Science.gov

Sample records for modes generator coordinate

  1. Grid-coordinate generation program

    USGS Publications Warehouse

    Cosner, Oliver J.; Horwich, Esther

    1974-01-01

    This program description of the grid-coordinate generation program is written for computer users who are familiar with digital aquifer models. The program computes the coordinates for a variable grid -used in the 'Pinder Model' (a finite-difference aquifer simulator), for input to the CalComp GPCP (general purpose contouring program). The program adjusts the y-value by a user-supplied constant in order to transpose the origin of the model grid from the upper left-hand corner to the lower left-hand corner of the grid. The user has the options of, (1.) choosing the boundaries of the plot; (2.) adjusting the z-values (altitudes) by a constant; (3.) deleting superfluous z-values and (4.) subtracting the simulated surfaces from each other to obtain the decline. Output of this program includes the fixed format CNTL data cards and the other data cards required for input to GPCP. The output from GPCP then is used to produce a potentiometric map or a decline map by means of the CalComp plotter.

  2. Users manual for coordinate generation code CRDSRA

    NASA Technical Reports Server (NTRS)

    Shamroth, S. J.

    1985-01-01

    Generation of a viable coordinate system represents an important component of an isolated airfoil Navier-Stokes calculation. The manual describes a computer code for generation of such a coordinate system. The coordinate system is a general nonorthogonal one in which high resolution normal to the airfoil is obtained in the vicinity of the airfoil surface, and high resolution along the airfoil surface is obtained in the vicinity of the airfoil leading edge. The method of generation is a constructive technique which leads to a C type coordinate grid. The method of construction as well as input and output definitions are contained herein. The computer code itself as well as a sample output is being submitted to COSMIC.

  3. iMODS: internal coordinates normal mode analysis server

    PubMed Central

    López-Blanco, José Ramón; Aliaga, José I.; Quintana-Ortí, Enrique S.; Chacón, Pablo

    2014-01-01

    Normal mode analysis (NMA) in internal (dihedral) coordinates naturally reproduces the collective functional motions of biological macromolecules. iMODS facilitates the exploration of such modes and generates feasible transition pathways between two homologous structures, even with large macromolecules. The distinctive internal coordinate formulation improves the efficiency of NMA and extends its applicability while implicitly maintaining stereochemistry. Vibrational analysis, motion animations and morphing trajectories can be easily carried out at different resolution scales almost interactively. The server is versatile; non-specialists can rapidly characterize potential conformational changes, whereas advanced users can customize the model resolution with multiple coarse-grained atomic representations and elastic network potentials. iMODS supports advanced visualization capabilities for illustrating collective motions, including an improved affine-model-based arrow representation of domain dynamics. The generated all-heavy-atoms conformations can be used to introduce flexibility for more advanced modeling or sampling strategies. The server is free and open to all users with no login requirement at http://imods.chaconlab.org. PMID:24771341

  4. Microgrids and distributed generation systems: Control, operation, coordination and planning

    NASA Astrophysics Data System (ADS)

    Che, Liang

    Distributed Energy Resources (DERs) which include distributed generations (DGs), distributed energy storage systems, and adjustable loads are key components in microgrid operations. A microgrid is a small electric power system integrated with on-site DERs to serve all or some portion of the local load and connected to the utility grid through the point of common coupling (PCC). Microgrids can operate in both grid-connected mode and island mode. The structure and components of hierarchical control for a microgrid at Illinois Institute of Technology (IIT) are discussed and analyzed. Case studies would address the reliable and economic operation of IIT microgrid. The simulation results of IIT microgrid operation demonstrate that the hierarchical control and the coordination strategy of distributed energy resources (DERs) is an effective way of optimizing the economic operation and the reliability of microgrids. The benefits and challenges of DC microgrids are addressed with a DC model for the IIT microgrid. We presented the hierarchical control strategy including the primary, secondary, and tertiary controls for economic operation and the resilience of a DC microgrid. The simulation results verify that the proposed coordinated strategy is an effective way of ensuring the resilient response of DC microgrids to emergencies and optimizing their economic operation at steady state. The concept and prototype of a community microgrid that interconnecting multiple microgrids in a community are proposed. Two works are conducted. For the coordination, novel three-level hierarchical coordination strategy to coordinate the optimal power exchanges among neighboring microgrids is proposed. For the planning, a multi-microgrid interconnection planning framework using probabilistic minimal cut-set (MCS) based iterative methodology is proposed for enhancing the economic, resilience, and reliability signals in multi-microgrid operations. The implementation of high-reliability microgrids

  5. Modes of thrust generation in flying animals

    NASA Astrophysics Data System (ADS)

    Luo, Haoxiang; Song, Jialei; Tobalske, Bret; Luo Team; Tobalske Team

    2016-11-01

    For flying animals in forward flight, thrust is usually much smaller as compared with weight support and has not been given the same amount of attention. Several modes of thrust generation are discussed in this presentation. For insects performing slow flight that is characterized by low advance ratios (i.e., the ratio between flight speed and wing speed), thrust is usually generated by a "backward flick" mode, in which the wings moves upward and backward at a faster speed than the flight speed. Paddling mode is another mode used by some insects like fruit flies who row their wings backward during upstroke like paddles (Ristroph et al., PRL, 2011). Birds wings have high advance ratios and produce thrust during downstroke by directing aerodynamic lift forward. At intermediate advance ratios around one (e.g., hummingbirds and bats), the animal wings generate thrust during both downstroke and upstroke, and thrust generation during upstroke may come at cost of negative weight support. These conclusions are supported by previous experiment studies of insects, birds, and bats, as well as our recent computational modeling of hummingbirds. Supported by the NSF.

  6. Efficient anharmonic vibrational spectroscopy for large molecules using local-mode coordinates.

    PubMed

    Cheng, Xiaolu; Steele, Ryan P

    2014-09-14

    This article presents a general computational approach for efficient simulations of anharmonic vibrational spectra in chemical systems. An automated local-mode vibrational approach is presented, which borrows techniques from localized molecular orbitals in electronic structure theory. This approach generates spatially localized vibrational modes, in contrast to the delocalization exhibited by canonical normal modes. The method is rigorously tested across a series of chemical systems, ranging from small molecules to large water clusters and a protonated dipeptide. It is interfaced with exact, grid-based approaches, as well as vibrational self-consistent field methods. Most significantly, this new set of reference coordinates exhibits a well-behaved spatial decay of mode couplings, which allows for a systematic, a priori truncation of mode couplings and increased computational efficiency. Convergence can typically be reached by including modes within only about 4 Å. The local nature of this truncation suggests particular promise for the ab initio simulation of anharmonic vibrational motion in large systems, where connection to experimental spectra is currently most challenging.

  7. Efficient anharmonic vibrational spectroscopy for large molecules using local-mode coordinates

    NASA Astrophysics Data System (ADS)

    Cheng, Xiaolu; Steele, Ryan P.

    2014-09-01

    This article presents a general computational approach for efficient simulations of anharmonic vibrational spectra in chemical systems. An automated local-mode vibrational approach is presented, which borrows techniques from localized molecular orbitals in electronic structure theory. This approach generates spatially localized vibrational modes, in contrast to the delocalization exhibited by canonical normal modes. The method is rigorously tested across a series of chemical systems, ranging from small molecules to large water clusters and a protonated dipeptide. It is interfaced with exact, grid-based approaches, as well as vibrational self-consistent field methods. Most significantly, this new set of reference coordinates exhibits a well-behaved spatial decay of mode couplings, which allows for a systematic, a priori truncation of mode couplings and increased computational efficiency. Convergence can typically be reached by including modes within only about 4 Å. The local nature of this truncation suggests particular promise for the ab initio simulation of anharmonic vibrational motion in large systems, where connection to experimental spectra is currently most challenging.

  8. Efficient anharmonic vibrational spectroscopy for large molecules using local-mode coordinates

    SciTech Connect

    Cheng, Xiaolu; Steele, Ryan P.

    2014-09-14

    This article presents a general computational approach for efficient simulations of anharmonic vibrational spectra in chemical systems. An automated local-mode vibrational approach is presented, which borrows techniques from localized molecular orbitals in electronic structure theory. This approach generates spatially localized vibrational modes, in contrast to the delocalization exhibited by canonical normal modes. The method is rigorously tested across a series of chemical systems, ranging from small molecules to large water clusters and a protonated dipeptide. It is interfaced with exact, grid-based approaches, as well as vibrational self-consistent field methods. Most significantly, this new set of reference coordinates exhibits a well-behaved spatial decay of mode couplings, which allows for a systematic, a priori truncation of mode couplings and increased computational efficiency. Convergence can typically be reached by including modes within only about 4 Å. The local nature of this truncation suggests particular promise for the ab initio simulation of anharmonic vibrational motion in large systems, where connection to experimental spectra is currently most challenging.

  9. Generator Coordinate Method Analysis of Xe and Ba Isotopes

    NASA Astrophysics Data System (ADS)

    Higashiyama, Koji; Yoshinaga, Naotaka; Teruya, Eri

    Nuclear structure of Xe and Ba isotopes is studied in terms of the quantum-number projected generator coordinate method (GCM). The GCM reproduces well the energy levels of high-spin states as well as low-lying states. The structure of the low-lying states is analyzed through the GCM wave functions.

  10. Distributed Coordination of Energy Storage with Distributed Generators

    SciTech Connect

    Yang, Tao; Wu, Di; Stoorvogel, Antonie A.; Stoustrup, Jakob

    2016-07-18

    With a growing emphasis on energy efficiency and system flexibility, a great effort has been made recently in developing distributed energy resources (DER), including distributed generators and energy storage systems. This paper first formulates an optimal coordination problem considering constraints at both system and device levels, including power balance constraint, generator output limits, storage energy and power capacity and charging/discharging efficiencies. An algorithm is then proposed to dynamically and automatically coordinate DERs in a distributed manner. With the proposed algorithm, the agent at each DER only maintains a local incremental cost and updates it through information exchange with a few neighbors, without relying on any central decision maker. Simulation results are used to illustrate and validate the proposed algorithm.

  11. Illustration of distributed generation effects on protection system coordination

    NASA Astrophysics Data System (ADS)

    Alawami, Hussain Adnan

    Environmental concerns, market forces, and emergence of new technologies have recently resulted in restructuring electric utility from vertically integrated networks to competitive deregulated entities. Distributed generation (DG) is playing a major role in such deregulated markets. When they are installed in small amounts and small sizes, their impacts on the system may be negligible. When their penetration levels increase as well as their sizes, however, they may start affecting the system performance from more than one aspect. Power system protection needs to be re-assessed after the emergence of DG. This thesis attempts to illustrate the impact of DG on the power system protection coordination. It will study the operation of the impedance relays, fuses, reclosers and overcurrent relays when a DG is added to the distribution network. Different DG sizes, distances from the network and locations within the distribution system will be considered. Power system protection coordination is very sensitive to the DG size where it is not for the DG distance. DG location has direct impact on the operation of the protective devices especially when it is inserted in the middle point of the distribution system. Key Words, Distributed Generation, Impedance relay, fuses, reclosers, overcurrent relays, power system protection coordination.

  12. Robustness analysis of elementary flux modes generated by column generation.

    PubMed

    Oddsdóttir, Hildur Æsa; Hagrot, Erika; Chotteau, Véronique; Forsgren, Anders

    2016-03-01

    Elementary flux modes (EFMs) are vectors defined from a metabolic reaction network, giving the connections between substrates and products. EFMs-based metabolic flux analysis (MFA) estimates the flux over each EFM from external flux measurements through least-squares data fitting. The measurements used in the data fitting are subject to errors. A robust optimization problem includes information on errors and gives a way to examine the sensitivity of the solution of the EFMs-based MFA to these errors. In general, formulating a robust optimization problem may make the problem significantly harder. We show that in the case of the EFMs-based MFA, when the errors are only in measurements and bounded by an interval, the robust problem can be stated as a convex quadratic programming (QP) problem. We have previously shown how the data fitting problem may be solved in a column-generation framework. In this paper, we show how column generation may be applied also to the robust problem, thereby avoiding explicit enumeration of EFMs. Furthermore, the option to indicate intervals on metabolites that are not measured is introduced in this column generation framework. The robustness of the data is evaluated in a case-study, which indicates that the solutions of our non-robust problems are in fact near-optimal also when robustness is considered, implying that the errors in measurement do not have a large impact on the optimal solution. Furthermore, we showed that the addition of intervals on unmeasured metabolites resulted in a change in the optimal solution.

  13. Energy of auroral electrons and Z mode generation

    NASA Technical Reports Server (NTRS)

    Krauss-Varban, D.; Wong, H. K.

    1990-01-01

    The present consideration of Z-mode radiation generation, in light of observational results indicating that the O mode and second-harmonic X-mode emissions can prevail over the X-mode fundamental radiation when suprathermal electron energy is low, gives attention to whether the thermal effect on the Z-mode dispersion can be equally important, and whether the Z-mode can compete for the available free-energy source. It is found that, under suitable circumstances, the growth rate of the Z-mode can be substantial even for low suprathermal auroral electron energies. Growth is generally maximized for propagation perpendicular to the magnetic field.

  14. Diversity of coordination modes in the polymers based on 3,3',4,4'-biphenylcarboxylate ligand

    SciTech Connect

    Du Xiaodi; Xiao Hongping; Zhou Xinhui; Wu Tao; You Xiaozeng

    2010-06-15

    Four new compounds [Ni{sub 2}(4,4'-bpy)(3,4-bptc)(H{sub 2}O){sub 4}]{sub n} (1), [Ni(4,4'-bpy)(3,4-H{sub 2}bptc)(H{sub 2}O){sub 3}]{sub n} (2), [Mn{sub 2}(2,2'-bpy){sub 4}(3,4-H{sub 2}bptc){sub 2}] (3) and {l_brace}[Mn(1,10-phen){sub 2}(3,4-H{sub 2}bptc)].4H{sub 2}O{r_brace}{sub n} (4) (3,4-H{sub 4}bptc=3,3',4,4'-biphenyltetracarboxylic acid, 4,4'-bpy=4,4'-bipyridine, 2,2'-bpy=2,2'-bipyridine, 1, 10-phen=1, 10-phenanthroline), have been prepared and structurally characterized. In all compounds, the derivative ligands of 3,4-H{sub 4}bptc (3,4-bptc{sup 4-} and 3,4-H{sub 2}bptc{sup 2-}) exhibit different coordination modes and lead to the formation of various architectures. Compounds 1 and 2 display the three-dimensional (3D) framework: 1 shows a 3,4-connected topological network with (8{sup 3})(8{sup 5}.10) topology symbol based on the coordination bonds while in 2, the hydrogen-bonding interactions are observed to connect the 1D linear chain generating a final 3D framework. 3 exhibits the 2D layer constructed from the hydrogen-bonding interactions between the dinuclear manganese units. Complex 4 shows the double layers motif through connecting the 1D zigzag chains with hydrogen-bonded rings. The thermal stability of 1-4 and magnetic property of 1 were also reported. - Graphical abstract: Four coordination compounds exhibiting four coordination modes of the 3,3',4,4'-biphenylcarboxylate ligand, with three of new in this system, are obtained showing diversified architectures.

  15. Rigorous study of supercontinuum generation in few mode fibers.

    PubMed

    Salem, Amine Ben; Trichili, Abderrahmen; Cherif, Rim; Zghal, Mourad

    2016-06-01

    We numerically studied supercontinuum (SC) generation in a few-mode photonic crystal fiber (PCF). We have shown the impact of the intermodal nonlinear effects that could limit the fundamental mode nonlinear propagation due to the coupling induced by high-order optical modes. We have demonstrated an accurate modeling of the SC generation into the multimode PCF by solving the multimode generalized nonlinear Shrödinger equation (MM-GNLSE). Our detailed investigation of the dynamics of the intermodal nonlinear effects on the SC process confirms the energy transfer between optical degenerate modes during propagation inside the few-mode PCF.

  16. Two-body coordinate system generation using body-fitted coordinate system and complex variable transformation. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Long, W. S.

    1977-01-01

    Attempts are made to generate acceptable coordinate systems for two-body configurations. The first method to be tried was to use the body-fitted coordinate system technique to obtain the best system. This technique alone did not produce very good results, so another approach was investigated. This new approach involved using a combination of the body fitted coordinate system procedure and a complex variable transformation method that was used successfully in conformal mapping.

  17. Documentation of program AFTBDY to generate coordinate system for 3D after body using body fitted curvilinear coordinates, part 1

    NASA Technical Reports Server (NTRS)

    Kumar, D.

    1980-01-01

    The computer program AFTBDY generates a body fitted curvilinear coordinate system for a wedge curved after body. This wedge curved after body is being used in an experimental program. The coordinate system generated by AFTBDY is used to solve 3D compressible N.S. equations. The coordinate system in the physical plane is a cartesian x,y,z system, whereas, in the transformed plane a rectangular xi, eta, zeta system is used. The coordinate system generated is such that in the transformed plane coordinate spacing in the xi, eta, zeta direction is constant and equal to unity. The physical plane coordinate lines in the different regions are clustered heavily or sparsely depending on the regions where physical quantities to be solved for by the N.S. equations have high or low gradients. The coordinate distribution in the physical plane is such that x stays constant in eta and zeta direction, whereas, z stays constant in xi and eta direction. The desired distribution in x and z is input to the program. Consequently, only the y-coordinate is solved for by the program AFTBDY.

  18. A pentanuclear lead(II) complex based on a strapped porphyrin with three different coordination modes.

    PubMed

    Le Gac, Stéphane; Furet, Eric; Roisnel, Thierry; Hijazi, Ismail; Halet, Jean-François; Boitrel, Bernard

    2014-10-06

    We have previously described Pb(II) and Bi(III) bimetallic complexes with overhanging carboxylic acid strapped porphyrins in which one metal ion is bound to the N-core ("out-of-plane", OOP), whereas the second one is bound to the strap ("hanging-atop", HAT). In such complexes, the hemidirected coordination sphere of a HAT Pb(II) cation provides sufficient space for an additional binding of a neutral ligand (e.g., DMSO). Interestingly, investigations of the HAT metal coordination mode in a single strap porphyrin show that a HAT Pb(II) can also interact via intermolecular coordination bonds, allowing the self-assembly of two bimetallic complexes. In the pentanuclear Pb(II) complex we are describing in this Article, three different coordination modes were found. The OOP Pb(II) remains inert toward the supramolecular assembling process, whereas the HAT Pb(II) cation, in addition to its intramolecular carboxylate and regular exogenous acetate groups, coordinates an additional exogenous acetate. These two acetates are shared with a third lead(II) cation featuring a holo-directed coordination sphere, from which a centro-symmetric complex is assembled. Density functional theory calculations show some electron-density pockets in the vicinity of the hemidirected HAT Pb(II) atoms, which are associated with the presence of a stereochemically active lone pair of electrons. On the basis of the comparison with other HAT Pb(II) and Bi(III) systems, the "volume" of this lone pair correlates well with the bond distance distributions and the number of the proximal oxygen atoms tethered to the post-transition metal cation. It thus follows the order 6-coordinate Bi(III) > 6-coordinate Pb(II) > 5-coordinate Pb(II).

  19. Batch mode grid generation: An endangered species

    NASA Technical Reports Server (NTRS)

    Schuster, David M.

    1992-01-01

    Non-interactive grid generation schemes should thrive as emphasis shifts from development of numerical analysis and design methods to application of these tools to real engineering problems. A strong case is presented for the continued development and application of non-interactive geometry modeling methods. Guidelines, strategies, and techniques for developing and implementing these tools are presented using current non-interactive grid generation methods as examples. These schemes play an important role in the development of multidisciplinary analysis methods and some of these applications are also discussed.

  20. Different coordination modes of 2-(diphenylphosphino)azobenzenes in complexation with hard and soft metals.

    PubMed

    Kano, Naokazu; Yamamura, Masaki; Meng, Xiangtai; Yasuzuka, Takaharu; Kawashima, Takayuki

    2012-10-07

    Control of coordination modes of a ligand in metal complexes is significant because the coordination modes influence catalytic properties of transition metal catalysts. Reactions of 2-diphenylphosphinoazobenzenes, which are in equilibrium with the inner phosphonium salts, with ZnCl(2), W(CO)(5)(THF), and PtCl(2)(cod) gave three different coordination types of metal complexes with distinctive UV-vis absorptions. All the complexes were characterized by X-ray crystallographic analyses. In the zinc and tungsten complexes, the source molecule functions as an amide ligand and a phosphine ligand, respectively. In the platinum complex, the phosphorus molecule works as a tridentate ligand with formation of a carbon-platinum bond.

  1. Mode transition coordinated control for a compound power-split hybrid car

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Zhao, Zhiguo; Zhang, Tong; Li, Mengna

    2017-03-01

    With a compound power-split transmission directly connected to the engine in hybrid cars, dramatic fluctuations in engine output torque result in noticeable jerks when the car is in mode transition from electric drive mode to hybrid drive mode. This study designed a mode transition coordinated control strategy, and verified that strategy's effectiveness with both simulations and experiments. Firstly, the mode transition process was analyzed, and ride comfort issues during the mode transition process were demonstrated. Secondly, engine ripple torque was modeled using the measured cylinder pumping pressure when the engine was not in operation. The complete dynamic plant model of the power-split hybrid car was deduced, and its effectiveness was validated by a comparison of experimental and simulation results. Thirdly, a coordinated control strategy was designed to determine the desired engine torque, motor torque, and the moment of fuel injection. Active damping control with two degrees of freedom, based on reference output shaft speed estimation, was designed to mitigate driveline speed oscillations. Carrier torque estimation based on transmission kinematics and dynamics was used to suppress torque disturbance during engine cranking. The simulation and experimental results indicate that the proposed strategy effectively suppressed vehicle jerks and improved ride comfort during mode transition.

  2. Highly accurate spatial mode generation using spatial cross modulation method for mode division multiplexing

    NASA Astrophysics Data System (ADS)

    Sakuma, Hiroki; Okamoto, Atsushi; Shibukawa, Atsushi; Goto, Yuta; Tomita, Akihisa

    2016-02-01

    We propose a spatial mode generation technology using spatial cross modulation (SCM) for mode division multiplexing (MDM). The most well-known method for generating arbitrary complex amplitude fields is to display an off-axis computer-generated hologram (CGH) on a spatial light modulator (SLM). However, in this method, a desired complex amplitude field is obtained with first order diffraction light. This critically lowers the light utilization efficiency. On the other hand, in the SCM, the desired complex field is provided with zeroth order diffraction light. For this reason, our technology can generate spatial modes with large light utilization efficiency in addition to high accuracy. In this study, first, a numerical simulation was performed to verify that the SCM is applicable for spatial mode generation. Next, we made a comparison from two view points of the coupling efficiency and the light utilization between our technology and the technology using an off-axis amplitude hologram as a representative complex amplitude generation method. The simulation results showed that our technology can achieve considerably high light utilization efficiency while maintaining the enough coupling efficiency comparable to the technology using an off-axis amplitude hologram. Finally, we performed an experiment on spatial modes generation using the SCM. Experimental results showed that our technology has the great potential to realize the spatial mode generation with high accuracy.

  3. Novel vortex generator and mode converter for electron beams.

    PubMed

    Schattschneider, P; Stöger-Pollach, M; Verbeeck, J

    2012-08-24

    A mode converter for electron vortex beams is described. Numerical simulations, confirmed by experiment, show that the converter transforms a vortex beam with a topological charge m=±1 into beams closely resembling Hermite-Gaussian HG(10) and HG(01) modes. The converter can be used as a mode discriminator or filter for electron vortex beams. Combining the converter with a phase plate turns a plane wave into modes with topological charge m=±1. This combination serves as a generator of electron vortex beams of high brilliance.

  4. Distributed Coordination for Optimal Energy Generation and Distribution in Cyber-Physical Energy Networks.

    PubMed

    Ahn, Hyo-Sung; Kim, Byeong-Yeon; Lim, Young-Hun; Lee, Byung-Hun; Oh, Kwang-Kyo

    2017-02-23

    This paper proposes three coordination laws for optimal energy generation and distribution in energy network, which is composed of physical flow layer and cyber communication layer. The physical energy flows through the physical layer; but all the energies are coordinated to generate and flow by distributed coordination algorithms on the basis of communication information. First, distributed energy generation and energy distribution laws are proposed in a decoupled manner without considering the interactive characteristics between the energy generation and energy distribution. Second, a joint coordination law to treat the energy generation and energy distribution in a coupled manner taking account of the interactive characteristics is designed. Third, to handle over- or less-energy generation cases, an energy distribution law for networks with batteries is designed. The coordination laws proposed in this paper are fully distributed in the sense that they are decided optimally only using relative information among neighboring nodes. Through numerical simulations, the validity of the proposed distributed coordination laws is illustrated.

  5. Four homochiral coordination polymers contain N-acetyl-L-tyrosine and different N-donor ligand: Influence of metal cations, ancillary ligands and coordination modes

    SciTech Connect

    Li, Meng-Li; Song, Hui-Hua

    2013-10-15

    Using the chiral ligand N-acetyl-L-tyrosine (Hacty) and maintaining identical reaction conditions, Zn(II), Co(II), and Cd(II) salts provided four novel homochiral coordination polymers ([Zn(acty)(bipy){sub 2}(H{sub 2}O){sub 2}]·NO{sub 3}·2H{sub 2}O){sub n}1, ([Co(acty)(bipy){sub 2}(H{sub 2}O){sub 2}]·NO{sub 3}·2H{sub 2}O){sub n}2, ([Cd(acty){sub 2}(bipy)H{sub 2}O]·H{sub 2}O){sub n}3, and ([Cd(acty)(bpe){sub 2}(Ac)]·6H{sub 2}O){sub n}4 (bipy=4,4′-bipyridine; bpe=1,2-di(4-pyridyl)ethane) in the presence of ancillary ligands. Compounds 1 and 2 are isostructural 1D chain structures. The neighboring chains are further linked into a 3D supramolecular structure via π⋯π stacking and hydrogen bond interactions. Compound 3 shows a 2D network and 4 generates 1D infinite chains along the c-axis. Compounds 3 and 4 are further connected into 3D supramolecular network by hydrogen bond interactions. More importantly, coordination in acyl oxygen atoms and ancillary ligands (bpe) as monodentate decorating ligands in 4 are rarely reported. Ancillary ligands and metal cations significantly influence the structure of the complexes. The photoluminescence properties of 1, 3, and 4 were studied at room temperature. Circular dichroism (CD) of the complexes have been investigated. - Graphical abstract: Four new homochiral coordination polymers were prepared and structurally characterized, which investigate the influence of the ancillary ligands and metal ions on the design and synthesis of coordination polymers. Display Omitted - Highlights: • It is rarely reported that the chiral coordination polymers prepared with N-acetyl-L-tyrosine ligands. • The alkalescent acetyl oxygen atom is difficult to participate in coordination but it is happened in the N-acetyl-L-tyrosine ligands. • The ancillary ligands (4,4′-bipy and bpe) are present in an unusual coordination modes, monodentate decorating ligands in 1, 2 and 4. • Structure comparative analyses results indicate that the

  6. Spectrally tailored supercontinuum generation from single-mode-fiber amplifiers

    SciTech Connect

    Hao, Qiang; Guo, Zhengru; Zhang, Qingshan; Liu, Yang; Li, Wenxue; Zeng, Heping

    2014-05-19

    Spectral filtering of an all-normal-dispersion Yb-doped fiber laser was demonstrated effective for broadband supercontinuum generation in the picosecond time region. The picosecond pump pulses were tailored in spectrum with 1 nm band-pass filter installed between two single-mode fiber amplifiers. By tuning the spectral filter around 1028 nm, four-wave mixing was initiated in a photonic crystal fiber spliced with single-mode fiber, as manifested by the simultaneous generation of Stokes wave at 1076 nm and anti-Stokes wave at 984 nm. Four-wave mixing took place in cascade with the influence of stimulated Raman scattering and eventually extended the output spectrum more than 900 nm of 10 dB bandwidth. This technique allows smooth octave supercontinuum generation by using simple single-mode fiber amplifiers rather than complicated multistage large-mode-area fiber amplifiers.

  7. Spectrally tailored supercontinuum generation from single-mode-fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Hao, Qiang; Guo, Zhengru; Liu, Yang; Li, Wenxue; Zhang, Qingshan; Zeng, Heping

    2014-05-01

    Spectral filtering of an all-normal-dispersion Yb-doped fiber laser was demonstrated effective for broadband supercontinuum generation in the picosecond time region. The picosecond pump pulses were tailored in spectrum with 1 nm band-pass filter installed between two single-mode fiber amplifiers. By tuning the spectral filter around 1028 nm, four-wave mixing was initiated in a photonic crystal fiber spliced with single-mode fiber, as manifested by the simultaneous generation of Stokes wave at 1076 nm and anti-Stokes wave at 984 nm. Four-wave mixing took place in cascade with the influence of stimulated Raman scattering and eventually extended the output spectrum more than 900 nm of 10 dB bandwidth. This technique allows smooth octave supercontinuum generation by using simple single-mode fiber amplifiers rather than complicated multistage large-mode-area fiber amplifiers.

  8. Enhancing backbone sampling in Monte Carlo simulations using internal coordinates normal mode analysis.

    PubMed

    Gil, Victor A; Lecina, Daniel; Grebner, Christoph; Guallar, Victor

    2016-10-15

    Normal mode methods are becoming a popular alternative to sample the conformational landscape of proteins. In this study, we describe the implementation of an internal coordinate normal mode analysis method and its application in exploring protein flexibility by using the Monte Carlo method PELE. This new method alternates two different stages, a perturbation of the backbone through the application of torsional normal modes, and a resampling of the side chains. We have evaluated the new approach using two test systems, ubiquitin and c-Src kinase, and the differences to the original ANM method are assessed by comparing both results to reference molecular dynamics simulations. The results suggest that the sampled phase space in the internal coordinate approach is closer to the molecular dynamics phase space than the one coming from a Cartesian coordinate anisotropic network model. In addition, the new method shows a great speedup (∼5-7×), making it a good candidate for future normal mode implementations in Monte Carlo methods.

  9. Identifying electron transfer coordinates in donor-bridge-acceptor systems using mode projection analysis

    PubMed Central

    Yang, Xunmo; Keane, Theo; Delor, Milan; Meijer, Anthony J. H. M.; Weinstein, Julia; Bittner, Eric R.

    2017-01-01

    We report upon an analysis of the vibrational modes that couple and drive the state-to-state electronic transfer branching ratios in a model donor-bridge-acceptor system consisting of a phenothiazine-based donor linked to a naphthalene-monoimide acceptor via a platinum-acetylide bridging unit. Our analysis is based upon an iterative Lanczos search algorithm that finds superpositions of vibronic modes that optimize the electron/nuclear coupling using input from excited-state quantum chemical methods. Our results indicate that the electron transfer reaction coordinates between a triplet charge-transfer state and lower lying charge-separated and localized excitonic states are dominated by asymmetric and symmetric modes of the acetylene groups on either side of the central atom in this system. In particular, we find that while a nearly symmetric mode couples both the charge-separation and charge-recombination transitions more or less equally, the coupling along an asymmetric mode is far greater suggesting that IR excitation of the acetylene modes preferentially enhances charge-recombination transition relative to charge-separation. PMID:28233775

  10. Microwave filter based on Lamb modes for optoelectronic generator

    NASA Astrophysics Data System (ADS)

    Vitko, V. V.; Nikitin, A. A.; Kondrashov, A. V.; Nikitin, A. A.; Ustinov, A. B.; Belyavskiy, P. Yu; Kalinikos, B. A.; Butler, J. E.

    2015-12-01

    Experimental results for narrowband filter based on yttrium iron garnet film epitaxially grown on gadolinium gallium garnet substrate have been shown. The principle of operation of the filter is based on excitation of Lamb modes in the substrate. We demonstrated also that the use of single crystal diamond as a substrate will significantly reduce the phase noise of the designed optoelectronic microwave generator.

  11. Pi-metal complexes of tetrapyrrolic systems. A novel coordination mode in "porphyrin-like" chemistry.

    PubMed

    Cuesta, Luciano; Sessler, Jonathan L

    2009-09-01

    The coordination chemistry of porphyrins and related tetrapyrrolic ligands has traditionally centered around the ability of these systems to form pyrrole N-ligated complexes via the formation of sigma bonds, either within the N(4) core or displaced above it. In fact, such sigma-complexes are known with almost every metal cation in the periodic table. However, a growing number of pi-complexes derived from tetrapyrrolic ligands have been reported in recent years. The underlying coordination mode, while still novel in the context of "porphyrin-like" chemistry, is already being recognized for the effects it can impart over the reactivity, as well as the spectroscopic, redox, electronic, and optical properties of various oligopyrrolic macrocycles. This critical review summarizes accomplishments made in this fast-emerging field (59 references).

  12. Mean flow generation mechanism by inertial waves and normal modes

    NASA Astrophysics Data System (ADS)

    Will, Andreas; Ghasemi, Abouzar

    2016-04-01

    The mean flow generation mechanism by nonlinearity of the inertial normal modes and inertial wave beams in a rotating annular cavity with longitudinally librating walls in stable regime is discussed. Inertial normal modes (standing waves) are excited when libration frequency matches eigenfrequencies of the system. Inertial wave beams are produced by Ekman pumping and suction in a rotating cylinder and form periodic orbits or periodic ray trajectories at selected frequencies. Inertial wave beams emerge as concentrated shear layers in a librating annular cavity, while normal modes appear as global recirculation cells. Both (inertial wave beam and mode) are helical and thus intrinsically non-linear flow structures. No second mode or wave is necessary for non-linearity. We considered the low order normal modes (1,1), (2,1) and (2,2) which are expected to be excited in the planetary objects and investigate the mean flow generation mechanism using two independent solutions: 1) analytical solution (Borcia 2012) and 2) the wave component of the flow (ω0 component) obtained from the direct numerical simulation (DNS). It is well known that a retrograde bulk mean flow is generated by the Ekman boundary layer and E1/4-Stewartson layer close to the outer cylinder side wall due to libration. At and around the normal mode resonant frequencies we found additionally a prograde azimuthal mean flow (Inertial Normal Mode Mean Flow: INMMF) in the bulk of the fluid. The fluid in the bulk is in geostrophic balance in the absence of the inertial normal modes. However, when INMMF is excited, we found that the geostrophic balance does not hold in the region occupied by INMMF. We hypothesize that INMMF is generated by the nonlinearity of the normal modes or by second order effects. Expanding the velocity {V}(u_r,u_θ,u_z) and pressure (p) in a power series in ɛ (libration amplitude), the Navier-Stokes equations are segregated into the linear and nonlinear parts at orders ɛ1 and ɛ^2

  13. Edge Plasma Boundary Layer Generated By Kink Modes in Tokamaks

    SciTech Connect

    L.E. Zakharov

    2010-11-22

    This paper describes the structure of the electric current generated by external kink modes at the plasma edge using the ideally conducting plasma model. It is found that the edge current layer is created by both wall touching and free boundary kink modes. Near marginal stability, the total edge current has a universal expression as a result of partial compensation of the δ-functional surface current by the bulk current at the edge. The resolution of an apparent paradox with the pressure balance across the plasma boundary in the presence of the surface currents is provided.

  14. Second-harmonic generation in single-mode integrated waveguides based on mode-shape modulation

    NASA Astrophysics Data System (ADS)

    Rao, Ashutosh; Chiles, Jeff; Khan, Saeed; Toroghi, Seyfollah; Malinowski, Marcin; Camacho-González, Guillermo Fernando; Fathpour, Sasan

    2017-03-01

    Second-harmonic generation is demonstrated using grating-assisted quasi-phase matching, based on waveguide-width modulation or mode-shape modulation. Applicable to any thin-film integrated second-order nonlinear waveguide, the technique is demonstrated in compact lithium niobate ridge waveguides. Fabricated devices are characterized with pulsed-pumping in the near-infrared, showing second-harmonic generation at a signal wavelength of 784 nm and propagation loss of 1 dB/cm.

  15. New water soluble heterometallic complex showing unpredicted coordination modes of EDTA

    SciTech Connect

    Mudsainiyan, R.K. Jassal, A.K.; Chawla, S.K.

    2015-10-15

    A mesoporous 3D polymeric complex (I) having formula ([Zr(IV)O-μ{sup 3}-(EDTA)Fe(III)OH]·H{sub 2}O){sub n} has been crystallized and characterized by various techniques. Single-crystal X-ray diffraction analysis revealed that complex (I) crystallized in chiral monoclinic space group Cc (space group no. 9) with unexpected coordination modes of EDTA and mixture of two transition metal ions. In this complex, the coordination number of Zr(IV) ion is seven where four carboxylate oxygen atoms, two nitrogen atoms, one oxide atom are coordinating with Zr(IV). Fe(III) is four coordinated and its coordination environment is composed of three different carboxylic oxygen atoms from three different EDTA and one oxygen atom of –OH group. The structure consists of 4-c and 16-c (2-nodal) net with new topology and point symbol for net is (3{sup 36}·4{sup 54}·5{sup 30})·(3{sup 6}). TGA study and XRPD pattern showed that the coordination polymer is quite stable even after losing water molecule and –OH ion. Quenching behavior in fluorescence of ligand is observed by complexation with transition metal ions is due to n–π⁎ transition. The SEM micrograph shows the morphology of complex (I) exhibits spherical shape with size ranging from 50 to 280 nm. The minimum N{sub 2} (S{sub BET}=8.7693 m{sup 2}/g) and a maximum amount of H{sub 2} (high surface area=1044.86 m{sup 2}/g (STP)) could be adsorbed at 77 K. From DLS study, zeta potential is calculated i.e. −7.94 shows the negative charges on the surface of complex. Hirshfeld surface analysis and fingerprint plots revealed influence of weak or non bonding interactions in crystal packing of complex. - Graphical abstract: The complex (I) crystallized with unexpected coordination modes of EDTA having 4-c, 16-c net with new topology and point symbol is (3{sup 36}·4{sup 54}·5{sup 30})·(3{sup 6}). TGA study and XRPD pattern proved its stability with high preference of H{sub 2} uptake by complex. - Highlights: • 3D complex

  16. Generation of Higher Order Modes in a Rectangular Duct

    NASA Technical Reports Server (NTRS)

    Gerhold, Carl H.; Cabell, Randolph H.; Brown, Donald E.

    2004-01-01

    Advanced noise control methodologies to reduce sound emission from aircraft engines take advantage of the modal structure of the noise in the duct. This noise is caused by the interaction of rotor wakes with downstream obstructions such as exit guide vanes. Mode synthesis has been accomplished in circular ducts and current active noise control work has made use of this capability to cancel fan noise. The goal of the current effort is to examine the fundamental process of higher order mode propagation through an acoustically treated, curved duct. The duct cross-section is rectangular to permit greater flexibility in representation of a range of duct curvatures. The work presented is the development of a feedforward control system to generate a user-specified modal pattern in the duct. The multiple-error, filtered-x LMS algorithm is used to determine the magnitude and phase of signal input to the loudspeakers to produce a desired modal pattern at a set of error microphones. Implementation issues, including loudspeaker placement and error microphone placement, are discussed. Preliminary results from a 9-3/8 inch by 21 inch duct, using 12 loudspeakers and 24 microphones, are presented. These results demonstrate the ability of the control system to generate a user-specified mode while suppressing undesired modes.

  17. A coordinated MIMO control design for a power plant using improved sliding mode controller.

    PubMed

    Ataei, Mohammad; Hooshmand, Rahmat-Allah; Samani, Siavash Golmohammadi

    2014-03-01

    For the participation of the steam power plants in regulating the network frequency, boilers and turbines should be co-ordinately controlled in addition to the base load productions. Lack of coordinated control over boiler-turbine may lead to instability; oscillation in producing power and boiler parameters; reduction in the reliability of the unit; and inflicting thermodynamic tension on devices. This paper proposes a boiler-turbine coordinated multivariable control system based on improved sliding mode controller (ISMC). The system controls two main boiler-turbine parameters i.e., the turbine revolution and superheated steam pressure of the boiler output. For this purpose, a comprehensive model of the system including complete and exact description of the subsystems is extracted. The parameters of this model are determined according to our case study that is the 320MW unit of Islam-Abad power plant in Isfahan/Iran. The ISMC method is simulated on the power plant and its performance is compared with the related real PI (proportional-integral) controllers which have been used in this unit. The simulation results show the capability of the proposed controller system in controlling local network frequency and superheated steam pressure in the presence of load variations and disturbances of boiler.

  18. Multi-Index Nonlinear Coordinated Control for Battery Energy Storage System and Generator Excitation

    NASA Astrophysics Data System (ADS)

    Lingyi, Kong; Liying, Liao

    A multi-index nonlinear coordinated control scheme for BESS and generator excitation is proposed. The proposed multi-index nonlinear coordinated controller can effectively coordinate the dynamic and steady-state performance of the controlled system. It can enhance the stability of the system, improve the dynamic characteristics of state variables, and can improve the control accuracy of output variables such as terminal voltage, active power output of the generator. Simulation results show that to control BESS and generator coordinately has the advantage of enhancing the stability of the system. With the ability of BESS to control the active power and reactive power, and the regulate of generator excitation, the dynamic characteristics of state variables can changes more smoothness, responds more speediness.

  19. Generator coordinate method and nuclear collective motions (VII): the preservation of symmetry properties

    SciTech Connect

    XU Gong-ou

    1985-01-01

    In order to preserve all the symmetry properties for the effective collective Hamiltonian obtained with the generator coordinate method, it is necessary for the trial wave function to have proper transformation properties. The generator coordinates should then transform in the same way as the represented collective operators. Also, the center-of-mass motion should be independent of the internal motion in conformity with the invariance of the nuclear Hamiltonian with respect to space rotation and Galilean transformation.

  20. A new description of Earth's wobble modes using Clairaut coordinates 2: results and inferences on the core mode spectrum

    NASA Astrophysics Data System (ADS)

    Crossley, D. J.; Rochester, M. G.

    2014-09-01

    Numerical solutions are presented for the formulation of the linear momentum description of Earth's dynamics using Clairaut coordinates. We have developed a number of methods to integrate the equations of motion, including starting at the Earth's centre of mass, starting at finite radius and separating the displacement associated with the primary rigid rotation. We include rotation and ellipticity to second order up to spherical harmonic T_5^m, starting with the primary displacement T_1^m with m = ±1. We are able to confirm many of the previous results for models PREM (with no surface ocean) and 1066A, both in their original form and with neutrally stratified liquid cores. Our period search ranges from the near-seismic band [0.1 sidereal days (sd)] to 3500 sd, within which we have identified the four well-known wobble-nutation modes: the Free Core Nutation (retrograde) at -456 sd, the Free Inner Core Nutation (FICN, prograde) at 468 sd, the Chandler Wobble (prograde) at 402 sd, and the Inner Core Wobble (ICW, prograde) at about 2842 sd (7.8 yr) for neutral PREM. The latter value varies significantly with earth model and integration method. In addition we have verified to high accuracy the tilt-over mode at 1 sd within a factor 10-6. In an exhaustive search we found no additional near-diurnal wobble modes that could be identified as nutations. We show that the eigenfunctions for the as-yet-unidentified ICW are extremely sensitive to the details of the earth model, especially the core stability profile and there is no well-defined sense of its wobble relative to the mantle. Calculations are also done for a range of models derived from PREM with homogeneous layers, as well as with incompressible cores. For this kind of model the ICW ceases to have just a simple IC rigid motion when the fluid compressibility is either unchanged or multiplied by a factor 10; in this case the outer core exhibits oscillations that arise from an unstable fluid density stratification. For

  1. Corrugated waveguide mode purifier for TEM output in a dual-mode operation overmoded coaxial millimeter-wave generator

    NASA Astrophysics Data System (ADS)

    Bai, Zhen; Zhang, Jun; Zhong, Huihuang; Zhang, Dian

    2017-01-01

    A coaxial corrugated waveguide mode purifier is designed for a dual-mode operation overmoded coaxial millimeter-wave generator. With the purifier, the mixed TEM and TM01 modes output are purified into a pure TEM mode. Particle-in-cell (PIC) simulation shows that the purifier would not decrease the total output power of the generator, and plays an independent role to the upstream structure. Effects of mode composition ratio and phase difference on the purification ability of the purifier are also researched by both electromagnetism and PIC simulations, which show that the purifier has a certain tolerance for both the mode composition ratio and phase difference.

  2. Sliding mode coordination control for multiagent systems with underactuated agent dynamics

    NASA Astrophysics Data System (ADS)

    Ghasemi, Masood; Nersesov, Sergey G.; Clayton, Garrett; Ashrafiuon, Hashem

    2014-12-01

    In this paper, we develop a new integrated coordinated control and obstacle avoidance approach for a general class of underactuated agents. We use graph-theoretic notions to characterise communication topology in the network of underactuated agents as determined by the information flow directions and captured by the graph Laplacian matrix. Obstacle avoidance is achieved by surrounding the stationary as well as moving obstacles by elliptical or other convex shapes that serve as stable periodic solutions to planar systems of ordinary differential equations and using transient trajectories of those systems to navigate the agents around the obstacles. Decentralised controllers for individual agents are designed using sliding mode control approach and are only based on data communicated from the neighbouring agents. We demonstrate the efficacy of our theoretical approach using an example of a system of wheeled mobile robots that reach and maintain a desired formation. Finally, we validate our results experimentally.

  3. Thermodynamic, spectroscopic, and computational studies of lanthanide complexation with Diethylenetriaminepentaacetic acide: temperature effect and coordination modes

    SciTech Connect

    Guoxin Tian; Leigh R. Martin; Zhiyong Zhang; Linfeng Rao

    2011-04-01

    Stability constants of two DTPA (diethylenetriaminepentaacetic acid) complexes with lanthanides (ML2- and MHL-, where M stands for Nd and Eu and L stands for diethylenetriaminepentaacetate) at 10, 25, 40, 55, and 70 degrees C were determined by potentiometry, absorption spectrophotometry, and luminescence spectroscopy. The enthalpies of complexation at 25 degrees C were determined by microcalorimetry. Thermodynamic data show that the complexation of Nd3þ and Eu3þ with DTPA is weakened at higher temperatures, a 10-fold decrease in the stability constants of ML2- and MHL- as the temperature is increased from 10 to 70 degrees C. The effect of temperature is consistent with the exothermic enthalpy of complexation directly measured by microcalorimetry. Results by luminescence spectroscopy and density functional theory (DFT) calculations suggest that DTPA is octa-dentate in both the EuL2- and EuHL- complexes and, for the first time, the coordination mode in the EuHL- complex was clarified by integration of the experimental data and DFT calculations. In the EuHL- complex, the Eu is coordinated by an octa-dentate H(DTPA) ligand and a water molecule, and the protonation occurs on the oxygen of a carboxylate group.

  4. Retinal determination genes coordinate neuroepithelial specification and neurogenesis modes in the Drosophila optic lobe

    PubMed Central

    Apitz, Holger

    2016-01-01

    Differences in neuroepithelial patterning and neurogenesis modes contribute to area-specific diversifications of neural circuits. In the Drosophila visual system, two neuroepithelia, the outer (OPC) and inner (IPC) proliferation centers, generate neuron subtypes for four ganglia in several ways. Whereas neuroepithelial cells in the medial OPC directly convert into neuroblasts, in an IPC subdomain they generate migratory progenitors by epithelial-mesenchymal transition that mature into neuroblasts in a second proliferative zone. The molecular mechanisms that regulate the identity of these neuroepithelia, including their neurogenesis modes, remain poorly understood. Analysis of Polycomblike revealed that loss of Polycomb group-mediated repression of the Hox gene Abdominal-B (Abd-B) caused the transformation of OPC to IPC neuroepithelial identity. This suggests that the neuroepithelial default state is IPC-like, whereas OPC identity is derived. Ectopic Abd-B blocks expression of the highly conserved retinal determination gene network members Eyes absent (Eya), Sine oculis (So) and Homothorax (Hth). These factors are essential for OPC specification and neurogenesis control. Finally, eya and so are also sufficient to confer OPC-like identity, and, in parallel with hth, the OPC-specific neurogenesis mode on the IPC. PMID:27381228

  5. Revisiting Modes of energy generation in sulfate reducing bacteria

    SciTech Connect

    Joachimiak, Marcin; Chakraborty, Romy; Zhou, Aifen; Fortney, Julian; Geller, Jil; Wall, Judy; Zhou, Jizhong; Arkin, Adam; Hazen, Terry; Keasling, Jay; Chhabra, Swapnil

    2010-05-17

    Sulfate reducing bacteria (SRB) play an important role in global sulfur and carbon cycling through their ability to completely mineralize organic matter while respiring sulfate to hydrogen sulfide. They are ubiquitous in anaerobic environments and have the ability to reduce toxic metals like Cr(VI) and U(VI). While SRB have been studied for over three decades, bioenergetic modes of this group of microbes are poorly understood. Desulfovibrio vulgaris strain Hildenborough (DvH) has served as a model SRB over the last decade with the accumulation of transcriptomic, proteomic and metabolic data under a wide variety of stressors. To further investigate the three hypothesized modes of energy generation in this anaerobe we conducted a systematic study involving multiple electron donor and acceptor combinations for growth. DvH was grown at 37oC in a defined medium with (a) lactate + thiosulfate, (b) lactate + sulfite (c) lactate + sulfate, (d) pyruvate + sulfate, (e) H2 + acetate + sulfate, (f) formate + acetate + sulfate, g) formate + sulfate and (h) pyruvate fermentation. Cells were harvested at mid-log phase of growth for all conditions for transcriptomics, when the optical density at 600nm was in the range 0.42-0.5. Initial results indicate that cells grown on lactate do not appear to significantly differentiate their gene expression profiles when presented with different electron acceptors. These profiles however differ significantly from those observed during growth with other electron donors such as H2 and formate, as well as during fermentative growth. Together the gene expression changes in the presence of different electron donors provide insights into the ability of DvH to differentially reduce metals such as Cr(VI). Here we present revised modes of energy generation in DvH in light of this new transcriptomic evidence.

  6. Tensors and Differential Geometry Applied to Analytic and Numerical Coordinate Generation

    DTIC Science & Technology

    1981-01-01

    C., Space Through the Ages, Academic Press, New York (1970). [291 Thompson , J . F ., Thames, F. C., and Mastin, C. W., "Automatic Numerical Generation...in 1923). [35] Private communication from J. F. Thompson. [36] Warsi, Z. U. A., and Thompson , J . F ., "Numerical Generation of Two-Dimensional...Z. U. A., and Thompson , J . F ., "Machine Solutions of Partial Differential Equations in the Numerically Generated Coordinate Systems," Engineering

  7. Celiac disease biodetection using lossy-mode resonances generated in tapered single-mode optical fibers

    NASA Astrophysics Data System (ADS)

    Socorro, A. B.; Corres, J. M.; Del Villar, I.; Matias, I. R.; Arregui, F. J.

    2014-05-01

    This work presents the development and test of an anti-gliadin antibodies biosensor based on lossy mode resonances (LMRs) to detect celiac disease. Several polyelectrolites were used to perform layer-by-layer assembly processes in order to generate the LMR and to fabricate a gliadin-embedded thin-film. The LMR shifted 20 nm when immersed in a 5 ppm anti-gliadin antibodies-PBS solution, what makes this bioprobe suitable for detecting celiac disease. This is the first time, to our knowledge, that LMRs are used to detect celiac disease and these results suppose promising prospects on the use of such phenomena as biological detectors.

  8. Generation mechanism of whistler-mode chorus emissions

    NASA Astrophysics Data System (ADS)

    Omura, Yoshiharu

    We describe the nonlinear dynamics of resonant electrons interacting with a coherent whistler-mode wave and the formation of electromagnetic electron holes or hills in the velocity phase space. In the presence of the inhomogeneity due to the frequency variation and the gradient of the magnetic field, the electron holes or hills result in resonant currents generating rising-tone emissions (1, 2) or falling-tone emissions (3), respectively. After formation of a coherent wave at the maximum linear growth rate, triggering of the nonlinear wave growth takes place when the wave amplitude is close to the optimum wave amplitude (4). The wave amplitude also has to be above the threshold amplitude (2) so that the nonlinear wave growth can occur as an absolute instability at the magnetic equator. The triggering process is repeated at progressively higher frequencies in the case of a rising-tone emission, generating subpackets of a chorus element. We also describe the mechanism of nonlinear wave damping due to quasi-oblique propagation from the equator (2), which results in the formation of a gap at half the electron cyclotron frequency, separating a long rising-tone chorus emission into the upper-band and lower-band chorus emissions (5). *References (1) Y. Omura,Y. Katoh, and D. Summers, Theory and simulation of the generation of whistler-mode chorus, J. Geophys. Res., 113, A04223, 2008. (2) Y. Omura, , M. Hikishima, Y. Katoh, D. Summers, and S. Yagitani, Nonlinear mechanisms of lower band and upper band VLF chorus emissions in the magnetosphere, J. Geophys. Res., 114, A07217, 2009. (3) Nunn, D., and Y. Omura, A computational and theoretical analysis of falling frequency VLF emissions, J. Geophys. Res., 117, A08228, 2012. (4) Omura, Y., and D. Nunn, Triggering process of whistler mode chorus emissions in the magnetosphere, J. Geophys. Res., 116, A05205, 2011. (5) S. Kurita, Y. Katoh, Y. Omura, V. Angelopoulos, C. M. Cully, O. Le Contel, and H. Misawa, THEMIS observation of

  9. Dynamic Jahn-Teller viewpoint for generation mechanism of asymmetric modes of coherent phonons

    NASA Astrophysics Data System (ADS)

    Kayanuma, Yosuke; Nakamura, Kazutaka G.

    2017-03-01

    We propose a dynamic Jahn-Teller approach to elucidate the generation mechanism of asymmetric modes of coherent phonons induced in crystals by irradiation with a short optical pulse in the opaque energy region. This is a natural extension of the impulsive excitation model of symmetric modes to multi dimensions in the configuration coordinate space. We show that the two generation mechanisms of coherent phonons coexist in this case, namely the impulsive absorption (IA) mechanism and impulsive stimulated Raman scattering (ISRS) mechanism. The dependence of the phonon amplitude on the polarization of the pump pulse is exactly the same in IA and ISRS processes and is in agreement with the prediction of the argument based on Raman tensors. The dependence of the excitation efficiency of the coherent phonons on the frequency of the pump pulse is calculated using a simplified model of the optical response function of the crystal. Generally, the IA mechanism predominates in the opaque region, although ISRS makes a comparable contribution to phonon generation in the near-edge opaque region. The initial phase of the coherent phonon is always cosine-like in IA but depends on the excitation frequency in ISRS.

  10. Spatial Bell-State Generation without Transverse Mode Subspace Postselection

    NASA Astrophysics Data System (ADS)

    Kovlakov, E. V.; Bobrov, I. B.; Straupe, S. S.; Kulik, S. P.

    2017-01-01

    Spatial states of single photons and spatially entangled photon pairs are becoming an important resource in quantum communication. This additional degree of freedom provides an almost unlimited information capacity, making the development of high-quality sources of spatial entanglement a well-motivated research direction. We report an experimental method for generation of photon pairs in a maximally entangled spatial state. In contrast to existing techniques, the method does not require postselection of a particular subspace of spatial modes and allows one to use the full photon flux from the nonlinear crystal, providing a tool for creating high-brightness sources of pure spatially entangled photons. Such sources are a prerequisite for emerging applications in free-space quantum communication.

  11. A new description of Earth's wobble modes using Clairaut coordinates: 1. Theory

    NASA Astrophysics Data System (ADS)

    Rochester, M. G.; Crossley, D. J.; Zhang, Y. L.

    2014-09-01

    This paper presents a novel mathematical reformulation of the theory of the free wobble/nutation of an axisymmetric reference earth model in hydrostatic equilibrium, using the linear momentum description. The new features of this work consist in the use of (i) Clairaut coordinates (rather than spherical polars), (ii) standard spherical harmonics (rather than generalized spherical surface harmonics), (iii) linear operators (rather than J-square symbols) to represent the effects of rotational and ellipticity coupling between dependent variables of different harmonic degree and (iv) a set of dependent variables all of which are continuous across material boundaries. The resulting infinite system of coupled ordinary differential equations is given explicitly, for an elastic solid mantle and inner core, an inviscid outer core and no magnetic field. The formulation is done to second order in the Earth's ellipticity. To this order it is shown that for wobble modes (in which the lowest harmonic in the displacement field is degree 1 toroidal, with azimuthal order m = ±1), it is sufficient to truncate the chain of coupled displacement fields at the toroidal harmonic of degree 5 in the solid parts of the earth model. In the liquid core, however, the harmonic expansion of displacement can in principle continue to indefinitely high degree at this order of accuracy. The full equations are shown to yield correct results in three simple cases amenable to analytic solution: a general earth model in rigid rotation, the tiltover mode in a homogeneous solid earth model and the tiltover and Chandler periods for an incompressible homogeneous solid earth model. Numerical results, from programmes based on this formulation, are presented in part II of this paper.

  12. A Four-Quadrant Operation Diagram for Thermoelectric Modules in Heating-Cooling Mode and Generating Mode

    NASA Astrophysics Data System (ADS)

    Chimchavee, W.

    2011-05-01

    The operation of a thermoelectric module in heating-cooling mode, generating mode, and regenerating mode can be discussed in terms of power, cooling load, and current. A direct current machine in motoring mode and generating mode and an induction motor in motoring mode and regenerating mode are analogous to thermoelectric modules. Therefore, the first objective of this work is to present the four-quadrant (4-Q) operation diagram and the 4-Q equivalent circuits of thermoelectric modules in heating-cooling mode and generating mode. The second objective is to present the cooling and regenerating curves of a thermoelectric module in cooling mode and regenerating mode. The curves are composed from the cooling powers and the generating powers, the input and output current, the thermal resistance of the heat exchanger, and the different temperatures that exist between the hot and cold sides of the thermoelectric module. The methodology used to present the data involved drawing analogies between the mechanical system, the electrical system, and the thermal system; an experimental setup was also used. The experimental setup was built to test a thermoelectric module (TE2) in cooling mode and regenerating mode under conditions in which it was necessary to control the different temperatures on the hot and cold sides of TE2. Two thermoelectric modules were used to control the temperature. The cold side was controlled by a thermoelectric module labeled TE1, whereas the hot side was controlled by a second thermoelectric module labeled TE3. The results include the power, the cooling load, and the current of the thermoelectric module, which are analogous to the torque, the power, the speed, and the slip speed of a direct current machine and an induction motor. This 4-Q operation diagram, the 4-Q equivalent circuits, and the cooling and regenerating curves of the thermoelectric module can be used to analyze the bidirectional current and to select appropriate operating conditions in

  13. Proper orthogonal decomposition and component mode synthesis in macromodel generation for the dynamic simulation of a complex MEMS device

    NASA Astrophysics Data System (ADS)

    Lin, W. Z.; Lee, K. H.; Lim, S. P.; Liang, Y. C.

    2003-09-01

    In this paper, we develop a novel method for the macromodel generation for the dynamic simulation and analysis of a structurally complex MEMS device, by making use of proper orthogonal decomposition (POD), also known as the Karhunen-Loève decomposition and classical component mode synthesis. The complex microelectromechanical systems (MEMS) device is divided into interconnected components and each of these components is treated separately using POD to extract its proper orthogonal modes (POMs) and their corresponding proper orthogonal values. The separate component responses are then expressed in generalized coordinates that are defined by the POMs. The requirements of the displacement and force compatibility at the interface of components serve as constraint equations among the component coordinates, and are used to construct a transformation relating the component coordinates to system coordinates. This transformation is used to formulate the low-order macromodel to determine system dynamic responses. Numerical results obtained from the simulation of pull-in dynamics of a non-uniform microbeam MEMS device subjected to electrostatic actuation force with squeezed gas-film damping effect show that the macromodel generated this way can dramatically reduce the computation time while capturing the device behaviour faithfully.

  14. Generator coordinate method and nuclear collective motions: VI on the problem of overcompleteness

    SciTech Connect

    Xu Gong-ou

    1984-01-01

    The problem of overcompleteness in the generator coordinate method is generally studied. It is shown that the effective operator (ON/sup -1/) as a whole excludes the coupling between the physical and unphysical states and the problem of overcompleteness is resolved in this sense. This conclusion is illustrated with an example of boson representations of the SU(6) group.

  15. Generation of infrared supercontinuum radiation: spatial mode dispersion and higher-order mode propagation in ZBLAN step-index fibers.

    PubMed

    Ramsay, Jacob; Dupont, Sune; Johansen, Mikkel; Rishøj, Lars; Rottwitt, Karsten; Moselund, Peter Morten; Keiding, Søren Rud

    2013-05-06

    Using femtosecond upconversion we investigate the time and wavelength structure of infrared supercontinuum generation. It is shown that radiation is scattered into higher order spatial modes (HOMs) when generating a supercontinuum using fibers that are not single-moded, such as a step-index ZBLAN fiber. As a consequence of intermodal scattering and the difference in group velocity for the modes, the supercontinuum splits up spatially and temporally. Experimental results indicate that a significant part of the radiation propagates in HOMs. Conventional simulations of super-continuum generation do not include scattering into HOMs, and including this provides an extra degree of freedom for tailoring supercontinuum sources.

  16. Zonal flow generation from trapped electron mode turbulence

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Hahm, T. S.

    2009-11-01

    Most existing zonal flow generation theory [1,2] has been developed with a usual assumption of qrρiθ<<1 (qr is the radial wave number of zonal flow, and ρiθ is the ion poloidal gyroradius). However, recent nonlinear gyrokinetic simulations of trapped electron mode (TEM) turbulence exhibit a relatively short radial scale of the zonal flows with qrρiθ˜1 [3,4,5]. This work reports an extension of zonal flow growth calculation to this short wavelength regime via the wave kinetics approach. A generalized expression for the polarization shielding for arbitrary radial wavelength [6] which extends the Rosenbluth-Hinton formula in the long wavelength limit [7] is applied. The electron nonlinearity effects on zonal flow are investigated by using GTC simulation. This work was supported by the China Scholarship Council (LW), U.S. DoE Contract No. DE--AC02--09CH11466 (TSH, LW), the U. S. DOE SciDAC center for Gyrokinetic Particle Simulation of Turbulent Transport in Burning Plasmas, and the U. S. DOE SciDAC-FSP Center for Plasma Edge Simulation (TSH). [1] P. H. Diamond et al., IAEA-CN-69/TH3/1 (1998). [2] L. Chen, Z. Lin, and R. White, Phys. Plasmas 7, 3129 (2000). [3] Z. Lin et al., IAEA-CN-138/TH/P2-8 (2006). [4] D. Ernst et al., Phys. Plasmas 16, 055906 (2009). [5] Y. Xiao and Z. Lin, ``Turbulent transport of trapped electron modes in collisionless plasmas'', submitted to Phys. Rev. Lett. (2009). [6] Lu Wang and T.S. Hahm, Phys. Plasmas 16, 062309 (2009). [7] M. N. Rosenbluth and F. L. Hinton, Phys. Rev. Lett. 80, 724 (1998).

  17. Synthesis, structural characterization and microbial activity of 2D Ag(I)-5-aminoisophthalate coordination polymer with a new coordination mode

    NASA Astrophysics Data System (ADS)

    Günay, Handan; Çolak, Alper Tolga; Yeşilel, Okan Zafer; Tunç, Tuncay; Çolak, Ferdağ

    2015-11-01

    In this study, a novel polynuclear Ag(I)-5-aminoisophthalate complex [Ag(μ4-Haip)]n (1) (H2aip = 5-aminoisophthalic acid) has been synthesized. The molecular structure of this complex has been determined by the single crystal X-ray diffraction. The two-dimensional polynuclear complex is crystallized in the triclinic crystal system with space group P-1. The Ag(I) ion is four-coordinated by three carboxylate oxygen atoms of three different Haip ligands and one nitrogen atom in a distorted tetrahedral geometry. Furthermore, a novel coordination mode has shown by H2aip. This complex exhibits photoluminescence in the solid state at room temperature. Antimicrobial activity of complex was evaluated by the agar diffusion method. The complex showed antimicrobial activity against tested microorganism strains (Gram positive, gram negative bacteria, clinic isolate yeast and mold). Moreover this complex showed particularly high antifungal activity against yeast and mold.

  18. Function generator for synthesizing complex vibration mode patterns

    NASA Technical Reports Server (NTRS)

    Naumann, E. C.; Hagood, G. J., Jr. (Inventor)

    1973-01-01

    A simple highly flexible device for synthesizing complex vibration mode patterns is described. These mode patterns can be used to identify vibration mode data. This device sums selected sine and cosine functions and then plots the sum against a linear function.

  19. Entanglement generation between two atoms via surface modes

    SciTech Connect

    Xu Jingping; Yang Yaping; Al-Amri, M.; Zhu Shiyao; Zubairy, M. Suhail

    2011-09-15

    We discuss the coupling of two identical atoms, separated by a metal or metamaterial slab, through surface modes. We show that the coupling through the surface modes can induce entanglement. We discuss how to control the coupling for the metal or metamaterial slab by adjusting the symmetrical and antisymmetrical property of the surface modes. We analyze the dispersion relation of the surface modes and study the parameter ranges that support the surface modes with the same properties. Our results have potential applications in quantum communication and quantum computation.

  20. Mechanisms of subantarctic mode water upwelling in a hybrid-coordinate global GCM

    NASA Astrophysics Data System (ADS)

    Zuo, Hao; Naveira Garabato, Alberto C.; New, Adrian L.; Oschlies, Andreas

    This article presents an investigation of the global circulation and upwelling of subantarctic mode water (SAMW), which is thought to be key in the supply of nutrients to support biological production over much of the world ocean excluding the North Pacific. The HYbrid isopycnic-cartesian Coordinate Ocean general circulation Model (HYCOM) is configured to simulate the global ocean circulation for time scales of up to centuries and a SAMW-tracking online tracer experiment is conducted. The tracer re-emergence fluxes across the mixed layer base effected by a range of physical mechanisms and by numerical mixing terms in HYCOM are diagnosed and discussed. For the global ocean north of 30°S, entrainment due to surface buoyancy loss and/or wind-induced mechanical stirring accounts for almost one third of the total tracer re-emergence. Ekman upwelling and shear-induced mixing are especially significant in the tropical oceans, and account for 19% and 18% of the total tracer re-emergence, respectively. There is substantial regional variation in the relative importance of the various upwelling mechanisms. Special attention is devoted to understanding the contrasting circulations of SAMW in the North Pacific and North Atlantic oceans. The modest penetration of SAMW into the North Pacific is found to arise from the comparatively light density level that the SAMW core resides at in the South Pacific Ocean, which results in its being captured by the Equatorial Undercurrent and prevents it from entering the western boundary current of the North Pacific. In the North Atlantic, a new conceptual model of SAMW circulation and re-emergence is proposed with application to nutrient supply to the regional upper ocean. The model formulates SAMW re-emergence as a sequence of distinct processes following the seasonal cycle of the thermocline as a water column circulates around the subtropical and subpolar gyres of the North Atlantic.

  1. M.mode.ify: A Free Online Tool to Generate Post Hoc M-Mode Images From Any Ultrasound Clip.

    PubMed

    Smith, Benjamin C; Avila, Jacob

    2016-02-01

    We present a software tool designed to generate an M-mode image post hoc from any B-mode ultrasound clip, along any possible axis. M.mode.ify works by breaking down an ultrasound clip into individual frames. It then rotates and crops these frames by using a user-selected M-mode line. The post hoc M-mode image is created by splicing these frames together. Users can measure time and distance after proper calibration through the M.mode.ify interface. This tool opens up new possibilities for clinical application, quality assurance, and research. It is available free for public use at http://www.ultrasoundoftheweek.com/M.mode.ify/.

  2. Versatile Coordination Mode of a New Pyridine-Based Ditopic Ligand with Transition Metals: From Regular Pyridine to Alkyne and Alkenyl Bindings and Indolizinium Formation.

    PubMed

    Kumar, Sushil; Mandon, Dominique

    2015-08-03

    The new BPMPB ligand, namely, bis[1-bis(2-pyridylmethyl),1 (pyridyl)]butyne, can be very easily obtained as a side product in the known reaction of picolyl chloride and sodium acetylide (which major product is the known terminal alkyne-substituted tripod). This symmetrical ligand contains two identical coordination sites with two methylenepyridines and one pyridyl group on each side, linked by an alkyne function providing a semirigid segment. Together with the molecular structure of the ligand which is reported, we describe the preparation of complexes with Fe(II)Cl2, Co(II)Cl2, Ni(II)Cl2, Cu(I)Cl, and Zn(II)Cl2 salts. All complexes have been characterized by X-ray diffraction studies as well as by standard spectroscopic techniques. The striking point in this work is the diversity of the structures that are obtained. Co(II) and Zn(II) provide isostructural dinuclear complexes in which both coordination sites are occupied within a tetrahedral symmetry. The Cu(I) complex is also a dinuclear compound, but in that case, the copper atom is coordinated to the alkyne moiety, two pyridines, and a bridging chloride. The (13)C NMR spectrum of the copper complex confirms that the metal center is coordinated to the alkyne in solution. The coordination of Ni(II) results in the formation of a mononuclear complex in which a pyridine has fused with the alkyne moiety to generate an indolizinium group; the structure of the corresponding alkenyl complex is reported. Finally, the addition of FeCl2 to the ligand results in the formation of a mononuclear complex with a free, noncoordinated indolizinium. The sequence developed in the present work illustrates the possibility for the metal centers to adopt various coordination modes which may be relevant to the conversion of an alkyne and a pyridyl unit into indolizinium.

  3. Mod 1 wind turbine generator failure modes and effects analysis

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A failure modes and effects analysis (FMEA) was directed primarily at identifying those critical failure modes that would be hazardous to life or would result in major damage to the system. Each subsystem was approached from the top down, and broken down to successive lower levels where it appeared that the criticality of the failure mode warranted more detail analysis. The results were reviewed by specialists from outside the Mod 1 program, and corrective action taken wherever recommended.

