantum biological channel modelling, quantum biological channel capacity calculation, quantum models of aging, quantum models of evolution, quantum models o...

  7. High-resolution diffraction grating interferometric transducer of linear displacements

    Science.gov (United States)

    Shang, Ping; Xia, Haojie; Fei, Yetai

    2016-01-01

    A high-resolution transducer of linear displacements is presented. The system is based on semiconductor laser illumination and a diffraction grating applied as a length master. The theory of the optical method is formulated using Doppler description. The relationship model among the interference strips, measurement errors, grating deflection around the X, Y and Z axes and translation along the Z axis is built. The grating interference strips' direction and space is not changed with movement along the X (direction of grating movement), Y (direction of grating line), Z axis, and the direction and space has a great effect when rotating around the X axis. Moreover the space is little affected by deflection around the Z axis however the direction is changed dramatically. In addition, the strips' position shifted rightward or downwards respectively for deflection around the X or Y axis. Because the emitted beams are separated on the grating plane, the tilt around the X axis error of the stage during motion will lead to the optical path difference of the two beams resulting in phase shift. This study investigates the influence of the tilt around the X axis error. Experiments show that after yaw error compensation, the high-resolution diffraction grating interferometric transducer readings can be significantly improved. The error can be reduced from +/-80 nm to +/-30 nm in maximum.

  8. A Note on Vector Bimeasures.

    Science.gov (United States)

    1987-11-01

    Phrases: N/A ] 19 RCT lontilue on revrm if necozsary and identify by block number) •"SA Fubini type theorem is obtained for vector bimasure integrals...Abstract A Fubini type theorem is obtained for vector bimeasure integrals. AMS (1980) subject classification: Primary 28B05; Secondary 60G12...Ylinen [11]. In the works mentioned above the authors consistently impose, in their definition of integrability. a Fubini type condition which cannot

  9. A uniform GTD analysis of the EM diffraction by a thin dielectric/ferrite half-plane and related configurations

    Science.gov (United States)

    Rojas, Roberto G.

    1985-01-01

    A uniform geometrical theory of diffraction (UTD) solution is developed for the problem of the diffraction by a thin dielectric/ferrite half plane when it is excited by a plane, cylindrical, or surface wave field. Both transverse electric and transverse magnetic cases are considered. The solution of this problem is synthesized from the solutions to the related problems of EM diffraction by configurations involving perfectly conducting electric and magnetic walls covered by a dielectric/ferrite half-plane of one half the thickness of the original half-plane.

  10. Neutron Powder Diffraction and Constrained Refinement

    DEFF Research Database (Denmark)

    Pawley, G. S.; Mackenzie, Gordon A.; Dietrich, O. W.

    1977-01-01

    The first use of a new program, EDINP, is reported. This program allows the constrained refinement of molecules in a crystal structure with neutron diffraction powder data. The structures of p-C6F4Br2 and p-C6F4I2 are determined by packing considerations and then refined with EDINP. Refinement...

  11. Nonlinearity management and diffraction management for the ...

    Indian Academy of Sciences (India)

    have shown that the diffraction management and nonlinearity management can sta- bilize the beam against decay or collapse providing undisturbed propagation even for larger energies of the incident beam. Acknowledgements. PAS would like to thank UGC, New Delhi for providing financial support for do- ing research ...

  12. Diffraction in ALICE and trigger efficiencies

    CERN Document Server

    Navin, Sparsh; Lietava, Roman

    ALICE is built to measure the properties of strongly interacting matter created in heavy-ion collisions. In addition, taking advantage of the low pT acceptance in the central barrel, ALICE is playing an important role in understanding pp collisions with minimum bias triggers at LHC energies. The work presented in this thesis is based on pp data simulated by the ALICE collaboration and early data collected at a center-of-mass energy of 7 TeV. A procedure to calculate trigger efficiencies and an estimate of the systematic uncertainty due to the limited acceptance of the detector are shown. A kinematic comparison between Monte Carlo event generators, PYTHIA 6, PYTHIA 8 and PHOJET is also presented. To improve the description of diffraction in PYTHIA, a hard diffractive component was added to PYTHIA 8 in 2009, which is described. Finally a trigger with a high efficiency for picking diffractive events is used to select a sample with an enhanced diffractive component from pp data. These data are compared to Monte ...

  13. Phase Transitions, Diffraction Studies and Marginal Dimensionality

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage

    1985-01-01

    Continuous phase transitions and the associated critical phenomena have been one of the most active areas of research in condensed matter physics for several decades. This short review is only one cut through this huge subject and the author has chosen to emphasize diffraction studies as a basic ...

  14. Neutron forward diffraction by single crystal prisms

    Indian Academy of Sciences (India)

    Abstract. We have derived analytic expressions for the deflection as well as transmitted fraction of monochromatic neutrons forward diffracted by a single crystal prism. In the vicinity of a Bragg reflection, the neutron deflection deviates sharply from that for an amorphous prism, exhibiting three orders of magnitude greater ...

  15. Non-Diffracting Waves: A new introduction

    CERN Document Server

    Recami, E; Hernandez-Figuera, H E; Ambrosio, L A

    2014-01-01

    This work deals with exact solutions to the wave equations. We start by introducing the Non-Diffracting Waves (NDW), and by a definition of NDWs. Afterwards we recall -besides ordinary waves (gaussian beams, gaussian pulses)- the simplest non diffracting waves (Bessel beams, X-shaped pulses,...). In Sec.2 we show how to eliminate any backward-traveling components, first in the case of ideal NDW pulses, and then, in Sec.3, for realistic finite-energy NDW pulses. In particular, in subsec.3.1 we forward a general functional expression for any totally-forward non-diffracting pulses. Then, in Sec.4 an efficient method is set forth for the analytic description of truncated beams, a byproduct of its being the elimination of any need of lengthy numerical calculations. In Sec.5 we explore the question of the subluminal NDWs, or bullets, in terms of two different methods, the second one allowing the analytic description of non-diffracting waves with a static envelope ("Frozen Waves", FW), in terms of continuous Bessel ...

  16. Diffractive Pedagogies: Dancing across New Materialist Imaginaries

    Science.gov (United States)

    Hickey-Moody, Anna; Palmer, Helen; Sayers, Esther

    2016-01-01

    We theorise an interdisciplinary arts practice university course and consider the forms of educational imaginary challenged by our curriculum. We argue for the disruptive and generative potential of what we call diffractive pedagogy as an example of the type of learning that can take place when materiality and entanglement are considered as vital…

  17. Multiple beam x-ray diffraction tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kewish, C.M.; Davis, J.R.; Coyle, R.A. [Monash University, Clayton, VIC (Australia). Department of Physics

    1999-12-01

    Full text: X-ray diffraction computed tomography (XDT) is an imaging modality that utilises scattered x-rays to reconstruct an image. Since its inception in 1985, various detection scenarios and imaging techniques have been developed to demonstrate the accuracy and applicability of XDT. Many of the previous methods for measuring the scattered x-rays from an object utilise detectors that accept x-rays scattered from the entire length of the raypath through the object. The detector apertures must therefore have dimensions similar to the largest width of the scanned object. This creates a situation where the detected x-rays are not derived from a single scattering angle. A new method of scanning the x-rays scattered from an object is presented which allows quantitative determination of the spatial distribution of differential scattering cross section within a cross-sectional plane of the object. The new method incorporates a position sensitive detector and an arrangement of Soller slits. The acquired data represents both spatial and angular information. For each raypath through the object, a partial diffraction projection is measured at the off-axis detector and a set of diffraction projections is assembled by combining the diffracted signal from all rays through the object. A reconstruction strategy that accounts for attenuation of the primary beam and the scattered beam allows us to reconstruct a map of the differential scattering cross section in the sample for a given angle. Copyright (1999) Australian X-ray Analytical Association Inc. 3 refs.

