Science.gov

Sample records for strangeness excitation functions

  1. Properties of excited charm and charm-strange mesons

    NASA Astrophysics Data System (ADS)

    Godfrey, Stephen; Moats, Kenneth

    2016-02-01

    We calculate the properties of excited charm and charm-strange mesons. We use the relativized quark model to calculate their masses and wave functions that are used to calculate radiative transition partial widths and the 3P0 quark-pair-creation model to calculate their strong decay widths. We use these results to make quark model spectroscopic assignments for recently observed charm and charm-strange mesons. In particular, we find that the properties of the DJ(2550 )0 and DJ*(2600 )0 are consistent with those of the 2 1S0 (c u ¯) and the 2 3S1 (c u ¯) states respectively, and the D1*(2760 )0, D3*(2760 )-,and DJ(2750 )0with those of the 1 3D1 (c u ¯), 1 3D3 (d c ¯), and 1 D2(c u ¯) states respectively. We tentatively identify the DJ*(3000 )0 as the 1 3F4 (c u ¯ ) and favor the DJ(3000 )0 to be the 3 1S0 (c u ¯ ) although we do not rule out the 1 F3 and 1 F3' assignment. For the recently observed charm-strange mesons we identify the Ds1 *(2709 )±,Ds1 *(2860 )-,andDs3 *(2860 )-as the 2 3S1 (c s ¯), 1 3D1 (s c ¯), and 1 3D3 (s c ¯) states respectively and suggest that the Ds J(3044 )± is most likely the Ds 1(2 P1' ) or Ds 1(2 P1) state although it might be the Ds2 *(2 3P2 ) with the D K final state too small to be observed with current statistics. Based on the predicted properties of excited states, that they do not have too large a total width and that they have a reasonable branching ratio to simple final states, we suggest states that should be able to be found in the near future. We expect that the tables of properties summarizing our results will be useful for interpreting future observations of charm and charm-strange mesons.

  2. Latest Results on Orbitally Excited Strange Bottom Mesons with the CDF II Detector

    SciTech Connect

    Gorelov, Igor V.; /New Mexico U.

    2006-10-01

    The authors present the latest results on the spectroscopy of orbitally excited strange bottom mesons from {approx} 1 fb{sup -1} of CDF data. The measurements are performed with fully reconstructed B decays collected by the CDF II detector at {radical}s = 1.96 TeV in both the di-muon and the fully hadronic trigger paths.

  3. Exploring Strange Nonchaotic Attractors through Jacobian Elliptic Functions

    ERIC Educational Resources Information Center

    Garcia-Hoz, A. Martinez; Chacon, R.

    2011-01-01

    We demonstrate the effectiveness of Jacobian elliptic functions (JEFs) for inquiring into the reshaping effect of quasiperiodic forces in nonlinear nonautonomous systems exhibiting strange nonchaotic attractors (SNAs). Specifically, we characterize analytically and numerically some reshaping-induced transitions starting from SNAs in the context of…

  4. Strong decays of excited 1D charmed(-strange) mesons in the covariant oscillator quark model

    NASA Astrophysics Data System (ADS)

    Maeda, Tomohito; Yoshida, Kento; Yamada, Kenji; Ishida, Shin; Oda, Masuho

    2016-05-01

    Recently observed charmed mesons, D1* (2760), D3* (2760) and charmed-strange mesons, Ds1 * (2860), Ds3 * (2860), by BaBar and LHCb collaborations are considered to be plausible candidates for c q ¯ 13 DJ (q = u, d, s) states. We calculate the strong decays with one pion (kaon) emission of these states including well-established 1S and 1P charmed(-strange) mesons within the framework of the covariant oscillator quark model. The results obtained are compared with the experimental data and the typical nonrelativistic quark-model calculations. Concerning the results for 1S and 1P states, we find that, thanks to the relativistic effects of decay form factors, our model parameters take reasonable values, though our relativistic approach and the nonrelativistic quark model give similar decay widths in agreement with experiment. While the results obtained for 13 DJ=1,3 states are roughly consistent with the present data, they should be checked by the future precise measurement.

  5. Heavy-Quark Symmetry and the Electromagnetic Decays of Excited Charmed Strange Mesons

    SciTech Connect

    Thomas Mehen; Roxanne P. Springer

    2004-10-01

    Heavy-hadron chiral perturbation theory (HH{chi}PT) is applied to the decays of the even-parity charmed strange mesons, D{sub s0}(2317) and D{sub s1}(2460). Heavy-quark spin symmetry predicts the branching fractions for the three electromagnetic decays of these states to the ground states D{sub s} and D{sub s}* in terms of a single parameter. The resulting predictions for two of the branching fractions are significantly higher than current upper limits from the CLEO experiment. Leading corrections to the branching ratios from chiral loop diagrams and spin-symmetry violating operators in the HH{chi}PT Lagrangian can naturally account for this discrepancy. Finally the proposal that the D{sub s0}(2317) (D{sub s1}(2460)) is a hadronic bound state of a D (D*) meson and a kaon is considered. Leading order predictions for electromagnetic branching ratios in this molecular scenario are in very poor agreement with existing data.

  6. Newly observed D{sub sJ}(3040) and the radial excitations of P-wave charmed-strange mesons

    SciTech Connect

    Sun Zhifeng; Liu Xiang

    2009-10-01

    Inspired by the newly observed D{sub sJ}(3040){sup +} state, in this work we systemically study the two-body strong decays of P-wave charmed-strange mesons with the first radial excitation. Under the assignment of 1{sup +}(j{sup P}=(1/2){sup +}), i.e. the first radial excitation of D{sub s1}(2460){sup +}, we find that the width of D{sub sJ}(3040){sup +} is close to the lower limit of the BABAR measurement. This indicates that it is reasonable to interpret D{sub sJ}(3040){sup +} as the first radial excitation of D{sub s1}(2460){sup +}. Our calculation further predicts that 0{sup -}+1{sup -} channels, e.g., D{sup +}K*{sup 0}, D{sup 0}K*{sup +}, and D{sub s}{sup +}{phi}, are important for the search for D{sub sJ}(3040){sup +}. To help future experiments find the remaining three P-wave charmed-strange mesons with the first radial excitation, we present the predictions for the strong decays of these three P-wave charmed-strange mesons.

  7. Wavelet excited measurement of system transfer function.

    PubMed

    Olkkonen, H; Olkkonen, J T

    2007-02-01

    This article introduces a new method, which is referred to as the wavelet excitation method (WEM), for the measurement of the system transfer function. Instead of commonly used impulse or sine wave excitations, the method uses a sequential excitation by biorthogonal symmetric wavelets. The system transfer function is reconstructed from the output measurements. In the WEM the signals can be designed so that if N different excitation sequences are used and the excitation rate is f, the sampling rate of the analog-to-digital converter can be reduced to f/N. The WEM is especially advantageous in testing systems, where high quality impulse excitation cannot be applied. The WEM gave consistent results in transfer function measurements of various multistage amplifiers with the linear circuit analysis (SPICE) and the sine wave excitation methods. The WEM makes available new high speed sensor applications, where the sampling rate of the sensor may be considerably lower compared with the system bandwidth. PMID:17578145

  8. Strange Baryon Physics in Full Lattice QCD

    SciTech Connect

    Huey-Wen Lin

    2007-11-01

    Strange baryon spectra and form factors are key probes to study excited nuclear matter. The use of lattice QCD allows us to test the strength of the Standard Model by calculating strange baryon quantities from first principles.

  9. A Study of Excited Charm-Strange Baryons withEvidence for new Baryons Xi_c(3055)+ and Xi_c(3123)+

    SciTech Connect

    Collaboration, The BABAR; Aubert, B.

    2007-10-30

    We present a study of excited charm-strange baryon states produced in e{sup +}e{sup -} annihilations at or near a center-of-mass energy of 10.58 GeV, in a data sample with an integrated luminosity of 384 fb{sup -1} recorded with the BABAR detector at the PEP-II e+e storage rings at the Stanford Linear Accelerator Center. We study strong decays of charm-strange baryons to {Lambda}{sub c}{sup +}K{sub S}{sup 0}, {Lambda}{sub c}{sup +}K{sup -}, {Lambda}{sub c}{sup +}K{sup -}{pi}{sup +}, {Lambda}{sub c}{sup +}K{sub S}{sup 0}{pi}{sup -}, {Lambda}{sub c}{sup +}K{sub S}{sup 0}{pi}{sup -}{pi}{sup +}, {Lambda}{sub c}{sup +}K{sup -}{pi}{sup -}{pi}{sup +}. This study confirms the existence of the states {Xi}{sub c}(2980){sup +}, {Xi}{sub c}(3077){sup +}, and {Xi}{sub c}(3077){sup -}, with a more accurate determination of the {Xi}{sub c}(2980){sup +} mass and width. We also present evidence for two new states, {Xi}{sub c}(3055){sup +} and {Xi}{sub c}(3123){sup +}, decaying through the intermediate resonant modes {Sigma}{sub c}(2455){sup ++}K{sup -} and {Sigma}{sub c}(2520){sup ++}K{sup -}, respectively. For each of these baryons, we measure the yield in each final state, determine the statistical significance, and calculate the product of the production cross-section and branching fractions. We also measure the masses and widths of these excited charm-strange baryons.

  10. Strange stars

    NASA Technical Reports Server (NTRS)

    Alcock, Charles; Farhi, Edward; Olinto, Angela

    1986-01-01

    Strange matter, a form of quark matter that is postulated to be absolute stable, may be the true ground stage of the hadrons. If this hypothesis is correct, neutron stars may convert to 'strange stars'. The mass-radius relation for strange stars is very different from that of neutron stars; there is no minimum mass, and for mass of 1 solar mass or less, mass is proportional to the cube of the radius. For masses between 1 solar mass and 2 solar masses, the radii of strange stars are about 10 km, as for neutron stars. Strange stars may have an exposed quark surface, which is capable of radiating at rates greatly exceeding the Eddington limit, but has a low emissivity for X-ray photons. The stars may have a thin crust with the same composition as the preneutron drip outer layer of a conventional neutron star crust. Strange stars cool efficiently via neutrino emission.

  11. Study of natural spin-parity strange meson radial excitations in K/sup -/p. -->. K/sup -/. pi. /sup +/n at 11 GeV/c

    SciTech Connect

    Durkin, L.S.

    1980-12-01

    Results are presented from a high statistics study of the reaction K/sup -/p ..-->.. K/sup -/..pi../sup +/n at 11 GeV/c. This data was selected offline from an approx. 1000 event/..mu..b K/sup -/p experiment run on the Large Aperture Solenoid Spectrometer (LASS) at SLAC which triggered on essentially the total inelastic cross section. This K/sup -/..pi../sup +/n sample, after cuts, contained approx. 42,000 events in the K..pi.. invariant mass region from 0.65 GeV to 2.30 GeV, and absolute value t' < 0.2 GeV/sup 2/. A spherical harmonic angular moments analysis of this data is presented, as well as an energy independent partial wave analysis (PWA) of these angular moments. The nearly uniform acceptance characteristics of this data allowed a detailed analysis, which yielded information on natural spin-parity strange meson resonances in the K..pi.. invariant mass range from 0.65 GeV to 2.30 GeV. The well established K*(895), K*(1430), and K*(1780) are observed, and clear evidence is presented for a J/sup P/ = 4/sup +/ strange meson state at a mass of 2.08 GeV. The K/sup -/..pi../sup +/ elastic scattering partial waves extracted in this PWA show unambiguous evidence for a relatively narrow S wave resonance near 1.42 GeV in the K..pi.. invariant mass. This state is a confirmation of the 0/sup +/ K(1500) seen in previous PWA's. A new higher S wave resonance is clearly seen unambiguously near 1.90 GeV. Unambiguous evidence is presented for a relatively wide P wave resonance in the 1.70 GeV region.A second new P wave resonance also is seen in two of four ambiguous partial wave solutions in the 2.10 GeV region. These resonance states are discussed within the framework of a simple harmonic oscillator quark model. In particular three of the underlying resonances are discussed as possible natural spin-parity strange meson radial excitations.

  12. Fusion excitation functions involving transitional nuclei

    SciTech Connect

    Rehm, K.E.; Jiang, C.L.; Esbensen, H.

    1995-08-01

    Measurements of fusion excitation functions involving transitional nuclei {sup 78}Kr and {sup 100}Mo showed a different behavior at low energies, if compared to measurements with {sup 86}Kr and {sup 92}Mo. This points to a possible influence of nuclear structure on the fusion process. One way to characterize the structure of vibrational nuclei is via their restoring force parameters C{sub 2} which can be calculated from the energy of the lowest 2{sup +} state and the corresponding B(E2) value. A survey of the even-even nuclei between A = 28-150 shows strong variations in C{sub 2} values spanning two orders of magnitude. The lowest values for C{sub 2} are observed for {sup 78}Kr, {sup 104}Ru and {sup 124}Xe followed by {sup 74,76}Ge, {sup 74,76}Se, {sup 100}Mo and {sup 110}Pd. In order to learn more about the influence of {open_quotes}softness{close_quotes} on the sub-barrier fusion enhancement, we measured cross sections for evaporation residue production for the systems {sup 78}Kr + {sup 104}Ru and {sup 78}Kr + {sup 76}Ge with the gas-filled magnet technique. For both systems, fusion excitation functions involving the closed neutron shell nucleus {sup 86}Kr were measured previously. The data are presently being analyzed.

  13. Dynamics of strangeness production in heavy-ion collisions near threshold energies

    SciTech Connect

    Feng Zhaoqing; Jin Genming

    2010-11-15

    Within the framework of the improved isospin-dependent quantum molecular dynamics (ImIQMD) model, the dynamics of strangeness (K{sup 0,+}, {Lambda}, and {Sigma}{sup -,0,+}) production in heavy-ion collisions near threshold energies is investigated systematically, with the strange particles considered to be produced mainly by inelastic collisions of baryon-baryon and pion-baryon. Collisions in the region of suprasaturation densities of the dense baryonic matter formed in heavy-ion collisions dominate the yields of strangeness production. Total multiplicities as functions of incident energies and collision centralities are calculated with the Skyrme parameter SLy6. The excitation function of strangeness production is analyzed and also compared with the KaoS data for K{sup +} production in the reactions {sup 12}C+{sup 12}C and {sup 197}Au+{sup 197}Au.

  14. Ensemble density functional theory method correctly describes bond dissociation, excited state electron transfer, and double excitations

    SciTech Connect

    Filatov, Michael; Huix-Rotllant, Miquel; Burghardt, Irene

    2015-05-14

    State-averaged (SA) variants of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method, SA-REKS and state-interaction (SI)-SA-REKS, implement ensemble density functional theory for variationally obtaining excitation energies of molecular systems. In this work, the currently existing version of the SA-REKS method, which included only one excited state into the ensemble averaging, is extended by adding more excited states to the averaged energy functional. A general strategy for extension of the REKS-type methods to larger ensembles of ground and excited states is outlined and implemented in extended versions of the SA-REKS and SI-SA-REKS methods. The newly developed methods are tested in the calculation of several excited states of ground-state multi-reference systems, such as dissociating hydrogen molecule, and excited states of donor–acceptor molecular systems. For hydrogen molecule, the new method correctly reproduces the distance dependence of the lowest excited state energies and describes an avoided crossing between the doubly excited and singly excited states. For bithiophene–perylenediimide stacked complex, the SI-SA-REKS method correctly describes crossing between the locally excited state and the charge transfer excited state and yields vertical excitation energies in good agreement with the ab initio wavefunction methods.

  15. Strangeness Physics with CLAS at Jefferson Lab

    SciTech Connect

    Burkert, Volker

    2009-10-01

    A brief overview of strangeness physics with the CLAS detector at JLab is given, mainly covering the domain of nucleon resonances. Several excited states predicted by the symmetric constituent quark model may have signiffcant couplings to the K+ or K0 channels. I will discuss data that are relevant in the search for such states in the strangeness channel, and give an outlook on the future prospects of the N* program at JLab with electromagnetic probes.

  16. Strangeness in the Nucleon

    SciTech Connect

    Dahiya, Harleen; Gupta, Manmohan

    2007-10-03

    There are several different experimental indications, such as the {sigma}{sub {pi}}{sub N} term, strange spin polarization, strangeness contribution to the magnetic moment of the proton, ratio of strange and non strange quark flavor distributions which suggest that the nucleon contains a hidden strangeness component which is contradictory to the naive constituent quark model. Chiral constituent quark model with configuration mixing ({chi}CQM{sub config}) is known to provide a satisfactory explanation of the ''proton spin problem'' and related issues. In the present work, we have extended the model to carry out the calculations for the parameters pertaining to the strange quark content of the nucleon, for example, the strange spin polarization {delta}s, strange components of the weak axial vector form factors {delta}{sigma} and {delta}{sub 8} as well as F and D, strangeness magnetic moment of the proton {mu}{sub p}{sup s}, the strange quark content in the nucleon f{sub s} coming from the {sigma}{sub {pi}}{sub N} term, the ratios between strange and non-strange quarks (2s/u+d) and (2s/u-bar+d), contribution of strangeness to angular momentum sum rule etc. Our result demonstrates the broad consistency with the experimental observations as well as other theoretical considerations.

  17. Nuclear collective excitations: A relativistic density functional approach

    NASA Astrophysics Data System (ADS)

    Piekarewicz, J.

    2015-08-01

    Density functional theory provides the most promising, and likely unique, microscopic framework to describe nuclear systems ranging from finite nuclei to neutron stars. Properly optimized energy density functionals define a new paradigm in nuclear theory where predictive capability is possible and uncertainty quantification is demanded. Moreover, density functional theory offers a consistent approach to the linear response of the nuclear ground state. In this paper, we review the fundamental role played by nuclear collective modes in uncovering novel excitations and in guiding the optimization of the density functional. Indeed, without collective excitations the determination of the density functional remains incomplete. Without collective excitations, the equation of state of neutron-rich matter continues to be poorly constrained. We conclude with a discussion of some of the remaining challenges in this field and propose a path forward to address these challenges.

  18. Strange Quark Star Crusts

    SciTech Connect

    Steiner, Andrew W.

    2007-02-27

    If strange quark matter is absolutely stable, some neutron stars may be strange quark stars. Strange quark stars are usually assumed to have a simple liquid surface. We show that if the surface tension of droplets of quark matter in the vacuum is sufficiently small, droplets of quark matter on the surface of a strange quark star may form a solid crust on top of the strange quark star. This solid crust can significantly modify the predictions for the photon emission for the surface in an observable way.

  19. Charmed-strange mesons revisited: Mass spectra and strong decays

    NASA Astrophysics Data System (ADS)

    Song, Qin-Tao; Chen, Dian-Yong; Liu, Xiang; Matsuki, Takayuki

    2015-03-01

    Inspired by the present experimental status of charmed-strange mesons, we perform a systematic study of the charmed-strange meson family in which we calculate the mass spectra of the charmed-strange meson family by taking a screening effect into account in the Godfrey-Isgur model and investigate the corresponding strong decays via the quark pair creation model. These phenomenological analyses of charmed-strange mesons not only shed light on the features of the observed charmed-strange states, but also provide important information on future experimental search for the missing higher radial and orbital excitations in the charmed-strange meson family, which will be a valuable task in LHCb, the forthcoming Belle II, and PANDA.

  20. Excitations and benchmark ensemble density functional theory for two electrons

    SciTech Connect

    Pribram-Jones, Aurora; Burke, Kieron; Yang, Zeng-hui; Ullrich, Carsten A.; Trail, John R.; Needs, Richard J.

    2014-05-14

    A new method for extracting ensemble Kohn-Sham potentials from accurate excited state densities is applied to a variety of two-electron systems, exploring the behavior of exact ensemble density functional theory. The issue of separating the Hartree energy and the choice of degenerate eigenstates is explored. A new approximation, spin eigenstate Hartree-exchange, is derived. Exact conditions that are proven include the signs of the correlation energy components and the asymptotic behavior of the potential for small weights of the excited states. Many energy components are given as a function of the weights for two electrons in a one-dimensional flat box, in a box with a large barrier to create charge transfer excitations, in a three-dimensional harmonic well (Hooke's atom), and for the He atom singlet-triplet ensemble, singlet-triplet-singlet ensemble, and triplet bi-ensemble.

  1. Strangeness in Nucleon

    SciTech Connect

    Benaoum, Hachemi

    2008-04-01

    Results of the parity violating asymmetry APV for longitudinally polarized 3 GeV electrons from both hydrogen and helium cryogenic targets, at small scatteting angle thetalab~6 ° are presented. The asymmetry for hydrogen is a function of a linear combination of GEs and GMs, the strange quark contributions to the electric and magnetic form factors of the nucleon respectively, and that for 4He is a function solely of GEs. The combination of the two results therefore allows GEs and GMs to be separately determined.

  2. Strange Light Nuclei

    SciTech Connect

    Nakamura, Satoshi N.

    2014-04-01

    "Strange" means 1) unusual or surprising, especially in a way that is difficult to explain or understand or 2) having strangeness degree of freedom. Light nuclear systems with strangeness, light hypernuclei, are perfect playground to study baryon force which would be a bridge between well established nuclear force in low energy region and QCD, the first principle of the strong interaction. Overview of study of light hypernuclei is given and recent experimental findings are reviewed.

  3. The physics of strange matter

    SciTech Connect

    Olinto, A.V. |

    1991-12-01

    Strange matter may be the ground state of matter. We review the phenomenology and astrophysical implications of strange matter, and discuss the possible ways for testing the strange matter hypothesis.

  4. Proton-Proton Elastic Scattering Excitation Functions at Intermediate Energies

    SciTech Connect

    Bisplinghoff, J.; Daniel, R.; Diehl, O.; Engelhardt, H.; Ernst, J.; Eversheim, P.; Gro-Hardt, R.; Heider, S.; Heine, A.; Hinterberger, F.; Jahn, R.; Jeske, M.; Lahr, U.; Maschuw, R.; Mayer-Kuckuk, T.; Mosel, F.; Rohdje, H.; Rosendaal, D.; Ro, U.; Scheid, H.; Schulz-Rojahn, M.; Schwandt, F.; Schwarz, V.; Trelle, H.; Wiedmann, W.; Ziegler, R.; Albers, D.; Bollmann, R.; Bueer, K.; Dohrmann, F.; Gasthuber, M.; Greiff, J.; Gro, A.; Igelbrink, M.; Langkau, R.; Lindlein, J.; Mueller, M.; Muenstermann, M.; Schirm, N.; Scobel, W.; Wellinghausen, A.; Woller, K.; Cloth, P.; Gebel, R.; Maier, R.; Prasuhn, D.; von Rossen, P.; Sterzenbach, G.

    1997-03-01

    Excitation functions of proton-proton elastic scattering cross sections have been measured in narrow steps for projectile momenta p{sub p} (energies T{sub p}) from 1100 to 3300MeV/c (500 to 2500MeV) in the angular range 35{degree}{le}{Theta}{sub c.m.}{le}90{degree} with a detector providing {Delta}{Theta}{sub c.m.}{approx}1.4{degree} resolution. Measurements have been performed continuously during projectile acceleration in the cooler synchrotron COSY with an internal CH{sub 2} fiber target, taking particular care to monitor luminosity as a function of T{sub p}. The advantages of this experimental technique are demonstrated, and the excitation functions obtained are compared to existing cross section data. No evidence for narrow structures was found. {copyright} {ital 1997} {ital The American Physical Society}

  5. Dielectric Function and Electronic Excitations of Functionalized DNA Thin Films

    NASA Astrophysics Data System (ADS)

    Lee, Hosuk; Lee, Hosun; Lee, Jung Eun; Rha Lee, U.; Choi, Dong Hoon

    2010-06-01

    We measure the dielectric functions of organic-soluble, functionalized DNAs bearing functional moieties in the near-infrared, visible, and ultra-violet spectra by using spectroscopic ellipsometry. Natural double-stranded DNA is dissolved in water and reacted with carbazole-based trimethyl ammonium bromide, cetyltrimethylammonium bromide, and chalcone-terminated trimethyl ammonium bromide. The functional DNA products are all precipitated and filtered for washing and drying. We successfully prepare functionalized DNAs that are insoluble in water but soluble in organic solvents. The thin films are fabricated by using the spin coating technique after preparing solutions in either homogeneous or mixed organic solvents. We measure the ultraviolet-visible absorbance spectra of the films. The absorbance spectra show that the optical energy gaps of the functionalized DNAs change little even though the DNAs are connected to the complex molecules by electrostatic interaction. From the measured ellipsometric angles, we estimate the dielectric functions by using parametric optical constant model and layer model analysis. Depending on the nature of the attached complex molecules, the dielectric functions change, new optical structures develop below and above band gaps arising from the side molecules, and the optical energy gaps of the DNAs are altered slightly by weak coupling to the tethered complex molecules.

  6. Strangeness in the Meson Cloud Model

    SciTech Connect

    Signal, A. I.

    2010-07-27

    I review progress in calculating strange quark and antiquark distributions of the nucleon using the meson cloud model. This progress parallels that of the meson cloud model, which is now a useful theoretical basis for understanding symmetry breaking in nucleon parton distribution functions. I examine the breaking of symmetries involving strange quarks and antiquarks, including quark--antiquark symmetry in the sea, SU(3) flavour symmetry and SU(6) spin-flavour symmetry.

  7. Liquid-gas phase transition in nuclear matter including strangeness

    SciTech Connect

    Wang, P.; Leinweber, D.B.; Williams, A.G.; Thomas, A.W.

    2004-11-01

    We apply the chiral SU(3) quark mean field model to study the properties of strange hadronic matter at finite temperature. The liquid-gas phase transition is studied as a function of the strangeness fraction. The pressure of the system cannot remain constant during the phase transition, since there are two independent conserved charges (baryon and strangeness number). In a range of temperatures around 15 MeV (precise values depending on the model used) the equation of state exhibits multiple bifurcates. The difference in the strangeness fraction f{sub s} between the liquid and gas phases is small when they coexist. The critical temperature of strange matter turns out to be a nontrivial function of the strangeness fraction.

  8. Strange Nonchaotic Stars

    NASA Astrophysics Data System (ADS)

    Lindner, John F.; Kohar, Vivek; Kia, Behnam; Hippke, Michael; Learned, John G.; Ditto, William L.

    2015-02-01

    The unprecedented light curves of the Kepler space telescope document how the brightness of some stars pulsates at primary and secondary frequencies whose ratios are near the golden mean, the most irrational number. A nonlinear dynamical system driven by an irrational ratio of frequencies generically exhibits a strange but nonchaotic attractor. For Kepler's "golden" stars, we present evidence of the first observation of strange nonchaotic dynamics in nature outside the laboratory. This discovery could aid the classification and detailed modeling of variable stars.

  9. [Through strangeness to oneself].

    PubMed

    Sorgedrager, D B

    1993-11-01

    "Being strange" as opposed to "being oneself" is part of the thinking in all cultures. Belonging to a given culture is actually defined by ones identity and by "being oneself". Both concepts--"being oneself" or "being strange"--are rational and related constructs. Whatever they are confronted with, for most human beings it is self-evident to differentiate between subject and object, between "being oneself" or "being strange". This explains why thinking often occurs in opposites or polarities, as an either/or. All "being strange" has its origins in one's own self. "Being strange" becomes most obvious when persons, gestalt or cultures strongly deviate from one's own familiar situation. It is part of man's disposition to be cautious, suspicious of and at distance from everything considered strange and different. That explains his xenophobia feelings and actions. Behind this attitude we can always discover one's wish to preserve the familiar beliefs--combined with an uneasiness to give up one's thinking and behaviour that is proven and routine. It is only by reflecting on our own culture and our own inheritance that we have the possibility to come to terms with our own ethnic identity and foreign behavioral patterns. If we do not try to understand other cultures while keeping our own cultural identity, tensions and violent conflicts will inevitably result. PMID:8278564

  10. Band Excitation in Scanning Probe Microscopy: Recognition and Functional Imaging

    SciTech Connect

    Jesse, Stephen; Vasudevan, Dr. Rama; Collins, Liam; Strelcov, Evgheni; Okatan, Mahmut B; Belianinov, Alex; Baddorf, Arthur P; Proksch, Roger; Kalinin, Sergei V

    2014-01-01

    Field confinement at the junction between a biased scanning probe microscope s (SPM) tip and solid surface enables local probing of various bias-induced transformations such as polarization switching, ionic motion, or electrochemical reactions to name a few. The nanoscale size of the biased region is smaller or comparable to features like grain boundaries and dislocations, potentially allows for the study of kinetics and thermodynamics at the level of a single defect. In contrast to classical statistically averaged approaches, this allows one to link structure to functionality and deterministically decipher associated mesoscopic and atomistic mechanisms. Furthermore, this type of information can serve as a fingerprint of local material functionality, allowing for local recognition imaging. Here, current progress in multidimensional SPM techniques based on band-excitation time and voltage spectroscopies is illustrated, including discussions on data acquisition, dimensionality reduction, and visualization along with future challenges and opportunities for the field.

  11. Coupled cluster Green function: Model involving single and double excitations

    NASA Astrophysics Data System (ADS)

    Bhaskaran-Nair, Kiran; Kowalski, Karol; Shelton, William A.

    2016-04-01

    In this paper, we report on the development of a parallel implementation of the coupled-cluster (CC) Green function formulation (GFCC) employing single and double excitations in the cluster operator (GFCCSD). A key aspect of this work is the determination of the frequency dependent self-energy, Σ(ω). The detailed description of the underlying algorithm is provided, including approximations used that preserve the pole structure of the full GFCCSD method, thereby reducing the computational costs while maintaining an accurate character of methodology. Furthermore, for systems with strong local correlation, our formulation reveals a diagonally dominate block structure where as the non-local correlation increases, the block size increases proportionally. To demonstrate the accuracy of our approach, several examples including calculations of ionization potentials for benchmark systems are presented and compared against experiment.

  12. Coupled cluster Green function: Model involving single and double excitations.

    PubMed

    Bhaskaran-Nair, Kiran; Kowalski, Karol; Shelton, William A

    2016-04-14

    In this paper, we report on the development of a parallel implementation of the coupled-cluster (CC) Green function formulation (GFCC) employing single and double excitations in the cluster operator (GFCCSD). A key aspect of this work is the determination of the frequency dependent self-energy, Σ(ω). The detailed description of the underlying algorithm is provided, including approximations used that preserve the pole structure of the full GFCCSD method, thereby reducing the computational costs while maintaining an accurate character of methodology. Furthermore, for systems with strong local correlation, our formulation reveals a diagonally dominate block structure where as the non-local correlation increases, the block size increases proportionally. To demonstrate the accuracy of our approach, several examples including calculations of ionization potentials for benchmark systems are presented and compared against experiment. PMID:27083702

  13. Strangeness at SIS energies

    SciTech Connect

    Koch, Volker

    2005-09-28

    In this contribution the authors discuss the physics of strange hadrons in low energy ({approx_equal} 1-2 AGeV) heavy ion collision. In this energy range the relevant strange particle are the kaons and anti-kaons. The most interesting aspect concerning these particles are so called in-medium modifications. They will attempt to review the current status of understanding of these in medium modifications. In addition they briefly discuss other issues related with kaon production, such as the nuclear equation of state and chemical equilibrium.

  14. Strange nonchaotic stars.

    PubMed

    Lindner, John F; Kohar, Vivek; Kia, Behnam; Hippke, Michael; Learned, John G; Ditto, William L

    2015-02-01

    The unprecedented light curves of the Kepler space telescope document how the brightness of some stars pulsates at primary and secondary frequencies whose ratios are near the golden mean, the most irrational number. A nonlinear dynamical system driven by an irrational ratio of frequencies generically exhibits a strange but nonchaotic attractor. For Kepler's "golden" stars, we present evidence of the first observation of strange nonchaotic dynamics in nature outside the laboratory. This discovery could aid the classification and detailed modeling of variable stars. PMID:25699444

  15. Functional Assessment of Corticospinal System Excitability in Karate Athletes

    PubMed Central

    Moscatelli, Fiorenzo; Messina, Giovanni; Valenzano, Anna; Monda, Vincenzo; Viggiano, Andrea; Messina, Antonietta; Petito, Annamaria; Triggiani, Antonio Ivano; Ciliberti, Michela Anna Pia; Monda, Marcellino; Capranica, Laura; Cibelli, Giuseppe

    2016-01-01

    Objectives To investigate the involvement of the primary motor cortex (M1) in the coordination performance of karate athletes through transcranial magnetic stimulation (TMS). Methods Thirteen right-handed male karate athletes (25.0±5.0 years) and 13 matched non-athlete controls (26.7±6.2 years) were enrolled. A single-pulse TMS was applied using a figure-eight coil stimulator. Resting motor threshold (rMT) was determined. Surface electromyography was recorded from the first dorsal interosseous muscle. Motor evoked potential (MEP) latencies and amplitudes at rMT, 110%, and 120% of rMT were considered. Functional assessment of the coordination performance was assessed by in-phase (IP) and anti-phase (AP) homolateral hand and foot coordination tasks performed at 80, 120, and 180 bpm. Results Compared to controls, athletes showed lower rMT (p<0.01), shorter MEP latency (p<0.01) and higher MEP amplitude (p<0.01), with a significant correlation (r = 0.50, p<0.01) between rMT and MEP latency. Coordination decreased with increasing velocity, and better IP performances emerged compared to AP ones (p<0.001). In general, a high correlation between rMT and coordination tasks was found for both IP and AP conditions. Conclusion With respect to controls, karate athletes present a higher corticospinal excitability indicating the presence of an activity-dependent alteration in the balance and interactions between inhibitory and facilitatory circuits determining the final output from the M1. Furthermore, the high correlation between corticospinal excitability and coordination performance could support sport-specific neurophysiological arrangements. PMID:27218465

  16. Two alternative versions of strangeness

    PubMed Central

    Nishijima, Kazuhikoa

    2008-01-01

    The concept of strangeness emerged from the low energy phenomenology before the entry of quarks in particle physics. The connection between strangeness and isospin is rather accidental and loose and we recognize later that the definition of strangeness is model-dependent. Indeed, in Gell-Mann’s triplet quark model we realize that there is a simple alternative representation of strangeness. When the concept of generations is incorporated into the quark model we find that only the second alternative version of strangeness remains meaningful, whereas the original one does no longer keep its significance. PMID:18997448

  17. Excitation energies of molecules within time-independent density functional theory

    SciTech Connect

    Hemanadhan, M. Harbola, Manoj K.

    2014-04-24

    Recently proposed exchange energy functional for excited-states is tested for obtaining excitation energies of diatomic molecules. The functional is the ground-state counterpart of the local-density approximation, the modified local spin density (MLSD). The MLSD functional is tested for the N{sub 2} and CO diatomic molecules. The excitation energy obtained with the MLSD functional for the N{sub 2} molecule is in close vicinity to that obtained from the exact exchange orbital functional, Krieger, Li and Iafrate (KLI). For the CO molecule, the departure in excitation energy is observed and is due to the overcorrection of self-interaction.

  18. Strange Nonchaotic Stars

    NASA Astrophysics Data System (ADS)

    Lindner, John F.; Kohar, Vivek; Kia, Behnam; Hippke, Michael; Learned, John G.; Ditto, William L.

    2015-08-01

    Exploiting the unprecedented capabilities of the planet-hunting Kepler space telescope, which stared at 150 000 stars for four years, we discuss recent evidence that certain stars dim and brighten in complex patterns with fractal features. Such stars pulsate at primary and secondary frequencies whose ratios are near the famous golden mean, the most irrational number. A nonlinear system driven by an irrational ratio of frequencies is generically attracted toward a “strange” behavior that is geometrically fractal without displaying the “butterfly effect” of chaos. Strange nonchaotic attractors have been observed in laboratory experiments and have been hypothesized to describe the electrochemical activity of the brain, but a bluish white star 16 000 light years from Earth in the constellation Lyra may manifest, in the scale-free distribution of its minor frequency components, the first strange nonchaotic attractor observed in the wild. The recognition of stellar strange nonchaotic dynamics may improve the classification of these stars and refine the physical modeling of their interiors. We also discuss nonlinear analysis of other RR Lyrae stars in Kepler field of view and discuss some toy models for modeling these stars.References: 1) Hippke, Michael, et al. "Pulsation period variations in the RRc Lyrae star KIC 5520878." The Astrophysical Journal 798.1 (2015): 42.2) Lindner, John F., et al. "Strange nonchaotic stars." Phys. Rev. Lett. 114, 054101 (2015)

  19. Multiply Strange Nuclear Systems

    NASA Astrophysics Data System (ADS)

    Schaffner, J.; Dover, C. B.; Gal, A.; Greiner, C.; Millener, D. J.; Stocker, H.

    1994-10-01

    We investigate the stability of multiply strange baryonic systems, in the context of a mean field approach obtained from an underlying set of phenomenological meson-baryon interactions. The coupling parameters which determine the conventional σ + ω mean fields (Hartree potentials) seen by various baryon species (N, Λ, Ξ) in the many-body system are constrained by reproducing the trend of observed binding energies of single particle (N, Λ, Ξ) states, as well as the energy per particle and density of non-strange nuclear matter. We also consider additional scalar (σ*) and vector (φ) fields which couple strongly to strange baryons. The couplings of these fields are adjusted to produce strong hyperon-hyperon interactions, as suggested by the data on ΛΛ hypernuclei. Extrapolating this approach to systems of large strangeness S, we find a broad class of objects composed of neutrons, protons, Λ‧s and Ξ‧s, which are stable against strong decay. In these systems, the presence of filled Λ orbitals blocks the strong decay ΞN → ΛΛ, leading to a strangeness fraction fs = |S|/A ≍1, density ρ ≍ (2 - 3) ρ0, and charge fraction fq in the range - 0.1 strange quark matter ("stranglets"), but with a low binding energy per particle EB/A ≍ -10 to -20 MeV. We compare with an approximate mass formula which qualitatively describes the results of the mean field calculations. Such weakly bound multi-strange objects can be stable for very large A, unlike ordinary nuclei, since the Coulomb repulsion generated by the protons is largely cancelled by the presence of a comparable number of Ξ‧s, leading to a small net charge (positive or negative) of order A1/3. We comment on the weak decays of such subjects and the possibility of their production in relativistic heavy ion collisions.

  20. Some light-ion excitation-function measurements on titanium, yttrium, and europium, and associated results

    SciTech Connect

    West, H.I. Jr.; Lanier, R.G.; Mustafa, M.G.; Nuckolls, R.M.; Nagle, R.J.; O`Brien, H.; Frehaut, J.; Adam, A.; Philis, C.

    1993-11-01

    This report discusses: Fabrication of Plastic-Matrix-Encapsulated Accelerator Targets and Their Use in Measuring Nuclear Excitation Functions; Correcting Excitation Function Data in the Low Energy Region for Finite Thickness of the Target Foils, Including Effects of Straggling; Excitation Functions for the Nuclear Reactions on Titanium Leading to the Production {sup 48}V, {sup 44}Sc and {sup 47}Sc by Proton, Deuteron and Triton Irradiations at 0--35 MeV; Some Excitation Functions of Proton and Deuteron Induced Reactions on {sup 89}Y; Measurements of the Excitation Functions of the Isobaric Chain {sup 87}Y, {sup 87}Y{sup m}, {sup 87}Y{sup g} and {sup 87}Sr{sup m}; Levels in {sup 87}Y Observed in the Decay of {sup 87}Zr; and Nuclear Reaction Excitation Functions from the Irradiation of {sup 151,153}Eu with Protons And deuterons up to 35 MeV.

  1. Strange stars, strange dwarfs, and planetary-like strange-matter objects

    SciTech Connect

    Weber, F.; Schaab, C.; Weigel, M.K.; Glendenning, N.K.

    1995-05-01

    This paper gives an overview of the properties of all possible equilibrium sequences of compact strange-matter stars with nuclear crusts, which range from strange stars to strange dwarfs. In contrast to their non-strange counterparts--neutron stars and white dwarfs--their properties are determined by two (rather than one) parameters, the central star density and the density at the base of the nuclear crust. This leads to stellar strange-matter configurations whose properties are much more complex than those of the conventional sequence. As an example, two generically different categories of stable strange dwarfs are found, which could be the observed white dwarfs. Furthermore the authors find very-low-mass strange stellar objects, with masses as small as those of Jupiter or even lighter planets. Such objects, if abundant enough, should be seen by the presently performed gravitational microlensing searches.

  2. STAR results on strangeness production in beam energy scan program

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoping

    2016-01-01

    We present the recent STAR results on the production of strange hadrons (K0s, ϕ, Λ, Ξ and Ω) in √sNN= 7.7 — 39 GeV Au+Au collisions in the RHIC beam energy scan program. We investigate the strangeness enhancement and strangeness equilibration as a function of beam energy and system size at RHIC. Nuclear modification factors and particle ratios will be highlighted. Implications on partonic vs. hadronic dynamics as a function of the beam energy will be discussed.

  3. Excitation Control: Balancing PSD-95 Function at the Synapse

    PubMed Central

    Keith, Dove; El-Husseini, Alaa

    2008-01-01

    Excitability of individual neurons dictates the overall excitation in specific brain circuits. This process is thought to be regulated by molecules that regulate synapse number, morphology and strength. Neuronal excitation is also influenced by the amounts of neurotransmitter receptors and signaling molecules retained at particular synaptic sites. Recent studies revealed a key role for PSD-95, a scaffolding molecule enriched at glutamatergic synapses, in modulation of clustering of several neurotransmitter receptors, adhesion molecules, ion channels, cytoskeletal elements and signaling molecules at postsynaptic sites. In this review we will highlight mechanisms that control targeting of PSD-95 at the synapse, and discuss how this molecule influences the retention and clustering of diverse synaptic proteins to regulate synaptic structure and strength. We will also discuss how PSD-95 may maintain a balance between excitation and inhibition in the brain and how alterations in this balance may contribute to neuropsychiatric disorders. PMID:18946537

  4. Is There a Linear Building Transfer Function for Small Excitation?

    NASA Astrophysics Data System (ADS)

    Clinton, J. F.; Heaton, T. H.

    2003-12-01

    In the absence of actual building accelerometer data, the linear response of a structure to strong ground motion is estimated by the convolution of the dynamic response of the structure with an input ground motion. The input motion is usually provided by a local `reference' station record. In this study, we look at whether actual recorded ground motion at two instrumented buildings with well studied dynamic properties can be satisfactorily modeled using a local ground station. All stations record continuous 24-bit data streams on the CISN network, so analysis of a variety of weak earthquake motions, as well as ambient noise, is possible. Our buildings are the 9-story reinforced concrete Millikan Library (CISN Station MIK) and the 3-story braced steel frame Broad Center (CBC), both on the Caltech Campus. Motions recorded on their upper floors are compared with motions from ground stations located in the basement of a lightweight wood-frame house (GSA), and in a subsurface vault (CRP). All stations are within 200m of each other. Recent work using the new continuous datastream indicates that the natural frequencies of these structures can vary by up to 5% during normal ambient conditions, due to such factors as changing building usage, diurnal temperature variation, and wind/rainfall events. These shifts can be sudden, and models of building motions are sensitive to these previously un-documented changes. Further, during stronger motions, such as forced vibration testing, and minor earthquake shaking, natural frequencies are shown to drop by up to 10% (2003 M5.4 Big Bear Earthquake, Δ = 119km), with near-instantaneous recovery once the excitation is over. Moderate earthquakes can temporarily reduce frequencies by up to 30% with no apparent structural damage (1971 M6.6 San Fernando Earthquake, Δ = 31km). Post-event permanent reductions of about 10% have been observed. The ability to monitor these evolving dynamic characteristics makes a re-evaluation of the

  5. Possible resolution of the strange quark polarization puzzle?

    NASA Astrophysics Data System (ADS)

    Leader, Elliot; Sidorov, Alexander V.; Stamenov, Dimiter B.

    2011-07-01

    The strange quark polarization puzzle, i.e. the contradiction between the negative polarized strange quark density obtained from analyses of inclusive deep inelastic scattering data and the positive values obtained from combined analyses of inclusive and semi-inclusive deep inelastic scattering data using de Florian, Sassot, Stratmann fragmentation functions, is discussed. To this end the results of a new combined next-to-leading order QCD analysis of the polarized inclusive and semi-inclusive deep inelastic scattering data, using the Hirai, Kumano, Nagai, Sudoh (HKNS) fragmentation functions, are presented. It is demonstrated that the polarized strange quark density is very sensitive to the kaon fragmentation functions, and if the set of HKNS fragmentation functions is used, the polarized strange quark density obtained from the combined analysis turns out to be negative and well consistent with values obtained from the pure deep inelastic scattering analyses.

  6. Validation of local hybrid functionals for TDDFT calculations of electronic excitation energies

    NASA Astrophysics Data System (ADS)

    Maier, Toni M.; Bahmann, Hilke; Arbuznikov, Alexei V.; Kaupp, Martin

    2016-02-01

    The first systematic evaluation of local hybrid functionals for the calculation of electronic excitation energies within linear-response time-dependent density functional theory (TDDFT) is reported. Using our recent efficient semi-numerical TDDFT implementation [T. M. Maier et al., J. Chem. Theory Comput. 11, 4226 (2015)], four simple, thermochemically optimized one-parameter local hybrid functionals based on local spin-density exchange are evaluated against a database of singlet and triplet valence excitations of organic molecules, and against a mixed database including also Rydberg, intramolecular charge-transfer (CT) and core excitations. The four local hybrids exhibit comparable performance to standard global or range-separated hybrid functionals for common singlet valence excitations, but several local hybrids outperform all other functionals tested for the triplet excitations of the first test set, as well as for relative energies of excited states. Evaluation for the combined second test set shows that local hybrids can also provide excellent Rydberg and core excitations, in the latter case rivaling specialized functionals optimized specifically for such excitations. This good performance of local hybrids for different excitation types could be traced to relatively large exact-exchange (EXX) admixtures in a spatial region intermediate between valence and asymptotics, as well as close to the nucleus, and lower EXX admixtures in the valence region. In contrast, the tested local hybrids cannot compete with the best range-separated hybrids for intra- and intermolecular CT excitation energies. Possible directions for improvement in the latter category are discussed. As the used efficient TDDFT implementation requires essentially the same computational effort for global and local hybrids, applications of local hybrid functionals to excited-state problems appear promising in a wide range of fields. Influences of current-density dependence of local kinetic

  7. Strange skyrmion molecules

    NASA Astrophysics Data System (ADS)

    Kopeliovich, Vladimir B.; Stern, Boris E.

    1997-05-01

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

  8. 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.

  9. Dissociative excitation of the N(+)(5S) state by electron impact on N2 - Excitation function and quenching

    NASA Technical Reports Server (NTRS)

    Erdman, P. W.; Zipf, E. C.

    1986-01-01

    Metastable N(+)(5S) ions were produced in the laboratory by dissociative excitation of N2 with energetic electrons. The resulting radiative decay of the N(+)(5S) state was observed with sufficient resolution to completely resolve the doublet from the nearby N2 molecular radiation. The excitation function was measured from threshold to 500 eV. The cross section peaks at a high electron energy and also exhibits a high threshold energy both of which are typical of dissociative excitation-ionization processes. This finding complicates the explanation of electron impact on N2 as the mechanism for the source of the 2145 A 'auroral mystery feature' by further increasing the required peak cross section. It is suggested that the apparent N(+)(5S) quenching in auroras may be an artifact due to the softening of the electron energy spectrum in the auroral E region.

  10. Strange stars at finite temperature

    NASA Astrophysics Data System (ADS)

    Ray, Subharthi; Bagchi, Manjari; Dey, Jishnu; Dey, Mira

    2006-03-01

    We calculate strange star properties, using large Nc approximation with built-in chiral symmetry restoration (CSM). We used a relativistic Hartree Fock meanfield approximation method, using a modi.ed Richardson potential with two scale parameters Λ and Λ', to find a new set of equation of state (EOS) for strange quark matter. We take the effect of temperature (T) on gluon mass, in addition to the usual density dependence, and find that the transition T from hadronic matter to strange matter is 80 MeV. Therefore formation of strange stars may be the only signal for formation of QGP with asymptotic freedom (AF) and CSM.

  11. Exact strangeness conservation and particle production

    NASA Astrophysics Data System (ADS)

    Cleymans, J.; Redlich, K.; Suhonen, E.

    The production of strange particles is studied in terms of a statistical formalism requiring strangeness to be exactly conserved while baryon number is treated grand canonically using a chemical potential. The gas is considered to be in thermal and chemical equilibrium and to have zero overall strangeness. All particles and resonances having masses up to approximately 2 GeV and strangeness up to plus or minus 3 are included. General formulas for different particle multiplicities in terms of infinite series of modified Bessel functions are derived. In contrast to the integral representation of particle numbers in the canonical ensemble, results can be easily handled numerically since the series converge very rapidly. As an illustration, the above formalism is applied to the description of particle production in proton-proton, proton-nucleus and nucleus-nucleus collisions. In particular the K/pi ratio shows a strong dependence on the interaction volume on the system while, in contrast, the antiLambda/Lambda ratio is almost independent of the volume. These results are in qualitative agreement with experimental data.

  12. Is the Strange Situation Too Strange for Japanese Infants?

    ERIC Educational Resources Information Center

    Ujiie, Tastuo

    The applicability of the Strange Situation procedure and the ABC typology for Japanese infants is discussed by examining data from studies in which the Strange Situation procedure was performed with Japanese infants. Findings of a study conducted in Sapporo, Japan, are discussed and their implications are pointed out. The discussion concludes that…

  13. Strangeness of the nucleon from lattice QCD

    NASA Astrophysics Data System (ADS)

    Alexandrou, Constantia; Constantinou, Martha; Dinter, Simon; Drach, Vincent; Hadjiyiannakou, Kyriakos; Jansen, Karl; Koutsou, Giannis; Vaquero, Alejandro; ETM Collaboration

    2015-05-01

    We present a nonperturbative calculation of the strangeness of the nucleon yN within the framework of lattice QCD. This observable is known to be an important cornerstone to interpret results from direct dark matter detection experiments. We perform a lattice computation for yN with an analysis of systematic effects originating from discretization, finite size, chiral extrapolation and excited state effects leading to the value of yN=0.173 (50 ) . The rather large uncertainty of this value of yN is dominated by systematic uncertainties which we are able to quantify in this work.

  14. Excited-state properties and physiological functions of biological polyenes: the triplet-excited region of retinoids and carotenoids

    NASA Astrophysics Data System (ADS)

    Koyama, Y.; Mukai, Yumiko; Kuki, Michitaka

    1993-06-01

    Both experimental and theoretical results which indicate the presence of the triplet-excited region in retinoids and carotenoids are reviewed. The triplet- excited region is defined as a region where changes in the bond order take place, upon triplet excitation, toward its inversion, i.e., a double bond becomes more signal bond-like and a single bond becomes more double bond-like. (1) It has a span of approximately six conjugated double bonds, (2) it is localized in the central part of a conjugated chain, and (3) it triggers `cis' to `trans' isomerization in the T1 state. The experimental and theoretical results include: (1) the T1 Raman spectra of all-trans-retinal and its homologues; (2) the T1-state isomerization of isomeric retinal; (3) the T1-state isomerization of isomeric (beta) -carotene; (4) the PPP-SD-CI calculations of the bond orders of the carbon-carbon bonds in a set of model polyenes; and (5) the normal-coordinate analysis of the T1 Raman lines of undeuterated and deuterated all-trans-retinal. Finally, (6) the biological implication of 'the triplet-excited region' is discussed in relation to the photo-protective function of a 15-cis carotenoid bound to the bacterial photoreaction center.

  15. Strange experiments at the AGS

    SciTech Connect

    Chrien, R.

    1990-01-01

    The purpose of this review is to report recent progress in nuclear experiments involving strangeness which have been carried out at the Brookhaven Alternating Gradient Synchrotron over the past three years. These recent developments are noted in three areas: few body systems and dibaryons; strange probes of the nucleus; and associated production of hypernuclei. 9 refs., 3 figs.

  16. Electroproduction of Strange Nuclei

    SciTech Connect

    E.V. Hungerford

    2002-06-01

    The advent of high-energy, CW-beams of electrons now allows electro-production and precision studies of nuclei containing hyperons. Previously, the injection of strangeness into a nucleus was accomplished using secondary beams of mesons, where beam quality and target thickness limited the missing mass resolution. We review here the theoretical description of the (e, e'K+) reaction mechanism, and discuss the first experiment demonstrating that this reaction can be used to precisely study the spectra of light hypernuclei. Future experiments based on similar techniques, are expected to attain even better resolutions and rates.

  17. Memory matrix theory of magnetotransport in strange metals

    NASA Astrophysics Data System (ADS)

    Lucas, Andrew; Sachdev, Subir

    2015-05-01

    We model strange metals as quantum liquids without quasiparticle excitations, but with slow momentum relaxation and with slow diffusive dynamics of a conserved charge and energy. General expressions are obtained for electrical, thermal, and thermoelectric transport in the presence of an applied magnetic field using the memory matrix formalism. In the appropriate limits, our expressions agree with previous hydrodynamic and holographic results. We discuss the relationship of such results to thermoelectric and Hall transport measurements in the strange-metal phase of the hole-doped cuprates.

  18. ``Towards Strange Metallic Holography'

    SciTech Connect

    Hartnoll, Sean A.; Polchinski, Joseph; Silverstein, Eva; Tong, David; /Cambridge U., DAMTP /Santa Barbara, KITP /UC, Santa Barbara

    2010-08-26

    We initiate a holographic model building approach to 'strange metallic' phenomenology. Our model couples a neutral Lifshitz-invariant quantum critical theory, dual to a bulk gravitational background, to a finite density of gapped probe charge carriers, dually described by D-branes. In the physical regime of temperature much lower than the charge density and gap, we exhibit anomalous scalings of the temperature and frequency dependent conductivity. Choosing the dynamical critical exponent z appropriately we can match the non-Fermi liquid scalings, such as linear resistivity, observed in strange metal regimes. As part of our investigation we outline three distinct string theory realizations of Lifshitz geometries: from F theory, from polarized branes, and from a gravitating charged Fermi gas. We also identify general features of renormalization group flow in Lifshitz theories, such as the appearance of relevant charge-charge interactions when z {ge} 2. We outline a program to extend this model building approach to other anomalous observables of interest such as the Hall conductivity.

  19. The strange flight behaviour of slowly spinning soccer balls

    NASA Astrophysics Data System (ADS)

    Mizota, Taketo; Kurogi, Kouhei; Ohya, Yuji; Okajima, Atsushi; Naruo, Takeshi; Kawamura, Yoshiyuki

    2013-05-01

    The strange three-dimensional flight behaviour of slowly spinning soccer balls is one of the most interesting and unknown phenomenon associated with the trajectories of sports balls. Many spectators have experienced numerous exciting and emotional instances while observing the curious flight behaviour of these balls. We examine the aerodynamic mechanisms of erratic ball behaviours through real flight observations, unsteady force measurements and flow pattern visualisations. The strange behaviour is elucidated by the relationship between the unsteady forces on the ball and the wake flow. The irregular changes in position for twin longitudinal vortices have already been discovered in the supercritical Reynolds number region of a sphere with a smooth surface. This finding is applicable to the strange behaviour of the flight of soccer balls with this supercritical flow. The players, spectators, and television viewers will gain greater insight into the effects of soccer ball flights.

  20. The strange flight behaviour of slowly spinning soccer balls

    PubMed Central

    Mizota, Taketo; Kurogi, Kouhei; Ohya, Yuji; Okajima, Atsushi; Naruo, Takeshi; Kawamura, Yoshiyuki

    2013-01-01

    The strange three-dimensional flight behaviour of slowly spinning soccer balls is one of the most interesting and unknown phenomenon associated with the trajectories of sports balls. Many spectators have experienced numerous exciting and emotional instances while observing the curious flight behaviour of these balls. We examine the aerodynamic mechanisms of erratic ball behaviours through real flight observations, unsteady force measurements and flow pattern visualisations. The strange behaviour is elucidated by the relationship between the unsteady forces on the ball and the wake flow. The irregular changes in position for twin longitudinal vortices have already been discovered in the supercritical Reynolds number region of a sphere with a smooth surface. This finding is applicable to the strange behaviour of the flight of soccer balls with this supercritical flow. The players, spectators, and television viewers will gain greater insight into the effects of soccer ball flights. PMID:23695000

  1. Self-Consistent Optimization of Excited States within Density-Functional Tight-Binding.

    PubMed

    Kowalczyk, Tim; Le, Khoa; Irle, Stephan

    2016-01-12

    We present an implementation of energies and gradients for the ΔDFTB method, an analogue of Δ-self-consistent-field density functional theory (ΔSCF) within density-functional tight-binding, for the lowest singlet excited state of closed-shell molecules. Benchmarks of ΔDFTB excitation energies, optimized geometries, Stokes shifts, and vibrational frequencies reveal that ΔDFTB provides a qualitatively correct description of changes in molecular geometries and vibrational frequencies due to excited-state relaxation. The accuracy of ΔDFTB Stokes shifts is comparable to that of ΔSCF-DFT, and ΔDFTB performs similarly to ΔSCF with the PBE functional for vertical excitation energies of larger chromophores where the need for efficient excited-state methods is most urgent. We provide some justification for the use of an excited-state reference density in the DFTB expansion of the electronic energy and demonstrate that ΔDFTB preserves many of the properties of its parent ΔSCF approach. This implementation fills an important gap in the extended framework of DFTB, where access to excited states has been limited to the time-dependent linear-response approach, and affords access to rapid exploration of a valuable class of excited-state potential energy surfaces. PMID:26587877

  2. Converting neutron stars into strange stars

    NASA Technical Reports Server (NTRS)

    Olinto, A. V.

    1991-01-01

    If strange matter is formed in the interior of a neutron star, it will convert the entire neutron star into a strange star. The proposed mechanisms are reviewed for strange matter seeding and the possible strange matter contamination of neutron star progenitors. The conversion process that follows seeding and the recent calculations of the conversion timescale are discussed.

  3. Functional patterned multiphoton excitation deep inside scattering tissue

    NASA Astrophysics Data System (ADS)

    Papagiakoumou, Eirini; Bègue, Aurélien; Leshem, Ben; Schwartz, Osip; Stell, Brandon M.; Bradley, Jonathan; Oron, Dan; Emiliani, Valentina

    2013-04-01

    Stochastic distortion of light beams in scattering samples makes in-depth photoexcitation in brain tissue a major challenge. A common solution for overcoming scattering involves adaptive pre-compensation of the unknown distortion. However, this requires long iterative searches for sample-specific optimized corrections, which is a problem when applied to optical neurostimulation where typical timescales in the system are in the millisecond range. Thus, photoexcitation in scattering media that is independent of the properties of a specific sample would be an ideal solution. Here, we show that temporally focused two-photon excitation with generalized phase contrast enables photoexcitation of arbitrary spatial patterns within turbid tissues with remarkable robustness to scattering. We demonstrate three-dimensional confinement of tailored photoexcitation patterns >200 µm in depth, both in numerical simulations and through brain slices combined with patch-clamp recording of photoactivated channelrhodopsin-2.

  4. Electrically charged strange quark stars

    SciTech Connect

    Negreiros, Rodrigo Picanco; Weber, Fridolin; Malheiro, Manuel; Usov, Vladimir

    2009-10-15

    The possible existence of compact stars made of absolutely stable strange quark matter--referred to as strange stars--was pointed out by Witten almost a quarter of a century ago. One of the most amazing features of such objects concerns the possible existence of ultrastrong electric fields on their surfaces, which, for ordinary strange matter, is around 10{sup 18} V/cm. If strange matter forms a color superconductor, as expected for such matter, the strength of the electric field may increase to values that exceed 10{sup 19} V/cm. The energy density associated with such huge electric fields is on the same order of magnitude as the energy density of strange matter itself, which, as shown in this paper, alters the masses and radii of strange quark stars at the 15% and 5% levels, respectively. Such mass increases facilitate the interpretation of massive compact stars, with masses of around 2M{sub {center_dot}}, as strange quark stars.

  5. Core and valence excitations in resonant X-ray spectroscopy using restricted excitation window time-dependent density functional theory

    PubMed Central

    Zhang, Yu; Biggs, Jason D.; Healion, Daniel; Govind, Niranjan; Mukamel, Shaul

    2012-01-01

    We report simulations of X-ray absorption near edge structure (XANES), resonant inelastic X-ray scattering (RIXS) and 1D stimulated X-ray Raman spectroscopy (SXRS) signals of cysteine at the oxygen, nitrogen, and sulfur K and \\documentclass[12pt]{minimal}\\begin{document}$\\textrm {L}_{2,3}$\\end{document}L2,3 edges. Comparison of the simulated XANES signals with experiment shows that the restricted window time-dependent density functional theory is more accurate and computationally less expensive than the static exchange method. Simulated RIXS and 1D SXRS signals give some insights into the correlation of different excitations in the molecule. PMID:23181305

  6. Core and Valence Excitations in Resonant X-ray Spectroscopy using Restricted Excitation Window Time-dependent Density Functional Theory

    SciTech Connect

    Zhang, Yu; Biggs, Jason D.; Healion, Daniel; Govind, Niranjan; Mukamel, Shaul

    2012-11-21

    We report simulations of X-ray absorption near edge structure (XANES), resonant inelastic X-ray scattering (RIXS) and 1D stimulated X-ray Raman spectroscopy (SXRS) signals of cysteine at the oxygen, nitrogen and sulfur K and L2,3 edges. The simulated XANES signals from the restricted window time-dependent density functional theory (REW-TDDFT) and the static exchange (STEX) method are compared with experiments, showing that REW-TDDFT is more accurate and computationally less expensive than STEX. Simulated RIXS and 1D SXRS signals from REW-TDDFT give some insights on the correlation of different excitations in the molecule.

  7. Magnetic Field of Strange Dwarfs

    NASA Astrophysics Data System (ADS)

    Baghdasaryan, D. S.

    2016-03-01

    The generation of a magnetic field in a strange quark star owing to differential rotation of the superfluid and superconducting quark core relative to the normal electron-nuclear crust of the star is examined. The maximum possible magnetic field on the surface is estimated for various models of strange dwarfs. Depending on the configuration parameters, i.e., the mass M and radius R of the star, a range of 103-105 G is found. These values of the magnetic field may be an additional condition for identification of strange dwarfs among the extensive class of observed white dwarfs.

  8. Strange perspectives at FAIR

    NASA Astrophysics Data System (ADS)

    Steinheimer, J.; Sturm, C.; Schramm, S.; Stöcker, H.

    2010-09-01

    Adjacent to the existing accelerator complex of the GSI Helmholtz Centre for Heavy Ion Research at Darmstadt, Germany, the Facility for Antiproton and Ion Research (FAIR) substantially expands research goals and technical possibilities. It will provide worldwide unique accelerator and experimental facilities allowing for a large variety of unprecedented fore-front research in hadron, nuclear and atomic physics as well as applied sciences which will be described briefly in this paper. The start version of FAIR, the so-called Modularized Start Version, will deliver first beams in 2017/2018. As an example the paper presents research efforts on strangeness at FAIR using heavy ion collisions, exotic nuclei from fragmentation and antiprotons to tackle various topics in this area. In particular hypernuclei and metastable exotic multi-hypernuclear objects will be investigated.

  9. Comparison of the hydrological excitation functions HAM of polar motion for the period 1980.0-2007.0

    NASA Astrophysics Data System (ADS)

    Nastula, J.; Pasnicka, M.; Kolaczek, B.

    2011-10-01

    In this study we compared contributions of polar motion excitation determined from hydrological models and harmonic coefficients of the Earth gravity field obtained from Gravity Recovery and Climate Experiment (GRACE). Hydrological excitation function (hydrological angular momentum - HAM) has been estimated from models of global hydrology, based on the observed distribution of surface water, snow, ice and soil moisture. All of them were compared with observed Geodetic Angular Momentum (GAM), excitations of polar motion. The spectra of these excitation functions of polar motion and residual geodetic excitation function G-A-O obtained from GAM by elimination of atmospheric and oceanic excitation functions were computed too. Phasor diagrams of the seasonal components of the polar motion excitation functions of all HAM excitation functions as well as of two GRACE solutions: CSR, CNES were determined and discussed.

  10. Nonlinear frequency response of parametrically excited functionally graded Timoshenko beams with a crack

    NASA Astrophysics Data System (ADS)

    Yang, J.; Yan, T.

    2010-06-01

    This paper investigates the nonlinear dynamic frequency response of a Timoshenko beam made of functionally graded materials (FGMs) with an open edge crack. The beam is clamped and subjected to an axial parametric excitation consisting of a static compressive force and a harmonic excitation force. Theoretical formulations are based on Timoshenko shear deformable beam theory, von Karman type geometric nonlinearity and rotational spring model. Hamilton's principle is used to derive the nonlinear partial differential equations which are transformed into nonlinear ordinary differential equation by using the Least Squares method and Galerkin technique. The nonlinear natural frequencies and excitation frequency-amplitude response curves are obtained by employing Runge-Kutta method and multiple scale method, respectively. A parametric study is conducted to study the effects of material property distribution, crack depth, crack location, excitation frequency, and slenderness ratio on the nonlinear dynamic characteristics of parametrically excited, cracked FGM Timoshenko beams.

  11. How Strange is the Proton?

    SciTech Connect

    Piotr Decowski

    2006-11-15

    The paper discusses application of parity violating polarized electron scattering off nucleons to study strange form factors of the nucleon. The results from the recent HAPPEX experiment are discussed in more detail.

  12. Strangeness and onset of deconfinement

    SciTech Connect

    Becattini, F.

    2012-05-15

    I will review the current status of global strangeness production in relativistic heavy-ion collisions with particular emphasis on recent results from core-corona model. I will discuss its relevance for the detection of the onset of deconfinement.

  13. Torsional oscillations of strange stars

    NASA Astrophysics Data System (ADS)

    Mannarelli, Massimo

    2014-11-01

    Strange stars are one of the hypothetical compact stellar objects that can be formed after a supernova explosion. The existence of these objects relies on the absolute stability of strange collapsed quark matter with respect to standard nuclear matter. We discuss simple models of strange stars with a bare quark matter surface, thus standard nuclear matter is completely absent. In these models an electric dipole layer a few hundreds Fermi thick should exist close to the star surface. Studying the torsional oscillations of the electrically charged layer we estimate the emitted power, finding that it is of the order of 1045 erg/s, meaning that these objects would be among the brightest compact sources in the heavens. The associated relaxation times are very uncertain, with values ranging between microseconds and minutes, depending on the crust thickness. Although part of the radiated power should be absorbed by the electrosphere surrounding the strange star, a sizable fraction of photons should escape and be detectable.

  14. Relativistic Energy Density Functionals: Exotic modes of excitation

    SciTech Connect

    Vretenar, D.; Paar, N.; Marketin, T.

    2008-11-11

    The framework of relativistic energy density functionals has been applied to the description of a variety of nuclear structure phenomena, not only in spherical and deformed nuclei along the valley of {beta}-stability, but also in exotic systems with extreme isospin values and close to the particle drip-lines. Dynamical aspects of exotic nuclear structure have been investigated with the relativistic quasiparticle random-phase approximation. We present results for the evolution of low-lying dipole (pygmy) strength in neutron-rich nuclei, and charged-current neutrino-nucleus cross sections.

  15. Communication: Exciton analysis in time-dependent density functional theory: How functionals shape excited-state characters

    NASA Astrophysics Data System (ADS)

    Mewes, Stefanie A.; Plasser, Felix; Dreuw, Andreas

    2015-11-01

    Excited-state descriptors based on the one-particle transition density matrix referring to the exciton picture have been implemented for time-dependent density functional theory. State characters such as local, extended ππ∗, Rydberg, or charge transfer can be intuitively classified by simple comparison of these descriptors. Strong effects of the choice of the exchange-correlation kernel on the physical nature of excited states can be found and decomposed in detail leading to a new perspective on functional performance and the design of new functionals.

  16. Strange Star Surface: A Crust with Nuggets

    SciTech Connect

    Jaikumar, Prashanth; Reddy, Sanjay; Steiner, Andrew W.