  4. Nonadiabatic generator-coordinate calculation of H/sub 2/ /sup +/

    SciTech Connect

    Ribeiro Tostes, J.G.; de Toledo Piza, A.F.R.

    1983-08-01

    We report on a nonadiabatic calculation of the few lowest J = 0 states in the H/sub 2/ /sup +/ molecule done within the framework of the generator-coordinate method. Substantial accuracy is achieved with the diagonalization of matrices of very modest dimensions. The resulting wave functions are strongly dominated by just a few basis states. The computational scheme is set up so as to take the best advantage of good analytical approximations to existing adiabatic molecular wave functions.

  5. Generator coordinate method and nuclear collective motions (IV)-TDGCM versus ATDHF

    SciTech Connect

    Xu, G.

    1982-04-01

    Considering the time-dependent generator coordinate method, the time-dependent Schroedinger equation for nuclear collective motions is obtained. It is then possible to obtain through the Wigner matrix a variational expression for mean collective properties q-bar(t) and p-bar(t) in classical limits. Under adiabatic approximation this is just the expression by which Villars has obtained the ATDHF results.

  6. On the generation of internal wave modes by surface waves

    NASA Astrophysics Data System (ADS)

    Harlander, Uwe; Kirschner, Ian; Maas, Christian; Zaussinger, Florian

    2016-04-01

    Internal gravity waves play an important role in the ocean since they transport energy and momentum and the can lead to mixing when they break. Surface waves and internal gravity waves can interact. On the one hand, long internal waves imply a slow varying shear current that modifies the propagation of surface waves. Surface waves generated by the atmosphere can, on the other hand, excite internal waves by nonlinear interaction. Thereby a surface wave packet consisting of two close frequencies can resonate with a low frequency internal wave (Phillips, 1966). From a theoretical point of view, the latter has been studied intensively by using a 2-layer model, i.e. a surface layer with a strong density contrast and an internal layer with a comparable weak density contrast (Ball, 1964; Craig et al., 2010). In the present work we analyse the wave coupling for a continuously stratified fluid using a fully non-linear 2D numerical model (OpenFoam) and compare this with laboratory experiments (see Lewis et al. 1974). Surface wave modes are used as initial condition and the time development of the dominant surface and internal waves are studied by spectral and harmonic analysis. For the simple geometry of a box, the results are compared with analytical spectra of surface and gravity waves. Ball, F.K. 1964: Energy transfer between external and internal gravity waves. J. Fluid Mech. 19, 465. Craig, W., Guyenne, P., Sulem, C. 2010: Coupling between internal and surface waves. Natural Hazards 57, 617-642. Lewis, J.E., Lake, B.M., Ko, D.R.S 1974: On the interaction of internal waves and surfacr gravity waves, J. Fluid Mech. 63, 773-800. Phillips, O.M. 1966: The dynamics of the upper ocean, Cambridge University Press, 336pp.

  7. Compare and contrast the reaction coordinate diagrams for chemical reactions and cytoskeletal force generators

    PubMed Central

    Scholey, Jonathan M.

    2013-01-01

    Reaction coordinate diagrams are used to relate the free energy changes that occur during the progress of chemical processes to the rate and equilibrium constants of the process. Here I briefly review the application of these diagrams to the thermodynamics and kinetics of the generation of force and motion by cytoskeletal motors and polymer ratchets as they mediate intracellular transport, organelle dynamics, cell locomotion, and cell division. To provide a familiar biochemical context for discussing these subcellular force generators, I first review the application of reaction coordinate diagrams to the mechanisms of simple chemical and enzyme-catalyzed reactions. My description of reaction coordinate diagrams of motors and polymer ratchets is simplified relative to the rigorous biophysical treatment found in many of the references that I use and cite, but I hope that the essay provides a valuable qualitative representation of the physical chemical parameters that underlie the generation of force and motility at molecular scales. In any case, I have found that this approach represents a useful interdisciplinary framework for understanding, researching, and teaching the basic molecular mechanisms by which motors contribute to fundamental cell biological processes. PMID:23408787

  8. Quantum statistics of Raman scattering model with Stokes mode generation

    NASA Technical Reports Server (NTRS)

    Tanatar, Bilal; Shumovsky, Alexander S.

    1994-01-01

    The model describing three coupled quantum oscillators with decay of Rayleigh mode into the Stokes and vibration (phonon) modes is examined. Due to the Manley-Rowe relations the problem of exact eigenvalues and eigenstates is reduced to the calculation of new orthogonal polynomials defined both by the difference and differential equations. The quantum statistical properties are examined in the case when initially: the Stokes mode is in the vacuum state; the Rayleigh mode is in the number state; and the vibration mode is in the number of or squeezed states. The collapses and revivals are obtained for different initial conditions as well as the change in time the sub-Poisson distribution by the super-Poisson distribution and vice versa.

  9. Generation of two-mode squeezed states for two separated atomic ensembles via coupled cavities

    SciTech Connect

    Zheng Shibiao; Yang Zhenbiao; Xia Yan

    2010-01-15

    We propose an efficient scheme for the generation of two-mode squeezed states for two separated atomic ensembles trapped in distant cavities. The scheme is based on selective couplings between the collective atomic modes and two linearly transformed common field modes mediated by an optical fiber or a third cavity. The quanta of the transformed atomic modes are exhausted due to the linear coupling with the transformed field modes, bringing the original atomic modes into the two-mode squeezed states. The experimental implementation of the scheme would be an important step toward quantum communication and networking with continuous variables.

  10. Mode converters for generating the HE11 (near-Gaussian) mode from gyrotron TEOn modes at 140 GHz

    NASA Astrophysics Data System (ADS)

    Thumm, M.; Sturm, H.

    1985-11-01

    The structure of wall perturbations (superposition of 2 or 3 different periods) in rippled wall mode converters and the curvature distribution in bent smooth-walled TEO1-to-TM11 mode transducers were optimized by numerically solving the corresponding coupled-mode differential equations. Computer-aided optimization of circumferentially corrugated mode converters was achieved with a scattering matrix code employing the modal field expansion technique. In all cases the predicted overall efficiency of the complete mode converter system from Sigma TEOn (predominantly TEO3) to HE11 in the desired mode is 90% to 92% (ohmic attenuation is included). Low-power measurements on the efficiency of a 140 GHz TEO1-to-TM11 mode transducer (ao = 13.9 mm) are in excellent agreement with the predicted value of 95.2% (including ohmic attenuation).

  11. Central generation of grooming motor patterns and interlimb coordination in locusts.

    PubMed

    Berkowitz, A; Laurent, G

    1996-12-15

    Coordinated bursts of leg motoneuron activity were evoked in locusts with deefferented legs by tactile stimulation of sites that evoke grooming behavior. This suggests that insect thoracic ganglia contain central pattern generators for directed leg movements. Motoneuron recordings were made from metathoracic and mesothoracic nerves, after eliminating all leg motor innervation, as well as all input from the brain, subesophageal ganglion, and prothoracic ganglion. Strong, brief trochanteral levator motoneuron bursts occurred, together with silence of the slow and fast trochanteral depressor motoneurons and activation of the common inhibitor motoneuron. The metathoracic slow tibial extensor motoneuron was active in a pattern distinct from its activity during walking or during rhythms evoked by the muscarinic agonist pilocarpine. Preparations in which the metathoracic ganglion was isolated from all other ganglia could still produce fictive motor patterns in response to tactile stimulation of metathoracic locations. Bursts of trochanteral levator and depressor motoneurons were clearly coordinated between the left and right metathoracic hemiganglia and also between the mesothoracic and the ipsilateral metathoracic ganglia. These data provide clear evidence for centrally generated interlimb coordination in an insect.

  12. Dynamic modes of microwave signal autogeneration in a radio photonic ring generator

    NASA Astrophysics Data System (ADS)

    Kondrashov, A. V.; Ustinov, A. B.; Kalinikos, B. A.

    2017-02-01

    Dynamic modes of microwave signal autogeneration in a radio photonic generator have been investigated. The generator is a ring circuit with a low-pass filter and microwave amplifier in its microwave path. The optical path contains an optical fiber delay line. The generator demonstrates the periodical, chaotic, and noise dynamics. It has been shown that the correlation dimensionality of the random signal attractor in the chaotic generation mode saturates with increasing phase space dimensionality. Saturation is not observed in the noise-generation mode.

  13. Efficient and direct generation of multidimensional free energy surfaces via adiabatic dynamics without coordinate transformations.

    PubMed

    Abrams, Jerry B; Tuckerman, Mark E

    2008-12-11

    Adiabatic free energy dynamics (AFED) was introduced by Rosso et al. [J. Chem. Phys. 2002, 116, 4389] for computing free energy profiles quickly and accurately using a dynamical adiabatic separation between a set of collective variables or reaction coordinates and the remaining degrees of freedom of a system. This approach has been shown to lead to a significant gain in efficiency versus traditional methods such as umbrella sampling, thermodynamic integration, and free energy perturbation for generating one-dimensional free energy profiles. More importantly, AFED is able to generate multidimensional free energy surfaces efficiently via full sweeps of the surface that rapidly map out the locations of the free energy minima. The most significant drawback to the AFED approach is the need to transform the coordinates into a generalized coordinate system that explicitly contains the collective variables of interest. Recently, Maragliano and Vanden-Eijnden built upon the AFED approach by introducing a set of extended phase-space variables, to which the adiabatic decoupling and high temperature are applied [Chem. Phys. Lett. 2006, 426, 168]. In this scheme, which the authors termed "temperature accelerated molecular dynamics" or TAMD, the need for explicit coordinate transformations is circumvented. The ability of AFED and TAMD to generate free energy surfaces efficiently depends on the thermostatting mechanism employed, since both approaches are inherently nonequilibrium due to the adiabatic decoupling. Indeed, Maragliano and Vanden-Eijnden did not report any direct generation of free energy surfaces within the overdamped Langevin dynamics employed by these authors. Here, we show that by formulating TAMD in a manner that is closer to the original AFED approach, including the generalized Gaussian moment thermostat (GGMT) and multiple time-scale integration, multidimensional free energy surfaces for complex systems can be generated directly from the probability

  14. Resonant generation of topological modes in trapped Bose-Einstein gases

    SciTech Connect

    Yukalov, V.I.; Marzlin, K.-P.; Yukalova, E.P.

    2004-02-01

    Trapped atoms cooled down to temperatures below the Bose-Einstein condensation temperature are considered. Stationary solutions to the Gross-Pitaevskii equation (GPE) define the topological coherent modes, representing nonground-state Bose-Einstein condensates. These modes can be generated by means of alternating fields whose frequencies are in resonance with the transition frequencies between two collective energy levels corresponding to two different topological modes. The theory of resonant generation of these modes is generalized in several aspects: Multiple-mode formation is described; a shape-conservation criterion is derived, imposing restrictions on the admissible spatial dependence of resonant fields; evolution equations for the case of three coherent modes are investigated; the complete stability analysis is accomplished; the effects of harmonic generation and parametric conversion for the topological coherent modes are predicted. All considerations are realized both by employing approximate analytical methods as well as by numerically solving the GPE. Numerical solutions confirm all conclusions following from analytical methods.

  15. Interaction of Lamb mode (A(o)) with structural discontinuity and generation of "Turning modes" in a T-joint.

    PubMed

    Ramadas, C; Balasubramaniam, Krishnan; Joshi, M; Krishnamurthy, C V

    2011-07-01

    In the present work, the interaction of the fundamental anti-symmetric guided Lamb mode (A(o)) with a structural discontinuity in a composite structure was studied through Finite Element numerical simulations and experiments. The structural component selected for this study was a T-joint section made from glass/epoxy material. This co-cured composite structure is made-up of an upper shell (skin) and a spar as the sub-components. It was observed that when A(o) mode interacts with the junction (structural discontinuity) of these sub-components, a mode-converted S(o) mode is generated. Experiments were conducted using air-coupled ultrasound to validate the numerical simulations. The back-propagating "Turning modes", which propagate from the thin region to the spar web and vice versa, were also numerically simulated and experimentally verified.

  16. Mode converters for generating the HE11 (gaussian-like) mode from TE01 in circular waveguide

    SciTech Connect

    Doane, J.L.

    1982-09-01

    The HE11 mode in corrugated waveguide has a field distribution very close to that of an ideal gaussian mode. Its radiation pattern is symmetric about the waveguide axis and exhibits virtually no cross polarization. This work reports measurements on mode converters to transform the TE01 mode into HE11 for electron cyclotron heating (ECH) experiments. The first mode converter is a 28 degree bend in 1.094-inch I.D. circular waveguide which generates TM11 from TE01 with a measured efficiency of over 95% at 60 GHz. A second converter consists of a straight corrugated waveguide section of the same I.D. in which the corrugation depth increases gradually from zero to nominally a quarter wavelength. This section converts TM11 to HE11 with an efficiency of about 97%. The overall efficiency of conversion from TE01 to HE11 exceeds 91% over a measured range of 59.2 to 60.1 GHz.

  17. Supply chain coordination with two production modes and random demand depending on advertising expenditure and selling price

    NASA Astrophysics Data System (ADS)

    Wang, Sheng-Dong; Zhou, Yong-Wu; Wang, Jun-Ping

    2010-10-01

    This article discusses production and order as well as advertising coordination issues in a single-manufacturer single-buyer supply chain, where the manufacturer sells a newsvendor-type product through the buyer who faces a random demand depending on advertising expenditure and selling price. The buyer has two ordering opportunities: the one happens before the beginning of the season, and the other takes place at the end of the season. The ordered items are produced by the manufacturer in two production modes for different requirements. The first production mode is relatively cheap but requires a long lead-time, whereas the second is expensive but offers quick response. Under such a setting, the centralised and decentralised decision models are developed, respectively, and the closed form solution to each model is provided as well. Moreover, we point out that the traditional revenue-sharing contract fails to coordinate the supply chain. We thus propose an improved revenue-sharing contract that requests the manufacturer not only shares the buyer's revenue but also bears a portion of the buyer's operating costs. Such a contract can achieve perfect coordination of the supply chain and arbitrarily allocate its profit between two parties.

  18. Documentation of program COORDC to generate and coordinate system for 3D corners with or without fillet using body fitted curvilinear coordinates, part 2

    NASA Technical Reports Server (NTRS)

    Kumar, D.

    1980-01-01

    The computer program COORDC generates a body fitted curvilinear coordinate system for corner geometry with or without corner fillets. It is assumed that at any given xi, x remains constant; consequently the only variation is in y and z. It is also assumed that for all xi's in the physical plane the coordinate system in y-z plane is similar. This enables solution of coordinate system for one particular xi = 1 (x for xi = 1 is arbitrarily chosen to be 0.0) and the solution for all other xi plane can be easily specified once the coordinates in the physical plane on the line 1 or = to xi or = to IMAX, eta = 1, zeta = 1 are specified.

  19. Ultra Short-term Prediction of Pole Coordinates via Combination of Empirical Mode Decomposition and Neural Networks

    NASA Astrophysics Data System (ADS)

    Lei, Yu; Zhao, Danning; Cai, Hongbing

    2016-12-01

    It was shown in the previous study that the increase of pole coordinates prediction error for about 100 days in the future is mostly caused by irregular short period oscillations. In this paper, the ultra short-term prediction of pole coordinates is studied for 10 days in the future by means of combination of empirical mode decomposition (EMD) and neural networks (NN), denoted EMD-NN. In the algorithm, EMD is employed as a low pass filter for eliminating high frequency signals from observed pole coordinates data. Then the annual and Chandler wobbles are removed a priori from pole coordinates data with high frequency signals eliminated. Finally, the radial basis function (RBF) networks are used to model and predict the residuals. The prediction performance of the EMD-NN approach is compared with that of the NN-only solution and the prediction methods and techniques involved in the Earth orientation parameters prediction comparison campaign (EOP PCC). The results show that the prediction accuracy of the EMD-NN algorithm is better than that of the NN-only solution and is also comparable with that of the other existing prediction method and techniques.

  20. User's manual for Axisymmetric Diffuser Duct (ADD) code. Volume 3: ADD code coordinate generator

    NASA Technical Reports Server (NTRS)

    Anderson, O. L.; Hankins, G. B., Jr.; Edwards, D. E.

    1982-01-01

    This User's Manual contains a complete description of the computer codes known as the Axisymmetric Diffuser Duct (ADD) code. It includes a list of references which describe the formulation of the ADD code and comparisons of calculation with experimental flows. The input/output and general use of the code is described in the first volume. The second volume contains a detailed description of the code including the global structure of the code, list of FORTRAN variables, and descriptions of the subroutines. The third volume contains a detailed description of the CODUCT code which generates coordinate systems for arbitrary axisymmetric ducts.

  1. Application of the generator coordinate method to neutron-rich Se and Ge isotopes

    NASA Astrophysics Data System (ADS)

    Higashiyama, Koji; Yoshinaga, Naotaka

    2014-03-01

    The quantum-number projected generator coordinate method (GCM) is applied to the neutron-rich Se and Ge isotopes, where the monopole and quadrupole pairing plus quadrupole-quadrupole interaction is employed as an effective interaction. The energy spectra obtained by the GCM are compared to both the shell model results and the experimental data. The GCM reproduces well the energy levels of high-spin states as well as the low-lying states. The structure of the low-lying collective states is analyzed through the GCM wave functions.

  2. Frequency comb generation by CW laser injection into a quantum-dot mode-locked laser.

    PubMed

    Pinkert, T J; Salumbides, E J; Tahvili, M S; Ubachs, W; Bente, E A J M; Eikema, K S E

    2012-09-10

    We report on frequency comb generation at 1.5 μm by injection of a CW laser in a hybridly mode-locked InAs/InP two-section quantum-dot laser (HMLQDL). The generated comb has > 60 modes spaced by ∼ 4.5 GHz and a -20 dBc width of > 100 GHz (23 modes) at > 30 dB signal to background ratio. Comb generation was observed with the CW laser (red) detuned more than 20 nm outside the HMLQDL spectrum, spanning a large part of the gain spectrum of the quantum dot material. It is shown that the generated comb is fully coherent with the injected CW laser and RF frequency used to drive the hybrid mode-locking. This method of comb generation is of interest for the creation of small and robust frequency combs for use in optical frequency metrology, high-frequency (> 100 GHz) RF generation and telecommunication applications.

  3. Redox cycling of copper-amyloid β 1-16 peptide complexes is highly dependent on the coordination mode.

    PubMed

    Trujano-Ortiz, Lidia G; González, Felipe J; Quintanar, Liliana

    2015-01-05

    Copper (Cu)-amyloid β (Aβ) interactions play a role in the etiology of Alzheimer's disease. This work presents a spectroscopic and electrochemical study of two physiologically relevant Aβ-Cu(II) complexes, as a function of pH and relative Cu-Aβ(1-16) concentrations. Our results reveal that these coordination modes display distinct redox behaviors and provide experimental evidence for the existence of an intermediate Cu(I) species. A mechanism for the redox cycling of these complexes is proposed, providing further insight into the redox relevance of Aβ-Cu interactions.

  4. Retrieval Mode Distinguishes the Testing Effect from the Generation Effect

    ERIC Educational Resources Information Center

    Karpicke, Jeffrey D.; Zaromb, Franklin M.

    2010-01-01

    A series of four experiments examined the effects of generation vs. retrieval practice on subsequent retention. Subjects were first exposed to a list of target words. Then the subjects were shown the targets again intact for Read trials or they were shown fragments of the targets. Subjects in Generate conditions were told to complete the fragments…

  5. Porous solids arising from synergistic and competing modes of assembly: combining coordination chemistry and covalent bond formation.

    PubMed

    Dutta, Ananya; Koh, Kyoungmoo; Wong-Foy, Antek G; Matzger, Adam J

    2015-03-23

    Design and synthesis of porous solids employing both reversible coordination chemistry and reversible covalent bond formation is described. The combination of two different linkage modes in a single material presents a link between two distinct classes of porous materials as exemplified by metal-organic frameworks (MOFs) and covalent organic frameworks (COFs). This strategy, in addition to being a compelling material-discovery method, also offers a platform for developing a fundamental understanding of the factors influencing the competing modes of assembly. We also demonstrate that even temporary formation of reversible connections between components may be leveraged to make new phases thus offering design routes to polymorphic frameworks. Moreover, this approach has the striking potential of providing a rich landscape of structurally complex materials from commercially available or readily accessible feedstocks.

  6. Coordination between Generation and Transmission Maintenance Scheduling by Means of Multi-agent Technique

    NASA Astrophysics Data System (ADS)

    Nagata, Takeshi; Tao, Yasuhiro; Utatani, Masahiro; Sasaki, Hiroshi; Fujita, Hideki

    This paper proposes a multi-agent approach to maintenance scheduling in restructured power systems. The restructuring of electric power industry has resulted in market-based approaches for unbundling a multitude of service provided by self-interested entities such as power generating companies (GENCOs), transmission providers (TRANSCOs) and distribution companies (DISCOs). The Independent System Operator (ISO) is responsible for the security of the system operation. The schedule submitted to ISO by GENCOs and TRANSCOs should satisfy security and reliability constraints. The proposed method consists of several GENCO Agents (GAGs), TARNSCO Agents (TAGs) and a ISO Agent(IAG). The IAG’s role in maintenance scheduling is limited to ensuring that the submitted schedules do not cause transmission congestion or endanger the system reliability. From the simulation results, it can be seen the proposed multi-agent approach could coordinate between generation and transmission maintenance schedules.

  7. Self-mode-locked chromium-doped forsterite laser generates 50-fs pulses

    NASA Technical Reports Server (NTRS)

    Seas, A.; Petricevic, V.; Alfano, R. R.

    1993-01-01

    Stable transform-limited (delta nu-delta tau = 0.32) femtosecond pulses with a FWHM of 50 fs were generated from a self-mode-locked chromium-doped forsterite laser. The forsterite laser was synchronously pumped by a CW mode-locked Nd:YAG (82 MHz) laser that generated picosecond pulses (200-300 ps) and provided the starting mechanism for self-mode-locked operation. Maximum output power was 45 mW for 3.9 W of absorbed pumped power with the use of an output coupler with 1 percent transmission. The self-mode-locked forsterite laser was tuned from 1240 to 1270 nm.

  8. Magnetic fields generated by r-modes in accreting millisecond pulsars

    SciTech Connect

    Cuofano, Carmine; Drago, Alessandro

    2010-10-15

    In rotating neutron stars the existence of the Coriolis force allows the presence of the so-called Rossby oscillations (r-modes) which are known to be unstable to emission of gravitational waves. Here, for the first time, we introduce the magnetic damping rate in the evolution equations of r-modes. We show that r-modes can generate very strong toroidal fields in the core of accreting millisecond pulsars by inducing differential rotation. We shortly discuss the instabilities of the generated magnetic field and its long time-scale evolution in order to clarify how the generated magnetic field can stabilize the star.

  9. Generation of three-mode nonclassical vibrational states of ions

    SciTech Connect

    Nguyen Ba An; Truong Minh Duc

    2002-12-01

    We propose using eight lasers with appropriate orientations and conditions to generate stable trio coherent states of an ion in a three-dimensional isotropic trap. Seven lasers whose orientations are important should be detuned to the third lower sideband of the ion vibrational motion. The eighth laser whose direction is not important should be in resonance with the ionic transition.

  10. Controlled generation of intrinsic localized modes in microelectromechanical cantilever arrays

    NASA Astrophysics Data System (ADS)

    Chen, Qingfei; Lai, Ying-Cheng; Dietz, David

    2010-12-01

    We propose a scheme to induce intrinsic localized modes (ILMs) at an arbitrary site in microelectromechanical cantilever arrays. The idea is to locate the particular cantilever beam in the array that one wishes to drive to an oscillating state with significantly higher amplitude than the average and then apply small adjustments to the electrical signal that drives the whole array system. Our scheme is thus a global closed-loop control strategy. We argue that the dynamical mechanism on which our global driving scheme relies is spatiotemporal chaos and we develop a detailed analysis based on the standard averaging method in nonlinear dynamics to understand the working of our control scheme. We also develop a Markov model to characterize the transient time required for inducing ILMs.

  11. A possibility for using an APPLE undulator to generate a photon beam with transverse optical modes.

    SciTech Connect

    Sasaki, S.; McNulty, I.; Shimada, T.; JAEA

    2008-01-01

    We investigate use of an APPLE-type undulator for generating Laguerre-Gaussian (LG) and Hermite-Gaussian (HG) mode beams. We find that the second harmonic radiation in the circular mode corresponds to an LG beam with l=1, and the second harmonic in the linear mode corresponds to an HG beam with l=1. The combination of an APPLE undulator and conventional monochromator optics may provide an opportunity for a new type of experimental research in the synchrotron radiation community.

  12. Coordination functionalization of graphene oxide with tetraazamacrocyclic complexes of nickel(II): Generation of paramagnetic centers

    NASA Astrophysics Data System (ADS)

    Basiuk, Vladimir A.; Alzate-Carvajal, Natalia; Henao-Holguín, Laura V.; Rybak-Akimova, Elena V.; Basiuk, Elena V.

    2016-05-01

    We describe a novel approach to functionalization of graphene oxide (GO) which allows for a facile generation of paramagnetic centers from two diamagnetic components. Coordination attachment of [Ni(cyclam)]2+ or [Ni(tet b)]2+ tetraazamacrocyclic cations to carboxylic groups of GO takes place under basic conditions in aqueous-based reaction medium. The procedure is very straightforward and does not require high temperatures or other harsh conditions. Changing the coordination geometry of Ni(II) from square-planar tetracoordinated to pseudooctahedral hexacoordinated brings about the conversion from low-spin to high-spin state of the metal centers. Even though the content of tetraazamacrocyclic complexes in functionalized GO samples was found to be relatively low (nickel content of ca. 1 wt%, as determined by thermogravimetric analysis, elemental analysis and energy dispersive X-ray spectroscopy), room temperature magnetic susceptibility measurements easily detected the appearance of paramagnetic properties in GO + [Ni(cyclam)] and GO + [Ni(tet b)] nanohybrids, with effective magnetic moments of 1.95 BM and 2.2 BM for, respectively. According to density functional theory calculations, the main spin density is localized at the macrocyclic complexes, without considerable extension to graphene sheet, which suggests insignificant ferromagnetic coupling in the nanohybrids, in agreement with the results of magnetic susceptibility measurements. The coordination attachment of Ni(II) tetraazamacrocycles to GO results in considerable changes in Fourier-transform infrared and X-ray photoelectron spectra, as well as in GO morphology, as observed by scanning and transmission electron microscopy, atomic force and scanning tunneling microscopy.

  13. Radiation characteristics and generation of higher-order modes of circular microstrip antennas

    NASA Astrophysics Data System (ADS)

    Kumar, G.; Shafai, L.

    1984-08-01

    The characteristics of higher-order modes of circular microstrip antennas, such as radiation pattern, directivity, bandwidth, efficiency, and location of the feedpoint to match a 50 ohm line, are studied, and the effects of varying the substrate parameters are investigated. A multifeed technique to generate any particular mode is also presented.

  14. Internal breather-like wave generation by the second mode solitary wave interaction with a step

    NASA Astrophysics Data System (ADS)

    Terletska, Kateryna; Jung, Kyung Tae; Talipova, Tatiana; Maderich, Vladimir; Brovchenko, Igor; Grimshaw, Roger

    2016-11-01

    The transformation of an internal second mode solitary wave over a bottom step in a computational tank filled with a three-layer stratified fluid was studied. The convex waveforms were generated by a collapse mechanism for stratification with a thin mid-layer. The wave transformation depends on the blocking parameter B which is a ratio of the amplitude of the incident wave to the thickness of the lower water layer over the step. Three regimes of second mode wave transformation over the step are identified. In regime I (2 < B < 6) this wave generates a breather-like internal wave (BLIW) packet behind the wave of mode-2 due to the impulse-like effect of the step and a long wave of mode-1 ahead of the wave. The BLIW degenerates into a dispersive wave packet at large B > 6. In regime II (0.5 < B < 2) the mode-2 wave is permanently disintegrated, generating a chain of waves of mode-1 ahead of wave of mode-2 and tail of short waves of mode-1 behind the wave. In regime III (B < 0.5) only waves of elevation of mode-1 penetrate into the fluid layer over the step.

  15. Colorimetric and Fluorescent Dual Mode Sensing of Alcoholic Strength in Spirit Samples with Stimuli-Responsive Infinite Coordination Polymers.

    PubMed

    Deng, Jingjing; Ma, Wenjie; Yu, Ping; Mao, Lanqun

    2015-07-07

    This study demonstrates a new strategy for colorimetric and fluorescent dual mode sensing of alcoholic strength (AS) in spirit samples based on stimuli-responsive infinite coordination polymers (ICPs). The ICP supramolecular network is prepared with 1,4-bis(imidazol-1-ylmethyl)benzene (bix) as the ligand and Zn(2+) as the central metal ion in ethanol, in which rhodamine B (RhB) is encapsulated through self-adaptive chemistry. In pure ethanol solvent, the as-formed RhB/Zn(bix) is well dispersed and quite stable. However, the addition of water into the ethanol dispersion of RhB/Zn(bix) destroys Zn(bix) network structure, resulting in the release of RhB from ICP into the solvent. As a consequence, the solvent displays the color of released RhB and, at the meantime, turns on the fluorescence of RhB, which constitutes a new mechanism for colorimetric and fluorescent dual mode sensing of AS in commercial spirit samples. With the method developed here, we could distinguish the AS of different commercial spirit samples by the naked eye within a wide linear range from 20 to 100% vol and by monitoring the increase of fluorescent intensity of the released RhB. This study not only offers a new method for on-spot visible detection of AS in commercial spirit samples, but also provides a strategy for designing dual mode sensing mechanisms for different analytical purposes based on novel stimuli-responsive materials.

  16. The experimental studies of operating modes of a diesel-generator set at variable speed

    NASA Astrophysics Data System (ADS)

    Obukhov, S. G.; Plotnikov, I. A.; Surkov, M. A.; Sumarokova, L. P.

    2017-02-01

    A diesel generator set working at variable speed to save fuel is studied. The results of experimental studies of the operating modes of an autonomous diesel generator set are presented. Areas for regulating operating modes are determined. It is demonstrated that the transfer of the diesel generator set to variable speed of the diesel engine makes it possible to improve the energy efficiency of the autonomous generator source, as well as the environmental and ergonomic performance of the equipment as compared with general industrial analogues.

  17. Next-generation applications in healthcare digital libraries using semantic service composition and coordination.

    PubMed

    Möller, Thorsten; Schuldt, Heiko; Gerber, Andreas; Klusch, Matthias

    2006-06-01

    Healthcare digital libraries (DLs) increasingly make use of dedicated services to access functionality and/or data. Semantic (web) services enhance single services and facilitate compound services, thereby supporting advanced applications on top of a DL. The traditional process management approach tends to focus on process definition at build time rather than on actual service events in run time, and to anticipate failures in order to define appropriate strategies. This paper presents a novel approach where service coordination is distributed among a set of agents. A dedicated component plans compound semantic services on demand for a particular application. In failure, the planner is reinvoked to define contin- gency strategies. Finally, matchmaking is effected at runtime by choosing the appropriate service provider. These combined technologies will provide key support for highly flexible next-generation DL applications. Such technologies are under development within CASCOM.

  18. The generator coordinate Dirac-Fock method for open-shell atomic systems

    NASA Astrophysics Data System (ADS)

    Malli, Gulzari L.; Ishikawa, Yasuyuki

    1998-11-01

    Recently we developed generator coordinate Dirac-Fock and Dirac-Fock-Breit methods for closed-shell systems assuming finite nucleus and have reported Dirac-Fock and Dirac-Fock-Breit energies for the atoms He through Nobelium (Z=102) [see Refs. Reference 10Reference 11Reference 12Reference 13]. In this paper, we generalize our earlier work on closed-shell systems and develop a generator coordinate Dirac-Fock method for open-shell systems. We present results for a number of representative open-shell heavy atoms (with nuclear charge Z>80) including the actinide and superheavy transactinide (with Z>103) atomic systems: Fr (Z=87), Ac (Z=89), and Lr (Z=103) to E113 (eka-thallium, Z=113). The high accuracy obtained in our open-shell Dirac-Fock calculations is similar to that of our closed-shell calculations, and we attribute it to the fact that the representation of the relativistic dynamics of an electron in a spherical ball finite nucleus near the origin in terms of our universal Gaussian basis set is as accurate as that provided by the numerical finite difference method. The DF SCF energies calculated by Desclaux [At. Data. Nucl. Data Tables 12, 311 (1973)] (apart from a typographic error for Fr pointed out here) are higher than those reported here for atoms of some of the superheavy transactinide elements by as much as 5 hartrees (136 eV). We believe that this is due to the use by Desclaux of much larger atomic masses than the currently accepted values for these elements.

  19. Highly Axial Magnetic Anisotropy in a N3 O5 Dysprosium(III) Coordination Environment Generated by a Merocyanine Ligand.

    PubMed

    Selvanathan, Pramila; Huang, Gang; Guizouarn, Thierry; Roisnel, Thierry; Fernandez-Garcia, Guglielmo; Totti, Federico; Le Guennic, Boris; Calvez, Guillaume; Bernot, Kévin; Norel, Lucie; Rigaut, Stéphane

    2016-10-17

    A spiropyran-based switchable ligand isomerizes upon reaction with lanthanide(III) precursors to generate complexes with an unusual N3 O5 coordination sphere. The air-stable dysprosium(III) complex shows a hysteresis loop at 2 K and a very strong axial magnetic anisotropy generated by the merocyanine phenolate donor.

  20. Use of numerically generated body-fitted coordinate systems for solution of the Navier-Stokes equations

    NASA Technical Reports Server (NTRS)

    Thompson, J. F.; Mastin, C. W.; Thames, F. C.; Shanks, S. P.

    1975-01-01

    A procedure for numerical solution of the time-dependent, two-dimensional incompressible Navier-Stokes equations that can treat the unsteady laminar flow about bodies of arbitrary shape, such as two-dimensional airfoils, multiple airfoils, and submerged hydrofoils, as naturally as it can deal with the flow about simple bodies. The solution is based on a method of automatic numerical generation of a general curvilinear coordinate system with coordinate lines coincident with all boundaries of a general multiconnected region containing any number of arbitrarily shaped bodies. The curvilinear coordinates are generated as the solution of two elliptical partial differential equations with Dirichlet boundary conditions, one coordinate being specified to be constant on each of the boundaries, and a distribution of the other being specified along the boundaries. The solution compares excellently with the Blasius boundary layer solution for the flow past a semiinfinite flat plate.

  1. A simple cohesive zone model that generates a mode-mixity dependent toughness

    SciTech Connect

    Reedy, Jr., E. D.; Emery, J. M.

    2014-07-24

    A simple, mode-mixity dependent toughness cohesive zone model (MDGc CZM) is described. This phenomenological cohesive zone model has two elements. Mode I energy dissipation is defined by a traction–separation relationship that depends only on normal separation. Mode II (III) dissipation is generated by shear yielding and slip in the cohesive surface elements that lie in front of the region where mode I separation (softening) occurs. The nature of predictions made by analyses that use the MDGc CZM is illustrated by considering the classic problem of an elastic layer loaded by rigid grips. This geometry, which models a thin adhesive bond with a long interfacial edge crack, is similar to that which has been used to measure the dependence of interfacial toughness on crack-tip mode-mixity. The calculated effective toughness vs. applied mode-mixity relationships all display a strong dependence on applied mode-mixity with the effective toughness increasing rapidly with the magnitude of the mode-mixity. The calculated relationships also show a pronounced asymmetry with respect to the applied mode-mixity. As a result, this dependence is similar to that observed experimentally, and calculated results for a glass/epoxy interface are in good agreement with published data that was generated using a test specimen of the same type as analyzed here.

  2. A simple cohesive zone model that generates a mode-mixity dependent toughness

    DOE PAGES

    Reedy, Jr., E. D.; Emery, J. M.

    2014-07-24

    A simple, mode-mixity dependent toughness cohesive zone model (MDGc CZM) is described. This phenomenological cohesive zone model has two elements. Mode I energy dissipation is defined by a traction–separation relationship that depends only on normal separation. Mode II (III) dissipation is generated by shear yielding and slip in the cohesive surface elements that lie in front of the region where mode I separation (softening) occurs. The nature of predictions made by analyses that use the MDGc CZM is illustrated by considering the classic problem of an elastic layer loaded by rigid grips. This geometry, which models a thin adhesive bondmore » with a long interfacial edge crack, is similar to that which has been used to measure the dependence of interfacial toughness on crack-tip mode-mixity. The calculated effective toughness vs. applied mode-mixity relationships all display a strong dependence on applied mode-mixity with the effective toughness increasing rapidly with the magnitude of the mode-mixity. The calculated relationships also show a pronounced asymmetry with respect to the applied mode-mixity. As a result, this dependence is similar to that observed experimentally, and calculated results for a glass/epoxy interface are in good agreement with published data that was generated using a test specimen of the same type as analyzed here.« less

  3. Coordination modes in sensorimotor synchronization of whole-body movement: a study of street dancers and non-dancers.

    PubMed

    Miura, Akito; Kudo, Kazutoshi; Ohtsuki, Tatsuyuki; Kanehisa, Hiroaki

    2011-12-01

    This study investigated whole-body sensorimotor synchronization (SMS) in street dancers and non-dancers. Two kinds of knee bending movement in a standing position to a metronome beat were explored in terms of stability under different movement frequencies: down-movement condition (knee flexion on the beat) and up-movement condition (knee extension on the beat). Analyses of phase relation between movement and beat revealed several distinct differences between the down- and up-movement conditions, and between dancers and non-dancers. In both groups under the up-movement condition, deviation from intended phase relation at higher beat rates, and enhanced fluctuations were observed. The deviation from intended phase relation under up-movement condition, and movement fluctuations were greater in non-dancers than in dancers. Moreover, subjective difficulty rating revealed that both groups felt that the up-movement condition was more difficult at higher beat rates. These findings suggest that down and up movements are two distinguishable coordination modes in whole-body coordination, and that street dancers have superior whole-body SMS ability.

  4. Quorum sensing coordinates brute force and stealth modes of infection in the plant pathogen Pectobacterium atrosepticum.

    PubMed

    Liu, Hui; Coulthurst, Sarah J; Pritchard, Leighton; Hedley, Peter E; Ravensdale, Michael; Humphris, Sonia; Burr, Tom; Takle, Gunnhild; Brurberg, May-Bente; Birch, Paul R J; Salmond, George P C; Toth, Ian K

    2008-06-20

    Quorum sensing (QS) in vitro controls production of plant cell wall degrading enzymes (PCWDEs) and other virulence factors in the soft rotting enterobacterial plant pathogen Pectobacterium atrosepticum (Pba). Here, we demonstrate the genome-wide regulatory role of QS in vivo during the Pba-potato interaction, using a Pba-specific microarray. We show that 26% of the Pba genome exhibited differential transcription in a QS (expI-) mutant, compared to the wild-type, suggesting that QS may make a greater contribution to pathogenesis than previously thought. We identify novel components of the QS regulon, including the Type I and II secretion systems, which are involved in the secretion of PCWDEs; a novel Type VI secretion system (T6SS) and its predicted substrates Hcp and VgrG; more than 70 known or putative regulators, some of which have been demonstrated to control pathogenesis and, remarkably, the Type III secretion system and associated effector proteins, and coronafacoyl-amide conjugates, both of which play roles in the manipulation of plant defences. We show that the T6SS and a novel potential regulator, VirS, are required for full virulence in Pba, and propose a model placing QS at the apex of a regulatory hierarchy controlling the later stages of disease progression in Pba. Our findings indicate that QS is a master regulator of phytopathogenesis, controlling multiple other regulators that, in turn, co-ordinately regulate genes associated with manipulation of host defences in concert with the destructive arsenal of PCWDEs that manifest the soft rot disease phenotype.

  5. Concurrent multi-mode timing model generation for hierarchical timing analysis

    NASA Astrophysics Data System (ADS)

    Kumar, Naresh; Bhatnagar, Parag; Agarwal, N. K.; Bhatnagar, P. S.

    2016-03-01

    In this paper, we investigate the challenges in timing model generation for designs operating at various functional modes and timing corners for reducing the overall complexity of timing verification besides preserving the key intent of IP protection. We also propose a method for concurrently generating a model that can address the requirements of timing verification of a set of functional constraint modes belonging to the same corner with a given process, voltage and temperature specifications. Eventually we present a comparison of this proposed technique to the standard timing model generation technique and outline the advantages in three metrics of accuracy, performance and compaction of the timing models.

  6. Different generation regimes of mode-locked all-positive-dispersion all-fiber Yb laser

    NASA Astrophysics Data System (ADS)

    Kobtsev, Sergey; Kukarin, Sergey; Smirnov, Sergey; Turitsyn, Sergei; Latkin, Anton

    2010-02-01

    Different generation modes of all-positive-dispersion all-fibre Yb laser mode-locked due to effect of non-linear polarization evolution are investigated. For the first time we realized in the same laser both generation of single picoseconds pulse train and a newly observed lasing regime where generated are picosecond wave-packets, each being a train of femtosecond sub-pulses. Using both experimental results and numerical modeling we discuss in detail the mechanisms of laser mode-locking and switching of generation regimes and show a strong dependence of output laser characteristics on configuration of polarization controllers. A good qualitative agreement between experimental results and numerical modeling is demonstrated.

  7. Resistive wall tearing mode generated finite net electromagnetic torque in a static plasma

    NASA Astrophysics Data System (ADS)

    Hao, G. Z.; Liu, Y. Q.; Wang, A. K.; Xu, M.; Qu, H. P.; Peng, X. D.; Wang, Z. H.; Xu, J. Q.; Qiu, X. M.

    2014-01-01

    The MARS-F code [Y. Q. Liu et al., Phys. Plasmas 7, 3681 (2000)] is applied to numerically investigate the effect of the plasma pressure on the tearing mode stability as well as the tearing mode-induced electromagnetic torque, in the presence of a resistive wall. The tearing mode with a complex eigenvalue, resulted from the favorable averaged curvature effect [A. H. Glasser et al., Phys. Fluids 18, 875 (1975)], leads to a re-distribution of the electromagnetic torque with multiple peaking in the immediate vicinity of the resistive layer. The multiple peaking is often caused by the sound wave resonances. In the presence of a resistive wall surrounding the plasma, a rotating tearing mode can generate a finite net electromagnetic torque acting on the static plasma column. Meanwhile, an equal but opposite torque is generated in the resistive wall, thus conserving the total momentum of the whole plasma-wall system. The direction of the net torque on the plasma is always opposite to the real frequency of the mode, agreeing with the analytic result by Pustovitov [Nucl. Fusion 47, 1583 (2007)]. When the wall time is close to the oscillating time of the tearing mode, the finite net torque reaches its maximum. Without wall or with an ideal wall, no net torque on the static plasma is generated by the tearing mode. However, re-distribution of the torque density in the resistive layer still occurs.

  8. Resistive wall tearing mode generated finite net electromagnetic torque in a static plasma

    SciTech Connect

    Hao, G. Z. Wang, A. K.; Xu, M.; Qu, H. P.; Peng, X. D.; Wang, Z. H.; Xu, J. Q.; Qiu, X. M.; Liu, Y. Q.

    2014-01-15

    The MARS-F code [Y. Q. Liu et al., Phys. Plasmas 7, 3681 (2000)] is applied to numerically investigate the effect of the plasma pressure on the tearing mode stability as well as the tearing mode-induced electromagnetic torque, in the presence of a resistive wall. The tearing mode with a complex eigenvalue, resulted from the favorable averaged curvature effect [A. H. Glasser et al., Phys. Fluids 18, 875 (1975)], leads to a re-distribution of the electromagnetic torque with multiple peaking in the immediate vicinity of the resistive layer. The multiple peaking is often caused by the sound wave resonances. In the presence of a resistive wall surrounding the plasma, a rotating tearing mode can generate a finite net electromagnetic torque acting on the static plasma column. Meanwhile, an equal but opposite torque is generated in the resistive wall, thus conserving the total momentum of the whole plasma-wall system. The direction of the net torque on the plasma is always opposite to the real frequency of the mode, agreeing with the analytic result by Pustovitov [Nucl. Fusion 47, 1583 (2007)]. When the wall time is close to the oscillating time of the tearing mode, the finite net torque reaches its maximum. Without wall or with an ideal wall, no net torque on the static plasma is generated by the tearing mode. However, re-distribution of the torque density in the resistive layer still occurs.

  9. Rhythm generation, coordination, and initiation in the vocal pathways of male African clawed frogs.

    PubMed

    Yamaguchi, Ayako; Cavin Barnes, Jessica; Appleby, Todd

    2017-01-01

    Central pattern generators (CPGs) in the brain stem are considered to underlie vocalizations in many vertebrate species, but the detailed mechanisms underlying how motor rhythms are generated, coordinated, and initiated remain unclear. We addressed these issues using isolated brain preparations of Xenopus laevis from which fictive vocalizations can be elicited. Advertisement calls of male X. laevis that consist of fast and slow trills are generated by vocal CPGs contained in the brain stem. Brain stem central vocal pathways consist of a premotor nucleus [dorsal tegmental area of medulla (DTAM)] and a laryngeal motor nucleus [a homologue of nucleus ambiguus (n.IX-X)] with extensive reciprocal connections between the nuclei. In addition, DTAM receives descending inputs from the extended amygdala. We found that unilateral transection of the projections between DTAM and n.IX-X eliminated premotor fictive fast trill patterns but did not affect fictive slow trills, suggesting that the fast and slow trill CPGs are distinct; the slow trill CPG is contained in n.IX-X, and the fast trill CPG spans DTAM and n.IX-X. Midline transections that eliminated the anterior, posterior, or both commissures caused no change in the temporal structure of fictive calls, but bilateral synchrony was lost, indicating that the vocal CPGs are contained in the lateral halves of the brain stem and that the commissures synchronize the two oscillators. Furthermore, the elimination of the inputs from extended amygdala to DTAM, in addition to the anterior commissure, resulted in autonomous initiation of fictive fast but not slow trills by each hemibrain stem, indicating that the extended amygdala provides a bilateral signal to initiate fast trills.

  10. Smooth and flat phase-locked Kerr frequency comb generation by higher order mode suppression.

    PubMed

    Huang, S-W; Liu, H; Yang, J; Yu, M; Kwong, D-L; Wong, C W

    2016-05-16

    High-Q microresonator is perceived as a promising platform for optical frequency comb generation, via dissipative soliton formation. In order to achieve a higher quality factor and obtain the necessary anomalous dispersion, multi-mode waveguides were previously implemented in Si3N4 microresonators. However, coupling between different transverse mode families in multi-mode waveguides results in periodic disruption of dispersion and quality factor, and consequently causes perturbation to dissipative soliton formation and amplitude modulation to the corresponding spectrum. Careful choice of pump wavelength to avoid the mode crossing region is thus critical in conventional Si3N4 microresonators. Here, we report a novel design of Si3N4 microresonator in which single-mode operation, high quality factor, and anomalous dispersion are attained simultaneously. The novel microresonator is consisted of uniform single-mode waveguides in the semi-circle region, to eliminate bending induced mode coupling, and adiabatically tapered waveguides in the straight region, to avoid excitation of higher order modes. The intrinsic quality factor of the microresonator reaches 1.36 × 10(6) while the group velocity dispersion remains to be anomalous at -50 fs(2)/mm. With this novel microresonator, we demonstrate that broadband phase-locked Kerr frequency combs with flat and smooth spectra can be generated by pumping at any resonances in the optical C-band.

  11. Smooth and flat phase-locked Kerr frequency comb generation by higher order mode suppression

    PubMed Central

    Huang, S.-W.; Liu, H.; Yang, J.; Yu, M.; Kwong, D.-L.; Wong, C. W.

    2016-01-01

    High-Q microresonator is perceived as a promising platform for optical frequency comb generation, via dissipative soliton formation. In order to achieve a higher quality factor and obtain the necessary anomalous dispersion, multi-mode waveguides were previously implemented in Si3N4 microresonators. However, coupling between different transverse mode families in multi-mode waveguides results in periodic disruption of dispersion and quality factor, and consequently causes perturbation to dissipative soliton formation and amplitude modulation to the corresponding spectrum. Careful choice of pump wavelength to avoid the mode crossing region is thus critical in conventional Si3N4 microresonators. Here, we report a novel design of Si3N4 microresonator in which single-mode operation, high quality factor, and anomalous dispersion are attained simultaneously. The novel microresonator is consisted of uniform single-mode waveguides in the semi-circle region, to eliminate bending induced mode coupling, and adiabatically tapered waveguides in the straight region, to avoid excitation of higher order modes. The intrinsic quality factor of the microresonator reaches 1.36 × 106 while the group velocity dispersion remains to be anomalous at −50 fs2/mm. With this novel microresonator, we demonstrate that broadband phase-locked Kerr frequency combs with flat and smooth spectra can be generated by pumping at any resonances in the optical C-band. PMID:27181420

  12. Coordinated control of wind generation and energy storage for power system frequency regulation

    NASA Astrophysics Data System (ADS)

    Baone, Chaitanya Ashok

    Large-scale centralized synchronous generators have long been the primary actors in exercising active power and frequency control, and much of the existing grid control framework is predicated upon their dynamic terminal characteristics. Important among these characteristics is the inertia of such generators. These play key roles in determining the electromechanical stability of the electric power grid. Modern wind generator systems are partially or fully connected to the grid through power electronic interfaces, and hence do not present the same level of inertial coupling. The absence of inertial frequency response from modern wind generator systems is a topic of growing concern in power engineering practice, as the penetration of wind generation is expected to grow dramatically in the next few years. Solutions proposed in the literature have sought to address this problem by seeking to mimic the inherent inertial response characteristics of traditional synchronous generators via control loops added to wind generators. Recent literature has raised concerns regarding this approach, and the work here will further examine its shortcomings, motivating approaches that seek to optimally design for the characteristics of the equipment exercising the control, rather than forcing new technologies to mimic the characteristics of synchronous machines. In particular, this work will develop a new approach to power system frequency regulation, with features suited to distributed energy storage devices such as grid-scale batteries and wind turbine speed and blade pitch control. The dynamic characteristics of these new technologies are treated along with existing mechanisms, such as synchronous machine governor control, to develop a comprehensive multi-input control design approach. To make the method practically feasible for geographically distributed power systems, an observer-based distributed control design utilizing phasor measurement unit (PMU) signals along with local

  13. Mechanisms of Left-Right Coordination in Mammalian Locomotor Pattern Generation Circuits: A Mathematical Modeling View

    PubMed Central

    Talpalar, Adolfo E.; Rybak, Ilya A.

    2015-01-01

    The locomotor gait in limbed animals is defined by the left-right leg coordination and locomotor speed. Coordination between left and right neural activities in the spinal cord controlling left and right legs is provided by commissural interneurons (CINs). Several CIN types have been genetically identified, including the excitatory V3 and excitatory and inhibitory V0 types. Recent studies demonstrated that genetic elimination of all V0 CINs caused switching from a normal left-right alternating activity to a left-right synchronized “hopping” pattern. Furthermore, ablation of only the inhibitory V0 CINs (V0D subtype) resulted in a lack of left-right alternation at low locomotor frequencies and retaining this alternation at high frequencies, whereas selective ablation of the excitatory V0 neurons (V0V subtype) maintained the left–right alternation at low frequencies and switched to a hopping pattern at high frequencies. To analyze these findings, we developed a simplified mathematical model of neural circuits consisting of four pacemaker neurons representing left and right, flexor and extensor rhythm-generating centers interacting via commissural pathways representing V3, V0D, and V0V CINs. The locomotor frequency was controlled by a parameter defining the excitation of neurons and commissural pathways mimicking the effects of N-methyl-D-aspartate on locomotor frequency in isolated rodent spinal cord preparations. The model demonstrated a typical left-right alternating pattern under control conditions, switching to a hopping activity at any frequency after removing both V0 connections, a synchronized pattern at low frequencies with alternation at high frequencies after removing only V0D connections, and an alternating pattern at low frequencies with hopping at high frequencies after removing only V0V connections. We used bifurcation theory and fast-slow decomposition methods to analyze network behavior in the above regimes and transitions between them. The model

  14. Mechanisms of left-right coordination in mammalian locomotor pattern generation circuits: a mathematical modeling view.

    PubMed

    Molkov, Yaroslav I; Bacak, Bartholomew J; Talpalar, Adolfo E; Rybak, Ilya A

    2015-05-01

    The locomotor gait in limbed animals is defined by the left-right leg coordination and locomotor speed. Coordination between left and right neural activities in the spinal cord controlling left and right legs is provided by commissural interneurons (CINs). Several CIN types have been genetically identified, including the excitatory V3 and excitatory and inhibitory V0 types. Recent studies demonstrated that genetic elimination of all V0 CINs caused switching from a normal left-right alternating activity to a left-right synchronized "hopping" pattern. Furthermore, ablation of only the inhibitory V0 CINs (V0D subtype) resulted in a lack of left-right alternation at low locomotor frequencies and retaining this alternation at high frequencies, whereas selective ablation of the excitatory V0 neurons (V0V subtype) maintained the left-right alternation at low frequencies and switched to a hopping pattern at high frequencies. To analyze these findings, we developed a simplified mathematical model of neural circuits consisting of four pacemaker neurons representing left and right, flexor and extensor rhythm-generating centers interacting via commissural pathways representing V3, V0D, and V0V CINs. The locomotor frequency was controlled by a parameter defining the excitation of neurons and commissural pathways mimicking the effects of N-methyl-D-aspartate on locomotor frequency in isolated rodent spinal cord preparations. The model demonstrated a typical left-right alternating pattern under control conditions, switching to a hopping activity at any frequency after removing both V0 connections, a synchronized pattern at low frequencies with alternation at high frequencies after removing only V0D connections, and an alternating pattern at low frequencies with hopping at high frequencies after removing only V0V connections. We used bifurcation theory and fast-slow decomposition methods to analyze network behavior in the above regimes and transitions between them. The model

  15. Efficient frequency generation in phoXonic cavities based on hollow whispering gallery mode resonators

    PubMed Central

    Farnesi, Daniele; Righini, Giancarlo; Nunzi Conti, Gualtiero; Soria, Silvia

    2017-01-01

    We report on nonlinear optical effects on phoxonic cavities based on hollow whispering gallery mode resonators pumped with a continuous wave laser. We observed stimulated scattering effects such as Brillouin and Raman, Kerr effects such as degenerated and non-degenerated four wave mixing, and dispersive wave generation. These effects happened concomitantly. Hollow resonators give rise to a very rich nonlinear scenario due to the coexistence of several family modes. PMID:28266641

  16. Next Generation Large Mode Area Fiber Technologies for High Power Fiber Laser Arrays

    DTIC Science & Technology

    2012-06-08

    REPORT Next Generation Large Mode Area Fiber Technologies for High Power Fiber Laser Arrays 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: This program...monolithically-integrated building blocks (individual laser channels) of high power beam-combined fiber laser arrays. Robust single-mode performance...of CCC fibers with core sizes of up to ~60?m has been rigorously demonstrated. Various CCC fiber based high power lasers have been also

  17. Stable Gait Generation of a Quasi-Passive Biped Walking Robot Based on Mode Decomposition

    NASA Astrophysics Data System (ADS)

    Matsumoto, Itaru

    A passive walker is a robot which can walk down a shallow slope without active control or energy input, being powered only by gravity. This paper proposes a control law that can stabilize the gait of a quasi-passive walker by manipulating torque at the hip joint. The motion of the quasi-passive walker is divided into two modes: one is a sinusoidal mode and the other a hyperbolic sinusoidal mode. The controller is designed with a servo system which forces the motion of the sinusoidal mode to track the reference input signal obtained from the phase-plane trajectory of the hyperbolic sinusoidal mode. The generated gait is quite natural, because the input of the servo system is made based on the system dynamics. The results of simulations have demonstrated the effectiveness of the proposed control law.

  18. The NASA Community Coordinated Modeling Center (CCMC) Next Generation Space Weather Data Warehouse

    NASA Astrophysics Data System (ADS)

    Maddox, M. M.; Kuznetsova, M. M.; Pulkkinen, A. A.; Zheng, Y.; Rastaetter, L.; Chulaki, A.; Pembroke, A. D.; Wiegand, C.; Mullinix, R.; Boblitt, J.; Mendoza, A. M. M.; Swindell, M. J., IV; Bakshi, S. S.; Mays, M. L.; Shim, J. S.; Hesse, M.; Collado-Vega, Y. M.; Taktakishvili, A.; MacNeice, P. J.

    2014-12-01

    The Community Coordinated Modeling Center (CCMC) at NASA Goddard Space Flight Center enables, supports, and performs research and development for next generation space science and space weather models. The CCMC currently hosts a large and expanding collection of state-or-the-art, physics-based space weather models that have been developed by the international research community. There are many tools and services provided by the CCMC that are currently available world-wide, along with the ongoing development of new innovative systems and software for research, discovery, validation, visualization, and forecasting. Over the history of the CCMC's existence, there has been one constant engineering challenge - describing, managing, and disseminating data. To address the challenges that accompany an ever-expanding number of models to support, along with a growing catalog of simulation output - the CCMC is currently developing a flexible and extensible space weather data warehouse to support both internal and external systems and applications. This paper intends to chronicle the evolution and future of the CCMC's data infrastructure, and the current infrastructure re-engineering activities that seek to leverage existing community data model standards like SPASE and the IMPEx Simulation Data Model.

  19. A new electromagnetic acoustic transducer design for generating torsional guided wave modes for pipe inspections

    NASA Astrophysics Data System (ADS)

    Hill, Samuel; Dixon, Steve; Sri Harsha Reddy, K.; Rajagopal, Prabhu; Balasubramaniam, Krishnan

    2017-02-01

    Guided waves inspection is a well-established method for the long-range ultrasonic inspection of pipes. Guided waves, used in a pulse-echo arrangement, can inspect a large range of the pipe from a single point as the pipe structure carries the waves over a large distance due to the relatively low attenuation of the wave modes. However, the complexity of the dispersion characteristics of these pipe guided wave modes are well known, and can lead to diffculty interpreting the obtained results. The torsional family of guided wave modes are generally considered to have much simpler dispersion characteristics; especially the fundamental T(0,1) mode, which is nominally non-dispersive, making it particularly useful for guided wave inspection. Torsional waves have been generated by a circumferential ring of transducers to approximate an axi-symmetric load to excite this T(0, 1) mode. Presented here is a new design of Electromagnetic Acoustic Transducer (EMAT) that can generate a T(0, 1) as a single transducer, rather than a circumferential array of transducers that all need to be excited in order to generate an axisymmetric force. The EMAT consists of a periodic permanent magnet array and a single meander coil, meaning that the excitation of the torsional mode is greatly simplified. The design parameters of this new EMAT are explored, and the ability to detect notch defects on a pipe is demonstrated.

  20. Diode-pumped Kerr-lens mode-locked Yb: GSO laser generating 72 fs pulses

    NASA Astrophysics Data System (ADS)

    Tian, Wenlong; Wang, Zhaohua; Zhu, Jiangfeng; Zheng, Lihe; Xu, Xiaodong; Xu, Jun; Wei, Zhiyi

    2016-05-01

    The generation of 72 fs hyperbolic secant pulses centered at 1050 nm with 17.8 nm bandwidth from a diode pumped Kerr-lens mode-locked Yb: GSO laser is demonstrated. With the help of a semiconductor saturable absorber mirror, stable mode-locking with an average output power of 85 mW at a repetition rate of 113 MHz is realized. To the best of our knowledge, this is the first demonstration of Kerr-lens mode-locking in Yb: GSO laser.

  1. Diode-pumped mode-locked Yb:YCOB laser generating 35 fs pulses.

    PubMed

    Yoshida, Akira; Schmidt, Andreas; Petrov, Valentin; Fiebig, Christian; Erbert, Götz; Liu, Junhai; Zhang, Huaijin; Wang, Jiyang; Griebner, Uwe

    2011-11-15

    Direct sub-50-fs pulse generation is demonstrated with a mode-locked Yb:YCa4O(BO3)3 laser. With external compression, pulses as short as 35 fs are generated at 1055 nm. The oscillator operating at a repetition rate of 95 MHz is pumped by a two-section distributed Bragg reflector tapered diode laser and mode locked by a semiconductor saturable absorber mirror. The onset of self-Raman-conversion for pulse spectral bandwidths exceeding 40 nm (FWHM) is observed.

  2. Spatiotemporal Lugiato-Lefever formalism for Kerr-comb generation in whispering-gallery-mode resonators

    NASA Astrophysics Data System (ADS)

    Chembo, Yanne K.; Menyuk, Curtis R.

    2013-05-01

    We demonstrate that frequency (Kerr) comb generation in whispering-gallery-mode resonators can be modeled by a variant of the Lugiato-Lefever equation that includes higher-order dispersion and nonlinearity. This spatiotemporal model allows us to explore pulse formation in which a large number of modes interact cooperatively. Pulse formation is shown to play a critical role in comb generation, and we find conditions under which single pulses (dissipative solitons) and multiple pulses (rolls) form. We show that a broadband comb is the spectral signature of a dissipative soliton, and we also show that these solitons can be obtained by using a weak anomalous dispersion and subcritical pumping.

  3. Investigation of a fast transition from pump mode to generating mode in a model scale reversible pump turbine

    NASA Astrophysics Data System (ADS)

    Stens, C.; Riedelbauch, S.

    2016-11-01

    Pumped storage power plants are an efficient way to store energy at a large scale. In the last years, the changes between pump and turbine mode have become more and more frequent and the necessity of fast changes has increased. This paper analyses the flow in a model scale pump turbine during a fast transition from pump mode to generating mode by means of CFD. Results will be compared between two different mesh sizes and between simulation and measurement. A linear variation of rotational speed over time is chosen. A time-dependent flow rate through the machine is prescribed at the inlet. Due to the varying conditions, a fully transient analysis is carried out using the open-source code OpenFOAM®. The state of the machine at certain points of time during the transient is compared to the results for steady state simulations with identical boundary conditions. To characterize the phenomena in the guide vane channels, torque on selected guide vanes is evaluated as well as pressure at predefined locations. In the runner, pressure sensors are evaluated near the leading edge on pressure and suction side. In the draft tube, four dynamic pressure sensors in a plane below the runner are analysed. Frequencies and amplitudes are compared to simulation.

  4. Generation of polarisation-nonuniform modes in a high-power CO{sub 2} laser

    SciTech Connect

    Niz'ev, Vladimir G; Yakunin, V P; Turkin, N G

    2009-06-30

    A method describing radially and azimuthally polarised laser modes is presented, which is devoid of intrinsic contradictions and unjustified restrictions. The solutions of the wave equation found in the paper satisfy Maxwell's equation bigtriangledownE = 0. This allowed the calculation of all the components of the fields of such modes, including the longitudinal one. Expressions for tight focusing of radially and azimuthally polarised modes are obtained in the Debye approximation. The methods of intracavity generation of such modes in a high-power industrial CO{sub 2} laser are experimentally realised and methods of mutual transformation of these modes outside the cavity are developed. The intracavity generation of azimuthally polarised modes was achieved by using as a rear highly reflecting mirror either V-shaped axicons or metal diffraction mirrors with the relief period comparable to the wavelength. Radially polarised radiation was generated by using diffraction mirrors with the relief period of the order of two wavelengths. The polarisation-nonuniform TEM{sub 01*} and TEM{sub 11*} modes of power up to 1.8 kW are generated for the first time. In this case, the degree of polarisation was close to 100% within the entire radiation power range both in the near- and far-field zones. By using two half-wave phase shifters, the azimuthally polarised radiation is transformed to radially polarised radiation and vice versa, the energy efficiency of this transformation being 92%. These results open up the possibility for industrial applications of such radiation. (control of laser radiation parameters)

  5. Inhibitory Response Capacities of Bilateral Lower and Upper Extremities in Children with Developmental Coordination Disorder in Endogenous and Exogenous Orienting Modes

    ERIC Educational Resources Information Center

    Tsai, Chia-Liang; Yu, Yi-Kai; Chen, Yung-Jung; Wu, Sheng-Kuang

    2009-01-01

    This study was designed to investigate separately the inhibitory response capacity and the lateralization effect in children with developmental coordination disorder (DCD) in the endogenous and exogenous modes of orienting attention. Children with DCD on the lower extremities (DCD-LEs), along with age-matched controls, completed four tasks that…

  6. Metal-ion effects on the polarization of metal-bound water and infrared vibrational modes of the coordinated metal center of Mycobacterium tuberculosis pyrazinamidase via quantum mechanical calculations.

    PubMed

    Salazar-Salinas, Karim; Baldera-Aguayo, Pedro A; Encomendero-Risco, Jimy J; Orihuela, Melvin; Sheen, Patricia; Seminario, Jorge M; Zimic, Mirko

    2014-08-28

    Mycobacterium tuberculosis pyrazinamidase (PZAse) is a key enzyme to activate the pro-drug pyrazinamide (PZA). PZAse is a metalloenzyme that coordinates in vitro different divalent metal cofactors in the metal coordination site (MCS). Several metals including Co(2+), Mn(2+), and Zn(2+) are able to reactivate the metal-depleted PZAse in vitro. We use quantum mechanical calculations to investigate the Zn(2+), Fe(2+), and Mn(2+) metal cofactor effects on the local MCS structure, metal-ligand or metal-residue binding energy, and charge distribution. Results suggest that the major metal-dependent changes occur in the metal-ligand binding energy and charge distribution. Zn(2+) shows the highest binding energy to the ligands (residues). In addition, Zn(2+) and Mn(2+) within the PZAse MCS highly polarize the O-H bond of coordinated water molecules in comparison with Fe(2+). This suggests that the coordination of Zn(2+) or Mn(2+) to the PZAse protein facilitates the deprotonation of coordinated water to generate a nucleophile for catalysis as in carboxypeptidase A. Because metal ion binding is relevant to enzymatic reaction, identification of the metal binding event is important. The infrared vibrational mode shift of the C═Nε (His) bond from the M. tuberculosis MCS is the best IR probe to metal complexation.

  7. Low-frequency ultrasonic Bessel-like collimated beam generation from radial modes of piezoelectric transducers

    NASA Astrophysics Data System (ADS)

    Chillara, Vamshi Krishna; Pantea, Cristian; Sinha, Dipen N.

    2017-02-01

    We present a very simple approach to generate a collimated ultrasonic beam that exploits the natural Bessel-like vibration pattern of the radial modes of a piezoelectric disc with lateral clamping. This eliminates the need for the conventional annular Bessel pattern of the electrodes with individual electrode excitation on the piezo-disc, thus simplifying the transducer design. Numerical and experimental studies are carried out to investigate the Bessel-like vibration patterns of these radial modes showing an excellent agreement between these two studies. Measured ultrasonic beam-profiles in water from the radial modes confirm the profile to be a Bessel beam. Collimated beam generation from radial modes is investigated using a coupled electromechanical finite-element model. It is found that clamping the lateral edges of piezoelectric transducers results in a high-degree of collimation with practically no side-lobes similar to a parametric array beam. Ultrasonic beam-profile measurements in water with both free and clamped piezoelectric transducer are presented. The collimated beam generation using the present technique of using the laterally clamped radial modes finds significant applications in low-frequency imaging through highly attenuating materials.

  8. Formation and characterization of the vortices generated by a DBD plasma actuator in burst mode

    NASA Astrophysics Data System (ADS)

    Mishra, Bal Krishan; Panigrahi, P. K.

    2017-02-01

    The present study reports the formation and evolution characteristics of the continuously generated vortical structure and resulting flow field in quiescent air induced by a dielectric-barrier-discharge (DBD) plasma actuator in burst mode operation. A starting vortex is formed during the initial actuation period, which disappears after a small time interval for continuous mode operation of the DBD plasma actuator. A burst input signal to the actuator generates a train of self-similar vortices. The behaviour of vortices and the average flow field induced by the actuator has been studied using high speed schlieren visualization and particle image velocimetry technique for different actuation amplitude and duty cycle parameters. These repeating vortices travel faster than the starting vortex, and the vortex core velocity of these repeating vortices increases with increase in duty cycle parameter. Fuller u-velocity profile, higher v-velocity near the edge of the outer shear layer region, and higher growth of the wall jet thickness is observed due to enhanced entrainment by repeating vortices for burst mode operation. The repeating vortices travel at an angle of 21° relative to the wall surface for duty cycle parameter of 90.9% in comparison to 31° for the starting vortex. Self-similarity of the velocity profile is delayed in the streamwise direction for burst mode operation in comparison to that for the continuous mode of operation. This can be attributed to delay in attaining the maximum velocity of the wall jet profile and presence of coherent structures for the burst mode operation. The non-dimensional vortex core location and size for repeating vortices follow power law fit similar to the starting vortex with difference in value of the power law exponent. The phase difference between the input voltage and current drawn is in the range of π/12 to π/9 (in radians) for both continuous and burst mode operation indicating identical electrical behaviour of the

  9. ERK and phosphoinositide 3-kinase temporally coordinate different modes of actin-based motility during embryonic wound healing.

    PubMed

    Li, Jingjing; Zhang, Siwei; Soto, Ximena; Woolner, Sarah; Amaya, Enrique

    2013-11-01

    Embryonic wound healing provides a perfect example of efficient recovery of tissue integrity and homeostasis, which is vital for survival. Tissue movement in embryonic wound healing requires two functionally distinct actin structures: a contractile actomyosin cable and actin protrusions at the leading edge. Here, we report that the discrete formation and function of these two structures is achieved by the temporal segregation of two intracellular upstream signals and distinct downstream targets. The sequential activation of ERK and phosphoinositide 3-kinase (PI3K) signalling divides Xenopus embryonic wound healing into two phases. In the first phase, activated ERK suppresses PI3K activity, and is responsible for the activation of Rho and myosin-2, which drives actomyosin cable formation and constriction. The second phase is dominated by restored PI3K signalling, which enhances Rac and Cdc42 activity, leading to the formation of actin protrusions that drive migration and zippering. These findings reveal a new mechanism for coordinating different modes of actin-based motility in a complex tissue setting, namely embryonic wound healing.

