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1

Entanglement of polar symmetric top molecules as candidate qubits.  

PubMed

Proposals for quantum computing using rotational states of polar molecules as qubits have previously considered only diatomic molecules. For these the Stark effect is second-order, so a sizable external electric field is required to produce the requisite dipole moments in the laboratory frame. Here we consider use of polar symmetric top molecules. These offer advantages resulting from a first-order Stark effect, which renders the effective dipole moments nearly independent of the field strength. That permits use of much lower external field strengths for addressing sites. Moreover, for a particular choice of qubits, the electric dipole interactions become isomorphous with NMR systems for which many techniques enhancing logic gate operations have been developed. Also inviting is the wider chemical scope, since many symmetric top organic molecules provide options for auxiliary storage qubits in spin and hyperfine structure or in internal rotation states. PMID:22029292

Wei, Qi; Kais, Sabre; Friedrich, Bretislav; Herschbach, Dudley

2011-10-21

2

Rovibrational interaction and vibrational constants of the symmetric top molecule 14NF3.  

PubMed

Several accurate experimental values of the ?(C) and ?(B) rotation-vibration interaction parameters and ?(i), x(ij), and g(ij) 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 (14)NF3. 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

Najib, Hamid

2013-05-23

3

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

PubMed Central

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.

2013-01-01

4

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

NASA Astrophysics Data System (ADS)

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 ?g1s??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.

Buth, Christian; Santra, Robin

2008-01-01

5

Quantum effects in the capture of charged particles by dipolar polarizable symmetric top molecules. I. General axially nonadiabatic channel treatment.  

PubMed

The rate coefficients for capture of charged particles by dipolar polarizable symmetric top molecules in the quantum collision regime are calculated within an axially nonadiabatic channel approach. It uses the adiabatic approximation with respect to rotational transitions of the target within first-order charge-dipole interaction and takes into account the gyroscopic effect that decouples the intrinsic angular momentum from the collision axis. The results are valid for a wide range of collision energies (from single-wave capture to the classical limit) and dipole moments (from the Vogt-Wannier and fly-wheel to the adiabatic channel limit). PMID:24007001

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

2013-08-28

6

The methyl cyanide hot and warm cores in Orion - Statistical equilibrium excitation models of a symmetric-top molecule  

NASA Astrophysics Data System (ADS)

High-velocity resolution line profiles have been obtained for 50 lines of the top-symmetric-top molecule CH3CN, from J = 6-5 up to J = 16-15 with components from K = O to K = 7 in the vicinity of OMC-1. The profiles reveal two distinct regions of both broad and narrow emission at 5.1 km/s, and 8.7 km/s, respectively. The kinetic temperatures for these regions are 275 (+ or -25) K and 95 (+ or -8) K respectively. It is found that CH3CN abundance is enhanced in the hot core by a factor of 10 relative to the quiescent cloud. The excitation of statistical equilibrium (SE) models fitted to the resolved line profiles is compared to that predicted by the rotational equilibrium (RTE) analytic method. It is found that the RTE method can accurately predict kinetic temperature for both of the nearly thermalized regions of OMC-1 when rotational temperature is not determined from levels which span a large range of J, but not by Hollis's (1982) method based on adjacent J levels. For high temperature regions the RTE method did not correctly predict kinetic temperature in the range of densities from 10 to the 2.5 per cu cm to 10 to the 6th per cu cm which are common in molecular clouds.

Loren, R. B.; Mundy, L. G.

1984-11-01

7

About Hot Bands and PAPE Bands in Spectra of C3v Symmetric Top Molecules  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to present simple ideas about two kinds of infrared bands which are not considered in classical text books, namely hot bands and PAPE bands. The presentation is limited to molecules with C3v symmetry. PAPE bands are parallel bands with a perpendicular structure and belong to the A1 + A2 vibrational symmetry. Their different appearances are discussed. Hot bands are very simple when the lower state has an A1 vibrational symmetry. We concentrate on the case where it has an E-type symmetry. Many examples of actual bands are quoted.

Graner, G.

1993-09-01

8

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

NASA Astrophysics Data System (ADS)

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/cm2 each with 160 fs duration) with time delays were probed in a quantum-state resolved manner by employing resonant enhanced multiphoton ionization via the S1 <-- S0 601 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.

Baek, Daeyul; Hasegawa, Hirokazu; Ohshima, Yasuhiro

2011-06-01

9

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

PubMed

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

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

2013-10-14

10

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

11

Molecular structure determination from x-ray scattering patterns of laser-aligned symmetric-top molecules  

Microsoft Academic Search

We investigate the molecular structure information contained in the x-ray diffraction patterns of an ensemble of rigid CF3Br molecules aligned by an intense laser pulse at finite rotational temperature. The diffraction patterns are calculated at an x-ray photon energy of 20 keV to probe molecular structure at angstrom-scale resolution. We find that a structural reconstruction algorithm based on iterative phase

P. J. Ho; D. Starodub; D. K. Saldin; V. L. Shneerson; A. Ourmazd; R. Santra

2009-01-01

12

Molecular structure determination from x-ray scattering patterns of laser-aligned symmetric-top molecules  

SciTech Connect

We investigate the molecular structure information contained in the x-ray diffraction patterns of an ensemble of rigid CF{sub 3}Br molecules aligned by an intense laser pulse at finite rotational temperature. The diffraction patterns are calculated at an x-ray photon energy of 20 keV to probe molecular structure at angstrom-scale resolution. We find that a structural reconstruction algorithm based on iterative phase retrieval fails to extract a reliable structure. However, the high atomic number of Br compared with C or F allows each diffraction pattern to be treated as a hologram. Using this approach, the azimuthal projection of the molecular electron density about the alignment axis may be retrieved.

Ho, P. J. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Starodub, D. [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States); Saldin, D. K.; Shneerson, V. L.; Ourmazd, A. [Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201 (United States); Santra, R. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Physics, University of Chicago, Chicago, Illinois 60637 (United States)

2009-10-07

13

Molecular structure determination from x-ray scattering patterns of laser-aligned symmetric-top molecules.  

SciTech Connect

We investigate the molecular structure information contained in the x-ray diffraction patterns of an ensemble of rigid CF{sub 3}Br molecules aligned by an intense laser pulse at finite rotational temperature. The diffraction patterns are calculated at an x-ray photon energy of 20 keV to probe molecular structure at angstrom-scale resolution. We find that a structural reconstruction algorithm based on iterative phase retrieval fails to extract a reliable structure. However, the high atomic number of Br compared with C or F allows each diffraction pattern to be treated as a hologram. Using this approach, the azimuthal projection of the molecular electron density about the alignment axis may be retrieved.

Ho, P. J.; Starodub, D.; Saldin, D. K.; Shneerson, V. L.; Ourmazd, A.; Santra, R.; Arizona State Univ.; Univ. of Wisconsin at Milwaukee; Univ. of Chicago

2009-10-07

14

Molecular structure determination from x-ray scattering patterns of laser-aligned symmetric-top molecules  

NASA Astrophysics Data System (ADS)

We investigate the molecular structure information contained in the x-ray diffraction patterns of an ensemble of rigid CF3Br molecules aligned by an intense laser pulse at finite rotational temperature. The diffraction patterns are calculated at an x-ray photon energy of 20 keV to probe molecular structure at angstrom-scale resolution. We find that a structural reconstruction algorithm based on iterative phase retrieval fails to extract a reliable structure. However, the high atomic number of Br compared with C or F allows each diffraction pattern to be treated as a hologram. Using this approach, the azimuthal projection of the molecular electron density about the alignment axis may be retrieved.

Ho, P. J.; Starodub, D.; Saldin, D. K.; Shneerson, V. L.; Ourmazd, A.; Santra, R.

2009-10-01

15

Molecular structure determination from x-ray scattering patterns of laser-aligned symmetric-top molecules.  

PubMed

We investigate the molecular structure information contained in the x-ray diffraction patterns of an ensemble of rigid CF(3)Br molecules aligned by an intense laser pulse at finite rotational temperature. The diffraction patterns are calculated at an x-ray photon energy of 20 keV to probe molecular structure at angstrom-scale resolution. We find that a structural reconstruction algorithm based on iterative phase retrieval fails to extract a reliable structure. However, the high atomic number of Br compared with C or F allows each diffraction pattern to be treated as a hologram. Using this approach, the azimuthal projection of the molecular electron density about the alignment axis may be retrieved. PMID:19814536

Ho, P J; Starodub, D; Saldin, D K; Shneerson, V L; Ourmazd, A; Santra, R

2009-10-01

16

Horseshoes for the nearly symmetric heavy top  

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

17

Rotational excitations of a symmetric top in cubic orientational potentials: CH3D matrix-isolated in argon and krypton  

Microsoft Academic Search

Measurements with inelastic neutron scattering of the rotational spectra of the symmetric top molecule CH3D as substitutional impurities in crystalline argon and krypton are presented. The energy of the J=1 doublet is shifted by 33% and 27% respectively, compared to the completely free rotor. Spin-rotational wave functions for the free CH3D rotor are constructed and used for the calculation of

B. Asmussen; D. Balszunat; M. Prager; C. J. Carlile; H. Büttner

1995-01-01

18

Rectification in Symmetric Conjugated Molecules with Asymmetric Linkers  

NASA Astrophysics Data System (ADS)

Demonstrating single-molecule rectification is an important step towards the realization of molecule-based electronic devices. Most molecules put forward as potential rectifiers employ asymmetric molecular backbones. In contrast, we show that we can create rectifying junctions by designing asymmetry only into the linker groups used to bond the molecule to metal electrodes. Our molecules consist of a conjugated backbone terminated with methylsulfide on one end and methyl-trimethyltin on the other. These molecules couple to Au electrodes through an Au-SMe donor acceptor bond, which serves as the electronically weak link, and a Au-C covalent bond, which is created in-situ after the SnMe3 cleaves off [1]. We create thousands of molecular junctions using a modified STM setup in a solution of molecules, measure their current-voltage (IV) characteristics and create averaged IV curves. We find that asymmetrically terminated molecules show non-linear IV curves with significant rectification, while molecules terminated symmetrically with either SMe or SnMe3 do not show substantial rectification. We also find that the rectification direction is dependent on molecular orientation in the junction. [1] Chen, W., et al., J. Am. Chem. Soc., 2011. 133(43): p. 17160-17163

Batra, Arunabh; Meisner, Jeffrey S.; Widawsky, Jonathan R.; Huisman, Eek; Nuckolls, Colin; Venkataraman, Latha

2012-02-01

19

Systematic studies of molecular vibrational anharmonicity and vibration-rotation interaction by self-consistent-field higher derivative methods: Applications to asymmetric and symmetric top and linear polyatomic molecules  

SciTech Connect

Inclusion of the anharmonicity normal mode vibrations (i.e., the third and fourth (and higher) derivatives of a molecular Born-Oppenheimer potential energy surface) is necessary in order to theoretically reproduce experimental fundamental vibrational frequencies of a molecule. Although ab initio determinations of harmonic vibrational frequencies may give errors of only a few percent by the inclusion of electron correlation within a large basis set for small molecules, in general, molecular fundamental vibrational frequencies are more often available from high resolution vibration-rotation spectra. Recently developed analytic third derivatives methods for self-consistent-field (SCF) wavefunctions have made it possible to examine with previously unavailable accuracy and computational efficiency the anharmonic force fields of small molecules.

Clabo, D.A. Jr.

1987-04-01

20

Angular Relaxation of the Symmetrical Top. II. The Rough Sphere  

Microsoft Academic Search

We investigate the reorientation of molecules in a bath of atoms without internal degrees of freedom. A Markoffian kinetic equation for the rough sphere model is formulated. A collision operator is derived and the appropriate kinetic equation for the two time orientational autocorrelation functions is solved for a variety of molecular parameters. It is found that the finite collision rough

K. L. Rider; M. Fixman

1972-01-01

21

Phase behavior of symmetric disk-coil molecules  

NASA Astrophysics Data System (ADS)

We investigate the self-assembly of symmetric disk-coil molecules using Monte Carlo simulations in the NPT ensemble. Our molecules are composed of a planar disk (head) that is covalently bonded to a single coil (tail), and can be regarded as disk-coil copolymers. For this system, we observe a variety of phases depending on the temperature and the effective interactions between the disk and coil regions. In particular, we find a disordered, a lamellar, a perforated lamellar, and a crystal phase. Furthermore, the orientational correlation (or ordering) of the disks within the crystal phase is found to be stronger compared to the pure disk case, which we also explicitly simulate. The enhanced order is due to the confinement imposed by the mesophase formation. Our results are relevant for organic photoactive (typically planar) molecules that are functionalized with alkyl tails to improve their processing properties as well as their long-range order in the solid phase, and can also help to rationalize some biologically observed phases of chlorophyll seen in the photosynthetic apparatus of green bacteria.

Kim, Yongjoo; Alexander-Katz, Alfredo

2010-05-01

22

Using Fixed-Node Diffusion Monte Carlo to Probe Rotation-Vibration Coupling in Highly Fluxional Asymmetric Top Molecules  

NASA Astrophysics Data System (ADS)

Our group has developed a fixed-node Diffusion Monte Carlo (DMC) methodology that can be used to describe rotationally excited states of highly fluxional symmetric top molecules. This technique has been thoroughly benchmarked using rotationally excited states of H_3^+, H_3O^+, and NH_3 with J?12. Here, we report a recently developed extension of this methodology to asymmetric top molecules which undergo large amplitude, zero-point vibrational motion. The nodal surfaces used in the fixed-node DMC calculations are obtained from rigid-rotor wave functions calculated using the system's ground state vibrationally averaged rotational constants. The algorithms used to evaluate node crossing and re-crossing are generalized to account for the pronounced curvature exhibited by the nodal surfaces of asymmetric top molecules with ? ? 0 due to the strong mixing of two or more symmetric top basis functions. Finally, the insight that can be obtained from these calculations into the nature and strength of the vibration-rotation coupling present in highly fluxional asymmetric top molecules will be briefly discussed and further elaborated on in the following talk. A. S. Petit and A. B. McCoy, J. Phys. Chem. A 113, 12706 (2009). A. S. Petit, B. A. Wellen, and A. B. McCoy, J. Chem. Phys. 136, 074101 (2012).

Petit, Andrew S.; Wellen, Bethany A.; McCoy, Anne B.

2012-06-01

23

Path integral method applied to the brownian rotation of a symmetric top  

NASA Astrophysics Data System (ADS)

The conditional probability density function in angular velocities space is obtained in an exact and closed expression for a symmetric top undergoing brownian motion. The distribution turns out to be non-gaussian. We obtain the distribution function by shifting the problem of solving stochastic differential equations to the problem of solving ordinary differential equations. This is done using the method of path integrals developed by Feynman and Hibbs for quantum mechanics. Mailing address: Apdo. Postal 55-534, México, D.F., C.P. 09340, México.

Braun, E.; Cortes, Emilio

1986-05-01

24

Spectral moments of the rotational correlation functions for the first- and second-rank tensors of asymmetric top molecules  

NASA Astrophysics Data System (ADS)

A method of evaluating the spectral moments M12k of the rotational correlation functions for the first- and second-rank tensors of rigid asymmetric top molecules is developed. It is based on the calculation of the coefficients of a Taylor series expansion of the vector and tensor orientational correlation functions about t = 0 with the help of angular momentum theory, and is applicable to a pair intermolecular interaction potential with arbitrary dependence on the angular variables. Equations for the second (Ml2), fourth (Ml4), and sixth (Ml6) spectral moments are obtained as a demonstration of the ability of the method. The results for Ml2 and Ml4 coincide with previously known values and the equation for Ml6 is new. As particular cases, the theory contains the results for classical ensembles of symmetric tops, spherical tops, and linear molecules.

Kalmykov, Y. P.; Titov, S. V.

25

Rotational dynamics of rigid, symmetric top macromolecules. Application to circular cylinders  

NASA Astrophysics Data System (ADS)

The formalism for the calculation of translational friction coefficients of symmetric top macromolecules presented in a previous paper [M. M. Tirado and J. García de la Torre, J. Chem. Phys. 71, 2585 (1979)] is here extended to the evaluation of rotational friction and diffusion coefficients. We show how the introduction of symmetry considerations leads to a great reduction of the computational requirements needed to solve the hydrodynamic interaction equations. We also obtain the translation-rotation coupling tensor from which the center of hydrodynamic stress can be obtained. For a rigid ring we have derived analytical solutions that reduce to those obtained by other authors when the unmodified interaction tensor is used. The general formalism is finally applied to the calculation of the rotational diffusion coefficients of circular cylinders modeled as stacks of rings and extrapolated to zero bead size. The resulting values are critically compared with those from earlier studies.

Tirado, María M.; de La Torre, José García

1980-08-01

26

The relative reactivity of CH3D molecules with excited symmetric and antisymmetric stretching vibrations  

Microsoft Academic Search

Experimental and theoretical studies explore the reactivity of the symmetric and the antisymmetric stretching vibrations of monodeuterated methane (CH3D). Direct infrared absorption near 3000 cm?1 prepares CH3D molecules in three different vibrationally excited eigenstates that contain different amounts of symmetric C–H stretch (?1), antisymmetric C–H stretch (?4), and bending overtone (2?5) excitation. The reaction of vibrationally excited CH3D with photolytic

Sangwoon Yoon; Robert J. Holiday; Edwin L. Sibert; F. Fleming Crim

2003-01-01

27

The relative reactivity of CH3D molecules with excited symmetric and antisymmetric stretching vibrations  

Microsoft Academic Search

Experimental and theoretical studies explore the reactivity of the symmetric and the antisymmetric stretching vibrations of monodeuterated methane (CH3D). Direct infrared absorption near 3000 cm-1 prepares CH3D molecules in three different vibrationally excited eigenstates that contain different amounts of symmetric C-H stretch (nu1), antisymmetric C-H stretch (nu4), and bending overtone (2nu5) excitation. The reaction of vibrationally excited CH3D with photolytic

Sangwoon Yoon; Robert J. Holiday; Edwin L. Sibert; F. Fleming Crim

2003-01-01

28

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

SciTech Connect

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.

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

29

The relative reactivity of CH3D molecules with excited symmetric and antisymmetric stretching vibrations  

NASA Astrophysics Data System (ADS)

Experimental and theoretical studies explore the reactivity of the symmetric and the antisymmetric stretching vibrations of monodeuterated methane (CH3D). Direct infrared absorption near 3000 cm-1 prepares CH3D molecules in three different vibrationally excited eigenstates that contain different amounts of symmetric C-H stretch (?1), antisymmetric C-H stretch (?4), and bending overtone (2?5) excitation. The reaction of vibrationally excited CH3D with photolytic chlorine atoms (Cl, 2P3/2) yields CH2D products mostly in their vibrational ground state. Comparison of the vibrational action spectra with the simulated absorption spectra and further analysis using the calculated composition of the eigenstates show that the symmetric C-H stretching vibration (?1) promotes the reaction seven times more efficiently than the antisymmetric C-H stretching vibration (?4). Ab initio calculations of the vibrational energies and eigenvectors along the reaction coordinate demonstrate that this difference arises from changes in the initially excited stretching vibrations as the reactive Cl atom approaches. The ?1 vibration of CH3D becomes localized vibrational excitation of the C-H bond pointing toward the Cl atom, promoting the abstraction reaction, but the energy initially in the ?4 vibration flows into the C-H bonds pointing away from the approaching Cl atom and remains unperturbed during the reaction. A simple model using vibrational symmetries and vibrational adiabaticity predicts a general propensity for the greater efficiency of the symmetric stretch for accelerating the reaction in the vibrationally adiabatic limit.

Yoon, Sangwoon; Holiday, Robert J.; Sibert, Edwin L.; Crim, F. Fleming

2003-11-01

30

Level anti-crossings in ParaHydrogen Induced Polarization experiments with Cs-symmetric molecules  

NASA Astrophysics Data System (ADS)

Hyperpolarization by means of ParaHydrogen Induced Polarization (PHIP) has found increasing applications since its discovery. However, in the last decade only a few experiments have been reported describing the hydrogenation of symmetric molecules. A general AA?BB? system is studied here. Calculations of the spin dynamics with the density matrix formalism support the experimental findings, providing profound understanding of the experiments in Cs-symmetric molecules. Level anti-crossings between states related to the triplet and the singlet state of one pair of the protons are identified as being responsible for hyperpolarization transfer in a PHIP experiment, when the former p-H2 protons occupy the sites AA?.The hydrogenation of acetylene dicarboxylic acid dimethylester with parahydrogen is used to illustrate the case. The theoretical treatment applied to this particular reaction explains the signal enhancements in both groups of protons in the spectrum when the sample is placed in the proper magnetic field strength, including the phase inversion of the signal of the methyl group.The treatment described here can be extended to every molecule which can be approximated as an AA?BB? system.

Buljubasich, L.; Franzoni, M. B.; Spiess, H. W.; Münnemann, K.

2012-06-01

31

Rotational dynamics of an asymmetric-top molecule in parallel electric and nonresonant laser fields  

NASA Astrophysics Data System (ADS)

We present a theoretical study of the rotational dynamics of asymmetric-top molecules in an electric field and a parallel nonresonant linearly polarized laser pulse. The time-dependent Schrödinger equation is solved within the rigid rotor approximation. Using the benzonitrile molecule as a prototype, we investigate the field-dressed dynamics for experimentally accessible field configurations and compare these results to the adiabatic predictions. We show that for an asymmetric-top molecule in parallel fields, the formation of the pendular doublets and the avoided crossings between neighboring levels are the two main sources of nonadiabatic effects. We also provide the field parameters under which the adiabatic dynamics would be achieved.

Omiste, Juan J.; González-Férez, Rosario

2013-09-01

32

The role played by self-orientational properties in nematics of colloids with molecules axially symmetric.  

PubMed

The self-orientational structure factor as well as the short-time self-orientational diffusion coefficient is computed for colloids composed by nonspherical molecules. To compute the short-time dynamics the hydrodynamic interactions are not taken into account. The hard molecules with at least one symmetry axis considered are: rods, spherocylinders, and tetragonal parallelepipeds. Because both orientational properties in study are written in terms of the second and fourth order parameters, these automatically hold the features of the order parameters. That is, they present a discontinuity for first order transitions, determining in this way the spinodal line. In order to analyze the nematic phase only, we choose the appropriate values for the representative quantities that characterize the molecules. Different formalisms are used to compute the structural properties: de Gennes-Landau approach, Smoluchowski equation and computer simulations. Some of the necessary inputs are taken from literature. Our results show that the self-orientational properties play an important role in the characterization and the localization of axially symmetric phases. While the self-structure decreases throughout the nematics, the short-time self-diffusion does not decrease but rather increases. We study the evolution of the second and fourth order parameters; we find different responses for axial and biaxial nematics, predicting the possibility of a biaxial nematics in tetragonal parallelepiped molecules. By considering the second order in the axial-biaxial phase transition, with the support of the self-orientational structure factor, we are able to propose the density at which this occurs. The short-time dynamics is able to predict a different value in the axial and the biaxial phases. Because the different behavior of the fourth order parameter, the diffusion coefficient is lower for a biaxial phase than for an axial one. Therefore the self-structure factor is able to localize continuous phase transitions involving axially symmetric phases and the short-time self-orientational diffusion is able to distinguish the ordered phase by considering the degree of alignment, that is, axial or biaxial. PMID:20406010

Alarcón-Waess, O

2010-04-14

33

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

NASA Astrophysics Data System (ADS)

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.

Chandra, Suresh

34

Response functions for dimers and square-symmetric molecules in four-wave-mixing experiments with polarized light.  

PubMed

Four-wave-mixing nonlinear-response functions are given for intermolecular and intramolecular vibrations of a perpendicular dimer and intramolecular vibrations of a square-symmetric molecule containing a doubly degenerate state. A two-dimensional particle-in-a-box model is used to approximate the electronic wave functions and obtain harmonic potentials for nuclear motion. Vibronic interactions due to symmetry-lowering distortions along Jahn-Teller active normal modes are discussed. Electronic dephasing due to nuclear motion along both symmetric and asymmetric normal modes is included in these response functions, but population transfer between states is not. As an illustration, these response functions are used to predict the pump-probe polarization anisotropy in the limit of impulsive excitation. PMID:16095341

Smith, Eric Ryan; Farrow, Darcie A; Jonas, David M

2005-07-22

35

Extension of the Measurement, Assignment, and Fit in the Ground State of the Two-Top Molecule Methyl Acetate  

NASA Astrophysics Data System (ADS)

New spectroscopic data were recorded for the two-top molecule methyl acetate with a chirped-pulse Fourier transform microwave spectrometer at room temperature and a jet cooled sub-millimeterwave spectrometer. More than 650 new lines with J up to 35 and K up to 15 were assigned. In total, approximately 1500 lines were fitted with 34 parameters using the program BELGI-C_s-2tops to a standard deviation close to the measurement error. More precise determinations of the top-top interaction and the J, K dependent parameters as well as the influence of the total rotation on the top-top interaction were carried out. The extension of the ground state spectrum of methyl acetate is a necessary step before searching for the first torsional excited transition in both torsional modes in the room temperature spectrum.

Nguyen, H. V. L.; Kleiner, I.; Shipman, S.; Kobayashi, K.

2013-06-01

36

Non-Symmetric Push-Pull Molecules in the Gas Phase: High Resolution Stark Spectroscopy of M-Aminobenzoic Acid.  

NASA Astrophysics Data System (ADS)

The permanent electric dipole moments of two conformers of m-aminobenzoic acid (MABA) in their ground and electronically excited states have been experimentally determined by Stark-effect measurements in a molecular beam. The two conformers, differing by a rotation about the bond connecting the carboxylic acid group and aniline ring, have very similar rotational constants. However, the two conformers may be unambiguously assigned using their respective permanent dipole moment orientations. The possibility of excited state mixing in this non-symmetric biologically relevant push-pull molecule will be discussed.

Fleisher, Adam J.; Morgan, Philip J.; Pratt, David W.

2010-06-01

37

Flavor changing neutral current in rare top quark decay t ? cbar ll in generic Z' and left-right symmetric models  

NASA Astrophysics Data System (ADS)

We study the rare top decay t ? cbar ll, which involves flavor violation, as a possible probe of new physics. This decay is analyzed with the simplest Standard Model (SM) extensions with additional gauge symmetry U(l) or SU(2), known as generic Z' model or left-right symmetric model, respectively. The considered models allow to obtain this decay at tree level through Flavor Changing Neutral Currents (FCNC). We have considered diagonal non-universal couplings for up-type quark sector and found that BR(t ? cbar ll) for 1 TeV < Mz' < 3 TeV can be of order ~ 10-11 in generic Z' model or ~ 10-12 in left-right symmetric model.

Gaitán-Lozano, R.; Montes de Oca Y, J. H.; Díaz-Cruz, L.

2012-08-01

38

Crankshafts: using simple, flat C2h-symmetric molecules to direct the assembly of chiral 2D nanopatterns.  

PubMed

Linear D2h-symmetric bisisophthalic acids 1 and 2 and related substances have well-defined flattened structures, high affinities for graphite, and strong abilities to engage in specific intermolecular interactions. Their adsorption produces characteristic nanopatterns that reveal how 2D molecular organization can be controlled by reliable interadsorbate interactions such as hydrogen bonds when properly oriented by molecular geometry. In addition, the behavior of these compounds shows how large-scale organization can be obstructed by programming molecules to associate strongly according to competing motifs that have similar stability and can coexist smoothly without creating significant defects. Analogous new bisisophthalic acids 3a and 4a have similar associative properties, and their unique C2h-symmetric crankshaft geometry gives them the added ability to probe the poorly understood effect of chirality on molecular organization. Their adsorption shows how nanopatterns composed predictably of a single enantiomer can be obtained by depositing molecules that can respect established rules of association only by accepting neighbors of the same configuration. In addition, an analysis of the adsorption of crankshaft compounds 3a and 4a and their derivatives by STM reveals directly on the molecular level how kinetics and thermodynamics compete to control the crystallization of chiral compounds. In such ways, detailed studies of the adsorption of properly designed compounds on surfaces are proving to be a powerful way to discover and test rules that broadly govern molecular organization in both 2D and 3D. PMID:23092394

Zhou, Hui; Wuest, James D

2012-11-02

39

Studies on the Biosynthesis of Cholesterol. XVII. The Asymmetric Synthesis of a Symmetrical Molecule  

Microsoft Academic Search

The differentiation between two identical chemical groups in the Ca'a' 'bd molecule in enzymic reactions is discussed first. It is then shown that squalene biosynthesized from two molecules of [1-D2]farnesyl pyrophosphate is asymmetrically labelled at one of its central methylene carbon atoms, one of the deuterium atoms at C-1 of one of the two farnesyl residues having been replaced stereospecifically

J. W. Cornforth; Rita H. Cornforth; C. Donninger; G. Popjak; G. Ryback; G. J. Schroepfer

1966-01-01

40

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

NASA Astrophysics Data System (ADS)

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, Ih-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.

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

41

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

SciTech Connect

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.

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

42

Carcinoembryonic antigen family of adhesion molecules in the cotton top tamarin ( Saguinus oedipus)  

Microsoft Academic Search

Humans and the cotton top tamarin, a model for colitis and colorectal cancer, share carcinoembryonic antigen (CEA) moieties. We quantified CEA in colonic washings and extracts in both, and CEA bands were confirmed by Western blot. We compared CEA-family expression in tissues and serum in the tamarin with that of the common marmoset, which develops colitis but not cancer. CEA

Martin Tobi; Sreenivas Chintalapani; Karel Kithier; Neal Clapp

2000-01-01

43

Chaos in a Semiclassical Model of Multiphoton Excitation of Spherical Top Molecules.  

National Technical Information Service (NTIS)

We study the dynamical effects of vibration-rotation coupling in multiple photon excitation at lowest order. Our molecular model is the simplest possible: that of an oscillator (triply degenerate) and uncoupled rigid rotor. The molecule-field interactions...

H. W. Galbraith J. R. Ackerhalt P. W. Milonni

1983-01-01

44

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

NASA Astrophysics Data System (ADS)

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+/-11.8cal/mol for (CH3)2O, (CD3)2O, (CH3)2S, (CH3)2SiH2, (CH3)2SiD2, and (CH3)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 (CH3)2O and (CD3)2O which are small but not negligible (V'12=-124.4,-158.0cal/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+/-15.2cal/mol for CH3OCD3 and CH3SCD3. The corrected barrier, V3(CD3) of CH3OCD3, is obtained to be 2634.4+/-7.1cal/mol, while that of CH3SCD3 cannot be solved due to the lack of the data available. It is with great sadness that we report the passing of Professor Emeritus Michiro Hayashi, who died after a short illness on July 9, 2003.

Niide, Yuzuru; Hayashi, Michiro

2004-02-01

45

Chaos in semiclassical model of multiphoton excitation of spherical top molecules  

Microsoft Academic Search

The dynamical effects of vibration-rotation coupling in multiple photon excitation at lowest order using the simplest molecular model possible: that of an oscillator (triply degenerate) and uncoupled rigid rotor. The molecule-field interactions introduce a vibration-rotation nonlinearity which gives rise to nonconservation of the molecular angular momentum and in some instances consequent chaotic dynamics. The chaos leads to incoherence (widely seen

H. W. Galbraith; J. B. Ackerhalt; P. W. Milonni

1983-01-01

46

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

PubMed

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

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

2012-02-23

47

Dynamic phases of vortex-antivortex molecules in a Corbino disk with magnetic dipole on top  

NASA Astrophysics Data System (ADS)

We performed a molecular dynamics study of vortex-antivortex motion in a superconducting disk with a magnetic dot on top, in the Corbino disk geometry. In this system, vortices and antivortices are forced to move in opposite azimuthal directions by a radially applied current. The dot is magnetized out of plane in order to stabilize composite vortex-antivortex configurations, with vortices closer to the center of the disk and antivortices near to the disk edge. We observe that the interplay between the spatially inhomogeneous current distribution, the screening currents induced by the dipole, and the attractive vortex-antivortex (v-av) interaction result in different dynamical phases. At low current values, antivortices - which are distributed at outer rings - remain bounded to vortices at inner rings and the whole configuration rotates rigidly. Above a threshold current, vortices and antivortices unbind and move at different angular velocities in a highly correlated way. Finally, at very strong drive, vortex-antivortex attraction is overhelmed by the external current Lorentz force, causing them to move in opposite directions.

de Aquino, Belisa R. C. H. T.; Cabral, Leonardo R. E.; de Souza Silva, Clécio C.; Albino Aguiar, J.; Miloševi?, Milorad V.; Peeters, François M.

2012-09-01

48

Electrostatic hexapole state-selection of the asymmetric-top molecule propylene oxide: Rotational and orientational distributions  

NASA Astrophysics Data System (ADS)

This theoretical study is complementary to previous experimental work (see D.-C. Che, F. Palazzetti, Y. Okuno, V. Aquilanti, T. Kasai, J. Phys. Chem. A 114 (2010) 3280) on the orientation and rotational state-selection of supersonic molecular beams of the asymmetric-top molecule propylene oxide, both pure and seeded (in He and in Ar) by using an 85-cm length hexapole state-selector. One objective is to obtain an accurate distribution of the rotational states after hexapole selection for the three molecular beams, the most relevant feature consisting in the evaluation of the variation in energy of the manifold of rotational states when an electric field is applied (the Stark forces). Previously, the Stark effect on the effective dipole moment was considered through second order for all rotational states, while in this work the energy derivatives of the rotational states with respect to the applied electric field, are obtained accurately by diagonalizing the very large Stark matrices, whose elements depend on the dipole moment components of the molecule. The Stark energies and the corresponding forces were calculated for values of the electric field between 0 and 80 kV cm-1 in steps of 0.5 kV cm-1 and then linearly interpolated, covering the whole experimental range of the hexapole. A treatment is given for the intricate pattern of avoided crossings among derivatives of the rotational levels and two limiting cases were considered, corresponding to transitions occurring either adiabatically or diabatically. The two treatments lead to slightly different distributions of the rotational states for the pure and Ar seeded molecular beams, while for the He seeded molecular beam the two distributions are substantially the same. This experimental arrangement is a perspective tool for experiments of photochemistry and scattering of oriented molecules and clusters, and therefore we calculated the orientational distributions in a configuration where a uniform electric field is placed between the hexapole field and the detector.

