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Sample records for bidirectional dynamic nuclear

  1. Bottleneck effects on the bidirectional crowd dynamics

    Science.gov (United States)

    Yang, Xiao-Xia; Dong, Hai-Rong; Yao, Xiu-Ming; Sun, Xu-Bin

    2016-12-01

    The bottleneck effect on bidirectional crowd dynamics is of great theoretical and practical significance, especially for the designing of corridors in public places, such as subway stations or airports. Based on the famous social force model, this paper investigates the bottleneck effects on the free flow dynamics and breakdown phenomenon under different scenarios, in which different corridor shapes and inflow ratios are considered simultaneously. Numerical simulation finds an interesting self-organization phenomenon in the bidirectional flow, a typical characteristic of such a phenomenon is called lane formation, and the existence of which is independent of the corridor’s shape and inflow rate. However, the pattern of the lane formed by pedestrian flow is related to the corridor’s shape, and the free flow efficiency has close relationship with the inflow rate. Specifically, breakdown phenomenon occurs when inflows from both sides of the corridor are large enough, which mostly originates from the bottleneck and then gradually spreads to the other regions. Simulation results further indicate that the leaving efficiency becomes low as breakdown occurs, and the degree of congestion is proportional to the magnitude of inflow. The findings presented in this paper match well with some of our daily observations, hence it is possible to use them to provide us with theoretical suggestions in design of infrastructures. Project supported jointly by the National Natural Science Foundation of China (Grant Nos. 61322307 and 2016YJS023).

  2. Bidirectional ROF Links with Dynamic Capacity Allocation

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar Chandan , Dharmendra Singh

    2013-10-01

    Full Text Available : Radio over fiber (ROF technology is an integration of wireless and fiber optic network. It plays vital role for broad band wireless communication. The well known advantages of optical as a transmission medium such as low loss, light weight, large bandwidth characteristics, small size and low cable cost make it the ideal and most flexible solution for efficiently transporting radio signals to remotely located antenna site in a wireless network. The joint venture of radio signal and optical fiber technology provides dynamic capacity allocation in radio over fiber links.

  3. Bidirectional Dynamic Diversity Evolutionary Algorithm for Constrained Optimization

    Directory of Open Access Journals (Sweden)

    Weishang Gao

    2013-01-01

    Full Text Available Evolutionary algorithms (EAs were shown to be effective for complex constrained optimization problems. However, inflexible exploration-exploitation and improper penalty in EAs with penalty function would lead to losing the global optimum nearby or on the constrained boundary. To determine an appropriate penalty coefficient is also difficult in most studies. In this paper, we propose a bidirectional dynamic diversity evolutionary algorithm (Bi-DDEA with multiagents guiding exploration-exploitation through local extrema to the global optimum in suitable steps. In Bi-DDEA potential advantage is detected by three kinds of agents. The scale and the density of agents will change dynamically according to the emerging of potential optimal area, which play an important role of flexible exploration-exploitation. Meanwhile, a novel double optimum estimation strategy with objective fitness and penalty fitness is suggested to compute, respectively, the dominance trend of agents in feasible region and forbidden region. This bidirectional evolving with multiagents can not only effectively avoid the problem of determining penalty coefficient but also quickly converge to the global optimum nearby or on the constrained boundary. By examining the rapidity and veracity of Bi-DDEA across benchmark functions, the proposed method is shown to be effective.

  4. Dynamic nuclear spin polarization

    Energy Technology Data Exchange (ETDEWEB)

    Stuhrmann, H.B. [GKSS-Forschungszentrum Geesthacht GmbH (Germany)

    1996-11-01

    Polarized neutron scattering from dynamic polarized targets has been applied to various hydrogenous materials at different laboratories. In situ structures of macromolecular components have been determined by nuclear spin contrast variation with an unprecedented precision. The experiments of selective nuclear spin depolarisation not only opened a new dimension to structural studies but also revealed phenomena related to propagation of nuclear spin polarization and the interplay of nuclear polarisation with the electronic spin system. The observation of electron spin label dependent nuclear spin polarisation domains by NMR and polarized neutron scattering opens a way to generalize the method of nuclear spin contrast variation and most importantly it avoids precontrasting by specific deuteration. It also likely might tell us more about the mechanism of dynamic nuclear spin polarisation. (author) 4 figs., refs.

  5. GLOBAL DYNAMICS OF DELAYED BIDIRECTIONAL ASSOCIATIVE MEMORY (BAM) NEURAL NETWORKS

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jin; LIU Zeng-rong; XIANG Lan

    2005-01-01

    Without assuming the smoothness, monotonicity and boundedness of the activation functions, some novel criteria on the existence and global exponential stability of equilibrium point for delayed bidirectional associative memory (BAM) neural networks are established by applying the Liapunov functional methods and matrix-algebraic techniques. It is shown that the new conditions presented in terms of a nonsingular M matrix described by the networks parameters, the connection matrix and the Lipschitz constant of the activation functions, are not only simple and practical, but also easier to check and less conservative than those imposed by similar results in recent literature.

  6. A possible mechanism for self coordination of bi-directional traffic across nuclear pores

    CERN Document Server

    Kapon, Ruti; Mukamel, David; Reich, and Ziv

    2008-01-01

    Nuclear pore complexes are constantly confronted by large fluxes of macromolecules and macromolecular complexes that need to get into and out of the nucleus. Such bi-directional traffic occurring in a narrow channel can easily lead to jamming. How then is passage between the nucleus and cytoplasm maintained under the varying conditions that arise during the lifetime of the cell? Here, we address this question using computer simulations in which the behaviour of the ensemble of transporting cargoes is analyzed under different conditions. We suggest that traffic can exist in two distinct modes, depending on concentration of cargoes and dissociation rates of the transport receptor-cargo complexes from the pores. In one mode, which prevails when dissociation is quick and cargo concentration is low, transport in either direction proceeds uninterrupted by the other direction. The result is that overall-traffic-direction fluctuates rapidly and unsystematically between import and export. Remarkably, when cargo concen...

  7. Bidirectional control of the inner dynamics of focal adhesions promotes cell migration

    OpenAIRE

    2009-01-01

    Focal adhesions (FA) are bidirectional mechanical biosensors that allow cells to integrate intracellular and extracellular cues. Their function is tightly regulated by changes in molecular composition and also by variation in the spatio-temporal dynamics of FA components within this structure. A closely regulated turnover of FA proteins within FA sites allows cells to respond appropriately to their environment, thereby impacting on cell shape and function. FA protein dynamics are linked to FA...

  8. High-Fidelity Bidirectional Nuclear Qubit Initialization in SiC

    Science.gov (United States)

    Ivády, Viktor; Klimov, Paul V.; Miao, Kevin C.; Falk, Abram L.; Christle, David J.; Szász, Krisztián; Abrikosov, Igor A.; Awschalom, David D.; Gali, Adam

    2016-11-01

    Dynamic nuclear polarization (DNP) is an attractive method for initializing nuclear spins that are strongly coupled to optically active electron spins because it functions at room temperature and does not require strong magnetic fields. In this Letter, we theoretically demonstrate that DNP, with near-unity polarization efficiency, can be generally realized in weakly coupled electron spin-nuclear spin systems. Furthermore, we theoretically and experimentally show that the nuclear spin polarization can be reversed by magnetic field variations as small as 0.8 Gauss. This mechanism offers new avenues for DNP-based sensors and radio-frequency free control of nuclear qubits.

  9. Coupling strength versus coupling impact in nonidentical bidirectionally coupled dynamics

    Science.gov (United States)

    Laiou, Petroula; Andrzejak, Ralph G.

    2017-01-01

    The understanding of interacting dynamics is important for the characterization of real-world networks. In general, real-world networks are heterogeneous in the sense that each node of the network is a dynamics with different properties. For coupled nonidentical dynamics symmetric interactions are not straightforwardly defined from the coupling strength values. Thus, a challenging issue is whether we can define a symmetric interaction in this asymmetric setting. To address this problem we introduce the notion of the coupling impact. The coupling impact considers not only the coupling strength but also the energy of the individual dynamics, which is conveyed via the coupling. To illustrate this concept, we follow a data-driven approach by analyzing signals from pairs of coupled model dynamics using two different connectivity measures. We find that the coupling impact, but not the coupling strength, correctly detects a symmetric interaction between pairs of coupled dynamics regardless of their degree of asymmetry. Therefore, this approach allows us to reveal the real impact that one dynamics has on the other and hence to define symmetric interactions in pairs of nonidentical dynamics.

  10. A bidirectional brain-machine interface connecting alert rodents to a dynamical system.

    Science.gov (United States)

    Boi, Fabio; Semprini, Marianna; Mussa Ivaldi, Ferdinando A; Panzeri, Stefano; Vato, Alessandro

    2015-01-01

    We present a novel experimental framework that implements a bidirectional brain-machine interface inspired by the operation of the spinal cord in vertebrates that generates a control policy in the form of a force field. The proposed experimental set-up allows connecting the brain of freely moving rats to an external device. We tested this apparatus in a preliminary experiment with an alert rat that used the interface for acquiring a food reward. The goal of this approach to bidirectional interfaces is to explore the role of voluntary neural commands in controlling a dynamical system represented by a small cart moving on vertical plane and connected to a water/pellet dispenser.

  11. Chiral Nuclear Dynamics II

    CERN Document Server

    Rho, Mannque

    2008-01-01

    This is the sequel to the first volume to treat in one effective field theory framework the physics of strongly interacting matter under extreme conditions. This is vital for understanding the high temperature phenomena taking place in relativistic heavy ion collisions and in the early Universe, as well as the high-density matter predicted to be present in compact stars. The underlying thesis is that what governs hadronic properties in a heat bath and/or a dense medium is hidden local symmetry which emerges from chiral dynamics of light quark systems and from the duality between QCD in 4D and

  12. DMS AND 13C NMR STUDIES ON THE COMPATIBILITY AND DYNAMICS OF LATEX BIDIRECTIONAL IPNS AND LATEX IPN OF PVA c/PBA

    Institute of Scientific and Technical Information of China (English)

    YAN Xin; XU Xiaolong; ZHANG Baozhen; YAO Shuren; QIAN Baogong

    1993-01-01

    The compatibility and dynamics of latex bidirectional interpenetrating polymer networks (LBIPNs) and latex IPN(LIPN) of poly(vinyl acetate)(PVAc) and poly (butyl acrylate )(PBA) are investigated by means of dynamic mechanical spectroscopy (DMS) and nuclear magnetic resonance (NMR) techniques. The results of DMS show that the compatibility of the LBIPNs is much better than that of the corresponding LIPN and depends to a large extent on the distribution of PVAc both in the core and in the shell. The results of NMR measurements indicate that the rotational correlation times of the side- groups of PBA in the LBIPN are longer than those in the LIPN. The relation between the 13C linewidths of PBA and temperature is also discussed.

  13. Nuclear chiral dynamics and thermodynamics

    Science.gov (United States)

    Holt, Jeremy W.; Kaiser, Norbert; Weise, Wolfram

    2013-11-01

    This presentation reviews an approach to nuclear many-body systems based on the spontaneously broken chiral symmetry of low-energy QCD. In the low-energy limit, for energies and momenta small compared to a characteristic symmetry breaking scale of order 1 GeV, QCD is realized as an effective field theory of Goldstone bosons (pions) coupled to heavy fermionic sources (nucleons). Nuclear forces at long and intermediate distance scales result from a systematic hierarchy of one- and two-pion exchange processes in combination with Pauli blocking effects in the nuclear medium. Short distance dynamics, not resolved at the wavelengths corresponding to typical nuclear Fermi momenta, are introduced as contact interactions between nucleons. Apart from a set of low-energy constants associated with these contact terms, the parameters of this theory are entirely determined by pion properties and low-energy pion-nucleon scattering observables. This framework (in-medium chiral perturbation theory) can provide a realistic description of both isospin-symmetric nuclear matter and neutron matter, with emphasis on the isospin-dependence determined by the underlying chiral NN interaction. The importance of three-body forces is emphasized, and the role of explicit Δ(1232)-isobar degrees of freedom is investigated in detail. Nuclear chiral thermodynamics is developed and a calculation of the nuclear phase diagram is performed. This includes a successful description of the first-order phase transition from a nuclear Fermi liquid to an interacting Fermi gas and the coexistence of these phases below a critical temperature Tc. Density functional methods for finite nuclei based on this approach are also discussed. Effective interactions, their density dependence and connections to Landau Fermi liquid theory are outlined. Finally, the density and temperature dependences of the chiral (quark) condensate are investigated.

  14. Dynamical features of nuclear fission

    Indian Academy of Sciences (India)

    Santanu Pal

    2015-08-01

    It is now established that the transition-state theory of nuclear fission due to Bohr and Wheeler underestimates several observables in heavy-ion-induced fusion–fission reactions. Dissipative dynamical models employing either the Langevin equation or equivalently the Fokker–Planck equation have been developed for fission of heavy nuclei at high excitations (T ∼1 MeV or higher). Here, we first present the physical picture underlying the dissipative fission dynamics. We mainly concentrate upon the Kramers’ prescription for including dissipation in fission dynamics. We discuss, in some detail, the results of a statistical model analysis of the pre-scission neutron multiplicity data from the reactions 19F+194,196,198Pt using Kramers’ fission width. We also discuss the multi-dimensional Langevin equation in the context of kinetic energy and mass distribution of the fission fragments.

  15. Nuclear chiral dynamics and thermodynamics

    CERN Document Server

    Holt, J W; Weise, W

    2013-01-01

    This presentation reviews an approach to nuclear many-body systems based on the spontaneously broken chiral symmetry of low-energy QCD. In the low-energy limit, for energies and momenta small compared to a characteristic symmetry breaking scale of order 1 GeV, QCD is realized as an effective field theory of Goldstone bosons (pions) coupled to heavy fermionic sources (nucleons). Nuclear forces at long and intermediate distance scales result from a systematic hierarchy of one- and two-pion exchange processes in combination with Pauli blocking effects in the nuclear medium. Short distance dynamics, not resolved at the wavelengths corresponding to typical nuclear Fermi momenta, are introduced as contact interactions between nucleons. Apart from a set of low-energy constants associated with these contact terms, the parameters of this theory are entirely determined by pion properties and low-energy pion-nucleon scattering observables. This framework (in-medium chiral perturbation theory) can provide a realistic des...

  16. Semiclassical approaches to nuclear dynamics

    CERN Document Server

    Magner, A G; Bartel, J

    2016-01-01

    The extended Gutzwiller trajectory approach is presented for the semiclassical description of nuclear collective dynamics, in line with the main topics of the fruitful activity of V.G. Solovjov. Within the Fermi-liquid droplet model, the leptodermous effective surface approximation was applied to calculations of energies, sum rules and transition densities for the neutron-proton asymmetry of the isovector giant-dipole resonance and found to be in good agreement with the experimental data. By using the Strutinsky shell correction method, the semiclassical collective transport coefficients such as nuclear inertia, friction, stiffness, and moments of inertia can be derived beyond the quantum perturbation approximation of the response function theory and the cranking model.The averaged particle-number dependence of the low-lying collective vibrational states are described in good agreement with basic experimental data, mainly due to an enhancement of the collective inertia as compared to its irrotational flow val...

  17. Bidirectional coupling between astrocytes and neurons mediates learning and dynamic coordination in the brain: a multiple modeling approach.

    Directory of Open Access Journals (Sweden)

    John J Wade

    Full Text Available In recent years research suggests that astrocyte networks, in addition to nutrient and waste processing functions, regulate both structural and synaptic plasticity. To understand the biological mechanisms that underpin such plasticity requires the development of cell level models that capture the mutual interaction between astrocytes and neurons. This paper presents a detailed model of bidirectional signaling between astrocytes and neurons (the astrocyte-neuron model or AN model which yields new insights into the computational role of astrocyte-neuronal coupling. From a set of modeling studies we demonstrate two significant findings. Firstly, that spatial signaling via astrocytes can relay a "learning signal" to remote synaptic sites. Results show that slow inward currents cause synchronized postsynaptic activity in remote neurons and subsequently allow Spike-Timing-Dependent Plasticity based learning to occur at the associated synapses. Secondly, that bidirectional communication between neurons and astrocytes underpins dynamic coordination between neuron clusters. Although our composite AN model is presently applied to simplified neural structures and limited to coordination between localized neurons, the principle (which embodies structural, functional and dynamic complexity, and the modeling strategy may be extended to coordination among remote neuron clusters.

  18. Nuclear Dynamics with Effective Field Theories

    CERN Document Server

    Epelbaum, Evgeny

    2013-01-01

    These are the proceedings of the international workshop on "Nuclear Dynamics with Effective Field Theories" held at Ruhr-Universitaet Bochum, Germany from July 1 to 3, 2013. The workshop focused on effective field theories of low-energy QCD, chiral perturbation theory for nuclear forces as well as few- and many-body physics. Included are a short contribution per talk.

  19. Microwave-gated dynamic nuclear polarization

    DEFF Research Database (Denmark)

    Bornet, Aurélien; Pinon, Arthur; Jhajharia, Aditya

    2016-01-01

    Dissolution dynamic nuclear polarization (D-DNP) has become a method of choice to enhance signals in nuclear magnetic resonance (NMR). Recently, we have proposed to combine cross-polarization (CP) with D-DNP to provide high polarization P((13)C) in short build-up times. In this paper, we show...

  20. Language use in real-time interactions during early elementary science lessons : The bidirectional dynamics of the language complexity of teachers and pupils

    NARCIS (Netherlands)

    Menninga, Astrid; van Dijk, Marijn; Steenbeek, Henderien; van Geert, Paul

    2016-01-01

    This study explored bidirectional sequential relations between the real-time language use of teachers and pupils in naturalistic science lessons from a dynamic approach. It also compared experienced teachers (N = 22) with relative starters (student teachers, N = 8) when it comes to such relations. V

  1. Dynamic Analyses of Isolated Structures under Bi-Directional Excitations of Near-Field Ground Motions

    Directory of Open Access Journals (Sweden)

    Gokhan Ozdemir

    2012-01-01

    Full Text Available Nonlinear response history analyses (NRHA of a 3-story isolated reinforced concrete (RC building are carried out under both uni- and bi-directional earthquake excitations of near-field records. NRHA are conducted for a wide range of yield strength (Q/W of lead rubber bearings (LRB, and isolation period (T. Selected near-field records are used to investigate both the contribution of orthogonal components on maximum isolator displacements and accuracy of equivalent lateral force (ELF procedure on estimation of maximum isolator displacements. Analyses results show that both the contribution of orthogonal components and accuracy of ELF procedure depend on the soil condition where isolation system is implemented.

  2. Nuclear dynamics induced by antiprotons

    CERN Document Server

    Feng, Zhao-Qing

    2015-01-01

    Reaction dynamics in collisions of antiprotons on nuclei is investigated within the Lanzhou quantum molecular dynamics model. The reaction channels of elastic scattering, annihilation, charge exchange and inelastic collisions of antiprotons on nucleons have been included in the model. Dynamics on particle production, in particular pions, kaons, antikaons and hyperons, is investigated in collisions of $\\overline{p}$ on $^{12}$C, $^{20}$Ne, $^{40}$Ca and $^{181}$Ta from a low to high incident momenta. It is found that the annihilations of $\\overline{p}$ on nucleons are of importance on the dynamics of particle production in phase space. Hyperons are mainly produced via meson induced reactions on nucleons and strangeness exchange collisions, which lead to the delayed emission in antiproton-nucleus collisions.

  3. Wavelet representation of the nuclear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Jouault, B.; Sebille, F.; Mota, V. de la

    1997-12-31

    The study of transport phenomena in nuclear matter is addressed in a new approach named DYWAN, based on the projection methods of statistical physics and on the mathematical theory of wavelets. Strongly compressed representations of the nuclear systems are obtained with an accurate description of the wave functions and of their antisymmetrization. The results of the approach are illustrated for the ground state description as well as for the dissipative dynamics of nuclei at intermediate energies. (K.A.). 52 refs.

  4. Nuclear dynamics of K¯ bound states

    Science.gov (United States)

    Mareš, J.; Friedman, E.; Gal, A.

    2006-07-01

    nuclear bound states were generated dynamically within a relativistic mean field (RMF) model. Substantial polarization of the core nucleus was found for light nuclei. The behavior of the dynamically calculated width ΓK¯ as function of the K¯ binding energy was studied. A lower limit of ΓK¯ ˜ 35 - 45 MeV for 1s K¯ nuclear states in light nuclei such as 12C was placed on the width expected for deep binding in the range B K¯ ˜ 100 - 200 MeV.

  5. Multiphase Flow Dynamics 5 Nuclear Thermal Hydraulics

    CERN Document Server

    Kolev, Nikolay Ivanov

    2012-01-01

    The present Volume 5 of the successful book package "Multiphase Flow Dynamics" is devoted to nuclear thermal hydraulics which is a substantial part of nuclear reactor safety. It provides knowledge and mathematical tools for adequate description of the process of transferring the fission heat released in materials due to nuclear reactions into its environment. It step by step introduces into the heat release inside the fuel, temperature fields in the fuels, the "simple" boiling flow in a pipe described using ideas of different complexity like equilibrium, non equilibrium, homogeneity, non homogeneity. Then the "simple" three-fluid boiling flow in a pipe is described by gradually involving the mechanisms like entrainment and deposition, dynamic fragmentation, collisions, coalescence, turbulence. All heat transfer mechanisms are introduced gradually discussing their uncertainty. Different techniques are introduced like boundary layer treatments or integral methods. Comparisons with experimental data at each step...

  6. Multiphase flow dynamics 5 nuclear thermal hydraulics

    CERN Document Server

    Kolev, Nikolay Ivanov

    2015-01-01

    This Volume 5 of the successful book package "Multiphase Flow Dynamics" is devoted to nuclear thermal hydraulics which is a substantial part of nuclear reactor safety. It provides knowledge and mathematical tools for adequate description of the process of transferring the fission heat released in materials due to nuclear reactions into its environment. It step by step introduces into the heat release inside the fuel, temperature fields in the fuels, the "simple" boiling flow in a pipe described using ideas of different complexity like equilibrium, non equilibrium, homogeneity, non homogeneity. Then the "simple" three-fluid boiling flow in a pipe is described by gradually involving the mechanisms like entrainment and deposition, dynamic fragmentation, collisions, coalescence, turbulence. All heat transfer mechanisms are introduced gradually discussing their uncertainty. Different techniques are introduced like boundary layer treatments or integral methods. Comparisons with experimental data at each step demons...

  7. Cluster dynamics transcending chemical dynamics toward nuclear fusion.

    Science.gov (United States)

    Heidenreich, Andreas; Jortner, Joshua; Last, Isidore

    2006-07-11

    Ultrafast cluster dynamics encompasses femtosecond nuclear dynamics, attosecond electron dynamics, and electron-nuclear dynamics in ultraintense laser fields (peak intensities 10(15)-10(20) W.cm(-2)). Extreme cluster multielectron ionization produces highly charged cluster ions, e.g., (C(4+)(D(+))(4))(n) and (D(+)I(22+))(n) at I(M) = 10(18) W.cm(-2), that undergo Coulomb explosion (CE) with the production of high-energy (5 keV to 1 MeV) ions, which can trigger nuclear reactions in an assembly of exploding clusters. The laser intensity and the cluster size dependence of the dynamics and energetics of CE of (D(2))(n), (HT)(n), (CD(4))(n), (DI)(n), (CD(3)I)(n), and (CH(3)I)(n) clusters were explored by electrostatic models and molecular dynamics simulations, quantifying energetic driving effects, and kinematic run-over effects. The optimization of table-top dd nuclear fusion driven by CE of deuterium containing heteroclusters is realized for light-heavy heteroclusters of the largest size, which allows for the prevalence of cluster vertical ionization at the highest intensity of the laser field. We demonstrate a 7-orders-of-magnitude enhancement of the yield of dd nuclear fusion driven by CE of light-heavy heteroclusters as compared with (D(2))(n) clusters of the same size. Prospective applications for the attainment of table-top nucleosynthesis reactions, e.g., (12)C(P,gamma)(13)N driven by CE of (CH(3)I)(n) clusters, were explored.

  8. Nuclear dynamical diffraction using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Brown, D.E.

    1993-05-01

    The scattering of synchrotron radiation by nuclei is extensively explored in this thesis. From the multipole electric field expansion resulting from time-dependent nonrelativistic perturbation theory, a dynamical scattering theory is constructed. This theory is shown, in the many particle limit, to be equivalent to the semi-classical approach where a quantum mechanical scattering amplitude is used in the Maxwell inhomogeneous wave equation. The Moessbauer specimen whose low-lying energy levels were probed is a ferromagnetic lattice of {sup 57}Fe embedded in a yttrium iron garnet (YIG) crystal matrix. The hyperfine fields in YIG thin films were studied at low and room temperature using time-resolved quantum beat spectroscopy. Nuclear hyperfine structure quantum beats were measured using a fast plastic scintillator coincidence photodetector and associated electronics having a time resolution of 2.5 nsec. The variation of the quantum beat patterns near the Bragg [0 0 2] diffraction peak gave a Lamb-Moessbauer factor of 8.2{plus_minus}0.4. Exploring characteristic dynamical features in the higher order YIG [0 0 10] reflection revealed that one of the YIG crystals had bifurcated into two different layers. The dynamics of nuclear superradiance was explored. This phenomenon includes the radiative speedup exhibited by a collective state of particles, and, in striking concurrence, resonance frequency shifts. A speedup of a factor of 4 in the total decay rate and a beat frequency shift of 1{1/2} natural resonance linewidths were observed. Nuclear resonance scattering was also found to be a useful way of performing angular interferometry experiments, and it was used to observe the phase shift of a rotated quantum state. On the whole, nuclear dynamical diffraction theory has superbly explained many of the fascinating features of resonant magnetic dipole radiation scattered by a lattice of nuclei.

  9. A method of bidirectional dynamic modeling for humanoid robot%仿人机器人的一种双向动力学建模方法

    Institute of Scientific and Technical Information of China (English)

    李国进; 易丐; 林瑜

    2011-01-01

    To obtain more accurate dynamic model of humanoid robot, this paper proposes a method of bidirectional dynamic modeling for the joints of humanoid robot. By considering of the efficiency of power transmission in two different directions, the humanoid robot was simplified as five-link mechanic structure according to the definition of ground constraint forces and joint torques. By employing the Lagrange equation, a bidirectional dynamic model of the humanoid robot was built. Compareed with the traditional modle, the results of the experiment based on SHR-6S platform and computer simulation demonstrate that this bidirectional dynamic model have a smaller error range.%为了得到更精确的仿人机器人动力学模型,提出一种在仿人机器人关节处采用双向动力学建模的方法.考虑关节处两个不同传输方向的功率传输效率,根据地面约束力和关节力矩定义,将仿人机器人简化为五连杆结构,采用Lagrange方程建立仿人机器人的双向动力学模型.对双向动力学模型进行计算机仿真,并在小型仿人机器人SHR-6S平台上进行对比实验.实验结果验证该双向动力学模型较传统方法建立的模型误差更小,更接近实测结果.

  10. Dynamic nuclear polarization in solid HD

    Energy Technology Data Exchange (ETDEWEB)

    Breuer, M. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire

    1996-12-31

    Polarized solid HD targets containing only polarizable nuclei provide the possibility to do nuclear physics experiments of overwhelming quality compared with conventional targets. Based on recent results of Solem and the experience with solid HD as a target material, an experimental setup is suggested for further investigation of dynamic polarization in HD. The influence of temperature, field, radiation dose and the concentrations of H{sub 2}, D{sub 2} and paramagnetic O{sub 2} impurities can be investigated in a systematic way. (K.A.). 18 refs.

  11. Threedimensional dynamics of nuclear decay modes

    Science.gov (United States)

    Mirea, M.; Poenaru, D. N.; Greiner, W.

    1994-03-01

    We study nondissipative fission dynamics in a wide range of mass asymmetry, covering three groups of nuclear decay modes: cluster radioactivities; alpha-decay and cold fission. The WKB action integral is calculated by using the Werner-Wheeler inertia tensor and the deformation energy within Yukawa-plus-exponential model extended to binary systems with different charge densities. The optimum dynamical trajectory in a threedimensional deformation space (elongation, necking-in and mass-asymmetry) is determined by solving a nonlinear system of differential equations. This new method is illustrated for three decay modes of234U: α-decay, Mg-radioactivity and cold fission with100Zr as a light fragment.

  12. Pulsed Dynamic Nuclear Polarization with Trityl Radicals.

    Science.gov (United States)

    Mathies, Guinevere; Jain, Sheetal; Reese, Marcel; Griffin, Robert G

    2016-01-07

    Continuous-wave (CW) dynamic nuclear polarization (DNP) is now established as a method of choice to enhance the sensitivity in a variety of NMR experiments. Nevertheless, there remains a need for the development of more efficient methods to transfer polarization from electrons to nuclei. Of particular interest are pulsed DNP methods because they enable a rapid and efficient polarization transfer that, in contrast with CW DNP methods, is not attenuated at high magnetic fields. Here we report nuclear spin orientation via electron spin-locking (NOVEL) experiments using the polarizing agent trityl OX063 in glycerol/water at a temperature of 80 K and a magnetic field of 0.34 T. (1)H NMR signal enhancements up to 430 are observed, and the buildup of the local polarization occurs in a few hundred nanoseconds. Thus, NOVEL can efficiently dynamically polarize (1)H atoms in a system that is of general interest to the solid-state DNP NMR community. This is a first, important step toward the general application of pulsed DNP at higher fields.

  13. Quantum Nuclear Extension of Electron Nuclear Dynamics on Folded Effective-Potential Surfaces

    DEFF Research Database (Denmark)

    Hall, B.; Deumens, E.; Ohrn, Y.;

    2014-01-01

    A perennial problem in quantum scattering calculations is accurate theoretical treatment of low energy collisions. We propose a method of extracting a folded, nonadiabatic, effective potential energy surface from electron nuclear dynamics (END) trajectories; we then perform nuclear wave packet...

  14. Dynamics of Nuclear Regions of Galaxies

    Science.gov (United States)

    Miller, Richard H.

    1996-01-01

    Current research carried out with the help of the ASEE-NASA Summer Faculty Program, at NASA-Ames, is concentrated on the dynamics of nuclear regions of galaxies. From a dynamical point of view a galaxy is a collection of around 10(sup 11) stars like our Sun, each of which moves in the summed gravitational field of all the remaining stars. Thus galaxy dynamics becomes a self-consistent n-body problem with forces given by Newtonian gravitation. Strong nonlinearity in the gravitational force and the inherent nonlinearity of self-consistent problems both argue for a numerical approach. The technique of numerical experiments consis of constructing an environment in the computer that is as close as possible to the physical conditions in a real galaxy and then carrying out experiments much like laboratory experiments in physics or engineering, in this environment. Computationally, an experiment is an initial value problem, and a good deal of thought and effort goes into the design of the starting conditions that serve as initial values. Experiments are run at Ames because all the 'equipment' is in place-the programs, the necessary computational power, and good facilities for post-run analysis. Our goal for this research program is to study the nuclear regions in detail and this means replacing most of the galaxy by a suitable boundary condition to allow the full capability of numerical experiments to be brought to bear on a small region perhaps 1/1000 of the linear dimensions of an entire galaxy. This is an extremely delicate numerical problem, one in which some small feature overlook, can easily lead to a collapse or blow-up of the entire system. All particles attract each other in gravitational problems, and the 1/r(sup 2) force is: (1) nonlinear; (2) strong at short range; (3) long-range, and (4) unscreened at any distance.

  15. Development on dynamic nuclear polarized targets

    CERN Document Server

    Penttila, S I

    2002-01-01

    Our interest in understanding the spin content of the nucleon has left its marks on the recent development of the dynamic nuclear polarized (DNP) targets. This can be seen from the targets developed at CERN and SLAC for the measurement of the polarized spin structure functions in deep inelastic scattering. The results of the experiments indicated that less than 30% of the nucleon spin is carried by the quarks. This unpredicted small value initiated planning of new polarized target experiments to determine the gluon polarization on the nucleon using polarized real photons and polarized /sup 6/LiD targets. In several facilities very intense polarized photon beams are available at a wide energy range. During the next few years these photon beams with DNP targets will be used to test the fundamental GDH sum rule. Other DNP target developments are also discussed. (61 refs).

  16. Bidirectional Manchester repeater

    Science.gov (United States)

    Ferguson, J.

    1980-01-01

    Bidirectional Manchester repeater is inserted at periodic intervals along single bidirectional twisted pair transmission line to detect, amplify, and transmit bidirectional Manchester 11 code signals. Requiring only 18 TTL 7400 series IC's, some line receivers and drivers, and handful of passive components, circuit is simple and relatively inexpensive to build.

  17. Protein dynamics from nuclear magnetic relaxation.

    Science.gov (United States)

    Charlier, Cyril; Cousin, Samuel F; Ferrage, Fabien

    2016-05-01

    Nuclear magnetic resonance is a ubiquitous spectroscopic tool to explore molecules with atomic resolution. Nuclear magnetic relaxation is intimately connected to molecular motions. Many methods and models have been developed to measure and interpret the characteristic rates of nuclear magnetic relaxation in proteins. These approaches shed light on a rich and diverse range of motions covering timescales from picoseconds to seconds. Here, we introduce some of the basic concepts upon which these approaches are built and provide a series of illustrations.

  18. Bidirectional optical scattering facility

    Data.gov (United States)

    Federal Laboratory Consortium — Goniometric optical scatter instrument (GOSI)The bidirectional reflectance distribution function (BRDF) quantifies the angular distribution of light scattered from a...

  19. Bidirectional optical scattering facility

    Data.gov (United States)

    Federal Laboratory Consortium — Goniometric optical scatter instrument (GOSI) The bidirectional reflectance distribution function (BRDF) quantifies the angular distribution of light scattered from...

  20. Dynamics and Thermodynamics with Nuclear Degrees of Freedom

    CERN Document Server

    Chomaz, Philippe; Trautmann, Wolfgang; Yennello, Sherry J

    2006-01-01

    The study of nuclear reaction dynamics and thermodynamics with nuclear degrees of freedom has progressed dramatically in the past 20 years, from inclusive charge distributions to exclusive isotopically resolved fragment observables and from schematic phenomenological break-up models to sophisticated quantum many-body transport theories. A coherent and quantitative understanding of reaction mechanisms and of the underlying nuclear matter equation of state is emerging from the analysis of experimental data and from the theoretical modeling of heavy ion reactions. In addition, the accumulated evidence for phenomena related to the liquid-gas phase transition of nuclear matter has triggered interdisciplinary activities and the transfer of useful methods. In the near future, the availability of radioactive beam facilities is expected to provide unique opportunities for extending our knowledge of the dynamic properties and the nuclear phase diagram towards exotic nuclear systems with important astrophysical implicat...

  1. Theory of coherent dynamic nuclear polarization in quantum dots

    DEFF Research Database (Denmark)

    Neder, Izhar; Rudner, Mark Spencer; Halperin, Bertrand

    2014-01-01

    We consider the production of dynamic nuclear spin polarization (DNP) in a two-electron double quantum dot, in which the electronic levels are repeatedly swept through a singlet-triplet avoided crossing. Our analysis helps to elucidate the intriguing interplay between electron-nuclear hyperfine...

  2. Hyperpolarized 13C metabolic imaging using dissolution dynamic nuclear polarization

    DEFF Research Database (Denmark)

    Hurd, Ralph E.; Yen, Yi‐Fen; Chen, Albert

    2012-01-01

    This article describes the basic physics of dissolution dynamic nuclear polarization (dissolution‐DNP), and the impact of the resulting highly nonequilibrium spin states, on the physics of magnetic resonance imaging (MRI) detection. The hardware requirements for clinical translation of this techn......This article describes the basic physics of dissolution dynamic nuclear polarization (dissolution‐DNP), and the impact of the resulting highly nonequilibrium spin states, on the physics of magnetic resonance imaging (MRI) detection. The hardware requirements for clinical translation...

  3. Temporal dynamics of sand dune bidirectional reflectance characteristics for absolute radiometric calibration of optical remote sensing data

    Science.gov (United States)

    Coburn, Craig A.; Logie, Gordon; Beaver, Jason

    2016-09-01

    The use of Pseudo Invariant Calibration Sites (PICS) for establishing the radiometric trending of optical remote sensing systems has a long history of successful implementation. Past studies have shown that the PICS method is useful for evaluating the trend of sensors over time or cross-calibration of sensors but was not considered until recently for deriving absolute calibration. Current interest in using this approach to establish absolute radiometric calibration stems from recent research that indicates that with empirically derived models of the surface properties and careful atmospheric characterisation Top of Atmosphere (TOA) reflectance values can be predicted and used for absolute sensor radiometric calibration. Critical to the continued development of this approach is the accurate characterization of the Bidirectional Reflectance Distribution Function (BRDF) of PICS sites. This paper presents BRDF data collected by a high-performance portable goniometer system in order to develop a temporal BRDF model for the Algodones Dunes in California. The results demonstrated that the BRDF of a reasonably simple sand surface was complex with changes in anisotropy taking place in response to changing solar zenith angles. The nature of these complex interactions would present challenges to future model development.

  4. Self-Sustaining Dynamical Nuclear Polarization Oscillations in Quantum Dots

    DEFF Research Database (Denmark)

    Rudner, Mark Spencer; Levitov, Leonid

    2013-01-01

    Early experiments on spin-blockaded double quantum dots revealed robust, large-amplitude current oscillations in the presence of a static (dc) source-drain bias. Despite experimental evidence implicating dynamical nuclear polarization, the mechanism has remained a mystery. Here we introduce a min......) and nuclear spin diffusion, which governs dynamics of the spatial profile of nuclear polarization. The proposed framework naturally explains the differences in phenomenology between vertical and lateral quantum dot structures as well as the extremely long oscillation periods.......Early experiments on spin-blockaded double quantum dots revealed robust, large-amplitude current oscillations in the presence of a static (dc) source-drain bias. Despite experimental evidence implicating dynamical nuclear polarization, the mechanism has remained a mystery. Here we introduce...

  5. Dynamic nuclear polarization and nuclear magnetic resonance in the simplest pseudospin quantum Hall ferromagnet

    Science.gov (United States)

    Liu, H. W.; Yang, K. F.; Mishima, T. D.; Santos, M. B.; Hirayama, Y.

    2010-12-01

    We present dynamic nuclear polarization (DNP) in the simplest pseudospin quantum Hall ferromagnet (QHF) of an InSb two-dimensional electron gas with a large g factor using tilted magnetic fields. The DNP-induced amplitude change in a resistance spike of the QHF at large current enables observation of the resistively detected nuclear magnetic resonance of the high nuclear spin isotope I115n with nine quadrupole splittings. Our results demonstrate the importance of domain structures in the DNP process. The nuclear spin relaxation time T1 in this QHF was relatively short (˜120s) and almost temperature independent.

  6. Nuclear Dynamics at the Particle Threshold

    CERN Document Server

    Tsoneva, Nadia

    2014-01-01

    Recently, new low-energy modes of excitation called pygmy resonances have been observed. Their distinct feature is the close connection to nuclear skin oscillations. A successful description of the pygmy resonances could be achieved in a microscopic theoretical approach which incorporates the density functional theory and QRPA formalism extended with multi-phonon degrees of freedom. The latter is found of crucial importance for the understanding of the fine structure of nuclear electric and magnetic excitations at low energies. Corresponding microscopic multi-phonon response functions are implemented in the studies of s-process of nucleosynthesis.

  7. Nuclear Dynamics at the Particle Threshold

    Institute of Scientific and Technical Information of China (English)

    Nadia Tsoneva; Horst Lenske

    2015-01-01

    Recently, new low-energy modes of excitation called pygmy resonances have been observed. Their distinct feature is the close connection to nuclear skin oscillations. A successful description of the pygmy resonances could be achieved in a microscopic theoretical approach which incorporates the density functional theory and QRPA formalism extended with multi-phonon degrees of freedom. The latter is found of crucial importance for the understanding of the fine structure of nuclear electric and magnetic excitations at low energies. Corresponding microscopic multi-phonon response functions are implemented in the studies of s-process of nucleosynthesis.

  8. Partial Dynamical Symmetry in Nuclear Systems

    Energy Technology Data Exchange (ETDEWEB)

    Escher, J E

    2003-06-02

    Partial dynamical symmetry (PDS) extends and complements the concepts of exact and dynamical symmetry. It allows one to remove undesired constraints from an algebraic theory, while preserving some of the useful aspects of a dynamical symmetry, and to study the effects of symmetry breaking in a controlled manner. An example of a PDS in an interacting fermion system is presented. The associated PDS Hamiltonians are closely related with a realistic quadrupole-quadrupole interaction and provide new insights into this important interaction.

  9. New dynamic critical phenomena in nuclear and quark superfluids

    CERN Document Server

    Sogabe, Noriyuki

    2016-01-01

    We study the dynamic critical phenomena near the possible high-density QCD critical point inside the superfluid phase of nuclear and quark matter. We find that this critical point belongs to a new dynamic universality class beyond the conventional classification by Hohenberg and Halperin. We show that the speed of the superfluid phonon vanishes at the critical point and that the dynamic critical index is $z \\approx 2$.

  10. Dynamic Analysis of Nuclear Waste Generation Based on Nuclear Fuel Cycle Transition Scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, S. R. [University of Science and Technology, Daejeon (Korea, Republic of); Ko, W. I. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    According to the recommendations submitted by the Public Engagement Commission on Spent Nuclear Fuel Management (PECOS), the government was advised to pick the site for an underground laboratory and interim storage facilities before the end of 2020 followed by the related research for permanent and underground disposal of spent fuel after 10 years. In the middle of the main issues, the factors of environmentally friendly and safe way to handle nuclear waste are inextricable from nuclear power generating nation to ensure the sustainability of nuclear power. For this purposes, the closed nuclear fuel cycle has been developed regarding deep geological disposal, pyroprocessing, and burner type sodium-cooled fast reactors (SFRs) in Korea. Among two methods of an equilibrium model and a dynamic model generally used for screening nuclear fuel cycle system, the dynamic model is more appropriate to envisage country-specific environment with the transition phase in the long term and significant to estimate meaningful impacts based on the timedependent behavior of harmful wastes. This study aims at analyzing the spent nuclear fuel generation based on the long-term nuclear fuel cycle transition scenarios considered at up-to-date country specific conditions and comparing long term advantages of the developed nuclear fuel cycle option between once-through cycle and Pyro-SFR cycle. In this study, a dynamic analysis was carried out to estimate the long-term projection of nuclear electricity generation, installed capacity, spent nuclear fuel arising in different fuel cycle scenarios based on the up-to-date national energy plans.

  11. Towards a self-consistent dynamical nuclear model

    Science.gov (United States)

    Roca-Maza, X.; Niu, Y. F.; Colò, G.; Bortignon, P. F.

    2017-04-01

    Density functional theory (DFT) is a powerful and accurate tool, exploited in nuclear physics to investigate the ground-state and some of the collective properties of nuclei along the whole nuclear chart. Models based on DFT are not, however, suitable for the description of single-particle dynamics in nuclei. Following the field theoretical approach by A Bohr and B R Mottelson to describe nuclear interactions between single-particle and vibrational degrees of freedom, we have taken important steps towards the building of a microscopic dynamic nuclear model. In connection with this, one important issue that needs to be better understood is the renormalization of the effective interaction in the particle-vibration approach. One possible way to renormalize the interaction is by the so-called subtraction method. In this contribution, we will implement the subtraction method in our model for the first time and study its consequences.

  12. Quantum measurement corrections to chemically induced dynamic nuclear polarization

    CERN Document Server

    Kominis, I K

    2013-01-01

    Chemically induced dynamic nuclear polarization has emerged as a universal signature of spin order in photosynthetic reaction centers. Such polarization, significantly enhanced above thermal equilibrium, is known to result from the nuclear spin sorting inherent in the radical pair mechanism underlying long-lived charge-separated states in photosynthetic reaction centers. We will here show that the recently understood fundamental quantum dynamics of radical-ion-pair reactions open up a new and completely unexpected venue towards obtaining CIDNP signals. The fundamental decoherence mechanism inherent in the recombination process of radical pairs is shown to produce nuclear spin polarizations on the order of $10^4$ times or more higher than thermal equilibrium values at low fields relevant to natural photosynthesis in earth's magnetic field. This opens up the possibility of a fundamentally new exploration of the biological significance of high nuclear polarizations in photosynthesis.

  13. 31st Winter Workshop in Nuclear Dynamics

    CERN Document Server

    2015-01-01

    The 31st edition of the Winter Workshop will be held January 25-31st, 2015 in the Keystone Resort, Colorado, USA. As with previous years, the workshop will bring together scientists from all fields of nuclear physics for engaging and friendly exchanges of ideas. Much emphasis will be on the recent LHC and RHIC heavy ion results, but advances in the ongoing and future programs at FAIR, FRIB, NICA and JLab will also be featured.

  14. Research on Remote Network Bidirectional Detect and Control Model

    Directory of Open Access Journals (Sweden)

    Hongyao Ju

    2013-09-01

    Full Text Available Remote network bidirectional detect and control technologies are the key factors to solve local network allopatry expansibility and management. With studying gateway integration technology, bidirectional VPN technology, identity authentication technology and dynamic host management technology can be integrated into gateway. Thus, bidirectional connect and control among allopatry local networks based on Internet can be solved. Whole area expansibility of local network is realized. With experiment, the model is proved to finish remote bidirectional interconnection of local network automatically and to obtain allopatry local users authority. The equipment detecting and controlling in remote local networks are realized.  

  15. Bidirectional beam propagation method

    Science.gov (United States)

    Kaczmarski, P.; Lagasse, P. E.

    1988-05-01

    A bidirectional extension of the beam propagation method (BPM) to optical waveguides with a longitudinal discontinuity is presented. The algorithm is verified by computing a reflection of the TE(0) mode from a semiconductor laser facet. The bidirectional BPM is applicable to other configurations such as totally reflecting waveguide mirrors, an abruption transition in a waveguide, or a waveguide with many discontinuities generating multiple reflections. The method can also be adapted to TM polarization.

  16. Dynamic Systems Analysis Report for Nuclear Fuel Recycle

    Energy Technology Data Exchange (ETDEWEB)

    Brent Dixon; Sonny Kim; David Shropshire; Steven Piet; Gretchen Matthern; Bill Halsey

    2008-12-01

    This report examines the time-dependent dynamics of transitioning from the current United States (U.S.) nuclear fuel cycle where used nuclear fuel is disposed in a repository to a closed fuel cycle where the used fuel is recycled and only fission products and waste are disposed. The report is intended to help inform policy developers, decision makers, and program managers of system-level options and constraints as they guide the formulation and implementation of advanced fuel cycle development and demonstration efforts and move toward deployment of nuclear fuel recycling infrastructure.

  17. Probing electron correlation and nuclear dynamics in Momentum Space

    Energy Technology Data Exchange (ETDEWEB)

    Deleuze, M S; Hajgato, B; Morini, F; Knippenberg, S, E-mail: michael.deleuze@uhasselt.b [Research Group of Theoretical Chemistry, Department SBG, Hasselt University, Agoralaan, Gebouw D, B3590 Diepenbeek (Belgium)

    2010-02-01

    Orbital imaging experiments employing Electron Momentum Spectroscopy are subject to many complications, such as distorted wave effects, conformational mobility in the electronic ground state, ultra-fast nuclear dynamics in the final state, or a dispersion of the ionization intensity over electronically excited (shake-up) configurations of the cation. The purpose of the present contribution is to illustrate how a proper treatment of these complications enables us to probe in momentum space the consequences of electron correlation and nuclear dynamics in neutral and cationic states.

  18. Fluctuations and symmetry energy in nuclear fragmentation dynamics.

    Science.gov (United States)

    Colonna, M

    2013-01-25

    Within a dynamical description of nuclear fragmentation, based on the liquid-gas phase transition scenario, we explore the relation between neutron-proton density fluctuations and nuclear symmetry energy. We show that, along the fragmentation path, isovector fluctuations follow the evolution of the local density and approach an equilibrium value connected to the local symmetry energy. Higher-density regions are characterized by smaller average asymmetry and narrower isotopic distributions. This dynamical analysis points out that fragment final state isospin fluctuations can probe the symmetry energy of the density domains from which fragments originate.

  19. Dissolution Dynamic Nuclear Polarization capability study with fluid path

    DEFF Research Database (Denmark)

    Malinowski, Ronja Maja; Lipsø, Hans Kasper Wigh; Lerche, Mathilde Hauge

    2016-01-01

    Signal enhancement by hyperpolarization is a way of overcoming the low sensitivity in magnetic resonance; MRI in particular. One of the most well-known methods, dissolution Dynamic Nuclear Polarization, has been used clinically in cancer patients. One way of ensuring a low bioburden of the hyperp......Signal enhancement by hyperpolarization is a way of overcoming the low sensitivity in magnetic resonance; MRI in particular. One of the most well-known methods, dissolution Dynamic Nuclear Polarization, has been used clinically in cancer patients. One way of ensuring a low bioburden...

  20. High-Frequency Dynamic Nuclear Polarization in the Nuclear Rotating Frame

    DEFF Research Database (Denmark)

    Farrar, C. T.; Hall, D. A.; Gerfen, G. J.

    2000-01-01

    A proton dynamic nuclear polarization (DNP) NMR signal enhancement (ϵ) close to thermal equilibrium, ϵ = 0.89, has been obtained at high field (B0 = 5 T, νepr = 139.5 GHz) using 15 mM trityl radical in a 40:60 water/glycerol frozen solution at 11 K. The electron-nuclear polarization transfer...... is performed in the nuclear rotating frame with microwave irradiation during a nuclear spin-lock pulse. The growth of the signal enhancement is governed by the rotating frame nuclear spin–lattice relaxation time (T1ρ), which is four orders of magnitude shorter than the nuclear spin–lattice relaxation time (T1n......). Due to the rapid polarization transfer in the nuclear rotating frame the experiment can be recycled at a rate of 1/T1ρ and is not limited by the much slower lab frame nuclear spin–lattice relaxation rate (1/T1n). The increased repetition rate allowed in the nuclear rotating frame provides an effective...

  1. Generating highly polarized nuclear spins in solution using dynamic nuclear polarization

    DEFF Research Database (Denmark)

    Wolber, J.; Ellner, F.; Fridlund, B.;

    2004-01-01

    and other low-γ nuclei. Subsequent to the DNP process, the solid sample is dissolved rapidly with a warm solvent to create a solution of molecules with highly polarized nuclear spins. Two main applications are proposed: high-resolution liquid state NMR with enhanced sensitivity, and the use......A method to generate strongly polarized nuclear spins in solution has been developed, using Dynamic Nuclear Polarization (DNP) at a temperature of 1.2K, and at a field of 3.354T, corresponding to an electron spin resonance frequency of 94GHz. Trityl radicals are used to directly polarize 13C...

  2. Dynamical Structure of Nuclear Excitation in Continuum

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chun-Lei; ZHANG Huan-Qiao; ZHANG Xi-Zhen

    2005-01-01

    @@ Dynamical structures of collective excitation in continuum are studied by calculating the isoscalar and isovector strength as well as transition density of nuclei near the drip-line such as 28O and 34Ca. It is found that for some excited states in continuum the proton and neutron transition density calculated from isoscalar and isovector excitation at some given energies may be different, which will affect the calculation of the polarization for nuclei with N ≠ Z.

  3. Dynamic Simulation and Optimization of Nuclear Hydrogen Production Systems

    Energy Technology Data Exchange (ETDEWEB)

    Paul I. Barton; Mujid S. Kaximi; Georgios Bollas; Patricio Ramirez Munoz

    2009-07-31

    This project is part of a research effort to design a hydrogen plant and its interface with a nuclear reactor. This project developed a dynamic modeling, simulation and optimization environment for nuclear hydrogen production systems. A hybrid discrete/continuous model captures both the continuous dynamics of the nuclear plant, the hydrogen plant, and their interface, along with discrete events such as major upsets. This hybrid model makes us of accurate thermodynamic sub-models for the description of phase and reaction equilibria in the thermochemical reactor. Use of the detailed thermodynamic models will allow researchers to examine the process in detail and have confidence in the accurary of the property package they use.

  4. Nuclear mass dependence of chaotic dynamics in Ginocchio model

    CERN Document Server

    Yoshinaga, N; Shigehara, T; Yoshinaga, Naotaka; Yoshida, Nobuaki; Shigehara, Takaomi

    1995-01-01

    The chaotic dynamics in nuclear collective motion is studied in the framework of a schematic shell model which has only monopole and quadrupole degrees of freedom. The model is shown to reproduce the experimentally observed global trend toward less chaotic motion in heavier nuclei. The relation between current approach and the earlier studies with bosonic models is discussed.

  5. Optically induced dynamic nuclear spin polarisation in diamond

    Science.gov (United States)

    Scheuer, Jochen; Schwartz, Ilai; Chen, Qiong; Schulze-Sünninghausen, David; Carl, Patrick; Höfer, Peter; Retzker, Alexander; Sumiya, Hitoshi; Isoya, Junichi; Luy, Burkhard; Plenio, Martin B.; Naydenov, Boris; Jelezko, Fedor

    2016-01-01

    The sensitivity of magnetic resonance imaging (MRI) depends strongly on nuclear spin polarisation and, motivated by this observation, dynamical nuclear spin polarisation has recently been applied to enhance MRI protocols (Kurhanewicz et al 2011 Neoplasia 13 81). Nuclear spins associated with the 13C carbon isotope (nuclear spin I = 1/2) in diamond possess uniquely long spin lattice relaxation times (Reynhardt and High 2011 Prog. Nucl. Magn. Reson. Spectrosc. 38 37). If they are present in diamond nanocrystals, especially when strongly polarised, they form a promising contrast agent for MRI. Current schemes for achieving nuclear polarisation, however, require cryogenic temperatures. Here we demonstrate an efficient scheme that realises optically induced 13C nuclear spin hyperpolarisation in diamond at room temperature and low ambient magnetic field. Optical pumping of a nitrogen-vacancy centre creates a continuously renewable electron spin polarisation which can be transferred to surrounding 13C nuclear spins. Importantly for future applications we also realise polarisation protocols that are robust against an unknown misalignment between magnetic field and crystal axis.

  6. NATO Advanced Study Institute on New Aspects of Nuclear Dynamics

    CERN Document Server

    Huberts, P

    1989-01-01

    The 1988 Summer School on New Aspects of Nuclear Dynamics took place in the style that by now has become a tradition: a series of lectures by well known scientists on modem topics of nuclear physics, where special emphasis is placed on the didactic aspects of the lectures. In the past few years, we have witnessed a rapid evolution of the field of nuclear physics towards novel directions of research. This development is accompanied by the construction of some of the largest experimental facilities ever built for nuclear research. The subjects covered by the Summer School focussed on two main issues currently under active investigation and which will be pursued with the new facilities: the transition from nucleonic to quark degrees of freedom in the decription of nuclear reactions, and the behavior of nuclear matter as one approaches extreme densities and temperatures. These topics in many respects go beyond traditional nuclear physics and the speakers therefore also included high energy physicists. From the re...

  7. Pasta nucleosynthesis: Molecular dynamics simulations of nuclear statistical equilibrium

    Science.gov (United States)

    Caplan, M. E.; Schneider, A. S.; Horowitz, C. J.; Berry, D. K.

    2015-06-01

    Background: Exotic nonspherical nuclear pasta shapes are expected in nuclear matter at just below saturation density because of competition between short-range nuclear attraction and long-range Coulomb repulsion. Purpose: We explore the impact nuclear pasta may have on nucleosynthesis during neutron star mergers when cold dense nuclear matter is ejected and decompressed. Methods: We use a hybrid CPU/GPU molecular dynamics (MD) code to perform decompression simulations of cold dense matter with 51 200 and 409 600 nucleons from 0.080 fm-3 down to 0.00125 fm-3 . Simulations are run for proton fractions YP= 0.05, 0.10, 0.20, 0.30, and 0.40 at temperatures T = 0.5, 0.75, and 1.0 MeV. The final composition of each simulation is obtained using a cluster algorithm and compared to a constant density run. Results: Size of nuclei in the final state of decompression runs are in good agreement with nuclear statistical equilibrium (NSE) models for temperatures of 1 MeV while constant density runs produce nuclei smaller than the ones obtained with NSE. Our MD simulations produces unphysical results with large rod-like nuclei in the final state of T =0.5 MeV runs. Conclusions: Our MD model is valid at higher densities than simple nuclear statistical equilibrium models and may help determine the initial temperatures and proton fractions of matter ejected in mergers.

  8. 32th Winter Workshop on Nuclear Dynamics

    CERN Document Server

    2016-01-01

    The 32nd edition of the Winter Workshop will be held 28 February - 5 March 2016, Hotel Resort Fort Royal Guadeloupe in Guadeloupe a French overseas territory, is an island group in the southern Caribbean Sea. As with previous years, the workshop will bring together scientists from all fields of nuclear physics for engaging and friendly exchanges of ideas. Much emphasis will be on the recent LHC, RHIC and SPS heavy ion results, but advances in the ongoing and future programs at FAIR, FRIB, EIC, JLab and NICA and will also be featured. The meeting will start with a welcome reception on the evening of Sunday, February 28. The workshop program will commence on Monday morning and run until Saturday. We recommend to arrive on Sunday and leave on Sunday. Talks will be as usual 25+5 minutes, there will be no parallel sessions. If you are interested in presenting your work, please fill out the registration form prior to the registration deadline. After the program committee has met we will confirm your talk via indivi...

  9. Nonlocalized cluster dynamics and nuclear molecular structure

    CERN Document Server

    Zhou, Bo; Horiuchi, Hisashi; Ren, Zhongzhou; Röpke, Gerd; Schuck, Peter; Tohsaki, Akihiro; Xu, Chang; Yamada, Taiichi

    2013-01-01

    A container picture is proposed for understanding cluster dynamics where the clusters make nonlocalized motion occupying the lowest orbit of the cluster mean-field potential characterized by the size parameter $``B"$ in the THSR (Tohsaki-Horiuchi-Schuck-R\\"{o}pke) wave function. The nonlocalized cluster aspects of the inversion-doublet bands in $^{20}$Ne which have been considered as a typical manifestation of localized clustering are discussed. So far unexplained puzzling features of the THSR wave function, namely that after angular-momentum projection for two cluster systems the prolate THSR wave function is almost 100$\\%$ equivalent to an oblate THSR wave function is clarified. It is shown that the true intrinsic two-cluster THSR configuration is nonetheless prolate. The proposal of the container picture is based on the fact that typical cluster systems, 2$\\alpha$, 3$\\alpha$, and $\\alpha$+$^{16}$O, are all well described by a single THSR wave function. It will be shown for the case of linear-chain states w...

  10. Adiabatic hyperspherical approach to large-scale nuclear dynamics

    CERN Document Server

    Suzuki, Yasuyuki

    2015-01-01

    We formulate a fully microscopic approach to large-scale nuclear dynamics using a hyperradius as a collective coordinate. An adiabatic potential is defined by taking account of all possible configurations at a fixed hyperradius, and its hyperradius dependence plays a key role in governing the global nuclear motion. In order to go to larger systems beyond few-body systems, we suggest basis functions of a microscopic multicluster model, propose a method for calculating matrix elements of an adiabatic Hamiltonian with use of Fourier transforms, and test its effectiveness.

  11. Pasta Nucleosynthesis: Molecular dynamics simulations of nuclear statistical equilibrium

    CERN Document Server

    Caplan, M E; Horowitz, C J; Berry, D K

    2014-01-01

    Background: Exotic non-spherical nuclear pasta shapes are expected in nuclear matter at just below saturation density because of competition between short range nuclear attraction and long range Coulomb repulsion. Purpose: We explore the impact of nuclear pasta on nucleosynthesis, during neutron star mergers, as cold dense nuclear matter is ejected and decompressed. Methods: We perform classical molecular dynamics simulations with 51200 and 409600 nucleons, that are run on GPUs. We expand our simulation region to decompress systems from an initial density of 0.080 fm^{-3} down to 0.00125 fm^{-3}. We study proton fractions of Y_P=0.05, 0.10, 0.20, 0.30, and 0.40 at T =0.5, 0.75, and 1.0 MeV. We calculate the composition of the resulting systems using a cluster algorithm. Results: We find final compositions that are in good agreement with nuclear statistical equilibrium models for temperatures of 0.75 and 1 MeV. However, for proton fractions greater than Y_P=0.2 at a temperature of T = 0.5 MeV, the MD simulatio...

  12. Parvovirus induced alterations in nuclear architecture and dynamics.

    Directory of Open Access Journals (Sweden)

    Teemu O Ihalainen

    Full Text Available The nucleus of interphase eukaryotic cell is a highly compartmentalized structure containing the three-dimensional network of chromatin and numerous proteinaceous subcompartments. DNA viruses induce profound changes in the intranuclear structures of their host cells. We are applying a combination of confocal imaging including photobleaching microscopy and computational methods to analyze the modifications of nuclear architecture and dynamics in parvovirus infected cells. Upon canine parvovirus infection, expansion of the viral replication compartment is accompanied by chromatin marginalization to the vicinity of the nuclear membrane. Dextran microinjection and fluorescence recovery after photobleaching (FRAP studies revealed the homogeneity of this compartment. Markedly, in spite of increase in viral DNA content of the nucleus, a significant increase in the protein mobility was observed in infected compared to non-infected cells. Moreover, analysis of the dynamics of photoactivable capsid protein demonstrated rapid intranuclear dynamics of viral capsids. Finally, quantitative FRAP and cellular modelling were used to determine the duration of viral genome replication. Altogether, our findings indicate that parvoviruses modify the nuclear structure and dynamics extensively. Intranuclear crowding of viral components leads to enlargement of the interchromosomal domain and to chromatin marginalization via depletion attraction. In conclusion, parvoviruses provide a useful model system for understanding the mechanisms of virus-induced intranuclear modifications.

  13. Time-dependent density-functional description of nuclear dynamics

    CERN Document Server

    Nakatsukasa, Takashi; Matsuo, Masayuki; Yabana, Kazuhiro

    2016-01-01

    We present the basic concepts and recent developments in the time-dependent density functional theory (TDDFT) for describing nuclear dynamics at low energy. The symmetry breaking is inherent in nuclear energy density functionals (EDFs), which provides a practical description of important correlations at the ground state. Properties of elementary modes of excitation are strongly influenced by the symmetry breaking and can be studied with TDDFT. In particular, a number of recent developments in the linear response calculation have demonstrated their usefulness in description of collective modes of excitation in nuclei. Unrestricted real-time calculations have also become available in recent years, with new developments for quantitative description of nuclear collision phenomena. There are, however, limitations in the real-time approach; for instance, it cannot describe the many-body quantum tunneling. Thus, we treat the quantum fluctuations associated with slow collective motions assuming that time evolution of...

  14. Molecular Dynamics of Nuclear Pasta in Neutron Stars

    Science.gov (United States)

    Briggs, Christian; da Silva Schneider, Andre

    2014-09-01

    During a core collapse supernova, a massive star undergoes rapid contraction followed by a massive explosion on the order of a hundred trillion trillion nuclear bombs in less than a second. While most matter is expelled at high speeds, what remains can form a neutron star. The bulk of a neutron star does not contain separate nuclei but is itself a single nucleus of radius ~10 km. In the crust of a neutron star, density is low enough that some matter exists as distinct nuclei arranged into crystalline lattice dominated by electromagnetic forces. Between the crust and core lies an interesting interface where matter is neither a single nucleus nor separate nuclei. It exists in a frustrated phase; competition between electromagnetic and strong nuclear forces causes exotic shapes to emerge, referred to as nuclear pasta. We use Molecular Dynamics (MD) to simulate nuclear pasta, with densities between nuclear saturation density and approximately one-tenth saturation density. Using MD particle trajectories, we compute the static structure factor S(q) and dynamical response function to describe both electron-pasta and neutrino-pasta scattering. We relate the structure and properties of nuclear pasta phases to features in S(q). Finally, one can integrate over S(q) to determine transport properties such as the electrical and thermal conductivity. This may help provide a better understanding of X-ray observations of neutron stars. During a core collapse supernova, a massive star undergoes rapid contraction followed by a massive explosion on the order of a hundred trillion trillion nuclear bombs in less than a second. While most matter is expelled at high speeds, what remains can form a neutron star. The bulk of a neutron star does not contain separate nuclei but is itself a single nucleus of radius ~10 km. In the crust of a neutron star, density is low enough that some matter exists as distinct nuclei arranged into crystalline lattice dominated by electromagnetic forces

  15. Pasta Elasticity: Molecular dynamics simulations of nuclear pasta deformations

    Science.gov (United States)

    Caplan, M. E.; Horowitz, C. J.; Berry, D. K.

    2015-04-01

    Nuclear pasta is expected in the inner crust of neutron stars at densities near the nuclear saturation density. In this work, the elastic properties of pasta are calculated from large scale molecular dynamics simulations by deforming the simulation volume. Our model uses a semi-classical two-nucleon potential that reproduces nuclear saturation. We report the shear modulus and breaking strain of a variety of pasta phases for different temperatures, densities, and proton fractions. The presence of pasta in neutron stars could have significant effects on crustal oscillations and could be inferred from observations of soft-gamma repeaters. Additionally, these elastic parameters will enable us to improve estimates of the maximum size and lifetime of ``mountains'' on the crust, which could efficiently radiate gravitational waves.

  16. A dynamical systems model for nuclear power plant risk

    Science.gov (United States)

    Hess, Stephen Michael

    The recent transition to an open access generation marketplace has forced nuclear plant operators to become much more cost conscious and focused on plant performance. Coincidentally, the regulatory perspective also is in a state of transition from a command and control framework to one that is risk-informed and performance-based. Due to these structural changes in the economics and regulatory system associated with commercial nuclear power plant operation, there is an increased need for plant management to explicitly manage nuclear safety risk. Application of probabilistic risk assessment techniques to model plant hardware has provided a significant contribution to understanding the potential initiating events and equipment failures that can lead to core damage accidents. Application of the lessons learned from these analyses has supported improved plant operation and safety over the previous decade. However, this analytical approach has not been nearly as successful in addressing the impact of plant processes and management effectiveness on the risks of plant operation. Thus, the research described in this dissertation presents a different approach to address this issue. Here we propose a dynamical model that describes the interaction of important plant processes among themselves and their overall impact on nuclear safety risk. We first provide a review of the techniques that are applied in a conventional probabilistic risk assessment of commercially operating nuclear power plants and summarize the typical results obtained. The limitations of the conventional approach and the status of research previously performed to address these limitations also are presented. Next, we present the case for the application of an alternative approach using dynamical systems theory. This includes a discussion of previous applications of dynamical models to study other important socio-economic issues. Next, we review the analytical techniques that are applicable to analysis of

  17. Dynamic response of nuclear fuel assembly excited by pressure pulsations

    Directory of Open Access Journals (Sweden)

    Zeman V.