  10. Versatile bonding and coordination modes of ditriazolylidene ligands in rhodium(iii) and iridium(iii) complexes.

    PubMed

    Farrell, Kevin; Müller-Bunz, Helge; Albrecht, Martin

    2016-10-12

    Metalation of novel ditriazolium salts containing a trimethylene (-CH2CH2CH2-) or dimethylether linker (-CH2OCH2-) was probed with different rhodium(iii) and iridium(iii) precursors. When using [MCp*Cl2]2, a transmetalation protocol via a triazolylidene silver intermediate was effective, while base-assisted metalation with MCl3via sequential deprotonation of the triazolium salt with KOtBu and addition of the metal precursor afforded homoleptic complexes. The N-substituent on the triazole heterocycle directed the metalation process and led to Ctrz,Ctrz,CPh-tridentate chelating ditriazolylidene complexes for N-phenyl substituents. With ethyl substituents, only Ctrz,Ctrz-bidentate complexes were formed, while metalation with mesityl substituents was unsuccessful, presumably due to steric constraints. Through modification of the reaction conditions for the metalation step, an intermediate species was isolated that contains a Ctrz,CPh-bidentate chelate en route to the formation of the tridentate ligand system. Accordingly, Cphenyl-H bond activation occurs prior to formation of the second metal-triazolylidene bond. Stability studies with a Ctrz,Ctrz,CPh-tridentate chelating ditriazolylidene iridium complex towards DCl showed deuterium incorporation at both N-phenyl groups and indicate that Cphenyl-H bond activation is reversible while the Ctrz-Ir bond is robust. The flexible linker between the two triazolylidene donor sites provides access to both facial and meridional coordination modes.

  11. Generation of entangled TEM01 modes with periodically poled KTiOPO4 crystal

    NASA Astrophysics Data System (ADS)

    Rong-Guo, Yang; Jing-jing, Wang; Jing, Zhang; Heng-Xin, Sun

    2016-07-01

    Spatial quantum optics based on the high-order transverse mode is important for the super-resolution measurement and quantum image beyond the shot noise level. Quantum entanglement of the transverse plane Hermite-Gauss TEM01 mode has been demonstrated experimentally in this paper. Two squeezed TEM01 modes, which are generated by a pair of degenerate optical parametric amplifiers (DOPA) with the nonlinear crystals of periodically poled KTiOPO4, have been combined to produce TEM01 mode entanglement using a beam splitter. The 1.5 dB for the sum of amplitude and 1.2 dB for the difference of phase below shot-noise level is achieved with the measurement system of a Bell state detection. Project supported by the National Natural Science Foundation of China (Grant Nos. 11504218 and 61108003) and the Natural Science Foundation of Shanxi Province, China (Grant No. 2013021005-2).

  12. Role of antenna modes and field enhancement in second harmonic generation from dipole nanoantennas.

    PubMed

    de Ceglia, Domenico; Vincenti, Maria Antonietta; De Angelis, Costantino; Locatelli, Andrea; Haus, Joseph W; Scalora, Michael

    2015-01-26

    We study optical second harmonic generation from metallic dipole antennas with narrow gaps. Enhancement of the fundamental-frequency field in the gap region plays a marginal role on conversion efficiency. In the symmetric configuration, i.e., with the gap located at the center of the antenna axis, reducing gap size induces a significant red-shift of the maximum conversion efficiency peak. Either enhancement or inhibition of second-harmonic emission may be observed as gap size is decreased, depending on the antenna mode excited at the harmonic frequency. The second-harmonic signal is extremely sensitive to the asymmetry introduced by gap's displacements with respect to the antenna center. In this situation, second-harmonic light can couple to all the available antenna modes. We perform a multipolar analysis that allows engineering the far-field SH emission and find that the interaction with quasi-odd-symmetry modes generates radiation patterns with a strong dipolar component.

  13. Incremental N-mode SVD for large-scale multilinear generative models.

    PubMed

    Lee, Minsik; Choi, Chong-Ho

    2014-10-01

    Tensor decomposition is frequently used in image processing and machine learning for its ability to express higher order characteristics of data. Among tensor decomposition methods, N-mode singular value decomposition (SVD) is widely used owing to its simplicity. However, the data dimension often becomes too large to perform N-mode SVD directly due to memory limitation. An incremental method to N-mode SVD can be used to resolve this issue, but existing approaches only provide a result, which is just enough to solve discriminative problems, not the full factorization result. In this paper, we present a complete derivation of the incremental N-mode SVD, which can be applied to generative models, accompanied by a technique that can reduce the computational cost by reordering calculations. The proposed incremental N-mode SVD can also be used effectively to update the current result of N-mode SVD when new training data is received. The proposed method provides a very good approximation of N -mode SVD for the experimental data, and requires much less computation in updating a multilinear model.

  14. Generation of ordinary mode electromagnetic radiation near the upper hybrid frequency in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Ashour-Abdalla, M.; Okuda, H.

    1984-01-01

    It is shown by means of plasma numerical simulations that long-wavelength ordinary mode electromagnetic radiation can be generated from short-wavelength electrostatic waves near the upper hybrid resonance frequency in an inhomogeneous plasma. A possible relation of this process to nonthermal continuum radiation in the magnetosphere is discussed.

  15. Supercontinuum generation by noise-like pulses transmitted through normally dispersive standard single-mode fibers.

    PubMed

    Zaytsev, Alexey; Lin, Chih-Hsuan; You, Yi-Jing; Chung, Chia-Chun; Wang, Chi-Luen; Pan, Ci-Ling

    2013-07-01

    We report generation of broadband supercontinuum (SC) by noise-like pulses (NLPs) with a central wavelength of 1070 nm propagating through a long piece of standard single-mode fibers (~100 meters) in normal dispersion region far from the zero-dispersion point. Theoretical simulations indicate that the physical mechanism of SC generation is due to nonlinear effects in fibers. The cascaded Raman scattering is responsible for significant spectral broadening in the longer wavelength regions whereas the Kerr effect results in smoothing of SC generated spectrum. The SC exhibits low threshold (43 nJ) and a flat spectrum over 1050-1250 nm.

  16. pH-controlled coordination mode rearrangements of "clickable" Huisgen-based multidentate ligands with [M(I)(CO)3]+ (M = Re, (99m)Tc).

    PubMed

    Bottorff, Shalina C; Moore, Adam L; Wemple, Ariana R; Bučar, Dejan-Krešimir; MacGillivray, Leonard R; Benny, Paul D

    2013-03-18

    The viability of the Huisgen cycloaddition reaction for clickable radiopharmaceutical probes was explored with an alkyne-functionalized 2-[(pyridin-2-ylmethyl)amino]acetic acid (PMAA) ligand system, 3, and fac-[M(I)(OH2)3(CO)3](+) (M = Re, (99m)Tc). Two synthetic strategies, (1) click, then chelate and (2) chelate, then click, were investigated to determine the impact of assembly order on the reactivity of the system. In the click, then chelate approach, fac-[M(I)(OH2)3(CO)3](+) was reacted with the PMAA ligand "clicked" to the benzyl azide, 5, to yield two unique coordination species, fac-[M(I)(CO)3(O,N(amine),N(py)-5)], M = Re (8), (99m)Tc (8A), and fac-[M(I)(CO)3(N(tri),N(amine),N(py)-5)], M = Re (9), (99m)Tc (9A), where coordination is through the triazole (N(tri)), central amine (N(amine)), pyridine (N(py)), or carboxylate (O). Depending on the reaction pH, different ratios of complexes 8(A) and 9(A) were observed, but single species were obtained of (O,N(amine),N(py)) coordination, 8(A), in basic pHs (>9) and (N(tri),N(amine),N(py)) coordination, 9(A), in slightly acidic pHs (<4). In the chelate, then click approach, the (O,N(amine),N(py)) coordination of [M(I)(CO)3](+) was preorganized in the alkyne-functionalized fac-[M(I)(CO)3(O,N(amine),N(py)-3)], M = Re (6), (99m)Tc (6A), followed by standard Cu(I)-catalyzed Huisgen "click" conditions at pH ≈ 7.4, where the (O,N(amine),N(py)) coordination mode remained unchanged upon formation of the triazole product in the clicked molecule. Despite the slow substitution kinetics of the low-spin d(6) metal, the coordination modes (O,N(amine),N(py)) and (N(tri),N(amine),N(py)) were found to reversibly intraconvert between 8(A) and 9(A) based upon changes in pH that mirrored the (O,N(amine),N(py)) coordination in basic pHs and (N(tri),N(amine),N(py)) coordination in acidic pHs. Comparison of the Re and (99m)Tc analogs also revealed faster intraconversion between the coordination modes for (99m)Tc.

  17. High-order harmonic generation from polyatomic molecules including nuclear motion and a nuclear modes analysis

    SciTech Connect

    Madsen, C. B.; Abu-samha, M.; Madsen, L. B.

    2010-04-15

    We present a generic approach for treating the effect of nuclear motion in high-order harmonic generation from polyatomic molecules. Our procedure relies on a separation of nuclear and electron dynamics where we account for the electronic part using the Lewenstein model and nuclear motion enters as a nuclear correlation function. We express the nuclear correlation function in terms of Franck-Condon factors, which allows us to decompose nuclear motion into modes and identify the modes that are dominant in the high-order harmonic generation process. We show results for the isotopes CH{sub 4} and CD{sub 4} and thereby provide direct theoretical support for a recent experiment [S. Baker et al., Science 312, 424 (2006)] that uses high-order harmonic generation to probe the ultrafast structural nuclear rearrangement of ionized methane.

  18. Non-Gaussian isocurvature perturbations from Goldstone modes generated during inflation

    NASA Astrophysics Data System (ADS)

    Bucher, Martin; Zhu, Yong

    1997-06-01

    We investigate non-Gaussian isocurvature perturbations generated by the evolution of Goldstone modes during inflation. If a global symmetry is broken before inflation, the resulting Goldstone modes are disordered during inflation in a precise and predictable way. After inflation these Goldstone modes order themselves in a self-similar way, much as Goldstone modes in field ordering scenarios based on the Kibble mechanism. For (H2inf/M2Pl)~10-6, through their gravitational interaction these Goldstone modes generate density perturbations of approximately the right magnitude to explain the cosmic microwave background (CMB) anisotropy and seed the structure seen in the universe today. We point out that for the pattern of symmetry breaking in which a global U(1) is completely broken, the inflationary evolution of the Goldstone field may be treated as that of a massless scalar field. Unlike the more commonly discussed case in which a global U(1) is completely broken in a cosmological phase transition, in the inflationary case the production of defects can be made exponentially small, so that Goldstone field evolution is completely linear. In such a model non-Gaussian perturbations result because to lowest order density perturbations are sourced by products of Gaussian fields. Consequently, in this non-Gaussian model N-point correlations may be calculated by evaluating Feynman diagrams. We explore the issue of phase dispersion and conclude that this non-Gaussian model predicts Doppler peaks in the CMB anisotropy.

  19. Multiplexed Cassegrain Reflector Antenna for Simultaneous Generation of Three Orbital Angular Momentum (OAM) Modes

    NASA Astrophysics Data System (ADS)

    Byun, Woo Jin; Kim, Kwang Seon; Kim, Bong Su; Lee, Young Seung; Song, Myung Sun; Choi, Hyung Do; Cho, Yong Heui

    2016-06-01

    A multiplexed Cassegrain reflector antenna with a 2 × 2 open-ended rectangular waveguide (OERW) matrix feed and an orbital angular momentum (OAM) mode mux is proposed for the simultaneous generation of three OAM modes (l = 0, ±1). The OAM mode mux (OMM) was designed using sequential combinations of quadrature hybrids, crossovers, and phase shifters to multiplex and demultiplex three OAM modes at the same time. The 2 × 2 OERW matrix feed and the OMM were separately measured and their performances were verified according to proposed theories. A near-field antenna measurement for a multiplexed Cassegrain reflector antenna was conducted to obtain the far-field magnitude and phase patterns around polar elevation angle θ and azimuthal angle ϕ, thus confirming that our antenna can produce three OAM modes simultaneously. We also measured the communication link characteristics of two identical multiplexed antennas. The measurement results show that the channel isolation of three OAM modes is more than 12.7 [dB] and 17 [dB] for fixed and compensated receiver positions, respectively, indicating that the proposed antenna system can be used for independent communication links with the same frequency and polarisation.

  20. Multiplexed Cassegrain Reflector Antenna for Simultaneous Generation of Three Orbital Angular Momentum (OAM) Modes

    PubMed Central

    Byun, Woo Jin; Kim, Kwang Seon; Kim, Bong Su; Lee, Young Seung; Song, Myung Sun; Choi, Hyung Do; Cho, Yong Heui

    2016-01-01

    A multiplexed Cassegrain reflector antenna with a 2 × 2 open-ended rectangular waveguide (OERW) matrix feed and an orbital angular momentum (OAM) mode mux is proposed for the simultaneous generation of three OAM modes (l = 0, ±1). The OAM mode mux (OMM) was designed using sequential combinations of quadrature hybrids, crossovers, and phase shifters to multiplex and demultiplex three OAM modes at the same time. The 2 × 2 OERW matrix feed and the OMM were separately measured and their performances were verified according to proposed theories. A near-field antenna measurement for a multiplexed Cassegrain reflector antenna was conducted to obtain the far-field magnitude and phase patterns around polar elevation angle θ and azimuthal angle ϕ, thus confirming that our antenna can produce three OAM modes simultaneously. We also measured the communication link characteristics of two identical multiplexed antennas. The measurement results show that the channel isolation of three OAM modes is more than 12.7 [dB] and 17 [dB] for fixed and compensated receiver positions, respectively, indicating that the proposed antenna system can be used for independent communication links with the same frequency and polarisation. PMID:27252079

  1. Can a Fast-Mode EUV Wave Generate a Stationary Front?

    NASA Astrophysics Data System (ADS)

    Chen, P. F.; Fang, C.; Chandra, R.; Srivastava, A. K.

    2016-11-01

    The discovery of stationary "EIT waves" about 16 years ago posed a big challenge to the then favorite fast-mode wave model for coronal "EIT waves". It encouraged various non-wave models and played an important role in convergence of the opposing viewpoints toward the recent consensus that there are two types of EUV waves. However, it was recently discovered that a stationary wave front can also be generated when a fast-mode wave passes through a magnetic quasi-separatrix layer (QSL). In this article, we perform a magnetohydrodynamic (MHD) numerical simulation of the interaction between a fast-mode wave and a magnetic QSL, and a stationary wave front is reproduced. The analysis of the numerical results indicates that near the plasma beta {˜} 1 layer in front of the magnetic QSL, part of the fast-mode wave is converted to a slow-mode MHD wave, which is then trapped inside the magnetic loops, forming a stationary wave front. Our results imply that we have to be cautious in identifying the nature of a wave, since there may be mode conversion during the propagation of the waves driven by solar eruptions.

  2. Multiplexed Cassegrain Reflector Antenna for Simultaneous Generation of Three Orbital Angular Momentum (OAM) Modes.

    PubMed

    Byun, Woo Jin; Kim, Kwang Seon; Kim, Bong Su; Lee, Young Seung; Song, Myung Sun; Choi, Hyung Do; Cho, Yong Heui

    2016-06-02

    A multiplexed Cassegrain reflector antenna with a 2 × 2 open-ended rectangular waveguide (OERW) matrix feed and an orbital angular momentum (OAM) mode mux is proposed for the simultaneous generation of three OAM modes (l = 0, ±1). The OAM mode mux (OMM) was designed using sequential combinations of quadrature hybrids, crossovers, and phase shifters to multiplex and demultiplex three OAM modes at the same time. The 2 × 2 OERW matrix feed and the OMM were separately measured and their performances were verified according to proposed theories. A near-field antenna measurement for a multiplexed Cassegrain reflector antenna was conducted to obtain the far-field magnitude and phase patterns around polar elevation angle θ and azimuthal angle ϕ, thus confirming that our antenna can produce three OAM modes simultaneously. We also measured the communication link characteristics of two identical multiplexed antennas. The measurement results show that the channel isolation of three OAM modes is more than 12.7 [dB] and 17 [dB] for fixed and compensated receiver positions, respectively, indicating that the proposed antenna system can be used for independent communication links with the same frequency and polarisation.

  3. Model-OA wind turbine generator - Failure modes and effects analysis

    NASA Technical Reports Server (NTRS)

    Klein, William E.; Lali, Vincent R.

    1990-01-01

    The results failure modes and effects analysis (FMEA) conducted for wind-turbine generators are presented. The FMEA was performed for the functional modes of each system, subsystem, or component. The single-point failures were eliminated for most of the systems. The blade system was the only exception. The qualitative probability of a blade separating was estimated at level D-remote. Many changes were made to the hardware as a result of this analysis. The most significant change was the addition of the safety system. Operational experience and need to improve machine availability have resulted in subsequent changes to the various systems, which are also reflected in this FMEA.

  4. Spectral features of anti-Stokes and Stokes modes generated by stimulated Raman scattering in liquid toluene

    NASA Astrophysics Data System (ADS)

    Yadav, Suchita; Kumar, Govind; Vijaya, R.

    2016-10-01

    Stimulated Raman scattering leading to the generation of four first-order Stokes modes at shifts of 862.9, 1035, 2967 and 3086 cm-1, one second-order Stokes mode at a shift of 2032.5 cm-1 and one first-order anti-Stokes mode at a shift of 946.3 cm-1 has been measured in an experiment using liquid toluene. The observed shifts are assigned to the earlier reported Raman shifts of toluene at 786, 1006, 2979, 3060 cm-1 due to ring-breathing mode, ring deformation mode, CH3 stretching mode and CH stretching mode, respectively. Simultaneous measurement of all the Raman modes, including the second-order Stokes and first-order anti-Stokes, and their correct assignment to the vibrational modes of toluene is not reported widely in earlier work. The Raman modes generated from toluene emerge as concentric rings of different diameters. The phase-matching angle for anti-Stokes generation is thus measured and compared with the expected value from calculation. The spectral broadening observed near two of the modes is explained with the help of Raman-active modes of toluene reported earlier by others. Raman shifts, threshold levels, gain and beam profile of all the modes, along with the phase matching of the anti-Stokes mode, are reported.

  5. Rhodium nanocatalysts stabilized by various bipyridine ligands in nonaqueous ionic liquids: influence of the bipyridine coordination modes in arene catalytic hydrogenation.

    PubMed

    Léger, Bastien; Denicourt-Nowicki, Audrey; Olivier-Bourbigou, Hélène; Roucoux, Alain

    2008-10-06

    Rhodium nanoparticles stabilized by 2,2'-, 3,3'-, 4,4'-bipyridine ligands were prepared in various ionic liquids according to a chemical reduction approach. Zerovalent nanospecies in the size range of 2.0-2.5 nm were characterized. The nature of the bipyridine and its influence on the coordination environment of rhodium nanoparticles were investigated in various nonaqueous ionic liquids according to the cation and anion. The hydrogenation of various aromatic compounds by these colloidal suspensions was carried out at 80 degrees C and under 40 bar of H 2. A first structural explanation based on bipyridine coordination modes is proposed to justify the observed different activities.

  6. Out-of-Plane Coordinated Porphyrin Nanotubes with Enhanced Singlet Oxygen Generation Efficiency

    NASA Astrophysics Data System (ADS)

    Zhao, Qiang; Wang, Yao; Xu, Yanshuang; Yan, Yun; Huang, Jianbin

    2016-08-01

    A supramolecular porphyrin nanotube displaying J-aggregation feature was constructed by out-of-plane coordinated bismuth-porphyrin. Significantly, compared to traditional J-aggregated porphyrin suffering from fluorescence and singlet oxygen quenching, the nanotube exhibits excellent bio-imaging ability and enhanced production efficiency of singlet oxygen. The out-of-plane structure of bismuth to porphyrin makes the aggregation an appropriate material for theranostics. Furthermore, it is also a potential radio-therapeutic drug owing to the presence of radio-active bismuth. Thus, the self-assembly of out-of-plane coordinated porphyrin can be a facile approach toward effective therapy of tumors and other diseases.

  7. MC generator TAUOLA: Implementation of resonance chiral theory for two and three meson modes. Comparison with experiment

    SciTech Connect

    Shekhovtsova, O.; Nugent, I. M.; Przedzinski, T.; Roig, P.; Was, Z.

    2012-10-23

    We present a partial upgrade of the Monte Carlo event generator TAUOLA with the two and three hadron decay modes using the theoretical models based on Resonance Chiral Theory. These modes account for 88% of total hadronic width of the tau meson. First results of the model parameters have been obtained using BaBar data for 3{pi} mode.

  8. Tunable noise-like pulse generation in mode-locked Tm fiber laser with a SESAM.

    PubMed

    Mashiko, Yutaka; Fujita, Eisuke; Tokurakawa, Masaki

    2016-11-14

    We report on a tunable noise-like pulse (NLP) generation in a mode-locked Tm fiber laser with a SESAM. A tuning range of 1895-1942 nm, while keeping the spectral bandwidth of 10-19 nm under NLP mode-locked operation, was obtained by a tunable filter based on chromatic dispersion of telescope lenses. At the center wavelength of 1928 nm, the maximum output power of 195 mW with the spectral bandwidth of 18.9 nm was obtained. The repetition rate was 20.5 MHz and the corresponding pulse energy was 9.5 nJ. To our knowledge, this is the first report of a tunable NLP mode-locked laser based on chromatic dispersion of a lens system.

  9. Ultrafast pulse generation in a mode-locked Erbium chip waveguide laser.

    PubMed

    Khurmi, Champak; Hébert, Nicolas Bourbeau; Zhang, Wen Qi; Afshar V, Shahraam; Chen, George; Genest, Jérôme; Monro, Tanya M; Lancaster, David G

    2016-11-28

    We report mode-locked ~1550 nm output of transform-limited ~180 fs pulses from a large mode-area (diameter ~50 μm) guided-wave erbium fluorozirconate glass laser. The passively mode-locked oscillator generates pulses with 25 nm bandwidth at 156 MHz repetition rate and peak-power of 260 W. Scalability to higher repetition rate is demonstrated by transform-limited 410 fs pulse output at 1.3 GHz. To understand the origins of the broad spectral output, the laser cavity is simulated by using a numerical solution to the Ginzburg-Landau equation. This paper reports the widest bandwidth and shortest pulses achieved from an ultra-fast laser inscribed waveguide laser.

  10. Monolithic dual-mode distributed feedback semiconductor laser for tunable continuous-wave terahertz generation.

    PubMed

    Kim, Namje; Shin, Jaeheon; Sim, Eundeok; Lee, Chul Wook; Yee, Dae-Su; Jeon, Min Yong; Jang, Yudong; Park, Kyung Hyun

    2009-08-03

    We report on a monolithic dual-mode semiconductor laser operating in the 1550-nm range as a compact optical beat source for tunable continuous-wave (CW) terahertz (THz) generation. It consists of two distributed feedback (DFB) laser sections and one phase section between them. Each wavelength of the two modes can be independently tuned by adjusting currents in micro-heaters which are fabricated on the top of the each DFB section. The continuous tuning of the CW THz emission from Fe(+)-implanted InGaAs photomixers is successfully demonstrated using our dual-mode laser as the excitation source. The CW THz frequency is continuously tuned from 0.17 to 0.49 THz.

  11. Soliton generation from a fundamentally mode-locked fiber laser with a feed-forward path

    NASA Astrophysics Data System (ADS)

    Wang, Ruixin; Dai, Yitang; Yin, Feifei; Xu, Kun; Li, Jianqiang; Lin, Jintong

    2014-08-01

    We demonstrate for the first time to our knowledge, the soliton generation from a mode-locked erbium-doped fiber laser using a novel saturable absorber (SA), which is realized by combining a dual-drive modulator and an intensity feed-forward path. The laser is fundamentally mode-locked under high-frequency RF signal modulation. Experimentally, the actively mode-locked laser produces a 16.7 MHz repetition rate pulse train with a 1.4 ps pulse width, and the spectrum bandwidth is 2.17 nm. The results demonstrate that the SA supports soliton pulse shaping in the cavity at the fundamental frequency.

  12. Generation of Three Dimensional Body Fitted Coordinates Using Hyperbolic Partial Differential Equations.

    DTIC Science & Technology

    1984-03-01

    Phys., 12, Vol. 2 (1972), 182-195. 3) Thompson , J . F ., F. C. Thames, and C. M. Mastin, Automatic numerical gen- eration of body-fitted curvilinear...coordinate system for field containing any number of arbitrary two-dimensional bodies, 3. Comp. Phys., Vol. 15, (1974), 299-319. 4) Thompson , J . F ., Elliptic

  13. Efficient generation of the cartesian coordinates of truncated icosahedron and related polyhedra.

    PubMed

    Hosoya, H; Maruyama, Y

    2001-01-01

    Efficient algorithms for deriving the analytical expressions of the rectangular coordinates of the vertices of regular polyhedra and truncated icosahedron inscribed in a cube is described and the results are exposed. Various characteristic quantities of the geometrical structure of truncated icosahedron are obtained. Kaleidoscopes for projecting the truncated icosahedron are discussed.

  14. Ultrashort pulse generation by semiconductor mode-locked lasers at 760 nm.

    PubMed

    Wang, Huolei; Kong, Liang; Forrest, Adam; Bajek, David; Haggett, Stephanie E; Wang, Xiaoling; Cui, Bifeng; Pan, Jiaoqing; Ding, Ying; Cataluna, Maria Ana

    2014-10-20

    We demonstrate the first semiconductor mode-locked lasers for ultrashort pulse generation at the 760 nm waveband. Multi-section laser diodes based on an AlGaAs multi-quantum-well structure were passively mode-locked, resulting in the generation of pulses at around 766 nm, with pulse durations down to ~4 ps, at pulse repetition rates of 19.4 GHz or 23.2 GHz (with different laser cavity lengths of 1.8 mm and 1.5 mm, respectively). The influence of the bias conditions on the mode-locking characteristics was investigated for these new lasers, revealing trends which can be ascribed to the interplay of dynamical processes in the saturable absorber and gain sections. It was also found that the front facet reflectivity played a key role in the stability of mode-locking and the occurrence of self-pulsations. These lasers hold significant promise as light sources for multi-photon biomedical imaging, as well as in other applications such as frequency conversion into the ultraviolet and radio-over-fibre communications.

  15. Heterogeneously integrated III-V/silicon dual-mode distributed feedback laser array for terahertz generation.

    PubMed

    Shao, Haifeng; Keyvaninia, Shahram; Vanwolleghem, Mathias; Ducournau, Guillaume; Jiang, Xiaoqing; Morthier, Geert; Lampin, Jean-Francois; Roelkens, Gunther

    2014-11-15

    We demonstrate an integrated distributed feedback (DFB) laser array as a dual-wavelength source for narrowband terahertz (THz) generation. The laser array is composed of four heterogeneously integrated III-V-on-silicon DFB lasers with different lengths enabling dual-mode lasing tolerant to process variations, bias fluctuations, and ambient temperature variations. By optical heterodyning the two modes emitted by the dual-wavelength DFB laser in the laser array using a THz photomixer composed of an uni-traveling carrier photodiode (UTC-PD), a narrow and stable carrier signal with a frequency of 0.357 THz is generated. The central operating frequency and the emitted terahertz wave linewidth are analyzed, along with their dependency on the bias current applied to the laser diode and ambient temperature.

  16. Operation modes of a hydro-generator as a part of the inverter micro hydropower plant

    NASA Astrophysics Data System (ADS)

    Lukutin, B. V.; Shandarova, E. B.; Matukhin, D. L.; Makarova, A. F.; Fuks, I. L.

    2016-04-01

    The paper dwells on the selection problem of power equipment for a stand-alone inverter micro hydropower plant, in particular a hydro-generator, and evaluation of its operation modes. Numerical experiments included the modes calculation of hydroelectric units of the same type with various nominal power, supplied to the consumer according to the unchanged electric load curve. The studies developed requirements for a hydro-turbine and a synchronous generator in terms of a speed range and installed capacity, depending on the load curve. The possibility of using general industrial hydroelectric units with nominal power equal to half-maximum capacity of a typical daily load curve in rural areas was shown.

  17. Acoustic performance of inlet suppressors on an engine generating a single mode

    NASA Technical Reports Server (NTRS)

    Heidelberg, L. J.; Rice, E. J.; Homyak, L.

    1981-01-01

    Three single degree of freedom liners with different open area ratio face sheets were designed for a single spinning mode in order to evaluate an inlet suppressor design method based on mode cutoff ratio. This mode was generated by placing 41 rods in front of the 28 blade fan of a JT15D turbofan engine. At the liner design this near cutoff mode has a theoretical maximum attenuation of nearly 200 dB per L/D. The data show even higher attenuations at the design condition than predicted by the theory for dissipation of a single mode within the liner. This additional attenuation is large for high open area ratios and should be accounted for in the theory. The data show the additional attenuation to be inversely proportional to acoustic resistance. It was thought that the additional attenuation could be caused by reflection and modal scattering at the hard to soft wall interface. A reflection model was developed, and then modified to fit the data. This model was checked against independent (multiple pure tone) data with good agreement.

  18. Passive mode lockers for lasers generating at a wavelength of 1.06 micron

    NASA Astrophysics Data System (ADS)

    Mikhailov, V. P.; Demchuk, M. I.; Lugovskii, A. P.; Sosnovskii, G. M.; Iumashev, K. V.

    1983-04-01

    New polymethine dyes that can be used for the passive mode locking of lasers generating at 1.06 micron are investigated using YAG:Nd as the active element. The effect of introducing various substituents into the heterocyclic nuclei of the end groups of polymethine dyes is discussed. It is shown that substituents generally increase the energy of the ultrashort pulse while also increasing its length.

  19. Fast random number generation with spontaneous emission noise of a single-mode semiconductor laser

    NASA Astrophysics Data System (ADS)

    Zhang, Jianzhong; Zhang, Mingjiang; Liu, Yi; Li, Pu; Yi, Xiaogang; Zhang, Mingtao; Wang, Yuncai

    2016-11-01

    We experimentally demonstrate a 12.5 Gb s-1 random number generator based on measuring the spontaneous emission noise of a single-mode semiconductor laser. The spontaneous emission of light is quantum mechanical in nature and is an inborn physical entropy source of true randomness. By combining a high-speed analog-to-digital converter and off-line processing, random numbers are extracted from the spontaneous emission with the verified randomness. The generator is simple, robust, and with no need of accurately tuning the comparison threshold. The use of semiconductor lasers makes it particularly compatible with the delivery of random numbers in optical networks.

  20. Generation of two-mode bright squeezed light using a noise-suppressed amplified diode laser.

    PubMed

    Zhang, Yun; Hayasaka, Kazuhiro; Kasai, Katsuyuki

    2006-12-25

    We present the generation of nonclassical state using an amplified diode laser as a light source. The intensity noise of an amplified diode laser was significantly suppressed and reached the shot noise limit at 15 MHz using both a filter cavity and resonant optical feedback. Frequency doubling efficiency of 66% and up to 120 mW output power of green has been achieved in cw second-harmonic generation from 1080 nm to 540 nm. Bright two-mode amplitude-squeezed state was generated from a type-II nondegenerate optical parametric amplifier pumped by generated green light. The measured noise reduction is 2.1+/-0.2 dB below the shot-noise level.

  1. Mode 2 Internal Wave Generation and Propagation Near the New Jersey (USA) Shelf Break -Early Fall Season

    DTIC Science & Technology

    2015-03-13

    bathymetry zones on the New Jersey (USA) continental shelf. In the first zone, the upslope propagating mode 2 internal waves were detected in a ~15 km range...distributions, packet evolution and conditions under which mode 2 internal waves are generated on the continental shelf. 13-03-2015 Memorandum Report... Continental shelf Mode 2 internal wave generation and propagation Relation to internal tide October 2011 – September 2013 6534 Naval Research

  2. Experimental Array for Generating Dual Circularly-Polarized Dual-Mode OAM Radio Beams

    PubMed Central

    Bai, Xu-Dong; Liang, Xian-Ling; Sun, Yun-Tao; Hu, Peng-Cheng; Yao, Yu; Wang, Kun; Geng, Jun-Ping; Jin, Rong-Hong

    2017-01-01

    Recently, vortex beam carrying orbital angular momentum (OAM) for radio communications has attracted much attention for its potential of transmitting multiple signals simultaneously at the same frequency, which can be used to increase the channel capacity. However, most of the methods for getting multi-mode OAM radio beams are of complicated structure and very high cost. This paper provides an effective solution of generating dual circularly-polarized (CP) dual-mode OAM beams. The antenna consists of four dual-CP elements which are sequentially rotated 90 degrees in the clockwise direction. Different from all previous published research relating to OAM generation by phased arrays, the four elements are fed with the same phase for both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The dual-mode operation for OAM is achieved through the opposite phase differences generated for LHCP and RHCP, when the dual-CP elements are sequentially rotated in the clockwise direction. The measured results coincide well with the simulated ones, which verified the effectiveness of the proposed design. PMID:28071662

  3. Experimental Array for Generating Dual Circularly-Polarized Dual-Mode OAM Radio Beams

    NASA Astrophysics Data System (ADS)

    Bai, Xu-Dong; Liang, Xian-Ling; Sun, Yun-Tao; Hu, Peng-Cheng; Yao, Yu; Wang, Kun; Geng, Jun-Ping; Jin, Rong-Hong

    2017-01-01

    Recently, vortex beam carrying orbital angular momentum (OAM) for radio communications has attracted much attention for its potential of transmitting multiple signals simultaneously at the same frequency, which can be used to increase the channel capacity. However, most of the methods for getting multi-mode OAM radio beams are of complicated structure and very high cost. This paper provides an effective solution of generating dual circularly-polarized (CP) dual-mode OAM beams. The antenna consists of four dual-CP elements which are sequentially rotated 90 degrees in the clockwise direction. Different from all previous published research relating to OAM generation by phased arrays, the four elements are fed with the same phase for both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The dual-mode operation for OAM is achieved through the opposite phase differences generated for LHCP and RHCP, when the dual-CP elements are sequentially rotated in the clockwise direction. The measured results coincide well with the simulated ones, which verified the effectiveness of the proposed design.

  4. Oblique Bernstein Mode Generation Near the Upper-hybrid Frequency in Solar Pre-flare Plasmas

    NASA Astrophysics Data System (ADS)

    Kryshtal, A.; Fedun, V.; Gerasimenko, S.; Voitsekhovska, A.

    2015-11-01

    We study analytically the generation process of the first harmonics of the pure electron weakly oblique Bernstein modes. This mode can appear as a result of the rise and development of a corresponding instability in a solar active region. We assume that this wave mode is modified by the influence of pair Coulomb collisions and a weak large-scale sub-Dreicer electric field in the pre-flare chromosphere near the footpoints of a flare loop. To describe the pre-flare plasma we used the model of the solar atmosphere developed by Fontenla, Avrett, and Loeser ( Astrophys. J. 406, 319, 1993). We show that the generated first harmonic is close to the upper-hybrid frequency. This generation process begins at the very low threshold values of the sub-Dreicer electric field and well before the beginning of the preheating phase of a flare. We investigate the necessary conditions for the existence of non-damped first harmonics of oblique Bernstein waves with small amplitudes in the flare area.

  5. Novel 3D bismuth-based coordination polymers: Synthesis, structure, and second harmonic generation properties

    SciTech Connect

    Wibowo, Arief C.; Smith, Mark D.; Yeon, Jeongho; Halasyamani, P. Shiv; Loye, Hans-Conrad zur

    2012-11-15

    Two new 3D bismuth containing coordination polymers are reported along with their single crystal structures and SHG properties. Compound 1: Bi{sub 2}O{sub 2}(pydc) (pydc=pyridine-2, 5-dicarboxylate), crystallizes in the monoclinic, polar space group, P2{sub 1} (a=9.6479(9) A, b=4.2349(4) A, c=11.9615(11) A, {beta}=109.587(1) Degree-Sign ), which contains Bi{sub 2}O{sub 2} chains that are connected into a 3D structure via the pydc ligands. Compound 2: Bi{sub 4}Na{sub 4}(1R3S-cam){sub 8}(EtOH){sub 3.1}(H{sub 2}O){sub 3.4} (1R3S cam=1R3S-camphoric acid) crystallizes in the monoclinic, polar space group, P2{sub 1} (a=19.0855(7) A, b=13.7706(5) A, c=19.2429(7) A, {beta}=90.701(1) Degree-Sign ) and is a true 3D coordination polymer. These are two example of SHG compounds prepared using unsymmetric ligands (compound 1) or chiral ligands (compound 2), together with metals that often exhibit stereochemically-active lone pairs, such as Bi{sup 3+}, a synthetic approach that resulted in polar, non-centrosymmetric, 3D metal-organic coordination polymer. - Graphical Abstract: Structures of two new, polar, 3D Bismuth(III)-based coordination polymers: Bi{sub 2}O{sub 2}(pydc) (compound 1), and Bi{sub 4}Na{sub 4}(1R3S-cam){sub 8}(EtOH){sub 3.1}(H{sub 2}O){sub 3.4} (compound 2). Highlights: Black-Right-Pointing-Pointer New, polar, 3D Bismuth(III)-based coordination polymers. Black-Right-Pointing-Pointer First polar bismuth-based coordination polymers synthesized via a 'hybrid' strategy. Black-Right-Pointing-Pointer Combination of stereochemically-active lone pairs and unsymmetrical or chiral ligands. Black-Right-Pointing-Pointer Synthesis of class C-SHG materials based on Kurtz-Perry categories.

  6. Out-of-Plane Coordinated Porphyrin Nanotubes with Enhanced Singlet Oxygen Generation Efficiency

    PubMed Central

    Zhao, Qiang; Wang, Yao; Xu, Yanshuang; Yan, Yun; Huang, Jianbin

    2016-01-01

    A supramolecular porphyrin nanotube displaying J-aggregation feature was constructed by out-of-plane coordinated bismuth-porphyrin. Significantly, compared to traditional J-aggregated porphyrin suffering from fluorescence and singlet oxygen quenching, the nanotube exhibits excellent bio-imaging ability and enhanced production efficiency of singlet oxygen. The out-of-plane structure of bismuth to porphyrin makes the aggregation an appropriate material for theranostics. Furthermore, it is also a potential radio-therapeutic drug owing to the presence of radio-active bismuth. Thus, the self-assembly of out-of-plane coordinated porphyrin can be a facile approach toward effective therapy of tumors and other diseases. PMID:27527403

  7. Gas-generated thermal oxidation of a coordination cluster for an anion-doped mesoporous metal oxide

    PubMed Central

    Hirai, Kenji; Isobe, Shigehito; Sada, Kazuki

    2015-01-01

    Central in material design of metal oxides is the increase of surface area and control of intrinsic electronic and optical properties, because of potential applications for energy storage, photocatalysis and photovoltaics. Here, we disclose a facile method, inspired by geochemical process, which gives rise to mesoporous anion-doped metal oxides. As a model system, we demonstrate that simple calcination of a multinuclear coordination cluster results in synchronic chemical reactions: thermal oxidation of Ti8O10(4-aminobenzoate)12 and generation of gases including amino-group fragments. The gas generation during the thermal oxidation of Ti8O10(4-aminobenzoate)12 creates mesoporosity in TiO2. Concurrently, nitrogen atoms contained in the gases are doped into TiO2, thus leading to the formation of mesoporous N-doped TiO2. The mesoporous N-doped TiO2 can be easily synthesized by calcination of the multinuclear coordination cluster, but shows better photocatalytic activity than the one prepared by a conventional sol-gel method. Owing to an intrinsic designability of coordination compounds, this facile synthetic will be applicable to a wide range of metal oxides and anion dopants. PMID:26681104

  8. Gas-generated thermal oxidation of a coordination cluster for an anion-doped mesoporous metal oxide

    NASA Astrophysics Data System (ADS)

    Hirai, Kenji; Isobe, Shigehito; Sada, Kazuki

    2015-12-01

    Central in material design of metal oxides is the increase of surface area and control of intrinsic electronic and optical properties, because of potential applications for energy storage, photocatalysis and photovoltaics. Here, we disclose a facile method, inspired by geochemical process, which gives rise to mesoporous anion-doped metal oxides. As a model system, we demonstrate that simple calcination of a multinuclear coordination cluster results in synchronic chemical reactions: thermal oxidation of Ti8O10(4-aminobenzoate)12 and generation of gases including amino-group fragments. The gas generation during the thermal oxidation of Ti8O10(4-aminobenzoate)12 creates mesoporosity in TiO2. Concurrently, nitrogen atoms contained in the gases are doped into TiO2, thus leading to the formation of mesoporous N-doped TiO2. The mesoporous N-doped TiO2 can be easily synthesized by calcination of the multinuclear coordination cluster, but shows better photocatalytic activity than the one prepared by a conventional sol-gel method. Owing to an intrinsic designability of coordination compounds, this facile synthetic will be applicable to a wide range of metal oxides and anion dopants.

  9. Novel 3D bismuth-based coordination polymers: Synthesis, structure, and second harmonic generation properties

    NASA Astrophysics Data System (ADS)

    Wibowo, Arief C.; Smith, Mark D.; Yeon, Jeongho; Halasyamani, P. Shiv; zur Loye, Hans-Conrad

    2012-11-01

    Two new 3D bismuth containing coordination polymers are reported along with their single crystal structures and SHG properties. Compound 1: Bi2O2(pydc) (pydc=pyridine-2, 5-dicarboxylate), crystallizes in the monoclinic, polar space group, P21 (a=9.6479(9) Å, b=4.2349(4) Å, c=11.9615(11) Å, β=109.587(1)°), which contains Bi2O2 chains that are connected into a 3D structure via the pydc ligands. Compound 2: Bi4Na4(1R3S-cam)8(EtOH)3.1(H2O)3.4 (1R3S cam=1R3S-camphoric acid) crystallizes in the monoclinic, polar space group, P21 (a=19.0855(7) Å, b=13.7706(5) Å, c=19.2429(7) Å, β=90.701(1)°) and is a true 3D coordination polymer. These are two example of SHG compounds prepared using unsymmetric ligands (compound 1) or chiral ligands (compound 2), together with metals that often exhibit stereochemically-active lone pairs, such as Bi3+, a synthetic approach that resulted in polar, non-centrosymmetric, 3D metal-organic coordination polymer.

  10. Enhanced Catalysis Activity in a Coordinatively Unsaturated Cobalt-MOF Generated via Single-Crystal-to-Single-Crystal Dehydration.

    PubMed

    Ren, Hai-Yun; Yao, Ru-Xin; Zhang, Xian-Ming

    2015-07-06

    Hydrothermal reaction of Co(NO3)2 and terphenyl-3,2",5",3'-tetracarboxyate (H4tpta) generated Co3(OH)2 chains based 3D coordination framework Co3(OH)2(tpta)(H2O)4 (1) that suffered from single-crystal-to-single-crystal dehydration by heating at 160 °C and was transformed into dehydrated Co3(OH)2(tpta) (1a). During the dehydration course, the local coordination environment of part of the Co atoms was transformed from saturated octahedron to coordinatively unsaturated tetrahedron. Heterogenous catalytic experiments on allylic oxidation of cyclohexene show that dehydrated 1a has 6 times enhanced catalytic activity than as-synthesized 1 by using tert-butyl hydroperoxide (t-BuOOH) as oxidant. The activation energy for the oxidation of cylcohexene with 1a catalyst was 67.3 kJ/mol, far below the value with 1 catalysts, which clearly suggested that coordinatively unsaturated Co(II) sites in 1a have played a significant role in decreasing the activation energy. It is interestingly found that heterogeneous catalytic oxidation of cyclohexene in 1a not only gives the higher conversion of 73.6% but also shows very high selectivity toward 2-cyclohexene-1-one (ca. 64.9%), as evidenced in high turnover numbers (ca. 161) based on the open Co(II) sites of 1a catalyst. Further experiments with a radical trap indicate a radical chain mechanism. This work demonstrates that creativity of coordinatively unsaturated metal sites in MOFs could significantly enhance heterogeneous catalytic activity and selectivity.

  11. Anticancer Activity and Modes of Action of (arene) ruthenium(II) Complexes Coordinated to C-, N-, and O-ligands.

    PubMed

    Biersack, Bernhard

    2016-01-01

    An overview of anticancer active (arene)ruthenium(II) complexes coordinated to period 2 element-based ligand systems, i.e., carbon-, nitrogen-, and oxygen-coordinated ligands, is provided in this mini-review. A bridge is forged from the large group of anticancer active ruthenium compounds with monodentate and chelating nitrogen ligands via complexes of O,O-chelating ligands to organometallic ruthenium derivatives coordinated to carbon. (Arene)ruthenium(II) complexes with reduced side-effects and enhanced efficacy against cancer are highlighted. Pertinent literature is covered up to 2014.

  12. The generation of pharyngeal phase of swallow and its coordination with breathing: interaction between the swallow and respiratory central pattern generators.

    PubMed

    Bautista, Tara G; Sun, Qi-Jian; Pilowsky, Paul M

    2014-01-01

    Swallowing and breathing utilize common muscles and an anatomical passage: the pharynx. The risk of aspiration of ingested material is minimized not only by the laryngeal adduction of the vocal folds and laryngeal elevation but also by the precise coordination of swallows with breathing. Namely, swallows: (1) are preferentially initiated in the postinspiratory/expiratory phase, (2) are accompanied by a brief apnea, and (3) are often followed by an expiration and delay of the next breath. This review summarizes the expiratory evidence on the brainstem regions comprising the central pattern generator (CPG) that produces the pharyngeal stage of swallow, how the motor acts of swallowing and breathing are coordinated, and lastly, brainstem regions where the swallowing and respiratory CPGs may interact in order to ensure "safe" swallows.

  13. Design and optimization of a multi-element piezoelectric transducer for mode-selective generation of guided waves

    NASA Astrophysics Data System (ADS)

    Yazdanpanah Moghadam, Peyman; Quaegebeur, Nicolas; Masson, Patrice

    2016-07-01

    A novel multi-element piezoelectric transducers (MEPT) is designed, optimized, machined and experimentally tested to improve structural health monitoring systems for mode-selective generation of guided waves (GW) in an isotropic structure. GW generation using typical piezoceramics makes the signal processing and consequently damage detection very complicated because at any driving frequency at least two fundamental symmetric (S 0) and antisymmetric (A 0) modes are generated. To prevent this, mode selective transducer design is proposed based on MEPT. A numerical method is first developed to extract the interfacial stress between a single piezoceramic element and a host structure and then used as the input of an analytical model to predict the GW propagation through the thickness of an isotropic plate. Two novel objective functions are proposed to optimize the interfacial shear stress for both suppressing unwanted mode(s) and maximizing the desired mode. Simplicity and low manufacturing cost are two main targets driving the design of the MEPT. A prototype MEPT is then manufactured using laser micro-machining. An experimental procedure is presented to validate the performances of the MEPT as a new solution for mode-selective GW generation. Experimental tests illustrate the high capability of the MEPT for mode-selective GW generation, as unwanted mode is suppressed by a factor up to 170 times compared with the results obtained with a single piezoceramic.

  14. Selective coherent phonon-mode generation in single-wall carbon nanotubes.

    PubMed

    Nugraha, Ahmad R T; Hasdeo, Eddwi H; Saito, Riichiro

    2017-02-08

    The pulse-train technique within ultrafast pump-probe spectroscopy is theoretically investigated to excite a specific coherent phonon mode while suppressing the other phonon modes generated in single-wall carbon nanotubes (SWNTs). In particular, we focus on the selectivity of the radial breathing mode (RBM) and the G-band for a given SWNT. We find that if the repetition period of the pulse train matches with the integer multiple of the RBM phonon period, the RBM amplitude can be maintained while the amplitudes of the other modes are suppressed. As for the G-band, when we apply a repetition period of a half-integer multiple of the RBM period, the RBM can be suppressed because of destructive interference, while the G-band still survives. It is also possible to keep the G-band and suppress the RBM by applying a repetition period that matches with the integer multiple of the G-band phonon period. However, in this case we have to use a large number of laser pulses having a property of "magic ratio" of the G-band and RBM periods.

  15. Selective coherent phonon-mode generation in single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Nugraha, Ahmad R. T.; Hasdeo, Eddwi H.; Saito, Riichiro

    2017-02-01

    The pulse-train technique within ultrafast pump-probe spectroscopy is theoretically investigated to excite a specific coherent phonon mode while suppressing the other phonon modes generated in single-wall carbon nanotubes (SWNTs). In particular, we focus on the selectivity of the radial breathing mode (RBM) and the G-band for a given SWNT. We find that if the repetition period of the pulse train matches with the integer multiple of the RBM phonon period, the RBM amplitude can be maintained while the amplitudes of the other modes are suppressed. As for the G-band, when we apply a repetition period of a half-integer multiple of the RBM period, the RBM can be suppressed because of destructive interference, while the G-band still survives. It is also possible to keep the G-band and suppress the RBM by applying a repetition period that matches with the integer multiple of the G-band phonon period. However, in this case we have to use a large number of laser pulses having a property of “magic ratio” of the G-band and RBM periods.

  16. Enhanced Third Harmonic Generation in Single Germanium Nanodisks Excited at the Anapole Mode.

    PubMed

    Grinblat, Gustavo; Li, Yi; Nielsen, Michael P; Oulton, Rupert F; Maier, Stefan A

    2016-07-13

    We present an all-dielectric germanium nanosystem exhibiting a strong third order nonlinear response and efficient third harmonic generation in the optical regime. A thin germanium nanodisk shows a pronounced valley in its scattering cross section at the dark anapole mode, while the electric field energy inside the disk is maximized due to high confinement within the dielectric. We investigate the dependence of the third harmonic signal on disk size and pump wavelength to reveal the nature of the anapole mode. Each germanium nanodisk generates a high effective third order susceptibility of χ((3)) = 4.3 × 10(-9) esu, corresponding to an associated third harmonic conversion efficiency of 0.0001% at an excitation wavelength of 1650 nm, which is 4 orders of magnitude greater than the case of an unstructured germanium reference film. Furthermore, the nonlinear conversion via the anapole mode outperforms that via the radiative dipolar resonances by about 1 order of magnitude, which is consistent with our numerical simulations. These findings open new possibilities for the optimization of upconversion processes on the nanoscale through the appropriate engineering of suitable dielectric materials.

  17. Continuous Variable Cluster State Generation over the Optical Spatial Mode Comb

    DOE PAGES

    Pooser, Raphael C.; Jing, Jietai

    2014-10-20

    One way quantum computing uses single qubit projective measurements performed on a cluster state (a highly entangled state of multiple qubits) in order to enact quantum gates. The model is promising due to its potential scalability; the cluster state may be produced at the beginning of the computation and operated on over time. Continuous variables (CV) offer another potential benefit in the form of deterministic entanglement generation. This determinism can lead to robust cluster states and scalable quantum computation. Recent demonstrations of CV cluster states have made great strides on the path to scalability utilizing either time or frequency multiplexingmore » in optical parametric oscillators (OPO) both above and below threshold. The techniques relied on a combination of entangling operators and beam splitter transformations. Here we show that an analogous transformation exists for amplifiers with Gaussian inputs states operating on multiple spatial modes. By judicious selection of local oscillators (LOs), the spatial mode distribution is analogous to the optical frequency comb consisting of axial modes in an OPO cavity. We outline an experimental system that generates cluster states across the spatial frequency comb which can also scale the amount of quantum noise reduction to potentially larger than in other systems.« less

  18. Rotman Lens-Based Circular Array for Generating Five-mode OAM Radio Beams

    PubMed Central

    Bai, Xu-Dong; Liang, Xian-Ling; Li, Jian-Ping; Wang, Kun; Geng, Jun-Ping; Jin, Rong-Hong

    2016-01-01

    Recently, vortex beam carrying orbital angular momentum (OAM) for radio communications has attracted much attention for its potential of transmitting multiple signals simultaneously at the same frequency, which can be used to increase the channel capacity. However, most of the methods for getting multi-mode OAM radio beams remain up to now mainly at simulation level, since their implementations are of complicated structure and very high cost. This paper provides an effective design of generating five-mode OAM radio beams by using the Rotman lens-fed antenna array. The Rotman lens is a viable beamforming approach instead of electronically scanned arrays for its low cost and the ease of implementation. The lens-fed array employs a two-layer structure for size reduction, and the lens body and the antenna array are segregated by a common ground plane to eliminate spurious radiation and thus improve the performance of the OAM beams. The measured results coincide with the simulated ones, which verified the effectiveness of the proposed design for generating multi-mode OAM beams. PMID:27283738

  19. Energy-Efficient Next-Generation Passive Optical Networks Based on Sleep Mode and Heuristic Optimization

    NASA Astrophysics Data System (ADS)

    Zulai, Luis G. T.; Durand, Fábio R.; Abrão, Taufik

    2015-05-01

    In this article, an energy-efficiency mechanism for next-generation passive optical networks is investigated through heuristic particle swarm optimization. Ten-gigabit Ethernet-wavelength division multiplexing optical code division multiplexing-passive optical network next-generation passive optical networks are based on the use of a legacy 10-gigabit Ethernet-passive optical network with the advantage of using only an en/decoder pair of optical code division multiplexing technology, thus eliminating the en/decoder at each optical network unit. The proposed joint mechanism is based on the sleep-mode power-saving scheme for a 10-gigabit Ethernet-passive optical network, combined with a power control procedure aiming to adjust the transmitted power of the active optical network units while maximizing the overall energy-efficiency network. The particle swarm optimization based power control algorithm establishes the optimal transmitted power in each optical network unit according to the network pre-defined quality of service requirements. The objective is controlling the power consumption of the optical network unit according to the traffic demand by adjusting its transmitter power in an attempt to maximize the number of transmitted bits with minimum energy consumption, achieving maximal system energy efficiency. Numerical results have revealed that it is possible to save 75% of energy consumption with the proposed particle swarm optimization based sleep-mode energy-efficiency mechanism compared to 55% energy savings when just a sleeping-mode-based mechanism is deployed.

  20. Rotating rake design for unique measurement of fan-generated spinning acoustic modes

    NASA Technical Reports Server (NTRS)

    Konno, Kevin E.; Hausmann, Clifford R.

    1993-01-01

    In light of the current emphasis on noise reduction in subsonic aircraft design, NASA has been actively studying the source of and propagation of noise generated by subsonic fan engines. NASA/LeRC has developed and tested a unique method of accurately measuring these spinning acoustic modes generated by an experimental fan. This mode measuring method is based on the use of a rotating microphone rake. Testing was conducted in the 9 x 15 Low-speed Wind Tunnel. The rotating rake was tested with the Advanced Ducted Propeller (ADP) model. This memorandum discusses the design and performance of the motor/drive system for the fan-synchronized rotating acoustic rake. This novel motor/drive design approach is now being adapted for additional acoustic mode studies in new test rigs as baseline data for the future design of active noise control for subsonic fan engines. Included in this memorandum are the research requirements, motor/drive specifications, test performance results, and a description of the controls and software involved.

  1. Continuous Variable Cluster State Generation over the Optical Spatial Mode Comb

    SciTech Connect

    Pooser, Raphael C.; Jing, Jietai

    2014-10-20

    One way quantum computing uses single qubit projective measurements performed on a cluster state (a highly entangled state of multiple qubits) in order to enact quantum gates. The model is promising due to its potential scalability; the cluster state may be produced at the beginning of the computation and operated on over time. Continuous variables (CV) offer another potential benefit in the form of deterministic entanglement generation. This determinism can lead to robust cluster states and scalable quantum computation. Recent demonstrations of CV cluster states have made great strides on the path to scalability utilizing either time or frequency multiplexing in optical parametric oscillators (OPO) both above and below threshold. The techniques relied on a combination of entangling operators and beam splitter transformations. Here we show that an analogous transformation exists for amplifiers with Gaussian inputs states operating on multiple spatial modes. By judicious selection of local oscillators (LOs), the spatial mode distribution is analogous to the optical frequency comb consisting of axial modes in an OPO cavity. We outline an experimental system that generates cluster states across the spatial frequency comb which can also scale the amount of quantum noise reduction to potentially larger than in other systems.

  2. Terahertz generation in GaN diodes in the limited space-charge accumulation mode

    NASA Astrophysics Data System (ADS)

    Barry, E. A.; Sokolov, V. N.; Kim, K. W.; Trew, R. J.

    2008-06-01

    The conditions for terahertz power generation are investigated theoretically in a nanoscale GaN-based diode coupled to an external resonant circuit for operation in the limited space-charge accumulation (LSA) mode under the high-field transport regime. The generation criteria are revisited in terms of a phase plane analysis of the diode high-field transport and circuit equations. Based on a Fourier series analysis, the waveforms of the diode voltage and current are examined and the generated power and conversion efficiencies are estimated at the fundamental and lowest harmonic frequencies. The advantages of group-III nitride LSA diodes are elucidated including their ability to simultaneously achieve large output powers (>10 mW) and high dc-to-rf conversion efficiencies (>1%) over a wide range of frequencies near 1 THz.

  3. SU-F-BRB-16: A Spreadsheet Based Automatic Trajectory GEnerator (SAGE): An Open Source Tool for Automatic Creation of TrueBeam Developer Mode Robotic Trajectories

    SciTech Connect

    Etmektzoglou, A; Mishra, P; Svatos, M

    2015-06-15

    Purpose: To automate creation and delivery of robotic linac trajectories with TrueBeam Developer Mode, an open source spreadsheet-based trajectory generation tool has been developed, tested and made freely available. The computing power inherent in a spreadsheet environment plus additional functions programmed into the tool insulate users from the underlying schema tedium and allow easy calculation, parameterization, graphical visualization, validation and finally automatic generation of Developer Mode XML scripts which are directly loadable on a TrueBeam linac. Methods: The robotic control system platform that allows total coordination of potentially all linac moving axes with beam (continuous, step-and-shoot, or combination thereof) becomes available in TrueBeam Developer Mode. Many complex trajectories are either geometric or can be described in analytical form, making the computational power, graphing and programmability available in a spreadsheet environment an easy and ideal vehicle for automatic trajectory generation. The spreadsheet environment allows also for parameterization of trajectories thus enabling the creation of entire families of trajectories using only a few variables. Standard spreadsheet functionality has been extended for powerful movie-like dynamic graphic visualization of the gantry, table, MLC, room, lasers, 3D observer placement and beam centerline all as a function of MU or time, for analysis of the motions before requiring actual linac time. Results: We used the tool to generate and deliver extended SAD “virtual isocenter” trajectories of various shapes such as parameterized circles and ellipses. We also demonstrated use of the tool in generating linac couch motions that simulate respiratory motion using analytical parameterized functions. Conclusion: The SAGE tool is a valuable resource to experiment with families of complex geometric trajectories for a TrueBeam Linac. It makes Developer Mode more accessible as a vehicle to quickly

  4. Re-inscribing Gender in New Modes of Medical Expertise: The Investigator–Coordinator Relationship in the Clinical Trials Industry

    PubMed Central

    Fisher, Jill A.

    2011-01-01

    This article analyses the ways in which research coordinators forge professional identities in the highly gendered organizational context of the clinic. Drawing upon qualitative research on the organization of the clinical trials industry (that is, the private sector, for profit auxiliary companies that support pharmaceutical drug studies), this article explores the relationships between predominantly male physician-investigators and female research coordinators and the constitution of medical expertise in pharmaceutical drug development. One finding is that coordinators actively seek to establish relationships with investigators that mirror traditional doctor–nurse relationships, in which the feminized role is subordinated and devalued. Another finding is that the coordinators do, in fact, have profound research expertise that is frequently greater than that of the investigators. The coordinators develop expertise on pharmaceutical products and diseases through their observations of the patterns that occur in patient–participants’ responses to investigational drugs. The article argues, however, that the nature of the relationships between coordinators and investigators renders invisible the coordinators’ expertise. In this context, gender acts as a persistent social structure shaping both coordinators’ and investigators’ perceptions of who can be recognized as having authority and power in the workplace. PMID:21394219

  5. Generation of three-dimensional body-fitted coordinates using hyperbolic partial differential equations

    NASA Technical Reports Server (NTRS)

    Steger, J. L.; Rizk, Y. M.

    1985-01-01

    An efficient numerical mesh generation scheme capable of creating orthogonal or nearly orthogonal grids about moderately complex three dimensional configurations is described. The mesh is obtained by marching outward from a user specified grid on the body surface. Using spherical grid topology, grids have been generated about full span rectangular wings and a simplified space shuttle orbiter.

  6. A mode converter to generate a Gaussian-like mode for injection into the VENUS electron cyclotron resonance ion source

    SciTech Connect

    Lyneis, C. Benitez, J.; Hodgkinson, A.; Strohmeier, M.; Todd, D.; Plaum, B.; Thuillier, T.

    2014-02-15

    A number of superconducting electron cyclotron resonance (ECR) ion sources use gyrotrons at either 24 or 28 GHz for ECR heating. In these systems, the microwave power is launched into the plasma using the TE{sub 01} circular waveguide mode. This is fundamentally different and may be less efficient than the typical rectangular, linearly polarized TE{sub 10} mode used for launching waves at lower frequencies. To improve the 28 GHz microwave coupling in VENUS, a TE{sub 01}-HE{sub 11} mode conversion system has been built to test launching HE{sub 11} microwave power into the plasma chamber. The HE{sub 11} mode is a quasi-Gaussian, linearly polarized mode, which should couple strongly to the plasma electrons. The mode conversion is done in two steps. First, a 0.66 m long “snake” converts the TE{sub 01} mode to the TE{sub 11} mode. Second, a corrugated circular waveguide excites the HE{sub 11} mode, which is launched directly into the plasma chamber. The design concept draws on the development of similar devices used in tokamaks and stellerators. The first tests of the new coupling system are described below.

  7. Low-Power Polling Mode of the Next-Generation IMES2 Implantable Wireless EMG Sensor

    PubMed Central

    DeMichele, Glenn A.; Hu, Zhe; Troyk, Philip R.; Chen, Hongnan; Weir, Richard F. ff.

    2015-01-01

    The IMES1 Implantable MyoElectric Sensor device is currently in human clinical trials led by the Alfred Mann Foundation. The IMES is implanted in a residual limb and is powered wirelessly using a magnetic field. EMG signals resulting from the amputee’s voluntary movement are amplified and transmitted wirelessly by the IMES to an external controller which controls movement of an external motorized prosthesis. Development of the IMES technology is on-going, producing the next-generation IMES2. Among various improvements, a new feature of the IMES2 is a lowpower polling mode. In this low-power mode, the IMES2 power consumption can be dramatically reduced when the limb is inactive through the use of a polled sampling. With the onset of EMG activity, the IMES2 system can switch to the normal higher sample rate to allow the acquisition of high-fidelity EMG data for prosthesis control. PMID:25570642

  8. Generation of super-Gaussian modes in Nd:YAG lasers with graded-phase mirrors

    NASA Astrophysics Data System (ADS)

    Gerber, Michael; Graf, Thomas

    2003-11-01

    To change the intensity distribution of the fundamental mode in a Nd:YAG laser resonator to a top-hat profile we developed and used a dielectric graded-phase mirror. A super-Gaussian mode of the sixth order was generated by means of a graded-phase mirror with a simple ring-shaped phase step on a spherical reflector. The depth of the ring was 90 nm. The graded-phase mirror was manufactured with an ordinary vapor deposition technique. An annular mask with a thickness of 10 μm was used to avoid the deposition of the LaF3 vapor at the position of the ring. Laser experiments with continuous-wave and repetitively pulsed dioed-laser pumping were performed and compared. The results are in excellent agreement with the theory.

  9. Higher and sub-harmonic Lamb wave mode generation due to debond-induced contact nonlinearity

    NASA Astrophysics Data System (ADS)

    Guha, Anurup; Bijudas, C. R.

    2016-04-01

    Non-cumulative higher and sub-harmonic Lamb wave mode generation as a result of partial-debond of piezoelectric wafer transducers (PWT) bonded onto an Aluminium plate, is numerically investigated and experimentally validated. The influence of excitation frequency on the extent of nonlinearity due to clapping mechanism of the partially-debonded PWTs is discussed. A set of specific frequency range is arrived at based on the Eigen-value and Harmonic analyses of PWTs used in the model. It is found that, at these frequencies, which are integral multiple of the first width-direction mode of a PWT, significantly higher amplitudes of higher-harmonics are observed. It is also seen that at specific debond-positions and lengths, sharp sub-harmonics in addition to higher-harmonics are present. Signal processing is carried out using Fast Fourier transform, which is normalized for comparisons.

  10. Model OA Wind Turbine Generator FEMA (Failure Modes and Effects Analysis)

    SciTech Connect

    Klein, W.E. . Plum Brook Station); Lalli, V.R. . Lewis Research Center)

    1989-10-01

    This report presents the results of Failure Modes and Effects Analysis (FMEA) conducted for the Wind Turbine Generators. The FMEA was performed for the functional modes of each system, subsystem, or component. The single-point failures were eliminated for most of the systems. The blade system was the only exception. The qualitative probability of a blade separating was estimated at Level D-remote. Many changes were made to the hardware as a result of this analysis. The most significant change was the addition of the safety system. Operational experience and need to improve machine availability have resulted in subsequent changes to the various systems which are also reflected in this FMEA. 2 refs., 3 figs.

  11. Low-power polling mode of the next-generation IMES2 implantable wireless EMG sensor.

    PubMed

    DeMichele, Glenn A; Hu, Zhe; Troyk, Philip R; Chen, Hongnan; Weir, Richard F ff

    2014-01-01

    The IMES1 Implantable MyoElectric Sensor device is currently in human clinical trials led by the Alfred Mann Foundation. The IMES is implanted in a residual limb and is powered wirelessly using a magnetic field. EMG signals resulting from the amputee's voluntary movement are amplified and transmitted wirelessly by the IMES to an external controller which controls movement of an external motorized prosthesis. Development of the IMES technology is on-going, producing the next-generation IMES2. Among various improvements, a new feature of the IMES2 is a low-power polling mode. In this low-power mode, the IMES2 power consumption can be dramatically reduced when the limb is inactive through the use of a polled sampling. With the onset of EMG activity, the IMES2 system can switch to the normal higher sample rate to allow the acquisition of high-fidelity EMG data for prosthesis control.

  12. Pilot/Controller Coordinated Decision Making in the Next Generation Air Transportation System

    NASA Technical Reports Server (NTRS)

    Bearman, Chris; Miller, Ronald c.; Orasanu, Judith M.

    2011-01-01

    Introduction: NextGen technologies promise to provide considerable benefits in terms of enhancing operations and improving safety. However, there needs to be a thorough human factors evaluation of the way these systems will change the way in which pilot and controllers share information. The likely impact of these new technologies on pilot/controller coordinated decision making is considered in this paper using the "operational, informational and evaluative disconnect" framework. Method: Five participant focus groups were held. Participants were four experts in human factors, between x and x research students and a technical expert. The participant focus group evaluated five key NextGen technologies to identify issues that made different disconnects more or less likely. Results: Issues that were identified were: Decision Making will not necessarily improve because pilots and controllers possess the same information; Having a common information source does not mean pilots and controllers are looking at the same information; High levels of automation may lead to disconnects between the technology and pilots/controllers; Common information sources may become the definitive source for information; Overconfidence in the automation may lead to situations where appropriate breakdowns are not initiated. Discussion: The issues that were identified lead to recommendations that need to be considered in the development of NextGen technologies. The current state of development of these technologies provides a good opportunity to utilize recommendations at an early stage so that NextGen technologies do not lead to difficulties in resolving breakdowns in coordinated decision making.

  13. FELIX-1.0: A finite element solver for the time dependent generator coordinate method with the Gaussian overlap approximation

    SciTech Connect

    Regnier, D.; Verriere, M.; Dubray, N.; Schunck, N.

    2015-11-30

    In this study, we describe the software package FELIX that solves the equations of the time-dependent generator coordinate method (TDGCM) in NN-dimensions (N ≥ 1) under the Gaussian overlap approximation. The numerical resolution is based on the Galerkin finite element discretization of the collective space and the Crank–Nicolson scheme for time integration. The TDGCM solver is implemented entirely in C++. Several additional tools written in C++, Python or bash scripting language are also included for convenience. In this paper, the solver is tested with a series of benchmarks calculations. We also demonstrate the ability of our code to handle a realistic calculation of fission dynamics.

  14. Fast Generation of Ensembles of Cosmological N-Body Simulations via Mode-Resampling

    SciTech Connect

    Schneider, M D; Cole, S; Frenk, C S; Szapudi, I

    2011-02-14

    We present an algorithm for quickly generating multiple realizations of N-body simulations to be used, for example, for cosmological parameter estimation from surveys of large-scale structure. Our algorithm uses a new method to resample the large-scale (Gaussian-distributed) Fourier modes in a periodic N-body simulation box in a manner that properly accounts for the nonlinear mode-coupling between large and small scales. We find that our method for adding new large-scale mode realizations recovers the nonlinear power spectrum to sub-percent accuracy on scales larger than about half the Nyquist frequency of the simulation box. Using 20 N-body simulations, we obtain a power spectrum covariance matrix estimate that matches the estimator from Takahashi et al. (from 5000 simulations) with < 20% errors in all matrix elements. Comparing the rates of convergence, we determine that our algorithm requires {approx}8 times fewer simulations to achieve a given error tolerance in estimates of the power spectrum covariance matrix. The degree of success of our algorithm indicates that we understand the main physical processes that give rise to the correlations in the matter power spectrum. Namely, the large-scale Fourier modes modulate both the degree of structure growth through the variation in the effective local matter density and also the spatial frequency of small-scale perturbations through large-scale displacements. We expect our algorithm to be useful for noise modeling when constraining cosmological parameters from weak lensing (cosmic shear) and galaxy surveys, rescaling summary statistics of N-body simulations for new cosmological parameter values, and any applications where the influence of Fourier modes larger than the simulation size must be accounted for.