Che, Dock-Chil; Kanda, Keita; Palazzetti, Federico; Aquilanti, Vincenzo; Kasai, Toshio

2012-05-01

49

A new graphical version of STROTAB: The analysis and fitting of singlet triplet spectra of asymmetric top molecules in the prolate or oblate limits  

NASA Astrophysics Data System (ADS)

The original version of STROTAB has been modified to run under Microsoft Windows using the C++ programming language. The new version takes full advantage of the Microsoft Foundation Classes available within the Microsoft Visual C++ Version 6 development environment. Specifically, windows can be created that edit the input file, summarize the results of the least-squares fit, display the calculated and observed spectra, display whole or partial sections of the calculated spectra as a stick or Gaussian de-convoluted spectrum. A listing of the rotational quantum numbers in the cases (a) and (b) limits for each of the displayed lines is provided. A branch annotating routine provides a quick visual guide to the assignment of the spectrum. A new eigenvalue sorting method has been added as an option that complements the existing method based on the eigenvector coefficients. The new sorting method has eliminated some difficulties that may arise using the existing “Least Ambiguous Method”. The program has been extended to handle near-oblate asymmetric tops using a type IIIr representation.New version summaryTitle of program: STROTAB Version number: 2 Catalogue identifier:ADCA_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADCA_v2_0 Program obtainable from:CPC Program Library, Queen's University of Belfast, N. Ireland Reference in CPC to previous version: 93 (1996) 241 264 Catalog identifier of previous version: ADCA Authors of previous version: R.H. Judge, E.D. Womeldorf, R.A. Morris, D.E. Shimp, D.J. Clouthier, D.L. Joo, D.C. Moule Does the new version supersede the original program: Yes Computers for which the program is designed and others on which it has been tested: Pentium Xenon, Pentium Pro and Later Operating systems or monitors under which program has been tested: Windows 98, Windows 2000, Windows XP Programming language used in the new version: ANSI C, C++, Microsoft Foundation Class (MFC) No. of lines in distributed program, including test data, etc.:11?913 No. of bytes in distributed program, including test data, etc.: 2?816?652 Memory required to execute with typical data: 7 Meg No of bits in a word: 16 No of processors used: 1 Has the code been vectorized or parallelized?: No No. of bytes in distributed program, including test data, etc.: ˜3.2 MB (compressed) Distribution format: zip file Additional keywords:near oblate top, bootstrap eigenvalue sorting, graphical environment, band contour Nature of physical problem: The least-squares/band contour fitting of the singlet triplet spectra of asymmetric tops of orthorhombic symmetry using a basis set appropriate to the symmetric top limit (prolate or oblate) of the molecule in either Hund's case (a) or case (b) coupling situations. Method of solution: The calculation of the eigenvectors and eigenvalues remains unchanged from the earlier version. An option to sort the eigenvalues of the current J by fitting them to regular progressions formed from earlier J values (bootstrap method) can be used as an option in place of the existing method based on eigenvector coefficients. Reasons for the new version: The earlier version can only handle oblate tops by diagonalizing using the prolate limit. This has turned out to be unacceptable. An improved method of sorting eigenvalues under certain conditions is also needed. A graphical interface has been added to ease the use of the program. Summary of revisions: The Hamiltonian can now be constructed in a limit appropriate the representation for of the molecule. Sorting by an alternate method is now offered. Numerous graphical features have been added. Restrictions on complexity of the problem: The rotational quantum number restrictions are J?255 and K (or P) ?127. The allowed transition frequency minus the band origin frequency must be in the range of ±10?000 cm-1. Up to five decimal places may be reported. The number of observed lines is limited by the dynamic memory and the amount of disk space available. Only molecules of symmetry D2h, D2 and C2v can be accommodated in this version. Only constants of

Kodet, John; Judge, Richard H.

2007-05-01

50

Asymmetric-top molecules containing one methyl-like internal rotor: Methods and codes for fitting and predicting spectra  

NASA Astrophysics Data System (ADS)

This paper is a review of various effective Hamiltonians, methods and codes dealing with asymmetric-top molecules containing one internal rotor with C3v (or close to C3v) symmetry. It aims at helping high-resolution spectroscopists to find the most appropriate method(s) and code(s) to assign and fit their internal rotor spectra. The topics included are: description of some of the available effective Hamiltonians, methods (PAM, Principal Axis Method, RAM, Rho-Axis Method and IAM, Internal-Axis Method) and codes to deal with internal rotor spectra (JB95, ERHAM, XIAM, SPFIT/SPCAT/IAMCALC and BELGI). The methods are also classified by the way they are dealing with the set of torsional states associated with the internal rotation large amplitude motion: globally or locally. Examples are given of internal rotors treated by each of those codes with root-mean-square deviations, Jmax, torsional bath levels involved, and parameters obtained to allow the reader to choose the appropriate method for his study. More details are given for the RAM method used in BELGI, with series of examples. Some user-manual-like hints for running the fits are also given.

Kleiner, I.

2010-03-01

51

Species Classification and Rotational Energy Level Patterns of Non-Linear Triatomic Molecules  

Microsoft Academic Search

With the object of making existing knowledge more readily available, the quantized energy levels of symmetrical and asymmetrical tops are discussed from the viewpoint of their classification into species defined by symmetry operations; and simple species nomenclatures are proposed. These are then applied in a discussion of the rotational levels of symmetrical non-linear triatomic molecules AB2. With SO2 as an

Robert S. Mulliken

1941-01-01

52

Enhanced ionization of the non-symmetric HeH(+) molecule driven by intense ultrashort laser pulses.  

PubMed

We study enhanced single and double ionizations and enhanced single and double excitations in the nonsymmetric two-electron diatomic molecular ion HeH(+) in an intense ultrashort laser pulse linearly polarized along the internuclear axis (z axis). We solve a three-dimensional time-dependent Schro?dinger 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 Rc and decrease by further increase of R. This enhanced ionization (EI) at Rc 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 Rc at which the enhancement of all these molecular processes happens in HeH(+) from a simple quasistatic model and investigate the effect of Carrier Envelope Phase on these nonlinear nonperturbative processes. PMID:24007005

Dehghanian, E; Bandrauk, A D; Lagmago Kamta, G

2013-08-28

53

Enhanced ionization of the non-symmetric HeH+ molecule driven by intense ultrashort laser pulses  

NASA Astrophysics Data System (ADS)

We study enhanced single and double ionizations and enhanced single and double excitations in the nonsymmetric two-electron diatomic molecular ion HeH+ 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 Rc and decrease by further increase of R. This enhanced ionization (EI) at Rc 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 Rc at which the enhancement of all these molecular processes happens in HeH+ from a simple quasistatic model and investigate the effect of Carrier Envelope Phase on these nonlinear nonperturbative processes.

Dehghanian, E.; Bandrauk, A. D.; Lagmago Kamta, G.

2013-08-01

54

C2v top data system (C2v TDS) software for infrared spectrum simulation of XY2Z2 asymmetric molecules: some improvements to the TDS packages  

NASA Astrophysics Data System (ADS)

The spherical top data system (STDS) program suite developed in Dijon has been extended with the aim of studying any rovibrational band or polyad of XY2Z2(C2v) asymmetric top molecules. We work in the O(3)?Td?C2v chain because these species result from the substitution of two ligands of a corresponding “parent” spherical top and thus are relatively close to tetrahedral symmetry. The choice of this group chain has consequences on the method used to specify the input parameters of the programs for Hamiltonian and transition moment model calculations. One example concerning the ground state of the SO2F2 quasi-spherical molecule is presented. As before, this suite consists in a series of FORTRAN programs called by a script. The whole package is freely accessible through ftp (user anonymous) at jupiter.u-bourgogne.fr/dist or through the World Wide Web at http://www.u-bourgogne.fr/LPUB/c2vTDS.html. Further general improvements have been brought about for all the TDS packages (STDS, HTDS, C4vTDS) developed in our group and are briefly discussed in the present paper.

Wenger, Ch.; Rotger, M.; Boudon, V.

2005-07-01

55

Orientation-dependent ionization yields from strong-field ionization of fixed-in-space linear and asymmetric top molecules  

NASA Astrophysics Data System (ADS)

The yield of strong-field ionization, by a linearly polarized probe pulse, is studied experimentally and theoretically as a function of the relative orientation between the laser field and the molecule. Experimentally, carbonyl sulphide (OCS), benzonitrile and naphthalene molecules are aligned in one or three dimensions before being singly ionized by a 30 fs laser pulse centred at 800 nm. Theoretically, we address the behaviour of these three molecules. We consider the degree of alignment and orientation and model the angular dependence of the total ionization yield by molecular tunnelling theory accounting for the Stark shift of the energy level of the ionizing orbital. For naphthalene and benzonitrile, the orientational dependence of the ionization yield agrees well with the calculated results, in particular, we observe that ionization is maximized when the probe laser is polarized along the most polarizable axis. For OCS the observation of the maximum ionization yield when the probe is perpendicular to the internuclear axis contrasts the theoretical results.

Hansen, Jonas L.; Holmegaard, Lotte; Nielsen, Jens H.; Stapelfeldt, Henrik; Dimitrovski, Darko; Bojer Madsen, Lars

2012-01-01

56

Orientation-dependent ionization yields from strong-field ionization of fixed-in-space linear and asymmetric top molecules  

NASA Astrophysics Data System (ADS)

The ionization step leading to single ionization in the multiphoton or tunnel ionization regime is a fundamental process which is thought to be well understood for atoms; however, for larger molecules much less is known. Of particular importance is the understanding of the dependence of the initial ionization step on the molecular orientation with respect to the external field. To fully test existing theories and to guide the way for new theory development, we here extend these experiments to larger and more complex molecular systems: Carbonyl sulphide (OCS), benzonitrile and naphthalene. In particular we investigate the yield of strong-field ionization, by a linearly polarized probe pulse, as a function of the relative orientation between the laser field and the molecule. This is achieved using standard laser alignment techniques to produce 1D or 3D aligned molecular ensembles before a femtosecond laser probe pulse singly ionizes the target molecules. For naphthalene and benzonitrile, the orientational dependence of the ionization yield agrees well with the calculated results, in particular, we observe that ionization is maximized when the probe laser is polarized along the most polarizable axis. For OCS the observation of the maximum ionization yield when the probe is perpendicular to the internuclear axis contrasts the theoretical results.

Hansen, J. L.; Dimitrovski, D.; Madsen, L. B.; Stapelfeldt, H.

2012-06-01

57

Symmetric textures  

SciTech Connect

The Wolfenstein parametrization is extended to the quark masses in the deep ultraviolet, and an algorithm to derive symmetric textures which are compatible with existing data is developed. It is found that there are only five such textures.

Ramond, P. (Florida Univ., Gainesville, FL (United States). Dept. of Physics)

1993-01-01

58

Symmetric textures  

SciTech Connect

The Wolfenstein parametrization is extended to the quark masses in the deep ultraviolet, and an algorithm to derive symmetric textures which are compatible with existing data is developed. It is found that there are only five such textures.

Ramond, P. [Florida Univ., Gainesville, FL (United States). Dept. of Physics

1993-04-01

59

Photodissociation of Oriented Molecule Beams and Reactive Scattering  

NASA Astrophysics Data System (ADS)

The requirement of proper mutual orientation of reagents is second only to the energy requirement for chemical reaction to take place. Since the introduction of hexapole field focusing and orientation of symmetric-top molecule in 1965, considerable insight has been gained on the role of orientation in reactive scattering dynamics. To achieve a more quantitative understanding of the steric effect in reactive scattering, a pulsed supersonic molecular beam machine with a 3-meter long, electrostatic hexapole field has been constructed. Focusing and rotational state selection has been achieved for prolate symmetric-top molecules, such as CH_3X (X = F, Cl, Br and I). Partial state selection has been achieved for oblate symmetric-top molecules. Various polar asymmetric top molecules have also been focused, as well as the pseudo -symmetric tops, (CH_3)_3 CI and (CH_3)_3 CBr. These molecules have been studied in some detail. They have been focused and oriented with a homogeneous field. The degree of laboratory orientation has been measured for the first time with a newly developed polarized laser photofragmentation technique. It is found that the goodness of orientation achievable has the following sequence: (CH_3 )_3CBr > (CH_3)_3CI > CH_3I. Various techniques of producing reactive atomic beams have been explored and tested, including a seeded supersonic nozzle metal beam source, a seeded laser evaporation metal beam source, a Cl atom source utilizing microwave discharge, and an effusive metal beam oven. The effusive oven of Sr produces very stable beams and has therefore been used in a study of the crossed beam reaction of Sr + CH_3I. In order to detect weak product signal (SrI) from the crossed-beam reaction, a sensitive detection technique has been developed utilizing single photon ionization of SrI with 193 nm excimer laser radiation and time-of-flight mass spectrometry. The SrI^{+} signal is readily detected. The much stronger Sr^{+} ion beam (from the photoionization of the Sr reagent) is deflected by a gated high voltage pulse. By changing the carrier gas of the seeded, pulsed CH_3I beam to achieve different collision energies, the excitation function of Sr + CH_3I reaction has been measured. The reaction threshold is estimated to be 0.07 +/- 0.02 eV, in accord with expectation based on analogous reactions and semi -empirical theory.

Xu, Qixun

60

Top studies  

SciTech Connect

The top quark, discovered in 1994 at the Tevatron, has proven a very interesting particle. Its characteristics allow both to perform stringent tests of electroweak theory, and to search for new physics through a deviation from standard model predictions for several of its peculiar properties. I will review the status of top physics and briefly describe the potential of experiments of the near future.

T. Dorigo

2003-01-02

61

Symmetry selection rules in rotationally inelastic collisions of open-shell diatomic molecules and polyatomic tops: Implications of an irreducible tensor expansion  

SciTech Connect

An irreducible tensor formalism due to Grawert is applied to collisions of open-shell diatomics and polyatomic tops. Explicit examination of the reduced T-matrix elements within the infinite-order sudden and first-order Born limits allows the derivation of several general symmetry selection rules for a rotationally inelastic process. In particular, both differential and integral cross sections will vanish unless the symmetry indices of the initial and final states satisfy certain conditions, for the following types of transitions: J = 0..-->..J'M'; J,M = 0..-->..J',M' = 0; and JM..-->..J,-M. The M = 0..-->..M' = 0 selection rule represents the extension, to an arbitrary orientation of the quantization axis, of a selection rule we have derived earlier. A comparison with results of fully quantum studies of collisions of NH/sub 3/ and H/sub 2/CO with He confirms the predictive accuracy of these rules. We discuss how both the M = 0..-->..M' = 0 and JM..-->..J,-M selection rules could be directly verified, in experiments involving laser excitation of a particular symmetry level followed by resolution of the fluorescence polarization.

Alexander, M.H.; Davis, S.L.

1983-07-01

62

Architectural Tops  

ERIC Educational Resources Information Center

|The development of the skyscraper is an American story that combines architectural history, economic power, and technological achievement. Each city in the United States can be identified by the profile of its buildings. The design of the tops of skyscrapers was the inspiration for the students in the author's high-school ceramic class to develop…

Mahoney, Ellen

2010-01-01

63

Scaling model for symmetric star polymers  

Microsoft Academic Search

Neutron scattering data from symmetric star polymers with six poly (urethane-ether) arms, chemically bonded to a C-60 molecule are fitted using a new scaling model and scattering function. The new scaling function can describe both good solvent and theta solvent conditions as well as resolve deviations in chain conformation due to steric interactions between star arms. The scaling model quantifies

Ram Ramachandran; Durgesh K. Rai; Gregory Beaucage

2010-01-01

64

Symmetric Continued Fractions  

NASA Astrophysics Data System (ADS)

Explicit formulae for continued fractions with symmetric patterns in their partial quotients are constructed in the field of formal power series. Similar to the work of Cohn in 1996, which generalized the so-called folding lemma to ?-fold symmetry, the notion of ?-duplicating symmetric continued fractions is investigated using a modification of the 1995 technique due to Clemens, Merrill and Roeder.

Panprasitwech, Oranit; Laohakosol, Vichian; Chaichana, Tuangrat

2010-11-01

65

Einstein A-values for purely rotational transitions in the HDO-molecule  

NASA Astrophysics Data System (ADS)

IR values were included in a nonlinear transfer of energy analysis of Einstein A-values for purely rotational transitions between levels up to 1000/cm in the ground vibrational state of the HDO molecule. Rotational wave functions of the HDO molecule were described by combinations of the symmetric top wave functions. Consideration was focused on the electric dipole moment Debye length on the a-axis of inertia and a formulation was defined for its corresponding line strength. The transition probabilities are derived from the line strengths and then the A-values are calculated. The A-values are used to project mean radiative lifetimes for the levels.

Chandra, S.; Kegel, W. H.; Varshalovich, D. A.

1984-12-01

66

Noncommutative spherically symmetric spaces  

SciTech Connect

We examine some noncommutative spherically symmetric spaces in three space dimensions. A generalization of Snyder's noncommutative (Euclidean) space allows the inclusion of the generator of dilations into the defining algebra of the coordinate and rotation operators. We then construct a spherically symmetric noncommutative Laplacian on this space having the correct limiting spectrum. This is presented via a creation and annihilation operator realization of the algebra, which may lend itself to a truncation of the Hilbert space.

Murray, Sean; Govaerts, Jan [Centre for Cosmology, Particle Physics and Phenomenology, Universite catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve (Belgium); Centre for Cosmology, Particle Physics and Phenomenology, Universite catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve (Belgium) and International Chair in Mathematical Physics and Applications, University of Abomey-Calavi, 072 B. P. 50, Cotonou (Benin)

2011-01-15

67

The symmetric parabolic resonance  

NASA Astrophysics Data System (ADS)

The parabolic resonance instability emerges in diverse applications ranging from optical systems to simple mechanical ones. It appears persistently in p-parameter families of near-integrable Hamiltonian systems with n degrees of freedom provided n + p >= 3. Here we study the simplest (n = 2, p = 1) symmetric case. The structure and the phase-space volume of the corresponding instability zones are characterized. It is shown that the symmetric case has six distinct non-degenerate normal forms, and two degenerate ones. In the regular cases, the instability zone has the usual O(\\sqrt{\\varepsilon}) extent in the action direction. However, the phase-space volume of this zone is found to be polynomial in the perturbation parameter ? (and not exponentially small as in the elliptic resonance case). Finally, the extent of the instability zone in some of the degenerate cases is explored. Three applications in which the symmetric parabolic resonance arises are presented and analysed.

Rom-Kedar, V.; Turaev, D.

2010-06-01

68

Braids, shuffles and symmetrizers  

NASA Astrophysics Data System (ADS)

Multiplicative analogues of the shuffle elements of the braid group rings are introduced; in local representations they give rise to certain graded associative algebras (b-shuffle algebras). For the Hecke and BMW algebras, the (anti)-symmetrizers have simple expressions in terms of the multiplicative shuffles. The (anti)-symmetrizers can be expressed in terms of the highest multiplicative 1-shuffles (for the Hecke and BMW algebras) and in terms of the highest additive 1-shuffles (for the Hecke algebras). The spectra and multiplicities of eigenvalues of the operators of the multiplication by the multiplicative and additive 1-shuffles are examined. Dedicated to the memory of Aleosha Zamolodchikov.

Isaev, A. P.; Ogievetsky, O. V.

2009-07-01

69

Isomorphic Steiner symmetrization  

Microsoft Academic Search

This paper proves that there exist 3 n Steiner symmetrizations that transform any convex set K?R n into an isomorphic Euclidean ball; i.e. if vol( K)= vol( D n) where D n is the standard Euclidean unit ball, then K can be transformed into a body K such that c 1 D n? K? c 2 D n, where c

B. Klartag; V. D. Milman

2003-01-01

70

Classical symmetric functions in superspace  

Microsoft Academic Search

We present the basic elements of a generalization of symmetric function theory involving functions of commuting and anticommuting (Grassmannian) variables. These new functions, called symmetric functions in superspace, are invariant under the diagonal action of the symmetric group on the sets of commuting and anticommuting variables. In this work, we present the superspace extension of the classical bases, namely, the

Patrick Desrosiers; Luc Lapointe; Pierre Mathieu

2006-01-01

71

Properties of Symmetric Fitness Functions  

Microsoft Academic Search

The properties of symmetric fitness functions are investigated. We show that the search spaces obtained from symmetric functions have the zero-correlation structures between fitness and distance. It is also proven that symmetric functions induce a class of the hardest problems in terms of the epistasis variance and its variants. These analyses suggest that the existing quantitative measures cannot discriminate among

Sung-soon Choi; Yung-keun Kwon; Byung-Ro Moon

2007-01-01

72

Buckets of tops  

NASA Astrophysics Data System (ADS)

Reconstructing hadronically decaying top quarks is a key challenge at the LHC, affecting a long list of Higgs analyses and new physics searches. We propose a new method of collecting jets in buckets, corresponding to top quarks and initial state radiation. This method is particularly well suited for moderate transverse momenta of the top quark, closing the gap between top taggers and traditional top reconstruction. Applying it to searches for supersymmetric top squarks we illustrate the power of buckets.

Buckley, Matthew R.; Plehn, Tilman; Takeuchi, Michihisa

2013-08-01

73

Chemical routes to top-down nanofabrication.  

PubMed

In fabricating materials at the nanometer scale, nanotechnologists typically employ two general strategies: bottom-up and top-down. While the bottom-up approach constructs nanomaterials from basic building blocks like atoms or molecules, the top-down approach produces nanostructures by deconstructing larger materials with the use of lithographic tools (i.e., physical top-down) or through chemical-based processes (i.e., chemical top-down). This tutorial review summarizes the various top-down nanofabrication methods, with great emphasis on the chemical routes that can generate nanoporous materials and ordered arrays of nanostructures with three-dimensional features. The chemical top-down routes that are discussed in detail include (1) templated etching, (2) selective dealloying, (3) anisotropic dissolution, and (4) thermal decomposition. These emerging nanofabrication tools open up new avenues in the creation of functional nanostructures with a wide array of promising applications. PMID:23653019

Yu, Hai-Dong; Regulacio, Michelle D; Ye, Enyi; Han, Ming-Yong

2013-07-21

74

Top physics at CDF  

SciTech Connect

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.

Julia Thom

2004-06-24

75

Tevatron top physics  

SciTech Connect

A summary of the most recent results on top quark physics obtained at Fermilab's Tevatron proton-antiproton collider, operating at a centre of mass energy of 1.96 TeV, is presented. Measurements of the top pair and single top quark production cross sections, the investigation of top quark decay properties, the precision measurement of the top quark mass as well as searches for physics beyond the standard model are discussed.

Wagner-Kuhr, Jeannine; /Karlsruhe U.

2009-04-01

76

Theoretical Study of the Binding of Positrons of Gaseous Molecules.  

National Technical Information Service (NTIS)

While a positron will not readily become attached to a neutral symmetrical atom or molecule, it will be bound by negatively charged molecules and molecular fragments. The positron affinities have been calculated for certain isoelectronic series using a Ha...

A. B. Kunz J. T. Waber

1982-01-01

77

Top quark physics  

SciTech Connect

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.

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

2000-03-24

78

A Thermodynamic Model of Phosphorus Distribution Ratio between CaO-SiO 2 -MgO-FeO-Fe 2 O 3 -MnO-Al 2 O 3 -P 2 O 5 Slags and Molten Steel during a Top–Bottom Combined Blown Converter Steelmaking Process Based on the Ion and Molecule Coexistence Theory  

Microsoft Academic Search

A thermodynamic model for calculating the phosphorus distribution ratio between top–bottom combined blown converter steelmaking\\u000a slags and molten steel has been developed by coupling with a developed thermodynamic model for calculating mass action concentrations\\u000a of structural units in the slags, i.e., CaO-SiO2-MgO-FeO-Fe2O3-MnO-Al2O3-P2O5 slags, based on the ion and molecule coexistence theory (IMCT). Not only the total phosphorus distribution ratio but

Xue-Min Yang; Jian-Ping Duan; Cheng-Bin Shi; Meng Zhang; Yong-Liang Zhang; Jian-Chang Wang

2011-01-01

79

Tinkering with Tops  

NSDL National Science Digital Library

In this activity, learners explore the history, design and motion of spinning tops. Learners work in teams of "engineers" to design and build their own tops out of everyday items. Their challenge is to design a spinning top that can spin for at least 10 seconds within a circle 30 cm in diameter.

Ieee

2013-07-08

80

Spherical Tippe Tops  

ERIC Educational Resources Information Center

|A tippe top (see Fig. 1) is usually constructed as a truncated sphere with a cylindrical peg on top, as indicated in Fig. 2(a). When spun rapidly on a horizontal surface, a tippe top spins about a vertical axis while rotating slowly about a horizontal axis until the peg touches the surface. At that point, weight is transferred to the peg, the…

Cross, Rod

2013-01-01

81

Dare We Teach Tops?  

ERIC Educational Resources Information Center

|"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…

Featonby, David

2010-01-01

82

Spherical Tippe Tops  

ERIC Educational Resources Information Center

A tippe top (see Fig. 1) is usually constructed as a truncated sphere with a cylindrical peg on top, as indicated in Fig. 2(a). When spun rapidly on a horizontal surface, a tippe top spins about a vertical axis while rotating slowly about a horizontal axis until the peg touches the surface. At that point, weight is transferred to the peg, the…

Cross, Rod

2013-01-01

83

Conformally symmetric traversable wormholes  

SciTech Connect

Exact solutions of traversable wormholes are found under the assumption of spherical symmetry and the existence of a nonstatic conformal symmetry, which presents a more systematic approach in searching for exact wormhole solutions. In this work, a wide variety of solutions are deduced by considering choices for the form function, a specific linear equation of state relating the energy density and the pressure anisotropy, and various phantom wormhole geometries are explored. A large class of solutions impose that the spatial distribution of the exotic matter is restricted to the throat neighborhood, with a cutoff of the stress-energy tensor at a finite junction interface, although asymptotically flat exact solutions are also found. Using the 'volume integral quantifier', it is found that the conformally symmetric phantom wormhole geometries may, in principle, be constructed by infinitesimally small amounts of averaged null energy condition violating matter. Considering the tidal acceleration traversability conditions for the phantom wormhole geometry, specific wormhole dimensions and the traversal velocity are also deduced.

Boehmer, Christian G.; Harko, Tiberiu; Lobo, Francisco S. N. [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 2EG (United Kingdom); Department of Physics and Center for Theoretical and Computational Physics, University of Hong Kong, Pok Fu Lam Road, Hong Kong (China); Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 2EG, United Kingdom and Centro de Astronomia e Astrofisica da Universidade de Lisboa, Campo Grande, Ed. C8 1749-016 Lisbon (Portugal)

2007-10-15

84

Achromatic axially symmetric wave plate.  

PubMed

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

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

2012-12-31

85

Photoinduced localization and decoherence in inversion symmetric molecules  

Microsoft Academic Search

Coherence of particles in form of matter waves is one of the basic properties of nature which distinguishes classical from quantum behavior. This is a direct consequence of the particle–wave dualism. It is the wave-like nature, which gives rise to coherence, whereas particle-like behavior results from decoherence. If two quantum objects are coherently coupled with respect to a particular variable,

Burkhard Langer; Kiyoshi Ueda; Omar M. Al-Dossary; Uwe Becker

2011-01-01

86

Progressive symmetrical erythrokeratodermia -- case report*.  

PubMed

Progressive symmetrical erythrokeratodermia is a rare autosomal dominant genodermatosis with variable penetrance described by Darier in 1911. It is characterized by erythematous and keratotic plaques, sharply defined and symmetrically distributed along the extremities, buttocks and, more rarely, on the face. We report a case of a 55-year-old patient with lesions on the dorsum of the hands, interphalangeal pads, wrists, groin and back feet. This case demonstrates a rare and late diagnosis, clinical profusion and presence of familiar involvement. PMID:23539014

Guaraldi, Bianca de Mello; Jaime, Thaís Jerez; Guaraldi, Rafael de Mello; Melo, Daniel Fernandes; Nogueira, Osvania Maris; Rodrigues, Nilton

87

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

SciTech Connect

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.

J Lee; M Blaber

2011-12-31

88

Top Physics at CDF  

SciTech Connect

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.

Moon, Chang-Seong

2011-06-01

89

Polariton Condensation in Photonic Molecules  

NASA Astrophysics Data System (ADS)

We report on polariton condensation in photonic molecules formed by two coupled micropillars. We show that the condensation process is strongly affected by the interaction with the cloud of uncondensed excitons and thus strongly depends on the exact localization of these excitons within the molecule. Under symmetric excitation conditions, condensation is triggered on both binding and antibinding polariton states of the molecule. On the opposite, when the excitonic cloud is injected in one of the two pillars, condensation on a metastable state is observed and a total transfer of the condensate into one of the micropillars can be achieved. Our results highlight the crucial role played by relaxation kinetics in the condensation process.

Galbiati, Marta; Ferrier, Lydie; Solnyshkov, Dmitry D.; Tanese, Dimitrii; Wertz, Esther; Amo, Alberto; Abbarchi, Marco; Senellart, Pascale; Sagnes, Isabelle; Lemaître, Aristide; Galopin, Elisabeth; Malpuech, Guillaume; Bloch, Jacqueline

2012-03-01

90

Is Symmetrical Communication Ethical and Effective?  

Microsoft Academic Search

The purpose of this paper is to explore two questions:(1) Is symmetrical communication in public relations practice inherently ethical?(2) Does symmetrical communication contribute to public relations effectiveness and organizational effectiveness? Three surveys are undertaken to test seven research hypotheses for the purpose of cross-validating research findings. The results suggest that symmetrical communication is inherently ethical. Moreover, symmetrical communication indeed contributes

Yi-Hui Huang

2004-01-01

91

Top search at CDF  

SciTech Connect

We review top quark searches carried out at CDF with data collected during the 1988--1989 Collider Run. The latest analyses give a lower limit on the top quark mass of 91 GeV/c{sup 2} at the 95% confidence level, assuming Standard Model decays. 8 refs., 6 figs., 1 tab.

Contreras, M. [Chicago Univ., IL (United States); The CDF Collaboration

1991-10-01

92

Top-Level Structures  

ERIC Educational Resources Information Center

In this article, the author discusses top-level structure, a form of text structure that would help students improve their reading comprehension. There are four main organizational patterns, or top-level structures, that occur mostly in factual texts: compare/contrast, cause/effect, problem/ solution, and list-like. Authors often use signaling…

Bolton, Faye

2007-01-01

93

Training Top 125  

ERIC Educational Resources Information Center

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…

Training, 2012

2012-01-01

94

Training Top 125  

ERIC Educational Resources Information Center

|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…

Training, 2012

2012-01-01

95

Top-Quark Physics  

Microsoft Academic Search

We survey top-quark physics from what has been learned so far at the Tevatron to the searches planned at present and future colliders. We summarize the richness of the measurements and discuss their possible impact on our understanding of the standard model by pointing out their key elements and limitations. We discuss how the top quark may provide a connection

Dhiman Chakraborty; Jacobo Konigsberg; David Rainwater

2003-01-01

96

Top-Level Structures  

ERIC Educational Resources Information Center

|In this article, the author discusses top-level structure, a form of text structure that would help students improve their reading comprehension. There are four main organizational patterns, or top-level structures, that occur mostly in factual texts: compare/contrast, cause/effect, problem/ solution, and list-like. Authors often use signaling…

Bolton, Faye

2007-01-01

97

Training Top 125  

ERIC Educational Resources Information Center

|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…

Training, 2011

2011-01-01

98

Training Top 125  

ERIC Educational Resources Information Center

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…

Training, 2011

2011-01-01

99

Scaling model for symmetric star polymers  

NASA Astrophysics Data System (ADS)

Neutron scattering data from symmetric star polymers with six poly (urethane-ether) arms, chemically bonded to a C-60 molecule are fitted using a new scaling model and scattering function. The new scaling function can describe both good solvent and theta solvent conditions as well as resolve deviations in chain conformation due to steric interactions between star arms. The scaling model quantifies the distinction between invariant topological features for this star polymer and chain tortuosity which changes with goodness of solvent and steric interaction. Beaucage G, Phys. Rev. E 70 031401 (2004).; Ramachandran R, et al. Macromolecules 41 9802-9806 (2008).; Ramachandran R, et al. Macromolecules, 42 4746-4750 (2009); Rai DK et al. Europhys. Lett., (Submitted 10/2009).

Ramachandran, Ram; Rai, Durgesh K.; Beaucage, Gregory

2010-03-01

100

New non-symmetrical choline kinase inhibitors.  

PubMed

Identification of novel and selective anticancer agents remains an important and challenging goal in pharmacological research. Choline kinase (ChoK) is the first enzyme in the CDP-choline pathway that synthesizes phosphatidylcholine (PC), the major phospholipid in eukaryotic cell membranes. In the present paper, a new family of non-symmetrical monocationic compounds is developed including a 3-aminophenol moiety, bound to 4-(dimethylamino)- or 4-(pyrrolidin-1-yl)pyridinium cationic heads through several linkers. The most promising compounds in these series as ChoK inhibitors are 3f and 4f, while compounds 3c, 3d and 4c are the better antiproliferative agents. The analysis of the biological data observed in the described series of compounds mays represents a platform for the design of more active molecules. PMID:24080101

Schiaffino-Ortega, Santiago; López-Cara, Luisa Carlota; Ríos-Marco, Pablo; Carrasco-Jimenez, Maria Paz; Gallo, Miguel A; Espinosa, Antonio; Marco, Carmen; Entrena, Antonio

2013-09-11

101

Molecule Shapes  

NSDL National Science Digital Library

Explore molecule shapes by building molecules in 3D! How does molecule shape change with different numbers of bonds and electron pairs? Find out by adding single, double or triple bonds and lone pairs to the central atom. Then, compare the model to real molecules!

Simulations, Phet I.; Moore, Emily; Olson, Jonathan; Lancaster, Kelly; Chamberlain, Julia; Perkins, Kathy

2011-10-10

102

Looking for symmetric Bell inequalities  

NASA Astrophysics Data System (ADS)

Finding all Bell inequalities for a given number of parties, measurement settings and measurement outcomes is in general a computationally hard task. We show that all Bell inequalities which are symmetric under the exchange of parties can be found by examining a symmetrized polytope which is simpler than the full Bell polytope. As an illustration of our method, we generate 238 885 new Bell inequalities and 1085 new Svetlichny inequalities. We find, in particular, facet inequalities for Bell experiments involving two parties and two measurement settings that are not of the Collins-Gisin-Linden-Massar-Popescu type.

Bancal, Jean-Daniel; Gisin, Nicolas; Pironio, Stefano

2010-09-01

103

Top Quark Properties  

SciTech Connect

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.

Peters, Yvonne

2011-12-01

104

Top Quark Mass Measurements  

SciTech Connect

First observed in 1995, the top quark is one of a pair of third-generation quarks in the Standard Model of particle physics. It has charge +2/3e and a mass of 171.4 GeV, about 40 times heavier than its partner, the bottom quark. The CDF and DO collaborations have identified several hundred events containing the decays of top-antitop pairs in the large dataset collected at the Tevatron proton-antiproton collider over the last four years. They have used these events to measure the top quark's mass to nearly 1% precision and to study other top quark properties. The mass of the top quark is a fundamental parameter of the Standard Model, and knowledge of its value with small uncertainty allows us to predict properties of the as-yet-unobserved Higgs boson. This paper presents the status of the measurements of the top quark mass. It is based on a talk I gave at the Conference on the Intersections of Particle and Nuclear Physics in Puerto Rico, May 2006, which also included discussion of measurements of other top quark properties.

Heinson, A. P. [Department of Physics and Astronomy, University of California, Riverside, CA 92521-0413 (United States)

2006-11-17

105

Top physics at CDF  

SciTech Connect

The top quark is 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 (SM). This article focuses on the latest top physics results from CDF based on 320-750 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 also searched for massive t{bar t} resonances.

Palencia, Enrique; /Cantabria Inst. of Phys.

2006-06-01

106

A note on symmetric connections  

NASA Astrophysics Data System (ADS)

In this paper we analyze a reciprocal of the fundamental theorem of Riemannian geometry. We give a condition for a symmetric connection to be locally the Levi-Civita connection of a metric. We also construct a couple of natural examples of connections on the n-dimensional torus and investigate the global problem.

Cocos, M.

2006-03-01

107

Shearfree Spherically Symmetric Fluid Models  

NASA Astrophysics Data System (ADS)

We attempt to discover some exact analytical models of the spherically symmetric spacetime of collapsing fluid under shearfree conditions. Two types of solution are considered: one is to impose a condition on the mass function, while the other is to restrict the pressure. We obtain five exact models in total, and some of them satisfy the Darmois conditions.

Sharif, M.; Yousaf, Z.

2012-05-01

108

Response matrix of symmetric nodes  

Microsoft Academic Search

Properties of a symmetric node's response matrix are discussed. The node may have an internal structure such that it remains invariant under the symmetry transformations of the considered node. A transformation diagonalizing the response matrix is given by means of symmetry considerations. The equivalence is demonstrated of the response matrix method to a finite difference scheme in which the dependent

Makai

1984-01-01

109

Dare we teach tops?  

NASA Astrophysics Data System (ADS)

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.

Featonby, David

2010-07-01

110

Top quark mass measurements  

SciTech Connect

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.