    2006-02-03

    We reexamine the surface composition of strange stars. Strange quark stars are hypothetical compact stars which could exist if strange quark matter was absolutely stable. It is widely accepted that they are characterized by an enormous density gradient (10{sup 26} g/cm{sup 4}) and large electric fields at the surface. By investigating the possibility of realizing a heterogeneous crust, comprised of nuggets of strange quark matter embedded in an uniform electron background, we find that the strange star surface has a much reduced density gradient and negligible electric field. We comment on how our findings will impact various proposed observable signatures for strange stars.

  17. Asymmetries between strange and antistrange particle production inpion-proton interactions

    SciTech Connect

    Gutierrez, T.D.; Vogt, R.

    2002-01-29

    Recent measurements of the asymmetries between Feynman x-distributions of strange and antistrange hadrons in {pi}{sup -}A interactions show a strong effect as a function of x{sub F}. We calculate strange hadron production in the context of the intrinsic model and make predictions for particle/antiparticle asymmetries in these interactions.

  18. Gravimetric excitation function of polar motion from the GRACE RL05 solution

    NASA Astrophysics Data System (ADS)

    Nastula, Y.

    2014-12-01

    Impact of land hydrosphere on polar motion excitation is still not as well known as the impact of the angular momentum of the atmosphere and ocean. Satellite mission Gravity Recovery and Climate Experiment (GRACE) from 2002 provides additional information about mass distribution of the land hydrosphere. However, despite the use of similar computational procedures, the differences between GRACE data series made available by the various centers of computations are still considerable. In the paper we compare three series of gravimetric excitation functions of polar motion determined from Rl05 GRACE solution from the Center for Space Research (CSR), the Jet Propulsion Laboratory (JPL) and the GeoForschungsZentrum (GFZ). These data are used to determine the gravimetric polar motion excitation function. Gravimetric signal is compared also with the geodetic residuals computed by subtracting atmospheric and oceanic signals from geodetic excitation functions of polar motion. Gravimetric excitation functions obtained on the basis of JPL data differ significantly from the geodetic residuals while and the series obtained from CSR and GFZ are more compatible.

  19. Thick-target transmission method for excitation functions of interaction cross sections

    NASA Astrophysics Data System (ADS)

    Aikawa, M.; Ebata, S.; Imai, S.

    2016-09-01

    We propose a method, called as thick-target transmission (T3) method, to obtain an excitation function of interaction cross sections. In an ordinal experiment to measure the excitation function of interaction cross sections by the transmission method, we need to change the beam energy for each cross section. In the T3 method, the excitation function is derived from the beam attenuations measured at the targets of different thicknesses without changing the beam energy. The advantage of the T3 method is the simplicity and availability for radioactive beams. To confirm the availability, we perform a simulation for the 12C + 27Al system with the PHITS code instead of actual experiments. Our results have large uncertainties but well reproduce the tendency of the experimental data.

  20. Excited states properties of organic molecules: from density functional theory to the GW and Bethe-Salpeter Green's function formalisms.

    PubMed

    Faber, C; Boulanger, P; Attaccalite, C; Duchemin, I; Blase, X

    2014-03-13

    Many-body Green's function perturbation theories, such as the GW and Bethe-Salpeter formalisms, are starting to be routinely applied to study charged and neutral electronic excitations in molecular organic systems relevant to applications in photovoltaics, photochemistry or biology. In parallel, density functional theory and its time-dependent extensions significantly progressed along the line of range-separated hybrid functionals within the generalized Kohn-Sham formalism designed to provide correct excitation energies. We give an overview and compare these approaches with examples drawn from the study of gas phase organic systems such as fullerenes, porphyrins, bacteriochlorophylls or nucleobases molecules. The perspectives and challenges that many-body perturbation theory is facing, such as the role of self-consistency, the calculation of forces and potential energy surfaces in the excited states, or the development of embedding techniques specific to the GW and Bethe-Salpeter equation formalisms, are outlined. PMID:24516185

  1. Assessment of the ΔSCF density functional theory approach for electronic excitations in organic dyes

    SciTech Connect

    Kowalczyk, T.; Yost, S. R.; Van Voorhis, T.

    2010-01-01

    This paper assesses the accuracy of the ΔSCF method for computing low-lying HOMO→LUMO transitions in organic dye molecules. For a test set of vertical excitation energies of 16 chromophores, surprisingly similar accuracy is observed for time-dependent density functional theory and for ΔSCF density functional theory. In light of this performance, we reconsider the ad hoc ΔSCF prescription and demonstrate that it formally obtains the exact stationary density within the adiabatic approximation, partially justifying its use. The relative merits and future prospects of ΔSCF for simulating individual excited states are discussed.

  2. Disagreement between capture probabilities extracted from capture and quasi-elastic backscattering excitation functions

    NASA Astrophysics Data System (ADS)

    Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.; Gomes, R. P. S.

    2014-12-01

    Experimental quasi-elastic backscattering and capture (fusion) excitation functions are usually used to extract the s -wave capture probabilities for the heavy-ion reactions. We investigated the 16O + 120Sn , 144Sm , 208Pb systems at energies near and below the corresponding interaction barriers and concluded that the probabilities extracted from quasi-elastic data are much larger than the ones extracted from fusion excitation functions at sub and deep-sub barrier energies. This seems to be a reasonable explanation for the known disagreement observed in the literature for the nuclear potential diffuseness derived from both methods.

  3. A Study of Double-Charm and Charm-Strange Baryons inElectron-Positron Annihilations

    SciTech Connect

    Edwards, Adam J.; /SLAC

    2007-10-15

    In this dissertation I describe a study of double-charm and charm-strange baryons based on data collected with the BABAR Detector at the Stanford Linear Accelerator Center. In this study I search for new baryons and make precise measurements of their properties and decay modes. I seek to verify and expand upon double-charm and charm-strange baryon observations made by other experiments. The BABAR Detector is used to measure subatomic particles that are produced at the PEP-II storage rings. I analyze approximately 300 million e+e- {yields} c{bar c} events in a search for the production of double-charm baryons. I search for the double-charm baryons {Xi}{sup +}{sub cc} (containing the quarks ccd) and {Xi}{sup ++}{sub cc} (ccu) in decays to {Lambda}{sup +}{sub c}K{sup -}{pi}{sup +} and {Lambda}{sup +}{sub c}K{sup -}{pi}{sup +}{pi}{sup +}, respectively. No statistically significant signals for their production are found, and upper limits on their production are determined. Statistically significant signals for excited charm-strange baryons are observed with my analysis of approximately 500 million e+e- {yields} c{bar c} events. The charged charm-strange baryons {Xi}{sub c}(2970){sup +}, {Xi}{sub c}(3055){sup +}, {Xi}{sub c}(3123){sup +} are found in decays to {Lambda}{sup +}{sub c}K{sup -}{pi}{sup +}, the same decay mode used in the {Xi}{sup +}{sub cc} search. The neutral charm-strange baryon {Xi}{sub c}(3077){sup 0} is observed in decays to {Lambda}{sup +}{sub c}K{sub 8}{pi}{sup -}. I also search for excited charm-strange baryon decays to {Lambda}{sup +}{sub c}K{sub 8}, {Lambda}{sup +}{sub c}K{sup -}, {Lambda}{sup +}{sub c}K{sub 8}{pi}{sup -}{pi}{sup +}, and {Lambda}{sup +}{sub c}K{sup -}{pi}{sup -}{pi}{sup +}. No significant charm-strange baryon signals a f h these decay modes. For each excited charm-strange baryon state that I observe, I measure its mass, natural width (lifetime), and production rate. The properties of these excited charm-strange baryons and their

  4. Investigation of Multiconfigurational Short-Range Density Functional Theory for Electronic Excitations in Organic Molecules.

    PubMed

    Hubert, Mickaël; Hedegård, Erik D; Jensen, Hans Jørgen Aa

    2016-05-10

    Computational methods that can accurately and effectively predict all types of electronic excitations for any molecular system are missing in the toolbox of the computational chemist. Although various Kohn-Sham density-functional methods (KS-DFT) fulfill this aim in some cases, they become inadequate when the molecule has near-degeneracies and/or low-lying double-excited states. To address these issues we have recently proposed multiconfiguration short-range density-functional theory-MC-srDFT-as a new tool in the toolbox. While initial applications for systems with multireference character and double excitations have been promising, it is nevertheless important that the accuracy of MC-srDFT is at least comparable to the best KS-DFT methods also for organic molecules that are typically of single-reference character. In this paper we therefore systematically investigate the performance of MC-srDFT for a selected benchmark set of electronic excitations of organic molecules, covering the most common types of organic chromophores. This investigation confirms the expectation that the MC-srDFT method is accurate for a broad range of excitations and comparable to accurate wave function methods such as CASPT2, NEVPT2, and the coupled cluster based CC2 and CC3. PMID:27058733

  5. Strange Erosional Features

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 19 December 2003

    The strange erosional pattern seen in this THEMIS visible image differs greatly from the surrounding terrain of Lycus Sulchi (see context image). The crescent-shaped erosional pits trend in the southwest-northeast direction, indicating a dominant wind direction from the southwest. Why these pits eroded in the shapes that they did, however, is a mystery.

    Image information: VIS instrument. Latitude 18.6, Longitude 214.6 East (145.4 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  6. Analysis of Real Ship Rolling Dynamics under Wave Excitement Force Composed of Sums of Cosine Functions

    SciTech Connect

    Zhang, Y. S.; Cai, F.; Xu, W. M.

    2011-09-28

    The ship motion equation with a cosine wave excitement force describes the slip moments in regular waves. A new kind of wave excitement force model, with the form as sums of cosine functions was proposed to describe ship rolling in irregular waves. Ship rolling time series were obtained by solving the ship motion equation with the fourth-order-Runger-Kutta method. These rolling time series were synthetically analyzed with methods of phase-space track, power spectrum, primary component analysis, and the largest Lyapunove exponent. Simulation results show that ship rolling presents some chaotic characteristic when the wave excitement force was applied by sums of cosine functions. The result well explains the course of ship rolling's chaotic mechanism and is useful for ship hydrodynamic study.

  7. Excitation functions for actinides produced in the interactions of sup 31 P with sup 248 Cm

    SciTech Connect

    Leyba, J.D.; Henderson, R.A.; Hall, H.L.; Czerwinski, K.R.; Kadkhodayan, B.A.; Kreek, S.A.; Brady, E.K.; Gregorich, K.E.; Lee, D.M.; Nurmia, M.J.; Hoffman, D.C. Nuclear Science Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California )

    1991-11-01

    Excitation functions have been measured for the production of various isotopes of Bk, Cf, Es, and Fm from the interactions of 174- and 239-MeV {sup 31}P projectiles with {sup 248}Cm. The isotopic distributions were symmetric and displayed full widths at half maximum of 2.5, 2.5, and 2.25 mass units for Bk, Cf, and Fm, respectively. The maxima of the isotopic distributions occur for those reaction channels which involve the exchange of the fewest number of nucleons between the target and projectile for which the calculated excitation energy is a positive quantity. The maxima of the excitation functions occur at those projectile energies which are consistent with the calculated reaction barriers based upon a binary reaction mechanism. The effects of the odd proton in the {sup 31}P projectile on the final isotopic distributions are discussed.

  8. Production of strange particles in hadronization processes

    SciTech Connect

    Hofmann, W.

    1987-08-01

    Strange particles provide an important tool for the study of the color confinement mechanisms involved in hadronization processes. We review data on inclusive strange-particle production and on correlations between strange particles in high-energy reactions, and discuss phenomenological models for parton fragmentation. 58 refs., 24 figs.

  9. Nucleon strangeness form factors and moments of PDF

    SciTech Connect

    Doi, Takumi; Deka, Mridupawan; Dong, Shao-Jing; Draper, Terrence; Liu, Keh-Fei; Mankame, Devdatta; Mathur, Nilmani; Streuer, Thomas

    2011-10-24

    The calculation of the nucleon strangeness form factors from N{sub f} = 2+1 clover fermion lattice QCD is presented. Disconnected insertions are evaluated using the Z(4) stochastic method, along with unbiased subtractions from the hopping parameter expansion. We find that increasing the number of nucleon sources for each configuration improves the signal significantly. We obtain G{sub M}{sup s}(0) = -0.017(25)(07), which is consistent with experimental values, and has an order of magnitude smaller error. Preliminary results for the strangeness contribution to the second moment of the parton distribution function are also presented.

  10. Physics of psychophysics: Stevens and Weber-Fechner laws are transfer functions of excitable media

    NASA Astrophysics Data System (ADS)

    Copelli, Mauro; Roque, Antônio C.; Oliveira, Rodrigo F.; Kinouchi, Osame

    2002-06-01

    Sensory arrays made of coupled excitable elements can improve both their input sensitivity and dynamic range due to collective nonlinear wave properties. This mechanism is studied in a neural network of electrically coupled (e.g., via gap junctions) elements subject to a Poisson signal process. The network response interpolates between a Weber-Fechner logarithmic law, and a Stevens power law depending on the relative refractory period of the cell. Therefore, these nonlinear transformations of the input level could be performed in the sensory periphery simply due to a basic property: the transfer function of excitable media.

  11. Motor cortex excitability changes within 8 hours after ischaemic stroke may predict the functional outcome.

    PubMed

    Di Lazzaro, V; Oliviero, A; Profice, P; Saturno, E; Pilato, F; Tonali, P

    1999-06-01

    Motor evoked potentials after magnetic transcranial stimulation and the excitability of the motor cortex to increasing magnetic stimulus intensities were evaluated in six patients with hemiparesis after ischaemic stroke within 8 hours after stroke. The latencies of motor evoked potentials were normal in all patients. After stimulation of the ischaemic hemisphere we obtained responses comparable with the contralateral ones in two patients (mean NIH score 2 (SD 0)) and this group was completely asymptomatic after 15 days (NIH score 0). In four patients the excitability of the motor cortex involved by the ischaemia was reduced and magnetic motor threshold was higher than that of the spared motor cortex. This finding was associated with a poor motor recovery and the NIH score after 15 days was unchanged (NIH score 1.75 (SD 1.5)). The present data suggest that the evaluation of the excitability of motor cortex may offer a mean of predicting functional outcome following stroke. PMID:10461555

  12. Parameter-free exchange potential for excitation in the density-functional theory: Application to excitation energies within the fractional-occupation approach

    NASA Astrophysics Data System (ADS)

    Nagy, Á.

    1990-10-01

    The density-functional theory for ensembles of fractional occupation formulated by Gross, Oliveira, and Kohn [Phys. Rev. A 37, 2821 (1988)] has been applied. The excitation energies of several atoms have been determined using a parameter-free exchange potential of Gáspár [Acta Phys. Hung. 35, 213 (1974)]. The calculated excitation energies are in good agreement with the experimental values.

  13. A strange cat in Dublin

    NASA Astrophysics Data System (ADS)

    O'Raifeartaigh, Cormac

    2012-11-01

    Not many life stories in physics involve Nazis, illicit sex, a strange cat and the genetic code. Thus, a new biography of the great Austrian physicist Erwin Schrödinger is always of interest, and with Erwin Schrödinger and the Quantum Revolution, veteran science writer John Gribbin does not disappoint.

  14. Strange-quark-matter stars

    SciTech Connect

    Glendenning, N.K.

    1989-11-01

    We investigate the implications of rapid rotation corresponding to the frequency of the new pulsar reported in the supernovae remnant SN1987A. It places very stringent conditions on the equation of state if the star is assumed to be bound by gravity alone. We find that the central energy density of the star must be greater than 13 times that of nuclear density to be stable against the most optimistic estimate of general relativistic instabilities. This is too high for the matter to consist of individual hadrons. We conclude that it is implausible that the newly discovered pulsar, if its half-millisecond signals are attributable to rotation, is a neutron star. We show that it can be a strange quark star, and that the entire family of strange stars can sustain high rotation if strange matter is stable at an energy density exceeding about 5.4 times that of nuclear matter. We discuss the conversion of a neutron star to strange star, the possible existence of a crust of heavy ions held in suspension by centrifugal and electric forces, the cooling and other features. 34 refs., 10 figs., 1 tab.

  15. How strange is pion electroproduction?

    NASA Astrophysics Data System (ADS)

    Gorchtein, Mikhail; Spiesberger, Hubert; Zhang, Xilin

    2016-01-01

    We consider pion production in parity-violating electron scattering (PVES) in the presence of nucleon strangeness in the framework of partial wave analysis with unitarity. Using the experimental bounds on the strange form factors obtained in elastic PVES, we study the sensitivity of the parity-violating asymmetry to strange nucleon form factors. For forward kinematics and electron energies above 1 GeV, we observe that this sensitivity may reach about 20% in the threshold region. With parity-violating asymmetries being as large as tens p.p.m., this study suggests that threshold pion production in PVES can be used as a promising way to better constrain strangeness contributions. Using this model for the neutral current pion production, we update the estimate for the dispersive γZ-box correction to the weak charge of the proton. In the kinematics of the Qweak experiment, our new prediction reads Re □γZV (E = 1.165 GeV) = (5.58 ± 1.41) ×10-3, an improvement over the previous uncertainty estimate of ± 2.0 ×10-3. Our new prediction in the kinematics of the upcoming MESA/P2 experiment reads Re □γZV (E = 0.155 GeV) = (1.1 ± 0.2) ×10-3.

  16. Measurement of fusion excitation functions in the system {sup 78}Kr + {sup 100}Mo

    SciTech Connect

    Rehm, K.E.; Jiang, C.L.; Esbensen, H.

    1995-08-01

    Earlier measurements of fusion reactions involving {sup 78}Kr and {sup 100}Mo projectiles and Ni-targets showed surprisingly large fusion yields at low energies which could not be explained by coupled-channels calculations. The main difference to similar measurements involving the neighboring {sup 86}Kr and {sup 92}Mo isotopes was the different slope of the excitation functions at sub-barrier energies. An analysis of a variety of experiments showed a correlation between the nuclear structure and the slope of the excitation functions, with the {open_quotes}soft{close_quotes} transitional nuclei ({sup 78}Kr, {sup 100}Mo) exhibiting shallower slopes than the {open_quotes}stiff{close_quotes} nuclei ({sup 86}Kr, {sup 92}Mo) measured at the same energies with respect to the barrier. In this experiment we studied the fusion excitation function involving two transitional nuclei {sup 78}Kr + {sup 100}Mo. The measurements were performed with {sup 78}Kr beams from the ECR source at energies between 285-370 MeV. Separation of the evaporation nucleus from the elastically scattered particles was achieved by measuring time-of-flight and magnetic rigidity in the gas-filled spectrograph. The data were completely analyzed. A comparison of the cross sections with measurements for the system {sup 86}Kr + {sup 92}Mo populating the same compound nucleus {sup 178}Pt. It shows good agreement at the highest energies, but quite different falloffs of the excitation functions toward lower energies. Coupled-channels calculations, including multi-phonon excitation for the two systems, are being performed.

  17. The functional nanostructures based on the bipolymers fragments with unidirect excitations energy transfer for nanophotonics

    NASA Astrophysics Data System (ADS)

    Yashchuk, V. M.; Kudrya, V. Yu.; Dubey, I. Ya.; Fedorovich, R. D.; Suga, H.; Savchenko, I. O.; Golovach, G. P.

    2007-06-01

    The results of the design, synthesis and investigations of the compounds (possessing predicted unidirect excitations conductivity) containing several π-electron systems (including nucleotides - the short DNA-fragments) are reported. The predicted processes of unidirect triplet excitations transfer in all investigated compounds were proved. The nature of electronic excitations traps in the compounds investigated is discussed. For the molecular systems composed from the DNA-fragments spectral investigations show the adenosine-thymidine-sequences are such traps in these compounds as well as the DNA [1]. The energy levels lowering existence from chromophore to chromophore along the molecular system gives the ground to predict not only unidirect neutral excitation transfer but unidirect charge carrier current. Really the "diode" I(U) characteristic for metal-organic system of gold islands connected by π-electron-containing molecules was observed. This gives the possibility to propose these compounds to be used for nanoelectronic devices design. Computer simulations of electronic excitations passing through the oligomer functional macromolecule taking into account reverse exciton currents show such type macromolecules are perspective for applying in nanophotonics.

  18. Functional neuroimaging of inner fields-of-view with 2D-selective RF excitations.

    PubMed

    Finsterbusch, Jürgen

    2013-09-01

    Echo-planar imaging is widely used in functional neuroimaging but suffers from its pronounced sensitivity to field inhomogeneities that cause geometric distortions and image blurring which both limit the effective in-plane resolution achievable. In this work, it is shown how inner-field-of-view techniques based on 2D-selective RF excitations (2DRF) can be applied to reduce the field-of-view in the phase-encoding direction without aliasing and increase the in-plane resolution accordingly. Free-induction-decay (FID) EPI and echo-train-shifted (T2*-weighted) and standard (T2-weighted) spin-echo (SE) EPI with in-plane resolutions of up to 0.5×1.0mm(2) (slice thickness 5mm) were acquired at 3T. Unwanted signal contributions of 2DRF side excitations were shifted out of the object (FID-EPI) or of the refocusing plane by tilting the excitation plane (SE-EPI). Brain activation in healthy volunteers was investigated with checkerboard and finger-tapping block-design paradigms. Brain activation could be detected with all sequences and contrasts, most reliably with FID-EPI due to its higher signal amplitude and the longer 2DRF excitation that are more sensitive to magnetic field inhomogeneities. In conclusion, inner-FOV EPI based on 2DRF excitations could help to improve the spatial resolution of fMRI of focal target regions, e.g., for applications in the spinal cord. PMID:23602726

  19. Vertical Singlet Excitations on Adenine Dimer: A Time Dependent Density Functional Study

    NASA Astrophysics Data System (ADS)

    Crespo-Hernández, Carlos E.; Marai, Christopher N. J.

    2007-12-01

    The condense phase, excited state dynamics of the adenylyl(3'→5')adenine (ApA) dinucleotide has been previously studied using transient absorption spectroscopy with femtosecond time resolution (Crespo-Hernández et al. Chem. Rev. 104, 1977-2019 (2004)). An ultrafast and a long-lived component were observed with time constants of <1 ps and 60±16 ps, respectively. Comparison of the time constants measured for the dinucleotide with that for the adenine nucleotide suggested that the fast component observed in ApA could be assigned to monomer dynamics. The long-lived component observed in ApA was assigned to an excimer state that originates from a fraction of base stacked conformations present at the time of excitation. In this contribution, supermolecule calculations using the time dependent implementation of density functional theory is used to provide more insights on the origin of the initial Franck-Condon excitations. Monomer-like, localized excitations are observed for conformations having negligible base stacking interactions, whereas delocalized excitations are predicted for conformations with significant vertical base-base overlap.

  20. Impact of Reaction Cross Section on the Unified Description of Fusion Excitation Function

    NASA Astrophysics Data System (ADS)

    Basrak, Z.; Eudes, P.; de la Mota, V.; Sébille, F.; Royer, G.

    A systematics of over 300 complete and incomplete fusion cross section data points covering energies beyond the barrier for fusion is presented. Owing to a usual reduction of the fusion cross sections by the total reaction cross sections and an original scaling of energy, a fusion excitation function common to all the data points is established. A universal description of the fusion exci- tation function relying on basic nuclear concepts is proposed and its dependence on the reaction cross section used for the cross section normalization is discussed. The pioneering empirical model proposed by Bass in 1974 to describe the complete fusion cross sections is rather successful for the incomplete fusion too and provides cross section predictions in satisfactory agreement with the observed universality of the fusion excitation function. The sophisticated microscopic transport DYWAN model not only reproduces the data but also predicts that fusion reaction mechanism disappears due to weakened nuclear stopping power around the Fermi energy.

  1. Chaotic /strange/ and periodic behavior in instability saturation by the oscillating two-stream instability

    NASA Technical Reports Server (NTRS)

    Russell, D. A.; Ott, E.

    1981-01-01

    The nonlinear Schroedinger equation with linear growth and damping is truncated to three waves. The resulting system of nonlinear ordinary differential equations describes the excitation of linearly damped waves by the oscillating two-stream instability driven by a linearly unstable pump wave. This system represents a simple model for the nonlinear saturation of a linearly unstable wave. The model is examined analytically and numerically as a function of the dimensionless parameters of the system. It is found that the model can exhibit a wealth of characteristic dynamical behavior including stationary equilibria, Hopf bifurcations to periodic orbits, period doubling bifurcations, chaotic solutions characteristic of a strange attractor, tangent bifurcations from chaotic to periodic solutions, transient chaos, and hysteresis. Many of these features are shown to be explainable on the basis of one-dimensional maps. In the case of chaotic solutions, evidence for the presence of a strange attractor is provided by demonstrating Cantor set-like structure (i.e., scale invariance) in the surface of section.

  2. Strangeness and charm in nuclear matter

    NASA Astrophysics Data System (ADS)

    Tolos, Laura; Cabrera, Daniel; Garcia-Recio, Carmen; Molina, Raquel; Nieves, Juan; Oset, Eulogio; Ramos, Angels; Romanets, Olena; Salcedo, Lorenzo Luis

    2013-09-01

    The properties of strange (K, Kbar and K) and open-charm (D, Dbar and D*) mesons in dense matter are studied using a unitary approach in coupled channels for meson-baryon scattering. In the strangeness sector, the interaction with nucleons always comes through vector-meson exchange, which is evaluated by chiral and hidden gauge Lagrangians. For the interaction of charmed mesons with nucleons we extend the SU(3) Weinberg-Tomozawa Lagrangian to incorporate spin-flavor symmetry and implement a suitable flavor symmetry breaking. The in-medium solution for the scattering amplitude accounts for Pauli blocking effects and meson self-energies. On one hand, we obtain the K, Kbar and K spectral functions in the nuclear medium and study their behaviour at finite density, temperature and momentum. We also make an estimate of the transparency ratio of the γA→K+KA‧ reaction, which we propose as a tool to detect in-medium modifications of the K meson. On the other hand, in the charm sector, several resonances with negative parity are generated dynamically by the s-wave interaction between pseudoscalar and vector meson multiplets with 1/2+ and 3/2+ baryons. The properties of these states in matter are analyzed and their influence on the open-charm meson spectral functions is studied. We finally discuss the possible formation of D-mesic nuclei at FAIR energies.

  3. A relativistic time-dependent density functional study of the excited states of the mercury dimer.

    PubMed

    Kullie, Ossama

    2014-01-14

    In previous works on Zn2 and Cd2 dimers we found that the long-range corrected CAMB3LYP gives better results than other density functional approximations for the excited states, especially in the asymptotic region. In this paper, we use it to present a time-dependent density functional (TDDFT) study for the ground-state as well as the excited states corresponding to the (6s(2) + 6s6p), (6s(2) + 6s7s), and (6s(2) + 6s7p) atomic asymptotes for the mercury dimer Hg2. We analyze its spectrum obtained from all-electron calculations performed with the relativistic Dirac-Coulomb and relativistic spinfree Hamiltonian as implemented in DIRAC-PACKAGE. A comparison with the literature is given as far as available. Our result is excellent for the most of the lower excited states and very encouraging for the higher excited states, it shows generally good agreements with experimental results and outperforms other theoretical results. This enables us to give a detailed analysis of the spectrum of the Hg2 including a comparative analysis with the lighter dimers of the group 12, Cd2, and Zn2, especially for the relativistic effects, the spin-orbit interaction, and the performance of CAMB3LYP and is enlightened for similar systems. The result shows, as expected, that spinfree Hamiltonian is less efficient than Dirac-Coulomb Hamiltonian for systems containing heavy elements such as Hg2. PMID:24437874

  4. A relativistic time-dependent density functional study of the excited states of the mercury dimer

    NASA Astrophysics Data System (ADS)

    Kullie, Ossama

    2014-01-01

    In previous works on Zn2 and Cd2 dimers we found that the long-range corrected CAMB3LYP gives better results than other density functional approximations for the excited states, especially in the asymptotic region. In this paper, we use it to present a time-dependent density functional (TDDFT) study for the ground-state as well as the excited states corresponding to the (6s2 + 6s6p), (6s2 + 6s7s), and (6s2 + 6s7p) atomic asymptotes for the mercury dimer Hg2. We analyze its spectrum obtained from all-electron calculations performed with the relativistic Dirac-Coulomb and relativistic spinfree Hamiltonian as implemented in DIRAC-PACKAGE. A comparison with the literature is given as far as available. Our result is excellent for the most of the lower excited states and very encouraging for the higher excited states, it shows generally good agreements with experimental results and outperforms other theoretical results. This enables us to give a detailed analysis of the spectrum of the Hg2 including a comparative analysis with the lighter dimers of the group 12, Cd2, and Zn2, especially for the relativistic effects, the spin-orbit interaction, and the performance of CAMB3LYP and is enlightened for similar systems. The result shows, as expected, that spinfree Hamiltonian is less efficient than Dirac-Coulomb Hamiltonian for systems containing heavy elements such as Hg2.

  5. Time-dependent density functional theory predictions of the vertical excitation energies of silanones as models for the excitation process in porous silicon.

    PubMed

    Dixon, David A; Gole, James L

    2005-08-11

    Time-dependent density functional theory calculations with a proper treatment of the asymptotic form of the exchange-correlation potential have been performed on R(R')Si=O to predict vertical excitation energies. The species R(R')Si=O is used as a model for the binding of the -(R)Si=O chromophore to a porous silicon surface. The calculated vertical excitation energies are substantially lower than those determined previously and show that vertical excitation of the lone chromophore is possible for all types of substituents including electronegative ones with KrF laser excitation in contrast to other predictions. If the substituents are electropositive, the chromophore can also be excited by a nitrogen laser. These results, in concert with the effect of the porous silicon surface on the R(R')Si=O excited states, confirm our previous explanation of the photoluminescence of porous silicon as being due to the presence of Si=O chromophores and provide new insights into the photoexcitation process. The results show that the differences in the vertical and adiabatic excitation energies are strongly dependent on whether the substituents are electronegative or electropositive with the former leading to larger differences and the latter leading to smaller differences. The results for the energy differences are explained in terms of the changes in the Si=O bond length on vertical excitation and on the changes in bond angles, which are related to the ability of the Si center in the excited state to undergo an inversion process. PMID:16852877

  6. Measurement of the 208Pb(52Cr, n)259Sg Excitation Function

    SciTech Connect

    Folden III, C.M.; Dragojevic, I.; Dullmann, Ch.E.; Eichler, R.; Garcia, M.A.; Gates, J.M.; Nelson, S.L.; Sudowe, R.; Gregorich, K.E.; Hoffman, D.C.; Nitsche, H.

    2010-03-19

    The excitation function for the 208Pb(52Cr, n)259Sg reaction has been measured using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. The maximum cross section of pb is observed at a center-of-target laboratory-frame energy of 253.0 MeV. In total, 25 decay chains originating from 259Sg were observed and the measured decay properties are in good agreement with previous reports. In addition, a partial excitation function for the 208Pb(52Cr, 2n)258Sg reaction was obtained, and an improved 258Sg half-life of ms was calculated by combining all available experimental data.

  7. Generating functions and stability study of multivariate self-excited epidemic processes

    NASA Astrophysics Data System (ADS)

    Saichev, A. I.; Sornette, D.

    2011-09-01

    We present a stability study of the class of multivariate self-excited Hawkes point processes, that can model natural and social systems, including earthquakes, epileptic seizures and the dynamics of neuron assemblies, bursts of exchanges in social communities, interactions between Internet bloggers, bank network fragility and cascading of failures, national sovereign default contagion, and so on. We present the general theory of multivariate generating functions to derive the number of events over all generations of various types that are triggered by a mother event of a given type. We obtain the stability domains of various systems, as a function of the topological structure of the mutual excitations across different event types. We find that mutual triggering tends to provide a significant extension of the stability (or subcritical) domain compared with the case where event types are decoupled, that is, when an event of a given type can only trigger events of the same type.

  8. Measurement of excitation functions in alpha induced reactions on natCu

    NASA Astrophysics Data System (ADS)

    Shahid, Muhammad; Kim, Kwangsoo; Kim, Guinyun; Zaman, Muhammad; Nadeem, Muhammad

    2015-09-01

    The excitation functions of 66,67,68Ga, 62,63,65Zn, 61,64Cu, and 58,60Co radionuclides in the natCu(α, x) reaction were measured in the energy range from 15 to 42 MeV by using a stacked-foil activation method at the MC-50 cyclotron of the Korean Institute of Radiological and Medical Sciences. The measured results were compared with the literature data as well as the theoretical values obtained from the TENDL-2013 and TENDL-2014 libraries based on the TALYS-1.6 code. The integral yields for thick targets of the produced radionuclides were also determined from the measured excitation functions and the stopping power of natural copper.

  9. Derivation of capture cross sections from quasi-elastic excitation functions

    NASA Astrophysics Data System (ADS)

    Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.; Gomes, P. R. S.

    2013-04-01

    The relationship between the quasi-elastic excitation function and the capture cross section is derived. The quasi-elastic data is shown to be a useful tool to extract the capture cross sections and the angular momenta of the captured systems for the reactions 16O+144,154Sm,208Pb, 20Ne+208Pb, and 32S+90,96Zr near and above the Coulomb barrier energies.

  10. New results on mesons containing strange quarks

    SciTech Connect

    Aston, D.; Awaji, N.; Bienz, T.; Bird, F.; D'Amore, J.; Dunwoodie, W.; Endorf, R.; Fujii, K.; Hayashii, H.; Iwata, S.

    1987-01-01

    Recent results of strange and strangeonium mesons are presented. The data come from a high sensitivity study (4.1 ev/nb) of K/sup -/p interactions at 11 GeV/c using the LASS spectrometer at SLAC. The complete leading orbitally-excited K* series up through J/sup P/ = 5/sup -/ and a substantial number of the expected underlying states are observed decaying into K/sup -/..pi../sup +/, anti K/sub 3//sup 0/..pi../sup +/..pi../sup -/, and K eta final states, and new measurements are made of their masses, widths, and branching ratios. Production of strangeonium states via hypercharge exchange is observed into K/sub 3//sup 0/K/sub 3//sup 0/, K/sup -/K/sup +/, and K/sub 3//sup 0/K/sup + -/..pi../sup - +/ final states. The leading orbitally-excited phi series through J/sup P/ = 3/sup -/ is clearly seen and evidence is presented for additional high spin structure in the 2.2 GeV/c/sup 2/ region. No f/sub 2/(1720) is observed. The K/sub 3//sup 0/K/sup + -/..pi../sup - +/ spectrum is dominated by 1/sup +/(K* anti K + anti K* K) production in the region below 1.6 GeV/c/sup 2/. These results are compared with data on the same systems produced by different production mechanisms. 12 refs., 28 figs.

  11. Excitation Functions of α-INDUCED Reactions in Cobalt and Pre-Equilibrium Effects

    NASA Astrophysics Data System (ADS)

    Ansari, M. Afzal; Abd. Alslam, Mouner A.; Sathik, N. P. M.; Ismail, M.; Rashid, M. H.

    Excitation functions for the reactions (α,2n), (α,αn), (α,α2n), (α,α3n) and (α,2pn) have been measured using 57Co as a target up to 50 MeV α-particle energy. The stacked foil activation technique and γ-ray spectroscopy method has been employed. Measured excitation functions are compared with the geometry dependent hybrid (GDH) model. A comparison shows that the pure equilibrium (EQ) compound reaction mechanism is incapable of reproducing the experimental data while the pre-equilibrium (PE) reaction mechanism along with equilibrium (EQ) decay, where it is considered that pre-equilibrium emission of particles take place prior to the establishment of the thermodynamical equilibrium of the system, is able to reproduce the experimental data. The GDH model code ALICE-91 has been used for theoretical calculations. A value of initial exciton number n0=4 with configuration (2 neutron + 2 proton + 0 hole) has been found to give the satisfactory reproduction of experimental excitation functions.

  12. Influence of the excited states on the electron-energy distribution function in low-pressure microwave argon plasmas

    SciTech Connect

    Yanguas-Gil, A.; Cotrino, J.; Gonzalez-Elipe, A.R.

    2005-07-01

    In this work the influence of the excited states on the electron-energy distribution function has been determined for an argon microwave discharge at low pressure. A collisional-radiative model of argon has been developed taking into account the most recent experimental and theoretical values of argon-electron-impact excitation cross sections. The model has been solved along with the electron Boltzmann equation in order to study the influence of the inelastic collisions from the argon excited states on the electron-energy distribution function. Results show that under certain conditions the excited states can play an important role in determining the shape of the distribution function and the mean kinetic energy of the electrons, deplecting the high-energy tail due to inelastic processes from the excited states, especially from the 4s excited configuration. It has been found that from the populations of the excited states an excitation temperature can be defined. This excitation temperature, which can be experimentally determined by optical emission spectroscopy, is lower than the electron kinetic temperature obtained from the electron-energy distribution function.

  13. Open strangeness production in CLAS

    SciTech Connect

    G. Niculescu

    2003-05-01

    An extensive program dedicated to the study of open strangeness systems was established in Hall B at Jefferson Lab. This program takes full advantage of the excellent characteristics of the CEBAF accelerator combined with the almost complete angular coverage of the CLAS detector. A general overview of the program is given, as well as results for the angular dependence of the electroproduction of kaon-hyperon final states.

  14. Neutron stars and strange matter

    SciTech Connect

    Cooperstein, J.

    1986-01-01

    The likelihood is investigated that quark matter with strangeness of order unity resides in neutron stars. In the strong coupling regime near rho/sub 0/ this is found to be unlikely. Considering higher densities where perturbative expansions are used, we find a lower bound to be at 7rho/sub 0/ for the transition density. This is higher than the inferred density of observed neutron stars, and thus the transition to quark matter is precluded. 15 refs., 3 figs.

  15. Condensate wave function and elementary excitations of bosonic polar molecules: Beyond the first Born approximation

    NASA Astrophysics Data System (ADS)

    Huang, Chao-Chun; Wang, Daw-Wei; Wu, Wen-Chin

    2010-04-01

    We investigate the condensate wave function and elementary excitations of strongly interacting bosonic polar molecules in a harmonic trap, treating the scattering amplitude beyond the standard first Born approximation (FBA). By using an appropriate trial wave function in the variational method, effects of the leading-order correction beyond the FBA have been investigated and shown to be significantly enhanced when the system is close to the phase boundary of collapse. How such a leading-order effect of going beyond the FBA can be observed in a realistic experiment is also discussed.

  16. A closer look at the apparent correlation of structural and functional connectivity in excitable neural networks

    NASA Astrophysics Data System (ADS)

    Messé, Arnaud; Hütt, Marc-Thorsten; König, Peter; Hilgetag, Claus C.

    2015-01-01

    The relationship between the structural connectivity (SC) and functional connectivity (FC) of neural systems is a central focus in brain network science. It is an open question, however, how strongly the SC-FC relationship depends on specific topological features of brain networks or the models used for describing excitable dynamics. Using a basic model of discrete excitable units that follow a susceptible - excited - refractory dynamic cycle (SER model), we here analyze how functional connectivity is shaped by the topological features of a neural network, in particular its modularity. We compared the results obtained by the SER model with corresponding simulations by another well established dynamic mechanism, the Fitzhugh-Nagumo model, in order to explore general features of the SC-FC relationship. We showed that apparent discrepancies between the results produced by the two models can be resolved by adjusting the time window of integration of co-activations from which the FC is derived, providing a clearer distinction between co-activations and sequential activations. Thus, network modularity appears as an important factor shaping the FC-SC relationship across different dynamic models.

  17. Measurement of the fusion excitation function for 19O + 12C at near barrier energies

    NASA Astrophysics Data System (ADS)

    Singh, Varinderjit; Steinbach, T. K.; Vadas, J.; Wiggins, B. B.; Hudan, S.; Desouza, R. T.; Baby, L. T.; Tripathi, V.; Kuvin, S. A.; Wiedenhover, I.

    2015-10-01

    Fusion of neutron-rich light nuclei in the outer crust of an accreting neutron star has been proposed as responsible for triggering X-ray super-bursts. The underlying hypothesis in this proposition is that the fusion of neutron-rich nuclei is enhanced as compared to stable nuclei. To investigate this hypothesis, an experiment has been performed to measure the fusion excitation function for 18O and 19O nuclei incident on a 12C target. A beam of 19O was produced by the 18O(d,p) reaction at Florida State University and separated using the RESOLUT mass spectrometer. The resulting 19O beam bombarded a 100 μg/cm2 12C target at an intensity of 2-4 × 103 p/s. Evaporation residues resulting from the de-excitation of the fusion product were distinguished by measuring their energy and time-of-flight. Using silicon detectors, micro-channel plate detectors, and an ionization chamber, evaporation residues were detected in the angular range θlab <= 23° with high efficiency. Initial experimental results including measurement of the fusion cross-section to approximately the 100 mb level will be presented. The measured excitation function will be compared to theoretical predictions. Supported by the US DOE under Grand No. DEFG02-88ER-40404.

  18. Prospects for strangeness measurement in ALICE

    SciTech Connect

    Vernet, R.

    2008-09-15

    The study of strangeness production at LHC will bring significant information on the bulk chemical properties, its dynamics, and the hadronization mechanisms involved at these energies. The ALICE experiment will measure strange particles from topology (secondary vertices) and from resonance decays over a wide range in transverse momentum and shed light on this new QCD regime. These motivations will be presented as well as the identification performance of ALICE for strange hadrons.

  19. Double-hybrid density functional theory for excited electronic states of molecules

    NASA Astrophysics Data System (ADS)

    Grimme, Stefan; Neese, Frank

    2007-10-01

    Double-hybrid density functionals are based on a mixing of standard generalized gradient approximations (GGAs) for exchange and correlation with Hartree-Fock (HF) exchange and a perturbative second-order correlation part (PT2) that is obtained from the Kohn-Sham (GGA) orbitals and eigenvalues. This virtual orbital-dependent functional (dubbed B2PLYP) contains only two empirical parameters that describe the mixture of HF and GGA exchange (ax) and of the PT2 and GGA correlation (ac), respectively. Extensive testing has recently demonstrated the outstanding accuracy of this approach for various ground state problems in general chemistry applications. The method is extended here without any further empirical adjustments to electronically excited states in the framework of time-dependent density functional theory (TD-DFT) or the closely related Tamm-Dancoff approximation (TDA-DFT). In complete analogy to the ground state treatment, a scaled second-order perturbation correction to configuration interaction with singles (CIS(D)) wave functions developed some years ago by Head-Gordon et al. [Chem. Phys. Lett. 219, 21 (1994)] is computed on the basis of density functional data and added to the TD(A)-DFT/GGA excitation energy. The method is implemented by applying the resolution of the identity approximation and the efficiency of the code is discussed. Extensive tests for a wide variety of molecules and excited states (of singlet, triplet, and doublet multiplicities) including electronic spectra are presented. In general, rather accurate excitation energies (deviations from reference data typically <0.2eV) are obtained that are mostly better than those from standard functionals. Still, systematic errors are obtained for Rydberg (too low on average by about 0.3eV) and charge-transfer transitions but due to the relatively large ax parameter (0.53), B2PLYP outperforms most other functionals in this respect. Compared to conventional HF-based CIS(D), the method is more robust in

  20. Measurement of fusion excitation function for 7Li+64Ni near the barrier

    NASA Astrophysics Data System (ADS)

    Moin Shaikh, Md.; Roy, Subinit; Rajbanshi, S.; Mukherjee, A.; Pradhan, M. K.; Basu, P.; Pal, S.; Nanal, V.; Shrivastava, A.; Saha, S.; Pillay, R. G.

    2016-05-01

    Total fusion (TF) excitation function has been measured for the system 7Li + 64Ni at the energies near the Coulomb barrier of the system. The evaporation residue (ER) cross sections have been estimated through the online detection of characteristic γ-rays of the ERs. The summed ER cross sections yielding the experimental TF cross section have been compared with the theoretical one dimensional barrier penetration model (1DBPM) prediction. The measured and the model cross sections are very close to each other at above barrier energies. However, an enhancement of the experimental TF cross section with respect to the 1DBPM prediction is observed at below barrier energies. Coupled channels (CC) calculation with inelastic excitations alone could not explain the enhancement. The origin of the enhancement is identified as due to the enhanced population of the αxn channels.

  1. Is the sub-millisecond pulsar strange?

    NASA Technical Reports Server (NTRS)

    Frieman, Joshua A.; Olinto, Angela V.

    1989-01-01

    The possibility that the submillisecond pulsar from supernova 1987A is composed of strange matter is theoretically discussed. It is shown that for a range of hadron parameters, the maximum rotation rate of secularly stable strange stars may exceed that of the half-millisecond pulsar and the nonrotating maximum mass is greater than 1.52 solar mass. The low-mass companion(s) to SN1987A, inferred from the periodic modulations of the optical signal, can be accounted for by stable strange-matter lump(s) ejected from the young strange star.

  2. A relativistic time-dependent density functional study of the excited states of the mercury dimer

    SciTech Connect

    Kullie, Ossama E-mail: ossama.kullie@unistra.fr

    2014-01-14

    In previous works on Zn{sub 2} and Cd{sub 2} dimers we found that the long-range corrected CAMB3LYP gives better results than other density functional approximations for the excited states, especially in the asymptotic region. In this paper, we use it to present a time-dependent density functional (TDDFT) study for the ground-state as well as the excited states corresponding to the (6s{sup 2} + 6s6p), (6s{sup 2} + 6s7s), and (6s{sup 2} + 6s7p) atomic asymptotes for the mercury dimer Hg{sub 2}. We analyze its spectrum obtained from all-electron calculations performed with the relativistic Dirac-Coulomb and relativistic spinfree Hamiltonian as implemented in DIRAC-PACKAGE. A comparison with the literature is given as far as available. Our result is excellent for the most of the lower excited states and very encouraging for the higher excited states, it shows generally good agreements with experimental results and outperforms other theoretical results. This enables us to give a detailed analysis of the spectrum of the Hg{sub 2} including a comparative analysis with the lighter dimers of the group 12, Cd{sub 2}, and Zn{sub 2}, especially for the relativistic effects, the spin-orbit interaction, and the performance of CAMB3LYP and is enlightened for similar systems. The result shows, as expected, that spinfree Hamiltonian is less efficient than Dirac-Coulomb Hamiltonian for systems containing heavy elements such as Hg{sub 2}.

  3. Surface effects in color superconducting strange-quark matter

    SciTech Connect

    Oertel, Micaela; Urban, Michael

    2008-04-01

    Surface effects in strange-quark matter play an important role for certain observables which have been proposed in order to identify strange stars, and color superconductivity can strongly modify these effects. We study the surface of color superconducting strange-quark matter by solving the Hartree-Fock-Bogoliubov equations for finite systems ('strangelets') within the MIT bag model, supplemented with a pairing interaction. Because of the bag-model boundary condition, the strange-quark density is suppressed at the surface. This leads to a positive surface charge, concentrated in a layer of {approx}1 fm below the surface, even in the color-flavor locked (CFL) phase. However, since in the CFL phase all quarks are paired, this positive charge is compensated by a negative charge, which turns out to be situated in a layer of a few tens of fm below the surface, and the total charge of CFL strangelets is zero. We also study the surface and curvature contributions to the total energy. Because of the strong pairing, the energy as a function of the mass number is very well reproduced by a liquid-drop type formula with curvature term.

  4. Recasting wave functions into valence bond structures: A simple projection method to describe excited states.

    PubMed

    Racine, Julien; Hagebaum-Reignier, Denis; Carissan, Yannick; Humbel, Stéphane

    2016-03-30

    A method is proposed to obtain coefficients and weights of valence bond (VB) determinants from multi configurational wave functions. This reading of the wave functions can apply to ground states as well as excited states. The method is based on projection operators. Both energetic and overlap-based criteria are used to assess the quality of the resulting VB wave function. The approach gives a simple access to a VB rewriting for low-lying states, and it is applied to the allyl cation, to the allyl radical and to the ethene (notably to the V-state). For these states, large overlap between VB and multi reference wave functions are easily obtained. The approach proves to be useful to propose an interpretation of the nature of the V-state of ethene. PMID:26786547

  5. Excited-state nuclear forces on adiabatic potential-energy surfaces by time-dependent density-functional theory

    NASA Astrophysics Data System (ADS)

    Haruyama, Jun; Suzuki, Takahiro; Hu, Chunping; Watanabe, Kazuyuki

    2012-01-01

    We present a simple and computationally efficient method to calculate excited-state nuclear forces on adiabatic potential-energy surfaces (APES) from linear-response time-dependent density-functional theory within a real-space framework. The Casida ansatz, which has been validated for computing first-order nonadiabatic couplings in previous studies, was applied to the calculation of the excited-state forces. Our method is validated by the consistency of results in the lower excited states, which reproduce well those obtained by the numerical derivative of each APES. We emphasize the usefulness of this technique by demonstrating the excited-state molecular-dynamics simulation.

  6. Evolution of peripheral nerve function in humans: novel insights from motor nerve excitability

    PubMed Central

    Farrar, Michelle A; Park, Susanna B; Lin, Cindy S-Y; Kiernan, Matthew C

    2013-01-01

    While substantial alterations in myelination and axonal growth have been described during maturation, their interactions with the configuration and activity of axonal membrane ion channels to achieve impulse conduction have not been fully elucidated. The present study utilized axonal excitability techniques to compare the changes in nerve function across healthy infants, children, adolescents and adults. Multiple excitability indices (stimulus–response curve, strength–duration time constant, threshold electrotonus, current–threshold relationship and recovery cycle) combined with conventional neurophysiological measures were investigated in 57 subjects (22 males, 35 females; age range 0.46–24 years), stimulating the median motor nerve at the wrist. Maturational changes in conduction velocity were paralleled by significant alterations in multiple excitability parameters, similarly reaching steady values in adolescence. Maturation was accompanied by reductions in threshold (P < 0.005) and rheobase (P= 0.001); depolarizing and hyperpolarizing electrotonus progressively reduced (P < 0.001), or ‘fanned-in’; resting current–threshold slope increased (P < 0.0001); accommodation to depolarizing currents prolonged (P < 0.0001); while greater threshold changes in refractoriness (P= 0.001) and subexcitability (P < 0.01) emerged. Taken together, the present findings suggest that passive membrane conductances and the activity of K+ conductances decrease with formation of the axo-glial junction and myelination. In turn, these functional alterations serve to enhance the efficiency and speed of impulse conduction concurrent with the acquisition of motor skills during childhood, and provide unique insight into the evolution of postnatal human peripheral nerve function. Significantly, these findings bring the dynamics of axonal development to the clinical domain and serve to further illuminate pathophysiological mechanisms that occur during development. PMID:23006483

  7. The Strange Quark Polarisation from COMPASS data

    SciTech Connect

    Kouznetsov, O.

    2009-12-17

    The strange quark helicity distribution {delta}s(x) was derived at LO from the inclusive asymmetry A{sub a,d} and the semi-inclusive asymmetries A{sub 1,d}{sup {pi}}{sup +}, A{sub 1,d}{sup {pi}}{sup -}, A{sub 1,d}{sup K+}, A{sub 1,d}{sup K-}, measured by COMPASS in polarised deep inelastic muon-deuteron scattering. The distribution of {delta}s(x) is compatible with zero in the whole measured range. The value of the first moment of {delta}s and its error are very sensitive to the assumed value of the ratio of the s-bar-quark to u-quark fragmentation functions into positive kaons {integral}D(K+/s)(z)dz/{integral}D{sub u}{sup K+}(z)dz.

  8. Beyond Time-Dependent Density Functional Theory Using Only Single Excitations: Methods for Computational Studies of Excited States in Complex Systems.

    PubMed

    Herbert, John M; Zhang, Xing; Morrison, Adrian F; Liu, Jie

    2016-05-17

    Single-excitation methods, namely, configuration interaction singles and time-dependent density functional theory (TDDFT), along with semiempirical versions thereof, represent the most computationally affordable electronic structure methods for describing electronically excited states, scaling as [Formula: see text] absent further approximations. This relatively low cost, combined with a treatment of electron correlation, has made TDDFT the most widely used excited-state quantum chemistry method over the past 20+ years. Nevertheless, certain inherent problems (beyond just the accuracy of this or that exchange-correlation functional) limit the utility of traditional TDDFT. For one, it affords potential energy surfaces whose topology is incorrect in the vicinity of any conical intersection (CI) that involves the ground state. Since CIs are the conduits for transitions between electronic states, the TDDFT description of photochemistry (internal conversion and intersystem crossing) is therefore suspect. Second, the [Formula: see text] cost can become prohibitive in large systems, especially those that involve multiple electronically coupled chromophores, for example, the antennae structures of light-harvesting complexes or the conjugated polymers used in organic photovoltaics. In such cases, the smallest realistic mimics might already be quite large from the standpoint of ab initio quantum chemistry. This Account describes several new computational methods that address these problems. Topology around a CI can be rigorously corrected using a "spin-flip" version of TDDFT, which involves an α → β spin-flipping transition in addition to occupied → virtual excitation of one electron. Within this formalism, singlet states are generated via excitation from a high-spin triplet reference state, doublets from a quartet, etc. This provides a more balanced treatment of electron correlation between ground and excited states. Spin contamination is problematic away from the

  9. Excitation Function for the 74Se(18O,p3n) Reaction

    SciTech Connect

    Gates, Jacklyn; Dragojevic, Irena; Dvorak, Jan; Ellison, Paul; Gregorich, Kenneth; Stavsetra, Liv; Nitsche, Heino

    2009-02-02

    The 74Se(18O,p3n)88gNb excitation function was measured and a maximum cross section of 495+-5 mb was observed at and 18O energy of 74.0 MeV. Experimental cross sections were compared to theoretical calculations using the computer code ALICE-91 and the values were found to be in good agreement. The half life of 88gNb was determined to be around 14.56+-0.11 min.

  10. Additional Strange Hadrons from QCD Thermodynamics and Strangeness Freezeout in Heavy Ion Collisions

    NASA Astrophysics Data System (ADS)

    Bazavov, A.; Ding, H.-T.; Hegde, P.; Kaczmarek, O.; Karsch, F.; Laermann, E.; Maezawa, Y.; Mukherjee, Swagato; Ohno, H.; Petreczky, P.; Schmidt, C.; Sharma, S.; Soeldner, W.; Wagner, M.

    2014-08-01

    We compare lattice QCD results for appropriate combinations of net strangeness fluctuations and their correlations with net baryon number fluctuations with predictions from two hadron resonance gas (HRG) models having different strange hadron content. The conventionally used HRG model based on experimentally established strange hadrons fails to describe the lattice QCD results in the hadronic phase close to the QCD crossover. Supplementing the conventional HRG with additional, experimentally uncharted strange hadrons predicted by quark model calculations and observed in lattice QCD spectrum calculations leads to good descriptions of strange hadron thermodynamics below the QCD crossover. We show that the thermodynamic presence of these additional states gets imprinted in the yields of the ground-state strange hadrons leading to a systematic 5-8 MeV decrease of the chemical freeze-out temperatures of ground-state strange baryons.

  11. Maximum rotation frequency of strange stars

    SciTech Connect

    Zdunik, J.L.; Haensel, P. )

    1990-07-15

    Using the MIT bag model of strange-quark matter, we calculate the maximum angular frequency of the uniform rotation of strange stars. After studying a broad range of the MIT bag-model parameters, we obtain an upper bound of 12.3 kHz.

  12. Strangeness production with protons and pions

    SciTech Connect

    Dover, C.B.

    1993-04-01

    We discuss the spectrum of physics questions related to strangeness which could be addressed with intense beams of protons and pions in the few GeV region. We focus on various aspects of strangeness production, including hyperon production in pp collisions, studies of hyperon-nucleon scattering, production of hypernuclei in proton and pion-nucleus collisions, and spin phenomena in hypernuclei.

  13. Strangeness production with protons and pions

    SciTech Connect

    Dover, C.B.

    1993-01-01

    We discuss the spectrum of physics questions related to strangeness which could be addressed with intense beams of protons and pions in the few GeV region. We focus on various aspects of strangeness production, including hyperon production in pp collisions, studies of hyperon-nucleon scattering, production of hypernuclei in proton and pion-nucleus collisions, and spin phenomena in hypernuclei.

  14. Strangeness detection in ALICE experiment at LHC

    SciTech Connect

    Safarik, K.

    1995-07-15

    The authors present some parameters of the ALICE detector which concern the detection of strange particles. The results of a simulation for neutral strange particles and cascades, together with estimated rates are presented. They also briefly discuss the detection of charged K-mesons. Finally, they mention the possibility of open charm particle detection.

  15. QCD in Neutron Stars and Strange Stars

    SciTech Connect

    Weber, Fridolin; Negreiros, Rodrigo

    2011-05-24

    This paper provides an overview of the possible role of Quantum Chromo Dynamics (QCD) for neutron stars and strange stars. The fundamental degrees of freedom of QCD are quarks, which may exist as unconfined (color superconducting) particles in the cores of neutron stars. There is also the theoretical possibility that a significantly large number of up, down, and strange quarks may settle down in a new state of matter known as strange quark matter, which, by hypothesis, could be more stable than even the most stable atomic nucleus, {sup 56}Fe. In the latter case new classes of self-bound, color superconducting objects, ranging from strange quark nuggets to strange quark stars, should exist. The properties of such objects will be reviewed along with the possible existence of deconfined quarks in neutron stars. Implications for observational astrophysics are pointed out.

  16. The Maximum Mass of Rotating Strange Stars

    NASA Astrophysics Data System (ADS)

    Szkudlarek, M.; Gondek-Rosiń; ska, D.; Villain, L.; Ansorg, M.

    2012-12-01

    Strange quark stars are considered as a possible alternative to neutron stars as compact objects (e.g. Weber 2003). A hot compact star (a proto-neutron star or a strange star) born in a supernova explosion or a remnant of neutron stars binary merger are expected to rotate differentially and be important sources of gravitational waves. We present results of the first relativistic calculations of differentially rotating strange quark stars for broad ranges of degree of differential rotation and maximum densities. Using a highly accurate, relativistic code we show that rotation may cause a significant increase of maximum allowed mass of strange stars, much larger than in the case of neutron stars with the same degree of differential rotation. Depending on the maximum allowed mass a massive neutron star (strange star) can be temporarily stabilized by differential rotation or collapse to a black hole.

  17. Strange musical rhythms.

    PubMed

    Valentinuzzi, Max E; Hortt, Federico

    2014-01-01

    Music, along with its attached rhythm, has been with man for centuries, developing and evolving along with him. Its influence on human behavior and mood can reach levels whose limits are still unknown, especially in everything related to perception, where the whole nervous system is involved. Thus, physiology and psychology become strongly connected areas, while technology, through, for example, the production of music by electronic means, appears as a new unexpected ingredient that traditional composers and musicians of older times could not imagine. Obviously, bioengineering and its multiple branches are not absent either [1]?[4]. The literature is enormous with several specialized journals. When one looks back in time at the evolution of this complex area, the appearance of some kind of sudden jump (as a step function), which took place within a relatively recent short interval, is evident: music is now much more than what it used to be, and rhythm has made a step forward as if resurrecting and renewing the ancient Indian or African drums. PMID:25437475

  18. Measurement of excitation functions in alpha-induced reactions on yttrium

    NASA Astrophysics Data System (ADS)

    Shahid, Muhammad; Kim, Kwangsoo; Naik, Haladhara; Zaman, Muhammad; Kim, Guinyun; Yang, Sung-Chul; Song, Tae-Young

    2015-01-01

    The excitation functions of 89g,m,90,91m,92mNb,88,89Zr, and 87g,m,88,90m,91mY from alpha-induced reactions on 89Y were measured from their respective threshold to 45 MeV by using a stacked-foil activation technique at the MC-50 cyclotron of the Korean Institute of Radiological and Medical Sciences. The results were compared with the earlier reported data as well as with the theoretical values obtained from the TENDL-2013 library based on the TALYS1.6 code. Our measurements in the energy region from the threshold energy to 45 MeV are in general good agreement with the other experimental data and calculated results. The integral yields for thick target of the produced radionuclides were also deduced from their measured cross sections and the stopping power of 89Y. The measured excitation functions find importance in various practical applications including nuclear medicine and improvement of nuclear model calculations.

  19. Comparison between Theoretical Calculation and Experimental Results of Excitation Functions for Production of Relevant Biomedical Radionuclides

    NASA Astrophysics Data System (ADS)

    Menapace, E.; Birattari, C.; Bonardi, M. L.; Groppi, F.; Morzenti, S.; Zona, C.

    2005-05-01

    The radionuclide production for biomedical applications has been brought up in the years, as a special nuclear application, at INFN LASA Laboratory, particularly in co-operation with the JRC-Ispra of EC. Mainly scientific aspects concerning radiation detection and the relevant instruments, the measurements of excitation functions of the involved nuclear reactions, the requested radiochemistry studies and further applications have been investigated. On the side of the nuclear data evaluations, based on nuclear model calculations and critically selected experimental data, the appropriate competence has been developed at ENEA Division for Advanced Physics Technologies. A series of high specific activity accelerator-produced radionuclides in no-carrier-added (NCA) form, for uses in metabolic radiotherapy and for PET radiodiagnostics, are investigated. In this work, last revised measurements and model calculations are reviewed for excitation functions of natZn(d,X)64Cu, 66Ga reactions, referring to irradiation experiments at K=38 variable energy Cyclotron of JRC-Ispra. Concerning the reaction data for producing 186gRe and 211At/211gPo (including significant emission spectra) and 210At, most recent and critically selected experimental results are considered and discussed in comparison with model calculations paying special care to pre-equilibrium effects estimate and to the appropriate overall parameterization. Model calculations are presented for 226Ra(p,2n)225Ac reaction, according to the working program of the ongoing IAEA CRP on the matter.

  20. Excitation function of elastic pp scattering from a unitarily extended Bialas-Bzdak model

    NASA Astrophysics Data System (ADS)

    Nemes, F.; Csörgő, T.; Csanád, M.

    2015-05-01

    The Bialas-Bzdak model of elastic proton-proton scattering assumes a purely imaginary forward scattering amplitude, which consequently vanishes at the diffractive minima. We extended the model to arbitrarily large real parts in a way that constraints from unitarity are satisfied. The resulting model is able to describe elastic pp scattering not only at the lower ISR energies but also at √ {s} = 7 TeV in a statistically acceptable manner, both in the diffractive cone and in the region of the first diffractive minimum. The total cross-section as well as the differential cross-section of elastic proton-proton scattering is predicted for the future LHC energies of √ {s} = 13, 14, 15 TeV and also to 28 TeV. A nontrivial, significantly nonexponential feature of the differential cross-section of elastic proton-proton scattering is analyzed and the excitation function of the nonexponential behavior is predicted. The excitation function of the shadow profiles is discussed and related to saturation at small impact parameters.

  1. Comparison between Theoretical Calculation and Experimental Results of Excitation Functions for Production of Relevant Biomedical Radionuclides

    SciTech Connect

    Menapace, E.; Birattari, C.; Bonardi, M.L.; Groppi, F.; Morzenti, S.; Zona, C.

    2005-05-24

    The radionuclide production for biomedical applications has been brought up in the years, as a special nuclear application, at INFN LASA Laboratory, particularly in co-operation with the JRC-Ispra of EC. Mainly scientific aspects concerning radiation detection and the relevant instruments, the measurements of excitation functions of the involved nuclear reactions, the requested radiochemistry studies and further applications have been investigated. On the side of the nuclear data evaluations, based on nuclear model calculations and critically selected experimental data, the appropriate competence has been developed at ENEA Division for Advanced Physics Technologies. A series of high specific activity accelerator-produced radionuclides in no-carrier-added (NCA) form, for uses in metabolic radiotherapy and for PET radiodiagnostics, are investigated. In this work, last revised measurements and model calculations are reviewed for excitation functions of natZn(d,X)64Cu, 66Ga reactions, referring to irradiation experiments at K=38 variable energy Cyclotron of JRC-Ispra. Concerning the reaction data for producing 186gRe and 211At/211gPo (including significant emission spectra) and 210At, most recent and critically selected experimental results are considered and discussed in comparison with model calculations paying special care to pre-equilibrium effects estimate and to the appropriate overall parameterization. Model calculations are presented for 226Ra(p,2n)225Ac reaction, according to the working program of the ongoing IAEA CRP on the matter.

  2. Visualization of molecular fluorescence point spread functions via remote excitation switching fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Su, Liang; Lu, Gang; Kenens, Bart; Rocha, Susana; Fron, Eduard; Yuan, Haifeng; Chen, Chang; van Dorpe, Pol; Roeffaers, Maarten B. J.; Mizuno, Hideaki; Hofkens, Johan; Hutchison, James A.; Uji-I, Hiroshi

    2015-02-01

    The enhancement of molecular absorption, emission and scattering processes by coupling to surface plasmon polaritons on metallic nanoparticles is a key issue in plasmonics for applications in (bio)chemical sensing, light harvesting and photocatalysis. Nevertheless, the point spread functions for single-molecule emission near metallic nanoparticles remain difficult to characterize due to fluorophore photodegradation, background emission and scattering from the plasmonic structure. Here we overcome this problem by exciting fluorophores remotely using plasmons propagating along metallic nanowires. The experiments reveal a complex array of single-molecule fluorescence point spread functions that depend not only on nanowire dimensions but also on the position and orientation of the molecular transition dipole. This work has consequences for both single-molecule regime-sensing and super-resolution imaging involving metallic nanoparticles and opens the possibilities for fast size sorting of metallic nanoparticles, and for predicting molecular orientation and binding position on metallic nanoparticles via far-field optical imaging.

  3. Characteristic Features of Strangeness Nuclear Systems

    NASA Astrophysics Data System (ADS)

    Akaishi, Yoshinori

    2001-10-01

    The Λ-Σ coupling is one of the most characteristic dynamics in hypernuclear physics, since the Σ-Λ mass difference is muc h smaller than Δ-N one. The coupling can be divided into coherent and incoheren t parts. The suppression of the incoherent part solves a long-standing problem of Λ-overbinding in ^5_ΛHe but it, in turn, causes an un derbinding problem in ^4_ΛHe. This shortage is overcome by the coherent cou pling which is equivalently expressed by a ΛNN three-body force. The three-body force has a large effect exclusively on the 0^+ state of ^4_ΛHe among s-shell hypernuclei according to coherently added enhancement. The coherent coupling explains also the ^4_ΣHe spectrum recently observed at BNL. In dense neutron matter the coherent Λ-Σ coupling causes strong Σ^0 admixture of 5 ~25 % at ρ=ρ0 ~ 3ρ0 where Λ and Σ^0 components are mixed up as one particle Λ_coh. This coherent mixing drastically affects the hyperon composition of neutron-star matter. One of the most important but yet unsolved problems is how the hadron property changes in nuclear medium. In strangeness sector, this problem is connected to an exciting issue of kao n condensation. Recently Akaishi and Yamazaki predicted that nuclear barK bound sta tes possibly exist in ^3He and ^4He with large binding energies of 108 MeV and of 86 MeV and narrow widths of 20 MeV and of 34 MeV, respectively. The formation of deeply-bound barK nuclear states in He and Be gives a new means to investigate hadron properties in cold high-density nucl ear medium because barK strongly contracts the core nuclei. Observation of such barK nuclear states would provide information of fundamental importance in relation to strangeness condensation.

  4. The Strange Quark Polarisation from Charged Kaon Production on Deuterons

    SciTech Connect

    Windmolders, R.

    2009-08-04

    The strange quark helicity distribution {delta}s(x) is derived at LO from the semi-inclusive and inclusive spin asymmetries measured by the COMPASS experiment at CERN. The significance of the results is found to depend critically on the ratio of the s-bar and u quark fragmentation functions into kaons {integral}D{sub s-bar}{sup K+}(z)dz/{integral}D{sub u}{sup K+}(z)dz.