  15. A precise length etalon generator controlled by femtosecond mode-locked laser

    NASA Astrophysics Data System (ADS)

    Šmid, Radek; Čip, Ondřej; Lazar, Josef

    2007-09-01

    The progress in the field of optical frequency standards is oriented to femtosecond mode-locked lasers stabilized by technique of the optical frequency synthesis. Such a laser produces a supercontinuum light, which is composed of a cluster of coherent frequency components in certain interval of wavelengths. A value of the repetition rate of femtosecond pulses determines (in the frequency domain) spacing of these coherent components. If we control the mode-locked laser by means of i.e. atomic clocks we ensure frequency of these components very stable. With respect to definition of SI unit "one meter" on basis of speed of light the stabilized mode-locked laser can be used for implementation of this definition by non-traditional way. In the work we present our proposal of a system, which converts excellent frequency stability of components generated by the mode-locked laser to a net of discrete absolute lengths represented by a distance of two mirrors of an optical resonator. On basis of theory, the optical resonator with a cavity length has a periodic frequency spectrum Similarly the frequency of i-th comb component could be written as: f i = f ceo + i f rep, where f ceo is the comb offset frequency and f rep is the repetition rate. For the simplicity we presume the offset frequency f ceo equals to zero. If the supercontinuum beam of the mode-locked laser illuminates the resonator and at the same time the cavity length L is adjusted to length L p = c / (2 p f rep ) then both spectra fit. The symbol 'p' is an integer value. It produces intensity maximum in the output of the cavity, which is detected by a photodetector and locked in the servo-loop. For absolute discrete values of cavity lengths L p that well satisfy the condition above we obtain precise etalons of length.

  16. Enhanced second harmonic generation in coupled semiconductor whispering gallery mode microresonators

    NASA Astrophysics Data System (ADS)

    Dumeige, Yannick

    2009-02-01

    It has been shown that doubly resonant microcavities can be used to obtain miniaturized parametric devices leading for example to efficient second-harmonic generation (SHG). First we will briefly recall the basic properties of SHG in III-V semiconductor whispering gallery mode microdisks or microrings. Then we will show theoretically that by coupling such microresonators and by using the artificial dispersion of a side-coupled integrated spaced sequence of resonators (SCISSOR) it is possible to adapt the Fresnel phase-matching technique to the case of highly confining waveguides or to enhance the second order nonlinear properties of a semiconductor waveguide by slowing fundamental and second-harmonic waves.

  17. The organic fraction of bubble-generated, accumulation mode Sea Spray Aerosol (SSA)

    NASA Astrophysics Data System (ADS)

    Modini, R. L.; Harris, B.; Ristovski, Z. D.

    2010-03-01

    Recent studies have detected a dominant accumulation mode (~100 nm) in the Sea Spray Aerosol (SSA) number distribution. There is evidence to suggest that particles in this mode are composed primarily of organics. To investigate this hypothesis we conducted experiments on NaCl, artificial SSA and natural SSA particles with a Volatility-Hygroscopicity-Tandem-Differential-Mobility-Analyser (VH-TDMA). NaCl particles were atomiser generated and a bubble generator was constructed to produce artificial and natural SSA particles. Natural seawater samples for use in the bubble generator were collected from biologically active, terrestrially-affected coastal water in Moreton Bay, Australia. Differences in the VH-TDMA-measured volatility curves of artificial and natural SSA particles were used to investigate and quantify the organic fraction of natural SSA particles. Hygroscopic Growth Factor (HGF) data, also obtained by the VH-TDMA, were used to confirm the conclusions drawn from the volatility data. Both datasets indicated that the organic fraction of our natural SSA particles evaporated in the VH-TDMA over the temperature range 170-200 °C. The organic volume fraction for 71-77 nm natural SSA particles was 8±6%. Organic volume fraction did not vary significantly with varying water residence time (40 s to 24 h) in the bubble generator or SSA particle diameter in the range 38-173 nm. At room temperature we measured shape- and Kelvin-corrected HGF at 90% RH of 2.46±0.02 for NaCl, 2.35±0.02 for artifical SSA and 2.26±0.02 for natural SSA particles. Overall, these results suggest that the natural accumulation mode SSA particles produced in these experiments contained only a minor organic fraction, which had little effect on hygroscopic growth. Our measurement of 8±6% is an order of magnitude below two previous measurements of the organic fraction in SSA particles of comparable sizes. We stress that our results were obtained using coastal seawater and they can't necessarily

  18. The organic fraction of bubble-generated, accumulation mode Sea Spray Aerosol (SSA)

    NASA Astrophysics Data System (ADS)

    Modini, R. L.; Harris, B.; Ristovski, Z. D.

    2009-10-01

    Recent studies have detected a dominant accumulation mode (~100 nm) in the Sea Spray Aerosol (SSA) number distribution. There is evidence to suggest that particles in this mode are composed primarily of organics. To investigate this hypothesis we conducted experiments on NaCl, artificial SSA and natural SSA particles with a Volatility-Hygroscopicity-Tandem-Differential-Mobility-Analyser (VH-TDMA). NaCl particles were atomiser generated and a bubble generator was constructed to produce artificial and natural SSA particles. Natural seawater samples for use in the bubble generator were collected from biologically active, terrestrially-affected coastal water in Moreton Bay, Australia. Differences in the VH-TDMA-measured volatility curves of artificial and natural SSA particles were used to investigate and quantify the organic fraction of natural SSA particles. Hygroscopic Growth Factor (HGF) data, also obtained by the VH-TDMA, were used to confirm the conclusions drawn from the volatility data. Both datasets indicated that the organic fraction of our natural SSA particles evaporated in the VH-TDMA over the temperature range 170-200°C. The organic volume fraction for 71-77 nm natural SSA particles was 8±6%. Organic volume fraction did not vary significantly with varying water residence time (40 s0 to 24 h) in the bubble generator or SSA particle diameter in the range 38-173 nm. At room temperature we measured shape- and Kelvin-corrected HGF at 90% RH of 2.46±0.02 for NaCl, 2.35±0.02 for artifical SSA and 2.26±0.02 for natural SSA particles. Overall, these results suggest that the natural accumulation mode SSA particles produced in these experiments contained only a minor organic fraction, which had little effect on hygroscopic growth. Our measurement of 8±6% is an order of magnitude below two previous measurements of the organic fraction in SSA particles of comparable sizes. Further studies with a variety of different seawaters are required to better quantify how

  19. The Effects of Forcing Modes on the Simulations of Tidally Generated Internal Bores and Solitons

    NASA Astrophysics Data System (ADS)

    Piacsek, S.; Warn-Varnas, A.; Smolarkiewicz, P.; Martin, P.

    2008-12-01

    Numerical experiments were performed on the generation of internal waves by barotropic tidal currents flowing over strongly varying topography, such as sills in straits. The studies concentrated on two aspects of the simulations: (a) the amplitude of the generated waves as functions of tidal velocities, and (b) amplitudes obtained with different modes of forcing prescriptions, such as boundary vs. volume forcing, or analytic vs. model-generated currents. The tidal velocities were obtained from three tidal components, the M2, K1 and O1 tides, and the model currents were computed with a hydrostatic model. In the boundary-forcing approach, the current variations are prescribed as normal inflow at the respective boundaries. In the volume-forcing approach, the currents are prescribed at all interior points, with the model currents already adapted to the interior topography, but the analytic sinusoidal currents had to undergo a flux-conservation modification. Simulations over both idealized topographies, and the sills of the Luzon Strait and South China Sea were carried out. Propagation comparisons were also made with those of the "shape-preserving", analytically constructed type solitons (solutions of the KDV equation).. For tidal currents in the 10-30 cm/sec range, the generated perturbation densities typically ranged peak-to-peak from 1.6 to 3.5 kg/m3, and the vertical velocities from 25 to 70 cm/sec. The analytic solitons maintained their amplitudes during propagation better than the tidally-generated signals.

  20. Temperature effect on the performance of a dissipative dielectric elastomer generator with failure modes

    NASA Astrophysics Data System (ADS)

    Chen, S. E.; Deng, L.; He, Z. C.; Li, Eric; Li, G. Y.

    2016-05-01

    Research on dielectric elastomer generators (DEGs) which can be utilized to convert mechanical energy to electrical energy has gained wide attention lately. However, very few works account for the operating temperature, viscoelasticity and current leakage in the analysis of DEGs simultaneously. In this study, under several compound four-stroke conversion cycles, the electromechanical performance and energy conversion of a dissipative DEG made of a very-high-bond (VHB) elastomer are investigated at different operating temperatures. The performance parameters such as energy density and conversion efficiency are calculated under different temperatures. Moreover, the common failure modes of the generator are considered: material rupture, loss of tension, electrical breakdown and electromechanical instability. The numerical results have distinctly shown that the operating temperature plays an important role in the performance of DEGs, which could possibly make a larger conversion efficiency for the DEG.

  1. Femtosecond pulse generation from a topological insulator mode-locked fiber laser.

    PubMed

    Liu, Hao; Zheng, Xu-Wu; Liu, Meng; Zhao, Nian; Luo, Ai-Ping; Luo, Zhi-Chao; Xu, Wen-Cheng; Zhang, Han; Zhao, Chu-Jun; Wen, Shuang-Chun

    2014-03-24

    We reported on the generation of femtosecond pulse in a fiber ring laser by using a polyvinyl alcohol (PVA)-based topological insulator (TI), Bi2Se3 saturable absorber (SA). The PVA-TI composite has a low saturable optical intensity of 12 MW/cm2 and a modulation depth of ~3.9%. By incorporating the fabricated PVA-TISA into a fiber laser, mode-locking operation could be achieved at a low pump threshold of 25 mW. After an optimization of the cavity parameters, optical pulse with ~660 fs centered at 1557.5 nm wavelength had been generated. The experimental results demonstrate that the PVA could be an excellent host material for fabricating high-performance TISA, and also indicate that the filmy PVA-TISA is indeed a good candidate for ultrafast saturable absorption device.

  2. Generation of watt-level single-longitudinal-mode output from cladding-pumped short fiber lasers.

    PubMed

    Qiu, T; Suzuki, S; Schülzgen, A; Li, L; Polynkin, A; Temyanko, V; Moloney, J V; Peyghambarian, N

    2005-10-15

    We generate as much as 1.6 W of continuous-wave 1550 nm single-longitudinal-mode output from a cladding pumped Er-Yb codoped phosphate fiber laser. This power is to our knowledge among the highest in single-longitudinal-mode fiber lasers. The narrowband fiber Bragg grating output coupler is demonstrated to be an effective element for providing the single-longitudinal-mode selection.

  3. Accurate Gaussian basis sets for atomic and molecular calculations obtained from the generator coordinate method with polynomial discretization.

    PubMed

    Celeste, Ricardo; Maringolo, Milena P; Comar, Moacyr; Viana, Rommel B; Guimarães, Amanda R; Haiduke, Roberto L A; da Silva, Albérico B F

    2015-10-01

    Accurate Gaussian basis sets for atoms from H to Ba were obtained by means of the generator coordinate Hartree-Fock (GCHF) method based on a polynomial expansion to discretize the Griffin-Wheeler-Hartree-Fock equations (GWHF). The discretization of the GWHF equations in this procedure is based on a mesh of points not equally distributed in contrast with the original GCHF method. The results of atomic Hartree-Fock energies demonstrate the capability of these polynomial expansions in designing compact and accurate basis sets to be used in molecular calculations and the maximum error found when compared to numerical values is only 0.788 mHartree for indium. Some test calculations with the B3LYP exchange-correlation functional for N2, F2, CO, NO, HF, and HCN show that total energies within 1.0 to 2.4 mHartree compared to the cc-pV5Z basis sets are attained with our contracted bases with a much smaller number of polarization functions (2p1d and 2d1f for hydrogen and heavier atoms, respectively). Other molecular calculations performed here are also in very good accordance with experimental and cc-pV5Z results. The most important point to be mentioned here is that our generator coordinate basis sets required only a tiny fraction of the computational time when compared to B3LYP/cc-pV5Z calculations.

  4. Generating ultrabroadband terahertz radiation based on the under-compression mode of velocity bunching

    SciTech Connect

    Wang, D.; Yan, L. X.; Du, Y. C.; Hua, J. F.; Du, Q.; Qian, H. J.; Lu, X. H.; Huang, W. H.; Chen, H. B.; Tang, C. X.

    2013-02-15

    We propose and analyze a scheme to generate enhanced ultrabroadband terahertz (THz) radiation through coherent transition radiation emitted by ultrashort electron beams based on a 10.5 m beamline at Tsinghua University. The proposed scheme involves the initial compression of the electron beam with a few hundred pC charges using a velocity bunching scheme (i.e., RF compression) in an under-compression mode instead of the usual critical-compression mode in order to maintain a positive energy chirp at the exit of the traveling wave accelerator. After a long drift segment, the particles in the tail catch up with the bunch head. More than 80% of the particles are distributed in a spike with an rms length less than 20 fs. Such beams correspond to an ultrabroadband coherent transition radiation (CTR) spectrum of 0.1 THz to 25 THz, with the single-pulse THz radiation energy of up to 50 {mu}J. The principle of CTR and under-compression mode of velocity bunching are introduced in this paper. And the ASTRA simulation parameters and the stability of the system are also discussed.

  5. TOMCAT - A code for numerical generation of boundary-fitted curvilinear coordinate systems on fields containing any number of arbitrary two-dimensional bodies

    NASA Technical Reports Server (NTRS)

    Thompson, J. F.; Thames, F. C.; Mastin, C. W.

    1977-01-01

    A method for automatic generation of boundary-fitted curvilinear coordinate systems, where the transformed coordinates are solutions of an elliptic differential system in the physical plane, and where the coordinate lines are coincident with all boundaries of a general multiply-connected, two-dimensional region containing any number of arbitrarily shaped bodies, and is described along with a suitable computer code for implementing the method. Any partial differential system can be solved on the boundary-fitted coordinate system by appropriate transformations. The transformed equations are approximated by finite differences and solved numerically in the transformed plane. All computations, whether for generating coordinate system or then solving the transformed equations, can be done on a rectangular field with square mesh with no interpolation required on the boundaries. The physical boundaries may even be time-dependent.

  6. Generators of nonclassical states by a combination of linear coupling of boson modes, Kerr nonlinearity, and strong linear losses

    SciTech Connect

    Shchesnovich, V. S.; Mogilevtsev, D.

    2011-07-15

    We show that the generators of quantum states of light can be built by employing the Kerr nonlinearity, a strong linear absorption or losses, and the linear coupling of optical modes. Our setup can be realized, for instance, with the use of the optical fiber technology. We consider in detail the simplest cases of three and four coupled modes, where a strongly lossy mode is linearly coupled to other linear and nonlinear modes. In the three-mode design, our scheme emulates the third-order nonlinear absorption, allowing for generation of the single-photon states, or two-photon absorption allowing the generation of the phase states. In the four-mode design, the scheme emulates a nonlocal absorption which produces an entangled state of two uncoupled modes. We also note that in the latter case and in the case of phase state generation the output state is in the linear mode, which prevents its subsequent degradation by strong losses accompanying a strong Kerr nonlinearity.

  7. Terahertz generation and detection using femtosecond mode-locked Yb-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Kong, Moon Sik; Kim, Ji Su; Han, Sang-Pil; Kim, Namje; Moon, Ki Won; Park, Kyung Hyun; Jeon, Min Yong

    2016-02-01

    We successfully demonstrate a THz generation using an ytterbium (Yb)-doped mode-locked femtosecond fiber laser and a home-made low-temperature grown (LTG) InGaAs Photoconductive antenna (PCA) module for THz Time-domain spectroscopy (TDS) systems. The Yb-doped fiber ring laser consists of a pump laser diode (PLD), a wavelength division multiplexer (WDM) coupler, a single-mode fiber (SMF), a 25 cm-long highly Yb-doped fiber, two collimators, two quarter wave plates (QWPs), a half-wave plate (HWP), a 10 nm broadband band pass filter, an isolator, and a polarizing beam splitter (PBS). In order to achieve the passively mode-locked optical short pulse, the nonlinear polarization rotation (NPR) effect is used. The achieved center wavelength and the 3 dB bandwidth of the modelocked fiber laser are 1.03 μm and ~ 15.6 nm, respectively. It has 175 fs duration after pulse compression with 66.2 MHz repetition rate. The average output power of mode-locked laser has more than 275 mW. The LTG-InGaAs PCA modules are used as the emitter and receiver in order to achieve the THz radiation. The PCA modules comprise a hyper-hemispherical Si lens and a log-spiral antenna-integrated LTG-InGaAs PCA chip electronically contacted on a printed circuit board (PCB). An excitation optical average pumping and probing power were ~ 6.3 mW and 5 mW, respectively. The free-space distance between the emitter and the receiver in the THz-TDS system was 70 mm. The spectrum of the THz radiation is achieved higher than 1.5 THz.

  8. Generation of propagating backward volume spin waves by phase-sensitive mode conversion in two-dimensional microstructures

    SciTech Connect

    Braecher, T.; Sebastian, T.; Pirro, P.; Westermann, J.; Laegel, B.; Hillebrands, B.; Van de Wiele, B.; Vansteenkiste, A.

    2013-04-01

    We present the generation of propagating backward volume (BV) spin waves in a T shaped Ni{sub 81}Fe{sub 19} microstructure. These waves are created from counterpropagating Damon Eshbach spin waves, which are excited using microstrip antennas. By employing Brillouin light scattering microscopy, we show how the phase relation between the counterpropagating waves determines the mode generated in the center of the structure, and prove its propagation inside the longitudinally magnetized part of the T shaped microstructure. This gives access to the effective generation of backward volume spin waves with full control over the generated transverse mode.

  9. Generation of propagating backward volume spin waves by phase-sensitive mode conversion in two-dimensional microstructures

    NASA Astrophysics Data System (ADS)

    Brächer, T.; Pirro, P.; Westermann, J.; Sebastian, T.; Lägel, B.; Van de Wiele, B.; Vansteenkiste, A.; Hillebrands, B.

    2013-04-01

    We present the generation of propagating backward volume (BV) spin waves in a T shaped Ni81Fe19 microstructure. These waves are created from counterpropagating Damon Eshbach spin waves, which are excited using microstrip antennas. By employing Brillouin light scattering microscopy, we show how the phase relation between the counterpropagating waves determines the mode generated in the center of the structure, and prove its propagation inside the longitudinally magnetized part of the T shaped microstructure. This gives access to the effective generation of backward volume spin waves with full control over the generated transverse mode.

  10. Three-dimensional adaptive grid generation for body-fitted coordinate system

    NASA Technical Reports Server (NTRS)

    Chen, S. C.

    1988-01-01

    This report describes a numerical method for generating 3-D grids for general configurations. The basic method involves the solution of a set of quasi-linear elliptic partial differential equations via pointwise relaxation with a local relaxation factor. It allows specification of the grid spacing off the boundary surfaces and the grid orthogonality at the boundary surfaces. It includes adaptive mechanisms to improve smoothness, orthogonality, and flow resolution in the grid interior.

  11. Generation of sub-100-fs pulses from a CW mode-locked chromium-doped forsterite laser

    NASA Technical Reports Server (NTRS)

    Seas, A.; Petricevic, V.; Alfano, R. R.

    1992-01-01

    Generation of femtosecond pulses from a continuous-wave mode-locked chromium-doped forsterite laser is reported. The forsterite laser was actively mode locked by using an acoustooptic modulator operating at 78 MHz with two Brewster high-dispersion glass prisms for intracavity chirp compensation. Transform-limited sub-100-fs pulses were routinely generated in the TEM(00) mode with 85 mW of continuous power (with 1 percent output coupler), tunable over 1230-1280 nm. The shortest pulses measured had a 60-fs pulse width.

  12. Entanglement and nonclassicality in four-mode Gaussian states generated via parametric down-conversion and frequency up-conversion

    PubMed Central

    Arkhipov, Ievgen I.; Peřina Jr., Jan; Haderka, Ondřej; Allevi, Alessia; Bondani, Maria

    2016-01-01

    Multipartite entanglement and nonclassicality of four-mode Gaussian states generated in two simultaneous nonlinear processes involving parametric down-conversion and frequency up-conversion are analyzed assuming the vacuum as the initial state. Suitable conditions for the generation of highly entangled states are found. Transfer of the entanglement from the down-converted modes into the up-converted ones is also suggested. The analysis of the whole set of states reveals that sub-shot-noise intensity correlations between the equally-populated down-converted modes, as well as the equally-populated up-converted modes, uniquely identify entangled states. They represent a powerful entanglement identifier also in other cases with arbitrarily populated modes. PMID:27658508

  13. CONTROL OF LASER RADIATION PARAMETERS: Generation of polarisation-nonuniform modes in a high-power CO2 laser

    NASA Astrophysics Data System (ADS)

    Niz'ev, Vladimir G.; Yakunin, V. P.; Turkin, N. G.

    2009-06-01

    A method describing radially and azimuthally polarised laser modes is presented, which is devoid of intrinsic contradictions and unjustified restrictions. The solutions of the wave equation found in the paper satisfy Maxwell's equation bigtriangledownE = 0. This allowed the calculation of all the components of the fields of such modes, including the longitudinal one. Expressions for tight focusing of radially and azimuthally polarised modes are obtained in the Debye approximation. The methods of intracavity generation of such modes in a high-power industrial CO2 laser are experimentally realised and methods of mutual transformation of these modes outside the cavity are developed. The intracavity generation of azimuthally polarised modes was achieved by using as a rear highly reflecting mirror either V-shaped axicons or metal diffraction mirrors with the relief period comparable to the wavelength. Radially polarised radiation was generated by using diffraction mirrors with the relief period of the order of two wavelengths. The polarisation-nonuniform TEM01* and TEM11* modes of power up to 1.8 kW are generated for the first time. In this case, the degree of polarisation was close to 100% within the entire radiation power range both in the near- and far-field zones. By using two half-wave phase shifters, the azimuthally polarised radiation is transformed to radially polarised radiation and vice versa, the energy efficiency of this transformation being 92%. These results open up the possibility for industrial applications of such radiation.

  14. Connection and coordination: the interplay between architecture and dynamics in evolved model pattern generators.

    PubMed

    Psujek, Sean; Ames, Jeffrey; Beer, Randall D

    2006-03-01

    We undertake a systematic study of the role of neural architecture in shaping the dynamics of evolved model pattern generators for a walking task. First, we consider the minimum number of connections necessary to achieve high performance on this task. Next, we identify architectural motifs associated with high fitness. We then examine how high-fitness architectures differ in their ability to evolve. Finally, we demonstrate the existence of distinct parameter subgroups in some architectures and show that these subgroups are characterized by differences in neuron excitabilities and connection signs.

  15. Photoactivated processes in optical fibers: generation and conversion mechanisms of twofold coordinated Si and Ge atoms.

    PubMed

    Giacomazzi, Luigi; Martin-Samos, Layla; Boukenter, Aziz; Ouerdane, Youcef; Girard, Sylvain; Alessi, Antonino; Richard, Nicolas; de Gironcoli, Stefano

    2017-03-27

    In this work we present an extensive investigation of nanoscale physical phenomena related to oxygen-deficient centers (ODC) in silica and Ge-doped silica by means of first-principles calculations, including nudged-elastic band (NEB), electron paramagnetic resonance (EPR) parameters calculations, and many-body perturbation theory (GW and Bethe-Salpeter Equation) techniques. We show that by neutralizing positively charged oxygen monovacancies we can obtain model structures of twofold Si and Ge defects of which the calculated absorption spectra and singlet-to-triplet transitions are in excellent agreement with the experimental optical absorption and photo-luminescence data. In particular we provide an exhaustive analysis of the main exciton peaks related to the presence of twofold defects including long-range correlation effects. By calculating the reaction pathways and energy barriers necessary for the interconversion, we advance a double precursory origin of the E'α and Ge(2) centers as due to the ionization of neutral oxygen monovacancies (Si-Si and Ge-Si dimers) and as due to the ionization of twofold Si and Ge defects. Furthermore two distinct structural conversion mechanisms are found to occur between the neutral oxygen monovacancy and the twofold Si (and Ge) atom configurations. Such conversion mechanisms allow to explain the radiation induced generation of the ODC(II) centers, their photobleaching, and also their generation during the drawing of optical fibers.

  16. Unprecedented coordination modes and demetalation pathways for unbridged polyenyl ligands. Ruthenium eta1,eta4-cycloheptadienyl complexes from allyl/alkyne cycloaddition.

    PubMed

    Older, Christina M; McDonald, Robert; Stryker, Jeffrey M

    2005-10-19

    Cationic (eta6-hexamethylbenzene)ruthenium(II) mediates the [3 + 2 + 2] cycloaddition of allyl and alkyne ligands, leading to the unexpected isolation of eta1,eta4-cycloheptadienyl complexes, an unprecedented coordination mode for transition metal complexes of simple organic rings. The nonconjugated, eta1,eta4-coordinated complex is obtained as the kinetic reaction product from treatment of the unsubstituted allyl complex with excess ethyne; this complex rearranges slowly at 80 degrees C to the thermodynamically more stable conjugated eta5-cycloheptadienyl isomer. The eta1,eta4-coordinated isomer is fluxional at room temperature, undergoing rapid and reversible equilibration with a cycloheptatriene hydride intermediate via facile beta-hydride elimination/reinsertion. The reinsertion process is remarkably regioselective, returning the nonconjugated eta1,eta4-cycloheptadienyl isomer exclusively at room temperature. For reactions incorporating dimethylacetylene dicarboxylate (DMAD) as one or both of the alkyne components, eta1,eta4-coordination appears to be both kinetically and thermodynamically favored, despite undergoing equilibration among all possible eta1,eta4-cycloheptadienyl and cycloheptatriene hydride isomers prior to arriving at one observed eta1,eta4-isomer. For this series, no isomerization to eta5-coordination is observed even upon prolonged heating. In contrast, the cyclization incorporating both DMAD and phenylacetylene proceeds directly to the eta5-cycloheptadienyl isomer at or below room temperature, indicating that eta5-coordination remains energetically accessible to this system. The DMAD-based cyclization reactions produce structurally diverse minor byproducts, including both eta1,eta4-methanocyclohexadiene and acyclic eta3,eta2-heptadienyl isomers, which have been isolated and rigorously characterized. The unusual eta1,eta4-coordination of the seven-membered ring leads to unique new organic products upon oxidative demetalation by iodinolysis

  17. High-order harmonic generation of CO2 with different vibrational modes in an intense laser field

    NASA Astrophysics Data System (ADS)

    Du, Hui; Zhang, Hong-Dan; Zhang, Jun; Liu, Hai-Feng; Pan, Xue-Fei; Guo, Jing; Liu, Xue-Shen

    2016-11-01

    We apply the strong-field Lewenstein model to demonstrate the high-order harmonic generation of CO2 with three vibrational modes (balance vibration, bending vibration, and stretching vibration) driven by an intense laser field. The results show that the intensity of harmonic spectra is sensitive to molecular vibrational modes, and the high harmonic efficiency with stretching vibrational mode is the strongest. The underlying physical mechanism of the harmonic emission can be well explained by the corresponding ionization yield and the time-frequency analysis. Finally, we demonstrate the attosecond pulse generation with different vibrational modes and an isolated attosecond pulse with a duration of about 112 as is generated. Project supported by the National Natural Science Foundation of China (Grant Nos. 61575077, 11271158, and 11574117).

  18. Evidence of a central pattern generator regulating spermathecal muscle activity in Locusta migratoria and its coordination with oviposition.

    PubMed

    da Silva, Rosa; Lange, Angela B

    2011-03-01

    Electrophysiological recordings were conducted to determine the control of spermathecal contractions during oviposition of interrupted egg-laying locusts, Locusta migratoria. Following transection of the central nervous system below the metathoracic ganglion, rhythmic patterned bursting was detected by extracellular recordings of the nerve N2B2 that innervates the muscles of the spermatheca. Subsequent transections at more posterior regions of the ventral nerve cord revealed more robust rhythmic bursting in N2B2. This rhythmic bursting pattern was found to be coordinated with bursting in the ventral opener nerve (N2B1) that innervates the ventral opener muscle. This muscle controls the ventral ovipositor valves. Electromyographic recordings from the spermathecal muscle and ventral opener muscle confirmed a rhythmic bursting pattern resulting in an increase in muscle activity. Taken together, the results indicate that there is probably a central pattern generator (CPG), which is regulated by descending inhibition, that controls the spermathecal muscle activity. This CPG appears to be located within the VIIth and VIIIth abdominal ganglia, and was found to integrate with the CPG that regulates oviposition digging in locusts. These results provide further insight into the intricate coordination and control of reproductive tissues underlying reproductive behaviours in locusts.

  19. Analysis of threshold conditions for generation of a closed mode in a Fabry-Perot semiconductor laser

    SciTech Connect

    Slipchenko, S. O. Podoskin, A. A.; Pikhtin, N. A.; Sokolova, Z. N.; Leshko, A. Y.; Tarasov, I. S.

    2011-05-15

    Threshold conditions for generation of a closed mode in the crystal of the Fabry-Perot semiconductor laser with a quantum-well active region are analyzed. It is found that main parameters affecting the closed mode lasing threshold for the chosen laser heterostructure are as follows: the optical loss in the passive region, the optical confinement factor of the closed mode in the gain region, and material gain detuning. The relations defining the threshold conditions for closed mode lasing in terms of optical and geometrical characteristics of the semiconductor laser are derived. It is shown that the threshold conditions can be satisfied at a lower material gain in comparison with the Fabry-Perot cavity mode due to zero output loss for the closed mode.

  20. Laser beam shaping for enhanced Zero-Group Velocity Lamb modes generation.

    PubMed

    Bruno, François; Laurent, Jérôme; Jehanno, Paul; Royer, Daniel; Prada, Claire

    2016-10-01

    Optimization of Lamb modes induced by laser can be achieved by adjusting the spatial source distribution to the mode wavelength (λ). The excitability of Zero-Group Velocity (ZGV) resonances in isotropic plates is investigated both theoretically and experimentally for axially symmetric sources. Optimal parameters and amplitude gains are derived analytically for spot and annular sources of either Gaussian or rectangular energy profiles. For a Gaussian spot source, the optimal radius is found to be λZGV/π. Annular sources increase the amplitude by at least a factor of 3 compared to the optimal Gaussian source. Rectangular energy profiles provide higher gain than Gaussian ones. These predictions are confirmed by semi-analytical simulation of the thermoelastic generation of Lamb waves, including the effect of material attenuation. Experimentally, Gaussian ring sources of controlled width and radius are produced with an axicon-lens system. Measured optimal geometric parameters obtained for Gaussian and annular beams are in good agreement with theoretical predictions. A ZGV resonance amplification factor of 2.1 is obtained with the Gaussian ring. Such source should facilitate the inspection of highly attenuating plates made of low ablation threshold materials like composites.

  1. Laser beam shaping for enhanced Zero-Group Velocity Lamb modes generation

    NASA Astrophysics Data System (ADS)

    Bruno, François; Laurent, Jérôme; Jehanno, Paul; Royer, Daniel; Prada, Claire

    2016-10-01

    Optimization of Lamb modes induced by laser can be achieved by adjusting the spatial source distribution to the mode wavelength ($\\lambda$). The excitability of Zero-Group Velocity (ZGV) resonances in isotropic plates is investigated both theoretically and experimentally for axially symmetric sources. Optimal parameters and amplitude gains are derived analytically for spot and annular sources of either Gaussian or rectangular energy profiles. For a Gaussian spot source, the optimal radius is found to be $\\lambda_{ZGV}/\\pi$. Annular sources increase the amplitude by at least a factor of 3 compared to the optimal Gaussian source. Rectangular energy profiles provide higher gain than Gaussian ones. These predictions are confirmed by semi-analytical simulation of the thermoelastic generation of Lamb waves, including the effect of material attenuation. Experimentally, Gaussian ring sources of controlled width and radius are produced with an axicon-lens system. Measured optimal geometric parameters obtained for Gaussian and annular beams are in good agreement with theoretical predictions. A ZGV resonance amplification factor of 2.1 is obtained with the Gaussian ring. Such source should facilitate the inspection of highly attenuating plates made of low ablation threshold materials like composites.

  2. Non-thermal Plasmas Around Black Holes, New Configurations, Magnetic Field Generation and Relevant Collective Modes

    NASA Astrophysics Data System (ADS)

    Asgari-Targhi, M.; Coppi, B.

    2016-10-01

    The radiation emission from Shining Black Holes is most frequently observed to have non-thermal features. It is therefore appropriate to consider relevant collective processes of plasmas surrounding black holes that contain high energy particles with non-thermal distributions in momentum space. For simplicity we use a fluid description considering the case where significant temperature anisotropies are present. These anisotropies are shown to have a critical influence on: a) the existence and characteristics of stationary plasma and field configurations; b) the excitation of magneto-gravitational modes driven by temperature anisotropies and differential rotation; c) the generation of magnetic fields over macroscopic scale distances; d) the outward transport of angular momentum. Sponsored in part by the U.S. D.O.E.

  3. Theory of Fine-scale Zonal Flow Generation From Trapped Electron Mode Turbulence

    SciTech Connect

    Lu Wang and T.S. Hahm

    2009-06-11

    Most existing zonal flow generation theory has been developed with a usual assumption of qrρθ¡ << 1 (qr is the radial wave number of zonal flow, and ρθ¡ is the ion poloidal gyrora- dius). However, recent nonlinear gyrokinetic simulations of trapped electron mode (TEM) turbulence exhibit a relatively short radial scale of the zonal flows with qrρθ¡ ~ 1 [Z. Lin et al., IAEA-CN/TH/P2-8 (2006); D. Ernst et al., Phys. Plasmas 16, 055906 (2009)]. This work reports an extension of zonal flow growth calculation to this short wavelength regime via the wave kinetics approach. A generalized expression for the polarization shielding for arbitrary radial wavelength [Lu Wang and T.S. Hahm, to appear in Phys. Plasmas (2009)] which extends the Rosenbluth-Hinton formula in the long wavelength limit is applied.

  4. Optical sum-frequency generation in a whispering-gallery-mode resonator

    NASA Astrophysics Data System (ADS)

    Strekalov, Dmitry V.; Kowligy, Abijith S.; Huang, Yu-Ping; Kumar, Prem

    2014-05-01

    We demonstrate sum-frequency generation between a telecom wavelength and the Rb D2 line, achieved through natural phase matching in a nonlinear whispering gallery mode resonator. Due to the strong optical field confinement and ultra high Q of the cavity, the process saturates already at sub-mW pump peak power, at least two orders of magnitude lower than in existing waveguide-based devices. The experimental data are in agreement with the nonlinear dynamics and phase matching theory based on spherical geometry. Our experimental and theoretical results point toward a new platform for manipulating the color and quantum states of light waves for applications such as atomic memory based quantum networking and logic operations with optical signals.

  5. Heralded generation of single photons entangled in multiple temporal modes with controllable waveforms

    NASA Astrophysics Data System (ADS)

    Gogyan, A.; Sisakyan, N.; Akhmedzhanov, R.; Malakyan, Yu

    2014-11-01

    Time-bin entangled single-photons are highly demanded for long distance quantum communication. We propose a heralded source of tunable narrowband single photons entangled in well-separated multiple temporal modes (time bins) with controllable amplitudes. The detection of a single Stokes photon generated in a cold atomic ensemble via Raman scattering of a weak write pulse heralds the preparation of one spin excitation stored within the atomic medium. A train of read laser pulses deterministically converts the atomic excitation into a single anti-Stokes photon delocalized in multi-time-bins. The waveforms of bins are well-controlled by the read pulse parameters. A scheme to measure the phase coherence across all time bins is suggested.

  6. Generation and entanglement of multi-dimensional multi-mode coherent fields in cavity QED

    NASA Astrophysics Data System (ADS)

    Maleki, Y.

    2016-11-01

    We introduce generalized multi-mode superposition of multi-dimensional coherent field states and propose a generation scheme of such states in a cavity QED scenario. An appropriate encoding of information on these states is employed, which maps the states to the Hilbert space of some multi-qudit states. The entanglement of these states is characterized based on such proper encodings. A detailed study of entanglement in general multi-qudit coherent states is presented, and in addition to establishing some explicit expressions for quantifying entanglement of such systems, several important features of entanglement in these system states are exposed. Furthermore, the effects of both cavity decay and channel noise on these system states are studied and their properties are illustrated.

  7. Dual-polarization and dual-mode orbital angular momentum radio vortex beam generated by using reflective metasurface

    NASA Astrophysics Data System (ADS)

    Yu, Shixing; Li, Long; Shi, Guangming

    2016-08-01

    A metasurface, which is composed of printed cross-dipole elements with different arm lengths, is designed, fabricated, and experimentally demonstrated to generate orbital angular momentum (OAM) vortex waves of dual polarizations and dual modes in the radio frequency domain simultaneously. The prototype of a practical metasurface is fabricated and measured to validate the results of theoretical analysis and design at 5.8 GHz. Numerical and experimental results verify that vortex waves with dual OAM modes and dual polarizations can be flexibly generated by using a reflective metasurface. The proposed method paves a way to generate diverse OAM vortex waves for radio frequency and microwave wireless communication applications.

  8. Thiodiacetate-manganese chemistry with N ligands: unique control of the supramolecular arrangement over the metal coordination mode.

    PubMed

    Grirrane, Abdessamad; Pastor, Antonio; Galindo, Agustín; Alvarez, Eleuterio; Mealli, Carlo; Ienco, Andrea; Orlandini, Annabella; Rosa, Patrick; Caneschi, Andrea; Barra, Anne-Laure; Sanz, Javier Fernández

    2011-09-12

    Compounds based on the Mn-tda unit (tda=S(CH(2)COO)(2)(-2) ) and N co-ligands have been analyzed in terms of structural, spectroscopic, magnetic properties and DFT calculations. The precursors [Mn(tda)(H(2)O)](n) (1) and [Mn(tda)(H(2)O)(3)]·H(2)O (2) have been characterized by powder and X-ray diffraction, respectively. Their derivatives with bipyridyl-type ligands have formulas [Mn(tda)(bipy)](n) (3), [{Mn(N-N)}(2)(μ-H(2)O)(μ-tda)(2)](n) (N-N=4,4'-Me(2)bipy (4), 5,5'-Me(2)bipy, (5)) and [Mn(tda){(MeO)(2)bipy}·2H(2)O](n) (6). Depending on the presence/position of substituents at bipy, the supramolecular arrangement can affect the metal coordination type. While all the complexes consist of 1D coordination polymers, only 3 has a copper-acetate core with local trigonal prismatic metal coordination. The presence of substituents in 4-6, together with water co-ligands, reduces the supramolecular interactions and typical octahedral Mn(II) ions are observed. The unicity of 3 is also supported by magnetic studies and by DFT calculations, which confirm that the unusual Mn coordination is a consequence of extended noncovalent interactions (π-π stacking) between bipy ligands. Moreover, 3 is an example of broken paradigm for supramolecular chemistry. In fact, the desired stereochemical properties are achieved by using rigid metal building blocks, whereas in 3 the accumulation of weak noncovalent interactions controls the metal geometry. Other N co-ligands have also been reacted with 1 to give the compounds [Mn(tda)(phen)](2)·6H(2)O (7) (phen=1,10-phenanthroline), [Mn(tda)(terpy)](n) (8) (terpy=2,2':6,2''-terpyridine), [Mn(tda)(pyterpy)](n) (9) (pyterpy=4'-(4-pyridyl)-2,2':6,2''-terpyridine), [Mn(tda)(tpt)(H(2)O)]·2H(2)O (10) and [Mn(tda)(tpt)(H(2)O)](2)·2H(2)O (11) (tpt=2,4,6-tris(2-pyridyl)-1,3,5-triazine). Their identified mono-, bi- or polynuclear structures clearly indicate that hydrogen bonding is variously competitive with π-π stacking.

  9. High Harmonic Generation XUV Spectroscopy for Studying Ultrafast Photophysics of Coordination Complexes

    NASA Astrophysics Data System (ADS)

    Ryland, Elizabeth S.; Lin, Ming-Fu; Verkamp, Max A.; Vura-Weis, Josh

    2016-06-01

    Extreme ultraviolet (XUV) spectroscopy is an inner shell technique that probes the M2,3-edge excitation of atoms. Absorption of the XUV photon causes a 3p→3d transition, the energy and shape of which is directly related to the element and ligand environment. This technique is thus element-, oxidation state-, spin state-, and ligand field specific. A process called high-harmonic generation (HHG) enables the production of ultrashort (≈20fs) pulses of collimated XUV photons in a tabletop instrument. This allows transient XUV spectroscopy to be conducted as an in-lab experiment, where it was previously only possible at accelerator-based light sources. Additionally, ultrashort pulses provide the capability for unprecedented time resolution (≈70fs IRF). This technique has the capacity to serve a pivotal role in the study of electron and energy transfer processes in materials and chemical biology. I will present the XUV transient absorption instrument we have built over the past two years, along with preliminary data and simulations of the M2,3-edge absorption data of a battery of small inorganic molecules to demonstrate the high specificity of this ultrafast tabletop technique.

  10. Up to 400 GHz burst-mode pulse generation from a hybrid harmonic mode-locked Er-doped fibre laser

    NASA Astrophysics Data System (ADS)

    Wang, Sheng-Min; Lai, Yinchieh

    2017-02-01

    By inserting a birefringence filter with FSR  =  100 GHz inside a hybrid mode-locked Er-doped fibre laser, we successfully generate ps to sub-ps optical burst pulses with the intra-burst pulse rate up to 400 GHz. Multiplication of the intra-burst pulse rate is attributed to a new effect analogous to rational harmonic mode-locking, which occurs due to the relative alignment of the cavity harmonic frequencies, the external phase modulation induced frequencies, and the filter-selected frequencies.

  11. Mode matching in multiresonant plasmonic nanoantennas for enhanced second harmonic generation.

    PubMed

    Celebrano, Michele; Wu, Xiaofei; Baselli, Milena; Großmann, Swen; Biagioni, Paolo; Locatelli, Andrea; De Angelis, Costantino; Cerullo, Giulio; Osellame, Roberto; Hecht, Bert; Duò, Lamberto; Ciccacci, Franco; Finazzi, Marco

    2015-05-01

    Boosting nonlinear frequency conversion in extremely confined volumes remains a challenge in nano-optics research, but can enable applications in nanomedicine, photocatalysis and background-free biosensing. To obtain brighter nonlinear nanoscale sources, approaches that enhance the electromagnetic field intensity and counter the lack of phase matching in nanoplasmonic systems are often employed. However, the high degree of symmetry in the crystalline structure of plasmonic materials (metals in particular) and in nanoantenna designs strongly quenches second harmonic generation. Here, we describe doubly-resonant single-crystalline gold nanostructures with no axial symmetry displaying spatial mode overlap at both the excitation and second harmonic wavelengths. The combination of these features allows the attainment of a nonlinear coefficient for second harmonic generation of ∼5 × 10(-10) W(-1), enabling a second harmonic photon yield higher than 3 × 10(6) photons per second. Theoretical estimations point toward the use of our nonlinear plasmonic nanoantennas as efficient platforms for label-free molecular sensing.

  12. Ion beam generated modes in the lower hybrid frequency range in a laboratory magnetoplasma

    NASA Astrophysics Data System (ADS)

    van Compernolle, Bart; Tripathi, Shreekrishna; Gekelman, Walter; Pribyl, Patrick

    2013-10-01

    The interaction of a fast ion beam with a low β plasma has been studied in the laboratory. Experiments were performed at the LArge Plasma Device (LAPD) at UCLA. The experiments were done in a Helium plasma (n ~=1012cm-3 , B0 = 1000 G - 1800 G, fpe /fce ~= 1 - 5 , Te ~= 4eV , vte <generation was studied for various plasma parameters, as well as for different beam energies and pitch angles. The waves were measured with 3-axis electric and magnetic probes. Detailed measurements of the 2D perpendicular mode structure will be shown. Progress on a theoretical framework of the wave generation by the ion beam will be presented along with comparisons to the measured wave properties. The work was performed at the LArge Plasma Device at the Basic Plasma Science Facility (BaPSF) at UCLA, funded by DOE/NSF.

  13. Hybrid Wing Body Shielding Studies Using an Ultrasonic Configurable Fan Artificial Noise Source Generating Simple Modes

    NASA Technical Reports Server (NTRS)

    Sutliff, Daniel, L.; Brown, Clifford, A.; Walker, Bruce, E.

    2012-01-01

    An Ultrasonic Configurable Fan Artificial Noise Source (UCFANS) was designed, built, and tested in support of the Langley Research Center s 14- by 22-Foot wind tunnel test of the Hybrid Wing Body (HWB) full three-dimensional 5.8 percent scale model. The UCFANS is a 5.8 percent rapid prototype scale model of a high-bypass turbofan engine that can generate the tonal signature of candidate engines using artificial sources (no flow). The purpose of the test was to provide an estimate of the acoustic shielding benefits possible from mounting the engine on the upper surface of an HWB aircraft and to provide a database for shielding code validation. A range of frequencies, and a parametric study of modes were generated from exhaust and inlet nacelle configurations. Radiated acoustic data were acquired from a traversing linear array of 13 microphones, spanning 36 in. Two planes perpendicular to the axis of the nacelle (in its 0 orientation) and three planes parallel were acquired from the array sweep. In each plane the linear array traversed five sweeps, for a total span of 160 in. acquired. The resolution of the sweep is variable, so that points closer to the model are taken at a higher resolution. Contour plots of Sound Pressure Level, and integrated Power Levels are presented in this paper; as well as the in-duct modal structure.

  14. Optimal mode transformations for linear-optical cluster-state generation

    SciTech Connect

    Uskov, Dmitry B.; Lougovski, Pavel; Alsing, Paul M.; Fanto, Michael L.; Kaplan, Lev; Smith, Amos Matthew

    2015-06-15

    In this paper, we analyze the generation of linear-optical cluster states (LOCSs) via sequential addition of one and two qubits. Existing approaches employ the stochastic linear-optical two-qubit controlled-Z (CZ) gate with success rate of 1/9 per operation. The question of optimality of the CZ gate with respect to LOCS generation has remained open. We report that there are alternative schemes to the CZ gate that are exponentially more efficient and show that sequential LOCS growth is indeed globally optimal. We find that the optimal cluster growth operation is a state transformation on a subspace of the full Hilbert space. Finally, we show that the maximal success rate of postselected entangling n photonic qubits or m Bell pairs into a cluster is (1/2)n-1 and (1/4)m-1, respectively, with no ancilla photons, and we give an explicit optical description of the optimal mode transformations.

  15. Optimally Coherent Kerr Combs Generated with Crystalline Whispering Gallery Mode Resonators for Ultrahigh Capacity Fiber Communications

    NASA Astrophysics Data System (ADS)

    Pfeifle, Joerg; Coillet, Aurélien; Henriet, Rémi; Saleh, Khaldoun; Schindler, Philipp; Weimann, Claudius; Freude, Wolfgang; Balakireva, Irina V.; Larger, Laurent; Koos, Christian; Chembo, Yanne K.

    2015-03-01

    Optical Kerr frequency combs are known to be effective coherent multiwavelength sources for ultrahigh capacity fiber communications. These combs are the frequency-domain counterparts of a wide variety of spatiotemporal dissipative structures, such as cavity solitons, chaos, or Turing patterns (rolls). In this Letter, we demonstrate that Turing patterns, which correspond to the so-called primary combs in the spectral domain, are optimally coherent in the sense that for the same pump power they provide the most robust carriers for coherent data transmission in fiber communications using advanced modulation formats. Our model is based on a stochastic Lugiato-Lefever equation which accounts for laser pump frequency jitter and amplified spontaneous emission noise induced by the erbium-doped fiber amplifier. Using crystalline whispering-gallery-mode resonators with quality factor Q ˜109 for the comb generation, we show that when the noise is accounted for, the coherence of a primary comb is significantly higher than the coherence of their solitonic or chaotic counterparts for the same pump power. In order to confirm this theoretical finding, we perform an optical fiber transmission experiment using advanced modulation formats, and we show that the coherence of the primary comb is high enough to enable data transmission of up to 144 Gbit /s per comb line, the highest value achieved with a Kerr comb so far. This performance evidences that compact crystalline photonic systems have the potential to play a key role in a new generation of coherent fiber communication networks, alongside fully integrated systems.

  16. Enhanced Actuation Performance and Reduced Heat Generation in Shear-Bending Mode Actuator at High Temperature.

    PubMed

    Chen, Jianguo; Liu, Guoxi; Cheng, Jinrong; Dong, Shuxiang

    2016-08-01

    The actuation performance, strain hysteresis, and heat generation of the shear-bending mode actuators based on soft and hard BiScO3-PbTiO3 (BS-PT) ceramics were investigated under different thermal (from room temperature to 300 °C) and electrical loadings (from 2 to 10 kV/cm and from 1 to 1000 Hz). The actuator based on both soft and hard BS-PT ceramics worked stably at the temperature as high as 300 °C. The maximum working temperature of this shear-bending actuators is 150 °C higher than those of the traditional piezoelectric actuators based on commercial Pb(Zr, Ti)O3 materials. Furthermore, although the piezoelectric properties of soft-type ceramics based on BS-PT ceramics were superior to those of hard ceramics, the maximum displacement of the actuator based on hard ceramics was larger than that fabricated by soft ceramics at high temperature. The maximum displacement of the actuator based on hard ceramics was [Formula: see text] under an applied electric field of 10 kV/cm at 300 °C. The strain hysteresis and heat generation of the actuator based on hard ceramics was smaller than those of the actuator based on soft ceramics in the wide temperature range. These results indicated that the shear-bending actuator based on hard piezoelectric ceramics was more suitable for high-temperature piezoelectric applications.

  17. Optimal mode transformations for linear-optical cluster-state generation

    DOE PAGES

    Uskov, Dmitry B.; Lougovski, Pavel; Alsing, Paul M.; ...

    2015-06-15

    In this paper, we analyze the generation of linear-optical cluster states (LOCSs) via sequential addition of one and two qubits. Existing approaches employ the stochastic linear-optical two-qubit controlled-Z (CZ) gate with success rate of 1/9 per operation. The question of optimality of the CZ gate with respect to LOCS generation has remained open. We report that there are alternative schemes to the CZ gate that are exponentially more efficient and show that sequential LOCS growth is indeed globally optimal. We find that the optimal cluster growth operation is a state transformation on a subspace of the full Hilbert space. Finally,more » we show that the maximal success rate of postselected entangling n photonic qubits or m Bell pairs into a cluster is (1/2)n-1 and (1/4)m-1, respectively, with no ancilla photons, and we give an explicit optical description of the optimal mode transformations.« less

  18. Mode matching in multiresonant plasmonic nanoantennas for enhanced second harmonic generation

    NASA Astrophysics Data System (ADS)

    Celebrano, Michele; Wu, Xiaofei; Baselli, Milena; Großmann, Swen; Biagioni, Paolo; Locatelli, Andrea; de Angelis, Costantino; Cerullo, Giulio; Osellame, Roberto; Hecht, Bert; Duò, Lamberto; Ciccacci, Franco; Finazzi, Marco

    2015-05-01

    Boosting nonlinear frequency conversion in extremely confined volumes remains a challenge in nano-optics research, but can enable applications in nanomedicine, photocatalysis and background-free biosensing. To obtain brighter nonlinear nanoscale sources, approaches that enhance the electromagnetic field intensity and counter the lack of phase matching in nanoplasmonic systems are often employed. However, the high degree of symmetry in the crystalline structure of plasmonic materials (metals in particular) and in nanoantenna designs strongly quenches second harmonic generation. Here, we describe doubly-resonant single-crystalline gold nanostructures with no axial symmetry displaying spatial mode overlap at both the excitation and second harmonic wavelengths. The combination of these features allows the attainment of a nonlinear coefficient for second harmonic generation of ˜5 × 10-10 W-1, enabling a second harmonic photon yield higher than 3 × 106 photons per second. Theoretical estimations point toward the use of our nonlinear plasmonic nanoantennas as efficient platforms for label-free molecular sensing.

  19. Dispersion-Tolerant Multiple WDM Channel Millimeter-Wave Signal Generation Using a Single Monolithic Mode-Locked Semiconductor Laser

    NASA Astrophysics Data System (ADS)

    Attygalle, M.; Lim, C.; Nirmalathas, A.

    2005-01-01

    This paper presents a scheme by which multiple wavelength-division-multiplexed millimeter-wave (mm-wave) signals in the range of 30 GHz can be generated from a single monolithic semiconductor laser for applications in optically fed mm-wave networks or fiber radio networks. The mm-wave signals are generated using dual optical modes separated by a mm-wave frequency, obtained from spectrum slicing the output from a stable multimode hybrid mode-locked semiconductor laser. In this scheme, self-heterodyne detection at a high-speed photodetector achieves the photonic upconversion of low-data-rate signals to mm-wave frequencies without the need for electronic mixing. Experimental results show the generation of up to 14 WDM channels using a single laser. The phase noise of electrical signals generated by photonic upconversion of these signals is less than -94 dBc/Hz at 100-kHz offset frequency across the wavelengths. Also presented is the transmission of 155-Mb/s binary-phase-shift-keyed data signals at 30-GHz frequency over 10 km of single-mode fiber at different wavelengths using dual-mode signals. The results confirm that a bit-error rate of 10-^9 can be easily achieved. The dispersion tolerance of the dual-mode signals is evaluated using simulation and an analytical model and compared with other mm-wave signal generation techniques.

  20. A benzimidazole functionalised DO3A chelator showing pH switchable coordination modes with lanthanide ions.

    PubMed

    Fisher, Christopher M; Fuller, Euan; Burke, Benjamin P; Mogilireddy, Vijetha; Pope, Simon J A; Sparke, Amanda E; Déchamps-Olivier, Isabelle; Cadiou, Cyril; Chuburu, Françoise; Faulkner, Stephen; Archibald, Stephen J

    2014-07-07

    The synthesis of a new macrocyclic chelator incorporating a benzimidazole heterocycle is reported. Lanthanide complexes with macrocyclic chelators based on 1,4,7,10-tetra(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DOTA) and 1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO3A) are of interest in luminescent, radiopharmaceutical and magnetic resonance (MR) biomedical imaging applications. The benzimidazole DO3A chelator allows for sensitisation of europium(iii), terbium(iii) and ytterbium(iii) luminescence by the heterocycle and also shows a pH dependent coordination change due to protonation of the chelator (pKa = 4.1 for the europium(iii) complex). The thermodynamic stability of the complexes has been investigated by potentiometric titration with the gadolinium(iii) complex showing significantly higher stability than the zinc(ii) complex, where log βZnLH = 28.1 and log βGdLH = 32.1.

  1. Analyses of Longitudinal Mode Combustion Instability in J-2X Gas Generator Development

    NASA Technical Reports Server (NTRS)

    Hulka, J. R.; Protz, C. S.; Casiano, M. J.; Kenny, R. J.

    2011-01-01

    The National Aeronautics and Space Administration (NASA) and Pratt & Whitney Rocketdyne are developing a liquid oxygen/liquid hydrogen rocket engine for future upper stage and trans-lunar applications. This engine, designated the J-2X, is a higher pressure, higher thrust variant of the Apollo-era J-2 engine. The contract for development was let to Pratt & Whitney Rocketdyne in 2006. Over the past several years, development of the gas generator for the J-2X engine has progressed through a variety of workhorse injector, chamber, and feed system configurations on the component test stand at the NASA Marshall Space Flight Center (MSFC). Several of the initial configurations resulted in combustion instability of the workhorse gas generator assembly at a frequency near the first longitudinal mode of the combustion chamber. In this paper, several aspects of these combustion instabilities are discussed, including injector, combustion chamber, feed system, and nozzle influences. To ensure elimination of the instabilities at the engine level, and to understand the stability margin, the gas generator system has been modeled at the NASA MSFC with two techniques, the Rocket Combustor Interaction Design and Analysis (ROCCID) code and a lumped-parameter MATLAB(TradeMark) model created as an alternative calculation to the ROCCID methodology. To correctly predict the instability characteristics of all the chamber and injector geometries and test conditions as a whole, several inputs to the submodels in ROCCID and the MATLAB(TradeMark) model were modified. Extensive sensitivity calculations were conducted to determine how to model and anchor a lumped-parameter injector response, and finite-element and acoustic analyses were conducted on several complicated combustion chamber geometries to determine how to model and anchor the chamber response. These modifications and their ramification for future stability analyses of this type are discussed.

  2. Is the Linear Mode Conversion Theory Viable for Generating Kilometric Continuum?

    NASA Technical Reports Server (NTRS)

    Boardsen, Scott A.; Green, James L.; Hashimoto, K.; Gallagher, Dennis L.; Webb, P. A.

    2006-01-01

    Kilometric Continuum (KC) usually exhibits a complicated banded radiation pattern observed in frequency time spectrograms. Can the number of bands, the frequency range over which the bands are observed, and their time variation be explained with Linear Mode Conversion Theory (LMCT) using realistic plasmapause models and Extreme Ultraviolet (EUV) plasmaspheric observations? In this paper we compare KC observations with simulated frequency emission bands based on LMCT for a number of cases. In LMCT the allowed frequency range across the equatorial plasmapause is restricted to frequencies much greater than the electron cyclotron frequency (fce) and less than the maximum plasma frequency in this region. Fce also determines the number of allowed bands in this range. Is the observed frequency range and number of bands consistent with the predications of LMCT? Can irregularities in the shape of plasmaspheric structures like notches be observed in the time variations of KC emissions? We will investigate these and other questions. Simulated radiation patterns will be generated by ray tracing calculations in the L-O mode from the radio window at the near equatorial plasmapause. The KC observations used in this study are from the Plasma Wave Instrument on the Geotail spacecraft and from the Radio Plasma Imager on the IMAGE spacecraft. The plasmasphere and plasmapause will be derived either from plasmasphere simulations, from images by the EUV imager on the IMAGE spacecraft, and by using empirical models. In situ plasma density measurements from a number of spacecraft will also be used in order to reconstruct the plasmasphere for these case studies.

  3. Anticrossing double Fano resonances generated in metallic/dielectric hybrid nanostructures using nonradiative anapole modes for enhanced nonlinear optical effects.

    PubMed

    Zhai, Wu-Chao; Qiao, Tie-Zhu; Cai, Dong-Jin; Wang, Wen-Jie; Chen, Jing-Dong; Chen, Zhi-Hui; Liu, Shao-Ding

    2016-11-28

    Third-harmonic generation with metallic or dielectric nanoparticles often suffer from, respectively, small modal volumes and weak near-field enhancements. This study propose and demonstrate that a metallic/dielectric hybrid nanostructure composed of a silver double rectangular nanoring and a silicon square nanoplate can be used to overcome these obstacles for enhanced third-harmonic generation. It is shown that the nonradiative anapole mode of the Si plate can be used as a localized source to excite the dark subradiant octupole mode of the Ag ring, and the mode hybridization leads to the formation of an antibonding and a bonding subradiant collective mode, thereby forming anticrossing double Fano resonances. With the strong coupling between individual particles and the effectively suppressed radiative losses of the Fano resonances, several strong hot spots are generated around the Ag ring due to the excitation of the octupole mode, and electromagnetic fields within the Si plate are also strongly amplified, making it possible to confine more incident energy inside the dielectric nanoparticle. Calculation results reveal that the confined energy inside the Si plate and the Ag ring for the hybrid structures can be about, respectively, more than three times and four orders stronger than that of the corresponding isolated nanoparticles, which makes the designed hybrid nanostructure a promising platform for enhanced third-harmonic generation.

  4. Ion beam generated modes in the lower hybrid frequency range in a laboratory magnetoplasma

    NASA Astrophysics Data System (ADS)

    Van Compernolle, B.; Tripathi, S.; Gekelman, W. N.; Colestock, P. L.; Pribyl, P.

    2012-12-01

    The generation of waves by ion ring distributions is of great importance in many instances in space plasmas. They occur naturally in the magnetosphere through the interaction with substorms, or they can be man-made in ionospheric experiments by photo-ionization of neutral atoms injected perpendicular to the earth's magnetic field. The interaction of a fast ion beam with a low β plasma has been studied in the laboratory. Experiments were performed at the LArge Plasma Device (LAPD) at UCLA. The experiments were done in a Helium plasma (n ≃ 1012 \\ cm-3, B0 = 1000 G - 1800 G, fpe}/f{ce ≃ 1 - 5, Te = 0.25\\ eV, vte ≤ vA). The ion beam \\cite{Tripathi_ionbeam} is a Helium beam with energies ranging from 5 keV to 18 keV. The fast ion velocity is on the order of the Alfvén velocity. The beam is injected from the end of the machine, and spirals down the linear device. Waves were observed below fci in the shear Alfvén wave regime, and in a broad spectrum above fci in the lower hybrid frequency range, the focus of this paper. The wave spectra have distinct peaks close to ion cyclotron harmonics, extending out to the 100th harmonic in some cases. The wave generation was studied for various magnetic fields and background plasma densities, as well as for different beam energies and pitch angles. The waves were measured with 3-axis electric and magnetic probes. Detailed measurements of the perpendicular mode structure will be shown. Langmuir probes were used to measure density and temperature evolution due to the beam-plasma interaction. Retarding field energy analyzers captured the ion beam profiles. The work was performed at the LArge Plasma Device at the Basic Plasma Science Facility (BaPSF) at UCLA, funded by DOE/NSF.

  5. Optimally coherent Kerr combs generated with crystalline whispering gallery mode resonators for ultrahigh capacity fiber communications.

    PubMed

    Pfeifle, Joerg; Coillet, Aurélien; Henriet, Rémi; Saleh, Khaldoun; Schindler, Philipp; Weimann, Claudius; Freude, Wolfgang; Balakireva, Irina V; Larger, Laurent; Koos, Christian; Chembo, Yanne K

    2015-03-06

    Optical Kerr frequency combs are known to be effective coherent multiwavelength sources for ultrahigh capacity fiber communications. These combs are the frequency-domain counterparts of a wide variety of spatiotemporal dissipative structures, such as cavity solitons, chaos, or Turing patterns (rolls). In this Letter, we demonstrate that Turing patterns, which correspond to the so-called primary combs in the spectral domain, are optimally coherent in the sense that for the same pump power they provide the most robust carriers for coherent data transmission in fiber communications using advanced modulation formats. Our model is based on a stochastic Lugiato-Lefever equation which accounts for laser pump frequency jitter and amplified spontaneous emission noise induced by the erbium-doped fiber amplifier. Using crystalline whispering-gallery-mode resonators with quality factor Q∼10^{9} for the comb generation, we show that when the noise is accounted for, the coherence of a primary comb is significantly higher than the coherence of their solitonic or chaotic counterparts for the same pump power. In order to confirm this theoretical finding, we perform an optical fiber transmission experiment using advanced modulation formats, and we show that the coherence of the primary comb is high enough to enable data transmission of up to 144  Gbit/s per comb line, the highest value achieved with a Kerr comb so far. This performance evidences that compact crystalline photonic systems have the potential to play a key role in a new generation of coherent fiber communication networks, alongside fully integrated systems.

  6. A theoretical analysis of the coordination modes of CuII with penicillins: activation of the beta-lactam C-N bond.

    PubMed

    Campomanes, Pablo; Menéndez, M Isabel; López, Ramón; Sordo, Tomás L

    2005-02-01

    The interaction of CuII with 6-formylamino-3alpha-carboxypenam and 6-acetylamino-3alpha-carboxypenam was investigated by means of DFT calculations with the UB3LYP functional. Nine different modes of complexation between CuII and 6-formylamino-3alpha-carboxypenam were located. When two water molecules directly bonded to CuII are included in the calculations on 6-acetylamino-3alpha-carboxypenam as penicillin model, only six CuII(H2O)2-6-acetylamino-3alpha-carboxypenam complexes (1S-6S) are found. In solution the four most stable complexes obtained from our calculations, 6S, 1S, 2S, and 3S, exhibit CuII in square-planar coordination with at least one bond to the carboxylate group, in agreement with experimental evidence. Complexes 6S, 1S, and 3S were previously suggested by available experimental evidence. In three of the most stable complexes (6S, 2S, and 3S) the beta-lactam C-N bond is remarkably activated and displays C-N bond lengths similar to those found in some tetrahedral intermediates located for the hydrolysis of 2-azetidinones. This suggests that these kinds of complexes belong to the reaction coordinate for the degradation of beta-lactam antibiotics in the presence of CuII.

  7. Ion beam generated modes in the lower hybrid frequency range in a laboratory magnetoplasma

    NASA Astrophysics Data System (ADS)

    van Compernolle, Bart; Tripathi, Shreekrishna Kp; Gekelman, Walter; Pribyl, Patrick; Colestock, Patrick

    2012-10-01

    The interaction of a fast ion beam with a low β plasma has been studied in the laboratory. Experiments were performed at the LArge Plasma Device (LAPD) at UCLA. The experiments were done in a Helium plasma (n ˜10^12 cm-3, B0 = 1000 G - 1800 G, fpe/fce˜1 - 5, Te= 0.25 eV, vtevA). The ion beam is a Helium beam with energies ranging from 5 keV to 18 keV. The fast ion velocity is on the order of the Alfv'en velocity. The beam is injected from the end of the machine, and spirals down the linear device. Waves were observed below fci in the shear Alfv'en wave regime, and in a broad spectrum above fci in the lower hybrid frequency range, the focus of this paper. The wave spectra have distinct peaks close to ion cyclotron harmonics, extending out to the 100th harmonic in some cases. The wave generation was studied for various plasma parameters, as well as for different beam energies and pitch angles. The waves were measured with 3-axis electric and magnetic probes. Detailed measurements of the perpendicular mode structure will be shown. Langmuir probes were used to measure density and temperature evolution due to the beam-plasma interaction. Retarding field energy analyzers captured the ion beam profiles.

  8. Fully integrated reflection-mode photoacoustic, two-photon, and second harmonic generation microscopy in vivo

    PubMed Central

    Song, Wei; Xu, Qiang; Zhang, Yang; Zhan, Yang; Zheng, Wei; Song, Liang

    2016-01-01

    The ability to obtain comprehensive structural and functional information from intact biological tissue in vivo is highly desirable for many important biomedical applications, including cancer and brain studies. Here, we developed a fully integrated multimodal microscopy that can provide photoacoustic (optical absorption), two-photon (fluorescence), and second harmonic generation (SHG) information from tissue in vivo, with intrinsically co-registered images. Moreover, using a delicately designed optical-acoustic coupling configuration, a high-frequency miniature ultrasonic transducer was integrated into a water-immersion optical objective, thus allowing all three imaging modalities to provide a high lateral resolution of ~290 nm with reflection-mode imaging capability, which is essential for studying intricate anatomy, such as that of the brain. Taking advantage of the complementary and comprehensive contrasts of the system, we demonstrated high-resolution imaging of various tissues in living mice, including microvasculature (by photoacoustics), epidermis cells, cortical neurons (by two-photon fluorescence), and extracellular collagen fibers (by SHG). The intrinsic image co-registration of the three modalities conveniently provided improved visualization and understanding of the tissue microarchitecture. The reported results suggest that, by revealing complementary tissue microstructures in vivo, this multimodal microscopy can potentially facilitate a broad range of biomedical studies, such as imaging of the tumor microenvironment and neurovascular coupling. PMID:27576922

  9. Fully integrated reflection-mode photoacoustic, two-photon, and second harmonic generation microscopy in vivo

    NASA Astrophysics Data System (ADS)

    Song, Wei; Xu, Qiang; Zhang, Yang; Zhan, Yang; Zheng, Wei; Song, Liang

    2016-08-01

    The ability to obtain comprehensive structural and functional information from intact biological tissue in vivo is highly desirable for many important biomedical applications, including cancer and brain studies. Here, we developed a fully integrated multimodal microscopy that can provide photoacoustic (optical absorption), two-photon (fluorescence), and second harmonic generation (SHG) information from tissue in vivo, with intrinsically co-registered images. Moreover, using a delicately designed optical-acoustic coupling configuration, a high-frequency miniature ultrasonic transducer was integrated into a water-immersion optical objective, thus allowing all three imaging modalities to provide a high lateral resolution of ~290 nm with reflection-mode imaging capability, which is essential for studying intricate anatomy, such as that of the brain. Taking advantage of the complementary and comprehensive contrasts of the system, we demonstrated high-resolution imaging of various tissues in living mice, including microvasculature (by photoacoustics), epidermis cells, cortical neurons (by two-photon fluorescence), and extracellular collagen fibers (by SHG). The intrinsic image co-registration of the three modalities conveniently provided improved visualization and understanding of the tissue microarchitecture. The reported results suggest that, by revealing complementary tissue microstructures in vivo, this multimodal microscopy can potentially facilitate a broad range of biomedical studies, such as imaging of the tumor microenvironment and neurovascular coupling.

  10. On dynamically generating relevant elementary flux modes in a metabolic network using optimization.

    PubMed

    Oddsdóttir, Hildur Æsa; Hagrot, Erika; Chotteau, Véronique; Forsgren, Anders

    2015-10-01

    Elementary flux modes (EFMs) are pathways through a metabolic reaction network that connect external substrates to products. Using EFMs, a metabolic network can be transformed into its macroscopic counterpart, in which the internal metabolites have been eliminated and only external metabolites remain. In EFMs-based metabolic flux analysis (MFA) experimentally determined external fluxes are used to estimate the flux of each EFM. It is in general prohibitive to enumerate all EFMs for complex networks, since the number of EFMs increases rapidly with network complexity. In this work we present an optimization-based method that dynamically generates a subset of EFMs and solves the EFMs-based MFA problem simultaneously. The obtained subset contains EFMs that contribute to the optimal solution of the EFMs-based MFA problem. The usefulness of our method was examined in a case-study using data from a Chinese hamster ovary cell culture and two networks of varied complexity. It was demonstrated that the EFMs-based MFA problem could be solved at a low computational cost, even for the more complex network. Additionally, only a fraction of the total number of EFMs was needed to compute the optimal solution.