Hill, Christopher S.; /UC, Santa Barbara

2004-12-01

111

Molecule nanoweaver  

DOEpatents

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.

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

112

Symmetric functions and P-recursiveness  

Microsoft Academic Search

Many enumeration problems, such as that of counting nonnegative integer matrices with given row and column sums, have solutions which can be expressed as coefficients of symmetric functions. We show here how useful formulas can be obtained from these symmetric function generating functions. In some cases, the symmetric functions yield reasonably simple explicit formulas or generating functions for the coefficients.

Ira M. Gessel

1990-01-01

113

Range Symmetric Matrices in Minkowski Space  

Microsoft Academic Search

The concept of range symmetric matrix is introduced in Minkowski space m. Equivalent conditions for a matrix to be range symmetric are determined. The existence of the Minkowski inverse of a range symmetric matrix in m is discussed. ? = n u u u u u L Let G be the Minkowski metric tensor defined by . ) , ,

A. R. MEENAKSHI

2000-01-01

114

DNA Security using Symmetric and Asymmetric Cryptography  

Microsoft Academic Search

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

L. Alboaie L. Chiorean M. Vaida Radu Terec

2011-01-01

115

DNA Security using Symmetric and Asymmetric Cryptography  

Microsoft Academic Search

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

Radu Terec; MirceaFlorin Vaida; Lenuta Alboaie; Ligia Chiorean

116

Symmetrical Multifoil Shields for reducing Spray Drift  

Microsoft Academic Search

In this study, two symmetrical multi-foil shields were designed to minimise spray drift in both upwind and downwind travel directions. One shield was a symmetrical double foil that induced direct air assist (an air jet acting directly on the spray droplets), while the other shield was a symmetrical triple foil that induced both direct air assist and an air curtain

M. M Sidahmed; H. H Awadalla; M. A Haidar

2004-01-01

117

Symmetric informationally complete quantum measurements  

Microsoft Academic Search

We consider the existence in arbitrary finite dimensions d of a positive operator valued measure (POVM) comprised of d2 rank-one operators all of whose operator inner products are equal. Such a set is called a “symmetric, informationally complete” POVM (SIC–POVM) and is equivalent to a set of d2 equiangular lines in Cd. SIC–POVMs are relevant for quantum state tomography, quantum

Joseph M. Renes; Robin Blume-Kohout; A. J. Scott; Carlton M. Caves

2004-01-01

118

Symmetric Key Authentication Services Revisited  

Microsoft Academic Search

Most of the symmetric key authentication schemes deployed today are based on principles introduced by Needham and Schroeder (17) more than twenty years ago. However, since then, the computing environment has evolved from a LAN-based client-server world to include new paradigms, including wide area networks, peer-to-peer networks, mobile ad-hoc networks and ubiquitous computing. Also, there are new threats, including viruses,

Bruno Crispo; Bogdan C. Popescu; Andrew S. Tanenbaum

2004-01-01

119

Symmetric informationally complete quantum measurements  

Microsoft Academic Search

We consider the existence in arbitrary finite dimensions d of a positive operator valued measure (POVM) comprised of d2 rank-one operators all of whose operator inner products are equal. Such a set is called a ``symmetric, informationally complete'' POVM (SIC-POVM) and is equivalent to a set of d2 equiangular lines in Cd. SIC-POVMs are relevant for quantum state tomography, quantum

Joseph M. Renes; Robin Blume-Kohout; A. J. Scott; Carlton M. Caves

2004-01-01

120

Order-Preserving Symmetric Encryption  

Microsoft Academic Search

We initiate the cryptographic study of order-preserving symmetric encryption (OPE), a prim- itive suggested in the database community by Agrawal et al. (SIGMOD '04) for allowing ecient range queries on encrypted data. Interestingly, we rst show that a straightforward relaxation of standard security notions for encryption such as indistinguishability against chosen-plaintext attack (IND-CPA) is unachievable by a practical OPE scheme.

Alexandra Boldyreva; Nathan Chenette; Younho Lee; Adam O’Neill

2009-01-01

121

Symmetric Auslander and Bass categories  

NASA Astrophysics Data System (ADS)

We define the symmetric Auslander category A^s(R) to consist of complexes of projective modules whose left- and right-tails are equal to the left- and right tails of totally acyclic complexes of projective modules. The symmetric Auslander category contains A(R), the ordinary Auslander category. It is well known that A(R) is intimately related to Gorenstein projective modules, and our main result is that A^s(R) is similarly related to what can reasonably be called Gorenstein projective homomorphisms. Namely, there is an equivalence of triangulated categories: \\underline{GMor}(R) --> A^s(R) / K^b(Prj R). Here \\underline{GMor}(R) is the stable category of Gorenstein projective objects in the abelian category Mor(R) of homomorphisms of R-modules, and K^b(Prj R) is the homotopy category of bounded complexes of projective R-modules. This result is set in the wider context of a theory for A^s(R) and B^s(R), the symmetric Bass category which is defined dually.

Jørgensen, Peter; Kato, Kiriko

2011-03-01

122

Quasi3D modeling, design, and analysis of symmetric on-chip inductors in silicon-on-sapphire technology  

Microsoft Academic Search

A design and analysis of symmetric on-chip planar inductors are presented based in 0.5 mum silicon-on-sapphire CMOS process of Peregrine Semiconductor. Compared to conventional CMOS processes, an insulating thick sapphire (Al2O3) substrate enables higher quality factor inductors due to low energy loss in the substrate. In addition, symmetric cross-coupled configuration of identical asymmetric inductors of thick top metalization minimizes the

Wan-Chul Kong; Said F. Al-Sarawi; Cheng-Chew Lim; Louis Wong

2004-01-01

123

Top-ophilia  

SciTech Connect

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.

Quigg, Chris; /Fermilab

2008-01-01

124

Multiple Rankine topping cycles  

SciTech Connect

The efficiency of a Rankine cycle is primarily determined by the temperatures of heat addition and rejection. However, no working fluid has been identified which will operate in a Rankine cycle over an extremely wide temperature range. Multiple Rankine topping cycles offer a technique for achieving high thermal efficiencies in power plants by allowing the use of several working fluids. This paper gives a history of Rankine topping cycles, presents an analysis for the calculation of the overall efficiency of a three-module multiple Rankine cycle, and presents results from a case study for a sodium-mercury-water cycle.

McWhirter, J.D. [Argonne National Lab., Idaho Falls, ID (United States). Engineering Div.]|[Idaho State Univ., Pocatello, ID (United States). Coll. of Engineering

1995-07-01

125

Marvelous Molecules  

NSDL National Science Digital Library

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.

1969-12-31

126

Adhesion molecules  

PubMed Central

Adhesion molecules are known to -be important components of an active T-cell mediated immune response. Signals generated at a site of inflammation cause circulating T cells to respond by rolling, arrest and then transmigration through the endothelium, all of which are mediated by adhesion molecules. Consequently, strategies have been developed to treat immune disorders with specific antibodies that block the interaction of adhesion molecules. However, the therapeutic effects of such remedies are not always achieved. Our recent investigations have revealed that intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) work together with chemokines to induce immunosuppression mediated by Mesenchymal stem cells (MSCs), thus demonstrating the dual role of adhesion molecules in immune responses. Since MSCs represent an important component of the stromal cells in an inflammatory microenvironment, our findings provide novel information for understanding the regulation of immune responses and for designing new strategies to treat immune disorders.

Ren, Guangwen; Roberts, Arthur I

2011-01-01

127

Top quark production at CDF  

SciTech Connect

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.

Moed, Shulamit; /Harvard U.

2010-01-01

128

Top Quark Production at CDF  

SciTech Connect

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 tt-bar 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.

Moed, Shulamit [Harvard University, Laboratory for Particle Physics and Cosmology, 18 Hammond St., Cambridge, MA, 02138 (United States)

2010-02-10

129

Modeling Symmetric Macromolecular Structures in Rosetta3  

PubMed Central

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.

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

2011-01-01

130

Stop reconstruction with tagged tops  

NASA Astrophysics Data System (ADS)

At the LHC combinatorics make it unlikely that we will be able to observe stop pair production with a decay to a semi-leptonic top pair and missing energy for generic supersymmetric mass spectra. Using a Standard-Model top tagger on fully hadronic top decays we can not only extract the stop signal but also measure the top momentum. To illustrate the promise of tagging tops with moderate boost we include a detailed discussion of our HEPTopTagger algorithm.

Plehn, Tilman; Spannowsky, Michael; Takeuchi, Michihisa; Zerwas, Dirk

2010-10-01

131

Top 100 Degree Producers.  

ERIC Educational Resources Information Center

|Provides data on bachelor's degrees awarded to minority students in 1999-2000. Tables include total minority degrees and degrees awarded to African Americans, American Indians, Asian Americans, and Hispanics by type of school (uses Carnegie classification). Another table presents top disciplines by race/ethnicity. (EV)|

Black Issues in Higher Education, 2001

2001-01-01

132

The Optics Project (TOP)  

Microsoft Academic Search

The Optics Project (TOP) is a multidisciplinary effort whose goal is to develop an interactive computer graphics system which will help upper level undergraduate students learn optics. The main objective of the project is to design a system in which the user (be it a professor in a classroom or a student outside of class) can call up the phenomenon

John T. Foley

1997-01-01

133

Spinning Tops (median)  

NSDL National Science Digital Library

Students measure distances using standard and non-standard units and record their measurement in various tables. Then they are asked to use descriptive statistics to report the results. During a top-spinning contest, students measure the distance along a curve using indirect measurement. They record the data for their group in a chart and compute their individual median and the group median.

Mathematics, Illuminations N.

2010-05-20

134

Potassium vapor topping cycle  

Microsoft Academic Search

The potassium vapor topping cycle is a concept for increasing the efficiency of the Rankine vapor cycle by raising the peak temperature by employing a potassium vapor cycle with a turbine inlet temperature of 1500 to 1600 F (815 to 870 C) in which the waste heat rejected from the condensing potassium vapor is transferred to boiling water and steam

R. S. Holcomb

1978-01-01

135

Ten Top Tech Trends  

ERIC Educational Resources Information Center

|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…

McLester, Susan

2008-01-01

136

Top Hispanic Degree Producers  

ERIC Educational Resources Information Center

|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…

Diverse: Issues in Higher Education, 2012

2012-01-01

137

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.

138

Interstellar molecules  

NASA Astrophysics Data System (ADS)

Complex molecules cycling from circumstellar envelopes through various phases of interstellar matter in the Milky Way are considered. Approximately 65 of the interstellar species detected so far are considered to be organic molecules. By interpreting molecular signatures, it is possible to determine the chemical composition, temperature, mass, internal motions, and evolutionary fate of a dark interstellar cloud.

Verschuur, Gerrit L.

1992-04-01

139

Demixing in symmetric supersolid mixtures  

NASA Astrophysics Data System (ADS)

The droplet crystal phase of a symmetric binary mixture of soft-core bosons is studied by computer simulation. At high temperature each droplet comprises on average equal numbers of particles of either component, but the two components demix below the supersolid transition temperature, i.e., droplets mostly consist of particles of one component. Clustering of droplets of the same component is also observed. Demixing is driven by quantum tunneling of particles across droplets over the system and does not take place in an insulating crystal. This effect provides an unambiguous experimental signature of supersolidity.

Jain, Piyush; Moroni, Saverio; Boninsegni, Massimo; Pollet, Lode

2013-09-01

140

PT-symmetric optical lattices  

SciTech Connect

The basic properties of Floquet-Bloch (FB) modes in parity-time (PT)-symmetric optical lattices are examined in detail. Due to the parity-time symmetry of such complex periodic potentials, the corresponding FB modes are skewed (nonorthogonal) and nonreciprocal. The conjugate pairs of these FB modes are obtained by reflecting both the spatial coordinate and the Bloch momentum number itself. The orthogonality conditions are analytically derived for a single cell, for both a finite and an infinite lattice. Some of the peculiarities associated with the diffraction dynamics in PT lattices such as nonreciprocity, power oscillations, and phase dislocations, are also examined.

Makris, Konstantinos G.; El-Ganainy, Ramy; Christodoulides, Demetrios N.; Musslimani, Z. H. [College of Optics/CREOL, University of Central Florida, Orlando, Florida 32816 (United States); Department of Mathematics, Florida State University Tallahassee, Florida 32306-4510 (United States)

2010-06-15

141

Conformally flat spherically symmetric spacetimes  

NASA Astrophysics Data System (ADS)

We deduce a simple expression for the Kretschmann curvature scalar of a conformally flat spacetime with a perfect fluid. Conformally flat, static, spherically symmetric spacetimes are investigated in various coordinate systems. The equation for a vanishing Weyl tensor and Einstein's field equations are integrated in curvature coordinates. We find conformally flat generalizations of the de Sitter spacetime and give new analyses of the internal Schwarzschild spacetime and texture-dominated spacetimes. The spacetimes are described in curvature coordinates, isotropic coordinates and in conformally flat spacetime coordinates.

Grøn, Øyvind; Johannesen, Steinar

2013-08-01

142

Paradigm shift in gene-finding method: From bench-top approach to desk-top approach (review).  

PubMed

Gene-finding methods are classified into homology-based bench-top approach (degenerate cDNA-PCR and cDNA selection), ab initio bench-top approach (cDNA subtraction, two-hybrid system, and exon trapping), homology-based desk-top approach (BLAST search), ab initio desk-top approach (Fgenesh and GENSCAN programs), and hybrid desk-top approach (GenomeScan program). cDNA-library screening, cDNA-PCR, and RACE are used to isolate cDNAs for complete coding sequences. Because WNT signaling molecules are potent targets for oncology, regenerative medicine, and other fields of medical science, we have cloned and characterized many human genes encoding WNT signaling molecules, including 13 out of 19 human WNT genes, and 9 out of 10 human FZD genes. We used degenerate cDNA-PCR and cDNA-library screening in the 20th century, while we use BLAST program and cDNA-PCR in the 21st century. The interval between gene-finding and manuscript-publication in my laboratory was 17.2+/-7.5 (mean +/- SD) months in the 20th century (n=13), 11.5+/-7.8 months in 2001 (n=19), and 5.5+/-1.6 months in 2002 (n=13). The interval using desk-top gene-finding approach (7.2+/-2.6 months, n=30) was significantly shorter than that using bench-top approach (19.8+/-8.0 months, n=15) (p=0.003). Gene-finding has been significantly accelerated due to paradigm shift from bench-top approach to desk-top approach. Dramatic increase of information about human genome, transcriptome and proteome accompanied by improvements of genomics, proteonics and bioinformatics technologies will accelerate paradigm shift from bench-top science to desk-top science. PMID:12429991

Katoh, Masaru

2002-12-01

143

22. Top Lateral Bracing & Top Chord, Vertical Tension Member ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

22. Top Lateral Bracing & Top Chord, Vertical Tension Member 6, end Vertical Compression Members 5 & 4; South Swing Span; looking N. - Pacific Shortline Bridge, U.S. Route 20,spanning Missouri River, Sioux City, Woodbury County, IA

144

Handling ER-top  

Microsoft Academic Search

\\u000a It is critical to manage uncertain data streams nowadays because data uncertainty widely exists in many applications, such\\u000a as Web and sensor networks. The goal of this paper is to handle top-k query on uncertain data streams. Since the volume of a data stream is unbounded whereas the memory resource is limited, it\\u000a is challenging to devise one-pass solutions that

Cheqing Jin; Ming Gao; Aoying Zhou

2011-01-01

145

Interstellar Molecules  

ERIC Educational Resources Information Center

|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)|

Solomon, Philip M.

1973-01-01

146

Probabilistic cloning of three symmetric states  

SciTech Connect

We study the probabilistic cloning of three symmetric states. These states are defined by a single complex quantity, the inner product among them. We show that three different probabilistic cloning machines are necessary to optimally clone all possible families of three symmetric states. We also show that the optimal cloning probability of generating M copies out of one original can be cast as the quotient between the success probability of unambiguously discriminating one and M copies of symmetric states.

Jimenez, O. [Center for Optics and Photonics, Departamento de Fisica, Universidad de Concepcion, Casilla 4016, Concepcion (Chile); Departamento de Fisica, Facultad de Ciencias Basicas, Universidad de Antofagasta, Casilla 170, Antofagasta (Chile); Bergou, J. [Department of Physics, Hunter College, City University of New York, 695 Park Avenue, New York, New York 10021 (United States); Delgado, A. [Center for Optics and Photonics, Departamento de Fisica, Universidad de Concepcion, Casilla 4016, Concepcion (Chile); Departamento de Fisica, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile)

2010-12-15

147

Adhesion molecules  

Microsoft Academic Search

Adhesion molecules are cell membrane receptors that mediate cell-to-cell and cell-to-matrix communication in macroorganisms. Because the receptors and ligands involved are non-diffusible, adhesion molecules are capable of organ, tissue and cell specific regulation under physiological and pathophysiological conditions. Consequently, this local (positional) regulatory system has the ability to alter\\/modify\\/tune systemic regulatory signals and generate signals locally in order to match

Istvan Berczi; Andor Szentivanyi

2003-01-01

148

Enumerating molecules.  

SciTech Connect

This report is a comprehensive review of the field of molecular enumeration from early isomer counting theories to evolutionary algorithms that design molecules in silico. The core of the review is a detail account on how molecules are counted, enumerated, and sampled. The practical applications of molecular enumeration are also reviewed for chemical information, structure elucidation, molecular design, and combinatorial library design purposes. This review is to appear as a chapter in Reviews in Computational Chemistry volume 21 edited by Kenny B. Lipkowitz.

Visco, Donald Patrick, Jr. (, . Tennessee Technological University, Cookeville, TN); Faulon, Jean-Loup Michel; Roe, Diana C.

2004-04-01

149

Symmetrical mixtures in external fields.  

PubMed

We have studied the behavior of symmetrical binary mixtures of Lennard-Jones particles in contact with strongly adsorbing walls using Monte Carlo simulation methods in the grand canonical and semi-grand canonical ensembles. Two types of the surface potential have been applied. The first depends on the distance from the surface only, while the second involves periodic modulations in the directions parallel to the wall. In the latter case, it has been assumed that the solid substrate is a fcc crystal with the surface being the (100) face. We have considered the systems in which the surface potential is strong enough to induce the layer-by-layer adsorption at low temperatures and discussed the interplay between the demixing transition and the structure of thin films for several systems characterized by different parameters describing the interactions in the system. PMID:23822318

Materniak, S; Patrykiejew, A

2013-07-01

150

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...

151

Top quark physics: Future measurements.  

National Technical Information Service (NTIS)

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 ...

R. Frey S. Vejcik E. L. Berger

1997-01-01

152

Top physics results at CDF  

SciTech Connect

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.

Vickey, Trevor; /Illinois U., Urbana

2005-05-01

153

Applying Symmetric Enumeration Method to One-Dimensional Assembly of Rotatable Tiles  

Microsoft Academic Search

Motivated by the increasing importance of the analysis of a complicated reaction system where molecules are interacting in\\u000a various ways to produce a huge number of compounds of molecules, the author’s previous work proposed a new approach, called\\u000a Symmetric Enumeration Method (SEM), to the efficient analysis of such reaction systems. The proposed theory provided a general\\u000a method for the efficient

Satoshi Kobayashi

2009-01-01

154

Top 50 Financial Websites  

NSDL National Science Digital Library

In order to help their users navigate around the World Wide Web, Money.com has ranked the top 50 financial sites found on the Internet. A wide list of types of sites is posted in a column on the left side of the screen, including the broad categories of Portals, Investing, and Saving and Spending. Two or three of the best sites are pithily described, and visitors are encouraged to vote for their favorite financial sites. This superlative list will help users quickly find the best financial sites for their needs.

155

Symmetric and near-symmetric objects in ductile shear zones- examples from Higher Himalaya, Bhagirathi section, India  

NASA Astrophysics Data System (ADS)

Ductile shear zones contain numerous asymmetric fabrics/structures/clasts/ objects of three overall geometries viz. sigmoidal, lenticular and parallelogram-shaped (Mukherjee, 2011). These indicate the shear sense of the rock, and have been reviewed from time to time by other authors and myself. By contrast, there has been no concise study or review of symmetric and near symmetric objects within ductile shear zones. This work studies morphologies of such symmetric objects from the Bhagirathi river section in the Higher Himalaya (HH), India. The HH in this section began top-to~SW compressional ductile shear at ~ 25 Ma. This was followed by intervals of extrusion by channel flow alternating with critical taper spreading from~ 18 Ma onwards. During its two pulses/phases of channel flow, two sub-zones of extensional ductile top-to~NE shear developed (Mukherjee, in press). Mesoscopic near symmetric objects in the HH are of the following types. (A) Isolated objects- most often lenticular/elliptical, but rarely sub-circular, rectangular or rhombic. (B) Gently curved quartz veins. (C) Warped NE dipping main foliations. (D) Nearly uniformly thin quartzofeldspathic foliations that bulge locally into sub-circular or sub-elliptical shapes. Most of the fractures inside clasts are irregular and their geometries do not conclusively indicate any shear sense. In general these fractures are confined to within the (harder?) clasts, very gently curved, sub-parallel to each other, and are at high angle with ~ NE dipping main foliations defined within mylonitized host rocks. This probably indicates (local?) brittle-ductile extension parallel to the main foliation. Notice that (a) one common explanation for the evolution of S-fabrics is that they rotate towards parallelism with the C-planes as the intensity of shear increases; and (b) lenticular clasts in mylonitized gneiss have classically been called 'augens'. In both these cases, a low-angle S-fabric and 'augen' may not indicate a clear shear sense. References Mukherjee S. (2011) Mineral Fish: their morphological classification, usefulness as shear sense indicators and genesis. International Journal of Earth Sciences 100, 1303-1314. Mukherjee S (in press) Higher Himalaya in the Bhagirathi section (NW Himalaya, India)- its structures, backthrusts, and extrusion mechanism by both channel flow and critical taper mechanisms. International Journal of Earth Sciences.

Mukherjee, Soumyajit

2013-04-01

156

Top quark physics at CDF  

SciTech Connect

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.

Potamianos, Karolos

2011-12-01

157

Commercial Cooking Equipment Improvement. Volume III: Open Top, Hot Top and Fry Top Ranges.  

National Technical Information Service (NTIS)

This report describes the efforts of a project aimed at improving the thermal efficiency of gas-fired commercial cooking equipment, specifically heavy duty and restaurant range open top sections and heavy duty hot top and fry top sections. The work was to...

R. L. Himmel

1982-01-01

158

Top quark mass measurements  

SciTech Connect

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}.

L. Cerrito

2004-07-16

159

Top quark properties at CDF  

SciTech Connect

During the last decade after discovery of top quark, top quark has been inclusively studied. By now, the mass of the top quark has been measured to be 173.1 {+-} 1.3 GeV/c{sup 2} which is the most precisely measured quark mass and t{bar t} pair production cross section has been measured as less than 10% of uncertainties. However, many of another top quark property have not yet been well explored due to the limited statistics. In the ongoing data taking at Fermilab's Tevatron proton-antiproton collider with Collider Detector at Fermilab (CDF), an increasing of integrated luminosity can make us to measure the property and also discover the unexpected phenomena from top sector. We describes a few of the CDF's progress of top quark property measurements. We present the top property measurements in the CDF. Most of measurements utilize close to the integrated luminosity of 3 fb{sup -1}.

Lee, Hyun Su; Collaboration, for the CDF

2009-10-01

160

Symmetrized plane waves: 3. nonsymmorphic space groups  

NASA Astrophysics Data System (ADS)

A procedure for systematically constructing symmetrized plane waves, or more generally, arbitrary Bloch-functions, is extended to the case of nonsymmorphic space groups. The technical part to compute those transformations coefficients that are necessary to determine symmetrized plane waves or Bloch-functions, is transferred to a correspondingly tailored software package.

Dirl, R.; Payer, K.; Davies, B. L.

1996-10-01

161

Angular Motion of Spinning Almost Symmetric Missiles.  

National Technical Information Service (NTIS)

An almost symmetric missile is a missile whose zero-spin pitch and yaw frequencies are 'nearly' equal. The angular motion of a spinning almost symmetric missile can be described by five rotating modal vectors. Two of these vectors vanish when the frequenc...

C. H. Murphy

1978-01-01

162

On Symmetric irreducible tensors in d -dimensions  

Microsoft Academic Search

This paper establishes the notion of symmetric irreducible tensors with arbitrary dimensions d̀. These tensors are generalisations of a symmetric traceless, second order tensor and their significance stems from their close connection to spherical harmonics. We introduce the general concepts and derive some fundamental relations with respect to these tensors. Special considerations are given to proofs, because those are hard

H. Ehrentraut; W. Muschik

1998-01-01

163

On the Symmetric Space ?-MODEL Kinematics  

NASA Astrophysics Data System (ADS)

The solvable Lie algebra parametrization of the symmetric spaces is discussed. Based on the solvable Lie algebra gauge two equivalent formulations of the symmetric space sigma model are studied. Their correspondence is established by inspecting the normalization conditions and deriving the field transformation laws.

Yilmaz, Nejat T.

164

Top-Higgs and top-pion phenomenology in the top triangle moose model  

SciTech Connect

We discuss the deconstructed version of a topcolor-assisted technicolor model wherein the mechanism of top quark mass generation is separated from the rest of electroweak symmetry breaking. The minimal deconstructed version of this scenario is a ''triangle moose'' model, where the top quark gets its mass from coupling to a top-Higgs field, while the gauge boson masses are generated from a Higgsless sector. The spectrum of the model includes scalar (top-Higgs) and pseudoscalar (top-pion) states. In this paper, we study the properties of these particles, discuss their production mechanisms and decay modes, and suggest how best to search for them at the LHC.

Chivukula, R. Sekhar; Simmons, Elizabeth H.; Coleppa, Baradhwaj; Logan, Heather E.; Martin, Adam [Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); Ottawa-Carleton Institute for Physics, Carleton University, Ottawa, Ontario K1S 5B6 (Canada); Theoretical Physics Department, Fermilab, Batavia, Illinois 60510 (United States)

2011-03-01

165

A maximally symmetric no-scale inflationary universe  

NASA Astrophysics Data System (ADS)

We present an inflationary model, based on maximally symmetric no-scale supergravity models, where the gravitino and inflation scale cosmological problems are solved simultaneously by means of a heavy - but weakly coupled to ordinary matter - gravitino. The gravitino mass is essentially given by the Hubble constant at the inflationary epoch, H?1012 GeV. The reheating temperature of the universe after inflation is TR?(1010-1011) GeV and so gravitinos are no longer regenerated. The grand unified theory suffers a rapid phase transition into the SU(3)×SU(2)×U(1) phase, during - or at the end of - inflation with dilution of magnetic monopoles. The dynamical determination of the electroweak scale predicts top quark masses between 40 and 50 GeV. Laboratoire Propre du Centre National de la Recherche Scientifique, associé à l'Ecole Normale Supérieure et à l'Université de Paris-Sud.

Kounnas, C.; Quiros, M.

1985-02-01

166

``Super''-dilatation symmetry of the top-Higgs system  

NASA Astrophysics Data System (ADS)

The top-Higgs system, consisting of top-quark (left-handed doublet and right-handed singlet) and Higgs boson kinetic terms, with gauge fields set to zero, has an exact (modulo total divergences) symmetry where both fermion and Higgs fields are shifted and mixed in a supersymmetric fashion. The full Higgs-Yukawa interaction and Higgs potential, including additional ˜1/?2 Nambu-Jona-Lasinio-like interactions, also has this symmetry to O(1/?4), up to null operators. Thus, the interaction Lagrangian can be viewed as a power series in O(1/?2). The symmetry involves the interplay of the Higgs quartic interaction with the Higgs-Yukawa interaction and implies the relationship ?=(1)/(2)gt2 between the top-Yukawa coupling gt and Higgs quartic coupling ? at a high energy scale ?? few TeV. We interpret this to be a new physics scale. The top quark is massless in the symmetric phase, satisfying the Nambu-Goldstone theorem. The fermionic shift part of the current is ?(1-H†H/v2), owing to the interplay of ? and gt, and vanishes in the broken phase. Hence, the Nambu-Goldstone theorem is trivially evaded in the broken phase and the top quark becomes heavy. We have mt=mh, subject to radiative corrections that can, in principle, pull the Higgs into concordance with experiment.

Hill, Christopher T.

2013-03-01

167

The Arabidopsis oligopeptidases TOP1 and TOP2 are salicylic acid targets that modulate SA-mediated signaling and the immune response.  

PubMed

Salicylic acid (SA) is a small phenolic molecule with hormonal properties, and is an essential component of the immune response. SA exerts its functions by interacting with protein targets; however, the specific cellular components modulated by SA and critical for immune signal transduction are largely unknown. To uncover cellular activities targeted by SA, we probed Arabidopsis protein microarrays with a functional analog of SA. We demonstrate that thimet oligopeptidases (TOPs) constitute a class of SA-binding enzymes. Biochemical evidence demonstrated that SA interacts with TOPs and inhibits their peptidase activities to various degrees both in vitro and in plant extracts. Functional characterization of mutants with altered TOP expression indicated that TOP1 and TOP2 mediate SA-dependent signaling and are necessary for the immune response to avirulent pathogens. Our results support a model whereby TOP1 and TOP2 act in separate pathways to modulate SA-mediated cellular processes. PMID:24004003

Moreau, Magali; Westlake, Timothy; Zampogna, Giulio; Popescu, George; Tian, Miaoying; Noutsos, Christos; Popescu, Sorina

2013-10-18

168

Hunting mixed top squark decays.  

PubMed

We point out that, in the irreducible natural supersymmetric spectrum, top squarks have comparable branching fractions to chargino-bottom and neutralino-top final states in the vast bulk of parameter space, provided only that both decay modes are kinematically accessible. The total top squark pair branching fractions into tt[over ¯]+MET (MET=missing transverse energy) can therefore be reduced to O(50%), whereas bb[over ¯]+X branching fractions are typically much smaller, O(10%), thus limiting the reach of traditional top squark searches. We propose a new top squark search targeting the asymmetric final state t[over ˜]t[over ˜]^{*}?t?^{0}b[over ¯]?^{-}+H.c., which can restore sensitivity to natural top squarks in the 7 and 8 TeV LHC runs. In addition, we present a new variable, topness, which efficiently suppresses the dominant top backgrounds to semileptonic top partner searches. We demonstrate the utility of topness in both our asymmetric search channel and traditional t[over ˜]t[over ˜]^{*}?tt[over ¯]+MET searches and show that it matches or outperforms existing variables. PMID:24093249

Graesser, Michael L; Shelton, Jessie

2013-09-18

169

Hunting Mixed Top Squark Decays  

NASA Astrophysics Data System (ADS)

We point out that, in the irreducible natural supersymmetric spectrum, top squarks have comparable branching fractions to chargino-bottom and neutralino-top final states in the vast bulk of parameter space, provided only that both decay modes are kinematically accessible. The total top squark pair branching fractions into tt¯+MET (MET=missingtransverseenergy) can therefore be reduced to O(50%), whereas bb¯+X branching fractions are typically much smaller, O(10%), thus limiting the reach of traditional top squark searches. We propose a new top squark search targeting the asymmetric final state t˜t˜*?t?0b¯?-+H.c., which can restore sensitivity to natural top squarks in the 7 and 8 TeV LHC runs. In addition, we present a new variable, topness, which efficiently suppresses the dominant top backgrounds to semileptonic top partner searches. We demonstrate the utility of topness in both our asymmetric search channel and traditional t˜t˜*?tt¯+MET searches and show that it matches or outperforms existing variables.

Graesser, Michael L.; Shelton, Jessie

2013-09-01

170

Heat conduction of symmetric lattices.  

PubMed

Heat conduction of symmetric Frenkel-Kontorova (FK) lattices with a coupling displacement was investigated. Through simplifying the model, we derived analytical expression of thermal current of the system in the overdamped case. By means of numerical calculations, the results indicate that: (i) As the coupling displacement d equals to zero, temperature oscillations of the heat baths linked with the lattices can control magnitude and direction of the thermal current; (ii) Whether there is a temperature bias or not, the thermal current oscillates periodically with d, whose amplitudes become greater and greater; (iii) As d is not equal to zero, the thermal current monotonically both increases and decreases with temperature oscillation amplitude of the heat baths, dependent on values of d; (iv) The coupling displacement also induces nonmonotonic behaviors of the thermal current vs spring constant of the lattice and coupling strength of the lattices; (v) These dynamical behaviors come from interaction of the coupling displacement with periodic potential of the FK lattices. Our results have the implication that the coupling displacement plays a crucial role in the control of heat current. PMID:23848662

Nie, Linru; Yu, Lilong; Zheng, Zhigang; Shu, Changzheng

2013-06-28

171

Top quark physics  

SciTech Connect

Most of the material presented in this report, comes from contributions to the parallel session PL20 of this conference. We summarise the experimental results of direct production of Top quarks, coming from the CDF and C0 Collaborations at Fermilab, and compare these results to what one expects within current theoretical understanding. Particular attention is given to new results such as all hadronic modes of t{bar t} decay. As far as the mass is concerned, a comparison is made with precision measurements of related quantities, coming from LEP and other experiments. An attempt is made to look at the medium-term future and understand which variables and with what accuracy one can measure them with increased integrated luminosity.

Menzione, A. [INFN Sezione di Pisa (Italy)

1995-10-01

172

A DNA primer associated with banana bunchy top virus  

Microsoft Academic Search

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

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

173

Top physics results from CDF  

SciTech Connect

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.

Gomez, Gervasio; /Cantabria Inst. of Phys.

2005-05-01

174

Photofragment angular momentum distributions in the molecular frame. II. Single state dissociation, multiple state interference, and nonaxial recoil in photodissociation of polyatomic molecules  

NASA Astrophysics Data System (ADS)

We present an aqk(s) polarization-parameter model to describe product angular momentum polarization from the one-photon photodissociation of polyatomic molecules in the molecular frame. We make the approximation that the final photofragment recoil direction is unique and described by the molecular frame polar coordinates (?,Ji), for which the axial recoil approximation is a special case (e.g., ?=0). This approximation allows the separation of geometrical and dynamical factors, in particular, the expression of the experimental sensitivities to each of the aqk(s) in terms of the molecular frame polar angles (?i,Ji) of the transition dipole moment ?i. This separation is applied to the linearly polarized photodissociation of polyatomic molecules (asymmetric, symmetric, and spherical top molecules are discussed) and to all dissociation mechanisms that satisfy our recoil approximation, including those with nonaxial recoil and multiple state interference, giving important insight into the geometrical properties of the photodissociation mechanism. For example, we demonstrate that the ratio of polarization parameters A0k(aniso)/A0k(iso)=? (where ? is the spatial anisotropy parameter) is an indication that the dynamics can be explained by a single dissociative state. We also show that for asymmetric top photodissociation, the sensitivity to the a1k(s) parameters, which can arise either from single-surface or multiple-surface interference mechanisms, is nonzero only for components of the transition dipole moments within the v-d plane of the recoil frame.

Rakitzis, T. Peter; Alexander, Andrew J.

2010-06-01

175

Top quark search at CDF  

SciTech Connect

The current status of the Top quark search at CDF is presented. A lower limit on the Top mass of 113 GeV has been established using the dilepton channel with the data collected during the 1988--1989 and 1992--1993 runs at {radical}s= 1.8 TeV. Prospects for Top quark discovery during the 1993--1994 run are also outlined.

Benlloch, J.M. [Massachusetts Inst. of Technology, Cambridge, MA (United States); CDF Collaboration

1993-11-01

176

Reverse top-k queries  

Microsoft Academic Search

Rank-aware query processing has 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, focusing primarily on efficient query processing. In this work, for the first time, we study top-k queries from the perspective of the product manufacturer.

Akrivi Vlachou; Christos Doulkeridis; Yannis Kotidis; Kjetil Nørvåg

2010-01-01

177

Moving Molecules!  