  5. Excitation spectra and correlation functions of quantum Su-Schrieffer-Heeger models

    NASA Astrophysics Data System (ADS)

    Weber, Manuel; Assaad, Fakher F.; Hohenadler, Martin

    2015-06-01

    We study one-dimensional Su-Schrieffer-Heeger (SSH) models with quantum phonons using a continuous-time quantum Monte Carlo method. Within statistical errors, we obtain identical results for the SSH model with acoustic phonons, and a related model with a coupling to an optical bond phonon mode. Based on this agreement, we first study the Peierls metal-insulator transition of the spinless SSH model, and relate it to the Kosterlitz-Thouless transition of a spinless Luttinger liquid. In the Peierls phase, the spectral functions reveal the single-particle and charge gap, and a central peak related to long-range order. For the spinful SSH model, which has a dimerized ground state for any nonzero coupling, we reveal a symmetry-related degeneracy of spin and charge excitations, and the expected spin and charge gaps as well as a central peak. Finally, we study the SSH-U V model with electron-phonon and electron-electron interaction. We observe a Mott phase with critical spin and bond correlations at weak electron-phonon coupling, and a Peierls phase with gapped spin excitations at strong coupling. We relate our findings to the extended Hubbard model, and discuss the physical origin of the agreement between optical and acoustic phonons.

  6. Spin contamination-free N-electron wave functions in the excitation-based configuration interaction treatment

    NASA Astrophysics Data System (ADS)

    Alcoba, Diego R.; Torre, Alicia; Lain, Luis; Massaccesi, Gustavo E.; Oña, Ofelia B.; Capuzzi, Pablo

    2016-07-01

    This work deals with the spin contamination in N-electron wave functions provided by the excitation-based configuration interaction methods. We propose a procedure to ensure a suitable selection of excited N-electron Slater determinants with respect to a given reference determinant, required in these schemes. The procedure guarantees the construction of N-electron wave functions which are eigenfunctions of the spin-squared operator S ˆ 2 , avoiding any spin contamination. Our treatment is based on the evaluation of the excitation level of the determinants by means of the expectation value of an excitation operator formulated in terms of spin-free replacement operators. We report numerical determinations of energies and < S ˆ 2 > expectation values, arising from our proposal as well as from traditional configuration interaction methods, in selected open-shell systems, in order to compare the behavior of these procedures and their computational costs.

  7. Spin contamination-free N-electron wave functions in the excitation-based configuration interaction treatment.

    PubMed

    Alcoba, Diego R; Torre, Alicia; Lain, Luis; Massaccesi, Gustavo E; Oña, Ofelia B; Capuzzi, Pablo

    2016-07-01

    This work deals with the spin contamination in N-electron wave functions provided by the excitation-based configuration interaction methods. We propose a procedure to ensure a suitable selection of excited N-electron Slater determinants with respect to a given reference determinant, required in these schemes. The procedure guarantees the construction of N-electron wave functions which are eigenfunctions of the spin-squared operator Sˆ(2), avoiding any spin contamination. Our treatment is based on the evaluation of the excitation level of the determinants by means of the expectation value of an excitation operator formulated in terms of spin-free replacement operators. We report numerical determinations of energies and 〈Sˆ(2)〉 expectation values, arising from our proposal as well as from traditional configuration interaction methods, in selected open-shell systems, in order to compare the behavior of these procedures and their computational costs. PMID:27394101

  8. Constraining the high-density behavior of the nuclear equation of state from strangeness production in heavy-ion collisions

    SciTech Connect

    Feng Zhaoing

    2011-06-15

    The dynamics of pions and strange particles in heavy-ion collisions in the region of 1A GeV energies is investigated by the lanzhou quantum molecular dynamics model for probing the nuclear equation of state at suprasaturation densities. The total multiplicities and the ratios obtained in {sup 197}Au+{sup 197}Au over {sup 12}C+{sup 12}C systems are calculated for selected Skyrme parameters SkP, SLy6, Ska, and SIII, which correspond to different modulus of incompressibility of symmetric nuclear matter and different cases of the stiffness of symmetry energy. A decreasing trend of the excitation functions of the ratios for strange particle production with increasing incident energy was observed. The available data of K{sup +} production measured by KaoS collaboration are described well with the parameter SkP, which results in a soft equation of state. The conclusions cannot be modified by an in-medium kaon-nucleon potential.

  9. Strange particle production and s-quark asymmetry

    SciTech Connect

    Narita, S.

    1996-08-01

    Using hadronic Z{sup 0} decays recorded by the SLD experiment at SLAC, we have studied the production of strange particles as a function of momentum. A high-purity sample of K{sup {+-}} was tagged using Cherenkov Ring Imaging Detector (CRID). The {phi}, {Lambda} and K{sub s} were reconstructed in the K{sup +}K{sup -}, p-{pi} and {pi}{sup +}{pi}{sup -} modes respectively, and CRID identification of K{sup {+-}} and p was used to obtain pure samples of {phi} and {Lambda}. We have used the high electron-beam polarisation delivered by the SLC to measure the left-right forward-backward production asymmetries of these particles, and discuss the relationship of these quantities to the underlying strange quark asymmetry in Z{sup 0} decays.

  10. The strange beauty of the proton

    NASA Astrophysics Data System (ADS)

    Bijker, Roelof; Ferretti, Jacopo; Santopinto, Elena

    2012-10-01

    The contribution of strange quarks to the proton is addressed in two different models of the nucleon, a phenomenological two-component model in which the nucleon is described in terms of an intrinsic three-quark structure surrounded by a meson cloud, and the unquenched quark model in which the effects of the sea quarks are taken into account through a 3P0 quark-antiquark pair creation mechanism. The results for the strange magnetic moment and the strangeness radius of the proton are found to be small, in agreement with the latest experimental results from parity-violating electron scattering and recent lattice calculations.

  11. Proton and deuteron induced reactions on natGa: Experimental and calculated excitation functions

    NASA Astrophysics Data System (ADS)

    Hermanne, A.; Adam-Rebeles, R.; Tárkányi, F.; Takács, S.; Ditrói, F.

    2015-09-01

    Cross-sections for reactions on natGa, induced by protons (up to 65 MeV) and deuterons (up to 50 MeV), producing γ-emitting radionuclides with half-lives longer than 1 h were measured in a stacked-foil irradiation using thin Ga-Ni alloy (70-30%) targets electroplated on Cu or Au backings. Excitation functions for generation of 68,69Ge, 66,67,68,72Ga and 65,69mZn on natGa are discussed, relative to the monitor reactions natAl(d,x)24,22Na, natAl(p,x)24,22Na, natCu(p,x)62Zn and natNi(p,x)57Ni. The results are compared to our earlier measurements, the scarce literature values and to the results of the code TALYS 1.6 (online database TENDL-2014).

  12. Excited electronic states of MnO4-: Challenges for wavefunction and density functional response theories

    NASA Astrophysics Data System (ADS)

    Almeida, Nuno M. S.; McKinlay, Russell G.; Paterson, Martin J.

    2015-01-01

    The lowest excited electronic states of the permanganate ion MnO4- are calculated using a hierarchy of coupled cluster response approaches, as well as time-dependent density functional theory. It is shown that while full linear response coupled cluster with singles and doubles (or higher) performs well, that permanganate represents a stern test for approximate coupled cluster response models, and that problems can be traced to very large orbital relaxation effects. TD-DFT is reasonably robust although errors around 0.6 eV are still observed. In order to further investigate the strong correlations prevalent in the electronic ground state large-scale RASSCF calculations were also performed. Again very large orbital relaxation in the correlated wavefunction is observed. Although the system can qualitatively be described by a single configuration, multi-reference diagnostic values show that care must be taken in this and similar metal complexes.

  13. Excitation functions of parameters in Erlang distribution, Schwinger mechanism, and Tsallis statistics in RHIC BES program

    NASA Astrophysics Data System (ADS)

    Gao, Li-Na; Liu, Fu-Hu; Lacey, Roy A.

    2016-05-01

    Experimental results of the transverse-momentum distributions of φ mesons and Ω hyperons produced in gold-gold (Au-Au) collisions with different centrality intervals, measured by the STAR Collaboration at different energies (7.7, 11.5, 19.6, 27, and 39 GeV) in the beam energy scan (BES) program at the relativistic heavy-ion collider (RHIC), are approximately described by the single Erlang distribution and the two-component Schwinger mechanism. Moreover, the STAR experimental transverse-momentum distributions of negatively charged particles, produced in Au-Au collisions at RHIC BES energies, are approximately described by the two-component Erlang distribution and the single Tsallis statistics. The excitation functions of free parameters are obtained from the fit to the experimental data. A weak softest point in the string tension in Ω hyperon spectra is observed at 7.7 GeV.

  14. The use of coherence functions to determine dynamic excitation sources on launch vehicle payloads

    NASA Technical Reports Server (NTRS)

    Barrett, S.; Halvorson, R. M.

    1979-01-01

    The problem of determining the relative contribution of simultaneous acoustic and mechanical inputs to the response of structures under combined dynamic loads was studied. An analytical technique developed by Bendat for calculating ordinary, partial, and multiple coherence functions, using an iterative nonmatrix approach was applied to data obtained from laboratory tests on a complex structural assembly. Testing was performed in an acoustically 'live' room. Up to three random inputs, having similar spectral content and varying degrees of mutual coherence, and a single output were used. Stationary and nonstationary inputs were used. It was concluded that the technique provided an effective method of identifying sources of dynamic excitation and evaluating their relative contributions to the measured output at structural resonances, for stationary random inputs. An attempt to apply the technique to nonstationary inputs did not yield consistent results.

  15. Excitation function of (3)He-particle induced nuclear reactions on natural palladium.

    PubMed

    Al-Abyad, M; Tárkányi, F; Ditrói, F; Takács, S

    2014-12-01

    Excitation functions of (3)He-particle induced nuclear reactions on natural palladium were measured using the standard stacked foil technique and high resolution γ-ray spectroscopy. From their threshold energies up to 27MeV, cross-sections for (nat)Pd((3)He,x)(103,104,105,106m,110m,111,112)Ag and (nat)Pd((3)He,x)(104,105,107,111m)Cd reactions were measured. The nuclear model codes TALYS-1.4, and EMPIRE-3.1 were used to describe the formation of these products. The present data were compared to theoretical results and to the available experimental data. Integral yields for some important radioisotopes were determined. PMID:25218461

  16. Effects of intrinsic degrees of freedom in enhancement of sub-barrier fusion excitation function data

    NASA Astrophysics Data System (ADS)

    Gautam, Manjeet Singh

    2015-02-01

    This paper is mainly focused on the limitations of energy independent Woods-Saxon potential and the applicability of energy dependent Woods-Saxon potential (EDWSP) model in conjunction with one-dimensional Wong formula for description of the heavy-ion fusion reactions. The effects of neutron transfer channels and inelastic surface vibrations of colliding nuclei in the enhancement of sub-barrier fusion excitation function data, in the various heavy-ion fusion reactions, have been investigated within the framework of energy independent one-dimensional barrier penetration model, the EDWSP model and the coupled channel code CCFULL. In certain projectile-target combinations, the influences of multi-neutrons transfer between reactants are found to be dominating over the coupling to low lying surface vibrational states. Furthermore, the effects of these dominant degrees of freedom can be simulated by introducing the energy dependence in real part of nucleus-nucleus potential.

  17. Penta-Quark States with Strangeness, Hidden Charm and Beauty

    NASA Astrophysics Data System (ADS)

    Wu, Jia-Jun; Zou, Bing-Song

    The classical quenched quark models with three constituent quarks provide a good description for the baryon spatial ground states, but fail to reproduce the spectrum of baryon excited states. More and more evidences suggest that unquenched effects with multi-quark dynamics are necessary ingredients to solve the problem. Several new hyperon resonances reported recently could fit in the picture of penta-quark states. Based on this picture, some new hyperon excited states were predicted to exist; meanwhile with extension from strangeness to charm and beauty, super-heavy narrow N* and Λ* resonances with hidden charm or beauty were predicted to be around 4.3 and 11 GeV, respectively. Recently, two of such N* with hidden charm might have been observed by the LHCb experiment. More of those states are expected to be observed in near future. This opens a new window in order to study hadronic dynamics for the multi-quark states.

  18. The Electron Excitation Function of H Lyman-(alpha) from Threshold to 1.8 keV

    NASA Technical Reports Server (NTRS)

    James, G. K.; Slevin, J. A.; Shemansky, D. E.; McConkey, J. W.; Dziczek, D.; Kanik, I.; Ajello, J. M.

    1996-01-01

    The excitation function of prompt Lyman-(alpha) radiation, produced by electron impact excitation of atomic hydrogen, has been measured for the first time over an extended energy range from threshold to 1.8 keV. Measurments were obtained in a crossed-beams experiment using both magnetically confined and electrostatically focused electrons in collision with atomic hydrogen produced by an intense discharge source.

  19. On the possibility of measuring the strange-valence-quark distribution of the kaon and the strange-sea distribution of the proton in Drell-Yan processes

    SciTech Connect

    Badalyan, R.G.; Gulkanyan, G.R. )

    1989-07-01

    We show that the combined investigations of inclusive and semi-inclusive (registering the accompanying tagged pion) of Drell-Yan lepton-pair production processes in K{sup +}p and K{sup {minus}}p interactions makes it possible to measure the valence part of the kaon structure functions, the strange-sea distribution in the proton, and also the fragmentation function into pions of multiparton states formed in the kaon fragmentation region as a result of the annihilation of a valence quark (strange or nonstrange). In the framework of the recombination model of hadron production we predict differential cross sections of semi-inclusive Drell-Yan processes.

  20. Theoretical perspectives on strange physics

    NASA Astrophysics Data System (ADS)

    Ellis, J.

    1983-04-01

    Kaons are heavy enough to have an interesting range of decay modes available to them, and light enough to be produced in sufficient numbers to explore rate modes with satisfying statistics. Kaons and their decays have provided at least two major breakthroughs in fundamental physics: CP violation, and their lack of flavor-changing neutral interactions warned us to expect charm. In addition, K0-anti K0 mixing has provided one of the most elegant and sensitive laboratories for testing quantum mechanics. There is every reason to expect that future generations of kaon experiments with intense sources would add further to fundamental physics. This talk attempts to set future kaon experiments in a general theoretical context, and indicate how they bear upon fundamental theoretical issues. A survey of different experiments which would be done with an Intense Medium Energy Source of Strangeness, including rare K decays, probes of the nature of CP isolation, (SIGMA) decays, hyperon decays and neutrino physics is given.

  1. Strangeness production in PHENIX experiment

    NASA Astrophysics Data System (ADS)

    Kotov, D. O.

    2016-01-01

    The PHENIX experiment at RHIC has measured production of K±, Ks, K* and ϕmesons in p+p, d+Au, Cu+Cu and Au+Au collisions at √sNN = 62.4 and 200 GeV. While p+p collisions provide a baseline and are used for precision tests of pQCD calculations, for heavier colliding systems such as d+Au, Cu+Cu and Au+Au nuclear modification factors are studied at different centralities. These systematic studies enrich current understanding of the strange meson production and its difference from light quark hadrons. The role of radial flow and coalescence in particle production is discussed.

  2. A multireference density functional approach to the calculation of the excited states of uranium ions

    NASA Astrophysics Data System (ADS)

    Beck, Eric V.

    An accurate and efficient hybrid Density Functional Theory (DFT) and Multireference Configuration Interaction (MRCI) model for computing electronic excitation energies in atoms and molecules was developed. The utility of a hybrid method becomes apparent when ground and excited states of large molecules, clusters of molecules, or even moderately sized molecules containing heavy element atoms are desired. In the case of large systems of lighter elements, the hybrid method brings to bear the numerical efficiency of the DFT method in computing the electron-electron dynamic correlation, while including non-dynamical electronic correlation via the Configuration Interaction (CI) calculation. Substantial reductions in the size of the CI expansion necessary to obtain accurate spectroscopic results are possible in the hybrid method. Where heavy element compounds are of interest, fully relativistic calculations based upon the Dirac Hamiltonian rapidly become computationally prohibitive, as the basis set requirements in four-component calculations increase by a factor of two or more in order to satisfy kinetic balance between the large electronic components and small positronic components, while the size of the MRCI Hamiltonian quadruples with respect to a non-relativistic calculation. In this hybrid method, applications to heavy element compounds such as bromine and uranium were accomplished through the use of relativistic effective core potentials, allowing for the first time both scalar relativistic and spin-orbit effect treatment necessary for the accurate calculation of electronic excitation energies in heavy elements in a Density Functional Theory Multireference Configuration Interaction Hybrid Model (DFT/MRCI) method. This implementation of the original hybrid method, developed by Grimme and Waletzke, was modified to remove inherent spin-multiplicity limitations, as well as reduce the number of free parameters used in the method from five to three. The DFT portion of

  3. Strangeness suppression in the unquenched quark model

    NASA Astrophysics Data System (ADS)

    Bijker, Roelof; García-Tecocoatzi, Hugo; Santopinto, Elena

    2016-07-01

    In this contribution, we discuss the strangeness suppression in the proton in the framework of the unquenched quark model. The theoretical results are in good agreement with the values extracted from CERN and JLab experiments.

  4. Strange Creatures: An Additive Wood Sculpture Project.

    ERIC Educational Resources Information Center

    Wales, Andrew

    2002-01-01

    Describes an art project where students create strange creatures using scraps of wood. Discusses how the students use the wood and other materials. Explains that the students also write about the habitat characteristics of their creatures. Includes learning objectives. (CMK)

  5. Strange quark matter fragmentation in astrophysical events

    NASA Astrophysics Data System (ADS)

    Paulucci, L.; Horvath, J. E.

    2014-06-01

    The conjecture of Bodmer-Witten-Terazawa suggesting a form of quark matter (Strange Quark Matter) as the ground state of hadronic interactions has been studied in laboratory and astrophysical contexts by a large number of authors. If strange stars exist, some violent events involving these compact objects, such as mergers and even their formation process, might eject some strange matter into the interstellar medium that could be detected as a trace signal in the cosmic ray flux. To evaluate this possibility, it is necessary to understand how this matter in bulk would fragment in the form of strangelets (small lumps of strange quark matter in which finite effects become important). We calculate the mass distribution outcome using the statistical multifragmentation model and point out several caveats affecting it. In particular, the possibility that strangelets fragmentation will render a tiny fraction of contamination in the cosmic ray flux is discussed.

  6. Molecular Excitation Energies from Time-Dependent Density Functional Theory Employing Random-Phase Approximation Hessians with Exact Exchange.

    PubMed

    Heßelmann, Andreas

    2015-04-14

    Molecular excitation energies have been calculated with time-dependent density-functional theory (TDDFT) using random-phase approximation Hessians augmented with exact exchange contributions in various orders. It has been observed that this approach yields fairly accurate local valence excitations if combined with accurate asymptotically corrected exchange-correlation potentials used in the ground-state Kohn-Sham calculations. The inclusion of long-range particle-particle with hole-hole interactions in the kernel leads to errors of 0.14 eV only for the lowest excitations of a selection of three alkene, three carbonyl, and five azabenzene molecules, thus surpassing the accuracy of a number of common TDDFT and even some wave function correlation methods. In the case of long-range charge-transfer excitations, the method typically underestimates accurate reference excitation energies by 8% on average, which is better than with standard hybrid-GGA functionals but worse compared to range-separated functional approximations. PMID:26574370

  7. Strange Attractors in Drift Wave Turbulence

    SciTech Connect

    J.L.V. Lewandowski

    2003-04-25

    A multi-grid part-in-cell algorithm for a shearless slab drift wave model with kinetic electrons is presented. The algorithm, which is based on an exact separation of adiabatic and nonadiabatic electron responses, is used to investigate the presence of strange attractors in drift wave turbulence. Although the simulation model has a large number of degrees of freedom, it is found that the strange attractor is low-dimensional and that it is strongly affected by dissipative (collisional) effects.

  8. A New Method To Evaluate Excited States Lifetimes Based on Green's Function: Application to Dye-Sensitized Solar Cells.

    PubMed

    Sulzer, David; Iuchi, Satoru; Yasuda, Koji

    2016-07-12

    Dye-sensitized solar cell (DSSCs) are the promising device for electricity generation. However, the initial stage in which an electron is injected from a dye to the semiconductor has not been precisely understood. Standard quantum chemistry methods cannot handle infinite number of orbitals coming from the band structure of the semiconductor, whereas solid state calculations cannot handle many excited states at a reasonable computational cost. In this regard, we propose a new method to evaluate lifetimes of many excited states of a molecule on a semi-infinite surface. On the basis of the theory of resonance state, the effect of the semi-infinite semiconductor is encoded into the complex self-energy from surface Green's function. The lifetimes of excited states are evaluated through the imaginary part of the self-energy, and the self-energy correction is included into excitation energies obtained from time-dependent density functional theory calculations. This new method is applied to a DSSC system composed of black dye attached to the TiO2 semiconductor, and the computed lifetimes are linked to the natures of excited states and to the surface properties. The present method provides the firm ground for analysis of interplay between many excited states of the dye and band structure of the semiconductor. PMID:27310524

  9. Obtaining Hartree-Fock and density functional theory doubly excited states with Car-Parrinello density matrix search

    NASA Astrophysics Data System (ADS)

    Liang, Wenkel; Isborn, Christine M.; Li, Xiaosong

    2009-11-01

    The calculation of doubly excited states is one of the major problems plaguing the modern day excited state workhorse methodology of linear response time dependent Hartree-Fock (TDHF) and density function theory (TDDFT). We have previously shown that the use of a resonantly tuned field within real-time TDHF and TDDFT is able to simultaneously excite both the α and β electrons to achieve the two-electron excited states of minimal basis H2 and HeH+ [C. M. Isborn and X. Li, J. Chem. Phys. 129, 204107 (2008)]. We now extend this method to many electron systems with the use of our Car-Parrinello density matrix search (CP-DMS) with a first-principles fictitious mass method for wave function optimization [X. Li, C. L. Moss, W. Liang, and Y. Feng, J. Chem. Phys. 130, 234115 (2009)]. Real-time TDHF/TDDFT is used during the application of the laser field perturbation, driving the electron density toward the doubly excited state. The CP-DMS method then converges the density to the nearest stationary state. We present these stationary state doubly excited state energies and properties at the HF and DFT levels for H2, HeH+, lithium hydride, ethylene, and butadiene.

  10. Dimensionality of electronic excitations in organic semiconductors: A dielectric function approach

    NASA Astrophysics Data System (ADS)

    Campoy-Quiles, Mariano; Nelson, Jenny; Bradley, Donal D. C.; Etchegoin, Pablo G.

    2007-12-01

    We present a detailed investigation on the effective dimensionality (associated with the degree of delocalization) of electronic excitations in thin organic films using the dielectric function as obtained from ellipsometry. To this end, we study first the best analytical representation of the optical dielectric function of these materials and compare different approaches found in the literature: (i) the harmonic oscillator approximation, (ii) the standard critical-point model (SCP), (iii) the model dielectric function (MDF), and (iv) the Forouhi-Bloomer model. We use these models to analyze variable angle spectroscopic ellipsometry raw data for a thin poly(9,9-dioctylfluorene) (PFO) film deposited on quartz (taken as an archetypal sample). The superiority of the SCP model for PFO films and a wide range of other spin-coated conjugated polymers (and guest-molecules in polymers) is demonstrated. Moreover, we show how the SCP model can be used to gain physical information on the microscopic structure. As an example, we show that the delocalization of excitons decreases for nonconjugated polymers, such as polymethylmethacrylate and polyimide, while the conjugation length and exciton delocalization are, respectively, enhanced in cases where a planar conformation (e.g., β phase of PFO) or a high degree of crystallinity [e.g., poly(3-hexylthiophene)] is achieved. As an additional example, we employ the SCP excitonic model to investigate the temperature dependence of the dielectric function of crystalline and glassy PFO films. We propose that the SCP excitonic model should be adopted as the standard choice to model the optical properties of polymer thin films from ellipsometry data.

  11. Calculation of excitation functions of proton, alpha and deuteron induced reactions for production of medical radioisotopes 122-125I

    NASA Astrophysics Data System (ADS)

    Artun, Ozan; Aytekin, Hüseyin

    2015-02-01

    In this work, the excitation functions for production of medical radioisotopes 122-125I with proton, alpha, and deuteron induced reactions were calculated by two different level density models. For the nuclear model calculations, the Talys 1.6 code were used, which is the latest version of Talys code series. Calculations of excitation functions for production of the 122-125I isotopes were carried out by using the generalized superfluid model (GSM) and Fermi-gas model (FGM). The results have shown that generalized superfluid model is more successful than Fermi-gas model in explaining the experimental results.

  12. Strange quark suppression and strange hadron production in pp collisions at energies available at the BNL Relativistic Heavy Ion Collider and the CERN Large Hadron Collider

    SciTech Connect

    Long Haiyan; Feng Shengqin; Zhou Daimei; Yan Yuliang; Ma Hailiang; Sa Benhao

    2011-09-15

    The parton and hadron cascade model PACIAE based on PYTHIA is utilized to systematically investigate strange particle production in pp collisions at energies available at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC). Globally speaking, the PACIAE results of the strange particle rapidity density at midrapidity and the transverse momentum distribution are better than those of PYTHIA (default) in comparison with STAR and ALICE experimental data. This may represent the importance of the parton and hadron rescatterings, as well as the reduction mechanism of strange quark suppression, added in the PACIAE model. The K/{pi} ratios as a function of reaction energy in pp collisions from CERN Super Proton Synchrotron (SPS) to LHC energies are also analyzed in this paper.

  13. On the resonance energy of the strange dibaryon

    SciTech Connect

    Yoichi Ikeda, Hiroyuki Kamano, Toru Sato

    2010-03-01

    The three-body resonance energies of the strange dibaryon are studied with the View the MathML source coupled-channels Faddeev equations. Our resonance energies are compared with those of an effective potential approach (EPA), where a coupling to the πYN channel is simulated by an effective View the MathML source potential, and the spectator momentum in the πYN Green function is neglected. About a 30% reduction of the binding energies due to neglecting the spectator momentum in the πYN Green's function is observed.

  14. Strangeness Production at Jefferson Lab

    SciTech Connect

    Raue, Brian

    2003-11-01

    The Thomas Jefferson National Accelerator Facility has an extensive program of studying the electromagnetic production of strange particles. One of the main components of this program has been the study of both photo- and electropro- duction of K+ + â º0 and K+ + Å 0 final states. Experiments are being, or have been conducted in all three of Jefferson Lab s experimental halls measuring a wide range of observables at kinematics from threshold up to W H 3.0 GeV and Q2 from 0.4 up to 5 (GeV/c)2. The largest effort in this endeavor is taking place in Hall B using the CEBAF Large Acceptance Spectrometer (CLAS). Data have been taken at about ten different polarized electron beam energies and are currently being analyzed. Preliminary results [1] for one beam energy exist wherein the unpolarized cross section has been separated into three components: AT + eLAL, ATT , and ALT . The data indicate a t-channel dominance for the â º0 production and a strong s-channel dominance for Å 0 produc

  15. Theoretical perspectives on strange physics

    SciTech Connect

    Ellis, J.

    1983-04-01

    Kaons are heavy enough to have an interesting range of decay modes available to them, and light enough to be produced in sufficient numbers to explore rare modes with satisfying statistics. Kaons and their decays have provided at least two major breakthroughs in our knowledge of fundamental physics. They have revealed to us CP violation, and their lack of flavor-changing neutral interactions warned us to expect charm. In addition, K/sup 0/-anti K/sup 0/ mixing has provided us with one of our most elegant and sensitive laboratories for testing quantum mechanics. There is every reason to expect that future generations of kaon experiments with intense sources would add further to our knowledge of fundamental physics. This talk attempts to set future kaon experiments in a general theoretical context, and indicate how they may bear upon fundamental theoretical issues. A survey of different experiments which would be done with an Intense Medium Energy Source of Strangeness, including rare K decays, probes of the nature of CP isolation, ..mu.. decays, hyperon decays and neutrino physics is given. (WHK)

  16. Design and optimization for variable rate selective excitation using an analytic RF scaling function

    NASA Astrophysics Data System (ADS)

    Gai, Neville D.; Zur, Yuval

    2007-11-01

    At higher B0 fields, specific absorption rate (SAR) deposition increases. Due to maximum SAR limitation, slice coverage decreases and/or scan time increases. Conventional selective RF pulses are played out in conjunction with a time independent field gradient. Variable rate selective excitation (VERSE) is a technique that modifies the original RF and gradient waveforms such that slice profile is unchanged. The drawback is that the slice profile for off-resonance spins is distorted. A new VERSE algorithm based on modeling the scaled waveforms as a Fermi function is introduced. It ensures that system related constraints of maximum gradient amplitude and slew rate are not exceeded. The algorithm can be used to preserve the original RF pulse duration while minimizing SAR and peak b1 or to minimize the RF pulse duration. The design is general and can be applied to any symmetrical or asymmetrical RF waveform. The algorithm is demonstrated by using it to (a) minimize the SAR of a linear phase RF pulse, (b) minimize SAR of a hyperbolic secant RF pulse, and (c) minimize the duration of a linear phase RF pulse. Images with a T1-FLAIR (T1 FLuid Attenuated Inversion Recovery) sequence using a conventional and VERSE adiabatic inversion RF pulse are presented. Comparison of images and scan parameters for different anatomies and coils shows increased scan coverage and decreased SAR with the VERSE inversion RF pulse, while image quality is preserved.

  17. From the HINDAS Project: Excitation Functions for Residual Nuclide Production by Proton-Induced Reactions

    SciTech Connect

    Michel, R.; Gloris, M.; Protoschill, J.; Uosif, M.A.M.; Weug, M.; Herpers, U.; Kuhnhenn, J.; Kubik, P.-W.; Schumann, D.; Synal, H.-A.; Weinreich, R.; Leya, I.; David, J.C.; Leray, S.; Duijvestijn, M.; Koning, A.; Kelic, A.; Schmidt, K.H.; Cugnon, J.

    2005-05-24

    A survey is given about efforts undertaken during the HINDAS project to investigate the energy dependence of residual nuclide production by proton-induced reactions from thresholds up to 2.6 GeV. For proton-induced reactions, our experiments aimed to further develop and complete the cross-section database that was established by our collaboration in recent years. It was extended to the heavy-target elements Ta, W, Pb, and Bi for energies up to 2.6 GeV. In addition, new measurements for the target element iron were performed up to 2.6 GeV and for natural uranium for energies from 21 MeV to 69 MeV. For the target element lead, a comprehensive set of excitation functions published recently was completed by AMS-measurements of cross sections for the production of the long-lived radionuclides Be-10, Al-26, Cl-36, and I-129 and by mass spectrometric measurements for stable and radioactive rare gas isotopes of He, Ne, Ar, Kr, and Xe. Comprehensive tests of the nuclear-reaction codes TALYS and INCL4+ABLA, which were developed within the HINDAS project, were performed with the new experimental results over the entire energy range.

  18. Sub-barrier fusion excitation function data and energy dependent Woods-Saxon potential

    NASA Astrophysics Data System (ADS)

    Gautam, Manjeet Singh

    2016-07-01

    This paper analyzed the role of intrinsic degrees of freedom of colliding nuclei in the enhancement of sub-barrier fusion cross-section data of various heavy ion fusion reactions. The influences of inelastic surface vibrations of colliding pairs are found to be dominant and their couplings result in the significantly larger fusion enhancement over the predictions of the one dimensional barrier penetration model at sub-barrier energies. The theoretical calculations are performed by using energy dependent Woods-Saxon potential model (EDWSP model) in conjunction with the one dimensional Wong formula. The effects of dominant intrinsic channels are entertained within framework of the coupled channel calculations obtained by using the code CCFULL. It is quite interesting to note that the energy dependence in Woods-Saxon potential simulates the effects of inelastic surface vibrational states of reactants wherein significantly larger value of diffuseness parameter ranging from a = 0.85 fm to a = 0.95 fm is required to address the observed fusion excitation function data of the various heavy ion fusion reactions.

  19. The excitation functions of 187Re(n,2n) 186m,gRe reactions

    NASA Astrophysics Data System (ADS)

    Huang, Xiao-Long; Kang, Meng-Xiao; Liu, Li-Le; Wang, Ji-Min; Chen, Xiong-Jun

    2016-08-01

    A new value for the emission probability of 137.144 keV γ-rays from 186gRe decay is recommended to be (9.47±0.03)/%. Using this value the measured cross sections for 187Re(n,2n)186mRe and 187Re(n,2n)186gRe reactions around 14 MeV are analyzed, and the cross section for 187Re(n,2n)186m+gRe reaction at 14.8 MeV is (2213±116) mb. The UNF code was adopted to calculate the cross sections for the 187Re(n,2n)186m+gRe reaction below 20 MeV, fitting to the value (2213±116) mb at 14.8 MeV using a set of optimum neutron optical potential parameters which were obtained based on the relevant experimental data of rhenium. The isomeric cross section ratio for the 187Re(n,2n)186m,gRe reaction was analyzed using the V-H method based on nuclear statistical theory. Combining these calculated results, the excitation functions for the 187Re(n,2n)186mRe and 187Re(n,2n)186gRe reactions were obtained. The obtained results are in good agreement with the available experimental data.

  20. Charmed-strange meson spectrum: Old and new problems

    NASA Astrophysics Data System (ADS)

    Segovia, Jorge; Entem, David R.; Fernández, Francisco

    2015-05-01

    The LHCb Collaboration has recently reported the observation for the first time of a spin-3 resonance in the heavy quark sector. They have shown that the D¯0K- structure seen in the Bs0→D¯0K-π+ reaction and with invariant mass 2.86 GeV is an admixture of a spin-1 and a spin-3 resonance. Motivated by the good agreement between our theoretical predictions some time ago and the properties extracted from the experiment of the Ds1 *(2860 ) and Ds3 *(2860 ) states, we perform an extension of the study of the strong decay properties of the DsJ *(2860 ) and present the same analysis for the Ds1 *(2700 ) and Ds J(3040 ) mesons. This provides a unified and simultaneous description of the three higher excited charmed-strange resonances observed until now. For completeness, we present theoretical results for masses and strong decays of the low-lying charmed-strange mesons and those experimental missing states which belong to the spin multiplets of the discovered Ds1 *(2700 ), DsJ *(2860 ) and Ds J(3040 ) resonances. The theoretical framework used is a constituent quark model which successfully describes hadron phenomenology from light to heavy quark sectors.

  1. Coupled cluster and density functional studies on geometries and energies of excited C2v states of ozone

    NASA Astrophysics Data System (ADS)

    Grein, Friedrich

    2009-03-01

    The performance of single-determinant methods for finding geometries and energies of excited states is tested on the ozone molecule. Geometries for low-lying singlet and triplet states of ozone were optimized by CCSD(T) and density functional theory (DFT) (with BPW91 functional) methods. DFT geometries were found to lie close to CCSD(T) values. Most CCSD(T) and DFT geometries and energies are in good agreement with available experimental and recent high-level theoretical values, with deviations lying within 0.02 Å, 2°, and 0.3 eV. An exception is the 1 B12 state, having a larger deviation of bond distance and energy. A multiconfigurational treatment is required for this state. DFT geometry optimizations and calculations of vibrational frequencies were extended to higher states, covering over 30 excited states of ozone, with adiabatic excitation energies up to about 6 eV. Calculated harmonic frequencies showed several states, including 1 B12, to be saddle points. Multireference configuration interaction (MRCI) bending potentials for first and second singlet and triplet states were used in verifying the CCSD(T) and DFT geometries and for locating additional minima. For first states, DFT bending potentials are compared with MRCI potentials. As a criterion for the quality of single-determinant geometries and energies of excited states, comparison of their vertical excitation energies with MRCI or time-dependent DFT values is recommended.

  2. Analytical Hessian of electronic excited states in time-dependent density functional theory with Tamm-Dancoff approximation.

    PubMed

    Liu, Jie; Liang, WanZhen

    2011-07-01

    We present the analytical expression and computer implementation for the second-order energy derivatives of the electronic excited state with respect to the nuclear coordinates in the time-dependent density functional theory (TDDFT) with Gaussian atomic orbital basis sets. Here, the Tamm-Dancoff approximation to the full TDDFT is adopted, and therefore the formulation process of TDDFT excited-state Hessian is similar to that of configuration interaction singles (CIS) Hessian. However, due to the replacement of the Hartree-Fock exchange integrals in CIS with the exchange-correlation kernels in TDDFT, many quantitative changes in the derived equations are arisen. The replacement also causes additional technical difficulties associated with the calculation of a large number of multiple-order functional derivatives with respect to the density variables and the nuclear coordinates. Numerical tests on a set of test molecules are performed. The simulated excited-state vibrational frequencies by the analytical Hessian approach are compared with those computed by CIS and the finite-difference method. It is found that the analytical Hessian method is superior to the finite-difference method in terms of the computational accuracy and efficiency. The numerical differentiation can be difficult due to root flipping for excited states that are close in energy. TDDFT yields more exact excited-state vibrational frequencies than CIS, which usually overestimates the values. PMID:21744894

  3. Channels Active in the Excitability of Nerves and Skeletal Muscles across the Neuromuscular Junction: Basic Function and Pathophysiology

    ERIC Educational Resources Information Center

    Goodman, Barbara E.

    2008-01-01

    Ion channels are essential for the basic physiological function of excitable cells such as nerve, skeletal, cardiac, and smooth muscle cells. Mutations in genes that encode ion channels have been identified to cause various diseases and disorders known as channelopathies. An understanding of how individual ion channels are involved in the…

  4. A Preliminary Transcranial Magnetic Stimulation Study of Cortical Inhibition and Excitability in High-Functioning Autism and Asperger Disorder

    ERIC Educational Resources Information Center

    Enticott, Peter G.; Rinehart, Nicole J.; Tonge, Bruce J.; Bradshaw, John L.; Fitzgerald, Paul B.

    2010-01-01

    Aim: Controversy surrounds the distinction between high-functioning autism (HFA) and Asperger disorder, but motor abnormalities are associated features of both conditions. This study examined motor cortical inhibition and excitability in HFA and Asperger disorder using transcranial magnetic stimulation (TMS). Method: Participants were diagnosed by…

  5. Aromatic Lateral Substituents Influence the Excitation Energies of Hexaaza Lanthanide Macrocyclic Complexes: A Wave Function Theory and Density Functional Study.

    PubMed

    Rabanal-León, Walter A; Murillo-López, Juliana A; Páez-Hernández, Dayán; Arratia-Pérez, Ramiro

    2015-09-24

    The high interest in lanthanide chemistry, and particularly in their luminescence, has been encouraged by the need of understanding the lanthanide chemical coordination and how the design of new luminescent materials can be affected by this. This work is focused on the understanding of the electronic structure, bonding nature, and optical properties of a set of lanthanide hexaaza macrocyclic complexes, which can lead to potential optical applications. Here we found that the DFT ground state of the open-shell complexes are mainly characterized by the manifold of low lying f states, having small HOMO-LUMO energy gaps. The results obtained from the wave function theory calculations (SO-RASSI) put on evidence the multiconfigurational character of their ground state and it is observed that the large spin-orbit coupling and the weak crystal field produce a strong mix of the ground and the excited states. The electron localization function (ELF) and the energy decomposition analysis (EDA) support the idea of a dative interaction between the macrocyclic ligand and the lanthanide center for all the studied systems; noting that, this interaction has a covalent character, where the d-orbital participation is evidenced from NBO analysis, leaving the f shell completely noninteracting in the chemical bonding. From the optical part we observed in all cases the characteristic intraligand (IL) (π-π*) and ligand to metal charge-transfer (LMCT) bands that are present in the ultraviolet and visible regions, and for the open-shell complexes we found the inherent f-f electronic transitions on the visible and near-infrared region. PMID:26325624

  6. Validation of geophysical excitation functions by a rigorous combination with Earth orientation parameters and gravity field coefficients

    NASA Astrophysics Data System (ADS)

    Heiker, A.; Kutterer, H.

    2010-12-01

    Geophysical excitation functions model the re-distribution of atmospheric, oceanic and hydrologic masses. The change of the mass distribution of the Earth affects polar motion and length of day as well as gravity field coefficients of second degree. As all these quantities are related to the unknown Earth's tensor of inertia, a combined analysis allows to identify inconsistencies between the data and to determine the tensor of inertia. Usually, this physical relation between the Earth rotation parameters, excitation functions and second degree gravity field coefficients which is induced by the tensor of inertia, is not considered. In our study, we rigorously exploit it for the independent mutual validation based on least-squares estimation including variance-covariance component estimation. The functional model is based on the well known linear approximation of the Euler-Liouville equation. The construction of an appropriate stochastic model is hindered in practice due to insufficient knowledge on variances and covariances. Here, the missing stochastic information is determined empirically by analyzing the input data. Improved Earth orientation parameters, second degree gravity field coefficients and improved excitation functions are obtained as estimation results. Furthermore the unknown tensor of inertia is determined. The observation residuals indicate the degree of mutual consistency of the data. We give a short overview of our adjustment model. We present and discuss some results obtained from two different oceanic and atmospheric excitations (NCEP + ECCO and ECMWF + OMCT). The analysis and discussion of the resulting estimated excitation functions is emphasized. The work regarding the mutual validation is performed within the project P9 “Combined analysis and validation of Earth rotation models and observations” of the Research Unit FOR 584 (“Earth rotation and global dynamic processes”) which is funded by the German research funding organization DFG.

  7. Strange hadron production at low transverse momenta

    NASA Astrophysics Data System (ADS)

    Veres, Gábor I.; PHOBOS Collaboration; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Harrington, A. S.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Holynski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Lee, J. W.; Lin, W. T.; Manly, S.; Mignerey, A. C.; Noell, A.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Roland, C.; Roland, G.; Sagerer, J.; Sarin, P.; Sawicki, P.; Sedykh, I.; Skulski, W.; Smith, C. E.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Teng, R.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wyslouch, B.; Zhang, J.

    2004-01-01

    Some of the latest results of the PHOBOS experiment from the \\sqrt{s_{NN}}= 200\\ GeV Au+Au data are discussed. Those relevant to strangeness production are emphasized. These observations relate to the nature of the matter created when heavy ions collide at the highest achieved energy. The invariant yields of strange and non-strange charged hadrons at very low transverse momentum have been measured, and used to differentiate between different dynamical scenarios. In the intermediate transverse momentum range, the measured ratios of strange and anti-strange kaons approach one, while the antibaryon to baryon ratio is still significantly less, independent of collision centrality and transverse momentum. At high transverse momenta, we find that central and peripheral Au+Au collisions produce similar numbers of charged hadrons per participant nucleon pair, rather than per binary nucleon-nucleon collision. Finally, we describe the upgrades of PHOBOS completed for the 2003 d+Au and p+p run, which extend the transverse momentum range over which particle identification is possible and, at the same time, implement a trigger system selective for high-pT particles.

  8. Excitation function of the 60Ni(p ,γ )61Cu reaction from threshold to 16 MeV

    NASA Astrophysics Data System (ADS)

    Uddin, M. S.; Sudár, S.; Spahn, I.; Shariff, M. A.; Qaim, S. M.

    2016-04-01

    Excitation function of the reaction 60Ni(p ,γ )61Cu was measured via the activation technique in the energy range of 1.3-16.0 MeV using a low-energy accelerator and a small cyclotron. The results are comparable to those previously obtained via prompt γ counting. In addition excitation functions of the more common competing 60Ni(p ,n )60Cu and 60Ni(p ,α )57Co reactions were also measured. Theoretical calculations on proton-induced reactions on 60Ni were performed using the nuclear model code talys. The results suggest that near the threshold of the reaction the compound nucleus mechanism dominates. Thereafter the contribution of direct interactions becomes rather strong, especially between 4 and 6 MeV, i.e., just below the threshold of the 60Ni(p ,n )60Cu reaction. The cross section at the maximum of the excitation function of each of the three reactions, namely, 60Ni(p ,γ )61Cu,60Ni(p ,n )60Cu , and 60Ni(p ,α )57Co , amounts to 2, 320, and 85 mb, respectively. The (p ,n ) reaction is thus the most commonly occurring process, and the (p ,γ ) reaction is the weakest, possibly due to higher probability of particle emission than γ-ray emission from the highly excited intermediate nucleus 61Cu formed in the interaction of a proton with the target nucleus 60Ni.

  9. Excited states of ReO4-: A comprehensive time-dependent relativistic density functional theory study

    NASA Astrophysics Data System (ADS)

    Xu, Wenhua; Ma, Jianyi; Peng, Daoling; Zou, Wenli; Liu, Wenjian; Staemmler, Volker

    2009-02-01

    The perrhenate anion, ReO4-, is taken as a showcase of heavy transition metal complexes, to examine the performance of time-dependent relativistic density functional linear response theory for electronic excitations, which is based on a newly proposed exact two-component Hamiltonian resulting from the symmetrized elimination of the small component. In total 30 scalar and 63 spinor excited states are investigated and the results are grossly in good agreement with those by the singles and doubles coupled-cluster linear response theory. It is found that only a few scalar states of 3T1 and 3T2 symmetries are split significantly by the spin-orbit coupling, whereas only those excited states involving the Rydberg-type virtual orbital are affected by the solvent effects. The nature of the optical absorption spectra is also highlighted.

  10. Excited-State Absorption from Real-Time Time-Dependent Density Functional Theory: Optical Limiting in Zinc Phthalocyanine.

    PubMed

    Fischer, Sean A; Cramer, Christopher J; Govind, Niranjan

    2016-04-01

    Optical-limiting materials are capable of attenuating light to protect delicate equipment from high-intensity light sources. Phthalocyanines have attracted a lot of attention for optical-limiting applications due to their versatility and large nonlinear absorption. With excited-state absorption (ESA) being the primary mechanism for optical limiting behavior in phthalocyanines, the ability to tune the optical absorption of ground and excited states in phthalocyanines would allow for the development of advanced optical limiters. We recently developed a method for the calculation of ESA based on real-time time-dependent density functional theory propagation of an excited-state density. In this work, we apply the approach to zinc phthalocyanine, demonstrating the ability of our method to efficiently identify the optical limiting potential of a molecular complex. PMID:27007445

  11. Excitation functions for the helium-ion-induced fission of holmium and erbium

    SciTech Connect

    Iyer, R.H.; Pandey, A.K.; Kalsi, P.C.; Sharma, R.C. )

    1991-12-01

    Excitation functions for the helium-ion-induced fission of holmium ({ital Z}=67) and erbium ({ital Z}=68) in the energy range 34--70 MeV were measured using lexan polycarbonate plastic as the fission fragment track detector. By analyzing the data in terms of the statistical model expression for {Gamma}{sub {ital f}}/{Gamma}{sub {ital n}}, the ratio of the fission width to neutron emission width, the fission barriers of the compound nuclei {sup 1}{sub 69}{sup 69}Tm and {sup 17}{sub 70}{sup 1.3}Yb were determined to be 29.8{plus minus}3 and 27.8{plus minus}3 MeV, respectively. The corresponding values for the fission level density parameter were found to be {ital a}{sub {ital f}}={ital A}/12 and {ital A}/13, respectively. The uncertainties shown in the fission barriers allow for inclusion of other values derived from reasonable upper and lower limits of {ital a}{sub {ital f}} values of {ital A}/8 to {ital A}/20. The measured fission barriers compare very well with the shell-corrected liquid-drop barriers of Myers and Swiatecki. The present measurements extend the range of low-{ital Z} elements which are away from the closed-shell region and which are studied at these medium energies. The results are compared with similar data available in the literature which bring out some interesting correlations and trends in the fission properties, viz., fission barriers and level density parameters of low-{ital Z} elements.

  12. The Center for Functional Nanomaterials at Brookhaven National Lab

    SciTech Connect

    Dickerson, James

    2015-07-09

    Scientists from all over the world visit the Center for Functional Nanomaterials to explore strange phenomena hidden on the nanoscale—an exciting and powerful landscape spanning just billionths of a meter. The U.S. Department of Energy opened the CFN, one of its five nanoscale science research centers in the United States, to develop unprecedented energy technologies and solve fundamental scientific puzzles. Learn more about the CFN: https://www.bnl.gov/cfn/.

  13. Analytical approach for the excited-state Hessian in time-dependent density functional theory: Formalism, implementation, and performance

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Liang, WanZhen

    2011-11-01

    The paper presents the formalism, implementation, and performance of the analytical approach for the excited-state Hessian in the time-dependent density functional theory (TDDFT) that extends our previous work [J. Liu and W. Z. Liang, J. Chem. Phys. 135, 014113 (2011)] on the analytical Hessian in TDDFT within Tamm-Dancoff approximation (TDA) to full TDDFT. In contrast to TDA-TDDFT, an appreciable advantage of full TDDFT is that it maintains the oscillator strength sum rule, and therefore yields more precise results for the oscillator strength and other related physical quantities. For the excited-state harmonic vibrational frequency calculation, however, full TDDFT does not seem to be advantageous since the numerical tests demonstrate that the accuracy of TDDFT with and without TDA are comparable to each other. As a common practice, the computed harmonic vibrational frequencies are scaled by a suitable scale factor to yield good agreement with the experimental fundamental frequencies. Here we apply both the optimized ground-state and excited-state scale factors to scale the calculated excited-state harmonic frequencies and find that the scaling decreases the root-mean-square errors. The optimized scale factors derived from the excited-state calculations are slightly smaller than those from the ground-state calculations.

  14. Exciting: a full-potential all-electron package implementing density-functional theory and many-body perturbation theory.

    PubMed

    Gulans, Andris; Kontur, Stefan; Meisenbichler, Christian; Nabok, Dmitrii; Pavone, Pasquale; Rigamonti, Santiago; Sagmeister, Stephan; Werner, Ute; Draxl, Claudia

    2014-09-10

    Linearized augmented planewave methods are known as the most precise numerical schemes for solving the Kohn-Sham equations of density-functional theory (DFT). In this review, we describe how this method is realized in the all-electron full-potential computer package, exciting. We emphasize the variety of different related basis sets, subsumed as (linearized) augmented planewave plus local orbital methods, discussing their pros and cons and we show that extremely high accuracy (microhartrees) can be achieved if the basis is chosen carefully. As the name of the code suggests, exciting is not restricted to ground-state calculations, but has a major focus on excited-state properties. It includes time-dependent DFT in the linear-response regime with various static and dynamical exchange-correlation kernels. These are preferably used to compute optical and electron-loss spectra for metals, molecules and semiconductors with weak electron-hole interactions. exciting makes use of many-body perturbation theory for charged and neutral excitations. To obtain the quasi-particle band structure, the GW approach is implemented in the single-shot approximation, known as G(0)W(0). Optical absorption spectra for valence and core excitations are handled by the solution of the Bethe-Salpeter equation, which allows for the description of strongly bound excitons. Besides these aspects concerning methodology, we demonstrate the broad range of possible applications by prototypical examples, comprising elastic properties, phonons, thermal-expansion coefficients, dielectric tensors and loss functions, magneto-optical Kerr effect, core-level spectra and more. PMID:25135665

  15. Polarisation observables for strangeness photoproduction on a frozen spin target with CLAS at Jefferson Lab

    SciTech Connect

    Stuart Fegan

    2012-04-01

    The FROST experiment at Jefferson Lab used the CLAS detector in Hall B with the intention of performing a complete measurement of polarization observables associated with strangeness photoproduction, in combination with data from previous JLab experiments. This was achieved by utilizing the FROST polarized target in conjunction with polarized photon beams, allowing direct measurement of beam-target double polarization observables. By studying strangeness reactions, such as {gamma}p {yields} K{sup +}{Lambda}{sup 0}, it may be possible to find 'missing' baryon resonances, predicted by symmetric quark models but not observed in previous experiments, whose results are consistent with the di-quark model. It is thought these 'missing' resonances remain undiscovered because they have different coupling strengths for different reaction channels, such as the strangeness reactions, whereas the current data is dominated by studies of pN reactions. Observing these resonances therefore has important implications for our knowledge of the excited states of nucleons, and the models predicting the quark interactions within them. The G polarization observable is one of the beam-target double polarization observables, associated with a longitudinally polarized target and a linearly polarized photon beam, and its measurement for the strangeness reaction {gamma}p {yields} K{sup +}{Lambda}{sup 0} is the focus of the work presented.

  16. Theoretical study of excited states of DNA base dimers and tetramers using optimally tuned range-separated density functional theory.

    PubMed

    Sun, Haitao; Zhang, Shian; Zhong, Cheng; Sun, Zhenrong

    2016-03-15

    Excited states of various DNA base dimers and tetramers including Watson-Crick H-bonding and stacking interactions have been investigated by time-dependent density functional theory using nonempirically tuned range-separated exchange (RSE) functionals. Significant improvements are found in the prediction of excitation energies and oscillator strengths, with results comparable to those of high-level coupled-cluster (CC) models (RI-CC2 and EOM-CCSD(T)). The optimally-tuned RSE functional significantly outperforms its non-tuned (default) version and widely-used B3LYP functional. Compared to those high-level CC benchmarks, the large mean absolute deviations of conventional functionals can be attributed to their inappropriate amount of exact exchange and large delocalization errors which can be greatly eliminated by tuning approach. Furthermore, the impacts of H-bonding and π-stacking interactions in various DNA dimers and tetramers are analyzed through peak shift of simulated absorption spectra as well as corresponding change of absorption intensity. The result indicates the stacking interaction in DNA tetramers mainly contributes to the hypochromicity effect. The present work provides an efficient theoretical tool for accurate prediction of optical properties and excited states of nucleobase and other biological systems. © 2015 Wiley Periodicals, Inc. PMID:26666212

  17. Measurements of strangeness production in the STAR experiment at RHIC

    SciTech Connect

    Wilson, W.K.

    1995-07-15

    Simulations of the ability of the STAR (Solenoidal Tracker at RHIC) detector to measure strangeness production in central Au+Au collisions at RHIC are presented. Emphasis is placed on the reconstruction of short lived particles using a high resolution inner tracker. The prospects for performing neutral kaon interferometry are discussed. Simulation results for measurements of strange and multi-strange baryons are presented.

  18. Recent results from strangeness in transport models

    NASA Astrophysics Data System (ADS)

    Steinheimer, J.; Botvina, A. S.; Bleicher, M.

    2016-01-01

    In these proceedings we discuss recent developments in the microscopic description of strange particle production in nuclear collisions. We put a special emphasis on the production of hypernuclei at the upcoming FAIR and NICA facilities as well as the deep sub threshold, ϕ and Ξ- production yields measured with the HADES experiment. Employing new resonance decay channels we obtain a satisfactory description of ϕ and Ξ- production in deep sub threshold Ar+KCl reactions. Our results implicate that no new medium effects are required to describe the rare strange particle production data from low energy nuclear collisions.

  19. Some analytical models of anisotropic strange stars

    NASA Astrophysics Data System (ADS)

    Murad, Mohammad Hassan

    2016-01-01

    Over the years of the concept of local isotropy has become a too stringent condition in modeling relativistic self-gravitating objects. Taking local anisotropy into consideration, in this work, some analytical models of relativistic anisotropic charged strange stars have been developed. The Einstein-Maxwell gravitational field equations have been solved with a particular form of one of the metric potentials. The radial pressure and the energy density have been assumed to follow the usual linear equation of state of strange quark matter, the MIT bag model.

  20. Connecting coherent structures and strange attractors

    NASA Technical Reports Server (NTRS)

    Keefe, Laurence R.

    1990-01-01

    A concept of turbulence derived from nonlinear dynamical systems theory suggests that turbulent solutions to the Navier-Stokes equations are restricted to strange attractors, and, by implication, that turbulent phenomenology must find some expression or source in the structure of these mathematical objects. Examples and discussions are presented to link coherent structures to some of the commonly known characteristics of strange attractors. Basic to this link is a geometric interpretation of conditional sampling techniques employed to educe coherent structures that offers an explanation for their appearance in measurements as well as their size.

  1. Nonlinear electronic excitations in crystalline solids using meta-generalized gradient approximation and hybrid functional in time-dependent density functional theory.

    PubMed

    Sato, Shunsuke A; Taniguchi, Yasutaka; Shinohara, Yasushi; Yabana, Kazuhiro

    2015-12-14

    We develop methods to calculate electron dynamics in crystalline solids in real-time time-dependent density functional theory employing exchange-correlation potentials which reproduce band gap energies of dielectrics; a meta-generalized gradient approximation was proposed by Tran and Blaha [Phys. Rev. Lett. 102, 226401 (2009)] (TBm-BJ) and a hybrid functional was proposed by Heyd, Scuseria, and Ernzerhof [J. Chem. Phys. 118, 8207 (2003)] (HSE). In time evolution calculations employing the TB-mBJ potential, we have found it necessary to adopt the predictor-corrector step for a stable time evolution. We have developed a method to evaluate electronic excitation energy without referring to the energy functional which is unknown for the TB-mBJ potential. For the HSE functional, we have developed a method for the operation of the Fock-like term in Fourier space to facilitate efficient use of massive parallel computers equipped with graphic processing units. We compare electronic excitations in silicon and germanium induced by femtosecond laser pulses using the TB-mBJ, HSE, and a simple local density approximation (LDA). At low laser intensities, electronic excitations are found to be sensitive to the band gap energy: they are close to each other using TB-mBJ and HSE and are much smaller in LDA. At high laser intensities close to the damage threshold, electronic excitation energies do not differ much among the three cases. PMID:26671367

  2. Nonlinear electronic excitations in crystalline solids using meta-generalized gradient approximation and hybrid functional in time-dependent density functional theory

    NASA Astrophysics Data System (ADS)

    Sato, Shunsuke A.; Taniguchi, Yasutaka; Shinohara, Yasushi; Yabana, Kazuhiro

    2015-12-01

    We develop methods to calculate electron dynamics in crystalline solids in real-time time-dependent density functional theory employing exchange-correlation potentials which reproduce band gap energies of dielectrics; a meta-generalized gradient approximation was proposed by Tran and Blaha [Phys. Rev. Lett. 102, 226401 (2009)] (TBm-BJ) and a hybrid functional was proposed by Heyd, Scuseria, and Ernzerhof [J. Chem. Phys. 118, 8207 (2003)] (HSE). In time evolution calculations employing the TB-mBJ potential, we have found it necessary to adopt the predictor-corrector step for a stable time evolution. We have developed a method to evaluate electronic excitation energy without referring to the energy functional which is unknown for the TB-mBJ potential. For the HSE functional, we have developed a method for the operation of the Fock-like term in Fourier space to facilitate efficient use of massive parallel computers equipped with graphic processing units. We compare electronic excitations in silicon and germanium induced by femtosecond laser pulses using the TB-mBJ, HSE, and a simple local density approximation (LDA). At low laser intensities, electronic excitations are found to be sensitive to the band gap energy: they are close to each other using TB-mBJ and HSE and are much smaller in LDA. At high laser intensities close to the damage threshold, electronic excitation energies do not differ much among the three cases.

  3. Nonlinear electronic excitations in crystalline solids using meta-generalized gradient approximation and hybrid functional in time-dependent density functional theory

    SciTech Connect

    Sato, Shunsuke A.; Taniguchi, Yasutaka; Shinohara, Yasushi; Yabana, Kazuhiro

    2015-12-14

    We develop methods to calculate electron dynamics in crystalline solids in real-time time-dependent density functional theory employing exchange-correlation potentials which reproduce band gap energies of dielectrics; a meta-generalized gradient approximation was proposed by Tran and Blaha [Phys. Rev. Lett. 102, 226401 (2009)] (TBm-BJ) and a hybrid functional was proposed by Heyd, Scuseria, and Ernzerhof [J. Chem. Phys. 118, 8207 (2003)] (HSE). In time evolution calculations employing the TB-mBJ potential, we have found it necessary to adopt the predictor-corrector step for a stable time evolution. We have developed a method to evaluate electronic excitation energy without referring to the energy functional which is unknown for the TB-mBJ potential. For the HSE functional, we have developed a method for the operation of the Fock-like term in Fourier space to facilitate efficient use of massive parallel computers equipped with graphic processing units. We compare electronic excitations in silicon and germanium induced by femtosecond laser pulses using the TB-mBJ, HSE, and a simple local density approximation (LDA). At low laser intensities, electronic excitations are found to be sensitive to the band gap energy: they are close to each other using TB-mBJ and HSE and are much smaller in LDA. At high laser intensities close to the damage threshold, electronic excitation energies do not differ much among the three cases.

  4. A simplified Tamm-Dancoff density functional approach for the electronic excitation spectra of very large molecules

    NASA Astrophysics Data System (ADS)

    Grimme, Stefan

    2013-06-01

    Two approximations in the Tamm-Dancoff density functional theory approach (TDA-DFT) to electronically excited states are proposed which allow routine computations for electronic ultraviolet (UV)- or circular dichroism (CD) spectra of molecules with 500-1000 atoms. Speed-ups compared to conventional time-dependent DFT (TD-DFT) treatments of about two to three orders of magnitude in the excited state part at only minor loss of accuracy are obtained. The method termed sTDA ("s" for simplified) employs atom-centered Löwdin-monopole based two-electron repulsion integrals with the asymptotically correct 1/R behavior and perturbative single excitation configuration selection. It is formulated generally for any standard global hybrid density functional with given Fock-exchange mixing parameter ax. The method performs well for two standard benchmark sets of vertical singlet-singlet excitations for values of ax in the range 0.2-0.6. The mean absolute deviations from reference data are only 0.2-0.3 eV and similar to those from standard TD-DFT. In three cases (two dyes and one polypeptide), good mutual agreement between the electronic spectra (up to 10-11 eV excitation energy) from the sTDA method and those from TD(A)-DFT is obtained. The computed UV- and CD-spectra of a few typical systems (e.g., C60, two transition metal complexes, [7]helicene, polyalanine, a supramolecular aggregate with 483 atoms and about 7000 basis functions) compare well with corresponding experimental data. The method is proposed together with medium-sized double- or triple-zeta type atomic-orbital basis sets as a quantum chemical tool to investigate the spectra of huge molecular systems at a reliable DFT level.

  5. Linear interpolation method in ensemble Kohn-Sham and range-separated density-functional approximations for excited states

    NASA Astrophysics Data System (ADS)

    Senjean, Bruno; Knecht, Stefan; Jensen, Hans Jørgen Aa.; Fromager, Emmanuel

    2015-07-01

    Gross-Oliveira-Kohn density-functional theory (GOK-DFT) for ensembles is, in principle, very attractive but has been hard to use in practice. A practical model based on GOK-DFT for the calculation of electronic excitation energies is discussed. The model relies on two modifications of GOK-DFT: use of range separation and use of the slope of the linearly interpolated ensemble energy, rather than orbital energies. The range-separated approach is appealing, as it enables the rigorous formulation of a multideterminant state-averaged DFT method. In the exact theory, the short-range density functional, which complements the long-range wave-function-based ensemble energy contribution, should vary with the ensemble weights even when the density is held fixed. This weight dependence ensures that the range-separated ensemble energy varies linearly with the ensemble weights. When the (weight-independent) ground-state short-range exchange-correlation functional is used in this context, curvature appears, thus leading to an approximate weight-dependent excitation energy. In order to obtain unambiguous approximate excitation energies, we propose to interpolate linearly the ensemble energy between equiensembles. It is shown that such a linear interpolation method (LIM) can be rationalized and that it effectively introduces weight dependence effects. As proof of principle, the LIM has been applied to He, Be, and H2 in both equilibrium and stretched geometries as well as the stretched HeH+ molecule. Very promising results have been obtained for both single (including charge transfer) and double excitations with spin-independent short-range local and semilocal functionals. Even at the Kohn-Sham ensemble DFT level, which is recovered when the range-separation parameter is set to 0, LIM performs better than standard time-dependent DFT.

  6. Excitation functions of (nat)Zn(p,x) nuclear reactions with proton beam energy below 18 MeV.

    PubMed

    Asad, Ali H; Chan, Sun; Morandeau, Laurence; Cryer, David; Smith, Suzanne V; Price, Roger I

    2014-12-01

    We measured the excitation functions of (nat)Zn (p,x) reactions up to 17.6MeV, using the stacked-foils activation technique. High-purity natural zinc (and copper) foils were irradiated with proton beams generated by an 18MeV isochronous cyclotron. Activated foils were measured using high-purity Ge gamma spectroscopy to quantify the radionuclides (61)Cu, (66)Ga, (67)Ga, and (65)Zn produced from the reactions. Thick-target integral yields were also deduced from the measured excitation functions of the produced radioisotopes. These results were compared with the published literature and were found to be in good agreement with most reports, particularly those most recently compiled. PMID:25108597

  7. Excitation functions for (d,x) reactions on (133)Cs up to Ed=40MeV.

    PubMed

    Tárkányi, F; Ditrói, F; Takács, S; Hermanne, A; Baba, M; Ignatyuk, A V

    2016-04-01

    In the frame of a systematic study of excitation functions of deuteron induced reactions the excitation functions of the (133)Cs(d,x)(133m,133mg,131mg)Ba,(134,)(132)Cs and (12)(9m)Xe nuclear reactions were measured up to 40MeV deuteron energies by using the stacked foil irradiation technique and γ-ray spectroscopy of activated samples. The results were compared with calculations performed with the theoretical nuclear reaction codes ALICE-IPPE-D, EMPIRE II-D and TALYS calculation listed in the TENDL-2014 library. A moderate agreement was obtained. Based on the integral yields deduced from our measured cross sections, production of (131)Cs via the (133)Cs(d,4n)(131)Ba→(131)Cs reaction and (133)Ba via (133)Cs(d,2n) reactions is discussed in comparison with other charged particle production routes. PMID:26773822

  8. Measurement of the {sup 208}Pb({sup 52}Cr,n){sup 259}Sg excitation function

    SciTech Connect

    Folden III, C. M.; Dragojevic, I.; Garcia, M. A.; Gates, J. M.; Nelson, S. L.; Hoffman, D. C.; Nitsche, H.; Duellmann, Ch. E.; Sudowe, R.; Gregorich, K. E.; Eichler, R.

    2009-02-15

    The excitation function for the {sup 208}Pb({sup 52}Cr,n){sup 259}Sg reaction has been measured using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. The maximum cross section of 320{sub -100}{sup +110} pb is observed at a center-of-target laboratory-frame energy of 253.0 MeV. In total, 25 decay chains originating from {sup 259}Sg were observed and the measured decay properties are in good agreement with previous reports. In addition, a partial excitation function for the {sup 208}Pb({sup 52}Cr,2n){sup 258}Sg reaction was obtained, and an improved {sup 258}Sg half-life of 2.6{sub -0.4}{sup +0.6} ms was calculated by combining all available experimental data.

  9. Theory of ground- and excited state-properties of solids, surfaces, and interfaces: Beyond density functional formalsim

    SciTech Connect

    Louie, S.G.

    1988-10-01

    Two recently developed approaches for calculating properties of materials going beyond the density functional formalism are discussed. For excited-state properties, a first-principles quasiparticle theory has been developed. The electron self-energy operator is calculated using the full dielectric matrix and the dressed Green's function. Electron excitation spectra are interpreted as transitions between quasiparticle states of an interacting many-electron system. For ground-state properties, a new method using nonlocal pseudopotentials in conjunction with the variational quantum Monte Carlo approach is introduced. Electron correlations are treated using the exact interaction with a correlated wavefunction of the Jastrow-Slater form. Selected examples from bulk, surface, and interface calculations are presented to illustrate the capabilities of these two approaches. 47 refs., 6 figs., 5 tabs.

  10. Strange Bedfellows; Physical and Biological Oceanographers

    NASA Astrophysics Data System (ADS)

    Wooster, W. S.

