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Sample records for symmetric top molecules

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

    SciTech Connect

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

    2008-01-01

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

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

    PubMed

    Najib, Hamid

    2013-01-01

    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

  3. Development of the Hamiltonian and transition moment operators of symmetric top molecules using the O (3) ? C? v ? C3 v group chain

    NASA Astrophysics Data System (ADS)

    El Hilali, A.; Boudon, V.; Loëte, M.

    2005-11-01

    We present a development of the Hamiltonian, dipole moment, and polarizability operators for XY 3Z molecules. These rovibrational operators are written with the aid of a tensorial formalism derived from the one already used in Dijon and adapted to the XY 3Z symmetric tops in a recent paper [A. El Hilali, V. Boudon, M. Loëte, J. Mol. Spectrosc. 234 (2005) 166-174]. We use the O (3) ? C? v ? C3 v group chain. Expressions for the matrix elements are derived for these operators.

  4. The vt=1 Rovibrational Hamiltonian for C3 v Symmetric Top Molecules Containing One Quadrupolar Nucleus: Reductions and Application to AsF 3

    NASA Astrophysics Data System (ADS)

    Harder, H.; Gerke, C.; Fusina, L.; Dréan, P.

    2002-01-01

    The reduction of the effective Hamiltonian has been derived for C3v symmetric top molecules in the vtequals;1 state with extension to nuclear quadrupole coupling. The theory has been applied to the hyperfine structures of rotational transitions observed for AsF3 (v4equals;1) [H. Bürger, J. Demaison, P. Dréan, C. Gerke, L. Halonen, H. Harder, H. Mäder, J. Radtke, and H. Ruland, J. Mol. Spectrosc.180, 85-99 (1996)]. The data have been analyzed using two reduced forms of the effective Hamiltonian which follow the reductions Q and D [E. I. Lobodenko, O. N. Sulakshina, V. I. Perevalov, and Vl. G. Tyuterev, J. Mol. Spectrosc.126, 159-170 (1987)] in the pure rovibrational case. The unitary equivalence of the derived parameter sets has been demonstrated.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

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

    E-print Network

    Saldin, Dilano

    be used to directly probe the laser-induced structure of molecules of arbitrary size with subnanometer-ray scattering studies, pro- vided that a high degree of spatial alignment is achieved.12­15 The far-field scattering pattern obtained over many x-ray pulses is then an incoherent sum of scattering patterns from

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

    SciTech Connect

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

    2014-04-07

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

  8. Rotational excitation of symmetric top molecules by collisions with atoms: Close coupling, coupled states, and effective potential calculations for NH3-He

    NASA Technical Reports Server (NTRS)

    Green, S.

    1976-01-01

    The formalism for describing rotational excitation in collisions between symmetric top rigid rotors and spherical atoms is presented both within the accurate quantum close coupling framework and also the coupled states approximation of McGuire and Kouri and the effective potential approximation of Rabitz. Calculations are reported for thermal energy NH3-He collisions, treating NH3 as a rigid rotor and employing a uniform electron gas (Gordon-Kim) approximation for the intermolecular potential. Coupled states are found to be in nearly quantitative agreement with close coupling results while the effective potential method is found to be at least qualitatively correct. Modifications necessary to treat the inversion motion in NH3 are discussed.

  9. Phase behavior of symmetric disk-coil molecules

    E-print Network

    Kim, Yongjoo

    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 ...

  10. Super Atomic Molecular Orbitals of Variably Protonated Symmetric Molecules

    NASA Astrophysics Data System (ADS)

    Latta, Tanner; Drake, Kyle; Zhang, G. P.

    2015-03-01

    The molecular structure of symmetric molecules creates conducive conditions for delocalized orbitals. The ? bonding delocalizes the valence electrons away from the individual molecules. These delocalized valence electrons allow the symmetric molecules to adapt the characteristics analogous to that of an individual atom, creating Super Atomic Molecular Orbitals, SAMOs. The symmetric molecule is then comparable to that of an individual atom with its regular atomic orbitals. When these symmetric molecules are protonated in any form, there are notable changes in the shapes of the Super Atomic Molecular Orbitals. We use the Density Functional Theory with a grid mesh method to compute the wavefunctions of those SAMOs. Then we examine the Rydberg States of these symmetric molecules through the calculated Eigenstates, and find an important trend in the filling of the SAMOs as well as relationships between variably protonated symmetric molecules. This is potentially very useful to understanding the photovoltaic effect in the fullerene- based solar cells. Support by U.S. Department of Energy No DE-FG02-06ER46304.

  11. Resonances in the heavy symmetrical top with vibrating pivot

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, S.

    2013-02-01

    In this work we consider a heavy symmetrical top whose pivot is subjected to small-amplitude, high-frequency vibrations in the vertical direction. For analytical simplicity we confine ourselves to positions of the top close to the vertical. We first apply the slow-fast separation method originally devised by Kapitza and Landau for analysing the vibrational stabilization of an inverted pendulum. This analysis yields the slow precession frequency but we see that the equations become undefined at a particular value of the vibration frequency. This breakdown is seen to correspond to a resonance and we use Euler's equations to write down the solution at the resonance. For vibration in the horizontal direction there is a resonance at more or less the same frequency as before but the dynamics at the resonance is different from the former case.

  12. Deflection of Rotating Symmetric Molecules by Inhomogeneous Fields

    E-print Network

    Erez Gershnabel; Ilya Sh. Averbukh

    2011-05-16

    We consider deflection of rotating symmetric molecules by inhomogeneous optical and static electric fields, compare results with the case of linear molecules, and find new singularities in the distribution of the scattering angle. Scattering of the prolate/oblate molecules is analyzed in detail, and it is shown that the process can be efficiently controlled by means of short and strong femtosecond laser pulses. In particular, the angular dispersion of the deflected molecules may be dramatically reduced by laser-induced molecular pre-alignment. We first study the problem by using a simple classical model, and then find similar results by means of more sophisticated methods, including the formalism of adiabatic invariants and direct numerical simulation of the Euler-Lagrange equations of motion. The suggested control scheme opens new ways for many applications involving molecular focusing, guiding, and trapping by optical and static fields.

  13. Deflection of Rotating Symmetric Molecules by Inhomogeneous Fields

    E-print Network

    Gershnabel, Erez

    2011-01-01

    We consider deflection of rotating symmetric molecules by inhomogeneous optical and static electric fields, compare results with the case of linear molecules, and find new singularities in the distribution of the scattering angle. Scattering of the prolate/oblate molecules is analyzed in detail, and it is shown that the process can be efficiently controlled by means of short and strong femtosecond laser pulses. In particular, the angular dispersion of the deflected molecules may be dramatically reduced by laser-induced molecular pre-alignment. We first study the problem by using a simple classical model, and then find similar results by means of more sophisticated methods, including the formalism of adiabatic invariants and direct numerical simulation of the Euler-Lagrange equations of motion. The suggested control scheme opens new ways for many applications involving molecular focusing, guiding, and trapping by optical and static fields.

  14. Collisional Transitions in Interstellar Asymmetric Top Molecules

    NASA Astrophysics Data System (ADS)

    Chandra, Suresh

    2012-07-01

    For the study of a molecule in interstellar space or in circumstellar envelopes of an evolved star, one has to deal with a multi-level system in the molecule. These levels are connected through radiative as well as collisional transitions. The NLTE effects in a molecule come in the picture only when collisional transitions are present. Computation of collisional rates is quite cumbersome task. Besides emission and absorption, two anomalous phenomena: (i) MASER action and (ii) Anomalous absorption (Absorption against the CMB) are shown by some molecules in interstellar space. Both of these phenomena are good examples of NLTE prevailing in the interstellar space and circumstellar envelopes of evolved stars. In the present talk, we shall discuss about the collisional transitions between rotational levels in a molecule. The collisional rate coefficients for the rotational transition J ? ? J' ?' at the kinetic temperature T, averaged over the Maxwellian distribution are C(J ? ? J' ?'|T) = \\Big(\\frac{8 k T}{? ?}\\Big)^{1/2} \\Big(\\frac{1}{k T}\\Big)^2 \\int_0^\\infty ? (J ? ? J' ?'|E) E {e}^{-E/kT} {d} E where ? is the reduced mass of the system and the cross section ?(J ? ? J' ?'|E) for the transition is \\begin{eqnarray} ? (J ? ? J' ?'|E) = \\sum_{L M M'} S(J, ?, J', ?'|L, M, M') q(L, M, M'|E) The q(L, M, M'|E) are the parameters which can be obtained from the software MOLSCAT. The spectroscopic coefficients, S ( J, ?, J', ?'|L, M, M'), depend on the wave-functions of the molecules and on the angular momentum coupling factors: S(J, ?, J', ?'|L, M, M') = \\sum_{p, p', q, q'} g^p_{J ?} g^q_{J ?} g^{p'}_{J' ?'} g^{q'}_{J' ?'} \\big \\big Here, \\big represents the Clebsch-Gorden coefficient. The g-coefficients can be obtained from laboratory analysis of the molecule and the parameters q(L, M, M'|E) can be obtained with the help of the software MOLSCAT for a known interaction potential. As an example, we shall discuss collisional rates for rotational transitions in H_2CS molecule.

  15. Towards Understanding Quantum Monodromy in Quasi-Symmetric Molecules: Fassst Rotational Spectra of CH_3NCO and CH_3NCS

    NASA Astrophysics Data System (ADS)

    Kisiel, Zbigniew; Fortman, Sarah; Medvedev, Ivan R.; Winnewisser, Manfred; De Lucia, Frank C.; Koput, Jacek

    2010-06-01

    The recent studies of the rotational spectrum of the NCNCS molecule demonstrated the success of quantum monodromy in describing the quasilinear behavior of this molecule, inclusive of the abrupt transition of spectroscopic behavior from the bent to the linear molecule regime. Similar, quasisymmetric behaviour, is known to be present in symmetric top molecules, and has been studied at lowest-J transitions for two such molecules, CH_3NCO and CH_3NCS. Further progress requires more experimental data and presently we report FASSST rotational spectra of CH_3NCO and CH_3NCS. The spectra provide practically continuous 117-376 GHz coverage and are very rich, since the ladder of excited vibrational states associated with the qusilinear bending coordinate is multiplied by the nearly free internal rotation of the methyl group. Initial stages of the analysis leading up to an analysis in an extension of the framework used for NCNCS are described. B.P.Winnewisser, et al., Phys. Rev. Lett. 95. 243002 (2005). M.Winnewisser, et al., J. Mol. Struct. 798, 1 {2006}. B.P.Winnewisser, et al., Phys. Chem. Chem. Phys. DOI:10.1039/B922023B (2010). J.Koput, J. Mol. Spectrosc. 115, 131 (1986) J.Koput, J. Mol. Spectrosc. 118, 189 (1986)

  16. Self-induced spontaneous transport of water molecules through a symmetrical nanochannel by ratchetlike mechanism

    E-print Network

    Wan, R; Li, J; Bao, J; Hu, J; Fang, H; Wan, Rongzheng; Lu, Hangjun; Li, Jinyuan; Bao, Jingdong; Hu, Jun; Fang, Haiping

    2006-01-01

    Gaining work from thermal fluctuations without external input energy is a dream for scientists but is forbidden by the second law of thermodynamics. Feynman proposed a molecular ratchet toward this direction but there are still theoretical arguments against it. Here, we revisit this classical problem by using molecular dynamics simulation to monitor water molecules confined in a carbon nanotube. A spontaneous directional transportation of water molecules was observed in this symmetrical nanochannel by a ratchetlike mechanism. This is the first ratchetlike system without any asymmetrical structure or external field, while the asymmetric ratchetlike potential solely results from the transported water molecules that form hydrogen-bonded chains among themselves. Importantly, the resulting net water fluxes reached the level of biological channel, suggesting possible adoption by life. This effect is ascribed to the exceptive structure of the water molecule; a minute change in hydrogen-bond strength dramatically aff...

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

    SciTech Connect

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

    2007-01-01

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

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

    SciTech Connect

    Chang, Bo Y.; Shin, Seokmin; Sola, Ignacio R.

    2010-12-15

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

  19. Conductance through single biphenyl molecules: symmetric and asymmetric coupling to electrodes

    PubMed Central

    Kanthasamy, Karthiga

    2015-01-01

    Summary The contacts and the chemical bonds formed between metallic electrodes and molecules determine to a large extent the conductive properties of single molecular junctions, which represent the smallest possible active elements in an electronic circuit. We therefore investigated in a comparative study, using the break junction technique (MCBJ), the conductive properties of [1,1’-biphenyl]-4,4’-dithiol (M1) and of 4’-mercapto-[1,1’-biphenyl]-4-carbonitrile (M2) between gold electrodes. As a function of electrode separation, characterized by the conductance close to 0 V, we found several plateaus of relative stability, with those close to 0.01G0 being the most pronounced. The overall conductance of symmetric and asymmetric molecules were surprisingly similar, only the range of stability was smaller for M2. While M1 yielded symmetric I–V-curves, only small asymmetries were detected for M2. These are also reflected in the comparable values for coupling parameters using the single level resonance model. The high conductance for the asymmetric molecule is interpreted as a result of coherent coupling of electronic states through the whole molecule, so that the outcome cannot be predicted just by adding conductive properties of individual molecular groups. PMID:26425419

  20. A new proposal for a uniform treatment of internal motions in symmetrical and asymmetrical five-membered ring molecules

    NASA Astrophysics Data System (ADS)

    Pyka, Jan

    1992-02-01

    A system of curvilinear coordinates for five-membered ring molecules is introduced and discussed. In this system all internal motions of any (symmetric or asymmetric) five-membered ring molecule can be treated as Large Amplitude Motions (LAMs). Specific calculations of two-dimensional (ring-puckering, ring-twisting) potential functions for cyclopentene and silacyclopentene molecules are presented. As an example of an asymmetric five-membered ring molecule 2,3-dihydrofuran is discussed. All these calculations are based on the numerical construction of the Hamiltonian for internal motions. An adiabatic approach is used for separation of LAMs from Small Amplitude Vibrations (SAVs).

  1. Analysis of the Microwave Spectrum of the Three-Top Molecule Trimethoxylmethane

    NASA Astrophysics Data System (ADS)

    Coudert, L. H.; Feng, G.; Caminati, W.

    2013-06-01

    Although many investigations about the spectrum of molecules displaying internal rotation of one or two methyl tops have been reported, there are much fewer results about the spectrum of molecules with three methyl tops. In this paper, we will deal with the microwave spectrum of trimethoxylmethane, HC(OCH_3)_3, a molecule displaying three conformers of quite different symmetry which all exhibit internal rotation of their three methyl tops. In a first step, a theoretical approach dedicated to the calculation of the rotation-torsion energy levels of a molecule with three inequivalent tops was developed. The model is based on a DVR approach; it accounts accurately for the rotation-torsion Coriolis couplings due to the torsion of each methyl top and leads to matrices which are smaller than those arising with the usual free internal rotation functions. The theoretical approach shows that internal rotation of the three tops leads to 27 tunneling sublevels, including 13 doubly degenerate ones. The statistical weights of the sublevels are 2^4, 2^5, and 2^6. The microwave spectrum of trimethoxylmethane has been recorded from to 10 to 19 GHz with the molecular beam Fourier transform spectrometer of the University of Bologna. The spectra of the TMM1, TMM2, and TMM3 conformers with C_1, C_3, and C_s symmetry, respectively, have been observed. The theoretical model has been applied to the lowest lying TMM1 conformer since it is the only one with three inequivalent methyl tops. The parameters describing the rotational energy and the rotation-torsion Coriolis couplings were obtained from the geometry of the conformer and those corresponding to height of the barriers hindering the internal rotations were retrieved through ab initio calculations. Calculated tunneling patterns were compared to experimental ones. As far as the number of tunneling components is concerned, there is a qualitative agreement between experiment and theory. However, the present calculation seems to underestimate the various tunneling splittings and this probably due to the fact that the barrier heights obtained through ab initio calculations are too high. Light and Ba?i?, J. Chem. Phys. 87 (1987) 4008.

  2. Charge symmetric dissociation of doubly ionized N{sub 2} and CO molecules

    SciTech Connect

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

    2014-01-21

    We report a comparative study of the features in dissociative double ionization by high energy electron impact of N{sub 2} and CO molecules. The ratio of cross-section of charge symmetric dissociative ionization to non-dissociative ionization (CSD-to-ND ratio) and the kinetic energy release (KER) spectra of dissociation are experimentally measured and carefully corrected for various ion transmission losses and detector inefficiencies. Given that the double ionization cross sections of these iso-electronic diatomics are very similar, the large difference in the CSD-to-ND ratios must be attributable to the differences in the evolution dynamics of the dications. To understand these differences, potential energy curves (PECs) of dications have been computed using multi-reference configuration interaction method. The Franck-Condon factors and tunneling life times of vibrational levels of dications have also been computed. While the KER spectrum of N{sub 2}{sup ++} can be readily explained by considering dissociation via repulsive states and tunneling of meta-stable states, indirect dissociation processes such as predissociation and autoionization have to be taken into account to understand the major features of the KER spectrum of CO{sup ++}. Direct and indirect processes identified on the basis of the PECs and experimental KER spectra also provide insights into the differences in the CSD-to-ND ratios.

  3. Symmetric bi-pyridyl banana-shaped molecule and its intermolecular hydrogen bonding liquid-crystalline complexes

    NASA Astrophysics Data System (ADS)

    Sui, Dan; Hou, Qiufei; Chai, Jia; Ye, Ling; Zhao, Liyan; Li, Min; Jiang, Shimei

    2008-11-01

    A new symmetric bi-pyridyl banana-shaped molecule 1,3-phenylene diisonicotinate (PDI) was designed and synthesized. Its molecular structure was confirmed by FTIR, Elemental analysis and 1H NMR. X-ray crystallographic study reveals that there is an angle of approximate 118° among the centroids of the three rings (pyridyl-phenyl-pyridyl) in each PDI molecule indicating a desired banana shape. In addition, a series of liquid crystal complexes nBA:PDI:nBA induced by intermolecular hydrogen bonding between PDI (proton acceptor) and 4-alkoxybenzoic acids (nBA, proton donor) were synthesized and characterized. The mesomorphism properties and optical textures of the complex of nBA:PDI:nBA were investigated by differential scanning calorimetry, polarizing optical microscope and X-ray diffraction.

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

    SciTech Connect

    Hansen, Jonas L.; Holmegaard, Lotte; Kalhoej, Line; Kragh, Sofie Louise; Stapelfeldt, Henrik; Filsinger, Frank; Meijer, Gerard; Kuepper, Jochen; Dimitrovski, Darko; Abu-samha, Mahmoud; Martiny, Christian Per Juul; Madsen, Lars Bojer

    2011-02-15

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

  5. Molecular assembly of highly symmetric molecules under a hydrogen bond framework controlled by alkyl building blocks: a simple approach to fine-tune nanoscale structures.

    PubMed

    Tanphibal, Pimsai; Tashiro, Kohji; Chirachanchai, Suwabun

    2015-12-23

    To date, molecular assemblies under the contribution of hydrogen bond in combination with weak interactions and their consequent morphologies have been variously reported; however, how the systematic variation of the structure can fine-tune the morphologies has not yet been answered. The present work finds an answer through highly symmetric molecules, i.e. diamine-based benzoxazine dimers. This type of molecule develops unique molecular assemblies with their networks formed by hydrogen bonds at the terminal, while, at the same time, their hydrogen bonded frameworks are further controlled by the hydrophobic segment at the center of the molecule. When this happens, slight differences in hydrophobic alkyl chain lengths (, , and ) bring a significant change to the molecular assemblies, thus resulting in tunable morphologies, i.e. spheres, needles and dendrites. The superimposition between the crystal lattice obtained from X-ray single crystal analysis and the electron diffraction pattern obtained from transmission electron microscopy allows us to identify the molecular alignment from single molecules to self-assembly until the morphologies developed. The present work, for the first time, shows the case of symmetric molecules, where the hydrophobic building block controls the hydrogen bond patterns, leading to the variation of molecular assemblies with tunable morphologies. PMID:26482133

  6. Abnormal difference between the mobilities of left- and right-twisted conformations of C6H12N2 roto-symmetrical molecules at very low temperatures

    NASA Astrophysics Data System (ADS)

    Gabuda, S. P.; Kozlova, S. G.

    2015-06-01

    We report an abnormal difference of low-temperature mobility of left-twisted and right-twisted conformations of roto symmetric molecules C6H12N2 (dabco) located in the same positions in crystal Zn2(C8H4O4)2?C6H12N2. The difference between 1H NMR (Nuclear Magnetic Resonance) spin-relaxation data for left-twisted and right-twisted molecules reaches ˜3 × 103 times at 8 K and tends to grow at lower temperatures. We argue that taking into account four-component relativistic Dirac wave functions in the vicinity of the nodal plane of dabco molecules and vacuum fluctuations due to virtual particle-antiparticle pairs can explain the changes which C6H12N2 conformations undergo at low temperatures.

  7. Abnormal difference between the mobilities of left- and right-twisted conformations of C6H12N2 roto-symmetrical molecules at very low temperatures.

    PubMed

    Gabuda, S P; Kozlova, S G

    2015-06-21

    We report an abnormal difference of low-temperature mobility of left-twisted and right-twisted conformations of roto symmetric molecules C6H12N2 (dabco) located in the same positions in crystal Zn2(C8H4O4)2?C6H12N2. The difference between (1)H NMR (Nuclear Magnetic Resonance) spin-relaxation data for left-twisted and right-twisted molecules reaches ?3 × 10(3) times at 8 K and tends to grow at lower temperatures. We argue that taking into account four-component relativistic Dirac wave functions in the vicinity of the nodal plane of dabco molecules and vacuum fluctuations due to virtual particle-antiparticle pairs can explain the changes which C6H12N2 conformations undergo at low temperatures. PMID:26093554

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

    PubMed

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

    2013-10-01

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

  9. Chaos in a semiclassical model of multiphoton excitation of spherical top molecules

    SciTech Connect

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

    1983-01-01

    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 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 in experiments) in the time dependence of the photon absorption and is not treatable in an additive way as inhomogeneous broadening. The nonconservation of the molecular angular momentum is due to the development with time of the molecular vibrational angular momentum. The degree of chaotic behavior is found to depend upon the relative size of the vibrational to pure rotational angular momenta as the excitation progresses, i.e., when vibrational angular momentum exceeds the pure rotational angular momentum we find chaos, conversely when J/sub 0/ is quite large the motion is gyroscopically stabilized and quasiperiodic. Therefore the suggested cold experiments are perhaps not so desirable.

  10. 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)

    Kodet, John; Judge, Richard H.

    2007-05-01

    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 III r 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 D 2h, D 2 and C 2v can be accommodated in this version. Only constant

  11. Trinitrotoluene explosive lights up ultrahigh Raman scattering of nonresonant molecule on a top-closed silver nanotube array.

    PubMed

    Zhou, Haibo; Zhang, Zhongping; Jiang, Changlong; Guan, Guijian; Zhang, Kui; Mei, Qingsong; Liu, Renyong; Wang, Suhua

    2011-09-15

    The highest Raman enhancement factors are obtained in a double resonance: molecular electronic resonance and plasmon resonance with a "hot spot" in surface-enhanced Raman scattering (SERS). However, for most molecules of interest the double resonance is not realized with the excitation frequencies normally used in Raman. The latter may limit the practical applications of SERS for trace analysis. Here, we report that Raman-inactive trinitrotoluene (TNT) lights up the ultrahigh Raman scattering of off-resonated p-aminobenzenethiol (PABT) through the formation of charge-transfer TNT-PABT complex on the top-closed flexible silver nanotube array. Raman hot spots can spontaneously form in a reversible way by the self-approaching of flexible nanotubes driven through the capillary force of solvent evaporation. Meanwhile, the PABT-TNT-PABT bridges between self-approaching silver nanotubes possibly form by the specific complexing and zwitterion interactions, and the resultant chromophores can absorb the visible light that matches with the incident laser and the localized surface plasmon of a silver nanotube array. The multiple spectral resonances lead to the huge enhancement of Raman signals of PABT molecules due to the presence of ultratrace TNT. The enhancement effect is repeatedly renewable by the reconstruction of molecular bridges and can selectively detect TNT with a limit of 1.5 × 10(-17) M. The results in this report provide the simple and supersensitive approach to the detection of TNT explosives and the possibility of building a robust Raman-based assay platform. PMID:21853974

  12. Effects on calculated half-widths and shifts from the line coupling for asymmetric-top molecules

    SciTech Connect

    Ma, Q.; Tipping, R. H.

    2014-06-28

    The refinement of the Robert-Bonamy formalism by considering the line coupling for linear molecules developed in our previous studies [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013); 140, 104304 (2014)] have been extended to asymmetric-top molecules. For H{sub 2}O immersed in N{sub 2} bath, the line coupling selection rules applicable for the pure rotational band to determine whether two specified lines are coupled or not are established. Meanwhile, because the coupling strengths are determined by relative importance of off-diagonal matrix elements versus diagonal elements of the operator ?iS{sub 1} ? S{sub 2}, quantitative tools are developed with which one is able to remove weakly coupled lines from consideration. By applying these tools, we have found that within reasonable tolerances, most of the H{sub 2}O lines in the pure rotational band are not coupled. This reflects the fact that differences of energy levels of the H{sub 2}O states are pretty large. But, there are several dozen strongly coupled lines and they can be categorized into different groups such that the line couplings occur only within the same groups. In practice, to identify those strongly coupled lines and to confine them into sub-linespaces are crucial steps in considering the line coupling. We have calculated half-widths and shifts for some groups, including the line coupling. Based on these calculations, one can conclude that for most of the H{sub 2}O lines, it is unnecessary to consider the line coupling. However, for several dozens of lines, effects on the calculated half-widths from the line coupling are small, but remain noticeable and reductions of calculated half-widths due to including the line coupling could reach to 5%. Meanwhile, effects on the calculated shifts are very significant and variations of calculated shifts could be as large as 25%.

  13. Effects on Calculated Half-Widths and Shifts from the Line Coupling for Asymmetric-Top Molecules

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    The refinement of the Robert-Bonamy formalism by considering the line coupling for linear molecules developed in our previous studies [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013); 140, 104304 (2014)] have been extended to asymmetric-top molecules. For H2O immersed in N2 bath, the line coupling selection rules applicable for the pure rotational band to determine whether two specified lines are coupled or not are established. Meanwhile, because the coupling strengths are determined by relative importance of off-diagonal matrix elements versus diagonal elements of the operator -iS1 -S2, quantitative tools are developed with which one is able to remove weakly coupled lines from consideration. By applying these tools, we have found that within reasonable tolerances, most of the H2O lines in the pure rotational band are not coupled. This reflects the fact that differences of energy levels of the H2O states are pretty large. But, there are several dozen strongly coupled lines and they can be categorized into different groups such that the line couplings occur only within the same groups. In practice, to identify those strongly coupled lines and to confine them into sub-linespaces are crucial steps in considering the line coupling. We have calculated half-widths and shifts for some groups, including the line coupling. Based on these calculations, one can conclude that for most of the H2O lines, it is unnecessary to consider the line coupling. However, for several dozens of lines, effects on the calculated half-widths from the line coupling are small, but remain noticeable and reductions of calculated half-widths due to including the line coupling could reach to 5%. Meanwhile, effects on the calculated shifts are very significant and variations of calculated shifts could be as large as 25%.

  14. Generalized Vibrational Perturbation Theory for Rotovibrational Energies of Linear, Symmetric and Asymmetric Tops: Theory, Approximations, and Automated Approaches to Deal with Medium-to-Large Molecular Systems

    PubMed Central

    Piccardo, Matteo; Bloino, Julien; Barone, Vincenzo

    2015-01-01

    Models going beyond the rigid-rotor and the harmonic oscillator levels are mandatory for providing accurate theoretical predictions for several spectroscopic properties. Different strategies have been devised for this purpose. Among them, the treatment by perturbation theory of the molecular Hamiltonian after its expansion in power series of products of vibrational and rotational operators, also referred to as vibrational perturbation theory (VPT), is particularly appealing for its computational efficiency to treat medium-to-large systems. Moreover, generalized (GVPT) strategies combining the use of perturbative and variational formalisms can be adopted to further improve the accuracy of the results, with the first approach used for weakly coupled terms, and the second one to handle tightly coupled ones. In this context, the GVPT formulation for asymmetric, symmetric, and linear tops is revisited and fully generalized to both minima and first-order saddle points of the molecular potential energy surface. The computational strategies and approximations that can be adopted in dealing with GVPT computations are pointed out, with a particular attention devoted to the treatment of symmetry and degeneracies. A number of tests and applications are discussed, to show the possibilities of the developments, as regards both the variety of treatable systems and eligible methods. © 2015 Wiley Periodicals, Inc. PMID:26345131

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  16. Polymer-facilitated low temperature fusing of spray-coated silver nanowire networks as transparent top and bottom electrodes in small molecule organic photovoltaics (Presentation Recording)

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    Networks of silver nanowires (AgNWs) are promising candidates for transparent conducting electrodes in organic photovoltaics (OPV), as they achieve similar performance as the commonly used indium tin oxide (ITO) at lower cost and increased flexibility. The initial sheet resistance (Rs) of AgNW electrodes typically needs to be reduced by a post-annealing step (90 min@200 °C), being detrimental for processing on polymeric substrates. We present novel low temperature-based methods to integrate AgNWs in organic small molecule-based photovoltaics, either as transparent and highly conductive bottom-electrode or, for the first time, as spray-coated AgNW top-electrode. The bottom-electrodes are prepared by organic matrix assisted low-temperature fusing. Here, selected polymers are coated below the AgNWs to increase the interaction between NWs and substrate. In comparison to networks without these polymeric sublayers, the Rs is reduced by two orders of magnitude. AgNW top-electrodes are realized by dispersing modified high-quality AgNWs in inert solvents, which do not damage small molecule layers. Accordingly, our AgNW dispersion can be spray-coated onto all kind of OPV devices. Both bottom- and top-electrodes show a Rs of <11 ?/ at >87 % transparency directly after spray-coating at very low substrate temperatures of <80 °C. We also demonstrate the implementation of our AgNW electrodes in organic solar cells. The corresponding devices show almost identical performance compared to organic solar cells exploiting ITO as bottom or thermally evaporated thin-metal as top-electrode.

  17. The bending triad of the quasi-spherical top molecule SO 2F 2 in the 550 cm -1 region

    NASA Astrophysics Data System (ADS)

    Rotger, M.; Boudon, V.; Loëte, M.; Zvereva-Loëte, N.; Margulès, L.; Demaison, J.; Merke, I.; Hegelund, F.; Bürger, H.

    2006-08-01

    The analysis of the ?3/ ?7/ ?9 bending triad of SO 2F 2 has been recently performed with the Watson's Hamiltonian up to octic terms employing 79 rovibrational parameters but including only the first order Coriolis interaction terms, fixed to ab initio values [H. Bürger, J. Demaison, F. Hegelund, L. Margulès, I. Merke, J. Mol. Struct. 612 (2002) 133-141]. Since SO 2F 2 is a quasi-spherical top, it can also be considered as derived from the SO42- sulfate ion. We have thus developed a new tensorial formalism in the O (3) ? Td ? C2 v group chain [M. Rotger, V. Boudon, M. Loëte, J. Mol. Spectrosc. 216 (2002) 297-307]. This approach allows a systematic development of rovibrational interactions and makes global analyses easier to perform even for complex polyad systems. We present here an application of this model to the analysis of the bending triad, with the same set of microwave assignments and almost the same set of infrared assignments as in the previous study of Bürger et al. It appears that we need to expand our Hamiltonian to a lower degree than the "classical" one (six instead of eight) when including also the second order Coriolis interactions. Our fit does not include more parameters. Furthermore, all of them are determined and the standard deviation of the rotational transitions is twice smaller. The analysis has been performed thanks to the C 2 v TDS program suite, which is freely available at the URL: http://www.u-bourgogne.fr/LPUB/c2vTDS.html.

  18. Organometallic complexes of bulky, optically active, C3-symmetric tris(4S-isopropyl-5,5-dimethyl-2-oxazolinyl)phenylborate (ToP *)

    DOE PAGESBeta

    Xu, Songchen; Magoon, Yitzhak; Reinig, Regina R.; Schmidt, Bradley M.; Ellern, Arkady; Sadow, Aaron D.

    2015-07-16

    A bulky, optically active monoanionic scorpionate ligand, tris(4S-isopropyl-5,5-dimethyl-2-oxazolinyl)phenylborate (ToP*), is synthesized from the naturally occurring amino acid l-valine as its lithium salt, Li[ToP*] (1). That compound is readily converted to the thallium complex Tl[ToP*] (2) and to the acid derivative H[ToP*] (3). Group 7 tricarbonyl complexes ToP*M(CO)3 (M = Mn (4), Re (5)) are synthesized by the reaction of MBr(CO)5 and Li[ToP*] and are crystallographically characterized. The ?CO bands in their infrared spectra indicate that ? back-donation in the rhenium compounds is greater with ToP* than with non-methylated tris(4S-isopropyl-2-oxazolinyl)phenylborate (ToP). The reaction of H[ToP*] and ZnEt2 gives ToP*ZnEt (6), whilemore »ToP*ZnCl (7) is synthesized from Li[ToP*] and ZnCl2. The reaction of ToP*ZnCl and KOtBu followed by addition of PhSiH3 provides the zinc hydride complex ToP*ZnH (8). In this study, compound 8 is the first example of a crystallographically characterized optically active zinc hydride. We tested its catalytic reactivity in the cross-dehydrocoupling of silanes and alcohols, which provided Si-chiral silanes with moderate enantioselectivity.« less

  19. Rotational spectroscopy as a tool to investigate interactions between vibrational polyads in symmetric top molecules: Low-lying states v(8) <= 2 of methyl cyanide, CH3CN

    SciTech Connect

    Muller, H. S.; Brown, Linda R.; Drouin, B. J.; Pearson, J. C.; Kleiner, Isabelle; Sams, Robert L.; Sung, Keeyoon; Ordu, Matthias H.; Lewen, Frank

    2015-06-01

    Rotational and rovibrational spectra of methyl cyanide were recorded to analyze interactions in low-lying vibrational states and to construct line lists for radio astronomical observations as well as for infrared spectroscopic investigations of planetary atmospheres. The rotational spectra cover large portions of the 36-1627 GHz region. In the infrared (IR), a spectrum was recorded for this study in the region of 2v(8) around 717 cm(-1) with assignments covering 684-765 cm-1. Additional spectra in the vs region were used to validate the analysis.

  20. Rotational Spectroscopy as a Tool to Investigate Interactions Between Vibrational Polyads in Symmetric Top Molecules: Low-Lying States v_8 ? 2 OF Methyl Cyanide

    NASA Astrophysics Data System (ADS)

    Müller, Holger S. P.; Ordu, Matthias H.; Lewen, Frank; Brown, Linda; Drouin, Brian; Pearson, John; Sung, Keeyoon; Kleiner, Isabelle; Sams, Robert

    2015-06-01

    Rotational and rovibrational spectra of methyl cyanide were recorded to analyze interactions in low-lying vibrational states and to construct line lists for radio astronomical observations as well as for infrared spectroscopic investigations of planetary atmospheres. The rotational spectra cover large portions of the 36-1627~GHz region. In the infrared (IR), a spectrum was recorded for this study in the region of 2?_8 around 717~cm-1 with assignments covering 684-765~cm-1. Additional spectra in the ? _8 region were used to validate the analysis. Using ? _8 data as well as spectroscopic parameters for v_4 = 1, v_7 = 1, and v_8 = 3 from previous studies, we analyzed rotational data involving v = 0, v_8 = 1, and v_8 = 2 up to high J and K quantum numbers. We analyzed a strong ? v_8 = ± 1, ? K = 0, ? l = ±3 Fermi resonance between v_8 = 1-1 and v_8 = 2+2 at K = 14 and obtained preliminary results for two further Fermi resonances between v_8 = 2 and 3. We also found resonant ? v_8 = ± 1, ? K = ? 2, ? l = ± 1 interactions between v_8 = 1 and 2 and present the first detailed analysis of such a resonance between v_8 = 0 and 1. We discuss the impact of this analysis on the v_8 = 1 and 2 as well as on the axial v = 0 parameters and compare selected CH_3CN parameters with those of CH_3CCH and CH_3NC. We evaluated transition dipole moments of ? _8, 2? _8 - ? _8, and 2? _8 for remote sensing in the IR. Part of this work was carried out at the Jet Propulsion Laboratory under contract with the National Aeronautics and Space Administration. M. Koivusaari et al., J. Mol. Spectrosc. 152 (1992) 377-388. A.-M. Tolonen et al., J. Mol. Spectrosc. 160 (1993) 554-565.