NSDL National Science Digital Library

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.

Twin Cities Public Television, Inc.

2008-01-01

178

Top-down mass spectrometry: recent developments, applications and perspectives.  

PubMed

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

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

2011-08-08

179

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

PubMed Central

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.

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

2012-01-01

180

Z' signals in polarised top-antitop final states  

NASA Astrophysics Data System (ADS)

We study the sensitivity of top-antitop samples produced at all energy stages of the Large Hadron Collider (LHC) to the nature of an underlying Z' boson, in presence of full tree level standard model (SM) background effects and relative interferences. We concentrate on differential mass spectra as well as both spatial and spin asymmetries thereby demonstrating that exploiting combinations of these observables will enable one to distinguish between sequential Z's and those pertaining to Left-Right symmetric models as well as E 6 inspired ones, assuming realistic final state reconstruction efficiencies and error estimates.

Basso, L.; Mimasu, K.; Moretti, S.

2012-09-01

181

Averaging in spherically symmetric cosmology  

SciTech Connect

The averaging problem in cosmology is of fundamental importance. When applied to study cosmological evolution, the theory of macroscopic gravity (MG) can be regarded as a long-distance modification of general relativity. In the MG approach to the averaging problem in cosmology, the Einstein field equations on cosmological scales are modified by appropriate gravitational correlation terms. We study the averaging problem within the class of spherically symmetric cosmological models. That is, we shall take the microscopic equations and effect the averaging procedure to determine the precise form of the correlation tensor in this case. In particular, by working in volume-preserving coordinates, we calculate the form of the correlation tensor under some reasonable assumptions on the form for the inhomogeneous gravitational field and matter distribution. We find that the correlation tensor in a Friedmann-Lemaitre-Robertson-Walker (FLRW) background must be of the form of a spatial curvature. Inhomogeneities and spatial averaging, through this spatial curvature correction term, can have a very significant dynamical effect on the dynamics of the Universe and cosmological observations; in particular, we discuss whether spatial averaging might lead to a more conservative explanation of the observed acceleration of the Universe (without the introduction of exotic dark matter fields). We also find that the correlation tensor for a non-FLRW background can be interpreted as the sum of a spatial curvature and an anisotropic fluid. This may lead to interesting effects of averaging on astrophysical scales. We also discuss the results of averaging an inhomogeneous Lemaitre-Tolman-Bondi solution as well as calculations of linear perturbations (that is, the backreaction) in an FLRW background, which support the main conclusions of the analysis.

Coley, A. A.; Pelavas, N. [Department of Mathematics and Statistics, Dalhousie University, Halifax, Nova Scotia (Canada)

2007-02-15

182

Rotational relaxation of symmetric tops CH3D and CD3H in some inert liquids  

Microsoft Academic Search

Infra-red spectra of CH3D and CD3H dissolved in liquid Ar, Kr, Xe, N2, O2 and CH4 or CF4 have been recorded. From the band shapes, rotational correlation functions, band moments and intermolecular mean square torques have been calculated. To describe the tumbling motion, involved in the parallel band profiles, we have computed the theoretical correlation functions in the m or

J. P. Marsault; F. Marsault-Herail; G. Levi

1973-01-01

183

Top coat or no top coat for immersion lithography?  

Microsoft Academic Search

Since the moment immersion lithography appeared in the roadmaps of IC manufacturers, the question whether to use top coats has become one of the important topics for discussions. The top coats used in immersion lithography have proved to serve as good protectors from leaching of the resist components (PAGs, bases) into the water. However their application complicates the process and

N. Stepanenko; Hyun-Woo Kim; S. Kishimura; D. Van Den Heuvel; N. Vandenbroeck; M. Kocsis; P. Foubert; M. Maenhoudt; M. Ercken; F. Van Roey; R. Gronheid; I. Pollentier; D. Vangoidsenhoven; C. Delvaux; C. Baerts; S. O'Brien; W. Fyen; G. Wells

2006-01-01

184

Dynamics of charged plane symmetric gravitational collapse  

NASA Astrophysics Data System (ADS)

In this paper, we study dynamics of the charged plane symmetric gravitational collapse. For this purpose, we discuss non-adiabatic flow of a viscous fluid and deduce the results for adiabatic case. The Einstein and Maxwell field equations are formulated for general plane symmetric spacetime in the interior. Junction conditions between the interior and exterior regions are derived. For the non-adiabatic case, the exterior is taken as plane symmetric charged Vaidya spacetime while for the adiabatic case, it is described charged plane symmetric spacetime. Using Misner and Sharp formalism, we obtain dynamical equations to investigate the effects of different forces over the rate of collapse. In non-adiabatic case, a dynamical equation is joined with transport equation of heat flux. Finally, a relation between the Weyl tensor and energy density is found.

Sharif, M.; Siddiqa, Aisha

2011-01-01

185

Gaussian Multiplicative Chaos for Symmetric Isotropic Matrices  

NASA Astrophysics Data System (ADS)

Motivated by isotropic fully developed turbulence, we define a theory of symmetric matrix valued isotropic Gaussian multiplicative chaos. Our construction extends the scalar theory developed by J.P. Kahane in 1985.

Chevillard, Laurent; Rhodes, Rémi; Vargas, Vincent

2013-02-01

186

Multifrontal Parallel Distributed Symmetric and Unsymmetric Solvers.  

National Technical Information Service (NTIS)

The authors consider the solution of both symmetric of sparse linear equations. A new parallel distributed memory multifrontal approach is described. To handle numerical pivoting efficiently, a parallel asynchronous algorithm with dynamic scheduling of th...

P. R. Amestoy I. S. Duff J. Y. L'Excellent

1998-01-01

187

Nonlocality and entanglement for symmetric states  

NASA Astrophysics Data System (ADS)

In this paper, building on some recent progress combined with numerical techniques, we shed some light on how the nonlocality of symmetric states is related to their entanglement properties and on their potential usefulness in quantum information processing. We use semidefinite programming techniques to devise a device-independent classification of three 4-qubit states into two classes inequivalent under local unitaries and permutation of systems. We study nonlocal properties when the number of parties grows large for two important classes of symmetric states: W states and GHZ states, showing that they behave differently under the inequalities we consider. We also discuss the monogamy arising from the nonlocal correlations of symmetric states. We show that although monogamy in a strict sense is not guaranteed for all symmetric states, strict monogamy is achievable for all Dicke states when the number of parties goes to infinity.

Wang, Zizhu; Markham, Damian

2013-01-01

188

PT-Symmetric Quantum Field Theory  

SciTech Connect

In 1998 it was discovered that the requirement that a Hamiltonian be Dirac Hermitian (H = H{sup {dagger}}) can be weakened and generalized to the requirement that a Hamiltonian be PT symmetric ([H,PT] = 0); that is, invariant under combined space reflection and time reversal. Weakening the constraint of Hermiticity allows one to consider new kinds of physically acceptable Hamiltonians and, in effect, it amounts to extending quantum mechanics from the real (Hermitian) domain into the complex domain. Much work has been done on the analysis of various PT-symmetric quantum-mechanical models. However, only very little analysis has been done on PT-symmetric quantum-field-theoretic models. Here, we describe some of what has been done in the context of PT-symmetric quantum field theory and describe some possible fundamental applications.

Bender, Carl M. [Physics Department, Washington University, St. Louis, MO 63130 (United States)

2011-09-22

189

Postpartum Peripheral Symmetrical Gangrene: A Case Report  

PubMed Central

Background Symmetrical peripheral gangrene is usually associated with underlying medical problems and it is seldom seen in pregnancy. Sepsis though common in a setting of delivery by unskilled midwife is rarely accompanied by symmetrical gangrene. Case Presentation We report a case of symmetrical peripheral gangrene which occurred in the winter, triggered possibly by sepsis and a single dose of ergot. A high index of suspicion, early diagnosis and intervention with appropriate measures will result in favorable outcome in such cases. Conclusion Although postpartum period is of high risk for sepsis and use of ergot alkaloids is common in labor but occurrence of peripheral symmetrical gangrene is rare. A high index of suspicion for the diagnosis and timely intervention will prevent irreparable damage and loss of limb.

Sharma, Lipi; Mehta, Sumita; Rajaram, Shalini; Aggarwal, Rachna; Gupta, Sanjay; Goel, Neerja

2012-01-01

190

PT-Symmetric Quantum Field Theory  

NASA Astrophysics Data System (ADS)

In 1998 it was discovered that the requirement that a Hamiltonian be Dirac Hermitian (H = H†) can be weakened and generalized to the requirement that a Hamiltonian be PT symmetric ([H,PT] = 0) that is, invariant under combined space reflection and time reversal. Weakening the constraint of Hermiticity allows one to consider new kinds of physically acceptable Hamiltonians and, in effect, it amounts to extending quantum mechanics from the real (Hermitian) domain into the complex domain. Much work has been done on the analysis of various PT-symmetric quantum-mechanical models. However, only very little analysis has been done on PT-symmetric quantum-field-theoretic models. Here, we describe some of what has been done in the context of PT-symmetric quantum field theory and describe some possible fundamental applications.

Bender, Carl M.

2011-09-01

191

Symmetric Space ?-MODEL Dynamics:. Current Formalism  

NASA Astrophysics Data System (ADS)

After explicitly constructing the symmetric space sigma model Lagrangian in terms of the coset scalars of the solvable Lie algebra gauge in the current formalism, we derive the field equations of the theory.

Yilmaz, Nejat T.

192

Symmetric-key cryptosystem with DNA technology  

Microsoft Academic Search

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

Mingxin Lu; Xuejia Lai; Guozhen Xiao; Lei Qin

2007-01-01

193

Symmetric informationally complete measurements of arbitrary rank  

Microsoft Academic Search

There has been much interest in so-called SIC-POVMs, i.e., rank 1 symmetric informationally complete positive operator valued\\u000a measures. In this paper we discuss the larger class of POVMs that are symmetric and informationally complete, but not necessarily\\u000a rank 1. This class of POVMs is of some independent interest. In particular it includes a POVM that is closely related to the

D. M. Appleby

2007-01-01

194

Walking molecules.  

PubMed

Movement is intrinsic to life. Biologists have established that most forms of directed nanoscopic, microscopic and, ultimately, macroscopic movements are powered by molecular motors from the dynein, myosin and kinesin superfamilies. These motor proteins literally walk, step by step, along polymeric filaments, carrying out essential tasks such as organelle transport. In the last few years biological molecular walkers have inspired the development of artificial systems that mimic aspects of their dynamics. Several DNA-based molecular walkers have been synthesised and shown to walk directionally along a track upon sequential addition of appropriate chemical fuels. In other studies, autonomous operation--i.e. DNA-walker migration that continues as long as a complex DNA fuel is present--has been demonstrated and sophisticated tasks performed, such as moving gold nanoparticles from place-to-place and assistance in sequential chemical synthesis. Small-molecule systems, an order of magnitude smaller in each dimension and 1000× smaller in molecular weight than biological motor proteins or the walker systems constructed from DNA, have also been designed and operated such that molecular fragments can be progressively transported directionally along short molecular tracks. The small-molecule systems can be powered by light or chemical fuels. In this critical review the biological motor proteins from the kinesin, myosin and dynein families are analysed as systems from which the designers of synthetic systems can learn, ratchet concepts for transporting Brownian substrates are discussed as the mechanisms by which molecular motors need to operate, and the progress made with synthetic DNA and small-molecule walker systems reviewed (142 references). PMID:21416072

von Delius, Max; Leigh, David A

2011-03-17

195

Learning at the Top. Symposium.  

ERIC Educational Resources Information Center

|This document contains three papers from a symposium on learning at the top that was conducted as part of a conference on human resource development (HRD). "Learning at the Top: An Investigation of Nonprofit CEOs' (Chief Executive Officers') Learning Experiences" (John J. Sherlock) reports on a study that used Mezirow's theory of adult learning…

2002

196

Spherical Top Data System (STDS) software for the simulation of spherical top spectra.  

NASA Astrophysics Data System (ADS)

The Spherical Top Data System (STDS) software package for the simulation of spherical top spectra is presented. It consists of a single UNIX script with self-explanatory arguments allowing the non-expert user to calculate spectra from the results of the high resolution analyses performed over the recent decades on this type of molecules. More than one hundred parameter files are presently available including various band systems of 16 molecular species (among which methane is the most documented) and various types of calculations: rovibrational energy levels, i.r. absorption, Raman scattering and Stark coefficients. The basic instructions to get, install and execute STDS are explained. The current status of the STDS content is described.

Wenger, C.; Champion, J. P.

1998-05-01

197

Top Quark Properties from Top Pair Events and Decays  

SciTech Connect

Over a decade since the discovery of the top quark we are still trying to unravel mysteries of the heaviest observed particle and learn more about its nature. The continuously accumulating statistics of CDF and DO data provide the means for measuring top quark properties with ever greater precision and the opportunity to search for signs of new physics that could be manifested through subtle deviations from the standard model in the production and decays of top quarks. In the following we present a slice of the rich program in top quark physics at the Fermilab Tevatron: measurements of the properties of top quark decays and searches for unusual phenomena in events with pair produced tops. In particular, we discuss the most recent and precise CDF and DO measurements of the transverse polarization of W bosons from top decays, branching ratios and searches for flavor-changing neutral current decays, decays into charged Higgs and invisible decays. These analyses correspond to integrated luminosities ranging from 0.9 to 2.7 fb{sup -1}.

Ivanov, A.; /UC, Davis

2008-11-01

198

Status of the top quark: Top production cross section and top properties  

SciTech Connect

This report describes the latest cross section and property measurements associated with the top quark at the Tevatron Run II. The largest data sample used is 760 pb{sup -1} of integrated luminosity. Due to its large mass, the top quark might be involved in the process of electroweak symmetry breaking, making it a useful probe for signs of new physics.

Boisvert, V.; /Rochester U.

2006-08-01

199

Oxygen-Induced Symmetrization and Structural Coherency in Fe/MgO/Fe(001) Magnetic Tunnel Junctions  

SciTech Connect

We present x-ray diffraction experiments and multiple-scattering calculations on the structure and transport properties of a Fe/MgO/Fe(001) magnetic tunnel junction (MTJ). Coherent growth of the top Fe electrode on the MgO spacer is observed only for Fe deposition in ambient oxygen atmosphere leading to a coherent and symmetric MTJ structure characterized by FeO layers at both Fe/MgO interfaces. This goes in parallel with calculations indicating large positive tunnel magnetoresistance (TMR) values in such symmetric junctions. The results have important implications for achieving giant TMR values.

Tusche, C.; Meyerheim, H.L.; Ernst, A.; Henk, J.; Bruno, P.; Kirschner, J. [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Germany); Jedrecy, N. [Institut des NanoSciences de Paris, Universites Paris 6 et 7, et CNRS-UMR 7588, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Renaud, G. [CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble (France)

2005-10-21

200

Microwave spectroscopic detection of a transient phosphorus-bearing molecule, H3PO  

NASA Astrophysics Data System (ADS)

The microwave spectrum of the transient phosphine oxide, H3PO, was detected in the gas phase for the first time using a source-modulated spectrometer. The H3PO molecule was generated in a free space cell by a dc glow discharge of a mixture of PH3, CO2, and H2 gases and the corresponding spectral lines for each rotational transition of H3PO formed a pattern clearly indicative of a symmetric top molecule. Isotopomers of H3PO, i.e., H3P18O and D3PO were also produced; H3P18O in the same fashion as for H3PO, and D3PO, in a mixture of D2 and CO2 gases passing over red phosphorus grains. In total, 54 spectral lines of H3PO, 55 lines of H3P18O, and 61 lines of D3PO were measured for the fine structure of rotational transitions, J=2-1 to 12-11. The rotational constant, B0, and centrifugal constants, DJ, DJK, and HKJ were ascertained by a least squares analysis of the measured frequencies for each of the species. Using the rotational constants of the three isotopic species, the following r0 structure was determined: r0 (PO)=1.4763 Å, r0(PH)=1.4406 Å, and ?HPO=114.26°. The value of each structural parameter deviates significantly from the most recent results predicted by ab initio calculations.

Ahmad, Imtiaz K.; Ozeki, Hiroyuki; Saito, Shuji

1999-01-01

201

Top quark property at Tevatron  

NASA Astrophysics Data System (ADS)

The top quark, the heaviest known elementary particle, remains by far the most interesting particle to test standard model as well as search new physics beyond standard model because of its large mass and unique properties. Having data collected about 10 fb-1 of integrated luminosity of pp? collisions, both experiments have been studied the top quark in all the possible directions. In this report, we present the recent measurements of the top quark properties from Tevatron including the mass, width, and W boson helicity using ?tt? signature.

Lee, Hyun Su

2013-05-01

202

Training Top 10 Hall of Fame  

ERIC Educational Resources Information Center

|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

Training, 2012

2012-01-01

203

Novel symmetrical ureas as modulators of protein arginine methyl transferases.  

PubMed

Methylation of histone arginine residues is an epigenetic mark related to gene expression that is implicated in a variety of biological processes and can be reversed by small-molecule modulators of protein arginine methyltransferases (PRMTs). A series of symmetrical ureas, designed as analogues of the known PRMT1 inhibitor AMI-1 have been synthesized using Pd-catalyzed Ar-N amide bond formation processes or carbonylation reactions as key steps. Their inhibitory profile has been characterized. The enzymatic assays showed a weak effect on PRMT1 and PRMT5 activity for most of the compounds. The acyclic urea that exhibited the strongest effect on the inhibition of the PRMT1 activity also showed the greatest effect on the expression of some androgen receptor target genes (TMPRSS2 and FKBP5), which may be related with its enzymatic activity. Surprisingly, AMI-1 behaved as an activator of PRMT5 activity, a result not reported so far. PMID:23395110

Fontán, Noelia; García-Domínguez, Patricia; Álvarez, Rosana; de Lera, Ángel R

2013-01-22

204

Top 10 Products of 2011  

ERIC Educational Resources Information Center

|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…

American School & University, 2011

2011-01-01

205

Mind molecules.  

PubMed

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

Snyder, Solomon H

2011-05-04

206

Mind Molecules  

PubMed Central

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.

Snyder, Solomon H.

2011-01-01

207

Molecular theory for self assembling mixtures of patchy colloids and colloids with spherically symmetric attractions: The single patch case  

NASA Astrophysics Data System (ADS)

In this work we develop a new theory to model self assembling mixtures of single patch colloids and colloids with spherically symmetric attractions. In the development of the theory we restrict the interactions such that there are short ranged attractions between patchy and spherically symmetric colloids, but patchy colloids do not attract patchy colloids and spherically symmetric colloids do not attract spherically symmetric colloids. This results in the temperature, density, and composition dependent reversible self assembly of the mixture into colloidal star molecules. This type of mixture has been recently synthesized by grafting of complimentary single stranded DNA [L. Feng, R. Dreyfus, R. Sha, N. C. Seeman, and P. M. Chaikin, Adv. Mater. 25(20), 2779-2783 (2013)]. As a quantitative test of the theory, we perform new monte carlo simulations to study the self assembly of these mixtures; theory and simulation are found to be in excellent agreement.

Marshall, Bennett D.; Chapman, Walter G.

2013-09-01

208

Molecular theory for self assembling mixtures of patchy colloids and colloids with spherically symmetric attractions: The single patch case.  

PubMed

In this work we develop a new theory to model self assembling mixtures of single patch colloids and colloids with spherically symmetric attractions. In the development of the theory we restrict the interactions such that there are short ranged attractions between patchy and spherically symmetric colloids, but patchy colloids do not attract patchy colloids and spherically symmetric colloids do not attract spherically symmetric colloids. This results in the temperature, density, and composition dependent reversible self assembly of the mixture into colloidal star molecules. This type of mixture has been recently synthesized by grafting of complimentary single stranded DNA [L. Feng, R. Dreyfus, R. Sha, N. C. Seeman, and P. M. Chaikin, Adv. Mater. 25(20), 2779-2783 (2013)]. As a quantitative test of the theory, we perform new monte carlo simulations to study the self assembly of these mixtures; theory and simulation are found to be in excellent agreement. PMID:24050362

Marshall, Bennett D; Chapman, Walter G

2013-09-14

209

Uncovering the single top: observation of electroweak top quark production  

SciTech Connect

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.

Benitez, Jorge Armando; /Michigan State U.

2009-08-01

210

Inflation in spherically symmetric inhomogeneous models  

SciTech Connect

Exact analytical solutions of Einstein's equations are found for a spherically symmetric inhomogeneous metric in the presence of a massless scalar field with a flat potential. The process of isotropization and homogenization is studied in detail. It is found that the time dependence of the metric becomes de Sitter for large times. Two cases are studied. The first deals with a homogeneous scalar field, while the second with a spherically symmetric inhomogeneous scalar field. In the former case the metric is of the Robertson-Walker form, while the latter is intrinsically inhomogeneous. 16 refs.

Stein-Schabes, J.A.

1986-11-01

211

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

SciTech Connect

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.

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

2000-06-21

212

Complex PT-symmetric nonlinear Schrödinger equation and Burgers equation.  

PubMed

The complex -symmetric nonlinear wave models have drawn much attention in recent years since the complex -symmetric extensions of the Korteweg-de Vries (KdV) equation were presented in 2007. In this review, we focus on the study of the complex -symmetric nonlinear Schrödinger equation and Burgers equation. First of all, we briefly introduce the basic property of complex symmetry. We then report on exact solutions of one- and two-dimensional nonlinear Schrödinger equations (known as the Gross-Pitaevskii equation in Bose-Einstein condensates) with several complex -symmetric potentials. Finally, some complex -symmetric extension principles are used to generate some complex -symmetric nonlinear wave equations starting from both -symmetric (e.g. the KdV equation) and non- -symmetric (e.g. the Burgers equation) nonlinear wave equations. In particular, we discuss exact solutions of some representative ones of the complex -symmetric Burgers equation in detail. PMID:23509385

Yan, Zhenya

2013-03-18

213

A design technique for symmetric dualband filters  

Microsoft Academic Search

This work describes a method for designing a class of microwave filters presenting a rejection bandwidth inside the passband; these filters are then characterized by two passbands separated by a stopband, which is created by suitably inserting transmission zeros inside the original passband. In case of passbands of equal extension and with the stopband symmetrically displaced between the passbands, the

Giuseppe Macchiarella; Stefano Tamiazzo

2005-01-01

214

Design of Rotationally Symmetric Triode Electron Guns.  

National Technical Information Service (NTIS)

The properties of the symmetric triode electron gun are given in design rules as a function of its geometry and the applied potentials. A numerical method to simulate electron guns is described. The simulation is sufficiently accurate to replace a large n...

M. H. L. M. Vandenbroek

1986-01-01

215

Unidirectional nonlinear PT-symmetric optical structures  

SciTech Connect

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.

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

216

Introduction to left-right symmetric models.  

National Technical Information Service (NTIS)

We motivate left-right symmetric models by the possibility of spontaneous parity breaking. Then we describe the multiplets and the Lagrangian of such models. Finally we discuss lower bounds on the right-handed scale. (author). (Atomindex citation 25:01224...

W. Grimus

1993-01-01

217

Left-Right Symmetric Electroweak Models.  

National Technical Information Service (NTIS)

We present a critical analysis of the spontaneous symmetry breaking and the Higgs sector of the conventional SU(2)(sub L)(circle times)SU(2)(sub R)(circle times)U(1)(sub B-L) left-right symmetric theory involving bi-doublet and triplet Higgs fields. We ex...

F. I. Olness

1989-01-01

218

Multifrontal parallel distributed symmetric and unsymmetric solvers  

Microsoft Academic Search

We consider the solution of both symmetric and unsymmetric systems of sparse linear equations. A new parallel distributed memory multifrontal approach is described. To handle numerical pivoting efficiently, a parallel asynchronous algorithm with dynamic scheduling of the computing tasks has been developed. We discuss some of the main algorithmic choices and compare both implementation issues and the performance of the

P. R. Amestoy; I. S. Duff; J.-Y. L'Excellent

2000-01-01

219

Multifrontal parallel distributed symmetric and unsymmetric solvers  

Microsoft Academic Search

We consider the solution of both symmetric and unsymmetric systems of sparselinear equations. A new parallel distributed memory multifrontal approach isdescribed. To handle numerical pivoting efficiently, a parallel asynchronousalgorithm with dynamic scheduling of the computing tasks has been developed. Wediscuss some of the main algorithmic choices and compare both implementationissues and the performance of the LDLTand LU factorizations. Performanceanalysis on

P. R. Amestoy; I. S. Duff; J Y L'Excellent

1998-01-01

220

Symmetrical connector for solar panel arrays  

Microsoft Academic Search

The disclosed symmetrical plug and socket connector may be installed in a solar panel array so that the connector is directed towards the adjacent panel for forming an interconnect by the shortest possible route. The connector socket is an elongated, substantially rectangular housing having a groove formed about the entire periphery thereof adjacent one side and an annular bore extending

Bunnell

1981-01-01

221

REAL FORMS OF HERMITIAN SYMMETRIC SPACES1  

Microsoft Academic Search

Introduction. The results we give here only begin to answer the follow­ ing general problems: Let AT be a hermitian symmetric domain, T a group acting holomorphically and discontinuously, and U = T\\\\X the quotient. Then, by Kodaira if U is compact and smooth, or, by Baily-Borel if just {\\/has finite volume (and T arithmetic), U is algebraic. One can

HARRIS A. JAFFEE

222

Symmetric space description of carbon nanotubes  

NASA Astrophysics Data System (ADS)

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 parametrization 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) × U(1)] belonging to the DIII-odd Cartan class. We rederive the leading-order correction to the conductance of the perfectly conducting channel \\langle \\ln \\delta g \\rangle and its variance Var(ln ?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 \\mathrm {Var}(\\ln \\delta g)/\\langle \\ln \\delta g\\rangle , and as a by-product a novel expression for the localization length for the most general case of a symmetric space with BCm root system, in which all three types of roots are present.

Caselle, Michele; Magnea, Ulrika

2006-01-01

223

Dissociative Recombination of Highly Symmetric Polyatomic Ions  

NASA Astrophysics Data System (ADS)

A general first-principles theory of dissociative recombination is developed for highly symmetric molecular ions and applied to H3O+ and CH3+, which play an important role in astrophysical, combustion, and laboratory plasma environments. The theoretical cross sections obtained for the dissociative recombination of the two ions are in good agreement with existing experimental data from storage ring experiments.

Douguet, Nicolas; Orel, Ann E.; Greene, Chris H.; Kokoouline, Viatcheslav

2012-01-01

224

ECG compression using discrete symmetric wavelet transform  

Microsoft Academic Search

This paper proposes a new ECG signal compression algorithm using a discrete symmetric wavelet transform. This proposed compression scheme may find applications in digital Holter recording, in ECG signal archiving and in ECG data transmission through communication channels. Using the new method, a compression ratio of 8 to 1 can be achieved with PRD=3.9%, in contrast to the AZTEC compression

A. Djohan; T. Q. Nguyen; W. J. Tompkins

1995-01-01

225

Cylindrically symmetric solutions in conformal gravity  

SciTech Connect

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.

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

226

Convexity and symmetrization in relativistic theories  

NASA Astrophysics Data System (ADS)

There is a strong motivation for the desire to have symmetric hyperbolic field equations in thermodynamics, because they guarantee well-posedness of Cauchy problems. A generic quasi-linear first order system of balance laws — in the non-relativistic case — can be shown to be symmetric hyperbolic, if the entropy density is concave with respect to the variables. In relativistic thermodynamics this is not so. This paper shows that there exists a scalar quantity in relativistic thermodynamics whose concavity guarantees a symmetric hyperbolic system. But that quantity — we call it —bar h — is not the entropy, although it is closely related to it. It is formed by contracting the entropy flux vector — ha with a privileged time-like congruencebar ? _? . It is also shown that the convexity of h plus the requirement that all speeds be smaller than the speed of light c provide symmetric hyperbolic field equations for all choices of the direction of time. At this level of generality the physical meaning of —h is unknown. However, in many circumstances it is equal to the entropy. This is so, of course, in the non-relativistic limit but also in the non-dissipative relativistic fluid and even in relativistic extended thermodynamics for a non-degenerate gas.

Ruggeri, T.

1990-09-01

227

A Maple Package for Symmetric Functions  

Microsoft Academic Search

We describe the man features of a package of Maple programs for manipulating symmetric polynomials and related structures. Among the highlights of the package are (1) a collection of procedures for converting between polynomial expressions involving several fundamental bases, and (2) a general mechanism that allows the user to easily add new bases to the existing collection. The latter facilitates

John R. Stembridge

1995-01-01

228

Asymmetric Versus Symmetric Pulses for Cortical Microstimulation  

Microsoft Academic Search

Intracortical microstimulation (ICMS), which has shown promise in the visual, auditory and somatosensory sys- tems as a platform for sensory prostheses, typically relies on charged balanced, symmetric, biphasic stimulation. However, neural stimulation models as well as experiments conducted in cochlear implant users have suggested that charge balanced asymmetric pulses could generate lower detection thresholds for stimulation in terms of charge

Andrew S. Koivuniemi; Kevin J. Otto

2011-01-01

229

Symmetrization of cyclic sigma-telluranes  

SciTech Connect

The authors examine reactions involving cyclic sigma-telluranes. Refluxing 5,5-dichlorodibenzotellurophene with tellurium tetrachloride in o-dichlorobenzene results in symmetrization and the formation of 2,2'-bis(trichlorotelluro)diphenyl in high yield. The other compounds formed and described are polymeric ditelluride, dibenzotellurophene, and dimethyltellurium dibromide.

Sadekov, I.D.; Rivkin, B.B.; Maslakov, A.G.; Minkin, V.I.

1987-09-01

230

Resonances for Symmetric Two-Barrier Potentials  

ERIC Educational Resources Information Center

|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…

Fernandez, Francisco M.

2011-01-01

231

Models of helically symmetric binary systems  

NASA Astrophysics Data System (ADS)

Results from helically symmetric scalar-field models and first results from a convergent helically symmetric binary neutron-star code are reported here; these are models stationary in the rotating frame of a source with constant angular velocity ?. In the scalar-field models and the neutron-star code, helical symmetry leads to a system of mixed elliptic hyperbolic character. The scalar-field models involve nonlinear terms of the form ?3, (??)2 and ?squ? that mimic nonlinear terms of the Einstein equation. Convergence is strikingly different for different signs of each nonlinear term; it is typically insensitive to the iterative method used, and it improves with an outer boundary in the near zone. In the neutron-star code, one has no control on the sign of the source, and convergence has been achieved only for an outer boundary less than ~1 wavelength from the source or for a code that imposes helical symmetry only inside a near zone of that size. The inaccuracy of helically symmetric solutions with appropriate boundary conditions should be comparable to the inaccuracy of a waveless formalism that neglects gravitational waves, and the (near zone) solutions we obtain for waveless and helically symmetric BNS codes with the same boundary conditions nearly coincide.

Yoshida, Shin'ichirou; Bromley, Benjamin C.; Read, Jocelyn S.; Uryu, Koji; Friedman, John L.

2006-08-01

232

Realizability of stationary spherically symmetric transonic accretion.  

PubMed

The spherically symmetric stationary transonic (Bondi) flow is considered a classic example of an accretion flow. This flow, however, is along a separatrix, which is usually not physically realizable. We demonstrate, using a pedagogical example, that it is the dynamics which selects the transonic flow. PMID:12513398

Ray, Arnab K; Bhattacharjee, J K

2002-12-10

233

Regeneration of Symmetrical Hindlimbs in Larval Salamanders  

Microsoft Academic Search

The complete circle rule of the polar coordinate model of pattern regulation was tested for regenerating hindlimbs of Ambystoma larvae. The hindlimbs were made symmetrical in the circumference of either the thigh or the shank, and their ability to regenerate from both levels was observed. Thighs composed of two anterior halves failed to regenerate, whereas thighs composed of two posterior

David L. Stocum

1978-01-01

234

Conversion Functions for Symmetric Key Ciphers  

Microsoft Academic Search

As a general design criterion, a symmetric key cipher should not be closed under functional com- position due to the implications on the security of the cipher. However, there are scenarios in which this prop- erty is desirable and can be obtained without reducing the security of a cipher by increasing the computational workload of the cipher. We expand the

Debra L. Cook; Angelos D. Keromytis

235

Geometrical Symmetry in Symmetric Galerkin BEM.  

National Technical Information Service (NTIS)

We consider a symmetric boundary integral formulation associated with a mixed boundary value problem defined on a domain Omega is an element of the set of real numbers(2) with piecewise smooth boundary Gamma. We assume that Omega is mapped onto itself by ...

A. Aimi M. Diligenti

2001-01-01

236

Resonances for Symmetric Two-Barrier Potentials  

ERIC Educational Resources Information Center

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…

Fernandez, Francisco M.

2011-01-01

237

Symmetric Stereo Matching for Occlusion Handling  

Microsoft Academic Search

In this paper, we propose a symmetric stereo model to han- dle occlusion in dense two-frame stereo. Our occlusion reasoning is directly based on the visibility constraint that is more general than both ordering and uniqueness con- straints used in previous work. The visibility constraint requires occlusion in one image and disparity in the other to be consistent. We embed

Jian Sun; Yin Li; Sing Bing Kang; Heung-Yeung Shum

2005-01-01

238

Iris Recognition Using Circular Symmetric Filters  

Microsoft Academic Search

This paper proposes a new method for personal identification based on iris recognition. The method consists of three major components: image preprocessing, feature extraction and classifier design. A bank of circular symmetric filters is used to capture local iris characteristics to form a fixed length feature vector. In iris matching, an efficient approach called nearest feature line (NFL) is used.

Li Ma; Yunhong Wang; Tieniu Tan

2002-01-01

239

Rounding in Symmetric Matrices and Undirected Graphs  

Microsoft Academic Search

We consider the problem of rounding the entries of a matrix without distorting the row, column, and grand totals. This problem arises in controlling statistical disclosure, in data analysis, and elsewhere. There are algorithms in the literature which produce roundings that are “tight” in the sense of distorting the totals very little. We concentrate on the case of symmetric matrices.

Pavol Hell; David G. Kirkpatrick; Brenda Li

1996-01-01

240

Reducing the bandwidth of sparse symmetric matrices  

Microsoft Academic Search

The finite element displacement method of analyzing structures involves the solution of large systems of linear algebraic equations with sparse, structured, symmetric coefficient matrices. There is a direct correspondence between the structure of the coefficient matrix, called the stiffness matrix in this case, and the structure of the spatial network delineating the element layout. For the efficient solution of these

E. Cuthill; J. McKee

1969-01-01

241

Circular symmetrization and extremal Robin conditions  

Microsoft Academic Search

: We study the average temperature in a homogeneous disk subject touniform heating in its interior and Newton's law of cooling, hv + @v=@n = 0, onits boundary. More precisely, among those h taking values in a prescribed interval,and of prescribed mean, we identify the minimizer and a maximizer of the averagetemperature. The latter characterization makes use of circular symmetrization.

Steven J. Cox; Bernhard Kawohl

1999-01-01

242

Cracked Shells under Skew-Symmetric Loading.  

National Technical Information Service (NTIS)

The general problem of a shell containing a through crack in one of the principal planes of curvature and under general skew-symmetric loading is considered. By employing a Reissner type shell theory which takes into account the effect of transverse shear...

F. Delale

1981-01-01

243

Rule learning approaches for symmetric multiplayer games  

Microsoft Academic Search

This paper describes a series of experiments involving rule learning for Samurai, a symmetric multiplayer strategy game. Rule based artificial intelligence is commonly used in a wide variety of computer strategy games. Automated rule learning processes have been used to derive rules both to improve the quality of AI play and to illuminate possible strategies and tactics for the games.

