Sample records for symmetric top molecules

  1. Inertial defects of planar symmetric top molecules

    Microsoft Academic Search

    Mary-Frances Jagod; Takeshi Oka

    1990-01-01

    A general expression for the inertial defects of planar symmetric top molecules has been derived and applied to H3+, CH3+, C3H3+, and C6H6-type molecules. It has been found that the inertial derivatives analphaalpha for these molecules can be expressed in terms of Coriolis constants. This allowed us to find a sufficient number of relations among Coriolis constants that the number

  2. Realizing unconventional quantum magnetism with symmetric top molecules

    NASA Astrophysics Data System (ADS)

    Wall, M. L.; Maeda, K.; Carr, Lincoln D.

    2015-02-01

    We demonstrate that ultracold symmetric top molecules loaded into an optical lattice can realize highly tunable and unconventional models of quantum magnetism, such as an XYZ Heisenberg spin model. We show that anisotropic dipole–dipole interactions between molecules can lead to effective spin–spin interactions which exchange spin and orbital angular momentum. This exchange produces effective spin models which do not conserve magnetization and feature tunable degrees of spatial and spin–coupling anisotropy. In addition to deriving pure spin models when molecules are pinned in a deep optical lattice, we show that models of itinerant magnetism are possible when molecules can tunnel through the lattice. Additionally, we demonstrate rich tunability of effective model parameters using only a single microwave frequency, in contrast to proposals with 1? diatomic molecules, which often require many microwave frequencies. Our results are germane not only for experiments with polyatomic symmetric top molecules, such as methyl fluoride (CH3F), but also diatomic molecules with an effective symmetric top structure, such as the hydroxyl radical OH.

  3. Critical binding and electron scattering by symmetric-top polar molecules

    SciTech Connect

    Garrett, W. R., E-mail: wrg@utk.edu [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States)

    2014-10-28

    Quantum treatments of electron interactions with polar symmetric-top rotor molecules show features not present in the treatment of the linear-polar-rotor model. For symmetric tops possessing non-zero angular momentum about the symmetry axis, a new critical dipole can be defined that guarantees an infinite set of dipole-bound states independent of the values of the components of the inertial tensor. Additionally, for this same class, the scattering cross section diverges for all nonzero values of dipole moments and inertial moments, similar to solutions for the fixed linear dipole. Additional predictions are presented for electron affinities and rotational resonances of these systems.

  4. Theory of x-ray absorption by laser-aligned symmetric-top molecules.

    SciTech Connect

    Buth, C.; Santra, R.; Chemical Sciences and Engineering Division

    2008-01-01

    We devise a theory of x-ray absorption by symmetric-top molecules which are aligned by an intense optical laser. Initially, the density matrix of the system is composed of the electronic ground state of the molecules and a thermal ensemble of rigid-rotor eigenstates. We formulate equations of motion of the two-color (laser plus x rays) rotational-electronic problem. The interaction with the laser is assumed to be nonresonant; it is described by an electric dipole polarizability tensor. X-ray absorption is approximated as a one-photon process. It is shown that the equations can be separated such that the interaction with the laser can be treated independently of the x rays. The laser-only density matrix is propagated numerically. After each time step, the x-ray absorption is calculated. We apply our theory to study adiabatic alignment of bromine molecules (Br2). The required dynamic polarizabilities are determined using the ab initio linear response methods coupled-cluster singles (CCS), second-order approximate coupled-cluster singles and doubles (CC2), and coupled-cluster singles and doubles (CCSD). For the description of x-ray absorption on the {sigma}g1s-->{sigma}u4p resonance, a parameter-free two-level model is used for the electronic structure of the molecules. Our theory opens up novel perspectives for the quantum control of x-ray radiation.

  5. Rovibrational Interaction and Vibrational Constants of the Symmetric Top Molecule 14NF3

    PubMed Central

    2013-01-01

    Several accurate experimental values of the ?C and ?B rotation-vibration interaction parameters and ?i, xij, and gij vibrational constants have been extracted from the most recent high-resolution Fourier transform infrared, millimeter wave, and centimeter wave investigations in the spectra of the oblate symmetric top molecule 14NF3. The band-centres used are those of the four fundamental, the overtones, the combination, and hot bands identified in the region between 400?cm?1 and 2000?cm?1. Comparison of our constants with the ones measured previously, by infrared spectroscopy at low resolution, reveals orders of magnitude higher accuracy of the new values. The agreement between our values and those determined by ab initio calculations employing the TZ2Pf basis is excellent. PMID:23766711

  6. Unveiling the nonadiabatic rotational excitation process in a symmetric-top molecule induced by two intense laser pulses.

    PubMed

    Baek, Daeyul; Hasegawa, Hirokazu; Ohshima, Yasuhiro

    2011-06-14

    We experimentally investigate the nonadiabatic rotational excitation process of a symmetric-top molecule, benzene, in the electronic ground state irradiated by intense nonresonant ultrafast laser fields. The initial rotational-state distribution was restricted mostly to the five lowest levels with different nuclear spin modifications by an extensive adiabatic cooling with the rotational temperature well below 1 K, and distributions after the interaction with a femtosecond double-pulse pair (3-5 TW/cm(2) each with 160 fs duration) with time delays were probed in a quantum-state resolved manner by employing resonant enhanced multiphoton ionization via the S(1) ? S(0) 6(0) (1) vibronic transition. Populations of 10 rotational levels with J ranging from 0 to 4 and K from 0 to 3 were examined to show an oscillatory dependence on the time delay between the two pulses. Fourier analysis of the beat signals provides the coupling strengths between the constituent levels of the rotational wave packets created by the nonadiabatic excitation. These data are in good agreement with the results from quantum mechanical calculations, evidencing stepwise excitation pathways in the wave packet creation with ?J = 2 in the K = 0 stack while ?J = 1 and 2 in the K > 0 stacks. PMID:21682509

  7. Quantum effects in the capture of charged particles by dipolar polarizable symmetric top molecules. II. Interplay between electrostatic and gyroscopic interactions.

    PubMed

    Auzinsh, M; Dashevskaya, E I; Litvin, I; Nikitin, E E; Troe, J

    2013-10-14

    Within the general axially nonadiabatic channel approach described in Paper I of this series [M. Auzinsh, E. I. Dashevskaya, I. Litvin, E. E. Nikitin, and J. Troe, J. Chem. Phys. 139, 084311 (2013)], the present article analyzes the simultaneous manifestation of electrostatic and gyroscopic interactions in the quantum capture of dipolar polarizable symmetric top molecules by ions. As a demonstration, the rate coefficients for capture of CH3D and CD3H by H(+), D(+), and H3(+) are calculated. PMID:24116627

  8. Rotational Spectra of Symmetric Top Molecules in Ground and Different Vibrational Excited States, and Phenomenon of Resonance – Applying in CF3CCH

    PubMed Central

    Motamedi, Masoud

    2007-01-01

    This paper deals with review of exploration of resonance in symmetric top molecules in different vibrational excited states, vt = n (n =1, 2, 3, 4). Calculations for CF3CCH shows that resonance take place at k=x??+(A-B)-2A?A?-(A-B) and k=x??+(A-B)-2A?A?-(A-B) for v10 = 2 and v10 = 3 respectively. In order to account for splitting about 3 MHz for the ? 2 series in v10 = 4 is necessary to introduce the element ? J,k, ?|f24| J,k + 2, ? ? 4? in fitting program.

  9. Collision dynamics of symmetric top molecules: a comparison of the rotationally inelastic scattering of CD3 and ND3 with He.

    PubMed

    Tká?, Ond?ej; Orr-Ewing, Andrew J; Dagdigian, Paul J; Alexander, Millard H; Onvlee, Jolijn; van der Avoird, Ad

    2014-04-01

    We compare rotationally inelastic scattering of deuterated methyl radicals (CD3) and ammonia (ND3) in collisions with helium using close-coupling quantum-mechanical scattering calculations performed with ab initio potential energy surfaces (PESs). The theoretical methods have been rigorously tested against angle-resolved experimental measurements obtained using crossed molecular beam apparatuses in combination with velocity map imaging [O. Tká?, A. G. Sage, S. J. Greaves, A. J. Orr-Ewing, P. J. Dagdigian, Q. Ma, and M. H. Alexander, Chem. Sci. 4, 4199 (2013); O. Tká?, A. K. Saha, J. Onvlee, C.-H. Yang, G. Sarma, C. K. Bishwakarma, S. Y. T. van de Meerakker, A. van der Avoird, D. H. Parker, and A. J. Orr-Ewing, Phys. Chem. Chem. Phys. 16, 477 (2014)]. Common features of the scattering dynamics of these two symmetric top molecules, one closed-shell and the other an open-shell radical, are identified and discussed. Two types of anisotropies in the PES influence the interaction of an atom with a nonlinear polyatomic molecule. The effects of these anisotropies can be clearly seen in the state-to-state integral cross sections out of the lowest CD3 rotational levels of each nuclear spin symmetry at a collision energy of 440 cm(-1). Similarities and differences in the differential cross sections for the ND3-He and CD3-He systems can be linked to the coupling terms derived from the PESs which govern particular initial to final rotational level transitions. PMID:24712794

  10. Collision dynamics of symmetric top molecules: A comparison of the rotationally inelastic scattering of CD3 and ND3 with He

    NASA Astrophysics Data System (ADS)

    Tká?, Ond?ej; Orr-Ewing, Andrew J.; Dagdigian, Paul J.; Alexander, Millard H.; Onvlee, Jolijn; van der Avoird, Ad

    2014-04-01

    We compare rotationally inelastic scattering of deuterated methyl radicals (CD3) and ammonia (ND3) in collisions with helium using close-coupling quantum-mechanical scattering calculations performed with ab initio potential energy surfaces (PESs). The theoretical methods have been rigorously tested against angle-resolved experimental measurements obtained using crossed molecular beam apparatuses in combination with velocity map imaging [O. Tká?, A. G. Sage, S. J. Greaves, A. J. Orr-Ewing, P. J. Dagdigian, Q. Ma, and M. H. Alexander, Chem. Sci. 4, 4199 (2013); O. Tká?, A. K. Saha, J. Onvlee, C.-H. Yang, G. Sarma, C. K. Bishwakarma, S. Y. T. van de Meerakker, A. van der Avoird, D. H. Parker, and A. J. Orr-Ewing, Phys. Chem. Chem. Phys. 16, 477 (2014)]. Common features of the scattering dynamics of these two symmetric top molecules, one closed-shell and the other an open-shell radical, are identified and discussed. Two types of anisotropies in the PES influence the interaction of an atom with a nonlinear polyatomic molecule. The effects of these anisotropies can be clearly seen in the state-to-state integral cross sections out of the lowest CD3 rotational levels of each nuclear spin symmetry at a collision energy of 440 cm-1. Similarities and differences in the differential cross sections for the ND3-He and CD3-He systems can be linked to the coupling terms derived from the PESs which govern particular initial to final rotational level transitions.

  11. Collision dynamics of symmetric top molecules: A comparison of the rotationally inelastic scattering of CD{sub 3} and ND{sub 3} with He

    SciTech Connect

    Tká?, Ond?ej; Orr-Ewing, Andrew J. [School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS (United Kingdom)] [School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS (United Kingdom); Dagdigian, Paul J., E-mail: pjdagdigian@jhu.edu [Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218-2685 (United States); Alexander, Millard H. [Department of Chemistry and Biochemistry and Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742-2021 (United States)] [Department of Chemistry and Biochemistry and Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742-2021 (United States); Onvlee, Jolijn; Avoird, Ad van der, E-mail: avda@theochem.ru.nl [Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525AJ Nijmegen (Netherlands)

    2014-04-07

    We compare rotationally inelastic scattering of deuterated methyl radicals (CD{sub 3}) and ammonia (ND{sub 3}) in collisions with helium using close-coupling quantum-mechanical scattering calculations performed with ab initio potential energy surfaces (PESs). The theoretical methods have been rigorously tested against angle-resolved experimental measurements obtained using crossed molecular beam apparatuses in combination with velocity map imaging [O. Tká?, A. G. Sage, S. J. Greaves, A. J. Orr-Ewing, P. J. Dagdigian, Q. Ma, and M. H. Alexander, Chem. Sci. 4, 4199 (2013); O. Tká?, A. K. Saha, J. Onvlee, C.-H. Yang, G. Sarma, C. K. Bishwakarma, S. Y. T. van de Meerakker, A. van der Avoird, D. H. Parker, and A. J. Orr-Ewing, Phys. Chem. Chem. Phys. 16, 477 (2014)]. Common features of the scattering dynamics of these two symmetric top molecules, one closed-shell and the other an open-shell radical, are identified and discussed. Two types of anisotropies in the PES influence the interaction of an atom with a nonlinear polyatomic molecule. The effects of these anisotropies can be clearly seen in the state-to-state integral cross sections out of the lowest CD{sub 3} rotational levels of each nuclear spin symmetry at a collision energy of 440 cm{sup ?1}. Similarities and differences in the differential cross sections for the ND{sub 3}–He and CD{sub 3}–He systems can be linked to the coupling terms derived from the PESs which govern particular initial to final rotational level transitions.

  12. Horseshoes for the nearly symmetric heavy top

    NASA Astrophysics Data System (ADS)

    van der Heijden, G. H. M.; Yagasaki, Kazuyuki

    2014-04-01

    We prove the existence of horseshoes in the nearly symmetric heavy top. This problem was previously addressed but treated inappropriately due to a singularity of the equations of motion. We introduce an (artificial) inclined plane to remove this singularity and use a Melnikov-type approach to show that there exist transverse homoclinic orbits to periodic orbits on four-dimensional level sets. The price we pay for removing the singularity is that the Hamiltonian system becomes a three-degree-of-freedom system with an additional first integral, unlike the two-degree-of-freedom formulation in the classical treatment. We therefore have to analyze three-dimensional stable and unstable manifolds of periodic orbits in a six-dimensional phase space. A new Melnikov-type technique is developed for this situation. Numerical evidence for the existence of transverse homoclinic orbits on a four-dimensional level set is also given.

  13. Symmetric protein architecture in protein design: top-down symmetric deconstruction.

    PubMed

    Longo, Liam M; Blaber, Michael

    2014-01-01

    Top-down symmetric deconstruction (TDSD) is a joint experimental and computational approach to generate a highly stable, functionally benign protein scaffold for intended application in subsequent functional design studies. By focusing on symmetric protein folds, TDSD can leverage the dramatic reduction in sequence space achieved by applying a primary structure symmetric constraint to the design process. Fundamentally, TDSD is an iterative symmetrization process, in which the goal is to maintain or improve properties of thermodynamic stability and folding cooperativity inherent to a starting sequence (the "proxy"). As such, TDSD does not attempt to solve the inverse protein folding problem directly, which is computationally intractable. The present chapter will take the reader through all of the primary steps of TDSD-selecting a proxy, identifying potential mutations, establishing a stability/folding cooperativity screen-relying heavily on a successful TDSD solution for the common ?-trefoil fold. PMID:25213415

  14. CMISTARK: Python package for the Stark-effect calculation and symmetry classification of linear, symmetric and asymmetric top wavefunctions in dc electric fields

    NASA Astrophysics Data System (ADS)

    Chang, Yuan-Pin; Filsinger, Frank; Sartakov, Boris G.; Küpper, Jochen

    2014-01-01

    The Controlled Molecule Imaging group (CMI) at the Center for Free Electron Laser Science (CFEL) has developed the CMISTARK software to calculate, view, and analyze the energy levels of adiabatic Stark energy curves of linear, symmetric top and asymmetric top molecules. The program exploits the symmetry of the Hamiltonian to generate fully labeled adiabatic Stark energy curves.

  15. Hamiltonian dynamics of a symmetric top in external fields having axial symmetry. Levitating Orbitron

    E-print Network

    Stanislav S. Zub; Sergiy I. Zub

    2015-02-13

    The symmetric top is a special case of the general top, and canonical Poisson structure on $T^*SE(3)$ is the common method of its description. This structure is invariant under the right action of $SO(3)$, but the Hamiltonian of the symmetric top is invariant only under the right action of subgroup $S^1$ that corresponds to the rotation around the symmetry axis of the symmetric top. So, its Poisson structure was obtained as the reduction $T^*SE(3)/S^1$. Next we propose the Hamiltonian that describes the wide class of the interaction models of symmetric top and axially-symmetric external field. The stability of the levitating Orbitron in relative equilibrium was proved.

  16. Alignment of asymmetric-top molecules using multiple-pulse trains

    NASA Astrophysics Data System (ADS)

    Pabst, Stefan; Santra, Robin

    2010-06-01

    We theoretically analyze the effectiveness of multiple-pulse laser alignment methods for asymmetric-top molecules. As an example, we choose SO2 and investigate the alignment dynamics induced by two different sequences, each consisting of four identical laser pulses. Each sequence differs only in the time delay between the pulses. Equally spaced pulses matching the alignment revival of the symmetrized SO2 rotor model are exploited in the first sequence. The pulse separations in the second sequence are short compared to the rotation dynamics of the molecule and monotonically increase the degree of alignment until the maximum alignment is reached. We point out the significant differences between the alignment dynamics of SO2 treated as an asymmetric-top and a symmetric-top rotor, respectively. We also explain why the fast sequence of laser pulses creates considerably stronger one-dimensional molecular alignment for asymmetric-top molecules. In addition, we show that multiple-pulse trains with elliptically polarized pulses do not enhance one-dimensional alignment or create three-dimensional alignment.

  17. A polypeptide "building block" for the ?-trefoil fold identified by "top-down symmetric deconstruction".

    PubMed

    Lee, Jihun; Blaber, Sachiko I; Dubey, Vikash K; Blaber, Michael

    2011-04-15

    Fibroblast growth factor-1, a member of the 3-fold symmetric ?-trefoil fold, was subjected to a series of symmetric constraint mutations in a process termed "top-down symmetric deconstruction." The mutations enforced a cumulative exact 3-fold symmetry upon symmetrically equivalent positions within the protein and were combined with a stability screen. This process culminated in a ?-trefoil protein with exact 3-fold primary-structure symmetry that exhibited excellent folding and stability properties. Subsequent fragmentation of the repeating primary-structure motif yielded a 42-residue polypeptide capable of spontaneous assembly as a homotrimer, producing a thermostable ?-trefoil architecture. The results show that despite pronounced reduction in sequence complexity, pure symmetry in the design of a foldable, thermostable ?-trefoil fold is possible. The top-down symmetric deconstruction approach provides a novel alternative means to successfully identify a useful polypeptide "building block" for subsequent "bottom-up" de novo design of target protein architecture. PMID:21315087

  18. Molecular collisions. 11: Semiclassical approximation to atom-symmetric top rotational excitation

    NASA Technical Reports Server (NTRS)

    Russell, D.; Curtiss, C. F.

    1973-01-01

    In a paper of this series a distorted wave approximation to the T matrix for atom-symmetric top scattering was developed which is correct to first order in the part of the interaction potential responsible for transitions in the component of rotational angular momentum along the symmetry axis of the top. A semiclassical expression for this T matrix is derived by assuming large values of orbital and rotational angular momentum quantum numbers.

  19. Molecular collisions 21: Semiclassical approximation to atom-symmetric top rotational excitation

    NASA Technical Reports Server (NTRS)

    Russell, D.; Curtiss, C. F.

    1973-01-01

    A distorted wave approximation to the T matrix for atom-symmetric top scattering was developed. The approximation is correct to first order in the part of the interaction potential responsible for transitions in the component of rotational angular momentum along the symmetry axis of the top. A semiclassical expression for this T matrix is derived by assuming large values of orbital and rotational angular momentum quantum numbers.

  20. Building 2D crystals from 5-fold-symmetric molecules.

    PubMed

    Bauert, Tobias; Merz, Leo; Bandera, Davide; Parschau, Manfred; Siegel, Jay S; Ernst, Karl-Heinz

    2009-03-18

    Concepts of close packing in monolayers of 5-fold-symmetric buckybowls are discussed. When the symmetry of lattice and molecular building blocks are incompatible, new strategies evolve. Corannulene forms a hexagonal lattice on Cu(111) by tilting away from the C(5) symmetry and aligning one hexagonal ring parallel to the surface. The chiral 5-fold-substituted chloro and methyl derivatives do not show this tilt and maintain the 5-fold symmetry as adsorbates. Consequently, a nonperfect tiling is observed. Their lattices are quasi-hexagonal: one in an antiparallel fashion with almost pm symmetry and the other with azimuthal and positional disorder on the hexagonal grid. Our results are in remarkable agreement with computational and mechanical modeling experiments of close packing of hard pentagonal discs in macroscopic two-dimensional systems and prove the validity of such modeling strategies. PMID:19236092

  1. Perturbations of the dominant approximation in spherical-top molecules

    NASA Astrophysics Data System (ADS)

    Krohn, Burton J.; Watson, James K. G.

    1988-06-01

    The tensor perturbations in the rotational fine structure of spherical-top fundamental vibrational bands are analyzed in detail. The shift of a fine-structure sublevel ( v = 1, J, R, p) is the result of fourth-rank tensor interactions with sublevels belonging to other manifolds with the same J but different R', due to the matrix elements < v = 1, J, R, p| H| v = 1, J, R', p'>, which are proportional to the symmetry-adapted vector-coupling coefficients FA1 pp' (4, R, R') of Moret-Bailly. Sum rules are derived for general binary products of these matrix elements, and for particular linear combinations of ternary and binary products arising in perturbation theory. These lead to analytical expressions for the second- and third-order perturbation corrections to the transition wavenumbers. To this order of approximation the formulas are expressed in terms of scalar functions of J and R, diagonalF(4) and F(6) tensor functions, and the g˜ function of Ozier. For the third-order formulas, many tedious algebraic manipulations were avoided by computing the sums numerically for each value of ( R - J) and a range of values of R, and then obtaining the algebraic form of the coefficients, which are known to be rational functions of R, by generalization from the numerical results. This technique will be useful in other higher-order perturbation calculations. The cluster properties of the F(4) and F(6) functions in high- J manifolds explain the major qualitative features of the behavior of the perturbations. In the high- R limit, 3 j coefficients give the positions of the clusters. Explicit expressions for these coefficients give a partial check of the present general algebraic expressions. The formalism is tested for the ?3 and ?4 bands of the SiF 4 molecule, using as data energy levels computed from the known spectroscopic parameters. Because of the different ? Coriolis coupling constants, these two cases differ markedly in the rate of convergence of the perturbation expansions. For each band, wavenumber data generated by computer diagonalization of the Hecht Hamiltonian operator are fitted using the perturbation formulas, and the results demonstrate the accuracy, reliability, and limitations in the use of this approximate treatment for the fitting of spectral lines.

  2. Langmuir Fiilms of Anthracene Derivatives on Liquid Mercury I: Symmetric Molecules

    SciTech Connect

    Tamam,L.; Kraack, H.; Sloutskin, E.; Ocko, B.; Pershan, P.; Ofer, E.; Deutsch, M.

    2007-01-01

    The structure and phase sequence of liquid-mercury-supported Langmuir films (LFs) of two symmetric acenes, anthracene and anthraquinone, were studied by surface tensiometry and X-ray diffraction. At low coverage, both form a monolayer of surface-parallel, flat-lying, molecules. At high coverage, we find a monolayer of side-lying molecules, where the molecular plane is surface-normal, and the molecular long axis is surface-parallel. None of these phases exhibit long-range in-plane order.

  3. Inducing changes in the bond length of diatomic molecules by time-symmetric chirped pulses

    SciTech Connect

    Chang, Bo Y.; Shin, Seokmin; Sola, Ignacio R. [School of Chemistry (BK21), Seoul National University, Seoul 151-747 (Korea, Republic of); Departamento de Quimica Fisica, Universidad Complutense, E-28040 Madrid (Spain)

    2010-12-15

    We show numerically that it is possible to change the structure of a simple molecule, that is, a diatomic molecule, where the bond length is modified at a precise timing with symmetrically chirped laser pulses. In the adiabatic regime, the process is fully time reversible, making it possible to design slow vibrations with large bond elongations. The scheme relies on the preparation of a separable state of both nuclear and electronic degrees of freedom with predominant amplitude on the dissociative (antibonding) electronic wave function. Shorter laser pulses can be used to dynamically induce larger bond elongations, preparing a highly excited vibrational wave packet in the ground potential as the laser is switched off.

  4. The quadrupole moments of spherical-top molecules in orbitally degenerate states

    NASA Astrophysics Data System (ADS)

    Ogurtsov, I. Ya.; Ostrovski, V. L.

    It is shown that in gases of spherical-top molecules with orbitally degenerate ground electronic terms the orientational mechanism contributes to the generation of birefringence in the presence of a non-uniform electric field. The orientation of molecules by such a field results from the existence of the non-zero quadrupole moments which are available in the molecules under consideration. The contribution to the optical anisotropy arising from the degeneracy has a complicated temperature dependence. At low temperatures, when the ground vibronic state is mainly populated, this contribution is a linear function of inverse temperature as in the case of anisotropic molecules with the symmetry lower than cubic. At intermediate and high temperatures the dependence of the optical anisotropy on T is sufficiently determined by the Jahn-Teller effect taking place when the electronic state has orbital degeneracy. Numerical estimation shows that the effective magnitudes of quadrupole moments of some spherical-top molecules, for example VCl4, ReF6 and IrF6 (G3/2 ground electronic term), are comparable to the quadrupole moments of the diatomic molecules.

  5. Stark-Zeeman Effects on Asymmetric Top Molecules. Formaldehyde H2CO

    Microsoft Academic Search

    Kunitaka Kondo; Takeshi Oka

    1960-01-01

    The combined Stark-Zeeman effects for asymmetric top molecules with no accidental degeneracies are studied by perturbation treatments. The theory was applied successfully to the analysis of the experimental results of Stark-Zeeman effect on the microwave spectrum of formaldehyde H2CO. By the influence of the electric field perpendicular to the magnetic field, split components of the transition 211--> 212 which, in

  6. Anomalous absorption in a-type asymmetric top molecules in cosmic objects

    NASA Astrophysics Data System (ADS)

    Chandra, Suresh

    Since the detection of the first molecule OH in cosmic objects in 1963, scientists got interested in identification of molecules in the cosmic objects. By now more than 170 molecules have been identified. In order to know about the physical conditions prevailing in the cool cosmic objects and about the chemical reactions going on there, scientists are interested in identification of as many molecules as possible. In some molecular clouds, the kinetic temperature is very low, 10 - 20 K. For such objects, anomalous absorption, i.e., the absorption against the cosmic microwave background, may play an important role for identification of molecules. The transition 111 - 110 at 4.829 GHz of H_2CO was the first one showing the anomalous absorption in the cosmic objects. The molecule H_2CS also has been identified in the cosmic objects. We have discussed about the anomalous absorption of 111 - 110 transition in a-type asymmetric top molecules. For the investigation, the required parameters are the radiative and collisional transition probabilities. We can calculate radiative transition probabilities between the rotational levels. Calculation of collisional rates is a tedious job. In absence of accurate collisional rates, we can investigated the anomalous absorption in a qualitative manner by using the scaled values for collisional rates. We find that anomalous absorption of 111 - 110 transition is possible, provided collisional rates satisfy the required condition.

  7. Designing proteins from simple motifs: opportunities in Top-Down Symmetric Deconstruction.

    PubMed

    Blaber, Michael; Lee, Jihun

    2012-08-01

    The purpose of this review is to describe the development of 'top-down' approaches to protein design. It will be argued that a diverse number of studies over the past decade, involving many investigators, and focused upon elucidating the role of symmetry in protein evolution and design, are converging into a novel top-down approach to protein design. Top-down design methodologies have successfully produced comparatively simple polypeptide 'building blocks' (typically comprising 40-60 amino acids) useful in generating complex protein architecture, and have produced compelling data in support of macro-evolutionary pathways of protein structure. Furthermore, a distillation of the experimental approaches utilized in such studies suggests the potential for method formalism, one that may accelerate future success in this field. PMID:22726756

  8. Charge symmetric dissociation of doubly ionized N2 and CO molecules.

    PubMed

    Pandey, A; Bapat, B; Shamasundar, K R

    2014-01-21

    We report a comparative study of the features in dissociative double ionization by high energy electron impact of N2 and CO molecules. The ratio of cross-section of charge symmetric dissociative ionization to non-dissociative ionization (CSD-to-ND ratio) and the kinetic energy release (KER) spectra of dissociation are experimentally measured and carefully corrected for various ion transmission losses and detector inefficiencies. Given that the double ionization cross sections of these iso-electronic diatomics are very similar, the large difference in the CSD-to-ND ratios must be attributable to the differences in the evolution dynamics of the dications. To understand these differences, potential energy curves (PECs) of dications have been computed using multi-reference configuration interaction method. The Franck-Condon factors and tunneling life times of vibrational levels of dications have also been computed. While the KER spectrum of N2 (++) can be readily explained by considering dissociation via repulsive states and tunneling of meta-stable states, indirect dissociation processes such as predissociation and autoionization have to be taken into account to understand the major features of the KER spectrum of CO(++). Direct and indirect processes identified on the basis of the PECs and experimental KER spectra also provide insights into the differences in the CSD-to-ND ratios. PMID:25669391

  9. Collision-induced absorption in mixtures of symmetrical linear and tetrahedral molecules - Methane-nitrogen

    NASA Technical Reports Server (NTRS)

    Birnbaum, G.; Borysow, A.; Buechele, A.

    1993-01-01

    The far infrared absorption of a CH4-N2 mixture was measured at 297, 195, and 162 K from 30 to 650/cm. The spectral invariants gamma1 and alpha1, proportional, respectively, to the zeroth and first spectral moments, due to bimolecular collisions between CH4 and N2 were obtained from these data and compared with theoretical values. The theory for collision-induced dipoles between a tetrahedral and a diatomic or symmetrical linear molecule includes contributions not previously considered. Whereas the theoretical values of gamma1 are only somewhat greater than experiment at all temperatures, the theoretical values of alpha1 are significantly lower than the experimental values. From the theoretical spectral moments for the various induced dipole components, the parameters of the BC shape were computed, and theoretical spectra were constructed. Good agreement was obtained at the lower frequencies, but with increasing frequencies the theoretical spectra were increasingly less intense than the experimental spectra. Although the accuracy of the theoretical results may suffer from the lack of a reliable potential function, it does not appear that this high frequency discrepancy can be removed by any conceivable modification in the potential.

  10. Charge symmetric dissociation of doubly ionized N2 and CO molecules

    NASA Astrophysics Data System (ADS)

    Pandey, A.; Bapat, B.; Shamasundar, K. R.

    2014-01-01

    We report a comparative study of the features in dissociative double ionization by high energy electron impact of N2 and CO molecules. The ratio of cross-section of charge symmetric dissociative ionization to non-dissociative ionization (CSD-to-ND ratio) and the kinetic energy release (KER) spectra of dissociation are experimentally measured and carefully corrected for various ion transmission losses and detector inefficiencies. Given that the double ionization cross sections of these iso-electronic diatomics are very similar, the large difference in the CSD-to-ND ratios must be attributable to the differences in the evolution dynamics of the dications. To understand these differences, potential energy curves (PECs) of dications have been computed using multi-reference configuration interaction method. The Franck-Condon factors and tunneling life times of vibrational levels of dications have also been computed. While the KER spectrum of N_2^{++} can be readily explained by considering dissociation via repulsive states and tunneling of meta-stable states, indirect dissociation processes such as predissociation and autoionization have to be taken into account to understand the major features of the KER spectrum of CO++. Direct and indirect processes identified on the basis of the PECs and experimental KER spectra also provide insights into the differences in the CSD-to-ND ratios.

  11. Top

    Microsoft Academic Search

    Mo Chen; Zixi Jia; Yu Gu; Ge Yu

    2011-01-01

    \\u000a An important topic in the field of spatial data management is processing the queries involving uncertain locations. This paper\\u000a focuses on the problem of finding probabilistic K closest pairs between two uncertain spatial datasets, namely, Top-K probabilistic closest pairs (TopK-PCP) query, which has popular usages in real applications. Specifically, given two uncertain datasets in which each spatial\\u000a object is modeled

  12. Tops

    NSDL National Science Digital Library

    Watsonville Environmental Science Workshop

    2011-01-01

    In this activity, learners discover that some things only stand up while they are spinning. To explore this phenomenon, learners build tops from household items such as CD's, paper plates, cups, and craft sticks. Learners will discover that the weight and radius of each top plays a role in the amount of momentum it has to spin. The launcher is also used to demonstrate one of the simple machines of physics: the wheel. Basic tools (e.g. drill) and plaster are required.

  13. Perturbation Theory for Nematic Liquid Crystals of Axially Symmetric Molecules: II. Effect of Quadrupolar Forces

    Microsoft Academic Search

    S. Singh; K. Singh

    1983-01-01

    A statistical mechanical perturbation theory, that derives from the work of Singh and Singh, is applied to analyse the influence of quadrupole interaction on a variety of thermodynamic properties of nematic liquid crystals. Numerical evaluations are done for a model system in which molecules are assumed to interact via a pair potential having both repulsive and attractive parts. The repulsive

  14. An analysis of normal and local mode dynamics based on periodic orbits. I. Symmetric ABA triatomic molecules

    NASA Astrophysics Data System (ADS)

    Stefanski, Krzysztof; Pollak, Eli

    1987-07-01

    This paper shows how to quantize Hamiltonians of symmetric ABA molecules using energies and stability frequencies of simple normal and local mode periodic orbits. It is shown that the quantization can be based either on the idea of adiabatic dynamical potentials or on the hindered rotor representation. In the former case, the stable periodic orbits correspond to the wells and the unstable ones to the barriers of the adiabatic potentials. In the latter case the normal mode periodic orbits correspond to the equilibria of the hindered rotor Hamiltonian, and the local mode periodic orbits correspond to the rotor's orbits with the maximal allowed ``angular momentum.'' Results of extensive numerical testing of both approaches are presented for the H2O model Hamiltonian used by Sibert et al., and for the Davis-Heller potential.

  15. Microwave spectrum of two top molecules in the excited states dimethyl ether, dimethyl sulfide, and dimethyl silane

    NASA Astrophysics Data System (ADS)

    Niide, Yuzuru; Hayashi, Michiro

    2004-02-01

    Microwave spectra of dimethyl ether, dimethyl sulfide, and dimethyl silane in the torsionally excited states have been measured. The methyl internal rotations of these molecules were analyzed from the observed multiplets and from the reported multiplets of transitions. The method developed for ethyl silane in the previous paper was extended to equivalent two top molecules. For equivalent two top molecules, apparent barriers of methyl internal rotations obtained from the experiments were corrected by the kinetic and potential cross terms. They are V3=2645.8±10.0, 2632.4 ± 42.9, 2146.0 ± 13.8, 1651.5 ± 10.1, 1648.0 ± 13.7, and 1649.9 ± 11.8 cal/mol for (CH 3) 2O, (CD 3) 2O, (CH 3) 2S, (CH 3) 2SiH 2, (CH 3) 2SiD 2, and (CH 3) 2SiHD, respectively. The potential cross terms, V12(1-cos3 ?1)(1-cos3 ?2) terms are negligible for the three molecules, while V'12sin3 ?1sin3 ?2 terms are also very close to zero except those for (CH 3) 2O and (CD 3) 2O which are small but not negligible ( V'12=-124.4,-158.0 cal/mol). The investigations were extended to those of non-equivalent two top species and the corrected barriers of the methyl tops, V3, are obtained to be 2615.6 ± 8.6 and 2155.0 ± 15.2 cal/mol for CH 3OCD 3 and CH 3SCD 3. The corrected barrier, V3(CD 3) of CH 3OCD 3, is obtained to be 2634.4 ± 7.1 cal/mol, while that of CH 3SCD 3 cannot be solved due to the lack of the data available.

  16. Ionization of one- and three-dimensionally-oriented asymmetric-top molecules by intense circularly polarized femtosecond laser pulses

    SciTech Connect

    Hansen, Jonas L. [Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus C (Denmark); Holmegaard, Lotte; Kalhoej, Line; Kragh, Sofie Louise [Department of Chemistry, Aarhus University, DK-8000 Aarhus C (Denmark); Stapelfeldt, Henrik [Department of Chemistry, Aarhus University, DK-8000 Aarhus C (Denmark); Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus C (Denmark); Filsinger, Frank; Meijer, Gerard; Kuepper, Jochen; Dimitrovski, Darko; Abu-samha, Mahmoud; Martiny, Christian Per Juul; Madsen, Lars Bojer [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany); Lundbeck Foundation Theoretical Center for Quantum System Research, Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark)

    2011-02-15

    We present a combined experimental and theoretical study on strong-field ionization of a three-dimensionally-oriented asymmetric top molecule, benzonitrile (C{sub 7}H{sub 5}N), by circularly polarized, nonresonant femtosecond laser pulses. Prior to the interaction with the strong field, the molecules are quantum-state selected using a deflector and three-dimensionally (3D) aligned and oriented adiabatically using an elliptically polarized laser pulse in combination with a static electric field. A characteristic splitting in the molecular frame photoelectron momentum distribution reveals the position of the nodal planes of the molecular orbitals from which ionization occurs. The experimental results are supported by a theoretical tunneling model that includes and quantifies the splitting in the momentum distribution. The focus of the present article is to understand strong-field ionization from 3D-oriented asymmetric top molecules, in particular the suppression of electron emission in nodal planes of molecular orbitals. In the preceding article [Dimitrovski et al., Phys. Rev. A 83, 023405 (2011)] the focus is to understand the strong-field ionization of one-dimensionally-oriented polar molecules, in particular asymmetries in the emission direction of the photoelectrons.

  17. Many-photon excitation of spherically symmetric molecules in an infrared laser field by weakly forbidden DeltaR!=0, Deltan!=0 vibrational-rotational transitions

    Microsoft Academic Search

    I. N. Knyazev; V. V. Lobko

    1980-01-01

    An analysis is made of a model of multistage excitation of triply degenerate vibrations of spherically symmetric molecules in a strong infrared laser field. This involves allowing for weakly forbidden DeltaR!=0, Deltan!=0 transitions. It is shown that as a result of these transitions, a system of up to several dozen multistage resonances is established within the absorption band. These resonances

  18. Calculation of Anharmonicities in Overtone Modes and Small-Cluster Shifts of Spherical-Top Molecules

    NASA Astrophysics Data System (ADS)

    Fuhr, Javier D.; Fiol, Juan; Cortizo, Eduardo; Fainstein, Pablo D.; Fregenal, Daniel E.; Guozden, Tomás; Kaúl, Enrique; Knoblauch, Pablo; Lamagna, Alberto; Maceira, Pablo; Rozas, Guillermo; Zarco, Martín

    2014-06-01

    Harmonic and anharmonic vibrational self-consistent field (VSCF) calculations were employed to investigate the fundamental and overtone modes of SF6 molecules. Determination of the Potential Energy Surface (PES) on a multidimensional grid of more than 65000 nodes was performed, and a system of 1D coupled-equations was solved. Corrections to the harmonic approximation for the frequencies of the fundamental modes and their overtones were obtained. Ab-initio calculations to the interaction potential between two molecules as a function of their position and orientation, and the corresponding energies for dimer formation, have been computed. Finally, the effect of dimerization on the molecular frequencies is investigated.

  19. A missing link in the transformation from asymmetric to symmetric metallofullerene cages implies a top-down fullerene formation mechanism.

    PubMed

    Zhang, Jianyuan; Bowles, Faye L; Bearden, Daniel W; Ray, W Keith; Fuhrer, Tim; Ye, Youqing; Dixon, Caitlyn; Harich, Kim; Helm, Richard F; Olmstead, Marilyn M; Balch, Alan L; Dorn, Harry C

    2013-10-01

    Although fullerenes were discovered nearly three decades ago, the mechanism of their formation remains a mystery. Many versions of the classic 'bottom-up' formation mechanism have been advanced, starting with C2 units that build up to form chains and rings of carbon atoms and ultimately form those well-known isolated fullerenes (for example, I(h)-C60). In recent years, evidence from laboratory and interstellar observations has emerged to suggest a 'top-down' mechanism, whereby small isolated fullerenes are formed via shrinkage of giant fullerenes generated from graphene sheets. Here, we present molecular structural evidence for this top-down mechanism based on metal carbide metallofullerenes M2C2@C1(51383)-C84 (M = Y, Gd). We propose that the unique asymmetric C1(51383)-C84 cage with destabilizing fused pentagons is a preserved 'missing link' in the top-down mechanism, and in well-established rearrangement steps can form many well-known, high-symmetry fullerene structures that account for the majority of solvent-extractable metallofullerenes. PMID:24056346

  20. Theoretical study of two-photon absorption properties and up-conversion efficiency of new symmetric organic ?-conjugated molecules for photovoltaic devices.

    PubMed

    Hu, Zhong; Khadka, Vedbar S; Wang, Wei; Galipeau, David W; Yan, Xingzhong

    2012-08-01

    Organic material with high intensity of two-photon absorption (TPA) induced fluorescence can be used as the frequency up-converter materials for improving efficiency of the solar cells. In this work, the organic molecular structures were designed by symmetrically grafting two elongated conjugated linkers on a conjugated core and then adding donor groups at both terminals. Fluorene derivatives as a core acceptor, phenylethynyl as the conjugated linker and diphenylamino or methyl-9H-carbozole as the donor end groups were selected. Quantum mechanical modeling techniques were applied to investigate the molecular electronic structure and properties. Absorption properties of these novel ?-conjugated organic molecules were studied. The TPA cross-sections of these derivatives were calculated using few-states models, respectively. The effects of donor and acceptor groups on the TPA behaviors of these designed molecules were investigated. The up-conversion efficiency of designed molecules was also calculated. PMID:22358392

  1. Molecules

    NSDL National Science Digital Library

    1995-01-01

    The Switzerland-based society, Molecular Diversity Preservation International (MDPI) provides this free, online journal, Molecules. This journal of synthetic and natural product chemistry encourages chemists to publish their experimental detail, particularly synthetic procedures and characterization information. "Any scattered unassembled experimental data for individual compounds which is conventionally not publishable is particularly welcomed," says the site. The idea is to get information out as quickly as possible to the scientific community. To access Molecules, follow the instructions on how to request a username and password.

  2. Hierarchical chiral expression from the nano- to mesoscale in synthetic supramolecular helical fibers of a nonamphiphilic C3-symmetrical ?-functional molecule.

    PubMed

    Danila, Ion; Riobé, François; Piron, Flavia; Puigmartí-Luis, Josep; Wallis, John D; Linares, Mathieu; Ågren, Hans; Beljonne, David; Amabilino, David B; Avarvari, Narcis

    2011-06-01

    The controlled preparation of chiral structures is a contemporary challenge for supramolecular science because of the interesting properties that can arise from the resulting materials, and here we show that a synthetic nonamphiphilic C(3) compound containing ?-functional tetrathiafulvalene units can form this kind of object. We describe the synthesis, characterization, and self-assembly properties in solution and in the solid state of the enantiopure materials. Circular dichroism (CD) measurements show optical activity resulting from the presence of twisted stacks of preferential helicity and also reveal the critical importance of fiber nucleation in their formation. Molecular mechanics (MM) and molecular dynamics (MD) simulations combined with CD theoretical calculations demonstrate that the (S) enantiomer provides the (M) helix, which is more stable than the (P) helix for this enantiomer. This relationship is for the first time established in this family of C(3) symmetric compounds. In addition, we show that introduction of the "wrong" enantiomer in a stack decreases the helical reversal barrier in a nonlinear manner, which very probably accounts for the absence of a "majority rules" effect. Mesoscopic chiral fibers, which show inverted helicity, i.e. (P) for the (S) enantiomer and (M) for the (R) one, have been obtained upon reprecipitation from dioxane and analyzed by optical and electronic microscopy. The fibers obtained with the racemic mixture present, as a remarkable feature, opposite homochiral domains within the same fiber, separated by points of helical reversal. Their formation can be explained through an "oscillating" crystallization mechanism. Although C(3) symmetric disk-shaped molecules containing a central benzene core substituted in the 1,3,5 positions with 3,3'-diamido-2,2'-bipyridine based wedges have shown peculiar self-assembly properties for amphiphilic derivatives, the present result shows the benefits of reducing the nonfunctional part of the molecule, in our case with short chiral isopentyl chains. The research reported herein represents an important step toward the preparation of functional mesostructures with controlled helical architectures. PMID:21517038

  3. A spray-coating process for highly conductive silver nanowire networks as the transparent top-electrode for small molecule organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Selzer, Franz; Weiß, Nelli; Kneppe, David; Bormann, Ludwig; Sachse, Christoph; Gaponik, Nikolai; Eychmüller, Alexander; Leo, Karl; Müller-Meskamp, Lars

    2015-01-01

    We present a novel top-electrode spray-coating process for the solution-based deposition of silver nanowires (AgNWs) onto vacuum-processed small molecule organic electronic solar cells. The process is compatible with organic light emitting diodes (OLEDs) and organic light emitting thin film transistors (OLETs) as well. By modifying commonly synthesized AgNWs with a perfluorinated methacrylate, we are able to disperse these wires in a highly fluorinated solvent. This solvent does not dissolve most organic materials, enabling a top spray-coating process for sensitive small molecule and polymer-based devices. The optimized preparation of the novel AgNW dispersion and spray-coating at only 30 °C leads to high performance electrodes directly after the deposition, exhibiting a sheet resistance of 10.0 ? ?-1 at 87.4% transparency (80.0% with substrate). By spraying our novel AgNW dispersion in air onto the vacuum-processed organic p-i-n type solar cells, we obtain working solar cells with a power conversion efficiency (PCE) of 1.23%, compared to the air exposed reference devices employing thermally evaporated thin metal layers as the top-electrode.We present a novel top-electrode spray-coating process for the solution-based deposition of silver nanowires (AgNWs) onto vacuum-processed small molecule organic electronic solar cells. The process is compatible with organic light emitting diodes (OLEDs) and organic light emitting thin film transistors (OLETs) as well. By modifying commonly synthesized AgNWs with a perfluorinated methacrylate, we are able to disperse these wires in a highly fluorinated solvent. This solvent does not dissolve most organic materials, enabling a top spray-coating process for sensitive small molecule and polymer-based devices. The optimized preparation of the novel AgNW dispersion and spray-coating at only 30 °C leads to high performance electrodes directly after the deposition, exhibiting a sheet resistance of 10.0 ? ?-1 at 87.4% transparency (80.0% with substrate). By spraying our novel AgNW dispersion in air onto the vacuum-processed organic p-i-n type solar cells, we obtain working solar cells with a power conversion efficiency (PCE) of 1.23%, compared to the air exposed reference devices employing thermally evaporated thin metal layers as the top-electrode. Electronic supplementary information (ESI) available: XPS and SEM data clarifying the crucial role of the amount of stabilizer on sheet resistance; j-V-data of the annealed air cell enabling a deeper understanding of the influence of air exposure. See DOI: 10.1039/c4nr06502f.

  4. Enhanced ionization of the non-symmetric HeH{sup +} molecule driven by intense ultrashort laser pulses

    SciTech Connect

    Dehghanian, E. [Department of Chemistry, University of Sistan and Baluchestan, Zahedan 98155-987 (Iran, Islamic Republic of)] [Department of Chemistry, University of Sistan and Baluchestan, Zahedan 98155-987 (Iran, Islamic Republic of); Bandrauk, A. D. [Département de Chimie, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1 (Canada)] [Département de Chimie, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1 (Canada); Lagmago Kamta, G. [Cancer Research Institute, Hopital C. LeMoyne, Greenfield Park, Québec J4V 2H1 (Canada)] [Cancer Research Institute, Hopital C. LeMoyne, Greenfield Park, Québec J4V 2H1 (Canada)

    2013-08-28

    We study enhanced single and double ionizations and enhanced single and double excitations in the nonsymmetric two-electron diatomic molecular ion HeH{sup +} in an intense ultrashort laser pulse linearly polarized along the internuclear axis (z axis). We solve a three-dimensional time-dependent Schrödinger equation, TDSE, via correlated two-electron ab initio calculations within the fixed-nuclei approximation. A complex scaling method is used for calculation of both single and double ionizations. These nonperturbative processes increase with large internuclear distance R and reach a maximum at some critical distance R{sub c} and decrease by further increase of R. This enhanced ionization (EI) at R{sub c} is accompanied by enhanced single and double excitation processes. Furthermore, EI is stronger when the permanent dipole moment of the molecule and the electric field at the peak of the laser pulse are antiparallel than when they are parallel. We predict analytically the R{sub c} at which the enhancement of all these molecular processes happens in HeH{sup +} from a simple quasistatic model and investigate the effect of Carrier Envelope Phase on these nonlinear nonperturbative processes.