  1. Rigid rotators. [deriving the time-independent energy states associated with rotational motions of the molecule

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The two-particle, steady-state Schroedinger equation is transformed to center of mass and internuclear distance vector coordinates, leading to the free particle wave equation for the kinetic energy motion of the molecule and a decoupled wave equation for a single particle of reduced mass moving in a spherical potential field. The latter describes the vibrational and rotational energy modes of the diatomic molecule. For fixed internuclear distance, this becomes the equation of rigid rotator motion. The classical partition function for the rotator is derived and compared with the quantum expression. Molecular symmetry effects are developed from the generalized Pauli principle that the steady-state wave function of any system of fundamental particles must be antisymmetric. Nuclear spin and spin quantum functions are introduced and ortho- and para-states of rotators, along with their degeneracies, are defined. Effects of nuclear spin on entropy are deduced. Next, rigid polyatomic rotators are considered and the partition function for this case is derived. The patterns of rotational energy levels for nonlinear molecules are discussed for the spherical symmetric top, for the prolate symmetric top, for the oblate symmetric top, and for the asymmetric top. Finally, the equilibrium energy and specific heat of rigid rotators are derived.

  2. Symmetric Skyrmions

    SciTech Connect

    Battye, R.A.; Sutcliffe, P.M.

    1997-07-01

    We present candidates for the global minimum energy solitons of charge 5 to 9 in the Skyrme model generated using sophisticated numerical algorithms. The solitons found are particularly symmetric; for example, the charge seven skyrmion has icosahedral symmetry, and the shapes are shown to fit a remarkable sequence defined by a geometric energy minimization (GEM) rule. {copyright} {ital 1997} {ital The American Physical Society}

  3. Two dimensional symmetric correlation functions of the S-circumflex operator and two dimensional Fourier transforms: Considering the line coupling for P and R lines of linear molecules

    SciTech Connect

    Ma, Q.; Tipping, R. H.

    2014-03-14

    The refinement of the Robert-Bonamy (RB) formalism by considering the line coupling for isotropic Raman Q lines of linear molecules developed in our previous study [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)] has been extended to infrared P and R lines. In these calculations, the main task is to derive diagonal and off-diagonal matrix elements of the Liouville operator iS{sub 1} ? S{sub 2} introduced in the formalism. When one considers the line coupling for isotropic Raman Q lines where their initial and final rotational quantum numbers are identical, the derivations of off-diagonal elements do not require extra correlation functions of the S-circumflex operator and their Fourier transforms except for those used in deriving diagonal elements. In contrast, the derivations for infrared P and R lines become more difficult because they require a lot of new correlation functions and their Fourier transforms. By introducing two dimensional correlation functions labeled by two tensor ranks and making variable changes to become even functions, the derivations only require the latters’ two dimensional Fourier transforms evaluated at two modulation frequencies characterizing the averaged energy gap and the frequency detuning between the two coupled transitions. With the coordinate representation, it is easy to accurately derive these two dimensional correlation functions. Meanwhile, by using the sampling theory one is able to effectively evaluate their two dimensional Fourier transforms. Thus, the obstacles in considering the line coupling for P and R lines have been overcome. Numerical calculations have been carried out for the half-widths of both the isotropic Raman Q lines and the infrared P and R lines of C{sub 2}H{sub 2} broadened by N{sub 2}. In comparison with values derived from the RB formalism, new calculated values are significantly reduced and become closer to measurements.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  5. Symmetric Cryptography Asymmetric Cryptography

    E-print Network

    Ramkumar, Mahalingam

    Outline Symmetric Cryptography Asymmetric Cryptography Key Management Network Security Cryptography Symmetric Cryptography Asymmetric Cryptography Key Management Network Security 1 Symmetric Cryptography Symmetric Cryptography Overview Block Cipher Modes Multiple Encryption Hash Functions Message Authentication

  6. ATP molecule ATP molecule

    E-print Network

    ATP molecule 9 ATP molecule 8 Autumn 2003 · Vol. 1 No. 2 · inSiDE inSiDE · Vol. 1 No. 2 · Autumn with adenosine 5`-triphosphate (ATP). ATP is the most important energy carrier in cellular metabolism, and each human being produces its own weight in ATP every day. The ATP molecule is shown in Figure 1, where

  7. Aspects of Quantum Computing with Polar Paramagnetic Molecules

    NASA Astrophysics Data System (ADS)

    Karra, Mallikarjun; Friedrich, Bretislav

    2015-05-01

    Since the original proposal by DeMille, arrays of optically trapped ultracold polar molecules have been considered among the most promising prototype platforms for the implementation of a quantum computer. The qubit of a molecular array is realized by a single dipolar molecule entangled via its dipole-dipole interaction with the rest of the array's molecules. A superimposed inhomogeneous electric field precludes the quenching of the body-fixed dipole moments by rotation and a time dependent external field controls the qubits to perform gate operations. Much like our previous work in which we considered the simplest cases of a polar 1 ? and a symmetric top molecule, here we consider a X2?3 / 2 polar molecule (exemplified by the OH radical) which, by virtue of its nonzero electronic spin and orbital angular momenta, is, in addition, paramagnetic. We demonstrate entanglement tuning by evaluating the concurrence (and the requisite frequencies needed for gate operations) between two such molecules in the presence of varying electric and magnetic fields. Finally, we discuss the conditions required for achieving qubit addressability (transition frequency difference, ?? , as compared with the concomitant Stark and Zeeman broadening) and high fidelity. International Max Planck Research School - Functional Interfaces in Physics and Chemistry.

  8. Tensorial Formalism for Rovibronic Spectroscopy of C3v Molecules Spectroscopy of XY3Z (C3v) Molecules with AN Even or Odd Number of Electrons: a Tensorial Formalism Adapted to the SU(2)otimes CIsupset C? vSsupset C3vS Group Chain

    NASA Astrophysics Data System (ADS)

    Hilali, A. El; Boudon, V.

    2010-06-01

    In molecular spectroscopy, it is often considered that sophisticated group theoretical and tensorial formalism methods are only really useful for spherical top (i.e. highly symmetrical) molecules, for which they have proven their high efficiency. Consequently, it is usually admitted that symmetric and asymmetric tops (i.e. lower symmetry) species should be treated using more ``conventional'' methods. However, some key elements of the formalism developed in our group for tetrahedral or octahedral molecules can be used with great profit even for less symmetrical systems: the ability of performing systematic developments of all rovibrational interactions in case of complex polyads and the so-called ``vibrational extrapolation'' which makes global analyses much easier. Firstly, we present the development of a tensorial formalism adapted to the study of XY3Z type molecules which possess integer angular momenta (i.e. in a singlet electronic state) by using the O(3)supset C? vsupset C3v chain. We present also the C3v TDS(C3v Top Data System) software for spectrum simulation dedicated to the study of symmetric-top molecules belonging to the C3v point group. Secondly, we present the development of a tensorial formalism adapted to the study of XY_3Z type open-shell species which possess half-integer angular momenta by using the SU(2)otimes C_Isupset C? vSsupset C3vS group chain A. El Hilali, V. Boudon and M. Loete, J. Mol. Spectrosc., 234, 176-181 (2005). A. El Hilali, Ch. Wenger, V. Boudon and M. Loete, J. Quant. Spectrosc. Radiat. Transfert., accepted (2010). A. El Hilali, V. Boudon and M. Loete, J. Mol. Spectrosc., 239, 41-50 (2006). A. El Hilali, V. Boudon and M. Loete, J. Mol. Spectrosc., 253, 92-98 (2009). A. El Hilali, V. Boudon and M. Loete, J. Mol. Spectrosc., 234, 131-121 (2005).

  9. Symmetric Cryptography Asymmetric Cryptography

    E-print Network

    Ramkumar, Mahalingam

    Outline Trust Symmetric Cryptography Asymmetric Cryptography Key Management Network Security Cryptography - A Review Mahalingam Ramkumar Mississippi State University, MS September 22, 2006 Ramkumar Review #12;Outline Trust Symmetric Cryptography Asymmetric Cryptography Key Management Network Security 1

  10. Top studies

    SciTech Connect

    T. Dorigo

    2003-01-02

    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.

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

    SciTech Connect

    Ma, Yong-Tao; Li, Hui; Zeng, Tao

    2014-06-07

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

  12. Architectural Tops

    ERIC Educational Resources Information Center

    Mahoney, Ellen

    2010-01-01

    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…

  13. Wave Engine Topping Cycle Assessment

    NASA Technical Reports Server (NTRS)

    Welch, Gerard E.

    1996-01-01

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

  14. Polyatomic molecule vibrations

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Polyatomic molecule vibrations are analyzed as harmonic vibrations along normal coordinates. The energy eigenvalues are found for linear and nonlinear symmetric triatomic molecules for valence bond models of the potential function with arbitrary coupling coefficients; such models can usually be fitted to observed energy levels with reasonably good accuracy. Approximate normal coordinates for the H2O molecule are discussed. Degenerate vibrational modes such as occur in CO2 are analyzed and expressions for Fermi resonance between close-lying states of the same symmetry are developed. The bending modes of linear triatomic molecules are expressed in terms of Laguerre polynomials in cylindrical coordinates as well as in terms of Hermite polynomials in Cartesian coordinates. The effects of large-amplitude bending such as occur in the C3 molecule are analyzed, along with anharmonic effects, which split the usually degenerate bending mode energy levels. Finally, the vibrational frequencies, degeneracies, and symmetry properties of XY3, X2Y2, and XY4 type molecules are discussed.

  15. PT-symmetric strings

    SciTech Connect

    Amore, Paolo; Fernández, Francisco M.; Garcia, Javier; Gutierrez, German

    2014-04-15

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

  16. Symmetric image registration.

    PubMed

    Rogelj, Peter; Kovacic, Stanislav

    2006-06-01

    This paper presents an original non-rigid image registration approach, which tends to improve the registration by establishing a symmetric image interdependence. In order to gather more information about the image transformation it measures the image similarity in both registration directions. The presented solution is based on the interaction between the images involved in the registration process. Images interact through forces, which according to Newton's action-reaction law form a symmetric relationship. These forces may transform both of the images, although in our implementation one of the images remains fixed. The experiments performed to demonstrate the advantages of the symmetric registration approach involve the registration of simple objects, the recovery of synthetic deformation, and the inter-patient registration of real images of the head. The results show that the symmetric approach improves both the registration consistency and the registration correctness. PMID:15896998

  17. Symmetrical gait descriptions

    NASA Astrophysics Data System (ADS)

    Dunajewski, Adam; Dusza, Jacek J.; Rosado Muñoz, Alfredo

    2014-11-01

    The article presents a proposal for the description of human gait as a periodic and symmetric process. Firstly, the data for researches was obtained in the Laboratory of Group SATI in the School of Engineering of University of Valencia. Then, the periodical model - Mean Double Step (MDS) was made. Finally, on the basis of MDS, the symmetrical models - Left Mean Double Step and Right Mean Double Step (LMDS and RMDS) could be created. The method of various functional extensions was used. Symmetrical gait models can be used to calculate the coefficients of asymmetry at any time or phase of the gait. In this way it is possible to create asymmetry, function which better describes human gait dysfunction. The paper also describes an algorithm for calculating symmetric models, and shows exemplary results based on the experimental data.

  18. Noncommutative spherically symmetric spaces

    SciTech Connect

    Murray, Sean; Govaerts, Jan

    2011-01-15

    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.

  19. Symmetric continued fractions

    SciTech Connect

    Panprasitwech, Oranit; Laohakosol, Vichian; Chaichana, Tuangrat

    2010-11-11

    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 {kappa}-fold symmetry, the notion of {kappa}-duplicating symmetric continued fractions is investigated using a modification of the 1995 technique due to Clemens, Merrill and Roeder.

  20. Molecule nanoweaver

    DOEpatents

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

    2009-03-10

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

  1. Tops and Writhing DNA

    E-print Network

    Joseph Samuel; Supurna Sinha

    2010-11-30

    The torsional elasticity of semiflexible polymers like DNA is of biological significance. A mathematical treatment of this problem was begun by Fuller using the relation between link, twist and writhe, but progress has been hindered by the non-local nature of the writhe. This stands in the way of an analytic statistical mechanical treatment, which takes into account thermal fluctuations, in computing the partition function. In this paper we use the well known analogy with the dynamics of tops to show that when subjected to stretch and twist, the polymer configurations which dominate the partition function admit a local writhe formulation in the spirit of Fuller and thus provide an underlying justification for the use of Fuller's "local writhe expression" which leads to considerable mathematical simplification in solving theoretical models of DNA and elucidating their predictions. Our result facilitates comparison of the theoretical models with single molecule micromanipulation experiments and computer simulations.

  2. Yangian symmetric correlators

    NASA Astrophysics Data System (ADS)

    Chicherin, D.; Kirschner, R.

    2013-12-01

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

  3. PT-symmetric kinks

    SciTech Connect

    Souza Dutra, A. de; Santos, V. G. C. S. dos; Amaro de Faria, A. C. Jr.

    2007-06-15

    Some kinks for non-Hermitian quantum field theories in 1+1 dimensions are constructed. A class of models where the soliton energies are stable and real are found. Although these kinks are not Hermitian, they are symmetric under PT transformations.

  4. Quantum symmetric spaces

    E-print Network

    Donin, J; Donin, J; Shnider, S

    1994-01-01

    Let G be a semisimple Lie group, {\\frak g} its Lie algebra. For any symmetric space M over G we construct a new (deformed) multiplication in the space A of smooth functions on M. This multiplication is invariant under the action of the Drinfeld--Jimbo quantum group U_h{\\frak g} and is commutative with respect to an involutive operator \\tilde{S}: A\\otimes A \\to A\\otimes A. Such a multiplication is unique. Let M be a k\\"{a}hlerian symmetric space with the canonical Poisson structure. Then we construct a U_h{\\frak g}-invariant multiplication in A which depends on two parameters and is a quantization of that structure.

  5. Symmetric modular torsatron

    DOEpatents

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

    1984-01-01

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

  6. Walking Molecules 

    E-print Network

    Symes, Mark D

    2009-01-01

    Inspired by the motor protein kinesin, an ambitious and unprecedented mimic is proposed – a synthetic molecular motor that can walk. This thesis aims to explain the basic principles which define such walking molecules, ...

  7. Interstellar Molecules

    ERIC Educational Resources Information Center

    Solomon, Philip M.

    1973-01-01

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

  8. Charmonium molecules?

    SciTech Connect

    Valcarce, A.; Fernandez-Carames, T.; Vijande, J.

    2010-08-05

    In this talk we present some recent studies of multiquark components in the charmonium sector. We study the possible existence of compact four quark-states and meson-meson molecules in the charmonium spectroscopy.

  9. Static cylindrically symmetric spacetimes

    E-print Network

    Mikael Fjallborg

    2007-03-04

    We prove existence of static solutions to the cylindrically symmetric Einstein-Vlasov system, and we show that the matter cylinder has finite extension. The same results are also proved for a quite general class of equations of state for perfect fluids coupled to the Einstein equations, extending the class of equations of state considered in \\cite{BL}. We also obtain this result for the Vlasov-Poisson system.

  10. N>=2 symmetric superpolynomials

    E-print Network

    L. Alarie-Vézina; L. Lapointe; P. Mathieu

    2015-11-16

    The theory of symmetric functions has been extended to the case where each variable is paired with an anticommuting one. The resulting expressions, dubbed superpolynomials, provide the natural N=1 supersymmetric version of the classical bases of symmetric functions. Here we consider the case where two independent anticommuting variables are attached to each ordinary variable. The N=2 super-version of the monomial, elementary, homogeneous symmetric functions, as well as the power sums, are then constructed systematically (using an exterior-differential formalism for the multiplicative bases), these functions being now indexed by a novel type of superpartitions. Moreover, the scalar product of power sums turns out to have a natural N=2 generalization which preserves the duality between the monomial and homogeneous bases. All these results are then generalized to an arbitrary value of N. Finally, for N=2, the scalar product and the homogenous functions are shown to have a one-parameter deformation, a result that prepares the ground for the yet-to-be-defined N=2 Jack superpolynomials.

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

    E-print Network

    Farhad Ali

    2014-12-30

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

  12. Top physics at CDF

    SciTech Connect

    Julia Thom

    2004-06-24

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

  13. Tevatron top physics

    SciTech Connect

    Wagner-Kuhr, Jeannine; /Karlsruhe U.

    2009-04-01

    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.

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

    SciTech Connect

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

    2014-12-29

    Using the pulses of terahertz free electron laser and ultra-fast Schottky diode detectors, we observed the coherent transients within a free induction decay of gaseous nitrogen dioxide NO{sub 2}. The laser excited different sub-bands of rotation spectra of NO{sub 2} containing about 50–70 lines. The free induction signal continued more than 30?ns and consisted of many echo-like bursts duration about 0.2?ns. Unlike the similar effect observed previously for linear and symmetric top molecules, the sequence of echo bursts is not periodic. The values for delay of individual echo are stable, and the set of these delays can be considered as a “molecular fingerprint” in the time domain.

  15. Chem 791 Molecular Spectroscopy Spring 2008 Chemistry 791

    E-print Network

    . ­ Harmonic expansion of potential. Normal modes. ­ FG-matrix formalism. ­ Symmetries, transition dipoles dependence of rotational constants. ­ Nonlinear molecules. Symmetric tops. Near-symmetric tops. Asymmetric

  16. Optimal symmetric flight studies

    NASA Technical Reports Server (NTRS)

    Weston, A. R.; Menon, P. K. A.; Bilimoria, K. D.; Cliff, E. M.; Kelley, H. J.

    1985-01-01

    Several topics in optimal symmetric flight of airbreathing vehicles are examined. In one study, an approximation scheme designed for onboard real-time energy management of climb-dash is developed and calculations for a high-performance aircraft presented. In another, a vehicle model intermediate in complexity between energy and point-mass models is explored and some quirks in optimal flight characteristics peculiar to the model uncovered. In yet another study, energy-modelling procedures are re-examined with a view to stretching the range of validity of zeroth-order approximation by special choice of state variables. In a final study, time-fuel tradeoffs in cruise-dash are examined for the consequences of nonconvexities appearing in the classical steady cruise-dash model. Two appendices provide retrospective looks at two early publications on energy modelling and related optimal control theory.

  17. Minimally symmetric Higgs boson

    NASA Astrophysics Data System (ADS)

    Low, Ian

    2015-06-01

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

  18. Top quark physics

    SciTech Connect

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

    2000-03-24

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

  19. Tensorial development of the rovibronic Hamiltonian and dipole moment operators for XY 3Z molecules with a degenerate electronic state: Preliminary application to the CH 3O radical

    NASA Astrophysics Data System (ADS)

    El Hilali, A.; Boudon, V.; Loëte, M.

    2009-02-01

    We present a development of the Hamiltonian and transition moment operators of XY 3Z (C3v) symmetric tops molecules in a degenerate electronic state with the aid of a tensorial formalism developed in a recent paper [A. El Hilali, V. Boudon, M. Loëte, J. Mol. Spectrosc. 239 (2006) 41-50]. Electronic operators are defined from group theory properties. They provide a new approach to build an effective rovibronic Hamiltonian as well as an effective dipole moment operator for rovibronic transition of XY 3Z molecules. This model is studied qualitatively thanks to the tensorial algebra properties. Expressions of the matrix elements are derived for these operators. A first simple application to the ground electronic state of CH 3O is proposed as an illustrative example.

  20. Top Physics at LHC

    E-print Network

    M. Vander Donckt; for the CMS; ATLAS Collaborations

    2008-05-21

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

  1. Spherical Tippe Tops

    ERIC Educational Resources Information Center

    Cross, Rod

    2013-01-01

    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…

  2. Dare We Teach Tops?

    ERIC Educational Resources Information Center

    Featonby, David

    2010-01-01

    "Tops" are mentioned in classical literature and references are even found in the ancient world. For many children a top is one of the first mechanical toys that they play with by themselves, yet a full appreciation of their motion is rare. My hope is that this article will stimulate the reader's interest in tops, will help with the first stages…

  3. Some symmetric boundary value problems and non-symmetric solutions

    NASA Astrophysics Data System (ADS)

    Arioli, Gianni; Koch, Hans

    2015-07-01

    We consider the equation - ?u = wf? (u) on a symmetric bounded domain in Rn with Dirichlet boundary conditions. Here w is a positive function or measure that is invariant under the (Euclidean) symmetries of the domain. We focus on solutions u that are positive and/or have a low Morse index. Our results are concerned with the existence of non-symmetric solutions and the non-existence of symmetric solutions. In particular, we construct a solution u for the disk in R2 that has index 2 and whose modulus | u | has only one reflection symmetry. We also provide a corrected proof of [12, Theorem 1].

  4. Top Tagging at ATLAS

    E-print Network

    Caudron, Julien; The ATLAS collaboration

    2015-01-01

    Top quark particles play an important role in many beyond-the-standard-model scenarios. When produced by a massive new particle, the top quark will have a very high transverse momentum, and will be referred to as boosted top. In this regime, the study of the substructure of the large radius jet that fully contains the hadronic decay products is more efficient than the resolved reconstruction. The algorithms that identify these decays are called top-taggers. This poster presents the different top-tagging techniques used in ATLAS.

  5. Conformally symmetric traversable wormholes

    SciTech Connect

    Boehmer, Christian G.; Harko, Tiberiu; Lobo, Francisco S. N.

    2007-10-15

    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.

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

    NASA Astrophysics Data System (ADS)

    Hefferlin, R.; Barrow, J.

    2014-11-01

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

  7. HUBBLE'S TOP TEN GRAVITATIONAL LENSES

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The NASA Hubble Space Telescope serendipitous survey of the sky has uncovered exotic patterns, rings, arcs and crosses that are all optical mirages produced by a gravitational lens, nature's equivalent of having giant magnifying glass in space. Shown are the top 10 lens candidates uncovered in the deepest 100 Hubble fields. Hubble's sensitivity and high resolution allow it to see faint and distant lenses that cannot be detected with ground-based telescopes whose images are blurred by Earth's atmosphere. [Top Left] - HST 01248+0351 is a lensed pair on either side of the edge-on disk lensing galaxy. [Top Center] - HST 01247+0352 is another pair of bluer lensed source images around the red spherical elliptical lensing galaxy. Two much fainter images can be seen near the detection limit which might make this a quadruple system. [Top Right] - HST 15433+5352 is a very good lens candidate with a bluer lensed source in the form of an extended arc about the redder elliptical lensing galaxy. [Middle Far Left] - HST 16302+8230 could be an 'Einstein ring' and the most intriguing lens candidate. It has been nicknamed the 'the London Underground' since it resembles that logo. [Middle Near Left] - HST 14176+5226 is the first, and brightest lens system discovered in 1995 with the Hubble telescope. This lens candidate has now been confirmed spectroscopically using large ground-based telescopes. The elliptical lensing galaxy is located 7 billion light-years away, and the lensed quasar is about 11 billion light-years distant. [Middle Near Right] - HST 12531-2914 is the second quadruple lens candidate discovered with Hubble. It is similar to the first, but appears smaller and fainter. [Middle Far Right] - HST 14164+5215 is a pair of bluish lensed images symmetrically placed around a brighter, redder galaxy. [Bottom Left] - HST 16309+8230 is an edge-on disk-like galaxy (blue arc) which has been significantly distorted by the redder lensing elliptical galaxy. [Bottom Center] - HST 12368+6212 is a blue arc in the Hubble Deep Field (HDF). [Bottom Right] - HST 18078+4600 is a blue arc caused by the gravitational potential of a small group of 4 galaxies. Credit: Kavan Ratnatunga (Carnegie Mellon Univ.) and NASA

  8. Evaluation of forbidden-transition dipole moments of quasi-rigid molecules in limiting ordering schemes of vibrational-rotational interactions: numerical example for the CH4 molecule

    NASA Astrophysics Data System (ADS)

    Mikhailov, Vladimir M.

    1999-01-01

    The theory of linked groupings of vibrational-rotational interactions in molecules has been applied for the construction of the infinite series for effective dipole moments of one quantum vibrational transitions. The necessary and sufficient symmetric selection rules for forbidden transitions dipole moments have been developed. All aspects of the removal of prohibition from fully symmetric fundamentals of nonpolar molecules have been investigated. Mechanisms of activation of other inactive fundamentals of nonpolar molecules are considered also. Ab initio calculation of dipole moment function and the evaluation of the effective transition dipole moments for CH4 molecule are presented.

  9. The Top Triangle Moose

    E-print Network

    Chivukula, R S; Coleppa, B; Simmons, E H

    2010-01-01

    We introduce a deconstructed model that incorporates both Higgsless and top-color mechanisms. The model alleviates the typical tension in Higgsless models between obtaining the correct top quark mass and keeping delta-rho small. It does so by singling out the top quark mass generation as arising from a Yukawa coupling to an effective top-Higgs which develops a small vacuum expectation value, while electroweak symmetry breaking results largely from a Higgsless mechanism. As a result, the heavy partners of the SM fermions can be light enough to be seen at the LHC.

  10. The Top Triangle Moose

    NASA Astrophysics Data System (ADS)

    Chivukula, R. S.; Christensen, N. D.; Coleppa, B.; Simmons, E. H.

    2011-01-01

    We introduce a deconstructed model that incorporates both Higgsless and top-color mechanisms. The model alleviates the typical tension in Higgsless models between obtaining the correct top quark mass and keeping ?? small. It does so by singling out the top quark mass generation as arising from a Yukawa coupling to an effective top-Higgs which develops a small vacuum expectation value, while electroweak symmetry breaking results largely from a Higgsless mechanism. As a result, the heavy partners of the SM fermions can be light enough to be seen at the LHC.

  11. The Top Triangle Moose

    E-print Network

    R. S. Chivukula; N. D. Christensen; B. Coleppa; E. H. Simmons

    2010-02-11

    We introduce a deconstructed model that incorporates both Higgsless and top-color mechanisms. The model alleviates the typical tension in Higgsless models between obtaining the correct top quark mass and keeping delta-rho small. It does so by singling out the top quark mass generation as arising from a Yukawa coupling to an effective top-Higgs which develops a small vacuum expectation value, while electroweak symmetry breaking results largely from a Higgsless mechanism. As a result, the heavy partners of the SM fermions can be light enough to be seen at the LHC.

  12. Top quark measurements

    SciTech Connect

    Juste, A.; /Fermilab

    2005-11-01

    Ten years after its discovery at the Tevatron collider, we still know little about the top quark. Its large mass suggests it may play a key role in the mechanism of Electroweak Symmetry Breaking (EWSB), or open a window of sensitivity to new physics related to EWSB and preferentially coupled to it. To determine whether this is the case, precision measurements of top quark properties are necessary. The high statistics samples being collected by the Tevatron experiments during Run II start to incisively probe the top quark sector. This report summarizes the experimental status of the top quark, focusing in particular on the recent measurements from the Tevatron Run II.

  13. Top Physics at CDF

    SciTech Connect

    Moon, Chang-Seong

    2011-06-01

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

  14. Mind Molecules

    PubMed Central

    Snyder, Solomon H.

    2011-01-01

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

  15. Single molecule detection using graphene electrodes

    NASA Astrophysics Data System (ADS)

    Rangel, Norma L.; Seminario, Jorge M.

    2010-06-01

    It is shown using density functional theory that the trapping of molecules between graphene electrode plates can be used to sense molecules through their vibrational fluctuations. This hypothesis is tested using water trapped in two graphene molecules connected to a potential difference. The electric current fluctuations generated through the junction correspond to the fluctuations of the vibrational modes. Since this system yield currents in a range workable by present electronic devices, there is no need for further 'molecular amplification'. Fluctuations of the three modes of water yield similar changes of potentials in the neighbourhood accessible to other molecules; therefore, vibrations from a single water molecule, as an example, or vibrations from any other molecule can be transduced into electrical currents of magnitude compatible with present silicon technology. In the particular case of the water molecule, a rectified potential signal is obtained from the fluctuations of the antisymmetric stretching mode and a simple transduction is obtained from the symmetric stretching and bending modes. It is argued that the high sensitivity is due to the strong delocalization of the frontier molecular orbitals or molecular plasmons on graphene electrodes, which guarantees the detection based on molecular potentials or molecular vibrations; these plasmon-like molecules are of major importance for the development of molecular and nano electronics.

  16. Octupolar (C3 and S4) Symmetric Cyclized Indole Derivatives: Syntheses, Structures, and NLO Properties.

    PubMed

    Wang, Lei; Fang, Qi; Lu, Qing; Zhang, Shao-jun; Jin, Ying-ying; Liu, Zhi-qiang

    2015-09-01

    Several cyclized indole derivatives have been synthesized, and their structures been determined. The C3-symmetric single-chiral N-phenyltriindole (Tr-Ph3) crystallized in the P1 space group, and the S4-symmetric saddle-like tetraindole (TTr) crystallized in the I4? space group. The Tr-Ph3 and TTr crystals exhibit remarkable powder SHG intensities 5 and 11 times that of KH2PO4 (KDP), respectively. TTr is a useful octupolar core to build S4-symmetric molecules and crystals for second-NLO materials. PMID:26304016

  17. Top search at CDF

    SciTech Connect

    Contreras, M.; The CDF Collaboration

    1991-10-01

    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.

  18. Training Top 125

    ERIC Educational Resources Information Center

    Training, 2011

    2011-01-01

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

  19. Training Top 125

    ERIC Educational Resources Information Center

    Training, 2012

    2012-01-01

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

  20. Top physics at CDF

    SciTech Connect

    Hughes, R.E.

    1997-01-01

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

  1. The Symmetric Chiral Field Equation

    E-print Network

    Yaron Hadad

    2013-09-24

    The reduction problem of the chiral field equation on symmetric spaces is studied. It is shown that the symmetric chiral field has infinitely many local conservation laws. A recursive formula for these conservation laws is derived and the first associated integral of motion are given explicitly. Furthermore, the Zakharov-Mikhailov (inverse scattering) transform is used to derive explicit formulas for the N-soliton solution on arbitrary diagonal background. The solitons' properties and interactions are analyzed. Such solitons are naturally related to gravitational solitons of Einstein's field equations, and this result is used to clarify why the latter do not have fixed amplitude and velocities (unlike `classical' solitons). Finally, it is proven that the symmetric chiral field (matrix) equation is equivalent to a single scalar equation, which in turn, is equivalent to the Sine-Gordon equation.

  2. Symmetry-Based Techniques for Qualitative Understanding of Rovibrational Effects in Spherical-Top Molecular Spectra and Dynamics

    NASA Astrophysics Data System (ADS)

    Mitchell, Justin Chadwick

    2011-12-01

    Using light to probe the structure of matter is as natural as opening our eyes. Modern physics and chemistry have turned this art into a rich science, measuring the delicate interactions possible at the molecular level. Perhaps the most commonly used tool in computational spectroscopy is that of matrix diagonalization. While this is invaluable for calculating everything from molecular structure and energy levels to dipole moments and dynamics, the process of numerical diagonalization is an opaque one. This work applies symmetry and semi-classical techniques to elucidate numerical spectral analysis for high-symmetry molecules. Semi-classical techniques, such as the Potential Energy Surfaces, have long been used to help understand molecular vibronic and rovibronic spectra and dynamics. This investigation focuses on newer semi-classical techniques that apply Rotational Energy Surfaces (RES) to rotational energy level clustering effects in high-symmetry molecules. Such clusters exist in rigid rotor molecules as well as deformable spherical tops. This study begins by using the simplicity of rigid symmetric top molecules to clarify the classical-quantum correspondence of RES semi-classical analysis and then extends it to a more precise and complete theory of modern high-resolution spectra. RES analysis is extended to molecules having more complex and higher rank tensorial rotational and rovibrational Hamiltonians than were possible to understand before. Such molecules are shown to produce an extraordinary range of rotational level clusters, corresponding to a panoply of symmetries ranging from C4v to C2 and C1 (no symmetry) with a corresponding range of new angular momentum localization and J-tunneling effects. Using RES topography analysis and the commutation duality relations between symmetry group operators in the lab-frame to those in the body-frame, it is shown how to better describe and catalog complex splittings found in rotational level clusters. Symmetry character analysis is generalized to give analytic eigensolutions. An appendix provides vibrational analogies. For the first time, interactions between molecular vibrations (polyads) are described semi-classically by multiple RES. This is done for the nu 3/2nu4 dyad of CF4. The nine-surface RES topology of the U(9)-dyad agrees with both computational and experimental work. A connection between this and a simpler U(2) example is detailed in an Appendix.

  3. Looking for symmetric Bell inequalities

    E-print Network

    Bancal, Jean-Daniel; Pironio, Stefano

    2010-01-01

    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 238885 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.

  4. Top Quark Properties

    SciTech Connect

    Peters, Yvonne

    2011-12-01

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

  5. Top physics at CDF

    SciTech Connect

    Palencia, Enrique; /Cantabria Inst. of Phys.

    2006-06-01

    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.

  6. Strong orientational coordinates and orientational order parameters for symmetric objects

    NASA Astrophysics Data System (ADS)

    Haji-Akbari, Amir; Glotzer, Sharon C.

    2015-12-01

    Recent advancements in the synthesis of anisotropic macromolecules and nanoparticles have spurred an immense interest in theoretical and computational studies of self-assembly. The cornerstone of such studies is the role of shape in self-assembly and in inducing complex order. The problem of identifying different types of order that can emerge in such systems can, however, be challenging. Here, we revisit the problem of quantifying orientational order in systems of building blocks with non-trivial rotational symmetries. We first propose a systematic way of constructing orientational coordinates for such symmetric building blocks. We call the arising tensorial coordinates strong orientational coordinates (SOCs) as they fully and exclusively specify the orientation of a symmetric object. We then use SOCs to describe and quantify local and global orientational order, and spatiotemporal orientational correlations in systems of symmetric building blocks. The SOCs and the orientational order parameters developed in this work are not only useful in performing and analyzing computer simulations of symmetric molecules or particles, but can also be utilized for the efficient storage of rotational information in long trajectories of evolving many-body systems.

  7. Controlling Polar Molecules in Optical Lattices

    E-print Network

    S. Kotochigova; E. Tiesinga

    2006-02-01

    We investigate theoretically the interaction of polar molecules with optical lattices and microwave fields. We demonstrate the existence of frequency windows in the optical domain where the complex internal structure of the molecule does not influence the trapping potential of the lattice. In such frequency windows the Franck-Condon factors are so small that near-resonant interaction of vibrational levels of the molecule with the lattice fields have a negligible contribution to the polarizability and light-induced decoherences are kept to a minimum. In addition, we show that microwave fields can induce a tunable dipole-dipole interaction between ground-state rotationally symmetric (J=0) molecules. A combination of a carefully chosen lattice frequency and microwave-controlled interaction between molecules will enable trapping of polar molecules in a lattice and possibly realize molecular quantum logic gates. Our results are based on ab initio relativistic electronic structure calculations of the polar KRb and RbCs molecules combined with calculations of their rovibrational motion.

  8. Complex Geometry Bounded Symmetric Domains

    E-print Network

    Mok, Ngaiming

    ;· By a holomorphic metric' we mean a holo- morphic bilinear symmetric form on a com- plex manifold which conformal structure is de- fined locally by isomorphism classes of holo- morphic metrics up to complex of the holomorphic tangent bundle T = U V into the tensor product of holo- morphic vector bundles of rank 2. 4 #12

  9. Prior Distributions on Symmetric Groups

    ERIC Educational Resources Information Center

    Gupta, Jayanti; Damien, Paul

    2005-01-01

    Fully and partially ranked data arise in a variety of contexts. From a Bayesian perspective, attention has focused on distance-based models; in particular, the Mallows model and extensions thereof. In this paper, a class of prior distributions, the "Binary Tree," is developed on the symmetric group. The attractive features of the class are: it…

  10. Secure Symmetrical Multilevel Diversity Coding 

    E-print Network

    Li, Shuo

    2012-07-16

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

  11. Top quark physics: Overview

    SciTech Connect

    Parke, S.