  18. Diffraction as a Consequence of Faraday's Law

    OpenAIRE

    Zolotorev, Max S.; McDonald, Kirk T.

    2000-01-01

    We consider a linearly polarized electromagnetic wave incident on an opaque screen with square aperture of edge a. An application of Faraday's law to a loop parallel to the screen, on the side away from the source, shows that the wave must have longitudinal components there. The ratio of the longitudinal to transverse field is a measure of the diffraction angle.

  19. Accessing the diffracted wavefield by coherent subtraction

    Science.gov (United States)

    Schwarz, Benjamin; Gajewski, Dirk

    2017-10-01

    Diffractions have unique properties which are still rarely exploited in common practice. Aside from containing subwavelength information on the scattering geometry or indicating small-scale structural complexity, they provide superior illumination compared to reflections. While diffraction occurs arguably on all scales and in most realistic media, the respective signatures typically have low amplitudes and are likely to be masked by more prominent wavefield components. It has been widely observed that automated stacking acts as a directional filter favouring the most coherent arrivals. In contrast to other works, which commonly aim at steering the summation operator towards fainter contributions, we utilize this directional selection to coherently approximate the most dominant arrivals and subtract them from the data. Supported by additional filter functions which can be derived from wave front attributes gained during the stacking procedure, this strategy allows for a fully data-driven recovery of faint diffractions and makes them accessible for further processing. A complex single-channel field data example recorded in the Aegean sea near Santorini illustrates that the diffracted background wavefield is surprisingly rich and despite the absence of a high channel count can still be detected and characterized, suggesting a variety of applications in industry and academia.

  20. Nonlinear diffraction of water waves by offshore stuctures

    Directory of Open Access Journals (Sweden)

    Matiur Rahman

    1986-01-01

    Full Text Available This paper is concerned with a variational formulation of a nonaxisymmetric water wave problem. The full set of equations of motion for the problem in cylindrical polar coordinates is derived. This is followed by a review of the current knowledge on analytical theories and numerical treatments of nonlinear diffraction of water waves by offshore cylindrical structures. A brief discussion is made on water waves incident on a circular harbor with a narrow gap. Special emphasis is given to the resonance phenomenon associated with this problem. A new theoretical analysis is also presented to estimate the wave forces on large conical structures. Second-order (nonlinear effects are included in the calculation of the wave forces on the conical structures. A list of important references is also given.

  1. Contemporary Use of Anomalous Diffraction in Biomolecular Structure Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Liu Q.; Hendrickson, W.

    2017-01-01

    The normal elastic X-ray scattering that depends only on electron density can be modulated by an ?anomalous? component due to resonance between X-rays and electronic orbitals. Anomalous scattering thereby precisely identifies atomic species, since orbitals distinguish atomic elements, which enables the multi- and single-wavelength anomalous diffraction (MAD and SAD) methods. SAD now predominates in de novo structure determination of biological macromolecules, and we focus here on the prevailing SAD method. We describe the anomalous phasing theory and the periodic table of phasing elements that are available for SAD experiments, differentiating between those readily accessible for at-resonance experiments and those that can be effective away from an edge. We describe procedures for present-day SAD phasing experiments and we discuss optimization of anomalous signals for challenging applications. We also describe methods for using anomalous signals as molecular markers for tracing and element identification. Emerging developments and perspectives are discussed in brief.

  2. Advanced Simulations of Optical Transition and Diffraction Radiation

    CERN Document Server

    AUTHOR|(CDS)2078350; Bobb, Lorraine Marie; Bolzon, B; Bravin, Enrico; Karataev, Pavel; Kruchinin, Konstantin; Lefevre, Thibaut; Mazzoni, Stefano

    2015-01-01

    Charged particle beam diagnostics is a key task in modern and future accelerator installations. The diagnostic tools are practically the “eyes” of the operators. The precision and resolution of the diagnostic equipment are crucial to define the performance of the accelerator. Transition and diffraction radiation (TR and DR) are widely used for electron beam parameter monitoring. However, the precision and resolution of those devices are determined by how well the production, transport and detection of these radiation types are understood. This paper reports on simulations of TR and DR spatial-spectral characteristics using the physical optics propagation (POP) mode of the Zemax advanced optics simulation software. A good consistency with theory is demonstrated. Also, realistic optical system alignment issues are discussed.

  3. Neutron Diffraction Study on the Magnetic Structure of Pr6Fe13Sn

    Directory of Open Access Journals (Sweden)

    Suharyana

    2010-04-01

    Full Text Available We have successfully prepared a Pr6Fe13Sn sample by employing argon arc melting. The crystal structure of the sample has been examined by an x-ray diffraction. The x-ray pattern reveals that the sample crystallize in the tetragonal Nd6Fe13Si structure type with space group I4/mcm. Neutron diffraction at 150K performed on a powder sample shows a collinear antiferromagnetic ordering of the Fe and Pr sublattices with the wave vector (0, 0, 1 and an Ip type magnetic lattice with anti-centering translation. The main axis of antiferromagnetism is restricted to the (0 0 1 plane. The average refined Fe moments at 150 K is (2.0±0.4 µB whereas the Pr moments are (2.1±0.4 and (1.9±0.4 µB for the 8f and 16l sites, respectively

  4. Theoretical and numerical investigations of sub-wavelength diffractive optical structures

    DEFF Research Database (Denmark)

    Dridi, Kim

    2000-01-01

    defect is described via the effective propagation puted for different crystal lattices and waveguide widths. Both strong positive, strong negative and zero disperions are possible. It is shown that geometric parameters such as the nature of the lattice, the line defect orientation, the defect width......The work in this thesis concerns theoretical and numerical investigations of sub-wavelength diffractive optical structures, relying on advanced two-dimensional vectorial numerical models that have applications in Optics and Electromagnetics. Integrated Optics is predicted to play a major role......, such as in dielectric waveguides with gratings and periodic media or photonic crystal structures. The vectorial electromagnetic nature of light is therefore taken into account in the modeling of these diffractive structures. An electromagnetic vector-field model for optical components design based on the classical...

  5. Electromagnetic design of an all-diffractive millimeter-wave imaging system.

    Science.gov (United States)

    Chen, Caihua; Shi, Shouyan; Prather, Dennis W

    2004-04-20

    We present the design and electromagnetic analysis of an all-diffractive millimeter-wave imaging system having a field of view of +/- 15 degrees. This system consists of two 16-level diffractive lenses, with the stop in contact with the first lens. By considering the Seidel aberrations for a diffractive lens and applying the corresponding stop shift formula, we established the expressions of third-order wave aberrations for this system. By setting all primary Seidel aberrations to zero and solving the corresponding system of equations, we obtained two sets of solutions for this two-element all-diffractive system, which totally compensate for all Seidel aberrations. To assess image system performance, we apply the finite-difference time-domain technique and a vector plane-wave spectrum method, in combination, to validate the performance of the system. To reduce the computational cost and thereby enable the complete electromagnetic analysis of the system, a four-step analysis procedure has been developed and applied as an electromagnetic system model.