    2012-12-01

    Full Text Available The paper deals with dynamic load calculation of the hexagonal type nuclear fuel assembly caused by spatial motion of the support plates in the reactor core. The support plate motion is excited by pressure pulsations generated by main circulation pumps in the coolant loops of the primary circuit of the nuclear power plant. Slightly different pumps revolutions generate the beat vibrations which causes an amplification of fuel assembly component dynamic deformations and fuel rods coating abrasion. The cyclic and central symmetry of the fuel assembly makes it possible the system decomposition into six identical revolved fuel rod segments which are linked with central tube and skeleton by several spacer grids in horizontal planes.The modal synthesis method with condensation of the fuel rod segments is used for calculation of the normal and friction forces transmitted between fuel rods and spacer grids cells.

  18. Tensor-optimized antisymmetrized molecular dynamics in nuclear physics

    CERN Document Server

    Myo, Takayuki; Ikeda, Kiyomi; Horiuchi, Hisashi; Suhara, Tadahiro

    2015-01-01

    We develop a new formalism to treat nuclear many-body systems using bare nucleon-nucleon interaction. It has become evident that the tensor interaction plays important role in nuclear many-body systems due to the role of the pion in strongly interacting system. We take the antisymmetrized molecular dynamics (AMD) as a basic framework and add a tensor correlation operator acting on the AMD wave function using the concept of the tensor-optimized shell model (TOSM). We demonstrate a systematical and straightforward formulation utilizing the Gaussian integration and differentiation method and the antisymmetrization technique to calculate all the matrix elements of the many-body Hamiltonian. We can include the three-body interaction naturally and calculate the matrix elements systematically in the progressive order of the tensor correlation operator. We call the new formalism "tensor-optimized antisymmetrized molecular dynamics".

  19. Dynamic Computer Model of a Stirling Space Nuclear Power System

    Science.gov (United States)

    2006-05-04

    Appendix E. 42 61 5. Heat Rejection System The liquid metal heat rejection loop feeds through the coolers of the Stirling converters to...load-following system , where load is based on the heat transferred and rejected by the Stirling heater and cooler to the working gas. A change in one...U.S.N.A. --- Trident Scholar project report; no. 345 (2006) DYNAMIC COMPUTER MODEL OF A STIRLING SPACE NUCLEAR POWER SYSTEM by

  20. Fractional calculus with applications for nuclear reactor dynamics

    CERN Document Server

    Ray, Santanu Saha

    2015-01-01

    Introduces Novel Applications for Solving Neutron Transport EquationsWhile deemed nonessential in the past, fractional calculus is now gaining momentum in the science and engineering community. Various disciplines have discovered that realistic models of physical phenomenon can be achieved with fractional calculus and are using them in numerous ways. Since fractional calculus represents a reactor more closely than classical integer order calculus, Fractional Calculus with Applications for Nuclear Reactor Dynamics focuses on the application of fractional calculus to describe the physical behavi

  1. Dynamic performance of concrete undercut anchors for Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Mahrenholtz, Christoph, E-mail: christoph@mahrenholtz.net; Eligehausen, Rolf

    2013-12-15

    Graphical abstract: - Highlights: • Behavior of undercut anchors under dynamic actions simulating earthquakes. • First high frequency load and crack cycling tests on installed concrete anchors ever. • Comprehensive review of anchor qualification for Nuclear Power Plants. - Abstract: Post-installed anchors are widely used for structural and nonstructural connections to concrete. In many countries, concrete anchors used for Nuclear Power Plants have to be qualified to ensure reliable behavior even under extreme conditions. The tests required for qualification of concrete anchors are carried out at quasi-static loading rates well below the rates to be expected for dynamic actions deriving from earthquakes, airplane impacts or explosions. To investigate potentially beneficial effects of high loading rates and cycling frequencies, performance tests on installed undercut anchors were conducted. After introductory notes on anchor technology and a comprehensive literature review, this paper discusses the qualification of anchors for Nuclear Power Plants and the testing carried out to quantify experimentally the effects of dynamic actions on the load–displacement behavior of undercut anchors.

  2. Dynamic nuclear polarization in a magnetic resonance force microscope experiment.

    Science.gov (United States)

    Issac, Corinne E; Gleave, Christine M; Nasr, Paméla T; Nguyen, Hoang L; Curley, Elizabeth A; Yoder, Jonilyn L; Moore, Eric W; Chen, Lei; Marohn, John A

    2016-04-01

    We report achieving enhanced nuclear magnetization in a magnetic resonance force microscope experiment at 0.6 tesla and 4.2 kelvin using the dynamic nuclear polarization (DNP) effect. In our experiments a microwire coplanar waveguide delivered radiowaves to excite nuclear spins and microwaves to excite electron spins in a 250 nm thick nitroxide-doped polystyrene sample. Both electron and proton spin resonance were observed as a change in the mechanical resonance frequency of a nearby cantilever having a micron-scale nickel tip. NMR signal, not observable from Curie-law magnetization at 0.6 T, became observable when microwave irradiation was applied to saturate the electron spins. The resulting NMR signal's size, buildup time, dependence on microwave power, and dependence on irradiation frequency was consistent with a transfer of magnetization from electron spins to nuclear spins. Due to the presence of an inhomogeneous magnetic field introduced by the cantilever's magnetic tip, the electron spins in the sample were saturated in a microwave-resonant slice 10's of nm thick. The spatial distribution of the nuclear polarization enhancement factor ε was mapped by varying the frequency of the applied radiowaves. The observed enhancement factor was zero for spins in the center of the resonant slice, was ε = +10 to +20 for spins proximal to the magnet, and was ε = -10 to -20 for spins distal to the magnet. We show that this bipolar nuclear magnetization profile is consistent with cross-effect DNP in a ∼10(5) T m(-1) magnetic field gradient. Potential challenges associated with generating and using DNP-enhanced nuclear magnetization in a nanometer-resolution magnetic resonance imaging experiment are elucidated and discussed.

  3. nuclear bound states in a dynamical model

    Science.gov (United States)

    Mareš, J.; Friedman, E.; Gal, A.

    2006-05-01

    A comprehensive data base of K-atom level shifts and widths is re-analyzed in order to study the density dependence of the K¯-nuclear optical potential. Significant departure from a tρ form is found only for ρ(r)/ρ ≲ 0.2 and extrapolation to nuclear-matter density ρ yields an attractive potential, about 170 MeV deep. Partial restoration of chiral symmetry compatible with pionic atoms and low-energy pion-nuclear data plays no role at the relevant low-density regime, but this effect is not ruled out at densities of order ρ and beyond. K¯-nuclear bound states are generated across the periodic table self consistently, using a relativistic mean-field model Lagrangian which couples the K¯ to the scalar and vector meson fields mediating the nuclear interactions. The reduced phase space available for K¯ absorption from these bound states is taken into account by adding an energy-dependent imaginary term which underlies the corresponding K¯-nuclear level widths, with a strength required by fits to the atomic data. Substantial polarization of the core nucleus is found for light nuclei, and the binding energies and widths calculated in this dynamical model differ appreciably from those calculated for a static nucleus. A wide range of binding energies is spanned by varying the K¯ couplings to the meson fields. Our calculations provide a lower limit of Γ=50±10 MeV on the width of nuclear bound states for K¯-binding energy in the range B˜100-200 MeV. Comments are made on the interpretation of the FINUDA experiment at DAΦNE which claimed evidence for deeply bound Kpp states in light nuclei.

  4. Spatiotemporal dynamics of the nuclear pore complex transport barrier resolved by high-speed atomic force microscopy

    Science.gov (United States)

    Sakiyama, Yusuke; Mazur, Adam; Kapinos, Larisa E.; Lim, Roderick Y. H.

    2016-08-01

    Nuclear pore complexes (NPCs) are biological nanomachines that mediate the bidirectional traffic of macromolecules between the cytoplasm and nucleus in eukaryotic cells. This process involves numerous intrinsically disordered, barrier-forming proteins known as phenylalanine-glycine nucleoporins (FG Nups) that are tethered inside each pore. The selective barrier mechanism has so far remained unresolved because the FG Nups have eluded direct structural analysis within NPCs. Here, high-speed atomic force microscopy is used to visualize the nanoscopic spatiotemporal dynamics of FG Nups inside Xenopus laevis oocyte NPCs at timescales of ∼100 ms. Our results show that the cytoplasmic orifice is circumscribed by highly flexible, dynamically fluctuating FG Nups that rapidly elongate and retract, consistent with the diffusive motion of tethered polypeptide chains. On this basis, intermingling FG Nups exhibit transient entanglements in the central channel, but do not cohere into a tightly crosslinked meshwork. Therefore, the basic functional form of the NPC barrier is comprised of highly dynamic FG Nups that manifest as a central plug or transporter when averaged in space and time.

  5. Fractional neutron point kinetics equations for nuclear reactor dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa-Paredes, Gilberto, E-mail: gepe@xanum.uam.mx [Area de Ingenieria en Recursos Energeticos, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, Mexico, D.F. 09340 (Mexico); Polo-Labarrios, Marco-A. [Area de Ingenieria en Recursos Energeticos, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, Mexico, D.F. 09340 (Mexico); Espinosa-Martinez, Erick-G. [Retorno Quebec 6, Col. Burgos de Cuernavaca 62580, Temixco, Mor. (Mexico); Valle-Gallegos, Edmundo del [Escuela Superior de Fisica y Matematicas, Instituto Politecnico Nacional, Av. Instituto Politecnico Nacional s/n, Col. San Pedro Zacatenco, Mexico, D.F. 07738 (Mexico)

    2011-02-15

    The fractional point-neutron kinetics model for the dynamic behavior in a nuclear reactor is derived and analyzed in this paper. The fractional model retains the main dynamic characteristics of the neutron motion in which the relaxation time associated with a rapid variation in the neutron flux contains a fractional order, acting as exponent of the relaxation time, to obtain the best representation of a nuclear reactor dynamics. The physical interpretation of the fractional order is related with non-Fickian effects from the neutron diffusion equation point of view. The numerical approximation to the solution of the fractional neutron point kinetics model, which can be represented as a multi-term high-order linear fractional differential equation, is calculated by reducing the problem to a system of ordinary and fractional differential equations. The numerical stability of the fractional scheme is investigated in this work. Results for neutron dynamic behavior for both positive and negative reactivity and for different values of fractional order are shown and compared with the classic neutron point kinetic equations. Additionally, a related review with the neutron point kinetics equations is presented, which encompasses papers written in English about this research topic (as well as some books and technical reports) published since 1940 up to 2010.

  6. Optical Bidirectional Associative Memories

    Science.gov (United States)

    Kosko, Bart; Guest, Clark

    1987-06-01

    Four optical implementations of bidirectional associative memories (BAMs) are presented. BAMs are heteroassociative content addressable memories (CAMs). A BAM stores the m binary associations (A1, B1), ..., (Am, Bm) , where A is a point in the Boolean n-cube and B is a point in the Boolean p-cube. A is a neural network of n bivalent or continuous neurons ai; B is a network of p bivalent or continuous neurons bi. The fixed synaptic connections between the A and B networks are represented by some n-by-p real matrix M. Bidirectionality, forward and backward information flow, in neural nets produces two-way associative search for the nearest stored pair (Ai, Bi) to an input key. Every matrix is a bidirectionally stable hetero-associative CAM for boh bivalent and continuous networks. This generalizes the well-known unidirectional stability for autoassociative networks with square symmetric M. When the BAM neurons are activated, the network quickly evolves to a stable state of two-pattern reverberation, or pseudo-adaptive resonance. The stable reverberation corresponds to a system energy local minimum. Heteroassociative pairs (Ai, Bi) are encoded in a BAM M by summing bipolar correlation matrices, M = X1T Y1 + ... + XmT Ym , where Xi (Yi) is the bipolar version of Ai (Bi), with -1s replacing Os. the BAM storage capacity for reliable recall is roughly m reflection hologram, and a transmission hologram.

  7. ABOUT HYBRID BIDIRECTIONAL ASSOCIATIVE MEMORY NEURAL NETWORKS WITH DISCRETE DELAYS

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this paper, hybrid bidirectional associative memory neural networks with discrete delays is considered. By ingeniously importing real parameters di > 0(i = 1,2,···,n) which can be adjusted, we establish some new sufficient conditions for the dynamical characteristics of hybrid bidirectional associative memory neural networks with discrete delays by the method of variation of parameters and some analysis techniques. Our results generalize and improve the related results in [10,11]. Our work is significant...

  8. Nuclear Hybrid Energy System Modeling: RELAP5 Dynamic Coupling Capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Piyush Sabharwall; Nolan Anderson; Haihua Zhao; Shannon Bragg-Sitton; George Mesina

    2012-09-01

    The nuclear hybrid energy systems (NHES) research team is currently developing a dynamic simulation of an integrated hybrid energy system. A detailed simulation of proposed NHES architectures will allow initial computational demonstration of a tightly coupled NHES to identify key reactor subsystem requirements, identify candidate reactor technologies for a hybrid system, and identify key challenges to operation of the coupled system. This work will provide a baseline for later coupling of design-specific reactor models through industry collaboration. The modeling capability addressed in this report focuses on the reactor subsystem simulation.

  9. Bidirectional reflectance of zinc oxide

    Science.gov (United States)

    Scott, R.

    1973-01-01

    This investigation was undertaken to determine original and useful information about the bidirection reflectance of zinc oxide. The bidirectional reflectance will be studied for the spectra between .25-2.5 microns and the hemisphere above the specimen. The following factors will be considered: (1) surface conditions; (2) specimen preparation; (3) specimen substrate, (4) polarization; (5) depolarization; (6) wavelength; and (7) angles of incident and reflection. The bidirectional reflectance will be checked by experimentally determined angular hemispherical measurements or hemispherical measurements will be used to obtain absolute bidirectional reflectance.

  10. Isospin dynamics on neck fragmentation in isotopic nuclear reactions

    CERN Document Server

    Feng, Zhao-Qing

    2016-01-01

    The neck dynamics in Fermi-energy heavy-ion collisions, to probe the nuclear symmetry energy in the domain of sub-saturation densities, is investigated within an isospin dependent transport model. The single and double ratios of neutron/proton from free nucleons and light clusters (complex particles) in the isotopic reactions are analyzed systematically. Isospin effects of particles produced from the neck fragmentations are explored, which are constrained within the midrapidities ($|y/y_{proj}|<$0.3) and azimuthal angles (70$^{o}\\sim$110$^{o}$, 250$^{o}\\sim$290$^{o}$) in semiperipheral nuclear collisions. It is found that the ratios of the energetic isospin particles strongly depend on the stiffness of nuclear symmetry energy and the effects increase with softening the symmetry energy, which would be a nice probe for extracting the symmetry energy below the normal density in experimentally. A flat structure appears at the tail spectra from the double ratio distributions. The neutron to proton ratio of ligh...

  11. Inhomogeneous dynamic nuclear polarization and suppression of electron polarization decay in a quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Na [Department of Optical Science and Engineering, Fudan University, Shanghai 200433 (China); School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072 (China); Ding, Wenkui; Shi, Anqi [School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072 (China); Zhang, Wenxian, E-mail: wxzhang@whu.edu.cn [School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072 (China)

    2016-08-12

    We investigate the dynamic nuclear polarization in a quantum dot. Due to the suppression of direct dipolar and indirect electron-mediated nuclear spin interactions by frequently injected electron spins, our analytical results under independent spin approximation agree well with quantum numerical simulations for a small number of nuclear spins. We find that the acquired nuclear polarization is highly inhomogeneous, proportional to the square of the local electron-nuclear hyperfine interaction constant. Starting from the inhomogeneously polarized nuclear spins, we further show that the electron polarization decay time can be extended 100 times even at a relatively low nuclear polarization. - Highlights: • Nuclear spin polarization is highly inhomogeneous after a dynamic nuclear polarization (DNP) process. • The DNP process is well described by an analytical model based on the independent spin approximation. • The highly inhomogeneous nuclear polarization significantly prolongs the electron spin coherence time.

  12. Morphological bidirectional associative memories.

    Science.gov (United States)

    Ritter, G X.; Diaz-de-Leon, J L.; Sussner, P

    1999-07-01

    The theory of artificial neural networks has been successfully applied to a wide variety of pattern recognition problems. In this theory, the first step in computing the next state of a neuron or in performing the next layer neural network computation involves the linear operation of multiplying neural values by their synaptic strengths and adding the results. Thresholding usually follows the linear operation in order to provide for nonlinearity of the network. In this paper we discuss a novel class of artificial neural networks, called morphological neural networks, in which the operations of multiplication and addition are replaced by addition and maximum (or minimum), respectively. By taking the maximum (or minimum) of sums instead of the sum of products, morphological network computation is nonlinear before thresholding. As a consequence, the properties of morphological neural networks are drastically different from those of traditional neural network models. The main emphasis of the research presented here is on morphological bidirectional associative memories (MBAMs). In particular, we establish a mathematical theory for MBAMs and provide conditions that guarantee perfect bidirectional recall for corrupted patterns. Some examples that illustrate performance differences between the morphological model and the traditional semilinear model are also given.

  13. A Statistical Theory of Bidirectionality

    Science.gov (United States)

    DeLoach, Richard; Ulbrich, Norbert

    2013-01-01

    Original concepts related to the quantification and assessment of bidirectionality in strain-gage balances were introduced by Ulbrich in 2012. These concepts are extended here in three ways: 1) the metric originally proposed by Ulbrich is normalized, 2) a categorical variable is introduced in the regression analysis to account for load polarity, and 3) the uncertainty in both normalized and non-normalized bidirectionality metrics is quantified. These extensions are applied to four representative balances to assess the bidirectionality characteristics of each. The paper is tutorial in nature, featuring reviews of certain elements of regression and formal inference. Principal findings are that bidirectionality appears to be a common characteristic of most balance outputs and that unless it is taken into account, it is likely to consume the entire error budget of a typical balance calibration experiment. Data volume and correlation among calibration loads are shown to have a significant impact on the precision with which bidirectionality metrics can be assessed.

  14. A general model for bidirectional associative memories.

    Science.gov (United States)

    Shi, H; Zhao, Y; Zhuang, X

    1998-01-01

    This paper proposes a general model for bidirectional associative memories that associate patterns between the X-space and the Y-space. The general model does not require the usual assumption that the interconnection weight from a neuron in the X-space to a neuron in the Y-space is the same as the one from the Y-space to the X-space. We start by defining a supporting function to measure how well a state supports another state in a general bidirectional associative memory (GBAM). We then use the supporting function to formulate the associative recalling process as a dynamic system, explore its stability and asymptotic stability conditions, and develop an algorithm for learning the asymptotic stability conditions using the Rosenblatt perceptron rule. The effectiveness of the proposed model for recognition of noisy patterns and the performance of the model in terms of storage capacity, attraction, and spurious memories are demonstrated by some outstanding experimental results.

  15. Bidirectional Modulation of Numerical Magnitude.

    Science.gov (United States)

    Arshad, Qadeer; Nigmatullina, Yuliya; Nigmatullin, Ramil; Asavarut, Paladd; Goga, Usman; Khan, Sarah; Sander, Kaija; Siddiqui, Shuaib; Roberts, R E; Cohen Kadosh, Roi; Bronstein, Adolfo M; Malhotra, Paresh A

    2016-05-01

    Numerical cognition is critical for modern life; however, the precise neural mechanisms underpinning numerical magnitude allocation in humans remain obscure. Based upon previous reports demonstrating the close behavioral and neuro-anatomical relationship between number allocation and spatial attention, we hypothesized that these systems would be subject to similar control mechanisms, namely dynamic interhemispheric competition. We employed a physiological paradigm, combining visual and vestibular stimulation, to induce interhemispheric conflict and subsequent unihemispheric inhibition, as confirmed by transcranial direct current stimulation (tDCS). This allowed us to demonstrate the first systematic bidirectional modulation of numerical magnitude toward either higher or lower numbers, independently of either eye movements or spatial attention mediated biases. We incorporated both our findings and those from the most widely accepted theoretical framework for numerical cognition to present a novel unifying computational model that describes how numerical magnitude allocation is subject to dynamic interhemispheric competition. That is, numerical allocation is continually updated in a contextual manner based upon relative magnitude, with the right hemisphere responsible for smaller magnitudes and the left hemisphere for larger magnitudes.

  16. Membrane proteins structure and dynamics by nuclear magnetic resonance.

    Science.gov (United States)

    Maltsev, Sergey; Lorigan, Gary A

    2011-10-01

    Membrane proteins represent a challenging class of biological systems to study. They are extremely difficult to crystallize and in most cases they retain their structure and functions only in membrane environments. Therefore, commonly used diffraction methods fail to give detailed molecular structure and other approaches have to be utilized to obtain biologically relevant information. Nuclear magnetic resonance (NMR) spectroscopy, however, can provide powerful structural and dynamical constraints on these complicated systems. Solution- and solid-state NMR are powerful methods for investigating membrane proteins studies. In this work, we briefly review both solution and solid-state NMR techniques for membrane protein studies and illustrate the applications of these methods to elucidate proteins structure, conformation, topology, dynamics, and function. Recent advances in electronics, biological sample preparation, and spectral processing provided opportunities for complex biological systems, such as membrane proteins inside lipid vesicles, to be studied faster and with outstanding quality. New analysis methods therefore have emerged, that benefit from the combination of sample preparation and corresponding specific high-end NMR techniques, which give access to more structural and dynamic information.

  17. LISA double black holes: Dynamics in gaseous nuclear discs

    CERN Document Server

    Dotti, M; Haardt, F

    2006-01-01

    We study the inspiral of double black holes, with masses in the LISA window of detectability, orbiting inside a massive circum-nuclear disc. Using high-resolution SPH simulations, we follow the black hole dynamics in the early phase when gas-dynamical friction acts on the black holes individually, and continue our simulation until they form a close binary. We find that in the early sinking the black holes loose memory of their initial orbital eccentricity if they co-rotate with the gaseous disc. As a consequence the massive black holes bind forming a binary with a low eccentricity, consistent with zero within our numerical resolution limit. The cause of circularization resides in the rotation present in the gaseous background where dynamical friction operates. Circularization may hinder gravitational waves from taking over and leading the binary to coalescence. In the case of counter-rotating orbits the initial eccentricity (if present) does not decreases, and the black holes may bind forming an eccentric bin...

  18. Towards an efficient multiphysics model for nuclear reactor dynamics

    Directory of Open Access Journals (Sweden)

    Obaidurrahman K.

    2015-01-01

    Full Text Available Availability of fast computer resources nowadays has facilitated more in-depth modeling of complex engineering systems which involve strong multiphysics interactions. This multiphysics modeling is an important necessity in nuclear reactor safety studies where efforts are being made worldwide to combine the knowledge from all associated disciplines at one place to accomplish the most realistic simulation of involved phenomenon. On these lines coupled modeling of nuclear reactor neutron kinetics, fuel heat transfer and coolant transport is a regular practice nowadays for transient analysis of reactor core. However optimization between modeling accuracy and computational economy has always been a challenging task to ensure the adequate degree of reliability in such extensive numerical exercises. Complex reactor core modeling involves estimation of evolving 3-D core thermal state, which in turn demands an expensive multichannel based detailed core thermal hydraulics model. A novel approach of power weighted coupling between core neutronics and thermal hydraulics presented in this work aims to reduce the bulk of core thermal calculations in core dynamics modeling to a significant extent without compromising accuracy of computation. Coupled core model has been validated against a series of international benchmarks. Accuracy and computational efficiency of the proposed multiphysics model has been demonstrated by analyzing a reactivity initiated transient.

  19. Dynamic nuclear-polarization studies of paramagnetic species in solution

    Energy Technology Data Exchange (ETDEWEB)

    Glad, W.E.

    1982-07-01

    Dynamic Nuclear Polarization (DNP) was used to measure the electron spin lattice relaxation times, T/sub 1/, of transition metal ions in aqueous solution. Saturation which is induced in the electron spin system is transferred to the solvent proton spins by dipole-dipole interactions. The change in the polarization of the proton spins is much larger than it is in the electron spins. The change in proton polarization is easily measured by proton Nuclear Magnetic Resonance (NMR). In one experimental arrangement the sample solution was continuously flowed through a microwave cavity to the NMR coil. The NMR was observed with a continuous wave NMR spectrometer. In a second arrangement the whole sample tube was moved from within the microwave cavity to the NMR coil in less than 40 ms by a blast of compressed air. The NMR was then observed with a pulse-Fourier-transform spectrometer. With the second arrangement a mean-square microwave magnetic field at the sample of more than 10 G/sup 2/ is obtainable with 14 W of microwave power. Measurements of DNP at 9 GHz were made on aqueous solutions of VO/sup 2 +/, Mn/sup 2 +/, Cr(CN)/sub 6//sup 3 -/, Cu/sup 2 +/ and Cu(ethylenediamine)/sub 2/(H/sub 2/0)/sub 2//sup 2 +/ ions from 3 to 60/sup 0/C. It was also possible to observe DNP on resolved proton resonances from mixed water-acetonitrile solutions of VO/sup 2 +/ and Cr(CN)/sub 6//sup 3 -/ ions.

  20. The dynamic nature of the nuclear envelope: lessons from closed mitosis.

    Science.gov (United States)

    Arnone, James T; Walters, Alison D; Cohen-Fix, Orna

    2013-01-01

    In eukaryotes, chromosomes are encased by a dynamic nuclear envelope. In contrast to metazoans, where the nuclear envelope disassembles during mitosis, many fungi including budding yeast undergo "closed mitosis," where the nuclear envelope remains intact throughout the cell cycle. Consequently, during closed mitosis the nuclear envelope must expand to accommodate chromosome segregation to the two daughter cells. A recent study by Witkin et al. in budding yeast showed that if progression through mitosis is delayed, for example due to checkpoint activation, the nuclear envelope continues to expand despite the block to chromosome segregation. Moreover, this expansion occurs at a specific region of the nuclear envelope- adjacent to the nucleolus- forming an extension referred to as a "flare." These observations raise questions regarding the regulation of nuclear envelope expansion both in budding yeast and in higher eukaryotes, the mechanisms confining mitotic nuclear envelope expansion to a particular region and the possible consequences of failing to regulate nuclear envelope expansion during the cell cycle.

  1. Nuclear magnetic resonance studies of macroscopic morphology and dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Barrall, Geoffrey Alden [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

    1995-09-01

    Nuclear magnetic resonance techniques are traditionally used to study molecular level structure and dynamics with a noted exception in medically applied NMR imaging (MRI). In this work, new experimental methods and theory are presented relevant to the study of macroscopic morphology and dynamics using NMR field gradient techniques and solid state two-dimensional exchange NMR. The goal in this work is not to take some particular system and study it in great detail, rather it is to show the utility of a number of new and novel techniques using ideal systems primarily as a proof of principle. By taking advantage of the analogy between NMR imaging and diffraction, one may simplify the experiments necessary for characterizing the statistical properties of the sample morphology. For a sample composed of many small features, e.g. a porous medium, the NMR diffraction techniques take advantage of both the narrow spatial range and spatial isotropy of the sample`s density autocorrelation function to obtain high resolution structural information in considerably less time than that required by conventional NMR imaging approaches. The time savings of the technique indicates that NMR diffraction is capable of finer spatial resolution than conventional NMR imaging techniques. Radio frequency NMR imaging with a coaxial resonator represents the first use of cylindrically symmetric field gradients in imaging. The apparatus as built has achieved resolution at the micron level for water samples, and has the potential to be very useful in the imaging of circularly symmetric systems. The study of displacement probability densities in flow through a random porous medium has revealed the presence of features related to the interconnectedness of the void volumes. The pulsed gradient techniques used have proven successful at measuring flow properties for time and length scales considerably shorter than those studied by more conventional techniques.

  2. Dynamical nuclear polarization using multi-colour control of color centers in diamond

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Pengcheng [Huazhong University of Science and Technology, School of Physics, Wuhan (China); Huazhong University of Science and Technology, Center for Quantum Optical Science, Wuhan (China); Plenio, Martin B. [Universitaet Ulm, Institut fuer Theoretische Physik, Ulm (Germany); Universitaet Ulm, Center for Integrated Quantum Science and Technology, Ulm (Germany); Cai, Jianming [Huazhong University of Science and Technology, School of Physics, Wuhan (China); Huazhong University of Science and Technology, Center for Quantum Optical Science, Wuhan (China); Universitaet Ulm, Institut fuer Theoretische Physik, Ulm (Germany); Universitaet Ulm, Center for Integrated Quantum Science and Technology, Ulm (Germany)

    2016-12-15

    Dynamical nuclear polarization (DNP) transfers the polarization of electron spins at cryogenic temperatures to achieve strong nuclear polarization for applications in nuclear magnetic resonance. Recently introduced approaches employ optical pumping of nitrogen-vacancy (NV) centers in diamond to achieve DNP even at ambient temperatures. In such schemes microwave radiation is used to establish a Hartmann-Hahn condition between the NV electron spin and proximal nuclear spins to facilitate polarization transfer. For a single monochromatic microwave driving field, the Hartmann-Hahn condition cannot be satisfied for an ensemble of NV centers due to inhomogeneous broadening and reduces significantly the overall efficiency of dynamical nuclear polarization using an ensemble of NV centers. Here, we adopt generalized Hartmann-Hahn type dynamical nuclear polarization schemes by applying microwave driving fields with (multiple) time-modulated frequencies. We show that it is possible to enhance the effective coupling between an ensemble of NV center spins with inhomogeneous broadening and nuclear spins, thereby improving significantly the overall efficiency of dynamical nuclear polarization. This approach can also be used to achieve dynamical nuclear polarization of an ensemble of nuclei with a distribution of Larmor frequencies, which would be helpful in magnetic resonance spectroscopy using a single NV spin sensor. (orig.)

  3. Dynamic range of GSK3α not GSK3β is essential for bidirectional synaptic plasticity at hippocampal CA3-CA1 synapses

    Science.gov (United States)

    Shahab, Lion; Plattner, Florian; Irvine, Elaine E; Cummings, Damian M; Edwards, Frances A

    2014-01-01

    Glycogen synthase kinase-3 (GSK3), particularly the isoform GSK3β, has been implicated in a wide range of physiological systems and neurological disorders including Alzheimer's Disease. However, the functional importance of GSK3α has been largely untested. The multifunctionality of GSK3 limits its potential as a drug target because of inevitable side effects. Due to its greater expression in the CNS, GSK3β rather than GSK3α has also been assumed to be of primary importance in synaptic plasticity. Here, we investigate bidirectional long-term synaptic plasticity in knockin mice with a point mutation in GSK3α or GSK3β that prevents their inhibitory regulation. We report that only the mutation in GSK3α affects long-term potentiation (LTP) and depression (LTD). This stresses the importance of investigating isoform specificity for GSK3 in all systems and suggests that GSK3α should be investigated as a drug target in cognitive disorders including Alzheimer's Disease. © 2014 The Authors. Hippocampus Published by Wiley Periodicals, Inc. PMID:25208523

  4. VISION -- A Dynamic Model of the Nuclear Fuel Cycle

    Energy Technology Data Exchange (ETDEWEB)

    J. J. Jacobson; A. M. Yacout; S. J. Piet; D. E. Shropshire; G. E. Matthern

    2006-02-01

    The Advanced Fuel Cycle Initiative’s (AFCI) fundamental objective is to provide technology options that – if implemented – would enable long-term growth of nuclear power while improving sustainability and energy security. The AFCI organization structure consists of four areas; Systems Analysis, Fuels, Separations and Transmutations. The Systems Analysis Working Group is tasked with bridging the program technical areas and providing the models, tools, and analyses required to assess the feasibility of design and deploy¬ment options and inform key decision makers. An integral part of the Systems Analysis tool set is the development of a system level model that can be used to examine the implications of the different mixes of reactors, implications of fuel reprocessing, impact of deployment technologies, as well as potential “exit” or “off ramp” approaches to phase out technologies, waste management issues and long-term repository needs. The Verifiable Fuel Cycle Simulation Model (VISION) is a computer-based simulation model that allows performing dynamic simulations of fuel cycles to quantify infrastructure requirements and identify key trade-offs between alternatives. VISION is intended to serve as a broad systems analysis and study tool applicable to work conducted as part of the AFCI (including costs estimates) and Generation IV reactor development studies.

  5. Dissolution Dynamic Nuclear Polarization capability study with fluid path

    Science.gov (United States)

    Malinowski, Ronja M.; Lipsø, Kasper W.; Lerche, Mathilde H.; Ardenkjær-Larsen, Jan H.

    2016-11-01

    Signal enhancement by hyperpolarization is a way of overcoming the low sensitivity in magnetic resonance; MRI in particular. One of the most well-known methods, dissolution Dynamic Nuclear Polarization, has been used clinically in cancer patients. One way of ensuring a low bioburden of the hyperpolarized product is by use of a closed fluid path that constitutes a barrier to contamination. The fluid path can be filled with the pharmaceuticals, i.e. imaging agent and solvents, in a clean room, and then stored or immediately used at the polarizer. In this study, we present a method of filling the fluid path that allows it to be reused. The filling method has been investigated in terms of reproducibility at two extrema, high dose for patient use and low dose for rodent studies, using [1-13C]pyruvate as example. We demonstrate that the filling method allows high reproducibility of six quality control parameters with standard deviations 3-10 times smaller than the acceptance criteria intervals in clinical studies.

  6. Nuclear coups: dynamics of black holes in galaxy mergers

    CERN Document Server

    Van Wassenhove, Sandor; Volonteri, Marta; Dotti, Massimo; Bellovary, Jillian M; Mayer, Lucio; Governato, Fabio

    2013-01-01

    We study the dynamical evolution of supermassive black holes (BHs) in merging galaxies on scales of hundreds of kpc to 10 pc, to highlight and identify the physical processes that aid or hinder the orbital decay of BHs down to pc scale. We present hydrodynamical simulations of unequal-mass galaxy mergers ($G_1$ and $G_2$ are the larger and smaller galaxies, respectively), with a variety of orbital configurations, that bridge the gap between large-scale, low-resolution merger simulations and the small-scale, high-resolution simulations of BH-binary evolution. Our simulations resolve $<20$-pc scales in order to accurately track the motion of the nuclei and provide a realistic environment for the evolution of the BHs. We find that, during the late stages of the merger, tidal shocks inject energy in the nuclei ($N_1$ and $N_2$), causing one or both nuclei to be disrupted and leaving their BH 'naked', without any bound gas or stars. In many cases, the nucleus that is ultimately disrupted is $N_1$ ('nuclear coup...

  7. A time-correlation function approach to nuclear dynamical effects in X-ray spectroscopy

    CERN Document Server

    Karsten, Sven; Aziz, Saadullah G; Ivanov, Sergei D; Kühn, Oliver

    2016-01-01

    Modern X-ray spectroscopy has proven itself as a robust tool for probing the electronic structure of atoms in complex environments. Despite working on energy scales that are much larger than those corresponding to nuclear motions, taking nuclear dynamics and the associated nuclear correlations into account may be of importance for X-ray spectroscopy. Recently, we have developed an efficient protocol to account for nuclear dynamics in X-ray absorption and resonant inelastic X-ray scattering spectra [Karsten \\textit{et al.} arXiv:1608.03436], based on ground state molecular dynamics accompanied with state-of-the-art calculations of electronic excitation energies and transition dipoles. Here, we present an alternative derivation of the formalism and elaborate on the developed simulation protocol on the examples of gas phase and bulk water. The specific spectroscopic features stemming from the nuclear motions are analyzed and traced down to the dynamics of electronic energy gaps and transition dipole correlation ...

  8. Information flow and protein dynamics: the interplay between nuclear magnetic resonance spectroscopy and molecular dynamics simulations

    Science.gov (United States)

    Pastor, Nina; Amero, Carlos

    2015-01-01

    Proteins participate in information pathways in cells, both as links in the chain of signals, and as the ultimate effectors. Upon ligand binding, proteins undergo conformation and motion changes, which can be sensed by the following link in the chain of information. Nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations represent powerful tools for examining the time-dependent function of biological molecules. The recent advances in NMR and the availability of faster computers have opened the door to more detailed analyses of structure, dynamics, and interactions. Here we briefly describe the recent applications that allow NMR spectroscopy and MD simulations to offer unique insight into the basic motions that underlie information transfer within and between cells. PMID:25999971

  9. Information Flow and Protein Dynamics: the Interplay Between Nuclear Magnetic Resonance Spectroscopy and Molecular Dynamics Simulations

    Directory of Open Access Journals (Sweden)

    Nina ePastor

    2015-05-01

    Full Text Available Proteins participate in information pathways in cells, both as links in the chain of signals, and as the ultimate effectors. Upon ligand binding, proteins undergo conformation and motion changes, which can be sensed by the following link in the chain of information. Nuclear magnetic resonance (NMR spectroscopy and molecular dynamics (MD simulations represent powerful tools for examining the time-dependent function of biological molecules. The recent advances in NMR and the availability of faster computers have opened the door to more detailed analyses of structure, dynamics and interactions. Here we briefly describe the recent applications that allow NMR spectroscopy and MD simulations to offer unique insight into the basic motions that underlie information transfer within and between cells.

  10. Breakdown Phenomenon Study in the Bidirectional Pedestrian Flow

    NARCIS (Netherlands)

    Yang, X.; Daamen, W.; Hoogendoorn, S.P.; Chen, Y.; Dong, H.

    2014-01-01

    Pedestrian dynamics has been being a popular research area. In this paper, breakdown probability in the bidirectional flow that includes pedestrians with heterogeneities is investigated. Reaction time appears to have the most pronounced breakdown proba- bility, followed by desired velocity and then

  11. Dynamic nuclear polarization polarizer for sterile use intent.

    Science.gov (United States)

    Ardenkjaer-Larsen, Jan H; Leach, Andrew M; Clarke, Neil; Urbahn, John; Anderson, Denise; Skloss, Timothy W

    2011-10-01

    A novel polarizer based on the dissolution-dynamic nuclear polarization (DNP) method has been designed, built and tested. The polarizer differs from those previously described by being designed with sterile use intent and being compatible with clinical use. The main features are: (1) an integral, disposable fluid path containing all pharmaceuticals constituting a sterile barrier, (2) a closed-cycle cryogenic system designed to eliminate consumption of liquid cryogens and (3) multi-sample polarization to increase throughput. The fluid path consists of a vial with the agent to be polarized, a pair of concentric inlet and outlet tubes connected to a syringe with dissolution medium and a receiver, respectively. The fluid path can operate at up to 400 K and 2.0 MPa and generates volumes as high as 100 mL. An inline filter removes the amount of electron paramagnetic agent in the final product by more than 100-fold in the case of [1-(13)C]pyruvate. The system uses a sorption pump in conjunction with a conventional cryocooler. The system operates through cycles of pumping to low temperature and regeneration of the sorption pump. The magnet accommodates four samples at the same time. A temperature of less than 1 K was achieved for 68 h (no sample heat loads) with a liquid helium volume of 2.4 L. The regeneration of the liquid helium could be achieved in less than 10 h, and the transition to cold (helium bath by introducing the sample over 15 min. The heat load imposed on the helium bath during dissolution was less than 70 J. The measured liquid state polarization was 18 ± 2%.

  12. Quantum wavepacket ab initio molecular dynamics: an approach for computing dynamically averaged vibrational spectra including critical nuclear quantum effects.

    Science.gov (United States)

    Sumner, Isaiah; Iyengar, Srinivasan S

    2007-10-18

    We have introduced a computational methodology to study vibrational spectroscopy in clusters inclusive of critical nuclear quantum effects. This approach is based on the recently developed quantum wavepacket ab initio molecular dynamics method that combines quantum wavepacket dynamics with ab initio molecular dynamics. The computational efficiency of the dynamical procedure is drastically improved (by several orders of magnitude) through the utilization of wavelet-based techniques combined with the previously introduced time-dependent deterministic sampling procedure measure to achieve stable, picosecond length, quantum-classical dynamics of electrons and nuclei in clusters. The dynamical information is employed to construct a novel cumulative flux/velocity correlation function, where the wavepacket flux from the quantized particle is combined with classical nuclear velocities to obtain the vibrational density of states. The approach is demonstrated by computing the vibrational density of states of [Cl-H-Cl]-, inclusive of critical quantum nuclear effects, and our results are in good agreement with experiment. A general hierarchical procedure is also provided, based on electronic structure harmonic frequencies, classical ab initio molecular dynamics, computation of nuclear quantum-mechanical eigenstates, and employing quantum wavepacket ab initio dynamics to understand vibrational spectroscopy in hydrogen-bonded clusters that display large degrees of anharmonicities.

  13. Dynamical Screening Effect on $\\alpha$-$\\alpha$ Resonant Scattering and Thermal Nuclear Scattering Rate

    CERN Document Server

    Yao, Xiaojun; Müller, Berndt

    2016-01-01

    We study the dynamical screening effect in the QED plasma on the $\\alpha$-$\\alpha$ scattering at the $^8$Be resonance. Dynamical screening leads to an imaginary part of the potential which results in a thermal width for the resonance and dominates over the previously considered static screening effect. As a result, both the resonance energy and width increase with the plasma temperature. Furthermore, dynamical screening can have a huge impact on the $\\alpha$-$\\alpha$ thermal nuclear scattering rate. For example, when the temperature is around $10$ keV, the rate is suppressed by a factor of about $900$. We expect similar thermal suppressions of nuclear reaction rates to occur in nuclear reactions dominated by an above threshold resonance with a thermal energy. Dynamical screening effects on nuclear reactions can be relevant to cosmology and astrophysics.

  14. Cleave to Leave : Structural Insights into the Dynamic Organization of the Nuclear Pore Complex

    NARCIS (Netherlands)

    Dokudovskaya, Svetlana; Veenhoff, Liesbeth M.; Rout, Michael P.

    2002-01-01

    A detailed understanding of the fine structure of the nuclear pore complex has remained elusive. Now, studies on a small protein domain have shed light on the dynamic organization of this massive assembly.

  15. Cluster formation restricts dynamic nuclear polarization of xenon in solid mixtures

    DEFF Research Database (Denmark)

    Kuzma, N. N.; Pourfathi, M.; Kara, H.

    2012-01-01

    During dynamic nuclear polarization (DNP) at 1.5 K and 5 T, Xe-129 nuclear magnetic resonance (NMR) spectra of a homogeneous xenon/1-propanol/trityl-radical solid mixture exhibit a single peak, broadened by H-1 neighbors. A second peak appears upon annealing for several hours at 125 K. Its...

  16. Electron paramagnetic resonance and dynamic nuclear polarization of char suspensions: surface science and oximetry

    DEFF Research Database (Denmark)

    Clarkson, R B; Odintsov, B M; Ceroke, P J

    1998-01-01

    ; they can be calibrated and used for oximetry. Biological stability and low toxicity make chars good sensors for in vivo measurements. Scalar and dipolar interactions of water protons at the surfaces of chars may be utilized to produce dynamic nuclear polarization (DNP) of the nuclear spin population...

  17. Microtubules as key coordinators of nuclear envelope and endoplasmic reticulum dynamics during mitosis.

    Science.gov (United States)

    Schlaitz, Anne-Lore

    2014-07-01

    During mitosis, cells comprehensively restructure their interior to promote the faithful inheritance of DNA and cytoplasmic contents. In metazoans, this restructuring entails disassembly of the nuclear envelope, redistribution of its components into the endoplasmic reticulum (ER) and eventually nuclear envelope reassembly around the segregated chromosomes. The microtubule cytoskeleton has recently emerged as a critical regulator of mitotic nuclear envelope and ER dynamics. Microtubules and associated molecular motors tear open the nuclear envelope in prophase and remove nuclear envelope remnants from chromatin. Additionally, two distinct mechanisms of microtubule-based regulation of ER dynamics operate later in mitosis. First, association of the ER with microtubules is reduced, preventing invasion of ER into the spindle area, and second, organelle membrane is actively cleared from metaphase chromosomes. However, we are only beginning to understand the role of microtubules in shaping and distributing ER and other organelles during mitosis.

  18. Acetylation dynamics of human nuclear proteins during the ionizing radiation-induced DNA damage response

    DEFF Research Database (Denmark)

    Bennetzen, Martin; Andersen, J.S.; Lasen, D.H.

    2013-01-01

    -dependent posttranslational modifications (PT Ms). To complement our previous analysis of IR-induced temporal dynamics of nuclear phosphoproteome, we now identify a range of human nuclear proteins that are dynamically regulated by acetylation, and predominantly deacetylation, during IR-induced DDR by using mass spectrometry......-based proteomic approaches. Apart from cataloging acetylation sites through SILAC proteomic analyses before IR and at 5 and 60 min after IR exposure of U2OS cells, we report that: (1) key components of the transcriptional machinery, such as EP 300 and CREBBP, are dynamically acetylated; (2) that nuclear...... to assess lysine acetylation status and thereby validate the mass spectrometry data. We thus present evidence that nuclear proteins, including those known to regulate cellular functions via epigenetic modifications of histones, are regulated by (de)acetylation in a timely manner upon cell's exposure...

  19. Non-Hermitian bidirectional robust transport

    Science.gov (United States)

    Longhi, Stefano

    2017-01-01

    Transport of quantum or classical waves in open systems is known to be strongly affected by non-Hermitian terms that arise from an effective description of system-environment interaction. A simple and paradigmatic example of non-Hermitian transport, originally introduced by Hatano and Nelson two decades ago [N. Hatano and D. R. Nelson, Phys. Rev. Lett. 77, 570 (1996), 10.1103/PhysRevLett.77.570], is the hopping dynamics of a quantum particle on a one-dimensional tight-binding lattice in the presence of an imaginary vectorial potential. The imaginary gauge field can prevent Anderson localization via non-Hermitian delocalization, opening up a mobility region and realizing robust transport immune to disorder and backscattering. Like for robust transport of topologically protected edge states in quantum Hall and topological insulator systems, non-Hermitian robust transport in the Hatano-Nelson model is unidirectional. However, there is not any physical impediment to observe robust bidirectional non-Hermitian transport. Here it is shown that in a quasi-one-dimensional zigzag lattice, with non-Hermitian (imaginary) hopping amplitudes and a synthetic gauge field, robust transport immune to backscattering can occur bidirectionally along the lattice.

  20. Nuclear Dynamics Consequence Analysis (NDCA) for the Disposal of Spent Nuclear Fuel in an Underground Geologic Repository - Volume 3: Appendices

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, L.L.; Wilson, J.R. (INEEL); Sanchez, L.C.; Aguilar, R.; Trellue, H.R.; Cochrane, K. (SNL); Rath, J.S. (New Mexico Engineering Research Institute)

    1998-10-01

    The United States Department of Energy Office of Environmental Management's (DOE/EM's) National Spent Nuclear Fuel Program (NSNFP), through a collaboration between Sandia National Laboratories (SNL) and Idaho National Engineering and Environmental Laboratory (INEEL), is conducting a systematic Nuclear Dynamics Consequence Analysis (NDCA) of the disposal of SNFs in an underground geologic repository sited in unsaturated tuff. This analysis is intended to provide interim guidance to the DOE for the management of the SNF while they prepare for final compliance evaluation. This report presents results from a Nuclear Dynamics Consequence Analysis (NDCA) that examined the potential consequences and risks of criticality during the long-term disposal of spent nuclear fuel owned by DOE-EM. This analysis investigated the potential of post-closure criticality, the consequences of a criticality excursion, and the probability frequency for post-closure criticality. The results of the NDCA are intended to provide the DOE-EM with a technical basis for measuring risk which can be used for screening arguments to eliminate post-closure criticality FEPs (features, events and processes) from consideration in the compliance assessment because of either low probability or low consequences. This report is composed of an executive summary (Volume 1), the methodology and results of the NDCA (Volume 2), and the applicable appendices (Volume 3).

  1. Fission dynamics: The quest of a temperature dependent nuclear viscosity

    Directory of Open Access Journals (Sweden)

    Vardaci E.

    2013-12-01

    Full Text Available This contribution presents a journey within the open questions about the current use of a temperature dependent nuclear viscosity in models of nuclear fission and proposes an alternative experimental approach by using systems of intermediate fissility. This study is particularly relevant because: i systems of intermediate fissility offer a suitable framework since the intervals between the compound nucleus and scission point temperatures with increasing excitation energy are much smaller than in the case of heavier systems, ii the measurement of observables in the ER channel translates into a larger set of effective constraints for the models.

  2. Motility states in bidirectional cargo transport

    CERN Document Server

    Klein, Sarah; Santen, Ludger

    2015-01-01

    Intracellular cargos which are transported by molecular motors move stochastically along cytoskeleton filaments. In particular for bidirectionally transported cargos it is an open question whether the characteristics of their motion can result from pure stochastic fluctuations or whether some coordination of the motors is needed. The results of a mean-field model of cargo-motors dynamics, which was proposed by M\\"uller et al.[1] suggest the existence of high motility states which would result from a stochastic tug-of-war. Here we analyze a non-mean field extension of their model, that takes explicitly the position of each motor into account. We find that high motility states then disappear. We consider also a mutual motor-motor activation, as an explicit mechanism of motor coordination. We show that the results of the mean-field model are recovered only in case of a strong motor-motor activation in the limit of a high number of motors.

  3. Compartmental analysis of dynamic nuclear medicine data: models and identifiability

    Science.gov (United States)

    Delbary, Fabrice; Garbarino, Sara; Vivaldi, Valentina

    2016-12-01

    Compartmental models based on tracer mass balance are extensively used in clinical and pre-clinical nuclear medicine in order to obtain quantitative information on tracer metabolism in the biological tissue. This paper is the first of a series of two that deal with the problem of tracer coefficient estimation via compartmental modelling in an inverse problem framework. Specifically, here we discuss the identifiability problem for a general n-dimension compartmental system and provide uniqueness results in the case of two-compartment and three-compartment compartmental models. The second paper will utilize this framework in order to show how nonlinear regularization schemes can be applied to obtain numerical estimates of the tracer coefficients in the case of nuclear medicine data corresponding to brain, liver and kidney physiology.

  4. JINA Workshop Nuclear Physics in Hot Dense Dynamic Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Kritcher, A L; Cerjan, C; Landen, O; Libby, S; Chen, M; Wilson, B; Knauer, J; Mcnabb, D; Caggiano, J; Bleauel, D; Weideking, M; Kozhuharov, C; Brandau, C; Stoehlker, T; Meot, V; Gosselin, G; Morel, P; Schneider, D; Bernstein, L A

    2011-03-07

    Measuring NEET and NEEC is relevant for probing stellar cross-sections and testing atomic models in hot plasmas. Using NEEC and NEET we can excite nuclear levels in laboratory plasmas: (1) NIF: Measure effect of excited nuclear levels on (n,{gamma}) cross-sections, 60% and never been measured; (2) Omega, Test cross-sections for creating these excited levels via NEEC and NEET. Will allow us to test models that estimate resonance overlap of atomic states with the nucleus: (1) Average Atom model (AA) (CEA&LLNL), single average wave-function potential; (2) Super Transition Array (STA) model (LLNL), More realistic individual configuration potentials NEET experimental data is scarce and not in a plasma environment, NEEC has not yet been observed.

  5. Fission Dynamics: The Quest of a Temperature Dependent Nuclear Viscosity

    Directory of Open Access Journals (Sweden)

    E. Vardaci

    2013-08-01

    Full Text Available This paper presents a journey within some open questions about the current use of a temperature dependent nuclear viscosity in models of nuclear fission and proposes an alternative experimental approach by using systems of intermediate fissility. This study is particularly relevant because: i systems of intermediate fissility offer a suitable frame-work since the intervals between the compound nucleus and scission point temperatures with increasing excitation energy are much smaller than in the case of heavier systems, ii the dependence of viscosity on the temperature may change with the fissility of the composite system; iii the opportunity to measure also observables in the evaporation residues channel translates into a larger set of effective constraints for the models.

  6. A simple dynamic model and transient simulation of the nuclear power reactor on microcomputers

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yang Gee; Park, Cheol [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    A simple dynamic model is developed for the transient simulation of the nuclear power reactor. The dynamic model includes the normalized neutron kinetics model with reactivity feedback effects and the core thermal-hydraulics model. The main objective of this paper demonstrates the capability of the developed dynamic model to simulate various important variables of interest for a nuclear power reactor transient. Some representative results of transient simulations show the expected trends in all cases, even though no available data for comparison. In this work transient simulations are performed on a microcomputer using the DESIRE/N96T continuous system simulation language which is applicable to nuclear power reactor transient analysis. 3 refs., 9 figs. (Author)

  7. Dynamic nuclear polarization and optimal control spatial-selective 13C MRI and MRS

    DEFF Research Database (Denmark)

    Vinding, Mads Sloth; Laustsen, Christoffer; Maximov, Ivan I.

    2013-01-01

    Aimed at 13C metabolic magnetic resonance imaging (MRI) and spectroscopy (MRS) applications, we demonstrate that dynamic nuclear polarization (DNP) may be combined with optimal control 2D spatial selection to simultaneously obtain high sensitivity and well-defined spatial restriction. This is ach......Aimed at 13C metabolic magnetic resonance imaging (MRI) and spectroscopy (MRS) applications, we demonstrate that dynamic nuclear polarization (DNP) may be combined with optimal control 2D spatial selection to simultaneously obtain high sensitivity and well-defined spatial restriction....... This is achieved through the development of spatial-selective single-shot spiral-readout MRI and MRS experiments combined with dynamic nuclear polarization hyperpolarized [1-13C]pyruvate on a 4.7T pre-clinical MR scanner. The method stands out from related techniques by facilitating anatomic shaped region...

  8. Efficient and dynamic nuclear localization of green fluorescent protein via RNA binding

    Energy Technology Data Exchange (ETDEWEB)

    Kitamura, Akira; Nakayama, Yusaku; Kinjo, Masataka, E-mail: kinjo@sci.hokudai.ac.jp

    2015-07-31

    Classical nuclear localization signal (NLS) sequences have been used for artificial localization of green fluorescent protein (GFP) in the nucleus as a positioning marker or for measurement of the nuclear-cytoplasmic shuttling rate in living cells. However, the detailed mechanism of nuclear retention of GFP-NLS remains unclear. Here, we show that a candidate mechanism for the strong nuclear retention of GFP-NLS is via the RNA-binding ability of the NLS sequence. GFP tagged with a classical NLS derived from Simian virus 40 (GFP-NLS{sup SV40}) localized not only in the nucleoplasm, but also to the nucleolus, the nuclear subdomain in which ribosome biogenesis takes place. GFP-NLS{sup SV40} in the nucleolus was mobile, and intriguingly, the diffusion coefficient, which indicates the speed of diffusing molecules, was 1.5-fold slower than in the nucleoplasm. Fluorescence correlation spectroscopy (FCS) analysis showed that GFP-NLS{sup SV40} formed oligomers via RNA binding, the estimated molecular weight of which was larger than the limit for passive nuclear export into the cytoplasm. These findings suggest that the nuclear localization of GFP-NLS{sup SV40} likely results from oligomerization mediated via RNA binding. The analytical technique used here can be applied for elucidating the details of other nuclear localization mechanisms, including those of several types of nuclear proteins. In addition, GFP-NLS{sup SV40} can be used as an excellent marker for studying both the nucleoplasm and nucleolus in living cells. - Highlights: • Nuclear localization signal-tagged GFP (GFP-NLS) showed clear nuclear localization. • The GFP-NLS dynamically localized not only in the nucleoplasm, but also to the nucleolus. • The nuclear localization of GFP-NLS results from transient oligomerization mediated via RNA binding. • Our NLS-tagging procedure is ideal for use in artificial sequestration of proteins in the nucleus.

  9. Level-one modules library for DSNP: Dynamic Simulator for Nuclear Power-plants

    Energy Technology Data Exchange (ETDEWEB)

    Saphier, D.

    1978-09-01

    The Dynamic Simulator for Nuclear Power-plants (DSNP) is a system of programs and data sets by which a nuclear power plant or part thereof can be simulated at different levels of sophistication. The acronym DSNP is used interchangeably for the DSNP language, for the DSNP precompiler, for the DSNP libraries, and for the DSNP document generator. The DSNP language is a set of simple block oriented statements, which together with the appropriate data, comprise a simulation of a nuclear power plant. The majority of the DSNP statements will result in the inclusion of a simulated physical module into the program. FORTRAN statements can be inserted with no restrictions among DSNP statements.

  10. The use of dynamic nuclear polarization (13)C-pyruvate MRS in cancer

    DEFF Research Database (Denmark)

    Gutte, Henrik; Hansen, Adam Espe; Johannesen, Helle Hjorth

    2015-01-01

    (MRS) is a potent technique for non-invasive in vivo investigation of tissue chemistry and cellular metabolism. Hyperpolarization by Dynamic Nuclear Polarization (DNP) is capable of creating solutions of molecules with polarized nuclear spins in a range of biological molecules and has enabled the real......-time investigation of in vivo metabolism. The development of this new method has been demonstrated to enhance the nuclear polarization more than 10,000-fold, thereby significantly increasing the sensitivity of the MRS with a spatial resolution to the millimeters and a temporal resolution at the subsecond range...

  11. Quantum Trajectory-Electronic Structure Approach for Exploring Nuclear Effects in the Dynamics of Nanomaterials.

    Science.gov (United States)

    Garashchuk, Sophya; Jakowski, Jacek; Wang, Lei; Sumpter, Bobby G

    2013-12-10

    A massively parallel, direct quantum molecular dynamics method is described. The method combines a quantum trajectory (QT) representation of the nuclear wave function discretized into an ensemble of trajectories with an electronic structure (ES) description of electrons, namely using the density functional tight binding (DFTB) theory. Quantum nuclear effects are included into the dynamics of the nuclei via quantum corrections to the classical forces. To reduce computational cost and increase numerical accuracy, the quantum corrections to dynamics resulting from localization of the nuclear wave function are computed approximately and included into selected degrees of freedom representing light particles where the quantum effects are expected to be the most pronounced. A massively parallel implementation, based on the message passing interface allows for efficient simulations of ensembles of thousands of trajectories at once. The QTES-DFTB dynamics approach is employed to study the role of quantum nuclear effects on the interaction of hydrogen with a model graphene sheet, revealing that neglect of nuclear effects can lead to an overestimation of adsorption.

  12. Nuclear mean field from chiral pion-nucleon dynamics

    CERN Document Server

    Kaiser, N; Weise, W

    2002-01-01

    Using the two-loop approximation of chiral perturbation theory, we calculate the momentum- and density-dependent single-particle potential of nucleons in isospin-symmetric nuclear matter. The contributions from one- and two-pion exchange diagrams give rise to a potential depth for a nucleon at rest of U(0,k sub f sub 0)=-53.2 MeV at saturation density. The momentum dependence of the real part of the single-particle potential U(p,k sub f sub 0) is nonmonotonic and can be translated into a mean effective nucleon mass of M*bar approx =0.8M. The imaginary part of the single-particle potential W(p,k sub f) is generated to that order entirely by iterated one-pion exchange. The resulting half width of a nucleon hole-state at the bottom of the Fermi sea comes out as W(0,k sub f sub 0)=29.7 MeV. The basic theorems of Hugenholtz-Van-Hove and Luttinger are satisfied in our perturbative two-loop calculation of the nuclear mean field.

  13. Molecular dynamics-based selectivity for Fast-Field-Cycling relaxometry by Overhauser and solid effect dynamic nuclear polarization

    Science.gov (United States)

    Neudert, Oliver; Mattea, Carlos; Stapf, Siegfried

    2017-03-01

    In the last decade nuclear spin hyperpolarization methods, especially Dynamic Nuclear Polarization (DNP), have provided unprecedented possibilities for various NMR techniques by increasing the sensitivity by several orders of magnitude. Recently, in-situ DNP-enhanced Fast Field Cycling (FFC) relaxometry was shown to provide appreciable NMR signal enhancements in liquids and viscous systems. In this work, a measurement protocol for DNP-enhanced NMR studies is introduced which enables the selective detection of nuclear spin hyperpolarized by either Overhauser effect or solid effect DNP. Based on field-cycled DNP and relaxation studies it is shown that these methods allow for the independent measurement of polymer and solvent nuclear spins in a concentrated solution of high molecular weight polybutadiene in benzene doped with α,γ-bisdiphenylene-β-phenylallyl radical. Appreciable NMR signal enhancements of about 10-fold were obtained for both constituents. Moreover, qualitative information about the dynamics of the radical and solvent was obtained. Selective DNP-enhanced FFC relaxometry is applied for the measurement of the 1H nuclear magnetic relaxation dispersion of both constituents with improved precision. The introduced method is expected to greatly facilitate NMR studies of complex systems with multiple overlapping signal contributions that cannot be distinguished by standard methods.

  14. Study on the dynamic response analysis for evaluating the effectiveness of base isolation for nuclear components

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Kazunari; Tsutsumi, Hideaki; Yamada, Hiroyuki; Ebisawa, Katsumi; Shibata, Katsuyuki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-07-01

    Introduction of the base isolation technique into the seismic design of nuclear power plant components as well as buildings has been expected as one of the effective countermeasure to reduce the seismic force applied to components. A research program on the base isolation of nuclear components has been carried out at the Japan Atomic Energy Research Institute (JAERI) since 1991. A methodology and a computer code (EBISA: Equipment Base Insolation System Analysis) for evaluating the failure frequency of the nuclear component with the base isolation were developed. In addition, a test program, which is concerned with the above development, aiming at improvement of failure frequency analysis models in the code has been conducted since 1996 to investigate the dynamic behavior and to verify the effectiveness of component base isolation systems. In the failure frequency analysis, methodology for evaluating the actual dynamic responses of the nuclear components with the base isolation in detail has been examined. In the methodology, the actual responses are computed by considering the scatter in mechanical properties of rock masses, reactor building and components under many earthquake motions with various frequency characteristics. The failure frequency of component is computed as the conditional probability where the actual response exceeds the capacity of components. It is a very important in the above methodology to investigates the dynamic response analysis method for the ground, reactor building and nuclear components as well as the scattering factors in the dynamic analysis. This report describes the accuracy of the dynamic response analysis method and analysis models, and the influence of scatters in properties of rock masses and reactor building on the dynamic response. (author)

  15. Dynamics of nuclear matrix proteome during embryonic development in Drosophila melanogaster

    Indian Academy of Sciences (India)

    Parul Varma; Rakesh K Mishra

    2011-08-01

    Embryonic development is a complex and dynamic process that involves spatiotemporal expression of genes in a highly coordinated manner. Multiple levels of nuclear architecture maintain the fidelity of gene expression programme. One of the components of nuclear architecture, which is believed to play an important role in regulation of gene expression, is the nuclear matrix (NuMat). Many studies over the past few years have tried to analyse the components of this non-chromatin scaffolding of the nucleus and have provided evidences of its structural and functional complexity. However, the relationship of NuMat with the process of embryonic development still remains poorly understood. Here, we report a comparative analysis of the NuMat proteomes of early and late stage Drosophila melanogaster embryos and show that 65% of the NuMat proteome is dynamic during development. Our study establishes links between the dynamics of nuclear architecture and embryonic development and provides tools to further understand the process such as cellular differentiation in the context of higher-order nuclear organization.

  16. Cell cycle-dependent alteration in NAC1 nuclear body dynamics and morphology

    Science.gov (United States)

    Wu, Pei-Hsun; Hung, Shen-Hsiu; Ren, Tina; Shih, Ie-Ming; Tseng, Yiider

    2011-02-01

    NAC1, a BTB/POZ family member, has been suggested to participate in maintaining the stemness of embryonic stem cells and has been implicated in the pathogenesis of human cancer. In ovarian cancer, NAC1 upregulation is associated with disease aggressiveness and with the development of chemoresistance. Like other BTB/POZ proteins, NAC1 forms discrete nuclear bodies in non-dividing cells. To investigate the biological role of NAC1 nuclear bodies, we characterized the expression dynamics of NAC1 nuclear bodies during different phases of the cell cycle. Fluorescence recovery after photobleaching assays revealed that NAC1 was rapidly exchanged between the nucleoplasm and NAC1 nuclear bodies in interphase cells. The number of NAC1 bodies significantly increased and their size decreased in the S phase as compared to the G0/G1 and G2 phases. NAC1 nuclear bodies disappeared and NAC1 became diffuse during mitosis. NAC1 nuclear bodies reappeared immediately after completion of mitosis. These results indicate that a cell cycle-dependent regulatory mechanism controls NAC1 body formation in the nucleus and suggest that NAC1 body dynamics are associated with mitosis or cytokinesis.

  17. Shamir secret sharing scheme with dynamic access structure (SSSDAS). Case study on nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Thiyagarajan, P.; Thandra, Prasanth Kumar; Rajan, J.; Satyamurthy, S.A.V. [Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam (India). Computer Div.; Aghila, G. [National Institute of Technology, Karaikal (India). Dept. of Computer Science and Engineering

    2015-05-15

    In recent years, due to the sophistication offered by the Internet, strategic organizations like nuclear power plants are linked to the outside world communication through the Internet. The entry of outside world communication into strategic organization (nuclear power plant) increases the hacker's attempts to crack its security and to trace any information which is being sent among the top level officials. Information security system in nuclear power plant is very crucial as even small loophole in the security system will lead to a major disaster. Recent cyber attacks in nuclear power plant provoked information security professionals to look deeply into the information security aspects of strategic organizations (nuclear power plant). In these lines, Shamir secret sharing scheme with dynamic access structure (SSSDAS) is proposed in the paper which provides enhanced security by providing dynamic access structure for each node in different hierarchies. The SSSDAS algorithm can be applied to any strategic organizations with hierarchical structures. In this paper the possible scenarios where SSSDAS algorithm can be applied to nuclear power plant is explained as a case study. The proposed SSSDAS scheme identifies the wrong shares, if any, used for reconstruction of the secret. The SSSDAS scheme also address the three major security parameters namely confidentiality, authentication and integrity.