    2002-12-01

    When I started graduate study at Scripps in 1947, both the text, "The Oceans", and the curriculum - all students took the introductory courses in physics, chemistry, biology, and geology - conspired to create awareness of the interactions among these fields. In their preface, the authors spoke of the book as "an aid to the beginner and specialist alike in the coordination of the various fields of oceanography." Harald Sverdrup, perhaps the best known physical oceanographer of his day, introduced us to the interdisciplinary organization, ICES, wrote an important paper (1953) on "the vernal blooming of phytoplankton", and together with fishery biologist O.E.Sette, launched the world renowned CalCOFI program. Another noted physical oceanographer, Henry Stommel, 1949, teamed up with biologist Gordon Riley in a major study of the quantitative ecology of plankton. At the time, physical and biological oceanographers often seemed to be engaged in the same mission. The curriculum format, with its four basic courses, spread to most other graduate programs in oceanography, but the forces of specialization also spread. While the biological oceanographers have always seen the need to understand the milieu within which their creatures function, the physicists often seemed to chafe against wasting their time on squishy subjects like biology when there were so many more important and fascinating things to study. Interactions were further complicated by the confusion between "biological oceanography" and "marine biology", and by the status of "fishery biology" which was often disdained by oceanographers of all stripes. I propose to discuss the evolution of the relationship among these fields during the 60 years since "The Oceans" was first published, concluding with the present marriage of convenience, or at least amicable co-habitation, forced by the widespread concern over the threat of global warming and the need to understand its consequences. It has become clear that

  11. Excitation functions for {sup 208-211}Fr produced in the {sup 18}O+{sup 197}Au fusion reaction

    SciTech Connect

    Corradi, L.; Behera, B.R.; Fioretto, E.; Gadea, A.; Latina, A.; Stefanini, A.M.; Szilner, S.; Trotta, M.; Wu, Y.; Beghini, S.; Montagnoli, G.; Scarlassara, F.; Sagaidak, R.N.; Atutov, S.N.; Mai, B.; Stancari, G.; Tomassetti, L.; Mariotti, E.; Khanbekyan, A.; Veronesi, S.

    2005-01-01

    Excitation functions for {sup 208-211}Fr isotopes produced in the {sup 18}O+{sup 197}Au fusion-evaporation reaction have been measured at E{sub lab}=75-130 MeV via characteristic {alpha} decays by means of an electrostatic deflector and a semiconductor detector. Data have been compared with calculations giving barrier-passing (capture) cross sections and probabilities of the compound nucleus decay into different channels according to the standard statistical model.

  12. Last orbits of binary strange quark stars

    SciTech Connect

    Limousin, Francois; Gourgoulhon, Eric; Gondek-Rosinska, Dorota

    2005-03-15

    We present the first relativistic calculations of the final phase of inspiral of a binary system consisting of two stars built predominantly of strange quark matter (strange quark stars). We study the precoalescing stage within the Isenberg-Wilson-Mathews approximation of general relativity using a multidomain spectral method. A hydrodynamical treatment is performed under the assumption that the flow is either rigidly rotating or irrotational, taking into account the finite density at the stellar surface--a distinctive feature with respect to the neutron star case. The gravitational-radiation driven evolution of the binary system is approximated by a sequence of quasiequilibrium configurations at fixed baryon number and decreasing separation. We find that the innermost stable circular orbit (ISCO) is given by an orbital instability both for synchronized and irrotational systems. This contrasts with neutron stars for which the ISCO is given by the mass-shedding limit in the irrotational case. The gravitational wave frequency at the ISCO, which marks the end of the inspiral phase, is found to be {approx}1400 Hz for two irrotational 1.35 M{sub {center_dot}} strange stars and for the MIT bag model of strange matter with massless quarks and a bag constant B=60 MeV fm{sup -3}. Detailed comparisons with binary neutrons star models, as well as with third order post-Newtonian point-mass binaries are given.

  13. 'Strange money': risk, finance and socialized debt.

    PubMed

    Dodd, Nigel

    2011-03-01

    This paper explores an essential but neglected aspect of recent discussions of the banking and financial system, namely money itself. Specifically, I take up a distinction drawn by Susan Strange which has never been fully elaborated: between a financial system that is global, and an international monetary system that remains largely territorial. I propose a sociological elaboration of this distinction by examining each category, 'finance' and 'money', in terms of its distinctive orientation to risk and debt. Money is distinguished by its high degree of liquidity and low degree of risk, corresponding to expectations that derive from its status as a 'claim upon society'- a form of socialized debt. But as Strange argued, these features of money are being undermined by the proliferation of sophisticated instruments of financial risk management -'strange money'- that, as monetary substitutes, both weaken states' capacity to manage money, and more broadly, contribute to 'overbanking'. The ultimate danger, according to Strange, is the 'death of money'. The paper concludes by exploring the implications of the distinction for sociological arguments about the changing nature of money. PMID:21361907

  14. Seismic Search for Strange Quark Matter

    NASA Technical Reports Server (NTRS)

    Teplitz, Vigdor

    2004-01-01

    Two decades ago, Witten suggested that the ground state of matter might be material of nuclear density made from up, down and strange quarks. Since then, much effort has gone into exploring astrophysical and other implications of this possibility. For example, neutron stars would almost certainly be strange quark stars; dark matter might be strange quark matter. Searches for stable strange quark matter have been made in various mass ranges, with negative, but not conclusive results. Recently, we [D. Anderson, E. Herrin, V. Teplitz, and I. Tibuleac, Bull. Seis. Soc. of Am. 93, 2363 (2003)] reported a positive result for passage through the Earth of a multi-ton "nugget" of nuclear density in a search of about a million seismic reports, to the U.S. Geological Survey for the years 1990-93, not associated with known Earthquakes. I will present the evidence (timing of first signals to the 9 stations involved, first signal directions, and unique waveform characteristics) for our conclusion and discuss potential improvements that could be obtained from exploiting the seismologically quieter environments of the moon and Mars.

  15. Variation of excited-state dynamics in trifluoromethyl functionalized C60 fullerenes.

    PubMed

    Park, Jaehong; Ramirez, Jessica J; Clikeman, Tyler T; Larson, Bryon W; Boltalina, Olga V; Strauss, Steven H; Rumbles, Garry

    2016-08-17

    We report on electronically excited-state dynamics of three different trifluoromethyl C60 fullerenes (TMFs, C60(CF3)n: C60/4-1, C60/6-2, and C60/10-1, featuring four, six, and ten trifluoromethyl groups, respectively) using steady-state and time-resolved optical spectroscopy as well as ultrafast pump/probe transient absorption spectroscopy. C60/4-1 and C60/6-2 dissolved in toluene solvent show near-unity S1 → T1 intersystem crossing quantum yield (ΦISC), ca. 1 ns S1-state lifetimes, and microsecond-timescale T1-state lifetimes, which are typical of the fullerene class. On the other hand, C60/10-1 exhibits a dominant sub-nanosecond nonradiative S1 → S0 relaxation mechanism and negligible ΦISC, therefore decreasing the average excited-state lifetime (τavg) by about 5 orders of magnitude compared to that of C60/4-1 and C60/6-2 (τavg ≈ 17 μs and 54 μs for C60/4-1 and C60/6-2, respectively, whereas τavg ≈ 100 ps for C60/10-1). These excited-state characteristics of C60/4-1 and C60/6-2 are preserved in polymer matrix, suggesting that fullerene/polymer interactions do not modulate intrinsic photophysics of trifluoromethyl-substituted fullerenes. The contrasting excited-state study results of C60/4-1 and C60/6-2 to that of C60/10-1 infer that intrinsic optical properties and excited-state dynamics can be affected by the substitution on the fullerene. PMID:27485768

  16. Influence of neglected covariances on the estimation of Earth rotation parameters, geophysical excitation functions and second degree gravity field coefficients

    NASA Astrophysics Data System (ADS)

    Heiker, Andrea; Kutterer, Hansjörg

    2010-05-01

    The Earth rotation variability is redundantly described by the combination of Earth rotation parameters (polar motion and length of day), geophysical excitation functions and second degree gravity field coefficients. There exist some publications regarding the comparison of the Earth rotation parameters and excitation functions. However, most authors do not make use of the redundancy. In addition, existing covariances between the input parameters are not considered. As shown in previous publications we use the redundancy for the independent mutual validation of the Earth rotation parameters, excitation functions and second degree gravity field coefficients based on an extended Gauss-Markov model and least-squares adjustment. The work regarding the mutual validation is performed within the project P9 "Combined analysis and validation of Earth rotation models and observations" of the research Unit FOR 584 ("Earth rotation and global dynamic processes") which is funded by the German Research Unit (DFG); see also abstract "Combined Analysis and Validation of Earth Rotation Models and Observations". The adjustment model is determined at first by the joint functional relations between the parameters and second by the stochastic model of the input data. A variance-covariance component estimation is included in the adjustment model. The functional model is based on the linearized Euler-Liouville equation. The construction of an appropriate stochastic model is prevented in practice by insufficient knowledge on variances and covariances. However, some numerical results derived from arbitrarily chosen stochastic models indicate that the stochastic model may be crucial for a correct estimation. The missing information is approximated by analyzing the input data. Synthetic variance-covariance matrices are constructed by considering empirical auto- and cross-correlation functions. The influence of neglected covariances is quantified and discussed by comparing the results derived

  17. Double excitations and state-to-state transition dipoles in π-π∗ excited singlet states of linear polyenes: Time-dependent density-functional theory versus multiconfigurational methods

    NASA Astrophysics Data System (ADS)

    Mikhailov, Ivan A.; Tafur, Sergio; Masunov, Artëm E.

    2008-01-01

    The effect of static and dynamic electron correlation on the nature of excited states and state-to-state transition dipole moments is studied with a multideterminant wave function approach on the example of all-trans linear polyenes ( C4H6 , C6H8 , and C8H10 ). Symmetry-forbidden singlet nAg states were found to separate into three groups: purely single, mostly single, and mostly double excitations. The excited-state absorption spectrum is dominated by two bright transitions: 1Bu-2Ag and 1Bu-mAg , where mAg is the state, corresponding to two-electron excitation from the highest occupied to lowest unoccupied molecular orbital. The richness of the excited-state absorption spectra and strong mixing of the doubly excited determinants into lower- nAg states, reported previously at the complete active space self-consistent field level of theory, were found to be an artifact of the smaller active space, limited to π orbitals. When dynamic σ-π correlation is taken into account, single- and double-excited states become relatively well separated at least at the equilibrium geometry of the ground state. This electronic structure is closely reproduced within time-dependent density-functional theory (TD DFT), where double excitations appear in a second-order coupled electronic oscillator formalism and do not mix with the single excitations obtained within the linear response. An extension of TD DFT is proposed, where the Tamm-Dancoff approximation (TDA) is invoked after the linear response equations are solved (a posteriori TDA). The numerical performance of this extension is validated against multideterminant-wave-function and quadratic-response TD DFT results. It is recommended for use with a sum-over-states approach to predict the nonlinear optical properties of conjugated molecules.

  18. Excitation function Analysis for Charmonium Production in Heavy-Ion Collisions

    NASA Astrophysics Data System (ADS)

    Zhou, Kai

    2016-01-01

    Both color screening and regeneration are hot medium effects on charmonium production in heavy ion collisions. While they affect in an opposite way the charmonium yield, their competition in transverse dynamics bring sensitivity to the ratio of averaged transverse momentum square for charmonium, which thus can reveal more nature of the QCD medium created from the collisions. We make an excitation analysis based on transport approach to illustrate such a picuture.

  19. Fluctuations, strangeness, and quasiquarks in heavy-ion collisions from lattice QCD

    NASA Astrophysics Data System (ADS)

    Gavai, R. V.; Gupta, Sourendu

    2006-01-01

    We report measurements of diagonal susceptibilities for the baryon number, χB, electrical charge, χQ, third component of isospin, χI, strangeness, χS, and hypercharge, χY, as well as the off-diagonal χBQ, χBY, χBS, etc. We show that the ratios of susceptibilities in the high-temperature phase are robust variables, independent of lattice spacing, and therefore give predictions for experiments. We also investigate strangeness production and flavor symmetry breaking matrix elements at finite temperature. Finally, we present evidence that in the high-temperature phase of QCD the different flavor quantum numbers are excited in linkages which are exactly the same as one expects from quarks. We present some investigations of these quarklike quasiparticles.

  20. Evaporation residue excitation function measurements in 50Ti- and 54Cr-induced reactions with lanthanide targets

    NASA Astrophysics Data System (ADS)

    Mayorov, D. A.; Werke, T. A.; Alfonso, M. C.; Tereshatov, E. E.; Bennett, M. E.; Frey, M. M.; Folden, C. M.

    2015-11-01

    Cross sections for the production of shell-stabilized evaporation residues in the 50Ti+Gd160 , 159Tb, 162Dy , and 54Cr+Dy162 reactions are reported. The compound nucleus excitation energy range considered principally covers the 4 n evaporation channel with segments of the 3 n and 5 n channels also measured. The resultant production cross sections are for nuclides with Z =86 -90 . From an analysis based on a statistical model, it is concluded that a larger fission probability than that predicted by the Bohr-Wheeler transition-state theory is needed to describe the data. This outcome is attributed to the influence of collective nuclear excitations. Subsequently, the expected stability enhancement against fission due to the influence of the magic N =126 shell is not evident. The x n excitation functions measured in previous experiments in the reactions 48Ca+Gd154 , 159Tb,Dy162 , and 165Ho are combined with the present data for Z >20 projectiles to illustrate systematic behavior of measured cross sections as a function of the difference in fission barrier and neutron separation energy.

  1. Photosensitized Singlet Oxygen Production upon Two-Photon Excitation of Single-Walled Carbon Nanotubes and Their Functionalized Analogs

    PubMed Central

    Gandra, Naveen; Chiu, Pui Lam; Li, Wenbing; Anderson, Yolanda R.; Mitra, Somenath; He, Huixin; Gao, Ruomei

    2009-01-01

    Single-walled carbon nanotubes (SWNTs) functionalized with -COOH (along with some sulphonation and nitration), and/or modified with chitosan were prepared and tested for their singlet oxygen (1O2) production. The emission from 1O2 observed upon SWNT irradiation at 532 nm was due to a two-photon process, while 1O2 production via excitation at 355 nm occurred through a conventional one-photon pathway. The relative quantum yield of 1O2 production at excitation wavelength of 532 nm was found to be 0.00, 0.07-0.13 and 0.24-0.54 for highly-functionalized, partially-functionalized and non-functionalized SWNT samples respectively. The nanotube-mediated generation of 1O2 may find applications in both targeted destruction of tumor cells and selective degradation of drug molecules. Our research provides a practical approach to modulate the production of reactive oxygen species from SWNTs via surface functionalization/modification. PMID:20046942

  2. Role of physiological ClC-1 Cl- ion channel regulation for the excitability and function of working skeletal muscle.

    PubMed

    Pedersen, Thomas Holm; Riisager, Anders; de Paoli, Frank Vincenzo; Chen, Tsung-Yu; Nielsen, Ole Bækgaard

    2016-04-01

    Electrical membrane properties of skeletal muscle fibers have been thoroughly studied over the last five to six decades. This has shown that muscle fibers from a wide range of species, including fish, amphibians, reptiles, birds, and mammals, are all characterized by high resting membrane permeability for Cl(-) ions. Thus, in resting human muscle, ClC-1 Cl(-) ion channels account for ∼80% of the membrane conductance, and because active Cl(-) transport is limited in muscle fibers, the equilibrium potential for Cl(-) lies close to the resting membrane potential. These conditions-high membrane conductance and passive distribution-enable ClC-1 to conduct membrane current that inhibits muscle excitability. This depressing effect of ClC-1 current on muscle excitability has mostly been associated with skeletal muscle hyperexcitability in myotonia congenita, which arises from loss-of-function mutations in the CLCN1 gene. However, given that ClC-1 must be drastically inhibited (∼80%) before myotonia develops, more recent studies have explored whether acute and more subtle ClC-1 regulation contributes to controlling the excitability of working muscle. Methods were developed to measure ClC-1 function with subsecond temporal resolution in action potential firing muscle fibers. These and other techniques have revealed that ClC-1 function is controlled by multiple cellular signals during muscle activity. Thus, onset of muscle activity triggers ClC-1 inhibition via protein kinase C, intracellular acidosis, and lactate ions. This inhibition is important for preserving excitability of working muscle in the face of activity-induced elevation of extracellular K(+) and accumulating inactivation of voltage-gated sodium channels. Furthermore, during prolonged activity, a marked ClC-1 activation can develop that compromises muscle excitability. Data from ClC-1 expression systems suggest that this ClC-1 activation may arise from loss of regulation by adenosine nucleotides and

  3. Searches for a possible strangeness S = -2 dibaryon

    SciTech Connect

    Barnes, P. D.

    1982-01-01

    Since the advent of QCD there has been a strong interest in manifestations of quark degrees of freedom in medium energy nuclear and particle physics. Within the framework of multiquark states the emphasis has centered on states with more than three quarks bound by colour forces rather than by the conventional mesonic forces. Dibaryon systems have played an important role within that framework. One of the most spectacular and exciting predictions is the possible existence, according to the MIT bag model, of a stable, flavor-singlet, strangeness = /sup -/2,J/sup P/ = 0/sup +/ dihyperon, called by R. Jaffe the H particle. It is a six-quark object (2u, 2d, 2s quarks) with a predicted mass around 2150 MeV, i.e., below the ..lambda lambda.. mass with a binding energy around 80 MeV. Its decay channels would be restricted to ..sigma..N and ..lambda..N, via the weak interaction. The relevant two body states are shown. A similar prediction was obtained on the basis of the same model by Mulders et al., with a mass of 2164 MeV for this state. For completeness it should be mentioned that in a recent estimate of the center-of-mass correction to the static MIT bag model, the authors suggest that the dilambda mass moves up to just above the ..lambda lambda.. threshold. These calculations are undergoing further tets. Although all these results come from a specific model, Lipkin has argued that the general features of QCD and the known baryon mass splittings imply that the six-quark state with charge zero, spin zero, and strangeness = /sup -/2 would have the greatest binding potential.

  4. Two-photon excited fluorescence of intrinsic fluorophores enables label-free assessment of adipose tissue function

    PubMed Central

    Alonzo, Carlo Amadeo; Karaliota, Sevasti; Pouli, Dimitra; Liu, Zhiyi; Karalis, Katia P.; Georgakoudi, Irene

    2016-01-01

    Current methods for evaluating adipose tissue function are destructive or have low spatial resolution. These limit our ability to assess dynamic changes and heterogeneous responses that occur in healthy or diseased subjects, or during treatment. Here, we demonstrate that intrinsic two-photon excited fluorescence enables functional imaging of adipocyte metabolism with subcellular resolution. Steady-state and time-resolved fluorescence from intracellular metabolic co-factors and lipid droplets can distinguish the functional states of excised white, brown, and cold-induced beige fat. Similar optical changes are identified when white and brown fat are assessed in vivo. Therefore, these studies establish the potential of non-invasive, high resolution, endogenous contrast, two-photon imaging to identify distinct adipose tissue types, monitor their functional state, and characterize heterogeneity of induced responses. PMID:27491409

  5. Two-photon excited fluorescence of intrinsic fluorophores enables label-free assessment of adipose tissue function

    NASA Astrophysics Data System (ADS)

    Alonzo, Carlo Amadeo; Karaliota, Sevasti; Pouli, Dimitra; Liu, Zhiyi; Karalis, Katia P.; Georgakoudi, Irene

    2016-08-01

    Current methods for evaluating adipose tissue function are destructive or have low spatial resolution. These limit our ability to assess dynamic changes and heterogeneous responses that occur in healthy or diseased subjects, or during treatment. Here, we demonstrate that intrinsic two-photon excited fluorescence enables functional imaging of adipocyte metabolism with subcellular resolution. Steady-state and time-resolved fluorescence from intracellular metabolic co-factors and lipid droplets can distinguish the functional states of excised white, brown, and cold-induced beige fat. Similar optical changes are identified when white and brown fat are assessed in vivo. Therefore, these studies establish the potential of non-invasive, high resolution, endogenous contrast, two-photon imaging to identify distinct adipose tissue types, monitor their functional state, and characterize heterogeneity of induced responses.

  6. Two-photon excited fluorescence of intrinsic fluorophores enables label-free assessment of adipose tissue function.

    PubMed

    Alonzo, Carlo Amadeo; Karaliota, Sevasti; Pouli, Dimitra; Liu, Zhiyi; Karalis, Katia P; Georgakoudi, Irene

    2016-01-01

    Current methods for evaluating adipose tissue function are destructive or have low spatial resolution. These limit our ability to assess dynamic changes and heterogeneous responses that occur in healthy or diseased subjects, or during treatment. Here, we demonstrate that intrinsic two-photon excited fluorescence enables functional imaging of adipocyte metabolism with subcellular resolution. Steady-state and time-resolved fluorescence from intracellular metabolic co-factors and lipid droplets can distinguish the functional states of excised white, brown, and cold-induced beige fat. Similar optical changes are identified when white and brown fat are assessed in vivo. Therefore, these studies establish the potential of non-invasive, high resolution, endogenous contrast, two-photon imaging to identify distinct adipose tissue types, monitor their functional state, and characterize heterogeneity of induced responses. PMID:27491409

  7. The relevance of non-excitable cells for cardiac pacemaker function

    PubMed Central

    Fahrenbach, John P; Mejia-Alvarez, Rafael; Banach, Kathrin

    2007-01-01

    Age-dependent changes in the architecture of the sinus node comprise an increasing ratio between fibroblasts and cardiomyocytes. This change is discussed as a potential mechanism for sinus node disease. The goal of this study was to determine the mechanism through which non-excitable cells influence the spontaneous activity of multicellular cardiomyocyte preparations. Cardiomyocyte monolayers (HL-1 cells) or embryonic stem cell-derived cardiomyocytes were used as two- and three-dimensional cardiac pacemaker models. Spontaneous activity and conduction velocity (θ) were monitored by field potential measurements with microelectrode arrays (MEAs). The influence of fibroblasts (WT-fibs) was determined in heterocellular cultures of different cardiomyocyte and fibroblast ratios. The relevance of heterocellular gap junctional coupling was evaluated by the use of fibroblasts deficient for the expression of Cx43 (Cx43−/−-fibs). The beating frequency and θ of heterocellular cultures depended negatively on the fibroblast concentration. Interspersion of fibroblasts in cardiomyocyte monolayers increased the coefficient of the interbeat interval variability. Whereas Cx43−/−-fibs decreased θ significantly less than WT-fibs, their effect on the beating frequency and the beat-to-beat variability seemed largely independent of their ability to establish intercellular coupling. These results suggest that electrically integrated, non-excitable cells modulate the excitability of cardiac pacemaker preparations by two distinct mechanisms, one dependent and the other independent of the heterocellular coupling established. Whereas heterocellular coupling enables the fibroblast to depolarize the cardiomyocytes or to act as a current sink, the mere physical separation of the cardiomyocytes by fibroblasts induces bradycardia through a reduction in frequency entrainment. PMID:17932143

  8. Time Course of Corticospinal Excitability and Autonomic Function Interplay during and Following Monopolar tDCS

    PubMed Central

    Santarnecchi, Emiliano; Feurra, Matteo; Barneschi, Federico; Acampa, Maurizio; Bianco, Giovanni; Cioncoloni, David; Rossi, Alessandro; Rossi, Simone

    2014-01-01

    While polarity-specific after-effects of monopolar transcranial direct current stimulation (tDCS) on corticospinal excitability are well-documented, modulation of vital parameters due to current spread through the brainstem is still a matter of debate, raising potential concerns about its use through the general public, as well as for neurorehabilitation purposes. We monitored online and after-effects of monopolar tDCS (primary motor cortex) in 10 healthy subjects by adopting a neuronavigated transcranial magnetic stimulation (TMS)/tDCS combined protocol. Motor evoked potentials (MEPs) together with vital parameters [e.g., blood pressure, heart-rate variability (HRV), and sympathovagal balance] were recorded and monitored before, during, and after anodal, cathodal, or sham tDCS. Ten MEPs, every 2.5-min time windows, were recorded from the right first dorsal interosseous (FDI), while 5-min epochs were used to record vital parameters. The protocol included 15 min of pre-tDCS and of online tDCS (anodal, cathodal, or sham). After-effects were recorded for 30 min. We showed a polarity-independent stabilization of cortical excitability level, a polarity-specific after-effect for cathodal and anodal stimulation, and an absence of persistent excitability changes during online stimulation. No significant effects on vital parameters emerged both during and after tDCS, while a linear increase in systolic/diastolic blood pressure and HRV was observed during each tDCS condition, as a possible unspecific response to experimental demands. Taken together, current findings provide new insights on the safety of monopolar tDCS, promoting its application both in research and clinical settings. PMID:25101009

  9. "Making strange": a role for the humanities in medical education.

    PubMed

    Kumagai, Arno K; Wear, Delese

    2014-07-01

    Stories, film, drama, and art have been used in medical education to enhance empathy, perspective-taking, and openness to "otherness," and to stimulate reflection on self, others, and the world. Yet another, equally important function of the humanities and arts in the education of physicians is that of "making strange"-that is, portraying daily events, habits, practices, and people through literature and the arts in a way that disturbs and disrupts one's assumptions, perspectives, and ways of acting so that one sees the self, others, and the world anew. Tracing the development of this concept from Viktor Shklovsky's "enstrangement" (ostranenie) through Bertolt Brecht's "alienation effect," this essay describes the use of this technique to disrupt the "automaticity of thinking" in order to discover new ways of perceiving and being in the world.Enstrangement may be used in medical education in order to stimulate critical reflection and dialogue on assumptions, biases, and taken-for-granted societal conditions that may hinder the realization of a truly humanistic clinical practice. In addition to its ability to enhance one's critical understanding of medicine, the technique of "making strange" does something else: By disrupting fixed beliefs, this approach may allow a reexamination of patient-physician relationships in terms of human interactions and provide health care professionals an opportunity-an "open space"-to bear witness and engage with other individuals during challenging times. PMID:24751976

  10. Nanoscale visualization of functional adhesion/excitability nodes at the intercalated disc

    PubMed Central

    Leo-Macias, Alejandra; Agullo-Pascual, Esperanza; Sanchez-Alonso, Jose L.; Keegan, Sarah; Lin, Xianming; Arcos, Tatiana; Feng-Xia-Liang; Korchev, Yuri E.; Gorelik, Julia; Fenyö, David; Rothenberg, Eli; Delmar, Mario

    2016-01-01

    Intercellular adhesion and electrical excitability are considered separate cellular properties. Studies of myelinated fibres, however, show that voltage-gated sodium channels (VGSCs) aggregate with cell adhesion molecules at discrete subcellular locations, such as the nodes of Ranvier. Demonstration of similar macromolecular organization in cardiac muscle is missing. Here we combine nanoscale-imaging (single-molecule localization microscopy; electron microscopy; and ‘angle view' scanning patch clamp) with mathematical simulations to demonstrate distinct hubs at the cardiac intercalated disc, populated by clusters of the adhesion molecule N-cadherin and the VGSC NaV1.5. We show that the N-cadherin-NaV1.5 association is not random, that NaV1.5 molecules in these clusters are major contributors to cardiac sodium current, and that loss of NaV1.5 expression reduces intercellular adhesion strength. We speculate that adhesion/excitability nodes are key sites for crosstalk of the contractile and electrical molecular apparatus and may represent the structural substrate of cardiomyopathies in patients with mutations in molecules of the VGSC complex. PMID:26787348

  11. Modeling Spin Fluctuations and Magnetic Excitations from Time-Dependent Density Functional Theory

    NASA Astrophysics Data System (ADS)

    Gorni, Tommaso; Timrov, Iurii; Dal Corso, Andrea; Baroni, Stefano

    Harnessing spin fluctuations and magnetic excitations in materials is key in many fields of technology, spanning from memory devices to information transfer and processing, to name but a few. A proper understanding of the interplay between collective and single-particle spin excitations is still lacking, and it is expected that first-principle simulations based on TDDFT may shed light on this interplay, as well as on the role of important effects such as relativistic ones and related magnetic anisotropies. All the numerical approaches proposed so far to tackle this problem are based on the computationally demanding solution of the Sternheimer equations for the response orbitals or the even more demanding solution of coupled Dyson equations for the spin and charge susceptibilities. The Liouville-Lanczos approach to TDDFT has already proven to be a valuable alternative, the most striking of its features being the avoidance of sums over unoccupied single-particle states and the frequency-independence of the main numerical bottleneck. In this work we present an extension of this methodology to magnetic systems and its implementation in the Quantum ESPRESSO distribution, together with a few preliminary results on the magnon dispersions in bulk Fe.

  12. A simple model for the resonant vibrational excitation of molecules and the time evolution of electron-velocity distribution functions

    SciTech Connect

    Drallos, P.J.

    1989-01-01

    Part I. A simple model for the resonant vibrational excitation of a molecule by electron impact is proposed in which the potential curves of the electronic states of the molecule and its resonant anion are replaced by those of linear harmonic oscillators of arbitrary frequencies and equilibrium internuclear separations. A closed-form expression for the excitation amplitude is derived. Useful recursion relations among amplitudes are obtained which allow convenient evaluation of cross sections for vibrational excitation of Li{sub 2} and N{sub 2} by the impact of low energy electrons. Part II. A novel numerical technique for obtaining the time evolution of electron velocity and electron energy distribution functions in a gas in the presence of a uniform electric field is presented. Using this technique, the various swarm parameters can be evolved for sufficiently long times so that equilibrium can be reached without incurring any numerical instabilities. Results are presented for electron swarms in neon, argon, and a simple model gas, and also for positrons in neon.

  13. SEARCH FOR NUCLEI CONTAINING TWO STRANGE QUARKS.

    SciTech Connect

    MAY,M.

    1997-10-13

    This paper discusses a search for nuclei containing two strange quarks performed at Brookhaven National Laboratory. The goals and approach of experiment E885 are reviewed. Preliminary missing mass spectra for a subset of the data are presented, showing sensitivity for {Xi} hypernuclei and H particle searches. Existence of an angular correlation between pions in the sequential decay of {Lambda}{Lambda} hypernuclei is suggested on theoretical grounds.

  14. Strangeness and meson-nucleon sigma terms

    SciTech Connect

    Dahiya, Harleen; Sharma, Neetika

    2011-10-21

    The chiral constituent quark model ({chi}CQM) has been extended to calculate the flavor structure of the nucleon through the meson-nucleon sigma terms which have large contributions from the quark sea and are greatly affected by chiral symmetry breaking and SU(3) symmetry breaking. The hidden strangeness component in the nucleon has also been investigated and its significant contribution is found to be consistent with the recent available experimental observations.

  15. Electronically Excited States of Higher Acenes up to Nonacene: A Density Functional Theory/Multireference Configuration Interaction Study.

    PubMed

    Bettinger, Holger F; Tönshoff, Christina; Doerr, Markus; Sanchez-Garcia, Elsa

    2016-01-12

    While the optical spectra of the acene series up to pentacene provide textbook examples for the annulation principle, the spectra of the larger members are much less understood. The present work provides an investigation of the optically allowed excited states of the acene series from pentacene to nonacene, the largest acene observed experimentally, using the density functional based multireference configuration method (DFT/MRCI). For this purpose, the ten lowest energy states of the B2u and B3u irreducible representations were computed. In agreement with previous computational investigations, the electronic wave functions of the acenes acquire significant multireference character with increasing acene size. The HOMO → LUMO excitation is the major contributor to the (1)La state (p band, B2u) also for the larger acenes. The oscillator strength decreases with increasing length. The (1)Lb state (α band, B3u), so far difficult to assign for the larger acenes due to overlap with photoprecursor bands, becomes almost insensitive to acene length. The (1)Bb state (β band, B3u) also moves only moderately to lower energy with increasing acene size. Excited states of B3u symmetry that formally result from double excitations involving HOMO, HOMO-1, LUMO, and LUMO+1 decrease in energy much faster with system size. One of them (D1) has very small oscillator strength but becomes almost isoenergetic with the (1)La state for nonacene. The other (D2) also has low oscillator strength as long as it is higher in energy than (1)Bb. Once it is lower in energy than the (1)Bb state, both states interact strongly resulting in two states with large oscillator strengths. The emergence of two strongly absorbing states is in agreement with experimental observations. The DFT/MRCI computations reproduce experimental excitation energies very well for pentacene and hexacene (within 0.1 eV). For the larger acenes deviations are larger (up to 0.2 eV), but qualitative agreement is observed. PMID

  16. Dyadic Green's function of an ideal hard surface circular waveguide with application to excitation and scattering problems

    NASA Astrophysics Data System (ADS)

    Klymko, Victor A.; Yakovlev, Alexander B.; Eshrah, Islam A.; Kishk, Ahmed A.; Glisson, Allen W.

    2005-06-01

    Green's function analysis of ideal hard surface circular waveguides is proposed with application to excitation and scattering problems. A decomposition of the hard surface waveguide into perfect electric conductor and perfect magnetic conductor waveguides allows the representation of dyadic Green's function in terms of transverse electric (TE) and transverse magnetic (TM) waveguide modes, respectively. In addition, a term corresponding to a transverse electromagnetic (TEM) mode is included in the representation of the Green's dyadic. The TEM term is extracted in closed form from the eigenmode expansion of TM and TE modes in the zero-cutoff limit. The electric field distribution due to an arbitrarily oriented electric dipole source is illustrated for representative TM, TE, and TEM modes propagating in the ideal hard surface circular waveguide. The derived Green's function is used in the method of moments analysis of an ideal hard surface waveguide excited by a half-wavelength strip dipole antenna. In addition, the scattering of the TEM mode by a thin strip is studied in the ideal hard surface circular waveguide.

  17. [Density functional theory study of surface-enhanced raman spectra and excited state of 1,4-benzenedithiol].

    PubMed

    Shao, Yang-Fan; Li, Chong-Yang; Feng, Yuan-Ming; Lin, Wang

    2014-02-01

    Raman scattering spectra and optimized geometries of the 1,4-benzenedithiol molecule and complexes have been calculated using density functional theory (DFT) with B3LYP functional at the level of 6-311G+(d) basis set for C, H, S atoms and LanL2DZ for Ag, Au atoms, respectively. The optimized 1,4-benzenedithiol molecule was non-planar structure and the angle between benzene ring plane and S-H is 20.20. By means of the simulation of molecule adsorbed on gold and silver cluster, we concluded that gold clusters are nearly parallel to the benzenedithiol molecule and silver clusters are almost perpendicular to the molecular surface. The authors studied the interaction between Raman intensity and molecular properties, such as static polarizablity and charge distribution. The Raman intensity of 1,4-BDT-Au2, 1,4-BDT-Ag2 and Ag2-1,4-BDT-Au2 were in good agreement with static polarizability. The excited states of Ag2-1,4-BDT-Au2 complex were calculated using time-dependent density functional theory (TDDFT). And the simulated absorption spectra and several allowed singlet excited states were analyzed to investigate the surface-enhanced Raman chemical enhancement mechanism. PMID:24822413

  18. Genetically Encoded Optochemical Probes for Simultaneous Fluorescence Reporting and Light Activation of Protein Function with Two-Photon Excitation

    PubMed Central

    2014-01-01

    The site-specific incorporation of three new coumarin lysine analogues into proteins was achieved in bacterial and mammalian cells using an engineered pyrrolysyl-tRNA synthetase system. The genetically encoded coumarin lysines were successfully applied as fluorescent cellular probes for protein localization and for the optical activation of protein function. As a proof-of-principle, photoregulation of firefly luciferase was achieved in live cells by caging a key lysine residue, and excellent OFF to ON light-switching ratios were observed. Furthermore, two-photon and single-photon optochemical control of EGFP maturation was demonstrated, enabling the use of different, potentially orthogonal excitation wavelengths (365, 405, and 760 nm) for the sequential activation of protein function in live cells. These results demonstrate that coumarin lysines are a new and valuable class of optical probes that can be used for the investigation and regulation of protein structure, dynamics, function, and localization in live cells. The small size of coumarin, the site-specific incorporation, the application as both a light-activated caging group and as a fluorescent probe, and the broad range of excitation wavelengths are advantageous over other genetically encoded photocontrol systems and provide a precise and multifunctional tool for cellular biology. PMID:25341086

  19. Excitation functions for production of heavy actinides from interactions of /sup 16/O with /sup 249/Cf

    SciTech Connect

    Chasteler, R.M.; Henderson, R.A.; Lee, D.; Gregorich, K.E.; Nurmia, M.J.; Welch, R.B.; Hoffman, D.C.

    1987-11-01

    Excitation functions have been measured for the production of isotopes of Bk through Fm in bombardments of /sup 249/Cf with 90- to 150-MeV /sup 16/O ions. A comparison of the maxima of the mass-yield curves measured in this experiment with those for the reactions of /sup 18/O ions with /sup 249/Cf shows different shifts from those that have been measured for reactions of the /sup 16,18/O and /sup 20,22/Ne ion pairs with /sup 248/Cm. However, the shifts appear similar to those recently measured for reactions of these ion pairs with /sup 254/Es.

  20. Strangeness production in AA and pp collisions

    NASA Astrophysics Data System (ADS)

    Castorina, Paolo; Satz, Helmut

    2016-07-01

    Boost-invariant hadron production in high-energy collisions occurs in causally disconnected regions of finite space-time size. As a result, globally conserved quantum numbers (charge, strangeness, baryon number) are conserved locally in spatially restricted correlation clusters. Their size is determined by two time scales: the equilibration time specifying the formation of a quark-gluon plasma, and the hadronization time, specifying the onset of confinement. The expected values for these scales provide the theoretical basis for the suppression observed for strangeness production in elementary interactions ( pp , e^+e^- below LHC energies. In contrast, the space-time superposition of individual collisions in high-energy heavy-ion interactions leads to higher energy densities, resulting in much later hadronization and hence much larger hadronization volumes. This largely removes the causality constraints and results in an ideal hadronic resonance gas in full chemical equilibrium. In the present paper, we determine the collision energies needed for that; we also estimate when pp collisions reach comparable hadronization volumes and thus determine when strangeness suppression should disappear there as well.

  1. Strangeness in the baryon ground states

    NASA Astrophysics Data System (ADS)

    Semke, A.; Lutz, M. F. M.

    2012-10-01

    We compute the strangeness content of the baryon octet and decuplet states based on an analysis of recent lattice simulations of the BMW, PACS, LHPC and HSC groups for the pion-mass dependence of the baryon masses. Our results rely on the relativistic chiral Lagrangian and large-Nc sum rule estimates of the counter terms relevant for the baryon masses at N3LO. A partial summation is implied by the use of physical baryon and meson masses in the one-loop contributions to the baryon self energies. A simultaneous description of the lattice results of the BMW, LHPC, PACS and HSC groups is achieved. From a global fit we determine the axial coupling constants F ≃ 0.45 and D ≃ 0.80 in agreement with their values extracted from semi-leptonic decays of the baryons. Moreover, various flavor symmetric limits of baron octet and decuplet masses as obtained by the QCDSF-UKQCD group are recovered. We predict the pion- and strangeness sigma terms and the pion-mass dependence of the octet and decuplet ground states at different strange quark masses.

  2. Strangeness conservation constraints in hadron gas models

    SciTech Connect

    Tiwari, V.K.; Singh, S.K.; Uddin, S.; Singh, C.P.

    1996-05-01

    We examine the implications of the constraints arising due to strangeness conservation on the strangeness production in various existing thermal hadron-gas models. The dependence of strangeness chemical potential {mu}{sub {ital S}} on the baryon chemical potential {mu}{sub {ital B}} and temperature {ital T} is investigated. The incorporation of finite-size, hard-core, repulsive interactions in the thermodynamically consistent description of hot and dense hadron gas alters the results obtained for pointlike particles. We compare results in two extreme alternative cases: (1) {ital K} and {ital K}{sup {asterisk}} mesons are treated as point particles and they can penetrate all volumes occupied by baryons and antibaryons and (2) the volume occupied by the baryons and antibaryons is not accessible to them. We find that the results indeed depend on the assumptions made. Moreover, the anomalous results obtained for the ratios {bar {Xi}}/{Xi} and {bar {Lambda}}/{Lambda} rule out the second possibility. {copyright} {ital 1996 The American Physical Society.}

  3. Dynamics of laser excited colloidal gold nanoparticles functionalized with cysteine derivatives

    NASA Astrophysics Data System (ADS)

    Falamas, Alexandra; Tosa, Nicoleta; Tosa, Valer

    2015-09-01

    The ultrafast dynamics of Au colloidal nanoparticles excited with femtosecond laser pulses is investigated experimentally. The transient absorption signal presents a bleaching of the surface plasmon band and a transient absorption at the wings of the band. The kinetics of the "hot" electrons in Au nanoparticles show a fast component of around 1 ps and a slower one of approximately 300 ps. Additionally, we found that the time of the ground state population recovery of Au nanoparticles depends on the pump wavelength. Furthermore, the interaction of Au nanoparticles with cysteine and cystine is studied at different pump wavelengths. The increase of the ligand concentration produces a variation of the relaxation times, as well as a delay of the time zero kinetics due to the adsorption of the ligands to the Au surface.

  4. Strangeness asymmetry of the nucleon in the statistical parton model

    NASA Astrophysics Data System (ADS)

    Bourrely, Claude; Soffer, Jacques; Buccella, Franco

    2007-04-01

    We extend to the strange quarks and antiquarks, the statistical approach of parton distributions and we calculate the strange quark asymmetry s -sbar. We find that the asymmetry is small, positive in the low x region and negative in the high x region. In this framework, the polarized strange quarks and antiquarks distributions, which are obtained simultaneously, are found to be both negative for all x values.

  5. New excitation functions for proton induced reactions on natural titanium, nickel and copper up to 70 MeV

    NASA Astrophysics Data System (ADS)

    Garrido, E.; Duchemin, C.; Guertin, A.; Haddad, F.; Michel, N.; Métivier, V.

    2016-09-01

    New excitation functions for proton induced nuclear reactions on natural titanium, nickel and copper were measured, using the stacked-foil technique and gamma spectrometry, up to 70 MeV. The experimental cross sections were measured using the Ti-nat(p,x) V-48, Ni-nat(p,x) Ni-57 and Cu-nat(p,x) Zn-62,Co-56 monitor reactions recommended by the International Atomic Energy Agency (IAEA), depending on the investigated energy range. Data have been extracted for the Ti-nat(p,x) Sc-43,44m,46,47,48, V-48, K-42,43, Ni-nat(p,x) Ni-56,57, Co-55,56,57,58, Mn-52,54, Cu-nat(p,x) Cu-61,64, Ni-57, Co-56,57,58,60, Zn-62,65, Mn-54 reactions. Our results are discussed and compared to the existing ones as well as with the TALYS code version 1.6 calculations using default models. Our experimental data are in overall good agreement with the literature. TALYS is able to reproduce, in most cases, the experimental trend. Our new experimental results allow to expand our knowledge on these excitation functions, to confirm the existing trends and to give additional values on a large energy range. This work is in line with the new Coordinated Research Project (CRP) launched by the IAEA to expand the database of monitor reactions.

  6. Genetic Inhibition of CaMKII in Dorsal Striatal Medium Spiny Neurons Reduces Functional Excitatory Synapses and Enhances Intrinsic Excitability

    PubMed Central

    Klug, Jason R.; Mathur, Brian N.; Kash, Thomas L.; Wang, Hui-Dong; Matthews, Robert T.; Robison, A. J.; Anderson, Mark E.; Deutch, Ariel Y.; Lovinger, David M.; Colbran, Roger J.; Winder, Danny G.

    2012-01-01

    Ca2+/calmodulin-dependent protein kinase II (CaMKII) is abundant in striatal medium spiny neurons (MSNs). CaMKII is dynamically regulated by changes in dopamine signaling, as occurs in Parkinson's disease as well as addiction. Although CaMKII has been extensively studied in the hippocampus where it regulates excitatory synaptic transmission, relatively little is known about how it modulates neuronal function in the striatum. Therefore, we examined the impact of selectively overexpressing an EGFP-fused CaMKII inhibitory peptide (EAC3I) in striatal medium spiny neurons (MSNs) using a novel transgenic mouse model. EAC3I-expressing cells exhibited markedly decreased excitatory transmission, indicated by a decrease in the frequency of spontaneous excitatory postsynaptic currents (sEPSCs). This decrease was not accompanied by changes in the probability of release, levels of glutamate at the synapse, or changes in dendritic spine density. CaMKII regulation of the AMPA receptor subunit GluA1 is a major means by which the kinase regulates neuronal function in the hippocampus. We found that the decrease in striatal excitatory transmission seen in the EAC3I mice is mimicked by deletion of GluA1. Further, while CaMKII inhibition decreased excitatory transmission onto MSNs, it increased their intrinsic excitability. These data suggest that CaMKII plays a critical role in setting the excitability rheostat of striatal MSNs by coordinating excitatory synaptic drive and the resulting depolarization response. PMID:23028932

  7. Variational polaron self-interaction-corrected total-energy functional for charge excitations in insulators

    NASA Astrophysics Data System (ADS)

    Sadigh, Babak; Erhart, Paul; Ã berg, Daniel

    2015-08-01

    We conduct a detailed investigation of the polaron self-interaction (pSI) error in standard approximations to the exchange-correlation (XC) functional within density-functional theory (DFT). The pSI leads to delocalization error in the polaron wave function and energy, as calculated from the Kohn-Sham (KS) potential in the native charge state of the polaron. This constitutes the origin of the systematic failure of DFT to describe the polaron formation in band insulators. It is shown that the delocalization error in these systems is, however, largely absent in the KS potential of the closed-shell neutral charge state. This leads to a modification of the DFT total-energy functional that corrects the pSI in the XC functional. The resulting pSIC-DFT method constitutes an accurate parameter-free ab initio methodology for calculating polaron properties in insulators at a computational cost that is orders of magnitude smaller than hybrid XC functionals. Unlike approaches that rely on parametrized localized potentials such as DFT+U , the pSIC-DFT method properly captures both site and bond-centered polaron configurations. This is demonstrated by studying formation and migration of self-trapped holes in alkali halides (bond-centered) as well as self-trapped electrons in an elpasolite compound (site-centered). The pSIC-DFT approach consistently reproduces the results obtained by hybrid XC functionals parametrized by DFT+G0W0 calculations. Finally, we generalize the pSIC approach to hybrid functionals, and show that in stark contrast to conventional hybrid calculations of polaron energies, the pSIC-hybrid method is insensitive to the parametrization of the hybrid XC functional. On this basis, we further rationalize the success of the pSIC-DFT approach.

  8. {sup 35}Cl+{sup 12}C asymmetrical fission excitation functions

    SciTech Connect

    Beck, C.; Mahboub, D.; Nouicer, R.; Matsuse, T.; Djerroud, B.; Freeman, R.M.; Haas, F.; Hachem, A.; Morsad, A.; Youlal, M.; Dayras, R.; Wieleczko, J.P.; Berthoumieux, E.; Legrain, R.; Pollacco, E.

    1996-07-01

    The fully energy-damped yields from the {sup 35}Cl+{sup 12}C reaction have been systematically investigated using particle-particle coincidence techniques at a {sup 35}Cl bombarding energy of {approximately}8 MeV/nucleon. The fragment-fragment correlation data show that the majority of events arises from a binary-decay process with rather large numbers of secondary light-charged particles emitted from the two excited exit fragments. No evidence is observed for ternary break-up events. The binary-process results of the present measurement, along with those of earlier, inclusive experimental data obtained at several lower bombarding energies are compared with predictions of two different kinds of statistical model calculations. These calculations are performed using the transition-state formalism and the extended Hauser-Feshbach method and are based on the available phase space at the saddle point and scission point of the compound nucleus, respectively. The methods give comparable predictions and are both in good agreement with the experimental results thus confirming the fusion-fission origin of the fully damped yields. The similarity of the predictions for the two models supports the claim that the scission point configuration is very close to that of the saddle point for the light {sup 47}V compound system. The results also give further support for the specific mass-asymmetry-dependent fission barriers needed in the transition-state calculation. {copyright} {ital 1996 The American Physical Society.}

  9. New look at the [70,1{sup -}] nonstrange and strange baryons in the 1/N{sub c} expansion

    SciTech Connect

    Matagne, N.; Stancu, Fl.

    2011-05-23

    The masses of excited nonstrange and strange baryons belonging to the multiplet [70,1{sup -}] are calculated in the 1/N{sub c} expansion to order 1/N{sub c} with a new method which allows to considerably reduce the number of linearly independent operators entering the mass formula. This study represents an extension to SU(6) of our work on nonstrange baryons, the framework of which was SU(4).

  10. Does the regulation of local excitation-inhibition balance aid in recovery of functional connectivity? A computational account.

    PubMed

    Vattikonda, Anirudh; Surampudi, Bapi Raju; Banerjee, Arpan; Deco, Gustavo; Roy, Dipanjan

    2016-08-01

    Computational modeling of the spontaneous dynamics over the whole brain provides critical insight into the spatiotemporal organization of brain dynamics at multiple resolutions and their alteration to changes in brain structure (e.g. in diseased states, aging, across individuals). Recent experimental evidence further suggests that the adverse effect of lesions is visible on spontaneous dynamics characterized by changes in resting state functional connectivity and its graph theoretical properties (e.g. modularity). These changes originate from altered neural dynamics in individual brain areas that are otherwise poised towards a homeostatic equilibrium to maintain a stable excitatory and inhibitory activity. In this work, we employ a homeostatic inhibitory mechanism, balancing excitation and inhibition in the local brain areas of the entire cortex under neurological impairments like lesions to understand global functional recovery (across brain networks and individuals). Previous computational and empirical studies have demonstrated that the resting state functional connectivity varies primarily due to the location and specific topological characteristics of the lesion. We show that local homeostatic balance provides a functional recovery by re-establishing excitation-inhibition balance in all areas that are affected by lesion. We systematically compare the extent of recovery in the primary hub areas (e.g. default mode network (DMN), medial temporal lobe, medial prefrontal cortex) as well as other sensory areas like primary motor area, supplementary motor area, fronto-parietal and temporo-parietal networks. Our findings suggest that stability and richness similar to the normal brain dynamics at rest are achievable by re-establishment of balance. PMID:27177761

  11. Parallel transmit excitation at 1.5 T based on the minimization of a driving function for device heating

    PubMed Central

    Gudino, N.; Sonmez, M.; Yao, Z.; Baig, T.; Nielles-Vallespin, S.; Faranesh, A. Z.; Lederman, R. J.; Martens, M.; Balaban, R. S.; Hansen, M. S.; Griswold, M. A.

    2015-01-01

    Purpose: To provide a rapid method to reduce the radiofrequency (RF) E-field coupling and consequent heating in long conductors in an interventional MRI (iMRI) setup. Methods: A driving function for device heating (W) was defined as the integration of the E-field along the direction of the wire and calculated through a quasistatic approximation. Based on this function, the phases of four independently controlled transmit channels were dynamically changed in a 1.5 T MRI scanner. During the different excitation configurations, the RF induced heating in a nitinol wire immersed in a saline phantom was measured by fiber-optic temperature sensing. Additionally, a minimization of W as a function of phase and amplitude values of the different channels and constrained by the homogeneity of the RF excitation field (B1) over a region of interest was proposed and its results tested on the benchtop. To analyze the validity of the proposed method, using a model of the array and phantom setup tested in the scanner, RF fields and SAR maps were calculated through finite-difference time-domain (FDTD) simulations. In addition to phantom experiments, RF induced heating of an active guidewire inserted in a swine was also evaluated. Results: In the phantom experiment, heating at the tip of the device was reduced by 92% when replacing the body coil by an optimized parallel transmit excitation with same nominal flip angle. In the benchtop, up to 90% heating reduction was measured when implementing the constrained minimization algorithm with the additional degree of freedom given by independent amplitude control. The computation of the optimum phase and amplitude values was executed in just 12 s using a standard CPU. The results of the FDTD simulations showed similar trend of the local SAR at the tip of the wire and measured temperature as well as to a quadratic function of W, confirming the validity of the quasistatic approach for the presented problem at 64 MHz. Imaging and heating

  12. Parallel transmit excitation at 1.5 T based on the minimization of a driving function for device heating

    SciTech Connect

    Gudino, N.; Sonmez, M.; Nielles-Vallespin, S.; Faranesh, A. Z.; Lederman, R. J.; Balaban, R. S.; Hansen, M. S.; Yao, Z.; Baig, T.; Martens, M.; Griswold, M. A.

    2015-01-15

    Purpose: To provide a rapid method to reduce the radiofrequency (RF) E-field coupling and consequent heating in long conductors in an interventional MRI (iMRI) setup. Methods: A driving function for device heating (W) was defined as the integration of the E-field along the direction of the wire and calculated through a quasistatic approximation. Based on this function, the phases of four independently controlled transmit channels were dynamically changed in a 1.5 T MRI scanner. During the different excitation configurations, the RF induced heating in a nitinol wire immersed in a saline phantom was measured by fiber-optic temperature sensing. Additionally, a minimization of W as a function of phase and amplitude values of the different channels and constrained by the homogeneity of the RF excitation field (B{sub 1}) over a region of interest was proposed and its results tested on the benchtop. To analyze the validity of the proposed method, using a model of the array and phantom setup tested in the scanner, RF fields and SAR maps were calculated through finite-difference time-domain (FDTD) simulations. In addition to phantom experiments, RF induced heating of an active guidewire inserted in a swine was also evaluated. Results: In the phantom experiment, heating at the tip of the device was reduced by 92% when replacing the body coil by an optimized parallel transmit excitation with same nominal flip angle. In the benchtop, up to 90% heating reduction was measured when implementing the constrained minimization algorithm with the additional degree of freedom given by independent amplitude control. The computation of the optimum phase and amplitude values was executed in just 12 s using a standard CPU. The results of the FDTD simulations showed similar trend of the local SAR at the tip of the wire and measured temperature as well as to a quadratic function of W, confirming the validity of the quasistatic approach for the presented problem at 64 MHz. Imaging and heating

  13. Functional Modulation of Corticospinal Excitability with Adaptation of Wrist Movements to Novel Dynamical Environments

    PubMed Central

    Hirashima, Masaya

    2014-01-01

    Adaptation of reaching movements to a novel dynamic environment is associated with changes in neuronal activity in the primary motor cortex (M1), suggesting that M1 neurons are part of the internal model. Here, we investigated whether such changes in neuronal activity, resulting from motor adaptation, were also accompanied by changes in human corticospinal excitability, which reflects M1 activity at a macroscopic level. Participants moved a cursor on a display using the right wrist joint from the starting position toward one of eight equally spaced peripheral targets. Motor-evoked potentials (MEPs) were elicited from the wrist muscles by transcranial magnetic stimulation delivered over the left M1 before and after adaptation to a clockwise velocity-dependent force field. We found that the MEP elicited even during the preparatory period exhibited a directional tuning property, and that the preferred direction shifted clockwise after adaptation to the force field. In a subsequent experiment, participants simultaneously adapted an identical wrist movement to two opposing force fields, each of which was associated with unimanual or bimanual contexts, and the MEP during the preparatory period was flexibly modulated, depending on the context. In contrast, such modulation of the MEP was not observed when participants tried to adapt to two opposing force fields that were each associated with a target color. These results suggest that the internal model formed in the M1 is retrieved flexibly even during the preparatory period, and that the MEP could be a very useful probe for evaluating the formation and retrieval of motor memory. PMID:25209281

  14. Strange baryonic resonances and resonances coupling to strange hadrons at SIS energies

    NASA Astrophysics Data System (ADS)

    Fabbietti, L.

    2016-01-01

    The role played by baryonic resonances in the production of final states containing strangeness for proton-proton reactions at 3.5 GeV measured by HADES is discussed by means of several very different measurements. First the associate production of Δ resonances accompanying final states with strange hadrons is presented, then the role of interferences among N* resonances, as measured by HADES for the first time, is summarised. Last but not least the role played by heavy resonances, with a mass larger than 2 GeV/c2 in the production of strange and non-strange hadrons is discussed. Experimental evidence for the presence of a Δ(2000)++ are presented and hypotheses are discussed employing the contribution of similar objects to populate the excesses measured by HADES for the Ξ in A+A and p+A collisions and in the dilepton sector for A+A collisions. This extensive set of results helps to better understand the dynamic underlaying particle production in elementary reactions and sets a more solid basis for the understanding of heavy ion collisions at the same energies and even higher as planned at the FAIR facility.

  15. Confinement effects on excitation energies and regioselectivity as probed by the Fukui function and the molecular electrostatic potential

    NASA Astrophysics Data System (ADS)

    Borgoo, Alex; Tozer, David; Geerlings, Paul; de Proft, Frank

    2009-03-01

    When a molecule is placed as a guest inside a zeolite pore, its electronic structure will be altered, among others by the effect of the so-called ``confinement". It has been established that the compression of the molecular orbitals influences a system's reactivity. In this work we use a simple potential barrier method to quantify the importance of confinement effects on chemical reactivity. In the first part, excitation energies and molecular orbital energy gaps are evaluated for molecules placed in cavities of different sizes. Our results for ethylene and formaldehyde reveal an increase in excitation energy and the gap between the occupied and the unoccupied levels. In the case of the larger molecules naphthalene and anthracene, the HOMO-LUMO gap shows very little sensitivity to the confinement. To investigate the role of confinement effects on local aspects of chemical reactivity and on regioselectivity, we evaluated its effect on the Fukui function and the molecular electrostatic potential, reactivity indices that are central in the description of orbital and charge controlled reactions. The results indicate that confinement can influence the regioselectivity and that the reactivity of anions is expected to change, due to the artificial binding of the exess electron.

  16. Tailoring the optimal control cost function to a desired output: application to minimizing phase errors in short broadband excitation pulses

    NASA Astrophysics Data System (ADS)

    Skinner, Thomas E.; Reiss, Timo O.; Luy, Burkhard; Khaneja, Navin; Glaser, Steffen J.

    2005-01-01

    The de facto standard cost function has been used heretofore to characterize the performance of pulses designed using optimal control theory. The freedom to choose new, creative quality factors designed for specific purposes is demonstrated. While the methodology has more general applicability, its utility is illustrated by comparison to a consistently chosen example—broadband excitation. The resulting pulses are limited to the same maximum RF amplitude used previously and tolerate the same variation in RF homogeneity deemed relevant for standard high-resolution NMR probes. Design criteria are unchanged: transformation of Iz → Ix over resonance offsets of ±20 kHz and RF variability of ±5%, with a peak RF amplitude equal to 17.5 kHz. However, the new cost effectively trades a small increase in residual z magnetization for improved phase in the transverse plane. Compared to previous broadband excitation by optimized pulses (BEBOP), significantly shorter pulses are achievable, with only marginally reduced performance. Simulations transform Iz to greater than 0.98 Ix, with phase deviations of the final magnetization less than 2°, over the targeted ranges of resonance offset and RF variability. Experimental performance is in excellent agreement with the simulations.

  17. Altered Kv2.1 functioning promotes increased excitability in hippocampal neurons of an Alzheimer's disease mouse model.

    PubMed

    Frazzini, V; Guarnieri, S; Bomba, M; Navarra, R; Morabito, C; Mariggiò, M A; Sensi, S L

    2016-01-01

    Altered neuronal excitability is emerging as an important feature in Alzheimer's disease (AD). Kv2.1 potassium channels are important modulators of neuronal excitability and synaptic activity. We investigated Kv2.1 currents and its relation to the intrinsic synaptic activity of hippocampal neurons from 3xTg-AD (triple transgenic mouse model of Alzheimer's disease) mice, a widely employed preclinical AD model. Synaptic activity was also investigated by analyzing spontaneous [Ca(2+)]i spikes. Compared with wild-type (Non-Tg (non-transgenic mouse model)) cultures, 3xTg-AD neurons showed enhanced spike frequency and decreased intensity. Compared with Non-Tg cultures, 3xTg-AD hippocampal neurons revealed reduced Kv2.1-dependent Ik current densities as well as normalized conductances. 3xTg-AD cultures also exhibited an overall decrease in the number of functional Kv2.1 channels. Immunofluorescence assay revealed an increase in Kv2.1 channel oligomerization, a condition associated with blockade of channel function. In Non-Tg neurons, pharmacological blockade of Kv2.1 channels reproduced the altered pattern found in the 3xTg-AD cultures. Moreover, compared with untreated sister cultures, pharmacological inhibition of Kv2.1 in 3xTg-AD neurons did not produce any significant modification in Ik current densities. Reactive oxygen species (ROS) promote Kv2.1 oligomerization, thereby acting as negative modulator of the channel activity. Glutamate receptor activation produced higher ROS levels in hippocampal 3xTg-AD cultures compared with Non-Tg neurons. Antioxidant treatment with N-Acetyl-Cysteine was found to rescue Kv2.1-dependent currents and decreased spontaneous hyperexcitability in 3xTg-AD neurons. Analogous results regarding spontaneous synaptic activity were observed in neuronal cultures treated with the antioxidant 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox). Our study indicates that AD-related mutations may promote enhanced ROS generation, oxidative

  18. METHODOLOGICAL NOTES: Strange attractors in rattleback dynamics

    NASA Astrophysics Data System (ADS)

    Borisov, Aleksei V.; Mamaev, Ivan S.

    2003-04-01

    This review is dedicated to the dynamics of the rattleback, a phenomenon with curious physical properties that is studied in nonholonomic mechanics. All known analytical results are collected here, and some results of our numerical simulation are presented. In particular, three-dimensional Poincare maps associated with dynamical systems are systematically investigated for the first time. It is shown that the loss of stability of periodic and quasiperiodic solutions, which gives rise to strange attractors, is typical of the three-dimensional maps related to rattleback dynamics. This explains some newly discovered properties of the rattleback related to the transition from regular to chaotic solutions at certain values of the physical parameters.

  19. Strange Quark Matter Status and Prospects

    NASA Technical Reports Server (NTRS)

    Sandweiss, J.

    2004-01-01

    The existence of quark states with more than three quarks is allowed in QCD. The stability of such quark matter states has been studied with lattice QCD and phenomenological bag models, but is not well constrained by theory. The addition of strange quarks to the system allows the quarks to be in lower energy states despite the additional mass penalty. There is additional stability from reduced Coulomb repulsion. SQM is expected to have a low Z/A. Stable or metastable massive multiquark states contain u, d, and s quarks.

  20. HD 207739 - A strange composite star

    NASA Technical Reports Server (NTRS)

    Parsons, S. B.; Holm, A. V.; Kondo, Y.

    1983-01-01

    This star, classified F8 IIe + B:, has a very unusual ultraviolet spectrum, with abnormally strong and numerous absorption features in the far-UV and exceptionally strong Mg II emission. There is some resemblance to shell and pre-main-sequence B stars, but it more closely matches the strange spectra of the eclipsing systems VV Cep and SX Cas, and it probably has considerable circumstellar material at fairly high temperature. HD 207739 is probably an interacting binary and needs to be monitored for light and velocity variations.

  1. Radial oscillations of charged strange stars

    NASA Astrophysics Data System (ADS)

    Arbañil, J. D. V.; Malheiro, M.

    2016-04-01

    The radial oscillations of charged strange quark stars is investigated. It is considered that the fluid pressure follows the MIT bag model equation of state and the charge density to be proportional to the energy density, ρe = αρ (where α is proportionality constant). The modified equations of radial oscillations to the introduction of the electric charge are integrated to determine the fundamental mode. It is found that the stability of the charged object decreases with the increment of the central energy density and with the growth of the charge fraction.

  2. Quark number susceptibilities, strangeness, and dynamical confinement

    NASA Astrophysics Data System (ADS)

    Gavai, Rajiv V.; Gupta, Sourendu

    2001-10-01

    We report the first results on the strange quark number susceptibility χs over a large range of temperatures, mainly in the plasma phase of QCD. χs jumps across the phase transition temperature Tc and grows rapidly with temperature above but close to Tc. For all quark masses and susceptibilities in the entire temperature range studied, we find a significant departure from ideal-gas values. We also observe a strong correlation between these quantities and the susceptibility in the pseudoscalar channel, supporting ideas of ``dynamical confinement'' in the high temperature phase of the QCD plasma.

  3. Strangeness Physics with CLAS at Jefferson Lab

    SciTech Connect

    Schumacher, Reinhard

    2010-08-05

    We review recent developments in strangeness photo- and electro- production off the proton and neutron, as investigated using CLAS in Hall B at Jefferson Lab. By measuring sufficient spin observables one can decompose the reaction mechanism into elementary amplitudes. We discuss progress toward this end in recent data from CLAS, including cross sections and spin observables. We next discuss new results on the mass distribution of the {Lambda}(1405), which shows signs of being a composite meson-baryon object of mixed isospin. The work on other hyperons such as the {Xi} resonances will be mentioned, and future prospects for the CLAS program outlined.

  4. Strangeness Physics with CLAS at Jefferson Lab

    SciTech Connect

    Reinhard Schumacher

    2010-08-01

    We review recent developments in strangeness photo- and electro- production off the proton and neutron, as investigated using CLAS in Hall B at Jefferson Lab. By measuring sufficient spin observables one can decompose the reaction mechanism into elementary amplitudes. We discuss progress toward this end in recent data from CLAS, including cross sections and spin observables. We next discuss new results on the mass distribution of the Lambda(1405), which shows signs of being a composite meson-baryon object of mixed isospin. The work on other hyperons such as the Xi resonances will be mentioned, and future prospects for the CLAS program outlined.

  5. A sudden change of a strange repeller

    NASA Astrophysics Data System (ADS)

    Ma, Ming-Quan; Wu, Shunguang; He, Da-Ren

    1998-03-01

    We have observed a transient chaos[1] after a boundary crisis in a simplified model of an impact oscillator. A strange repeller was found there and the scaling of the averaged life time was calculated both analytically and numerically. With the developing of the control parameter, the transient chaos was suddenly destroyed via a collision of a pair of the saddle nodes with a non-differential point of the mapping. The repeller disappeared and the scaling rules significantly changed as well after this collision. [1]:T.Tél, in ``Directions in Chaos'', vol.3, ed. by Hao Bai-lin, World Scientific Pub., Singapore, 1990.

  6. Seismic search for strange quark nuggets

    SciTech Connect

    Herrin, Eugene T.; Rosenbaum, Doris C.; Teplitz, Vigdor L.

    2006-02-15

    Bounds on masses and abundances of Strange Quark Nuggets (SQNs) are inferred from a seismic search on Earth. Potential SQN bounds from a possible seismic search on the Moon are reviewed and compared with Earth capabilities. Bounds are derived from the data taken by seismometers implanted on the Moon by the Apollo astronauts. We show that the Apollo data implies that the abundance of SQNs in the region of 10 kg to 1 ton must be at least an order of magnitude less than would saturate the dark matter in the solar neighborhood.

  7. Stability of charged strange quark stars

    SciTech Connect

    Arbañil, José D. V.; Malheiro, Manuel

    2015-12-17

    We investigate the hydrostatic equilibrium and the stability of charged stars made of a charged perfect fluid. The matter contained in the star follows the MIT bag model equation of state and the charge distribution to a power-law of the radial coordinate. The hydrostatic equilibrium and the stability of charged strange stars are analyzed using the Tolman-Oppenheimer-Volkoff equation and the Chandrasekhar’s equation pulsation, respectively. These two equation are modified from their original form to the inclusion of the electric charge. We found that the stability of the star decreases with the increment of the central energy density and with the increment of the amount of charge.

  8. Strangeness at high temperatures: from hadrons to quarks.

    PubMed

    Bazavov, A; Ding, H-T; Hegde, P; Kaczmarek, O; Karsch, F; Laermann, E; Maezawa, Y; Mukherjee, Swagato; Ohno, H; Petreczky, P; Schmidt, C; Sharma, S; Soeldner, W; Wagner, M

    2013-08-23

    Appropriate combinations of up to fourth order cumulants of net strangeness fluctuations and their correlations with net baryon number and electric charge fluctuations, obtained from lattice QCD calculations, have been used to probe the strangeness carrying degrees of freedom at high temperatures. For temperatures up to the chiral crossover, separate contributions of strange mesons and baryons can be well described by an uncorrelated gas of hadrons. Such a description breaks down in the chiral crossover region, suggesting that the deconfinement of strangeness takes place at the chiral crossover. On the other hand, the strangeness carrying degrees of freedom inside the quark gluon plasma can be described by a weakly interacting gas of quarks only for temperatures larger than twice the chiral crossover temperature. In the intermediate temperature window, these observables show considerably richer structures, indicative of the strongly interacting nature of the quark gluon plasma. PMID:24010429

  9. Universality in antiferromagnetic strange metals

    NASA Astrophysics Data System (ADS)

    Maier, Stefan A.; Strack, Philipp

    2016-04-01

    We propose a theory of metals at the spin-density-wave quantum-critical point in spatial dimension d =2 . We provide a first estimate of the full set of critical exponents (dynamical exponent z =2.13 , correlation length ν =1.02 , spin susceptibility γ =0.96 , electronic non-Fermi liquid ητf=0.53 , spin-wave Landau damping ητb=1.06 ), which determine the universal power laws in thermodynamics and response functions in the quantum-critical regime relevant for experiments in heavy-fermion systems and iron pnictides. We present approximate numerical and analytical solutions of Polchinski-Wetterich-type flow equations with soft frequency regulators for an effective action of electrons coupled to spin-wave bosons. Performing the renormalization group in frequency instead of momentum space allows to track changes of the Fermi-surface shape and to capture Landau damping during the flow. The technique is easily generalizable from models retaining only patches of the Fermi surface to full, compact Fermi surfaces.