  6. Study of Jet Structure in High Mass Diffraction at the SPS Collider

    CERN Multimedia

    2002-01-01

    The aim of the experiment is to study the class of events which have a quasi-elastic recoil proton or antiproton (with x^F~$>$~0.9) and also large transverse energy (hadronic and/or electromagnetic). The trigger is a minimum transverse energy in the UA2 calorimeter system and a diffractive recoil proton signature in a system of ``Mini-Drift'' wire chambers installed symmetrically in Roman-pots on both sides of LSS4. \\\\ \\\\ In single diffractive events of the type: .ce @*p @A @* + X + c.c. the system X is believed to result from a Pomeron-proton collision Pp~@A~X. We will study the energy flow in the UA2 detector and search for jet structure in high mass diffraction at @Rs~=~630~GeV in order to elucidate the nature of the Pomeron and its possible parton structure. Observation of electrons with high transverse momentum in coincidence with leading protons will signal the production of heavy flavour in high mass diffraction. Evidence for heavy vector boson production will be the signature for a q$\\bar{q}$ componen...

  7. Cosmological Solutions of Tensor–Vector Theories of Gravity by ...

    Indian Academy of Sciences (India)

    Also we set restrictions on the varying Einstein velocity to solve the horizon problem. This gives a selection rule for choosing the appropriate stable solution. We will see that it is possible to produce the background expansion history () indicated by observations. Finally we will discuss the behavior of the speed of light ...

  8. Coupled-wave analysis of vector holograms. 2. Reflective gratings formed in photoanisotropic medium with uniaxial birefringence.

    Science.gov (United States)

    Sasaki, Tomoyuki; Miura, Kenta; Hanaizumi, Osamu; Emoto, Akira; Ono, Hiroshi

    2011-02-01

    The diffraction properties of reflective anisotropic gratings, which can be recorded in photoanisotropic media with uniaxial birefringence by three-dimensional vector holography, were characterized through the use of coupled-wave analysis (CWA). By investigating the perturbation of the dielectric tensor, we demonstrated that the gratings with sinusoidal distribution of the azimuthal angle of the optic axis diffract polarized light in which the ordinary and extraordinary components are converted for incident light. The polarization conversion was consistent with that calculated by a numerical method. In addition, it was shown that CWA enables highly accurate calculation of the diffraction efficiency with wavelength dispersion when the amplitude of the azimuthal angle is small.

  9. Memory sparing, fast scattering formalism for rigorous diffraction modeling

    Science.gov (United States)

    Iff, W.; Kämpfe, T.; Jourlin, Y.; Tishchenko, A. V.

    2017-07-01

    The basics and algorithmic steps of a novel scattering formalism suited for memory sparing and fast electromagnetic calculations are presented. The formalism, called ‘S-vector algorithm’ (by analogy with the known scattering-matrix algorithm), allows the calculation of the collective scattering spectra of individual layered micro-structured scattering objects. A rigorous method of linear complexity is applied to model the scattering at individual layers; here the generalized source method (GSM) resorting to Fourier harmonics as basis functions is used as one possible method of linear complexity. The concatenation of the individual scattering events can be achieved sequentially or in parallel, both having pros and cons. The present development will largely concentrate on a consecutive approach based on the multiple reflection series. The latter will be reformulated into an implicit formalism which will be associated with an iterative solver, resulting in improved convergence. The examples will first refer to 1D grating diffraction for the sake of simplicity and intelligibility, with a final 2D application example.

  10. Analysis of dislocation loops by means of large-angle convergent beam electron diffraction

    CERN Document Server

    Jäger, C; Morniroli, J P; Jäger, W

    2002-01-01

    Diffusion-induced dislocation loops in GaP and GaAs were analysed by means of large-angle convergent beam electron diffraction (LACBED) and conventional contrast methods of transmission electron microscopy. It is demonstrated that LACBED is perfectly suited for use in analysing dislocation loops. The method combines analyses of the dislocation-induced splitting of Bragg lines in a LACBED pattern for the determination of the Burgers vector with analyses of the loop contrast behaviour in transmission electron microscopy bright-field images during tilt experiments, from which the habit plane of the dislocation loop is determined. Perfect dislocation loops formed by condensation of interstitial atoms or vacancies were found, depending on the diffusion conditions. The loops possess left brace 110 right brace-habit planes and Burgers vectors parallel to (110). The LACBED method findings are compared with results of contrast analyses based on the so-called 'inside-outside' contrast of dislocation loops. Advantages o...

  11. Spatial dispersion in two-dimensional plasmonic crystals: Large blueshifts promoted by diffraction anomalies

    DEFF Research Database (Denmark)

    David, Christin; Christensen, Johan; Mortensen, N. Asger

    2016-01-01

    We develop a methodology to incorporate nonlocal optical response of the free electron gas due to quantum-interaction effects in metal components of periodic two-dimensional plasmonic crystals and study the impact of spatial dispersion on promising building blocks for photonic circuits. Within th...... at normal incidence and the surprisingly large structural parameters at which finite blueshifts are observable, which we attribute to diffraction that offers nonvanishing in-plane wave vector components and increases the penetration depth of longitudinal (nonlocal) modes....

  12. International Conference Approximation Theory XIV

    CERN Document Server

    Schumaker, Larry

    2014-01-01

    This volume developed from papers presented at the international conference Approximation Theory XIV,  held April 7–10, 2013 in San Antonio, Texas. The proceedings contains surveys by invited speakers, covering topics such as splines on non-tensor-product meshes, Wachspress and mean value coordinates, curvelets and shearlets, barycentric interpolation, and polynomial approximation on spheres and balls. Other contributed papers address a variety of current topics in approximation theory, including eigenvalue sequences of positive integral operators, image registration, and support vector machines. This book will be of interest to mathematicians, engineers, and computer scientists working in approximation theory, computer-aided geometric design, numerical analysis, and related approximation areas.

  13. Hypergeometric series, modular linear differential equations, and vector-valued modular forms

    OpenAIRE

    Franc, Cameron; Mason, Geoffrey

    2015-01-01

    We survey the theory of vector-valued modular forms and their connections with modular differential equations and Fuchsian equations over the three-punctured sphere. We present a number of numerical examples showing how the theory in dimensions 2 and 3 leads naturally to close connections between modular forms and hypergeometric series.

  14. VectorBase: a home for invertebrate vectors of human pathogens

    Science.gov (United States)

    Lawson, Daniel; Arensburger, Peter; Atkinson, Peter; Besansky, Nora J.; Bruggner, Robert V.; Butler, Ryan; Campbell, Kathryn S.; Christophides, George K.; Christley, Scott; Dialynas, Emmanuel; Emmert, David; Hammond, Martin; Hill, Catherine A.; Kennedy, Ryan C.; Lobo, Neil F.; MacCallum, M. Robert; Madey, Greg; Megy, Karine; Redmond, Seth; Russo, Susan; Severson, David W.; Stinson, Eric O.; Topalis, Pantelis; Zdobnov, Evgeny M.; Birney, Ewan; Gelbart, William M.; Kafatos, Fotis C.; Louis, Christos; Collins, Frank H.