  18. Bidirectional power converter control electronics

    Science.gov (United States)

    Mildice, J. W.

    1987-01-01

    The object of this program was to design, build, test, and deliver a set of control electronics suitable for control of bidirectional resonant power processing equipment of the direct output type. The program is described, including the technical background, and results discussed. Even though the initial program tested only the logic outputs, the hardware was subsequently tested with high-power breadboard equipment, and in the testbed of NASA contract NAS3-24399. The completed equipment is now operating as part of the Space Station Power System Test Facility at NASA Lewis Research Center.

  19. Validation of Infinite Impulse Response Multilayer Perceptron for Modelling Nuclear Dynamics

    Directory of Open Access Journals (Sweden)

    F. Cadini

    2008-01-01

    Full Text Available Artificial neural networks are powerful algorithms for constructing nonlinear empirical models from operational data. Their use is becoming increasingly popular in the complex modeling tasks required by diagnostic, safety, and control applications in complex technologies such as those employed in the nuclear industry. In this paper, the nonlinear modeling capabilities of an infinite impulse response multilayer perceptron (IIR-MLP for nuclear dynamics are considered in comparison to static modeling by a finite impulse response multilayer perceptron (FIR-MLP and a conventional static MLP. The comparison is made with respect to the nonlinear dynamics of a nuclear reactor as investigated by IIR-MLP in a previous paper. The superior performance of the locally recurrent scheme is demonstrated.

  20. Dynamical Behavior of Core 3 He Nuclear Reaction-Diffusion Systems and Sun's Gravitational Field

    Institute of Scientific and Technical Information of China (English)

    DU Jiulin; SHEN Hong

    2005-01-01

    The coupling of the sun's gravitational field with processes of diffusion and convection exerts a significant influence on the dynamical behavior of the core 3He nuclear reaction-diffusion system. Stability analyses of the system are made in this paper by using the theory of nonequilibrium dynamics. It is showed that, in the nuclear reaction regions extending from the center to about 0.38 times of the radius of the sun, the gravitational field enables the core 3He nuclear reaction-diffusion system to become unstable and, after the instability, new states to appear in the system have characteristic of time oscillation. This may change the production rates of both 7Be and 8B neutrinos.

  1. Nuclear dynamical correlation effects in X-ray spectroscopy from a time-domain perspective

    CERN Document Server

    Karsten, Sven; Aziz, Saadullah G; Bokarev, Sergey I; Kühn, Oliver

    2016-01-01

    To date X-ray spectroscopy has become a routine tool that can reveal highly local and element-specific information on the electronic structure of atoms in complex environments. Here, we focus on nuclear dynamical effects in X-ray spectra and develop a rigorous time-correlation method employing ground state molecular dynamics simulations. The importance of nuclear correlation phenomena is demonstrated by comparison against the results from the conventional sampling approach for gas phase water. In contrast to the first-order absorption, second-order resonant inelastic scattering spectra exhibit pronounced fingerprints of nuclear motions. The developed methodology does not depend on the accompanying electronic structure method in principle as well as on the spectral range and, thus, can be applied to, e.g., UV and X-ray photo-electron and Auger spectroscopies.

  2. Dynamic nuclear magnetic resonance field sensing with part-per-trillion resolution

    Science.gov (United States)

    Gross, Simon; Barmet, Christoph; Dietrich, Benjamin E.; Brunner, David O.; Schmid, Thomas; Pruessmann, Klaas P.

    2016-12-01

    High-field magnets of up to tens of teslas in strength advance applications in physics, chemistry and the life sciences. However, progress in generating such high fields has not been matched by corresponding advances in magnetic field measurement. Based mostly on nuclear magnetic resonance, dynamic high-field magnetometry is currently limited to resolutions in the nanotesla range. Here we report a concerted approach involving tailored materials, magnetostatics and detection electronics to enhance the resolution of nuclear magnetic resonance sensing by three orders of magnitude. The relative sensitivity thus achieved amounts to 1 part per trillion (10-12). To exemplify this capability we demonstrate the direct detection and relaxometry of nuclear polarization and real-time recording of dynamic susceptibility effects related to human heart function. Enhanced high-field magnetometry will generally permit a fresh look at magnetic phenomena that scale with field strength. It also promises to facilitate the development and operation of high-field magnets.

  3. Widths of K¯-nuclear deeply bound states in a dynamical model

    Science.gov (United States)

    Mareš, J.; Friedman, E.; Gal, A.

    2005-01-01

    The relativistic mean field (RMF) model is applied to a system of nucleons and a Kbar meson, interacting via scalar and vector boson fields. The model incorporates the standard RMF phenomenology for bound nucleons and, for the Kbar meson, it relates to low-energy Kbar N and K- atom phenomenology. Deeply bound Kbar nuclear states are generated dynamically across the periodic table and are exhibited for 12C and 16O over a wide range of binding energies. Substantial polarization of the core nucleus is found for these light nuclei. Absorption modes are also included dynamically, considering explicitly both the resulting compressed nuclear density and the reduced phase space for Kbar absorption from deeply bound states. The behavior of the calculated width as function of the Kbar binding energy is studied in order to explore limits on the possible existence of narrow Kbar nuclear states.

  4. Waveguide transition with vacuum window for multiband dynamic nuclear polarization systems

    DEFF Research Database (Denmark)

    Rybalko, Oleksandr; Bowen, Sean; Zhurbenko, Vitaliy

    2016-01-01

    A low loss waveguide transition section and oversized microwave vacuum window covering several frequency bands (94 GHz, 140 GHz, 188 GHz) is presented. The transition is compact and was optimized for multiband Dynamic Nuclear Polarization (DNP) systems in a full-wave simulator. The window is more...

  5. Formulation and utilization of choline based samples for dissolution dynamic nuclear polarization

    DEFF Research Database (Denmark)

    Bowen, Sean; Ardenkjær-Larsen, Jan Henrik

    2013-01-01

    Hyperpolarization by the dissolution dynamic nuclear polarization (DNP) technique permits the generation of high spin polarization of solution state. However, sample formulation for dissolution-DNP is often difficult, as concentration and viscosity must be optimized to yield a dissolved sample...

  6. Dynamic Operations Wayfinding System (DOWS) for Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Boring, Ronald Laurids [Idaho National Laboratory; Ulrich, Thomas Anthony [Idaho National Laboratory; Lew, Roger Thomas [Idaho National Laboratory

    2015-08-01

    A novel software tool is proposed to aid reactor operators in respond- ing to upset plant conditions. The purpose of the Dynamic Operations Wayfind- ing System (DOWS) is to diagnose faults, prioritize those faults, identify paths to resolve those faults, and deconflict the optimal path for the operator to fol- low. The objective of DOWS is to take the guesswork out of the best way to combine procedures to resolve compound faults, mitigate low threshold events, or respond to severe accidents. DOWS represents a uniquely flexible and dy- namic computer-based procedure system for operators.

  7. Nuclear dynamics of radiation-induced foci in euchromatin and heterochromatin

    Energy Technology Data Exchange (ETDEWEB)

    Chiolo, Irene; Georgescu, Walter; Tang, Jonathan; Costes, Sylvain V.

    2013-09-03

    Repair of double strand breaks (DSBs) is essential for cell survival and genome integrity. While much is known about the molecular mechanisms involved in DSB repair and checkpoint activation, the roles of nuclear dynamics of radiation-induced foci (RIF) in DNA repair are just beginning to emerge. Here, we summarize results from recent studies that point to distinct features of these dynamics in two different chromatin environments: heterochromatin and euchromatin. We also discuss how nuclear architecture and chromatin components might control these dynamics, and the need of novel quantification methods for a better description and interpretation of these phenomena. These studies are expected to provide new biomarkers for radiation risk and new strategies for cancer detection and treatment.

  8. Nuclear dynamics of radiation-induced foci in euchromatin and heterochromatin

    Energy Technology Data Exchange (ETDEWEB)

    Chiolo, Irene; Tang, Jonathan; Georgescu, Walter; Costes, Sylvain V.

    2013-10-01

    Repair of double strand breaks (DSBs) is essential for cell survival and genome integrity. While much is known about the molecular mechanisms involved in DSB repair and checkpoint activation, the roles of nuclear dynamics of radiation-induced foci (RIF) in DNA repair are just beginning to emerge. Here, we summarize results from recent studies that point to distinct features of these dynamics in two different chromatin environments: heterochromatin and euchromatin. We also discuss how nuclear architecture and chromatin components might control these dynamics, and the need of novel quantification methods for a better description and interpretation of these phenomena. These studies are expected to provide new biomarkers for radiation risk and new strategies for cancer detection and treatment.

  9. Personalized recommendation based on preferential bidirectional mass diffusion

    Science.gov (United States)

    Chen, Guilin; Gao, Tianrun; Zhu, Xuzhen; Tian, Hui; Yang, Zhao

    2017-03-01

    Recommendation system provides a promising way to alleviate the dilemma of information overload. In physical dynamics, mass diffusion has been used to design effective recommendation algorithms on bipartite network. However, most of the previous studies focus overwhelmingly on unidirectional mass diffusion from collected objects to uncollected objects, while overlooking the opposite direction, leading to the risk of similarity estimation deviation and performance degradation. In addition, they are biased towards recommending popular objects which will not necessarily promote the accuracy but make the recommendation lack diversity and novelty that indeed contribute to the vitality of the system. To overcome the aforementioned disadvantages, we propose a preferential bidirectional mass diffusion (PBMD) algorithm by penalizing the weight of popular objects in bidirectional diffusion. Experiments are evaluated on three benchmark datasets (Movielens, Netflix and Amazon) by 10-fold cross validation, and results indicate that PBMD remarkably outperforms the mainstream methods in accuracy, diversity and novelty.

  10. Chaotic features of nuclear structure and dynamics: selected topics

    Science.gov (United States)

    Zelevinsky, Vladimir; Volya, Alexander

    2016-03-01

    Quantum chaos has become an important element of our knowledge about physics of complex systems. In typical mesoscopic systems of interacting particles the dynamics invariably become chaotic when the level density, growing by combinatorial reasons, leads to the increasing probability of mixing simple mean-field (particle-hole) configurations. The resulting stationary states have exceedingly complicated structures that are comparable to those in random matrix theory. We discuss the main properties of mesoscopic quantum chaos and show that it can serve as a justification for application of statistical mechanics to mesoscopic systems. We show that quantum chaos becomes a powerful instrument for experimental, theoretical and computational work. The generalization to open systems and effects in the continuum are discussed with the help of the effective non-Hermitian Hamiltonian; it is shown how to formulate this approach for numerous problems of quantum signal transmission. The artificially introduced randomness can also be helpful for a deeper understanding of physics. We indicate the problems that require more investigation so as to be understood further.

  11. Alignment dependent ultrafast electron-nuclear dynamics in high-order harmonic generation

    CERN Document Server

    Li, Mu-Zi; Bian, Xue-Bin

    2016-01-01

    We investigated the high-order harmonic generation (HHG) process of diatomic molecular ion $\\mathrm{H}_2^+$ in non-Born-Oppenheimer approximations. The corresponding three-dimensional time-dependent Schr\\"odinger equation is solved with arbitrary alignment angles. It is found that the nuclear motion can lead to spectral modulation of HHG. Redshifts are unique in molecular HHG which decrease with the increase of alignment angles of the molecules and are sensitive to the initial vibrational states. It can be used to extract the ultrafast electron-nuclear dynamics and image molecular structure.

  12. Site Earthquake Characteristics and Dynamic Parameter Test of Phase Ⅲ Qinshan Nuclear Power Engineering

    Institute of Scientific and Technical Information of China (English)

    ZHOV Nian-qing; ZHAO Zai-li; QIN Min

    2009-01-01

    The earthquake characteristics and geological structure of the site to sitting the Qinshan Nuclear Power Station are closely related. According to site investigation drilling, sampling, seismic sound logging wave test in single-hole and cross-hole, laboratory wave velocity test of intact rock, together with analysis of the site geological conditions, the seismic wave test results of the site between strata lithology and the geologic structure were studied. The relationships of seismic waves with the site lithology and the geologic structure were set up.The dynamic parameters of different grades of weathering profile were deduced. The results assist the seismic design of Phase Ⅲ Qinshan Nuclear Power Plant, China.

  13. Dynamic nuclear polarization and relaxation of H and D atoms in solid mixtures of hydrogen isotopes

    CERN Document Server

    Sheludiakov, S; Järvinen, J; Vainio, O; Lehtonen, L; Vasiliev, S; Lee, D M; Khmelenko, V V

    2016-01-01

    We report on a study of Dynamic Nuclear Polarization and electron and nuclear spin relaxation of atomic hydrogen and deuterium in solid molecular matrices of H$_{2}$, D$_{2}$, and HD mixtures. The electron and nuclear spin relaxation times ($T_{1e}$ and $T_{1N}$) were measured within the temperature range 0.15-2.5$\\,$K in a magnetic field of 4.6 T, conditions which ensure a high polarization of electron spins. We found that $T_{1e}$ is nearly temperature independent in this temperature range, while $T_{1N}$ decreased by 2 orders of magnitude. Such strong temperature dependence is typical for the nuclear Orbach mechanism of relaxation via the electron spins. We found that the nuclear spins of H atoms in solid D$_{2}$ and D$_{2}:$HD can be efficiently polarized by the Overhauser effect. Pumping the forbidden transitions of H atoms also leads to DNP, with the efficiency strongly dependent on the concentration of D atoms. This behaviour indicates the Cross effect mechanism of the DNP and nuclear relaxation, which...

  14. Solid effect in the electron spin dressed state: A new approach for dynamic nuclear polarization

    Science.gov (United States)

    Weis, V.; Bennati, M.; Rosay, M.; Griffin, R. G.

    2000-10-01

    We describe a new type of solid effect for dynamic nuclear polarization (DNP) that is based on simultaneous, near resonant microwave (mw) and radio frequency (rf) irradiation of a coupled electron nuclear spin system. The interaction of the electron spin with the mw field is treated as an electron spin dressed state. In contrast to the customary laboratory frame solid effect, it is possible to obtain nuclear polarization with the dressed state solid effect (DSSE) even in the absence of nonsecular hyperfine coupling. Efficient, selective excitation of dressed state transitions generates nuclear polarization in the nuclear laboratory frame on a time scale of tens of μs, depending on the strength of the electron-nuclear coupling, the mw and rf offset and field strength. The experiment employs both pulsed mw and rf irradiation at a repetition rate comparable to T1e-1, where T1e is the electronic spin lattice relaxation time. The DSSE is demonstrated on a perdeuterated BDPA radical in a protonated matrix of polystyrene.

  15. Dynamical safety assessment of the nuclear power plant component using the information feedback oriented system dynamics method

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Tae Ho; Jung, Byung Ryul; Kwak, Sang Man [The Univ. of Illinois at Urbana-Champaign, Urbana (United States)

    2002-05-01

    A feedback oriented dynamical safety assessment in nuclear power plant is constructed. A commercial software for System Dynamics, Ventana Simulation Environment (Vensim), is used to develop a dynamics model for the Auxiliary Feed Water System (AFWS) of Pressurized Water Reactor (PWR). The 18-month refuel cycle is described for the real situation. The failure rate is higher when the plant is in zero power state like maintenance, test, and refueling, which is not well described in conventional Event/Fault Tree based safety assessment. This also means a human failure rate is high in the standby and shutdown states. Time Step is introduced for the different time weighted frequency of failure cases. The Common Cause Failure is affected by Time Step process. The simulation shows dynamically for the standby-running and shutdown-running of nuclear power plant. The modeling is easily made by a unique graphic designed method and understood by operator or reviewer well. The logical and systems thinking is simulated.

  16. Transverse dynamics of hard partons in nuclear media and the QCD dipole

    CERN Document Server

    Wiedemann, Urs Achim

    2000-01-01

    We derive the non-abelian generalization of the Furry approximation whichdescribes the transverse dynamical evolution of a hard projectile parton insidea spatially extended colour target field. This provides a unified startingpoint for the target rest frame description of the nuclear dependence of alarge class of observables. For the case of the virtual gamma -> q qbarphotoabsorption cross section, we investigate in detail under which conditionsthe nuclear dependence encoded in the Furry wavefunctions can be parametrizedby a q-qbar QCD dipole cross section. The important condition is colourtriviality, i.e., the property that for arbitrary N-fold rescatteringcontributions the only non-vanishing colour trace is N_c C_F^N. We give proofsfor the colour triviality of the inelastic, diffractive and totalphotoabsorption cross section measured inclusively or with one jet resolved inthe final state. Also, we list examples for which colour interference effectsremain. Colour triviality allows us to write the DIS nuclear...

  17. 1H and 15N Dynamic Nuclear Polarization Studies of Carbazole

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jian Zhi; Solum, Mark S.; Wind, Robert A.; Nilsson, Brad L.; Peterson, Matt A.; Pugmire, Ronald J.; Grant, David M.

    2000-01-01

    15N NMR experiments, combined with dynamic nuclear polarization (DNP), are reported on carbazole doped with the stable free radical 1,3 bisdiphenylene-2 phenylally1 (BDPA). Doping shortens the nuclear relaxation times and provides paramagnetic centers that can be used to enhance the nuclear signal by means of DNP so that 15 N NMR experiments can be done in minutes. The factors were measured in a 1.4 T external field, using both unlabeled and 98% 15N labeled carbazole with doping levels varying between 0.65 and 5.0 wt % BDPA. A doping level of approximately 1 wt % produced optimal results. DNP enhancement factors of 35 and 930 were obtained for 1H and 15N, respectively making it possible to perform 15N DNP NMR experiments at the natural abundance level.

  18. The use of dynamic nuclear polarization 13C-pyruvate MRS in cancer

    DEFF Research Database (Denmark)

    Borgwardt, Henrik Gutte; Espe Hansen, Adam; Hjort Johannesen, Helle;

    2015-01-01

    In recent years there has been an immense development of new targeted anti-cancer drugs. For practicing precision medicine, a sensitive method imaging for non-invasive, assessment of early treatment response and for assisting in developing new drugs is warranted. Magnetic Resonance Spectroscopy...... (MRS) is a potent technique for non-invasive in vivo investigation of tissue chemistry and cellular metabolism. Hyperpolarization by Dynamic Nuclear Polarization (DNP) is capable of creating solutions of molecules with polarized nuclear spins in a range of biological molecules and has enabled the real......-time investigation of in vivo metabolism. The development of this new method has been demonstrated to enhance the nuclear polarization more than 10,000-fold, thereby significantly increasing the sensitivity of the MRS with a spatial resolution to the millimeters and a temporal resolution at the subsecond range...

  19. Efficient dynamic nuclear polarization of phosphorus in silicon in strong magnetic fields and at low temperatures

    Science.gov (United States)

    Järvinen, J.; Ahokas, J.; Sheludyakov, S.; Vainio, O.; Lehtonen, L.; Vasiliev, S.; Zvezdov, D.; Fujii, Y.; Mitsudo, S.; Mizusaki, T.; Gwak, M.; Lee, SangGap; Lee, Soonchil; Vlasenko, L.

    2014-12-01

    Efficient manipulation of nuclear spins is important for utilizing them as qubits for quantum computing. In this work we report record high polarizations of 31P and 29Si nuclear spins in P-doped silicon in a strong magnetic field (4.6 T) and at temperatures below 1 K. We reached 31P nuclear polarization values exceeding 98 % after 20 min of pumping the high-field electron spin resonance (ESR) line with a very small microwave power of 0.4 μ W . We evaluate that the ratio of the hyperfine-state populations increases by three orders of magnitude after 2 hours of pumping, and an extremely pure nuclear spin state can be created, with less than 0.01 ppb impurities. A negative dynamic nuclear polarization has been observed by pumping the low-field ESR line of 31P followed by the flip-flip cross relaxation, the transition which is fully forbidden for isolated donors. We estimate that while pumping the ESR transitions of 31P also the nuclei of 29Si get polarized, and polarization exceeding 60 % has been obtained. We performed measurements of relaxation rates of flip-flop and flip-flip transitions which turned out to be nearly temperature independent. Temperature dependence of the 31P nuclear relaxation was studied down to 0.75 K, below which the relaxation time became too long to be measured. We found that the polarization evolution under pumping and during relaxation deviates substantially from a simple exponential function of time. We suggest that the nonexponential polarization dynamics of 31P donors is mediated by the orientation of 29Si nuclei, which affect the transition probabilities of the forbidden cross-relaxation processes.

  20. Recent developments in chiral dynamics of hadrons and hadrons in a nuclear medium

    CERN Document Server

    Oset, E; Vacas, M J V; Kaskulov, M; Roca, L; Magas, V K; Ramos, A; Toki, H

    2007-01-01

    In this talk I present recent developments in chiral dynamics of hadrons and hadrons in a medium addressing the following points: interaction of the octet of pseudoscalar mesons with the octet of baryons of the nucleon, showing recent experimental evidence on the existence of two $\\Lambda(1405)$ states, the interaction of the octet of pseudoscalar mesons with the decuplet of baryons of the $\\Delta$, with particular emphasis on the $\\Lambda(1520)$ resonance, dynamically generated by this interaction. Then I review the interaction of kaons in a nuclear medium and briefly discuss the situation around the claims of deeply bound states in nuclei. The large renormalization of the $\\Lambda(1520)$ in the nuclear medium is shown as another example of successful application of the chiral unitary techniques.

  1. Electron momentum spectroscopy of aniline taking account of nuclear dynamics in the initial electronic ground state

    Science.gov (United States)

    Farasat, M.; Shojaei, S. H. R.; Morini, F.; Golzan, M. M.; Deleuze, M. S.

    2016-04-01

    The electronic structure, electron binding energy spectrum and (e, 2e) momentum distributions of aniline have been theoretically predicted at an electron impact energy of 1.500 keV on the basis of Born-Oppenheimer molecular dynamical simulations, in order to account for thermally induced nuclear motions in the initial electronic ground state. Most computed momentum profiles are rather insensitive to thermally induced alterations of the molecular structure, with the exception of the profiles corresponding to two ionization bands at electron binding energies comprised between ˜10.0 and ˜12.0 eV (band C) and between ˜16.5 and ˜20.0 eV (band G). These profiles are found to be strongly influenced by nuclear dynamics in the electronic ground state, especially in the low momentum region. The obtained results show that thermal averaging smears out most generally the spectral fingerprints that are induced by nitrogen inversion.

  2. Fully quantum non-adiabatic dynamics in electronic-nuclear coherent state basis

    CERN Document Server

    Humeniuk, Alexander

    2016-01-01

    Direct dynamics methods using Gaussian wavepackets have to rely only on local properties, such as gradients and hessians at the center of the wavepacket, so as to be compatible with the usual quantum chemistry methods. Matrix elements of the potential energy surfaces between wavepackets therefore usually have to be approximated. It is shown, that if a modified form of valence bond theory is used instead of the usual MO-based theories, the matrix elements can be obtained exactly. This is so because the molecular Hamiltonian only contains the Coulomb potential, for which matrix elements between different basis functions (consisting of Gaussian nuclear and electronic orbitals) are all well-known. In valence bond theory the self-consistent field calculation can be avoided so that the matrix elements are analytical functions of the nuclear coordinates. A method for simulating non-adiabatic quantum dynamics is sketched, where coherent state trajectories are propagated "on the fly" on adiabatic potential energy surf...

  3. Pumping dynamics of nuclear spins in GaAs quantum wells

    CERN Document Server

    Mocek, Raphael W; Cascio, Giovanni; Suter, Dieter

    2016-01-01

    Irradiating a semiconductor with circularly polarized light creates spin-polarized charge carriers. If the material contains atoms with non-zero nuclear spin, they interact with the electron spins via the hyperfine coupling. Here, we consider GaAs/AlGaAs quantum wells, where the conduction-band electron spins interact with three different types of nuclear spins. The hyperfine interaction drives a transfer of spin polarization to the nuclear spins, which therefore acquire a polarization that is comparable to that of the electron spins. In this paper, we analyze the dynamics of the optical pumping process in the presence of an external magnetic field while irradiating a single quantum well with a circularly polarized laser. We measure the time dependence of the photoluminescence polarization to monitor the buildup of the nuclear spin polarization and thus the average hyperfine interaction acting on the electron spins. We present a simple model that adequately describes the dynamics of this process and is in goo...

  4. Varicella-zoster virus induces the formation of dynamic nuclear capsid aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Lebrun, Marielle [University of Liege (ULg), GIGA-Infection Immunity and Inflammation, Laboratory of Virology and Immunology, Liege (Belgium); Thelen, Nicolas; Thiry, Marc [University of Liege (ULg), GIGA-Neurosciences, Laboratory of Cellular and Tissular Biology, Liege (Belgium); Riva, Laura; Ote, Isabelle; Condé, Claude; Vandevenne, Patricia [University of Liege (ULg), GIGA-Infection Immunity and Inflammation, Laboratory of Virology and Immunology, Liege (Belgium); Di Valentin, Emmanuel [University of Liege (ULg), GIGA-Viral Vectors Platform, Liege (Belgium); Bontems, Sébastien [University of Liege (ULg), GIGA-Infection Immunity and Inflammation, Laboratory of Virology and Immunology, Liege (Belgium); Sadzot-Delvaux, Catherine, E-mail: csadzot@ulg.ac.be [University of Liege (ULg), GIGA-Infection Immunity and Inflammation, Laboratory of Virology and Immunology, Liege (Belgium)

    2014-04-15

    The first step of herpesviruses virion assembly occurs in the nucleus. However, the exact site where nucleocapsids are assembled, where the genome and the inner tegument are acquired, remains controversial. We created a recombinant VZV expressing ORF23 (homologous to HSV-1 VP26) fused to the eGFP and dually fluorescent viruses with a tegument protein additionally fused to a red tag (ORF9, ORF21 and ORF22 corresponding to HSV-1 UL49, UL37 and UL36). We identified nuclear dense structures containing the major capsid protein, the scaffold protein and maturing protease, as well as ORF21 and ORF22. Correlative microscopy demonstrated that the structures correspond to capsid aggregates and time-lapse video imaging showed that they appear prior to the accumulation of cytoplasmic capsids, presumably undergoing the secondary egress, and are highly dynamic. Our observations suggest that these structures might represent a nuclear area important for capsid assembly and/or maturation before the budding at the inner nuclear membrane. - Highlights: • We created a recombinant VZV expressing the small capsid protein fused to the eGFP. • We identified nuclear dense structures containing capsid and procapsid proteins. • Correlative microscopy showed that the structures correspond to capsid aggregates. • Procapsids and partial capsids are found within the aggregates of WT and eGFP-23 VZV. • FRAP and FLIP experiments demonstrated that they are dynamic structures.

  5. Monitoring Nonadiabatic Electron-Nuclear Dynamics in Molecules by Attosecond Streaking of Photoelectrons

    CERN Document Server

    Kowalewski, Markus; Rouxel, Jérémy R; Mukamel, Shaul

    2016-01-01

    Streaking of photoelectrons has long been used for the temporal characterization of attosecond extreme ultraviolet pulses. When the time-resolved photoelectrons originate from a coherent superposition of electronic states, they carry an additional phase information, which can be retrieved by the streaking technique. In this contribution we extend the streaking formalism to include coupled electron and nuclear dynamics in molecules as well as initial coherences and demonstrate how it offers a novel tool to monitor non-adiabatic dynamics as it occurs in the vicinity of conical intersections and avoided crossings. Streaking can enhance the time resolution and provide direct signatures of electronic coherences, which affect many primary photochemical and biological events.

  6. Monitoring Nonadiabatic Electron-Nuclear Dynamics in Molecules by Attosecond Streaking of Photoelectrons

    Science.gov (United States)

    Kowalewski, Markus; Bennett, Kochise; Rouxel, Jérémy R.; Mukamel, Shaul

    2016-07-01

    Streaking of photoelectrons has long been used for the temporal characterization of attosecond extreme ultraviolet pulses. When the time-resolved photoelectrons originate from a coherent superposition of electronic states, they carry additional phase information, which can be retrieved by the streaking technique. In this contribution we extend the streaking formalism to include coupled electron and nuclear dynamics in molecules as well as initial coherences. We demonstrate how streaked photoelectrons offer a novel tool for monitoring nonadiabatic dynamics as it occurs in the vicinity of conical intersections and avoided crossings. Streaking can provide high time resolution direct signatures of electronic coherences, which affect many primary photochemical and biological events.

  7. Dynamic flowgraph modeling of process and control systems of a nuclear-based hydrogen production plant

    Energy Technology Data Exchange (ETDEWEB)

    Al-Dabbagh, Ahmad W. [Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, Ontario (Canada); Lu, Lixuan [Faculty of Energy Systems and Nuclear Science, Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, Ontario (Canada)

    2010-09-15

    Modeling and analysis of system reliability facilitate the identification of areas of potential improvement. The Dynamic Flowgraph Methodology (DFM) is an emerging discrete modeling framework that allows for capturing time dependent behaviour, switching logic and multi-state representation of system components. The objective of this research is to demonstrate the process of dynamic flowgraph modeling of a nuclear-based hydrogen production plant with the copper-chlorine (Cu-Cl) cycle. Modeling of the thermochemical process of the Cu-Cl cycle in conjunction with a networked control system proposed for monitoring and control of the process is provided. This forms the basis for future component selection. (author)

  8. Real-time electron dynamics simulation of two-electron transfer reactions induced by nuclear motion

    Science.gov (United States)

    Suzuki, Yasumitsu; Yamashita, Koichi

    2012-04-01

    Real-time electron dynamics of two-electron transfer reactions induced by nuclear motion is calculated by three methods: the numerically exact propagation method, the time-dependent Hartree (TDH) method and the Ehrenfest method. We find that, as long as the nuclei move as localized wave packets, the TDH and Ehrenfest methods can reproduce the exact electron dynamics of a simple charge transfer reaction model containing two electrons qualitatively well, even when nonadiabatic transitions between adiabatic states occur. In particular, both methods can reproduce the cases where a complete two-electron transfer reaction occurs and those where it does not occur.

  9. Monitoring Nonadiabatic Electron-Nuclear Dynamics in Molecules by Attosecond Streaking of Photoelectrons.

    Science.gov (United States)

    Kowalewski, Markus; Bennett, Kochise; Rouxel, Jérémy R; Mukamel, Shaul

    2016-07-22

    Streaking of photoelectrons has long been used for the temporal characterization of attosecond extreme ultraviolet pulses. When the time-resolved photoelectrons originate from a coherent superposition of electronic states, they carry additional phase information, which can be retrieved by the streaking technique. In this contribution we extend the streaking formalism to include coupled electron and nuclear dynamics in molecules as well as initial coherences. We demonstrate how streaked photoelectrons offer a novel tool for monitoring nonadiabatic dynamics as it occurs in the vicinity of conical intersections and avoided crossings. Streaking can provide high time resolution direct signatures of electronic coherences, which affect many primary photochemical and biological events.

  10. Temperature dependence of cross-effect dynamic nuclear polarization in rotating solids

    DEFF Research Database (Denmark)

    Geiger, Michel-Andreas; Orwick-Rydmark, Marcella; Märker, Katharina

    2016-01-01

    Dynamic nuclear polarization exploits electron spin polarization to boost signal-to-noise in magic-angle-spinning (MAS) NMR, creating new opportunities in materials science, structural biology, and metabolomics studies. Since protein NMR spectra recorded under DNP conditions can show improved...... the importance of protons in a sphere of 4-6 Å around the nitroxyl group, presumably for polarization pickup from electron spins....

  11. Development of a dynamical systems model of plant programmatic performance on nuclear power plant safety risk

    Energy Technology Data Exchange (ETDEWEB)

    Hess, Stephen M. [Sensortex, Inc., 515 Schoolhouse Road, Kennett Square, PA 19348 (United States)]. E-mail: smhess@sensortex.com; Albano, Alfonso M. [Department of Physics, Bryn Mawr College, Bryn Mawr, PA 19010 (United States); Gaertner, John P. [Electric Power Research Institute, 1300 Harris Boulevard, Charlotte, NC 28262 (United States)

    2005-10-01

    Application of probabilistic risk assessment (PRA) techniques to model nuclear power plant accident sequences has provided a significant contribution to understanding the potential initiating events, equipment failures and operator errors that can lead to core damage accidents. Application of the lessons learned from these analyses has resulted in significant improvements in plant operation and safety. However, this approach has not been nearly as successful in addressing the impact of plant processes and management effectiveness on the risks of plant operation. The research described in this paper presents an alternative approach to addressing this issue. In this paper we propose a dynamical systems model that describes the interaction of important plant processes on nuclear safety risk. We discuss development of the mathematical model including the identification and interpretation of significant inter-process interactions. Next, we review the techniques applicable to analysis of nonlinear dynamical systems that are utilized in the characterization of the model. This is followed by a preliminary analysis of the model that demonstrates that its dynamical evolution displays features that have been observed at commercially operating plants. From this analysis, several significant insights are presented with respect to the effective control of nuclear safety risk. As an important example, analysis of the model dynamics indicates that significant benefits in effectively managing risk are obtained by integrating the plant operation and work management processes such that decisions are made utilizing a multidisciplinary and collaborative approach. We note that although the model was developed specifically to be applicable to nuclear power plants, many of the insights and conclusions obtained are likely applicable to other process industries.

  12. Electron dynamics upon ionization: Control of the timescale through chemical substitution and effect of nuclear motion

    Energy Technology Data Exchange (ETDEWEB)

    Vacher, Morgane; Bearpark, Michael J.; Robb, Michael A. [Department of Chemistry, Imperial College London, London SW7 2AZ (United Kingdom); Mendive-Tapia, David [Laboratoire CEISAM - UMR CNR 6230, Université de Nantes, 2 Rue de la Houssinière, BP 92208, 44322 Nantes Cedex 3 (France)

    2015-03-07

    Photoionization can generate a non-stationary electronic state, which leads to coupled electron-nuclear dynamics in molecules. In this article, we choose benzene cation as a prototype because vertical ionization of the neutral species leads to a Jahn-Teller degeneracy between ground and first excited states of the cation. Starting with equal populations of ground and first excited states, there is no electron dynamics in this case. However, if we add methyl substituents that break symmetry but do not radically alter the electronic structure, we see charge migration: oscillations in the spin density that we can correlate with particular localized electronic structures, with a period depending on the gap between the states initially populated. We have also investigated the effect of nuclear motion on electron dynamics using a complete active space self-consistent field (CASSCF) implementation of the Ehrenfest method, most previous theoretical studies of electron dynamics having been carried out with fixed nuclei. In toluene cation for instance, simulations where the nuclei are allowed to move show significant differences in the electron dynamics after 3 fs, compared to simulations with fixed nuclei.

  13. a Bidirectional Reflectance Model for Non-Random Canopies.

    Science.gov (United States)

    Welles, Jonathan Mark

    The general array model (GAR) is extended to calculate bidirectional reflectance (reflectance as a function of angle of view and angle of illumination) of a plant stand. The new model (BIGAR) defines the plant canopy as one or more foliage-containing ellipsoids arranged in any desired pattern. Foliage is assumed randomly distributed within each ellipsoid, with a specified distribution of inclination angles and random azimuthal orientation distribution. A method of specifying sub-ellipsoids that contain foliage of varying properties is discussed. Foliage is assumed to scatter radiation in a Lambertian fashion. The soil bidirectional reflectance is modelled separately as a boundary condition. The reflectance of any given grid point within the plant stand is calculated from the incident radiation (direct beam, diffuse sky, and diffuse scattered from the soil and foliage) and a view weighting factor that is based upon how much of the view is occupied by that particular grid point. Integrating this over a large number of grid locations provides a prediction of the bidirectional reflectance. Model predictions are compared with measurements in corn and soybean canopies at three stages of growth. The model does quite well in predicting the general shape and dynamics of the measured bidirectional reflectance factors, and rms errors are typically 10% to 15% (relative) of the integrated reflectance value. The effect of rows is evident in both the measurements and the model in the early part of the growing season. The presence of tassles in the corn may be the cause of unpredicted row effects later in the season. Predicted nadir reflectances are accurate for soybean, but are low for full cover corn. The presence of specular reflection causes the model to slightly underpredict reflectances looking toward the sun at large solar zenith angles.

  14. Dynamic nuclear spin polarization in the resonant laser excitation of an InGaAs quantum dot.

    Science.gov (United States)

    Högele, A; Kroner, M; Latta, C; Claassen, M; Carusotto, I; Bulutay, C; Imamoglu, A

    2012-05-11

    Resonant optical excitation of lowest-energy excitonic transitions in self-assembled quantum dots leads to nuclear spin polarization that is qualitatively different from the well-known optical orientation phenomena. By carrying out a comprehensive set of experiments, we demonstrate that nuclear spin polarization manifests itself in quantum dots subjected to finite external magnetic field as locking of the higher energy Zeeman transition to the driving laser field, as well as the avoidance of the resonance condition for the lower energy Zeeman branch. We interpret our findings on the basis of dynamic nuclear spin polarization originating from noncollinear hyperfine interaction and find excellent agreement between experiment and theory. Our results provide evidence for the significance of noncollinear hyperfine processes not only for nuclear spin diffusion and decay, but also for buildup dynamics of nuclear spin polarization in a coupled electron-nuclear spin system.

  15. Pedestrians rotation measurement in bidirectional streams

    CERN Document Server

    Feliciani, Claudio

    2016-01-01

    This study presents an experimental measurement of pedestrians' body rotation in bidirectional streams. A mock-up corridor monitored using a camera placed on azimuthal position is used to study pedestrians' behavior in unidirectional and bidirectional flows. Additionally, a commercial tablet is fixed on the chest of sample pedestrians to examine their body rotation (or yawing) which cannot be obtained using position tracking alone. Angular velocity is recorded and simultaneously stored in a central location using a wireless network, thus allowing the analysis of body movements with a high sampling rate and a limited delay. To investigate the influence of major/minor flow proportion (flow-ratio) on bidirectional streams two different situations were tested: the balanced configuration (with equal flows in both directions) and an unbalanced configuration (with different major and minor flow). Results clearly show that unidirectional flow is more stable compared to the bidirectional case, requiring less time to c...

  16. Alpha-beta bidirectional associative memories

    OpenAIRE

    María Elena Acevedo Mosqueda; Cornelio Yáñez Márquez

    2006-01-01

    Most models of Bidirectional associative memories intend to achieve that all trained pattern correspond to stable states; however, this has not been possible. Also, none of the former models has been able to recall all the trained patterns. In this work we introduce a new model of bidirectional associative memory which is not iterative and has no stability problems. It is based on the Alpha-Beta associative memories. This model allows perfect recall of all trained patterns, with no ambiguity ...

  17. Nonadiabatic nuclear dynamics of the ammonia cation studied by surface hopping classical trajectory calculations

    Science.gov (United States)

    Belyaev, Andrey K.; Domcke, Wolfgang; Lasser, Caroline; Trigila, Giulio

    2015-03-01

    The Landau-Zener (LZ) type classical-trajectory surface-hopping algorithm is applied to the nonadiabatic nuclear dynamics of the ammonia cation after photoionization of the ground-state neutral molecule to the excited states of the cation. The algorithm employs a recently proposed formula for nonadiabatic LZ transition probabilities derived from the adiabatic potential energy surfaces. The evolution of the populations of the ground state and the two lowest excited adiabatic states is calculated up to 200 fs. The results agree well with quantum simulations available for the first 100 fs based on the same potential energy surfaces. Three different time scales are detected for the nuclear dynamics: Ultrafast Jahn-Teller dynamics between the excited states on a 5 fs time scale; fast transitions between the excited state and the ground state within a time scale of 20 fs; and relatively slow partial conversion of a first-excited-state population to the ground state within a time scale of 100 fs. Beyond 100 fs, the adiabatic electronic populations are nearly constant due to a dynamic equilibrium between the three states. The ultrafast nonradiative decay of the excited-state populations provides a qualitative explanation of the experimental evidence that the ammonia cation is nonfluorescent.

  18. Dynamic Nuclear Polarization and Relaxation of H and D Atoms in Solid Mixtures of Hydrogen Isotopes

    Science.gov (United States)

    Sheludiakov, S.; Ahokas, J.; Järvinen, J.; Vainio, O.; Lehtonen, L.; Vasiliev, S.; Lee, D. M.; Khmelenko, V. V.

    2016-12-01

    We report on a study of dynamic nuclear polarization and electron and nuclear spin relaxation of atomic hydrogen and deuterium in solid molecular matrices of H2, D2 , and HD mixtures. The electron and nuclear spin relaxation times (T_{1e} and T_{1N} ) were measured within the temperature range 0.15-2.5 K in a magnetic field of 4.6 T, conditions which ensure a high polarization of electron spins. We found that T_{1e} is nearly temperature independent in this temperature range, while T_{1N} decreased by two orders of magnitude upon raising temperature. Such strong temperature dependence is typical for the nuclear Orbach mechanism of relaxation via the electron spins. We found that the nuclear spins of H atoms in solid D2 and D2{:}HD can be efficiently polarized by the Overhauser effect. Pumping the forbidden transitions of H atoms also leads to DNP, with the efficiency strongly dependent on the concentration of D atoms. This behavior indicates the cross effect mechanism of the DNP and nuclear relaxation, which turns out to be well resolved in the conditions of our experiments. Efficient DNP of H atoms was also observed when pumping the middle D line located in the center of the ESR spectrum. This phenomenon can be explained in terms of clusters or pairs of H atoms with a strong exchange interaction. These clusters have partially allowed transitions in the center of the ESR spectrum, and DNP may be created via the resolved cross effect.

  19. Dynamics of light, intermediate, heavy and superheavy nuclear systems formed in heavy-ion collisions

    Indian Academy of Sciences (India)

    Manoj K Sharma; Gurvinder Kaur

    2014-05-01

    The dynamical description of light, intermediate, heavy and superheavy nuclei formed in heavy-ion collisions is worked out using the dynamical cluster decay model (DCM), with reference to various effects such as deformation and orientation, temperature, angular momentum etc. Based on the quantum mechanical fragmentation theory (QMFT), DCM has been applied to understand the decay mechanism of a large number of nuclei formed in low-energy heavy-ion reactions. Various features related to the dynamics of competing decay modes of nuclear systems are explored by addressing the experimental data of a number of reactions in light, intermediate, heavy and superheavy mass regions. The DCM, being a non-statistical description for the decay of a compound nucleus, treats light particles (LPs) or equivalently evaporation residues (ERs), intermediate mass fragments (IMFs) and fission fragments on equal footing and hence, provides an alternative to the available statistical model approaches to address fusion–fission and related phenomena.

  20. The dynamic polarization potential and dynamical non-locality in nuclear potentials: Deuteron-nucleus potential

    CERN Document Server

    Mackintosh, R S

    2016-01-01

    The consequences for direct reactions of the dynamical non-locality generated by the excitation of the target and projectile are much less studied than the effects of non-locality arising from exchange processes. Here we are concerned with the dynamical non-locality due to projectile excitation in deuteron induced reactions. The consequences of this non-locality can be studied by the comparison of deuteron induced direct reactions calculated with alternative representations of the elastic channel wave functions: (i) the elastic channel wave functions from coupled channel (CC) calculations involving specific reaction processes, and, (ii) elastic channel wave functions calculated from local potentials that exactly reproduce the elastic scattering $S$-matrix from the same CC calculations. In this work we produce the local equivalent deuteron potentials required for the study of direct reactions involving deuterons. These will enable the study of the effects of dynamical non-locality following a method previously...

  1. Nuclear dynamics during germination, conidiation, and hyphal fusion of Fusarium oxysporum.

    Science.gov (United States)

    Ruiz-Roldán, M Carmen; Köhli, Michael; Roncero, M Isabel G; Philippsen, Peter; Di Pietro, Antonio; Espeso, Eduardo A

    2010-08-01

    In many fungal pathogens, infection is initiated by conidial germination. Subsequent stages involve germ tube elongation, conidiation, and vegetative hyphal fusion (anastomosis). Here, we used live-cell fluorescence to study the dynamics of green fluorescent protein (GFP)- and cherry fluorescent protein (ChFP)-labeled nuclei in the plant pathogen Fusarium oxysporum. Hyphae of F. oxysporum have uninucleated cells and exhibit an acropetal nuclear pedigree, where only the nucleus in the apical compartment is mitotically active. In contrast, conidiation follows a basopetal pattern, whereby mononucleated microconidia are generated by repeated mitotic cycles of the subapical nucleus in the phialide, followed by septation and cell abscission. Vegetative hyphal fusion is preceded by directed growth of the fusion hypha toward the receptor hypha and followed by a series of postfusion nuclear events, including mitosis of the apical nucleus of the fusion hypha, migration of a daughter nucleus into the receptor hypha, and degradation of the resident nucleus. These previously unreported patterns of nuclear dynamics in F. oxysporum could be intimately related to its pathogenic lifestyle.

  2. A redox-sensitive yellow fluorescent protein sensor for monitoring nuclear glutathione redox dynamics.

    Science.gov (United States)

    Banach-Latapy, Agata; Dardalhon, Michèle; Huang, Meng-Er

    2015-01-01

    Intracellular redox homeostasis is crucial for many cellular functions, but accurate measurements of cellular compartment-specific redox states remain technically challenging. Genetically encoded biosensors, including the glutathione-specific redox-sensitive yellow fluorescent protein (rxYFP), provide an alternative approach to overcome the limitations of conventional glutathione/glutathione disulfide (GSH/GSSG) redox measurements. In this chapter we describe methods to measure the nuclear rxYFP redox state in human cells by a redox Western blot technique. A nucleus-targeted rxYFP sensor can be used to sense nuclear steady-state and dynamic redox changes in response to oxidative stress. Complementary to existing redox sensors and conventional redox measurements, nucleus-targeted rxYFP sensors provide a novel tool for examining nuclear redox homeostasis in mammalian cells, permitting high-resolution readout of steady glutathione state and dynamics of redox changes. The technique described may be used with minimal variations to study the effects of stress conditions which lead to glutathione redox changes.

  3. Bi-directional thruster development and test report

    Science.gov (United States)

    Jacot, A. D.; Bushnell, G. S.; Anderson, T. M.

    1990-01-01

    The design, calibration and testing of a cold gas, bi-directional throttlable thruster are discussed. The thruster consists of an electro-pneumatic servovalve exhausting through opposite nozzles with a high gain pressure feedback loop to optimize performance. The thruster force was measured to determine hysteresis and linearity. Integral gain was used to maximize performance for linearity, hysteresis, and minimum thrust requirements. Proportional gain provided high dynamic response (bandwidth and phase lag). Thruster performance is very important since the thrusters are intended to be used for active control.

  4. Symmetric reconfigurable capacity assignment in a bidirectional DWDM access network.

    Science.gov (United States)

    Ortega, Beatriz; Mora, José; Puerto, Gustavo; Capmany, José

    2007-12-10

    This paper presents a novel architecture for DWDM bidirectional access networks providing symmetric dynamic capacity allocation for both downlink and uplink signals. A foldback arrayed waveguide grating incorporating an optical switch enables the experimental demonstration of flexible assignment of multiservice capacity. Different analog and digital services, such as CATV, 10 GHz-tone, 155Mb/s PRBS and UMTS signals have been transmitted in order to successfully test the system performance under different scenarios of total capacity distribution from the Central Station to different Base Stations with two reconfigurable extra channels for each down and upstream direction.

  5. Hybrid Parallel Bidirectional Sieve based on SMP Cluster

    CERN Document Server

    Liao, Gang; Liu, Lei

    2012-01-01

    In this article, hybrid parallel bidirectional sieve method is implemented by SMP Cluster, the individual computational units joined together by the communication network, are usually shared-memory systems with one or more multicore processor. To high-efficiency optimization, we propose average divide data into nodes, generating double-ended queues (deque) for sieve method that are able to exploit dual-cores simultaneously start sifting out primes from the head and tail.And each node create a FIFO queue as dynamic data buffer to ache temporary data from another nodes send to. The approach obtains huge speedup and efficiency on SMP Cluster.

  6. THz-waves channeling in a monolithic saddle-coil for Dynamic Nuclear Polarization enhanced NMR.

    Science.gov (United States)

    Macor, A; de Rijk, E; Annino, G; Alberti, S; Ansermet, J-Ph

    2011-10-01

    A saddle coil manufactured by electric discharge machining (EDM) from a solid piece of copper has recently been realized at EPFL for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance experiments (DNP-NMR) at 9.4 T. The corresponding electromagnetic behavior of radio-frequency (400 MHz) and THz (263 GHz) waves were studied by numerical simulation in various measurement configurations. Moreover, we present an experimental method by which the results of the THz-wave numerical modeling are validated. On the basis of the good agreement between numerical and experimental results, we conducted by numerical simulation a systematic analysis on the influence of the coil geometry and of the sample properties on the THz-wave field, which is crucial in view of the optimization of DNP-NMR in solids.

  7. The magnetic field dependence of cross-effect dynamic nuclear polarization under magic angle spinning

    Energy Technology Data Exchange (ETDEWEB)

    Mance, Deni; Baldus, Marc, E-mail: m.baldus@uu.nl [NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, 3584 CH Utrecht (Netherlands); Gast, Peter; Huber, Martina [Department of Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, PO Box 9504, 2300 RA Leiden (Netherlands); Ivanov, Konstantin L., E-mail: ivanov@tomo.nsc.ru [International Tomography Center, Siberian Branch of the Russian Academy of Science, Institutskaya 3a, Novosibirsk 630090, Russia and Novosibirsk State University, Pirogova 2, Novosibirsk 63009 (Russian Federation)

    2015-06-21

    We develop a theoretical description of Dynamic Nuclear Polarization (DNP) in solids under Magic Angle Spinning (MAS) to describe the magnetic field dependence of the DNP effect. The treatment is based on an efficient scheme for numerical solution of the Liouville-von Neumann equation, which explicitly takes into account the variation of magnetic interactions during the sample spinning. The dependence of the cross-effect MAS-DNP on various parameters, such as the hyperfine interaction, electron-electron dipolar interaction, microwave field strength, and electron spin relaxation rates, is analyzed. Electron spin relaxation rates are determined by electron paramagnetic resonance measurements, and calculations are compared to experimental data. Our results suggest that the observed nuclear magnetic resonance signal enhancements provided by MAS-DNP can be explained by discriminating between “bulk” and “core” nuclei and by taking into account the slow DNP build-up rate for the bulk nuclei.

  8. CRISPR-Cas9 nuclear dynamics and target recognition in living cells.

    Science.gov (United States)

    Ma, Hanhui; Tu, Li-Chun; Naseri, Ardalan; Huisman, Maximiliaan; Zhang, Shaojie; Grunwald, David; Pederson, Thoru

    2016-08-29

    The bacterial CRISPR-Cas9 system has been repurposed for genome engineering, transcription modulation, and chromosome imaging in eukaryotic cells. However, the nuclear dynamics of clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (Cas9) guide RNAs and target interrogation are not well defined in living cells. Here, we deployed a dual-color CRISPR system to directly measure the stability of both Cas9 and guide RNA. We found that Cas9 is essential for guide RNA stability and that the nuclear Cas9-guide RNA complex levels limit the targeting efficiency. Fluorescence recovery after photobleaching measurements revealed that single mismatches in the guide RNA seed sequence reduce the target residence time from >3 h to as low as CRISPR discriminates between genuine versus mismatched targets for genome editing via radical alterations in residence time.

  9. Chiral dynamics of baryon resonances and hadrons in a nuclear medium

    Indian Academy of Sciences (India)

    E Oset; D Cabrera; V K Magas; L Roca; S Sarkar; M J Vicente Vacas; A Ramos

    2006-04-01

    In these lectures I make an introduction to chiral unitary theory applied to the meson-baryon interaction and show how several well-known resonances are dynamically generated, and others are predicted. Two very recent experiments are analyzed, one of them showing the existence of two (1405) states and the other one providing support for the (1520) resonance as a quasi-bound state of $\\sum (1385) $. The use of chiral Lagrangians to account for the hadronic interaction at the elementary level introduces a new approach to deal with the modification of meson and baryon properties in a nuclear medium. Examples of it for $\\bar{K}$, and modification in the nuclear medium are presented.

  10. p -shell carrier assisted dynamic nuclear spin polarization in single quantum dots at zero external magnetic field

    Science.gov (United States)

    Fong, C. F.; Ota, Y.; Harbord, E.; Iwamoto, S.; Arakawa, Y.

    2016-03-01

    Repeated injection of spin-polarized carriers in a quantum dot (QD) leads to the polarization of nuclear spins, a process known as dynamic nuclear spin polarization (DNP). Here, we report the observation of p-shell carrier assisted DNP in single QDs at zero external magnetic field. The nuclear field—measured by using the Overhauser shift of the singly charged exciton state of the QDs—continues to increase, even after the carrier population in the s-shell saturates. This is also accompanied by an abrupt increase in nuclear spin buildup time as p-shell emission overtakes that of the s shell. We attribute the observation to p-shell electrons strongly altering the nuclear spin dynamics in the QD, supported by numerical simulation results based on a rate equation model of coupling between electron and nuclear spin system. Dynamic nuclear spin polarization with p-shell carriers could open up avenues for further control to increase the degree of nuclear spin polarization in QDs.

  11. Nonadiabatic nuclear dynamics of the ammonia cation studied by surface hopping classical trajectory calculations

    CERN Document Server

    Belyaev, Andrey K; Lasser, Caroline; Trigila, Giulio

    2014-01-01

    The Landau--Zener (LZ) type classical-trajectory surface-hopping algorithm is applied to the nonadiabatic nuclear dynamics of the ammonia cation after photoionization of the ground-state neutral molecule to the excited states of the cation. The algorithm employs the recently proposed formula for nonadiabatic LZ transition probabilities derived from the adiabatic potential energy surfaces. The evolution of the populations of the ground state and the two lowest excited adiabatic states is calculated up to 200 fs. The results agree well with quantum simulations available for the first 100 fs based on the same potential energy surfaces. Four different time scales are detected for the nuclear dynamics: Ultrafast Jahn--Teller dynamics between the excited states on a 5 fs time scale; fast transitions between the excited state and the ground state within a time scale of 20 fs; relatively slow partial conversion of a first-excited-state population to the ground state within a time scale of 100 fs; and nearly constant ...

  12. FOREWORD: International Summer School for Advanced Studies 'Dynamics of open nuclear systems' (PREDEAL12)

    Science.gov (United States)

    Delion, D. S.; Zamfir, N. V.; Raduta, A. R.; Gulminelli, F.

    2013-02-01

    This proceedings volume contains the invited lectures and contributions presented at the International Summer School on Nuclear Physics held at Trei Brazi, a summer resort of the Bioterra University, near the city of Predeal, Romania, on 9-20 July 2012. The long tradition of International Summer Schools on Nuclear Physics in Romania dates as far back as 1964, with the event being scheduled every two years. During this period of almost 50 years, many outstanding nuclear scientists have lectured on various topics related to nuclear physics and particle physics. This year we celebrate the 80th birthday of Aureliu Sandulescu, one of the founders of the Romanian school of theoretical nuclear physics. He was Serban Titeica's PhD student, one of Werner Heisenberg's PhD students, and he organized the first edition of this event. Aureliu Sandulescu's major contributions to the field of theoretical nuclear physics are related in particular to the prediction of cluster radioactivity, the physics of open quantum systems and the innovative technique of detecting superheavy nuclei using the double magic projectile 48Ca (Calcium), nowadays a widely used method at the JINR—Dubna and GSI—Darmstadt laboratories. The title of the event, 'Dynamics of Open Nuclear Systems', is in recognition of Aureliu Sandulescu's great personality. The lectures were attended by Romanian and foreign Master and PhD students and young researchers in nuclear physics. About 25 reputable professors and researchers in nuclear physics delivered lectures during this period. According to a well-established tradition, an interval of two hours was allotted for each lecture (including discussions). Therefore we kept a balance between the school and conference format. Two lectures were held during the morning and afternoon sessions. After lecture sessions, three or four oral contributions were given by young scientists. This was a good opportunity for them to present the results of their research in front of

  13. Autophagy contributes to regulation of nuclear dynamics during vegetative growth and hyphal fusion in Fusarium oxysporum.

    Science.gov (United States)

    Corral-Ramos, Cristina; Roca, M Gabriela; Di Pietro, Antonio; Roncero, M Isabel G; Ruiz-Roldán, Carmen

    2015-01-01

    In the fungal pathogen Fusarium oxysporum, vegetative hyphal fusion triggers nuclear mitotic division in the invading hypha followed by migration of a nucleus into the receptor hypha and degradation of the resident nucleus. Here we examined the role of autophagy in fusion-induced nuclear degradation. A search of the F. oxysporum genome database for autophagy pathway components identified putative orthologs of 16 core autophagy-related (ATG) genes in yeast, including the ubiquitin-like protein Atg8, which is required for the formation of autophagosomal membranes. F. oxysporum Foatg8Δ mutants were generated in a strain harboring H1-cherry fluorescent protein (ChFP)-labeled nuclei to facilitate analysis of nuclear dynamics. The Foatg8Δ mutants did not show MDC-positive staining in contrast to the wild type and the FoATG8-complemented (cFoATG8) strain, suggesting that FoAtg8 is required for autophagy in F. oxysporum. The Foatg8Δ strains displayed reduced rates of hyphal growth, conidiation, and fusion, and were significantly attenuated in virulence on tomato plants and in the nonvertebrate animal host Galleria mellonella. In contrast to wild-type hyphae, which are almost exclusively composed of uninucleated hyphal compartments, the hyphae of the Foatg8Δ mutants contained a significant fraction of hyphal compartments with 2 or more nuclei. The increase in the number of nuclei per hyphal compartment was particularly evident after hyphal fusion events. Time-lapse microscopy analyses revealed abnormal mitotic patterns during vegetative growth in the Foatg8Δ mutants. Our results suggest that autophagy mediates nuclear degradation after hyphal fusion and has a general function in the control of nuclear distribution in F. oxysporum.

  14. Dynamic nuclear polarization NMR spectroscopy allows high-throughput characterization of microporous organic polymers.

    Science.gov (United States)

    Blanc, Frédéric; Chong, Samantha Y; McDonald, Tom O; Adams, Dave J; Pawsey, Shane; Caporini, Marc A; Cooper, Andrew I

    2013-10-16

    Dynamic nuclear polarization (DNP) solid-state NMR was used to obtain natural abundance (13)C and (15)N CP MAS NMR spectra of microporous organic polymers with excellent signal-to-noise ratio, allowing for unprecedented details in the molecular structure to be determined for these complex polymer networks. Sensitivity enhancements larger than 10 were obtained with bis-nitroxide radical at 14.1 T and low temperature (∼105 K). This DNP MAS NMR approach allows efficient, high-throughput characterization of libraries of porous polymers prepared by combinatorial chemistry methods.

  15. Instrumentation for solid-state dynamic nuclear polarization with magic angle spinning NMR

    Science.gov (United States)

    Rosay, Melanie; Blank, Monica; Engelke, Frank

    2016-03-01

    Advances in dynamic nuclear polarization (DNP) instrumentation and methodology have been key factors in the recent growth of solid-state DNP NMR applications. We review the current state of the art of solid-state DNP NMR instrumentation primarily based on available commercial platforms. We start with a general system overview, including options for microwave sources and DNP NMR probes, and then focus on specific developments for DNP at 100 K with magic angle spinning (MAS). Gyrotron microwave sources, passive components to transmit microwaves, the DNP MAS probe, a cooling device for low-temperature MAS, and sample preparation procedures including radicals for DNP are considered.

  16. Comparative analyses of bidirectional promoters in vertebrates

    Directory of Open Access Journals (Sweden)

    Taylor James

    2008-05-01

    Full Text Available Abstract Background Orthologous genes with deep phylogenetic histories are likely to retain similar regulatory features. In this report we utilize orthology assignments for pairs of genes co-regulated by bidirectional promoters to map the ancestral history of the promoter regions. Results Our mapping of bidirectional promoters from humans to fish shows that many such promoters emerged after the divergence of chickens and fish. Furthermore, annotations of promoters in deep phylogenies enable detection of missing data or assembly problems present in higher vertebrates. The functional importance of bidirectional promoters is indicated by selective pressure to maintain the arrangement of genes regulated by the promoter over long evolutionary time spans. Characteristics unique to bidirectional promoters are further elucidated using a technique for unsupervised classification, known as ESPERR. Conclusion Results of these analyses will aid in our understanding of the evolution of bidirectional promoters, including whether the regulation of two genes evolved as a consequence of their proximity or if function dictated their co-regulation.

  17. Dynamics of water-alcohol mixtures: Insights from nuclear magnetic resonance, broadband dielectric spectroscopy, and triplet solvation dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Sauer, D.; Schuster, B.; Rosenstihl, M.; Schneider, S.; Blochowicz, T.; Stühn, B.; Vogel, M. [Institut für Festkörperphysik, Technische Universität Darmstadt, Hochschulstraße 6, 64289 Darmstadt (Germany); Talluto, V.; Walther, T. [Institut für Angewandte Physik, Technische Universität Darmstadt, Schlossgartenstraße 7, 64289 Darmstadt (Germany)

    2014-03-21

    We combine {sup 2}H nuclear magnetic resonance (NMR), broadband dielectric spectroscopy (BDS), and triplet solvation dynamics (TSD) to investigate molecular dynamics in glass-forming mixtures of water and propylene glycol in very broad time and temperature ranges. All methods yield consistent results for the α process of the studied mixtures, which hardly depends on the composition and shows Vogel-Fulcher temperature dependence as well as Cole-Davidson spectral shape. The good agreement between BDS and TDS data reveals that preferential solvation of dye molecules in microheterogeneous mixtures does not play an important role. Below the glass transition temperature T{sub g}, NMR and BDS studies reveal that the β process of the mixtures shows correlation times, which depend on the water concentration, but exhibit a common temperature dependence, obeying an Arrhenius law with an activation energy of E{sub a} = 0.54  eV, as previously reported for mixtures of water with various molecular species. Detailed comparison of NMR and BDS correlation functions for the β process unravels that the former decay faster and more stretched than the latter. Moreover, the present NMR data imply that propylene glycol participates in the β process and, hence, it is not a pure water process, and that the mechanism for molecular dynamics underlying the β process differs in mixtures of water with small and large molecules.

  18. Theoretical approaches to control spin dynamics in solid-state nuclear magnetic resonance

    Indian Academy of Sciences (India)

    Eugene Stephane Mananga

    2015-12-01

    This article reviews theoretical approaches for controlling spin dynamics in solid-state nuclear magnetic resonance. We present fundamental theories in the history of NMR, namely, the average Hamiltonian and Floquet theories. We also discuss emerging theories such as the Fer and Floquet-Magnus expansions. These theories allow one to solve the time-dependent Schrodinger equation, which is still the central problem in spin dynamics of solid-state NMR. Examples from the literature that highlight several applications of these theories are presented, and particular attention is paid to numerical integrators and propagator operators. The problem of time propagation calculated with Chebychev expansion and the future development of numerical directions with the Cayley transformation are considered. The bibliography includes 190 references.

  19. Time-Domain Nuclear Magnetic Resonance Investigation of Water Dynamics in Different Ginger Cultivars.

    Science.gov (United States)

    Huang, Chongyang; Zhou, Qi; Gao, Shan; Bao, Qingjia; Chen, Fang; Liu, Chaoyang

    2016-01-20

    Different ginger cultivars may contain different nutritional and medicinal values. In this study, a time-domain nuclear magnetic resonance method was employed to study water dynamics in different ginger cultivars. Significant differences in transverse relaxation time T2 values assigned to the distribution of water in different parts of the plant were observed between Henan ginger and four other ginger cultivars. Ion concentration and metabolic analysis showed similar differences in Mn ion concentrations and organic solutes among the different ginger cultivars, respectively. On the basis of Pearson's correlation analysis, many organic solutes and 6-gingerol, the main active substance of ginger, exhibited significant correlations with water distribution as determined by NMR T2 relaxation, suggesting that the organic solute differences may impact water distribution. Our work demonstrates that low-field NMR relaxometry provides useful information about water dynamics in different ginger cultivars as affected by the presence of different organic solutes.

  20. The fragile-to-strong dynamic crossover transition in confined water: nuclear magnetic resonance results.

    Science.gov (United States)

    Mallamace, F; Broccio, M; Corsaro, C; Faraone, A; Wanderlingh, U; Liu, L; Mou, C-Y; Chen, S H

    2006-04-28

    By means of a nuclear magnetic resonance experiment, we give evidence of the existence of a fragile-to-strong dynamic crossover transition (FST) in confined water at a temperature T(L)=223+/-2 K. We have studied the dynamics of water contained in 1D cylindrical nanoporous matrices (MCM-41-S) in the temperature range 190-280 K, where experiments on bulk water were so far hampered by crystallization. The FST is clearly inferred from the T dependence of the inverse of the self-diffusion coefficient of water (1D) as a crossover point from a non-Arrhenius to an Arrhenius behavior. The combination of the measured self-diffusion coefficient D and the average translational relaxation time tau(T), as measured by neutron scattering, shows the predicted breakdown of Stokes-Einstein relation in deeply supercooled water.

  1. Dynamics of ferrocene in molecular sieves probed by Mossbauer spectroscopy and nuclear resonant scattering

    Energy Technology Data Exchange (ETDEWEB)

    Asthalter, T [Institut fuer Physikalische Chemie, Universitat Stuttgart, D-70569 Stuttgart (Germany); Sergueev, I [European Synchrotron Radiation Facility, F-38043 Grenoble (France); Buerck, U van; Wagner, F E [Experimentalphysik E13, Technische Universitaet Muenchen, D-85747 Garching (Germany); Haerter, P [Anorganische Chemie, Technische Universitaet Muenchen, D-85747 Garching (Germany); Kornatowski, J [Max-Planck-Institut fuer Kohlenforschung, D-45470 Muelheim (Germany); Klingelhoefer, S; Behrens, P, E-mail: t.asthalter@ipc.uni-stuttgart.d [Anorganische Chemie, Leibniz-Universitaet Hannover, D-30167 Hannover (Germany)

    2010-03-01

    A detailed study on the slow dynamics of ferrocene in the unidimensional channels of the molecular sieves SSZ-24 and AlPO{sub 4}-5 has been carried out, using Moessbauer spectroscopy (MS), nuclear forward scattering (NFS) and synchrotron radiation-based perturbed angular correlations (SRPAC). In both host systems, anisotropic rotational dynamics is observed above 100 K. For SSZ-24, this anisotropy persists even above the bulk melting temperature of ferrocene. Various theoretical models are exploited for the study of anisotropic discrete jump rotations for the first time. The experimental data can be described fairly well by a jump model that involves reorientations of the molecular axis on a cone mantle with an opening angle dependant on temperature.