    1998-01-01

    In this presentation I will primarily focus on top quark physics but I will include a discussion of the W-boson mass and the possibility of discovering a light Higgs boson via associated production at the Tevatron.

  12. Top quark mass measurements

    SciTech Connect

    Hill, Christopher S.; /UC, Santa Barbara

    2004-12-01

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

  13. Top physics: CDF results

    SciTech Connect

    K. Bloom

    2004-06-23

    The top quark plays an important role in the grand scheme of particle physics, and is also interesting on its own merits. We present recent results from CDF on top-quark physics based on 100-200 pb{sup -1} of p{bar p} collision data. We have measured the t{bar t} cross section in different decay modes using several different techniques, and are beginning our studies of top-quark properties. New analyses for this conference include a measurement of {sigma}{sub t{bar t}} in the lepton-plus-jets channel using a neural net to distinguish signal and background events, and measurements of top-quark branching fractions.

  14. D0 top physics

    SciTech Connect

    Pleier, M.-A.; /Rochester U.

    2005-11-01

    The Tevatron proton-antiproton collider at Fermilab operates at a center of mass energy of 1.96 TeV and is currently the only source for the production of top quarks. Recent D0 results on the top quark's production cross section and its properties such as mass, helicity of the W in its decay and branching fraction B(t {yields} Wb) are presented, and probe the validity of the Standard Model (SM).

  15. Physics of Molecules

    NASA Astrophysics Data System (ADS)

    Williams, D.; Murdin, P.

    2000-11-01

    Many varieties of molecule have been detected in the Milky Way and in other galaxies. The processes by which these molecules are formed and destroyed are now broadly understood (see INTERSTELLAR CHEMISTRY). These molecules are important components of galaxies in two ways. Firstly, radiation emitted by molecules enables us to trace the presence of diffuse gas, to infer its physical properties and ...

  16. Axi-symmetric models of ultraviolet radiative transfer with applications to circumstellar disk chemistry

    E-print Network

    Zadelhoff, Gerd-Jan van

    Axi-symmetric models of ultraviolet radiative transfer with applications to circumstellar disk to calculate molecular lines profiles. The chemistry is driven by ultraviolet radiation and freeze-out of molecules CONCLUSIONS Radicals like CN and C¦ H need 2D UV radiative transfer for a correct abundance

  17. Top quark physics: Future measurements

    SciTech Connect

    Frey, R.; Vejcik, S.; Berger, E.L.

    1997-04-04

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

  18. Symmetric Tensor Decomposition Description of Fermionic Many-Body Wavefunctions

    E-print Network

    Uemura, Wataru

    2012-01-01

    The configuration interaction (CI) is a versatile wavefunction theory for interacting fermions but it involves an extremely long CI series. Using a symmetric tensor decomposition (STD) method, we convert the CI series into a compact and numerically tractable form. The converted series encompasses the Hartree-Fock state in the first term and rapidly converges to the full-CI state, as numerically tested using small molecules. Provided that the length of the STD-CI series grows only moderately with the increasing complexity of the system, the new method will serve as one of the alternative variational methods to achieve full-CI with enhanced practicability.

  19. Distinguishability of the symmetric states

    E-print Network

    M. A. Jafarizadeh; P. Sadeghi; d. Akhgar; P. Mahmoudi

    2015-03-20

    In this paper, the distinguishability of multipartite geometrically uniform quantum states obtained from a single reference state is studied in the symmetric subspace. We specially focus our attention on the unitary transformation in a way that the produced states remain in the symmetric subspace, so rotation group with Jy as the generator of rotation is applied. The optimal probability and measurements are obtained for the pure and some special mixed separable states and the results are compared with those obtained at the previous articles for the special cases. The results are valid for lin- early dependent states. The discrimination of these states is also investigated using the separable measurement. We introduce appropriate transformation to gain the optimal separable measurements equivalent to the optimal global measurements with the same optimal probability.

  20. Top quark production at CDF

    SciTech Connect

    Moed, Shulamit; /Harvard U.

    2010-01-01

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

  1. Viscosity in spherically symmetric accretion

    E-print Network

    Arnab K. Ray

    2004-09-27

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

  2. Top-ophilia

    SciTech Connect

    Quigg, Chris; /Fermilab

    2008-01-01

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

  3. Kernel mucking in top

    SciTech Connect

    LeFebvre, W.

    1994-08-01

    For many years, the popular program top has aided system administrations in examination of process resource usage on their machines. Yet few are familiar with the techniques involved in obtaining this information. Most of what is displayed by top is available only in the dark recesses of kernel memory. Extracting this information requires familiarity not only with how bytes are read from the kernel, but also what data needs to be read. The wide variety of systems and variants of the Unix operating system in today`s marketplace makes writing such a program very challenging. This paper explores the tremendous diversity in kernel information across the many platforms and the solutions employed by top to achieve and maintain ease of portability in the presence of such divergent systems.

  4. Top quark physics at CDF

    SciTech Connect

    J. Nielsen

    2004-06-01

    The existence of the top quark, discovered by CDF and D0 in 1995, has been re-established in the burgeoning dataset being collected in Run 2 of the Tevatron at Fermilab. Results from CDF on the top quark production cross section and top quark mass are consistent with the Standard Model expectations. The well-characterized top data samples will make it possible in the future to probe further for new physics in the top quark sector.

  5. Ten Top Tech Trends

    ERIC Educational Resources Information Center

    McLester, Susan

    2008-01-01

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

  6. Top quark physics at CDF

    SciTech Connect

    Nielsen, Jason

    2004-04-30

    The existence of the top quark, discovered by CDF and D0 in 1995, has been re-established in the burgeoning dataset being collected in Run 2 of the Tevatron at Fermilab. Results from CDF on the top quark production cross section and top quark mass are consistent with the Standard Model expectations. The well-characterized top data samples will make it possible in the future to probe further for new physics in the top quark sector. This report summarizes recent CDF top quark physics results.

  7. Spherically symmetric canonical quantum gravity

    NASA Astrophysics Data System (ADS)

    Brahma, Suddhasattwa

    2015-06-01

    Canonical quantization of spherically symmetric space-times is carried out, using real-valued densitized triads and extrinsic curvature components, with specific factor-ordering choices ensuring in an anomaly free quantum constraint algebra. Comparison with previous work [Nucl. Phys. B399, 211 (1993)] reveals that the resulting physical Hilbert space has the same form, although the basic canonical variables are different in the two approaches. As an extension, holonomy modifications from loop quantum gravity are shown to deform the Dirac space-time algebra, while going beyond "effective" calculations.

  8. Dibaryons as axially symmetric skyrmions

    E-print Network

    Thomas, G L; Wirzba, A

    1994-01-01

    Dibaryons configurations are studied in the framework of the bound state soliton model. A generalized axially symmetric ansatz is used to determine the soliton background. We show that once the constraints imposed by the symmetries of the lowest energy torus configuration are satisfied all spurious states are removed from the dibaryon spectrum. In particular, we show that the lowest allowed state in the $S=-2$ channel carries the quantum numbers of the H particle. We find that, within our approximations, this particle is slightly bound in the model. We discuss, however, that vacuum effects neglected in the present calculation are very likely to unbind the H.

  9. Demystified ... adhesion molecules.

    PubMed Central

    Freemont, A J

    1998-01-01

    The cell adhesion molecules are ubiquitous recognition molecules that allow cells to communicate with one another and their environment. Through these molecules, complex alterations in the cytoplasmic messenger pathways and the microfilamentous cytoskeleton can lead to profound alterations in cell division, differentiation, behaviour, and function (fig 9). It is difficult to conceive of a group of molecules that could be more important to pathologists and to their understanding of disease processes. PMID:9893742

  10. Top of the hill.

    PubMed

    Lubell, Jennifer

    2009-08-24

    With healthcare reform the hottest topic in Washington (and at congressional town halls) this summer, it's no surprise President Barack Obama tops our 100 Most Powerful People in Healthcare ranking, joined by plenty of other power players on the Hill. "Clearly, the president is pushing hard on his goals to expand access to care, to reform health insurance and to control costs," says LifePoint's Bill Carpenter. PMID:19731430

  11. Probabilistic cloning of three symmetric states

    SciTech Connect

    Jimenez, O.; Bergou, J.; Delgado, A.

    2010-12-15

    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.

  12. The Similarity Relations Set on the Basis of Symmetrization of the Liquid-Vapor Phase Diagram.

    PubMed

    Apfelbaum, E M; Vorob'ev, V S

    2015-07-01

    An approach to symmetrize the liquid-vapor phase coexistence curve is proposed. It is based on the introduction of the lattice-like density x = ?1/(?1 + ?2), where ?1 and ?2 are the densities along the liquid-gas binodal. The global symmetrical phase diagram is created using experimental and simulation data for the real substances and models (noble gases, polyatomic molecules, organic substances and two metals, van der Waals system, Lennard-Jones system). The pressure and the temperature along the binodal are shown to satisfy some new similarity relations. PMID:26039358

  13. Hypercubane: DFT-based prediction of an Oh-symmetric double-shell hydrocarbon

    NASA Astrophysics Data System (ADS)

    Pichierri, Fabio

    2014-09-01

    Using density functional theory we design a molecular analog of the four-dimensional hypercube or tesseract which we called hypercubane. The title hydrocarbon (C40H24) is Oh-symmetric like cubane and is characterized by a double-shell architecture. The perfluorinated analog of hypercubane also is stable with a positive value of the electron affinity. Removal of the C8 core from hypercubane yields a hollowed Oh-symmetric hydrocarbon with enough room to host a single atom/ion guest. The resonances of the NMR-active 13C and 1H nuclei have been computed so as to assist the spectroscopic identification of the predicted molecules.

  14. Top Physics at the LHC

    E-print Network

    P. de Jong

    2009-02-27

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

  15. Top physics results at CDF

    SciTech Connect

    Vickey, Trevor; /Illinois U., Urbana

    2005-05-01

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

  16. Top quark physics: Future Measurements

    SciTech Connect

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

    1996-12-31

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

  17. Modern Symmetric Cryptography methodologies and its applications

    E-print Network

    Malayeri, Amin Daneshmand

    2009-01-01

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

  18. Linearization of Moffat's Symmetric Complex Metric Gravity

    E-print Network

    Joakim Munkhammar

    2009-09-19

    In this paper we investigate a complex symmetric generalization of general relativity and in particular we investigate its linearized field equations. We begin by reviewing some basic definitions and structures in Moffat's symmetric complex metric field theory of gravity. We then move on to derive the linearized retarded complex field equations. In addition to this we also derive a linearization of Moffat's field equations based on the more rigorous Fermi coordinate approach. In conclusion it is shown that the linearized symmetric complex field equations leads to a complex form of gravitomagnetism. We also briefly review the gravitational wave equation from the source less linearized symmetric complex field equations and discuss some open problems.

  19. Nonlinear {PT}-symmetric plaquettes

    NASA Astrophysics Data System (ADS)

    Li, Kai; Kevrekidis, P. G.; Malomed, Boris A.; Günther, Uwe

    2012-11-01

    We introduce four basic two-dimensional (2D) plaquette configurations with onsite cubic nonlinearities, which may be used as building blocks for 2D {PT}-symmetric lattices. For each configuration, we develop a dynamical model and examine its {P} {T}symmetry. The corresponding nonlinear modes are analyzed starting from the Hamiltonian limit, with zero value of the gain-loss coefficient, ?. Once the relevant waveforms have been identified (chiefly, in an analytical form), their stability is examined by means of linearization in the vicinity of stationary points. This reveals diverse and, occasionally, fairly complex bifurcations. The evolution of unstable modes is explored by means of direct simulations. In particular, stable localized modes are found in these systems, although the majority of identified solutions are unstable. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’.

  20. A Minimally Symmetric Higgs Boson

    E-print Network

    Ian Low

    2015-06-10

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

  1. A maximally symmetric no-scale inflationary universe

    NASA Astrophysics Data System (ADS)

    Kounnas, C.; Quiros, M.

    1985-02-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  3. Exploring Rotation-Vibration Coupling in Highly Fluxional Molecules Using Surface Hopping Diffusion Monte Carlo

    NASA Astrophysics Data System (ADS)

    Petit, Andrew S.; McCoy, Anne B.

    2012-06-01

    Diffusion Monte Carlo (DMC) has widely been shown to be a powerful technique for studying ro-vibrational states of highly fluxional molecules and clusters. An extension of DMC to multiple potential energy surfaces (PESs) based on the Tully surface hopping approach has previously been developed by our group. Here, we report an application of this approach to the calculation of rotationally excited states of systems with pronounced rotation-vibration coupling and large-amplitude, zero-point vibrational motion. More specifically, for a chosen value of J, each walker in the DMC ensemble is expanded in a symmetric top basis. The expansion coefficients are updated each time-step based on the action of the rigid-rotor asymmetric top Hamiltonian. This Hamiltonian is constructed using the inverse moment of inertia tensor evaluated in the Eckart frame at the walker's position in configuration space. Each walker is then localized onto a single, K-dependent effective PES, and the effective potential energy associated with the walker's position on that surface determines the evolution of its weight in the DMC ensemble. Preliminary results of the application of this methodology to model systems such as H_3^+ and H_2D^+ will be discussed as well as its prospect for accurately evaluating ro-vibrational states of systems like CH_5^+. Finally, a comparison of this technique with our previously developed fixed-node DMC approach for the evaluation of ro-vibrational energies and wave functions will be presented. J. C. Tully, J. Chem. Phys. 93, 1061 (1990). A.B. McCoy, Chem. Phys. Lett. 321, 71 (2000). A. S. Petit, B. A. Wellen, and A. B. McCoy, J. Chem. Phys. 136, 074101 (2012).

  4. Cylindrically symmetric electrohydrodynamic patterning Paru Deshpande,1,

    E-print Network

    Cylindrically symmetric electrohydrodynamic patterning Paru Deshpande,1, * Leonard F. Pease III,2; published 21 October 2004) Cylindrically symmetric structures such as concentric rings and rosettes arise rings and theory capable of explaining these and other cylindrical structures are presented. These rings

  5. Continuity and Separation in Symmetric Topologies

    ERIC Educational Resources Information Center

    Harris, J.; Lynch, M.

    2007-01-01

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

  6. Generalized geometry and non-symmetric gravity

    E-print Network

    Jurco, Branislav; Schupp, Peter; Vysoky, Jan

    2015-01-01

    Generalized geometry provides the framework for a systematic approach to non-symmetric metric gravity theory and naturally leads to an Einstein-Kalb-Ramond gravity theory with totally anti-symmetric contortion. The approach is related to the study of the low-energy effective closed string gravity actions.

  7. Trapped Particles in $PT$ Symmetric Theories

    E-print Network

    C. Yuce; A. Kurt; A. Kucukaslan

    2006-02-13

    $PT$ symmetric quantum mechanics for a particle trapped by the generalized non-Hermitian harmonic oscillator potential is studied. It is shown that energy and the expectation value of the position operator $x$ can not be real simultaneously, if the particle is trapped. Non-vanishing boundary conditions for the trapped particle in $PT$ symmetric theory are also discussed.

  8. Top-Higgs and Top-pion phenomenology in the Top Triangle Moose model

    E-print Network

    Chivukula, R Sekhar; Logan, Heather E; Martin, Adam; Simmons, Elizabeth H

    2011-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Chivukula, R. Sekhar; Simmons, Elizabeth H.; Coleppa, Baradhwaj; Logan, Heather E.; Martin, Adam

    2011-03-01

    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.

  10. Top-Higgs and Top-pion phenomenology in the Top Triangle Moose model

    E-print Network

    R. Sekhar Chivukula; Baradhwaj Coleppa; Heather E. Logan; Adam Martin; Elizabeth H. Simmons

    2011-01-31

    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.

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

    SciTech Connect

    Chivukula, R. Sekhar; Simmons, Elizabeth H.; Coleppa, Baradhwaj; Logan, Heather E.; Martin, Adam

    2011-03-01

    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.

  12. Trapping polar molecules in an ac trap

    SciTech Connect

    Bethlem, Hendrick L.; Veldhoven, Jacqueline van; Schnell, Melanie; Meijer, Gerard

    2006-12-15

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

  13. TopView - ATLAS top physics analysis package

    E-print Network

    Shibata, A

    2007-01-01

    TopView is a common analysis package which is widely used in the ATLAS top physics working group. The package is fully based on the official ATLAS software Athena and EventView and playing a central role in the collaborative analysis model. It is a functional package which accounts for a broad range issues in implementing physics analysis. As well as being a modular framework suitable as a common workplace for collaborators, TopView implements numerous analysis tools including a complete top-antitop reconstruction and single top reconstruction. The package is currently used to produce common ntuple from Monte Carlo production and future use cases are under rapid development. In this paper, the design and ideas behind TopView and the performance of the analyses implemented in the package are presented with detailed documentation of the contents and instruction for using the package.

  14. Top quark mass measurements

    SciTech Connect

    L. Cerrito

    2004-07-16

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

  15. Trapping molecules on chips

    E-print Network

    Santambrogio, Gabriele

    2015-01-01

    In the last years, it was demonstrated that neutral molecules can be loaded on a microchip directly from a supersonic beam. The molecules are confined in microscopic traps that can be moved smoothly over the surface of the chip. Once the molecules are trapped, they can be decelerated to a standstill, for instance, or pumped into selected quantum states by laser light or microwaves. Molecules are detected on the chip by time-resolved spatial imaging, which allows for the study of the distribution in the phase space of the molecular ensemble.

  16. The importance of new molecules in selective perfumery.

    PubMed

    Roucel, Maurice; Grau, Fanny

    2014-10-01

    Perfumery can only evolve thanks to new ingredients. We highlight herein some key molecules and their use in 'Selective Perfumery': the violet odorant undecavertol, the floral nerolione and coumarone, the gourmand cappuccino levistamel, the sandalwood notes Sandranol(®) or Bacdanol(®) , the fruity top note Magnolia Flower oil, and finally the woody ambery Ambrocenide(®) . PMID:25329780

  17. Controlling electric, magnetic, and chiral dipolar emission with PT-symmetric potentials

    NASA Astrophysics Data System (ADS)

    Alaeian, Hadiseh; Dionne, Jennifer A.

    2015-06-01

    We investigate the effect of parity-time (PT) symmetric optical potentials on the radiation of achiral and chiral dipole sources. Two properties unique to PT-symmetric potentials are observed. First, the dipole can be tuned to behave as a strong optical emitter or absorber based on the non-Hermiticity parameter and the dipole location. Second, exceptional points give rise to new system resonances that lead to orders-of-magnitude enhancements in the dipolar emitted or absorbed power. Utilizing these properties, we show that enantiomers of chiral molecules near PT-symmetric metamaterials exhibit a 4.5-fold difference in their emitted power and decay rate. The results of this work could enable new atom-cavity interactions for quantum optics, as well as all-optical enantioselective separation.

  18. Venturing Beyond Known Physics with Top Quarks

    E-print Network

    ?umer, Slobodan

    Venturing Beyond Known Physics with Top Quarks Jernej F. Kamenik 19/07/2011, Ljubljana #12;Standard these issues by studying the top quark? #12;Top quark within the Standard Model Is the top quark special? #12;Top quark within the Standard Model Scientific American Is the top quark special? Heaviest known

  19. The influence of symmetric internal loops on the flexibility of RNA.

    PubMed

    Zacharias, M; Hagerman, P J

    1996-03-29

    Internal loops are structural elements, often highly conserved, that are found in many RNA molecules of biological importance. They consist of short stretches of sequence in which the bases in one strand are not able to form canonical pairs with bases in the other strand, and are bounded on either side by helical RNA. In an effort to examine the influence of internal loops on the relative angular orientations of the flanking helices, we have quantified the apparent bend angles for symmetric internal loops of the form A(n)-A(n) and U(n)-U(n) (n=2, 4, and 6), located at the center of 150 to 154 bp RNA molecules, using the method of transient electric birefringence. This hydrodynamic method exploits the extreme sensitivity of the rate of rotational reorientation of the RNA molecules to the presence and magnitude of internal bends and/or points of increased flexibility. The birefringence decay behavior of the loop-containing RNA molecules was found to be much less strongly influenced by the presence of symmetric internal loops than by bulges of the same sequence and size. This general observation is mirrored by the electrophoretic behavior of the loop-containing molecules, which are much less strongly retarded on polyacrylamide gels than are corresponding, bulge-containing RNA molecules. The apparent bend angles for the symmetric loops range from approximately 20 degrees to 40 degrees as n is increased 2 to 6 with a marginal shift to smaller angles in the presence of Mg2+. The apparent angles were similar when represented either as fixed bends of the specified angles (static representation), or as points of increased flexibility of specified root-mean-square angle (dynamic representation). For the. For the latter representation, the corresponding angular dispersion would correspond to a loop persistence length of approximately 60 to 150 A, compared to 700 A for duplex RNA and depending slightly on sequence and buffer conditions. PMID:8609623

  20. Top physics results from CDF

    SciTech Connect

    Gomez, Gervasio; /Cantabria Inst. of Phys.

    2005-05-01

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

  1. Quantum Behavior of Water Molecules Confined to Nanocavities in Gemstones.

    PubMed

    Gorshunov, Boris P; Zhukova, Elena S; Torgashev, Victor I; Lebedev, Vladimir V; Shakurov, Gil'man S; Kremer, Reinhard K; Pestrjakov, Efim V; Thomas, Victor G; Fursenko, Dimitry A; Dressel, Martin

    2013-06-20

    When water is confined to nanocavities, its quantum mechanical behavior can be revealed by terahertz spectroscopy. We place H2O molecules in the nanopores of a beryl crystal lattice and observe a rich and highly anisotropic set of absorption lines in the terahertz spectral range. Two bands can be identified, which originate from translational and librational motions of the water molecule isolated within the cage; they correspond to the analogous broad bands in liquid water and ice. In the present case of well-defined and highly symmetric nanocavities, the observed fine structure can be explained by macroscopic tunneling of the H2O molecules within a six-fold potential caused by the interaction of the molecule with the cavity walls. PMID:26283245

  2. Spherically symmetric charged compact stars

    NASA Astrophysics Data System (ADS)

    Maurya, S. K.; Gupta, Y. K.; Ray, Saibal; Chowdhury, Sourav Roy

    2015-08-01

    In this article we consider the static spherically symmetric metric of embedding class 1. When solving the Einstein-Maxwell field equations we take into account the presence of ordinary baryonic matter together with the electric charge. Specific new charged stellar models are obtained where the solutions are entirely dependent on the electromagnetic field, such that the physical parameters, like density, pressure etc. do vanish for the vanishing charge. We systematically analyze altogether the three sets of Solutions I, II, and III of the stellar models for a suitable functional relation of . However, it is observed that only the Solution I provides a physically valid and well-behaved situation, whereas the Solutions II and III are not well behaved and hence not included in the study. Thereafter it is exclusively shown that the Solution I can pass through several standard physical tests performed by us. To validate the solution set presented here a comparison has also been made with that of the compact stars, like , , , , and , and we have shown the feasibility of the models.

  3. PT-symmetric laser absorber

    SciTech Connect

    Longhi, Stefano

    2010-09-15

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

  4. Baryon symmetric big bang cosmology

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1978-01-01

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

  5. 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...

  6. Molecules between the Stars.

    ERIC Educational Resources Information Center

    Verschuur, Gerrit L.

    1987-01-01

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

  7. Enzymatic DNA molecules

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  8. Single Top production at LHC

    E-print Network

    M. Mohammadi Najafabadi

    2006-05-15

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

  9. Top-Working Pecan Trees. 

    E-print Network

    Kyle, E. J.

    1916-01-01

    and Mechanical College of Texas (In cooperation with the United States Department of Agriculture.) ,I' APRIL, 1916 EXTENSION SERVICE No. B-21 TOP-WORKING PECAN TREES Address CLARENCE OUSLEY Director of Extension Service, College Station, Texas TOP WORKING PECAN... TREES By E. J. Kyle, Professor of Horticulture, Dean of the School of Agriculture, Agricultural and Mechanical College of Texas. Top-working pecan trees has passed beyond the experimental stage. Some of the methods employed during the experimental period...

  10. Resonances and instabilities in symmetric multistep methods

    E-print Network

    Gerald D. Quinlan

    1999-01-12

    The symmetric multistep methods developed by Quinlan and Tremaine (1990) are shown to suffer from resonances and instabilities at special stepsizes when used to integrate nonlinear equations. This property of symmetric multistep methods was missed in previous studies that considered only the linear stability of the methods. The resonances and instabilities are worse for high-order methods than for low-order methods, and the number of bad stepsizes increases with the number frequencies present in the solution. Symmetric methods are still recommended for some problems, including long-term integrations of planetary orbits, but the high-order methods must be used with caution.

  11. Vibrational Spectroscopy of Molecules Chemically Bound to Electrodes

    NASA Astrophysics Data System (ADS)

    Demir, Firuz

    The atomic scale structures of the molecule-metal interfaces of single-molecule nanowires forming stable electrically conducting bridges between metal electrodes have been studied intensively for more than a decade but have remained elusive, and are still central to the field of single-molecule nanoelectronics. In this theoretical study, I show how inelastic tunneling spectroscopy experiments with the help of theory are now capable of determining the unknown bonding geometries between the molecule and electrodes, and thus resolving the long standing "contact problem" of molecular nanoelectronics. As an example I consider the propanedithiolate (PDT) molecules bridging gold nanocontacts in the recent experiment of Hihath et al. [Nano Lett. 8, 1673 (2008)] 1. Based on ab initio density functional and semi-empirical calculations, I find the relaxed geometries and vibrational modes of extended molecules each consisting of one or two PDT molecules connecting two gold nanoclusters and calculate their elastic conductances and inelastic tunneling spectra. Comparing my results with the data of Hihath et al., I find that the most frequently realized conformation in the experiment was trans molecules top-site bonded to both electrodes. I identify the features observed in the experimental inelastic electron tunneling spectroscopy (IETS) of these molecules at phonon energies near 46, 40 and 42 meV and show the switching from the 42 meV vibrational mode to the 46 meV mode observed in the experiment to be due to the transition of trans molecules from top-bridge to top-site bonding geometries. I extend my study to evaluating the effect of thiol hydrogen atoms in molecular junctions and show how IETS can be used to monitor gold-thiol bond formation and the cleavage of the S-H bond during this process. For pairs of PDT molecules connecting the gold electrodes in parallel, I find total elastic conductances close to twice those of single molecules bridging the contacts with similar bonding conformations and small splittings of the vibrational mode energies for the modes that are the most sensitive to the molecule-electrode bonding geometries. I also describe the dependence of the transport properties of alkanedithiols molecular junctions on the length of the alkane chain.

  12. Pinning down top dipole moments with ultraboosted tops

    NASA Astrophysics Data System (ADS)

    Aguilar-Saavedra, Juan A.; Fuks, Benjamin; Mangano, Michelangelo L.

    2015-05-01

    We investigate existing and future hadron-collider constraints on the top dipole chromomagnetic and chromoelectric moments, two quantities that are expected to be modified in the presence of new physics. We focus first on recent measurements of the inclusive top pair production cross section at the Tevatron and at the Large Hadron Collider. We then analyze the role of top-antitop events produced at very large invariant masses, in the context of the forthcoming 13-14 TeV runs of the LHC, and at a future 100 TeV proton-proton collider. In this latter case, the selection of semileptonic decays to hard muons allows to tag top quarks boosted to the multi-TeV regime, strongly reducing the QCD backgrounds and leading to a significant improvement in the sensitivity to anomalous top couplings.

  13. CD molecules 2005: human cell differentiation molecules.

    PubMed

    Zola, Heddy; Swart, Bernadette; Nicholson, Ian; Aasted, Bent; Bensussan, Armand; Boumsell, Laurence; Buckley, Chris; Clark, Georgina; Drbal, Karel; Engel, Pablo; Hart, Derek; Horejsí, Václav; Isacke, Clare; Macardle, Peter; Malavasi, Fabio; Mason, David; Olive, Daniel; Saalmueller, Armin; Schlossman, Stuart F; Schwartz-Albiez, Reinhard; Simmons, Paul; Tedder, Thomas F; Uguccioni, Mariagrazia; Warren, Hilary

    2005-11-01

    The immune system works through leukocytes interacting with each other, with other cells, with tissue matrices, with infectious agents, and with other antigens. These interactions are mediated by cell-surface glycoproteins and glycolipids. Antibodies against these leukocyte molecules have provided powerful tools for analysis of their structure, function, and distribution. Antibodies have been used widely in hematology, immunology, and pathology, and in research, diagnosis, and therapy. The associated CD nomenclature is commonly used when referring to leukocyte surface molecules and antibodies against them. It provides an essential classification for diagnostic and therapeutic purposes. The most recent (8th) Workshop and Conference on Human Leukocyte Differentiation Antigens (HLDA), held in Adelaide, Australia, in December 2004, allocated 95 new CD designations and made radical changes to its aims and future operational strategy in order to maintain its relevance to modern human biology and clinical practice. PMID:16020511

  14. PARTITION COMPLEXES, TITS BUILDINGS AND SYMMETRIC PRODUCTS

    E-print Network

    PARTITION COMPLEXES, TITS BUILDINGS AND SYMMETRIC PRODUCTS- tition complex, and identify it as the Tits building. This gives a homological relationship of equivalence relations on a finite set; a Tits building is a geometric object associated to the poset

  15. Time-Symmetric Quantum Theory of Smoothing

    E-print Network

    Tsang, Mankei

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

  16. Multiple Symmetric Lipomatosis: A Diagnostic Dilemma

    PubMed Central

    Mimica, Mladen; Pravdic, Danijel; Nakas-Icindic, Emina; Karin, Maja; Babic, Emil; Tomic, Monika; Bevanda, Milenko

    2013-01-01

    Introduction. Multiple symmetric lipomatosis, or Madelung's disease, is a rare condition which is characterized with large symmetrical accumulation of noncapsulated fat tissue in upper arms, neck, and shoulder areas. The disease etiology is unknown, with the highest incidence in the Mediterranean region. Case Presentation. Here, we present the case of Madelung's disease with symmetric fat distribution throughout the neck and history of alcoholism. The patient was treated from several diseases associated with alcoholism and hospitalized several times, but the diagnosis of Madelung's disease was omitted. The thyroid gland disease was excluded, while enlargement of the neck adipose tissue was attributed to obesity. Conclusions. This study points out possible diagnostic mistakes when a physician is not aware of a differentiation diagnosis of symmetrically enlarged neck masses, especially in geographic regions with high incidence of this disease. PMID:23983713

  17. Martingale Rosenthal inequalities in symmetric spaces

    SciTech Connect

    Astashkin, S V

    2014-12-31

    We establish inequalities similar to the classical Rosenthal inequalities for sequences of martingale differences in general symmetric spaces; a central role is played here by the predictable quadratic characteristic of a martingale. Bibliography: 26 titles.

  18. Observation of ultralong-range Rydberg molecules.

    PubMed

    Bendkowsky, Vera; Butscher, Björn; Nipper, Johannes; Shaffer, James P; Löw, Robert; Pfau, Tilman

    2009-04-23

    Rydberg atoms have an electron in a state with a very high principal quantum number, and as a result can exhibit unusually long-range interactions. One example is the bonding of two such atoms by multipole forces to form Rydberg-Rydberg molecules with very large internuclear distances. Notably, bonding interactions can also arise from the low-energy scattering of a Rydberg electron with negative scattering length from a ground-state atom. In this case, the scattering-induced attractive interaction binds the ground-state atom to the Rydberg atom at a well-localized position within the Rydberg electron wavefunction and thereby yields giant molecules that can have internuclear separations of several thousand Bohr radii. Here we report the spectroscopic characterization of such exotic molecular states formed by rubidium Rydberg atoms that are in the spherically symmetric s state and have principal quantum numbers, n, between 34 and 40. We find that the spectra of the vibrational ground state and of the first excited state of the Rydberg molecule, the rubidium dimer Rb(5s)-Rb(ns), agree well with simple model predictions. The data allow us to extract the s-wave scattering length for scattering between the Rydberg electron and the ground-state atom, Rb(5s), in the low-energy regime (kinetic energy, <100 meV), and to determine the lifetimes and the polarizabilities of the Rydberg molecules. Given our successful characterization of s-wave bound Rydberg states, we anticipate that p-wave bound states, trimer states and bound states involving a Rydberg electron with large angular momentum-so-called trilobite molecules-will also be realized and directly probed in the near future. PMID:19396141

  19. Learning at the Top. Symposium.

    ERIC Educational Resources Information Center

    2002

    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 as…

  20. Top results from the Tevatron

    SciTech Connect

    E. Barberis

    2002-01-18

    This paper summarizes the latest measurements of the properties of the top quark as determined by the CDF and D0 collaborations during the first run of the Fermilab Tevatron p{bar p} collider (1992-1996). Prospects for future measurements of the top quark at the upgraded Tevatron collider are also presented.

  1. Image registration under symmetric conditions: novel approach

    NASA Astrophysics Data System (ADS)

    Duraisamy, Prakash; Yousef, Amr; Buckles, Bill; Jackson, Steve

    2015-03-01

    Registering the 2D images is one of the important pre-processing steps in many computer vision applications like 3D reconstruction, building panoramic images. Contemporary registration algorithm like SIFT (Scale Invariant Feature transform) was not quite success in registering the images under symmetric conditions and under poor illuminations using DoF (Difference of Gaussian) features. In this paper, we introduced a novel approach for registering the images under symmetric conditions.

  2. Symmetric states: Their nonlocality and entanglement

    SciTech Connect

    Wang, Zizhu; Markham, Damian

    2014-12-04

    The nonlocality of permutation symmetric states of qubits is shown via an extension of the Hardy paradox and the extension of the associated inequality. This is achieved by using the Majorana representation, which is also a powerful tool in the study of entanglement properties of symmetric states. Through the Majorana representation, different nonlocal properties can be linked to different entanglement properties of a state, which is useful in determining the usefulness of different states in different quantum information processing tasks.

  3. Is the quark- mixing matrix moduli symmetric?

    E-print Network

    S. Chaturvedi; Virendra Gupta

    2003-11-15

    If the unitary quark- mixing matrix, $V$, is moduli symmetric then it depends on three real parameters. This means that there is a relation between the four parameters needed to parametrize a general $V$. It is shown that there exists a very simple relation involving $|V_{11}|^2, |V_{33}|^2,\\orh $ and $\\oet$. This relation is compared with the present experimental data. It is concluded that a moduli symmetric $V$ is not ruled out.

  4. Top of Olympus Mons

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-455, 17 August 2003

    Olympus Mons is considered to be the largest and tallest volcano in the Solar System. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows the western summit region of Olympus Mons. This area is at an elevation just over 20 km (12 mi) above the 0 km martian datum. The bright feature on the right (east) side of the image is the uppermost wall of the caldera (collapse pit) at the top of the volcano. This image shows a lava flow that was cut by the pit walls when the caldera collapse occurred. Below (south of) the lava flow is a narrow channel formed by lava at some time in the distant past. This view of the summit region of Olympus Mons is located near 10.6oN, 134.0oW. The area shown is about 7.9 km (4.9 mi) across. Sunlight illuminates the scene from the right.

  5. Dark matter on top

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  6. Probing single molecule dynamics

    SciTech Connect

    Xie, X.S.; Dunn, R.C. )

    1994-07-15

    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.

  7. Single-Molecule Enzymology

    SciTech Connect

    Xie, Xiaoliang; Lu, H PETER.

    1999-06-04

    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.

  8. Of Molecules and Models.

    ERIC Educational Resources Information Center

    Brinner, Bonnie

    1992-01-01

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

  9. Training Top 10 Hall of Fame

    ERIC Educational Resources Information Center

    Training, 2012

    2012-01-01

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

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

    SciTech Connect

    Boisvert, V.; /Rochester U.

    2006-08-01

    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.