John Rushing; John Tiller

2011-01-01

244

Nearly diffraction-limited size flat-top laser beam shaper  

Microsoft Academic Search

A diffractive optical element (DOE) is designed with a new algorithm for transforming a rotationally symmetrical Gaussian beam into a nearly diffraction-limited flat-top by Fourier transformation system. The simulating results indicate that size of the shaped spot is only twice more than one of the diffraction limited spot, the diffraction efficiency is about 71.38$ and the edge of the uniform

Fengyou Li; Zhenwu Lu; Hongjun Li; Jianghong Liao

2000-01-01

245

Boron-enriched star-shaped molecule via cycloaddition reaction.  

PubMed

The facile synthesis of a thermally stable carborane appended symmetrical star-shaped molecule having six bulky o-carborane clusters on the periphery, thereby containing sixty boron atoms was accomplished via a cobalt-catalyzed [2+2+2] cycloaddition reaction. PMID:19587935

Prasanna Dash, Barada; Satapathy, Rashmirekha; Maguire, John A; Hosmane, Narayan S

2009-05-06

246

Kowalevski top in quantum mechanics  

NASA Astrophysics Data System (ADS)

The quantum mechanical Kowalevski top is studied by the direct diagonalization of the Hamiltonian. The spectra show different behaviors depending on the region divided by the bifurcation sets of the classical invariant tori. Some of these spectra are nearly degenerate due to the multiplicity of the invariant tori. The Kowalevski top has several symmetries and symmetry quantum numbers can be assigned to the eigenstates. We have also carried out the semiclassical quantization of the Kowalevski top by the EBK formulation. It is found that the semiclassical spectra are close to the exact values, thus the eigenstates can be also labeled by the integer quantum numbers. The symmetries of the system are shown to have close relations with the semiclassical quantum numbers and the near-degeneracy of the spectra.

Matsuyama, A.

2013-09-01

247

Consider topped crude for FCC  

SciTech Connect

A case study is presented that illustrates the mechanics for evaluating use of topped crude to load the FCC for more profit. Declining product demands combined with high crude costs has shut down many refineries and left others operting well below design capacity. The study illustrates the step-by-step requirements to debottleneck an existing Kellogg Orthoflow Model B FCC to process topped crude mixed with gas oils. This study was limited to the catalytic converter defined as the reactor, regenerator, air blower, and wet gas compressor. The scope was to examine the ability to process topped crude and to consider modernizing the FCC to employ riser cracking and complete CO combustion regeneration.

Louder, K.E.; Juno, E.J.; Kulapaditharom, L.

1985-09-01

248

RNAi triggered by symmetrically transcribed transgenes in Drosophila melanogaster.  

PubMed Central

Specific silencing of target genes can be induced in a variety of organisms by providing homologous double-stranded RNA molecules. In vivo, these molecules can be generated either by transcription of sequences having an inverted-repeat (IR) configuration or by simultaneous transcription of sense-antisense strands. Since IR constructs are difficult to prepare and can stimulate genomic rearrangements, we investigated the silencing potential of symmetrically transcribed sequences. We report that Drosophila transgenes whose sense-antisense transcription was driven by two convergent arrays of Gal4-dependent UAS sequences can induce specific, dominant, and heritable repression of target genes. This effect is not dependent on a mechanism based on homology-dependent DNA/DNA interactions, but is directly triggered by transcriptional activation and is accompanied by specific depletion of the endogenous target RNA. Tissue-specific induction of these transgenes restricts the target gene silencing to selected body domains, and spreading phenomena described in other cases of post-transcriptional gene silencing (PTGS) were not observed. In addition to providing an additional tool useful for Drosophila functional genomic analysis, these results add further strength to the view that events of sense-antisense transcription may readily account for some, if not all, PTGS-cosuppression phenomena and can potentially play a relevant role in gene regulation.

Giordano, Ennio; Rendina, Rosaria; Peluso, Ivana; Furia, Maria

2002-01-01

249

R-Symmetric Gauge Mediation and the Minimal R-Symmetric Supersymmetric Standard Model  

NASA Astrophysics Data System (ADS)

This is an invited summary of a seminar talk given at various institutions in the United States and Canada. After a brief introduction, a review of the minimal R-symmetric supersymmetric standard model is given, and the benefits to the flavor sector are discussed. R-symmetric gauge mediation is an attempt to realize this model using metastable supersymmetry breaking techniques. Sample low energy spectra are presented and tuning is discussed. Various other phenomenological results are summarized.

Blechman, Andrew E.

250

Top Mass Measurements at the Tevatron  

SciTech Connect

We present the latest measurements of the top quark mass from the Tevatron. The different top decay channels and measurement techniques used for these results are also described. The world average of the top quark mass based on some of these new results combined with previous results is m{sub top} = 172.6 {+-} 1.4 GeV.

Wang, M.H.L.S.; /Fermilab

2009-04-01

251

Top-k Combinatorial Skyline Queries  

Microsoft Academic Search

\\u000a The problem of top-k skyline computation has attracted considerable research attention in the past few years. Given a dataset, a top-k skyline returns k “most interesting” skyline tuples based on some kind of preference specified by the user. We extend the concept of top-k skyline to a so-called top-k combinatorial skyline query (k-CSQ). In contrast to the existing top-k skyline

I-Fang Su; Yu-Chi Chung; Chiang Lee

2010-01-01

252

Top quark production at the Tevatron  

SciTech Connect

The Fermilab Tevatron has, until recently, been the only accelerator with sufficient energy to produce top quarks. The CDF and D0 experiments have collected large samples of top quarks. We report on recent top quark production measurements of the single top and t{bar t} production cross sections, as well as studies of the t{bar t} invariant mass distribution and a search for highly boosted top quarks.

Varnes, Erich W.; /Arizona U.

2010-09-01

253

Observation of the top quark  

SciTech Connect

The D{O} 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 -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 {+-} 0.6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2 x 10{sup -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 -21}{sup +19} (stat.) {+-}22 (syst.) GeV/c{sup 2}1 and its production cross section to be 6.4 {+-} 2.2 pb. Other decay channels are under study such as the t{bar t} to all-jets channel which might yield additional information about the top quark.

Bantly, J. [Brown Univ., Providence, RI (United States)

1995-10-01

254

The 2003 Training Top 100.  

ERIC Educational Resources Information Center

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…

Galvin, Tammy

2003-01-01

255

The 2002 Training Top 100.  

ERIC Educational Resources Information Center

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…

Training, 2002

2002-01-01

256

Prospects for top at CDF  

SciTech Connect

During the next two years, the Fermilab Tavatron is expected to deliver approximately 100pb{sup {minus}1} of integrated luminosity. We describe improvements to the CDF detector since the 1988--89 collider run and discuss the prospects for the discovery of the top quark during the 1992--93 collider runs.

Gerdes, D. (Chicago Univ., IL (United States))

1992-06-03

257

The Top STEM Degree Producers  

ERIC Educational Resources Information Center

|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…

Diverse: Issues in Higher Education, 2012

2012-01-01

258

"Top School Problems" Are Myths.  

ERIC Educational Resources Information Center

A well-known "study" comparing the top school problems of 1940 (talking and gum chewing) with those of 1987 (drug abuse, pregnancy, and violence) is nonexistent. In 1940, 49 percent of all youth did not finish high school, 37,000 teenagers died from violence or disease, and 335,000 teens gave birth. Educators should discount pastoral memories and…

Males, Mike

1992-01-01

259

Review of Top Quark Physics  

Microsoft Academic Search

We present an overview of Top Quark Physics - from what has been learned so far at the Tevatron, to the searches that lie ahead at present and future colliders. We summarize the richness of the measurements and discuss their possible impact on our understanding of the Standard Model by pointing out their key elements and limitations. When possible, we

Dhiman Chakraborty; Jacobo Konigsberg; David Rainwater

260

Conservation: Top predators and biodiversity  

Microsoft Academic Search

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

Fabrizio Sergio; Ian Newton; Luigi Marchesi

2005-01-01

261

TOPS: A Multigroup Opacity Code.  

National Technical Information Service (NTIS)

From T-4 Opacity Library Data, the TOPS code calculates multigroup opacities that can be written in a variety of formats for use in radiation transport codes. Arbritary mixture of any elements for which OPLIB data exist is supported. Versions of the code ...

J. Abdallah R. E. H. Clark

1985-01-01

262

Top Jets at the LHC  

SciTech Connect

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.

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

2008-10-06

263

Metal-molecule-semiconductor heterostructure devices  

NASA Astrophysics Data System (ADS)

The present work focuses on Au-molecule-GaAs heterostructures. Stable monolayers of various molecules were self-assembled on p+ GaAs using a chemical etch to overcome GaAs surface oxidation during SAM formation. FTIR and ellipsometry measurements indicate uniform, crystalline and reasonably thick monolayers. A low energy, indirect path technique was used to evaporate Au onto the molecular layer without damaging or penetrating it. Room temperature, four probe I-V measurements on the Au-molecule-GaAs devices indicate a substantial increase in conductivity due to the presence of the molecular layer and more symmetric curves than for Au-GaAs control samples. Variable temperature I-V measurements show little temperature dependence, also in contrast to the Au-GaAs samples. The temperature dependent I-V measurements, along with the relatively symmetric I-V's in forward and reverse-bias directions, indicate that current transport through tunneling dominates in case of the alkane-chain devices. These observations can be qualitatively explained in terms of the electrostatic properties and density of states of the molecular layers. The presence of the molecular layer lowers the effective barrier height due to the relatively low dielectric constant of the molecules and, in some cases, the net dipole moment of the molecules. High current densities indicate that the molecular layers have relatively high densities of states near the metal Fermi level and that strong coupling has been achieved between the contacts and the molecules. Effects of molecular dipole, length and presence of methylene groups have also been studied.

Lodha, Saurabh

2004-03-01

264

Binary switching in a 'symmetric' potential landscape  

PubMed Central

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.

Roy, Kuntal; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

2013-01-01

265

Binary switching in a 'symmetric' potential landscape.  

PubMed

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

Roy, Kuntal; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

2013-10-24

266

PT-symmetric representations of fermionic algebras  

SciTech Connect

A recent paper by Jones-Smith and Mathur, Phys. Rev. A 82, 042101 (2010) extends PT-symmetric quantum mechanics from bosonic systems (systems for which T{sup 2}=1) to fermionic systems (systems for which T{sup 2}=-1). The current paper shows how the formalism developed by Jones-Smith and Mathur can be used to construct PT-symmetric matrix representations for operator algebras of the form {eta}{sup 2}=0, {eta}{sup 2}=0, {eta}{eta}+{eta}{eta}={alpha}1, where {eta}={eta}{sup PT}=PT{eta}T{sup -1}P{sup -1}. It is easy to construct matrix representations for the Grassmann algebra ({alpha}=0). However, one can only construct matrix representations for the fermionic operator algebra ({alpha}{ne}0) if {alpha}=-1; a matrix representation does not exist for the conventional value {alpha}=1.

Bender, Carl M. [Physics Department, Washington University, St. Louis, Missouri 63130 (United States); Klevansky, S. P. [Institut fuer Theoretische Physik, Universitaet Heidelberg, Philosophenweg 19, D-69120 Heidelberg (Germany)

2011-08-15

267

Numerical Investigation of Symmetric and Asymmetric Periodic Oscillations  

Microsoft Academic Search

Global information for the periodic solutions --- symmetric and asymmetric --- of the `gravitational' spring-pendulum problem is given for the first time. For two different sets of the parameters of this problem, the families of symmetric periodic solutions which emanate from the equilibrium point have been determined. Further families of asymmetric and symmetric solutions which bifurcate from them have also

P. G. Kazantzis

1981-01-01

268

Symmetrically reduced Galileon equations and solutions  

NASA Astrophysics Data System (ADS)

The maximally complicated arbitrary-dimensional “maximal” Galileon field equations simplify dramatically for symmetric configurations. Thus, spherical symmetry reduces the equations from the D- to the two-dimensional (Monge-Ampere) equation, axial symmetry to its cubic extension, etc. We can then obtain explicit solutions, such as spherical or axial waves, and relate them to the (known) general, but highly implicit, lower-D solutions.

Deser, S.; Franklin, J.

2012-08-01

269

Index-based symmetric DNA encryption algorithm  

Microsoft Academic Search

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

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

2011-01-01

270

Solitons in PT-symmetric nonlinear lattices  

SciTech Connect

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.

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

271

Cellular Programming and Symmetric Key Cryptography Systems  

Microsoft Academic Search

The problem of designing symmetric key cryptography algorithms based upon cellular automata (CAs) is considered. The reliability\\u000a of the Vernam cipher used in the process of encryption highly depends on a quality of used random numbers. One dimensional,\\u000a nonuniform CAs is considered as a generator of pseudorandom number sequences (PNSs). The quality of PNSs highly depends on\\u000a a set of

Franciszek Seredynski; Pascal Bouvry; Albert Y. Zomaya

2003-01-01

272

Wave equation on spherically symmetric Lorentzian metrics  

SciTech Connect

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.

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

273

Tilted Cylindrically Symmetric Self-Similar Solutions  

NASA Astrophysics Data System (ADS)

This paper is devoted to explore tilted kinematic self-similar solutions of the the general cylindrical symmetric spacetimes. These solutions are of the first, zeroth, second and infinite kinds for the perfect fluid and dust cases. Three different equations of state are used to obtain these solutions. We obtain a total of five independent solutions. The correspondence of these solutions with those already available in the literature is also given.

Sharif, M.; Sultan, S.

2009-06-01

274

Chirally symmetric but confining dense, cold matter  

SciTech Connect

The folklore tradition about the QCD phase diagram is that at the chiral restoration phase transition at finite density hadrons are deconfined and there appears the quark matter. We address this question within the only known exactly solvable confining and chirally symmetric model. It is postulated within this model that there exists linear Coulomb-like confining interaction. The chiral symmetry breaking and the quark Green function are obtained from the Schwinger-Dyson (gap) equation while the color-singlet meson spectrum results from the Bethe-Salpeter equation. We solve this model at T=0 and finite chemical potential {mu} and obtain a clear chiral restoration phase transition at the critical value {mu}{sub cr}. Below this value the spectrum is similar to the previously obtained one at {mu}=0. At {mu}>{mu}{sub cr} the quarks are still confined and the physical spectrum consists of bound states which are arranged into a complete set of exact chiral multiplets. This explicitly demonstrates that a chirally symmetric matter consisting of confined but chirally symmetric hadrons at finite chemical potential is also possible in QCD. If so, there must be nontrivial implications for astrophysics.

Glozman, L. Ya.; Wagenbrunn, R. F. [Institute for Physics, Theoretical Physics Branch, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria)

2008-03-01

275

Asymmetric versus symmetric pulses for cortical microstimulation.  

PubMed

Intracortical microstimulation (ICMS), which has shown promise in the visual, auditory and somatosensory systems as a platform for sensory prostheses, typically relies on charged balanced, symmetric, biphasic stimulation. However, neural stimulation models as well as experiments conducted in cochlear implant users have suggested that charge balanced asymmetric pulses could generate lower detection thresholds for stimulation in terms of charge per phase. For this study, rats were chronically implanted with microelectrode arrays unilaterally in their right auditory cortex and then trained to detect ICMS delivered through a single electrode site in order to determine their behavioral threshold. This model was used in two experiments. The first experiment addressed the effect of lead phase direction, asymmetry, and phase duration on detection threshold. The second experiment fixed the cathode phase duration at 123 ?s and varied only the phase asymmetry and lead phase direction. Taken together, the results of these experiments suggest that, for ICMS, the primary determinant of threshold level is cathode phase duration, and that asymmetry provides no significant advantage when compared to symmetric, cathode leading pulses. However, symmetric anode leading pulses of less than or equal to 205 ?s per phase consistently showed higher thresholds when compared to all other pulses of equal cathode phase duration. PMID:21968793

Koivuniemi, Andrew S; Otto, Kevin J

2011-10-03

276

Symmetric multilayer megampere X-pinch  

SciTech Connect

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.

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

277

Properties of the Top Quark  

SciTech Connect

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.

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

2009-08-01

278

High-resolution direct-absorption spectroscopy of hydroxymethyl radical in the CH symmetric stretching region.  

PubMed

High-resolution, fully rotationally resolved direct absorption spectra of hydroxymethyl radical, CH2OH, are presented in the infrared CH stretching region. As a result of low rotational temperatures and sub-Doppler linewidths obtained in the slit supersonic expansion, the Ka = 0 ? 0 band of the symmetric CH stretch for CH2OH has been unambiguously identified and analyzed. By way of chemical confirmation, hydroxymethyl radical is generated via two different slit jet discharge syntheses: (i) direct dissociation of CH3OH to form CH2OH and (ii) dissociation of Cl2 followed by the radical H atom extraction reaction Cl + CH3OH ? HCl + CH2OH. The identified transitions are fit to a Watson A-reduced symmetric top Hamiltonian to yield first precision experimental values for the ground state rotational constants as well as improved values for the symmetric stretch rotational constants and vibrational band origin. The results both complement and substantially improve upon spectral efforts via previous double resonance ionization detected infrared methods by Feng et al. [J. Phys. Chem. A, 2004, 108, 7093], as well as offer high-resolution predictions for laboratory and astronomical detection of hydroxymethyl radical in the millimeter-wave region. PMID:23470104

Roberts, Melanie A; Sharp-Williams, Erin N; Nesbitt, David J

2013-03-07

279

Single top at the Tevatron  

SciTech Connect

The authors review the status of the search for the electroweak production of single top quarks by the CDF and D0 collaborations at the Fermilab Tevatron proton-antiproton collider using Run II data. With a dataset of approximately 160 pb{sup -1} for CDF and 230 pb{sup -1} for D0, neither experiment finds evidence for single top production and sets 95% C.L. upper limits on the production cross-sections. The CDF limits are 10.1 pb for the t channel, 13.6 pb for the s channel and 17.8 pb for the combined production cross-sections of s and t channel. The D0 limits are 5.0 pb for the t channel, 6.4 pb for the s-channel production cross-sections. Both experiments investigate the prospect for a 3{sigma} evidence and a 5{sigma} discovery.

Taffard, Anyes; /Illinois U., Urbana

2005-11-01

280

Scalar top study: Detector optimization  

SciTech Connect

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).

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

2006-09-01

281

Trifluralin Transfer from Top Soil  

Microsoft Academic Search

Leaching of14C-ring-labeled technical trifluralin from the top 5 cm of soil was followed in a microlysimeter experiment under outdoor conditions. Leaching of water residues from soil was low and represented 2.2, 5.4, and 6.7% of the applied radioactivity after 6, 12, and 18 months, respectively. Two degradation products, called A and B, were clearly detected and represented about 80 and

F. Malterre; J. G. Pierre; M. Schiavon

1998-01-01

282

Observation of the top quark  

SciTech Connect

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.

Greenlee, H.; D0 Collaboration

1995-05-01

283

Observation of the Top Quark  

SciTech Connect

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.

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

284

Observation of the top quark  

SciTech Connect

The D0 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.

Klima, B.; D0 Collaboration

1995-05-01

285

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

PubMed

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

Hou, Xu; Zhang, Huacheng; Jiang, Lei

2012-04-13

286

Intracellular delivery of top-down fabricated tunable nano-plasmonic resonators.  

PubMed

Engineered plasmonic structures fabricated using top-down technologies have demonstrated huge enhancements in the optical response of molecules, including Raman scattering. However, providing a sufficient number of such top-down fabricated nanostructures in solution has been a nontrivial task which has limited their potential in intracellular applications. Here we report the development of a protocol for the intracellular delivery of tunable nanoplasmonic resonators fabricated via scalable top-down techniques. This offers excellent possibilities towards the real-time parallel optical detection of intracellular molecular events. PMID:24056760

Ota, Sadao; Wang, Sheng; Ryu, Jongeun; Wang, Yuan; Chen, Yong; Zhang, Xiang

2013-09-13

287

Top Quark Mass: Past, Present and Future.  

National Technical Information Service (NTIS)

The top quark is the most massive elementary particle discovered thus far. Its large mass may help explain the mechanism by which fundamental particles gain mass - the Standard Model's greatest standing mystery. Today the top quark mass, together with the...

G. Guitierrez

2006-01-01

288

Characterisation of an AGATA symmetric prototype detector  

NASA Astrophysics Data System (ADS)

The Advanced GAmma Tracking Array (AGATA) symmetric prototype detector has been tested at the University of Liverpool. A 137Ce source, collimated to a 2 mm diameter, was scanned across the front face of the detector and data were acquired utilising digital electronics. Pulse shapes from a selection of well-defined photon interaction positions have been analysed to investigate the position sensitivity of the detector. Furthermore, the application of the electric field simulation software, Multi Geometry Simulation (MGS) to generate theoretical pulse shapes for AGATA detectors has been presented.

Nelson, L.; Dimmock, M. R.; Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Nolan, P. J.; Lazarus, I.; Simpson, J.; Medina, P.; Santos, C.; Parisel, C.

2007-04-01

289

Thermal buckling of symmetrically laminated composite plates  

NASA Astrophysics Data System (ADS)

This paper discusses an investigation into the thermal buckling of symmetrically laminated composite plates. In this study thermal buckling is investigated for laminates under two different simple support conditions, fixed and sliding. These laminates are subjected to the conditions of a uniform temperature change, and a temperature change varying linearly along the length of the plate. The effects of the principal material axes not being aligned with the edges of the plate are also investigated. The buckling response is studied using variational methods, specifically the Trefftz criterion. A Rayleigh-Ritz formulation is used to obtain numerical results from the formulations for the prebuckling response and the buckling response.

Meyers, C. A.; Hyer, M. W.

290

Expanding symmetric multiprocessor capability through gang scheduling  

SciTech Connect

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.

Jette, M.A.

1998-03-01

291

Design of spherical symmetric gradient index lenses  

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

292

Synthesis of symmetrical and nonsymmetrical bisthienylcyclopentenes.  

PubMed

Diarylethenes possess unique structural properties, which enabled them to find widespread applications in the field of photochromism. Nowadays, bisthienylcyclopentenes (BTCs) present the most popular subfamily of these compounds, which are widely used as P-type chromophores. This minireview summarises the main strategies for the synthesis of symmetrical and nonsymmetrical BTCs. In addition, attention is drawn to desymmetrisations achieved by monosubstitutions, which is not frequently utilised, although it can be highly advantageous. This is supported with some of the authors' latest results. PMID:23943569

Szalóki, György; Pozzo, Jean-Luc

2013-08-19

293

Matrix isolation ESR spectroscopy and magnetic anisotropy of D3h symmetric septet trinitrenes  

NASA Astrophysics Data System (ADS)

The fine-structure (FS) parameters D of a series of D3h 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 D3h symmetric septet 1,3,5-trichloro-2,4,6-trinitrenobenzene with D = -0.0957 cm-1 and E = 0 cm-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 Z1-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 |D| = 0.092 cm-1 and E = 0 cm-1. DFT calculations reveal that, unlike C2v symmetric septet trinitrenes, D3h symmetric trinitrenes have the same orientations of the spin-spin coupling tensor DSS and the spin-orbit coupling tensor DSOC and, as a result, have negative signs for both the DSS and DSOC 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 DSOC term.

Misochko, Eugenii Ya.; Akimov, Alexander V.; Masitov, Artem A.; Korchagin, Denis V.; Aldoshin, Sergei M.; Chapyshev, Sergei V.

2013-05-01

294

Heavy flavour physics from top to bottom  

SciTech Connect

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.

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

1998-02-01

295

Evidence for production of single top quarks  

Microsoft Academic Search

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

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

296

Heavy flavour physics from top to bottom  

SciTech Connect

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{bar B} mixing results. An outlook of perspectives for top and B physics in Run II starting in 1999 is also given. 38 refs., 23 figs., 8 tabs.

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

1997-01-01

297

Multi-Vector Correlations in Photofragmentation and Reactions of Polyatomic Molecules  

NASA Astrophysics Data System (ADS)

This thesis deals mainly with vector correlations in chemical and photochemical reactions. For these studies the necessary mathematical formulas involving rotation matrices are derived. They are used for the calculation of the angular distribution of products due to electric -dipole and electric-quadrupole photofragmentations. They are also used for the calculation of the intensity and alignments of two- and three-photon nonresonant transitions. During the last thirty years, much effort has been spent in the angular distribution of the diatomic photofragmentation due to (one-photon) electric-dipole transitions. There have been relatively few studies of the angular distribution of diatomic and polyatomic photofragments caused by electric-quadrupole or two-photon transitions. The reason may be the difficulty in the evaluations of the angular distributions involving the sum over magnetic quantum numbers of initial states of the fragments along with the Wigner rotational matrix elements and the integrations of the Wigner rotational matrix elements. There has been no standard and comprehensive method to solve these summations and integrations in literature. A method is therefore developed for this purpose as parts of this thesis (Chapter 2 and Chapter 3). The second parts of this thesis are devoted to two- and three-photon nonresonant excitations. Chapter 4 describes the treatment of the two-photon nonresonant excitation which extends the work of Greene and Zare to allow the initial and final states to have point-group symmetry as well as continuous-group symmetry. The results can be applied to atoms, linear molecules, symmetric-top molecules and asymmetric-top molecules. In Chapter 5, we present the algebraic angular momentum recoupling method to treat the three-photon nonresonant excitations. The expressions for the laser-induced fluorescence (LIF) intensity of a three-photon nonresonant excitations are obtained. The recurrence relations of the relevant spherical tensor operators are also obtained and some of the tensor operators are tabulated (k = 1 to 8). The general form of the reduced matrix elements of higher-order spherical tensor operators is also given. In Chapter 6, some of the computational parts of thesis that have been published including the computer programs of the 3-j, 6-j symbols, Biedenharn's triple correlation -angle functions and the bipolar harmonics are attached. These three programs are useful for future work on vector correlations.

Lai, Shan-Tao

298

A Spin-1 Top Quark Superpartner  

SciTech Connect

We construct a supersymmetric model where the left-handed top and bottom quarks are mainly the gauginos of a vector supermultiplet and hence their superpartners are spin 1. The right-handed top quark is unified with the Higgs field; the top Yukawa coupling arises from the gaugino coupling.

Cai Haiying; Cheng, H.-C.; Terning, John [Department of Physics, University of California, Davis, California 95616 (United States)

2008-10-24

299

Ownership structure and top executive turnover  

Microsoft Academic Search

We report that ownership structure significantly affects the likelihood of a change in top executive. Controlling for stock price performance, the probability of top executive turnover is negatively related to the ownership stake of officers and directors and positively related to the presence of an outside blockholder. In addition, the likehood of a change in top executive is significantly less

David J. Denis; Diane K. Denis; Atulya Sarin

1997-01-01

300

Discovery of single top quark production  

Microsoft Academic Search

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,

Dag Gillberg; for the D

2009-01-01

301

Top quark results from D0  

SciTech Connect

In this talk I will present recent preliminary results from the D0 experiment from Tevatron Run II (p{bar p} collisions at {radical}s = 1.96 TeV). The results presented in this talk include top quark pair production cross section, top quark mass, and upper limits on single top quark production.

Greenlee, H.B.; /Fermilab

2005-06-01

302

Photofragment angular momentum distributions in the molecular frame. II. Single state dissociation, multiple state interference, and nonaxial recoil in photodissociation of polyatomic molecules.  

PubMed

We present an a(q) (k)(s) polarization-parameter model to describe product angular momentum polarization from the one-photon photodissociation of polyatomic molecules in the molecular frame. We make the approximation that the final photofragment recoil direction is unique and described by the molecular frame polar coordinates (alpha,phi(i)), for which the axial recoil approximation is a special case (e.g., alpha=0). This approximation allows the separation of geometrical and dynamical factors, in particular, the expression of the experimental sensitivities to each of the a(q) (k)(s) in terms of the molecular frame polar angles (chi(i),phi(i)) of the transition dipole moment mu(i). This separation is applied to the linearly polarized photodissociation of polyatomic molecules (asymmetric, symmetric, and spherical top molecules are discussed) and to all dissociation mechanisms that satisfy our recoil approximation, including those with nonaxial recoil and multiple state interference, giving important insight into the geometrical properties of the photodissociation mechanism. For example, we demonstrate that the ratio of polarization parameters A(0) (k)(aniso)/A(0) (k)(iso)=beta (where beta is the spatial anisotropy parameter) is an indication that the dynamics can be explained by a single dissociative state. We also show that for asymmetric top photodissociation, the sensitivity to the a(1) (k)(s) parameters, which can arise either from single-surface or multiple-surface interference mechanisms, is nonzero only for components of the transition dipole moments within the v-d plane of the recoil frame. PMID:20550400

Rakitzis, T Peter; Alexander, Andrew J

2010-06-14

303

Rotationally symmetric operators for surface interpolation  

SciTech Connect

The use of rotationally symmetric operators in vision is reviewed and conditions for rotational symmetry are derived for linear and quadratic forms in the first and second partial directional derivatives of a function f(x,y). Surface interpolation is considered to be the process of computing the most conservative solution consistent with boundary conditions. The 'most conservative' solution is modelled using the calculus of variations to find the minimum function that satisfies a given performance index. To guarantee the existence of a minimum function, Grimson has recently suggested that the performance index should be a seminorm. It is shown that all quadratic forms in the second partial derivatives of the surface satisfy this criterion. The seminorms that are, in addition, rotationally symmetric form a vector space whose basis is the square Laplacian and the quadratic variation. Whereas both seminorms give rise to the same Euler condition in the interior, the quadratic variation offers the tighter constraint at the boundary and is to be preferred for surface interpolation.

Brady, M.; Horn, B.K.P.

1982-01-01

304

PT-symmetric deformations of integrable models.  

PubMed

We review recent results on new physical models constructed as PT-symmetrical deformations or extensions of different types of integrable models. We present non-Hermitian versions of quantum spin chains, multi-particle systems of Calogero-Moser-Sutherland type and nonlinear integrable field equations of Korteweg-de Vries type. The quantum spin chain discussed is related to the first example in the series of the non-unitary models of minimal conformal field theories. For the Calogero-Moser-Sutherland models, we provide three alternative deformations: a complex extension for models related to all types of Coxeter/Weyl groups; models describing the evolution of poles in constrained real-valued field equations of nonlinear integrable systems; and genuine deformations based on antilinearly invariant deformed root systems. Deformations of complex nonlinear integrable field equations of Korteweg-de Vries type are studied with regard to different kinds of PT-symmetrical scenarios. A reduction to simple complex quantum mechanical models currently under discussion is presented. PMID:23509376

Fring, Andreas

2013-03-18

305

Table-top job analysis  

SciTech Connect

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.

Not Available

1994-12-01

306

MHD Integrated Topping Cycle Project  

SciTech Connect

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.

Not Available

1992-07-01

307

Magnetic control of a meta-molecule.  

PubMed

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

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

308

MEtop – a top FCNC event generator  

NASA Astrophysics Data System (ADS)

In this work we present a new Monte Carlo generator for Direct top and Single top production via flavour-changing neutral currents (FCNC). This new tool calculates the cross section and generates events with Next-to-Leading order precision for the Direct top process and Leading-Order precision for all other FCNC single top processes. A set of independent dimension six FCNC operators has been implemented – including four-fermion operators – where at least one top-quark is present in the interaction.

Coimbra, Rita; Onofre, António; Santos, Rui; Won, Miguel

2013-07-01

309

Measurements of top quark properties at CDF  

SciTech Connect

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.

Kraan, Aafke C.; /Pennsylvania U.

2006-11-01

310

Top Quark Mass Measurements at the Tevatron  

SciTech Connect

We report the latest results on the top-quark mass and on the top-antitop mass difference from the CDF and D0 collaborations using data collected at the Fermilab Tevatron p{bar p} collider at {radical}s = 1.96 TeV. We discuss general issues in top-quark mass measurements and present new results from direct measurements and from top-pair production cross-section. We also report new results on the top-antitop mass difference.

Ye, Zhenyu; /Fermilab

2011-07-01

311

Top Quark Physics at the Tevatron  

SciTech Connect

The authors review the field of top-quark physics with an emphasis on experimental techniques. The role of the top quark in the Standard Model of particle physics is summarized and the basic phenomenology of top-quark production and decay is introduced. They discuss how contributions from physics beyond the Standard model could affect the top-quark properties or event samples. The many measurements made at the Fermilab Tevatron, which test the Standard model predictions or probe for direct evidence of new physics using the top-quark event samples, are reviewed here.

Deliot, Frederic; /DAPNIA, Saclay; Glenzinski, Douglas A.; /Fermilab

2010-10-01

312

Probing top quark electromagnetic dipole moments in single-top-plus-photon production  

NASA Astrophysics Data System (ADS)

The production of a single top quark in association with an isolated photon probes the electromagnetic coupling structure of the top quark. We investigate the sensitivity of kinematical distributions at the LHC in single-top-plus-photon production in view of a detection of anomalous electric and magnetic dipole moments of the top quark.

Fael, M.; Gehrmann, T.

2013-08-01

313

MHD Integrated Topping Cycle Project  

SciTech Connect

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.

Not Available

1992-01-01

314

LHC limits on the top-Higgs in models with strong top-quark dynamics  

SciTech Connect

LHC searches for the standard model Higgs boson in WW or ZZ decay modes place strong constraints on the top-Higgs state predicted in many models with new dynamics preferentially affecting top quarks. Such a state couples strongly to top quarks, and is therefore produced through gluon fusion at a rate enhanced relative to the rate for the standard model Higgs boson. A top-Higgs state with mass less than 300 GeV is excluded at 95% C.L. if the associated top-pion has a mass of 150 GeV, and the constraint is even stronger if the mass of the top-pion state exceeds the top-quark mass or if the top-pion decay constant is a substantial fraction of the weak scale. These results have significant implications for theories with strong top dynamics, such as topcolor-assisted technicolor, top-seesaw models, and certain Higgsless models.

Chivukula, R. Sekhar; Simmons, Elizabeth H.; Coleppa, Baradhwaj; Logan, Heather E.; Martin, Adam [Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); Ottawa-Carleton Institute for Physics, Carleton University, Ottawa, Ontario K1S 5B6 (Canada); Theoretical Physics Department, Fermilab, Batavia, Illinois 60510 (United States)

2011-11-01

315

Operational multipartite entanglement classes for symmetric photonic qubit states  

SciTech Connect

We present experimental schemes that allow us to study the entanglement classes of all symmetric states in multiqubit photonic systems. We compare the efficiency of the proposed schemes and highlight the relation between the entanglement properties of symmetric Dicke states and a recently proposed entanglement scheme for atoms. In analogy to the latter, we obtain a one-to-one correspondence between well-defined sets of experimental parameters and multiqubit entanglement classes inside the symmetric subspace of the photonic system.