    2007-01-01

    VectorBase () is a web-accessible data repository for information about invertebrate vectors of human pathogens. VectorBase annotates and maintains vector genomes providing an integrated resource for the research community. Currently, VectorBase contains genome information for two organisms: Anopheles gambiae, a vector for the Plasmodium protozoan agent causing malaria, and Aedes aegypti, a vector for the flaviviral agents causing Yellow fever and Dengue fever. PMID:17145709

  15. Decays of the vector glueball

    Science.gov (United States)

    Giacosa, Francesco; Sammet, Julia; Janowski, Stanislaus

    2017-06-01

    We calculate two- and three-body decays of the (lightest) vector glueball into (pseudo)scalar, (axial-)vector, as well as pseudovector and excited vector mesons in the framework of a model of QCD. While absolute values of widths cannot be predicted because the corresponding coupling constants are unknown, some interesting branching ratios can be evaluated by setting the mass of the yet hypothetical vector glueball to 3.8 GeV as predicted by quenched lattice QCD. We find that the decay mode ω π π should be one of the largest (both through the decay chain O →b1π →ω π π and through the direct coupling O →ω π π ). Similarly, the (direct and indirect) decay into π K K*(892 ) is sizable. Moreover, the decays into ρ π and K*(892 )K are, although subleading, possible and could play a role in explaining the ρ π puzzle of the charmonium state ψ (2 S ) thanks to a (small) mixing with the vector glueball. The vector glueball can be directly formed at the ongoing BESIII experiment as well as at the future PANDA experiment at the FAIR facility. If the width is sufficiently small (≲100 MeV ) it should not escape future detection. It should be stressed that the employed model is based on some inputs and simplifying assumptions: the value of glueball mass (at present, the quenched lattice value is used), the lack of mixing of the glueball with other quarkonium states, and the use of few interaction terms. It then represents a first step toward the identification of the main decay channels of the vector glueball, but shall be improved when corresponding experimental candidates and/or new lattice results will be available.

  16. Finite-Size Scaling of Vector and Axial Current Correlators

    CERN Document Server

    Damgaard, P H; Jansen, K; Laine, Mikko; Lellouch, L P

    2003-01-01

    Using quenched chiral perturbation theory, we compute the long-distance behaviour of two-point functions of flavour non-singlet axial and vector currents in a finite volume, for small quark masses, and at a fixed gauge-field topology. We also present the corresponding predictions for the unquenched theory at fixed topology. These results can in principle be used to measure the low-energy constants of the chiral Lagrangian, from lattice simulations in volumes much smaller than one pion Compton wavelength. We show that quenching has a dramatic effect on the vector correlator, which is argued to vanish to all orders, while the axial correlator appears to be a robust observable only moderately sensitive to quenching.

  17. Zika Virus Mosquito Vectors: Competence, Biology, and Vector Control.

    Science.gov (United States)

    Kauffman, Elizabeth B; Kramer, Laura D

    2017-12-16

    Zika virus (ZIKV) (Flaviviridae, Flavivirus) has become one of the most medically important mosquito-borne viruses because of its ability to cause microcephaly in utero and Guillain-Barré syndrome in adults. This virus emerged from its sylvatic cycle in Africa to cause an outbreak in Yap, Federated States of Micronesia in 2007, French Polynesia in 2014, and most recently South America in 2015. The rapid expansion of ZIKV in the Americas largely has been due to the biology and behavior of its vector, Aedes aegypti. Other arboviruses transmitted by Ae. aegypti include the 2 flaviviruses dengue virus and yellow fever virus and the alphavirus chikungunya virus, which are also (re)emerging viruses in the Americas. This mosquito vector is highly domesticated, living in close association with humans in urban households. Its eggs are desiccation resistant, and the larvae develop rapidly in subtropical and tropical environments. Climate warming is facilitating range expansion of Ae. aegypti, adding to the threat this mosquito poses to human health, especially in light of the difficulty controlling it. Aedes albopictus, another highly invasive arbovirus vector that has only been implicated in one country (Gabon), is an important vector of ZIKV, but because of its wide geographic distribution may become a more important vector in the future. This article discusses the historical background of ZIKV and the biology and ecology of these 2 vectors. © The Author(s) 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

  18. Diffractive optical element with same diffraction pattern for multicolor light-emitting diodes.

    Science.gov (United States)

    Chen, Mengzhu; Wang, Qixia; Gu, Huarong; Tan, Qiaofeng

    2016-01-01

    The wavelength-division multiplexing technique can be utilized in visible light communication to increase the channel capacity when a multicolor mixed white LED is used as light source. In such an application, the illumination area of LEDs should be invariant to the incident wavelength, so as to decrease interference within the adjacent regions. Diffractive optical elements (DOEs) can be used in the optical transmitter system to shape the diffraction patterns into polygons. However, traditional DOEs illuminated by a multicolor mixed white LED would result into diffraction patterns with unequal sizes. In this paper, a hybrid algorithm which combines particle swarm optimization with a genetic algorithm is proposed for multicolor oriented DOEs design. A DOE is designed and fabricated for blue and red LEDs, and experimental results show that diffraction patterns with rather good uniformity as well as quasi-equal size for red and blue LEDs are obtained.

  19. Generalized Selection Weighted Vector Filters

    Directory of Open Access Journals (Sweden)

    Rastislav Lukac

    2004-09-01

    Full Text Available This paper introduces a class of nonlinear multichannel filters capable of removing impulsive noise in color images. The here-proposed generalized selection weighted vector filter class constitutes a powerful filtering framework for multichannel signal processing. Previously defined multichannel filters such as vector median filter, basic vector directional filter, directional-distance filter, weighted vector median filters, and weighted vector directional filters are treated from a global viewpoint using the proposed framework. Robust order-statistic concepts and increased degree of freedom in filter design make the proposed method attractive for a variety of applications. Introduced multichannel sigmoidal adaptation of the filter parameters and its modifications allow to accommodate the filter parameters to varying signal and noise statistics. Simulation studies reported in this paper indicate that the proposed filter class is computationally attractive, yields excellent performance, and is able to preserve fine details and color information while efficiently suppressing impulsive noise. This paper is an extended version of the paper by Lukac et al. presented at the 2003 IEEE-EURASIP Workshop on Nonlinear Signal and Image Processing (NSIP '03 in Grado, Italy.

  20. A generalized nonlocal vector calculus

    Science.gov (United States)

    Alali, Bacim; Liu, Kuo; Gunzburger, Max

    2015-10-01

    A nonlocal vector calculus was introduced in Du et al. (Math Model Meth Appl Sci 23:493-540, 2013) that has proved useful for the analysis of the peridynamics model of nonlocal mechanics and nonlocal diffusion models. A formulation is developed that provides a more general setting for the nonlocal vector calculus that is independent of particular nonlocal models. It is shown that general nonlocal calculus operators are integral operators with specific integral kernels. General nonlocal calculus properties are developed, including nonlocal integration by parts formula and Green's identities. The nonlocal vector calculus introduced in Du et al. (Math Model Meth Appl Sci 23:493-540, 2013) is shown to be recoverable from the general formulation as a special example. This special nonlocal vector calculus is used to reformulate the peridynamics equation of motion in terms of the nonlocal gradient operator and its adjoint. A new example of nonlocal vector calculus operators is introduced, which shows the potential use of the general formulation for general nonlocal models.

  1. Examination of Short- and Long-Range Atomic Order Nanocrystalline SiC and Diamond by Powder Diffraction Methods

    Science.gov (United States)

    Palosz, B.; Grzanka, E.; Stelmakh, S.; Gierlotka, S.; Weber, H.-P.; Proffen, T.; Palosz, W.