  11. Symmetric generation of Coxeter groups Ben Fairbairn and Jurgen Muller

    E-print Network

    Mueller, Jürgen

    Symmetric generation of Coxeter groups Ben Fairbairn and J¨urgen M¨uller Abstract. We provide involutory symmetric generating sets of finitely gener- ated Coxeter groups, fulfilling a suitable finiteness. Mathematics Subject Classification (2000). 20F55, 20F05. Keywords. symmetric generation, symmetric

  12. Symmetric generation of Coxeter groups Ben Fairbairn and Jurgen Muller

    E-print Network

    Mueller, Jürgen

    Symmetric generation of Coxeter groups Ben Fairbairn and JË?urgen MË?uller Abstract. We provide involutory symmetric generating sets of finitely gener­ ated Coxeter groups, fulfilling a suitable finiteness Subject Classification (2000). 20F55, 20F05. Keywords. symmetric generation, symmetric presentation

  13. Turbulence near thunderstorm tops

    NASA Technical Reports Server (NTRS)

    Lester, Peter F.

    1993-01-01

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

  14. Symmetric Galerkin boundary formulations employing curved elements

    NASA Technical Reports Server (NTRS)

    Kane, J. H.; Balakrishna, C.

    1993-01-01

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

  15. SW New Mexico Oil Well Formation Tops

    SciTech Connect

    Shari Kelley

    2015-10-21

    Rock formation top picks from oil wells from southwestern New Mexico from scout cards and other sources. There are differing formation tops interpretations for some wells, so for those wells duplicate formation top data are presented in this file.

  16. Single top quark from technipion production

    E-print Network

    Baringer, Philip S.

    1997-09-01

    We investigate the contribution of technicolor mechanisms to the production of single top quarks at hadron colliders. Technipions with a mass larger than the top quark mass will decay predominantly to a top quark plus a bottom antiquark. We...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  18. Accommodation of a highly symmetric core within a symmetric protein superfold

    E-print Network

    Blaber, Michael

    Accommodation of a highly symmetric core within a symmetric protein superfold STEPHEN R. BRYCH An alternative core packing group, involving a set of five positions, has been introduced into human acidic FGF-1. This alternative group was designed so as to constrain the primary structure within the core region to the same

  19. Trajectory correction propulsion for TOPS

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

  20. Progress in Top Quark Physics

    SciTech Connect

    Thomson, Evelyn J.

    2006-07-11

    Experimental measurements of the properties of the top quark have improved and will continue to improve significantly, with the excellent operation of the CDF and D0 experiments and the Tevatron pp-bar collider at the Fermi National Accelerator Laboratory. All of the final state experimental signatures from top quark production and decay are being analysed to test if this most massive quark is sensitive to new physics beyond the standard model. So far, observations are consistent with the standard model. New techniques have dramatically improved the precision of the top quark mass measurement to 1.7% and set the stage for a sub-1% measurement by 2008. This improved knowledge of the top quark mass sharpens the standard model prediction for the mass of the undiscovered Higgs boson, with implications for Higgs studies at the future LHC and ILC.

  1. Progress in top quark physics

    SciTech Connect

    Thomson, Evelyn J.; /Pennsylvania U.

    2006-02-01

    Experimental measurements of the properties of the top quark have improved and will continue to improve significantly, with the excellent operation of the CDF and D0 experiments and the Tevatron p{bar p} collider at the Fermi National Accelerator Laboratory. All of the final state experimental signatures from top quark production and decay are being analyzed to test if this most massive quark is sensitive to new physics beyond the standard model. So far, observations are consistent with the standard model. New techniques have dramatically improved the precision of the top quark mass measurement to 1.7% and set the stage for a sub-1% measurement by 2008. This improved knowledge of the top quark mass sharpens the standard model prediction for the mass of the undiscovered Higgs boson, with implications for Higgs studies at the future LHC and ILC.

  2. Top 10 Products of 2011

    ERIC Educational Resources Information Center

    American School & University, 2011

    2011-01-01

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

  3. Positronium ions and molecules

    NASA Technical Reports Server (NTRS)

    Ho, Y. K.

    1990-01-01

    Recent theoretical studies on positronium ions and molecules are discussed. A positronium ion is a three particle system consisting of two electrons in singlet spin state, and a positron. Recent studies include calculations of its binding energy, positron annihilation rate, and investigations of its doubly excited resonant states. A positronium molecule is a four body system consisting of two positrons and two electrons in an overall singlet spin state. The recent calculations of its binding energy against the dissociation into two positronium atoms, and studies of auto-detaching states in positronium molecules are discussed. These auto-dissociating states, which are believed to be part of the Rydberg series as a result of a positron attaching to a negatively charged positronium ion, Ps-, would appear as resonances in Ps-Ps scattering.

  4. Molecules on ice

    SciTech Connect

    Clary, D.C.

    1996-03-15

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

  5. Towards single molecule switches.

    PubMed

    Zhang, Jia Lin; Zhong, Jian Qiang; Lin, Jia Dan; Hu, Wen Ping; Wu, Kai; Xu, Guo Qin; Wee, Andrew T S; Chen, Wei

    2015-05-21

    The concept of using single molecules as key building blocks for logic gates, diodes and transistors to perform basic functions of digital electronic devices at the molecular scale has been explored over the past decades. However, in addition to mimicking the basic functions of current silicon devices, molecules often possess unique properties that have no parallel in conventional materials and promise new hybrid devices with novel functions that cannot be achieved with equivalent solid-state devices. The most appealing example is the molecular switch. Over the past decade, molecular switches on surfaces have been intensely investigated. A variety of external stimuli such as light, electric field, temperature, tunneling electrons and even chemical stimulus have been used to activate these molecular switches between bistable or even multiple states by manipulating molecular conformations, dipole orientations, spin states, charge states and even chemical bond formation. The switching event can occur either on surfaces or in break junctions. The aim of this review is to highlight recent advances in molecular switches triggered by various external stimuli, as investigated by low-temperature scanning tunneling microscopy (LT-STM) and the break junction technique. We begin by presenting the molecular switches triggered by various external stimuli that do not provide single molecule selectivity, referred to as non-selective switching. Special focus is then given to selective single molecule switching realized using the LT-STM tip on surfaces. Single molecule switches operated by different mechanisms are reviewed and discussed. Finally, molecular switches embedded in self-assembled monolayers (SAMs) and single molecule junctions are addressed. PMID:25757483

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

    SciTech Connect

    Benitez, Jorge Armando; /Michigan State U.

    2009-08-01

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

  7. On symmetric and upwind TVD schemes

    NASA Technical Reports Server (NTRS)

    Yee, H. C.

    1985-01-01

    A class of explicit and implicit total variation diminishing (TVD) schemes for the compressible Euler and Navier-Stokes equations was developed. They do not generate spurious oscillations across shocks and contact discontinuities. In general, shocks can be captured within 1 to 2 grid points. For the inviscid case, these schemes are divided into upwind TVD schemes and symmetric (nonupwind) TVD schemes. The upwind TVD scheme is based on the second-order TVD scheme. The symmetric TVD scheme is a generalization of Roe's and Davis' TVD Lax-Wendroff scheme. The performance of these schemes on some viscous and inviscid airfoil steady-state calculations is investigated. The symmetric and upwind TVD schemes are compared.

  8. CAST: Contraction Algorithm for Symmetric Tensors

    SciTech Connect

    Rajbhandari, Samyam; NIkam, Akshay; Lai, Pai-Wei; Stock, Kevin; Krishnamoorthy, Sriram; Sadayappan, Ponnuswamy

    2014-09-22

    Tensor contractions represent the most compute-intensive core kernels in ab initio computational quantum chemistry and nuclear physics. Symmetries in these tensor contractions makes them difficult to load balance and scale to large distributed systems. In this paper, we develop an efficient and scalable algorithm to contract symmetric tensors. We introduce a novel approach that avoids data redistribution in contracting symmetric tensors while also avoiding redundant storage and maintaining load balance. We present experimental results on two parallel supercomputers for several symmetric contractions that appear in the CCSD quantum chemistry method. We also present a novel approach to tensor redistribution that can take advantage of parallel hyperplanes when the initial distribution has replicated dimensions, and use collective broadcast when the final distribution has replicated dimensions, making the algorithm very efficient.

  9. Multicolor Bound Soliton Molecule

    E-print Network

    Luo, Rui; Lin, Qiang

    2015-01-01

    We show a new class of bound soliton molecule that exists in a parametrically driven nonlinear optical cavity with appropriate dispersion characteristics. The composed solitons exhibit distinctive colors but coincide in time and share a common phase, bound together via strong inter-soliton four-wave mixing and Cherenkov radiation. The multicolor bound soliton molecule shows intriguing spectral locking characteristics and remarkable capability of spectrum management to tailor soliton frequencies, which may open up a great avenue towards versatile generation and manipulation of multi-octave spanning phase-locked Kerr frequency combs, with great potential for applications in frequency metrology, optical frequency synthesis, and spectroscopy.

  10. Single Molecule Manipulation

    NASA Astrophysics Data System (ADS)

    Kiang, Ching-Hwa

    2011-10-01

    Single-molecule manipulation studies open a door for a close-up investigation of complex biological interactions at the molecular level. In these studies, single biomolecules are pulled while their force response is being monitored. The process is often nonequilibrium, and interpretation of the results has been challenging. We used the atomic force microscope to pull proteins and DNA, and determined the equilibrium properties of the molecules using the recently derived nonequilibrium work theorem. I will present applications of the technique in areas ranging from fundamental biological problems such as DNA mechanics, to complex medical processes such as the mechanical activation of von Willebrand Factor, a key protein in blood coagulation.

  11. Role of 2-D periodic symmetrical nanostructures in improving efficiency of thin film solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Jiang, Liyong; Li, Xiangyin

    2016-01-01

    We systematically investigated several different nanostructures in crystalline silicon (c-Si) thin film solar cells and then proposed a brand-new structure with two dimensional (2-D) periodic dielectric cylinders on the top and annular metal columns on bottom surface to enhance the optical harvesting. The periodic symmetrical nanostructures affect the solar cell efficiency due to the grating diffraction effect of dielectric columns and surface plasmon polaritons (SPPs) effect induced by metal nanostructures at the dielectric-metal interface. About 52.1% more optical absorption and 33.3% more power conversion efficiency are obtained, and the maximum short current reaches to 33.24 mA/cm2.

  12. All-optical symmetric ternary logic gate

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay

    2010-09-01

    Symmetric ternary number (radix=3) has three logical states (1¯, 0, 1). It is very much useful in carry free arithmetical operation. Beside this, the logical operation using this type of number system is also effective in high speed computation and communication in multi-valued logic. In this literature all-optical circuits for three basic symmetrical ternary logical operations (inversion, MIN and MAX) are proposed and described. Numerical simulation verifies the theoretical model. In this present scheme the different ternary logical states are represented by different polarized state of light. Terahertz optical asymmetric demultiplexer (TOAD) based interferometric switch has been used categorically in this manuscript.

  13. Observational tests of Baryon symmetric cosmology

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1982-01-01

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

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

    PubMed

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

    2012-01-28

    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

  15. Unveiling charmonium molecules

    SciTech Connect

    Vijande, J.; Valcarce, A.

    2010-11-12

    We present a systematic and self-consistent analysis of four-quark charmonium states and applied it to study compact four-quark systems and meson-meson molecules. Our results are robust and should serve to clarify the situation of charmonium spectroscopy above the threshold production of charmed mesons.

  16. Mighty Molecule Models

    ERIC Educational Resources Information Center

    Brown, Tom; Rushton, Greg; Bencomo, Marie

    2008-01-01

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

  17. Complex Organic Interstellar Molecules

    E-print Network

    van Dishoeck, Ewine F.

    Complex Organic Interstellar Molecules Eric Herbst1 and Ewine F. van Dishoeck2 1 Departments complex by astronomers if not by chemists, all contain the element carbon and so can be called organic and a solid phase of tiny dust particles. The dense interstellar matter can be found in small individual

  18. The Science of Molecules

    ERIC Educational Resources Information Center

    Flory, Paul J.

    1974-01-01

    The author maintains that chemistry has a key role as the science of molecules and rejects the concept of chemistry as a branch of physics. The scope of chemistry, the philosophies underlying its practice, and the teaching of the subject also are discussed. (DT)

  19. Diversity in Biological Molecules

    ERIC Educational Resources Information Center

    Newbury, H. John

    2010-01-01

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

  20. Electron beams of cylindrically symmetric spin polarization

    E-print Network

    Yan Wang; Chun-Fang Li

    2011-04-24

    Cylindrically symmetric electron beams in spin polarization are reported for the first time. They are shown to be the eigen states of total angular momentum in the $z$ direction. But they are neither the eigen states of spin nor the eigen states of orbital angular momentum in that direction.

  1. Super-symmetric informationally complete measurements

    NASA Astrophysics Data System (ADS)

    Zhu, Huangjun

    2015-11-01

    Symmetric informationally complete measurements (SICs in short) are highly symmetric structures in the Hilbert space. They possess many nice properties which render them an ideal candidate for fiducial measurements. The symmetry of SICs is intimately connected with the geometry of the quantum state space and also has profound implications for foundational studies. Here we explore those SICs that are most symmetric according to a natural criterion and show that all of them are covariant with respect to the Heisenberg-Weyl groups, which are characterized by the discrete analog of the canonical commutation relation. Moreover, their symmetry groups are subgroups of the Clifford groups. In particular, we prove that the SIC in dimension 2, the Hesse SIC in dimension 3, and the set of Hoggar lines in dimension 8 are the only three SICs up to unitary equivalence whose symmetry groups act transitively on pairs of SIC projectors. Our work not only provides valuable insight about SICs, Heisenberg-Weyl groups, and Clifford groups, but also offers a new approach and perspective for studying many other discrete symmetric structures behind finite state quantum mechanics, such as mutually unbiased bases and discrete Wigner functions.

  2. Conformal motions in plane symmetric static spacetimes

    E-print Network

    K. Saifullah; Shair-e-Yazdan

    2009-04-22

    In this paper, conformal motions are studied in plane symmetric static spacetimes. The general solution of conformal Killing equations and the general form of the conformal Killing vector for these spacetimes are presented. All possibilities for the existence of conformal motions in these spacetimes are exhausted.

  3. Models of helically symmetric binary systems

    E-print Network

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

    2006-05-05

    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 omega. 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 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 approximately 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.

  4. PARTITION COMPLEXES, TITS BUILDINGS AND SYMMETRIC PRODUCTS

    E-print Network

    PARTITION COMPLEXES, TITS BUILDINGS AND SYMMETRIC PRODUCTS G. Z. ARONE AND W. G. DWYER Abstract. We construct a homological approximation to the par- tition complex, and identify it as the Tits building on a finite set; a Tits building is a geometric object associated to the poset of subspaces of a vector space

  5. Entanglement of completely symmetric quantum Hans Maassen

    E-print Network

    Maassen, Hans

    Entanglement of completely symmetric quantum states Hans Maassen Mark Kac Seminar, October 7, 2011 they ever will). #12;Motivation Entanglement is a central issue in quantum information theory. For example, it is the engine that will make quantum computers work (if they ever will). The study of n party-entanglement

  6. Platonic Beasts: Spherically Symmetric Multilimbed Robots

    E-print Network

    Pai, Dinesh

    of the Platonic solids, with identical multi-purpose limbs attached to its vertices. The symmetry and regularity vertex of a spherically symmetric polyhedron. The polyhedron can be one of the five Platonic solids1 -- hence the 1 Platonic solids are the only five possible regular convex polyhedra in three dimensions

  7. Miniaturized symmetrization optics for junction laser

    NASA Technical Reports Server (NTRS)

    Hammer, Jacob M. (Inventor); Kaiser, Charlie J. (Inventor); Neil, Clyde C. (Inventor)

    1982-01-01

    Miniaturized optics comprising transverse and lateral cylindrical lenses composed of millimeter-sized rods with diameters, indices-of-refraction and spacing such that substantially all the light emitted as an asymmetrical beam from the emitting junction of the laser is collected and translated to a symmetrical beam.

  8. Cylindrically symmetric solutions in conformal gravity

    SciTech Connect

    Brihaye, Y.; Verbin, Y.

    2010-06-15

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

  9. Vacuum energy for static, cylindrically symmetric systems 

    E-print Network

    Trendafilova, Cynthia

    2012-04-18

    , cylindrically symmetric system in the case of locally flat space. I then took these components and expressed them in terms of the known cylinder kernel in cylindrical coordinates. Using these results, I examine the vacuum energy density and pressure in some...

  10. Unidirectional nonlinear PT-symmetric optical structures

    SciTech Connect

    Ramezani, Hamidreza; Kottos, Tsampikos; El-Ganainy, Ramy; Christodoulides, Demetrios N.

    2010-10-15

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

  11. Symmetric irrotational water waves are traveling waves

    NASA Astrophysics Data System (ADS)

    Kogelbauer, Florian

    2015-11-01

    We show that a spatially periodic solution to the irrotational two-dimensional gravity water wave problem, with the property that the horizontal velocity component at the surface, as well as the wave profile is symmetric, necessarily defines a traveling wave. The proof makes use of maximum principles for harmonic functions and structural properties of the governing equations for nonlinear water waves.

  12. The deuterium puzzle in the symmetric universe

    NASA Technical Reports Server (NTRS)

    Leroy, B.; Nicolle, J. P.; Schatzman, E.

    1973-01-01

    An attempt was made to use deuterium abundance in the symmetric universe to prove that no nucleosynthesis takes place during annihilation and therefore neutrons were loss before nucleosynthesis. Data cover nucleosynthesis during the radiative era, cross section estimates, maximum abundance of He-4 at the end of nucleosynthesis area, and loss rate.

  13. Conformal cylindrically symmetric spacetimes in modified gravity

    NASA Astrophysics Data System (ADS)

    Türkog˜lu, Murat Metehan; Dog˜ru, Melis Ulu

    2015-11-01

    We investigate cylindrically symmetric spacetimes in the context of f(R) gravity. We firstly attain conformal symmetry of the cylindrically symmetric spacetime. We obtain solutions to use features of the conformal symmetry, field equations and their solutions for cylindrically symmetric spacetime filled with various cosmic matters such as vacuum state, perfect fluid, anisotropic fluid, massive scalar field and their combinations. With the vacuum state solutions, we show that source of the spacetime curvature is considered as Casimir effect. Casimir force for given spacetime is found using Wald’s axiomatic analysis. We expose that the Casimir force for Boulware, Hartle-Hawking and Unruh vacuum states could have attractive, repulsive and ineffective features. In the perfect fluid state, we show that matter form of the perfect fluid in given spacetime must only be dark energy. Also, we offer that potential of massive and massless scalar field are developed as an exact solution from the modified field equations. All solutions of field equations for vacuum case, perfect fluid and scalar field give a special f(R) function convenient to ?-CDM model. In addition to these solutions, we introduce conformal cylindrical symmetric solutions in the cases of different f(R) models. Finally, geometrical and physical results of the solutions are discussed.

  14. On integrability of strings on symmetric spaces

    NASA Astrophysics Data System (ADS)

    Wulff, Linus

    2015-09-01

    In the absence of NSNS three-form flux the bosonic string on a symmetric space is described by a symmetric space coset sigma-model. Such models are known to be classically integrable. We show that the integrability extends also to cases with non-zero NSNS flux (respecting the isometries) provided that the flux satisfies a condition of the form H abc H cde ˜ R abde . We then turn our attention to the type II Green-Schwarz superstring on a symmetric space. We prove that if the space preserves some supersymmetry there exists a truncation of the full superspace to a supercoset space and derive the general form of the superisometry algebra. In the case of vanishing NSNS flux the corresponding supercoset sigma-model for the string is known to be integrable. We prove that the integrability extends to the full string by augmenting the supercoset Lax connection with terms involving the fermions which are not captured by the supercoset model. The construction is carried out to quadratic order in these fermions. This proves the integrability of strings on symmetric spaces supported by RR flux which preserve any non-zero amount of supersymmetry. Finally we also construct Lax connections for some supercoset models with non-zero NSNS flux describing strings in AdS 2,3 × S 2,3 × S 2,3 × T 2,3,4 backgrounds preserving eight supersymmetries.

  15. GENERALIZED BLOCKS FOR SYMMETRIC GROUPS BURKHARD K

    E-print Network

    characters into p-blocks in terms of a combinatorial condition on the partitions labelling them. More speci of the second main theorem of blocks. Then in section 4 we construct \\basic sets", i.e. integral basesGENERALIZED BLOCKS FOR SYMMETRIC GROUPS BURKHARD K  ULSHAMMER, J#31;RN B. OLSSON, AND GEOFFREY R

  16. Are vacuum-filtrated reduced graphene oxide membranes symmetric?

    PubMed

    Tang, Bo; Zhang, Lianbin; Li, Renyuan; Wu, Jinbo; Hedhili, Mohamed Neijib; Wang, Peng

    2015-12-23

    Graphene or reduced graphene oxide (rGO) membrane-based materials are promising for many advanced applications due to their exceptional properties. One of the most widely used synthesis methods for rGO membranes is vacuum filtration of graphene oxide (GO) on a filter membrane, followed by reduction, which shows great advantages such as operational convenience and good controllability. Despite vacuum-filtrated rGO membranes being widely used in many applications, a fundamental question is overlooked: are the top and bottom surfaces of the membranes formed at the interfaces with air and with the filter membrane respectively symmetric or asymmetric? This work, for the first time, reports the asymmetry of the vacuum-filtrated rGO membranes and discloses the filter membranes' physical imprint on the bottom surface of the rGO membrane, which takes place when the filter membrane surface pores have similar dimension to GO sheets. This result points out that the asymmetric surface properties should be cautiously taken into consideration while designing the surface-related applications for GO and rGO membranes. PMID:26667828

  17. Observation of the Top Quark

    NASA Astrophysics Data System (ADS)

    Abachi, S.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adam, I.; Adams, D. L.; Adams, M.; Ahn, S.; Aihara, H.; Alitti, J.; Álvarez, G.; Alves, G. A.; Amidi, E.; Amos, N.; Anderson, E. W.; Aronson, S. H.; Astur, R.; Avery, R. E.; Baden, A.; 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.-M.; Chekulaev, S. V.; Chen, L.-P.; 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, Yu.; 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.; Grünendahl, S.; Guida, J. A.; Guida, J. M.; Guryn, W.; Gurzhiev, S. N.; Gutnikov, Y. E.; Hadley, N. J.; Haggerty, H.; Hagopian, S.; Hagopian, V.; Hahn, K. S.; Hall, R. E.; Hansen, S.; Hatcher, R.; Hauptman, J. M.; Hedin, D.; Heinson, A. P.; Heintz, U.; Hernandez-Montoya, R.; Heuring, T.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Hoftun, J. S.; Hsieh, F.; Hu, Ting; Hu, Tong; Huehn, T.; Igarashi, S.; Ito, A. S.; James, E.; Jaques, J.; Jerger, S. A.; Jiang, J. Z.-Y.; Joffe-Minor, T.; Johari, H.; Johns, K.; Johnson, M.; Johnstad, H.; Jonckheere, A.; Jöstlein, H.; Jun, S. Y.; Jung, C. K.; Kahn, S.; Kang, J. S.; Kehoe, R.; Kelly, M.; Kernan, A.; Kerth, L.; Kim, C. L.; Kim, S. K.; Klatchko, A.; Klima, B.; Klochkov, B. I.; Klopfenstein, C.; Klyukhin, V. I.; Kochetkov, V. I.; Kohli, J. M.; Koltick, D.; Kostritskiy, A. V.; Kotcher, J.; Kourlas, J.; Kozelov, A. V.; Kozlovski, E. A.; Krishnaswamy, M. R.; Krzywdzinski, S.; Kunori, S.; Lami, S.; Landsberg, G.; Lanou, R. E.; Lebrat, J.-F.; Lee-Franzini, J.; Leflat, A.; Li, H.; Li, J.; Li, Y. K.; Li-Demarteau, Q. Z.; Lima, J. G.; Lincoln, D.; Linn, S. L.; Linnemann, J.; Lipton, R.; Liu, Y. C.; Lobkowicz, F.; Loken, S. C.; Lökös, S.; Lueking, L.; Lyon, A. L.; Maciel, A. K.; Madaras, R. J.; Madden, R.; Mandrichenko, I. V.; Mangeot, Ph.; Mani, S.; Mansoulié, B.; Mao, H. S.; Margulies, S.; Markeloff, R.; Markosky, L.; Marshall, T.; Martin, M. I.; Marx, M.; May, B.; Mayorov, A. A.; McCarthy, R.; McKibben, T.; McKinley, J.; Melanson, H. L.; de Mello Neto, J. R.; Merritt, K. W.; Miettinen, H.; Milder, A.; Milner, C.; Mincer, A.; de Miranda, J. M.; Mishra, C. S.; Mohammadi-Baarmand, M.; Mokhov, N.; Mondal, N. K.; Montgomery, H. E.; Mooney, P.; Mudan, M.; Murphy, C.; Murphy, C. T.; Nang, F.; Narain, M.; Narasimham, V. S.; Narayanan, A.; Neal, H. A.; Negret, J. P.; Neis, E.; Nemethy, P.; Neši?, D.; Norman, D.; Oesch, L.; Oguri, V.; Oltman, E.; Oshima, N.; Owen, D.; Padley, P.; Pang, M.; Para, A.; Park, C. H.; Park, Y. M.; Partridge, R.; Parua, N.; Paterno, M.; Perkins, J.; Peryshkin, A.; Peters, M.; Piekarz, H.; Pischalnikov, Y.; Pluquet, A.; Podstavkov, V. M.; Pope, B. G.; Prosper, H. B.; Protopopescu, S.; Pušelji?, D.; Qian, J.; Quintas, P. Z.; Raja, R.; Rajagopalan, S.; Ramirez, O.; Rao, M. V.; Rapidis, P. A.; Rasmussen, L.; Read, A. L.; Reucroft, S.; Rijssenbeek, M.; Rockwell, T.; Roe, N. A.; Roldan, J. M.; Rubinov, P.; Ruchti, R.; Rusin, S.; Rutherfoord, J.; Santoro, A.; Sawyer, L.; Schamberger, R. D.; Schellman, H.; Schmid, D.; Sculli, J.; Shabalina, E.; Shaffer, C.; Shankar, H. C.; Shivpuri, R. K.; Shupe, M.; Singh, J. B.; Sirotenko, V.; Smart, W.; Smith, A.; Smith, R. P.; Snihur, R.; Snow, G. R.; Snyder, S.; Solomon, J.; Sood, P. M.; Sosebee, M.; Souza, M.; Spadafora, A. L.; Stephens, R. W.; Stevenson, M. L.; Stewart, D.; Stocker, F.; Stoianova, D. A.

    1995-04-01

    The D0 Collaboration reports on a search for the standard model top quark in pp¯ collisions at s = 1.8 TeV at the Fermilab Tevatron with an integrated luminosity of approximately 50 pb-1. We have searched for tt¯ production in the dilepton and single-lepton decay channels with and without tagging of b-quark jets. We observed 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 2×10-6 (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+19-21 (stat) +/-22 (syst) GeV/c2 and its production cross section to be 6.4+/-2.2 pb.

  18. Bacterial invasion reconstructed molecule by molecule

    SciTech Connect

    Werner, James H

    2009-01-01

    We propose to visualize the initial stages of bacterial infection of a human host cell with unmatched spatial and temporal resolution. This work will develop a new capability for the laboratory (super-resolution optical imaging), will test unresolved scientific hypotheses regarding host-pathogen interaction dynamics, and leverages state of the art 3D molecular tracking instrumentation developed recently by our group. There is much to be gained by applying new single molecule tools to the important and familiar problem of pathogen entry into a host cell. For example, conventional fluorescence microscopy has identified key host receptors, such as CD44 and {alpha}5{beta}1 integrin, that aggregate near the site of Salmonella typhimurium infection of human cells. However, due to the small size of the bacteria ({approx} 2 {micro}m) and the diffraction of the emitted light, one just sees a fluorescent 'blob' of host receptors that aggregate at the site of attachment, making it difficult to determine the exact number of receptors present or whether there is any particular spatial arrangement of the receptors that facilitates bacterial adhesion/entry. Using newly developed single molecule based super-resolution imaging methods, we will visualize how host receptors are directed to the site of pathogen adhesion and whether host receptors adopt a specific spatial arrangement for successful infection. Furthermore, we will employ our 3D molecular tracking methods to follow the injection of virulence proteins, or effectors, into the host cell by the pathogen Type III secretion system (TTSS). We expect these studies to provide mechanistic insights into the early events of pathogen infection that have here-to-fore been technically beyond our reach. Our Research Goals are: Goal 1--Construct a super-resolution fluorescence microscope and use this new capability to image the spatial distribution of different host receptors (e.g. CD44, as {alpha}5{beta}1 integrin) at the point of bacterial attachment to a human cell. Goal 2--Determine if the transport method of host cell receptors to the site of Salmonella infection depends upon their initial spatial location. We hypothesize that host receptors originally near the infection site will diffuse in the host membrane till 'caught' by the bacteria, while receptors further away from the bacteria will be driven by actin to the infection site in a highly directed fashion. Goal 3--Measure the 3D path taken by a bacterial effector to find its host counterpart. We hypothesize that bacterial effectors, after passing into the host via the TTSS, fmd their host target proteins through an un-biased diffusion process (e.g. a random walk, rather than active transport). This hypothesis will be tested on the bacterial effector SopE as it searches for its host partner, Racl.

  19. Top quark production at the Tevatron

    SciTech Connect

    Varnes, Erich W.; /Arizona U.

    2010-09-01

    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.

  20. Negative ions of polyatomic molecules.

    PubMed Central

    Christophorou, L G

    1980-01-01

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

  1. Single-molecule Nanomagnets

    E-print Network

    Jonathan R. Friedman; Myriam P. Sarachik

    2010-08-04

    Single molecule magnets straddle the classical and quantum mechanical worlds, displaying many fascinating phenomena. They may have important technological applications in information storage and quantum computation. We review the physical properties of two prototypical molecular nanomagnets, Mn_12-acetate and Fe_8: each behaves as a rigid, spin-10 object, and exhibits tunneling between up and down directions. As temperature is lowered, the spin reversal process evolves from thermal activation to pure quantum tunneling. At low temperatures, magnetic avalanches occur in which the magnetization of an entire sample rapidly reverses. We discuss the important role that symmetry-breaking fields play in driving tunneling and in producing Berry-phase interference. Recent experimental advances indicate that quantum coherence can be maintained on time scales sufficient to allow a meaningful number of quantum computing operations to be performed. Efforts are underway to create monolayers and to address and manipulate individual molecules.

  2. Molecules in Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Berdyugina, Svetlana

    2015-08-01

    Molecules probe cool matter in the Universe and various astrophysical objects. Their ability to sense magnetic fields provides new insights into magnetic properties of these objects. During the past fifteen years we have carried out a theoretical study of molecular magnetic effects such as the Zeeman, Paschen-Back and Hanle effects and their applications for inferring magnetic structures and spatial inhomogeneities on the Sun, cool stars, brown dwarfs, and exoplanets from molecular spectro-polarimetry (e.g., Berdyugina 2011). Here, we present an overview of this study and compare our theoretical predictions with recent laboratory measurements of magnetic properties of some molecules. We present also a new web-based tool to compute molecular magnetic effects and polarized spectra which is supported by the ERC Advanced Grant HotMol.

  3. Top Quark Spin Correlations - Theory

    SciTech Connect

    Parke, Stephen J.; /Fermilab

    2012-02-01

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

  4. Symmetric collective attacks for the eavesdropping of symmetric quantum key distribution

    E-print Network

    Stefano Pirandola

    2008-09-18

    We consider the collective eavesdropping of the BB84 and six-state protocols. Since these protocols are symmetric in the eigenstates of conjugate bases, we consider collective attacks having the same kind of symmetry. We then show how these symmetric collective attacks are sufficiently strong in order to minimize the Devetak-Winter rates. In fact, it is quite easy to construct simple examples able to reach the unconditionally-secure key-rates of these protocols.

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

    SciTech Connect

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

    2013-05-28

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

  6. Strange skyrmion molecules

    SciTech Connect

    Kopeliovich, Vladimir B.; Stern, Boris E.

    1997-05-20

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

  7. Characterization of dinaphthosulfoxide molecule

    NASA Astrophysics Data System (ADS)

    Uluçam, Gühergül; Okan, S. Erol; Akta?, ?aban; Ö?retmen, Gül Penbe

    2015-12-01

    Dinaphthosulfoxide has been synthesized, and confirmed by the experimental methods. The geometrical optimization of the two isomers of the molecule in their ground state was studied using density functional theory. Then, NMR and IR spectra were calculated for the optimized configurations. Analyzing the hydroxyl features in the NMR data and that of sulfoxide in IR spectra, the experimental observables are found to be in agreement with the properties of the syn isomer.

  8. Model molecules mimicking asphaltenes.

    PubMed

    Sjöblom, Johan; Simon, Sébastien; Xu, Zhenghe

    2015-04-01

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

  9. Spectroscopy of Reactive Molecules and Clusters

    NASA Astrophysics Data System (ADS)

    Johnson, Matthew Stanley

    This thesis presents spectroscopic investigations of reactive molecules and clusters. The techniques of laser excited fluorescence, infrared predissociation spectroscopy, and photoelectron spectroscopy were employed to investigate systems relating to fundamental cluster chemistry, ion solvation, and atmospheric ozone depletion. An instrument was developed to investigate van der Waals complexes of refractory elements. A pulsed laser ablation cluster source harnessed the cooling power of a supersonic free jet to condense weakly bound neutral clusters. Laser excited fluorescence was used to characterize the products of the source, which included adducts of aluminum atoms with water molecules, hydrogen, and argon. The species Al(H_2O), AlAr and AlH were identified. The infrared predissociation spectra of positive and negative cluster ions were investigated using a tandem time-of-flight instrument. In this work the photofragment yield spectrum of mass-selected I^-(H _2O) and I^-(H _2O)_2 complexes was measured between 3170 and 3800 cm^{ -1}. The dominant features in the I ^-(H_2O) spectra were assigned as a hydrogen bonded OH stretch and a free OH stretch. Ab initio calculations were used to aid in spectral assignment and for geometrical information concerning I ^-(H_2O). Absorptions in the iodide water dimer cluster are attributed to a symmetric and an antisymmetric bonded OH stretch, and a free OH stretch. Chlorine nitrate is a key reservoir of stratospheric chlorine, and as such its photolysis branching ratio is crucial to partitioning of species involved with stratospheric ozone depletion. The He(I) photoelectron spectrum of chlorine nitrate was measured and assigned in order to understand the photodissociation behavior of chlorine nitrate. The results include the ionization potential of the molecule (10.86 eV), and the assignment of the first ionization peak to a nonbonding chlorine atomic orbital.

  10. High performance Cholesky and symmetric indefinite factorizations with applications 

    E-print Network

    Hogg, Jonathan David

    2010-01-01

    The process of factorizing a symmetric matrix using the Cholesky (LLT ) or indefinite (LDLT ) factorization of A allows the efficient solution of systems Ax = b when A is symmetric. This thesis describes the development ...