  5. Disappearance of Schwinger's string at the charge - monopole "molecule"

    E-print Network

    S. E. Korenblit; Kieun Lee

    2010-03-07

    An equivalence of total momentum operator of charge - monopole system to the momentum operator of a symmetrical quantum top is observed. This explicitly shows the string independence of Dirac's quantization condition leading to disappearance of Schwinger's string and reveals some properties of diatomic molecule for this system.

  6. On-top ?-stacking of quasiplanar molecules in hole-transporting materials: inducing anisotropic carrier mobility in amorphous films.

    PubMed

    Wakamiya, Atsushi; Nishimura, Hidetaka; Fukushima, Tatsuya; Suzuki, Furitsu; Saeki, Akinori; Seki, Shu; Osaka, Itaru; Sasamori, Takahiro; Murata, Michihisa; Murata, Yasujiro; Kaji, Hironori

    2014-06-01

    Dimers of partially oxygen-bridged triarylamines were designed and synthesized as hole-transporting materials. X-ray structural analyses revealed that these compounds form on-top ?-stacking aggregates in the crystalline state. TRMC measurements showed that high levels of anisotropic charge transport were induced in the direction of the ?-stacking. Surprisingly, even in vacuum-deposited amorphous films, these compounds retained some of the face-on ?-stacking, thus facilitating an out-of-plane carrier mobility. PMID:24764307

  7. Stability of localized quantum states on the top of a barrier and some of its consequences: the specific case of a symmetric double well potential

    Microsoft Academic Search

    S. Adhikari; S. P. Bhattacharyya; P. Dutta

    1996-01-01

    It is demonstrated that barriers, like potential wells, can support localised states. However, barrier-localized states are seen to be much more short-lived compared to states localised in potential wells. These features are revealed with reference to a symmetric double-well potential by using the exterior complex-scaled Fourier grid Hamiltonian method. Some implications of the results are pointed out.

  8. Rotational spectroscopy as a tool to investigate interactions between vibrational polyads in symmetric top molecules: low-lying states v8 <= 2 of methyl cyanide, CH$_3$CN

    E-print Network

    Müller, Holger S P; Drouin, Brian J; Pearson, John C; Kleiner, Isabelle; Sams, Robert L; Sung, Keeyoon; Ordu, Matthias H; Lewen, Frank

    2015-01-01

    Spectra of methyl cyanide were recorded to analyze interactions in low-lying vibrational states and to construct line lists for radio astronomical observations as well as for infrared spectroscopic investigations of planetary atmospheres. The rotational spectra cover large portions of the 36-1627 GHz region. In the infrared (IR), a spectrum was recorded for this study in the region of 2nu8 around 717 cm-1 with assignments covering 684-765 cm-1. Additional spectra in the nu8 region were used to validate the analysis. The large amount and the high accuracy of the rotational data extend to much higher J and K quantum numbers and allowed us to investigate for the first time in depth local interactions between these states which occur at high K values. In particular, we have detected several interactions between v8 = 1 and 2. Notably, there is a strong Delta(v8) = +- 1, Delta(K) = 0, Delta(l) = +-3 Fermi resonance between v8 = 1^-1 and v8 = 2^+2 at K = 14. Pronounced effects in the spectrum are also caused by reso...

  9. Adiabatic orientation of rotating dipole molecules in an external field

    E-print Network

    Bulthuis, J; Moro, R; Kresin, V V

    2008-01-01

    The induced polarization of a beam of polar clusters or molecules passing through an electric or magnetic field region differs from the textbook Langevin-Debye susceptibility. This distinction, which is important for the interpretation of deflection and focusing experiments, arises because instead of acquiring thermal equilibrium in the field region, the beam ensemble typically enters the field adiabatically, i.e., with a previously fixed distribution of rotational states. We discuss the orientation of rigid symmetric-top systems with a body-fixed electric or magnetic dipole moment. The analytical expression for their "adiabatic-entry" orientation is elucidated and compared with exact numerical results for a range of parameters. The differences between the polarization of thermodynamic and "adiabatic-entry" ensembles, of prolate and oblate tops, and of symmetric-top and linear rotators are illustrated and identified.

  10. Opto-Electrical Cooling of Polar Molecules

    E-print Network

    M. Zeppenfeld; M. Motsch; P. W. H. Pinkse; G. Rempe

    2009-10-07

    We present an opto-electrical cooling scheme for polar molecules based on a Sisyphus-type cooling cycle in suitably tailored electric trapping fields. Dissipation is provided by spontaneous vibrational decay in a closed level scheme found in symmetric-top rotors comprising six low-field-seeking rovibrational states. A generic trap design is presented. Suitable molecules are identified with vibrational decay rates on the order of 100Hz. A simulation of the cooling process shows that the molecular temperature can be reduced from 1K to 1mK in approximately 10s. The molecules remain electrically trapped during this time, indicating that the ultracold regime can be reached in an experimentally feasible scheme.

  11. Two dimensional symmetric correlation functions of the ? operator and two dimensional Fourier transforms: considering the line coupling for P and R lines of linear molecules.

    PubMed

    Ma, Q; Boulet, C; Tipping, R H

    2014-03-14

    The refinement of the Robert-Bonamy (RB) formalism by considering the line coupling for isotropic Raman Q lines of linear molecules developed in our previous study [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)] has been extended to infrared P and R lines. In these calculations, the main task is to derive diagonal and off-diagonal matrix elements of the Liouville operator iS1 - S2 introduced in the formalism. When one considers the line coupling for isotropic Raman Q lines where their initial and final rotational quantum numbers are identical, the derivations of off-diagonal elements do not require extra correlation functions of the ? operator and their Fourier transforms except for those used in deriving diagonal elements. In contrast, the derivations for infrared P and R lines become more difficult because they require a lot of new correlation functions and their Fourier transforms. By introducing two dimensional correlation functions labeled by two tensor ranks and making variable changes to become even functions, the derivations only require the latters' two dimensional Fourier transforms evaluated at two modulation frequencies characterizing the averaged energy gap and the frequency detuning between the two coupled transitions. With the coordinate representation, it is easy to accurately derive these two dimensional correlation functions. Meanwhile, by using the sampling theory one is able to effectively evaluate their two dimensional Fourier transforms. Thus, the obstacles in considering the line coupling for P and R lines have been overcome. Numerical calculations have been carried out for the half-widths of both the isotropic Raman Q lines and the infrared P and R lines of C2H2 broadened by N2. In comparison with values derived from the RB formalism, new calculated values are significantly reduced and become closer to measurements. PMID:24628166

  12. Two Dimensional Symmetric Correlation Functions of the S Operator and Two Dimensional Fourier Transforms: Considering the Line Coupling for P and R Lines of Linear Molecules

    NASA Technical Reports Server (NTRS)

    Ma, Q.; Boulet, C.; Tipping, R. H.

    2014-01-01

    The refinement of the Robert-Bonamy (RB) formalism by considering the line coupling for isotropic Raman Q lines of linear molecules developed in our previous study [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)] has been extended to infrared P and R lines. In these calculations, the main task is to derive diagonal and off-diagonal matrix elements of the Liouville operator iS1 - S2 introduced in the formalism. When one considers the line coupling for isotropic Raman Q lines where their initial and final rotational quantum numbers are identical, the derivations of off-diagonal elements do not require extra correlation functions of the ^S operator and their Fourier transforms except for those used in deriving diagonal elements. In contrast, the derivations for infrared P and R lines become more difficult because they require a lot of new correlation functions and their Fourier transforms. By introducing two dimensional correlation functions labeled by two tensor ranks and making variable changes to become even functions, the derivations only require the latters' two dimensional Fourier transforms evaluated at two modulation frequencies characterizing the averaged energy gap and the frequency detuning between the two coupled transitions. With the coordinate representation, it is easy to accurately derive these two dimensional correlation functions. Meanwhile, by using the sampling theory one is able to effectively evaluate their two dimensional Fourier transforms. Thus, the obstacles in considering the line coupling for P and R lines have been overcome. Numerical calculations have been carried out for the half-widths of both the isotropic Raman Q lines and the infrared P and R lines of C2H2 broadened by N2. In comparison with values derived from the RB formalism, new calculated values are significantly reduced and become closer to measurements.

  13. Orientation of dipole molecules and clusters upon adiabatic entry into an external field.

    PubMed

    Bulthuis, J; Becker, J A; Moro, R; Kresin, V V

    2008-07-14

    The induced polarization of a beam of polar clusters or molecules passing through an electric or magnetic field region differs from the textbook Langevin-Debye susceptibility. This distinction, which is important for the interpretation of deflection and focusing experiments, arises because instead of acquiring thermal equilibrium in the field region, the beam ensemble typically enters the field adiabatically, i.e., with a previously fixed distribution of rotational states. We discuss the orientation of rigid symmetric top systems with a body-fixed electric or magnetic dipole moment. The analytical expression for their "adiabatic-entry" orientation is elucidated and compared with exact numerical results for a range of parameters. The differences between the polarization of thermodynamic and "adiabatic-entry" ensembles of prolate and oblate tops, and of symmetric top and linear rotators, are illustrated and identified. PMID:18624510

  14. Beam broadening of polar molecules and clusters in deflection experiments.

    PubMed

    Bulthuis, J; Kresin, V V

    2012-01-01

    A beam of rotating dipolar particles (molecules or clusters) will broaden when passed through an electric or magnetic field gradient region. This broadening, which is a common experimental observable, can be expressed in terms of the variance of the distribution of the resulting polarization orientation (the direction cosine). Here, the broadening for symmetric-top and linear rotors is discussed. These two types of rotors have qualitatively different low-field orientation distribution functions, but behave similarly in a strong field. While analytical expressions for the polarization variance can be derived from first-order perturbation theory, for experimental guidance it is important to identify the applicability and limitations of these expressions, and the general dependence of the broadening on the experimental parameters. For this purpose, the analytical results are compared with the full diagonalization of the rotational Stark-effect matrices. Conveniently for experimental estimations, it is found that for symmetric tops, the dependence of the broadening parameter on the rotational constant, the axial ratio, and the field strength remains similar to the analytical expression even outside of the perturbative regime. Also, it is observed that the shape envelope, the centroid, and the width of the orientation distribution function for a symmetric top are quite insensitive to the value of its rotational constant (except at low rotational temperatures). PMID:22239775

  15. Theoretical study of the effects of di-muonic molecules on muon-catalyzed fusion

    NASA Astrophysics Data System (ADS)

    Sheely, Eugene V.

    This document presents a theoretical study di-muonic hydrogen and helium molecules that have the potential of enhancing the muon-catalyzed fusion reaction rate. In order to study these di-muonic molecules a method of non-adiabatic quantum mechanics referred to as a General Particle Orbital (GPO) method was developed. Three mechanisms that have the possibility of enhancing the muon-catalyzed fusion rate were discovered. Two involve the formation of di-muonic hydrogen molecules, and the other uses di-muonic molecules to liberate muons stuck to 3He nuclei. The effects of muon spin on di-muonic hydrogen molecules was studied. The nuclear separation in di-muonic hydrogen molecules with parallel muon spin is too great for the molecules to have a fusion rate which can enhance the fusion yield. The possibility of these molecules transitioning to single muon molecules or triatomic oblate symmetric top molecules which may fuse faster is examined. Using two muons to catalyze 3He-3He fusion is shown to be impractical; however, using two muons to catalyze 3He-d fusion is possible. While studying the physical properties of di-muonic hydrogen and helium molecules some unique properties were discovered. Correlation interactions in these molecules result in an increase in the calculated nuclear bond length.

  16. Oriented Molecule Interactions with Atoms and Surfaces.

    NASA Astrophysics Data System (ADS)

    Mackay, R. Scott

    Mutual orientation of reagents is second only to the energy requirement for a chemical reaction to take place. Since the introduction of the hexapole field focusing and orientation of symmetric-top molecules in 1965, considerable insight has been gained on the role of orientation in reactive scattering dynamics. The degree of laboratory orientation has been measured for (CH_3) _3CBr and has been found to follow the sequence (CH_3)_3CBr > (CH_3) _3CI > CH_3 I for previous measurements. Oriented molecule beams of thirteen different molecules have been scattered by a graphite(0001) surface. The results show a large diversity in the sign and magnitude of the steric effect (i.e., "heads" vs. "tails"). It appears from the bulk of data that the origin of the steric effect is the anisotropic molecule-graphite interaction potential, which is governed by the charge density distribution of the molecule. The steric effects have been quantitatively measured for seven of the molecules and have been analyzed in terms of a two component model which yields estimates for the anisotropy of the trapping probability. An effusive oven of Sr was used in a crossed beam reaction of Sr + CH_3I. In order to detect weak product signal, a sensitive detection technique utilizing single photon ionization of the reaction product was developed. By changing the relative velocity of the reactants, the excitation function (reactive cross section vs. collision energy) was measured. The experimental results were simulated by a modified angle dependent line -of-centers model, which gives the reaction potential energy surface. Excitation functions of other alkyl halides reactions, Sr + RX (R = H, CH_3, C_2H _5,C_3H_7, C_4H_9; X = Br, I), were also explored.

  17. Analytical Morse/long-Range model potential and predicted infrared and microwave spectra for a symmetric top-atom dimer: A case study of CH{sub 3}F–He

    SciTech Connect

    Ma, Yong-Tao; Li, Hui, E-mail: Prof-huili@jlu.edu.cn [Institute of Theoretical Chemistry, State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, 2519 Jiefang Road, Changchun 130023 (China); Zeng, Tao [Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853 (United States)

    2014-06-07

    Four-dimensional ab initio intermolecular potential energy surfaces (PESs) for CH{sub 3}F–He that explicitly incorporates dependence on the Q{sub 3} stretching normal mode of the CH{sub 3}F molecule and are parametrically dependent on the other averaged intramolecular coordinates have been calculated. Analytical three-dimensional PESs for v{sub 3}(CH{sub 3}F) = 0 and 1 are obtained by least-squares fitting the vibrationally averaged potentials to the Morse/Long-Range potential function form. With the 3D PESs, we employ Lanczos algorithm to calculate rovibrational levels of the dimer system. Following some re-assignments, the predicted transition frequencies are in good agreement with experimental microwave data for ortho-CH{sub 3}F, with the root-mean-square deviation of 0.042 cm{sup ?1}. We then provide the first prediction of the infrared and microwave spectra for the para-CH{sub 3}F–He dimer. The calculated infrared band origin shifts associated with the ?{sub 3} fundamental of CH{sub 3}F are 0.039 and 0.069 cm{sup ?1} for para-CH{sub 3}F–He and ortho-CH{sub 3}F–He, respectively.

  18. Wave Engine Topping Cycle Assessment

    NASA Technical Reports Server (NTRS)

    Welch, Gerard E.

    1996-01-01

    The performance benefits derived by topping a gas turbine engine with a wave engine are assessed. The wave engine is a wave rotor that produces shaft power by exploiting gas dynamic energy exchange and flow turning. The wave engine is added to the baseline turboshaft engine while keeping high-pressure-turbine inlet conditions, compressor pressure ratio, engine mass flow rate, and cooling flow fractions fixed. Related work has focused on topping with pressure-exchangers (i.e., wave rotors that provide pressure gain with zero net shaft power output); however, more energy can be added to a wave-engine-topped cycle leading to greater engine specific-power-enhancement The energy addition occurs at a lower pressure in the wave-engine-topped cycle; thus the specific-fuel-consumption-enhancement effected by ideal wave engine topping is slightly lower than that effected by ideal pressure-exchanger topping. At a component level, however, flow turning affords the wave engine a degree-of-freedom relative to the pressure-exchanger that enables a more efficient match with the baseline engine. In some cases, therefore, the SFC-enhancement by wave engine topping is greater than that by pressure-exchanger topping. An ideal wave-rotor-characteristic is used to identify key wave engine design parameters and to contrast the wave engine and pressure-exchanger topping approaches. An aerodynamic design procedure is described in which wave engine design-point performance levels are computed using a one-dimensional wave rotor model. Wave engines using various wave cycles are considered including two-port cycles with on-rotor combustion (valved-combustors) and reverse-flow and through-flow four-port cycles with heat addition in conventional burners. A through-flow wave cycle design with symmetric blading is used to assess engine performance benefits. The wave-engine-topped turboshaft engine produces 16% more power than does a pressure-exchanger-topped engine under the specified topping constraints. Positive and negative aspects of wave engine topping in gas turbine engines are identified.

  19. Strongly exponential symmetric spaces

    E-print Network

    Yannick Voglaire

    2014-04-06

    We study the exponential map of connected symmetric spaces and characterize, in terms of midpoints and of infinitesimal conditions, when it is a diffeomorphism, generalizing the Dixmier-Saito theorem for solvable Lie groups. We then give a geometric characterization of the (strongly) exponential solvable symmetric spaces as those spaces for which every triangle admits a unique double triangle. This work is motivated by Weinstein's quantization by groupoids program applied to symmetric spaces.

  20. Geometry and bonding in the ground and lowest triplet state of D 6 h symmetric crenellated edged C 6[3 m ( m ?1)+1]H 6(2 m ?1) ( m = 2, … , 6) graphene hydrocarbon molecules

    Microsoft Academic Search

    Michael R. Philpott; Yoshiyuki Kawazoe

    2009-01-01

    Ab initio plane wave all valence electron based DFT calculations were used to explore the dichotomy of perimeter vs. interior in the electronic and geometric structure of the D6h singlet ground state and D2h lowest triplet state of planar graphene hydrocarbon molecules with crenellated (arm chair) edges and the general formula C6[3m(m?1)+1] H6(2m?1) where m=2,…,6. The largest molecule C546H66 was

  1. Noncommutative symmetric functions

    Microsoft Academic Search

    Israel Gelfand; D. Krob; Alain Lascoux; B. Leclerc; V. S. Retakh; J.-Y. Thibon

    1994-01-01

    This paper presents a noncommutative theory of symmetric functions, based on the notion of quasi-determinant. We begin with a formal theory, corresponding to the case of symmetric functions in an infinite number of independent variables. This allows us to endow the resulting algebra with a Hopf structure, which leads to a new method for computing in descent algebras. It also

  2. Symmetric network computation

    Microsoft Academic Search

    David Pritchard; Santosh Vempala

    2006-01-01

    We introduce a simple new model of distributed compu- tation | nite-state symmetric graph automata (FSSGA) | which captures the qualitative properties common to fault-tolerant distributed algorithms. Roughly speaking, the computation evolves homogeneously in the entire network, with each node acting symmetrically and with limited re- sources. As a building block, we demonstrate the equiv- alence of two automaton models

  3. Creating a Symmetrical Design

    NSDL National Science Digital Library

    National Security Agency Central Security Service

    2009-04-24

    This unit teaches students the meaning of symmetry by having them manipulate a variety of objects. Using this knowledge, they will create a symmetrical design and write an informative paragraph about the quilt design and the importance of symmetry.

  4. PT-symmetric strings

    SciTech Connect

    Amore, Paolo, E-mail: paolo.amore@gmail.com [Facultad de Ciencias, CUICBAS, Universidad de Colima, Bernal Díaz del Castillo 340, Colima, Colima (Mexico); Fernández, Francisco M., E-mail: fernande@quimica.unlp.edu.ar [INIFTA (UNLP, CCT La Plata-CONICET), División Química Teórica, Diag. 113 y 64 (S/N), Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina); Garcia, Javier [INIFTA (UNLP, CCT La Plata-CONICET), División Química Teórica, Diag. 113 y 64 (S/N), Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina); Gutierrez, German [Facultad de Ciencias, CUICBAS, Universidad de Colima, Bernal Díaz del Castillo 340, Colima, Colima (Mexico)

    2014-04-15

    We study both analytically and numerically the spectrum of inhomogeneous strings with PT-symmetric density. We discuss an exactly solvable model of PT-symmetric string which is isospectral to the uniform string; for more general strings, we calculate exactly the sum rules Z(p)??{sub n=1}{sup ?}1/E{sub n}{sup p}, with p=1,2,… and find explicit expressions which can be used to obtain bounds on the lowest eigenvalue. A detailed numerical calculation is carried out for two non-solvable models depending on a parameter, obtaining precise estimates of the critical values where pair of real eigenvalues become complex. -- Highlights: •PT-symmetric Hamiltonians exhibit real eigenvalues when PT symmetry is unbroken. •We study PT-symmetric strings with complex density. •They exhibit regions of unbroken PT symmetry. •We calculate the critical parameters at the boundaries of those regions. •There are exact real sum rules for some particular complex densities.

  5. 1 Weakly Symmetric Spaces

    E-print Network

    Ziller, Wolfgang

    well known consequence of being naturally reductive is that all geo- desics are images of one parameter] are the distance spheres in rank 1 symmetric spaces and tubes around some totally geodesic submanifolds in rank 1

  6. Beam broadening of polar molecules and clusters in deflection experiments

    E-print Network

    Bulthuis, Jaap

    2011-01-01

    A beam of rotating dipolar particles (molecules or clusters) will broaden when passed through an electric or magnetic field gradient region. This broadening, which is a common experimental observable, can be expressed in terms of the variance of the distribution of the resulting polarization orientation (the direction cosine). Here the broadening for symmetric-top and linear rotors is discussed. These two types of rotors have qualitatively different low-field orientation distribution functions, but behave similarly in a strong field. While analytical expressions for the polarization variance can be derived from first-order perturbation theory, for experimental guidance it is important to identify the applicability and limitations of these expressions, and the general dependence of the broadening on the experimental parameters. For this purpose, the analytical results are compared with the full diagonalization of the rotational Stark-effect matrices. Conveniently for experimental estimations, it is found that ...

  7. Plane Symmetric Gravitational Collapse

    E-print Network

    M. Sharif; Zahid Ahmad

    2007-09-20

    In this paper, we derive the general formulation by considering two arbitrary plane symmetric spacetimes using Israel's method. As an example, we apply this formulation to known plane symmetric spacetimes. We take the Taub's static metric in the interior region whereas Kasner's non-static metric in the exterior region. It is shown that the plane collapses in some cases whereas it expands in some other cases.

  8. Self-Assembling Dessert Toppings

    NSDL National Science Digital Library

    2012-12-27

    This is an activity (located on page 3 of the PDF) about self-assembly, the ability of molecules to assemble themselves according to certain rules. Learners will use food-grade components to create delicious dessert topping-filled gel capsules, macroscale relatives of the capsules nanoscientists make in a lab to carry medicine to targeted cells of the body. Relates to linked video, DragonflyTV Nano: Self-Assembly.

  9. Oriented molecule beams: Focusing and orientation of t-butyl iodide with analysis by polarized laser photofragmentation

    NASA Astrophysics Data System (ADS)

    Xu, Qi-Xun; Jung, Kyung-Hoon; Bernstein, Richard B.

    1988-08-01

    The tert-butyl iodide molecule is readily focused with the electrostatic hexapole, via its first-order Stark effect as a pseudo-symmetric top. The pulsed, seeded supersonic focused beam, characterized by =Vth/ V0 (where ? is the angle between the molecular dipole axis ? and the electric field E; ±V0 the hexapole ``rod voltage,'' and Vth the so-called threshold voltage), passes into a small homogeneous electric field in which it is oriented. The degree of laboratory orientation achieved is measured using the method of linearly polarized laser-induced photofragmentation [S. R. Gandhi, T. J. Curtiss, and R. B. Bernstein, Phys. Rev. Lett. 59, 2951 (1987)], operating (at three laser wavelengths) on the I(2P3/2) and I(2P1/2) as well as the t-C4H9 radical photofragments. The results show that the oriented beam molecules of t-butyl iodide (at a rotational temperature near 15 K) have a higher degree of orientation than the prototype CH3I molecules (JKM state-selected and focused similarly), explainable by the greater importance of the so-called hyperfine disorientation effect for the prolate symmetric top (CH3I) than for the t-C4H9I. For the latter, orientations with photofragment up-down asymmetry ratios as large as a factor of 10 can be achieved, suggesting that t-C4H9I is an excellent candidate reagent for reactive asymmetry studies.

  10. Mighty Molecules

    NSDL National Science Digital Library

    Carlyn Little

    1997-01-01

    In this activity, learners use marshmallows and gum drops to construct seven models of molecules. Learners classify (solid, liquid or gas) and draw diagrams of the molecules. Learners can also create a table showing the chemical formula for each molecule and identify a common use for each chemical. Use this activity to introduce learners to molecules, compounds, and bonds.

  11. Bilateral symmetrical frontoparietal polymicrogyria.

    PubMed

    Sztriha, László; Nork, Michael

    2002-01-01

    A patient with bilateral symmetrical frontoparietal polymicrogyria is reported. Severe developmental delay, mental retardation, spastic tetraplegia, and seizures were the main clinical features. Magnetic resonance imaging revealed bilateral thick cortex with irregular gyri and festoon-like grey-white matter junction in the frontoparietal areas. Bilateral frontoparietal polymicrogyria might represent either a severe form of a spectrum of malformations involving the frontoparietal area or a further variety of the congenital bilateral symmetrical polymicrogyria syndromes in addition to bilateral frontal polymicrogyria, bilateral perisylvian syndrome, and bilateral parasagittal parieto-occipital polymicrogyria. PMID:12374591

  12. Molecule nanoweaver

    DOEpatents

    Gerald, II; Rex E. (Brookfield, IL); Klingler, Robert J. (Glenview, IL); Rathke, Jerome W. (Homer Glen, IL); Diaz, Rocio (Chicago, IL); Vukovic, Lela (Westchester, IL)

    2009-03-10

    A method, apparatus, and system for constructing uniform macroscopic films with tailored geometric assemblies of molecules on the nanometer scale. The method, apparatus, and system include providing starting molecules of selected character, applying one or more force fields to the molecules to cause them to order and condense with NMR spectra and images being used to monitor progress in creating the desired geometrical assembly and functionality of molecules that comprise the films.

  13. Symmetrohedra: Polyhedra from Symmetric

    E-print Network

    Kaplan, Craig S.

    Symmetrohedra: Polyhedra from Symmetric Placement of Regular Polygons Craig S. Kaplan University://www.georgehart.com george@georgehart.com Abstract In the quest for new visually interesting polyhedra with regular faces, we axes of a polyhedral symmetry group. This new technique can be used to generate many existing polyhedra

  14. Yangian symmetric correlators

    NASA Astrophysics Data System (ADS)

    Chicherin, D.; Kirschner, R.

    2013-12-01

    Similarity transformations and eigenvalue relations of monodromy operators composed of Jordan-Schwinger type L matrices are considered and used to define Yangian symmetric correlators of n-dimensional theories. Explicit expressions are obtained and relations are formulated. In this way basic notions of the Quantum inverse scattering method provide a convenient formulation for high symmetry and integrability not only in lower dimensions.

  15. Symmetric Cryptography in Javascript

    Microsoft Academic Search

    Emily Stark; Michael Hamburg; Dan Boneh

    2009-01-01

    We take a systematic approach to developing a symmetric cryptography library in Javascript. We study various strategies for optimizing the code for the Javascript interpreter, and observe that traditional crypto optimization techniques do not apply when implemented in Javascript. We propose a number of optimizations that reduce both running time and code size. Our optimized library is about four times

  16. Top physics at CDF

    SciTech Connect

    Julia Thom

    2004-06-24

    Precision studies of top quark properties are a primary goal of the Run II physics program at the Fermilab Tevatron. Marking the first stages of this program, the CDF collaboration presents recent results on top pair production cross section, single top physics and top mass, using between 109 and 200 pb{sup -1} of Run II data.

  17. Noise-induced dynamic symmetry breaking and stochastic transitions in ABA molecules: II. Symmetricantisymmetric normal mode switching

    E-print Network

    Cao, Jianshu

    Noise-induced dynamic symmetry breaking and stochastic transitions in ABA molecules: II. Symmetric transitions Symmetric-to-antisymmetric normal mode switching Environment induced dephasing Triatomic ABA on the stretching vibrational dynam- ics of symmetric triatomic ABA molecules. In particular, noise

  18. Bilateral and symmetrical tinea mammae

    E-print Network

    Yilmaz, Murat; Kavak, Ayse; Yamaner, Nalan Jale

    2013-01-01

    present a case of bilateral tinea mammae, which has not beenLetter Bilateral and symmetrical tinea mammae Murat Y?lmaz,bilateral symmetrical tinea infection on the breast area. Reported unilateral tinea mammae

  19. Symmetrical reconfiguration of tensegrity structures

    Microsoft Academic Search

    Cornel Sultan; Martin Corless; Robert E. Skelton

    2002-01-01

    In this article we first present a mathematical model which describes the nonlinear dynamics of tensegrity structures. For certain tensegrity structures a particular class of motions, coined symmetrical motions, is defined. The corresponding equations of motion are derived and the conditions under which symmetrical motions occur are established. Reconfiguration procedures through symmetrical motions are proposed and examples are given.

  20. Symmetric modular torsatron

    DOEpatents

    Rome, J.A.; Harris, J.H.

    1984-01-01

    A fusion reactor device is provided in which the magnetic fields for plasma confinement in a toroidal configuration is produced by a plurality of symmetrical modular coils arranged to form a symmetric modular torsatron referred to as a symmotron. Each of the identical modular coils is helically deformed and comprise one field period of the torsatron. Helical segments of each coil are connected by means of toroidally directed windbacks which may also provide part of the vertical field required for positioning the plasma. The stray fields of the windback segments may be compensated by toroidal coils. A variety of magnetic confinement flux surface configurations may be produced by proper modulation of the winding pitch of the helical segments of the coils, as in a conventional torsatron, winding the helix on a noncircular cross section and varying the poloidal and radial location of the windbacks and the compensating toroidal ring coils.

  1. Symmetric iterative interpolation processes

    Microsoft Academic Search

    Gilles Deslauriers; Serge Dubuc

    1989-01-01

    Using a baseb and an even number of knots, we define a symmetric iterative interpolation process. The main properties of this process come from an associated functionF. The basic functional equation forF is thatF(t\\/b)=snF(n\\/b)F(t-n). We prove thatF is a continuous positive definite function. We find almost precisely in which Lipschitz classes derivatives ofF belong. If a functiony is defined only

  2. Marvelous Molecules

    NSDL National Science Digital Library

    1969-12-31

    Presented by the New York Hall of Science, the Marvelous Molecules Web site accompanies its physical museum's exhibit by offering descriptions and additional online activities. The first page "About the Exhibit" shows what is available at the museum and gives interesting facts about molecules. The next page "All About Molecules" explains what a molecule is and gives eight examples (e.g., aspirin and carbon dioxide). The next page called "Marvelous Activities" contains several activities, one of which is the "How Many Molecules Are You?" interactive exercise. Here, users input their weight to see how many molecules their bodies contain and how that compares to other living things. Geared mainly towards kids, the Web site should give all people a fun way to learn.

  3. Interstellar molecules

    NASA Technical Reports Server (NTRS)

    Townes, C. H.

    1976-01-01

    Progress in the discovery and study of interstellar molecules is summarized. The 36 molecular species thus far identified in interstellar space are listed in several groups which include simple hydrides, oxides, and sulfides, various derivatives of ammonia, molecules involving linear carbon chains, cyanides, and molecules related in structure to formaldehyde, alcohols, or ethers. Several free radicals are described, the discovery of molecules in external galaxies is discussed, and possible mechanisms for molecular formation are noted. Methods for examining relative isotopic abundances by measuring molecules in interstellar clouds are outlined, mechanisms for the excitation of interstellar molecules are reviewed, and values are presented for the C-12/C-13 abundance ratio in a number of interstellar clouds. The detection of interstellar masers is discussed along with pumping mechanisms and masing transitions in H2CO, CH, OH, and SiO. The nature of dense interstellar clouds is examined in terms of several simple and complex cloud models, with emphasis on multiple condensation models.

  4. Top Physics at ATLAS

    E-print Network

    Marcello Barisonzi

    2005-08-02

    The Large Hadron Collider LHC is a top quark factory: due to its high design luminosity, LHC will produce about 200 millions of top quarks per year of operation. The large amount of data will allow to study with great precision the properties of the top quark, most notably cross-section, mass and spin. The Top Physics Working Group has been set up at the ATLAS experiment, to evaluate the precision reach of physics measurements in the top sector, and to study the systematic effects of the ATLAS detector on such measurements. This reports give an overview of the main activities of the ATLAS Top Physics Working Group in 2004.

  5. Plane Symmetric, Cylindrically Symmetric and Spherically Symmetric Black Holes Solutions of Einstein Field Equations

    E-print Network

    Farhad Ali

    2014-12-30

    In this paper we present Plane symmetric, Cylindrically Symmetric and Spherically Symmetric Black hole or Vacuum solutions of Einstein Field Equations(EFEs). Some of these solutions are new which we have not seen in the literature. This calculation will help us in understanding the gravitational wave and gravitational wave spacetimes.

  6. Top quark physics

    SciTech Connect

    Ahmadov, A.; Azuelos, G.; Bauer, U.; Belyaev, A.; Berger, E. L.; Sullivan, Z.; Tait, T. M. P.

    2000-03-24

    The top quark, when it was finally discovered at Fermilab in 1995 completed the three-generation structure of the Standard Model (SM) and opened up the new field of top quark physics. Viewed as just another SM quark, the top quark appears to be a rather uninteresting species. Produced predominantly, in hadron-hadron collisions, through strong interactions, it decays rapidly without forming hadrons, and almost exclusively through the single mode t {r_arrow} Wb. The relevant CKM coupling V{sub tb} is already determined by the (three-generation) unitarity of the CKM matrix. Rare decays and CP violation are unmeasurable small in the SM. Yet the top quark is distinguished by its large mass, about 35 times larger than the mass of the next heavy quark, and intriguingly close to the scale of electroweak (EW) symmetry breaking. This unique property raises a number of interesting questions. Is the top quark mass generated by the Higgs mechanism as the SM predicts and is its mass related to the top-Higgs-Yukawa coupling? Or does it play an even more fundamental role in the EW symmetry breaking mechanism? If there are new particles lighter than the top quark, does the top quark decay into them? Could non-SM physics first manifest itself in non-standard couplings of the top quark which show up as anomalies in top quark production and decays? Top quark physics tries to answer these questions. Several properties of the top quark have already been examined at the Tevatron. These include studies of the kinematical properties of top production, the measurements of the top mass, of the top production cross-section, the reconstruction of t{bar t}pairs in the fully hadronic final states, the study of {tau} decays of the top quark, the reconstruction of hadronic decays of the W boson from top decays, the search for flavor changing neutral current decays, the measurement of the W helicity in top decays, and bounds on t{bar t} spin correlations. Most of these measurements are limited by the small sample of top quarks collected at the Tevatron up to now. The LHC is, in comparison, a top factory, producing about 8 million t{bar t}pairs per experiment per year at low luminosity (10 fb{sup {minus}1}/year), and another few million (anti-)tops in EW single (anti-)top quark production. They therefore expect that top quark properties can be examined with significant precision at the LHC. Entirely new measurements can be contemplated on the basis of the large available statistics.

  7. Single Molecules

    NSDL National Science Digital Library

    A new molecular science journal, Single Molecules, from Wiley Interscience, "will provide researchers with a broad overview of current methods and techniques, recent applications and shortcomings of present techniques in the field of single molecules." With temporary free access, the journal's latest issue contains a few full-text articles, with more articles being regularly added. This journal is currently calling for papers.

  8. Top Physics at LHC

    E-print Network

    M. Vander Donckt; for the CMS; ATLAS Collaborations

    2008-05-21

    The Large Hadron Collider (LHC) will provide a huge amount of top-antitop events, making the LHC a top quark factory, producing 1 tt pair per second at a luminosity of 10^33cm-2s-1. A large top quark sample will be available from the start of LHC and will play an important role in commissioning the CMS and ATLAS detectors. An overview of the top quark measurements during the first data-taking period is given.

  9. Top physics at CDF

    SciTech Connect

    Schwarz, Thomas A.; /UC, Davis

    2008-07-01

    Recent results in top physics at CDF presented at the Lake Louise Winter Institute 2008 are discussed, including updates to the top mass, single top search, a search for flavor changing neutral currents in top decay, and W-helicity measurements. Several newer measurements are also presented including the forward-backward asymmetry, the t{bar t} differential cross-section d{sigma}/dM{sub t{bar t}}, and a search for top pair production from massive gluons. Most of the discussed measurements utilize close to 2 fb{sup -1} of data collected at CDF.

  10. Mobius Molecules

    ERIC Educational Resources Information Center

    Eckert, J. M.

    1973-01-01

    Discusses formation of chemical molecules via Mobius strip intermediates, and concludes that many special physics-chemical properties of the fully closed circular form (1) of polyoma DNA are explainable by this topological feature. (CC)

  11. Interstellar Molecules

    ERIC Educational Resources Information Center

    Solomon, Philip M.

    1973-01-01

    Radioastronomy reveals that clouds between the stars, once believed to consist of simple atoms, contain molecules as complex as seven atoms and may be the most massive objects in our Galaxy. (Author/DF)

  12. The Madison Symmetric Torus

    SciTech Connect

    Dexter, R.N.; Kerst, D.W.; Lovell, T.W.; Prager, S.C.; Sprott, J.C.

    1990-03-01

    The Madison Symmetric Torus (MST) is the newest and largest reversed field pinch presently in operation. It incorporates a number of design features that set it apart from other pinches, including the use of the conducting shell as both a vacuum vessel and single-turn toroidal field coil. Specially insulated voltage gaps are exposed to the plasma. Magnetic field errors at these gaps as well as at the various diagnostic and pumping ports are minimized through a variety of techniques. The physics goals of MST include study of the effect of large plasma size on confinement and the investigation, in detail, of RFP turbulence, dynamo and transport. Details of the design and initial operation of the device are presented.

  13. Rotation commensurate echo of asymmetric molecules—Molecular fingerprints in the time domain

    NASA Astrophysics Data System (ADS)

    Chesnokov, E. N.; Kubarev, V. V.; Koshlyakov, P. V.

    2014-12-01

    Using the pulses of terahertz free electron laser and ultra-fast Schottky diode detectors, we observed the coherent transients within a free induction decay of gaseous nitrogen dioxide NO2. The laser excited different sub-bands of rotation spectra of NO2 containing about 50-70 lines. The free induction signal continued more than 30 ns and consisted of many echo-like bursts duration about 0.2 ns. Unlike the similar effect observed previously for linear and symmetric top molecules, the sequence of echo bursts is not periodic. The values for delay of individual echo are stable, and the set of these delays can be considered as a "molecular fingerprint" in the time domain.

  14. Top Physics at CDF

    SciTech Connect

    Moon, Chang-Seong

    2011-06-01

    We present the recent results of top-quark physics using up to 6 fb{sup -1} of p{bar p} collisions at a center of mass energy of {radical}s = 1.96 TeV analyzed by the CDF collaboration. Thanks to this large data sample, precision top quark measurements are now a reality at the Tevatron. Further, several new physics signals could appear in this large dataset. We will present the latest measurements of top quark intrinsic properties as well as direct searches for new physics in the top sector.

  15. {PT}-symmetric optical superlattices

    NASA Astrophysics Data System (ADS)

    Longhi, Stefano

    2014-04-01

    The spectral and localization properties of {PT}-symmetric optical superlattices, either infinitely extended or truncated at one side, are theoretically investigated, and the criteria that ensure a real energy spectrum are derived. The analysis is applied to the case of superlattices describing a complex ( {PT}-symmetric) extension of the Harper Hamiltonian in the rational case.

  16. Leptonic top quark asymmetry predictions at LHCb

    NASA Astrophysics Data System (ADS)

    Gauld, Rhorry

    2015-03-01

    The forward LHCb acceptance offers the possibility of measuring the top-quark pair asymmetry in a kinematic region that does not receive overwhelming dilution from the symmetric gluon-fusion channel. To investigate this possibility, two leptonic final states are identified, and analysis strategies are proposed for each channel with 14 TeV data. Leading fixed-order predictions are then provided for the relevant leptonic asymmetry variables in each channel. If backgrounds can be experimentally constrained, statistically, a nonzero asymmetry is estimated to be observable beyond 5 ? confidence level with the full LHCb 14 TeV data.

  17. 'Escentric' molecules.

    PubMed

    Schön, Geza

    2008-06-01

    Can a fragrance be revolutionary? In this commentary, the creation of two unusual, extravagant fine fragrances, 'escentric01' and 'molecule01', is described. In response to the fantasy components found in release notes of many recent perfume launches, both center around a single real fragrance raw material, the transparent woody aroma chemical 'Iso E Super' (1+2). The perfume 'escentric01' contains 65% of it, accompanied by Trisamber (3), red pepper, lime oil, incense and musks, while 'molecule01' consists exclusively of 'Iso E Super' (1+2). The elegant woody note lives here its own eccentric life--the revolution starts. PMID:18618401

  18. Biological Molecules

    NSDL National Science Digital Library

    Paul Anderson

    2013-03-12

    Paul Anderson describes the four major biological molecules found in living things. He begins with a brief discussion of polymerization. Dehydration synthesis is used to connect monomers into polymers and hydrolysis breaks them down again. The major characteristics of nucleic acids are described as well as there directionality from 3' to 5' end.

  19. Training Top 125

    ERIC Educational Resources Information Center

    Training, 2012

    2012-01-01

    The best learning and development organizations support business initiatives tactically "and" help drive strategic change. Verizon did just that, earning it the No. 1 spot for the first time on the Training Top 125. Verizon and the other 2012 Top 125 winners continued to invest in training, collectively dedicating a mean of 4.52 percent of their…

  20. Training Top 125

    ERIC Educational Resources Information Center

    Training, 2011

    2011-01-01

    Top companies realize how vital training is to their success and continue to invest in it, even in trying times. This article presents "Training" magazine's 11th annual ranking of the top companies with employee-sponsored workforce training and development. First-time No. 1 winner Farmers Insurance puts such a premium on learning that its new…

  1. Oriented molecule beams: Focusing and orientation of t-butyl iodide with analysis by polarized laser photofragmentation

    SciTech Connect

    Xu, Q.; Jung, K.; Bernstein, R.B.

    1988-08-15

    The tert-butyl iodide molecule is readily focused with the electrostatic hexapole, via its first-order Stark effect as a pseudo-symmetric top. The pulsed, seeded supersonic focused beam, characterized by = V/sub th// V/sub 0/ (where theta is the angle between the molecular dipole axis ..mu.. and the electric field E; +- V/sub 0/ the hexapole ''rod voltage,'' and V/sub th/ the so-called threshold voltage), passes into a small homogeneous electric field in which it is oriented. The degree of laboratory orientation achieved is measured using the method of linearly polarized laser-induced photofragmentation (S. R. Gandhi, T. J. Curtiss, and R. B. Bernstein, Phys. Rev. Lett. 59, 2951 (1987)), operating (at three laser wavelengths) on the I(/sup 2/P/sub 3//sub ///sub 2/) and I(/sup 2/P/sub 1//sub ///sub 2/) as well as the t-C/sub 4/H/sub 9/ radical photofragments. The results show that the oriented beam molecules of t-butyl iodide (at a rotational temperature near 15 K) have a higher degree of orientation than the prototype CH/sub 3/I molecules (JKM state-selected and focused similarly), explainable by the greater importance of the so-called hyperfine disorientation effect for the prolate symmetric top (CH/sub 3/I) than for the t-C/sub 4/H/sub 9/I. For the latter, orientations with photofragment up--down asymmetry ratios as large as a factor of 10 can be achieved, suggesting that t-C/sub 4/H/sub 9/I is an excellent candidate reagent for reactive asymmetry studies.

  2. Top physics at CDF

    SciTech Connect

    Hughes, R.E. [Univ. of Rochester, NY (United States)

    1997-01-01

    We report on top physics results using a 100 pb{sup -1} data sample of p{bar p} collisions at {radical}s = 1.8 TeV collected with the Collider Detector at Fermilab (CDF). We have identified top signals in a variety of decay channels, and used these channels to extract a measurement of the top mass and production cross section. A subset of the data (67 pb{sup -1}) is used to determine M{sub top} = 176 {+-} 8(stat) {+-} 10(syst) and {sigma}(tt) = 7.6 {sub -2.0}{sup +2.4} pb. We present studies of the kinematics of t{bar t} events and extract the first direct measurement of V{sub tb}. Finally, we indicate prospects for future study of top physics at the Tevatron.

  3. Small Molecule Inhibitors of Anthrax Lethal Factor Toxin

    PubMed Central

    Williams, John D.; Khan, Atiyya R.; Cardinale, Steven C.; Butler, Michelle M.; Bowlin, Terry L.; Peet, Norton P.

    2014-01-01

    This manuscript describes the preparation of new small molecule inhibitors of Bacillus anthracis lethal factor. Our starting point was the symmetrical, bis-quinolinyl compound 1 (NSC 12155). Optimization of one half of this molecule led to new LF inhibitors that were desymmetrized to afford more drug-like compounds. PMID:24290062

  4. Experimental support for the evolution of symmetric protein architecture from a simple peptide motif.

    PubMed

    Lee, Jihun; Blaber, Michael

    2011-01-01

    The majority of protein architectures exhibit elements of structural symmetry, and "gene duplication and fusion" is the evolutionary mechanism generally hypothesized to be responsible for their emergence from simple peptide motifs. Despite the central importance of the gene duplication and fusion hypothesis, experimental support for a plausible evolutionary pathway for a specific protein architecture has yet to be effectively demonstrated. To address this question, a unique "top-down symmetric deconstruction" strategy was utilized to successfully identify a simple peptide motif capable of recapitulating, via gene duplication and fusion processes, a symmetric protein architecture (the threefold symmetric ?-trefoil fold). The folding properties of intermediary forms in this deconstruction agree precisely with a previously proposed "conserved architecture" model for symmetric protein evolution. Furthermore, a route through foldable sequence-space between the simple peptide motif and extant protein fold is demonstrated. These results provide compelling experimental support for a plausible evolutionary pathway of symmetric protein architecture via gene duplication and fusion processes. PMID:21173271

  5. Experimental support for the evolution of symmetric protein architecture from a simple peptide motif

    PubMed Central

    Lee, Jihun; Blaber, Michael

    2011-01-01

    The majority of protein architectures exhibit elements of structural symmetry, and “gene duplication and fusion” is the evolutionary mechanism generally hypothesized to be responsible for their emergence from simple peptide motifs. Despite the central importance of the gene duplication and fusion hypothesis, experimental support for a plausible evolutionary pathway for a specific protein architecture has yet to be effectively demonstrated. To address this question, a unique “top-down symmetric deconstruction” strategy was utilized to successfully identify a simple peptide motif capable of recapitulating, via gene duplication and fusion processes, a symmetric protein architecture (the threefold symmetric ?-trefoil fold). The folding properties of intermediary forms in this deconstruction agree precisely with a previously proposed “conserved architecture” model for symmetric protein evolution. Furthermore, a route through foldable sequence-space between the simple peptide motif and extant protein fold is demonstrated. These results provide compelling experimental support for a plausible evolutionary pathway of symmetric protein architecture via gene duplication and fusion processes. PMID:21173271

  6. Experimental Support for the Evolution of Symmetric Protein Architecture from a Simple Peptide Motif

    SciTech Connect

    J Lee; M Blaber

    2011-12-31

    The majority of protein architectures exhibit elements of structural symmetry, and 'gene duplication and fusion' is the evolutionary mechanism generally hypothesized to be responsible for their emergence from simple peptide motifs. Despite the central importance of the gene duplication and fusion hypothesis, experimental support for a plausible evolutionary pathway for a specific protein architecture has yet to be effectively demonstrated. To address this question, a unique 'top-down symmetric deconstruction' strategy was utilized to successfully identify a simple peptide motif capable of recapitulating, via gene duplication and fusion processes, a symmetric protein architecture (the threefold symmetric {beta}-trefoil fold). The folding properties of intermediary forms in this deconstruction agree precisely with a previously proposed 'conserved architecture' model for symmetric protein evolution. Furthermore, a route through foldable sequence-space between the simple peptide motif and extant protein fold is demonstrated. These results provide compelling experimental support for a plausible evolutionary pathway of symmetric protein architecture via gene duplication and fusion processes.