  10. Mitochondrial Reactive Oxygen Species Production in Excitable Cells: Modulators of Mitochondrial and Cell Function

    PubMed Central

    Camara, Amadou K. S.

    2009-01-01

    Abstract The mitochondrion is a major source of reactive oxygen species (ROS). Superoxide (O2•−) is generated under specific bioenergetic conditions at several sites within the electron-transport system; most is converted to H2O2 inside and outside the mitochondrial matrix by superoxide dismutases. H2O2 is a major chemical messenger that, in low amounts and with its products, physiologically modulates cell function. The redox state and ROS scavengers largely control the emission (generation scavenging) of O2•−. Cell ischemia, hypoxia, or toxins can result in excess O2•− production when the redox state is altered and the ROS scavenger systems are overwhelmed. Too much H2O2 can combine with Fe2+ complexes to form reactive ferryl species (e.g., Fe(IV) = O•). In the presence of nitric oxide (NO•), O2•− forms the reactant peroxynitrite (ONOO−), and ONOOH-induced nitrosylation of proteins, DNA, and lipids can modify their structure and function. An initial increase in ROS can cause an even greater increase in ROS and allow excess mitochondrial Ca2+ entry, both of which are factors that induce cell apoptosis and necrosis. Approaches to reduce excess O2•− emission include selectively boosting the antioxidant capacity, uncoupling of oxidative phosphorylation to reduce generation of O2•− by inducing proton leak, and reversibly inhibiting electron transport. Mitochondrial cation channels and exchangers function to maintain matrix homeostasis and likely play a role in modulating mitochondrial function, in part by regulating O2•− generation. Cell-signaling pathways induced physiologically by ROS include effects on thiol groups and disulfide linkages to modify posttranslationally protein structure to activate/inactivate specific kinase/phosphatase pathways. Hypoxia-inducible factors that stimulate a cascade of gene transcription may be mediated physiologically by ROS. Our knowledge of the role played by ROS and their scavenging systems in

  11. Converging genetic and functional brain imaging evidence links neuronal excitability to working memory, psychiatric disease, and brain activity

    PubMed Central

    Heck, A.; Fastenrath, M.; Ackermann, S.; Auschra, B.; Bickel, H.; Coynel, D.; Gschwind, L.; Jessen, F.; Kaduszkiewicz, H.; Maier, W.; Milnik, A.; Pentzek, M.; Riedel-Heller, S.G.; Ripke, S.; Spalek, K.; Sullivan, P.; Vogler, C.; Wagner, M.; Weyerer, S.; Wolfsgruber, S.; de Quervain, D.; Papassotiropoulos, A.

    2014-01-01

    Summary Working memory, the capacity of actively maintaining task-relevant information during a cognitive task, is a heritable trait. Working memory deficits are characteristic for many psychiatric disorders. We performed genome-wide gene-set enrichment analyses in multiple independent data sets of young and aged cognitively healthy subjects (n = 2’824), and in a large schizophrenia case-control sample (n = 32’143). The voltage-gated cation channel activity gene-set, consisting of genes related to neuronal excitability, was robustly linked to performance in working memory-related tasks across ages, and to schizophrenia. Functional brain imaging in 707 healthy participants linked this gene-set also to working memory-related activity in the parietal cortex and the cerebellum. Gene-set analyses may help to dissect the molecular underpinnings of cognitive dimensions, brain activity and psychopathology. PMID:24529980

  12. Converging genetic and functional brain imaging evidence links neuronal excitability to working memory, psychiatric disease, and brain activity.

    PubMed

    Heck, Angela; Fastenrath, Matthias; Ackermann, Sandra; Auschra, Bianca; Bickel, Horst; Coynel, David; Gschwind, Leo; Jessen, Frank; Kaduszkiewicz, Hanna; Maier, Wolfgang; Milnik, Annette; Pentzek, Michael; Riedel-Heller, Steffi G; Ripke, Stephan; Spalek, Klara; Sullivan, Patrick; Vogler, Christian; Wagner, Michael; Weyerer, Siegfried; Wolfsgruber, Steffen; de Quervain, Dominique J-F; Papassotiropoulos, Andreas

    2014-03-01

    Working memory, the capacity of actively maintaining task-relevant information during a cognitive task, is a heritable trait. Working memory deficits are characteristic for many psychiatric disorders. We performed genome-wide gene set enrichment analyses in multiple independent data sets of young and aged cognitively healthy subjects (n = 2,824) and in a large schizophrenia case-control sample (n = 32,143). The voltage-gated cation channel activity gene set, consisting of genes related to neuronal excitability, was robustly linked to performance in working memory-related tasks across ages and to schizophrenia. Functional brain imaging in 707 healthy participants linked this gene set also to working memory-related activity in the parietal cortex and the cerebellum. Gene set analyses may help to dissect the molecular underpinnings of cognitive dimensions, brain activity, and psychopathology. PMID:24529980

  13. Excitation functions of alpha particle induced reactions on natTi up to 40 MeV

    NASA Astrophysics Data System (ADS)

    Uddin, M. S.; Scholten, B.

    2016-08-01

    Excitation functions of the reactions natTi(α,x)48Cr, natTi(α,x)48V and natTi(α,x)46,48Sc were determined by the stacked-foil activation technique up to 40 MeV. The radioactivities produced in the natTi target were measured by γ-ray spectrometry using HPGe detector. The reaction natTi(α,x)51Cr was used to determine the beam parameters. New experimental values for the above reactions have been obtained. An intercomparison of our data with the available literature values has been done. The cross section results obtained in this work could be useful in defining new monitor reactions, radiation safety and isotope production.

  14. Measurement of excitation functions in proton induced reactions on natural copper from their threshold to 43 MeV

    NASA Astrophysics Data System (ADS)

    Shahid, Muhammad; Kim, Kwangsoo; Naik, Haladhara; Zaman, Muhammad; Yang, Sung-Chul; Kim, Guinyun

    2015-01-01

    We have measured the production cross-sections of the residual radionuclides from proton-induced reactions of natCu by using a stacked-foil activation and off-line γ-ray spectrometric technique in the energy range from their respective threshold to 43 MeV at the MC-50 cyclotron of the Korea Institute of Radiological and Medical Sciences. The measured results were compared with the earlier reported data as well as with the theoretical values obtained from the TENDL-2013 library based on the TALYS 1.6 code. The integral yields for thick target of the investigated radio-nuclides were calculated from the measured excitation function and the stopping power of natCu.

  15. Measurement and theoretical analysis of the excitation functions for 3He induced reactions on natSn

    NASA Astrophysics Data System (ADS)

    Ali, B. M.; Al-Abyad, M.; Seddik, U.; El-Kameesy, S. U.; Ditrói, F.; Takács, S.; Tárkányi, F.

    2015-11-01

    Excitation functions of 3He induced nuclear reactions on natSn were measured up to 26 MeV using the stacked-foil technique, utilizing the MGC-20E cyclotron of ATOMKI. Using HPGe detector the following radioisotopes were identified: 116,117,118,119g,119m,121g,121m,123mTe, 115g,116m,117,118m,120m,122g,124gSb and 113g,117mSn. The experimental results are presented for the first time in this energy range. The results of theoretical calculations based on EMPIRE and TENDL library were compared with the present data. Integral yields for some isotopes were calculated.

  16. Excitation functions for production of radioisotopes of niobium, zirconium and yttrium by irradiation of zirconium with deuterons

    NASA Astrophysics Data System (ADS)

    Tárkányi, F.; Hermanne, A.; Takács, S.; Ditrói, F.; Dityuk, A. I.; Shubin, Yu. N.

    2004-05-01

    Excitation functions of deuteron-induced reactions on natural zirconium were re-measured up to 50 MeV for the natZr(d,x) 90,91m,92m,95,96Nb, natZr(d,x) 88,89,95,97Zr and natZr(d,x) 86,87,88Y reactions. A physically accurate activation method on stacks of natural zirconium foils was used. The results were critically compared with a detailed compilation of earlier reported experimental data and with theoretical calculations. In the overlapping energy regions mainly acceptable agreement was found or our data complete the database where contradictory or scarce data were available. The possible alternative uses in medically relevant radionuclide production as well as applications in thin layer activation and dosimetry are discussed.

  17. Comparative assessment of density functional methods for evaluating essential parameters to simulate SERS spectra within the excited state energy gradient approximation

    NASA Astrophysics Data System (ADS)

    Mohammadpour, Mozhdeh; Jamshidi, Zahra

    2016-05-01

    The prospect of challenges in reproducing and interpretation of resonance Raman properties of molecules interacting with metal clusters has prompted the present research initiative. Resonance Raman spectra based on the time-dependent gradient approximation are examined in the framework of density functional theory using different methods for representing the exchange-correlation functional. In this work the performance of different XC functionals in the prediction of ground state properties, excitation state energies, and gradients are compared and discussed. Resonance Raman properties based on time-dependent gradient approximation for the strongly low-lying charge transfer states are calculated and compared for different methods. We draw the following conclusions: (1) for calculating the binding energy and ground state geometry, dispersion-corrected functionals give the best performance in comparison to ab initio calculations, (2) GGA and meta GGA functionals give good accuracy in calculating vibrational frequencies, (3) excited state energies determined by hybrid and range-separated hybrid functionals are in good agreement with EOM-CCSD calculations, and (4) in calculating resonance Raman properties GGA functionals give good and reasonable performance in comparison to the experiment; however, calculating the excited state gradient by using the hybrid functional on the hessian of GGA improves the results of the hybrid functional significantly. Finally, we conclude that the agreement of charge-transfer surface enhanced resonance Raman spectra with experiment is improved significantly by using the excited state gradient approximation.

  18. Comparative assessment of density functional methods for evaluating essential parameters to simulate SERS spectra within the excited state energy gradient approximation.

    PubMed

    Mohammadpour, Mozhdeh; Jamshidi, Zahra

    2016-05-21

    The prospect of challenges in reproducing and interpretation of resonance Raman properties of molecules interacting with metal clusters has prompted the present research initiative. Resonance Raman spectra based on the time-dependent gradient approximation are examined in the framework of density functional theory using different methods for representing the exchange-correlation functional. In this work the performance of different XC functionals in the prediction of ground state properties, excitation state energies, and gradients are compared and discussed. Resonance Raman properties based on time-dependent gradient approximation for the strongly low-lying charge transfer states are calculated and compared for different methods. We draw the following conclusions: (1) for calculating the binding energy and ground state geometry, dispersion-corrected functionals give the best performance in comparison to ab initio calculations, (2) GGA and meta GGA functionals give good accuracy in calculating vibrational frequencies, (3) excited state energies determined by hybrid and range-separated hybrid functionals are in good agreement with EOM-CCSD calculations, and (4) in calculating resonance Raman properties GGA functionals give good and reasonable performance in comparison to the experiment; however, calculating the excited state gradient by using the hybrid functional on the hessian of GGA improves the results of the hybrid functional significantly. Finally, we conclude that the agreement of charge-transfer surface enhanced resonance Raman spectra with experiment is improved significantly by using the excited state gradient approximation. PMID:27208944

  19. Calculations of Excitation Functions of Some Structural Fusion Materials for ( n, t) Reactions up to 50 MeV Energy

    NASA Astrophysics Data System (ADS)

    Tel, E.; Durgu, C.; Aktı, N. N.; Okuducu, Ş.

    2010-06-01

    Fusion serves an inexhaustible energy for humankind. Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, there is still a long way to go to penetrate commercial fusion reactors to the energy market. Tritium self-sufficiency must be maintained for a commercial power plant. For self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. So, the working out the systematics of ( n, t) reaction cross sections is of great importance for the definition of the excitation function character for the given reaction taking place on various nuclei at different energies. In this study, ( n, t) reactions for some structural fusion materials such as 27Al, 51V, 52Cr, 55Mn, and 56Fe have been investigated. The new calculations on the excitation functions of 27Al( n, t)25Mg, 51V( n, t)49Ti, 52Cr( n, t)50V, 55Mn( n, t)53Cr and 56Fe( n, t)54Mn reactions have been carried out up to 50 MeV incident neutron energy. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the new evaluated the geometry dependent hybrid model, hybrid model and the cascade exciton model. Equilibrium effects are calculated according to the Weisskopf-Ewing model. Also in the present work, we have calculated ( n, t) reaction cross-sections by using new evaluated semi-empirical formulas developed by Tel et al. at 14-15 MeV energy. The calculated results are discussed and compared with the experimental data taken from the literature.

  20. Investigation of effect of excitation frequency on electron energy distribution functions in low pressure radio frequency bounded plasmas

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Sudeep; Lafleur, Trevor; Charles, Christine; Boswell, Rod

    2011-07-01

    Particle in cell (PIC) simulations are employed to investigate the effect of excitation frequency ω on electron energy distribution functions (EEDFs) in a low pressure radio frequency (rf) discharge. The discharge is maintained over a length of 0.10 m, bounded by two infinite parallel plates, with the coherent heating field localized at the center of the discharge over a distance of 0.05 m and applied perpendicularly along the y and z directions. On varying the excitation frequency f (=ω/2π) in the range 0.01-50 MHz, it is observed that for f ≤ 5 MHz the EEDF shows a trend toward a convex (Druyvesteyn-like) distribution. For f > 5 MHz, the distribution resembles more like a Maxwellian with the familiar break energy visible in most of the distributions. A prominent "hot tail" is observed at f ≥ 20 MHz and the temperature of the tail is seen to decrease with further increase in frequency (e.g., at 30 MHz and 50 MHz). The mechanism for the generation of the "hot tail" is considered to be due to preferential transit time heating of energetic electrons as a function of ω, in the antenna heating field. There exists an optimum frequency for which high energy electrons are maximally heated. The occurrence of the Druyvesteyn-like distributions at lower ω may be explained by a balance between the heating of the electrons in the effective electric field and elastic cooling due to electron neutral collision frequency νen; the transition being dictated by ω ˜ 2πνen.

  1. Investigations of the potential functions of weakly bound diatomic molecules and laser-assisted excitive Penning ionization

    SciTech Connect

    Goble, J.H. Jr.

    1982-05-01

    Three variations on the Dunham series expansion function of the potential of a diatomic molecule are compared. The differences among these expansions lie in the choice of the expansion variable, lambda. The functional form of these variables are lambda/sub s/ = l-r/sub e//r for the Simon-Parr-Finlan version, lambda/sub T/ - 1-(r/sub e//r)/sup p/ for that of Thakkar, and lambda/sub H/ = 1-exp(-rho(r/r/sub e/-1) for that of Huffaker. A wide selection of molecular systems are examined. It is found that, for potentials in excess of thirty kcal/mole, the Huffaker expansion provides the best description of the three, extrapolating at large internuclear separation to a value within 10% of the true dissociation energy. For potentials that result from the interaction of excited states, all series expansions show poor behavior away from the equilibrium internuclear separation of the molecule. The series representation of the potentials of weakly bound molecules are examined in more detail. The ground states of BeAr/sup +/, HeNe/sup +/, NaAr, and Ar/sub 2/ and the excited states of HeNe+, NaNe, and NaAr are best described by the Thakkar expansion. Finally, the observation of laser-assisted excitive Penning ionization in a flowing afterglow is reported. The reaction Ar(/sup 3/P/sub 2/) + Ca + h nu ..-->.. Ar + Ca/sup +/(5p /sup 2/P/sub J/) + e/sup -/ occurs when the photon energy, h nu, is approximately equal to the energy difference between the metastable argon and one of the fine structure levels of the ion's doublet. By monitoring the cascade fluorescence of the above reaction and comparing it to the flourescence from the field-free process Ar(/sup 3/P/sub 2/) + Ca ..-->.. Ar + Ca/sup +/(4p /sup 2/P/sub J/) + e/sup -/ a surprisingly large cross section of 6.7 x 10/sup 3/ A/sup 2/ is estimated.

  2. Ionisation potential theorem in the presence of the electric field: Assessment of range-separated functional in the reproduction of orbital and excitation energies

    NASA Astrophysics Data System (ADS)

    Borpuzari, Manash Protim; Boruah, Abhijit; Kar, Rahul

    2016-04-01

    Recently, the range-separated density functionals have been reported to reproduce gas phase orbital and excitation energies with good accuracy. In this article, we have revisited the ionisation potential theorem in the presence of external electric field. Numerical results on six linear molecules are presented and the performance of the range-separated density functionals in reproducing highest occupied molecular orbital (HOMO) energies, LUMO energies, HOMO-LUMO gaps in the presence of the external electric field is assessed. In addition, valence and Rydberg excitation energies in the presence of the external electric field are presented. It is found that the range-separated density functionals reproduce orbital and excitation energies accurately in the presence of the electric field. Moreover, we have performed fractional occupation calculation using cubic spline equation and tried to explain the performance of the functional.

  3. Corticospinal excitability as a predictor of functional gains at the affected upper limb following robotic training in chronic stroke survivors

    PubMed Central

    Milot, Marie-Hélène; Spencer, Steven J.; Chan, Vicky; Allington, James P.; Klein, Julius; Chou, Cathy; Pearson-Fuhrhop, Kristin; Bobrow, James E.; Reinkensmeyer, David J.; Cramer, Steven C.

    2014-01-01

    Background Robotic training can help improve function of a paretic limb following a stroke, but individuals respond differently to the training. A predictor of functional gains might improve the ability to select those individuals more likely to benefit from robot based therapy. Studies evaluating predictors of functional improvement after a robotic training are scarce. One study has found that white matter tract integrity predicts functional gains following a robotic training of the hand and wrist. Objective Determine the predictive ability of behavioral and brain measures to improve selection of individuals for robotic training. Methods Twenty subjects with chronic stroke participated in an 8-week course of robotic exoskeletal training for the arm. Before training, a clinical evaluation, fMRI, diffusion tensor imaging, and transcranial magnetic stimulation (TMS) were each measured as predictors. Final functional gain was defined as change in the Box and Block Test (BBT). Measures significant in bivariate analysis were fed into a multivariate linear regression model. Results Training was associated with an average gain of 6±5 blocks on the BBT (p<0.0001). Bivariate analysis revealed that lower baseline motor evoked potential (MEP) amplitude on TMS, and lower laterality M1 index on fMRI each significantly correlated with greater BBT change. In the multivariate linear regression analysis, baseline MEP magnitude was the only measure that remained significant. Conclusion Subjects with lower baseline MEP magnitude benefited the most from robotic training of the affected arm. These subjects might have reserve remaining for the training to boost corticospinal excitability, translating into functional gains. PMID:24642382

  4. Density functional investigation of the electronic structure and charge transfer excited states of a multichromophoric antenna

    NASA Astrophysics Data System (ADS)

    Basurto, Luis; Zope, Rajendra R.; Baruah, Tunna

    2016-05-01

    We report an electronic structure study of a multichromophoric molecular complex containing two of each borondipyrromethane dye, Zn-tetraphenyl-porphyrin, bisphenyl anthracene and a fullerene. The snowflake shaped molecule behaves like an antenna capturing photon at different frequencies and transferring the photon energy to the porphyrin where electron transfer occurs from the porphyrin to the fullerene. The study is performed within density functional formalism using large polarized Guassian basis sets (12,478 basis functions in total). The energies of the HOMO and LUMO states in the complex, as adjudged by the ionization potential and the electron affinity values, show significant differences with respect to their values in participating subunits in isolation. These differences are also larger than the variations of the ionization potential and electron affinity values observed in non-bonded C60-ZnTPP complexes in co-facial arrangement or end-on orientations. An understanding of the origin of these differences is obtained by a systematic study of the effect of structural strain, the presence of ligands, the effect of orbital delocalization on the ionization energy and the electron affinity. Finally, a few lowest charge transfer energies involving electronic transitions from the porphyrin component to the fullerene subunit of the complex are predicted.

  5. Dilepton and strangeness production probed with HADES

    SciTech Connect

    Rustamov, A.

    2012-05-15

    With the High Acceptance Di-Electron Spectrometer (HADES) at GSI we have studied dilepton production in the few-GeV energy regime in various collisions systems, from elementary NN, over pA, up to the medium-heavy Ar + KCl system. We have thus confirmed the puzzling results of the former DLS Collaboration at the Bevalac. While we have traced the origin of the excess pair yield in CC collisions to elementary pp and pn processes, in our Ar + KCl data a contribution from the dense phase of the collision has been identified. Together with the e{sup +}e{sup -} pairs, we have also obtained in the Ar + KCl system at 1.76 A GeV a high-statistics data set on open and hidden strangeness, i.e. K{sup {+-}}, K{sub s}{sup 0}, {Lambda}, {phi}, and {Xi}{sup -}, allowing for a comprehensive discussion of strangeness production in this system.

  6. Notes on properties of holographic strange metals

    SciTech Connect

    Lee, Bum-Hoon; Pang, Da-Wei

    2010-11-15

    We investigate properties of holographic strange metals in p+2 dimensions, generalizing the analysis performed in [S. A. Hartnoll et al. J. High Energy Phys. 04 (2010) 120]. The bulk spacetime is a p+2-dimensional Lifshitz black hole, while the role of charge carriers is played by probe D-branes. We mainly focus on massless charge carriers, where most of the results can be obtained analytically. We obtain exact results for the free energy and calculate the entropy density and the heat capacity, as well as the speed of sound at low temperature. We obtain the DC conductivity and DC Hall conductivity and find that the DC conductivity takes a universal form in the large density limit, while the Hall conductivity is also universal in all dimensions. We also study the resistivity in different limits and clarify the condition for the linear dependence on the temperature, which is a key feature of strange metals. We show that our results for the DC conductivity are consistent with those obtained via the Kubo formula and we obtain the charge diffusion constant analytically. The corresponding properties of massive charge carriers are also discussed in brief.

  7. Strangeness electroproduction on the nucleon at CLAS

    SciTech Connect

    Daniel Carman

    2012-04-01

    High-precision measurements of strange particle production from both proton and neutron targets are a core part of the physics program with the CLAS spectrometer in Hall B at Jefferson Laboratory. Measurements have been carried out at beam energies up to 6 GeV in experiments with polarized beams and polarized targets. This talk will focus on the electroproduction measurements that have been completed, which include cross sections and hyperon polarization observables for K{sup +}Y (Y = {Lambda}{Sigma}{sup 0}) final states over a broad kinematic range in momentum transfer Q{sup 2} and invariant energy W, while spanning nearly the full kaon center-of-mass angular range. These data in the strangeness sector are necessary to better understand the different production mechanisms for {Lambda} and {Sigma} hyperons and to disentangle the different resonant and non-resonant amplitudes in the intermediate state. The usefulness of the CLAS electroproduction data as part of a coupled-channel model fit will be discussed as well as an outlook of this program for the future.

  8. Notes on properties of holographic strange metals

    NASA Astrophysics Data System (ADS)

    Lee, Bum-Hoon; Pang, Da-Wei

    2010-11-01

    We investigate properties of holographic strange metals in p+2 dimensions, generalizing the analysis performed in [S. A. Hartnoll J. High Energy Phys.JHEPFG1029-8479 04 (2010) 120]. The bulk spacetime is a p+2-dimensional Lifshitz black hole, while the role of charge carriers is played by probe D-branes. We mainly focus on massless charge carriers, where most of the results can be obtained analytically. We obtain exact results for the free energy and calculate the entropy density and the heat capacity, as well as the speed of sound at low temperature. We obtain the DC conductivity and DC Hall conductivity and find that the DC conductivity takes a universal form in the large density limit, while the Hall conductivity is also universal in all dimensions. We also study the resistivity in different limits and clarify the condition for the linear dependence on the temperature, which is a key feature of strange metals. We show that our results for the DC conductivity are consistent with those obtained via the Kubo formula and we obtain the charge diffusion constant analytically. The corresponding properties of massive charge carriers are also discussed in brief.

  9. Dual effect of local anesthetics on the function of excitable rod outer segment disk membrane

    SciTech Connect

    Mashimo, T.; Abe, K.; Yoshiya, I.

    1986-04-01

    The effects of local anesthetics and a divalent cation, Ca2+, on the function of rhodopsin were estimated from the measurements of light-induced proton uptake. The light-induced proton uptake by rhodopsin in the rod outer segment disk membrane was enhanced at lower pH (4) but depressed at higher pHs (6 to 8) by the tertiary amine local anesthetics lidocaine, bupivacaine, tetracaine, and dibucaine. The order of local anesthetic-induced depression of the proton uptake followed that of their clinical anesthetic potencies. The depression of the proton uptake versus the concentration of the uncharged form of local anesthetic nearly describes the same curve for small and large dose of added anesthetic. Furthermore, a neutral local anesthetic, benzocaine, depressed the proton uptake at all pHs between 4 and 7. These results indicate that the depression of the proton uptake is due to the effect of only the uncharged form. It is hypothesized that the uncharged form of local anesthetics interacts hydrophobically with the rhodopsin in the disk membrane. The dual effect of local anesthetics on the proton uptake, on the other hand, suggests that the activation of the function of rhodopsin may be caused by the charged form. There was no significant change in the light-induced proton uptake by rhodopsin when 1 mM of Ca2+ was introduced into the disk membrane at varying pHs in the absence or presence of local anesthetics. This fact indicates that Ca2+ ion does not influence the diprotonating process of metarhodopsin; neither does it interfere with the local anesthetic-induced changes in the rhodopsin molecule.

  10. Numerical study on a random 4-fermion interaction model of a strange metal

    NASA Astrophysics Data System (ADS)

    Fu, Wenbo; Sachdev, Subir

    We use exact diagonalization (ED) method to study the infinite range random 4 fermion model of a strange metal. We examine the Green's function and show that ED result is in agreement with the large N result in the scaling limit. We also examine the thermal entropy; this has an increasing trend as we increase the system size in the low temperature regime, and is consistent with large N high temperature expansion in the high temperature regime.

  11. Phenomenology of the three-flavor PNJL model and thermal strange quark production

    NASA Astrophysics Data System (ADS)

    Tsai, Hung-Ming; Müller, Berndt

    2009-07-01

    We study the temperature dependence of the adjoint Polyakov loop and its implication for the momentum spectrum of gluons in the mean-field approximation. This allows us to calculate the contribution of the thermal (transverse) gluons to the thermodynamic pressure. As an application, we evaluate the rates for the strange quark pair-production processes q\\barq \\tos\\bars and gg \\tos\\bars as functions of temperature including thermal effects on quark deconfinement and chiral symmetry breaking.

  12. Revisiting a magneto-elastic strange attractor

    NASA Astrophysics Data System (ADS)

    Tam, Jee Ian; Holmes, Philip

    2014-03-01

    We revisit an early example of a nonlinear oscillator that exhibits chaotic motions when subjected to periodic excitation: the magneto-elastically buckled beam. In the paper of Moons and Holmes (1980) [1] magnetic field calculations were outlined but not carried through; instead the nonlinear forces responsible for creation of a two-well potential and buckling were fitted to a polynomial function after reduction to a single mode model. In the present paper we compute the full magnetic field and use it to approximate the forces acting on the beam, also using a single mode reduction. This provides a complete model that accurately predicts equilibria, bifurcations, and free oscillation frequencies of an experimental device. We also compare some periodic, transient and chaotic motions with those obtained by numerical simulations of the single mode model, further illustrating the rich dynamical behavior of this simple electromechanical system.

  13. Cosmogenic nuclide production rates as a function of latitude and altitude calculated via a physics based model and excitation functions

    NASA Astrophysics Data System (ADS)

    Argento, D.; Reedy, R. C.; Stone, J. O.

    2012-12-01

    Cosmogenic nuclides have been used to develop a set of tools critical to the quantification of a wide range of geomorphic and climatic processes and events (Dunai 2010). Having reliable absolute measurement methods has had great impact on research constraining ice age extents as well as providing important climatic data via well constrained erosion rates, etc. Continuing to improve CN methods is critical for these sciences. While significant progress has been made in the last two decades to reduce uncertainties (Dunai 2010; Gosse & Phillips 2001), numerous aspects still need to be refined in order to achieve the analytic resolution desired by glaciologists and geomorphologists. In order to investigate the finer details of the radiation responsible for cosmogenic nuclide production, we have developed a physics based model which models the radiation cascade of primary and secondary cosmic-rays through the atmosphere. In this study, a Monte Carlo method radiation transport code, MCNPX, is used to model the galactic cosmic-ray (GCR) radiation impinging on the upper atmosphere. Beginning with a spectrum of high energy protons and alpha particles at the top of the atmosphere, the code tracks the primary and resulting secondary particles through a model of the Earth's atmosphere and into the lithosphere. Folding the neutron and proton flux results with energy dependent cross sections for nuclide production provides production rates for key cosmogenic nuclides (Argento et al. 2012, in press; Reedy 2012, in press). Our initial study for high latitude shows that nuclides scale at different rates for each nuclide (Argento 2012, in press). Furthermore, the attenuation length for each of these nuclide production rates increases with altitude, and again, they increase at different rates. This has the consequence of changing the production rate ratio as a function of altitude. The earth's geomagnetic field differentially filters low energy cosmic-rays by deflecting them away

  14. Strange Stars : An interesting member of the compact object family

    SciTech Connect

    Bagchi, Manjari; Ray, Subharthi; Dey, Jishnu; Dey, Mira

    2008-01-10

    We have studied strange star properties both at zero temperature and at finite temperatures and searched signatures of strange stars in gamma-ray, x-ray and radio astronomy. We have a set of Equations of State (EoS) for strange quark matter (SQM) and solving the TOV equations, we get the structure of strange stars. The maximum mass for a strange star decreases with the increase of temperature, because at high temperatures, the EoS become softer. One important aspect of strange star is that, surface tension depends on the size and structure of the star and is significantly larger than the conventional values. Moment of inertia is another important parameter for compact stars as by comparing theoretical values with observed estimate, it is possible to constrain the dense matter Equation of State. We hope that this approach will help us to decide whether the members of the double pulsar system PSR J0737-3039 are neutron stars or strange stars.

  15. Production of strange clusters in relativistic heavy ion collisions

    SciTech Connect

    Dover, C.B.; Baltz, A.J.; Pang, Yang; Schlagel, T.J.; Kahana, S.H.

    1993-02-01

    We address a number of issues related to the production of strangeness in high energy heavy ion collisions, including the possibility that stable states of multi-strange hyperonic or quark matter might exist, and the prospects that such objects may be created and detected in the laboratory. We make use of events generated by the cascade code ARC to estimate the rapidity distribution dN/dy of strange clusters produced in Si+Au and Au+Au collisions at AGS energies. These calculations are performed in a simple coalescence model, which yields a consistent description of the strange cluster (d, [sup 3]HE, [sup 3]H, [sup 4]He) production at these energies. If a doubly strange, weakly bound [Lambda][Lambda] dibaryon exists, we find that it is produced rather copiously in Au+Au collisions, with dN/dy [approximately]0.1 at raid-rapidity. If one adds another non-strange or strange baryon to a cluster, the production rate decreases by roughly one or two orders of magnitude, respectively. For instance, we predict that the hypernucleus [sub [Lambda][Lambda

  16. Assessment of the Global and Regional Land Hydrosphere and Its Impact on the Balance of the Geophysical Excitation Function of Polar Motion

    NASA Astrophysics Data System (ADS)

    Wińska, Małgorzata; Nastula, Jolanta; Kołaczek, Barbara

    2016-02-01

    The impact of continental hydrological loading from land water, snow and ice on polar motion excitation, calculated as hydrological angular momentum (HAM), is difficult to estimate, and not as much is known about it as about atmospheric angular momentum (AAM) and oceanic angular momentum (OAM). In this paper, regional hydrological excitations to polar motion are investigated using monthly terrestrial water storage data derived from the Gravity Recovery and Climate Experiment (GRACE) mission and from the five models of land hydrology. The results show that the areas where the variance shows large variability are similar for the different models of land hydrology and for the GRACE data. Areas which have a small amplitude on the maps make an important contribution to the global hydrological excitation function of polar motion. The comparison of geodetic residuals and global hydrological excitation functions of polar motion shows that none of the hydrological excitation has enough energy to significantly improve the agreement between the observed geodetic excitation and geophysical ones.

  17. Cell adhesion molecule L1 contributes to neuronal excitability regulating the function of voltage-gated Na+ channels.

    PubMed

    Valente, Pierluigi; Lignani, Gabriele; Medrihan, Lucian; Bosco, Federica; Contestabile, Andrea; Lippiello, Pellegrino; Ferrea, Enrico; Schachner, Melitta; Benfenati, Fabio; Giovedì, Silvia; Baldelli, Pietro

    2016-05-01

    L1 (also known as L1CAM) is a trans-membrane glycoprotein mediating neuron-neuron adhesion through homophilic and heterophilic interactions. Although experimental evidence has implicated L1 in axonal outgrowth, fasciculation and pathfinding, its contribution to voltage-gated Na(+) channel function and membrane excitability has remained unknown. Here, we show that firing rate, single cell spiking frequency and Na(+) current density are all reduced in hippocampal excitatory neurons from L1-deficient mice both in culture and in slices owing to an overall reduced membrane expression of Na(+) channels. Remarkably, normal firing activity was restored when L1 was reintroduced into L1-deficient excitatory neurons, indicating that abnormal firing patterns are not related to developmental abnormalities, but are a direct consequence of L1 deletion. Moreover, L1 deficiency leads to impairment of action potential initiation, most likely due to the loss of the interaction of L1 with ankyrin G that produces the delocalization of Na(+) channels at the axonal initial segment. We conclude that L1 contributes to functional expression and localization of Na(+) channels to the neuronal plasma membrane, ensuring correct initiation of action potential and normal firing activity. PMID:26985064

  18. Damage detection of metro tunnel structure through transmissibility function and cross correlation analysis using local excitation and measurement

    NASA Astrophysics Data System (ADS)

    Feng, Lei; Yi, Xiaohua; Zhu, Dapeng; Xie, Xiongyao; Wang, Yang

    2015-08-01

    In a modern metropolis, metro rail systems have become a dominant mode for mass transportation. The structural health of a metro tunnel is closely related to public safety. Many vibration-based techniques for detecting and locating structural damage have been developed in the past several decades. However, most damage detection techniques and validation tests are focused on bridge and building structures; very few studies have been reported on tunnel structures. Among these techniques, transmissibility function and cross correlation analysis are two well-known diagnostic approaches. The former operates in frequency domain and the latter in time domain. Both approaches can be applied to detect and locate damage through acceleration data obtained from sensor arrays. Furthermore, the two approaches can directly utilize structural response data without requiring excitation measurement, which offers advantages in field testing on a large structure. In this research, a numerical finite element model of a metro tunnel is built and different types of structural defects are introduced at multiple locations of the tunnel. Transmissibility function and cross correlation analysis are applied to perform structural damage detection and localization, based on simulated structural vibration data. Numerical results demonstrate that the introduced defects can be successfully identified and located. The sensitivity and feasibility of the two approaches have been verified when sufficient distribution of measurement locations is available. Damage detection results of the two different approaches are compared and discussed.

  19. Production of strange clusters in relativistic heavy ion collisions

    SciTech Connect

    Dover, C.B.; Baltz, A.J.; Pang, Yang; Schlagel, T.J.; Kahana, S.H.

    1993-02-01

    We address a number of issues related to the production of strangeness in high energy heavy ion collisions, including the possibility that stable states of multi-strange hyperonic or quark matter might exist, and the prospects that such objects may be created and detected in the laboratory. We make use of events generated by the cascade code ARC to estimate the rapidity distribution dN/dy of strange clusters produced in Si+Au and Au+Au collisions at AGS energies. These calculations are performed in a simple coalescence model, which yields a consistent description of the strange cluster (d, {sup 3}HE, {sup 3}H, {sup 4}He) production at these energies. If a doubly strange, weakly bound {Lambda}{Lambda} dibaryon exists, we find that it is produced rather copiously in Au+Au collisions, with dN/dy {approximately}0.1 at raid-rapidity. If one adds another non-strange or strange baryon to a cluster, the production rate decreases by roughly one or two orders of magnitude, respectively. For instance, we predict that the hypernucleus {sub {Lambda}{Lambda}}{sup 6}He should have dN/dy {approximately}5 {times} 10{sup {minus}6} for Au+Au central collisions. It should be possible to measure the successive {Lambda} {yields} p{pi}{minus} weak decays of this object. We comment on the possibility that conventional multi-strange hypernuclei may serve as ``doorway states`` for the production of stable configurations of strange quark matter, if such states exist.

  20. The Measurement of the Evaporation Residues Excitation Functions in the Fusion Reactions 144Sm (40Ar,xn) and 166Er(40Ar,xn)

    NASA Astrophysics Data System (ADS)

    Chernysheva, E. V.; Rodin, A. M.; Belozerov, A. V.; Dmitriev, S. N.; Gulyaev, A. V.; Gulyaeva, A. V.; Itkis, M. G.; Novoselov, A. S.; Oganessian, Yu. Ts.; Salamatin, V. S.; Stepantsov, S. V.; Vedeneev, V. Yu.; Yukhimchuk, S. A.; Krupa, L.; Kliman, J.; Motycak, S.; Sivacek, I.

    2015-06-01

    The evaporation residues excitation functions for the reactions 40Ar+144Sm→184Hg and 40Ar+166Er→206Rn were measured at the energies below and above the Coulomb barrier (Elab=142-207 MeV) using a mass-separator MASHA. The experimental data were compared with theoretical calculations using a Channel Coupling Model. The influence of experimental beam energy spread on the excitation functions was taking into account. It was found that structure of xn-cross sections correlate strongly with the nuclear structure of colliding nuclei.

  1. The Universe is a Strange Place

    NASA Astrophysics Data System (ADS)

    Wilczek, Frank

    2006-01-01

    Our understanding of ordinary matter is remarkably accurate and complete, but it is based on principles that are very strange and unfamiliar. As I'll explain, we've come to understand matter to be a Music of the Void, in a remarkably literal sense. Just as we physicists finalized that wonderful understanding, towards the end of the twentieth century, astronomers gave us back our humility, by informing us that ordinary matter - what we, and chemists and biologists, and astronomers themselves, have been studying all these centuries constitutes only about 5% of the mass of the universe as a whole. I'll describe some of our promising attempts to rise to this challenge by improving, rather than merely complicating, our description of the world.

  2. The Universe is a Strange Place

    NASA Astrophysics Data System (ADS)

    Wilczek, Frank

    Our understanding of ordinary matter is remarkably accurate and complete, but it is based on principles that are very strange and unfamiliar. As I'll explain, we've come to understand matter to be a Music of the Void, in a remarkably literal sense. Just as we physicists finalized that wonderful understanding, towards the end of the twentieth century, astronomers gave us back our humility, by informing us that ordinary matter - what we, and chemists and biologists, and astronomers themselves, have been studying all these centuries constitutes only about 5% of the mass of the universe as a whole. I'll describe some of our promising attempts to rise to this challenge by improving, rather than merely complicating, our description of the world.

  3. Role of nucleon strangeness in supernova explosions

    NASA Astrophysics Data System (ADS)

    Hobbs, T. J.; Alberg, Mary; Miller, Gerald A.

    2016-05-01

    Recent hydrodynamical simulations of core-collapse supernova (CCSN) evolution have highlighted the importance of thorough control over the microscopic physics responsible for such internal processes as neutrino heating. In particular, it has been suggested that modifications to the neutrino-nucleon elastic cross section can potentially play a crucial role in producing successful CCSN explosions. One possible source of such corrections can be found in a nonzero value for the nucleon's strange helicity content Δ s . In the present analysis, however, we show that theoretical and experimental progress over the past decade has suggested a comparatively small magnitude for Δ s , such that its sole effect is not sufficient to provide the physics leading to CCSN explosions.

  4. Multiresolution quantum chemistry in multiwavelet bases: excited states from time-dependent Hartree–Fock and density functional theory via linear response

    SciTech Connect

    Yanai, Takeshi; Fann, George I.; Beylkin, Gregory; Harrison, Robert J.

    2015-02-25

    Using the fully numerical method for time-dependent Hartree–Fock and density functional theory (TD-HF/DFT) with the Tamm–Dancoff (TD) approximation we use a multiresolution analysis (MRA) approach to present our findings. From a reformulation with effective use of the density matrix operator, we obtain a general form of the HF/DFT linear response equation in the first quantization formalism. It can be readily rewritten as an integral equation with the bound-state Helmholtz (BSH) kernel for the Green's function. The MRA implementation of the resultant equation permits excited state calculations without virtual orbitals. Moreover, the integral equation is efficiently and adaptively solved using a numerical multiresolution solver with multiwavelet bases. Our implementation of the TD-HF/DFT methods is applied for calculating the excitation energies of H2, Be, N2, H2O, and C2H4 molecules. The numerical errors of the calculated excitation energies converge in proportion to the residuals of the equation in the molecular orbitals and response functions. The energies of the excited states at a variety of length scales ranging from short-range valence excitations to long-range Rydberg-type ones are consistently accurate. It is shown that the multiresolution calculations yield the correct exponential asymptotic tails for the response functions, whereas those computed with Gaussian basis functions are too diffuse or decay too rapidly. Finally, we introduce a simple asymptotic correction to the local spin-density approximation (LSDA) so that in the TDDFT calculations, the excited states are correctly bound.

  5. Multiresolution quantum chemistry in multiwavelet bases: excited states from time-dependent Hartree–Fock and density functional theory via linear response

    DOE PAGESBeta

    Yanai, Takeshi; Fann, George I.; Beylkin, Gregory; Harrison, Robert J.

    2015-02-25

    Using the fully numerical method for time-dependent Hartree–Fock and density functional theory (TD-HF/DFT) with the Tamm–Dancoff (TD) approximation we use a multiresolution analysis (MRA) approach to present our findings. From a reformulation with effective use of the density matrix operator, we obtain a general form of the HF/DFT linear response equation in the first quantization formalism. It can be readily rewritten as an integral equation with the bound-state Helmholtz (BSH) kernel for the Green's function. The MRA implementation of the resultant equation permits excited state calculations without virtual orbitals. Moreover, the integral equation is efficiently and adaptively solved using amore » numerical multiresolution solver with multiwavelet bases. Our implementation of the TD-HF/DFT methods is applied for calculating the excitation energies of H2, Be, N2, H2O, and C2H4 molecules. The numerical errors of the calculated excitation energies converge in proportion to the residuals of the equation in the molecular orbitals and response functions. The energies of the excited states at a variety of length scales ranging from short-range valence excitations to long-range Rydberg-type ones are consistently accurate. It is shown that the multiresolution calculations yield the correct exponential asymptotic tails for the response functions, whereas those computed with Gaussian basis functions are too diffuse or decay too rapidly. Finally, we introduce a simple asymptotic correction to the local spin-density approximation (LSDA) so that in the TDDFT calculations, the excited states are correctly bound.« less

  6. Properties of color-flavor locked strange quark matter and strange stars in a new quark mass scaling

    NASA Astrophysics Data System (ADS)

    Chang, Qian; Chen, ShiWu; Peng, GuangXiong; Xu, JianFeng

    2013-09-01

    Considering the effect of one-gluon-exchange interaction between quarks, the color-flavor locked strange quark matter and strange stars are investigated in a new quark mass density-dependent model. It is found that the color-flavor locked strange quark matter can be more stable if the one-gluon-exchange effect is included. The lower density behavior of the sound velocity in this model is different from the previous results. Moreover, the new equation of state leads to a heavier acceptable maximum mass, supporting the recent observation of a compact star mass as large as about 2 times the solar mass.

  7. PREFACE: Strangeness in Quark Matter (SQM2009) Strangeness in Quark Matter (SQM2009)

    NASA Astrophysics Data System (ADS)

    Fraga, Eduardo; Kodama, Takeshi; Padula, Sandra; Takahashi, Jun

    2010-09-01

    The 14th International Conference on Strangeness in Quark Matter (SQM2009) was held in Brazil from 27 September to 2 October 2009 at Hotel Atlântico, Búzios, Rio de Janeiro. The conference was jointly organized by Universidade Federal do Rio de Janeiro, Universidade Estadual de Campinas, Centro Brasileiro de Pesquisas Físicas, Universidade de São Paulo, Universidade Estadual Paulista and Universidade Federal do Rio Grande do Sul. Over 120 scientists from Argentina, Brazil, China, France, Germany, Hungary, Italy, Japan, Mexico, The Netherlands, Norway, Poland, Russia, Slovakia, South Africa, Switzerland, the UK and the USA gathered at the meeting to discuss the physics of hot and dense matter through the signals of strangeness and also the behavior of heavy quarks. Group photograph The topics covered were strange and heavy quark production in nuclear collisions, strange and heavy quark production in elementary processes, bulk matter phenomena associated with strange and heavy quarks, and strangeness in astrophysics. In view of the LHC era and many other upcoming new machines, together with recent theoretical developments, sessions focused on `New developments and new facilities' and 'Open questions' were also included. A stimulating round-table discussion on 'Physics opportunities in the next decade in the view of strangeness and heavy flavor in matter' was chaired in a relaxed atmosphere by Grazyna Odyniec and conducted by P Braun-Munzinger, W Florkowski, K Redlich, K Šafařík and H Stöcker, We thank these colleagues for pointing out to young participants new physics directions to be pursued. We also thank J Dunlop and K Redlich for excellent introductory lectures given on the Sunday evening pre-conference session. In spite of the not-so-helpful weather, the beauty and charm of the town of Búzios helped to make the meeting successful. Nevertheless, the most important contributions were the excellent talks, whose contents are part of these proceedings, given

  8. Mass ejection by strange star mergers and observational implications.

    PubMed

    Bauswein, A; Janka, H-T; Oechslin, R; Pagliara, G; Sagert, I; Schaffner-Bielich, J; Hohle, M M; Neuhäuser, R

    2009-07-01

    We determine the Galactic production rate of strangelets as a canonical input to calculations of the measurable cosmic ray flux of strangelets by performing simulations of strange star mergers and combining the results with recent estimates of stellar binary populations. We find that the flux depends sensitively on the bag constant of the MIT bag model of QCD and disappears for high values of the bag constant and thus more compact strange stars. In the latter case, strange stars could coexist with ordinary neutron stars as they are not converted by the capture of cosmic ray strangelets. An unambiguous detection of an ordinary neutron star would then not rule out the strange matter hypothesis. PMID:19659133

  9. Exploring strange nucleon form factors on the lattice

    NASA Astrophysics Data System (ADS)

    Babich, Ronald; Brower, Richard C.; Clark, Michael A.; Fleming, George T.; Osborn, James C.; Rebbi, Claudio; Schaich, David

    2012-03-01

    We discuss techniques for evaluating sea quark contributions to hadronic form factors on the lattice and apply these to an exploratory calculation of the strange electromagnetic, axial, and scalar form factors of the nucleon. We employ the Wilson gauge and fermion actions on an anisotropic 243×64 lattice, probing a range of momentum transfer with Q2<1GeV2. The strange electric and magnetic form factors, GEs(Q2) and GMs(Q2), are found to be small and consistent with zero within the statistics of our calculation. The lattice data favor a small negative value for the strange axial form factor GAs(Q2) and exhibit a strong signal for the bare strange scalar matrix element ⟨N|s¯s|N⟩0. We discuss the unique systematic uncertainties affecting the latter quantity relative to the continuum, as well as prospects for improving future determinations with Wilson-like fermions.

  10. Mass Ejection by Strange Star Mergers and Observational Implications

    SciTech Connect

    Bauswein, A.; Janka, H.-T.; Oechslin, R.; Pagliara, G.; Schaffner-Bielich, J.; Sagert, I.; Hohle, M. M.; Neuhaeuser, R.

    2009-07-03

    We determine the Galactic production rate of strangelets as a canonical input to calculations of the measurable cosmic ray flux of strangelets by performing simulations of strange star mergers and combining the results with recent estimates of stellar binary populations. We find that the flux depends sensitively on the bag constant of the MIT bag model of QCD and disappears for high values of the bag constant and thus more compact strange stars. In the latter case, strange stars could coexist with ordinary neutron stars as they are not converted by the capture of cosmic ray strangelets. An unambiguous detection of an ordinary neutron star would then not rule out the strange matter hypothesis.

  11. K meson-nucleus interactions: strangeness and nuclear matter

    SciTech Connect

    Kahana, S.

    1985-01-01

    A brief review is provided of some straightforward K-nuclear and ..lambda..-hypernuclear systems. A discussion of less straightforward speculations on H-dibaryons and strange quark matter by many authors, is also given. 28 refs., 6 figs.

  12. EISCAT observations of pump-enhanced plasma temperature and optical emission excitation rate as a function of power flux

    NASA Astrophysics Data System (ADS)

    Bryers, C. J.; Kosch, M. J.; Senior, A.; Rietveld, M. T.; Yeoman, T. K.

    2012-09-01

    We analyze optical emissions and enhanced electron temperatures induced by high power HF radio waves as a function of power flux using the EISCAT heater with a range of effective radiated powers. The UHF radar was used to measure the electron temperatures and densities. The Digital All Sky Imager was used to record the 630.0 nm optical emission intensities. We quantify the HF flux loss due to self-absorption in the D-region (typically 3-11 dB) and refraction in the F-region to determine the flux which reaches the upper-hybrid resonance height. We find a quasi-linear relationship between the HF flux and both the temperature enhancement and the optical emission excitation rate with a threshold at ˜37.5 μWm-2. On average ˜70% of the HF flux at the upper-hybrid resonance height goes in to heating the electrons for fluxes above the threshold compared to ˜40% for fluxes below the threshold.

  13. Validation of Earth orientation parameters (EOP), geophysical excitation functions ( EF) and the second degree gravity field coefficients (GFC)

    NASA Astrophysics Data System (ADS)

    Heiker, A.; Schmidt, M.

    2012-04-01

    The project P9 of the research group "Earth rotation and geophysical processes" aims at the combined analysis and validation of Earth rotation observations and models (see Göttl et al. EGU 2012 poster). The EOP, EF and GFC are linked by the Earth tensor of inertia. This link is used for a sophisticated mutual validation. A least squares adjustment model which estimate the unknown tensor of inertia was developed for this purpose. Additionally variance and covariance components are estimated. The results of the adjustment model are the residuals for each data series and the adjusted tensor of inertia. It is assumed that the residuals contain the inconsistencies between the various time series. A thorough analysis of the residuals in the time and frequency domain reveals the systematic effects within the residuals. The adjusted variance and covariance components allow to check the standard deviations and in some cases the correlations given by the data centers. We present the results obtained from the combined analysis of IERS EOP, two different atmospheric and oceanic excitation functions (NCEP/ECCO from the Jet Propulsion Laboratory and ERAInterim/OMCT from the GeoForschungsZentrum (GFZ) Potsdam) and six different gravity field solutions (five GRACE solutions and one SLR solution).

  14. Electronic bands and excited states of III-V semiconductor polytypes with screened-exchange density functional calculations

    SciTech Connect

    Akiyama, Toru; Nakamura, Kohji; Ito, Tomonori; Freeman, Arthur J.

    2014-03-31

    The electronic band structures and excited states of III-V semiconductors such as GaP, AlP, AlAs, and AlSb for various polytypes are determined employing the screened-exchange density functional calculations implemented in the full-potential linearized augmented plane-wave methods. We demonstrate that GaP and AlSb in the wurtzite (WZ) structure have direct gap while III-V semiconductors in the zinc blende, 4H, and 6H structures considered in this study exhibit an indirect gap. Furthermore, we find that inclusion of Al atoms less than 17% and 83% in the hexagonal Al{sub x}Ga{sub 1−x}P and Al{sub x}Ga{sub 1−x}As alloys, respectively, leads to a direct transition with a gap energy of ∼2.3 eV. The feasibility of III-V semiconductors with a direct gap in WZ structure offers a possible crystal structure engineering to tune the optical properties of semiconductor materials.

  15. Electronic bands and excited states of III-V semiconductor polytypes with screened-exchange density functional calculations

    NASA Astrophysics Data System (ADS)

    Akiyama, Toru; Nakamura, Kohji; Ito, Tomonori; Freeman, Arthur J.

    2014-03-01

    The electronic band structures and excited states of III-V semiconductors such as GaP, AlP, AlAs, and AlSb for various polytypes are determined employing the screened-exchange density functional calculations implemented in the full-potential linearized augmented plane-wave methods. We demonstrate that GaP and AlSb in the wurtzite (WZ) structure have direct gap while III-V semiconductors in the zinc blende, 4H, and 6H structures considered in this study exhibit an indirect gap. Furthermore, we find that inclusion of Al atoms less than 17% and 83% in the hexagonal AlxGa1-xP and AlxGa1-xAs alloys, respectively, leads to a direct transition with a gap energy of ˜2.3 eV. The feasibility of III-V semiconductors with a direct gap in WZ structure offers a possible crystal structure engineering to tune the optical properties of semiconductor materials.

  16. Excitation functions of (d,x) nuclear reactions on natural titanium up to 24 MeV

    NASA Astrophysics Data System (ADS)

    Khandaker, Mayeen Uddin; Haba, Hiromitsu; Kanaya, Jumpei; Otuka, Naohiko

    2013-02-01

    Excitation functions of the natTi(d,x)48V and natTi(d,x)43,44m,44g,46,47,48Sc nuclear reactions were measured up to a 24-MeV deuteron energy by using a stacked-foil activation technique combined with γ-ray spectrometry with a high-purity germanium detector at the AVF cyclotron of the RIKEN RI Beam Factory, Wako, Japan. An overall good agreement is found between the measured cross-sections and the literature ones, whereas partial agreements are obtained for the theoretical calculations based on the TALYS code. Physical thick target yields, i.e., induced radioactivities per unit fluence of the 24-MeV deuteron were also deduced, and they were compared with the directly measured ones in the literature. The present results will have an important role in enrichment of the literature database of the deuteron-induced reactions on natural titanium leading to various applications.

  17. Higher dimensional strange quark matter solutions in self creation cosmology

    NASA Astrophysics Data System (ADS)

    Şen, R.; Aygün, S.

    2016-03-01

    In this study, we have generalized the higher dimensional flat Friedmann-Robertson-Walker (FRW) universe solutions for a cloud of string with perfect fluid attached strange quark matter (SQM) in Self Creation Cosmology (SCC). We have obtained that the cloud of string with perfect fluid does not survive and the string tension density vanishes for this model. However, we get dark energy model for strange quark matter with positive density and negative pressure in self creation cosmology.

  18. Hadron spectroscopy from strangeness to charm and beauty

    NASA Astrophysics Data System (ADS)

    Zou, B. S.

    2013-09-01

    Quarks of different flavors have different masses, which will cause breaking of flavor symmetries of QCD. Flavor symmetries and their breaking in hadron spectroscopy play important role for understanding the internal structures of hadrons. Hadron spectroscopy with strangeness reveals the importance of unquenched quark dynamics. Systematic study of hadron spectroscopy with strange, charm and beauty quarks would be very revealing and essential for understanding the internal structure of hadrons and its underlying quark dynamics.

  19. Overview of Issues Surrounding Strangeness in the Nucleon

    SciTech Connect

    A. W. Thomas

    2009-12-01

    The calculation of the strangeness content of the nucleon and its experimental verification is a fundamental step in establishing non-perturbative QCD as the correct theory describing the structure of hadrons. It holds a role in QCD analogous to the correct calculation of the Lamb shift in QED. We review the latest developments in the vector and scalar matrix elements of the strange quarks in the proton, where there has recently been considerable progress.

  20. Nucleation of strange matter in dense stellar cores

    SciTech Connect

    Horvath, J.E. Sao Paulo, Sao Paulo ); Benvenuto, O.G. La Plata ); Vucetich, H. La Plata )

    1992-05-15

    We investigate the nucleation of strange quark matter inside hot, dense nuclear matter. Applying Zel'dovich's kinetic theory of nucleation we find a lower limit of the temperature {ital T} for strange-matter bubbles to appear, which happens to be satisfied inside the Kelvin-Helmholtz cooling era of a compact star life but not much after it. Our bounds thus suggest that a prompt conversion could be achieved, giving support to earlier expectations for nonstandard type-II supernova scenarios.

  1. GENERAL: Non-Spherical Gravitational Collapse of Strange Quark Matter

    NASA Astrophysics Data System (ADS)

    S, Zade S.; D, Patil K.; N, Mulkalwar P.

    2008-05-01

    We study the non-spherical gravitational collapse of the strange quark null fluid. The interesting feature which emerges is that the non-spherical collapse of charged strange quark matter leads to a naked singularity whereas the gravitational collapse of neutral quark matter proceeds to form a black hole. We extend the earlier work of Harko and Cheng [Phys. Lett. A 266 (2000) 249] to the non-spherical case.

  2. New evolution equations for the joint response-excitation probability density function of stochastic solutions to first-order nonlinear PDEs

    SciTech Connect

    Venturi, D.; Karniadakis, G.E.

    2012-08-30

    By using functional integral methods we determine new evolution equations satisfied by the joint response-excitation probability density function (PDF) associated with the stochastic solution to first-order nonlinear partial differential equations (PDEs). The theory is presented for both fully nonlinear and for quasilinear scalar PDEs subject to random boundary conditions, random initial conditions or random forcing terms. Particular applications are discussed for the classical linear and nonlinear advection equations and for the advection-reaction equation. By using a Fourier-Galerkin spectral method we obtain numerical solutions of the proposed response-excitation PDF equations. These numerical solutions are compared against those obtained by using more conventional statistical approaches such as probabilistic collocation and multi-element probabilistic collocation methods. It is found that the response-excitation approach yields accurate predictions of the statistical properties of the system. In addition, it allows to directly ascertain the tails of probabilistic distributions, thus facilitating the assessment of rare events and associated risks. The computational cost of the response-excitation method is order magnitudes smaller than the one of more conventional statistical approaches if the PDE is subject to high-dimensional random boundary or initial conditions. The question of high-dimensionality for evolution equations involving multidimensional joint response-excitation PDFs is also addressed.

  3. Benchmarking DFT and TD-DFT Functionals for the Ground and Excited States of Hydrogen-Rich Peptide Radicals.

    PubMed

    Riffet, Vanessa; Jacquemin, Denis; Cauët, Emilie; Frison, Gilles

    2014-08-12

    We assess the pros and cons of a large panel of DFT exchange-correlation functionals for the prediction of the electronic structure of hydrogen-rich peptide radicals formed after electron attachment on a protonated peptide. Indeed, despite its importance in the understanding of the chemical changes associated with the reduction step, the question of the attachment site of an electron and, more generally, of the reduced species formed in the gas phase through electron-induced dissociation (ExD) processes in mass spectrometry is still a matter of debate. For hydrogen-rich peptide radicals in which several positive groups and low-lying π* orbitals can capture the incoming electron in ExD, inclusion of full Hartree-Fock exchange at long-range interelectronic distance is a prerequisite for an accurate description of the electronic states, thereby excluding several popular exchange-correlation functionals, e.g., B3LYP, M06-2X, or CAM-B3LYP. However, we show that this condition is not sufficient by comparing the results obtained with asymptotically correct range-separated hybrids (M11, LC-BLYP, LC-BPW91, ωB97, ωB97X, and ωB97X-D) and with reference CASSCF-MRCI and EOM-CCSD calculations. The attenuation parameter ω significantly tunes the spin density distribution and the excited states vertical energies. The investigated model structures, ranging from methylammonium to hexapeptide, allow us to obtain a description of the nature and energy of the electronic states, depending on (i) the presence of hydrogen bond(s) around the cationic site(s), (ii) the presence of π* molecular orbitals (MOs), and (iii) the selected DFT approach. It turns out that, in the present framework, LC-BLYP and ωB97 yields the most accurate results. PMID:26588300

  4. A comprehensive study of sensorimotor cortex excitability in chronic cocaine users: Integrating TMS and functional MRI data☆

    PubMed Central

    Hanlon, Colleen A.; DeVries, William; Dowdle, Logan T.; West, Julia A.; Siekman, Bradley; Li, Xingbao; George, Mark S.

    2016-01-01

    Background Disruptions in motor control are often overlooked features of chronic cocaine users. During a simple sensorimotor integration task, for example, cocaine users activate a larger area of cortex than controls but have lower functional connectivity between the cortex and dorsal striatum, which is further correlated with poor performance. The purpose of this study was to determine whether abnormal cortical excitability in cocaine users was related to disrupted inhibitory or excitatory mechanisms, as measured by transcranial magnetic stimulation (TMS). Methods A battery of TMS measures were acquired from 87 individuals (50 cocaine dependent, 37 controls). Functional MRI data were acquired from a subset of 28 individuals who performed a block-design finger tapping task. Results TMS measures revealed that cocaine users had significantly higher resting motor thresholds and higher intracortical cortical facilitation (ICF) than controls. There was no between-group difference in either measure of cortical inhibition. Task-evoked BOLD signal in the motor cortex was significantly correlated with ICF in the cocaine users. There was no significant difference in brain-skull distance between groups. Conclusion These data demonstrated that cocaine users have disrupted cortical facilitation (as measured with TMS), which is related to elevated BOLD signal. Cortical inhibition, however, is largely intact. Given the relationship between ICF and glutamatergic agents, this may be a potentially fruitful and treatable target in addiction. Finally, among controls the distance from the scalp to the cortex was correlated with the motor threshold which may be a useful parameter to integrate into therapeutic TMS protocols in the future. PMID:26541870

  5. Moments of inertia for neutron and strange stars: Limits derived for the Crab pulsar

    NASA Astrophysics Data System (ADS)

    Bejger, M.; Haensel, P.

    2002-12-01

    Recent estimates of the properties of the Crab nebula are used to derive constraints on the moment of inertia, mass and radius of the pulsar. To this purpose, we employ an approximate formula combining these three parameters. Our ``empirical formula'' I =~ a(x) M R2, where x=(M/Msun) (km/R), is based on numerical results obtained for thirty theoretical equations of state of dense matter. The functions a(x) for neutron stars and strange stars are qualitatively different. For neutron stars aNS(x)=x/(0.1+2x) for x<=0.1 (valid for M>0.2 Msun) and aNS(x)={2/ 9}(1+5x) for x>0.1. For strange stars aSS(x)={2/ 5}(1+x) (not valid for strange stars with crust and M<0.1 Msun). We obtain also an approximate expression for the maximum moment of inertia Imax,45 =~ (-0.37 + 7.12* xmax) (Mmax/Msun)(RM_max/ {10 km})2, where I45 = I/1045 g* cm2, valid for both neutron stars and strange stars. Applying our formulae to the evaluated values of ICrab, we derive constraints on the mass and radius of the pulsar. { A very conservative evaluation of the expanding nebula mass, Mneb=2 Msun, yields MCrab>1.2 Msun and RCrab= 10-14 km. Setting the most recent evaluation (``central value'') Mneb=4.6 Msun rules out most of the existing equations of state, leaving only the stiffest ones: MCrab>1.9 Msun, RCrab= 14-15 km.

  6. Assessment of charge-transfer excitations with time-dependent, range-separated density functional theory based on long-range MP2 and multiconfigurational self-consistent field wave functions

    NASA Astrophysics Data System (ADS)

    Hedegârd, Erik Donovan; Heiden, Frank; Knecht, Stefan; Fromager, Emmanuel; Jensen, Hans Jørgen Aagaard

    2013-11-01

    Charge transfer excitations can be described within Time-Dependent Density Functional Theory (TD-DFT), not only by means of the Coulomb Attenuated Method (CAM) but also with a combination of wave function theory and TD-DFT based on range separation. The latter approach enables a rigorous formulation of multi-determinantal TD-DFT schemes where excitation classes, which are absent in conventional TD-DFT spectra (like for example double excitations), can be addressed. This paper investigates the combination of both the long-range Multi-Configuration Self-Consistent Field (MCSCF) and Second Order Polarization Propagator Approximation (SOPPA) ansätze with a short-range DFT (srDFT) description. We find that the combinations of SOPPA or MCSCF with TD-DFT yield better results than could be expected from the pure wave function schemes. For the Time-Dependent MCSCF short-range DFT ansatz (TD-MC-srDFT) excitation energies calculated over a larger benchmark set of molecules with predominantly single reference character yield good agreement with their reference values, and are in general comparable to the CAM-B3LYP functional. The SOPPA-srDFT scheme is tested for a subset of molecules used for benchmarking TD-MC-srDFT and performs slightly better against the reference data for this small subset. Beyond the proof-of-principle calculations comprising the first part of this contribution, we additionally studied the low-lying singlet excited states (S1 and S2) of the retinal chromophore. The chromophore displays multireference character in the ground state and both excited states exhibit considerable double excitation character, which in turn cannot be described within standard TD-DFT, due to the adiabatic approximation. However, a TD-MC-srDFT approach can account for the multireference character, and excitation energies are obtained with accuracy comparable to CASPT2, although using a much smaller active space.

  7. Assessment of charge-transfer excitations with time-dependent, range-separated density functional theory based on long-range MP2 and multiconfigurational self-consistent field wave functions.

    PubMed

    Hedegård, Erik Donovan; Heiden, Frank; Knecht, Stefan; Fromager, Emmanuel; Jensen, Hans Jørgen Aagaard

    2013-11-14

    Charge transfer excitations can be described within Time-Dependent Density Functional Theory (TD-DFT), not only by means of the Coulomb Attenuated Method (CAM) but also with a combination of wave function theory and TD-DFT based on range separation. The latter approach enables a rigorous formulation of multi-determinantal TD-DFT schemes where excitation classes, which are absent in conventional TD-DFT spectra (like for example double excitations), can be addressed. This paper investigates the combination of both the long-range Multi-Configuration Self-Consistent Field (MCSCF) and Second Order Polarization Propagator Approximation (SOPPA) ansätze with a short-range DFT (srDFT) description. We find that the combinations of SOPPA or MCSCF with TD-DFT yield better results than could be expected from the pure wave function schemes. For the Time-Dependent MCSCF short-range DFT ansatz (TD-MC-srDFT) excitation energies calculated over a larger benchmark set of molecules with predominantly single reference character yield good agreement with their reference values, and are in general comparable to the CAM-B3LYP functional. The SOPPA-srDFT scheme is tested for a subset of molecules used for benchmarking TD-MC-srDFT and performs slightly better against the reference data for this small subset. Beyond the proof-of-principle calculations comprising the first part of this contribution, we additionally studied the low-lying singlet excited states (S1 and S2) of the retinal chromophore. The chromophore displays multireference character in the ground state and both excited states exhibit considerable double excitation character, which in turn cannot be described within standard TD-DFT, due to the adiabatic approximation. However, a TD-MC-srDFT approach can account for the multireference character, and excitation energies are obtained with accuracy comparable to CASPT2, although using a much smaller active space. PMID:24320275

  8. Excited meson radiative transitions from lattice QCD using variationally optimized operators

    SciTech Connect

    Shultz, Christian J.; Dudek, Jozef J.; Edwards, Robert G.

    2015-06-02

    We explore the use of 'optimized' operators, designed to interpolate only a single meson eigenstate, in three-point correlation functions with a vector-current insertion. These operators are constructed as linear combinations in a large basis of meson interpolating fields using a variational analysis of matrices of two-point correlation functions. After performing such a determination at both zero and non-zero momentum, we compute three-point functions and are able to study radiative transition matrix elements featuring excited state mesons. The required two- and three-point correlation functions are efficiently computed using the distillation framework in which there is a factorization between quark propagation and operator construction, allowing for a large number of meson operators of definite momentum to be considered. We illustrate the method with a calculation using anisotopic lattices having three flavors of dynamical quark all tuned to the physical strange quark mass, considering form-factors and transitions of pseudoscalar and vector meson excitations. In conclusion, the dependence on photon virtuality for a number of form-factors and transitions is extracted and some discussion of excited-state phenomenology is presented.