    2002-01-01

    The real atomic structure of nanocrystals determines unique, key properties of the materials. Determination of the structure presents a challenge due to inherent limitations of standard powder diffraction techniques when applied to nanocrystals. Alternate methodology of the structural analysis of nanocrystals (several nanometers in size) based on Bragg-like scattering and called the "apparent lattice parameter" (alp) is proposed. Application of the alp methodology to examination of the core-shell model of nanocrystals will be presented. The results of application of the alp method to structural analysis of several nanopowders were complemented by those obtained by determination of the Atomic Pair Distribution Function, PDF. Based on synchrotron and neutron diffraction data measured in a large diffraction vector of up to Q = 25 Angstroms(exp -1), the surface stresses in nanocrystalline diamond and SiC were evaluated.

  2. Performance evaluation of Bragg coherent diffraction imaging

    Science.gov (United States)

    Öztürk, H.; Huang, X.; Yan, H.; Robinson, I. K.; Noyan, I. C.; Chu, Y. S.

    2017-10-01

    In this study, we present a numerical framework for modeling three-dimensional (3D) diffraction data in Bragg coherent diffraction imaging (Bragg CDI) experiments and evaluating the quality of obtained 3D complex-valued real-space images recovered by reconstruction algorithms under controlled conditions. The approach is used to systematically explore the performance and the detection limit of this phase-retrieval-based microscopy tool. The numerical investigation suggests that the superb performance of Bragg CDI is achieved with an oversampling ratio above 30 and a detection dynamic range above 6 orders. The observed performance degradation subject to the data binning processes is also studied. This numerical tool can be used to optimize experimental parameters and has the potential to significantly improve the throughput of Bragg CDI method.

  3. Why is the diffraction peak a peak?

    CERN Document Server

    Cornille, H

    1975-01-01

    It is proved that the high-energy differential cross section for an elastic process has a maximum exactly in the forward direction and that the slope of the diffraction peak is at most (log s)/sup 2/. The widths of the diffraction peaks defined by the absorptive part and the differential cross section are compared. The assumptions are that the amplitude is dominated by the even signature amplitude and that the total cross section, if it decreases, decreases less fast than s/sup -1/2/. Strictly speaking, the results hold only for a sequence of energies approaching infinity. The proofs are given for the spin-O- spin-O case, but it is not unreasonable to hope that they can be generalized to arbitrary spins. (13 refs).

  4. Laser diffraction analysis of colloidal crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sogami, Ikuo S.; Shinohara, Tadatomi; Yoshiyama, Tsuyoshi [Kyoto Sangyo Univ., Department of Physics, Kyoto (Japan)

    2001-10-01

    Laser diffraction analysis is made on crystallization in salt-free aqueous suspensions of highly-charged colloidal particles for semi-dilute specimens of concentration 0.1-10.0 vol%. Kossel diffraction patterns which represent faithfully accurate information on lattice symmetries in the suspensions enable us to investigate the time evolution of colloidal crystals. The results show that the crystallization proceeds by way of the following intermediate phase transitions: two-dimensional hcp structure {yields} random layer structure {yields} layer structure with one sliding degree of freedom {yields} stacking disorder structure {yields} stacking structure with multivariant periodicity {yields} fcc twin structure with twin plane (111) {yields} normal fcc structure {yields} bcc twin structure with twin plane (11-bar2) or (1-bar12) {yields} normal bcc structure. For concentrated suspensions (>2 vol %), the phase transition ceases to proceed at the normal fcc structure. (author)

  5. X-ray diffraction with novel geometry

    Energy Technology Data Exchange (ETDEWEB)

    Prokopiou, Danae [Department of Engineering and Applied Science Cranfield University, Shrivenham Campus, Swindon (United Kingdom); Rogers, Keith, E-mail: k.d.rogers@cranfield.ac.uk [Department of Engineering and Applied Science Cranfield University, Shrivenham Campus, Swindon (United Kingdom); Evans, Paul; Godber, Simon [Imaging Science Group, School of Science and Technology, Nottingham Trent University Clifton Campus, Nottingham (United Kingdom); Shackel, James [Department of Engineering and Applied Science Cranfield University, Shrivenham Campus, Swindon (United Kingdom); Dicken, Anthony [Imaging Science Group, School of Science and Technology, Nottingham Trent University Clifton Campus, Nottingham (United Kingdom)

    2014-01-21

    An innovative geometry for high efficiency harvesting of diffracted X-rays is explored. Further to previous work where planar samples were fixed normal to the primary axis, this work extends focal construct geometry (FCG), to samples randomly oriented with respect to the incident beam. The effect of independent sample rotation around two axes upon the scattering distributions was investigated in analytical, simulation and empirical manners. It was found that, although the profile of Bragg maxima were modified when the sample was rotated, high intensity diffraction data was still acquired. Modelling produced a good match to the empirical data and it was shown that the distortions caused by sample rotation were not severe and predictable even when sample rotations were large. The implications for this are discussed.

  6. Diffractive and exclusive measurements at CDF

    Energy Technology Data Exchange (ETDEWEB)

    Gallinaro, Michele; /Rockefeller U.

    2006-06-01

    Experimental results from the CDF experiment at the Tevatron in p{bar p} collisions at {radical}s = 1.96 TeV are presented on the diffractive structure function at different values of the exchanged momentum transfer squared in the range 0 < Q{sup 2} < 10,000 GeV{sup 2}, on the four-momentum transfer |t| distribution in the region 0 < |t| < 1 GeV{sup 2} for both soft and hard diffractive events up to Q{sup 2} {approx} 4,500 GeV{sup 2}, and on the first experimental evidence of exclusive production in both dijet and diphoton events. A novel technique to align the Roman Pot detectors is also presented.

  7. ATLAS results on diffraction and exclusive production

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00224260; The ATLAS collaboration

    2017-01-01

    Various aspects of forward physics have been studied by the ATLAS collaboration using data from Run I at the LHC. In this text, main results of three published analyses are summarized, based on data from proton-proton collisions at $\\sqrt{s} = 7$ or 8 TeV collected between 2010 and 2012. One analysis deals with diffractive signature with at least two jets in the final state, the other two study exclusive production of a pair of leptons or W bosons.

  8. Geometrical camera calibration with diffractive optical elements.

    Science.gov (United States)

    Bauer, M; Griessbach, D; Hermerschmidt, A; Krüger, S; Scheele, M; Schischmanow, A

    2008-12-08

    Traditional methods for geometrical camera calibration are based on calibration grids or single pixel illumination by collimated light. A new method for geometrical sensor calibration by means of diffractive optical elements (DOE) in connection with a laser beam equipment is presented. This method can be especially used for 2D-sensor array systems but in principle also for line scanners. (c) 2008 Optical Society of America

  9. Basic of X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Giacovazzo, C. [Bari Univ. (Italy). Dip. Geomineralogico

    1996-09-01

    The basic concepts of X-ray diffraction may be more easily understood if it is made preliminary use of a mathematical background. In these pages the authors will first define the delta function and its use for the representation of a lattice. Then the concepts of Fourier transform and convolution are given. At the end of this talk one should realize that a crystal is the convolution of the lattice with a function representing the content of the unit cell.