  11. The E3 Ubiquitin-Ligase Bmi1/Ring1A Controls the Proteasomal Degradation of Top2? Cleavage Complex – A Potentially New Drug Target

    PubMed Central

    Alchanati, Iris; Teicher, Carmit; Cohen, Galit; Shemesh, Vivian; Barr, Haim M.; Nakache, Philippe; Ben-Avraham, Danny; Idelevich, Anna; Angel, Itzchak; Livnah, Nurit; Tuvia, Shmuel; Reiss, Yuval; Taglicht, Daniel; Erez, Omri

    2009-01-01

    Background The topoisomerases Top1, Top2? and Top2? are important molecular targets for antitumor drugs, which specifically poison Top1 or Top2 isomers. While it was previously demonstrated that poisoned Top1 and Top2? are subject to proteasomal degradation, this phenomena was not demonstrated for Top2?. Methodology/Principal Findings We show here that Top2? is subject to drug induced proteasomal degradation as well, although at a lower rate than Top2?. Using an siRNA screen we identified Bmi1 and Ring1A as subunits of an E3 ubiquitin ligase involved in this process. We show that silencing of Bmi1 inhibits drug-induced Top2? degradation, increases the persistence of Top2?-DNA cleavage complex, and increases Top2 drug efficacy. The Bmi1/Ring1A ligase ubiquitinates Top2? in-vitro and cellular overexpression of Bmi1 increases drug induced Top2? ubiquitination. A small-molecular weight compound, identified in a screen for inhibitors of Bmi1/Ring1A ubiquitination activity, also prevents Top2? ubiquitination and drug-induced Top2? degradation. This ubiquitination inhibitor increases the efficacy of topoisomerase 2 poisons in a synergistic manner. Conclusions/Significance The discovery that poisoned Top2? is undergoing proteasomal degradation combined with the involvement of Bmi1/Ring1A, allowed us to identify a small molecule that inhibits the degradation process. The Bmi1/Ring1A inhibitor sensitizes cells to Top2 drugs, suggesting that this type of drug combination will have a beneficial therapeutic outcome. As Bmi1 is also a known oncogene, elevated in numerous types of cancer, the identified Bmi1/Ring1A ubiquitin ligase inhibitors can also be potentially used to directly target the oncogenic properties of Bmi1. PMID:19956605

  12. Self-assembly of ?-6T Molecule on Ag(100) and Related STM Induced Luminescence

    NASA Astrophysics Data System (ADS)

    Chen, Liu-guo; Zhang, Chao; Zhang, Rui; Dong, Zhen-chao

    2011-12-01

    We have investigated the self-assembly and light emission properties of organic ?-sexithiophene (?-6T) molecules on Ag(100) under different coverage by scanning tunneling microscopy (STM). At very low coverage, the ?-6T molecules form a unique enantiomer by grouping four molecules into a windmill supermolecular structure. As the coverage is increased, ?-6T molecules tend to pack side by side into a denser stripe structure. Further increase of the coverage will lead to the layer-by-layer growth of molecules on Ag(100) with the lower-layer stripe pattern serving as a template. Molecular fluorescence for ?-6T molecules on Ag(100) at a coverage of five monolayers has been detected by light excitations, which indicates a well decoupled electronic states for the top-layer ?-6T molecules. However, the STM induced luminescent spectra for the same sample reveal only plasmonic-like emission. The absence of intramolecular fluorescence in this case suggests that the electronic decoupling is not a sufficient condition for generating photon emission from molecules. For intramolecular fluorescence to occur, the orientation of the dynamic dipole moment of molecules and the energy-level alignment at the molecule-metal interface are also important so that molecules can be effectively excited through efficient dipolar coupling with local plasmons and by injecting holes into the molecules.

  13. Ultra-cold molecule production.

    SciTech Connect

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

    2005-12-01

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

  14. Top Internal Concerns for 1991.

    ERIC Educational Resources Information Center

    Meyerson, Joel W.; Johnson, Sandra L.

    1991-01-01

    The top internal issues identified by leaders in higher education management as most likely to influence colleges' financial and competitive positions in the near future include tuition policy and financing, capital renewal and replacement, research funding, planning and budgeting, and cost and productivity. (Author/MSE)

  15. The Top 100: Associate Rankings

    ERIC Educational Resources Information Center

    Blackmon, Olivia

    2009-01-01

    This year, Diverse has added a new addition to its annual Top 100 degree producers series--recognizing, with this edition, the institutions that award the most associate degrees to students of color. More than half of minority undergraduate students start their degree quest at a community college with 55 percent of all Hispanic and Native American…

  16. Kowalevski top in quantum mechanics

    SciTech Connect

    Matsuyama, A.

    2013-09-15

    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. -- Highlights: •Quantum spectra of the Kowalevski top are calculated. •Semiclassical quantization is carried out by the EBK formulation. •Quantum states are labeled by the semiclassical integer quantum numbers. •Multiplicity of the classical torus makes the spectra nearly degenerate. •Symmetries, quantum numbers and near-degenerate spectra are closely related.

  17. Top quark mass and kinematics

    SciTech Connect

    Barberis, Emanuela; /Northeastern U.

    2006-05-01

    A summary of the results on the measurement of the Top Quark mass and the study of the kinematics of the t{bar t} system at the Tevatron collider is presented here. Results from both the CDF and D0 collaborations are reported.

  18. The Top STEM Degree Producers

    ERIC Educational Resources Information Center

    Diverse: Issues in Higher Education, 2012

    2012-01-01

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

  19. 14 CFR 23.331 - Symmetrical flight conditions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Symmetrical flight conditions. 23.331... Flight Loads § 23.331 Symmetrical flight conditions. (a) The appropriate balancing horizontal tail load... inertia loads corresponding to any of the symmetrical flight conditions specified in §§ 23.333 through...

  20. 14 CFR 23.331 - Symmetrical flight conditions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Symmetrical flight conditions. 23.331... Flight Loads § 23.331 Symmetrical flight conditions. (a) The appropriate balancing horizontal tail load... inertia loads corresponding to any of the symmetrical flight conditions specified in §§ 23.333 through...

  1. Pyramid diffraction in parity-time-symmetric optical lattices

    E-print Network

    Yang, Jianke

    Pyramid diffraction in parity-time-symmetric optical lattices Sean Nixon and Jianke Yang in two-dimensional parity-time-symmetric optical lattices near the phase tran- sition point of light beams in PT -symmetric optical lattices is taken as iz 2 Vx; y jj2 0; (1) where z

  2. Representation theory of symmetric groups, wreath products and related algebras.

    E-print Network

    Banaji,. Murad

    Representation theory of symmetric groups, wreath products and related algebras. The representation theory of symmetric groups has been studied for over a century. Although mathematicians have a good of the wreath product of two symmetric groups sometimes arise when studying the representation theory

  3. Boosted top quarks and jet structure

    NASA Astrophysics Data System (ADS)

    Schätzel, Sebastian

    2015-09-01

    The Large Hadron Collider is the first particle accelerator that provides high enough energy to produce large numbers of boosted top quarks. The decay products of these top quarks are confined to a cone in the top quark flight direction and can be clustered into a single jet. Top quark reconstruction then amounts to analysing the structure of the jet and looking for subjets that are kinematically compatible with top quark decay. Many techniques have been developed in this context to identify top quarks in a large background of non-top jets. This article reviews the results obtained using data recorded in the years 2010-2012 by the experiments ATLAS and CMS. Studies of Standard Model top quark production and searches for new massive particles that decay to top quarks are presented.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  5. Error correction and symmetrization in quantum computers

    E-print Network

    Asher Peres

    1996-11-26

    Errors in quantum computers are of two kinds: sudden perturbations to isolated qubits, and slow random drifts of all the qubits. The latter may be reduced, but not eliminated, by means of symmetrization, namely by using many replicas of the computer, and forcing their joint quantum state to be completely symmetric. On the other hand, isolated errors can be corrected by quantum codewords that represent a logical qubit in a redundant way, by several physical qubits. If one of the physical qubits is perturbed, for example if it gets entangled with an unknown environment, there still is enough information encoded in the other physical qubits to restore the logical qubit, and disentangle it from the environment. The recovery procedure may consist of unitary operations, without the need of actually identifying the error.

  6. Young—Capelli symmetrizers in superalgebras†

    PubMed Central

    Brini, Andrea; Teolis, Antonio G. B.

    1989-01-01

    Let Supern[U [unk] V] be the nth homogeneous subspace of the supersymmetric algebra of U [unk] V, where U and V are Z2-graded vector spaces over a field K of characteristic zero. The actions of the general linear Lie superalgebras pl(U) and pl(V) span two finite-dimensional K-subalgebras B and [unk] of EndK(Supern[U [unk] V]) that are the centralizers of each other. Young—Capelli symmetrizers and Young—Capelli *-symmetrizers give rise to K-linear bases of B and [unk] containing orthogonal systems of idempotents; thus they yield complete decompositions of B and [unk] into minimal left and right ideals, respectively. PMID:16594014

  7. Nonlinear electrodynamics as a symmetric hyperbolic system

    NASA Astrophysics Data System (ADS)

    Abalos, Fernando; Carrasco, Federico; Goulart, Érico; Reula, Oscar

    2015-10-01

    Nonlinear theories generalizing Maxwell's electromagnetism and arising from a Lagrangian formalism have dispersion relations in which propagation planes factor into null planes corresponding to two effective metrics which depend on the pointwise values of the electromagnetic field. These effective Lorentzian metrics share the null (generically two) directions of the electromagnetic field. We show that the theory is symmetric hyperbolic if and only if the cones these metrics give rise to have a nonempty intersection, namely, that there exist families of symmetrizers in the sense of Geroch [26] which are positive definite for all covectors in the interior of the cones intersection. Thus, for these theories, the initial value problem is well posed. We illustrate the power of this approach with several nonlinear models of physical interest such as Born-Infeld, Gauss-Bonnet, and Euler-Heisenberg.

  8. Spherically Symmetric Solutions of Light Galileon

    NASA Astrophysics Data System (ADS)

    Momeni, D.; Houndjo, M. J. S.; Güdekli, E.; Rodrigues, M. E.; Alvarenga, F. G.; Myrzakulov, R.

    2015-08-01

    We have been studied the model of light Galileon with translational shift symmetry ? ? ? + c. The matter Lagrangian is presented in the form L_{? }= -? (partial ? )2+? G^{? ? }partial _{? }? partial _{? }? . We have been addressed two issues: the first is that, we have been proven that, this type of Galileons belong to the modified matter-curvature models of gravity in type of f(R,R^{? ? }T_{? ? }m). Secondly, we have been investigated exact solution for spherically symmetric geometries in this model. We have been found an exact solution with singularity at r = 0 in null coordinates. We have been proven that the solution has also a non-divergence current vector norm. This solution can be considered as an special solution which has been investigated in literature before, in which the Galileon's field is non-static (time dependence). Our scalar-shift symmetrized Galileon has the simple form of ? = t, which it is remembered by us dilaton field.

  9. Binary switching in a ‘symmetric' potential landscape

    PubMed Central

    Roy, Kuntal; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

    2013-01-01

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

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

    SciTech Connect

    Lee, Myoung-Jae; Jung, Young-Dae

    2015-02-15

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

  11. Tilted Cylindrically Symmetric Self-Similar Solutions

    E-print Network

    M. Sharif; Sajid Sultan

    2009-05-16

    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.

  12. Expansion-free Cylindrically Symmetric Models

    E-print Network

    M. Sharif; Z. Yousaf

    2013-10-30

    This paper investigates cylindrically symmetric distribution of an-isotropic fluid under the expansion-free condition, which requires the existence of vacuum cavity within the fluid distribution. We have discussed two family of solutions which further provide two exact models in each family. Some of these solutions satisfy Darmois junction condition while some show the presence of thin shell on both boundary surfaces. We also formulate a relation between the Weyl tensor and energy density.

  13. PT-Symmetric Quantum Liouvillean Dynamics

    NASA Astrophysics Data System (ADS)

    Prosen, Tomaž

    2012-08-01

    We discuss a combination of unitary and antiunitary symmetry of quantum Liouvillean dynamics, in the context of open quantum systems, which implies a D2 symmetry of the complex Liouvillean spectrum. For sufficiently weak system-bath coupling, it implies a uniform decay rate for all coherences, i.e., off-diagonal elements of the system’s density matrix taken in the eigenbasis of the Hamiltonian. As an example, we discuss symmetrically boundary driven open XXZ spin 1/2 chains.

  14. Yangian symmetric correlators, R operators and amplitudes

    NASA Astrophysics Data System (ADS)

    Kirschner, R.

    2014-11-01

    Yangian symmetric correlators can be constructed by the action of Yang-Baxter R operators on trivial basic correlators. The example of a four-point correlator is given in two representations and the construction of the completely connected N point correlator is described. The helicity representation is dicussed and the relation of the four-point correlator to tree-level scattering amplitudes is shown.

  15. Wave equation on spherically symmetric Lorentzian metrics

    SciTech Connect

    Bokhari, Ashfaque H.; Al-Dweik, Ahmad Y.; Zaman, F. D.; Kara, A. H.; Karim, M.

    2011-06-15

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

  16. Intense pumping and time- and frequency-resolved CARS for driving and tracking structural deformation and recovery of liquid nitromethane molecules

    NASA Astrophysics Data System (ADS)

    Wang, Chang; Wu, Hong-lin; Song, Yun-fei; He, Xing; Yang, Yan-qiang; Tan, Duo-wang

    2015-11-01

    A modified CARS technique with an intense nonresonant femtosecond laser is presented to drive the structural deformation of liquid nitromethane molecules and track their structural relaxation process. The CARS spectra reveal that the internal rotation of the molecule can couple with the CN symmetric stretching vibration and the molecules undergo ultrafast structural deformation of the CH3 groups from 'opened umbrella' to 'closed umbrella' shape, and then experience a structural recovery process within 720 fs.

  17. Experimental and theoretical studies of plasmon-molecule interactions.

    PubMed

    Chen, Hanning; Schatz, George C; Ratner, Mark A

    2012-09-01

    Plasmon-molecule interactions are widely believed to involve photo-induced interferences between the localized excitation of individual electrons in molecules and the large collective excitation of conduction electrons in metal particles. The intrinsic multi-scale characteristics of plasmon-molecule interactions not only offer great opportunities for realizing precise top-down control of the optical properties of individual molecules, but also allow for accurate bottom-up manipulation of light polarization and propagation as a result of molecular excitation. However, the temporal and spatial complexity of plasmon-molecule experiments severely limits our interpretation and understanding of interactions that have important applications in dye-sensitized solar cells, single-molecule detectors, photoconductive molecular electronics, all-optical switching and photo-catalytic water splitting. This review aims to outline recent progress in experimental practice and theory for probing and exploiting the subtle coupling between discrete molecular orbitals and continuous metallic bands. For each experimental technique or theoretical model, the fundamental mechanisms and relevant applications are discussed in detail with specific examples. In addition, the experimental validation of theoretical models and the computational design of functional devices are both highlighted. Finally, a brief summary is presented together with an outlook for potential future directions of this emerging interdisciplinary research field. PMID:22935744

  18. Weyl symmetric structure of QCD vacuum

    E-print Network

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

    2012-09-12

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

  19. Spherically symmetric thick branes cosmological evolution

    NASA Astrophysics Data System (ADS)

    Bernardini, A. E.; Cavalcanti, R. T.; da Rocha, Roldão

    2015-01-01

    Spherically symmetric time-dependent solutions for the 5D system of a scalar field canonically coupled to gravity are obtained and identified as an extension of recent results obtained by Ahmed et al. (JHEP 1404:061. arXiv:1312.3576 [hep-th], 2014). The corresponding cosmology of models with regularized branes generated by such a 5D scalar field scenario is also investigated. It has been shown that the anisotropic evolution of the warp factor and consequently the Hubble like parameter are both driven by the radial coordinate on the brane, which leads to an emergent thick brane-world scenario with spherically symmetric time dependent warp factor. Meanwhile, the separability of variables depending on fifth dimension, , which is exhibited by the equations of motion, allows one to recover the extra dimensional profiles obtained in Ahmed et al. (2014), namely the extra dimensional part of the scale (warp) factor and the scalar field dependence on . Therefore, our results are mainly concerned with the time dependence of a spherically symmetric warp factor. Besides evincing possibilities for obtaining asymmetric stable brane-world scenarios, the extra dimensional profiles here obtained can also be reduced to those ones investigated in Ahmed et al. (2014).

  20. Top quark studies at hadron colliders

    SciTech Connect

    Sinervo, P.K.

    1997-01-01

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

  1. Playing with molecules.

    PubMed

    Toon, Adam

    2011-12-01

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

  2. Top Quark Production at the LHC

    E-print Network

    Francesco Spanò; for the ATLAS; CMS collaborations

    2011-12-16

    Top quark production in proton proton collisions at the Large Hadron Collider (LHC) is reviewed using data collected by the ATLAS and CMS detectors. Most recent results on searches for new physics related to top quark production mechanism are included.

  3. Single top at the Tevatron

    SciTech Connect

    Taffard, Anyes; /Illinois U., Urbana

    2005-11-01

    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.

  4. Thermoelectric Outer Planets Spacecraft (TOPS)

    NASA Technical Reports Server (NTRS)

    1973-01-01

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

  5. Top quark electromagnetic dipole moments

    NASA Astrophysics Data System (ADS)

    Bouzas, Antonio O.; Larios, F.

    2015-11-01

    The magnetic and electric dipole moments of the top quark are constrained indirectly by the Br(B ? Xs?) and the ACP(B ? Xs?) measurements. They can also be tested by top quark production and decay processes. The recent measurement of production by CDF are used to set direct constraints. The B ? Xs? measurements by themselves define an allowed parameter region that sets up stringent constraints on both dipole moments. The measurement by CDF has a ? 37% error that is too large to set any competitive bounds, for which a much lower 5% error would be required. For the LHC it is found that with its higher energy the same measurement could indeed further constrain the allowed parameter region given by the B ? Xs? measurement [1]. In addition, the proposed LHeC experiment (electron- proton) could provide even more stringent constraints than the LHC via the photoproduction channel [2].

  6. Single-molecule diodes with high rectification ratios through environmental control.

    PubMed

    Capozzi, Brian; Xia, Jianlong; Adak, Olgun; Dell, Emma J; Liu, Zhen-Fei; Taylor, Jeffrey C; Neaton, Jeffrey B; Campos, Luis M; Venkataraman, Latha

    2015-06-01

    Molecular electronics aims to miniaturize electronic devices by using subnanometre-scale active components. A single-molecule diode, a circuit element that directs current flow, was first proposed more than 40?years ago and consisted of an asymmetric molecule comprising a donor-bridge-acceptor architecture to mimic a semiconductor p-n junction. Several single-molecule diodes have since been realized in junctions featuring asymmetric molecular backbones, molecule-electrode linkers or electrode materials. Despite these advances, molecular diodes have had limited potential for applications due to their low conductance, low rectification ratios, extreme sensitivity to the junction structure and high operating voltages. Here, we demonstrate a powerful approach to induce current rectification in symmetric single-molecule junctions using two electrodes of the same metal, but breaking symmetry by exposing considerably different electrode areas to an ionic solution. This allows us to control the junction's electrostatic environment in an asymmetric fashion by simply changing the bias polarity. With this method, we reliably and reproducibly achieve rectification ratios in excess of 200 at voltages as low as 370?mV using a symmetric oligomer of thiophene-1,1-dioxide. By taking advantage of the changes in the junction environment induced by the presence of an ionic solution, this method provides a general route for tuning nonlinear nanoscale device phenomena, which could potentially be applied in systems beyond single-molecule junctions. PMID:26005998

  7. Single-molecule diodes with high rectification ratios through environmental control

    NASA Astrophysics Data System (ADS)

    Capozzi, Brian; Xia, Jianlong; Adak, Olgun; Dell, Emma J.; Liu, Zhen-Fei; Taylor, Jeffrey C.; Neaton, Jeffrey B.; Campos, Luis M.; Venkataraman, Latha

    2015-06-01

    Molecular electronics aims to miniaturize electronic devices by using subnanometre-scale active components. A single-molecule diode, a circuit element that directs current flow, was first proposed more than 40?years ago and consisted of an asymmetric molecule comprising a donor-bridge-acceptor architecture to mimic a semiconductor p-n junction. Several single-molecule diodes have since been realized in junctions featuring asymmetric molecular backbones, molecule-electrode linkers or electrode materials. Despite these advances, molecular diodes have had limited potential for applications due to their low conductance, low rectification ratios, extreme sensitivity to the junction structure and high operating voltages. Here, we demonstrate a powerful approach to induce current rectification in symmetric single-molecule junctions using two electrodes of the same metal, but breaking symmetry by exposing considerably different electrode areas to an ionic solution. This allows us to control the junction's electrostatic environment in an asymmetric fashion by simply changing the bias polarity. With this method, we reliably and reproducibly achieve rectification ratios in excess of 200 at voltages as low as 370?mV using a symmetric oligomer of thiophene-1,1-dioxide. By taking advantage of the changes in the junction environment induced by the presence of an ionic solution, this method provides a general route for tuning nonlinear nanoscale device phenomena, which could potentially be applied in systems beyond single-molecule junctions.

  8. Adsorption of symmetric random copolymer onto symmetric random surface: the annealed case

    E-print Network

    A. A. Polotsky

    2015-06-12

    Adsorption of a symmetric (AB) random copolymer (RC) onto a symmetric (ab) random heterogeneous surface (RS) is studied in the annealed approximation by using a two-dimensional partially directed walk model of the polymer. We show that in the symmetric case, the expected a posteriori compositions of the RC and the RS have correct values (corresponding to their a priori probabilities) and do not change with the temperature, whereas second moments of monomers and sites distributions in the RC and RS change. This indicates that monomers and sites do not interconvert but only rearrange in order to provide better matching between them and, as a result, a stronger adsorption of the RC on the RS. However, any violation of the system symmetry shifts equilibrium towards the major component and/or more favorable contacts and leads to interconversion of monomers and sites.

  9. Cloud-top parameters - A hail indicator

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  10. Heavy flavour physics from top to bottom

    SciTech Connect

    Paulini, M.; CDF and D0 Collaborations

    1997-01-01

    We review the status of heavy flavour physics at the Fermilab Tevatron collider by summarizing recent top quark and B physics results from CDF and D0. In particular we discuss the measurement of the top quark mass and top production cross section as well as B meson lifetimes and time dependent B{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.

  11. Heavy flavour physics from top to bottom

    SciTech Connect

    Paulini, M.; CDF and D0 Collaboration

    1998-02-01

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

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

    SciTech Connect

    Bae, Soo Kyung; Gwak, Jungsug; Song, Im-Sook; Park, Hyung-Soon; Oh, Sangtaek

    2011-05-27

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

  13. Effect of the Symmetry of H2 Molecules on their Rotations around an OCS Molecule in Superfluid 4He Droplets

    NASA Astrophysics Data System (ADS)

    Grebenev, Slava; Sartakov, Boris; Toennies, J. Peter; Vilesov, Andrej

    2002-11-01

    The infrared spectra of OCS-(H2)n clusters in cold (0.15K) superfluid 4He droplets coated with 3He exhibit resolved rotational bands for each n up to n=8 para-H2 (pH2) or ortho-D2 (oD2) molecules. An analysis of the different Q-branch intensities based on the different spin symmetries of pH2 and oD2 indicates the formation of symmetric 5- or 6-membered rings around the linear carbonyl sulfide (OCS) chromophore. The rings of distinguishable oD2 are found to undergo axial rotations, whereas for 6 pH2 molecules the symmetry-allowed rotational levels lie too high to be excited at the 0.15K droplet temperatures.

  14. Top quark physics expectations at the LHC

    E-print Network

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

    2008-10-22

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

  15. Top Mass Measurements at the Tevatron

    E-print Network

    M. H. L. S. Wang

    2009-04-02

    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 mtop=172.6+-1.4 GeV.

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

    DOEpatents

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

    2008-06-24

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

  17. Electron-excited molecule interactions

    SciTech Connect

    Christophorou, L.G. Tennessee Univ., Knoxville, TN . Dept. of Physics)

    1991-01-01

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

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

    SciTech Connect

    Wei, Pengjiang; Croënne, Charles; Tak Chu, Sai; Li, Jensen

    2014-03-24

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

  19. Emerging small molecule drugs.

    PubMed

    Colin, Sophie; Chinetti-Gbaguidi, Giulia; Kuivenhoven, Jan A; Staels, Bart

    2015-01-01

    Dyslipidaemia is a major risk factor for cardiovascular diseases. Pharmacological lowering of LDL-C levels using statins reduces cardiovascular risk. However, a substantial residual risk persists especially in patients with type 2 diabetes mellitus. Because of the inverse association observed in epidemiological studies of HDL-C with the risk for cardiovascular diseases, novel therapeutic strategies to raise HDL-C levels or improve HDL functionality are developed as complementary therapy for cardiovascular diseases. However, until now most therapies targeting HDL-C levels failed in clinical trials because of side effects or absence of clinical benefits. This chapter will highlight the emerging small molecules currently developed and tested in clinical trials to pharmacologically modulate HDL-C and functionality including new CETP inhibitors (anacetrapib, evacetrapib), novel PPAR agonists (K-877, CER-002, DSP-8658, INT131 and GFT505), LXR agonists (ATI-111, LXR-623, XL-652) and RVX-208. PMID:25523004

  20. Biochips - Can molecules compute?

    NASA Astrophysics Data System (ADS)

    Tucker, J. B.

    1984-02-01

    In recent years the possibility has been considered to build 'biochip' computers, in which the silicon transistors of present machines would be replaced by large organic molecules or genetically engineered proteins. Two major advantages of such biochips over current devices would be related to vastly increased densities of computing elements, and entirely new styles of data processing, suited to such high-level tasks as pattern recognition and context-dependent analysis. The limitations of the semiconductor chip with respect to the density of elementary units due to size considerations and heat development could be overcome by making use of molecular switches. Attention is given to soliton switching, soliton logic, bulk molecular devices, analog biochips, 'intelligent' switches based on the employment of enzymes, robot vision, questions of biochip fabrication, protein engineering, and a strategy for the development of biochips.

  1. Molecules in the Spotlight

    SciTech Connect

    Cryan, James

    2010-01-26

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

  2. Forces in molecules.

    PubMed

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

    2007-01-01

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

  3. 2d PDE Linear Symmetric Matrix Solver

    Energy Science and Technology Software Center (ESTSC)

    1983-10-01

    ICCG2 (Incomplete Cholesky factorized Conjugate Gradient algorithm for 2d symmetric problems) was developed to solve a linear symmetric matrix system arising from a 9-point discretization of two-dimensional elliptic and parabolic partial differential equations found in plasma physics applications, such as resistive MHD, spatial diffusive transport, and phase space transport (Fokker-Planck equation) problems. These problems share the common feature of being stiff and requiring implicit solution techniques. When these parabolic or elliptic PDE''s are discretized withmore »finite-difference or finite-element methods,the resulting matrix system is frequently of block-tridiagonal form. To use ICCG2, the discretization of the two-dimensional partial differential equation and its boundary conditions must result in a block-tridiagonal supermatrix composed of elementary tridiagonal matrices. The incomplete Cholesky conjugate gradient algorithm is used to solve the linear symmetric matrix equation. Loops are arranged to vectorize on the Cray1 with the CFT compiler, wherever possible. Recursive loops, which cannot be vectorized, are written for optimum scalar speed. For matrices lacking symmetry, ILUCG2 should be used. Similar methods in three dimensions are available in ICCG3 and ILUCG3. A general source containing extensions and macros, which must be processed by a pre-compiler to obtain the standard FORTRAN source, is provided along with the standard FORTRAN source because it is believed to be more readable. The pre-compiler is not included, but pre-compilation may be performed by a text editor as described in the UCRL-88746 Preprint.« less

  4. Symmetrical band-pass loudspeaker systems

    NASA Astrophysics Data System (ADS)

    Matusiak, Grzegorz Piotr

    2001-12-01

    Loudspeaker systems are analyzed in a doctoral dissertation. The dissertation concerns loudspeaker systems, which are known as subwoofers or band-pass loudspeaker systems. Their advantages include: high- quality sound reproduction in the low-frequency range, small dimensions, small nonlinear distortions and the fact that they can be placed anywhere in a room or car. Band-pass loudspeaker systems are used widely in the so- called Home Theatre as well as to provide sound in cinema, theatre, concert, discotheque, opera, operetta, philharmonic and amphitheater halls, at open-air concerts, and so on. Various designs are mass-produced by a large number of manufacturers. The study covers an analysis of band-pass loudspeaker systems to which the frequency transformation, i.e. the reactance transformation, has been applied. Since this is a symmetrical transformation, amplitude frequency responses of the studied band-pass systems are also symmetrical (logarithmic scale of a frequency). As a result, the high-pass loudspeaker system design method, known as the Thiele-Small, Benson analysis, can be employed. The investigations include the formulation of band-pass system equations (fourth, sixth and eighth-order polynomials) and the subsequent derivation of relations for the calculation of system parameters. The obtained results enable the calculation of optimum designs for prescribed alignments, e.g. (Chebyshev) equal-ripple, (Butterworth) maximally flat, or quasi-maximally flat (QB). The analysis covers fourth, sixth and eighth-order symmetrical systems. Eighth-order systems have been divided into three kinds according to three ways of physical realization. The doctoral dissertation includes band-pass loudspeaker systems, which can be designed with active or passive filters or without the filter. Designed systems consist of a loudspeaker whose front of a diaphragm is loaded with a Helmholtz resonator, i.e. an enclosure with a vent, which radiates sound outwards. The back is loaded with a closed-box or the Helmholtz resonator.

  5. A naturally light Higgs without light top partners

    NASA Astrophysics Data System (ADS)

    Carmona, Adrián; Goertz, Florian

    2015-05-01

    We demonstrate that the inclusion of a realistic lepton sector can relax significantly the upper bound on top partner masses in minimal composite Higgs models, induced by the lightness of the Higgs boson. To that extend, we present a comprehensive survey of the impact of different realizations of the fermion sectors on the Higgs potential, with a special emphasis on the role of the leptons. The non-negligible compositeness of the ? R in a general class of models that address the flavor structure of the lepton sector and the smallness of the corresponding FCNCs, can have a significant effect on the potential. We find that, with the ? R in the symmetric representation of SO(5), an increase in the maximally allowed mass of the lightest top partner of ? 1 TeV is possible for minimal quark setups like the MCHM5,10, without increasing the tuning. A light Higgs boson m H ˜ (100-200) GeV is a natural prediction of such models, which thus provide a new setup that can evade ultralight top partners without ad-hoc tuning in the Higgs mass. Moreover, we advocate a more minimal realization of the lepton sector than generally used in the literature, which still can avoid light partners due to its contributions to the Higgs mass in a different and very natural way, triggered by the seesaw mechanism. This allows to construct the most economical SO(5) /SO(4) composite Higgs models possible. Using both a transparent 4D approach, as well as presenting numerical results in the 5D holographic description, we demonstrate that, including leptons, minimality and naturalness do not imply light partners. Leptonic effects, not considered before, could hence be crucial for the viability of composite models.

  6. Conformal totally symmetric arbitrary spin fermionic fields

    E-print Network

    R. R. Metsaev

    2012-11-19

    Conformal totally symmetric arbitrary spin fermionic fields in flat space-time of even dimension greater than or equal to four are studied. First-derivative formulation involving Fang-Fronsdal kinetic operator for such fields is developed. Gauge invariant Lagrangian and the corresponding gauge transformations are obtained. Gauge symmetries are realized by involving the Stueckelberg and auxiliary fields. Realization of conformal algebra symmetries on the space of conformal gauge fermionic fields is obtained. On-shell degrees of freedom of the arbitrary spin conformal fermionic field are also discussed.

  7. Stability Analysis of Axial Reflection Symmetric Spacetime

    E-print Network

    M. Sharif; M. Zaeem Ul Haq Bhatti

    2015-12-08

    In this paper, we explore instability regions of non-static axial reflection symmetric spacetime with anisotropic source in the interior. We impose linear perturbation on the Einstein field equations and dynamical equations to establish the collapse equation. The effects of different physical factors like energy density and anisotropic stresses on the instability regions are studied under Newtonian and post-Newtonian limits. We conclude that stiffness parameter has a significant role in this analysis while the reflection terms increase instability ranges of non-static axial collapse.

  8. Entanglement of bosonic modes in symmetric graphs

    NASA Astrophysics Data System (ADS)

    Asoudeh, M.; Karimipour, V.

    2005-09-01

    The ground and thermal states of a quadratic Hamiltonian representing the interaction of bosonic modes or particles are always Gaussian states. We investigate the entanglement properties of these states for the case where the interactions are represented by harmonic forces acting along the edges of symmetric graphs—i.e., one-, two-, and three-dimensional rectangular lattices, mean-field clusters, and platonic solids. We determine the entanglement of formation (EOF) as a function of the interaction strength, calculate the maximum EOF in each case, and compare these values with the bounds found previously for quadratic Hamiltonians.

  9. Quantum exchange interaction of spherically symmetric plasmoids

    E-print Network

    Maxim Dvornikov

    2012-08-24

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

  10. Stability of Reflection Symmetric Collapsing Structures

    E-print Network

    M. Sharif; M. Zaeem Ul Haq Bhatti

    2015-05-25

    In this paper, we explore instability regions of non-static axial reflection symmetric spacetime with anisotropic source in the interior. We impose linear perturbation on the Einstein field equations and dynamical equations to establish the collapse equation. The effects of different physical factors like energy density and anisotropic stresses on the instability regions are studied under Newtonian and post-Newtonian limits. We conclude that stiffness parameter has a significant role in this analysis while the reflection terms increase instability ranges of non-static axial collapse.

  11. Symmetric Toeplitz-Structured Compressed Sensing Matrices

    NASA Astrophysics Data System (ADS)

    Huang, Tao; Fan, Yi-Zheng; Zhu, Ming

    2015-11-01

    How to construct a suitable measurement matrix is an important topic in compressed sensing. A significant part of the recent work is that the measurement matrices are not completely random on the entries but exhibit some considerable structures. In this paper, we proved that a symmetric Toeplitz matrix and its variant can be used as measurement matrices and recovery signal with high probability. Compared with random matrices (e.g. Gaussian and Bernoulli matrices) and some structured matrices (e.g. Toeplitz and circulant matrices), we need to generate fewer independent entries to obtain the measurement matrix while the effectiveness of the recovery keeps good.

  12. Stability analysis of axial reflection symmetric spacetime

    NASA Astrophysics Data System (ADS)

    Sharif, M.; Bhatti, M. Zaeem Ul Haq

    2016-01-01

    In this paper, we explore instability regions of non-static axial reflection symmetric spacetime with anisotropic source in the interior. We impose linear perturbation on the Einstein field equations and dynamical equations to establish the collapse equation. The effects of different physical factors like energy density and anisotropic stresses on the instability regions are studied under Newtonian and post-Newtonian limits. We conclude that stiffness parameter has a significant role in this analysis while the reflection terms increase instability ranges of non-static axial collapse.

  13. Scalar resonances in axially symmetric spacetimes

    NASA Astrophysics Data System (ADS)

    Ranea-Sandoval, Ignacio F.; Vucetich, Héctor

    2015-03-01

    We study properties of resonant solutions to the scalar wave equation in several axially symmetric spacetimes. We prove that nonaxial resonant modes do not exist neither in the Lanczos dust cylinder, the extreme (2 + 1) dimensional Bañados-Taitelboim-Zanelli (BTZ) spacetime nor in a class of simple rotating wormhole solutions. Moreover, we find unstable solutions to the wave equation in the Lanczos dust cylinder and in the r2 < 0 region of the extreme (2 + 1) dimensional BTZ spacetime, two solutions that possess closed timelike curves. Similarities with previous results obtained for the Kerr spacetime are explored.

  14. Communities and classes in symmetric fractals

    NASA Astrophysics Data System (ADS)

    Krawczyk, Ma?gorzata J.

    2015-07-01

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

  15. Quantum asymmetric cryptography with symmetric keys

    E-print Network

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

    2008-10-16

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

  16. Towards single molecule DNA sequencing

    NASA Astrophysics Data System (ADS)

    Liu, Hao

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

  17. Molecule-hugging graphene nanopores

    PubMed Central

    Garaj, Slaven; Liu, Song; Golovchenko, Jene A.; Branton, Daniel

    2013-01-01

    It has recently been recognized that solid-state nanopores in single-atomic-layer graphene membranes can be used to electronically detect and characterize single long charged polymer molecules. We have now fabricated nanopores in single-layer graphene that are closely matched to the diameter of a double-stranded DNA molecule. Ionic current signals during electrophoretically driven translocation of DNA through these nanopores were experimentally explored and theoretically modeled. Our experiments show that these nanopores have unusually high sensitivity (0.65 nA/Å) to extremely small changes in the translocating molecule’s outer diameter. Such atomically short graphene nanopores can also resolve nanoscale-spaced molecular structures along the length of a polymer, but do so with greatest sensitivity only when the pore and molecule diameters are closely matched. Modeling confirms that our most closely matched pores have an inherent resolution of ?0.6 nm along the length of the molecule. PMID:23836648

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

    E-print Network

    Cao, Jianshu

    1:1 nonlinear resonant coupling. Four characteristic modes, including symmetric normal modes, asymmetric normal modes, local modes, and quasi-local modes, are identified at different energy regimes on the vibrational dynamics of solvated molecules lead to dynamic symmetry breaking,7 normal-to-local mode

  19. Measurements of top quark properties at CDF

    SciTech Connect

    Kraan, Aafke C.; /Pennsylvania U.