  7. Achromatic axially symmetric wave plate.

    PubMed

    Wakayama, Toshitaka; Komaki, Kazuki; Otani, Yukitoshi; Yoshizawa, Toru

    2012-12-31

    An achromatic axially symmetric wave plate (AAS-WP) is proposed that is based on Fresnel reflections. The wave plate does not introduce spatial dispersion. It provides retardation in the wavelength domain with an axially symmetric azimuthal angle. The optical configuration, a numerical simulation, and the optical properties of the AAS-WP are described. It is composed of PMMA. A pair of them is manufactured on a lathe. In the numerical simulation, the achromatic angle is estimated and is used to design the devices. They generate an axially symmetric polarized beam. The birefringence distribution is measured in order to evaluate the AAS-WPs. PMID:23388751

  8. Top Quark Properties

    SciTech Connect

    Peters, Yvonne

    2011-12-01

    Since its discovery in 1995 by the CDF and D0 collaborations at the Fermilab Tevatron collider, the top quark has undergone intensive studies. Besides the Tevatron experiments, with the start of the LHC in 2010 a top quark factory started its operation. It is now possible to measure top quark properties simultaneously at four different experiments, namely ATLAS and CMS at LHC and CDF and D0 at Tevatron. Having collected thousands of top quarks each, several top quark properties have been measured precisely, while others are being measured for the first time. In this article, recent measurements of top quark properties from ATLAS, CDF, CMS and D0 are presented, using up to 5.4 fb{sup -1} of integrated luminosity at the Tevatron and 1.1 fb{sup -1} at the LHC. In particular, measurements of the top quark mass, mass difference, foward backward charge asymmetry, t{bar t} spin correlations, the ratio of branching fractions, W helicity, anomalous couplings, color flow and the search for flavor changing neutral currents are discussed.

  9. Moving Molecules!

    NSDL National Science Digital Library

    2014-06-24

    In this activity about molecular diffusion (located on page 2 of the PDF), learners will make predictions and move molecules of iodine through a seemingly solid plastic sandwich bag. The process of diffusion will be visually indicated by a color change when the iodine reacts with starch inside the bag. Information in the resource explains how this activity relates to nanoparticles and research. Related to linked video, DragonflyTV Nano: Nanosilver.

  10. Top quark production

    E-print Network

    Mara Senghi Soares

    2014-09-25

    We review the current status of the cross sections measurement of the top-quark at the LHC and at the Tevatron. Total production cross sections, studies using single top quark events and differential $\\rm{t}\\bar{\\rm t}$ cross sections are discussed. The associated production of top quark pairs with photons, Z and W bosons, including $\\rm{t}\\bar{\\rm t}$Z and $\\rm{t}\\bar{\\rm t}$W measurements shown for the first time at LHCP2014, are presented.

  11. Computing Rovibrational Levels of Polyatomic Molecules with Curvilinear Internal Vibrational Coordinates and AN Eckart Frame

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Gang; Carrington, Tucker, Jr.

    2013-06-01

    We present a new procedure for computing a rovibrational spectrum of a polyatomic molecule. %and apply it to methane. The Schrödinger equation is solved, numerically exactly, by using a nested contracted basis. Rovibrational wavefunctions are computed in a | v > | JKM > basis, where | v > is a vibrational wavefunction and | JKM > is a symmetric top wavefunction. In turn, the | v > are obtained by solving a vibrational Schrödinger equation with basis functions that are products of contracted bend and stretch functions. At all stages of the calculation we exploit parity symmetry. The calculations are done in internal coordinates that facilitate the treatment of large amplitude motion. An Eckart molecule-fixed frame is used by numerically computing coefficients of the kinetic energy operator. The method is significantly more efficient than the previous method which uses a molecule-fixed frame attached to two vectors and vibrational basis functions that depend on K. The efficacy of the method is demonstrated by calculating a large number of converged J=10 methane rovibrational levels in the Tetradecad polyad (vibrational energies in the range 5100 - 6100 cm^{-1}). No previous calculation of rovibrational levels of methane includes as many levels as we report in this paper. footnote{X.-G. Wang and T. Carrington, Jr., J. Chem. Phys. {138}, 000000 (2013).} A. B. McCoy, D. C. Burleigh, and E. L. Sibert, J. Chem. Phys. {95}, 7449 (1991). X.-G. Wang and T. Carrington, Jr., J. Chem. Phys. {121}, 2937 (2004).

  12. Top quark mass measurements

    SciTech Connect

    Hill, Christopher S.; /UC, Santa Barbara

    2004-12-01

    The top quark, with its extraordinarily large mass (nearly that of a gold atom), plays a significant role in the phenomenology of EWSB in the Standard Model. In particular, the top quark mass when combined with the W mass constrains the mass of the as yet unobserved Higgs boson. Thus, a precise determination of the mass of the top quark is a principal goal of the CDF and D0 experiments. With the data collected thus far in Runs 1 and 2 of the Tevatron, CDF and D0 have measured the top quark mass in both the lepton+jets and dilepton decay channels using a variety of complementary experimental techniques. The author presents an overview of the most recent of the measurements.

  13. Dare we teach tops?

    NASA Astrophysics Data System (ADS)

    Featonby, David

    2010-07-01

    Tops are mentioned in classical literature and references are even found in the ancient world. For many children a top is one of the first mechanical toys that they play with by themselves, yet a full appreciation of their motion is rare. My hope is that this article will stimulate the reader's interest in tops, will help with the first stages of understanding, and will provide inspiration for looking into the subject further. As a result of this, teachers will be happy and have the confidence to discuss these wonderful toys with their pupils. The article discusses tops and spinning objects of various types, and relates them to some of the physical principles that they demonstrate.

  14. Single molecule spectroscopy of tetrahedral oligophenylenevinylene molecules

    E-print Network

    Buratto, Steve

    Single molecule spectroscopy of tetrahedral oligophenylenevinylene molecules Melissa A. Summers form 17 July 2002 Abstract We probe the fluorescence from single molecules of a new class of tetrahedral oligo(phenylenevinylene) (OPV) molecules. Our results show that the tetrahedral molecules contain

  15. Building Molecules

    NSDL National Science Digital Library

    Rensselaer Polytechnic Institute

    2005-01-01

    This online interactive has three activities in the NanoLab (press the upper right button): Build, Zoom, and Transform. In Build, learners build increasingly complex molecules out of carbon, oxygen, and hydrogen, and is useful for connecting subscripts and the number of atoms, and for introducing 3D molecular structures which are automatically built. Zoom is a "powers of 10" zoom-in ranging from 10,000 kilometers to 1 nanometer. Transform is a simulation of water changing phase from solid to liquid to gas. Through exploration of the site learners form a better understanding of the composition of matter.

  16. Vibration frequencies for searches of free triatomic molecules in interstellar space

    NASA Astrophysics Data System (ADS)

    Hefferlin, R.; Barrow, J.

    2014-11-01

    More and more cold interstellar molecules are being discovered, the majority of them being organic. Perhaps it is time to consider the numerous small molecules that also await observation. We report progress in tabulating symmetric-stretch vibration frequencies for neutral main-group ground-state triatomic molecules, formed from period-2 atoms, which are not yet studied.

  17. Phi-symmetric effect algebras

    NASA Astrophysics Data System (ADS)

    Bennett, M. K.; Foulis, D. J.

    1995-12-01

    The notion of a Sasaki projection on an orthomodular lattice is generalized to a mapping ?: E × E ? E, where E is an effect algebra. If E is lattice ordered and ? is symmetric, then E is called a ?-symmetric effect algebra. This paper launches a study of such effect algebras. In particular, it is shown that every interval effect algebra with a lattice-ordered ambient group is ?-symmetric, and its group is the one constructed by Ravindran in his proof that every effect algebra that has the Riesz decomposition property is an interval algebra. It is shown that the doubling construction introduced in the paper is connected to the conditional event algebras of Goodman, Nguyen, and Walker.

  18. Top-ophilia

    SciTech Connect

    Quigg, Chris; /Fermilab

    2008-01-01

    Almost from the moment in June 1977 when the discovery of the Upsilon resonance revealed the existence of what we now call the bottom quark, physicists began searching for its partner. Through the years, as we established the electric charge and weak isospin of the b-quark, and detected the virtual influence of its mate, it became clear that the top quark must exist. Exactly at what mass, we couldn't say, but we knew just how top events would look. We also knew that top events would be rare--if the Tevatron could make them at all--and that picking out the events would pose a real challenge for the experimenters and their detectors.

  19. Top quark physics: Future measurements

    SciTech Connect

    Frey, R. [Univ. of Oregon, Eugene, OR (United States). Dept. of Physics; Vejcik, S. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Physics; Berger, E.L. [Argonne National Lab., IL (United States)] [and others

    1997-04-04

    The authors discuss the study of the top quark at future experiments and machines. Top`s large mass makes it a unique probe of physics at the natural electroweak scale. They emphasize measurements of the top quark`s mass, width, and couplings, as well as searches for rare or nonstandard decays, and discuss the complementary roles played by hadron and lepton colliders.

  20. Interpolation via symmetric exponential functions

    NASA Astrophysics Data System (ADS)

    Bezubik, Agata; Pošta, Severin

    2013-11-01

    Complex valued functions on the Euclidean space Bbb Rn, symmetric or antisymmetric with respect to the permutation group Sn, are often dealt with in various branches of physics, such as quantum theory or theory of integrable systems. One often needs to approximate such functions with series consisting of various special functions which satisfy nice properties. Questions of uniform convergence of such approximations are crucial for applications. In this article a family of special functions called the symmetric exponential functions are used for such approximation and the uniform convergence of their sums is considered.

  1. Top quark production at CDF

    SciTech Connect

    Moed, Shulamit; /Harvard U.

    2010-01-01

    The large data samples of top quark candidate events collected at the Tevatron CDF II experiment allow for a variety of measurements to analyze the production of the top quark. This article discusses recent results of top quark production at CDF presented at the SUSY09 conference, including updates to the top pair production cross section, forward-backward asymmetry in t{bar t} production, single top search, search for top resonances and a search for heavy top. The discussed measurements utilize up to 3.2 fb{sup -1} of integrated luminosity collected at CDF.

  2. Optical analogues of spherically symmetric black hole spacetimes

    NASA Astrophysics Data System (ADS)

    Hegde, S. S.; Vishveshwara, C. V.

    2014-03-01

    We have given an analytical formalism for developing optical analogues of spherically symmetric black hole spacetimes, and demonstrated the exact similarity between the electromagnetic wave equations in an inhomogeneous medium in flat spacetime and in a general relativistic curved spacetime. The permittivity and permeability of the inhomogeneous optical medium act as the metric components of an effective optical spacetime. Manifest properties of black holes, like curved trajectories of light rays and quasi-normal modes follow directly from our formalism. It is also applied to the specific case of Schwarzschild spacetime. The formalism would facilitate table-top experiments to investigate black hole phenomena.

  3. Mind Molecules

    PubMed Central

    Snyder, Solomon H.

    2011-01-01

    Scientific styles vary tremendously. For me, research is largely about the unfettered pursuit of novel ideas and experiments that can test multiple ideas in a day, not a year, an approach that I learned from my mentor Julius “Julie” Axelrod. This focus on creative conceptualizations has been my métier since working in the summers during medical school at the National Institutes of Health, during my two years in the Axelrod laboratory, and throughout my forty-five years at Johns Hopkins University School of Medicine. Equally important has been the “high” that emerges from brainstorming with my students. Nothing can compare with the eureka moments when, together, we sense new insights and, better yet, when high-risk, high-payoff experiments succeed. Although I have studied many different questions over the years, a common theme emerges: simple biochemical approaches to understanding molecular messengers, usually small molecules. Equally important has been identifying, purifying, and cloning the messengers' relevant biosynthetic, degradative, or target proteins, at all times seeking potential therapeutic relevance in the form of drugs. In the interests of brevity, this Reflections article is highly selective, and, with a few exceptions, literature citations are only of findings of our laboratory that illustrate notable themes. PMID:21543333

  4. Ten Top Tech Trends

    ERIC Educational Resources Information Center

    McLester, Susan

    2008-01-01

    In this article, the author discusses the major technical issues, products, and practices of the day. The top ten tech trends are listed and discussed. These include: (1) data mining; (2) cyberbullying; (3) 21st century skills; (4) digital content; (5) learning at leisure; (6) personal responders; (7) mobile tools; (8) bandwidth; (9) open-source…

  5. Top Hispanic Degree Producers

    ERIC Educational Resources Information Center

    Diverse: Issues in Higher Education, 2012

    2012-01-01

    This article presents a list of the top 100 producers of associate, bachelor's and graduate degrees awarded to minority students based on research conducted by Dr. Victor M.H. Borden, professor of educational leadership and policy students at the Indiana University Bloomington. For the year 2012, the listings focus on Hispanic students. Data for…

  6. Secure Symmetrical Multilevel Diversity Coding

    E-print Network

    Li, Shuo

    2012-07-16

    Secure symmetrical multilevel diversity coding (S-SMDC) is a source coding problem, where a total of L - N discrete memoryless sources (S1,...,S_L-N) are to be encoded by a total of L encoders. This thesis considers a natural generalization of SMDC...

  7. Synthesis of a symmetrical dithiirane

    SciTech Connect

    Allakverdiev, M.A.; Farzaliev, V.M.; Mamedov, C.I.

    1986-04-01

    The reaction of p-xylene with epichlorohydrin in the presence of aluminum chloride gave 1,4-dimethyl-2,5-bis(1-chloro-2-hydroxypropyl) benzene, which serves as the starting compound for the synthesis of the corresponding symmetrical dithiirane.

  8. Simulation of Symmetrical Induction Machinery

    Microsoft Academic Search

    P. C. Krause; C. H. Thomas

    1965-01-01

    The effectiveness of an analog computer in studying the performance of induction machinery is demonstrated with computer results which show the dynamic behavior of 2-phase and 3-phase machines during balanced and unbalanced operation. The computer simulation for these various modes of operation is conveniently obtained from the equations which describe the symmetrical induction machine in an arbitrary reference frame. Of

  9. Top-Down Processing Top versus Bottom Word Superiority Effect

    E-print Network

    Coulson, Seana

    1 Top-Down Processing Top versus Bottom Word Superiority Effect WORK K C/K C/K Sentence Superiority · Pre-attentional, parallel processing of features · Serial process of feature integration · Focused

  10. Measurement of cosmic ray energy spectrum with IceTop

    NASA Astrophysics Data System (ADS)

    Ruzybayev, Bakhtiyar

    The main focus of this dissertation is the measurement of the all particle cosmic ray energy spectra with the IceTop air shower array in the energy range from 1 petaelectronvolt (PeV) up to 1 exaelectronvolt (EeV). The IceTop air shower array is the surface component of the IceCube South Pole Neutrino Observatory. The analysis was performed using only information from IceTop. The data used in this work were taken during eleven months from June 1, 2010 to May15, 2011. During that period the IceTop array consisted of 73 stations compared to 81 in its final configuration. The array forms a nearly symmetrical hexagon. In the first few chapters I will give a brief review of cosmic ray physics, describe some other experiments in this field and introduce the IceTop detector itself. The analysis part of the dissertation consists of two studies. In the first study, low energy (below knee), small showers were analyzed with the goal of lowering IceTop detector threshold to make a connection with direct measurements. In the second part I will present results for the showers with energies higher than 1PeV.

  11. Top500 Supercomputer Sites

    NSDL National Science Digital Library

    2002-01-01

    Twice a year, the Top500 Project releases a list of the 500 sites with the most powerful supercomputers. The purpose of the list is "to provide a reliable basis for tracking and detecting trends in high-performance computing." The latest version was unveiled in June, and this site examines some of the most important developments and newcomers to the list. Most important is the recently constructed Earth Simulator in Japan, which was rated almost five times more powerful than second place. Additional analysis shows other information about the direction of supercomputing, such as performance projections and country shares of the top 500. A detailed report on recent supercomputers, looking at different architectural classes, can be also found on the site.

  12. A DNA primer associated with banana bunchy top virus

    Microsoft Academic Search

    Gregory J. Hafner; Robert M. Harding; James L. Dale

    Banana bunchy top virus (BBTV) genomic ssDNA is capable of complementary strand synthesis in vitro without the addition of exogenous primers. We have demonstrated that the self-priming of BBTV can be attributed to a population of endogenous primers which are bound to the genomic DNA within the virions. The primer molecules appeared to be composed entirely of DNA and are

  13. DNA Security using Symmetric and Asymmetric Cryptography

    Microsoft Academic Search

    Radu Terec; MirceaFlorin Vaida; Lenuta Alboaie; Ligia Chiorean

    This paper presents alternative security methods based on DNA. From the available alternative security methods, symmetric DNA algorithms were developed and implemented. The first symmetric DNA algorithm was implemented in the Java language, while the second DNA algorithm was implemented in BioJava and MatLab. Comparisons have been made between the performances of different standard symmetrical algorithms and the DNA proposed

  14. DNA Security using Symmetric and Asymmetric Cryptography

    Microsoft Academic Search

    L. Alboaie L. Chiorean M. Vaida Radu Terec

    2011-01-01

    This paper presents alternative security methods based on DNA. From the available alternative security methods, symmetric DNA algorithms were developed and implemented. The first symmetric DNA algorithm was implemented in the Java language, while the second DNA algorithm was implemented in BioJava and MatLab. Comparisons have been made between the performances of different standard symmetrical algorithms and the DNA proposed

  15. Perturbation theory of PT-symmetric Hamiltonians

    E-print Network

    E. Caliceti; F. Cannata; S. Graffi

    2006-07-19

    In the framework of perturbation theory the reality of the perturbed eigenvalues of a class of $\\PT$symmetric Hamiltonians is proved using stability techniques. We apply this method to $\\PT$symmetric unperturbed Hamiltonians perturbed by $\\PT$symmetric additional interactions.

  16. Single molecule junctions, where a molecule with its perfect chemical reproducibility and versatility is the active part of an electronic device,

    E-print Network

    Schubart, Christoph

    Single molecule junctions, where a molecule with its perfect chemical reproducibility characteristics of nanojunctions both in the single electron transistor and the scanning tunneling microscopy (STM of modern electronics. Quantum dot molecules (QDM) represent a top-down one. A QDM is composed of two

  17. PT-Symmetric Phonon Laser

    E-print Network

    H. Jing; Sahin K. Ozdemir; Xin-You Lv; Jing Zhang; Lan Yang; Franco Nori

    2014-08-01

    By exploiting recent developments associated with coupled microcavities, we introduce the concept of PT-symmetric phonon laser with balanced gain and loss. This is accomplished by introducing gain to one of the microcavities such that it balances the passive loss of the other. In the vicinity of the gain-loss balance, a strong nonlinear relation emerges between the intracavity photon intensity and the input power. This then leads to a giant enhancement of both optical pressure and mechanical gain, resulting in a highly efficient phonon-lasing action. These results provide a promising approach for manipulating optomechanical systems through PT-symmetric concepts. Potential applications range from enhancing mechanical cooling to designing phonon-laser amplifiers.

  18. Symmetrization, quantum images and measurement

    E-print Network

    Fariel Shafee

    2005-07-11

    We argue that symmetrization of an incoming microstate with similar states in a sea of microstates contained in a macroscopic detector can produce an effective image, which does not contradict the no-cloning theorem, and such a combinatorial set can then be used with first passage random walk interactions suggested in an earlier work to give the right quantum mechanical weight for measured eigenvalues.

  19. Viscosity in spherically symmetric accretion

    E-print Network

    Arnab K. Ray

    2004-09-27

    The influence of viscosity on the flow behaviour in spherically symmetric accretion, has been studied here. The governing equation chosen has been the Navier-Stokes equation. It has been found that at least for the transonic solution, viscosity acts as a mechanism that detracts from the effectiveness of gravity. This has been conjectured to set up a limiting scale of length for gravity to bring about accretion, and the physical interpretation of such a length-scale has been compared with the conventional understanding of the so-called "accretion radius" for spherically symmetric accretion. For a perturbative presence of viscosity, it has also been pointed out that the critical points for inflows and outflows are not identical, which is a consequence of the fact that under the Navier-Stokes prescription, there is a breakdown of the invariance of the stationary inflow and outflow solutions -- an invariance that holds good under inviscid conditions. For inflows, the critical point gets shifted deeper within the gravitational potential well. Finally, a linear stability analysis of the stationary inflow solutions, under the influence of a perturbation that is in the nature of a standing wave, has indicated that the presence of viscosity induces greater stability in the system, than has been seen for the case of inviscid spherically symmetric inflows.

  20. Top Physics at the LHC

    E-print Network

    P. de Jong

    2009-02-27

    The LHC will be a top quark factory. In this note, the central role of the top quark for LHC physics will be discussed, and an overview will be given of the studies of top quark properties in preparation, with an emphasis on the systematic uncertainties that will dominate most measurements.

  1. Top Physics at the LHC

    E-print Network

    Christian Weiser

    2005-06-10

    Top quark physics will be a prominent topic in Standard Model physics at the LHC. The enormous amount of top quarks expected to be produced will allow to perform a wide range of precision measurements. An overview of the planned top physics programme of the ATLAS and CMS experiments at the LHC is given.

  2. Top quark physics: Future Measurements

    SciTech Connect

    Frey, Raymond; Gerdes, David; Jaros, John; Vejcik, Steve; Berger, Edmond L.; Chivukula, R. Sekhar; Cuypers, Frank; Drell, Persis S.; Fero, Michael; Hadley, Nicholas; Han, Tao; Heinson, Ann P.; Knuteson, Bruce; Larios, Francisco; Miettinen, Hannu; Orr, Lynne H.; Peskin, Michael E.; Rizzo, Thomas; Sarid, Uri; Schmidt, Carl; Stelzer, Tim; Sullivan, Zack

    1996-12-31

    We discuss the study of the top quark at future experiments and machines. Top's large mass makes it a unique probe of physics at the natural electroweak scale. We emphasize measurements of the top quark's mass, width, and couplings, as well as searches for rare or nonstandard decays, and discuss the complementary roles played by hadron and lepton colliders.

  3. Top physics results at CDF

    SciTech Connect

    Vickey, Trevor; /Illinois U., Urbana

    2005-05-01

    The most recent results on top quark physics at CDF are reported. Measurements of cross-section and mass are presented, and the status of single top quark production searches are discussed. The results obtained from probing various top quark properties are also presented.

  4. Curly Top Disease of Tomato

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Curly top disease, caused by viruses in the genus, Curtovirus, has impacted western US agriculture for over a century; and is a significant threat to tomato production. The two most abundant curtovirus species today are Beet severe curly top virus (BSCTV) and Beet mild curly top virus (BMCTV) but ot...

  5. Efficient All Top-k Computation A unified solution for all top-k, reverse top-k and top-m influential queries

    E-print Network

    Efficient All Top-k Computation A unified solution for all top-k, reverse top-k and top problem is to com- pute the top ranked objects for all functions. Evaluation of multiple top-k queries engines and produc- t recommendation systems). The simple solution of evaluating the top-k queries one

  6. Broadening and shifting of the methanol 119 {mu}m gain line of linear and circular polarization by collision with chiral molecules

    SciTech Connect

    J.S. Bakos; G. Djotyan; Zsuzsa Soerlei; J. Szigeti; D. K. Mansfield; J. Sarkozi

    2000-06-21

    Evidence of circular dichroism has been observed in the spectral properties of a gas of left-right symmetric molecules. This dichroism comes about as the result of collisions of the symmetric molecules with left-right asymmetric molecules introduced as a buffer gas. In this sense, the dichroism can be said to have been transferred from the chiral buffer molecules to the symmetric, non-chiral molecules of the background vapor. This transferred dichroism appears as broadening in the gain line of the symmetric molecule which is asymmetric with respect to the right or left handedness of a circularly polarized probe. The broadening of the 119 {mu}m line of the methanol molecule was observed using infrared-far infrared double resonance spectroscopy.

  7. Constraining the charged Higgs mass in the left--right symmetric model from $b \\to s ?$

    E-print Network

    Gautam Bhattacharyya; Amitava Raychaudhuri

    1995-11-28

    In the context of the left--right symmetric model, the decay $b \\rightarrow s \\gamma$ receives contributions from the gauge interactions mediated mainly by the $W_L$, through $W_L$--$W_R$ mixing and also from the Yukawa interactions of the charged and the neutral (flavour-changing) scalars (the latter type of Yukawa interaction has been overlooked in the previous literature). Following the recent CLEO measurement of the inclusive $b \\rightarrow s \\gamma$ process and the measurement of the top-quark mass by the CDF and D0 collaborations, the parameter space of the left--right symmetric model is more squeezed than before.

  8. Modeling Symmetric Macromolecular Structures in Rosetta3

    PubMed Central

    DiMaio, Frank; Leaver-Fay, Andrew; Bradley, Phil; Baker, David; André, Ingemar

    2011-01-01

    Symmetric protein assemblies play important roles in many biochemical processes. However, the large size of such systems is challenging for traditional structure modeling methods. This paper describes the implementation of a general framework for modeling arbitrary symmetric systems in Rosetta3. We describe the various types of symmetries relevant to the study of protein structure that may be modeled using Rosetta's symmetric framework. We then describe how this symmetric framework is efficiently implemented within Rosetta, which restricts the conformational search space by sampling only symmetric degrees of freedom, and explicitly simulates only a subset of the interacting monomers. Finally, we describe structure prediction and design applications that utilize the Rosetta3 symmetric modeling capabilities, and provide a guide to running simulations on symmetric systems. PMID:21731614

  9. Top-Down Mass Spectrometry: Recent Developments, Applications and Perspectives

    PubMed Central

    Cui, Weidong; Rohrs, Henry W.; Gross, Michael L.

    2012-01-01

    Top-down mass spectrometry is an emerging approach for the analysis of intact proteins. The term was coined as a contrast with the better-established, bottom-up strategy for analysis of peptide fragments derived from digestion, either enzymatically or chemically, of intact proteins. Although the term top-down originates from proteomics, it can also be applied to mass spectrometric analysis of intact large biomolecules that are constituents of protein assemblies or complexes. Traditionally, mass spectrometry has usually started with intact molecules, and in this regard, top-down approaches reflect the spirit of mass spectrometry. This article provides an overview of the methodologies in top-down mass spectrometry and then reviews applications covering protein posttranslational modifications, protein biophysics, DNAs/RNAs, and protein assemblies. Finally, challenges and future directions are discussed. PMID:21826297

  10. Top quark physics at CDF

    SciTech Connect

    Potamianos, Karolos

    2011-12-01

    We present the recent results of top-quark physics using up to 6 fb{sup -1} of p{bar p} collisions analyzed by the CDF collaboration. The large number of top quark events analyzed, of the order of several thousands, allows stringent checks of the standard model predictions. Also, the top quark is widely believed to be a window to new physics. We present the latest measurements of top quark intrinsic properties as well as direct searches for new physics in the top sector.

  11. Computing Z_top

    E-print Network

    Amir-Kian Kashani-Poor

    2014-08-06

    This is the text of my habilitation thesis defended at the \\'Ecole Normale Sup\\'erieure. The topological string presents an arena in which many features of string theory proper, such as the interplay between worldsheet and target space descriptions or open-closed duality, can be distilled into computational techniques which yield results beyond perturbation theory. In this thesis, I will summarize my research activity in this area. The presentation is organized around computations of the topological string partition function Z_top based on various perspectives on the topological string.

  12. Noise-Induced Dynamic Symmetry Breaking and Stochastic Transitions in ABA Molecules: I. Classification of Vibrational Modes

    E-print Network

    Cao, Jianshu

    Noise-Induced Dynamic Symmetry Breaking and Stochastic Transitions in ABA Molecules: I dynamics of a symmetric triatomic ABA molecule is extensively studied in a series of three papers. The momentum-dependent rotor model is used to describe the dynamical behavior of an ABA molecule with a single

  13. Top quark mass measurements

    SciTech Connect

    L. Cerrito

    2004-07-16

    Preliminary results on the measurement of the top quark mass at the Tevatron Collider are presented. In the dilepton decay channel, the CDF Collaboration measures m{sub t} = 175.0{sub -16.9}{sup +17.4}(stat.){+-}8.4(syst.) GeV/c{sup 2}, using a sample of {approx} 126 pb{sup -1} of proton-antiproton collision data at {radical}s = 1.96 TeV (Run II). In the lepton plus jets channel, the CDF Collaboration measures 177.5{sub -9.4}{sup +12.7}(stat.) {+-} 7.1(syst.) GeV/c{sup 2}, using a sample of {approx} 102 pb{sup -1} at {radical}s = 1.96 TeV. The D0 Collaboration has newly applied a likelihood technique to improve the analysis of {approx} 125 pb{sup -1} of proton-antiproton collisions at {radical}s = 1.8 TeV (Run I), with the result: m{sub t} = 180.1 {+-} 3.6(stat.) {+-}3.9(syst.) GeV/c{sup 2}. The latter is combined with all the measurements based on the data collected in Run I to yield the most recent and comprehensive experimental determination of the top quark mass: m{sub t} = 178.0 {+-} 2.7(stat.) {+-} 3.3(syst.) GeV/c{sup 2}.

  14. Water Molecule Residence Times

    NSDL National Science Digital Library

    Sill - Earth Systems Science

    2010-11-16

    How long will a molecule of Water stay in a particular reservoir? What is the average time a molecule of Water will stay in an ocean? What is the average time a molecule of water will stay in a river? A lake? As groundwater? A glacier? How long will a water vapor molecule stay suspended in the atmosphere? Why is the residence ...

  15. Molecule of the Month

    NSDL National Science Digital Library

    From the University of Bristol's School of Chemistry, this site features a new molecule each month. For example, the molecule for April is Melatonin. Each molecule comes with a link to a Webpage from a university or commercial site containing further information. (Links may require Chime, VRML, or Java.) Contributors may submit molecule pages to be considered in future months. Monthly molecules date back to January 1996.

  16. Top physics results from CDF

    SciTech Connect

    Gomez, Gervasio; /Cantabria Inst. of Phys.

    2005-05-01

    The top quark is by far the most massive fundamental particle observed so far, and the study of its properties is interesting for several reasons ranging from its possible special role in electroweak symmetry breaking to its sensitivity to physics beyond the Standard Model. They present recent top physics results from CDF based on 160-320 pb{sup -1} of p{bar p} collision data at {radical}s = 1.96 TeV. The t{bar t} cross section and the top mass have been measured in different decay channels and using different methods. they have searched for evidence of single top production, setting upper limits on its production rate. Other results shown in this conference include studies of the polarization of W bosons from top decays, a search for charged Higgs decaying from top, and a search for additional heavy t' quarks.

  17. Single Top production at LHC

    E-print Network

    M. Mohammadi Najafabadi

    2006-05-15

    The Production of single top quarks at LHC provides an ideal framework to investigate the properties of electroweak interaction, in particular of the {\\it tWb} coupling. Moreover, single top is a powerful mean to identify physics beyond the standard model. All three different production mechanisms of single top are expected to be observed at LHC. Recent studies from ATLAS and CMS are presented.

  18. Frustration in bilayers and topologies of liquid crystals of amphiphilic molecules

    E-print Network

    Paris-Sud XI, Université de

    683 Frustration in bilayers and topologies of liquid crystals of amphiphilic molecules J. F. Sadoc dicembre 1985) Résumé. - Les molécules amphiphiles construisent des films fluides symétriques, bicouches. - Amphiphilic molecules are well-known for their ability to build symmetric fluid films, or bilayers, most often

  19. Origin of symmetric PMNS and CKM matrices

    NASA Astrophysics Data System (ADS)

    Rodejohann, Werner; Xu, Xun-Jie

    2015-03-01

    The Pontecorvo-Maki-Nakagawa-Sakata and Cabibbo-Kobayashi-Maskawa matrices are phenomenologically close to symmetric, and a symmetric form could be used as zeroth-order approximation for both matrices. We study the possible theoretical origin of this feature in flavor symmetry models. We identify necessary geometric properties of discrete flavor symmetry groups that can lead to symmetric mixing matrices. Those properties are actually very common in discrete groups such as A4 , S4 , or ? (96 ) . As an application of our theorem, we generate a symmetric lepton mixing scheme with ?12=?23=36.21 ° ; ?13=12.20 ° , and ? =0 , realized with the group ? (96 ) .

  20. Modern Symmetric Cryptography methodologies and its applications

    E-print Network

    Malayeri, Amin Daneshmand

    2009-01-01

    Nowadays, using cryptographic systems play an effective role in security and safety technologies. One of the most applied kind of cryptography is Symmetric Cryptography and its applications. New aspects of symmetric Cryptography methodologies and applications has been presented by this paper. Security-based networks and some complex technologies such as RFID and parallel security settings has been intro-duced by using Symmetric Cryptography is the main base of discussion in this paper. Designing an unique protocol for Symmetric Cryptography in security networks elements is our focus. Reviewing benefits of using these methodologies has been pre-sented and discussed in this paper.

  1. Boosted top: experimental tools overview

    E-print Network

    Usai, Emanuele

    2015-01-01

    An overview of tools and methods for the reconstruction of high-boost top quark decays at the LHC is given in this report. The focus is on hadronic decays, in particular an overview of the current status of top quark taggers in physics analyses is presented. The most widely used jet substructure techniques, normally used in combination with top quark taggers, are reviewed. Special techniques to treat pileup in large cone jets are described, along with a comparison of the performance of several boosted top quark reconstruction techniques.

  2. Boosted top: experimental tools overview

    E-print Network

    Emanuele Usai; for the ATLAS; CMS Collaborations

    2015-01-05

    An overview of tools and methods for the reconstruction of high-boost top quark decays at the LHC is given in this report. The focus is on hadronic decays, in particular an overview of the current status of top quark taggers in physics analyses is presented. The most widely used jet substructure techniques, normally used in combination with top quark taggers, are reviewed. Special techniques to treat pileup in large cone jets are described, along with a comparison of the performance of several boosted top quark reconstruction techniques.

  3. A Minimally Symmetric Higgs Boson

    E-print Network

    Ian Low

    2014-12-05

    Models addressing the naturalness of a light Higgs boson typically employ symmetries, either bosonic or fermionic, to stabilize the Higgs mass. We consider a setup with the minimal amount of symmetries: four shift symmetries acting on the four components of the Higgs doublet, subject to the constraints of linearly realized SU(2)xU(1) electroweak symmetry. Up to terms that explicitly violate the shift symmetries, the effective lagrangian can be derived, irrespective of the spontaneously broken group G in the ultraviolet, and is universal in all models where the Higgs arises as a pseudo-Nambu-Goldstone boson (PNGB). Very high energy scatterings of vector bosons could provide smoking gun signals of a minimally symmetric Higgs boson.

  4. Symmetric nested complexes of fullerenes.

    PubMed

    Mar, Naveicy; Sansores, Luis Enrique; Muhl, Stephen; Ramos, Estrella; Salcedo, Roberto

    2015-04-01

    Large fullerenes such as C180 and C116 can be used as hosts for other molecules of the same family. Based on this idea, two complexes were designed, one in which C180 accepts a C60 molecule as a guest and the other in which C20 was placed inside C116. The behavior of these new assemblies was closer to that of a large endohedral complex rather than onion-like. There were marked differences between the systems. In the first system, there was minor interaction between the two cages but the association resulted in a more stable thermodynamic state. In the second system, there was strong electronic interchange between the cages, and the thermodynamic results suggest that such a combination might be useful for forming stable C20. PMID:25823391

  5. Dark matter on top

    NASA Astrophysics Data System (ADS)

    Gómez, M. A.; Jackson, C. B.; Shaughnessy, G.

    2014-12-01

    We consider a simplified model of fermionic dark matter which couples exclusively to the right-handed top quark via a renormalizable interaction with a color-charged scalar. We first compute the relic abundance of this type of dark matter and investigate constraints placed on the model parameter space by the latest direct detection data. We also perform a detailed analysis for the production of dark matter at the LHC for this model. We find several kinematic variables that allow for a clean signal extraction and we show that the parameter space of this model will be well probed during LHC Run-II. Finally, we investigate the possibility of detecting this type of dark matter via its annihilations into gamma rays. We compute the continuum and the line emission (which includes a possible ''Higgs in Space!'' line) and its possible discovery by future gamma-ray telescopes. We find that the annihilation spectrum has distinctive features which may distinguish it from other models.

  6. Symmetric coupling of angular momenta, quadratic algebras and discrete polynomials

    NASA Astrophysics Data System (ADS)

    Aquilanti, V.; Marinelli, D.; Marzuoli, A.

    2014-03-01

    Eigenvalues and eigenfunctions of the volume operator, associated with the symmetric coupling of three SU(2) angular momentum operators, can be analyzed on the basis of a discrete Schrödinger-like equation which provides a semiclassical Hamiltonian picture of the evolution of a 'quantum of space', as shown by the authors in [1]. Emphasis is given here to the formalization in terms of a quadratic symmetry algebra and its automorphism group. This view is related to the Askey scheme, the hierarchical structure which includes all hypergeometric polynomials of one (discrete or continuous) variable. Key tool for this comparative analysis is the duality operation defined on the generators of the quadratic algebra and suitably extended to the various families of overlap functions (generalized recoupling coefficients). These families, recognized as lying at the top level of the Askey scheme, are classified and a few limiting cases are addressed.

  7. Maximum tunneling velocities in symmetric double well potentials

    E-print Network

    Manz, Jörn; Schmidt, Burkhard; Yang, Yonggang

    2014-01-01

    We consider coherent tunneling of one-dimensional model systems in non-cyclic or cyclic symmetric double well potentials. Generic potentials are constructed which allow for analytical estimates of the quantum dynamics in the non-relativistic deep tunneling regime, in terms of the tunneling distance, barrier height and mass (or moment of inertia). For cyclic systems, the results may be scaled to agree well with periodic potentials for which semi-analytical results in terms of Mathieu functions exist. Starting from a wavepacket which is initially localized in one of the potential wells, the subsequent periodic tunneling is associated with tunneling velocities. These velocities (or angular velocities) are evaluated as the ratio of the flux densities versus the probability densities. The maximum velocities are found under the top of the barrier where they scale as the square root of the ratio of barrier height and mass (or moment of inertia), independent of the tunneling distance. They are applied exemplarily to ...

  8. Top dilepton search at CDF

    SciTech Connect

    The CDF Collaboration

    1993-08-01

    The authors present preliminary results from a search for the top quark in the dilepton channel using data collected by CDF during the 1992--93 Fermilab Collider Run. The dilepton analysis implies a lower limit on the top quark mass of 113 GeV/c{sup 2} at the 95% confidence level, assuming Standard Model decays.

  9. Detecting Symmetry and Symmetric Constellations of Features

    Microsoft Academic Search

    Gareth Loyand; Jan-olof Eklundh

    2006-01-01

    A novel and efficient method is presented for grouping feature points on the basis of their underlying symmetry and characterising the symmetries present in an image. We show how symmetric pairs of features can be efficiently detected, how the symmetry bonding each pair is extracted and evaluated, and how these can be grouped into symmetric constellations that specify the domi-

  10. Continuity and Separation in Symmetric Topologies

    ERIC Educational Resources Information Center

    Harris, J.; Lynch, M.

    2007-01-01

    In this note, it is shown that in a symmetric topological space, the pairs of sets separated by the topology determine the topology itself. It is then shown that when the codomain is symmetric, functions which separate only those pairs of sets that are already separated are continuous, generalizing a result found by M. Lynch.

  11. Nondissociative electron attachment to molecules and clusters

    NASA Astrophysics Data System (ADS)

    Fabrikant, I. I.

    2005-08-01

    We present results of effective range theory calculations of nondissociative electron attachment to SF6 molecules and CO2 clusters. The first process is strongly influenced by the SF-6 virtual state, and the second by vibrational Feshbach resonances associated with electron capture by the long-range polarization field of the cluster with simultaneous vibrational excitation of one molecular unit. We also study how both processes depend on the initial vibrational excitation of the target. We obtain a noticeable dependence of the attachment cross-section on the symmetric stretch vibration of SF6, although it does not lead to a significant temperature dependence at low electron energies.

  12. Greenhouse Gas Molecules

    NSDL National Science Digital Library

    Beloit College

    This page, from Beloit College, uses a Java application to allow users to view and rotate greenhouse gas molecules. Users may choose to view the molecule as a ball and/or stick model or a spacefill model.

  13. Turbulence near thunderstorm tops

    NASA Technical Reports Server (NTRS)

    Lester, Peter F.

    1993-01-01

    For several years, scientists at San Jose State University, NASA-Ames, and the University of Arizona have carried out cooperative research programs to understand the causes and effects of severe turbulence. The primary sources of data for this work are Digital Flight Data Recorder (DFDR) tapes from airliners that have been involved in turbulence incidents. A significant result of the analysis of these data has been the identification and quantification of the turbulence causes. Turbulence signatures include breaking Kelvin-Helmholtz waves, large amplitude mountain lee waves, turbulence in and around thunderstorms, and maneuvering. The requirements that must be met for a turbulence incident to be included in the NASA study are rather straightforward: (1) severe or greater turbulence must have been reported (usually with passenger injuries) and (2) the flight data tapes must be available. Despite these rather general criteria, and the fact that our cases are drawn from a wide geographical area over the U.S. and the Atlantic Ocean, we have found an interesting bias in our sample. Of 12 cases at cruise altitude, four were definitely associated with thunderstorms and two are suspected thunderstorm cases. The others were due to mountain waves, CAT, high level windshear/maneuvering, or to causes not yet determined. Although our sample is small, these numbers have raised several questions, not the least of which are: How pervasive is the problem of aircraft encounters with severe turbulence in or near thunderstorm tops (TNTT)? Given the available visible and radar evidence of thunderstorms, Why do such incidents occur? Can anything be done to allevaite the problem? This paper outlines some very preliminary efforts to answer these questions. In the following sections, physical and statistical characteristics of TNTT are discussed (Section 2), TNTT causes are summarized (Section 3), current recommendations for TNTT avoidance are reviewed (Section 4), and some suggestions to ameliorate the problem are given (Section 5).

  14. Resolution by Unassisted Top3 Points to Template Switch Recombination Intermediates during DNA Replication*

    PubMed Central

    Glineburg, M. Rebecca; Chavez, Alejandro; Agrawal, Vishesh; Brill, Steven J.; Johnson, F. Brad

    2013-01-01

    The evolutionarily conserved Sgs1/Top3/Rmi1 (STR) complex plays vital roles in DNA replication and repair. One crucial activity of the complex is dissolution of toxic X-shaped recombination intermediates that accumulate during replication of damaged DNA. However, despite several years of study the nature of these X-shaped molecules remains debated. Here we use genetic approaches and two-dimensional gel electrophoresis of genomic DNA to show that Top3, unassisted by Sgs1 and Rmi1, has modest capacities to provide resistance to MMS and to resolve recombination-dependent X-shaped molecules. The X-shaped molecules have structural properties consistent with hemicatenane-related template switch recombination intermediates (Rec-Xs) but not Holliday junction (HJ) intermediates. Consistent with these findings, we demonstrate that purified Top3 can resolve a synthetic Rec-X but not a synthetic double HJ in vitro. We also find that unassisted Top3 does not affect crossing over during double strand break repair, which is known to involve double HJ intermediates, confirming that unassisted Top3 activities are restricted to substrates that are distinct from HJs. These data help illuminate the nature of the X-shaped molecules that accumulate during replication of damaged DNA templates, and also clarify the roles played by Top3 and the STR complex as a whole during the resolution of replication-associated recombination intermediates. PMID:24100144

  15. Better Hadronic Top Quark Polarimetry

    E-print Network

    Brock Tweedie

    2014-11-03

    Observables sensitive to top quark polarization are important for characterizing or even discovering new physics. The most powerful spin analyzer in top decay is the down-type fermion from the W, which in the case of leptonic decay allows for very clean measurements. However, in many applications it is useful to measure the polarization of hadronically decaying top quarks. Usually it is assumed that at most 50% of the spin analyzing power can be recovered in this case. This paper introduces a simple and truly optimal hadronic spin analyzer, with a power of 64% at leading-order. The improvement is demonstrated to be robust at next-to-leading order, and in a handful of simulated measurements including the spins and spin correlations of boosted top quarks from multi-TeV top-antitop resonances, the spins of semi-boosted tops from chiral stop decays, and the potentially CP-violating spin correlations induced in continuum top pairs by color dipole operators. For the boosted studies, we explore jet substructure techniques that exhibit improved mapping between subjets and quarks.

  16. Patterns of energy levels and spectra for polyatomic molecules

    SciTech Connect

    Harter, W.G.

    1983-01-01

    Laser spectroscopy has revealed a remarkable intricacy in the rotational, vibrational, and electronic energy levels for polyatomic molecules. The infrared spectra of SF/sub 6/, CF/sub 4/, and related molecules contain several levels of structure on top of structure which resembles a fractal in some ways. The purpose of this article will be to exhibit some of this structure and introduce the simplest theoretical interpretations of it which are presently available.

  17. Training Top 10 Hall of Fame

    ERIC Educational Resources Information Center

    Training, 2012

    2012-01-01

    Microsoft Corporation and SCC Soft Computer are the newest inductees into the Training Top 10 Hall of Fame, joining the ranks of the 11 companies named to the hall since its inception in 2008 (Wyeth Pharmaceuticals subsequently was acquired by Pfizer Inc. in 2009). These 11 companies held Top 10 spots in the Training Top 50, Top 100, and now Top

  18. Magnetic control of a meta-molecule.

    PubMed

    Stenning, Gavin B G; Bowden, Graham J; Maple, Lewis C; Gregory, Simon A; Sposito, Alberto; Eason, Robert W; Zheludev, Nikolay I; de Groot, Peter A J

    2013-01-28

    Metamaterials offer the prospect of new science and applications. They have been designed by shaping or changing the material of the individual meta-molecules to achieve properties not naturally attainable. Composite meta-molecules incorporating a magnetic component offer new opportunities. In this work we report on the interaction between a non-magnetic split ring resonator (SRR) and a thin film of yttrium iron garnet (YIG). Strong hybridized resonances are observed. While the SRR is characterized by a magnetic and electric resonance, in practice, it is found that the YIG couples strongly to this symmetric (electric) mode of the SRR. It is also demonstrated that the anti-crossing region provides fertile ground for the creation of elementary excitations such as backward volume magnetostatic waves. PMID:23389127

  19. Intermittency on catalysts: symmetric exclusion

    E-print Network

    J. Gaertner; F. den Hollander; G. Maillard

    2006-05-24

    We continue our study of intermittency for the parabolic Anderson equation $\\partial u/\\partial t = \\kappa\\Delta u + \\xi u$, where $u\\colon \\Z^d\\times [0,\\infty)\\to\\R$, $\\kappa$ is the diffusion constant, $\\Delta$ is the discrete Laplacian, and $\\xi\\colon \\Z^d\\times [0,\\infty)\\to\\R$ is a space-time random medium. The solution of the equation describes the evolution of a ``reactant'' $u$ under the influence of a ``catalyst'' $\\xi$. In this paper we focus on the case where $\\xi$ is exclusion with a symmetric random walk transition kernel, starting from equilibrium with density $\\rho\\in (0,1)$. We consider the annealed Lyapunov exponents, i.e., the exponential growth rates of the successive moments of $u$. We show that these exponents are trivial when the random walk is recurrent, but display an interesting dependence on the diffusion constant $\\kappa$ when the random walk is transient, with qualitatively different behavior in different dimensions. Special attention is given to the asymptotics of the exponents for $\\kappa\\to\\infty$, which is controlled by moderate deviations of $\\xi$ requiring a delicate expansion argument. In G\\"artner and den Hollander \\cite{garhol04} the case where $\\xi$ is a Poisson field of independent (simple) random walks was studied. The two cases show interesting differences and similarities. Throughout the paper, a comparison of the two cases plays a crucial role.

  20. Baryon symmetric big bang cosmology

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1978-01-01

    Both the quantum theory and Einsteins theory of special relativity lead to the supposition that matter and antimatter were produced in equal quantities during the big bang. It is noted that local matter/antimatter asymmetries may be reconciled with universal symmetry by assuming (1) a slight imbalance of matter over antimatter in the early universe, annihilation, and a subsequent remainder of matter; (2) localized regions of excess for one or the other type of matter as an initial condition; and (3) an extremely dense, high temperature state with zero net baryon number; i.e., matter/antimatter symmetry. Attention is given to the third assumption, which is the simplest and the most in keeping with current knowledge of the cosmos, especially as pertains the universality of 3 K background radiation. Mechanisms of galaxy formation are discussed, whereby matter and antimatter might have collided and annihilated each other, or have coexisted (and continue to coexist) at vast distances. It is pointed out that baryon symmetric big bang cosmology could probably be proved if an antinucleus could be detected in cosmic radiation.