  9. Cryogenic exciter

    SciTech Connect

    Bray, James William; Garces, Luis Jose

    2012-03-13

    The disclosed technology is a cryogenic static exciter. The cryogenic static exciter is connected to a synchronous electric machine that has a field winding. The synchronous electric machine is cooled via a refrigerator or cryogen like liquid nitrogen. The static exciter is in communication with the field winding and is operating at ambient temperature. The static exciter receives cooling from a refrigerator or cryogen source, which may also service the synchronous machine, to selected areas of the static exciter and the cooling selectively reduces the operating temperature of the selected areas of the static exciter.

  10. Derivation of the RPA (Random Phase Approximation) Equation of ATDDFT (Adiabatic Time Dependent Density Functional Ground State Response Theory) from an Excited State Variational Approach Based on the Ground State Functional.

    PubMed

    Ziegler, Tom; Krykunov, Mykhaylo; Autschbach, Jochen

    2014-09-01

    The random phase approximation (RPA) equation of adiabatic time dependent density functional ground state response theory (ATDDFT) has been used extensively in studies of excited states. It extracts information about excited states from frequency dependent ground state response properties and avoids, thus, in an elegant way, direct Kohn-Sham calculations on excited states in accordance with the status of DFT as a ground state theory. Thus, excitation energies can be found as resonance poles of frequency dependent ground state polarizability from the eigenvalues of the RPA equation. ATDDFT is approximate in that it makes use of a frequency independent energy kernel derived from the ground state functional. It is shown in this study that one can derive the RPA equation of ATDDFT from a purely variational approach in which stationary states above the ground state are located using our constricted variational DFT (CV-DFT) method and the ground state functional. Thus, locating stationary states above the ground state due to one-electron excitations with a ground state functional is completely equivalent to solving the RPA equation of TDDFT employing the same functional. The present study is an extension of a previous work in which we demonstrated the equivalence between ATDDFT and CV-DFT within the Tamm-Dancoff approximation. PMID:26588541

  11. Sexual excitement.

    PubMed

    Stoller, R J

    1976-08-01

    Sexual excitement depends on a scenario the person to be aroused has been writing since childhood. The story is an adventure, an autobiography disguised as fiction, in which the hero/heroine hides crucial intrapsychic conflicts, mysteries, screen memories of actual traumatic events and the resolution of these elements into a happy ending, best celebrated by orgasm. The function of the fantasy is to take these painful experiences and convert them to pleasure-triumph. In order to sharpen excitement-the vibration between the fear of original traumas repeating and the hope of a pleasurable conclusion this time-one introduces into the story elements of risk (approximations of the trauma) meant to prevent boredom and safety factors (sub-limnal signals to the storyteller that the risk are not truly dangerous). Sexual fantasy can be studied by means of a person's daydreams (including those chosen in magazines, books, plays, television, movies, and outright pornography), masturbatory behavior, object choice, foreplay, techniques of intercourse, or postcoital behavior. PMID:949223

  12. Spin-dependent localized Hartree-Fock density-functional calculation of singly, doubly, and triply excited and Rydberg states of He- and Li-like ions

    SciTech Connect

    Zhou Zhongyuan; Chu, Shih-I

    2005-02-01

    A spin-dependent density-functional approach for the calculation of highly and multiply excited state of atomic system is proposed based on the localized Hartree-Fock density-functional method and Slater's diagonal sum rule. In this approach, electron spin orbitals in an electronic configuration are obtained first by solving the Kohn-Sham equation with an exact nonvariational spin-dependent localized Hartree-Fock exchange potential. Then a single-Slater-determinant energy of the electronic configuration is calculated by using these electron spin orbitals. Finally, a multiplet energy of an excited state is evaluated from the single-Slater-determinant energies of the electronic configurations involved in terms of Slater's diagonal sum rule. This approach has been applied to the calculation of singly, doubly, and especially triply excited Rydberg states of He- and Li-like ions. The total energies obtained from the calculation with an exchange-only (X-only) potential are surprisingly close to those of Hartree-Fock method and the total energies from the calculation with exchange-correlation potential are in overall agreement with available theoretical and experimental data. The presented procedure provides a simple and computationally efficient scheme for the accurate calculation of highly and multiply excited Rydberg states of an atomic system within density-functional theory.

  13. Atomic, Molecular, and Optical Physics: Optical Excitation Function of H(1s-2p) Produced by electron Impact from Threshold to 1.8 keV

    NASA Technical Reports Server (NTRS)

    James, G. K.; Slevin, J. A.; Shemansky, D. E.; McConkey, J. W.; Bray, I.; Dziczek, D.; Kanik, I.; Ajello, J. M.

    1997-01-01

    The optical excitation function of prompt Lyman-Alpha radiation, produced by electron impact on atomic hydrogen, has been measured over the extended energy range from threshold to 1.8 keV. Measurements were obtained in a crossed-beams experiment using both magnetically confined and electrostatically focused electrons in collision with atomic hydrogen produced by an intense discharge source. A vacuum-ultraviolet mono- chromator system was used to measure the emitted Lyman-Alpha radiation. The absolute H(1s-2p) electron impact excitation cross section was obtained from the experimental optical excitation function by normalizing to the accepted optical oscillator strength, with corrections for polarization and cascade. Statistical and known systematic uncertainties in our data range from +/- 4% near threshold to +/- 2% at 1.8 keV. Multistate coupling affecting the shape of the excitation function up to 1 keV impact energy is apparent in both the present experimental data and present theoretical results obtained with convergent close- coupling (CCC) theory. This shape function effect leads to an uncertainty in absolute cross sections at the 10% level in the analysis of the experimental data. The derived optimized absolute cross sections are within 7% of the CCC calculations over the 14 eV-1.8 keV range. The present CCC calculations converge on the Bethe- Fano profile for H(1s-2p) excitation at high energy. For this reason agreement with the CCC values to within 3% is achieved in a nonoptimal normalization of the experimental data to the Bethe-Fano profile. The fundamental H(1s-2p) electron impact cross section is thereby determined to an unprecedented accuracy over the 14 eV - 1.8 keV energy range.

  14. Analytical second derivatives of excited-state energy within the time-dependent density functional theory coupled with a conductor-like polarizable continuum model

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Liang, WanZhen

    2013-01-01

    This work extends our previous works [J. Liu and W. Z. Liang, J. Chem. Phys. 135, 014113 (2011), 10.1063/1.3605504; J. Liu and W. Z. Liang, J. Chem. Phys. 135, 184111 (2011)], 10.1063/1.3659312 on analytical excited-state Hessian within the framework of time-dependent density functional theory (TDDFT) to couple with a conductor-like polarizable continuum model (CPCM). The formalism, implementation, and application of analytical first and second energy derivatives of TDDFT/CPCM excited state with respect to the nuclear and electric perturbations are presented. Their performances are demonstrated by the calculations of excitation energies, excited-state geometries, and harmonic vibrational frequencies for a number of benchmark systems. The calculated results are in good agreement with the corresponding experimental data or other theoretical calculations, indicating the reliability of the current computer implementation of the developed algorithms. Then we made some preliminary applications to calculate the resonant Raman spectrum of 4-hydroxybenzylidene-2,3-dimethyl-imidazolinone in ethanol solution and the infrared spectra of ground and excited states of 9-fluorenone in methanol solution.

  15. Role of resonance-enhanced multiphoton excitation in high-harmonic generation of N2: A time-dependent density-functional-theory study

    NASA Astrophysics Data System (ADS)

    Chu, Xi; Groenenboom, Gerrit C.

    2013-01-01

    A minimum at ˜39 eV is observed in the high-harmonic-generation spectra of N2 for several laser intensities and frequencies. This minimum appears to be invariant for different molecular orientations. We reproduce this minimum for a set of laser parameters and orientations in time-dependent density-functional-theory calculations, which also render orientation-dependent maxima at 23-26 eV. Photon energies of these maxima overlap with ionization potentials of excited states observed in photoelectron spectra. Time profile analysis shows that these maxima are caused by resonance-enhanced multiphoton excitation. We propose a four-step mechanism, in which an additional excitation step is added to the well-accepted three-step model. Excitation to a linear combination of Rydberg states c4'1Σu+ and c31Πu gives rise to an orientation-invariant minimum analogous to the “Cooper minimum” in argon. When the molecular axis is parallel to the polarization direction of the field, a radial node goes through the atomic centers, and hence the Cooper-like minimum coincides with the minimum predicted by a modified two-center interference model that considers the de-excitation of the ion and symmetry of the Rydberg orbital.

  16. Synthesis and functionalization of monodisperse near-ultraviolet and visible excitable multifunctional Eu(3+), Bi(3+):REVO4 nanophosphors for bioimaging and biosensing applications.

    PubMed

    Escudero, Alberto; Carrillo-Carrión, Carolina; Zyuzin, Mikhail V; Ashraf, Sumaira; Hartmann, Raimo; Núñez, Nuria O; Ocaña, Manuel; Parak, Wolfgang J

    2016-06-16

    Near-ultraviolet and visible excitable Eu- and Bi-doped NPs based on rare earth vanadates (REVO4, RE = Y, Gd) have been synthesized by a facile route from appropriate RE precursors, europium and bismuth nitrate, and sodium orthovanadate, by homogeneous precipitation in an ethylene glycol/water mixture at 120 °C. The NPs can be functionalized either by a one-pot synthesis with polyacrylic acid (PAA) or by a Layer-by-Layer approach with poly(allylamine hydrochloride) (PAH) and PAA. In the first case, the particle size can also be tuned by adjusting the amount of PAA. The Eu- Bi-doped REVO4 based nanophosphors show the typical red luminescence of Eu(iii), which can be excited through an energy transfer process from the vanadate anions, resulting in a much higher luminescence intensity in comparison to the direct excitation of the europium cations. The incorporation of Bi into the REVO4 structure shifts the original absorption band of the vanadate anions towards longer wavelengths, giving rise to nanophosphors with an excitation maximum at 342 nm, which can also be excited in the visible range. The suitability of such nanophosphors for bioimaging and biosensing applications, as well as their colloidal stability in different buffer media of biological interest, their cytotoxicity, their degradability at low pH, and their uptake by HeLa cells have been evaluated. Their suitability for bioimaging and biosensing applications is also demonstrated. PMID:27253384

  17. Tight-binding approximations to time-dependent density functional theory - A fast approach for the calculation of electronically excited states.

    PubMed

    Rüger, Robert; van Lenthe, Erik; Heine, Thomas; Visscher, Lucas

    2016-05-14

    We propose a new method of calculating electronically excited states that combines a density functional theory based ground state calculation with a linear response treatment that employs approximations used in the time-dependent density functional based tight binding (TD-DFTB) approach. The new method termed time-dependent density functional theory TD-DFT+TB does not rely on the DFTB parametrization and is therefore applicable to systems involving all combinations of elements. We show that the new method yields UV/Vis absorption spectra that are in excellent agreement with computationally much more expensive TD-DFT calculations. Errors in vertical excitation energies are reduced by a factor of two compared to TD-DFTB. PMID:27179467

  18. Tight-binding approximations to time-dependent density functional theory — A fast approach for the calculation of electronically excited states

    NASA Astrophysics Data System (ADS)

    Rüger, Robert; van Lenthe, Erik; Heine, Thomas; Visscher, Lucas

    2016-05-01

    We propose a new method of calculating electronically excited states that combines a density functional theory based ground state calculation with a linear response treatment that employs approximations used in the time-dependent density functional based tight binding (TD-DFTB) approach. The new method termed time-dependent density functional theory TD-DFT+TB does not rely on the DFTB parametrization and is therefore applicable to systems involving all combinations of elements. We show that the new method yields UV/Vis absorption spectra that are in excellent agreement with computationally much more expensive TD-DFT calculations. Errors in vertical excitation energies are reduced by a factor of two compared to TD-DFTB.

  19. Atmospheric neutrinos can make beauty strange

    SciTech Connect

    Harnik, Roni; Larson, Daniel T.; Murayama, Hitoshi; Pierce, Aaron

    2002-12-01

    The large observed mixing angle in atmospheric neutrinos, coupled with Grand Unification, motivates the search for a large mixing between right-handed strange and bottom squarks. Such mixing does not appear in the standard CKM phenomenology, but may induce significant b {yields} s transitions through gluino diagrams. Working in the mass eigenbasis, we show quantitatively that an order one effect on CP violation in B{sub d}{sup 0} {yields} {pi}K{sub S} is possible due to a large mixing between right-handed b and s squarks, while still satisfying constraints from b {yields} s {gamma}. We also include the effect of right- and left-handed bottom squark mixing proportional to m{sub b}{mu} tan{beta}. For small {mu}tan{beta} there may also be a large effect in B{sub s} mixing correlated with a large effect in B{sub d}{sup 0} {yields} {phi}K{sub S}, typically yielding an unambiguous signal of new physics at Tevatron Run II.

  20. Strangeness Prospects with the CBM Experiment

    NASA Astrophysics Data System (ADS)

    Friese, Volker

    2016-01-01

    The CBM experiment will study strongly interacting matter at high net-baryon densities with nuclear collisions up to 45A GeV beam energy at the future FAIR facility. With interaction rates unprecedented in heavy-ion collisions, CBM will give access also to extremely rare probes and thus to the early stage of the collisions, in search for the first-order phase transition from confined to deconfined matter and the QCD critical point. The CBM physics programme will be started with beams delivered by the SIS-100 synchrotron, providing energies from 2 to 11 GeV/nucleon for heavy nuclei, up to 14 GeV/nucleon for light nuclei, and 30 GeV for protons. The highest net baryon densities will be explored with ion beams up to 45 GeV/nucleon energy delivered by SIS-300 in a later stage of the FAIR project. After several years of preparation, the CBM experiment now enters the realisation phase. In this article, we report on the current status of the system developments and the expected physics performance for strange and charmed observables, as well as on the roadmap towards the first data taking.

  1. Optical Measurements of Thermal Diffusivity in Strange Metals

    NASA Astrophysics Data System (ADS)

    Zhang, Jiecheng; Levenson-Falk, E. M.; Kapitulnik, Aharon

    Thermal transport measurements of strongly correlated electronic systems provide key insight into their emerging collective behavior. For example, high-Tc superconductors exhibit different regimes of unusual transport with ``bad metallicity'' at high temperatures, a pseudogap-dominated transport at intermediate temperatures, and the interplay with superconductivity at low temperatures. We present optical non-contact measurements of local thermal diffusivity in such materials. In our apparatus we focus a laser spot onto the surface of the investigated sample; the laser power is then modulated to create a periodic, point-like heat source. Another laser is focused nearby on the surface where the local reflectivity is measured. Since the reflectivity is temperature-dependent, it serves as a contactless probe of temperature oscillations due to the heat source. By measuring the temperature profile on the surface of the sample as a function of modulation frequency, we extract the thermal diffusivity of the material. We will present measurements of the temperature dependence and anisotropy of diffusivity in various strange metals, and discuss further applications of the apparatus.

  2. Ab Initio Geometry and Bright Excitation of Carotenoids: Quantum Monte Carlo and Many Body Green’s Function Theory Calculations on Peridinin

    PubMed Central

    Coccia, Emanuele; Varsano, Daniele; Guidoni, Leonardo

    2016-01-01

    In this letter, we report the singlet ground state structure of the full carotenoid peridinin by means of variational Monte Carlo (VMC) calculations. The VMC relaxed geometry has an average bond length alternation of 0.1165(10) Å, larger than the values obtained by DFT (PBE, B3LYP, and CAM-B3LYP) and shorter than that calculated at the Hartree–Fock (HF) level. TDDFT and EOM-CCSD calculations on a reduced peridinin model confirm the HOMO–LUMO major contribution of the Bu+-like (S2) bright excited state. Many Body Green’s Function Theory (MBGFT) calculations of the vertical excitation energy of the Bu+-like state for the VMC structure (VMC/MBGFT) provide an excitation energy of 2.62 eV, in agreement with experimental results in n-hexane (2.72 eV). The dependence of the excitation energy on the bond length alternation in the MBGFT and TDDFT calculations with different functionals is discussed. PMID:26580027

  3. Numerical simulation of the transient photoconductivity in a-Si:H as a function of excitation density

    SciTech Connect

    Feist, H.; Kunst, M.

    1997-07-01

    The dependence of the transient photoconductivity induced by pulsed excitation (TPC) on the excitation density is discussed with the help of numerical simulations. It is shown that recombination between excess mobile electrons and all excess holes (mainly localized) can explain the excitation density dependence of the TPC amplitude of standard a-Si:H at room temperature using a rate parameter k{sub BB} of 10{sup {minus}8} cm{sup 3}/s. This model leads to a decay faster than experimentally observed in the time range from 40 ns to 1 {micro}s. A variation of the recombination model is presented that gives short time range. Moreover comparison of the simulations with experimental data yields limits for the parameters of the conduction band tail. In particular, the time necessary to establish a dynamic equilibrium of excess electrons between delocalized states in the conduction band and localized states in the tail appears to be very informative.

  4. Density functional study of multiplicity-changing valence and Rydberg excitations of p-block elements: delta self-consistent field, collinear spin-flip time-dependent density functional theory (DFT), and conventional time-dependent DFT.

    PubMed

    Yang, Ke; Peverati, Roberto; Truhlar, Donald G; Valero, Rosendo

    2011-07-28

    A database containing 17 multiplicity-changing valence and Rydberg excitation energies of p-block elements is used to test the performance of density functional theory (DFT) with approximate density functionals for calculating relative energies of spin states. We consider only systems where both the low-spin and high-spin state are well described by a single Slater determinant, thereby avoiding complications due to broken-symmetry solutions. Because the excitations studied involve a spin change, they require a balanced treatment of exchange and correlation, thus providing a hard test for approximate density functionals. We test three formalisms for predicting the multiplicity-changing transition energies. First is the ΔSCF method; we also test time-dependent density functional theory (TDDFT), both in its conventional form starting from the low-spin state and in its collinear spin-flip form starting from the high-spin state. Very diffuse basis functions are needed to give a qualitatively correct description of the Rydberg excitations. The scalar relativistic effect needs to be considered when quantitative results are desired, and we include it in the comparisons. With the ΔSCF method, most of the tested functionals give mean unsigned errors (MUEs) larger than 6 kcal/mol for valence excitations and MUEs larger than 3 kcal/mol for Rydberg excitations, but the performance for the Rydberg states is much better than can be obtained with time-dependent DFT. It is surprising to see that the long-range corrected functionals, which have 100% Hartree-Fock exchange at large inter-electronic distance, do not improve the performance for Rydberg excitations. Among all tested density functionals, ΔSCF calculations with the O3LYP, M08-HX, and OLYP functionals give the best overall performance for both valence and Rydberg excitations, with MUEs of 2.1, 2.6, and 2.7 kcal/mol, respectively. This is very encouraging since the MUE of the CCSD(T) coupled cluster method with quintuple

  5. Effect of Peruvosid (CD412) on excitability and functional refractory period of atrial and ventricular tissues in cardiomyopathy caused by Trypanosoma cruzi

    PubMed Central

    Moleiro, Frederico; Anselmi, Alfonso; Suárez, Régulo; Suárez, José Angel; Drayer, Alberto

    1970-01-01

    Attempts were made to produce myocarditis by Trypanosoma cruzi inoculation in healthy dog puppies 6 to 8 weeks old. Significant electrocardiographic abnormalities were produced, coinciding with interstitial inflammatory processes in the cardiac tissue and with degenerative changes in the myocardial fibres. In puppies showing these changes, profound changes in the excitability and the functional refractory period of the atrial and ventricular muscular tissue were observed. The administration of Peruvosid in doses of 0·0240 to 0·0647 mg./kg. tended to diminish the excitability, previously increased by the inflammatory process, at the same time increasing the functional refractory period duration which had previously been shortened. The fact that Peruvosid corrects these fundamental factors in the genesis of cardiac arrhythmias suggests that the drug may be useful in the treatment of cardiac insufficiency produced by Chagas' myocardiopathy, in which arrhythmias are one of the basic characteristics. Images PMID:4985863

  6. Nickel-63 production in copper samples exposed to the Hiroshima atomic bomb: estimation based on an excitation function obtained by neutron irradiation experiments.

    PubMed

    Takamiya, K; Imanaka, T; Ota, Y; Akamine, M; Shibata, S; Shibata, T; Ito, Y; Imamura, M; Uwamino, Y; Nogawa, N; Baba, M; Iwasaki, S; Matsuyama, S

    2008-07-01

    The upper and lower limits of the excitation function of the (63)Cu(n,p)(63)Ni reaction were experimentally determined, and the number of (63)Ni nuclei produced in copper samples exposed to atomic bomb neutrons in Hiroshima was estimated by using the experimental excitation functions and the neutron fluences given in the DS02 dosimetry system. The estimated number of (63)Ni nuclei was compared with that measured and with that calculated using the DS02 dosimetry system and the corresponding ENDF/B-VI cross section. In comparison with DS02, there is about a 60% maximum difference in (63)Ni production at the hypocenter when the experimental upper cross section values are used. The difference becomes smaller at greater distances from the hypocenter and decreases, for example, to less than 30 and 5% when using the upper and lower experimental cross sections at 1,000 m, respectively. PMID:18496703

  7. Measurement of excitation functions in the reactions 197Au(11C, xn)208-xAt using a radioactive 11C beam

    PubMed

    Joosten; Powell; Guo; Haustein; Larimer; McMahan; Norman; O'Neil; Rowe; VanBrocklin; Wutte; Xu; Cerny

    2000-05-29

    A light-element radioactive ion-beam capability has been developed at the LBNL 88-Inch Cyclotron. The system is based on the coupled-cyclotrons method and utilizes short-lived species, e.g., 11C, 14O, 13N produced by (p,n) and (p,alpha) reactions at the LBNL Biomedical Isotope Facility Cyclotron. In a first experiment, 197Au(11C,xn)208-xAt excitation functions have been measured for energies ranging from the Coulomb barrier up to 110 MeV using a beam of 11C with intensities up to (1-2)x10(8) ions/sec on target. The results of this experiment are compared to measurements of 197Au(12C, xn)209-xAt excitation functions. PMID:10990868

  8. Small glitches: the role of strange nuggets?

    NASA Astrophysics Data System (ADS)

    Lai, Xiao-Yu; Xu, Ren-Xin

    2016-03-01

    Pulsar glitches, i.e. the sudden spin-ups of pulsars, have been detected for most known pulsars. The mechanism giving rise to this kind of phenomenon is uncertain, although a large data set has been built. In the framework of the starquake model, based on Baym & Pines, the glitch sizes (the relative increases of spin-frequencies during glitches) ΔΩ/Ω depend on the released energies during glitches, with less released energies corresponding to smaller glitch sizes. On the other hand, as one of the dark matter candidates, our Galaxy might be filled with so called strange nuggets (SNs) which are relics from the early Universe. In this case collisions between pulsars and SNs are inevitable, and these collisions would lead to glitches when enough elastic energy has been accumulated during the spin-down process. The SN-triggered glitches could release less energy, because the accumulated elastic energy would be less than that in the scenario of glitches without SNs. Therefore, if a pulsar is hit frequently by SNs, it would tend to have more small glitches, whose values of ΔΩ/Ω are smaller than those in the standard starquake model (with larger amounts of released energy). Based on the assumption that in our Galaxy the distribution of SNs is similar to that of dark matter, as well as on the glitch data in the ATNF Pulsar Catalogue and Jodrell Bank glitch table, we find that in our Galaxy the incidences of small glitches exhibit tendencies consistent with the collision rates between pulsars and SNs. Further testing of this scenario is expected by detecting more small glitches (e.g., by the Square Kilometre Array).

  9. The Strange (Hi)story of Particles and Waves

    NASA Astrophysics Data System (ADS)

    Zeh, H. Dieter

    2016-03-01

    This is an attempt of a non-technical but conceptually consistent presentation of quantum theory in a historical context. While the first part is written for a general readership, Section 5 may appear a bit provocative to some quantum physicists. I argue that the single-particle wave functions of quantum mechanics have to be correctly interpreted as field modes that are "occupied once" (i.e. first excited states of the corresponding quantum oscillators in the case of boson fields). Multiple excitations lead to apparent many-particle wave functions, while the quantum states proper are defined by wave function(al)s on the "configuration" space of fundamental fields, or on another, as yet elusive, fundamental local basis.

  10. R-mode Instability of Low-mass Bare Strange Stars

    NASA Astrophysics Data System (ADS)

    Chun-mei, Pi; Shu-hua, Yang

    2016-04-01

    The r-mode instability window of low-mass strange stars is studied using the modified bag model of strange quark matter and reasonable sets of parameters. The results show that the ultimate spin frequency of strange stars increases with the decreasing stellar mass, and the highest spin frequency (716 Hz) of pulsars observed sofar can be explained by the bare strange stars with a mass lower than about 0.1∼0.2 M⊙, depending on the selected parameters.

  11. Isospin-symmetry breaking effects on the strange electric and magnetic form factors of the nucleon

    SciTech Connect

    Xia Zhengtong; Zuo Wei

    2008-07-15

    We examine the electric and magnetic strange form factors of the nucleon in the pseudoscalar-vector SU(3) Skyrme model, with special emphasis on the effects of isospin symmetry breaking (ISB). It is found that ISB has a nontrivial effect on the strange vector form factors of the nucleon and its contribution to the nucleon strangeness is significantly larger than one might naively expect. Our calculations and discussions may be of some significance for the experimental extraction of the authentic strangeness.

  12. Coalescence of Strange-quark Planets with Strange Stars: a New Kind of Source for Gravitational Wave Bursts

    NASA Astrophysics Data System (ADS)

    Geng, J. J.; Huang, Y. F.; Lu, T.

    2015-05-01

    Strange-quark matter (SQM) may be the true ground state of hadronic matter, indicating that the observed pulsars may actually be strange stars (SSs), but not neutron stars. According to the SQM hypothesis, the existence of a hydrostatically stable sequence of SQM stars has been predicted, ranging from 1 to 2 solar mass SSs, to smaller strange dwarfs and even strange planets. While gravitational wave (GW) astronomy is expected to open a new window to the universe, it will shed light on the search for SQM stars. Here we show that due to their extreme compactness, strange planets can spiral very close to their host SSs without being tidally disrupted. Like inspiraling neutron stars or black holes, these systems would serve as new sources of GW bursts, producing strong GWs at the final stage. The events occurring in our local universe can be detected by upcoming GW detectors, such as Advanced LIGO and the Einstein Telescope. This effect provides a unique probe to SQM objects and is hopefully a powerful tool for testing the SQM hypothesis.

  13. Fast pulsars, compact stars, and the strange matter hypothesis

    SciTech Connect

    Weber, F.; Glendenning, N.K.

    1993-03-17

    Part one of this paper deals with the recent finding of the possible existence of a mixed phase of baryon matter and quark matter inside neutron stars. In part two we review the theoretically determined minimum rotational periods of neutron stars, which serve to distinguish between pulsars that can be understood as rotating neutron stars and those that can not. Likely candidates for the latter are hypothetical strange stars. Their mass-radius relationship is discussed in the last part. It is pointed out that strange stars with a nuclear crust can give rise to the observed phenomena of pulsar glitches, thus passing the only astrophysical test of the strange-matter hypothesis existing to date.

  14. Highly efficient implementation of pseudospectral time-dependent density-functional theory for the calculation of excitation energies of large molecules.

    PubMed

    Cao, Yixiang; Hughes, Thomas; Giesen, Dave; Halls, Mathew D; Goldberg, Alexander; Vadicherla, Tati Reddy; Sastry, Madhavi; Patel, Bhargav; Sherman, Woody; Weisman, Andrew L; Friesner, Richard A

    2016-06-15

    We have developed and implemented pseudospectral time-dependent density-functional theory (TDDFT) in the quantum mechanics package Jaguar to calculate restricted singlet and restricted triplet, as well as unrestricted excitation energies with either full linear response (FLR) or the Tamm-Dancoff approximation (TDA) with the pseudospectral length scales, pseudospectral atomic corrections, and pseudospectral multigrid strategy included in the implementations to improve the chemical accuracy and to speed the pseudospectral calculations. The calculations based on pseudospectral time-dependent density-functional theory with full linear response (PS-FLR-TDDFT) and within the Tamm-Dancoff approximation (PS-TDA-TDDFT) for G2 set molecules using B3LYP/6-31G*(*) show mean and maximum absolute deviations of 0.0015 eV and 0.0081 eV, 0.0007 eV and 0.0064 eV, 0.0004 eV and 0.0022 eV for restricted singlet excitation energies, restricted triplet excitation energies, and unrestricted excitation energies, respectively; compared with the results calculated from the conventional spectral method. The application of PS-FLR-TDDFT to OLED molecules and organic dyes, as well as the comparisons for results calculated from PS-FLR-TDDFT and best estimations demonstrate that the accuracy of both PS-FLR-TDDFT and PS-TDA-TDDFT. Calculations for a set of medium-sized molecules, including Cn fullerenes and nanotubes, using the B3LYP functional and 6-31G(**) basis set show PS-TDA-TDDFT provides 19- to 34-fold speedups for Cn fullerenes with 450-1470 basis functions, 11- to 32-fold speedups for nanotubes with 660-3180 basis functions, and 9- to 16-fold speedups for organic molecules with 540-1340 basis functions compared to fully analytic calculations without sacrificing chemical accuracy. The calculations on a set of larger molecules, including the antibiotic drug Ramoplanin, the 46-residue crambin protein, fullerenes up to C540 and nanotubes up to 14×(6,6), using the B3LYP functional and 6-31G

  15. High-pT azimuthal correlations of neutral strange baryons and mesons in STAR at RHIC

    SciTech Connect

    Bielcikova, Jana

    2006-07-11

    We present results on two-particle azimuthal correlations of high-pT neutral strange baryons ({lambda},{lambda}-bar) and mesons (K{sub S}{sup 0}) associated with non-identified charged particles in d+Au and Au+Au collisions at {radical}(s{sub NN}) = 200 GeV. In particular, we discuss properties of the near-side yield of associated charged particles as a function of centrality, transverse momentum and zT, as well as possible baryon/meson and particle/antiparticle differences. The results are compared to the proton and pion triggered correlations and to fragmentation and recombination models.

  16. Production of neutral strange particles in muon-nucleon scattering at 490 GeV

    NASA Astrophysics Data System (ADS)

    Adams, M. R.; Aderholz, M.; Aïd, S.; Anthony, P. L.; Baker, M. D.; Bartlett, J.; Bhatti, A. A.; Braun, H. M.; Busza, W.; Conrad, J. M.; Coutrakon, G.; Davisson, R.; Derado, I.; Dhawan, S. K.; Dougherty, W.; Dreyer, T.; Dziunikowska, K.; Eckardt, V.; Ecker, U.; Erdmann, M.; Eskreys, A.; Figiel, J.; Gebauer, H. J.; Geesaman, D. F.; Gilman, R.; Green, M. C.; Haas, J.; Halliwell, C.; Hanlon, J.; Hantke, D.; Hughes, V. W.; Jackson, H. E.; Jaffe, D. E.; Jancso, G.; Jansen, D. M.; Kadija, K.; Kaufman, S.; Kennedy, R. D.; Kirk, T.; Kobrak, H. G. E.; Krzywdzinski, S.; Kunori, S.; Lord, J. J.; Lubatti, H. J.; McLeod, D.; Magill, S.; Malecki, P.; Manz, A.; Melanson, H.; Michael, D. G.; Mohr, W.; Montgomery, H. E.; Morfin, J. G.; Nickerson, R. B.; O'Day, S.; Olkiewicz, K.; Osborne, L.; Papavassiliou, V.; Pawlik, B.; Pipkin, F. M.; Ramberg, E. J.; Röser, A.; Ryan, J. J.; Salgado, C. W.; Salvarani, A.; Schellman, H.; Schmitt, M.; Schmitz, N.; Schüler, K. P.; Seyerlein, H. J.; Skuja, A.; Snow, G. A.; Söldner-Rembold, S.; Steinberg, P. H.; Stier, H. E.; Stopa, P.; Swanson, R. A.; Talaga, R.; Tentindo-Repond, S.; Trost, H. J.; Venkataramania, H.; Wilhelm, M.; Wilkes, J.; Wilson, R.; Wittek, W.; Wolbers, S. A.; Zhao, T.

    1994-12-01

    The production of K 0, Λ andbar Λ particles is studied in the E665 muon-nucleon experiment at Fermilab. The average multiplicities and squared transverse momenta are measured as a function of x F and W 2. Most features of the data can be well described by the Lund model. Within this model, the data on the K0/π± ratios and on the average K 0 multiplicity in the forward region favor a strangeness suppression factor s/u in the fragmentation process near 0.20. Clear evidence for QCD effects is seen in the average squared transverse momentum of K 0 and Λ particles.

  17. Using the Moon as a Strange Quark Nugget Detector

    NASA Astrophysics Data System (ADS)

    Herrin, Eugene T.; Rosenbaum, Doris C.; Teplitz, Vigdor L.

    2007-11-01

    We review the romance and mystery of strange quark matter (SQM), including: its basics, our recent work on bounds on the abundance of ton-range strange quark nuggets (SQNs) from Earth seismology, potential SQN bounds from a possible seismic search on the Moon, and our recent bounds on SQNs in the 10 kilogram to ton range from the data of Apollo-implanted seismometers. Finally, we speculate a bit on using the sun or the solar system to detect passage of SQNs of much greater mass than the aforementioned.

  18. Critical Assessment of Time-Dependent Density Functional Theory for Excited States of Open-Shell Systems: II. Doublet-Quartet Transitions.

    PubMed

    Li, Zhendong; Liu, Wenjian

    2016-06-14

    Compared with closed-shell systems, open-shell systems place three additional challenges to time-dependent density functional theory (TD-DFT) for electronically excited states: (a) the spin-contamination problem is a serious issue; (b) the exchange-correlation (XC) kernel may be numerically instable; and (c) the single-determinant description of open-shell ground states readily becomes energetically instable. Confined to flip-up single excitations, the spin-contamination problem can largely be avoided by using the spin-flip TD-DFT (SF-TD-DFT) formalism, provided that a noncollinear XC kernel is employed. As for the numerical instabilities associated with such a kernel, only an ad hoc scheme has been proposed so far, viz., the ALDA0 kernel, which amounts to setting the divergent components (arising from density gradients and kinetic energy density) simply to zero. The ground-state instability problem can effectively be avoided by introducing the Tamm-Dancoff approximation (TDA) to TD-DFT. Therefore, on a general basis, the SF-TDA/ALDA0 Ansatz is so far the only promising means within the TD-DFT framework for flip-up single excitations of open-shell systems. To assess systematically the performance of SF-TDA/ALDA0, in total 61 low-lying quartet excited states of the benchmark set of 11 small radicals [J. Chem. Theory Comput. 2016, 12, 238] are investigated with various XC functionals. Taking the MRCISD+Q (multireference configuration interaction with singles and doubles plus the Davidson correction) results as benchmark, it is found that the mean absolute errors of SF-TDA/ALDA0 with the SAOP (statistical averaging of model orbital potentials), global hybrid, and range-separated hybrid functionals are in the range of 0.2-0.4 eV. This is in line not only with the typical accuracy of TD-DFT for singlet and triplet excited states of closed-shell systems but also with the gross accuracy of spin-adapted TD-DFT for spin-conserving excited states of open-shell systems. PMID

  19. Synthesis and functionalization of monodisperse near-ultraviolet and visible excitable multifunctional Eu3+, Bi3+:REVO4 nanophosphors for bioimaging and biosensing applications

    NASA Astrophysics Data System (ADS)

    Escudero, Alberto; Carrillo-Carrión, Carolina; Zyuzin, Mikhail V.; Ashraf, Sumaira; Hartmann, Raimo; Núñez, Nuria O.; Ocaña, Manuel; Parak, Wolfgang J.

    2016-06-01

    Near-ultraviolet and visible excitable Eu- and Bi-doped NPs based on rare earth vanadates (REVO4, RE = Y, Gd) have been synthesized by a facile route from appropriate RE precursors, europium and bismuth nitrate, and sodium orthovanadate, by homogeneous precipitation in an ethylene glycol/water mixture at 120 °C. The NPs can be functionalized either by a one-pot synthesis with polyacrylic acid (PAA) or by a Layer-by-Layer approach with poly(allylamine hydrochloride) (PAH) and PAA. In the first case, the particle size can also be tuned by adjusting the amount of PAA. The Eu- Bi-doped REVO4 based nanophosphors show the typical red luminescence of Eu(iii), which can be excited through an energy transfer process from the vanadate anions, resulting in a much higher luminescence intensity in comparison to the direct excitation of the europium cations. The incorporation of Bi into the REVO4 structure shifts the original absorption band of the vanadate anions towards longer wavelengths, giving rise to nanophosphors with an excitation maximum at 342 nm, which can also be excited in the visible range. The suitability of such nanophosphors for bioimaging and biosensing applications, as well as their colloidal stability in different buffer media of biological interest, their cytotoxicity, their degradability at low pH, and their uptake by HeLa cells have been evaluated. Their suitability for bioimaging and biosensing applications is also demonstrated.Near-ultraviolet and visible excitable Eu- and Bi-doped NPs based on rare earth vanadates (REVO4, RE = Y, Gd) have been synthesized by a facile route from appropriate RE precursors, europium and bismuth nitrate, and sodium orthovanadate, by homogeneous precipitation in an ethylene glycol/water mixture at 120 °C. The NPs can be functionalized either by a one-pot synthesis with polyacrylic acid (PAA) or by a Layer-by-Layer approach with poly(allylamine hydrochloride) (PAH) and PAA. In the first case, the particle size can also be

  20. Asymptotic correction of the exchange-correlation kernel of time-dependent density functional theory for long-range charge-transfer excitations

    NASA Astrophysics Data System (ADS)

    Gritsenko, Oleg; Baerends, Evert Jan

    2004-07-01

    Time-dependent density functional theory (TDDFT) calculations of charge-transfer excitation energies ωCT are significantly in error when the adiabatic local density approximation (ALDA) is employed for the exchange-correlation kernel fxc. We relate the error to the physical meaning of the orbital energy of the Kohn-Sham lowest unoccupied molecular orbital (LUMO). The LUMO orbital energy in Kohn-Sham DFT—in contrast to the Hartree-Fock model—approximates an excited electron, which is correct for excitations in compact molecules. In CT transitions the energy of the LUMO of the acceptor molecule should instead describe an added electron, i.e., approximate the electron affinity. To obtain a contribution that compensates for the difference, a specific divergence of fxc is required in rigorous TDDFT, and a suitable asymptotically correct form of the kernel fxcasymp is proposed. The importance of the asymptotic correction of fxc is demonstrated with the calculation of ωCT(R) for the prototype diatomic system HeBe at various separations R(He-Be). The TDDFT-ALDA curve ωCT(R) roughly resembles the benchmark ab initio curve ωCTCISD(R) of a configuration interaction calculation with single and double excitations in the region R=1-1.5 Å, where a sizable He-Be interaction exists, but exhibits the wrong behavior ωCT(R)≪ωCTCISD(R) at large R. The TDDFT curve obtained with fxcasymp however approaches ωCTCISD(R) closely in the region R=3-10 Å. Then, the adequate rigorous TDDFT approach should interpolate between the LDA/GGA ALDA xc kernel for excitations in compact systems and fxcasymp for weakly interacting fragments and suitable interpolation expressions are considered.

  1. In Vitro Assessment Reveals Parameters-Dependent Modulation on Excitability and Functional Connectivity of Cerebellar Slice by Repetitive Transcranial Magnetic Stimulation

    PubMed Central

    Tang, Rongyu; Zhang, Guanghao; Weng, Xiechuan; Han, Yao; Lang, Yiran; Zhao, Yuwei; Zhao, Xiaobo; Wang, Kun; Lin, Qiuxia; Wang, Changyong

    2016-01-01

    Repetitive transcranial magnetic stimulation (rTMS) is an increasingly common technique used to selectively modify neural excitability and plasticity. There is still controversy concerning the cortical response to rTMS of different frequencies. In this study, a novel in vitro paradigm utilizing the Multi-Electrodes Array (MEA) system and acute cerebellar slicing is described. In a controllable environment that comprises perfusion, incubation, recording and stimulation modules, the spontaneous single-unit spiking activity in response to rTMS of different frequencies and powers was directly measured and analyzed. Investigation using this in vitro paradigm revealed frequency-dependent modulation upon the excitability and functional connectivity of cerebellar slices. The 1-Hz rTMS sessions induced short-term inhibition or lagged inhibition, whereas 20-Hz sessions induced excitation. The level of modulation is influenced by the value of power. However the long-term response fluctuated without persistent direction. The choice of evaluation method may also interfere with the interpretation of modulation direction. Furthermore, both short-term and long-term functional connectivity was strengthened by 1-Hz rTMS and weakened by 20-Hz rTMS. PMID:27000527

  2. On the truncation of the number of excited states in density functional theory sum-over-states calculations of indirect spin spin coupling constants

    SciTech Connect

    Zarycz, M. Natalia C. Provasi, Patricio F.; Sauer, Stephan P. A.

    2015-12-28

    It is investigated, whether the number of excited (pseudo)states can be truncated in the sum-over-states expression for indirect spin-spin coupling constants (SSCCs), which is used in the Contributions from Localized Orbitals within the Polarization Propagator Approach and Inner Projections of the Polarization Propagator (IPPP-CLOPPA) approach to analyzing SSCCs in terms of localized orbitals. As a test set we have studied the nine simple compounds, CH{sub 4}, NH{sub 3}, H{sub 2}O, SiH{sub 4}, PH{sub 3}, SH{sub 2}, C{sub 2}H{sub 2}, C{sub 2}H{sub 4}, and C{sub 2}H{sub 6}. The excited (pseudo)states were obtained from time-dependent density functional theory (TD-DFT) calculations with the B3LYP exchange-correlation functional and the specialized core-property basis set, aug-cc-pVTZ-J. We investigated both how the calculated coupling constants depend on the number of (pseudo)states included in the summation and whether the summation can be truncated in a systematic way at a smaller number of states and extrapolated to the total number of (pseudo)states for the given one-electron basis set. We find that this is possible and that for some of the couplings it is sufficient to include only about 30% of the excited (pseudo)states.

  3. Excited Protein States of Human Tear Lipocalin for Low- and High-Affinity Ligand Binding Revealed by Functional AB Loop Motion

    PubMed Central

    Gasymov, Oktay K.; Abduragimov, Adil R.; Glasgow, Ben J.

    2010-01-01

    Human tear lipocalin (TL), a prominent member of lipocalin family, exhibits functional and structural promiscuity. The plasticity of loop regions modulates entry to the ligand pocket at the “open” end of the eight-stranded β-barrel. Site directed multi-distance measurements using fluorescence resonance energy transfer between functional loops register two excited protein states for low- and high-affinity ligand binding. At low pH, the longest loop AB adopts the conformation of the low-affinity excited protein state that matches the crystal structure of holo-TL at pH 8. A “crankshaft” like movement is detected for the loop AB in a low pH transition. At pH 7.3 the holo-protein assumes a high-affinity excited protein state, in which the loop AB is more compact (RMS= 3.1Å). In the apo-holo transition, the reporter Trp 28 moves about 4.5 Å that reflects a decrease in distance between Glu27 and Lys108. This interaction fixes the loop AB conformation for the high-affinity mode. No such of movement is detected at low pH, where Glu27 is protonated. Data strongly indicate that the protonation state of Glu27 modulates the conformation of the loop AB for high- and low-affinity binding. PMID:20439130

  4. Complementary functions of SK and Kv7/M potassium channels in excitability control and synaptic integration in rat hippocampal dentate granule cells

    PubMed Central

    Mateos-Aparicio, Pedro; Murphy, Ricardo; Storm, Johan F

    2014-01-01

    The dentate granule cells (DGCs) form the most numerous neuron population of the hippocampal memory system, and its gateway for cortical input. Yet, we have only limited knowledge of the intrinsic membrane properties that shape their responses. Since SK and Kv7/M potassium channels are key mechanisms of neuronal spiking and excitability control, afterhyperpolarizations (AHPs) and synaptic integration, we studied their functions in DGCs. The specific SK channel blockers apamin or scyllatoxin increased spike frequency (excitability), reduced early spike frequency adaptation, fully blocked the medium-duration AHP (mAHP) after a single spike or spike train, and increased postsynaptic EPSP summation after spiking, but had no effect on input resistance (Rinput) or spike threshold. In contrast, blockade of Kv7/M channels by XE991 increased Rinput, lowered the spike threshold, and increased excitability, postsynaptic EPSP summation, and EPSP–spike coupling, but only slightly reduced mAHP after spike trains (and not after single spikes). The SK and Kv7/M channel openers 1-EBIO and retigabine, respectively, had effects opposite to the blockers. Computational modelling reproduced many of these effects. We conclude that SK and Kv7/M channels have complementary roles in DGCs. These mechanisms may be important for the dentate network function, as CA3 neurons can be activated or inhibition recruited depending on DGC firing rate. PMID:24366266

  5. Excited protein states of human tear lipocalin for low- and high-affinity ligand binding revealed by functional AB loop motion.

    PubMed

    Gasymov, Oktay K; Abduragimov, Adil R; Glasgow, Ben J

    2010-06-01

    Human tear lipocalin (TL), a prominent member of lipocalin family, exhibits functional and structural promiscuity. The plasticity of loop regions modulates entry to the ligand pocket at the "open" end of the eight-stranded beta-barrel. Site-directed multi-distance measurements using fluorescence resonance energy transfer between functional loops register two excited protein states for low- and high-affinity ligand binding. At low pH, the longest loop AB adopts the conformation of the low-affinity excited protein state that matches the crystal structure of holo-TL at pH 8. A "crankshaft" like movement is detected for the loop AB in a low pH transition. At pH 7.3 the holo-protein assumes a high-affinity excited protein state, in which the loop AB is more compact (RMS=3.1A). In the apo-holo transition, the reporter Trp 28 moves about 4.5A that reflects a decrease in distance between Glu27 and Lys108. This interaction fixes the loop AB conformation for the high-affinity mode. No such movement is detected at low pH, where Glu27 is protonated. Data strongly indicate that the protonation state of Glu27 modulates the conformation of the loop AB for high- and low-affinity binding. PMID:20439130

  6. Excitation functions for production of heavy actinides from interactions of /sup 40/Ca and /sup 48/Ca ions with /sup 248/Cm

    SciTech Connect

    Hoffman, D.C.; Fowler, M.M.; Daniels, W.R.; von Gunten, H.R.; Lee, D.; Moody, K.J.; Gregorich, K.; Welch, R.; Seaborg, G.T.; Bruechle, W.

    1985-05-01

    Excitation functions have been measured for production of isotopes of Bk through Fm in bombardments of /sup 248/Cm with 234- to 294-MeV /sup 40/Ca ions and with 239- to 318-MeV /sup 48/Ca ions. The maxima of the isotopic distributions for these elements occur at only 2 to 3 mass numbers larger for /sup 48/Ca than for /sup 40/Ca reactions. The shapes of the distributions and the half-widths of about 2.5 mass numbers are quite similar to those observed previously for reactions of /sup 16/O, /sup 18/O, /sup 20/Ne, and /sup 22/Ne with /sup 248/Cm. In general, the excitation functions for /sup 40/Ca show maxima near the Coulomb barrier while those for /sup 48/Ca are about 20 MeV above the barrier. The cross sections decrease rather slowly with increasing projectile energy over the energy range studied, indicating that the additional projectile energy is not manifested as excitation energy of these actinide products.

  7. On the truncation of the number of excited states in density functional theory sum-over-states calculations of indirect spin spin coupling constants

    NASA Astrophysics Data System (ADS)

    Zarycz, M. Natalia C.; Provasi, Patricio F.; Sauer, Stephan P. A.

    2015-12-01

    It is investigated, whether the number of excited (pseudo)states can be truncated in the sum-over-states expression for indirect spin-spin coupling constants (SSCCs), which is used in the Contributions from Localized Orbitals within the Polarization Propagator Approach and Inner Projections of the Polarization Propagator (IPPP-CLOPPA) approach to analyzing SSCCs in terms of localized orbitals. As a test set we have studied the nine simple compounds, CH4, NH3, H2O, SiH4, PH3, SH2, C2H2, C2H4, and C2H6. The excited (pseudo)states were obtained from time-dependent density functional theory (TD-DFT) calculations with the B3LYP exchange-correlation functional and the specialized core-property basis set, aug-cc-pVTZ-J. We investigated both how the calculated coupling constants depend on the number of (pseudo)states included in the summation and whether the summation can be truncated in a systematic way at a smaller number of states and extrapolated to the total number of (pseudo)states for the given one-electron basis set. We find that this is possible and that for some of the couplings it is sufficient to include only about 30% of the excited (pseudo)states.

  8. Optical excitation function of H(1s-2p) produced by electron impact from threshold to 1.8 keV

    SciTech Connect

    James, G.K.; Slevin, J.A.; Shemansky, D.E.; McConkey, J.W.; Bray, I.; Dziczek, D.; Kanik, I.; Ajello, J.M.

    1997-02-01

    The optical excitation function of prompt Lyman-{alpha} radiation, produced by electron impact on atomic hydrogen, has been measured over the extended energy range from threshold to 1.8 keV. Measurements were obtained in a crossed-beams experiment using both magnetically confined and electrostatically focused electrons in collision with atomic hydrogen produced by an intense discharge source. A vacuum-ultraviolet monochromator system was used to measure the emitted Lyman-{alpha} radiation. The absolute H(1s-2p) electron impact excitation cross section was obtained from the experimental optical excitation function by normalizing to the accepted optical oscillator strength, with corrections for polarization and cascade. Our data are significantly different from the earlier experimental results and which are limited to energies below 200 eV. Statistical and known systematic uncertainties in our data range from {plus_minus}4{percent} near threshold to {plus_minus}2{percent} at 1.8 keV. Multistate coupling affecting the shape of the excitation function up to 1 keV impact energy is apparent in both the present experimental data and present theoretical results obtained with convergent close-coupling (CCC) theory. This shape function effect leads to an uncertainty in absolute cross sections at the 10{percent} level in the analysis of the experimental data. The derived optimized absolute cross sections are within 7{percent} of the CCC calculations over the 14 eV{endash}1.8 keV range. The present CCC calculations converge on the Bethe-Fano profile for H(1s-2p) excitation at high energy. For this reason agreement with the CCC values to within 3{percent} is achieved in a nonoptimal normalization of the experimental data to the Bethe-Fano profile. The fundamental H(1s-2p) electron impact cross section is thereby determined to an unprecedented accuracy over the 14 eV {endash} 1.8 keV energy range. (Abstract Truncated)

  9. Ultrafast dynamics of the dielectric functions of ZnO and BaTiO{sub 3} thin films after intense femtosecond laser excitation

    SciTech Connect

    Acharya, S.; Seifert, G.; Chouthe, S.; Graener, H.; Böntgen, T.; Sturm, C.; Schmidt-Grund, R.; Grundmann, M.

    2014-02-07

    The ultrafast carrier dynamics of epitaxial ZnO and BaTiO{sub 3} thin films after intense excitation at 3.10 eV and 4.66 eV photon energy has been studied by femtosecond absorption spectroscopy. Modelling the transient transmission changes on the basis of spectroscopic ellipsometry data and pertinent equilibrium model dielectric functions extended by additional terms for the effects at high carrier density (P-band luminescence and stimulated emission from electron-hole-plasma), a self-consistent parameterized description was obtained for both materials. Excited carrier lifetimes in the range of ≈2 to ≈60 ps and long-lived thermal effects after several hundred ps have been identified in both materials. These findings form a reliable basis to quantitatively describe future femtosecond studies on ZnO/BaTiO{sub 3} heterolayer systems.

  10. Source mechanism of long-period events at Kusatsu-Shirane Volcano, Japan, inferred from waveform inversion of the effective excitation functions

    USGS Publications Warehouse

    Nakano, M.; Kumagai, H.; Chouet, B.A.

    2003-01-01

    We investigate the source mechanism of long-period (LP) events observed at Kusatsu-Shirane Volcano, Japan, based on waveform inversions of their effective excitation functions. The effective excitation function, which represents the apparent excitation observed at individual receivers, is estimated by applying an autoregressive filter to the LP waveform. Assuming a point source, we apply this method to seven LP events the waveforms of which are characterized by simple decaying and nearly monochromatic oscillations with frequency in the range 1-3 Hz. The results of the waveform inversions show dominant volumetric change components accompanied by single force components, common to all the events analyzed, and suggesting a repeated activation of a sub-horizontal crack located 300 m beneath the summit crater lakes. Based on these results, we propose a model of the source process of LP seismicity, in which a gradual buildup of steam pressure in a hydrothermal crack in response to magmatic heat causes repeated discharges of steam from the crack. The rapid discharge of fluid causes the collapse of the fluid-filled crack and excites acoustic oscillations of the crack, which produce the characteristic waveforms observed in the LP events. The presence of a single force synchronous with the collapse of the crack is interpreted as the release of gravitational energy that occurs as the slug of steam ejected from the crack ascends toward the surface and is replaced by cooler water flowing downward in a fluid-filled conduit linking the crack and the base of the crater lake. ?? 2003 Elsevier Science B.V. All rights reserved.

  11. Measuring Infant-Mother Attachment: Is the Strange Situation Enough?

    ERIC Educational Resources Information Center

    Clarke-Stewart, K. Alison; Goossens, Frits A.; Allhusen, Virginia D.

    2001-01-01

    Examined validity of the California Attachment Procedure (CAP), which does not involve mother-child separations. Overall, toddlers were more likely to be classified as secure in the CAP than in the Strange Situation (SS) test. The CAP yielded higher rates of security, particularly for children in day care, and security in the CAP correlated more…

  12. Familiar-Strange: Teaching the Scripture as John Would Teach

    ERIC Educational Resources Information Center

    Ha, Tung-Chiew

    2014-01-01

    The Gospel of John teaches through telling the story of Jesus in light of the familiar Hebrew faith stories. It is an interpretive task that presents Jesus to his audience and teaches them adequate faith. John the Teacher skillfully uses narrative skills to create the familiar-strange effect in his storytelling. Each story is followed by a…

  13. Strange particle production in neutrino-neon charged current interactions

    SciTech Connect

    Plano, R.; Baker, N.J.; Connolly, P.L.; Kahn, S.A.; Murtagh, M.J.; Palmer, R.B.; Samios, N.P.; Tanaka, M.; Baltay, C.; Bregman, M.

    1986-01-01

    Neutral strange particle production in charged-current muon-neutrino interactions have been studied in the Fermilab 15-foot neon bubble chamber. Associated production is expected to be the major source of strange particles in charged-current neutrino interactions. sigma-neutral and xi-minus production by neutrinos was observed. The dependence on various leptonic and hadronic variables is investigated. A fit to single and associated production of s, s/anti-s, and c quarks is described based on the number of single and double strange particle production events. Inclusive neutral strange particle decays (V/sup 0/) production rates as a fraction of all charged-current events are measured and are tabulated. The lambda/K ratio is found to be 0.39 +- 0.04 and the fraction of lambda coming from sigma-neutral is (16 +- 5)%. The single- and double V/sup 0/ production was used to determine the associated s anti-s production rate and single s-quark production rate. 13 refs., 7 figs., 3 tabs. (LEW)

  14. Properties of bare strange stars associated with surface electric fields

    SciTech Connect

    Picanco Negreiros, Rodrigo; Mishustin, Igor N.; Schramm, Stefan; Weber, Fridolin

    2010-11-15

    In this paper we investigate the electrodynamic surface properties of bare strange quark stars. The surfaces of such objects are characterized by the formation of ultrahigh electric surface fields which might be as high as {approx}10{sup 19} V/cm. These fields result from the formation of electric dipole layers at the stellar surfaces. We calculate the increase in gravitational mass associated with the energy stored in the electric dipole field, which turns out to be only significant if the star possesses a sufficiently strong net electric charge distribution. In the second part of the paper, we explore the intriguing possibility of what happens when the electron layer (sphere) rotates with respect to the stellar strange matter body. We find that in this event magnetic fields can be generated which, for moderate effective rotational frequencies between the electron layer and the stellar body, agree with the magnetic fields inferred for several central compact objects. These objects could thus be comfortably interpreted as strange stars whose electron atmospheres rotate at frequencies that are moderately different ({approx}10 Hz) from the rotational frequencies of the strange star itself.

  15. Strange vector form factors from parity-violating electron scattering

    SciTech Connect

    Kent Paschke, Anthony Thomas, Robert Michaels, David Armstrong

    2011-06-01

    The simplest models might describe the nucleon as 3 light quarks, but this description would be incomplete without inclusion of the sea of glue and qbar q pairs which binds it. Early indications of a particularly large contribution from strange quarks in this sea to the spin and mass of the nucleon motivated an experimental program examining the role of these strange quarks in the nucleon vector form factors. The strangeness form factors can be extracted from the well-studied electromagnetic structure of the nucleon using parity-violation in electron-nuclear scattering to isolate the effect of the weak interaction. With high luminosity and polarization, and a very stable beam due to its superconducting RF cavities, CEBAF at Jefferson Lab is a precision instrument uniquely well suited to the challenge of measurements of the small parity-violating asymmetries. The techniques and results of the two major Jefferson Lab experimental efforts in parity-violation studies, HAPPEX and G0, as well as efforts to describe the strange form factors in QCD, will be reviewed.

  16. Some measurements for determining strangeness matrix elements in the nucleon

    SciTech Connect

    Henley, E.M.; Pollock, S.J.; Ying, S. ); Frederico, T. , Sao Jose dos Campos, SP . Inst. de Estudos Avancados); Krein, . Inst. de Fisica Teorica); Williams, A.G. )

    1991-01-01

    Some experiments to measure strangeness matrix elements of the proton are proposed. Two of these suggestions are described in some detail, namely electro-production of phi mesons and the difference between neutrino and antineutrino scattering for isospin zero targets such as deuterium.

  17. Some measurements for determining strangeness matrix elements in the nucleon

    SciTech Connect

    Henley, E.M.; Pollock, S.J.; Ying, S.; Frederico, T.; Krein,; Williams, A.G.

    1991-12-31

    Some experiments to measure strangeness matrix elements of the proton are proposed. Two of these suggestions are described in some detail, namely electro-production of phi mesons and the difference between neutrino and antineutrino scattering for isospin zero targets such as deuterium.

  18. Strangeness Production in Jets with ALICE at the LHC

    NASA Astrophysics Data System (ADS)

    Smith, Chrismond; Harton, Austin; Garcia, Edmundo; Alice Collaboration

    2016-03-01

    The study of strange particle production is an important tool for understanding the properties of the hot and dense QCD medium created in heavy-ion collisions at ultra-relativistic energies. The study of strange particles in these collisions provides information on parton fragmentation, a fundamental QCD process. While measurements at low and intermediate pT, are already in progress at the LHC, the study of high momentum observables is equally important for a complete understanding of the QCD matter, this can be achieved by studying jet interactions. We propose the measurement of the characteristics of the jets containing strange particles. Starting with proton-proton collisions, we have calculated the inclusive pTJet spectra and the spectra for jets containing strange particles (K-short or lambda), and we are extending this analysis to lead-lead collisions. In this talk the ALICE experiment will be described, the methodology used for the data analysis and the available results will be discussed. This material is based upon work supported by the National Science Foundation under Grants PHY-1305280 and PHY-1407051.

  19. Evidence for White Dwarfs with Strange-Matter Cores

    NASA Astrophysics Data System (ADS)

    Mathews, Grant J.; Suh, Insaeng; Lan, Nguyen Q.; Otsuki, Kaori; Weber, Fridolin

    2008-09-01

    We summarize masses and radii for a number of white dwarfs as deduced from a combination of proper motion studies, Hipparcos parallax distances, effective temperatures, and binary or spectroscopic masses. A puzzling feature of these data, however, is that some stars appear to have radii which are significantly smaller than that expected for a standard electron-degenerate white-dwarf equations of state. We construct a projection of white-dwarf radii for fixed effective mass and conclude that there is at least marginal evidence for bimodality in the radius distribution for white dwarfs. We argue that if such compact white dwarfs exist it is unlikely that they contain an iron core. We propose an alternative of strange-quark matter within the white-dwarf core. We also discuss the impact of the so-called color-flavor locked (CFL) state in strange-matter core associated with color superconductivity. We show that the data exhibit several features consistent with the expected mass-radius relation of strange dwarfs. We identify eight nearby white dwarfs which are possible candidates for strange matter cores and suggest observational tests of this hypothesis.

  20. Evidence for White Dwarfs with Strange-Matter Cores

    NASA Astrophysics Data System (ADS)

    Mathews, Grant; Suh, Insaeng; Lan, Nguyen; Zech, William; Otsuki, Kaori; Weber, Friedolin

    2006-10-01

    We summarize masses and radii for a number of white dwarfs as deduced from a combination of proper motion studies, Hipparcos parallax distances, effective temperatures, and binary or spectroscopic masses. A puzzling feature of these data, however, is that some stars appear to have radii which are significantly smaller than that expected for a standard electron-degenerate white-dwarf equations of state. We construct a projection of white-dwarf radii for fixed effective mass and conclude that there is at least marginal evidence for bimodality in the radius distribution for white dwarfs. We argue that if such compact white dwarfs exist it is unlikely that they contain an iron core. We propose an alternative of strange-quark matter within the white-dwarf core. We also discuss the impact of the so-called color-flavor locked (CFL) state in strange-matter core associated with color superconductivity. We show that the data exhibit several features consistent with the expected mass-radius relation of strange dwarfs. We identify eight nearby white dwarfs which are possible candidates for strange matter cores and suggest observational tests of this hypothesis.

  1. Analysis of white dwarfs with strange-matter cores

    NASA Astrophysics Data System (ADS)

    Mathews, G. J.; Suh, I.-S.; O'Gorman, B.; Lan, N. Q.; Zech, W.; Otsuki, K.; Weber, F.

    2006-06-01

    We summarize masses and radii for a number of white dwarfs as deduced from a combination of proper motion studies, Hipparcos parallax distances, effective temperatures and binary or spectroscopic masses. A puzzling feature of these data, however, is that some stars appear to have radii which are significantly smaller than that expected for a standard electron-degenerate white-dwarf equations of state. We construct a projection of white-dwarf radii for fixed effective mass and conclude that there is at least marginal evidence for bimodality in the radius distribution for white dwarfs. We argue that if such compact white dwarfs exist it is unlikely that they contain an iron core. We propose an alternative of strange-quark matter within the white-dwarf core. We also discuss the impact of the so-called color-flavour-locked (CFL) state in strange-matter core associated with color superconductivity. We show that the data exhibit several features consistent with the expected mass-radius relation of strange dwarfs. We identify eight nearby white dwarfs which are possible candidates for strange-matter cores and suggest observational tests of this hypothesis.

  2. Application of recent double-hybrid density functionals to low-lying singlet-singlet excitation energies of large organic compounds

    NASA Astrophysics Data System (ADS)

    Meo, F. Di; Trouillas, P.; Adamo, C.; Sancho-García, J. C.

    2013-10-01

    The present work assesses some recently developed double-hybrid density functionals (B2π-PLYP, PBE0-DH, and PBE0-2) using linear-response Tamm-Dancoff Time-Dependent Density Functional Theory. This assessment is achieved against experimentally derived low-lying excitation energies of large organic dyes of recent interest, including some excitations dominated by charge-transfer transitions. Comparisons are made with some of the best-performing methods established from the literature, such as PBE0 or B3LYP hybrid or the recently proposed B2-PLYP and B2GP-PLYP double-hybrid models, to ascertain their quality and robustness on equal footing. The accuracy of parameter-free or empirical forms of double-hybrid functionals is also briefly discussed. Generally speaking, it turns out that double-hybrid expressions always provide more accurate estimates than corresponding hybrid methods. Double-hybrid functionals actually reach averaged accuracies of 0.2 eV, that can be admittedly considered close to any intended accuracy limit within the present theoretical framework.

  3. Free electrons and ionic liquids: study of excited states by means of electron-energy loss spectroscopy and the density functional theory multireference configuration interaction method.

    PubMed

    Regeta, Khrystyna; Bannwarth, Christoph; Grimme, Stefan; Allan, Michael

    2015-06-28

    The technique of low energy (0-30 eV) electron impact spectroscopy, originally developed for gas phase molecules, is applied to room temperature ionic liquids (IL). Electron energy loss (EEL) spectra recorded near threshold, by collecting 0-2 eV electrons, are largely continuous, assigned to excitation of a quasi-continuum of high overtones and combination vibrations of low-frequency modes. EEL spectra recorded by collecting 10 eV electrons show predominantly discrete vibrational and electronic bands. The vibrational energy-loss spectra correspond well to IR spectra except for a broadening (∼0.04 eV) caused by the liquid surroundings, and enhanced overtone activity indicating a contribution from resonant excitation mechanism. The spectra of four representative ILs were recorded in the energy range of electronic excitations and compared to density functional theory multireference configuration interaction (DFT/MRCI) calculations, with good agreement. The spectra up to about 8 eV are dominated by π-π* transitions of the aromatic cations. The lowest bands were identified as triplet states. The spectral region 2-8 eV was empty in the case of a cation without π orbitals. The EEL spectrum of a saturated solution of methylene green in an IL band showed the methylene green EEL band at 2 eV, indicating that ILs may be used as a host to study nonvolatile compounds by this technique in the future. PMID:26018044

  4. Making the Familiar Strange and Making the Strange Familiar: Understanding Korean Children's Experiences of Living with an Autistic Sibling

    ERIC Educational Resources Information Center

    Hwang, Se Kwang; Charnley, Helen

    2010-01-01

    Based on the findings of a small-scale study using visual ethnographic techniques with nine South Korean children, this article explores the role of culture in understanding autism. While autism is embedded within the "strange" and "unfamiliar", linked to exclusion and discrimination in Korean society, the children focussed on reframing their…

  5. Measuring theory of mind across middle childhood: Reliability and validity of the Silent Films and Strange Stories tasks.

    PubMed

    Devine, Rory T; Hughes, Claire

    2016-09-01

    Recent years have seen a growth of research on the development of children's ability to reason about others' mental states (or "theory of mind") beyond the narrow confines of the preschool period. The overall aim of this study was to investigate the psychometric properties of a task battery composed of items from Happé's Strange Stories task and Devine and Hughes' Silent Film task. A sample of 460 ethnically and socially diverse children (211 boys) between 7 and 13years of age completed the task battery at two time points separated by 1month. The Strange Stories and Silent Film tasks were strongly correlated even when verbal ability and narrative comprehension were taken into account, and all items loaded onto a single theory-of-mind latent factor. The theory-of-mind latent factor provided reliable estimates of performance across a wide range of theory-of-mind ability and showed no evidence of differential item functioning across gender, ethnicity, or socioeconomic status. The theory-of-mind latent factor also exhibited strong 1-month test-retest reliability, and this stability did not vary as a function of child characteristics. Taken together, these findings provide evidence for the validity and reliability of the Strange Stories and Silent Film task battery as a measure of individual differences in theory of mind suitable for use across middle childhood. We consider the methodological and conceptual implications of these findings for research on theory of mind beyond the preschool years. PMID:26255713

  6. Electronic Excitations in Push-Pull Oligomers and Their Complexes with Fullerene from Many-Body Green's Functions Theory with Polarizable Embedding.