Kiesel, N.; Wieczorek, W.; Weinfurter, H. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Department fuer Physik, Ludwig-Maximilians-Universitaet, D-80797 Garching (Germany); Krins, S.; Bastin, T. [Institut de Physique Nucleaire, Atomique et de Spectroscopie, Universite de Liege, 4000 Liege (Belgium); Solano, E. [Departamento de Quimica Fisica, Universidad del Pais Vasco/Euskal Herriko Unibertsitatea, Apdo. 644, 48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, Alameda Urquijo 36, 48011 Bilbao (Spain)

2010-03-15

316

Fabrication Examples of Non-rotationally Symmetric Optical Elements  

Microsoft Academic Search

Two examples of a fabrication of non-rotationally symmetric optical elements are presented here, with a particular attention given to the techniques chosen for the process. Abrasive Grinding is mentioned briefly as the technique which originated many of the early applications of non-symmetric optics, followed by Fast Tool Servo turning and Diamond Milling. Metrology tools for non-symmetric optics, or lack thereof,

J. J. Mader; D. M. Combs; N. E. Claytor; O. M. Lechuga

317

Symmetric instability in the Gulf Stream  

NASA Astrophysics Data System (ADS)

Analyses of wintertime surveys of the Gulf Stream (GS) conducted as part of the CLIvar MOde water Dynamic Experiment (CLIMODE) reveal that water with negative potential vorticity (PV) is commonly found within the surface boundary layer (SBL) of the current. The lowest values of PV are found within the North Wall of the GS on the isopycnal layer occupied by Eighteen Degree Water, suggesting that processes within the GS may contribute to the formation of this low-PV water mass. In spite of large heat loss, the generation of negative PV was primarily attributable to cross-front advection of dense water over light by Ekman flow driven by winds with a down-front component. Beneath a critical depth, the SBL was stably stratified yet the PV remained negative due to the strong baroclinicity of the current, suggesting that the flow was symmetrically unstable. A large eddy simulation configured with forcing and flow parameters based on the observations confirms that the observed structure of the SBL is consistent with the dynamics of symmetric instability (SI) forced by wind and surface cooling. The simulation shows that both strong turbulence and vertical gradients in density, momentum, and tracers coexist in the SBL of symmetrically unstable fronts. SI is a shear instability that draws its energy from geostrophic flows. A parameterization for the rate of kinetic energy (KE) extraction by SI applied to the observations suggests that SI could result in a net dissipation of 33 mW m-2 and 1 mW m-2 for surveys with strong and weak fronts, respectively. The surveys also showed signs of baroclinic instability (BCI) in the SBL, namely thermally direct vertical circulations that advect biomass and PV. The vertical circulation was inferred using the omega equation and used to estimate the rate of release of available potential energy (APE) by BCI. The rate of APE release was found to be comparable in magnitude to the net dissipation associated with SI. This result points to an energy pathway where the GS's reservoir of APE is drained by BCI, converted to KE, and then dissipated by SI and its secondary instabilities. Similar dynamics are likely to be found at other strong fronts forced by winds and/or cooling and could play an important role in the energy balance of the ocean circulation.

Thomas, Leif N.; Taylor, John R.; Ferrari, Raffaele; Joyce, Terrence M.

2013-07-01

318

Permutationally invariant polynomial basis for molecular energy surface fitting via monomial symmetrization.  

SciTech Connect

We describe a procedure to develop a fitting basis for molecular potential energy surfaces (PESs) that is invariant with respect to permutation of like atoms. The method is based on a straightforward symmetrization of a primitive monomial basis and illustrated for several classes of molecules. A numerically efficient method to evaluate the resulting expression for the PES is also described. The fitting basis is used to obtain a new PES for H{sub 3}O{sup +} based on roughly 62000 ab initio energies.

Xie, Z.; Bowman, J. M.; Mathematics and Computer Science; Emory Univ.

2010-01-01

319

Covariant approach for perturbations of rotationally symmetric spacetimes  

SciTech Connect

We present a covariant decomposition of Einstein's field equations which is particularly suitable for perturbations of spherically symmetric - and general locally rotationally symmetric - spacetimes. Based upon the utility of the 1+3 covariant approach to perturbation theory in cosmology, the semi-tetrad, 1+1+2 approach presented here should be useful for analyzing perturbations of a variety of systems in a covariant and gauge-invariant manner. Such applications range from stellar objects to cosmological models such as the spherically symmetric Lemaitre-Tolman-Bondi solutions or the class of locally rotationally symmetric Bianchi models.

Clarkson, Chris [Cosmology and Gravity Group, Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, Cape Town (South Africa)

2007-11-15

320

Patterns of energy levels and spectra for polyatomic molecules  

SciTech Connect

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.

Harter, W.G.

1983-01-01

321

Greenhouse Gas Molecules  

NSDL National Science Digital Library

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.

College, Beloit

322

Geometric inequalities for axially symmetric black holes  

NASA Astrophysics Data System (ADS)

A geometric inequality in general relativity relates quantities that have both a physical interpretation and a geometrical definition. It is well known that the parameters that characterize the Kerr-Newman black hole satisfy several important geometric inequalities. Remarkably enough, some of these inequalities also hold for dynamical black holes. This kind of inequalities play an important role in the characterization of the gravitational collapse; they are closely related with the cosmic censorship conjecture. Axially symmetric black holes are the natural candidates to study these inequalities because the quasi-local angular momentum is well defined for them. We review recent results in this subject and we also describe the main ideas behind the proofs. Finally, a list of relevant open problems is presented.

Dain, Sergio

2012-04-01

323

Lovelock black holes with maximally symmetric horizons  

NASA Astrophysics Data System (ADS)

We investigate some properties of n( >= 4)-dimensional spacetimes having symmetries corresponding to the isometries of an (n - 2)-dimensional maximally symmetric space in Lovelock gravity under the null or dominant energy condition. The well-posedness of the generalized Misner-Sharp quasi-local mass proposed in the past study is shown. Using this quasi-local mass, we clarify the basic properties of the dynamical black holes defined by a future outer trapping horizon under certain assumptions on the Lovelock coupling constants. The C2 vacuum solutions are classified into four types: (i) Schwarzschild-Tangherlini-type solution; (ii) Nariai-type solution; (iii) special degenerate vacuum solution; and (iv) exceptional vacuum solution. The conditions for the realization of the last two solutions are clarified. The Schwarzschild-Tangherlini-type solution is studied in detail. We prove the first law of black-hole thermodynamics and present the expressions for the heat capacity and the free energy.

Maeda, Hideki; Willison, Steven; Ray, Sourya

2011-08-01

324

A Symmetric Bipolar Nebula Around MWC 922  

NASA Astrophysics Data System (ADS)

We report regular and symmetric structure around dust-enshrouded Be star MWC 922 with infrared imaging. Biconical lobes that appear nearly square in aspect, forming this “Red Square” nebula, are crossed by a series of rungs that terminate in bright knots or “vortices,” while an equatorial dark band crossing the core delimits twin hyperbolic arcs. The intricate yet cleanly constructed forms that comprise the skeleton of the object argue for minimal perturbation from global turbulent or chaotic effects. We also report the presence of a linear comb structure, which may arise from optically projected shadows of a periodic feature in the inner regions, such as corrugations in the rim of a circumstellar disk. The sequence of nested polar rings draws comparison with the triple-ring system seen around the only naked-eye supernova in recent history: SN1987A.

Tuthill, P. G.; Lloyd, J. P.

2007-04-01

325

Canonical quantization of static spherically symmetric geometries  

NASA Astrophysics Data System (ADS)

The conditional symmetries of the reduced Einstein–Hilbert action emerging from a static, spherically symmetric geometry are used as supplementary conditions on the wave function. Based on their integrability conditions, only one of the three existing symmetries can be consistently imposed, while the unique Casimir invariant, being the product of the remaining two symmetries, is calculated as the only possible second condition on the wave function. This quadratic integral of motion is identified with the reparametrization generator, as an implication of the uniqueness of the dynamical evolution, by fixing a suitable parametrization of the r-lapse function. In this parametrization, the determinant of the supermetric plays the role of the mesure. The combined Wheeler – DeWitt and linear conditional symmetry equations are analytically solved. The solutions obtained depend on the product of the two "scale factors".

Christodoulakis, T.; Dimakis, N.; Terzis, P. A.; Doulis, G.; Grammenos, Th; Melas, E.; Spanou, A.

2013-08-01

326

From symmetric glycerol derivatives to dissymmetric chlorohydrins.  

PubMed

The anticipated worldwide increase in biodiesel production will result in an accumulation of glycerol for which there are insufficient conventional uses. The surplus of this by-product has increased rapidly during the last decade, prompting a search for new glycerol applications. We describe here the synthesis of dissymmetric chlorohydrin esters from symmetric 1,3-dichloro-2-propyl esters obtained from glycerol. We studied the influence of two solvents: 1,4-dioxane and 1-butanol and two bases: sodium carbonate and 1-butylimidazole, on the synthesis of dissymmetric chlorohydrin esters. In addition, we studied the influence of other bases (potassium and lithium carbonates) in the reaction using 1,4-dioxane as the solvent. The highest yield was obtained using 1,4-dioxane and sodium carbonate. PMID:21368718

Solarte, Carmen; Escribà, Marc; Eras, Jordi; Villorbina, Gemma; Canela, Ramon; Balcells, Mercè

2011-03-02

327

mathcal{CPT}-Symmetric Discrete Square Well  

NASA Astrophysics Data System (ADS)

In an addendum to the recent systematic Hermitization of certain N by N matrix Hamiltonians H ( N)( ?) (Znojil in J. Math. Phys. 50:122105, 2009) we propose an amendment H ( N)( ?, ?) of the model. The gain is threefold. Firstly, the updated model acquires a natural mathematical meaning of Runge-Kutta approximant to a differential mathcal{PT}-symmetric square well in which mathcal{P} is parity. Secondly, the appeal of the model in physics is enhanced since the related operator mathcal{C} of the so called "charge" (the requirement of observability of which defines the most popular Bender's metric ?=mathcal{PC}) becomes also obtainable (and is constructed here) in an elementary antidiagonal matrix form at all N. Last but not least, the original phenomenological energy spectrum is not changed so that the domain of its reality (i.e., the interval of admissible couplings ??(-1,1)) remains the same.

Znojil, Miloslav; Tater, Miloš

2011-04-01

328

Circularly symmetric light scattering from nanoplasmonic spirals.  

PubMed

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

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

2011-04-05

329

VACUUM calculation in azimuthally symmetric geometry  

SciTech Connect

A robustly accurate and effective method is presented to solve Laplace`s equation in general azimuthally symmetric geometry for the magnetic scalar potential in the region surrounding a plasma discharge which may or may not contain external conducting shells. These shells can be topologically toroidal or spherical, and may have toroidal gaps in them. The solution is incorporated into the various MHD stability codes either through the volume integrated perturbed magnetic energy in the vacuum region or through the continuity requirements for the normal component of the perturbed magnetic field and the total perturbed pressure across the unperturbed plasma-vacuum boundary. The method is based upon using Green`s second identity and the method of collocation. As useful byproducts, the eddy currents and the simulation of Mirnov loop measurements are calculated.

Chance, M.S.

1996-11-01

330

Nonlinear dynamics in PT-symmetric lattices  

NASA Astrophysics Data System (ADS)

We consider nonlinear dynamics in a finite parity-time-symmetric chain of the discrete nonlinear Schrödinger (dNLS) type. For arbitrary values of the gain and loss parameter, we prove that the solutions of the dNLS equation do not blow up in a finite time but nevertheless, there exist trajectories starting with large initial data that grow exponentially fast for larger times with a rate that is rigorously identified. In the range of the gain and loss parameter, where the zero equilibrium state is neutrally stable, we prove that the trajectories starting with small initial data remain bounded for all times. Numerical computations illustrate these analytical results for dimers and quadrimers.

Kevrekidis, Panayotis G.; Pelinovsky, Dmitry E.; Y Tyugin, Dmitry

2013-09-01

331

Symmetric Lipofibromatous Hamartoma Affecting Digital Nerves  

PubMed Central

Lipofibromatous hamartoma of the nerve is a benign tumor, which affects the major nerves and their branches in the human body. It is often found in the median nerve of the hand and is commonly associated with macrodactyly, but it is rarely found in the digital nerves at the peripheral level. This tumor is often found in young adults and may go through a self-limiting course. However, operation is indicated when the tumor size is large or when the associated nerve compressive symptoms are present. We have experienced a rare case of lipofibromatous hamartoma that symmetrically involved the volar digital nerves of both index fingers on the ulnar side. With the aid of a microscope, we dissected and removed the tumor as much as possible without sacrificing the nerve. No sensory change occurred in both fingers and no sign of recurrence was observed upon follow-up.

Jung, Sung-No; Yim, Youngmin

2005-01-01

332

Nucleic acid molecule  

US Patent & Trademark Office Database

The invention relates to an isolated nucleic acid molecule encoding a polypeptide capable of producing a triterpenoid hydrocarbon. The invention also relates to the encoded polypeptide, a vector comprising the nucleic acid molecule, a recombinant non-human organism comprising the nucleic acid molecule, and to methods of producing a triterpenoid hydrocarbon or an intermediate of biofuel using the nucleic acid molecule, polypeptide or recombinant organism.

Ball; Andrew (Bedford Park, AU); Moore; Robert (Bedford Park, AU); Knowles; Gregory (Bedford Park, AU); Qin; Jian (Bedford Park, AU)

2011-10-11

333

Top-Down and Free  

NASA Astrophysics Data System (ADS)

The ``Top-Down Physics'' (TDP) project is aimed at unifying material traditionally covered in Classical Mechanics, and Electricity & Magnetism, as well as elements of Quantum Mechanics and Statistical Dynamics at the undergraduate level. The main computational platforms for the student projects have been LaTeX, MAPLE and JAVA. Relevant theoretic, algorithmic and technical (software) elements are introduced as needed to simulate laboratory-style experiments carried out in class. Ideally, solutions developed by ``senior'' students can be ``beta- tested'' during classroom and laboratory demonstrations to lower- level students. In this way, the curriculum naturally ``folds'' onto itself. Current efforts include the use of the Open Source Physics and Maxima to develop a platform-independent (and free) framework for the TDP framework.

Schillaci, Michael

2007-11-01

334

MHD Integrated Topping Cycle Project  

SciTech Connect

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.

Not Available

1992-07-01

335

Topping up experiments at SRRC  

SciTech Connect

In an operation of a synchrotron radiation facility, it is very desirable to be able to provide beam with almost constant intensity. This has considerable advantage in terms of calibration and normalization of detectors, heat load of optical components,and the duration of data taking time. To achieve that goal, the topping up mode injection has been tested at SRRC. The experiment was performed to fill automatically the stored beam current up to 200 mA whenever it was decreased to a present low limit value. The following items were examined: reproducibility of the bunch train structure of the injected beam, stability of the storage ring pulsed injection magnets, injection startup and bucket address system. Effects on the stored beam stability will be studied and methods to minimize disruption to research program during injection time will be investigated.

Ueng, T.S.; Hsu, K.T.; Chen, J.; Lin, K.K. [Synchrotron Radiation Research Center, Hsinchu (Taiwan, Province of China); Weng, W.T. [Synchrotron Radiation Research Center, Hsinchu (Taiwan, Province of China)]|[Brookhaven National Lab., Upton, NY (United States)

1996-10-01

336

Intracellular delivery of top-down fabricated tunable nano-plasmonic resonators  

NASA Astrophysics Data System (ADS)

Engineered plasmonic structures fabricated using top-down technologies have demonstrated huge enhancements in the optical response of molecules, including Raman scattering. However, providing a sufficient number of such top-down fabricated nanostructures in solution has been a nontrivial task which has limited their potential in intracellular applications. Here we report the development of a protocol for the intracellular delivery of tunable nanoplasmonic resonators fabricated via scalable top-down techniques. This offers excellent possibilities towards the real-time parallel optical detection of intracellular molecular events.Engineered plasmonic structures fabricated using top-down technologies have demonstrated huge enhancements in the optical response of molecules, including Raman scattering. However, providing a sufficient number of such top-down fabricated nanostructures in solution has been a nontrivial task which has limited their potential in intracellular applications. Here we report the development of a protocol for the intracellular delivery of tunable nanoplasmonic resonators fabricated via scalable top-down techniques. This offers excellent possibilities towards the real-time parallel optical detection of intracellular molecular events. Electronic supplementary information (ESI) available: Details of fabrication methods are described. See DOI: 10.1039/c3nr02910g

Ota, Sadao; Wang, Sheng; Ryu, Jongeun; Wang, Yuan; Chen, Yong; Zhang, Xiang

2013-10-01

337

Structural tailoring effects on the magnetic behavior of symmetric and asymmetric cubane-type Ni complexes.  

PubMed

Using two kinds of carboxylate ligands with small but significant differences in steric size, symmetric and asymmetric Fe(II) and Ni(II) cubanes have been synthesized in a controlled fashion. Fast sweeping pulsed field measurements showed magnetization hysteresis loops for two cubane-type molecular complexes, [Ni4(?-OMe)4(O2CAr(4F-Ph))4(HOMe)8] and [Ni4(?-OMe)4(O2CAr(Tol))4(HOMe)6], thus suggesting single-molecule magnet behavior. To differentiate the magnetic properties between the symmetric and asymmetric cubanes, detailed electron paramagnetic resonance (EPR) measurements were performed. From the EPR data, taken at various frequencies and temperatures, zero-field splitting parameters D, E, and other higher-order parameters for both cubane samples were extracted. Compared to the symmetric Ni-cubane, the asymmetric one shows an increase in the D and E values by about 20%, thereby suggesting structural engineering effects on the magnetic properties. By using the magnetic parameters determined by EPR, a static magnetization curve at 2?K and a temperature dependence of the magnetic susceptibility were simulated. A good agreement between theoretical and experimental data confirms the validity of the values obtained from EPR measurements. PMID:23509044

Ponomaryov, Alexey N; Kim, Namseok; Hwang, Jaewon; Nojiri, Hiroyuki; van Tol, Johan; Ozarowski, Andrew; Park, Jena; Jang, Zeehoon; Suh, Byoungjin; Yoon, Sungho; Choi, Kwang-Yong

2013-03-18

338

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

Microsoft Academic Search

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

R. O. Adlof; G. R. List

2008-01-01

339

Trapping polar molecules in an ac trap  

SciTech Connect

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}.

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

340

Entanglement and chaos in the kicked top  

NASA Astrophysics Data System (ADS)

The standard kicked top involves a periodically kicked angular momentum. By considering this angular momentum as a collection of entangled spins, we compute the bipartite entanglement dynamics as a function of the dynamics of the classical counterpart. Our numerical results indicate that the entanglement of the quantum top depends on the specific details of the dynamics of the classical top rather than depending universally on the global properties of the classical regime. These results are grounded on linking the entanglement rate to averages involving the classical angular momentum, thereby explaining why regular dynamics can entangle as efficiently as the classically chaotic regime. The findings are in line with previous results obtained with a two-particle top model, and we show here that the standard kicked top can be obtained as a limiting case of the two-particle top.

Lombardi, M.; Matzkin, A.

2011-01-01

341

REVIEW The Use and Misuse of Conditional Symmetric Instability  

Microsoft Academic Search

A commonly employed explanation for single- and multiple-banded clouds and precipitation in the extratropics is slantwise convection due to the release of moist symmetric instability (MSI), of which one type is conditional symmetric instability (CSI). This article presents a review of CSI with the intent of synthesizing the results from previous observational, theoretical, and modeling studies. This review contends that

DAVID M. SCHULTZ; PHILIP N. SCHUMACHER

342

Constraints on the uncertainties of entangled symmetric qubits  

NASA Astrophysics Data System (ADS)

We derive necessary and sufficient inseparability conditions imposed on the variance matrix of symmetric qubits. These constraints are identified by examining a structural parallelism between continuous variable states and two-qubit states. Pairwise entangled symmetric multiqubit states are shown here to obey these constraints. We also bring out an elegant local invariant structure exhibited by our constraints.

Usha Devi, A. R.; Uma, M. S.; Prabhu, R.; Rajagopal, A. K.

2007-04-01

343

Lipoblastomatosis appearing as an unusual symmetric upper lip deformity.  

PubMed

We report an unusual case of a bilateral, symmetric upper lip deformity. The submucosal tissue of the resected redundant portion of the lip was occupied by a mass that was diagnosed histopathologically as lipoblastomatosis. Differential diagnoses of lesions with symmetric upper lip deformity and current controversy regarding the surgical treatment are discussed here. PMID:21784719

Morioka, Daichi; Amikura, Yoshiyasu

2011-07-23

344

Vacuum spherically symmetric solutions in f( T) gravity  

NASA Astrophysics Data System (ADS)

Spherically symmetric static vacuum solutions have been built in f( T) models of gravity theory. We apply some conditions on the metric components; then new vacuum spherically symmetric solutions are obtained. Also, by extracting metric coefficients we determine the analytical form of f( T).

Atazadeh, K.; Mousavi, Misha

2013-01-01

345

Minimum-error discrimination between symmetric mixed quantum states  

SciTech Connect

We provide a solution of finding optimal measurement strategy for distinguishing between symmetric mixed quantum states. It is assumed that the matrix elements of at least one of the symmetric quantum states are all real and non-negative in the basis of the eigenstates of the symmetry operator.

Chou, C.-L. [Department of Physics, Chung-Yuan Christian University, Taoyuan 32023, Taiwan (China); Hsu, L.Y. [Physics Division, National Center of Theoretical Science, Hsinchu 30055, Taiwan (China)

2003-10-01

346

Symmetric profile beams from waveguides with asymmetric grating couplers.  

PubMed

An accurate method to analyze integrated optics waveguides with a grating is used to design diffractive gratings. A novel approach to produce symmetric diffracted beams is proposed. In this approach, we vary the grating duty cycle along the propagation direction. We demonstrate that this method results in symmetrical diffracted beam profiles. PMID:18253245

Touam, T; Najafi, S I

1997-04-20

347

Generalized Symmetric Nonextensive Thermostatistics and q-MODIFIED Structures  

NASA Astrophysics Data System (ADS)

We formulate a convenient generalization of the q-expectation value, based on the analogy of the symmetric quantum groups and q-calculus, and show that the q? q-1 symmetric nonextensive entropy preserves all of the mathematical structure of thermodynamics just as in the case of nonsymmetric. Tsallis statistics. Basic propreties and analogies with quantum groups are discussed.

Lavagno, A.; Swamy, P. Narayana

348

Horospherical Cauchy-Radon transform on compact symmetric spaces  

Microsoft Academic Search

Harmonic analysis on noncompact Riemannian symmetric spaces is in a sense equivalent to the theory of the horospherical transform. There are no horospheres on compact symmetric spaces, but we define a complex version of horospherical transform which plays a similar role for the harmonic analysis on them.

Simon Gindikin

2005-01-01

349

Parity-Based Concurrent Error Detection in Symmetric Block Ciphers  

Microsoft Academic Search

Deliberate injection of faults into cryptographic devices is an effective cryptanalysis technique against symmetric and asymmetric encryption. We will describe a general concurrent error detection (CED) approach against such attacks on symmetric block ciphers using CS-cipher as an example. The proposed CED compares a carefully modified parity of the input plain text with that of the output cipher text. An

Ramesh Karri; Grigori Kuznetsov; Michael Goessel

2003-01-01

350

Stability of Trilateral Forces: II, Large Symmetric Force  

SciTech Connect

For large symmetric offensive forces, as for small, at few weapons per missile all forces are reserved, costs are constant, and configurations are stable. At many weapons permissile, no weapons are reserved, first strike costs decrease, fractionation is attractive, and stability degrades. These results a due to symmetries that would not be degraded by additional symmetric opponents.

Canavan, G.H.

1998-09-17

351

Directed cyclic Hamiltonian cycle systems of the complete symmetric digraph  

Microsoft Academic Search

In this paper, we prove that directed cyclic hamiltonian cycle systems of the complete symmetric digraph, K n, exist if and only if n 2 (mod4) and n 6= 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-independent digons, (Kn I) , exist

Heather Jordon; Joy Morris

2009-01-01

352

Bunch-Kaufman Factorization for Real Symmetric Indefinite Banded Matrices.  

National Technical Information Service (NTIS)

The Bunch-Kaufman algorithm for factoring symmetric indefinite matrices has been rejected for banded matrices because it destroys the banded structure of the matrix. Herein, it is shown that for a subclass of real symmetric matrices which arise in solving...

M. L. Patrick M. T. Jones

1989-01-01

353

Hierarchical Shape Description Via the Multiresolution Symmetric Axis Transform  

Microsoft Academic Search

A method is proposed that produces a shape description in the form of a hierarchy by scale of simple symmetric axis sequences. An axis segment that is a child of another has smaller scale and is seen as a branch of its parent. The scale value and parent-child relationship are induced by following the symmetric axis under successive reduction of

Stephen M. Pizer; William R. Oliver; Sandra H. Bloomberg

1987-01-01

354

Symmetrical decorations enhance the attractiveness of faces and abstract designs  

Microsoft Academic Search

In humans and several other species, face and body symmetry have been found to enhance physical attractiveness. A proposed explanation is that symmetry is a phenotypic indicator of biological fitness. Throughout the world, symmetrical designs also are a common feature in face and body painting and the decorative arts. The implication is that symmetrical designs might provide an additional way

Rodrigo Andrés Cárdenas; Lauren Julius Harris

2006-01-01

355

Top quark measurements at the Tevatron  

SciTech Connect

The authors present top physics results from the CDF and D0 collaborations. The data were collected at the Fermilab Tevatron over the years 1992--1995 and correspond to approximately 110 pb{sup {minus}1} of p{anti p} collisions. Both experiments present determination of the t{anti t} production cross section using a variety of top decay channels, and refined measurements of the top mass.

Kestenbaum, D.S.; CDF Collaboration; D0 Collaboration

1997-01-01

356

TOP500 Supercomputers for June 2005  

SciTech Connect

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.

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

2005-06-22

357

TOP500 Supercomputers for June 2004  

SciTech Connect

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.

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

2004-06-23

358

Top quark properties at the Tevatron  

SciTech Connect

Recent preliminary results on top quark properties from the CDF and D0 collaborations at the Fermilab Tevatron are described. These analyses include: measurements of the ratio B(t {yields} Wb)/B(t {yields} Wq) and of B(t {yields} {tau}vq), search for anomalous kinematics, studies on the helicity of W bosons originating from top quark decays, spin correlations between top quark pairs, and searches for t{bar t} resonance production in models beyond the standard model.

Garcia-Bellido, Aran; /Washington U., Seattle

2004-11-01

359

Current through single conjugated molecules: Calculations versus measurements  

NASA Astrophysics Data System (ADS)

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.

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

2008-07-01

360

Crystal Engineering of Tetrahedral `Nano Molecules' Constructed by POSS Cages  

NASA Astrophysics Data System (ADS)

Functional hybrid materials provide us a powerful approach to acquire novel hierarchical structures and exceptional properties. Designed nanoparticle building blocks with specific interactions can self-assemble into targeted ordered structures with intriguing shapes, sizes and functionalities. Classical high symmetric `nano atoms', Polyhedral Oligomeric Silsesquioxane (POSS) can be utilized to construct `nano molecules' with different symmetry, which can further act as novel nanoparticle building blocks. Very interesting rigid tetrahedral `nano molecules' covalent linking four POSS cages were synthesized. Their close packing structures in crystal were determined by transmission electron microscopy (TEM) and wide angle X-ray diffraction (WAXD).

Huang, Mingjun; Mei, Shan; Cheng, Stephen

2013-03-01

361

Single Top Quarks at the Tevatron  

SciTech Connect

After many years searching for electroweak production of top quarks, the Tevatron collider experiments have now moved from obtaining first evidence for single top quark production to an impressive array of measurements that test the standard model in several directions. This paper describes measurements of the single top quark cross sections, limits set on the CKM matrix element |Vtb|, searches for production of single top quarks produced via flavor-changing neutral currents and from heavy W-prime and H+ boson resonances, and studies of anomalous Wtb couplings. It concludes with projections for future expected significance as the analyzed datasets grow.

Heinson, Ann P.; /UC, Riverside

2008-09-01

362

A natural symmetrization for the plummer potential  

NASA Astrophysics Data System (ADS)

We propose a symmetrized form of the softened gravitational potential which is a natural extension of the Plummer potential. The gravitational potential at the position of particle i( xi, yi, zi), induced by particle j at ( xj, yj, zj), is given by: ?ij=-{Gmj}/{|rij2+?i2+?j2|}, where G is the gravitational constant, mj is the mass of particle j, rij = ?( xi - xj) 2 + ( yi - yj) 2 + ( zi - zj) 2? 1/2 and ?i and ?j are the gravitational softening lengths of particles i and j, respectively. This form is formally an extension of the Newtonian potential to five dimensions. The derivative of this equation in the x, y, and z directions correspond to the gravitational accelerations in these directions and they are always symmetric between two particles. When one applies this potential to a group of particles with different softening lengths, as in the case with a tree code, an averaged gravitational softening length for the group can be used. We find that the most suitable averaged softening length for a group of particles is =?jNmj?j2/M, where M=?jNmj and N are the mass and number of all particles in the group, respectively. The leading error related to the softening length is O?j?rj??j2/rij3, where ?rj is the distance between particle j and the center of mass of the group and ??j2=?j2-. Using this averaged gravitational softening length with the tree method, one can use a single tree to evaluate the gravitational forces for a system of particles with a wide variety of gravitational softening lengths. Consequently, this will reduce the calculation cost of the gravitational force for such a system with different softenings without the need for complicated forms of softening. We present the result of simple numerical tests. We found that our modification of the Plummer potential works well.

Saitoh, Takayuki R.; Makino, Junichiro

2012-02-01

363

Lyndon Words and Transition Matrices between Elementary, Homogeneous and Monomial Symmetric Functions  

Microsoft Academic Search

Let h, e ,a ndm denote the homogeneous symmetric function, the elementary symmetric function and the monomial symmetric function associated with the par- tition respectively. We give combinatorial interpretations for the coecients that arise in expanding m in terms of homogeneous symmetric functions and the ele- mentary symmetric functions. Such coecients are interpreted in terms of certain classes of bi-brick

Andrius Kulikauskas; Jeffrey B. Remmel

2006-01-01

364

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

SciTech Connect

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.

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

2009-10-16

365

The TOP-IMPLART project  

NASA Astrophysics Data System (ADS)

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.

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

366

Top-of-Rail lubricant  

SciTech Connect

Analysis of the volatile and semivolatile fractions collected after use of the TOR lubricant indicated that other than contaminants in the collection laboratory, no compounds on the EPA's Target Compound Lists (Tables 2 and 5) were detected in these fractions. The data of these qualitative analyses, given in the various tables in the text, indicate only the relative amounts of the tentatively identified compounds. The authors recommend that quantitative analysis be performed on the volatile and semivolatile fractions to allow confirmation of the tentatively identified compounds and to obtain absolute amounts of the detected compounds. Additionally, the semivolatile fraction should be analyzed by liquid chromatography/mass spectrometry to identify compounds that are not chromatographable under the temperature program used for determination of semivolatile compounds. Introducing the top-of-rail (TOR) lubricant into the wheel/rail interface results in a reduction of almost 60% of lateral friction force over the forces encountered under dry conditions. This reveals good potential for energy savings, as well as wear reduction, for railroad companies. In TOR lubrication, an increase in the angle of attack and axle load results in increased lateral friction and rate of lubricant consumption. The most efficient TOR lubricant quantity to be used in the wheel/rail interface must be calculated precisely according to the number of cars, axle loads, train speed, and angle of attack.

Alzoubi, M. F.; Fenske, G. R.; Erck, R. A.; Boparai, A. S.

2000-07-14

367

MHD Integrated Topping Cycle Project  

SciTech Connect

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.

Not Available

1992-02-01

368

Skyrmions and vector mesons: a symmetric approach  

SciTech Connect

We propose an extension of the effective, low-energy chiral Lagrangian known as the Skyrme model, to one formulated by a non-linear sigma model generalized to include vector mesons in a symmetric way. The model is based on chiral SU(6) x SU(6) symmetry spontaneously broken to static SU(6). The rho and other vector mesons are dormant Goldstone bosons since they are in the same SU(6) multiplet as the pion and other pseudoscalars. Hence the manifold of our generalized non-linear sigma model is the coset space (SU(6) x SU(6))/Su(6). Relativistic effects, via a spin-dependent mass term, break the static SU(6) and give the vectors a mass. The model can then be fully relativistic and covariant. The lowest-lying Skyrmion in this model is the whole baryonic 56-plet, which splits into the octet and decuplet in the presence of relativistic SU(6)-breaking. Due to the built-in SU(6) and the presence of vector mesons, the model is expected to have better phenomenological results, as well as providing a conceptually more unified picture of mesons and baryons. 29 references.

Caldi, D.G.

1984-01-01

369

Time-dependent spherically symmetric covariant Galileons  

NASA Astrophysics Data System (ADS)

We study spherically symmetric solutions of the cubic covariant Galileon model in curved spacetime in the presence of a matter source, in the test scalar field approximation. We show that a cosmological time evolution of the Galileon field gives rise to an induced matter-scalar coupling, due to the Galileon-graviton kinetic braiding, therefore the solution for the Galileon field is nontrivial even if the bare matter-scalar coupling constant is set to zero. The local solution crucially depends on the asymptotic boundary conditions, and in particular, Minkowski and de Sitter asymptotics correspond to different branches of the solution. We study the stability of these solutions, namely, the well posedness of the Cauchy problem and the positivity of energy for scalar and tensor perturbations, by diagonalizing the kinetic terms of the spin-2 and spin-0 degrees of freedom. In addition, we find that in the presence of a cosmological time evolution of the Galileon field, its kinetic mixing with the graviton leads to a friction force resulting in efficient damping of scalar perturbations within matter.

Babichev, Eugeny; Esposito-Farèse, Gilles

2013-02-01

370

Quantum Mechanics in Terms of Symmetric Measurements  

NASA Astrophysics Data System (ADS)

In the neo-Bayesian view of quantum mechanics that Appleby, Caves, Pitowsky, Schack, the author, and others are developing, quantum states are taken to be compendia of partial beliefs about potential measurement outcomes, rather than objective properties of quantum systems. Different observers may validly have different quantum states for a single system, and the ultimate origin of each individual state assignment is taken to be unanalyzable within physical theory---its origin, instead, comes from prior probability assignments at stages of physical investigation or laboratory practice previous to quantum theory. The objective content of quantum mechanics thus resides somewhere else than in the quantum state, and various ideas for where that ``somewhere else'' is are presently under debate. What is overwhelmingly agreed upon in this effort is only the opening statement. Still, quantum states are not Bayesian probability assignments themselves, and different representations of the theory (in terms of state vectors or Wigner functions or C*-algebras, etc.) can take one further from or closer to a Bayesian point of view. It is thus worthwhile thinking about which representation might be the most propitious for the point of view and might quell some of the remaining debate. In this talk, I will present several results regarding a representation of quantum mechanics in terms of symmetric bases of positive-semidefinite operators. I also argue why this is probably the most natural representation for a Bayesian-style quantum mechanics.

Fuchs, Christopher

2006-03-01

371

On symplectic and symmetric ARKN methods  

NASA Astrophysics Data System (ADS)

Symplecticness and symmetry are favorable properties for solving Hamiltonian systems. For the oscillatory second-order initial value problems of the form q+?q=f(q,q), adapted Runge-Kutta-Nyström methods (ARKN methods, in short notation) were investigated by several authors. In a wide range of physical applications from molecular dynamics to nonlinear wave propagation, an important class of the problems is Hamiltonian systems for which symplectic methods should be preferred. Hence it is quite natural to raise a question of the symplecticness for ARKN methods. In this paper we investigate the symplecticness conditions of ARKN methods for separable Hamiltonian systems. We conclude that there exist only one-stage explicit symplectic ARKN (SARKN, in short notation) methods under the symplecticness conditions of ARKN methods. The SARKN methods have a special form and the algebraic order cannot exceed 2. We also point out that no ARKN method can be symmetric. An explicit SARKN method of order two is proposed with the analysis of phase and stability properties. The numerical results accompanied show good performance for the new explicit symplectic algorithm in comparison with the popular symplectic methods in the scientific literature.

Shi, Wei; Wu, Xinyuan

2012-06-01

372

Measuring top-quark polarization in top-pair + missing-energy events.  