  1. PT-symmetric laser absorber

    NASA Astrophysics Data System (ADS)

    Longhi, Stefano

    2010-09-01

    In a recent work, Y. D. Chong [Phys. Rev. Lett.0031-900710.1103/PhysRevLett.105.053901 105, 053901 (2010)] proposed the idea of a coherent perfect absorber (CPA) as the time-reversed counterpart of a laser, in which a purely incoming radiation pattern is completely absorbed by a lossy medium. The optical medium that realizes CPA is obtained by reversing the gain with absorption, and thus it generally differs from the lasing medium. Here it is shown that a laser with an optical medium that satisfies the parity-time (PT) symmetry condition ?(-r)=?*(r) for the dielectric constant behaves simultaneously as a laser oscillator (i.e., it can emit outgoing coherent waves) and as a CPA (i.e., it can fully absorb incoming coherent waves with appropriate amplitudes and phases). Such a device can thus be referred to as a PT-symmetric CPA laser. The general amplification or absorption features of the PT CPA laser below lasing threshold driven by two fields are determined.

  2. Scattering in spherically symmetric media.

    PubMed

    Perelman, A Y

    1979-07-01

    The scattering problem within a multilayered spherically symmetric medium due to a source of perturbation located in the external region is considered. Assuming that the refractive index and its derivative vary continuously, with the exception of a finite number of jump discontinuities, the electromagnetic field vectors are represented in terms of various well-known potentials suitable for describing the azimuthal dependence of the incident wave. The linear dependence between the permittivity and the specific conductivity is proved to be equivalent to the vanishing of the electric charge density. Exact expressions for the field energy characteristics in the external region have been derived without any supplementary suppositions with respect to the wave zone. Scattering from a dielectric coated sphere, whose refractive index is a continuous function while its derivative has two jump discontinuity points (a modified Mie problem), has been studied. The generalized van de Hulst phase angle transformation is introduced and used to show the coincidence of the cross sections for scattering and extinction for the transparent spherical shell mentioned. PMID:20212651

  3. Simultaneous Evaluation of Multiple Rotationally Excited States of Floppy Molecules Using Diffusion Monte Carlo

    NASA Astrophysics Data System (ADS)

    McCoy, Anne B.; Ford, Jason E.; Marlett, Melanie L.; Petit, Andrew S.

    2014-06-01

    In this work, an extension to diffusion Monte Carlo (DMC) is proposed, allowing for the simultaneous calculation of the energy and wave function of multiple rotationally excited states of floppy molecules. The total wave function is expanded into a set of Dirac ?-functions called walkers, while the rotational portion of the wave function is expanded in a symmetric top basis set. Each walker is given a rotational state vector containing coefficients for all states of interest. The positions of the atoms and the coefficients in the state vector evolve according to the split operator approximation of the quantum propagator. The method was benchmarked by comparing calculated rotation-vibration energies for H_3^+, H_2D^+, and H_3O^+ to experimental values. For low to moderate values of J, the resulting energies are within the statistical uncertainty of the calculation. Rotation-vibration coupling is captured through flexibility introduced in the form of the vibrational wave function. This coupling is found to increase with increasing J-values. Based on the success achieved through these systems, the method was applied to CH_5^+ and its deuterated isotopologues for v = 0, J ? 10. Based on these calculations, the energy level structure of CH_5^+ is found to resemble that for a of a spherical top, and excitations up to J = 10 displayed insignificant rotation-vibration coupling. Extensions of this approach that explicitly account for vibrations will also be discussed. ` A. S. Petit, J. E. Ford and A. B. McCoy, J. Phys. Chem. A, in press, K. D. Jordan Festschrift, DOI: 10.1021/jp408821a

  4. Symmetric Informationally Complete Measurements of Arbitrary Rank

    E-print Network

    D. M. Appleby

    2006-11-27

    There has been much interest in so-called SIC-POVMs: rank 1 symmetric informationally complete positive operator valued measures. In this paper we discuss the larger class of POVMs which are symmetric and informationally complete but not necessarily rank 1. This class of POVMs is of some independent interest. In particular it includes a POVM which is closely related to the discrete Wigner function. However, it is interesting mainly because of the light it casts on the problem of constructing rank 1 symmetric informationally complete POVMs. In this connection we derive an extremal condition alternative to the one derived by Renes et al.

  5. Target Space Pseudoduality Between Dual Symmetric Spaces

    E-print Network

    Orlando Alvarez

    2000-05-03

    A set of on shell duality equations is proposed that leads to a map between strings moving on symmetric spaces with opposite curvatures. The transformation maps "waves" on a riemannian symmetric space to "waves" on its dual riemannian symmetric space. This transformation preserves the energy momentum tensor though it is not a canonical transformation. The preservation of the energy momentum tensor has a natural geometrical interpretation. The transformation maps "particle-like solutions" into static "soliton-like solutions". The results presented here generalize earlier results of E. Ivanov.

  6. Nonlinear symmetric stability of planetary atmospheres

    SciTech Connect

    Bowman, J.C. [Texas Univ., Austin, TX (United States). Inst. for Fusion Studies; Shepherd, T.G. [Toronto Univ., ON (Canada). Dept. of Physics

    1994-11-01

    The energy-Casimir method is applied to the problem of symmetric stability in the context of a compressible, hydrostatic planetary atmosphere with a general equation of state. Linear stability criteria for symmetric disturbances to a zonally symmetric baroclinic flow are obtained. In the special case of a perfect gas the results of Stevens (1983) are recovered. Nonlinear stability conditions are also obtained that, in addition to implying linear stability, provide an upper bound on a certain positive-definite measure of disturbance amplitude.

  7. Top quark properties at ATLAS

    E-print Network

    Dilip Jana; for the ATLAS Collaboration

    2008-10-20

    The ATLAS potential for the study of the top quark properties and physics beyond the Standard Model in the top quark sector, is described. The measurements of the top quark charge, the spin and spin correlations, the Standard Model decay (t-> bW), rare top quark decays associated to flavour changing neutral currents (t-> qX with X = gluon, Z, photon) and ttbar resonances are discussed. The sensitivity of the ATLAS experiment is estimated for an expected luminosity of 1fb-1 at the LHC. The full simulation of the ATLAS detector is used. For the Standard Model measurements the expected precision is presented. For the tests of physics beyond the Standard Model, the 5 sigma discovery potential (in the presence of a signal) and the 95% Confidence Level (CL) limit (in the absence of a signal) are given.

  8. Trajectory correction propulsion for TOPS

    NASA Technical Reports Server (NTRS)

    Long, H. R.; Bjorklund, R. A.

    1972-01-01

    A blowdown-pressurized hydrazine propulsion system was selected to provide trajectory correction impulse for outer planet flyby spacecraft as the result of cost/mass/reliability tradeoff analyses. Present hydrazine component and system technology and component designs were evaluated for application to the Thermoelectric Outer Planet Spacecraft (TOPS); while general hydrazine technology was adequate, component design changes were deemed necessary for TOPS-type missions. A prototype hydrazine propulsion system was fabricated and fired nine times for a total of 1600 s to demonstrate the operation and performance of the TOPS propulsion configuration. A flight-weight trajectory correction propulsion subsystem (TCPS) was designed for the TOPS based on actual and estimated advanced components.

  9. Dark decay of Top quark

    DOE PAGESBeta

    Kong, Kyoungchui [Kansas; Lee, Hye-Sung [W&M, JLAB; Park, Myeonhun [Tokyo

    2014-04-01

    We suggest top quark decays as a venue to search for light dark force carriers. Top quark is the heaviest particle in the standard model whose decays are relatively poorly measured, allowing sufficient room for exotic decay modes from new physics. A very light (GeV scale) dark gauge boson (Z') is a recently highlighted hypothetical particle that can address some astrophysical anomalies as well as the 3.6 ? deviation in the muon g-2 measurement. We present and study a possible scenario that top quark decays as t ? b W + Z's. This is the same as the dominant top quark decay (t ? b W) accompanied by one or multiple dark force carriers. The Z' can be easily boosted, and it can decay into highly collimated leptons (lepton-jet) with large branching ratio. We discuss the implications for the Large Hadron Collider experiments including the analysis based on the lepton-jets.

  10. Top quark production at ATLAS and CMS

    E-print Network

    Luca Lista; on behalf of the ATLAS; CMS collaborations

    2014-05-20

    A review of the main recent results on top quark production from the ATLAS and CMS experiments is presented. Results on both electroweak single top quark production and strong top pair production are presented.

  11. Top 10 Products of 2011

    ERIC Educational Resources Information Center

    American School & University, 2011

    2011-01-01

    In 2011, American School & University (AS&U) showcased some of the hottest products in the industry. This article presents the top ten most requested products as determined by readers. The top one on the list is the Bulb crusher which can cut recycling costs by 50%, can hold 1,350 4-foot lamps in a single 55-gallon drum, can crush a 4-foot lamp in…

  12. Uncovering the single top: observation of electroweak top quark production

    SciTech Connect

    Benitez, Jorge Armando; /Michigan State U.

    2009-08-01

    The top quark is generally produced in quark and anti-quark pairs. However, the Standard Model also predicts the production of only one top quark which is mediated by the electroweak interaction, known as 'Single Top'. Single Top quark production is important because it provides a unique and direct way to measure the CKM matrix element V{sub tb}, and can be used to explore physics possibilities beyond the Standard Model predictions. This dissertation presents the results of the observation of Single Top using 2.3 fb{sup -1} of Data collected with the D0 detector at the Fermilab Tevatron collider. The analysis includes the Single Top muon+jets and electron+jets final states and employs Boosted Decision Tress as a method to separate the signal from the background. The resulting Single Top cross section measurement is: (1) {sigma}(p{bar p} {yields} tb + X, tqb + X) = 3.74{sub -0.74}{sup +0.95} pb, where the errors include both statistical and systematic uncertainties. The probability to measure a cross section at this value or higher in the absence of signal is p = 1.9 x 10{sup -6}. This corresponds to a standard deviation Gaussian equivalence of 4.6. When combining this result with two other analysis methods, the resulting cross section measurement is: (2) {sigma}(p{bar p} {yields} tb + X, tqb + X) = 3.94 {+-} 0.88 pb, and the corresponding measurement significance is 5.0 standard deviations.

  13. Non-symmetrical bent-shaped compounds containing a chiral moiety

    Microsoft Academic Search

    Vladimíra Novotná; Kinga Mieczkowska; V?ra Hamplová; Attila Domján; Damian Pociecha; Miroslav Kašpar; Katalin Fodor-Csorba

    2012-01-01

    The synthesis and mesomorphic properties of new non-symmetrical bent-shaped compounds containing a chiral moiety are reported. These materials were built up from 3-hydroxybenzoic acid as a central unit with a chiral terminal group derived from lactic acid. A columnar phase of the B1REV type with tilted molecules was observed in a wide temperature range down to room temperature. The ferroelectric-like

  14. The nature of the bonding in symmetrical pincer palladacycles.

    PubMed

    Boonseng, Sarote; Roffe, Gavin W; Spencer, John; Cox, Hazel

    2015-04-01

    The accuracy of DFT-optimised geometries of the symmetrical pincer palladacycles PdNCN and PdSCS, [ClPd{2,6-(Me2NCH2)2C6H3}] and [ClPd{2,6-(MeSCH2)2C6H3}] respectively, has been evaluated by investigating the performance of eight commonly used density functionals with four combinations of basis set, in reproducing their X-ray crystal structures. It was found that whilst the ?B97XD functional performed best over all, the PBE and TPSS functionals performed best when considering the palladium coordination geometry. The role of the donor atom in the stability and reactivity of the symmetric palladacycles, PdYCY, Y = N, S, or P, has been determined using Bader's Atoms in Molecules method to elucidate the nature of the bonding, and using a model formation reaction, which involves the C-H activation of the pincer ligand YCY by PdCl2. The calculations reveal distinct differences in the bond strength and nature of the interaction of Pd with the donor atoms Y, which support differences in the thermodynamic stability of the palladacycles. PMID:25811120

  15. Trapping polar molecules in an ac trap

    SciTech Connect

    Bethlem, Hendrick L. [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany); Laser Centre Vrije Universiteit, De Boelelaan 1081, NL-1081HV Amsterdam (Netherlands); Veldhoven, Jacqueline van [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany); FOM-Institute for Plasmaphysics Rijnhuizen, P.O. Box 1207, NL-3430 BE Nieuwegein (Netherlands); Schnell, Melanie; Meijer, Gerard [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany)

    2006-12-15

    Polar molecules in high-field seeking states cannot be trapped in static traps as Maxwell's equations do not allow a maximum of the electric field in free space. It is possible to generate an electric field that has a saddle point by superposing an inhomogeneous electric field to an homogeneous electric field. In such a field, molecules are focused along one direction, while being defocused along the other. By reversing the direction of the inhomogeneous electric field the focusing and defocusing directions are reversed. When the fields are being switched back and forth at the appropriate rate, this leads to a net focusing force in all directions. We describe possible electrode geometries for creating the desired fields and discuss their merits. Trapping of {sup 15}ND{sub 3} ammonia molecules in a cylindrically symmetric ac trap is demonstrated. We present measurements of the spatial distribution of the trapped cloud as a function of the settings of the trap and compare these to both a simple model assuming a linear force and to full three-dimensional simulations of the experiment. With the optimal settings, molecules within a phase-space volume of 270 mm{sup 3} (m/s){sup 3} remain trapped. This corresponds to a trap depth of about 5 mK and a trap volume of about 20 mm{sup 3}.

  16. Time-Symmetric Quantum Theory of Smoothing

    E-print Network

    Tsang, Mankei

    Smoothing is an estimation technique that takes into account both past and future observations and can be more accurate than filtering alone. In this Letter, a quantum theory of smoothing is constructed using a time-symmetric ...

  17. A survey of spherically symmetric spacetimes

    NASA Astrophysics Data System (ADS)

    Parry, Alan R.

    2014-12-01

    We survey many of the important properties of spherically symmetric spacetimes as follows. We present several different ways of describing a spherically symmetric spacetime and the resulting metrics. We then focus our discussion on an especially useful form of the metric of a spherically symmetric spacetime in polar-areal coordinates and its properties. In particular, we show how the metric component functions chosen are extremely compatible with notions in Newtonian mechanics. We also show the monotonicity of the Hawking mass in these coordinates. As an example, we discuss how these coordinates and the metric can be used to solve the spherically symmetric Einstein-Klein-Gordon equations. We conclude with a brief mention of some applications of these properties.

  18. PT Symmetric Quantum Electrodynamics Carl M. Bender #

    E-print Network

    Milton, Kim

    PT ­Symmetric Quantum Electrodynamics Carl M. Bender # Theoretical Physics, Blackett Laboratory, Norman, OK 73019, USA (Dated: January 21, 2005) Abstract The Hamiltonian for quantum electrodynamics­ Hermitian quantum electrodynamics is constructed perturbatively. This construction demonstrates

  19. A Survey of Spherically Symmetric Spacetimes

    E-print Network

    Alan R. Parry

    2014-09-20

    We survey many of the important properties of spherically symmetric spacetimes as follows. We present several different ways of describing a spherically symmetric spacetime and the resulting metrics. We then focus our discussion on an especially useful form of the metric of a spherically symmetric spacetime in polar-areal coordinates and its properties. In particular, we show how the metric component functions chosen are extremely compatible with notions in Newtonian mechanics. We also show the monotonicity of the Hawking mass in these coordinates. As an example, we discuss how these coordinates and the metric can be used to solve the spherically symmetric Einstein-Klein-Gordon equations. We conclude with a brief mention of some applications of these properties.

  20. Spherically symmetric brane spacetime with bulk gravity

    NASA Astrophysics Data System (ADS)

    Chakraborty, Sumanta; SenGupta, Soumitra

    2015-01-01

    Introducing term in the five-dimensional bulk action we derive effective Einstein's equation on the brane using Gauss-Codazzi equation. This effective equation is then solved for different conditions on dark radiation and dark pressure to obtain various spherically symmetric solutions. Some of these static spherically symmetric solutions correspond to black hole solutions, with parameters induced from the bulk. Specially, the dark pressure and dark radiation terms (electric part of Weyl curvature) affect the brane spherically symmetric solutions significantly. We have solved for one parameter group of conformal motions where the dark radiation and dark pressure terms are exactly obtained exploiting the corresponding Lie symmetry. Various thermodynamic features of these spherically symmetric space-times are studied, showing existence of second order phase transition. This phenomenon has its origin in the higher curvature term with gravity in the bulk.

  1. Time Symmetric Quantum Cosmology and Our Universe

    E-print Network

    Raymond Laflamme

    1993-01-08

    We investigate the time neutral formulation of quantum cosmology of Gell-Mann and Hartle. In particular we study the proposal discussed by them that our Universe corresponds to the time symmetric decoherence functional with initial and final density matrix of low entropy. We show that our Universe does not correspond to this proposal by investigating the behaviour of small inhomogeneous perturbations around a Friedman-Robertson-Walker model. These perturbations cannot be time symmetric if they were small at the Big Bang.

  2. Symmetric-key cryptosystem with DNA technology

    Microsoft Academic Search

    Mingxin Lu; Xuejia Lai; Guozhen Xiao; Lei Qin

    2007-01-01

    DNA cryptography is a new field which has emerged with progress in the research of DNA computing. In our study, a symmetric-key\\u000a cryptosystem was designed by applying a modern DNA biotechnology, microarray, into cryptographic technologies. This is referred\\u000a to as DNA symmetric-key cryptosystem (DNASC). In DNASC, both encryption and decryption keys are formed by DNA probes, while\\u000a its ciphertext is

  3. Complex symmetric matrices with strongly stable iterates

    NASA Technical Reports Server (NTRS)

    Tadmor, E.

    1985-01-01

    Complex-valued symmetric matrices are studied. A simple expression for the spectral norm of such matrices is obtained, by utilizing a unitarily congruent invariant form. A sharp criterion is provided for identifying those symmetric matrices whose spectral norm is not exceeding one: such strongly stable matrices are usually sought in connection with convergent difference approximations to partial differential equations. As an example, the derived criterion is applied to conclude the strong stability of a Lax-Wendroff scheme.

  4. Optical Simulation of Axially Symmetrical Vertically Aligned Liquid Crystal Displays With Circularly Symmetric Iso-Contrast

    Microsoft Academic Search

    Cheng-Kai Liu; Chi-Lun Ting; Ming-Shian Li; Andy Ying-Guey Fuh; Ko-Ting Cheng

    2011-01-01

    This investigation reports the optical simulation of axially symmetric vertically aligned liquid crystal displays (ASVA LCDs). The circularly symmetric iso-light leakage and iso-transmittance contours of one subpixel result in the circularly symmetric iso-contrast contours. The contrast ratio of the area close to - and -axes at a polar angle of around 30 exceeds 10. The LCs near some azimuthal angles

  5. Electrical readouts of single and few molecule systems in metal-molecule-metal device structures.

    PubMed

    Mahapatro, Ajit K; Janes, David B

    2007-06-01

    Electrical conduction through molecular junctions are measured in different local environments through two test beds that are ideal for single/few molecule and molecular monolayer systems. A technique has been developed to realize Au films with approximately 1.5 A surface roughness comparable to the best available techniques and suitable for formation of patterned device structures. The technique utilizes room temperature e-beam evaporated Au films over oxidized Si substrates silanized with (3-mercaptopropyl)trimethoxysilane (MPTMS). The lateral (single/few molecule) and vertical (many molecules) device structures are both enabled by the process for realizing ultraflat Au layer. Lateral metal-molecule-metal (M-M-M) device structures are fabricated by forming pairs of Au electrodes with nanometer separation (nano-gap) through an electromigration-induced break-junction (EIBJ) technique at room temperature and conductivity measurements are carried out for dithiol functionalized single molecules. We have used the flat Au layer (using the current technique) as the bottom contact in vertical M-M-M device structures. Here, molecular self-assembly are formed on the Au surface, and patterned (20 x 20 microm2) top Au contacts were successfully transferred on to the device using a stamping technique (where the Au is deposited on a polydimethylsiloxane (PDMS) pad and following a physical contact on the thiolated Au layer). The single molecular property of XYL, a highly conductive molecule and many molecular property of HS-C9-SH, an insulating molecule in its molecular monolayer form are measured. Observation of enhanced conduction following molecular deposition, and comparison of conductance-voltage characteristics to those predicted theoretically, confirms the success of trapping single/few molecules in the nano-gap. The observed approximately 10(2) less conductance through the molecular monolayer of HS-C9-SH compared to the estimation of a linear sum of single molecule conductances over large area indicate that either all the molecules are not in physical contact with the top stamping electrode or electrode-molecule coupling has a less broadening in presence of it own environment or both. PMID:17655006

  6. Informational approach to the quantum symmetrization postulate

    NASA Astrophysics Data System (ADS)

    Goyal, Philip

    2015-01-01

    A remarkable feature of quantum theory is that particles with identical intrinsic properties must be treated as indistinguishable if the theory is to give valid predictions in all cases. In the quantum formalism, indistinguishability is expressed via the symmetrization postulate (Dirac P 1926 Proc. R. Soc. A 112 661, Heisenberg W 1926 Z. Phys. 38 411), which restricts a system of identical particles to the set of symmetric states (‘bosons’) or the set of antisymmetric states (‘fermions’). However, the physical basis and range of validity of the symmetrization postulate has not been established. A well-known topological derivation of the postulate implies that its validity depends on the dimensionality of the space in which the particles move (Laidlaw M and DeWitt C 1971 Phys. Rev. D 3 1375–8, Leinaas J M and Myrheim J 1977 Il Nuovo Cimento B 37 1–23). Here we show that the symmetrization postulate can be derived by strictly adhering to the informational requirement that particles which cannot be experimentally distinguished from one another are not labelled. Our key novel postulate is the operational indistinguishability postulate, which posits that the amplitude of a process involving several indistinguishable particles is determined by the amplitudes of all possible transitions of these particles when treated as distinguishable. The symmetrization postulate follows by requiring consistency with the rest of the quantum formalism. The derivation implies that the symmetrization postulate admits no natural variants. In particular, the possibility that identical particles generically exhibit anyonic behavior in two dimensions is excluded.

  7. Current through single conjugated molecules: calculations versus measurements.

    PubMed

    Liang, Y Y; Zhou, Y X; Chen, H; Note, R; Mizuseki, H; Kawazoe, Y

    2008-07-14

    We use density functional theory based nonequilibrium Green's function to calculate the current through the different rodlike molecules at the finite temperatures self-consistently, which was compared to the experimental measurements presented by Reichert et al. [Phys. Rev. Lett. 88, 176804 (2002)] and by Mayor et al. [Angew. Chem. Int. Ed. 42, 5834 (2003)], respectively. Our results agree with the measurements very well, especially for the bias around +/-1.0 V. The investigation of the topological effect for the symmetrical molecule reveals the fact that the para position compound provides a considerably larger conductance than the meta one. PMID:18624557

  8. Photoluminescence mapping of coupled and detuned states in photonic molecules

    E-print Network

    Brossard, F S F; Chan, C C S; Xu, X L; Griffiths, J P; Williams, D A; Murray, R; Taylor, R A

    2013-01-01

    We study the coupling of cavities embedded in a photonic crystal waveguide and report the clear signature of a strongly coupled system using photoluminescence microscopy. In particular, we are able to spatially map the profile of the antisymmetric (antibonding) and symmetric (bonding) modes of a pair of coupled cavities (photonic molecule) defined by the local modulation of the waveguide width. The mode localization observed in either cavity due to structural disorder are reproduced numerically by nm shift in the waveguide modulation.

  9. Direct calculation of centrifugal-distortion constants and inertial defects of XY3-type plane molecules from experimental data

    Microsoft Academic Search

    V. F. Pulin; E. I. Kredentser; L. M. Sverdlov

    1978-01-01

    A simple direct method is proposed for the calculation of the centrifugal-distortion constants taualphabetagammadelta and inertial defects of plane symmetric molecules of type XY3 from the experimental frequencies, Coriolis constant zeta33, and geometric parameters. The calculation formulas are given, together with the results obtained for the BF3, BCl3, BI3, BBr3, and SO3 molecules.

  10. Direct calculation of centrifugal-distortion constants and inertial defects of XY 3 -type plane molecules from experimental data

    Microsoft Academic Search

    V. F. Pulin; E. I. Kredentser; L. M. Sverdlov

    1978-01-01

    A simple direct method is proposed for the calculation of the centrifugal-distortion constants taß?d and inertial defects of plane symmetric molecules of type XY3 from the experimental frequencies, Coriolis constant ?33, and geometric parameters. The calculation formulas are given, together with the results obtained for the BF3, BCl3, BI3, BBr3, and SO3 molecules.

  11. Molecules between the Stars.

    ERIC Educational Resources Information Center

    Verschuur, Gerrit L.

    1987-01-01

    Provides a listing of molecules discovered to date in the vast interstellar clouds of dust and gas. Emphasizes the recent discoveries of organic molecules. Discusses molecular spectral lines, MASERs (microwave amplification by stimulated emission of radiation), molecular clouds, and star birth. (TW)

  12. What is a Molecule?

    NSDL National Science Digital Library

    WPSU

    2007-04-09

    This video/animation shows that a molecule of water is made up of oxygen and hydrogen atoms. When oxygen and hydrogen atoms exist alone, their properties are different from the properties they have when they are chemically combined to form a water molecule

  13. Enzymatic DNA molecules

    NASA Technical Reports Server (NTRS)

    Joyce, Gerald F. (Inventor); Breaker, Ronald R. (Inventor)

    1998-01-01

    The present invention discloses deoxyribonucleic acid enzymes--catalytic or enzymatic DNA molecules--capable of cleaving nucleic acid sequences or molecules, particularly RNA, in a site-specific manner, as well as compositions including same. Methods of making and using the disclosed enzymes and compositions are also disclosed.

  14. Molecules in Living Systems

    NSDL National Science Digital Library

    2012-06-19

    This lesson explains the difference between molecules in living systems and inanimate objects. In living systems, atoms and molecules are organized to a much greater degree and provide the structure of the organism. Lipids, carbohydrates, proteins, and nucleic acids are also discussed.

  15. Decelerating Neutral Dipolar Molecules

    Microsoft Academic Search

    Hendrick L. Bethlem; Giel Berden; Gerard Meijer

    1999-01-01

    It is experimentally demonstrated that a beam of neutral dipolar molecules can be efficiently decelerated with a time-varying electric field. A pulsed beam of neutral metastable CO molecules is slowed down from 225 m\\/s ( Ekin = 59 cm-1) to 98 m\\/s ( Ekin = 11 cm-1) upon passage through an array of 63 synchronously pulsed electric field stages.

  16. Adhesion molecules and receptors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adhesion molecules are necessary for leukocyte trafficking and differentiation. They serve to initiate cell-cell interactions under conditions of shear, and they sustain the cell-cell and cell-matrix interactions needed for cellular locomotion. They also can serve directly as signaling molecules act...

  17. Symmetric Galerkin boundary formulations employing curved elements

    NASA Technical Reports Server (NTRS)

    Kane, J. H.; Balakrishna, C.

    1993-01-01

    Accounts of the symmetric Galerkin approach to boundary element analysis (BEA) have recently been published. This paper attempts to add to the understanding of this method by addressing a series of fundamental issues associated with its potential computational efficiency. A new symmetric Galerkin theoretical formulation for both the (harmonic) heat conduction and the (biharmonic) elasticity problem that employs regularized singular and hypersingular boundary integral equations (BIEs) is presented. The novel use of regularized BIEs in the Galerkin context is shown to allow straightforward incorporation of curved, isoparametric elements. A symmetric reusable intrinsic sample point (RISP) numerical integration algorithm is shown to produce a Galerkin (i.e., double) integration strategy that is competitive with its counterpart (i.e., singular) integration procedure in the collocation BEA approach when the time saved in the symmetric equation solution phase is also taken into account. This new formulation is shown to be capable of employing hypersingular BIEs while obviating the requirement of C 1 continuity, a fact that allows the employment of the popular continuous element technology. The behavior of the symmetric Galerkin BEA method with regard to both direct and iterative equation solution operations is also addressed. A series of example problems are presented to quantify the performance of this symmetric approach, relative to the more conventional unsymmetric BEA, in terms of both accuracy and efficiency. It is concluded that appropriate implementations of the symmetric Galerkin approach to BEA indeed have the potential to be competitive with, if not superior to, collocation-based BEA, for large-scale problems.

  18. Cold Metastable NH molecules

    NASA Astrophysics Data System (ADS)

    Fabrikant, Maya; Briles, Travis; Fitch, Noah; Lewandowski, Heather

    2011-06-01

    We report progress towards producing samples of cold trapped NH molecules using a stark decelerator. The NH molecule has a metastable state (a1Delta) approximately 1.5 eV above the ground state and a lifetime of several seconds. We create of a beam of cold NH molecules almost entirely in the a1 delta state by supersonic expansion and in situ photolysis of HNCO. We determine the rotational and translation temperatures of the beam using 2+1 resonance enhanced multi-photon ionization spectroscopy. The NH molecules are then slowed in a stark decelerator and trapped using static electric fields. Once the molecules are trapped, we will overlap a magnetic trap of ultracold rubidium atoms to study near-resonant quenching of metastable NH.

  19. Top Quark Property Measurements with ATLAS

    E-print Network

    Rudolph, Matthew Scott; The ATLAS collaboration

    2015-01-01

    In this talk I discuss recent ATLAS results on the properties of the top quark, focusing on results using the 2011 and 2012 data at 7 and 8 TeV. Results include top charge asymmetry, top-antitop spin correlation, and the mass of the top quark.

  20. What can be learned about molecular reorientation from single molecule polarization microscopy?

    Microsoft Academic Search

    M. F. Gelin; D. S. Kosov

    2006-01-01

    We have developed a general approach for the calculation of the single molecule polarization correlation function C(t), which delivers a correlation of the emission dichroisms at time 0 and t. The approach is model independent and valid for general asymmetric top molecules. The key dynamic quantities of our analysis are the even-rank orientational correlation functions, the weighted sum of which

  1. Top Quark Spin Correlations - Theory

    SciTech Connect

    Parke, Stephen J.; /Fermilab

    2012-02-01

    The top quark decay width (G{sub F}m{sub t}{sup 3} {approx} 1 GeV) is much larger than the QCD hadronization scale ({Lambda}{sub QCD} {approx} 0.1 GeV) and much larger than the spin decorrelation scale ({Lambda}{sub QCD}{sup 2}/m{sub t} {approx} 0.1 MeV). Therefore, spin correlations in top quark pair production are reflected in angular correlations of the decay products, see [1] and [2].

  2. MHD Integrated Topping Cycle Project

    NASA Astrophysics Data System (ADS)

    1992-01-01

    The Magnetohydrodynamics (MHD) Integrated Topping Cycle (ITC) Projects represents the culmination of the proof-of-concept (POC) development stage in the U.S. Department of Energy (DOE) program to advance MHD technology to the early commercial development stage utility power applications. The project is a joint effort, combining the skills of three topping cycle component developers: TRW, Avco, and Westinghouse. TRW, the prime contractor and system integrator, is responsible for the 50 thermal megawatt slagging coal combustion subsystem. Avco is responsible for the MHD channel subsystem (nozzle, channel, diffuser, and power conditioning circuits). Westinghouse is responsible for the current consolidation subsystem.

  3. Elements of Cryptography.Elements of Cryptography. Symmetric Encryption.Symmetric Encryption.

    E-print Network

    Fisher, Michael

    COMP 522 Elements of Cryptography.Elements of Cryptography. Symmetric Encryption.Symmetric Encryption. NSE, sections 2.1-2.2 WSPC, chapter 3 COMP 522 Cryptography · Cryptography is a collection of mathematical techniques for protecting information; · Most important technique is encryption/decryption; · We

  4. Synthesis and physical properties of symmetrical and non-symmetrical triacylglycerols containing two palmitic fatty acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Both the amounts of and specific structures of the triacylglycerols (TAG) present in the oil phase of a margarine or spread are considered responsible for such properties as its spreadability, resistance to water/oil loss, and melting characteristics. A series of symmetrical and non-symmetrical TAG...

  5. Symmetric curvature descriptors for label-free analysis of DNA

    NASA Astrophysics Data System (ADS)

    Buzio, Renato; Repetto, Luca; Giacopelli, Francesca; Ravazzolo, Roberto; Valbusa, Ugo

    2014-09-01

    High-resolution microscopy techniques such as electron microscopy, scanning tunnelling microscopy and atomic force microscopy represent well-established, powerful tools for the structural characterization of adsorbed DNA molecules at the nanoscale. Notably, the analysis of DNA contours allows mapping intrinsic curvature and flexibility along the molecular backbone. This is particularly suited to address the impact of the base-pairs sequence on the local conformation of the strands and plays a pivotal role for investigations relating the inherent DNA shape and flexibility to other functional properties. Here, we introduce novel chain descriptors aimed to characterize the local intrinsic curvature and flexibility of adsorbed DNA molecules with unknown orientation. They consist of stochastic functions that couple the curvatures of two nanosized segments, symmetrically placed on the DNA contour. We show that the fine mapping of the ensemble-averaged functions along the molecular backbone generates characteristic patterns of variation that highlight all pairs of tracts with large intrinsic curvature or enhanced flexibility. We demonstrate the practical applicability of the method for DNA chains imaged by atomic force microscopy. Our approach paves the way for the label-free comparative analysis of duplexes, aimed to detect nanoscale conformational changes of physical or biological relevance in large sample numbers.

  6. Lifetimes of spherically symmetric closed universes

    E-print Network

    Burnett, G A

    1995-01-01

    It is proven that any spherically symmetric spacetime that possesses a compact Cauchy surface \\Sigma and that satisfies the dominant-energy and non-negative-pressures conditions must have a finite lifetime in the sense that all timelike curves in such a spacetime must have a length no greater than 10 \\max_\\Sigma(2m), where m is the mass associated with the spheres of symmetry. This result gives a complete resolution, in the spherically symmetric case, of one version of the closed-universe recollapse conjecture (though it is likely that a slightly better bound can be established). This bound has the desirable properties of being computable from the (spherically symmetric) initial data for the spacetime and having a very simple form. In fact, its form is the same as was established, using a different method, for the spherically symmetric massless scalar field spacetimes, thereby proving a conjecture offered in that work. Prospects for generalizing these results beyond the spherically symmetric case are discusse...

  7. p-n configurations of symmetric and mixed-symmetric states

    NASA Astrophysics Data System (ADS)

    Perry, M.; Werner, V.; Pietralla, N.; Benczer-Koller, N.

    2006-10-01

    The first 2^+ state in collective even-even nuclei is a proton-neutron (pn) symmetric quadrupole excitation. It has a mixed-symmetric counterpart, which has p-n anti-symmetric parts in the wavefunction. A strong p-n interaction mixes the proton and neutron configuration, creating a low-lying symmetric state and a higher-lying mixed-symmetric state. The significant energy difference between the proton and neutron j=2 configurations and rather weak mixing between the proton and neutron state wavefunctions in Zr isotopes results in a 2^+1 state with neutron dominance and a 2^+2 state with proton dominance, which was identified as the one-phonon mixed-symmetry 2^+ state. This signature in Zr provides an ideal basis for studying configuration mixing. This mixing is studied experimentally by measuring g factors. Theoretical predictions will be compared with recent experimental results.

  8. Single molecule logical devices.

    PubMed

    Renaud, Nicolas; Hliwa, Mohamed; Joachim, Christian

    2012-01-01

    After almost 40 years of development, molecular electronics has given birth to many exciting ideas that range from molecular wires to molecular qubit-based quantum computers. This chapter reviews our efforts to answer a simple question: how smart can a single molecule be? In our case a molecule able to perform a simple Boolean function is a child prodigy. Following the Aviram and Ratner approach, these molecules are inserted between several conducting electrodes. The electronic conduction of the resulting molecular junction is extremely sensitive to the chemical nature of the molecule. Therefore designing this latter correctly allows the implementation of a given function inside the molecular junction. Throughout the chapter different approaches are reviewed, from hybrid devices to quantum molecular logic gates. We particularly stress that one can implement an entire logic circuit in a single molecule, using either classical-like intramolecular connections, or a deformation of the molecular orbitals induced by a conformational change of the molecule. These approaches are radically different from the hybrid-device approach, where several molecules are connected together to build the circuit. PMID:21826604

  9. The Top STEM Degree Producers

    ERIC Educational Resources Information Center

    Diverse: Issues in Higher Education, 2012

    2012-01-01

    This article presents a list of the top Science, Technology, Engineering, and Mathematics (STEM) degree producers in the U.S. This list is broken down into seven categories: (1) Total Minority Research/Scholarship and Other Doctoral: Mathematics and Statistics; (2) Total Minority Bachelors: Biological and Biomedical Sciences; (3) Total Minority…

  10. Conservation: Top predators and biodiversity

    Microsoft Academic Search

    Fabrizio Sergio; Ian Newton; Luigi Marchesi

    2005-01-01

    The charisma of top vertebrate predators is often used by conservationists as a lever for financial support, to raise environmental awareness and in planning protected areas - a strategy that has been criticized. Here we use information collected from five raptor species that differ widely in their diet and habitat associations to show that sites occupied by these predators are

  11. The 2002 Training Top 100.

    ERIC Educational Resources Information Center

    Training, 2002

    2002-01-01

    Identifies the top 100 companies in terms of the amount spent on training and development, the number of hours of training per employee, percentage of payroll spent on training, and tuition allotment per employee. Describes best practices in succession planning and leadership development, mentoring, and job shadowing and provides a detailed…

  12. The 2003 Training Top 100.

    ERIC Educational Resources Information Center

    Galvin, Tammy

    2003-01-01

    Identifies the top 100 U.S. companies in terms of the amount spent on training and development, the number of hours of training per employee, percentage of payroll spent on training, and tuition allotment per employee. Describes best practices in succession planning and leadership development, mentoring, and job shadowing and provides a detailed…

  13. Time Management Top 50 Strategies

    E-print Network

    See over Time Management Top 50 Strategies Don't try to do everything on this list all at once, acceptable to you, realistic, and time-specified. 6. Ensure that goals are consistent with your values. 7 your time. 10. Use calendars ­ term, weekly & daily. 11. Carry your daily schedule with you. 12

  14. Time Management Top 50 Strategies

    E-print Network

    See over Time Management Top 50 Strategies Don't try to do everything on this list all at once, and continually improve on how you spend your time. 10. Use calendars ­ term, weekly & daily. 11. Carry your up. 15. Figure out your peak times of day for energy and do difficult tasks (e.g.: studying) during

  15. Top 5 Majors 1. Accounting

    E-print Network

    Hemmers, Oliver

    Top 5 Majors 1. Accounting 2. Management 3. Marketing 4. Finance 5. Management Information Systems Survey Response Database. We used Survey Monkey to gather the data and report the responses from our online recruiting management system that includes job and internship postings, Resume Books, and On

  16. Department of Physics TOPS Facility

    E-print Network

    Strathclyde, University of

    . The incident is to be reported to the dept. RPS-lasers and the Safety Office (ext 2726) TOPS Facility Safety..................................................................................5 4. Laser Safety Eyewear and safety policy, section 10" of the university c. "guidance on the safe use of lasers in education

  17. Ordered structures of two sulfur containing donor molecules on the Au(111) surface

    NASA Astrophysics Data System (ADS)

    Fiedler, Benjamin; Rojo-Wiechel, Elena; Klassen, Johann; Simon, Julia; Beck, Johannes; Sokolowski, Moritz

    2012-12-01

    We report experiments by low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) on ordered structures of two sulfur-containing ?-conjugated molecules on the Au(111)-surface, namely tetrabenzothianthrene (TBTA) and tetrathiotetracene (TTT). These molecules are candidates for donors in charge transfer salts. On Au(111) both molecules form long-range ordered structures that are commensurate to the top-most surface layer. For TBTA, the reconstruction of the Au(111) surface is maintained, whereas it is lifted by TTT. Both molecules lie flat on the surface. For TBTA, the structure indicates that the molecule is planarized upon adsorption.

  18. Top Jets at the LHC

    SciTech Connect

    Almeida, L.G.; Lee, S.J.; Perez, G.; Sung, I.; Virzi, J.

    2008-10-06

    We investigatethe reconstruction of high pT hadronically-decaying top quarksat the Large Hadron Collider. One of the main challenges in identifying energetictop quarks is that the decay products become increasingly collimated. This reducesthe efficacy of conventional reconstruction methods that exploit the topology of thetop quark decay chain. We focus on the cases where the decay products of the topquark are reconstructed as a single jet, a"top-jet." The most basic"top-tag" methodbased on jet mass measurement is considered in detail. To analyze the feasibility ofthe top-tagging method, both theoretical and experimental aspects of the large QCDjet background contribution are examined. Based on a factorization approach, wederive a simple analytic approximation for the shape of the QCD jet mass spectrum.We observe very good agreement with the Monte Carlo simulation. We consider high pT tt bar production in the Standard Model as an example, and show that our theoretical QCD jet mass distributions can efficiently characterize the background via sideband analyses. We show that with 25 fb-1 of data, our approach allows us to resolve top-jets with pT _> 1 TeV, from the QCD background, and about 1.5 TeV top-jets with 100 fb-1, without relying on b-tagging. To further improve the significancewe consider jet shapes (recently analyzed in 0807.0234 [hep-ph]), which resolve thesubstructure of energy flow inside cone jets. A method of measuring the top quarkpolarization by using the transverse momentum of the bottom quark is also presented.The main advantages of our approach are: (i) the mass distributions are driven byfirst principle calculations, instead of relying solely on Monte Carlo simulation; (ii) for high pT jets (pT _> 1 TeV), IR-safe jet shape variables are robust against detectorresolution effects. Our analysis can be applied to other boosted massive particlessuch as the electroweak gauge bosons and the Higgs.

  19. Cervical Symmetric Dumbbell Ganglioneuromas Causing Severe Paresis

    PubMed Central

    Miyamoto, Kei; Hirose, Yoshinobu; Kito, Yusuke; Fushimi, Kazunari; Shimizu, Katsuji

    2014-01-01

    We report an extremely rare case with bilateral and symmetric dumbbell ganglioneuromas of the cervical spine in an elderly patient. A 72-year-old man came by ambulance to our hospital due to progressive incomplete paraplegia. Magnetic resonance imaging demonstrated bilateral symmetric dumbbell tumors at the C1/2 level. We performed total resection of the intracanalar tumor, aiming at complete decompression of the spinal cord, and partial and subtotal resection of foraminal outside portions. Histopathological examination of the surgical specimen indicated the tumor cells to be spindle cells with the presence of ganglion cells and no cellular pleomorphism, suggesting a diagnosis of ganglioneuroma. Although the surgery was not curative, the postoperative course was uneventful and provided a satisfactory outcome. This is the fourth known case of cervical ganglioneuromas of the bilateral symmetric dumbbell type. PMID:24596609

  20. Cervical symmetric dumbbell ganglioneuromas causing severe paresis.

    PubMed

    Hioki, Akira; Miyamoto, Kei; Hirose, Yoshinobu; Kito, Yusuke; Fushimi, Kazunari; Shimizu, Katsuji

    2014-02-01

    We report an extremely rare case with bilateral and symmetric dumbbell ganglioneuromas of the cervical spine in an elderly patient. A 72-year-old man came by ambulance to our hospital due to progressive incomplete paraplegia. Magnetic resonance imaging demonstrated bilateral symmetric dumbbell tumors at the C1/2 level. We performed total resection of the intracanalar tumor, aiming at complete decompression of the spinal cord, and partial and subtotal resection of foraminal outside portions. Histopathological examination of the surgical specimen indicated the tumor cells to be spindle cells with the presence of ganglion cells and no cellular pleomorphism, suggesting a diagnosis of ganglioneuroma. Although the surgery was not curative, the postoperative course was uneventful and provided a satisfactory outcome. This is the fourth known case of cervical ganglioneuromas of the bilateral symmetric dumbbell type. PMID:24596609

  1. Chiral light by symmetric optical antennas

    E-print Network

    Mekonnen, Addis; Zubritskaya, Irina; Jönsson, Gustav Edman; Dmitriev, Alexandre

    2014-01-01

    Chirality is at the origin of life and is ubiquitous in nature. An object is deemed chiral if it is non-superimposable with its own mirror image. This relates to how circularly polarized light interacts with such object, a circular dichroism, the differential absorption of right and left circularly polarized light. According to the common understanding in biology, chemistry and physics, the circular dichroism results from an internal chiral structure or external symmetry breaking by illumination. We show that circular dichroism is possible with simple symmetric optical nanoantennas at symmetric illumination. We experimentally and theoretically demonstrate that two electromagnetic dipole-like modes with a phase lag, in principle, suffice to produce circular dichroism in achiral structure. Examples of the latter are all visible spectrum optical nanoantennas, symmetric nanoellipses and nanodimers. The simplicity and generality of this finding reveal a whole new significance of the electromagnetic design at a nan...

  2. Symmetric extension of two-qubit states

    NASA Astrophysics Data System (ADS)

    Chen, Jianxin; Ji, Zhengfeng; Kribs, David; Lütkenhaus, Norbert; Zeng, Bei

    2014-09-01

    A bipartite state ?AB is symmetric extendible if there exists a tripartite state ?ABB' whose AB and AB' marginal states are both identical to ?AB. Symmetric extendibility of bipartite states is of vital importance in quantum information because of its central role in separability tests, one-way distillation of Einstein-Podolsky-Rosen pairs, one-way distillation of secure keys, quantum marginal problems, and antidegradable quantum channels. We establish a simple analytic characterization for symmetric extendibility of any two-qubit quantum state ?AB; specifically, tr(?B2)?tr(?AB2)-4? det?AB . As a special case we solve the bosonic three-representability problem for the two-body reduced density matrix.

  3. The quantum capacity with symmetric side channels

    E-print Network

    Graeme Smith; John A. Smolin; Andreas Winter

    2008-08-28

    We present an upper bound for the quantum channel capacity that is both additive and convex. Our bound can be interpreted as the capacity of a channel for high-fidelity quantum communication when assisted by a family of channels that have no capacity on their own. This family of assistance channels, which we call symmetric side channels, consists of all channels mapping symmetrically to their output and environment. The bound seems to be quite tight, and for degradable quantum channels it coincides with the unassisted channel capacity. Using this symmetric side channel capacity, we find new upper bounds on the capacity of the depolarizing channel. We also briefly indicate an analogous notion for distilling entanglement using the same class of (one-way) channels, yielding one of the few entanglement measures that is monotonic under local operations with one-way classical communication (1-LOCC), but not under the more general class of local operations with classical communication (LOCC).

  4. Systems of coupled PT-symmetric oscillators

    NASA Astrophysics Data System (ADS)

    Bender, Carl M.; Gianfreda, Mariagiovanna; Klevansky, S. P.

    2014-08-01

    The Hamiltonian for a PT-symmetric chain of coupled oscillators is constructed. It is shown that if the loss-gain parameter ? is uniform for all oscillators, then as the number of oscillators increases, the region of unbroken PT symmetry disappears entirely. However, if ? is localized in the sense that it decreases for more distant oscillators, then the unbroken PT-symmetric region persists even as the number of oscillators approaches infinity. In the continuum limit the oscillator system is described by a PT-symmetric pair of wave equations, and a localized loss-gain impurity leads to a pseudobound state. It is also shown that a planar configuration of coupled oscillators can have multiple disconnected regions of unbroken PT symmetry.

  5. Systems of coupled PT-symmetric oscillators

    E-print Network

    Carl M. Bender; Mariagiovanna Gianfreda; S. P. Klevansky

    2014-06-23

    The Hamiltonian for a PT-symmetric chain of coupled oscillators is constructed. It is shown that if the loss-gain parameter $\\gamma$ is uniform for all oscillators, then as the number of oscillators increases, the region of unbroken PT-symmetry disappears entirely. However, if $\\gamma$ is localized in the sense that it decreases for more distant oscillators, then the unbroken-PT-symmetric region persists even as the number of oscillators approaches infinity. In the continuum limit the oscillator system is described by a PT-symmetric pair of wave equations, and a localized loss-gain impurity leads to a pseudo-bound state. It is also shown that a planar configuration of coupled oscillators can have multiple disconnected regions of unbroken PT symmetry.