    PubMed

    Baumeier, Björn; Rohlfing, Michael; Andrienko, Denis

    2014-08-12

    We present a comparative study of excited states in push-pull oligomers of PCPDTBT and PSBTBT and prototypical complexes with a C60 acceptor using many-body Green's functions theory within the GW approximation and the Bethe-Salpeter equation. We analyze excitations in oligomers up to a length of 5 nm and find that for both materials the absorption energy practically saturates for structures larger than two repeat units due to the localized nature of the excitation. In the bimolecular complexes with C60, the transition from Frenkel to charge transfer excitons is generally exothermic and strongly influenced by the acceptor's position and orientation. The high CT binding energy of the order of 2 eV results from the lack of an explicit molecular environment. External polarization effects are then modeled in a GW-BSE based QM/MM approach by embedding the donor-acceptor complex into a polarizable lattice. The lowest charge transfer exciton is energetically stabilized by about 0.5 eV, while its binding energy is reduced to about 0.3 eV. We also identify a globally unbound charge transfer state with a more delocalized hole at higher energy while still within the absorption spectrum, which opens another potential pathway for charge separation. For both PCPDTBT and PSBTBT, the energetics are largely similar with respect to absorption and the driving force to form intermediate charge transfer excitations for free charge generation. These results support that the higher power conversion efficiency observed for solar cells using PSBTBT as donor material is a result of molecular packing rather than of the electronic structure of the polymer. PMID:26588281

  7. Ab initio calculations of accurate dissociation energy and analytic potential energy function for the second excited state B1Π of 7LiH

    NASA Astrophysics Data System (ADS)

    Shi, De-Heng; Liu, Yu-Fang; Sun, Jin-Feng; Zhu, Zun-Lue; Yang, Xiang-Dong

    2006-12-01

    The reasonable dissociation limit of the second excited singlet state B1Π of 7LiH molecule is obtained. The accurate dissociation energy and equilibrium geometry of the B1Π state are calculated using a symmetry-adapted-cluster configuration-interaction method in full active space. The whole potential energy curve for the B1Π state is obtained over the internuclear distance ranging from about 0.10 nm to 0.54 nm, and has a least-square fit to the analytic Murrell-Sorbie function form. The vertical excitation energy is calculated from the ground state to the B1Π state and compared with previous theoretical results. The equilibrium internuclear distance obtained by geometry optimization is found to be quite different from that obtained by single-point energy scanning under the same calculation condition. Based on the analytic potential energy function, the harmonic frequency value of the B1Π state is estimated. A comparison of the theoretical calculations of dissociation energies, equilibrium interatomic distances and the analytic potential energy function with those obtained by previous theoretical results clearly shows that the present work is more comprehensive and in better agreement with experiments than previous theories, thus it is an improvement on previous theories.

  8. Solvent effects on optical excitations of poly para phenylene ethynylene studied by QM/MM simulations based on many-body Green's functions theory

    NASA Astrophysics Data System (ADS)

    Bagheri, B.; Karttunen, M.; Baumeier, B.

    2016-07-01

    Electronic excitations in dilute solutions of poly para phenylene ethynylene (poly-PPE) are studied using a QM/MM approach combining many-body Green's functions theory within the GW approximation and the Bethe-Salpeter equation with polarizable force field models. Oligomers up to a length of 7.5 nm (10 repeat units) functionalized with nonyl side chains are solvated in toluene and water, respectively. After equilibration using atomistic molecular dynamics (MD), the system is partitioned into a quantum region (backbone) embedded into a classical (side chains and solvent) environment. Optical absorption properties are calculated solving the coupled QM/MM system self-consistently and special attention is paid to the effects of solvents. The model allows to differentiate the influence of oligomer conformation induced by the solvation from electronic effects related to local electric fields and polarization. It is found that the electronic environment contributions are negligible compared to the conformational dynamics of the conjugated PPE. An analysis of the electron-hole wave function reveals a sensitivity of energy and localization characteristics of the excited states to bends in the global conformation of the oligomer rather than to the relative of phenyl rings along the backbone.

  9. Angular distribution, kinetic energy distributions, and excitation functions of fast metastable oxygen fragments following electron impact of CO2

    NASA Technical Reports Server (NTRS)

    Misakian, M.; Mumma, M. J.; Faris, J. F.

    1975-01-01

    Dissociative excitation of CO2 by electron impact was studied using the methods of translational spectroscopy and angular distribution analysis. Earlier time of flight studies revealed two overlapping spectra, the slower of which was attributed to metastable CO(a3 pi) fragments. The fast peak is the focus of this study. Threshold energy, angular distribution, and improve time of flight measurements indicate that the fast peak actually consists of five overlapping features. The slowest of the five features is found to consist of metastable 0(5S) produced by predissociation of a sigma u + state of CO2 into 0(5S) + CO(a3 pi). Oxygen Rydberg fragments originating directly from a different sigma u + state are believed to make up the next fastest feature. Mechanisms for producing the three remaining features are discussed.

  10. The discrepant kinematics of recombination and collisionally excited lines in NGC 7009 as a function of ionization structure

    NASA Astrophysics Data System (ADS)

    Torres-Peimbert, S.; Richer, M. R.; Georgiev, L.; Arrieta, A.

    2014-10-01

    We have analyzed the kinematics of emission of the planetary nebula NGC 7009 from long slit spectroscopy from the UVES spectrograph at the VLT of ESO. In particular we are interested in comparing lines excited by recombination and collisions with electrons to determine whether similarities or differences could be useful in elucidating the well-known abundance discrepancy derived from them. We construct position-velocity maps for recombination, fluorescence, charge transfer, and collisionally excited lines.We find a plasma component emitting in the C II, N II, O II, and Ne II recombination lines whose kinematics are discrepant: they are incompatible with the ionization structure derived from all other evidence and the kinematics derived from all of these lines are unexpectedly very similar. We found direct evidence for a recombination contribution to [N II] λ5755. Once taken into account, the electron temperatures from [N II], [O III], and [Ne III] agree at a given position and velocity. The electron densities derived from [O II] and [Ar IV] are consistent with direct imaging and the distribution of hydrogen emission. The kinematics of the C II, N II, O II, and Ne II lines does not coincide with the kinematics of the [O III] and [Ne III] forbidden emission, indicating that there is an additional plasma component to the recombination emission that arises from a different volume from that giving rise to the forbidden emission from the parent ions within NGC 7009. Thus, the chemical abundances derived from either type of line are correct only for the plasma component from which they arise. Apart from [N II] λ5755, we find no anomaly with the forbidden lines usually used to determine chemical abundances in ionized nebulae, so the abundances derived from them should be reliable for the medium from which they arise.

  11. Description of electron transfer in the ground and excited states of organic donor–acceptor systems by single-reference and multi-reference density functional methods

    SciTech Connect

    Filatov, Michael

    2014-09-28

    Electron transfer in the ground and excited states of a model donor–acceptor (D–A) system is investigated using the single-reference and multi-reference density functional theory (DFT) methods. To analyze the results of the calculations, a simple two-site multi-reference model was derived that predicts a stepwise electron transfer in the S{sub 0} state and a wave-like dependence of the S{sub 1} electron transfer on the external stimulus. The standard single-reference Kohn-Sham (KS) DFT approach and the time-dependent DFT (TDDFT) method failed to describe the correct dependence of the S{sub 0} and S{sub 1} electron transfer on the external electric field applied along the donor–acceptor system. The multi-reference DFT approach, the spin-restricted ensemble-referenced KS (REKS) method, was able to successfully reproduce the correct behavior of the S{sub 0} and S{sub 1} electron transfer on the applied field. The REKS method was benchmarked against experimentally measured gas phase charge transfer excitations in a series of organic donor–acceptor complexes and displayed its ability to describe this type of electronic transitions with a very high accuracy, mean absolute error of 0.05 eV with the use of the standard range separated density functionals. On the basis of the calculations undertaken in this work, it is suggested that the non-adiabatic coupling between the S{sub 0} and S{sub 1} states may interfere with the electron transfer in a weakly coupled donor–acceptor system. It is also suggested that the electronic excitation of a D{sup +}–A{sup −} system may play a dual role by assisting the further electron transfer at certain magnitudes of the applied electric field and causing the backward transfer at lower electric field strengths.

  12. Collective, stochastic and nonequilibrium behavior of highly excited hadronic matter

    SciTech Connect

    Carruthers, P.

    1983-01-01

    We discuss selected problems concerning the dynamic and stochasticc behavior of highly excited matter, particularly the QCD plasma. For the latter we consider the equation of state, kinetics, quasiparticles, flow properties and possible chaos and turbulence. The promise of phase space distribution functions for covariant transport and kinetic theory is stressed. The possibility and implications of a stochastic bag are spelled out. A simplified space-time model of hadronic collisions is pursued, with applications to A-A collisions and other matters. The domain wall between hadronic and plasma phase is of potential importance: its thickness and relation to surface tension are noticed. Finally we reviewed the recently developed stochastic cell model of multiparticle distributions and KNO scaling. This topic leads to the notion that fractal dimensions are involved in a rather general dynamical context. We speculate that various scaling phenomena are independent of the full dynamical structure, depending only on a general stochastic framework having to do with simple maps and strange attractors. 42 references.

  13. Complete and incomplete fusion reactions in the {sup 16}O+{sup 169}Tm system: Excitation functions and recoil range distributions

    SciTech Connect

    Sharma, Manoj Kumar; Unnati,; Sharma, B.K.; Singh, B.P.; Prasad, R.; Bhardwaj, H.D.; Kumar, Rakesh; Golda, K.S.

    2004-10-01

    With the view to study complete and incomplete fusion in heavy ion induced reactions, experiments have been carried out for measuring excitation functions for several reactions in the system {sup 16}O+{sup 169}Tm at energies near the Coulomb barrier to well above it, using an activation technique. The measured excitation functions have been compared with those calculated theoretically using three different computer codes viz., ALICE-91, CASCADE and PACE2. The enhancement of experimentally measured cross sections for alpha emission channels over their theoretical prediction has been attributed to the fact that these residues are formed not only by complete fusion but also through incomplete fusion. In order to separate out the relative contributions of complete and incomplete fusion, the recoil range distributions of eight residues produced in the interaction of {sup 16}O with {sup 169}Tm at {approx_equal}87 MeV have been measured. The recoil range distributions indicate significant contributions from incomplete fusion at {approx_equal}87 MeV for some of the channels.

  14. Excitation functions of proton induced reactions on natOs up to 65 MeV: Experiments and comparison with results from theoretical codes

    NASA Astrophysics Data System (ADS)

    Hermanne, A.; Adam Rebeles, R.; Tárkányi, F.; Takács, S.

    2015-02-01

    Activation of thin natOs targets, electrodeposited on Ni backings, was investigated for the first time in stacked foil irradiations with 65 MeV and 34 MeV proton beams. Assessments of the produced radionuclides by high resolution gamma-ray spectroscopy yielded excitation functions for formation of 184, 185, 186m,m+g, 187m+g, 188m+g, 189m2+m1+g, 190m2,m1+g, 192m1+gIr and 185cum, 191m+gOs, 183m+gRe. Where available comparisons with the reaction cross sections obtained in 2 earlier studies on enriched 192Os were made. Reduced uncertainty on cross sections is obtained by simultaneous remeasurement of the 27Al(p,x)22,24Na, natNi(p,x)57Ni and natTi(p,x)48V monitor reactions over wide relevant energy ranges. Confirmation of monitoring took place by assessment of excitation functions of 61Cu, 56Ni, 55,56,57,58Co and 52Mn induced in the Ni backings and comparison with a recent compilation for most of these radionuclides. Contributing reactions and overall cross sections are discussed and were evaluated in comparison with the results of the theoretical code TALYS 1.6 (values from the on-line library TENDL-2013).

  15. Strange-Mode Instability for Micro-Variations in Luminous Blue Variables

    NASA Astrophysics Data System (ADS)

    Saio, H.; Georgy, C.; Meynet, G.

    2013-12-01

    If a massive star has lost significant mass during its red-supergiant (RSG) stage, it would return to the blue region in the Hertzsprung-Russell (HR) diagram and spend a part of the core-He burning stage as a blue supergiant having a luminosity to mass ratio (L/M) considerably larger than about 104 (in solar units); the duration depends on the degree of internal mixing and on the metallicity. Then, various stellar pulsations are excited by an enhanced κ-mechanism and strange-mode instability. Assuming these pulsations to be responsible for (at least some of) the quasi-periodic light and radial velocity variations in α Cygni variables, including luminous blue variables (LBVs; or S Dor variables), we can predict masses and surface compositions for these variables, and compare them with observation to constrain evolutionary models. We discuss radial pulsations excited in evolutionary models of an initial mass of 40 M⊙ with solar metallicity of Z = 0.014, and compare them to micro-variations in the two Galactic LBVs, HR Car and HD 160529. We have found that these stars should have lost more than half of the initial mass and their surface CNO abundances should be significantly modified from the original ones showing partial H-burning products.

  16. Excitation energies with linear response density matrix functional theory along the dissociation coordinate of an electron-pair bond in N-electron systems

    NASA Astrophysics Data System (ADS)

    van Meer, R.; Gritsenko, O. V.; Baerends, E. J.

    2014-01-01

    Time dependent density matrix functional theory in its adiabatic linear response formulation delivers exact excitation energies ωα and oscillator strengths fα for two-electron systems if extended to the so-called phase including natural orbital (PINO) theory. The Löwdin-Shull expression for the energy of two-electron systems in terms of the natural orbitals and their phases affords in this case an exact phase-including natural orbital functional (PILS), which is non-primitive (contains other than just J and K integrals). In this paper, the extension of the PILS functional to N-electron systems is investigated. With the example of an elementary primitive NO functional (BBC1) it is shown that current density matrix functional theory ground state functionals, which were designed to produce decent approximations to the total energy, fail to deliver a qualitatively correct structure of the (inverse) response function, due to essential deficiencies in the reconstruction of the two-body reduced density matrix (2RDM). We now deduce essential features of an N-electron functional from a wavefunction Ansatz: The extension of the two-electron Löwdin-Shull wavefunction to the N-electron case informs about the phase information. In this paper, applications of this extended Löwdin-Shull (ELS) functional are considered for the simplest case, ELS(1): one (dissociating) two-electron bond in the field of occupied (including core) orbitals. ELS(1) produces high quality ωα(R) curves along the bond dissociation coordinate R for the molecules LiH, Li2, and BH with the two outer valence electrons correlated. All of these results indicate that response properties are much more sensitive to deficiencies in the reconstruction of the 2RDM than the ground state energy, since derivatives of the functional with respect to both the NOs and the occupation numbers need to be accurate.

  17. Excitation energies with linear response density matrix functional theory along the dissociation coordinate of an electron-pair bond in N-electron systems

    SciTech Connect

    Meer, R. van; Gritsenko, O. V.; Baerends, E. J.

    2014-01-14

    Time dependent density matrix functional theory in its adiabatic linear response formulation delivers exact excitation energies ω{sub α} and oscillator strengths f{sub α} for two-electron systems if extended to the so-called phase including natural orbital (PINO) theory. The Löwdin-Shull expression for the energy of two-electron systems in terms of the natural orbitals and their phases affords in this case an exact phase-including natural orbital functional (PILS), which is non-primitive (contains other than just J and K integrals). In this paper, the extension of the PILS functional to N-electron systems is investigated. With the example of an elementary primitive NO functional (BBC1) it is shown that current density matrix functional theory ground state functionals, which were designed to produce decent approximations to the total energy, fail to deliver a qualitatively correct structure of the (inverse) response function, due to essential deficiencies in the reconstruction of the two-body reduced density matrix (2RDM). We now deduce essential features of an N-electron functional from a wavefunction Ansatz: The extension of the two-electron Löwdin-Shull wavefunction to the N-electron case informs about the phase information. In this paper, applications of this extended Löwdin-Shull (ELS) functional are considered for the simplest case, ELS(1): one (dissociating) two-electron bond in the field of occupied (including core) orbitals. ELS(1) produces high quality ω{sub α}(R) curves along the bond dissociation coordinate R for the molecules LiH, Li{sub 2}, and BH with the two outer valence electrons correlated. All of these results indicate that response properties are much more sensitive to deficiencies in the reconstruction of the 2RDM than the ground state energy, since derivatives of the functional with respect to both the NOs and the occupation numbers need to be accurate.

  18. Excitation energies with linear response density matrix functional theory along the dissociation coordinate of an electron-pair bond in N-electron systems.

    PubMed

    van Meer, R; Gritsenko, O V; Baerends, E J

    2014-01-14

    Time dependent density matrix functional theory in its adiabatic linear response formulation delivers exact excitation energies ωα and oscillator strengths fα for two-electron systems if extended to the so-called phase including natural orbital (PINO) theory. The Löwdin-Shull expression for the energy of two-electron systems in terms of the natural orbitals and their phases affords in this case an exact phase-including natural orbital functional (PILS), which is non-primitive (contains other than just J and K integrals). In this paper, the extension of the PILS functional to N-electron systems is investigated. With the example of an elementary primitive NO functional (BBC1) it is shown that current density matrix functional theory ground state functionals, which were designed to produce decent approximations to the total energy, fail to deliver a qualitatively correct structure of the (inverse) response function, due to essential deficiencies in the reconstruction of the two-body reduced density matrix (2RDM). We now deduce essential features of an N-electron functional from a wavefunction Ansatz: The extension of the two-electron Löwdin-Shull wavefunction to the N-electron case informs about the phase information. In this paper, applications of this extended Löwdin-Shull (ELS) functional are considered for the simplest case, ELS(1): one (dissociating) two-electron bond in the field of occupied (including core) orbitals. ELS(1) produces high quality ωα(R) curves along the bond dissociation coordinate R for the molecules LiH, Li2, and BH with the two outer valence electrons correlated. All of these results indicate that response properties are much more sensitive to deficiencies in the reconstruction of the 2RDM than the ground state energy, since derivatives of the functional with respect to both the NOs and the occupation numbers need to be accurate. PMID:24437859

  19. Parity Violating Electron Scattering and Strangeness in the Nucleon

    SciTech Connect

    Maas, Frank E.

    2008-10-13

    A measurement of the weak form factor of the proton allows a flavor separation of the strangeness contribution to the electromagnetic form factors. The weak form factor is accessed experimentally by the measurement of a parity violating (PV) asymmetry in the scattering of polarized electrons on unpolarized protons. An extended experimental program to measure these parity violating asymmetries has been performed and is going on at different accelerators. After the first round of experiments allowing a separation of the strangeness form factors G{sub E}{sup s} and G{sub M}{sup s} at a Q{sup 2}-value of 0.1 (GeV/c){sup 2}, new, preliminary results have been achieved at 0.23 (GeV/c){sup 2}.

  20. Fast pulsars, strange stars: An opportunity in radio astronomy

    SciTech Connect

    Glendenning, N.K.

    1990-07-15

    The world's data on radio pulsars is not expected to represent the underlying pulsar population because of a search bias against detection of short periods, especially below 1 ms. Yet pulsars in increasing numbers with periods right down to this limit have been discovered suggesting that there may be even shorter ones. If pulsars with periods below 1/2 ms were found, the conclusion that the confined hadronic phase of nucleons and nuclei is only metastable would be almost inescapable. The plausible ground state in that event is the deconfined phase of (3-flavor) strange-quark-matter. From the QCD energy scale this is as likely a ground state as the confined phase. We show that strange matter as the ground state is not ruled out by any known fact, and most especially not by the fact that the universe is in the confined phase. 136 refs.

  1. New results on strange form factors of the proton

    SciTech Connect

    Richard Holmes

    2000-12-12

    At the Thomas Jefferson National Accelerator Facility, we have studied the elastic scattering of polarized electrons from hydrogen. The resulting parity-violating electroweak asymmetry is sensitive to the contributions of strange quarks to the nucleon form factors at a level that is of theoretical interest. Using events at a laboratory scattering angle of 12.3{sup o} and (Q{sup 2})=0.477 GeV/c, we measure the linear combination of strange form factors (G{sup n}{sub E}) + 0.39G{sup E}{sub M}/(G{sup py}{sub M}/mu{sub p}) = 0.091+/-0.054+/-0.039, where the first error is the quadratic sum of our systematic and statistical errors and the second error is due to uncertainty in nucleon form factors.

  2. Strange attractors in weakly turbulent Couette-Taylor flow

    NASA Technical Reports Server (NTRS)

    Brandstater, A.; Swinney, Harry L.

    1987-01-01

    An experiment is conducted on the transition from quasi-periodic to weakly turbulent flow of a fluid contained between concentric cylinders with the inner cylinder rotating and the outer cylinder at rest. Power spectra, phase-space portraits, and circle maps obtained from velocity time-series data indicate that the nonperiodic behavior observed is deterministic, that is, it is described by strange attractors. Various problems that arise in computing the dimension of strange attractors constructed from experimental data are discussed and it is shown that these problems impose severe requirements on the quantity and accuracy of data necessary for determining dimensions greater than about 5. In the present experiment the attractor dimension increases from 2 at the onset of turbulence to about 4 at a Reynolds number 50-percent above the onset of turbulence.

  3. Centrifugal Force Induced Collapse of Strange Stars Into Black Holes

    NASA Astrophysics Data System (ADS)

    de Paolis, F.; Ingrosso, G.; Nucita, A. A.; Qadir, Asghar

    It has been suggested that there could be objects even more compact than neutron stars, like the so-called strange stars, P-stars, and magnetars. Strange stars are collapsed stars consisting of u, d, and s quarks. P-stars are a new class of compact stars made of u and d quarks in β-equilibrium with electrons in an Abelian chromomagnetic condensate. It has also been shown that a particle in a circular orbit around a stationary black hole is subject to a centrifugal force that turns out to be directed inwards if the particle orbit radius is between the Schwarzschild radius rs and 3rs/2. Here it is proposed that rotation of a sufficiently compact collapsed object may lead to a centrifugal force induced collapse to a black hole that could emit short gamma-ray bursts.

  4. A useful approximate isospin equality for charmless strange B decays.

    SciTech Connect

    Lipkin, H. J.; High Energy Physics; Weizmann Inst. of Science; Aviv Univ.

    1999-01-01

    A useful inequality is obtained if charmless strange B decays are assumed to be dominated by a {Delta}l=0 transition like that from the gluonic penguin diagram and the contributions of all other diagrams including the tree, electroweak penguin and annihilation diagrams are small but not negligible. The interference contributions which are linear in these other amplitudes are included but the direct contributions which are quadratic are neglected.

  5. Bulk viscosity of strange quark matter: Urca versus nonleptonic processes

    SciTech Connect

    Sa'd, Basil A.; Shovkovy, Igor A.; Rischke, Dirk H.

    2007-06-15

    A general formalism for calculating the bulk viscosity of strange quark matter is developed. Contrary to the common belief that the nonleptonic processes alone give the dominant contribution to the bulk viscosity, the inclusion of the Urca processes is shown to play an important role at intermediate densities when the characteristic r-mode oscillation frequencies are not too high. The interplay of nonleptonic and Urca processes is analyzed in detail.

  6. Strange hadron production at SIS energies: an update from HADES

    NASA Astrophysics Data System (ADS)

    Lorenz, M.; Adamczewski-Musch, J.; Arnold, O.; Atomssa, E. T.; Behnke, C.; Berger-Chen, J. C.; Biernat, J.; Blanco, A.; Blume, C.; Böhmer, M.; Bordalo, P.; Chernenko, S.; Deveaux, C.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Fonte, P.; Franco, C.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzón, J. A.; Gill, K.; Golubeva, M.; Guber, F.; Gumberidze, M.; Harabasz, S.; Hennino, T.; Hlavac, S.; Höhne, C.; Holzmann, R.; Ierusalimov, A.; Ivashkin, A.; Jurkovic, M.; Kämpfer, B.; Karavicheva, T.; Kardan, B.; Koenig, I.; Koenig, W.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kotte, R.; Krása, A.; Krebs, E.; Kuc, G.; Kugler, A.; Kunz, T.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lapidus, K.; Lebedev, A.; Lopes, L.; Mahmoud, T.; Maier, L.; Mangiarotti, A.; Markert, J.; Metag, V.; Michel, J.; Müntz, C.; Münzer, R.; Naumann, L.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Petousis, V.; Pietraszko, J.; Przygoda, W.; Ramstein, B.; Rehnisch, L.; Reshetin, A.; Rost, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schmidt-Sommerfeld, K.; Schuldes, H.; Sellheim, P.; Siebenson, J.; Silva, L.; Sobolev, Yu. G.; Spataro, S.; Ströbele, H.; Stroth, J.; Strzempek, P.; Sturm, C.; Svoboda, O.; Tarantola, A.; Teilab, K.; Tlusty, P.; Traxler, M.; Tsertos, H.; Vasiliev, T.; Wagner, V.; Wendisch, C.; Wirth, J.; Wüstenfeld, J.; Zanevsky, Y.; Zumbruch, P.

    2016-01-01

    We present and discuss recent experimental activities of the HADES collaboration on open and hidden strangeness production close or below the elementary NN threshold. Special emphasis is put on the feed-down from ϕ mesons to antikaons, the presence of the Ξ- excess in cold nuclear matter and the comparison of statistical model rates to elementary p+p data. The implications for the interpretation of heavy-ion data are discussed as well.

  7. The discrepant kinematics of recombination and collisionally-excited in NGC7009 as a function of ionization structure

    NASA Astrophysics Data System (ADS)

    Arrieta, A.; Richer, M.; Georgiev, L. N.; Torres-Peimbert, S.

    2014-04-01

    We present spatially- and velocity-resolved echelle spectroscopy for NGC 7009 obtained with the UVES spectrograph at the ESO VLT. We construct position-velocity maps for recombination, fluorescence, charge transfer, and collisionally excited lines. We find a plasma component emitting in the C II, N II, O II, and Ne II recombination lines whose kinematics are discrepant: They are incompatible with the ionization structure derived from all other evidence and the kinematics derived from all of these lines are unexpectedly very similar. We find direct evidence for a recombination contribution to [N II] 5755. Once taken into account, the electron temperatures from [N II], [O III], and [Ne III] agree at a given position and velocity, even though both the [N II] and [O III] temperatures clearly vary. The electron densities derived from [O II] and [Ar IV] are consistent with direct imaging and the distribution of hydrogen emission. The kinematics of the C II, N II, O II, and Ne II lines does not coincide with the kinematics of the [O III] and [Ne III] forbidden emission, indicating that there is an additional plasma component to the recombination emission that arises from a different volume from that giving rise to the forbidden emission from the parent ions within NGC 7009. Thus, the chemical abundances derived from either type of line are correct only for the plasma component from which they arise. Apart from [N II] 5755, we find no anomaly with the forbidden lines usually used to determine chemical abundances in ionized nebulae, so the abundances derived from them should be reliable for the medium from which they arise.

  8. Simulating One-Photon Absorption and Resonance Raman Scattering Spectra Using Analytical Excited State Energy Gradients within Time-Dependent Density Functional Theory

    SciTech Connect

    Silverstein, Daniel W.; Govind, Niranjan; van Dam, Hubertus J. J.; Jensen, Lasse

    2013-12-10

    A parallel implementation of analytical time-dependent density functional theory gradients is presented for the quantum chemistry program NWChem. The implementation is based on the Lagrangian approach developed by Furche and Ahlrichs. To validate our implementation, we first calculate the Stokes shifts for a range of organic dye molecules using a diverse set of exchange-correlation functionals (traditional density functionals, global hybrids, and range-separated hybrids) followed by simulations of the one-photon absorption and resonance Raman scattering spectrum of the phenoxyl radical, the well-studied dye molecule rhodamine 6G, and a molecular host–guest complex (TTFcCBPQT4+). The study of organic dye molecules illustrates that B3LYP and CAM-B3LYP generally give the best agreement with experimentally determined Stokes shifts unless the excited state is a charge transfer state. Absorption, resonance Raman, and fluorescence simulations for the phenoxyl radical indicate that explicit solvation may be required for accurate characterization. For the host–guest complex and rhodamine 6G, it is demonstrated that absorption spectra can be simulated in good agreement with experimental data for most exchange-correlation functionals. Finally, however, because one-photon absorption spectra generally lack well-resolved vibrational features, resonance Raman simulations are necessary to evaluate the accuracy of the exchange-correlation functional for describing a potential energy surface.

  9. Neutron stars, strange stars, and the nuclear equation of state

    SciTech Connect

    Weber, F.; Glendenning, N.K.

    1992-11-02

    This article consists of three parts. In part one we review the present status of dense nuclear matter calculations, and introduce a representative collection of realistic nuclear equations of state which are derived for different assumptions about the physical behavior of dense matter (baryon population, pion condensation,.possible transition of baryon matter to quark matter). In part two we review recently performed non-rotating and rotating compact star calculations performed for these equations of state. The minimum stable rotational periods of compact stars, whose knowledge is of decisive importance for the interpretation of rapidly rotating pulsars, axe determined. For this purpose two different limits on stable rotation are studied: rotation at the general relativistic Kepler period (below which mass shedding at the star's equator sets in), and, secondly, rotation at the gravitational radiation-reaction instability (at which emission of gravitational waves set in which slows the star down). Part three of this article deals with the properties of hypothetical strange stars. Specifically we investigate the amount of nuclear solid crust that can be carried by a rotating strange star, and answer the question whether such objects can give rise to the observed phenomena of pulsar glitches, which is at the present time the only astrophysical test of the strange-quark-matter hypothesis.

  10. Neutron stars, strange stars, and the nuclear equation of state

    SciTech Connect

    Weber, F.; Glendenning, N.K.

    1992-11-02

    This article consists of three parts. In part one we review the present status of dense nuclear matter calculations, and introduce a representative collection of realistic nuclear equations of state which are derived for different assumptions about the physical behavior of dense matter (baryon population, pion condensation,.possible transition of baryon matter to quark matter). In part two we review recently performed non-rotating and rotating compact star calculations performed for these equations of state. The minimum stable rotational periods of compact stars, whose knowledge is of decisive importance for the interpretation of rapidly rotating pulsars, axe determined. For this purpose two different limits on stable rotation are studied: rotation at the general relativistic Kepler period (below which mass shedding at the star`s equator sets in), and, secondly, rotation at the gravitational radiation-reaction instability (at which emission of gravitational waves set in which slows the star down). Part three of this article deals with the properties of hypothetical strange stars. Specifically we investigate the amount of nuclear solid crust that can be carried by a rotating strange star, and answer the question whether such objects can give rise to the observed phenomena of pulsar glitches, which is at the present time the only astrophysical test of the strange-quark-matter hypothesis.

  11. Reduced L-type Ca2+ current and compromised excitability induce loss of skeletal muscle function during acute cooling in locust.

    PubMed

    Findsen, Anders; Overgaard, Johannes; Pedersen, Thomas Holm

    2016-08-01

    Low temperature causes most insects to enter a state of neuromuscular paralysis, termed chill coma. The susceptibility of insect species to chill coma is tightly correlated to their distribution limits and for this reason it is important to understand the cellular processes that underlie chill coma. It is known that muscle function is markedly depressed at low temperature and this suggests that chill coma is partly caused by impairment in the muscle per se. To find the cellular mechanism(s) underlying muscle dysfunction at low temperature, we examined the effect of low temperature (5°C) on several events in excitation-contraction coupling in the migratory locust (Locusta migratoria). Intracellular membrane potential recordings during single nerve stimulations showed that 70% of fibers at 20°C produced an action potential (AP), while only 55% of fibers were able to fire an AP at 5°C. Reduced excitability at low temperature was caused by an ∼80% drop in L-type Ca(2+) current and a depolarizing shift in its activation of around 20 mV, which means that a larger endplate potential would be needed to activate the muscle AP at low temperature. In accordance, we showed that intracellular Ca(2+) transients were largely absent at low temperature following nerve stimulation. In contrast, maximum contractile force was unaffected by low temperature in chemically skinned muscle bundles, which demonstrates that the function of the contractile filaments is preserved at low temperature. These findings demonstrate that reduced L-type Ca(2+) current is likely to be the most important factor contributing to loss of muscle function at low temperature in locust. PMID:27247315

  12. Neutron stars and strange stars in the chiral SU(3) quark mean field model

    SciTech Connect

    P. Wang; S. Lawley; D. B. Leinweber; A. W. Thomas; A. G. Williams

    2005-06-01

    We investigate the equations of state for pure neutron matter and strange hadronic matter in {beta}-equilibrium, including {Lambda}, {Sigma} and {Xi} hyperons. The masses and radii of pure neutron stars and strange hadronic stars are obtained. For a pure neutron star, the maximum mass is about 1.8 M{sub sun}, while for a strange hadronic star, the maximum mass is around 1.45M{sub sun}. The typical radii of pure neutron stars and strange hadronic stars are about 11.0-12.3 km and 10.7-11.7 km, respectively.

  13. Assessment of density functional theory based ΔSCF (self-consistent field) and linear response methods for longest wavelength excited states of extended π-conjugated molecular systems

    SciTech Connect

    Filatov, Michael; Huix-Rotllant, Miquel

    2014-07-14

    Computational investigation of the longest wavelength excitations in a series of cyanines and linear n-acenes is undertaken with the use of standard spin-conserving linear response time-dependent density functional theory (TD-DFT) as well as its spin-flip variant and a ΔSCF method based on the ensemble DFT. The spin-conserving linear response TD-DFT fails to accurately reproduce the lowest excitation energy in these π-conjugated systems by strongly overestimating the excitation energies of cyanines and underestimating the excitation energies of n-acenes. The spin-flip TD-DFT is capable of correcting the underestimation of excitation energies of n-acenes by bringing in the non-dynamic electron correlation into the ground state; however, it does not fully correct for the overestimation of the excitation energies of cyanines, for which the non-dynamic correlation does not seem to play a role. The ensemble DFT method employed in this work is capable of correcting for the effect of missing non-dynamic correlation in the ground state of n-acenes and for the deficient description of differential correlation effects between the ground and excited states of cyanines and yields the excitation energies of both types of extended π-conjugated systems with the accuracy matching high-level ab initio multireference calculations.

  14. Excited Delirium

    PubMed Central

    Takeuchi, Asia; Ahern, Terence L.; Henderson, Sean O.

    2011-01-01

    Excited (or agitated) delirium is characterized by agitation, aggression, acute distress and sudden death, often in the pre-hospital care setting. It is typically associated with the use of drugs that alter dopamine processing, hyperthermia, and, most notably, sometimes with death of the affected person in the custody of law enforcement. Subjects typically die from cardiopulmonary arrest, although the cause is debated. Unfortunately an adequate treatment plan has yet to be established, in part due to the fact that most patients die before hospital arrival. While there is still much to be discovered about the pathophysiology and treatment, it is hoped that this extensive review will provide both police and medical personnel with the information necessary to recognize and respond appropriately to excited delirium. PMID:21691475

  15. Excited baryons

    SciTech Connect

    Mukhopadhyay, N.C.

    1986-01-01

    The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested. (LEW)

  16. Extension of excitation functions up to 50 MeV for activation products in deuteron irradiations of Pr and Tm targets

    NASA Astrophysics Data System (ADS)

    Hermanne, A.; Tárkányi, F.; Takács, S.; Ditrói, F.

    2016-09-01

    Extension up to 50 MeV incident deuteron energy is presented for excitation functions of activation products formed in monoisotopic Tm (169Tm) and Pr (141Pr). By stacked foil irradiations direct and/or cumulative production of 140,139m,138Nd, 138mPr, 141,139,137m,135Ce on Pr and 166,169Yb, 166,167,168Tm on Tm targets were measured. Confirmation of earlier experimental results for all investigated radionuclides is found and the influence of the higher energy on thick target yields and batch production of medically relevant radionuclides (140Nd, 139Pr (as decay product of 139mNd), 166,169Yb, 167Tm) is discussed. A comparison of experimental values with TALYS1.6 code results (predicted values from TENDL-2015 on-line library) shows a better description of the (d,pxn) reactions than older ones.

  17. An efficient formulation and implementation of the analytic energy gradient method to the single and double excitation coupled-cluster wave function - Application to Cl2O2

    NASA Technical Reports Server (NTRS)

    Rendell, Alistair P.; Lee, Timothy J.

    1991-01-01

    The analytic energy gradient for the single and double excitation coupled-cluster (CCSD) wave function has been reformulated and implemented in a new set of programs. The reformulated set of gradient equations have a smaller computational cost than any previously published. The iterative solution of the linear equations and the construction of the effective density matrices are fully vectorized, being based on matrix multiplications. The new method has been used to investigate the Cl2O2 molecule, which has recently been postulated as an important intermediate in the destruction of ozone in the stratosphere. In addition to reporting computational timings, the CCSD equilibrium geometries, harmonic vibrational frequencies, infrared intensities, and relative energetics of three isomers of Cl2O2 are presented.

  18. Time-dependent density functional theory (TDDFT) study of the excited charge-transfer state formation of a series of aromatic donor-acceptor systems.

    PubMed

    Jamorski Jödicke, Christine; Lüthi, Hans Peter

    2003-01-01

    Singlet excitation energy calculations for a series of acceptor para-substituted N,N-dimethyl-anilines that are dual (4-(N,N-dimethylamino)benzonitrile, 4DMAB-CN, 4-(N,N-dimethylamino)benzaldhyde, 4DMAB-CHO, 1-methyl-7-cyano-2,3,4,5-tetrahydro-1H-1-benzazepine, NMC7) and nondual (4-aminobenzonitrile, 4AB-CN, 3-(N,N-dimethylamino)benzonitrile, 3DMAB-CN, and 4-nitro(N,N-dimethyl) aniline, 4DMAB-NO(2)) fluorescent have been performed using time-dependent density functional theory (TDDFT). The B3LYP and MPW1PW91 functionals with a 6-311+G(2d,p) (Bg) basis set have been used to compute excitation energies. Ground-state geometries were optimized using density functional theory (DFT) with both B3LYP and MPW1PW91 functionals combined with a 6-31G(d) basis set. For most of the molecules presented in this study, potential energy surfaces have been computed according to the coordinates related to the three following mechanisms proposed in the literature: twisting, wagging, and planar intramolecular charge transfer (ICT). Comparison of the three models for the different molecules leads to the conclusion that only the twisting ICT model is able to explain the low frequency, strongly solvent-dependent energy band present in the fluorescence spectra. According to this model, the 4AB-CN molecule is calculated to be nondual fluorescent in agreement with the experimental spectra. The single band observed in the fluorescence spectra of TMAB-CN (4-(N,N-dimethylamino)-3,5-(dimethyl)benzonitrile) is due to a large stabilization of the charge-transfer excited state along the twisting coordinate. The nondual fluorescence of the 4DMAB-NO(2) molecule is explained by the same mechanism. In the case of 3DMAB-CN, the single observed emission, which is solvent-dependent, has been assigned to the lowest charge-transfer excited state. The dual fluorescence of 4DMAB-CN and 4DMAB-CHO is explained within the twisting ICT model by a double mechanism (already proposed by Serrano et al.: Serrano

  19. Excitation functions for production of heavy actinides from interactions of /sup 18/O with /sup 248/Cm and /sup 249/Cf

    SciTech Connect

    Lee, D.; Moody, K.J.; Nurmia, M.J.; Seaborg, G.T.; von Gunten, H.R.; Hoffman, D.C.

    1983-06-01

    Excitation functions have been measured for the production of isotopes of Bk through Fm in bombardments of /sup 248/Cm with 97- to 122-MeV /sup 18/O ions and of isotopes of Bk through No in bombardments of /sup 249/Cf with 91- to 150-MeV /sup 18/O ions. The cross sections and widths of the mass distributions for the actinides produced in these reactions are very similar for transfer of the same numbers of nucleons. A semiquantitative comparison of the experimental results with calculations based on a simple model shows that calculations of this type are helpful in selection of projectile-target systems and optimum energies for production of specific actinide isotopes and for synthesis of as yet unknown heavy isotopes and elements. Comparisons of experimental results with calculations show that, in general, about half of the kinetic energy of the projectile is transferred to the actinide product.

  20. Excitation functions of deuteron induced reactions on natOs up to 50 MeV: Experiments and comparison with theoretical codes

    NASA Astrophysics Data System (ADS)

    Hermanne, A.; Adam Rebeles, R.; Tárkányi, F.; Takács, S.; Takács, M. P.; Ignatyuk, A.; Uddin, M. S.

    2013-02-01

    Activation of thin electrodeposited natural Os targets was investigated in a stacked foil irradiation with a 50 MeV deuteron beam. Assessments of the produced radionuclides by high resolution gamma spectroscopy yielded excitation functions for production of 184,185,186m1,g,187m1+g,188m1+g,189m2+m1+g,190m2,190m2,m1+g,192m1+gIr and 185Os. Reduced uncertainty on cross sections is obtained by simultaneous remeasurement of the 27Al(d,x)24Na monitor reaction over the whole energy range. Thick target yield for deuteron induced production route of 192m1+gIr and comparison with the natIr(n,γ) route are reviewed. A comparison with updated theoretical codes (ALICE-D, EMPIRE-D and the TENDL2011 on-line library) is discussed.

  1. Knockout of the BK β4-subunit promotes a functional coupling of BK channels and ryanodine receptors that mediate a fAHP-induced increase in excitability.

    PubMed

    Wang, Bin; Bugay, Vladislav; Ling, Ling; Chuang, Hui-Hsui; Jaffe, David B; Brenner, Robert

    2016-08-01

    BK channels are large-conductance calcium- and voltage-activated potassium channels with diverse properties. Knockout of the accessory BK β4-subunit in hippocampus dentate gyrus granule neurons causes BK channels to change properties from slow-gated type II channels to fast-gated type I channels that sharpen the action potential, increase the fast afterhyperpolarization (fAHP) amplitude, and increase spike frequency. Here we studied the calcium channels that contribute to fast-gated BK channel activation and increased excitability of β4 knockout neurons. By using pharmacological blockers during current-clamp recording, we find that BK channel activation during the fAHP is dependent on ryanodine receptor activation. In contrast, L-type calcium channel blocker (nifedipine) affects the BK channel-dependent repolarization phase of the action potential but has no effect on the fAHP. Reducing BK channel activation during the repolarization phase with nifedipine, or during the fAHP with ryanodine, indicated that it is the BK-mediated increase of the fAHP that confers proexcitatory effects. The proexcitatory role of the fAHP was corroborated using dynamic current clamp. Increase or decrease of the fAHP amplitude during spiking revealed an inverse relationship between fAHP amplitude and interspike interval. Finally, we show that the seizure-prone ryanodine receptor gain-of-function (R2474S) knockin mice have an unaltered repolarization phase but larger fAHP and increased AP frequency compared with their control littermates. In summary, these results indicate that an important role of the β4-subunit is to reduce ryanodine receptor-BK channel functional coupling during the fAHP component of the action potential, thereby decreasing excitability of dentate gyrus neurons. PMID:27146987

  2. Investigating strangeness in the proton by studying the effects of Light Cone parton distributions in the Meson Cloud Model

    NASA Astrophysics Data System (ADS)

    Tuppan, Sam; Budnik, Garrett; Fox, Jordan

    2014-09-01

    The Meson Cloud Model (MCM) has proven to be a natural explanation for strangeness in the proton because of meson-baryon splitting into kaon-hyperon pairs. Total strangeness is predicted by integrated splitting functions, which represent the probability that the proton will fluctuate into a given meson-baryon pair. However, the momentum distributions s (x) and s (x) in the proton are determined from convolution integrals that depend on the parton distribution functions (PDFs) used for the mesons and baryons in the MCM. Theoretical calculations of these momentum distributions use many different forms for these PDFs. In our investigation, we calculate PDFs for K, K*, Λ, and Σ from two-body wave functions in a Light Cone Model (LCM) of the hadrons. We use these PDFs in conjunction with the MCM to create a hybrid model and compare our results to other theoretical calculations, experimental data from NuTeV, HERMES, ATLAS, and global parton distribution analyses. The Meson Cloud Model (MCM) has proven to be a natural explanation for strangeness in the proton because of meson-baryon splitting into kaon-hyperon pairs. Total strangeness is predicted by integrated splitting functions, which represent the probability that the proton will fluctuate into a given meson-baryon pair. However, the momentum distributions s (x) and s (x) in the proton are determined from convolution integrals that depend on the parton distribution functions (PDFs) used for the mesons and baryons in the MCM. Theoretical calculations of these momentum distributions use many different forms for these PDFs. In our investigation, we calculate PDFs for K, K*, Λ, and Σ from two-body wave functions in a Light Cone Model (LCM) of the hadrons. We use these PDFs in conjunction with the MCM to create a hybrid model and compare our results to other theoretical calculations, experimental data from NuTeV, HERMES, ATLAS, and global parton distribution analyses. This research has been supported in part by the

  3. Discriminating strange star mergers from neutron star mergers by gravitational-wave measurements

    SciTech Connect

    Bauswein, A.; Oechslin, R.; Janka, H.-T.

    2010-01-15

    We perform three-dimensional relativistic hydrodynamical simulations of the coalescence of strange stars and explore the possibility to decide on the strange matter hypothesis by means of gravitational-wave measurements. Self-binding of strange quark matter and the generally more compact stars yield features that clearly distinguish strange star from neutron star mergers, e.g. hampering tidal disruption during the plunge of quark stars. Furthermore, instead of forming dilute halo structures around the remnant as in the case of neutron star mergers, the coalescence of strange stars results in a differentially rotating hypermassive object with a sharp surface layer surrounded by a geometrically thin, clumpy high-density strange quark matter disk. We also investigate the importance of including nonzero temperature equations of state in neutron star and strange star merger simulations. In both cases we find a crucial sensitivity of the dynamics and outcome of the coalescence to thermal effects, e.g. the outer remnant structure and the delay time of the dense remnant core to black hole collapse depend on the inclusion of nonzero temperature effects. For comparing and classifying the gravitational-wave signals, we use a number of characteristic quantities like the maximum frequency during inspiral or the dominant frequency of oscillations of the postmerger remnant. In general, these frequencies are higher for strange star mergers. Only for particular choices of the equation of state the frequencies of neutron star and strange star mergers are similar. In such cases additional features of the gravitational-wave luminosity spectrum like the ratio of energy emitted during the inspiral phase to the energy radiated away in the postmerger stage may help to discriminate coalescence events of the different types. If such characteristic quantities could be extracted from gravitational-wave signals, for instance with the upcoming gravitational-wave detectors, a decision on the

  4. Zn-phthalocyanine-functionalized nanometal and nanometal-TiO₂ hybrids: aggregation behavior and excited-state dynamics.

    PubMed

    Ashokkumar, R; Kathiravan, A; Ramamurthy, P

    2014-07-21

    Dithiol-substituted Zn-phthalocyanine derivatives (TAZnPc1, TAZnPc2 and TAZnPc3) were synthesized and functionalized on nanometals (Au and Ag) and nanometal-TiO2 hybrids were harnessed to cover the visible region of the absorption spectrum. Photophysical studies reveal that both H- and J-aggregation were present in the ZnPc-functionalized nanometal, and the extent of J-aggregation is superior on the surface of Ag nanoparticles. On the other hand, no H-aggregation was observed in the nanometal-TiO2 hybrid film, despite the fact that the tetra-anchoring derivative (TAZnPc3) shows lesser J-aggregation on the nanometal-TiO2 hybrid film than that of other two mono-anchoring derivatives (TAZnPc1 and TAZnPc2). Further, the electron injection and recombination processes were investigated by time-resolved fluorescence and absorption spectroscopy. All the derivatives furnish biexponential decay on the nanometal surface. The shorter component is due to electron injection of ZnPc-nanometal particles and the longer component is due to free ZnPc. The rate of electron injection is faster for ZnPc-gold nanoparticles than that of silver nanoparticles, predominantly in TAZnPc1. This is due to the greater aggregation tendency of ZnPc derivatives on Ag nanoparticles than Au nanoparticles. After electron injection, the electron-transfer product (i.e. the radical cation of ZnPc) was observed at 600 nm. Moreover, the fluorescence of ZnPc derivatives on nanometal-TiO2 films was completely quenched due to the shuttling of electrons from ZnPc to TiO2 efficiently by metal nanoparticles. PMID:24902514

  5. High-School Student Discovers Strange Astronomical Object

    NASA Astrophysics Data System (ADS)

    2009-09-01

    A West Virginia high-school student analyzing data from a giant radio telescope has discovered a new astronomical object -- a strange type of neutron star called a rotating radio transient. Lucas Bolyard, a sophomore at South Harrison High School in Clarksburg, WV, made the discovery while participating in a project in which students are trained to scrutinize data from the National Science Foundation's giant Robert C. Byrd Green The project, called the Pulsar Search Collaboratory (PSC), is a joint project of the National Radio Astronomy Observatory (NRAO) and West Virginia University (WVU), funded by a grant from the National Science Foundation. Bolyard made the discovery in March, after he already had studied more than 2,000 data plots from the GBT and found nothing. "I was home on a weekend and had nothing to do, so I decided to look at some more plots from the GBT," he said. "I saw a plot with a pulse, but there was a lot of radio interference, too. The pulse almost got dismissed as interference," he added. Nonetheless, he reported it, and it went on a list of candidates for West Virginia University astronomers Maura McLaughlin and Duncan Lorimer to re-examine, scheduling new observations of the region of sky from which the pulse came. Disappointingly, the follow-up observations showed nothing, indicating that the object was not a normal pulsar. However, the astronomers explained to Bolyard that his pulse still might have come from a rotating radio transient. Confirmation didn't come until July. Bolyard was at the NRAO's Green Bank Observatory with fellow PSC students. The night before, the group had been observing with the GBT in the wee hours, and all were very tired. Then Lorimer showed Bolyard a new plot of his pulse, reprocessed from raw data, indicating that it is real, not interference, and that Bolyard is likely the discoverer of one of only about 30 rotating radio transients known. Suddenly, Bolyard said, he wasn't tired anymore. "That news made me full

  6. Pion- and strangeness-baryon σ terms in the extended chiral constituent quark model

    NASA Astrophysics Data System (ADS)

    An, C. S.; Saghai, B.

    2015-07-01

    Within an extended chiral constituent quark formalism, we investigate contributions from all possible five-quark components in the octet baryons to the pion-baryon (σπ B) and strangeness-baryon (σs B) sigma terms: B ≡N ,Λ ,Σ ,Ξ . The probabilities of the quark-antiquark components in the ground-state baryon octet wave functions are calculated by taking the baryons to be admixtures of three- and five-quark components, with the relevant transitions handled via the 3P0 mechanism. Predictions for σπ B and σs B obtained by using input parameters taken from the literature are reported. Our results turn out to be, in general, consistent with the findings via lattice QCD and chiral perturbation theory.

  7. A Description of the 64-meter Antenna Elevation Drive Gears and Their Strange Wear

    NASA Technical Reports Server (NTRS)

    Mcginness, H. D.

    1985-01-01

    The Deep Space Station (DSS) 64-m antenna elevation axis drive is executed by torquing two bull gears, concentric to the elevation axis, with the output pinions of four gear boxes. These gear boxes have functioned well during the 18 and 11 years, respectively, that the DSS 14, and the DSS 43 and DSS 63 antennas have been in service. A strange wear pattern gradually developed on the bull gears and driving pinions of all three antennas. These patterns were well developed after 8 years and apparently are intensifying in all instances. The elevation drive gears are described and their wear is compared to the wear of other antenna drive gears. The comparison is perplexing and satisfying explanations have not yet been made.

  8. A Functional Threshold for Long-Term Use of Hand and Arm Function Can Be Determined: Predictions From a Computational Model and Supporting Data From the Extremity Constraint-Induced Therapy Evaluation (EXCITE) Trial

    PubMed Central

    Han, Cheol E.; Wolf, Steven L.; Arbib, Michael A.; Winstein, Carolee J.

    2009-01-01

    Background Although spontaneous use of the more-affected arm and hand after stroke is an important determinant of participation and quality of life, a number of patients exhibit decreases in use following rehabilitative therapy. A previous neurocomputational model predicted that if the dose of therapy is sufficient to bring performance above a certain threshold, training can be stopped. Objective The aim of this study was to test the hypothesis that there exists a threshold for function of the paretic arm and hand after therapy. If function is above this threshold, spontaneous use will increase in the months following therapy. In contrast, if function is below this threshold, spontaneous use will decrease. Methods New computer simulations are presented showing that changes in arm use following therapy depend on a performance threshold. This prediction was tested by reanalyzing the data from the Extremity Constraint-Induced Therapy Evaluation (EXCITE) trial, a phase III randomized controlled trial in which participants received constraint-induced movement therapy for 2 weeks and were tested both 1 week and 1 year after therapy. Results The results demonstrate that arm and hand function measured immediately after therapy predicts, on average, the long-term change of arm use. Above a functional threshold, use improves. Below this threshold, use decreases. Limitations The reanalysis of the EXCITE trial data provides a “group” threshold above which a majority of patients, but not all, improve spontaneously. A goal of future research is to provide the means to assess when patients reach their individual threshold. Conclusion Understanding of the causal and nonlinear relationship between limb function and daily use is important for the future development of cost-effective interventions and prevention of “rehabilitation in vain.” PMID:19797304

  9. Measurements of Excitation Functions and Line Polarizations for Electron Impact Excitation of the n = 2, 3 States of Atomic Hydrogen in the Energy Range 11 - 2000 eV

    NASA Technical Reports Server (NTRS)

    James, G. K.; Ajello, J. M.; Kanik, I.; Slevin, J.; Franklin, B.; Shemansky, D.

    1993-01-01

    The electron-atomic hydrogen scattering system is an important testing ground for theoretical models and has received a great deal of attention from experimentalists and theoreticians alike over the years. A complete description of the excitation process requires a knowledge of many different parameters, and experimental measurements of these parameters have been performed in various laboratories around the world. As far as total cross section data are concerned it has been noted that the discrepancy between the data of Long et al. and Williams for n = 2 excitations needs to be resolved in the interests of any further refinement of theory. We report new measurements of total cross sections and atomic line polarizations for both n=2 and n=3 excitations at energies from threshold to 2000 eV...

  10. The photoproduction of strange mesons in γ p → ΛK+π+π- with CLAS at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Ghoul, Hussein Al

    2016-05-01

    The γ p → ΛK+π+π- reaction provides an opportunity to study the photoproduction of excited strange mesons in the K+π+π- system using the g12 experiment dataset at Jefferson Lab. The g12 experiment used the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab with a liquid hydrogen target and a 4 - 5.5 GeV tagged photon beam, producing over 26 billion events of different topologies. The Λ in this reaction is identified via the pπ- decay mode. Studies indicate two dominating decay modes in the K+π+π- system: the K*π+ mode and the K+ρ mode. Studies of the angular distributions and dynamical features were performed. Preliminary results of features of the data are presented.

  11. Multi-strange baryon production in psbnd Pb collisions at √{sNN} = 5.02 TeV

    NASA Astrophysics Data System (ADS)

    Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmad, S.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Almaraz, J. R. M.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Arnaldi, R.; Arnold, O. W.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Balasubramanian, S.; Baldisseri, A.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Benacek, P.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biro, G.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blair, J. T.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botta, E.; Bourjau, C.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Ceballos Sanchez, C.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chauvin, A.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Cho, S.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; De, S.; De Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; De Falco, A.; De Gruttola, D.; De Marco, N.; De Pasquale, S.; Deisting, A.; Deloff, A.; Dénes, E.; Deplano, C.; Dhankher, P.; Di Bari, D.; Di Mauro, A.; Di Nezza, P.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Drozhzhova, T.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Endress, E.; Engel, H.; Epple, E.; Erazmus, B.; Erdemir, I.; Erhardt, F.; Espagnon, B.; Estienne, M.; Esumi, S.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fronze, G. G.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Gauger, E. F.; Germain, M.; Gheata, A.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; Gonzalez, V.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Grachov, O. A.; Graczykowski, L. K.; Graham, K. L.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gronefeld, J. M.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.

    2016-07-01

    The multi-strange baryon yields in Pbsbnd Pb collisions have been shown to exhibit an enhancement relative to pp reactions. In this work, Ξ and Ω production rates have been measured with the ALICE experiment as a function of transverse momentum, pT, in psbnd Pb collisions at a centre-of-mass energy of √{sNN} = 5.02 TeV. The results cover the kinematic ranges 0.6 GeV / c strange baryons have been identified by reconstructing their weak decays into charged particles. The pT spectra are analysed as a function of event charged-particle multiplicity, which in psbnd Pb collisions ranges over one order of magnitude and lies between those observed in pp and Pbsbnd Pb collisions. The measured pT distributions are compared to the expectations from a Blast-Wave model. The parameters which describe the production of lighter hadron species also describe the hyperon spectra in high multiplicity psbnd Pb collisions. The yield of hyperons relative to charged pions is studied and compared with results from pp and Pbsbnd Pb collisions. A continuous increase in the yield ratios as a function of multiplicity is observed in psbnd Pb data, the values of which range from those measured in minimum bias pp to the ones in Pbsbnd Pb collisions. A statistical model qualitatively describes this multiplicity dependence using a canonical suppression mechanism, in which the small volume causes a relative reduction of hadron production dependent on the strangeness content of the hyperon.

  12. Aspects of strangeness production with 15 -- 30 GeV proton beams

    SciTech Connect

    Dover, C.B.

    1992-04-01

    We discuss the spectrum of physics questions related to strangeness which could be addressed with a 15--30 GeV proton storage ring. We focus on various aspects of strangeness production, including hyperon production in pp collisions, studies of hyperon-nucleon scattering, production of hyper-fragments in p-nucleus collisions, and hyperon spin observables in inclusive production.

  13. In Medium Properties of Charmed Strange Mesons in Dense Hadron ic Matter

    NASA Astrophysics Data System (ADS)

    Kumar, Sushil

    2015-05-01

    The medium modifications of the charmed strange mesons in the dense hadronic matter are investigated within chiral S U(4) model. The charmed strange meson properties modifies due to their interactions with the nucleons, hyperons and the scalar mesons (scalar-isoscalar mesons ( σ, ζ), scalar isovector meson ( δ)) in the dense hadronic medium. The various parameters used in the chiral model are obtained by fitting the vacuum baryon masses and saturation properties of nuclear matter. The non-linear coupled equations of the scalar fields are solved to obtain their baryon density, isospin and strangeness dependent values. Furthermore, the dispersion relations are derived for charmed strange mesons. Effects of isospin asymmetry and strangeness on the energies of charmed strange mesons are investigated. The in medium properties of charmed strange mesons can be particularly relevant to the experiments with neutron rich beams at the Facility for Antiproton and Ion Research (FAIR) at GSI, Germany, as well as to experiments at the Rare Isotope Accelerator (RIA) laboratory, USA. The present study of the in medium properties of charmed strange mesons will be of direct relevance for the observables from the compressed baryonic matter, resulting from the heavy ion collision experiments.

  14. Tunable Excited-State Properties and Dynamics as a Function of Pt-Pt Distance in Pyrazolate-Bridged Pt(II) Dimers.

    PubMed

    Brown-Xu, Samantha E; Kelley, Matthew S J; Fransted, Kelly A; Chakraborty, Arnab; Schatz, George C; Castellano, Felix N; Chen, Lin X

    2016-02-01

    The influence of molecular structure on excited-state properties and dynamics of a series of cyclometalated platinum dimers was investigated through a combined experimental and theoretical approach using femtosecond transient absorption (fs TA) spectroscopy and density functional theory (DFT) calculations. The molecules have the general formula [Pt(ppy)(μ-R2pz)]2, where ppy = 2-phenylpyridine, pz = pyrazolate, and R = H, Me, Ph, or (t)Bu, and are strongly photoluminescent at room temperature. The distance between the platinum centers in this A-frame geometry can be varied depending on the steric bulk of the bridging pyrazolate ligands that exert structural constraints and compress the Pt-Pt distance. At large Pt-Pt distances there is little interaction between the subunits, and the chromophore behaves similar to a monomer with excited states described as mixtures of ligand-centered and metal-to-ligand charge transfer (LC/MLCT) transitions. When the Pt(II) centers are brought closer together with bulky bridging ligands, they interact through their dz(2) orbitals and the S1 and T1 states are best characterized as metal-metal-to-ligand charge transfer (MMLCT) in character. The results of the femtoseconds TA experiments reveal that intersystem crossing (ISC) occurs on ultrafast time scales (τS1 < 200 fs), while there are two relaxation processes occurring within the triplet manifold, τ1 = 0.5-3.2 ps and τ2 = 20-70 ps; the longer time constants correspond to the presence of bulkier bridging ligands. DFT calculations illustrate that the Pt-Pt distances further contract in the T1 (3)MMLCT states; therefore, slower relaxation may be related to a larger structural reorganization. Subsequent investigations using faster time resolution are planned to measure the ISC process as well as to identify any potential coherent interaction(s) between the platinum centers that may occur. PMID:26759897

  15. Cerebellar Cortex Granular Layer Interneurons in the Macaque Monkey Are Functionally Driven by Mossy Fiber Pathways through Net Excitation or Inhibition

    PubMed Central

    Laurens, Jean; Heiney, Shane A.; Kim, Gyutae; Blazquez, Pablo M.

    2013-01-01

    The granular layer is the input layer of the cerebellar cortex. It receives information through mossy fibers, which contact local granular layer interneurons (GLIs) and granular layer output neurons (granule cells). GLIs provide one of the first signal processing stages in the cerebellar cortex by exciting or inhibiting granule cells. Despite the importance of this early processing stage for later cerebellar computations, the responses of GLIs and the functional connections of mossy fibers with GLIs in awake animals are poorly understood. Here, we recorded GLIs and mossy fibers in the macaque ventral-paraflocculus (VPFL) during oculomotor tasks, providing the first full inventory of GLI responses in the VPFL of awake primates. We found that while mossy fiber responses are characterized by a linear monotonic relationship between firing rate and eye position, GLIs show complex response profiles characterized by “eye position fields” and single or double directional tunings. For the majority of GLIs, prominent features of their responses can be explained by assuming that a single GLI receives inputs from mossy fibers with similar or opposite directional preferences, and that these mossy fiber inputs influence GLI discharge through net excitatory or inhibitory pathways. Importantly, GLIs receiving mossy fiber inputs through these putative excitatory and inhibitory pathways show different firing properties, suggesting that they indeed correspond to two distinct classes of interneurons. We propose a new interpretation of the information flow through the cerebellar cortex granular layer, in which mossy fiber input patterns drive the responses of GLIs not only through excitatory but also through net inhibitory pathways, and that excited and inhibited GLIs can be identified based on their responses and their intrinsic properties. PMID:24376524

  16. Precise Determination of the Strangeness Magnetic Moment of the Nucleon

    SciTech Connect

    Leinweber, D B; Boinepalli, S; Cloet, I C; Thomas, A W; Williams, A G; Young, R D; Zanotti, J M; Zhang, J B

    2005-06-01

    By combining the constraints of charge symmetry with new chiral extrapolation techniques and recent low mass lattice QCD simulations of the individual quark contributions to the magnetic moments of the nucleon octet, we obtain a precise determination of the strange magnetic moment of the proton. The result, namely G{sub M}{sup s} = -0.051 +/- 0.021 mu{sub N}, is consistent with the latest experimental measurements but an order of magnitude more precise. This poses a tremendous challenge for future experiments.

  17. Weak production of strange particles off the nucleon

    SciTech Connect

    Alam, M. Rafi; Athar, M. Sajjad; Simo, I. Ruiz; Alvarez-Ruso, L.; Vacas, M. J. Vicente

    2015-05-15

    The strange particle production off the nucleon induced by neutrinos and antineutrinos is investigated at low and intermediate energies. We develop a microscopic model based on the SU(3) chiral Lagrangian. The studied mechanisms are the main source of single kaon production for (anti)neutrino energies up to 1.5 GeV. Using this model we have also studied the associated production of kaons and hyperons. The cross sections are large enough to be measured by experiments such as MINERνA, T2K and NOνA.

  18. Some statistical properties of strange attractors: engineering view

    NASA Astrophysics Data System (ADS)

    Mijangos, M.; Kontorovich, V.; Aguilar-Torrentera, J.

    2008-02-01

    In this paper, the statistical characterization of strange attractors is investigated via the so-called 'model distribution' approach. It is shown that in order to calculate the first four cumulants, which are necessary to create a model distribution of kurtosis approximation, a systematic method for the calculus of the variance needs to be considered. Correspondently, an analytical method based on the Kolmogorov-Sinai (K-S) entropy for variance approximation is herein proposed. The methodology is of interest for its application in the statistical analysis of chaotic systems that model physical phenomena found in some areas of electrical (communication) engineering.

  19. Precise Determination of the Strangeness Magnetic Moment of the Nucleon

    SciTech Connect

    Leinweber, D.B.; Boinepalli, S.; Cloet, I.C.; Williams, A.G.; Young, R.D.; Zhang, J.B.; Thomas, A.W.; Zanotti, J.M.

    2005-06-03

    By combining the constraints of charge symmetry with new chiral extrapolation techniques and recent low mass quenched lattice-QCD simulations of the individual quark contributions to the magnetic moments of the nucleon octet, we obtain a precise determination of the strange magnetic moment of the proton. The result, namely, G{sub M}{sup s}=(-0.046{+-}0.019){mu}{sub N} is consistent with the latest experimental measurements but an order of magnitude more precise. This poses a tremendous challenge for future experiments.

  20. Strange-particle production via the weak interaction

    SciTech Connect

    Adera, G. B.; Van Der Ventel, B. I. S.; Niekerk, D. D. van; Mart, T.

    2010-08-15

    The differential cross sections for the neutrino-induced weak charged current production of strange particles in the threshold energy region are presented. The general representation of the weak hadronic current is newly developed in terms of eighteen unknown invariant amplitudes to parametrize the hadron vertex. The Born-term approximation is used for the numerical calculations in the framework of the Cabibbo theory and SU(3) symmetry. For unpolarized octet baryons four processes are investigated, whereas in the case of polarized baryons only one process is chosen to study the sensitivity of the differential cross section to the various polarizations of the initial-state nucleon and the final-state hyperon.

  1. Sensitive dependence to parameters, fat fractals, and universal strange attractors

    SciTech Connect

    Farmer, J.D.

    1984-03-01

    There are many nonlinear differential equations for which two different types of behavior, such as chaos and periodicity, are interwoven in a complex and intricate manner, so that the bifurcation parameters form a ''fat fractal''. The result is that statistical averages vary wildly with parameters and, strictly speaking, prediction becomes impossible even in the statistical sense. (For example, climate, as well as weather, is unpredictable.) There is, however, order in this unpredictable behavior, which can be described by a universal strange attractor of the renormalization transformation.

  2. Sensitive dependence to parameters, fat fractals, and universal strange attractors

    SciTech Connect

    Farmer, J.D.

    1984-05-01

    There are many nonlinear differential equations for which two different types of behavior, such as chaos and periodicity, are interwoven in a complex and intricate manner, so that the bifurcation parameters form a fat fractal. The result is that statistical averages vary wildly with parameters and, strictly speaking, prediction becomes impossible even in the statistical sense. (For example, climate, as well as weather, is unpredictable). There is, however, order in this unpredictable behavior, which can be described by a universal strange attractor of the renormalization transformation.

  3. Exact baryon, strangeness, and charge conservation in hadronic gas models

    SciTech Connect

    Cleymans, J.; Marais, M.; Suhonen, E.