    2006-11-01

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

  20. Top Quark Mass Measurements at the Tevatron

    SciTech Connect

    Ye, Zhenyu; /Fermilab

    2011-07-01

    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.

  1. Top Quark Physics at the Tevatron

    SciTech Connect

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

    2010-10-01

    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.

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

    SciTech Connect

    Chivukula, R. Sekhar; Simmons, Elizabeth H.; Coleppa, Baradhwaj; Logan, Heather E.; Martin, Adam

    2011-11-01

    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.

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

    E-print Network

    Ujjal Debnath; Mubasher Jamil

    2015-01-03

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

  4. Photonic Molecules and Spectral Engineering

    E-print Network

    Boriskina, Svetlana V.

    2010-01-01

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

  5. Aromatic molecules as spintronic devices

    SciTech Connect

    Ojeda, J. H.; Orellana, P. A.; Laroze, D.

    2014-03-14

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

  6. Cooperative activity of DNA methyltransferases for maintenance of symmetrical and non-symmetrical cytosine

    E-print Network

    Meyer, Peter

    Cooperative activity of DNA methyltransferases for maintenance of symmetrical and non of cytosine methylation in plants is controlled by three DNA methyltransferases. MET1 maintains CG methylation cooperative activity of all three DNA methyltransferases is therefore required for maintenance of both CG

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

    NASA Astrophysics Data System (ADS)

    Ueda, Yoshihiro; Duan, Renjun; Kawashima, Shuichi

    2012-07-01

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

  8. Overview of top quark measurements at ATLAS

    E-print Network

    Lucotte, Arnaud; The ATLAS collaboration

    2015-01-01

    Measurements of the QCD and EW top quark production cross sections and properties in proton-proton collisions with the ATLAS detector at the Large Hadron Collider are presented. The main focus are measurements of differential spectra of top quark pair final states, in particular fully fiducial measurements will be presented, measuring a cross section in a phase-space close to the observable region. Measurements of the top-quark mass and polarisation, as well as of the polarization of W bosons in top quark decays to probe the Wtb-vertex are presented. In addition, measurements of the spin correlation between top and anti-top quarks as well as of the top-quark charge asymmetry, which constitute important tests of QCD and are sensitive to new physics, are discussed.

  9. Rotational temperatures of molecules

    NASA Astrophysics Data System (ADS)

    Aryabhatta, Krishnanand Sinha

    Atoms and Molecules, particularly the latter are known to be sensitive to their physical environs. They have successfully been used to test/refine the available solar model atmospheres. In the present day scenario two sets of models are available viz., three dimensional models and single column homogeneous models. The former group which appears more realistic has led to a substantial reduction in abundances of certain atomic species whereas the latter is simple, easy to use and tested to explain such phenomenon as the C-L variation of continuum fluxes, line profiles of atomic lines, the rotational temperatures of molecular lines, estimates of abundances of several elements and the like. Earlier the lines of the C2 Swan system of bands was utilized by us to determine whether the then available model atmospheres explained the center of the disc and a near limb observation of the rotational temperature. The conclusion was that the center of the disc temperature could well be reproduced but not the near limb one. A suggestion was made to revise the tested model atmospheres in the upper layers. In the nineties when the controversy related to the solar abundance of Iron dominated the scene, after several exhaustive, detailed and careful scrutiny a simple solution was successfully employed to explain away and resolve the apparent controversy. This was related to the separate regions or layers of the solar atmosphere for the formation of lines due to neutral and ionized lines. A model was presented by the Belgian group of solar astronomers. The aim of the present investigation is to report and examine in detail if the model by the Belgian group can reproduce the rotational temperatures of the C2 Swan system of bands and that of the vibration - rotation bands of the CO molecules formed in two very different regions of the photospheric spectrum. A variation on the accepted values of micro-turbulence is also considered. However, it must be noted that no attempt is made to suggest that the simplified and easy to use single column model atmospheres are to be used in place of the three dimensional model again by the Belgian group.

  10. Organic Molecules in Meteorites

    NASA Astrophysics Data System (ADS)

    Martins, Zita

    2015-08-01

    Carbonaceous meteorites are primitive samples from the asteroid belt, containing 3-5wt% organic carbon. The exogenous delivery of organic matter by carbonaceous meteorites may have contributed to the organic inventory of the early Earth. The majority (>70%) of the meteoritic organic material consist of insoluble organic matter (IOM) [1]. The remaining meteoritic organic material (<30%) consists of a rich organic inventory of soluble organic compounds, including key compounds important in terrestrial biochemistry [2-4]. Different carbonaceous meteorites contain soluble organic molecules with different abundances and distributions, which may reflect the extension of aqueous alteration or thermal metamorphism on the meteorite parent bodies. Extensive aqueous alteration on the meteorite parent body may result on 1) the decomposition of ?-amino acids [5, 6]; 2) synthesis of ?- and ?-amino acids [2, 6-9]; 3) higher relative abundances of alkylated polycyclic aromatic hydrocarbons (PAHs) [6, 10]; and 4) higher L-enantiomer excess (Lee) value of isovaline [6, 11, 12].The soluble organic content of carbonaceous meteorites may also have a contribution from Fischer-Tropsch/Haber-Bosch type gas-grain reactions after the meteorite parent body cooled to lower temperatures [13, 14].The analysis of the abundances and distribution of the organic molecules present in meteorites helps to determine the physical and chemical conditions of the early solar system, and the prebiotic organic compounds available on the early Earth.[1] Cody and Alexander (2005) GCA 69, 1085. [2] Cronin and Chang (1993) in: The Chemistry of Life’s Origin. pp. 209-258. [3] Martins and Sephton (2009) in: Amino acids, peptides and proteins in organic chemistry. pp. 1-42. [4] Martins (2011) Elements 7, 35. [5] Botta et al. (2007) MAPS 42, 81. [6] Martins et al. (2015) MAPS, in press. [7] Cooper and Cronin (1995) GCA 59, 1003. [8] Glavin et al. (2006) MAPS. 41, 889. [9] Glavin et al. (2011) MAPS 45, 1948. [10] Elsila et al. (2005) GCA 5, 1349. [11] Glavin and Dworkin (2009) PNAS 106, 5487. [12] Pizzarello et al. (2003) GCA 67, 1589. [13] Chan et al. (2012) MAPS. 47, 1502. [14] Burton et al. (2011) MAPS 46, 1703.

  11. Integrable deformations of strings on symmetric spaces

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  12. Rotationally symmetric operators for surface interpolation

    SciTech Connect

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

    1982-01-01

    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.

  13. Fast numerical determination of symmetric sparsity patterns

    SciTech Connect

    Carter, R.G.

    1994-08-01

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

  14. Electroweak Baryogenesis in R-symmetric Supersymmetry

    SciTech Connect

    Fok, R.; Kribs, Graham D.; Martin, Adam; Tsai, Yuhsin

    2013-03-01

    We demonstrate that electroweak baryogenesis can occur in a supersymmetric model with an exact R-symmetry. The minimal R-symmetric supersymmetric model contains chiral superfields in the adjoint representation, giving Dirac gaugino masses, and an additional set of "R-partner" Higgs superfields, giving R-symmetric \\mu-terms. New superpotential couplings between the adjoints and the Higgs fields can simultaneously increase the strength of the electroweak phase transition and provide additional tree-level contributions to the lightest Higgs mass. Notably, no light stop is present in this framework, and in fact, we require both stops to be above a few TeV to provide sufficient radiative corrections to the lightest Higgs mass to bring it up to 125 GeV. Large CP-violating phases in the gaugino/higgsino sector allow us to match the baryon asymmetry of the Universe with no constraints from electric dipole moments due to R-symmetry. We briefly discuss some of the more interesting phenomenology, particularly of the of the lightest CP-odd scalar.

  15. KK molecules with momentum-dependent interactions

    SciTech Connect

    Lemmer, R. H.

    2009-10-15

    It is shown that the momentum-dependent kaon-antikaon interactions generated via vector-meson exchange from the standard SU{sub V}(3)xSU{sub A}(3) interaction Lagrangian lead to a nonlocal potential in coordinate space that can be incorporated without approximation into a nonrelativistic version of the Bethe-Salpeter wave equation containing a radial-dependent effective kaon mass appearing in a fully symmetrized kinetic energy operator, in addition to a local potential. Estimates of the mass and decay widths of f{sub 0}(980) and a{sub 0}(980), considered as KK molecules of isospin 0 and 1, as well as for K{sup +}K{sup -} atomic bound states (kaonium) are presented and compared with previous studies of a similar nature. It is argued that without a better knowledge of hadronic form factors it is not possible to distinguish between the molecular versus elementary particle models for the structure of the light scalar mesons.

  16. Creation of Functional Micro/Nano Systems through Top-down and Bottom-up Approaches

    PubMed Central

    Wong, Tak-Sing; Brough, Branden; Ho, Chih-Ming

    2009-01-01

    Mimicking nature’s approach in creating devices with similar functional complexity is one of the ultimate goals of scientists and engineers. The remarkable elegance of these naturally evolved structures originates from bottom-up self-assembly processes. The seamless integration of top-down fabrication and bottom-up synthesis is the challenge for achieving intricate artificial systems. In this paper, technologies necessary for guided bottom-up assembly such as molecular manipulation, molecular binding, and the self assembling of molecules will be reviewed. In addition, the current progress of synthesizing mechanical devices through top-down and bottom-up approaches will be discussed. PMID:19382535

  17. MHD Integrated Topping Cycle Project

    SciTech Connect

    Not Available

    1992-07-01

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

  18. Canada's top 5 in 5.

    PubMed

    Villeneuve, Michael; Wildfong, Don

    2013-01-01

    In 2011, the Canadian Nurses Association made a decision to establish and fund a national commission focused on health system transformation, the National Expert Commission. In 2012, the commission presented an action plan, the lead recommendation of which was to ensure that Canada ranks among the top five nations on five key population health status and system performance indicators in the next five years. In this article, the authors outline the selection of the these indicators and the associated goals for improvement. PMID:24034771

  19. Table-top job analysis

    SciTech Connect

    Not Available

    1994-12-01

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

  20. Symmetric and nonsymmetric vortices for the Ginzburg-Landau equations

    SciTech Connect

    Chen, Y.

    1985-01-01

    Steady-state Ginzburg-Landau equations with arbitrary parameter lambda > 0 in two-dimensional Euclidean space were studied. The existence of finite-energy symmetric and nonsymmetric solutions with arbitrary vortex number is demonstrated by direct method of the calculus of variations via a Sobolev space argument. Moreover, the important properties of symmetric solutions are determined, and it is proved that as lambda ..-->.. infinity, nonlinear desingularization occurs for the symmetric solutions.

  1. Nonlinear dynamic analysis of quasi-symmetric anisotropic structures

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Peters, Jeanne M.

    1987-01-01

    An efficient computational method for the nonlinear dynamic analysis of quasi-symmetric anisotropic structures is proposed. The application of mixed models simplifies the analytical development and improves the accuracy of the response predictions, and operator splitting allows the reduction of the analysis model of the quasi-symmetric structure to that of the corresponding symmetric structure. The preconditoned conjugate gradient provides a stable and effective technique for generating the unsymmetric response of the structure as the sum of a symmetrized response plus correction modes. The effectiveness of the strategy is demonstrated with the example of a laminated anisotropic shallow shell of quadrilateral planform subjected to uniform normal loading.

  2. Passive PT -symmetric couplers without complex optical potentials

    NASA Astrophysics Data System (ADS)

    Lee, Yi-Chan; Liu, Jibing; Chuang, You-Lin; Hsieh, Min-Hsiu; Lee, Ray-Kuang

    2015-11-01

    In addition to the implementation of parity-time-(PT -) symmetric optical systems by carefully and actively controlling the gain and loss, we show that a 2 ×2 PT -symmetric Hamiltonian has a unitarily equivalent representation without complex optical potentials in the resulting optical coupler. Through the Naimark dilation in operator algebra, passive PT -symmetric couplers can thus be implemented with a refractive index of real values and asymmetric coupling coefficients. This opens up the possibility to implement general PT -symmetric systems with state-of-the-art asymmetric slab waveguides, dissimilar optical fibers, or cavities with chiral mirrors.

  3. Passive $\\mathcal{PT}$-symmetric couplers without complex optical potentials

    E-print Network

    Lee, Yi-Chan; Chuang, You-Lin; Hsieh, Min-Hsiu; Lee, Ray-Kuang

    2015-01-01

    In addition to the implementation of parity-time ($\\mathcal{PT}$)-symmetric optical systems by carefully and actively controlling the gain and loss, we show that a $2\\times 2$ $\\mathcal{PT}$-symmetric Hamiltonian has a unitarily equivalent representation without complex optical potentials in the resulting optical coupler. Through the Naimark dilation in operator algebra, passive $\\mathcal{PT}$-symmetric couplers can thus be implemented with a refractive index of real values and asymmetric coupling coefficients. This opens up the possibility to implement general $\\mathcal{PT}$-symmetric systems with state-of-the-art asymmetric slab waveguides, dissimilar optical fibers, or cavities with chiral mirrors.

  4. Passive $\\mathcal{PT}$-symmetric couplers without complex optical potentials

    E-print Network

    Yi-Chan Lee; Jibing Liu; You-Lin Chuang; Min-Hsiu Hsieh; Ray-Kuang Lee

    2015-10-16

    In addition to the implementation of parity-time ($\\mathcal{PT}$)-symmetric optical systems by carefully and actively controlling the gain and loss, we show that a $2\\times 2$ $\\mathcal{PT}$-symmetric Hamiltonian has a unitarily equivalent representation without complex optical potentials in the resulting optical coupler. Through the Naimark dilation in operator algebra, passive $\\mathcal{PT}$-symmetric couplers can thus be implemented with a refractive index of real values and asymmetric coupling coefficients. This opens up the possibility to implement general $\\mathcal{PT}$-symmetric systems with state-of-the-art asymmetric slab waveguides, dissimilar optical fibers, or cavities with chiral mirrors.

  5. Entanglement equivalence of N-qubit symmetric states

    SciTech Connect

    Mathonet, P.; Krins, S.; Bastin, T.; Godefroid, M.; Solano, E.

    2010-05-15

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

  6. MHD Integrated Topping Cycle Project

    SciTech Connect

    Not Available

    1992-01-01

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

  7. MHD Integrated Topping Cycle Project

    SciTech Connect

    Not Available

    1992-03-01

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

  8. 1Modeling molecules 2Molecular . . .

    E-print Network

    Servatius, Brigitte

    ·Full Screen ·Close ·Quit 1. Modeling molecules (special graphs) - can we predict rigidity? Single atom ·Go Back ·Full Screen ·Close ·Quit Graph G of atoms and covalent bonds Body and hinge model Atoms1Modeling molecules 2Molecular . . . 3Realization in . . . Home Page Title Page Page 1 of 40 Go

  9. Proregenerative Properties of ECM Molecules

    PubMed Central

    Plantman, Stefan

    2013-01-01

    After traumatic injuries to the nervous system, regrowing axons encounter a complex microenvironment where mechanisms that promote regeneration compete with inhibitory processes. Sprouting and axonal regrowth are key components of functional recovery but are often counteracted by inhibitory molecules. This review covers extracellular matrix molecules that support neuron axonal outgrowth. PMID:24195084

  10. Micro-Kelvin cold molecules.

    SciTech Connect

    Strecker, Kevin E.; Chandler, David W.

    2009-10-01

    We have developed a novel experimental technique for direct production of cold molecules using a combination of techniques from atomic optical and molecular physics and physical chemistry. The ability to produce samples of cold molecules has application in a broad spectrum of technical fields high-resolution spectroscopy, remote sensing, quantum computing, materials simulation, and understanding fundamental chemical dynamics. Researchers around the world are currently exploring many techniques for producing samples of cold molecules, but to-date these attempts have offered only limited success achieving milli-Kelvin temperatures with low densities. This Laboratory Directed Research and Development project is to develops a new experimental technique for producing micro-Kelvin temperature molecules via collisions with laser cooled samples of trapped atoms. The technique relies on near mass degenerate collisions between the molecule of interest and a laser cooled (micro-Kelvin) atom. A subset of collisions will transfer all (nearly all) of the kinetic energy from the 'hot' molecule, cooling the molecule at the expense of heating the atom. Further collisions with the remaining laser cooled atoms will thermally equilibrate the molecules to the micro-Kelvin temperature of the laser-cooled atoms.

  11. Loosely-Bound Diatomic Molecules.

    ERIC Educational Resources Information Center

    Balfour, W. J.

    1979-01-01

    Discusses concept of covalent bonding as related to homonuclear diatomic molecules. Article draws attention to the existence of bound rare gas and alkaline earth diatomic molecules. Summarizes their molecular parameters and offers spectroscopic data. Strength and variation with distance of interatomic attractive forces is given. (Author/SA)

  12. Study of the rovibrational intensities of tetrahedral molecules and prediction of the pentad poliade of 12CD4

    NASA Astrophysics Data System (ADS)

    Kaarour, A.; Ouardi, O.; Meskine, M.

    2015-03-01

    The use of tensor models adapted to tetrahedral molecules such CH4, SiH4, GeH4... that use mathematical tools (group theory, irreducible tensor operators) and the characteristics of symmetrical molecules, gives good results. Starting from an experimental spectrum, we can calculate some parameters of the Hamiltonian and consequently the energy levels. Once the line positions are determined, we calculate the parameters of the dipole moment of these molecules and consequently the rovibrational intensities. Both software STDS and SPVIEW, we determined the parameters of the Hamiltonian and those of the dipole moment.

  13. Symmetric instability in the Gulf Stream

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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.

  14. Theory of molecule metal nano-particle interaction: Quantum description of plasmonic lasing

    NASA Astrophysics Data System (ADS)

    Zhang, Yuan; May, Volkhard

    2015-06-01

    The recent quantum description of a few molecules interacting with plasmon excitations of a spherical metal nano-particle (MNP) as presented in the work of Zhang and May [Phys. Rev. B 89, 245441 (2014)] is extended to systems with up to 100 molecules. We demonstrate the possibility of multiple plasmon excitation and describe their conversion into far-field photons. The calculation of the steady-state photon emission spectrum results in an emission line-narrowing with an increasing number of molecules coupled to the MNP. This is considered as an essential criterion for the action of the molecule-MNP system as a nano-laser. To have exact results for systems with up to 20 molecules, we proceed as recently described by Richter et al. [Phys. Rev. B 91, 035306 (2015)] and study a highly symmetric system. It assumes an equatorial and regular position of identical molecules in such a way that their coupling is dominated by that to a single MNP dipole-plasmon excitation. Changing from the exact computation of the system's complete density matrix to an approximate theory based on the reduced plasmon density matrix, systems with more than 100 molecules can be described. Finally, nonlinear rate equations are proposed which reproduce the mean number of excited plasmons in their dependence of the number of molecules and of the used pump rate. The second order intensity correlation function of emitted photons is related to the respective plasmon correlation function which approaches unity when the system starts lasing.

  15. Theory of molecule metal nano-particle interaction: Quantum description of plasmonic lasing.

    PubMed

    Zhang, Yuan; May, Volkhard

    2015-06-14

    The recent quantum description of a few molecules interacting with plasmon excitations of a spherical metal nano-particle (MNP) as presented in the work of Zhang and May [Phys. Rev. B 89, 245441 (2014)] is extended to systems with up to 100 molecules. We demonstrate the possibility of multiple plasmon excitation and describe their conversion into far-field photons. The calculation of the steady-state photon emission spectrum results in an emission line-narrowing with an increasing number of molecules coupled to the MNP. This is considered as an essential criterion for the action of the molecule-MNP system as a nano-laser. To have exact results for systems with up to 20 molecules, we proceed as recently described by Richter et al. [Phys. Rev. B 91, 035306 (2015)] and study a highly symmetric system. It assumes an equatorial and regular position of identical molecules in such a way that their coupling is dominated by that to a single MNP dipole-plasmon excitation. Changing from the exact computation of the system's complete density matrix to an approximate theory based on the reduced plasmon density matrix, systems with more than 100 molecules can be described. Finally, nonlinear rate equations are proposed which reproduce the mean number of excited plasmons in their dependence of the number of molecules and of the used pump rate. The second order intensity correlation function of emitted photons is related to the respective plasmon correlation function which approaches unity when the system starts lasing. PMID:26071722

  16. Spin squeezing, negative correlations, and concurrence in the quantum kicked top model.

    PubMed

    Wang, Xiaoqian; Ma, Jian; Song, Lijun; Zhang, Xihe; Wang, Xiaoguang

    2010-11-01

    We study spin squeezing, negative correlations, and concurrence in the quantum kicked top model. We prove that the spin squeezing and negative correlations are equivalent for spin systems with only symmetric Dicke states populated. We numerically analyze spin squeezing parameters and concurrence in this model and find that the maximal spin squeezing direction, which refers to the minimal pairwise correlation direction, is strongly influenced by quantum chaos. Entanglement (spin squeezing) sudden death and sudden birth occur alternatively for the periodic and quasiperiodic cases, while only entanglement (spin squeezing) sudden death is found for the chaotic case. PMID:21230561

  17. Can entanglement efficiently be weakend by symmetrization?

    E-print Network

    Keiji Matsumoto

    2005-12-09

    Consider a quantum system with $m$ subsystems with $n$ qubits each, and suppose the state of the system is living in the symmetric subspace. It is known that, in the limit of $m\\to\\infty$, entanglement between any two subsystems vanishes. In this paper we study asymptotic behavior of the entanglement as $m$ and $n$ grows. Our conjecture is that if $m$ is a polynomially bounded function in $n$, then the entanglement decreases polynomially. The motivation of this study is a study of quantum Merlin-Arthur game. If this conjecture is ture, we can prove that bipartite separable certificate does not increase the computational power of the proof system. protocol. In the paper, we provide two evidences which support the conjecture. First, if $m$ is an exponential function, then entanglement decreases exponentially fast. Second, in case of a maximally entangled state, our conjecture is true.

  18. Powers of Symmetric Differential Operators I

    E-print Network

    Bruce K. Driver; Pun Wai Tong

    2015-10-30

    Let $L$ be a linear symmetric differential operators on $L^{2}\\left( \\mathbb{R}\\right) $ whose domain is the Schwartz test function space, $\\mathcal{S}.$ For the majority of this paper, it is assumed that the coefficient of $L$ are polynomial functions on $\\mathbb{R}.$ We will give criteria on the polynomial coefficients of $L$ which guarantees that $L$ is essentially self-adjoint, $\\bar{L}\\geq-CI$ for some $C0,$ in the coefficients is used to provide a large class of operators satisfying the hypotheses in our another paper "On the classical limit of quantum mechanics" (will be submitted very soon) where a strong form of the classical limit of quantum mechanics is shown to hold.

  19. Cracked shells under skew-symmetric loading

    NASA Technical Reports Server (NTRS)

    Lelale, F.

    1982-01-01

    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 strains, all boundary conditions on the crack surfaces are satisfied separately. Consequently, unlike those obtained from the classical shell theory, the angular distributions of the stress components around the crack tips are shown to be identical to the distributions obtained from the plane and antiplane elasticity solutions. Extensive results are given for axially and circumferentially cracked cylindrical shells, spherical shells, and toroidal shells under uniform inplane shearing, out of plane shearing, and torsion. The effect of orthotropy on the results is also studied.

  20. Acoustic horizons in axially symmetric relativistic accretion

    E-print Network

    Hrvoje Abraham; Neven Bilic; Tapas K. Das

    2006-04-26

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

  1. Minimal Left-Right Symmetric Dark Matter.

    PubMed

    Heeck, Julian; Patra, Sudhanwa

    2015-09-18

    We show that left-right symmetric models can easily accommodate stable TeV-scale dark matter particles without the need for an ad hoc stabilizing symmetry. The stability of a newly introduced multiplet either arises accidentally as in the minimal dark matter framework or comes courtesy of the remaining unbroken Z_{2} subgroup of B-L. Only one new parameter is introduced: the mass of the new multiplet. As minimal examples, we study left-right fermion triplets and quintuplets and show that they can form viable two-component dark matter. This approach is, in particular, valid for SU(2)×SU(2)×U(1) models that explain the recent diboson excess at ATLAS in terms of a new charged gauge boson of mass 2 TeV. PMID:26430988

  2. Diagonal Markowitz scheme with local symmetrization

    SciTech Connect

    Amestoy, Patrick R.; Li, Xiaoye S.; Eg, Esmond G.

    2003-12-10

    It is well known that sparse matrix factorizations sufferfill. That is, there are often more nonzero entries in the triangularfactors than in the original matrix. One of the factors that affect thesparsity of the factorization is the sparsity structure of the originalmatrix, which can be changed by permuting the rows and columns of thematrix. In this paper we are concerned with the case when the matrix isnonsymmetric. In particular, we are interested in ordering algorithmsthat do not depend on the numerical values so that they can be computedusing structural information alone. Most such ordering algorithms arebased on some sort of symmetrization of the original matrix. We describein this paper an ordering algorithm that uses the nonsymmetric structureof the given matrix as much as possible. We will show that our algorithmcan be implemented in space bounded by the number of nonzero entries inthe original matrix. We will also provide numerical experimentsdemonstrating the quality of the orderings.

  3. VACUUM calculation in azimuthally symmetric geometry

    SciTech Connect

    Chance, M.S.

    1996-11-01

    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.

  4. Geometric inequalities for axially symmetric black holes

    E-print Network

    Sergio Dain

    2012-03-01

    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 closed 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 problem is presented.

  5. Pseudo-Z symmetric space-times

    SciTech Connect

    Mantica, Carlo Alberto; Suh, Young Jin

    2014-04-15

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

  6. Invisibility in PT-symmetric complex crystals

    E-print Network

    Stefano Longhi

    2011-11-15

    Bragg scattering in sinusoidal PT-symmetric complex crystals of finite thickness is theoretically investigated by the derivation of exact analytical expressions for reflection and transmission coefficients in terms of modified Bessel functions of first kind. The analytical results indicate that unidirectional invisibility, recently predicted for such crystals by coupled-mode theory [Z. Lin et al., Phys. Rev. Lett. 106, 213901 (2011)], breaks down for crystals containing a large number of unit cells. In particular, for a given modulation depth in a shallow sinusoidal potential, three regimes are encountered as the crystal thickness is increased. At short lengths the crystal is reflectionless and invisible when probed from one side (unidirectional invisibility), whereas at intermediate lengths the crystal remains reflectionless but not invisible; for longer crystals both unidirectional reflectionless and invisibility properties are broken.

  7. Cosmic ray antimatter and baryon symmetric cosmology

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Protheroe, R. J.; Kazanas, D.

    1982-01-01

    The relative merits and difficulties of the primary and secondary origin hypotheses for the observed cosmic-ray antiprotons, including the new low-energy measurement of Buffington, et al. We conclude that the cosmic-ray antiproton data may be evidence for antimatter galaxies and baryon symmetric cosmology. The present bar P data are consistent with a primary extragalactic component having /p=/equiv 1+/- 3.2/0.7x10 = to the -4 independent of energy. We propose that the primary extragalactic cosmic ray antiprotons are most likely from active galaxies and that expected disintegration of bar alpha/alpha ban alpha/alpha. We further predict a value for ban alpha/alpha =/equiv 10 to the -5, within range of future cosmic ray detectors.

  8. Cylindrically Symmetric Models of Anisotropic Compact Stars

    E-print Network

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

    2014-12-16

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

    High resolution OLED-on-silicon microdisplay technology is unique and challenging since it requires very small subpixel dimensions (~ 2-5 microns). eMagin's OLED microdisplay is based on white top emitter architecture using small molecule organic materials. The devices are fabricated using high Tg materials. The devices are hermetically sealed with vacuum deposited thin film layers. LCD-type color filters are patterned using photolithography methods to generate primary R, G, B colors. Results of recent improvements in the OLED-on-silicon microdisplay technology, with emphasis on efficiencies, lifetimes, grey scale and CIE color coordinates for SVGA and SXGA resolution microdisplays is presented.

  10. Duality symmetric string and M-theory

    NASA Astrophysics Data System (ADS)

    Berman, David S.; Thompson, Daniel C.

    2015-03-01

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

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

    PubMed Central

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

    2013-01-01

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

  12. Top-down Proteomics in Health and Disease: Challenges and Opportunities

    PubMed Central

    Gregorich, Zachery R.; Ge, Ying

    2014-01-01

    Proteomics is essential for deciphering how molecules interact as a system and for understanding the functions of cellular systems in human disease; however, the unique characteristics of the human proteome, which include a high dynamic range of protein expression and extreme complexity due to a plethora of post-translational modifications (PTMs) and sequence variations, make such analyses challenging. An emerging “top-down” mass spectrometry (MS)-based proteomics approach, which provides a “bird’s eye” view of all proteoforms, has unique advantages for the assessment of PTMs and sequence variations. Recently, a number of studies have showcased the potential of top-down proteomics for unraveling of disease mechanisms and discovery of new biomarkers. Nevertheless, the top-down approach still faces significant challenges in terms of protein solubility, separation, and the detection of large intact proteins, as well as the under-developed data analysis tools. Consequently, new technological developments are urgently needed to advance the field of top-down proteomics. Herein, we intend to provide an overview of the recent applications of top-down proteomics in biomedical research. Moreover, we will outline the challenges and opportunities facing top-down proteomics strategies aimed at understanding and diagnosing human diseases. PMID:24723472

  13. Review on top forward-backward asymmetry

    E-print Network

    P. Ko

    2013-01-08

    The top forward-backward asymmetry (FBA) observed at the Tevatron has been a hot issue in particle physics for the last few years. In this talk, I describe two different approaches for the top FBA at the Tevatron, one in effective field theory (EFT) approach and the other in explicit model for $Z'$. Within the first approach, I identify a class of models which can accommodate the top FBA when new physics scale is very heavy. Axigluon or $t$-channel scalar exchanges with flavor dependent couplings can do the job. In the second approach, I show that the chiral couplings of $Z'$ necessarily invites multi Higgs doublets with $Z'$ couplings. Otherwise the top quark becomes massless, which is completely unphysical. Newly introduced multi Higgs doublets also contribute to the top FBA, $\\sigma_{tt}$ and the charge asymmetry at the LHC, and there are parameter regions which are compatible with all the observations related with the top quarks.

  14. Constraints From $b \\to s?$ on the Left-Right Symmetric Model

    E-print Network

    Thomas G. Rizzo

    1994-01-25

    Recent results from the CLEO Collaboration on both inclusive and exclusive radiative $B$ decays are used to constrain the parameter space of two versions of the Left-Right Symmetric Model. In the first scenario, when the left- and right-handed Cabibbo-Kobayashi-Maskawa mixing matrices are equal, $V_L=V_R$, the radiative $B$ decay data is shown to lead to strong bounds on the $W_L-W_R$ mixing angle that are quite insensitive to either the top quark or $W_R$ mass. The second scenario examined is that of Gronau and Wakaizumi wherein $b$-quark decays proceed only via right-handed currents and $V_L$ and $V_R$ are quite distinct. For this model, the combined constraints from Tevatron $W_R$ searches, the $B$ lifetime, and radiative $B$ decays lead to a very highly restricted allowed range for the $W_L-W_R$ mixing angle.

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

    SciTech Connect

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

    2009-10-16

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

  16. Photon polarization in the b ? s? processes in the left-right symmetric model

    NASA Astrophysics Data System (ADS)

    Yu, Fu-Sheng; Kou, Emi; Lü, Cai-Dian

    2013-12-01

    The circular-polarization of the photon in the radiative B decays is dominantly left-handed in the Standard Model (SM), but the right-handed polarization may be enhanced in some new physics models with right-handed currents, such as the Left-Right Symmetric Model (LRSM). In this article, we investigate how large this wrong polarization could be within the allowed parameter space of the LRSM. We show that in the LRSM, the right-handed polarization of the photon in the b ? s? processes could be largely enhanced by the W L - W R mixing contributions because of the helicity flip on the internal top quark line of the penguin diagrams and the enhancement by the CKM factor . We discuss the sensitivity of the proposed methods to determine the b ? s? photon polarization to the LRSM as well as their complementary role compared to the direct search of right-handed charged gauge bosons at LHC.

  17. Top quark physics at the Tevatron

    SciTech Connect

    D. Gerdes

    2004-01-28

    Precision studies of the top quark are a prime goal of the Run II physics program at the Fermilab Tevatron. Since the start of Run II in early 2002, the CDF and D0 experiments have analyzed approximately 100 pb{sup -1} of data and have re-established the top quark signal. In this article the author summarizes recent measurements of the top production cross section and mass.

  18. Top quark mass: past, present and future

    SciTech Connect

    Gutierrez, Gaston; /Fermilab

    2007-07-01

    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 W boson mass, plays an important role in constraining the Higgs boson mass. The current status of the top quark mass measurement and a brief outline of the expectation at the Large Hadron Collider and the International Linear Collider will be covered.

  19. TOP500 Supercomputers for November 2004

    SciTech Connect

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

    2004-11-08

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

  20. TOP500 Supercomputers for June 2004

    SciTech Connect

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

    2004-06-23

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

  1. TOP500 Supercomputers for June 2005

    SciTech Connect

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

    2005-06-22

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

  2. Single Molecule Electronics and Devices

    PubMed Central

    Tsutsui, Makusu; Taniguchi, Masateru

    2012-01-01

    The manufacture of integrated circuits with single-molecule building blocks is a goal of molecular electronics. While research in the past has been limited to bulk experiments on self-assembled monolayers, advances in technology have now enabled us to fabricate single-molecule junctions. This has led to significant progress in understanding electron transport in molecular systems at the single-molecule level and the concomitant emergence of new device concepts. Here, we review recent developments in this field. We summarize the methods currently used to form metal-molecule-metal structures and some single-molecule techniques essential for characterizing molecular junctions such as inelastic electron tunnelling spectroscopy. We then highlight several important achievements, including demonstration of single-molecule diodes, transistors, and switches that make use of electrical, photo, and mechanical stimulation to control the electron transport. We also discuss intriguing issues to be addressed further in the future such as heat and thermoelectric transport in an individual molecule. PMID:22969345

  3. Quantum Magnetism with Ultracold Molecules

    NASA Astrophysics Data System (ADS)

    Wall, M. L.; Hazzard, K. R. A.; Rey, A. M.

    2015-06-01

    This article gives an introduction to the realization of effective quantum magnetism with ultracold molecules in an optical lattice, reviews experimental and theoretical progress, and highlights future opportunities opened up by ongoing experiments. Ultracold molecules offer capabilities that are otherwise difficult or impossible to achieve in other effective spin systems, such as long-ranged spin-spin interactions with controllable spatial and spin anisotropy and favorable energy scales. Realizing quantum magnetism with ultracold molecules provides access to rich many-body behaviors, including many exotic phases of matter and interesting excitations and dynamics. Far-from-equilibrium dynamics plays a key role in our exposition, just as it did in recent ultracold molecule experiments realizing effective quantum magnetism. In particular, we show that dynamical probes allow the observation of correlated many-body spin physics, even in polar molecule gases that are not quantum degenerate. After describing how quantum magnetism arises in ultracold molecules and discussing recent observations of quantum magnetism with polar molecules, we survey prospects for the future, ranging from immediate goals to long-term visions.

  4. MHD Integrated Topping Cycle Project

    SciTech Connect

    Not Available

    1992-07-01

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

  5. Top-Down and Free

    NASA Astrophysics Data System (ADS)

    Schillaci, Michael

    2007-11-01

    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.

  6. Controlling molecules with lasers and lasers with molecules

    E-print Network

    Taylor, Jason Matthew, 1977-

    2007-01-01

    I investigate quantum control of spin in molecules using shaped ultrafast lasers and the dynamics of those lasers when their cavities are modified to include programmable molecular masks. The ability to control quantum ...

  7. Observations of severe turbulence near thunderstorm tops

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  8. Top quark physics in hadron collisions

    E-print Network

    Wolfgang Wagner

    2007-08-03

    The top quark is the heaviest elementary particle observed to date. Its large mass makes the top quark an ideal laboratory to test predictions of perturbation theory concerning heavy quark production at hadron colliders. The top quark is also a powerful probe for new phenomena beyond the Standard Model of particle physics. In addition, the top quark mass is a crucial parameter for scrutinizing the Standard Model in electroweak precision tests and for predicting the mass of the yet unobserved Higgs boson. Ten years after the discovery of the top quark at the Fermilab Tevatron top quark physics has entered an era where detailed measurements of top quark properties are undertaken. In this review article an introduction to the phenomenology of top quark production in hadron collisions is given, the lessons learned in Tevatron Run I are summarized, and first Run II results are discussed. A brief outlook to the possibilities of top quark research a the Large Hadron Collider, currently under construction at CERN, is included.