  6. Designing a small molecule erythropoietin mimetic.

    PubMed

    Guarnieri, Frank

    2015-01-01

    Erythropoietin (EPO) is a protein made by the kidneys in response to low red blood cell count that is secreted into the bloodstream and binds to a receptor on hematopoietic stem cells in the bone marrow inducing them to become new red blood cells. EPO made with recombinant DNA technology was brought to market in the 1980s to treat anemia caused by kidney disease and cancer chemotherapy. Because EPO infusion was able to replace blood transfusions in many cases, it rapidly became a multibillion dollar per year drug and as the first biologic created with recombinant technology it launched the biotech industry. For many years intense research was focused on creating a small molecule orally available EPO mimetic. The Robert Wood Johnson (RWJ) group seemed to definitively establish that only large peptides with a minimum of 60 residues could replace EPO, as anything less was not a full agonist. An intense study of the published work led me to hypothesize that the size of the mimetic is not the real issue, but the symmetry making and breaking of the EPO receptor induced by the ligand is the key to activating the stem cells. This analysis meant that residues in the binding site of the receptor deemed absolutely essential for ligand binding and activation from mutagenesis experiments, were probably not really that important. My fundamental hypotheses were: (a) the symmetric state of the homodimeric receptor is the most stable state and thus must be the off-state, (b) a highly localized binding site exists at a pivot point where the two halves of the receptor meet, (c) small molecules can be created that have high potency for this site that will be competitive with EPO and thus can displace the protein-protein interaction, (d) small symmetric molecules will stabilize the symmetric off-state of the receptor, and (e) a key asymmetry in the small molecule will stabilize a mirror image asymmetry in the receptor resulting in the stabilization of the on-state and proliferation of the stem cells into red blood cells. Researchers at Amgen published a co-crystal structure of EPO bound to the EPO receptor, which has a beautiful twofold symmetry-it was argued that this is the active state of the receptor. Activating the EPO receptor with EPO induces an almost instantaneous shutdown mechanism to sharply curtail any proliferative signal transduction, and thus, my hypotheses lead to the conclusion that the Amgen co-crystal is actually the state after receptor downregulation and thus an off-state. To put these hypotheses to the test, my computational method of Simulated Annealing of Chemical Potential was run using the co-crystal created at RWJ, which is the receptor trapped in a partial agonist state. The simulations predicted a previously unknown high affinity binding site at the pivot point where the two halves of the dimeric receptor meet, and detailed analysis of the fragment patterns led to the prediction of a molecule less than 300 MW that is basically twofold symmetric with a chiral center on one side and not the other. Thus, to the degree that computer simulations can be taken seriously, these results support my hypotheses on small molecule receptor activation. When this small molecule was synthesized and tested it indeed induced human hematopoietic stems cells to become red blood cells. When the predicted chiral center of this molecule was removed eliminating its one asymmetric feature, the resulting molecule was an antagonist-it could potently displace hot EPO but could no longer induce stem cell proliferation and differentiation. These results provided strong support for my theories on how to create potent small molecule EPO agonists and were used to launch the new company Locus Pharmaceuticals. These molecules, however, required significant chemical changes in order to make them stable in other in vitro assays and to be in vivo active, but these alterations had to be done in a way that maintained the symmetry-asymmetry considerations that led to the creation of an in vitro active molecule. The combination of changing functional grou

  7. Properties of water Polar molecule

    E-print Network

    Cochran-Stafira, D. Liane

    1 Water · Properties of water ­ Polar molecule · Hydrogen bonds with other water molecules, as a solid (ice) or as a gas (water vapor). · Water molecules are attracted to each other, creating hydrogen properties. Cohesion · Water molecules stick to each other. · The attraction between the water molecules

  8. Observational tests of Baryon symmetric cosmology

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1982-01-01

    Observational evidence for Baryon symmetric (matter/antimatter) cosmology and future observational tests are reviewed. The most significant consequences of Baryon symmetric cosmology lie in the prediction of an observable cosmic background of gamma radiation from the decay of pi(0)-mesons produced in nucleon-antinucleon annihilations. Equations for the prediction of the amma ray background spectrum for the case of high redshifts are presented. The theoretical and observational plots of the background spectrum are shown to be in good agreement. Measurement of cosmic ray antiprotons and the use of high energy neutrino astronomy to look for antimatter elsewhere in the universe are also addressed.

  9. CPT-symmetric discrete square well

    E-print Network

    Znojil, Miloslav

    2010-01-01

    A new version of an elementary PT-symmetric square well quantum model is proposed in which a certain Hermiticity-violating end-point interaction leaves the spectrum real in a large domain of couplings $\\lambda\\in (-1,1)$. Within this interval we employ the usual coupling-independent operator P of parity and construct, in a systematic Runge-Kutta discrete approximation, a coupling-dependent operator of charge C which enables us to classify our P-asymmetric model as CPT-symmetric or, equivalently, hiddenly Hermitian alias cryptohermitian.

  10. Influence of initial conditions in symmetric games

    NASA Astrophysics Data System (ADS)

    Balakrishnan, S.

    2014-12-01

    It is known that quantum game is characterized by the payoff matrix as well as initial states of the quantum objects used as carriers of information in a game. Further, the initial conditions of the quantum states influence the strategies adopted by the quantum players. In this paper, we identify the necessary condition on the initial states of quantum objects for converting symmetric games into potential games, in which the players acquire the same payoff matrix. The necessary condition to preserve the symmetric type and potential type of the game is found to be the same. The present work emphasizes the influence of the initial states in the quantization of games.

  11. High order WKB prediction of the energy splitting in the symmetric double well potential

    E-print Network

    Marko Robnik; Luca Salasnich; Marko Vranicar

    2000-03-24

    The accuracy of the WKB approximation when predicting the energy splitting of bound states in a double well potential is the main subject of this paper. The splitting of almost degenerate energy levels below the top of the barrier results from the tunneling and is thus supposed to be exponentially small. By using the standard WKB quantization we deduce an analytical formula for the energy splitting, which is the usual Landau formula with additional quantum corrections. We also examine the accuracy of our and Landau formula numerically for the case of the symmetric double well quartic potential.

  12. Testing for Life's Molecules

    NSDL National Science Digital Library

    2012-09-28

    In this activity, learners conduct tests for proteins, glucose, and starch. At the beginning of the activity, learners choose three items to test: one known to be “never alive," one known to be “once was alive,” and one mystery item. In addition, each station includes a positive control. By the end of the experiment, learners should be familiar with some of the major organic molecules and should recognize that living things, and substances derived from them, are made of organic molecules. Use this activity to bring in topics surrounding nutrition, health, and digestion--since our bodies are made up of organic molecules, we need each of these molecules as nutrients in our food.

  13. Of Molecules and Models.

    ERIC Educational Resources Information Center

    Brinner, Bonnie

    1992-01-01

    Presents an activity in which models help students visualize both the DNA process and transcription. After constructing DNA, RNA messenger, and RNA transfer molecules; students model cells, protein synthesis, codons, and RNA movement. (MDH)

  14. Properties of the Top Quark

    SciTech Connect

    Wicke, Daniel; /Wuppertal U., Dept. Math.

    2009-08-01

    The aim of particle physics is the understanding of elementary particles and their interactions. The current theory of elementary particle physics, the Standard Model, contains twelve different types of fermions which (neglecting gravity) interact through the gauge bosons of three forces. In addition a scalar particle, the Higgs boson, is needed for theoretical consistency. These few building blocks explain all experimental results found in the context of particle physics, so far. Nevertheless, it is believed that the Standard Model is only an approximation to a more complete theory. First of all the fourth known force, gravity, has withstood all attempts to be included until now. Furthermore, the Standard Model describes several features of the elementary particles like the existence of three families of fermions or the quantisation of charges, but does not explain these properties from underlying principles. Finally, the lightness of the Higgs boson needed to explain the symmetry breaking is difficult to maintain in the presence of expected corrections from gravity at high scales. This is the so called hierarchy problem. In addition astrophysical results indicate that the universe consists only to a very small fraction of matter described by the Standard Model. Large fractions of dark energy and dark matter are needed to describe the observations. Both do not have any correspondence in the Standard Model. Also the very small asymmetry between matter and anti-matter that results in the observed universe built of matter (and not of anti-matter) cannot be explained until now. It is thus an important task of experimental particle physics to test the predictions of the Standard Model to the best possible accuracy and to search for deviations pointing to necessary extensions or modifications of our current theoretical understanding. The top quark was predicted to exist by the Standard Model as the partner of the bottom quark. It was first observed in 1995 by the Tevatron experiments CDF and D0 and was the last of the quarks to be discovered. As the partner of the bottom quark the top quark is expected to have quantum numbers identical to that of the other known up-type quarks. Only the mass is a free parameter. We now know that it is more than 30 times heavier than the next heaviest quark, the bottom quark. Thus, within the Standard Model all production and decay properties are fully defined. Having the complete set of quarks further allows to verify constraints that the Standard Model puts on the sum of all quarks or particles. This alone is reason enough to experimentally study the top quark properties. The high value of the top quark mass and its closeness to the electroweak scale has inspired people to speculate that the top quark could have a special role in the electroweak symmetry breaking. Confirming the expected properties of the top quark experimentally establishes the top quark as we expect it to be. Any deviation from the expectations gives hints to new physics that may help to solve the outstanding questions. In this review the recent results on top quark properties obtained by the Tevatron experiments CDF and D0 are summarized. At the advent of the LHC special emphasis is given to the basic measurement methods and the dominating systematic uncertainties. After a short introduction to the Standard Model and the experimental environment in the remainder of this chapter, Chapter 2 describes the current status of top quark mass measurements. Then measurments of interaction properties are described in Chapter 3. Finally, Chapter 4 deals with analyses that consider hypothetical particles beyond the Standard Model in the observed events.

  15. Positron binding to molecules

    NASA Astrophysics Data System (ADS)

    Surko, C. M.; Danielson, J. R.; Gosselin, J. J.

    2010-03-01

    ˜ Positron annihilation on molecules as a function of incident positron energy exhibit vibrational Feshbach resonances (VFR).ootnotetextJ. A. Young and C. M. Surko, Phys. Rev. A 77, 052704 and 78, 032702 (2008). The energy differences between the vibrational modes and the VFR provide a measure of the positron-molecule binding energy, ?b. Measurements of ?b for 30 molecules are now available from this procedure and from comparison with theoretical spectra in the case of very small binding energies.^2 The dependence of ?b on molecular parameters can be expressed as ?b= 12.4(?+ 1.6?+ 2.4N?- 5.6) [meV], where ? is the molecular dipole polarizability, ? is the permanent dipole moment, and N? is the number of ? bonds in aromatic molecules.ootnotetextJ. R. Danielson, J. A. Young, and C. M. Surko, J. Phys. B 42, 235203 (2009). Insights into chemical trends from this analysis will be discussed. A key outstanding goal is to measure ?b for molecules that are sufficiently small and simple that ?b can be calculated theoretically. The empirical formula is used to identify candidate molecules. New measurements of ?b for CS2 (predicted ?b40 meV) will be discussed.

  16. Top-bottom doublet in the sphaleron background

    E-print Network

    J. M. Moreno; D. H. Oaknin; M. Quirós

    1995-08-30

    We consider the top-bottom doublet in the background of the sphaleron for the realistic case of large non-degeneracy of fermion masses, in particular $m_b=5$ GeV and $m_t=175$ GeV. We propose an axially symmetric $(r,\\theta)$-dependent ansatz for fermion fields and investigate the effects of the non-degeneracy on them. The exact solution is described, with an error less than 0.01\\%, by a set of ten radial functions. We also propose an approximate solution, in the $m_b/m_t\\rightarrow 0$ limit, with an error ${\\cal O}(m_b/m_t)$. We have found that the effects of non-degeneracy provide a $\\theta$-dependence typically $\\sim 10\\%$.

  17. Top quark studies at hadron colliders

    SciTech Connect

    Sinervo, P.K. [Univ. of Toronto, Ontario (Canada)

    1997-01-01

    The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag b quark jets in candidate events. The most recent measurements of top quark properties by the CDF and DO Collaborations are reviewed, including the top quark cross section, mass, branching fractions, and production properties. Future top quark studies at hadron colliders are discussed, and predictions for event yields and uncertainties in the measurements of top quark properties are presented.

  18. Top quark studies at hadron colliders

    SciTech Connect

    Sinervo, P.K. [Toronto Univ., ON (Canada). Dept. of Physics; CDF Collaboration

    1996-08-01

    The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag {ital b} quark jets in candidate events. The most recent measurements of top quark properties by the CDF and D{null} collaborations are reviewed, including the top quark cross section, mass, branching fractions and production properties. Future top quark studies at hadron colliders are discussed, and predictions for event yields and uncertainties in the measurements of top quark properties are presented.

  19. Supramolecular Host-Guest Chemistry of Heterocyclic V-Shaped Molecules

    NASA Astrophysics Data System (ADS)

    Bishop, Roger

    The host-guest inclusion properties of heterocyclic molecules that utilise C 2-symmetric V-shaped building blocks in their construction are reviewed. Such compounds are classified here according to the molecular structures of these building blocks. Salient features of the crystal structures of the resulting inclusion compounds are described and the f unctions of their key supramolecular synthons are analysed. Concepts underpinning the deliberate design and synthesis of new host molecules of this type are explained and then put into practice.

  20. Platonic Beasts: Spherically Symmetric Multilimbed Robots

    E-print Network

    Pai, Dinesh

    Platonic Beasts: Spherically Symmetric Multilimbed Robots Dinesh K. Pai Roderick A. Barman Scott K. Ralph Department of Computer Science University of British Columbia Vancouver, B.C. V6T 1Z4, Canada {pai beasts." A robot in this family is kinematically equivalent to a sym- metric polyhedron, such as one

  1. NonceBased Symmetric Encryption Phillip Rogaway

    E-print Network

    Rogaway, Phillip

    Nonce­Based Symmetric Encryption Phillip Rogaway Dept. of Computer Science, University encryption schemes are usually formalized so as to make the encryption operation a probabilistic or state­dependent func­ tion E of the message M and the key K: the user supplies M and K and the encryption process does

  2. Ch.19 Symmetric Encryption and Message Confidentiality

    E-print Network

    Dong, Yingfei

    1 1 Ch.19 Symmetric Encryption and Message Confidentiality · HW 9 and 10: upto this Wen · Next week: Ch.20 Public key Crypto · Conventional Encryption Principles · Conventional Encryption Algorithms: DES, AES · Cipher Block Modes of Operation: Block vs. stream · Location of Encryption Devices · Key

  3. Cylindrically symmetric solutions in conformal gravity

    SciTech Connect

    Brihaye, Y. [Physique Theorique et Mathematiques, Universite de Mons, Place du Parc, B-7000 Mons (Belgium); Verbin, Y. [Department of Natural Sciences, Open University of Israel, Raanana 43107 (Israel)

    2010-06-15

    Cylindrically symmetric solutions in conformal gravity are investigated and several new solutions are presented and discussed, among them a family of vacuum solutions, generalizations of the Melvin solution, and cosmic strings of the Abelian Higgs model. The Melvin-like solutions have finite energy per unit length, while the stringlike solutions do not.

  4. Irreducible complexity of iterated symmetric bimodal maps

    Microsoft Academic Search

    J. P. Lampreia; R. Severino; J. Sousa Ramos

    2004-01-01

    We introduce a tree structure for the iterates of symmetric bimodal maps and identify a subset which we prove to be isomorphic to the family of unimodal maps. This subset is used as a second factor for a $\\\\ast $-product that we define in the space of bimodal kneading sequences. Finally, we give some properties for this product and study

  5. Amplituhedron cells and Stanley symmetric functions

    E-print Network

    Thomas Lam

    2014-09-19

    The amplituhedron was recently introduced in the study of scattering amplitudes in $N=4$ super Yang-Mills. We compute the cohomology class of a tree amplituhedron subvariety of the Grassmannian to be the truncation of an affine Stanley symmetric function.

  6. Spherically symmetric monopoles in noncommutative space

    E-print Network

    E. F. Moreno

    2005-06-16

    We construct a spherically symmetric noncommutative space in three dimensions by foliating the space with concentric fuzzy spheres. We show how to construct a gauge theory in this space and in particular we derive the noncommutative version of a Yang-Mills-Higgs theory. We find numerical monopole solutions of the equations of motion.

  7. 1 Kastelyn's Theorem and Noneven Symmetric Digraphs*

    E-print Network

    Lim, Chjan C.

    's Theorem and Noneven Symmetric Digraphs* By Chjan C. Lim e-mail: limc@rpi.edu Abstract A noneven digraph in no even cycles. A directed cycle in a weig* *hted digraph is even if the sum of weights of its arcs

  8. Vertex-symmetric Digraphs with Small Diameter

    Microsoft Academic Search

    Francesc Comellas; Miguel Angel Fiol

    1995-01-01

    There is increasing interest in the design of dense vertex symmetric graphs and digraphs as models of interconnection networks for implementing parallelism. In these systems many nodes are connected with relatively few links and short paths between them and each node may execute, without modifications, the same com- munication software. In this paper we give new families of dense vertex

  9. Symmetric space description of carbon nanotubes

    E-print Network

    M. Caselle; U. Magnea

    2006-01-10

    Using an innovative technique arising from the theory of symmetric spaces, we obtain an approximate analytic solution of the Dorokhov-Mello-Pereyra-Kumar (DMPK) equation in the insulating regime of a metallic carbon nanotube with symplectic symmetry and an odd number of conducting channels. This symmetry class is characterized by the presence of a perfectly conducting channel in the limit of infinite length of the nanotube. The derivation of the DMPK equation for this system has recently been performed by Takane, who also obtained the average conductance both analytically and numerically. Using the Jacobian corresponding to the transformation to radial coordinates and the parameterization of the transfer matrix given by Takane, we identify the ensemble of transfer matrices as the symmetric space of negative curvature SO^*(4m+2)/[SU(2m+1)xU(1)] belonging to the DIII-odd Cartan class. We rederive the leading-order correction to the conductance of the perfectly conducting channel and its variance Var(log(delta g)). Our results are in complete agreement with Takane's. In addition, our approach based on the mapping to a symmetric space enables us to obtain new universal quantities: a universal group theoretical expression for the ratio Var(log(delta g)/ and as a byproduct, a novel expression for the localization length for the most general case of a symmetric space with BC_m root system, in which all three types of roots are present.

  10. Support for Symmetric Shadow Memory in Multiprocessors

    E-print Network

    Gupta, Rajiv

    (OMI) is then accompanied by additional shadow memory instructions (SMIs) that manipulate the meta data associated with the memory location. Often the SMIs associated with OMIs are symmetric, in that, origi- nal implementations need thread serialization to ensure that OMIs and SMIs are exe- cuted atomically [12]. Naturally

  11. Spherically symmetric monopoles in noncommutative space

    SciTech Connect

    Moreno, E.F. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina) and Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315 (United States)

    2005-08-15

    We construct a spherically symmetric noncommutative space in three dimensions by foliating the space with concentric fuzzy spheres. We show how to construct a gauge theory in this space, and, in particular, we derive the noncommutative version of a Yang-Mills-Higgs theory. We find numerical monopole solutions of the equations of motion.

  12. Reciprocal Symmetric and Origin of Quantum Statistics

    E-print Network

    Mushfiq Ahmad

    2007-03-21

    Boltzmann's differential equation is replaced by the corresponding reciprocal symmetric finite difference equation. Finite difference translates discreteness of energy. Boltzmann's function, then, splits into two reciprocally related functions. One of them gives Planck's radiation relation and the other one gives the corresponding Fermi-Dirac relation.

  13. Resonances for Symmetric Two-Barrier Potentials

    ERIC Educational Resources Information Center

    Fernandez, Francisco M.

    2011-01-01

    We describe a method for the accurate calculation of bound-state and resonance energies for one-dimensional potentials. We calculate the shape resonances for symmetric two-barrier potentials and compare them with those coming from the Siegert approximation, the complex scaling method and the box-stabilization method. A comparison of the…

  14. Unidirectional nonlinear PT-symmetric optical structures

    SciTech Connect

    Ramezani, Hamidreza [Department of Physics, Wesleyan University, Middletown, Connecticut 06459 (United States); Kottos, Tsampikos [Department of Physics, Wesleyan University, Middletown, Connecticut 06459 (United States); Max-Planck-Institute for Dynamics and Self-Organization, D-37073 Goettingen (Germany); El-Ganainy, Ramy; Christodoulides, Demetrios N. [College of Optics and Photonics-CREOL, University of Central Florida, Orlando, Florida 32816 (United States)

    2010-10-15

    We show that nonlinear optical structures involving a balanced gain-loss profile can act as unidirectional optical valves. This is made possible by exploiting the interplay between the fundamental symmetries of parity (P) and time (T), with optical nonlinear effects. This unidirectional dynamics is specifically demonstrated for the case of an integrable PT-symmetric nonlinear system.

  15. Laws of Trigonometry in Symmetric Spaces

    Microsoft Academic Search

    Helmer Aslaksen; Hsueh-Ling Huynh

    This paper consists of two parts. In the flrst part, we reformulate the work of E. Leuzinger on trigonometry in noncompact symmetric spaces. In the second part, we outline an alternative method using invariants of the isotropy group representation. Appropriately formulated, these methods apply to both compact and noncompact sym- metric spaces. This work is contained in the Ph.D. dissertation

  16. Axially symmetric potentials in the oscillator representation

    Microsoft Academic Search

    M. Dineykhan

    1997-01-01

    The Wick-ordering method called the Oscillator Representation in the nonrelativistic Schrödinger equation is proposed to calculate the energy spectrum for axially symmetric potentials allowing the existence of a bound state. In particular, the method is applied to calculate the energy spectrum of (2s) states of a hydrogen atom in a uniform magnetic field of an arbitrary strength. In the perturbation

  17. PT -Symmetric Quantum Electrodynamics Carl M. Bender

    E-print Network

    Milton, Kim

    PT -Symmetric Quantum Electrodynamics Carl M. Bender Theoretical Physics, Blackett Laboratory, OK 73019, USA (Dated: January 21, 2005) Abstract The Hamiltonian for quantum electrodynamics becomes is self-adjoint. In this paper the corresponding C operator for non- Hermitian quantum electrodynamics

  18. A Concrete Security Treatment of Symmetric Encryption

    Microsoft Academic Search

    Mihir Bellare; Anand Desai; E. Jokipii; Phillip Rogaway

    1997-01-01

    We study notions and schemes for symmetric (ie. private key) encryption in a concrete security framework. We give four different notions of security against chosen plaintext attack and analyze the concrete complexity of reductions among them, providing both upper and lower bounds, and obtaining tight relations. In this way we classify notions (even though polynomially reducible to each other) as

  19. Extending additivity from symmetric to asymmetric channels

    E-print Network

    Motohisa Fukuda

    2005-08-14

    We prove a lemma which allows one to extend results about the additivity of the minimal output entropy from highly symmetric channels to a much larger class. A similar result holds for the maximal output $p$-norm. Examples are given showing its use in a variety of situations. In particular, we prove the additivity and the multiplicativity for the shifted depolarising channel.

  20. Numerical evaluation of a symmetric potential function

    Microsoft Academic Search

    Lori A. Carmack

    1998-01-01

    We discuss the numerical evaluation of a symmetric potential func- tion which arises naturally in applications. We present a method designed to accurately and eciently compute this integral, and compare the performance of this method with two other popular techniques. This method requires con- siderably fewer function evaluations than all other techniques we tested, and is applicable to any integral

  1. TOPS electronic warfare channelizer program

    NASA Astrophysics Data System (ADS)

    Alexander, Edward M.

    1992-07-01

    The TOPS Electronic Warfare channelizer program is an effort being conducted under the DARPA sponsored Transition of Optical Processing into Systems (TOPS) initiative. The objective is a high probability-of-intercept radar receiver for signals in dense environments. Channelization is the preferred receiver approach in interfering signal environments because it instantly sorts time coincident pulse signals. Channelization is performed optically, using acousto-optical techniques, since optics offers size, weight, power and cost advantages. This program is a three year channelizer development effort. Once developed, the receiver will be tested integrated with an existing electronic warfare system. The paper will review the program background. The electronic, mechanical and optical requirements will be addressed. The critical technical issues impacting this program will be analyzed.

  2. Scalar top study: Detector optimization

    SciTech Connect

    Milstene, C.; /Fermilab; Sopczak, A.; /Lancaster U.

    2006-09-01

    A vertex detector concept of the Linear Collider Flavor Identification (LCFI) collaboration, which studies pixel detectors for heavy quark flavor identification, has been implemented in simulations for c-quark tagging in scalar top studies. The production and decay of scalar top quarks (stops) is particularly interesting for the development of the vertex detector as only two c-quarks and missing energy (from undetected neutralinos) are produced for light stops. Previous studies investigated the vertex detector design in scenarios with large mass differences between stop and neutralino, corresponding to large visible energy in the detector. In this study we investigate the tagging performance dependence on the vertex detector design in a scenario with small visible energy for the International Linear Collider (ILC).

  3. Attitude propulsion technology for TOPS

    NASA Technical Reports Server (NTRS)

    Moynihan, P. I.

    1972-01-01

    The thermoelectric outer planet spacecraft (TOPS) attitude propulsion subsystem (APS) effort is discussed. It includes the tradeoff rationale that went into the selection of an anhydrous hydrazine baseline system, followed by a discussion of the 0.22 N thruster and its integration into a portable, self-contained propulsion module that was designed, developed, and man rated to support the TOPS single-axis attitude control tests. The results of a cold-start feasibility demonstration with a modified thruster are presented. A description of three types of 0.44 thrusters that were procured for in-house evaluation is included along with the results of the test program. This is followed by a description of the APS feed system components, their evaluations, and a discussion of an evaluation of elastomeric material for valve seat seals. A list of new technology items which will be of value for application to future systems of this type is included.

  4. Thermoelectric Outer Planets Spacecraft (TOPS)

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The research and advanced development work is reported on a ballistic-mode, outer planet spacecraft using radioisotope thermoelectric generator (RTG) power. The Thermoelectric Outer Planet Spacecraft (TOPS) project was established to provide the advanced systems technology that would allow the realistic estimates of performance, cost, reliability, and scheduling that are required for an actual flight mission. A system design of the complete RTG-powered outer planet spacecraft was made; major technical innovations of certain hardware elements were designed, developed, and tested; and reliability and quality assurance concepts were developed for long-life requirements. At the conclusion of its active phase, the TOPS Project reached its principal objectives: a development and experience base was established for project definition, and for estimating cost, performance, and reliability; an understanding of system and subsystem capabilities for successful outer planets missions was achieved. The system design answered long-life requirements with massive redundancy, controlled by on-board analysis of spacecraft performance data.

  5. Discrete energy transport in collagen molecules

    NASA Astrophysics Data System (ADS)

    Alain, Mvogo; Germain, H. Ben-Bolie; Timoléon, C. Kofané

    2014-09-01

    The modulational instability in the three coupled ?-polypeptide chains of a collagen molecule is investigated. Choosing symmetric and asymmetric solutions, and applying the so-called rotating-wave approximation, we describe the dynamics of the system by the discrete nonlinear Schrödinger (DNLS) equation. The linear stability analysis of the continuous wave solution is performed. The numerical simulations show the generation of trains of solitonic structures in the lattice with increasing amplitude as time progresses. The effect of damping and noise forces of the physiological temperature (T = 300 K) introduces an erratic behavior to the formed patterns, reinforcing the idea that the energy used in metabolic processes is confined to specific regions for efficiency.

  6. Orbits in the H2O molecule

    E-print Network

    K. Efstathiou; G. Contopoulos

    2001-02-07

    We study the forms of the orbits in a symmetric configuration of a realistic model of the H2O molecule with particular emphasis on the periodic orbits. We use an appropriate Poincar\\'e surface of section (PSS) and study the distribution of the orbits on this PSS for various energies. We find both ordered and chaotic orbits. The proportion of ordered orbits is almost 100% for small energies, but decreases abruptly beyond a critical energy. When the energy exceeds the escape energy there are still non-escaping orbits around stable periodic orbits. We study in detail the forms of the various periodic orbits, and their connections, by providing appropriate stability and bifurcation diagrams.

  7. Evolution of Chemical and Sensory Properties during Aging of Top-Fermented Beer

    Microsoft Academic Search

    Bart Vanderhaegen; Hedwig Neven; Stefan Coghe; Kevin J. Verstrepen; Hubert Verachtert; Guy Derdelinckx

    2003-01-01

    The aging and consequent changes in flavor molecules of a top-fermented beer were studied. Different aging conditions were imposed on freshly bottled beer. After 6 months of aging, the concentration changes were recorded for acetate esters, ethyl esters, carbonyls, Maillard compounds, dioxolanes, and furanic ethers. For some flavor compounds, the changes with time of storage were monitored at different temperatures,

  8. Student Top Ten Wish List

    NSDL National Science Digital Library

    DeafTEC provides this resource which covers the top ten things deaf and hard of hearing students would like their teachers to do. The handout includes ideas and suggestions to facilitate a more accessible classroom environment for deaf and hard of hearing students. Some of the items on the list include: making PowerPoint and lecture notes available to deaf students before class beings, treating all students equally, to be aware of "process time," and several others. 

  9. Cloud Top Scanning radiometer (CTS)

    NASA Technical Reports Server (NTRS)

    1978-01-01

    A scanning radiometer to be used for measuring cloud radiances in each of three spectral regions is described. Significant features incorporated in the Cloud Top Scanner design are: (1) flexibility and growth potential through use of easily replaceable modular detectors and filters; (2) full aperture, multilevel inflight calibration; (3) inherent channel registration through employment of a single shared field stop; and (4) radiometric sensitivity margin in a compact optical design through use of Honeywell developed (Hg,Cd)Te detectors and preamplifiers.

  10. Observation of the top quark

    SciTech Connect

    Greenlee, H.; D0 Collaboration

    1995-05-01

    The DO collaboration reports on a search for the Standard Model top quark in p{bar p} collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron, with an integrated luminosity of approximately 50 pb{sup {minus}1}. We have searched for t{bar t} production in the dilepton and single-lepton decay channels, with and without tagging of b quark jets. We observe 17 events with an expected background of 3.8 {plus_minus} 0.6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2 {times} 10{sup {minus}6} (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measure its mass to be 199{sub {minus}21}{sup +19} (stat.) {plus_minus}22 (syst.) GeV/c{sup 2} and its production cross section to be 6.4 {plus_minus} 2.2 pb.

  11. Observation of the Top Quark

    SciTech Connect

    Abachi, S.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adam, I.; Adams, D.L.; Adams, M.; Ahn, S.; Aihara, H.; Aihara, H.; Alitti, J.; Alvarez, G.; Alves, G.A.; Amidi, E.; Amos, N.; Anderson, E.W.; Aronson, S.H.; Astur, R.; Avery, R.E.; Balamurali, V.; Balderston, J.; Baldin, B.; Bantly, J.; Bartlett, J.F.; Bazizi, K.; Bendich, J.; Beri, S.B.; Bertram, I.; Bezzubov, V.A.; Bhat, P.C.; Bhatnagar, V.; Bhattacharjee, M.; Bischoff, A.; Biswas, N.; Blazey, G.; Blessing, S.; Boehnlein, A.; Bojko, N.I.; Borcherding, F.; Borders, J.; Boswell, C.; Brandt, A.; Brock, R.; Bross, A.; Buchholz, D.; Burtovoi, V.S.; Butler, J.M.; Casey, D.; Castilla-Valdez, H.; Chakraborty, D.; Chang, S.; Chekulaev, S.V.; Chen, L.; Chen, W.; Chevalier, L.; Chopra, S.; Choudhary, B.C.; Christenson, J.H.; Chung, M.; Claes, D.; Clark, A.R.; Cobau, W.G.; Cochran, J.; Cooper, W.E.; Cretsinger, C.; Cullen-Vidal, D.; Cummings, M.; Cutts, D.; Dahl, O.I.; De, K.; Demarteau, M.; Demina, R.; Denisenko, K.; Denisenko, N.; Denisov, D.; Denisov, S.P.; Dharmaratna, W.; Diehl, H.T.; Diesburg, M.; Di Loreto, G.; Dixon, R.; Draper, P.; Drinkard, J.; Ducros, Y.; Dugad, S.R.; Durston-Johnson, S.; Edmunds, D.; Efimov, A.O.; Ellison, J.; Elvira, V.D.; Engelmann, R.; Eno, S.; Eppley, G.; Ermolov, P.; Eroshin, O.V.; Evdokimov, V.N.; Fahey, S.; Fahland, T.; Fatyga, M.; Fatyga, M.K.; Featherly, J.; Feher, S.; Fein, D.; Ferbel, T.; Finocchiaro, G.; Fisk, H.E.; Fisyak, Y.; Flattum, E.; Forden, G.E.; Fortner, M.; Frame, K.C.; Franzini, P.; Fredriksen, S.; Fuess, S.; Galjaev, A.N.; Gallas, E.; Gao, C.S.; Gao, S.; Geld, T.L.; Genik, R.J. II; Genser, K.; Gerber, C.E.; Gibbard, B.; Glaubman, M.; Glebov, V.; Glenn, S.; Glicenstein, J.F.; Gobbi, B.; Goforth, M.; Goldschmidt, A.; Gomez, B.; Goncharov, P.I.; Gordon, H.; Goss, L.T.; Graf, N.; Grannis, P.D.; Green, D.R.; Green, J.; Greenlee, H.; Griffin, G.; Grossman, N.; Grudberg, P.; Gruenendahl, S.; Guida, J.A.; Guida, J.M.; Guryn, W.; Gurzhiev, S.N.; Gutnikov, Y.E.; (D0 Collaboration)

    1995-04-03

    The D0 Collaboration reports on a search for the standard model top quark in {ital p{bar p}} collisions at {radical}{ital s}=1.8TeV at the Fermilab Tevatron with an integrated luminosity of approximately 50pb{sup {minus}1}. We have searched for {ital t{bar t}} production in the dilepton and single-lepton decay channels with and without tagging of {ital b}-quark jets. We observed 17 events with an expected background of 3.8{plus_minus}0.6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2{times}10{sup {minus}6} (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measured its mass to be 199{sub {minus}21}{sup +19} (stat) {plus_minus}22 (syst) GeV/{ital c}{sup 2} and its production cross section to be 6.4{plus_minus}2.2pb.

  12. Ion-Molecule Reactions

    NASA Astrophysics Data System (ADS)

    Farrar, James

    The observation of ion-molecule reactions has a history that goes back to the beginning of the twentieth century, when J. J. Thomson discovered that operating his positive ray parabola apparatus in a hydrogen atmosphere produced signals at a mass to charge ratio of 3, which he correctly attributed to the species H3 [67.1]. Later studies showed that this species was produced by a reaction between the primary ionization product H2 + and molecular hydrogen. Most ion-molecule reactions proceed without an activation barrier and their cross sections are governed by the long range attractive potential of the approaching reactants (Sect. 64.2.4). Reaction rates based on long range potential capture models [67.2] predict rates in excess of 10-9 cm3molecule-1s-1, corresponding to thermal energy cross sections (Sect. 47.1.7) of 10-16-10-15 cm2. The importance of ion-molecule reactions in such widely diverse areas as planetary atmospheres, (Sect. 84.1), electrical discharges and plasmas (Sect. 87.1.4), particularly in semiconductor processing, in the formation of molecules in interstellar space (Chapt. 82), and in flames and combustion systems (Sect. 88.1), has borne out that prediction. This chapter discusses applications of single-collision scattering methods to the study of reactive collision dynamics of ionic species with neutral partners.

  13. Top Ten Homework Tips (For Parents)

    MedlinePLUS

    ... Lessons? Visit KidsHealth in the Classroom What Other Parents Are Reading Measles: What to Know Vaccines: FAQs ... What to Expect Top 10 Homework Tips KidsHealth > Parents > School & Family Life > Learning & Education > Top 10 Homework ...

  14. Methane molecule over the defected and rippled graphene sheet

    NASA Astrophysics Data System (ADS)

    Shayeganfar, F.; Neek-Amal, M.

    2012-08-01

    Adsorption of a methane molecule (CH4) onto a defected and rippled graphene sheet is studied using ab initio and molecular mechanics calculations. The optimal adsorption position and orientation of this molecule on the graphene surface (motivated by the recent realization of graphene sensors to detect individual gas molecules) is determined and the adsorption energies are calculated. In light of the density of states, we used the SIESTA code. It is found that (i) classical force field yields adsorption energy comparable with experimental result and ab initio calculation; (ii) the periodic nature of the van der Waals potential energy stored between methane and perfect sheet is altered due to the insertion vacancies and sinusoidal ripples; (iii) the van der Waals potential energy is found to be sensitive to the presence of the vacancies and the ripples so that the added molecule avoids to be around vacant cites and on top of the peaks.

  15. Evidence for production of single top quarks

    Microsoft Academic Search

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

    2008-01-01

    We present first evidence for the production of single top quarks in the D0 detector at the Fermilab Tevatron p pmacr collider. The standard model predicts that the electroweak interaction can produce a top quark together with an antibottom quark or light quark, without the antiparticle top-quark partner that is always produced from strong-coupling processes. Top quarks were first observed

  16. Heavy flavour physics from top to bottom

    SciTech Connect

    Paulini, M. [Lawrence Berkeley National Lab., CA (United States); CDF and D0 Collaboration

    1998-02-01

    We review the status of heavy flavour physics at the Fermilab Tevatron collider by summarizing recent top quark and B physics results from CDF and D0. In particular we discuss the measurement of the top quark mass and top production cross section as well as B meson lifetimes and time dependent B{anti B} mixing results. An outlook of perspectives for top and B physics in Run II starting in 1999 is also given.

  17. Cloud-top parameters - A hail indicator

    NASA Technical Reports Server (NTRS)

    Pearl, E. W.; Shenk, W. E.; Skillman, W.

    1975-01-01

    Airborne photographic observations of four hail-producing storms are discussed. With the exception of one storm producing a tornadic event, the overshooting tops were nearly steady-state. The tops were consistently high and wide, reaching maximum heights within about 5 minutes of the initiation of hail. Measured updraft velocities in the turrets composing the overshooting top were 25 m/sec. The dimensions of the overshooting tops were sufficiently large to permit satellite observation.

  18. Collision-induced absorption in a highly symmetric molecule - SF6

    NASA Astrophysics Data System (ADS)

    Birnbaum, George; Sutter, Herbert

    The far-infrared absorption spectra of gaseous (298 K) and liquid (273 K, 233 K) SF6 obtained by Rosenberg and Birnbaum [1] are analysed in terms of recent theoretical developments. Analysis of the band shape in the gas and liquid phases indicates that hexadecapole-induced absorption accounts only for the low frequency portion of the collision-induced band. The major part of the absorption can be attributed to a much shorter range mechanism such as anisotropic overlap. The resulting induced dipole which varies very rapidly with intermolecular separation and is consistent with a (7-28) interaction energy gives a good description of the liquid spectra. Collision-induced absorption and depolarized light scattering in SF6 are compared. From a decomposition of the collision-induced gaseous spectrum, the value of the hexadecapolar energy, ?2/?9, is 2·7 × 10-24 J (0·20 K) which yields a value of the hexadecapole moment, ?, of 18 × 10-60 C m4 for ? = 0·468 nm.

  19. An Antibody Molecule

    NSDL National Science Digital Library

    Martin Raff

    1998-07-01

    An antibody molecule. (A) Schematic drawing of a typical antibody molecule. As indicated, this protein is Y-shaped and has two identical binding sites for its antigen, one on either arm of the 3Y.2 The protein is composed of four polypeptide chains (two identical heavy chains and two identical and smaller light chains) held together by disulfide bonds. Each chain is made up of several different domains, here shaded either blue or gray. The antigen-binding site is formed where a heavy chain variable domain (VH) and a light chain variable domain (VL) come close together. These are the domains that differ most in their sequence and structure in different antibodies. (B) Ribbon drawing of a light chain showing the parts of the VL domain most closely involved in binding to the antigen in red; these contribute half of the fingerlike loops that fold around each of the antigen molecules in (A).

  20. MOLECULES IN {eta} CARINAE

    SciTech Connect

    Loinard, Laurent; Menten, Karl M.; Guesten, Rolf [Max-Planck Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); Zapata, Luis A.; Rodriguez, Luis F. [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 3-72, 58090 Morelia, Michoacan (Mexico)

    2012-04-10

    We report the detection toward {eta} Carinae of six new molecules, CO, CN, HCO{sup +}, HCN, HNC, and N{sub 2}H{sup +}, and of two of their less abundant isotopic counterparts, {sup 13}CO and H{sup 13}CN. The line profiles are moderately broad ({approx}100 km s{sup -1}), indicating that the emission originates in the dense, possibly clumpy, central arcsecond of the Homunculus Nebula. Contrary to previous claims, CO and HCO{sup +} do not appear to be underabundant in {eta} Carinae. On the other hand, molecules containing nitrogen or the {sup 13}C isotope of carbon are overabundant by about one order of magnitude. This demonstrates that, together with the dust responsible for the dimming of {eta} Carinae following the Great Eruption, the molecules detected here must have formed in situ out of CNO-processed stellar material.

  1. Molecules on ice

    SciTech Connect

    Clary, D.C.

    1996-03-15

    The ozone hole that forms in the spring months over the Antarctic is thought to be produced through a network of chemical reactions catalyzed by the surfaces of ice crystals in polar stratospheric clouds (PSCs). A reaction between chlorine reservoir molecules, such as HCl + ClONO{sub 2} > HNO{sub 3} + Cl{sub 2}, is kinetically forbidden in the gas phase but proceeds quickly on the surface of ice and produces Cl{sub 2} molecules that are photodissociated by sunlight to yield the Cl atoms that destroy ozone. This destructive chain of events begins when HCl molecules stick to the ice crystals, and the mechanism for this crucial sticking process has been the subject of much debate. Recent work describes a mechanism that explains how HCl sticks to ice. This article goes on to detail research focusing surface reactions in stratospheric chemistry. 9 refs., 1 fig.

  2. Building bio-inspired artificial functional nanochannels: from symmetric to asymmetric modification.

    PubMed

    Hou, Xu; Zhang, Huacheng; Jiang, Lei

    2012-05-29

    Over millions of years, complex processes of intelligent control have evolved in nature. Learning from nature is a continuing theme in the development of smart materials and intelligent systems. For example, biological nanochannels, which are typically ion channels, play a very important role in basic biochemical processes in cells. Inspired by ion channels, in which the components are asymmetrically distributed between the membrane surfaces, the generation of biomimetic smart nanochannels is a broad and varied scientific research field. The design and development of new biomimetic channels includes the use of different shapes of channels, different stimuli-responsive molecules, and different symmetric/asymmetric modification methods. In this Minireview, we summarize recent developments in building functional nanochannels by applying various symmetric and asymmetric modifications. PMID:22505178

  3. Simulation of Top Oil Temperature for Transformers

    E-print Network

    Simulation of Top Oil Temperature for Transformers Masters Thesis and Final Project Report Power temperature accurately. There are several transformer models for predicting top-oil temperature. These include of Mines Georgia Tech · Illinois · Iowa State · Texas A&M · Washington State · Wisconsin Simulation of Top-Oil

  4. In Praise of Top-Down Leadership

    ERIC Educational Resources Information Center

    Dufour, Richard

    2007-01-01

    In the ongoing debate of the efficacy of top-down versus bottom-up strategies to improve school districts, top-down is clearly losing. Many district leaders are reluctant to champion improvement for fear of being labeled with the epithet "top-down leader," the unkindest cut of all. In this article, the author presents the change processes in three…

  5. Top quark physics expectations at the LHC

    E-print Network

    Andrei Gaponenko; for the ATLAS Collaboration; for the CMS Collaboration

    2008-10-22

    The top quark will be produced copiously at the LHC. This will make both detailed physics studies and the use of top quark decays for detector calibration possible. This talk reviews plans and prospects for top physics activities in the ATLAS and CMS experiments.

  6. Reverse Top-k Queries [DRAFT VERSION

    E-print Network

    Reverse Top-k Queries [DRAFT VERSION] Akrivi Vlachou # , Christos Doulkeridis # , Yannis Kotidis become essential for many applications that return to the user only the top-k objects based on the individual user's preferences. Top-k queries have been mainly studied from the perspective of the user

  7. Typechecking Top-Down XML Transformations

    E-print Network

    Martens, Wim

    Typechecking Top-Down XML Transformations Wim Martens, Frank Neven University of Limburg Typechecking Top-Down XML Transformations ­ p.1/24 #12;Overview Introduction Schema : Tree Languages Tree Top-Down XML Transformations ­ p.2/24 #12;Importance of Typechecking An example: Suppose

  8. 47 CFR 51.711 - Symmetrical reciprocal compensation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Symmetrical reciprocal compensation. 51.711 Section...FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON...INTERCONNECTION Reciprocal Compensation for Transport and...Symmetrical reciprocal compensation. (a) Rates...incumbent LEC, a state commission shall establish...

  9. Wiring up Single Molecules

    NSDL National Science Digital Library

    In recent years, circuit design has advanced to achieve extremely small feature sizes -- literally tens of millions of transistors can be integrated in a single chip. This progress has given rise to molecular electronics, the notion of creating electronic devices with single molecules as circuit elements. In this paper, the authors "discuss transistors, where electrons flow through discrete quantum states of a single molecule." Fabrication considerations are outlined, and the current-voltage responses of several such transistors that were fabricated by the authors are shown. The paper concludes by looking ahead to future possibilities of chemically-tailored transistors that could be designed with specific properties.

  10. Alphabetical Listing of Molecules

    NSDL National Science Digital Library

    This useful, straightforward site will help students understand the structure of molecules through visualization. It was created by W. F. Coleman, Professor of Chemistry at Wellesley College. Here, you will find several common substances including caffeine, penicillin, Viagra, and vitamin A, as well as a few more exotic ones. Using the Chime software, a free chemical structure visualization plug-in for Windows and Macintosh, each molecule isn't simply a static image. It can be rotated for a complete examination, reformatted, and saved in a variety of file formats. A download link for Chime is provided.

  11. DNA Molecule - Two Views

    NSDL National Science Digital Library

    Access Excellence

    2005-03-12

    The double helix of the DNA is shown along with details of how the bases, sugars and phosphates connect to form the structure of the molecule. DNA is a double-stranded molecule twisted into a helix (think of a spiral staircase). Each spiraling strand, comprised of a sugar-phosphate backbone and attached bases, is connected to a complementary strand by non-covalent hydrogen bonding between paired bases. The bases are adenine (A), thymine (T), cytosine (C) and guanine (G). A and T are connected by two hydrogen bonds. G and C are connected by three hydrogen bonds.

  12. Molecules in Motion

    NSDL National Science Digital Library

    In this learning assessment, students demonstrate understanding of the following concepts: solids, liquids and gases, changes of state, convection, and density. Students create a skit where the actors and actresses are molecules, and dramatize, through body motions, how the behavior of molecules results in the observable changes we see. A detailed scoring rubric is included with the resource. The investigation supports material presented in chapter 3 "What Heats the Earth's Interior?" in the textbook, Energy flow, part of Global System Science, an interdisciplinary course for high school students that emphasizes how scientists from a wide variety of fields work together to understand significant problems of global impact.

  13. Mighty Molecule Models

    NSDL National Science Digital Library

    Greg Rushton

    2008-01-01

    As part of the SMATHematics Project: The Wonder of Science, The Power of Mathematics--a collaborative partnership between Kennesaw State University and two local school districts, fifth graders had the opportunity to puzzle out chemical formulas of propane, methanol, and other important molecules. In addition, they explored properties that characterize certain molecules and then used their newly acquired knowledge of atoms' bonding requirements to help them build three-dimensional molecular models. The effort is succeeding--as you can see by the fifth-grade classroom experience described here.

  14. Matrix isolation ESR spectroscopy and magnetic anisotropy of D{sub 3h} symmetric septet trinitrenes

    SciTech Connect

    Misochko, Eugenii Ya.; Akimov, Alexander V.; Masitov, Artem A.; Korchagin, Denis V.; Aldoshin, Sergei M.; Chapyshev, Sergei V. [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432 (Russian Federation)

    2013-05-28

    The fine-structure (FS) parameters D of a series of D{sub 3h} symmetric septet trinitrenes were analyzed theoretically using density functional theory (DFT) calculations and compared with the experimental D values derived from ESR spectra. ESR studies show that D{sub 3h} symmetric septet 1,3,5-trichloro-2,4,6-trinitrenobenzene with D=-0.0957 cm{sup -1} and E= 0 cm{sup -1} is the major paramagnetic product of the photolysis of 1,3,5-triazido-2,4,6-trichlorobenzene in solid argon matrices at 15 K. Trinitrenes of this type display in the powder X-band ESR spectra intense Z{sub 1}-transition at very low magnetic fields, the position of which allows one to precisely calculate the parameter D of such molecules. Thus, our revision of the FS parameters of well-known 1,3,5-tricyano-2,4,6-trinitrenobenzene [E. Wasserman, K. Schueller, and W. A. Yager, Chem. Phys. Lett. 2, 259 (1968)] shows that this trinitrene has Double-Vertical-Line D Double-Vertical-Line = 0.092 cm{sup -1} and E= 0 cm{sup -1}. DFT calculations reveal that, unlike C{sub 2v} symmetric septet trinitrenes, D{sub 3h} symmetric trinitrenes have the same orientations of the spin-spin coupling tensor D-caret{sub SS} and the spin-orbit coupling tensor D-caret{sub SOC} and, as a result, have negative signs for both the D{sub SS} and D{sub SOC} values. The negative magnetic anisotropy of septet 2,4,6-trinitrenobenzenes is considerably strengthened on introduction of heavy atoms in the molecules, owing to an increase in contributions of various excitation states to the D{sub SOC} term.