  2. NASA solar dynamic ground test demonstration (GTD) program and its application to space nuclear power

    Science.gov (United States)

    Harper, William B.; Shaltens, Richard K.

    1993-01-01

    Closed Brayton cycle power conversion systems are readily adaptable to any heat source contemplated for space application. The inert gas working fluid can be used directly in gas-cooled reactors and coupled to a variety of heat sources (reactor, isotope or solar) by a heat exchanger. This point is demonstrated by the incorporation in the NASA 2 kWe Solar Dynamic (SD) Space Power Ground Test Demonstration (GTD) Program of the turboalternator-compressor and recuperator from the Brayton Isotope Power System (BIPS) program. This paper will review the goals and status of the SD GTD Program, initiated in April 1992. The performance of the BIPS isotope-heated system will be compared to the solar-heated GTD system incorporating the BIPS components and the applicability of the GTD test bed to dynamics space nuclear power R&D will be discussed.

  3. On the balance energy and nuclear dynamics in peripheral heavy-ion collisions

    CERN Document Server

    Chugh, Rajiv

    2010-01-01

    We present here the system size dependence of balance energy for semi-central and peripheral collisions using quantum molecular dynamics model. For this study, the reactions of $Ne^{20}+Ne^{20}$, $Ca^{40}+Ca^{40}$, $Ni^{58}+Ni^{58}$, $Nb^{93}+Nb^{93}$, $Xe^{131}+Xe^{131}$ and $Au^{197}+Au^{197}$ are simulated at different incident energies and impact parameters. A hard equation of state along with nucleon-nucleon cross-sections between 40 - 55 mb explains the data nicely. Interestingly, balance energy follows a power law $\\propto{A^{\\tau}}$ for the mass dependence at all colliding geometries. The power factor $\\tau$ is close to -1/3 in central collisions whereas it is -2/3 for peripheral collisions suggesting stronger system size dependence at peripheral geometries. This also suggests that in the absence of momentum dependent interactions, Coulomb's interaction plays an exceedingly significant role. These results are further analyzed for nuclear dynamics at the balance point.

  4. The fragile-to-strong dynamic crossover transition in confined water: nuclear magnetic resonance results

    Science.gov (United States)

    Mallamace, F.; Broccio, M.; Corsaro, C.; Faraone, A.; Wanderlingh, U.; Liu, L.; Mou, C.-Y.; Chen, S. H.

    2006-04-01

    By means of a nuclear magnetic resonance experiment, we give evidence of the existence of a fragile-to-strong dynamic crossover transition (FST) in confined water at a temperature TL=223±2K. We have studied the dynamics of water contained in 1D cylindrical nanoporous matrices (MCM-41-S) in the temperature range 190-280K, where experiments on bulk water were so far hampered by crystallization. The FST is clearly inferred from the T dependence of the inverse of the self-diffusion coefficient of water (1/D) as a crossover point from a non-Arrhenius to an Arrhenius behavior. The combination of the measured self-diffusion coefficient D and the average translational relaxation time ⟨τT⟩, as measured by neutron scattering, shows the predicted breakdown of Stokes-Einstein relation in deeply supercooled water.

  5. PRESTO polarization transfer to quadrupolar nuclei: implications for dynamic nuclear polarization.

    Science.gov (United States)

    Perras, Frédéric A; Kobayashi, Takeshi; Pruski, Marek

    2015-09-21

    We show both experimentally and numerically on a series of model systems that in experiments involving transfer of magnetization from (1)H to the quadrupolar nuclei under magic-angle-spinning (MAS), the PRESTO technique consistently outperforms traditionally used cross polarization (CP), affording more quantitative intensities, improved lineshapes, better overall sensitivity, and straightforward optimization. This advantage derives from the fact that PRESTO circumvents the convoluted and uncooperative spin dynamics during the CP transfer under MAS, by replacing the spin-locking of quadrupolar nuclei with a single central transition selective 90° pulse and using a symmetry-based recoupling sequence in the (1)H channel. This is of particular importance in the context of dynamic nuclear polarization (DNP) NMR of quadrupolar nuclei, where the efficient transfer of enhanced (1)H polarization is desired to obtain the highest sensitivity.

  6. Bifurcations and new exact travelling wave solutions for the bidirectional wave equations

    Indian Academy of Sciences (India)

    HENG WANG; SHUHUA ZHENG; LONGWEI CHEN; XIAOCHUN HONG

    2016-11-01

    By using the method of dynamical system, the bidirectional wave equations are considered. Based on this method, all kinds of phase portraits of the reduced travelling wave system in the parametric space are given. All possible bounded travelling wave solutions such as dark soliton solutions, bright soliton solutions and periodic travelling wave solutions are obtained. With the aid of {\\it Maple} software, numerical simulations are conducted for dark soliton solutions, bright soliton solutions and periodic travelling wave solutions to the bidirectional waveequations. The results presented in this paper improve the related previous studies.

  7. 基于双向流固耦合的贯流式水轮机动力特性分析%Dynamic characteristics analysis of tubular turbine based on bidirectional fluid-solid coupling

    Institute of Scientific and Technical Information of China (English)

    郑小波; 王玲军; 翁凯

    2016-01-01

    equivalent stress and displacement of the runner is analyzed under one-way and two-way coupling. The pressure distribution of the flow field inside the runner is also analyzed. The results show that under different working conditions, the equivalent stress, displacement distribution and variation trend of the one-way coupling and two-way coupling are basically same. The maximum equivalent stress occurs on the runner blade near the hub; the maximal displacement occurs on the blade trailing edge at blade tip. The maximum equivalent stress values of the two-way coupling are separately increased by 0.16%, 0.38% and 0.82% than the one-way coupling under 3 different conditions. In the maximum displacement position, the equivalent stress difference between uncoupled and coupled systems is more significant and the equivalent stress of the two-way coupling is increased by 1.71%, 1.90% and 2.51% respectively than the one-way coupling. The maximum deformation displacement of the two-way coupling is separately increased by 0.3%, 0.43% and 0.61% than the one-way coupling. Also in the position of maximum deformation displacement, the deformation displacement is increased by 0.52%, 0.88% and 1.08% respectively. With the increase of the guide vane opening, the maximum equivalent stress and the deformation displacement are also decline. At the same time, the difference of the equivalent stress values calculated under the 2 kinds of coupling is even more significant with the increase of the maximum displacement difference between unidirectional and bidirectional coupling. It is verified that the size of displacement and the relative displacement difference in solving the runner dynamic stress is a key factor to the difference between two methods of coupling. The maximum equivalent stress peak appears 4 times within a time period, just the same as the number of blades under 3 kinds of conditions. It shows that the maximum equivalent stress with time is affected by the number of blades. The

  8. Logical operations with single x-ray photons via dynamically-controlled nuclear resonances.

    Science.gov (United States)

    Gunst, Jonas; Keitel, Christoph H; Pálffy, Adriana

    2016-04-27

    Photonic qubits lie at the heart of quantum information technology, often encoding information in their polarization state. So far, only low-frequency optical and infrared photons have been employed as flying qubits, as the resources that are at present easiest to control. With their essentially different way of interacting with matter, x-ray qubits would bear however relevant advantages: they are extremely robust, penetrate deep through materials, and can be focused down to few-nm waveguides, allowing unprecedented miniaturization. Also, x-rays are resonant to nuclear transitions, which are very well isolated from the environment and present long coherence times. Here, we show theoretically that x-ray polarization qubits can be dynamically controlled by nuclear Mössbauer resonances. The control knob is played by nuclear hyperfine magnetic fields, that allow via fast rotations precise processing of single x-ray quanta polarization. With such rotations, single-qubit and binary logical operations such as a destructive C-NOT gate can be implemented.

  9. Simultaneous Acquisition of Multi-nuclei Enhanced NMR/MRI by Solution State Dynamic Nuclear Polarization

    CERN Document Server

    He, Yugui; Feng, Jiwen; Huang, Chongyang; Chen, Fang; Liu, Maili; Liu, Chaoyang

    2015-01-01

    Dynamic nuclear polarization (DNP) has become a very important hyperpolarization method because it can dramatically increase the sensitivity of nuclear magnetic resonance (NMR) of various molecules. Liquid-state DNP based on Overhauser effect is capable of directly enhancing polarizations of all kinds of nuclei in the system. The combination of simultaneous Overhauser multi-nuclei enhancements with the multi-nuclei parallel acquisitions provides a variety of important applications in both MR spectroscopy (MRS) and image (MRI). Here we present two simple illustrative examples for simultaneously enhanced multi-nuclear spectra and images to demonstrate the principle and superiority. We have observed very large simultaneous DNP enhancements for different nuclei, such as 1H and 23Na, 1H and 31P, 19F and 31P, especially for the first time to report sodium ion enhancement in liquid. We have also obtained the simultaneous imaging of 19H and 31P at low field by solution-state DNP for the first time. This method can ob...

  10. Bidirectional Partial Generalized Synchronization in Chaotic and Hyperchaotic Systems via a New Scheme

    Institute of Scientific and Technical Information of China (English)

    WANG Qi

    2006-01-01

    In this paper, a bidirectional partial generalized (lag, complete, and anticipated) synchronization of a class of continuous-time systems is defined. Then based on the active control idea, a new systematic and concrete scheme is developed to achieve bidirectional partial generalized (lag, complete, and anticipated) synchronization between two chaotic systems or between chaotic and hyperchaotic systems. With the help of symbolic-numerical computation,we choose the modified Chua system, Lorenz system, and the hyperchaotic Tamasevicius-Namajunas-Cenys system to illustrate the proposed scheme. Numerical simulations are used to verify the effectiveness of the proposed scheme. It is interesting that partialchaos synchronization not only can take place between two chaotic systems, but also can take place between chaotic and hyperchaotic systems. The proposed scheme can also be extended to research bidirectional partial generalized (lag, complete, and anticipated) synchronization between other dynamical systems.

  11. Regulation of β-catenin nuclear dynamics by GSK-3β involves a LEF-1 positive feedback loop.

    Science.gov (United States)

    Jamieson, Cara; Sharma, Manisha; Henderson, Beric R

    2011-08-01

    Nuclear localization of β-catenin is integral to its role in Wnt signaling and cancer. Cellular stimulation by Wnt or lithium chloride (LiCl) inactivates glycogen synthase kinase-3β (GSK-3β), causing nuclear accumulation of β-catenin and transactivation of genes that transform cells. β-catenin is a shuttling protein; however, the mechanism by which GSK-3β regulates β-catenin nuclear dynamics is poorly understood. Here, fluorescence recovery after photobleaching assays were used to measure the β-catenin-green fluorescent protein dynamics in NIH 3T3 cells before and after GSK-3β inhibition. We show for the first time that LiCl and Wnt3a cause a specific increase in β-catenin nuclear retention in live cells and in fixed cells after detergent extraction. Moreover, LiCl reduced the rate of nuclear export but did not affect import, hence biasing β-catenin transport toward the nucleus. Interestingly, the S45A mutation, which blocks β-catenin phosphorylation by GSK-3β, did not alter nuclear retention or transport, implying that GSK-3β acts through an independent regulator. We compared five nuclear binding partners and identified LEF-1 as the key mediator of Wnt3a and LiCl-induced nuclear retention of β-catenin. Thus, Wnt stimulation triggered a LEF-1 positive feedback loop to enhance the nuclear chromatin-retained pool of β-catenin by 100-300%. These findings shed new light on regulation of β-catenin nuclear dynamics.

  12. Dynamic Nuclear Polarization (DNP) solid-state NMR spectroscopy, a new approach to study humic material?

    Science.gov (United States)

    Knicker, Heike; Lange, Sascha; van Rossum, Barth; Oschkinat, Hartmut

    2016-04-01

    Compared to solution NMR spectroscopy, solid-state NMR spectra suffer from broad resonance lines and low resolution. This could be overcome by the use of 2-dimenstional solid-state NMR pulse sequences. Until recently, this approach has been unfeasible as a routine tool in soil chemistry, mainly because of the low NMR sensitivity of the respective samples. A possibility to circumvent those sensitivity problems represents high-field Dynamic Nuclear Polarization (DNP) solid-state NMR spectroscopy (Barnes et al., 2008), allowing considerable signal enhancements (Akbey et al., 2010). This is achieved by a microwave-driven transfer of polarization from a paramagnetic center to nuclear spins. Application of DNP to MAS spectra of biological systems (frozen solutions) showed enhancements of the factor 40 to 50 (Hall et al., 1997). Enhancements of this magnitude, thus may enable the use of at least some of the 2D solid-state NMR techniques that are presently already applied for pure proteins but are difficult to apply to soil peptides in their complex matrix. After adjusting the required acquisition parameters to the system "soil organic matter", lower but still promising enhancement factors were achieved. Additional optimization was performed and allowed the acquisition of 2D 13C and 15N solid-state NMR spectra of humified 13C and 15N enriched plant residues. Within the present contribution, the first solid-state DNP NMR spectra of humic material are presented. Those data demonstrate the great potential of this approach which certainly opens new doors for a better understanding of biochemical processes in soils, sediments and water. Akbey, Ü., Franks, W.T., Linden, A., Lange, S., Griffin, R.G., van Rossum, B.-J., Oschkinat, H., 2010. Dynamic nuclear polarization of deuterated proteins. Angewandte Chemie International Edition 49, 7803-7806. Barnes, A.B., De Paëpe, G., van der Wel, P.C.A., Hu, K.N., Joo, C.G., Bajaj, V.S., Mak-Jurkauskas, M.L., Sirigiri, J.R., Herzfeld, J

  13. High temperature spin dynamics in linear magnetic chains, molecular rings, and segments by nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Adelnia, Fatemeh; Lascialfari, Alessandro [Dipartimento di Fisica, Università degli Studi di Milano and INSTM, Milano (Italy); Dipartimento di Fisica, Università degli Studi di Pavia and INSTM, Pavia (Italy); Mariani, Manuel [Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna (Italy); Ammannato, Luca; Caneschi, Andrea; Rovai, Donella [Dipartimento di Chimica, Università degli Studi di Firenze and INSTM, Firenze (Italy); Winpenny, Richard; Timco, Grigore [School of Chemistry, The University of Manchester, Manchester (United Kingdom); Corti, Maurizio, E-mail: maurizio.corti@unipv.it; Borsa, Ferdinando [Dipartimento di Fisica, Università degli Studi di Pavia and INSTM, Pavia (Italy)

    2015-05-07

    We present the room temperature proton nuclear magnetic resonance (NMR) nuclear spin-lattice relaxation rate (NSLR) results in two 1D spin chains: the Heisenberg antiferromagnetic (AFM) Eu(hfac){sub 3}NITEt and the magnetically frustrated Gd(hfac){sub 3}NITEt. The NSLR as a function of external magnetic field can be interpreted very well in terms of high temperature spin dynamics dominated by a long time persistence of the decay of the two-spin correlation function due to the conservation of the total spin value for isotropic Heisenberg chains. The high temperature spin dynamics are also investigated in Heisenberg AFM molecular rings. In both Cr{sub 8} closed ring and in Cr{sub 7}Cd and Cr{sub 8}Zn open rings, i.e., model systems for a finite spin segment, an enhancement of the low frequency spectral density is found consistent with spin diffusion but the high cut-off frequency due to intermolecular anisotropic interactions prevents a detailed analysis of the spin diffusion regime.

  14. Advances and applications of dynamic-angle spinning nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Baltisberger, J.H.

    1993-06-01

    This dissertation describes nuclear magnetic resonance experiments and theory which have been developed to study quadrupolar nuclei (those nuclei with spin greater than one-half) in the solid state. Primarily, the technique of dynamic-angle spinning (DAS) is extensively reviewed and expanded upon in this thesis. Specifically, the improvement in both the resolution (two-dimensional pure-absorptive phase methods and DAS angle choice) and sensitivity (pulse-sequence development), along with effective spinning speed enhancement (again through choice of DAS conditions or alternative multiple pulse schemes) of dynamic-angle spinning experiment was realized with both theory and experimental examples. The application of DAS to new types of nuclei (specifically the {sup 87}Rb and {sup 85}Rb nuclear spins) and materials (specifically amorphous solids) has also greatly expanded the possibilities of the use of DAS to study a larger range of materials. This dissertation is meant to demonstrate both recent advances and applications of the DAS technique, and by no means represents a comprehensive study of any particular chemical problem.

  15. Sensing actin dynamics: Structural basis for G-actin-sensitive nuclear import of MAL

    Energy Technology Data Exchange (ETDEWEB)

    Hirano, Hidemi; Matsuura, Yoshiyuki, E-mail: matsuura.yoshiyuki@d.mbox.nagoya-u.ac.jp

    2011-10-22

    Highlights: {yields} MAL has a bipartite NLS that binds to Imp{alpha} in an extended conformation. {yields} Mutational analyses verified the functional significance of MAL-Imp{alpha} interactions. {yields} Induced folding and NLS-masking by G-actins inhibit nuclear import of MAL. -- Abstract: The coordination of cytoskeletal actin dynamics with gene expression reprogramming is emerging as a crucial mechanism to control diverse cellular processes, including cell migration, differentiation and neuronal circuit assembly. The actin-binding transcriptional coactivator MAL (also known as MRTF-A/MKL1/BSAC) senses G-actin concentration and transduces Rho GTPase signals to serum response factor (SRF). MAL rapidly shuttles between the cytoplasm and the nucleus in unstimulated cells but Rho-induced depletion of G-actin leads to MAL nuclear accumulation and activation of transcription of SRF:MAL-target genes. Although the molecular and structural basis of actin-regulated nucleocytoplasmic shuttling of MAL is not understood fully, it is proposed that nuclear import of MAL is mediated by importin {alpha}/{beta} heterodimer, and that G-actin competes with importin {alpha}/{beta} for the binding to MAL. Here we present structural, biochemical and cell biological evidence that MAL has a classical bipartite nuclear localization signal (NLS) in the N-terminal 'RPEL' domain containing Arg-Pro-X-X-X-Glu-Leu (RPEL) motifs. The NLS residues of MAL adopt an extended conformation and bind along the surface groove of importin-{alpha}, interacting with the major- and minor-NLS binding sites. We also present a crystal structure of wild-type MAL RPEL domain in complex with five G-actins. Comparison of the importin-{alpha}- and actin-complexes revealed that the binding of G-actins to MAL is associated with folding of NLS residues into a helical conformation that is inappropriate for importin-{alpha} recognition.

  16. Dynamic parameters test of Haiyang Nuclear Power Engineering in reactor areas, China

    Science.gov (United States)

    Zhou, N.; Zhao, S.; Sun, L.

    2012-12-01

    Haiyang Nuclear Power Project is located in Haiyang city, China. It consists of 6×1000MW AP1000 Nuclear Power generator sets. The dynamic parameters of the rockmass are essential for the design of the nuclear power plant. No.1 and No.2 reactor area are taken as research target in this paper. Sonic logging, single hole and cross-hole wave velocity are carried out respectively on the site. There are four types of rock lithology within the measured depth. They are siltstone, fine sandstone, shale and allgovite. The total depth of sonic logging is 409.8m and 2049 test points. The sound wave velocity of the rocks are respectively 5521 m/s, 5576m/s, 5318 m/s and 5576 m/s. Accroding to the statistic data, among medium weathered fine sandstone, fairly broken is majority, broken and relatively integrity are second, part of integrity. Medium weathered siltstone, relatively integrity is mojority, fairly broken is second. Medium weathered shale, fairly broken is majority, broken and relatively integrity for the next and part of integrity. Slight weathered fine sandstone, siltstone, shale and allgovite, integrity is the mojority, relatively integrity for the next, part of fairly broken.The single hole wave velocity tests are set in two boreholesin No.1 reactor area and No.2 reactor area respectively. The test depths of two holes are 2-24m, and the others are 2-40m. The wave velocity data are calculated at different depth in each holes and dynamic parameters. According to the test statistic data, the wave velocity and the dynamic parameter values of rockmass are distinctly influenced by the weathering degree. The test results are list in table 1. 3 groups of cross hole wave velocity tests are set for No.1 and 2 reactor area, No.1 reactor area: B16, B16-1, B20(Direction:175°, depth: 100m); B10, B10-1, B11(269°, 40m); B21, B21-1, B17(154°, 40m); with HB16, HB10, HB21 as trigger holes; No.2 reactor area: B47, B47-1, HB51(176°, 100m); B40, B40-1, B41(272°, 40m); B42, B42-1, B

  17. Synchronization of Chaotic Storage-Ring Free-Electron Laser by Bi-Directional Coupling Scheme with the Coupling Strength Varied Periodically

    Institute of Scientific and Technical Information of China (English)

    HUANG Liang-Yu; LUO Xiao-Shu

    2006-01-01

    @@ We analyse the chaotic dynamics of storage-ring free-electron lasers and report a bi-directional coupled scheme with the coupling strength varied periodically to synchronize two chaotic storage-ring free-electron lasers.

  18. Development and application of the dynamic system doctor to nuclear reactor probabilistic risk assessments.

    Energy Technology Data Exchange (ETDEWEB)

    Kunsman, David Marvin; Aldemir, Tunc (Ohio State University); Rutt, Benjamin (Ohio State University); Metzroth, Kyle (Ohio State University); Catalyurek, Umit (Ohio State University); Denning, Richard (Ohio State University); Hakobyan, Aram (Ohio State University); Dunagan, Sean C.

    2008-05-01

    This LDRD project has produced a tool that makes probabilistic risk assessments (PRAs) of nuclear reactors - analyses which are very resource intensive - more efficient. PRAs of nuclear reactors are being increasingly relied on by the United States Nuclear Regulatory Commission (U.S.N.R.C.) for licensing decisions for current and advanced reactors. Yet, PRAs are produced much as they were 20 years ago. The work here applied a modern systems analysis technique to the accident progression analysis portion of the PRA; the technique was a system-independent multi-task computer driver routine. Initially, the objective of the work was to fuse the accident progression event tree (APET) portion of a PRA to the dynamic system doctor (DSD) created by Ohio State University. Instead, during the initial efforts, it was found that the DSD could be linked directly to a detailed accident progression phenomenological simulation code - the type on which APET construction and analysis relies, albeit indirectly - and thereby directly create and analyze the APET. The expanded DSD computational architecture and infrastructure that was created during this effort is called ADAPT (Analysis of Dynamic Accident Progression Trees). ADAPT is a system software infrastructure that supports execution and analysis of multiple dynamic event-tree simulations on distributed environments. A simulator abstraction layer was developed, and a generic driver was implemented for executing simulators on a distributed environment. As a demonstration of the use of the methodological tool, ADAPT was applied to quantify the likelihood of competing accident progression pathways occurring for a particular accident scenario in a particular reactor type using MELCOR, an integrated severe accident analysis code developed at Sandia. (ADAPT was intentionally created with flexibility, however, and is not limited to interacting with only one code. With minor coding changes to input files, ADAPT can be linked to other

  19. Dynamic modeling efforts for system interface studies for nuclear hydrogen production.

    Energy Technology Data Exchange (ETDEWEB)

    Vilim, R. B.; Nuclear Engineering Division

    2007-08-15

    System interface studies require not only identifying economically optimal equipment configurations, which involves studying mainly full power steady-state operation, but also assessing the operability of a design during load change and startup and assessing safety-related behavior during upset conditions. This latter task is performed with a dynamic simulation code. This report reviews the requirements of such a code. It considers the types of transients that will need to be simulated, the phenomena that will be present, the models best suited for representing the phenomena, and the type of numerical solution scheme for solving the models to obtain the dynamic response of the combined nuclear-hydrogen plant. Useful insight into plant transient behavior prior to running a dynamics code is obtained by some simple methods that take into account component time constants and energy capacitances. Methods for determining reactor stability, plant startup time, and temperature response during load change, and tripping of the reactor are described. Some preliminary results are presented.

  20. Analysis and insights from a dynamical model of nuclear plant safety risk

    Energy Technology Data Exchange (ETDEWEB)

    Hess, Stephen M. [Electric Power Research Institute, 30 Bethel Road, Glen Mills, PA 19342 (United States)]. E-mail: shess@epri.com; Albano, Alfonso M. [School of Economics and Social Sciences, Singapore Management University, 90 Stamford Road, Singapore 178903 (Singapore); Gaertner, John P. [Electric Power Research Institute, 1300 Harris Boulevard, Charlotte, NC 28262 (United States)

    2007-01-15

    In this paper, we expand upon previously reported results of a dynamical systems model for the impact of plant processes and programmatic performance on nuclear plant safety risk. We utilize both analytical techniques and numerical simulations typical of the analysis of nonlinear dynamical systems to obtain insights important for effective risk management. This includes use of bifurcation diagrams to show that period doubling bifurcations and regions of chaotic dynamics can occur. We also investigate the impact of risk mitigating functions (equipment reliability and loss prevention) on plant safety risk and demonstrate that these functions are capable of improving risk to levels that are better than those that are represented in a traditional risk assessment. Next, we analyze the system response to the presence of external noise and obtain some conclusions with respect to the allocation of resources to ensure that safety is maintained at optimal levels. In particular, we demonstrate that the model supports the importance of management and regulator attention to plants that have demonstrated poor performance by providing an external stimulus to obtain desired improvements. Equally important, the model suggests that excessive intervention, by either plant management or regulatory authorities, can have a deleterious impact on safety for plants that are operating with very effective programs and processes. Finally, we propose a modification to the model that accounts for the impact of plant risk culture on process performance and plant safety risk. We then use numerical simulations to demonstrate the important safety benefits of a strong risk culture.

  1. Nuclear Dynamics Consequence Analysis (NDCA) for the Disposal of Spent Nuclear Fuel in an Underground Geologic Repository--Volume 2: Methodology and Results

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, L.L.; Wilson, J.R.; Sanchez, L.C.; Aguilar, R.; Trellue, H.R.; Cochrane, K.; Rath, J.S.

    1998-10-01

    The US Department of Energy Office of Environmental Management's (DOE/EM's) National Spent Nuclear Fuel Program (NSNFP), through a collaboration between Sandia National Laboratories (SNL) and Idaho National Engineering and Environmental Laboratory (INEEL), is conducting a systematic Nuclear Dynamics Consequence Analysis (NDCA) of the disposal of SNFs in an underground geologic repository sited in unsaturated tuff. This analysis is intended to provide interim guidance to the DOE for the management of the SNF while they prepare for final compliance evaluation. This report presents results from a Nuclear Dynamics Consequence Analysis (NDCA) that examined the potential consequences and risks of criticality during the long-term disposal of spent nuclear fuel owned by DOE-EM. This analysis investigated the potential of post-closure criticality, the consequences of a criticality excursion, and the probability frequency for post-closure criticality. The results of the NDCA are intended to provide the DOE-EM with a technical basis for measuring risk which can be used for screening arguments to eliminate post-closure criticality FEPs (features, events and processes) from consideration in the compliance assessment because of either low probability or low consequences. This report is composed of an executive summary (Volume 1), the methodology and results of the NDCA (Volume 2), and the applicable appendices (Volume 3).

  2. Nuclear Dynamics Consequence Analysis (NDCA) for the Disposal of Spent Nuclear Fuel in an Underground Geologic Repository--Volume 1: Executive Summary

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, L.L.; Wilson, J.R.; Sanchez, L.Z.; Aguilar, R.; Trellue, H.R.; Cochrane, K.; Rath, J.S.

    1998-10-01

    The US Department of Energy Office of Environmental Management's (DOE/EM's) National Spent Nuclear Fuel Program (NSNFP), through a collaboration between Sandia National Laboratories (SNL) and Idaho National Engineering and Environmental Laboratory (INEEL), is conducting a systematic Nuclear Dynamics Consequence Analysis (NDCA) of the disposal of SNFs in an underground geologic repository sited in unsaturated tuff. This analysis is intended to provide interim guidance to the DOE for the management of the SNF while they prepare for final compliance evaluation. This report presents results from a Nuclear Dynamics Consequence Analysis (NDCA) that examined the potential consequences and risks of criticality during the long-term disposal of spent nuclear fuel owned by DOE-EM. This analysis investigated the potential of post-closure criticality, the consequences of a criticality excursion, and the probability frequency for post-closure criticality. The results of the NDCA are intended to provide the DOE-EM with a technical basis for measuring risk which can be used for screening arguments to eliminate post-closure criticality FEPs (features, events and processes) from consideration in the compliance assessment because of either low probability or low consequences. This report is composed of an executive summary (Volume 1), the methodology and results of the NDCA (Volume 2), and the applicable appendices (Volume 3).

  3. Nuclear quantum effect on intramolecular hydrogen bond of hydrogen maleate anion: An ab initio path integral molecular dynamics study

    Science.gov (United States)

    Kawashima, Yukio; Tachikawa, Masanori

    2013-05-01

    Ab initio path integral molecular dynamics simulation was performed to understand the nuclear quantum effect on the hydrogen bond of hydrogen malonate anion. Static calculation predicted the proton transfer barrier as 0.12 kcal/mol. Conventional ab initio molecular dynamics simulation at 300 K found proton distribution with a double peak on the proton transfer coordinate. Inclusion of thermal effect alone elongates the hydrogen bond length, which increases the barrier height. Inclusion of nuclear quantum effect washes out this barrier, and distributes a single broad peak in the center. H/D isotope effect on the proton transfer is also discussed.

  4. Quantitative dynamic nuclear polarization‐NMR on blood plasma for assays of drug metabolism

    DEFF Research Database (Denmark)

    Lerche, Mathilde Hauge; Meier, Sebastian; Jensen, Pernille Rose

    2011-01-01

    Analytical platforms for the fast detection, identification and quantification of circulating drugs with a narrow therapeutic range are vital in clinical pharmacology. As a result of low drug concentrations, analytical tools need to provide high sensitivity and specificity. Dynamic nuclear...... polarization‐NMR (DNP‐NMR) in the form of the hyperpolarization–dissolution method should afford the sensitivity and spectral resolution for the direct detection and quantification of numerous isotopically labeled circulating drugs and their metabolites in single liquid‐state NMR transients. This study......‐scan 13C DNP‐NMR. An internal standard is used for the accurate quantification of drug and metabolite. Comparison of quantitative DNP‐NMR data with an established analytical method (liquid chromatography‐mass spectrometry) yields a Pearson correlation coefficient r of 0.99. Notably, all DNP...

  5. H-1 Dynamic Nuclear Polarization in Supercritical Ethylene at 1.4 T

    Energy Technology Data Exchange (ETDEWEB)

    Wind, Robert A.(BATTELLE (PACIFIC NW LAB)); Shi, Bai (PNNL); Hu, Jian Zhi (BATTELLE (PACIFIC NW LAB)); Solum, Mark S.(Utah, Univ Of); Ellis, Paul D.(BATTELLE (PACIFIC NW LAB)); Grant, David M.(Utah, Univ Of); Pugmire, Ronald J.(Utah, Univ Of); Taylor, Craig M.(DOE); Yonker, Clement R.(BATTELLE (PACIFIC NW LAB))

    2000-03-01

    H1 dynamic nuclear polarization (DNP) has been measured in supercritical ethylene in the pressure range 60-300 bar and in an external field of 1.4 T. A single-cell sapphire tube was used as a high pressure cell and powdered 1,3-bisdiphenylene-2-phenyl allyl(BDPA) free radicals were added and distributed at the wall of the cell. At all pressures the dominant DNP effect was a positive Overhauser enhancement, caused by proton-electron contact interactions at the fluid/solid radical interface. The observed enhancements varied from 12 at 67 bar to 17 at 300 bar. Besides the Overhauser enhancement, also a small solid state and thermal mixing enhancement were observed, indicating that part of the ethylene is absorbed at the radical surface for a prolonged time. These data indicate that DNP-enhanced NMR has the potential of extending the impact of NMR in research areas involving supercritical fluids.

  6. Reactive surface organometallic complexes observed using dynamic nuclear polarization surface enhanced NMR spectroscopy

    KAUST Repository

    Pump, Eva

    2016-08-15

    Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) is an emerging technique that allows access to high-sensitivity NMR spectra from surfaces. However, DNP SENS usually requires the use of radicals as an exogenous source of polarization, which has so far limited applications for organometallic surface species to those that do not react with the radicals. Here we show that reactive surface species can be studied if they are immobilized inside porous materials with suitably small windows, and if bulky nitroxide bi-radicals (here TEKPol) are used as the polarization source and which cannot enter the pores. The method is demonstrated by obtaining significant DNP enhancements from highly reactive complelxes [(equivalent to Si-O-)W(Me)(5)] supported on MCM-41, and effects of pore size (6.0, 3.0 and 2.5 nm) on the performance are discussed.

  7. Study of low density nuclear matter with quantum molecular dynamics : the role of the symmetry energy

    CERN Document Server

    Nandi, Rana

    2016-01-01

    We study the effect of isospin-dependent nuclear forces on the pasta phase in the inner crust of neutron stars. To this end we model the crust within the framework of quantum molecular dynamics (QMD). For maximizing the numerical performance, the newly developed code has been implemented on GPU processors. As a first application of the crust studies we investigate the dependence of the particular pasta phases on the slope of the symmetry energy slope L. To isolate the effect of different values of L, we adopt an established QMD Hamiltonian and extend it to include non-linear terms in the isospin-dependent interaction. The strengths of the isospin-dependent forces are used to adjust the asymmetry energy and slope of the matter. Our results indicate that in contrast to earlier studies the phase diagram of the pasta phase is not very sensitive to the value of L.

  8. Bubble dynamics and the quark-hadron phase transition in nuclear collisions

    CERN Document Server

    Fogaça, D A; Fariello, R; Navarra, F S

    2016-01-01

    We study the nucleation of a quark gluon plasma (QGP) phase in a hadron gas at low temperatures and high baryon densities. This kind of process will presumably happen very often in nuclear collisions at FAIR and NICA. When the right energy density (or baryon density) is reached the conversion of one phase into another is not instantaneous. It is a complex process, which involves the nucleation of bubbles of the new phase. One important element of this transition process is the rate of growth of a QGP bubble. In order to estimate it we solve the Relativistic Rayleigh$-$Plesset equation which governs the dynamics of a relativistic spherical bubble in a cold and strongly interacting medium. The baryon rich hadron gas is represented by the nonlinear Walecka model and the QGP is described by the MIT bag model and also by a mean field model of QCD.

  9. Dynamics of the tri-nuclear system at spontaneous fission of $^{252}$Cf

    CERN Document Server

    Tashkhodjaev, R B; Alpomeshev, E Kh

    2016-01-01

    To describe of dynamics of ternary fission of $^{252}$Cf an equation of motion of the tri-nuclear system is calculated. The fission of the $^{70}$Ni+$^{50}$Ca+$^{132}$Sn channel was chosen as one of the more probable channels of true ternary fission of $^{252}$Cf. The collinearity of ternary fission has been checked by analyzing results of the equation of motion. The results show that if initially all nuclei are placed collinearly (potential energy of this position is the smallest) and the component of the middle fragment's initial velocity which is perpendicular to this line, is zero then ternary fission is collinear, otherwise the non collinear ternary fission takes place.

  10. Dynamic regulation of ARGONAUTE4 within multiple nuclear bodies in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Carey F Li

    2008-02-01

    Full Text Available DNA methylation directed by 24-nucleotide small RNAs involves the small RNA-binding protein ARGONAUTE4 (AGO4, and it was previously shown that AGO4 localizes to nucleolus-adjacent Cajal bodies, sites of snRNP complex maturation. Here we demonstrate that AGO4 also localizes to a second class of nuclear bodies, called AB-bodies, which are found immediately adjacent to condensed 45S ribosomal DNA (rDNA sequences. AB-bodies also contain other proteins involved in RNA-directed DNA methylation including NRPD1b (a subunit of the RNA Polymerase IV complex, RNA PolIV, NRPD2 (a second subunit of this complex, and the DNA methyltransferase DRM2. These two classes of AGO4 bodies are structurally independent--disruption of one class does not affect the other--suggesting a dynamic regulation of AGO4 within two distinct nuclear compartments in Arabidopsis. Abolishing Cajal body formation in a coilin mutant reduced overall AGO4 protein levels, and coilin dicer-like3 double mutants showed a small decrease in DNA methylation beyond that seen in dicer-like3 single mutants, suggesting that Cajal bodies are required for a fully functioning DNA methylation system in Arabidopsis.

  11. Nonlinear Adaptive Dynamic Output-Feedback Power-Level Control of Nuclear Heating Reactors

    Directory of Open Access Journals (Sweden)

    Zhe Dong

    2013-01-01

    Full Text Available Due to the high safety performance of small nuclear reactors, there is a promising future for small reactors. Nuclear heating reactor (NHR is a small reactor that has many advanced safety features such as the integrated arrangement, natural circulation at any power levels, self-pressurization, hydraulic control rod driving, and passive residual heating removing and can be applied to the fields of district heating, seawater desalination, and electricity production. Since the NHR dynamics has strong nonlinearity and uncertainty, it is meaningful to develop the nonlinear adaptive power-level control technique. From the idea of physically based control design method, a novel nonlinear adaptive power-level control is given for the NHR in this paper. It is theoretically proved that this newly built controller does not only provide globally asymptotic closed-loop stability but is also adaptive to the system uncertainty. Numerical simulation results show the feasibility of this controller and the relationship between the performance and controller parameters.

  12. Milli-tesla NMR and spectrophotometry of liquids hyperpolarized by dissolution dynamic nuclear polarization

    Science.gov (United States)

    Zhu, Yue; Chen, Chia-Hsiu; Wilson, Zechariah; Savukov, Igor; Hilty, Christian

    2016-09-01

    Hyperpolarization methods offer a unique means of improving low signal strength obtained in low-field NMR. Here, simultaneous measurements of NMR at a field of 0.7 mT and laser optical absorption from samples hyperpolarized by dissolution dynamic nuclear polarization (D-DNP) are reported. The NMR measurement field closely corresponds to a typical field encountered during sample injection in a D-DNP experiment. The optical spectroscopy allows determination of the concentration of the free radical required for DNP. Correlation of radical concentration to NMR measurement of spin polarization and spin-lattice relaxation time allows determination of relaxivity and can be used for optimization of the D-DNP process. Further, the observation of the nuclear Overhauser effect originating from hyperpolarized spins is demonstrated. Signals from 1H and 19F in a mixture of trifluoroethanol and water are detected in a single spectrum, while different atoms of the same type are distinguished by J-coupling patterns. The resulting signal changes of individual peaks are indicative of molecular contact, suggesting a new application area of hyperpolarized low-field NMR for the determination of intermolecular interactions.

  13. Hyperpolarization of nitrogen-15 nuclei by cross polarization and dissolution dynamic nuclear polarization

    Science.gov (United States)

    Milani, Jonas; Vuichoud, Basile; Bornet, Aurélien; Melzi, Roberto; Jannin, Sami; Bodenhausen, Geoffrey

    2017-01-01

    Dynamic Nuclear Polarization (DNP) is often achieved by the direct transfer of polarization from electrons to nuclei such as 13C, induced by microwave saturation of the wings of narrow EPR lines of radicals like trityl. In the indirect approach on the other hand, DNP is used to transfer the polarization from the electrons of radicals such as nitroxides that have broad EPR lines to nuclear spins I = 1H, followed by cross-polarization (CP) from I = 1H to S = 13C or other nuclei with low gyromagnetic ratios. This approach is particularly attractive for S = 15N, since direct DNP yields modest polarizations P(15N) 2 h. In this paper, we show that CP from 1H to 15N at 1.2 K can yield P(15N) = 25% with τCP-DNP(15N) = 10-15 min. After rapid dissolution and transfer to a solution-state NMR spectrometer, a polarization P(15N) = 20% was observed at 300 K. The longitudinal relaxation times in solution can be as long as T1(15N) > 800 s in favorable cases.

  14. Micropillar displacements by cell traction forces are mechanically correlated with nuclear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qingsen; Makhija, Ekta; Hameed, F.M. [Mechanobiology Institute, National University of Singapore (Singapore); Shivashankar, G.V., E-mail: shiva.gvs@gmail.com [Mechanobiology Institute, National University of Singapore (Singapore); Department of Biological Sciences, National University of Singapore (Singapore)

    2015-05-29

    Cells sense physical cues at the level of focal adhesions and transduce them to the nucleus by biochemical and mechanical pathways. While the molecular intermediates in the mechanical links have been well studied, their dynamic coupling is poorly understood. In this study, fibroblast cells were adhered to micropillar arrays to probe correlations in the physical coupling between focal adhesions and nucleus. For this, we used novel imaging setup to simultaneously visualize micropillar deflections and EGFP labeled chromatin structure at high spatial and temporal resolution. We observed that micropillar deflections, depending on their relative positions, were positively or negatively correlated to nuclear and heterochromatin movements. Our results measuring the time scales between micropillar deflections and nucleus centroid displacement are suggestive of a strong elastic coupling that mediates differential force transmission to the nucleus. - Highlights: • Correlation between focal adhesions and nucleus studied using novel imaging setup. • Micropillar and nuclear displacements were measured at high resolution. • Correlation timescales show strong elastic coupling between cell edge and nucleus.

  15. On the nature of nuclear dissipation, as a hallmark for collective dynamics at finite excitation

    CERN Document Server

    Hofmann, H; Yamaji, S; Hofmann, Helmut; Ivanyuk, Fedor A; Yamaji, Shuhei

    1995-01-01

    We study slow collective motion of isoscalar type at finite excitation. The collective variable is parameterized as a shape degree of freedom and the mean field is approximated by a deformed shell model potential. We concentrate on situations of slow motion, as guaranteed, for instance, by the presence of a strong friction force, which allows us to apply linear response theory. The prediction for nuclear dissipation of some models of internal motion are contrasted. They encompass such opposing cases as that of pure independent particle motion and the one of "collisional dominance". For the former the wall formula appears as the macroscopic limit, which is here simulated through Strutinsky smoothing procedures. It is argued that this limit hardly applies to the actual nuclear situation. The reason is found in large collisional damping present for nucleonic dynamics at finite temperature T. The level structure of the mean field as well as the T-dependence of collisional damping determine the T-dependence of fri...

  16. Dynamic Length Changes of Telomeres and Their Nuclear Organization in Chronic Myeloid Leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Samassekou, Oumar [Manitoba Institute of Cell Biology, Cancer Care Manitoba, Department of Physiology, University of Manitoba, Winnipeg, Manitoba R3E 0V9 (Canada)

    2013-08-22

    Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm characterized by the t(9;22) translocation. As in most cancers, short telomeres are one of the features of CML cells, and telomere shortening accentuates as the disease progresses from the chronic phase to the blastic phase. Although most individual telomeres are short, some of them are lengthened, and long individual telomeres occur non-randomly and might be associated with clonal selection. Telomerase is the main mechanism used to maintain telomere lengths, and its activity increases when CML evolves toward advanced stages. ALT might be another mechanism employed by CML cells to sustain the homeostasis of their telomere lengths and this mechanism seems predominant at the early stage of leukemogenesis. Also, telomerase and ALT might jointly act to maintain telomere lengths at the chronic phase, and as CML progresses, telomerase becomes the major mechanism. Finally, CML cells display an altered nuclear organization of their telomeres which is characterized by the presence of high number of telomeric aggregates, a feature of genomic instability, and differential positioning of telomeres. CML represents a good model to study mechanisms responsible for dynamic changes of individual telomere lengths and the remodeling of telomeric nuclear organization throughout cancer progression.

  17. Dynamic localization of tripartite motif-containing 22 in nuclear and nucleolar bodies

    Energy Technology Data Exchange (ETDEWEB)

    Sivaramakrishnan, Gayathri; Sun, Yang; Tan, Si Kee [School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551 (Singapore); Lin, Valerie C.L., E-mail: cllin@ntu.edu.sg [School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551 (Singapore)

    2009-05-01

    Tripartite motif-containing 22 (TRIM22) exhibits antiviral and growth inhibitory properties, but there has been no study on the localization and dynamics of the endogenous TRIM22 protein. We report here that TRIM22 is dramatically induced by progesterone in MDA-MB-231-derived ABC28 cells and T47D cells. This induction was associated with an increase in TRIM22 nuclear bodies (NB), and an even more prominent increase in nucleolar TRIM22 bodies. Distinct endogenous TRIM22 NB were also demonstrated in several other cell lines including MCF7 and HeLa cells. These TRIM22 NB resemble Cajal bodies, co-localized with these structures and co-immunoprecipitated with p80-coilin. However, IFN{gamma}-induced TRIM22 in HeLa and MCF7 cells did not form NB, implying the forms and distribution of TRIM22 are regulated by specific cellular signals. This notion is also supported by the observation that TRIM22 NB undergoes dynamic cell-cycle dependent changes in distribution such that TRIM22 NB started to form in early G0/G1 but became dispersed in the S-phase. In light of its potential antiviral and antitumor properties, the findings here provide an interesting gateway to study the relationship between the different forms and functions of TRIM22.

  18. High dynamic range magnetometry with a single nuclear spin in diamond

    Energy Technology Data Exchange (ETDEWEB)

    Waldherr, Gerald; Beck, Johannes; Neumann, Philipp; Nitsche, Matthias; Wrachtrup, Joerg [3. Physikalisches Institut, Universitaet Stuttgart, 70569 Stuttgart (Germany); Said, Ressa S. [Institut fuer Quanten-Informationsverarbeitung, Universitaet Ulm, 89081 Ulm (Germany); Twamley, Jason [Centre for Engineered Quantum Systems, Faculty of Science, Macquarie University, Sydney (Australia); Jelezko, Fedor [Institut fuer Quantenoptik, Universitaet Ulm, 89073 Ulm (Germany)

    2012-07-01

    Sensors based on the nitrogen-vacancy (NV) defect in diamond are being developed to measure weak magnetic and electric fields at nanoscale. However, such sensors rely on measurements of a shift in the Lamor frequency of the defect, so an accumulation of quantum phase causes the measurement signal to exhibit a periodic modulation. This means that the measurement time is either restricted to half of one oscillation period, which limits accuracy, or that the magnetic field range must be known in advance. Moreover, the precision increases only slowly, as T{sup -0.5}, with the measurement time T. We implement a quantum phase estimation algorithm on a single nuclear spin in diamond to combine both high sensitivity and high dynamic range. By achieving a scaling of the precision with time to T{sup -0.85}, we improve the sensitivity by a factor of 7.4, for an accessible field range of 16 mT, or alternatively, we improve the dynamic range by a factor of 130 for a sensitivity of 2.5 {mu}T/Hz{sup 0.5}. These methods are applicable to a variety of field detection schemes, and do not require entanglement.

  19. Electron momentum spectroscopy of dimethyl ether taking account of nuclear dynamics in the electronic ground state

    Energy Technology Data Exchange (ETDEWEB)

    Morini, Filippo; Deleuze, Michael Simon, E-mail: michael.deleuze@uhasselt.be [Center of Molecular and Materials Modelling, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek (Belgium); Watanabe, Noboru; Kojima, Masataka; Takahashi, Masahiko [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan)

    2015-10-07

    The influence of nuclear dynamics in the electronic ground state on the (e,2e) momentum profiles of dimethyl ether has been analyzed using the harmonic analytical quantum mechanical and Born-Oppenheimer molecular dynamics approaches. In spite of fundamental methodological differences, results obtained with both approaches consistently demonstrate that molecular vibrations in the electronic ground state have a most appreciable influence on the momentum profiles associated to the 2b{sub 1}, 6a{sub 1}, 4b{sub 2}, and 1a{sub 2} orbitals. Taking this influence into account considerably improves the agreement between theoretical and newly obtained experimental momentum profiles, with improved statistical accuracy. Both approaches point out in particular the most appreciable role which is played by a few specific molecular vibrations of A{sub 1}, B{sub 1}, and B{sub 2} symmetries, which correspond to C–H stretching and H–C–H bending modes. In line with the Herzberg-Teller principle, the influence of these molecular vibrations on the computed momentum profiles can be unraveled from considerations on the symmetry characteristics of orbitals and their energy spacing.

  20. A nuclear magnetic resonance study of the dynamics of organofluorine interactions with a dissolved humic acid.

    Science.gov (United States)

    Longstaffe, James G; Courtier-Murias, Denis; Simpson, Andre J

    2016-02-01

    A quantitative understanding of the dynamics of the interactions between organofluorine compounds and humic acids will contribute to an improved understanding of the role that Natural Organic Matter plays as a mediator in the fate, transport and distribution of these contaminants in the environment. Here, Nuclear Magnetic Resonance (NMR) spectroscopy-based diffusion measurements are used to estimate the association dynamics between dissolved humic acid and selected organofluorine compounds: pentafluoroaniline, pentafluorophenol, potassium perfluorooctane sulfonate, and perfluorooctanoic acid. Under the conditions used here, the strength of the association with humic acid increases linearly as temperature decreases for all compounds except for perfluorooctanoic acid, which exhibits divergent behavior with a non-linear decrease in the extent of interaction as temperature decreases. A general interaction mechanism controlled largely by desolvation effects is suggested for all compounds examined here except for perfluorooctanoic acid, which exhibits a specific mode of interaction consistent with a proteinaceous binding site. Reverse Heteronuclear Saturation Transfer Difference NMR is used to confirm the identity and nature of the humic acid binding sites.

  1. Nuclear dynamics investigation of the initial electron transfer in the cyclobutane pyrimidine dimer lesion repair process by photolyases

    CERN Document Server

    Joubert-Doriol, Loic; Olivucci, Massimo; Izmaylov, Artur F

    2016-01-01

    Photolyases are proteins capable of harvesting the sunlight to repair DNA damages caused by UV light. In this work we focus on the first step in the repair process of the cyclobutane pyrimidine dimer photoproduct (CPD) lesion, which is an electron transfer (ET) from a flavine cofactor to CPD, and study the role of various nuclear degrees of freedom (DOF) in this step. The ET step has been experimentally studied using transient spectroscopy and the corresponding data provide excellent basis for testing the quality of quantum dynamical models. Based on previous theoretical studies of electronic structure and conformations of the protein active site, we present a procedure to build a diabatic Hamiltonian for simulating the ET reaction in a molecular complex mimicking the enzyme's active site. We generate a reduced nuclear dimensional model that provides a first non-empirical quantum dynamical description of the structural features influencing the ET rate. By varying the nuclear DOF parametrization in the model t...

  2. 1H-NMR and photochemically-induced dynamic nuclear polarization studies on bovine pancreatic phospholipase A2

    NARCIS (Netherlands)

    Egmond, M.R.; Slotboom, A.J.; Haas, G.H. de; Dijkstra, Klaas; Kaptein, R.

    1980-01-01

    Proton-NMR resonances of trytophan 3 and tyrosine 69 in bovine pancreatic phospholipase A2, its pro-enzyme and in Ala1-transaminated protein were assigned using photochemically-induced dynamic nuclear polarization (photo-CIDNP) as such or in combination with spin-echo measurements. In addition assig

  3. Tunable 13C/1H dual channel matching circuit for dynamic nuclear polarization system with cross-polarization

    DEFF Research Database (Denmark)

    Rybalko, Oleksandr; Bowen, Sean; Zhurbenko, Vitaliy

    2016-01-01

    In this paper we report initial results of design and practical implementation of tuning and matching circuit to estimate a performance of Dynamic Nuclear Polarization (DNP) at a magnetic field of 6.7 T. It is shown that developed circuit for signal observation is compact, easy to make and provides...

  4. Engineering light-inducible nuclear localization signals for precise spatiotemporal control of protein dynamics in living cells.

    Science.gov (United States)

    Niopek, Dominik; Benzinger, Dirk; Roensch, Julia; Draebing, Thomas; Wehler, Pierre; Eils, Roland; Di Ventura, Barbara

    2014-07-14

    The function of many eukaryotic proteins is regulated by highly dynamic changes in their nucleocytoplasmic distribution. The ability to precisely and reversibly control nuclear translocation would, therefore, allow dissecting and engineering cellular networks. Here we develop a genetically encoded, light-inducible nuclear localization signal (LINuS) based on the LOV2 domain of Avena sativa phototropin 1. LINuS is a small, versatile tag, customizable for different proteins and cell types. LINuS-mediated nuclear import is fast and reversible, and can be tuned at different levels, for instance, by introducing mutations that alter AsLOV2 domain photo-caging properties or by selecting nuclear localization signals (NLSs) of various strengths. We demonstrate the utility of LINuS in mammalian cells by controlling gene expression and entry into mitosis with blue light.

  5. Fluctuation effects in bidirectional cargo transport

    CERN Document Server

    Klein, Sarah; Santen, Ludger

    2014-01-01

    We discuss a theoretical model for bidirectional cargo transport in biological cells, which is driven by teams of molecular motors and subject to thermal fluctuations. The model describes explicitly the directed motion of the molecular motors on the filament. The motor-cargo coupling is implemented via linear springs. By means of extensive Monte Carlo simulations we show that the model describes the experimentally observed regimes of anomalous diffusion, i.e. subdiffusive behavior at short times followed by superdiffusion at intermediate times. The model results indicate that subdiffuse regime is induced by thermal fluctuations while the superdiffusive motion is generated by correlations of the motors' activity. We also tested the efficiency of bidirectional cargo transport in crowded areas by measuring its ability to pass barriers with increased viscosity. Our results show a remarkable gain of efficiency for high viscosities.

  6. Traffic Grooming in Bidirectional WDM Ring Networks

    CERN Document Server

    Bermond, Jean-Claude; Valls, Ignasi Sau

    2009-01-01

    We study the minimization of ADMs (Add-Drop Multiplexers) in optical WDM bidirectional rings considering symmetric shortest path routing and all-to-all unitary requests. We precisely formulate the problem in terms of graph decompositions, and state a general lower bound for all the values of the grooming factor $C$ and $N$, the size of the ring. We first study exhaustively the cases C=1, $C = 2$, and C=3, providing improved lower bounds, optimal constructions for several infinite families, as well as asymptotically optimal constructions and approximations. We then study the case $C>3$, focusing specifically on the case $C = k(k+1)/2$ for some $k \\geq 1$. We give optimal decompositions for several congruence classes of $N$ using the existence of some combinatorial designs. We conclude with a comparison of the cost functions in unidirectional and bidirectional WDM rings.

  7. Design and Implementation of Bidirectional Dijkstra Algorithm

    Institute of Scientific and Technical Information of China (English)

    付梦印; 李杰; 周培德

    2003-01-01

    Bidirectional Dijkstra algorithm whose time complexity is (1)/(8)O(n2) is proposed. The theory foundation is that the classical Dijkstra algorithm has not any directional feature during searching the shortest path. The algorithm takes advantage of the adjacent link and the mechanism of bidirectional search, that is, the algorithm processes the positive search from start point to destination point and the negative search from destination point to start point at the same time. Finally, combining with the practical application of route-planning algorithm in embedded real-time vehicle navigation system (ERTVNS), one example of its practical applications is given, analysis in theory and the experimental results show that compared with the Dijkstra algorithm, the new algorithm can reduce time complexity, and guarantee the searching precision, it satisfies the needs of ERTVNS.

  8. Bidirectional dc-to-dc Power Converter

    Science.gov (United States)

    Griesbach, C. R.

    1986-01-01

    Solid-state, series-resonant converter uses high-voltage thyristors. Converter used either to convert high-voltage, low-current dc power to lowvoltage, high current power or reverse. Taking advantage of newly-available high-voltage thyristors to provide better reliability and efficiency than traditional converters that use vacuum tubes as power switches. New converter essentially maintenance free and provides greatly increased mean time between failures. Attractive in industrial applications whether or not bidirectional capability is required.

  9. Theory for cross effect dynamic nuclear polarization under magic-angle spinning in solid state nuclear magnetic resonance: the importance of level crossings.

    Science.gov (United States)

    Thurber, Kent R; Tycko, Robert

    2012-08-28

    We present theoretical calculations of dynamic nuclear polarization (DNP) due to the cross effect in nuclear magnetic resonance under magic-angle spinning (MAS). Using a three-spin model (two electrons and one nucleus), cross effect DNP with MAS for electron spins with a large g-anisotropy can be seen as a series of spin transitions at avoided crossings of the energy levels, with varying degrees of adiabaticity. If the electron spin-lattice relaxation time T(1e) is large relative to the MAS rotation period, the cross effect can happen as two separate events: (i) partial saturation of one electron spin by the applied microwaves as one electron spin resonance (ESR) frequency crosses the microwave frequency and (ii) flip of all three spins, when the difference of the two ESR frequencies crosses the nuclear frequency, which transfers polarization to the nuclear spin if the two electron spins have different polarizations. In addition, adiabatic level crossings at which the two ESR frequencies become equal serve to maintain non-uniform saturation across the ESR line. We present analytical results based on the Landau-Zener theory of adiabatic transitions, as well as numerical quantum mechanical calculations for the evolution of the time-dependent three-spin system. These calculations provide insight into the dependence of cross effect DNP on various experimental parameters, including MAS frequency, microwave field strength, spin relaxation rates, hyperfine and electron-electron dipole coupling strengths, and the nature of the biradical dopants.

  10. Properties of Coupled Oscillator Model for Bidirectional Associative Memory

    Science.gov (United States)

    Kawaguchi, Satoshi

    2016-08-01

    In this study, we consider the stationary state and dynamical properties of a coupled oscillator model for bidirectional associative memory. For the stationary state, we apply the replica method to obtain self-consistent order parameter equations. The theoretical results for the storage capacity and overlap agree well with the numerical simulation. For the retrieval process, we apply statistical neurodynamics to include temporal noise correlations. For the successful retrieval process, the theoretical result obtained with the fourth-order approximation qualitatively agrees with the numerical simulation. However, for the unsuccessful retrieval process, higher-order noise correlations suppress severely; therefore, the maximum value of the overlap and the relaxation time are smaller than those of the numerical simulation. The reasons for the discrepancies between the theoretical result and numerical simulation, and the validity of our analysis are discussed.

  11. COMPONENTWISE STABILITY OF DISCRETE-TIME INTERVAL BIDIRECTIONAL ASSOCIATIVE MEMORIES

    Directory of Open Access Journals (Sweden)

    Mihaela-Hanako MATCOVSCHI

    2004-12-01

    Full Text Available The componentwise stability is a special type of asymptotic stability, which incorporates the positive invariance of certain time-dependent rectangular sets with respect to the state space trajectories. The paper develops the analysis of componentwise stability for discrete-time Bidirectional Associative Memory (BAM neural networks with interval type parameters, providing criteria that allow monitoring the evolution of each state-space variable towards the equilibrium point. These criteria are formulated in terms of Schur stability of a test matrix adequately built from the intervals expressing the parameter uncertainties. Our approach represents a refinement of the classical results in stability theory, since the time-dependence of the considered invariant sets makes it possible to give a qualitative characterization of the dynamics at the level of the state vector components.

  12. Bidirectional optimization of the melting spinning process.

    Science.gov (United States)

    Liang, Xiao; Ding, Yongsheng; Wang, Zidong; Hao, Kuangrong; Hone, Kate; Wang, Huaping

    2014-02-01

    A bidirectional optimizing approach for the melting spinning process based on an immune-enhanced neural network is proposed. The proposed bidirectional model can not only reveal the internal nonlinear relationship between the process configuration and the quality indices of the fibers as final product, but also provide a tool for engineers to develop new fiber products with expected quality specifications. A neural network is taken as the basis for the bidirectional model, and an immune component is introduced to enlarge the searching scope of the solution field so that the neural network has a larger possibility to find the appropriate and reasonable solution, and the error of prediction can therefore be eliminated. The proposed intelligent model can also help to determine what kind of process configuration should be made in order to produce satisfactory fiber products. To make the proposed model practical to the manufacturing, a software platform is developed. Simulation results show that the proposed model can eliminate the approximation error raised by the neural network-based optimizing model, which is due to the extension of focusing scope by the artificial immune mechanism. Meanwhile, the proposed model with the corresponding software can conduct optimization in two directions, namely, the process optimization and category development, and the corresponding results outperform those with an ordinary neural network-based intelligent model. It is also proved that the proposed model has the potential to act as a valuable tool from which the engineers and decision makers of the spinning process could benefit.

  13. Nuclear Wavepacket Dynamics of Alkali Adsorbates on Metal Surfaces Studied by Time-Resolved Second Harmonic Generation

    Directory of Open Access Journals (Sweden)

    Kazuya Watanabe

    2012-01-01

    Full Text Available This paper reviews recent efforts to understand the dynamics of coherent surface vibrations of alkali atoms adsorbed on metal surfaces. Time-resolved second harmonic generation is used for the coherent excitation and detection of the nuclear wavepacket dynamics of the surface modes. The principles of the measurement and the experimental details are described. The main focus is on coverage and excitation photon energy dependences of the coherent phonon dynamics for Na-, K-, and Cs-covered Cu(111. The excitation mechanism of the coherent phonon has been revealed by the ultrafast time-domain technique and theoretical modelings.

  14. Extended-life nuclear air cleaning filters via dynamic exclusion prefilters

    Energy Technology Data Exchange (ETDEWEB)

    Wright, S.R.; Crouch, H.S.; Bond, J.H. [Micro Composite Materials Corp., Durham, NC (United States)

    1997-08-01

    The primary objective of this investigation was to ascertain if a dynamic, self-cleaning particulate exclusion precleaner, designed for relatively large dust removal (2 to 100+ {mu}m diameter particles) from helicopter turbine inlets, could be extended to submicron filtration. The improved device could be used as a prefilter for HEPA filtration systems, significantly increasing service life. In nuclear air cleaning, its use would reduce the amount of nuclear particulate matter that would otherwise be entrapped in the HEPA filter cartridge/panel, causing fouling and increased back pressure, as well as requiring subsequent disposal of the contaminated media at considerable expense. A unique (patent-pending) mechanical separation device has recently been developed to extract particulate matter from fluid process streams based on a proprietary concept called Boundary Layer Momentum Transfer (BLMT). The device creates multiple boundary layers that actively exclude particles from entering the perimeter of the device, while allowing air to traverse the boundaries relatively unimpeded. A modified two-dimensional (2-D) computerized flow simulation model was used to assist in the prototype design. Empirical results are presented from particle breakthrough and AP experiments obtained from a reduced-scale prototype filter. Particles larger than 0.23 {mu}m were actively excluded by the prototype, but at a higher pressure drop than anticipated. Experimental data collected indicates that the filter housing and the inlet flow configuration may contribute significantly to improvements in device particle separation capabilities. Furthermore, preliminary experiments have shown that other downstream pressure drop considerations (besides those just across the spinning filtration disks) must be included to accurately portray the AP across the device. Further detailed quantitative investigations on a larger scale (1,000 CFM) prototype are warranted. 3 refs., 5 figs., 2 tabs.

  15. Dynamic distribution of nuclear coactivator 4 during mitosis: association with mitotic apparatus and midbodies.

    Directory of Open Access Journals (Sweden)

    Alexandra Kollara

    Full Text Available The cytoplasmic localization of Nuclear Receptor Coactivator 4 (NcoA4, also referred to as androgen receptor associated protein 70 (ARA70, indicates it may possess activities in addition to its role within the nucleus as a transcriptional enhancer. Towards identifying novel functions of NcoA4, we performed an in silico analysis of its amino acid sequence to identify potential functional domains and related proteins, and examined its subcellular distribution throughout the cell cycle. NcoA4 has no known or predicted functional or structural domains with the exception of an LxxLL and FxxLF nuclear receptor interaction motif and an N-terminal putative coiled-coil domain. Phylogenetic analysis indicated that NcoA4 has no paralogs and that a region referred to as ARA70-I family domain, located within the N-terminus and overlapping with the coiled-coil domain, is evolutionarily conserved in metazoans ranging from cnidarians to mammals. An adjacent conserved region, designated ARA70-II family domain, with no significant sequence similarity to the ARA70-I domain, is restricted to vertebrates. We demonstrate NcoA4 co-localizes with microtubules and microtubule organizing centers during prophase. Strong NcoA4 accumulation at the centrosomes was detected during interphase and telophase, with decreased levels at metaphase and anaphase. NcoA4 co-localized with tubulin and acetylated tubulin to the mitotic spindles during metaphase and anaphase, and to midbodies during telophase. Consistent with these observations, we demonstrated an interaction between NcoA4 and α-tubulin. Co-localization was not observed with microfilaments. These findings indicate a dynamic distribution of NcoA4 with components of the mitotic apparatus that is consistent with a potential non-transcriptional regulatory function(s during cell division, which may be evolutionarily conserved.

  16. Empirical analysis of the lane formation process in bidirectional pedestrian flow

    Science.gov (United States)

    Feliciani, Claudio; Nishinari, Katsuhiro

    2016-09-01

    This paper presents an experimental study on pedestrian bidirectional streams and the mechanisms leading to spontaneous lane formation by examining the flow formed by two groups of people walking toward each other in a mock corridor. Flow ratio is changed by changing each group size while maintaining comparable total flow and density. By tracking the trajectories of each pedestrian and analyzing the data obtained, five different phases were recognized as contributing to the transition from unidirectional to bidirectional flow including the spontaneous creation and dissolution of lanes. It has been shown that a statistical treatment is required to understand the fundamental characteristics of pedestrian dynamics and some two-dimensional quantities such as order parameter and rotation range were introduced to allow a more complete analysis. All the quantities observed showed a clear relationship with flow ratio and helped distinguishing between the different characteristic phases of the experiment. Results show that balanced bidirectional flow becomes the most stable configuration after lanes are formed, but the lane creation process requires pedestrians to laterally move to a largest extent compared to low flow-ratio configurations. This finding allows us to understand the reasons why balanced bidirectional flow is efficient at low densities, but quickly leads to deadlock formation at high densities.

  17. Bidirectional Synaptic Structural Plasticity after Chronic Cocaine Administration Occurs through Rap1 Small GTPase Signaling.