  10. Non-diffractive beam in random media

    Science.gov (United States)

    Shiina, Tatsuo

    2017-09-01

    Beam propagation has been given important attention in a variety of applications in medicine, remote sensing and information science. Especially, the beam propagation in highly scattering media, which is called random media, is important. In general, the multiple scattering gets rid of beam characteristics, e.g., intensity distribution, phase front, and polarization. In this study, self-converging effect of annular beam was applied in random media. Diluted milk was used as random media, and the transmitted light was detected with a narrow view angle of 5.5mrad. The collimated annular beam of a few tens millimeters takes a few hundred meters to transform its beam shape into the non-diffractive beam in free space, while this transformation was shorten only to 20 cm in random media, that is, the collimated annular beam caused its transformation at only 20 cm in random media. The transformed beam kept its optical characteristics of ;non-diffractive beam;. Such transformation of the annular beam needs the appropriate condition of random media. Media concentration and propagation distance control the generation of the center peak intensity of the transformed beam. This study indicates the generation of the non-diffractive beam in random media and reveals its appropriate condition.

  11. Diffraction and rapidity gap measurements in ATLAS

    CERN Document Server

    Bernat, P; The ATLAS collaboration

    2012-01-01

    The early data recorded by the ATLAS detector during 2010 presents a great opportunity to study diffraction cross section in proton-proton collision. The differential cross section of diffractive dissociation is studied as a function of the maximum rapidity gap, up to 8 in rapidity units. Data are compared to different models of diffractive dynamics in standard event generators. A rise at large rapidity gaps is interpreted with a triple pomeron based approach, using Pythia 8 prediction (with a Donnachie-Landshoff model). A pomeron intercept of 1.058 ± 0.003(stat) +0.034-0.039 (syst) is found. A measurement of the dijet production with a jet veto on additional central activity using 2010 data is also presented. The use of a veto scale at 20 GeV allows to measure the jet activity in dijet events. As the veto scale is much larger than Lambda_s different QCD phenomena can be studied. Moreover, ATLAS data explores regions of the phase space for the first time. The main observable in this analysis is the fraction ...

  12. Suspended DNA structural characterization by TEM diffraction

    KAUST Repository

    Marini, Monica

    2017-12-01

    In this work, micro-fabrication, super-hydrophobic properties and a physiologically compatible preparation step are combined and tailored to obtain background free biological samples to be investigated by Transmission Electron Microscopy (TEM) diffraction technique. The validation was performed evaluating a well-known parameter such as the DNA interbases value. The diffraction spacing measured is in good agreement with those obtained by HRTEM direct metrology and by traditional X-Ray diffraction. This approach addresses single molecule studies in a simplified and reproducible straightforward way with respect to more conventional and widely used techniques. In addition, it overcomes the need of long and elaborated samples preparations: the sample is in its physiological environment and the HRTEM data acquisition occurs without any background interference, coating, staining or additional manipulation. The congruence in the results reported in this paper makes the application of this approach extremely promising towards those molecules for which crystallization remains a hurdle, such as cell membrane proteins and fibrillar proteins.

  13. Importance of Seismic Diffractions for Fractures Imaging

    Science.gov (United States)

    Bashir, Y.; Ghosh, D. P.; Moussavi Alashloo, S. Y.; Sum, C. W.

    2017-10-01

    The use of diffraction imaging is important and rapidly gaining momentum in the oil and gas industry as the need of the industry moves toward exploiting smaller and more complex structures to find hydrocarbon. Illumination of these small scale discrete transmissivity structures such as faults or fracture zones prior to exploration offers substantial benefits for all phases of field development. We have established a new way of seismic imaging through diffractions study using reflection seismology. A subsurface geological model is developed from one of highly productive field located in the southern part of the Malay Basin. To study the seismic component in reflection seismology, a Finite difference modelling is used to generate synthetic seismic data. Both velocity and density models are used for the explanation of wave propagation, intimating the subsurface from side to side in both one-way and two-wave wave propagation. One–way wave equation migration methods are tested to image the faults in the synthetic seismic section of the Malay basin and we demonstrated the need of diffraction imaging for highly dipping faults and complex structure.

  14. DNA hydration studied by neutron fiber diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, W.; Forsyth, V.T.; Mahendrasingam, A.; Langan, P.; Pigram, W.J. [Keele Univ. (United Kingdom)] [and others

    1994-12-31

    The development of neutron high angle fiber diffraction to investigate the location of water around the deoxyribonucleic acid (DNA) double-helix is described. The power of the technique is illustrated by its application to the D and A conformations of DNA using the single crystal diffractometer, D19, at the Institute Laue-Langevin, Grenoble and the time of flight diffractometer, SXD, at the Rutherford Appleton ISIS Spallation Neutron Source. These studies show the existence of bound water closely associated with the DNA. The patterns of hydration in these two DNA conformations are quite distinct and are compared to those observed in X-ray single crystal studies of two-stranded oligodeoxynucleotides. Information on the location of water around the DNA double-helix from the neutron fiber diffraction studies is combined with that on the location of alkali metal cations from complementary X-ray high angle fiber diffraction studies at the Daresbury Laboratory SRS using synchrotron radiation. These analyses emphasize the importance of viewing DNA, water and ions as a single system with specific interactions between the three components and provide a basis for understanding the effect of changes in the concentration of water and ions in inducing conformations] transitions in the DNA double-helix.

  15. Shock Wave Diffraction Phenomena around Slotted Splitters

    Directory of Open Access Journals (Sweden)

    Francesca Gnani

    2015-01-01

    Full Text Available In the field of aerospace engineering, the study of the characteristics of vortical flows and their unsteady phenomena finds numerous engineering applications related to improvements in the design of tip devices, enhancement of combustor performance, and control of noise generation. A large amount of work has been carried out in the analysis of the shock wave diffraction around conventional geometries such as sharp and rounded corners, but the employment of splitters with lateral variation has hardly attracted the attention of researchers. The investigation of this phenomenon around two-dimensional wedges has allowed the understanding of the basic physical principles of the flow features. On the other hand, important aspects that appear in the third dimension due to the turbulent nature of the vortices are omitted. The lack of studies that use three-dimensional geometries has motivated the current work to experimentally investigate the evolution of the shock wave diffraction around two splitters with spike-shaped structures for Mach numbers of 1.31 and 1.59. Schlieren photography was used to obtain an insight into the sequential diffraction processes that take place in different planes. Interacting among them, these phenomena generate a complicated turbulent cloud with a vortical arrangement.

  16. Synthetic Aperture Vector Flow Imaging

    DEFF Research Database (Denmark)

    Oddershede, Niels

    2008-01-01

    Current ultrasonic blood flow velocity measurement systems are subject to a number of limitations, including limited frame rate, aliasing artifacts, and that only the velocity component along the ultrasound beam is estimated. This dissertation aims at solving some of these problems. The main part...... of the thesis considers a method for estimating the two-dimensional velocity vector within the image plane. This method, called synthetic aperture vector flow imaging, is first shortly reviewed. The main contribution of this work is partly an analysis of the method with respect to focusing effects, motion...... estimation. The method can be used for increasing the frame rate of color flow maps or alternatively for a new imaging modality entitled quadroplex imaging, featuring a color flow map and two independent spectrograms at a high frame rate. The second is an alternative method for ultrasonic vector velocity...