  15. Parametric device for symmetrization of three-phase potentials

    Microsoft Academic Search

    A. K. Shidlovskii; A. D. Muzychenko; I. V. Mostoviak; A. P. Trofimenko

    1979-01-01

    The paper proposes a schematic design of a device for parametric symmetrization of three-phase potentials with simultaneous power supply from a three-phase network of single-phase and symmetric three-phase loads. The dependence of symmetric device parameters on the power transmission line impedance is computed, and it is shown that the effect of complete parametric symmetrization is not impaired by any changes

  16. Imaging of Single Molecule Diffusion

    Microsoft Academic Search

    Th. Schmidt; G. J. Schutz; W. Baumgartner; H. J. Gruber; H. Schindler

    1996-01-01

    In recent years observations at the level of individual atoms and molecules became possible by microscopy and spectroscopy. Imaging of single fluorescence molecules has been achieved but has so far been restricted to molecules in the immobile state. Here we provide methodology for visualization of the motion of individual fluorescent molecules. It is applied to imaging of the diffusional path

  17. Symmetrical factorization of the fast Fourier transform for efficient implementation

    Microsoft Academic Search

    H. K. Sim

    2004-01-01

    This paper shows a symmetrical decomposition of the Fast Fourier Transform (FFT) into stages such that butterflies of small radices can be applied efficiently. Due to symmetric, the bit reversal sorting is also symmetrical and allows semi in-place self-sorting to be carried out together with the butterfly processing at the middle stage. Furthermore, the mirroring effect due to the symmetry,

  18. DIRECTED CYCLIC HAMILTONIAN CYCLE SYSTEMS OF THE COMPLETE SYMMETRIC DIGRAPH

    E-print Network

    Morris, Joy

    DIRECTED CYCLIC HAMILTONIAN CYCLE SYSTEMS OF THE COMPLETE SYMMETRIC DIGRAPH HEATHER JORDON AND JOY symmetric digraph, K n, exist if and only if n 2 (mod 4) and n = 2p with p prime and 1. We also show that directed cyclic hamiltonian cycle systems of the complete symmetric digraph minus a set of n/2 vertex

  19. Elliptical symmetric distribution based maximal margin classification for hyperspectral imagery

    Microsoft Academic Search

    Lin He; Zhuliang Yu; Zhenghui Gu; Yuanqing Li

    2011-01-01

    It has been verified that hyperspectral data is statistically characterized by elliptical symmetric distribution. Accordingly, we introduce the ellipsoidal discriminant boundaries and present an elliptical symmetric distribution based maximal margin (ESD-MM) classifier for hypespectral classification. In this method, the characteristic of elliptical symmetric distribution (ESD) of hyperspectral data is combined with the maximal margin rule. This strategy enables the ESD-MM

  20. KOCAK ET AL.: TOP DOWN SALIENCY ESTIMATION 1 Top down saliency estimation via

    E-print Network

    Erdem, Erkut

    KOCAK ET AL.: TOP DOWN SALIENCY ESTIMATION 1 Top down saliency estimation via superpixel et al.'s generic objectness map [1] (on superpixel-level), Yang and Yang's top-down salient object. Alexe, T. Deselares, and V. Ferrari. What is an object? In CVPR, 2010. [2] J. Yang and M.-H. Yang. Top-down

  1. Measurements of top quark properties at CDF

    SciTech Connect

    Kraan, Aafke C.; /Pennsylvania U.

    2006-11-01

    The top quark with its mass of about 172 GeV/c{sup 2} is the most massive fundamental particle observed by experiment. In this talk they highlight the most recent measurements of several top quark properties performed with the CDF detector based on data samples corresponding to integrated luminosities up to 1 fb{sup -1}. These results include a search for top quark pair production via new massive resonances, measurements of the helicity of the W boson from top-quark decay, and a direct limit on the lifetime of the top quark.

  2. Top-down cellular pyramids

    SciTech Connect

    Wu, A.Y.; Rosenfeld, A.

    1982-07-01

    A cellular pyramid is an exponentially tapering stack of arrays of processors ('cells'), where each cell is connected to its neighbors ('siblings') on its own level, to a 'parent' on the level above, and to its 'children' on the level below. It is shown that in some situations, if information flows top-down only, from fathers to sons, then a cellular pyramid may be no faster than a one-level cellular array; but it may be possible to use simpler cells in the pyramid case.

  3. MHD Integrated Topping Cycle Project

    SciTech Connect

    Not Available

    1992-07-01

    This eighteenth quarterly technical progress report of the MHD Integrated Topping cycle Project presents the accomplishments during the period November 1, 1991 to January 31, 1992. The precombustor is fully assembled. Manufacturing of all slagging stage components has been completed. All cooling panels were welded in place and the panel/shell gap was filled with RTV. Final combustor assembly is in progress. The low pressure cooling subsystem (LPCS) was delivered to the CDIF. Second stage brazing issues were resolved. The construction of the two anode power cabinets was completed.

  4. Table-top job analysis

    SciTech Connect

    Not Available

    1994-12-01

    The purpose of this Handbook is to establish general training program guidelines for training personnel in developing training for operation, maintenance, and technical support personnel at Department of Energy (DOE) nuclear facilities. TTJA is not the only method of job analysis; however, when conducted properly TTJA can be cost effective, efficient, and self-validating, and represents an effective method of defining job requirements. The table-top job analysis is suggested in the DOE Training Accreditation Program manuals as an acceptable alternative to traditional methods of analyzing job requirements. DOE 5480-20A strongly endorses and recommends it as the preferred method for analyzing jobs for positions addressed by the Order.

  5. Symmetrical Peripheral Gangrene Following Snake Bite

    PubMed Central

    Shastri, Minal; Parikh, Mital; Patel, Dwijal; Chudasma, Ketan

    2014-01-01

    SPG (Symmetrical peripheral gangrene) is defined as symmetrical distal ischemic damage at two or more sites in the absence of large vessels obstruction. It has been ascribed to a number of infectious and non infectious conditions including connective tissue, cardiovascular, neoplastic and iatrogenic causes. We report a unique case of SPG in a 35-year-old Indian female who developed spontaneous gangrene of the distal phalanges of the right and left index, middle, ring and little fingers and the distal phalanges of all toes of the right and left foot following a snake bite. There have been very few cases of peripheral gangrene and acute renal failure associated with snake bite in literature. PMID:25386476

  6. Symmetric scalar constraint for loop quantum gravity

    NASA Astrophysics Data System (ADS)

    Lewandowski, Jerzy; Sahlmann, Hanno

    2015-02-01

    In the framework of loop quantum gravity, we define a new Hilbert space of states which are solutions of a large number of components of the diffeomorphism constraint. On this Hilbert space, using the methods of Thiemann, we obtain a family of gravitational scalar constraints. They preserve the Hilbert space for every choice of lapse function. Thus adjointness and commutator properties of the constraint can be investigated in a straightforward manner. We show how the space of solutions of the symmetrized constraint can be defined by spectral decomposition, and the Hilbert space of physical states by subsequently fully implementing the diffeomorphism constraint. The relationship of the solutions to those resulting from a proposal for a symmetric constraint operator by Thiemann remains to be elucidated.

  7. Binary switching in a ‘symmetric' potential landscape

    PubMed Central

    Roy, Kuntal; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

    2013-01-01

    A binary switch is the basic building block for information processing. The potential energy profile of a bistable binary switch is a ‘symmetric' double well. The traditional method of switching it from one state (one well) to the other is to tilt the profile towards the desired state. Here, we present a case, where no such tilting is necessary to switch successfully, even in the presence of thermal noise. This happens because of the built-in dynamics inside the switch itself. It differs from the general perception on binary switching that in a ‘symmetric' potential landscape, the switching probability is 50% in the presence of thermal noise. Our results, considering the complete three-dimensional potential landscape, demonstrate intriguing phenomena on binary switching mechanism. With experimentally feasible parameters, we theoretically demonstrate such intriguing possibility in electric field induced magnetization switching of a shape-anisotropic single-domain magnetostrictive nanomagnet with two stable states at room-temperature. PMID:24154561

  8. Mighty Molecule Models

    ERIC Educational Resources Information Center

    Brown, Tom; Rushton, Greg; Bencomo, Marie

    2008-01-01

    As part of the SMATHematics Project: The Wonder of Science, The Power of Mathematics--a collaborative partnership between Kennesaw State University and two local school districts, fifth graders had the opportunity to puzzle out chemical formulas of propane, methanol, and other important molecules. In addition, they explored properties that…

  9. Diversity in Biological Molecules

    ERIC Educational Resources Information Center

    Newbury, H. John

    2010-01-01

    One of the striking characteristics of fundamental biological processes, such as genetic inheritance, development and primary metabolism, is the limited amount of variation in the molecules involved. Natural selective pressures act strongly on these core processes and individuals carrying mutations and producing slightly sub-optimal versions of…

  10. Atoms, Molecules, and Ions

    NSDL National Science Digital Library

    General chemistry WebCT exam/quiz questions. The Atoms, Molecules, and Ions topic covers the basics of the composition of atoms, including subatomic particles, elements, allotropes, and isotopes. Periodic placement and trends, molar mass, and molecular formulas and ions are also included.

  11. Three new 'nonterrestrial' molecules

    NASA Technical Reports Server (NTRS)

    Thaddeus, P.; Guelin, M.; Linke, R. A.

    1981-01-01

    Eight new interstellar lines have been detected from three molecules not previously observed spectroscopically in space or in the laboratory. One is a linear or nearly linear molecule with microwave constants B0 equals 21,337.15 plus or minus 0.06 MHz, D0 equals 21.4 plus or minus 1.5 kHz. This is the thioformyl ion HCS(plus), first identified because B0 and D0 are close to those calculated, and now confirmed by laboratory detection of one of the present lines (Gudeman et al.). The second molecule, also linear or nearly so, has microwave constants B0 equals 10,691,406 plus or minus 0.043 MHz, D0 equals 1.84 plus or minus 0.91 kHz close to those expected for the isoelectronic systems HOCO(plus) and HOCN; a choice between the two cannot be made on the basis of the available astronomical data. The existence of a third molecule is deduced from an unidentified line at 85,338 MHz that has been found in many sources, is fairly intense in several, and may be self-absorbed in Sgr B2.

  12. Sugars as signaling molecules

    Microsoft Academic Search

    Jen Sheen; Li Zhou; Jyun-Chyun Jang

    1999-01-01

    Recent studies indicate that, in a manner similar to classical plant hormones, sugars can act as signaling molecules that control gene expression and developmental processes in plants. Crucial evidence includes uncoupling glucose signaling from its metabolism, identification of glucose sensors, and isolation and characterization of mutants and other regulatory components in plant sugar signal transduction pathways. The emerging scenario points

  13. Algebraic theory of molecules

    NASA Technical Reports Server (NTRS)

    Iachello, Franco

    1995-01-01

    An algebraic formulation of quantum mechanics is presented. In this formulation, operators of interest are expanded onto elements of an algebra, G. For bound state problems in nu dimensions the algebra G is taken to be U(nu + 1). Applications to the structure of molecules are presented.

  14. Halley's polymeric organic molecules

    SciTech Connect

    Huebner, W.F.; Boice, D.C.; Korth, A.

    1989-01-01

    The detection of polymeric organic compounds in the mass spectrum of Comet Halley obtained with the Positive Ion Cluster Composition analyzer on Giotto are examined. It is found that, in addition to polyoxymethylene, other polymers and complex molecules may exist in the comet. It is suggested that polymerized hydrogen cyanide may be a source for the observed CN and NH2 jets. 31 refs.

  15. Halley's polymeric organic molecules

    NASA Technical Reports Server (NTRS)

    Huebner, W. F.; Boice, D. C.; Korth, A.

    1989-01-01

    The detection of polymeric organic compounds in the mass spectrum of Comet Halley obtained with the Positive Ion Cluster Composition analyzer on Giotto are examined. It is found that, in addition to polyoxymethylene, other polymers and complex molecules may exist in the comet. It is suggested that polymerized hydrogen cyanide may be a source for the observed CN and NH2 jets.

  16. Irreducible complexity of iterated symmetric bimodal maps

    Microsoft Academic Search

    J. P. Lampreia; R. Severino; J. Sousa Ramos

    2004-01-01

    We introduce a tree structure for the iterates of symmetric bimodal maps and\\u000aidentify a subset which we prove to be isomorphic to the family of unimodal\\u000amaps. This subset is used as a second factor for a $\\\\ast $-product that we\\u000adefine in the space of bimodal kneading sequences. Finally, we give some\\u000aproperties for this product and study

  17. Irreducible complexity of iterated symmetric bimodal maps

    E-print Network

    J. P. Lampreia; R. Severino; J. Sousa Ramos

    2004-03-08

    We introduce a tree structure for the iterates of symmetric bimodal maps and identify a subset which we prove to be isomorphic to the family of unimodal maps. This subset is used as a second factor for a $\\ast $-product that we define in the space of bimodal kneading sequences. Finally, we give some properties for this product and study the *-product induced on the associated Markov shifts.

  18. Symmetric voltage-controlled variable resistance

    NASA Technical Reports Server (NTRS)

    Vanelli, J. C.

    1978-01-01

    Feedback network makes resistance of field-effect transistor (FET) same for current flowing in either direction. It combines control voltage with source and load voltages to give symmetric current/voltage characteristics. Since circuit produces same magnitude output voltage for current flowing in either direction, it introduces no offset in presense of altering polarity signals. It is therefore ideal for sensor and effector circuits in servocontrol systems.

  19. Index-based symmetric DNA encryption algorithm

    Microsoft Academic Search

    Zhang Yunpeng; Zhu Yu; Wang Zhong; Richard O. Sinnott

    2011-01-01

    In this paper, a new index-based symmetric DNA encryption algorithm has been proposed. Adopting the methods of Block-Cipher and Index of string, the algorithm encrypts the DNA-sequence-based plaintext. First, the algorithm encodes each character into ASCII codes. And then, according to the nucleotide sequence, the researcher should convert it to the DNA coding. Besides, the researcher selects the special DNA

  20. Stabilization of Quantum Computations by Symmetrization

    Microsoft Academic Search

    Adriano Barenco; Andre? Berthiaume; David Deutsch; Artur Ekert; Richard Jozsa; Chiara Macchiavello

    1997-01-01

    We propose a method for the stabilization of quantum computations (including quan- tum state storage). The method is based on the operation of projection intoSYM, the symmetric subspace of the full state space of R redundant copies of the computer. We describe an ecient algorithm and quantum network eectingSYM{projection and discuss the stabilizing eect of the proposed method in the

  1. Peakedness and peakedness ordering in symmetric distributions

    Microsoft Academic Search

    Hammou Elbarmi; Hari Mukerjee

    2009-01-01

    There are many ways to measure the dispersion of a random variable. One such method uses the concept of peakedness. If the random variable X is symmetric about a point ?, then Birnbaum [Z.W. Birnbaum, On random variables with comparable peakedness, The Annals of Mathematical Statistics 19 (1948) 76–81] defined the function P?(x)=P(|X??|?x),x?0, as the peakedness of X. If two

  2. Solitons in PT-symmetric nonlinear lattices

    SciTech Connect

    Abdullaev, Fatkhulla Kh.; Konotop, Vladimir V.; Zezyulin, Dmitry A. [Centro de Fisica Teorica e Computacional, Faculdade de Ciencias, Universidade de Lisboa, Avenida Professor Gama Pinto 2, P-1649-003 Lisboa (Portugal); Kartashov, Yaroslav V. [ICFO-Institut de Ciencies Fotoniques, and Universitat Politecnica de Catalunya, Mediterranean Technology Park, E-08860 Castelldefels, Barcelona (Spain)

    2011-04-15

    The existence of localized modes supported by the PT-symmetric nonlinear lattices is reported. The system considered reveals unusual properties: unlike other typical dissipative systems, it possesses families (branches) of solutions, which can be parametrized by the propagation constant; relatively narrow localized modes appear to be stable, even when the conservative nonlinear lattice potential is absent; and finally, the system supports stable multipole solutions.

  3. Wave equation on spherically symmetric Lorentzian metrics

    SciTech Connect

    Bokhari, Ashfaque H.; Al-Dweik, Ahmad Y.; Zaman, F. D. [Department of Mathematics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Kara, A. H. [School of Mathematics, University of the Witwatersrand, Johannesburg (South Africa); Karim, M. [Department of Physics, St. John Fisher College, Rochester, New York 14618 (United States)

    2011-06-15

    Wave equation on a general spherically symmetric spacetime metric is constructed. Noether symmetries of the equation in terms of explicit functions of {theta} and {phi} are derived subject to certain differential constraints. By restricting the metric to flat Friedman case the Noether symmetries of the wave equation are presented. Invertible transformations are constructed from a specific subalgebra of these Noether symmetries to convert the wave equation with variable coefficients to the one with constant coefficients.

  4. PT symmetric Aubry-Andre model

    NASA Astrophysics Data System (ADS)

    Yuce, C.

    2014-06-01

    PT symmetric Aubry-Andre model describes an array of N coupled optical waveguides with position-dependent gain and loss. We show that the reality of the spectrum depends sensitively on the degree of quasi-periodicity for small number of lattice sites. We obtain the Hofstadter butterfly spectrum and discuss the existence of the phase transition from extended to localized states. We show that rapidly changing periodical gain/loss materials almost conserve the total intensity.

  5. Highly symmetric travelling waves in pipe flow

    Microsoft Academic Search

    Chris C. T. Pringle; Yohann Duguet; Rich R. Kerswell

    2009-01-01

    The recent theoretical discovery of finite-amplitude travelling waves in pipe flow has re-ignited interest in the transitional phenomena that Osborne Reynolds studied 125 years ago. Despite all being unstable, these waves are providing fresh insight into the flow dynamics. Here we describe two new classes of highly-symmetric travelling waves (possessing rotational, shift-&-reflect and mirror symmetries) and report a new family

  6. A naturally light Higgs without light Top Partners

    E-print Network

    Adrian Carmona; Florian Goertz

    2014-10-30

    We demonstrate that the inclusion of a realistic lepton sector can relax significantly the upper bound on top partner masses in minimal composite Higgs models, induced by the lightness of the Higgs boson. To that extend, we present a comprehensive survey of the impact of different realizations of the fermion sectors on the Higgs potential, with a special emphasis on the role of the leptons. The non-negligible compositeness of the $\\tau_R$ in a general class of models that address the flavor structure of the lepton sector and the smallness of the corresponding FCNCs, can have a significant effect on the potential. We find that, with the $\\tau_R$ in the symmetric representation of $SO(5)$, an increase in the maximally allowed mass of the lightest top partner of $\\gtrsim 1$ TeV is possible for minimal quark setups like the MCHM$_{5,10}$, without increasing the tuning. A light Higgs boson $m_H \\sim(100-200)$ GeV is a natural prediction of such models, which thus provide a new setup that can evade ultra-light top partners without ad-hoc tuning in the Higgs mass. Moreover, we advocate a more minimal realization of the lepton sector than generally used in the literature, which still can avoid light partners due to its contributions to the Higgs mass in a different and very natural way, triggered by the seesaw mechanism. This allows to construct the most economical $SO(5)/SO(4)$ composite Higgs models possible. Using both a transparent 4D approach, as well as presenting numerical results in the 5D holographic description, we demonstrate that, including leptons, minimality and naturalness do not imply light partners. Leptonic effects, not considered before, could hence be crucial for the viability of composite models.

  7. Nonthermal and geometric effects on the symmetric and anti-symmetric surface waves in a Lorentzian dusty plasma slab

    NASA Astrophysics Data System (ADS)

    Lee, Myoung-Jae; Jung, Young-Dae

    2015-02-01

    The nonthermal and geometric effects on the propagation of the surface dust acoustic waves are investigated in a Lorentzian dusty plasma slab. The symmetric and anti-symmetric dispersion modes of the dust acoustic waves are obtained by the plasma dielectric function with the spectral reflection conditions the slab geometry. The variation of the nonthermal and geometric effects on the symmetric and the anti-symmetric modes of the surface plasma waves is also discussed.

  8. Relative Equilibria of Molecules

    NASA Astrophysics Data System (ADS)

    Montaldi, J. A.; Roberts, R. M.

    1999-02-01

    We describe a method for finding the families of relative equilibria of molecules that bifurcate from an equilibrium point as the angular momentum is increased from 0 . Relative equilibria are steady rotations about a stationary axis during which the shape of the molecule remains constant. We show that the bifurcating families correspond bijectively to the critical points of a function h on the two-sphere which is invariant under an action of the symmetry group of the equilibrium point. From this it follows that for each rotation axis of the equilibrium configuration there is a bifurcating family of relative equilibria for which the molecule rotates about that axis. In addition, for each reflection plane there is a family of relative equilibria for which the molecule rotates about an axis perpendicular to the plane. We also show that if the equilibrium is nondegenerate and stable, then the minima, maxima, and saddle points of h correspond respectively to relative equilibria which are (orbitally) Liapounov stable, linearly stable, and linearly unstable. The stabilities of the bifurcating branches of relative equilibria are computed explicitly for XY 2 , X 3 , and XY 4 molecules. These existence and stability results are corollaries of more general theorems on relative equilibria of G -invariant Hamiltonian systems that bifurcate from equilibria with finite isotropy subgroups as the momentum is varied. In the general case, the function h is defined on the Lie algebra dual {frak g} * and the bifurcating relative equilibria correspond to critical points of the restrictions of h to the coadjoint orbits in {frak g} * .

  9. The Top American Research Universities 2001

    NSDL National Science Digital Library

    2001-01-01

    An updated version of The Top American Research Universities has been released from Florida-based research organization, The Center, which creates this report annually. (The first edition of the Top American Research Universities was included in the July 28, 2000 Scout Report.) Institutions considered "top" are those that have federal research expenditures as reported to NSF of at least $20 million and that fall within the top 25 on at least one of The Center's nine measures (total research expenditures, federal research expenditures, endowment assets, annual giving, faculty members in the National Academies, faculty awards, doctoral degrees, postdoctoral appointees, and entering freshmen SAT scores). This year, the study has been expanded to include national rankings and to include institutions ranked in the top 26-50 (in addition to those ranked in top 25). The data are available in .pdf or spreadsheet (.xls) format. Interestingly, the top ten are all private universities.

  10. Symmetric smoothing filters from global consistency constraints.

    PubMed

    Haque, Sheikh Mohammadul; Pai, Gautam P; Govindu, Venu Madhav

    2015-05-01

    Many patch-based image denoising methods can be viewed as data-dependent smoothing filters that carry out a weighted averaging of similar pixels. It has recently been argued that these averaging filters can be improved using their doubly stochastic approximation, which are symmetric and stable smoothing operators. In this paper, we introduce a simple principle of consistency that argues that the relative similarities between pixels as imputed by the averaging matrix should be preserved in the filtered output. The resultant consistency filter has the theoretically desirable properties of being symmetric and stable, and is a generalized doubly stochastic matrix. In addition, we can also interpret our consistency filter as a specific form of Laplacian regularization. Thus, our approach unifies two strands of image denoising methods, i.e., symmetric smoothing filters and spectral graph theory. Our consistency filter provides high-quality image denoising and significantly outperforms the doubly stochastic version. We present a thorough analysis of the properties of our proposed consistency filter and compare its performance with that of other significant methods for image denoising in the literature. PMID:25532176

  11. Symmetric multilayer megampere X-pinch

    SciTech Connect

    Shelkovenko, T. A.; Pikuz, S. A. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); McBride, R. D. [Sandia National Laboratories (United States); Knapp, P. F.; Wilhelm, G. [Cornell University (United States); Sinars, D. B. [Sandia National Laboratories (United States); Hammer, D. A. [Cornell University (United States); Orlov, N. Yu. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2010-01-15

    Raising the power of X-ray emission from an X-pinch by increasing the pinch current to the megampere level requires the corresponding increase in the initial linear mass of the load. This can be achieved by increasing either the number of wires or their diameter. In both cases, special measures should be undertaken to prevent the formation of a complicated configuration with an uncontrolled spatial structure in the region of wire crossing, because such a structure breaks the symmetry of the neck formed in the crossing region, destabilizes plasma formation, and degrades X-ray generation. To improve the symmetry of the wire crossing region, X-pinch configurations with a regular multilayer arrangement of wires in this region were proposed and implemented. The results of experiments with various symmetric X-pinch configurations on the COBRA facility at currents of {approx}1MA are presented. It is shown that an X-pinch with a symmetric crossing region consisting of several layers of wires made of different materials can be successfully used in megampere facilities. The most efficient combinations of wires in symmetric multilayer X-pinches are found in which only one hot spot forms and that are characterized by a high and stable soft X-ray yield.

  12. Weyl symmetric structure of QCD vacuum

    E-print Network

    Y. M. Cho; D. G. Pak; P. M. Zhang; L. P. Zou

    2012-09-12

    We consider Weyl symmetric structure of the classical vacuum in quantum chromodynamics. In the framework of formalism of gauge invariant Abelian projection we show that classical vacuums can be constructed in terms of Killing vector fields on the group SU(3). Consequently, homotopic classes of Killing vector fields determine the topological structure of the vacuum. In particular, the second homotopy group \\pi_2(SU(3)/U(1)\\times U(1)) describes all topologically non-equivalent vacuums which are classified by two topological numbers. For each given Killing vector field one can construct six vacuums forming Weyl sextet representation. An interesting feature of SU(3) gauge theory is that it admits a Weyl symmetric vacuum represented by a linear superposition of the six vacuums from the Weyl vacuum sextet. A non-trivial manifestation of Weyl symmetry is demonstrated on monopole solutions. We construct a family of finite energy monopole solutions in Yang-Mills-Higgs theory which includes Weyl monopole sextet. From the analysis of the classical vacuum structure and monopole solutions we conjecture that a similar Weyl symmetric vacuum structure can be realized in quantum theory.

  13. Universal horizons in maximally symmetric spaces

    E-print Network

    Jishnu Bhattacharyya; David Mattingly

    2014-08-27

    Universal horizons in Ho\\v{r}ava-Lifshitz gravity and Einstein-{\\ae}ther theory are the equivalent of causal horizons in general relativity and appear to have many of the same properties, including a first law of horizon thermodynamics and thermal radiation. Since universal horizons are infrared solutions of a putative power counting renormalizable quantum gravitational theory, fully understanding their thermodynamics will shed light on the interplay between black hole thermodynamics and quantum gravity. In this paper, we provide a complete classification, including asymptotic charges, of all four dimensional static and spherically symmetric universal horizon solutions with maximally symmetric asymptotics -- the equivalents of the Schwarzschild, Schwarzschild de Sitter or Schwarzschild anti-de Sitter spacetimes. Additionally we derive the associated first laws for the universal horizon solutions. Finally we prove that independent of asymptotic boundary conditions, any spherically symmetric solution in Ho\\v{r}ava-Lifshitz gravity with a universal horizon is also a solution of Einstein-{\\ae}ther theory, thereby broadening and complementing the known equivalence region of the solution spaces.

  14. Recent advances in small molecule OLED-on-silicon microdisplays

    Microsoft Academic Search

    Amalkumar P. Ghosh; Tariq A. Ali; Ilyas Khayrullin; Fridrich Vazan; Olivier F. Prache; Ihor Wacyk

    2009-01-01

    High resolution OLED-on-silicon microdisplay technology is unique and challenging since it requires very small subpixel dimensions (~ 2-5 microns). eMagin's OLED microdisplay is based on white top emitter architecture using small molecule organic materials. The devices are fabricated using high Tg materials. The devices are hermetically sealed with vacuum deposited thin film layers. LCD-type color filters are patterned using photolithography

  15. Effective torsion-rotation Hamiltonian for methanol-type molecules

    Microsoft Academic Search

    Kuniaki Nakagawa; Shozo Tsunekawa; Takeshi Kojima

    1987-01-01

    A fourth-order effective Hamiltonian has been derived for the torsion-rotation problem of a methanol-type molecule, i.e., for a C3v top attached to a Cs frame. First, symmetry considerations based on a frame-fixed axis system are used to determine allowed terms in the Hamiltonian. These terms are then subjected to a contact transformation to remove the indeterminate ones. This procedure is

  16. Induction of apoptosis in colon cancer cells by a novel topoisomerase I inhibitor TopIn

    SciTech Connect

    Bae, Soo Kyung [College of Pharmacy, The Catholic University of Korea, Bucheon 420-743 (Korea, Republic of)] [College of Pharmacy, The Catholic University of Korea, Bucheon 420-743 (Korea, Republic of); Gwak, Jungsug [Department of Advanced Fermentation Fusion Science and Technology, Kookmin University, Seoul 136-702 (Korea, Republic of)] [Department of Advanced Fermentation Fusion Science and Technology, Kookmin University, Seoul 136-702 (Korea, Republic of); Song, Im-Sook [PharmcoGenomics Research Center, Inje University College of Medicine, Busan 614-735 (Korea, Republic of)] [PharmcoGenomics Research Center, Inje University College of Medicine, Busan 614-735 (Korea, Republic of); Park, Hyung-Soon [Probiond Co., Ltd., Seoul 143-834 (Korea, Republic of)] [Probiond Co., Ltd., Seoul 143-834 (Korea, Republic of); Oh, Sangtaek, E-mail: ohsa@kookmin.ac.kr [Department of Advanced Fermentation Fusion Science and Technology, Kookmin University, Seoul 136-702 (Korea, Republic of)] [Department of Advanced Fermentation Fusion Science and Technology, Kookmin University, Seoul 136-702 (Korea, Republic of)

    2011-05-27

    Highlights: {yields} TopIn activates p53-dependent transcription in colon cancer cells. {yields} TopIn induces apoptosis in colon cancer cells. {yields} TopIn selectively inhibits topoisomerase I activity. {yields} TopIn does not affect the activity of BCRP and MDR-1. -- Abstract: The tumor suppressor p53 plays an important role in cellular emergency mechanisms through regulating the genes involved in cell cycle arrest and apoptosis. To identify small molecules that can activate p53-responsive transcription, we performed chemical screening using genetically engineered HCT116 reporter cells. We found that TopIn (7-phenyl-6H-[1,2,5]oxadiazolo[3,4-e]indole 3-oxide) efficiently activated p53-mediated transcriptional activity and induced phosphorylation of p53 at Ser15, thereby stabilizing the p53 protein. Furthermore, TopIn upregulated the expression of p21{sup WAF1/CIP1}, a downstream target of p53, and suppressed cellular proliferation in various colon cancer cells. Additionally, TopIn induced DNA fragmentation, caspase-3/7 activation and poly ADP ribose polymerase cleavage, typical biochemical markers of apoptosis, in p53 wild-type and mutated colon cancer cells. Finally, we found that TopIn inhibited topoisomerase I activity, but not topoisomerase II, in vitro and induced the formation of the topoisomerase I-DNA complex in HCT116 colon cancer cells. Unlike camptothecin (CPT) and its derivative SN38, TopIn did not affect the activity of the ATP-binding cassette transporter breast cancer resistance protein (BCRP) or multidrug-resistant protein-1 (MDR-1). These results suggest that TopIn may present a promising new topoisomerase I-targeting anti-tumor therapeutics.

  17. Top quark physics at CDF

    SciTech Connect

    Caner, A. [European Organization for Nuclear Research, Geneva (Switzerland). PPE Div.; CDF Collaboration

    1996-08-01

    We present preliminary results on top quark physics recently obtained by the CDF collaboration. The data sample consists of 110 {ital pb}{sup -1} of {ital p{anti p}} collisions at {radical}{ital s} = 1.8 TeV, collected with the Collider Detector at Fermilab during the period 1992 - 1995. We report on the {ital t{anti t}} production cross section and on the top quark mass. The measurements are made in three topologies, corresponding to the decay modes of the {ital Wb} pairs in the final state: lepton + multi-jets, dilepton and all hadronic final state. The analysis performed on the single lepton sample yields the most accurate measurements, due to the good acceptance and the favorable signal to noise ratio obtained after applying some b-tagging techniques. In this channel we measure: {sigma}{sub {ital t{anti t}}} = 6.8{sup +2.3}{sub -1.8} pb M{sub {ital t}} = 175.6 {+-} 5.7 ({ital stat}) {+-} 7.1 ({ital syst.}) {ital GeV/c{sup 2}} Combining the cross sections measured with the lepton + multi-jet and dilepton data we obtain: {sigma}{sub {ital t{anti t}}} = 7.5{sup +1.9}{sub -1.6} {ital pb} A preliminary investigation of the production mechanism of the {ital t{anti t}} system is shown and compared to Standard Model expectations.

  18. MHD integrated topping cycle project

    NASA Astrophysics Data System (ADS)

    1992-01-01

    The overall objective of the project is to design and construct prototypical hardware for an integrated MHD topping cycle, and conduct long duration proof-of-concept tests of integrated system at the US DOE Component Development and Integration Facility in Butte, Montana. The results of the long duration tests will augment the existing engineering design data base on MHD power train reliability, availability, maintainability, and performance, and will serve as a basis for scaling up the topping cycle design to the next level of development, an early commercial scale power plant retrofit. The components of the MHD power train to be designed, fabricated, and tested include: A slagging coal combustor with a rated capacity of 50 MW thermal input, capable of operation with an Eastern (Illinois no. 6) or Western (Montana Rosebud) coal, a segmented supersonic nozzle, a supersonic MHD channel capable of generating at least 1.5 MW of electrical power, a segmented supersonic diffuser section to interface the channel with existing facility quench and exhaust systems, a complete set of current control circuits for local diagonal current control along the channel, and a set of current consolidation circuits to interface the channel with the existing facility inverter.

  19. MHD Integrated Topping Cycle Project

    NASA Astrophysics Data System (ADS)

    1992-03-01

    The Magnetohydrodynamics (MHD) Integrated Topping Cycle (ITC) Project represents the culmination of the proof-of-concept (POC) development stage in the US Department of Energy (DOE) program to advance MHD technology to the early commercial development stage for utility power applications. The project is a joint effort, combining the skills of three topping cycle component developers: TRW, Avco/TDS, and Westinghouse. TRW, the prime contractor and system integrator, is responsible for the 50 thermal megawatt (50 MW(sub t)) slagging coal combustion subsystem. Avco/TDS is responsible for the MHD channel subsystem (nozzle, channel, diffuser, and power conditioning circuits), and Westinghouse is responsible for the current consolidation subsystem. The ITC Project will advance the state-of-the-art in MHD power systems with the design, construction, and integrated testing of 50 MW(sub t) power train components which are prototypical of the equipment that will be used in an early commercial scale MHD utility retrofit. Long duration testing of the integrated power train at the Component Development and Integration Facility (CDIF) in Butte, Montana will be performed, so that by the early 1990's, an engineering data base on the reliability, availability, maintainability, and performance of the system will be available to allow scaleup of the prototypical designs to the next development level.

  20. MHD Integrated Topping Cycle Project

    SciTech Connect

    Not Available

    1992-03-01

    The Magnetohydrodynamics (MHD) Integrated Topping Cycle (ITC) Project represents the culmination of the proof-of-concept (POC) development stage in the US Department of Energy (DOE) program to advance MHD technology to early commercial development stage utility power applications. The project is a joint effort, combining the skills of three topping cycle component developers: TRW, Avco/TDS, and Westinghouse. TRW, the prime contractor and system integrator, is responsible for the 50 thermal megawatt (50 MW{sub t}) slagging coal combustion subsystem. Avco/TDS is responsible for the MHD channel subsystem (nozzle, channel, diffuser, and power conditioning circuits), and Westinghouse is responsible for the current consolidation subsystem. The ITC Project will advance the state-of-the-art in MHD power systems with the design, construction, and integrated testing of 50 MW{sub t} power train components which are prototypical of the equipment that will be used in an early commercial scale MHD utility retrofit. Long duration testing of the integrated power train at the Component Development and Integration Facility (CDIF) in Butte, Montana will be performed, so that by the early 1990's, an engineering data base on the reliability, availability, maintainability and performance of the system will be available to allow scaleup of the prototypical designs to the next development level. This Sixteenth Quarterly Technical Progress Report covers the period May 1, 1991 to July 31, 1991.

  1. MHD Integrated Topping Cycle Project

    SciTech Connect

    Not Available

    1992-01-01

    The overall objective of the project is to design and construct prototypical hardware for an integrated MHD topping cycle, and conduct long duration proof-of-concept tests of integrated system at the US DOE Component Development and Integration Facility in Butte, Montana. The results of the long duration tests will augment the existing engineering design data base on MHD power train reliability, availability, maintainability, and performance, and will serve as a basis for scaling up the topping cycle design to the next level of development, an early commercial scale power plant retrofit. The components of the MHD power train to be designed, fabricated, and tested include: A slagging coal combustor with a rated capacity of 50 MW thermal input, capable of operation with an Eastern (Illinois {number sign}6) or Western (Montana Rosebud) coal, a segmented supersonic nozzle, a supersonic MHD channel capable of generating at least 1.5 MW of electrical power, a segmented supersonic diffuser section to interface the channel with existing facility quench and exhaust systems, a complete set of current control circuits for local diagonal current control along the channel, and a set of current consolidation circuits to interface the channel with the existing facility inverter.

  2. Symmetric Resonance Charge Exchange Cross Section Based on Impact Parameter Treatment

    NASA Technical Reports Server (NTRS)

    Omidvar, Kazem; Murphy, Kendrah; Atlas, Robert (Technical Monitor)

    2002-01-01

    Using a two-state impact parameter approximation, a calculation has been carried out to obtain symmetric resonance charge transfer cross sections between nine ions and their parent atoms or molecules. Calculation is based on a two-dimensional numerical integration. The method is mostly suited for hydrogenic and some closed shell atoms. Good agreement has been obtained with the results of laboratory measurements for the ion-atom pairs H+-H, He+-He, and Ar+-Ar. Several approximations in a similar published calculation have been eliminated.

  3. Spherical Top-Hat Collapse of Viscous Modified Chaplygin Gas in Einstein's Gravity and Loop Quantum Cosmology

    E-print Network

    Debnath, Ujjal

    2015-01-01

    In this work, we focus on the collapse of a spherically symmetric perturbation, with a classical top-hat profile, to study the nonlinear evolution of only viscous modified Chaplygin gas (VMCG) perturbations in Einstein's gravity as well as in loop quantum Cosmology (LQC). In the perturbed region, we have investigated the natures of equation of state parameter, square speed of sound and another perturbed quantities. The results have been analyzed by numerical and graphical investigations.

  4. Spherical Top-Hat Collapse of Viscous Modified Chaplygin Gas in Einstein's Gravity and Loop Quantum Cosmology

    E-print Network

    Ujjal Debnath; Mubasher Jamil

    2015-01-03

    In this work, we focus on the collapse of a spherically symmetric perturbation, with a classical top-hat profile, to study the nonlinear evolution of only viscous modified Chaplygin gas (VMCG) perturbations in Einstein's gravity as well as in loop quantum Cosmology (LQC). In the perturbed region, we have investigated the natures of equation of state parameter, square speed of sound and another perturbed quantities. The results have been analyzed by numerical and graphical investigations.

  5. Strange skyrmion molecules

    SciTech Connect

    Kopeliovich, Vladimir B.; Stern, Boris E. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary Prospect 7A, Moscow 117312 (Russian Federation)

    1997-05-20

    Composed skyrmions with B=2, strangeness content close to 0.5 and the binding energy of several tens of Mev are described. These skyrmions are obtained starting from the system of two B=1 hedgehogs located in different SU(2) subgroups of SU(3) and have the mass and baryon number distribution of molecular (dipole) type. The quantization of zero modes of skyrmion molecules and physics consequences of their existence are discussed.

  6. Strange skyrmion molecules

    NASA Astrophysics Data System (ADS)

    Kopeliovich, Vladimir B.; Stern, Boris E.

    1997-05-01

    Composed skyrmions with B=2, strangeness content close to 0.5 and the binding energy of several tens of Mev are described. These skyrmions are obtained starting from the system of two B=1 hedgehogs located in different SU(2) subgroups of SU(3) and have the mass and baryon number distribution of molecular (dipole) type. The quantization of zero modes of skyrmion molecules and physics consequences of their existence are discussed.

  7. Let's Make Molecules

    NSDL National Science Digital Library

    2014-08-27

    In this activity, learners use gumdrops and toothpicks to model the composition and molecular structure of three greenhouse gases: carbon dioxide (CO2), water vapor (H2O) and methane (CH4). Learners explore how greenhouse gases are released into the atmosphere as well as how these gases contribute to global climate change. This activity guide includes an extension activity in which learners move their bodies to model the arrangement of atoms in a methane molecule.

  8. Negative ions of polyatomic molecules.

    PubMed Central

    Christophorou, L G

    1980-01-01

    In this paper general concepts relating to, and recent advances in, the study of negative ions of polyatomic molecules area discussed with emphasis on halocarbons. The topics dealt with in the paper are as follows: basic electron attachment processes, modes of electron capture by molecules, short-lived transient negative ions, dissociative electron attachment to ground-state molecules and to "hot" molecules (effects of temperature on electron attachment), parent negative ions, effect of density, nature, and state of the medium on electron attachment, electron attachment to electronically excited molecules, the binding of attached electrons to molecules ("electron affinity"), and the basic and the applied significance of negative-ion studies. PMID:7428744

  9. Model molecules mimicking asphaltenes.

    PubMed

    Sjöblom, Johan; Simon, Sébastien; Xu, Zhenghe

    2015-04-01

    Asphalthenes are typically defined as the fraction of petroleum insoluble in n-alkanes (typically heptane, but also hexane or pentane) but soluble in toluene. This fraction causes problems of emulsion formation and deposition/precipitation during crude oil production, processing and transport. From the definition it follows that asphaltenes are not a homogeneous fraction but is composed of molecules polydisperse in molecular weight, structure and functionalities. Their complexity makes the understanding of their properties difficult. Proper model molecules with well-defined structures which can resemble the properties of real asphaltenes can help to improve this understanding. Over the last ten years different research groups have proposed different asphaltene model molecules and studied them to determine how well they can mimic the properties of asphaltenes and determine the mechanisms behind the properties of asphaltenes. This article reviews the properties of the different classes of model compounds proposed and present their properties by comparison with fractionated asphaltenes. After presenting the interest of developing model asphaltenes, the composition and properties of asphaltenes are presented, followed by the presentation of approaches and accomplishments of different schools working on asphaltene model compounds. The presentation of bulk and interfacial properties of perylene-based model asphaltene compounds developed by Sjöblom et al. is the subject of the next part. Finally the emulsion-stabilization properties of fractionated asphaltenes and model asphaltene compounds is presented and discussed. PMID:25638443

  10. Molecules in interstellar clouds

    NASA Astrophysics Data System (ADS)

    Irvine, W. M.; Hjalmarson, A.; Rydbeck, O. E. H.

    The physical conditions and chemical compositions of the gas in interstellar clouds are reviewed in light of the importance of interstellar clouds for star formation and the origin of life. The Orion A region is discussed as an example of a giant molecular cloud where massive stars are being formed, and it is pointed out that conditions in the core of the cloud, with a kinetic temperature of about 75 K and a density of 100,000-1,000,000 molecules/cu cm, may support gas phase ion-molecule chemistry. The Taurus Molecular Clouds are then considered as examples of cold, dark, relatively dense interstellar clouds which may be the birthplaces of solar-type stars and which have been found to contain the heaviest interstellar molecules yet discovered. The molecular species identified in each of these regions are tabulated, including such building blocks of biological monomers as H2O, NH3, H2CO, CO, H2S, CH3CN and H2, and more complex species such as HCOOCH3 and CH3CH2CN.

  11. MHD Integrated Topping Cycle Project

    SciTech Connect

    Not Available

    1992-07-01

    This seventeenth quarterly technical progress report of the MHD Integrated Topping Cycle Project presents the accomplishments during the period August 1, 1991 to October 31, 1991. Manufacturing of the prototypical combustor pressure shell has been completed including leak, proof, and assembly fit checking. Manufacturing of forty-five cooling panels was also completed including leak, proof, and flow testing. All precombustor internal components (combustion can baffle and swirl box) were received and checked, and integration of the components was initiated. A decision was made regarding the primary and backup designs for the 1A4 channel. The assembly of the channel related prototypical hardware continued. The cathode wall electrical wiring is now complete. The mechanical design of the diffuser has been completed.

  12. Three-Dimensional Solutions for Contact Area in Laminated Composite Pinned Joints with Symmetric and Non-Symmetric Stacking Sequences

    NASA Astrophysics Data System (ADS)

    Javadi, H.; Rajabi, I.; Yavari, V.; Kadivar, M. H.

    The aim of this study is computing and evaluating the behavior of the laminated composite plate at the contact area in single lap, mechanically fastened joints. The analyses involve three dimensional finite element models performed by ABAQUS 6.4-PR11 code to evaluate the stress distribution in contact surface, separation angle, the magnitude and location of maximum radial stress. Results are determined for composite laminates with different layer configurations and attempts are made to validate the models with previous works. For cross ply and angle ply configurations only symmetric stacking sequences are used while for quasi-isotropic laminate both symmetric and non-symmetric models are generated. In cross-ply laminate symmetric separation about bearing plane could be found while in quasi-isotropic and angle-ply laminates non-symmetric separation occurs. Also, the separation angle is less than 90° in symmetric laminates and greater than 90° in some plies of non-symmetric laminates.

  13. Symmetrical and anti-symmetrical coherent perfect absorption for acoustic waves

    SciTech Connect

    Wei, Pengjiang; Croënne, Charles; Tak Chu, Sai [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Li, Jensen, E-mail: j.li@bham.ac.uk [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom)

    2014-03-24

    We investigate tunable acoustic absorption enabled by the coherent control of input waves. It relies on coherent perfect absorption originally proposed in optics. By designing appropriate acoustic metamaterial structures with resonating effective bulk modulus or density, we show that complete absorption of incident waves impinging on the metamaterial can be achieved for either symmetrical or anti-symmetrical inputs in the forward and backward directions. By adjusting the relative phase between the two incident beams, absorption can be tuned effectively from unity to zero, making coherent control useful in applications like acoustic modulators, noise controllers, transducers, and switches.

  14. High-Resolution Infrared Spectroscopy Slit-Jet Cooled Hydroxymethyl Radical (CH_2OH): CH Symmetric Stretching Mode

    NASA Astrophysics Data System (ADS)

    Wang, Fang; Chang, Chih-Hsuan; Nesbitt, David

    2014-06-01

    Hydroxymethyl radical (CH_2OH) plays an important role in combustion and environmental chemistry as a reactive intermediate. Reisler's group published the first rotationally resolved spectroscopy of CH_2OH with determined band origins for fundamental CH symmetric stretch state, CH asymmetric stretch state and OH stretch state, respectively. Here CH_2OH was first studied via sub-Doppler infrared spectroscopy in a slit-jet supersonic discharge expansion source. Rotationally resolved direct absorption spectra in the CH symmetric stretching mode were recorded. As a result of the low rotational temperature and sub-Doppler linewidths, the tunneling splittings due to the large amplitude of COH torsion slightly complicate the spectra. Each of the ground vibration state and the CH symmetric stretch state includes two levels. One level, with a 3:1 nuclear spin statistic ratio for Ka=0+/Ka=1+, is labeled as ``+". The other tunneling level, labeled as ``-", has Ka=0-/Ka=1- states with 1:3 nuclear spin statistics. Except for the Ka=0+ ? 0+ band published before, more bands (Ka=1+ ? 1+, Ka=0- ? 0- and Ka=1- ? 1-) were identified. The assigned transitions were fit to a Watson A-reduced symmetric top Hamiltonian to improve the accuracy of the band origin of CH symmetric state. The rotational parameters for both ground and CH symmetric stretch state were well determined. L. Feng, J. Wei and H. Reisler, J. Phys. Chem. A, Vol. 108. M. A. Roberts, E. N. Sharp-Williams and D. J. Nesbitt, J. Phys. Chem. A 2013, 117, 7042-7049

  15. Monte Carlo simulations for top pair and single top production at the Tevatron

    SciTech Connect

    Husemann, U.; /DESY

    2008-06-01

    Monte Carlo (MC) simulations are indispensable tools for top quark physics, both at the current Tevatron collider and the upcoming Large Hadron Collider. In this paper we review how the Tevatron experiments CDF and D0 utilize MC simulations for top quark analyses. We describe the standard MC generators used to simulate top quark pair and single top quark production, followed by a discussion of methods to extract systematic uncertainties of top physics results related to the MC generator choice. The paper also shows the special MC requirements for some example top properties measurements at the Tevatron.