  11. A phosphomide based PNP ligand, 2,6-{Ph2PC(O)}2(C5H3N), showing PP, PNP and PNO coordination modes.

    PubMed

    Kumar, Pawan; Kashid, Vitthalrao S; Reddi, Yernaidu; Mague, Joel T; Sunoj, Raghavan B; Balakrishna, Maravanji S

    2015-03-07

    A new class of PNP pincer ligands, pyridine-2,6-diylbis(diphenylphosphino)methanone, 2,6-{Ph2PC(O)}2(C5H3N) (1) (hereafter referred to as "bis(phosphomide)"), was prepared by the reaction of picolinoyldichloride with diphenylphosphine in the presence of triethylamine. The bis(phosphomide) 1 shows symmetrical PNP, unsymmetrical PNO and simple bidentate PP coordination modes when treated with various transition metal precursors. The reaction between 1 and [Ru(p-cymene)Cl2]2 in a 1 : 1 molar ratio yielded a binuclear complex [Ru2Cl4(NCCH3)(p-cymene){2,6-{Ph2PC(O)}2(C5H3N)}] (2) containing an unsymmetrical PNO pincer cage around one of the ruthenium centers, whereas the second ruthenium is bonded to the other phosphorus atom along with cymene and two chloride atoms. Symmetrical pincer complexes [RuCl(NCCH3)2{2,6-{Ph2PC(O)}2(C5H3N)}](ClO4) (3), [Ru(η(5)-C5H5){2,6-{Ph2PC(O)}2(C5H3N)}](OTf) (4) and [RhCl{2,6-{Ph2PC(O)}2(C5H3N)}] (5) were obtained in the respective reactions of 1 with [RuCl(NCCH3)2(p-cymene)](ClO4), [Ru(η(5)-C5H5)Cl(PPh3)2] and [Rh(COD)Cl]2. Group 10 metal complexes [NiCl{2,6-{Ph2PC(O)}2(C5H3N)}](BF4) (6), [PdCl{2,6-{Ph2PC(O)}2(C5H3N)}]ClO4 (7) and [PtCl{2,6-{Ph2PC(O)}2(C5H3N)}]ClO4 (8) were obtained by transmetallation reactions of in situ generated Ag(I) salts of 1 with Ni(DME)Cl2 or M(COD)Cl2 (M = Ni, Pd and Pt). The reactions between 1 and CuX or [Cu(NCCH3)4](BF4) produced mononuclear complexes of the type [CuX{2,6-{Ph2PC(O)}2(C5H3N)}] (9, X = Cl; 10, X = Br; 11, X = I), [Cu(NCCH3){Ph2C(O)}2(C5H3N)}](BF4) (12) and [Cu{Ph2C(O)}2(C5H3N)}2](BF4) (13). Similarly, the silver complexes [AgX{2,6-{Ph2PC(O)}2(C5H3N)}] (14, X = ClO4; 15, X = Br) were obtained by the treatment of 1 with AgClO4 or AgBr in 1 : 1 molar ratios. Treatment of 1 with AuCl(SMe2) in 1 : 1 and 1 : 2 molar ratios produced mono- and binuclear complexes, [AuCl{2,6-{Ph2PC(O)}2(C5H3N)}] (16) and [Au2Cl2{2,6-{Ph2PC(O)}2(C5H3N)}] (17), in good yield. The structures of ligand 1

  12. Regionalization and intersegmental coordination of rhythm-generating networks in the spinal cord of the chick embryo.

    PubMed

    Ho, S; O'Donovan, M J

    1993-04-01

    We have examined the regionalization and coordination of rhythm-generating networks in the isolated spinal cord of the chick embryo between embryonic days 9 and 13, by recording the pattern of rhythmic activity recorded from muscle nerves and ventral roots following a variety of lesions. We found that the capacity for rhythmic activity is distributed along the rostrocaudal axis of the cord but can be expressed in a single, isolated segment. Specializations within the lumbosacral cord were investigated by isolating particular regions and recording their motor output. The rostral part of the lumbosacral cord generates more cycles than the caudal part, and this difference becomes more pronounced with development. In the unlesioned cord, motoneuron activity is synchronized along the rostrocaudal axis. Lesion experiments revealed that the synchronization of motoneuron activity and the synaptic drive to caudal motoneurons is mediated in part by propriospinal pathways traveling in the ventrolateral white matter tracts and by synaptic interactions within the gray matter. The dorsal fiber tracts may also be involved but their effects appear to be weak. Lesions in dorsal-ventral and mediolateral planes were used to localize regions critical for rhythmogenesis and for the alternation of flexor and extensor motoneurons. Rhythmic activity with alternation persisted in spinal cords in which the dorsal and medial half had been removed. Severe medial or dorsal lesions, resulting in a thin strip of lateral or ventral gray matter, altered the phasing of motoneuron activity from alternating to synchronous without effects on cycle timing. These results suggest that the critical neural components for alternation are located close to and dorsomedial to the lateral motor column, and that the capacity for rhythmogenesis is distributed widely throughout the ventral gray matter and is not localized to specific nuclei.

  13. Polydopamine-based coordination nanocomplex for T1/T2 dual mode magnetic resonance imaging-guided chemo-photothermal synergistic therapy.

    PubMed

    Chen, Yan; Ai, Kelong; Liu, Jianhua; Ren, Xiaoyan; Jiang, Chunhuan; Lu, Lehui

    2016-01-01

    Despite the progress in the design and synthesis of theranostic agents, limitations on efficiency and safety offer significant room for improvement in these agents. Inspired by the natural binding ability of polydopamine nanospheres (PDAs) with iron ion, a simple and versatile synthesis strategy is developed to prepare biodegradable coordination polymer (CP) encapsulated PDAs nanocomplex (PDAs@CPx, x = 3, 6, 9). We found that the PDAs@CP3 can serve as a T1/T2 dual mode contrast agent (DMCA) for magnetic resonance imaging (MRI), which possesses high longitudinal (r1 = 7.524 mM(-1) s(-1)) and transverse (r2 = 45.92 mM(-1) s(-1)) relaxivities. In this system, benefitting from the high photothermal conversion efficiency derived from PDAs, DOX loaded PDAs@CP3 nanocomplex is able to not only destroy the tumor directly by heat, but also stimulate the chemotherapy by enabling NIR-responsive on demand delivery of DOX. To the best of our knowledge, this is the first example exploring the potential of PDAs@CPx nanocomplex for T1/T2 dual mode MRI-guided chemo-photothermal synergistic therapy. This work extends the currently available theranostic agents, and opens up new avenues to rationally design the high-performance T1/T2 DMCA.

  14. Direct generation of 128-fs Gaussian pulses from a compensation-free fiber laser using dual mode-locking mechanisms

    NASA Astrophysics Data System (ADS)

    Peng, Junsong; Zhan, Li; Gu, Zhaochang; Qian, Kai; Luo, Shouyu; Shen, Qishun

    2012-03-01

    We have experimentally demonstrated the direct generation of 128-fs pulses in an all-anomalous-dispersion all-fiber mode-locked laser. The laser is free of dispersion compensation in the cavity based on standard single mode fiber (SMF). The time-bandwidth product is 0.536. The laser is achieved by using two mode-lockers, one is nonlinear polarization rotation (NPR), and the other is nonlinear amplifying loop mirror. The coexistence of dual mode-locking mechanisms can decrease the cavity length to 12-m, and also results in producing high-quality pulses with a Gaussian shape both on the pulse profile and spectrum, but without Kelly sidebands.

  15. Hybrid Alfven resonant mode generation in the magnetosphere-ionosphere coupling system

    SciTech Connect

    Hiraki, Yasutaka; Watanabe, Tomo-Hiko

    2012-10-15

    Feedback unstable Alfven waves involving global field-line oscillations and the ionospheric Alfven resonator (IAR) were comprehensively studied to clarify their properties of frequency dispersion, growth rate, and eigenfunctions. It is discovered that a new mode called here the hybrid Alfven resonant (HAR) mode can be destabilized in the magnetosphere-ionosphere coupling system with a realistic Alfven velocity profile. The HAR mode found in a high frequency range over 0.3 Hz is caused by coupling of IAR modes with strong dispersion and magnetospheric cavity resonances. The harmonic relation of HAR eigenfrequencies is characterized by a constant frequency shift from those of IAR modes. The three modes are robustly found even if effects of two-fluid process and ionospheric collision are taken into account and thus are anticipated to be detected by magnetic field observations in a frequency range of 0.3-1 Hz in auroral and polar-cap regions.

  16. Supramolecular solar cells: surface modification of nanocrytalline TiO(2) with coordinating ligands to immobilize sensitizers and dyads via metal-ligand coordination for enhanced photocurrent generation.

    PubMed

    Subbaiyan, Navaneetha K; Wijesinghe, Channa A; D'Souza, Francis

    2009-10-21

    An elegant method of self-assembly for modification of a TiO(2) surface using coordinating ligands followed by immobilization of variety of sensitizers and a dyad is reported. This highly versatile method, in addition to testing the photoelectrochemical behavior of different zinc tetrapyrroles, allowed the use of fairly complex structures involving more than one donor entity. Utilization of the zinc porphyrin-ferrocene dyad markedly improved the current-voltage performance of the photoelectrochemical cell through an electron transfer-hole migration mechanism. Incident photon-to-current efficiency values up to 37% were obtained for the electrode modified with the dyad, signifying the importance of photocells built on the basis of biomimetic principles for efficient harvesting of solar energy.

  17. Model of a single mode energy harvester and properties for optimal power generation

    NASA Astrophysics Data System (ADS)

    Liao, Yabin; Sodano, Henry A.

    2008-12-01

    The process of acquiring the energy surrounding a system and converting it into usable electrical energy is termed power harvesting. In the last few years, the field of power harvesting has experienced significant growth due to the ever increasing desire to produce portable and wireless electronics with extended life. Current portable and wireless devices must be designed to include electrochemical batteries as the power source. The use of batteries can be troublesome due to their finite energy supply, which necessitates their periodic replacement. In the case of wireless sensors that are to be placed in remote locations, the sensor must be easily accessible or of disposable nature to allow the device to function over extended periods of time. Energy scavenging devices are designed to capture the ambient energy surrounding the electronics and covert it into usable electrical energy. The concept of power harvesting works towards developing self-powered devices that do not require replaceable power supplies. The development of energy harvesting systems is greatly facilitated by an accurate model to assist in the design of the system. This paper will describe a theoretical model of a piezoelectric based energy harvesting system that is simple to apply yet provides an accurate prediction of the power generated around a single mode of vibration. Furthermore, this model will allow optimization of system parameters to be studied such that maximal performance can be achieved. Using this model an expression for the optimal resistance and a parameter describing the energy harvesting efficiency will be presented and evaluated through numerical simulations. The second part of this paper will present an experimental validation of the model and optimal parameters.

  18. Generation of real-time mode high-resolution water vapor fields from GPS observations

    NASA Astrophysics Data System (ADS)

    Yu, Chen; Penna, Nigel T.; Li, Zhenhong

    2017-02-01

    Pointwise GPS measurements of tropospheric zenith total delay can be interpolated to provide high-resolution water vapor maps which may be used for correcting synthetic aperture radar images, for numeral weather prediction, and for correcting Network Real-time Kinematic GPS observations. Several previous studies have addressed the importance of the elevation dependency of water vapor, but it is often a challenge to separate elevation-dependent tropospheric delays from turbulent components. In this paper, we present an iterative tropospheric decomposition interpolation model that decouples the elevation and turbulent tropospheric delay components. For a 150 km × 150 km California study region, we estimate real-time mode zenith total delays at 41 GPS stations over 1 year by using the precise point positioning technique and demonstrate that the decoupled interpolation model generates improved high-resolution tropospheric delay maps compared with previous tropospheric turbulence- and elevation-dependent models. Cross validation of the GPS zenith total delays yields an RMS error of 4.6 mm with the decoupled interpolation model, compared with 8.4 mm with the previous model. On converting the GPS zenith wet delays to precipitable water vapor and interpolating to 1 km grid cells across the region, validations with the Moderate Resolution Imaging Spectroradiometer near-IR water vapor product show 1.7 mm RMS differences by using the decoupled model, compared with 2.0 mm for the previous interpolation model. Such results are obtained without differencing the tropospheric delays or water vapor estimates in time or space, while the errors are similar over flat and mountainous terrains, as well as for both inland and coastal areas.

  19. Interplay of nonclassicality and entanglement of two-mode Gaussian fields generated in optical parametric processes

    NASA Astrophysics Data System (ADS)

    Arkhipov, Ievgen I.; Peřina, Jan; Peřina, Jan; Miranowicz, Adam

    2016-07-01

    The behavior of general nonclassical two-mode Gaussian states at a beam splitter is investigated. Single-mode nonclassicality as well as two-mode entanglement of both input and output states are analyzed suggesting their suitable quantifiers. These quantifiers are derived from local and global invariants of linear unitary two-mode transformations such that the sum of input (or output) local nonclassicality measures and entanglement measure gives a global invariant. This invariant quantifies the global nonclassicality resource. Mutual transformations of local nonclassicalities and entanglement induced by the beam splitter are analyzed considering incident noisy twin beams, single-mode noisy squeezed vacuum states, and states encompassing both squeezed states and twin beams. A rich tapestry of interesting nonclassical output states is predicted.

  20. Generation of 0. 7--0. 8. mu. picosecond pulses in an alexandrite laser with passive mode locking

    SciTech Connect

    Lisitsyn, V.N.; Matrosov, V.N.; Orekhova, V.P.; Pestryakov, E.V.; Sevast'yanov, B.K.; Trunov, V.I.; Zenin, V.N.; Remigailo, Y.L.

    1982-03-01

    Picosecond pulses of 0.7--0.8 ..mu.. wavelengths were generated in an alexandrite laser as a result of electronic--vibrational transitions /sup 4/T/sub 2/ ..-->.. /sup 4/A/sub 2/+h..omega../sub phonon/. Passive mode locking was ensured by the use of DS1 and DTTS saturable absorbers. The duration of the pulses generated using DS1 was 8 psec at wavelengths of 0.725--0.745 ..mu.., whereas the duration of the pulses generated using DTTS was 90 psec in the range 0.75--0.775 ..mu...

  1. Analysis of the stability of an active mode-locking pulsed laser for ultra-short pulses generation

    NASA Astrophysics Data System (ADS)

    Bracamontes Rodríguez, Y. E.; Beltrán Pérez, G.; Kuzin, Eugin; Castillo Mixcóatl, J.; Muñoz Aguirre, S.

    2013-11-01

    Pulsed lasers have become very important owing to the great amount of applications, from communications to diverse medicine areas. Many works have reported the development of these kinds of sources which uses quite complex cavity configurations and that present instabilities in the output signal. In this work the analysis of a pulsed laser that uses a ring cavity with a length of 16.5 m is presented. A phase modulator (LiNbO3) controlled by an RF generator operated at a frequency of 12.5108 MHz was used to perform the mode lock. The modulator input has a birrefringent fiber then the light polarization affects the mode lock. Therefore it was necessary to perform an analysis and characterization in the input and output signals of the modulator in order to obtain more stable output pulses without requiring a continuous adjustment. The laser implemented with 2 modes of operation, active mode-lock and passive mode-lock. The obtained pulses whit temporal width of 7 ns FWHM for the frequency fundamental 12.5108 MHz and 781 -261-120-116 ps for the harmonic 5-10-16-20 .The results for the passive mode-lock the obtained pulses whit temporal width 2 ps and average power 200 W.

  2. Generation of high-order Hermite-Gaussian modes in end-pumped solid-state lasers for square vortex array laser beam generation.

    PubMed

    Chu, Shu-Chun; Chen, Yun-Ting; Tsai, Ko-Fan; Otsuka, Kenju

    2012-03-26

    This study reports the first systematic approach to the excitation of all high-order Hermite-Gaussian modes (HGMs) in end-pumped solid-state lasers. This study uses a metal-wire-inserted laser resonator accompanied with the "off axis pumping" approach. This study presents numerical analysis of the excitation of HGMs in end-pumped solid-state lasers and experimentally generated HGM patterns. This study also experimentally demonstrates the generation of an square vortex array laser beams by passing specific high-order HGMs (HGn,n + 1 or HGn + 1,n modes) through a Dove prism-embedded unbalanced Mach-Zehnder interferometer [Optics Express 16, 19934-19949]. The resulting square vortex array laser beams with embedded vortexes aligned in a square array can be applied to multi-spot dark optical traps in the future.

  3. Theory of plasmonic femtosecond pulse generation by mode-locking of long-range surface plasmon polariton lasers.

    PubMed

    Kim, Kwang-Hyon; Husakou, Anton; Herrmann, Joachim

    2012-01-02

    We develop a semiclassical theory of passively mode-locked surface plasmon polariton (SPP) lasers based on a SPP Bragg resonator with a metal film deposited on a polymer host and adjacent layers of a slow saturable absorber and a slow saturable gain medium. The mode-locked laser dynamics is studied for the case that both the gain medium and the saturable absorber are solid-state dyes. The SPP laser pulse parameters are calculated in dependence on layer thicknesses of the metal film and pump parameters. We predict the possibility of SPP pulse generation with ∼ 100 fs pulse duration.

  4. Mode-hopping mechanism generating colored noise in a magnetic tunnel junction based spin torque oscillator

    SciTech Connect

    Sharma, Raghav; Dürrenfeld, P.; Iacocca, E.; Heinonen, O. G.; Åkerman, J.; Muduli, P. K.

    2014-09-29

    The frequency noise spectrum of a magnetic tunnel junction based spin torque oscillator is examined where multiple modes and mode-hopping events are observed. The frequency noise spectrum is found to consist of both white noise and 1/f frequency noise. We find a systematic and similar dependence of both white noise and 1/f frequency noise on bias current and the relative angle between the reference and free layers, which changes the effective damping and hence the mode-hopping behavior in this system. The frequency at which the 1/f frequency noise changes to white noise increases as the free layer is aligned away from the anti-parallel orientation w.r.t the reference layer. These results indicate that the origin of 1/f frequency noise is related to mode-hopping, which produces both white noise as well as 1/f frequency noise similar to the case of ring lasers.

  5. Two-mode correlation of microwave quantum noise generated by parametric down-conversion.

    PubMed

    Bergeal, N; Schackert, F; Frunzio, L; Devoret, M H

    2012-03-23

    In this Letter, we report the observation of the correlation between two modes of microwave radiation resulting from the amplification of quantum noise by the Josephson parametric converter. This process, seen from the pump, can be viewed as parametric down-conversion. The correlation is measured by an interference experiment displaying a contrast better than 99% with a number of photons per mode greater than 250,000. Dispersive measurements of mesoscopic systems and quantum encryption can benefit from this development.

  6. Coordination-directed one-dimensional coordination polymers generated from a new oxadiazole bridging ligand and HgX2 (X=Cl, Br and I).

    PubMed

    Yang, Rui; Ma, Jian Ping; Huang, Ru Qi; Dong, Yu Bin

    2011-06-01

    A new 1,3,4-oxadiazole bridging bent organic ligand, 2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole, C(28)H(24)N(4)O(3), L, has been used to create three novel one-dimensional isomorphic coordination polymers, viz. catena-poly[[[dichloridomercury(II)]-μ-2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole] methanol monosolvate], {[HgCl(2)(C(28)H(24)N(4)O(3))]·CH(3)OH}(n), catena-poly[[[dibromidomercury(II)]-μ-2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole] methanol monosolvate], {[HgBr(2)(C(28)H(24)N(4)O(3))]·CH(3)OH}(n), and catena-poly[[[diiodidomercury(II)]-μ-2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole] methanol monosolvate], {[HgI(2)(C(28)H(24)N(4)O(3))]·CH(3)OH}(n). The free L ligand itself adopts a cis conformation, with the two terminal pyridine rings and the central oxadiazole ring almost coplanar [dihedral angles = 5.994 (7) and 9.560 (6)°]. In the Hg(II) complexes, however, one of the flexible pyridylmethyl arms of ligand L is markedly bent and helical chains are obtained. The Hg(II) atom lies in a distorted tetrahedral geometry defined by two pyridine N-atom donors from two L ligands and two halide ligands. The helical chains stack together via interchain π-π interactions that expand the dimensionality of the structure from one to two. The methanol solvent molecules link to the complex polymers through O-H···N and O-H···O hydrogen bonds.

  7. Generation of sub-100 fs pulses from mode-locked Nd,Y:SrF2 laser with enhancing SPM

    NASA Astrophysics Data System (ADS)

    Zhu, Jiangfeng; Wei, Long; Tian, Wenlong; Liu, Jiaxing; Wang, Zhaohua; Su, Liangbi; Xu, Jun; Wei, Zhiyi

    2016-05-01

    A mode-locked laser using Nd,Y:SrF2 crystal as the gain medium is presented in this letter. By special design of the cavity for enhancing the self-phase modulation effect, femtosecond mode-locking with 97 fs pulse duration and 13.2 nm spectral width centered at 1061 nm is obtained at a repetition rate of 96 MHz. The average output power is 102 mW under 925 mW pump power, corresponding to the optical-to-optical efficiency of 11%. To the best of our knowledge, these are the first sub-100 fs pulses generated from a mode-locked Nd doped crystal laser.

  8. On the Interactive-beating-modes Model: Generation of Asymmetric Multiplet Structures and Explanation of the Blazhko Effect

    NASA Astrophysics Data System (ADS)

    Bryant, Paul H.

    2016-02-01

    This paper considers a nonlinear coupling between a radial and a nonradial mode of nearly the same frequency. The results may be of general interest, but in particular have application to the “beating-modes model” of the Blazhko effect which was recently shown to accurately reproduce the light curve of RR Lyr. For weak coupling, the two modes do not phase-lock and they retain separate frequencies, but the coupling nevertheless has important consequences. Upon increasing the coupling strength from zero, an additional side-peak emerges in the spectrum forming an asymmetric triplet centered on the fundamental. As the coupling is further increased, the amplitude of this side-peak increases and the three peaks are also pulled toward each other, decreasing the Blazhko frequency. Beyond a critical coupling strength, phase-locking occurs between the modes. With appropriate choice of coupling strength, this “interactive beating-modes model” can match the side-peak amplitude ratio of any star. The effects of nonlinear damping are also explored and found to generate additional side-peaks of odd order. Consistent with this, the odd side-peaks are found to be favored in V808 Cyg. It is also shown that the Blazhko effect generates a fluctuating “environment” that can have a modulatory effect on other excited modes of the star. An example is found in V808 Cyg where the modulation is at double the Blazhko frequency. An explanation is found for this mysterious doubling, providing additional evidence in favor of the model.

  9. A Coordinate-Based Meta-Analysis of Overlaps in Regional Specialization and Functional Connectivity across Subjective Value and Default Mode Networks

    PubMed Central

    Acikalin, M. Yavuz; Gorgolewski, Krzysztof J.; Poldrack, Russell A.

    2017-01-01

    Previous research has provided qualitative evidence for overlap in a number of brain regions across the subjective value network (SVN) and the default mode network (DMN). In order to quantitatively assess this overlap, we conducted a series of coordinate-based meta-analyses (CBMA) of results from 466 functional magnetic resonance imaging experiments on task-negative or subjective value-related activations in the human brain. In these analyses, we first identified significant overlaps and dissociations across activation foci related to SVN and DMN. Second, we investigated whether these overlapping subregions also showed similar patterns of functional connectivity, suggesting a shared functional subnetwork. We find considerable overlap between SVN and DMN in subregions of central ventromedial prefrontal cortex (cVMPFC) and dorsal posterior cingulate cortex (dPCC). Further, our findings show that similar patterns of bidirectional functional connectivity between cVMPFC and dPCC are present in both networks. We discuss ways in which our understanding of how subjective value (SV) is computed and represented in the brain can be synthesized with what we know about the DMN, mind-wandering, and self-referential processing in light of our findings. PMID:28154520

  10. Complexation of Curium(III) with DTPA at 10–70 °C: Comparison with Eu(III)–DTPA in Thermodynamics, Luminescence, and Coordination Modes

    SciTech Connect

    Tian, Guoxin; Zhang, Zhiyong; Martin, Leigh R.; Rao, Linfeng

    2015-02-16

    Separation of trivalent actinides (An(III)) from trivalent lanthanides (Ln(III)) is a challenging task because of their nearly identical chemical properties. Diethylenetriaminepentaacetate (DTPA), a key reagent used in the TALSPEAK process that effectively separates An(III) from Ln(III), is believed to play a critical role in the An(III)/Ln(III) separation. However, the underlying principles for the separation based on the difference in the complexation of DTPA with An(III) and Ln(III) remain unclear. In this work, the complexation of DTPA with Cm(III) at 10-70 ºC was investigated by spectrophotometry, luminescence spectroscopy, and microcalorimetry, in conjunction with computational methods. The binding strength, the enthalpy of complexation, the coordination modes, and the luminescence properties are compared between the Cm(III)-DTPA and Eu(III)-DTPA systems. The experimental and computational data have demonstrated that the difference between Cm(III) and Eu(III) in the binding strength with DTPA can be attributed to the stronger covalence bonding between Cm(III) and the nitrogen donors of DTPA.

  11. Synthesis, crystal structures and coordination modes of some triorganotin(IV) complexes with 2-N-propyl and 2-N-benzyl-amino-1-cyclopentene-1-dithiocarboxylates

    NASA Astrophysics Data System (ADS)

    López-Cardoso, Marcela; Vargas-Pineda, Gabriela; Román-Bravo, Perla Patricia; Rodríguez-Narváez, Cristina; Rosas-Valdez, Elena; Cea-Olivares, Raymundo

    2016-07-01

    The syntheses and characterization of six new triorganotin(IV) complexes, Ph3Sn(PrACDA) (1), Bu3Sn(PrACDA) (2), Ph3Sn(BzACDA) (3), Bu3Sn(BzACDA) (4), Me3Sn(BzACDA) (5) and Cy3Sn(BzACDA) (6) (ACDA = 2-amino-1-cyclopentene-1-carbodithioate anion) are reported. Compounds 1-6 were synthesized by the reaction between the sodium salts of 2-N-propyl- or 2-N-benzyl-2-amino-1-cyclopentene-1-carbodithioate and R3SnCl (R = Ph, Bu, Me, Cy) in a 1:1 M ratio. The complexes were characterized by elemental analyses, IR and NMR (1H, 13C and 119Sn) spectroscopy and by FAB+ mass spectrometry. The experimental data reveal that the tin atom is coordinated to the ligand by means of the two sulfur atoms from the carbodithioate group in an anisobidentate mode, while the 119Sn{1H} NMR spectra suggest a pentacoordinate metal center in 1-4 and a tetracoordinate tin atom for 5 and 6. The molecular structures of complexes 1, 3 and 5 were confirmed by single crystal X-ray diffraction analysis showing the presence of N-H···S hydrogen bonding and a distorted trigonal bipyramid geometry for the tin atoms.

  12. Effect of Self-generated Radial Electric Field on Internal Collapse induced by m=1 Kinetic Kink Mode

    NASA Astrophysics Data System (ADS)

    Matsumoto, Taro; Tokuda, Shinji; Kishimoto, Yasuaki; Takizuka, Tomonori; Naitou, Hiroshi

    1998-11-01

    Effect of Self-generated Radial Electric Field on Internal Collapse induced by m=1 Kinetic Kink Mode Matsumoto Taro, Tokuda Shinji, Kishimoto Yasuaki, Takizuka Tomonori Naka Fusion Research Establishment, Japan Atomic Energy Research Institute, Japan and Naitou Hiroshi Department of Electrical and Electronic Engineering, Yamaguchi University, Japan The density gradient effect is taken into account in the gyro-kinetic nonlinear simulation of the kinetic m=1 internal kink mode in a cylindrical plasma. Even when the density gradient is not so large enough to change the process of the full reconnection, the process of the post-reconnection phase is changed considerably due to the self-generated radial electric field, i.e. m/n = 0/0 mode induced by the nonlinear interaction. The radial electric field grows to the same level as the 1/1 mode, and drives a ExB plasma rotation in the ion diamagnetic direction. The density and current distribution, and therefore q-min value after the full reconnection, are found to be significantly affected by the rotation.

  13. Soliton generation from an actively mode-locked fiber laser incorporating an electro-optic fiber modulator.

    PubMed

    Malmström, Mikael; Margulis, Walter; Tarasenko, Oleksandr; Pasiskevicius, Valdas; Laurell, Fredrik

    2012-01-30

    This work demonstrates an actively mode-locked fiber laser operating in soliton regime and employing an all-fiber electro-optic modulator. Nonlinear polarization rotation is utilized for femtosecond pulse generation. Stable operation of the all-fiber ring laser is readily achieved at a fundamental repetition rate of 2.6 MHz and produces 460 fs pulses with a spectral bandwidth of 5.3 nm.

  14. On the generation of octave-spanning optical frequency combs using monolithic whispering-gallery-mode microresonators.

    PubMed

    Chembo, Yanne K; Yu, Nan

    2010-08-15

    Octave-spanning optical frequency combs are especially interesting in optical metrology owing to the ability of self-referencing. We report a theoretical study on the generation of octave-spanning combs in the whispering gallery modes of a microresonator. Through a modal expansion model simulation in a calcium fluoride microcavity, we show that a combination of suitable pump power, Kerr nonlinearity, and dispersion profile can lead to stable and robust octave-spanning optical frequency combs.

  15. Q-switched-like soliton bunches and noise-like pulses generation in a partially mode-locked fiber laser.

    PubMed

    Wang, Zhenhong; Wang, Zhi; Liu, Yan-Ge; Zhao, Wenjing; Zhang, Hao; Wang, Shangcheng; Yang, Guang; He, Ruijing

    2016-06-27

    We report an intermediate regime between c.w. emission and noise-like pulses (NLPs) regime in an Er-doped partially mode-locked fiber laser with nonlinear polarization rotation. In this regime, the soliton bunches stochastically turn up from a quasi-cw background in the Q-switched-like envelope. The soliton bunches normally last for tens or hundreds of intracavity round-trips. When the soliton bunches vanish, typical NLPs chains are generated sporadically at location where the soliton bunches collapses. These results would be helpful to understand the generation and property of the NLPs regime.

  16. Generation of double-scale femto/pico-second optical lumps in mode-locked fiber lasers.

    PubMed

    Kobtsev, Sergey; Kukarin, Sergey; Smirnov, Sergey; Turitsyn, Sergey; Latkin, Anton

    2009-11-09

    We observed generation of stable picoseconds pulse train and double-scale optical lumps with picosecond envelope and femtosecond noise-like oscillations in the same Yb-doped fiber laser with all-positive-dispersion cavity mode-locked due to the effect of non-linear polarization evolution. In the noise-like pulse generation regime the auto-correlation function has a non-usual double (femto- and picosecond) scale shape. We discuss mechanisms of laser switching between two operation regimes and demonstrate a good qualitative agreement between experimental results and numerical modeling based on modified nonlinear Schrödinger equations.

  17. Simultaneous low noise radio frequency tone and narrow linewidth optical comb generation from a regeneratively mode-locked laser

    NASA Astrophysics Data System (ADS)

    Ozdur, Ibrahim; Ozharar, Sarper; Delfyett, Peter J.

    2014-10-01

    A regeneratively mode-locked laser with simultaneous low noise radio frequency (RF) tone and optical comb generation is presented. The laser does not need any external RF signal and emits a pulse train at ˜10 GHz repetition rate with a 1.5-ps optical pulse width after compression. The generated RF tone has a signal-to-noise ratio of 121 dB/Hz and an RF fluctuation of 10-9 over 0.1 s. The optical frequency comb spacing is also at ˜10 GHz and the optical comb tooth has a linewidth of <1 kHz.

  18. New modes of becoming in transcultural glocal spaces: second-generation youth in Calgary, Winnipeg, and Toronto.

    PubMed

    Hébert, Yvonne; Wilkinson, Lori; Ali, Mehrunnisa Ahmad; Oriola, Temitope

    2008-01-01

    Second generation youth are currently the focus of much research and policy attention with respect to their integration, which is not yet well understood. Based on graphic and narrative data recently collected in three cities, Calgary, Winnipeg, and Toronto, we analyse second generation youth's patterns in glocal spaces where transcultural modes of belonging are created and lived. Our analysis focuses on attachments to locality and a continuum of mobilities of mind, body, and boundaries. The findings are interpreted in terms of the complexities of their integration processes as well as their relevance to social policy development.

  19. Analysis Coordinator Report

    NASA Technical Reports Server (NTRS)

    Nothnagel, A.

    2013-01-01

    We present the IVS analysis coordination issues of 2012. The IVS Analysis Coordinator is responsible for generating and disseminating the official IVS products. This requires consistency of the input data by strict adherence to models and conventions. The term of the current IVS Analysis Coordinator will end on February 28, 2013.

  20. Picosecond pulse generation from a synchronously pumped mode-locked semiconductor laser diode

    NASA Technical Reports Server (NTRS)

    Auyeung, J. C.; Johnston, A. R.

    1982-01-01

    A semiconductor laser diode was mode locked in an external cavity when synchronously pumped with 90-ps current pulses. Transform-limited optical pulses with a 10-ps pulse width and a peak power of 160 mW were produced. Operating characteristics of such a system are described.

  1. Drive Train Normal Modes Analysis for the ERDA/NASA 100-Kilowatt Wind Turbine Generator

    NASA Technical Reports Server (NTRS)

    Sullivan, T. L.; Miller, D. R.; Spera, D. A.

    1977-01-01

    Natural frequencies, as a function of power were determined using a finite element model. Operating conditions investigated were operation with a resistive electrical load and operation synchronized to an electrical utility grid. The influence of certain drive train components on frequencies and mode shapes is shown. An approximate method for obtaining drive train natural frequencies is presented.

  2. Towards next-generation label-free biosensors: recent advances in whispering gallery mode sensors.

    PubMed

    Kim, Eugene; Baaske, Martin D; Vollmer, Frank

    2017-03-29

    Whispering gallery mode biosensors have been widely exploited over the past decade to study molecular interactions by virtue of their high sensitivity and applicability in real-time kinetic analysis without the requirement to label. There have been immense research efforts made for advancing the instrumentation as well as the design of detection assays, with the common goal of progressing towards real-world sensing applications. We therefore review a set of recent developments made in this field and discuss the requirements that whispering gallery mode label-free sensors need to fulfill for making a real world impact outside of the laboratory. These requirements are directly related to the challenges that these sensors face, and the methods proposed to overcome them are discussed. Moving forward, we provide the future prospects and the potential impact of this technology.

  3. Compensation of thermal lensing effect and TEM00-mode generation in cw Nd:YAG lasers

    NASA Astrophysics Data System (ADS)

    Jang, Won Kweon; Shin, Seong Sook; Lee, Sungman

    2003-11-01

    The thermally induced birefringence was successfully compensated by placing a quarter-wave plate into a plane parallel Nd:YAG laser resonator of 130 W output power in multi-mode. The optimal conversion efficiency was 38.3% and the slope efficiency was 58.2% with output coupler of 80% reflectance, and the beam quality factor of M2 was 26.7. For higher modes elimination, an aperture of 1.5 mm in diameter was inserted into resonator, and M2 was decreased to 1.8. However, the insertion of quarter-wave plate made an additional improvement to 1.15 of M2 value by alternating their radial and tangential polarization directions every bouncing feedback. We report the experimental results with theoretical analysis for high power solid-state laser fabrication with better beam quality.

  4. Mid-infrared mode-locked pulse generation with multilayer black phosphorus as saturable absorber.

    PubMed

    Qin, Zhipeng; Xie, Guoqiang; Zhao, Chujun; Wen, Shuangchun; Yuan, Peng; Qian, Liejia

    2016-01-01

    A mid-infrared saturable absorber mirror is successfully fabricated by transferring the mechanically exfoliated black phosphorus onto the gold-coated mirror. With the as-prepared black phosphorus saturable absorber mirror, a continuous-wave passively mode-locked Er:ZBLAN fiber laser is demonstrated at the wavelength of 2.8 μm, which delivers a maximum average output power of 613 mW, a repetition rate of 24 MHz, and a pulse duration of 42 ps. To the best of our knowledge, this is the first time a black phosphorus mode-locked laser at 2.8 μm wavelength has been demonstrated. Our results demonstrate the feasibility of black phosphorus flake as a new two-dimensional material for application in mid-infrared ultrafast photonics.

  5. Semiclassical Wigner distribution for a two-mode entangled state generated by an optical parametric oscillator

    SciTech Connect

    Dechoum, K.; Hahn, M. D.; Khoury, A. Z.

    2010-04-15

    We derive the steady-state solution of the Fokker-Planck equation that describes the dynamics of the nondegenerate optical parametric oscillator in the truncated Wigner representation of the density operator. We assume that the pump mode is strongly damped, which permits its adiabatic elimination. When the elimination is correctly executed, the resulting stochastic equations contain multiplicative noise terms and do not admit a potential solution. However, we develop a heuristic scheme leading to a satisfactory steady-state solution. This provides a clear view of the intracavity two-mode entangled state valid in all operating regimes of the optical parametric oscillator. A non-Gaussian distribution is obtained for the above threshold solution.

  6. Generation of microseconds-duration square pulses in a passively mode-locked fiber laser

    NASA Astrophysics Data System (ADS)

    Liu, Tonghui; Jia, Dongfang; Liu, Ying; Wang, Zhaoying; Yang, Tianxin

    2015-12-01

    An ultra-wide tunable square pulse operating in dissipative soliton resonance (DSR) region has been experimentally investigated in a passively mode-locked figure-of-eight fiber laser. In our experiment, by simply increasing the pump power, the pulse width can be tuned in an ultra-wide range from 135 ns to 2272 ns without wave-breaking while the peak power remains almost constant. The maximum output single pulse energy is 236.8 nJ at the pump power of 508 mW. A 960 m highly nonlinear fiber (HNLF) is employed to realize widely tunable square pulse in the DSR region. To the best of our knowledge, this is the widest tunable range of pulse width in any all-fiber passively mode-locked fiber laser.

  7. OpenGeneMed: a portable, flexible and customizable informatics hub for the coordination of next-generation sequencing studies in support of precision medicine trials.

    PubMed

    Palmisano, Alida; Zhao, Yingdong; Li, Ming-Chung; Polley, Eric C; Simon, Richard M

    2016-07-15

    Trials involving genomic-driven treatment selection require the coordination of many teams interacting with a great variety of information. The need of better informatics support to manage this complex set of operations motivated the creation of OpenGeneMed. OpenGeneMed is a stand-alone and customizable version of GeneMed (Zhao et al. GeneMed: an informatics hub for the coordination of next-generation sequencing studies that support precision oncology clinical trials. Cancer Inform 2015;14(Suppl 2):45), a web-based interface developed for the National Cancer Institute Molecular Profiling-based Assignment of Cancer Therapy (NCI-MPACT) clinical trial coordinated by the NIH. OpenGeneMed streamlines clinical trial management and it can be used by clinicians, lab personnel, statisticians and researchers as a communication hub. It automates the annotation of genomic variants identified by sequencing tumor DNA, classifies the actionable mutations according to customizable rules and facilitates quality control in reviewing variants. The system generates summarized reports with detected genomic alterations that a treatment review team can use for treatment assignment. OpenGeneMed allows collaboration to happen seamlessly along the clinical pipeline; it helps reduce errors made transferring data between groups and facilitates clear documentation along the pipeline. OpenGeneMed is distributed as a stand-alone virtual machine, ready for deployment and use from a web browser; its code is customizable to address specific needs of different clinical trials and research teams. Examples on how to change the code are provided in the technical documentation distributed with the virtual machine. In summary, OpenGeneMed offers an initial set of features inspired by our experience with GeneMed, a system that has been proven to be efficient and successful for coordinating the application of next-generation sequencing in the NCI-MPACT trial.

  8. Separation of spatial-temporal patterns ('climatic modes') by combined analysis of really measured and generated numerically vector time series

    NASA Astrophysics Data System (ADS)

    Feigin, A. M.; Mukhin, D.; Volodin, E. M.; Gavrilov, A.; Loskutov, E. M.

    2013-12-01

    The new method of decomposition of the Earth's climate system into well separated spatial-temporal patterns ('climatic modes') is discussed. The method is based on: (i) generalization of the MSSA (Multichannel Singular Spectral Analysis) [1] for expanding vector (space-distributed) time series in basis of spatial-temporal empirical orthogonal functions (STEOF), which makes allowance delayed correlations of the processes recorded in spatially separated points; (ii) expanding both real SST data, and longer by several times SST data generated numerically, in STEOF basis; (iii) use of the numerically produced STEOF basis for exclusion of 'too slow' (and thus not represented correctly) processes from real data. The application of the method allows by means of vector time series generated numerically by the INM RAS Coupled Climate Model [2] to separate from real SST anomalies data [3] two climatic modes possessing by noticeably different time scales: 3-5 and 9-11 years. Relations of separated modes to ENSO and PDO are investigated. Possible applications of spatial-temporal climatic patterns concept to prognosis of climate system evolution is discussed. 1. Ghil, M., R. M. Allen, M. D. Dettinger, K. Ide, D. Kondrashov, et al. (2002) "Advanced spectral methods for climatic time series", Rev. Geophys. 40(1), 3.1-3.41. 2. http://83.149.207.89/GCM_DATA_PLOTTING/GCM_INM_DATA_XY_en.htm 3. http://iridl.ldeo.columbia.edu/SOURCES/.KAPLAN/.EXTENDED/.v2/.ssta/

  9. Black phosphorus as a saturable absorber for generating mode-locked fiber laser in normal dispersion regime

    NASA Astrophysics Data System (ADS)

    Latiff, A. A.; Rusdi, M. F. M.; Hisyam, M. B.; Ahmad, H.; Harun, S. W.

    2016-11-01

    This paper reports a few-layer black phosphorus (BP) as a saturable absorber (SA) or phase-locker in generating modelocked pulses from a double-clad ytterbium-doped fiber laser (YDFL). We mechanically exfoliated the BP flakes from BP crystal through a scotch tape, and repeatedly press until the flakes thin and spread homogenously. Then, a piece of BP tape was inserted in the cavity between two fiber connectors end facet. Under 810 mW to 1320 mW pump power, stable mode-locked operation at 1085 nm with a repetition rate of 13.4 MHz is successfully achieved in normal dispersion regime. Before mode-locked operation disappears above maximum pump, the output power and pulse energy is about 80 mW and 6 nJ, respectively. This mode-locked laser produces peak power of 0.74 kW. Our work may validates BP SA as a phase-locker related to two-dimensional nanomaterials and pulsed generation in normal dispersion regime.

  10. ANGULAR MOMENTUM TRANSPORT BY ACOUSTIC MODES GENERATED IN THE BOUNDARY LAYER. I. HYDRODYNAMICAL THEORY AND SIMULATIONS

    SciTech Connect

    Belyaev, Mikhail A.; Rafikov, Roman R.; Stone, James M.

    2013-06-10

    The nature of angular momentum transport in the boundary layers of accretion disks has been one of the central and long-standing issues of accretion disk theory. In this work we demonstrate that acoustic waves excited by supersonic shear in the boundary layer serve as an efficient mechanism of mass, momentum, and energy transport at the interface between the disk and the accreting object. We develop the theory of angular momentum transport by acoustic modes in the boundary layer, and support our findings with three-dimensional hydrodynamical simulations, using an isothermal equation of state. Our first major result is the identification of three types of global modes in the boundary layer. We derive dispersion relations for each of these modes that accurately capture the pattern speeds observed in simulations to within a few percent. Second, we show that angular momentum transport in the boundary layer is intrinsically nonlocal, and is driven by radiation of angular momentum away from the boundary layer into both the star and the disk. The picture of angular momentum transport in the boundary layer by waves that can travel large distances before dissipating and redistributing angular momentum and energy to the disk and star is incompatible with the conventional notion of local transport by turbulent stresses. Our results have important implications for semianalytical models that describe the spectral emission from boundary layers.

  11. Strong-driving-assisted generation of two-mode nonclassical states and swap gate operation in trapped-ion cavity QED

    NASA Astrophysics Data System (ADS)

    Zheng, Xiao-Juan; Fang, Mao-Fa; Cai, Jian-Wu; Cao, Shuai; Liao, Xiang-Ping

    2006-11-01

    We propose a simple and efficient scheme to generate a nonclassical state of a quantum system, which is composed of the one-dimension trapped-one motion and a single-cavity field mode. We also generate two-mode SU(2) Schrödinger-cat states, entangled coherent states and squeezed cat states. In addition, we show that a quantum swap gate can be implemented if the vibration mode and cavity mode are used to represent separately a qubit. The distinct feature of the scheme is that it operates in the strong-excitation regime (Ω Gt ν), which greatly enhances operation speed.

  12. Molecular tectonics: pyridyl containing thiacalix[4]arene based tectons for the generation of 2- and 3-D silver coordination networks.

    PubMed

    Ovsyannikov, A; Lang, M N; Ferlay, S; Solovieva, S E; Antipin, I S; Konovalov, A I; Kyritsakas, N; Hosseini, M W

    2013-01-07

    Three new organic tectons (2–4) based on the p-tert-butylthiacalix[4]arene backbone, blocked in the 1,3-alternate conformation, bearing four pyridyl coordinating moieties, have been synthesised and characterised in the solid state. The ligands are positional isomers and differ by the position of the N atom on the pyridyl unit (ortho for 2, meta for 3 and para for 4). Their combination with the Ag+ cation leads, reproducibly, to the formation of 2- and 3-D infinite silver coordination networks. Independent of the nature of the anion, the combination of 2 offering four (N,S) type chelates with the Ag+ cation affords an unprecedented diamond type 3D network. Both 3 and 4, behaving as tetrakis monodentate ligands, lead to the formation of 2-D architectures.

  13. Hysteresis behavior of Kerr frequency comb generation in a high-quality-factor whispering-gallery-mode microcavity

    NASA Astrophysics Data System (ADS)

    Kato, Takumi; Chen-Jinnai, Akitoshi; Nagano, Takuma; Kobatake, Tomoya; Suzuki, Ryo; Yoshiki, Wataru; Tanabe, Takasumi

    2016-07-01

    A numerical and experimental study of Kerr frequency comb generation in a silica toroid microcavity is presented. We use a generalized mean-field Lugiato-Lefever equation and solve it with the split-step Fourier method. We observe that a stable mode-locked regime can be accessed when we reduce the input power after strong pumping due to the bistable nature of the nonlinear cavity system used. The experimental results agree well with the results of the numerical analysis, where we obtain a low-noise Kerr comb spectrum by gradually reducing the pumping input after strong pumping. This finding complements the results obtained by a previous wavelength scanning method and clarifies the procedure for achieving mode-locked states in such high-Q microcavity systems.

  14. Robust fractional order sliding mode control of doubly-fed induction generator (DFIG)-based wind turbines.

    PubMed

    Ebrahimkhani, Sadegh

    2016-07-01

    Wind power plants have nonlinear dynamics and contain many uncertainties such as unknown nonlinear disturbances and parameter uncertainties. Thus, it is a difficult task to design a robust reliable controller for this system. This paper proposes a novel robust fractional-order sliding mode (FOSM) controller for maximum power point tracking (MPPT) control of doubly fed induction generator (DFIG)-based wind energy conversion system. In order to enhance the robustness of the control system, uncertainties and disturbances are estimated using a fractional order uncertainty estimator. In the proposed method a continuous control strategy is developed to achieve the chattering free fractional order sliding-mode control, and also no knowledge of the uncertainties and disturbances or their bound is assumed. The boundedness and convergence properties of the closed-loop signals are proven using Lyapunov׳s stability theory. Simulation results in the presence of various uncertainties were carried out to evaluate the effectiveness and robustness of the proposed control scheme.

  15. Syntheses and crystal structures of two novel alkaline uranyl chromates A{sub 2}(UO{sub 2})(CrO{sub 4}){sub 2} (A=Rb, Cs) with bidentate coordination mode of uranyl ions by chromate anions

    SciTech Connect

    Siidra, Oleg I.

    2012-03-15

    Single crystals of Cs{sub 2}(UO{sub 2})(CrO{sub 4}){sub 2} and Rb{sub 2}(UO{sub 2})(CrO{sub 4}){sub 2} were prepared by solid state reactions. The structures are based upon the [(UO{sub 2})(CrO{sub 4}){sub 2}]{sup 2-} chains. Within the chains, UrO{sub 5} pentagonal bipyramids (Ur=uranyl) form Ur{sub 2}O{sub 8} dimers, which are linked via CrO{sub 4} tetrahedra into one-dimensional chains. The CrO{sub 4} tetrahedra coordinate uranyl ions in both mono- and bidentate fashion, which is unusual for uranyl chromates. The bidentate coordination has a strong influence upon geometrical parameters of both U and Cr coordination polyhedra. The conformation of the chains in 1 and 2 is different due to the different size of the Cs{sup +} and Rb{sup +} cations. - Graphical abstract: Uranyl chromate chain with monodentate and bidentate coordination mode of uranyl cations by CrO{sub 4} tetrahedra in Cs{sub 2}(UO{sub 2})(CrO{sub 4}){sub 2}. Highlights: Black-Right-Pointing-Pointer Single crystals of novel uranyl chromates were prepared by solid state reactions. Black-Right-Pointing-Pointer The CrO{sub 4} tetrahedra coordinate uranyl ions in both mono- and bidentate fashion. Black-Right-Pointing-Pointer The bidentate coordination has a strong influence upon geometrical parameters.

  16. ITER Plasma at Electron Cyclotron Frequency Domain: Stimulated Raman Scattering off Gould-Trivelpiece Modes and Generation of Suprathermal Electrons and Energetic Ions

    NASA Astrophysics Data System (ADS)

    Stefan, V. Alexander

    2011-04-01

    Stimulated Raman scattering in the electron cyclotron frequency range of the X-Mode and O-Mode driver with the ITER plasma leads to the ``tail heating'' via the generation of suprathermal electrons and energetic ions. The scattering off Trivelpiece-Gould (T-G) modes is studied for the gyrotron frequency of 170GHz; X-Mode and O-Mode power of 24 MW CW; on-axis B-field of 10T. The synergy between the two-plasmon decay and Raman scattering is analyzed in reference to the bulk plasma heating. Supported in part by Nikola TESLA Labs, La Jolla, CA

  17. A CMOS current-mode log(x) and log(1/x) functions generator

    NASA Astrophysics Data System (ADS)

    Al-Absi, Munir A.; Al-Tamimi, Karama M.

    2014-08-01

    A novel Complementary Metal Oxide Semiconductor (CMOS) current-mode low-voltage and low-power controllable logarithmic function circuit is presented. The proposed design utilises one Operational Transconductance Amplifier (OTA) and two PMOS transistors biased in weak inversion region. The proposed design provides high dynamic range, controllable amplitude, high accuracy and is insensitive to temperature variations. The circuit operates on a ±0.6 V power supply and consumes 0.3 μW. The functionality of the proposed circuit was verified using HSPICE with 0.35 μm 2P4M CMOS process technology.

  18. Generation of 28-fs pulses from a mode-locked ytterbium fiber oscillator.

    PubMed

    Zhou, Xiangyu; Yoshitomi, Dai; Kobayashi, Yohei; Torizuka, Kenji

    2008-05-12

    An ultrashort-pulse, mode-locked ytterbium-doped fiber laser has been developed. The group-delay dispersion was compensated with a grating pair inside the cavity. A broad spectrum from 1000-nm to 1120-nm was obtained without intracavity compensation of third-order dispersion. A 0.7-nJ pulse as short as 28.3 fs was obtained with a repetition rate of 80 MHz. To our knowledge, this is the shortest pulse reported from an Yb fiber laser oscillator.

  19. Porous nano-structured Co3O4 anode materials generated from coordination-driven self-assembled aggregates for advanced lithium ion batteries.

    PubMed

    Ge, Danhua; Geng, Hongbo; Wang, Jiaqing; Zheng, Junwei; Pan, Yue; Cao, Xueqin; Gu, Hongwei

    2014-08-21

    A simple and scalable coordination-derived method for the synthesis of porous Co3O4 hollow nanospheres is described here. The initially formed coordination-driven self-assembled aggregates (CDSAAs) could act as the precursor followed by calcination treatment. Then the porous hollow Co3O4 nanospheres are obtained, in which the primary Co3O4 nanoparticles are inter-dispersed. When the nanospheres are used as anode materials for lithium storage, they show excellent coulombic efficiency, high lithium storage capacity and superior cycling performance. In view of the facile synthesis and excellent electrochemical performance obtained, this protocol to fabricate special porous hollow frameworks could be further extended to other metal oxides and is expected to improve the practicality of superior cycle life anode materials with large volume excursions for the development of the next generation of LIBs.

  20. Ultra-broadband dissipative soliton and noise-like pulse generation from a normal dispersion mode-locked Tm-doped all-fiber laser.

    PubMed

    Sobon, Grzegorz; Sotor, Jaroslaw; Martynkien, Tadeusz; Abramski, Krzysztof M

    2016-03-21

    We report generation of ultra-broadband dissipative solitons and noise-like pulses from a simple, fully fiberized mode-locked Tm-doped fiber laser. The oscillator operates in the normal net dispersion regime and is mode-locked via nonlinear polarization evolution. Depending on the cavity dispersion, the laser was capable of generating 60 nm or 100 nm broad dissipative solitons. These are the broadest spectra generated from a normal dispersion mode-locked Tm-doped fiber laser so far. The same oscillator might also operate in the noise-like pulse regime with extremely broad emission spectra (over 300 nm), which also significantly outperforms the previous reports.

  1. Mode-locked fiber laser with cascaded generation of coherent Raman dissipative solitons

    NASA Astrophysics Data System (ADS)

    Kharenko, Denis S.; Bednyakova, Anastasia E.; Podivilov, Evgenii V.; Fedoruk, Mikhail P.; Apolonskiy, Alexander A.; Babin, Sergey A.

    2016-03-01

    We experimentally demonstrate a cascaded generation of a conventional dissipative soliton (DS) at 1020 nm and Raman dissipative solitons (RDS) of the first (1065 nm) and second (1115 nm) orders inside a common fiber laser cavity. The generated high-energy pulses are shown to be linearly-chirped and compressible to 200-300 fs durations for all wavelengths. Moreover, the pulses are mutually coherent that has been confirmed by efficient coherent combining exhibiting ~75 fs and <40 fs interference fringes within the combined pulse envelope of a DS with the first-order RDS and the second-order RDS respectively. The numerical simulation was performed with sinusoidal (soft) and step-like (hard) spectral filters and took into account the discreetness of the laser elements. Shown that even higher degree of coherence and shorter pulses could be achieved with hard spectral filtering. This approach opens the door towards cascaded generation of multiple coherent dissipative solitons in a broad spectral range (so-called dissipative soliton comb). The demonstrated source of coherent dissipative solitons can improve numerous areas such as frequency comb generation, pulse synthesis, biomedical imaging and the generation of coherent mid-infrared supercontinuum.

  2. Advances in generation of high-repetition-rate burst mode laser output.

    PubMed

    Jiang, Naibo; Webster, Matthew C; Lempert, Walter R

    2009-02-01

    It is demonstrated that the incorporation of variable pulse duration flashlamp power supplies into an Nd:YAG burst mode laser system results in very substantial increases in the realizable energy per pulse, the total pulse train length, and uniformity of the intensity envelope. As an example, trains of 20 pulses at burst frequencies of 50 and 20 kHz are demonstrated with individual pulse energy at 1064 nm of 220 and 400 mJ, respectively. Conversion efficiency to the second- (532 nm) and third- (355 nm) harmonic wavelengths of approximately 50% and 35-40%, respectively, is also achieved. Use of the third-harmonic output of the burst mode laser as a pump source for a simple, home built optical parametric oscillator (OPO) produces pulse trains of broadly wavelength tunable output. Sum-frequency mixing of OPO signal output at 622 nm with residual output from the 355 nm pump beam is shown to produce uniform bursts of tunable output at approximately 226 nm, with individual pulse energy of approximately 0.5 mJ. Time-correlated NO planar laser induced fluorescence (PLIF) image sequences are obtained in a Mach 3 wind tunnel at 500 kHz, representing, to our knowledge, the first demonstration of NO PLIF imaging at repetition rates exceeding tens of hertz.

  3. High-power, single-longitudinal-mode terahertz-wave generation pumped by a microchip Nd:YAG laser [Invited].

    PubMed

    Hayashi, Shin'ichiro; Nawata, Koji; Sakai, Hiroshi; Taira, Takunori; Minamide, Hiroaki; Kawase, Kodo

    2012-01-30

    We report on the development of a high-peak-power, single-longitudinal-mode and tunable injection-seeded terahertz-wave parametric generator using MgO:LiNbO3, which operates at room temperature. The high peak power (> 120 W) is enough to allow easy detection by commercial and calibrated pyroelectric detectors, and the spectral resolution (< 10 GHz) is the Fourier transform limit of the sub-nanosecond terahertz-wave pulse. The tunability (1.2-2.8 THz) and the small footprint size (A3 paper, 29.7 × 42 cm) are suitable for a variety of applications.

  4. ANGULAR MOMENTUM TRANSPORT BY ACOUSTIC MODES GENERATED IN THE BOUNDARY LAYER. II. MAGNETOHYDRODYNAMIC SIMULATIONS

    SciTech Connect

    Belyaev, Mikhail A.; Rafikov, Roman R.; Stone, James M.

    2013-06-10

    We perform global unstratified three-dimensional magnetohydrodynamic simulations of an astrophysical boundary layer (BL)-an interface region between an accretion disk and a weakly magnetized accreting object such as a white dwarf-with the goal of understanding the effects of magnetic field on the BL. We use cylindrical coordinates with an isothermal equation of state and investigate a number of initial field geometries including toroidal, vertical, and vertical with zero net flux. Our initial setup consists of a Keplerian disk attached to a non-rotating star. In a previous work, we found that in hydrodynamical simulations, sound waves excited by shear in the BL were able to efficiently transport angular momentum and drive mass accretion onto the star. Here we confirm that in MHD simulations, waves serve as an efficient means of angular momentum transport in the vicinity of the BL, despite the magnetorotational instability (MRI) operating in the disk. In particular, the angular momentum current due to waves is at times larger than the angular momentum current due to MRI. Our results suggest that angular momentum transport in the BL and its vicinity is a global phenomenon occurring through dissipation of waves and shocks. This point of view is quite different from the standard picture of transport by a local anomalous turbulent viscosity. In addition to angular momentum transport, we also study magnetic field amplification within the BL. We find that the field is indeed amplified in the BL, but only by a factor of a few, and remains subthermal.

  5. Suppression of beam induced pulse shortening modes in high power RF generator TW output structures

    SciTech Connect

    Haimson, J.; Mecklenburg, B.

    1992-12-31

    Several different style 11.4 GHz relativistic klystrons, operating with beam pulse widths of 50 ns and using large aperture, tapered phase-velocity TW structures,` have recently demonstrated output RF power levels in the range of 100 to 300 MW without breakdown or pulse shortening. To extend this performance into the long pulse regime (1 {mu}s) or to demonstrate a threefold increase in output power by using higher currents, the existing TW circuit designs must be modified (a) to reduce the cavity maximum surface E-fields by a factor of 2 to 3, and (b) to elevate the current threshold values of the beam induced higher order modes (HOM) to ensure avoidance of RF pulse shortening and associated instabilities. A technique for substantially elevating this threshold current is described, and microwave data and photographs are presented showing the degree of HOM damping achieved in a recently constructed 11.4 GHz TW structure.

  6. Compact optical displacement sensing by detection of microwave signals generated from a monolithic passively mode-locked laser under feedback

    NASA Astrophysics Data System (ADS)

    Simos, Christos; Simos, Hercules; Nikas, Thomas; Syvridis, Dimitris

    2015-05-01

    A monolithic passively mode-locked laser is proposed as a compact optical sensor for displacements and vibrations of a reflecting object. The sensing principle relies on the change of the laser repetition frequency that is induced by optical feedback from the object under measurement. It has been previously observed that, when a semiconductor passively mode locked laser receives a sufficient level of optical feedback from an external reflecting surface it exhibits a repetition frequency that is no more determined by the mode-locking rule of the free-running operation but is imposed by the length of the external cavity. Therefore measurement of the resulting laser repetition frequency under self-injection permits the accurate and straightforward determination of the relative position of the reflecting object. The system has an inherent wireless capability since the repetition rate of the laser can be wirelessly detected by means of a simple antenna which captures the microwave signal generated by the saturable absorber and is emitted through the wiring of the laser. The sensor setup is very simple as it requires few optical components besides the laser itself. Furthermore, the deduction of the relative position of the reflecting object is straightforward and does not require any processing of the detected signal. The proposed sensor has a theoretical sub-wavelength resolution and its performance depends on the RF linewidth of the laser and the resolution of the repetition frequency measurement. Other physical parameters that induce phase changes of the external cavity could also be quantified.

  7. A numerical model for ocean ultra-low frequency noise: wave-generated acoustic-gravity and Rayleigh modes.

    PubMed

    Ardhuin, Fabrice; Lavanant, Thibaut; Obrebski, Mathias; Marié, Louis; Royer, Jean-Yves; d'Eu, Jean-François; Howe, Bruce M; Lukas, Roger; Aucan, Jerome

    2013-10-01

    The generation of ultra-low frequency acoustic noise (0.1 to 1 Hz) by the nonlinear interaction of ocean surface gravity waves is well established. More controversial are the quantitative theories that attempt to predict the recorded noise levels and their variability. Here a single theoretical framework is used to predict the noise level associated with propagating pseudo-Rayleigh modes and evanescent acoustic-gravity modes. The latter are dominant only within 200 m from the sea surface, in shallow or deep water. At depths larger than 500 m, the comparison of a numerical noise model with hydrophone records from two open-ocean sites near Hawaii and the Kerguelen islands reveal: (a) Deep ocean acoustic noise at frequencies 0.1 to 1 Hz is consistent with the Rayleigh wave theory, in which the presence of the ocean bottom amplifies the noise by 10 to 20 dB; (b) in agreement with previous results, the local maxima in the noise spectrum support the theoretical prediction for the vertical structure of acoustic modes; and (c) noise level and variability are well predicted for frequencies up to 0.4 Hz. Above 0.6 Hz, the model results are less accurate, probably due to the poor estimation of the directional properties of wind-waves with frequencies higher than 0.3 Hz.

  8. Generation of Non-Inductive H-Mode Plasmas with 30 MHz Fast Wave Heating in NSTX-U

    NASA Astrophysics Data System (ADS)

    Taylor, G.; Bertelli, N.; Gerhardt, S. P.; Hosea, J. C.; Mueller, D.; Perkins, R. J.; Poli, F. M.; Wilson, J. R.; Raman, R.

    2016-10-01

    A Fusion Nuclear Science Facility based on a spherical tokamak must generate the plasma current (Ip) with little or no central solenoid field. The NSTX-U non-inductive (NI) plasma research program is addressing this goal by developing NI start-up, ramp-up and sustainment scenarios separately. 4 MW of 30 MHz fast wave power is predicted to ramp Ip to 400 kA, a level sufficient to avoid significant shine-through of 90 keV ions from neutral beam injection. In 2010, experiments in NSTX demonstrated that 1.4 MW of 30 MHz high-harmonic fast wave (HHFW) power could generate an Ip = 300 kA H-mode discharge with a NI Ip fraction, fNI, around 0.7 at the maximum axial toroidal field (BT(0)) in NSTX of 0.55 T. NSTX-U is a major upgrade of NSTX that will eventually allow the generation of plasmas with BT(0) up to 1 T. Full wave simulations of 30 MHz HHFW heating in NSTX-U predict reduced FW power loss in the plasma edge as BT(0) is increased. HHFW experiments this year aim to couple 3 - 4 MW of 30 MHz HHFW power into an Ip = 250 - 350 kA plasma with BT(0) up to 0.75 T to generate a fNI = 1 H-mode plasma. These experiments should benefit from the improved fast wave coupling predicted at higher BT(0) in NSTX-U. Work supported by USDOE Contract No. DE-AC02-09CH11466.

  9. Broadband continuum generation in mode-locked lasers with phase-matched output couplers.

    PubMed

    Chia, Shih-Hsuan; Chen, Li-Jin; Zhang, Qing; Mücke, Oliver D; Chang, Guoqing; Kärtner, Franz X

    2014-03-15

    The concept of intracavity phase matching is proposed and demonstrated both theoretically and experimentally with a broadband phase-matched dielectric output coupler for linear-cavity few-cycle Ti:sapphire oscillators. The spectrum in the matched wavelength range is enhanced by >10  dB while maintaining good beam quality via resonantly enhanced continuum generation. The enhanced spectral components can be continuously tuned by varying the intracavity dispersion. Because dielectric coatings offer flexible design capabilities, this approach is applicable to various lasers with different gain media to obtain custom-tailored spectra, which have the potential to benefit several applications, such as shorter pulse generation, seeding of ytterbium lasers for pumping optical parametric amplifiers, and direct f-2f detection of the carrier-envelope phase.

  10. Dynamic generation of Ince-Gaussian modes with a digital micromirror device

    SciTech Connect

    Ren, Yu-Xuan; Fang, Zhao-Xiang; Chen, Yue; Lu, Rong-De; Gong, Lei; Huang, Kun

    2015-04-07

    Ince-Gaussian (IG) beam with elliptical profile, as a connection between Hermite-Gaussian (HG) and Laguerre-Gaussian (LG) beams, has showed unique advantages in some applications such as quantum entanglement and optical micromanipulation. However, its dynamic generation with high switching frequency is still challenging. Here, we experimentally reported the quick generation of Ince-Gaussian beam by using a digital micro-mirror device (DMD), which has the highest switching frequency of 5.2 kHz in principle. The configurable properties of DMD allow us to observe the quasi-smooth variation from LG (with ellipticity ε=0) to IG and HG (ε=∞) beam. This approach might pave a path to high-speed quantum communication in terms of IG beam. Additionally, the characterized axial plane intensity distribution exhibits a 3D mould potentially being employed for optical micromanipulation.

  11. Broad and ultra-flattened supercontinuum generation in the visible wavelengths based on the fundamental mode of photonic crystal fibre with central holes

    NASA Astrophysics Data System (ADS)

    Yuan, Jin-Hui; Sang, Xin-Zhu; Yu, Chong-Xiu; Xin, Xiang-Jun; Shen, Xiang-Wei; Zhang, Jin-Long; Zhou, Gui-Yao; Li, Shu-Guang; Hou, Lan-Tian

    2011-05-01

    By coupling a train of femtosecond pulses with 100 fs pulse width at a repetition rate of 76 MHz generated by a mode-locked Ti: sapphire laser into the fundamental mode of photonic crystal fibre (PCF) with central holes fabricated through extracting air from the central hole, the broad and ultra-flattened supercontinuum (SC) in the visible wavelengths is generated. When the fundamental mode experiences an anomalous dispersion regime, three phases in the SC generation process are primarily presented. The SC generation (SCG) in the wavelength range from 470 nm to 805 nm does not emerge significant ripples due to a higher pump peak power and the corresponding mode fields at different wavelengths are observed using Bragg gratings. The relative intensity fluctuations of output spectrum in the wavelength ranges of 530 nm to 640 nm and 543 nm to 590 nm are only 0.028 and 0.0071, respectively.

  12. Kinetic Modeling Sheds Light on the Mode of Action of Recombinant Factor VIIa on Thrombin Generation

    DTIC Science & Technology

    2011-01-01

    numerical model to generate activated factor VII (FVIIa) titration curves in the cases of normal blood composition, hemophilia A and B blood, blood...as a hemostatic agent for patients with hemophilia , congenital FVII deficiency, and Glanzmann’s thrombocytopenia [3]. Following its initial approval...normal blood composition, hemophilia A and B blood, blood lacking factor VII, blood lacking tissue factor pathway inhibitor, and diluted blood. We

  13. Impacts of propagating, frustrated and surface modes on radiative, electrical and thermal losses in nanoscale-gap thermophotovoltaic power generators.

    PubMed

    Bernardi, Michael P; Dupré, Olivier; Blandre, Etienne; Chapuis, Pierre-Olivier; Vaillon, Rodolphe; Francoeur, Mathieu

    2015-06-26

    The impacts of radiative, electrical and thermal losses on the performances of nanoscale-gap thermophotovoltaic (nano-TPV) power generators consisting of a gallium antimonide cell paired with a broadband tungsten and a radiatively-optimized Drude radiator are analyzed. Results reveal that surface mode mediated nano-TPV power generation with the Drude radiator outperforms the tungsten radiator, dominated by frustrated modes, only for a vacuum gap thickness of 10 nm and if both electrical and thermal losses are neglected. The key limiting factors for the Drude- and tungsten-based devices are respectively the recombination of electron-hole pairs at the cell surface and thermalization of radiation with energy larger than the cell absorption bandgap. A design guideline is also proposed where a high energy cutoff above which radiation has a net negative effect on nano-TPV power output due to thermal losses is determined. It is shown that the power output of a tungsten-based device increases by 6.5% while the cell temperature decreases by 30 K when applying a high energy cutoff at 1.45 eV. This work demonstrates that design and optimization of nano-TPV devices must account for radiative, electrical and thermal losses.