PubMed

The polarization of a top quark can be sensitive to new physics beyond the standard model. Since the charged lepton from top-quark decay is maximally correlated with the top-quark spin, it is common to measure the polarization from the distribution in the angle between the charged lepton and the top-quark directions. We propose a novel method based on the charged lepton energy fraction and illustrate the method with a detailed simulation of top-quark pairs produced in supersymmetric top squark pair production. We show that the lepton energy ratio distribution that we define is very sensitive to the top-quark polarization but insensitive to the precise measurement of the top-quark energy. PMID:23102297

Berger, Edmond L; Cao, Qing-Hong; Yu, Jiang-Hao; Zhang, Hao

2012-10-09

373

7. DETAIL OF TOP CHORD/END POST CONNECTION. THE TOPS OF ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. DETAIL OF TOP CHORD/END POST CONNECTION. THE TOPS OF BOTH MEMBERS ARE COVERED WITH SOLID PLATES. - Montgomery County Bridge No. 221, Metz Road spanning Towamencin Creek, Skippack, Montgomery County, PA

374

The status of molecules  

SciTech Connect

This report summarizes the experimental and theoretical status of hadronic molecules, which are weakly-bound states of two or more hadrons. We begin with a brief history of the subject and discuss a few good candidates, and then abstract some signatures for molecules which may be of interest in the classification of possible molecule states. Next we argue that a more general understanding of 2 {yields} 2 hadron-hadron scattering amplitudes will be crucial for molecule searches, and discuss some of our recent work in this area. We conclude with a discussion of a few more recent molecule candidates (notably the f{sub o}(1710)) which are not well established as molecules but satisfy some of the expected signatures.

Barnes, T. [Oak Ridge National Lab., TN (United States)]:[Tennessee Univ., Knoxville, TN (United States). Dept. of Physics and Astronomy

1994-10-01

375

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

PubMed

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

Mahapatro, Ajit K; Janes, David B

2007-06-01

376

World average top-quark mass  

SciTech Connect

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.

Glenzinski, D.; /Fermilab

2008-01-01

377

MAP\\/TOP in CIM distributed computing  

Microsoft Academic Search

The distributed computing communication needs of computer-integrated manufacturing (CIM) are discussed. The capabilities of MAP\\/TOP (manufacturing automation protocol\\/technical and office protocol) as a communications architecture are examined. An example of how MAP\\/TOP operates in a hypothetical CIM enterprise is presented

L. J. McGuffin; L. O. Reid; S. R. Sparks

1988-01-01

378

Top production cross section from CDF  

SciTech Connect

Recent top physics results from the CDF at a center-of-mass energy of 1.96 TeV are presented. Measurements of the t{bar t} production cross section in all three decay channels, using a set of complementary experimental methods, are presented as well as results of a search for single top production.

Taffard, Anyes; /Illinois U., Urbana

2004-12-01

379

49 CFR 236.779 - Plate, top.  

Code of Federal Regulations, 2010 CFR

...Transportation 4 2009-10-01 2009-10-01 false Plate, top. 236.779 Section 236.779 Transportation...DEVICES, AND APPLIANCES Definitions § 236.779 Plate, top. A metal plate secured to a locking bracket to prevent the cross...

2009-10-01

380

49 CFR 236.779 - Plate, top.  

Code of Federal Regulations, 2011 CFR

...Transportation 4 2011-10-01 2011-10-01 false Plate, top. 236.779 Section 236.779 Transportation...DEVICES, AND APPLIANCES Definitions § 236.779 Plate, top. A metal plate secured to a locking bracket to prevent the cross...

2011-10-01

381

49 CFR 236.779 - Plate, top.  

Code of Federal Regulations, 2012 CFR

...Transportation 4 2012-10-01 2012-10-01 false Plate, top. 236.779 Section 236.779 Transportation...DEVICES, AND APPLIANCES Definitions § 236.779 Plate, top. A metal plate secured to a locking bracket to prevent the cross...

2012-10-01

382

49 CFR 236.779 - Plate, top.  

Code of Federal Regulations, 2010 CFR

...Transportation 4 2010-10-01 2010-10-01 false Plate, top. 236.779 Section 236.779 Transportation...DEVICES, AND APPLIANCES Definitions § 236.779 Plate, top. A metal plate secured to a locking bracket to prevent the cross...

2010-10-01

383

Textured soy protein (TSP) as pizza topping  

Microsoft Academic Search

Purpose – The purpose of this paper is to investigate the stability of chicken flavored textured soy protein (TSP) substitution for chicken meat in pizza toppings. Design\\/methodology\\/approach – TSP obtained from defatted soy flour was used to replace chicken at 25, 50 and 100 percent level in the pizza toppings. Patent grade wheat flour, TSP, boiled chicken, cheese, pizza shell

Ghazala Qammar; Ghulam Mohy-ud-Din; Nuzhat Huma; Ayesha Sameen; Muhammad Issa Khan

2010-01-01

384

Race to Top Draws out New Suitors  

ERIC Educational Resources Information Center

|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…

McNeil, Michele

2012-01-01

385

Pinch Experiments in a Table Top Generator  

SciTech Connect

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.

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

386

Review of Top Quark Physics Results  

SciTech Connect

As the heaviest known fundamental particle, the top quark has taken a central role in the study of fundamental interactions. Production of top quarks in pairs provides an important probe of strong interactions. The top quark mass is a key fundamental parameter which places a valuable constraint on the Higgs boson mass and electroweak symmetry breaking. Observations of the relative rates and kinematics of top quark final states constrain potential new physics. In many cases, the tests available with study of the top quark are both critical and unique. Large increases in data samples from the Fermilab Tevatron have been coupled with major improvements in experimental techniques to produce many new precision measurements of the top quark. The first direct evidence for electroweak production of top quarks has been obtained, with a resulting direct determination of V{sub tb}. Several of the properties of the top quark have been measured. Progress has also been made in obtaining improved limits on potential anomalous production and decay mechanisms. This review presents an overview of recent theoretical and experimental developments in this field. We also provide a brief discussion of the implications for further efforts.

Kehoe, R.; Narain, M.; Kumar, A.

2007-12-01

387

Top-Ten IT Issues, 2008  

ERIC Educational Resources Information Center

|EDUCAUSE presents the top-ten IT-related issues in terms of strategic importance to the higher education institution, as revealed by the ninth annual EDUCAUSE Current Issues Survey. This year, "Security" moves back to the top of the list. (Contains 20 notes.)|

Allison, Debra H.; DeBlois, Peter B.

2008-01-01

388

Top Ten Homework Tips (For Parents)  

MedlinePLUS

... Staying Fit Flu Vaccine: How Many Doses? Connect With Us: Social Media Pregnant? Your Baby's Growth Top 10 Homework Tips KidsHealth > Parents > School & Family Life > Learning & Education > Top 10 Homework ... it shows kids that what they do is important. Of course, helping with homework shouldn't mean spending hours hunched over ...

389

Top 12 Web Resources for 2012  

ERIC Educational Resources Information Center

|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…

Gonzales, Lisa; Vodicka, Devin

2012-01-01

390

Measurement of the Top Quark Mass  

Microsoft Academic Search

We present a measurement of the top quark mass using a sample of tt¯ decays into an electron or a muon, a neutrino, and four jets. The data were collected in pp¯ collisions at s = 1.8 TeV with the Collider Detector at Fermilab and correspond to an integrated luminosity of 109 pb-1. We measure the top quark mass to

Steven R. Blusk; for the CDF; M. G. Albrow; A. Amadon; S. R. Amendolia; D. Amidei; J. Antos; S. Aota; G. Apollinari; T. Arisawa; T. Asakawa; W. Ashmanskas; M. Atac; P. Azzi-Bacchetta; N. Bacchetta; S. Bagdasarov; M. W. Bailey; P. de Barbaro; A. Barbaro-Galtieri; V. E. Barnes; B. A. Barnett; M. Barone; G. Bauer; T. Baumann; F. Bedeschi; S. Behrends; S. Belforte; G. Bellettini; J. Bellinger; D. Benjamin; J. Bensinger; A. Beretvas; J. P. Berge; J. Berryhill; S. Bertolucci; S. Bettelli; B. Bevensee; A. Bhatti; K. Biery; C. Bigongiari; M. Binkley; D. Bisello; R. E. Blair; C. Blocker; A. Bodek; W. Bokhari; G. Bolla; Y. Bonushkin; D. Bortoletto; J. Boudreau; L. Breccia; C. Bromberg; N. Bruner; R. Brunetti; E. Buckley-Geer; H. S. Budd; K. Burkett; G. Busetto; A. Byon-Wagner; K. L. Byrum; M. Campbell; A. Caner; W. Carithers; D. Carlsmith; J. Cassada; A. Castro; D. Cauz; A. Cerri; P. S. Chang; H. Y. Chao; J. Chapman; M.-T. Cheng; M. Chertok; G. Chiarelli; C. N. Chiou; F. Chlebana; L. Christofek; M. L. Chu; S. Cihangir; A. G. Clark; M. Cobal; E. Cocca; M. Contreras; J. Conway; J. Cooper; M. Cordelli; D. Costanzo; C. Couyoumtzelis; D. Cronin-Hennessy; R. Culbertson; D. Dagenhart; T. Daniels; F. Dejongh; S. dell'Agnello; M. dell'Orso; R. Demina; L. Demortier; M. Deninno; P. F. Derwent; T. Devlin; J. R. Dittmann; S. Donati; J. Done; T. Dorigo; N. Eddy; K. Einsweiler; J. E. Elias; R. Ely; E. Engels; W. Erdmann; D. Errede; S. Errede; Q. Fan; R. G. Feild; Z. Feng; C. Ferretti; I. Fiori; B. Flaugher; G. W. Foster; M. Franklin; J. Freeman; J. Friedman; H. Frisch; Y. Fukui; S. Gadomski; S. Galeotti; M. Gallinaro; O. Ganel; M. Garcia-Sciveres; A. F. Garfinkel; C. Gay; S. Geer; D. W. Gerdes; P. Giannetti; N. Giokaris; P. Giromini; G. Giusti; M. Gold; A. Gordon; A. T. Goshaw; Y. Gotra; K. Goulianos; H. Grassmann; L. Groer; C. Grosso-Pilcher; G. Guillian; J. Guimaraes da Costa; R. S. Guo; C. Haber; E. Hafen; S. R. Hahn; T. Handa; R. Handler; F. Happacher; K. Hara; A. D. Hardman; R. M. Harris; F. Hartmann; J. Hauser; E. Hayashi; J. Heinrich; W. Hao; B. Hinrichsen; K. D. Hoffman; M. Hohlmann; C. Holck; R. Hollebeek; L. Holloway; Z. Huang; B. T. Huffman; R. Hughes; J. Huston; J. Huth; H. Ikeda; M. Incagli; J. Incandela; G. Introzzi; J. Iwai; Y. Iwata; E. James; H. Jensen; U. Joshi; E. Kajfasz; H. Kambara; T. Kamon; T. Kaneko; K. Karr; H. Kasha; Y. Kato; T. A. Keaffaber; K. Kelley; R. D. Kennedy; R. Kephart; D. Kestenbaum; D. Khazins; T. Kikuchi; B. J. Kim; H. S. Kim; S. H. Kim; Y. K. Kim; L. Kirsch; S. Klimenko; D. Knoblauch; P. Koehn; A. Köngeter; K. Kondo; J. Konigsberg; K. Kordas; A. Korytov; E. Kovacs; W. Kowald; J. Kroll; M. Kruse; S. E. Kuhlmann; E. Kuns; K. Kurino; T. Kuwabara; A. T. Laasanen; S. Lami; S. Lammel; J. I. Lamoureux; M. Lancaster; M. Lanzoni; G. Latino; T. Lecompte; S. Leone; J. D. Lewis; P. Limon; M. Lindgren; T. M. Liss; J. B. Liu; Y. C. Liu; N. Lockyer; O. Long; C. Loomis; M. Loreti; D. Lucchesi; P. Lukens; S. Lusin; J. Lys; K. Maeshima; P. Maksimovic; M. Mangano; M. Mariotti; J. P. Marriner; A. Martin; J. A. Matthews; P. Mazzanti; P. McIntyre; P. Melese; M. Menguzzato; A. Menzione; E. Meschi; S. Metzler; C. Miao; T. Miao; G. Michail; R. Miller; H. Minato; S. Miscetti; M. Mishina; S. Miyashita; N. Moggi; E. Moore; Y. Morita; A. Mukherjee; T. Muller; P. Murat; S. Murgia; H. Nakada; I. Nakano; C. Nelson; D. Neuberger; C. Newman-Holmes; C.-Y. P. Ngan; L. Nodulman; A. Nomerotski; S. H. Oh; T. Ohmoto; T. Ohsugi; R. Oishi; M. Okabe; T. Okusawa; J. Olsen; C. Pagliarone; R. Paoletti; V. Papadimitriou; S. P. Pappas; N. Parashar; A. Parri; J. Patrick; G. Pauletta; M. Paulini; A. Perazzo; L. Pescara; M. D. Peters; T. J. Phillips; G. Piacentino; M. Pillai; K. T. Pitts; R. Plunkett; L. Pondrom; J. Proudfoot; F. Ptohos; G. Punzi; K. Ragan; D. Reher; M. Reischl; A. Ribon; F. Rimondi; L. Ristori; W. J. Robertson; T. Rodrigo; S. Rolli; L. Rosenson; R. Roser; T. Saab; W. K. Sakumoto; D. Saltzberg; A. Sansoni; L. Santi; H. Sato; P. Schlabach; E. E. Schmidt; M. P. Schmidt; A. Scott; A. Scribano; S. Segler; S. Seidel; Y. Seiya; F. Semeria; T. Shah; M. D. Shapiro; N. M. Shaw; P. F. Shepard; T. Shibayama; M. Shimojima; M. Shochet; J. Siegrist; A. Sill; P. Sinervo; P. Singh; K. Sliwa; C. Smith; F. D. Snider; J. Spalding; T. Speer; P. Sphicas; F. Spinella; M. Spiropulu; L. Spiegel; L. Stanco; J. Steele; A. Stefanini; R. Ströhmer; J. Strologas; F. Strumia; D. Stuart; K. Sumorok; J. Suzuki; T. Suzuki; T. Takahashi; T. Takano; R. Takashima; K. Takikawa; M. Tanaka; B. Tannenbaum; F. Tartarelli; W. Taylor; M. Tecchio; P. K. Teng; Y. Teramoto; K. Terashi; S. Tether; D. Theriot; T. L. Thomas; R. Thurman-Keup; M. Timko; P. Tipton; A. Titov; S. Tkaczyk; D. Toback; K. Tollefson; A. Tollestrup; H. Toyoda; W. Trischuk; J. F. de Troconiz; S. Truitt; J. Tseng; N. Turini; T. Uchida; F. Ukegawa; J. Valls; S. C. van den Brink; S. Vejcik

1998-01-01

391

Earth Observatory: The Top of the Atmosphere  

NSDL National Science Digital Library

This webpage from NASA provides an astronautâs photograph of the moon viewed from the top of the atmosphere. The appearance of the nearly translucent moon is described in regards to optics, and an introduction to NASAâs observations of the top of the atmosphere is provided. The site also contains links to numerous new images from the Earth Observatory.

2007-03-26

392

Top Quark Pair Production at the Tevatron  

SciTech Connect

The measurement of the top quark pair production crosssection inproton-antiproton collisions at 1.96 TeV is a test ofquantumchromodynamics and could potentially be sensitive to newphysics beyondthe standard model. I report on the latest t-tbarcross section resultsfrom the CDF and DZero experiments in various finalstate topologies whicharise from decays of top quark pairs.

Nielsen, Jason

2005-05-17

393

Theoretical modelling of non-symmetric circular piezoelectric bimorphs  

NASA Astrophysics Data System (ADS)

This paper deals with the theoretical modelling of non-symmetric and symmetric circular bimorphs. The model is restricted to the study of flexural vibration modes having radial symmetry (axisymmetry), as is often the case for piezoelectric devices such as MEMs. The calculation of the resonance frequencies and the displacement of the non-symmetric circular bimorph has been carried out and the influence of the elastic and geometric parameters of the cement layer has been introduced into the model. As is shown, the modelling of non-symmetric and symmetric circular bimorphs reduces to the determination of two global quantities: the global rigidity DG and the global Poisson ratio ?G of the bimorph which is then equivalent to a homogenous element. Consequently, the results obtained with elastic and homogeneous circular plates can be applied to non-symmetric and symmetric bimorphs with the only condition of using the global DG and ?G. The new modelling was applied to bimorph functioning either as an actuator or as a sensor and having a simply supported or clamped edge. The electromechanical coupling factor of flexure modes has been calculated and compared to the radial mode. Comparison between analytical models and simulations using the finite-element method is given and discussed.

Brissaud, Michel

2006-05-01

394

Synchrotron Storage Ring for Neutral Polar Molecules  

NASA Astrophysics Data System (ADS)

We have modeled the performance of a molecular synchrotron storage ring. Using 90 m/s deuterated ammonia (ND_3) as an example [1], we specify the shape, size, field, and placement of all of the electrostatic bending, focusing [2], bunching, and injection elements needed for a desk-top sized ring. With a newly developed code, we designed a race track lattice and tracked molecules for 400 turns to determine the dynamic aperture and momentum acceptance of the synchrotron storage ring. Results will be presented. [1] F. Crompvoets et al, Nature 411, 174 (2001) [2] J. Kalnins et. al., http://arXiv.org/abs/physics/0112073

Gould, Harvey

2002-05-01

395

TOP500 Supercomputers for June 2002  

SciTech Connect

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.

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

2002-06-20

396

Protein Identification Using Top-Down  

SciTech Connect

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.

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

397

Top Mass Measurements at the Tevatron  

SciTech Connect

First observed in 1995, the top quark is the third-generation up-type quark of the standard model of particle physics (SM). The CDF and D0 collaborations have analyzed many t{bar t} events produced by the Tevatron collider, studying many properties of the top quark. Among these, the mass of the top quark is a fundamental parameter of the SM, since its value constrains the mass of the yet to be observed Higgs boson. The analyzed events were used to measure the mass of the top quark m{sub t} {approx_equal} 173.2 GeV/c{sup 2} with an uncertainty of less than 1 GeV/c{sup 2}. We report on the latest top mass measurements at the Tevatron, using up to 6 fb{sup -1} of data for each experiment.

Potamianos, Karolos; /Purdue U.

2012-01-01

398

Experimental scheme for unambiguous discrimination of linearly independent symmetric states  

SciTech Connect

We propose an experimental setup for discriminating four linearly independent nonorthogonal symmetric quantum states. The setup is based on linear optics only and can be configured to implement both optimal unambiguous state discrimination [Chefles and Barnett, Phys. Lett. A 250, 223 (1998)] and minimum error discrimination. In both cases, the setup is characterized by an optimal success probability. The experimental setup can be generalized to the case of discrimination among N linearly nonorthogonal symmetric quantum states. We also study the discrimination between two incoherent superpositions of symmetric states. In this case, the setup also achieves an optimal success probability in the case of unambiguous discrimination as well as minimum error discrimination.

Jimenez, O.; Burgos-Inostroza, E.; Delgado, A.; Saavedra, C. [Center for Quantum Optics and Quantum Information, Departamento de Fisica, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Sanchez-Lozano, X. [Center for Quantum Optics and Quantum Information, Departamento de Fisica, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Instituto de Fisica, Universidad de Guanajuato, P. O. Box E-143, 37150, Leon Guanajuato (Mexico)

2007-12-15

399

Study on the symmetric line-laser rut measurement  

NASA Astrophysics Data System (ADS)

The rut results based on the line-laser rut measurement are often subjected to the vehicle bumps, vehicle pitch changes in practical applications. The principle of line-laser rut measurement is described and the factors are analyzed from the perspective of optical imaging. A new method of symmetrical line-laser rut measurement is proposed. This method uses symmetric line-laser imaging system and can effectively reduce the rut test errors caused by the vehicle bumps, vehicle pitch changes. Experimental results show that the symmetric line-laser rut measurement can be used to detect road surface rut.

Song, Hongxun; Fang, Cui

2010-11-01

400

Geometric characteristics of aberrations of plane-symmetric optical systems  

SciTech Connect

The geometric characteristics of aberrations of plane-symmetric optical systems are studied in detail with a wave-aberration theory. It is dealt with as an extension of the Seidel aberrations to realize a consistent aberration theory from axially symmetric to plane-symmetric systems. The aberration distribution is analyzed with the spot diagram of a ray and an aberration curve. Moreover, the root-mean-square value and the centroid of aberration distribution are discussed. The numerical results are obtained with the focusing optics of a toroidal mirror at grazing incidence.

Lu Lijun; Deng Zhiyong

2009-12-20

401

A Windows based graphical package for symmetrical components analysis  

SciTech Connect

A Microsoft{reg_sign} Windows{trademark} graphical package to facilitate the teaching and learning of symmetrical component is described in this paper. This package is written in Microsoft Visual Basic 3.0. This software calculates and displays graphically, the ABC sequence and the corresponding symmetrical component phasors. Students can manipulate the graphical displays by keyboard input or by mouse operation. The objective of this package is to help the students to better understand the various aspects of symmetrical components` analysis through a user-friendly Graphical User Interface (GUI).

Yu, D.C.; Chen, D.; Ramasamy, S. [Univ. of Wisconsin, Milwaukee, WI (United States); Flinn, D.G. [Cooper Power System, Franksville, WI (United States)

1995-11-01

402

Symmetric diffeomorphic registration of fibre orientation distributions.  

PubMed

Registration of diffusion-weighted images is an important step in comparing white matter fibre bundles across subjects, or in the same subject at different time points. Using diffusion-weighted imaging, Spherical Deconvolution enables multiple fibre populations within a voxel to be resolved by computing the fibre orientation distribution (FOD). In this paper, we present a novel method that employs FODs for the registration of diffusion-weighted images. Registration was performed by optimising a symmetric diffeomorphic non-linear transformation model, using image metrics based on the mean squared difference, and cross-correlation of the FOD spherical harmonic coefficients. The proposed method was validated by recovering known displacement fields using FODs represented with maximum harmonic degrees (l(max)) of 2, 4 and 6. Results demonstrate a benefit in using FODs at l(max)=4 compared to l(max)=2. However, a decrease in registration accuracy was observed when l(max)=6 was used; this was likely caused by noise in higher harmonic degrees. We compared our proposed method to fractional anisotropy driven registration using an identical code base and parameters. FOD registration was observed to perform significantly better than FA in all experiments. The cross-correlation metric performed significantly better than the mean squared difference. Finally, we demonstrated the utility of this method by computing an unbiased group average FOD template that was used for probabilistic fibre tractography. This work suggests that using crossing fibre information aids in the alignment of white matter and could therefore benefit several methods for investigating population differences in white matter, including voxel based analysis, tensor based morphometry, atlas based segmentation and labelling, and group average fibre tractography. PMID:21316463

Raffelt, David; Tournier, J-Donald; Fripp, Jurgen; Crozier, Stuart; Connelly, Alan; Salvado, Olivier

2011-02-18

403

Malachite Green Mediates Homodimerization of Antibody VL Domains to Form a Fluorescent Ternary Complex with Singular Symmetric Interfaces.  

PubMed

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

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

2013-08-23

404

Discovery of single top quark production  

SciTech Connect

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.

Gillberg, Dag; /Simon Fraser U.

2009-05-01

405

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...

406

Single Molecule Spectroscopy  

Microsoft Academic Search

We report unambiguous optical detection of single molecules of pentacene in p-terphenyl crystal. The relative shift of the molecular resonance frequencies with temperature changes demonstrates the phenomenon of activated spectral diffusion. These results show the feasibility of the optical study of a single molecule and its local environment.

M. Orrit; J. Bernard

1991-01-01

407

Single Molecule Spectroscopy  

NASA Astrophysics Data System (ADS)

We report unambiguous optical detection of single molecules of pentacene in p-terphenyl crystal. The relative shift of the molecular resonance frequencies with temperature changes demonstrates the phenomenon of activated spectral diffusion. These results show the feasibility of the optical study of a single molecule and its local environment.

Orrit, M.; Bernard, J.

408

What is a Molecule?  

NSDL National Science Digital Library

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

Wpsu

2007-04-09

409

Computing with Molecules  

NSDL National Science Digital Library

This site covers the interesting new frontier of molecular computing, which links molecular biology with computer science. The article "Computing with Molecules" from Scientific American's June issue (available for free online) describes how researchers are using organic molecules to perform simple logic operations. This technology is important because it could be used to make extremely tiny computers.

Reed, Mark A.; Tour, James M.

2000-01-01

410

Positron-Molecule Interactions.  

National Technical Information Service (NTIS)

The objective of this research was to study the interaction of positrons with molecules at energies below the threshold for positronium atom formation. While there is evidence that positrons bind, or form long-lived resonances with large atoms and molecul...

C. M. Surko

1994-01-01

411

Single-Molecule Cellular Biophysics  

NASA Astrophysics Data System (ADS)

1. Once upon a (length and) time (scale) -; 2. The molecules of life; 3. Making the invisible visible: part 1; 4. Making the invisible visible: part 2; 5. Measuring forces and manipulating single molecules; 6. Single molecule biophysics; 7. Molecules from beyond; 8. Into the membrane; 9. Inside cells; 10. Single molecule biophysics beyond the single cell and beyond the single molecule; Index.

Leake, Mark C.

2013-01-01

412

Molecular docking guided structure based design of symmetrical N,N'-disubstituted urea/thiourea as HIV-1 gp120-CD4 binding inhibitors.  

PubMed

Induced fit molecular docking studies were performed on BMS-806 derivatives reported as small molecule inhibitors of HIV-1 gp120-CD4 binding. Comprehensive study of protein-ligand interactions guided in identification and design of novel symmetrical N,N'-disubstituted urea and thiourea as HIV-1 gp120-CD4 binding inhibitors. These molecules were synthesized in aqueous medium using microwave irradiation. Synthesized molecules were screened for their inhibitory ability by HIV-1 gp120-CD4 capture enzyme-linked immunosorbent assay (ELISA). Designed compounds were found to inhibit HIV-1 gp120-CD4 binding in micromolar (0.013-0.247 ?M) concentrations. PMID:23777826

Sivan, Sree Kanth; Vangala, Radhika; Manga, Vijjulatha

2013-06-01

413

Synthesis of a new class of carborane-containing star-shaped molecules via silicon tetrachloride promoted cyclotrimerization reactions.  

PubMed

Symmetrical star-shaped molecules with carborane clusters on the periphery have been synthesized in good yields via silicon tetrachloride mediated cyclotrimerization reactions of 9-benzyl derivatives of carboranes with acetyl group substitution on the benzene ring. Facile functionalization of these symmetrical core structures with 1-iodoheptane and trivinylchlorosilane produce compounds which could be used as liquid crystalline substances and precursors for synthesis of higher order carbosilane dendrons. PMID:18465864

Dash, Barada Prasanna; Satapathy, Rashmirekha; Maguire, John A; Hosmane, Narayan S

2008-05-09

414

Single-molecule optoelectronics.  

PubMed

With discrete states, several-atom Ag(n) nanoclusters exhibit molecule-like behavior with strong visible fluorescence and robust optical properties. This new class of single-molecule fluorophores has been created and electrically contacted in thin films to produce the first electroluminescent single molecules. A direct reporter of nanoscale charge injection and transport through discrete energy levels, bright Ag(n) electroluminescence has been harnessed to create single-molecule light-emitting diodes (LEDs) and optoelectronic logic gates and even to demonstrate full addition operations. These experiments utilizing the small size and quantum behavior of individual Ag nanoclusters usher in the new field of single-molecule optoelectronics. PMID:16028887

Lee, Tae-Hee; Gonzalez, Jose I; Zheng, Jie; Dickson, Robert M

2005-07-01

415

THE TOP QUARK, QCD, AND NEW PHYSICS.  

SciTech Connect

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.

DAWSON,S.

2002-06-01

416

Deuterium in North Atlantic storm tops  

SciTech Connect

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. 28 refs.

Smith, R.B. (Yale Univ., New Haven, CT (United States))

1992-11-01

417

Measurement of the top quark mass  

SciTech Connect

The first evidence and subsequent discovery of the top quark was reported nearly 4 years ago. Since then, CDF and D0 have analyzed their full Run 1 data samples, and analysis techniques have been refined to make optimal use of the information. In this paper, we report on the most recent measurements of the top quark mass, performed by the CDF and D0 collaborations at the Fermilab Tevatron. The CDF collaboration has performed measurements of the top quark mass in three decay channels from which the top quark mass is measured to be 175.5 {+-} 6.9 GeV=c{sup 2}. The D0 collaboration combines measurements from two decay channels to obtain a top quark mass of 172.1 {+-} 7.1 GeV/c{sup 2}. Combining the measurements from the two experiments, assuming a 2 GeV GeV/c{sup 2} correlated systematic uncertainty, the measurement of the top quark mass at the Tevatron is 173.9 {+-} 5.2 GeV/c{sup 2}. This report presents the measurements of the top quark mass from each of the decay channels which contribute to this measurement.

Blusk, Steven R.

1998-05-01

418

Top-quark charge asymmetry with a jet handle  

NASA Astrophysics Data System (ADS)

Pairs of top and antitop quarks are produced at the LHC to a large extent in association with a hard jet. We investigate the charge asymmetry in tt¯+j production in quantum chromodynamics (QCD) and with additional massive color-octet vector bosons. The total charge asymmetry at the LHC is suppressed by the large charge-symmetric background from gluon-gluon fusion. We show to what extent the asymmetry can be enhanced by suitable phase space cuts and, in particular, elaborate on the kinematics of the hard jet in the tt¯+j final state. We demonstrate that in QCD, the asymmetry amounts to 1.5% for central jets without an excessive reduction of the cross section. By applying additional kinematical cuts, the asymmetry can be enhanced to 4%, but at the cost of a strong reduction of the cross section. Massive color-octet states can generate sizeable effects in tt¯+j production, both on the charge asymmetry and on the cross section. The charge asymmetry probes both vector and axial-vector couplings to quarks. We show that massive color octets can generate asymmetries up to ±10% for moderate and up to ±30% for strong kinematical cuts to be used in experimental analyses at the LHC. Jet kinematics can be used to obtain further information about the nature of the couplings and thereby to discriminate between different models.

Berge, Stefan; Westhoff, Susanne

2012-11-01

419

Thermal Buckling and Postbuckling of Symmetrically Laminated Composite Plates.  

National Technical Information Service (NTIS)

The paper discusses an investigation into thermal buckling and postbuckling of symmetrically laminated composite plates. In the study thermal buckling is investigated for laminates under two different simple support conditions, fixed and sliding. These la...

C. A. Meyers M. W. Hyer M. J. Shuart

1991-01-01

420

mathcal{PT}-Symmetric Quantum Electrodynamics—mathcal{PT}QED  

NASA Astrophysics Data System (ADS)

The construction of mathcal{PT}-symmetric quantum electrodynamics is reviewed. In particular, the massless version of the theory in 1+1 dimensions (the Schwinger model) is solved. Difficulties with unitarity of the S-matrix are discussed.

Milton, Kimball A.; Cavero-Peláez, Inés; Parashar, Prachi; Shajesh, K. V.; Wagner, J.

2011-04-01

421

Equatorial Superrotation in a Thermally Driven Zonally Symmetric Circulation.  

National Technical Information Service (NTIS)

Near the equator where the Coriolis force vanishes, the momentum balance for the axially symmetric circulation is established between horizontal and vertical diffusion, which, a priori, does not impose constraints on the direction or magnitude of the zona...

H. G. Mayr I. Harris

1981-01-01

422

47 CFR 51.711 - Symmetrical reciprocal compensation.  

Code of Federal Regulations, 2012 CFR

...of Telecommunications Traffic § 51.711 Symmetrical reciprocal compensation...incumbent LEC serves a geographic area comparable to the area served by the incumbent LEC's... (b) Except as provided in § 51.705, a state commission...

2012-10-01

423

Dirac operators with a spherically symmetric delta-shell interaction.  

National Technical Information Service (NTIS)

We study Dirac operators with a contact interaction supported by a sphere restricting our attention to the operators which are rotationally and space-reflection symmetric. The partial-wave operators are constructed using the self-adjoint extension theory,...

J. Dittrich P. Exner P. Seba

1989-01-01

424

New multichannel electron energy analyzer with cylindrically symmetrical electrostatic field  

SciTech Connect

This article discusses an electron energy analyzer with a cylindrically symmetrical electrostatic field, designed for rapid Auger analysis. The device was designed and built. The best parameters of the analyzer were estimated and then experimentally verified.

Cizmar, P.; Muellerova, I.; Jacka, M.; Pratt, A. [Institute of Scientific Instruments, ASCR, Kralovopolska 147, Brno CZ-61264 (Czech Republic)

2007-05-15

425

New multichannel electron energy analyzer with cylindrically symmetrical electrostatic field  

Microsoft Academic Search

This article discusses an electron energy analyzer with a cylindrically symmetrical electrostatic field, designed for rapid Auger analysis. The device was designed and built. The best parameters of the analyzer were estimated and then experimentally verified.

P. Cizmar; I. Muellerova; M. Jacka; A. Pratt

2007-01-01

426

The Isotopic Anatomies of Molecules and Minerals  

NASA Astrophysics Data System (ADS)

Most natural compounds are composed of diverse isotopologues that differ in the number and/or symmetrically unique atomic locations of isotopic substitutions. Little of this isotopic diversity is observed by conventional methods of stable isotope geochemistry, which generally measure concentrations of rare isotopes without constraining differences in isotopic composition between different atomic sites or nonrandom probabilities of multiple isotopic substitutions in the same molecule. Recent advances in analytical instrumentation and methodology have created a set of geochemical tools—geothermometers, biosynthetic signatures, forensic fingerprints—based on these position-specific isotope effects and multiply substituted isotopologues. This progress suggests we are entering a period in which many new geochemical tools of this type will be created. This review describes the principles, background, analytical methods, existing applied tools, and likely future progress of this emerging field.

Eiler, John M.

2013-05-01

427

Low-Lying Excited States of the Hydrogen Molecule in Cylindrical Harmonic Confinement  

NASA Astrophysics Data System (ADS)

The low-lying excited states of the hydrogen molecule confined in the harmonic potential were studied using the configuration interaction method and large basis sets. Axially symmetric harmonic oscillator potentials were used. The effect of the confinement on the geometry and spectroscopic constants was analyzed. Detailed analysis of the effect of confinement on the composition of the wavefunction was performed.

Lo, John M. H.; Klobukowski, Mariusz; Diercksen, Geerd H. F.

428

Single top quark production at D0  

SciTech Connect

We present first evidence for the production of single top quarks at the Fermilab Tevatron p{bar p} collider. Using a 0.9 fb{sup -1} dataset, we apply a multivariate analysis to separate signal from background and measure cross section for single top quark production. We use the cross section measurement to directly determine the CKM matrix element that describes the Wtb coupling. We also present results of W0 and charged Higgs searches with the same final states as standard model single top quark production.

Jabeen, S.; /Boston U.

2008-07-01

429

The search for top at CDF  

SciTech Connect

We present results on the search for the top quark in {bar p}p collisions at {radical}s = 1.8 TeV. The data sample collected during the 1988--89 run with the Collider Detector at Fermilab (CDF) includes more than 4 pb{sup {minus}1}. We report here on an extension of previously published searches for the top quark in electron + jets and the dilepton channel electron-muon. The 95% confidence level limit on the top mass is 89 GeV/c{sup 2}.

Liss, T.M. [Illinois Univ., Urbana, IL (United States). Loomis Lab. of Physics; CDF Collaboration

1991-08-01

430

Top quark physics at the Tevatron  

SciTech Connect

The Tevatron proton-antiproton collider at Fermilab with its centre of mass energy of 1.96 TeV is currently the only source for the production of top quarks. Its increased luminosity and centre of mass energy in Run II allow both collider detectors CDF and D0 to study top quarks with unprecedented scrutiny. Recent results on the top quark's pair production cross section and its properties such as mass, electric charge, helicity of the W boson in its decay and branching fraction B(t {yields} Wb) are presented and probe the validity of the Standard Model.

Pleier, M.A.; /Bonn U.

2007-09-01

431

Precision Determination of the Top Quark Mass  

SciTech Connect

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}.

Movilla Fernandez, Pedro A.; /LBL, Berkeley

2007-05-01

432

Single Top Production at the Tevatron  

SciTech Connect

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.