  16. Monte Carlo Simulations for Top Pair and Single Top Production at the Tevatron

    E-print Network

    U. Husemann

    2008-07-29

    Monte Carlo (MC) simulations are indispensable tools for top quark physics, both at the current Tevatron collider and the upcoming Large Hadron Collider. In this paper we review how the Tevatron experiments CDF and D0 utilize MC simulations for top quark analyses. We describe the standard MC generators used to simulate top quark pair and single top quark production, followed by a discussion of methods to extract systematic uncertainties of top physics results related to the MC generator choice. The paper also shows the special MC requirements for some example top properties measurements at the Tevatron.

  17. TOP500 Supercomputers for June 2004

    SciTech Connect

    Strohmaier, Erich; Meuer, Hans W.; Dongarra, Jack; Simon, Horst D.

    2004-06-23

    23rd Edition of TOP500 List of World's Fastest Supercomputers Released: Japan's Earth Simulator Enters Third Year in Top Position MANNHEIM, Germany; KNOXVILLE, Tenn.;&BERKELEY, Calif. In what has become a closely watched event in the world of high-performance computing, the 23rd edition of the TOP500 list of the world's fastest supercomputers was released today (June 23, 2004) at the International Supercomputer Conference in Heidelberg, Germany.

  18. TOP500 Supercomputers for June 2005

    SciTech Connect

    Strohmaier, Erich; Meuer, Hans W.; Dongarra, Jack; Simon, Horst D.

    2005-06-22

    25th Edition of TOP500 List of World's Fastest Supercomputers Released: DOE/L LNL BlueGene/L and IBM gain Top Positions MANNHEIM, Germany; KNOXVILLE, Tenn.; BERKELEY, Calif. In what has become a closely watched event in the world of high-performance computing, the 25th edition of the TOP500 list of the world's fastest supercomputers was released today (June 22, 2005) at the 20th International Supercomputing Conference (ISC2005) in Heidelberg Germany.

  19. TOP500 Supercomputers for November 2004

    SciTech Connect

    Strohmaier, Erich; Meuer, Hans W.; Dongarra, Jack; Simon, Horst D.

    2004-11-08

    24th Edition of TOP500 List of World's Fastest Supercomputers Released: DOE/IBM BlueGene/L and NASA/SGI's Columbia gain Top Positions MANNHEIM, Germany; KNOXVILLE, Tenn.; BERKELEY, Calif. In what has become a closely watched event in the world of high-performance computing, the 24th edition of the TOP500 list of the worlds fastest supercomputers was released today (November 8, 2004) at the SC2004 Conference in Pittsburgh, Pa.

  20. Maximum tunneling velocities in symmetric double well potentials

    E-print Network

    Jörn Manz; Axel Schild; Burkhard Schmidt; Yonggang Yang

    2014-04-23

    We consider coherent tunneling of one-dimensional model systems in non-cyclic or cyclic symmetric double well potentials. Generic potentials are constructed which allow for analytical estimates of the quantum dynamics in the non-relativistic deep tunneling regime, in terms of the tunneling distance, barrier height and mass (or moment of inertia). For cyclic systems, the results may be scaled to agree well with periodic potentials for which semi-analytical results in terms of Mathieu functions exist. Starting from a wavepacket which is initially localized in one of the potential wells, the subsequent periodic tunneling is associated with tunneling velocities. These velocities (or angular velocities) are evaluated as the ratio of the flux densities versus the probability densities. The maximum velocities are found under the top of the barrier where they scale as the square root of the ratio of barrier height and mass (or moment of inertia), independent of the tunneling distance. They are applied exemplarily to several prototypical molecular models of non-cyclic and cyclic tunneling, including ammonia inversion, Cope rearrangment of semibullvalene, torsions of molecular fragments, and rotational tunneling in strong laser fields. Typical maximum velocities and angular velocities are in the order of a few km/s and from 10 to 100 THz for our non-cyclic and cyclic systems, respectively, much faster than time-averaged velocities. Even for the more extreme case of an electron tunneling through a barrier of height of one Hartree, the velocity is only about one percent of the speed of light. Estimates of the corresponding time scales for passing through {the narrow domain just} below the potential barrier are in the domain from 2 to 40 fs, much shorter than the tunneling times.

  1. Symmetric functions and the Vandermonde matrix

    NASA Astrophysics Data System (ADS)

    Oruc, Halil; Akmaz, Hakan K.

    2004-11-01

    This work deduces the lower and the upper triangular factors of the inverse of the Vandermonde matrix using symmetric functions and combinatorial identities. The L and U matrices are in turn factored as bidiagonal matrices. The elements of the upper triangular matrices in both the Vandermonde matrix and its inverse are obtained recursively. The particular value xi=1+q+...+qi-1 in the indeterminates of the Vandermonde matrix is investigated and it leads to q-binomial and q-Stirling matrices. It is also shown that q-Stirling matrices may be obtained from the Pascal matrix.

  2. A lateral symmetrically bistable buckled beam

    NASA Astrophysics Data System (ADS)

    Vangbo, Mattias; Bäcklund, Ylva

    1998-03-01

    We have micromachined a lateral symmetrically bistable buckled beam for snap-in holding structures by oxidizing released beams micromachined on thick silicon-on-insulator wafers. The wafers were prepared by bonding and chemical mechanical polishing, and the structures were fabricated by deep silicon reactive ion etching using the black silicon method, subsequently released and thermally oxidized. The bistability was monitored in situ in a scanning electron microscope using a micromanipulator. Guidelines for designing beams of an expected performance are given and arguments for considering beams that are not `fairly slender' have been found.

  3. Expanding symmetric multiprocessor capability through gang scheduling

    SciTech Connect

    Jette, M.A.

    1998-03-01

    Symmetric Multiprocessor (SMP) systems normally provide both space- sharing and time-sharing to insure high system utilization and good responsiveness. However the prevailing lack of concurrent scheduling for parallel programs precludes SMP use in addressing many large-scale problems. Tightly synchronized communications are impractical and normal time-sharing reduces the benefit of cache memory. Evidence gathered at Lawrence Livermore National Laboratory (LLNL) indicates that gang scheduling can increase the capability of SMP systems and parallel program performance without adverse impact upon system utilization or responsiveness.

  4. Quantum asymmetric cryptography with symmetric keys

    E-print Network

    Fei Gao; Qiao-Yan Wen; Su-Juan Qin; Fu-Chen Zhu

    2008-10-16

    Based on quantum encryption, we present a new idea for quantum public-key cryptography (QPKC) and construct a whole theoretical framework of a QPKC system. We show that the quantum-mechanical nature renders it feasible and reasonable to use symmetric keys in such a scheme, which is quite different from that in conventional public-key cryptography. The security of our scheme is analyzed and some features are discussed. Furthermore, the state-estimation attack to a prior QPKC scheme is demonstrated.

  5. Quantum exchange interaction of spherically symmetric plasmoids

    E-print Network

    Dvornikov, Maxim

    2011-01-01

    We study nano-sized spherically symmetric plasma structures which are radial nonlinear oscillations of electrons in plasma. The effective interaction of these plasmoids via quantum exchange forces between ions is described. We calculate the energy of this interaction for the realistic case of an atmospheric plasma. The conditions when the exchange interaction is attractive are examined and it is shown that separate plasmoids can form a single object. The application of our results to the theoretical description of stable atmospheric plasma structures is considered.

  6. PT-symmetric quantum state discrimination

    E-print Network

    Carl M. Bender; Dorje C. Brody; Joao Caldeira; Bernard K. Meister

    2010-11-08

    Suppose that a system is known to be in one of two quantum states, $|\\psi_1 > $ or $|\\psi_2 >$. If these states are not orthogonal, then in conventional quantum mechanics it is impossible with one measurement to determine with certainty which state the system is in. However, because a non-Hermitian PT-symmetric Hamiltonian determines the inner product that is appropriate for the Hilbert space of physical states, it is always possible to choose this inner product so that the two states $|\\psi_1 > $ and $|\\psi_2 > $ are orthogonal. Thus, quantum state discrimination can, in principle, be achieved with a single measurement.

  7. Design of spherical symmetric gradient index lenses

    NASA Astrophysics Data System (ADS)

    Miñano, Juan C.; Grabovi?ki?, Dejan; Benítez, Pablo; González, Juan C.; Santamaría, Asunción

    2012-10-01

    Spherical symmetric refractive index distributions also known as Gradient Index lenses such as the Maxwell-Fish-Eye (MFE), the Luneburg or the Eaton lenses have always played an important role in Optics. The recent development of the technique called Transformation Optics has renewed the interest in these gradient index lenses. For instance, Perfect Imaging within the Wave Optics framework has recently been proved using the MFE distribution. We review here the design problem of these lenses, classify them in two groups (Luneburg moveable-limits and fixed-limits type), and establish a new design techniques for each type of problem.

  8. Communities and classes in symmetric fractals

    NASA Astrophysics Data System (ADS)

    Krawczyk, Ma?gorzata J.

    2015-07-01

    Two aspects of fractal networks are considered: the community structure and the class structure, where classes of nodes appear as a consequence of a local symmetry of nodes. The analyzed systems are the networks constructed for two selected symmetric fractals: the Sierpinski triangle and the Koch curve. Communities are searched for by means of a set of differential equations. Overlapping nodes which belong to two different communities are identified by adding some noise to the initial connectivity matrix. Then, a node can be characterized by a spectrum of probabilities of belonging to different communities. Our main goal is that the overlapping nodes with the same spectra belong to the same class.

  9. Ultra-cold molecule production.

    SciTech Connect

    Ramirez-Serrano, Jamie; Chandler, David W.; Strecker, Kevin; Rahn, Larry A.

    2005-12-01

    The production of Ultra-cold molecules is a goal of many laboratories through out the world. Here we are pursuing a unique technique that utilizes the kinematics of atomic and molecular collisions to achieve the goal of producing substantial numbers of sub Kelvin molecules confined in a trap. Here a trap is defined as an apparatus that spatially localizes, in a known location in the laboratory, a sample of molecules whose temperature is below one degree absolute Kelvin. Further, the storage time for the molecules must be sufficient to measure and possibly further cool the molecules. We utilize a technique unique to Sandia to form cold molecules from near mass degenerate collisions between atoms and molecules. This report describes the progress we have made using this novel technique and the further progress towards trapping molecules we have cooled.

  10. Observations of severe turbulence near thunderstorm tops

    NASA Technical Reports Server (NTRS)

    Pantley, K. C.; Lester, Peter F.

    1990-01-01

    Data derived from the flight tapes of two airliners that experienced severe turbulence near thunderstorm tops are used to produce quantitative descriptions of the turbulence and its environment. The likely turbulence-producing processes include a three-dimensional turbulent wake in the lee of a squall line and an updraft in the top of a thunderstorm. Results suggest that current procedures for using surface and airborne weather radar for routing aircraft near thunderstorm tops should be reexamined. Also, although useful rules for safe flight near thunderstorm tops already exist, there is evidence that they are not universally applied.

  11. Nonrelativistic effective field theory of unstable top

    E-print Network

    Alexander A. Penin; Jan H. Piclum

    2012-09-18

    We develop a new nonrelativistic effective field theory of $\\rho$NRQCD [1] to describe the finite lifetime effects in the threshold production of top quark-antiquark pairs. The theory is based on the expansion in a parameter $\\rho=1-m_W/m_t$ characterizing the dynamics of the top-quark decay. Within this framework we compute the nonresonant contribution to the total cross section of the top quark-antiquark threshold production in electron-positron annihilation up to the next-to-next-to-leading order. Our method naturally resolves the problem of spurious divergences in the analysis of the unstable top production.

  12. Adsorption of pairs of NO x molecules on single-walled carbon nanotubes and formation of NO + NO 3 from NO 2

    Microsoft Academic Search

    Jiayu Dai; Paolo Giannozzi; Jianmin Yuan

    2009-01-01

    The adsorption of NOx(x=1,2,3) molecules on single-walled carbon nanotubes (SWCNTs) is investigated using first-principle calculations. Single NO, NO2 and NO3 molecules are found to physisorb on SWCNTs, but molecules can be chemisorbed in pairs on the top of carbon atoms at close sites of SWCNTs. The adsorption energy for pairs of NO or NO3 molecules is larger than for pairs

  13. Inorganic Molecules; A Visual Database

    NSDL National Science Digital Library

    Inorganic Molecules: A Visual Data Base contains text and graphics describing 66 molecules and ions commonly used as examples in general chemistry courses. For each molecule, fifteen molecular properties are presented visually by eight or nine different molecular models created by the CAChe Scientific Molecular Modeling program.

  14. Fluorophores for single molecule microscopy

    Microsoft Academic Search

    G. J. Schütz; H. J. Gruber; H. Schindler; Th. Schmidt

    1997-01-01

    The fluorescence photoncount distributions, photobleaching characteristics, and saturation intensities of the commonly used fluorescence tags tetramethylrhodamine and phycoerythrin were measured on the level of individual molecules. Although, the fluorescence properties of phycoerythrin seem to be superior in view of single molecule detection, the increased photostability of tetramethylrhodamine coupled both, to a lipid or an antibody, makes it the molecule of

  15. Decay Structure for Symmetric Hyperbolic Systems with Non-Symmetric Relaxation and its Application

    NASA Astrophysics Data System (ADS)

    Ueda, Yoshihiro; Duan, Renjun; Kawashima, Shuichi

    2012-07-01

    This paper is concerned with the decay structure for linear symmetric hyperbolic systems with relaxation. When the relaxation matrix is symmetric, the dissipative structure of the systems is completely characterized by the Kawashima-Shizuta stability condition formulated in Umeda et al. (Jpn J Appl Math 1:435-457, 1984) and Shizuta and Kawashima (Hokkaido Math J 14:249-275, 1985) and we obtain the asymptotic stability result together with the explicit time-decay rate under that stability condition. However, some physical models which satisfy the stability condition have non-symmetric relaxation term (for example, the Timoshenko system and the Euler-Maxwell system). Moreover, it had been already known that the dissipative structure of such systems is weaker than the standard type and is of the regularity-loss type (see Duan in J Hyperbolic Differ Equ 8:375-413, 2011; Ide et al. in Math Models Meth Appl Sci 18:647-667, 2008; Ide and Kawashima in Math Models Meth Appl Sci 18:1001-1025, 2008; Ueda et al. in SIAM J Math Anal 2012; Ueda and Kawashima in Methods Appl Anal 2012). Therefore our purpose in this paper is to formulate a new structural condition which includes the Kawashima-Shizuta condition, and to analyze the weak dissipative structure for general systems with non-symmetric relaxation.

  16. Fast numerical determination of symmetric sparsity patterns

    SciTech Connect

    Carter, R.G. [Univ. of Minnesota, Minneapolis (United States)

    1994-08-01

    The author considers a function g: {Re}{sup n} {yields} {Re}{sup n} for which the Jacobian is symmetric and sparse. Such functions often arise, for instance, in numerical optimization, where g is the gradient of some objective function f so that the Jacobian of g is the Hessian of f. In many such applications one can generate extremely efficient algorithms by taking advantage of the sparsity structure of the problem if this pattern is known a priori. Unfortunately, determining such sparsity structures by hand is often difficult and prone to error. If one suspects a mistake has been made, or if g is a {open_quotes}black box{close_quotes} so that the true structure is completely unknown, one often has no alternative but to compute the entire matrix by finite differences - a prohibitively expensive task for large problems. The author shows that it is possible to numerically determine symmetric sparsity patterns using a relatively small number of g evaluations. Numerical results are shown for n up to 100,000 in which all nonzeros in the Jacobian are correctly identified in about one-hundredth of the time required to estimate the sparsity structure by a full finite difference calculation. When a good initial guess for the sparsity structure is available, numerical results are presented for n up to 500,000, in which all missing nonzeros are correctly located almost five-thousand times faster than would be possible with a full finite difference calculation.

  17. Transformations between symmetric sets of quantum states

    E-print Network

    Vedran Dunjko; Erika Andersson

    2012-06-22

    We investigate probabilistic transformations of quantum states from a `source' set to a `target' set of states. Such transforms have many applications. They can be used for tasks which include state-dependent cloning or quantum state discrimination, and as interfaces between systems whose information encodings are not related by a unitary transform, such as continuous-variable systems and finite-dimensional systems. In a probabilistic transform, information may be lost or leaked, and we explain the concepts of leak and redundancy. Following this, we show how the analysis of probabilistic transforms significantly simplifies for symmetric source and target sets of states. In particular, we give a simple linear program which solves the task of finding optimal transforms, and a method of characterizing the introduced leak and redundancy in information-theoretic terms. Using the developed techniques, we analyse a class of transforms which convert coherent states with information encoded in their relative phase to symmetric qubit states. Each of these sets of states on their own appears in many well studied quantum information protocols. Finally, we suggest an asymptotic realization based on quantum scissors.

  18. {PT}-symmetrically deformed shock waves

    NASA Astrophysics Data System (ADS)

    Cavaglia, Andrea; Fring, Andreas

    2012-11-01

    We investigate for a large class of nonlinear wave equations, which allow for shock wave formations, how these solutions behave when they are {PT}-symmetrically deformed. For real solutions we find that they are transformed into peaked solutions with a discontinuity in the first derivative instead. The systems we investigate include the {PT}-symmetrically deformed inviscid Burgers equation recently studied by Bender and Feinberg, for which we show that it does not develop any shocks, but peaks instead. In this case we exploit the rare fact that the {PT}-deformation can be provided by an explicit map found by Curtright and Fairlie together with the property that the undeformed equation can be solved by the method of characteristics. We generalise the map and observe this type of behaviour for all integer values of the deformation parameter ?. The peaks are formed as a result of mapping the multi-valued self-avoiding shock profile to a multi-valued self-crossing function by means of the {PT}-deformation. For some deformation parameters we also investigate the deformation of complex solutions and demonstrate that in this case the deformation mechanism leads to discontinuities. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’.

  19. Analysis of non-symmetrical flapping airfoils

    NASA Astrophysics Data System (ADS)

    Tay, W. B.; Lim, K. B.

    2009-08-01

    Simulations have been done to assess the lift, thrust and propulsive efficiency of different types of non-symmetrical airfoils under different flapping configurations. The variables involved are reduced frequency, Strouhal number, pitch amplitude and phase angle. In order to analyze the variables more efficiently, the design of experiments using the response surface methodology is applied. Results show that both the variables and shape of the airfoil have a profound effect on the lift, thrust, and efficiency. By using non-symmetrical airfoils, average lift coefficient as high as 2.23 can be obtained. The average thrust coefficient and efficiency also reach high values of 2.53 and 0.61, respectively. The lift production is highly dependent on the airfoil’s shape while thrust production is influenced more heavily by the variables. Efficiency falls somewhere in between. Two-factor interactions are found to exist among the variables. This shows that it is not sufficient to analyze each variable individually. Vorticity diagrams are analyzed to explain the results obtained. Overall, the S1020 airfoil is able to provide relatively good efficiency and at the same time generate high thrust and lift force. These results aid in the design of a better ornithopter’s wing.

  20. PT-symmetric sine-Gordon breathers

    NASA Astrophysics Data System (ADS)

    Lu, Nan; Kevrekidis, Panayotis G.; Cuevas-Maraver, Jesús

    2014-11-01

    In this work, we explore a prototypical example of a genuine continuum breather (i.e., not a standing wave) and the conditions under which it can persist in a PT-symmetric medium. As our model of interest, we will explore the sine-Gordon equation in the presence of a PT-symmetric perturbation. Our main finding is that the breather of the sine-Gordon model will only persist at the interface between gain and loss that PT-symmetry imposes but will not be preserved if centered at the lossy or at the gain side. The latter dynamics is found to be interesting in its own right giving rise to kink–antikink pairs on the gain side and complete decay of the breather on the lossy side. Lastly, the stability of the breathers centered at the interface is studied. As may be anticipated on the basis of their ‘delicate’ existence properties such breathers are found to be destabilized through a Hopf bifurcation in the corresponding Floquet analysis.

  1. Integrable deformations of strings on symmetric spaces

    NASA Astrophysics Data System (ADS)

    Hollowood, Timothy J.; Miramontes, J. Luis; Schmidtt, David M.

    2014-11-01

    A general class of deformations of integrable sigma-models with symmetric space F/G target-spaces are found. These deformations involve defining the non-abelian T dual of the sigma-model and then replacing the coupling of the Lagrange multiplier imposing flatness with a gauged F/F WZW model. The original sigma-model is obtained in the limit of large level. The resulting deformed theories are shown to preserve both integrability and the equations-of-motion, but involve a deformation of the symplectic structure. It is shown that this deformed symplectic structure involves a linear combination of the original Poisson bracket and a generalization of the Faddeev-Reshetikhin Poisson bracket which we show can be re-expressed as two decoupled F current algebras. It is then shown that the deformation can be incorporated into the classical model of strings on via a generalization of the Pohlmeyer reduction. In this case, in the limit of large sigma-model coupling it is shown that the theory becomes the relativistic symmetric space sine-Gordon theory. These results point to the existence of a deformation of this kind for the full Green-Schwarz superstring on AdS5 × S 5.

  2. The modelling of symmetric airfoil vortex generators

    NASA Technical Reports Server (NTRS)

    Reichert, B. A.; Wendt, B. J.

    1996-01-01

    An experimental study is conducted to determine the dependence of vortex generator geometry and impinging flow conditions on shed vortex circulation and crossplane peak vorticity for one type of vortex generator. The vortex generator is a symmetric airfoil having a NACA 0012 cross-sectional profile. The geometry and flow parameters varied include angle-of-attack alfa, chordlength c, span h, and Mach number M. The vortex generators are mounted either in isolation or in a symmetric counter-rotating array configuration on the inside surface of a straight pipe. The turbulent boundary layer thickness to pipe radius ratio is delta/R = 0. 17. Circulation and peak vorticity data are derived from crossplane velocity measurements conducted at or about 1 chord downstream of the vortex generator trailing edge. Shed vortex circulation is observed to be proportional to M, alfa, and h/delta. With these parameters held constant, circulation is observed to fall off in monotonic fashion with increasing airfoil aspect ratio AR. Shed vortex peak vorticity is also observed to be proportional to M, alfa, and h/delta. Unlike circulation, however, peak vorticity is observed to increase with increasing aspect ratio, reaching a peak value at AR approx. 2.0 before falling off.

  3. Top 10 Nano & Chem Eng TMVogel, updated Fall 2012 Top 10 Things UCSD Nanoengineering &

    E-print Network

    Hampton, Randy

    Top 10 Nano & Chem Eng TMVogel, updated Fall 2012 Top 10 Things UCSD Nanoengineering & Chemical Engineering Researchers Need to Know http://libguides.ucsd.edu/nano http://libguides.ucsd.edu/chemeng http

  4. Playing with molecules.

    PubMed

    Toon, Adam

    2011-12-01

    Recent philosophy of science has seen a number of attempts to understand scientific models by looking to theories of fiction. In previous work, I have offered an account of models that draws on Kendall Walton's 'make-believe' theory of art. According to this account, models function as 'props' in games of make-believe, like children's dolls or toy trucks. In this paper, I assess the make-believe view through an empirical study of molecular models. I suggest that the view gains support when we look at the way that these models are used and the attitude that users take towards them. Users' interaction with molecular models suggests that they do imagine the models to be molecules, in much the same way that children imagine a doll to be a baby. Furthermore, I argue, users of molecular models imagine themselves viewing and manipulating molecules, just as children playing with a doll might imagine themselves looking at a baby or feeding it. Recognising this 'participation' in modelling, I suggest, points towards a new account of how models are used to learn about the world, and helps us to understand the value that scientists sometimes place on three-dimensional, physical models over other forms of representation. PMID:22332319

  5. The TOP-IMPLART project

    NASA Astrophysics Data System (ADS)

    Ronsivalle, C.; Carpanese, M.; Marino, C.; Messina, G.; Picardi, L.; Sandri, S.; Basile, E.; Caccia, B.; Castelluccio, D. M.; Cisbani, E.; Frullani, S.; Ghio, F.; Macellari, V.; Benassi, M.; D'Andrea, M.; Strigari, L.

    2011-07-01

    A new proton therapy center is planned to be built in Rome, Italy. The project, named TOP-IMPLART, is developed by three institutions, ENEA (Agenzia Nazionale per le Nuove tecnologie, l'Energia e lo Sviluppo Economico Sostenibile - Italian national agency for new technologies, energy and sustainable economic development), ISS (Istituto Superiore di Sanità, Italian National Institute of Health) and IFO-IRE (Istituto Fisioterapico Ospedaliero - Istituto Regina Elena, Regina Elena, National Cancer Institute in Rome). The project is centered on a medium-energy proton accelerator designed as a sequence of linear accelerators. Two phases of construction are foreseen: the first (funded by the Italian Regione Lazio for 11 M€ spread over four years) with a maximum energy of 150 MeV and the second one up to 230 MeV. The segment up to 150 MeV is under construction and will be tested at the ENEA Research Center in Frascati before the transfer to IFO that is the clinical user. The basic concepts of the design are described here.

  6. MHD Integrated Topping Cycle Project

    SciTech Connect

    Not Available

    1992-02-01

    This fourteenth quarterly technical progress report of the MHD Integrated Topping Cycle Project presents the accomplishments during the period November 1, 1990 to January 31, 1991. Testing of the High Pressure Cooling Subsystem electrical isolator was completed. The PEEK material successfully passed the high temperature, high pressure duration tests (50 hours). The Combustion Subsystem drawings were CADAM released. The procurement process is in progress. An equipment specification and RFP were prepared for the new Low Pressure Cooling System (LPCS) and released for quotation. Work has been conducted on confirmation tests leading to final gas-side designs and studies to assist in channel fabrication.The final cathode gas-side design and the proposed gas-side designs of the anode and sidewall are presented. Anode confirmation tests and related analyses of anode wear mechanisms used in the selection of the proposed anode design are presented. Sidewall confirmation tests, which were used to select the proposed gas-side design, were conducted. The design for the full scale CDIF system was completed. A test program was initiated to investigate the practicality of using Avco current controls for current consolidation in the power takeoff (PTO) regions and to determine the cause of past current consolidation failures. Another important activity was the installation of 1A4-style coupons in the 1A1 channel. A description of the coupons and their location with 1A1 channel is presented herein.

  7. Calculation of Symmetric Oligomer Structures from NMR Data

    Microsoft Academic Search

    Seán I. O’Donoghue; Michael Nilges

    The size range of proteins amenable to NMR spectroscopy has extended to the point where protein oligomer structures are now\\u000a being routinely determined. Many are symmetric; we found 36 symmetric oligomers solved by NMR in the present protein structure\\u000a database: 32 dimers, 2 tetramers, 1 pentamer, and 1 hexamer. Hence, we anticipate that an increasing number of symmetric oligomer\\u000a structures

  8. Search for top quark at Fermilab Collider

    SciTech Connect

    Sliwa, K. [Tufts Univ., Medford, MA (United States). Dept. of Physics; The CDF Collaboration

    1991-10-01

    The status of a search for the top quark with Collider Detector at Fermilab (CDF), based on a data sample recorded during the 1988--1989 run is presented. The plans for the next Fermilab Collider run in 1992--1993 and the prospects of discovering the top quark are discussed. 19 refs., 4 figs., 2 tabs.

  9. Top-k Set Similarity Joins

    Microsoft Academic Search

    Chuan Xiao; Wei Wang; Xuemin Lin; Haichuan Shang

    2009-01-01

    Similarity join is a useful primitive operation un- derlying many applications, such as near duplicate Web page detection, data integration, and pattern recognition. Traditiona l similarity joins require a user to specify a similarity threshold. In this paper, we study a variant of the similarity join, termed top-k set similarity join. It returns the top-k pairs of records ranked by

  10. CP violation in top-quark physics

    E-print Network

    German Valencia

    2010-07-27

    In this talk I review how to search for CP violation in top-quark pair production and decay using T-odd correlations. I discuss two examples which illustrate many of the relevant features: CP violation in a heavy neutral Higgs boson; and CP violating anomalous top-quark couplings. I present some numerical results for the LHC and some for the Tevatron.

  11. 7, 80878111, 2007 Influence of cloud top

    E-print Network

    Paris-Sud XI, Université de

    ACPD 7, 8087­8111, 2007 Influence of cloud top variability on radiative transfer Richter, Barfus under a Creative Commons License. Atmospheric Chemistry and Physics Discussions The influence of cloud.richter@awi.de) 8087 #12;ACPD 7, 8087­8111, 2007 Influence of cloud top variability on radiative transfer Richter

  12. Race to Top Draws out New Suitors

    ERIC Educational Resources Information Center

    McNeil, Michele

    2012-01-01

    The list of 61 finalists for the latest Race to the Top competition shows that the U.S. Department of Education was successful in enticing high-scoring applications from districts in rural America and in states that had not shared in the Race to the Top bounty before. But whether the ultimate winners, which will be announced this month, will be…

  13. World average top-quark mass

    SciTech Connect

    Glenzinski, D.; /Fermilab

    2008-01-01

    This paper summarizes a talk given at the Top2008 Workshop at La Biodola, Isola d Elba, Italy. The status of the world average top-quark mass is discussed. Some comments about the challanges facing the experiments in order to further improve the precision are offered.

  14. Top Stars: An Opportunity for Educators

    Microsoft Academic Search

    S. M. P. Kinnison

    2010-01-01

    Think you're a Top Star? Want to find out what it takes? Learn about NASA's Top Stars contest and how you can participate. Throughout its lifetime, the Hubble Space Telescope has inspired and promoted education. The final Hubble servicing mission in May of this year and the celebration of Hubble's 20th anniversary in 2010 are key mission milestones, and both

  15. Top 12 Web Resources for 2012

    ERIC Educational Resources Information Center

    Gonzales, Lisa; Vodicka, Devin

    2012-01-01

    In this article, the authors describe some of the top websites recommended by colleagues for the Association of California School Administrators. The Top 12 for 2012 are: (1) Facebook (facebook.com); (2) Twitter (twitter.com); (3) Tungle (tungle.me); (4) FCMAT (fcmat.org); (5) YouSendIt (yousendit.com); (6) Slideshare (slideshare.net); (7) QR…

  16. Technology Review: WBT Systems' TopClass.

    ERIC Educational Resources Information Center

    Szabo, Sharon

    1998-01-01

    Discusses TopClass, a Web-based tool and delivery system used for online courses, and its use at Schoolcraft College in Michigan. TopClass offers many benefits, including a self-contained management system, secured access, user-friendly instructions for coursework area creation, e-mail, bulletin boards, a secured testing mechanism and student…

  17. Annual Lists of Top Selling Toys

    NSDL National Science Digital Library

    To the great satisfaction of many, no doubt, Pokemon was not the top-seller in 1999, losing out to the old standards -- Crayola Crayons and Hot Wheels cars. In terms of dollar sales, however, another relative newcomer stood at the top -- Furby, but it was followed closely by Hot Wheels, a toy costing 1/33 the price.

  18. The Sakai Spinner: A Paperclip Top

    ERIC Educational Resources Information Center

    Corrao, Christian T.

    2014-01-01

    A challenge: Can you create a stable top from a single paper clip? Several interesting solutions to this problem were provided by Takao Sakai from Japan, the requirement of each being that the center of gravity be located on the vertical y-axis at the center of the top. In the simplest configuration, we see that there exists a single angle ?…

  19. 49 CFR 236.779 - Plate, top.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 2010-10-01 2010-10-01 false Plate, top. 236.779 Section 236.779 Transportation...AND APPLIANCES Definitions § 236.779 Plate, top. A metal plate secured to a locking bracket to prevent the cross locking from...

  20. Pinch Experiments in a Table Top Generator

    SciTech Connect

    Pavez, Cristian; Moreno, Jose; Soto, Leopoldo [Center for Research and Applications in Plasma Physics and Pulsed Power, P4 (Chile); Comision Chilena de Energia Nuclear (Chile); Tarifeno, Ariel [Center for Research and Applications in Plasma Physics and Pulsed Power, P4 (Chile); Universidad de Concepcion (Chile)

    2009-01-21

    The design and construction of a table top multipurpose capacitor bank of hundred of Joules and hundred of kiloAmperes conceived to be used in small scale Z-pinch experiments is reported. A recent result on a Z-pinch gas embedded discharge using hollow conical electrodes done in a similar table top generator is also presented.

  1. Entanglement equivalence of N-qubit symmetric states

    SciTech Connect

    Mathonet, P. [Departement de Mathematique, Universite de Liege, BE-4000 Liege (Belgium); Mathematics research unit, FSTC, University of Luxembourg, L-1359 Luxembourg (Luxembourg); Krins, S.; Bastin, T. [Institut de Physique Nucleaire, Atomique et de Spectroscopie, Universite de Liege, BE-4000 Liege (Belgium); Godefroid, M. [Chimie quantique et Photophysique, CP160/09, Universite Libre de Bruxelles, BE-1050 Bruxelles (Belgium); Lamata, L. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, DE-85748 Garching (Germany); Solano, E. [Departamento de Quimica Fisica, Universidad del Pais Vasco - Euskal Herriko Unibertsitatea, Apdo. 644, ES-48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, Alameda Urquijo 36, ES-48011 Bilbao (Spain)

    2010-05-15

    We study the interconversion of multipartite symmetric N-qubit states under stochastic local operations and classical communication (SLOCC). We demonstrate that if two symmetric states can be connected with a nonsymmetric invertible local operation (ILO), then they belong necessarily to the separable, W, or Greenberger-Horne-Zeilinger (GHZ) entanglement class, establishing a practical method of discriminating subsets of entanglement classes. Furthermore, we prove that there always exists a symmetric ILO connecting any pair of symmetric N-qubit states equivalent under SLOCC, simplifying the requirements for experimental implementations of local interconversion of those states.

  2. D{O} top quark mass analysis

    SciTech Connect

    Strovink, M.

    1995-07-01

    Based on (44-48 pb{sup -1}) of lepton + jets data, we review D0`s initial analysis of the top quark mass. The result, M{sub top} = 199 {+-} 19/21 (stat.) {+-} 22 (syst.) GeV/c{sup 2}, is insensitive to background normalization. The errors are based on ISAJET top Monte Carlo, with its more severe gluon radiation, and allow for ISAJET/HERWIG differences. Good progress is being made in reducing the systematic error. We present a new study based on two-dimensional distributions of reconstructed top quark vs. dijet mass. With 98.7% confidence we observe a peak in the top mass - dijet mass plane. The peak and its projections are similar both in shape and magnitude to expectations based on the decay sequence 1 {yields} bW, W {yields} jj.

  3. Protein Identification Using Top-Down

    SciTech Connect

    Liu, Xiaowen; Sirotkin, Yakov; Shen, Yufeng; Anderson, Gordon A.; Tsai, Yi-Hsuan S.; Ting, Ying S.; Goodlett, David R.; Smith, Richard D.; Bafna, Vineet; Pevzner, Pavel A.

    2012-06-01

    In the last two years, due to advances in protein separation and mass spectrometry, top-down mass spectrometry moved from analyzing single proteins to analyzing complex samples and identifying hundreds and even thousands of proteins. However, computational tools for database search of top-down spectra against protein databases are still in infancy. We describe MS-Align+, a fast algorithm for top-down protein identification based on spectral alignment that enables searches for unexpected post-translational modifications (PTMs). We also propose a method for evaluating statistical significance of top-down protein identifications and further benchmark MS-Align+ along with PIITA, ProSightPTM and SEQUEST, which were previously used for top-down MS/MS database searches. We demonstrate that MS-Align+ and PIITA significantly increase the number of identified proteins as compared to ProSightPTM and SEQUEST.

  4. Thermionic topping of electric power plants

    NASA Technical Reports Server (NTRS)

    Britt, E. J.; Fitzpatrick, G. O.; Rasor, N. S.

    1975-01-01

    The most likely use of thermionic conversion is in the form of a topping cycle combined with a steam-turbogenerator plant. A specific reference system is chosen in which the thermionic topping cycle occurs in thermionic heat exchangers referred to as large, modular thermionic units to which heat is transferred from a separate heat source and which reject their heat to a conventional steam turboelectric system. Results of analysis show that the performance and cost criteria for practical thermionic topping of large electric power plants are well within the reach of demonstrated and foreseeable converter capabilities. Thermionic topping has many significant advantages over unconventional cycles proposed for topping applications, including level of demonstrated and projected performance and lifetime, development time, and design simplicity.

  5. TOP500 Supercomputers for June 2002

    SciTech Connect

    Strohmaier, Erich; Meuer, Hans W.; Dongarra, Jack; Simon, Horst D.

    2002-06-20

    19th Edition of TOP500 List of World's Fastest Supercomputers Released MANNHEIM, Germany; KNOXVILLE, Tenn.;&BERKELEY, Calif. In what has become a much-anticipated event in the world of high-performance computing, the 19th edition of the TOP500 list of the worlds fastest supercomputers was released today (June 20, 2002). The recently installed Earth Simulator supercomputer at the Earth Simulator Center in Yokohama, Japan, is as expected the clear new number 1. Its performance of 35.86 Tflop/s (trillions of calculations per second) running the Linpack benchmark is almost five times higher than the performance of the now No.2 IBM ASCI White system at Lawrence Livermore National Laboratory (7.2 Tflop/s). This powerful leap frogging to the top by a system so much faster than the previous top system is unparalleled in the history of the TOP500.

  6. Structure and dynamics of C60 molecules on Au(111)

    SciTech Connect

    Shin, Heekeun [Penn State University; Schwarze, A [Penn State University; Diehl, R D [Penn State University; Pussi, K [Lappeenranta University of Technology; Colombier, A [Universite de Lorraine; Gaudry, E. [Universite de Lorraine; Ledieu, J [Universite de Lorraine; McGuirk, G M [Universite de Lorraine; Serkovic Loli, L N [Universite de Lorraine; Fournee, V [Universite de Lorraine; Wang, Lin-Lin [Ames Laboratory; Schull, G [Universite de Strasbourg; Berndt, R [Christian-Albrechts-Universitt zu Kiel

    2014-06-01

    Earlier studies of C60 adsorption on Au(111) reported many interesting and complex features. We have performed coordinated low-energy electron diffraction, scanning tunneling microscopy (STM), and density functional theory studies to elucidate some of the details of the monolayer commensurate (2?3 × 2?3)R30° phase. We have identified the adsorption geometries of the two states that image as dim and bright in STM. These consist of a C60 molecule with a hexagon side down in a vacancy (hex-vac) and a C60 molecule with a carbon-carbon 6:6 bond down on a top site (6:6-top), respectively. We have studied the detailed geometries of these states and find that there is little distortion of the C60 molecules, but there is a rearrangement of the substrate near the C60 molecules. The two types of molecules differ in height, by about 0.7 Å, which accounts for most of the difference in their contrast in the STM images. The monolayer displays dynamical behavior, in which the molecules flip from bright to dim, and vice versa. We interpret this flipping as the result of the diffusion of vacancies in the surface layers of the substrate. Our measurements of the dynamics of this flipping from one state to the other indicate that the activation energy is 0.66 ± 0.03 eV for flips that involve nearest-neighbor C60 molecules, and 0.93 ± 0.03 for more distant flips. Based on calculated activation energies for vacancies diffusing in Au, we interpret these to be a result of surface vacancy diffusion and bulk vacancy diffusion. These results are compared to the similar system of Ag(111)-(2?3 × 2?3)R30°-C60. In both systems, the formation of the commensurate C60 monolayer produces a large number of vacancies in the top substrate layer that are highly mobile, effectively melting the interfacial metal layer at temperatures well below their normal melting temperatures.

  7. Build a DNA Molecule

    NSDL National Science Digital Library

    How does a DNA molecule grow? This is a key question for budding geneticists, and one that is eloquently answered via this online activity, offered courtesy of the Genetic Science Learning Center at the University of Utah. The site uses an elegant animation to show interested parties how DNA is copied every day and each time a new cell divides. Visitors can read about this process or they can just click on the Start Building tab to move various bits and pieces around to understand the world of DNA base pairs and such. Also, the site includes animations of DNA replications from the Howard Hughes Medical Institute's Biointeractive site and a comparison of the size of a nucleotide to other objects. Overall, it's a great resource for those with an interest in learning more about this most integral aspect of genetics.

  8. Molecules in the Spotlight

    SciTech Connect

    Cryan, James

    2010-01-26

    SLAC has just unveiled the world's first X-ray laser, the LCLS. This machine produces pulses of X-rays that are ten billion times brighter than those from conventional sources. One of the goals of this machine is to make movies of chemical reactions, including reactions necessary for life and reactions that might power new energy technologies. This public lecture will show the first results from the LCLS. As a first target, we have chosen nitrogen gas, the main component of the air we breathe. Using the unprecedented power of the LCLS X-rays as a blasting torch, we have created new forms of this molecule and with unique electronic arrangements. Please share with us the first insights from this new technology.

  9. Single molecule laser spectroscopy.

    PubMed

    Atta, Diaa; Okasha, Ali

    2015-01-25

    In this article, we discussed some single molecule spectroscopy techniques and methods. We have chosen the simplicity in this survey based on our laboratory experience in this field. We concentrated on the imaging by both techniques the wide field and the scanning microscopes. Other imaging enhancements on the technique like extended resolution wide field, the total internal reflection imaging, and its derivatives are also reviewed. In addition to the imaging techniques, some diffusion techniques also are discussed like fluorescence correlation spectroscopy. The related methods like Forester resonance transfer, photo-induced electron transfer and anisotropy (steady state and time decay) are also discussed. In addition, we elucidated some simple details about the theory behind the FCS and its resulting curve fitting. This review is preceded by general introduction and ended with the conclusion. PMID:25156641

  10. Single molecule laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Atta, Diaa; Okasha, Ali

    2015-01-01

    In this article, we discussed some single molecule spectroscopy techniques and methods. We have chosen the simplicity in this survey based on our laboratory experience in this field. We concentrated on the imaging by both techniques the wide field and the scanning microscopes. Other imaging enhancements on the technique like extended resolution wide field, the total internal reflection imaging, and its derivatives are also reviewed. In addition to the imaging techniques, some diffusion techniques also are discussed like fluorescence correlation spectroscopy. The related methods like Forester resonance transfer, photo-induced electron transfer and anisotropy (steady state and time decay) are also discussed. In addition, we elucidated some simple details about the theory behind the FCS and its resulting curve fitting. This review is preceded by general introduction and ended with the conclusion.

  11. Forces in molecules.

    PubMed

    Hernández-Trujillo, Jesús; Cortés-Guzmán, Fernando; Fang, De-Chai; Bader, Richard F W

    2007-01-01

    Chemistry is determined by the electrostatic forces acting within a collection of nuclei and electrons. The attraction of the nuclei for the electrons is the only attractive force in a molecule and is the force responsible for the bonding between atoms. This is the attractive force acting on the electrons in the Ehrenfest force and on the nuclei in the Feynman force, one that is countered by the repulsion between the electrons in the former and by the repulsion between the nuclei in the latter. The virial theorem relates these forces to the energy changes resulting from interactions between atoms. All bonding, as signified by the presence of a bond path, has a common origin in terms of the mechanics determined by the Ehrenfest, Feynman and virial theorems. This paper is concerned in particular with the mechanics of interaction encountered in what are classically described as 'nonbonded interactions'--are atoms that 'touch' bonded or repelling one another? PMID:17328425

  12. Quantum searches on highly symmetric graphs

    NASA Astrophysics Data System (ADS)

    Reitzner, Daniel; Hillery, Mark; Feldman, Edgar; Bužek, Vladimír

    2009-01-01

    We study scattering quantum walks on highly symmetric graphs and use the walks to solve search problems on these graphs. The particle making the walk resides on the edges of the graph, and at each time step scatters at the vertices. All of the vertices have the same scattering properties except for a subset of special vertices. The object of the search is to find a special vertex. A quantum circuit implementation of these walks is presented in which the set of special vertices is specified by a quantum oracle. We consider the complete graph, a complete bipartite graph, and an M -partite graph. In all cases, the dimension of the Hilbert space in which the time evolution of the walk takes place is small (between three and six), so the walks can be completely analyzed analytically. Such dimensional reduction is due to the fact that these graphs have large automorphism groups. We find the usual quadratic quantum speedups in all cases considered.

  13. Expanding Spherically Symmetric Models without Shear

    E-print Network

    Sunil D Maharaj; Peter GL Leach; Roy Maartens

    1995-11-27

    The integrability properties of the field equation $L_{xx} = F(x)L^2$ of a spherically symmetric shear--free fluid are investigated. A first integral, subject to an integrability condition on $F(x)$, is found, giving a new class of solutions which contains the solutions of Stephani (1983) and Srivastava (1987) as special cases. The integrability condition on $F(x)$ is reduced to a quadrature which is expressible in terms of elliptic integrals in general. There are three classes of solution and in general the solution of $L_{xx} = F(x)L^2$ can only be written in parametric form. The case for which $F=F(x)$ can be explicitly given corresponds to the solution of Stephani (1983). A Lie analysis of $L_{xx} = F(x) L^2$ is also performed. If a constant $\\alpha$ vanishes, then the solutions of Kustaanheimo and Qvist (1948) and of this paper are regained. For $\\alpha \

  14. Circularly symmetric light scattering from nanoplasmonic spirals.

    PubMed

    Trevino, Jacob; Cao, Hui; Dal Negro, Luca

    2011-05-11

    In this paper, we combine experimental dark-field imaging, scattering, and fluorescence spectroscopy with rigorous electrodynamics calculations in order to investigate light scattering from planar arrays of Au nanoparticles arranged in aperiodic spirals with diffuse, circularly symmetric Fourier space. In particular, by studying the three main types of Vogel's spirals fabricated by electron-beam lithography on quartz substrates, we demonstrate polarization-insensitive planar light diffraction in the visible spectral range. Moreover, by combining dark-field imaging with analytical multiparticle calculations in the framework of the generalized Mie theory, we show that plasmonic spirals support distinctive structural resonances with circular symmetry carrying orbital angular momentum. The engineering of light scattering phenomena in deterministic structures with circular Fourier space provides a novel strategy for the realization of optical devices that fully leverage on enhanced, polarization-insensitive light-matter coupling over planar surfaces, such as thin-film plasmonic solar cells, plasmonic polarization devices, and optical biosensors. PMID:21466155

  15. Hamiltonian theory of symmetric optical network transforms

    NASA Astrophysics Data System (ADS)

    Törmä, Päivi; Stenholm, Stig

    1995-12-01

    We discuss the theory of extracting an interaction Hamiltonian from a preassigned unitary transformation of quantum states. Such a procedure is of significance in quantum computations and other optical information processing tasks. We particularize the problem to the construction of totally symmetric 2N ports as introduced by Zeilinger and his collaborators [A. Zeilinger, M. Zukowski, M. A. Horne, H. J. Bernstein, and D. M. Greenberger, in Fundamental Aspects of Quantum Theory, edited by J. Anandan and J. J. Safko (World Scientific, Singapore, 1994)]. These are realized by the discrete Fourier transform, which simplifies the construction of the Hamiltonian by known methods of linear algebra. The Hamiltonians found are discussed and alternative realizations of the Zeilinger class transformations are presented. We briefly discuss the applicability of the method to more general devices.

  16. Symmetrized characterization of noisy quantum processes.

    PubMed

    Emerson, Joseph; Silva, Marcus; Moussa, Osama; Ryan, Colm; Laforest, Martin; Baugh, Jonathan; Cory, David G; Laflamme, Raymond

    2007-09-28

    A major goal of developing high-precision control of many-body quantum systems is to realize their potential as quantum computers. A substantial obstacle to this is the extreme fragility of quantum systems to "decoherence" from environmental noise and other control limitations. Although quantum computation is possible if the noise affecting the quantum system satisfies certain conditions, existing methods for noise characterization are intractable for present multibody systems. We introduce a technique based on symmetrization that enables direct experimental measurement of some key properties of the decoherence affecting a quantum system. Our method reduces the number of experiments required from exponential to polynomial in the number of subsystems. The technique is demonstrated for the optimization of control over nuclear spins in the solid state. PMID:17901327

  17. Cylindrically Symmetric Models of Anisotropic Compact Stars

    E-print Network

    G. Abbas; Sumara Nazeer; M. A. Meraj

    2014-12-16

    In this paper we have discussed the possibility of forming anisotropic compact stars from cosmological constant as one of the competent candidates of dark energy with cylindrical symmetry. For this purpose, we have applied the analytical solution of Krori and Barua metric to a particular cylindrically symmetric spacetime. The unknown constants in Krori and Barua metric have been determined by using masses and radii of class of compact stars like 4$U$1820-30, Her X-1, SAX J 1808-3658. The properties of these stars have been analyzed in detail. In this setting the cosmological constant has been taken as a variable which depends on the radial coordinates. We have checked all the regularity conditions, stability and surface redshift of the compact stars 4$U$1820-30, Her X-1, SAX J 1808-3658.