  17. 3-D Vector Flow Imaging

    DEFF Research Database (Denmark)

    Holbek, Simon

    ultrasonic vector flow estimation and bring it a step closer to a clinical application. A method for high frame rate 3-D vector flow estimation in a plane using the transverse oscillation method combined with a 1024 channel 2-D matrix array is presented. The proposed method is validated both through phantom......For the last decade, the field of ultrasonic vector flow imaging has gotten an increasingly attention, as the technique offers a variety of new applications for screening and diagnostics of cardiovascular pathologies. The main purpose of this PhD project was therefore to advance the field of 3-D...... hampers the task of real-time processing. In a second study, some of the issue with the 2-D matrix array are solved by introducing a 2-D row-column (RC) addressing array with only 62 + 62 elements. It is investigated both through simulations and via experimental setups in various flow conditions...

  18. Toward lattice fractional vector calculus

    Science.gov (United States)

    Tarasov, Vasily E.

    2014-09-01

    An analog of fractional vector calculus for physical lattice models is suggested. We use an approach based on the models of three-dimensional lattices with long-range inter-particle interactions. The lattice analogs of fractional partial derivatives are represented by kernels of lattice long-range interactions, where the Fourier series transformations of these kernels have a power-law form with respect to wave vector components. In the continuum limit, these lattice partial derivatives give derivatives of non-integer order with respect to coordinates. In the three-dimensional description of the non-local continuum, the fractional differential operators have the form of fractional partial derivatives of the Riesz type. As examples of the applications of the suggested lattice fractional vector calculus, we give lattice models with long-range interactions for the fractional Maxwell equations of non-local continuous media and for the fractional generalization of the Mindlin and Aifantis continuum models of gradient elasticity.

  19. Study of QCD and Diffraction with the ATLAS detector at the LHC

    CERN Document Server

    Trzebinski, M; Royon, Christophe

    The thesis is devoted to the study of diffractive physics with the ATLAS detector at the LHC. After a short introduction to diffractive physics including soft and hard diffraction, the Jet-Gap-Jet production at the LHC, which is particularly interesting for testing the BFKL theory, is discussed. Using the signal selection cuts and a gap definition based on tracks reconstructed in the ATLAS Inner Detector, a clear signal of Jet-Gap-Jet events in the data was observed. Starting from the half-gap size of 0.8 the data cannot be properly described using only the Non-Diffractive Jet sample. Furthermore, the DPE JGJ production, with both protons tagged in the AFP stations, was demonstrated to provide a significant test of the BFKL theory, once the 300~pb$^{-1}$ of integrated luminosity is collected. In the last part of the thesis, the processes of Central Exclusive Jet and Exclusive $\\pi^+\\pi^-$ production was discussed. After the postulated data selection, the signal to background ratio was found to be of about 5/9...

  20. Matrix theory

    CERN Document Server

    Franklin, Joel N

    2003-01-01

    Mathematically rigorous introduction covers vector and matrix norms, the condition-number of a matrix, positive and irreducible matrices, much more. Only elementary algebra and calculus required. Includes problem-solving exercises. 1968 edition.

  1. Observation of parametric X-ray radiation in an anomalous diffraction region

    Energy Technology Data Exchange (ETDEWEB)

    Alexeyev, V.I., E-mail: vial@x4u.lebedev.ru [P.N. Lebedev Physical Institute RAS, 53 Leninskiy prospect, Moscow (Russian Federation); Belgorod National Research University, 85 Pobedy st., Belgorod (Russian Federation); Eliseyev, A.N., E-mail: elisseev@pluton.lpi.troitsk.ru [P.N. Lebedev Physical Institute RAS, 53 Leninskiy prospect, Moscow (Russian Federation); Belgorod National Research University, 85 Pobedy st., Belgorod (Russian Federation); Irribarra, E., E-mail: esteban.irribarra@epn.edu.ec [Escuela Politécnica Nacional, Ladrón de Guevara E11-253, Quito (Ecuador); Kishin, I.A., E-mail: ivan.kishin@mail.ru [P.N. Lebedev Physical Institute RAS, 53 Leninskiy prospect, Moscow (Russian Federation); Belgorod National Research University, 85 Pobedy st., Belgorod (Russian Federation); Kubankin, A.S., E-mail: kubankin@bsu.edu.ru [P.N. Lebedev Physical Institute RAS, 53 Leninskiy prospect, Moscow (Russian Federation); Belgorod National Research University, 85 Pobedy st., Belgorod (Russian Federation); Nazhmudinov, R.M., E-mail: fizeg@bk.ru [P.N. Lebedev Physical Institute RAS, 53 Leninskiy prospect, Moscow (Russian Federation); Belgorod National Research University, 85 Pobedy st., Belgorod (Russian Federation)

    2016-08-19

    A new possibility to expand the energy region of diffraction processes based on the interaction of relativistic charged particles with crystalline structures is presented. Diffracted photons related to parametric X-ray radiation produced by relativistic electrons are detected below the low energy threshold for the X-ray diffraction mechanism in crystalline structures for the first time. The measurements were performed during the interaction of 7 MeV electrons with a textured polycrystalline tungsten foil and a highly oriented pyrolytic graphite crystal. The experiment results are in good agreement with a developed model based on the PXR kinematical theory. The developed experimental approach can be applied to separate the contributions of real and virtual photons to the total diffracted radiation generated during the interaction of relativistic charged particles with crystalline targets. - Highlights: • Parametric X-ray radiation below the low energy threshold for diffraction of free X-rays. • Experimental separation of the contributions from different radiation mechanisms. • PXR from relativistic electrons in mosaic crystals and textured polycrystlas.

  2. Learning with Support Vector Machines

    CERN Document Server

    Campbell, Colin

    2010-01-01

    Support Vectors Machines have become a well established tool within machine learning. They work well in practice and have now been used across a wide range of applications from recognizing hand-written digits, to face identification, text categorisation, bioinformatics, and database marketing. In this book we give an introductory overview of this subject. We start with a simple Support Vector Machine for performing binary classification before considering multi-class classification and learning in the presence of noise. We show that this framework can be extended to many other scenarios such a

  3. VECTOR MAPS IN MOBILE ROBOTICS

    Directory of Open Access Journals (Sweden)

    Ales Jelinek

    2015-12-01

    Full Text Available The aim of this paper is to provide a brief overview of vector map techniques used in mobile robotics and to present current state of the research in this field at the Brno University of Technology. Vector maps are described as a part of the simultaneous localization and mapping (SLAM problem in the environment without artificial landmarks or global navigation system. The paper describes algorithms from data acquisition to map building but particular emphasis is put on segmentation, line extraction and scan matching algorithms. All significant algorithms are illustrated with experimental results.

  4. String Theory

    OpenAIRE

    Marino Beiras, Marcos

    2011-01-01

    We give an overview of the relations between matrix models and string theory, focusing on topological string theory and the Dijkgraaf--Vafa correspondence. We discuss applications of this correspondence and its generalizations to supersymmetric gauge theory, enumerative geometry and mirror symmetry. We also present a brief overview of matrix quantum mechanical models in superstring theory.

  5. Game Theory

    DEFF Research Database (Denmark)

    Game Theory is a collection of short interviews based on 5 questions presented to some of the most influential and prominent scholars in game theory. We hear their views on game theory, its aim, scope, use, the future direction of game theory and how their work fits in these respects....

  6. Ring Theory

    CERN Document Server

    Jara, Pascual; Torrecillas, Blas

    1988-01-01

    The papers in this proceedings volume are selected research papers in different areas of ring theory, including graded rings, differential operator rings, K-theory of noetherian rings, torsion theory, regular rings, cohomology of algebras, local cohomology of noncommutative rings. The book will be important for mathematicians active in research in ring theory.