Wu, Zhenbin; /Baylor U.

2012-05-01

433

Top Quark Production at the Tevatron  

SciTech Connect

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.

Mietlicki, David J.

2011-12-01

434

Top quark properties from the Tevatron  

SciTech Connect

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.

Klute, Markus; /MIT, LNS

2006-05-01

435

Top quark mass measurement at the Tevatron  

SciTech Connect

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.

Guimaraes da Costa, Joao; /Harvard U.

2004-12-01

436

Various photonic crystal structures fabricated by using a top-cut hexagonal prism  

NASA Astrophysics Data System (ADS)

We demonstrate a holographic approach for the fabrication of large-area photonic crystal (PhC) microstructures by applying a single top-cut hexagonal prism (TCHP). The interference patterns of the beams from the TCHP are calculated. Various two-dimensional PhC structures are fabricated in photo-resist films. They include symmetrical hexagonal structures, the honey-comb structure and the hexagonal structure with skewed elliptical rods. The first structures come from six-beam and symmetrical three-beam interfering. The second structure appears when the beam is incident on the TCHP obliquely. The third structure is obtained when adjacent three beams or four beams are interfered. The period can be decreased to 285 nm. SPM observations of the PhCs provide the basis for measurement of their structural parameters. A good agreement is obtained for the measured structural parameters and calculated results for the PhCs. The photonic band gaps of the hexagonal symmetrical and honeycomb structures are derived by using the plane wave method. These results reveal that, by varying the number of split beams and the incident angle, using the single TCHP PhCs, different band gaps can be achieved.

Sun, X. H.; Tao, X. M.; Wang, Y. Y.

2010-02-01

437

The Use and Misuse of Conditional Symmetric Instability  

Microsoft Academic Search

ABSTRACT A commonly,employed,explanation for single- and multiple-banded clouds and precipitation in the extratropics is slantwise convection due to the release of moist symmetric instability (MSI), of which one type is conditional symmetric,instability (CSI). This article presents a review of CSI with the intent of synthesizing the results from previous observational, theoretical, and modeling studies. This review contends that CSI as

David M. Schultz; Philip N. Schumacher

1999-01-01

438

Symmetric monopoles and finite-gap Lamé potentials  

Microsoft Academic Search

For each positive integer g, we construct a one-parameter family of spectral curves for 0305-4470\\/29\\/16\\/035\\/img1 symmetric charge 2g+1 SU(2) BPS monopoles. Each spectral curve is reducible, and is the union of a line with g elliptic curves. We show that such a monopole is related to a g-gap Lamé potential. Other symmetric monopoles, related to elliptic curves, are also shown

Paul M. Sutcliffe

1996-01-01

439

Solitons in PT-symmetric potential with competing nonlinearity  

NASA Astrophysics Data System (ADS)

We investigate the effect of competing nonlinearities on beam dynamics in PT-symmetric potentials. In particular, we consider the stationary nonlinear Schrödinger equation (NLSE) in one dimension with competing cubic and generalized nonlinearity in the presence of a PT-symmetric potential. Closed form solutions for localized states are obtained. These solitons are shown to be stable over a wide range of potential parameters. The transverse power flow associated with these complex solitons is also examined.

Khare, Avinash; Al-Marzoug, S. M.; Bahlouli, Hocine

2012-10-01

440

Decentralized control of time-delayed uncertain symmetric composite systems  

Microsoft Academic Search

Reduced-order control design for a class of time–delayed uncertain nonlinear but nominally linear systems composed of identical nominal subsystems and symmetric interconnections is presented. Symmetric composite systems with time–delays and bounded parametric uncertainties both in subsystems and interconnections system matrices are considered for decentralized output control design using a controller–observer scheme. Luenberger–like delay–less observer is considered. First, an artificial reduced-order

L. Bakule

2003-01-01

441

PT-symmetric optical potentials in a coherent atomic medium  

NASA Astrophysics Data System (ADS)

We propose that a coherently prepared four-level atomic medium can provide a versatile platform for realizing parity-time (PT) symmetric optical potentials. Different types of PT-symmetric potentials are proposed by appropriately tuning the exciting optical fields and the pertinent atomic parameters. Such reconfigurable and controllable systems may open up new avenues in observing PT-related phenomena with appreciable gain-loss contrast in coherent atomic media.

Sheng, Jiteng; Miri, Mohammad-Ali; Christodoulides, Demetrios N.; Xiao, Min

2013-10-01

442

Dynamical Effect of Electromagnetic Wave in Spherical Symmetrical Finsler Spacetime  

NASA Astrophysics Data System (ADS)

In this paper, the dynamical effect of electromagnetic wave is researched in spherical symmetrical Finsler spacetime. The results show that the effect of tangent vector, which can be determined by the angular momentum and energy of observed particles, can't change the gravitational lens, but can influence the radar echo delay in spherical symmetrical Finsler spacetime. On the other hand, we also use the first order WKB method to study the electromagnetic perturbation with tangent vector effect of Finsler black hole.

Yang, Shuzheng; Lin, Kai

2013-09-01

443

Generalized symmetric extension for size-limited multirate filter banks  

Microsoft Academic Search

A multirate (MR) filter bank is called size-limited if the total number of output samples equals the number of input samples. A method called symmetric extension improved performance in subband image compression systems compared to the earlier method of circular convolution. However, the symmetric extension method was developed only for two-band uniform filter banks, and required even-length linear phase analysis

Roberto H. Bamberger; Steven L. Eddins; Veyis Nuri

1994-01-01

444

Classification of Nonexpansive Symmetric Extension Transforms for Multirate Filter Banks  

Microsoft Academic Search

This paper describes and classifies a family of invertible discrete-time signal transforms, referred to assymmetric extension transforms(SET's), for finite-length signals. SET's are algorithms for applying perfect reconstruction multirate filter banks to symmetric extensions of finite-length signals, thereby avoiding the boundary artifacts introduced by simple periodic extension. A key point is when such symmetric decompositions can be formed with no increase

Christopher M. Brislawn

1996-01-01

445

On the use of permanent symmetric scatterers for ship characterization  

Microsoft Academic Search

The symmetric scattering characterization method (SSCM) has been recently introduced for high-resolution characterization of certain targets under coherent conditions. SSCM is based on the Poincare´ sphere representation, which supports a high-resolution decomposition of symmetric target scattering, as well as assessment and validation of the backscatter coherence. In this paper, the SSCM is investigated for ship characterization using Convair-580 polarimetric synthetic

Ridha Touzi; R. Keith Raney; François Charbonneau

2004-01-01

446

The Lie algebraic significance of symmetric informationally complete measurements  

Microsoft Academic Search

Examples of symmetric informationally complete positive operator-valued measures (SIC-POVMs) have been constructed in every dimension ?67. However, it remains an open question whether they exist in all finite dimensions. A SIC-POVM is usually thought of as a highly symmetric structure in quantum state space. However, its elements can equally well be regarded as a basis for the Lie algebra gl(d,C).

D. M. Appleby; Steven T. Flammia; Christopher A. Fuchs

2011-01-01

447

Conservation Properties of Symmetric BVMs Applied to Linear Hamiltonian Problems  

Microsoft Academic Search

We consider the application of symmetric Boundary Value Methods to linear autonomous Hamiltonian systems. The numerical approximation\\u000a of the Hamiltonian function exhibits a superconvergence property, namely its order of convergence is p + 2 for a p order symmetric method. We exploit this result to define a natural projection procedure that slightly modifies the numerical\\u000a solution so that, without changing

Pierluigi Amodio; Felice Iavernaro; Donato Trigiante

2002-01-01

448

Bifurcations in a non-symmetric cubic potential.  

NASA Astrophysics Data System (ADS)

For a Hamiltonian corresponding to a perturbed couple of harmonic oscillators -but without symmetries- we obtain the evolution phase flow of the reduced Hamiltonian. The loss of symmetry produces a bifurcation that does not appear in the symmetric case, namely, one where a stable point crosses an unstable point yielding a cusp in the level curve. This result may be considered as a warning to some of the conclusions derived in galactic dynamics from too symmetric Hamiltonian.

Elipe, A.; Miller, B.; Vallejo, M.

1995-08-01

449

Products of correlated symmetric matrices and q Catalan numbers  

Microsoft Academic Search

.  ?The well known convergence of the spectrum of large random symmetric matrices, due to Wigner, holds for products of correlated\\u000a symmetric matrices with general entries. The limiting moments coincide with weighted enumeration of permutations, or of rooted\\u000a trees. When the correlations are Markovian, the limiting first moments are closely related to Carlitz-Riordan q-Catalan numbers. As a consequence, these moments asymptotically

Christian Mazza; Didier Piau

2002-01-01

450

Symmetry interplay in Brownian photomotors: From a single-molecule device to ensemble transport  

NASA Astrophysics Data System (ADS)

Unlike most of Brownian motor models in which the state of a point particle is described by a single scalar fluctuating parameter, we consider light-induced dichotomic fluctuations of electron density distributions in an extended molecule moving in the electrostatic periodic potential of a polar substrate. This model implies that the potential energy profiles of two motor states differ substantially and their symmetry is dictated by the interplay between the symmetries of the substrate potential and of molecular electronic states. As shown, a necessary condition for the occurrence of directed motion, the asymmetry of the potential energy profiles, is satisfied for (i) symmetric electron density distributions in molecules on asymmetric substrates and (ii) asymmetric electron density distributions in molecules on symmetric substrates. In the former case, the average velocity of directed motion is independent of molecular orientations and the ensemble of molecules moves as a whole, whereas in the latter case, oppositely oriented molecules move counterdirectionally thus causing the ensemble to diffuse. Using quantum chemical data for a specific organic-based photomotor as an example, we demonstrate that the behavior of molecular ensembles is controllable by switching on/off resonance laser radiation: they can be transported as a whole or separated into differently oriented molecules depending on the ratio of symmetric and antisymmetric contributions to the substrate electrostatic potential and to the molecular electron density distributions.

Dekhtyar, Marina L.; Rozenbaum, Viktor.

2012-09-01

451

The Molecule Pages database  

PubMed Central

The UCSD-Nature Signaling Gateway Molecule Pages (http://www.signaling-gateway.org/molecule) provides essential information on more than 3800 mammalian proteins involved in cellular signaling. The Molecule Pages contain expert-authored and peer-reviewed information based on the published literature, complemented by regularly updated information derived from public data source references and sequence analysis. The expert-authored data includes both a full-text review about the molecule, with citations, and highly structured data for bioinformatics interrogation, including information on protein interactions and states, transitions between states and protein function. The expert-authored pages are anonymously peer reviewed by the Nature Publishing Group. The Molecule Pages data is present in an object-relational database format and is freely accessible to the authors, the reviewers and the public from a web browser that serves as a presentation layer. The Molecule Pages are supported by several applications that along with the database and the interfaces form a multi-tier architecture. The Molecule Pages and the Signaling Gateway are routinely accessed by a very large research community.

Saunders, Brian; Lyon, Stephen; Day, Matthew; Riley, Brenda; Chenette, Emily; Subramaniam, Shankar

2008-01-01

452

Structural insights into protein arginine symmetric dimethylation by PRMT5  

PubMed Central

Symmetric and asymmetric dimethylation of arginine are isomeric protein posttranslational modifications with distinct biological effects, evidenced by the methylation of arginine 3 of histone H4 (H4R3): symmetric dimethylation of H4R3 leads to repression of gene expression, while asymmetric dimethylation of H4R3 is associated with gene activation. The enzymes catalyzing these modifications share identifiable sequence similarities, but the relationship between their catalytic mechanisms is unknown. Here we analyzed the structure of a prototypic symmetric arginine dimethylase, PRMT5, and discovered that a conserved phenylalanine in the active site is critical for specifying symmetric addition of methyl groups. Changing it to a methionine significantly elevates the overall methylase activity, but also converts PRMT5 to an enzyme that catalyzes both symmetric and asymmetric dimethylation of arginine. Our results demonstrate a common catalytic mechanism intrinsic to both symmetric and asymmetric arginine dimethylases, and show that steric constrains in the active sites play an essential role in determining the product specificity of arginine methylases. This discovery also implies a potentially regulatable outcome of arginine dimethylation that may provide versatile control of eukaryotic gene expression.

Sun, Litao; Wang, Mingzhu; Lv, Zongyang; Yang, Na; Liu, Yingfang; Bao, Shilai; Gong, Weimin; Xu, Rui-Ming

2011-01-01

453

Top Ten Technology Breakthroughs for Schools.  

ERIC Educational Resources Information Center

|Contributors discuss the top ten technologies that allow for thinking in new and innovative ways about the concept of "school": virtual learning; wireless networking; collaboration tools; digital video; Application Service Providers; handheld devices; optical networking; videoconferencing; XML; and simulations. (AEF)|

Bateman, Bill; Crystal, Jerry; Davidson, Hall; Holzberg, Carol S.; McIntire, Todd; McLester, Susan; Ohler, Jason; Rose, Ray; Shields, Jean; Warlick, David

2001-01-01

454

Top Five Lifestyle Changes to Reduce Cholesterol  

MedlinePLUS

High cholesterol Basics In-Depth Multimedia Expert Answers Resources Reprints A single copy of this article may be reprinted ... use only. Top 5 lifestyle changes to reduce cholesterol By Mayo Clinic staff Original Article: http://www. ...

455

A first top partner hunter's guide  

NASA Astrophysics Data System (ADS)

We provide a systematic effective lagrangian description of the phenomenology of the lightest top-partners in composite Higgs models. Our construction is based on symmetry, on selection rules and on plausible dynamical assumptions. The structure of the resulting simplified models depends on the quantum numbers of the lightest top partner and of the operators involved in the generation of the top Yukawa. In all cases the phenomenology is conveniently described by a small number of parameters, and the results of experimental searches are readily interpreted as a test of naturalness. We recast presently available experimental bounds on heavy fermions into bounds on top partners: LHC has already stepped well inside the natural region of parameter space.

De Simone, Andrea; Matsedonskyi, Oleksii; Rattazzi, Riccardo; Wulzer, Andrea

2013-04-01

456

Top partner probes of extended Higgs sectors  

NASA Astrophysics Data System (ADS)

Natural theories of the weak scale often include fermionic partners of the top quark. If the electroweak symmetry breaking sector contains scalars beyond a single Higgs doublet, then top partners can have sizable branching ratios to these extended Higgs sector states. In fact, top partner decays may provide the most promising discovery mode for such scalars, especially given the large backgrounds to direct and associated production. In this paper, we present a search strategy for top partner decays to a charged Higgs boson and a bottom quark, focusing on the case where the charged Higgs dominantly decays to third-generation quarks to yield a multi- b final state. We also discuss ways to extend this search to exotic neutral scalars decaying to bottom quark pairs.

Kearney, John; Pierce, Aaron; Thaler, Jesse

2013-08-01

457

Top and higgs physics at the Tevatron  

SciTech Connect

We present a summary of our experimental understanding of the top quark and discuss the significant improvements expected in Run II at the Fermilab Tevatron Collider. We also discuss prospects for a Higgs boson discovery at the Tevatron.

Pierre Savard

2002-12-23

458

Manifestations of top compositeness at colliders.  

SciTech Connect

We explore the possibility that the right-handed top quark is composite, identifying possible signatures of compositeness and how they might manifest themselves at the LHC and Tevatron. We perform a complete analysis of the dimension six modifications of the top coupling to gluons and find that cancellations among operators in the t{bar t} rate allow for very low compositeness scales, but this can be drastically improved by looking at kinematic distributions. Turning to the LHC, we examine four top production from a dimension six four-top operator and estimate the LHC with 100 fb{sup -1} collected luminosity to be sensitive to compositeness scales as high as 5 TeV.

Kumar, K.; Tait, T. M. P.; Vega-Morales, R.; High Energy Physics; Northwestern Univ.

2009-01-01

459

Finding top quarks with shower deconstruction  

NASA Astrophysics Data System (ADS)

We develop a new method for tagging jets produced by hadronically decaying top quarks. The method is an application of shower deconstruction, a maximum information approach that was previously applied to identifying jets produced by Higgs bosons that decay to bb¯. We tag an observed jet as a top jet based on a cut on a calculated variable ? that is an approximation to the ratio of the likelihood that a top jet would have the structure of the observed jet to the likelihood that a nontop QCD jet would have this structure. We find that the shower deconstruction based tagger can perform better in discriminating boosted top quark jets from QCD jets than other publicly available tagging algorithms.

Soper, Davison E.; Spannowsky, Michael

2013-03-01

460

Facile synthesis of symmetrical bis(benzhydryl)ethers using p-toluenesulfonyl chloride under solvent-free conditions  

PubMed Central

Background The benzhydryl ether moiety is widely distributed in nature and constitutes a key structural motif in numerous molecules of significant biological potential and of prospective clinical uses. Solvent-free and cost-effective facile synthesis of symmetrical bis(benzhydryl)ethers is, thus, much desirable. Results A simple and efficient method for the facile synthesis of symmetrical bis(benzhydryl)ethers directly from the corresponding benzhydrols has been developed using a catalytic amount of p-toluenesulfonyl chloride (5 mol%) at an oil bath temperature of 110°C under solvent-free conditions. Conclusions Operational simplicity, low reagent loading, high product yields, short reaction time, and solvent-free conditions are the notable advantages of the present method.

2013-01-01

461

Relation between reactivity and electrochemical oxidation reduction potentials of organomercury compounds. I. Symmetrization of substituted ethyl. cap alpha. -bromomercuriophenylacetates  

SciTech Connect

An approximate correlation equation relating the logarithms of the reaction rate constants for the symmetrization of para-substituted ethyl ..cap alpha..-bromomercuriophenylacetates simultaneously with the electrochemical reduction and oxidation potentials of these compounds was obtained on the basis of molecular orbital perturbation theory and was confirmed by experimental data. This equation makes it possible to assess the degree of concertedness of the four-center reaction with respect to the terminal atoms of the reacting fragments of molecules and the role of nucleophilic assistance in the reaction. It is concluded that the organomercury compounds, which are oxidized relatively easily and are at the same time reduced relatively easily, must be readily symmetrized.

Butin, K.P.; Rakhimov, R.D.; Reutov, O.A.

1987-10-10

462

Effect of molecular conformation on spectroscopic properties of symmetrical Schiff bases derived from 1,4-phenylenediamine  

NASA Astrophysics Data System (ADS)

The relationship between the molecular conformation and spectroscopic properties of symmetrical bis-Schiff bases was explored experimentally. Seven samples of compounds p-X-C6H4CHNC6H4NCHC6H4-p-X (X = OMe, Me, Et, Cl, F, CF3, or CN) were prepared for this study, and their crystal structures were measured by X-ray diffraction. Their ?max values in ethanol, acetonitrile, chloroform and cyclohexane solvents were measured, and their ?C(CN) values in chloroform-d were determined. The results show that the ?max is dependent on the substituents at the benzylidene ring and the dihedral angle ? of the titled molecules, and the term sin(?) is suitable to modify the substituent effects on the ?max. However, experimental investigations indicate that the dihedral angle ? has a limited effect on the values of ?C(CN). This study provides a new understanding for the molecular conformation on spectroscopic properties of symmetrical Schiff bases.

Fang, Zhengjun; Cao, Chenzhong

2013-03-01

463

Towards deterministically controlled InGaAs/GaAs lateral quantum dot molecules  

NASA Astrophysics Data System (ADS)

We report on the fabrication, detailed characterization and modeling of lateral InGaAs quantum dot molecules (QDMs) embedded in a GaAs matrix and we discuss strategies to fully control their spatial configuration and electronic properties. The three-dimensional morphology of encapsulated QDMs was revealed by selective wet chemical etching of the GaAs top capping layer and subsequent imaging by atomic force microscopy (AFM). The AFM investigation showed that different overgrowth procedures have a profound consequence on the QDM height and shape. QDMs partially capped and annealed in situ for micro-photoluminescence spectroscopy consist of shallow but well-defined quantum dots (QDs) in contrast to misleading results usually provided by surface morphology measurements when they are buried by a thin GaAs layer. This uncapping approach is crucial for determining the QDM structural parameters, which are required for modeling the system. A single-band effective-mass approximation is employed to calculate the confined electron and heavy-hole energy levels, taking the geometry and structural information extracted from the uncapping experiments as inputs. The calculated transition energy of the single QDM shows good agreement with the experimentally observed values. By decreasing the edge-to-edge distance between the two QDs within a QDM, a splitting of the electron (hole) wavefunction into symmetric and antisymmetric states is observed, indicating the presence of lateral coupling. Site control of such lateral QDMs obtained by growth on a pre-patterned substrate, combined with a technology to fabricate gate structures at well-defined positions with respect to the QDMs, could lead to deterministically controlled devices based on QDMs.

Wang, L.; Rastelli, A.; Kiravittaya, S.; Atkinson, P.; Ding, F.; Bof Bufon, C. C.; Hermannstädter, C.; Witzany, M.; Beirne, G. J.; Michler, P.; Schmidt, O. G.

2008-04-01

464

Weighing the Top Quark at CDF  

SciTech Connect

The most recent measurements of the top quark mass using data collected by the Collider Detector at Fermilab are summarized. Using datasets with sensitivities as large as 3.2 fb{sup -1}, the top quark mass is determined to be m{sub t} = 172.6+-0.9(stat.)+-1.2(syst.) GeV/c{sup 2}. Prospects for improvement of this measurement and its implications are discussed.

Sinervo, Pekka K. [Department of Physics, University of Toronto (Canada)

2010-02-10

465

Top-quark production and QCD  

NASA Astrophysics Data System (ADS)

We review theoretical calculations for top-quark production that include complete next-to-leading-order QCD corrections as well as higher-order soft-gluon corrections from threshold resummation. We discuss in detail the differences between various approaches that have appeared in the literature and review results for top-quark total cross sections and differential distributions at the Tevatron and the LHC.

Kidonakis, Nikolaos; Pecjak, Ben D.

2012-07-01

466

Top 10 CDs in School Libraries.  

ERIC Educational Resources Information Center

|Discusses results of a 1997 "CMC News" readers' survey of the top 10 CD-ROM titles used by schools. Compares results of previous surveys (1993 and 1995). Four tables and figures show number of users for each of the 10 CD-ROMs, top-10 rankings for year 1993, 1995, and 1997, increase in ownership of 7 of the 10 titles, and total respondents owning…

Clyde, Anne

1998-01-01

467

Single top quark production at the Tevatron  

SciTech Connect

The Tevatron experiments D0 and CDF have found evidence for single top quark production, based on datasets between 0.9 fb{sup -1} and 2.2 fb{sup -1}. Several different multivariate techniques are used to extract the single top quark signal out of the large backgrounds. The cross section measurements are also used to provide the first direct measurement of the CKM matrix element |V{sub tb}|.

Schwienhorst, Reinhard; /Michigan State U.

2008-05-01

468

Tools for top physics at CDF  

SciTech Connect

The authors describe here the different tools used for top physics analysis in the CDF Collaboration. In particular, they discuss how the jet energy scale, lepton identification, b tagging algorithms and the neural networks help to improve the signal to background ratio of the top sample in some cases and to reduce the dominant uncertainties in other. Results using each one of these tools are also presented.

Palencia, E.; /Fermilab

2008-07-01

469

The TopHat CMBR Anisotropy Experiment  

Microsoft Academic Search

The TopHat experiment will measure CMBR Anisotropy on angular scales from tens of degrees to 20 arcminutes using a balloon-borne, top-mounted, one meter telescope. The experiment is designed to cover a maximum range of spatial scales while minimizing susceptibility to systematic instrument errors. Two versions of the telescope are in development: one, having the traditional sweeping secondary having an three

S. Meyer

1996-01-01

470

TopOwl night vision improvements  

Microsoft Academic Search

TopOwl® is an original concept of binocular Helmet Mounted Sight and Display system (HMSD) for helicopters, where two Image Intensifier Tubes (IIT) are integrated on the headgear and optically coupled to the clear visor placed in front of the pilot's eyes. Thales recently developed a new version of its TopOwl®'s Display Module with the objective to have an HMSD capable

Olivier Lemoine; Jean Claude Ebert; Frédéric Saviot; Marie Charbonneau; Bruno Coumert

2008-01-01

471

Entanglement classes of permutation-symmetric qudit states: Symmetric operations suffice  

NASA Astrophysics Data System (ADS)

We analyze entanglement classes for permutation-symmetric states for n qudits (i.e., d-level systems), with respect to local unitary operations (LU equivalence) and stochastic local operations and classical communication (SLOCC equivalence). In both cases, we show that the search can be restricted to operations where the same local operation acts on all qudits, and we provide an explicit construction for it. Stabilizers of states in the form of one-particle operations preserving permutation symmetry are shown to provide a coarse-grained classification of entanglement classes. We prove that the Jordan form of such one-particle operators is a SLOCC invariant. We find, as representatives of those classes, a discrete set of entangled states that generalize the Greenberger-Horne-Zeilinger and W states for the many-particle qudit case. In the latter case, we introduce the excitation state as a natural generalization of the W state for d>2.

Migda?, Piotr; Rodriguez-Laguna, Javier; Lewenstein, Maciej

2013-07-01

472

Testing for Life's Molecules  

NSDL National Science Digital Library

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 ânever alive," one known to be âonce was alive,â 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.

Salter, Irene

2012-09-28

473

Probing single molecule dynamics  

SciTech Connect

The room temperature dynamics of single sulforhodamine 101 molecules dispersed on a glass surface are investigated on two different time scales with near-field optics. On the 10[sup [minus]2] - to 10[sup 2]-second time scale, intensity fluctuations in the emission from single molecules are examined with polarization measurements, providing insight into their spectroscopic properties. On the nanosecond time scale, the fluorescence lifetimes of single molecules are measured, and their excited-state energy transfer to the aluminum coating of the near-field probe is characterized. A movie of the time-resolved emission demonstrates the feasibility of fluorescence lifetime imaging with single molecule sensitivity, picosecond temporal resolution, and a spatial resolving power beyond the diffraction limit.

Xie, X.S.; Dunn, R.C. (Pacific Northwest Lab., Richland, WA (United States))

1994-07-15

474

Single-Molecule Enzymology  

SciTech Connect

Viewing a movie of an enzyme molecule made from molecular dynamics (MD) simulation, we see incredible details of molecular motions, be it a change of the conformation or the action of a chemical reaction.

Xie, Xiaoliang; Lu, H PETER.

1999-06-04

475

Measurements and searches with top quarks  

SciTech Connect

In 1995 the last missing member of the known families of quarks, the top quark, was discovered by the CDF and D0 experiments at the Tevatron, a proton-antiproton collider at Fermilab near Chicago. Until today, the Tevatron is the only place where top quarks can be produced. The determination of top quark production and properties is crucial to understand the Standard Model of particle physics and beyond. The most striking property of the top quark is its mass--of the order of the mass of a gold atom and close to the electroweak scale--making the top quark not only interesting in itself but also as a window to new physics. Due to the high mass, much higher than of any other known fermion, it is expected that the top quark plays an important role in electroweak symmetry breaking, which is the most prominent candidate to explain the mass of particles. In the Standard Model, electroweak symmetry breaking is induced by one Higgs field, producing one additional physical particle, the Higgs boson. Although various searches have been performed, for example at the Large Electron Positron Collider (LEP), no evidence for the Higgs boson could yet be found in any experiment. At the Tevatron, multiple searches for the last missing particle of the Standard Model are ongoing with ever higher statistics and improved analysis techniques. The exclusion or verification of the Higgs boson can only be achieved by combining many techniques and many final states and production mechanisms. As part of this thesis, the search for Higgs bosons produced in association with a top quark pair (t{bar t}H) has been performed. This channel is especially interesting for the understanding of the coupling between Higgs and the top quark. Even though the Standard Model Higgs boson is an attractive candidate, there is no reason to believe that the electroweak symmetry breaking is induced by only one Higgs field. In many models more than one Higgs boson are expected to exist, opening even more channels to search for charged or neutral Higgs bosons. Depending on its mass, the charged Higgs boson is expected to decay either into top quarks or be the decay product of a top quark. For masses below the top quark mass, the top decay into a charged Higgs boson and a b quark can occur at a certain rate, additionally to the decays into W bosons and a b quark. The different decays of W and charged Higgs bosons can lead to deviations of the observed final number of events in certain final states with respect to the Standard Model expectation. A global search for charged Higgs bosons in top quark pair events is presented in this thesis, resulting in the most stringent limits to-date. Besides the decay of top quarks into charged Higgs or W bosons, new physics can also show up in the quark part of the decay. While in the Standard Model the top quark decays with a rate of about 100% into a W boson and a b quark, there are models where the top quark can decay into a W boson and a non-b quark. The ratio of branching fractions in which the top quark decays into a b quark over the branching fractions in which the top quark decays into all quarks is measured as part of this thesis, yielding the most precise measurement today. Furthermore, the Standard Model top quark pair production cross section is essential to be known precisely since the top quark pair production is the main background for t{bar t}H production and many other Higgs and beyond the Standard Model searches. However, not only the search or the test of the Standard Model itself make the precise measurement of the top quark pair production cross section interesting. As the cross section is calculated with high accuracy in perturbative QCD, a comparison of the measurement to the theory expectation yields the possibility to extract the top quark mass from the cross section measurement. Although many dedicated techniques exist to measure the top quark mass, the extraction from the cross section represents an important complementary measurement. The latter is briefly discussed in this thesis and compared to direct top ma

Peters, Reinhild Yvonne; /Wuppertal U.

2008-10-01

476

Top quark physics: A tool for discoveries  

NASA Astrophysics Data System (ADS)

The top quark, the heaviest known elementary particle discovered at the Fermilab Tevatron almost twenty years ago, has taken a central role in the study of fundamental interactions. The top quark behaves differently from all other quarks due to its large mass and its correspondingly short lifetime. Its large mass suggests that it may play a special role in nature. The top quark decays before it hadronizes, passing its spin information on to its decay products. Therefore, it is possible to measure observables that depend on the top quark spin, providing a unique environment for tests of the standard model and for new physics searches. With approximately 10 fb-1 of luminosity delivered to each experiment at the Tevatron, and about 20 fb-1 collected by the ATLAS and CMS experiments at the Large Hadron Collider in the first three years of operation, top quark physics is at a turning point from first studies to precision measurements with sensitivity to new physics processes. This report summarizes the latest experimental measurements and studies of top quark properties and rare decays.

Gallinaro, Michele

2013-07-01

477

Spherically symmetric model atmospheres for late-type giant stars  

NASA Astrophysics Data System (ADS)

The ATHENA computer code was developed to model the extended atmospheres of late-type giant and supergiant stars. The atmospheres are assumed to be static, spherically symmetric and in radiative and hydrostatic equilibrium. Molecular line blanketing (for now) is handled using the simplifying assumption of mean opacity. The complete linearization method of Auer and Mihalas, adapted to spherical geometry, is used to solve the model system. The radiative transfer is solved by using variable Eddington factors to close the system of moment transfer equations, and the entire system of transfer equations plus constraints is solved efficiently by arrangement into the Rybicki block matrix form. The variable Eddington factors are calculated from the full angle-dependent formal solution of the radiative transfer problem using the impact parameter method of Hummer, Kunas. We were guided by the work of Mihalas and Hummer in their development of extended models of O stars, but our method differs in the choice of the independent variable. The radius depth scale used by Mihals and Hummer was found to fail because of the strongly temperature-dependent opacities of late-type atmospheres. Instead, we were able to achieve an exact linearization of the radius. This permitted the use of the numerically well-behaved column mass or optical depth scales. The resulting formulation is analogous to the plane-parallel complete linearization method and reduces to this method in the compact atmosphere limit. Models of M giants were calculated for Teff = 3000K and 3500K with opacities of the CN, TiO, and H2O molecules included, and the results were in general agreement with other published spherical models. These models were calculated assuming radiative equilibrium. The importance of convective energy transport was estimated by calculating the convective flux that would result from the temperature structure of the models. The standard local mixing length theory was used for this purpose. Convection was found to be important only at depths with tauRM greater than 15 for the low gravity models with log g = O, but significant out to tauRM is approximately 1 at the most transparent frequencies for the higher gravity models with log g = 2. Thus, the temperature structure of the surface layers and the emergent flux for the log g = O models should be accurately modelled but the emergent flux for the log g = 2 models may be in error by up to 5 percent at the most transparent frequencies.

Bennett, Philip Desmond

478

75 FR 30007 - Race to the Top Fund Assessment Program  

Federal Register 2010, 2011, 2012, 2013

...EDUCATION Overview Information Race to the Top Fund Assessment Program Catalog...awards for FY 2010 (NIA) for the Race to the Top Fund Assessment Program. This...either grant category under the Race to the Top Fund Assessment Program...

2010-05-28

479

A DNA primer associated with banana bunchy top virus.  

PubMed

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 heterogeneous in size. The primers were cloned, sequenced and shown to map to a region within the major common region and extend 5' of this conserved region. These primers were found to be associated with multiple components of the genome and were capable of full-length complementary strand synthesis in vitro. Interestingly, most of the cloned primers appeared to be derived from BBTV DNA-5; no function has yet been determined for the putative protein of the large ORF within this component. PMID:9018072

Hafner, G J; Harding, R M; Dale, J L

1997-02-01

480

Molecular vibrations of methane molecules in the structure I clathrate hydrate from ab initio molecular dynamics simulation  

NASA Astrophysics Data System (ADS)

Vibrational frequencies of guest molecules in clathrate hydrates reflect the molecular environment and dynamical behavior of molecules. A detailed understanding of the mechanism for the vibrational frequency changes of the guest molecules in the clathrate hydrate cages is still incomplete. In this study, molecular vibrations of methane molecules in a structure I clathrate hydrate are calculated from ab initio molecular dynamics simulation. The vibrational spectra of methane are computed by Fourier transform of autocorrelation functions, which reveal distinct separation of each vibrational mode. Calculated symmetric and asymmetric stretching vibrational frequencies of methane molecules are lower in the large cages than in the small cages (8 and 16 cm-1 for symmetric and asymmetric stretching, respectively). These changes are closely linked with the C-H bond length. The vibrational frequencies for the bending and rocking vibrational modes nearly overlap in each of the cages.

Hiratsuka, Masaki; Ohmura, Ryo; Sum, Amadeu K.; Yasuoka, Kenji

2012-01-01

481

Molecular vibrations of methane molecules in the structure I clathrate hydrate from ab initio molecular dynamics simulation.  

PubMed

Vibrational frequencies of guest molecules in clathrate hydrates reflect the molecular environment and dynamical behavior of molecules. A detailed understanding of the mechanism for the vibrational frequency changes of the guest molecules in the clathrate hydrate cages is still incomplete. In this study, molecular vibrations of methane molecules in a structure I clathrate hydrate are calculated from ab initio molecular dynamics simulation. The vibrational spectra of methane are computed by Fourier transform of autocorrelation functions, which reveal distinct separation of each vibrational mode. Calculated symmetric and asymmetric stretching vibrational frequencies of methane molecules are lower in the large cages than in the small cages (8 and 16 cm(-1) for symmetric and asymmetric stretching, respectively). These changes are closely linked with the C-H bond length. The vibrational frequencies for the bending and rocking vibrational modes nearly overlap in each of the cages. PMID:22299892

Hiratsuka, Masaki; Ohmura, Ryo; Sum, Amadeu K; Yasuoka, Kenji

2012-01-28

482

Centrifugal Distortion Analysis of a Near-Spherical Top, SO2F2: The First Determination of All Six Quartic Centrifugal Distortion Constants for an Asymmetric Top  

NASA Astrophysics Data System (ADS)

The rotational spectrum of the near-spherical top molecule SO2F2 (sulfuryl fluoride) has been investigated by microwave Fourier transform spectroscopy and by millimeter-wave spectroscopy. The ground state spectrum has been measured from 10 to 472 GHz. One of the reasons for studying this