  18. Acoustic horizons in axially symmetric relativistic accretion

    E-print Network

    Hrvoje Abraham; Neven Bilic; Tapas K. Das

    2006-04-26

    Transonic accretion onto astrophysical objects is a unique example of analogue black hole realized in nature. In the framework of acoustic geometry we study axially symmetric accretion and wind of a rotating astrophysical black hole or of a neutron star assuming isentropic flow of a fluid described by a polytropic equation of state. In particular we analyze the causal structure of multitransonic configurations with two sonic points and a shock. Retarded and advanced null curves clearly demonstrate the presence of the acoustic black hole at regular sonic points and of the white hole at the shock. We calculate the analogue surface gravity and the Hawking temperature for the inner and the outer acoustic horizons.

  19. Pseudo-Z symmetric space-times

    SciTech Connect

    Mantica, Carlo Alberto, E-mail: carloalberto.mantica@libero.it [Physics Department, Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Suh, Young Jin, E-mail: yjsuh@knu.ac.kr [Department of Mathematics, Kyungpook National University, Taegu 702-701 (Korea, Republic of)

    2014-04-15

    In this paper, we investigate Pseudo-Z symmetric space-time manifolds. First, we deal with elementary properties showing that the associated form A{sub k} is closed: in the case the Ricci tensor results to be Weyl compatible. This notion was recently introduced by one of the present authors. The consequences of the Weyl compatibility on the magnetic part of the Weyl tensor are pointed out. This determines the Petrov types of such space times. Finally, we investigate some interesting properties of (PZS){sub 4} space-time; in particular, we take into consideration perfect fluid and scalar field space-time, and interesting properties are pointed out, including the Petrov classification. In the case of scalar field space-time, it is shown that the scalar field satisfies a generalized eikonal equation. Further, it is shown that the integral curves of the gradient field are geodesics. A classical method to find a general integral is presented.

  20. Geranyl diphosphate synthase molecules, and nucleic acid molecules encoding same

    DOEpatents

    Croteau, Rodney Bruce (Pullman, WA); Burke, Charles Cullen (Moscow, ID)

    2008-06-24

    In one aspect, the present invention provides isolated nucleic acid molecules that each encode a geranyl diphosphate synthase protein, wherein each isolated nucleic acid molecule hybridizes to a nucleic acid molecule consisting of the sequence set forth in SEQ ID NO:1 under conditions of 5.times.SSC at 45.degree. C. for one hour. The present invention also provides isolated geranyl diphosphate synthase proteins, and methods for altering the level of expression of geranyl diphosphate synthase protein in a host cell.

  1. Electron-excited molecule interactions

    SciTech Connect

    Christophorou, L.G. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA). Dept. of Physics)

    1991-01-01

    In this paper the limited but significant knowledge to date on electron scattering from vibrationally/rotationally excited molecules and electron scattering from and electron impact ionization of electronically excited molecules is briefly summarized and discussed. The profound effects of the internal energy content of a molecule on its electron attachment properties are highlighted focusing in particular on electron attachment to vibrationally/rotationally and to electronically excited molecules. The limited knowledge to date on electron-excited molecule interactions clearly shows that the cross sections for certain electron-molecule collision processes can be very different from those involving ground state molecules. For example, optically enhanced electron attachment studies have shown that electron attachment to electronically excited molecules can occur with cross sections 10{sup 6} to 10{sup 7} times larger compared to ground state molecules. The study of electron-excited molecule interactions offers many experimental and theoretical challenges and opportunities and is both of fundamental and technological significance. 54 refs., 15 figs.

  2. Discovery of single top quark production

    SciTech Connect

    Gillberg, Dag

    2009-05-01

    The top quark is by far the heaviest known fundamental particle with a mass nearing that of a gold atom. Because of this strikingly high mass, the top quark has several unique properties and might play an important role in electroweak symmetry breaking - the mechanism that gives all elementary particles mass. Creating top quarks requires access to very high energy collisions, and at present only the Tevatron collider at Fermilab is capable of reaching these energies. Until now, top quarks have only been observed produced in pairs via the strong interaction. At hadron colliders, it should also be possible to produce single top quarks via the electroweak interaction. Studies of single top quark production provide opportunities to measure the top quark spin, how top quarks mix with other quarks, and to look for new physics beyond the standard model. Because of these interesting properties, scientists have been looking for single top quarks for more than 15 years. This thesis presents the first discovery of single top quark production. An analysis is performed using 2.3 fb{sup -1} of data recorded by the D0 detector at the Fermilab Tevatron Collider at centre-of-mass energy {radical}s = 1.96 TeV. Boosted decision trees are used to isolate the single top signal from background, and the single top cross section is measured to be {sigma}(p{bar p} {yields} tb + X, tqb + X) = 3.74{sub -0.74}{sup +0.95} pb. Using the same analysis, a measurement of the amplitude of the CKM matrix element V{sub tb}, governing how top and b quarks mix, is also performed. The measurement yields: |V{sub tb}|f{sub 1}{sup L}| = 1.05{sub -0.12}{sup +0.13}, where f{sub 1}{sup L} is the left-handed Wtb coupling. The separation of signal from background is improved by combining the boosted decision trees with two other multivariate techniques. A new cross section measurement is performed, and the significance for the excess over the predicted background exceeds 5 standard deviations.

  3. Accurate photometry of extended spherically symmetric sources

    NASA Astrophysics Data System (ADS)

    Anders, P.; Gieles, M.; de Grijs, R.

    2006-05-01

    We present a new method to derive reliable photometry of extended spherically symmetric sources from HST images (WFPC2, ACS/WFC and NICMOS/NIC2 cameras), extending existing studies of point sources and marginally resolved sources. We develop a new approach to accurately determine intrinsic sizes of extended spherically symmetric sources, such as star clusters in galaxies beyond the Local Group (at distances ?20 Mpc), and provide a detailed cookbook to perform aperture photometry on such sources, by determining size-dependent aperture corrections (ACs) and taking sky oversubtraction as a function of source size into account. In an extensive Appendix, we provide the parameters of polynomial relations between the FWHM of various input profiles and those obtained by fitting a Gaussian profile (which we have used for reasons of computational robustness, although the exact model profile used is irrelevant), and between the intrinsic and measured FWHM of the cluster and the derived AC. Both relations are given for a number of physically relevant cluster light profiles, intrinsic and observational parameters. AC relations are provided for a wide range of apertures. Depending on the size of the source and the annuli used for the photometry, the absolute magnitude of such extended objects can be underestimated by up to 3 mag, corresponding to an error in mass of a factor of 15. We carefully compare our results to those from the more widely used DeltaMag method, and find an improvement of a factor of 3-40 in both the size determination and the AC.

  4. Duality Symmetric String and M-Theory

    E-print Network

    David S. Berman; Daniel C. Thompson

    2014-12-09

    We review recent developments in duality symmetric string theory. We begin with the world sheet doubled formalism which describes strings in an extended space time with extra coordinates conjugate to winding modes. This formalism is T-duality symmetric and can accommodate non-geometric T-fold backgrounds which are beyond the scope of Riemannian geometry. Vanishing of the conformal anomaly of this theory can be interpreted as a set of spacetime equations for the background fields. These equations follow from an action principle that has been dubbed Double Field Theory (DFT). We review the aspects of generalised geometry relevant for DFT. We outline recent extensions of DFT and explain how, by relaxing the so-called strong constraint with a Scherk Schwarz ansatz, one can obtain backgrounds that simultaneously depend on both the regular and T-dual coordinates. This provides a purely geometric higher dimensional origin to gauged supergravities that arise from non-geometric compactification. We then turn to M-theory and describe recent progress in formulating an E_{n(n)} U-duality covariant description of the dynamics. We describe how spacetime may be extended to accommodate coordinates conjugate to brane wrapping modes and the construction of generalised metrics in this extend space that unite the bosonic fields of supergravity into a single object. We review the action principles for these theories and their novel gauge symmetries. We also describe how a Scherk Schwarz reduction can be applied in the M-theory context and the resulting relationship to the embedding tensor formulation of maximal gauged supergravities.

  5. Device engineering for highly efficient top-illuminated organic solar cells with microcavity structures.

    PubMed

    Lin, Hao-Wu; Chiu, Si-Wen; Lin, Li-Yen; Hung, Zheng-Yu; Chen, Yi-Hong; Lin, Francis; Wong, Ken-Tsung

    2012-05-01

    Small-molecule organic solar cells with microcavity structures utilizing very thin solar-absorbing active layers are simulated and fabricated. By carefully fine-tuning the in-cell spacer layer and out-of-cell capping layer, highly efficient top-illuminated indium tin oxide-free solar cells are created on glass and flexible polyethylene terephthalate substrates with efficiencies of up to 5.5% and 5%, respectively. PMID:22473611

  6. Langevin equations and computed correlation functions for a rotating and translating asymmetric top

    Microsoft Academic Search

    M. W. Evans; G. J. Evans

    1986-01-01

    The three-dimensional diffusion in condensed material of a rotating and translating asymmetric-top molecule is considered with use of three frames of reference: the laboratory frame (x,y,z), a rotating frame (1,2,3)', and a moving frame (1,2,3). The frame (1,2,3)' has the same origin as (x,y,z), but rotates with an angular velocity omega, the molecular angular velocity. The frame (1,2,3) is defined

  7. Vibrational energy transfer in ultracold molecule - molecule collisions

    E-print Network

    Goulven Quéméner; Naduvalath Balakrishnan; Roman V. Krems

    2008-01-15

    We present a rigorous study of vibrational relaxation in p-H2 + p-H2 collisions at cold and ultracold temperatures and identify an efficient mechanism of ro-vibrational energy transfer. If the colliding molecules are in different rotational and vibrational levels, the internal energy may be transferred between the molecules through an extremely state-selective process involving simultaneous conservation of internal energy and total rotational angular momentum. The same transition in collisions of distinguishable molecules corresponds to the rotational energy transfer from one vibrational state of the colliding molecules to another.

  8. Coherent perfect absorption in one-dimensional photonic crystal with a PT-symmetric defect

    NASA Astrophysics Data System (ADS)

    Zhang, Zheng-Ren; Li, Hong-Qiang; Chen, Hong; Hu, Chun-Lian; Zhou, Ping

    2014-02-01

    In this paper, we demonstrate a one-dimensional photonic crystal defect mode coherent perfect absorber (CPA) or antilasing, which is based on the PT-synthetic material defect. It is found that the CPA can be excited by two coherent monochromatic waves which are located at the frequency range of the defect mode (near the top of the transmission peak in the gap) incident with the same amplitude from both sides. Moreover, we found that the CPA frequency possesses the property of flexible controllability. This property can easily be realized by modulating the variation in thickness of the defect layer and the symmetrical incidence angle of the two coherent beams. Therefore, the photonic crystal defect mode CPA proposed here shows much more flexibility in operation frequency compared with the results in the literature (Chong Y. D. et al., Phys. Rev. Lett., 105 (2010) 053901; Wan W. et al., Science, 331 (2011) 889).

  9. Multiple optical trapping based on high-order axially symmetric polarized beams

    NASA Astrophysics Data System (ADS)

    Zhou, Zhe-Hai; Zhu, Lian-Qing

    2015-02-01

    Multiple optical trapping with high-order axially symmetric polarized beams (ASPBs) is studied theoretically, and a scheme based on far-field optical trapping with ASPBs is first proposed. The focused fields and the corresponding gradient forces on Rayleigh dielectric particles are calculated for the scheme. The calculated results indicate that multiple ultra-small focused spots can be achieved, and multiple nanometer-sized particles with refractive index higher than the ambient can be trapped simultaneously near these focused spots, which are expected to enhance the capabilities of traditional optical trapping systems and provide a solution for massive multiple optical trapping of nanometer-sized particles. Project supported by the National Natural Science Foundation of China (Grant Nos. 61108047 and 61475021), the Program for New Century Excellent Talents in University, China (Grant No. NCET-13-0667), and the Beijing Top Young Talents Support Program, China (Grant No. CIT&TCD201404113).

  10. SelInv - An Algorithm for Selected Inversion of a Sparse Symmetric Matrix

    SciTech Connect

    Lin, Lin; Yang, Chao; Meza, Juan C.; Lu, Jianfeng; Ying, Lexing; E, Weinan

    2009-10-16

    We describe an efficient implementation of an algorithm for computing selected elements of a general sparse symmetric matrix A that can be decomposed as A = LDL^T, where L is lower triangular and D is diagonal. Our implementation, which is called SelInv, is built on top of an efficient supernodal left-looking LDL^T factorization of A. We discuss how computational efficiency can be gained by making use of a relative index array to handle indirect addressing. We report the performance of SelInv on a collection of sparse matrices of various sizes and nonzero structures. We also demonstrate how SelInv can be used in electronic structure calculations.

  11. Rectangular symmetrical mesa beams and their comparison with flattened Gaussian and multi-Gaussian beams

    NASA Astrophysics Data System (ADS)

    Sedukhin, Andrey G.

    2015-01-01

    A two-component analytical model describing 1D, paraxial, rectangular symmetrical mesa beams of arbitrary fractional orders is proposed. Such beams possess a plane wavefront and flat-topped intensity profiles at their waists. It is shown that they are reasonably well matched with 1D flattened Gaussian and generalized multi-Gaussian beams described by more complicated models in the form of finite superpositions of an on-axis fundamental Gaussian mode mixed, respectively, either with on-axis, 1D, elegant Hermite-Gaussian modes of higher orders or with off-axis fundamental Gaussian modes. A procedure of exact optimization fitting, the main propagation characteristics and the modal content of all the above beams are considered in detail. The proposed model is shown to have the most compact and convenient mathematical description of the beams and their characteristics.

  12. Multi-tops at the LHC

    NASA Astrophysics Data System (ADS)

    Deandrea, Aldo; Deutschmann, Nicolas

    2014-08-01

    The experiments at the LHC are searching for many different final states that can hint to the presence of new physics beyond the Standard Model. One of the most interesting and promising sectors for these searches is that of the top quark, for both theoretical and phenomenological reasons linked to its large mass and to its possible special role in the electroweak symmetry breaking sector. We suggest that multi-top events, beyond the standard and four top searches, can bring further insight in constraining and discovering physics beyond the Standard Model, taking advantage of experimental techniques similar to those used in present top-quark analyses. This is relevant both for the next data taking runs at the LHC and even more at higher luminosity and higher energy collider options, which are discussed for future LHC upgrades and future accelerators. In particular we consider six top and eight top final states, discussing the generic colour representations for beyond the Standard Model particles giving rise to those final state. We also discuss the limits which can be extracted by using the present analyses sensitive to four top final states, as well as the potential bounds from new searches we propose to experimental collaborations as an alternative.

  13. Electric top drives gain wide industry acceptance

    SciTech Connect

    Riahi, M.L.

    1998-05-01

    Since its introduction, the top drive drilling system has gained acceptance as a productive and safe method for drilling oil and gas wells. Originally, the system was used mostly for offshore and higher cost land drilling, and it had to be installed as a permanent installation because of its enormous weight and size. Essentially, a top drive replaces the kelly and rotary table as the means of rotating drillpipe on oil, gas and geothermal rigs and is considered to be 15% to 40% more efficient than a kelly drive. Top drive systems allow the operator to drill and maintain directional orientation for triple stands and provide tripping efficiency because of the ability to ream and circulate with triple stands, to reduce the risk of stuck pipe or lost wells, and to improve well control and pipe handling safety. The paper describes electric top drives with DC motors, top drives with AC motors, top drives with permanent magnet motors, and top drives with permanent magnet brushless synchronous motors.

  14. THE TOP QUARK, QCD, AND NEW PHYSICS.

    SciTech Connect

    DAWSON,S.

    2002-06-01

    The role of the top quark in completing the Standard Model quark sector is reviewed, along with a discussion of production, decay, and theoretical restrictions on the top quark properties. Particular attention is paid to the top quark as a laboratory for perturbative QCD. As examples of the relevance of QCD corrections in the top quark sector, the calculation of e{sup +}e{sup -} + t{bar t} at next-to-leading-order QCD using the phase space slicing algorithm and the implications of a precision measurement of the top quark mass are discussed in detail. The associated production of a t{bar t} pair and a Higgs boson in either e{sup +}e{sup -} or hadronic collisions is presented at next-to-leading-order QCD and its importance for a measurement of the top quark Yulrawa coupling emphasized. Implications of the heavy top quark mass for model builders are briefly examined, with the minimal supersymmetric Standard Model and topcolor discussed as specific examples.

  15. Deuterium in North Atlantic storm tops

    NASA Technical Reports Server (NTRS)

    Smith, Ronald B.

    1992-01-01

    During the ERICA project in 1989, ice crystals were collected from the tops of two winter storms and one broad cirrus cloud. Deuterium concentration in the storm ice samples, together with a model of isotope fractionation, are used to determine the temperature where the ice was formed. Knowledge of the ice formation temperature allows us to determine whether the ice has fallen or been lofted to the altitude of collection. In both storms, the estimated fall distance decreases upward. In the 21 January storm, the fall distance decreases to zero at the cloud top. In the 23 January storm, the fall distance decreases to zero at a point 2 km below the cloud top and appears to become negative above, indicating lofted ice. Cloud particle data from the cloud tops show an ice-to-vapor ratio greater than one and indicate the presence of particles with small terminal velocities; both observations support the idea of ice lofting. The satellite-derived cloud tops lie well below the actual cloud top (e.g., 2.5 km below on 23 January), indicating that the lofted ice in winter storms may not be detectable from space using IR radiance techniques. A comparison of deuterium in cloud-top ice and clear-air vapor suggests that even in winter, when vertical air motions are relatively weak, lofted ice crystals are the dominant source of water vapor in the upper troposphere.

  16. Synthesis and Physical Properties of Symmetrical and Non-symmetrical Triacylglycerols Containing Two Palmitic Fatty Acids

    Microsoft Academic Search

    R. O. Adlof; G. R. List

    2008-01-01

    A series of symmetrical (ABA) and non-symmetrical (AAB) triacylglycerol (TAG) isomers containing “A,” palmitic (P; 16:0) acid,\\u000a and “B,” either oleic (O; 9c-18:1), elaidic (E; 9t-18:1), linoleic (L; 9c,12c-18:2) or linolenic (Ln; 9c,12c,15c-18:3) fatty\\u000a acids were synthesized by esterification of the thermodynamically more-stable 1,3-di- or 1(3)-monoacylglycerols [1,3-DAG or\\u000a 1(3)-MAG], respectively. 1,3-dipalmitoylglycerol (1,3P-DAG) was esterified with O, L or Ln acid

  17. Towards single molecule DNA sequencing

    NASA Astrophysics Data System (ADS)

    Liu, Hao

    Single molecule DNA Sequencing technology has been a hot research topic in the recent decades because it holds the promise to sequence a human genome in a fast and affordable way, which will eventually make personalized medicine possible. Single molecule differentiation and DNA translocation control are the two main challenges in all single molecule DNA sequencing methods. In this thesis, I will first introduce DNA sequencing technology development and its application, and then explain the performance and limitation of prior art in detail. Following that, I will show a single molecule DNA base differentiation result obtained in recognition tunneling experiments. Furthermore, I will explain the assembly of a nanofluidic platform for single strand DNA translocation, which holds the promised to be integrated into a single molecule DNA sequencing instrument for DNA translocation control. Taken together, my dissertation research demonstrated the potential of using recognition tunneling techniques to serve as a general readout system for single molecule DNA sequencing application.

  18. Topoisomerase I as a Biomarker: Detection of Activity at the Single Molecule Level

    PubMed Central

    Proszek, Joanna; Roy, Amit; Jakobsen, Ann-Katrine; Frøhlich, Rikke; Knudsen, Birgitta R.; Stougaard, Magnus

    2014-01-01

    Human topoisomerase I (hTopI) is an essential cellular enzyme. The enzyme is often upregulated in cancer cells, and it is a target for chemotherapeutic drugs of the camptothecin (CPT) family. Response to CPT-based treatment is dependent on hTopI activity, and reduction in activity, and mutations in hTopI have been reported to result in CPT resistance. Therefore, hTOPI gene copy number, mRNA level, protein amount, and enzyme activity have been studied to explain differences in cellular response to CPT. We show that Rolling Circle Enhanced Enzyme Activity Detection (REEAD), allowing measurement of hTopI cleavage-religation activity at the single molecule level, may be used to detect posttranslational enzymatic differences influencing CPT response. These differences cannot be detected by analysis of hTopI gene copy number, mRNA amount, or protein amount, and only become apparent upon measuring the activity of hTopI in the presence of CPT. Furthermore, we detected differences in the activity of the repair enzyme tyrosyl-DNA phosphodiesterase 1, which is involved in repair of hTopI-induced DNA damage. Since increased TDP1 activity can reduce cellular CPT sensitivity we suggest that a combined measurement of TDP1 activity and hTopI activity in presence of CPT will be the best determinant for CPT response. PMID:24434877

  19. Malachite green mediates homodimerization of antibody VL domains to form a fluorescent ternary complex with singular symmetric interfaces.

    PubMed

    Szent-Gyorgyi, Chris; Stanfield, Robyn L; Andreko, Susan; Dempsey, Alison; Ahmed, Mushtaq; Capek, Sarah; Waggoner, Alan S; Wilson, Ian A; Bruchez, Marcel P

    2013-11-15

    We report that a symmetric small-molecule ligand mediates the assembly of antibody light chain variable domains (VLs) into a correspondent symmetric ternary complex with novel interfaces. The L5* fluorogen activating protein is a VL domain that binds malachite green (MG) dye to activate intense fluorescence. Crystallography of liganded L5* reveals a 2:1 protein:ligand complex with inclusive C2 symmetry, where MG is almost entirely encapsulated between an antiparallel arrangement of the two VL domains. Unliganded L5* VL domains crystallize as a similar antiparallel VL/VL homodimer. The complementarity-determining regions are spatially oriented to form novel VL/VL and VL/ligand interfaces that tightly constrain a propeller conformer of MG. Binding equilibrium analysis suggests highly cooperative assembly to form a very stable VL/MG/VL complex, such that MG behaves as a strong chemical inducer of dimerization. Fusion of two VL domains into a single protein tightens MG binding over 1000-fold to low picomolar affinity without altering the large binding enthalpy, suggesting that bonding interactions with ligand and restriction of domain movements make independent contributions to binding. Fluorescence activation of a symmetrical fluorogen provides a selection mechanism for the isolation and directed evolution of ternary complexes where unnatural symmetric binding interfaces are favored over canonical antibody interfaces. As exemplified by L5*, these self-reporting complexes may be useful as modulators of protein association or as high-affinity protein tags and capture reagents. PMID:23978698

  20. Malachite green mediates homodimerization of antibody VL domains to form a fluorescent ternary complex with singular symmetric interfaces

    PubMed Central

    Szent-Gyorgyi, Chris; Stanfield, Robyn L.; Andreko, Susan; Dempsey, Alison; Ahmed, Mushtaq; Capek, Sara; Waggoner, Alan; Wilson, Ian A.; Bruchez, Marcel P.

    2013-01-01

    We report that a symmetric small molecule ligand mediates the assembly of antibody light chain variable domains (VLs) into a correspondent symmetric ternary complex with novel interfaces. The L5* Fluorogen Activating Protein (FAP) is a VL domain that binds malachite green dye (MG) to activate intense fluorescence. Crystallography of liganded L5* reveals a 2:1 protein:ligand complex with inclusive C2 symmetry, where MG is almost entirely encapsulated between an antiparallel arrangement of the two VL domains. Unliganded L5* VL domains crystallize as a similar antiparallel VL/VL homodimer. The complementarity determining regions (CDRs) are spatially oriented to form novel VL/VL and VL/ligand interfaces that tightly constrain a propeller conformer of MG. Binding equilibrium analysis suggests highly cooperative assembly to form a very stable VL/MG/VL complex, such that MG behaves as a strong chemical inducer of dimerization. Fusion of two VL domains into a single protein tightens MG binding over 1,000-fold to low picomolar affinity without altering the large binding enthalpy, suggesting that bonding interactions with ligand and restriction of domain movements make independent contributions to binding. Fluorescence activation of a symmetrical fluorogen provides a selection mechanism for the isolation and directed evolution of ternary complexes where unnatural symmetric binding interfaces are favored over canonical antibody interfaces. As exemplified by L5*, these self-reporting complexes may be useful as modulators of protein association or as high affinity protein tags and capture reagents. PMID:23978698

  1. Single Top Production at the Tevatron

    SciTech Connect

    Wu, Zhenbin; /Baylor U.

    2012-05-01

    We present recent results of single top quark production in the lepton plus jet final state, performed by the CDF and D0 collaborations based on 7.5 and 5.4 fb{sup -1} of p{bar p} collision data collected at {radical}s = 1.96 TeV from the Fermilab Tevatron collider. Multivariate techniques are used to separate the single top signal from the backgrounds. Both collaborations present measurements of the single top quark cross section and the CKM matrix element |V{sub tb}|. A search for anomalous Wtb coupling from D0 is also presented.

  2. Top quark mass measurement at the Tevatron

    SciTech Connect

    Guimaraes da Costa, Joao; /Harvard U.

    2004-12-01

    The authors report on the latest experimental measurements of the top quark mass by the CDF and D0 Collaborations at the Fermilab Tevatron. They present a new top mass measurement using the t{bar t} events collected by the D0 Collaboration in Run I between 1994 and 1996. This result is combined with previous measurements to yield a new world top mass average. They also describe several preliminary results using up to 193 pb{sup -1} of t{bar t} events produced in {bar p}p collisions at {radical}s = 1.96 TeV during the Run II of the Tevatron.

  3. Top Quark Properties from the Tevatron

    E-print Network

    M. Klute

    2006-05-15

    This report describes latest measurements and studies of top quark properties from the Tevatron in RunII with an integrated luminosity of up to 750pb-1. Due to its large mass of about 172GeV, the top quark provides a unique environment for tests of the Standard Model and is believed to yield sensitivity to new physics beyond the Standard Model. With data samples of close to 1fb-1 the CDF and D0 collaborations at the Tevatron enter a new aera of precision top quark measurements.

  4. Hadronization systematics and top mass reconstruction

    NASA Astrophysics Data System (ADS)

    Corcella, Gennaro

    2014-11-01

    I discuss a few issues related to the systematic error on the top mass mea- surement at hadron colliders, due to hadronization effects. Special care is taken about the impact of bottom-quark fragmentation in top decays, especially on the reconstruction relying on final states with leptons and J/? in the dilepton channel. I also debate the relation between the measured mass and its theoretical definition, and report on work in progress, based on the Monte Carlo simulation of fictitious top-flavoured hadrons, which may shed light on this issue and on the hadronization systematics.

  5. Top quark properties from the Tevatron

    SciTech Connect

    Klute, Markus; /MIT, LNS

    2006-05-01

    This report describes latest measurements and studies of top quark properties from the Tevatron in Run II with an integrated luminosity of up to 750 pb{sup -1}. Due to its large mass of about 172 GeV/c{sup 2}, the top quark provides a unique environment for tests of the Standard Model and is believed to yield sensitivity to new physics beyond the Standard Model. With data samples of close to 1 fb{sup -1} the CDF and D0 collaborations at the Tevatron enter a new area of precision top quark measurements.

  6. Precision Determination of the Top Quark Mass

    SciTech Connect

    Movilla Fernandez, Pedro A.; /LBL, Berkeley

    2007-05-01

    The CDF and D0 collaborations have updated their measurements of the mass of the top quark using proton-antiproton collisions at {radical}s = 1.96 TeV produced at the Tevatron. The uncertainties in each of the top-antitop decay channels have been reduced. The new Tevatron average for the mass of the top quark based on about 1 fb{sup -1} of data per experiment is 170.9 {+-} 1.8 GeV/c{sup 2}.

  7. Top-quark mass at hadron colliders

    E-print Network

    Andrea Castro

    2014-09-02

    Top quarks can be produced abundantly at hadron colliders like the Tevatron at Fermilab and the Large Hadron Collider at CERN, and a variety of measurements of top-quark properties have been gathered in the recent years from four experiments: CDF and D0 at the Tevatron and ATLAS and CMS at the Large Hadron Collider. In this review the most recent results on the measurement of the top-quark mass by the four different collaborations, with various techniques and considering different topologies, are reported.

  8. Top Quark Production at the Tevatron

    SciTech Connect

    Mietlicki, David J.

    2011-12-01

    The top quark is the most recently discovered of the standard model quarks, and because of its very large mass, studies of the top quark and its interactions are important both as tests of the standard model and searches for new phenomena. In this document, recent results of analyses of top quark production, via both the electroweak and strong interactions, from the CDF and D0 experiments are presented. The results included here utilize a dataset corresponding to up to 6 fb{sup -1} of integrated luminosity, slightly more than half of the dataset recorded by each experiment before the Tevatron was shutdown in September 2011.

  9. Secure Integration of Asymmetric and Symmetric Encryption Schemes

    E-print Network

    Pointcheval, David

    Secure Integration of Asymmetric and Symmetric Encryption Schemes Eiichiro FUJISAKI and Tatsuaki,okamotog@sucaba.isl.ntt.co.jp Abstract. This paper shows a generic and simple conversion from weak asymmetric and symmetric encryption, this conversion can be applied eÆciently to an asymmetric encryption scheme that provides a large enough coin

  10. The Collapse of an Axi-Symmetric, Swirling Vortex Sheet

    E-print Network

    Li, Xiaofan

    The Collapse of an Axi-Symmetric, Swirling Vortex Sheet Russel E. Ca isch #3; Xiaofan Li y of Mathematical Sciences, New York, NY 10012 August 25, 2003 Abstract An axi-symmetric and swirling vortex sheet of a single sheet but instability for other con#12;gurations of sheets. Due to the simplic- ity of vortex

  11. Progressive symmetric erythrokeratodermia with delayed intellectual milestones and convulsions

    PubMed Central

    Verma, Shyam B.; Wollina, Uwe

    2012-01-01

    Progressive symmetric erythrokeratoderma is an uncommon genodermatosis and is thought to arise due to mutations in the connexin gene, however, genetic heterogenicity has been described. Very few cases of neurological involvement have been described in this unusual entity. We report a case of progressive symmetric erythrokeratoderma, with convulsions and delayed intellectual milestones. PMID:23130266

  12. Progressive symmetric erythrokeratodermia with delayed intellectual milestones and convulsions.

    PubMed

    Verma, Shyam B; Wollina, Uwe

    2012-01-01

    Progressive symmetric erythrokeratoderma is an uncommon genodermatosis and is thought to arise due to mutations in the connexin gene, however, genetic heterogenicity has been described. Very few cases of neurological involvement have been described in this unusual entity. We report a case of progressive symmetric erythrokeratoderma, with convulsions and delayed intellectual milestones. PMID:23130266

  13. Symmetric Functions and P-Recursiveness Ira M. Gessel1

    E-print Network

    Gessel, Ira M.

    integer matrices with given row and column sums, have solutions which can be expressed as coefficients symmetric function. To evaluate this scalar product, we expand f and the hi in power sum symmetric functions, and use the orthogonality of the power sum sym- metric functions. We give examples of explicit formulas

  14. Reciprocal Symmetric Boltzmann Function and Unified Boson-Fermion Statistics

    E-print Network

    Mushfiq Ahmad; Muhammad O. G. Talukder

    2007-05-05

    The differential equation for Boltzmann's function is replaced by the corresponding discrete finite difference equation. The difference equation is, then, symmetrized so that the equation remains invariant when step d is replaced by -d. The solutions of this equation come in Boson-Fermion pairs. Reciprocal symmetric Boltzmann's function, thus, unifies both Bosonic and Fermionic distributions.

  15. SYMMETRIC AND ASYMMETRIC MULTIPLE CLUSTERS IN AN ELLIPTIC SYSTEM

    E-print Network

    Wei, Jun-cheng

    SYMMETRIC AND ASYMMETRIC MULTIPLE CLUSTERS IN AN ELLIPTIC SYSTEM JUNCHENG WEI AND MATTHIAS WINTER of ffl. A cluster is a combination of several spikes concentrating at the same point. In this paper, we rigorously show the existence of symmetric and asymmetric multiple clusters. This result is new for elliptic

  16. COMPLEX CROWNS OF RIEMANN SYMMETRIC SPACES AND MATSUKI DUALITY

    E-print Network

    COMPLEX CROWNS OF RIEMANN SYMMETRIC SPACES AND MATSUKI favorite subjects of last 10-* *15 years - complex crowns of Riemannian symmetric spaces. In the last year is that there is a canonical G-invariant Stein neighborhood of X - complex crown Crown (X)-which must universally appear

  17. COMPLEX CROWNS OF RIEMANN SYMMETRIC SPACES AND MATSUKI DUALITY

    E-print Network

    COMPLEX CROWNS OF RIEMANN SYMMETRIC SPACES AND MATSUKI DUALITY Simon Gindikin Soji Kaneyuki­15 years ­ complex crowns of Riemannian symmetric spaces. In the last year there was a substantial progress ­ complex crown Crown(X)­which must universally appear in geometric and analytic problems on X [G

  18. SOME REMARKS ON COMPLEX CROWNS OF RIEMANN SYMMETRIC SPACES

    E-print Network

    SOME REMARKS ON COMPLEX CROWNS OF RIEMANN SYMMETRIC not start from a formal definition of crowns of Riemann symmetric spaces. There is only a confidence that for each such space X there is a canonical Stein neighborhood Crown (X), on which it can be extended to all

  19. SOME REMARKS ON COMPLEX CROWNS OF RIEMANN SYMMETRIC SPACES

    E-print Network

    SOME REMARKS ON COMPLEX CROWNS OF RIEMANN SYMMETRIC SPACES Simon Gindikin Abstract. We discuss definition of crowns of Riemann symmetric spaces. There is only a confidence that for each such space X there is a canonical Stein neighborhood Crown(X), on which it can be extended to all natural geometrical constructions

  20. A symmetric surface micromachined gyroscope with decoupled oscillation modes

    E-print Network

    Akin, Tayfun

    A symmetric surface micromachined gyroscope with decoupled oscillation modes Said Emre Alper Abstract This paper reports a new symmetric gyroscope structure that allows both matched resonant beam design. The gyroscope structure is designed using a standard three-layer polysilicon surface

  1. Photonic Molecules and Spectral Engineering

    E-print Network

    Boriskina, Svetlana V.

    2010-01-01

    This chapter reviews the fundamental optical properties and applications of photonic molecules (PMs) – photonic structures formed by electromagnetic coupling of two or more optical microcavities (photonic atoms). Controllable ...

  2. Molecules Best Paper Award 2015.

    PubMed

    McPhee, Derek J

    2015-01-01

    Molecules instituted some years ago a "Best Paper" award to recognize the most outstanding papers in the area of organic synthesis, natural products, medicinal chemistry and molecular diversity published each year in Molecules. We are pleased to announce the third "Molecules Best Paper Award" for 2015. The winners were chosen by the Editor-in-Chief and selected editorial board members from among all the papers published in 2011. Reviews and research papers were evaluated separately. We are pleased to announce that the following eight papers have won the Molecules Best Paper Award for 2015:[...]. PMID:25611427

  3. Surfactants: Helping Molecules Get Along

    NSDL National Science Digital Library

    2014-09-18

    Students learn about the basics of molecules and how they interact with each other. They learn about the idea of polar and non-polar molecules and how they act with other fluids and surfaces. Students acquire a conceptual understanding of surfactant molecules and how they work on a molecular level. They also learn of the importance of surfactants, such as soaps, and their use in everyday life. Through associated activities, students explore how surfactant molecules are able to bring together two substances that typically do not mix, such as oil and water. This lesson and its associated activities are easily scalable for grades 3-12.

  4. Aromatic molecules as spintronic devices

    SciTech Connect

    Ojeda, J. H., E-mail: judith.ojeda@uptc.edu.co [Instituto de Alta investigación, Universidad de Tarapacá, Casilla 7D Arica (Chile); Grupo de Física de Materiales, Universidad Pedagógica y Tecnológica de Colombia, Tunja (Colombia); Orellana, P. A. [Departamento de Física, Universidad Técnica Federico Santa María, Casilla 110-V, Valparaíso (Chile)] [Departamento de Física, Universidad Técnica Federico Santa María, Casilla 110-V, Valparaíso (Chile); Laroze, D. [Instituto de Alta investigación, Universidad de Tarapacá, Casilla 7D Arica (Chile)] [Instituto de Alta investigación, Universidad de Tarapacá, Casilla 7D Arica (Chile)

    2014-03-14

    In this paper, we study the spin-dependent electron transport through aromatic molecular chains attached to two semi-infinite leads. We model this system taking into account different geometrical configurations which are all characterized by a tight binding Hamiltonian. Based on the Green's function approach with a Landauer formalism, we find spin-dependent transport in short aromatic molecules by applying external magnetic fields. Additionally, we find that the magnetoresistance of aromatic molecules can reach different values, which are dependent on the variations in the applied magnetic field, length of the molecules, and the interactions between the contacts and the aromatic molecule.

  5. How far the postorogenic extensional tectonics in the Aegean domain is symmetric?

    NASA Astrophysics Data System (ADS)

    Augier, Romain; Jolivet, Laurent; Gadenne, Leslie; Driussi, Olivier

    2013-04-01

    Current models to explain the finite geometry of the Aegean domain and the exhumation of the eclogite-bearing HP rocks in the Aegean domain rely on the recognition of a synorogenic exhumation regime followed by a postorogenic back-arc extension. A first generation of low-angle normal faults (LANF) developed during the subduction and the formation of the Hellenic Eocene orogenic wedge contemporaneously with the overthrusting of the Cycladic Blueschists over basement units. Other LANF were formed subsequently and accompanied the development of Metamorphic Core Complexes (MCC) during the collapse of the internal zones in the back-arc domain. Most of the stretching during postorogenic extension was accommodated by N-dipping LANF with N- to NE-sense of shear pertaining to the North Cycladic Detachment System (NCDS). More recently, the description of the top-to-the-south West Cycladic Detachment System (WCDS) resulted in a more symmetrical character of the postorogenic extension. However, the transition in time and space between these major structures, particularly the NCDS and the WCDS, which is a key question to understand the dynamics of the back-arc extension, remains widely unclear. The Folegandros-Sikinos area, whose tectonometamorphic evolution appears poorly constrained, is however quite exemplary of this discussion. Located to the south of the Cycladic Archipelago, at short distance from the WCDS last outcrop in Serifos Island, this area offers the opportunity to study both the synorogenic deformation preserved at the vicinity of the Cycladic basement and the structural transition between areas characterised by top-to-the-North and top-to-the-South kinematics during the postorogenic history. Based on an extensive field survey making the link between kinematics of the noncoaxial deformation and changing metamorphic conditions, we show that (1) a E-W syn-blueschists facies deformation is preserved within the HP lenses; (2) a penetrative, post-blueschists facies top-to-the-North sense of shear is present throughout the study area and (3) deformation that concentrates in the vicinity of the contact with the Cycladic basement is only characterized by a top-to-the-North kinematics. These results imply (4) the activity of a major postorogenic LANF roofing the Cycladic Blueschists (5) and the complete overprint of initial top-to-the-South thrust kinematics by top-to-the-North ones over the contact with the Cycladic basement that are consistent with a strong asymmetry of the deformation. Only a late, localized ductile-brittle deformation is recognized and thus ascribed to the activity of the WCDS to the West of the study area. LANF dipping in opposite directions with opposite sense of shear are then restricted to the west of Sifnos Island and separated from the central Cyclades by a sharp transition, highlighting a highly non-cylindrical deformation. Asymmetry of the postorogenic extension could be correlated with the amount of stretching. Rather symmetric deformation seems to occur in marginal areas of the domain while asymmetric deformation is encountered within highly-extended areas where lower crustal material is exhumed within MCCs.

  6. Bicriterion seriation methods for skew-symmetric matrices.

    PubMed

    Brusco, Michael J; Stahl, Stephanie

    2005-11-01

    The decomposition of an asymmetric proximity matrix into its symmetric and skew-symmetric components is a well-known principle in combinatorial data analysis. The seriation of the skew-symmetric component can emphasize information corresponding to the sign or absolute magnitude of the matrix elements, and the choice of objective criterion can have a profound impact on the ordering. In this research note, we propose a bicriterion approach for seriation of a skew-symmetric matrix incorporating both sign and magnitude information. Two numerical demonstrations reveal that the bicriterion procedure is an effective alternative to direct seriation of the skew-symmetric matrix, facilitating favourable trade-offs among sign and magnitude information. PMID:16293204

  7. Color symmetrical superconductivity in a schematic nuclear quark model

    E-print Network

    Henrik Bohr; João da Providência

    2009-10-13

    In this note, a novel BCS-type formalism is constructed in the framework of a schematic QCD inspired quark model, having in mind the description of color symmetrical superconducting states. The physical properties of the BCS vacuum (average numbers of quarks of different colors) remain unchanged under an arbitrary color rotation. In the usual approach to color superconductivity, the pairing correlations affect only the quasi-particle states of two colors, the single particle states of the third color remaining unaffected by the pairing correlations. In the theory of color symmetrical superconductivity here proposed, the pairing correlations affect symmetrically the quasi-particle states of the three colors and vanishing net color-charge is automatically insured. It is found that the groundstate energy of the color symmetrical sector of the Bonn model is well approximated by the average energy of the color symmetrical superconducting state proposed here.

  8. Single molecule tracking

    DOEpatents

    Shera, E. Brooks (Los Alamos, NM)

    1988-01-01

    A detection system is provided for identifying individual particles or molecules having characteristic emission in a flow train of the particles in a flow cell. A position sensitive sensor is located adjacent the flow cell in a position effective to detect the emissions from the particles within the flow cell and to assign spatial and temporal coordinates for the detected emissions. A computer is then enabled to predict spatial and temporal coordinates for the particle in the flow train as a function of a first detected emission. Comparison hardware or software then compares subsequent detected spatial and temporal coordinates with the predicted spatial and temporal coordinates to determine whether subsequently detected emissions originate from a particle in the train of particles. In one embodiment, the particles include fluorescent dyes which are excited to fluoresce a spectrum characteristic of the particular particle. Photones are emitted adjacent at least one microchannel plate sensor to enable spatial and temporal coordinates to be assigned. The effect of comparing detected coordinates with predicted coordinates is to define a moving sample volume which effectively precludes the effects of background emissions.

  9. Single molecule tracking

    DOEpatents

    Shera, E.B.

    1987-10-07

    A detection system is provided for identifying individual particles or molecules having characteristic emission in a flow train of the particles in a flow cell. A position sensitive sensor is located adjacent the flow cell in a position effective to detect the emissions from the particles within the flow cell and to assign spatial and temporal coordinates for the detected emissions. A computer is then enabled to predict spatial and temporal coordinates for the particle in the flow train as a function of a first detected emission. Comparison hardware or software then compares subsequent detected spatial and temporal coordinates with the predicted spatial and temporal coordinates to determine whether subsequently detected emissions originate from a particle in the train of particles. In one embodiment, the particles include fluorescent dyes which are excited to fluoresce a spectrum characteristic of the particular particle. Photons are emitted adjacent at least one microchannel plate sensor to enable spatial and temporal coordinates to be assigned. The effect of comparing detected coordinates with predicted coordinates is to define a moving sample volume which effectively precludes the effects of background emissions. 3 figs.

  10. Top 5 Majors Among Respondents 1. Accounting

    E-print Network

    Hemmers, Oliver

    Top 5 Majors Among Respondents 1. Accounting 2. Finance 3. Management 4. Marketing 5. Economics 0 on the Career Services' main web page (http://hire.unlv.edu). We use the commercial software program "Survey

  11. Theme: Women Reach for the Top.

    ERIC Educational Resources Information Center

    Ducci, Maria Angelica; And Others

    1993-01-01

    Includes "Women in Authority: The Ideal and the Reality" (Ducci); "Unequal Race to the Top"; "What Training for Career Advancement?" (Fromont); "Motherhood, Family, Career" (Seguret); and "It's Up to Women to Make Things Change." (JOW)

  12. Top 5 Hidden Hazards in the Home

    MedlinePLUS

    ... Resource Center CO Poster Contest Toy Recall Statistics Home / Safety Education / Neighborhood Safety Network / Posters En Español Top 5 Hidden Home Hazards Magnets, recalled products, windows, tipover and pools ...

  13. Evaluating Top-k Selection Queries

    Microsoft Academic Search

    Surajit Chaudhuri; Luis Gravano

    1999-01-01

    In many applications, users specify target val- ues for certain attributes, without requiring exact matches to these values in return. In- stead, the result to such queries is typically a rank of the \\\\top k\\

  14. Enter Keyword(s) Today's Ecology Top

    E-print Network

    Enter Keyword(s) Today's Ecology Top News OMG's Business Ecology Initiative BEI Reaches 250 Member Advertisement Ecology Topics Botany Climate Research Ecology Environment Environmental Microbiology Environmental Monitoring Environmental Research Fisheries Research Marine Biology Meteorology Molecular Ecology

  15. Review of recent top quark measurements

    SciTech Connect

    Heinson, A.P.; /UC, Riverside

    2004-11-01

    At the Tevatron Collider at Fermilab, a large number of top quarks have been produced in the ongoing run. The CDF and D0 collaborations have made first measurements of the t{bar t} cross section in several decay channels, and have measured the top quark mass. In addition, they have set new limits on the cross sections for single top quark production, and have started to measure some of the properties of the top quark via studies of its decays. This paper summarizes the status of these measurements and discusses where they are heading in the next few years. The paper is based on a talk I gave at the Rencontres du Vietnam in Hanoi, August 2004; the results have been updated to show the latest values and new measurements.

  16. VIEW OF PDP TANK TOP, LEVEL 0?, WITH VERTICAL ELEMENTS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF PDP TANK TOP, LEVEL 0?, WITH VERTICAL ELEMENTS IN BACKGROUND, LTR TANK TOP ON LEFT, AND SHEAVE RACK ELEMENTS AT TOP, LOOKING NORTH - Physics Assembly Laboratory, Area A/M, Savannah River Site, Aiken, Aiken County, SC

  17. VIEW OF PDP TANK TOP, LEVEL 0?, WITH LTR TANK ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF PDP TANK TOP, LEVEL 0?, WITH LTR TANK TOP ON LEFT, LOOKING NORTHEAST. CRANE AND VERTICAL HOISTING ELEMENTS AT TOP - Physics Assembly Laboratory, Area A/M, Savannah River Site, Aiken, Aiken County, SC

  18. Multidimensional top-k dominating queries

    Microsoft Academic Search

    Man Lung Yiu; Nikos Mamoulis

    2009-01-01

    Abstract The top-k dominating,query returns k data ob- jects which,dominate,the highest number,of objects in a dataset. This query is an important tool for decision support since it provides data analysts an intuitive way for finding significant objects. In addition, it combines the advantages of top-k and skyline queries without sharing their disadvan- tages: (i) the output size can be controlled,

  19. The discovery of the top quark

    SciTech Connect

    Sinervo, P.K. [Univ. of Toronto, Ontario, CA (Canada). Dept. of Physics; The CDF Collaboration

    1995-12-01

    The top quark and the Higgs boson are the heaviest elementary particles predicted by the standard model. The four lightest quark flavours, the up, down, strange and charm quarks, were well-established by the mid-1970`s. The discovery in 1977 of the {Tau} resonances, a new family of massive hadrons, required the introduction of the fifth quark flavour. Experimental and theoretical studies have indicated that this quark also has a heavier partner, the top quark.

  20. Single Top Physics at Hadron Colliders

    E-print Network

    Giorgio Chiarelli

    2013-02-07

    The production of top quark in electroweak processes was first observed in 2010 at the Tevatron. Since then it has been carefully studied at both LHC and Tevatron. Single top production proceeds through different channels and allows a direct determination of Cabibbo-Kobayashi-Maskawa matrix element $|V_{tb}|$. We will present the current status of searches and observation and discuss the results obtained so far and perspectives at hadron machines.