    Science.gov (United States)

    Cahill, Michael E; Bagot, Rosemary C; Gancarz, Amy M; Walker, Deena M; Sun, HaoSheng; Wang, Zi-Jun; Heller, Elizabeth A; Feng, Jian; Kennedy, Pamela J; Koo, Ja Wook; Cates, Hannah M; Neve, Rachael L; Shen, Li; Dietz, David M; Nestler, Eric J

    2016-02-03

    Dendritic spines are the sites of most excitatory synapses in the CNS, and opposing alterations in the synaptic structure of medium spiny neurons (MSNs) of the nucleus accumbens (NAc), a primary brain reward region, are seen at early versus late time points after cocaine administration. Here we investigate the time-dependent molecular and biochemical processes that regulate this bidirectional synaptic structural plasticity of NAc MSNs and associated changes in cocaine reward in response to chronic cocaine exposure. Our findings reveal key roles for the bidirectional synaptic expression of the Rap1b small GTPase and an associated local synaptic protein translation network in this process. The transcriptional mechanisms and pathway-specific inputs to NAc that regulate Rap1b expression are also characterized. Collectively, these findings provide a precise mechanism by which nuclear to synaptic interactions induce "metaplasticity" in NAc MSNs, and we reveal the specific effects of this plasticity on reward behavior in a brain circuit-specific manner.

  18. SU-E-J-61: Electrodynamics and Nano-Scale Fluid Dynamics in Protein Localization of Nuclear Pore Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, J; Gatenby, R [Moffitt Cancer Research Institute, Tampa, FL (United States)

    2014-06-01

    Purpose: To develop a simulation to catalyze a reevaluation of common assumptions about 3 dimensional diffusive processes and help cell biologists gain a more nuanced, intuitive understanding of the true physical hurdles of protein signaling cascades. Furthermore, to discuss the possibility of intracellular electrodynamics as a critical, unrecognized component of cellular biology and protein dynamics that is necessary for optimal information flow from the cell membrane to the nucleus. Methods: The Unity 3D gaming physics engine was used to build an accurate virtual scale model of the cytoplasm within a few hundred nanometers of the nuclear membrane. A cloud of simulated pERK proteins is controlled by the physics simulation, where diffusion is based on experimentally measured values and the electrodynamics are based on theoretical nano-fluid dynamics. The trajectories of pERK within the cytoplasm and through the 1250 nuclear pores on the nuclear surface is recorded and analyzed. Results: The simulation quickly demonstrates that pERKs moving solely by diffusion will rarely locate and come within capture distance of a nuclear pore. The addition of intracellular electrodynamics between charges on the nuclear pore complexes and on pERKs increases the number of successful translocations by allowing the electro-physical attractive effects to draw in pERKs from the cytoplasm. The effects of changes in intracellular shielding ion concentrations allowed for estimation of the “capture radius” under varying conditions. Conclusion: The simulation allows a shift in perspective that is paramount in attempting to communicate the scale and dynamics of intracellular protein cascade mechanics. This work has allowed researchers to more fully understand the parameters involved in intracellular electrodynamics, such as shielding anion concentration and protein charge. As these effects are still far below the spatial resolution of currently available measurement technology this

  19. Nucleocytoplasmic shuttling mediates the dynamic maintenance of nuclear Dorsal levels during Drosophila embryogenesis

    DEFF Research Database (Denmark)

    DeLotto, Robert; DeLotto, Yvonne; Steward, Ruth

    2007-01-01

    , including nuclei on the dorsal side. Nuclear export is blocked by leptomycin B, a potent inhibitor of Exportin 1 (CRM1)-mediated nuclear export. We have developed a novel in vivo assay revealing the presence of a functional leucine-rich nuclear export signal within the carboxyterminal 44 amino acids...

  20. DMPD: Nuclear receptors in macrophages: a link between metabolism and inflammation. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 18022390 Nuclear receptors in macrophages: a link between metabolism and inflammati...on. Szanto A, Roszer T. FEBS Lett. 2008 Jan 9;582(1):106-16. Epub 2007 Nov 20. (.png) (.svg) (.html) (.csml) Show Nuclear... receptors in macrophages: a link between metabolism and inflammation. PubmedID 18022390 Title Nuclear

  1. DMPD: Nuclear receptor signaling in macrophages. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 14698033 Nuclear receptor signaling in macrophages. Valledor AF, Ricote M. Biochem ...Pharmacol. 2004 Jan 15;67(2):201-12. (.png) (.svg) (.html) (.csml) Show Nuclear receptor signaling in macrop...hages. PubmedID 14698033 Title Nuclear receptor signaling in macrophages. Authors Valledor AF, Ricote M. Pub

  2. Nuclear magnetic resonance structure and dynamics of the response regulator Sma0114 from Sinorhizobium meliloti.

    Science.gov (United States)

    Sheftic, Sarah R; Garcia, Preston P; White, Emma; Robinson, Victoria L; Gage, Daniel J; Alexandrescu, Andrei T

    2012-09-04

    Receiver domains control intracellular responses triggered by signal transduction in bacterial two-component systems. Here, we report the solution nuclear magnetic resonance structure and dynamics of Sma0114 from the bacterium Sinorhizobium meliloti, the first such characterization of a receiver domain from the HWE-kinase family of two-component systems. The structure of Sma0114 adopts a prototypical α(5)/β(5) Rossman fold but has features that set it apart from other receiver domains. The fourth β-strand of Sma0114 houses a PFxFATGY sequence motif, common to many HWE-kinase-associated receiver domains. This sequence motif in Sma0114 may substitute for the conserved Y-T coupling mechanism, which propagates conformational transitions in the 455 (α4-β5-α5) faces of receiver domains, to prime them for binding downstream effectors once they become activated by phosphorylation. In addition, the fourth α-helix of the consensus 455 face in Sma0114 is replaced with a segment that shows high flexibility on the pico- to nanosecond time scale by (15)N relaxation data. Secondary structure prediction analysis suggests that the absence of helix α4 may be a conserved property of the HWE-kinase-associated family of receiver domains to which Sma0114 belongs. In spite of these differences, Sma0114 has a conserved active site, binds divalent metal ions such as Mg(2+) and Ca(2+) that are required for phosphorylation, and exhibits micro- to millisecond active-site dynamics similar to those of other receiver domains. Taken together, our results suggest that Sma0114 has a conserved active site but differs from typical receiver domains in the structure of the 455 face that is used to effect signal transduction following activation.

  3. A dynamic food-chain model and program for predicting the consequences of nuclear accident

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    A dynamic food-chain model and program, DYFOM-95, forpredicting the radiological consequences of nuclear accident hasbeen developed, which is not only suitable to the West food-chainbut also to Chinese food chain. The following processes, caused byaccident release which will make an impact on radionuclideconcentration in the edible parts of vegetable are considered: dryand wet deposition interception and initial retention,translocation, percolation, root uptake and tillage. Activityintake rate of animals, effects of processing and activity intakeof human through ingestion pathway are also considered incalculations. The effects of leaf area index LAI of vegetable areconsidered in dry deposition model. A method for calculating thecontribution of rain with different period and different intensityto total wet deposition is established. The program contains 1 maincode and 5 sub-codes to calculate dry and wet deposition on surfaceof vegetable and soil, translocation of nuclides in vegetable,nuclide concentration in the edible parts of vegetable and inanimal products and activity intake of human and so on.

  4. The dynamism of PABPN1 nuclear inclusions during the cell cycle.

    Science.gov (United States)

    Marie-Josée Sasseville, A; Caron, Antoine W; Bourget, Lucie; Klein, Arnaud F; Dicaire, Marie-Josée; Rouleau, Guy A; Massie, Bernard; Langelier, Yves; Brais, Bernard

    2006-09-01

    Oculopharyngeal muscular dystrophy (OPMD) is caused by expansion of a (GCN)10 to a (GCN)11-17 repeat coding for a polyalanine domain at the N-terminal part of poly(A) binding protein nuclear 1 (PABPN1). OPMD is characterized by the presence of intranuclear inclusions (INIs) in skeletal muscle fibers of patients. The formation of GFP-b13AlaPABPN1 INIs and their fate through the cell cycle were followed by time-lapse imaging. Our observations demonstrated that the GFP-b13AlaPABPN1 INIs are dynamic structures that can disassemble during mitosis. However, their presence in cells occasionally led to apoptosis. The length of the polyalanine tail or the overexpression of PABPN1 did not significantly affect the percentage of soluble PABPN1 in vitro. Moreover, overexpression of either the wild type (wt) or mutant (mut) forms of PABPN1 slowed down the cell proliferation. The slowing down of proliferation together with the occasional occurrence of apoptosis could contribute in vivo to the late onset of this disease.

  5. Molecular dynamics and composition of crude oil by low-field nuclear magnetic resonance.

    Science.gov (United States)

    Jia, Zijian; Xiao, Lizhi; Wang, Zhizhan; Liao, Guangzhi; Zhang, Yan; Liang, Can

    2016-08-01

    Nuclear magnetic resonance (NMR) techniques are widely used to identify pure substances and probe protein dynamics. Oil is a complex mixture composed of hydrocarbons, which have a wide range of molecular size distribution. Previous work show that empirical correlations of relaxation times and diffusion coefficients were found for simple alkane mixtures, and also the shape of the relaxation and diffusion distribution functions are related to the composition of the fluids. The 2D NMR is a promising qualitative evaluation method for oil composition. But uncertainty in the interpretation of crude oil indicated further study was required. In this research, the effect of each composition on relaxation distribution functions is analyzed in detail. We also suggest a new method for prediction of the rotational correlation time distribution of crude oil molecules using low field NMR (LF-NMR) relaxation time distributions. A set of down-hole NMR fluid analysis system is independently designed and developed for fluid measurement. We illustrate this with relaxation-relaxation correlation experiments and rotational correlation time distributions on a series of hydrocarbon mixtures that employ our laboratory-designed downhole NMR fluid analyzer. The LF-NMR is a useful tool for detecting oil composition and monitoring oil property changes. Copyright © 2016 John Wiley & Sons, Ltd.

  6. Dynamical origin of nuclear multifragmentation; Origine dynamique de la multifragmentation nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Tirel, O. [Caen Univ., 14 (France)

    1998-12-01

    The study of the peripheral and semi-peripheral collisions in the reaction Xe+Sn at 50 A.MeV has lead to the identification of the role of out-of-equilibrium aspects in the production of intermediate mass fragments (IMF). First, it is shown that the experimental observations are incompatible with a model in which a very hot layer of matter is primarily responsible for the production of IMF at intermediate velocity. Next, the same data are compared with a calculation using the quantum molecular dynamics approach (QMD). the quality of agreement with the predictions of this model allows to draw conclusions concerning the production mechanism of fragments. The IMF originate from region that is intermediate between the projectile and the target. It is furthermore shown that this region is not in thermal equilibrium, that the fragments are pre-formed and that their velocity and composition strongly depend on the initial conditions of the reaction. The quasi-projectile and the quasi-target, on the other hand, are only mildly influenced by the collision and their excitation energies are estimated to be below the limit at which multifragmentation will take place. In parallel, an analysis is carried out which correlates he multiplicity of the IMF with the violence of the collision. This shows that a proper analysis of a process as complex as nuclear multifragmentation must simultaneously involve kinetic variables (velocity, energy,...) as well as static ones (multiplicity. charge distribution,...). (author)

  7. Increasing the energy dynamic range of solid-state nuclear track detectors using multiple surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Zylstra, A. B.; Rinderknecht, H. G.; Sinenian, N.; Rosenberg, M. J.; Manuel, M.; Seguin, F. H.; Casey, D. T.; Frenje, J. A.; Li, C. K.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge,Massachusetts 02139 (United States)

    2011-08-15

    Solid-state nuclear track detectors, such as CR-39, are widely used in physics and in many inertial confinement fusion (ICF) experiments. In the ICF experiments, the particles of interest, such as D{sup 3}He-protons, have ranges of order of the detector thickness. In this case, the dynamic range of the detector can be extended by recording data on both the front and back sides of the detector. Higher energy particles which are undetectable on the front surface can then be measured on the back of the detector. Studies of track formation under the conditions on the front and back of the detector reveal significant differences. Distinct front and back energy calibrations of CR-39 are therefore necessary and are presented for protons. Utilizing multiple surfaces with additional calibrations can extend the range of detectable energies on a single piece of CR-39 by up to 7-8 MeV. The track formation process is explored with a Monte Carlo code, which shows that the track formation difference between front and back is due to the non-uniform ion energy deposition in matter.

  8. Quantitative dynamic nuclear polarization-NMR on blood plasma for assays of drug metabolism.

    Science.gov (United States)

    Lerche, Mathilde H; Meier, Sebastian; Jensen, Pernille R; Hustvedt, Svein-Olaf; Karlsson, Magnus; Duus, Jens Ø; Ardenkjaer-Larsen, Jan H

    2011-01-01

    Analytical platforms for the fast detection, identification and quantification of circulating drugs with a narrow therapeutic range are vital in clinical pharmacology. As a result of low drug concentrations, analytical tools need to provide high sensitivity and specificity. Dynamic nuclear polarization-NMR (DNP-NMR) in the form of the hyperpolarization-dissolution method should afford the sensitivity and spectral resolution for the direct detection and quantification of numerous isotopically labeled circulating drugs and their metabolites in single liquid-state NMR transients. This study explores the capability of quantitative in vitro DNP-NMR to assay drug metabolites in blood plasma. The lower limit of detection for the anti-epileptic drug (13)C-carbamazepine and its pharmacologically active metabolite (13)C-carbamazepine-10,11-epoxide is 0.08 µg/mL in rabbit blood plasma analyzed by single-scan (13)C DNP-NMR. An internal standard is used for the accurate quantification of drug and metabolite. Comparison of quantitative DNP-NMR data with an established analytical method (liquid chromatography-mass spectrometry) yields a Pearson correlation coefficient r of 0.99. Notably, all DNP-NMR determinations were performed without analyte derivatization or sample purification other than plasma protein precipitation. Quantitative DNP-NMR is an emerging methodology which requires little sample preparation and yields quantitative data with high sensitivity for therapeutic drug monitoring.

  9. A Dynamical Model for Gas Flows, Star Formation, and Nuclear Winds in Galactic Centres

    CERN Document Server

    Krumholz., Mark R; Crocker, Roland M

    2016-01-01

    We present a dynamical model for gas transport, star formation, and winds in the nuclear regions of galaxies, focusing on the Milky Way's Central Molecular Zone (CMZ). In our model angular momentum and mass are transported by a combination of gravitational and bar-driven acoustic instabilities. In gravitationally-unstable regions the gas can form stars, and the resulting feedback drives both turbulence and a wind that ejects mass from the CMZ. We show that the CMZ is in a quasi-steady state where mass deposited at large radii by the bar is transported inward to a star-forming, ring-shaped region at $\\sim 100$ pc from the Galactic Centre, where the shear reaches a minimum. This ring undergoes episodic starbursts, with bursts lasting $\\sim 5-10$ Myr occurring at $\\sim 20-40$ Myr intervals. During quiescence the gas in the ring is not fully cleared, but is driven out of a self-gravitating state by the momentum injected by expanding supernova remnants. Starbursts also drive a wind off the star-forming ring, with ...

  10. Towards a nonequilibrium Green's function description of nuclear reactions: one-dimensional mean-field dynamics

    CERN Document Server

    Rios, Arnau; Buchler, Mark; Danielewicz, Pawel

    2010-01-01

    Nonequilibrium Green's function methods allow for an intrinsically consistent description of the evolution of quantal many-body body systems, with inclusion of different types of correlations. In this paper, we focus on the practical developments needed to build a Green's function methodology for nuclear reactions. We start out by considering symmetric collisions of slabs in one dimension within the mean-field approximation. We concentrate on two issues of importance for actual reaction simulations. First, the preparation of the initial state within the same methodology as for the reaction dynamics is demonstrated by an adiabatic switching on of the mean-field interaction, which leads to the mean-field ground state. Second, the importance of the Green's function matrix-elements far away from the spatial diagonal is analyzed by a suitable suppression process that does not significantly affect the evolution of the elements close to the diagonal. The relative lack of importance of the far-away elements is tied t...

  11. Assessment of water hammer effects on boiling water nuclear reactor core dynamics

    Directory of Open Access Journals (Sweden)

    Bousbia-Salah Anis

    2007-01-01

    Full Text Available Complex phenomena, as water hammer transients, occurring in nuclear power plants are still not very well investigated by the current best estimate computational tools. Within this frame work, a rapid positive reactivity addition into the core generated by a water hammer transient is considered. The numerical simulation of such phenomena was carried out using the coupled RELAP5/PARCS code. An over all data comparison shows good agreement between the calculated and measured core pressure wave trends. However, the predicted power response during the excursion phase did not correctly match the experimental tendency. Because of this, sensitivity studies have been carried out in order to identify the most influential parameters that govern the dynamics of the power excursion. After investigating the pressure wave amplitude and the void feed back responses, it was found that the disagreement between the calculated and measured data occurs mainly due to the RELAP5 low void condensation rate which seems to be questionable during rapid transients. .

  12. Thermosetting polymer for dynamic nuclear polarization: Solidification of an epoxy resin mixture including TEMPO

    Energy Technology Data Exchange (ETDEWEB)

    Noda, Yohei, E-mail: noda.yohei@jaea.go.jp [Quantum Beam Science Centre, Sector of Nuclear Science Research, Japan Atomic Energy Agency, Shirakata-Shirane, Tokai, Ibaraki 319-1195 (Japan); Kumada, Takayuki [Quantum Beam Science Centre, Sector of Nuclear Science Research, Kansai Photon Science Institute, Japan Atomic Energy Agency, Kizugawa, Kyoto 619-0215 (Japan); Yamaguchi, Daisuke; Shamoto, Shin-ichi [Quantum Beam Science Centre, Sector of Nuclear Science Research, Japan Atomic Energy Agency, Shirakata-Shirane, Tokai, Ibaraki 319-1195 (Japan)

    2015-03-11

    We investigated the dynamic nuclear polarization (DNP) of typical thermosetting polymers (two-component type epoxy resins; Araldite{sup ®} Standard or Araldite{sup ®} Rapid) doped with a (2,2,6,6-tetramethylpiperidine-1-yl)oxy (TEMPO) radical. The doping process was developed by carefully considering the decomposition of TEMPO during the solidification of the epoxy resin. The TEMPO electron spin in each two-component paste decayed slowly, which was favorable for our study. Furthermore, despite the dissolved TEMPO, the mixture of the two-component paste successfully solidified. With the resulting TEMPO-doped epoxy-resin samples, DNP experiments at 1.2 K and 3.35 T indicated a magnitude of a proton-spin polarization up to 39%. This polarization is similar to that (35%) obtained for TEMPO-doped polystyrene (PS), which is often used as a standard sample for DNP. To combine this solidification of TEMPO-including mixture with a resin-casting technique enables a creation of polymeric target materials with a precise and complex structure.

  13. Non-Gaussian fluctuations and non-Markovian effects in the nuclear fusion process: Langevin dynamics emerging from quantum molecular dynamics simulations.

    Science.gov (United States)

    Wen, Kai; Sakata, Fumihiko; Li, Zhu-Xia; Wu, Xi-Zhen; Zhang, Ying-Xun; Zhou, Shan-Gui

    2013-07-05

    Macroscopic parameters as well as precise information on the random force characterizing the Langevin-type description of the nuclear fusion process around the Coulomb barrier are extracted from the microscopic dynamics of individual nucleons by exploiting the numerical simulation of the improved quantum molecular dynamics. It turns out that the dissipation dynamics of the relative motion between two fusing nuclei is caused by a non-Gaussian distribution of the random force. We find that the friction coefficient as well as the time correlation function of the random force takes particularly large values in a region a little bit inside of the Coulomb barrier. A clear non-Markovian effect is observed in the time correlation function of the random force. It is further shown that an emergent dynamics of the fusion process can be described by the generalized Langevin equation with memory effects by appropriately incorporating the microscopic information of individual nucleons through the random force and its time correlation function.

  14. Bidirectional extracellular matrix signaling during tissue morphogenesis

    Science.gov (United States)

    Gjorevski, Nikolce; Nelson, Celeste M.

    2009-01-01

    Normal tissue development and function are regulated by the interplay between cells and their surrounding extracellular matrix (ECM). The ECM provides biochemical and mechanical contextual information that is conveyed from the cell membrane through the cytoskeleton to the nucleus to direct cell phenotype. Cells, in turn, remodel the ECM and thereby sculpt their local microenvironment. Here we review the mechanisms by which cells interact with, respond to, and influence the ECM, with particular emphasis placed on the role of this bidirectional communication during tissue morphogenesis. We also discuss the implications for successful engineering of functional tissues ex vivo. PMID:19896886

  15. Orthogonal schemes for bidirectional associative memories.

    Science.gov (United States)

    Haryono, H; Sadananda, R; Phien, H N

    1997-01-01

    Two issues are addressed in this paper. Firstly, it investigates some important properties of bidirectional associative memories (BAM) and proposes an improved capacity estimate. Those properties are the encoding form of the input pattern pairs as sell as their decoding, the orthogonality of the pattern pairs, the similarity of associated patterns, and the density of the pattern pairs. Secondly, it proposes an implementation approach to improve the storage capacity. The approach embraces three proposed methods, i.e., the bipolar-orthogonal augmentation, the set partition, and the combined method. Along with those methods is the construction of the set of bipolar orthogonal patterns.

  16. Bidirectionality Between Sleep Symptoms and Cores Depressive Symptoms and Their Long-Term Course in Major Depression

    NARCIS (Netherlands)

    Bouwmans, Mara E J; Conradi, Henk Jan; Bos, Elisabeth H; Oldehinkel, Albertine J; de Jonge, Peter

    2016-01-01

    OBJECTIVES: To investigate the bidirectional dynamic relationship between sleep symptoms and core depressive symptoms and to identify subgroups differing with respect to their course. METHODS: The weekly state of depressive symptoms in depressed primary care patients (N = 267) was assessed retrospec

  17. Interfacial Ca2+ environments in nanocrystalline apatites revealed by dynamic nuclear polarization enhanced 43Ca NMR spectroscopy

    Science.gov (United States)

    Lee, Daniel; Leroy, César; Crevant, Charlène; Bonhomme-Coury, Laure; Babonneau, Florence; Laurencin, Danielle; Bonhomme, Christian; de Paëpe, Gaël

    2017-01-01

    The interfaces within bones, teeth and other hybrid biomaterials are of paramount importance but remain particularly difficult to characterize at the molecular level because both sensitive and selective techniques are mandatory. Here, it is demonstrated that unprecedented insights into calcium environments, for example the differentiation of surface and core species of hydroxyapatite nanoparticles, can be obtained using solid-state NMR, when combined with dynamic nuclear polarization. Although calcium represents an ideal NMR target here (and de facto for a large variety of calcium-derived materials), its stable NMR-active isotope, calcium-43, is a highly unreceptive probe. Using the sensitivity gains from dynamic nuclear polarization, not only could calcium-43 NMR spectra be obtained easily, but natural isotopic abundance 2D correlation experiments could be recorded for calcium-43 in short experimental time. This opens perspectives for the detailed study of interfaces in nanostructured materials of the highest biological interest as well as calcium-based nanosystems in general.

  18. Observation of strongly forbidden solid effect dynamic nuclear polarization transitions via electron-electron double resonance detected NMR.

    Science.gov (United States)

    Smith, Albert A; Corzilius, Björn; Haze, Olesya; Swager, Timothy M; Griffin, Robert G

    2013-12-01

    We present electron paramagnetic resonance experiments for which solid effect dynamic nuclear polarization transitions were observed indirectly via polarization loss on the electron. This use of indirect observation allows characterization of the dynamic nuclear polarization (DNP) process close to the electron. Frequency profiles of the electron-detected solid effect obtained using trityl radical showed intense saturation of the electron at the usual solid effect condition, which involves a single electron and nucleus. However, higher order solid effect transitions involving two, three, or four nuclei were also observed with surprising intensity, although these transitions did not lead to bulk nuclear polarization--suggesting that higher order transitions are important primarily in the transfer of polarization to nuclei nearby the electron. Similar results were obtained for the SA-BDPA radical where strong electron-nuclear couplings produced splittings in the spectrum of the indirectly observed solid effect conditions. Observation of high order solid effect transitions supports recent studies of the solid effect, and suggests that a multi-spin solid effect mechanism may play a major role in polarization transfer via DNP.

  19. Observation of strongly forbidden solid effect dynamic nuclear polarization transitions via electron-electron double resonance detected NMR

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Albert A.; Corzilius, Björn; Haze, Olesya; Swager, Timothy M.; Griffin, Robert G., E-mail: rgg@mit.edu [Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2013-12-07

    We present electron paramagnetic resonance experiments for which solid effect dynamic nuclear polarization transitions were observed indirectly via polarization loss on the electron. This use of indirect observation allows characterization of the dynamic nuclear polarization (DNP) process close to the electron. Frequency profiles of the electron-detected solid effect obtained using trityl radical showed intense saturation of the electron at the usual solid effect condition, which involves a single electron and nucleus. However, higher order solid effect transitions involving two, three, or four nuclei were also observed with surprising intensity, although these transitions did not lead to bulk nuclear polarization—suggesting that higher order transitions are important primarily in the transfer of polarization to nuclei nearby the electron. Similar results were obtained for the SA-BDPA radical where strong electron-nuclear couplings produced splittings in the spectrum of the indirectly observed solid effect conditions. Observation of high order solid effect transitions supports recent studies of the solid effect, and suggests that a multi-spin solid effect mechanism may play a major role in polarization transfer via DNP.

  20. Homogenisation method for the dynamic analysis of a complete nuclear steam generator with fluid-structure interaction

    Energy Technology Data Exchange (ETDEWEB)

    Sigrist, Jean-Francois [DCNS Propulsion-DI/STS, 44620 La Montagne (France)], E-mail: jean-francois.sigrist@dcn.fr; Broc, Daniel [CEA Saclay-DEMT/EMSI, 91191 Gif-sur-Yvette (France)

    2008-09-15

    The present paper deals with the dynamic analysis of a steam generator tube bundle with fluid-structure interaction modelling. As the coupled fluid-structure problem involves a huge number of degrees of freedom to account for the tube displacements and the fluid pressure evolutions, classical coupled method cannot be applied for industrial studies. In the present case, the three-dimensional fluid-structure problem is solved with an homogenisation method, which has been previously exposed and successfully validated for FSI modelling in a nuclear reactor [Sigrist, J.F., Broc, D., 2007a. Homogenisation method for the modal analysis of a nuclear reactor with internal structures modelling and fluid-structure interaction coupling. Nuclear Engineering and Design 237, 431-440]. Formulation of the homogenisation method for general two- and three-dimensional cases is exposed in the paper. Application to a simplified, however representative, model of an actual industrial nuclear component (steam generator) is proposed. The problem modelling, which includes tube bundle, primary and secondary fluids and pressure vessel, is performed with an engineering finite element code in which the homogenisation technique has been implemented. From the practical point of view, the analysis highlights the major fluid-structure interaction effects on the dynamic behaviour of the steam generator; from the theoretical point of view, the study demonstrates the efficiency of the homogenisation method for periodic fluid-structure problems modelling in industrial configurations.

  1. 1H-NMR and photochemically-induced dynamic nuclear polarization studies on bovine pancreatic phospholipase A2.

    Science.gov (United States)

    Egmond, M R; Slotboom, A J; De Haas, G H; Dijkstra, K; Kaptein, R

    1980-06-26

    Proton-NMR resonances of trytophan 3 and tyrosine 69 in bovine pancreatic phospholipase A2, its pro-enzyme and in Ala1-transaminated protein were assigned using photochemically-induced dynamic nuclear polarization (photo-CIDNP) as such or in combination with spin-echo measurements. In addition assignments were made by suppression of cross-relaxation effects using short (0.1 s) high-power laser pulses.

  2. Emp is a component of the nuclear matrix of mammalian cells and undergoes dynamic rearrangements during cell division.

    Science.gov (United States)

    Bala, Shashi; Kumar, Ajay; Soni, Shivani; Sinha, Sudha; Hanspal, Manjit

    2006-04-21

    Emp, originally detected in erythroblastic islands, is expressed in numerous cell types and tissues suggesting a functionality not limited to hematopoiesis. To study the function of Emp in non-hematopoietic cells, an epitope-tagged recombinant human Emp was expressed in HEK cells. Preliminary studies revealed that Emp partitioned into both the nuclear and Triton X-100-insoluble cytoskeletal fractions in approximately a 4:1 ratio. In this study, we report investigations of Emp in the nucleus. Sequential extractions of interphase nuclei showed that recombinant Emp was present predominantly in the nuclear matrix. Immunofluorescence microscopy showed that Emp was present in typical nuclear speckles enriched with the spliceosome assembly factor SC35 and partially co-localized with actin staining. Coimmunoprecipitation and GST-pull-down assays confirmed the apparent close association of Emp with nuclear actin. During mitosis, Emp was detected at the mitotic spindle/spindle poles, as well as in the contractile ring during cytokinesis. These results suggest that Emp undergoes dynamic rearrangements within the nuclear architecture that are correlated with cell division.

  3. Evaluation of a regional air-quality model with bidirectional NH3 exchange coupled to an agroecosystem model

    Directory of Open Access Journals (Sweden)

    J. O. Bash

    2013-03-01

    Full Text Available Atmospheric ammonia (NH3 is the primary atmospheric base and an important precursor for inorganic particulate matter and when deposited NH3 contributes to surface water eutrophication, soil acidification and decline in species biodiversity. Flux measurements indicate that the air–surface exchange of NH3 is bidirectional. However, the effects of bidirectional exchange, soil biogeochemistry and human activity are not parameterized in air quality models. The US Environmental Protection Agency's (EPA Community Multiscale Air-Quality (CMAQ model with bidirectional NH3 exchange has been coupled with the United States Department of Agriculture's (USDA Environmental Policy Integrated Climate (EPIC agroecosystem model. The coupled CMAQ-EPIC model relies on EPIC fertilization timing, rate and composition while CMAQ models the soil ammonium (NH4+ pool by conserving the ammonium mass due to fertilization, evasion, deposition, and nitrification processes. This mechanistically coupled modeling system reduced the biases and error in NHx (NH3 + NH4+ wet deposition and in ambient aerosol concentrations in an annual 2002 Continental US (CONUS domain simulation when compared to a 2002 annual simulation of CMAQ without bidirectional exchange. Fertilizer emissions estimated in CMAQ 5.0 with bidirectional exchange exhibits markedly different seasonal dynamics than the US EPA's National Emissions Inventory (NEI, with lower emissions in the spring and fall and higher emissions in July.

  4. Evaluation of a regional air-quality model with bidirectional NH3 exchange coupled to an agroecosystem model

    Science.gov (United States)

    Bash, J. O.; Cooter, E. J.; Dennis, R. L.; Walker, J. T.; Pleim, J. E.

    2013-03-01

    Atmospheric ammonia (NH3) is the primary atmospheric base and an important precursor for inorganic particulate matter and when deposited NH3 contributes to surface water eutrophication, soil acidification and decline in species biodiversity. Flux measurements indicate that the air-surface exchange of NH3 is bidirectional. However, the effects of bidirectional exchange, soil biogeochemistry and human activity are not parameterized in air quality models. The US Environmental Protection Agency's (EPA) Community Multiscale Air-Quality (CMAQ) model with bidirectional NH3 exchange has been coupled with the United States Department of Agriculture's (USDA) Environmental Policy Integrated Climate (EPIC) agroecosystem model. The coupled CMAQ-EPIC model relies on EPIC fertilization timing, rate and composition while CMAQ models the soil ammonium (NH4+) pool by conserving the ammonium mass due to fertilization, evasion, deposition, and nitrification processes. This mechanistically coupled modeling system reduced the biases and error in NHx (NH3 + NH4+) wet deposition and in ambient aerosol concentrations in an annual 2002 Continental US (CONUS) domain simulation when compared to a 2002 annual simulation of CMAQ without bidirectional exchange. Fertilizer emissions estimated in CMAQ 5.0 with bidirectional exchange exhibits markedly different seasonal dynamics than the US EPA's National Emissions Inventory (NEI), with lower emissions in the spring and fall and higher emissions in July.

  5. Dynamic Nuclear Polarization enhanced NMR at 187 GHz/284 MHz using an Extended Interaction Klystron amplifier

    Science.gov (United States)

    Kemp, Thomas F.; Dannatt, Hugh R. W.; Barrow, Nathan S.; Watts, Anthony; Brown, Steven P.; Newton, Mark E.; Dupree, Ray

    2016-04-01

    A Dynamic Nuclear Polarisation (DNP) enhanced solid-state Magic Angle Spinning (MAS) NMR spectrometer which uses a 187 GHz (corresponding to 1H NMR frequency of 284 MHz) Extended Interaction Klystron (EIK) amplifier as the microwave source is briefly described. Its performance is demonstrated for a biomolecule (bacteriorhodopsin), a pharmaceutical, and surface functionalised silica. The EIK is very compact and easily incorporated into an existing spectrometer. The bandwidth of the amplifier is sufficient that it obviates the need for a sweepable magnetic field, once set, for all commonly used radicals. The variable power (CW or pulsed) output from the EIK is transmitted to the DNP-NMR probe using a quasi-optic system with a high power isolator and a corrugated waveguide which feeds the microwaves into the DNP-NMR probe. Curved mirrors inside the probe project the microwaves down the axis of the MAS rotor, giving a very efficient system such that maximum DNP enhancement is achieved with less than 3 W output from the microwave source. The DNP-NMR probe operates with a sample temperature down to 90 K whilst spinning at 8 kHz. Significant enhancements, in excess of 100 for bacteriorhodopsin in purple membrane (bR in PM), are shown along with spectra which are enhanced by ≈25 with respect to room temperature, for both the pharmaceutical furosemide and surface functionalised silica. These enhancements allow hitherto prohibitively time consuming experiments to be undertaken. The power at which the DNP enhancement in bR in PM saturates does not change significantly between 90 K and 170 K even though the enhancement drops by a factor of ≈11. As the DNP build up time decreases by a factor 3 over this temperature range, the reduction in T1n is presumably a significant contribution to the drop in enhancement.

  6. Personalized recommendation based on heat bidirectional transfer

    Science.gov (United States)

    Ma, Wenping; Feng, Xiang; Wang, Shanfeng; Gong, Maoguo

    2016-02-01

    Personalized recommendation has become an increasing popular research topic, which aims to find future likes and interests based on users' past preferences. Traditional recommendation algorithms pay more attention to forecast accuracy by calculating first-order relevance, while ignore the importance of diversity and novelty that provide comfortable experiences for customers. There are some levels of contradictions between these three metrics, so an algorithm based on bidirectional transfer is proposed in this paper to solve this dilemma. In this paper, we agree that an object that is associated with history records or has been purchased by similar users should be introduced to the specified user and recommendation approach based on heat bidirectional transfer is proposed. Compared with the state-of-the-art approaches based on bipartite network, experiments on two benchmark data sets, Movielens and Netflix, demonstrate that our algorithm has better performance on accuracy, diversity and novelty. Moreover, this method does better in exploiting long-tail commodities and cold-start problem.

  7. [Novel bidirectional promoter from human genome].

    Science.gov (United States)

    Orekhova, A S; Sverdlova, P S; Spirin, P V; Leonova, O G; Popenko, V I; Prasolov, V S; Rubtsov, P M

    2011-01-01

    In human and other mammalian genomes a number of closely linked gene pairs transcribed in opposite directions are found. According to bioinformatic analysis up to 10% of human genes are arranged in this way. In present work the fragment of human genome was cloned that separates genes localized at 2p13.1 and oriented "head-to-head", coding for hypothetical proteins with unknown functions--CCDC (Coiled Coil Domain Containing) 142 and TTC (TetraTricopeptide repeat Containing) 31. Intergenic CCDC142-TTC31 region overlaps with CpG-island and contains a number of potential binding sites for transcription factors. This fragment functions as bidirectional promoter in the system ofluciferase reporter gene expression upon transfection of human embryonic kidney (HEK293) cells. The vectors containing genes of two fluorescent proteins--green (EGFP) and red (DsRed2) in opposite orientations separated by the fragment of CCDC142-TTC31 intergenic region were constructed. In HEK293 cells transfected with these vectors simultaneous expression of two fluorescent proteins is observed. Truncated versions of intergenic region were obtained and their promoter activity measured. Minimal promoter fragment contains elements Inr, BRE, DPE characteristic for TATA-less promoters. Thus, from the human genome the novel bidirectional promoter was cloned that can be used for simultaneous constitutive expression of two genes in human cells.

  8. The Dynamic Monte Carlo Method for Transient Analysis of Nuclear Reactors

    NARCIS (Netherlands)

    Sjenitzer, B.L.

    2013-01-01

    In this thesis a new method for the analysis of power transients in a nuclear reactor is developed, which is more accurate than the present state-of-the-art methods. Transient analysis is important tool when designing nuclear reactors, since they predict the behaviour of a reactor during changing co

  9. The nuclear industry is about to begin a new dynamic. Interview with Luis Echavarri

    Energy Technology Data Exchange (ETDEWEB)

    Mitev, Lubomir [NucNet, Brussels (Belgium)

    2014-05-15

    The nuclear industry has changed significantly in the 17 years since Luis Echavarri became director-general of the Organisation for Economic Development and Cooperation's (OECD) Paris-based Nuclear Energy Agency (NEA). As he approaches retirement, Mr Echavarri speaks to NucNet about the priorities for the industry as it enters the post-Fukushima era. (orig.)

  10. Coherent-states dynamics of the H + + HF reaction at ELab = 30 eV: A complete electron nuclear dynamics investigation

    Science.gov (United States)

    Maiti, Buddhadev; Sadeghi, Raymond; Austin, Anthony; Morales, Jorge A.

    2007-11-01

    Results of a complete investigation of the H + + HF reaction at ELab = 30 eV with the electron nuclear dynamics (END) and the coherent-states dynamics (CSD) theories are herein presented. Current END-CSD methodology employs frozen Gaussian wave packet in the semiclassical limit of ℏ → 0 for the nuclei, and a single-determinantal Thouless coherent state (CS) for the electrons. The simulated 400 CS trajectories from five independent HF target orientations provide a complete description of the reactive processes in this system, including: non-charge-transfer scattering (NCTS), charge-transfer scattering (CTS), hydrogen fluoride dissociation (H-F D), and hydrogen rearrangement (HR). Several aspects of the reactions dynamics, such as mechanistic details and rainbow angles effects, are discussed. Differential and integral cross sections are evaluated via a novel CS formulation of those properties in conjunction with semiclassical techniques. The calculated total differential cross section shows an excellent agreement with available experimental results.

  11. Ultrasensitive PCR and real-time detection from human genomic samples using a bidirectional flow microreactor.

    Science.gov (United States)

    Chen, Lin; West, Jonathan; Auroux, Pierre-Alain; Manz, Andreas; Day, Philip J R

    2007-12-01

    In this paper we present a reliable bidirectional flow DNA amplification microreactor for processing real-world genomic samples. This system shares the low-power thermal responsiveness of a continuous flow reactor with the low surface area to volume ratio character of stationary reactors for reducing surface inhibitory effects. Silanization with dimethyldichlorosilane in combination with dynamic surface passivation was used to enhance PCR compatibility and enable efficient amplification. For real-time fragment amplification monitoring we have implemented an epimodal fluorescent detection capability. The passivated bidirectional flow system was ultrasensitive, achieving an RNase P gene detection limit of 24 human genome copies with a reaction efficiency of 77%. This starts to rival the performance of a conventional real-time PCR instrument with a reaction efficiency of 93% and revitalizes flow-through PCR as a viable component of lab on a chip DNA analysis formats.

  12. A reference standard for bidirectional reflection distribution function and bidirectional transmission distribution function measurement

    Science.gov (United States)

    Witherow, William K. (Inventor)

    1988-01-01

    A Lambertian reference standard for uniformly scattering a beam of light is constructed of a plate having a planar surface with a layer of glue disposed on the surface. An evenly packed layer of monodisperse spheres is set in the layer, and when the standard is used for bi-directional (BRDF) measurements, the spheres are coated with a layer of highly relective substance, such as gold or silver. When the standard is used for bi-directional transmittance distribution function (BTDF) measurements, the spheres are of a transparent material and are provided with a roughened surface, as by acid etching. In this case, the layer of glue is an optical cement, and the plate is of glass, with the spheres, the layer, and the plate all possessing a similar refractive index.

  13. Probing in Space and Time the Nuclear Motion Driven by Nonequilibrium Electronic Dynamics in Ultrafast Pumped N2.

    Science.gov (United States)

    Ajay, J; Šmydke, J; Remacle, F; Levine, R D

    2016-05-19

    An ultrafast electronic excitation of N2 in the vacuum ultraviolet creates a nonstationary coherent linear superposition of interacting valence and Rydberg states resulting in a net oscillating dipole moment. There is therefore a linear response to an electrical field that can be queried by varying the time delay between the pump and a second optical probe pulse. Both the pump and probe pulses are included in our computation as part of the Hamiltonian, and the time-dependent wave function for both electronic and nuclear dynamics is computed using a grid representation for the internuclear coordinate. Even on an ultrafast time scale there are several processes that can be discerned beyond the expected coherence oscillations. In particular, the coupling between the excited valence and Rydberg states of the same symmetry is very evident and can be directly probed by varying the delay between pulse and probe. For quite a number of vibrations the nuclear motion does not dephase the electronic disequilibrium. However, the nuclear motion does modulate the dipolar response by taking the wave packet in and out of the Franck-Condon region and by its strong influence on the coupling of the Rydberg and valence states. A distinct isotope effect arises from the dependence of the interstate coupling on the nuclear mass.

  14. Three-integral multi-component dynamical models and simulations of the nuclear star cluster in NGC 4244

    CERN Document Server

    De Lorenzi, F; Debattista, V P; Seth, A C; Gerhard, O

    2012-01-01

    Adaptive optics observations of the flattened nuclear star cluster in the nearby edge-on spiral galaxy NGC 4244 using the Gemini Near-Infrared Integral Field Spectrograph (NIFS) have revealed clear rotation. Using these kinematics plus 2MASS photometry we construct a series of axisymmetric two-component particle dynamical models with our improved version of NMAGIC, a flexible Chi^2-made-to-measure code. The models consist of a nuclear cluster disc embedded within a spheroidal particle population. We find a mass for the nuclear star cluster of M=1.6^+0.5_-0.2 x 10^7 M_sun within ~42.4 pc (2"). We also explore the presence of an intermediate mass black hole and show that models with a black hole as massive as M_bh = 5.0 x 10^5 M_sun are consistent with the available data. Regardless of whether a black hole is present or not, the nuclear cluster is vertically anisotropic (beta_z < 0), as was found with earlier two-integral models. We then use the models as initial conditions for N-body simulations. These simu...

  15. Network Coding in the Bidirectional Cross

    DEFF Research Database (Denmark)

    Ertli, Gergö; Paramanathan, Achuthan; Rein, Stephan Alexander;

    2013-01-01

    This paper presents a detailed performance evaluation of inter-session network coding in wireless meshed networks in terms of throughput and energy consumption. A full analytical model is given for three different communication approaches for the bidirectional cross topology using an IEEE 802.......11 medium access. One of the three approaches is pure relaying, while the other two approaches are using network coding with and without overhearing of other flows. The main outcome of the paper is that network coding without and with overhearing can increase the throughput by the factor of two and four......, respectively, for high load scenarios. Furthermore we show that the energy/bit ratio is decreased by the use of network coding approaches, underlining that the added complexity of network coding pays off when considering the overall system....

  16. Model for bidirectional movement of cytoplasmic dynein

    CERN Document Server

    Sumathy, S

    2014-01-01

    Cytoplasmic dynein exhibits a directional processive movement on microtubule filaments and is known to move in steps of varying length based on the number of ATP molecules bound to it and the load that it carries. It is experimentally observed that dynein takes occasional backward steps and the frequency of such backward steps increases as the load approaches the stall force. Using a stochastic process model, we investigate the bidirectional movement of single head of a dynein motor. The probability for backward step is implemented based on Crook's fluctuation theorem of non-equilibrium statistical mechanics. We find that the movement of dynein motor is characterized with negative velocity implying backward motion beyond stall force. We observe that the motor moves backward for super stall forces by hydrolyzing the ATP exactly the same way as it does while moving forward for sub stall forces.

  17. Dynamic assembly of brambleberry mediates nuclear envelope fusion during early development.

    Science.gov (United States)

    Abrams, Elliott W; Zhang, Hong; Marlow, Florence L; Kapp, Lee; Lu, Sumei; Mullins, Mary C

    2012-08-03

    To accommodate the large cells following zygote formation, early blastomeres employ modified cell divisions. Karyomeres are one such modification, mitotic intermediates wherein individual chromatin masses are surrounded by nuclear envelope; the karyomeres then fuse to form a single mononucleus. We identified brambleberry, a maternal-effect zebrafish mutant that disrupts karyomere fusion, resulting in formation of multiple micronuclei. As karyomeres form, Brambleberry protein localizes to the nuclear envelope, with prominent puncta evident near karyomere-karyomere interfaces corresponding to membrane fusion sites. brambleberry corresponds to an unannotated gene with similarity to Kar5p, a protein that participates in nuclear fusion in yeast. We also demonstrate that Brambleberry is required for pronuclear fusion following fertilization in zebrafish. Our studies provide insight into the machinery required for karyomere fusion and suggest that specialized proteins are necessary for proper nuclear division in large dividing blastomeres.

  18. Dynamic Assembly of Brambleberry Mediates Nuclear Envelope Fusion during Early Development

    Science.gov (United States)

    Abrams, Elliott W.; Zhang, Hong; Marlow, Florence L.; Kapp, Lee; Lu, Sumei; Mullins, Mary C.

    2012-01-01

    Summary To accommodate the large cells following zygote formation, early blastomeres employ modified cell divisions. Karyomeres are one such modification, a mitotic intermediate wherein individual chromatin masses are surrounded by nuclear envelope, which then fuse to form a single mononucleus. We identified brambleberry, a maternal-effect zebrafish mutant that disrupts karyomere fusion resulting in formation of multiple micronuclei. brambleberry is a previously unannotated gene homologous to Kar5p, which participates in nuclear fusion in yeast. We demonstrate that Brambleberry is required for pronuclear fusion following fertilization in zebrafish. As karyomeres form, Brambleberry localizes to the nuclear envelope with prominent puncta evident near karyomere-karyomere interfaces corresponding to membrane fusion sites. Our studies identify the first factor acting in karyomere fusion and suggest that specialized proteins are necessary for proper nuclear division in large dividing blastomeres. PMID:22863006

  19. Nuclear power plant status diagnostics using a neural network with dynamic node architecture

    Energy Technology Data Exchange (ETDEWEB)

    Basu, A.

    1992-12-31

    This thesis is part of an ongoing project at Iowa State University to develop ANN based fault diagnostic systems to detect and classify operational transients at nuclear power plants. The project envisages the deployment of such an advisor at Iowa Electric Light and Power Company`s Duane Arnold Energy Center nuclear power plant located at Palo, IA. This advisor is expected to make status diagnosis in real time, thus providing the operators with more time for corrective measures.

  20. Nuclear power plant status diagnostics using a neural network with dynamic node architecture

    Energy Technology Data Exchange (ETDEWEB)

    Basu, A.

    1992-01-01

    This thesis is part of an ongoing project at Iowa State University to develop ANN based fault diagnostic systems to detect and classify operational transients at nuclear power plants. The project envisages the deployment of such an advisor at Iowa Electric Light and Power Company's Duane Arnold Energy Center nuclear power plant located at Palo, IA. This advisor is expected to make status diagnosis in real time, thus providing the operators with more time for corrective measures.

  1. Molecular Dynamics Simulation of Lead Borate and Related Glasses in Multicomponent Systems for Low Melting Vitrification of Nuclear Wastes

    Science.gov (United States)

    Kato, S.; Sakida, S.; Benino, Y.; Nanba, T.

    2011-03-01

    Glasses based on lead oxide have excellent properties in general such as low melting point, high chemical durability and high stability of glassy form, which are suitable for the preservation of volatile nuclear wastes in a permanent vitrified form. In order to confirm the long-term performance of lead borate based glasses it is necessary to establish dissolution and diffusion processes based on a reliable model of the glass structure. In the present study molecular dynamics (MD) simulation of lead borate based glasses was carried out introducing a dummy negative point charge to reproduce asymmetric PbOn units. Parameters for the dummy charge were optimized based on the comparison between calculated radial distribution function and experimental one. Asymmetric coordination around Pb, for example trigonal bipyramid, was successfully reproduced in the MD simulated binary and ternary glass models. The simple model using the dummy charge was confirmed to be valid for further simulations of multicomponent glasses containing nuclear wastes and heavy elements.

  2. 2nd International Symposium "Atomic Cluster Collisions : Structure and Dynamics from the Nuclear to the Biological Scale"

    CERN Document Server

    Solov'yov, Andrey; ISACC 2007; Latest advances in atomic cluster collisions

    2008-01-01

    This book presents a 'snapshot' of the most recent and significant advances in the field of cluster physics. It is a comprehensive review based on contributions by the participants of the 2nd International Symposium on Atomic Cluster Collisions (ISACC 2007) held in July 19-23, 2007 at GSI, Darmstadt, Germany. The purpose of the Symposium is to promote the growth and exchange of scientific information on the structure and properties of nuclear, atomic, molecular, biological and complex cluster systems studied by means of photonic, electronic, heavy particle and atomic collisions. Particular attention is devoted to dynamic phenomena, many-body effects taking place in cluster systems of a different nature - these include problems of fusion and fission, fragmentation, collective electron excitations, phase transitions, etc.Both the experimental and theoretical aspects of cluster physics, uniquely placed between nuclear physics on the one hand and atomic, molecular and solid state physics on the other, are discuss...

  3. Arabidopsis chromatin-associated HMGA and HMGB use different nuclear targeting signals and display highly dynamic localization within the nucleus

    DEFF Research Database (Denmark)

    Launholt, Dorte; Merkle, Thomas; Houben, Andreas;

    2006-01-01

    HMGproteins appear to be involved in the regulation of transcription and other DNA-dependent processes. We have examined the subcellular localization of Arabidopsis thaliana HMGA, HMGB1, and HMGB5, revealing that they localize to the cell nucleus. They display a speckled distribution pattern throughout the chromatin...... of interphase nuclei, whereas none of the proteins associate with condensed mitotic chromosomes. HMGA is targeted to the nucleus by a monopartite nuclear localization signal, while efficient nuclear accumulation of HMGB1/5 requires large portions of the basic N-terminal part of the proteins. The acidic C......-terminal domain interferes with nucleolar targeting of HMGB1. Fluorescence recovery after photobleaching experiments revealed that HMGA and HMGB proteins are extremely dynamic in the nucleus, indicating that they bind chromatin only transiently before moving on to the next site, thereby continuously scanning...

  4. Using Nuclear Magnetic Resonance to Assess and Optimize the Precision of Methods for Controlling Quantum Dynamics

    Science.gov (United States)

    2005-07-31

    Kraus, Lindblad and matrix representations of quantum dynamical semigroups ,” J. Math. Phys. 44:534-57 (2003). N. Boulant, T. F. Havel, M. A. Pravia and...Education Research: Quantum Mechanics, Mt. Holyoke College, MA (June, `02). "Quantum dynamical semigroup tomography," talk presented at the AMS...dynamical semigroups ,” J. Math. Phys. 44:534-57 (2003). Abstract. Given a quantum dynamical semigroup expressed as an exponential superoperator acting on

  5. Nuclear quantum effect on hydrogen adsorption site of zeolite-templated carbon model using path integral molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Kimichi, E-mail: ki-suzuki@aist.go.jp [Research Institute for Nanosystem, National Institute of Advanced Industrial Science and Technology, Chuo-2, 1-1-1, Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Kayanuma, Megumi [Institut de Chimie, UMR 7177 CNRS/Universite de Strasbourg, 4 rue Blaise Pascal 67000, Strasbourg (France); Tachikawa, Masanori [Quantum Chemistry Division, Graduate School of Science, Yokohama-city University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027 (Japan); Ogawa, Hiroshi [Research Institute for Nanosystem, National Institute of Advanced Industrial Science and Technology, Chuo-2, 1-1-1, Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Nishihara, Hirotomo; Kyotani, Takashi [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Nagashima, Umpei [Research Institute for Nanosystem, National Institute of Advanced Industrial Science and Technology, Chuo-2, 1-1-1, Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

    2011-09-15

    Research highlights: > The stable hydrogen adsorption sites on C{sub 36}H{sub 12} were evaluated at 300 K using path integral molecular dynamics. > In the static MO calculation and conventional MD simulation, five stable adsorption sites of hydrogen atom were found. > In path integral simulation, only four stable adsorption sites were obtained. > The thermal and nuclear quantum effects are key role to settle the hydrogen adsorption sites on carbon materials. - Abstract: To settle the hydrogen adsorption sites on buckybowl C{sub 36}H{sub 12}, which is picked up from zeolite-templated carbon (ZTC), we have performed path integral molecular dynamics (PIMD) simulation including thermal and nuclear quantum fluctuations under semi-empirical PM3 method. In the static PM3 calculation and classical simulation the five stable adsorption sites of hydrogen atom are optimized inside a buckybowl C{sub 36}H{sub 12}, which are labeled as {alpha}-, {beta}{sub 1}-, {beta}{sub 2}-, {gamma}-, and {delta}-carbons from edge to innermost carbon. In PIMD simulation, meanwhile, stable adsorption site is not appeared on {delta}-carbon, but on only {alpha}-, {beta}{sub 1}-, {beta}{sub 2}-, and {gamma}-carbons. This result is due to the fact that the adsorbed hydrogen atom can easily go over the barrier for hydrogen transferring from {delta}- to {beta}{sub 1}-carbons by thermal and nuclear quantum fluctuations. The thermal and nuclear quantum effects are key role to settle the hydrogen adsorption sites on carbon materials.

  6. Bidirectional LSTM-CRF Models for Sequence Tagging

    OpenAIRE

    Huang, Zhiheng; Xu, Wei; Yu, Kai

    2015-01-01

    In this paper, we propose a variety of Long Short-Term Memory (LSTM) based models for sequence tagging. These models include LSTM networks, bidirectional LSTM (BI-LSTM) networks, LSTM with a Conditional Random Field (CRF) layer (LSTM-CRF) and bidirectional LSTM with a CRF layer (BI-LSTM-CRF). Our work is the first to apply a bidirectional LSTM CRF (denoted as BI-LSTM-CRF) model to NLP benchmark sequence tagging data sets. We show that the BI-LSTM-CRF model can efficiently use both past and fu...

  7. Activities report in nuclear physics

    NARCIS (Netherlands)

    Jansen, J. F. W.; Scholten, O.

    1987-01-01

    Experimental studies of giant resonances, nuclear structure, light mass systems, and heavy mass systems are summarized. Theoretical studies of nuclear structure, and dynamics are described. Electroweak interactions; atomic and surface physics; applied nuclear physics; and nuclear medicine are discus

  8. Evaluation of a regional air-quality model with bi-directional NH3 exchange coupled to an agro-ecosystem model

    Directory of Open Access Journals (Sweden)

    J. E. Pleim

    2012-08-01

    Full Text Available Atmospheric ammonia (NH3 is the primary atmospheric base and an important precursor for inorganic particulate matter and when deposited NH3 contributes to surface water eutrophication, soil acidification and decline in species biodiversity. Flux measurements indicate that the air-surface exchange of NH3 is bi-directional. However, the effects of bi-directional exchange, soil biogeochemistry and human activity are not parameterized in air quality models. The US Environmental Protection Agency (EPA's Community Multiscale Air-Quality (CMAQ model with bi-directional NH3 exchange has been coupled with the United States Department of Agriculture (USDA's Environmental Policy Integrated Climate (EPIC agro-ecosystem model's nitrogen geochemistry algorithms. CMAQ with bi-directional NH3 exchange coupled to EPIC connects agricultural cropping management practices to emissions and atmospheric concentrations of reduced nitrogen and models the biogeochemical feedback on NH3 air-surface exchange. This coupled modeling system reduced the biases and error in NHx (NH3 + NH4+ wet deposition and in ambient aerosol concentrations in an annual 2002 Continental US (CONUS domain simulation when compared to a 2002 annual simulation of CMAQ without bi-directional exchange. Fertilizer emissions estimated in CMAQ 5.0 with bi-directional exchange exhibits markedly different seasonal dynamics than the US EPA's National Emissions Inventory (NEI, with lower emissions in the spring and fall and higher emissions in July.

  9. Dynamic SPR monitoring of yeast nuclear protein binding to a cis-regulatory element.

    Science.gov (United States)

    Mao, Grace; Brody, James P

    2007-11-09

    Gene expression is controlled by protein complexes binding to short specific sequences of DNA, called cis-regulatory elements. Expression of most eukaryotic genes is controlled by dozens of these elements. Comprehensive identification and monitoring of these elements is a major goal of genomics. In pursuit of this goal, we are developing a surface plasmon resonance (SPR) based assay to identify and monitor cis-regulatory elements. To test whether we could reliably monitor protein binding to a regulatory element, we immobilized a 16bp region of Saccharomyces cerevisiae chromosome 5 onto a gold surface. This 16bp region of DNA is known to bind several proteins and thought to control expression of the gene RNR1, which varies through the cell cycle. We synchronized yeast cell cultures, and then sampled these cultures at a regular interval. These samples were processed to purify nuclear lysate, which was then exposed to the sensor. We found that nuclear protein binds this particular element of DNA at a significantly higher rate (as compared to unsynchronized cells) during G1 phase. Other time points show levels of DNA-nuclear protein binding similar to the unsynchronized control. We also measured the apparent association complex of the binding to be 0.014s(-1). We conclude that (1) SPR-based assays can monitor DNA-nuclear protein binding and that (2) for this particular cis-regulatory element, maximum DNA-nuclear protein binding occurs during G1 phase.

  10. The Bi-directional Moving Structures in a Coronal Bright Point

    CERN Document Server

    Li, Dong; Su, Yingna

    2016-01-01

    We report the bi-directional moving structures in a coronal bright point (CBP) on 2015 July 14. It is observed by the Atmospheric Imaging Assembly (AIA) onboard Solar Dynamics Observatory (SDO). This CBP has a lifetime of about 10 minutes, and a curved shape. The observations show that many bright structures are moving intermittently outward from the CBP brightness core. Such moving structures are clearly seen at AIA 171, 193, 211, 131, 94, 335 and 304 A, slit-jaw (SJI) 1330 and 1400 A. In order to analyze these moving structures, the CBP is cut along the moving direction with a curved slit from the AIA and SJI images. Then we can obtain the time-distance slices, including the intensity and intensity-derivative diagrams, from which, the moving structures are recognized as the oblique streaks, and they are characterized by the bi-direction, simultaneity, symmetry, and periodicity. The average speed is around 300 km/s, while the typically period is about 90 s. All these features (including the bi-directional fl...

  11. Bidirectional transport by molecular motors: enhanced processivity and response to external forces.

    Science.gov (United States)

    Müller, Melanie J I; Klumpp, Stefan; Lipowsky, Reinhard

    2010-06-02

    Intracellular transport along cytoskeletal filaments is often mediated by two teams of molecular motors that pull on the same cargo and move in opposite directions along the filaments. We have recently shown theoretically that this bidirectional transport can be understood as a stochastic tug-of-war between the two motor teams. Here, we further develop our theory to investigate the experimentally accessible dynamic behavior of cargos transported by strong motors such as kinesin-1 or cytoplasmic dynein. By studying the run and binding times of such a cargo, we show that the properties of biological motors, such as the large ratio of stall/detachment force and the small ratio of superstall backward/forward velocity, are favorable for bidirectional cargo transport, leading to fast motion and enhanced diffusion. In addition, cargo processivity is shown to be strongly enhanced by transport via several molecular motors even if these motors are engaged in a tug-of-war. Finally, we study the motility of a bidirectional cargo under force. Frictional forces arising, e.g., from the viscous cytoplasm, lead to peaks in the velocity distribution, while external forces as exerted, e.g., by an optical trap, lead to hysteresis effects. Our results, in particular our explicit expressions for the cargo binding time and the distance of the peaks in the velocity relation under friction, are directly accessible to in vitro as well as in vivo experiments.

  12. Continuous measurements of real-life bidirectional pedestrian flows on a wide walkway

    CERN Document Server

    Corbetta, Alessandro; Lee, Chung-min; Toschi, Federico

    2016-01-01

    Employing partially overlapping overhead \\kinectTMS sensors and automatic pedestrian tracking algorithms we recorded the crowd traffic in a rectilinear section of the main walkway of Eindhoven train station on a 24/7 basis. Beside giving access to the train platforms (it passes underneath the railways), the walkway plays an important connection role in the city. Several crowding scenarios occur during the day, including high- and low-density dynamics in uni- and bi-directional regimes. In this paper we discuss our recording technique and we illustrate preliminary data analyses. Via fundamental diagrams-like representations we report pedestrian velocities and fluxes vs. pedestrian density. Considering the density range $0$ - $1.1\\,$ped/m$^2$, we find that at densities lower than $0.8\\,$ped/m$^2$ pedestrians in unidirectional flows walk faster than in bidirectional regimes. On the opposite, velocities and fluxes for even bidirectional flows are higher above $0.8\\,$ped/m$^2$.

  13. Bi-directional electrons in the near-Earth plasma sheet

    Directory of Open Access Journals (Sweden)

    K. Shiokawa

    Full Text Available We have studied the occurrence characteristics of bi-directional electron pitch angle anisotropy (enhanced flux in field-aligned directions, F^ /F|| > 1.5 at energies of 0.1–30 keV using plasma and magnetic field data from the AMPTE/IRM satellite in the near-Earth plasma sheet. The occurrence rate increases in the tailward direction from XGSM = - 9 RE to - 19 RE . The occurrence rate is also enhanced in the midnight sector, and furthermore, whenever the elevation angle of the magnetic field is large while the magnetic field intensity is small, B ~ 15 nT. From these facts, we conclude that the bi-directional electrons in the central plasma sheet are produced mainly in the vicinity of the neutral sheet and that the contribution from ionospheric electrons is minor. A high occurrence is also found after earthward high-speed ion flows, suggesting Fermi-type field-aligned electron acceleration in the neutral sheet. Occurrence characteristics of bi-directional electrons in the plasma sheet boundary layer are also discussed.

    Key words. Magnetospheric physics (magnetospheric configuration and dynamics; magnetotail; plasma sheet

  14. Influence of nuclear dissipation on fission dynamics of the excited nucleus $^{248}$Cf within a stochastic approach

    Indian Academy of Sciences (India)

    ESLAMIZADEH HADI

    2016-07-01

    A stochastic approach to fission dynamics based on two-dimensional Langevin equations was applied to calculate the anisotropy of the fission fragments angular distribution and average pre-scission neutron multiplicities for the compound nucleus 248Cf formed in the $${16}$O+$^{232}$Th reactions. Postsaddle nuclear dissipation strength of $(12–14) \\times 10^{21} s^{−1}$ was extracted for Cf nucleus by fitting the results of calculations with the experimentaldata. Furthermore, it was found that the results of calculations for the anisotropy of the fission fragments angular distribution and pre-scission neutron multiplicities are very sensitive to the magnitude of post-saddle nucleardissipation.

  15. On the causal dynamics between emissions, nuclear energy, renewable energy, and economic growth

    Energy Technology Data Exchange (ETDEWEB)

    Apergis, Nicholas [Department of Banking and Financial Management, University of Piraeus, Karaoli and Dimitriou 80, Piraeus, ATTIKI 18534 (Greece); Payne, James E. [Department of Economics, Illinois State University, Normal, IL 61790-4200 (United States); Menyah, Kojo [London Metropolitan Business School, London Metropolitan University, 84 Moorgate, London, EC2M 6SQ (United Kingdom); Wolde-Rufael, Yemane

    2010-09-15

    This paper examines the causal relationship between CO{sub 2} emissions, nuclear energy consumption, renewable energy consumption, and economic growth for a group of 19 developed and developing countries for the period 1984-2007 using a panel error correction model. The long-run estimates indicate that there is a statistically significant negative association between nuclear energy consumption and emissions, but a statistically significant positive relationship between emissions and renewable energy consumption. The results from the panel Granger causality tests suggest that in the short-run nuclear energy consumption plays an important role in reducing CO{sub 2} emissions whereas renewable energy consumption does not contribute to reductions in emissions. This may be due to the lack of adequate storage technology to overcome intermittent supply problems as a result electricity producers have to rely on emission generating energy sources to meet peak load demand. (author)

  16. Dynamic Isovector Reorientation of Deuteron as a Probe to Nuclear Symmetry Energy.

    Science.gov (United States)

    Ou, Li; Xiao, Zhigang; Yi, Han; Wang, Ning; Liu, Min; Tian, Junlong

    2015-11-20

    We present the calculations on a novel reorientation effect of deuteron attributed to isovector interaction in the nuclear field of heavy target nuclei. The correlation angle determined by the relative momentum vector of the proton and the neutron originating from the breakup deuteron, which is experimentally detectable, exhibits significant dependence on the isovector nuclear potential but is robust against the variation of the isoscaler sector. In terms of sensitivity and cleanness, the breakup reactions induced by the polarized deuteron beam at about 100 MeV/u provide a more stringent constraint to the symmetry energy at subsaturation densities.

  17. Dynamic Imaging of Fluid Flow in Sandstones by Nuclear Emission Tomography

    Science.gov (United States)

    Pini, Ronny; Benson, Sally; Druhan, Jenny; Hingerl, Ferdinand; O'Neil, James P.; Vandehey, Nicholas T.