    1997-11-01

    Relativistic heavy ion collisions are studied assuming that particles can be described by a hadron gas in thermal and chemical equilibrium. The exact conservation of baryon number, strangeness, and charge is explicitly taken into account. For heavy ions the effect arising from the neutron surplus becomes important and leads to a substantial increase in, e.g., the {pi}{sup {minus}}/{pi}{sup +} ratio. A method is developed which is suited to the study of small systems up to baryon number 20, which, unfortunately excludes cases like S-S. {copyright} {ital 1997} {ital The American Physical Society}

  4. Strangeness suppression of qq creation observed in exclusive reactions.

    PubMed

    Mestayer, M D; Park, K; Adhikari, K P; Aghasyan, M; Pereira, S Anefalos; Ball, J; Battaglieri, M; Batourine, V; Bedlinskiy, I; Biselli, A S; Boiarinov, S; Briscoe, W J; Brooks, W K; Burkert, V D; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Colaneri, L; Cole, P L; Contalbrigo, M; Cortes, O; Crede, V; D'Angelo, A; Dashyan, N; De Vita, R; Deur, A; Djalali, C; Doughty, D; Dupre, R; El Alaoui, A; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fleming, J A; Forest, T A; Garillon, B; Garçon, M; Ghandilyan, Y; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Golovatch, E; Gothe, R W; Griffioen, K A; Guegan, B; Guidal, M; Hakobyan, H; Hanretty, C; Hattawy, M; Holtrop, M; Hughes, S M; Hyde, C E; Ilieva, Y; Ireland, D G; Jiang, H; Jo, H S; Joo, K; Keller, D; Khandaker, M; Kim, A; Kim, W; Koirala, S; Kubarovsky, V; Kuleshov, S V; Lenisa, P; Levine, W I; Livingston, K; Lu, H Y; MacGregor, I J D; Mayer, M; McKinnon, B; Meyer, C A; Mirazita, M; Mokeev, V; Montgomery, R A; Moody, C I; Moutarde, H; Movsisyan, A; Camacho, C Munoz; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Pappalardo, L L; Paremuzyan, R; Peng, P; Phelps, W; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Protopopescu, D; Puckett, A J R; Raue, B A; Rimal, D; Ripani, M; Rizzo, A; Rosner, G; Roy, P; Sabatié, F; Saini, M S; Schott, D; Schumacher, R A; Simonyan, A; Sokhan, D; Strauch, S; Sytnik, V; Tang, W; Tian, Ye; Ungaro, M; Vernarsky, B; Vlassov, A V; Voskanyan, H; Voutier, E; Walford, N K; Watts, D P; Wei, X; Weinstein, L B; Wood, M H; Zachariou, N; Zhang, J; Zhao, Z W; Zonta, I

    2014-10-10

    We measured the ratios of electroproduction cross sections from a proton target for three exclusive meson-baryon final states: ΛK(+), pπ(0), and nπ(+), with the CLAS detector at Jefferson Lab. Using a simple model of quark hadronization, we extract qq creation probabilities for the first time in exclusive two-body production, in which only a single qq pair is created. We observe a sizable suppression of strange quark-antiquark pairs compared to nonstrange pairs, similar to that seen in high-energy production. PMID:25375706

  5. Electronic states of thiophene/phenylene co-oligomers: Extreme-ultra violet excited photoelectron spectroscopy observations and density functional theory calculations

    NASA Astrophysics Data System (ADS)

    Kawaguchi, Yoshizo; Sasaki, Fumio; Mochizuki, Hiroyuki; Ishitsuka, Tomoaki; Tomie, Toshihisa; Ootsuka, Teruhisa; Watanabe, Shuji; Shimoi, Yukihiro; Yamao, Takeshi; Hotta, Shu

    2013-02-01

    We have investigated electronic states in the valence electron bands for the thin films of three thiophene/phenylene co-oligomer (TPCO) compounds, 2,5-bis(4-biphenylyl)thiophene (BP1T), 1,4-bis(5-phenylthiophen-2-yl)benzene (AC5), and 1,4-bis{5-[4-(trifluoromethyl)phenyl]thiophen-2-yl}benzene (AC5-CF3), by using extreme-UV excited photoelectron spectroscopy (EUPS). By comparing both EUPS spectra and secondary electron spectra between AC5 and AC5-CF3, we confirm that CF3 substitution to AC5 deepens valence states by 2 eV, and increases the ionization energy by 3 eV. From the cut-off positions of secondary electron spectra, the work functions of AC5, AC5-CF3, and BP1T are evaluated to be 3.8 eV, 4.8 eV, and 4.0 eV, respectively. We calculate molecular orbital (MO) energy levels by the density functional theory and compare results of calculations with those of experiments. Densities of states obtained by broadening MO levels well explain the overall features of experimental EUPS spectra of three TPCOs.

  6. Two-axis acceleration of functional connectivity magnetic resonance imaging by parallel excitation of phase-tagged slices and half k-space acceleration.

    PubMed

    Jesmanowicz, Andrzej; Nencka, Andrew S; Li, Shi-Jiang; Hyde, James S

    2011-01-01

    Whole brain functional connectivity magnetic resonance imaging requires acquisition of a time course of gradient-recalled (GR) volumetric images. A method is developed to accelerate this acquisition using GR echo-planar imaging and radio frequency (RF) slice phase tagging. For N-fold acceleration, a tailored RF pulse excites N slices using a uniform-field transmit coil. This pulse is the Fourier transform of the profile for the N slices with a predetermined RF phase tag on each slice. A multichannel RF receive coil is used for detection. For n slices, there are n/N groups of slices. Signal-averaged reference images are created for each slice within each slice group for each member of the coil array and used to separate overlapping images that are simultaneously received. The time-overhead for collection of reference images is small relative to the acquisition time of a complete volumetric time course. A least-squares singular value decomposition method allows image separation on a pixel-by-pixel basis. Twofold slice acceleration is demonstrated using an eight-channel RF receive coil, with application to resting-state functional magnetic resonance imaging in the human brain. Data from six subjects at 3 T are reported. The method has been extended to half k-space acquisition, which not only provides additional acceleration, but also facilitates slice separation because of increased signal intensity of the central lines of k-space coupled with reduced susceptibility effects. PMID:22432957

  7. Strange Particle Production in pp Collisions at sqrt(s) = 0.9 and 7 TeV

    SciTech Connect

    Khachatryan, Vardan; et al.

    2011-05-01

    The spectra of strange hadrons are measured in proton-proton collisions, recorded by the CMS experiment at the CERN LHC, at centre-of-mass energies of 0.9 and 7 TeV. The K0_s, Lambda, and Xi^- particles and their antiparticles are reconstructed from their decay topologies and the production rates are measured as functions of rapidity and transverse momentum. The results are compared to other experiments and to predictions of the PYTHIA Monte Carlo program. The transverse momentum distributions are found to differ substantially from the PYTHIA results and the production rates exceed the predictions by up to a factor of three.

  8. Strangeness production in deep inelastic muon nucleon scattering at 280 GeV

    NASA Astrophysics Data System (ADS)

    Arneodo, M.; Arvidson, A.; Aubert, J. J.; Badelek, B.; Beaufays, J.; Bee, C. P.; Benchouk, C.; Berghoff, G.; Bird, I.; Blum, D.; Böhm, E.; de Bouard, X.; Brasse, F. W.; Braun, H.; Broll, C.; Brown, S.; Brück, H.; Calen, H.; Chima, J. S.; Ciborowski, J.; Clifft, R.; Coignet, G.; Combley, F.; Coughlan, J.; D'Agostini, G.; Dahlgren, S.; Dengler, F.; Derado, I.; Dreyer, T.; Drees, J.; Düren, M.; Eckhardt, V.; Edwards, A.; Edwards, M.; Ernst, T.; Eszes, G.; Favier, J.; Ferrero, M. I.; Figiel, J.; Flauger, W.; Foster, J.; Gabathuler, E.; Gajewski, J.; Gamet, R.; Gayler, J.; Geddes, N.; Grafström, P.; Grard, F.; Haas, J.; Hagberg, E.; Hasert, F. J.; Hayman, P.; Heusse, P.; Jaffré, M.; Jacholkowska, A.; Janata, F.; Jancso, G.; Johnson, A. S.; Kabuss, E. M.; Kellner, G.; Korbel, V.; Krüger, J.; Kullander, S.; Landgraf, U.; Lanske, D.; Loken, J.; Long, K.; Maire, M.; Malecki, P.; Manz, A.; Maselli, S.; Mohr, W.; Montanet, F.; Montgomery, H. E.; Nagy, E.; Nassalski, J.; Norton, P. R.; Oakham, F. G.; Osborne, A. M.; Pascaud, C.; Pawlik, B.; Payre, P.; Peroni, C.; Peschel, H.; Pessard, H.; Pettingale, J.; Pietrzyk, B.; Pönsgen, B.; Pötsch, M.; Renton, P.; Ribarics, P.; Rith, K.; Rondio, E.; Sandacz, A.; Scheer, M.; Schlagböhmer, A.; Schiemann, H.; Schmifz, N.; Schneegans, M.; Scholz, M.; Schröder, T.; Schouten, M.; Schultze, K.; Sloan, T.; Stier, H. E.; Studt, M.; Taylor, G. N.; Thénard, J. M.; Thompson, J. C.; de La Torre, A.; Toth, J.; Urban, L.; Wallucks, W.; Whalley, M.; Wheeler, S.; Williams, W. S. C.; Wimpenny, S. J.; Windmolders, R.

    1987-09-01

    The production of strange particles has been studied in a 280 GeV muon nucleon scattering experiment with acceptance and particle identification over a large kinematical range. The data show that at large values of x Bj the interactions take place mostly on a u valence quark in agreement with the basic quarkparton model predictions. This feature results in a strong forward-backward asymmetry in the distribution of strangeness along the rapidity axis. The data are compatible with a strange to non-strange quark suppression factor of ≈0.3 and with a strong suppression of strange diquarks. The distributions of K + K - pairs show that the two kaons are preferentially produced at neighbouring values of rapidity.

  9. Using the Moon As A Low-Noise Seismic Detector For Strange Quark Nuggets

    NASA Technical Reports Server (NTRS)

    Banerdt, W. Bruce; Chui, Talso; Griggs, Cornelius E.; Herrin, Eugene T.; Nakamura, Yosio; Paik, Ho Jung; Penanen, Konstantin; Rosenbaum, Doris; Teplitz, Vigdor L.; Young, Joseph

    2006-01-01

    Strange quark matter made of up, down and strange quarks has been postulated by Witten [1]. Strange quark matter would be nearly charge neutral and would have density of nuclear matter (10(exp 14) gm/cu cm). Witten also suggested that nuggets of strange quark matter, or strange quark nuggets (SQNs), could have formed shortly after the Big Bang, and that they would be viable candidates for cold dark matter. As suggested by de Rujula and Glashow [2], an SQN may pass through a celestial body releasing detectable seismic energy along a straight line. The Moon, being much quieter seismically than the Earth, would be a favorable place to search for such events. We review previous searches for SQNs to illustrate the parameter space explored by using the Moon as a low-noise detector of SQNs. We also discuss possible detection schemes using a single seismometer, and using an International Lunar Seismic Network.

  10. Speech neglect: A strange educational blind spot

    NASA Astrophysics Data System (ADS)

    Harris, Katherine Safford

    2005-09-01

    Speaking is universally acknowledged as an important human talent, yet as a topic of educated common knowledge, it is peculiarly neglected. Partly, this is a consequence of the relatively recent growth of research on speech perception, production, and development, but also a function of the way that information is sliced up by undergraduate colleges. Although the basic acoustic mechanism of vowel production was known to Helmholtz, the ability to view speech production as a physiological event is evolving even now with such techniques as fMRI. Intensive research on speech perception emerged only in the early 1930s as Fletcher and the engineers at Bell Telephone Laboratories developed the transmission of speech over telephone lines. The study of speech development was revolutionized by the papers of Eimas and his colleagues on speech perception in infants in the 1970s. Dissemination of knowledge in these fields is the responsibility of no single academic discipline. It forms a center for two departments, Linguistics, and Speech and Hearing, but in the former, there is a heavy emphasis on other aspects of language than speech and, in the latter, a focus on clinical practice. For psychologists, it is a rather minor component of a very diverse assembly of topics. I will focus on these three fields in proposing possible remedies.

  11. An almost symmetric Strang splitting scheme for nonlinear evolution equations☆

    PubMed Central

    Einkemmer, Lukas; Ostermann, Alexander

    2014-01-01

    In this paper we consider splitting methods for the time integration of parabolic and certain classes of hyperbolic partial differential equations, where one partial flow cannot be computed exactly. Instead, we use a numerical approximation based on the linearization of the vector field. This is of interest in applications as it allows us to apply splitting methods to a wider class of problems from the sciences. However, in the situation described, the classic Strang splitting scheme, while still being a method of second order, is not longer symmetric. This, in turn, implies that the construction of higher order methods by composition is limited to order three only. To remedy this situation, based on previous work in the context of ordinary differential equations, we construct a class of Strang splitting schemes that are symmetric up to a desired order. We show rigorously that, under suitable assumptions on the nonlinearity, these methods are of second order and can then be used to construct higher order methods by composition. In addition, we illustrate the theoretical results by conducting numerical experiments for the Brusselator system and the KdV equation. PMID:25844017

  12. Electroproduction of baryon-meson states and strangeness suppression

    NASA Astrophysics Data System (ADS)

    Santopinto, E.; García-Tecocoatzi, H.; Bijker, R.

    2016-08-01

    We describe the electroproduction ratios of baryon-meson states from nucleon, inferring from the sea quarks in the nucleon using an extension of the quark model that takes into account the sea. As a result we provide, with no adjustable parameters, the predictions of ratios of exclusive meson-baryon final states: ΛK+, Σ* K, ΣK, pπ0, and nπ+. These predictions are in agreement with the new JLab experimental data showing that sea quarks play an important role in the electroproduction. We also predicted further ratios of exclusive reactions that can be measured and tested in future experiments. In particular, we suggested new experiments on deuterium and tritium. Such measurements can provide crucial tests of different predictions concerning the structure of nucleon and its sea quarks helping to solve an outstanding problem. Finally, we compute the so called strangeness suppression factor, λs, that is the suppression of strange quark-antiquark pairs compared to nonstrange pairs, and we found that our finding with this simple extension of the quark model is in good agreement with the results of JLab and CERN experiments.

  13. Detectability of strange matter in heavy ion experiments

    SciTech Connect

    Schaffner, J.,; Diener, A.; Stocker, H.,; Greiner, C.,

    1997-06-01

    We discuss the properties of two distinct forms of hypothetical strange matter, small lumps of strange quark matter (strangelets) and of hyperon matter [metastable exotic multihypernuclear objects (MEMO{close_quote}s)], with special emphasis on their relevance for present and future heavy ion experiments. The masses of small strangelets up to A{sub B}=40 are calculated using the MIT bag model with shell mode filling for various bag parameters. The strangelets are checked for possible strong and weak hadronic decays, also taking into account multiple hadron decays. It is found that strangelets which are stable against strong decay are most likely highly negatively charged, contrary to previous findings. Strangelets can be stable against weak hadronic decay but their masses and charges are still rather high. This has serious impact on the present high sensitivity searches in heavy ion experiments at the AGS and CERN facilities. On the other hand, highly charged MEMO{close_quote}s are predicted on the basis of an extended relativistic mean-field model. Those objects could be detected in future experiments searching for short-lived, rare composites. It is demonstrated that future experiments can be sensitive to a much wider variety of strangelets. {copyright} {ital 1997} {ital The American Physical Society}

  14. Gamma-ray bursts from colliding strange stars

    NASA Technical Reports Server (NTRS)

    Haensel, P.; Paczynski, B.; Amsterdamski, P.

    1991-01-01

    The rate of collisions between the neutron stars is about 0.0001/yr in the galaxy and about 0.00001/yr within the Hubble distance. The collisions are the final phases of binary orbit decay driven by gravitational radiation and may produce gamma-ray bursts detectable at extragalactic distances. If strange stars exist then their collisions must release about 10 to the 50th ergs in gamma rays over 0.2 s. Such events should be detectable out to 1 Gpc with the current instruments. The distance to the majority of gamma-ray bursts is not known at this time. The Burst and Transient Source Experiment (BATSE) on Gamma Ray Observatory should determine the distance scale by determining the angular distribution of very weak bursts. If the majority of gamma-ray bursts turn out to be extragalactic, and if their distances are about 1 Gpc, then the collisions between strange stars may be the least speculative events that might account for so energetic bursts.

  15. Zero sound in strange metals with hyperscaling violation from holography

    NASA Astrophysics Data System (ADS)

    Dey, Parijat; Roy, Shibaji

    2013-08-01

    Hyperscaling violating “strange metal” phase of heavy fermion compounds can be described holographically by probe D-branes in the background of a Lifshitz space-time (dynamical exponent z and spatial dimensions d) with hyperscaling violation (corresponding exponent θ). Without the hyperscaling violation, strange metals are known to exhibit zero sound mode for z<2 analogous to the Fermi liquids. In this paper, we study its fate in the presence of hyperscaling violation and find that in this case, the zero sound mode exists for z<2(1+|θ|/d), where the positivity of the specific heat and the null energy condition of the background dictate that θ<0 and z≥1. However, for z≥2(1+|θ|/d), there is no well-defined quasiparticle for the zero sound. The systems behave like Fermi liquid for 2|θ|=dz and like Bose liquid for 2|θ|=qdz (where q is the number of spatial dimensions along which D-branes are extended in the background space), but in general they behave as a new kind of quantum liquid. We also compute the ac conductivity of the systems and briefly comment on the results.

  16. Excited baryon structure using exclusive reactions with CLAS12

    NASA Astrophysics Data System (ADS)

    Carman, Daniel S.

    2016-05-01

    Studying excited nucleon structure through exclusive electroproduction reactions is an important avenue for exploring the nature of the non-perturbative strong interaction. Electrocouplings for N* states in the mass range below 1.8 GeV have been determined from analyses of CLAS πN, ηN, and ππN data. This work made it clear that consistency of independent analyses of exclusive channels with different couplings and non-resonant backgrounds but the same N* electro-excitation amplitudes, is essential to have confidence in the extracted results. In terms of hadronic coupling, many high-lying N* states preferentially decay through the ππN channel instead of πN. Data from the KY channels will therefore be critical to provide an independent analysis with which to compare the extracted electrocouplings for the high-lying N* states against those determined from the πN and ππN channels. A program to study excited N* decays to non-strange and strange exclusive final states using CLAS12 will measure differential cross sections to be used as input to extract the γvNN* transition form factors for the most prominent N* states in the range of invariant energy W up 3 GeV in the virtually unexplored domain of momentum transfers Q2 up to 12 GeV2.

  17. Reaction mechanism in the {sup 16}O+{sup 27}Al system: Measurements and analysis of excitation functions and angular distributions

    SciTech Connect

    Sharma, Manoj Kumar; Unnati,; Singh, Devendra P.; Singh, Pushpendra P.; Singh, B. P.; Prasad, R.; Bhardwaj, H. D.

    2007-06-15

    To study the dynamics of heavy ion fusion reactions in the lower mass region, experiments were carried out to measure the cross sections of radioactive residues produced in the interaction of the {sup 16}O ion with {sup 27}Al target nucleus at 19 different energies in very close intervals covering the energy range from {approx_equal}58 to 94 MeV, using the well-known recoil catcher off-line {gamma}-ray spectroscopy technique. The simulation of experimental data was performed using statistical-model-based computer codes, viz., CASCADE, PACE2, and ALICE-91. The analysis of measured excitation functions indicates that these residues are likely to be produced by complete fusion, incomplete fusion, and direct reaction processes. Furthermore, to confirm the contribution of different reaction channels, a complementary experiment was performed that measured the angular distributions of the residues produced in the {sup 16}O+{sup 27}Al system at 85 MeV beam energy. The analysis of the results of both experiments indicates that at these energies, the direct reactions compete with complete fusion and incomplete fusion reaction processes.

  18. Time-dependent density-matrix functional theory for trion excitations: Application to monolayer MoS2 and other transition-metal dichalcogenides

    NASA Astrophysics Data System (ADS)

    Ramirez-Torres, Alfredo; Turkowski, Volodymyr; Rahman, Talat S.

    2014-08-01

    To examine optically excited bound states, excitons and trions, in monolayer MoS2,MoSe2, and WSe2, we have formulated and applied a generalized time-dependent density-matrix functional theory approach. Three different types of exchange-correlation (XC) kernels were used and their validity was evaluated through comparison with available experimental data. For excitons, we find that the local kernels, from the local density approximation and its gradient-corrected form, lead to much smaller binding energy than that extracted from experimental data, while those based on long-range (LR) interactions fare much better. The same is the case for the trion binding energy once screening effects are taken into account. Our results suggest that for both excitons and trions, the LR form of the XC kernel is necessary to describe bound states. These results confirm information from experimental data on single-layer dichalcogenides that their exciton and trion binding energies are of the order of hundreds (excitons) and tens (trions) of milli-electron volts, a result that may suggest technological application of these materials at room temperature. The proposed methodology can be straightforwardly extended to bound states with a larger number of electrons and holes than considered here.

  19. Density functional theory calculations on rhodamine B and pinacyanol chloride. Optimized ground state, dipole moment, vertical ionization potential, adiabatic electron affinity and lowest excited triplet state.

    PubMed

    Delgado, Juan C; Selsby, Ronald G

    2013-01-01

    The ground state configuration of the gas phase cationic dyes pinacyanol chloride and rhodamine B are optimized with HF/6-311 + G(2d,2p) method and basis set. B3PW91/6-311 + G(2df,2p) functional and basis set is used to calculate the Mulliken atom charge distribution, total molecular energy, the dipole moment, the vertical ionization potential, the adiabatic electron affinity and the lowest excited triplet state, the last three as an energy difference between separately calculated open shell and ground states. The triplet and extra electron states are optimized to find the relaxation energy. In the ground state optimization of both dyes the chloride anion migrates to a position near the center of the chromophore. For rhodamine B the benzoidal group turns perpendicular to the chromophore plane. For both dyes, the LUMO is mostly of π character associated with the aromatic part of the molecule containing the chromophore. The highest occupied MOs consist of three almost degenerate eigenvectors involving the chloride anion coordinated with σ electrons in the molecular framework. The fourth highest MO is of π character. For both molecules in the gas phase ionization process the chloride anion loses the significant fraction of electric charge. In electron capture, the excess charge goes mainly on the dye cation. PMID:22891949

  20. Linker mutations dissociate the function of synaptotagmin I during evoked and spontaneous release and reveal membrane penetration as a step during excitation-secretion coupling

    PubMed Central

    Liu, Huisheng; Bai, Hua; Xue, Renhao; Takahashi, Hirohide; Edwardson, J. Michael; Chapman, Edwin R.

    2014-01-01

    The Ca2+ sensor for rapid synaptic vesicle exocytosis, synaptotagmin I (syt), is largely composed of two Ca2+-sensing C2-domains, C2A and C2B. We have investigated the apparent synergy between the tandem C2 domains by altering the length and rigidity of the linker that connects them. The behavior of the linker mutants revealed a correlation between the ability of the C2-domains to penetrate membranes in response to Ca2+ and to drive evoked neurotransmitter release in cultured mouse neurons, uncovering a step in excitation-secretion coupling. Atomic force microscopy experiments indicate that the synergy between these C2-domains involves intra-molecular interactions between them. Thus, syt function is profoundly affected by changes in the physical nature of the linker that connects its tandem C2-domains. Moreover, the linker mutations uncoupled syt-mediated regulation of evoked and spontaneous release, revealing that syt also acts as a fusion clamp prior to the Ca2+ trigger. PMID:24657966

  1. Excitation function for the production of {sup 262}Bh (Z=107) in the odd-Z-projectile reaction {sup 208}Pb({sup 55}Mn, n)

    SciTech Connect

    Folden, C.M. III; Nelson, S.L.; Duellmann, Ch.E.; Schwantes, J.M.; Zielinski, P.M.; Nitsche, H.; Hoffman, D.C.; Sudowe, R.; Gregorich, K.E.

    2006-01-15

    The excitation function for production of {sup 262}Bh in the odd-Z-projectile reaction {sup 208}Pb({sup 55}Mn, n) has been measured at three projectile energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, 33 decay chains originating from {sup 262}Bh and 2 decay chains originating from {sup 261}Bh were observed. The measured decay properties are in good agreement with previous reports. The maximum cross section of 540{sub -150}{sup +180} pb is observed at a lab-frame center-of-target energy of 264.0 MeV and is more than five times larger than that expected based on previously reported results for production of {sup 262}Bh in the analogous even-Z-projectile reaction {sup 209}Bi({sup 54}Cr, n). Our results indicate that the optimum beam energy in one-neutron-out heavy-ion fusion reactions can be estimated simply using the optimum energy rule proposed by SwiaPtecki, Siwek-Wilczynska, and Wilczynski.

  2. Excitation function for the production of 262Bh (Z = 107) in theodd-Z projectile reaction 208Pb(55Mn, n)

    SciTech Connect

    Folden III, C.M.; Nelson, S.L.; Dullmann, Ch.E.; Schwantes, J.M.; Sudowe, R.; Zielinski, P.M.; Gregorich, K.E.; Nitsche, H.; Hoffman, D.C.

    2005-05-16

    The excitation function for production of 262Bh in the odd-Z-projectile reaction 208Pb(55Mn,n) has been measured at three projectile energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, 33 decay chains originating from 262Bh and 2 decay chains originating from 261Bh were observed. The measured decay properties are in good agreement with previous reports. The maximum cross section of 540 +180 - 150 pb is observed at a lab-frame center-of-target energy of 264.0 MeV and is more than fives times larger than that expected based on previously reported results for production of 262Bh in the analogous even-Z-projectile reaction 209Bi(54Cr,n). Our results indicate that the optimum beam energy in one-neutron-out heavy-ion fusion reactions can be estimated simply using the ''Optimum Energy Rule'' proposed by Swiatecki, Siwek-Wilczynska, and Wilczynski.

  3. Acupuncture Relieves the Excessive Excitation of Hypothalamic-Pituitary-Adrenal Cortex Axis Function and Correlates with the Regulatory Mechanism of GR, CRH, and ACTHR

    PubMed Central

    Wang, Shao-Jun; Zhang, Jiao-Jiao; Qie, Li-Li

    2014-01-01

    It had been indicated in the previous studies that acupuncture relieved the excessive excitation of hypothalamic-pituitary-adrenal cortex axis (HPAA) function induced by stress stimulation. But the changes in glucocorticoid receptor (GR) induced by acupuncture have not been detected clearly. The objective of the study was to observe the impacts of acupuncture on the protein expressions of corticotrophin releasing hormone (CRH), adrenocorticotropic hormone receptor (ACTHR), and GR under the physiological and stress states. The results showed that under the stress state, acupuncture upregulated the protein expression of GR in the hippocampus, hypothalamic paraventricular nucleus (PVN), and pituitary gland, downregulated the protein expression of GR in the adrenal cortex, and obviously reduced the protein expressions of CRH and ACTHR. Under the physiological state, acupuncture promoted GR protein expression in the hippocampus and CRH protein expression in the hippocampus and PVN. The results explained that acupuncture regulated the stress reaction via promoting the combination of glucocorticoids (GC) with GR, and GR protein expression. The increase of GR protein expression induced feedback inhibition on the overexpression of CRH and ACTHR, likely decreased GC level, and caused the reduction of GR protein expression in the adrenal cortex. PMID:24761151

  4. On the relation between time-dependent and variational density functional theory approaches for the determination of excitation energies and transition moments.

    PubMed

    Ziegler, Tom; Seth, Michael; Krykunov, Mykhaylo; Autschbach, Jochen; Wang, Fan

    2009-04-21

    It is shown that it is possible to derive the basic eigenvalue equation of adiabatic time-dependent density functional theory within the Tamm-Dancoff approximation (TD-DFT/TD) from a variational principle. The variational principle is applied to the regular Kohn-Sham formulation of DFT energy expression for a single Slater determinant and leads to the same energy spectrum as TD-DFT/TD. It is further shown that this variational approach affords the same electric and magnetic transition moments as TD-DFT/TD. The variational scheme can also be applied without the Tamm-Dancoff approximation. Practical implementations of TD-DFT are limited to second order response theory which introduces errors in transition energies for charge transfer and Rydberg excitations. It is indicated that higher order terms can be incorporated into the variational approach. It is also discussed how the current variational method is related to traditional DFT schemes based on variational principles such as DeltaSCF-DFT, and how they can be combined. PMID:19388731

  5. Raptor ablation in skeletal muscle decreases Cav1.1 expression and affects the function of the excitation-contraction coupling supramolecular complex.

    PubMed

    Lopez, Rubén J; Mosca, Barbara; Treves, Susan; Maj, Marcin; Bergamelli, Leda; Calderon, Juan C; Bentzinger, C Florian; Romanino, Klaas; Hall, Michael N; Rüegg, Markus A; Delbono, Osvaldo; Caputo, Carlo; Zorzato, Francesco

    2015-02-15

    The protein mammalian target of rapamycin (mTOR) is a serine/threonine kinase regulating a number of biochemical pathways controlling cell growth. mTOR exists in two complexes termed mTORC1 and mTORC2. Regulatory associated protein of mTOR (raptor) is associated with mTORC1 and is essential for its function. Ablation of raptor in skeletal muscle results in several phenotypic changes including decreased life expectancy, increased glycogen deposits and alterations of the twitch kinetics of slow fibres. In the present paper, we show that in muscle-specific raptor knockout (RamKO), the bulk of glycogen phosphorylase (GP) is mainly associated in its cAMP-non-stimulated form with sarcoplasmic reticulum (SR) membranes. In addition, 3[H]-ryanodine and 3[H]-PN200-110 equilibrium binding show a ryanodine to dihydropyridine receptors (DHPRs) ratio of 0.79 and 1.35 for wild-type (WT) and raptor KO skeletal muscle membranes respectively. Peak amplitude and time to peak of the global calcium transients evoked by supramaximal field stimulation were not different between WT and raptor KO. However, the increase in the voltage sensor-uncoupled RyRs leads to an increase of both frequency and mass of elementary calcium release events (ECRE) induced by hyper-osmotic shock in flexor digitorum brevis (FDB) fibres from raptor KO. The present study shows that the protein composition and function of the molecular machinery involved in skeletal muscle excitation-contraction (E-C) coupling is affected by mTORC1 signalling. PMID:25431931

  6. Proper Restoration of Excitation-Contraction Coupling in the Dihydropyridine Receptor β1-null Zebrafish Relaxed Is an Exclusive Function of the β1a Subunit*

    PubMed Central

    Schredelseker, Johann; Dayal, Anamika; Schwerte, Thorsten; Franzini-Armstrong, Clara; Grabner, Manfred

    2009-01-01

    The paralyzed zebrafish strain relaxed carries a null mutation for the skeletal muscle dihydropyridine receptor (DHPR) β1a subunit. Lack of β1a results in (i) reduced membrane expression of the pore forming DHPR α1S subunit, (ii) elimination of α1S charge movement, and (iii) impediment of arrangement of the DHPRs in groups of four (tetrads) opposing the ryanodine receptor (RyR1), a structural prerequisite for skeletal muscle-type excitation-contraction (EC) coupling. In this study we used relaxed larvae and isolated myotubes as expression systems to discriminate specific functions of β1a from rather general functions of β isoforms. Zebrafish and mammalian β1a subunits quantitatively restored α1S triad targeting and charge movement as well as intracellular Ca2+ release, allowed arrangement of DHPRs in tetrads, and most strikingly recovered a fully motile phenotype in relaxed larvae. Interestingly, the cardiac/neuronal β2a as the phylogenetically closest, and the ancestral housefly βM as the most distant isoform to β1a also completely recovered α1S triad expression and charge movement. However, both revealed drastically impaired intracellular Ca2+ transients and very limited tetrad formation compared with β1a. Consequently, larval motility was either only partially restored (β2a-injected larvae) or not restored at all (βM). Thus, our results indicate that triad expression and facilitation of 1,4-dihydropyridine receptor (DHPR) charge movement are common features of all tested β subunits, whereas the efficient arrangement of DHPRs in tetrads and thus intact DHPR-RyR1 coupling is only promoted by the β1a isoform. Consequently, we postulate a model that presents β1a as an allosteric modifier of α1S conformation enabling skeletal muscle-type EC coupling. PMID:19008220

  7. A new form of strange matter and new hope for finding it

    SciTech Connect

    Flam, F.

    1993-10-08

    Deep in the dense cores of collapsed stars even atoms don't survive. The force of gravity crushes them into particle mushes weighing megatons per teaspoon. But even these alien forms of matter don't hold a candle to another possible end product of a collapsing star: something physicists justifiably call strange matter. This strangeness comes from an exotic particle not associated with ordinary matter: the strange quark. It belongs to a six-member quark family, along with up, down, charm, top, and bottom, each of which carries a different combination of charge and mass. The only ones that make up matter as we know it are up and down quarks, but in theory, matter could form out of strange quarks as well. In nature, it would turn up most probably in interiors of collapsed stars. Scientists originally imagined strange matter as a sort of disorganized mixed bag of strange quarks, but this summer a group proposed that the quarks could form a sort of mutant atomic nucleus that could conceivably grow to the size of a star. For the moment this is speculation, but it may not be theoretical musing for long. Physicists are preparing to try making strange matter here on Earth, in experiments at Brookhaven National Laboratory in New York and Switzerland's CERN, next summer.

  8. Volcanic termor: Nonlinear excitation by fluid flow

    NASA Astrophysics Data System (ADS)

    Julian, Bruce R.

    1994-06-01

    A nonlinear process analogous to the excitation mechanism of musical wind instruments and human vocal cords can explain many characteristics of volcanic tremor, including (1) periodic and 'chaotic' oscillations, with peaked and irregular spectra respectively, (2) rapid pulsations in eruptions occurring at the same frequency as tremor, (3) systematic changes in tremor amplitude as channel geometry evolves during an eruption, (4) the period doubling reported for Hawaiian deep tremor, and (5) the fact that the onset of termor can be either gradual or abrupt. Volcanic 'long-period' earthquakes can be explained as oscillations excited by transient disturbances produced by nearby earthquakes, fluid heterogeneity, or changes in channel geometry, when the magma flow rate is too low to excite continuous tremor. A simple lumped-parameter tremor model involving the flow of an incompressible viscous fluid through a channel with movable elastic walls leads to a third-order system of nonlinear ordinary differential equations. For different driving fluid pressures, numerical solutions exhibit steady flow, simple limit-cycle oscillations, a cascade of period-doubling subharmonic bifurcations, and chaotic oscillations controlled by a strange attractor of Rossler type. In this model, tremor occurs most easily at local constrictions, and fluid discharge is lower than would occur in unstable steady flow.

  9. Detection of symmetry-protected topological order in AKLT states by exact evaluation of the strange correlator

    NASA Astrophysics Data System (ADS)

    Wierschem, K.; Beach, K. S. D.

    2016-06-01

    The strange correlator [Phys. Rev. Lett. 112, 247202 (2014), 10.1103/PhysRevLett.112.247202] has been proposed as a measure of symmetry protected topological order in one- and two-dimensional systems. It takes the form of a spin-spin correlation function, computed as a mixed overlap between the state of interest and a trivial local product state. We demonstrate that it can be computed exactly (asymptotically, in the Monte Carlo sense) for various Affleck-Kennedy-Lieb-Tasaki states by direct evaluation of the wave function within the valence bond loop gas framework. We present results for lattices with chain, square, honeycomb, cube, diamond, and hyperhoneycomb geometries. In each case, the spin quantum number S is varied such that 2 S (the number of valence bonds emerging from each site) achieves various integer multiples of the lattice coordination number. We introduce the concept of strange correlator loop winding number and point to its utility in testing for the presence of symmetry protected topological order.

  10. Centrality dependence of elliptic flow of multi-strange hadrons in Au+Au collisions at √sNN = 200 GeV

    NASA Astrophysics Data System (ADS)

    Shi, Shusu

    2016-01-01

    We present recent results of the mid-rapidity elliptic flow (ν2) for multi-strange hadrons and the ϕ meson as a function of centrality in Au + Au collisions at the center of mass energy √sNN = 200 GeV. The transverse momentum dependence of ϕ and Ω ν2 is similar to that of pion and proton, indicating that the heavier strange (s) quark flows as strongly as the lighter up (u) and down (d) quarks. These observations constitute a clear piece of evidence for the development of partonic collectivity in heavy-ion collisions at the top RHIC energy. In addition, the mass ordering of ν2 breaks between the ϕ and proton at low transverse momenta in the 0-30% centrality bin, possibly due to the effect of late hadronic interactions on the proton ν2.

  11. Comment on "Reevaluation of the parton distribution of strange quarks in the nucleon"

    NASA Astrophysics Data System (ADS)

    Stolarski, M.

    2015-11-01

    The HERMES collaboration in Phys. Rev. D 89, 097101 (2014) extracted information about the strange quark density in the nucleon. One of the main results is an observation that the shape of the extracted density is very different from the shapes of the strange quark density from global QCD fits and also from that of the light antiquarks. In this paper systematic studies on the HERMES published multiplicity of pion and kaon data are presented. It is shown that the conclusions concerning the strange quark distribution in the nucleon reached in Phys. Rev. D 89, 097101 (2014) are at the moment premature.

  12. Bare Quark Matter Surfaces of Strange Stars and e+e- Emission

    NASA Astrophysics Data System (ADS)

    Usov, V. V.

    1998-01-01

    We show that the Coulomb barrier at the quark surface of a hot strange star may be a powerful source of e+e- pairs which are created in an extremely strong electric field of the barrier and flow away from the star. The luminosity in the outflowing pair plasma depends on the surface temperature TS and may be very high, up to ~3×1051 ergs s-1 at TS~1011 K. The effect of pair creation by the Coulomb barrier may be a good observational signature of strange stars which can give an answer to the question of whether a compact object is a neutron or strange star.

  13. Theoretical studies of electronically excited states

    SciTech Connect

    Besley, Nicholas A.

    2014-10-06

    Time-dependent density functional theory is the most widely used quantum chemical method for studying molecules in electronically excited states. However, excited states can also be computed within Kohn-Sham density functional theory by exploiting methods that converge the self-consistent field equations to give excited state solutions. The usefulness of single reference self-consistent field based approaches for studying excited states is demonstrated by considering the calculation of several types of spectroscopy including the infrared spectroscopy of molecules in an electronically excited state, the rovibrational spectrum of the NO-Ar complex, core electron binding energies and the emission spectroscopy of BODIPY in water.

  14. Redox Control of Cardiac Excitability

    PubMed Central

    Aggarwal, Nitin T.

    2013-01-01

    Abstract Reactive oxygen species (ROS) have been associated with various human diseases, and considerable attention has been paid to investigate their physiological effects. Various ROS are synthesized in the mitochondria and accumulate in the cytoplasm if the cellular antioxidant defense mechanism fails. The critical balance of this ROS synthesis and antioxidant defense systems is termed the redox system of the cell. Various cardiovascular diseases have also been affected by redox to different degrees. ROS have been indicated as both detrimental and protective, via different cellular pathways, for cardiac myocyte functions, electrophysiology, and pharmacology. Mostly, the ROS functions depend on the type and amount of ROS synthesized. While the literature clearly indicates ROS effects on cardiac contractility, their effects on cardiac excitability are relatively under appreciated. Cardiac excitability depends on the functions of various cardiac sarcolemal or mitochondrial ion channels carrying various depolarizing or repolarizing currents that also maintain cellular ionic homeostasis. ROS alter the functions of these ion channels to various degrees to determine excitability by affecting the cellular resting potential and the morphology of the cardiac action potential. Thus, redox balance regulates cardiac excitability, and under pathological regulation, may alter action potential propagation to cause arrhythmia. Understanding how redox affects cellular excitability may lead to potential prophylaxis or treatment for various arrhythmias. This review will focus on the studies of redox and cardiac excitation. Antioxid. Redox Signal. 18, 432–468. PMID:22897788

  15. Strange quarks in the nucleon sea: Results from HAPPEX II

    SciTech Connect

    K.A. Aniol; HAPPEX Collaboration

    2007-03-01

    The HAPPEX Collaboration measured parity-violating electron scattering from 4He(e, e) and H(e, e) in 2004 and 2005 for Q2 ≤ 0.11 GeV2. Results for the strange-quark contributions to the electromagnetic form factors of the nucleon from the 2004 data will be reviewed. Preliminary results from the 2005 data, which have significantly greater statistical precision, are GsE = 0.004 0.014stat 0.013syst for Q2 = 0.0772 GeV2 from the helium data and GsE + 0.088 GsM = 0.004 0.011stat 0.005syst 0.004FF for Q2 = 0.1089 GeV2 from the hydrogen data.

  16. Search for Stable Strange Quark Matter in Lunar Soil

    SciTech Connect

    Han, K.; Chikanian, A.; Emmet, W.; Finch, L. E.; Majka, R. D.; Sandweiss, J.; Ashenfelter, J.; Heinz, A.; Madsen, J.; Monreal, B.

    2009-08-28

    We report results from a search for strangelets (small chunks of strange quark matter) in lunar soil using the Yale WNSL accelerator as a mass spectrometer. We have searched over a range in mass from A=42 to A=70 amu for nuclear charges 5, 6, 8, 9, and 11. No strangelets were found in the experiment. For strangelets with nuclear charge 8, a concentration in lunar soil higher than 10{sup -16} is excluded at the 95% confidence level. The implied limit on the strangelet flux in cosmic rays is the most sensitive to date for the covered range and is relevant to both recent theoretical flux predictions and a strangelet candidate event found by the AMS-01 experiment.

  17. Probing Proton Strangeness with Time-Like Virtual Compton Scattering

    SciTech Connect

    Stephen R. Cotanch; Robert A. Williams

    2002-05-01

    We document that p(gamma,e+e-)p measurements will yield new, important information about the off-shell time-like nucleon form factors, especially in the phi meson region (q{sup 2} = M{sup 2}{sub {phi}}) governing the phi N couplings g{sup V,T}{sub {phi}NN}. Calculations for p(gamma,e+e-)p, utilizing vector meson dominance, predict measurable phi enhancements at high |t| compared to the expected phi background production from pi, eta and Pomeron exchange. The phi form factor contribution generates a novel experimental signature for OZI violation and the proton strangeness content. The phi N couplings are determined independently from a combined analysis of the neutron electric form factor and recent high |t| phi photoproduction. The pi, eta and Pomeron transition form factors are also predicted and the observed pi and eta transition moments are reproduced.

  18. Functional Network Overlap as Revealed by fMRI Using sICA and Its Potential Relationships with Functional Heterogeneity, Balanced Excitation and Inhibition, and Sparseness of Neuron Activity

    PubMed Central

    Xu, Jiansong; Calhoun, Vince D.; Worhunsky, Patrick D.; Xiang, Hui; Li, Jian; Wall, John T.; Pearlson, Godfrey D.; Potenza, Marc N.

    2015-01-01

    Functional magnetic resonance imaging (fMRI) studies traditionally use general linear model-based analysis (GLM-BA) and regularly report task-related activation, deactivation, or no change in activation in separate brain regions. However, several recent fMRI studies using spatial independent component analysis (sICA) find extensive overlap of functional networks (FNs), each exhibiting different task-related modulation (e.g., activation vs. deactivation), different from the dominant findings of GLM-BA. This study used sICA to assess overlap of FNs extracted from four datasets, each related to a different cognitive task. FNs extracted from each dataset overlapped with each other extensively across most or all brain regions and showed task-related concurrent increases, decreases, or no changes in activity. These findings indicate that neural substrates showing task-related concurrent but different modulations in activity intermix with each other and distribute across most of the brain. Furthermore, spatial correlation analyses found that most FNs were highly consistent in spatial patterns across different datasets. This finding indicates that these FNs probably reflect large-scale patterns of task-related brain activity. We hypothesize that FN overlaps as revealed by sICA might relate to functional heterogeneity, balanced excitation and inhibition, and population sparseness of neuron activity, three fundamental properties of the brain. These possibilities deserve further investigation. PMID:25714362

  19. Equilibrium and stability of charged strange quark stars

    NASA Astrophysics Data System (ADS)

    Arbañil, José D. V.; Malheiro, M.

    2015-10-01

    The hydrostatic equilibrium and the stability against radial perturbation of charged strange quark stars composed of a charged perfect fluid are studied. For this purpose, it is considered that the perfect fluid follows the MIT bag model equation of state and the radial charge distribution follows a power-law. The hydrostatic equilibrium and the stability of charged strange stars are investigated through the numerical solutions of the Tolman-Oppenheimer-Volkoff equation and the Chandrasekhar's pulsation equation, being these equations modified from their original form to include the electrical charge. In order to appreciably affect the stellar structure, it is found that the total charge should be of order 1020 [C ] , implying an electric field of around 1022 [V /m ] . We found the electric charge that produces considerable effect on the structure and stability of the object is close to the star's surface. We obtain that for a range of central energy density the stability of the star decreases with the increment of the total charge and for a range of total mass the electric charge helps to grow the stability of the stars under study. We show that the central energy density used to reach the maximum mass value is the same used to determine the zero eigenfrequency of the fundamental mode when the total charge is fixed, thus indicating that the maximum mass point marks the onset of instability. In other words, when fixing the total charge, the conditions d/M d ρc >0 and d/M d ρc <0 are necessary and sufficient to determine the stable and unstable equilibrium configurations regions against radial oscillations. We also consider another charge distribution, charge density proportional to the energy density, and show that our results do not depend on this choice and the conditions used to determine regions made of the stable and unstable charged equilibrium configurations are maintained.

  20. Electronic structure and optical properties of CdS{sub x}Se{sub 1−x} solid solution nanostructures from X-ray absorption near edge structure, X-ray excited optical luminescence, and density functional theory investigations

    SciTech Connect

    Murphy, M. W.; Yiu, Y. M. Sham, T. K.; Ward, M. J.; Liu, L.; Hu, Y.; Zapien, J. A.; Liu, Yingkai

    2014-11-21

    The electronic structure and optical properties of a series of iso-electronic and iso-structural CdS{sub x}Se{sub 1−x} solid solution nanostructures have been investigated using X-ray absorption near edge structure, extended X-ray absorption fine structure, and X-ray excited optical luminescence at various absorption edges of Cd, S, and Se. It is found that the system exhibits compositions, with variable local structure in-between that of CdS and CdSe accompanied by tunable optical band gap between that of CdS and CdSe. Theoretical calculation using density functional theory has been carried out to elucidate the observations. It is also found that luminescence induced by X-ray excitation shows new optical channels not observed previously with laser excitation. The implications of these observations are discussed.

  1. Excitation functions of inelastic and transfer channels in {sup 12}C+{sup 12}C around E{sub c.m.}=32.5 MeV

    SciTech Connect

    Szilner, S.; Basrak, Z.

    1997-03-01

    A prominent and wide resonance centered at E{sub c.m.}=32.5 MeV has recently been found in the (0{sub 2}{sup +},0{sub 2}{sup +}) inelastic channel of the {sup 12}C+{sup 12}C reaction. It has been suggested that it corresponds to a 6{alpha}-particle-chain state in {sup 24}Mg. In the present work we study {sup 12}C+{sup 12}C excitation functions between center-of-mass energies of 30 and 35 MeV in steps of 250 keV for weakly populated outgoing channels. We present the inelastic channels to the states above the {alpha}-particle decay threshold, (0{sub 1}{sup +},0{sub 2}{sup +}), (0{sub 1}{sup +},3{sub 1}{sup {minus}}), and (0{sub 1}{sup +},4{sub 1}{sup +}), and the one- and two-nucleon transfer channels. In the inelastic and the transfer channels we observe correlated intermediate-width structures at E{sub c.m.}=31, 32.5, and 33.5 MeV, whose widths are appreciably smaller than the width measured in the (0{sub 2}{sup +},0{sub 2}{sup +}) channel. Our E{sub c.m.}=32.5 MeV angular distribution of the (0{sub 1}{sup +},0{sub 2}{sup +}) channel exhibits oscillatory behavior and, unlike that of the (0{sub 2}{sup +},0{sub 2}{sup +}) channel, does not display enhancement around {theta}{sub c.m.}=90{degree}. Data were collected via the kinematic coincidence technique. For data reduction we use a novel approach allowing for the extraction of results on nonbinary channels. {copyright} {ital 1997} {ital The American Physical Society}

  2. The investigation of strangeness photoproduction in the threshold region at ELPH-Tohoku

    NASA Astrophysics Data System (ADS)

    Kaneta, M.; Beckford, B.; Bydžovský, P.; Fujibayashi, T.; Fujii, T.; Fujii, Y.; Futatsukawa, K.; Gogami, T.; Han, Y. C.; Hashimoto, O.; Hirose, K.; Hosomi, K.; Honda, R.; Iguchi, A.; Ishikawa, T.; Kanda, H.; Kaneko, Y.; Kasai, Y.; Kawasaki, T.; Kimura, C.; Kiyokawa, S.; Koike, T.; Maeda, K.; Maruyama, N.; Matsubara, M.; Miwa, K.; Miyagi, Y.; Nagao, S.; Nakamura, S. N.; Okuyama, A.; Sotona, M.; Tamae, T.; Tamura, H.; Tsukada, K.; Terada, N.; Wang, T. S.; Yamamoto, F.; Yamamoto, T. O.; Yamazaki, H.

    2013-09-01

    The strangeness photoproduction processes near the threshold have been intensively studied by measuring K+ in reactions such as γ+p→K++Λ(Σ0). There has been no reliable data on the neutron and as a consequence theoretical investigation suffered seriously from the lack of the data. We have an effort to measure the γ+d→K0(Λ)+X reaction in the π+π- (pπ-) decay channel of KS0 (Λ) using a liquid D2 target and internally-tagged photon beams (Eγ=0.80-1.08 GeV) at Research Center for Electron Photon Science (ELPH), Tohoku University. We have renewed the spectrometer (NKS2) and took data with a liquid D2 target in 2005-2007. More recently, we took data in 2010 after a detector upgrade in the vertex region to substantially increase the acceptance. The results of Λ single measurements on a deuterium target were obtained for differential cross-section as a function of momentum, as a function of angle, and integrated cross-section as a function of beam energy. The results are compared with recent theoretical studies: Isobar models (Kaon-MAID and Saclay-Lyon A) and a Regge-plus-Resonance model.

  3. Investigation of Strangeness Photoproduction near the Threshold at ELPH, Tohoku University

    NASA Astrophysics Data System (ADS)

    Kaneta, Masashi; Beckford, Brian; Bydžovský, Petr; Fujibayashi, Takeshi; Fujii, Takao; Fujii, Yu; Futatsukawa, Kenta; Gogami, Toshiyuki; Han, Yuncheng; Hashimoto, Osamu; Hirose, Kentaro; Hosomi, Kenji; Honda, Ryotarou; Iguchi, Aran; Ishikawa, Takatsugu; Kanda, Hiroki; Kaneko, Yusuke; Kasai, Yuma; Kawasaki, Taito; Kimura, Chigusa; Kiyokawa, Shogo; Koike, Takeshi; Maeda, Kazushige; Maruyama, Nayuta; Matsubara, Masao; Miwa, Koji; Miyagi, Yohei; Nagao, Sho; Nakamura, Satoshi N.; Nishizawa, Takashi; Okuyama, Akira; Sotona, Miloslav; Tamae, Tadaaki; Tamura, Hirokazu; Tsukada, Kyo; Terada, Nobu; Wang, Tieshan; Yamamoto, Fumiya; Yamamoto, Takeshi O.; Yamazaki, Hirohito

    The strangeness photoproduction processes in the threshold region have been intensively studied by measuring K+ in reactions such as γ + P → K+ + Λ(Σ0). There has been no reliable data on the neutron and as a consequence theoretical investigation suffered seriously from the lack of the data. We have made a significant effort to measure the γ + d → K0(Λ) + X reaction in the π+π- (pπ-) decay channel of KS0 (Λ) using a liquid D2 target and internally-tagged photon beams (Eγ = 0.80-1.08 GeV) at Research Center for Electron Photon Science (ELPH), Tohoku University. We have renewed the spectrometer (NKS2) and took data with a liquid D2 target in 2005-2007. More recently, we took data in 2010 after a detector upgrade in the vertex region to substantially increase the acceptance. The results of Λ single measurements on a deuterium target were obtained for differential cross-section as a function of momentum, as a function of angle, and integrated cross-section as a function of beam energy. The results are compared with recent theoretical studies: Isobar models (Kaon-MAID and Saclay-Lyon A) and a Regge-plus-Resonance model.

  4. (Multi-)strange hadron and light (anti-)nuclei production with ALICE at the LHC

    NASA Astrophysics Data System (ADS)

    Lea, Ramona

    2016-01-01

    Thanks to its excellent tracking performance and particle identification capabilities, the ALICE detector allows for the identification of light (anti-)(hyper)nuclei and for the measurement of (multi-)strange particles over a wide range of transverse momentum. Deuterons, 3He and 4He and their corresponding anti-nuclei are identified via their specific energy loss in the Time Projection Chamber and the velocity measurement provided by the Time-Of-Flight detector. Strange and multi-strange baryons and mesons as well as (anti-)hypertritons are reconstructed via their topological decays. Detailed measurements of (multi-)strange hadron production in pp, p-Pb and Pb-Pb collision and of light (anti-)nuclei and (anti-)hypertritons in Pb-Pb collisions with ALICE at the LHC are presented. The experimental results will be compared with the predictions of both statistical hadronization and coalescence models.

  5. Calculation of the total electron excitation cross section in the Born approximation using Slater wave functions for the Li (2s yields 2p), Li (2s yields 3p), Na (3s yields 4p), Mg (3p yields 4s), Ca (4s yields 4p) and K (4s yields 4p) excitations. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Simsic, P. L.

    1974-01-01

    Excitation of neutral atoms by inelastic scattering of incident electrons in gaseous nebulae were investigated using Slater Wave functions to describe the initial and final states of the atom. Total cross sections using the Born Approximation are calculated for: Li(2s yields 2p), Na(3s yields 4p), k(4s yields 4p). The intensity of emitted radiation from gaseous nebulae is also calculated, and Maxwell distribution is employed to average the kinetic energy of electrons.

  6. Spin down of rotating compact magnetized strange stars in general relativity

    NASA Astrophysics Data System (ADS)

    Abdujabbarov, Ahmadjon

    2016-07-01

    We find that in general relativity slow down of the pulsar rotation due to the magnetodipolar radiation is more faster for the strange star with comparison to that for the ordinary neutron star of the same mass. Comparison with astrophysical observations on pulsars spindown data may provide an evidence for the strange star existence and, thus, serve as a test for distinguishing it from the neutron star.

  7. Simulation of electromagnetic and strange probes of dense nuclear matter at NICA/MPD

    NASA Astrophysics Data System (ADS)

    Zinchenko, A.; Kolesnikov, V.; Vasendina, V.

    2016-01-01

    The main task of the NICA/MPD physics program is a study of the properties of nuclear matter under extreme conditions achieved in collisions of heavy ions. These properties can reveal themselves through different probes, the most promising among those being the lepton-antilepton pairs and strange hadrons. In this paper the MPD performance for measuring the electron-positron pairs and strange hyperons in central Au+Au collisions at NICA energies is presented.

  8. Harmonically excited orbital variations

    SciTech Connect

    Morgan, T.

    1985-08-06

    Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.

  9. New upper limit on strange quark matter abundance in cosmic rays with the PAMELA space experiment.

    PubMed

    Adriani, O; Barbarino, G C; Bazilevskaya, G A; Bellotti, R; Boezio, M; Bogomolov, E A; Bongi, M; Bonvicini, V; Bottai, S; Bruno, A; Cafagna, F; Campana, D; Carlson, P; Casolino, M; Castellini, G; De Donato, C; De Santis, C; De Simone, N; Di Felice, V; Formato, V; Galper, A M; Karelin, A V; Koldashov, S V; Koldobskiy, S; Krutkov, S Y; Kvashnin, A N; Leonov, A; Malakhov, V; Marcelli, L; Martucci, M; Mayorov, A G; Menn, W; Mergè, M; Mikhailov, V V; Mocchiutti, E; Monaco, A; Mori, N; Munini, R; Osteria, G; Palma, F; Panico, B; Papini, P; Pearce, M; Picozza, P; Ricci, M; Ricciarini, S B; Sarkar, R; Scotti, V; Simon, M; Sparvoli, R; Spillantini, P; Stozhkov, Y I; Vacchi, A; Vannuccini, E; Vasilyev, G; Voronov, S A; Yurkin, Y T; Zampa, G; Zampa, N

    2015-09-11

    In this work we present results of a direct search for strange quark matter (SQM) in cosmic rays with the PAMELA space spectrometer. If this state of matter exists it may be present in cosmic rays as particles, called strangelets, having a high density and an anomalously high mass-to-charge (A/Z) ratio. A direct search in space is complementary to those from ground-based spectrometers. Furthermore, it has the advantage of being potentially capable of directly identifying these particles, without any assumption on their interaction model with Earth's atmosphere and the long-term stability in terrestrial and lunar rocks. In the rigidity range from 1.0 to ∼1.0×10^{3}  GV, no such particles were found in the data collected by PAMELA between 2006 and 2009. An upper limit on the strangelet flux in cosmic rays was therefore set for particles with charge 1≤Z≤8 and mass 4≤A≤1.2×10^{5}. This limit as a function of mass and as a function of magnetic rigidity allows us to constrain models of SQM production and propagation in the Galaxy. PMID:26406816

  10. Toward the excited isoscalar meson spectrum from lattice QCD

    SciTech Connect

    Dudek, Jozef J.; Edwards, Robert G.; Guo, Peng; Thomas, Christopher E.

    2013-11-18

    We report on the extraction of an excited spectrum of isoscalar mesons using lattice QCD. Calculations on several lattice volumes are performed with a range of light quark masses corresponding to pion masses down to about ~400 MeV. The distillation method enables us to evaluate the required disconnected contributions with high statistical precision for a large number of meson interpolating fields. We find relatively little mixing between light and strange in most JPC channels; one notable exception is the pseudoscalar sector where the approximate SU(3)F octet, singlet structure of the η, η' is reproduced. We extract exotic JPC states, identified as hybrid mesons in which an excited gluonic field is coupled to a color-octet qqbar pair, along with non-exotic hybrid mesons embedded in a qq¯-like spectrum.

  11. Toward the excited isoscalar meson spectrum from lattice QCD

    DOE PAGESBeta

    Dudek, Jozef J.; Edwards, Robert G.; Guo, Peng; Thomas, Christopher E.

    2013-11-18

    We report on the extraction of an excited spectrum of isoscalar mesons using lattice QCD. Calculations on several lattice volumes are performed with a range of light quark masses corresponding to pion masses down to about ~400 MeV. The distillation method enables us to evaluate the required disconnected contributions with high statistical precision for a large number of meson interpolating fields. We find relatively little mixing between light and strange in most JPC channels; one notable exception is the pseudoscalar sector where the approximate SU(3)F octet, singlet structure of the η, η' is reproduced. We extract exotic JPC states, identifiedmore » as hybrid mesons in which an excited gluonic field is coupled to a color-octet qqbar pair, along with non-exotic hybrid mesons embedded in a qq¯-like spectrum.« less

  12. Semileptonic B and Bs decays into orbitally excited charmed mesons

    NASA Astrophysics Data System (ADS)

    Segovia, J.; Albertus, C.; Entem, D. R.; Fernández, F.; Hernández, E.; Pérez-García, M. A.

    2011-11-01

    The BABAR Collaboration has recently reported products of branching fractions that include B meson semileptonic decays into final states with charged and neutral D1(2420) and D2*(2460), two narrow orbitally excited charmed mesons. We evaluate these branching fractions, together with those concerning D0*(2400) and D1'(2430) mesons, within the framework of a constituent quark model. The calculation is performed in two steps, one of which involves a semileptonic decay and the other is mediated by a strong process. Our results are in agreement with the experimental data. We also extend the study to semileptonic decays of Bs into orbitally excited charmed-strange mesons, providing predictions to the possible measurements to be carried out at LHC.

  13. [Ambient modulation of neuronal excitability].

    PubMed

    Chen, Yi-Zhang

    2016-08-25

    Although the modulation of synaptic activity plays an important role in the modulation of neuronal excitability, the significance of the ambient modulation (AM) of neuronal excitability should be emphasized. The AM refers to the alterations of membrane potential of neuron resulted from distinct neural activities, such as the tonic inhibition and excitation through activation of extra-synaptic receptors, the paracrine actions of nearby neural and non-neural cells, endocrinal actions of blood borne hormones and other active chemical substances. The AM of neuronal excitability may have important bearings on distinct brain functions, such as the regulation and switching of cortical states, the appearance of chaotic and vague feelings, which are usually the characteristic features in many mental and neural disorders. PMID:27546499

  14. Fission-fragment angular distributions and excitation functions in fission following complete fusion and targetlike-fragment fission reactions of 19F+232Th at near- and sub-barrier energies

    NASA Astrophysics Data System (ADS)

    Majumdar, N.; Bhattacharya, P.; Biswas, D. C.; Choudhury, R. K.; Nadkarni, D. M.; Saxena, A.

    1995-06-01

    The fragment angular distributions and excitation functions of the fission following complete fusion (FFCF) have been measured after separating them from targetlike-fragment fission (TLFF) for the 19F+232Th system in the bombarding energy range of 84.5 to 106.5 MeV. The fraction of the targetlike-fragment fission was observed to increase with decreasing bombarding energy below the Coulomb barrier. The excitation function for fission following complete fusion reaction agrees well with coupled channel calculations. However, the values derived from the fragment anisotropy data of the FFCF events are found to be much larger than those calculated using the coupled channel transmission coefficient values. The discrepancy between the experimental and calculated values increases as the bombarding energy is decreased below the barrier.

  15. Electron impact excitation cross sections for carbon

    NASA Astrophysics Data System (ADS)

    Ganas, P. S.

    1981-04-01

    A realistic analytic atomic independent particle model is used to generate wave functions for the valence and excited states of carbon. Using these wave functions in conjunction with the Born approximation and the Russell-Saunders LS-coupling scheme, we calculate generalized oscillator strengths and integrated cross sections for various excitations from the 2p 2( 3P O) valence state.

  16. Strangeness in neutron star matter: a challenging puzzle

    NASA Astrophysics Data System (ADS)

    Lonardoni, Diego; Lovato, Alessandro; Gandolfi, Stefano; Pederiva, Francesco

    2014-09-01

    The onset of strange baryons in the core of neutron stars and the consequent softening of the equation of state have been questioned for a long time. Controversial theoretical predictions about the predicted maximum mass and the recent astrophysical observations are the grounds of the so called hyperon puzzle. We attempt to give our contribution to the discussion by studying the general problem of the hyperon-nucleon interaction by means of Auxiliary Field Diffusion Monte Carlo calculations. We employ a phenomenological approach showing that a three-body hyperon-nucleon force provides the strong repulsive contribution needed to correctly describe the systematics of medium-light Λ hypernuclei. The same potential has been used to determine the equation of state and the mass-radius relation of an infinite systems of neutrons and Λ particles. We find that the three-body hyperon-nucleon force has a dramatic effect on the equation of state and the predicted maximum mass. Our results suggest that more constraints on the nature of hyperon-neutron forces are needed before drawing any conclusion on the role played by hyperons in neutron stars. The onset of strange baryons in the core of neutron stars and the consequent softening of the equation of state have been questioned for a long time. Controversial theoretical predictions about the predicted maximum mass and the recent astrophysical observations are the grounds of the so called hyperon puzzle. We attempt to give our contribution to the discussion by studying the general problem of the hyperon-nucleon interaction by means of Auxiliary Field Diffusion Monte Carlo calculations. We employ a phenomenological approach showing that a three-body hyperon-nucleon force provides the strong repulsive contribution needed to correctly describe the systematics of medium-light Λ hypernuclei. The same potential has been used to determine the equation of state and the mass-radius relation of an infinite systems of neutrons and

  17. PREFACE: SQM2007 International Conference on Strangeness in Quark Matter

    NASA Astrophysics Data System (ADS)

    Šafařík, Karel; Šándor, Ladislav; Tomášik, Boris

    2008-04-01

    The International Conference on `Strangeness in Quark Matter' (SQM) was held from 24-29 June 2007 at the Congress Hall of the city cultural centre in the charming mediaeval town of Levoča in north-eastern Slovakia. The Institute of Experimental Physics of the Slovak Academy of Science and the Faculty of Science of the P J Šafárik University in Košice shared the duties of main organizers of the conference. SQM2007 was attended by more than 100 participants from about 20 countries. The natural beauty and the rich cultural and historical monuments of the surrounding Spiš (Scepusium) region created an inspiring setting for the scientific, social and cultural framework of the conference. Continuing the trend started at the SQM2006 conference, heavy flavour physics in heavy-ion collisions was a topic given equal importance in the SQM2007 programme alongside strange quark physics. The Symposium for Students, from Students, organized by Christian Klein-Boesing and Boris Tomášik on the basis of the contributed abstracts, was again an integral and successful part of the conference. The jury, drawn from the organizers, awarded William A Horowitz (Columbia University) the title of best student contribution. The good news is that many students and younger researchers attended the conference. This could not have happened without generous support from our sponsors whom we would like to thank for valuable financial support: CERN, Journal of Physics G, the Prešov self-governing region authorities and the Slovak Physical Society. The kind assistance of the mayor of the town of Levoča is also warmly acknowledged. We would like to extend our gratitude to our colleagues and students from the organizing institutions for their diligent work prior to and during the conference, which ensured that everything worked smoothly. Our special thanks go to our secretaries, Adri Chomičová and Mery Šemš'aková, as well as to the management of the SATEL Hotel in Levoča for their highly

  18. Circadian regulation of human cortical excitability.

    PubMed

    Ly, Julien Q M; Gaggioni, Giulia; Chellappa, Sarah L; Papachilleos, Soterios; Brzozowski, Alexandre; Borsu, Chloé; Rosanova, Mario; Sarasso, Simone; Middleton, Benita; Luxen, André; Archer, Simon N; Phillips, Christophe; Dijk, Derk-Jan; Maquet, Pierre; Massimini, Marcello; Vandewalle, Gilles

    2016-01-01

    Prolonged wakefulness alters cortical excitability, which is essential for proper brain function and cognition. However, besides prior wakefulness, brain function and cognition are also affected by circadian rhythmicity. Whether the regulation of cognition involves a circadian impact on cortical excitability is unknown. Here, we assessed cortical excitability from scalp electroencephalography (EEG) responses to transcranial magnetic stimulation in 22 participants during 29 h of wakefulness under constant conditions. Data reveal robust circadian dynamics of cortical excitability that are strongest in those individuals with highest endocrine markers of circadian amplitude. In addition, the time course of cortical excitability correlates with changes in EEG synchronization and cognitive performance. These results demonstrate that the crucial factor for cortical excitability, and basic brain function in general, is the balance between circadian rhythmicity and sleep need, rather than sleep homoeostasis alone. These findings have implications for clinical applications such as non-invasive brain stimulation in neurorehabilitation. PMID:27339884

  19. Circadian regulation of human cortical excitability

    PubMed Central

    Ly, Julien Q. M.; Gaggioni, Giulia; Chellappa, Sarah L.; Papachilleos, Soterios; Brzozowski, Alexandre; Borsu, Chloé; Rosanova, Mario; Sarasso, Simone; Middleton, Benita; Luxen, André; Archer, Simon N.; Phillips, Christophe; Dijk, Derk-Jan; Maquet, Pierre; Massimini, Marcello; Vandewalle, Gilles

    2016-01-01

    Prolonged wakefulness alters cortical excitability, which is essential for proper brain function and cognition. However, besides prior wakefulness, brain function and cognition are also affected by circadian rhythmicity. Whether the regulation of cognition involves a circadian impact on cortical excitability is unknown. Here, we assessed cortical excitability from scalp electroencephalography (EEG) responses to transcranial magnetic stimulation in 22 participants during 29 h of wakefulness under constant conditions. Data reveal robust circadian dynamics of cortical excitability that are strongest in those individuals with highest endocrine markers of circadian amplitude. In addition, the time course of cortical excitability correlates with changes in EEG synchronization and cognitive performance. These results demonstrate that the crucial factor for cortical excitability, and basic brain function in general, is the balance between circadian rhythmicity and sleep need, rather than sleep homoeostasis alone. These findings have implications for clinical applications such as non-invasive brain stimulation in neurorehabilitation. PMID:27339884

  20. The Strange-Antistrange Asymmetry, The NuTeV Measurement and a Peek at Future Prospects.

    SciTech Connect

    Mason, D.

    2007-12-21

    The strange asymmetry measurement from NuTeV is discussed, followed by a brief look at measurement prospects from other current and future neutrino DIS experiments. The NuTeV measurement of the difference between the strange and antistrange quark distributions from dimuon events utilizes the first complete NLO QCD description of the process. Dimuon events, resulting from the semi-muonic decay of charmed particles produced in charged current neutrino interactions, allow direct study of the strange quark content of the nucleon. NuTeV's sign selected beam produced uniquely pure samples of neutrino and antineutrino initiated dimuon events, allowing independent measurement of the strange and antistrange quark distributions.