  14. Impacts of propagating, frustrated and surface modes on radiative, electrical and thermal losses in nanoscale-gap thermophotovoltaic power generators

    PubMed Central

    Bernardi, Michael P.; Dupré, Olivier; Blandre, Etienne; Chapuis, Pierre-Olivier; Vaillon, Rodolphe; Francoeur, Mathieu

    2015-01-01

    The impacts of radiative, electrical and thermal losses on the performances of nanoscale-gap thermophotovoltaic (nano-TPV) power generators consisting of a gallium antimonide cell paired with a broadband tungsten and a radiatively-optimized Drude radiator are analyzed. Results reveal that surface mode mediated nano-TPV power generation with the Drude radiator outperforms the tungsten radiator, dominated by frustrated modes, only for a vacuum gap thickness of 10 nm and if both electrical and thermal losses are neglected. The key limiting factors for the Drude- and tungsten-based devices are respectively the recombination of electron-hole pairs at the cell surface and thermalization of radiation with energy larger than the cell absorption bandgap. A design guideline is also proposed where a high energy cutoff above which radiation has a net negative effect on nano-TPV power output due to thermal losses is determined. It is shown that the power output of a tungsten-based device increases by 6.5% while the cell temperature decreases by 30 K when applying a high energy cutoff at 1.45 eV. This work demonstrates that design and optimization of nano-TPV devices must account for radiative, electrical and thermal losses. PMID:26112658

  15. Simultaneous generation of wavelength division multiplexing PON and RoF signals using a hybrid mode-locked laser

    NASA Astrophysics Data System (ADS)

    Aldaya, Ivan; Campuzano, Gabriel; Castañón, Gerardo

    2015-06-01

    The use of millimeter-wave (mm-wave) frequencies has been proposed to overcome the imminent saturation of the ultra high frequency band, justifying research on radio over fiber (RoF) networks as an inexpensive and green solution to distribute multi-Gbps signals. Coincidently, telecommunication operators are investing a significant effort to deploy their passive optical network (PON) infrastructure closer to the users. In this work, we present a novel cost-efficient architecture based on a hybrid mode locked laser capable to simultaneously generate up-to 5 wavelength division multiplexing PON and RoF channels, being compatible with the 50-GHz ITU frequency grid. We analyze the limits of operation of our proposed architecture considering the high modal relative intensity noise induced by mode partition noise, as well as fiber impairments, such as chromatic dispersion and nonlinearities. The feasibility of generation and transmission of 5×10-Gbps PON and 5×5-Gbps RoF using orthogonal frequency division multiplexing up to 50 km has been demonstrated through realistic numerical simulations.

  16. Generation of Small-Mode Particles via Nucleation of Meteoric Dust in the Upper Haze of Venus

    NASA Astrophysics Data System (ADS)

    Yung, Yuk; Gao, P.; Zhang, X.; Crisp, D.; Bardeen, C. G.

    2012-10-01

    Observations by the SPICAV/SOIR instruments aboard Venus Express has revealed that the Upper Haze of Venus is populated by two particle modes, as reported by Wilquet et al. (J. Geophys. Res., 114, E00B42, 13pp, 2009). In this work we posit that the large mode is due to the upwelling of cloud particles, while the smaller mode is generated by the nucleation of meteoric dust. We test this hypothesis by using version 3.0 of the Community Aerosol and Radiation Model for Atmospheres, first developed by Turco et al. (J. Atmos. Sci., 36, 699-717, 1979) and upgraded by Bardeen et al. (The CARMA 3.0 microphysics package in CESM, Whole Atmosphere Working Group Meeting, 2011). Using the meteoric dust production profile of Kalashnikova et al. (Geophys. Res. Lett., 27, 3293-3296, 2000), the sulfur/sulfate condensation nuclei production profile of Imamura and Hashimoto (J. Atmos. Sci., 58, 3597-3612, 2001), and sulfuric acid vapour production profile of Zhang et al. (Icarus, 217, 714-739, 2012), we numerically simulate a column of the Venus atmosphere from 40 to 100 km above the surface. Our aerosol number density results agree well with Pioneer Venus data from Knollenberg and Hunten (J. Geophys. Res., 85, 8039-8058, 1980), while our gas distribution results match that of Kolodner and Steffes (Icarus, 132, 151-169, 1998). There is a mediocre agreement between our cloud deck size distribution and Pioneer Venus data. The Upper Haze size distribution shows two lognormal distributions overlapping each other, possibly indicating the presence of two modes, though more analysis is required at this time. Finally, we treat the simulated aerosol particles as Mie scatterers and compute their optical parameters. The results show a minimum in the optical depth at a wavelength of 300 nm, comparable to the results of Lacis (J. Atmos. Sci., 32, 1107-1124, 1975).

  17. An optical pulse width modulation generator based on the injection-locking property of single mode FP-LD

    NASA Astrophysics Data System (ADS)

    Tran, Quoc Hoai; Nakarmi, Bikash; Won, Yong Hyub

    2013-03-01

    A novel simple optical pulse width modulation generator (OPWMG) based on injection-locking property of a single mode FP-LD (SMFP-LD) has been proposed and experimentally verified. The OPWMG consists of a SMFP-LD (which acts as comparator), an optical sinusoidal wave source (analog input), and a continuous optical beam (control signal). The power required for fully injection-locking the SMFP-LD acts as the referent power whereas the combination power of continuous optical beam and analog optical sinusoidal signals work as control signals for changing the duty cycle of the proposed OPWMG. The presence of only continuous optical beam is not sufficient to suppress the dominant mode of SMFP-LD with high ON/OFF contrast ratio; however, the application of additional sinusoidal wave of constant amplitude and frequency, the dominant mode of SMFP-LD can be suppressed for the certain time window. Since, injection-locking power is dependent with the combined power of input injected continuous beam and sinusoidal optical wave, the time window of injection-locking can be varied by changing input beam power which provides different duty cycle of 13% to 68% at the output. Current available schemes for generating PWM signals are in electrical domain, hence, they need to convert electrical signals into optical domain by using expensive O/E converters for application in optical control and signal processing. The proposed OPWMG scheme has several advantages, such as low cost, low power consumption (~0.5 mW) which can be used for various applications where the effect of EMI/EMR is considered as an important factor such as control circuit for high voltage converters in power plant and electrical vehicles.

  18. One-dimensional coordination polymers generated from a new triazole bridging ligand and HgX2 (X = Cl, Br and I): characterization and luminescent properties.

    PubMed

    Qin, Na; Zhao, Chao-Wei; Ma, Jian-Ping; Liu, Qi-Kui; Dong, Yu-Bin

    2012-06-01

    The new 4-amino-1,2,4-triazole asymmetric bridging ligand 4-amino-5-(pyridin-3-yl)-3-[4-(pyridin-4-yl)phenyl]-4H-1,2,4-triazole (L) has been used to generate three novel isomorphic one-dimensional coordination polymers, viz. catena-poly[[tris[dichloridomercury(II)]-bis{μ(3)-4-amino-5-(pyridin-3-yl)-3-[4-(pyridin-4-yl)phenyl]-4H-1,2,4-triazole}] acetonitrile monosolvate], {[Hg(3)Cl(6)(C(18)H(14)N(6))(2)]·CH(3)CN}(n), (I), and the bromido, {[Hg(3)Br(6)(C(18)H(14)N(6))(2)]·CH(3)CN}(n), (II), and iodido, {[Hg(3)I(6)(C(18)H(14)N(6))(2)]·CH(3)CN}(n), (III), analogs. The asymmetric ligand acts as a tridentate ligand to coordinate the three different Hg(II) centers (two of which are symmetry-related). Two ligands and two symmetry-related Hg(II) centers form centrosymmetric rectangular units which are linked into one-dimensional chains via the other unique Hg atoms, which sit on mirror planes. The chains are elaborated into a three-dimensional structure via interchain hydrogen bonds. The acetonitrile solvent molecules are located in ellipsoidal cavities. The luminescent character of these three coordination complexes was investigated in the solid state.

  19. Multiple-Component Crystal Fabric Measurements from Acoustically-Generated Normal Modes in Borehole

    NASA Astrophysics Data System (ADS)

    Kluskiewicz, D. J.; Waddington, E. D.; McCarthy, M.; Anandakrishnan, S.; Voigt, D.; Matsuoka, K.

    2014-12-01

    Sound wave velocities in ice are a proxy of crystal orientation fabric. Because p- and s-waves respectively travel faster and slower in the direction of an ice crystal c-axis, the velocities of these waves in a fabric are related to the clustering of ice crystal c-axes in the direction of wave propagation. Previous sonic logs at Dome C, NGRIP, WAIS, and NEEM have inferred a single component fabric description from the velocities of vertically-propagating p-waves around each ice core borehole. These records supplement thin-section measurements of crystal fabric by sampling larger numbers of crystals in a depth-continuous log. Observations of azimuthally anisotropic vertical-girdle fabrics at ice-core sites such as WAIS, NGRIP, and EDML underly a benefit for logging methods that are sensitive to such fabrics. We present a theoretical framework for using borehole flexural modes to measure azimuthal crystal-fabric anisotropy, and describe ongoing efforts to develop a sonic logging tool for this purpose. We also present data from p-wave logs and thin section measurements at the WAIS Divide, and describe how a flexural wave log could supplement the existing measurements.

  20. Numerical investigation of mid-infrared Raman soliton source generation in endless single mode fluoride fibers

    SciTech Connect

    Liu, Lai; Qin, Guan-Shi Tian, Qi-jun; Zhao, Dan; Qin, Wei-Ping

    2014-04-28

    We numerically investigate Raman soliton generation in a fluoride photonic crystal fiber (PCF) pumped by 1.93 μm femtosecond fiber lasers in order to get widely tunable laser source in the mid-infrared region. The simulated results show that a continuously tunable range (1.93 ∼ 3.95 μm) over 2000 nm is achieved in 1-m-long fluoride PCF pumped by a 1.93 μm femtosecond fiber laser with a pulse width of 200 fs. The power conversion efficiency is also calculated and the maximum efficiency can be up to 84.27%.

  1. Analysis of BaBar data for three meson tau decay modes using the Tauola generator

    SciTech Connect

    Shekhovtsova, Olga

    2014-11-24

    The hadronic current for the τ⁻ → π⁻π⁺π⁻ντ decay calculated in the framework of the Resonance Chiral Theory with an additional modification to include the σ meson is described. In addition, implementation into the Monte Carlo generator Tauola and fitting strategy to get the model parameters using the one-dimensional distributions are discussed. The results of the fit to one-dimensional mass invariant spectrum of the BaBar data are presented.

  2. Analysis of BaBar data for three meson tau decay modes using the Tauola generator

    DOE PAGES

    Shekhovtsova, Olga

    2014-11-24

    The hadronic current for the τ⁻ → π⁻π⁺π⁻ντ decay calculated in the framework of the Resonance Chiral Theory with an additional modification to include the σ meson is described. In addition, implementation into the Monte Carlo generator Tauola and fitting strategy to get the model parameters using the one-dimensional distributions are discussed. The results of the fit to one-dimensional mass invariant spectrum of the BaBar data are presented.

  3. TLR9-dependent recognition of MCMV by IPC and DC generates coordinated cytokine responses that activate antiviral NK cell function.

    PubMed

    Krug, Anne; French, Anthony R; Barchet, Winfried; Fischer, Jens A A; Dzionek, Andrzej; Pingel, Jeanette T; Orihuela, Michael M; Akira, Shizuo; Yokoyama, Wayne M; Colonna, Marco

    2004-07-01

    Natural interferon-producing cells (IPC) respond to viruses by secreting type I interferon (IFN) and interleukin-12 (IL-12). Toll-like receptor (TLR) 9 mediates IPC recognition of some of these viruses in vitro. However, whether TLR9-induced activation of IPC is necessary for an effective antiviral response in vivo is not clear. Here, we demonstrate that IPC and dendritic cells (DC) recognize murine cytomegalovirus (MCMV) through TLR9. TLR9-mediated cytokine secretion promotes viral clearance by NK cells that express the MCMV-specific receptor Ly49H. Although depletion of IPC leads to a drastic reduction of the IFN-alpha response, this allows other cell types to secrete IL-12, ensuring normal IFN-gamma and NK cell responses to MCMV. We conclude that the TLR9/MyD88 pathway mediates antiviral cytokine responses by IPC, DC, and possibly other cell types, which are coordinated to promote effective NK cell function and MCMV clearance.

  4. Numerical Simulation of the Generation of Axisymmetric Mode Jet Screech Tones

    NASA Technical Reports Server (NTRS)

    Shen, Hao; Tam, Christopher K. W.

    1998-01-01

    An imperfectly expanded supersonic jet, invariably, radiates both broadband noise and discrete frequency sound called screech tones. Screech tones are known to be generated by a feedback loop driven by the large scale instability waves of the jet flow. Inside the jet plume is a quasi-periodic shock cell structure. The interaction of the instability waves and the shock cell structure, as the former propagates through the latter, is responsible for the generation of the tones. Presently, there are formulas that can predict the tone frequency fairly accurately. However, there is no known way to predict the screech tone intensity. In this work, the screech phenomenon of an axisymmetric jet at low supersonic Mach number is reproduced by numerical simulation. The computed mean velocity profiles and the shock cell pressure distribution of the jet are found to be in good agreement with experimental measurements. The same is true with the simulated screech frequency. Calculated screech tone intensity and directivity at selected jet Mach number are reported in this paper. The present results demonstrate that numerical simulation using computational aeroacoustics methods offers not only a reliable way to determine the screech tone intensity and directivity but also an opportunity to study the physics and detailed mechanisms of the phenomenon by an entirely new approach.

  5. Second Harmonic Generation of Self-Mode-Locked СО2-Laser Radiation in GaSe and GaSeS Crystals

    NASA Astrophysics Data System (ADS)

    Genin, D. E.; Beloplotov, D. V.; Sitnikov, A. G.; Panchenko, A. N.; Sarkisov, S. Yu.; Chernyshov, A. I.

    2014-03-01

    A TEA CO2 laser generating at the wavelength λ = 10.6 μm in the modes of free lasing and self-mode-locking was used to obtain and compare second harmonic generation (SHG) in GaSe and GaSe0.7S0.3 crystals. With the self-mode-locked laser, a 5-times higher energy efficiency of SHG was obtained. The efficiency of SHG in the GaSe0.7S0.3 crystal and its second-order nonlinear susceptibility were estimated and compared with their values for undoped GaSe.

  6. Is there really a diagnostically useful relationship between the carbon-oxygen stretching frequencies in metal carboxylate complexes and their coordination mode?

    PubMed

    Martínez, David; Motevalli, Majid; Watkinson, Michael

    2010-01-14

    An investigation into the relationship between the asymmetric and symmetric stretching modes of ancillary carboxylate ligands and their mode of binding in a family of manganese(III) complexes of tetradentate N(2)O(2) Schiff base ligands, which includes comparison of an (18)O isotopically labelled derivative, has been undertaken. The results suggest that caution should be employed in using this technique to assign the binding mode of the carboxylate ligands in these complexes despite its very extensive use in the literature.

  7. Tempo and mode of genome evolution in a 50,000-generation experiment

    PubMed Central

    Ribeck, Noah; Deatherage, Daniel E.; Blanchard, Jeffrey L.; Dasgupta, Aurko; Wu, Gabriel C.; Wielgoss, Sébastien; Cruveiller, Stéphane; Médigue, Claudine; Schneider, Dominique

    2016-01-01

    Adaptation by natural selection depends on the rates, effects, and interactions of many mutations, making it difficult to determine what proportion of mutations in an evolving lineage are beneficial. We analysed 264 complete genomes from 12 Escherichia coli populations to characterize their dynamics over 50,000 generations. The populations that retained the ancestral mutation rate support a model where most fixed mutations are beneficial, the fraction of beneficial mutations declines as fitness rises, and neutral mutations accumulate at a constant rate. We also compared these populations to mutation-accumulation lines evolved under a bottlenecking regime that minimizes selection. Nonsynonymous mutations, intergenic mutations, insertions, and deletions are overrepresented in the long-term populations, further supporting the inference that most mutations that reached high frequency were favoured by selection. These results illuminate the shifting balance of forces that govern genome evolution in populations adapting to a new environment. PMID:27479321

  8. Tempo and mode of genome evolution in a 50,000-generation experiment.

    PubMed

    Tenaillon, Olivier; Barrick, Jeffrey E; Ribeck, Noah; Deatherage, Daniel E; Blanchard, Jeffrey L; Dasgupta, Aurko; Wu, Gabriel C; Wielgoss, Sébastien; Cruveiller, Stéphane; Médigue, Claudine; Schneider, Dominique; Lenski, Richard E

    2016-08-11

    Adaptation by natural selection depends on the rates, effects and interactions of many mutations, making it difficult to determine what proportion of mutations in an evolving lineage are beneficial. Here we analysed 264 complete genomes from 12 Escherichia coli populations to characterize their dynamics over 50,000 generations. The populations that retained the ancestral mutation rate support a model in which most fixed mutations are beneficial, the fraction of beneficial mutations declines as fitness rises, and neutral mutations accumulate at a constant rate. We also compared these populations to mutation-accumulation lines evolved under a bottlenecking regime that minimizes selection. Nonsynonymous mutations, intergenic mutations, insertions and deletions are overrepresented in the long-term populations, further supporting the inference that most mutations that reached high frequency were favoured by selection. These results illuminate the shifting balance of forces that govern genome evolution in populations adapting to a new environment.

  9. Quantitative analysis of backflow of reversible pump-turbine in generating mode

    NASA Astrophysics Data System (ADS)

    Liu, K. H.; Zhang, Y. N.; Li, J. W.; Xian, H. Z.

    2016-05-01

    Significant vibration and pressure fluctuations are usually observed when pump- turbine is operated during the off-design conditions, especially turbine brake and runaway. The root cause of these instability phenomena is the abnormal unsteady flow (especially the backflow) inside the pump-turbine. In the present paper, numerical simulation method is adopted to investigate the characteristics of the flow inside the whole passage of pump-turbine with two guide vane openings (6° and 21° respectively) and three kinds of operating conditions (turbine, runaway and turbine braking respectively). A quantitative analysis of backflow is performed in both the axial and radial directions and the generation and development of backflow in the pump turbine are revealed with great details.

  10. Stiffness-generated rigid-body mode shapes for Lanczos eigensolution with SUPORT DOF by way of a MSC/NASTRAN DMAP alter

    NASA Technical Reports Server (NTRS)

    Abdallah, Ayman A.; Barnett, Alan R.; Widrick, Timothy W.; Manella, Richard T.; Miller, Robert P.

    1994-01-01

    When using all MSC/NASTRAN eigensolution methods except Lanczos, the analyst can replace the coupled system rigid-body modes calculated within DMAP module READ with mass orthogonalized and normalized rigid-body modes generated from the system stiffness. This option is invoked by defining MSC/NASTRAN r-set degrees of freedom via the SUPORT bulk data card. The newly calculated modes are required if the rigid-body modes calculated by the eigensolver are not 'clean' due to numerical roundoffs in the solution. When performing transient structural dynamic load analysis, the numerical roundoffs can result in inaccurate rigid-body accelerations which affect steady-state responses. Unfortunately, when using the Lanczos method and defining r-set degrees of freedom, the rigid-body modes calculated within DMAP module REIGL are retained. To overcome this limitation and to allow MSC/NASTRAN to handle SUPORT degrees of freedom identically for all eigensolvers, a DMAP Alter has been written which replaces Lanczos-calculated rigid-body modes with stiffness-generated rigid-body modes. The newly generated rigid-body modes are normalized with respect to the system mass and orthogonalized using the Gram-Schmidt technique. This algorithm has been implemented as an enhancement to an existing coupled loads methodology.

  11. New in situ generated acylhydrazidate-coordinated complexes and acylhydrazide molecules: Synthesis, structural characterization and photoluminescence property

    NASA Astrophysics Data System (ADS)

    Wang, Yan-Ning; Huo, Qi-Sheng; Zhang, Ping; Yu, Jie-Hui; Xu, Ji-Qing

    2016-10-01

    By utilizing the hydrothermal in situ acylation of organic acids with N2H4, three acylhydrazidate-coordinated compounds [Mn(L1)2(H2O)2] (L1 = 2,3-quinolinedicarboxylhydrazidate; HL1 = 2,3-dihydropyridazino[4,5-b] quinoline-1,4-dione) 1, [Mn2(ox)(L2)2(H2O)6]·2H2O (L2 = benzimidazolate-5,6-dicarboxylhydrazide; HL2 = 6,7-dihydro-1H-imidazo[4,5-g]phthalazine-5,8-dione; ox = oxalate) 2, and [Cd(HL3)(bpy)] (L3 = 4,5-di(3‧-carboxylphenyl)phthalhydrazidate; H3L3 = 6,7-dihydro-1H-imidazo[4,5-g]phthalazine-5,8-dione; bpy = 2,2‧-bipyridine) 3, as well as two acylhydrazide molecules L4 (L4 = oxepino[2,3,4-de:7,6,5-d‧e‧]diphthalazine-4,10(5H,9H)-dione) 4 and L5 (L5 = 4,5-dibromophthalhydrazide; L5 = 6,7-dibromo-2,3-dihydrophthalazine-1,4-dione) 5 were obtained. X-ray single-crystal diffraction analysis reveals that (i) 1 only possesses a mononuclear structure, but it self-assembles into a 2-D supramolecular network via the Nhydrazinesbnd H ⋯ Nhydrazine and Owsbnd H ⋯ Ohydroxylimino interactions; (ii) 2 exhibits a dinuclear structure. Ox acts as the linker, while L2 just serves as a terminal ligand; (iii) In 3, L3 acts as a 3-connected node to propagate the 7-coordinated Cd2 + centers into a 1-D double-chain structure; (iv) 4 is a special acylhydrazide molecule. Two sbnd OH groups for the intermediates 3,3‧-biphthalhydrazide further lose one water molecule to form 4; (v) 5 is a common monoacylhydrazide molecule. Via the Nhydrazinesbnd H ⋯ Ohydrazine, Ohydroxyliminosbnd H ⋯ Oacylamino and the π ⋯ π interactions, it self-assembles into a 2-D supramolecular network. The photoluminescence analysis reveals that 4 emits light with the maxima at 510 nm.

  12. A new, model-free calculation method to determine the coordination modes and distribution of copper(II) among the metal binding sites of multihistidine peptides using circular dichroism spectroscopy.

    PubMed

    Osz, Katalin

    2008-12-01

    A new calculation method to determine microscopic protonation processes from CD spectra measured at different pH and Cu(II):ligand ratios was developed and used to give the relative binding strengths for the three histidines of hsPrP(84-114), a 31-mer polypeptide modeling the N-terminal copper(II) binding region of human (homo sapiens) prion protein. Mutants of hsPrP(84-114) with two or one histidyl residues have also been synthesized and their copper(II) complexes studied by CD spectroscopy. The 1-His models were analyzed first, and the molar CD spectra for the different coordination modes on the different histidines were calculated using the general computational program PSEQUAD. These spectra were deconvoluted into the sum of Gaussian curves and used as a first parameter set to calculate the molar spectra for the different coordination modes (3N and 4N coordination) and coordination positions (His85, His96 and His111) of the 2-His peptides. The calculation method therefore does not require the direct use of CD spectra measured in the smaller peptide models. This is a significant improvement over earlier calculation methods. In the same runs, the stepwise deprotonation pK(mic) values were refined and the pH-dependent distribution of copper(II) between the two histidines was determined. The results revealed the high, but different copper(II) binding affinities of the three separate histidines in the following order: His85 < His96His111. The calculation also showed that molar CD spectra which belong to the same coordination mode and coordination position in different ligands have very similar transition energies but different intensities. For this reason, direct transfer of molar CD spectra between different ligands may be a source of error, but the pK(mic) values and the copper(II) binding preferences are transferable from the 2-His peptides to the 3-His hsPrP(84-114).

  13. Multiwavelength generation based on a mode-locked fiber laser using carbon nanotube and fiber Fabry-Perot filter.

    PubMed

    Wang, Yuanwu; Xia, Li; Yang, Chengliang; Zhang, Yating; Li, Lecheng; Xie, Zhenghai; Fu, Songnian; Liu, Deming

    2013-09-10

    In this paper, a novel and compact configuration of stable multiwavelength generation with a uniform wavelength interval is proposed for the first time to our knowledge. It employs a mode-locked fiber laser using a carbon nanotube and spectrum-slicing technique. A flat rectangular optical output spectrum is demonstrated by adjusting the dispersion value of the fiber-loop cavity and the pump power. With a fiber Fabry-Perot filter, 33 wavelengths with 0.2 nm spacing are obtained among the power uniformity of 2.3 dB. Moreover, the variations of output power at each wavelength are all less than 0.1 dB, which implies excellent stability of the whole structure.

  14. Simulation of generation of dissipative soliton, dissipative soliton resonance and noise-like pulse in Yb-doped mode-locked fiber lasers.

    PubMed

    Cheng, Zhaochen; Li, Huihui; Wang, Pu

    2015-03-09

    we report three types of pulse generation in Yb-doped nonlinear polarization rotation mode-locked fiber lasers in all-normal-dispersion regime through simulation, including dissipative soliton, dissipative soliton resonance and noise-like pulse. We distinguish the different conditions of generating such different pulses by analyzing the transmission curve of saturable absorber, which plays a key role in pulse shaping.

  15. electronic Ligand Builder and Optimisation Workbench (eLBOW): A tool for ligand coordinate and restraint generation

    SciTech Connect

    Moriarty, Nigel; Grosse-Kunstleve, Ralf; Adams, Paul

    2009-07-01

    The electronic Ligand Builder and Optimisation Workbench (eLBOW) is a program module of the PHENIX suite of computational crystallographic software. It's designed to be a flexible procedure using simple and fast quantum chemical techniques to provide chemically accurate information for novel and known ligands alike. A variety of input formats and options allow for the attainment of a number of diverse goals including geometry optimisation and generation of restraints.

  16. Calculating Robot-Joint Coordinates From Image Coordinates

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Detailed knowledge of robot joints not required. Algorithm generates approximate mathematical models of coordinates of joints of robot as functions of coordinates of points in images of work region viewed by television cameras. Joint coordinates necessary to position and orient end effector calculated by mathematical models fitted to experimentally determined data on positions, orientations, and joint coordinates. Generates models as functions of desired location of end effector of robot. Does not require priori knowledge of kinematic equations of robot.

  17. Coordinated turn-and-reach movements. I. Anticipatory compensation for self-generated coriolis and interaction torques

    NASA Technical Reports Server (NTRS)

    Pigeon, Pascale; Bortolami, Simone B.; DiZio, Paul; Lackner, James R.

    2003-01-01

    When reaching movements involve simultaneous trunk rotation, additional interaction torques are generated on the arm that are absent when the trunk is stable. To explore whether the CNS compensates for such self-generated interaction torques, we recorded hand trajectories in reaching tasks involving various amplitudes and velocities of arm extension and trunk rotation. Subjects pointed to three targets on a surface slightly above waist level. Two of the target locations were chosen so that a similar arm configuration relative to the trunk would be required for reaching to them, one of these targets requiring substantial trunk rotation, the other very little. Significant trunk rotation was necessary to reach the third target, but the arm's radial distance to the body remained virtually unchanged. Subjects reached at two speeds-a natural pace (slow) and rapidly (fast)-under normal lighting and in total darkness. Trunk angular velocity and finger velocity relative to the trunk were higher in the fast conditions but were not affected by the presence or absence of vision. Peak trunk velocity increased with increasing trunk rotation up to a maximum of 200 degrees /s. In slow movements, peak finger velocity relative to the trunk was smaller when trunk rotation was necessary to reach the targets. In fast movements, peak finger velocity was approximately 1.7 m/s for all targets. Finger trajectories were more curved when reaching movements involved substantial trunk rotation; however, the terminal errors and the maximal deviation of the trajectory from a straight line were comparable in slow and fast movements. This pattern indicates that the larger Coriolis, centripetal, and inertial interaction torques generated during rapid reaches were compensated by additional joint torques. Trajectory characteristics did not vary with the presence or absence of vision, indicating that visual feedback was unnecessary for anticipatory compensations. In all reaches involving trunk

  18. Coordinated turn-and-reach movements. I. Anticipatory compensation for self-generated coriolis and interaction torques.

    PubMed

    Pigeon, Pascale; Bortolami, Simone B; DiZio, Paul; Lackner, James R

    2003-01-01

    When reaching movements involve simultaneous trunk rotation, additional interaction torques are generated on the arm that are absent when the trunk is stable. To explore whether the CNS compensates for such self-generated interaction torques, we recorded hand trajectories in reaching tasks involving various amplitudes and velocities of arm extension and trunk rotation. Subjects pointed to three targets on a surface slightly above waist level. Two of the target locations were chosen so that a similar arm configuration relative to the trunk would be required for reaching to them, one of these targets requiring substantial trunk rotation, the other very little. Significant trunk rotation was necessary to reach the third target, but the arm's radial distance to the body remained virtually unchanged. Subjects reached at two speeds-a natural pace (slow) and rapidly (fast)-under normal lighting and in total darkness. Trunk angular velocity and finger velocity relative to the trunk were higher in the fast conditions but were not affected by the presence or absence of vision. Peak trunk velocity increased with increasing trunk rotation up to a maximum of 200 degrees /s. In slow movements, peak finger velocity relative to the trunk was smaller when trunk rotation was necessary to reach the targets. In fast movements, peak finger velocity was approximately 1.7 m/s for all targets. Finger trajectories were more curved when reaching movements involved substantial trunk rotation; however, the terminal errors and the maximal deviation of the trajectory from a straight line were comparable in slow and fast movements. This pattern indicates that the larger Coriolis, centripetal, and inertial interaction torques generated during rapid reaches were compensated by additional joint torques. Trajectory characteristics did not vary with the presence or absence of vision, indicating that visual feedback was unnecessary for anticipatory compensations. In all reaches involving trunk

  19. Enhanced second-harmonic generation from metal-integrated semiconductor nanowires via highly confined whispering gallery modes.

    PubMed

    Ren, Ming-Liang; Liu, Wenjing; Aspetti, Carlos O; Sun, Liaoxin; Agarwal, Ritesh

    2014-11-12

    Coherent and tunable nanoscale light sources utilizing optical nonlinearities are required for applications ranging from imaging and bio-sensing to on-chip all-optical signal processing. However, owing to their small sizes, the efficiency of nanostructures even with high nonlinear coefficients is poor, therefore requiring very high excitation energies. Although surface-plasmon resonances of metal nanostructures can enhance surface nonlinear processes such as second-harmonic generation, they still suffer from low conversion efficiencies owing to their intrinsically low nonlinear coefficients. Here we show highly enhanced and directional second-harmonic generation from individual CdS nanowires integrated with silver nanocavities (>1,000 times higher external efficiency compared with bare CdS), in which the lowest-order whispering gallery mode is engineered to concentrate light in the nonlinear material while minimizing Ohmic losses. The directional nonlinear signal is redirected into another waveguide, which is then utilized to configure an optical router that can potentially serve as a tunable coherent light source to enable on-chip signal processing for integrated nanophotonic systems.

  20. Driven evolution of a constitutional dynamic library of molecular helices toward the selective generation of [2 x 2] gridlike arrays under the pressure of metal ion coordination.

    PubMed

    Giuseppone, Nicolas; Schmitt, Jean-Louis; Lehn, Jean-Marie

    2006-12-27

    Constitutional dynamics, self-assembly, and helical-folding control are brought together in the efficient Sc(OTf)3/microwave-catalyzed transimination of helical oligohydrazone strands, yielding highly diverse dynamic libraries of interconverting constituents through assembly, dissociation, and exchange of components. The transimination-type mechanism of the ScIII-promoted exchange, as well as its regioselectivity, occurring only at the extremities of the helical strands, allow one to perform directional terminal polymerization/depolymerization processes when starting with dissymmetric strands. A particular library is subsequently brought to express quantitatively [2 x 2] gridlike metallosupramolecular arrays in the presence of ZnII ions by component recombination generating the correct ligand from the dynamic set of interconverting strands. This behavior represents a process of driven evolution of a constitutional dynamic chemical system under the pressure (coordination interaction) of an external effector (metal ions).

  1. Syntheses and structures of two new coordination polymers generated from a 4-aminotriazole-bridged organic ligand and Co(II) salts.

    PubMed

    Wang, Xue Ru; Ma, Jian Ping; Dong, Yu Bin

    2017-03-01

    Organic ligands and counter-anions influence the coordination spheres of metal cations and hence the construction of coordination polymers (CPs). The specific bent geometries of five-membered heterocyclic triazole bridging organic ligands are capable of generating CPs with novel patterns not easily obtained using rigid linear ligands. A multidentate 4-aminotriazole-bridged organic ligand, namely 4-amino-3,5-bis(4,3'-bipyridyl-5'-yl)-4H-1,2,4-triazole (L) has been prepared and used to synthesize two Co(II) coordination polymers, namely poly[[[μ2-4-amino-3,5-bis(4,3'-bipyridyl-5'-yl)-4H-1,2,4-triazole-κ(2)N:N']bis(methanol-κO)cobalt(II)] bis(perchlorate)], {[Co(C22H16N8)2(CH3OH)2](ClO4)2}n, (I), and poly[[μ3-4-amino-3,5-bis(4,3'-bipyridyl-5'-yl)-4H-1,2,4-triazole-κ(3)N:N':N'']dichloridocobalt(II)], [CoCl2(C22H16N8)]n, (II), using CoX2 salts [X = ClO4 for (I) and Cl for (II)] under solvothermal conditions. Single-crystal X-ray structure analysis revealed that they both feature two-dimensional networks. Cobalt is located on an inversion centre in (I) and in a general position in (II). In (I), L functions as a bidentate cis-conformation ligand linking Co(II) ions, while it functions as a tridentate trans-conformation linker binding Co(II) ions in (II). In addition, O-H...N and N-H...O hydrogen bonds and C-H...π interactions exist in (I), while N-H...Cl and π-π interactions exist in (II), and these weak interactions play an important role in aligning the two-dimensional nets of (I) and (II) in the solid state. As the compounds were synthesized under the same conditions, the significant structural variations between (I) and (II) are believed to be determined by the different sizes and coordination abilities of the counter-anions. IR spectroscopy and diffuse reflectance UV-Vis spectra were also used to investigate the title compounds.

  2. Different pulse pattern generation by frequency detuning in pulse modulated actively mode-locked ytterbium doped fiber laser

    NASA Astrophysics Data System (ADS)

    Chen, He; Chen, Sheng-Ping; Si, Lei; Zhang, Bin; Jiang, Zong-Fu

    2015-10-01

    We report the results of our recent experimental investigation of the modulation frequency detuning effect on the output pulse dynamics in a pulse modulated actively mode-locked ytterbium doped fiber laser. The experimental study shows the existence of five different mode-locking states that mainly depend on the modulation frequency detuning, which are: (a) amplitude-even harmonic/fundamental mode-locking, (b) Q-switched harmonic/fundamental mode-locking, (c) sinusoidal wave modulation mode, (d) pulses bundle state, and (e) noise-like state. A detailed experimental characterization of the output pulses dynamics in each operating mode is presented.

  3. 10 GHz, 1.1 ps optical pulse generation from a regeneratively mode-locked Yb fiber laser in the 1.1 μm band.

    PubMed

    Koizumi, Kengo; Yoshida, Masato; Hirooka, Toshihiko; Nakazawa, Masataka

    2011-12-05

    We report a 10 GHz harmonically and regeneratively mode-locked Yb fiber laser with a phase-locked loop (PLL) technique at 1.1 μm. Stable mode locking was achieved by optimizing the average dispersion of the fiber cavity to an anomalous dispersion to operate as a soliton laser. As a result, a 1.1 ps optical pulse with a timing jitter of 140 fs was successfully generated.

  4. Sodium D2 resonance radiation in single-pass sum-frequency generation with actively mode-locked Nd:YAG lasers

    NASA Astrophysics Data System (ADS)

    Saito, Norihito; Akagawa, Kazuyuki; Ito, Mayumi; Takazawa, Akira; Hayano, Yutaka; Saito, Yoshihiko; Ito, Meguru; Takami, Hideki; Iye, Masanori; Wada, Satoshi

    2007-07-01

    We report on a sodium D2 resonance coherent light source achieved in single-pass sum-frequency generation in periodically poled MgO-doped stoichiometric lithium tantalate with actively mode-locked Nd:YAG lasers. Mode-locked pulses at 1064 and 1319 nm are synchronized with a time resolution of 37 ps with the phase adjustment of the radio frequencies fed to acousto-optic mode lockers. An output power of 4.6 W at 589.1586 nm is obtained, and beam quality near the diffraction limit is also achieved in a simple design.

  5. Sodium D2 resonance radiation in single-pass sum-frequency generation with actively mode-locked Nd:YAG lasers.

    PubMed

    Saito, Norihito; Akagawa, Kazuyuki; Ito, Mayumi; Takazawa, Akira; Hayano, Yutaka; Saito, Yoshihiko; Ito, Meguru; Takami, Hideki; Iye, Masanori; Wada, Satoshi

    2007-07-15

    We report on a sodium D(2) resonance coherent light source achieved in single-pass sum-frequency generation in periodically poled MgO-doped stoichiometric lithium tantalate with actively mode-locked Nd:YAG lasers. Mode-locked pulses at 1064 and 1319 nm are synchronized with a time resolution of 37 ps with the phase adjustment of the radio frequencies fed to acousto-optic mode lockers. An output power of 4.6 W at 589.1586 nm is obtained, and beam quality near the diffraction limit is also achieved in a simple design.

  6. General curvilinear coordinate systems

    NASA Technical Reports Server (NTRS)

    Thompson, J. P.

    1982-01-01

    The basic ideas of the construction and use of numerically-generated boundary-fitted coordinate systems for the numerical solution of partial differential equations are discussed. With such coordinate systems, all computation can be done on a fixed square grid in the rectangular transformed region regardless of the shape or movement of the physical boundaries. A number of different types of configurations for the transformed region and the basic transformation relations from a cartesian system to a general curvilinear system are given. The material of this paper is applicable to all types of coordinate system generation.

  7. On the dispersion management of fluorite whispering-gallery mode resonators for Kerr optical frequency comb generation in the telecom and mid-infrared range.

    PubMed

    Lin, Guoping; Chembo, Yanne K

    2015-01-26

    Optical whispering gallery mode (WGM) resonators have been very attracting platforms for versatile Kerr frequency comb generations. We report a systematic study on the material dispersion of various optical materials that are capable of supporting quality factors above 109. Using an analytical approximation of WGM resonant frequencies in disk resonators, we investigate the effect of the geometry and transverse mode order on the total group-velocity dispersion (GVD). We demonstrate that the major radii and the radial mode indices play an important role in tailoring the GVD of WGM resonators. In particular, our study shows that in WGM disk-resonators, the polar families of modes have very similar GVD, while the radial families of modes feature dispersion values that can differ by up to several orders of magnitude. The effect of these giant dispersion shifts are experimentally evidenced in Kerr comb generation with magnesium fluoride. From a more general perspective, this critical feature enables to push the zero-dispersion wavelength of fluorite crystals towards the mid-infrared (mid-IR) range, thereby allowing for efficient Kerr comb generation in that spectral range. We show that barium fluoride is the most interesting crystal in this regard, due to its zero dispersion wavelength (ZDW) at 1.93 μm and an optimal dispersion profile in the mid-IR regime. We expect our results to facilitate the design of different platforms for Kerr frequency comb generations in both telecommunication and mid-IR spectral ranges.

  8. A new coordination mode of (E)-3-(3-hydroxyl-phenyl)-acrylic acid in copper complex: Crystal structure and magnetic properties

    SciTech Connect

    Jin, Xin; Zhou, Pei; Zheng, Chunying; Li, Hui

    2015-05-15

    A copper complex ([Cu(py){sub 2}(L){sub 2}]·2CH{sub 3}OH){sub n} (HL=(E)-3-(3-hydroxyl-phenyl)-acrylic acid) (1) with acrylic acid ligand was synthesized and structurally analyzed by IR, elemental analysis, TGA and the single-crystal X-ray diffraction methods. It is the first time to find that phenolic hydroxyl of L coordinates to Cu(II). Complex 1 exhibits 1D chain by a double-bridge of ligands, and the 3D supramolecular framework in complex 1 is constructed by π–π stacking interactions and van der Waals Contacts among the 1D chains. The magnetic properties of complex 1 have been studied. - Graphical abstract: A copper complex based on (E)-3-(3-hydroxyl-phenyl)-acrylic acid in a novel coordinated way was synthesized and a ferromagnetic exchange interactions between neighboring Cu(II) ions has be achieved. - Highlights: • A new copper complex with acrylic acid ligand was synthesized and analyzed. • We find the phenolic hydroxyl of MCA ligand coordinates to metal ion firstly. • A ferromagnetic exchange interactions between Cu(II) ions has been achieved.

  9. Two-Dimensional Au-Nanoprism/Reduced Graphene Oxide/Pt-Nanoframe as Plasmonic Photocatalysts with Multiplasmon Modes Boosting Hot Electron Transfer for Hydrogen Generation.

    PubMed

    Lou, Zaizhu; Fujitsuka, Mamoru; Majima, Tetsuro

    2017-02-16

    Two-dimensional Au-nanoprism/reduced graphene oxide (rGO)/Pt-nanoframe was synthesized as plasmonic photocatalyt, exhibiting activity of photocatalytic hydrogen generation greater than those of Au-nanorod/rGO/Pt-nanoframe and metallic plasmonic photocatalyst Pt-Au. The single-particle plasmonic photoluminescence study demonstrated that Au-nanorod has only a longitudinal plasmon resonance mode for hot electron transfer to rGO, while Au-nanoprism has in-plane dipole and multipole surface plasmon resonance modes for hot electron transfer, leading to highly efficient charge separation for hydrogen generation.

  10. Hybrid Wing Body Shielding Studies Using an Ultrasonic Configurable Fan Artificial Noise Source Generating Typical Turbofan Modes

    NASA Technical Reports Server (NTRS)

    Sutliff, Daniel L.; Brown, Cliff; Walker, Bruce E.

    2014-01-01

    An Ultrasonic Configurable Fan Artificial Noise Source (UCFANS) was designed, built, and tested in support of the NASA Langley Research Center's 14x22 wind tunnel test of the Hybrid Wing Body (HWB) full 3-D 5.8% scale model. The UCFANS is a 5.8% rapid prototype scale model of a high-bypass turbofan engine that can generate the tonal signature of proposed engines using artificial sources (no flow). The purpose of the test was to provide an estimate of the acoustic shielding benefits possible from mounting the engine on the upper surface of an HWB aircraft using the projected signature of the engine currently proposed for the HWB. The modal structures at the rating points were generated from inlet and exhaust nacelle configurations - a flat plate model was used as the shielding surface and vertical control surfaces with correct plan form shapes were also tested to determine their additional impact on shielding. Radiated acoustic data were acquired from a traversing linear array of 13 microphones, spanning 36 inches. Two planes perpendicular, and two planes parallel, to the axis of the nacelle were acquired from the array sweep. In each plane the linear array traversed 4 sweeps, for a total span of 168 inches acquired. The resolution of the sweep is variable, so that points closer to the model are taken at a higher resolution. Contour plots of Sound Pressure Levels, and integrated Power Levels, from nacelle alone and shielded configurations are presented in this paper; as well as the in-duct mode power levels.

  11. Hybrid Wing Body Shielding Studies Using an Ultrasonic Configurable Fan Artificial Noise Source Generating Typical Turbofan Modes

    NASA Technical Reports Server (NTRS)

    Sutliff, Daniel l.; Brown, Clifford A.; Walker, Bruce E.

    2014-01-01

    An Ultrasonic Configurable Fan Artificial Noise Source (UCFANS) was designed, built, and tested in support of the NASA Langley Research Center's 14- by 22-ft wind tunnel test of the Hybrid Wing Body (HWB) full 3-D 5.8 percent scale model. The UCFANS is a 5.8 percent rapid prototype scale model of a high-bypass turbofan engine that can generate the tonal signature of proposed engines using artificial sources (no flow). The purpose of the test was to provide an estimate of the acoustic shielding benefits possible from mounting the engine on the upper surface of an HWB aircraft using the projected signature of the engine currently proposed for the HWB. The modal structures at the rating points were generated from inlet and exhaust nacelle configurations--a flat plate model was used as the shielding surface and vertical control surfaces with correct plan form shapes were also tested to determine their additional impact on shielding. Radiated acoustic data were acquired from a traversing linear array of 13 microphones, spanning 36 in. Two planes perpendicular, and two planes parallel, to the axis of the nacelle were acquired from the array sweep. In each plane the linear array traversed four sweeps, for a total span of 168 in. acquired. The resolution of the sweep is variable, so that points closer to the model are taken at a higher resolution. Contour plots of Sound Pressure Levels, and integrated Power Levels, from nacelle alone and shielded configurations are presented in this paper; as well as the in-duct mode power levels

  12. An improved generator coordinate Hartree-Fock method applied to the choice of contracted Gaussian basis sets for first-row diatomic molecules

    SciTech Connect

    Pinheiro, J.C.; Jorge, F.E.; Castro, E.V.R. de

    2000-05-15

    Accurate Gaussian basis sets (18s for Li and Be and 20s11p for the atoms from B to Ne) for the first-row atoms, generated with an improved generator coordinate Hartree-Fock method, were contracted and enriched with polarization functions. These basis sets were tested for B{sub 2}, C{sub 2}, BeO, Cn{sup {minus}}, LiF, N{sub 2}, CO, BF, NO{sup +}, O{sub 2}, and F{sub 2}. At the Hartree-Fock (HP), second-order Moeller-Plesset (MP2), fourth-order Moeller-Plesset (MP4), and density functional theory (DFT) levels, the dipole moments, bond lengths, and harmonic vibrational frequencies were studied, and at the MP2, MP4, and DFT levels, the dissociation energies were evaluated and compared with the corresponding experimental values and with values obtained using other contracted Gaussian basis sets and numerical HF calculations. For all diatomic molecules studied, the differences between the total energies, obtained with the largest contracted basis set [6s5p3d1f], and those calculated with the numerical HF methods were always less than 3.2 mhartree.

  13. Radical-generating coordination complexes as tools for rapid and effective fragmentation and fluorescent labeling of nucleic acids for microchip hybridization.

    SciTech Connect

    Kelly, J. J.; Chernov, B. K.; Tovstanovsky, I.; Mirzabekov, A. D.; Bavykin, S. G.; Biochip Technology Center; Northwestern Univ.; Engelhardt Inst. of Molecular Biology

    2002-12-15

    DNA microchip technology is a rapid, high-throughput method for nucleic acid hybridization reactions. This technology requires random fragmentation and fluorescent labeling of target nucleic acids prior to hybridization. Radical-generating coordination complexes, such as 1,10-phenanthroline-Cu(II) (OP-Cu) and Fe(II)-EDTA (Fe-EDTA), have been commonly used as sequence nonspecific 'chemical nucleases' to introduce single-strand breaks in nucleic acids. Here we describe a new method based on these radical-generating complexes for random fragmentation and labeling of both single- and double-stranded forms of RNA and DNA. Nucleic acids labeled with the OP-Cu and the Fe-EDTA protocols revealed high hybridization specificity in hybridization with DNA microchips containing oligonucleotide probes selected for identification of 16S rRNA sequences of the Bacillus group microorganisms.We also demonstrated cDNA- and cRNA-labeling and fragmentation with this method. Both the OP-Cu and Fe-EDTA fragmentation and labeling procedures are quick and inexpensive compared to other commonly used methods. A column-based version of the described method does not require centrifugation and therefore is promising for the automation of sample preparations in DNA microchip technology as well as in other nucleic acid hybridization studies.

  14. Intermediate vibrational coordinate localization with harmonic coupling constraints

    NASA Astrophysics Data System (ADS)

    Hanson-Heine, Magnus W. D.

    2016-05-01

    Optimized normal coordinates can significantly improve the speed and accuracy of vibrational frequency calculations. However, over-localization can occur when using unconstrained spatial localization techniques. The unintuitive mixtures of stretching and bending coordinates that result can make interpreting spectra more difficult and also cause artificial increases in mode-coupling during anharmonic calculations. Combining spatial localization with a constraint on the coupling between modes can be used to generate coordinates with properties in-between the normal and fully localized schemes. These modes preserve the diagonal nature of the mass-weighted Hessian matrix to within a specified tolerance and are found to prevent contamination between the stretching and bending vibrations of the molecules studied without a priori classification of the different types of vibration present. Relaxing the constraint can also be used to identify which normal modes form specific groups of localized modes. The new coordinates are found to center on more spatially delocalized functional groups than their fully localized counterparts and can be used to tune the degree of vibrational correlation energy during anharmonic calculations.

  15. Shielding Characteristics Using an Ultrasonic Configurable Fan Artificial Noise Source to Generate Modes - Experimental Measurements and Analytical Predictions

    NASA Technical Reports Server (NTRS)

    Sutliff, Daniel L.; Walker, Bruce E.

    2014-01-01

    An Ultrasonic Configurable Fan Artificial Noise Source (UCFANS) was designed, built, and tested in support of the NASA Langley Research Center's 14x22 wind tunnel test of the Hybrid Wing Body (HWB) full 3-D 5.8% scale model. The UCFANS is a 5.8% rapid prototype scale model of a high-bypass turbofan engine that can generate the tonal signature of proposed engines using artificial sources (no flow). The purpose of the program was to provide an estimate of the acoustic shielding benefits possible from mounting an engine on the upper surface of a wing; a flat plate model was used as the shielding surface. Simple analytical simulations were used to preview the radiation patterns - Fresnel knife-edge diffraction was coupled with a dense phased array of point sources to compute shielded and unshielded sound pressure distributions for potential test geometries and excitation modes. Contour plots of sound pressure levels, and integrated power levels, from nacelle alone and shielded configurations for both the experimental measurements and the analytical predictions are presented in this paper.

  16. Design and analysis of single-mode tellurite photonic crystal fibers for stimulated Brillouin scattering based slow-light generation.

    PubMed

    Jain, Varsha; Sharma, Shubham; Saini, Than Singh; Kumar, Ajeet; Sinha, Ravindra Kumar

    2016-09-01

    We theoretically examine two designs of single-mode (i) Er-doped tellurite and (ii) undoped tellurite photonic crystal fiber (PCF) for generation of slow light with tunable features based on stimulated Brillouin scattering. We obtained (i) Brillouin gain up to 91 dB and time delay of ∼145  ns at maximum allowable pump power of ∼775  mW in a 2 m Er-doped tellurite PCF and (ii) Brillouin gain up to ∼88  dB and time delay of ∼154  ns at maximum allowable pump power ∼21  mW in a 100 m undoped tellurite photonic crystal fiber. Simulated results clearly indicate that the doped tellurite PCF with Er enhances the maximum allowable pump power and comparable time delay can be obtained even with reduced photonic crystal fiber length. We believe that the carried out examination and simulation have potential impact on design and development of slow-light-based photonic devices applicable in telecommunication systems, enhancement of optical forces, and quantum computing.

  17. Generation of multiple spectral bands in a diode-pumped self-mode-locked Nd:YAP laser

    NASA Astrophysics Data System (ADS)

    Huang, Y. J.; Tzeng, Y. S.; Cho, H. H.; Chen, Y. F.; Chen, W. D.; Zhang, G.; Chen, T. C.

    2016-02-01

    A single- and multispectral-band diode end-pumped self-mode-locked Nd:YAP laser is originally demonstrated with an intracavity etalon to properly control the gain-to-loss ratios among the intermanifold lines on the 4F3/2  →  4I11/2 transition level. With a pulse repetition rate of 5.07 GHz, the shortest pulse durations under the single-spectral-band operation are achieved to be 11.1 ps at 1073 nm, 10.9 ps at 1080 nm, and 15.1 ps at 1084 nm, respectively. Moreover, the temporal overlapping of the multispectral-band pulses is experimentally found to lead to the generation of an intensity fringe pattern in the autocorrelation trace with the optical-beat frequency reaching several terahertz. A simple mathematical model is developed to elucidate the formation of a train of optical-beat pulses.

  18. Tuning vibrational mode localization with frequency windowing

    NASA Astrophysics Data System (ADS)

    Cheng, Xiaolu; Talbot, Justin J.; Steele, Ryan P.

    2016-09-01

    Local-mode coordinates have previously been shown to be an effective starting point for anharmonic vibrational spectroscopy calculations. This general approach borrows techniques from localized-orbital machinery in electronic structure theory and generates a new set of spatially localized vibrational modes. These modes exhibit a well-behaved spatial decay of anharmonic mode couplings, which, in turn, allows for a systematic, a priori truncation of couplings and increased computational efficiency. Fully localized modes, however, have been found to lead to unintuitive mixtures of characteristic motions, such as stretches and bends, and accordingly large bilinear couplings. In this work, a very simple, tunable localization frequency window is introduced, in order to realize the transition from normal modes to fully localized modes. Partial localization can be achieved by localizing only pairs of modes within this traveling frequency window, which allows for intuitive interpretation of modes. The optimal window size is suggested to be a few hundreds of wave numbers, based on small- to medium-sized test systems, including water clusters and polypeptides. The new sets of partially localized coordinates retain their spatial coupling decay behavior while providing a reduced number of potential energy evaluations for convergence of anharmonic spectra.

  19. Generation of sub-7-cycle optical pulses from a mode-locked ytterbium-doped single-mode fiber oscillator pumped by polarization-combined 915 nm laser diodes.

    PubMed

    Kurita, Takashi; Yoshida, Hidetsugu; Kawashima, Toshiyuki; Miyanaga, Noriaki

    2012-10-01

    We report on a passively mode-locked ytterbium-doped fiber oscillator pumped by polarization-combined diodes emitting at a wavelength of 915 nm instead of 976 nm. Stable mode-locked operation based on nonlinear polarization evolution generated a broad spectrum of 140 nm, spanning from 950 to 1090 nm. The output power was 16.3 mW at a repetition rate of 93.1 MHz. External compression using a pair of transmission gratings resulted in pulse durations as short as 21.6 fs, which is equivalent to 6.6 cycle optical pulses at a wavelength of around 1000 nm.

  20. Generation of 13-fs pulses from a mode-locked Ti:Al2O3 laser with reduced third-order dispersion

    NASA Astrophysics Data System (ADS)

    Proctor, Bob; Wise, Frank

    1993-02-01

    The third-order dispersion of a mode-locked Ti:Al2O3 laser has been reduced by replacing a pair of flint glass prisms with a sequence of four quartz prisms. This allows transform-limited 13-fs pulses to be generated with a gain crystal 20 mm long. To date, these are the shortest pulses generated directly from a laser.

  1. Coordination and modulation of locomotion pattern generators in Drosophila larvae: effects of altered biogenic amine levels by the tyramine beta hydroxlyase mutation.

    PubMed

    Fox, Lyle E; Soll, David R; Wu, Chun-Fang

    2006-02-01

    Forward locomotion of Drosophila melanogaster larvae is composed of rhythmic waves of contractions that are thought to be produced by segmentally organized central pattern generators. We present a systematic description of spike activity patterns during locomotive contraction waves in semi-intact wild-type and mutant larval preparations. We have shown previously that Tbetah(nM18) mutants, with altered levels of octopamine and tyramine, have a locomotion deficit. By recording en passant from the segmental nerves, we investigated the coordination of the neuronal activity driving contraction waves of the abdominal body-wall muscles. Rhythmic bursts of activity that occurred concurrently with locomotive waves were frequently observed in wild-type larvae but were rarely seen in Tbetah(nM18) mutants. These centrally generated patterned activities were eliminated in the distal stumps of both wild-type and Tbetah(nM18) larvae after severing the segmental nerve from the CNS. Patterned activities persisted in the proximal stumps deprived of sensory feedback from the periphery. Simultaneous recordings demonstrated a delay in the bursting activity between different segments, with greater delay for segments that were farther apart. In contrast, bilateral recordings within a single segment revealed a well synchronized activity pattern in nerves innervating each hemisegment in both wild-type and Tbetah(nM18) larvae. Significantly, rhythmic patterns of bursts and waves could be evoked in Tbetah(nM18) mutants by head or tail stimulation despite their highly irregular spontaneous activities. These observations suggest a role of the biogenic amines in the initiation and modulation of motor pattern generation. The technique presented here can be readily extended to examine the locomotion motor program of other mutants.

  2. Two coordination modes of CuII in a binuclear complex with N-(pyridin-2-yl­carbon­yl)pyridine-2-carboxamidate ligands

    PubMed Central

    Campos-Gaxiola, José J.; Morales-Morales, David; Höpfl, Herbert; Parra-Hake, Miguel; Reyes-Martínez, Reyna

    2012-01-01

    In the title dinuclear complex, (acetonitrile-1κN)[μ-N-(pyri­din-2-ylcarbonyl)pyridine-2-carboxamidato-1:2κ5 N,N′,N′′:O,O′][N-(pyridin-2-ylcarbonyl)pyridine-2-carboxamidato-2κ3 N,N′,N′′]bis(trifluoromethanesulfonato-1κO)dicopper(II), [Cu2(C12H8N3O2)2(CF3O3S)2(CH3CN)], one of the CuII ions is five-coordinated in a distorted square-pyramidal N3O2 environment provided by two N-(pyridin-2-ylcarbon­yl)pyridine-2-carboxamidate (bpca) ligands, while the second CuII ion is six-coordinated in a distorted octa­hedral N4O2 environment provided by one bpca ligand, two trifluoro­methansulfonate ligands and one acetonitrile mol­ecule. Weak inter­molecular C—H⋯O and C—H⋯F hydrogen bonds and π–π stacking inter­actions with centroid–centroid distances of 3.6799 (15) and 3.8520 (16) Å stabilize the crystal packing and lead to a three-dimensional network. PMID:23125602

  3. Two coordination modes of Cu(II) in a binuclear complex with N-(pyridin-2-yl-carbon-yl)pyridine-2-carboxamidate ligands.

    PubMed

    Campos-Gaxiola, José J; Morales-Morales, David; Höpfl, Herbert; Parra-Hake, Miguel; Reyes-Martínez, Reyna

    2012-10-01

    In the title dinuclear complex, (acetonitrile-1κN)[μ-N-(pyri-din-2-ylcarbonyl)pyridine-2-carboxamidato-1:2κ(5)N,N',N'':O,O'][N-(pyridin-2-ylcarbonyl)pyridine-2-carboxamidato-2κ(3)N,N',N'']bis(trifluoromethanesulfonato-1κO)dicopper(II), [Cu(2)(C(12)H(8)N(3)O(2))(2)(CF(3)O(3)S)(2)(CH(3)CN)], one of the Cu(II) ions is five-coordinated in a distorted square-pyramidal N(3)O(2) environment provided by two N-(pyridin-2-ylcarbon-yl)pyridine-2-carboxamidate (bpca) ligands, while the second Cu(II) ion is six-coordinated in a distorted octa-hedral N(4)O(2) environment provided by one bpca ligand, two trifluoro-methansulfonate ligands and one acetonitrile mol-ecule. Weak inter-molecular C-H⋯O and C-H⋯F hydrogen bonds and π-π stacking inter-actions with centroid-centroid distances of 3.6799 (15) and 3.8520 (16) Å stabilize the crystal packing and lead to a three-dimensional network.

  4. Generation of 30  fs pulses from a diode-pumped graphene mode-locked Yb:CaYAlO4 laser.

    PubMed

    Ma, Jie; Huang, Haitao; Ning, Kaijie; Xu, Xiaodong; Xie, Guoqiang; Qian, Liejia; Loh, Kian Ping; Tang, Dingyuan

    2016-03-01

    Stable 30 fs pulses centered at 1068 nm (less than 10 optical cycles) are demonstrated in a diode pumped Yb:CaYAlO4 laser by using high-quality chemical vapor deposited monolayer graphene as the saturable absorber. The mode-locked 8.43 optical-cycle pulses have a spectral bandwidth of ∼50  nm and a pulse repetition frequency of ∼113.5  MHz. To the best of our knowledge, this is the shortest pulse ever reported for graphene mode-locked lasers and mode-locked Yb-doped bulk lasers. Our experimental results demonstrate that graphene mode locking is a very promising practical technique for directly generating few-cycle optical pulses from a laser oscillator.

  5. Generation of 30 fs pulses from a diode-pumped graphene mode-locked Yb:CaYAlO_4 laser

    NASA Astrophysics Data System (ADS)

    Ma, Jie; Huang, Haitao; Ning, Kaijie; Xu, Xiaodong; Xie, Guoqiang; Qian, Liejia; Loh, Kian Ping; Tang, Dingyuan

    2016-03-01

    Stable 30 fs pulses centered at 1068 nm (less than 10 optical cycles) are demonstrated in a diode pumped Yb:CaYAlO4 laser by using high-quality chemical vapor deposited monolayer graphene as the saturable absorber. The mode locked 8.43 optical-cycle pulses have a spectral bandwidth of ~ 50 nm and a pulse repetition frequency of ~ 113.5 MHz. To our knowledge, this is the shortest pulse ever reported for graphene mode-locked lasers and mode-locked Yb-doped bulk lasers. Our experimental results demonstrate that graphene mode locking is a very promising practical technique to generate few-cycle optical pulses directly from a laser oscillator.

  6. Synchronization of 1064 and 1319 nm Pulses Emitted from Actively Mode-Locked Nd:YAG Lasers and Its Application to 589 nm Sum-Frequency Generation

    NASA Astrophysics Data System (ADS)

    Saito, Norihito; Akagawa, Kazuyuki; Hayano, Yutaka; Saito, Yoshihiko; Takami, Hideki; Iye, Masanori; Wada, Satoshi

    2005-11-01

    Sum-frequency generation was carried out by mixing 1064 and 1319 nm pulses emitted from actively mode-locked neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers for efficient 589 nm light generation. A radio frequency of approximately 75 MHz was split into two and fed to acousto-optic mode lockers of two lasers for mode-locked operation. The synchronization of the pulses was achieved by controlling the phase difference between the radio frequencies. The maximum output power at 589 nm reached 260 mW, which corresponded to an energy conversion efficiency of more than 13%. The output power was 3.8-fold that in continuous-wave operation.

  7. Optical parametric generation by a simultaneously Q-switched mode-locked single-oscillator thulium-doped fiber laser in orientation-patterned gallium arsenide.

    PubMed

    Donelan, Brenda; Kneis, Christian; Scurria, Giuseppe; Cadier, Benoît; Robin, Thierry; Lallier, Eric; Grisard, Arnaud; Gérard, Bruno; Eichhorn, Marc; Kieleck, Christelle

    2016-11-01

    Optical parametric generation is demonstrated in orientation-patterned gallium arsenide, pumped by a novel single-oscillator simultaneously Q-switched and mode-locked thulium-doped fiber laser, downconverting the pump radiation into the mid-infrared wavelength regime. The maximum output energy reached is greater than 2.0 μJ per pump pulse.

  8. A Further Comparison of Manual Signing, Picture Exchange, and Speech-Generating Devices as Communication Modes for Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    van der Meer, Larah; Sutherland, Dean; O'Reilly, Mark F.; Lancioni, Giulio E.; Sigafoos, Jeff

    2012-01-01

    We compared acquisition of, and preference for, manual signing (MS), picture exchange (PE), and speech-generating devices (SGDs) in four children with autism spectrum disorders (ASD). Intervention was introduced across participants in a non-concurrent multiple-baseline design and acquisition of the three communication modes was compared in an…

  9. Transform-limited pulse generation in normal cavity dispersion erbium doped single-walled carbon nanotubes mode-locked fiber ring laser.

    PubMed

    Chernysheva, M A; Krylov, A A; Ogleznev, A A; Arutyunyan, N R; Pozharov, A S; Obraztsova, E D; Dianov, E M

    2012-10-08

    We demonstrate an erbium doped fiber ring laser mode-locked with a carboxymetylcellulose high-optical quality film with dispersed single-walled carbon nanotubes (SWCNT). The laser with large normal net cavity dispersion generates near bandwidth-limited picosecond inverse modified soliton pulses at 1.56 µm.

  10. Titanium Dioxide (TiO2) film as a new saturable absorber for generating mode-locked Thulium-Holmium doped all-fiber laser

    NASA Astrophysics Data System (ADS)

    Mohd Rusdi, Muhammad Farid; Latiff, Anas Abdul; Paul, Mukul Chandra; Das, Shyamal; Dhar, Anirban; Ahmad, Harith; Harun, Sulaiman Wadi

    2017-03-01

    We report the generation of mode-locked thulium-holmium doped fiber laser (THDFL) at 1979 nm. This is a first demonstration of mode-locked by using Titanium Dioxide (TiO2) film as a saturable absorber (SA). A piece of 1 mm×1 mm TiO2 film was sandwiched in between two fiber ferrule in the cavity. Fabrication process of TiO2 film incorporated a TiO2 and a polyvinyl alcohol (PVA). The stable 9 MHz repetition rate of mode-locked mode operation with 58 dB SNR was generated under pump power of 902-1062 mW. At maximum pump power, the mode-locked THDFL has output power and pulse energy of 15 mW and 1.66 nJ, respectively. Our results demonstrate the TiO2 can be used promisingly in ultrafast photonics applications.

  11. Generation and evolution of mode-locked noise-like square-wave pulses in a large-anomalous-dispersion Er-doped ring fiber laser.

    PubMed

    Liu, Jun; Chen, Yu; Tang, Pinghua; Xu, Changwen; Zhao, Chujun; Zhang, Han; Wen, Shuangchun

    2015-03-09

    In a passively mode-locked Erbium-doped fiber laser with large anomalous-dispersion, we experimentally demonstrate the formation of noise-like square-wave pulse, which shows quite different features from conventional dissipative soliton resonance (DSR). The corresponding temporal and spectral characteristics of a variety of operation states, including Q-switched mode-locking, continuous-wave mode-locking and Raman-induced noise-like pulse near the lasing threshold, are also investigated. Stable noise-like square-wave mode-locked pulses can be obtained at a fundamental repetition frequency of 195 kHz, with pulse packet duration tunable from 15 ns to 306 ns and per-pulse energy up to 200 nJ. By reducing the linear cavity loss, stable higher-order harmonic mode-locking had also been observed, with pulse duration ranging from 37 ns at the 21st order harmonic wave to 320 ns at the fundamental order. After propagating along a piece of long telecom fiber, the generated square-wave pulses do not show any obvious change, indicating that the generated noise-like square-wave pulse can be considered as high-energy pulse packet for some promising applications. These experimental results should shed some light on the further understanding of the mechanism and characteristics of noise-like square-wave pulses.

  12. Generation of 73 fs pulses from a diode pumped Kerr-lens mode-locked Yb:YCa₄O(BO₃)₃ laser.

    PubMed

    Gao, Ziye; Zhu, Jiangfeng; Tian, Wenlong; Wang, Junli; Zhang, Zhiguo; Wei, Zhiyi; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

    2014-10-15

    We realized a stable Kerr-lens mode-locked operation in a Yb:YCa₄O(BO₃)₃ laser. Pulses as short as 73 fs were generated at the central wavelength of 1043 nm, with a bandwidth of 19 nm. The femtosecond oscillator operating at a repetition rate of 110 MHz delivers an average output power of 70 mW under 3 W diode pump power. To the best of our knowledge, this is the first demonstration of a pure Kerr-lens mode-locked operation in a diode-pumped Yb:YCa₄O(BO₃)₃ laser.

  13. High energy, single-polarized, single-transverse-mode, nanosecond pulses generated by a multi-stage Yb-doped photonic crystal fiber amplifier

    NASA Astrophysics Data System (ADS)

    Shen, Xinglai; Zhang, Haitao; Hao, He; Li, Dan; Li, Qinghua; Yan, Ping; Gong, Mali

    2015-06-01

    We report the construction of a cascaded fiber amplifier where a 40-μm-core-diameter photonic crystal fiber is utilized in the main amplifier stage. Single-transverse-mode, linearly-polarized, 7.5 ns pulses with 1.5 mJ energy, 123 kW peak power and 10 nm spectral bandwidth centered at 1062 nm are generated. To our knowledge, the pulse energy we obtain is the highest from 40-μm-core-diameter photonic crystal fibers, and also the highest for long pulses (>1 ns) with linear polarization and single transverse mode.

  14. Coordination modes of bidentate lornoxicam drug with some transition metal ions. Synthesis, characterization and in vitro antimicrobial and antibreastic cancer activity studies.

    PubMed

    Mahmoud, Walaa H; Mohamed, Gehad G; El-Dessouky, Maher M I

    2014-03-25

    The NSAID lornoxicam (LOR) drug was used for complex formation reactions with different metal salts like Cr(III), Mn(II), Fe(III) and Ni(II) chlorides and Fe(II), Co(II), Cu(II) and Zn(II) borates. Mononuclear complexes of these metals are obtained that coordinated to NO sites of LOR ligand molecule. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, IR, UV-Vis, (1)H NMR, mass, electronic spectra, magnetic susceptibility and ESR spectral studies, conductivity measurements, thermogravimetric analyses (TG-DTG) and further confirmed by X-ray powder diffraction. The activation thermodynamic parameters are calculated using Coats-Redfern and Horowitz-Metzger methods. The data show that the complexes have composition of ML2 type except for Fe(II) where the type is [ML3]. The electronic absorption spectral data of the complexes suggest an octahedral geometry around the central metal ion for all the complexes. The antimicrobial data reveals that LOR ligand in solution show inhibition capacity less or sometimes more than the corresponding complexes against all the species under study. In order to establish their future potential in biomedical applications, anticancer evaluation studies against standard breast cancer cell lines (MCF7) was performed using different concentrations. The obtained results indicate high inhibition activity for Cr(III), Fe(II) and Cu(II) complexes against breast cancer cell line (MCF7) and recommends them for testing as antitumor agents.

  15. Coordination modes of bidentate lornoxicam drug with some transition metal ions. Synthesis, characterization and in vitro antimicrobial and antibreastic cancer activity studies

    NASA Astrophysics Data System (ADS)

    Mahmoud, Walaa H.; Mohamed, Gehad G.; El-Dessouky, Maher M. I.