    2014-05-01

    The heterogeneity of geological formations varies over a wide range of length-scales and represents a major challenge for predicting the movement of fluids in the subsurface. Millimeters to cm-scale features that are commonly observed in sedimentary rocks have been shown to greatly influence fluid transport over much larger observational scales. From a practical perspective, these features give rise to capillary phenomena that affect process-relevant parameters, such as sweep or trapping efficiencies. Measurements on core samples represent a major input for field-scale flow models and the latter adopt multistage up-scaling approaches to link the core-scale to the size of a grid-block. The lack of access to information about rock property heterogeneity at the sub-core scale has restricted the ability to fully take advantage of these methods; in fact, properties derived from the latter are inherently "effective", their spatial resolution being limited to a minimum of several centimeters by the measurement or sampling technique. However, making accurate predictions of multiphase flows and dispersion coefficients for single phase flow requires making measurements at the full range of relevant spatial scales, thus referring to the internal structure of the sample and the small-scale features described above. Essential components in this description include continuum properties that are related to the rock (porosity and permeability), to the fluids (saturation) and to both of them (capillary pressure-saturation relationship); the ability to create a link among all these properties is key to a physically-sound description of these naturally complex systems. One way to accomplish this is by adopting an integrated approach that combines displacement experiments in naturally heterogeneous core-samples with the simultaneous imaging of flow as well as with the support of detailed numerical simulations. In this paper, nuclear emission tomography is applied to visualize fluid

  18. Quantum Dynamics and Spectroscopy of Ab Initio Liquid Water: The Interplay of Nuclear and Electronic Quantum Effects.

    Science.gov (United States)

    Marsalek, Ondrej; Markland, Thomas E

    2017-03-22

    Understanding the reactivity and spectroscopy of aqueous solutions at the atomistic level is crucial for the elucidation and design of chemical processes. However, the simulation of these systems requires addressing the formidable challenges of treating the quantum nature of both the electrons and nuclei. Exploiting our recently developed methods that provide acceleration by up to 2 orders of magnitude, we combine path integral simulations with on-the-fly evaluation of the electronic structure at the hybrid density functional theory level to capture the interplay between nuclear quantum effects and the electronic surface. Here we show that this combination provides accurate structure and dynamics, including the full infrared and Raman spectra of liquid water. This allows us to demonstrate and explain the failings of lower-level density functionals for dynamics and vibrational spectroscopy when the nuclei are treated quantum mechanically. These insights thus provide a foundation for the reliable investigation of spectroscopy and reactivity in aqueous environments.

  19. Safety assessment for electricity generation failure accident of gas cooled nuclear power plant using system dynamics (SD) method

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Tae Ho [Seoul National Univ. (Korea, Republic of). Dept. of Nuclear Engineering

    2013-04-15

    The power production failure happens in the loss of coolant of the nuclear power plants (NPPs). The air ingress is a serious accident in gas cooled NPPs. The quantification of the study performed by the system dynamics (SD) method which is processed by the feedback algorithms. The Vensim software package is used for the simulation, which is performed by the Monte-Carlo method. Two kinds of considerations as the economic and safety properties are important in NPPs. The result shows the stability of the operation when the power can be decided. The maximum value of risk is the 11.77 in 43rd and the minimum value is 0.0 in several years. So, the success of the circulation of coolant is simulated by the dynamical values. (orig.)

  20. Learning, innovation and communication: evolving dynamics of a nuclear emergency plan; Aprendizagem, inovacao e comunicacao: a dinamica evolutica de um plano de emergencia nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Quadros, Andre Luiz Lopes

    2014-07-01

    The technological development inherent to modern societies has placed human beings in situations of choice from a wide variety of possible risks. As a way to protect people and the environment, actions need to be developed in order to reduce possible consequences of the materialisation of these risks. The thermonuclear power generation demand planning in order to prepare answers to possible emergency situations, as even being considered of low probability of occurrence, when they happen have a significant impact on populations and regions of its surroundings. Considering the relevance of this issue, this thesis aimed to identify and analyze the dynamics of preparedness and response to emergency situations in a Nuclear Power Plant, trying to understand its evolution over the time and systematizing it, considering the actors involved, processes of organizational learning, innovation and risk communication, considered as crucial for the development and improvement of emergency plans. Concerning preparedness and response to possible emergency situations in this nuclear plant, it was possible not only to confirm the importance of the three processes studied, but also observe that they can be treated and evaluated in an integrated and systematic way. So, it was presented a model that aims to facilitate the understanding of this perspective and enhance the importance of participation and cooperation between all stakeholders (organizations and the local population) within a socio-participatory perspective. To this end, this exploratory research sought for evidences in documents, participation in planning meetings, direct observation of the general exercises of the CNAAA External Emergency Plan of 2013, interviews with some of the actors involved and through the application of a questionnaire among the population of the Praia Vermelha, in Angra dos Reis, Rio de Janeiro. (author)

  1. Electronic bidirectional valve circuit prevents crossover distortion and threshold effect

    Science.gov (United States)

    Kernick, A.

    1966-01-01

    Four-terminal network forms a bidirectional valve which will switch or alternate an ac signal without crossover distortion or threshold effect. In this network, an isolated control signal is sufficient for circuit turn-on.

  2. Silent and Efficient Supersonic Bi-Directional Flying Wing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a Phase I study for a novel concept of a supersonic bi-directional (SBiDir) flying wing (FW) that has the potential to revolutionize supersonic flight...

  3. Effect of particle nonsphericity on bidirectional reflectance of cirrus clouds

    Energy Technology Data Exchange (ETDEWEB)

    Mishchenko, M.I.; Rossow, W.B.; Macke, A.; Lacis, A.A. [Goddard Institute for Space Studies, New York, NY (United States)

    1996-04-01

    This paper describes the use of the fractal ice particle method to study the differences in bidirectional reflectance caused by the differences in the single scattering phase functions of spherical water droplets and nonspherical ice crystals.

  4. Ab initio molecular dynamics with nuclear quantum effects at classical cost: Ring polymer contraction for density functional theory.

    Science.gov (United States)

    Marsalek, Ondrej; Markland, Thomas E

    2016-02-07

    Path integral molecular dynamics simulations, combined with an ab initio evaluation of interactions using electronic structure theory, incorporate the quantum mechanical nature of both the electrons and nuclei, which are essential to accurately describe systems containing light nuclei. However, path integral simulations have traditionally required a computational cost around two orders of magnitude greater than treating the nuclei classically, making them prohibitively costly for most applications. Here we show that the cost of path integral simulations can be dramatically reduced by extending our ring polymer contraction approach to ab initio molecular dynamics simulations. By using density functional tight binding as a reference system, we show that our ring polymer contraction scheme gives rapid and systematic convergence to the full path integral density functional theory result. We demonstrate the efficiency of this approach in ab initio simulations of liquid water and the reactive protonated and deprotonated water dimer systems. We find that the vast majority of the nuclear quantum effects are accurately captured using contraction to just the ring polymer centroid, which requires the same number of density functional theory calculations as a classical simulation. Combined with a multiple time step scheme using the same reference system, which allows the time step to be increased, this approach is as fast as a typical classical ab initio molecular dynamics simulation and 35× faster than a full path integral calculation, while still exactly including the quantum sampling of nuclei. This development thus offers a route to routinely include nuclear quantum effects in ab initio molecular dynamics simulations at negligible computational cost.

  5. The impact of monochloramine on the diversity and dynamics of Legionella pneumophila subpopulations in a nuclear power plant cooling circuit.

    Science.gov (United States)

    Jakubek, Delphine; Le Brun, Matthieu; Leblon, Gerard; DuBow, Michael; Binet, Marie

    2013-08-01

    Members of the pathogenic Legionella genus encounter suitable growth conditions in nuclear power plant cooling circuits. To limit its proliferation and ensure that levels remain below regulatory thresholds, chemical treatment with monochloramine can be used in continuous or sequential conditions. The aim of this study was to determine the impact of monochloramine on L. pneumophila subpopulations in the cooling circuits of a nuclear power plant. The chosen procedure involved monitoring the diversity and dynamics of L. pneumophila subpopulations every month over the course of a year in a nuclear power plant cooling circuit, which was treated for 2 months during the period under study. This study confirmed the effectiveness of monochloramine to limit L. pneumophila concentrations in cooling circuits. The culturable L. pneumophila community was strongly affected by the injection of monochloramine. Several subpopulations persisted during treatment at low concentrations (below the detection limit of standard methods), suggesting that the susceptibility of L. pneumophila is strain dependent. Although the composition of the subpopulations was not similar, the resilience of the community structure was observed. Indeed, the community eventually returned to its initial structure and presented a similar pattern of richness, diversity and uniformity to that seen before treatment.

  6. Applications of dynamic nuclear polarization to the study of reactions and reagents in organic and biomolecular chemistry.

    Science.gov (United States)

    Hilty, Christian; Bowen, Sean

    2010-08-07

    Nuclear Magnetic Resonance (NMR) is an important spectroscopic tool for the identification and structural characterization of molecules in chemistry and biochemistry. The most significant limitation of NMR compared to other spectroscopies is its relatively low sensitivity, which thus often requires long measurement times or large amounts of sample. A way of increasing sensitivity of single scan NMR spectra by several orders of magnitude is through hyperpolarization of nuclear spins. Dynamic nuclear polarization allows hyperpolarization of most spins in small molecules encountered in chemistry and biochemistry. NMR spectra of small amounts of samples from natural source, or from chemical synthesis can readily be acquired. Perhaps more interestingly, the availability of the entire hyperpolarized NMR signal in one single scan allows the measurement of transient processes in real time, if applied together with a stopped-flow technique. Through observation of chemical shift, different reactant and product species can be distinguished, and kinetics and mechanisms, for example in enzyme catalyzed reactions, can be elucidated. Real-time hyperpolarization-enhanced NMR is uniquely amenable to correlating atomic positions not only through space, but also over time between reactant and product species. Such correlations carry mechanistic information about a reaction, and can prove reaction pathways. Applications of this technique are emerging in different areas of chemistry concerned with rapid reactions, including not only enzymatic processes, but also chemical catalysis and protein folding.

  7. Structure, dynamics, evolution, and function of a major scaffold component in the nuclear pore complex.

    Science.gov (United States)

    Sampathkumar, Parthasarathy; Kim, Seung Joong; Upla, Paula; Rice, William J; Phillips, Jeremy; Timney, Benjamin L; Pieper, Ursula; Bonanno, Jeffrey B; Fernandez-Martinez, Javier; Hakhverdyan, Zhanna; Ketaren, Natalia E; Matsui, Tsutomu; Weiss, Thomas M; Stokes, David L; Sauder, J Michael; Burley, Stephen K; Sali, Andrej; Rout, Michael P; Almo, Steven C

    2013-04-02

    The nuclear pore complex, composed of proteins termed nucleoporins (Nups), is responsible for nucleocytoplasmic transport in eukaryotes. Nuclear pore complexes (NPCs) form an annular structure composed of the nuclear ring, cytoplasmic ring, a membrane ring, and two inner rings. Nup192 is a major component of the NPC's inner ring. We report the crystal structure of Saccharomyces cerevisiae Nup192 residues 2-960 [ScNup192(2-960)], which adopts an α-helical fold with three domains (i.e., D1, D2, and D3). Small angle X-ray scattering and electron microscopy (EM) studies reveal that ScNup192(2-960) could undergo long-range transition between "open" and "closed" conformations. We obtained a structural model of full-length ScNup192 based on EM, the structure of ScNup192(2-960), and homology modeling. Evolutionary analyses using the ScNup192(2-960) structure suggest that NPCs and vesicle-coating complexes are descended from a common membrane-coating ancestral complex. We show that suppression of Nup192 expression leads to compromised nuclear transport and hypothesize a role for Nup192 in modulating the permeability of the NPC central channel.

  8. Bidirectional uncompressed HD video distribution over fiber employing VCSELs

    DEFF Research Database (Denmark)

    Estaran Tolosa, Jose Manuel; Vegas Olmos, Juan José; Rodes, G. A.;

    2012-01-01

    We report on a bidirectional system in which VCSELs are simultaneously modulated with two uncompressed HD video signals. The results show a large power budget and a negligible penalty over 10 km long transmission links.......We report on a bidirectional system in which VCSELs are simultaneously modulated with two uncompressed HD video signals. The results show a large power budget and a negligible penalty over 10 km long transmission links....

  9. Projective synchronization of chaotic systems with bidirectional nonlinear coupling

    Indian Academy of Sciences (India)

    Mohammada Ali Khan; Swarup Poria

    2013-09-01

    This paper presents a new scheme for constructing bidirectional nonlinear coupled chaotic systems which synchronize projectively. Conditions necessary for projective synchronization (PS) of two bidirectionally coupled chaotic systems are derived using Lyapunov stability theory. The proposed PS scheme is discussed by taking as examples the so-called unified chaotic model, the Lorenz–Stenflo system and the nonautonomous chaotic Van der Pol oscillator. Numerical simulation results are presented to show the efficiency of the proposed synchronization scheme.

  10. Global evaluation of ammonia bi-directional exchange

    OpenAIRE

    Zhu, L; D. Henze; J. Bash; G.-R. Jeong; Cady-Pereira, K.; Shephard, M; Luo, M; F. Paulot; Capps, S.

    2015-01-01

    Bi-directional air–surface exchange of ammonia (NH3) has been neglected in many air quality models. In this study, we implement the bi-directional exchange of NH3 in the GEOS-Chem global chemical transport model. We also introduce an updated diurnal variability scheme for NH3 livestock emissions and evaluate the recently developed MASAGE_NH3 bottom up inventory. While updated diurnal variability improves comparison of modeled-to-hourly in situ measurements i...

  11. Direct assessment of quantum nuclear effects on hydrogen bond strength by constrained-centroid ab initio path integral molecular dynamics

    Science.gov (United States)

    Walker, Brent; Michaelides, Angelos

    2010-11-01

    The impact of quantum nuclear effects on hydrogen (H-) bond strength has been inferred in earlier work from bond lengths obtained from path integral molecular dynamics (PIMD) simulations. To obtain a direct quantitative assessment of such effects, we use constrained-centroid PIMD simulations to calculate the free energy changes upon breaking the H-bonds in dimers of HF and water. Comparing ab initio simulations performed using PIMD and classical nucleus molecular dynamics (MD), we find smaller dissociation free energies with the PIMD method. Specifically, at 50 K, the H-bond in (HF)2 is about 30% weaker when quantum nuclear effects are included, while that in (H2O)2 is about 15% weaker. In a complementary set of simulations, we compare unconstrained PIMD and classical nucleus MD simulations to assess the influence of quantum nuclei on the structures of these systems. We find increased heavy atom distances, indicating weakening of the H-bond consistent with that observed by direct calculation of the free energies of dissociation.

  12. Interfacial Ca2+ environments in nanocrystalline apatites revealed by dynamic nuclear polarization enhanced 43Ca NMR spectroscopy

    Science.gov (United States)

    Lee, Daniel; Leroy, César; Crevant, Charlène; Bonhomme-Coury, Laure; Babonneau, Florence; Laurencin, Danielle; Bonhomme, Christian; De Paëpe, Gaël

    2017-01-01

    The interfaces within bones, teeth and other hybrid biomaterials are of paramount importance but remain particularly difficult to characterize at the molecular level because both sensitive and selective techniques are mandatory. Here, it is demonstrated that unprecedented insights into calcium environments, for example the differentiation of surface and core species of hydroxyapatite nanoparticles, can be obtained using solid-state NMR, when combined with dynamic nuclear polarization. Although calcium represents an ideal NMR target here (and de facto for a large variety of calcium-derived materials), its stable NMR-active isotope, calcium-43, is a highly unreceptive probe. Using the sensitivity gains from dynamic nuclear polarization, not only could calcium-43 NMR spectra be obtained easily, but natural isotopic abundance 2D correlation experiments could be recorded for calcium-43 in short experimental time. This opens perspectives for the detailed study of interfaces in nanostructured materials of the highest biological interest as well as calcium-based nanosystems in general. PMID:28128197

  13. A Study on the Dynamic Analysis of the Nuclear Fuel Test Rig Using 1-Way Fluid-Structure Coupled Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Tae-Ho; Hong, Jin-Tae; Ahn, Sung-Ho; Joung, Chang-Young; Heo, Sung-Ho; Jang, Seo-Yun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    1-way fluid-structure coupled analysis is used to estimate the dynamic characteristic of the fuel test rig. the motion at the bottom of the test rig is confirmed. The maximum deformation of the test rig is 0.11 mm. The structural integrity of the test rig is performed by using the comparison with the Von-mises stress of the analysis and yield stress of the material. It is evaluated that the motion at the bottom of the test rig is able to cause other structural problem. Using the 2-way fluid-structural coupled analysis, the structural integrity of the test rig will be performed in further paper. The cooling water with specific flow rate was flowed in the nuclear fuel test rig. The structural integrity of the test rig was affected by the vibration. The fluid-induced vibration test had to be performed to obtain the amplitude of the vibration on the structure. Various test systems was developed. Flow-induced vibration and pressure drop experimental tester was developed in Korea Atomic Energy Research Institute. The vibration test with high fluid flow rate was difficult by the tester. To generate the nuclear fuel test environment, coolant flow simulation system was developed. The scaled nuclear fuel test was able to be performed by the simulation system. The mock-up model of the test rig was used in the simulation system. The mock-up model in the simulation system was manufactured with scaled down full model. In this paper, the fluid induced vibration characteristic of the full model in the nuclear fuel test is studied. The hydraulic pressure on the velocity of the fluid was calculated. The static structure analysis was performed by using the pressure. The structural integrity was assessed using the results of the analysis.

  14. Study conformational dynamics of intrinsically disordered protein by PET-FCS (Conference Presentation)

    Science.gov (United States)

    Enderlein, Joerg; Zhou, Man; Van, Qui; Gregor, Ingo

    2016-02-01

    Intrinsically disordered proteins (IDP) form a large and functionally important class of proteins that lack an ordered three-dimensional structure. IDPs play an important role in cell signaling, transcription, or chromatin remodeling. The discovery of IDPs has challenged the traditional paradigm of protein structure which states that protein function depends on a well-defined three-dimensional structure. Due to their high conformational flexibility and the lack of ordered secondary structure, it is challenging to study the flexible structure, dynamics and energetics of these proteins with conventional methods. In our work, we employ photoinduced electron transfer (PET) combined with fluorescence correlation spectroscopy (FCS) for studying the conformational dynamics of one specific class of IDPs: phenylalanine-glycine rich protein domains (FG repeats) which are dominant building blocks within the pore of nuclear pore complexes. Nuclear pore complexes are large protein assemblies that cross the nuclear envelope and form selective barrier, which regulate bidirectional exchange between nucleus and cytoplasm.

  15. MECHANICAL AND THERMO–MECHANICAL PROPERTIES OF BI-DIRECTIONAL AND SHORT CARBON FIBER REINFORCED EPOXY COMPOSITES

    Directory of Open Access Journals (Sweden)

    G. AGARWAL

    2014-10-01

    Full Text Available This paper based on bidirectional and short carbon fiber reinforced epoxy composites reports the effect of fiber loading on physical, mechanical and thermo-mechanical properties respectively. The five different fiber loading, i.e., 10wt. %, 20wt. %, 30wt. %, 40wt. % and 50wt. % were taken for evaluating the above said properties. The physical and mechanical properties, i.e., hardness, tensile strength, flexural strength, inter-laminar shear strength and impact strength are determined to represent the behaviour of composite structures with that of fiber loading. Thermo-mechanical properties of the material are measured with the help of Dynamic Mechanical Analyser to measure the damping capacity of the material that is used to reduce the vibrations. The effect of storage modulus, loss modulus and tan delta with temperature are determined. Finally, Cole–Cole analysis is performed on both bidirectional and short carbon fiber reinforced epoxy composites to distinguish the material properties of either homogeneous or heterogeneous materials. The results show that with the increase in fiber loading the mechanical properties of bidirectional carbon fiber reinforced epoxy composites increases as compared to short carbon fiber reinforced epoxy composites except in case of hardness, short carbon fiber reinforced composites shows better results. Similarly, as far as Loss modulus, storage modulus is concerned bidirectional carbon fiber shows better damping behaviour than short carbon fiber reinforced composites.

  16. SEMICONDUCTOR INTEGRATED CIRCUITS: A self-adaptive full asynchronous bi-directional transmission channel for network-on-chips

    Science.gov (United States)

    Xuguang, Guan; Yintang, Yang; Zhangming, Zhu; Duan, Zhou

    2010-08-01

    To improve two shortcomings of conventional network-on-chips, i.e. low utilization rate in channels between routers and excessive interconnection lines, this paper proposes a full asynchronous self-adaptive bi-directional transmission channel. It can utilize interconnection lines and register resources with high efficiency, and dynamically detect the data transmission state between routers through a direction regulator, which controls the sequencer to automatically adjust the transmission direction of the bi-directional channel, so as to provide a flexible data transmission environment. Null convention logic units are used to make the circuit quasi-delay insensitive and highly robust. The proposed bi-directional transmission channel is implemented based on SMIC 0.18 μm standard CMOS technology. Post-layout simulation results demonstrate that this self-adaptive bi-directional channel has better performance on throughput, transmission flexibility and channel bandwidth utilization compared to a conventional single direction channel. Moreover, the proposed channel can save interconnection lines up to 30% and can provide twice the bandwidth resources of a single direction transmission channel. The proposed channel can apply to an on-chip network which has limited resources of registers and interconnection lines.

  17. Nuclear science research with dynamic high energy density plasmas at NIF

    Science.gov (United States)

    Shaughnessy, D. A.; Gharibyan, N.; Moody, K. J.; Despotopulos, J. D.; Grant, P. M.; Yeamans, C. B.; Berzak Hopkins, L.; Cerjan, C. J.; Schneider, D. H. G.; Faye, S.

    2016-05-01

    Nuclear reaction measurements are performed at the National Ignition Facility in a high energy density plasma environment by adding target materials to the outside of the hohlraum thermo-mechanical package on an indirect-drive exploding pusher shot. Materials are activated with 14.1-MeV neutrons and the post-shot debris is collected via the Solid Radiochemistry diagnostic, which consists of metal discs fielded 50 cm from target chamber center. The discs are removed post-shot and analyzed via radiation counting and mass spectrometry. Results from a shot using Nd and Tm foils as targets are presented, which indicate enhanced collection of the debris in the line of sight of a given collector. The capsule performance was not diminished due to the extra material. This provides a platform for future measurements of nuclear reaction data through the use of experimental packages mounted external to the hohlraum.

  18. Nuclear single-particle states: dynamical shell model and energy density functional methods

    CERN Document Server

    Bortignon, P F; Sagawa, H

    2010-01-01

    We discuss different approaches to the problem of reproducing the observed features of nuclear single-particle (s.p.) spectra. In particular, we analyze the dominant energy peaks, and the single-particle strength fragmentation, using the example of neutron states in 208Pb. Our main emphasis is the interpretation of that fragmentation as due to particle-vibration coupling (PVC). We compare with recent Energy Density Functional (EDF) approaches, and try to present a critical perspective.

  19. Soliton solutions of two bidirectional sixth-order partial differential equations belonging to the KP hierarchy

    Energy Technology Data Exchange (ETDEWEB)

    Verhoeven, C; Musette, M [Dienst Theoretische Natuurkunde, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels (Belgium)

    2003-02-28

    In this letter, we analyse two bidirectional sixth-order partial differential equations, which are reductions in (1 + 1) dimensions of equations belonging to the KP hierarchy. They have fourth-order and fifth-order Lax pairs, respectively. We derive their Baecklund transformations and, from the nonlinear superposition formula, we can build their soliton solutions like a Grammian. The interesting dynamics of these solitons is that they may describe not only the overtaking collision but also the head-on collision of solitary waves of different type and shape. (letter to the editor)

  20. A TTC upgrade proposal using bidirectional 10G-PON FTTH technology

    Science.gov (United States)

    Kolotouros, D. M.; Baron, S.; Soos, C.; Vasey, F.

    2015-04-01

    A new generation FPGA-based Timing-Trigger and Control (TTC) system based on emerging Passive Optical Network (PON) technology is being proposed to replace the existing off-detector TTC system used by the LHC experiments. High split ratio, dynamic software partitioning, low and deterministic latency, as well as low jitter are required. Exploiting the latest available technologies allows delivering higher capacity together with bidirectionality, a feature absent from the legacy TTC system. This article focuses on the features and capabilities of the latest TTC-PON prototype based on 10G-PON FTTH components along with some metrics characterizing its performance.

  1. Progress in spin dynamics solid-state nuclear magnetic resonance with the application of Floquet-Magnus expansion to chemical shift anisotropy.

    Science.gov (United States)

    Mananga, Eugene Stephane

    2013-01-01

    The purpose of this article is to present an historical overview of theoretical approaches used for describing spin dynamics under static or rotating experiments in solid state nuclear magnetic resonance. The article gives a brief historical overview for major theories in nuclear magnetic resonance and the promising theories. We present the first application of Floquet-Magnus expansion to chemical shift anisotropy when irradiated by BABA pulse sequence.

  2. Mengovirus-induced rearrangement of the nuclear pore complex: hijacking cellular phosphorylation machinery.

    NARCIS (Netherlands)

    Bardina, M.V.; Lidsky, P.V.; Sheval, E.V.; Fominykh, K.V.; Kuppeveld, F.J.M. van; Polyakov, V.Y.; Agol, V.I.

    2009-01-01

    Representatives of several picornavirus genera have been shown previously to significantly enhance non-controllable bidirectional exchange of proteins between nuclei and cytoplasm. In enteroviruses and rhinoviruses, enhanced permeabilization of the nuclear pores appears to be primarily due to proteo

  3. Coherent-states dynamics of the H{sup +} + HF reaction at E{sub Lab} = 30 eV: A complete electron nuclear dynamics investigation

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, Buddhadev [Department of Chemistry and Biochemistry, Texas Tech University, P.O. Box 41061, Lubbock, TX 79409-1061 (United States); Sadeghi, Raymond [Department of Chemistry, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249-0698 (United States); Austin, Anthony [Department of Chemistry and Biochemistry, Texas Tech University, P.O. Box 41061, Lubbock, TX 79409-1061 (United States); Morales, Jorge A. [Department of Chemistry and Biochemistry, Texas Tech University, P.O. Box 41061, Lubbock, TX 79409-1061 (United States)], E-mail: jorge.morales@ttu.edu

    2007-11-09

    Results of a complete investigation of the H{sup +} + HF reaction at E{sub Lab} = 30 eV with the electron nuclear dynamics (END) and the coherent-states dynamics (CSD) theories are herein presented. Current END-CSD methodology employs frozen Gaussian wave packet in the semiclassical limit of h {yields} 0 for the nuclei, and a single-determinantal Thouless coherent state (CS) for the electrons. The simulated 400 CS trajectories from five independent HF target orientations provide a complete description of the reactive processes in this system, including: non-charge-transfer scattering (NCTS), charge-transfer scattering (CTS), hydrogen fluoride dissociation (H-F D), and hydrogen rearrangement (HR). Several aspects of the reactions dynamics, such as mechanistic details and rainbow angles effects, are discussed. Differential and integral cross sections are evaluated via a novel CS formulation of those properties in conjunction with semiclassical techniques. The calculated total differential cross section shows an excellent agreement with available experimental results.

  4. Mathematical model with spatially uniform regulation explains long-range bidirectional transport of early endosomes in fungal hyphae.

    Science.gov (United States)

    Gou, Jia; Edelstein-Keshet, Leah; Allard, Jun

    2014-08-15

    In many cellular contexts, cargo is transported bidirectionally along microtubule bundles by dynein and kinesin-family motors. Upstream factors influence how individual cargoes are locally regulated, as well as how long-range transport is regulated at the whole-cell scale. Although the details of local, single-cargo bidirectional switching have been extensively studied, it remains to be elucidated how this results in cell-scale spatial organization. Here we develop a mathematical model of early endosome transport in Ustilago maydis. We demonstrate that spatiotemporally uniform regulation, with constant transition rates, results in cargo dynamics that is consistent with experimental data, including data from motor mutants. We find that microtubule arrays can be symmetric in plus-end distribution but asymmetric in binding-site distribution in a manner that affects cargo dynamics and that cargo can travel past microtubule ends in microtubule bundles. Our model makes several testable predictions, including secondary features of dynein and cargo distributions.

  5. Theoretical studies on nuclear spin selective quantum dynamics of non-linear molecules; Theoretische Untersuchung zur Quantendynamik der Kernspinisomere nicht-linearer Molekuele

    Energy Technology Data Exchange (ETDEWEB)

    Grohmann, Thomas

    2012-05-31

    In this thesis the wave packet dynamics of nuclear spin isomers of polyatomic molecules after interaction with static and time-dependent magnetic fields and moderate intense nonresonant laser pulses is investigated. In particular, the process of inducing (internal) molecular rotation as well as alignment of molecules by manipulating their rotational or rotational-torsional degrees of freedom is studied. In the first part of the thesis all theoretical concepts for identifying nuclear spin isomers and for describing their quantum dynamics will be discussed. Especially the symmetrization postulate and themolecular symmetry group will be introduced and illustrated for some examples of molecules. These concepts will be extended to the case of identifying nuclear spin isomers in the presence of an external field. In the second part it is shown for nitromethane that magnetic fields are able to induce unidirectional rotations in opposite directions for different nuclear spin isomers of molecules containing methyl groups if the dipolar interaction is included. Additionally, it is demonstrated that different nuclear spin isomers of a chemical compound may show different alignment after the interaction with a moderate intense laser pulse. As shown for the rigid symmetric top propadien and the rigid asymmetric tops ethene and analogues, distinct pairs of nuclear spin isomers show at certain points in time a complementary behavior: while one isomer is showing alignment the partner isomer is showing anti-alignment. Moreover, it is illustrated that not every nuclear spin isomer can be aligned equally efficient. The alignment of non-rigid molecules is considered as well. As an example for a molecule with feasible torsion in the electronic ground state, the alignment of diboron tetrafluoride is investigated. It becomes apparent that not only rotational but also the torsional dynamics of the molecules is nuclear spin selective; different nuclear spin isomers have at distinct points

  6. Global evaluation of ammonia bi-directional exchange

    Directory of Open Access Journals (Sweden)

    L. Zhu

    2015-02-01

    Full Text Available Bi-directional air–surface exchange of ammonia (NH3 has been neglected in many air quality models. In this study, we implement the bi-directional exchange of NH3 in the GEOS-Chem global chemical transport model. We also introduce an updated diurnal variability scheme for NH3 livestock emissions and evaluate the recently developed MASAGE_NH3 bottom up inventory. While updated diurnal variability improves comparison of modeled-to-hourly in situ measurements in the Southeastern US, NH3 concentrations decrease throughout the globe, up to 17 ppb in India and Southeastern China, with corresponding decreases in aerosol nitrate by up to 7 μg m−3. The ammonium (NH4+ soil pool in the bi-directional exchange model largely extends the NH3 lifetime in the atmosphere. Including bi-directional exchange generally increases NH3 gross emissions (7.1% and surface concentrations (up to 3.9 ppb throughout the globe in July, except in India and Southeastern China. In April and October, it decreases NH3 gross emissions in the Northern Hemisphere (e.g., 43.6% in April in China and increases NH3 gross emissions in the Southern Hemisphere. Bi-directional exchange does not largely impact NH4+ wet deposition overall. While bi-directional exchange is fundamentally a better representation of NH3 emissions from fertilizers, emissions from primary sources are still underestimated and thus significant model biases remain when compared to in situ measurements in the US. The adjoint of bi-directional exchange has also been developed for the GEOS-Chem model and is used to investigate the sensitivity of NH3 concentrations with respect to soil pH and fertilizer application rate. This study thus lays the groundwork for future inverse modeling studies to more directly constrain these physical processes rather than tuning bulk uni-directional NH3 emissions.

  7. Global evaluation of ammonia bi-directional exchange

    Science.gov (United States)

    Zhu, L.; Henze, D.; Bash, J.; Jeong, G.-R.; Cady-Pereira, K.; Shephard, M.; Luo, M.; Paulot, F.; Capps, S.

    2015-02-01

    Bi-directional air-surface exchange of ammonia (NH3) has been neglected in many air quality models. In this study, we implement the bi-directional exchange of NH3 in the GEOS-Chem global chemical transport model. We also introduce an updated diurnal variability scheme for NH3 livestock emissions and evaluate the recently developed MASAGE_NH3 bottom up inventory. While updated diurnal variability improves comparison of modeled-to-hourly in situ measurements in the Southeastern US, NH3 concentrations decrease throughout the globe, up to 17 ppb in India and Southeastern China, with corresponding decreases in aerosol nitrate by up to 7 μg m-3. The ammonium (NH4+) soil pool in the bi-directional exchange model largely extends the NH3 lifetime in the atmosphere. Including bi-directional exchange generally increases NH3 gross emissions (7.1%) and surface concentrations (up to 3.9 ppb) throughout the globe in July, except in India and Southeastern China. In April and October, it decreases NH3 gross emissions in the Northern Hemisphere (e.g., 43.6% in April in China) and increases NH3 gross emissions in the Southern Hemisphere. Bi-directional exchange does not largely impact NH4+ wet deposition overall. While bi-directional exchange is fundamentally a better representation of NH3 emissions from fertilizers, emissions from primary sources are still underestimated and thus significant model biases remain when compared to in situ measurements in the US. The adjoint of bi-directional exchange has also been developed for the GEOS-Chem model and is used to investigate the sensitivity of NH3 concentrations with respect to soil pH and fertilizer application rate. This study thus lays the groundwork for future inverse modeling studies to more directly constrain these physical processes rather than tuning bulk uni-directional NH3 emissions.

  8. Requirements for a Dynamic Solvent Extraction Module to Support Development of Advanced Technologies for the Recycle of Used Nuclear Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Jack Law; Veronica Rutledge; Candido Pereira; Jackie Copple; Kurt Frey; John Krebs; Laura Maggos; Kevin Nichols; Kent Wardle; Pratap Sadasivan; Valmor DeAlmieda; David Depaoli

    2011-06-01

    The Department of Energy's Nuclear Energy Advanced Modeling and Simulation (NEAMS) Program has been established to create and deploy next generation, verified and validated nuclear energy modeling and simulation capabilities for the design, implementation, and operation of future nuclear energy systems to improve the U.S. energy security. As part of the NEAMS program, Integrated Performance and Safety Codes (IPSC's) are being produced to significantly advance the status of modeling and simulation of energy systems beyond what is currently available to the extent that the new codes be readily functional in the short term and extensible in the longer term. The four IPSC areas include Safeguards and Separations, Reactors, Fuels, and Waste Forms. As part of the Safeguards and Separations (SafeSeps) IPSC effort, interoperable process models are being developed that enable dynamic simulation of an advanced separations plant. A SafeSepss IPSC 'toolkit' is in development to enable the integration of separation process modules and safeguards tools into the design process by providing an environment to compose, verify and validate a simulation application to be used for analysis of various plant configurations and operating conditions. The modules of this toolkit will be implemented on a modern, expandable architecture with the flexibility to explore and evaluate a wide range of process options while preserving their stand-alone usability. Modules implemented at the plant-level will initially incorporate relatively simple representations for each process through a reduced modeling approach. Final versions will incorporate the capability to bridge to subscale models to provide required fidelity in chemical and physical processes. A dynamic solvent extraction model and its module implementation are needed to support the development of this integrated plant model. As a stand-alone application, it will also support solvent development of extraction flowsheets

  9. Improvement of level-1 PSA computer code package - Modeling and analysis for dynamic reliability of nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Hoon; Baek, Sang Yeup; Shin, In Sup; Moon, Shin Myung; Moon, Jae Phil; Koo, Hoon Young; Kim, Ju Shin [Seoul National University, Seoul (Korea, Republic of); Hong, Jung Sik [Seoul National Polytechnology University, Seoul (Korea, Republic of); Lim, Tae Jin [Soongsil University, Seoul (Korea, Republic of)

    1996-08-01

    The objective of this project is to develop a methodology of the dynamic reliability analysis for NPP. The first year`s research was focused on developing a procedure for analyzing failure data of running components and a simulator for estimating the reliability of series-parallel structures. The second year`s research was concentrated on estimating the lifetime distribution and PM effect of a component from its failure data in various cases, and the lifetime distribution of a system with a particular structure. Computer codes for performing these jobs were also developed. The objectives of the third year`s research is to develop models for analyzing special failure types (CCFs, Standby redundant structure) that were nor considered in the first two years, and to complete a methodology of the dynamic reliability analysis for nuclear power plants. The analysis of failure data of components and related researches for supporting the simulator must be preceded for providing proper input to the simulator. Thus this research is divided into three major parts. 1. Analysis of the time dependent life distribution and the PM effect. 2. Development of a simulator for system reliability analysis. 3. Related researches for supporting the simulator : accelerated simulation analytic approach using PH-type distribution, analysis for dynamic repair effects. 154 refs., 5 tabs., 87 figs. (author)

  10. Image-based modeling reveals dynamic redistribution of DNA damage into nuclear sub-domains.

    Directory of Open Access Journals (Sweden)

    Sylvain V Costes

    2007-08-01

    Full Text Available Several proteins involved in the response to DNA double strand breaks (DSB form microscopically visible nuclear domains, or foci, after exposure to ionizing radiation. Radiation-induced foci (RIF are believed to be located where DNA damage occurs. To test this assumption, we analyzed the spatial distribution of 53BP1, phosphorylated ATM, and gammaH2AX RIF in cells irradiated with high linear energy transfer (LET radiation and low LET. Since energy is randomly deposited along high-LET particle paths, RIF along these paths should also be randomly distributed. The probability to induce DSB can be derived from DNA fragment data measured experimentally by pulsed-field gel electrophoresis. We used this probability in Monte Carlo simulations to predict DSB locations in synthetic nuclei geometrically described by a complete set of human chromosomes, taking into account microscope optics from real experiments. As expected, simulations produced DNA-weighted random (Poisson distributions. In contrast, the distributions of RIF obtained as early as 5 min after exposure to high LET (1 GeV/amu Fe were non-random. This deviation from the expected DNA-weighted random pattern can be further characterized by "relative DNA image measurements." This novel imaging approach shows that RIF were located preferentially at the interface between high and low DNA density regions, and were more frequent than predicted in regions with lower DNA density. The same preferential nuclear location was also measured for RIF induced by 1 Gy of low-LET radiation. This deviation from random behavior was evident only 5 min after irradiation for phosphorylated ATM RIF, while gammaH2AX and 53BP1 RIF showed pronounced deviations up to 30 min after exposure. These data suggest that DNA damage-induced foci are restricted to certain regions of the nucleus of human epithelial cells. It is possible that DNA lesions are collected in these nuclear sub-domains for more efficient repair.

  11. Image-Based Modeling Reveals Dynamic Redistribution of DNA Damageinto Nuclear Sub-Domains

    Energy Technology Data Exchange (ETDEWEB)

    Costes Sylvain V., Ponomarev Artem, Chen James L.; Nguyen, David; Cucinotta, Francis A.; Barcellos-Hoff, Mary Helen

    2007-08-03

    Several proteins involved in the response to DNA doublestrand breaks (DSB) f orm microscopically visible nuclear domains, orfoci, after exposure to ionizing radiation. Radiation-induced foci (RIF)are believed to be located where DNA damage occurs. To test thisassumption, we analyzed the spatial distribution of 53BP1, phosphorylatedATM, and gammaH2AX RIF in cells irradiated with high linear energytransfer (LET) radiation and low LET. Since energy is randomly depositedalong high-LET particle paths, RIF along these paths should also berandomly distributed. The probability to induce DSB can be derived fromDNA fragment data measured experimentally by pulsed-field gelelectrophoresis. We used this probability in Monte Carlo simulations topredict DSB locations in synthetic nuclei geometrically described by acomplete set of human chromosomes, taking into account microscope opticsfrom real experiments. As expected, simulations produced DNA-weightedrandom (Poisson) distributions. In contrast, the distributions of RIFobtained as early as 5 min after exposure to high LET (1 GeV/amu Fe) werenon-random. This deviation from the expected DNA-weighted random patterncan be further characterized by "relative DNA image measurements." Thisnovel imaging approach shows that RIF were located preferentially at theinterface between high and low DNA density regions, and were morefrequent than predicted in regions with lower DNA density. The samepreferential nuclear location was also measured for RIF induced by 1 Gyof low-LET radiation. This deviation from random behavior was evidentonly 5 min after irradiation for phosphorylated ATM RIF, while gammaH2AXand 53BP1 RIF showed pronounced deviations up to 30 min after exposure.These data suggest that DNA damage induced foci are restricted to certainregions of the nucleus of human epithelial cells. It is possible that DNAlesions are collected in these nuclear sub-domains for more efficientrepair.

  12. Nuclear and partonic dynamics in the EMC effect at Next-to-Next-to-Leading order

    CERN Document Server

    Tehrani, S Atashbar

    2014-01-01

    We study in details the parameterizations of the nuclear parton distributions at the next-to-next-to-leading order (NNLO) of $\\alpha_s$. In low $x$ and $Q_0^2$, we observe negative gluon distribution at this order which signals the saturation condition or the quark-gluon plasma condition. Our study also shows the gluon distribution at (NNLO) is less than next-to-leading order (NLO) of $\\alpha_s$, and the sea quark distribution at (NNLO) is larger than (NLO).

  13. Nuclear envelope dynamics during plant cell division suggest common mechanisms between kingdoms.

    Science.gov (United States)

    Graumann, Katja; Evans, David E

    2011-05-01

    Behaviour of the NE (nuclear envelope) during open mitosis has been explored extensively in metazoans, but lack of native markers has limited similar investigations in plants. In the present study, carried out using living synchronized tobacco BY-2 suspension cultures, the non-functional NE marker LBR (lamin B receptor)-GFP (green fluorescent protein) and two native, functional NE proteins, AtSUN1 [Arapidopsis thaliana SUN (Sad1/UNC84) 1] and AtSUN2, we provide evidence that the ER (endoplasmic reticulum)-retention theory for NE membranes is applicable in plants. We also observe two apparently unique plant features: location of the NE-membrane components in close proximity to chromatin throughout division, and spatially distinct reformation of the NE commencing at the chromatin surface facing the spindle poles and concluding at the surface facing the cell plate. Mobility of the proteins was investigated in the interphase NE, during NE breakdown and reformation, in the spindle membranes and the cell plate. A role for AtSUN2 in nuclear envelope breakdown is suggested.

  14. Charge order and low frequency spin dynamics in lanthanum cuprates revealed by Nuclear Magnetic Resonance

    Energy Technology Data Exchange (ETDEWEB)

    Grafe, H.J.; Vyalikh, A.; Vavilova, J.; Buchner, B. [IFW Dresden, Institute for Solid State Research, Dresden (Germany); Curro, N.J. [Department of Physics, University of California, Davis, CA (United States); Young, B.L. [Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan (China); Gu, G.D.; Hucker, M. [Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY (United States); Vavilova, J. [Kazan Zavoiskiy Physical-Technical Institute, Kazan (Russian Federation)

    2010-10-15

    We report detailed {sup 17}O, {sup 139}La, and {sup 63,65}Cu Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) measurements in a stripe ordered La{sub 1.875}Ba{sub 0.125}CuO{sub 4} single crystal and in oriented powder samples of La{sub 1.8-x}Eu{sub 0.2}Sr{sub x}CuO{sub 4}. We observe a partial wipe out of the {sup 17}O NMR intensity and a simultaneous drop of the {sup 17}O electric field gradient (EFG) at low temperatures where the spin stripe order sets in. In contrast, the {sup 63,65}Cu intensity is completely wiped out at the same temperature. The drop of the {sup 17}O quadrupole frequency is compatible with a charge stripe order. The {sup 17}O spin lattice relaxation rate shows a peak similar to that of the {sup 139}La, which is of magnetic origin. This peak is doping dependent and is maximal at x {approx} 1/8. (authors)

  15. Complex risk analysis for loss of electric power in liquid metal nuclear reactor by system dynamics (SD) method

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Tae Ho [Seoul National Univ. (Korea, Republic of). Dept. of Nuclear Engineering

    2012-07-15

    The power stabilization of the nuclear power plants (NPPs) is investigated in the aspect of the liquid metal coolant. The quantification of the risk analysis is performed by the system dynamics (SD) method which is processed by the feedback and accumulation complex algorithms. The Vensim software package is used for the simulations, which is supported by the Monte-Carlo method. There are 2 kinds of considerations as the economic and safety properties. The result shows the stability of the operations when the power can be decided. This shows the higher efficiency of the reactor. The failure frequency is 16/60 = 27%. In the event of Power Stabilized, the failure event is in the quite lower frequency rate. The commercial use of the reactor is important in the operations. (orig.)

  16. MMCT-mediated chromosome engineering technique applicable to functional analysis of lncRNA and nuclear dynamics.

    Science.gov (United States)

    Meguro-Horike, Makiko; Horike, Shin-Ichi

    2015-01-01

    Recent evidence implicated several long noncoding RNA (lncRNA) in gene expression in cis or trans through regulating the local chromosomal architecture. However, the mechanisms underlying the lncRNA mediated silencing of multiple genes remain unknown. We believe that Microcell Mediated Chromosome Transfer (MMCT) is a suitable approach for functional analysis of lncRNAs and nuclear dynamics. MMCT is a unique research technique that can be generally used to transfer a single chromosome from one mammalian cell to another. Transferred chromosomes can be stably maintained as functioning in the recipient cells. Since there is no size limit to introducing genomic locus, an approach using the chromosome transfer technique is suitable for functional analysis of a large chromosomal domain. Here we describe a general strategy of MMCT, applications of which have potential to be an alternative tool of existing gene delivery system.

  17. Molecular Dynamics Simulation of Lead Borate and Related Glasses in Multicomponent Systems for Low Melting Vitrification of Nuclear Wastes

    Energy Technology Data Exchange (ETDEWEB)

    Kato, S; Benino, Y; Nanba, T [Graduate School of Environmental Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530 (Japan); Sakida, S, E-mail: benino@cc.okayama-u.ac.jp [Environmental Management Center, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530 (Japan)

    2011-03-15

    Glasses based on lead oxide have excellent properties in general such as low melting point, high chemical durability and high stability of glassy form, which are suitable for the preservation of volatile nuclear wastes in a permanent vitrified form. In order to confirm the long-term performance of lead borate based glasses it is necessary to establish dissolution and diffusion processes based on a reliable model of the glass structure. In the present study molecular dynamics (MD) simulation of lead borate based glasses was carried out introducing a dummy negative point charge to reproduce asymmetric PbO{sub n} units. Parameters for the dummy charge were optimized based on the comparison between calculated radial distribution function and experimental one. Asymmetric coordination around Pb, for example trigonal bipyramid, was successfully reproduced in the MD simulated binary and ternary glass models. The simple model using the dummy charge was confirmed to be valid for further simulations of multicomponent glasses containing nuclear wastes and heavy elements.

  18. On The Potential of Dynamic Nuclear Polarization Enhanced Diamonds in Solid-State and Dissolution (13) C NMR Spectroscopy.

    Science.gov (United States)

    Bretschneider, Christian O; Akbey, Ümit; Aussenac, Fabien; Olsen, Greg L; Feintuch, Akiva; Oschkinat, Hartmut; Frydman, Lucio

    2016-09-01

    Dynamic nuclear polarization (DNP) is a versatile option to improve the sensitivity of NMR and MRI. This versatility has elicited interest for overcoming potential limitations of these techniques, including the achievement of solid-state polarization enhancement at ambient conditions, and the maximization of (13) C signal lifetimes for performing in vivo MRI scans. This study explores whether diamond's (13) C behavior in nano- and micro-particles could be used to achieve these ends. The characteristics of diamond's DNP enhancement were analyzed for different magnetic fields, grain sizes, and sample environments ranging from cryogenic to ambient temperatures, in both solution and solid-state experiments. It was found that (13) C NMR signals could be boosted by orders of magnitude in either low- or room-temperature solid-state DNP experiments by utilizing naturally occurring paramagnetic P1 substitutional nitrogen defects. We attribute this behavior to the unusually long electronic/nuclear spin-lattice relaxation times characteristic of diamond, coupled with a time-independent cross-effect-like polarization transfer mechanism facilitated by a matching of the nitrogen-related hyperfine coupling and the (13) C Zeeman splitting. The efficiency of this solid-state polarization process, however, is harder to exploit in dissolution DNP-enhanced MRI contexts. The prospects for utilizing polarized diamond approaching nanoscale dimensions for both solid and solution applications are briefly discussed.

  19. Modelling the local atomic structure of molybdenum in nuclear waste glasses with ab initio molecular dynamics simulations.

    Science.gov (United States)

    Konstantinou, Konstantinos; Sushko, Peter V; Duffy, Dorothy M

    2016-09-21

    The nature of chemical bonding of molybdenum in high level nuclear waste glasses has been elucidated by ab initio molecular dynamics simulations. Two compositions, (SiO2)57.5-(B2O3)10-(Na2O)15-(CaO)15-(MoO3)2.5 and (SiO2)57.3-(B2O3)20-(Na2O)6.8-(Li2O)13.4-(MoO3)2.5, were considered in order to investigate the effect of ionic and covalent components on the glass structure and the formation of the crystallisation precursors (Na2MoO4 and CaMoO4). The coordination environments of Mo cations and the corresponding bond lengths calculated from our model are in excellent agreement with experimental observations. The analysis of the first coordination shell reveals two different types of molybdenum host matrix bonds in the lithium sodium borosilicate glass. Based on the structural data and the bond valence model, we demonstrate that the Mo cation can be found in a redox state and the molybdate tetrahedron can be connected with the borosilicate network in a way that inhibits the formation of crystalline molybdates. These results significantly extend our understanding of bonding in Mo-containing nuclear waste glasses and demonstrate that tailoring the glass composition to specific heavy metal constituents can facilitate incorporation of heavy metals at high concentrations.

  20. Low-temperature dynamic nuclear polarization with helium-cooled samples and nitrogen-driven magic-angle spinning.

    Science.gov (United States)

    Thurber, Kent; Tycko, Robert

    2016-03-01

    We describe novel instrumentation for low-temperature solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS), focusing on aspects of this instrumentation that have not been described in detail in previous publications. We characterize the performance of an extended interaction oscillator (EIO) microwave source, operating near 264 GHz with 1.5 W output power, which we use in conjunction with a quasi-optical microwave polarizing system and a MAS NMR probe that employs liquid helium for sample cooling and nitrogen gas for sample spinning. Enhancement factors for cross-polarized (13)C NMR signals in the 100-200 range are demonstrated with DNP at 25K. The dependences of signal amplitudes on sample temperature, as well as microwave power, polarization, and frequency, are presented. We show that sample temperatures below 30K can be achieved with helium consumption rates below 1.3 l/h. To illustrate potential applications of this instrumentation in structural studies of biochemical systems, we compare results from low-temperature DNP experiments on a calmodulin-binding peptide in its free and bound states.

  1. Low-temperature dynamic nuclear polarization with helium-cooled samples and nitrogen-driven magic-angle spinning

    Science.gov (United States)

    Thurber, Kent; Tycko, Robert

    2016-03-01

    We describe novel instrumentation for low-temperature solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS), focusing on aspects of this instrumentation that have not been described in detail in previous publications. We characterize the performance of an extended interaction oscillator (EIO) microwave source, operating near 264 GHz with 1.5 W output power, which we use in conjunction with a quasi-optical microwave polarizing system and a MAS NMR probe that employs liquid helium for sample cooling and nitrogen gas for sample spinning. Enhancement factors for cross-polarized 13C NMR signals in the 100-200 range are demonstrated with DNP at 25 K. The dependences of signal amplitudes on sample temperature, as well as microwave power, polarization, and frequency, are presented. We show that sample temperatures below 30 K can be achieved with helium consumption rates below 1.3 l/h. To illustrate potential applications of this instrumentation in structural studies of biochemical systems, we compare results from low-temperature DNP experiments on a calmodulin-binding peptide in its free and bound states.

  2. Ultrafast nuclear dynamics in halomethanes studied with time-resolved Coulomb explosion imaging and channel-selective Fourier spectroscopy

    Science.gov (United States)

    Malakar, Y.; Kaderiya, B.; Pearson, W. L.; Ziaee, F.; Kanaka Raju, P.; Zohrabi, M.; Jensen, K.; Rajput, J.; Ben-Itzhak, I.; Rolles, D.; Rudenko, A.

    2016-05-01

    Halomethanes have recently attracted considerable attention since they often serve as prototype systems for laser-controlled chemistry (e.g., selective bond breaking or concerted elimination reactions), and are important molecules in atmospheric chemistry. Here we combine a femtosecond laser pump-probe setup with coincident 3D ion momentum imaging apparatus to study strong-field induced nuclear dynamics in methane and several of its halogenated derivatives (CH3 I, CH2 I2, CH2 ICl). We apply a time-resolved Coulomb explosion imaging technique to map the nuclear motion on both, bound and continuum potential surfaces, disentangle different fragmentation pathways and, for halogenated molecules, observe clear signatures of vibrational wave packets in neutral or ionized states. Channel-selective and kinetic-energy resolved Fourier analysis of these data allows for unique identification of different electronic states and vibrational modes responsible for a particular structure. Supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U. S. DOE. K. R. P. and W. L. P. supported by NSF Award No. IIA-143049. K.J. supported by the NSF-REU Grant No. PHYS-1461251.

  3. Probing nuclear dynamics and architecture using single-walled carbon nanotubes

    Science.gov (United States)

    Jung, Yoon; Li, Junang; Fakhri, Nikta

    Chromatin is a multiscale dynamic architecture that acts as a template for many biochemical processes such as transcription and DNA replication. Recent developments such as Hi-C technology enable an identification of chromatin interactions across an entire genome. However, a single cell dynamic view of chromatin organization is far from understood. We discuss a new live cell imaging technique to probe the dynamics of the nucleus at a single cell level using single-walled carbon nanotubes (SWNTs). SWNTs are non-perturbing rigid rods (diameter of 1 nm and length of roughly 100 nm) that fluoresce in the near infrared region. Due to their high aspect ratio, they can diffuse in tight spaces and report on the architecture and dynamics of the nucleoplasm. We develop 3D imaging and tracking of SWNTs in the volume of the nucleus using double helix point spread function microscopy (DH-PSF) and discuss the capabilities of the DH-PSF for inferring the 3D orientation of nanotubes based on vectorial diffraction theory.

  4. Nuclear Engineering Computer Modules: Reactor Dynamics, RD-1 and RD-2.

    Science.gov (United States)

    Onega, Ronald J.

    The objective of the Reactor Dynamics Module, RD-1, is to obtain the kinetics equation without feedback and solve the kinetics equations numerically for one to six delayed neutron groups for time varying reactivity insertions. The computer code FUMOKI (Fundamental Mode Kinetics) will calculate the power as a function of time for either uranium or…

  5. Dynamic modelling of radionuclide uptake by marine biota: application to the Fukushima nuclear power plant accident.

    Science.gov (United States)

    Vives i Batlle, Jordi

    2016-01-01

    The dynamic model D-DAT was developed to study the dynamics of radionuclide uptake and turnover in biota and sediments in the immediate aftermath of the Fukushima accident. This dynamics is determined by the interplay between the residence time of radionuclides in seawater/sediments and the biological half-lives of elimination by the biota. The model calculates time-variable activity concentration of (131)I, (134)Cs, (137)Cs and (90)Sr in seabed sediment, fish, crustaceans, molluscs and macroalgae from surrounding activity concentrations in seawater, with which to derive internal and external dose rates. A central element of the model is the inclusion of dynamic transfer of radionuclides to/from sediments by factorising the depletion of radionuclides adsorbed onto suspended particulates, molecular diffusion, pore water mixing and bioturbation, represented by a simple set of differential equations coupled with the biological uptake/turnover processes. In this way, the model is capable of reproducing activity concentration in sediment more realistically. The model was used to assess the radiological impact of the Fukushima accident on marine biota in the acute phase of the accident. Sediment and biota activity concentrations are within the wide range of actual monitoring data. Activity concentrations in marine biota are thus shown to be better calculated by a dynamic model than with the simpler equilibrium approach based on concentration factors, which tends to overestimate for the acute accident period. Modelled dose rates from external exposure from sediment are also significantly below equilibrium predictions. The model calculations confirm previous studies showing that radioactivity levels in marine biota have been generally below the levels necessary to cause a measurable effect on populations. The model was used in mass-balance mode to calculate total integrated releases of 103, 30 and 3 PBq for (131)I, (137)Cs and (90)Sr, reasonably in line with previous

  6. Electron and nuclear dynamics of molecular clusters in ultraintense laser fields. IV. Coulomb explosion of molecular heteroclusters.

    Science.gov (United States)

    Last, Isidore; Jortner, Joshua

    2004-11-01

    In this paper we present a theoretical and computational study of the temporal dynamics and energetics of Coulomb explosion of (CD4)(n) and (CH4)(n) (n=55-4213) molecular heteroclusters in ultraintense (I=10(16)-10(19) W cm(-2)) laser fields, addressing the manifestation of electron dynamics, together with nuclear energetic and kinematic effects on the heterocluster Coulomb instability. The manifestations of the coupling between electron and nuclear dynamics were explored by molecular dynamics simulations for these heteroclusters coupled to Gaussian laser fields (pulse width tau=25 fs), elucidating outer ionization dynamics, nanoplasma screening effects (being significant for Icharges and masses. Nonuniform heterocluster Coulomb explosion (eta >1) manifests an overrun effect of the light ions relative to the heavy ions, exhibiting the expansion of two spatially separated subclusters, with the light ions forming the outer subcluster at the outer edge of the spatial distribution. Important features of the energetics of heterocluster Coulomb explosion originate from energetic triggering effects of the driving of the light ions by the heavy ions (C(4+) for I=10(17)-10(18) W cm(-2) and C(6+) for I=10(19) W cm(-2)), as well as for kinematic effects. Based on the CVI assumption, scaling laws for the cluster size (radius R(0)) dependence of the energetics of uniform Coulomb explosion of heteroclusters (eta=1) were derived, with the size dependence of the average (E(j,av)) and maximal (E(j,M)) ion energies being E(j,av)=aR(0) (2) and E(j,M)=(5a/3)R(0) (2), as well as for the ion energy distributions P(E(j)) proportional to E(j) (1/2); E(j)1) result in an isotope effect, predicting the enhancement (by 9%-11%) of E(H,av) for Coulomb explosion of (C(4+)H(4) (+))(eta) (eta=3) relative to E(D,av) for Coulomb explosion of (C(4+)D(4) (+))(eta) (eta=1.5), with the isotope effect being determined by the ratio of the kinematic parameters for the pair of Coulomb exploding clusters

  7. Compartmental analysis of dynamic nuclear medicine data: regularization procedure and application to physiology

    CERN Document Server

    Fabrice, Delbary

    2016-01-01

    Compartmental models based on tracer mass balance are extensively used in clinical and pre-clinical nuclear medicine in order to obtain quantitative information on tracer metabolism in the biological tissue. This paper is the second of a series of two that deal with the problem of tracer coefficient estimation via compartmental modelling in an inverse problem framework. While the previous work was devoted to the discussion of identifiability issues for 2, 3 and n-dimension compartmental systems, here we discuss the problem of numerically determining the tracer coefficients by means of a general regularized Multivariate Gauss Newton scheme. In this paper, applications concerning cerebral, hepatic and renal functions are considered, involving experimental measurements on FDG-PET data on different set of murine models.

  8. Bulk nuclear properties from dynamical description of heavy-ion collisions

    Science.gov (United States)

    Hong, Jun

    Mapping out the equation of state (EOS) of nuclear matter is a long standing problem in nuclear physics. Both experimentalists and theoretical physicists spare no effort in improving understanding of the EOS. In this thesis, we examine observables sensitive to the EOS within the pBUU transport model based on the Boltzmann equation. By comparing theoretical predictions with experimental data, we arrive at new constraints for the EOS. Further we propose novel promising observables for analysis of future experimental data. One set of observables that we examine within the pBUU model are pion yields. First, we find that net pion yields in central heavy-ion collisions (HIC) are strongly sensitive to the momentum dependence of the isoscalar nuclear mean field. We reexamine the momentum dependence that is assumed in the Boltzmann equation model for the collisions and optimize that dependence to describe the FOPI measurements of pion yields from the Au+Au collisions at different beam energies. Alas such optimized dependence yields a somewhat weaker baryonic elliptic flow than seen in measurements. Subsequently, we use the same pBUU model to generate predictions for baryonic elliptic flow observable in HIC, while varying the incompressibility of nuclear matter. In parallel, we test the sensitivity of pion multiplicity to the density dependence of EOS, and in particular to incompressibility, and optimize that dependence to describe both the elliptic flow and pion yields. Upon arriving at acceptable regions of density dependence of pressure and energy, we compare our constraints on EOS with those recently arrived at by the joint experiment and theory effort FOPI-IQMD. We should mention that, for the more advanced observables from HIC, there remain discrepancies of up to 30%, depending on energy, between the theory and experiment, indicating the limitations of the transport theory. Next, we explore the impact of the density dependence of the symmetry energy on observables

  9. Dynamic friction and wear of a solid film lubricant during radiation exposure in a nuclear reactor

    Science.gov (United States)

    Jacobson, T. P.

    1972-01-01

    The effect of nuclear reactor radiation on the performance of a solid film lubricant was studied. The film consisted of molybdenum disulfide and graphite in a sodium silicate binder. Radiation levels of fast neutrons (E or = 1 MeV) were fluxed up to 3.5 times 10 to the 12th power n/sq cm-sec (intensity) and fluences up to 2 times 10 to the 18th power n/sq cm (total exposure). Coating wear lives were much shorter and friction coefficients higher in a high flux region of the reactor than in a low flux region. The amount of total exposure did not affect lubrication behavior as severely as the radiation intensity during sliding.

  10. The baryon-decuplet in the chiral dynamics of Lambda-hyperons in nuclear matter

    CERN Document Server

    Camalich, J M

    2006-01-01

    We study the long range part of the $\\Lambda$-hyperon optical potential in nuclei using Quantum Many Body techniques and flavor-SU(3) Chiral Lagrangians as starting point. More precisely, we study the contributions to the $\\Lambda$-hyperon optical potential due to the long-range two-pion exchange, with $\\Sigma$ and $\\Sigma^*$ baryons in the internal baryonic lines and considering Nh and $\\Delta$h excitations. We also consider the contribution to the spin-orbit potentials that comes out from these terms. Our results support a natural explanation of the smallness of the $\\Lambda$-nuclear spin-orbit interaction and shows the importance of the $\\Sigma^*$ and $\\Delta$ degrees of freedom for the hyperon-nucleus interactions.

  11. Time-dependent density functional studies of nuclear quantum dynamics in large amplitudes

    CERN Document Server

    Wen, Kai; Fang, Ni; Nakatsukasa, Takashi

    2015-01-01

    The time-dependent density functional theory (TDDFT) provides a unified description of the structure and reaction. The linear approximation leads to the random-phase approximation (RPA) which is capable of describing a variety of collective motion in a harmonic regime. Beyond the linear regime, we present applications of the TDDFT to nuclear fusion and fission reaction. In particular, the extraction of the internuclear potential and the inertial mass parameter is performed using two different methods. A fusion hindrance mechanism for heavy systems is investigated from the microscopic point of view. The canonical collective variables are determined by the adiabatic self-consistent collective coordinate method. Preliminary results of the spontaneous fission path, the potential, and the collective mass parameter are shown for 8Be --> alpha+alpha.

  12. Structure, Dynamics, and Assembly of Filamentous Bacteriophages by Nuclear Magnetic Resonance Spectroscopy

    Science.gov (United States)

    Opella, Stanley J.; Zeri, Ana Carolina; Park, Sang Ho

    2008-05-01

    Filamentous bacteriophages serve as model systems for the development and implementation of spectroscopic methods suitable for biological supramolecular assemblies. Not only are their coat proteins small and readily prepared in the laboratory, but they also have two primary roles as membrane proteins and as the principal structural element of the virus particles. As a bacterial system, they are readily labeled with stable isotopes, and this has opened possibilities for the many nuclear magnetic resonance (NMR) studies described in this review. In particular, solid-state NMR of aligned samples has been used to determine the three-dimensional structures of both the membrane-bound forms of coat proteins in phospholipid bilayers and structural forms in virus particles, which has led to an analysis of the assembly mechanism for virus particles as they are extruded through the cell membrane.

  13. Dark Matter RNA: an Intelligent Scaffold for the Dynamic Regulation of the Nuclear Information Landscape

    Directory of Open Access Journals (Sweden)

    Georges eSt. Laurent

    2012-04-01

    Full Text Available Perhaps no other topic in contemporary genomics has inspired such diverse viewpoints as the 95+% of the genome, previously known as junk DNA, that does not code for proteins. Here, we present a theory in which dark matter RNA plays a role in the generation of a landscape of spatial micro-domains coupled to the information signaling matrix of the nuclear landscape. Within and between these microdomains, dark matter RNAs additionally function to tether RNA interacting proteins and complexes of many different types, and by doing so, allow for a higher performance of the various processes requiring them at ultra-fast rates. This improves signal to noise characteristics of RNA processing, trafficking, and epigenetic signaling, where competition and differential RNA binding among proteins drives the computational decisions inherent in regulatory events.

  14. {sup 23}Na nuclear magnetic resonance study of the structure and dynamic of natrolite

    Energy Technology Data Exchange (ETDEWEB)

    Paczwa, Mateusz; Olszewski, Marcin; Sergeev, Nikolaj [Szczecin Univ. (Poland). Inst. of Physics; Sapiga, Aleksej A.; Sapiga, Aleksej V. [Taurida National V.I. Vernadsky Univ., Simferopol, Crimea (Ukraine)

    2015-07-01

    The temperature dependences of nuclear magnetic resonance (NMR) and magic angle spinning (MAS) NMR spectra of {sup 23}Na nuclei in natrolite (Na{sub 2}Al{sub 2}Si{sub 3}O{sub 10} . 2H{sub 2}O) have been studied. The temperature dependences of the spin-lattice relaxation times T{sub 1} in natrolite have also been studied. It has been shown that the spin-lattice relaxation of the {sup 23}Na is governed by the electric quadrupole interaction with the crystal electric field gradients modulated by translational motion of H{sub 2}O molecules in the natrolite pores. The dipolar interactions with paramagnetic impurities become significant as a relaxation mechanism of the {sup 23}Na nuclei only at low temperature (<270 K).

  15. Bidirectional promoters of insects: genome-wide comparison, evolutionary implication and influence on gene expression.