  7. Modern Theory of Gratings Resonant Scattering: Analysis Techniques and Phenomena

    CERN Document Server

    Sirenko, Yuriy K

    2010-01-01

    Diffraction gratings are one of the most popular objects of analysis in electromagnetic theory. The requirements of applied optics and microwave engineering lead to many new problems and challenges for the theory of diffraction gratings, which force us to search for new methods and tools for their resolution. In Modern Theory of Gratings, the authors present results of the electromagnetic theory of diffraction gratings that will constitute the base of further development of this theory, which meet the challenges provided by modern requirements of fundamental and applied science. This volume covers: spectral theory of gratings (Chapter 1) giving reliable grounds for physical analysis of space-frequency and space-time transformations of the electromagnetic field in open periodic resonators and waveguides; authentic analytic regularization procedures (Chapter 2) that, in contradistinction to the traditional frequency-domain approaches, fit perfectly for the analysis of resonant wave scattering processes; paramet...

  8. An Overview of the Theory of Wire Media

    Science.gov (United States)

    2000-09-29

    determined by the effective media theory [5, 6]. We see from this figure that the normalized x-component of the wave vector in this sample wire medium is...band-gap phenomena, but instead it is due to the heavy inductive loading of the medium. Both effective- media theory and periodic-structure theory are

  9. How to Test String Theory: On Turing Machines / M-Theory Duality

    OpenAIRE

    coyle, dylan

    2017-01-01

    We introduce how Turing and vector machines are branes and strings, letting us use insight from game theory to test M-theory. We can test the antimater bias between converging systems, the cis-matter bias between diverging systems, a federated multiverse hypothesis, lower noise from heavy leptons, and the construction of 'black holes' with heavy leptonic atoms.

  10. Characterization and analysis of finite-beam Bragg diffraction in a periodically poled lithium niobate electro-optic grating.

    Science.gov (United States)

    Chang, J W; Yau, H F; Chung, H P; Chang, W K; Chen, Y H

    2014-08-20

    We report the study, both theoretical and experimental, of the finite-beam Bragg diffraction behavior of an electro-optic (EO) volume grating made of a periodically poled lithium niobate (PPLN) crystal. When a Gaussian laser beam is used, the experimental observations show that the diffraction characteristics of the PPLN EO Bragg device, including the diffraction mode pattern and diffraction efficiency, are closely related to the interaction beam size and applied voltage, which cannot be modeled properly by a simplified theory using the plane-wave approximation. In this work, we have developed a theoretical model for describing the diffraction behavior of a PPLN EO Bragg device based on the coupled-wave theory with the aid of the plane-wave decomposition method. Specifically, we found that it is the angular distribution (or the dephasing bandwidth) of the plane wave elements decomposed from the incident Gaussian beam and grating strength that determine the Bragg coupling behavior of the device. We also identified some other electro-optically induced effects in the PPLN grating as an important mechanism in affecting the diffraction performance of the present device, especially at high working voltages.

  11. SCALAR AND VECTOR IN COMPULATION

    Directory of Open Access Journals (Sweden)

    Valery F. Ochkov

    2013-01-01

    Full Text Available The article deals with two fundamental data types – scalar and vector (array, without the ability of working with them one cannot solve using computer school or university tasks in mathematics, physics, chemistry and other technical training courses. Some fundamentals of teaching computer science at school and university are covered as well. 

  12. Vector description of nonlinear magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Rysak, A. E-mail: rysak@tytan.umcs.lublin.pl; Korczak, S.Z

    2001-06-01

    The definition of the nonlinear magnetization, which is usually applied in investigating superconductors is discussed in this paper. The nonlinear magnetization of the superconductor, as the response to the alternating magnetic field, is a periodic time function and is determined by the sequence of complex numbers {chi}{sub n}={chi}{sub n}'+i{chi}{sub n}'', n=1,2,3,.... The sequence {chi}{sub n} is named harmonic susceptibility. Finding some limits in this definition we propose a new description, substituting the complex sequence {chi}{sub n} with the sequence of real covariant vectors. Such a definition of the nonlinear magnetization, allows to determine function M(t) of an investigated system for an arbitrary initial phase {theta}{sub o} of the inducing magnetic field H{sub ac}=h{sub ac} sin({omega}t+{theta}{sub o}). Vector description, in our opinion, is superior to the complex one in respect of explicitness, simplicity, and universality. Circular diagrams are used to illustrate the new vector description. We also show how the vectors of the harmonic susceptibility can be derived from both numeric calculations and experimental data.

  13. Disease Vector Ecology Profile: Ecuador

    Science.gov (United States)

    1998-12-01

    species) only during the pupal and adult stages. Formulations of Bacillus thuringiensis israelensis are economical, operationally feasible, and...12. Bees , Wasps and Hornets ..................................................................................31 B. Snakes...epidemic proportions. Transmission of the plague bacillus by fleas is species- specific. Not all fleas are competent vectors. Xenopsylla cheopis is the

  14. Parallel Sparse Matrix - Vector Product

    DEFF Research Database (Denmark)

    Alexandersen, Joe; Lazarov, Boyan Stefanov; Dammann, Bernd

    This technical report contains a case study of a sparse matrix-vector product routine, implemented for parallel execution on a compute cluster with both pure MPI and hybrid MPI-OpenMP solutions. C++ classes for sparse data types were developed and the report shows how these class can be used...

  15. Synthetic Aperture Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando

    The main objective of this project was to continue the development of a synthetic aperture vector flow estimator. This type of estimator is capable of overcoming two of the major limitations in conventional ultrasound systems: 1) the inability to scan large region of interest with high temporal r...

  16. The consequences of poor vectorization

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    This talk briefly discusses the vectorization problem and how it impacts scientific and engineering systems. A simple cost model of designing such system in context of different phases of software lifetime is considered. Finally a concept for scalable solution is presented.

  17. Constraints in vector meson photoproduction

    Energy Technology Data Exchange (ETDEWEB)

    Kloet, W. M.; Tabakin, F

    2000-01-31

    Constraints are discussed for spin observables extracted from photoproduction of vector mesons. These constraints originate from positivity of the spin density matrix and should be part of any future analysis of experimental data. Spin observables need to be defined in the photon-nucleon c.m. frame.

  18. Constraints in Vector Meson Photoproduction

    Science.gov (United States)

    Kloet, W. M.; Tabakin, F.

    2000-01-01

    Constraints are discussed for spin observables extracted from photoproduction of vector mesons. These constraints originate from positivity of the spin density matrix and should be part of any future analysis of experimental data. Spin observables need to be defined in the photon-nucleon c.m. frame.

  19. On Weighted Support Vector Regression

    DEFF Research Database (Denmark)

    Han, Xixuan; Clemmensen, Line Katrine Harder

    2014-01-01

    We propose a new type of weighted support vector regression (SVR), motivated by modeling local dependencies in time and space in prediction of house prices. The classic weights of the weighted SVR are added to the slack variables in the objective function (OF‐weights). This procedure directly...

  20. Portfolio Analysis for Vector Calculus

    Science.gov (United States)

    Kaplan, Samuel R.

    2015-01-01

    Classic stock portfolio analysis provides an applied context for Lagrange multipliers that undergraduate students appreciate. Although modern methods of portfolio analysis are beyond the scope of vector calculus, classic methods reinforce the utility of this material. This paper discusses how to introduce classic stock portfolio analysis in a…