  9. Top Quark Production Asymmetries AFBt and AFBl

    DOE PAGESBeta

    Berger, Edmond L.; Cao, Qing-Hong; Chen, Chuan-Ren; Yu, Jiang-Hao; Zhang, Hao

    2012-02-14

    A large forward-backward asymmetry is seen in both the top quark rapidity distribution AFBt and in the rapidity distribution of charged leptons AFBl from top quarks produced at the Tevatron. We study the kinematic and dynamic aspects of the relationship of the two observables arising from the spin correlation between the charged lepton and the top quark with different polarization states. We emphasize the value of both measurements, and we conclude that a new physics model which produces more right-handed than left-handed top quarks is favored by the present data.

  10. Beyond the minimal top partner decay

    NASA Astrophysics Data System (ADS)

    Serra, Javi

    2015-09-01

    Light top partners are the prime sign of naturalness in composite Higgs models. We explore here the possibility of non-standard top partner phenomenology. We show that even in the simplest extension of the minimal composite Higgs model, featuring an extra singlet pseudo Nambu-Goldstone boson, the branching ratios of the top partners into standard channels can be significantly altered, with no substantial change in the generated Higgs potential. Together with the variety of possible final states from the decay of the pseudo-scalar singlet, this motivates more extensive analyses in the search for the top partners.

  11. ON THE BLOCK TRIANGULAR FORM OF SYMMETRIC MATRICES

    E-print Network

    Uçar, Bora

    ON THE BLOCK TRIANGULAR FORM OF SYMMETRIC MATRICES IAIN S. DUFF AND BORA UC¸AR§ Abstract. We present some observations on the block triangular form (btf) of structurally symmetric, square, sparse and one overdetermined block. We prove that these blocks are transposes of each other. We further prove

  12. Onesided Block Jacobi Methods for the Symmetric Eigenvalue Problem ?

    E-print Network

    Giménez, Domingo

    One­sided Block Jacobi Methods for the Symmetric Eigenvalue Problem ? D. Gim'enez 1 , J. Cuenca 1 theoretically two different one­sided block Jacobi algorithms for solving the Symmetric Eigenvalue Problem. Sequential and parallel versions of the algorithms are analized and com­ pared with a two­sided block Jacobi

  13. Four Interesting Types of Symmetric Two-Player Games

    E-print Network

    Tesfatsion, Leigh

    Four Interesting Types of Symmetric Two-Player Games Leigh Tesfatsion Department of Economics Iowa-Player Game Player 2 C D C (R, R) (S, T) Player 1 D (T, S) (P, P) Action choices for each player: C or D Possible payoffs for each player: R, S, T, or P #12;Game Analysis The analysis of symmetric two

  14. RECIPROCITY ALGEBRAS AND BRANCHING FOR CLASSICAL SYMMETRIC PAIRS

    E-print Network

    Stephan, Frank

    , AND JEB F. WILLENBRING Abstract. We study branching laws for a classical group G and a symmetric sub- group H. Our approach is through the branching algebra, the algebra of covariants for H in the regular out that the ten classes of classical symmetric pairs (G, H) are associated in pairs, (G, H) and (H

  15. RECIPROCITY ALGEBRAS AND BRANCHING FOR CLASSICAL SYMMETRIC PAIRS

    E-print Network

    Willenbring, Jeb F.

    , AND JEB F. WILLENBRING Abstract. We study branching laws for a classical group G and a symmetric subgroup H. Our approach is by introducing the branching algebra, the algebra of covariants for H out that the ten classes of classical symmetric pairs (G, H) are associated in pairs, (G, H) and (H

  16. Polynomial Reproduction by Symmetric Subdivision Schemes School of Mathematical Sciences

    E-print Network

    Hormann, Kai

    Polynomial Reproduction by Symmetric Subdivision Schemes Nira Dyn School of Mathematical Sciences, uniform, and stationary sub- division scheme to have polynomial reproduction of degree d and thus of polynomial reproduction for two families of symmetric schemes, the family of pseudo-splines and a new family

  17. Symmetric Characterization of Finite State Markov Mohammad Rezaeian

    E-print Network

    Rezaeian, Mohammad-Jafar

    Symmetric Characterization of Finite State Markov Channels Mohammad Rezaeian Department state Markov chan- nels. We show that for symmetric Markov channels the noise process can, and for these cases direct formulae for computation of capacity exist. For finite state Markov channels [3

  18. SOUNDNESS AND COMPLETENESS OF FORMAL LOGICS OF SYMMETRIC Gergei Bana

    E-print Network

    International Association for Cryptologic Research (IACR)

    SOUNDNESS AND COMPLETENESS OF FORMAL LOGICS OF SYMMETRIC ENCRYPTION Gergei Bana A DISSERTATION Harbater, Graduate Group Chairperson #12;COPYRIGHT Gergei Bana 2005 #12;Acknowledgements I would like;ABSTRACT SOUNDNESS AND COMPLETENESS OF FORMAL LOGICS OF SYMMETRIC ENCRYPTION Gergei Bana Supervisor: Andre

  19. Bilateral Symmetrical Congenital Giant Becker's Nevus: A Rare Presentation

    PubMed Central

    Rao, Angoori Gnaneshwar

    2015-01-01

    Becker's nevus is a focal epidermal hypermelanotic disorder. It morphologically presents as unilateral, hyperpigmented, hypertrichotic patch on upper trunk, proximal upper extremities and arms. However, Becker's nevus presenting as bilateral, symmetrical patches is rare. Herein, we report a rare case of giant Becker's nevus with bilateral symmetrical presentation in an adult male. PMID:26538733

  20. Symmetrical waveform generation based on temporal pulse shaping using

    E-print Network

    Yao, Jianping

    Symmetrical waveform generation based on temporal pulse shaping using amplitude-only modulator H. Chi and J. Yao Symmetrical waveform generation based on temporal pulse shaping using only an amplitude: Spatial light modulator (SLM)-based sub-picosecond pulse shaping for arbitrary waveform generation, which

  1. THE INFINITE SYMMETRIC PRODUCT AND HOMOLOGY ANDREW VILLADSEN

    E-print Network

    May, J. Peter

    THE INFINITE SYMMETRIC PRODUCT AND HOMOLOGY THEORY ANDREW VILLADSEN Abstract. Following the work. The infinite symmetric product allows the construction of a reduced homology theory on CW com- plexes in terms generated Abelian groups of CW complexes which are Moore spaces. Contents 1. Introduction 1 2. The infinite

  2. A symmetric surface micromachined gyroscope with decoupled oscillation modes

    E-print Network

    Akin, Tayfun

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

  3. SYMMETRIC UNIONS WITHOUT COSMETIC CROSSING CHANGES ALLISON H. MOORE

    E-print Network

    Harvey, Shelly

    SYMMETRIC UNIONS WITHOUT COSMETIC CROSSING CHANGES ALLISON H. MOORE Abstract. A symmetric union-known cosmetic crossing conjecture. This conjecture asserts that the only crossing changes which preserve the cosmetic crossing conjecture. An embedded disk D in S3 intersecting K twice with zero algebraic

  4. The hit problem for symmetric polynomials over the Steenrod algebra

    E-print Network

    Wood, Reginald M W

    The hit problem for symmetric polynomials over the Steenrod algebra A. S. Janfada and R. M. W. Wood January 2001 Dedicated to the memory of Frank Peterson We cite [18] for references to work on the hit investigates the hit problem for the A-submodule of symmetric polynomials B(n) = P(n) #6;n , where #6; n

  5. Relative Sizes of Organic Molecules

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This computer graphic depicts the relative complexity of crystallizing large proteins in order to study their structures through x-ray crystallography. Insulin is a vital protein whose structure has several subtle points that scientists are still trying to determine. Large molecules such as insuline are complex with structures that are comparatively difficult to understand. For comparison, a sugar molecule (which many people have grown as hard crystals in science glass) and a water molecule are shown. These images were produced with the Macmolecule program. Photo credit: NASA/Marshall Space Flight Center (MSFC)

  6. Quantum transport through aromatic molecules

    SciTech Connect

    Ojeda, J. H.; Rey-González, R. R.; Laroze, D.

    2013-12-07

    In this paper, we study the electronic transport properties through aromatic molecules connected to two semi-infinite leads. The molecules are in different geometrical configurations including arrays. Using a nearest neighbor tight-binding approach, the transport properties are analyzed into a Green's function technique within a real-space renormalization scheme. We calculate the transmission probability and the Current-Voltage characteristics as a function of a molecule-leads coupling parameter. Our results show different transport regimes for these systems, exhibiting metal-semiconductor-insulator transitions and the possibility to employ them in molecular devices.

  7. Molecular Rotation Signals: Molecule Chemistry and Particle Physics

    NASA Astrophysics Data System (ADS)

    Grabow, Jens-Uwe

    2015-06-01

    Molecules - large or small - are attractive academic resources, with numerous questions on their chemical behaviour as well as problems in fundamental physics now (or still) waiting to be answered: Targeted by high-resolution spectroscopy, a rotating molecular top can turn into a laboratory for molecule chemistry or a laboratory for particle physics. Once successfully entrained (many species - depending on size and chemical composition - have insufficient vapour pressures or are of transient nature, such that specifically designed pulsed-jet sources are required for their transfer into the gas phase or in-situ generation) into the collision-free environment of a supersonic-jet expansion, each molecular top comes with its own set of challenges, theoretically and experimentally: Multiple internal interactions are causing complicated energy level schemes and the resulting spectra will be rather difficult to predict theoretically. Experimentally, these spectra are difficult to assess and assign. With today's broad-banded chirp microwave techniques, finding and identifying such spectral features have lost their major drawback of being very time consuming for many molecules. For other molecules, the unrivalled resolution and sensitivity of the narrow-banded impulse microwave techniques provide a window to tackle - at the highest precision available to date - fundamental questions in physics, even particle physics - potentially beyond the standard model. Molecular charge distribution, properties of the chemical bond, details on internal dynamics and intermolecular interaction, the (stereo-chemical) molecular structure (including the possibility of their spatial separation) as well as potential evidence for tiny yet significant interactions encode their signature in pure molecular rotation subjected to time-domain microwave spectroscopic techniques. Ongoing exciting technical developments promise rapid progress. We present recent examples from Hannover, new directions, and an outlook at the future of molecular rotation spectroscopy.

  8. Liquid-liquid interfacial properties of a symmetrical Lennard-Jones binary mixture.

    PubMed

    Martínez-Ruiz, F J; Moreno-Ventas Bravo, A I; Blas, F J

    2015-09-14

    We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, ?11 = ?22, with the same dispersive energy between like species, ?11 = ?22, but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janec?ek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances rc and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance rc is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related with a desorption of the molecules at the interface, a direct consequence of a combination of the weak dispersive interactions between unlike species of the symmetrical binary mixture, and the presence of an interfacial region separating the two immiscible liquid phases in coexistence. PMID:26374055

  9. Liquid-liquid interfacial properties of a symmetrical Lennard-Jones binary mixture

    NASA Astrophysics Data System (ADS)

    Martínez-Ruiz, F. J.; Moreno-Ventas Bravo, A. I.; Blas, F. J.

    2015-09-01

    We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, ?11 = ?22, with the same dispersive energy between like species, ?11 = ?22, but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janec?ek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances rc and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance rc is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related with a desorption of the molecules at the interface, a direct consequence of a combination of the weak dispersive interactions between unlike species of the symmetrical binary mixture, and the presence of an interfacial region separating the two immiscible liquid phases in coexistence.

  10. On Stationary Axially Symmetric Solutions in Brans-Dicke Theory

    E-print Network

    Kirezli, P?nar

    2015-01-01

    Stationary axially symmetric Brans-Dicke-Maxwell solutions are re-examined in the framework of the Brans-Dicke theory. We see that, employing a particular parametrization of the standard axially symmetric metric simplifies the procedure of obtaining the Ernst equations for axially symmetric electro-vacuum space-times for this theory. This analysis also permit us to construct a two parameter extension in both Jordan and Einstein frames of an old solution generating technique frequently used to construct axially symmetric solutions for Brans-Dicke theory from a seed solution of General Relativity. As applications of this technique, several known and new solutions are constructed including a general axially symmetric BD-Maxwell solution of Plebanski-Demianski with vanishing cosmological constant, i.e. the Kinnersley solution and general magnetized Kerr-Newman type solutions. Some physical properties and circular motion of test particles for a particular subclass of Kinnersley solution, i.e. Kerr-Newman-NUT type ...

  11. Geometric Entanglement of Symmetric States and the Majorana Representation

    NASA Astrophysics Data System (ADS)

    Aulbach, Martin; Markham, Damian; Murao, Mio

    Permutation-symmetric quantum states appear in a variety of physical situations, and they have been proposed for quantum information tasks. This article builds upon the results of [New J. Phys. 12 (2010) 073025], where the maximally entangled symmetric states of up to twelve qubits were explored, and their amount of geometric entanglement determined by numeric and analytic means. For this the Majorana representation, a generalization of the Bloch sphere representation, can be employed to represent symmetric n qubit states by n points on the surface of a unit sphere. Symmetries of this point distribution simplify the determination of the entanglement, and enable the study of quantum states in novel ways. Here it is shown that the duality relationship of Platonic solids has a counterpart in the Majorana representation, and that in general maximally entangled symmetric states neither correspond to anticoherent spin states nor to spherical designs. The usability of symmetric states as resources for measurement-based quantum computing is also discussed.

  12. Color symmetrical superconductivity in a schematic nuclear quark model

    E-print Network

    Henrik Bohr; João da Providência

    2009-10-13

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

  13. Bicriterion seriation methods for skew-symmetric matrices.

    PubMed

    Brusco, Michael J; Stahl, Stephanie

    2005-11-01

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

  14. Self-assembly of active colloidal molecules with dynamic function.

    PubMed

    Soto, Rodrigo; Golestanian, Ramin

    2015-05-01

    Catalytically active colloids maintain nonequilibrium conditions in which they produce and deplete chemicals and hence effectively act as sources and sinks of molecules. While individual colloids that are symmetrically coated do not exhibit any form of dynamical activity, the concentration fields resulting from their chemical activity decay as 1/r and produce gradients that attract or repel other colloids depending on their surface chemistry and ambient variables. This results in a nonequilibrium analog of ionic systems, but with the remarkable novel feature of action-reaction symmetry breaking. We study solutions of such chemically active colloids in dilute conditions when they join up to form molecules via generalized ionic bonds and discuss how we can achieve structures with time-dependent functionality. In particular, we study a molecule that adopts a spontaneous oscillatory pattern of conformations and another that exhibits a run-and-tumble dynamics similar to bacteria. Our study shows that catalytically active colloids could be used for designing self-assembled structures that possess dynamical functionalities that are determined by their prescribed three-dimensional structures, a strategy that follows the design principle of proteins. PMID:26066174

  15. Calculated line broadening parameters for methane perturbed by diatomic molecules

    NASA Astrophysics Data System (ADS)

    Gabard, Tony

    2013-09-01

    We report semiclassical line broadening calculations for methane perturbed by diatomic molecules: nitrogen, N2, oxygen, O2 and hydrogen, H2, at room temperature. For this, we have developed a symmetrized version of the Robert and Bonamy theory. The interaction potential was built from electrostatic (octopole and hexadecapole for methane, quadrupole for the diatomic molecules) and atom-atom contributions. The relative (classical) trajectories of the molecules were computed in the frame of the usual parabolic model, through analytical formula. High orders of developments had to be used for the short range molecular interactions in the case of N2 and O2. For H2, a lower order of development was found to be convenient. We have compared our calculations to some of the available experimental data for hydrogen and oxygen. For nitrogen, we have already reported some comparisons to measurements [T. Gabard, V. Boudon, J. Quant. Spectrosc. Radiat. Transfer 111 (2010) 1328-1343]. Thus, we report here new extensive calculations for the dyad (near 1300 cm-1) and the pentad (near 3000 cm-1) spectral regions.

  16. Self-assembly of Active Colloidal Molecules with Dynamic Function

    E-print Network

    Rodrigo Soto; Ramin Golestanian

    2015-02-25

    Catalytically active colloids maintain non-equilibrium conditions in which they produce and deplete chemicals and hence effectively act as sources and sinks of molecules. While individual colloids that are symmetrically coated do not exhibit any form of dynamical activity, the concentration fields resulting from their chemical activity decay as $1/r$ and produce gradients that attract or repel other colloids depending on their surface chemistry and ambient variables. This results in a non-equilibrium analogue of ionic systems, but with the remarkable novel feature of action-reaction symmetry breaking. We study solutions of such chemically active colloids in dilute conditions when they join up to form molecules via generalized ionic bonds, and discuss how we can achieve structures with time dependent functionality. In particular, we study a molecule that adopts a spontaneous oscillatory pattern of conformations, and another that exhibits a run-and-tumble dynamics similar to bacteria. Our study shows that catalytically active colloids could be used for designing self-assembled structures that posses dynamical functionalities that are determined by their prescribed 3D structures, a strategy that follows the design principle of proteins.

  17. Lipometer subcutaneous adipose tissue topography (SAT-Top) reflects serum leptin levels varying in circadian rhythms

    NASA Astrophysics Data System (ADS)

    Moeller, Reinhard; Tafeit, Erwin; Sudi, Karl; Vrecko, Karoline; Horejsi, Renate; Hinghofer-Szalkay, Helmut G.; Reibnegger, Gilbert

    1998-05-01

    Recent advances in obesity research have shown that the product of the ob-gene named leptin is related to total body fast mass in humans. There is, however, a debate if leptin levels are pulsatile and linked to body fat distribution. In this study we therefore investigated the subcutaneous adipose tissue topography (SAT-Top) measured by means of the newly developed device Lipometer and leptin levels during a 24 hours beginning at 0715am ending the same time in the next day. Blood samples for measurement of leptin were taken every 3 hours in a male subject. Measurements of SAT-Top were performed at 15 body sites from neck to calf at the left and right body site at the same time interval. We observed an almost symmetrically reaction of the left and right body site with a maximum of the mean value of all body sites in the evening at 0715pm. There was a negative correlation between serum leptin levels and SAT-Top using the set of certain body sites (R2 equals 0.80, p equals 0.01). If these combination of body sites is inversed and set against serum leptin levels, both curves show almost identical shape and time dependence. We conclude that SAT-Top by means of Lipometer is changed in a short time and related to leptin levels in the investigated male subject.

  18. A highly processive topoisomerase I: studies at the single-molecule level

    PubMed Central

    Szafran, Marcin Jan; Strick, Terence; Strza?ka, Agnieszka; Zakrzewska-Czerwi?ska, Jolanta; Jakimowicz, Dagmara

    2014-01-01

    Amongst enzymes which relieve torsional strain and maintain chromosome supercoiling, type IA topoisomerases share a strand-passage mechanism that involves transient nicking and re-joining of a single deoxyribonucleic acid (DNA) strand. In contrast to many bacterial species that possess two type IA topoisomerases (TopA and TopB), Actinobacteria possess only TopA, and unlike its homologues this topoisomerase has a unique C-terminal domain that lacks the Zn-finger motifs characteristic of type IA enzymes. To better understand how this unique C-terminal domain affects the enzyme's activity, we have examined DNA relaxation by actinobacterial TopA from Streptomyces coelicolor (ScTopA) using real-time single-molecule experiments. These studies reveal extremely high processivity of ScTopA not described previously for any other topoisomerase of type I. Moreover, we also demonstrate that enzyme processivity varies in a torque-dependent manner. Based on the analysis of the C-terminally truncated ScTopA mutants, we propose that high processivity of the enzyme is associated with the presence of a stretch of positively charged amino acids in its C-terminal region. PMID:24880688

  19. Fluorescence Microscopy of Single Molecules

    ERIC Educational Resources Information Center

    Zimmermann, Jan; van Dorp, Arthur; Renn, Alois

    2004-01-01

    The investigation of photochemistry and photophysics of individual quantum systems is described with the help of a wide-field fluorescence microscopy approach. The fluorescence single molecules are observed in real time.

  20. Moving Molecules and Mothball Madness.

    ERIC Educational Resources Information Center

    Strain, John

    1993-01-01

    Describes concrete demonstrations on the states of matter. In the first demonstration, students represent molecules; and, in the second demonstration, moth balls are heated to produce a change of state. (PR)

  1. Molecular biomechanics of collagen molecules

    E-print Network

    Chang, Shu-Wei

    Collagenous tissues, made of collagen molecules, such as tendon and bone, are intriguing materials that have the ability to respond to mechanical forces by altering their structures from the molecular level up, and convert ...

  2. Symmetric Encryption The symmetric setting considers two parties who share a key and will use this key to imbue commu-

    E-print Network

    Bernstein, Daniel

    the encryption algorithm is invoked on inputs K, M, it computes a ciphertext based on K, M and the current stateChapter 5 Symmetric Encryption The symmetric setting considers two parties who share a key and will use this key to imbue commu- nicated data with various security attributes. The main security goals

  3. Exotic diatomic molecules of cesium

    NASA Astrophysics Data System (ADS)

    Tallant, Jonathan E.

    The observation of a new, polar class of homonuclear diatomic molecules, called trilobite molecules, is presented. The molecules have permanent electric dipole moments of ˜ 20--100 Debye. The observations are in agreement with calculations carried out by our collaborators at the Institute of Theoretical Atomic, Molecular, and Optical Physics (ITAMP), at Harvard University. The unique mechanism that binds the molecules will be described. The molecules are not observable inside of a Magneto-Optical Trap (MOT) due to the low density of trapped atoms, ˜ 1 x 1010 cm -3. This thesis also describes the improvements to the apparatus in an effort to increase the density of trapped atoms. The improvements are two-fold. First, a system to slow an atomic beam using the Zeeman effect is described. The slowed atomic beam is used to load the MOT instead of from a background vapor, enhancing both the loading rate and the number of trapped atoms. A Monte Carlo simulation of the slowing process is presented. Second, an optical dipole trapping system has been developed and successfully implemented which captures atoms at a temperature of ˜ 40 muK and at a density of ˜ 2 x 1013 cm-3. The increase in density augments two-body event rates by a factor of ˜ 4 x 106, and allows experiments to probe smaller interaction distances. This is demonstrated by the photoassociation of these exotic trilobite molecules.

  4. Race to Top Draws out New Suitors

    ERIC Educational Resources Information Center

    McNeil, Michele

    2012-01-01

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

  5. World average top-quark mass

    SciTech Connect

    Glenzinski, D.; /Fermilab

    2008-01-01

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

  6. Top 12 Web Resources for 2012

    ERIC Educational Resources Information Center

    Gonzales, Lisa; Vodicka, Devin

    2012-01-01

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

  7. Controlling Severe Curly Top in Sugarbeets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Controlling curly top in sugarbeet has been industry priority in the western United States since the 1920s. Curly top is a virus disease that is vectored by the beet leafhopper. If the beet leafhopper moves into commercial fields early in the season, virus is more likely to be transmitted to sugar...

  8. CP violation in top-quark physics

    E-print Network

    German Valencia

    2010-07-27

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

  9. The Sakai Spinner: A Paperclip Top

    ERIC Educational Resources Information Center

    Corrao, Christian T.

    2014-01-01

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

  10. Top Tips for Accessing Oxford's Information Resources

    E-print Network

    Oxford, University of

    , electronic journals and books Top Tip 1: Attend the Bodleian induction sessions for your subject #12;Oxford · Access to electronic databases and journals #12;Library Catalogue #12;Library Catalogue Top Tip 3 : Log ­ majority of the college's modern books Hulme ­ history, politics and geography (access from Main Library

  11. Top Tips for Accessing Oxford's Information Resources

    E-print Network

    Oxford, University of

    , electronic journals and books Top Tip 1: Attend the induction session in your departmental library #12;Oxford · Access to electronic databases and journals #12;Library Catalogue #12;Library Catalogue Top Tip 3 : Log primary sections: Main ­ majority of the college's modern books Hulme ­ history, politics and geography

  12. 1 2 3 4 5 Top Pharmacy

    E-print Network

    Sachs, Frederick

    or multidisciplinary research opportunities. " Christopher Daly PharmD/ MBA `12, clinical assistant professor, pharmacy#12;#12;1 2 3 4 5 Top Pharmacy School and World Leader in PK/PD Ranked among the top pharmacy Curriculum and Experiential Education From neighborhood pharmacies to federal regulatory agencies

  13. Top Quark Pair Production at the Tevatron

    SciTech Connect

    Nielsen, Jason

    2005-05-17

    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.

  14. Your Hit Parade: The Top Ten Most

    E-print Network

    Berndt, Bruce C.

    Your Hit Parade: The Top Ten Most Fascinating Formulas in Ramanujan's Lost Notebook George E the TV channel knob to NBC's Your Hit Parade to find out the Top Seven Songs of the week, as deter- mined later, he would be at Trinity College, Cambridge, to discover one of the biggest "hits" in mathematical

  15. Pinch Experiments in a Table Top Generator

    SciTech Connect

    Pavez, Cristian; Moreno, Jose; Soto, Leopoldo; Tarifeno, Ariel

    2009-01-21

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

  16. Water vapor near Venus cloud tops from VIRTIS-H/Venus express observations 2006-2011

    NASA Astrophysics Data System (ADS)

    Cottini, V.; Ignatiev, N. I.; Piccioni, G.; Drossart, P.

    2015-08-01

    This work aims to give a summary of the water vapor at the cloud top of Venus atmosphere using the complete set of observations made using high spectral resolution channel (-H) of Visible and Infrared Thermal Imaging Spectrometer (VIRTIS), on board the ESA Venus Express orbiter, to measure the cloud top altitude and the water vapor abundance near this level. An initial analysis of these measurements by Cottini et al. (2012) was limited to data in 140 orbits in the period 2007-2008. These observations were limited to the Northern hemisphere due to observational geometry in this early part of the mission. In the present paper, the analysis is extended to a larger dataset covering the years 2006-2011, significantly improving the latitudinal coverage. Altitude of the cloud tops, corresponding to unit optical depth at a wavelength of 2.5 ?m, is equal to 69±1 km at low latitudes, and decreases toward the pole to 62-64 km. The water vapor abundance is equal to 3±1 ppm in low latitudes and it increases reaching a maximum of 5±2 ppm at 70-80° of latitude in both hemispheres, with a sharp drop in the polar regions. This can be explained by the specific dynamics of the atmosphere of Venus affecting the distribution of water vapor such as the transfer of water vapor in the Hadley cell and the dynamic in the polar vortex. The average height of the cloud tops and the H2O near this level are symmetric with respect to the equator. As a function of local solar time, the water vapor shows no particular dependence, and the cloud tops exhibit just a weak maximum around noon. Over 5 years of observations the average values of the cloud top altitude and the water vapor were quite stable in low and middle latitudes, while in high latitudes both quantities in 2009-2011 years are systematically higher than in 2006-2008. Short period variations increasing with latitude are observed, from approximately less than ±1 km for cloud tops and ±1 ppm for water vapor in low latitudes to, respectively, ±2 km and ±2 ppm in high latitudes. As a rule there is no correlation between variations of the cloud top altitude, the water vapor content, and the UV brightness. However, numerous examples can be found when UV dark features, with a characteristic size of a few degrees of latitude (several hundred kilometers), coincide with regions of higher cloud tops.

  17. Top properties measurements with the ATLAS detector

    E-print Network

    Neep, Thomas James; The ATLAS collaboration

    2015-01-01

    The top quark is unique among the known quarks in that it decays before it has an opportunity to form hadronic bound states. This makes measurements of its properties particularly interesting as one can access directly the properties of a bare quark. A measurement of the charge asymmetry in top quark pair events are presented. The measurements uses the 7 TeV ATLAS dataset and probes models of physics beyond the Standard Model. A measurement of the correlation between the direction of the spins of top quark pairs is also presented. The measurement agrees with the Standard Model and is used to set limits on the production of the supersymmetric partner of the top quark. In addition, a novel measurement of colour flow in top quark pair events is presented. The measurement uses the jets originating from the W boson and demonstrates the ability of the colour flow observable to distinguish between colour octet and colour singlet final states.

  18. QCD resummations for boosted top production

    E-print Network

    Ferroglia, Andrea; Scott, Darren J; Yang, Li Lin

    2015-01-01

    We present new results for QCD corrections to the top-pair invariant mass and top-quark $p_T$ distributions in boosted top-quark pair production at hadron colliders. They are derived from a formalism which allows the joint resummation of soft and small-mass logarithms at NNLL$'$ order, thus taking into account all potentially large corrections in the boosted regime, where the partonic center-of-mass energy is parameterically much larger than the mass of the top quark. We match these results with those from standard soft-gluon resummation away from the small-mass limit to NNLL order and also with NLO fixed-order calculations, so that our results are valid in the maximum possible range of phase space. The resummation effects on the $p_T$ and top-pair invariant mass distributions are significant, bringing theory predictions into better agreement with experimental data compared to pure NLO calculations.

  19. Thermionic topping of electric power plants

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  20. Protein Identification Using Top-Down

    SciTech Connect

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

    2012-06-01

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

  1. TOP500 Supercomputers for June 2002

    SciTech Connect

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

    2002-06-20

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

  2. Thermodynamic motivations of spherically symmetric static metrics

    E-print Network

    H. Moradpour; S. Nasirimoghadam

    2015-11-18

    Bearing the thermodynamic arguments together with the two definitions of mass in mind, we try to find metrics with spherical symmetry. We consider the adiabatic condition along with the Gong-Wang mass, and evaluate the $g_{rr}$ element which points to a null hypersurface. In addition, we generalize the thermodynamics laws to this hypersurface to find its temperature and thus the corresponding surface gravity which enables us to get a relation for the $g_{tt}$ element. Moreover, we investigate the mathematical and physical properties of the discovered metric in the Einstein relativity framework which shows that the primary mentioned null hypersurface is an event horizon. The obtained energy-momentum tensor equals the energy-momentum tensor of a polytropic black hole embedded into an anti-de Sitter background. We also show that if one considers the Misner-Sharp mass in the calculations, the Schwarzschild metric will be got. The relationship between the two mass definitions in each metric is studied. The results of considering the geometrical surface gravity are also addressed. Our investigation shows that the geometrical surface gravity's definition is not always compatible with the validity of the first law of thermodynamics on the horizons of spherically symmetric static metrics.

  3. Surface gravity in dynamical spherically symmetric spacetimes

    E-print Network

    Fodor, Gyula; Oshiro, Y; Tomimatsu, A

    1996-01-01

    A definition of surface gravity at the apparent horizon of dynamical spherically symmetric spacetimes is proposed. It is based on a unique foliation by ingoing null hypersurfaces. The function parametrizing the hypersurfaces can be interpreted as the phase of a light wave uniformly emitted by some far-away static observer. The definition gives back the accepted value of surface gravity in the static case by virtue of its nonlocal character. Although the definition is motivated by the behavior of outgoing null rays, it turns out that there is a simple connection between the generalized surface gravity, the acceleration of any radially moving observer, and the observed frequency change of the infalling light signal. In particular, this gives a practical and simple method of how any geodesic observer can determine surface gravity by measuring only the redshift of the infalling light wave. The surface gravity can be expressed as an integral of matter field quantities along an ingoing null line, which shows that i...

  4. Time-Symmetric Rolling Tachyon Profile

    E-print Network

    Matheson Longton

    2015-06-12

    We investigate the tachyon profile of a time-symmetric rolling tachyon solution to open string field theory. We algebraically construct the solution of [arXiv:0707.4472] at 6th order in the marginal parameter, and numerically evaluate the corresponding tachyon profile as well as the action and several correlation functions containing the equation of motion. We find that the marginal operator's singular self-OPE is properly regularized and all quantities we examine are finite. In contrast to the widely studied time-asymmetric case, the solution depends nontrivially on the strength of the deformation parameter. For example, we find that the number and period of oscillations of the tachyon field changes as the strength of the marginal deformation is increased. We use the recent renormalization scheme of [arXiv:1412.3466], which contains two free parameters. At finite deformation parameter the tachyon profile depends on these parameters, while when the deformation parameter is small, the solution becomes insensitive to them and behaves like previously studied time-asymmetric rolling tachyon solutions. We also show that convergence of perturbation series is not as straightforward as in the time-asymmetric case with regular OPE, and find evidence that it may depend on the renormalization constants.

  5. Explosive condensation in symmetric mass transport models

    NASA Astrophysics Data System (ADS)

    Chau, Yu-Xi; Connaughton, Colm; Grosskinsky, Stefan

    2015-11-01

    We study the dynamics of condensation in a misanthrope process with nonlinear jump rates and factorized stationary states. For large enough density, it is known that such models have a phase separated state, with a non-zero fraction of the total mass concentrating in a single lattice site. It has been established in [B Waclaw and M R Evans, Phys. Rev. Lett., 108(7):070601, 2012] for asymmetric dynamics that such processes exhibit explosive condensation, where the time to reach the stationary state vanishes with increasing system size. This constitutes a spatially extended version of instantaneous gelation which has previously been studied only in mean-field coagulation models. We show that this phenomenon also occurs for symmetric dynamics in one dimension if the non-linearity is strong enough, and we find a coarsening regime where the time to stationarity diverges with the system size for weak non-linearity. In higher space dimensions explosive condensation is expected to be generic for all parameter values. Our results are based on heuristic mean field arguments which are confirmed by simulation data.

  6. Time-symmetric rolling tachyon profile

    NASA Astrophysics Data System (ADS)

    Longton, Matheson

    2015-09-01

    We investigate the tachyon profile of a time-symmetric rolling tachyon solution to open string field theory. We algebraically construct the solution of [1] at 6th order in the marginal parameter, and numerically evaluate the corresponding tachyon profile as well as the action and several correlation functions containing the equation of motion. We find that the marginal operator's singular self-OPE is properly regularized and all quantities we examine are finite. In contrast to the widely studied time-asymmetric case, the solution depends nontrivially on the strength of the deformation parameter. For example, we find that the number and period of oscillations of the tachyon field changes as the strength of the marginal deformation is increased. We use the recent renormalization scheme of [2], which contains two free parameters. At finite deformation parameter the tachyon profile depends on these parameters, while when the deformation parameter is small, the solution becomes insensitive to them and behaves like previously studied time-asymmetric rolling tachyon solutions. We also show that convergence of perturbation series is not as straightforward as in the time-asymmetric case with regular OPE, and find evidence that it may depend on the renormalization constants.

  7. Drift waves in helically symmetric stellarators

    SciTech Connect

    Rafiq, T.; Hegna, C.

    2005-11-15

    The local linear stability of electron drift waves and ion temperature gradient modes (ITG) is investigated in a quasihelically symmetric (QHS) stellarator and a conventional asymmetric (Mirror) stellarator. The geometric details of the different equilibria are emphasized. Eigenvalue equations for the models are derived using the ballooning mode formalism and solved numerically using a standard shooting technique in a fully three-dimensional stellarator configuration. While the eigenfunctions have a similar shape in both magnetic geometries, they are slightly more localized along the field line in the QHS case. The most unstable electron drift modes are strongly localized at the symmetry points (where stellarator symmetry is present) and in the regions where normal curvature is unfavorable and magnitude of the local magnetic shear and magnetic field is minimum. The presence of a large positive local magnetic shear in the bad curvature region is found to be destabilizing. Electron drift modes are found to be more affected by the normal curvature than by the geodesic curvature. The threshold of stability of the ITG modes in terms of {eta}{sub i} is found to be 2/3 in this fluid model consistent with the smallest threshold for toroidal geometry with adiabatic electrons. Optimization to favorable drift wave stability has small field line curvature, short connection lengths, the proper combination of geodesic curvature and local magnetic shear, large values of local magnetic shear, and the compression of flux surfaces in the unfavorable curvature region.