    Science.gov (United States)

    Behura, Susanta K; Severson, David W

    2015-01-30

    Bidirectional promoters are widespread in insect genomes. By analyzing 23 insect genomes we show that the frequency of bidirectional gene pairs varies according to genome compactness and density of genes among the species. The density of bidirectional genes expected based on number of genes per megabase of genome explains the observed density suggesting that bidirectional pairing of genes may be due to random event. We identified specific transcription factor binding motifs that are enriched in bidirectional promoters across insect species. Furthermore, we observed that bidirectional promoters may act as transcriptional hotspots in insect genomes where protein coding genes tend to aggregate in significantly biased (p promoters. Natural selection seems to have an association with the extent of bidirectionality of genes among the species. The rate of non-synonymous-to-synonymous changes (dN/dS) shows a second-order polynomial distribution with bidirectionality between species indicating that bidirectionality is dependent upon evolutionary pressure acting on the genomes. Analysis of genome-wide microarray expression data of multiple insect species suggested that bidirectionality has a similar association with transcriptome variation across species. Furthermore, bidirectional promoters show significant association with correlated expression of the divergent gene pairs depending upon their motif composition. Analysis of gene ontology showed that bidirectional genes tend to have a common association with functions related to "binding" (including ion binding, nucleotide binding and protein binding) across genomes. Such functional constraint of bidirectional genes may explain their widespread persistence in genome of diverse insect species.

  16. Piezoelectric power converter with bi-directional power transfer

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a bi-directional piezoelectric power converter com¬ prising a piezoelectric transformer. The piezoelectric transformer comprises an input electrode electrically coupled to a primary section of the piezoelectric transformer and an output electrode electrically...... coupled to an output section of the piezoelectric transformer to provide a transformer output signal. A bi-directional switching circuit is coupled between the output electrode and a DC or AC output voltage of the power converter. Forward and reverse current conducting periods of the bi......, a reverse current is conducted through the bi-directional switching circuit from the DC or AC output voltage to the output electrode to discharge the DC or AC output voltage and return power to the primary section of the piezoelectric transformer....

  17. Socio-Hydrology: Conceptual and Methodological Challenges in the Bidirectional Coupling of Human and Water Systems

    Science.gov (United States)

    Scott, C. A.

    2014-12-01

    This presentation reviews conceptual advances in the emerging field of socio-hydrology that focuses on coupled human and water systems. An important current challenge is how to better couple the bidirectional influences between human and water systems, which lead to emergent dynamics. The interactions among (1) the structure and dynamics of systems with (2) human values and norms lead to (3) outcomes, which in turn influence subsequent interactions. Human influences on hydrological systems are relatively well understood, chiefly resulting from developments in the field of water resources. The ecosystem-service concept of cultural value has expanded understanding of decision-making beyond economic rationality criteria. Hydrological impacts on social processes are less well developed conceptually, but this is changing with growing attention to vulnerability, adaptation, and resilience, particularly in the face of climate change. Methodological limitations, especially in characterizing the range of human responses to hydrological events and drivers, still pose challenges to modeling bidirectional human-water influences. Evidence from multiple case studies, synthesized in more broadly generic syndromes, helps surmount these methodological limitations and offers the potential to improve characterization and quantification of socio-hydrological systems.

  18. Time delay control for fuel cells with bidirectional DC/DC converter and battery

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y.B. [Mechanical Engineering Department, Chonnam National University, Gwangju (Korea); Kang, S.J. [Mechatronics Engineering Department, Korea Polytechnic College V, Gwangju (Korea)

    2010-08-15

    Transient behavior is a key property in the vehicular application of proton exchange membrane (PEM) fuel cells. A better control technology is constructed to increase the transient performance of PEM fuel cells. A steady-state isothermal analytical fuel cell model is constructed to analyze mass transfer and water transport in the membrane. To prevent the starvation of air in the PEM fuel cell, time delay control is used to regulate the optimum stoichiometric amount of oxygen, although dynamic fluctuations exist in the PEM fuel cell power. A bidirectional DC/DC converter connects the battery to the DC link to manage the power distribution between the fuel cell and the battery. Dynamic evolution control (DEC) allows for adequate pulse-width modulation (PWM) control of the bidirectional DC/DC converter with fast response. Matlab/Simulink/Simpower simulation is performed to validate the proposed methodology, increase the transient performance of the PEM fuel cell system and satisfy the requirement of energy management. (author)

  19. Nuclear Magnetic Resonance Investigation of Dynamics in Poly(Ethylene Oxide) Based Lithium Polyether-ester-sulfonate Ionomers

    Energy Technology Data Exchange (ETDEWEB)

    Roach, David J.; Dou, Shichen; Colby, Ralph H.; Mueller, Karl T.

    2012-01-07

    Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies of both the polymer and lithium ions in the lower ion content samples indicate that the polymer segmental motion and lithium ion hopping motion are correlated even though their respective correlation times differ significantly. A divergent trend is observed for correlation times and activation energies of the highest ion content sample due to the presence of ionic aggregation. Details about the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments.

  20. Vibrational circular dichroism from ab initio molecular dynamics and nuclear velocity perturbation theory in the liquid phase

    Science.gov (United States)

    Scherrer, Arne; Vuilleumier, Rodolphe; Sebastiani, Daniel

    2016-08-01

    We report the first fully ab initio calculation of dynamical vibrational circular dichroism spectra in the liquid phase using nuclear velocity perturbation theory (NVPT) derived electronic currents. Our approach is rigorous and general and thus capable of treating weak interactions of chiral molecules as, e.g., chirality transfer from a chiral molecule to an achiral solvent. We use an implementation of the NVPT that is projected along the dynamics to obtain the current and magnetic dipole moments required for accurate intensities. The gauge problem in the liquid phase is resolved in a twofold approach. The electronic expectation values are evaluated in a distributed origin gauge, employing maximally localized Wannier orbitals. In a second step, the gauge invariant spectrum is obtained in terms of a scaled molecular moments, which allows to systematically include solvent effects while keeping a significant signal-to-noise ratio. We give a thorough analysis and discussion of this choice of gauge for the liquid phase. At low temperatures, we recover the established double harmonic approximation. The methodology is applied to chiral molecules ((S)-d2-oxirane and (R)-propylene-oxide) in the gas phase and in solution. We find an excellent agreement with the theoretical and experimental references, including the emergence of signals due to chirality transfer from the solute to the (achiral) solvent.

  1. Dynamical ejecta from precessing neutron star-black hole mergers with a hot, nuclear-theory based equation of state

    CERN Document Server

    Foucart, Francois; Brege, Wyatt; Duez, Matthew D; Kasen, Daniel; Hemberger, Daniel A; Kidder, Lawrence E; Pfeiffer, Harald P; Scheel, Mark A

    2016-01-01

    Neutron star-black hole binaries are among the strongest sources of gravitational waves detectable by current observatories. They can also power bright electromagnetic signals (gamma-ray bursts, kilonovae), and may be a significant source of production of r-process nuclei. A misalignment of the black hole spin with respect to the orbital angular momentum leads to precession of that spin and of the orbital plane, and has a significant effect on the properties of the post-merger remnant and of the material ejected by the merger. We present a first set of simulations of precessing neutron star-black hole mergers using a hot, composition dependent, nuclear-theory based equation of state (DD2). We show that the mass of the remnant and of the dynamical ejecta are broadly consistent with the result of simulations using simpler equations of state, while differences arise when considering the dynamics of the merger and the velocity of the ejecta. We show that the latter can easily be understood from assumptions about ...

  2. Vibrational circular dichroism from ab initio molecular dynamics and nuclear velocity perturbation theory in the liquid phase.

    Science.gov (United States)

    Scherrer, Arne; Vuilleumier, Rodolphe; Sebastiani, Daniel

    2016-08-28

    We report the first fully ab initio calculation of dynamical vibrational circular dichroism spectra in the liquid phase using nuclear velocity perturbation theory (NVPT) derived electronic currents. Our approach is rigorous and general and thus capable of treating weak interactions of chiral molecules as, e.g., chirality transfer from a chiral molecule to an achiral solvent. We use an implementation of the NVPT that is projected along the dynamics to obtain the current and magnetic dipole moments required for accurate intensities. The gauge problem in the liquid phase is resolved in a twofold approach. The electronic expectation values are evaluated in a distributed origin gauge, employing maximally localized Wannier orbitals. In a second step, the gauge invariant spectrum is obtained in terms of a scaled molecular moments, which allows to systematically include solvent effects while keeping a significant signal-to-noise ratio. We give a thorough analysis and discussion of this choice of gauge for the liquid phase. At low temperatures, we recover the established double harmonic approximation. The methodology is applied to chiral molecules ((S)-d2-oxirane and (R)-propylene-oxide) in the gas phase and in solution. We find an excellent agreement with the theoretical and experimental references, including the emergence of signals due to chirality transfer from the solute to the (achiral) solvent.

  3. Dynamical ejecta from precessing neutron star-black hole mergers with a hot, nuclear-theory based equation of state

    Science.gov (United States)

    Foucart, F.; Desai, D.; Brege, W.; Duez, M. D.; Kasen, D.; Hemberger, D. A.; Kidder, L. E.; Pfeiffer, H. P.; Scheel, M. A.

    2017-02-01

    Neutron star-black hole binaries are among the strongest sources of gravitational waves detectable by current observatories. They can also power bright electromagnetic signals (gamma-ray bursts, kilonovae), and may be a significant source of production of r-process nuclei. A misalignment of the black hole spin with respect to the orbital angular momentum leads to precession of that spin and of the orbital plane, and has a significant effect on the properties of the post-merger remnant and of the material ejected by the merger. We present a first set of simulations of precessing neutron star-black hole mergers using a hot, composition dependent, nuclear-theory based equation of state (DD2). We show that the mass of the remnant and of the dynamical ejecta are broadly consistent with the result of simulations using simpler equations of state, while differences arise when considering the dynamics of the merger and the velocity of the ejecta. We show that the latter can easily be understood from assumptions about the composition of low-density, cold material in the different equations of state, and propose an updated estimate for the ejecta velocity which takes those effects into account. We also present an updated mesh-refinement algorithm which allows us to improve the numerical resolution used to evolve neutron star-black hole mergers.

  4. Bidirectional communication using delay coupled chaotic directly modulated semiconductor lasers

    Indian Academy of Sciences (India)

    Bindu M Krishna; Manu P John; V M Nandakumaran

    2010-02-01

    Chaotic synchronization of two directly modulated semiconductor lasers with negative delayed optoelectronic feedback is investigated and this scheme is found to be useful for efficient bidirectional communication between the lasers. A symmetric bidirectional coupling is identified as a suitable method for isochronal synchronization of such lasers. The optimum values of coupling and feedback strength that can provide maximum quality of synchronization are identified. This method is successfully employed for encoding/decoding both analog and digital messages. The importance of a symmetric coupling is demonstrated by studying the variation of decoding efficiency with respect to asymmetric coupling.

  5. High Efficiency Bi-Directional Converter Used For Renewable System

    Directory of Open Access Journals (Sweden)

    M. Desal Raja

    2014-02-01

    Full Text Available This paper presents an Isolated bi-directional converter for renewable system. Voltage stress and current stress was decreses in switches. Power flows in both side. The proposed converter three phase ac voltage to dc voltage, dc voltage to three phase a.c voltage and synchronous the two voltage source. Silicon carbide diodes and bi-directional switches Mosfet’s are used for decreases the switching loss. LC Series resonant converter connected to the high efficiency. This converter power conversion control by the output voltage information.

  6. Comparison of the Beckmann model with bidirectional reflectance measurements.

    Science.gov (United States)

    Smith, T. F.; Hering, R. G.

    1973-01-01

    The Beckmann model is compared with recently reported bidirectional reflectance measurements. Comparisons revealed that monochromatic specular and bidirectional reflectance measurements are not adequately described by corresponding results evaluated from the model using mechanically acquired surface roughness parameters (rms height and rms slope). Significant improvement between measurements and predictions of the model is observed when optically acquired surface roughness parameters are used. Specular reflectance measurements for normal to intermediate polar angles of incidence are adequately represented by the model provided values of optical roughness multiplied by cosine of polar angle of incidence are less than 27 times average optical rms slope.

  7. Dissolution Dynamic Nuclear Polarization of Non-Self-Glassing Agents: Spectroscopy and Relaxation of Hyperpolarized [1-13C]Acetate

    DEFF Research Database (Denmark)

    Flori, Alessandra; Liserani, Matteo; Bowen, Sean

    2015-01-01

    The intrinsic physicochemical properties of the sample formulation are the key factors for efficient hyperpolarization through dissolution dynamic nuclear polarization (dissolution-DNP). We provide a comprehensive characterization of the DNP process for Na-[1-13C]acetate selected as a model for non...

  8. High-Speed Optical Local Access Network System Using Bi-Directional Polarization Multiplexing

    Institute of Scientific and Technical Information of China (English)

    Mitsuru Miyauchi; Yanjun Sun

    2003-01-01

    A high-speed and economical optical local access network system is proposed where bi-directional polarization multiplexing is applied to a bi-directional transmission. Experimental results using a prototype system confirmlow optical loss and environmental stabilities.

  9. High-Speed Optical Local Access Network System Using Bi-Directional Polarization Multiplexing

    Institute of Scientific and Technical Information of China (English)

    Mitsuru; Miyauchi; Yanjun; Sun

    2003-01-01

    A high-speed and economical optical local access network system is proposed where bi-directional polarization multiplexing is applied to a bi-directional transmission. Experimental results using a prototype system confirm low optical loss and environmental stabilities.

  10. The molecular mechanism of bisphenol A (BPA as an endocrine disruptor by interacting with nuclear receptors: insights from molecular dynamics (MD simulations.

    Directory of Open Access Journals (Sweden)

    Lanlan Li

    Full Text Available Bisphenol A (BPA can interact with nuclear receptors and affect the normal function of nuclear receptors in very low doses, which causes BPA to be one of the most controversial endocrine disruptors. However, the detailed molecular mechanism about how BPA interferes the normal function of nuclear receptors is still undiscovered. Herein, molecular dynamics simulations were performed to explore the detailed interaction mechanism between BPA with three typical nuclear receptors, including hERα, hERRγ and hPPARγ. The simulation results and calculated binding free energies indicate that BPA can bind to these three nuclear receptors. The binding affinities of BPA were slightly lower than that of E2 to these three receptors. The simulation results proved that the binding process was mainly driven by direct hydrogen bond and hydrophobic interactions. In addition, structural analysis suggested that BPA could interact with these nuclear receptors by mimicking the action of natural hormone and keeping the nuclear receptors in active conformations. The present work provided the structural evidence to recognize BPA as an endocrine disruptor and would be important guidance for seeking safer substitutions of BPA.

  11. Reduced stability and increased dynamics in the human proliferating cell nuclear antigen (PCNA relative to the yeast homolog.

    Directory of Open Access Journals (Sweden)

    Alfredo De Biasio

    Full Text Available Proliferating Cell Nuclear Antigen (PCNA is an essential factor for DNA replication and repair. PCNA forms a toroidal, ring shaped structure of 90 kDa by the symmetric association of three identical monomers. The ring encircles the DNA and acts as a platform where polymerases and other proteins dock to carry out different DNA metabolic processes. The amino acid sequence of human PCNA is 35% identical to the yeast homolog, and the two proteins have the same 3D crystal structure. In this report, we give evidence that the budding yeast (sc and human (h PCNAs have highly similar structures in solution but differ substantially in their stability and dynamics. hPCNA is less resistant to chemical and thermal denaturation and displays lower cooperativity of unfolding as compared to scPCNA. Solvent exchange rates measurements show that the slowest exchanging backbone amides are at the β-sheet, in the structure core, and not at the helices, which line the central channel. However, all the backbone amides of hPCNA exchange fast, becoming undetectable within hours, while the signals from the core amides of scPCNA persist for longer times. The high dynamics of the α-helices, which face the DNA in the PCNA-loaded form, is likely to have functional implications for the sliding of the PCNA ring on the DNA since a large hole with a flexible wall facilitates the establishment of protein-DNA interactions that are transient and easily broken. The increased dynamics of hPCNA relative to scPCNA may allow it to acquire multiple induced conformations upon binding to its substrates enlarging its binding diversity.

  12. Adenovirus replication is coupled with the dynamic properties of the PML nuclear structure.

    Science.gov (United States)

    Doucas, V; Ishov, A M; Romo, A; Juguilon, H; Weitzman, M D; Evans, R M; Maul, G G

    1996-01-15

    Wild-type PML and at least four other novel proteins are localized within discrete nuclear structures known as PODs. We demonstrate here that during adenovirus infection, immediate early viral proteins from the E1 and E4 transcription units associate with the POD, which in turn undergoes a dramatic morphological change. During this process, the auto-antigen Sp-100 and NDP55 but not PML, relocate from the POD to the viral inclusion bodies, the sites of adenovirus DNA replication and late RNA transcription. The E4-ORF3 11-kD protein alone will induce this reorganization and reciprocally, viruses carrying mutations in the E4-domain fail to do so. These same viral mutants are defective in viral replication as well as the accumulation of late viral mRNAs and host cell transcription shutoff. We show that interferon (INF) treatment enhances the expression of PML, reduces or blocks PODs reorganization, and inhibits BrdU incorporation into viral inclusion bodies. In addition, cell lines engineered to overexpress PML prevent PODs from viral-induced reorganization and block or severely delay adenovirus replication. These results suggest that viral replication relies on components of the POD and that the structure is a target of early viral proteins.

  13. PREFACE: 10th International Conference on Clustering Aspects of Nuclear Structure and Dynamics (CLUSTER'12)

    Science.gov (United States)

    Lovas, R. G.; Dombrádi, Zs; Kiss, G. G.; Kruppa, A. T.; Lévai, G.

    2013-04-01

    As Editors of this Proceedings volume and organizers as well as participants of the Conference, let us sum up a few facts about the Conference and let us add some subjective notes. The conference was held at Köolcsey Centre, a prestigious site of scientific and business meetings and cultural events in the city of Debrecen, Hungary, 24-28 September 2012. The city was chosen as the home of the Institute of Nuclear Research of the Hungarian Academy of Sciences, the home institution of the organizers. The Institute was visited by some of the participants. The organizing team was complemented by some belonging to the University of Debrecen, which made it possible to hold the conference dinner in the marvellous covered 'ceremonial court' of the University. The participants were taken for an excursion and wine tasting to a wine cellar at Tokaj, centre of, historically, the most significant wine producing area in Hungary. By coincidence, the closing day coincided with the day of what is called the Researchers' Night in the European Union. That night, (or rather, that evening) every year there is a public lecture in the Institute of Nuclear Research for a general audience, mainly secondary-school pupils. The public lecture scheduled on this occasion was held by one of the participants of the conference who represented the world outside Hungary and yet was able to deliver a talk in Hungarian. He is Professor Kálmán Varga, Vanderbilt University. The title of his talk was Simulation of Nanosystems ( http://kutatokejszakaja.hu/2012/esemenynaptar/esemeny.php?id=112&menu_id=4). There were 115 registered participants, representing 22 countries of Europe, Africa, Asia, Central, South and North America. We had 44 plenary talks and 47 talks presented in parallel sessions. In the Programme list the talks are arranged following the session structure of the Conference. In this list the invited speakers are marked by asterisks. All the talks in the plenary sessions were invited talks

  14. Nuclear envelope lamin-A couples actin dynamics with immunological synapse architecture and T cell activation.

    Science.gov (United States)

    González-Granado, José M; Silvestre-Roig, Carlos; Rocha-Perugini, Vera; Trigueros-Motos, Laia; Cibrián, Danay; Morlino, Giulia; Blanco-Berrocal, Marta; Osorio, Fernando G; Freije, José M P; López-Otín, Carlos; Sánchez-Madrid, Francisco; Andrés, Vicente

    2014-04-22

    In many cell types, nuclear A-type lamins regulate multiple cellular functions, including higher-order genome organization, DNA replication and repair, gene transcription, and signal transduction; however, their role in specialized immune cells remains largely unexplored. We showed that the abundance of A-type lamins was almost negligible in resting naïve T lymphocytes, but was increased upon activation of the T cell receptor (TCR). The increase in lamin-A was an early event that accelerated formation of the immunological synapse between T cells and antigen-presenting cells. Polymerization of F-actin in T cells is a critical step for immunological synapse formation, and lamin-A interacted with the linker of nucleoskeleton and cytoskeleton (LINC) complex to promote F-actin polymerization. We also showed that lamin-A expression accelerated TCR clustering and led to enhanced downstream signaling, including extracellular signal-regulated kinase 1/2 (ERK1/2) signaling, as well as increased target gene expression. Pharmacological inhibition of the ERK pathway reduced lamin-A-dependent T cell activation. Moreover, mice lacking lamin-A in immune cells exhibited impaired T cell responses in vivo. These findings underscore the importance of A-type lamins for TCR activation and identify lamin-A as a previously unappreciated regulator of the immune response.

  15. Nuclear weapons modernizations

    Energy Technology Data Exchange (ETDEWEB)

    Kristensen, Hans M. [Federation of American Scientists, Washington, DC (United States)

    2014-05-09

    This article reviews the nuclear weapons modernization programs underway in the world's nine nuclear weapons states. It concludes that despite significant reductions in overall weapons inventories since the end of the Cold War, the pace of reductions is slowing - four of the nuclear weapons states are even increasing their arsenals, and all the nuclear weapons states are busy modernizing their remaining arsenals in what appears to be a dynamic and counterproductive nuclear competition. The author questions whether perpetual modernization combined with no specific plan for the elimination of nuclear weapons is consistent with the nuclear Non-Proliferation Treaty and concludes that new limits on nuclear modernizations are needed.

  16. Chiral Unitary Dynamics of Hadrons and Hadrons in a Nuclear Medium

    CERN Document Server

    Oset, E; Gamermann, D; Vacas, M J Vicente; Strottman, D; Khemchandani, K P; Torres, A Martinez; Oller, J A; Roca, L; Napsuciale, Mauro

    2008-01-01

    In this talk I summarize recent findings around the description of axial vector mesons as dynamically generated states from the interaction of pseudoscalar mesons and vector mesons, dedicating some attention to the two $K_1(1270)$ states. Then I review the generation of open and hidden charm scalar and axial states, and how some recent experiment supports the existence of the new hidden charm scalar state predicted. I present recent results showing that the low lying $1/2^+$ baryon resonances for S=-1 can be obtained as bound states or resonances of two mesons and one baryon in coupled channels. Then show the differences with the S=0 case, where the $N^*(1710)$ appears also dynamically generated from the two pion one nucleon system, but the $N^*(1440)$ does not appear, indicating a more complex structure of the Roper resonance. Finally I shall show how the state X(2175), recently discovered at BABAR and BES, appears naturally as a resonance of the $\\phi K \\bar{K}$ system.

  17. Gas dynamics in the Milky Way: the nuclear bar and the 3-kpc arms

    CERN Document Server

    Rodríguez-Fernández, N J

    2009-01-01

    We discuss the results of the first model of the gas dynamics in the Milky Way in the presence of two bars: the large scale primary bar or boxy bulge and a secondary bar in the Galactic center region. We have obtained an accurate potential by modeling 2MASS star counts and we have used this potential to simulate the gas dynamics. As a first approximation we have used one single pattern speed \\Omega_p. The models with Omega_p=30-40 \\kmskpc and a primary bar orientation of 20-35 deg reproduce successfully many characteristics of the observed longitude-velocity diagrams as the terminal velocity curve or the spiral arm tangent points. The Galactic Molecular Ring is not an actual ring but the inner part of the spiral arms, within corotation. The model reproduces quantitatively the "3-kpc arm" and the recently found far-side counterpart, which are the lateral arms that contour the bar. In the Galactic center region, the model reproduces the 1-kpc HI ring and the Central Molecular Zone (CMZ), which is the gas respon...

  18. In silico simulation of inhibitor drug effects on nuclear factor-kappaB pathway dynamics.

    Science.gov (United States)

    Sung, Myong-Hee; Simon, Richard

    2004-07-01

    NF-kappaB is a transcription factor family that activates numerous genes that are related to cell survival, apoptosis, and cell migration. Its persistent activity is associated with tumor formation, growth, metastasis, and drug resistance in many cancer types, including lymphoma, colon cancer, and breast cancer. Current therapeutic efforts for inhibiting this central "switch" include using small molecules to block a selected target in this pathway. Recognizing the regulatory network structure of the NF-kappaB pathway, we examine in silico the effects of inhibitors targeting various network components, using a kinetic model of the pathway. By simulating the corresponding perturbed system dynamics, we show the resulting time course of inhibition has distinct target-specific profiles. In particular, greater oscillatory potential exists for inhibition of upstream events than for direct inhibition of NF-kappaB, at low drug concentrations. This phenomenon is observed also when we examine the dynamic effects of the recently approved proteasome inhibitor, bortezomib (PS-341), and compare it with other inhibitors, taking its pharmacokinetics into consideration. Such kinetic analyses of the "drugged" molecular system will facilitate optimal drug target selection and the development of treatment protocols for a molecularly targeted therapy.

  19. Triangle Universities Nuclear Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    This report contains brief papers that discusses the following topics: Fundamental Symmetries in the Nucleus; Internucleon Interactions; Dynamics of Very Light Nuclei; Facets of the Nuclear Many-Body Problem; and Nuclear Instruments and Methods.

  20. Dynamic behavior study of pilot flotation columns using nuclear techniques; Estudo do comportamento dinamico de colunas de flotacao utilizando tecnicas nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Adriano Ribeiro

    2005-07-01

    The dynamic behavior of a pilot flotation column has been studied using the tracer technique. Radioactive tracers emitting gamma radiation have been used for this purpose. Since this is a three phase system (air, water, and solid particles), having one entrance port and two exit flows, the residence time distribution (RTD) has been determined for both the liquid and solid phases. Moreover, the solids RTD has also been separately measured for four distinct size fractions, i.e. four determinations in all. Instantaneous pulse injections were performed in the feed flow and detected b scintillation probes with sodium iodide crystals doped with thallium, NaI(Tl), adequately collimated and placed at the tails and concentrate exit sections. The detector signals were duly counted, processed and stored by a computer. This setup allowed the RTD identification at the concentration and washing sections of the column to be directly obtained from the detector responses, without any interference whatsoever with the column operation regime. All the plant operational parameters were duly logged. An injection device was designed to introduce the tracer as close as possible to the column entrance and as instantaneously as feasible, thus simulating a Dirac delta impulse. A probe placed immediately downstream the injection position has been used to check its performance. The Peclet number (P{sub e}) and the average residence time (t-bar) were the system parameters determined by fitting the axial dispersion model to the experimental data. The model boundary conditions tested corresponded to the closed-closed and open-closed B.C.'s simulating the entrance-exit boundaries. It was demonstrated that recovery decreases with increasing the collect zone degree of mixing. By labeling both phases, the influence of the particle size distribution on the hydrodynamic behavior of the solids, as well as on the divergent behavior of the solid and liquid phases, has also checked. The closed

  1. Parallel input parallel output high voltage bi-directional converters for driving dielectric electro active polymer actuators

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.;

    2014-01-01

    is to design and implement driving circuits for the DEAP actuators for their use in various applications. This paper presents implementation of parallel input, parallel output, high voltage (~2.5 kV) bi-directional DC-DC converters for driving the DEAP actuators. The topology is a bidirectional flyback DC......-DC converter incorporating commercially available high voltage MOSFETs (4 kV) and high voltage diodes (5 kV). Although the average current of the aforementioned devices is limited to 300 mA and 150 mA, respectively, connecting the outputs of multiple converters in parallel can provide a scalable design....... This enables operating the DEAP actuators in various static and dynamic applications e.g. positioning, vibration generation or damping, and pumps. The proposed idea is experimentally verified by connecting three high voltage converters in parallel to operate a single DEAP actuator. The experimental results...

  2. Quantum ring-polymer contraction method: Including nuclear quantum effects at no additional computational cost in comparison to ab initio molecular dynamics

    Science.gov (United States)

    John, Christopher; Spura, Thomas; Habershon, Scott; Kühne, Thomas D.

    2016-04-01

    We present a simple and accurate computational method which facilitates ab initio path-integral molecular dynamics simulations, where the quantum-mechanical nature of the nuclei is explicitly taken into account, at essentially no additional computational cost in comparison to the corresponding calculation using classical nuclei. The predictive power of the proposed quantum ring-polymer contraction method is demonstrated by computing various static and dynamic properties of liquid water at ambient conditions using density functional theory. This development will enable routine inclusion of nuclear quantum effects in ab initio molecular dynamics simulations of condensed-phase systems.

  3. Quantum Ring-Polymer Contraction Method: Including nuclear quantum effects at no additional computational cost in comparison to ab-initio molecular dynamics

    CERN Document Server

    John, Chris; Habershon, Scott; Kühne, Thomas D

    2015-01-01

    We present a simple and accurate computational method, which facilitates ab-initio path-integral molecular dynamics simulations, where the quantum mechanical nature of the nuclei is explicitly taken into account, at essentially no additional computational cost in comparison to the corresponding calculation using classical nuclei. The predictive power of the proposed quantum ring-polymer contraction method is demonstrated by computing various static and dynamic properties of liquid water at ambient conditions. This development permits to routinely include nuclear quantum effects in ab-initio molecular dynamics simulations.

  4. Non-Abellian field dynamics in the early stage of ultrarelativistic nuclear collisions

    Energy Technology Data Exchange (ETDEWEB)

    Rischke, D.H. [Brookhaven National Lab., Upton, NY (United States)

    1997-09-22

    It was argued that the gluon field of a large, ultrarelativistic nucleus can be considered as a classical field for small values of the longitudinal momentum fraction x and on transverse momentum scales {Lambda}{sup 2}{sub QCD} << k{sup 2}{perpendicular} << {mu}{sup 2}, where {mu}{sup 2} is the transverse area density of color charges. The authors estimated {mu} {approx} 0.4 GeV for collisions of Au-nuclei at RHIC energies. Based on this argument, the gluon field produced in a collision of two ultrarelativistic nuclei is computed perturbatively by solving the classical Yang-Mills equations order by order in the strong coupling constant g. It is shown that to first order in g, the spectrum of produced gluons is identical to that obtained in a perturbative quantum calculation of gluon Bremsstrahlung. It is also identical with that of a coherent quantum state generated by independent collisions between the (classical) color charges in the two nuclei. The perturbative solution is unstable under perturbations. The instabilities arise from the non-Abelian terms in the equations of motion for the gluon field, which enter only at higher order in the perturbative solution scheme. The decay rate of the perturbative solution is shown to be of order {mu}. Since the non-Abelian terms describe the self-interaction of the produced gluon field, and since such interactions lead to thermalization, the decay rate provides an estimate for the thermalization time scale of classical color fields in ultrarelativistic nuclear collisions. For Au-nuclei, this time scale is therefore of order 0.5 fm/c, in agreement with results for the kinetic thermalization time scale.

  5. Conformational selection and functional dynamics of calmodulin: a (19)F nuclear magnetic resonance study.

    Science.gov (United States)

    Hoang, Joshua; Prosser, R Scott

    2014-09-16

    Calcium-bound calmodulin (CaM-4Ca(2+)) is innately promiscuous with regard to its protein interaction network within the cell. A key facet of the interaction process involves conformational selection. In the absence of a binding peptide, CaM-4Ca(2+) adopts an equilibrium between a native state (N) and a weakly populated near-native peptide-bound-like state (I), whose lifetime is on the order of 1.5 ms at 37 °C, based on (19)F nuclear magnetic resonance (NMR) Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion measurements. This peptide-bound-like state of CaM-4Ca(2+) is entropically stabilized (ΔS = 280 ± 35 J mol(-1) K(-1)) relative to the native state, water-depleted, and likely parental to specific bound states. Solvent depletion, conformational selection, and flexibility of the peptide-bound-like state may be important in priming the protein for binding. At higher temperatures, the exchange rate, kex, appears to markedly slow, suggesting the onset of misfolded or off-pathway states, which retards interconversion between N and I. (19)F NMR CPMG relaxation dispersion experiments with both CaM-4Ca(2+) and the separate N-terminal and C-terminal domains reveal the cooperative role of the two domains in the binding process and the flexibility of the N-terminal domain in facilitating binding. Thus, when calcium binds, calmodulin establishes its interaction with a multitude of protein binding partners, through a combination of conformational selection to a state that is parental to the peptide-bound state and, finally, induced fit.

  6. Molecular Dynamics Simulations of Aqueous and Confined Systems Relevant to the Supercritical Water Cooled Nuclear Reactor

    Science.gov (United States)

    Kallikragas, Dimitrios Theofanis

    Supercritical water (SCW) is the intended heat transfer fluid and potential neutron moderator in the proposed GEN-IV Supercritical Water Cooled Reactor (SCWR). The oxidative environment poses challenges in choosing appropriate design materials, and the behaviour of SCW within crevices of the passivation layer is needed for developing a corrosion control strategy to minimize corrosion. Molecular Dynamics simulations have been employed to obtain diffusion coefficients, coordination number and surface density characteristics, of water and chloride in nanometer-spaced iron hydroxide surfaces. Diffusion models for hydrazine are evaluated along with hydration data. Results demonstrate that water is more likely to accumulate on the surface at low density conditions. The effect of confinement on the water structure diminishes as the gap size increases. The diffusion coefficient of chloride decreases with larger surface spacing. Clustering of water at the surface implies that the SCWR will be most susceptible to pitting corrosion and stress corrosion cracking.

  7. Quasi-elastic reactions: an interplay of reaction dynamics and nuclear structure

    Energy Technology Data Exchange (ETDEWEB)

    Szilner, S; Jelavic-Malenica, D; Mijatovic, T; Soic, N [Ruder Botkovic Institute and University of Zagreb, Zagreb (Croatia); Corradi, L; Fioretto, E; Gadea, A; Mengoni, D; Stefanini, A M; Valiente-Dobon, J J [INFN - Laboratori Nazionali di Legnaro, Legnaro (Italy); Pollarolo, G [INFN and Universita di Torino (Italy); Beghini, S; Farnea, E; Lunardi, S; Montagnoli, G; Scarlassara, F; Ur, C A [INFN and Universita di Padova, Padova (Italy); Courtin, S; Haas, F; Lebhertz, D, E-mail: szilner@irb.hr [IPHC, CNRS/IN2P3 and Universite de Strasbourg, Strasbourg (France)

    2011-02-01

    The revival of transfer reaction studies benefited from the construction of the new generation large solid angle spectrometers based on trajectory reconstruction that reached an unprecedented efficiency and selectivity. The coupling of these spectrometers with large {gamma} arrays allowed the identification of individual excited states, their population pattern and decay modes via particle-{gamma} coincidences. In the present paper aspects of fragment-{gamma} coincidence studies measured with the Prisma-Clara set up in {sup 40}Ca+{sup 96}Zr and {sup 40}Ar+{sup 208}Pb are discussed. In particular, we report about states of particle-phonon character, supporting the idea that the relevant degrees of freedom acting in the reaction dynamics define the final yield distributions.

  8. Recent Advances in Bidirectional Modeling and Structural Control

    Directory of Open Access Journals (Sweden)

    Satyam Paul

    2016-01-01

    estimation of velocity and position from acceleration signals, and optimal placement of the sensors and control devices. The importance of control devices and its applications to minimize bidirectional vibrations has been illustrated. Finally, the applications of structural control systems in real buildings and their performance have been reviewed.

  9. Bi-directional Secure Communication Based on Discrete Chaotic Synchronization

    Institute of Scientific and Technical Information of China (English)

    LONG Min; QIU Shui-Sheng; PENG Fei

    2007-01-01

    Discrete chaotic systems are used for bi-directional secure communication. Both sides of communication keep sending signals to achieve their synchronization, and then recover the messages. However, the third side without keys cannot get useful information. Known-plaintext attack is also engaged to analyze this method, and the simulation results show that the proposed method can reach high security performance.

  10. Corticosterone alters AMPAR mobility and facilitates bidirectional synaptic plasticity

    NARCIS (Netherlands)

    Martin, S.; Henley, J.M.; Holman, D.; Zhou, M.; Wiegert, O.; van Spronsen, M.; Joëls, M.; Hoogenraad, C.C.; Krugers, H.J.

    2009-01-01

    Background: The stress hormone corticosterone has the ability both to enhance and suppress synaptic plasticity and learning and memory processes. However, until today there is very little known about the molecular mechanism that underlies the bidirectional effects of stress and corticosteroid hormon

  11. Corticosterone alters AMPAR mobility and facilitates bidirectional synaptic plasticity

    NARCIS (Netherlands)

    S. Martin (Stéphane); J.M. Henley (Jeremy); D. Holman (David); M. Zhou (Ming); O. Wiegert (Olof); M. van Spronsena (Myrrhe); M. Joëls (Marian); C.C. Hoogenraad (Casper); H.J. Krugers (Harmen)

    2009-01-01

    textabstractBackground: The stress hormone corticosterone has the ability both to enhance and suppress synaptic plasticity and learning and memory processes. However, until today there is very little known about the molecular mechanism that underlies the bidirectional effects of stress and corticost

  12. A Current-Fed Isolated Bidirectional DC-DC Converter

    DEFF Research Database (Denmark)

    Sun, Xiaofeng; Wu, Xiaoying; Shen, Yanfeng;

    2017-01-01

    This paper proposes a current-fed isolated bidirectional DC-DC converter (CF-IBDC) which has the advantages of wide input voltage range, low input current ripple, low conduction losses, and soft switching over the full operating range. Compared with conventional CF-IBDCs, the voltage spikes of th...

  13. Transfer of Pragmatic Competences: A Bi-Directional Perspective

    Science.gov (United States)

    Su, I-Ru

    2010-01-01

    This study investigated the bi-directionality of language transfer (first language [L1] to second language [L2] and L2 to L1) at the pragmatic level with a focus on the speech act of request. The L2 participants were Chinese English as a foreign language (EFL) learners at the intermediate and advanced levels. Data were collected via discourse…

  14. "Figuring" Bidirectional Home and School Connections along the Biliteracy Continuum

    Science.gov (United States)

    Fránquiz, María E.; Leija, María G.; Garza, Irene

    2015-01-01

    This article centers on the significant practices identified by bilingual teachers who participated in Proyecto Bilingüe, a specialized master's degree program. The notion of bidirectional theory of bilingual pedagogy and the theoretical construct of the continua of biliteracy are utilized to illustrate how the teachers centered home and school…

  15. Optimization Control of Bidirectional Cascaded DC-AC Converter Systems

    DEFF Research Database (Denmark)

    Tian, Yanjun

    in different power flow directions, a bidirectional impedance control method is also proposed to unify and improve the system stability. Control system type number is also analyzed in this thesis, then a symmetric proportional control method for the two stage cascaded converter is proposed to reduce the dc...

  16. Parenting and children's externalizing behavior: Bidirectionality during toddlerhood

    NARCIS (Netherlands)

    Verhoeven, Marjolein; Junger, Marianne; Aken, van Chantal; Dekovic, Maja; Aken, van Marcel A.G.

    2010-01-01

    This study examined the bidirectional relationship between parenting and boys' externalizing behaviors in a four-wave longitudinal study of toddlers. Participants were 104 intact two-parent families with toddler sons. When their sons were 17, 23, 29, and 35 months of age, mothers and fathers reporte

  17. Bidirectional Associations among Sensitive Parenting, Language Development, and Social Competence

    Science.gov (United States)

    Barnett, Melissa A.; Gustafsson, Hanna; Deng, Min; Mills-Koonce, W. Roger; Cox, Martha

    2012-01-01

    Rapid changes in language skills and social competence, both of which are linked to sensitive parenting, characterize early childhood. The present study examines bidirectional associations among mothers' sensitive parenting and children's language skills and social competence from 24 to 36?months in a community sample of 174 families. In addition,…

  18. On the Generating Power of Regularly Controlled Bidirectional Grammars

    NARCIS (Netherlands)

    Asveld, Peter R.J.; Hogendorp, Jan Anne

    1989-01-01

    RCB-grammars or regularly controlled bidirectional grammars are context-free grammars of which the rules can be used in a productive and in a reductive fashion. In addition, the application of these rules is controlled by a regular language. Several modes of derivation can be distinguished for this

  19. On the generating power of regularly controlled bidirection grammars

    NARCIS (Netherlands)

    Asveld, P.R.J.; Hogendorp, J.A.

    1991-01-01

    RCB-grammars or regularly controlled bidirectional grammars are context-free grammars of which the rules can be used in a productive and in a reductive fashion. In addition, the application of these rules is controlled by a regular language. Several modes of derivation can be distinguished for this

  20. Representation of concept lattices by bidirectional associative memories.

    Science.gov (United States)

    Bĕlohlávek, R

    2000-10-01

    This article presents a concept interpretation of patterns for bidirectional associative memory (BAM) and a representation of hierarchical structures of concepts (concept lattices) by BAMs. The constructive representation theorem provides a storing rule for a training set that allows a concept interpretation. Examples demonstrating the theorems are presented.

  1. High Efficient Bidirectional Battery Converter for residential PV Systems

    DEFF Research Database (Denmark)

    Pham, Cam; Kerekes, Tamas; Teodorescu, Remus

    2012-01-01

    the power to balance it. High efficient bidirectional converter for the battery storage is required due high system cost and because the power is processed twice. A 1.5kW prototype is designed and built with CoolMOS and SiC diodes, >;95% efficiency has been obtained with 200 kHz hard switching....

  2. Nuclear energy consumption, oil prices, and economic growth: Evidence from highly industrialized countries

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chien-Chiang, E-mail: cclee@cm.nsysu.edu.tw; Chiu, Yi-Bin

    2011-03-15

    This study utilizes the Johansen cointegration technique, the Granger non-causality test of Toda and Yamamoto (1995), the generalized impulse response function, and the generalized forecast error variance decomposition to examine the dynamic interrelationship among nuclear energy consumption, real oil price, oil consumption, and real income in six highly industrialized countries for the period 1965-2008. Our empirical results indicate that the relationships between nuclear energy consumption and oil are as substitutes in the U.S. and Canada, while they are complementary in France, Japan, and the U.K. Second, the long-run income elasticity of nuclear energy is larger than one, indicating that nuclear energy is a luxury good. Third, the results of the Granger causality test find evidence of unidirectional causality running from real income to nuclear energy consumption in Japan. A bidirectional relationship appears in Canada, Germany and the U.K., while no causality exists in France and the U.S. We also find evidence of causality running from real oil price to nuclear energy consumption, except for the U.S., and causality running from oil consumption to nuclear energy consumption in Canada, Japan, and the U.K., suggesting that changes in price and consumption of oil influence nuclear energy consumption. Finally, the results observe transitory initial impacts of innovations in real income and oil consumption on nuclear energy consumption. In the long run the impact of real oil price is relatively larger compared with that of real income on nuclear energy consumption in Canada, Germany, Japan, and the U.S.

  3. Evaluation of dynamic renal function by nuclear medicine using Tc-99m DTPA

    Energy Technology Data Exchange (ETDEWEB)

    Ishibashi, M.

    1987-01-01

    Dynamic renal function was nucleomedically evaluated using Tc-99m DTPA, and its value was assessed in various renal diseases. In addition to RI angiography, sequential image and renogram curve which were traditionally used as routine studies, Renal First Blood Flow (RFBF) by aortic blood flow exactly at the entrance of the renal artery, GFR (DTPA-GFR) by renal uptake and mean transit time (MTT) of the tracer by deconvolution analysis were measured. RFBF was useful to evaluate the stricture at the confluence of the renal artery and renal circulation, particularly cortical circulation. DTPA-GFR enabled the simple and rapid measurement of Total-GFR and Split-GFR. MTT was considered to be valuable in diagnosing obstructive nephropathy. In particular, RFBF was useful for assessment of renovascular hypertension. The measurement of the above-mentioned parameters made it possible to evaluate renal function objectively and quantitatively in addition to imaging and semiquantitative studies obtained by traditional routine examination. The major advantage of this procedure includes its possible performance along with routine renal function tests without any special preparation.

  4. The Specific Bias in Dynamic Monte Carlo Simulations of Nuclear Reactor

    Science.gov (United States)

    Yamamoto, Toshihisa; Endo, Hiroshi; Ishizu, Tomoko; Tatewaki, Isao

    2014-06-01

    During the development of Monte-Carlo-based dynamic code system, we have encountered two major Monte-Carlo-specific problems. One is the break down due to "false super-criticality" which is caused by an accidentally large eigenvalue due to statistical error in spite of the fact that the reactor is actually not. The other problem, which is the main topic in this paper, is that the statistical error in power level using the reactivity calculated with Monte Carlo code is not symmetric about its mean but always positively biased. This signifies that the bias is accumulated as the calculation proceeds and consequently results in over-estimation of the final power level. It should be noted that the bias will not eliminated by refining time step as long as the variance is not zero. A preliminary investigation on this matter using the one-group-precursor point kinetic equations was made and it was concluded that the bias in power level is approximately proportional to the product of variance in Monte Carlo calculation and elapsed time. This conclusion was verified with some numerical experiments. This outcome is important in quantifying the required precision of the Monte-Carlo-based reactivity calculations.

  5. DMPD: Nuclear factor-kappaB: activation and regulation during toll-like receptorsignaling. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 17349209 Nuclear factor-kappaB: activation and regulation during toll-like receptor...signaling. Carmody RJ, Chen YH. Cell Mol Immunol. 2007 Feb;4(1):31-41. (.png) (.svg) (.html) (.csml) Show Nuclear... factor-kappaB: activation and regulation during toll-like receptorsignaling. PubmedID 17349209 Title Nuclear

  6. LONG-TERM DYNAMICS OF RADIONUCLIDE VERTICAL MIGRATION IN SOILS OF THE CHERNOBYL NUCLEAR POWER PLANT EXCLUSION ZONE

    Energy Technology Data Exchange (ETDEWEB)

    Farfan, E

    2009-11-19

    The radioactive fallout from the Chernobyl Nuclear Power Plant (ChNPP) accident consisted of fuel and condensation components. An important radioecological task associated with the late phase of the accident is to evaluate the dynamics of radionuclide mobility in soils. Identification of the variability (or invariability) in the radionuclide transfer parameters makes it possible to (1) accurately predict migration patterns and biological availability of radionuclides and (2) evaluate long-term exposure trends for the population who may reoccupy the remediated abandoned areas. In 1986-1987, a number of experimental plots were established within various tracts of the fallout plume to assist with the determination of the long-term dynamics of radionuclide vertical migration in the soils. The transfer parameters for {sup 137}Cs, {sup 90}Sr, and {sup 239,240}Pu in the soil profile, as well as their ecological half-time of the radionuclide residence (T{sub 1/2}{sup ecol}) values in the upper 5-cm thick soil layers of different grasslands were estimated at various times since the accident. Migration characteristics in the grassland soils tend to decrease as follows: {sup 90}Sr > {sup 137}Cs {ge} {sup 239,240}Pu. It was found that the {sup 137}Cs absolute T{sub 1/2}{sup ecol} values are 3-7 times higher than its radioactive decay half-life value. Therefore, changes in the exposure dose resulting from the soil deposited {sup 137}Cs now depend only on its radioactive decay. The {sup 90}Sr T{sub 1/2}{sup ecol} values for the 21st year after the fallout tend to decrease, indicating an intensification of its migration capabilities. This trend appears consistent with a pool of mobile {sup 90}Sr forms that grows over time due to destruction of the fuel particles.

  7. Regulation of nuclear envelope dynamics via APC/C is necessary for the progression of semi-open mitosis in Schizosaccharomyces japonicus.

    Science.gov (United States)

    Aoki, Keita; Shiwa, Yuh; Takada, Hiraku; Yoshikawa, Hirofumi; Niki, Hironori

    2013-09-01

    Three types of mitosis, which are open, closed or semi-open mitosis, function in eukaryotic cells, respectively. The open mitosis involves breakage of the nuclear envelope before nuclear division, whereas the closed mitosis proceeds with an intact nuclear envelope. To understand the mechanism and significance of three types of mitotic division in eukaryotes, we investigated the process of semi-open mitosis, in which the nuclear envelope is only partially broken, in the fission yeast Schizosaccharomyces japonicus. In anaphase-promoting complex/cyclosome (APC/C) mutants of Sz. japonicus, the nuclear envelope remained relatively intact during anaphase, resulting in impaired semi-open mitosis. As a suppressor of apc2 mutant, a mutation of Oar2, which was a 3-oxoacyl-[acyl carrier protein] reductase, was obtained. The level of the Oar2, which had two destruction-box motifs recognized by APC/C, was increased in APC/C mutants. Furthermore, the defective semi-open mitosis observed in an apc2 mutant was restored by mutated oar2+. Based on these findings, we propose that APC/C regulates the dynamics of the nuclear envelope through degradation of Oar2 dependent on APC/C during the metaphase-to-anaphase transition of semi-open mitosis in Sz. japonicus.

  8. Thermodynamic properties and shear viscosity over entropy density ratio of nuclear fireball in a quantum-molecular dynamics model

    CERN Document Server

    Zhou, C L; Fang, D Q; Zhang, G Q

    2013-01-01

    Thermodynamic and transport properties of nuclear fireball created in the central region of heavy-ion collisions below 200 MeV/nucleon are investigated within the isospin-dependent quantum molecular dynamic (IQMD) model. These properties include time evolutions of the density, temperature, chemical potential, entropy density ($s$) and shear viscosity ($\\eta$) as well as density and temperature dependencies of the ratio of shear viscosity over entropy density ($\\eta/s$) etc. Based on the shear viscosity parametrization developed by Danilewicz and entropy density which is obtained by a generalized hot Thomas Fermi formalism, the ratio of shear viscosity over entropy density is calculated in the whole collision process as well as in the freeze-out stage. With the collision goes on, a transient minimal $\\eta/s$ with the value around 5/$4\\pi$ occurs in the largest compression stage. While, the relationship of $\\eta/s$ to tempertaure ($T$) in the freeze-out stage displays a local minimum which is about 9-10 times $...

  9. Exchange interaction-driven dynamic nuclear polarization in Mn-doped InGaAs/GaAs quantum dots

    Science.gov (United States)

    Krebs, O.; Baudin, E.; Lemaître, A.

    2016-11-01

    We investigated optical spin orientation and dynamic nuclear polarization (DNP) in individual self-assembled InGaAs/GaAs quantum dots (QDs) doped by a single Mn atom, a magnetic impurity providing a neutral acceptor A0 with an effective spin J =1 . We find that the spin of an electron photocreated in such a quantum dot can be efficiently oriented by a quasiresonant circularly polarized excitation. For the electron spin levels which are made quasidegenerate by a magnetic field compensating the exchange interaction Δe with A0, there is however a full depolarization due the anisotropic part of the exchange. Still, in most studied QDs, the spin polarized photoelectrons give rise to a pronounced DNP which grows with a longitudinal magnetic field until a critical field where it abruptly vanishes. For some QDs, several replica of such DNP sequence are observed at different magnetic fields. This striking behavior is qualitatively discussed as a consequence of different exchange interactions experienced by the electron, driving the DNP rate via the energy cost of electron-nucleus spin flip-flops.

  10. Structural and dynamic properties of amorphous solid dispersions: the role of solid-state nuclear magnetic resonance spectroscopy and relaxometry.

    Science.gov (United States)

    Paudel, Amrit; Geppi, Marco; Van den Mooter, Guy

    2014-09-01

    Amorphous solid dispersions (ASDs) are one of the frontier strategies to improve solubility and dissolution rate of poorly soluble drugs and hence tackling the growing challenges in oral bioavailability. Pharmaceutical performance, physicochemical stability, and downstream processability of ASD largely rely on the physical structure of the product. This necessitates in-depth characterization of ASD microstructure. Solid-state nuclear magnetic resonance (SS-NMR) techniques bear the ultimate analytical capabilities to provide the molecular level information on the dynamics and phase compositions of amorphous dispersions. SS-NMR spectroscopy/relaxometry, as a single and nondestructive technique, can reveal diverse and critical structural information of complex ASD formulations that are barely amenable from any other existing technique. The purpose of the current article is to review the recent most important studies on various sophisticated and information-rich one-dimensional and two-dimensional SS-NMR spectroscopy/relaxometry for the analysis of molecular mobility, miscibility, drug-carrier interactions, crystallinity, and crystallization in ASD. Some specific examples on microstructural elucidations of challenging ASD using multidimensional and multinuclear SS-NMR are presented. Additionally, some relevant examples on the utility of solution-NMR and NMR-imaging techniques for the investigation of the dissolution behavior of ASD are gathered.

  11. Nuclear Quantum Effects in Liquid Water: A Highly Accurate ab initio Path-Integral Molecular Dynamics Study

    Science.gov (United States)

    Distasio, Robert A., Jr.; Santra, Biswajit; Ko, Hsin-Yu; Car, Roberto

    2014-03-01

    In this work, we report highly accurate ab initio path-integral molecular dynamics (AI-PIMD) simulations on liquid water at ambient conditions utilizing the recently developed PBE0+vdW(SC) exchange-correlation functional, which accounts for exact exchange and a self-consistent pairwise treatment of van der Waals (vdW) or dispersion interactions, combined with nuclear quantum effects (via the colored-noise generalized Langevin equation). The importance of each of these effects in the theoretical prediction of the structure of liquid water will be demonstrated by a detailed comparative analysis of the predicted and experimental oxygen-oxygen (O-O), oxygen-hydrogen (O-H), and hydrogen-hydrogen (H-H) radial distribution functions as well as other structural properties. In addition, we will discuss the theoretically obtained proton momentum distribution, computed using the recently developed Feynman path formulation, in light of the experimental deep inelastic neutron scattering (DINS) measurements. DOE: DE-SC0008626, DOE: DE-SC0005180.

  12. Clustering dynamics in water/methanol mixtures: a nuclear magnetic resonance study at 205 k

    Science.gov (United States)

    Corsaro, Carmelo; Spooren, Jeroen; Branca, Caterina; Leone, Nancy; Broccio, Matteo; Kim, Chansoo; Chen, Sow-Hsin; Stanley, H Eugene; Mallamace, Francesco

    2008-08-28

    Proton nuclear magnetic resonance (1H NMR) experiments have been performed to measure the spin-lattice, T1, and spin-spin, T2, relaxation times of the three functional groups in water/methanol mixtures at different methanol molar fractions (XMeOH=0, 0.04, 0.1, 0.24, 0.5, 1) as a function of temperature in the range 205 Kdynamics that determines their thermodynamic properties. In particular, we observe how the interplay between hydrophobicity and hydrophilicity changes with temperature and influences the peculiar thermal behavior of the NMR relaxation times of the solution. The obtained results are interpreted in terms of the existence of stable water-methanol clusters at high temperature whereas, upon cooling to low temperature, clusters of single species are present in the mixture.

  13. Phase transitions and anionic dynamics of dimethylammonium hexachlorotellurate(IV) as studied by pulsed nuclear quadrupole resonance of chlorine

    Science.gov (United States)

    Ishikawa, Atsushi; Horiuchi, Keizo; Ikeda, Ryuichi; Nakamura, Daiyu

    1989-01-01

    The temperature dependence of 35Cl NQR frequencies has been reinvestigated for dimethylammonium hexachlorotellurate(IV) using an FT NQR spectrometer. A new line is observed just above the lowest-frequency line already reported for the intermediate-temperature phase. In the lowest-temperature phase, the temperature dependence is definitely determined by finding new lines. The NQR frequencies can be precisely measured even in the vicinity of the phase transitions. The temperature dependence of the nuclear quadrupole relaxation time, T1Q of 35Cl and 37Cl nuclei has also been observed. In a temperature range 64-160 K, the isotope ratio, T1Q( 37Cl)/ T1Q( 35Cl) is 1.5 for each line, suggesting that the quadrupolar relaxation arises mainly from the libration of the complex anion. Above 160 K, T1Q decreases very rapidly with increasing temperature for each line. This can be interpreted in terms of the onset of the reorientation of the anion as a whole, which is responsible for the fade-out phenomenon of the two lines occurring near 220 K. The nature of the phase transitions and the anionic dynamics are discussed in detail. Especially, the phase transition at 96 K which is rather unusual and is explained through softening of the librations and the rotational displacement of the anions successively operated.

  14. Dynamics of asymmetric non-polymeric binary glass formers—A nuclear magnetic resonance and dielectric spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Pötzschner, B.; Mohamed, F.; Lichtinger, A.; Bock, D.; Rössler, E. A., E-mail: ernst.roessler@uni-bayreuth.de [Experimentalphysik II, Universität Bayreuth, 95440 Bayreuth (Germany)

    2015-10-21

    We study a dynamically asymmetric binary glass former with the low-T{sub g} component m-tri-cresyl phosphate (m-TCP: T{sub g} = 206 K) and a spirobichroman derivative as a non-polymeric high-T{sub g} component (T{sub g} = 382 K) by means of {sup 1}H nuclear magnetic resonance (NMR), {sup 31}P NMR, and dielectric spectroscopy which allow component-selectively probing the dynamics. The entire concentration range is covered, and two main relaxation processes with two T{sub g} are identified, T{sub g1} and T{sub g2}. The slower one is attributed to the high-T{sub g} component (α{sub 1}-process), and the faster one is related to the m-TCP molecules (α{sub 2}-process). Yet, there are indications that a small fraction of m-TCP is associated also with the α{sub 1}-process. While the α{sub 1}-relaxation only weakly broadens upon adding m-TCP, the α{sub 2}-relaxation becomes extremely stretched leading to quasi-logarithmic correlation functions at low m-TCP concentrations—as probed by {sup 31}P NMR stimulated echo experiments. Frequency-temperature superposition does not apply for the α{sub 2}-process and it reflects an isotropic, liquid-like motion which is observed even below T{sub g1}, i.e., in the matrix of the arrested high-T{sub g} molecules. As proven by 2D {sup 31}P NMR, the corresponding dynamic heterogeneities are of transient nature, i.e., exchange occurs within the distribution G(lnτ{sub α2}). At T{sub g1} a crossover is found for the temperature dependence of (mean) τ{sub α2}(T) from non-Arrhenius above to Arrhenius below T{sub g1} which is attributed to intrinsic confinement effects. This “fragile-to-strong” transition also leads to a re-decrease of T{sub g2}(c{sub m−TCP}) at low concentration c{sub m−TCP}, i.e., a maximum is observed in T{sub g2}(c{sub m−TCP}) while T{sub g1}(c{sub m−TCP}) displays the well-known plasticizer effect. Although only non-polymeric components are involved, we re-discover essentially all features previously

  15. Investigations into the Structure and Dynamics of Chalcogenide Glasses using High-Resolution Nuclear Magnetic Resonance Spectroscopy

    Science.gov (United States)

    Kaseman, Derrick Charles

    Chalcogenide glasses constitute an important class of materials that are sulfides, selenides or tellurides of group IV and/or V elements, namely Ge, As, P and Si with minor concentrations of other elements such as Ga, Sb, In. Because of their infrared transparency that can be tuned by changing chemistry and can be actively altered by exposure to band gap irradiation, chalcogenide glasses find use in passive and active optical devices for applications in the areas of photonics, remote sensing and memory technology. Therefore, it is important to establish predictive models of structure-property relationships for these materials for optimization of their physical properties for various applications. Structural elucidation of chalcogenide glasses is experimentally challenging and in order to make predictive structural models, structural units at both short and intermediate -range length scales must be identified and quantified. Nuclear Magnetic Resonance (NMR) spectroscopy is an element-specific structural probe that is uniquely suited for this task, but resolution and sensitivity issues have severely limited the applications of such techniques in the past. The recent development of multi-dimensional solid-state NMR techniques, such as Phase Adjusted Spinning Sidebands (PASS) and Magic Angle Turning (MAT) can potentially alleviate such issues. In this study novel two-dimensional, high-resolution 77Se and 125Te MATPASS NMR spectroscopic techniques are utilized to elucidate quantitatively the compositional evolution of the short- and intermediate- range atomic structure in three binary chalcogenide glass-forming systems, namely: GexSe100-x, AsxSe100-x , and AsxTe100-x. The spectroscopic results provide unambiguous site speciation and quantification for short- and intermediate-range structural motifs present in these glasses. In turn, for all systems, robust structural models and the corresponding structure-property relationships are successfully established as a function

  16. Modelling the local atomic structure of molybdenum in nuclear waste glasses with ab initio molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2016-01-01

    The nature of chemical bonding of molybdenum in high level nuclear waste glasses has been elucidated by ab initio molecular dynamics simulations. Two compositions, (SiO2)57.5 – (B2O3)10 – (Na2O)15 – (CaO)15 – (MoO3)2.5 and (SiO2)57.3 – (B2O3)20 – (Na2O)6.8 – (Li2O)13.4 – (MoO3)2.5 , were considered in order to investigate the effect of ionic and covalent components on the glass structure and the formation of the crystallisation precursors (Na2MoO4 and CaMoO4). The coordination environments of Mo cations and the corresponding bond lengths calculated from our model are in excellent agreement with experimental observations. The analysis of the first coordination shell reveals two different types of molybdenum host matrix bonds in the lithium sodium borosilicate glass. Based on the structural data and the bond valence model, we demonstrate that the Mo cation can be found in a redox state and the molybdate tetrahedron can be connected with the borosilicate network in a way that inhibits the formation of crystalline molybdates. These results significantly extend our understanding of bonding in Mo-containing nuclear waste glasses and demonstrate that tailoring the glass composition to specific heavy metal constituents can facilitate incorporation of heavy metals at high concentrations. K.K. was supported through the Impact Studentship scheme at UCL co-funded by the IHI Corporation and UCL. P.V.S. thanks the Royal Society, which supported preliminary work on this project, and the Laboratory Directed Research and Development program at PNNL, a multiprogram national laboratory operated by Battelle for the U.S. Department of Energy. Via our membership of the UK's HEC Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202), this work used the ARCHER UK National Supercomputing Service (http://www.archer.ac.uk).

  17. A versatile and modular quasi optics-based 200 GHz dual dynamic nuclear polarization and electron paramagnetic resonance instrument

    Science.gov (United States)

    Siaw, Ting Ann; Leavesley, Alisa; Lund, Alicia; Kaminker, Ilia; Han, Songi

    2016-03-01

    Solid-state dynamic nuclear polarization (DNP) at higher magnetic fields (>3 T) and cryogenic temperatures (∼2-90 K) has gained enormous interest and seen major technological advances as an NMR signal enhancing technique. Still, the current state of the art DNP operation is not at a state at which sample and freezing conditions can be rationally chosen and the DNP performance predicted a priori, but relies on purely empirical approaches. An important step towards rational optimization of DNP conditions is to have access to DNP instrumental capabilities to diagnose DNP performance and elucidate DNP mechanisms. The desired diagnoses include the measurement of the "DNP power curve", i.e. the microwave (MW) power dependence of DNP enhancement, the "DNP spectrum", i.e. the MW frequency dependence of DNP enhancement, the electron paramagnetic resonance (EPR) spectrum, and the saturation and spectral diffusion properties of the EPR spectrum upon prolonged MW irradiation typical of continuous wave (CW) DNP, as well as various electron and nuclear spin relaxation parameters. Even basic measurements of these DNP parameters require versatile instrumentation at high magnetic fields not commercially available to date. In this article, we describe the detailed design of such a DNP instrument, powered by a solid-state MW source that is tunable between 193 and 201 GHz and outputs up to 140 mW of MW power. The quality and pathway of the transmitted and reflected MWs is controlled by a quasi-optics (QO) bridge and a corrugated waveguide, where the latter couples the MW from an open-space QO bridge to the sample located inside the superconducting magnet and vice versa. Crucially, the versatility of the solid-state MW source enables the automated acquisition of frequency swept DNP spectra, DNP power curves, the diagnosis of MW power and transmission, and frequency swept continuous wave (CW) and pulsed EPR experiments. The flexibility of the DNP instrument centered around the QO MW

  18. Density functional approaches to collective phenomena in nuclei: Time-dependent density-functional theory for perturbative and non-perturbative nuclear dynamics

    CERN Document Server

    Nakatsukasa, Takashi

    2012-01-01

    We present the basic concepts and our recent developments in the density functional approaches with the Skyrme functionals for describing nuclear dynamics at low energy. The time-dependent density-functional theory (TDDFT) is utilized for the exact linear response with an external perturbation. For description of collective dynamics beyond the perturbative regime, we present a theory of a decoupled collective submanifold to describe for a slow motion based on the TDDFT. Selected applications are shown to demonstrate the quality of their performance and feasibility. Advantages and disadvantages in the numerical aspects are also discussed.

  19. Dynamics of iodine anions in KI and LiI aqueous solutions studied by 127I nuclear resonant quasi-elastic scattering

    Science.gov (United States)

    Haruki, Rie; Koshimizu, Masanori; Nishikido, Fumihiko; Masuda, Ryo; Kobayashi, Yasuhiro; Seto, Makoto; Yoda, Yoshitaka; Kishimoto, Shunji

    2016-12-01

    The dynamics of iodine ions in potassium iodide (KI) and lithium iodide (LiI) aqueous solutions have been studied through 127I nuclear resonant quasi-elastic scattering (NRQES). A newly developed Si (12 2 2) double crystal monochromator for 127I 57.6 keV excitation is used. Broadening due to a diffusive motion is measured in the energy spectra of the NRQES from the solutions.

  20. Development and application of computational fluid dynamics approaches within the European project THINS for the simulation of next generation nuclear power systems

    Energy Technology Data Exchange (ETDEWEB)

    Papukchiev, Angel, E-mail: angel.papukchiev@grs.de [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) mbH, Garching n. Munich (Germany); Roelofs, Ferry; Shams, Afaque [Nuclear Research and Consultancy Group, Petten (Netherlands); Lecrivain, Gregory [Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Ambrosini, Walter [University of Pisa, Pisa (Italy)

    2015-08-15

    Highlights: • Thermal–hydraulic crosscutting issues related to Generation IV reactor concepts have been investigated within the European Project THINS. • New nuclear systems are characterized by various non-unity Prandtl number coolants. • Improvements in the turbulence modeling for innovative coolants have been achieved. • Extensive development and validation work has been done. - Abstract: Today computational fluid dynamics (CFD) is widely used in industrial companies, research institutes and technical safety organizations to supplement the design and analysis of diverse technical components and large systems. Such numerical programs are applied to better understand complex fluid flow and heat transfer phenomena. In the last decades there is an increasing interest in the nuclear community to utilize such advanced programs for the evaluation of different nuclear reactor safety issues, where traditional analysis tools show deficiencies. Within the FP7 European project THINS (Thermal Hydraulics of Innovative Nuclear Systems), CFD and coupled 1D-3D thermal–hydraulic simulations are being carried out. These are dedicated to the analysis of the thermal–hydraulics of gas, liquid metal and supercritical water cooled reactors. Such concepts utilize innovative fluids, which have different properties from the ones used in the current nuclear reactors. In order to improve the thermal–hydraulic predictions of their behavior, CFD development, application and validation activities are performed within THINS. This overview paper highlights some of the CFD related work within the European project.