    2014-03-01

    The NSAID lornoxicam (LOR) drug was used for complex formation reactions with different metal salts like Cr(III), Mn(II), Fe(III) and Ni(II) chlorides and Fe(II), Co(II), Cu(II) and Zn(II) borates. Mononuclear complexes of these metals are obtained that coordinated to NO sites of LOR ligand molecule. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, IR, UV-Vis, 1H NMR, mass, electronic spectra, magnetic susceptibility and ESR spectral studies, conductivity measurements, thermogravimetric analyses (TG-DTG) and further confirmed by X-ray powder diffraction. The activation thermodynamic parameters are calculated using Coats-Redfern and Horowitz-Metzger methods. The data show that the complexes have composition of ML2 type except for Fe(II) where the type is [ML3]. The electronic absorption spectral data of the complexes suggest an octahedral geometry around the central metal ion for all the complexes. The antimicrobial data reveals that LOR ligand in solution show inhibition capacity less or sometimes more than the corresponding complexes against all the species under study. In order to establish their future potential in biomedical applications, anticancer evaluation studies against standard breast cancer cell lines (MCF7) was performed using different concentrations. The obtained results indicate high inhibition activity for Cr(III), Fe(II) and Cu(II) complexes against breast cancer cell line (MCF7) and recommends them for testing as antitumor agents.

  16. Frequency-switchable microwave generation based on a dual-wavelength single-longitudinal-mode fiber laser incorporating a high-finesse ring filter.

    PubMed

    Pan, Shilong; Yao, Jianping

    2009-07-06

    A wavelength-switchable single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber laser (EDFL) incorporating a novel high-finesse ring filter is proposed and demonstrated. The ring filter consists of two optical couplers and a section of pumped erbium-doped fiber (EDF). Thanks to the gain generated by the EDF, the ring filter has spectral response with a high finesse. The incorporation of the ring filter leads to the suppression of undesirable modes in the dual-wavelength EDFL. An experiment is carried out. Two SLM wavelengths are generated. The side mode suppression ratio is greater than 50 dB. The wavelength spacing of the two wavelengths is tunable with a tuning step of approximately 10 GHz. A frequency switchable microwave signal from approximately 10 to approximately 40 GHz is thus generated by beating the two wavelengths at a photodetector (PD). The spectral width of the generated microwave signal is measured to be less than 5 kHz.

  17. 320 fs pulse generation from an ultrafast laser inscribed waveguide laser mode-locked by a nanotube saturable absorber

    NASA Astrophysics Data System (ADS)

    Beecher, S. J.; Thomson, R. R.; Psaila, N. D.; Sun, Z.; Hasan, T.; Rozhin, A. G.; Ferrari, A. C.; Kar, A. K.

    2010-09-01

    Ultrafast laser inscription is used to fabricate the gain element for a mode-locked Er-doped bismuthate glass waveguide laser. Mode-locking is initiated and stabilized by the use of a single wall carbon nanotube saturable absorber. The waveguide laser produces 320 fs pulses at 1.56 μm with a pulse repetition rate of 40 MHz and average output power of 1.25 mW.

  18. Generation of continuous-wave terahertz radiation using a two-mode titanium sapphire laser containing an intracavity Fabry-Perot etalon

    NASA Astrophysics Data System (ADS)

    Stone, Michael R.; Naftaly, Mira; Miles, Robert E.; Mayorga, Ivan C.; Malcoci, Andrei; Mikulics, Martin

    2005-05-01

    Continuous-wave terahertz (THz) radiation was generated by photomixing two modes of a titanium sapphire laser. The laser was induced to oscillate on two modes by placing a Fabry-Perot etalon in the laser resonator. The frequency of terahertz radiation, which was equal to the difference frequency of the two modes, was varied by adjusting the free spectral range (FSR) of the etalon. Photomixing was performed by logarithmic spiral antennas fabricated on low-temperature-grown GaAs; and the emitted THz radiation was characterized. The THz power, measured by a Golay cell, was 1μW at 0.3THz and 0.7μW at 0.5THz. The THz frequency, as determined by a Fourier transform interferometer, was seen to correspond to the etalon FSR. The current-voltage characteristics of photomixers were also determined, and photocurrent modulation was observed by the autocorrelation of the laser beam.

  19. Generation of Q-switched mode locking controlled rectangular noise-like soliton bunching in a Tm-doped fiber laser.

    PubMed

    Qiao, Tian; Chen, Weicheng; Lin, Wei; Yang, Zhongmin

    2016-08-08

    We report on an interesting phenomenon of the combination of Q-switched mode locked pulses (QSMLP) and rectangular noise-like pulses (RNLP) as a unit in a Tm-doped ring fiber laser which contains a Fabry-Perot (F-P) subcavity based on the nonlinear polarization evolution (NPE) technique. The RNLP and QSMLP are independently generated in the ring cavity and F-P subcavity, respectively. A notable characteristic is that the physical parameters of RNLP, e.g. repetition rate and pulse duration, are controlled by QSMLP. Thus, they form as a composite bunching, which is termed as "Q-switched mode locking controlled rectangular noise-like soliton bunching (QRNSB)". Further investigation shows that the existence of QRNSB only occurs in high pumping conditions, while both fundamental mode-locking pulses and the coexistence of QSMLP and solitons are achieved in low pumping ones. Our work can enrich the understanding of the nonlinear dynamics in fiber lasers.

  20. High energy pulses generation with giant spectrum bandwidth and submegahertz repetition rate from a passively mode-locked Yb-doped fiber laser in all normal dispersion cavity

    NASA Astrophysics Data System (ADS)

    Lin, J.-H.; Wang, D.; Lin, K.-H.

    2011-01-01

    Robust passively mode-locked pulse generation with low pulse repetition rate and giant spectrum bandwidth in an all-fiber, all-normal-dispersion ytterbium-doped fiber laser has been experimentally demonstrated using nonlinear polarization evolution technique. The highest pulse energy over 20 nJ with spectrum bandwidth over 50 nm can be experimentally obtained at 175 mW pump power. The mode-locked pulses reveal broadened 3-dB pulsewidth about several nanosecond and widened pedestal in time trace that is resulted from enormous dispersion in laser cavity and gain dynamics. At certain mode-locking state, a spectrum gap around 1056 nm are observed between the three and four energy levels of Yb-doped fiber laser. By properly rotating the polarization controller, the gap can be eliminated due to four-wave mixing to produce more flattened spectrum output.

  1. Poisson Coordinates.

    PubMed

    Li, Xian-Ying; Hu, Shi-Min

    2013-02-01

    Harmonic functions are the critical points of a Dirichlet energy functional, the linear projections of conformal maps. They play an important role in computer graphics, particularly for gradient-domain image processing and shape-preserving geometric computation. We propose Poisson coordinates, a novel transfinite interpolation scheme based on the Poisson integral formula, as a rapid way to estimate a harmonic function on a certain domain with desired boundary values. Poisson coordinates are an extension of the Mean Value coordinates (MVCs) which inherit their linear precision, smoothness, and kernel positivity. We give explicit formulas for Poisson coordinates in both continuous and 2D discrete forms. Superior to MVCs, Poisson coordinates are proved to be pseudoharmonic (i.e., they reproduce harmonic functions on n-dimensional balls). Our experimental results show that Poisson coordinates have lower Dirichlet energies than MVCs on a number of typical 2D domains (particularly convex domains). As well as presenting a formula, our approach provides useful insights for further studies on coordinates-based interpolation and fast estimation of harmonic functions.

  2. Validation of Space Weather Models at Community Coordinated Modeling Center

    NASA Technical Reports Server (NTRS)

    Kuznetsova, M. M.; Pulkkinen, A.; Rastaetter, L.; Hesse, M.; Chulaki, A.; Maddox, M.

    2011-01-01

    The Community Coordinated Modeling Center (CCMC) is a multiagency partnership, which aims at the creation of next generation space weather modes. CCMC goal is to support the research and developmental work necessary to substantially increase space weather modeling capabilities and to facilitate advanced models deployment in forecasting operations. The CCMC conducts unbiased model testing and validation and evaluates model readiness for operational environment. The presentation will demonstrate the recent progress in CCMC metrics and validation activities.

  3. Coordinated regulation of nitrogen supply mode and initial cell density for energy storage compounds production with economized nitrogen utilization in a marine microalga Isochrysis zhangjiangensis.

    PubMed

    Chi, Lei; Yao, Changhong; Cao, Xupeng; Xue, Song

    2016-01-01

    Lipids and carbohydrates are main energy storage compounds (ESC) of microalgae under stressed conditions and they are potential feedstock for biofuel production. Yet, the sustainable and commercially successful production of ESC in microalgae needs to consider nitrogen utilization efficiency. Here the impact of different initial cell densities (ICDs) on ESC accumulation in Isochrysis zhangjiangensis under two nitrogen supply modes (an initially equal concentration of nitrogen per-cell in the medium (N1) and an equal total concentration of nitrogen in the culture system (N2)) were investigated. The results demonstrated that the highest ESC yield (1.36gL(-1)) at N1, which included a maximal nitrogen supply in the cultivation system, and the highest ESC content (66.5%) and ESC productivity per mass of nitrogen (3.28gg(-1) (N) day(-1)) at N2, were all obtained under a high ICD of 8.0×10(6)cellsmL(-1). Therefore I. zhangjiangensis qualifies for ESC-enriched biomass production with economized nitrogen utilization.

  4. From knowledge generation to knowledge archive. A general strategy using TOPS-MODE with DEREK to formulate new alerts for skin sensitization.

    PubMed

    Estrada, Ernesto; Patlewicz, Grace; Gutierrez, Yaquelin

    2004-01-01

    A general strategy for knowledge flow concerning skin sensitization based on the combined use of TOPS-MODE and DEREK expert system is proposed. TOPS-MODE is used as a knowledge generator, while DEREK represents the knowledge archive. A TOPS-MODE classification model allows the identification of structural fragments and groups responsible for strong/moderate skin sensitization. These structural contributions are sorted, analyzed, and graphically displayed in an appropriate way allowing the identification of several structural alerts for skin sensitization. Nine structural alerts already implemented in DEREK are identified using this strategy. They comprise, among others, alkyl halides, aldehydes, alpha,beta-unsaturated compounds, aromatic amines, phenols, hydroquinone, isothiazolinone, and alkyl sulfonates. Four new hypotheses are generated using TOPS-MODE structural contributions to skin sensitization, which are not recognized as structural alerts by DEREK. They include the reduction of aromatic nitro groups and epoxidation reaction of double bonds as metabolic activation steps that can lead to reactive haptens which can trigger the skin sensitization mechanism. Another new alert is based on 1,2,5-thiadiazole-1,1-dioxide for which we have identified a possible mechanism explaining its strong skin sensitization profile. It is based on the existence of a tautomeric equilibrium and further reaction with nucleophiles, which are both supported by experimental evidence. Finally, we have identified a possible new mechanism for the skin sensitization of nonreactive compounds, which involves the formation of noncovalent complexes with proteins in a processing- and metabolism-independent way.

  5. Generation of 103 fs mode-locked pulses by a gain linewidth-variable Nd,Y:CaF2 disordered crystal.

    PubMed

    Qin, Z P; Xie, G Q; Ma, J; Ge, W Y; Yuan, P; Qian, L J; Su, L B; Jiang, D P; Ma, F K; Zhang, Q; Cao, Y X; Xu, J

    2014-04-01

    We have demonstrated a diode-pumped passively mode-locked femtosecond Nd,Y:CaF2 disordered crystal laser for the first time to our knowledge. By choosing appropriate Y-doping concentration, a broad fluorescence linewidth of 31 nm has been obtained from the gain linewidth-variable Nd,Y:CaF2 crystal. With the Nd,Y:CaF2 disordered crystal as gain medium, the mode-locked laser generated pulses with pulse duration as short as 103 fs, average output power of 89 mW, and repetition rate of 100 MHz. To our best knowledge, this is the shortest pulse generated from Nd-doped crystal lasers so far. The research results show that the Nd,Y:CaF2 disordered crystal will be a potential alternative as gain medium of repetitive chirped pulse amplification for high-peak-power lasers.

  6. Generation of 48-fs pulses and measurement of crystal dispersion by using a regeneratively initiated self-mode-locked chromium-doped forsterite laser

    NASA Astrophysics Data System (ADS)

    Sennaroglu, Alphan; Pollock, Clifford R.; Nathel, Howard

    1993-05-01

    A regeneratively initiated self-mode-locked chromium-doped forsterite laser operated at 3.5 C is described. By employing intracavity negative-group-velocity dispersion compensation, nearly transform-limited femtosecond pulses of 48-fs (FWHM) duration were generated with average TEM(00) output powers of 380 mW at 1.23 micron. Regenerative initiation provides improvement in the output stability and ease of operation compared with fixed-frequency acousto-optic modulators. By tuning the mode-locked laser in the range 1.21-1.26 micron, estimated values for forsterite dispersion constants have also been obtained for the first time to our knowledge. The demonstrated power and stability open the door to applications such as efficient second-harmonic generation.

  7. Near-IR supercontinuum generation based on a telecom single-mode fibre in an all-fibre format, and its power combining

    SciTech Connect

    Rumao Tao; Xiaolin Wang; Xiao, H; Zhou, P; Jing Hou

    2014-04-28

    Near-IR supercontinuum (SC) is generated based on a standard telecommunication single-mode (SM) fibre in an all-fibre format. The observed spectrum covers the spectral range from 1050 nm to 1700 nm. High-efficiency combining of the SC power is demonstrated for the first time, and the spectral SC properties are shown to be maintained after power combining. The results may find applications in sensing, spectroscopy and medicine. (control of laser radiation parameters)

  8. Controllable generation of two-mode-entangled states in two-resonator circuit QED with a single gap-tunable superconducting qubit

    NASA Astrophysics Data System (ADS)

    Ma, Sheng-Li; Li, Zhen; Fang, Ai-Ping; Li, Peng-Bo; Gao, Shao-Yan; Li, Fu-Li

    2014-12-01

    We study controllable generation of two-mode-entangled states in a circuit QED setup, which consists of two spatially separated superconducting transmission line resonators and a single gap-tunable superconducting qubit. Two sharp coupling sidebands are induced when the artificial atom is suitably driven by a bichromatic microwave field. The two resonators can have squeezing-type interactions with the qubit via the coupling sidebands. If the two resonators are not degenerate, we show that the two resonators can be cooled down into the two-mode squeezed vacuum via dissipation of the qubit. The generation of the two-mode squeezed state is based on a dissipative state-engineering process, which explores the energy relaxation of the qubit as a resource. Moreover, the scheme does not need both the specific preparation of the initial state and the designed special dynamical process of the system. If the resonators are degenerate, we show that entangled coherent states of the resonators can be generated by use of the unitary dynamical evolution process of the system and the state-projection measurement. Moreover, macro entangled coherent states of the resonators with huge photons can in principle be created if the resonators and the qubit have sufficiently long lifetimes. The present scheme has two remarkable features: (1) only a single qubit is used in the generation of the two-mode squeezed state; and (2) the ultrastrong coupling condition and initializing the resonators in coherent states are not required. These make the present scheme more simple and feasible in experimental implementation.

  9. Simultaneous self-starting additive pulse mode-locking and second harmonic generation of an Nd:YAG laser using self-organised germanosilicate optical fibres

    NASA Astrophysics Data System (ADS)

    Bernardin, J. P.; Lawandy, N. M.

    1991-08-01

    The simultaneous operation of self-starting additive pulse mode-locking and optical fiber second harmonic generation of an Nd:YAG laser resulting in picosecond radiation at 1.06 mm and 532 nm was demonstrated. The IR pulses were measured to be 5 ps in duration, and the green pulses are expected to be approximately 3.5 ps due to the nonlinear interaction. Effects of self-modulation and cross-phase modulation on the conversion efficiency are discussed.

  10. CMB anisotropies from a gradient mode

    SciTech Connect

    Mirbabayi, Mehrdad; Zaldarriaga, Matias E-mail: matiasz@ias.edu

    2015-03-01

    A linear gradient mode must have no observable dynamical effect on short distance physics. We confirm this by showing that if there was such a gradient mode extending across the whole observable Universe, it would not cause any hemispherical asymmetry in the power of CMB anisotropies, as long as Maldacena's consistency condition is satisfied. To study the effect of the long wavelength mode on short wavelength modes, we generalize the existing second order Sachs-Wolfe formula in the squeezed limit to include a gradient in the long mode and to account for the change in the location of the last scattering surface induced by this mode. Next, we consider effects that are of second order in the long mode. A gradient mode Φ = q⋅x generated in Single-field inflation is shown to induce an observable quadrupole moment. For instance, in a matter-dominated model it is equal to Q = 5(q⋅x){sup 2}/18. This quadrupole can be canceled by superposition of a quadratic perturbation. The result is shown to be a nonlinear extension of Weinberg's adiabatic modes: a long-wavelength physical mode which looks locally like a coordinate transformation.

  11. CMB anisotropies from a gradient mode

    NASA Astrophysics Data System (ADS)

    Mirbabayi, Mehrdad; Zaldarriaga, Matias

    2015-03-01

    A linear gradient mode must have no observable dynamical effect on short distance physics. We confirm this by showing that if there was such a gradient mode extending across the whole observable Universe, it would not cause any hemispherical asymmetry in the power of CMB anisotropies, as long as Maldacena's consistency condition is satisfied. To study the effect of the long wavelength mode on short wavelength modes, we generalize the existing second order Sachs-Wolfe formula in the squeezed limit to include a gradient in the long mode and to account for the change in the location of the last scattering surface induced by this mode. Next, we consider effects that are of second order in the long mode. A gradient mode Φ = qṡx generated in Single-field inflation is shown to induce an observable quadrupole moment. For instance, in a matter-dominated model it is equal to Q = 5(qṡx)2/18. This quadrupole can be canceled by superposition of a quadratic perturbation. The result is shown to be a nonlinear extension of Weinberg's adiabatic modes: a long-wavelength physical mode which looks locally like a coordinate transformation.

  12. Supercontinuum generation from a multiple-ring-holes tellurite microstructured optical fiber pumped by a 2 μm mode-locked picosecond fiber laser.

    PubMed

    Deng, Dinghuan; Gao, Weiqing; Liao, Meisong; Duan, Zhongchao; Cheng, Tonglei; Suzuki, Takenobu; Ohishi, Yasutake

    2013-06-01

    Supercontinuum (SC) generation from a highly nonlinear tellurite microstructured optical fiber with multiple rings of holes was demonstrated by pumping with a 2 μm mode-locked picosecond fiber laser. The chromatic dispersion of the fiber was measured with a homemade white-light spectral interferometer in a wide wavelength range and agreed with the theoretical calculation. Although the pumped wavelength was far from the zero dispersion wavelength, with flat dispersion profile of the fiber in the anomalous dispersion, the SC could be expanded from 650 to 2850 nm with launched pulse energy of several hundred picojoules. Simulations of SC generation agreed with the experimental results.

  13. Enhanced ELF wave generation efficiency using ‘O’ Mode HF heating of the ionosphere: An instrumental explanation

    NASA Astrophysics Data System (ADS)

    Barr, Richard; Stubbe, P.; Rietveld, M. T.; Nielsen, E.

    In [Barr et al. 1997] we presented ELF signals received near the Tromsø ionospheric heater facility when the heater radiated HF signals amplitude modulated by a 505Hz square wave. Square wave modulation enabled simultaneous multiple frequency measurements to be made of the signals radiated from the ionosphere as the heater was switched to radiate both ‘X’ and ‘O’ mode HF waves. We found that whereas the first 3 odd harmonics of the square wave (≥ 1515 Hz) all showed the accepted behaviour of reduced wave excitation on switching from ‘X’ to ‘O’ mode HF heating, the fundamental frequency showed enhanced excitation of more than 10dB with ‘O’ mode heating. These observations were given an ionospheric explanation in terms of a change from Hall to Pedersen current modulation with the change from ‘X’ to ‘O’ mode HF heating. We present here an alternative analysis, which has both instrumental and ionospheric components and is also able to explain the observations.

  14. The q-profile effect on high-order harmonic q = 1 tearing mode generation during sawtooth crashes

    SciTech Connect

    Wang Zhengxiong; Wei Lai; Wang Xiaogang

    2012-06-15

    The effect of q-profiles on the excitation of high-order harmonic q=1 tearing modes during sawtooth crashes is investigated by a collisionless fluid model with the electron inertia term in Ohm's law. It is found that for a flat q-profile in the core region, the high-order harmonics, such as m/n=2/2 and/or m/n=3/3 modes, comparable to or stronger than the m/n=1/1 component, can be excited during tokamak sawteeth. The stronger the magnetic shear on the q=1 surface is, the more unstable the higher-m modes are. For smoothly monotonously increased q-profiles, a lower q value on the plasma edge tends to easily excite higher-m harmonics at the same level as the m = 1 mode simultaneously. The spatial characteristics of the eigenmodes in the cases with the typical q-profiles are also discussed. In addition, the basic feature of the magnetic island structures in the nonlinear evolution is numerically obtained, which is consistent qualitatively with the experimentally reconstructed phenomenon.

  15. Short wavelength turbulence generated by shear in the quiescent H-mode edge on DIII–D

    SciTech Connect

    Rost, J. C.; Porkolab, M.; Dorris, J.; Burrell, K. H.

    2014-06-15

    A region of turbulence with large radial wavenumber (k{sub r}ρ{sub s}>1) is found in the high-shear portion of the plasma edge in Quiescent H-mode (QH-mode) on DIII–D using the Phase Contrast Imaging (PCI) diagnostic. At its peak outside the minimum of the E{sub r} well, the turbulence exhibits large amplitude n{sup ~}/n∼40%, with large radial wavenumber |k{sup ¯}{sub r}/k{sup ¯}{sub θ}|∼11 and short radial correlation length L{sub r}/ρ{sub i}∼0.2. The turbulence inside the E{sub r} well minimum is characterized by the opposite sign in radial wavenumber from that of turbulence outside the minimum, consistent with the expected effects of velocity shear. The PCI diagnostic provides a line-integrated measurement of density fluctuations, so data are taken during a scan of plasma position at constant parameters to allow the PCI to sample a range in k{sub r}/k{sub θ}. Analysis of the Doppler shift and plasma geometry allows the turbulence to be localized to a narrow region 3 mm inside the last closed flux surface, outside the minimum of the E{sub r} well. The turbulence amplitude and radial wavenumber and correlation length are determined by fitting the PCI results with a simple non-isotropic turbulence model with two regions of turbulence. These PCI observations, made in QH-mode, are qualitatively similar to those made in standard edge localized modes (ELM)-free H-mode and between ELMs, suggesting a similar role for large k{sub r} turbulence there.

  16. Short wavelength turbulence generated by shear in the quiescent H-mode edge on DIII-D

    NASA Astrophysics Data System (ADS)

    Rost, J. C.; Porkolab, M.; Dorris, J.; Burrell, K. H.

    2014-06-01

    A region of turbulence with large radial wavenumber (krρs>1) is found in the high-shear portion of the plasma edge in Quiescent H-mode (QH-mode) on DIII-D using the Phase Contrast Imaging (PCI) diagnostic. At its peak outside the minimum of the Er well, the turbulence exhibits large amplitude n ˜/n˜40%, with large radial wavenumber |k¯r/k¯θ|˜11 and short radial correlation length Lr/ρi˜0.2. The turbulence inside the Er well minimum is characterized by the opposite sign in radial wavenumber from that of turbulence outside the minimum, consistent with the expected effects of velocity shear. The PCI diagnostic provides a line-integrated measurement of density fluctuations, so data are taken during a scan of plasma position at constant parameters to allow the PCI to sample a range in kr/kθ. Analysis of the Doppler shift and plasma geometry allows the turbulence to be localized to a narrow region 3 mm inside the last closed flux surface, outside the minimum of the Er well. The turbulence amplitude and radial wavenumber and correlation length are determined by fitting the PCI results with a simple non-isotropic turbulence model with two regions of turbulence. These PCI observations, made in QH-mode, are qualitatively similar to those made in standard edge localized modes (ELM)-free H-mode and between ELMs, suggesting a similar role for large kr turbulence there.

  17. Using a model to assess the role of the spatiotemporal pattern of inhibitory input and intrasegmental electrical coupling in the intersegmental and side-to-side coordination of motor neurons by the leech heartbeat central pattern generator.

    PubMed

    García, Paul S; Wright, Terrence M; Cunningham, Ian R; Calabrese, Ronald L

    2008-09-01

    Previously we presented a quantitative description of the spatiotemporal pattern of inhibitory synaptic input from the heartbeat central pattern generator (CPG) to segmental motor neurons that drive heartbeat in the medicinal leech and the resultant coordination of CPG interneurons and motor neurons. To begin elucidating the mechanisms of coordination, we explore intersegmental and side-to-side coordination in an ensemble model of all heart motor neurons and their known synaptic inputs and electrical coupling. Model motor neuron intrinsic properties were kept simple, enabling us to determine the extent to which input and electrical coupling acting together can account for observed coordination in the living system in the absence of a substantive contribution from the motor neurons themselves. The living system produces an asymmetric motor pattern: motor neurons on one side fire nearly in synchrony (synchronous), whereas on the other they fire in a rear-to-front progression (peristaltic). The model reproduces the general trends of intersegmental and side-to-side phase relations among motor neurons, but the match with the living system is not quantitatively accurate. Thus realistic (experimentally determined) inputs do not produce similarly realistic output in our model, suggesting that motor neuron intrinsic properties may contribute to their coordination. By varying parameters that determine electrical coupling, conduction delays, intraburst synaptic plasticity, and motor neuron excitability, we show that the most important determinant of intersegmental and side-to-side phase relations in the model was the spatiotemporal pattern of synaptic inputs, although phasing was influenced significantly by electrical coupling.

  18. Supercontinuum generation based on all-normal-dispersion Yb-doped fiber laser mode-locked by nonlinear polarization rotation: Influence of seed's output port

    NASA Astrophysics Data System (ADS)

    Xiao, Xiaosheng; Hua, Yi

    2016-10-01

    All-normal-dispersion (ANDi) mode-locked Yb-doped fiber laser is a promising seed source for supercontinuum (SC) generation, due to its compact structure and broadband output. The influences of output ports of the ANDi laser mode-locked by nonlinear polarization rotation (NPR), on the generated SC are investigated. Two output ports of ANDi laser are considered, one of which is the conventional nonlinear polarization rotation (NPR) port and the other is extracted from a coupler after the NPR port. It is found that, the SC originated from the coupler port is much broader than that from the NPR port, which is validated by lots of experiments with different output parameters. Furthermore, the conclusion is verified and generalized to general ANDi lasers by numerical simulations, because the output pulse from coupler port could be cleaner than that from NPR port. Besides, there are no significant differences in the phase coherence and temporal stability between the SCs generated from both ports. Hence for the SC generation based on ANDi laser, it is preferred to use the pulse of coupler port (i.e. pulse after NPR port) serving as the seed source.

  19. Generation of coherent spin-wave modes in yttrium iron garnet microdiscs by spin-orbit torque.

    PubMed

    Collet, M; de Milly, X; d'Allivy Kelly, O; Naletov, V V; Bernard, R; Bortolotti, P; Ben Youssef, J; Demidov, V E; Demokritov, S O; Prieto, J L; Muñoz, M; Cros, V; Anane, A; de Loubens, G; Klein, O

    2016-01-27

    In recent years, spin-orbit effects have been widely used to produce and detect spin currents in spintronic devices. The peculiar symmetry of the spin Hall effect allows creation of a spin accumulation at the interface between a metal with strong spin-orbit interaction and a magnetic insulator, which can lead to a net pure spin current flowing from the metal into the insulator. This spin current applies a torque on the magnetization, which can eventually be driven into steady motion. Tailoring this experiment on extended films has proven to be elusive, probably due to mode competition. This requires the reduction of both the thickness and lateral size to reach full damping compensation. Here we show clear evidence of coherent spin-orbit torque-induced auto-oscillation in micron-sized yttrium iron garnet discs of thickness 20 nm. Our results emphasize the key role of quasi-degenerate spin-wave modes, which increase the threshold current.

  20. Single-polarization noise-like pulse generation from a hybrid mode-locked thulium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Liu, Shuo; Yan, Feng-Ping; Feng, Ting; Zhang, Lu-Na; Bai, Zhuo-Ya; Zhou, Hong; Hou, Yafei; Zhang, Ning

    2017-04-01

    A hybrid mode-locked thulium-doped fiber laser incorporating a nonlinear optical loop mirror and a nonlinear polarization rotation effect is proposed in the 2 μm band for the first time. By adjusting two polarization controllers, a stable single-polarization noise-like (SPNL) pulse operation is obtained. The SPNL pulse could work steadily for at least 400 min. At a launched pump power of 3.52 W, the hybrid mode-locked SPNL pulse centers at 2007 nm with an optical full width at half maximum of 20 nm, a polarization extinction ratio of 26.3 dB, a coherence spike width of 258 fs and a pulse energy of 42.11 nJ, respectively.

  1. Effects of polarization mode dispersion on polarization-entangled photons generated via broadband pumped spontaneous parametric down-conversion

    NASA Astrophysics Data System (ADS)

    Lim, Hyang-Tag; Hong, Kang-Hee; Kim, Yoon-Ho

    2016-05-01

    An inexpensive and compact frequency multi-mode diode laser enables a compact two-photon polarization entanglement source via the continuous wave broadband pumped spontaneous parametric down-conversion (SPDC) process. Entanglement degradation caused by polarization mode dispersion (PMD) is one of the critical issues in optical fiber-based polarization entanglement distribution. We theoretically and experimentally investigate how the initial entanglement is degraded when the two-photon polarization entangled state undergoes PMD. We report an effect of PMD unique to broadband pumped SPDC, equally applicable to pulsed pumping as well as cw broadband pumping, which is that the amount of the entanglement degradation is asymmetrical to the PMD introduced to each quantum channel. We believe that our results have important applications in long-distance distribution of polarization entanglement via optical fiber channels.

  2. Generations.

    PubMed

    Chambers, David W

    2005-01-01

    Groups naturally promote their strengths and prefer values and rules that give them an identity and an advantage. This shows up as generational tensions across cohorts who share common experiences, including common elders. Dramatic cultural events in America since 1925 can help create an understanding of the differing value structures of the Silents, the Boomers, Gen Xers, and the Millennials. Differences in how these generations see motivation and values, fundamental reality, relations with others, and work are presented, as are some applications of these differences to the dental profession.

  3. Generation of 54 Fs Laser Pulses from a Diode Pumped Kerr-Lens Mode-Locked Yb:LSO Laser

    NASA Astrophysics Data System (ADS)

    Tian, Wen-Long; Wang, Zhao-Hua; Zhu, Jiang-Feng; Wei, Zhi-Yi; Zheng, Li-He; Xu, Xiao-Dong; Xu, Jun

    2015-02-01

    A diode pumped Kerr-lens mode-locked femtosecond Yb:LSO laser is experimentally demonstrated for the first time. The 54 fs laser pulses at central wavelength of 1052 nm with a bandwidth of 22.5 nm are obtained at the repetition rate of 113 MHz. To the best of our knowledge, this is the shortest pulse duration ever produced from the Yb-doped orthosilicates lasers family.

  4. Generation of higher-order atomic dipole squeezing in a high-Q micromaser cavity. (VII). Entangled two-mode coherent states

    NASA Astrophysics Data System (ADS)

    Xie, Rui-Hua; Rao, Qin

    2002-12-01

    In our preceding paper V, we investigated the generation of higher-order atomic dipole squeezing (HOADS) in a nondegenerate two-photon Jaynes-Cummings model (NTPJCM) in the presence of Stark shift. In this paper, we continue to study HOADS in this model but focus on the specific cases that the radiation field is initially prepared in a two-mode entangled state (e.g., two-mode squeezed vacuum state, two-mode Perelomov and Barut-Girardello coherent states). It is found that increasing the fixed difference in the photon numbers of the two-mode entangled states of the radiation field could decrease the squeeze duration and shorten the squeeze period, and the detuning may lead to much effective HOADS by properly adjusting certain value. In general, the Stark shift has a destructive effect on HOADS, but the combined effect of the detuning and Stark shift could increase the squeeze duration and lead to regular and periodical HOADS pattern. The influence of atomic coherence on HOADS is also examined in detail.

  5. Expression of picogram sensitive bending modes in piezoelectric cantilever sensors with nonuniform electric fields generated by asymmetric electrodes

    NASA Astrophysics Data System (ADS)

    Johnson, Blake N.; Mutharasan, Raj

    2010-12-01

    Single-layer uniform cross-sectioned piezoelectric macro-cantilevers fabricated with an asymmetric electrode configuration enabled electrical measurement of picogram-sensitive resonant bending modes in liquids. Bending modes were otherwise not electrically measurable without excitation by a nonuniform electric field created by the geometric asymmetry in electrode design used. Electrode modification was confirmed by energy-dispersive X-ray spectroscopy (EDS). Mass-change sensitivity was tested using both bulk density changes and surface chemisorption experiments in a continuous flow apparatus. Significant response to density changes as small as 0.004 g/mL was measured. A sensitivity limit of ˜1 picogram in liquid was determined from 1-dodecanethiol chemisorption experiments. The sensitivity decreased with chemisorbed mass and was log-linear over five orders of magnitude. The observed resonance responses were in agreement with previously reported models of resonating cantilever sensors. This work demonstrates experimentally for the first time that introducing electrode asymmetry enables measurement of bending modes in cantilevers containing only a single piezoelectric layer.

  6. Gigahertz repetition rate, sub-femtosecond timing jitter optical pulse train directly generated from a mode-locked Yb:KYW laser.

    PubMed

    Yang, Heewon; Kim, Hyoji; Shin, Junho; Kim, Chur; Choi, Sun Young; Kim, Guang-Hoon; Rotermund, Fabian; Kim, Jungwon

    2014-01-01

    We show that a 1.13 GHz repetition rate optical pulse train with 0.70 fs high-frequency timing jitter (integration bandwidth of 17.5 kHz-10 MHz, where the measurement instrument-limited noise floor contributes 0.41 fs in 10 MHz bandwidth) can be directly generated from a free-running, single-mode diode-pumped Yb:KYW laser mode-locked by single-wall carbon nanotube-coated mirrors. To our knowledge, this is the lowest-timing-jitter optical pulse train with gigahertz repetition rate ever measured. If this pulse train is used for direct sampling of 565 MHz signals (Nyquist frequency of the pulse train), the jitter level demonstrated would correspond to the projected effective-number-of-bit of 17.8, which is much higher than the thermal noise limit of 50 Ω load resistance (~14 bits).

  7. COORDINATED AV.

    ERIC Educational Resources Information Center

    CLEAVES, PAUL C.; AND OTHERS

    THE INSTRUCTIONAL MATERIALS CENTER IS LOCATED IN THE LOCAL HIGH SCHOOL AND SUPPLIES ALL SCHOOLS IN THE AREA. AUDIOVISUAL EQUIPMENT ORDERS, AFTER SELECTIONS ARE MADE BY THE CLASSROOM TEACHER, ARE PROCESSED BY THE CENTER, CONFIRMED AND DELIVERED BY TRUCK THREE TIMES EACH WEEK. EACH SCHOOL HAS A BUILDING COORDINATOR WHO CHECKS THE ORDERS INTO THE…

  8. Ion beam enhancement in magnetically insulated ion diodes for high-intensity pulsed ion beam generation in non-relativistic mode

    SciTech Connect

    Zhu, X. P.; Zhang, Z. C.; Lei, M. K.; Pushkarev, A. I.

    2016-01-15

    High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, taking into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200–300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation.

  9. Ion beam enhancement in magnetically insulated ion diodes for high-intensity pulsed ion beam generation in non-relativistic mode

    NASA Astrophysics Data System (ADS)

    Zhu, X. P.; Zhang, Z. C.; Pushkarev, A. I.; Lei, M. K.

    2016-01-01

    High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, taking into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200-300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation.

  10. Low noise electro-optic comb generation by fully stabilizing to a mode-locked fiber comb.

    PubMed

    Kuse, Naoya; Schibli, Thomas R; Fermann, Martin E

    2016-07-25

    A fully stabilized EO comb is demonstrated by phase locking the two degrees of freedom of an EO comb to a low noise mode-locked fiber comb. Division/magnification of residual phase noise of locked beats is observed by measuring an out-of-loop beat. By phase locking the 200 th harmonics of the EO comb and a driving cw frequency to a fiber comb, a record low phase noise EO comb across +/- 200 harmonics (from 1544.8 nm to 1577.3 nm) is demonstrated.

  11. CONTROL OF LASER RADIATION PARAMETERS: Picosecond pulse generation in a passively mode-locked Bi-doped fibre laser

    NASA Astrophysics Data System (ADS)

    Krylov, Aleksandr A.; Kryukov, P. G.; Dianov, Evgenii M.; Okhotnikov, Oleg G.

    2009-10-01

    CW passive mode locking is achieved in a bismuth-doped fibre laser using a semiconductor saturable absorber mirror optimised for operation in the range 1100-1200 nm. The pump source is a cw ytterbium fibre laser (1075 nm, maximum output power of 2.7 W), and the pulse parameters can be tuned by varying the intracavity group velocity dispersion using a diffraction grating pair. Stable laser pulses are obtained with a duration down to τp approx 1.1 ps.

  12. Soliton collapse and bunched noise-like pulse generation in a passively mode-locked fiber ring laser.

    PubMed

    Tang, D; Zhao, L; Zhao, B

    2005-04-04

    A passively mode-locked soliton fiber ring laser with dispersion managed cavity is reported. The laser emits intense bunched noise-like pulses including the transform limited pulses. The optical spectrum of the laser emission has a bandwidth as broad as 32.10 nm. It was found that purely depending on the linear cavity phase delay the laser could be switched between the soliton operation and the noise-like pulse emission. Numerical simulations showed that the laser emission was caused by the combined effect of soliton collapse and positive cavity feedback in the laser.

  13. Evanescent field interaction of tapered fiber with graphene oxide in generation of wide-bandwidth mode-locked pulses

    NASA Astrophysics Data System (ADS)

    Ahmad, H.; Faruki, M. J.; Razak, M. Z. A.; Tiu, Z. C.; Ismail, M. F.

    2017-02-01

    Pulses with picosecond pulse widths are highly desired for high precision laser applications. A mode-locked pulse laser utilizing evanescent field interaction of a tapered fiber with graphene oxide (GO) is demonstrated. A homemade fabrication stage was used to fabricate the tapered fiber using systematic flame brushing and a GO solution was used to coat the microfiber using optical deposition technique. Pulse trains with a pulse width of 3.46 ps, a 3 dB optical bandwidth of 11.82 nm and a repetition rate of 920 kHz were obtained. The system has substantial potential for many crucial medical, communication, bio processing, military, and industrial applications.

  14. High power mid-infrared supercontinuum generation in a single-mode ZBLAN fiber pumped by amplified picosecond pulses at 2 μm

    NASA Astrophysics Data System (ADS)

    Liu, Kun; Liu, Jiang; Shi, Hongxing; Tan, Fangzhou; Jiang, Yijian; Wang, Pu

    2015-03-01

    We report high power all fiber mid-infrared (mid-IR) supercontinuum (SC) generation in a single-mode ZBLAN (ZrF4- BaF2-LaF3-AlF3-NaF) fiber with up to 21.8 W average output power from 1.9 to beyond 3.8 μm pumped by amplified picosecond pulses from a master oscillator power amplifier (MOPA) based on small-core single-mode thulium-doped fiber (TDF) with injected seed pulse width of 24 ps and repetition of 93.6 MHz at 1963 nm. The optical-optical conversion efficiency from the 793 nm pump laser of the last stage thulium-doped fiber amplifier (TDFA) to mid-IR SC output is 17%. It is, to the best of our knowledge, the highest average power mid-IR SC generation in a ZBLAN fiber to date. In addition, a noise-like fiber oscillator based on a nonlinear loop mirror (NOLM) with wavepacket width of ~1.4 ns and repetition rate of 3.36 MHz at 1966 nm is also used as a seed of the MOPA for mid-IR SC generation in the ZBLAN fiber. At last, a mid-IR SC from 1.9 to beyond 3.6 μm with average output power of 14.3W, which is limited by injected noise-like pulses power, is generated. The optical-optical conversion efficiency from the 793 nm pump laser of the last stage TDFA to mid-IR SC output is 14.9%. This proves the amplified noise-like pulses are also appropriate for high power mid-IR SC generation in the ZBLAN fiber.

  15. Generation of coherent spin-wave modes in yttrium iron garnet microdiscs by spin–orbit torque

    PubMed Central

    Collet, M.; de Milly, X.; d'Allivy Kelly, O.; Naletov, V. V.; Bernard, R.; Bortolotti, P.; Ben Youssef, J.; Demidov, V. E.; Demokritov, S. O.; Prieto, J. L.; Muñoz, M.; Cros, V.; Anane, A.; de Loubens, G.; Klein, O.

    2016-01-01

    In recent years, spin–orbit effects have been widely used to produce and detect spin currents in spintronic devices. The peculiar symmetry of the spin Hall effect allows creation of a spin accumulation at the interface between a metal with strong spin–orbit interaction and a magnetic insulator, which can lead to a net pure spin current flowing from the metal into the insulator. This spin current applies a torque on the magnetization, which can eventually be driven into steady motion. Tailoring this experiment on extended films has proven to be elusive, probably due to mode competition. This requires the reduction of both the thickness and lateral size to reach full damping compensation. Here we show clear evidence of coherent spin–orbit torque-induced auto-oscillation in micron-sized yttrium iron garnet discs of thickness 20 nm. Our results emphasize the key role of quasi-degenerate spin-wave modes, which increase the threshold current. PMID:26815737

  16. Distributed fiber-optic laser-ultrasound generation based on ghost-mode of tilted fiber Bragg gratings.

    PubMed

    Tian, Jiajun; Zhang, Qi; Han, Ming

    2013-03-11

    Active ultrasonic testing is widely used for medical diagnosis, material characterization and structural health monitoring. Ultrasonic transducer is a key component in active ultrasonic testing. Due to their many advantages such as small size, light weight, and immunity to electromagnetic interference, fiber-optic ultrasonic transducers are particularly attractive for permanent, embedded applications in active ultrasonic testing for structural health monitoring. However, current fiber-optic transducers only allow effective ultrasound generation at a single location of the fiber end. Here we demonstrate a fiber-optic device that can effectively generate ultrasound at multiple, selected locations along a fiber in a controllable manner based on a smart light tapping scheme that only taps out the light of a particular wavelength for laser-ultrasound generation and allow light of longer wavelengths pass by without loss. Such a scheme may also find applications in remote fiber-optic device tuning and quasi-distributed biochemical fiber-optic sensing.

  17. Experimental investigation in transmission performance of polarization-entangled photon-pairs generated by cascaded χ(2) processes over standard single-mode optical fibers.

    PubMed

    Arahira, Shin; Murai, Hitoshi

    2012-07-02

    In this paper we report experimental investigation in transmission performance over standard single-mode optical fibers (SMFs) of polarization-entangled photon-pairs in a 1.5-μm band generated by cascaded second-harmonic generation and spontaneous parametric down conversion (c-SHG/SPDC) from a periodically poled LiNbO(3) (PPLN) ridge-waveguide device. Clear two-photon interference fringes were observed even after the transmission over 140 km of the SMF spools, remaining small degradation in the visibilities of less than 3%. The performance was also investigated by using optical attenuators, instead of the SMF spools, to study the maximum reach of the distribution of the entanglement in terms of loss penalty. The results show that the quantum entanglement could be distributed even with 50 dB of the transmission loss with violation of Bell inequality by using the c-SHG/SPDC-based photon-pair source.

  18. Consideration of coordinated solar tracking of an array of compact solar-pumped lasers combined with photovoltaic cells for electricity generation

    NASA Astrophysics Data System (ADS)

    Motohiro, Tomoyoshi; Ichiki, Akihisa; Ichikawa, Tadashi; Ito, Hiroshi; Hasegawa, Kazuo; Mizuno, Shintaro; Ito, Tadashi; Kajino, Tsutomu; Takeda, Yasuhiko; Higuchi, Kazuo

    2015-08-01

    A monochromatic laser light with a photon energy just above the band edge of photovoltaic cells can be converted into electricity with minimal thermal loss. To attain efficient conversion of sunlight to laser light, a coordinated solar tracking system for an array of originally designed compact solar-pumped lasers of 50 mm aperture diameter is being constructed. As for the feasibility of this system, a prototype with a holding capacity of 25 compact solar-pumped lasers has been fabricated. The primary requisite of this system is that the angular accuracy of tracking should be below 1 mrad for all 25 compact solar-pumped lasers to sustain their continuous lasing. To realize this, imperative challenges have been elucidated including thermal expansion under sunlight. A prototype fabricated with its main frame made of Super Invar alloy was found to fulfill the requisite by measurement using a three-dimensional coordinate measuring machine.

  19. Operation of High-Voltage Transverse Shock Wave Ferromagnetic Generator in the Open Circuit and Charging Modes

    DTIC Science & Technology

    2005-06-01

    FMGs are based on the transverse (when the shock wave propagates across the magnetization vector M) shock demagnetization of Nd2Fe14B hard...generators based on the transverse (when the shock wave propagates across the magnetization vector M) shock wave demagnetization of Nd2Fe14B hard...and photo of a high-voltage transverse FMG are shown in Fig. 1. It contains a hollow hard ferromagnetic cylindrical Nd2Fe14B energy-carrying

  20. A Fast Response Mechanism for Insulin Storage in Crystals May Involve a Novel Mode of Kink Generation

    NASA Astrophysics Data System (ADS)

    Vekilov, Peter

    2010-03-01

    Crystals, likely rhombohedral, of Zn-insulin hexamers form in the islets of Langerhans in the pancreases of many mammals. The suggested function of crystal formation is to protect the insulin from proteases and increase the degree of conversion of soluble proinsulin. To accomplish this, crystal growth should be fast and adaptable to rate fluctuations in the conversion reaction. Zn-insulin crystals grow layer-by-layer. Each layer spreads by the attachment of molecules to kinks located at the layers' edges, also called steps. The kinks are thought to be generated either by thermal fluctuations, as postulated by Gibbs, or by one-dimensional nucleation of new crystalline rows. The kink density determines the rate at which steps advance, and these two kink-generation mechanisms lead to weak near-linear responses of the growth rate to concentration variations. We demonstrate for the crystallization of Zn-insulin a novel mechanism of kink generation, whereby 2D clusters of several insulin molecules pre-formed on the terraces between steps associate to the steps. This mechanism results in several-fold higher kink density, faster rate of crystallization, and a high sensitivity of the kinetics to small increases of the solute concentration. If the found mechanism operates during insulin crystallization in vivo, it could be a part of the biological regulation of insulin production and function. For other crystallizing materials in biological and non-biological systems, this mechanism provides an understanding of the often seen non-linear acceleration of the kinetics.

  1. Effects of cyclic impacts on the performance of a piezo-composite electricity generating element in a d33 mode energy harvesting.

    PubMed

    Pham, Van Lai; Ha, Ngoc San; Goo, Nam Seo; Choo, Jinkyo F

    2014-10-01

    The increasing use of piezoelectric generators to harvest energy from various ambient sources requires the establishment of durability data for piezoelectric materials. In this paper, a d3 mode piezocomposite electricity generating element (PCGE) was tested for its durability under cyclic impact loading. For this purpose, a motor driven lever system was designed to apply constant impact force on PCGEs. To investigate the durability of PCGEs, the output voltage of the PCGEs was observed upon repeated application of an impact force until eventual loss of the generated voltage. The experimental results enabled to determine the number of cycles until which PCGEs can be used without loss of their electricity generation performance with respect to the stress level applied on the PCGEs. At low stress level (around 0.76 MPa or lower), the PCGE showed almost insignificant degradation even after 2 million cycles whereas degradation occurred sooner (after 8 x 10(5) cycles) at higher stress levels (around 0.92 MPa or higher). The effects of impact loading on the durability of the PCGEs were also examined by X-ray photographs of the specimens.

  2. Stable dual-wavelength single-longitudinal-mode ring erbium-doped fiber laser for optical generation of microwave frequency

    NASA Astrophysics Data System (ADS)

    Wang, T.; Liang, G.; Miao, X.; Zhou, X.; Li, Q.

    2012-05-01

    We demonstrate a simple dual-wavelength ring erbium-doped fiber laser operating in single-longitudinal-mode (SLM) at room temperature. A pair of reflection type short-period fiber Bragg gratings (FBGs), which have two different center wavelengths of 1545.072 and 1545.284 nm, are used as the wavelength-selective component of the laser. A segment of unpumped polarization maintaining erbium-doped fiber (PM-EDF) is acted as a narrow multiband filter. By turning the polarization controller (PC) to enhance the polarization hole burning (PHB), the single-wavelength and dual-wavelength laser oscillations are observed at 1545.072 and 1545.284 nm. The output power variation is less than 0.6 dB for both wavelengths over a five-minute period and the optical signal to noise ratio (OSNR) is greater than 50 dB. By beating the dual-wavelengths at a photodetector (PD), a microwave signal at 26.44 GHz is demonstrated.

  3. Satellite Coordination

    NASA Astrophysics Data System (ADS)

    Cohen, R. J.

    2004-06-01

    The Radio Regulations set out complex procedures to ensure that when new systems start to use the frequency bands allocated to them there is minimal disruption to existing systems using the same bands. The process of satellite coordination is described, and the issues for radio astronomy are discussed. In order to be protected by the ITU-R machinery radio telescopes need to be officially registered. The issue of paper satellites highlights the need for early registration to gain priority over incoming systems. Modern developments including the use of complex Monte-Carlo simulations to predict interference levels, and the issue of adjacent band interference, are discussed.

  4. Double-Wall Carbon Nanotube Hybrid Mode-Locker in Tm-doped Fibre Laser: A Novel Mechanism for Robust Bound-State Solitons Generation

    NASA Astrophysics Data System (ADS)

    Chernysheva, Maria; Bednyakova, Anastasia; Al Araimi, Mohammed; Howe, Richard C. T.; Hu, Guohua; Hasan, Tawfique; Gambetta, Alessio; Galzerano, Gianluca; Rümmeli, Mark; Rozhin, Aleksey

    2017-03-01

    The complex nonlinear dynamics of mode-locked fibre lasers, including a broad variety of dissipative structures and self-organization effects, have drawn significant research interest. Around the 2 μm band, conventional saturable absorbers (SAs) possess small modulation depth and slow relaxation time and, therefore, are incapable of ensuring complex inter-pulse dynamics and bound-state soliton generation. We present observation of multi-soliton complex generation in mode-locked thulium (Tm)-doped fibre laser, using double-wall carbon nanotubes (DWNT-SA) and nonlinear polarisation evolution (NPE). The rigid structure of DWNTs ensures high modulation depth (64%), fast relaxation (1.25 ps) and high thermal damage threshold. This enables formation of 560-fs soliton pulses; two-soliton bound-state with 560 fs pulse duration and 1.37 ps separation; and singlet+doublet soliton structures with 1.8 ps duration and 6 ps separation. Numerical simulations based on the vectorial nonlinear Schr¨odinger equation demonstrate a transition from single-pulse to two-soliton bound-states generation. The results imply that DWNTs are an excellent SA for the formation of steady single- and multi-soliton structures around 2 μm region, which could not be supported by single-wall carbon nanotubes (SWNTs). The combination of the potential bandwidth resource around 2 μm with the soliton molecule concept for encoding two bits of data per clock period opens exciting opportunities for data-carrying capacity enhancement.

  5. Double-Wall Carbon Nanotube Hybrid Mode-Locker in Tm-doped Fibre Laser: A Novel Mechanism for Robust Bound-State Solitons Generation

    PubMed Central

    Chernysheva, Maria; Bednyakova, Anastasia; Al Araimi, Mohammed; Howe, Richard C. T.; Hu, Guohua; Hasan, Tawfique; Gambetta, Alessio; Galzerano, Gianluca; Rümmeli, Mark; Rozhin, Aleksey

    2017-01-01

    The complex nonlinear dynamics of mode-locked fibre lasers, including a broad variety of dissipative structures and self-organization effects, have drawn significant research interest. Around the 2 μm band, conventional saturable absorbers (SAs) possess small modulation depth and slow relaxation time and, therefore, are incapable of ensuring complex inter-pulse dynamics and bound-state soliton generation. We present observation of multi-soliton complex generation in mode-locked thulium (Tm)-doped fibre laser, using double-wall carbon nanotubes (DWNT-SA) and nonlinear polarisation evolution (NPE). The rigid structure of DWNTs ensures high modulation depth (64%), fast relaxation (1.25 ps) and high thermal damage threshold. This enables formation of 560-fs soliton pulses; two-soliton bound-state with 560 fs pulse duration and 1.37 ps separation; and singlet+doublet soliton structures with 1.8 ps duration and 6 ps separation. Numerical simulations based on the vectorial nonlinear Schr¨odinger equation demonstrate a transition from single-pulse to two-soliton bound-states generation. The results imply that DWNTs are an excellent SA for the formation of steady single- and multi-soliton structures around 2 μm region, which could not be supported by single-wall carbon nanotubes (SWNTs). The combination of the potential bandwidth resource around 2 μm with the soliton molecule concept for encoding two bits of data per clock period opens exciting opportunities for data-carrying capacity enhancement. PMID:28287159

  6. Double-Wall Carbon Nanotube Hybrid Mode-Locker in Tm-doped Fibre Laser: A Novel Mechanism for Robust Bound-State Solitons Generation.

    PubMed

    Chernysheva, Maria; Bednyakova, Anastasia; Al Araimi, Mohammed; Howe, Richard C T; Hu, Guohua; Hasan, Tawfique; Gambetta, Alessio; Galzerano, Gianluca; Rümmeli, Mark; Rozhin, Aleksey

    2017-03-13

    The complex nonlinear dynamics of mode-locked fibre lasers, including a broad variety of dissipative structures and self-organization effects, have drawn significant research interest. Around the 2 μm band, conventional saturable absorbers (SAs) possess small modulation depth and slow relaxation time and, therefore, are incapable of ensuring complex inter-pulse dynamics and bound-state soliton generation. We present observation of multi-soliton complex generation in mode-locked thulium (Tm)-doped fibre laser, using double-wall carbon nanotubes (DWNT-SA) and nonlinear polarisation evolution (NPE). The rigid structure of DWNTs ensures high modulation depth (64%), fast relaxation (1.25 ps) and high thermal damage threshold. This enables formation of 560-fs soliton pulses; two-soliton bound-state with 560 fs pulse duration and 1.37 ps separation; and singlet+doublet soliton structures with 1.8 ps duration and 6 ps separation. Numerical simulations based on the vectorial nonlinear Schr¨odinger equation demonstrate a transition from single-pulse to two-soliton bound-states generation. The results imply that DWNTs are an excellent SA for the formation of steady single- and multi-soliton structures around 2 μm region, which could not be supported by single-wall carbon nanotubes (SWNTs). The combination of the potential bandwidth resource around 2 μm with the soliton molecule concept for encoding two bits of data per clock period opens exciting opportunities for data-carrying capacity enhancement.

  7. Acoustic waves generated from seismic surface waves: propagation properties determined from Doppler sounding observations and normal-mode modelling

    NASA Astrophysics Data System (ADS)

    Artru, Juliette; Farges, Thomas; Lognonné, Philippe

    2004-09-01

    Since 1960, experiments have shown that perturbations of the ionosphere can occur after earthquakes, by way of dynamic coupling between seismic surface waves and the atmosphere. The atmospheric wave is amplified exponentially while propagating upwards due to the decrease of density, and interaction with the ionospheric plasma leads to clearly identified signals on both ground-based or satellite ionospheric measurements. In 1999 and 2000, after an upgrade of the HF Doppler sounder, the Commisariat à l'Énergie Atomique systematically recorded these effects in the ionosphere with the Francourville (France) network, by measuring vertical oscillations of ionospheric layers with the Doppler technique. Normal-mode theory extended to a solid Earth with an atmosphere allows successful modelling of such signals, even if this 1-D approach is probably too crude, especially in the solid Earth, where 20 s surface waves see large lateral variations in the crust. The combination of observations and simulations provides a new tool to determine acoustic gravity wave propagation characteristics from the ground to ionospheric height. Observed velocity and amplification of the atmospheric waves show good agreement from the ground up to moderate sounding altitudes (140-150 km); however, at higher altitudes the propagation speed is found to be much smaller than predicted and attenuation is underestimated. This shows that the standard formalism of acoustic gravity waves in the atmosphere cannot efficiently describe propagation in the ionized atmosphere. Further work is needed to characterize the propagation of acoustic waves in this altitude range: we believe that seismic waves can provide a well-constrained source for such study.

  8. In situ ligand generation for novel Mn(II) and Ni(II) coordination polymers with disulfide ligand: Solvothermal syntheses, structures and magnetic properties

    SciTech Connect

    Han, Yinfeng Wang, Chang'an; Zheng, Zebao; Sun, Jiafeng; Nie, Kun; Zuo, Jian; Zhang, Jianping

    2015-07-15

    Two coordination polymers, ([Mn{sub 2}(L1){sub 2}(μ{sub 2}-H{sub 2}O)(H{sub 2}O){sub 4}]·5H{sub 2}O){sub n}1 and ([Ni(L1)(H{sub 2}O){sub 2}]·2H{sub 2}O){sub n}2 (H{sub 2}L1=2,2′-dithiobisnicotinic acid), were prepared by the solvothermal reactions of the Mn(II) or Ni(II) ions with 2-mercaptonanicotinic acid. In 1, the [Mn{sub 2}(COO){sub 4}] units are connected by the 2,2′-dithiobisnicotinic dianion to form a two-dimensional (4,4)-connected network. In 2, the adjacent Ni(II) ions are connected by the carboxyl groups of the 2,2′-dithiobisnicotinic dianion to form an one-dimensional inorganic rod-shaped chain [Ni(COO){sub 2}]{sub n}, which are further interconnected by the 2,2′-dithiobisnicotinic ligand, giving rise to a two-dimensional framework. Variable-temperature magnetic susceptibilities of 1 and 2 exhibit overall weak antiferromagnetic coupling between the adjacent metal ions. - Graphical abstract: Two 2D coordination polymers were synthesized by transition-metal/in-situ oxidation of 2-mercaptonicotinic acid. The compounds pack into 2D frameworks by the carboxyl groups of 2,2′-dithiobisnicotinic dianion and exhibit overall weak antiferromagnetic coupling. - Highlights: • Two 2D coordination polymers containing 2,2′-dithiobisnicotinic dianion. • In situ oxidation and dehydro coupling reaction of 2-mercaptonbenzoic acid. • Two compounds display weak antiferromagnetic exchanges.

  9. Stable Similariton Generation in an All-Fiber Hybrid Mode-Locked Ring Laser for Frequency Metrology.

    PubMed

    Lazarev, Vladimir; Krylov, Alexander; Dvoretskiy, Dmitriy; Sazonkin, Stanislav; Pnev, Alexey; Leonov, Stanislav; Shelestov, Dmitriy; Tarabrin, Mikhail; Karasik, Valeriy; Kireev, Alexey; Gubin, Mikhail

    2016-07-01

    Ultrashort pulse lasers constitute an important tool in the emerging field of optical frequency metrology and are enabling unprecedented measurement capabilities and new applications in a wide range of fields, including precision spectroscopy, atomic clocks, ultracold gases, and molecular fingerprinting. We demonstrate the generation of stable 127-fs self-similar pulses at a central wavelength of 1560 nm with 7.14-mW average output power. Similariton lasers have a low repetition rate deviation in the averaging time interval [Formula: see text], a low relative intensity noise [Formula: see text] (30 Hz to 10 kHz), a narrow single comb line width of 32 kHz, and high reliability. Thus, such lasers are highly promising for further development of the stabilized combs and open up a robust and substantially simplified route to synthesizing low-noise microwaves.

  10. Numerical Grid Generation. Proceedings of a Symposium on the Numerical Generation of Curvilinear Coordinate Systems and their Use in the Numerical Solution of Partial Differential Equations, held April 1982, Nashville, Tennessee

    DTIC Science & Technology

    1982-04-01

    to a line on which the coordinate &i is constant. Base vectors, tangents, normals, area, and volume To establish the terminology , consider the...Cauchy-Diemann prohlem is not known it is convenient to r~ner (5) and (7) into more standart form, namely: (8) -f(x’y) H - + =f(X,v)H nx () ffy1 2 av

  11. Research on the dq coordinate transform in the six-phase double star windings shifted by 30° synchronous generators with axial magnetic field

    NASA Astrophysics Data System (ADS)

    Bian, Xiangnan; Ma, Qishuang

    2006-11-01

    As an intermediate frequency power source, the double star windings shifted by 30° synchronous generator with axial magnetic field (DSWAMF) is widely used in the different areas. Using the generalized inverse, the transformation matrix of double windings synchronous generators with two Y-connected 3-phase symmetrical windings displaced in turn by 30° from rotating to stationary axes is proposed. With the transformation matrix, the state-space model of the generators is established. Obtained the relation of interconnection, and optimize the parameter. The kind of machine is simulated by finite element method (FEM), mutual inductance of the simulation is similar to theory. The generator mathematical model is established, the internal parameter of this kind of generator can be obtained easily with transformation matrix.

  12. Propagating Waves of Directionality and Coordination Orchestrate Collective Cell Migration

    PubMed Central

    Zaritsky, Assaf; Kaplan, Doron; Hecht, Inbal; Natan, Sari; Wolf, Lior; Gov, Nir S.; Ben-Jacob, Eshel; Tsarfaty, Ilan

    2014-01-01

    The ability of cells to coordinately migrate in groups is crucial to enable them to travel long distances during embryonic development, wound healing and tumorigenesis, but the fundamental mechanisms underlying intercellular coordination during collective cell migration remain elusive despite considerable research efforts. A novel analytical framework is introduced here to explicitly detect and quantify cell clusters that move coordinately in a monolayer. The analysis combines and associates vast amount of spatiotemporal data across multiple experiments into transparent quantitative measures to report the emergence of new modes of organized behavior during collective migration of tumor and epithelial cells in wound healing assays. First, we discovered the emergence of a wave of coordinated migration propagating backward from the wound front, which reflects formation of clusters of coordinately migrating cells that are generated further away from the wound edge and disintegrate close to the advancing front. This wave emerges in both normal and tumor cells, and is amplified by Met activation with hepatocyte growth factor/scatter factor. Second, Met activation was found to induce coinciding waves of cellular acceleration and stretching, which in turn trigger the emergence of a backward propagating wave of directional migration with about an hour phase lag. Assessments of the relations between the waves revealed that amplified coordinated migration is associated with the emergence of directional migration. Taken together, our data and simplified modeling-based assessments suggest that increased velocity leads to enhanced coordination: higher motility arises due to acceleration and stretching that seems to increase directionality by temporarily diminishing the velocity components orthogonal to the direction defined by the monolayer geometry. Spatial and temporal accumulation of directionality thus defines coordination. The findings offer new insight and suggest a basic

  13. Formation of adherens and communicating junctions coordinate the differentiation of the shedding-layer and beta-epidermal generation in regenerating lizard epidermis.

    PubMed

    Alibardi, Lorenzo

    2014-06-01

    In the lizard epidermis, the formation of a stratified alpha- and beta-layer, separated by a shedding complex for molting, suggests that keratinocytes communicate in a coordinated manner after they leave the basal layers during the shedding cycle. I have therefore studied the localization of cell junctional proteins such as beta-catenin and connexins 43 and 26 during scale regeneration in lizard using immunocytochemistry. Beta-catenin is also detected in nuclei of basal cells destined to give rise to the Oberhäutchen and beta-cells suggesting activation of the Wnt-pathway during beta-cell differentiation. The observations show that cells of the entire shedding layer (clear and Oberhäutchen) and beta-layer are connected by beta-catenin (adherens junctions) and connexins (communicating junctions) during their differentiation. This likely cell coupling determines the formation of a distinct shedding and beta-layer within the regenerating epidermis. The observed pattern of cell junctional stratification suggests that after departing from the basal layer Oberhäutchen and beta-cells form a continuous communicating compartment that coordinates the contemporaneous differentiation along the entire scale. While the beta-layer matures the junctions are lost while other cell junctions are formed in the following mesos- and alpha-cell layers. This process determines the formation of layers with different texture (harder or softer) and the precise localization of the shedding layer within lizard epidermis.

  14. Conformal Fermi Coordinates

    SciTech Connect

    Dai, Liang; Pajer, Enrico; Schmidt, Fabian E-mail: Enrico.pajer@gmail.com

    2015-11-01

    Fermi Normal Coordinates (FNC) are a useful frame for isolating the locally observable, physical effects of a long-wavelength spacetime perturbation. Their cosmological application, however, is hampered by the fact that they are only valid on scales much smaller than the horizon. We introduce a generalization that we call Conformal Fermi Coordinates (CFC). CFC preserve all the advantages of FNC, but in addition are valid outside the horizon. They allow us to calculate the coupling of long- and short-wavelength modes on all scales larger than the sound horizon of the cosmological fluid, starting from the epoch of inflation until today, by removing the complications of the second order Einstein equations to a large extent, and eliminating all gauge ambiguities. As an application, we present a calculation of the effect of long-wavelength tensor modes on small scale density fluctuations. We recover previous results, but clarify the physical content of the individual contributions in terms of locally measurable effects and ''projection'' terms.

  15. N-H stretching modes around 3300 wavenumber from peptide backbones observed by chiral sum frequency generation vibrational spectroscopy.

    PubMed

    Fu, Li; Wang, Zhuguang; Yan, Elsa C Y

    2014-09-01

    We present a detailed analysis of the molecular origin of the chiral sum frequency generation (SFG) signals of proteins and peptides at interfaces in the N-H stretching vibrational region. The N-H stretching can be a probe for investigating structural and functional properties of proteins, but remains technically difficult to analyze due to the overlapping with the O-H stretching of water molecules. Chiral SFG spectroscopy offers unique tools to study the N-H stretching from proteins at interfaces without interference from the water background. However, the molecular origin of the N-H stretching signals of proteins is still unclear. This work provides a justification of the origin of chiral N-H signals by analyzing the vibrational frequencies, examining chiral SFG theory, studying proton (hydrogen/deuterium) exchange kinetics, and performing optical control experiments. The results demonstrate that the chiral N-H stretching signals at ~3300 cm(-1) originate from the amide group of the protein backbones. This chiral N-H stretching signal offers an in situ, real-time, and background-free probe for interrogating the protein structures and dynamics at interfaces at the molecular level.

  16. A new optical parametric amplifier based on lithium thioindate used for sum frequency generation vibrational spectroscopic studies of the amide I mode of an interfacial model peptide.

    PubMed

    York, Roger L; Holinga, George J; Guyer, Dean R; McCrea, Keith R; Ward, Robert S; Somorjai, Gabor A

    2008-09-01

    We describe a new optical parametric amplifier (OPA) that employs lithium thioindate, LiInS2 (LIS), to create tunable infrared light between 1500 cm(-1) and 2000 cm(-1). The OPA based on LIS described within provides intense infrared light with a good beam profile relative to similar OPAs built on silver gallium sulfide, AgGaS2 (AGS), or silver gallium selenide, AgGaSe2 (AGSe). We have used the new LIS OPA to perform surface-specific sum frequency generation (SFG) vibrational spectroscopy of the amide I vibrational mode of a model peptide at the hydrophobic deuterated polystyrene (d8-PS)-phosphate buffered saline interface. This model polypeptide (which is known to be an alpha-helix in the bulk solution under the high ionic strength conditions employed here) contains hydrophobic leucyl (L) residues and hydrophilic lysyl (K) residues, with sequence Ac-LKKLLKLLKKLLKL-NH2. The amide I mode at the d8-PS-buffer interface was found to be centered around 1655 cm(-1). This can be interpreted as the peptide having maintained its alpha-helical structure when adsorbed on the hydrophobic surface, although other interpretations are discussed.

  17. A new optical parametric amplifier based on lithium thioindate used for sum frequency generation vibrational spectroscopic studies of the Amide I mode of an interfacial model peptide

    SciTech Connect

    York, Roger L.; Holinga, George J.; Guyer, Dean R.; McCrea, Keith R.; Ward, Robert S.; Somorjai, Gabor A.

    2008-05-03

    We describe a new optical parametric amplifier (OPA) that employs lithium thioindate, LiInS{sub 2} (LIS), to create tunable infrared light between 1500 cm{sup -1} and 2000 cm{sup -1}. The OPA based on LIS described within provides intense infrared light with a good beam profile relative to similar OPAs built on silver gallium sulfide, AgGaS{sub 2} (AGS), or silver gallium selenide, AgGaSe{sub 2} (AGSe). We have used the new LIS OPA to perform surface-specific sum frequency generation (SFG) vibrational spectroscopy of the amide I vibrational mode of a model peptide at the hydrophobic deuterated polystyrene (d{sub 8}-PS)-phosphate buffered saline interface. This model polypeptide (which is known to be an ?-helix in the bulk solution under the high ionic strength conditions employed here) contains hydrophobic leucyl (L) residues and hydrophilic lysyl (K) residues, with sequence Ac-LKKLLKLLKKLLKL-NH{sub 2}. The amide I mode at the d{sub 8}-PS-buffer interface was found to be centered around 1655 cm{sup -1}. This can be interpreted as the peptide having maintained its {alpha}-helical structure when adsorbed on the hydrophobic surface, although other interpretations are discussed.

  18. Optical frequency comb generator based on a monolithically integrated passive mode-locked ring laser with a Mach-Zehnder interferometer.

    PubMed

    Corral, V; Guzmán, R; Gordón, C; Leijtens, X J M; Carpintero, G

    2016-05-01

    We report the demonstration of an optical-frequency comb generator based on a monolithically integrated ring laser fabricated in a multiproject wafer run in an active/passive integration process in a generic foundry using standardized building blocks. The device is based on a passive mode-locked ring laser architecture, which includes a Mach-Zehnder interferometer to flatten the spectral shape of the comb output. This structure allows monolithic integration with other optical components, such as optical filters for wavelength selection, or dual wavelength lasers for their stabilization. The results show a -10  dB span of the optical comb of 8.7 nm (1.08 THz), with comb spacing of 10.16 GHz. We also obtain a flatness of 44 lines within a 1.8 dB power variation.

  19. Fiber-based multiple-beam reflection interferometer for single-longitudinal-mode generation in fiber laser based on semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Terentyev, V. S.; Simonov, V. A.; Babin, S. A.