  8. Spherically symmetric inhomogeneous model with Chaplygin gas

    SciTech Connect

    Panigrahi, D.; Chatterjee, S. E-mail: chat_sujit1@yahoo.com

    2011-10-01

    We investigate the late time acceleration with a Chaplygin type of gas in spherically symmetric inhomogeneous model. At the early phase we get Einstien-de Sitter type of solution generalised to inhomogeneous spacetime. But at late stage of the evolution our solutions admit the accelerating nature of the universe. For a large scale factor our model behaves like a ?CDM model. We calculate the deceleration parameter for this anisotropic model, which, unlike its homogeneous counterpart, shows that the flip is not synchronous occurring early at the outer shells. This is in line with other physical processes in any inhomogeneous models. Depending upon initial conditions our solution also gives bouncing universe. In the absence of inhomogeneity our solution reduces to wellknown solutions in homogeneous case. We have also calculated the effective deceleration parameter in terms of Hubble parameter. The whole situation is later discussed with the help of wellknown Raychaudhury equation and the results are compared with the previous case. This work is an extension of our recent communication where an attempt was made to see if the presence of extra dimensions and/or inhomogeneity can trigger an inflation in a matter dominated Lemaître Tolman Bondi model.

  9. Medical Applications of Leukocyte Surface Molecules—the CD molecules

    PubMed Central

    Zola, Heddy

    2006-01-01

    Leukocytes are the cells of the immune system and are centrally involved in defense against infection, in autoimmune disease, allergy, inflammation, and in organ graft rejection. Lymphomas and leukemias are malignancies of leukocytes, and the immune system is almost certainly involved in most other cancers. Each leukocyte expresses a selection of cell surface glycoproteins and glycolipids which mediate its interaction with antigen, with other components of the immune system, and with other tissues. It is therefore not surprising that the leukocyte surface molecules (CD molecules) have provided targets for diagnosis and therapy. Among the “celebrities” are CD20, a target for lymphoma therapeutic antibodies which earns $2 billion annually (and makes a significant difference to lymphoma patients), and CD4, the molecule used by the human immunodeficiency virus (HIV) as an entry portal into cells of the immune system. This short review provides a background to the CD molecules and antibodies against them, and summarizes research, diagnostic, and therapeutic applications of antibodies against these molecules. PMID:17380197

  10. MHD Integrated Topping Cycle Project

    SciTech Connect

    Not Available

    1992-02-01

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

  11. Top-of-Rail lubricant

    SciTech Connect

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

    2000-07-14

    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.

  12. Realizing PT-symmetric BEC subsystems in closed hermitian systems

    E-print Network

    Robin Gutöhrlein; Jan Schnabel; Ibrokhim Iskandarov; Holger Cartarius; Jörg Main; Günter Wunner

    2015-07-06

    In open double-well Bose-Einstein condensate systems which balance in- and outfluxes of atoms and which are effectively described by a non-hermitian PT-symmetric Hamiltonian PT-symmetric states have been shown to exist. PT-symmetric states obey parity and time reversal symmetry. We tackle the question of how the in- and outfluxes can be realized and introduce a hermitian system in which two PT-symmetric subsystems are embedded. This system no longer requires an in- and outcoupling to and from the environment. We show that the subsystems still have PT-symmetric states. In addition we examine what degree of detail is necessary to correctly model the PT-symmetric properties and the bifurcation structure of such a system. We examine a four-mode matrix model and a system described by the full Gross-Pitaevskii equation in one dimension. We see that a simple matrix model correctly describes the qualitative properties of the system. For sufficiently isolated wells there is also quantitative agreement with the more advanced system descriptions. We also investigate which properties the wave functions of a system must fulfil to allow for PT-symmetric states. In particular the requirements for the phase difference between different parts of the system are examined.

  13. Rational design and gas-phase characterization of molecular capsules by self-assembly of a symmetric hexasubstituted benzene with seven-membered lactams.

    PubMed

    Baillargeon, Pierre; Dory, Yves L

    2008-04-30

    A novel very simple C3-symmetric lactam has been rationally designed to self-assemble as dimers or larger platonic solid capsules. Its core flat benzene ring bears three seven-membered lactams, resulting in tripod molecules that aggregate into robust tetrameric capsules. The self-assembly process was templated by tetraethylammonium cations and proven to be reversible by ESI spectroscopy in various solvents. PMID:18386895

  14. (M-theory-)Killing spinors on symmetric spaces

    NASA Astrophysics Data System (ADS)

    Hustler, Noel; Lischewski, Andree

    2015-08-01

    We show how the theory of invariant principal bundle connections for reductive homogeneous spaces can be applied to determine the holonomy of generalised Killing spinor covariant derivatives of the form D = ? + ? in a purely algebraic and algorithmic way, where ? : TM ? ??(TM) is a left-invariant homomorphism. Specialising this to the case of symmetric M-theory backgrounds (i.e., (M, g, F) with (M, g) an eleven-dimensional Lorentzian (locally) symmetric space and F an invariant closed 4-form), we derive several criteria for such a background to preserve some supersymmetry and consequently find all supersymmetric symmetric M-theory backgrounds.

  15. Multiple Point-Symmetric Ejections in IC 4634

    E-print Network

    Martin A. Guerrero; Luis F. Miranda; You-Hua Chu

    2003-10-14

    We present a spatio-kinematical study of the planetary nebula (PN) IC 4634 which has experienced several episodes of point-symmetric ejections oriented at different directions. The nebula displays two S-shaped low-ionization arcs that are probably related to two relatively recent point-symmetric ejections, the outer S-shaped arc representing a beautiful example of a bow-shock resolved in a PN. We report here the discovery of an arc-like string of knots at larger distances from IC 4634 central star that represents a much earlier point-symmetric ejection.

  16. Geometric characteristics of aberrations of plane-symmetric optical systems

    SciTech Connect

    Lu Lijun; Deng Zhiyong

    2009-12-20

    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.

  17. Discovery of single top quark production

    SciTech Connect

    Gillberg, Dag

    2009-05-01

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

  18. Measuring an antibody affinity distribution molecule by molecule

    SciTech Connect

    Bradbury, Andrew M; Werner, James H; Temirov, Jamshid

    2008-01-01

    Single molecule fluorescence mIcroscopy was used to observe the binding and unbinding of hapten decorated quantum dots with individual surface immobilized antibodies. The fluorescence time history from an individual antibody site can be used to calculate its binding affinity. While quantum dot blinking occurs during these measurements, we describe a simple empirical method to correct the apparent/observed affinity to account for the blinking contribution. The combination of many single molecule affinity measurements from different antibodies yields not only the average affinity, it directly measures the full shape and character of the surface affinity distribution function.

  19. Protonation of heterocyclic aromatic molecules

    NASA Astrophysics Data System (ADS)

    Lorenz, Ulrich Joseph; Lemaire, Joel; Maitre, Philippe; Crestoni, Maria-Elisa; Fornarini, Simonetta; Dopfer, Otto

    2007-11-01

    Protonated furan (C4H5O+, furanH+) and protonated pyrrole (C4H6N+, pyrroleH+) are generated by chemical ionization of the respective parent molecules in the cell of an FT-ICR mass spectrometer using CH5+/C2H5+ as protonating agents. The protonation site is investigated by resonant infrared multiphoton dissociation (IRMPD) spectroscopy in the 900-1700 cm-1 fingerprint range employing the free electron laser (FEL) at the Centre Laser Infrarouge Orsay (CLIO). Comparison with quantum chemical calculations at the B3LYP/6-311G(2df, 2pd) level of theory demonstrates unambiguously that only the C[alpha] protonated isomers are observed, which correspond to the global minima on the potential energy surfaces of both protonated heterocyclic molecules. Spectroscopic features corresponding to protonation at the C[beta] atom or at the heteroatom are not detected. The IRMPD spectra correspond to the first spectroscopic identification of both protonated heterocyclic molecules in the gas phase. During the course of the experiments, the IRMPD spectrum of the furan radical cation (C4H4O+, furan+) has been detected as well. Comparison of the IR spectra of the neutral molecules with the IRMPD spectra of the radical cation and the protonated species reveals the effects of both ionization and protonation on the structural properties of these fundamental heterocyclic molecules.

  20. Electrical conduction through DNA molecule.

    PubMed

    Abdalla, S

    2011-09-01

    Several disorder parameters, inside the DNA molecule, lead to localization of charge carriers inside potential wells in the lowest unoccupied and highest occupied molecular orbits (LUMO and HOMO) which affects drastically the electrical conduction through the molecule, and demonstrates that the band carriers play an essential role in the conduction mechanism. So, a model is presented to shed light on the role of electrons of the LUMO in the electrical conduction through the DNA molecule. DC-, AC-conductivity and dielectric permittivity experimental data are well fitted with the presented model giving evidence that the free carriers in the LUMO and HOMO are responsible to make the DNA molecule conductor, insulator or semiconductor. The obtained results show that the localized charge carriers in the DNA molecule are characterized by four different types of relaxation phenomena which are thermally activated by corresponding four activation energies at 0.56 eV, 0.33 eV, 0.24 eV, and 0.05 eV respectively. Moreover, the calculations after the model, at room temperature, show that the time of the relaxation times of the current carriers are in the order of 5 × 10(-2)s, 1.74 × 10(-4)s, 5 × 10(-7)s, and 1.6 × 10(-10)s, respectively. PMID:21396395

  1. Analyzing Magnetic Molecules Using TDR

    NASA Astrophysics Data System (ADS)

    Yeninas, Steven; Prozorov, Ruslan; Luban, Marshall

    2009-11-01

    Since the early nineties, much interest has grown in the field of magnetic molecules due to the fact that at suitably low temperatures, intermolecular interactions can be ignored. As a result, studying crystalline samples can be reduced to analyzing the discrete spectrum of magnetic energy levels within an individual molecule. As the size and complexity of magnetic molecules continues to grow, we see that low temperature DC magnetization measurements are restricted to regions of ground state level crossings, demanding a more detailed experimental technique. However, using a tunnel diode resonator (TDR) to measure the dynamic magnetic susceptibility in the millikelvin range, we can probe the magnetic spectrum in both the ground state and low-lying excited states. The TDR technique has recently been used to investigate the magnetic molecules Cr12Cu2 and Cr10Cu2. When compared with theoretical quantum Monte Carlo (QMC) simulations, we find the TDR results to be in excellent agreement with the predicted energy spectrum. This demonstrates that the QMC model can be a valuable quantitative tool for predicting properties of magnetic molecules; as well, the TDR technique is demonstrated to be a unique and powerful tool for analyzing the magnetic spectrum.

  2. Specific features of the two-photon absorption of cationic symmetric polymethine dyes

    NASA Astrophysics Data System (ADS)

    Svetlichny?, V. A.; Bazyl', O. K.; Artyukhov, V. Ya.; Kopylova, T. N.; Derevyanko, N. A.; Ishchenko, A. A.

    2007-11-01

    The two-photon absorption of a number of cationic symmetric polymethine dyes based on 3H-indolium and benzothiazolium is experimentally studied upon excitation by nanosecond radiation from a Nd:YAG laser (1064 nm, 12 ns). The two-photon absorption cross section of dye molecules is determined by the two-quantum standard method. The influence of the spectral-luminescent properties and structure of the polymethine dyes on the two-photon absorption cross section is discussed. It is shown that, upon excitation in the range of the long-wavelength band of the dyes studied (the S 0 ? S 1 transition), the maximum of their two-photon absorption is blue shifted. The reasons for a considerable increase in the two-photon absorption of symmetric polymethine dyes upon their excitation in the range of the S 2 state are discussed. Using the data of quantum-chemical calculations, it is shown that, along with changes in the selection rules for two-photon transitions, this increase is connected with an increase in the size of the delocalized ? electron cloud of HOMOs involved in the S 0 ? S 2 transition.

  3. A Symmetrical Tetramer for S. aureus Pyruvate Carboxylase in Complex with Coenzyme A

    SciTech Connect

    Yu, L.; Xiang, S; Lasso, G; Gil, D; Valle, M; Tong, L

    2009-01-01

    Pyruvate carboxylase (PC) is a conserved metabolic enzyme with important cellular functions. We report crystallographic and cryo-electron microscopy (EM) studies of Staphylococcus aureus PC (SaPC) in complex with acetyl-CoA, an allosteric activator, and mutagenesis, biochemical, and structural studies of the biotin binding site of its carboxyltransferase (CT) domain. The disease-causing A610T mutation abolishes catalytic activity by blocking biotin binding to the CT active site, and Thr908 might play a catalytic role in the CT reaction. The crystal structure of SaPC in complex with CoA reveals a symmetrical tetramer, with one CoA molecule bound to each monomer, and cryo-EM studies confirm the symmetrical nature of the tetramer. These observations are in sharp contrast to the highly asymmetrical tetramer of Rhizobium etli PC in complex with ethyl-CoA. Our structural information suggests that acetyl-CoA promotes a conformation for the dimer of the biotin carboxylase domain of PC that might be catalytically more competent.

  4. Ionization of oriented carbonyl sulfide molecules by intense circularly polarized laser pulses

    SciTech Connect

    Dimitrovski, Darko; Abu-samha, Mahmoud; Madsen, Lars Bojer; Filsinger, Frank; Meijer, Gerard; Kuepper, Jochen; Holmegaard, Lotte; Kalhoej, Line; Nielsen, Jens H.; Stapelfeldt, Henrik

    2011-02-15

    We present combined experimental and theoretical results on strong-field ionization of oriented carbonyl sulfide molecules by circularly polarized laser pulses. The obtained molecular frame photoelectron angular distributions show pronounced asymmetries perpendicular to the direction of the molecular electric dipole moment. These findings are explained by a tunneling model invoking the laser-induced Stark shifts associated with the dipoles and polarizabilities of the molecule and its unrelaxed cation. The focus of the present article is to understand the strong-field ionization of one-dimensionally-oriented polar molecules, in particular asymmetries in the emission direction of the photoelectrons. In the following article [Phys. Rev. A 83, 023406 (2011)] the focus is to understand strong-field ionization from three-dimensionally-oriented asymmetric top molecules, in particular the suppression of electron emission in nodal planes of molecular orbitals.

  5. Dissociation and Decay of Ultracold Sodium Molecules We have studied the dissociation and decay of ultracold molecules. Sodium molecules

    E-print Network

    Dissociation and Decay of Ultracold Sodium Molecules We have studied the dissociation and decay of ultracold molecules. Sodium molecules were formed in a highly excited vibrational state by recombining two cooling. Dissociation energy of sodium molecules as a function of magnetic field ramp rate. The dashed

  6. Direct Measurement and Chemical Speciation of Top Ring Zone Liquid During Engine Operation

    SciTech Connect

    Splitter, Derek A; Burrows, Barry Clay; Lewis Sr, Samuel Arthur

    2015-01-01

    The present manuscript consists of proof of concept experiments involving direct measurements and detailed chemical speciation from the top ring zone of a running engine. The work uses a naturally aspirated single cylinder utility engine that has been modified to allow direct liquid sample acquisition from behind the top ring. Samples were analyzed and spectated using gas chromatographic techniques. Results show that the liquid mixture in the top ring zone is neither neat lubricant nor fuel but a combination of the two with unique chemical properties. At the tested steady state no-load operating condition, the chemical species of the top ring zone liquid were found to be highly dependent on boiling point, where both low reactivity higher boiling point fuel species and lubricant are observed to be the dominant constituents. The results show that at least for the tested condition, approximately 25% of the top ring zone is comprised of gasoline fuel like molecules, which are dominated by high octane number aromatic species, while the remainder of the liquid is comprised of lubricant like species.

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

    SciTech Connect

    DAWSON,S.

    2002-06-01

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

  8. The lack of large compact symmetric objects

    NASA Astrophysics Data System (ADS)

    Augusto, P.

    2009-02-01

    In recent years, `baby' (< 103 yr) and `young' (103-105 yr) radio galaxies have been found and classified, although their numbers are still small (tens). Also, they have many different names, depending on the type of survey and scientific context in which they were found: compact steep spectrum sources (CSS), giga-Hertz peaked spectrum sources (GPS) and compact-medium symmetric objects (C-MSO). The latter have the radio galaxy structure more obvious and correspond to the `babies' (CSOs; < 1 kpc) and `young' (MSOs; 1-15 kpc) radio galaxies. The log-size distribution of CSOs shows a sharp drop at 0.3 kpc. This trend continues through flat-spectrum MSOs (over the full 1-15 kpc size range). In order to find out if this lack of large CSOs and flat-spectrum MSOs is due to poor sampling (lack of surveys that probe efficiently the 0.3-15 kpc size range) and/or has physical meaning (e.g. if the lobes of CSOs expand as they grow and age, they might become CSSs, `disappearing' from the flat-spectrum MSO statistics), we have built a sample of 157 flat-spectrum radio sources with structure on ˜0.3-15 kpc scales. We are using new, archived and published data to produce and inspect hundreds of multi-frequency multi-instrument maps and models. We have already found 13 new secure CSO/MSOs. We expect to uncover ˜30-40 new CSOs and MSOs, most on the 0.3-15 kpc size range, when our project is complete.

  9. Recent advances in symmetric and network dynamics

    NASA Astrophysics Data System (ADS)

    Golubitsky, Martin; Stewart, Ian

    2015-09-01

    We summarize some of the main results discovered over the past three decades concerning symmetric dynamical systems and networks of dynamical systems, with a focus on pattern formation. In both of these contexts, extra constraints on the dynamical system are imposed, and the generic phenomena can change. The main areas discussed are time-periodic states, mode interactions, and non-compact symmetry groups such as the Euclidean group. We consider both dynamics and bifurcations. We summarize applications of these ideas to pattern formation in a variety of physical and biological systems, and explain how the methods were motivated by transferring to new contexts René Thom's general viewpoint, one version of which became known as "catastrophe theory." We emphasize the role of symmetry-breaking in the creation of patterns. Topics include equivariant Hopf bifurcation, which gives conditions for a periodic state to bifurcate from an equilibrium, and the H/K theorem, which classifies the pairs of setwise and pointwise symmetries of periodic states in equivariant dynamics. We discuss mode interactions, which organize multiple bifurcations into a single degenerate bifurcation, and systems with non-compact symmetry groups, where new technical issues arise. We transfer many of the ideas to the context of networks of coupled dynamical systems, and interpret synchrony and phase relations in network dynamics as a type of pattern, in which space is discretized into finitely many nodes, while time remains continuous. We also describe a variety of applications including animal locomotion, Couette-Taylor flow, flames, the Belousov-Zhabotinskii reaction, binocular rivalry, and a nonlinear filter based on anomalous growth rates for the amplitude of periodic oscillations in a feed-forward network.

  10. Fluctuation phenomena in structurally symmetric polymer blends

    NASA Astrophysics Data System (ADS)

    Singh, Chandralekha; Schweizer, Kenneth S.; Yethiraj, Arun

    1995-02-01

    Polymer reference interaction site model theory with the new molecular closures is employed to numerically and analytically study structurally and interaction potential symmetric binary blends. Both the compressibility and free energy routes to the thermodynamics are studied and the issue of thermodynamic consistency is addressed. A variety of non-Flory-Huggins effects, or ``fluctuation phenomena,'' are found. These include nonuniversal renormalization of the critical temperature and effective chi-parameter from their mean field values, composition-dependent chi-parameters, and nonlinear dependence of the inverse osmotic compressibility on inverse temperature. All these fluctuation effects depend on degree of polymerization, N, chain length asymmetry, polymer density, range and precise form of the attractive tail potentials, chain stiffness, and proximity to the phase boundary. Some of the fluctuation effects are intrinsic, i.e., survive in the long chain N?? limit, while others are finite size effects which arise from chain-connectivity-induced coupled local density and long wavelength concentration fluctuations. Due to the multiple sources of the fluctuation effects, even asymptotic finite size effects can appear ``intrinsic'' over extended ranges of N. Comparison with lattice Monte Carlo simulations of Deutsch and Binder shows good agreement with the theoretical predictions. All the fluctuation effects can be understood in simple terms by examining the enthalpy of mixing and local interchain correlations. The key physical process is thermally driven local interchain rearrangements corresponding to the formation of diffuse interfaces and clusters or droplets. Analytic results are derived using the Gaussian thread model, which provides a simple physical understanding of the origin of the numerically determined fluctuation effects. In the long chain limit the predictions for the thread blend are shown to be exactly thermodynamically consistent which is a unique circumstance for liquid state theories. The relation of the blend fluctuation stabilization process to the corresponding diblock copolymer problem is briefly discussed.

  11. Static field ionization rates for multi-electron atoms and small molecules

    NASA Astrophysics Data System (ADS)

    Pramod Majety, Vinay; Scrinzi, Armin

    2015-12-01

    We present an application of the hybrid anti-symmetrized coupled channels approach to compute static field ionization rates for multi-electron atoms (He, Ne, Ar) and small molecules (H2, N2, CO). While inert gas atoms behave as effective single electron systems, molecules exhibit multi-electron effects in the form of core polarization. It is shown that at moderate field strengths, these effects can be modeled to about 10% accuracy using a few (5–6) channel ansatz. In the case of the CO molecule, description of core polarization is essential for the correct prediction of the maximum ionization direction and our converged results are in good agreement with the experimental measurements.

  12. Small Molecule Fluoride Toxicity Agonists

    PubMed Central

    Nelson1, James W.; Plummer, Mark S.; Blount, Kenneth F.; Ames, Tyler D.; Breaker, Ronald R.

    2015-01-01

    SUMMARY Fluoride is a ubiquitous anion that inhibits a wide variety of metabolic processes. Here we report the identification of a series of compounds that enhance fluoride toxicity in Escherichia coli and Streptococcus mutans. These molecules were isolated by using a high-throughput screen (HTS) for compounds that increase intracellular fluoride levels as determined via a fluoride riboswitch-reporter fusion construct. A series of derivatives were synthesized to examine structure-activity relationships, leading to the identification of compounds with improved activity. Thus, we demonstrate that small molecule fluoride toxicity agonists can be identified by HTS from existing chemical libraries by exploiting a natural fluoride riboswitch. In addition, our findings suggest that some molecules might be further optimized to function as binary antibacterial agents when combined with fluoride. PMID:25910244

  13. Electric Deflection of Rotating Molecules

    E-print Network

    Gershnabel, E

    2010-01-01

    We provide a theory of the deflection of polar and non-polar rotating molecules by inhomogeneous static electric field. Rainbow-like features in the angular distribution of the scattered molecules are analyzed in detail. Furthermore, we demonstrate that one may efficiently control the deflection process with the help of short and strong femtosecond laser pulses. In particular the deflection process may by turned-off by a proper excitation, and the angular dispersion of the deflected molecules can be substantially reduced. We study the problem both classically and quantum mechanically, taking into account the effects of strong deflecting field on the molecular rotations. In both treatments we arrive at the same conclusions. The suggested control scheme paves the way for many applications involving molecular focusing, guiding, and trapping by inhomogeneous fields.

  14. Electric Deflection of Rotating Molecules

    E-print Network

    E. Gershnabel; I. Sh. Averbukh

    2010-10-20

    We provide a theory of the deflection of polar and non-polar rotating molecules by inhomogeneous static electric field. Rainbow-like features in the angular distribution of the scattered molecules are analyzed in detail. Furthermore, we demonstrate that one may efficiently control the deflection process with the help of short and strong femtosecond laser pulses. In particular the deflection process may by turned-off by a proper excitation, and the angular dispersion of the deflected molecules can be substantially reduced. We study the problem both classically and quantum mechanically, taking into account the effects of strong deflecting field on the molecular rotations. In both treatments we arrive at the same conclusions. The suggested control scheme paves the way for many applications involving molecular focusing, guiding, and trapping by inhomogeneous fields.

  15. Formation of Ultracold Polar Molecules

    NASA Astrophysics Data System (ADS)

    Taylor-Juarros, E.; Côté, R.; Kirby, K.

    2002-05-01

    A variety of experimental techniques have been employed to create a number of ultracold molecules, including CaH, Na_2, K_2, Cs_2, Rb2 and CO. Novel effects are predicted to occur in samples of ultracold polar molecules.(L. Santos et al.), Phys. Rev. Lett. 85, 1791 (2000). We present calculations of the formation rate of ultracold hydrides (LiH, NaH, KH, RbH, and CsH), using the most accurate molecular potentials and dipole moments available. We show that these polar molecules can be produced in selected vibrational and rotational states by stimulated radiative association in a mixture of ultracold hydrogen and alkali metal atoms. We study the properties of these atomic mixtures as well as those of the hydrides, and explore the effect of shape resonances on the formation rates. [2ex] *Supported by NSF

  16. Top quark properties from the Tevatron

    SciTech Connect

    Klute, Markus; /MIT, LNS

    2006-05-01

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

  17. Top quark mass measurement at the Tevatron

    SciTech Connect

    Guimaraes da Costa, Joao; /Harvard U.

    2004-12-01

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

  18. Precision Determination of the Top Quark Mass

    SciTech Connect

    Movilla Fernandez, Pedro A.; /LBL, Berkeley

    2007-05-01

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

  19. Top Quark Production at the Tevatron

    SciTech Connect

    Mietlicki, David J.

    2011-12-01

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

  20. Accommodation of a highly symmetric core within a symmetric protein superfold

    PubMed Central

    Brych, Stephen R.; Kim, Jaewon; Logan, Timothy M.; Blaber, Michael

    2003-01-01

    An alternative core packing group, involving a set of five positions, has been introduced into human acidic FGF-1. This alternative group was designed so as to constrain the primary structure within the core region to the same threefold symmetry present in the tertiary structure of the protein fold (the ?-trefoil superfold). The alternative core is essentially indistinguishable from the WT core with regard to structure, stability, and folding kinetics. The results show that the ?-trefoil superfold is compatible with a threefold symmetric constraint on the core region, as might be the case if the superfold arose as a result of gene duplication/fusion events. Furthermore, this new core arrangement can form the basis of a structural “building block” that can greatly simplify the de novo design of ?-trefoil proteins by using symmetric structural complementarity. Remaining asymmetry within the core appears to be related to asymmetry in the tertiary structure associated with receptor and heparin binding functionality of the growth factor. PMID:14627732

  1. Topological States in Partially-PT -Symmetric Azimuthal Potentials

    NASA Astrophysics Data System (ADS)

    Kartashov, Yaroslav V.; Konotop, Vladimir V.; Torner, Lluis

    2015-11-01

    We introduce partially-parity-time (p PT ) -symmetric azimuthal potentials composed from individual PT -symmetric cells located on a ring, where two azimuthal directions are nonequivalent in a sense that in such potential excitations carrying topological dislocations exhibit different dynamics for different directions of energy circulation in the initial field distribution. Such nonconservative ratchetlike structures support rich families of stable vortex solitons in cubic nonlinear media, whose properties depend on the sign of the topological charge due to the nonequivalence of azimuthal directions. In contrast, oppositely charged vortex solitons remain equivalent in similar fully-P T -symmetric potentials. The vortex solitons in the p P T - and P T -symmetric potentials are shown to feature qualitatively different internal current distributions, which are described by different discrete rotation symmetries of the intensity profiles.

  2. Symmetric multimodal interaction applied to database design and normalization

    E-print Network

    Oleinik, James Roy

    2010-01-01

    A normal conversation between two people is typically multimodal, using both speech and gestures to effect communication. It is also symmetric because there is two-way multimodal interaction between the two parties. In ...

  3. Symmetric Pin Diversion Detection using a Partial Defect Detector (PDET)

    SciTech Connect

    Sitaraman, S; Ham, Y S

    2009-06-01

    Since the signature from the Partial Defect Detector (PDET) is principally dependent on the geometric layout of the guide tube locations, the capability of the technique in detecting symmetric diversion of pins needs to be determined. The Monte Carlo simulation study consisted of cases where pins were removed in a symmetric manner and the resulting signatures were examined. In addition to the normalized gamma-to-neutron ratios, the neutron and gamma signatures normalized to their maximum values, were also examined. Examination of the shape of the three curves as well as of the peak-to-valley differences in excess of the maximum expected in intact assemblies, indicated pin diversion. A set of simulations with various symmetric patterns of diversion were examined. The results from these studies indicated that symmetric diversions as low as twelve percent could be detected by this methodology.

  4. 47 CFR 51.711 - Symmetrical reciprocal compensation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 3 2013-10-01 2013-10-01 false Symmetrical reciprocal compensation. 51.711 Section 51.711 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES (CONTINUED) INTERCONNECTION Reciprocal Compensation for Transport and Termination of...

  5. 47 CFR 51.711 - Symmetrical reciprocal compensation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 3 2012-10-01 2012-10-01 false Symmetrical reciprocal compensation. 51.711 Section 51.711 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES (CONTINUED) INTERCONNECTION Reciprocal Compensation for Transport and Termination of...

  6. Topological States in Partially-PT-Symmetric Azimuthal Potentials.

    PubMed

    Kartashov, Yaroslav V; Konotop, Vladimir V; Torner, Lluis

    2015-11-01

    We introduce partially-parity-time (pPT)-symmetric azimuthal potentials composed from individual PT-symmetric cells located on a ring, where two azimuthal directions are nonequivalent in a sense that in such potential excitations carrying topological dislocations exhibit different dynamics for different directions of energy circulation in the initial field distribution. Such nonconservative ratchetlike structures support rich families of stable vortex solitons in cubic nonlinear media, whose properties depend on the sign of the topological charge due to the nonequivalence of azimuthal directions. In contrast, oppositely charged vortex solitons remain equivalent in similar fully-PT-symmetric potentials. The vortex solitons in the pPT- and PT-symmetric potentials are shown to feature qualitatively different internal current distributions, which are described by different discrete rotation symmetries of the intensity profiles. PMID:26588383

  7. Approximate Noether symmetries from geodetic Lagrangian for plane symmetric spacetimes

    NASA Astrophysics Data System (ADS)

    Ali, Farhad; Feroze, Tooba

    2015-09-01

    Noether symmetries from geodetic Lagrangian for time-conformal plane symmetric spacetime are presented. Here, time-conformal factor is used to find the approximate Noether symmetries. This is a generalization of the idea discussed,5-6 where they obtained approximate Noether symmetries from Lagrangian for a particular plane symmetric static spacetime. In the present paper, the most general plane symmetric static spacetime is considered and perturbed it by introducing a general time-conformal factor e?f(t), where ? is very small which causes the perturbation in the spacetime. Taking the perturbation up to the first-order, we find all Lagrangian for plane symmetric spacetimes for which approximate Noether symmetries exist.

  8. Systems of Differential Equations with Skew-Symmetric, Orthogonal Matrices

    ERIC Educational Resources Information Center

    Glaister, P.

    2008-01-01

    The solution of a system of linear, inhomogeneous differential equations is discussed. The particular class considered is where the coefficient matrix is skew-symmetric and orthogonal, and where the forcing terms are sinusoidal. More general matrices are also considered.

  9. Unscented Kalman Filters for Multiple Target Tracking with Symmetric Measurement

    E-print Network

    Lanterman, Aaron

    1 Unscented Kalman Filters for Multiple Target Tracking with Symmetric Measurement Equations measurement equation approach to multiple target tracking is revisited using unscented Kalman and particle measurement equation implementation relying upon an extended Kalman filter. Counterintuitive results

  10. Symmetric polynomials in information theory: Entropy and subentropy

    SciTech Connect

    Jozsa, Richard; Mitchison, Graeme

    2015-06-15

    Entropy and other fundamental quantities of information theory are customarily expressed and manipulated as functions of probabilities. Here we study the entropy H and subentropy Q as functions of the elementary symmetric polynomials in the probabilities and reveal a series of remarkable properties. Derivatives of all orders are shown to satisfy a complete monotonicity property. H and Q themselves become multivariate Bernstein functions and we derive the density functions of their Levy-Khintchine representations. We also show that H and Q are Pick functions in each symmetric polynomial variable separately. Furthermore, we see that H and the intrinsically quantum informational quantity Q become surprisingly closely related in functional form, suggesting a special significance for the symmetric polynomials in quantum information theory. Using the symmetric polynomials, we also derive a series of further properties of H and Q.

  11. Piezoresistivity in single DNA molecules

    NASA Astrophysics Data System (ADS)

    Bruot, Christopher; Palma, Julio L.; Xiang, Limin; Mujica, Vladimiro; Ratner, Mark A.; Tao, Nongjian

    2015-09-01

    Piezoresistivity is a fundamental property of materials that has found many device applications. Here we report piezoresistivity in double helical DNA molecules. By studying the dependence of molecular conductance and piezoresistivity of single DNA molecules with different sequences and lengths, and performing molecular orbital calculations, we show that the piezoresistivity of DNA is caused by force-induced changes in the ?-? electronic coupling between neighbouring bases, and in the activation energy of hole hopping. We describe the results in terms of thermal activated hopping model together with the ladder-based mechanical model for DNA proposed by de Gennes.

  12. Piezoresistivity in single DNA molecules

    PubMed Central

    Bruot, Christopher; Palma, Julio L.; Xiang, Limin; Mujica, Vladimiro; Ratner, Mark A.; Tao, Nongjian

    2015-01-01

    Piezoresistivity is a fundamental property of materials that has found many device applications. Here we report piezoresistivity in double helical DNA molecules. By studying the dependence of molecular conductance and piezoresistivity of single DNA molecules with different sequences and lengths, and performing molecular orbital calculations, we show that the piezoresistivity of DNA is caused by force-induced changes in the ?–? electronic coupling between neighbouring bases, and in the activation energy of hole hopping. We describe the results in terms of thermal activated hopping model together with the ladder-based mechanical model for DNA proposed by de Gennes. PMID:26337293

  13. VIEW OF PDP TANK TOP, LEVEL 0?, WITH LTR TANK ...

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

    VIEW OF PDP TANK TOP, LEVEL 0?, WITH LTR TANK TOP ON LEFT, LOOKING NORTHEAST. CRANE AND VERTICAL HOISTING ELEMENTS AT TOP - Physics Assembly Laboratory, Area A/M, Savannah River Site, Aiken, Aiken County, SC

  14. VIEW OF PDP TANK TOP, LEVEL 0?, WITH VERTICAL ELEMENTS ...

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

    VIEW OF PDP TANK TOP, LEVEL 0?, WITH VERTICAL ELEMENTS IN BACKGROUND, LTR TANK TOP ON LEFT, AND SHEAVE RACK ELEMENTS AT TOP, LOOKING NORTH - Physics Assembly Laboratory, Area A/M, Savannah River Site, Aiken, Aiken County, SC

  15. 5 CFR 1312.27 - Top secret control.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Top secret control. 1312.27 Section 1312...Classified Information § 1312.27 Top secret control. The EOP Security Officer serves as the Top Secret Control Officer (TSCO) for OMB....

  16. 5 CFR 1312.27 - Top secret control.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Top secret control. 1312.27 Section 1312...Classified Information § 1312.27 Top secret control. The EOP Security Officer serves as the Top Secret Control Officer (TSCO) for OMB....

  17. 5 CFR 1312.27 - Top secret control.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Top secret control. 1312.27 Section 1312...Classified Information § 1312.27 Top secret control. The EOP Security Officer serves as the Top Secret Control Officer (TSCO) for OMB....

  18. 5 CFR 1312.27 - Top secret control.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Top secret control. 1312.27 Section 1312...Classified Information § 1312.27 Top secret control. The EOP Security Officer serves as the Top Secret Control Officer (TSCO) for OMB....

  19. 5 CFR 1312.27 - Top secret control.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Top secret control. 1312.27 Section 1312...Classified Information § 1312.27 Top secret control. The EOP Security Officer serves as the Top Secret Control Officer (TSCO) for OMB....

  20. Optical relative humidity sensor with high sensitivity based on a polyimide-coated symmetrical metal-cladding waveguide.

    PubMed

    Yuan, Wen; Wang, Xianping; Nie, Yiyou; Li, Jun; Sang, Minghuang

    2015-02-01

    An optical structure for relative humidity (RH) sensing based on a polyimide-coated symmetrical metal-cladding waveguide is proposed. The diffusion of water molecules into the polyimide film leads to a combined change of thickness and refractive index. Due to the high sensitivity of ultrahigh-order modes, the interaction between water molecules and polyimide will give rise to a dramatic variation in the reflected light intensity. Our optical RH sensor exhibits a good linearity and a high RH resolution of approximately 0.16% for RH values ranging from 36% to 76%. In addition, it provides a short response time, a favorable stability over a long period, and a small degree of hysteresis. PMID:25967794