  1. Heating performance investigation of a bidirectional partition fluid thermal diode

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Xiande; Xia, Lulu [Institute of Air Conditioning and Refrigeration, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing, Jiangsu Province 210016 (China)

    2010-03-15

    A novel thermal diode, bidirectional partition fluid thermal diode (BPFTD) that is fabricated by integrating a thermal insulation partition and a movable control blade into a water tank, is proposed. The bidirectional configuration allows the BPFTD to serve both passive solar heating in winter and passive cooling in summer. BPFTD heating performances are tested with two side-by-side hot boxes and compared experimentally with a water-wall having optimum thickness. Two stages of experiments are conducted. The first stage is to investigate an appropriate position of BPFTD partition, and the second compares the BPFTD with the water-wall. The test results show that the BPFTD has much better heating performances than the water-wall. Analysis indicates that the BPFTD may increase heat supply by around 140% when a single glazing cover without night insulation is used and by around 70% in case of using a double glazing cover without night insulation. (author)

  2. Bidirectionality From Cargo Thermal Fluctuations in Motor-Mediated Transport

    CERN Document Server

    Miles, Christopher E

    2016-01-01

    Molecular motor proteins serve as an essential component of intracellular transport by generating forces to haul cargoes along cytoskeletal filaments. In some circumstances, two species of motors that are directed oppositely (e.g. kinesin, dynein) can be attached to the same cargo. The resulting net motion is known to be bidirectional, but the mechanism of switching remains unclear. In this work, we propose a mean-field mathematical model of the mechanical interactions of two populations of molecular motors with diffusion of the cargo (thermal fluctuations) as the fundamental noise source. By studying a simplified model, the delayed response of motors to rapid fluctuations in the cargo is quantified, allowing for the reduction of the full model to two "characteristic positions" of each of the motor populations. The system is then found to be "metastable", switching between two distinct directional transport states, or bidirectional motion. The time to switch between these states is then investigated using WKB...

  3. High Voltage Bi-directional Flyback Converter for Capacitive Actuator

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    This paper presents a high voltage DC-DC converter topology for bi-directional energy transfer between a low voltage DC source and a high voltage capacitive load. The topology is a bi-directional flyback converter with variable switching frequency control during the charge mode, and constant...... switching frequency control during the discharge mode. The converter is capable of charging the capacitive load from 24 V DC source to 2.5 kV, and discharges it to 0 V. The flyback converter has been analyzed in detail during both charge and discharge modes, by considering all the parasitic elements...... in the converter, including the most dominating parameters of the high voltage transformer viz., self-capacitance and leakage inductance. The specific capacitive load for this converter is a dielectric electro active polymer (DEAP) actuator, which can be used as an effective replacement for conventional actuators...

  4. A mixing evolution model for bidirectional microblog user networks

    Science.gov (United States)

    Yuan, Wei-Guo; Liu, Yun

    2015-08-01

    Microblogs have been widely used as a new form of online social networking. Based on the user profile data collected from Sina Weibo, we find that the number of microblog user bidirectional friends approximately corresponds with the lognormal distribution. We then build two microblog user networks with real bidirectional relationships, both of which have not only small-world and scale-free but also some special properties, such as double power-law degree distribution, disassortative network, hierarchical and rich-club structure. Moreover, by detecting the community structures of the two real networks, we find both of their community scales follow an exponential distribution. Based on the empirical analysis, we present a novel evolution network model with mixed connection rules, including lognormal fitness preferential and random attachment, nearest neighbor interconnected in the same community, and global random associations in different communities. The simulation results show that our model is consistent with real network in many topology features.

  5. A Bidirectional Relationship between Conceptual Organization and Word Learning

    Directory of Open Access Journals (Sweden)

    Tanya Kaefer

    2013-01-01

    Full Text Available This study explores the relationship between word learning and conceptual organization for preschool-aged children. We proposed a bidirectional model in which increases in word learning lead to increases in taxonomic organization, which, in turn, leads to further increases in word learning. In order to examine this model, we recruited 104 4-year olds from Head Start classrooms; 52 children participated in a two-week training program, and 52 children were in a control group. Results indicated that children in the training program learned more words and were more likely to sort taxonomically than children in the control condition. Furthermore, the number of words learned over the training period predicted the extent to which children categorized taxonomically. Additionally, this ability to categorize taxonomically predicted the number of words learned outside the training program, over and above the number of words learned in the program. These results suggest a bi-directional relationship between conceptual organization and word learning.

  6. Bidirectional selection between two classes in complex social networks

    CERN Document Server

    Zhou, Bin; Jiang, Luo-Luo; Wang, Nian-Xin; Wang, Bing-Hong

    2015-01-01

    The bidirectional selection between two classes widely emerges in various social lives, such as commercial trading and mate choosing. Until now, the discussions on bidirectional selection in structured human society are quite limited. We demonstrated theoretically that the rate of successfully matching is affected greatly by individuals neighborhoods in social networks, regardless of the type of networks. Furthermore, it is found that the high average degree of networks contributes to increasing rates of successful matches. The matching performance in different types of networks has been quantitatively investigated, revealing that the small-world networks reinforces the matching rate more than scale-free networks at given average degree. In addition, our analysis is consistent with the modeling result, which provides the theoretical understanding of underlying mechanisms of matching in complex networks.

  7. Effects of bidirectional regulation on noises in gene networks.

    Science.gov (United States)

    Zheng, Xiudeng; Tao, Yi

    2010-03-14

    To investigate the effects of bidirectional regulation on the noise in protein concentration, a theoretical and simple three-gene network model is considered. The basic idea behind this model is from Paulsson's proposition (J. Paulsson, Phys. Life Rev. 2005, 2, 157-175), where the synthesis and degradation of a mRNA species corresponding to a target protein are regulated directly and indirectly by a certain sigma-factor, and a random increase in the concentration of the sigma-factor should increase both the synthesis and degradation rates of the mRNA species (bidirectional regulation). Using the standard Omega-expansion technique (linear noise approximation) and Monte Carlo simulation, our main results show clearly that for the steady-state statistics the effects of the noise of the sigma-factor on the stochastic fluctuation of the target protein could partially cancel out.

  8. Bi-directional associations between psychological arousal, cortisol, and sleep

    DEFF Research Database (Denmark)

    Garde, Anne Helene; Albertsen, Karen; Persson, Roger

    2012-01-01

    The aim was to elucidate the possible bi-directional relation between daytime psychological arousal, cortisol, and self-reported sleep in a group of healthy employees in active employment. Logbook ratings of sleep (Karolinska Sleep Questionnaire), stress, and energy, as well as positive and negat......The aim was to elucidate the possible bi-directional relation between daytime psychological arousal, cortisol, and self-reported sleep in a group of healthy employees in active employment. Logbook ratings of sleep (Karolinska Sleep Questionnaire), stress, and energy, as well as positive...... and problems during the day. The results underpin the possibility that arousal and poor sleep might create a self-reinforcing vicious circle that negatively affects a person's well-being....

  9. An Efficient DC- DC Converter with Bidirectional Power Flow

    Directory of Open Access Journals (Sweden)

    N.RAJARAJESWARI

    2008-07-01

    Full Text Available This paper introduces a Bi-directional DC-DC converter with adaptive fuzzy logic controller. Bidirectional power flow is obtained by same power components and provides a simple, efficient, and galvanically isolated converter. In the presence of DC mains the converter operates as buck converter and charges the battery. When the DC mains fails, the converter operates as boost converter and the down stream converter is fed by the battery. The power switches are controlled by Pulse Width Modulation technique and the pulses are generated by the application of fuzzy logic with an adoption algorithm. The proposed converter is simulated using MATLAB and laboratory prototype was developed to validate the simulation results.

  10. Bi-directional normalized difference vegetation index: concept and application

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The data products of land surface bi-directional reflectance distribution function (BRDF) from the space-borne Polarization and Directionality of the Earth Reflectance (POLDER) of France and the Moderate Resolution Imaging Spectroradiometer (MODIS)of USA are available recently, but the atmospheric correction for meeting the requirement of quantitative remote sensing is still a very dfficult problem. This paper presents a concept: bi-directional normalized difference vegetation index (Bi-NDVI), in order to consider simul taneously the effects of both land surface BRDF and atmospheric path scattering. An atmospheric quality index is thus defined for satellite multi-angular observations. The quality of MODIS/BRDF data products can be improved notably through iterative inversion weighed by this index.

  11. Fatigue testing of thermoformed bidirectional LDF™-composites

    Science.gov (United States)

    Schuster, J.; Friedrich, K.

    1994-01-01

    Specimens made of Long Discontinuous Fiber (LDF™) composite material were elongated to different states of deformation by thermoforming. Tension-tension-fatigue tests were performed using waisted bidirectional specimens cut out of the thermoformed parts. These resulted in similar shapes of the Wöhler-curves fairly independently of the deformation state of the LDF™-material. In addition, the static strength values were not very much influenced by the elongation of the specimens. The specimens were nondestructively inspected by ultrasonics and thermography.

  12. Bidirectional Microglia-Neuron Communication in the Healthy Brain

    OpenAIRE

    2013-01-01

    Unlike other resident neural cells that are of neuroectodermal origin, microglia are resident neural cells of mesodermal origin. Traditionally recognized for their immune functions during disease, new roles are being attributed to these cells in the development and maintenance of the central nervous system (CNS) including specific communication with neurons. In this review, we highlight some of the recent findings on the bidirectional interaction between neurons and microglia. We discuss thes...

  13. Isolated Boost Converter with Bidirectional Operation for Supercapacitor Applications

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Mira Albert, Maria del Carmen; Sen, Gökhan;

    2013-01-01

    This paper presents an isolated bidirectional dc/dc converter based on primary parallel isolated boost converter (PPIBC). This topology is an efficient solution in low voltage high power applications due to its ability to handle high currents in the low voltage side. In this paper, the converter ...... interconnecting two battery banks. A second prototype has been constructed and tested for supercapacitor operation in constant power charge mode....

  14. Design of general bidirectional associative memories with improved recall capability.

    Science.gov (United States)

    Lee, Donq-Liang; Chuang, Thomas C

    2004-10-01

    The concept of qth order Hamming ball for general bidirectional associative memories (GBAMs) is presented, which results in an enhanced recall capability. A technique based on the minimum overlap algorithm (MOA) is proposed to deal with the separability problem of the qth order Hamming balls. Simulation results show that the recall capability obtained by using the proposed method is indeed larger than that obtained by using the conventional method.

  15. Ocean dynamic processes causing spatially heterogeneous distribution of sedimentary caesium-137 massively released from the Fukushima Daiichi Nuclear Power Plant

    Science.gov (United States)

    Higashi, H.; Morino, Y.; Furuichi, N.; Ohara, T.

    2015-12-01

    Massive amounts of anthropogenic radiocaesium 137Cs that were released into the environment by the Fukushima Daiichi Nuclear Power Plant accident in March 2011 are widely known to have extensively migrated to Pacific Ocean sediment off of eastern Japan. Several recent reports have stated that the sedimentary 137Cs is now stable with a remarkably heterogeneous distribution. The present study elucidates ocean dynamic processes causing this heterogeneous sedimentary 137Cs distribution in and around the shelf off Fukushima and adjacent prefectures. We performed a numerical simulation of oceanic 137Cs behaviour for about 10 months after the accident, using a comprehensive dynamic model involving advection-diffusion transport in seawater, adsorption and desorption to and from particulate matter, sedimentation and suspension on and from the bottom, and vertical diffusion transport in the sediment. A notable simulated result was that the sedimentary 137Cs significantly accumulated in a swath just offshore of the shelf break (along the 50-100 m isobath) as in recent observations, although the seabed in the entire simulation domain was assumed to have ideal properties such as identical bulk density, uniform porosity, and aggregation of particles with a single grain diameter. This result indicated that the heterogeneous sedimentary 137Cs distribution was not necessarily a result of the spatial distribution of 137Cs sediment adsorptivity. The present simulation suggests that the shape of the swath is mainly associated with spatiotemporal variation between bottom shear stress in the shallow shelf (< 50 m depths) and that offshore of the shelf break. In a large part of the shallow shelf, the simulation indicated that strong bottom friction suspending particulate matter from the seabed frequently occurred via a periodic spring tide about every 2 weeks and via occasional strong wind. The sedimentary 137Cs thereby could hardly stay on the surface of the seabed with the result that

  16. Development of advanced risk informed asset management tool based on system dynamics approach for nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Gyoung Cheol

    2007-02-15

    In the competitive circumstance of electricity industry, the economic efficiency of electricity generation facility is the most important factor to increase their competitiveness. For nuclear power plant (NPP), safety is also an essential factor. Over fast several years, efforts for development of safety concerned and financial asset maximizing method, process and tools have been continued internationally and Risk-Informed Asset Management (RIAM) methodology is suggested by Electric Power Research Institute (EPRI). This RIAM methodology is expected to provide plant operators with a project prioritization and life cycle management planning tool for making long-term maintenance plans, guiding plant budgeting, and determining the sensitivity of a plant's economic risk to the reliability and availability of system, structure, and components (SSC), as well as other technical and economic parameters. The focus of this study is to develop model that help us to resource allocation, to find what effect such allocations on the plant economic and safety performance. Detailed research process for this goal is as follow; First step for development of advanced RIAM model is to review for current RIAM model of EPRI. This part describes the overall RIAM methodology including its conceptual model, implementation process, modular approach etc. Second step is to perform feasibility study for current EPRI's RIAM model with case study. This part shows the result of feasibility study for current RIAM method by case study and discussion for result. Finally, concept of Advanced RIAM model is developed based on system dynamics approach and parameter relationship is formulated. In advanced RIAM Model, Identification of scheduled maintenance effect on other parameters and the relationship between PM Activity and failure rate is most important factor. In this study, these relationships are formulated based on system dynamics approach. Creations of these modeling tool using Vensim

  17. Hybrid semiconductor-dielectric metamaterial modulation for switchable bi-directional THz absorbers

    Science.gov (United States)

    Le, Ly Nguyen; Thang, Nguyen Manh; Thuy, Le Minh; Tung, Nguyen Thanh

    2017-01-01

    There is an increasing interest for electromagnetic metamaterials that show mutable absorption properties with real-time and dynamic control. In this paper, we investigate a modulation of bi-directional metamaterial absorbers that is thermally switchable at terahertz frequencies. The metamaterial absorber is composed of symmetric hybrid semiconductor-dielectric cut-wire-pair structures, whose electromagnetic responses can be actively manipulated by utilizing an external heat source. As increasing the temperature of metamaterials from 300 to 350 K, we demonstrate that the magnetic resonance can be systematically blue-shifted and overlapped with the electric resonance, which is unaffectedly settled at about 0.8 THz. This superposition provides an effective mechanism to control the absorption intensity from 43% to nearly 95%. Finite integration simulation technique, standard retrieval method, and equivalent circuit model are employed to elaborate our idea.

  18. Definition of a Bidirectional Activity-Dependent Pathway Involving BDNF and Narp

    Directory of Open Access Journals (Sweden)

    Abigail Mariga

    2015-12-01

    Full Text Available One of the cardinal features of neural development and adult plasticity is the contribution of activity-dependent signaling pathways. However, the interrelationships between different activity-dependent genes are not well understood. The immediate early gene neuronal-activity-regulated pentraxin (NPTX2 or Narp encodes a protein that has been associated with excitatory synaptogenesis, AMPA receptor aggregation, and the onset of critical periods. Here, we show that Narp is a direct transcriptional target of brain-derived neurotrophic factor (BDNF, another highly regulated activity-dependent gene involved in synaptic plasticity. Unexpectedly, Narp is bidirectionally regulated by BDNF. Acute BDNF withdrawal results in downregulation of Narp, whereas transcription of Narp is greatly enhanced by BDNF. Furthermore, our results show that BDNF directly regulates Narp to mediate glutamatergic transmission and mossy fiber plasticity. Hence, Narp serves as a significant epistatic target of BDNF to regulate synaptic plasticity during periods of dynamic activity.

  19. Bi-directional interhemispheric inhibition during unimanual sustained contractions

    Directory of Open Access Journals (Sweden)

    Ni Zhen

    2009-04-01

    Full Text Available Abstract Background The interaction between homologous muscle representations in the right and left primary motor cortex was studied using a paired-pulse transcranial magnetic stimulation (TMS protocol known to evoke interhemispheric inhibition (IHI. The timecourse and magnitude of IHI was studied in fifteen healthy right-handed adults at several interstimulus intervals between the conditioning stimulus and test stimulus (6, 8, 10, 12, 30, 40, 50 ms. IHI was studied in the motor dominant to non-dominant direction and vice versa while the right or left hand was at rest, performing isometric contraction of the first dorsal interosseous (FDI muscle, and isometric contraction of the FDI muscle in the context of holding a pen. Results Compared with rest, IHI was reduced at all ISIs during contraction of either type (with or without the context of pen. IHI was reduced bi-directionally without evidence of hemispheric dominance. Further, contraction of the hand contralateral to the conditioning and test pulse yielded similar reductions in IHI. Conclusion These data provide evidence for bi-directional reduction of IHI during unimanual contractions. During unimanual, sustained contractions of the hand, the contralateral and ipsilateral motor cortices demonstrate reduced inhibition. The data suggest that unimanual movement decreases inhibition bi-directionally across motor hemispheres and offer one explanation for the observation of ipsilateral M1 activity during hand movements.

  20. Improving Leung's bidirectional learning rule for associative memories.

    Science.gov (United States)

    Lenze, B

    2001-01-01

    Leung (1994) introduced a perceptron-like learning rule to enhance the recall performance of bidirectional associative memories (BAMs). He proved that his so-called bidirectional learning scheme always yields a solution within a finite number of learning iterations in case that a solution exists. Unfortunately, in the setting of Leung a solution only exists in case that the training set is strongly linear separable by hyperplanes through the origin. We extend Leung's approach by considering conditionally strong linear separable sets allowing separating hyperplanes not containing the origin. Moreover, we deal with BAMs, which are generalized by defining so-called dilation and translation parameters enlarging their capacity, while leaving their complexity almost unaffected. The whole approach leads to a generalized bidirectional learning rule which generates BAMs with dilation and translation that perform perfectly on the training set in a case that the latter satisfies the conditionally strong linear separability assumption. Therefore, in the sense of Leung, we conclude with an optimal learning strategy which contains Leung's initial idea as a special case.

  1. Bidirectional Promoter Engineering for Single Cell MicroRNA Sensors in Embryonic Stem Cells.

    Science.gov (United States)

    Sladitschek, Hanna L; Neveu, Pierre A

    2016-01-01

    MicroRNAs have emerged as important markers and regulators of cell identity. Precise measurements of cellular miRNA levels rely traditionally on RNA extraction and thus do not allow to follow miRNA expression dynamics at the level of single cells. Non-invasive miRNA sensors present an ideal solution but they critically depend on the performance of suitable ubiquitous promoters that reliably drive expression both in pluripotent and differentiated cell types. Here we describe the engineering of bidirectional promoters that drive the expression of precise ratiometric fluorescent miRNA sensors in single mouse embryonic stem cells (mESCs) and their differentiated derivatives. These promoters are based on combinations of the widely used CAG, EF1α and PGK promoters as well as the CMV and PGK enhancers. miR-142-3p, which is known to be bimodally expressed in mESCs, served as a model miRNA to gauge the precision of the sensors. The performance of the resulting miRNA sensors was assessed by flow cytometry in single stable transgenic mESCs undergoing self-renewal or differentiation. EF1α promoters arranged back-to-back failed to drive the robustly correlated expression of two transgenes. Back-to-back PGK promoters were shut down during mESC differentiation. However, we found that a back-to-back arrangement of CAG promoters with four CMV enhancers provided both robust expression in mESCs undergoing differentiation and the best signal-to-noise for measurement of miRNA activity in single cells among all the sensors we tested. Such a bidirectional promoter is therefore particularly well suited to study the dynamics of miRNA expression during cell fate transitions at the single cell level.

  2. Bidirectional Promoter Engineering for Single Cell MicroRNA Sensors in Embryonic Stem Cells.

    Directory of Open Access Journals (Sweden)

    Hanna L Sladitschek

    Full Text Available MicroRNAs have emerged as important markers and regulators of cell identity. Precise measurements of cellular miRNA levels rely traditionally on RNA extraction and thus do not allow to follow miRNA expression dynamics at the level of single cells. Non-invasive miRNA sensors present an ideal solution but they critically depend on the performance of suitable ubiquitous promoters that reliably drive expression both in pluripotent and differentiated cell types. Here we describe the engineering of bidirectional promoters that drive the expression of precise ratiometric fluorescent miRNA sensors in single mouse embryonic stem cells (mESCs and their differentiated derivatives. These promoters are based on combinations of the widely used CAG, EF1α and PGK promoters as well as the CMV and PGK enhancers. miR-142-3p, which is known to be bimodally expressed in mESCs, served as a model miRNA to gauge the precision of the sensors. The performance of the resulting miRNA sensors was assessed by flow cytometry in single stable transgenic mESCs undergoing self-renewal or differentiation. EF1α promoters arranged back-to-back failed to drive the robustly correlated expression of two transgenes. Back-to-back PGK promoters were shut down during mESC differentiation. However, we found that a back-to-back arrangement of CAG promoters with four CMV enhancers provided both robust expression in mESCs undergoing differentiation and the best signal-to-noise for measurement of miRNA activity in single cells among all the sensors we tested. Such a bidirectional promoter is therefore particularly well suited to study the dynamics of miRNA expression during cell fate transitions at the single cell level.

  3. Activity-Dependent Bidirectional Regulation of GAD Expression in a Homeostatic Fashion Is Mediated by BDNF-Dependent and Independent Pathways.

    Science.gov (United States)

    Hanno-Iijima, Yoko; Tanaka, Masami; Iijima, Takatoshi

    2015-01-01

    Homeostatic synaptic plasticity, or synaptic scaling, is a mechanism that tunes neuronal transmission to compensate for prolonged, excessive changes in neuronal activity. Both excitatory and inhibitory neurons undergo homeostatic changes based on synaptic transmission strength, which could effectively contribute to a fine-tuning of circuit activity. However, gene regulation that underlies homeostatic synaptic plasticity in GABAergic (GABA, gamma aminobutyric) neurons is still poorly understood. The present study demonstrated activity-dependent dynamic scaling in which NMDA-R (N-methyl-D-aspartic acid receptor) activity regulated the expression of GABA synthetic enzymes: glutamic acid decarboxylase 65 and 67 (GAD65 and GAD67). Results revealed that activity-regulated BDNF (brain-derived neurotrophic factor) release is necessary, but not sufficient, for activity-dependent up-scaling of these GAD isoforms. Bidirectional forms of activity-dependent GAD expression require both BDNF-dependent and BDNF-independent pathways, both triggered by NMDA-R activity. Additional results indicated that these two GAD genes differ in their responsiveness to chronic changes in neuronal activity, which could be partially caused by differential dependence on BDNF. In parallel to activity-dependent bidirectional scaling in GAD expression, the present study further observed that a chronic change in neuronal activity leads to an alteration in neurotransmitter release from GABAergic neurons in a homeostatic, bidirectional fashion. Therefore, the differential expression of GAD65 and 67 during prolonged changes in neuronal activity may be implicated in some aspects of bidirectional homeostatic plasticity within mature GABAergic presynapses.

  4. Research on a Novel Power Inductor-Based Bidirectional Lossless Equalization Circuit for Series-Connected Battery Packs

    Directory of Open Access Journals (Sweden)

    Xiangwei Guo

    2015-06-01

    Full Text Available Cell balancing plays an important role in preserving the life of series-connected battery packs; without a suitable balancing system, the individual cell voltages will differ over time, and the battery pack capacity will decrease quickly. This paper presents a novel power inductor-based bidirectional lossless equalization circuit. This circuit consists of several balancing sub-circuits, which allow the dynamic adjustment of the equalization path and equalization threshold. The simulation and experiment results demonstrate that the proposed circuit, which features a simple control method, fast balancing, and a large equalization current, exhibits outstanding equalization performance.

  5. The PRR11-SKA2 Bidirectional Transcription Unit Is Negatively Regulated by p53 through NF-Y in Lung Cancer Cells.

    Science.gov (United States)

    Wang, Yitao; Weng, Huali; Zhang, Ying; Long, Yinjiang; Li, Yi; Niu, Yulong; Song, Fangzhou; Bu, Youquan

    2017-03-01

    We previously identified proline-rich protein 11 (PRR11) as a novel cancer-related gene that is implicated in the regulation of cell cycle and tumorigenesis. Our recent study demonstrated that PRR11 and its adjacent gene, kinetochore associated 2 (SKA2), constitute a classic head-to-head gene pair that is coordinately regulated by nuclear factor Y (NF-Y). In the present study, we further show that the PRR11-SKA2 bidirectional transcription unit is an indirect target of the tumor suppressor p53. A luciferase reporter assay revealed that overexpression of wild type p53, but not mutant p53, significantly represses the basal activity and NF-Y mediated transactivation of the PRR11-SKA2 bidirectional promoter. Deletion and mutation analysis of the PRR11-SKA2 promoter revealed that p53-mediated PRR11-SKA2 repression is dependent on the presence of functional NF-Y binding sites. Furthermore, a co-immunoprecipitation assay revealed that p53 associates with NF-Y in lung cancer cells, and a chromatin immunoprecipitation assay showed that p53 represses PRR11-SKA2 transcription by reducing the binding amount of NF-Y in the PRR11-SKA2 promoter region. Consistently, the ability of p53 to downregulate PRR11-SKA2 transcription was significantly attenuated upon siRNA-mediated depletion of nuclear factor Y subunit beta (NF-YB). Notably, lung cancer patients with lower expression of either PRR11 or SKA2 along with wild type p53 exhibited the best overall survival compared with others with p53 mutation and/or higher expression of either PRR11 or SKA2. Taken together, our results demonstrate that p53 negatively regulates the expression of the PRR11-SKA2 bidirectional transcription unit through NF-Y, suggesting that the inability to repress the PRR11-SKA2 bidirectional transcription unit after loss of p53 might contribute to tumorigenesis.

  6. A Bidirectional “Y” Type OXC Structure Using the Least Optical Switches

    Institute of Scientific and Technical Information of China (English)

    TAO Zhenning; WU Deming; XU Anshi

    2000-01-01

    In this paper, a bidirectional Y type optical cross-connect structure is introduced. It minimizes the number of 2 × 2 optical switches by utilizing the route characteristic of a bidirectional Y type OTN node. The method to satisfy this route request by our OXC is demonstrated. The wavelength utilizing efficiency between our structure and the nonblocking bidirectional Y type OTN node has also compared. The blocking, complexity, loss, loss uniformity and cross-talk characteristics are also demonstrated.

  7. Evaluation of Bidirectional Silicon Carbide Solid-State Circuit Breaker v3.2

    Science.gov (United States)

    2013-07-01

    Evaluation of Bidirectional Silicon Carbide Solid-State Circuit Breaker v3.2 by D. Urciuoli ARL-MR-0845 July 2013...Evaluation of Bidirectional Silicon Carbide Solid-State Circuit Breaker v3.2 D. Urciuoli Sensors and Electron Devices Directorate, ARL...2012 to 20 March 2013 4. TITLE AND SUBTITLE Evaluation of Bidirectional Silicon Carbide Solid-State Circuit Breaker v3.2 5a. CONTRACT NUMBER 5b

  8. Dynamic Isotope Power System (DIPS) Applications Study. Volume II. Nuclear Integrated Multimission Spacecraft (NIMS) design definition. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Prickett, W. Z.

    1979-11-01

    The design requirements for the Nuclear Integrated Multimission Spacecraft. (NIMS) are discussed in detail. The requirements are a function of mission specifications, payload, control system requirements, electric system specifications, and cost limitations. (LCL)

  9. Bidirectional MIMO Channel Tracking Based on PASTd and Performance Evaluation

    Science.gov (United States)

    Ehrenberg, Livnat; Gannot (Eurasipmember), Sharon; Shayevitz, Ofer; Leshem, Amir; Zehavi, Ephraim

    2010-12-01

    We consider a bidirectional time division duplex (TDD) multiple-input multiple-output (MIMO) communication system with time-varying channel and additive white Gaussian noise (AWGN). A blind bidirectional channel tracking algorithm, based on the projection approximation subspace tracking (PAST) algorithm, is applied in both terminals. The resulting singular value decomposition (SVD) of the channel matrix is then used to approximately diagonalize the channel. The proposed method is applied to an orthogonal frequency-division multiplexing-(OFDM-)MIMO setting with a typical indoor time-domain reflection model. The computational cost of the proposed algorithm, compared with other state-of-the-art algorithms, is relatively small. The Kalman filter is utilized for establishing a benchmark for the obtained performance of the proposed tracking algorithm. The performance degradation relative to a full channel state information (CSI) due to the application of the tracking algorithm is evaluated in terms of average effective rate and the outage probability and compared with alternative tracking algorithms. The obtained results are also compared with a benchmark obtained by the Kalman filter with known input signal and channel characteristics. It is shown that the expected degradation in performance of frequency-domain algorithms (which do not exploit the smooth frequency response of the channel) is only minor compared with time-domain algorithms in a range of reasonable signal-to-noise ratio (SNR) levels. The proposed bidirectional frequency-domain tracking algorithm, proposed in this paper, is shown to attain communication rates close to the benchmark and to outperform a competing algorithm. The paper is concluded by evaluating the proposed blind tracking method in terms of the outage probability and the symbol error rate (SER) versus. SNR for binary phase shift keying (BPSK) and 4-Quadrature amplitude modulation (QAM) constellations.

  10. Bidirectional MIMO Channel Tracking Based on PASTd and Performance Evaluation

    Directory of Open Access Journals (Sweden)

    Shayevitz Ofer

    2010-01-01

    Full Text Available Abstract We consider a bidirectional time division duplex (TDD multiple-input multiple-output (MIMO communication system with time-varying channel and additive white Gaussian noise (AWGN. A blind bidirectional channel tracking algorithm, based on the projection approximation subspace tracking (PAST algorithm, is applied in both terminals. The resulting singular value decomposition (SVD of the channel matrix is then used to approximately diagonalize the channel. The proposed method is applied to an orthogonal frequency-division multiplexing-(OFDM-MIMO setting with a typical indoor time-domain reflection model. The computational cost of the proposed algorithm, compared with other state-of-the-art algorithms, is relatively small. The Kalman filter is utilized for establishing a benchmark for the obtained performance of the proposed tracking algorithm. The performance degradation relative to a full channel state information (CSI due to the application of the tracking algorithm is evaluated in terms of average effective rate and the outage probability and compared with alternative tracking algorithms. The obtained results are also compared with a benchmark obtained by the Kalman filter with known input signal and channel characteristics. It is shown that the expected degradation in performance of frequency-domain algorithms (which do not exploit the smooth frequency response of the channel is only minor compared with time-domain algorithms in a range of reasonable signal-to-noise ratio (SNR levels. The proposed bidirectional frequency-domain tracking algorithm, proposed in this paper, is shown to attain communication rates close to the benchmark and to outperform a competing algorithm. The paper is concluded by evaluating the proposed blind tracking method in terms of the outage probability and the symbol error rate (SER versus. SNR for binary phase shift keying (BPSK and 4-Quadrature amplitude modulation (QAM constellations.

  11. Study of bidirectional broadband passive optical network (BPON) using EDFA

    Science.gov (United States)

    Almalaq, Yasser

    Optical line terminals (OLTs) and number of optical network units (ONUs) are two main parts of passive optical network (PON). OLT is placed at the central office of the service providers, the ONUs are located near to the end subscribers. When compared with point-to-point design, a PON decreases the number of fiber used and central office components required. Broadband PON (BPON), which is one type of PON, can support high-speed voice, data and video services to subscribers' residential homes and small businesses. In this research, by using erbium doped fiber amplifier (EDFA), the performance of bi-directional BPON is experimented and tested for both downstream and upstream traffic directions. Ethernet PON (E-PON) and gigabit PON (G-PON) are the two other kinds of passive optical network besides BPON. The most beneficial factor of using BPON is it's reduced cost. The cost of the maintenance between the central office and the users' side is suitable because of the use of passive components, such as a splitter in the BPON architecture. In this work, a bidirectional BPON has been analyzed for both downstream and upstream cases by using bit error rate analyzer (BER). BER analyzers test three factors that are the maximum Q factor, minimum bit error rate, and eye height. In other words, parameters such as maximum Q factor, minimum bit error rate, and eye height can be analyzed utilized a BER tester. Passive optical components such as a splitter, optical circulator, and filters have been used in modeling and simulations. A 12th edition Optiwave simulator has been used in order to analyze the bidirectional BPON system. The system has been tested under several conditions such as changing the fiber length, extinction ratio, dispersion, and coding technique. When a long optical fiber above 40km was used, an EDFA was used in order to improve the quality of the signal.

  12. An Experimental Investigation of the Responses of Classic Spar Platform Subjected to Bi-directional Waves

    Directory of Open Access Journals (Sweden)

    V.J. Kurian

    2015-01-01

    Full Text Available The effect of the bi-directional short-crested waves on the dynamic motion responses of the moored classic spar is demonstrated from the results of the models test in this study. Practically in the design of offshore structures, long-crested or 2-dimensional wave properties that propagated to one direction are considered. Even though such long-crested wave is widely used for the design purposes, it is hardly determined in the real sea. The wind generated sea state in the real sea conditions are indeed well represented by the short-crested waves. Short-crested waves are defined as linear summation of long-crested wave series that propagated to different directions. Hence, the motions of the model were investigated experimentally by conducting the wave tank tests in the wave tank of Offshore Laboratory of Universiti Teknologi PETRONAS. Five groups of bi-directional wave series were defined and exerted on the classic spar model, which fabricated by using steel with scaling factor of 1:100. From the results measured, it was found that similar trends of the responses in term of Response Amplitude Operator (RAO for surge, heave and pitch motions were obtained. Maximum responses of surge, heave and pitch were found due to wave crossing angle 90°, while minimum response was found due to wave crossing angle 135°, respectively. It could be concluded that the wave crossing angle 90° (BD3 gives the widest spreading for short crested waves, while the wave crossing angle 135° (BD4 gives the narrowest spreading for short crested waves.

  13. A bidirectional brain-machine interface algorithm that approximates arbitrary force-fields.

    Directory of Open Access Journals (Sweden)

    Alessandro Vato

    Full Text Available We examine bidirectional brain-machine interfaces that control external devices in a closed loop by decoding motor cortical activity to command the device and by encoding the state of the device by delivering electrical stimuli to sensory areas. Although it is possible to design this artificial sensory-motor interaction while maintaining two independent channels of communication, here we propose a rule that closes the loop between flows of sensory and motor information in a way that approximates a desired dynamical policy expressed as a field of forces acting upon the controlled external device. We previously developed a first implementation of this approach based on linear decoding of neural activity recorded from the motor cortex into a set of forces (a force field applied to a point mass, and on encoding of position of the point mass into patterns of electrical stimuli delivered to somatosensory areas. However, this previous algorithm had the limitation that it only worked in situations when the position-to-force map to be implemented is invertible. Here we overcome this limitation by developing a new non-linear form of the bidirectional interface that can approximate a virtually unlimited family of continuous fields. The new algorithm bases both the encoding of position information and the decoding of motor cortical activity on an explicit map between spike trains and the state space of the device computed with Multi-Dimensional-Scaling. We present a detailed computational analysis of the performance of the interface and a validation of its robustness by using synthetic neural responses in a simulated sensory-motor loop.

  14. Bidirectional converter interface for a battery energy storage test bench

    DEFF Research Database (Denmark)

    Trintis, Ionut; Thomas, Stephan; Blank, Tobias;

    2011-01-01

    This paper presents the bidirectional converter interface for a 6 kV battery energy storage test bench. The power electronic interface consists a two stage converter topology having a low voltage dc-ac grid connected converter and a new dual active bridge dc-dc converter with high transformation...... ratio. The dc-dc converter controls the battery charge/discharge current while the grid converter controls the common dc-link voltage and the grid current. The applied control structures and the hardware implementation of both converters are presented, together with their interaction. Experimental...

  15. Bidirectional invisibility in Kramers-Kronig optical media

    CERN Document Server

    Longhi, Stefano

    2016-01-01

    A broad class of planar dielectric media with complex permittivity profiles that are fully invisible, for both left and right incidence sides, is introduced. Such optical media are locally isotropic, non-magnetic and belong to the recently discovered class of Kramers-Kronig media [{\\it Nature Photon.} 9, 436 (2015)], i.e. the spatial profiles of the real and imaginary parts of the dielectric permittivity are related each other by a Hilbert transform. The transition from unidirectional to bidirectional invisibility, and the possibility to realize sharp reflection above a cut-off incidence angle, are also discussed.

  16. Primary Parallel Isolated Boost Converter with Bidirectional Operation

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Mira Albert, Maria del Carmen; Sen, Gökhan;

    2012-01-01

    This paper presents a bidirectional dc/dc converter operated with batteries both in the input and output. Primary parallel isolated boost converter (PPIBC) with transformer series connection on the high voltage side is preferred due to its ability to handle high currents in the low voltage side....... The converter has been modeled using non-ideal components and operated without any additional circuitry for startup using a digital soft-start procedure. Simulated and measured loop gains have been compared for the validity of the model. On-the-fly current direction change has been achieved between input...

  17. Model of a specialized bidirectional dictionary for German and Portuguese

    OpenAIRE

    Ciossek, Catharina Victoria

    2012-01-01

    Dissertação apresentada para cumprimento dos requisitos necessários à obtenção do grau de Mestre em Terminologia e Gestão da Informação de Especialidade The scope of this thesis is the process of establishing a specialized, bilingual, bidirectional dictionary of the medical area of dermatology that could facilitate the work of dermatologists, professionals of the area of dermatology and also researchers and translators that are working with the specialized language of dermatology. It will ...

  18. Bidirectional private key exchange using delay-coupled semiconductor lasers.

    Science.gov (United States)

    Porte, Xavier; Soriano, Miguel C; Brunner, Daniel; Fischer, Ingo

    2016-06-15

    We experimentally demonstrate a key exchange cryptosystem based on the phenomenon of identical chaos synchronization. In our protocol, the private key is symmetrically generated by the two communicating partners. It is built up from the synchronized bits occurring between two current-modulated bidirectionally coupled semiconductor lasers with additional self-feedback. We analyze the security of the exchanged key and discuss the amplification of its privacy. We demonstrate private key generation rates up to 11  Mbit/s over a public channel.

  19. Bidirectional invisibility in Kramers-Kronig optical media

    Science.gov (United States)

    Longhi, S.

    2016-08-01

    A broad class of planar dielectric media with complex permittivity profiles that are fully invisible, for both left and right incidence sides, is introduced. Such optical media are locally isotropic, non-magnetic and belong to the recently discovered class of Kramers-Kronig media [{\\it Nature Photon.} 9, 436 (2015)], i.e. the spatial profiles of the real and imaginary parts of the dielectric permittivity are related each other by a Hilbert transform. The transition from unidirectional to bidirectional invisibility, and the possibility to realize sharp reflection above a cut-off incidence angle, are also discussed.

  20. A New Hard Switching Bidirectional Converter With High Power Density

    Directory of Open Access Journals (Sweden)

    Bahador Fani

    2010-01-01

    Full Text Available In this paper, a new isolated dc-dc bidirectional converter is proposed. This converter consists of two transformers (flyback and forward and only one switch in primary side and one switch in secondary side of transformers. In this converter energy transfers to the output in both on and off switch states so power density of this converter is high This converter controlled by PWM signal. Also this converter operates over a wide input voltage range. Theoretical analysis is presented and computer simulation and experimental results verify the converter analysis.

  1. Bi-Directional DC-DC Converter for PHEV Applications

    Energy Technology Data Exchange (ETDEWEB)

    Abas Goodarzi

    2011-01-31

    Plug-In Hybrid Electric Vehicles (PHEV) require high power density energy storage system (ESS) for hybrid operation and high energy density ESS for Electric Vehicle (EV) mode range. However, ESS technologies to maximize power density and energy density simultaneously are not commercially feasible. The use of bi-directional DC-DC converter allows use of multiple energy storage, and the flexible DC-link voltages can enhance the system efficiency and reduce component sizing. This will improve fuel consumption, increase the EV mode range, reduce the total weight, reduce battery initial and life cycle cost, and provide flexibility in system design.

  2. Efficient reconstruction of metabolic pathways by bidirectional chemical search.

    Science.gov (United States)

    Félix, Liliana; Rosselló, Francesc; Valiente, Gabriel

    2009-04-01

    One of the main challenges in systems biology is the establishment of the metabolome: a catalogue of the metabolites and biochemical reactions present in a specific organism. Current knowledge of biochemical pathways as stored in public databases such as KEGG, is based on carefully curated genomic evidence for the presence of specific metabolites and enzymes that activate particular biochemical reactions. In this paper, we present an efficient method to build a substantial portion of the artificial chemistry defined by the metabolites and biochemical reactions in a given metabolic pathway, which is based on bidirectional chemical search. Computational results on the pathways stored in KEGG reveal novel biochemical pathways.

  3. Hopf bifurcation of an (n + 1) -neuron bidirectional associative memory neural network model with delays.

    Science.gov (United States)

    Xiao, Min; Zheng, Wei Xing; Cao, Jinde

    2013-01-01

    Recent studies on Hopf bifurcations of neural networks with delays are confined to simplified neural network models consisting of only two, three, four, five, or six neurons. It is well known that neural networks are complex and large-scale nonlinear dynamical systems, so the dynamics of the delayed neural networks are very rich and complicated. Although discussing the dynamics of networks with a few neurons may help us to understand large-scale networks, there are inevitably some complicated problems that may be overlooked if simplified networks are carried over to large-scale networks. In this paper, a general delayed bidirectional associative memory neural network model with n + 1 neurons is considered. By analyzing the associated characteristic equation, the local stability of the trivial steady state is examined, and then the existence of the Hopf bifurcation at the trivial steady state is established. By applying the normal form theory and the center manifold reduction, explicit formulae are derived to determine the direction and stability of the bifurcating periodic solution. Furthermore, the paper highlights situations where the Hopf bifurcations are particularly critical, in the sense that the amplitude and the period of oscillations are very sensitive to errors due to tolerances in the implementation of neuron interconnections. It is shown that the sensitivity is crucially dependent on the delay and also significantly influenced by the feature of the number of neurons. Numerical simulations are carried out to illustrate the main results.

  4. Advanced fuel cycle cost estimation model and its cost estimation results for three nuclear fuel cycles using a dynamic model in Korea

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sungki, E-mail: sgkim1@kaeri.re.kr [Korea Atomic Energy Research Institute, 1045 Daedeokdaero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Ko, Wonil [Korea Atomic Energy Research Institute, 1045 Daedeokdaero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Youn, Saerom; Gao, Ruxing [University of Science and Technology, 217 Gajungro, Yuseong-gu, Daejeon 305-350 (Korea, Republic of); Bang, Sungsig, E-mail: ssbang@kaist.ac.kr [Korea Advanced Institute of Science and Technology, Department of Business and Technology Management, 291 Deahak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2015-11-15

    Highlights: • The nuclear fuel cycle cost using a new cost estimation model was analyzed. • The material flows of three nuclear fuel cycle options were calculated. • The generation cost of once-through was estimated to be 66.88 mills/kW h. • The generation cost of pyro-SFR recycling was estimated to be 78.06 mills/kW h. • The reactor cost was identified as the main cost driver of pyro-SFR recycling. - Abstract: The present study analyzes advanced nuclear fuel cycle cost estimation models such as the different discount rate model and its cost estimation results. To do so, an analysis of the nuclear fuel cycle cost of three options (direct disposal (once through), PWR–MOX (Mixed OXide fuel), and Pyro-SFR (Sodium-cooled Fast Reactor)) from the viewpoint of economic sense, focusing on the cost estimation model, was conducted using a dynamic model. From an analysis of the fuel cycle cost estimation results, it was found that some cost gap exists between the traditional same discount rate model and the advanced different discount rate model. However, this gap does not change the priority of the nuclear fuel cycle option from the viewpoint of economics. In addition, the fuel cycle costs of OT (Once-Through) and Pyro-SFR recycling based on the most likely value using a probabilistic cost estimation except for reactor costs were calculated to be 8.75 mills/kW h and 8.30 mills/kW h, respectively. Namely, the Pyro-SFR recycling option was more economical than the direct disposal option. However, if the reactor cost is considered, the economic sense in the generation cost between the two options (direct disposal vs. Pyro-SFR recycling) can be changed because of the high reactor cost of an SFR.

  5. FE65 regulates and interacts with the Bloom syndrome protein in dynamic nuclear spheres - potential relevance to Alzheimer's disease.

    Science.gov (United States)

    Schrötter, Andreas; Mastalski, Thomas; Nensa, Fabian M; Neumann, Martin; Loosse, Christina; Pfeiffer, Kathy; Magraoui, Fouzi El; Platta, Harald W; Erdmann, Ralf; Theiss, Carsten; Uszkoreit, Julian; Eisenacher, Martin; Meyer, Helmut E; Marcus, Katrin; Müller, Thorsten

    2013-06-01

    The intracellular domain of the amyloid precursor protein (AICD) is generated following cleavage of the precursor by the γ-secretase complex and is involved in membrane to nucleus signaling, for which the binding of AICD to the adapter protein FE65 is essential. Here we show that FE65 knockdown causes a downregulation of the protein Bloom syndrome protein (BLM) and the minichromosome maintenance (MCM) protein family and that elevated nuclear levels of FE65 result in stabilization of the BLM protein in nuclear mobile spheres. These spheres are able to grow and fuse, and potentially correspond to the nuclear domain 10. BLM plays a role in DNA replication and repair mechanisms and FE65 was also shown to play a role in DNA damage response in the cell. A set of proliferation assays in our work revealed that FE65 knockdown in HEK293T cells reduced cell replication. On the basis of these results, we hypothesize that nuclear FE65 levels (nuclear FE65/BLM containing spheres) may regulate cell cycle re-entry in neurons as a result of increased interaction of FE65 with BLM and/or an increase in MCM protein levels. Thus, FE65 interactions with BLM and MCM proteins may contribute to the neuronal cell cycle re-entry observed in brains affected by Alzheimer's disease.

  6. Modeling of hydrogen/deuterium dynamics and heat generation on palladium nanoparticles for hydrogen storage and solid-state nuclear fusion

    Directory of Open Access Journals (Sweden)

    Katsuaki Tanabe

    2016-01-01

    Full Text Available We modeled the dynamics of hydrogen and deuterium adsorbed on palladium nanoparticles including the heat generation induced by the chemical adsorption and desorption, as well as palladium-catalyzed reactions. Our calculations based on the proposed model reproduce the experimental time-evolution of pressure and temperature with a single set of fitting parameters for hydrogen and deuterium injection. The model we generated with a highly generalized set of formulations can be applied for any combination of a gas species and a catalytic adsorbent/absorbent. Our model can be used as a basis for future research into hydrogen storage and solid-state nuclear fusion technologies.

  7. Modeling of hydrogen/deuterium dynamics and heat generation on palladium nanoparticles for hydrogen storage and solid-state nuclear fusion.

    Science.gov (United States)

    Tanabe, Katsuaki

    2016-01-01

    We modeled the dynamics of hydrogen and deuterium adsorbed on palladium nanoparticles including the heat generation induced by the chemical adsorption and desorption, as well as palladium-catalyzed reactions. Our calculations based on the proposed model reproduce the experimental time-evolution of pressure and temperature with a single set of fitting parameters for hydrogen and deuterium injection. The model we generated with a highly generalized set of formulations can be applied for any combination of a gas species and a catalytic adsorbent/absorbent. Our model can be used as a basis for future research into hydrogen storage and solid-state nuclear fusion technologies.

  8. 1H nuclear magnetic resonance study of low-temperature water dynamics in a water-soaked perfluorosulfonic acid ionomer Nafion film

    Science.gov (United States)

    Han, Jun Hee; Lee, Kyu Won; Lee, Cheol Eui

    2017-01-01

    We have employed proton nuclear magnetic resonance (NMR) spectroscopy in order to study the low-temperature water dynamics in a water-soaked perfluorosulfonic acid ionomer Nafion (NR-211) film. According to the recent models, Nafion may comprise water strongly bound to the sulfonic acid group, hydration water, and condensed water species. In this work, three separate NMR peaks from the water species revealing distinct behaviors were identified. A significant portion of the "bound" water remained unfrozen down to 200 K, whereas a slow-to-fast motional limit transition was observed at TM=220 K from the relaxation measurements.

  9. The Bidirectional Relationship between Sleep and Immunity against Infections.

    Science.gov (United States)

    Ibarra-Coronado, Elizabeth G; Pantaleón-Martínez, Ana Ma; Velazquéz-Moctezuma, Javier; Prospéro-García, Oscar; Méndez-Díaz, Mónica; Pérez-Tapia, Mayra; Pavón, Lenin; Morales-Montor, Jorge

    2015-01-01

    Sleep is considered an important modulator of the immune response. Thus, a lack of sleep can weaken immunity, increasing organism susceptibility to infection. For instance, shorter sleep durations are associated with a rise in suffering from the common cold. The function of sleep in altering immune responses must be determined to understand how sleep deprivation increases the susceptibility to viral, bacterial, and parasitic infections. There are several explanations for greater susceptibility to infections after reduced sleep, such as impaired mitogenic proliferation of lymphocytes, decreased HLA-DR expression, the upregulation of CD14+, and variations in CD4+ and CD8+ T lymphocytes, which have been observed during partial sleep deprivation. Also, steroid hormones, in addition to regulating sexual behavior, influence sleep. Thus, we hypothesize that sleep and the immune-endocrine system have a bidirectional relationship in governing various physiological processes, including immunity to infections. This review discusses the evidence on the bidirectional effects of the immune response against viral, bacterial, and parasitic infections on sleep patterns and how the lack of sleep affects the immune response against such agents. Because sleep is essential in the maintenance of homeostasis, these situations must be adapted to elicit changes in sleep patterns and other physiological parameters during the immune response to infections to which the organism is continuously exposed.

  10. Bidirectional Microglia-Neuron Communication in the Healthy Brain

    Directory of Open Access Journals (Sweden)

    Ukpong B. Eyo

    2013-01-01

    Full Text Available Unlike other resident neural cells that are of neuroectodermal origin, microglia are resident neural cells of mesodermal origin. Traditionally recognized for their immune functions during disease, new roles are being attributed to these cells in the development and maintenance of the central nervous system (CNS including specific communication with neurons. In this review, we highlight some of the recent findings on the bidirectional interaction between neurons and microglia. We discuss these interactions along two lines. First, we review data that suggest that microglial activity is modulated by neuronal signals, focusing on evidence that (i neurons are capable of regulating microglial activation state and influence basal microglial activities; (ii classic neurotransmitters affect microglial behavior; (iii chemotactic signals attract microglia during acute neuronal injury. Next, we discuss some of the recent data on how microglia signal to neurons. Signaling mechanisms include (i direct physical contact of microglial processes with neuronal elements; (ii microglial regulation of neuronal synapse and circuit by fractalkine, complement, and DAP12 signaling. In addition, we discuss the use of microglial depletion strategies in studying the role of microglia in neuronal development and synaptic physiology. Deciphering the mechanisms of bidirectional microglial-neuronal communication provides novel insights in understanding microglial function in both the healthy and diseased brain.

  11. The Bidirectional Relationship between Sleep and Immunity against Infections

    Directory of Open Access Journals (Sweden)

    Elizabeth G. Ibarra-Coronado

    2015-01-01

    Full Text Available Sleep is considered an important modulator of the immune response. Thus, a lack of sleep can weaken immunity, increasing organism susceptibility to infection. For instance, shorter sleep durations are associated with a rise in suffering from the common cold. The function of sleep in altering immune responses must be determined to understand how sleep deprivation increases the susceptibility to viral, bacterial, and parasitic infections. There are several explanations for greater susceptibility to infections after reduced sleep, such as impaired mitogenic proliferation of lymphocytes, decreased HLA-DR expression, the upregulation of CD14+, and variations in CD4+ and CD8+ T lymphocytes, which have been observed during partial sleep deprivation. Also, steroid hormones, in addition to regulating sexual behavior, influence sleep. Thus, we hypothesize that sleep and the immune-endocrine system have a bidirectional relationship in governing various physiological processes, including immunity to infections. This review discusses the evidence on the bidirectional effects of the immune response against viral, bacterial, and parasitic infections on sleep patterns and how the lack of sleep affects the immune response against such agents. Because sleep is essential in the maintenance of homeostasis, these situations must be adapted to elicit changes in sleep patterns and other physiological parameters during the immune response to infections to which the organism is continuously exposed.

  12. Optimization of the assisted bidirectional Glenn for single ventricle palliation

    Science.gov (United States)

    Marsden, Alison; Shang, Jessica; Esmaily-Moghadam, Mahdi; Figliola, Richard; Reinhartz, Olaf; Hsia, Tain-Yen

    2015-11-01

    For neonates with single ventricle physiology, a systemic-pulmonary shunt (e.g., a modified Blalock-Taussig shunt (mBTS)) is typically employed as an early-stage procedure in preparation for a later-stage bidirectional Glenn (BDG). Mortality rates with the mBTS are high, yet the BDG has poorer outcomes in neonates. The assisted bidirectional Glenn (ABG) augments the inadequate pulmonary flow associated with early BDG implementation in neonates through an additional shunt between the innominate artery and the superior vena cava (SVC). The shunt uses a nozzle to inject high-velocity flow to the SVC, elevating downstream pulmonary pressure. Previous simulations and animal studies verified feasibility and higher pulmonary flow rates. In numerical simulations, we explore shunt geometries and placements implanted into a 3D model of the aorta and pulmonary arteries, coupled with a lumped parameter network describing the remaining circulatory system. We seek an ABG shunt that optimizes hemodynamic variables such as pulmonary flow rate and oxygenation and constrains SVC pressure. The optimized ABG will be evaluated against the mBTS and the BDG in simulations and experiments. A successful implementation of the ABG would replace the mBTS and BDG procedures and reduce mortality rates. Burroughs Wellcome Fund, Leducq Foundation.

  13. Pannexin 1 Regulates Bidirectional Hippocampal Synaptic Plasticity in Adult Mice

    Directory of Open Access Journals (Sweden)

    Alvaro O. Ardiles

    2014-10-01

    Full Text Available The threshold for bidirectional modification of synaptic plasticity is known to be controlled by several factors, including the balance between protein phosphorylation and dephosphorylation, postsynaptic free Ca2+ concentration and NMDA receptor (NMDAR composition of GluN2 subunits. Pannexin 1 (Panx1, a member of the integral membrane protein family, has been shown to form non-selective channels and to regulate the induction of synaptic plasticity as well as hippocampal-dependent learning. Although Panx1 channels have been suggested to play a role in excitatory long-term potentiation (LTP, it remains unknown whether these channels also modulate long-term depression (LTD or the balance between both types of synaptic plasticity. To study how Panx1 contributes to excitatory synaptic efficacy, we examined the age-dependent effects of eliminating or blocking Panx1 channels on excitatory synaptic plasticity within the CA1 region of the mouse hippocampus. By using different protocols to induce bidirectional synaptic plasticity, Panx1 channel blockade or lack of Panx1 were found to enhance LTP, whereas both conditions precluded the induction of LTD in adults, but not in young animals. These findings suggest that Panx1 channels restrain the sliding threshold for the induction of synaptic plasticity and underlying brain mechanisms of learning and memory.

  14. The Bidirectional Relationship between Sleep and Immunity against Infections

    Science.gov (United States)

    Ibarra-Coronado, Elizabeth G.; Pantaleón-Martínez, Ana Ma.; Velazquéz-Moctezuma, Javier; Prospéro-García, Oscar; Méndez-Díaz, Mónica; Pérez-Tapia, Mayra; Pavón, Lenin; Morales-Montor, Jorge

    2015-01-01

    Sleep is considered an important modulator of the immune response. Thus, a lack of sleep can weaken immunity, increasing organism susceptibility to infection. For instance, shorter sleep durations are associated with a rise in suffering from the common cold. The function of sleep in altering immune responses must be determined to understand how sleep deprivation increases the susceptibility to viral, bacterial, and parasitic infections. There are several explanations for greater susceptibility to infections after reduced sleep, such as impaired mitogenic proliferation of lymphocytes, decreased HLA-DR expression, the upregulation of CD14+, and variations in CD4+ and CD8+ T lymphocytes, which have been observed during partial sleep deprivation. Also, steroid hormones, in addition to regulating sexual behavior, influence sleep. Thus, we hypothesize that sleep and the immune-endocrine system have a bidirectional relationship in governing various physiological processes, including immunity to infections. This review discusses the evidence on the bidirectional effects of the immune response against viral, bacterial, and parasitic infections on sleep patterns and how the lack of sleep affects the immune response against such agents. Because sleep is essential in the maintenance of homeostasis, these situations must be adapted to elicit changes in sleep patterns and other physiological parameters during the immune response to infections to which the organism is continuously exposed. PMID:26417606

  15. Design of a smart bidirectional actuator for space operation

    Science.gov (United States)

    Saggin, Bortolino; Scaccabarozzi, Diego; Tarbini, Marco; Magni, Marianna; Biffi, Carlo Alberto; Tuissi, Ausonio

    2017-03-01

    A common need for space borne instruments, satellites and planetary exploration payloads is the usage of compact, light and low power actuators. In the recent years, this need has been partially solved by the development of customized solutions with an increasing usage of smart materials. A linear bidirectional actuator based on shape memory alloy technology is presented in this work. The device has been conceived to lock the double-pendulum scanning mechanism of a miniaturized Fourier transform spectrometer for planetary observation. The mechanism class is that of pin pullers, with the pin locking the movable components of the spectrometer during launch and landing phases. The proposed mechanism, differently from available off-the-shelf devices, allows multiple actuations without the need of manual resetting. Moreover, the device requires to be powered only to change its status. An appealing feature of the adopted concept is that the actuation is intrinsically shock-less, a key requirement for deployment of devices sensitive to mechanical vibration and shocks. All these characteristics, in addition to the design flexibility of the proposed concept in terms of achievable forces and strokes, make the designed actuator promising for many different applications, from space to ground. The designed bidirectional actuator provides 0.6 mm stroke and a 50 N preload but it represents just an example of implementation for the proposed concept. Structural design of the functional elastic components and SMA alloy characterization have guided the actuator development. A mockup of the actuator has been manufactured and the predicted performances preliminary validated.

  16. Evolutionary Pseudo-Relaxation Learning Algorithm for Bidirectional Associative Memory

    Institute of Scientific and Technical Information of China (English)

    Sheng-Zhi Du; Zeng-Qiang Chen; Zhu-Zhi Yuan

    2005-01-01

    This paper analyzes the sensitivity to noise in BAM (Bidirectional Associative Memory), and then proves the noise immunity of BAM relates not only to the minimum absolute value of net inputs (MAV) but also to the variance of weights associated with synapse connections. In fact, it is a positive monotonically increasing function of the quotient of MAV divided by the variance of weights. Besides, the performance of pseudo-relaxation method depends on learning parameters (λ and ζ), but the relation of them is not linear. So it is hard to find a best combination of λ and ζ which leads to the best BAM performance. And it is obvious that pseudo-relaxation is a kind of local optimization method, so it cannot guarantee to get the global optimal solution. In this paper, a novel learning algorithm EPRBAM (evolutionary psendo-relaxation learning algorithm for bidirectional association memory) employing genetic algorithm and pseudo-relaxation method is proposed to get feasible solution of BAM weight matrix. This algorithm uses the quotient as the fitness of each individual and employs pseudo-relaxation method to adjust individual solution when it does not satisfy constraining condition any more after genetic operation. Experimental results show this algorithm improves noise immunity of BAM greatly. At the same time, EPRBAM does not depend on learning parameters and can get global optimal solution.

  17. Pannexin 1 regulates bidirectional hippocampal synaptic plasticity in adult mice

    Science.gov (United States)

    Ardiles, Alvaro O.; Flores-Muñoz, Carolina; Toro-Ayala, Gabriela; Cárdenas, Ana M.; Palacios, Adrian G.; Muñoz, Pablo; Fuenzalida, Marco; Sáez, Juan C.; Martínez, Agustín D.

    2014-01-01

    The threshold for bidirectional modification of synaptic plasticity is known to be controlled by several factors, including the balance between protein phosphorylation and dephosphorylation, postsynaptic free Ca2+ concentration and NMDA receptor (NMDAR) composition of GluN2 subunits. Pannexin 1 (Panx1), a member of the integral membrane protein family, has been shown to form non-selective channels and to regulate the induction of synaptic plasticity as well as hippocampal-dependent learning. Although Panx1 channels have been suggested to play a role in excitatory long-term potentiation (LTP), it remains unknown whether these channels also modulate long-term depression (LTD) or the balance between both types of synaptic plasticity. To study how Panx1 contributes to excitatory synaptic efficacy, we examined the age-dependent effects of eliminating or blocking Panx1 channels on excitatory synaptic plasticity within the CA1 region of the mouse hippocampus. By using different protocols to induce bidirectional synaptic plasticity, Panx1 channel blockade or lack of Panx1 were found to enhance LTP, whereas both conditions precluded the induction of LTD in adults, but not in young animals. These findings suggest that Panx1 channels restrain the sliding threshold for the induction of synaptic plasticity and underlying brain mechanisms of learning and memory. PMID:25360084

  18. An Improved Multidimensional MPA Procedure for Bidirectional Earthquake Excitations

    Directory of Open Access Journals (Sweden)

    Feng Wang

    2014-01-01

    Full Text Available Presently, the modal pushover analysis procedure is extended to multidimensional analysis of structures subjected to multidimensional earthquake excitations. an improved multidimensional modal pushover analysis (IMMPA method is presented in the paper in order to estimate the response demands of structures subjected to bidirectional earthquake excitations, in which the unidirectional earthquake excitation applied on equivalent SDOF system is replaced by the direct superposition of two components earthquake excitations, and independent analysis in each direction is not required and the application of simplified superposition formulas is avoided. The strength reduction factor spectra based on superposition of earthquake excitations are discussed and compared with the traditional strength reduction factor spectra. The step-by-step procedure is proposed to estimate seismic demands of structures. Two examples are implemented to verify the accuracy of the method, and the results of the examples show that (1 the IMMPA method can be used to estimate the responses of structure subjected to bidirectional earthquake excitations. (2 Along with increase of peak of earthquake acceleration, structural response deviation estimated with the IMMPA method may also increase. (3 Along with increase of the number of total floors of structures, structural response deviation estimated with the IMMPA method may also increase.

  19. Bidirectional Relations between Temperament and Parenting Styles in Chinese Children.

    Science.gov (United States)

    Lee, Erica H; Zhou, Qing; Eisenberg, Nancy; Wang, Yun

    2013-01-01

    The present study examined bidirectional relations between child temperament and parenting styles in a sample (n = 425) of Chinese children during elementary school period (age range = 6 to 9 years at Wave 1). Using two waves (3.8 years apart) of longitudinal data, we tested two hypotheses: (1) whether child temperament (effortful control and anger/frustration) at Wave 1 predicts parenting styles (authoritative and authoritarian parenting) at Wave 2, controlling for Wave 1 parenting; and (2) whether parenting styles at Wave 1 predict Wave 2 temperament, controlling for Wave 1 temperament. We found support for bidirectional relations between temperament and authoritarian parenting, such that higher effortful control and lower anger/frustration were associated with higher authoritarian parenting across time and in both directions. There were no significant cross-time associations between children's temperament and authoritative parenting. These findings extend the previous tests of transactional relations between child temperament and parenting in Chinese children and are consistent with the cultural values toward effortful control and control of anger/frustration in Chinese society.

  20. Axial ligand effects on vibrational dynamics of iron in heme carbonyl studied by nuclear resonance vibrational spectroscopy.

    Science.gov (United States)

    Ohta, Takehiro; Liu, Jin-Gang; Saito, Makina; Kobayashi, Yasuhiro; Yoda, Yoshitaka; Seto, Makoto; Naruta, Yoshinori

    2012-11-29

    Nuclear resonance vibrational spectroscopy (NRVS) and density functional theory calculation (DFT) have been applied to illuminate the effect of axial ligation on the vibrational dynamics of iron in heme carbonyl. The analyses of the NRVS data of five- (5c) and six-coordinate (6c) heme-CO complexes indicate that the prominent feature of (57)Fe partial vibrational density of state ((57)FePVDOS) at the 250-300 cm(-1) region is significantly affected by the association of the axial ligand. The DFT calculations predict that the prominent (57)FePVDOS is composed of iron in-plane motions which are coupled with porphyrin pyrrole in-plane (ν(49), ν(50), and ν(53)), an out-of-plane (γ(8)) (two of four pyrrole rings include the in-plane modes, while the rest of pyrrole rings vibrate along the out-of-plane coordinate), and out-of-phase carbonyl C and O atom displacement perpendicular to the Fe-C-O axis. Thus, in the case of the 5c CO-heme the prominent (57)FePVDOS shows sharp and intense feature because of the degeneracy of the e symmetry mode within the framework of C(4v) symmetry molecule, whereas the association of the axial imidazole ligand in the 6c complex with the lowered symmetry results in split of the degenerate vibrational energy as indicated by broader and lower intensity features of the corresponding NRVS peak compared to the 5c structure. The vibrational energy of the iron in-plane motion in the 6c complex is higher than that in 5c, implying that the iron in the 6c complex includes stronger in-plane interaction with the porphyrin compared to 5c. The iron in-plane mode above 500 cm(-1), which is predominantly coupled with the out-of-phase carbonyl C and O atom motion perpendicular to Fe-C-O, called as Fe-C-O bending mode (δ(Fe-C-O)), also suggests that the 6c structure involves a larger force constant for the e symmetry mode than 5c. The DFT calculations along with the NRVS data suggest that the stiffened iron in-plane motion in the 6c complex can be ascribed