    2017-02-01

    A technique of single-longitudinal-mode selection in a fiber laser by means of a fiber multiple-beam reflection interferometer (FRI) has been experimentally demonstrated for the first time. The laser is based on a semiconductor optical amplifier placed in a linear fiber cavity formed by a fiber Bragg grating (FBG), and the FRI generates at 1529.24 nm with output power of 1 mW in single-frequency regime with a linewidth of about 217 kHz and polarization extinction ratio of  >30 dB. The FRI technique potentially enables fast tuning (within the FBG bandwidth of ~0.9 nm in our case) by varying the base length of the FRI that can be used in a number of practical applications.

  20. Generation regimes of bidirectional hybridly mode-locked ultrashort pulse erbium-doped all-fiber ring laser with a distributed polarizer.

    PubMed

    Krylov, Alexander A; Chernykh, Dmitriy S; Arutyunyan, Natalia R; Grebenyukov, Vyacheslav V; Pozharov, Anatoly S; Obraztsova, Elena D

    2016-05-20

    We report on the stable picosecond and femtosecond pulse generation from the bidirectional erbium-doped all-fiber ring laser hybridly mode-locked with a coaction of a single-walled carbon nanotube-based saturable absorber and nonlinear polarization evolution that was introduced through the insertion of the short-segment polarizing fiber. Depending on the total intracavity dispersion value, the laser emits conservative solitons, transform-limited Gaussian pulses, or highly chirped stretched pulses with almost 20 nm wide parabolic spectrum in both clockwise (CW) and counterclockwise (CCW) directions of the ring. Owing to the polarizing action in the cavity, we have demonstrated for the first time, to the best of our knowledge, an efficient tuning of soliton pulse characteristics for both CW and CCW channels via an appropriate polarization control. We believe that the bidirectional laser presented may be highly promising for gyroscopic and other dual-channel applications.

  1. Multi-Generational Kinship, Multiple Mating, and Flexible Modes of Parental Care in a Breeding Population of the Veery (Catharus fuscescens), a Trans-Hemispheric Migratory Songbird.

    PubMed

    Halley, Matthew R; Heckscher, Christopher M; Kalavacharla, Venugopal

    2016-01-01

    We discovered variable modes of parental care in a breeding population of color-banded Veeries (Catharus fuscescens), a Nearctic-Neotropical migratory songbird, long thought to be socially monogamous, and performed a multi-locus DNA microsatellite analysis to estimate parentage and kinship in a sample of 37 adults and 21 offspring. We detected multiple mating in both sexes, and four modes of parental care that varied in frequency within and between years including multiple male feeders at some nests, and males attending multiple nests in the same season, each with a different female. Unlike other polygynandrous systems, genetic evidence indicates that multi-generational patterns of kinship occur among adult Veeries at our study site, and this was corroborated by the capture of an adult male in 2013 that had been banded as a nestling in 2011 at a nest attended by multiple male feeders. All genotyped adults (n = 37) were related to at least one other bird in the sample at the cousin level or greater (r ≥ 0.125), and 81% were related to at least one other bird at the half-sibling level or greater (r ≥ 0.25, range 0.25-0.60). Although our sample size is small, it appears that the kin structure is maintained by natal philopatry in both sexes, and that Veeries avoid mating with close genetic kin. At nests where all adult feeders were genotyped (n = 9), the male(s) were unrelated to the female (mean r = -0.11 ± 0.15), whereas genetic data suggest close kinship (r = 0.254) between two male co-feeders at the nests of two females in 2011, and among three of four females that were mated to the same polygynous male in 2012. To our knowledge, this is the first evidence of polygynandry occurring among multiple generations of close genetic kin on the breeding ground of a Nearctic-Neotropical migratory songbird.

  2. Multi-Generational Kinship, Multiple Mating, and Flexible Modes of Parental Care in a Breeding Population of the Veery (Catharus fuscescens), a Trans-Hemispheric Migratory Songbird

    PubMed Central

    Kalavacharla, Venugopal

    2016-01-01

    We discovered variable modes of parental care in a breeding population of color-banded Veeries (Catharus fuscescens), a Nearctic-Neotropical migratory songbird, long thought to be socially monogamous, and performed a multi-locus DNA microsatellite analysis to estimate parentage and kinship in a sample of 37 adults and 21 offspring. We detected multiple mating in both sexes, and four modes of parental care that varied in frequency within and between years including multiple male feeders at some nests, and males attending multiple nests in the same season, each with a different female. Unlike other polygynandrous systems, genetic evidence indicates that multi-generational patterns of kinship occur among adult Veeries at our study site, and this was corroborated by the capture of an adult male in 2013 that had been banded as a nestling in 2011 at a nest attended by multiple male feeders. All genotyped adults (n = 37) were related to at least one other bird in the sample at the cousin level or greater (r ≥ 0.125), and 81% were related to at least one other bird at the half-sibling level or greater (r ≥ 0.25, range 0.25–0.60). Although our sample size is small, it appears that the kin structure is maintained by natal philopatry in both sexes, and that Veeries avoid mating with close genetic kin. At nests where all adult feeders were genotyped (n = 9), the male(s) were unrelated to the female (mean r = -0.11 ± 0.15), whereas genetic data suggest close kinship (r = 0.254) between two male co-feeders at the nests of two females in 2011, and among three of four females that were mated to the same polygynous male in 2012. To our knowledge, this is the first evidence of polygynandry occurring among multiple generations of close genetic kin on the breeding ground of a Nearctic-Neotropical migratory songbird. PMID:27331399

  3. Self-consistent simulation of an electron beam for a new autoresonant x-ray generator based on TE 102 rectangular mode

    NASA Astrophysics Data System (ADS)

    Dugar-Zhabon, V. D.; Orozco, E. A.; Herrera, A. M.

    2016-02-01

    The space cyclotron autoresonance interaction of an electron beam with microwaves of TE 102 rectangular mode is simulated. It is shown that in these conditions the beam electrons can achieve energies which are sufficient to generate hard x-rays. The physical model consists of a rectangular cavity fed by a magnetron oscillator through a waveguide with a ferrite isolator, an iris window and a system of dc current coils which generates an axially symmetric magnetic field. The 3D magnetic field profile is that which maintains the electron beam in the space autoresonance regime. To simulate the beam dynamics, a full self-consistent electromagnetic particle-in-cell code is developed. It is shown that the injected 12keV electron beam of 0.5A current is accelerated to energy of 225keV at a distance of an order of 17cm by 2.45GHz standing microwave field with amplitude of 14kV/cm.

  4. Complex coordinated extracellular metabolism: Acid phosphatases activate diluted human leukocyte proteins to generate energy flow as NADPH from purine nucleotide ribose

    PubMed Central

    Hibbs, John B.; Vavrin, Zdenek; Cox, James E.

    2016-01-01

    Complex metabolism is thought to occur exclusively in the crowded intracellular environment. Here we report that diluted enzymes from lysed human leukocytes produce extracellular energy. Our findings involve two pathways: the purine nucleotide catabolic pathway and the pentose phosphate pathway, which function together to generate energy as NADPH. Glucose6P fuel for NADPH production is generated from structural ribose of purine ribonucleoside monophosphates, ADP, and ADP-ribose. NADPH drives glutathione reductase to reduce an oxidized glutathione disulfide-glutathione redox couple. Acid phosphatases initiate ribose5P salvage from purine ribonucleoside monophosphates, and transaldolase controls the direction of carbon chain flow through the nonoxidative branch of the pentose phosphate pathway. These metabolic control points are regulated by pH. Biologically, this energy conserving metabolism could function in perturbed extracellular spaces. PMID:26895212

  5. Create powerful Broader Impact Tools and k-16 inquiry lessons aligned to next generation standards for this generation of science students by building a partnership between scientists and educational coordinators

    NASA Astrophysics Data System (ADS)

    Cohen, E.; Quan, T. M.

    2012-12-01

    A model of collaboration between research scientists, educational non-profit organizations and practicing classroom teachers will be explained. This method can provide a researcher with support providing educationally sound age appropriate science lessons while doing what they love most, researching! Appointing an educational coordinator to fulfill broader impacts may sound out of the ordinary, but evaluators recognize the important aspect of finding experts to support research in the Broader Impact, just as you would in the science part of the grant. By creating a team using experts in their field, the scientist can focus on the science while the broader Impacts will impact students and teachers. There was a team made out of experts, research, and data from the International Ocean Drilling Program, Oklahoma State University, Rutgers, and public school teachers. The educational coordinator aligns the high end scientific work to standards and benchmark for each group of students. Once the content is academically leveled at age appropriate readiness, successful lessons can be created. The scientists provide content and the non-profits provide facilitation and a way to implement the lessons created over a national scope.

  6. 3D Rare earth porous coordination frameworks with formamide generated in situ syntheses: Crystal structure and down- and up-conversion luminescence

    SciTech Connect

    Ma, Xue; Tian, Jing; Yang, Hong-Y.; Zhao, Kai; Li, Xia

    2013-05-01

    The reaction of RE(NO)₃·6H₂O and formamide yielded the coordination polymers, [RE(HCOO)₄]⁻[NH₂CHNH₂]⁺ (RE=Y 1, Eu 2, Gd 3, Tb 4, Dy 5, Er 6, and Yb 7). They possess 3D porous frameworks with the 1D rhombic channels occupied by [NH₂CHNH₂]⁺ cations. Complexes 2 and 4 display the characteristic down-conversion emissions corresponding to ⁵D₀→⁷FJ (J=1–4) transitions of Eu(III) ion and ⁵D₄→⁷FJ (J=6–3) transitions of Tb(III) ion, respectively. Longer lifetime values of 2.128±0.002 ms (⁵D₀) for 2 and 2.132±0.002 ms (⁵D₄) for 4 have been observed. The up-conversion spectra of the Y:Yb,Er and Gd:Yb,Er codoped complexes exhibit three emission bands around 410 (⁴H9/2→⁴I15/2, blue), 518–570 (⁴S3/2, ²H11/2→⁴I15/2, green), and 655 nm (⁴F9/2→⁴I15/2, red). - Graphical Abstract: The complexes [RE(HCOO)₄]⁻[NH₂CHNH₂]⁺ possess 3D porous frameworks. Eu(III) and Tb(III) complexes show characteristic emission of Ln(III) ions. The up-conversion emission of the Y:Yb,Er and Gd:Yb,Er codoped complexes was observed. Highlights: •The reaction of RE(NO)₃·6H₂O and formamide produced complexes [RE(HCOO)₄]⁻[NH₂CHNH₂]⁺. • The complexes possess 3D frameworks with the 1D channels occupied by [NH₂CHNH₂]+ cations. • Eu(III)/Tb(III) complexes display the characteristic down-conversion emission of Ln(III) ions. • The Y:Yb,Er and Gd:Yb,Er doped complexes exhibit the up-conversion emission.

  7. Ab initio molecular orbital configuration interaction study of Ni(PH sub 3 ) sub 2 (N sub 2 ). Differences in electron correlation effects between. eta. sup 1 -end-on and. eta. sup 2 -side-on N sub 2 coordination modes

    SciTech Connect

    Sakaki, Shigeyoshi; Ohkubo, Katsutoshi )

    1989-07-27

    Structure and bonding nature of Ni(PH{sub 3}){sub 2}({eta}{sup 1}-N{sub 2}), Ni(PH{sub 3}){sub 2}({eta}{sup 2}-N{sub 2}) ({eta}{sup 1}-N{sub 2} = {eta}-end-on N{sub 2}, {eta}{sup 2}-N{sub 2} = {eta}{sup 2}-N{sub 2} = {eta}{sup 2}-side-on N{sub 2}), and Ni(PH{sub 3}){sub 2}(C{sub 2}h{sub 4}) are studied with ab initio MO Moeller-Plesset (MP) perturbation and single-double configuration interaction (SD-CI) methods. Introduction of electron correlation effects is indispensable for investigating the relative stability of two coordination modes, {eta}{sup 1}-end-on and {eta}{sup 2}-side-on coordinations, of the N{sub 2} complex. Although the binding energies of both coordination modes are almost the same on the Hartree-Fock level, introducing electron correlation effects with MP2, MP4(DQ), MP4(SDQ), and SD-CI methods yield much larger binding energy of the {eta}{sup 1}-end-on N{sub 2} coordination than that of the {eta}{sup 2}-side-on N{sub 2} coordination. Electron correlation effects on the Ni-N{sub 2} distance are also noticeable; in the {eta}{sup 1}-end-on mode, the Ni-N{sub 2} distance shortens by about 0.1 {angstrom} upon introducing electron correlation effects with MP2, MP4, and SD-CI methods, and the resultant Ni-N{sub 2} distance agrees well with the experimental value. However, introducing electron correlation effects with the SD-CI method only slightly changes the Ni-N{sub 2} distance of Ni(PH{sub 3}){sub 2}({eta}{sup 2}-N{sub 2}) and slightly lengthens the Ni-C distance of Ni(PH{sub 3}){sub 2}(C{sub 2}H{sub 4}), whereas both Ni-N and Ni-C bonds significantly lengthen by about 0.2-0.3 {angstrom} upon MP2 and MP4 calculations. A comparison of the optimized Ni-C distance and the calculated binding energy of the {eta}{sup 1}-end-on N{sub 2} coordination with the experimental values suggests that the SD-CI method is more reliable than the MP method in these complexes.

  8. How Do Teachers Coordinate Their Work? A Framing Approach

    ERIC Educational Resources Information Center

    Dumay, Xavier

    2014-01-01

    Since the 1970s, schools have been characterized as loosely coupled systems, meaning that the teachers' work is weakly coordinated at the local level. Nonetheless, few studies have focused on the local variations of coordination modes, their sources and their nature. In this article, the process of local coordination of the teachers' work is…

  9. Automatic determination of important mode-mode correlations in many-mode vibrational wave functions.

    PubMed

    König, Carolin; Christiansen, Ove

    2015-04-14

    We introduce new automatic procedures for parameterizing vibrational coupled cluster (VCC) and vibrational configuration interaction wave functions. Importance measures for individual mode combinations in the wave function are derived based on upper bounds to Hamiltonian matrix elements and/or the size of perturbative corrections derived in the framework of VCC. With a threshold, this enables an automatic, system-adapted way of choosing which mode-mode correlations are explicitly parameterized in the many-mode wave function. The effect of different importance measures and thresholds is investigated for zero-point energies and infrared spectra for formaldehyde and furan. Furthermore, the direct link between important mode-mode correlations and coordinates is illustrated employing water clusters as examples: Using optimized coordinates, a larger number of mode combinations can be neglected in the correlated many-mode vibrational wave function than with normal coordinates for the same accuracy. Moreover, the fraction of important mode-mode correlations compared to the total number of correlations decreases with system size. This underlines the potential gain in efficiency when using optimized coordinates in combination with a flexible scheme for choosing the mode-mode correlations included in the parameterization of the correlated many-mode vibrational wave function. All in all, it is found that the introduced schemes for parameterizing correlated many-mode vibrational wave functions lead to at least as systematic and accurate calculations as those using more standard and straightforward excitation level definitions. This new way of defining approximate calculations offers potential for future calculations on larger systems.

  10. The study of multireactional electrochemical interfaces via a tip generation/substrate collection mode of scanning electrochemical microscopy: the hydrogen evolution reaction for Mn in acidic solution.

    PubMed

    Leonard, Kevin C; Bard, Allen J

    2013-10-23

    We report a new method of scanning electrochemical microscopy (SECM) that can be used to separate multireactional electrochemical interfaces, i.e., electrodes at which two or more reactions occur (and hence two partial currents flow) at the same time. This was done with a modified tip generation/substrate collection mode where the two reactions occur on the tip electrode, and the substrate electrode is held at a potential to collect only one of the products, allowing the determination of the individual partial currents. Thus, by using the substrate electrode current and the difference between the tip and substrate electrode currents, the two reactions occurring on the tip electrode can be separated. As a test case for this new method, we investigated proton reduction on Mn, a reaction that, because of the highly corrosive nature of Mn, to our knowledge has never before been directly measured. This test was carried out using a Mn tip electrode and a Pt substrate electrode. Using a three-dimensional COMSOL Multiphysics simulation, we were able to accurately determine the tip/substrate distance with this electrode, and by fitting simulations to experimental data, we were able to determine an exchange current density, log(j(0)) = -4.7 ± 0.7 A cm(-2), for proton reduction on Mn in strong acid. This result corrects a literature value and was used in a pattern recognition algorithm reported in a companion manuscript.

  11. Generation of 15W femtosecond laser pulse from a Kerr-lens mode-locked Yb:YAG thin-disk oscillator

    NASA Astrophysics Data System (ADS)

    Peng, Yingnan; Zhang, Jinwei; Wang, Zhaohua; Zhu, Jiangfeng; Li, Dehua; Wei, Zhiyi

    2016-09-01

    We demonstrated a robust power-scalable Kerr-lens mode-locked (KLM) operation based on a Yb:YAG thin-disk oscillator. 15-W, 272-fs pulses were realized at a repetition rate of 86.7 MHz with an additional Kerr medium and a 2.5 mm hard aperture in the cavity. 247-fs pulses with an average power of 11 W could also be obtained by using a 2.4 mm hard aperture. Based on this shorter pulse, high efficient second-harmonic generation (SHG) was performed with a 1.7-mm-long LiB3O5 (LBO) crystal. The SHG laser power was up to 5 W with the power fluctuation RMS of 1% measured over one hour. Project supported by the National Basic Research Program of China (Grant No. 2013CB922402), the National Major Instrument Program of China (Grant No. 2012YQ120047), and the National Natural Science Foundation of China (Grant Nos. 11434016 and 61210017).

  12. Enhanced visibility of two-mode thermal squeezed states via degenerate parametric amplification and resonance

    NASA Astrophysics Data System (ADS)

    Mahboob, I.; Okamoto, H.; Yamaguchi, H.

    2016-08-01

    Two-mode squeezed states, generated via non-degenerate parametric down-conversion, are invariably revealed via their entangled vacuum or correlated thermal fluctuations. Here, two-mode thermal squeezed states, generated in an electromechanical system, are made bright by means of degenerate parametric amplification of their constituent modes to the point where they are almost perfect, even when seeded from low intensity non-degenerate parametric down-conversion. More dramatically, activating the degenerate parametric resonances of the underlying modes yields perfect correlations which can be resolved via the coordinated switching of their phase bi-stable vibrations, without recourse to monitoring their thermal fluctuations. This ability to enhance the two-mode squeezed states and to decipher them without needing to observe their intrinsic noise is supported by both analytical and numerical modelling and it suggests that the technical constraints to making this phenomenon more widely available can be dramatically relaxed.

  13. Mechanisms of coordination in distributed neural circuits: encoding coordinating information.

    PubMed

    Smarandache-Wellmann, Carmen; Grätsch, Swantje

    2014-04-16

    We describe synaptic connections through which information essential for encoding efference copies reaches two coordinating neurons in each of the microcircuits that controls limbs on abdominal segments of the crayfish, Pacifastacus leniusculus. In each microcircuit, these coordinating neurons fire bursts of spikes simultaneously with motor neurons. These bursts encode timing, duration, and strength of each motor burst. Using paired microelectrode recordings, we demonstrate that one class of nonspiking neurons in each microcircuit's pattern-generating kernel--IPS--directly inhibits the ASCE coordinating neuron that copies each burst in power-stroke (PS) motor neurons. This inhibitory synapse parallels IPS's inhibition of the same PS motor neurons. Using a disynaptic pathway to control its membrane potential, we demonstrate that a second type of nonspiking interneuron in the pattern-generating kernel--IRSh--inhibits the DSC coordinating neuron that copies each burst in return-stroke (RS) motor neurons. This inhibitory synapse parallels IRS's inhibition of the microcircuit's RS motor neurons. Experimental changes in the membrane potential of one IPS or one IRSh neuron simultaneously changed the strengths of motor bursts, durations, numbers of spikes, and spike frequency in the simultaneous ASCE and DSC bursts. ASCE and DSC coordinating neurons link the segmentally distributed microcircuits into a coordinated system that oscillates with the same period and with stable phase differences. The inhibitory synapses from different pattern-generating neurons that parallel their inhibition of different sets of motor neurons enable ASCE and DSC to encode details of each oscillation that are necessary for stable, adaptive synchronization of the system.

  14. Modeling of fast neutral-beam-generated ion effects on MHD-spectroscopic observations of resistive wall mode stability in DIII-D plasmas

    SciTech Connect

    Turco, F. Hanson, J. M.; Navratil, G. A.; Turnbull, A. D.

    2015-02-15

    Experiments conducted at DIII-D investigate the role of drift kinetic damping and fast neutral beam injection (NBI)-ions in the approach to the no-wall β{sub N} limit. Modelling results show that the drift kinetic effects are significant and necessary to reproduce the measured plasma response at the ideal no-wall limit. Fast neutral-beam ions and rotation play important roles and are crucial to quantitatively match the experiment. In this paper, we report on the model validation of a series of plasmas with increasing β{sub N}, where the plasma stability is probed by active magnetohydrodynamic (MHD) spectroscopy. The response of the plasma to an externally applied field is used to probe the stable side of the resistive wall mode and obtain an indication of the proximity of the equilibrium to an instability limit. We describe the comparison between the measured plasma response and that calculated by means of the drift kinetic MARS-K code [Liu et al., Phys. Plasmas 15, 112503 (2008)], which includes the toroidal rotation, the electron and ion drift-kinetic resonances, and the presence of fast particles for the modelled plasmas. The inclusion of kinetic effects allows the code to reproduce the experimental results within ∼13% for both the amplitude and phase of the plasma response, which is a significant improvement with respect to the undamped MHD-only model. The presence of fast NBI-generated ions is necessary to obtain the low response at the highest β{sub N} levels (∼90% of the ideal no-wall limit). The toroidal rotation has an impact on the results, and a sensitivity study shows that a large variation in the predicted response is caused by the details of the rotation profiles at high β{sub N}.

  15. Generation of sub-100-fsec pulses tunable near 497 nm from a colliding-pulse mode-locked ring dye laser

    SciTech Connect

    French, P.M.W.; Taylor, J.R.

    1988-06-01

    A colliding-pulse mode-locked ring dye laser with Coumarin 102 passively mode locked by 3,3'-diethyloxacarbocyanine iodide has been developed. Pulses of less than 100-fsec duration have been obtained from 493 to 502 nm at a repetition rate of 160 MHz. A similar operation has also been obtained with alternative saturable absorbers.

  16. PHYSICAL EFFECTS OCCURRING DURING GENERATION AND AMPLIFICATION OF LASER RADIATION: Spatial phase fluctuations of the fundamental laser mode caused by spontaneous emission

    NASA Astrophysics Data System (ADS)

    Belinskiĭ, A. V.; Chirkin, Anatolii S.

    1989-02-01

    A calculation is reported of the degree of spatial coherence of the fundamental radiation mode subject to phase fluctuations in space. It is shown that the degree of spatial coherence (within the beam width) is perturbed only slightly by these fluctuations, compared with subthreshold excitation of higher transverse modes.

  17. Work Coordination Engine

    NASA Technical Reports Server (NTRS)

    Zendejas, Silvino; Bui, Tung; Bui, Bach; Malhotra, Shantanu; Chen, Fannie; Kim, Rachel; Allen, Christopher; Luong, Ivy; Chang, George; Sadaqathulla, Syed

    2009-01-01

    The Work Coordination Engine (WCE) is a Java application integrated into the Service Management Database (SMDB), which coordinates the dispatching and monitoring of a work order system. WCE de-queues work orders from SMDB and orchestrates the dispatching of work to a registered set of software worker applications distributed over a set of local, or remote, heterogeneous computing systems. WCE monitors the execution of work orders once dispatched, and accepts the results of the work order by storing to the SMDB persistent store. The software leverages the use of a relational database, Java Messaging System (JMS), and Web Services using Simple Object Access Protocol (SOAP) technologies to implement an efficient work-order dispatching mechanism capable of coordinating the work of multiple computer servers on various platforms working concurrently on different, or similar, types of data or algorithmic processing. Existing (legacy) applications can be wrapped with a proxy object so that no changes to the application are needed to make them available for integration into the work order system as "workers." WCE automatically reschedules work orders that fail to be executed by one server to a different server if available. From initiation to completion, the system manages the execution state of work orders and workers via a well-defined set of events, states, and actions. It allows for configurable work-order execution timeouts by work-order type. This innovation eliminates a current processing bottleneck by providing a highly scalable, distributed work-order system used to quickly generate products needed by the Deep Space Network (DSN) to support space flight operations. WCE is driven by asynchronous messages delivered via JMS indicating the availability of new work or workers. It runs completely unattended in support of the lights-out operations concept in the DSN.

  18. Asymmetric corner frequency in the 1/f FM-noise PSD of optical frequency combs generated by quantum-dash mode-locked lasers

    NASA Astrophysics Data System (ADS)

    Panapakkam, V.; Anthur, A.; Vujicic, V.; Gaimard, Q.; Merghem, K.; Aubin, G.; Lelarge, F.; Viktorov, E.; Barry, L. P.; Ramdane, A.

    2016-10-01

    We experimentally investigate the corner frequency in the 1/f frequency noise of the longitudinal modes of an InAs/InP quantum-dash based single-section passive mode-locked laser. The corner frequency features a strong asymmetry across the optical frequency comb with the values ranging from 10 MHz in the low-frequency side to 180 MHz in the high-frequency side. Actively mode-locking the laser induces a reduction in the corner frequency as it changes from 3 MHz in the low-frequency side to 70 MHz in the high-frequency side and the asymmetry persists.

  19. Generation of stable high order harmonic noise-like pulses in a passively mode-locked double clad fiber ring laser

    NASA Astrophysics Data System (ADS)

    Hernandez-Garcia, J. C.; Pottiez, O.; Ibarra-Escamilla, B.; Estudillo-Ayala, J. M.; Rojas-Laguna, R.; Kuzin, E.; Muñoz-Lopez, A.; Filoteo-Razo, J. D.

    2015-03-01

    We study a passively mode-locked double-clad Erbium-Ytterbium fiber ring laser producing noise-like pulse through nonlinear polarization evolution and polarization selection. Single noise-like pulsing is only observed at moderate pump power. As pump power is increased, and through polarization controllers adjustments, harmonic mode-locking of growing order were successively appearing. For pump powers close to the damage threshold of the setup, we reach harmonic orders beyond 1200 and repetition frequencies in excess of a quarter of a GHz. Finally, these experimental results could be useful in the quest for higher pulse energies and higher repetition rates in passively mode-locked fiber lasers.

  20. Cartesian-coordinate dimensioning for plumbing systems

    NASA Technical Reports Server (NTRS)

    Buirgy, P. A.

    1971-01-01

    Nonprogressive dimensioning method specifies Cartesian coordinates for each critical point in detail drawings of precision plumbing and ducting components to avoid tolerance accumulation. Method permits direct fabrication of tubing shapes without necessitating generation of a preproduction tubing mockup.

  1. ASC Coordinate Transformation---The Pixlib Library

    NASA Astrophysics Data System (ADS)

    He, H.; McDowell, J.; Conroy, M.

    We describe a coordinate library for AXAF data analysis. The library handles transformations between celestial coordinates and instrumental (mirror, focal plane, detector pixel) coordinate systems. The need for careful transformations is driven by the accuracy of the detectors and the attitude determination system. The coordinate systems are characterized by parameter files generated from experimental and calibration data. Transformation calculations are performed by matrix-representation routines for maximum flexibility. This library is implemented in ANSI C, and uses the SAO IRAF-compatible parameter interface.

  2. Coordination modes of tyrosinate-ligated catalase-type heme enzymes: magnetic circular dichroism studies of Plexaura homomalla allene oxide synthase, Mycobacterium avium ssp. paratuberculosis protein-2744c, and bovine liver catalase in their ferric and ferrous states.

    PubMed

    Bandara, D M Indika; Sono, Masanori; Bruce, Grant S; Brash, Alan R; Dawson, John H

    2011-12-01

    Bovine liver catalase (BLC), catalase-related allene oxide synthase (cAOS) from Plexaura homomalla, and a recently isolated protein from the cattle pathogen Mycobacterium avium ssp. paratuberculosis (MAP-2744c (MAP)) are all tyrosinate-ligated heme enzymes whose crystal structures have been reported. cAOS and MAP have low (<20%) sequence similarity to, and significantly different catalytic functions from, BLC. cAOS transforms 8R-hydroperoxy-eicosatetraenoic acid to an allene epoxide, whereas the MAP protein is a putative organic peroxide-dependent peroxidase. To elucidate factors influencing the functions of these and related heme proteins, we have investigated the heme iron coordination properties of these tyrosinate-ligated heme enzymes in their ferric and ferrous states using magnetic circular dichroism and UV-visible absorption spectroscopy. The MAP protein shows remarkable spectral similarities to cAOS and BLC in its native Fe(III) state, but clear differences from ferric proximal heme ligand His93Tyr Mb (myoglobin) mutant, which may be attributed to the presence of an Arg(+)-N(ω)-H···¯O-Tyr (proximal heme axial ligand) hydrogen bond in the first three heme proteins. Furthermore, the spectra of Fe(III)-CN¯, Fe(III)-NO, Fe(II)-NO (except for five-coordinate MAP), Fe(II)-CO, and Fe(II)-O(2) states of cAOS and MAP, but not H93Y Mb, are also similar to the corresponding six-coordinate complexes of BLC, suggesting that a tyrosinate (Tyr-O¯) is the heme axial ligand trans to the bound ligands in these complexes. The Arg(+)-N(ω)-H to ¯O-Tyr hydrogen bond would be expected to modulate the donor properties of the proximal tyrosinate oxyanion and, combined with the subtle differences in the catalytic site structures, affect the activities of cAOS, MAP and BLC.

  3. Reaction Coordinates and Mechanistic Hypothesis Tests

    NASA Astrophysics Data System (ADS)

    Peters, Baron

    2016-05-01

    Reaction coordinates are integral to several classic rate theories that can (a) predict kinetic trends across conditions and homologous reactions, (b) extract activation parameters with a clear physical interpretation from experimental rates, and (c) enable efficient calculations of free energy barriers and rates. New trajectory-based rare events methods can provide rates directly from dynamical trajectories without a reaction coordinate. Trajectory-based frameworks can also generate ideal (but abstract) reaction coordinates such as committors and eigenfunctions of the master equation. However, rates and mechanistic insights obtained from trajectory-based methods and abstract coordinates are not readily generalized across simulation conditions or reaction families. We discuss methods for identifying physically meaningful reaction coordinates, including committor analysis, variational transition state theory, Kramers-Langer-Berezhkovskii-Szabo theory, and statistical inference methods that can use path sampling data to screen, mix, and optimize thousands of trial coordinates. Special focus is given to likelihood maximization and inertial likelihood maximization approaches.

  4. Developmental coordination disorder

    MedlinePlus

    ... with visual or fine motor coordination (for example, writing, using scissors, tying shoelaces, or tapping one finger ... take notes may help children who have trouble writing. Children with developmental coordination disorder are more likely ...

  5. Multibody dynamics: Modeling component flexibility with fixed, free, loaded, constraint, and residual modes

    NASA Technical Reports Server (NTRS)

    Spanos, John T.; Tsuha, Walter S.

    1989-01-01

    The assumed-modes method in multibody dynamics allows the elastic deformation of each component in the system to be approximated by a sum of products of spatial and temporal functions commonly known as modes and modal coordinates respectively. The choice of component modes used to model articulating and non-articulating flexible multibody systems is examined. Attention is directed toward three classical Component Mode Synthesis (CMS) methods whereby component normal modes are generated by treating the component interface (I/F) as either fixed, free, or loaded with mass and stiffness contributions from the remaining components. The fixed and free I/F normal modes are augmented by static shape functions termed constraint and residual modes respectively. A mode selection procedure is outlined whereby component modes are selected from the Craig-Bampton (fixed I/F plus constraint), MacNeal-Rubin (free I/F plus residual), or Benfield-Hruda (loaded I/F) mode sets in accordance with a modal ordering scheme derived from balance realization theory. The success of the approach is judged by comparing the actuator-to-sensor frequency response of the reduced order system with that of the full order system over the frequency range of interest. A finite element model of the Galileo spacecraft serves as an example in demonstrating the effectiveness of the proposed mode selection method.

  6. Cognitive Personal Coordination Assistants

    DTIC Science & Technology

    2005-03-01

    of TÆMS [2, 7], DTC agent scheduling [16, 19, 12], GPGP agent coordination [2, 1, 6], and a similar approach to team coordination [17]. From the...a tactical TÆMS view, and how a Generalized Partial Global Planning ( GPGP ) coordination mechanism operates over the tactical views. Although we don’t...Norman Carver, Alan Garvey, Daniel Neiman, and Nagendra Prasad. Evolution of the GPGP Domain-Independent Coordination Framework. Computer Science

  7. Exploring transverse pattern formation in a dual-polarization self-mode-locked monolithic Yb: KGW laser and generating a 25-GHz sub-picosecond vortex beam via gain competition.

    PubMed

    Chang, M T; Liang, H C; Su, K W; Chen, Y F

    2016-04-18

    Formation of transverse modes in a dual-polarization self-mode-locked monolithic Yb: KGW laser under high-power pumping is thoroughly explored. It is experimentally observed that the polarization-resolved transverse patterns are considerably affected by the pump location in the transverse plane of the gain medium. In contrast, the longitudinal self-mode-locking is nearly undisturbed by the pump position, even under the high-power pumping. Under central pumping, a vortex beam of the Laguerre-Gaussian LGp,l mode with p = 1 and l = 1 can be efficiently generated through the process of the gain competition with a sub-picosecond pulse train at 25.3 GHz and the output power can be up to 1.45 W at a pump power of 10.0 W. Under off-center pumping, the symmetry breaking causes the transverse patterns to be dominated by the high-order Hermite-Gaussian modes. Numerical analyses are further performed to manifest the symmetry breaking induced by the off-center pumping.

  8. Quantifying coordination and coordination variability in backward versus forward running: Implications for control of motion.

    PubMed

    Mehdizadeh, Sina; Arshi, Ahmed Reza; Davids, Keith

    2015-07-01

    The aims of this study were to compare coordination and coordination variability in backward and forward running and to investigate the effects of speed on coordination variability in both backward and forward running. Fifteen healthy male participants took part in this study to run forwards and backwards on a treadmill at 80%, 100% and 120% of their preferred running speeds. The coordinate data of passive reflective markers attached to body segments were recorded using motion capture systems. Coordination of shank-foot and thigh-shank couplings in sagittal plane was quantified using the continuous relative phase method. Coordination variability was calculated as the standard deviation of a coordination pattern over 50 strides. Cross-correlation coefficients and associated phase shifts were determined to quantify similarity in coordination patterns between forward and backward running. Our results demonstrated that the coordination pattern in a gait cycle of backward running was in reverse to that of forward running at all speeds implying that the same neural circuitry is responsible for regulating both forward and backward running gaits. In addition, results demonstrated that there was an average of approximately 11% phase shift between the coordination patterns of backward and forward running which indicates that a single underlying mechanism might be responsible for generating motor patterns in both forward and backward running. Finally, backward running had significantly higher magnitude of coordination variability compared to forward running, signifying that more degrees of freedom were involved in backward running. Speed however, did not affect coordination variability in either task.

  9. Processing Coordination Ambiguity

    ERIC Educational Resources Information Center

    Engelhardt, Paul E.; Ferreira, Fernanda

    2010-01-01

    We examined temporarily ambiguous coordination structures such as "put the butter in the bowl and the pan on the towel." Minimal Attachment predicts that the ambiguous noun phrase "the pan" will be interpreted as a noun-phrase coordination structure because it is syntactically simpler than clausal coordination. Constraint-based…

  10. Literacy Coordinators' Handbook.

    ERIC Educational Resources Information Center

    Department for Education and Skills, London (England).

    This handbook is designed to provide support for England's National Literacy Strategy's Literacy Coordinators leading and coordinating literacy across the school. The handbook is designed as a working document and will contain additional materials, LEA (local education authorities) guidance, and additional papers which Coordinators may choose to…

  11. Experimental study of complex mixed-mode oscillations generated in a Bonhoeffer-van der Pol oscillator under weak periodic perturbation

    SciTech Connect

    Shimizu, Kuniyasu; Sekikawa, Munehisa; Inaba, Naohiko

    2015-02-15

    Bifurcations of complex mixed-mode oscillations denoted as mixed-mode oscillation-incrementing bifurcations (MMOIBs) have frequently been observed in chemical experiments. In a previous study [K. Shimizu et al., Physica D 241, 1518 (2012)], we discovered an extremely simple dynamical circuit that exhibits MMOIBs. Our model was represented by a slow/fast Bonhoeffer-van der Pol circuit under weak periodic perturbation near a subcritical Andronov-Hopf bifurcation point. In this study, we experimentally and numerically verify that our dynamical circuit captures the essence of the underlying mechanism causing MMOIBs, and we observe MMOIBs and chaos with distinctive waveforms in real circuit experiments.

  12. Relationships between coordination, active drag and propelling efficiency in crawl.

    PubMed

    Seifert, Ludovic; Schnitzler, Christophe; Bideault, Gautier; Alberty, Morgan; Chollet, Didier; Toussaint, Huub Martin

    2015-02-01

    This study examines the relationships between the index of coordination (IdC) and active drag (D) assuming that at constant average speed, average drag equals average propulsion. The relationship between IdC and propulsive efficiency (ep) was also investigated at maximal speed. Twenty national swimmers completed two incremental speed tests swimming front crawl with arms only in free condition and using a measurement of active drag system. Each test was composed of eight 25-m bouts from 60% to 100% of maximal intensity whereby each lap was swum at constant speed. Different regression models were tested to analyse IdC-D relationship. Correlation between IdC and ep was calculated. IdC was linked to D by linear regression (IdC=0.246·D-27.06; R(2)=0.88, P<.05); swimmers switched from catch-up to superposition coordination mode at a speed of ∼1.55ms(-1) where average D is ∼110N. No correlation between IdC and ep at maximal speed was found. The intra-individual analysis revealed that coordination plays an important role in scaling propulsive forces with higher speed levels such that these are adapted to aquatic resistance. Inter-individual analysis showed that high IdC did not relate to a high ep suggesting an individual optimization of force and power generation is at play to reach high speeds.

  13. Some studies on generalized coordinate sets for polyatomic molecules.

    PubMed

    Li, Wenjin; Ma, Ao

    2015-12-14

    Generalized coordinates are widely used in various analyses of the trajectories of polyatomic molecules from molecular dynamics simulations, such as normal mode analysis and force distribution analysis. Here, we presented detailed discussions on the properties of some specific sets of generalized coordinates, which separate translational, rotational, and vibrational motions of a molecule from one another once the trajectories of dynamical systems are known. Efficient methods were suggested for estimating the transformation matrix between generalized and Cartesian coordinates. Some properties of the well-known BAT coordinates (bond length, angle, and torsional coordinates) were discussed as well.

  14. A parametric study for the generation of ion Bernstein modes from a discrete spectrum to a continuous one in the inner magnetosphere. I. Linear theory

    NASA Astrophysics Data System (ADS)

    Sun, Jicheng; Gao, Xinliang; Chen, Lunjin; Lu, Quanming; Tao, Xin; Wang, Shui

    2016-02-01

    Ion Bernstein modes, also known as magnetosonic waves in the magnetospheric community, are considered to play an important role in radiation belt electron acceleration. The detailed properties of perpendicular magnetosonic waves excited in the inner magnetosphere by a tenuous proton ring distribution are investigated in a two series paper with a combination of the linear theory and one-dimensional particle-in-cell simulations. Here, in this paper, we study the properties of the excited magnetosonic waves under different plasma conditions with the linear theory. When the proton to electron mass ratio or the ratio of the light speed to the Alfven speed is small, the excited magnetosonic waves are prone to having a discrete spectrum with only several wave modes. With the increase of the proton to electron mass ratio or the ratio of the light speed to the Alfven speed, the lower hybrid frequency also increases, which leads to the increase of both the number and frequency of the excited wave modes. Meanwhile, the growth rate of these wave modes also increases. When the proton to electron mass ratio or the ratio of the light speed to the Alfven speed is sufficiently large, the spectrum of the excited magnetic waves becomes continuous due to the overlapping of the adjacent wave modes. The increase of the density of the protons with the ring distribution can also result in the increase of the growth rate, which may also change the discrete spectrum of the excited waves to a continuous one, while the increase of the ring velocity of the tenuous proton ring distribution leads to a broader spectrum, but with a smaller growth rate.

  15. Activation of nuclear factor erythroid 2-related factor 2 coordinates dimethylarginine dimethylaminohydrolase/PPAR-γ/endothelial nitric oxide synthase pathways that enhance nitric oxide generation in human glomerular endothelial cells.

    PubMed

    Luo, Zaiming; Aslam, Shakil; Welch, William J; Wilcox, Christopher S

    2015-04-01

    Dimethylarginine dimethylaminohydrolase (DDAH) degrades asymmetric dimethylarginine, which inhibits nitric oxide (NO) synthase (NOS). Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcriptional factor that binds to antioxidant response elements and transcribes many antioxidant genes. Because the promoters of the human DDAH-1 and DDAH-2, endothelial NOS (eNOS) and PPAR-γ genes contain 2 to 3 putative antioxidant response elements, we hypothesized that they were regulated by Nrf2/antioxidant response element. Incubation of human renal glomerular endothelial cells with the Nrf2 activator tert-butylhydroquinone (20 μmol·L(-1)) significantly (P<0.05) increased NO and activities of NOS and DDAH and decreased asymmetric dimethylarginine. It upregulated genes for hemoxygenase-1, eNOS, DDAH-1, DDAH-2, and PPAR-γ and partitioned Nrf2 into the nucleus. Knockdown of Nrf2 abolished these effects. Nrf2 bound to one antioxidant response element on DDAH-1 and DDAH-2 and PPAR-γ promoters but not to the eNOS promoter. An increased eNOS and phosphorylated eNOS (P-eNOSser-1177) expression with tert-butylhydroquinone was prevented by knockdown of PPAR-γ. Expression of Nrf2 was reduced by knockdown of PPAR-γ, whereas PPAR-γ was reduced by knockdown of Nrf2, thereby demonstrating 2-way positive interactions. Thus, Nrf2 transcribes HO-1 and other genes to reduce reactive oxygen species, and DDAH-1 and DDAH-2 to reduce asymmetric dimethylarginine and PPAR-γ to increase eNOS and its phosphorylation and activity thereby coordinating 3 pathways that enhance endothelial NO generation.

  16. The copper(II) and zinc(II) coordination mode of HExxH and HxxEH motif in small peptides: the role of carboxylate location and hydrogen bonding network.

    PubMed

    Grasso, Giuseppe; Magrì, Antonio; Bellia, Francesco; Pietropaolo, Adriana; La Mendola, Diego; Rizzarelli, Enrico

    2014-01-01

    Copper(II) and zinc(II) complexes with two hexapeptides encompassing HExxH and HxxEH motif were characterized by means of a combined experimental and theoretical approach. Parallel tempering and density functional theory (DFT) investigations show the presence of different hydrogen bonding networks between the copper(II) and zinc(II) complexes with the two peptides, suggesting a significant contribution of these non-covalent interactions to the stability constant values. The glutamate carboxylate group has a direct role in metal ion binding. The location of this amino acid along the sequence of the investigated peptides is critical to determine thermodynamic and spectroscopic features of the copper(II) complex species, whereas is less relevant in the zinc(II) complexes formation. Electrospray ionization mass spectrometry (ESI-MS) characterization of the zinc(II) complex species show that in the [ZnH-2L] two deprotonated amide nitrogen atoms are involved in the metal coordination environment, an uncommon behavior in zinc(II) complexes for multi-histidine ligands.

  17. Coordination mode of pentadentate ligand derivative of 5-amino-1,3,4-thiadiazole-2-thiol with nickel(II) and copper(II) metal ions: Synthesis, spectroscopic characterization, molecular modeling and fungicidal study

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Gautam, Seema; Kumar, Amit; Madan, Molly

    2015-02-01

    Complexes of nickel(II), and copper(II) were synthesized with pantadentate ligand i.e. 3,3‧-thiodipropionicacid-bis(5-amino-1,3,4-thiadiazole-2-thiol) (L). The ligand was synthesized by the condensation of thiodipropionic acid and 5-amino-1,3,4-thiadiazole-2-thiol in 1:2 ratio, respectively. Synthesized ligand was characterized by elemental analysis, mass, 1H NMR, IR, and molecular modeling. All the complexes were characterized by elemental analysis, molar conductance, magnetic moment, IR, electronic spectra, ESR, and molecular modeling. The newly synthesized complexes possessed general composition [M(L)X2] where M = Ni(II), Cu(II), L = pantadentate ligand and X = Cl-, CH3COO-. The IR spectral data indicated that the ligand behaved as a pantadentate ligand and coordinated to the metal ion through N2S3 donor atoms. The molar conductance value of Ni(II), and Cu(II) complexes in DMSO corresponded to their electrolytic behavior. On the basis of spectral study, octahedral and tetragonal geometry was assigned for Ni(II) and Cu(II) complexes, respectively. In vitro fungicidal study of ligand and its complexes was investigated against fungi Candida albicans, Candida parapsilosis, Candidia krusei, and Candida tropicalis by means of well diffusion method.

  18. Coordination mode of pentadentate ligand derivative of 5-amino-1,3,4-thiadiazole-2-thiol with nickel(II) and copper(II) metal ions: synthesis, spectroscopic characterization, molecular modeling and fungicidal study.

    PubMed

    Chandra, Sulekh; Gautam, Seema; Kumar, Amit; Madan, Molly

    2015-02-05

    Complexes of nickel(II), and copper(II) were synthesized with pantadentate ligand i.e. 3,3'-thiodipropionicacid-bis(5-amino-1,3,4-thiadiazole-2-thiol) (L). The ligand was synthesized by the condensation of thiodipropionic acid and 5-amino-1,3,4-thiadiazole-2-thiol in 1:2 ratio, respectively. Synthesized ligand was characterized by elemental analysis, mass, (1)H NMR, IR, and molecular modeling. All the complexes were characterized by elemental analysis, molar conductance, magnetic moment, IR, electronic spectra, ESR, and molecular modeling. The newly synthesized complexes possessed general composition [M(L)X2] where M = Ni(II), Cu(II), L = pantadentate ligand and X = Cl(-), CH3COO(-). The IR spectral data indicated that the ligand behaved as a pantadentate ligand and coordinated to the metal ion through N2S3 donor atoms. The molar conductance value of Ni(II), and Cu(II) complexes in DMSO corresponded to their electrolytic behavior. On the basis of spectral study, octahedral and tetragonal geometry was assigned for Ni(II) and Cu(II) complexes, respectively. In vitro fungicidal study of ligand and its complexes was investigated against fungi Candida albicans, Candida parapsilosis, Candidia krusei, and Candida tropicalis by means of well diffusion method.

  19. Unusual reactions of [{micro-(phthalazine-N2:N3)}Fe2(micro-CO)(CO)6] with organolithium reagents. A novel coordination mode of 1,2-diazane diiron carbonyl compounds.

    PubMed

    Xiao, Nu; Xu, Qiang; Sun, Jie; Chen, Jiabi

    2006-01-28

    [{Micro-(phthalazine-N2:N3)}Fe2(micro-CO)(CO)6](1) reacts with organolithium reagents, RLi (R = CH3, C6H5, p-CH3C6H4, p-CH3OC6H4, p-CF3C6H4, p-C6H5C6H4), followed by treatment with Me3SiCl to give the novel diiron carbonyl complexes with a saturated N-N six-membered diazane ring ligand, [{C6H4CH(R)NNCH2}Fe2(C=O)(CO)6](2, R = CH3; 3, R = C6H5; 4, R =p-CH3C6H4; 5, R =p-CH3OC6H4; 6, R =p-CF3C6H4; 7, R =p-C6H5C6H4). Compounds 4 and 5 were treated with [(NH4)2Ce(NO3)6] to afford the aryl-substituted phthalazine-coordinated diiron carbonyl compounds [(micro-{1-(p-CH3C6H4)-phthalazine-N2:N3})Fe2(micro-CO)(CO)6](8) and [(micro-{1-(p-CH3OC6H4)-phthalazine-N2:N3})Fe2(micro-CO)(CO)6](9), respectively. The structures of complexes 4 and 9 have been established by X-ray diffraction studies.

  20. 10 kHz ps 1342 nm laser generation by an electro-optically cavity-dumped mode-locked Nd:YVO4 laser

    NASA Astrophysics Data System (ADS)

    Chen, Ying; Liu, Ke; He, Li-jiao; Yang, Jing; Zong, Nan; Yang, Feng; Gao, Hong-wei; Liu, Zhao; Yuan, Lei; Lan, Ying-jie; Bo, Yong; Peng, Qin-jun; Cui, Da-fu; Xu, Zu-yan

    2017-01-01

    We have demonstrated an electro-optically cavity-dumped mode-locked (CDML) picosecond Nd:YVO4 laser at 1342 nm with 880 nm diode-laser direct pumping. At a repetition rate of 10 kHz, an average output power of 0.119 W was achieved, corresponding to a pulse energy of 11.9 μJ. Compared with the continuous wave mode-locking pulse energy of 17.5 nJ, the CDML pulse energy was 680 times higher. The pulse width was measured to be 33.4 ps, resulting in the peak power of 356 kW. Meanwhile, the beam quality was nearly diffraction limited with an average beam quality factor M2 of 1.29.

  1. Generation of high energy square-wave pulses in all anomalous dispersion Er:Yb passive mode locked fiber ring laser.

    PubMed

    Semaan, Georges; Ben Braham, Fatma; Salhi, Mohamed; Meng, Yichang; Bahloul, Faouzi; Sanchez, François

    2016-04-18

    We have experimentally demonstrated square pulses emission from a co-doped Er:Yb double-clad fiber laser operating in anomalous dispersion DSR regime using the nonlinear polarization evolution technique. Stable mode-locked pulses have a repetition rate of 373 kHz with 2.27 µJ energy per pulse under a pumping power of 30 W in cavity. With the increase of pump power, both the duration and the energy of the output square pulses broaden. The experimental results demonstrate that the passively mode-locked fiber laser operating in the anomalous regime can also realize a high-energy pulse, which is different from the conventional low-energy soliton pulse.

  2. Comment on ‘Solving the two-mode squeezed harmonic oscillator and the kth-order harmonic generation in Bargmann-Hilbert spaces’

    NASA Astrophysics Data System (ADS)

    Lo, C. F.

    2014-02-01

    Recently Zhang (2013 J. Phys. A: Math. Theor. 46 455302) proposed an analytical approach to solve the time-independent Schrödinger equation for the single-mode and two-mode squeezed harmonic oscillators in the Bargmann space of entire functions. In this comment we show that the eigenfunctions of these two systems exist in closed form and are expressed in terms of the Hermite polynomials. Moreover, since both oscillators exhibit the SU(1,1) dynamical symmetry, the eigenvalue problem can be tackled in a unified manner. In the Hilbert space of analytic functions of a complex variable in the unit disc, the energy eigenvalue equations involve first-order ordinary differential equations only, so we can easily solve these equations to obtain simple closed-form solutions.

  3. Efficient high-power generation of visible and mid-infrared light by degenerate four-wave-mixing in a large-mode-area photonic-crystal fiber.

    PubMed

    Nodop, D; Jauregui, C; Schimpf, D; Limpert, J; Tünnermann, A

    2009-11-15

    An efficient and simple approach for converting pulsed near-IR laser radiation into visible and mid-IR light by exploiting degenerate four-wave-mixing in an endlessly single-mode, large-mode-area photonic-crystal fiber is presented. Coupling a 1 MHz, 200 ps, 8 W average power pulsed source emitting at 1064 nm into this fiber results in average powers of 3 W at 673 nm signal wavelength and of 450 mW at 2539 nm idler wavelength, respectively. The excellent pulse energy conversion efficiencies of 35% for the signal and 6% for the idler wavelength are due to the unique combination of characteristics of this type of fiber.

  4. PHYSICAL EFFECTS OCCURRING DURING GENERATION AND AMPLIFICATION OF LASER RADIATION: Nonlinear resonances of natural intensity fluctuations in a two-mode He-Ne/CH4 laser

    NASA Astrophysics Data System (ADS)

    Anishchenko, M. L.; Ermachenko, V. M.; Petrovskiĭ, V. N.; Protsenko, E. D.

    1989-02-01

    The influence of a nonlinear absorber (methane) on the natural intensity fluctuations in an He-Ne laser (λ = 3.39 μm) emitting two linearly and orthogonally polarized modes with a controlled intermode interaction was studied experimentally and theoretically for the first time. It was found that an intracavity methane cell increases appreciably the influence of the fluctuation sources on the natural intensity fluctuations.

  5. Highly efficient, versatile, self-Q-switched, high-repetition-rate microchip laser generating Ince-Gaussian modes for optical trapping

    NASA Astrophysics Data System (ADS)

    Dong, Jun; He, Yu; Zhou, Xiao; Bai, Shengchuang

    2016-03-01

    Lasers operating in the Ince-Gaussian (IG) mode have potential applications for optical manipulation of microparticles and formation of optical vortices, as well as for optical trapping and optical tweezers. Versatile, self-Q-switched, high-peak-power, high-repetition-rate Cr, Nd:YAG microchip lasers operating in the IG mode are implemented under tilted, tightly focused laser-diode pumping. An average output power of over 2 W is obtained at an absorbed pump power of 6.4 W. The highest optical-to-optical efficiency of 33.2% is achieved at an absorbed pump power of 3.9 W. Laser pulses with a pulse energy of 7.5 μJ, pulse width of 3.5 ns and peak power of over 2 kW are obtained. A repetition rate up to 335 kHz is reached at an absorbed pump power of 5.8 W. Highly efficient, versatile, IG-mode lasers with a high repetition rate and a high peak power ensure a better flexibility in particle manipulation and optical trapping.

  6. Highly efficient, versatile, self-Q-switched, high-repetition-rate microchip laser generating Ince–Gaussian modes for optical trapping

    SciTech Connect

    Jun Dong; Yu He; Xiao Zhou; Shengchuang Bai

    2016-03-31

    Lasers operating in the Ince-Gaussian (IG) mode have potential applications for optical manipulation of microparticles and formation of optical vortices, as well as for optical trapping and optical tweezers. Versatile, self-Q-switched, high-peak-power, high-repetition-rate Cr, Nd:YAG microchip lasers operating in the IG mode are implemented under tilted, tightly focused laser-diode pumping. An average output power of over 2 W is obtained at an absorbed pump power of 6.4 W. The highest optical-to-optical efficiency of 33.2% is achieved at an absorbed pump power of 3.9 W. Laser pulses with a pulse energy of 7.5 μJ, pulse width of 3.5 ns and peak power of over 2 kW are obtained. A repetition rate up to 335 kHz is reached at an absorbed pump power of 5.8 W. Highly efficient, versatile, IG-mode lasers with a high repetition rate and a high peak power ensure a better flexibility in particle manipulation and optical trapping. (control of laser radiation parameters)

  7. Molecular tectonics: generation and structural studies on 1- and 2D coordination networks based on a meta-cyclophane in 1,3-alternate conformation bearing four pyrazolyl units and cobalt, zinc and copper cations.

    PubMed

    Ehrhart, Jérôme; Planeix, Jean-Marc; Kyritsakas-Gruber, Nathalie; Hosseini, Mir Wais

    2009-08-28

    The combination of a [1111] metacyclophane blocked in 1,3-alternate conformation and bearing four pyrazolyl coordinating units with MX(2) (M = Co, Zn and X = Cl or Br) leads to the formation of crystals formed by packing of 2D coordination networks. In the case of CuBr(2), the formation of a 1D network was observed. Structural studies by X-ray diffraction methods on single crystals were performed on all cases reported.

  8. Accurate Simulation of Resonance-Raman Spectra of Flexible Molecules: An Internal Coordinates Approach.

    PubMed

    Baiardi, Alberto; Bloino, Julien; Barone, Vincenzo

    2015-07-14

    The interpretation and analysis of experimental resonance-Raman (RR) spectra can be significantly facilitated by vibronic computations based on reliable quantum-mechanical (QM) methods. With the aim of improving the description of large and flexible molecules, our recent time-dependent formulation to compute vibrationally resolved electronic spectra, based on Cartesian coordinates, has been extended to support internal coordinates. A set of nonredundant delocalized coordinates is automatically generated from the molecular connectivity thanks to a new general and robust procedure. In order to validate our implementation, a series of molecules has been used as test cases. Among them, rigid systems show that normal modes based on Cartesian and delocalized internal coordinates provide equivalent results, but the latter set is much more convenient and reliable for systems characterized by strong geometric deformations associated with the electronic transition. The so-called Z-matrix internal coordinates, which perform well for chain molecules, are also shown to be poorly suited in the presence of cycles or nonstandard structures.

  9. Dynamic Mode Decomposition Bio-Markers for Left Ventricle Flow

    NASA Astrophysics Data System (ADS)

    Borja, Maria; Martinez-Legazpi, Pablo; Benito, Yolanda; Yotti, Raquel; Fernandez-Aviles, Francisco; Bermejo, Javier; Del Alamo, Juan C.

    2016-11-01

    Dynamic mode decomposition (DMD) is a tool used in the fluid community to extract a set of modes that describe the underling fluid dynamics in a set of flow fields generated experimentally or by numerical simulations. Despite advances in medical imaging, characterization of some cardiac dysfunctions has remained a challenge and diagnosis is often subjective. This study presents a novel DMD method to objectively characterize left ventricular (LV) flow in healthy volunteers and patients with dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM). Our approach is based on assessing temporal evolution dependent mode structures from two-dimensional velocity fields, obtained experimentally using echocardiographic color Doppler velocimetry, and defined with a common unit normal moving LV coordinate system. Using the mode structures as a basis, we reconstruct the flow field, determine the key contributing modes, and obtain a reduce order model. Using 20 healthy volunteers, 20 DCM patients and 20 HCM patients, our results show quantitative and qualitative differences between healthy and in the DCM and HCM patients. This study suggests that temporal evolution dependent modes can be used as bio-markers to asses in-vivo LV flow.

  10. Sub-80 femtosecond pulses generation from a diode-pumped mode-locked Nd:Ca3La2(BO3)4 disordered crystal laser.

    PubMed

    Ma, Jie; Pan, Zhongben; Cai, Huaqiang; Yu, Haohai; Zhang, Huaijin; Shen, Deyuan; Tang, Dingyuan

    2016-04-01

    We experimentally demonstrated a diode-pumped sub-80 fs Nd:Ca3La2(BO3)4 disordered crystal laser. Pumping by an 808 nm fiber coupled laser diode, stable continuous-wave mode-locked pulses as short as 79 fs were achieved with a semiconductor saturable absorber mirror (SESAM). The ultrashort pulses had a repetition rate of ∼98.9  MHz at the central wavelength of about 1068 nm. To the best of our knowledge, this is the first demonstration of sub-100 fs pulses and the shortest mode-locked pulses generated from the Nd3+-doped crystal lasers.

  11. Explosive Emission Cathode Based on a Carbon Fiber for Long-Term Pulsed-Periodic Mode of Operation and its Application in a High-Power Microwave Pulse Generator Without External Magnetic Field

    NASA Astrophysics Data System (ADS)

    Kutenkov, O. P.; Pegel, I. V.; Totmeninov, E. M.

    2014-09-01

    Current characteristics and operating lifetime of the explosive emission cathode based on a carbon microfiber are investigated in the pulsed-periodic mode of operation with pulse duration of about 5 ns. Long-term (for up to 3.6 million pulses) tests of the cathode operating lifetime are carried out. Specific ablation of the fiber material equal to 2.4·10-4 g/C is obtained. Change in the morphology of the fiber surface during long-time operation caused by deposition of carbon from the cathode plasma is revealed. The microscopic electric field strength on the fiber surface is estimated taking into account the surface microrelief. The efficiency of microwave generation comparable with that of a velvet cathode in low (200 kV/cm) average electric field in the gap is obtained for the Cherenkov microwave generator with vacuum diode without external magnetic field of decimeter wavelength range based on the SINUS-7 pulsed-periodic high-current electron accelerator with current pulse duration of 50 ns. The operating lifetime no less than 105 pulses is demonstrated for the carbon fiber-based cathode of the microwave generator operating in the mode of pulse batch with duration of several seconds and pulse repetition frequency of 20-50 Hz.

  12. Passively mode-locked pulse generation in a c-cut Nd:LuVO4 laser at 1086 nm with a semiconductor saturable-absorber mirror

    NASA Astrophysics Data System (ADS)

    Lin, Ja-Hon; Yang, Pao-Keng; Lin, Wei-Cheng

    2012-04-01

    We demonstrate a diode-pumped passively mode-locked (ML) c-cut Nd:LuVO4 laser with central wavelength at 1086 nm by shifting the reflectance band of the SESAM into a longer wavelength to result in larger loss around 1068 nm. At 15 W absorbed pump power, the highest output power of the ML pulse was about 2.6 W that corresponded to the 17.3% optical-to-optical conversion efficiency and the slope efficiency of laser was about 22.9%. Using our ML laser as the light source, we have also successfully measured the saturation fluence of the SESAM at 1086 nm.

  13. Mode decomposition evolution equations

    PubMed Central

    Wang, Yang; Wei, Guo-Wei; Yang, Siyang

    2011-01-01

    Partial differential equation (PDE) based methods have become some of the most powerful tools for exploring the fundamental problems in signal processing, image processing, computer vision, machine vision and artificial intelligence in the past two decades. The advantages of PDE based approaches are that they can be made fully automatic, robust for the analysis of images, videos and high dimensional data. A fundamental question is whether one can use PDEs to perform all the basic tasks in the image processing. If one can devise PDEs to perform full-scale mode decomposition for signals and images, the modes thus generated would be very useful for secondary processing to meet the needs in various types of signal and image processing. Despite of great progress in PDE based image analysis in the past two decades, the basic roles of PDEs in image/signal analysis are only limited to PDE based low-pass filters, and their applications to noise removal, edge detection, segmentation, etc. At present, it is not clear how to construct PDE based methods for full-scale mode decomposition. The above-mentioned limitation of most current PDE based image/signal processing methods is addressed in the proposed work, in which we introduce a family of mode decomposition evolution equations (MoDEEs) for a vast variety of applications. The MoDEEs are constructed as an extension of a PDE based high-pass filter (Europhys. Lett., 59(6): 814, 2002) by using arbitrarily high order PDE based low-pass filters introduced by Wei (IEEE Signal Process. Lett., 6(7): 165, 1999). The use of arbitrarily high order PDEs is essential to the frequency localization in the mode decomposition. Similar to the wavelet transform, the present MoDEEs have a controllable time-frequency localization and allow a perfect reconstruction of the original function. Therefore, the MoDEE operation is also called a PDE transform. However, modes generated from the present approach are in the spatial or time domain and can be

  14. Improved Re-Configurable Sliding Mode Controller for Reusable Launch Vehicle of Second Generation Addressing Aerodynamic Surface Failures and Thrust Deficiencies

    NASA Technical Reports Server (NTRS)

    Shtessel, Yuri B.

    2002-01-01

    In this report we present a time-varying sliding mode control (TV-SMC) technique for reusable launch vehicle (RLV) attitude control in ascent and entry flight phases. In ascent flight the guidance commands Euler roll, pitch and yaw angles, and in entry flight it commands the aerodynamic angles of bank, attack and sideslip. The controller employs a body rate inner loop and the attitude outer loop, which are separated in time-scale by the singular perturbation principle. The novelty of the TVSMC is that both the sliding surface and the boundary layer dynamics can be varied in real time using the PD-eigenvalue assignment technique. This salient feature is used to cope with control command saturation and integrator windup in the presence of severe disturbance or control effector failure, which enhances the robustness and fault tolerance of the controller. The TV-SMC is developed and tuned up for the X-33 sub-orbital technology demonstration vehicle in launch and re-entry modes. A variety of nominal, dispersion and failure scenarios have tested via high fidelity 6DOF simulations using MAVERIC/SLIM simulation software.

  15. Cavity-length optimization for high energy pulse generation in a long cavity passively mode-locked all-fiber ring laser.

    PubMed

    Li, Nanxi; Xue, Jin; Ouyang, Chunmei; Wu, Kan; Wong, Jia Haur; Aditya, Sheel; Shum, Perry Ping

    2012-06-10

    In order to achieve higher pulse energy in a passively mode-locked fiber ring laser, a long cavity length is commonly implemented. However, a long cavity operating in the anomalous dispersion regime also leads to pulse broadening, which reduces the average pulse power. In this paper, the trade-off between cavity length and average pulse power is investigated with the aim of optimizing the cavity length to achieve maximum pulse energy. Numerical simulation results, presented here, indicate that there exists an optimum cavity length for which the pulse energy is maximum and the optimum length shifts as the pump power changes. The simulation results for a pump power of 500 mW are verified by measurements carried out on a long cavity nonlinear polarization rotation mode-locked all-fiber ring laser operating in the anomalous dispersion regime. With a repetition rate of 266 kHz for the dissipative solitons, we achieve a pulse energy of 139.1 nJ for a cavity length of 700 m. Higher pulse energy can be expected by using a pump laser diode with higher pump power.

  16. Phase Contrast Imaging Measurements of Short Wavelength Turbulence Generated by Shear in the QH-mode Edge on DIII-D

    NASA Astrophysics Data System (ADS)

    Rost, J. C.; Porkolab, M.; Dorris, J. R.; Marinoni, A.; Burrell, K. H.

    2012-10-01

    The Phase Contrast Imaging (PCI) diagnostic on DIII-D provides a line-integrated measurement of density fluctuations covering wavenumbers 2 to 30 cm-1. An outer gap scan during QH-mode with stationary plasma parameters allowed the PCI to sample a large range in kr/kθ. A narrow peak in turbulence amplitude is seen near the LCFS. The ExB Doppler shift allows the location to be determined precisely, showing two distinct regions of turbulence at 0.5 and 0.2 cm inside the LCFS with kr>0 and kr<0 respectively, consistent with the expected effects of shear in the Er well. PCI measurements at 200 kHz show that kθ=0.8 cm-1 with poloidal correlation length Lθ=6 cm. Using a simple non-isotropic turbulence model, we find that kr=3 cm-1 and Lr=0.5 cm, with n/n˜25% in the pedestal for this high-kr turbulence. These fluctuations, which are outside the parameter range accessible to most turbulence diagnostics, are large enough in amplitude to play a role in setting the pedestal structure. These PCI observations are qualitatively similar to those made in ELM-free H-mode and between ELMs suggesting that similar large kr turbulence may be important.

  17. The Binding Mode of Second-Generation Sulfonamide Inhibitors of MurD: Clues for Rational Design of Potent MurD Inhibitors

    PubMed Central

    Simčič, Mihael; Sosič, Izidor; Hodošček, Milan; Barreteau, Hélène; Blanot, Didier; Gobec, Stanislav; Grdadolnik, Simona Golič

    2012-01-01

    A series of optimized sulfonamide derivatives was recently reported as novel inhibitors of UDP-N-acetylmuramoyl-L-alanine:D-glutamate ligase (MurD). These are based on naphthalene-N-sulfonyl-D-glutamic acid and have the D-glutamic acid replaced with rigidified mimetics. Here we have defined the binding site of these novel ligands to MurD using 1H/13C heteronuclear single quantum correlation. The MurD protein was selectively 13C-labeled on the methyl groups of Ile (δ1 only), Leu and Val, and was isolated and purified. Crucial Ile, Leu and Val methyl groups in the vicinity of the ligand binding site were identified by comparison of chemical shift perturbation patterns among the ligands with various structural elements and known binding modes. The conformational and dynamic properties of the bound ligands and their binding interactions were examined using the transferred nuclear Overhauser effect and saturation transfer difference. In addition, the binding mode of these novel inhibitors was thoroughly examined using unrestrained molecular dynamics simulations. Our results reveal the complex dynamic behavior of ligand–MurD complexes and its influence on ligand–enzyme contacts. We further present important findings for the rational design of potent Mur ligase inhibitors. PMID:23285193

  18. High-nuclearity homoleptic and heteroleptic coordination cages based on tetra-capped truncated tetrahedral and cuboctahedral metal frameworks.

    PubMed

    Argent, Stephen P; Adams, Harry; Riis-Johannessen, Thomas; Jeffery, John C; Harding, Lindsay P; Ward, Michael D

    2006-01-11

    Two new types of coordination cage have been prepared and structurally characterized: [M16(mu-L1)24]X32 are based on a tetra-capped truncated tetrahedral core and have a bridging ligand L1 along each of the 24 edges; [M12(mu-L1)12(mu3-L2)4]X24 are based on a cuboctahedral core which is supported by a combination of face-capping ligands L2 and edge-bridging ligands L1. The difference between the two illustrates how combinations of ligands with different coordination modes can generate coordination cages which are not available using one ligand type on its own.

  19. GENSURF: A mesh generator for 3D finite element analysis of surface and corner cracks in finite thickness plates subjected to mode-1 loadings

    NASA Technical Reports Server (NTRS)

    Raju, I. S.

    1992-01-01

    A computer program that generates three-dimensional (3D) finite element models for cracked 3D solids was written. This computer program, gensurf, uses minimal input data to generate 3D finite element models for isotropic solids with elliptic or part-elliptic cracks. These models can be used with a 3D finite element program called surf3d. This report documents this mesh generator. In this manual the capabilities, limitations, and organization of gensurf are described. The procedures used to develop 3D finite element models and the input for and the output of gensurf are explained. Several examples are included to illustrate the use of this program. Several input data files are included with this manual so that the users can edit these files to conform to their crack configuration and use them with gensurf.

  20. Coordinate Structures in English.

    ERIC Educational Resources Information Center

    Meyer, Charles F.

    1996-01-01

    Examines comparable speech and writing samples in the British and American components of the International Corpus of English (ICE) to study properties of coordinate structures in English. Findings indicate that "and" is a primary coordinator, that "but" and "or" are more peripheral, and that the concept of…